ScalingIntelligence/swe-bench-verified-codebase-content

hash stringlengths 64 64	content stringlengths 0 1.51M
09179d43ff9d1b2d7b5a0ff238746170ca0cf3a754f864f1c7e2a60e058ff4d9	from sympy import Abs, Rational, Float, S, Symbol, symbols, cos, pi, sqrt, oo from sympy.functions.elementary.trigonometric import tan from sympy.geometry import (Circle, Ellipse, GeometryError, Point, Point2D, Polygon, Ray, RegularPolygon, Segment, Triangle, are_similar, convex_hull, intersection, Line) from sympy.utilities.pytest import raises, slow, warns from sympy.utilities.randtest import verify_numerically from sympy.geometry.polygon import rad, deg from sympy import integrate def feq(a, b): """Test if two floating point values are 'equal'.""" t_float = Float("1.0E-10") return -t_float < a - b < t_float @slow def test_polygon(): x = Symbol('x', real=True) y = Symbol('y', real=True) q = Symbol('q', real=True) u = Symbol('u', real=True) v = Symbol('v', real=True) w = Symbol('w', real=True) x1 = Symbol('x1', real=True) half = Rational(1, 2) a, b, c = Point(0, 0), Point(2, 0), Point(3, 3) t = Triangle(a, b, c) assert Polygon(a, Point(1, 0), b, c) == t assert Polygon(Point(1, 0), b, c, a) == t assert Polygon(b, c, a, Point(1, 0)) == t # 2 "remove folded" tests assert Polygon(a, Point(3, 0), b, c) == t assert Polygon(a, b, Point(3, -1), b, c) == t # remove multiple collinear points assert Polygon(Point(-4, 15), Point(-11, 15), Point(-15, 15), Point(-15, 33/5), Point(-15, -87/10), Point(-15, -15), Point(-42/5, -15), Point(-2, -15), Point(7, -15), Point(15, -15), Point(15, -3), Point(15, 10), Point(15, 15)) == \ Polygon(Point(-15,-15), Point(15,-15), Point(15,15), Point(-15,15)) p1 = Polygon( Point(0, 0), Point(3, -1), Point(6, 0), Point(4, 5), Point(2, 3), Point(0, 3)) p2 = Polygon( Point(6, 0), Point(3, -1), Point(0, 0), Point(0, 3), Point(2, 3), Point(4, 5)) p3 = Polygon( Point(0, 0), Point(3, 0), Point(5, 2), Point(4, 4)) p4 = Polygon( Point(0, 0), Point(4, 4), Point(5, 2), Point(3, 0)) p5 = Polygon( Point(0, 0), Point(4, 4), Point(0, 4)) p6 = Polygon( Point(-11, 1), Point(-9, 6.6), Point(-4, -3), Point(-8.4, -8.7)) p7 = Polygon( Point(x, y), Point(q, u), Point(v, w)) p8 = Polygon( Point(x, y), Point(v, w), Point(q, u)) p9 = Polygon( Point(0, 0), Point(4, 4), Point(3, 0), Point(5, 2)) r = Ray(Point(-9,6.6), Point(-9,5.5)) # # General polygon # assert p1 == p2 assert len(p1.args) == 6 assert len(p1.sides) == 6 assert p1.perimeter == 5 + 2sqrt(10) + sqrt(29) + sqrt(8) assert p1.area == 22 assert not p1.is_convex() assert Polygon((-1, 1), (2, -1), (2, 1), (-1, -1), (3, 0) ).is_convex() is False # ensure convex for both CW and CCW point specification assert p3.is_convex() assert p4.is_convex() dict5 = p5.angles assert dict5[Point(0, 0)] == pi / 4 assert dict5[Point(0, 4)] == pi / 2 assert p5.encloses_point(Point(x, y)) is None assert p5.encloses_point(Point(1, 3)) assert p5.encloses_point(Point(0, 0)) is False assert p5.encloses_point(Point(4, 0)) is False assert p1.encloses(Circle(Point(2.5,2.5),5)) is False assert p1.encloses(Ellipse(Point(2.5,2),5,6)) is False p5.plot_interval('x') == [x, 0, 1] assert p5.distance( Polygon(Point(10, 10), Point(14, 14), Point(10, 14))) == 6 sqrt(2) assert p5.distance( Polygon(Point(1, 8), Point(5, 8), Point(8, 12), Point(1, 12))) == 4 with warns(UserWarning, match="Polygons may intersect producing erroneous output"): Polygon(Point(0, 0), Point(1, 0), Point(1, 1)).distance( Polygon(Point(0, 0), Point(0, 1), Point(1, 1))) assert hash(p5) == hash(Polygon(Point(0, 0), Point(4, 4), Point(0, 4))) assert hash(p1) == hash(p2) assert hash(p7) == hash(p8) assert hash(p3) != hash(p9) assert p5 == Polygon(Point(4, 4), Point(0, 4), Point(0, 0)) assert Polygon(Point(4, 4), Point(0, 4), Point(0, 0)) in p5 assert p5 != Point(0, 4) assert Point(0, 1) in p5 assert p5.arbitrary_point('t').subs(Symbol('t', real=True), 0) == \ Point(0, 0) raises(ValueError, lambda: Polygon( Point(x, 0), Point(0, y), Point(x, y)).arbitrary_point('x')) assert p6.intersection(r) == [Point(-9, -84/13), Point(-9, 33/5)] # # Regular polygon # p1 = RegularPolygon(Point(0, 0), 10, 5) p2 = RegularPolygon(Point(0, 0), 5, 5) raises(GeometryError, lambda: RegularPolygon(Point(0, 0), Point(0, 1), Point(1, 1))) raises(GeometryError, lambda: RegularPolygon(Point(0, 0), 1, 2)) raises(ValueError, lambda: RegularPolygon(Point(0, 0), 1, 2.5)) assert p1 != p2 assert p1.interior_angle == 3pi/5 assert p1.exterior_angle == 2pi/5 assert p2.apothem == 5cos(pi/5) assert p2.circumcenter == p1.circumcenter == Point(0, 0) assert p1.circumradius == p1.radius == 10 assert p2.circumcircle == Circle(Point(0, 0), 5) assert p2.incircle == Circle(Point(0, 0), p2.apothem) assert p2.inradius == p2.apothem == (5 (1 + sqrt(5)) / 4) p2.spin(pi / 10) dict1 = p2.angles assert dict1[Point(0, 5)] == 3 * pi / 5 assert p1.is_convex() assert p1.rotation == 0 assert p1.encloses_point(Point(0, 0)) assert p1.encloses_point(Point(11, 0)) is False assert p2.encloses_point(Point(0, 4.9)) p1.spin(pi/3) assert p1.rotation == pi/3 assert p1.vertices[0] == Point(5, 5sqrt(3)) for var in p1.args: if isinstance(var, Point): assert var == Point(0, 0) else: assert var == 5 or var == 10 or var == pi / 3 assert p1 != Point(0, 0) assert p1 != p5 # while spin works in place (notice that rotation is 2pi/3 below) # rotate returns a new object p1_old = p1 assert p1.rotate(pi/3) == RegularPolygon(Point(0, 0), 10, 5, 2pi/3) assert p1 == p1_old assert p1.area == (-250sqrt(5) + 1250)/(4tan(pi/5)) assert p1.length == 20sqrt(-sqrt(5)/8 + 5/8) assert p1.scale(2, 2) == \ RegularPolygon(p1.center, p1.radius2, p1._n, p1.rotation) assert RegularPolygon((0, 0), 1, 4).scale(2, 3) == \ Polygon(Point(2, 0), Point(0, 3), Point(-2, 0), Point(0, -3)) assert repr(p1) == str(p1) # # Angles # angles = p4.angles assert feq(angles[Point(0, 0)].evalf(), Float("0.7853981633974483")) assert feq(angles[Point(4, 4)].evalf(), Float("1.2490457723982544")) assert feq(angles[Point(5, 2)].evalf(), Float("1.8925468811915388")) assert feq(angles[Point(3, 0)].evalf(), Float("2.3561944901923449")) angles = p3.angles assert feq(angles[Point(0, 0)].evalf(), Float("0.7853981633974483")) assert feq(angles[Point(4, 4)].evalf(), Float("1.2490457723982544")) assert feq(angles[Point(5, 2)].evalf(), Float("1.8925468811915388")) assert feq(angles[Point(3, 0)].evalf(), Float("2.3561944901923449")) # # Triangle # p1 = Point(0, 0) p2 = Point(5, 0) p3 = Point(0, 5) t1 = Triangle(p1, p2, p3) t2 = Triangle(p1, p2, Point(Rational(5, 2), sqrt(Rational(75, 4)))) t3 = Triangle(p1, Point(x1, 0), Point(0, x1)) s1 = t1.sides assert Triangle(p1, p2, p1) == Polygon(p1, p2, p1) == Segment(p1, p2) raises(GeometryError, lambda: Triangle(Point(0, 0))) # Basic stuff assert Triangle(p1, p1, p1) == p1 assert Triangle(p2, p22, p23) == Segment(p2, p23) assert t1.area == Rational(25, 2) assert t1.is_right() assert t2.is_right() is False assert t3.is_right() assert p1 in t1 assert t1.sides[0] in t1 assert Segment((0, 0), (1, 0)) in t1 assert Point(5, 5) not in t2 assert t1.is_convex() assert feq(t1.angles[p1].evalf(), pi.evalf()/2) assert t1.is_equilateral() is False assert t2.is_equilateral() assert t3.is_equilateral() is False assert are_similar(t1, t2) is False assert are_similar(t1, t3) assert are_similar(t2, t3) is False assert t1.is_similar(Point(0, 0)) is False # Bisectors bisectors = t1.bisectors() assert bisectors[p1] == Segment(p1, Point(Rational(5, 2), Rational(5, 2))) ic = (250 - 125sqrt(2)) / 50 assert t1.incenter == Point(ic, ic) # Inradius assert t1.inradius == t1.incircle.radius == 5 - 5sqrt(2)/2 assert t2.inradius == t2.incircle.radius == 5sqrt(3)/6 assert t3.inradius == t3.incircle.radius == x1*2/((2 + sqrt(2))Abs(x1)) # Exradius assert t1.exradii[t1.sides[2]] == 5sqrt(2)/2 # Circumcircle assert t1.circumcircle.center == Point(2.5, 2.5) # Medians + Centroid m = t1.medians assert t1.centroid == Point(Rational(5, 3), Rational(5, 3)) assert m[p1] == Segment(p1, Point(Rational(5, 2), Rational(5, 2))) assert t3.medians[p1] == Segment(p1, Point(x1/2, x1/2)) assert intersection(m[p1], m[p2], m[p3]) == [t1.centroid] assert t1.medial == Triangle(Point(2.5, 0), Point(0, 2.5), Point(2.5, 2.5)) # Nine-point circle assert t1.nine_point_circle == Circle(Point(2.5, 0), Point(0, 2.5), Point(2.5, 2.5)) assert t1.nine_point_circle == Circle(Point(0, 0), Point(0, 2.5), Point(2.5, 2.5)) # Perpendicular altitudes = t1.altitudes assert altitudes[p1] == Segment(p1, Point(Rational(5, 2), Rational(5, 2))) assert altitudes[p2].equals(s1[0]) assert altitudes[p3] == s1[2] assert t1.orthocenter == p1 t = S('''Triangle( Point(100080156402737/5000000000000, 79782624633431/500000000000), Point(39223884078253/2000000000000, 156345163124289/1000000000000), Point(31241359188437/1250000000000, 338338270939941/1000000000000000))''') assert t.orthocenter == S('''Point(-780660869050599840216997''' '''79471538701955848721853/80368430960602242240789074233100000000000000,''' '''20151573611150265741278060334545897615974257/16073686192120448448157''' '''8148466200000000000)''') # Ensure assert len(intersection(bisectors.values())) == 1 assert len(intersection(altitudes.values())) == 1 assert len(intersection(m.values())) == 1 # Distance p1 = Polygon( Point(0, 0), Point(1, 0), Point(1, 1), Point(0, 1)) p2 = Polygon( Point(0, Rational(5)/4), Point(1, Rational(5)/4), Point(1, Rational(9)/4), Point(0, Rational(9)/4)) p3 = Polygon( Point(1, 2), Point(2, 2), Point(2, 1)) p4 = Polygon( Point(1, 1), Point(Rational(6)/5, 1), Point(1, Rational(6)/5)) pt1 = Point(half, half) pt2 = Point(1, 1) '''Polygon to Point''' assert p1.distance(pt1) == half assert p1.distance(pt2) == 0 assert p2.distance(pt1) == Rational(3)/4 assert p3.distance(pt2) == sqrt(2)/2 '''Polygon to Polygon''' # p1.distance(p2) emits a warning with warns(UserWarning, match="Polygons may intersect producing erroneous output"): assert p1.distance(p2) == half/2 assert p1.distance(p3) == sqrt(2)/2 # p3.distance(p4) emits a warning with warns(UserWarning, match="Polygons may intersect producing erroneous output"): assert p3.distance(p4) == (sqrt(2)/2 - sqrt(Rational(2)/25)/2) def test_convex_hull(): p = [Point(-5, -1), Point(-2, 1), Point(-2, -1), Point(-1, -3), Point(0, 0), Point(1, 1), Point(2, 2), Point(2, -1), Point(3, 1), Point(4, -1), Point(6, 2)] ch = Polygon(p[0], p[3], p[9], p[10], p[6], p[1]) #test handling of duplicate points p.append(p[3]) #more than 3 collinear points another_p = [Point(-45, -85), Point(-45, 85), Point(-45, 26), Point(-45, -24)] ch2 = Segment(another_p[0], another_p[1]) assert convex_hull(another_p) == ch2 assert convex_hull(p) == ch assert convex_hull(p[0]) == p[0] assert convex_hull(p[0], p[1]) == Segment(p[0], p[1]) # no unique points assert convex_hull([p[-1]]3) == p[-1] # collection of items assert convex_hull([Point(0, 0), Segment(Point(1, 0), Point(1, 1)), RegularPolygon(Point(2, 0), 2, 4)]) == \ Polygon(Point(0, 0), Point(2, -2), Point(4, 0), Point(2, 2)) def test_encloses(): # square with a dimpled left side s = Polygon(Point(0, 0), Point(1, 0), Point(1, 1), Point(0, 1), Point(S.Half, S.Half)) # the following is True if the polygon isn't treated as closing on itself assert s.encloses(Point(0, S.Half)) is False assert s.encloses(Point(S.Half, S.Half)) is False # it's a vertex assert s.encloses(Point(Rational(3, 4), S.Half)) is True def test_triangle_kwargs(): assert Triangle(sss=(3, 4, 5)) == \ Triangle(Point(0, 0), Point(3, 0), Point(3, 4)) assert Triangle(asa=(30, 2, 30)) == \ Triangle(Point(0, 0), Point(2, 0), Point(1, sqrt(3)/3)) assert Triangle(sas=(1, 45, 2)) == \ Triangle(Point(0, 0), Point(2, 0), Point(sqrt(2)/2, sqrt(2)/2)) assert Triangle(sss=(1, 2, 5)) is None assert deg(rad(180)) == 180 def test_transform(): pts = [Point(0, 0), Point(S(1)/2, S(1)/4), Point(1, 1)] pts_out = [Point(-4, -10), Point(-3, -S(37)/4), Point(-2, -7)] assert Triangle(pts).scale(2, 3, (4, 5)) == Triangle(pts_out) assert RegularPolygon((0, 0), 1, 4).scale(2, 3, (4, 5)) == \ Polygon(Point(-2, -10), Point(-4, -7), Point(-6, -10), Point(-4, -13)) def test_reflect(): x = Symbol('x', real=True) y = Symbol('y', real=True) b = Symbol('b') m = Symbol('m') l = Line((0, b), slope=m) p = Point(x, y) r = p.reflect(l) dp = l.perpendicular_segment(p).length dr = l.perpendicular_segment(r).length assert verify_numerically(dp, dr) t = Triangle((0, 0), (1, 0), (2, 3)) assert Polygon((1, 0), (2, 0), (2, 2)).reflect(Line((3, 0), slope=oo)) \ == Triangle(Point(5, 0), Point(4, 0), Point(4, 2)) assert Polygon((1, 0), (2, 0), (2, 2)).reflect(Line((0, 3), slope=oo)) \ == Triangle(Point(-1, 0), Point(-2, 0), Point(-2, 2)) assert Polygon((1, 0), (2, 0), (2, 2)).reflect(Line((0, 3), slope=0)) \ == Triangle(Point(1, 6), Point(2, 6), Point(2, 4)) assert Polygon((1, 0), (2, 0), (2, 2)).reflect(Line((3, 0), slope=0)) \ == Triangle(Point(1, 0), Point(2, 0), Point(2, -2)) def test_eulerline(): assert Triangle(Point(0, 0), Point(1, 0), Point(0, 1)).eulerline \ == Line(Point2D(0, 0), Point2D(S(1)/2, S(1)/2)) assert Triangle(Point(0, 0), Point(10, 0), Point(5, 5sqrt(3))).eulerline \ == Point2D(5, 5sqrt(3)/3) assert Triangle(Point(4, -6), Point(4, -1), Point(-3, 3)).eulerline \ == Line(Point2D(S(64)/7, 3), Point2D(-S(29)/14, -S(7)/2)) def test_intersection(): poly1 = Triangle(Point(0, 0), Point(1, 0), Point(0, 1)) poly2 = Polygon(Point(0, 1), Point(-5, 0), Point(0, -4), Point(0, S(1)/5), Point(S(1)/2, -0.1), Point(1,0), Point(0, 1)) assert poly1.intersection(poly2) == [Point2D(S(1)/3, 0), Segment(Point(0, S(1)/5), Point(0, 0)), Segment(Point(1, 0), Point(0, 1))] assert poly2.intersection(poly1) == [Point(S(1)/3, 0), Segment(Point(0, 0), Point(0, S(1)/5)), Segment(Point(1, 0), Point(0, 1))] assert poly1.intersection(Point(0, 0)) == [Point(0, 0)] assert poly1.intersection(Point(-12, -43)) == [] assert poly2.intersection(Line((-12, 0), (12, 0))) == [Point(-5, 0), Point(0, 0), Point(S(1)/3, 0), Point(1, 0)] assert poly2.intersection(Line((-12, 12), (12, 12))) == [] assert poly2.intersection(Ray((-3,4), (1,0))) == [Segment(Point(1, 0), Point(0, 1))] assert poly2.intersection(Circle((0, -1), 1)) == [Point(0, -2), Point(0, 0)] assert poly1.intersection(poly1) == [Segment(Point(0, 0), Point(1, 0)), Segment(Point(0, 1), Point(0, 0)), Segment(Point(1, 0), Point(0, 1))] assert poly2.intersection(poly2) == [Segment(Point(-5, 0), Point(0, -4)), Segment(Point(0, -4), Point(0, S(1)/5)), Segment(Point(0, S(1)/5), Point(S(1)/2, -S(1)/10)), Segment(Point(0, 1), Point(-5, 0)), Segment(Point(S(1)/2, -S(1)/10), Point(1, 0)), Segment(Point(1, 0), Point(0, 1))] assert poly2.intersection(Triangle(Point(0, 1), Point(1, 0), Point(-1, 1))) == [Point(-S(5)/7, S(6)/7), Segment(Point2D(0, 1), Point(1, 0))] assert poly1.intersection(RegularPolygon((-12, -15), 3, 3)) == [] def test_parameter_value(): t = Symbol('t') sq = Polygon((0, 0), (0, 1), (1, 1), (1, 0)) assert sq.parameter_value((0.5, 1), t) == {t: S(3)/8} q = Polygon((0, 0), (2, 1), (2, 4), (4, 0)) assert q.parameter_value((4, 0), t) == {t: -6 + 3sqrt(5)} # ~= 0.708 raises(ValueError, lambda: sq.parameter_value((5, 6), t)) def test_issue_12966(): poly = Polygon(Point(0, 0), Point(0, 10), Point(5, 10), Point(5, 5), Point(10, 5), Point(10, 0)) t = Symbol('t') pt = poly.arbitrary_point(t) DELTA = 5/poly.perimeter assert [pt.subs(t, DELTAi) for i in range(int(1/DELTA))] == [ Point(0, 0), Point(0, 5), Point(0, 10), Point(5, 10), Point(5, 5), Point(10, 5), Point(10, 0), Point(5, 0)] def test_second_moment_of_area(): x, y = symbols('x, y') # triangle p1, p2, p3 = [(0, 0), (4, 0), (0, 2)] p = (0, 0) # equation of hypotenuse eq_y = (1-x/4)2 I_yy = integrate((x*2) (integrate(1, (y, 0, eq_y))), (x, 0, 4)) I_xx = integrate(1 * (integrate(y*2, (y, 0, eq_y))), (x, 0, 4)) I_xy = integrate(x (integrate(y, (y, 0, eq_y))), (x, 0, 4)) triangle = Polygon(p1, p2, p3) assert (I_xx - triangle.second_moment_of_area(p)[0]) == 0 assert (I_yy - triangle.second_moment_of_area(p)[1]) == 0 assert (I_xy - triangle.second_moment_of_area(p)[2]) == 0 # rectangle p1, p2, p3, p4=[(0, 0), (4, 0), (4, 2), (0, 2)] I_yy = integrate((x*2) integrate(1, (y, 0, 2)), (x, 0, 4)) I_xx = integrate(1 * integrate(y*2, (y, 0, 2)), (x, 0, 4)) I_xy = integrate(x integrate(y, (y, 0, 2)), (x, 0, 4)) rectangle = Polygon(p1, p2, p3, p4) assert (I_xx - rectangle.second_moment_of_area(p)[0]) == 0 assert (I_yy - rectangle.second_moment_of_area(p)[1]) == 0 assert (I_xy - rectangle.second_moment_of_area(p)[2]) == 0
872bc993f155232066970cdf5a1ef7ec56ec4429061cb9559a8331583a6b2a6f	"""Utilities to deal with sympy.Matrix, numpy and scipy.sparse.""" from __future__ import print_function, division from sympy import MatrixBase, I, Expr, Integer from sympy.core.compatibility import range from sympy.matrices import eye, zeros from sympy.external import import_module __all__ = [ 'numpy_ndarray', 'scipy_sparse_matrix', 'sympy_to_numpy', 'sympy_to_scipy_sparse', 'numpy_to_sympy', 'scipy_sparse_to_sympy', 'flatten_scalar', 'matrix_dagger', 'to_sympy', 'to_numpy', 'to_scipy_sparse', 'matrix_tensor_product', 'matrix_zeros' ] # Conditionally define the base classes for numpy and scipy.sparse arrays # for use in isinstance tests. np = import_module('numpy') if not np: class numpy_ndarray(object): pass else: numpy_ndarray = np.ndarray scipy = import_module('scipy', __import__kwargs={'fromlist': ['sparse']}) if not scipy: class scipy_sparse_matrix(object): pass sparse = None else: sparse = scipy.sparse # Try to find spmatrix. if hasattr(sparse, 'base'): # Newer versions have it under scipy.sparse.base. scipy_sparse_matrix = sparse.base.spmatrix elif hasattr(sparse, 'sparse'): # Older versions have it under scipy.sparse.sparse. scipy_sparse_matrix = sparse.sparse.spmatrix def sympy_to_numpy(m, options): """Convert a sympy Matrix/complex number to a numpy matrix or scalar.""" if not np: raise ImportError dtype = options.get('dtype', 'complex') if isinstance(m, MatrixBase): return np.matrix(m.tolist(), dtype=dtype) elif isinstance(m, Expr): if m.is_Number or m.is_NumberSymbol or m == I: return complex(m) raise TypeError('Expected MatrixBase or complex scalar, got: %r' % m) def sympy_to_scipy_sparse(m, options): """Convert a sympy Matrix/complex number to a numpy matrix or scalar.""" if not np or not sparse: raise ImportError dtype = options.get('dtype', 'complex') if isinstance(m, MatrixBase): return sparse.csr_matrix(np.matrix(m.tolist(), dtype=dtype)) elif isinstance(m, Expr): if m.is_Number or m.is_NumberSymbol or m == I: return complex(m) raise TypeError('Expected MatrixBase or complex scalar, got: %r' % m) def scipy_sparse_to_sympy(m, options): """Convert a scipy.sparse matrix to a sympy matrix.""" return MatrixBase(m.todense()) def numpy_to_sympy(m, options): """Convert a numpy matrix to a sympy matrix.""" return MatrixBase(m) def to_sympy(m, options): """Convert a numpy/scipy.sparse matrix to a sympy matrix.""" if isinstance(m, MatrixBase): return m elif isinstance(m, numpy_ndarray): return numpy_to_sympy(m) elif isinstance(m, scipy_sparse_matrix): return scipy_sparse_to_sympy(m) elif isinstance(m, Expr): return m raise TypeError('Expected sympy/numpy/scipy.sparse matrix, got: %r' % m) def to_numpy(m, options): """Convert a sympy/scipy.sparse matrix to a numpy matrix.""" dtype = options.get('dtype', 'complex') if isinstance(m, (MatrixBase, Expr)): return sympy_to_numpy(m, dtype=dtype) elif isinstance(m, numpy_ndarray): return m elif isinstance(m, scipy_sparse_matrix): return m.todense() raise TypeError('Expected sympy/numpy/scipy.sparse matrix, got: %r' % m) def to_scipy_sparse(m, *options): """Convert a sympy/numpy matrix to a scipy.sparse matrix.""" dtype = options.get('dtype', 'complex') if isinstance(m, (MatrixBase, Expr)): return sympy_to_scipy_sparse(m, dtype=dtype) elif isinstance(m, numpy_ndarray): if not sparse: raise ImportError return sparse.csr_matrix(m) elif isinstance(m, scipy_sparse_matrix): return m raise TypeError('Expected sympy/numpy/scipy.sparse matrix, got: %r' % m) def flatten_scalar(e): """Flatten a 1x1 matrix to a scalar, return larger matrices unchanged.""" if isinstance(e, MatrixBase): if e.shape == (1, 1): e = e[0] if isinstance(e, (numpy_ndarray, scipy_sparse_matrix)): if e.shape == (1, 1): e = complex(e[0, 0]) return e def matrix_dagger(e): """Return the dagger of a sympy/numpy/scipy.sparse matrix.""" if isinstance(e, MatrixBase): return e.H elif isinstance(e, (numpy_ndarray, scipy_sparse_matrix)): return e.conjugate().transpose() raise TypeError('Expected sympy/numpy/scipy.sparse matrix, got: %r' % e) # TODO: Move this into sympy.matricies. def _sympy_tensor_product(matrices): """Compute the kronecker product of a sequence of sympy Matrices. """ from sympy.matrices.expressions.kronecker import matrix_kronecker_product return matrix_kronecker_product(matrices) def _numpy_tensor_product(product): """numpy version of tensor product of multiple arguments.""" if not np: raise ImportError answer = product[0] for item in product[1:]: answer = np.kron(answer, item) return answer def _scipy_sparse_tensor_product(product): """scipy.sparse version of tensor product of multiple arguments.""" if not sparse: raise ImportError answer = product[0] for item in product[1:]: answer = sparse.kron(answer, item) # The final matrices will just be multiplied, so csr is a good final # sparse format. return sparse.csr_matrix(answer) def matrix_tensor_product(product): """Compute the matrix tensor product of sympy/numpy/scipy.sparse matrices.""" if isinstance(product[0], MatrixBase): return _sympy_tensor_product(product) elif isinstance(product[0], numpy_ndarray): return _numpy_tensor_product(product) elif isinstance(product[0], scipy_sparse_matrix): return _scipy_sparse_tensor_product(product) def _numpy_eye(n): """numpy version of complex eye.""" if not np: raise ImportError return np.matrix(np.eye(n, dtype='complex')) def _scipy_sparse_eye(n): """scipy.sparse version of complex eye.""" if not sparse: raise ImportError return sparse.eye(n, n, dtype='complex') def matrix_eye(n, options): """Get the version of eye and tensor_product for a given format.""" format = options.get('format', 'sympy') if format == 'sympy': return eye(n) elif format == 'numpy': return _numpy_eye(n) elif format == 'scipy.sparse': return _scipy_sparse_eye(n) raise NotImplementedError('Invalid format: %r' % format) def _numpy_zeros(m, n, options): """numpy version of zeros.""" dtype = options.get('dtype', 'float64') if not np: raise ImportError return np.zeros((m, n), dtype=dtype) def _scipy_sparse_zeros(m, n, options): """scipy.sparse version of zeros.""" spmatrix = options.get('spmatrix', 'csr') dtype = options.get('dtype', 'float64') if not sparse: raise ImportError if spmatrix == 'lil': return sparse.lil_matrix((m, n), dtype=dtype) elif spmatrix == 'csr': return sparse.csr_matrix((m, n), dtype=dtype) def matrix_zeros(m, n, options): """"Get a zeros matrix for a given format.""" format = options.get('format', 'sympy') dtype = options.get('dtype', 'float64') spmatrix = options.get('spmatrix', 'csr') if format == 'sympy': return zeros(m, n) elif format == 'numpy': return _numpy_zeros(m, n, options) elif format == 'scipy.sparse': return _scipy_sparse_zeros(m, n, options) raise NotImplementedError('Invaild format: %r' % format) def _numpy_matrix_to_zero(e): """Convert a numpy zero matrix to the zero scalar.""" if not np: raise ImportError test = np.zeros_like(e) if np.allclose(e, test): return 0.0 else: return e def _scipy_sparse_matrix_to_zero(e): """Convert a scipy.sparse zero matrix to the zero scalar.""" if not np: raise ImportError edense = e.todense() test = np.zeros_like(edense) if np.allclose(edense, test): return 0.0 else: return e def matrix_to_zero(e): """Convert a zero matrix to the scalar zero.""" if isinstance(e, MatrixBase): if zeros(e.shape) == e: e = Integer(0) elif isinstance(e, numpy_ndarray): e = _numpy_matrix_to_zero(e) elif isinstance(e, scipy_sparse_matrix): e = _scipy_sparse_matrix_to_zero(e) return e
cddd6db8223b4a4bc5f8ae6eea9c5e504197ef96ea0543ddeb719abec9799345	from sympy import Rational, pi, sqrt, sympify, S from sympy.physics.units.quantities import Quantity from sympy.physics.units.dimensions import ( acceleration, action, amount_of_substance, capacitance, charge, conductance, current, energy, force, frequency, information, impedance, inductance, length, luminous_intensity, magnetic_density, magnetic_flux, mass, power, pressure, temperature, time, velocity, voltage) from sympy.physics.units.dimensions import dimsys_default, Dimension from sympy.physics.units.prefixes import ( centi, deci, kilo, micro, milli, nano, pico, kibi, mebi, gibi, tebi, pebi, exbi) One = S.One #### UNITS #### # Dimensionless: percent = percents = Quantity("percent") percent.set_dimension(One) percent.set_scale_factor(Rational(1, 100)) permille = Quantity("permille") permille.set_dimension(One) permille.set_scale_factor(Rational(1, 1000)) # Angular units (dimensionless) rad = radian = radians = Quantity("radian") radian.set_dimension(One) radian.set_scale_factor(One) deg = degree = degrees = Quantity("degree", abbrev="deg") degree.set_dimension(One) degree.set_scale_factor(pi/180) sr = steradian = steradians = Quantity("steradian", abbrev="sr") steradian.set_dimension(One) steradian.set_scale_factor(One) mil = angular_mil = angular_mils = Quantity("angular_mil", abbrev="mil") angular_mil.set_dimension(One) angular_mil.set_scale_factor(2pi/6400) # Base units: m = meter = meters = Quantity("meter", abbrev="m") meter.set_dimension(length) meter.set_scale_factor(One) # NOTE: the `kilogram` has scale factor of 1 in SI. # The current state of the code assumes SI unit dimensions, in # the future this module will be modified in order to be unit system-neutral # (that is, support all kinds of unit systems). kg = kilogram = kilograms = Quantity("kilogram", abbrev="kg") kilogram.set_dimension(mass) kilogram.set_scale_factor(One) s = second = seconds = Quantity("second", abbrev="s") second.set_dimension(time) second.set_scale_factor(One) A = ampere = amperes = Quantity("ampere", abbrev='A') ampere.set_dimension(current) ampere.set_scale_factor(One) K = kelvin = kelvins = Quantity("kelvin", abbrev='K') kelvin.set_dimension(temperature) kelvin.set_scale_factor(One) mol = mole = moles = Quantity("mole", abbrev="mol") mole.set_dimension(amount_of_substance) mole.set_scale_factor(One) cd = candela = candelas = Quantity("candela", abbrev="cd") candela.set_dimension(luminous_intensity) candela.set_scale_factor(One) g = gram = grams = Quantity("gram", abbrev="g") gram.set_dimension(mass) gram.set_scale_factor(kilogram/kilo) mg = milligram = milligrams = Quantity("milligram", abbrev="mg") milligram.set_dimension(mass) milligram.set_scale_factor(milligram) ug = microgram = micrograms = Quantity("microgram", abbrev="ug") microgram.set_dimension(mass) microgram.set_scale_factor(microgram) # derived units newton = newtons = N = Quantity("newton", abbrev="N") newton.set_dimension(force) newton.set_scale_factor(kilogrammeter/second*2) joule = joules = J = Quantity("joule", abbrev="J") joule.set_dimension(energy) joule.set_scale_factor(newtonmeter) watt = watts = W = Quantity("watt", abbrev="W") watt.set_dimension(power) watt.set_scale_factor(joule/second) pascal = pascals = Pa = pa = Quantity("pascal", abbrev="Pa") pascal.set_dimension(pressure) pascal.set_scale_factor(newton/meter*2) hertz = hz = Hz = Quantity("hertz", abbrev="Hz") hertz.set_dimension(frequency) hertz.set_scale_factor(One) # MKSA extension to MKS: derived units coulomb = coulombs = C = Quantity("coulomb", abbrev='C') coulomb.set_dimension(charge) coulomb.set_scale_factor(One) volt = volts = v = V = Quantity("volt", abbrev='V') volt.set_dimension(voltage) volt.set_scale_factor(joule/coulomb) ohm = ohms = Quantity("ohm", abbrev='ohm') ohm.set_dimension(impedance) ohm.set_scale_factor(volt/ampere) siemens = S = mho = mhos = Quantity("siemens", abbrev='S') siemens.set_dimension(conductance) siemens.set_scale_factor(ampere/volt) farad = farads = F = Quantity("farad", abbrev='F') farad.set_dimension(capacitance) farad.set_scale_factor(coulomb/volt) henry = henrys = H = Quantity("henry", abbrev='H') henry.set_dimension(inductance) henry.set_scale_factor(voltsecond/ampere) tesla = teslas = T = Quantity("tesla", abbrev='T') tesla.set_dimension(magnetic_density) tesla.set_scale_factor(voltsecond/meter2) weber = webers = Wb = wb = Quantity("weber", abbrev='Wb') weber.set_dimension(magnetic_flux) weber.set_scale_factor(joule/ampere) # Other derived units: optical_power = dioptre = D = Quantity("dioptre") dioptre.set_dimension(1/length) dioptre.set_scale_factor(1/meter) lux = lx = Quantity("lux") lux.set_dimension(luminous_intensity/length2) lux.set_scale_factor(steradiancandela/meter2) # katal is the SI unit of catalytic activity katal = kat = Quantity("katal") katal.set_dimension(amount_of_substance/time) katal.set_scale_factor(mol/second) # gray is the SI unit of absorbed dose gray = Gy = Quantity("gray") gray.set_dimension(energy/mass) gray.set_scale_factor(meter2/second*2) # becquerel is the SI unit of radioactivity becquerel = Bq = Quantity("becquerel") becquerel.set_dimension(1/time) becquerel.set_scale_factor(1/second) # Common length units km = kilometer = kilometers = Quantity("kilometer", abbrev="km") kilometer.set_dimension(length) kilometer.set_scale_factor(kilometer) dm = decimeter = decimeters = Quantity("decimeter", abbrev="dm") decimeter.set_dimension(length) decimeter.set_scale_factor(decimeter) cm = centimeter = centimeters = Quantity("centimeter", abbrev="cm") centimeter.set_dimension(length) centimeter.set_scale_factor(centimeter) mm = millimeter = millimeters = Quantity("millimeter", abbrev="mm") millimeter.set_dimension(length) millimeter.set_scale_factor(millimeter) um = micrometer = micrometers = micron = microns = Quantity("micrometer", abbrev="um") micrometer.set_dimension(length) micrometer.set_scale_factor(micrometer) nm = nanometer = nanometers = Quantity("nanometer", abbrev="nn") nanometer.set_dimension(length) nanometer.set_scale_factor(nanometer) pm = picometer = picometers = Quantity("picometer", abbrev="pm") picometer.set_dimension(length) picometer.set_scale_factor(picometer) ft = foot = feet = Quantity("foot", abbrev="ft") foot.set_dimension(length) foot.set_scale_factor(Rational(3048, 10000)meter) inch = inches = Quantity("inch") inch.set_dimension(length) inch.set_scale_factor(foot/12) yd = yard = yards = Quantity("yard", abbrev="yd") yard.set_dimension(length) yard.set_scale_factor(3feet) mi = mile = miles = Quantity("mile") mile.set_dimension(length) mile.set_scale_factor(5280feet) nmi = nautical_mile = nautical_miles = Quantity("nautical_mile") nautical_mile.set_dimension(length) nautical_mile.set_scale_factor(6076feet) # Common volume and area units l = liter = liters = Quantity("liter") liter.set_dimension(length3) liter.set_scale_factor(meter3 / 1000) dl = deciliter = deciliters = Quantity("deciliter") deciliter.set_dimension(length3) deciliter.set_scale_factor(liter / 10) cl = centiliter = centiliters = Quantity("centiliter") centiliter.set_dimension(length3) centiliter.set_scale_factor(liter / 100) ml = milliliter = milliliters = Quantity("milliliter") milliliter.set_dimension(length*3) milliliter.set_scale_factor(liter / 1000) # Common time units ms = millisecond = milliseconds = Quantity("millisecond", abbrev="ms") millisecond.set_dimension(time) millisecond.set_scale_factor(millisecond) us = microsecond = microseconds = Quantity("microsecond", abbrev="us") microsecond.set_dimension(time) microsecond.set_scale_factor(microsecond) ns = nanosecond = nanoseconds = Quantity("nanosecond", abbrev="ns") nanosecond.set_dimension(time) nanosecond.set_scale_factor(nanosecond) ps = picosecond = picoseconds = Quantity("picosecond", abbrev="ps") picosecond.set_dimension(time) picosecond.set_scale_factor(picosecond) minute = minutes = Quantity("minute") minute.set_dimension(time) minute.set_scale_factor(60second) h = hour = hours = Quantity("hour") hour.set_dimension(time) hour.set_scale_factor(60minute) day = days = Quantity("day") day.set_dimension(time) day.set_scale_factor(24hour) anomalistic_year = anomalistic_years = Quantity("anomalistic_year") anomalistic_year.set_dimension(time) anomalistic_year.set_scale_factor(365.259636day) sidereal_year = sidereal_years = Quantity("sidereal_year") sidereal_year.set_dimension(time) sidereal_year.set_scale_factor(31558149.540) tropical_year = tropical_years = Quantity("tropical_year") tropical_year.set_dimension(time) tropical_year.set_scale_factor(365.24219day) common_year = common_years = Quantity("common_year") common_year.set_dimension(time) common_year.set_scale_factor(365day) julian_year = julian_years = Quantity("julian_year") julian_year.set_dimension(time) julian_year.set_scale_factor((365 + One/4)day) draconic_year = draconic_years = Quantity("draconic_year") draconic_year.set_dimension(time) draconic_year.set_scale_factor(346.62day) gaussian_year = gaussian_years = Quantity("gaussian_year") gaussian_year.set_dimension(time) gaussian_year.set_scale_factor(365.2568983day) full_moon_cycle = full_moon_cycles = Quantity("full_moon_cycle") full_moon_cycle.set_dimension(time) full_moon_cycle.set_scale_factor(411.78443029day) year = years = tropical_year #### CONSTANTS #### # Newton constant G = gravitational_constant = Quantity("gravitational_constant", abbrev="G") gravitational_constant.set_dimension(length3mass*-1time*-2) gravitational_constant.set_scale_factor(6.67408e-11m*3/(kgs*2)) # speed of light c = speed_of_light = Quantity("speed_of_light", abbrev="c") speed_of_light.set_dimension(velocity) speed_of_light.set_scale_factor(299792458meter/second) # Reduced Planck constant hbar = Quantity("hbar", abbrev="hbar") hbar.set_dimension(action) hbar.set_scale_factor(1.05457266e-34joulesecond) # Planck constant planck = Quantity("planck", abbrev="h") planck.set_dimension(action) planck.set_scale_factor(2pihbar) # Electronvolt eV = electronvolt = electronvolts = Quantity("electronvolt", abbrev="eV") electronvolt.set_dimension(energy) electronvolt.set_scale_factor(1.60219e-19joule) # Avogadro number avogadro_number = Quantity("avogadro_number") avogadro_number.set_dimension(One) avogadro_number.set_scale_factor(6.022140857e23) # Avogadro constant avogadro = avogadro_constant = Quantity("avogadro_constant") avogadro_constant.set_dimension(amount_of_substance-1) avogadro_constant.set_scale_factor(avogadro_number / mol) # Boltzmann constant boltzmann = boltzmann_constant = Quantity("boltzmann_constant") boltzmann_constant.set_dimension(energy/temperature) boltzmann_constant.set_scale_factor(1.38064852e-23joule/kelvin) # Stefan-Boltzmann constant stefan = stefan_boltzmann_constant = Quantity("stefan_boltzmann_constant") stefan_boltzmann_constant.set_dimension(energytime-1length*-2temperature*-4) stefan_boltzmann_constant.set_scale_factor(5.670367e-8joule/(sm2kelvin*4)) # Atomic mass amu = amus = atomic_mass_unit = atomic_mass_constant = Quantity("atomic_mass_constant") atomic_mass_constant.set_dimension(mass) atomic_mass_constant.set_scale_factor(1.660539040e-24gram) # Molar gas constant R = molar_gas_constant = Quantity("molar_gas_constant", abbrev="R") molar_gas_constant.set_dimension(energy/(temperature * amount_of_substance)) molar_gas_constant.set_scale_factor(8.3144598joule/kelvin/mol) # Faraday constant faraday_constant = Quantity("faraday_constant") faraday_constant.set_dimension(charge/amount_of_substance) faraday_constant.set_scale_factor(96485.33289C/mol) # Josephson constant josephson_constant = Quantity("josephson_constant", abbrev="K_j") josephson_constant.set_dimension(frequency/voltage) josephson_constant.set_scale_factor(483597.8525e9hertz/V) # Von Klitzing constant von_klitzing_constant = Quantity("von_klitzing_constant", abbrev="R_k") von_klitzing_constant.set_dimension(voltage/current) von_klitzing_constant.set_scale_factor(25812.8074555ohm) # Acceleration due to gravity (on the Earth surface) gee = gees = acceleration_due_to_gravity = Quantity("acceleration_due_to_gravity", abbrev="g") acceleration_due_to_gravity.set_dimension(acceleration) acceleration_due_to_gravity.set_scale_factor(9.80665meter/second2) # magnetic constant: u0 = magnetic_constant = vacuum_permeability = Quantity("magnetic_constant") magnetic_constant.set_dimension(force/current2) magnetic_constant.set_scale_factor(4pi/10*7 newton/ampere*2) # electric constat: e0 = electric_constant = vacuum_permittivity = Quantity("vacuum_permittivity") vacuum_permittivity.set_dimension(capacitance/length) vacuum_permittivity.set_scale_factor(1/(u0 c*2)) # vacuum impedance: Z0 = vacuum_impedance = Quantity("vacuum_impedance", abbrev='Z_0') vacuum_impedance.set_dimension(impedance) vacuum_impedance.set_scale_factor(u0 c) # Coulomb's constant: coulomb_constant = coulombs_constant = electric_force_constant = Quantity("coulomb_constant", abbrev="k_e") coulomb_constant.set_dimension(forcelength2/charge2) coulomb_constant.set_scale_factor(1/(4pivacuum_permittivity)) atmosphere = atmospheres = atm = Quantity("atmosphere", abbrev="atm") atmosphere.set_dimension(pressure) atmosphere.set_scale_factor(101325 pascal) kPa = kilopascal = Quantity("kilopascal", abbrev="kPa") kilopascal.set_dimension(pressure) kilopascal.set_scale_factor(kiloPa) bar = bars = Quantity("bar", abbrev="bar") bar.set_dimension(pressure) bar.set_scale_factor(100kPa) pound = pounds = Quantity("pound") # exact pound.set_dimension(mass) pound.set_scale_factor(Rational(45359237, 100000000) * kg) psi = Quantity("psi") psi.set_dimension(pressure) psi.set_scale_factor(pound * gee / inch ** 2) dHg0 = 13.5951 # approx value at 0 C mmHg = torr = Quantity("mmHg") mmHg.set_dimension(pressure) mmHg.set_scale_factor(dHg0 * acceleration_due_to_gravity * kilogram / meter2) mmu = mmus = milli_mass_unit = Quantity("milli_mass_unit") milli_mass_unit.set_dimension(mass) milli_mass_unit.set_scale_factor(atomic_mass_unit/1000) quart = quarts = Quantity("quart") quart.set_dimension(length3) quart.set_scale_factor(Rational(231, 4) * inch*3) # Other convenient units and magnitudes ly = lightyear = lightyears = Quantity("lightyear", abbrev="ly") lightyear.set_dimension(length) lightyear.set_scale_factor(speed_of_lightjulian_year) au = astronomical_unit = astronomical_units = Quantity("astronomical_unit", abbrev="AU") astronomical_unit.set_dimension(length) astronomical_unit.set_scale_factor(149597870691meter) # Fundamental Planck units: planck_mass = Quantity("planck_mass", abbrev="m_P") planck_mass.set_dimension(mass) planck_mass.set_scale_factor(sqrt(hbarspeed_of_light/G)) planck_time = Quantity("planck_time", abbrev="t_P") planck_time.set_dimension(time) planck_time.set_scale_factor(sqrt(hbarG/speed_of_light5)) planck_temperature = Quantity("planck_temperature", abbrev="T_P") planck_temperature.set_dimension(temperature) planck_temperature.set_scale_factor(sqrt(hbarspeed_of_light5/G/boltzmann2)) planck_length = Quantity("planck_length", abbrev="l_P") planck_length.set_dimension(length) planck_length.set_scale_factor(sqrt(hbarG/speed_of_light3)) planck_charge = Quantity("planck_charge", abbrev="q_P") planck_charge.set_dimension(charge) planck_charge.set_scale_factor(sqrt(4pielectric_constanthbarspeed_of_light)) # Derived Planck units: planck_area = Quantity("planck_area") planck_area.set_dimension(length2) planck_area.set_scale_factor(planck_length2) planck_volume = Quantity("planck_volume") planck_volume.set_dimension(length3) planck_volume.set_scale_factor(planck_length3) planck_momentum = Quantity("planck_momentum") planck_momentum.set_dimension(massvelocity) planck_momentum.set_scale_factor(planck_mass * speed_of_light) planck_energy = Quantity("planck_energy", abbrev="E_P") planck_energy.set_dimension(energy) planck_energy.set_scale_factor(planck_mass * speed_of_light2) planck_force = Quantity("planck_force", abbrev="F_P") planck_force.set_dimension(force) planck_force.set_scale_factor(planck_energy / planck_length) planck_power = Quantity("planck_power", abbrev="P_P") planck_power.set_dimension(power) planck_power.set_scale_factor(planck_energy / planck_time) planck_density = Quantity("planck_density", abbrev="rho_P") planck_density.set_dimension(mass/length3) planck_density.set_scale_factor(planck_mass / planck_length3) planck_energy_density = Quantity("planck_energy_density", abbrev="rho^E_P") planck_energy_density.set_dimension(energy / length3) planck_energy_density.set_scale_factor(planck_energy / planck_length*3) planck_intensity = Quantity("planck_intensity", abbrev="I_P") planck_intensity.set_dimension(mass time*(-3)) planck_intensity.set_scale_factor(planck_energy_density speed_of_light) planck_angular_frequency = Quantity("planck_angular_frequency", abbrev="omega_P") planck_angular_frequency.set_dimension(1 / time) planck_angular_frequency.set_scale_factor(1 / planck_time) planck_pressure = Quantity("planck_pressure", abbrev="p_P") planck_pressure.set_dimension(pressure) planck_pressure.set_scale_factor(planck_force / planck_length*2) planck_current = Quantity("planck_current", abbrev="I_P") planck_current.set_dimension(current) planck_current.set_scale_factor(planck_charge / planck_time) planck_voltage = Quantity("planck_voltage", abbrev="V_P") planck_voltage.set_dimension(voltage) planck_voltage.set_scale_factor(planck_energy / planck_charge) planck_impedance = Quantity("planck_impedance", abbrev="Z_P") planck_impedance.set_dimension(impedance) planck_impedance.set_scale_factor(planck_voltage / planck_current) planck_acceleration = Quantity("planck_acceleration", abbrev="a_P") planck_acceleration.set_dimension(acceleration) planck_acceleration.set_scale_factor(speed_of_light / planck_time) # Information theory units: bit = bits = Quantity("bit") bit.set_dimension(information) bit.set_scale_factor(One) byte = bytes = Quantity("byte") byte.set_dimension(information) byte.set_scale_factor(8bit) kibibyte = kibibytes = Quantity("kibibyte") kibibyte.set_dimension(information) kibibyte.set_scale_factor(kibibyte) mebibyte = mebibytes = Quantity("mebibyte") mebibyte.set_dimension(information) mebibyte.set_scale_factor(mebibyte) gibibyte = gibibytes = Quantity("gibibyte") gibibyte.set_dimension(information) gibibyte.set_scale_factor(gibibyte) tebibyte = tebibytes = Quantity("tebibyte") tebibyte.set_dimension(information) tebibyte.set_scale_factor(tebibyte) pebibyte = pebibytes = Quantity("pebibyte") pebibyte.set_dimension(information) pebibyte.set_scale_factor(pebibyte) exbibyte = exbibytes = Quantity("exbibyte") exbibyte.set_dimension(information) exbibyte.set_scale_factor(exbibyte) # check that scale factors are the right SI dimensions: for _scale_factor, _dimension in zip( Quantity.SI_quantity_scale_factors.values(), Quantity.SI_quantity_dimension_map.values()): dimex = Quantity.get_dimensional_expr(_scale_factor) if dimex != 1: if not dimsys_default.equivalent_dims(_dimension, Dimension(dimex)): raise ValueError("quantity value and dimension mismatch") del _scale_factor, _dimension
3e6d870448209e3bda0b6f7b1c90ad791615f5ccf76a32c966123fd18c3367d2	from sympy.core.backend import (S, sympify, expand, sqrt, Add, zeros, ImmutableMatrix as Matrix) from sympy import trigsimp from sympy.core.compatibility import unicode from sympy.utilities.misc import filldedent __all__ = ['Vector'] class Vector(object): """The class used to define vectors. It along with ReferenceFrame are the building blocks of describing a classical mechanics system in PyDy and sympy.physics.vector. Attributes ========== simp : Boolean Let certain methods use trigsimp on their outputs """ simp = False def __init__(self, inlist): """This is the constructor for the Vector class. You shouldn't be calling this, it should only be used by other functions. You should be treating Vectors like you would with if you were doing the math by hand, and getting the first 3 from the standard basis vectors from a ReferenceFrame. The only exception is to create a zero vector: zv = Vector(0) """ self.args = [] if inlist == 0: inlist = [] if isinstance(inlist, dict): d = inlist else: d = {} for inp in inlist: if inp[1] in d: d[inp[1]] += inp[0] else: d[inp[1]] = inp[0] for k, v in d.items(): if v != Matrix([0, 0, 0]): self.args.append((v, k)) def __hash__(self): return hash(tuple(self.args)) def __add__(self, other): """The add operator for Vector. """ if other == 0: return self other = _check_vector(other) return Vector(self.args + other.args) def __and__(self, other): """Dot product of two vectors. Returns a scalar, the dot product of the two Vectors Parameters ========== other : Vector The Vector which we are dotting with Examples ======== >>> from sympy.physics.vector import ReferenceFrame, dot >>> from sympy import symbols >>> q1 = symbols('q1') >>> N = ReferenceFrame('N') >>> dot(N.x, N.x) 1 >>> dot(N.x, N.y) 0 >>> A = N.orientnew('A', 'Axis', [q1, N.x]) >>> dot(N.y, A.y) cos(q1) """ from sympy.physics.vector.dyadic import Dyadic if isinstance(other, Dyadic): return NotImplemented other = _check_vector(other) out = S(0) for i, v1 in enumerate(self.args): for j, v2 in enumerate(other.args): out += ((v2[0].T) * (v2[1].dcm(v1[1])) * (v1[0]))[0] if Vector.simp: return trigsimp(sympify(out), recursive=True) else: return sympify(out) def __div__(self, other): """This uses mul and inputs self and 1 divided by other. """ return self.__mul__(sympify(1) / other) __truediv__ = __div__ def __eq__(self, other): """Tests for equality. It is very import to note that this is only as good as the SymPy equality test; False does not always mean they are not equivalent Vectors. If other is 0, and self is empty, returns True. If other is 0 and self is not empty, returns False. If none of the above, only accepts other as a Vector. """ if other == 0: other = Vector(0) try: other = _check_vector(other) except TypeError: return False if (self.args == []) and (other.args == []): return True elif (self.args == []) or (other.args == []): return False frame = self.args[0][1] for v in frame: if expand((self - other) & v) != 0: return False return True def __mul__(self, other): """Multiplies the Vector by a sympifyable expression. Parameters ========== other : Sympifyable The scalar to multiply this Vector with Examples ======== >>> from sympy.physics.vector import ReferenceFrame >>> from sympy import Symbol >>> N = ReferenceFrame('N') >>> b = Symbol('b') >>> V = 10 * b * N.x >>> print(V) 10bN.x """ newlist = [v for v in self.args] for i, v in enumerate(newlist): newlist[i] = (sympify(other) * newlist[i][0], newlist[i][1]) return Vector(newlist) def __ne__(self, other): return not self == other def __neg__(self): return self * -1 def __or__(self, other): """Outer product between two Vectors. A rank increasing operation, which returns a Dyadic from two Vectors Parameters ========== other : Vector The Vector to take the outer product with Examples ======== >>> from sympy.physics.vector import ReferenceFrame, outer >>> N = ReferenceFrame('N') >>> outer(N.x, N.x) (N.x\|N.x) """ from sympy.physics.vector.dyadic import Dyadic other = _check_vector(other) ol = Dyadic(0) for i, v in enumerate(self.args): for i2, v2 in enumerate(other.args): # it looks this way because if we are in the same frame and # use the enumerate function on the same frame in a nested # fashion, then bad things happen ol += Dyadic([(v[0][0] * v2[0][0], v[1].x, v2[1].x)]) ol += Dyadic([(v[0][0] * v2[0][1], v[1].x, v2[1].y)]) ol += Dyadic([(v[0][0] * v2[0][2], v[1].x, v2[1].z)]) ol += Dyadic([(v[0][1] * v2[0][0], v[1].y, v2[1].x)]) ol += Dyadic([(v[0][1] * v2[0][1], v[1].y, v2[1].y)]) ol += Dyadic([(v[0][1] * v2[0][2], v[1].y, v2[1].z)]) ol += Dyadic([(v[0][2] * v2[0][0], v[1].z, v2[1].x)]) ol += Dyadic([(v[0][2] * v2[0][1], v[1].z, v2[1].y)]) ol += Dyadic([(v[0][2] * v2[0][2], v[1].z, v2[1].z)]) return ol def _latex(self, printer=None): """Latex Printing method. """ from sympy.physics.vector.printing import VectorLatexPrinter ar = self.args # just to shorten things if len(ar) == 0: return str(0) ol = [] # output list, to be concatenated to a string for i, v in enumerate(ar): for j in 0, 1, 2: # if the coef of the basis vector is 1, we skip the 1 if ar[i][0][j] == 1: ol.append(' + ' + ar[i][1].latex_vecs[j]) # if the coef of the basis vector is -1, we skip the 1 elif ar[i][0][j] == -1: ol.append(' - ' + ar[i][1].latex_vecs[j]) elif ar[i][0][j] != 0: # If the coefficient of the basis vector is not 1 or -1; # also, we might wrap it in parentheses, for readability. arg_str = VectorLatexPrinter().doprint(ar[i][0][j]) if isinstance(ar[i][0][j], Add): arg_str = "(%s)" % arg_str if arg_str[0] == '-': arg_str = arg_str[1:] str_start = ' - ' else: str_start = ' + ' ol.append(str_start + arg_str + ar[i][1].latex_vecs[j]) outstr = ''.join(ol) if outstr.startswith(' + '): outstr = outstr[3:] elif outstr.startswith(' '): outstr = outstr[1:] return outstr def _pretty(self, printer=None): """Pretty Printing method. """ from sympy.physics.vector.printing import VectorPrettyPrinter from sympy.printing.pretty.stringpict import prettyForm e = self class Fake(object): def render(self, args, kwargs): ar = e.args # just to shorten things if len(ar) == 0: return unicode(0) settings = printer._settings if printer else {} vp = printer if printer else VectorPrettyPrinter(settings) pforms = [] # output list, to be concatenated to a string for i, v in enumerate(ar): for j in 0, 1, 2: # if the coef of the basis vector is 1, we skip the 1 if ar[i][0][j] == 1: pform = vp._print(ar[i][1].pretty_vecs[j]) # if the coef of the basis vector is -1, we skip the 1 elif ar[i][0][j] == -1: pform = vp._print(ar[i][1].pretty_vecs[j]) pform = prettyForm(pform.left(" - ")) bin = prettyForm.NEG pform = prettyForm(binding=bin, pform) elif ar[i][0][j] != 0: # If the basis vector coeff is not 1 or -1, # we might wrap it in parentheses, for readability. pform = vp._print(ar[i][0][j]) if isinstance(ar[i][0][j], Add): tmp = pform.parens() pform = prettyForm(tmp[0], tmp[1]) pform = prettyForm(pform.right(" ", ar[i][1].pretty_vecs[j])) else: continue pforms.append(pform) pform = prettyForm.__add__(pforms) kwargs["wrap_line"] = kwargs.get("wrap_line") kwargs["num_columns"] = kwargs.get("num_columns") out_str = pform.render(args, *kwargs) mlines = [line.rstrip() for line in out_str.split("\n")] return "\n".join(mlines) return Fake() def __ror__(self, other): """Outer product between two Vectors. A rank increasing operation, which returns a Dyadic from two Vectors Parameters ========== other : Vector The Vector to take the outer product with Examples ======== >>> from sympy.physics.vector import ReferenceFrame, outer >>> N = ReferenceFrame('N') >>> outer(N.x, N.x) (N.x\|N.x) """ from sympy.physics.vector.dyadic import Dyadic other = _check_vector(other) ol = Dyadic(0) for i, v in enumerate(other.args): for i2, v2 in enumerate(self.args): # it looks this way because if we are in the same frame and # use the enumerate function on the same frame in a nested # fashion, then bad things happen ol += Dyadic([(v[0][0] v2[0][0], v[1].x, v2[1].x)]) ol += Dyadic([(v[0][0] * v2[0][1], v[1].x, v2[1].y)]) ol += Dyadic([(v[0][0] * v2[0][2], v[1].x, v2[1].z)]) ol += Dyadic([(v[0][1] * v2[0][0], v[1].y, v2[1].x)]) ol += Dyadic([(v[0][1] * v2[0][1], v[1].y, v2[1].y)]) ol += Dyadic([(v[0][1] * v2[0][2], v[1].y, v2[1].z)]) ol += Dyadic([(v[0][2] * v2[0][0], v[1].z, v2[1].x)]) ol += Dyadic([(v[0][2] * v2[0][1], v[1].z, v2[1].y)]) ol += Dyadic([(v[0][2] * v2[0][2], v[1].z, v2[1].z)]) return ol def __rsub__(self, other): return (-1 * self) + other def __str__(self, printer=None, order=True): """Printing method. """ from sympy.physics.vector.printing import VectorStrPrinter if not order or len(self.args) == 1: ar = list(self.args) elif len(self.args) == 0: return str(0) else: d = {v[1]: v[0] for v in self.args} keys = sorted(d.keys(), key=lambda x: x.index) ar = [] for key in keys: ar.append((d[key], key)) ol = [] # output list, to be concatenated to a string for i, v in enumerate(ar): for j in 0, 1, 2: # if the coef of the basis vector is 1, we skip the 1 if ar[i][0][j] == 1: ol.append(' + ' + ar[i][1].str_vecs[j]) # if the coef of the basis vector is -1, we skip the 1 elif ar[i][0][j] == -1: ol.append(' - ' + ar[i][1].str_vecs[j]) elif ar[i][0][j] != 0: # If the coefficient of the basis vector is not 1 or -1; # also, we might wrap it in parentheses, for readability. arg_str = VectorStrPrinter().doprint(ar[i][0][j]) if isinstance(ar[i][0][j], Add): arg_str = "(%s)" % arg_str if arg_str[0] == '-': arg_str = arg_str[1:] str_start = ' - ' else: str_start = ' + ' ol.append(str_start + arg_str + '' + ar[i][1].str_vecs[j]) outstr = ''.join(ol) if outstr.startswith(' + '): outstr = outstr[3:] elif outstr.startswith(' '): outstr = outstr[1:] return outstr def __sub__(self, other): """The subraction operator. """ return self.__add__(other -1) def __xor__(self, other): """The cross product operator for two Vectors. Returns a Vector, expressed in the same ReferenceFrames as self. Parameters ========== other : Vector The Vector which we are crossing with Examples ======== >>> from sympy.physics.vector import ReferenceFrame, Vector >>> from sympy import symbols >>> q1 = symbols('q1') >>> N = ReferenceFrame('N') >>> N.x ^ N.y N.z >>> A = N.orientnew('A', 'Axis', [q1, N.x]) >>> A.x ^ N.y N.z >>> N.y ^ A.x - sin(q1)A.y - cos(q1)A.z """ from sympy.physics.vector.dyadic import Dyadic if isinstance(other, Dyadic): return NotImplemented other = _check_vector(other) if other.args == []: return Vector(0) def _det(mat): """This is needed as a little method for to find the determinant of a list in python; needs to work for a 3x3 list. SymPy's Matrix won't take in Vector, so need a custom function. You shouldn't be calling this. """ return (mat[0][0] * (mat[1][1] * mat[2][2] - mat[1][2] * mat[2][1]) + mat[0][1] * (mat[1][2] * mat[2][0] - mat[1][0] * mat[2][2]) + mat[0][2] * (mat[1][0] * mat[2][1] - mat[1][1] * mat[2][0])) outlist = [] ar = other.args # For brevity for i, v in enumerate(ar): tempx = v[1].x tempy = v[1].y tempz = v[1].z tempm = ([[tempx, tempy, tempz], [self & tempx, self & tempy, self & tempz], [Vector([ar[i]]) & tempx, Vector([ar[i]]) & tempy, Vector([ar[i]]) & tempz]]) outlist += _det(tempm).args return Vector(outlist) # We don't define _repr_png_ here because it would add a large amount of # data to any notebook containing SymPy expressions, without adding # anything useful to the notebook. It can still enabled manually, e.g., # for the qtconsole, with init_printing(). def _repr_latex_(self): """ IPython/Jupyter LaTeX printing To change the behavior of this (e.g., pass in some settings to LaTeX), use init_printing(). init_printing() will also enable LaTeX printing for built in numeric types like ints and container types that contain SymPy objects, like lists and dictionaries of expressions. """ from sympy.printing.latex import latex s = latex(self, mode='plain') return "$\\displaystyle %s$" % s _repr_latex_orig = _repr_latex_ _sympystr = __str__ _sympyrepr = _sympystr __repr__ = __str__ __radd__ = __add__ __rand__ = __and__ __rmul__ = __mul__ def separate(self): """ The constituents of this vector in different reference frames, as per its definition. Returns a dict mapping each ReferenceFrame to the corresponding constituent Vector. Examples ======== >>> from sympy.physics.vector import ReferenceFrame >>> R1 = ReferenceFrame('R1') >>> R2 = ReferenceFrame('R2') >>> v = R1.x + R2.x >>> v.separate() == {R1: R1.x, R2: R2.x} True """ components = {} for x in self.args: components[x[1]] = Vector([x]) return components def dot(self, other): return self & other dot.__doc__ = __and__.__doc__ def cross(self, other): return self ^ other cross.__doc__ = __xor__.__doc__ def outer(self, other): return self \| other outer.__doc__ = __or__.__doc__ def diff(self, var, frame, var_in_dcm=True): """Returns the partial derivative of the vector with respect to a variable in the provided reference frame. Parameters ========== var : Symbol What the partial derivative is taken with respect to. frame : ReferenceFrame The reference frame that the partial derivative is taken in. var_in_dcm : boolean If true, the differentiation algorithm assumes that the variable may be present in any of the direction cosine matrices that relate the frame to the frames of any component of the vector. But if it is known that the variable is not present in the direction cosine matrices, false can be set to skip full reexpression in the desired frame. Examples ======== >>> from sympy import Symbol >>> from sympy.physics.vector import dynamicsymbols, ReferenceFrame >>> from sympy.physics.vector import Vector >>> Vector.simp = True >>> t = Symbol('t') >>> q1 = dynamicsymbols('q1') >>> N = ReferenceFrame('N') >>> A = N.orientnew('A', 'Axis', [q1, N.y]) >>> A.x.diff(t, N) - q1'A.z >>> B = ReferenceFrame('B') >>> u1, u2 = dynamicsymbols('u1, u2') >>> v = u1 A.x + u2 * B.y >>> v.diff(u2, N, var_in_dcm=False) B.y """ from sympy.physics.vector.frame import _check_frame var = sympify(var) _check_frame(frame) inlist = [] for vector_component in self.args: measure_number = vector_component[0] component_frame = vector_component[1] if component_frame == frame: inlist += [(measure_number.diff(var), frame)] else: # If the direction cosine matrix relating the component frame # with the derivative frame does not contain the variable. if not var_in_dcm or (frame.dcm(component_frame).diff(var) == zeros(3, 3)): inlist += [(measure_number.diff(var), component_frame)] else: # else express in the frame reexp_vec_comp = Vector([vector_component]).express(frame) deriv = reexp_vec_comp.args[0][0].diff(var) inlist += Vector([(deriv, frame)]).express(component_frame).args return Vector(inlist) def express(self, otherframe, variables=False): """ Returns a Vector equivalent to this one, expressed in otherframe. Uses the global express method. Parameters ========== otherframe : ReferenceFrame The frame for this Vector to be described in variables : boolean If True, the coordinate symbols(if present) in this Vector are re-expressed in terms otherframe Examples ======== >>> from sympy.physics.vector import ReferenceFrame, Vector, dynamicsymbols >>> q1 = dynamicsymbols('q1') >>> N = ReferenceFrame('N') >>> A = N.orientnew('A', 'Axis', [q1, N.y]) >>> A.x.express(N) cos(q1)N.x - sin(q1)N.z """ from sympy.physics.vector import express return express(self, otherframe, variables=variables) def to_matrix(self, reference_frame): """Returns the matrix form of the vector with respect to the given frame. Parameters ---------- reference_frame : ReferenceFrame The reference frame that the rows of the matrix correspond to. Returns ------- matrix : ImmutableMatrix, shape(3,1) The matrix that gives the 1D vector. Examples ======== >>> from sympy import symbols >>> from sympy.physics.vector import ReferenceFrame >>> from sympy.physics.mechanics.functions import inertia >>> a, b, c = symbols('a, b, c') >>> N = ReferenceFrame('N') >>> vector = a * N.x + b * N.y + c * N.z >>> vector.to_matrix(N) Matrix([ [a], [b], [c]]) >>> beta = symbols('beta') >>> A = N.orientnew('A', 'Axis', (beta, N.x)) >>> vector.to_matrix(A) Matrix([ [ a], [ bcos(beta) + csin(beta)], [-bsin(beta) + ccos(beta)]]) """ return Matrix([self.dot(unit_vec) for unit_vec in reference_frame]).reshape(3, 1) def doit(self, hints): """Calls .doit() on each term in the Vector""" d = {} for v in self.args: d[v[1]] = v[0].applyfunc(lambda x: x.doit(hints)) return Vector(d) def dt(self, otherframe): """ Returns a Vector which is the time derivative of the self Vector, taken in frame otherframe. Calls the global time_derivative method Parameters ========== otherframe : ReferenceFrame The frame to calculate the time derivative in """ from sympy.physics.vector import time_derivative return time_derivative(self, otherframe) def simplify(self): """Returns a simplified Vector.""" d = {} for v in self.args: d[v[1]] = v[0].simplify() return Vector(d) def subs(self, args, kwargs): """Substitution on the Vector. Examples ======== >>> from sympy.physics.vector import ReferenceFrame >>> from sympy import Symbol >>> N = ReferenceFrame('N') >>> s = Symbol('s') >>> a = N.x s >>> a.subs({s: 2}) 2N.x """ d = {} for v in self.args: d[v[1]] = v[0].subs(args, **kwargs) return Vector(d) def magnitude(self): """Returns the magnitude (Euclidean norm) of self.""" return sqrt(self & self) def normalize(self): """Returns a Vector of magnitude 1, codirectional with self.""" return Vector(self.args + []) / self.magnitude() def applyfunc(self, f): """Apply a function to each component of a vector.""" if not callable(f): raise TypeError("`f` must be callable.") d = {} for v in self.args: d[v[1]] = v[0].applyfunc(f) return Vector(d) def free_symbols(self, reference_frame): """ Returns the free symbols in the measure numbers of the vector expressed in the given reference frame. Parameter ========= reference_frame : ReferenceFrame The frame with respect to which the free symbols of the given vector is to be determined. """ return self.to_matrix(reference_frame).free_symbols class VectorTypeError(TypeError): def __init__(self, other, want): msg = filldedent("Expected an instance of %s, but received object " "'%s' of %s." % (type(want), other, type(other))) super(VectorTypeError, self).__init__(msg) def _check_vector(other): if not isinstance(other, Vector): raise TypeError('A Vector must be supplied') return other
9e9b9812bfb03209505a678145dfd029b22dbccfe1009f00d685e3c851fc335a	from sympy.core.backend import sympify, Add, ImmutableMatrix as Matrix from sympy.core.compatibility import unicode from .printing import (VectorLatexPrinter, VectorPrettyPrinter, VectorStrPrinter) __all__ = ['Dyadic'] class Dyadic(object): """A Dyadic object. See: https://en.wikipedia.org/wiki/Dyadic_tensor Kane, T., Levinson, D. Dynamics Theory and Applications. 1985 McGraw-Hill A more powerful way to represent a rigid body's inertia. While it is more complex, by choosing Dyadic components to be in body fixed basis vectors, the resulting matrix is equivalent to the inertia tensor. """ def __init__(self, inlist): """ Just like Vector's init, you shouldn't call this unless creating a zero dyadic. zd = Dyadic(0) Stores a Dyadic as a list of lists; the inner list has the measure number and the two unit vectors; the outerlist holds each unique unit vector pair. """ self.args = [] if inlist == 0: inlist = [] while len(inlist) != 0: added = 0 for i, v in enumerate(self.args): if ((str(inlist[0][1]) == str(self.args[i][1])) and (str(inlist[0][2]) == str(self.args[i][2]))): self.args[i] = (self.args[i][0] + inlist[0][0], inlist[0][1], inlist[0][2]) inlist.remove(inlist[0]) added = 1 break if added != 1: self.args.append(inlist[0]) inlist.remove(inlist[0]) i = 0 # This code is to remove empty parts from the list while i < len(self.args): if ((self.args[i][0] == 0) \| (self.args[i][1] == 0) \| (self.args[i][2] == 0)): self.args.remove(self.args[i]) i -= 1 i += 1 def __add__(self, other): """The add operator for Dyadic. """ other = _check_dyadic(other) return Dyadic(self.args + other.args) def __and__(self, other): """The inner product operator for a Dyadic and a Dyadic or Vector. Parameters ========== other : Dyadic or Vector The other Dyadic or Vector to take the inner product with Examples ======== >>> from sympy.physics.vector import ReferenceFrame, outer >>> N = ReferenceFrame('N') >>> D1 = outer(N.x, N.y) >>> D2 = outer(N.y, N.y) >>> D1.dot(D2) (N.x\|N.y) >>> D1.dot(N.y) N.x """ from sympy.physics.vector.vector import Vector, _check_vector if isinstance(other, Dyadic): other = _check_dyadic(other) ol = Dyadic(0) for i, v in enumerate(self.args): for i2, v2 in enumerate(other.args): ol += v[0] * v2[0] * (v[2] & v2[1]) * (v[1] \| v2[2]) else: other = _check_vector(other) ol = Vector(0) for i, v in enumerate(self.args): ol += v[0] * v[1] * (v[2] & other) return ol def __div__(self, other): """Divides the Dyadic by a sympifyable expression. """ return self.__mul__(1 / other) __truediv__ = __div__ def __eq__(self, other): """Tests for equality. Is currently weak; needs stronger comparison testing """ if other == 0: other = Dyadic(0) other = _check_dyadic(other) if (self.args == []) and (other.args == []): return True elif (self.args == []) or (other.args == []): return False return set(self.args) == set(other.args) def __mul__(self, other): """Multiplies the Dyadic by a sympifyable expression. Parameters ========== other : Sympafiable The scalar to multiply this Dyadic with Examples ======== >>> from sympy.physics.vector import ReferenceFrame, outer >>> N = ReferenceFrame('N') >>> d = outer(N.x, N.x) >>> 5 * d 5(N.x\|N.x) """ newlist = [v for v in self.args] for i, v in enumerate(newlist): newlist[i] = (sympify(other) newlist[i][0], newlist[i][1], newlist[i][2]) return Dyadic(newlist) def __ne__(self, other): return not self == other def __neg__(self): return self * -1 def _latex(self, printer=None): ar = self.args # just to shorten things if len(ar) == 0: return str(0) ol = [] # output list, to be concatenated to a string mlp = VectorLatexPrinter() for i, v in enumerate(ar): # if the coef of the dyadic is 1, we skip the 1 if ar[i][0] == 1: ol.append(' + ' + mlp.doprint(ar[i][1]) + r"\otimes " + mlp.doprint(ar[i][2])) # if the coef of the dyadic is -1, we skip the 1 elif ar[i][0] == -1: ol.append(' - ' + mlp.doprint(ar[i][1]) + r"\otimes " + mlp.doprint(ar[i][2])) # If the coefficient of the dyadic is not 1 or -1, # we might wrap it in parentheses, for readability. elif ar[i][0] != 0: arg_str = mlp.doprint(ar[i][0]) if isinstance(ar[i][0], Add): arg_str = '(%s)' % arg_str if arg_str.startswith('-'): arg_str = arg_str[1:] str_start = ' - ' else: str_start = ' + ' ol.append(str_start + arg_str + mlp.doprint(ar[i][1]) + r"\otimes " + mlp.doprint(ar[i][2])) outstr = ''.join(ol) if outstr.startswith(' + '): outstr = outstr[3:] elif outstr.startswith(' '): outstr = outstr[1:] return outstr def _pretty(self, printer=None): e = self class Fake(object): baseline = 0 def render(self, args, kwargs): ar = e.args # just to shorten things settings = printer._settings if printer else {} if printer: use_unicode = printer._use_unicode else: from sympy.printing.pretty.pretty_symbology import ( pretty_use_unicode) use_unicode = pretty_use_unicode() mpp = printer if printer else VectorPrettyPrinter(settings) if len(ar) == 0: return unicode(0) bar = u"\N{CIRCLED TIMES}" if use_unicode else "\|" ol = [] # output list, to be concatenated to a string for i, v in enumerate(ar): # if the coef of the dyadic is 1, we skip the 1 if ar[i][0] == 1: ol.extend([u" + ", mpp.doprint(ar[i][1]), bar, mpp.doprint(ar[i][2])]) # if the coef of the dyadic is -1, we skip the 1 elif ar[i][0] == -1: ol.extend([u" - ", mpp.doprint(ar[i][1]), bar, mpp.doprint(ar[i][2])]) # If the coefficient of the dyadic is not 1 or -1, # we might wrap it in parentheses, for readability. elif ar[i][0] != 0: if isinstance(ar[i][0], Add): arg_str = mpp._print( ar[i][0]).parens()[0] else: arg_str = mpp.doprint(ar[i][0]) if arg_str.startswith(u"-"): arg_str = arg_str[1:] str_start = u" - " else: str_start = u" + " ol.extend([str_start, arg_str, u" ", mpp.doprint(ar[i][1]), bar, mpp.doprint(ar[i][2])]) outstr = u"".join(ol) if outstr.startswith(u" + "): outstr = outstr[3:] elif outstr.startswith(" "): outstr = outstr[1:] return outstr return Fake() def __rand__(self, other): """The inner product operator for a Vector or Dyadic, and a Dyadic This is for: Vector dot Dyadic Parameters ========== other : Vector The vector we are dotting with Examples ======== >>> from sympy.physics.vector import ReferenceFrame, dot, outer >>> N = ReferenceFrame('N') >>> d = outer(N.x, N.x) >>> dot(N.x, d) N.x """ from sympy.physics.vector.vector import Vector, _check_vector other = _check_vector(other) ol = Vector(0) for i, v in enumerate(self.args): ol += v[0] v[2] * (v[1] & other) return ol def __rsub__(self, other): return (-1 * self) + other def __rxor__(self, other): """For a cross product in the form: Vector x Dyadic Parameters ========== other : Vector The Vector that we are crossing this Dyadic with Examples ======== >>> from sympy.physics.vector import ReferenceFrame, outer, cross >>> N = ReferenceFrame('N') >>> d = outer(N.x, N.x) >>> cross(N.y, d) - (N.z\|N.x) """ from sympy.physics.vector.vector import _check_vector other = _check_vector(other) ol = Dyadic(0) for i, v in enumerate(self.args): ol += v[0] * ((other ^ v[1]) \| v[2]) return ol def __str__(self, printer=None): """Printing method. """ ar = self.args # just to shorten things if len(ar) == 0: return str(0) ol = [] # output list, to be concatenated to a string for i, v in enumerate(ar): # if the coef of the dyadic is 1, we skip the 1 if ar[i][0] == 1: ol.append(' + (' + str(ar[i][1]) + '\|' + str(ar[i][2]) + ')') # if the coef of the dyadic is -1, we skip the 1 elif ar[i][0] == -1: ol.append(' - (' + str(ar[i][1]) + '\|' + str(ar[i][2]) + ')') # If the coefficient of the dyadic is not 1 or -1, # we might wrap it in parentheses, for readability. elif ar[i][0] != 0: arg_str = VectorStrPrinter().doprint(ar[i][0]) if isinstance(ar[i][0], Add): arg_str = "(%s)" % arg_str if arg_str[0] == '-': arg_str = arg_str[1:] str_start = ' - ' else: str_start = ' + ' ol.append(str_start + arg_str + '(' + str(ar[i][1]) + '\|' + str(ar[i][2]) + ')') outstr = ''.join(ol) if outstr.startswith(' + '): outstr = outstr[3:] elif outstr.startswith(' '): outstr = outstr[1:] return outstr def __sub__(self, other): """The subtraction operator. """ return self.__add__(other -1) def __xor__(self, other): """For a cross product in the form: Dyadic x Vector. Parameters ========== other : Vector The Vector that we are crossing this Dyadic with Examples ======== >>> from sympy.physics.vector import ReferenceFrame, outer, cross >>> N = ReferenceFrame('N') >>> d = outer(N.x, N.x) >>> cross(d, N.y) (N.x\|N.z) """ from sympy.physics.vector.vector import _check_vector other = _check_vector(other) ol = Dyadic(0) for i, v in enumerate(self.args): ol += v[0] * (v[1] \| (v[2] ^ other)) return ol # We don't define _repr_png_ here because it would add a large amount of # data to any notebook containing SymPy expressions, without adding # anything useful to the notebook. It can still enabled manually, e.g., # for the qtconsole, with init_printing(). def _repr_latex_(self): """ IPython/Jupyter LaTeX printing To change the behavior of this (e.g., pass in some settings to LaTeX), use init_printing(). init_printing() will also enable LaTeX printing for built in numeric types like ints and container types that contain SymPy objects, like lists and dictionaries of expressions. """ from sympy.printing.latex import latex s = latex(self, mode='plain') return "$\\displaystyle %s$" % s _repr_latex_orig = _repr_latex_ _sympystr = __str__ _sympyrepr = _sympystr __repr__ = __str__ __radd__ = __add__ __rmul__ = __mul__ def express(self, frame1, frame2=None): """Expresses this Dyadic in alternate frame(s) The first frame is the list side expression, the second frame is the right side; if Dyadic is in form A.x\|B.y, you can express it in two different frames. If no second frame is given, the Dyadic is expressed in only one frame. Calls the global express function Parameters ========== frame1 : ReferenceFrame The frame to express the left side of the Dyadic in frame2 : ReferenceFrame If provided, the frame to express the right side of the Dyadic in Examples ======== >>> from sympy.physics.vector import ReferenceFrame, outer, dynamicsymbols >>> N = ReferenceFrame('N') >>> q = dynamicsymbols('q') >>> B = N.orientnew('B', 'Axis', [q, N.z]) >>> d = outer(N.x, N.x) >>> d.express(B, N) cos(q)(B.x\|N.x) - sin(q)(B.y\|N.x) """ from sympy.physics.vector.functions import express return express(self, frame1, frame2) def to_matrix(self, reference_frame, second_reference_frame=None): """Returns the matrix form of the dyadic with respect to one or two reference frames. Parameters ---------- reference_frame : ReferenceFrame The reference frame that the rows and columns of the matrix correspond to. If a second reference frame is provided, this only corresponds to the rows of the matrix. second_reference_frame : ReferenceFrame, optional, default=None The reference frame that the columns of the matrix correspond to. Returns ------- matrix : ImmutableMatrix, shape(3,3) The matrix that gives the 2D tensor form. Examples ======== >>> from sympy import symbols >>> from sympy.physics.vector import ReferenceFrame, Vector >>> Vector.simp = True >>> from sympy.physics.mechanics import inertia >>> Ixx, Iyy, Izz, Ixy, Iyz, Ixz = symbols('Ixx, Iyy, Izz, Ixy, Iyz, Ixz') >>> N = ReferenceFrame('N') >>> inertia_dyadic = inertia(N, Ixx, Iyy, Izz, Ixy, Iyz, Ixz) >>> inertia_dyadic.to_matrix(N) Matrix([ [Ixx, Ixy, Ixz], [Ixy, Iyy, Iyz], [Ixz, Iyz, Izz]]) >>> beta = symbols('beta') >>> A = N.orientnew('A', 'Axis', (beta, N.x)) >>> inertia_dyadic.to_matrix(A) Matrix([ [ Ixx, Ixycos(beta) + Ixzsin(beta), -Ixysin(beta) + Ixzcos(beta)], [ Ixycos(beta) + Ixzsin(beta), Iyycos(2beta)/2 + Iyy/2 + Iyzsin(2beta) - Izzcos(2beta)/2 + Izz/2, -Iyysin(2beta)/2 + Iyzcos(2beta) + Izzsin(2beta)/2], [-Ixysin(beta) + Ixzcos(beta), -Iyysin(2beta)/2 + Iyzcos(2beta) + Izzsin(2beta)/2, -Iyycos(2beta)/2 + Iyy/2 - Iyzsin(2beta) + Izzcos(2beta)/2 + Izz/2]]) """ if second_reference_frame is None: second_reference_frame = reference_frame return Matrix([i.dot(self).dot(j) for i in reference_frame for j in second_reference_frame]).reshape(3, 3) def doit(self, hints): """Calls .doit() on each term in the Dyadic""" return sum([Dyadic([(v[0].doit(hints), v[1], v[2])]) for v in self.args], Dyadic(0)) def dt(self, frame): """Take the time derivative of this Dyadic in a frame. This function calls the global time_derivative method Parameters ========== frame : ReferenceFrame The frame to take the time derivative in Examples ======== >>> from sympy.physics.vector import ReferenceFrame, outer, dynamicsymbols >>> N = ReferenceFrame('N') >>> q = dynamicsymbols('q') >>> B = N.orientnew('B', 'Axis', [q, N.z]) >>> d = outer(N.x, N.x) >>> d.dt(B) - q'(N.y\|N.x) - q'(N.x\|N.y) """ from sympy.physics.vector.functions import time_derivative return time_derivative(self, frame) def simplify(self): """Returns a simplified Dyadic.""" out = Dyadic(0) for v in self.args: out += Dyadic([(v[0].simplify(), v[1], v[2])]) return out def subs(self, args, kwargs): """Substitution on the Dyadic. Examples ======== >>> from sympy.physics.vector import ReferenceFrame >>> from sympy import Symbol >>> N = ReferenceFrame('N') >>> s = Symbol('s') >>> a = s (N.x\|N.x) >>> a.subs({s: 2}) 2(N.x\|N.x) """ return sum([Dyadic([(v[0].subs(args, *kwargs), v[1], v[2])]) for v in self.args], Dyadic(0)) def applyfunc(self, f): """Apply a function to each component of a Dyadic.""" if not callable(f): raise TypeError("`f` must be callable.") out = Dyadic(0) for a, b, c in self.args: out += f(a) (b\|c) return out dot = __and__ cross = __xor__ def _check_dyadic(other): if not isinstance(other, Dyadic): raise TypeError('A Dyadic must be supplied') return other
95f7547c5cfc034cd0cde374437f5f538c4a6a952928f366c9b36bf59f0500b4	""" This module can be used to solve 2D beam bending problems with singularity functions in mechanics. """ from __future__ import print_function, division from sympy.core import S, Symbol, diff, symbols from sympy.solvers import linsolve from sympy.printing import sstr from sympy.functions import SingularityFunction, Piecewise, factorial from sympy.core import sympify from sympy.integrals import integrate from sympy.series import limit from sympy.plotting import plot from sympy.external import import_module from sympy.utilities.decorator import doctest_depends_on from sympy import lambdify matplotlib = import_module('matplotlib', __import__kwargs={'fromlist':['pyplot']}) numpy = import_module('numpy', __import__kwargs={'fromlist':['linspace']}) __doctest_requires__ = {('Beam.plot_loading_results',): ['matplotlib']} class Beam(object): """ A Beam is a structural element that is capable of withstanding load primarily by resisting against bending. Beams are characterized by their cross sectional profile(Second moment of area), their length and their material. .. note:: While solving a beam bending problem, a user should choose its own sign convention and should stick to it. The results will automatically follow the chosen sign convention. Examples ======== There is a beam of length 4 meters. A constant distributed load of 6 N/m is applied from half of the beam till the end. There are two simple supports below the beam, one at the starting point and another at the ending point of the beam. The deflection of the beam at the end is restricted. Using the sign convention of downwards forces being positive. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols, Piecewise >>> E, I = symbols('E, I') >>> R1, R2 = symbols('R1, R2') >>> b = Beam(4, E, I) >>> b.apply_load(R1, 0, -1) >>> b.apply_load(6, 2, 0) >>> b.apply_load(R2, 4, -1) >>> b.bc_deflection = [(0, 0), (4, 0)] >>> b.boundary_conditions {'deflection': [(0, 0), (4, 0)], 'slope': []} >>> b.load R1SingularityFunction(x, 0, -1) + R2SingularityFunction(x, 4, -1) + 6SingularityFunction(x, 2, 0) >>> b.solve_for_reaction_loads(R1, R2) >>> b.load -3SingularityFunction(x, 0, -1) + 6SingularityFunction(x, 2, 0) - 9SingularityFunction(x, 4, -1) >>> b.shear_force() -3SingularityFunction(x, 0, 0) + 6SingularityFunction(x, 2, 1) - 9SingularityFunction(x, 4, 0) >>> b.bending_moment() -3SingularityFunction(x, 0, 1) + 3SingularityFunction(x, 2, 2) - 9SingularityFunction(x, 4, 1) >>> b.slope() (-3SingularityFunction(x, 0, 2)/2 + SingularityFunction(x, 2, 3) - 9SingularityFunction(x, 4, 2)/2 + 7)/(EI) >>> b.deflection() (7x - SingularityFunction(x, 0, 3)/2 + SingularityFunction(x, 2, 4)/4 - 3SingularityFunction(x, 4, 3)/2)/(EI) >>> b.deflection().rewrite(Piecewise) (7x - Piecewise((x3, x > 0), (0, True))/2 - 3Piecewise(((x - 4)3, x - 4 > 0), (0, True))/2 + Piecewise(((x - 2)4, x - 2 > 0), (0, True))/4)/(EI) """ def __init__(self, length, elastic_modulus, second_moment, variable=Symbol('x'), base_char='C'): """Initializes the class. Parameters ========== length : Sympifyable A Symbol or value representing the Beam's length. elastic_modulus : Sympifyable A SymPy expression representing the Beam's Modulus of Elasticity. It is a measure of the stiffness of the Beam material. It can also be a continuous function of position along the beam. second_moment : Sympifyable A SymPy expression representing the Beam's Second moment of area. It is a geometrical property of an area which reflects how its points are distributed with respect to its neutral axis. It can also be a continuous function of position along the beam. variable : Symbol, optional A Symbol object that will be used as the variable along the beam while representing the load, shear, moment, slope and deflection curve. By default, it is set to ``Symbol('x')``. base_char : String, optional A String that will be used as base character to generate sequential symbols for integration constants in cases where boundary conditions are not sufficient to solve them. """ self.length = length self.elastic_modulus = elastic_modulus self.second_moment = second_moment self.variable = variable self._base_char = base_char self._boundary_conditions = {'deflection': [], 'slope': []} self._load = 0 self._applied_loads = [] self._reaction_loads = {} self._composite_type = None self._hinge_position = None def __str__(self): str_sol = 'Beam({}, {}, {})'.format(sstr(self._length), sstr(self._elastic_modulus), sstr(self._second_moment)) return str_sol @property def reaction_loads(self): """ Returns the reaction forces in a dictionary.""" return self._reaction_loads @property def length(self): """Length of the Beam.""" return self._length @length.setter def length(self, l): self._length = sympify(l) @property def variable(self): """ A symbol that can be used as a variable along the length of the beam while representing load distribution, shear force curve, bending moment, slope curve and the deflection curve. By default, it is set to ``Symbol('x')``, but this property is mutable. Examples ======== >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> E, I = symbols('E, I') >>> x, y, z = symbols('x, y, z') >>> b = Beam(4, E, I) >>> b.variable x >>> b.variable = y >>> b.variable y >>> b = Beam(4, E, I, z) >>> b.variable z """ return self._variable @variable.setter def variable(self, v): if isinstance(v, Symbol): self._variable = v else: raise TypeError("""The variable should be a Symbol object.""") @property def elastic_modulus(self): """Young's Modulus of the Beam. """ return self._elastic_modulus @elastic_modulus.setter def elastic_modulus(self, e): self._elastic_modulus = sympify(e) @property def second_moment(self): """Second moment of area of the Beam. """ return self._second_moment @second_moment.setter def second_moment(self, i): self._second_moment = sympify(i) @property def boundary_conditions(self): """ Returns a dictionary of boundary conditions applied on the beam. The dictionary has three kewwords namely moment, slope and deflection. The value of each keyword is a list of tuple, where each tuple contains loaction and value of a boundary condition in the format (location, value). Examples ======== There is a beam of length 4 meters. The bending moment at 0 should be 4 and at 4 it should be 0. The slope of the beam should be 1 at 0. The deflection should be 2 at 0. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> E, I = symbols('E, I') >>> b = Beam(4, E, I) >>> b.bc_deflection = [(0, 2)] >>> b.bc_slope = [(0, 1)] >>> b.boundary_conditions {'deflection': [(0, 2)], 'slope': [(0, 1)]} Here the deflection of the beam should be ``2`` at ``0``. Similarly, the slope of the beam should be ``1`` at ``0``. """ return self._boundary_conditions @property def bc_slope(self): return self._boundary_conditions['slope'] @bc_slope.setter def bc_slope(self, s_bcs): self._boundary_conditions['slope'] = s_bcs @property def bc_deflection(self): return self._boundary_conditions['deflection'] @bc_deflection.setter def bc_deflection(self, d_bcs): self._boundary_conditions['deflection'] = d_bcs def join(self, beam, via="fixed"): """ This method joins two beams to make a new composite beam system. Passed Beam class instance is attached to the right end of calling object. This method can be used to form beams having Discontinuous values of Elastic modulus or Second moment. Parameters ========== beam : Beam class object The Beam object which would be connected to the right of calling object. via : String States the way two Beam object would get connected - For axially fixed Beams, via="fixed" - For Beams connected via hinge, via="hinge" Examples ======== There is a cantilever beam of length 4 meters. For first 2 meters its moment of inertia is `1.5I` and `I` for the other end. A pointload of magnitude 4 N is applied from the top at its free end. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> E, I = symbols('E, I') >>> R1, R2 = symbols('R1, R2') >>> b1 = Beam(2, E, 1.5I) >>> b2 = Beam(2, E, I) >>> b = b1.join(b2, "fixed") >>> b.apply_load(20, 4, -1) >>> b.apply_load(R1, 0, -1) >>> b.apply_load(R2, 0, -2) >>> b.bc_slope = [(0, 0)] >>> b.bc_deflection = [(0, 0)] >>> b.solve_for_reaction_loads(R1, R2) >>> b.load 80SingularityFunction(x, 0, -2) - 20SingularityFunction(x, 0, -1) + 20SingularityFunction(x, 4, -1) >>> b.slope() (((80SingularityFunction(x, 0, 1) - 10SingularityFunction(x, 0, 2) + 10SingularityFunction(x, 4, 2))/I - 120/I)/E + 80.0/(EI))SingularityFunction(x, 2, 0) + 0.666666666666667(80SingularityFunction(x, 0, 1) - 10SingularityFunction(x, 0, 2) + 10SingularityFunction(x, 4, 2))SingularityFunction(x, 0, 0)/(EI) - 0.666666666666667(80SingularityFunction(x, 0, 1) - 10SingularityFunction(x, 0, 2) + 10SingularityFunction(x, 4, 2))SingularityFunction(x, 2, 0)/(EI) """ x = self.variable E = self.elastic_modulus new_length = self.length + beam.length if self.second_moment != beam.second_moment: new_second_moment = Piecewise((self.second_moment, x<=self.length), (beam.second_moment, x<=new_length)) else: new_second_moment = self.second_moment if via == "fixed": new_beam = Beam(new_length, E, new_second_moment, x) new_beam._composite_type = "fixed" return new_beam if via == "hinge": new_beam = Beam(new_length, E, new_second_moment, x) new_beam._composite_type = "hinge" new_beam._hinge_position = self.length return new_beam def apply_support(self, loc, type="fixed"): """ This method applies support to a particular beam object. Parameters ========== loc : Sympifyable Location of point at which support is applied. type : String Determines type of Beam support applied. To apply support structure with - zero degree of freedom, type = "fixed" - one degree of freedom, type = "pin" - two degrees of freedom, type = "roller" Examples ======== There is a beam of length 30 meters. A moment of magnitude 120 Nm is applied in the clockwise direction at the end of the beam. A pointload of magnitude 8 N is applied from the top of the beam at the starting point. There are two simple supports below the beam. One at the end and another one at a distance of 10 meters from the start. The deflection is restricted at both the supports. Using the sign convention of upward forces and clockwise moment being positive. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> E, I = symbols('E, I') >>> b = Beam(30, E, I) >>> b.apply_support(10, 'roller') >>> b.apply_support(30, 'roller') >>> b.apply_load(-8, 0, -1) >>> b.apply_load(120, 30, -2) >>> R_10, R_30 = symbols('R_10, R_30') >>> b.solve_for_reaction_loads(R_10, R_30) >>> b.load -8SingularityFunction(x, 0, -1) + 6SingularityFunction(x, 10, -1) + 120SingularityFunction(x, 30, -2) + 2SingularityFunction(x, 30, -1) >>> b.slope() (-4SingularityFunction(x, 0, 2) + 3SingularityFunction(x, 10, 2) + 120SingularityFunction(x, 30, 1) + SingularityFunction(x, 30, 2) + 4000/3)/(EI) """ if type == "pin" or type == "roller": reaction_load = Symbol('R_'+str(loc)) self.apply_load(reaction_load, loc, -1) self.bc_deflection.append((loc, 0)) else: reaction_load = Symbol('R_'+str(loc)) reaction_moment = Symbol('M_'+str(loc)) self.apply_load(reaction_load, loc, -1) self.apply_load(reaction_moment, loc, -2) self.bc_deflection.append((loc, 0)) self.bc_slope.append((loc, 0)) def apply_load(self, value, start, order, end=None): """ This method adds up the loads given to a particular beam object. Parameters ========== value : Sympifyable The magnitude of an applied load. start : Sympifyable The starting point of the applied load. For point moments and point forces this is the location of application. order : Integer The order of the applied load. - For moments, order = -2 - For point loads, order =-1 - For constant distributed load, order = 0 - For ramp loads, order = 1 - For parabolic ramp loads, order = 2 - ... so on. end : Sympifyable, optional An optional argument that can be used if the load has an end point within the length of the beam. Examples ======== There is a beam of length 4 meters. A moment of magnitude 3 Nm is applied in the clockwise direction at the starting point of the beam. A point load of magnitude 4 N is applied from the top of the beam at 2 meters from the starting point and a parabolic ramp load of magnitude 2 N/m is applied below the beam starting from 2 meters to 3 meters away from the starting point of the beam. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> E, I = symbols('E, I') >>> b = Beam(4, E, I) >>> b.apply_load(-3, 0, -2) >>> b.apply_load(4, 2, -1) >>> b.apply_load(-2, 2, 2, end=3) >>> b.load -3SingularityFunction(x, 0, -2) + 4SingularityFunction(x, 2, -1) - 2SingularityFunction(x, 2, 2) + 2SingularityFunction(x, 3, 0) + 4SingularityFunction(x, 3, 1) + 2SingularityFunction(x, 3, 2) """ x = self.variable value = sympify(value) start = sympify(start) order = sympify(order) self._applied_loads.append((value, start, order, end)) self._load += valueSingularityFunction(x, start, order) if end: if order.is_negative: msg = ("If 'end' is provided the 'order' of the load cannot " "be negative, i.e. 'end' is only valid for distributed " "loads.") raise ValueError(msg) # NOTE : A Taylor series can be used to define the summation of # singularity functions that subtract from the load past the end # point such that it evaluates to zero past 'end'. f = value * x*order for i in range(0, order + 1): self._load -= (f.diff(x, i).subs(x, end - start) SingularityFunction(x, end, i) / factorial(i)) def remove_load(self, value, start, order, end=None): """ This method removes a particular load present on the beam object. Returns a ValueError if the load passed as an argument is not present on the beam. Parameters ========== value : Sympifyable The magnitude of an applied load. start : Sympifyable The starting point of the applied load. For point moments and point forces this is the location of application. order : Integer The order of the applied load. - For moments, order= -2 - For point loads, order=-1 - For constant distributed load, order=0 - For ramp loads, order=1 - For parabolic ramp loads, order=2 - ... so on. end : Sympifyable, optional An optional argument that can be used if the load has an end point within the length of the beam. Examples ======== There is a beam of length 4 meters. A moment of magnitude 3 Nm is applied in the clockwise direction at the starting point of the beam. A pointload of magnitude 4 N is applied from the top of the beam at 2 meters from the starting point and a parabolic ramp load of magnitude 2 N/m is applied below the beam starting from 2 meters to 3 meters away from the starting point of the beam. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> E, I = symbols('E, I') >>> b = Beam(4, E, I) >>> b.apply_load(-3, 0, -2) >>> b.apply_load(4, 2, -1) >>> b.apply_load(-2, 2, 2, end=3) >>> b.load -3SingularityFunction(x, 0, -2) + 4SingularityFunction(x, 2, -1) - 2SingularityFunction(x, 2, 2) + 2SingularityFunction(x, 3, 0) + 4SingularityFunction(x, 3, 1) + 2SingularityFunction(x, 3, 2) >>> b.remove_load(-2, 2, 2, end = 3) >>> b.load -3SingularityFunction(x, 0, -2) + 4SingularityFunction(x, 2, -1) """ x = self.variable value = sympify(value) start = sympify(start) order = sympify(order) if (value, start, order, end) in self._applied_loads: self._load -= valueSingularityFunction(x, start, order) self._applied_loads.remove((value, start, order, end)) else: msg = "No such load distribution exists on the beam object." raise ValueError(msg) if end: # TODO : This is essentially duplicate code wrt to apply_load, # would be better to move it to one location and both methods use # it. if order.is_negative: msg = ("If 'end' is provided the 'order' of the load cannot " "be negative, i.e. 'end' is only valid for distributed " "loads.") raise ValueError(msg) # NOTE : A Taylor series can be used to define the summation of # singularity functions that subtract from the load past the end # point such that it evaluates to zero past 'end'. f = value x*order for i in range(0, order + 1): self._load += (f.diff(x, i).subs(x, end - start) SingularityFunction(x, end, i) / factorial(i)) @property def load(self): """ Returns a Singularity Function expression which represents the load distribution curve of the Beam object. Examples ======== There is a beam of length 4 meters. A moment of magnitude 3 Nm is applied in the clockwise direction at the starting point of the beam. A point load of magnitude 4 N is applied from the top of the beam at 2 meters from the starting point and a parabolic ramp load of magnitude 2 N/m is applied below the beam starting from 3 meters away from the starting point of the beam. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> E, I = symbols('E, I') >>> b = Beam(4, E, I) >>> b.apply_load(-3, 0, -2) >>> b.apply_load(4, 2, -1) >>> b.apply_load(-2, 3, 2) >>> b.load -3SingularityFunction(x, 0, -2) + 4SingularityFunction(x, 2, -1) - 2SingularityFunction(x, 3, 2) """ return self._load @property def applied_loads(self): """ Returns a list of all loads applied on the beam object. Each load in the list is a tuple of form (value, start, order, end). Examples ======== There is a beam of length 4 meters. A moment of magnitude 3 Nm is applied in the clockwise direction at the starting point of the beam. A pointload of magnitude 4 N is applied from the top of the beam at 2 meters from the starting point. Another pointload of magnitude 5 N is applied at same position. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> E, I = symbols('E, I') >>> b = Beam(4, E, I) >>> b.apply_load(-3, 0, -2) >>> b.apply_load(4, 2, -1) >>> b.apply_load(5, 2, -1) >>> b.load -3SingularityFunction(x, 0, -2) + 9SingularityFunction(x, 2, -1) >>> b.applied_loads [(-3, 0, -2, None), (4, 2, -1, None), (5, 2, -1, None)] """ return self._applied_loads def _solve_hinge_beams(self, reactions): """Method to find integration constants and reactional variables in a composite beam connected via hinge. This method resolves the composite Beam into its sub-beams and then equations of shear force, bending moment, slope and deflection are evaluated for both of them separately. These equations are then solved for unknown reactions and integration constants using the boundary conditions applied on the Beam. Equal deflection of both sub-beams at the hinge joint gives us another equation to solve the system. Examples ======== A combined beam, with constant fkexural rigidity EI, is formed by joining a Beam of length 2l to the right of another Beam of length l. The whole beam is fixed at both of its both end. A point load of magnitude P is also applied from the top at a distance of 2l from starting point. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> E, I = symbols('E, I') >>> l=symbols('l', positive=True) >>> b1=Beam(l ,E,I) >>> b2=Beam(2l ,E,I) >>> b=b1.join(b2,"hinge") >>> M1, A1, M2, A2, P = symbols('M1 A1 M2 A2 P') >>> b.apply_load(A1,0,-1) >>> b.apply_load(M1,0,-2) >>> b.apply_load(P,2l,-1) >>> b.apply_load(A2,3l,-1) >>> b.apply_load(M2,3l,-2) >>> b.bc_slope=[(0,0), (3l, 0)] >>> b.bc_deflection=[(0,0), (3l, 0)] >>> b.solve_for_reaction_loads(M1, A1, M2, A2) >>> b.reaction_loads {A1: -5P/18, A2: -13P/18, M1: 5Pl/18, M2: -4Pl/9} >>> b.slope() (5PlSingularityFunction(x, 0, 1)/18 - 5PSingularityFunction(x, 0, 2)/36 + 5PSingularityFunction(x, l, 2)/36)SingularityFunction(x, 0, 0)/(EI) - (5PlSingularityFunction(x, 0, 1)/18 - 5PSingularityFunction(x, 0, 2)/36 + 5PSingularityFunction(x, l, 2)/36)SingularityFunction(x, l, 0)/(EI) + (Pl*2/18 - 4PlSingularityFunction(-l + x, 2l, 1)/9 - 5PSingularityFunction(-l + x, 0, 2)/36 + PSingularityFunction(-l + x, l, 2)/2 - 13PSingularityFunction(-l + x, 2l, 2)/36)SingularityFunction(x, l, 0)/(EI) >>> b.deflection() (5PlSingularityFunction(x, 0, 2)/36 - 5PSingularityFunction(x, 0, 3)/108 + 5PSingularityFunction(x, l, 3)/108)SingularityFunction(x, 0, 0)/(EI) - (5PlSingularityFunction(x, 0, 2)/36 - 5PSingularityFunction(x, 0, 3)/108 + 5PSingularityFunction(x, l, 3)/108)SingularityFunction(x, l, 0)/(EI) + (5Pl3/54 + Pl*2(-l + x)/18 - 2PlSingularityFunction(-l + x, 2l, 2)/9 - 5PSingularityFunction(-l + x, 0, 3)/108 + PSingularityFunction(-l + x, l, 3)/6 - 13PSingularityFunction(-l + x, 2l, 3)/108)SingularityFunction(x, l, 0)/(EI) """ x = self.variable l = self._hinge_position E = self._elastic_modulus I = self._second_moment if isinstance(I, Piecewise): I1 = I.args[0][0] I2 = I.args[1][0] else: I1 = I2 = I load_1 = 0 # Load equation on first segment of composite beam load_2 = 0 # Load equation on second segment of composite beam # Distributing load on both segments for load in self.applied_loads: if load[1] < l: load_1 += load[0]SingularityFunction(x, load[1], load[2]) if load[2] == 0: load_1 -= load[0]SingularityFunction(x, load[3], load[2]) elif load[2] > 0: load_1 -= load[0]SingularityFunction(x, load[3], load[2]) + load[0]SingularityFunction(x, load[3], 0) elif load[1] == l: load_1 += load[0]SingularityFunction(x, load[1], load[2]) load_2 += load[0]SingularityFunction(x, load[1] - l, load[2]) elif load[1] > l: load_2 += load[0]SingularityFunction(x, load[1] - l, load[2]) if load[2] == 0: load_2 -= load[0]SingularityFunction(x, load[3] - l, load[2]) elif load[2] > 0: load_2 -= load[0]SingularityFunction(x, load[3] - l, load[2]) + load[0]SingularityFunction(x, load[3] - l, 0) h = Symbol('h') # Force due to hinge load_1 += hSingularityFunction(x, l, -1) load_2 -= hSingularityFunction(x, 0, -1) eq = [] shear_1 = integrate(load_1, x) shear_curve_1 = limit(shear_1, x, l) eq.append(shear_curve_1) bending_1 = integrate(shear_1, x) moment_curve_1 = limit(bending_1, x, l) eq.append(moment_curve_1) shear_2 = integrate(load_2, x) shear_curve_2 = limit(shear_2, x, self.length - l) eq.append(shear_curve_2) bending_2 = integrate(shear_2, x) moment_curve_2 = limit(bending_2, x, self.length - l) eq.append(moment_curve_2) C1 = Symbol('C1') C2 = Symbol('C2') C3 = Symbol('C3') C4 = Symbol('C4') slope_1 = S(1)/(EI1)(integrate(bending_1, x) + C1) def_1 = S(1)/(EI1)(integrate((EI)slope_1, x) + C1x + C2) slope_2 = S(1)/(EI2)(integrate(integrate(integrate(load_2, x), x), x) + C3) def_2 = S(1)/(EI2)(integrate((EI)slope_2, x) + C4) for position, value in self.bc_slope: if position<l: eq.append(slope_1.subs(x, position) - value) else: eq.append(slope_2.subs(x, position - l) - value) for position, value in self.bc_deflection: if position<l: eq.append(def_1.subs(x, position) - value) else: eq.append(def_2.subs(x, position - l) - value) eq.append(def_1.subs(x, l) - def_2.subs(x, 0)) # Deflection of both the segments at hinge would be equal constants = list(linsolve(eq, C1, C2, C3, C4, h, reactions)) reaction_values = list(constants[0])[5:] self._reaction_loads = dict(zip(reactions, reaction_values)) self._load = self._load.subs(self._reaction_loads) # Substituting constants and reactional load and moments with their corresponding values slope_1 = slope_1.subs({C1: constants[0][0], h:constants[0][4]}).subs(self._reaction_loads) def_1 = def_1.subs({C1: constants[0][0], C2: constants[0][1], h:constants[0][4]}).subs(self._reaction_loads) slope_2 = slope_2.subs({x: x-l, C3: constants[0][2], h:constants[0][4]}).subs(self._reaction_loads) def_2 = def_2.subs({x: x-l,C3: constants[0][2], C4: constants[0][3], h:constants[0][4]}).subs(self._reaction_loads) self._hinge_beam_slope = slope_1SingularityFunction(x, 0, 0) - slope_1SingularityFunction(x, l, 0) + slope_2SingularityFunction(x, l, 0) self._hinge_beam_deflection = def_1SingularityFunction(x, 0, 0) - def_1SingularityFunction(x, l, 0) + def_2SingularityFunction(x, l, 0) def solve_for_reaction_loads(self, reactions): """ Solves for the reaction forces. Examples ======== There is a beam of length 30 meters. A moment of magnitude 120 Nm is applied in the clockwise direction at the end of the beam. A pointload of magnitude 8 N is applied from the top of the beam at the starting point. There are two simple supports below the beam. One at the end and another one at a distance of 10 meters from the start. The deflection is restricted at both the supports. Using the sign convention of upward forces and clockwise moment being positive. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols, linsolve, limit >>> E, I = symbols('E, I') >>> R1, R2 = symbols('R1, R2') >>> b = Beam(30, E, I) >>> b.apply_load(-8, 0, -1) >>> b.apply_load(R1, 10, -1) # Reaction force at x = 10 >>> b.apply_load(R2, 30, -1) # Reaction force at x = 30 >>> b.apply_load(120, 30, -2) >>> b.bc_deflection = [(10, 0), (30, 0)] >>> b.load R1SingularityFunction(x, 10, -1) + R2SingularityFunction(x, 30, -1) - 8SingularityFunction(x, 0, -1) + 120SingularityFunction(x, 30, -2) >>> b.solve_for_reaction_loads(R1, R2) >>> b.reaction_loads {R1: 6, R2: 2} >>> b.load -8SingularityFunction(x, 0, -1) + 6SingularityFunction(x, 10, -1) + 120SingularityFunction(x, 30, -2) + 2SingularityFunction(x, 30, -1) """ if self._composite_type == "hinge": return self._solve_hinge_beams(reactions) x = self.variable l = self.length C3 = Symbol('C3') C4 = Symbol('C4') shear_curve = limit(self.shear_force(), x, l) moment_curve = limit(self.bending_moment(), x, l) slope_eqs = [] deflection_eqs = [] slope_curve = integrate(self.bending_moment(), x) + C3 for position, value in self._boundary_conditions['slope']: eqs = slope_curve.subs(x, position) - value slope_eqs.append(eqs) deflection_curve = integrate(slope_curve, x) + C4 for position, value in self._boundary_conditions['deflection']: eqs = deflection_curve.subs(x, position) - value deflection_eqs.append(eqs) solution = list((linsolve([shear_curve, moment_curve] + slope_eqs + deflection_eqs, (C3, C4) + reactions).args)[0]) solution = solution[2:] self._reaction_loads = dict(zip(reactions, solution)) self._load = self._load.subs(self._reaction_loads) def shear_force(self): """ Returns a Singularity Function expression which represents the shear force curve of the Beam object. Examples ======== There is a beam of length 30 meters. A moment of magnitude 120 Nm is applied in the clockwise direction at the end of the beam. A pointload of magnitude 8 N is applied from the top of the beam at the starting point. There are two simple supports below the beam. One at the end and another one at a distance of 10 meters from the start. The deflection is restricted at both the supports. Using the sign convention of upward forces and clockwise moment being positive. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> E, I = symbols('E, I') >>> R1, R2 = symbols('R1, R2') >>> b = Beam(30, E, I) >>> b.apply_load(-8, 0, -1) >>> b.apply_load(R1, 10, -1) >>> b.apply_load(R2, 30, -1) >>> b.apply_load(120, 30, -2) >>> b.bc_deflection = [(10, 0), (30, 0)] >>> b.solve_for_reaction_loads(R1, R2) >>> b.shear_force() -8SingularityFunction(x, 0, 0) + 6SingularityFunction(x, 10, 0) + 120SingularityFunction(x, 30, -1) + 2SingularityFunction(x, 30, 0) """ x = self.variable return integrate(self.load, x) def max_shear_force(self): """Returns maximum Shear force and its coordinate in the Beam object.""" from sympy import solve, Mul, Interval shear_curve = self.shear_force() x = self.variable terms = shear_curve.args singularity = [] # Points at which shear function changes for term in terms: if isinstance(term, Mul): term = term.args[-1] # SingularityFunction in the term singularity.append(term.args[1]) singularity.sort() singularity = list(set(singularity)) intervals = [] # List of Intervals with discrete value of shear force shear_values = [] # List of values of shear force in each interval for i, s in enumerate(singularity): if s == 0: continue try: shear_slope = Piecewise((float("nan"), x<=singularity[i-1]),(self._load.rewrite(Piecewise), x<s), (float("nan"), True)) points = solve(shear_slope, x) val = [] for point in points: val.append(shear_curve.subs(x, point)) points.extend([singularity[i-1], s]) val.extend([limit(shear_curve, x, singularity[i-1], '+'), limit(shear_curve, x, s, '-')]) val = list(map(abs, val)) max_shear = max(val) shear_values.append(max_shear) intervals.append(points[val.index(max_shear)]) # If shear force in a particular Interval has zero or constant # slope, then above block gives NotImplementedError as # solve can't represent Interval solutions. except NotImplementedError: initial_shear = limit(shear_curve, x, singularity[i-1], '+') final_shear = limit(shear_curve, x, s, '-') # If shear_curve has a constant slope(it is a line). if shear_curve.subs(x, (singularity[i-1] + s)/2) == (initial_shear + final_shear)/2 and initial_shear != final_shear: shear_values.extend([initial_shear, final_shear]) intervals.extend([singularity[i-1], s]) else: # shear_curve has same value in whole Interval shear_values.append(final_shear) intervals.append(Interval(singularity[i-1], s)) shear_values = list(map(abs, shear_values)) maximum_shear = max(shear_values) point = intervals[shear_values.index(maximum_shear)] return (point, maximum_shear) def bending_moment(self): """ Returns a Singularity Function expression which represents the bending moment curve of the Beam object. Examples ======== There is a beam of length 30 meters. A moment of magnitude 120 Nm is applied in the clockwise direction at the end of the beam. A pointload of magnitude 8 N is applied from the top of the beam at the starting point. There are two simple supports below the beam. One at the end and another one at a distance of 10 meters from the start. The deflection is restricted at both the supports. Using the sign convention of upward forces and clockwise moment being positive. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> E, I = symbols('E, I') >>> R1, R2 = symbols('R1, R2') >>> b = Beam(30, E, I) >>> b.apply_load(-8, 0, -1) >>> b.apply_load(R1, 10, -1) >>> b.apply_load(R2, 30, -1) >>> b.apply_load(120, 30, -2) >>> b.bc_deflection = [(10, 0), (30, 0)] >>> b.solve_for_reaction_loads(R1, R2) >>> b.bending_moment() -8SingularityFunction(x, 0, 1) + 6SingularityFunction(x, 10, 1) + 120SingularityFunction(x, 30, 0) + 2SingularityFunction(x, 30, 1) """ x = self.variable return integrate(self.shear_force(), x) def max_bmoment(self): """Returns maximum Shear force and its coordinate in the Beam object.""" from sympy import solve, Mul, Interval bending_curve = self.bending_moment() x = self.variable terms = bending_curve.args singularity = [] # Points at which bending moment changes for term in terms: if isinstance(term, Mul): term = term.args[-1] # SingularityFunction in the term singularity.append(term.args[1]) singularity.sort() singularity = list(set(singularity)) intervals = [] # List of Intervals with discrete value of bending moment moment_values = [] # List of values of bending moment in each interval for i, s in enumerate(singularity): if s == 0: continue try: moment_slope = Piecewise((float("nan"), x<=singularity[i-1]),(self.shear_force().rewrite(Piecewise), x<s), (float("nan"), True)) points = solve(moment_slope, x) val = [] for point in points: val.append(bending_curve.subs(x, point)) points.extend([singularity[i-1], s]) val.extend([limit(bending_curve, x, singularity[i-1], '+'), limit(bending_curve, x, s, '-')]) val = list(map(abs, val)) max_moment = max(val) moment_values.append(max_moment) intervals.append(points[val.index(max_moment)]) # If bending moment in a particular Interval has zero or constant # slope, then above block gives NotImplementedError as solve # can't represent Interval solutions. except NotImplementedError: initial_moment = limit(bending_curve, x, singularity[i-1], '+') final_moment = limit(bending_curve, x, s, '-') # If bending_curve has a constant slope(it is a line). if bending_curve.subs(x, (singularity[i-1] + s)/2) == (initial_moment + final_moment)/2 and initial_moment != final_moment: moment_values.extend([initial_moment, final_moment]) intervals.extend([singularity[i-1], s]) else: # bending_curve has same value in whole Interval moment_values.append(final_moment) intervals.append(Interval(singularity[i-1], s)) moment_values = list(map(abs, moment_values)) maximum_moment = max(moment_values) point = intervals[moment_values.index(maximum_moment)] return (point, maximum_moment) def point_cflexure(self): """ Returns a Set of point(s) with zero bending moment and where bending moment curve of the beam object changes its sign from negative to positive or vice versa. Examples ======== There is is 10 meter long overhanging beam. There are two simple supports below the beam. One at the start and another one at a distance of 6 meters from the start. Point loads of magnitude 10KN and 20KN are applied at 2 meters and 4 meters from start respectively. A Uniformly distribute load of magnitude of magnitude 3KN/m is also applied on top starting from 6 meters away from starting point till end. Using the sign convention of upward forces and clockwise moment being positive. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> E, I = symbols('E, I') >>> b = Beam(10, E, I) >>> b.apply_load(-4, 0, -1) >>> b.apply_load(-46, 6, -1) >>> b.apply_load(10, 2, -1) >>> b.apply_load(20, 4, -1) >>> b.apply_load(3, 6, 0) >>> b.point_cflexure() [10/3] """ from sympy import solve, Piecewise # To restrict the range within length of the Beam moment_curve = Piecewise((float("nan"), self.variable<=0), (self.bending_moment(), self.variable<self.length), (float("nan"), True)) points = solve(moment_curve.rewrite(Piecewise), self.variable, domain=S.Reals) return points def slope(self): """ Returns a Singularity Function expression which represents the slope the elastic curve of the Beam object. Examples ======== There is a beam of length 30 meters. A moment of magnitude 120 Nm is applied in the clockwise direction at the end of the beam. A pointload of magnitude 8 N is applied from the top of the beam at the starting point. There are two simple supports below the beam. One at the end and another one at a distance of 10 meters from the start. The deflection is restricted at both the supports. Using the sign convention of upward forces and clockwise moment being positive. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> E, I = symbols('E, I') >>> R1, R2 = symbols('R1, R2') >>> b = Beam(30, E, I) >>> b.apply_load(-8, 0, -1) >>> b.apply_load(R1, 10, -1) >>> b.apply_load(R2, 30, -1) >>> b.apply_load(120, 30, -2) >>> b.bc_deflection = [(10, 0), (30, 0)] >>> b.solve_for_reaction_loads(R1, R2) >>> b.slope() (-4SingularityFunction(x, 0, 2) + 3SingularityFunction(x, 10, 2) + 120SingularityFunction(x, 30, 1) + SingularityFunction(x, 30, 2) + 4000/3)/(EI) """ x = self.variable E = self.elastic_modulus I = self.second_moment if self._composite_type == "hinge": return self._hinge_beam_slope if not self._boundary_conditions['slope']: return diff(self.deflection(), x) if isinstance(I, Piecewise) and self._composite_type == "fixed": args = I.args slope = 0 conditions = [] prev_slope = 0 prev_end = 0 for i in range(len(args)): if i != 0: prev_end = args[i-1][1].args[1] slope_value = S(1)/Eintegrate(self.bending_moment()/args[i][0], (x, prev_end, x)) if i != len(args) - 1: slope += (prev_slope + slope_value)SingularityFunction(x, prev_end, 0) - \ (prev_slope + slope_value)SingularityFunction(x, args[i][1].args[1], 0) else: slope += (prev_slope + slope_value)SingularityFunction(x, prev_end, 0) prev_slope = slope_value.subs(x, args[i][1].args[1]) return slope C3 = Symbol('C3') slope_curve = integrate(S(1)/(EI)self.bending_moment(), x) + C3 bc_eqs = [] for position, value in self._boundary_conditions['slope']: eqs = slope_curve.subs(x, position) - value bc_eqs.append(eqs) constants = list(linsolve(bc_eqs, C3)) slope_curve = slope_curve.subs({C3: constants[0][0]}) return slope_curve def deflection(self): """ Returns a Singularity Function expression which represents the elastic curve or deflection of the Beam object. Examples ======== There is a beam of length 30 meters. A moment of magnitude 120 Nm is applied in the clockwise direction at the end of the beam. A pointload of magnitude 8 N is applied from the top of the beam at the starting point. There are two simple supports below the beam. One at the end and another one at a distance of 10 meters from the start. The deflection is restricted at both the supports. Using the sign convention of upward forces and clockwise moment being positive. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> E, I = symbols('E, I') >>> R1, R2 = symbols('R1, R2') >>> b = Beam(30, E, I) >>> b.apply_load(-8, 0, -1) >>> b.apply_load(R1, 10, -1) >>> b.apply_load(R2, 30, -1) >>> b.apply_load(120, 30, -2) >>> b.bc_deflection = [(10, 0), (30, 0)] >>> b.solve_for_reaction_loads(R1, R2) >>> b.deflection() (4000x/3 - 4SingularityFunction(x, 0, 3)/3 + SingularityFunction(x, 10, 3) + 60SingularityFunction(x, 30, 2) + SingularityFunction(x, 30, 3)/3 - 12000)/(EI) """ x = self.variable E = self.elastic_modulus I = self.second_moment if self._composite_type == "hinge": return self._hinge_beam_deflection if not self._boundary_conditions['deflection'] and not self._boundary_conditions['slope']: if isinstance(I, Piecewise) and self._composite_type == "fixed": args = I.args conditions = [] prev_slope = 0 prev_def = 0 prev_end = 0 deflection = 0 for i in range(len(args)): if i != 0: prev_end = args[i-1][1].args[1] slope_value = S(1)/Eintegrate(self.bending_moment()/args[i][0], (x, prev_end, x)) recent_segment_slope = prev_slope + slope_value deflection_value = integrate(recent_segment_slope, (x, prev_end, x)) if i != len(args) - 1: deflection += (prev_def + deflection_value)SingularityFunction(x, prev_end, 0) \ - (prev_def + deflection_value)SingularityFunction(x, args[i][1].args[1], 0) else: deflection += (prev_def + deflection_value)SingularityFunction(x, prev_end, 0) prev_slope = slope_value.subs(x, args[i][1].args[1]) prev_def = deflection_value.subs(x, args[i][1].args[1]) return deflection base_char = self._base_char constants = symbols(base_char + '3:5') return S(1)/(EI)integrate(integrate(self.bending_moment(), x), x) + constants[0]x + constants[1] elif not self._boundary_conditions['deflection']: base_char = self._base_char constant = symbols(base_char + '4') return integrate(self.slope(), x) + constant elif not self._boundary_conditions['slope'] and self._boundary_conditions['deflection']: if isinstance(I, Piecewise) and self._composite_type == "fixed": args = I.args conditions = [] prev_slope = 0 prev_def = 0 prev_end = 0 deflection = 0 for i in range(len(args)): if i != 0: prev_end = args[i-1][1].args[1] slope_value = S(1)/Eintegrate(self.bending_moment()/args[i][0], (x, prev_end, x)) recent_segment_slope = prev_slope + slope_value deflection_value = integrate(recent_segment_slope, (x, prev_end, x)) if i != len(args) - 1: deflection += (prev_def + deflection_value)SingularityFunction(x, prev_end, 0) \ - (prev_def + deflection_value)SingularityFunction(x, args[i][1].args[1], 0) else: deflection += (prev_def + deflection_value)SingularityFunction(x, prev_end, 0) prev_slope = slope_value.subs(x, args[i][1].args[1]) prev_def = deflection_value.subs(x, args[i][1].args[1]) return deflection base_char = self._base_char C3, C4 = symbols(base_char + '3:5') # Integration constants slope_curve = integrate(self.bending_moment(), x) + C3 deflection_curve = integrate(slope_curve, x) + C4 bc_eqs = [] for position, value in self._boundary_conditions['deflection']: eqs = deflection_curve.subs(x, position) - value bc_eqs.append(eqs) constants = list(linsolve(bc_eqs, (C3, C4))) deflection_curve = deflection_curve.subs({C3: constants[0][0], C4: constants[0][1]}) return S(1)/(EI)deflection_curve if isinstance(I, Piecewise) and self._composite_type == "fixed": args = I.args conditions = [] prev_slope = 0 prev_def = 0 prev_end = 0 deflection = 0 for i in range(len(args)): if i != 0: prev_end = args[i-1][1].args[1] slope_value = S(1)/Eintegrate(self.bending_moment()/args[i][0], (x, prev_end, x)) recent_segment_slope = prev_slope + slope_value deflection_value = integrate(recent_segment_slope, (x, prev_end, x)) if i != len(args) - 1: deflection += (prev_def + deflection_value)SingularityFunction(x, prev_end, 0) \ - (prev_def + deflection_value)SingularityFunction(x, args[i][1].args[1], 0) else: deflection += (prev_def + deflection_value)SingularityFunction(x, prev_end, 0) prev_slope = slope_value.subs(x, args[i][1].args[1]) prev_def = deflection_value.subs(x, args[i][1].args[1]) return deflection C4 = Symbol('C4') deflection_curve = integrate(self.slope(), x) + C4 bc_eqs = [] for position, value in self._boundary_conditions['deflection']: eqs = deflection_curve.subs(x, position) - value bc_eqs.append(eqs) constants = list(linsolve(bc_eqs, C4)) deflection_curve = deflection_curve.subs({C4: constants[0][0]}) return deflection_curve def max_deflection(self): """ Returns point of max deflection and its coresponding deflection value in a Beam object. """ from sympy import solve, Piecewise # To restrict the range within length of the Beam slope_curve = Piecewise((float("nan"), self.variable<=0), (self.slope(), self.variable<self.length), (float("nan"), True)) points = solve(slope_curve.rewrite(Piecewise), self.variable, domain=S.Reals) deflection_curve = self.deflection() deflections = [deflection_curve.subs(self.variable, x) for x in points] deflections = list(map(abs, deflections)) if len(deflections) != 0: max_def = max(deflections) return (points[deflections.index(max_def)], max_def) else: return None def plot_shear_force(self, subs=None): """ Returns a plot for Shear force present in the Beam object. Parameters ========== subs : dictionary Python dictionary containing Symbols as key and their corresponding values. Examples ======== There is a beam of length 8 meters. A constant distributed load of 10 KN/m is applied from half of the beam till the end. There are two simple supports below the beam, one at the starting point and another at the ending point of the beam. A pointload of magnitude 5 KN is also applied from top of the beam, at a distance of 4 meters from the starting point. Take E = 200 GPa and I = 400(10-6) meter4. Using the sign convention of downwards forces being positive. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> R1, R2 = symbols('R1, R2') >>> b = Beam(8, 200(109), 400(10*-6)) >>> b.apply_load(5000, 2, -1) >>> b.apply_load(R1, 0, -1) >>> b.apply_load(R2, 8, -1) >>> b.apply_load(10000, 4, 0, end=8) >>> b.bc_deflection = [(0, 0), (8, 0)] >>> b.solve_for_reaction_loads(R1, R2) >>> b.plot_shear_force() Plot object containing: [0]: cartesian line: -13750SingularityFunction(x, 0, 0) + 5000SingularityFunction(x, 2, 0) + 10000SingularityFunction(x, 4, 1) - 31250SingularityFunction(x, 8, 0) - 10000SingularityFunction(x, 8, 1) for x over (0.0, 8.0) """ shear_force = self.shear_force() if subs is None: subs = {} for sym in shear_force.atoms(Symbol): if sym == self.variable: continue if sym not in subs: raise ValueError('Value of %s was not passed.' %sym) if self.length in subs: length = subs[self.length] else: length = self.length return plot(shear_force.subs(subs), (self.variable, 0, length), title='Shear Force', xlabel='position', ylabel='Value', line_color='g') def plot_bending_moment(self, subs=None): """ Returns a plot for Bending moment present in the Beam object. Parameters ========== subs : dictionary Python dictionary containing Symbols as key and their corresponding values. Examples ======== There is a beam of length 8 meters. A constant distributed load of 10 KN/m is applied from half of the beam till the end. There are two simple supports below the beam, one at the starting point and another at the ending point of the beam. A pointload of magnitude 5 KN is also applied from top of the beam, at a distance of 4 meters from the starting point. Take E = 200 GPa and I = 400(10-6) meter4. Using the sign convention of downwards forces being positive. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> R1, R2 = symbols('R1, R2') >>> b = Beam(8, 200(10*9), 400(10*-6)) >>> b.apply_load(5000, 2, -1) >>> b.apply_load(R1, 0, -1) >>> b.apply_load(R2, 8, -1) >>> b.apply_load(10000, 4, 0, end=8) >>> b.bc_deflection = [(0, 0), (8, 0)] >>> b.solve_for_reaction_loads(R1, R2) >>> b.plot_bending_moment() Plot object containing: [0]: cartesian line: -13750SingularityFunction(x, 0, 1) + 5000SingularityFunction(x, 2, 1) + 5000SingularityFunction(x, 4, 2) - 31250SingularityFunction(x, 8, 1) - 5000SingularityFunction(x, 8, 2) for x over (0.0, 8.0) """ bending_moment = self.bending_moment() if subs is None: subs = {} for sym in bending_moment.atoms(Symbol): if sym == self.variable: continue if sym not in subs: raise ValueError('Value of %s was not passed.' %sym) if self.length in subs: length = subs[self.length] else: length = self.length return plot(bending_moment.subs(subs), (self.variable, 0, length), title='Bending Moment', xlabel='position', ylabel='Value', line_color='b') def plot_slope(self, subs=None): """ Returns a plot for slope of deflection curve of the Beam object. Parameters ========== subs : dictionary Python dictionary containing Symbols as key and their corresponding values. Examples ======== There is a beam of length 8 meters. A constant distributed load of 10 KN/m is applied from half of the beam till the end. There are two simple supports below the beam, one at the starting point and another at the ending point of the beam. A pointload of magnitude 5 KN is also applied from top of the beam, at a distance of 4 meters from the starting point. Take E = 200 GPa and I = 400(10-6) meter4. Using the sign convention of downwards forces being positive. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> R1, R2 = symbols('R1, R2') >>> b = Beam(8, 200(10*9), 400(10*-6)) >>> b.apply_load(5000, 2, -1) >>> b.apply_load(R1, 0, -1) >>> b.apply_load(R2, 8, -1) >>> b.apply_load(10000, 4, 0, end=8) >>> b.bc_deflection = [(0, 0), (8, 0)] >>> b.solve_for_reaction_loads(R1, R2) >>> b.plot_slope() Plot object containing: [0]: cartesian line: -8.59375e-5SingularityFunction(x, 0, 2) + 3.125e-5SingularityFunction(x, 2, 2) + 2.08333333333333e-5SingularityFunction(x, 4, 3) - 0.0001953125SingularityFunction(x, 8, 2) - 2.08333333333333e-5SingularityFunction(x, 8, 3) + 0.00138541666666667 for x over (0.0, 8.0) """ slope = self.slope() if subs is None: subs = {} for sym in slope.atoms(Symbol): if sym == self.variable: continue if sym not in subs: raise ValueError('Value of %s was not passed.' %sym) if self.length in subs: length = subs[self.length] else: length = self.length return plot(slope.subs(subs), (self.variable, 0, length), title='Slope', xlabel='position', ylabel='Value', line_color='m') def plot_deflection(self, subs=None): """ Returns a plot for deflection curve of the Beam object. Parameters ========== subs : dictionary Python dictionary containing Symbols as key and their corresponding values. Examples ======== There is a beam of length 8 meters. A constant distributed load of 10 KN/m is applied from half of the beam till the end. There are two simple supports below the beam, one at the starting point and another at the ending point of the beam. A pointload of magnitude 5 KN is also applied from top of the beam, at a distance of 4 meters from the starting point. Take E = 200 GPa and I = 400(10-6) meter4. Using the sign convention of downwards forces being positive. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> R1, R2 = symbols('R1, R2') >>> b = Beam(8, 200(10*9), 400(10*-6)) >>> b.apply_load(5000, 2, -1) >>> b.apply_load(R1, 0, -1) >>> b.apply_load(R2, 8, -1) >>> b.apply_load(10000, 4, 0, end=8) >>> b.bc_deflection = [(0, 0), (8, 0)] >>> b.solve_for_reaction_loads(R1, R2) >>> b.plot_deflection() Plot object containing: [0]: cartesian line: 0.00138541666666667x - 2.86458333333333e-5SingularityFunction(x, 0, 3) + 1.04166666666667e-5SingularityFunction(x, 2, 3) + 5.20833333333333e-6SingularityFunction(x, 4, 4) - 6.51041666666667e-5SingularityFunction(x, 8, 3) - 5.20833333333333e-6SingularityFunction(x, 8, 4) for x over (0.0, 8.0) """ deflection = self.deflection() if subs is None: subs = {} for sym in deflection.atoms(Symbol): if sym == self.variable: continue if sym not in subs: raise ValueError('Value of %s was not passed.' %sym) if self.length in subs: length = subs[self.length] else: length = self.length return plot(deflection.subs(subs), (self.variable, 0, length), title='Deflection', xlabel='position', ylabel='Value', line_color='r') @doctest_depends_on(modules=('numpy', 'matplotlib',)) def plot_loading_results(self, subs=None): """ Returns Axes object containing subplots of Shear Force, Bending Moment, Slope and Deflection of the Beam object. Parameters ========== subs : dictionary Python dictionary containing Symbols as key and their corresponding values. .. note:: This method only works if numpy and matplotlib libraries are installed on the system. Examples ======== There is a beam of length 8 meters. A constant distributed load of 10 KN/m is applied from half of the beam till the end. There are two simple supports below the beam, one at the starting point and another at the ending point of the beam. A pointload of magnitude 5 KN is also applied from top of the beam, at a distance of 4 meters from the starting point. Take E = 200 GPa and I = 400(10-6) meter4. Using the sign convention of downwards forces being positive. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> R1, R2 = symbols('R1, R2') >>> b = Beam(8, 200(109), 400(10*-6)) >>> b.apply_load(5000, 2, -1) >>> b.apply_load(R1, 0, -1) >>> b.apply_load(R2, 8, -1) >>> b.apply_load(10000, 4, 0, end=8) >>> b.bc_deflection = [(0, 0), (8, 0)] >>> b.solve_for_reaction_loads(R1, R2) >>> axes = b.plot_loading_results() """ if matplotlib is None: raise ImportError('Install matplotlib to use this method.') else: plt = matplotlib.pyplot if numpy is None: raise ImportError('Install numpy to use this method.') else: linspace = numpy.linspace length = self.length variable = self.variable if subs is None: subs = {} for sym in self.deflection().atoms(Symbol): if sym == self.variable: continue if sym not in subs: raise ValueError('Value of %s was not passed.' % sym) if self.length in subs: length = subs[self.length] else: length = self.length # As we are using matplotlib directly in this method, we need to change # SymPy methods to numpy functions. shear = lambdify(variable, self.shear_force().subs(subs).rewrite(Piecewise), 'numpy') moment = lambdify(variable, self.bending_moment().subs(subs).rewrite(Piecewise), 'numpy') slope = lambdify(variable, self.slope().subs(subs).rewrite(Piecewise), 'numpy') deflection = lambdify(variable, self.deflection().subs(subs).rewrite(Piecewise), 'numpy') points = linspace(0, float(length), num=100length) # Creating a grid for subplots with 2 rows and 2 columns fig, axs = plt.subplots(4, 1) # axs is a 2D-numpy array containing axes axs[0].plot(points, shear(points)) axs[0].set_title("Shear Force") axs[1].plot(points, moment(points)) axs[1].set_title("Bending Moment") axs[2].plot(points, slope(points)) axs[2].set_title("Slope") axs[3].plot(points, deflection(points)) axs[3].set_title("Deflection") fig.tight_layout() # For better spacing between subplots return axs class Beam3D(Beam): """ This class handles loads applied in any direction of a 3D space along with unequal values of Second moment along different axes. .. note:: While solving a beam bending problem, a user should choose its own sign convention and should stick to it. The results will automatically follow the chosen sign convention. This class assumes that any kind of distributed load/moment is applied through out the span of a beam. Examples ======== There is a beam of l meters long. A constant distributed load of magnitude q is applied along y-axis from start till the end of beam. A constant distributed moment of magnitude m is also applied along z-axis from start till the end of beam. Beam is fixed at both of its end. So, deflection of the beam at the both ends is restricted. >>> from sympy.physics.continuum_mechanics.beam import Beam3D >>> from sympy import symbols, simplify >>> l, E, G, I, A = symbols('l, E, G, I, A') >>> b = Beam3D(l, E, G, I, A) >>> x, q, m = symbols('x, q, m') >>> b.apply_load(q, 0, 0, dir="y") >>> b.apply_moment_load(m, 0, -1, dir="z") >>> b.shear_force() [0, -qx, 0] >>> b.bending_moment() [0, 0, -mx + qx2/2] >>> b.bc_slope = [(0, [0, 0, 0]), (l, [0, 0, 0])] >>> b.bc_deflection = [(0, [0, 0, 0]), (l, [0, 0, 0])] >>> b.solve_slope_deflection() >>> b.slope() [0, 0, lx(-lq + 3l(AGl(lq - 2m) + 12EIq)/(2(AGl2 + 12EI)) + 3m)/(6EI) + qx3/(6EI) + x2(-l(AGl(lq - 2m) + 12EIq)/(2(AGl*2 + 12EI)) - m)/(2EI)] >>> dx, dy, dz = b.deflection() >>> dx 0 >>> dz 0 >>> expectedy = ( ... -l2qx2/(12EI) + l2x*2(AGl(lq - 2m) + 12EIq)/(8EI(AGl2 + 12EI)) ... + lmx2/(4EI) - lx*3(AGl(lq - 2m) + 12EIq)/(12EI(AGl2 + 12EI)) - mx*3/(6EI) ... + qx*4/(24EI) + lx(AGl(lq - 2m) + 12EIq)/(2AG(AGl*2 + 12EI)) - qx*2/(2AG) ... ) >>> simplify(dy - expectedy) 0 References ========== .. [1] http://homes.civil.aau.dk/jc/FemteSemester/Beams3D.pdf """ def __init__(self, length, elastic_modulus, shear_modulus , second_moment, area, variable=Symbol('x')): """Initializes the class. Parameters ========== length : Sympifyable A Symbol or value representing the Beam's length. elastic_modulus : Sympifyable A SymPy expression representing the Beam's Modulus of Elasticity. It is a measure of the stiffness of the Beam material. shear_modulus : Sympifyable A SymPy expression representing the Beam's Modulus of rigidity. It is a measure of rigidity of the Beam material. second_moment : Sympifyable or list A list of two elements having SymPy expression representing the Beam's Second moment of area. First value represent Second moment across y-axis and second across z-axis. Single SymPy expression can be passed if both values are same area : Sympifyable A SymPy expression representing the Beam's cross-sectional area in a plane prependicular to length of the Beam. variable : Symbol, optional A Symbol object that will be used as the variable along the beam while representing the load, shear, moment, slope and deflection curve. By default, it is set to ``Symbol('x')``. """ self.length = length self.elastic_modulus = elastic_modulus self.shear_modulus = shear_modulus self.second_moment = second_moment self.area = area self.variable = variable self._boundary_conditions = {'deflection': [], 'slope': []} self._load_vector = [0, 0, 0] self._moment_load_vector = [0, 0, 0] self._load_Singularity = [0, 0, 0] self._reaction_loads = {} self._slope = [0, 0, 0] self._deflection = [0, 0, 0] @property def shear_modulus(self): """Young's Modulus of the Beam. """ return self._shear_modulus @shear_modulus.setter def shear_modulus(self, e): self._shear_modulus = sympify(e) @property def second_moment(self): """Second moment of area of the Beam. """ return self._second_moment @second_moment.setter def second_moment(self, i): if isinstance(i, list): i = [sympify(x) for x in i] self._second_moment = i else: self._second_moment = sympify(i) @property def area(self): """Cross-sectional area of the Beam. """ return self._area @area.setter def area(self, a): self._area = sympify(a) @property def load_vector(self): """ Returns a three element list representing the load vector. """ return self._load_vector @property def moment_load_vector(self): """ Returns a three element list representing moment loads on Beam. """ return self._moment_load_vector @property def boundary_conditions(self): """ Returns a dictionary of boundary conditions applied on the beam. The dictionary has two keywords namely slope and deflection. The value of each keyword is a list of tuple, where each tuple contains loaction and value of a boundary condition in the format (location, value). Further each value is a list corresponding to slope or deflection(s) values along three axes at that location. Examples ======== There is a beam of length 4 meters. The slope at 0 should be 4 along the x-axis and 0 along others. At the other end of beam, deflection along all the three axes should be zero. >>> from sympy.physics.continuum_mechanics.beam import Beam3D >>> from sympy import symbols >>> l, E, G, I, A, x = symbols('l, E, G, I, A, x') >>> b = Beam3D(30, E, G, I, A, x) >>> b.bc_slope = [(0, (4, 0, 0))] >>> b.bc_deflection = [(4, [0, 0, 0])] >>> b.boundary_conditions {'deflection': [(4, [0, 0, 0])], 'slope': [(0, (4, 0, 0))]} Here the deflection of the beam should be ``0`` along all the three axes at ``4``. Similarly, the slope of the beam should be ``4`` along x-axis and ``0`` along y and z axis at ``0``. """ return self._boundary_conditions def apply_load(self, value, start, order, dir="y"): """ This method adds up the force load to a particular beam object. Parameters ========== value : Sympifyable The magnitude of an applied load. dir : String Axis along which load is applied. order : Integer The order of the applied load. - For point loads, order=-1 - For constant distributed load, order=0 - For ramp loads, order=1 - For parabolic ramp loads, order=2 - ... so on. """ x = self.variable value = sympify(value) start = sympify(start) order = sympify(order) if dir == "x": if not order == -1: self._load_vector[0] += value self._load_Singularity[0] += valueSingularityFunction(x, start, order) elif dir == "y": if not order == -1: self._load_vector[1] += value self._load_Singularity[1] += valueSingularityFunction(x, start, order) else: if not order == -1: self._load_vector[2] += value self._load_Singularity[2] += valueSingularityFunction(x, start, order) def apply_moment_load(self, value, start, order, dir="y"): """ This method adds up the moment loads to a particular beam object. Parameters ========== value : Sympifyable The magnitude of an applied moment. dir : String Axis along which moment is applied. order : Integer The order of the applied load. - For point moments, order=-2 - For constant distributed moment, order=-1 - For ramp moments, order=0 - For parabolic ramp moments, order=1 - ... so on. """ x = self.variable value = sympify(value) start = sympify(start) order = sympify(order) if dir == "x": if not order == -2: self._moment_load_vector[0] += value self._load_Singularity[0] += valueSingularityFunction(x, start, order) elif dir == "y": if not order == -2: self._moment_load_vector[1] += value self._load_Singularity[0] += valueSingularityFunction(x, start, order) else: if not order == -2: self._moment_load_vector[2] += value self._load_Singularity[0] += valueSingularityFunction(x, start, order) def apply_support(self, loc, type="fixed"): if type == "pin" or type == "roller": reaction_load = Symbol('R_'+str(loc)) self._reaction_loads[reaction_load] = reaction_load self.bc_deflection.append((loc, [0, 0, 0])) else: reaction_load = Symbol('R_'+str(loc)) reaction_moment = Symbol('M_'+str(loc)) self._reaction_loads[reaction_load] = [reaction_load, reaction_moment] self.bc_deflection.append((loc, [0, 0, 0])) self.bc_slope.append((loc, [0, 0, 0])) def solve_for_reaction_loads(self, reaction): """ Solves for the reaction forces. Examples ======== There is a beam of length 30 meters. It it supported by rollers at of its end. A constant distributed load of magnitude 8 N is applied from start till its end along y-axis. Another linear load having slope equal to 9 is applied along z-axis. >>> from sympy.physics.continuum_mechanics.beam import Beam3D >>> from sympy import symbols >>> l, E, G, I, A, x = symbols('l, E, G, I, A, x') >>> b = Beam3D(30, E, G, I, A, x) >>> b.apply_load(8, start=0, order=0, dir="y") >>> b.apply_load(9x, start=0, order=0, dir="z") >>> b.bc_deflection = [(0, [0, 0, 0]), (30, [0, 0, 0])] >>> R1, R2, R3, R4 = symbols('R1, R2, R3, R4') >>> b.apply_load(R1, start=0, order=-1, dir="y") >>> b.apply_load(R2, start=30, order=-1, dir="y") >>> b.apply_load(R3, start=0, order=-1, dir="z") >>> b.apply_load(R4, start=30, order=-1, dir="z") >>> b.solve_for_reaction_loads(R1, R2, R3, R4) >>> b.reaction_loads {R1: -120, R2: -120, R3: -1350, R4: -2700} """ x = self.variable l=self.length q = self._load_Singularity m = self._moment_load_vector shear_curves = [integrate(load, x) for load in q] moment_curves = [integrate(shear, x) for shear in shear_curves] for i in range(3): react = [r for r in reaction if (shear_curves[i].has(r) or moment_curves[i].has(r))] if len(react) == 0: continue shear_curve = limit(shear_curves[i], x, l) moment_curve = limit(moment_curves[i], x, l) sol = list((linsolve([shear_curve, moment_curve], react).args)[0]) sol_dict = dict(zip(react, sol)) reaction_loads = self._reaction_loads # Check if any of the evaluated rection exists in another direction # and if it exists then it should have same value. for key in sol_dict: if key in reaction_loads and sol_dict[key] != reaction_loads[key]: raise ValueError("Ambiguous solution for %s in different directions." % key) self._reaction_loads.update(sol_dict) def shear_force(self): """ Returns a list of three expressions which represents the shear force curve of the Beam object along all three axes. """ x = self.variable q = self._load_vector m = self._moment_load_vector return [integrate(-q[0], x), integrate(-q[1], x), integrate(-q[2], x)] def axial_force(self): """ Returns expression of Axial shear force present inside the Beam object. """ return self.shear_force()[0] def bending_moment(self): """ Returns a list of three expressions which represents the bending moment curve of the Beam object along all three axes. """ x = self.variable q = self._load_vector m = self._moment_load_vector shear = self.shear_force() return [integrate(-m[0], x), integrate(-m[1] + shear[2], x), integrate(-m[2] - shear[1], x) ] def torsional_moment(): """ Returns expression of Torsional moment present inside the Beam object. """ return self.bending_moment()[0] def solve_slope_deflection(self): from sympy import dsolve, Function, Derivative, Eq x = self.variable l = self.length E = self.elastic_modulus G = self.shear_modulus I = self.second_moment if isinstance(I, list): I_y, I_z = I[0], I[1] else: I_y = I_z = I A = self.area load = self._load_vector moment = self._moment_load_vector defl = Function('defl') theta = Function('theta') # Finding deflection along x-axis(and corresponding slope value by differentiating it) # Equation used: Derivative(EADerivative(def_x(x), x), x) + load_x = 0 eq = Derivative(EADerivative(defl(x), x), x) + load[0] def_x = dsolve(Eq(eq, 0), defl(x)).args[1] # Solving constants originated from dsolve C1 = Symbol('C1') C2 = Symbol('C2') constants = list((linsolve([def_x.subs(x, 0), def_x.subs(x, l)], C1, C2).args)[0]) def_x = def_x.subs({C1:constants[0], C2:constants[1]}) slope_x = def_x.diff(x) self._deflection[0] = def_x self._slope[0] = slope_x # Finding deflection along y-axis and slope across z-axis. System of equation involved: # 1: Derivative(EI_zDerivative(theta_z(x), x), x) + GA(Derivative(defl_y(x), x) - theta_z(x)) + moment_z = 0 # 2: Derivative(GA(Derivative(defl_y(x), x) - theta_z(x)), x) + load_y = 0 C_i = Symbol('C_i') # Substitute value of `GA(Derivative(defl_y(x), x) - theta_z(x))` from (2) in (1) eq1 = Derivative(EI_zDerivative(theta(x), x), x) + (integrate(-load[1], x) + C_i) + moment[2] slope_z = dsolve(Eq(eq1, 0)).args[1] # Solve for constants originated from using dsolve on eq1 constants = list((linsolve([slope_z.subs(x, 0), slope_z.subs(x, l)], C1, C2).args)[0]) slope_z = slope_z.subs({C1:constants[0], C2:constants[1]}) # Put value of slope obtained back in (2) to solve for `C_i` and find deflection across y-axis eq2 = GA(Derivative(defl(x), x)) + load[1]x - C_i - GAslope_z def_y = dsolve(Eq(eq2, 0), defl(x)).args[1] # Solve for constants originated from using dsolve on eq2 constants = list((linsolve([def_y.subs(x, 0), def_y.subs(x, l)], C1, C_i).args)[0]) self._deflection[1] = def_y.subs({C1:constants[0], C_i:constants[1]}) self._slope[2] = slope_z.subs(C_i, constants[1]) # Finding deflection along z-axis and slope across y-axis. System of equation involved: # 1: Derivative(EI_yDerivative(theta_y(x), x), x) - GA(Derivative(defl_z(x), x) + theta_y(x)) + moment_y = 0 # 2: Derivative(GA(Derivative(defl_z(x), x) + theta_y(x)), x) + load_z = 0 # Substitute value of `GA(Derivative(defl_y(x), x) + theta_z(x))` from (2) in (1) eq1 = Derivative(EI_yDerivative(theta(x), x), x) + (integrate(load[2], x) - C_i) + moment[1] slope_y = dsolve(Eq(eq1, 0)).args[1] # Solve for constants originated from using dsolve on eq1 constants = list((linsolve([slope_y.subs(x, 0), slope_y.subs(x, l)], C1, C2).args)[0]) slope_y = slope_y.subs({C1:constants[0], C2:constants[1]}) # Put value of slope obtained back in (2) to solve for `C_i` and find deflection across z-axis eq2 = GA(Derivative(defl(x), x)) + load[2]x - C_i + GA*slope_y def_z = dsolve(Eq(eq2,0)).args[1] # Solve for constants originated from using dsolve on eq2 constants = list((linsolve([def_z.subs(x, 0), def_z.subs(x, l)], C1, C_i).args)[0]) self._deflection[2] = def_z.subs({C1:constants[0], C_i:constants[1]}) self._slope[1] = slope_y.subs(C_i, constants[1]) def slope(self): """ Returns a three element list representing slope of deflection curve along all the three axes. """ return self._slope def deflection(self): """ Returns a three element list representing deflection curve along all the three axes. """ return self._deflection
42437f5e7ba1950bc8227f1993dc5276ed0282a81c698035deeaa00314542445	# -- coding: utf-8 -- from sympy.utilities.pytest import warns_deprecated_sympy from sympy import Rational, S from sympy.physics.units.definitions import c, kg, m, s from sympy.physics.units.dimensions import ( Dimension, DimensionSystem, action, current, length, mass, time, velocity) from sympy.physics.units.quantities import Quantity from sympy.physics.units.unitsystem import UnitSystem from sympy.utilities.pytest import raises def test_definition(): # want to test if the system can have several units of the same dimension dm = Quantity("dm") dm.set_dimension(length) dm.set_scale_factor(Rational(1, 10)) base = (m, s) base_dim = (m.dimension, s.dimension) ms = UnitSystem(base, (c, dm), "MS", "MS system") assert set(ms._base_units) == set(base) assert set(ms._units) == set((m, s, c, dm)) #assert ms._units == DimensionSystem._sort_dims(base + (velocity,)) assert ms.name == "MS" assert ms.descr == "MS system" assert ms._system.base_dims == base_dim assert ms._system.derived_dims == (velocity,) def test_error_definition(): raises(ValueError, lambda: UnitSystem((m, s, c))) def test_str_repr(): assert str(UnitSystem((m, s), name="MS")) == "MS" assert str(UnitSystem((m, s))) == "UnitSystem((meter, second))" assert repr(UnitSystem((m, s))) == "<UnitSystem: (%s, %s)>" % (m, s) def test_print_unit_base(): A = Quantity("A") A.set_dimension(current) A.set_scale_factor(S.One) Js = Quantity("Js") Js.set_dimension(action) Js.set_scale_factor(S.One) mksa = UnitSystem((m, kg, s, A), (Js,)) with warns_deprecated_sympy(): assert mksa.print_unit_base(Js) == m*2kgs*-1 def test_extend(): ms = UnitSystem((m, s), (c,)) Js = Quantity("Js") Js.set_dimension(action) Js.set_scale_factor(1) mks = ms.extend((kg,), (Js,)) res = UnitSystem((m, s, kg), (c, Js)) assert set(mks._base_units) == set(res._base_units) assert set(mks._units) == set(res._units) def test_dim(): dimsys = UnitSystem((m, kg, s), (c,)) assert dimsys.dim == 3 def test_is_consistent(): assert UnitSystem((m, s)).is_consistent is True
96d9ea7f9e2a210e836bf26f60b70b6f6bd0f125ccb63f2c21bfbf79bf4e2ed8	from sympy import Symbol, symbols, S, simplify from sympy.physics.continuum_mechanics.beam import Beam from sympy.functions import SingularityFunction, Piecewise, meijerg, Abs, log from sympy.utilities.pytest import raises from sympy.physics.units import meter, newton, kilo, giga, milli from sympy.physics.continuum_mechanics.beam import Beam3D x = Symbol('x') y = Symbol('y') R1, R2 = symbols('R1, R2') def test_Beam(): E = Symbol('E') E_1 = Symbol('E_1') I = Symbol('I') I_1 = Symbol('I_1') b = Beam(1, E, I) assert b.length == 1 assert b.elastic_modulus == E assert b.second_moment == I assert b.variable == x # Test the length setter b.length = 4 assert b.length == 4 # Test the E setter b.elastic_modulus = E_1 assert b.elastic_modulus == E_1 # Test the I setter b.second_moment = I_1 assert b.second_moment is I_1 # Test the variable setter b.variable = y assert b.variable is y # Test for all boundary conditions. b.bc_deflection = [(0, 2)] b.bc_slope = [(0, 1)] assert b.boundary_conditions == {'deflection': [(0, 2)], 'slope': [(0, 1)]} # Test for slope boundary condition method b.bc_slope.extend([(4, 3), (5, 0)]) s_bcs = b.bc_slope assert s_bcs == [(0, 1), (4, 3), (5, 0)] # Test for deflection boundary condition method b.bc_deflection.extend([(4, 3), (5, 0)]) d_bcs = b.bc_deflection assert d_bcs == [(0, 2), (4, 3), (5, 0)] # Test for updated boundary conditions bcs_new = b.boundary_conditions assert bcs_new == { 'deflection': [(0, 2), (4, 3), (5, 0)], 'slope': [(0, 1), (4, 3), (5, 0)]} b1 = Beam(30, E, I) b1.apply_load(-8, 0, -1) b1.apply_load(R1, 10, -1) b1.apply_load(R2, 30, -1) b1.apply_load(120, 30, -2) b1.bc_deflection = [(10, 0), (30, 0)] b1.solve_for_reaction_loads(R1, R2) # Test for finding reaction forces p = b1.reaction_loads q = {R1: 6, R2: 2} assert p == q # Test for load distribution function. p = b1.load q = -8SingularityFunction(x, 0, -1) + 6SingularityFunction(x, 10, -1) + 120SingularityFunction(x, 30, -2) + 2SingularityFunction(x, 30, -1) assert p == q # Test for shear force distribution function p = b1.shear_force() q = -8SingularityFunction(x, 0, 0) + 6SingularityFunction(x, 10, 0) + 120SingularityFunction(x, 30, -1) + 2SingularityFunction(x, 30, 0) assert p == q # Test for bending moment distribution function p = b1.bending_moment() q = -8SingularityFunction(x, 0, 1) + 6SingularityFunction(x, 10, 1) + 120SingularityFunction(x, 30, 0) + 2SingularityFunction(x, 30, 1) assert p == q # Test for slope distribution function p = b1.slope() q = -4SingularityFunction(x, 0, 2) + 3SingularityFunction(x, 10, 2) + 120SingularityFunction(x, 30, 1) + SingularityFunction(x, 30, 2) + S(4000)/3 assert p == q/(EI) # Test for deflection distribution function p = b1.deflection() q = 4000x/3 - 4SingularityFunction(x, 0, 3)/3 + SingularityFunction(x, 10, 3) + 60SingularityFunction(x, 30, 2) + SingularityFunction(x, 30, 3)/3 - 12000 assert p == q/(EI) # Test using symbols l = Symbol('l') w0 = Symbol('w0') w2 = Symbol('w2') a1 = Symbol('a1') c = Symbol('c') c1 = Symbol('c1') d = Symbol('d') e = Symbol('e') f = Symbol('f') b2 = Beam(l, E, I) b2.apply_load(w0, a1, 1) b2.apply_load(w2, c1, -1) b2.bc_deflection = [(c, d)] b2.bc_slope = [(e, f)] # Test for load distribution function. p = b2.load q = w0SingularityFunction(x, a1, 1) + w2SingularityFunction(x, c1, -1) assert p == q # Test for shear force distribution function p = b2.shear_force() q = w0SingularityFunction(x, a1, 2)/2 + w2SingularityFunction(x, c1, 0) assert p == q # Test for bending moment distribution function p = b2.bending_moment() q = w0SingularityFunction(x, a1, 3)/6 + w2SingularityFunction(x, c1, 1) assert p == q # Test for slope distribution function p = b2.slope() q = (w0SingularityFunction(x, a1, 4)/24 + w2SingularityFunction(x, c1, 2)/2)/(EI) + (EIf - w0SingularityFunction(e, a1, 4)/24 - w2SingularityFunction(e, c1, 2)/2)/(EI) assert p == q # Test for deflection distribution function p = b2.deflection() q = x(EIf - w0SingularityFunction(e, a1, 4)/24 - w2SingularityFunction(e, c1, 2)/2)/(EI) + (w0SingularityFunction(x, a1, 5)/120 + w2SingularityFunction(x, c1, 3)/6)/(EI) + (EI(-cf + d) + cw0SingularityFunction(e, a1, 4)/24 + cw2SingularityFunction(e, c1, 2)/2 - w0SingularityFunction(c, a1, 5)/120 - w2SingularityFunction(c, c1, 3)/6)/(EI) assert p == q b3 = Beam(9, E, I) b3.apply_load(value=-2, start=2, order=2, end=3) b3.bc_slope.append((0, 2)) C3 = symbols('C3') C4 = symbols('C4') p = b3.load q = -2SingularityFunction(x, 2, 2) + 2SingularityFunction(x, 3, 0) + 4SingularityFunction(x, 3, 1) + 2SingularityFunction(x, 3, 2) assert p == q p = b3.slope() q = 2 + (-SingularityFunction(x, 2, 5)/30 + SingularityFunction(x, 3, 3)/3 + SingularityFunction(x, 3, 4)/6 + SingularityFunction(x, 3, 5)/30)/(EI) assert p == q p = b3.deflection() q = 2x + (-SingularityFunction(x, 2, 6)/180 + SingularityFunction(x, 3, 4)/12 + SingularityFunction(x, 3, 5)/30 + SingularityFunction(x, 3, 6)/180)/(EI) assert p == q + C4 b4 = Beam(4, E, I) b4.apply_load(-3, 0, 0, end=3) p = b4.load q = -3SingularityFunction(x, 0, 0) + 3SingularityFunction(x, 3, 0) assert p == q p = b4.slope() q = -3SingularityFunction(x, 0, 3)/6 + 3SingularityFunction(x, 3, 3)/6 assert p == q/(EI) + C3 p = b4.deflection() q = -3SingularityFunction(x, 0, 4)/24 + 3SingularityFunction(x, 3, 4)/24 assert p == q/(EI) + C3x + C4 # can't use end with point loads raises(ValueError, lambda: b4.apply_load(-3, 0, -1, end=3)) with raises(TypeError): b4.variable = 1 def test_insufficient_bconditions(): # Test cases when required number of boundary conditions # are not provided to solve the integration constants. L = symbols('L', positive=True) E, I, P, a3, a4 = symbols('E I P a3 a4') b = Beam(L, E, I, base_char='a') b.apply_load(R2, L, -1) b.apply_load(R1, 0, -1) b.apply_load(-P, L/2, -1) b.solve_for_reaction_loads(R1, R2) p = b.slope() q = PSingularityFunction(x, 0, 2)/4 - PSingularityFunction(x, L/2, 2)/2 + PSingularityFunction(x, L, 2)/4 assert p == q/(EI) + a3 p = b.deflection() q = PSingularityFunction(x, 0, 3)/12 - PSingularityFunction(x, L/2, 3)/6 + PSingularityFunction(x, L, 3)/12 assert p == q/(EI) + a3x + a4 b.bc_deflection = [(0, 0)] p = b.deflection() q = a3x + PSingularityFunction(x, 0, 3)/12 - PSingularityFunction(x, L/2, 3)/6 + PSingularityFunction(x, L, 3)/12 assert p == q/(EI) b.bc_deflection = [(0, 0), (L, 0)] p = b.deflection() q = -L2Px/16 + PSingularityFunction(x, 0, 3)/12 - PSingularityFunction(x, L/2, 3)/6 + PSingularityFunction(x, L, 3)/12 assert p == q/(EI) def test_statically_indeterminate(): E = Symbol('E') I = Symbol('I') M1, M2 = symbols('M1, M2') F = Symbol('F') l = Symbol('l', positive=True) b5 = Beam(l, E, I) b5.bc_deflection = [(0, 0),(l, 0)] b5.bc_slope = [(0, 0),(l, 0)] b5.apply_load(R1, 0, -1) b5.apply_load(M1, 0, -2) b5.apply_load(R2, l, -1) b5.apply_load(M2, l, -2) b5.apply_load(-F, l/2, -1) b5.solve_for_reaction_loads(R1, R2, M1, M2) p = b5.reaction_loads q = {R1: F/2, R2: F/2, M1: -Fl/8, M2: Fl/8} assert p == q def test_beam_units(): E = Symbol('E') I = Symbol('I') R1, R2 = symbols('R1, R2') b = Beam(8meter, 200giganewton/meter*2, 4001000000(millimeter)*4) b.apply_load(5kilonewton, 2meter, -1) b.apply_load(R1, 0meter, -1) b.apply_load(R2, 8meter, -1) b.apply_load(10kilonewton/meter, 4meter, 0, end=8meter) b.bc_deflection = [(0meter, 0meter), (8meter, 0meter)] b.solve_for_reaction_loads(R1, R2) assert b.reaction_loads == {R1: -13750newton, R2: -31250newton} b = Beam(3meter, Enewton/meter*2, Imeter*4) b.apply_load(8kilonewton, 1meter, -1) b.apply_load(R1, 0meter, -1) b.apply_load(R2, 3meter, -1) b.apply_load(12kilonewtonmeter, 2meter, -2) b.bc_deflection = [(0meter, 0meter), (3meter, 0meter)] b.solve_for_reaction_loads(R1, R2) assert b.reaction_loads == {R1: -28000newton/3, R2: 4000newton/3} assert b.deflection().subs(x, 1meter) == 62000meter/(9EI) def test_variable_moment(): E = Symbol('E') I = Symbol('I') b = Beam(4, E, 2(4 - x)) b.apply_load(20, 4, -1) R, M = symbols('R, M') b.apply_load(R, 0, -1) b.apply_load(M, 0, -2) b.bc_deflection = [(0, 0)] b.bc_slope = [(0, 0)] b.solve_for_reaction_loads(R, M) assert b.slope().expand() == ((10xSingularityFunction(x, 0, 0) - 10(x - 4)SingularityFunction(x, 4, 0))/E).expand() assert b.deflection().expand() == ((5x*2SingularityFunction(x, 0, 0) - 10Piecewise((0, Abs(x)/4 < 1), (16meijerg(((3, 1), ()), ((), (2, 0)), x/4), True)) + 40SingularityFunction(x, 4, 1))/E).expand() b = Beam(4, E - x, I) b.apply_load(20, 4, -1) R, M = symbols('R, M') b.apply_load(R, 0, -1) b.apply_load(M, 0, -2) b.bc_deflection = [(0, 0)] b.bc_slope = [(0, 0)] b.solve_for_reaction_loads(R, M) assert b.slope().expand() == ((-80(-log(-E) + log(-E + x))SingularityFunction(x, 0, 0) + 80(-log(-E + 4) + log(-E + x))SingularityFunction(x, 4, 0) + 20(-Elog(-E) + Elog(-E + x) + x)SingularityFunction(x, 0, 0) - 20(-Elog(-E + 4) + Elog(-E + x) + x - 4)SingularityFunction(x, 4, 0))/I).expand() def test_composite_beam(): E = Symbol('E') I = Symbol('I') b1 = Beam(2, E, 1.5I) b2 = Beam(2, E, I) b = b1.join(b2, "fixed") b.apply_load(-20, 0, -1) b.apply_load(80, 0, -2) b.apply_load(20, 4, -1) b.bc_slope = [(0, 0)] b.bc_deflection = [(0, 0)] assert b.length == 4 assert b.second_moment == Piecewise((1.5I, x <= 2), (I, x <= 4)) assert b.slope().subs(x, 4) == 120.0/(EI) assert b.slope().subs(x, 2) == 80.0/(EI) assert int(b.deflection().subs(x, 4).args[0]) == 302 # Coefficient of 1/(EI) l = symbols('l', positive=True) R1, M1, R2, R3, P = symbols('R1 M1 R2 R3 P') b1 = Beam(2l, E, I) b2 = Beam(2l, E, I) b = b1.join(b2,"hinge") b.apply_load(M1, 0, -2) b.apply_load(R1, 0, -1) b.apply_load(R2, l, -1) b.apply_load(R3, 4l, -1) b.apply_load(P, 3l, -1) b.bc_slope = [(0, 0)] b.bc_deflection = [(0, 0), (l, 0), (4l, 0)] b.solve_for_reaction_loads(M1, R1, R2, R3) assert b.reaction_loads == {R3: -P/2, R2: -5P/4, M1: -Pl/4, R1: 3P/4} assert b.slope().subs(x, 3l) == -7Pl2/(48EI) assert b.deflection().subs(x, 2l) == 7Pl*3/(24EI) assert b.deflection().subs(x, 3l) == 5Pl*3/(16EI) # When beams having same second moment are joined. b1 = Beam(2, 500, 10) b2 = Beam(2, 500, 10) b = b1.join(b2, "fixed") b.apply_load(M1, 0, -2) b.apply_load(R1, 0, -1) b.apply_load(R2, 1, -1) b.apply_load(R3, 4, -1) b.apply_load(10, 3, -1) b.bc_slope = [(0, 0)] b.bc_deflection = [(0, 0), (1, 0), (4, 0)] b.solve_for_reaction_loads(M1, R1, R2, R3) assert b.slope() == -2SingularityFunction(x, 0, 1)/5625 + SingularityFunction(x, 0, 2)/1875\ - 133SingularityFunction(x, 1, 2)/135000 + SingularityFunction(x, 3, 2)/1000\ - 37SingularityFunction(x, 4, 2)/67500 assert b.deflection() == -SingularityFunction(x, 0, 2)/5625 + SingularityFunction(x, 0, 3)/5625\ - 133SingularityFunction(x, 1, 3)/405000 + SingularityFunction(x, 3, 3)/3000\ - 37SingularityFunction(x, 4, 3)/202500 def test_point_cflexure(): E = Symbol('E') I = Symbol('I') b = Beam(10, E, I) b.apply_load(-4, 0, -1) b.apply_load(-46, 6, -1) b.apply_load(10, 2, -1) b.apply_load(20, 4, -1) b.apply_load(3, 6, 0) assert b.point_cflexure() == [S(10)/3] def test_remove_load(): E = Symbol('E') I = Symbol('I') b = Beam(4, E, I) try: b.remove_load(2, 1, -1) # As no load is applied on beam, ValueError should be returned. except ValueError: assert True else: assert False b.apply_load(-3, 0, -2) b.apply_load(4, 2, -1) b.apply_load(-2, 2, 2, end = 3) b.remove_load(-2, 2, 2, end = 3) assert b.load == -3SingularityFunction(x, 0, -2) + 4SingularityFunction(x, 2, -1) assert b.applied_loads == [(-3, 0, -2, None), (4, 2, -1, None)] try: b.remove_load(1, 2, -1) # As load of this magnitude was never applied at # this position, method should return a ValueError. except ValueError: assert True else: assert False b.remove_load(-3, 0, -2) b.remove_load(4, 2, -1) assert b.load == 0 assert b.applied_loads == [] def test_apply_support(): E = Symbol('E') I = Symbol('I') b = Beam(4, E, I) b.apply_support(0, "cantilever") b.apply_load(20, 4, -1) M_0, R_0 = symbols('M_0, R_0') b.solve_for_reaction_loads(R_0, M_0) assert b.slope() == (80SingularityFunction(x, 0, 1) - 10SingularityFunction(x, 0, 2) + 10SingularityFunction(x, 4, 2))/(EI) assert b.deflection() == (40SingularityFunction(x, 0, 2) - 10SingularityFunction(x, 0, 3)/3 + 10SingularityFunction(x, 4, 3)/3)/(EI) b = Beam(30, E, I) b.apply_support(10, "pin") b.apply_support(30, "roller") b.apply_load(-8, 0, -1) b.apply_load(120, 30, -2) R_10, R_30 = symbols('R_10, R_30') b.solve_for_reaction_loads(R_10, R_30) assert b.slope() == (-4SingularityFunction(x, 0, 2) + 3SingularityFunction(x, 10, 2) + 120SingularityFunction(x, 30, 1) + SingularityFunction(x, 30, 2) + S(4000)/3)/(EI) assert b.deflection() == (4000x/3 - 4SingularityFunction(x, 0, 3)/3 + SingularityFunction(x, 10, 3) + 60SingularityFunction(x, 30, 2) + SingularityFunction(x, 30, 3)/3 - 12000)/(EI) P = Symbol('P', positive=True) L = Symbol('L', positive=True) b = Beam(L, E, I) b.apply_support(0, type='fixed') b.apply_support(L, type='fixed') b.apply_load(-P, L/2, -1) R_0, R_L, M_0, M_L = symbols('R_0, R_L, M_0, M_L') b.solve_for_reaction_loads(R_0, R_L, M_0, M_L) assert b.reaction_loads == {R_0: P/2, R_L: P/2, M_0: -LP/8, M_L: LP/8} def max_shear_force(self): E = Symbol('E') I = Symbol('I') b = Beam(3, E, I) R, M = symbols('R, M') b.apply_load(R, 0, -1) b.apply_load(M, 0, -2) b.apply_load(2, 3, -1) b.apply_load(4, 2, -1) b.apply_load(2, 2, 0, end=3) b.solve_for_reaction_loads(R, M) assert b.max_shear_force() == (Interval(0, 2), 8) l = symbols('l', positive=True) P = Symbol('P') b = Beam(l, E, I) R1, R2 = symbols('R1, R2') b.apply_load(R1, 0, -1) b.apply_load(R2, l, -1) b.apply_load(P, 0, 0, end=l) b.solve_for_reaction_loads(R1, R2) assert b.max_shear_force() == (0, lAbs(P)/2) def test_max_bmoment(): E = Symbol('E') I = Symbol('I') l, P = symbols('l, P', positive=True) b = Beam(l, E, I) R1, R2 = symbols('R1, R2') b.apply_load(R1, 0, -1) b.apply_load(R2, l, -1) b.apply_load(P, l/2, -1) b.solve_for_reaction_loads(R1, R2) b.reaction_loads assert b.max_bmoment() == (l/2, Pl/4) b = Beam(l, E, I) R1, R2 = symbols('R1, R2') b.apply_load(R1, 0, -1) b.apply_load(R2, l, -1) b.apply_load(P, 0, 0, end=l) b.solve_for_reaction_loads(R1, R2) assert b.max_bmoment() == (l/2, Pl2/8) def test_max_deflection(): E, I, l, F = symbols('E, I, l, F', positive=True) b = Beam(l, E, I) b.bc_deflection = [(0, 0),(l, 0)] b.bc_slope = [(0, 0),(l, 0)] b.apply_load(F/2, 0, -1) b.apply_load(-Fl/8, 0, -2) b.apply_load(F/2, l, -1) b.apply_load(Fl/8, l, -2) b.apply_load(-F, l/2, -1) assert b.max_deflection() == (l/2, Fl*3/(192EI)) def test_Beam3D(): l, E, G, I, A = symbols('l, E, G, I, A') R1, R2, R3, R4 = symbols('R1, R2, R3, R4') b = Beam3D(l, E, G, I, A) m, q = symbols('m, q') b.apply_load(q, 0, 0, dir="y") b.apply_moment_load(m, 0, 0, dir="z") b.bc_slope = [(0, [0, 0, 0]), (l, [0, 0, 0])] b.bc_deflection = [(0, [0, 0, 0]), (l, [0, 0, 0])] b.solve_slope_deflection() assert b.shear_force() == [0, -qx, 0] assert b.bending_moment() == [0, 0, -mx + qx2/2] expected_deflection = (-l2qx*2/(12EI) + l2x*2(AGl(lq - 2m) + 12EIq)/(8EI(AGl2 + 12EI)) + lmx2/(4EI) - lx*3(AGl(lq - 2m) + 12EIq)/(12EI(AGl2 + 12EI)) - mx*3/(6EI) + qx*4/(24EI) + lx(AGl(lq - 2m) + 12EIq)/(2AG(AGl*2 + 12EI)) - qx*2/(2AG) ) dx, dy, dz = b.deflection() assert dx == dz == 0 assert simplify(dy - expected_deflection) == 0 # == doesn't work b2 = Beam3D(30, E, G, I, A, x) b2.apply_load(50, start=0, order=0, dir="y") b2.bc_deflection = [(0, [0, 0, 0]), (30, [0, 0, 0])] b2.apply_load(R1, start=0, order=-1, dir="y") b2.apply_load(R2, start=30, order=-1, dir="y") b2.solve_for_reaction_loads(R1, R2) assert b2.reaction_loads == {R1: -750, R2: -750} b2.solve_slope_deflection() assert b2.slope() == [0, 0, 25x*3/(3EI) - 375x*2/(EI) + 3750x/(EI)] expected_deflection = (25x4/(12EI) - 125x*3/(EI) + 1875x2/(EI) - 25x2/(AG) + 750x/(AG)) dx, dy, dz = b2.deflection() assert dx == dz == 0 assert simplify(dy - expected_deflection) == 0 # == doesn't work # Test for solve_for_reaction_loads b3 = Beam3D(30, E, G, I, A, x) b3.apply_load(8, start=0, order=0, dir="y") b3.apply_load(9x, start=0, order=0, dir="z") b3.apply_load(R1, start=0, order=-1, dir="y") b3.apply_load(R2, start=30, order=-1, dir="y") b3.apply_load(R3, start=0, order=-1, dir="z") b3.apply_load(R4, start=30, order=-1, dir="z") b3.solve_for_reaction_loads(R1, R2, R3, R4) assert b3.reaction_loads == {R1: -120, R2: -120, R3: -1350, R4: -2700} def test_parabolic_loads(): E, I, L = symbols('E, I, L', positive=True, real=True) R, M, P = symbols('R, M, P', real=True) # cantilever beam fixed at x=0 and parabolic distributed loading across # length of beam beam = Beam(L, E, I) beam.bc_deflection.append((0, 0)) beam.bc_slope.append((0, 0)) beam.apply_load(R, 0, -1) beam.apply_load(M, 0, -2) # parabolic load beam.apply_load(1, 0, 2) beam.solve_for_reaction_loads(R, M) assert beam.reaction_loads[R] == -L3 / 3 # cantilever beam fixed at x=0 and parabolic distributed loading across # first half of beam beam = Beam(2 L, E, I) beam.bc_deflection.append((0, 0)) beam.bc_slope.append((0, 0)) beam.apply_load(R, 0, -1) beam.apply_load(M, 0, -2) # parabolic load from x=0 to x=L beam.apply_load(1, 0, 2, end=L) beam.solve_for_reaction_loads(R, M) # result should be the same as the prior example assert beam.reaction_loads[R] == -L*3 / 3 # check constant load beam = Beam(2 L, E, I) beam.apply_load(P, 0, 0, end=L) loading = beam.load.xreplace({L: 10, E: 20, I: 30, P: 40}) assert loading.xreplace({x: 5}) == 40 assert loading.xreplace({x: 15}) == 0 # check ramp load beam = Beam(2 * L, E, I) beam.apply_load(P, 0, 1, end=L) assert beam.load == (PSingularityFunction(x, 0, 1) - PSingularityFunction(x, L, 1) - PLSingularityFunction(x, L, 0)) # check higher order load: x*8 load from x=0 to x=L beam = Beam(2 L, E, I) beam.apply_load(P, 0, 8, end=L) loading = beam.load.xreplace({L: 10, E: 20, I: 30, P: 40}) assert loading.xreplace({x: 5}) == 40 * 5**8 assert loading.xreplace({x: 15}) == 0
52f694fca5d65703c50ad265564d4780a1b13672f51eca9241a9fe136bf600e2	from __future__ import print_function, division from sympy import Basic from sympy.core.compatibility import SYMPY_INTS, Iterable import itertools class NDimArray(object): """ Examples ======== Create an N-dim array of zeros: >>> from sympy import MutableDenseNDimArray >>> a = MutableDenseNDimArray.zeros(2, 3, 4) >>> a [[[0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0]], [[0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0]]] Create an N-dim array from a list; >>> a = MutableDenseNDimArray([[2, 3], [4, 5]]) >>> a [[2, 3], [4, 5]] >>> b = MutableDenseNDimArray([[[1, 2], [3, 4], [5, 6]], [[7, 8], [9, 10], [11, 12]]]) >>> b [[[1, 2], [3, 4], [5, 6]], [[7, 8], [9, 10], [11, 12]]] Create an N-dim array from a flat list with dimension shape: >>> a = MutableDenseNDimArray([1, 2, 3, 4, 5, 6], (2, 3)) >>> a [[1, 2, 3], [4, 5, 6]] Create an N-dim array from a matrix: >>> from sympy import Matrix >>> a = Matrix([[1,2],[3,4]]) >>> a Matrix([ [1, 2], [3, 4]]) >>> b = MutableDenseNDimArray(a) >>> b [[1, 2], [3, 4]] Arithmetic operations on N-dim arrays >>> a = MutableDenseNDimArray([1, 1, 1, 1], (2, 2)) >>> b = MutableDenseNDimArray([4, 4, 4, 4], (2, 2)) >>> c = a + b >>> c [[5, 5], [5, 5]] >>> a - b [[-3, -3], [-3, -3]] """ _diff_wrt = True def __new__(cls, iterable, shape=None, kwargs): from sympy.tensor.array import ImmutableDenseNDimArray return ImmutableDenseNDimArray(iterable, shape, kwargs) def _parse_index(self, index): if isinstance(index, (SYMPY_INTS, Integer)): if index >= self._loop_size: raise ValueError("index out of range") return index if len(index) != self._rank: raise ValueError('Wrong number of array axes') real_index = 0 # check if input index can exist in current indexing for i in range(self._rank): if index[i] >= self.shape[i]: raise ValueError('Index ' + str(index) + ' out of border') real_index = real_indexself.shape[i] + index[i] return real_index def _get_tuple_index(self, integer_index): index = [] for i, sh in enumerate(reversed(self.shape)): index.append(integer_index % sh) integer_index //= sh index.reverse() return tuple(index) def _check_symbolic_index(self, index): # Check if any index is symbolic: tuple_index = (index if isinstance(index, tuple) else (index,)) if any([(isinstance(i, Expr) and (not i.is_number)) for i in tuple_index]): for i, nth_dim in zip(tuple_index, self.shape): if ((i < 0) == True) or ((i >= nth_dim) == True): raise ValueError("index out of range") from sympy.tensor import Indexed return Indexed(self, tuple_index) return None def _setter_iterable_check(self, value): from sympy.matrices.matrices import MatrixBase if isinstance(value, (Iterable, MatrixBase, NDimArray)): raise NotImplementedError @classmethod def _scan_iterable_shape(cls, iterable): def f(pointer): if not isinstance(pointer, Iterable): return [pointer], () result = [] elems, shapes = zip([f(i) for i in pointer]) if len(set(shapes)) != 1: raise ValueError("could not determine shape unambiguously") for i in elems: result.extend(i) return result, (len(shapes),)+shapes[0] return f(iterable) @classmethod def _handle_ndarray_creation_inputs(cls, iterable=None, shape=None, kwargs): from sympy.matrices.matrices import MatrixBase if shape is None and iterable is None: shape = () iterable = () # Construction from another `NDimArray`: elif shape is None and isinstance(iterable, NDimArray): shape = iterable.shape iterable = list(iterable) # Construct N-dim array from an iterable (numpy arrays included): elif shape is None and isinstance(iterable, Iterable): iterable, shape = cls._scan_iterable_shape(iterable) # Construct N-dim array from a Matrix: elif shape is None and isinstance(iterable, MatrixBase): shape = iterable.shape # Construct N-dim array from another N-dim array: elif shape is None and isinstance(iterable, NDimArray): shape = iterable.shape # Construct NDimArray(iterable, shape) elif shape is not None: pass else: shape = () iterable = (iterable,) if isinstance(shape, (SYMPY_INTS, Integer)): shape = (shape,) if any([not isinstance(dim, (SYMPY_INTS, Integer)) for dim in shape]): raise TypeError("Shape should contain integers only.") return tuple(shape), iterable def __len__(self): """Overload common function len(). Returns number of elements in array. Examples ======== >>> from sympy import MutableDenseNDimArray >>> a = MutableDenseNDimArray.zeros(3, 3) >>> a [[0, 0, 0], [0, 0, 0], [0, 0, 0]] >>> len(a) 9 """ return self._loop_size @property def shape(self): """ Returns array shape (dimension). Examples ======== >>> from sympy import MutableDenseNDimArray >>> a = MutableDenseNDimArray.zeros(3, 3) >>> a.shape (3, 3) """ return self._shape def rank(self): """ Returns rank of array. Examples ======== >>> from sympy import MutableDenseNDimArray >>> a = MutableDenseNDimArray.zeros(3,4,5,6,3) >>> a.rank() 5 """ return self._rank def diff(self, args, *kwargs): """ Calculate the derivative of each element in the array. Examples ======== >>> from sympy import ImmutableDenseNDimArray >>> from sympy.abc import x, y >>> M = ImmutableDenseNDimArray([[x, y], [1, xy]]) >>> M.diff(x) [[1, 0], [0, y]] """ from sympy import Derivative kwargs.setdefault('evaluate', True) return Derivative(self.as_immutable(), args, kwargs) def _accept_eval_derivative(self, s): return s._visit_eval_derivative_array(self) def _visit_eval_derivative_scalar(self, base): # Types are (base: scalar, self: array) return self.applyfunc(lambda x: base.diff(x)) def _visit_eval_derivative_array(self, base): # Types are (base: array/matrix, self: array) from sympy import derive_by_array return derive_by_array(base, self) def _eval_derivative_n_times(self, s, n): return Basic._eval_derivative_n_times(self, s, n) def _eval_derivative(self, arg): from sympy import derive_by_array from sympy import Derivative, Tuple from sympy.matrices.common import MatrixCommon if isinstance(arg, (Iterable, Tuple, MatrixCommon, NDimArray)): return derive_by_array(self, arg) else: return self.applyfunc(lambda x: x.diff(arg)) def applyfunc(self, f): """Apply a function to each element of the N-dim array. Examples ======== >>> from sympy import ImmutableDenseNDimArray >>> m = ImmutableDenseNDimArray([i2+j for i in range(2) for j in range(2)], (2, 2)) >>> m [[0, 1], [2, 3]] >>> m.applyfunc(lambda i: 2i) [[0, 2], [4, 6]] """ return type(self)(map(f, self), self.shape) def __str__(self): """Returns string, allows to use standard functions print() and str(). Examples ======== >>> from sympy import MutableDenseNDimArray >>> a = MutableDenseNDimArray.zeros(2, 2) >>> a [[0, 0], [0, 0]] """ def f(sh, shape_left, i, j): if len(shape_left) == 1: return "["+", ".join([str(self[e]) for e in range(i, j)])+"]" sh //= shape_left[0] return "[" + ", ".join([f(sh, shape_left[1:], i+esh, i+(e+1)sh) for e in range(shape_left[0])]) + "]" # + "\n"len(shape_left) if self.rank() == 0: return self[()].__str__() return f(self._loop_size, self.shape, 0, self._loop_size) def __repr__(self): return self.__str__() # We don't define _repr_png_ here because it would add a large amount of # data to any notebook containing SymPy expressions, without adding # anything useful to the notebook. It can still enabled manually, e.g., # for the qtconsole, with init_printing(). def _repr_latex_(self): """ IPython/Jupyter LaTeX printing To change the behavior of this (e.g., pass in some settings to LaTeX), use init_printing(). init_printing() will also enable LaTeX printing for built in numeric types like ints and container types that contain SymPy objects, like lists and dictionaries of expressions. """ from sympy.printing.latex import latex s = latex(self, mode='plain') return "$\\displaystyle %s$" % s _repr_latex_orig = _repr_latex_ def tolist(self): """ Converting MutableDenseNDimArray to one-dim list Examples ======== >>> from sympy import MutableDenseNDimArray >>> a = MutableDenseNDimArray([1, 2, 3, 4], (2, 2)) >>> a [[1, 2], [3, 4]] >>> b = a.tolist() >>> b [[1, 2], [3, 4]] """ def f(sh, shape_left, i, j): if len(shape_left) == 1: return [self[e] for e in range(i, j)] result = [] sh //= shape_left[0] for e in range(shape_left[0]): result.append(f(sh, shape_left[1:], i+esh, i+(e+1)sh)) return result return f(self._loop_size, self.shape, 0, self._loop_size) def __add__(self, other): if not isinstance(other, NDimArray): raise TypeError(str(other)) if self.shape != other.shape: raise ValueError("array shape mismatch") result_list = [i+j for i,j in zip(self, other)] return type(self)(result_list, self.shape) def __sub__(self, other): if not isinstance(other, NDimArray): raise TypeError(str(other)) if self.shape != other.shape: raise ValueError("array shape mismatch") result_list = [i-j for i,j in zip(self, other)] return type(self)(result_list, self.shape) def __mul__(self, other): from sympy.matrices.matrices import MatrixBase if isinstance(other, (Iterable, NDimArray, MatrixBase)): raise ValueError("scalar expected, use tensorproduct(...) for tensorial product") other = sympify(other) result_list = [iother for i in self] return type(self)(result_list, self.shape) def __rmul__(self, other): from sympy.matrices.matrices import MatrixBase if isinstance(other, (Iterable, NDimArray, MatrixBase)): raise ValueError("scalar expected, use tensorproduct(...) for tensorial product") other = sympify(other) result_list = [otheri for i in self] return type(self)(result_list, self.shape) def __div__(self, other): from sympy.matrices.matrices import MatrixBase if isinstance(other, (Iterable, NDimArray, MatrixBase)): raise ValueError("scalar expected") other = sympify(other) result_list = [i/other for i in self] return type(self)(result_list, self.shape) def __rdiv__(self, other): raise NotImplementedError('unsupported operation on NDimArray') def __neg__(self): result_list = [-i for i in self] return type(self)(result_list, self.shape) def __eq__(self, other): """ NDimArray instances can be compared to each other. Instances equal if they have same shape and data. Examples ======== >>> from sympy import MutableDenseNDimArray >>> a = MutableDenseNDimArray.zeros(2, 3) >>> b = MutableDenseNDimArray.zeros(2, 3) >>> a == b True >>> c = a.reshape(3, 2) >>> c == b False >>> a[0,0] = 1 >>> b[0,0] = 2 >>> a == b False """ if not isinstance(other, NDimArray): return False return (self.shape == other.shape) and (list(self) == list(other)) def __ne__(self, other): return not self == other __truediv__ = __div__ __rtruediv__ = __rdiv__ def _eval_transpose(self): if self.rank() != 2: raise ValueError("array rank not 2") from .arrayop import permutedims return permutedims(self, (1, 0)) def transpose(self): return self._eval_transpose() def _eval_conjugate(self): return self.func([i.conjugate() for i in self], self.shape) def conjugate(self): return self._eval_conjugate() def _eval_adjoint(self): return self.transpose().conjugate() def adjoint(self): return self._eval_adjoint() def _slice_expand(self, s, dim): if not isinstance(s, slice): return (s,) start, stop, step = s.indices(dim) return [start + istep for i in range((stop-start)//step)] def _get_slice_data_for_array_access(self, index): sl_factors = [self._slice_expand(i, dim) for (i, dim) in zip(index, self.shape)] eindices = itertools.product(sl_factors) return sl_factors, eindices def _get_slice_data_for_array_assignment(self, index, value): if not isinstance(value, NDimArray): value = type(self)(value) sl_factors, eindices = self._get_slice_data_for_array_access(index) slice_offsets = [min(i) if isinstance(i, list) else None for i in sl_factors] # TODO: add checks for dimensions for `value`? return value, eindices, slice_offsets @classmethod def _check_special_bounds(cls, flat_list, shape): if shape == () and len(flat_list) != 1: raise ValueError("arrays without shape need one scalar value") if shape == (0,) and len(flat_list) > 0: raise ValueError("if array shape is (0,) there cannot be elements") class ImmutableNDimArray(NDimArray, Basic): _op_priority = 11.0 def __hash__(self): return Basic.__hash__(self) def as_immutable(self): return self def as_mutable(self): raise NotImplementedError("abstract method") from sympy.core.numbers import Integer from sympy.core.sympify import sympify from sympy.core.function import Derivative from sympy.core.expr import Expr
796469fbe515aa05e39a77022e4baefd5e190c71489e16d03a358eff69c94c9d	import random from sympy import ( Abs, Add, E, Float, I, Integer, Max, Min, N, Poly, Pow, PurePoly, Rational, S, Symbol, cos, exp, expand_mul, oo, pi, signsimp, simplify, sin, sqrt, symbols, sympify, trigsimp, tan, sstr, diff, Function) from sympy.matrices.matrices import (ShapeError, MatrixError, NonSquareMatrixError, DeferredVector, _find_reasonable_pivot_naive, _simplify) from sympy.matrices import ( GramSchmidt, ImmutableMatrix, ImmutableSparseMatrix, Matrix, SparseMatrix, casoratian, diag, eye, hessian, matrix_multiply_elementwise, ones, randMatrix, rot_axis1, rot_axis2, rot_axis3, wronskian, zeros, MutableDenseMatrix, ImmutableDenseMatrix) from sympy.core.compatibility import long, iterable, range, Hashable from sympy.core import Tuple from sympy.utilities.iterables import flatten, capture from sympy.utilities.pytest import raises, XFAIL, slow, skip, warns_deprecated_sympy from sympy.solvers import solve from sympy.assumptions import Q from sympy.tensor.array import Array from sympy.abc import a, b, c, d, x, y, z, t # don't re-order this list classes = (Matrix, SparseMatrix, ImmutableMatrix, ImmutableSparseMatrix) def test_args(): for c, cls in enumerate(classes): m = cls.zeros(3, 2) # all should give back the same type of arguments, e.g. ints for shape assert m.shape == (3, 2) and all(type(i) is int for i in m.shape) assert m.rows == 3 and type(m.rows) is int assert m.cols == 2 and type(m.cols) is int if not c % 2: assert type(m._mat) in (list, tuple, Tuple) else: assert type(m._smat) is dict def test_division(): v = Matrix(1, 2, [x, y]) assert v.__div__(z) == Matrix(1, 2, [x/z, y/z]) assert v.__truediv__(z) == Matrix(1, 2, [x/z, y/z]) assert v/z == Matrix(1, 2, [x/z, y/z]) def test_sum(): m = Matrix([[1, 2, 3], [x, y, x], [2y, -50, zx]]) assert m + m == Matrix([[2, 4, 6], [2x, 2y, 2x], [4y, -100, 2zx]]) n = Matrix(1, 2, [1, 2]) raises(ShapeError, lambda: m + n) def test_abs(): m = Matrix(1, 2, [-3, x]) n = Matrix(1, 2, [3, Abs(x)]) assert abs(m) == n def test_addition(): a = Matrix(( (1, 2), (3, 1), )) b = Matrix(( (1, 2), (3, 0), )) assert a + b == a.add(b) == Matrix([[2, 4], [6, 1]]) def test_fancy_index_matrix(): for M in (Matrix, SparseMatrix): a = M(3, 3, range(9)) assert a == a[:, :] assert a[1, :] == Matrix(1, 3, [3, 4, 5]) assert a[:, 1] == Matrix([1, 4, 7]) assert a[[0, 1], :] == Matrix([[0, 1, 2], [3, 4, 5]]) assert a[[0, 1], 2] == a[[0, 1], [2]] assert a[2, [0, 1]] == a[[2], [0, 1]] assert a[:, [0, 1]] == Matrix([[0, 1], [3, 4], [6, 7]]) assert a[0, 0] == 0 assert a[0:2, :] == Matrix([[0, 1, 2], [3, 4, 5]]) assert a[:, 0:2] == Matrix([[0, 1], [3, 4], [6, 7]]) assert a[::2, 1] == a[[0, 2], 1] assert a[1, ::2] == a[1, [0, 2]] a = M(3, 3, range(9)) assert a[[0, 2, 1, 2, 1], :] == Matrix([ [0, 1, 2], [6, 7, 8], [3, 4, 5], [6, 7, 8], [3, 4, 5]]) assert a[:, [0,2,1,2,1]] == Matrix([ [0, 2, 1, 2, 1], [3, 5, 4, 5, 4], [6, 8, 7, 8, 7]]) a = SparseMatrix.zeros(3) a[1, 2] = 2 a[0, 1] = 3 a[2, 0] = 4 assert a.extract([1, 1], [2]) == Matrix([ [2], [2]]) assert a.extract([1, 0], [2, 2, 2]) == Matrix([ [2, 2, 2], [0, 0, 0]]) assert a.extract([1, 0, 1, 2], [2, 0, 1, 0]) == Matrix([ [2, 0, 0, 0], [0, 0, 3, 0], [2, 0, 0, 0], [0, 4, 0, 4]]) def test_multiplication(): a = Matrix(( (1, 2), (3, 1), (0, 6), )) b = Matrix(( (1, 2), (3, 0), )) c = ab assert c[0, 0] == 7 assert c[0, 1] == 2 assert c[1, 0] == 6 assert c[1, 1] == 6 assert c[2, 0] == 18 assert c[2, 1] == 0 try: eval('c = a @ b') except SyntaxError: pass else: assert c[0, 0] == 7 assert c[0, 1] == 2 assert c[1, 0] == 6 assert c[1, 1] == 6 assert c[2, 0] == 18 assert c[2, 1] == 0 h = matrix_multiply_elementwise(a, c) assert h == a.multiply_elementwise(c) assert h[0, 0] == 7 assert h[0, 1] == 4 assert h[1, 0] == 18 assert h[1, 1] == 6 assert h[2, 0] == 0 assert h[2, 1] == 0 raises(ShapeError, lambda: matrix_multiply_elementwise(a, b)) c = b Symbol("x") assert isinstance(c, Matrix) assert c[0, 0] == x assert c[0, 1] == 2x assert c[1, 0] == 3x assert c[1, 1] == 0 c2 = x * b assert c == c2 c = 5 * b assert isinstance(c, Matrix) assert c[0, 0] == 5 assert c[0, 1] == 25 assert c[1, 0] == 35 assert c[1, 1] == 0 try: eval('c = 5 @ b') except SyntaxError: pass else: assert isinstance(c, Matrix) assert c[0, 0] == 5 assert c[0, 1] == 25 assert c[1, 0] == 35 assert c[1, 1] == 0 def test_power(): raises(NonSquareMatrixError, lambda: Matrix((1, 2))2) R = Rational A = Matrix([[2, 3], [4, 5]]) assert (A-3)[:] == [R(-269)/8, R(153)/8, R(51)/2, R(-29)/2] assert (A5)[:] == [6140, 8097, 10796, 14237] A = Matrix([[2, 1, 3], [4, 2, 4], [6, 12, 1]]) assert (A3)[:] == [290, 262, 251, 448, 440, 368, 702, 954, 433] assert A0 == eye(3) assert A1 == A assert (Matrix([[2]]) 100)[0, 0] == 2100 assert eye(2)10000000 == eye(2) assert Matrix([[1, 2], [3, 4]])Integer(2) == Matrix([[7, 10], [15, 22]]) A = Matrix([[33, 24], [48, 57]]) assert (A(S(1)/2))[:] == [5, 2, 4, 7] A = Matrix([[0, 4], [-1, 5]]) assert (A(S(1)/2))2 == A assert Matrix([[1, 0], [1, 1]])(S(1)/2) == Matrix([[1, 0], [S.Half, 1]]) assert Matrix([[1, 0], [1, 1]])0.5 == Matrix([[1.0, 0], [0.5, 1.0]]) from sympy.abc import a, b, n assert Matrix([[1, a], [0, 1]])n == Matrix([[1, an], [0, 1]]) assert Matrix([[b, a], [0, b]])n == Matrix([[bn, ab*(n-1)n], [0, bn]]) assert Matrix([[a, 1, 0], [0, a, 1], [0, 0, a]])n == Matrix([ [an, a(n-1)n, a(n-2)(n-1)n/2], [0, an, a(n-1)n], [0, 0, an]]) assert Matrix([[a, 1, 0], [0, a, 0], [0, 0, b]])n == Matrix([ [an, a(n-1)n, 0], [0, an, 0], [0, 0, bn]]) A = Matrix([[1, 0], [1, 7]]) assert A._matrix_pow_by_jordan_blocks(3) == A._eval_pow_by_recursion(3) A = Matrix([[2]]) assert A10 == Matrix([[210]]) == A._matrix_pow_by_jordan_blocks(10) == \ A._eval_pow_by_recursion(10) # testing a matrix that cannot be jordan blocked issue 11766 m = Matrix([[3, 0, 0, 0, -3], [0, -3, -3, 0, 3], [0, 3, 0, 3, 0], [0, 0, 3, 0, 3], [3, 0, 0, 3, 0]]) raises(MatrixError, lambda: m._matrix_pow_by_jordan_blocks(10)) # test issue 11964 raises(ValueError, lambda: Matrix([[1, 1], [3, 3]])._matrix_pow_by_jordan_blocks(-10)) A = Matrix([[0, 1, 0], [0, 0, 1], [0, 0, 0]]) # Nilpotent jordan block size 3 assert A10.0 == Matrix([[0, 0, 0], [0, 0, 0], [0, 0, 0]]) raises(ValueError, lambda: A2.1) raises(ValueError, lambda: A(S(3)/2)) A = Matrix([[8, 1], [3, 2]]) assert A10.0 == Matrix([[1760744107, 272388050], [817164150, 126415807]]) A = Matrix([[0, 0, 1], [0, 0, 1], [0, 0, 1]]) # Nilpotent jordan block size 1 assert A10.2 == Matrix([[0, 0, 1], [0, 0, 1], [0, 0, 1]]) A = Matrix([[0, 1, 0], [0, 0, 1], [0, 0, 1]]) # Nilpotent jordan block size 2 assert A10.0 == Matrix([[0, 0, 1], [0, 0, 1], [0, 0, 1]]) n = Symbol('n', integer=True) raises(ValueError, lambda: An) n = Symbol('n', integer=True, nonnegative=True) raises(ValueError, lambda: An) assert A(n + 2) == Matrix([[0, 0, 1], [0, 0, 1], [0, 0, 1]]) raises(ValueError, lambda: A(S(3)/2)) A = Matrix([[0, 0, 1], [3, 0, 1], [4, 3, 1]]) assert A5.0 == Matrix([[168, 72, 89], [291, 144, 161], [572, 267, 329]]) assert A5.0 == A5 def test_creation(): raises(ValueError, lambda: Matrix(5, 5, range(20))) raises(ValueError, lambda: Matrix(5, -1, [])) raises(IndexError, lambda: Matrix((1, 2))[2]) with raises(IndexError): Matrix((1, 2))[1:2] = 5 with raises(IndexError): Matrix((1, 2))[3] = 5 assert Matrix() == Matrix([]) == Matrix([[]]) == Matrix(0, 0, []) a = Matrix([[x, 0], [0, 0]]) m = a assert m.cols == m.rows assert m.cols == 2 assert m[:] == [x, 0, 0, 0] b = Matrix(2, 2, [x, 0, 0, 0]) m = b assert m.cols == m.rows assert m.cols == 2 assert m[:] == [x, 0, 0, 0] assert a == b assert Matrix(b) == b c = Matrix(( Matrix(( (1, 2, 3), (4, 5, 6) )), (7, 8, 9) )) assert c.cols == 3 assert c.rows == 3 assert c[:] == [1, 2, 3, 4, 5, 6, 7, 8, 9] assert Matrix(eye(2)) == eye(2) assert ImmutableMatrix(ImmutableMatrix(eye(2))) == ImmutableMatrix(eye(2)) assert ImmutableMatrix(c) == c.as_immutable() assert Matrix(ImmutableMatrix(c)) == ImmutableMatrix(c).as_mutable() assert c is not Matrix(c) def test_tolist(): lst = [[S.One, S.Half, xy, S.Zero], [x, y, z, x*2], [y, -S.One, zx, 3]] m = Matrix(lst) assert m.tolist() == lst def test_as_mutable(): assert zeros(0, 3).as_mutable() == zeros(0, 3) assert zeros(0, 3).as_immutable() == ImmutableMatrix(zeros(0, 3)) assert zeros(3, 0).as_immutable() == ImmutableMatrix(zeros(3, 0)) def test_determinant(): for M in [Matrix(), Matrix([[1]])]: assert ( M.det() == M._eval_det_bareiss() == M._eval_det_berkowitz() == M._eval_det_lu() == 1) M = Matrix(( (-3, 2), ( 8, -5) )) assert M.det(method="bareiss") == -1 assert M.det(method="berkowitz") == -1 assert M.det(method="lu") == -1 M = Matrix(( (x, 1), (y, 2y) )) assert M.det(method="bareiss") == 2xy - y assert M.det(method="berkowitz") == 2xy - y assert M.det(method="lu") == 2xy - y M = Matrix(( (1, 1, 1), (1, 2, 3), (1, 3, 6) )) assert M.det(method="bareiss") == 1 assert M.det(method="berkowitz") == 1 assert M.det(method="lu") == 1 M = Matrix(( ( 3, -2, 0, 5), (-2, 1, -2, 2), ( 0, -2, 5, 0), ( 5, 0, 3, 4) )) assert M.det(method="bareiss") == -289 assert M.det(method="berkowitz") == -289 assert M.det(method="lu") == -289 M = Matrix(( ( 1, 2, 3, 4), ( 5, 6, 7, 8), ( 9, 10, 11, 12), (13, 14, 15, 16) )) assert M.det(method="bareiss") == 0 assert M.det(method="berkowitz") == 0 assert M.det(method="lu") == 0 M = Matrix(( (3, 2, 0, 0, 0), (0, 3, 2, 0, 0), (0, 0, 3, 2, 0), (0, 0, 0, 3, 2), (2, 0, 0, 0, 3) )) assert M.det(method="bareiss") == 275 assert M.det(method="berkowitz") == 275 assert M.det(method="lu") == 275 M = Matrix(( (1, 0, 1, 2, 12), (2, 0, 1, 1, 4), (2, 1, 1, -1, 3), (3, 2, -1, 1, 8), (1, 1, 1, 0, 6) )) assert M.det(method="bareiss") == -55 assert M.det(method="berkowitz") == -55 assert M.det(method="lu") == -55 M = Matrix(( (-5, 2, 3, 4, 5), ( 1, -4, 3, 4, 5), ( 1, 2, -3, 4, 5), ( 1, 2, 3, -2, 5), ( 1, 2, 3, 4, -1) )) assert M.det(method="bareiss") == 11664 assert M.det(method="berkowitz") == 11664 assert M.det(method="lu") == 11664 M = Matrix(( ( 2, 7, -1, 3, 2), ( 0, 0, 1, 0, 1), (-2, 0, 7, 0, 2), (-3, -2, 4, 5, 3), ( 1, 0, 0, 0, 1) )) assert M.det(method="bareiss") == 123 assert M.det(method="berkowitz") == 123 assert M.det(method="lu") == 123 M = Matrix(( (x, y, z), (1, 0, 0), (y, z, x) )) assert M.det(method="bareiss") == z2 - xy assert M.det(method="berkowitz") == z*2 - xy assert M.det(method="lu") == z*2 - xy # issue 13835 a = symbols('a') M = lambda n: Matrix([[i + aj for i in range(n)] for j in range(n)]) assert M(5).det() == 0 assert M(6).det() == 0 assert M(7).det() == 0 def test_slicing(): m0 = eye(4) assert m0[:3, :3] == eye(3) assert m0[2:4, 0:2] == zeros(2) m1 = Matrix(3, 3, lambda i, j: i + j) assert m1[0, :] == Matrix(1, 3, (0, 1, 2)) assert m1[1:3, 1] == Matrix(2, 1, (2, 3)) m2 = Matrix([[0, 1, 2, 3], [4, 5, 6, 7], [8, 9, 10, 11], [12, 13, 14, 15]]) assert m2[:, -1] == Matrix(4, 1, [3, 7, 11, 15]) assert m2[-2:, :] == Matrix([[8, 9, 10, 11], [12, 13, 14, 15]]) def test_submatrix_assignment(): m = zeros(4) m[2:4, 2:4] = eye(2) assert m == Matrix(((0, 0, 0, 0), (0, 0, 0, 0), (0, 0, 1, 0), (0, 0, 0, 1))) m[:2, :2] = eye(2) assert m == eye(4) m[:, 0] = Matrix(4, 1, (1, 2, 3, 4)) assert m == Matrix(((1, 0, 0, 0), (2, 1, 0, 0), (3, 0, 1, 0), (4, 0, 0, 1))) m[:, :] = zeros(4) assert m == zeros(4) m[:, :] = [(1, 2, 3, 4), (5, 6, 7, 8), (9, 10, 11, 12), (13, 14, 15, 16)] assert m == Matrix(((1, 2, 3, 4), (5, 6, 7, 8), (9, 10, 11, 12), (13, 14, 15, 16))) m[:2, 0] = [0, 0] assert m == Matrix(((0, 2, 3, 4), (0, 6, 7, 8), (9, 10, 11, 12), (13, 14, 15, 16))) def test_extract(): m = Matrix(4, 3, lambda i, j: i3 + j) assert m.extract([0, 1, 3], [0, 1]) == Matrix(3, 2, [0, 1, 3, 4, 9, 10]) assert m.extract([0, 3], [0, 0, 2]) == Matrix(2, 3, [0, 0, 2, 9, 9, 11]) assert m.extract(range(4), range(3)) == m raises(IndexError, lambda: m.extract([4], [0])) raises(IndexError, lambda: m.extract([0], [3])) def test_reshape(): m0 = eye(3) assert m0.reshape(1, 9) == Matrix(1, 9, (1, 0, 0, 0, 1, 0, 0, 0, 1)) m1 = Matrix(3, 4, lambda i, j: i + j) assert m1.reshape( 4, 3) == Matrix(((0, 1, 2), (3, 1, 2), (3, 4, 2), (3, 4, 5))) assert m1.reshape(2, 6) == Matrix(((0, 1, 2, 3, 1, 2), (3, 4, 2, 3, 4, 5))) def test_applyfunc(): m0 = eye(3) assert m0.applyfunc(lambda x: 2x) == eye(3)2 assert m0.applyfunc(lambda x: 0) == zeros(3) def test_expand(): m0 = Matrix([[x(x + y), 2], [((x + y)y)x, x(y + x(x + y))]]) # Test if expand() returns a matrix m1 = m0.expand() assert m1 == Matrix( [[xy + x*2, 2], [xy*2 + yx*2, xy + yx2 + x3]]) a = Symbol('a', real=True) assert Matrix([exp(Ia)]).expand(complex=True) == \ Matrix([cos(a) + Isin(a)]) assert Matrix([[0, 1, 2], [0, 0, -1], [0, 0, 0]]).exp() == Matrix([ [1, 1, Rational(3, 2)], [0, 1, -1], [0, 0, 1]] ) def test_refine(): m0 = Matrix([[Abs(x)2, sqrt(x2)], [sqrt(x2)Abs(y)2, sqrt(y2)Abs(x)2]]) m1 = m0.refine(Q.real(x) & Q.real(y)) assert m1 == Matrix([[x2, Abs(x)], [y2Abs(x), x*2Abs(y)]]) m1 = m0.refine(Q.positive(x) & Q.positive(y)) assert m1 == Matrix([[x*2, x], [xy2, x2y]]) m1 = m0.refine(Q.negative(x) & Q.negative(y)) assert m1 == Matrix([[x2, -x], [-xy2, -x2y]]) def test_random(): M = randMatrix(3, 3) M = randMatrix(3, 3, seed=3) assert M == randMatrix(3, 3, seed=3) M = randMatrix(3, 4, 0, 150) M = randMatrix(3, seed=4, symmetric=True) assert M == randMatrix(3, seed=4, symmetric=True) S = M.copy() S.simplify() assert S == M # doesn't fail when elements are Numbers, not int rng = random.Random(4) assert M == randMatrix(3, symmetric=True, prng=rng) # Ensure symmetry for size in (10, 11): # Test odd and even for percent in (100, 70, 30): M = randMatrix(size, symmetric=True, percent=percent, prng=rng) assert M == M.T M = randMatrix(10, min=1, percent=70) zero_count = 0 for i in range(M.shape[0]): for j in range(M.shape[1]): if M[i, j] == 0: zero_count += 1 assert zero_count == 30 def test_LUdecomp(): testmat = Matrix([[0, 2, 5, 3], [3, 3, 7, 4], [8, 4, 0, 2], [-2, 6, 3, 4]]) L, U, p = testmat.LUdecomposition() assert L.is_lower assert U.is_upper assert (LU).permute_rows(p, 'backward') - testmat == zeros(4) testmat = Matrix([[6, -2, 7, 4], [0, 3, 6, 7], [1, -2, 7, 4], [-9, 2, 6, 3]]) L, U, p = testmat.LUdecomposition() assert L.is_lower assert U.is_upper assert (LU).permute_rows(p, 'backward') - testmat == zeros(4) # non-square testmat = Matrix([[1, 2, 3], [4, 5, 6], [7, 8, 9], [10, 11, 12]]) L, U, p = testmat.LUdecomposition(rankcheck=False) assert L.is_lower assert U.is_upper assert (LU).permute_rows(p, 'backward') - testmat == zeros(4, 3) # square and singular testmat = Matrix([[1, 2, 3], [2, 4, 6], [4, 5, 6]]) L, U, p = testmat.LUdecomposition(rankcheck=False) assert L.is_lower assert U.is_upper assert (LU).permute_rows(p, 'backward') - testmat == zeros(3) M = Matrix(((1, x, 1), (2, y, 0), (y, 0, z))) L, U, p = M.LUdecomposition() assert L.is_lower assert U.is_upper assert (LU).permute_rows(p, 'backward') - M == zeros(3) mL = Matrix(( (1, 0, 0), (2, 3, 0), )) assert mL.is_lower is True assert mL.is_upper is False mU = Matrix(( (1, 2, 3), (0, 4, 5), )) assert mU.is_lower is False assert mU.is_upper is True # test FF LUdecomp M = Matrix([[1, 3, 3], [3, 2, 6], [3, 2, 2]]) P, L, Dee, U = M.LUdecompositionFF() assert PM == LDee.inv()U M = Matrix([[1, 2, 3, 4], [3, -1, 2, 3], [3, 1, 3, -2], [6, -1, 0, 2]]) P, L, Dee, U = M.LUdecompositionFF() assert PM == LDee.inv()U M = Matrix([[0, 0, 1], [2, 3, 0], [3, 1, 4]]) P, L, Dee, U = M.LUdecompositionFF() assert PM == LDee.inv()U def test_LUsolve(): A = Matrix([[2, 3, 5], [3, 6, 2], [8, 3, 6]]) x = Matrix(3, 1, [3, 7, 5]) b = Ax soln = A.LUsolve(b) assert soln == x A = Matrix([[0, -1, 2], [5, 10, 7], [8, 3, 4]]) x = Matrix(3, 1, [-1, 2, 5]) b = Ax soln = A.LUsolve(b) assert soln == x A = Matrix([[2, 1], [1, 0], [1, 0]]) # issue 14548 b = Matrix([3, 1, 1]) assert A.LUsolve(b) == Matrix([1, 1]) b = Matrix([3, 1, 2]) # inconsistent raises(ValueError, lambda: A.LUsolve(b)) A = Matrix([[0, -1, 2], [5, 10, 7], [8, 3, 4], [2, 3, 5], [3, 6, 2], [8, 3, 6]]) x = Matrix([2, 1, -4]) b = Ax soln = A.LUsolve(b) assert soln == x A = Matrix([[0, -1, 2], [5, 10, 7]]) # underdetermined x = Matrix([-1, 2, 0]) b = Ax raises(NotImplementedError, lambda: A.LUsolve(b)) def test_QRsolve(): A = Matrix([[2, 3, 5], [3, 6, 2], [8, 3, 6]]) x = Matrix(3, 1, [3, 7, 5]) b = Ax soln = A.QRsolve(b) assert soln == x x = Matrix([[1, 2], [3, 4], [5, 6]]) b = Ax soln = A.QRsolve(b) assert soln == x A = Matrix([[0, -1, 2], [5, 10, 7], [8, 3, 4]]) x = Matrix(3, 1, [-1, 2, 5]) b = Ax soln = A.QRsolve(b) assert soln == x x = Matrix([[7, 8], [9, 10], [11, 12]]) b = Ax soln = A.QRsolve(b) assert soln == x def test_inverse(): A = eye(4) assert A.inv() == eye(4) assert A.inv(method="LU") == eye(4) assert A.inv(method="ADJ") == eye(4) A = Matrix([[2, 3, 5], [3, 6, 2], [8, 3, 6]]) Ainv = A.inv() assert AAinv == eye(3) assert A.inv(method="LU") == Ainv assert A.inv(method="ADJ") == Ainv # test that immutability is not a problem cls = ImmutableMatrix m = cls([[48, 49, 31], [ 9, 71, 94], [59, 28, 65]]) assert all(type(m.inv(s)) is cls for s in 'GE ADJ LU'.split()) cls = ImmutableSparseMatrix m = cls([[48, 49, 31], [ 9, 71, 94], [59, 28, 65]]) assert all(type(m.inv(s)) is cls for s in 'CH LDL'.split()) def test_matrix_inverse_mod(): A = Matrix(2, 1, [1, 0]) raises(NonSquareMatrixError, lambda: A.inv_mod(2)) A = Matrix(2, 2, [1, 0, 0, 0]) raises(ValueError, lambda: A.inv_mod(2)) A = Matrix(2, 2, [1, 2, 3, 4]) Ai = Matrix(2, 2, [1, 1, 0, 1]) assert A.inv_mod(3) == Ai A = Matrix(2, 2, [1, 0, 0, 1]) assert A.inv_mod(2) == A A = Matrix(3, 3, [1, 2, 3, 4, 5, 6, 7, 8, 9]) raises(ValueError, lambda: A.inv_mod(5)) A = Matrix(3, 3, [5, 1, 3, 2, 6, 0, 2, 1, 1]) Ai = Matrix(3, 3, [6, 8, 0, 1, 5, 6, 5, 6, 4]) assert A.inv_mod(9) == Ai A = Matrix(3, 3, [1, 6, -3, 4, 1, -5, 3, -5, 5]) Ai = Matrix(3, 3, [4, 3, 3, 1, 2, 5, 1, 5, 1]) assert A.inv_mod(6) == Ai A = Matrix(3, 3, [1, 6, 1, 4, 1, 5, 3, 2, 5]) Ai = Matrix(3, 3, [6, 0, 3, 6, 6, 4, 1, 6, 1]) assert A.inv_mod(7) == Ai def test_util(): R = Rational v1 = Matrix(1, 3, [1, 2, 3]) v2 = Matrix(1, 3, [3, 4, 5]) assert v1.norm() == sqrt(14) assert v1.project(v2) == Matrix(1, 3, [R(39)/25, R(52)/25, R(13)/5]) assert Matrix.zeros(1, 2) == Matrix(1, 2, [0, 0]) assert ones(1, 2) == Matrix(1, 2, [1, 1]) assert v1.copy() == v1 # cofactor assert eye(3) == eye(3).cofactor_matrix() test = Matrix([[1, 3, 2], [2, 6, 3], [2, 3, 6]]) assert test.cofactor_matrix() == \ Matrix([[27, -6, -6], [-12, 2, 3], [-3, 1, 0]]) test = Matrix([[1, 2, 3], [4, 5, 6], [7, 8, 9]]) assert test.cofactor_matrix() == \ Matrix([[-3, 6, -3], [6, -12, 6], [-3, 6, -3]]) def test_jacobian_hessian(): L = Matrix(1, 2, [x*2y, 2y2 + xy]) syms = [x, y] assert L.jacobian(syms) == Matrix([[2xy, x*2], [y, 4y + x]]) L = Matrix(1, 2, [x, x*2y*3]) assert L.jacobian(syms) == Matrix([[1, 0], [2xy3, x23y2]]) f = x2y syms = [x, y] assert hessian(f, syms) == Matrix([[2y, 2x], [2x, 0]]) f = x2y*3 assert hessian(f, syms) == \ Matrix([[2y*3, 6xy2], [6xy2, 6x*2y]]) f = z + xy2 g = x2 + 2y*3 ans = Matrix([[0, 2y], [2y, 2x]]) assert ans == hessian(f, Matrix([x, y])) assert ans == hessian(f, Matrix([x, y]).T) assert hessian(f, (y, x), [g]) == Matrix([ [ 0, 6y2, 2x], [6y2, 2x, 2y], [ 2x, 2y, 0]]) def test_QR(): A = Matrix([[1, 2], [2, 3]]) Q, S = A.QRdecomposition() R = Rational assert Q == Matrix([ [ 5R(-1, 2), (R(2)/5)(R(1)/5)*R(-1, 2)], [25*R(-1, 2), (-R(1)/5)(R(1)/5)R(-1, 2)]]) assert S == Matrix([[5R(1, 2), 85R(-1, 2)], [0, (R(1)/5)R(1, 2)]]) assert QS == A assert Q.T * Q == eye(2) A = Matrix([[1, 1, 1], [1, 1, 3], [2, 3, 4]]) Q, R = A.QRdecomposition() assert Q.T * Q == eye(Q.cols) assert R.is_upper assert A == QR def test_QR_non_square(): # Narrow (cols < rows) matrices A = Matrix([[9, 0, 26], [12, 0, -7], [0, 4, 4], [0, -3, -3]]) Q, R = A.QRdecomposition() assert Q.T Q == eye(Q.cols) assert R.is_upper assert A == QR A = Matrix([[1, -1, 4], [1, 4, -2], [1, 4, 2], [1, -1, 0]]) Q, R = A.QRdecomposition() assert Q.T Q == eye(Q.cols) assert R.is_upper assert A == QR A = Matrix(2, 1, [1, 2]) Q, R = A.QRdecomposition() assert Q.T Q == eye(Q.cols) assert R.is_upper assert A == QR # Wide (cols > rows) matrices A = Matrix([[1, 2, 3], [4, 5, 6]]) Q, R = A.QRdecomposition() assert Q.T Q == eye(Q.cols) assert R.is_upper assert A == QR A = Matrix([[1, 2, 3, 4], [1, 4, 9, 16], [1, 8, 27, 64]]) Q, R = A.QRdecomposition() assert Q.T Q == eye(Q.cols) assert R.is_upper assert A == QR A = Matrix(1, 2, [1, 2]) Q, R = A.QRdecomposition() assert Q.T Q == eye(Q.cols) assert R.is_upper assert A == QR def test_QR_trivial(): # Rank deficient matrices A = Matrix([[1, 2, 3], [4, 5, 6], [7, 8, 9]]) Q, R = A.QRdecomposition() assert Q.T Q == eye(Q.cols) assert R.is_upper assert A == QR A = Matrix([[1, 1, 1], [2, 2, 2], [3, 3, 3], [4, 4, 4]]) Q, R = A.QRdecomposition() assert Q.T Q == eye(Q.cols) assert R.is_upper assert A == QR A = Matrix([[1, 1, 1], [2, 2, 2], [3, 3, 3], [4, 4, 4]]).T Q, R = A.QRdecomposition() assert Q.T Q == eye(Q.cols) assert R.is_upper assert A == QR # Zero rank matrices A = Matrix([[0, 0, 0]]) Q, R = A.QRdecomposition() assert Q.T Q == eye(Q.cols) assert R.is_upper assert A == QR A = Matrix([[0, 0, 0]]).T Q, R = A.QRdecomposition() assert Q.T Q == eye(Q.cols) assert R.is_upper assert A == QR A = Matrix([[0, 0, 0], [0, 0, 0]]) Q, R = A.QRdecomposition() assert Q.T Q == eye(Q.cols) assert R.is_upper assert A == QR A = Matrix([[0, 0, 0], [0, 0, 0]]).T Q, R = A.QRdecomposition() assert Q.T Q == eye(Q.cols) assert R.is_upper assert A == QR # Rank deficient matrices with zero norm from beginning columns A = Matrix([[0, 0, 0], [1, 2, 3]]).T Q, R = A.QRdecomposition() assert Q.T Q == eye(Q.cols) assert R.is_upper assert A == QR A = Matrix([[0, 0, 0, 0], [1, 2, 3, 4], [0, 0, 0, 0]]).T Q, R = A.QRdecomposition() assert Q.T Q == eye(Q.cols) assert R.is_upper assert A == QR A = Matrix([[0, 0, 0, 0], [1, 2, 3, 4], [0, 0, 0, 0], [2, 4, 6, 8]]).T Q, R = A.QRdecomposition() assert Q.T Q == eye(Q.cols) assert R.is_upper assert A == QR A = Matrix([[0, 0, 0], [0, 0, 0], [0, 0, 0], [1, 2, 3]]).T Q, R = A.QRdecomposition() assert Q.T Q == eye(Q.cols) assert R.is_upper assert A == QR def test_nullspace(): # first test reduced row-ech form R = Rational M = Matrix([[5, 7, 2, 1], [1, 6, 2, -1]]) out, tmp = M.rref() assert out == Matrix([[1, 0, -R(2)/23, R(13)/23], [0, 1, R(8)/23, R(-6)/23]]) M = Matrix([[-5, -1, 4, -3, -1], [ 1, -1, -1, 1, 0], [-1, 0, 0, 0, 0], [ 4, 1, -4, 3, 1], [-2, 0, 2, -2, -1]]) assert MM.nullspace()[0] == Matrix(5, 1, [0]5) M = Matrix([[ 1, 3, 0, 2, 6, 3, 1], [-2, -6, 0, -2, -8, 3, 1], [ 3, 9, 0, 0, 6, 6, 2], [-1, -3, 0, 1, 0, 9, 3]]) out, tmp = M.rref() assert out == Matrix([[1, 3, 0, 0, 2, 0, 0], [0, 0, 0, 1, 2, 0, 0], [0, 0, 0, 0, 0, 1, R(1)/3], [0, 0, 0, 0, 0, 0, 0]]) # now check the vectors basis = M.nullspace() assert basis[0] == Matrix([-3, 1, 0, 0, 0, 0, 0]) assert basis[1] == Matrix([0, 0, 1, 0, 0, 0, 0]) assert basis[2] == Matrix([-2, 0, 0, -2, 1, 0, 0]) assert basis[3] == Matrix([0, 0, 0, 0, 0, R(-1)/3, 1]) # issue 4797; just see that we can do it when rows > cols M = Matrix([[1, 2], [2, 4], [3, 6]]) assert M.nullspace() def test_columnspace(): M = Matrix([[ 1, 2, 0, 2, 5], [-2, -5, 1, -1, -8], [ 0, -3, 3, 4, 1], [ 3, 6, 0, -7, 2]]) # now check the vectors basis = M.columnspace() assert basis[0] == Matrix([1, -2, 0, 3]) assert basis[1] == Matrix([2, -5, -3, 6]) assert basis[2] == Matrix([2, -1, 4, -7]) #check by columnspace definition a, b, c, d, e = symbols('a b c d e') X = Matrix([a, b, c, d, e]) for i in range(len(basis)): eq=MX-basis[i] assert len(solve(eq, X)) != 0 #check if rank-nullity theorem holds assert M.rank() == len(basis) assert len(M.nullspace()) + len(M.columnspace()) == M.cols def test_wronskian(): assert wronskian([cos(x), sin(x)], x) == cos(x)2 + sin(x)2 assert wronskian([exp(x), exp(2x)], x) == exp(3x) assert wronskian([exp(x), x], x) == exp(x) - xexp(x) assert wronskian([1, x, x2], x) == 2 w1 = -6exp(x)sin(x)x + 6cos(x)exp(x)x2 - 6exp(x)cos(x)x - \ exp(x)cos(x)x*3 + exp(x)sin(x)x3 assert wronskian([exp(x), cos(x), x3], x).expand() == w1 assert wronskian([exp(x), cos(x), x3], x, method='berkowitz').expand() \ == w1 w2 = -x3cos(x)2 - x3sin(x)2 - 6xcos(x)2 - 6xsin(x)2 assert wronskian([sin(x), cos(x), x3], x).expand() == w2 assert wronskian([sin(x), cos(x), x3], x, method='berkowitz').expand() \ == w2 assert wronskian([], x) == 1 def test_eigen(): R = Rational assert eye(3).charpoly(x) == Poly((x - 1)3, x) assert eye(3).charpoly(y) == Poly((y - 1)3, y) M = Matrix([[1, 0, 0], [0, 1, 0], [0, 0, 1]]) assert M.eigenvals(multiple=False) == {S.One: 3} assert M.eigenvals(multiple=True) == [1, 1, 1] assert M.eigenvects() == ( [(1, 3, [Matrix([1, 0, 0]), Matrix([0, 1, 0]), Matrix([0, 0, 1])])]) assert M.left_eigenvects() == ( [(1, 3, [Matrix([[1, 0, 0]]), Matrix([[0, 1, 0]]), Matrix([[0, 0, 1]])])]) M = Matrix([[0, 1, 1], [1, 0, 0], [1, 1, 1]]) assert M.eigenvals() == {2S.One: 1, -S.One: 1, S.Zero: 1} assert M.eigenvects() == ( [ (-1, 1, [Matrix([-1, 1, 0])]), ( 0, 1, [Matrix([0, -1, 1])]), ( 2, 1, [Matrix([R(2, 3), R(1, 3), 1])]) ]) assert M.left_eigenvects() == ( [ (-1, 1, [Matrix([[-2, 1, 1]])]), (0, 1, [Matrix([[-1, -1, 1]])]), (2, 1, [Matrix([[1, 1, 1]])]) ]) a = Symbol('a') M = Matrix([[a, 0], [0, 1]]) assert M.eigenvals() == {a: 1, S.One: 1} M = Matrix([[1, -1], [1, 3]]) assert M.eigenvects() == ([(2, 2, [Matrix(2, 1, [-1, 1])])]) assert M.left_eigenvects() == ([(2, 2, [Matrix([[1, 1]])])]) M = Matrix([[1, 2, 3], [4, 5, 6], [7, 8, 9]]) a = R(15, 2) b = 333R(1, 2) c = R(13, 2) d = (R(33, 8) + 3b/8) e = (R(33, 8) - 3b/8) def NS(e, n): return str(N(e, n)) r = [ (a - b/2, 1, [Matrix([(12 + 24/(c - b/2))/((c - b/2)e) + 3/(c - b/2), (6 + 12/(c - b/2))/e, 1])]), ( 0, 1, [Matrix([1, -2, 1])]), (a + b/2, 1, [Matrix([(12 + 24/(c + b/2))/((c + b/2)d) + 3/(c + b/2), (6 + 12/(c + b/2))/d, 1])]), ] r1 = [(NS(r[i][0], 2), NS(r[i][1], 2), [NS(j, 2) for j in r[i][2][0]]) for i in range(len(r))] r = M.eigenvects() r2 = [(NS(r[i][0], 2), NS(r[i][1], 2), [NS(j, 2) for j in r[i][2][0]]) for i in range(len(r))] assert sorted(r1) == sorted(r2) eps = Symbol('eps', real=True) M = Matrix([[abs(eps), Ieps ], [-Ieps, abs(eps) ]]) assert M.eigenvects() == ( [ ( 0, 1, [Matrix([[-Ieps/abs(eps)], [1]])]), ( 2abs(eps), 1, [ Matrix([[Ieps/abs(eps)], [1]]) ] ), ]) assert M.left_eigenvects() == ( [ (0, 1, [Matrix([[Ieps/Abs(eps), 1]])]), (2Abs(eps), 1, [Matrix([[-Ieps/Abs(eps), 1]])]) ]) M = Matrix(3, 3, [1, 2, 0, 0, 3, 0, 2, -4, 2]) M._eigenvects = M.eigenvects(simplify=False) assert max(i.q for i in M._eigenvects[0][2][0]) > 1 M._eigenvects = M.eigenvects(simplify=True) assert max(i.q for i in M._eigenvects[0][2][0]) == 1 M = Matrix([[S(1)/4, 1], [1, 1]]) assert M.eigenvects(simplify=True) == [ (S(5)/8 + sqrt(73)/8, 1, [Matrix([[-S(3)/8 + sqrt(73)/8], [1]])]), (-sqrt(73)/8 + S(5)/8, 1, [Matrix([[-sqrt(73)/8 - S(3)/8], [1]])])] assert M.eigenvects(simplify=False) ==[(S(5)/8 + sqrt(73)/8, 1, [Matrix([ [-1/(-sqrt(73)/8 - S(3)/8)], [ 1]])]), (-sqrt(73)/8 + S(5)/8, 1, [Matrix([ [-1/(-S(3)/8 + sqrt(73)/8)], [ 1]])])] m = Matrix([[1, .6, .6], [.6, .9, .9], [.9, .6, .6]]) evals = {-sqrt(385)/20 + S(5)/4: 1, sqrt(385)/20 + S(5)/4: 1, S.Zero: 1} assert m.eigenvals() == evals nevals = list(sorted(m.eigenvals(rational=False).keys())) sevals = list(sorted(evals.keys())) assert all(abs(nevals[i] - sevals[i]) < 1e-9 for i in range(len(nevals))) # issue 10719 assert Matrix([]).eigenvals() == {} assert Matrix([]).eigenvects() == [] # issue 15119 raises(NonSquareMatrixError, lambda : Matrix([[1, 2], [0, 4], [0, 0]]).eigenvals()) raises(NonSquareMatrixError, lambda : Matrix([[1, 0], [3, 4], [5, 6]]).eigenvals()) raises(NonSquareMatrixError, lambda : Matrix([[1, 2, 3], [0, 5, 6]]).eigenvals()) raises(NonSquareMatrixError, lambda : Matrix([[1, 0, 0], [4, 5, 0]]).eigenvals()) raises(NonSquareMatrixError, lambda : Matrix([[1, 2, 3], [0, 5, 6]]).eigenvals(error_when_incomplete = False)) raises(NonSquareMatrixError, lambda : Matrix([[1, 0, 0], [4, 5, 0]]).eigenvals(error_when_incomplete = False)) # issue 15125 from sympy.core.function import count_ops q = Symbol("q", positive = True) m = Matrix([[-2, exp(-q), 1], [exp(q), -2, 1], [1, 1, -2]]) assert count_ops(m.eigenvals(simplify=False)) > count_ops(m.eigenvals(simplify=True)) assert count_ops(m.eigenvals(simplify=lambda x: x)) > count_ops(m.eigenvals(simplify=True)) assert isinstance(m.eigenvals(simplify=True, multiple=False), dict) assert isinstance(m.eigenvals(simplify=True, multiple=True), list) assert isinstance(m.eigenvals(simplify=lambda x: x, multiple=False), dict) assert isinstance(m.eigenvals(simplify=lambda x: x, multiple=True), list) def test_subs(): assert Matrix([[1, x], [x, 4]]).subs(x, 5) == Matrix([[1, 5], [5, 4]]) assert Matrix([[x, 2], [x + y, 4]]).subs([[x, -1], [y, -2]]) == \ Matrix([[-1, 2], [-3, 4]]) assert Matrix([[x, 2], [x + y, 4]]).subs([(x, -1), (y, -2)]) == \ Matrix([[-1, 2], [-3, 4]]) assert Matrix([[x, 2], [x + y, 4]]).subs({x: -1, y: -2}) == \ Matrix([[-1, 2], [-3, 4]]) assert Matrix([xy]).subs({x: y - 1, y: x - 1}, simultaneous=True) == \ Matrix([(x - 1)(y - 1)]) for cls in classes: assert Matrix([[2, 0], [0, 2]]) == cls.eye(2).subs(1, 2) def test_xreplace(): assert Matrix([[1, x], [x, 4]]).xreplace({x: 5}) == \ Matrix([[1, 5], [5, 4]]) assert Matrix([[x, 2], [x + y, 4]]).xreplace({x: -1, y: -2}) == \ Matrix([[-1, 2], [-3, 4]]) for cls in classes: assert Matrix([[2, 0], [0, 2]]) == cls.eye(2).xreplace({1: 2}) def test_simplify(): n = Symbol('n') f = Function('f') M = Matrix([[ 1/x + 1/y, (x + xy) / x ], [ (f(x) + yf(x))/f(x), 2 (1/n - cos(n * pi)/n) / pi ]]) M.simplify() assert M == Matrix([[ (x + y)/(x * y), 1 + y ], [ 1 + y, 2((1 - 1cos(pin))/(pin)) ]]) eq = (1 + x)2 M = Matrix([[eq]]) M.simplify() assert M == Matrix([[eq]]) M.simplify(ratio=oo) == M assert M == Matrix([[eq.simplify(ratio=oo)]]) def test_transpose(): M = Matrix([[1, 2, 3, 4, 5, 6, 7, 8, 9, 0], [1, 2, 3, 4, 5, 6, 7, 8, 9, 0]]) assert M.T == Matrix( [ [1, 1], [2, 2], [3, 3], [4, 4], [5, 5], [6, 6], [7, 7], [8, 8], [9, 9], [0, 0] ]) assert M.T.T == M assert M.T == M.transpose() def test_conjugate(): M = Matrix([[0, I, 5], [1, 2, 0]]) assert M.T == Matrix([[0, 1], [I, 2], [5, 0]]) assert M.C == Matrix([[0, -I, 5], [1, 2, 0]]) assert M.C == M.conjugate() assert M.H == M.T.C assert M.H == Matrix([[ 0, 1], [-I, 2], [ 5, 0]]) def test_conj_dirac(): raises(AttributeError, lambda: eye(3).D) M = Matrix([[1, I, I, I], [0, 1, I, I], [0, 0, 1, I], [0, 0, 0, 1]]) assert M.D == Matrix([[ 1, 0, 0, 0], [-I, 1, 0, 0], [-I, -I, -1, 0], [-I, -I, I, -1]]) def test_trace(): M = Matrix([[1, 0, 0], [0, 5, 0], [0, 0, 8]]) assert M.trace() == 14 def test_shape(): M = Matrix([[x, 0, 0], [0, y, 0]]) assert M.shape == (2, 3) def test_col_row_op(): M = Matrix([[x, 0, 0], [0, y, 0]]) M.row_op(1, lambda r, j: r + j + 1) assert M == Matrix([[x, 0, 0], [1, y + 2, 3]]) M.col_op(0, lambda c, j: c + yj) assert M == Matrix([[x + 1, 0, 0], [1 + y, y + 2, 3]]) # neither row nor slice give copies that allow the original matrix to # be changed assert M.row(0) == Matrix([[x + 1, 0, 0]]) r1 = M.row(0) r1[0] = 42 assert M[0, 0] == x + 1 r1 = M[0, :-1] # also testing negative slice r1[0] = 42 assert M[0, 0] == x + 1 c1 = M.col(0) assert c1 == Matrix([x + 1, 1 + y]) c1[0] = 0 assert M[0, 0] == x + 1 c1 = M[:, 0] c1[0] = 42 assert M[0, 0] == x + 1 def test_zip_row_op(): for cls in classes[:2]: # XXX: immutable matrices don't support row ops M = cls.eye(3) M.zip_row_op(1, 0, lambda v, u: v + 2u) assert M == cls([[1, 0, 0], [2, 1, 0], [0, 0, 1]]) M = cls.eye(3)2 M[0, 1] = -1 M.zip_row_op(1, 0, lambda v, u: v + 2u); M assert M == cls([[2, -1, 0], [4, 0, 0], [0, 0, 2]]) def test_issue_3950(): m = Matrix([1, 2, 3]) a = Matrix([1, 2, 3]) b = Matrix([2, 2, 3]) assert not (m in []) assert not (m in [1]) assert m != 1 assert m == a assert m != b def test_issue_3981(): class Index1(object): def __index__(self): return 1 class Index2(object): def __index__(self): return 2 index1 = Index1() index2 = Index2() m = Matrix([1, 2, 3]) assert m[index2] == 3 m[index2] = 5 assert m[2] == 5 m = Matrix([[1, 2, 3], [4, 5, 6]]) assert m[index1, index2] == 6 assert m[1, index2] == 6 assert m[index1, 2] == 6 m[index1, index2] = 4 assert m[1, 2] == 4 m[1, index2] = 6 assert m[1, 2] == 6 m[index1, 2] = 8 assert m[1, 2] == 8 def test_evalf(): a = Matrix([sqrt(5), 6]) assert all(a.evalf()[i] == a[i].evalf() for i in range(2)) assert all(a.evalf(2)[i] == a[i].evalf(2) for i in range(2)) assert all(a.n(2)[i] == a[i].n(2) for i in range(2)) def test_is_symbolic(): a = Matrix([[x, x], [x, x]]) assert a.is_symbolic() is True a = Matrix([[1, 2, 3, 4], [5, 6, 7, 8]]) assert a.is_symbolic() is False a = Matrix([[1, 2, 3, 4], [5, 6, x, 8]]) assert a.is_symbolic() is True a = Matrix([[1, x, 3]]) assert a.is_symbolic() is True a = Matrix([[1, 2, 3]]) assert a.is_symbolic() is False a = Matrix([[1], [x], [3]]) assert a.is_symbolic() is True a = Matrix([[1], [2], [3]]) assert a.is_symbolic() is False def test_is_upper(): a = Matrix([[1, 2, 3]]) assert a.is_upper is True a = Matrix([[1], [2], [3]]) assert a.is_upper is False a = zeros(4, 2) assert a.is_upper is True def test_is_lower(): a = Matrix([[1, 2, 3]]) assert a.is_lower is False a = Matrix([[1], [2], [3]]) assert a.is_lower is True def test_is_nilpotent(): a = Matrix(4, 4, [0, 2, 1, 6, 0, 0, 1, 2, 0, 0, 0, 3, 0, 0, 0, 0]) assert a.is_nilpotent() a = Matrix([[1, 0], [0, 1]]) assert not a.is_nilpotent() a = Matrix([]) assert a.is_nilpotent() def test_zeros_ones_fill(): n, m = 3, 5 a = zeros(n, m) a.fill( 5 ) b = 5 ones(n, m) assert a == b assert a.rows == b.rows == 3 assert a.cols == b.cols == 5 assert a.shape == b.shape == (3, 5) assert zeros(2) == zeros(2, 2) assert ones(2) == ones(2, 2) assert zeros(2, 3) == Matrix(2, 3, [0]6) assert ones(2, 3) == Matrix(2, 3, [1]6) def test_empty_zeros(): a = zeros(0) assert a == Matrix() a = zeros(0, 2) assert a.rows == 0 assert a.cols == 2 a = zeros(2, 0) assert a.rows == 2 assert a.cols == 0 def test_issue_3749(): a = Matrix([[x*2, xy], [xsin(y), xcos(y)]]) assert a.diff(x) == Matrix([[2x, y], [sin(y), cos(y)]]) assert Matrix([ [x, -x, x2], [exp(x), 1/x - exp(-x), x + 1/x]]).limit(x, oo) == \ Matrix([[oo, -oo, oo], [oo, 0, oo]]) assert Matrix([ [(exp(x) - 1)/x, 2x + yx, xx ], [1/x, abs(x), abs(sin(x + 1))]]).limit(x, 0) == \ Matrix([[1, 0, 1], [oo, 0, sin(1)]]) assert a.integrate(x) == Matrix([ [Rational(1, 3)x*3, yx2/2], [x2sin(y)/2, x2cos(y)/2]]) def test_inv_iszerofunc(): A = eye(4) A.col_swap(0, 1) for method in "GE", "LU": assert A.inv(method=method, iszerofunc=lambda x: x == 0) == \ A.inv(method="ADJ") def test_jacobian_metrics(): rho, phi = symbols("rho,phi") X = Matrix([rhocos(phi), rhosin(phi)]) Y = Matrix([rho, phi]) J = X.jacobian(Y) assert J == X.jacobian(Y.T) assert J == (X.T).jacobian(Y) assert J == (X.T).jacobian(Y.T) g = J.Teye(J.shape[0])J g = g.applyfunc(trigsimp) assert g == Matrix([[1, 0], [0, rho*2]]) def test_jacobian2(): rho, phi = symbols("rho,phi") X = Matrix([rhocos(phi), rhosin(phi), rho2]) Y = Matrix([rho, phi]) J = Matrix([ [cos(phi), -rhosin(phi)], [sin(phi), rhocos(phi)], [ 2rho, 0], ]) assert X.jacobian(Y) == J def test_issue_4564(): X = Matrix([exp(x + y + z), exp(x + y + z), exp(x + y + z)]) Y = Matrix([x, y, z]) for i in range(1, 3): for j in range(1, 3): X_slice = X[:i, :] Y_slice = Y[:j, :] J = X_slice.jacobian(Y_slice) assert J.rows == i assert J.cols == j for k in range(j): assert J[:, k] == X_slice def test_nonvectorJacobian(): X = Matrix([[exp(x + y + z), exp(x + y + z)], [exp(x + y + z), exp(x + y + z)]]) raises(TypeError, lambda: X.jacobian(Matrix([x, y, z]))) X = X[0, :] Y = Matrix([[x, y], [x, z]]) raises(TypeError, lambda: X.jacobian(Y)) raises(TypeError, lambda: X.jacobian(Matrix([ [x, y], [x, z] ]))) def test_vec(): m = Matrix([[1, 3], [2, 4]]) m_vec = m.vec() assert m_vec.cols == 1 for i in range(4): assert m_vec[i] == i + 1 def test_vech(): m = Matrix([[1, 2], [2, 3]]) m_vech = m.vech() assert m_vech.cols == 1 for i in range(3): assert m_vech[i] == i + 1 m_vech = m.vech(diagonal=False) assert m_vech[0] == 2 m = Matrix([[1, x(x + y)], [yx + x*2, 1]]) m_vech = m.vech(diagonal=False) assert m_vech[0] == x(x + y) m = Matrix([[1, x(x + y)], [yx, 1]]) m_vech = m.vech(diagonal=False, check_symmetry=False) assert m_vech[0] == yx def test_vech_errors(): m = Matrix([[1, 3]]) raises(ShapeError, lambda: m.vech()) m = Matrix([[1, 3], [2, 4]]) raises(ValueError, lambda: m.vech()) raises(ShapeError, lambda: Matrix([ [1, 3] ]).vech()) raises(ValueError, lambda: Matrix([ [1, 3], [2, 4] ]).vech()) def test_diag(): a = Matrix([[1, 2], [2, 3]]) b = Matrix([[3, x], [y, 3]]) c = Matrix([[3, x, 3], [y, 3, z], [x, y, z]]) assert diag(a, b, b) == Matrix([ [1, 2, 0, 0, 0, 0], [2, 3, 0, 0, 0, 0], [0, 0, 3, x, 0, 0], [0, 0, y, 3, 0, 0], [0, 0, 0, 0, 3, x], [0, 0, 0, 0, y, 3], ]) assert diag(a, b, c) == Matrix([ [1, 2, 0, 0, 0, 0, 0], [2, 3, 0, 0, 0, 0, 0], [0, 0, 3, x, 0, 0, 0], [0, 0, y, 3, 0, 0, 0], [0, 0, 0, 0, 3, x, 3], [0, 0, 0, 0, y, 3, z], [0, 0, 0, 0, x, y, z], ]) assert diag(a, c, b) == Matrix([ [1, 2, 0, 0, 0, 0, 0], [2, 3, 0, 0, 0, 0, 0], [0, 0, 3, x, 3, 0, 0], [0, 0, y, 3, z, 0, 0], [0, 0, x, y, z, 0, 0], [0, 0, 0, 0, 0, 3, x], [0, 0, 0, 0, 0, y, 3], ]) a = Matrix([x, y, z]) b = Matrix([[1, 2], [3, 4]]) c = Matrix([[5, 6]]) assert diag(a, 7, b, c) == Matrix([ [x, 0, 0, 0, 0, 0], [y, 0, 0, 0, 0, 0], [z, 0, 0, 0, 0, 0], [0, 7, 0, 0, 0, 0], [0, 0, 1, 2, 0, 0], [0, 0, 3, 4, 0, 0], [0, 0, 0, 0, 5, 6], ]) assert diag(1, [2, 3], [[4, 5]]) == Matrix([ [1, 0, 0, 0], [0, 2, 0, 0], [0, 3, 0, 0], [0, 0, 4, 5]]) def test_get_diag_blocks1(): a = Matrix([[1, 2], [2, 3]]) b = Matrix([[3, x], [y, 3]]) c = Matrix([[3, x, 3], [y, 3, z], [x, y, z]]) assert a.get_diag_blocks() == [a] assert b.get_diag_blocks() == [b] assert c.get_diag_blocks() == [c] def test_get_diag_blocks2(): a = Matrix([[1, 2], [2, 3]]) b = Matrix([[3, x], [y, 3]]) c = Matrix([[3, x, 3], [y, 3, z], [x, y, z]]) assert diag(a, b, b).get_diag_blocks() == [a, b, b] assert diag(a, b, c).get_diag_blocks() == [a, b, c] assert diag(a, c, b).get_diag_blocks() == [a, c, b] assert diag(c, c, b).get_diag_blocks() == [c, c, b] def test_inv_block(): a = Matrix([[1, 2], [2, 3]]) b = Matrix([[3, x], [y, 3]]) c = Matrix([[3, x, 3], [y, 3, z], [x, y, z]]) A = diag(a, b, b) assert A.inv(try_block_diag=True) == diag(a.inv(), b.inv(), b.inv()) A = diag(a, b, c) assert A.inv(try_block_diag=True) == diag(a.inv(), b.inv(), c.inv()) A = diag(a, c, b) assert A.inv(try_block_diag=True) == diag(a.inv(), c.inv(), b.inv()) A = diag(a, a, b, a, c, a) assert A.inv(try_block_diag=True) == diag( a.inv(), a.inv(), b.inv(), a.inv(), c.inv(), a.inv()) assert A.inv(try_block_diag=True, method="ADJ") == diag( a.inv(method="ADJ"), a.inv(method="ADJ"), b.inv(method="ADJ"), a.inv(method="ADJ"), c.inv(method="ADJ"), a.inv(method="ADJ")) def test_creation_args(): """ Check that matrix dimensions can be specified using any reasonable type (see issue 4614). """ raises(ValueError, lambda: zeros(3, -1)) raises(TypeError, lambda: zeros(1, 2, 3, 4)) assert zeros(long(3)) == zeros(3) assert zeros(Integer(3)) == zeros(3) assert zeros(3.) == zeros(3) assert eye(long(3)) == eye(3) assert eye(Integer(3)) == eye(3) assert eye(3.) == eye(3) assert ones(long(3), Integer(4)) == ones(3, 4) raises(TypeError, lambda: Matrix(5)) raises(TypeError, lambda: Matrix(1, 2)) def test_diagonal_symmetrical(): m = Matrix(2, 2, [0, 1, 1, 0]) assert not m.is_diagonal() assert m.is_symmetric() assert m.is_symmetric(simplify=False) m = Matrix(2, 2, [1, 0, 0, 1]) assert m.is_diagonal() m = diag(1, 2, 3) assert m.is_diagonal() assert m.is_symmetric() m = Matrix(3, 3, [1, 0, 0, 0, 2, 0, 0, 0, 3]) assert m == diag(1, 2, 3) m = Matrix(2, 3, zeros(2, 3)) assert not m.is_symmetric() assert m.is_diagonal() m = Matrix(((5, 0), (0, 6), (0, 0))) assert m.is_diagonal() m = Matrix(((5, 0, 0), (0, 6, 0))) assert m.is_diagonal() m = Matrix(3, 3, [1, x2 + 2x + 1, y, (x + 1)*2, 2, 0, y, 0, 3]) assert m.is_symmetric() assert not m.is_symmetric(simplify=False) assert m.expand().is_symmetric(simplify=False) def test_diagonalization(): m = Matrix(3, 2, [-3, 1, -3, 20, 3, 10]) assert not m.is_diagonalizable() assert not m.is_symmetric() raises(NonSquareMatrixError, lambda: m.diagonalize()) # diagonalizable m = diag(1, 2, 3) (P, D) = m.diagonalize() assert P == eye(3) assert D == m m = Matrix(2, 2, [0, 1, 1, 0]) assert m.is_symmetric() assert m.is_diagonalizable() (P, D) = m.diagonalize() assert P.inv() m * P == D m = Matrix(2, 2, [1, 0, 0, 3]) assert m.is_symmetric() assert m.is_diagonalizable() (P, D) = m.diagonalize() assert P.inv() * m * P == D assert P == eye(2) assert D == m m = Matrix(2, 2, [1, 1, 0, 0]) assert m.is_diagonalizable() (P, D) = m.diagonalize() assert P.inv() * m * P == D m = Matrix(3, 3, [1, 2, 0, 0, 3, 0, 2, -4, 2]) assert m.is_diagonalizable() (P, D) = m.diagonalize() assert P.inv() * m * P == D for i in P: assert i.as_numer_denom()[1] == 1 m = Matrix(2, 2, [1, 0, 0, 0]) assert m.is_diagonal() assert m.is_diagonalizable() (P, D) = m.diagonalize() assert P.inv() * m * P == D assert P == Matrix([[0, 1], [1, 0]]) # diagonalizable, complex only m = Matrix(2, 2, [0, 1, -1, 0]) assert not m.is_diagonalizable(True) raises(MatrixError, lambda: m.diagonalize(True)) assert m.is_diagonalizable() (P, D) = m.diagonalize() assert P.inv() * m * P == D # not diagonalizable m = Matrix(2, 2, [0, 1, 0, 0]) assert not m.is_diagonalizable() raises(MatrixError, lambda: m.diagonalize()) m = Matrix(3, 3, [-3, 1, -3, 20, 3, 10, 2, -2, 4]) assert not m.is_diagonalizable() raises(MatrixError, lambda: m.diagonalize()) # symbolic a, b, c, d = symbols('a b c d') m = Matrix(2, 2, [a, c, c, b]) assert m.is_symmetric() assert m.is_diagonalizable() @XFAIL def test_eigen_vects(): m = Matrix(2, 2, [1, 0, 0, I]) raises(NotImplementedError, lambda: m.is_diagonalizable(True)) # !!! bug because of eigenvects() or roots(x*2 + (-1 - I)x + I, x) # see issue 5292 assert not m.is_diagonalizable(True) raises(MatrixError, lambda: m.diagonalize(True)) (P, D) = m.diagonalize(True) def test_jordan_form(): m = Matrix(3, 2, [-3, 1, -3, 20, 3, 10]) raises(NonSquareMatrixError, lambda: m.jordan_form()) # diagonalizable m = Matrix(3, 3, [7, -12, 6, 10, -19, 10, 12, -24, 13]) Jmust = Matrix(3, 3, [-1, 0, 0, 0, 1, 0, 0, 0, 1]) P, J = m.jordan_form() assert Jmust == J assert Jmust == m.diagonalize()[1] # m = Matrix(3, 3, [0, 6, 3, 1, 3, 1, -2, 2, 1]) # m.jordan_form() # very long # m.jordan_form() # # diagonalizable, complex only # Jordan cells # complexity: one of eigenvalues is zero m = Matrix(3, 3, [0, 1, 0, -4, 4, 0, -2, 1, 2]) # The blocks are ordered according to the value of their eigenvalues, # in order to make the matrix compatible with .diagonalize() Jmust = Matrix(3, 3, [2, 1, 0, 0, 2, 0, 0, 0, 2]) P, J = m.jordan_form() assert Jmust == J # complexity: all of eigenvalues are equal m = Matrix(3, 3, [2, 6, -15, 1, 1, -5, 1, 2, -6]) # Jmust = Matrix(3, 3, [-1, 0, 0, 0, -1, 1, 0, 0, -1]) # same here see 1456ff Jmust = Matrix(3, 3, [-1, 1, 0, 0, -1, 0, 0, 0, -1]) P, J = m.jordan_form() assert Jmust == J # complexity: two of eigenvalues are zero m = Matrix(3, 3, [4, -5, 2, 5, -7, 3, 6, -9, 4]) Jmust = Matrix(3, 3, [0, 1, 0, 0, 0, 0, 0, 0, 1]) P, J = m.jordan_form() assert Jmust == J m = Matrix(4, 4, [6, 5, -2, -3, -3, -1, 3, 3, 2, 1, -2, -3, -1, 1, 5, 5]) Jmust = Matrix(4, 4, [2, 1, 0, 0, 0, 2, 0, 0, 0, 0, 2, 1, 0, 0, 0, 2] ) P, J = m.jordan_form() assert Jmust == J m = Matrix(4, 4, [6, 2, -8, -6, -3, 2, 9, 6, 2, -2, -8, -6, -1, 0, 3, 4]) # Jmust = Matrix(4, 4, [2, 0, 0, 0, 0, 2, 1, 0, 0, 0, 2, 0, 0, 0, 0, -2]) # same here see 1456ff Jmust = Matrix(4, 4, [-2, 0, 0, 0, 0, 2, 1, 0, 0, 0, 2, 0, 0, 0, 0, 2]) P, J = m.jordan_form() assert Jmust == J m = Matrix(4, 4, [5, 4, 2, 1, 0, 1, -1, -1, -1, -1, 3, 0, 1, 1, -1, 2]) assert not m.is_diagonalizable() Jmust = Matrix(4, 4, [1, 0, 0, 0, 0, 2, 0, 0, 0, 0, 4, 1, 0, 0, 0, 4]) P, J = m.jordan_form() assert Jmust == J # checking for maximum precision to remain unchanged m = Matrix([[Float('1.0', precision=110), Float('2.0', precision=110)], [Float('3.14159265358979323846264338327', precision=110), Float('4.0', precision=110)]]) P, J = m.jordan_form() for term in J._mat: if isinstance(term, Float): assert term._prec == 110 def test_jordan_form_complex_issue_9274(): A = Matrix([[ 2, 4, 1, 0], [-4, 2, 0, 1], [ 0, 0, 2, 4], [ 0, 0, -4, 2]]) p = 2 - 4I; q = 2 + 4I; Jmust1 = Matrix([[p, 1, 0, 0], [0, p, 0, 0], [0, 0, q, 1], [0, 0, 0, q]]) Jmust2 = Matrix([[q, 1, 0, 0], [0, q, 0, 0], [0, 0, p, 1], [0, 0, 0, p]]) P, J = A.jordan_form() assert J == Jmust1 or J == Jmust2 assert simplify(PJP.inv()) == A def test_issue_10220(): # two non-orthogonal Jordan blocks with eigenvalue 1 M = Matrix([[1, 0, 0, 1], [0, 1, 1, 0], [0, 0, 1, 1], [0, 0, 0, 1]]) P, J = M.jordan_form() assert P == Matrix([[0, 1, 0, 1], [1, 0, 0, 0], [0, 1, 0, 0], [0, 0, 1, 0]]) assert J == Matrix([ [1, 1, 0, 0], [0, 1, 1, 0], [0, 0, 1, 0], [0, 0, 0, 1]]) def test_Matrix_berkowitz_charpoly(): UA, K_i, K_w = symbols('UA K_i K_w') A = Matrix([[-K_i - UA + K_i*2/(K_i + K_w), K_iK_w/(K_i + K_w)], [ K_iK_w/(K_i + K_w), -K_w + K_w2/(K_i + K_w)]]) charpoly = A.charpoly(x) assert charpoly == \ Poly(x2 + (K_iUA + K_wUA + 2K_iK_w)/(K_i + K_w)x + K_iK_wUA/(K_i + K_w), x, domain='ZZ(K_i,K_w,UA)') assert type(charpoly) is PurePoly A = Matrix([[1, 3], [2, 0]]) assert A.charpoly() == A.charpoly(x) == PurePoly(x2 - x - 6) A = Matrix([[1, 2], [x, 0]]) p = A.charpoly(x) assert p.gen != x assert p.as_expr().subs(p.gen, x) == x2 - 3x def test_exp(): m = Matrix([[3, 4], [0, -2]]) m_exp = Matrix([[exp(3), -4exp(-2)/5 + 4exp(3)/5], [0, exp(-2)]]) assert m.exp() == m_exp assert exp(m) == m_exp m = Matrix([[1, 0], [0, 1]]) assert m.exp() == Matrix([[E, 0], [0, E]]) assert exp(m) == Matrix([[E, 0], [0, E]]) m = Matrix([[1, -1], [1, 1]]) assert m.exp() == Matrix([[Ecos(1), -Esin(1)], [Esin(1), Ecos(1)]]) def test_has(): A = Matrix(((x, y), (2, 3))) assert A.has(x) assert not A.has(z) assert A.has(Symbol) A = A.subs(x, 2) assert not A.has(x) def test_LUdecomposition_Simple_iszerofunc(): # Test if callable passed to matrices.LUdecomposition_Simple() as iszerofunc keyword argument is used inside # matrices.LUdecomposition_Simple() magic_string = "I got passed in!" def goofyiszero(value): raise ValueError(magic_string) try: lu, p = Matrix([[1, 0], [0, 1]]).LUdecomposition_Simple(iszerofunc=goofyiszero) except ValueError as err: assert magic_string == err.args[0] return assert False def test_LUdecomposition_iszerofunc(): # Test if callable passed to matrices.LUdecomposition() as iszerofunc keyword argument is used inside # matrices.LUdecomposition_Simple() magic_string = "I got passed in!" def goofyiszero(value): raise ValueError(magic_string) try: l, u, p = Matrix([[1, 0], [0, 1]]).LUdecomposition(iszerofunc=goofyiszero) except ValueError as err: assert magic_string == err.args[0] return assert False def test_find_reasonable_pivot_naive_finds_guaranteed_nonzero1(): # Test if matrices._find_reasonable_pivot_naive() # finds a guaranteed non-zero pivot when the # some of the candidate pivots are symbolic expressions. # Keyword argument: simpfunc=None indicates that no simplifications # should be performed during the search. x = Symbol('x') column = Matrix(3, 1, [x, cos(x)2 + sin(x)2, Rational(1, 2)]) pivot_offset, pivot_val, pivot_assumed_nonzero, simplified =\ _find_reasonable_pivot_naive(column) assert pivot_val == Rational(1, 2) def test_find_reasonable_pivot_naive_finds_guaranteed_nonzero2(): # Test if matrices._find_reasonable_pivot_naive() # finds a guaranteed non-zero pivot when the # some of the candidate pivots are symbolic expressions. # Keyword argument: simpfunc=_simplify indicates that the search # should attempt to simplify candidate pivots. x = Symbol('x') column = Matrix(3, 1, [x, cos(x)2+sin(x)2+x2, cos(x)2+sin(x)2]) pivot_offset, pivot_val, pivot_assumed_nonzero, simplified =\ _find_reasonable_pivot_naive(column, simpfunc=_simplify) assert pivot_val == 1 def test_find_reasonable_pivot_naive_simplifies(): # Test if matrices._find_reasonable_pivot_naive() # simplifies candidate pivots, and reports # their offsets correctly. x = Symbol('x') column = Matrix(3, 1, [x, cos(x)2+sin(x)2+x, cos(x)2+sin(x)2]) pivot_offset, pivot_val, pivot_assumed_nonzero, simplified =\ _find_reasonable_pivot_naive(column, simpfunc=_simplify) assert len(simplified) == 2 assert simplified[0][0] == 1 assert simplified[0][1] == 1+x assert simplified[1][0] == 2 assert simplified[1][1] == 1 def test_errors(): raises(ValueError, lambda: Matrix([[1, 2], [1]])) raises(IndexError, lambda: Matrix([[1, 2]])[1.2, 5]) raises(IndexError, lambda: Matrix([[1, 2]])[1, 5.2]) raises(ValueError, lambda: randMatrix(3, c=4, symmetric=True)) raises(ValueError, lambda: Matrix([1, 2]).reshape(4, 6)) raises(ShapeError, lambda: Matrix([[1, 2], [3, 4]]).copyin_matrix([1, 0], Matrix([1, 2]))) raises(TypeError, lambda: Matrix([[1, 2], [3, 4]]).copyin_list([0, 1], set([]))) raises(NonSquareMatrixError, lambda: Matrix([[1, 2, 3], [2, 3, 0]]).inv()) raises(ShapeError, lambda: Matrix(1, 2, [1, 2]).row_join(Matrix([[1, 2], [3, 4]]))) raises( ShapeError, lambda: Matrix([1, 2]).col_join(Matrix([[1, 2], [3, 4]]))) raises(ShapeError, lambda: Matrix([1]).row_insert(1, Matrix([[1, 2], [3, 4]]))) raises(ShapeError, lambda: Matrix([1]).col_insert(1, Matrix([[1, 2], [3, 4]]))) raises(NonSquareMatrixError, lambda: Matrix([1, 2]).trace()) raises(TypeError, lambda: Matrix([1]).applyfunc(1)) raises(ShapeError, lambda: Matrix([1]).LUsolve(Matrix([[1, 2], [3, 4]]))) raises(ValueError, lambda: Matrix([[1, 2], [3, 4]]).minor(4, 5)) raises(ValueError, lambda: Matrix([[1, 2], [3, 4]]).minor_submatrix(4, 5)) raises(TypeError, lambda: Matrix([1, 2, 3]).cross(1)) raises(TypeError, lambda: Matrix([1, 2, 3]).dot(1)) raises(ShapeError, lambda: Matrix([1, 2, 3]).dot(Matrix([1, 2]))) raises(ShapeError, lambda: Matrix([1, 2]).dot([])) raises(TypeError, lambda: Matrix([1, 2]).dot('a')) with warns_deprecated_sympy(): Matrix([[1, 2], [3, 4]]).dot(Matrix([[4, 3], [1, 2]])) raises(ShapeError, lambda: Matrix([1, 2]).dot([1, 2, 3])) raises(NonSquareMatrixError, lambda: Matrix([1, 2, 3]).exp()) raises(ShapeError, lambda: Matrix([[1, 2], [3, 4]]).normalized()) raises(ValueError, lambda: Matrix([1, 2]).inv(method='not a method')) raises(NonSquareMatrixError, lambda: Matrix([1, 2]).inverse_GE()) raises(ValueError, lambda: Matrix([[1, 2], [1, 2]]).inverse_GE()) raises(NonSquareMatrixError, lambda: Matrix([1, 2]).inverse_ADJ()) raises(ValueError, lambda: Matrix([[1, 2], [1, 2]]).inverse_ADJ()) raises(NonSquareMatrixError, lambda: Matrix([1, 2]).inverse_LU()) raises(NonSquareMatrixError, lambda: Matrix([1, 2]).is_nilpotent()) raises(NonSquareMatrixError, lambda: Matrix([1, 2]).det()) raises(ValueError, lambda: Matrix([[1, 2], [3, 4]]).det(method='Not a real method')) raises(ValueError, lambda: Matrix([[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12], [13, 14, 15, 16]]).det(iszerofunc="Not function")) raises(ValueError, lambda: Matrix([[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12], [13, 14, 15, 16]]).det(iszerofunc=False)) raises(ValueError, lambda: hessian(Matrix([[1, 2], [3, 4]]), Matrix([[1, 2], [2, 1]]))) raises(ValueError, lambda: hessian(Matrix([[1, 2], [3, 4]]), [])) raises(ValueError, lambda: hessian(Symbol('x')2, 'a')) raises(IndexError, lambda: eye(3)[5, 2]) raises(IndexError, lambda: eye(3)[2, 5]) M = Matrix(((1, 2, 3, 4), (5, 6, 7, 8), (9, 10, 11, 12), (13, 14, 15, 16))) raises(ValueError, lambda: M.det('method=LU_decomposition()')) V = Matrix([[10, 10, 10]]) M = Matrix([[1, 2, 3], [2, 3, 4], [3, 4, 5]]) raises(ValueError, lambda: M.row_insert(4.7, V)) M = Matrix([[1, 2, 3], [2, 3, 4], [3, 4, 5]]) raises(ValueError, lambda: M.col_insert(-4.2, V)) def test_len(): assert len(Matrix()) == 0 assert len(Matrix([[1, 2]])) == len(Matrix([[1], [2]])) == 2 assert len(Matrix(0, 2, lambda i, j: 0)) == \ len(Matrix(2, 0, lambda i, j: 0)) == 0 assert len(Matrix([[0, 1, 2], [3, 4, 5]])) == 6 assert Matrix([1]) == Matrix([[1]]) assert not Matrix() assert Matrix() == Matrix([]) def test_integrate(): A = Matrix(((1, 4, x), (y, 2, 4), (10, 5, x2))) assert A.integrate(x) == \ Matrix(((x, 4x, x*2/2), (xy, 2x, 4x), (10x, 5x, x*3/3))) assert A.integrate(y) == \ Matrix(((y, 4y, xy), (y2/2, 2y, 4y), (10y, 5y, yx2))) def test_limit(): A = Matrix(((1, 4, sin(x)/x), (y, 2, 4), (10, 5, x2 + 1))) assert A.limit(x, 0) == Matrix(((1, 4, 1), (y, 2, 4), (10, 5, 1))) def test_diff(): A = MutableDenseMatrix(((1, 4, x), (y, 2, 4), (10, 5, x*2 + 1))) assert isinstance(A.diff(x), type(A)) assert A.diff(x) == MutableDenseMatrix(((0, 0, 1), (0, 0, 0), (0, 0, 2x))) assert A.diff(y) == MutableDenseMatrix(((0, 0, 0), (1, 0, 0), (0, 0, 0))) assert diff(A, x) == MutableDenseMatrix(((0, 0, 1), (0, 0, 0), (0, 0, 2x))) assert diff(A, y) == MutableDenseMatrix(((0, 0, 0), (1, 0, 0), (0, 0, 0))) A_imm = A.as_immutable() assert isinstance(A_imm.diff(x), type(A_imm)) assert A_imm.diff(x) == ImmutableDenseMatrix(((0, 0, 1), (0, 0, 0), (0, 0, 2x))) assert A_imm.diff(y) == ImmutableDenseMatrix(((0, 0, 0), (1, 0, 0), (0, 0, 0))) assert diff(A_imm, x) == ImmutableDenseMatrix(((0, 0, 1), (0, 0, 0), (0, 0, 2x))) assert diff(A_imm, y) == ImmutableDenseMatrix(((0, 0, 0), (1, 0, 0), (0, 0, 0))) def test_diff_by_matrix(): # Derive matrix by matrix: A = MutableDenseMatrix([[x, y], [z, t]]) assert A.diff(A) == Array([[[[1, 0], [0, 0]], [[0, 1], [0, 0]]], [[[0, 0], [1, 0]], [[0, 0], [0, 1]]]]) assert diff(A, A) == Array([[[[1, 0], [0, 0]], [[0, 1], [0, 0]]], [[[0, 0], [1, 0]], [[0, 0], [0, 1]]]]) A_imm = A.as_immutable() assert A_imm.diff(A_imm) == Array([[[[1, 0], [0, 0]], [[0, 1], [0, 0]]], [[[0, 0], [1, 0]], [[0, 0], [0, 1]]]]) assert diff(A_imm, A_imm) == Array([[[[1, 0], [0, 0]], [[0, 1], [0, 0]]], [[[0, 0], [1, 0]], [[0, 0], [0, 1]]]]) # Derive a constant matrix: assert A.diff(a) == MutableDenseMatrix([[0, 0], [0, 0]]) B = ImmutableDenseMatrix([a, b]) assert A.diff(B) == A.zeros(2) # Test diff with tuples: dB = B.diff([[a, b]]) assert dB.shape == (2, 2, 1) assert dB == Array([[[1], [0]], [[0], [1]]]) f = Function("f") fxyz = f(x, y, z) assert fxyz.diff([[x, y, z]]) == Array([fxyz.diff(x), fxyz.diff(y), fxyz.diff(z)]) assert fxyz.diff(([x, y, z], 2)) == Array([ [fxyz.diff(x, 2), fxyz.diff(x, y), fxyz.diff(x, z)], [fxyz.diff(x, y), fxyz.diff(y, 2), fxyz.diff(y, z)], [fxyz.diff(x, z), fxyz.diff(z, y), fxyz.diff(z, 2)], ]) expr = sin(x)exp(y) assert expr.diff([[x, y]]) == Array([cos(x)exp(y), sin(x)exp(y)]) assert expr.diff(y, ((x, y),)) == Array([cos(x)exp(y), sin(x)exp(y)]) assert expr.diff(x, ((x, y),)) == Array([-sin(x)exp(y), cos(x)exp(y)]) assert expr.diff(((y, x),), [[x, y]]) == Array([[cos(x)exp(y), -sin(x)exp(y)], [sin(x)exp(y), cos(x)exp(y)]]) # Test different notations: fxyz.diff(x).diff(y).diff(x) == fxyz.diff(((x, y, z),), 3)[0, 1, 0] fxyz.diff(z).diff(y).diff(x) == fxyz.diff(((x, y, z),), 3)[2, 1, 0] fxyz.diff([[x, y, z]], ((z, y, x),)) == Array([[fxyz.diff(i).diff(j) for i in (x, y, z)] for j in (z, y, x)]) # Test scalar derived by matrix remains matrix: res = x.diff(Matrix([[x, y]])) assert isinstance(res, ImmutableDenseMatrix) assert res == Matrix([[1, 0]]) res = (x*3).diff(Matrix([[x, y]])) assert isinstance(res, ImmutableDenseMatrix) assert res == Matrix([[3x2, 0]]) def test_getattr(): A = Matrix(((1, 4, x), (y, 2, 4), (10, 5, x2 + 1))) raises(AttributeError, lambda: A.nonexistantattribute) assert getattr(A, 'diff')(x) == Matrix(((0, 0, 1), (0, 0, 0), (0, 0, 2x))) def test_hessenberg(): A = Matrix([[3, 4, 1], [2, 4, 5], [0, 1, 2]]) assert A.is_upper_hessenberg A = A.T assert A.is_lower_hessenberg A[0, -1] = 1 assert A.is_lower_hessenberg is False A = Matrix([[3, 4, 1], [2, 4, 5], [3, 1, 2]]) assert not A.is_upper_hessenberg A = zeros(5, 2) assert A.is_upper_hessenberg def test_cholesky(): raises(NonSquareMatrixError, lambda: Matrix((1, 2)).cholesky()) raises(ValueError, lambda: Matrix(((1, 2), (3, 4))).cholesky()) raises(ValueError, lambda: Matrix(((5 + I, 0), (0, 1))).cholesky()) raises(ValueError, lambda: Matrix(((1, 5), (5, 1))).cholesky()) raises(ValueError, lambda: Matrix(((1, 2), (3, 4))).cholesky(hermitian=False)) assert Matrix(((5 + I, 0), (0, 1))).cholesky(hermitian=False) == Matrix([ [sqrt(5 + I), 0], [0, 1]]) A = Matrix(((1, 5), (5, 1))) L = A.cholesky(hermitian=False) assert L == Matrix([[1, 0], [5, 2sqrt(6)I]]) assert LL.T == A A = Matrix(((25, 15, -5), (15, 18, 0), (-5, 0, 11))) L = A.cholesky() assert L * L.T == A assert L.is_lower assert L == Matrix([[5, 0, 0], [3, 3, 0], [-1, 1, 3]]) A = Matrix(((4, -2I, 2 + 2I), (2I, 2, -1 + I), (2 - 2I, -1 - I, 11))) assert A.cholesky() == Matrix(((2, 0, 0), (I, 1, 0), (1 - I, 0, 3))) def test_LDLdecomposition(): raises(NonSquareMatrixError, lambda: Matrix((1, 2)).LDLdecomposition()) raises(ValueError, lambda: Matrix(((1, 2), (3, 4))).LDLdecomposition()) raises(ValueError, lambda: Matrix(((5 + I, 0), (0, 1))).LDLdecomposition()) raises(ValueError, lambda: Matrix(((1, 5), (5, 1))).LDLdecomposition()) raises(ValueError, lambda: Matrix(((1, 2), (3, 4))).LDLdecomposition(hermitian=False)) A = Matrix(((1, 5), (5, 1))) L, D = A.LDLdecomposition(hermitian=False) assert L * D * L.T == A A = Matrix(((25, 15, -5), (15, 18, 0), (-5, 0, 11))) L, D = A.LDLdecomposition() assert L * D * L.T == A assert L.is_lower assert L == Matrix([[1, 0, 0], [ S(3)/5, 1, 0], [S(-1)/5, S(1)/3, 1]]) assert D.is_diagonal() assert D == Matrix([[25, 0, 0], [0, 9, 0], [0, 0, 9]]) A = Matrix(((4, -2I, 2 + 2I), (2I, 2, -1 + I), (2 - 2I, -1 - I, 11))) L, D = A.LDLdecomposition() assert expand_mul(L * D * L.H) == A assert L == Matrix(((1, 0, 0), (I/2, 1, 0), (S(1)/2 - I/2, 0, 1))) assert D == Matrix(((4, 0, 0), (0, 1, 0), (0, 0, 9))) def test_cholesky_solve(): A = Matrix([[2, 3, 5], [3, 6, 2], [8, 3, 6]]) x = Matrix(3, 1, [3, 7, 5]) b = Ax soln = A.cholesky_solve(b) assert soln == x A = Matrix([[0, -1, 2], [5, 10, 7], [8, 3, 4]]) x = Matrix(3, 1, [-1, 2, 5]) b = Ax soln = A.cholesky_solve(b) assert soln == x A = Matrix(((1, 5), (5, 1))) x = Matrix((4, -3)) b = Ax soln = A.cholesky_solve(b) assert soln == x A = Matrix(((9, 3I), (-3I, 5))) x = Matrix((-2, 1)) b = Ax soln = A.cholesky_solve(b) assert expand_mul(soln) == x A = Matrix(((9I, 3), (-3 + I, 5))) x = Matrix((2 + 3I, -1)) b = Ax soln = A.cholesky_solve(b) assert expand_mul(soln) == x a00, a01, a11, b0, b1 = symbols('a00, a01, a11, b0, b1') A = Matrix(((a00, a01), (a01, a11))) b = Matrix((b0, b1)) x = A.cholesky_solve(b) assert simplify(Ax) == b def test_LDLsolve(): A = Matrix([[2, 3, 5], [3, 6, 2], [8, 3, 6]]) x = Matrix(3, 1, [3, 7, 5]) b = Ax soln = A.LDLsolve(b) assert soln == x A = Matrix([[0, -1, 2], [5, 10, 7], [8, 3, 4]]) x = Matrix(3, 1, [-1, 2, 5]) b = Ax soln = A.LDLsolve(b) assert soln == x A = Matrix(((9, 3I), (-3I, 5))) x = Matrix((-2, 1)) b = Ax soln = A.LDLsolve(b) assert expand_mul(soln) == x A = Matrix(((9I, 3), (-3 + I, 5))) x = Matrix((2 + 3I, -1)) b = Ax soln = A.cholesky_solve(b) assert expand_mul(soln) == x def test_lower_triangular_solve(): raises(NonSquareMatrixError, lambda: Matrix([1, 0]).lower_triangular_solve(Matrix([0, 1]))) raises(ShapeError, lambda: Matrix([[1, 0], [0, 1]]).lower_triangular_solve(Matrix([1]))) raises(ValueError, lambda: Matrix([[2, 1], [1, 2]]).lower_triangular_solve( Matrix([[1, 0], [0, 1]]))) A = Matrix([[1, 0], [0, 1]]) B = Matrix([[x, y], [y, x]]) C = Matrix([[4, 8], [2, 9]]) assert A.lower_triangular_solve(B) == B assert A.lower_triangular_solve(C) == C def test_upper_triangular_solve(): raises(NonSquareMatrixError, lambda: Matrix([1, 0]).upper_triangular_solve(Matrix([0, 1]))) raises(TypeError, lambda: Matrix([[1, 0], [0, 1]]).upper_triangular_solve(Matrix([1]))) raises(TypeError, lambda: Matrix([[2, 1], [1, 2]]).upper_triangular_solve( Matrix([[1, 0], [0, 1]]))) A = Matrix([[1, 0], [0, 1]]) B = Matrix([[x, y], [y, x]]) C = Matrix([[2, 4], [3, 8]]) assert A.upper_triangular_solve(B) == B assert A.upper_triangular_solve(C) == C def test_diagonal_solve(): raises(TypeError, lambda: Matrix([1, 1]).diagonal_solve(Matrix([1]))) A = Matrix([[1, 0], [0, 1]])2 B = Matrix([[x, y], [y, x]]) assert A.diagonal_solve(B) == B/2 def test_matrix_norm(): # Vector Tests # Test columns and symbols x = Symbol('x', real=True) v = Matrix([cos(x), sin(x)]) assert trigsimp(v.norm(2)) == 1 assert v.norm(10) == Pow(cos(x)10 + sin(x)10, S(1)/10) # Test Rows A = Matrix([[5, Rational(3, 2)]]) assert A.norm() == Pow(25 + Rational(9, 4), S(1)/2) assert A.norm(oo) == max(A._mat) assert A.norm(-oo) == min(A._mat) # Matrix Tests # Intuitive test A = Matrix([[1, 1], [1, 1]]) assert A.norm(2) == 2 assert A.norm(-2) == 0 assert A.norm('frobenius') == 2 assert eye(10).norm(2) == eye(10).norm(-2) == 1 assert A.norm(oo) == 2 # Test with Symbols and more complex entries A = Matrix([[3, y, y], [x, S(1)/2, -pi]]) assert (A.norm('fro') == sqrt(S(37)/4 + 2abs(y)2 + pi2 + x*2)) # Check non-square A = Matrix([[1, 2, -3], [4, 5, Rational(13, 2)]]) assert A.norm(2) == sqrt(S(389)/8 + sqrt(78665)/8) assert A.norm(-2) == S(0) assert A.norm('frobenius') == sqrt(389)/2 # Test properties of matrix norms # https://en.wikipedia.org/wiki/Matrix_norm#Definition # Two matrices A = Matrix([[1, 2], [3, 4]]) B = Matrix([[5, 5], [-2, 2]]) C = Matrix([[0, -I], [I, 0]]) D = Matrix([[1, 0], [0, -1]]) L = [A, B, C, D] alpha = Symbol('alpha', real=True) for order in ['fro', 2, -2]: # Zero Check assert zeros(3).norm(order) == S(0) # Check Triangle Inequality for all Pairs of Matrices for X in L: for Y in L: dif = (X.norm(order) + Y.norm(order) - (X + Y).norm(order)) assert (dif >= 0) # Scalar multiplication linearity for M in [A, B, C, D]: dif = simplify((alphaM).norm(order) - abs(alpha) * M.norm(order)) assert dif == 0 # Test Properties of Vector Norms # https://en.wikipedia.org/wiki/Vector_norm # Two column vectors a = Matrix([1, 1 - 1I, -3]) b = Matrix([S(1)/2, 1I, 1]) c = Matrix([-1, -1, -1]) d = Matrix([3, 2, I]) e = Matrix([Integer(1e2), Rational(1, 1e2), 1]) L = [a, b, c, d, e] alpha = Symbol('alpha', real=True) for order in [1, 2, -1, -2, S.Infinity, S.NegativeInfinity, pi]: # Zero Check if order > 0: assert Matrix([0, 0, 0]).norm(order) == S(0) # Triangle inequality on all pairs if order >= 1: # Triangle InEq holds only for these norms for X in L: for Y in L: dif = (X.norm(order) + Y.norm(order) - (X + Y).norm(order)) assert simplify(dif >= 0) is S.true # Linear to scalar multiplication if order in [1, 2, -1, -2, S.Infinity, S.NegativeInfinity]: for X in L: dif = simplify((alphaX).norm(order) - (abs(alpha) X.norm(order))) assert dif == 0 # ord=1 M = Matrix(3, 3, [1, 3, 0, -2, -1, 0, 3, 9, 6]) assert M.norm(1) == 13 def test_condition_number(): x = Symbol('x', real=True) A = eye(3) A[0, 0] = 10 A[2, 2] = S(1)/10 assert A.condition_number() == 100 A[1, 1] = x assert A.condition_number() == Max(10, Abs(x)) / Min(S(1)/10, Abs(x)) M = Matrix([[cos(x), sin(x)], [-sin(x), cos(x)]]) Mc = M.condition_number() assert all(Float(1.).epsilon_eq(Mc.subs(x, val).evalf()) for val in [Rational(1, 5), Rational(1, 2), Rational(1, 10), pi/2, pi, 7pi/4 ]) #issue 10782 assert Matrix([]).condition_number() == 0 def test_equality(): A = Matrix(((1, 2, 3), (4, 5, 6), (7, 8, 9))) B = Matrix(((9, 8, 7), (6, 5, 4), (3, 2, 1))) assert A == A[:, :] assert not A != A[:, :] assert not A == B assert A != B assert A != 10 assert not A == 10 # A SparseMatrix can be equal to a Matrix C = SparseMatrix(((1, 0, 0), (0, 1, 0), (0, 0, 1))) D = Matrix(((1, 0, 0), (0, 1, 0), (0, 0, 1))) assert C == D assert not C != D def test_col_join(): assert eye(3).col_join(Matrix([[7, 7, 7]])) == \ Matrix([[1, 0, 0], [0, 1, 0], [0, 0, 1], [7, 7, 7]]) def test_row_insert(): r4 = Matrix([[4, 4, 4]]) for i in range(-4, 5): l = [1, 0, 0] l.insert(i, 4) assert flatten(eye(3).row_insert(i, r4).col(0).tolist()) == l def test_col_insert(): c4 = Matrix([4, 4, 4]) for i in range(-4, 5): l = [0, 0, 0] l.insert(i, 4) assert flatten(zeros(3).col_insert(i, c4).row(0).tolist()) == l def test_normalized(): assert Matrix([3, 4]).normalized() == \ Matrix([Rational(3, 5), Rational(4, 5)]) # Zero vector trivial cases assert Matrix([0, 0, 0]).normalized() == Matrix([0, 0, 0]) # Machine precision error truncation trivial cases m = Matrix([0,0,1.e-100]) assert m.normalized( iszerofunc=lambda x: x.evalf(n=10, chop=True).is_zero ) == Matrix([0, 0, 0]) def test_print_nonzero(): assert capture(lambda: eye(3).print_nonzero()) == \ '[X ]\n[ X ]\n[ X]\n' assert capture(lambda: eye(3).print_nonzero('.')) == \ '[. ]\n[ . ]\n[ .]\n' def test_zeros_eye(): assert Matrix.eye(3) == eye(3) assert Matrix.zeros(3) == zeros(3) assert ones(3, 4) == Matrix(3, 4, [1]12) i = Matrix([[1, 0], [0, 1]]) z = Matrix([[0, 0], [0, 0]]) for cls in classes: m = cls.eye(2) assert i == m # but m == i will fail if m is immutable assert i == eye(2, cls=cls) assert type(m) == cls m = cls.zeros(2) assert z == m assert z == zeros(2, cls=cls) assert type(m) == cls def test_is_zero(): assert Matrix().is_zero assert Matrix([[0, 0], [0, 0]]).is_zero assert zeros(3, 4).is_zero assert not eye(3).is_zero assert Matrix([[x, 0], [0, 0]]).is_zero == None assert SparseMatrix([[x, 0], [0, 0]]).is_zero == None assert ImmutableMatrix([[x, 0], [0, 0]]).is_zero == None assert ImmutableSparseMatrix([[x, 0], [0, 0]]).is_zero == None assert Matrix([[x, 1], [0, 0]]).is_zero == False a = Symbol('a', nonzero=True) assert Matrix([[a, 0], [0, 0]]).is_zero == False def test_rotation_matrices(): # This tests the rotation matrices by rotating about an axis and back. theta = pi/3 r3_plus = rot_axis3(theta) r3_minus = rot_axis3(-theta) r2_plus = rot_axis2(theta) r2_minus = rot_axis2(-theta) r1_plus = rot_axis1(theta) r1_minus = rot_axis1(-theta) assert r3_minusr3_pluseye(3) == eye(3) assert r2_minusr2_pluseye(3) == eye(3) assert r1_minusr1_pluseye(3) == eye(3) # Check the correctness of the trace of the rotation matrix assert r1_plus.trace() == 1 + 2cos(theta) assert r2_plus.trace() == 1 + 2cos(theta) assert r3_plus.trace() == 1 + 2cos(theta) # Check that a rotation with zero angle doesn't change anything. assert rot_axis1(0) == eye(3) assert rot_axis2(0) == eye(3) assert rot_axis3(0) == eye(3) def test_DeferredVector(): assert str(DeferredVector("vector")[4]) == "vector[4]" assert sympify(DeferredVector("d")) == DeferredVector("d") def test_DeferredVector_not_iterable(): assert not iterable(DeferredVector('X')) def test_DeferredVector_Matrix(): raises(TypeError, lambda: Matrix(DeferredVector("V"))) def test_GramSchmidt(): R = Rational m1 = Matrix(1, 2, [1, 2]) m2 = Matrix(1, 2, [2, 3]) assert GramSchmidt([m1, m2]) == \ [Matrix(1, 2, [1, 2]), Matrix(1, 2, [R(2)/5, R(-1)/5])] assert GramSchmidt([m1.T, m2.T]) == \ [Matrix(2, 1, [1, 2]), Matrix(2, 1, [R(2)/5, R(-1)/5])] # from wikipedia assert GramSchmidt([Matrix([3, 1]), Matrix([2, 2])], True) == [ Matrix([3sqrt(10)/10, sqrt(10)/10]), Matrix([-sqrt(10)/10, 3sqrt(10)/10])] def test_casoratian(): assert casoratian([1, 2, 3, 4], 1) == 0 assert casoratian([1, 2, 3, 4], 1, zero=False) == 0 def test_zero_dimension_multiply(): assert (Matrix()zeros(0, 3)).shape == (0, 3) assert zeros(3, 0)zeros(0, 3) == zeros(3, 3) assert zeros(0, 3)zeros(3, 0) == Matrix() def test_slice_issue_2884(): m = Matrix(2, 2, range(4)) assert m[1, :] == Matrix([[2, 3]]) assert m[-1, :] == Matrix([[2, 3]]) assert m[:, 1] == Matrix([[1, 3]]).T assert m[:, -1] == Matrix([[1, 3]]).T raises(IndexError, lambda: m[2, :]) raises(IndexError, lambda: m[2, 2]) def test_slice_issue_3401(): assert zeros(0, 3)[:, -1].shape == (0, 1) assert zeros(3, 0)[0, :] == Matrix(1, 0, []) def test_copyin(): s = zeros(3, 3) s[3] = 1 assert s[:, 0] == Matrix([0, 1, 0]) assert s[3] == 1 assert s[3: 4] == [1] s[1, 1] = 42 assert s[1, 1] == 42 assert s[1, 1:] == Matrix([[42, 0]]) s[1, 1:] = Matrix([[5, 6]]) assert s[1, :] == Matrix([[1, 5, 6]]) s[1, 1:] = [[42, 43]] assert s[1, :] == Matrix([[1, 42, 43]]) s[0, 0] = 17 assert s[:, :1] == Matrix([17, 1, 0]) s[0, 0] = [1, 1, 1] assert s[:, 0] == Matrix([1, 1, 1]) s[0, 0] = Matrix([1, 1, 1]) assert s[:, 0] == Matrix([1, 1, 1]) s[0, 0] = SparseMatrix([1, 1, 1]) assert s[:, 0] == Matrix([1, 1, 1]) def test_invertible_check(): # sometimes a singular matrix will have a pivot vector shorter than # the number of rows in a matrix... assert Matrix([[1, 2], [1, 2]]).rref() == (Matrix([[1, 2], [0, 0]]), (0,)) raises(ValueError, lambda: Matrix([[1, 2], [1, 2]]).inv()) m = Matrix([ [-1, -1, 0], [ x, 1, 1], [ 1, x, -1], ]) assert len(m.rref()[1]) != m.rows # in addition, unless simplify=True in the call to rref, the identity # matrix will be returned even though m is not invertible assert m.rref()[0] != eye(3) assert m.rref(simplify=signsimp)[0] != eye(3) raises(ValueError, lambda: m.inv(method="ADJ")) raises(ValueError, lambda: m.inv(method="GE")) raises(ValueError, lambda: m.inv(method="LU")) @XFAIL def test_issue_3959(): x, y = symbols('x, y') e = xy assert e.subs(x, Matrix([3, 5, 3])) == Matrix([3, 5, 3])y def test_issue_5964(): assert str(Matrix([[1, 2], [3, 4]])) == 'Matrix([[1, 2], [3, 4]])' def test_issue_7604(): x, y = symbols(u"x y") assert sstr(Matrix([[x, 2y], [y2, x + 3]])) == \ 'Matrix([\n[ x, 2y],\n[y*2, x + 3]])' def test_is_Identity(): assert eye(3).is_Identity assert eye(3).as_immutable().is_Identity assert not zeros(3).is_Identity assert not ones(3).is_Identity # issue 6242 assert not Matrix([[1, 0, 0]]).is_Identity # issue 8854 assert SparseMatrix(3,3, {(0,0):1, (1,1):1, (2,2):1}).is_Identity assert not SparseMatrix(2,3, range(6)).is_Identity assert not SparseMatrix(3,3, {(0,0):1, (1,1):1}).is_Identity assert not SparseMatrix(3,3, {(0,0):1, (1,1):1, (2,2):1, (0,1):2, (0,2):3}).is_Identity def test_dot(): assert ones(1, 3).dot(ones(3, 1)) == 3 assert ones(1, 3).dot([1, 1, 1]) == 3 assert Matrix([1, 2, 3]).dot(Matrix([1, 2, 3])) == 14 assert Matrix([1, 2, 3I]).dot(Matrix([I, 2, 3I])) == -5 + I assert Matrix([1, 2, 3I]).dot(Matrix([I, 2, 3I]), hermitian=False) == -5 + I assert Matrix([1, 2, 3I]).dot(Matrix([I, 2, 3I]), hermitian=True) == 13 + I assert Matrix([1, 2, 3I]).dot(Matrix([I, 2, 3I]), hermitian=True, conjugate_convention="physics") == 13 - I assert Matrix([1, 2, 3I]).dot(Matrix([4, 5I, 6]), hermitian=True, conjugate_convention="right") == 4 + 8I assert Matrix([1, 2, 3I]).dot(Matrix([4, 5I, 6]), hermitian=True, conjugate_convention="left") == 4 - 8I assert Matrix([I, 2I]).dot(Matrix([I, 2I]), hermitian=False, conjugate_convention="left") == -5 assert Matrix([I, 2I]).dot(Matrix([I, 2I]), conjugate_convention="left") == 5 def test_dual(): B_x, B_y, B_z, E_x, E_y, E_z = symbols( 'B_x B_y B_z E_x E_y E_z', real=True) F = Matrix(( ( 0, E_x, E_y, E_z), (-E_x, 0, B_z, -B_y), (-E_y, -B_z, 0, B_x), (-E_z, B_y, -B_x, 0) )) Fd = Matrix(( ( 0, -B_x, -B_y, -B_z), (B_x, 0, E_z, -E_y), (B_y, -E_z, 0, E_x), (B_z, E_y, -E_x, 0) )) assert F.dual().equals(Fd) assert eye(3).dual().equals(zeros(3)) assert F.dual().dual().equals(-F) def test_anti_symmetric(): assert Matrix([1, 2]).is_anti_symmetric() is False m = Matrix(3, 3, [0, x2 + 2x + 1, y, -(x + 1)*2, 0, xy, -y, -xy, 0]) assert m.is_anti_symmetric() is True assert m.is_anti_symmetric(simplify=False) is False assert m.is_anti_symmetric(simplify=lambda x: x) is False # tweak to fail m[2, 1] = -m[2, 1] assert m.is_anti_symmetric() is False # untweak m[2, 1] = -m[2, 1] m = m.expand() assert m.is_anti_symmetric(simplify=False) is True m[0, 0] = 1 assert m.is_anti_symmetric() is False def test_normalize_sort_diogonalization(): A = Matrix(((1, 2), (2, 1))) P, Q = A.diagonalize(normalize=True) assert PP.T == P.TP == eye(P.cols) P, Q = A.diagonalize(normalize=True, sort=True) assert PP.T == P.TP == eye(P.cols) assert PQP.inv() == A def test_issue_5321(): raises(ValueError, lambda: Matrix([[1, 2, 3], Matrix(0, 1, [])])) def test_issue_5320(): assert Matrix.hstack(eye(2), 2eye(2)) == Matrix([ [1, 0, 2, 0], [0, 1, 0, 2] ]) assert Matrix.vstack(eye(2), 2eye(2)) == Matrix([ [1, 0], [0, 1], [2, 0], [0, 2] ]) cls = SparseMatrix assert cls.hstack(cls(eye(2)), cls(2eye(2))) == Matrix([ [1, 0, 2, 0], [0, 1, 0, 2] ]) def test_issue_11944(): A = Matrix([[1]]) AIm = sympify(A) assert Matrix.hstack(AIm, A) == Matrix([[1, 1]]) assert Matrix.vstack(AIm, A) == Matrix([[1], [1]]) def test_cross(): a = [1, 2, 3] b = [3, 4, 5] col = Matrix([-2, 4, -2]) row = col.T def test(M, ans): assert ans == M assert type(M) == cls for cls in classes: A = cls(a) B = cls(b) test(A.cross(B), col) test(A.cross(B.T), col) test(A.T.cross(B.T), row) test(A.T.cross(B), row) raises(ShapeError, lambda: Matrix(1, 2, [1, 1]).cross(Matrix(1, 2, [1, 1]))) def test_hash(): for cls in classes[-2:]: s = {cls.eye(1), cls.eye(1)} assert len(s) == 1 and s.pop() == cls.eye(1) # issue 3979 for cls in classes[:2]: assert not isinstance(cls.eye(1), Hashable) @XFAIL def test_issue_3979(): # when this passes, delete this and change the [1:2] # to [:2] in the test_hash above for issue 3979 cls = classes[0] raises(AttributeError, lambda: hash(cls.eye(1))) def test_adjoint(): dat = [[0, I], [1, 0]] ans = Matrix([[0, 1], [-I, 0]]) for cls in classes: assert ans == cls(dat).adjoint() def test_simplify_immutable(): from sympy import simplify, sin, cos assert simplify(ImmutableMatrix([[sin(x)2 + cos(x)2]])) == \ ImmutableMatrix([[1]]) def test_rank(): from sympy.abc import x m = Matrix([[1, 2], [x, 1 - 1/x]]) assert m.rank() == 2 n = Matrix(3, 3, range(1, 10)) assert n.rank() == 2 p = zeros(3) assert p.rank() == 0 def test_issue_11434(): ax, ay, bx, by, cx, cy, dx, dy, ex, ey, t0, t1 = \ symbols('a_x a_y b_x b_y c_x c_y d_x d_y e_x e_y t_0 t_1') M = Matrix([[ax, ay, axt0, ayt0, 0], [bx, by, bxt0, byt0, 0], [cx, cy, cxt0, cyt0, 1], [dx, dy, dxt0, dyt0, 1], [ex, ey, 2ext1 - ext0, 2eyt1 - eyt0, 0]]) assert M.rank() == 4 def test_rank_regression_from_so(): # see: # https://stackoverflow.com/questions/19072700/why-does-sympy-give-me-the-wrong-answer-when-i-row-reduce-a-symbolic-matrix nu, lamb = symbols('nu, lambda') A = Matrix([[-3nu, 1, 0, 0], [ 3nu, -2nu - 1, 2, 0], [ 0, 2nu, (-1nu) - lamb - 2, 3], [ 0, 0, nu + lamb, -3]]) expected_reduced = Matrix([[1, 0, 0, 1/(nu2(-lamb - nu))], [0, 1, 0, 3/(nu(-lamb - nu))], [0, 0, 1, 3/(-lamb - nu)], [0, 0, 0, 0]]) expected_pivots = (0, 1, 2) reduced, pivots = A.rref() assert simplify(expected_reduced - reduced) == zeros(A.shape) assert pivots == expected_pivots def test_replace(): from sympy import symbols, Function, Matrix F, G = symbols('F, G', cls=Function) K = Matrix(2, 2, lambda i, j: G(i+j)) M = Matrix(2, 2, lambda i, j: F(i+j)) N = M.replace(F, G) assert N == K def test_replace_map(): from sympy import symbols, Function, Matrix F, G = symbols('F, G', cls=Function) K = Matrix(2, 2, [(G(0), {F(0): G(0)}), (G(1), {F(1): G(1)}), (G(1), {F(1)\ : G(1)}), (G(2), {F(2): G(2)})]) M = Matrix(2, 2, lambda i, j: F(i+j)) N = M.replace(F, G, True) assert N == K def test_atoms(): m = Matrix([[1, 2], [x, 1 - 1/x]]) assert m.atoms() == {S(1),S(2),S(-1), x} assert m.atoms(Symbol) == {x} @slow def test_pinv(): # Pseudoinverse of an invertible matrix is the inverse. A1 = Matrix([[a, b], [c, d]]) assert simplify(A1.pinv()) == simplify(A1.inv()) # Test the four properties of the pseudoinverse for various matrices. As = [Matrix([[13, 104], [2212, 3], [-3, 5]]), Matrix([[1, 7, 9], [11, 17, 19]]), Matrix([a, b])] for A in As: A_pinv = A.pinv() AAp = A * A_pinv ApA = A_pinv * A assert simplify(AAp * A) == A assert simplify(ApA * A_pinv) == A_pinv assert AAp.H == AAp assert ApA.H == ApA def test_pinv_solve(): # Fully determined system (unique result, identical to other solvers). A = Matrix([[1, 5], [7, 9]]) B = Matrix([12, 13]) assert A.pinv_solve(B) == A.cholesky_solve(B) assert A.pinv_solve(B) == A.LDLsolve(B) assert A.pinv_solve(B) == Matrix([sympify('-43/26'), sympify('71/26')]) assert A * A.pinv() * B == B # Fully determined, with two-dimensional B matrix. B = Matrix([[12, 13, 14], [15, 16, 17]]) assert A.pinv_solve(B) == A.cholesky_solve(B) assert A.pinv_solve(B) == A.LDLsolve(B) assert A.pinv_solve(B) == Matrix([[-33, -37, -41], [69, 75, 81]]) / 26 assert A * A.pinv() * B == B # Underdetermined system (infinite results). A = Matrix([[1, 0, 1], [0, 1, 1]]) B = Matrix([5, 7]) solution = A.pinv_solve(B) w = {} for s in solution.atoms(Symbol): # Extract dummy symbols used in the solution. w[s.name] = s assert solution == Matrix([[w['w0_0']/3 + w['w1_0']/3 - w['w2_0']/3 + 1], [w['w0_0']/3 + w['w1_0']/3 - w['w2_0']/3 + 3], [-w['w0_0']/3 - w['w1_0']/3 + w['w2_0']/3 + 4]]) assert A * A.pinv() * B == B # Overdetermined system (least squares results). A = Matrix([[1, 0], [0, 0], [0, 1]]) B = Matrix([3, 2, 1]) assert A.pinv_solve(B) == Matrix([3, 1]) # Proof the solution is not exact. assert A * A.pinv() * B != B def test_pinv_rank_deficient(): # Test the four properties of the pseudoinverse for various matrices. As = [Matrix([[1, 1, 1], [2, 2, 2]]), Matrix([[1, 0], [0, 0]]), Matrix([[1, 2], [2, 4], [3, 6]])] for A in As: A_pinv = A.pinv() AAp = A * A_pinv ApA = A_pinv * A assert simplify(AAp * A) == A assert simplify(ApA * A_pinv) == A_pinv assert AAp.H == AAp assert ApA.H == ApA # Test solving with rank-deficient matrices. A = Matrix([[1, 0], [0, 0]]) # Exact, non-unique solution. B = Matrix([3, 0]) solution = A.pinv_solve(B) w1 = solution.atoms(Symbol).pop() assert w1.name == 'w1_0' assert solution == Matrix([3, w1]) assert A * A.pinv() * B == B # Least squares, non-unique solution. B = Matrix([3, 1]) solution = A.pinv_solve(B) w1 = solution.atoms(Symbol).pop() assert w1.name == 'w1_0' assert solution == Matrix([3, w1]) assert A * A.pinv() * B != B @XFAIL def test_pinv_rank_deficient_when_diagonalization_fails(): # Test the four properties of the pseudoinverse for matrices when # diagonalization of A.HA fails.' As = [Matrix([ [61, 89, 55, 20, 71, 0], [62, 96, 85, 85, 16, 0], [69, 56, 17, 4, 54, 0], [10, 54, 91, 41, 71, 0], [ 7, 30, 10, 48, 90, 0], [0,0,0,0,0,0]])] for A in As: A_pinv = A.pinv() AAp = A A_pinv ApA = A_pinv * A assert simplify(AAp * A) == A assert simplify(ApA * A_pinv) == A_pinv assert AAp.H == AAp assert ApA.H == ApA def test_gauss_jordan_solve(): # Square, full rank, unique solution A = Matrix([[1, 2, 3], [4, 5, 6], [7, 8, 10]]) b = Matrix([3, 6, 9]) sol, params = A.gauss_jordan_solve(b) assert sol == Matrix([[-1], [2], [0]]) assert params == Matrix(0, 1, []) # Square, reduced rank, parametrized solution A = Matrix([[1, 2, 3], [4, 5, 6], [7, 8, 9]]) b = Matrix([3, 6, 9]) sol, params, freevar = A.gauss_jordan_solve(b, freevar=True) w = {} for s in sol.atoms(Symbol): # Extract dummy symbols used in the solution. w[s.name] = s assert sol == Matrix([[w['tau0'] - 1], [-2w['tau0'] + 2], [w['tau0']]]) assert params == Matrix([[w['tau0']]]) assert freevar == [2] # Square, reduced rank, parametrized solution A = Matrix([[1, 2, 3], [2, 4, 6], [3, 6, 9]]) b = Matrix([0, 0, 0]) sol, params = A.gauss_jordan_solve(b) w = {} for s in sol.atoms(Symbol): w[s.name] = s assert sol == Matrix([[-2w['tau0'] - 3w['tau1']], [w['tau0']], [w['tau1']]]) assert params == Matrix([[w['tau0']], [w['tau1']]]) # Square, reduced rank, parametrized solution A = Matrix([[0, 0, 0], [0, 0, 0], [0, 0, 0]]) b = Matrix([0, 0, 0]) sol, params = A.gauss_jordan_solve(b) w = {} for s in sol.atoms(Symbol): w[s.name] = s assert sol == Matrix([[w['tau0']], [w['tau1']], [w['tau2']]]) assert params == Matrix([[w['tau0']], [w['tau1']], [w['tau2']]]) # Square, reduced rank, no solution A = Matrix([[1, 2, 3], [2, 4, 6], [3, 6, 9]]) b = Matrix([0, 0, 1]) raises(ValueError, lambda: A.gauss_jordan_solve(b)) # Rectangular, tall, full rank, unique solution A = Matrix([[1, 5, 3], [2, 1, 6], [1, 7, 9], [1, 4, 3]]) b = Matrix([0, 0, 1, 0]) sol, params = A.gauss_jordan_solve(b) assert sol == Matrix([[-S(1)/2], [0], [S(1)/6]]) assert params == Matrix(0, 1, []) # Rectangular, tall, full rank, no solution A = Matrix([[1, 5, 3], [2, 1, 6], [1, 7, 9], [1, 4, 3]]) b = Matrix([0, 0, 0, 1]) raises(ValueError, lambda: A.gauss_jordan_solve(b)) # Rectangular, tall, reduced rank, parametrized solution A = Matrix([[1, 5, 3], [2, 10, 6], [3, 15, 9], [1, 4, 3]]) b = Matrix([0, 0, 0, 1]) sol, params = A.gauss_jordan_solve(b) w = {} for s in sol.atoms(Symbol): w[s.name] = s assert sol == Matrix([[-3w['tau0'] + 5], [-1], [w['tau0']]]) assert params == Matrix([[w['tau0']]]) # Rectangular, tall, reduced rank, no solution A = Matrix([[1, 5, 3], [2, 10, 6], [3, 15, 9], [1, 4, 3]]) b = Matrix([0, 0, 1, 1]) raises(ValueError, lambda: A.gauss_jordan_solve(b)) # Rectangular, wide, full rank, parametrized solution A = Matrix([[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 1, 12]]) b = Matrix([1, 1, 1]) sol, params = A.gauss_jordan_solve(b) w = {} for s in sol.atoms(Symbol): w[s.name] = s assert sol == Matrix([[2w['tau0'] - 1], [-3w['tau0'] + 1], [0], [w['tau0']]]) assert params == Matrix([[w['tau0']]]) # Rectangular, wide, reduced rank, parametrized solution A = Matrix([[1, 2, 3, 4], [5, 6, 7, 8], [2, 4, 6, 8]]) b = Matrix([0, 1, 0]) sol, params = A.gauss_jordan_solve(b) w = {} for s in sol.atoms(Symbol): w[s.name] = s assert sol == Matrix([[w['tau0'] + 2w['tau1'] + 1/S(2)], [-2w['tau0'] - 3w['tau1'] - 1/S(4)], [w['tau0']], [w['tau1']]]) assert params == Matrix([[w['tau0']], [w['tau1']]]) # watch out for clashing symbols x0, x1, x2, _x0 = symbols('_tau0 _tau1 _tau2 tau1') M = Matrix([[0, 1, 0, 0, 0, 0], [0, 0, 0, 1, 0, _x0]]) A = M[:, :-1] b = M[:, -1:] sol, params = A.gauss_jordan_solve(b) assert params == Matrix(3, 1, [x0, x1, x2]) assert sol == Matrix(5, 1, [x1, 0, x0, _x0, x2]) # Rectangular, wide, reduced rank, no solution A = Matrix([[1, 2, 3, 4], [5, 6, 7, 8], [2, 4, 6, 8]]) b = Matrix([1, 1, 1]) raises(ValueError, lambda: A.gauss_jordan_solve(b)) def test_solve(): A = Matrix([[1,2], [2,4]]) b = Matrix([[3], [4]]) raises(ValueError, lambda: A.solve(b)) #no solution b = Matrix([[ 4], [8]]) raises(ValueError, lambda: A.solve(b)) #infinite solution def test_issue_7201(): assert ones(0, 1) + ones(0, 1) == Matrix(0, 1, []) assert ones(1, 0) + ones(1, 0) == Matrix(1, 0, []) def test_free_symbols(): for M in ImmutableMatrix, ImmutableSparseMatrix, Matrix, SparseMatrix: assert M([[x], [0]]).free_symbols == {x} def test_from_ndarray(): """See issue 7465.""" try: from numpy import array except ImportError: skip('NumPy must be available to test creating matrices from ndarrays') assert Matrix(array([1, 2, 3])) == Matrix([1, 2, 3]) assert Matrix(array([[1, 2, 3]])) == Matrix([[1, 2, 3]]) assert Matrix(array([[1, 2, 3], [4, 5, 6]])) == \ Matrix([[1, 2, 3], [4, 5, 6]]) assert Matrix(array([x, y, z])) == Matrix([x, y, z]) raises(NotImplementedError, lambda: Matrix(array([[ [1, 2], [3, 4]], [[5, 6], [7, 8]]]))) def test_hermitian(): a = Matrix([[1, I], [-I, 1]]) assert a.is_hermitian a[0, 0] = 2I assert a.is_hermitian is False a[0, 0] = x assert a.is_hermitian is None a[0, 1] = a[1, 0]I assert a.is_hermitian is False def test_doit(): a = Matrix([[Add(x,x, evaluate=False)]]) assert a[0] != 2x assert a.doit() == Matrix([[2x]]) def test_issue_9457_9467_9876(): # for row_del(index) M = Matrix([[1, 2, 3], [2, 3, 4], [3, 4, 5]]) M.row_del(1) assert M == Matrix([[1, 2, 3], [3, 4, 5]]) N = Matrix([[1, 2, 3], [2, 3, 4], [3, 4, 5]]) N.row_del(-2) assert N == Matrix([[1, 2, 3], [3, 4, 5]]) O = Matrix([[1, 2, 3], [5, 6, 7], [9, 10, 11]]) O.row_del(-1) assert O == Matrix([[1, 2, 3], [5, 6, 7]]) P = Matrix([[1, 2, 3], [2, 3, 4], [3, 4, 5]]) raises(IndexError, lambda: P.row_del(10)) Q = Matrix([[1, 2, 3], [2, 3, 4], [3, 4, 5]]) raises(IndexError, lambda: Q.row_del(-10)) # for col_del(index) M = Matrix([[1, 2, 3], [2, 3, 4], [3, 4, 5]]) M.col_del(1) assert M == Matrix([[1, 3], [2, 4], [3, 5]]) N = Matrix([[1, 2, 3], [2, 3, 4], [3, 4, 5]]) N.col_del(-2) assert N == Matrix([[1, 3], [2, 4], [3, 5]]) P = Matrix([[1, 2, 3], [2, 3, 4], [3, 4, 5]]) raises(IndexError, lambda: P.col_del(10)) Q = Matrix([[1, 2, 3], [2, 3, 4], [3, 4, 5]]) raises(IndexError, lambda: Q.col_del(-10)) def test_issue_9422(): x, y = symbols('x y', commutative=False) a, b = symbols('a b') M = eye(2) M1 = Matrix(2, 2, [x, y, y, z]) assert yxM != xyM assert baM == abM assert xM1 != M1x assert aM1 == M1a assert yxM == Matrix([[yx, 0], [0, yx]]) def test_issue_10770(): M = Matrix([]) a = ['col_insert', 'row_join'], Matrix([9, 6, 3]) b = ['row_insert', 'col_join'], a[1].T c = ['row_insert', 'col_insert'], Matrix([[1, 2], [3, 4]]) for ops, m in (a, b, c): for op in ops: f = getattr(M, op) new = f(m) if 'join' in op else f(42, m) assert new == m and id(new) != id(m) def test_issue_10658(): A = Matrix([[1, 2, 3], [4, 5, 6], [7, 8, 9]]) assert A.extract([0, 1, 2], [True, True, False]) == \ Matrix([[1, 2], [4, 5], [7, 8]]) assert A.extract([0, 1, 2], [True, False, False]) == Matrix([[1], [4], [7]]) assert A.extract([True, False, False], [0, 1, 2]) == Matrix([[1, 2, 3]]) assert A.extract([True, False, True], [0, 1, 2]) == \ Matrix([[1, 2, 3], [7, 8, 9]]) assert A.extract([0, 1, 2], [False, False, False]) == Matrix(3, 0, []) assert A.extract([False, False, False], [0, 1, 2]) == Matrix(0, 3, []) assert A.extract([True, False, True], [False, True, False]) == \ Matrix([[2], [8]]) def test_opportunistic_simplification(): # this test relates to issue #10718, #9480, #11434 # issue #9480 m = Matrix([[-5 + 5sqrt(2), -5], [-5sqrt(2)/2 + 5, -5sqrt(2)/2]]) assert m.rank() == 1 # issue #10781 m = Matrix([[3+3sqrt(3)I, -9],[4,-3+3sqrt(3)I]]) assert simplify(m.rref()[0] - Matrix([[1, -9/(3 + 3sqrt(3)I)], [0, 0]])) == zeros(2, 2) # issue #11434 ax,ay,bx,by,cx,cy,dx,dy,ex,ey,t0,t1 = symbols('a_x a_y b_x b_y c_x c_y d_x d_y e_x e_y t_0 t_1') m = Matrix([[ax,ay,axt0,ayt0,0],[bx,by,bxt0,byt0,0],[cx,cy,cxt0,cyt0,1],[dx,dy,dxt0,dyt0,1],[ex,ey,2ext1-ext0,2eyt1-eyt0,0]]) assert m.rank() == 4 def test_partial_pivoting(): # example from https://en.wikipedia.org/wiki/Pivot_element # partial pivoting with back subsitution gives a perfect result # naive pivoting give an error ~1e-13, so anything better than # 1e-15 is good mm=Matrix([[0.003 ,59.14, 59.17],[ 5.291, -6.13,46.78]]) assert (mm.rref()[0] - Matrix([[1.0, 0, 10.0], [ 0, 1.0, 1.0]])).norm() < 1e-15 # issue #11549 m_mixed = Matrix([[6e-17, 1.0, 4],[ -1.0, 0, 8],[ 0, 0, 1]]) m_float = Matrix([[6e-17, 1.0, 4.],[ -1.0, 0., 8.],[ 0., 0., 1.]]) m_inv = Matrix([[ 0, -1.0, 8.0],[1.0, 6.0e-17, -4.0],[ 0, 0, 1]]) # this example is numerically unstable and involves a matrix with a norm >= 8, # this comparing the difference of the results with 1e-15 is numerically sound. assert (m_mixed.inv() - m_inv).norm() < 1e-15 assert (m_float.inv() - m_inv).norm() < 1e-15 def test_iszero_substitution(): """ When doing numerical computations, all elements that pass the iszerofunc test should be set to numerically zero if they aren't already. """ # Matrix from issue #9060 m = Matrix([[0.9, -0.1, -0.2, 0],[-0.8, 0.9, -0.4, 0],[-0.1, -0.8, 0.6, 0]]) m_rref = m.rref(iszerofunc=lambda x: abs(x)<6e-15)[0] m_correct = Matrix([[1.0, 0, -0.301369863013699, 0],[ 0, 1.0, -0.712328767123288, 0],[ 0, 0, 0, 0]]) m_diff = m_rref - m_correct assert m_diff.norm() < 1e-15 # if a zero-substitution wasn't made, this entry will be -1.11022302462516e-16 assert m_rref[2,2] == 0 @slow def test_issue_11238(): from sympy import Point xx = 8tan(13pi/45)/(tan(13pi/45) + sqrt(3)) yy = (-8sqrt(3)tan(13pi/45)*2 + 24tan(13pi/45))/(-3 + tan(13pi/45)*2) p1 = Point(0, 0) p2 = Point(1, -sqrt(3)) p0 = Point(xx,yy) m1 = Matrix([p1 - simplify(p0), p2 - simplify(p0)]) m2 = Matrix([p1 - p0, p2 - p0]) m3 = Matrix([simplify(p1 - p0), simplify(p2 - p0)]) assert m1.rank(simplify=True) == 1 assert m2.rank(simplify=True) == 1 assert m3.rank(simplify=True) == 1 def test_as_real_imag(): m1 = Matrix(2,2,[1,2,3,4]) m2 = m1S.ImaginaryUnit m3 = m1 + m2 for kls in classes: a,b = kls(m3).as_real_imag() assert list(a) == list(m1) assert list(b) == list(m1) def test_deprecated(): # Maintain tests for deprecated functions. We must capture # the deprecation warnings. When the deprecated functionality is # removed, the corresponding tests should be removed. m = Matrix(3, 3, [0, 1, 0, -4, 4, 0, -2, 1, 2]) P, Jcells = m.jordan_cells() assert Jcells[1] == Matrix(1, 1, [2]) assert Jcells[0] == Matrix(2, 2, [2, 1, 0, 2]) with warns_deprecated_sympy(): assert Matrix([[1,2],[3,4]]).dot(Matrix([[1,3],[4,5]])) == [10, 19, 14, 28] def test_issue_14489(): from sympy import Mod A = Matrix([-1, 1, 2]) B = Matrix([10, 20, -15]) assert Mod(A, 3) == Matrix([2, 1, 2]) assert Mod(B, 4) == Matrix([2, 0, 1]) def test_issue_14517(): M = Matrix([ [ 0, 10I, 10I, 0], [10I, 0, 0, 10I], [10I, 0, 5 + 2I, 10I], [ 0, 10I, 10I, 5 + 2I]]) ev = M.eigenvals() # test one random eigenvalue, the computation is a little slow test_ev = random.choice(list(ev.keys())) assert (M - test_ev*eye(4)).det() == 0 def test_issue_14943(): # Test that __array__ accepts the optional dtype argument try: from numpy import array except ImportError: skip('NumPy must be available to test creating matrices from ndarrays') M = Matrix([[1,2], [3,4]]) assert array(M, dtype=float).dtype.name == 'float64' def test_issue_8240(): # Eigenvalues of large triangular matrices n = 200 diagonal_variables = [Symbol('x%s' % i) for i in range(n)] M = [[0 for i in range(n)] for j in range(n)] for i in range(n): M[i][i] = diagonal_variables[i] M = Matrix(M) eigenvals = M.eigenvals() assert len(eigenvals) == n for i in range(n): assert eigenvals[diagonal_variables[i]] == 1 eigenvals = M.eigenvals(multiple=True) assert set(eigenvals) == set(diagonal_variables) # with multiplicity M = Matrix([[x, 0, 0], [1, y, 0], [2, 3, x]]) eigenvals = M.eigenvals() assert eigenvals == {x: 2, y: 1} eigenvals = M.eigenvals(multiple=True) assert len(eigenvals) == 3 assert eigenvals.count(x) == 2 assert eigenvals.count(y) == 1 def test_legacy_det(): # Minimal support for legacy keys for 'method' in det() # Partially copied from test_determinant() M = Matrix(( ( 3, -2, 0, 5), (-2, 1, -2, 2), ( 0, -2, 5, 0), ( 5, 0, 3, 4) )) assert M.det(method="bareis") == -289 assert M.det(method="det_lu") == -289 assert M.det(method="det_LU") == -289 M = Matrix(( (3, 2, 0, 0, 0), (0, 3, 2, 0, 0), (0, 0, 3, 2, 0), (0, 0, 0, 3, 2), (2, 0, 0, 0, 3) )) assert M.det(method="bareis") == 275 assert M.det(method="det_lu") == 275 assert M.det(method="Bareis") == 275 M = Matrix(( (1, 0, 1, 2, 12), (2, 0, 1, 1, 4), (2, 1, 1, -1, 3), (3, 2, -1, 1, 8), (1, 1, 1, 0, 6) )) assert M.det(method="bareis") == -55 assert M.det(method="det_lu") == -55 assert M.det(method="BAREISS") == -55 M = Matrix(( (-5, 2, 3, 4, 5), ( 1, -4, 3, 4, 5), ( 1, 2, -3, 4, 5), ( 1, 2, 3, -2, 5), ( 1, 2, 3, 4, -1) )) assert M.det(method="bareis") == 11664 assert M.det(method="det_lu") == 11664 assert M.det(method="BERKOWITZ") == 11664 M = Matrix(( ( 2, 7, -1, 3, 2), ( 0, 0, 1, 0, 1), (-2, 0, 7, 0, 2), (-3, -2, 4, 5, 3), ( 1, 0, 0, 0, 1) )) assert M.det(method="bareis") == 123 assert M.det(method="det_lu") == 123 assert M.det(method="LU") == 123
d27b60d162336cf52bd4c3e709a4e0f5b446f6d8167cac516f2f03c8263bd5f7	from sympy.matrices.expressions import MatrixExpr from sympy import MatrixBase class ElementwiseApplyFunction(MatrixExpr): r""" Apply function to a matrix elementwise without evaluating. Examples ======== >>> from sympy.matrices.expressions import MatrixSymbol >>> from sympy.matrices.expressions.applyfunc import ElementwiseApplyFunction >>> from sympy import exp >>> X = MatrixSymbol("X", 3, 3) >>> X.applyfunc(exp) ElementwiseApplyFunction(exp, X) >>> from sympy import eye >>> expr = ElementwiseApplyFunction(exp, eye(3)) >>> expr ElementwiseApplyFunction(exp, Matrix([ [1, 0, 0], [0, 1, 0], [0, 0, 1]])) >>> expr.doit() Matrix([ [E, 1, 1], [1, E, 1], [1, 1, E]]) Notice the difference with the real mathematical functions: >>> exp(eye(3)) Matrix([ [E, 0, 0], [0, E, 0], [0, 0, E]]) """ def __new__(cls, function, expr): obj = MatrixExpr.__new__(cls, function, expr) obj._function = function obj._expr = expr return obj @property def function(self): return self._function @property def expr(self): return self._expr @property def shape(self): return self.expr.shape def doit(self, kwargs): deep = kwargs.get("deep", True) expr = self.expr if deep: expr = expr.doit(kwargs) if isinstance(expr, MatrixBase): return expr.applyfunc(self.function) else: return self
ca1018abf5435bd0e28bf8cf0f576a176e375e33e1616fbbbfc099ab48d904bb	from __future__ import print_function, division from sympy.core.sympify import _sympify from sympy.core import S, Basic from sympy.matrices.expressions.matexpr import ShapeError from sympy.matrices.expressions.matpow import MatPow class Inverse(MatPow): """ The multiplicative inverse of a matrix expression This is a symbolic object that simply stores its argument without evaluating it. To actually compute the inverse, use the ``.inverse()`` method of matrices. Examples ======== >>> from sympy import MatrixSymbol, Inverse >>> A = MatrixSymbol('A', 3, 3) >>> B = MatrixSymbol('B', 3, 3) >>> Inverse(A) A*(-1) >>> A.inverse() == Inverse(A) True >>> (AB).inverse() B*(-1)A*(-1) >>> Inverse(AB) (AB)(-1) """ is_Inverse = True exp = S(-1) def __new__(cls, mat, exp=S(-1)): # exp is there to make it consistent with # inverse.func(inverse.args) == inverse mat = _sympify(mat) if not mat.is_Matrix: raise TypeError("mat should be a matrix") if not mat.is_square: raise ShapeError("Inverse of non-square matrix %s" % mat) return Basic.__new__(cls, mat, exp) @property def arg(self): return self.args[0] @property def shape(self): return self.arg.shape def _eval_inverse(self): return self.arg def _eval_determinant(self): from sympy.matrices.expressions.determinant import det return 1/det(self.arg) def doit(self, hints): if 'inv_expand' in hints and hints['inv_expand'] == False: return self if hints.get('deep', True): return self.arg.doit(hints).inverse() else: return self.arg.inverse() def _eval_derivative_matrix_lines(self, x): arg = self.args[0] lines = arg._eval_derivative_matrix_lines(x) for line in lines: if line.transposed: line.first = self line.second = -self.T else: line.first = -self.T line.second = self return lines from sympy.assumptions.ask import ask, Q from sympy.assumptions.refine import handlers_dict def refine_Inverse(expr, assumptions): """ >>> from sympy import MatrixSymbol, Q, assuming, refine >>> X = MatrixSymbol('X', 2, 2) >>> X.I X**(-1) >>> with assuming(Q.orthogonal(X)): ... print(refine(X.I)) X.T """ if ask(Q.orthogonal(expr), assumptions): return expr.arg.T elif ask(Q.unitary(expr), assumptions): return expr.arg.conjugate() elif ask(Q.singular(expr), assumptions): raise ValueError("Inverse of singular matrix %s" % expr.arg) return expr handlers_dict['Inverse'] = refine_Inverse
ef08ed0ffb603901a8de99625350ad432cda93da60d7015de9d7565575361ad1	from __future__ import print_function, division from sympy import Basic from sympy.functions import adjoint, conjugate from sympy.matrices.expressions.matexpr import MatrixExpr class Transpose(MatrixExpr): """ The transpose of a matrix expression. This is a symbolic object that simply stores its argument without evaluating it. To actually compute the transpose, use the ``transpose()`` function, or the ``.T`` attribute of matrices. Examples ======== >>> from sympy.matrices import MatrixSymbol, Transpose >>> from sympy.functions import transpose >>> A = MatrixSymbol('A', 3, 5) >>> B = MatrixSymbol('B', 5, 3) >>> Transpose(A) A.T >>> A.T == transpose(A) == Transpose(A) True >>> Transpose(AB) (AB).T >>> transpose(AB) B.TA.T """ is_Transpose = True def doit(self, hints): arg = self.arg if hints.get('deep', True) and isinstance(arg, Basic): arg = arg.doit(hints) try: result = arg._eval_transpose() return result if result is not None else Transpose(arg) except AttributeError: return Transpose(arg) @property def arg(self): return self.args[0] @property def shape(self): return self.arg.shape[::-1] def _entry(self, i, j, expand=False): return self.arg._entry(j, i, expand=expand) def _eval_adjoint(self): return conjugate(self.arg) def _eval_conjugate(self): return adjoint(self.arg) def _eval_transpose(self): return self.arg def _eval_trace(self): from .trace import Trace return Trace(self.arg) # Trace(X.T) => Trace(X) def _eval_determinant(self): from sympy.matrices.expressions.determinant import det return det(self.arg) def _eval_derivative_matrix_lines(self, x): lines = self.args[0]._eval_derivative_matrix_lines(x) return [i.transpose() for i in lines] def transpose(expr): """Matrix transpose""" return Transpose(expr).doit(deep=False) from sympy.assumptions.ask import ask, Q from sympy.assumptions.refine import handlers_dict def refine_Transpose(expr, assumptions): """ >>> from sympy import MatrixSymbol, Q, assuming, refine >>> X = MatrixSymbol('X', 2, 2) >>> X.T X.T >>> with assuming(Q.symmetric(X)): ... print(refine(X.T)) X """ if ask(Q.symmetric(expr), assumptions): return expr.arg return expr handlers_dict['Transpose'] = refine_Transpose
0137c28bf1080b2ada5981185a67320f23d829449d8a86eae9f0952051c7cb18	from __future__ import print_function, division from sympy import Number from sympy.core import Mul, Basic, sympify, Add from sympy.core.compatibility import range from sympy.functions import adjoint from sympy.matrices.expressions.transpose import transpose from sympy.strategies import (rm_id, unpack, typed, flatten, exhaust, do_one, new) from sympy.matrices.expressions.matexpr import (MatrixExpr, ShapeError, Identity, ZeroMatrix) from sympy.matrices.expressions.matpow import MatPow from sympy.matrices.matrices import MatrixBase class MatMul(MatrixExpr, Mul): """ A product of matrix expressions Examples ======== >>> from sympy import MatMul, MatrixSymbol >>> A = MatrixSymbol('A', 5, 4) >>> B = MatrixSymbol('B', 4, 3) >>> C = MatrixSymbol('C', 3, 6) >>> MatMul(A, B, C) ABC """ is_MatMul = True def __new__(cls, args, kwargs): check = kwargs.get('check', True) args = list(map(sympify, args)) obj = Basic.__new__(cls, args) factor, matrices = obj.as_coeff_matrices() if check: validate(matrices) if not matrices: return factor return obj @property def shape(self): matrices = [arg for arg in self.args if arg.is_Matrix] return (matrices[0].rows, matrices[-1].cols) def _entry(self, i, j, expand=True): from sympy import Dummy, Sum, Mul, ImmutableMatrix, Integer coeff, matrices = self.as_coeff_matrices() if len(matrices) == 1: # situation like 2X, matmul is just X return coeff * matrices[0][i, j] indices = [None](len(matrices) + 1) ind_ranges = [None](len(matrices) - 1) indices[0] = i indices[-1] = j for i in range(1, len(matrices)): indices[i] = Dummy("i_%i" % i) for i, arg in enumerate(matrices[:-1]): ind_ranges[i] = arg.shape[1] - 1 matrices = [arg[indices[i], indices[i+1]] for i, arg in enumerate(matrices)] expr_in_sum = Mul.fromiter(matrices) if any(v.has(ImmutableMatrix) for v in matrices): expand = True result = coeffSum( expr_in_sum, zip(indices[1:-1], [0]len(ind_ranges), ind_ranges) ) # Don't waste time in result.doit() if the sum bounds are symbolic if not any(isinstance(v, (Integer, int)) for v in ind_ranges): expand = False return result.doit() if expand else result def as_coeff_matrices(self): scalars = [x for x in self.args if not x.is_Matrix] matrices = [x for x in self.args if x.is_Matrix] coeff = Mul(scalars) return coeff, matrices def as_coeff_mmul(self): coeff, matrices = self.as_coeff_matrices() return coeff, MatMul(matrices) def _eval_transpose(self): return MatMul([transpose(arg) for arg in self.args[::-1]]).doit() def _eval_adjoint(self): return MatMul([adjoint(arg) for arg in self.args[::-1]]).doit() def _eval_trace(self): factor, mmul = self.as_coeff_mmul() if factor != 1: from .trace import trace return factor trace(mmul.doit()) else: raise NotImplementedError("Can't simplify any further") def _eval_determinant(self): from sympy.matrices.expressions.determinant import Determinant factor, matrices = self.as_coeff_matrices() square_matrices = only_squares(matrices) return factorself.rows Mul(list(map(Determinant, square_matrices))) def _eval_inverse(self): try: return MatMul([ arg.inverse() if isinstance(arg, MatrixExpr) else arg-1 for arg in self.args[::-1]]).doit() except ShapeError: from sympy.matrices.expressions.inverse import Inverse return Inverse(self) def doit(self, kwargs): deep = kwargs.get('deep', True) if deep: args = [arg.doit(*kwargs) for arg in self.args] else: args = self.args # treat scalarMatrixSymbol or scalarMatPow separately mats = [arg for arg in self.args if arg.is_Matrix] expr = canonicalize(MatMul(args)) return expr # Needed for partial compatibility with Mul def args_cnc(self, kwargs): coeff, matrices = self.as_coeff_matrices() # I don't know how coeff could have noncommutative factors, but this # handles it. coeff_c, coeff_nc = coeff.args_cnc(kwargs) return coeff_c, coeff_nc + matrices def _eval_derivative_matrix_lines(self, x): from .transpose import Transpose with_x_ind = [i for i, arg in enumerate(self.args) if arg.has(x)] lines = [] for ind in with_x_ind: left_args = self.args[:ind] right_args = self.args[ind+1:] right_mat = MatMul.fromiter(right_args) right_rev = MatMul.fromiter([Transpose(i).doit() for i in reversed(right_args)]) left_mat = MatMul.fromiter(left_args) left_rev = MatMul.fromiter([Transpose(i).doit() for i in reversed(left_args)]) d = self.args[ind]._eval_derivative_matrix_lines(x) for i in d: if i.transposed: i.append_first(right_mat) i.append_second(left_rev) else: i.append_first(left_rev) i.append_second(right_mat) lines.append(i) return lines def validate(matrices): """ Checks for valid shapes for args of MatMul """ for i in range(len(matrices)-1): A, B = matrices[i:i+2] if A.cols != B.rows: raise ShapeError("Matrices %s and %s are not aligned"%(A, B)) # Rules def newmul(args): if args[0] == 1: args = args[1:] return new(MatMul, args) def any_zeros(mul): if any([arg.is_zero or (arg.is_Matrix and arg.is_ZeroMatrix) for arg in mul.args]): matrices = [arg for arg in mul.args if arg.is_Matrix] return ZeroMatrix(matrices[0].rows, matrices[-1].cols) return mul def merge_explicit(matmul): """ Merge explicit MatrixBase arguments >>> from sympy import MatrixSymbol, eye, Matrix, MatMul, pprint >>> from sympy.matrices.expressions.matmul import merge_explicit >>> A = MatrixSymbol('A', 2, 2) >>> B = Matrix([[1, 1], [1, 1]]) >>> C = Matrix([[1, 2], [3, 4]]) >>> X = MatMul(A, B, C) >>> pprint(X) [1 1] [1 2] A[ ][ ] [1 1] [3 4] >>> pprint(merge_explicit(X)) [4 6] A[ ] [4 6] >>> X = MatMul(B, A, C) >>> pprint(X) [1 1] [1 2] [ ]A[ ] [1 1] [3 4] >>> pprint(merge_explicit(X)) [1 1] [1 2] [ ]A[ ] [1 1] [3 4] """ if not any(isinstance(arg, MatrixBase) for arg in matmul.args): return matmul newargs = [] last = matmul.args[0] for arg in matmul.args[1:]: if isinstance(arg, (MatrixBase, Number)) and isinstance(last, (MatrixBase, Number)): last = last * arg else: newargs.append(last) last = arg newargs.append(last) return MatMul(newargs) def xxinv(mul): """ Y X * X.I -> Y """ from sympy.matrices.expressions.inverse import Inverse factor, matrices = mul.as_coeff_matrices() for i, (X, Y) in enumerate(zip(matrices[:-1], matrices[1:])): try: if X.is_square and Y.is_square: _X, x_exp = X, 1 _Y, y_exp = Y, 1 if isinstance(X, MatPow) and not isinstance(X, Inverse): _X, x_exp = X.args if isinstance(Y, MatPow) and not isinstance(Y, Inverse): _Y, y_exp = Y.args if _X == _Y.inverse(): if x_exp - y_exp > 0: I = _X(x_exp-y_exp) else: I = _Y(y_exp-x_exp) return newmul(factor, (matrices[:i] + [I] + matrices[i+2:])) except ValueError: # Y might not be invertible pass return mul def remove_ids(mul): """ Remove Identities from a MatMul This is a modified version of sympy.strategies.rm_id. This is necesssary because MatMul may contain both MatrixExprs and Exprs as args. See Also ======== sympy.strategies.rm_id """ # Separate Exprs from MatrixExprs in args factor, mmul = mul.as_coeff_mmul() # Apply standard rm_id for MatMuls result = rm_id(lambda x: x.is_Identity is True)(mmul) if result != mmul: return newmul(factor, result.args) # Recombine and return else: return mul def factor_in_front(mul): factor, matrices = mul.as_coeff_matrices() if factor != 1: return newmul(factor, matrices) return mul def combine_powers(mul): # combine consecutive powers with the same base into one # e.g. AA2 -> A3 from sympy.matrices.expressions import MatPow factor, mmul = mul.as_coeff_mmul() args = [] base = None exp = 0 for arg in mmul.args: if isinstance(arg, MatPow): current_base = arg.args[0] current_exp = arg.args[1] else: current_base = arg current_exp = 1 if current_base == base: exp += current_exp else: if not base is None: if exp == 1: args.append(base) else: args.append(baseexp) exp = current_exp base = current_base if exp == 1: args.append(base) else: args.append(baseexp) return newmul(factor, args) rules = (any_zeros, remove_ids, xxinv, unpack, rm_id(lambda x: x == 1), merge_explicit, factor_in_front, flatten, combine_powers) canonicalize = exhaust(typed({MatMul: do_one(rules)})) def only_squares(matrices): """factor matrices only if they are square""" if matrices[0].rows != matrices[-1].cols: raise RuntimeError("Invalid matrices being multiplied") out = [] start = 0 for i, M in enumerate(matrices): if M.cols == matrices[start].rows: out.append(MatMul(matrices[start:i+1]).doit()) start = i+1 return out from sympy.assumptions.ask import ask, Q from sympy.assumptions.refine import handlers_dict def refine_MatMul(expr, assumptions): """ >>> from sympy import MatrixSymbol, Q, assuming, refine >>> X = MatrixSymbol('X', 2, 2) >>> expr = X * X.T >>> print(expr) XX.T >>> with assuming(Q.orthogonal(X)): ... print(refine(expr)) I """ newargs = [] exprargs = [] for args in expr.args: if args.is_Matrix: exprargs.append(args) else: newargs.append(args) last = exprargs[0] for arg in exprargs[1:]: if arg == last.T and ask(Q.orthogonal(arg), assumptions): last = Identity(arg.shape[0]) elif arg == last.conjugate() and ask(Q.unitary(arg), assumptions): last = Identity(arg.shape[0]) else: newargs.append(last) last = arg newargs.append(last) return MatMul(newargs) handlers_dict['MatMul'] = refine_MatMul
115e647f64a86f161c642aabef3f8772a4eeadd4c5b8613e95012f33975f7e15	from __future__ import print_function, division from .matexpr import MatrixExpr, ShapeError, Identity, ZeroMatrix from .transpose import Transpose from sympy.core.sympify import _sympify from sympy.core.compatibility import range from sympy.matrices import MatrixBase from sympy.core import S, Basic class MatPow(MatrixExpr): def __new__(cls, base, exp): base = _sympify(base) if not base.is_Matrix: raise TypeError("Function parameter should be a matrix") exp = _sympify(exp) return super(MatPow, cls).__new__(cls, base, exp) @property def base(self): return self.args[0] @property def exp(self): return self.args[1] @property def shape(self): return self.base.shape def _entry(self, i, j, *kwargs): from sympy.matrices.expressions import MatMul A = self.doit() if isinstance(A, MatPow): # We still have a MatPow, make an explicit MatMul out of it. if not A.base.is_square: raise ShapeError("Power of non-square matrix %s" % A.base) elif A.exp.is_Integer and A.exp.is_positive: A = MatMul([A.base for k in range(A.exp)]) #elif A.exp.is_Integer and self.exp.is_negative: # Note: possible future improvement: in principle we can take # positive powers of the inverse, but carefully avoid recursion, # perhaps by adding `_entry` to Inverse (as it is our subclass). # T = A.base.as_explicit().inverse() # A = MatMul([T for k in range(-A.exp)]) else: # Leave the expression unevaluated: from sympy.matrices.expressions.matexpr import MatrixElement return MatrixElement(self, i, j) return A._entry(i, j) def doit(self, kwargs): from sympy.matrices.expressions import Inverse deep = kwargs.get('deep', True) if deep: args = [arg.doit(kwargs) for arg in self.args] else: args = self.args base, exp = args # combine all powers, e.g. (A2)3 = A6 while isinstance(base, MatPow): exp = expbase.args[1] base = base.args[0] if exp.is_zero and base.is_square: if isinstance(base, MatrixBase): return base.func(Identity(base.shape[0])) return Identity(base.shape[0]) elif isinstance(base, ZeroMatrix) and exp.is_negative: raise ValueError("Matrix determinant is 0, not invertible.") elif isinstance(base, (Identity, ZeroMatrix)): return base elif isinstance(base, MatrixBase) and exp.is_number: if exp is S.One: return base return baseexp # Note: just evaluate cases we know, return unevaluated on others. # E.g., MatrixSymbol('x', n, m) to power 0 is not an error. elif exp is S(-1) and base.is_square: return Inverse(base).doit(kwargs) elif exp is S.One: return base return MatPow(base, exp) def _eval_transpose(self): base, exp = self.args return MatPow(base.T, exp) def _eval_derivative_matrix_lines(self, x): from .matmul import MatMul exp = self.exp if (exp > 0) == True: newexpr = MatMul.fromiter([self.base for i in range(exp)]) elif (exp == -1) == True: return Inverse(self.base)._eval_derivative_matrix_lines(x) elif (exp < 0) == True: newexpr = MatMul.fromiter([Inverse(self.base) for i in range(-exp)]) elif (exp == 0) == True: return self.doit()._eval_derivative_matrix_lines(x) else: raise NotImplementedError("cannot evaluate %s derived by %s" % (self, x)) return newexpr._eval_derivative_matrix_lines(x)
1efd7be8d555fbbb531e38561e8e80a402d59d8df75f800704cfa8edf3dcf7e2	from __future__ import print_function, division from functools import wraps, reduce import collections from sympy.core import S, Symbol, Tuple, Integer, Basic, Expr, Eq from sympy.core.decorators import call_highest_priority from sympy.core.compatibility import range, SYMPY_INTS, default_sort_key from sympy.core.sympify import SympifyError, sympify from sympy.functions import conjugate, adjoint from sympy.functions.special.tensor_functions import KroneckerDelta from sympy.matrices import ShapeError from sympy.simplify import simplify from sympy.utilities.misc import filldedent def _sympifyit(arg, retval=None): # This version of _sympifyit sympifies MutableMatrix objects def deco(func): @wraps(func) def __sympifyit_wrapper(a, b): try: b = sympify(b, strict=True) return func(a, b) except SympifyError: return retval return __sympifyit_wrapper return deco class MatrixExpr(Expr): """Superclass for Matrix Expressions MatrixExprs represent abstract matrices, linear transformations represented within a particular basis. Examples ======== >>> from sympy import MatrixSymbol >>> A = MatrixSymbol('A', 3, 3) >>> y = MatrixSymbol('y', 3, 1) >>> x = (A.TA).I A * y See Also ======== MatrixSymbol, MatAdd, MatMul, Transpose, Inverse """ # Should not be considered iterable by the # sympy.core.compatibility.iterable function. Subclass that actually are # iterable (i.e., explicit matrices) should set this to True. _iterable = False _op_priority = 11.0 is_Matrix = True is_MatrixExpr = True is_Identity = None is_Inverse = False is_Transpose = False is_ZeroMatrix = False is_MatAdd = False is_MatMul = False is_commutative = False is_number = False is_symbol = False def __new__(cls, args, kwargs): args = map(sympify, args) return Basic.__new__(cls, args, *kwargs) # The following is adapted from the core Expr object def __neg__(self): return MatMul(S.NegativeOne, self).doit() def __abs__(self): raise NotImplementedError @_sympifyit('other', NotImplemented) @call_highest_priority('__radd__') def __add__(self, other): return MatAdd(self, other, check=True).doit() @_sympifyit('other', NotImplemented) @call_highest_priority('__add__') def __radd__(self, other): return MatAdd(other, self, check=True).doit() @_sympifyit('other', NotImplemented) @call_highest_priority('__rsub__') def __sub__(self, other): return MatAdd(self, -other, check=True).doit() @_sympifyit('other', NotImplemented) @call_highest_priority('__sub__') def __rsub__(self, other): return MatAdd(other, -self, check=True).doit() @_sympifyit('other', NotImplemented) @call_highest_priority('__rmul__') def __mul__(self, other): return MatMul(self, other).doit() @_sympifyit('other', NotImplemented) @call_highest_priority('__rmul__') def __matmul__(self, other): return MatMul(self, other).doit() @_sympifyit('other', NotImplemented) @call_highest_priority('__mul__') def __rmul__(self, other): return MatMul(other, self).doit() @_sympifyit('other', NotImplemented) @call_highest_priority('__mul__') def __rmatmul__(self, other): return MatMul(other, self).doit() @_sympifyit('other', NotImplemented) @call_highest_priority('__rpow__') def __pow__(self, other): if not self.is_square: raise ShapeError("Power of non-square matrix %s" % self) elif self.is_Identity: return self elif other is S.Zero: return Identity(self.rows) elif other is S.One: return self return MatPow(self, other).doit(deep=False) @_sympifyit('other', NotImplemented) @call_highest_priority('__pow__') def __rpow__(self, other): raise NotImplementedError("Matrix Power not defined") @_sympifyit('other', NotImplemented) @call_highest_priority('__rdiv__') def __div__(self, other): return self other*S.NegativeOne @_sympifyit('other', NotImplemented) @call_highest_priority('__div__') def __rdiv__(self, other): raise NotImplementedError() #return MatMul(other, Pow(self, S.NegativeOne)) __truediv__ = __div__ __rtruediv__ = __rdiv__ @property def rows(self): return self.shape[0] @property def cols(self): return self.shape[1] @property def is_square(self): return self.rows == self.cols def _eval_conjugate(self): from sympy.matrices.expressions.adjoint import Adjoint from sympy.matrices.expressions.transpose import Transpose return Adjoint(Transpose(self)) def as_real_imag(self): from sympy import I real = (S(1)/2) (self + self._eval_conjugate()) im = (self - self._eval_conjugate())/(2I) return (real, im) def _eval_inverse(self): from sympy.matrices.expressions.inverse import Inverse return Inverse(self) def _eval_transpose(self): return Transpose(self) def _eval_power(self, exp): return MatPow(self, exp) def _eval_simplify(self, kwargs): if self.is_Atom: return self else: return self.__class__([simplify(x, kwargs) for x in self.args]) def _eval_adjoint(self): from sympy.matrices.expressions.adjoint import Adjoint return Adjoint(self) def _eval_derivative(self, x): return _matrix_derivative(self, x) def _eval_derivative_n_times(self, x, n): return Basic._eval_derivative_n_times(self, x, n) def _entry(self, i, j, kwargs): raise NotImplementedError( "Indexing not implemented for %s" % self.__class__.__name__) def adjoint(self): return adjoint(self) def as_coeff_Mul(self, rational=False): """Efficiently extract the coefficient of a product. """ return S.One, self def conjugate(self): return conjugate(self) def transpose(self): from sympy.matrices.expressions.transpose import transpose return transpose(self) T = property(transpose, None, None, 'Matrix transposition.') def inverse(self): return self._eval_inverse() inv = inverse @property def I(self): return self.inverse() def valid_index(self, i, j): def is_valid(idx): return isinstance(idx, (int, Integer, Symbol, Expr)) return (is_valid(i) and is_valid(j) and (self.rows is None or (0 <= i) != False and (i < self.rows) != False) and (0 <= j) != False and (j < self.cols) != False) def __getitem__(self, key): if not isinstance(key, tuple) and isinstance(key, slice): from sympy.matrices.expressions.slice import MatrixSlice return MatrixSlice(self, key, (0, None, 1)) if isinstance(key, tuple) and len(key) == 2: i, j = key if isinstance(i, slice) or isinstance(j, slice): from sympy.matrices.expressions.slice import MatrixSlice return MatrixSlice(self, i, j) i, j = sympify(i), sympify(j) if self.valid_index(i, j) != False: return self._entry(i, j) else: raise IndexError("Invalid indices (%s, %s)" % (i, j)) elif isinstance(key, (SYMPY_INTS, Integer)): # row-wise decomposition of matrix rows, cols = self.shape # allow single indexing if number of columns is known if not isinstance(cols, Integer): raise IndexError(filldedent(''' Single indexing is only supported when the number of columns is known.''')) key = sympify(key) i = key // cols j = key % cols if self.valid_index(i, j) != False: return self._entry(i, j) else: raise IndexError("Invalid index %s" % key) elif isinstance(key, (Symbol, Expr)): raise IndexError(filldedent(''' Only integers may be used when addressing the matrix with a single index.''')) raise IndexError("Invalid index, wanted %s[i,j]" % self) def as_explicit(self): """ Returns a dense Matrix with elements represented explicitly Returns an object of type ImmutableDenseMatrix. Examples ======== >>> from sympy import Identity >>> I = Identity(3) >>> I I >>> I.as_explicit() Matrix([ [1, 0, 0], [0, 1, 0], [0, 0, 1]]) See Also ======== as_mutable: returns mutable Matrix type """ from sympy.matrices.immutable import ImmutableDenseMatrix return ImmutableDenseMatrix([[ self[i, j] for j in range(self.cols)] for i in range(self.rows)]) def as_mutable(self): """ Returns a dense, mutable matrix with elements represented explicitly Examples ======== >>> from sympy import Identity >>> I = Identity(3) >>> I I >>> I.shape (3, 3) >>> I.as_mutable() Matrix([ [1, 0, 0], [0, 1, 0], [0, 0, 1]]) See Also ======== as_explicit: returns ImmutableDenseMatrix """ return self.as_explicit().as_mutable() def __array__(self): from numpy import empty a = empty(self.shape, dtype=object) for i in range(self.rows): for j in range(self.cols): a[i, j] = self[i, j] return a def equals(self, other): """ Test elementwise equality between matrices, potentially of different types >>> from sympy import Identity, eye >>> Identity(3).equals(eye(3)) True """ return self.as_explicit().equals(other) def canonicalize(self): return self def as_coeff_mmul(self): return 1, MatMul(self) @staticmethod def from_index_summation(expr, first_index=None, last_index=None, dimensions=None): r""" Parse expression of matrices with explicitly summed indices into a matrix expression without indices, if possible. This transformation expressed in mathematical notation: `\sum_{j=0}^{N-1} A_{i,j} B_{j,k} \Longrightarrow \mathbf{A}\cdot \mathbf{B}` Optional parameter ``first_index``: specify which free index to use as the index starting the expression. Examples ======== >>> from sympy import MatrixSymbol, MatrixExpr, Sum, Symbol >>> from sympy.abc import i, j, k, l, N >>> A = MatrixSymbol("A", N, N) >>> B = MatrixSymbol("B", N, N) >>> expr = Sum(A[i, j]B[j, k], (j, 0, N-1)) >>> MatrixExpr.from_index_summation(expr) AB Transposition is detected: >>> expr = Sum(A[j, i]B[j, k], (j, 0, N-1)) >>> MatrixExpr.from_index_summation(expr) A.TB Detect the trace: >>> expr = Sum(A[i, i], (i, 0, N-1)) >>> MatrixExpr.from_index_summation(expr) Trace(A) More complicated expressions: >>> expr = Sum(A[i, j]B[k, j]A[l, k], (j, 0, N-1), (k, 0, N-1)) >>> MatrixExpr.from_index_summation(expr) AB.TA.T """ from sympy import Sum, Mul, Add, MatMul, transpose, trace from sympy.strategies.traverse import bottom_up def remove_matelement(expr, i1, i2): def repl_match(pos): def func(x): if not isinstance(x, MatrixElement): return False if x.args[pos] != i1: return False if x.args[3-pos] == 0: if x.args[0].shape[2-pos] == 1: return True else: return False return True return func expr = expr.replace(repl_match(1), lambda x: x.args[0]) expr = expr.replace(repl_match(2), lambda x: transpose(x.args[0])) # Make sure that all Mul are transformed to MatMul and that they # are flattened: rule = bottom_up(lambda x: reduce(lambda a, b: ab, x.args) if isinstance(x, (Mul, MatMul)) else x) return rule(expr) def recurse_expr(expr, index_ranges={}): if expr.is_Mul: nonmatargs = [] pos_arg = [] pos_ind = [] dlinks = {} link_ind = [] counter = 0 args_ind = [] for arg in expr.args: retvals = recurse_expr(arg, index_ranges) assert isinstance(retvals, list) if isinstance(retvals, list): for i in retvals: args_ind.append(i) else: args_ind.append(retvals) for arg_symbol, arg_indices in args_ind: if arg_indices is None: nonmatargs.append(arg_symbol) continue if isinstance(arg_symbol, MatrixElement): arg_symbol = arg_symbol.args[0] pos_arg.append(arg_symbol) pos_ind.append(arg_indices) link_ind.append([None]len(arg_indices)) for i, ind in enumerate(arg_indices): if ind in dlinks: other_i = dlinks[ind] link_ind[counter][i] = other_i link_ind[other_i[0]][other_i[1]] = (counter, i) dlinks[ind] = (counter, i) counter += 1 counter2 = 0 lines = {} while counter2 < len(link_ind): for i, e in enumerate(link_ind): if None in e: line_start_index = (i, e.index(None)) break cur_ind_pos = line_start_index cur_line = [] index1 = pos_ind[cur_ind_pos[0]][cur_ind_pos[1]] while True: d, r = cur_ind_pos if pos_arg[d] != 1: if r % 2 == 1: cur_line.append(transpose(pos_arg[d])) else: cur_line.append(pos_arg[d]) next_ind_pos = link_ind[d][1-r] counter2 += 1 # Mark as visited, there will be no `None` anymore: link_ind[d] = (-1, -1) if next_ind_pos is None: index2 = pos_ind[d][1-r] lines[(index1, index2)] = cur_line break cur_ind_pos = next_ind_pos ret_indices = list(j for i in lines for j in i) lines = {k: MatMul.fromiter(v) if len(v) != 1 else v[0] for k, v in lines.items()} return [(Mul.fromiter(nonmatargs), None)] + [ (MatrixElement(a, i, j), (i, j)) for (i, j), a in lines.items() ] elif expr.is_Add: res = [recurse_expr(i) for i in expr.args] d = collections.defaultdict(list) for res_addend in res: scalar = 1 for elem, indices in res_addend: if indices is None: scalar = elem continue indices = tuple(sorted(indices, key=default_sort_key)) d[indices].append(scalarremove_matelement(elem, indices)) scalar = 1 return [(MatrixElement(Add.fromiter(v), k), k) for k, v in d.items()] elif isinstance(expr, KroneckerDelta): i1, i2 = expr.args if dimensions is not None: identity = Identity(dimensions[0]) else: identity = S.One return [(MatrixElement(identity, i1, i2), (i1, i2))] elif isinstance(expr, MatrixElement): matrix_symbol, i1, i2 = expr.args if i1 in index_ranges: r1, r2 = index_ranges[i1] if r1 != 0 or matrix_symbol.shape[0] != r2+1: raise ValueError("index range mismatch: {0} vs. (0, {1})".format( (r1, r2), matrix_symbol.shape[0])) if i2 in index_ranges: r1, r2 = index_ranges[i2] if r1 != 0 or matrix_symbol.shape[1] != r2+1: raise ValueError("index range mismatch: {0} vs. (0, {1})".format( (r1, r2), matrix_symbol.shape[1])) if (i1 == i2) and (i1 in index_ranges): return [(trace(matrix_symbol), None)] return [(MatrixElement(matrix_symbol, i1, i2), (i1, i2))] elif isinstance(expr, Sum): return recurse_expr( expr.args[0], index_ranges={i[0]: i[1:] for i in expr.args[1:]} ) else: return [(expr, None)] retvals = recurse_expr(expr) factors, indices = zip(retvals) retexpr = Mul.fromiter(factors) if len(indices) == 0 or list(set(indices)) == [None]: return retexpr if first_index is None: for i in indices: if i is not None: ind0 = i break return remove_matelement(retexpr, ind0) else: return remove_matelement(retexpr, first_index, last_index) def applyfunc(self, func): from .applyfunc import ElementwiseApplyFunction return ElementwiseApplyFunction(func, self) def _matrix_derivative(expr, x): from sympy import Derivative lines = expr._eval_derivative_matrix_lines(x) first = lines[0].first second = lines[0].second higher = lines[0].higher ranks = [i.rank() for i in lines] assert len(set(ranks)) == 1 rank = ranks[0] if rank <= 2: return reduce(lambda x, y: x+y, [i.matrix_form() for i in lines]) if first != 1: return reduce(lambda x,y: x+y, [lr.first lr.second.T for lr in lines]) elif higher != 1: return reduce(lambda x,y: x+y, [lr.higher for lr in lines]) return Derivative(expr, x) class MatrixElement(Expr): parent = property(lambda self: self.args[0]) i = property(lambda self: self.args[1]) j = property(lambda self: self.args[2]) _diff_wrt = True is_symbol = True is_commutative = True def __new__(cls, name, n, m): n, m = map(sympify, (n, m)) from sympy import MatrixBase if isinstance(name, (MatrixBase,)): if n.is_Integer and m.is_Integer: return name[n, m] name = sympify(name) obj = Expr.__new__(cls, name, n, m) return obj def doit(self, kwargs): deep = kwargs.get('deep', True) if deep: args = [arg.doit(kwargs) for arg in self.args] else: args = self.args return args[0][args[1], args[2]] @property def indices(self): return self.args[1:] def _eval_derivative(self, v): from sympy import Sum, symbols, Dummy if not isinstance(v, MatrixElement): from sympy import MatrixBase if isinstance(self.parent, MatrixBase): return self.parent.diff(v)[self.i, self.j] return S.Zero M = self.args[0] if M == v.args[0]: return KroneckerDelta(self.args[1], v.args[1])KroneckerDelta(self.args[2], v.args[2]) if isinstance(M, Inverse): i, j = self.args[1:] i1, i2 = symbols("z1, z2", cls=Dummy) Y = M.args[0] r1, r2 = Y.shape return -Sum(M[i, i1]Y[i1, i2].diff(v)M[i2, j], (i1, 0, r1-1), (i2, 0, r2-1)) if self.has(v.args[0]): return None return S.Zero class MatrixSymbol(MatrixExpr): """Symbolic representation of a Matrix object Creates a SymPy Symbol to represent a Matrix. This matrix has a shape and can be included in Matrix Expressions Examples ======== >>> from sympy import MatrixSymbol, Identity >>> A = MatrixSymbol('A', 3, 4) # A 3 by 4 Matrix >>> B = MatrixSymbol('B', 4, 3) # A 4 by 3 Matrix >>> A.shape (3, 4) >>> 2AB + Identity(3) I + 2AB """ is_commutative = False is_symbol = True _diff_wrt = True def __new__(cls, name, n, m): n, m = sympify(n), sympify(m) obj = Basic.__new__(cls, name, n, m) return obj def _hashable_content(self): return (self.name, self.shape) @property def shape(self): return self.args[1:3] @property def name(self): return self.args[0] def _eval_subs(self, old, new): # only do substitutions in shape shape = Tuple(self.shape)._subs(old, new) return MatrixSymbol(self.name, shape) def __call__(self, args): raise TypeError("%s object is not callable" % self.__class__) def _entry(self, i, j, kwargs): return MatrixElement(self, i, j) @property def free_symbols(self): return set((self,)) def doit(self, hints): if hints.get('deep', True): return type(self)(self.name, self.args[1].doit(hints), self.args[2].doit(hints)) else: return self def _eval_simplify(self, *kwargs): return self def _eval_derivative_matrix_lines(self, x): if self != x: return [_LeftRightArgs( ZeroMatrix(x.shape[0], self.shape[0]), ZeroMatrix(x.shape[1], self.shape[1]), transposed=False, )] else: first=Identity(self.shape[0]) second=Identity(self.shape[1]) return [_LeftRightArgs( first=first, second=second, transposed=False, )] class Identity(MatrixExpr): """The Matrix Identity I - multiplicative identity Examples ======== >>> from sympy.matrices import Identity, MatrixSymbol >>> A = MatrixSymbol('A', 3, 5) >>> I = Identity(3) >>> IA A """ is_Identity = True def __new__(cls, n): return super(Identity, cls).__new__(cls, sympify(n)) @property def rows(self): return self.args[0] @property def cols(self): return self.args[0] @property def shape(self): return (self.args[0], self.args[0]) def _eval_transpose(self): return self def _eval_trace(self): return self.rows def _eval_inverse(self): return self def conjugate(self): return self def _entry(self, i, j, *kwargs): eq = Eq(i, j) if eq is S.true: return S.One elif eq is S.false: return S.Zero return KroneckerDelta(i, j) def _eval_determinant(self): return S.One class ZeroMatrix(MatrixExpr): """The Matrix Zero 0 - additive identity Examples ======== >>> from sympy import MatrixSymbol, ZeroMatrix >>> A = MatrixSymbol('A', 3, 5) >>> Z = ZeroMatrix(3, 5) >>> A + Z A >>> ZA.T 0 """ is_ZeroMatrix = True def __new__(cls, m, n): return super(ZeroMatrix, cls).__new__(cls, m, n) @property def shape(self): return (self.args[0], self.args[1]) @_sympifyit('other', NotImplemented) @call_highest_priority('__rpow__') def __pow__(self, other): if other != 1 and not self.is_square: raise ShapeError("Power of non-square matrix %s" % self) if other == 0: return Identity(self.rows) if other < 1: raise ValueError("Matrix det == 0; not invertible.") return self def _eval_transpose(self): return ZeroMatrix(self.cols, self.rows) def _eval_trace(self): return S.Zero def _eval_determinant(self): return S.Zero def conjugate(self): return self def _entry(self, i, j, *kwargs): return S.Zero def __nonzero__(self): return False __bool__ = __nonzero__ def matrix_symbols(expr): return [sym for sym in expr.free_symbols if sym.is_Matrix] class _LeftRightArgs(object): r""" Helper class to compute matrix derivatives. The logic: when an expression is derived by a matrix `X_{mn}`, two lines of matrix multiplications are created: the one contracted to `m` (first line), and the one contracted to `n` (second line). Transposition flips the side by which new matrices are connected to the lines. The trace connects the end of the two lines. """ def __init__(self, first, second, higher=S.One, transposed=False): self.first = first self.second = second self.higher = higher self.transposed = transposed def __repr__(self): return "_LeftRightArgs(first=%s[%s], second=%s[%s], higher=%s, transposed=%s)" % ( self.first, self.first.shape if isinstance(self.first, MatrixExpr) else None, self.second, self.second.shape if isinstance(self.second, MatrixExpr) else None, self.higher, self.transposed, ) def transpose(self): self.transposed = not self.transposed return self def matrix_form(self): if self.first != 1 and self.higher != 1: raise ValueError("higher dimensional array cannot be represented") if self.first != 1: return self.firstself.second.T else: return self.higher def rank(self): """ Number of dimensions different from trivial (warning: not related to matrix rank). """ rank = 0 if self.first != 1: rank += sum([i != 1 for i in self.first.shape]) if self.second != 1: rank += sum([i != 1 for i in self.second.shape]) if self.higher != 1: rank += 2 return rank def append_first(self, other): self.first = other def append_second(self, other): self.second = other def __hash__(self): return hash((self.first, self.second, self.transposed)) def __eq__(self, other): if not isinstance(other, _LeftRightArgs): return False return (self.first == other.first) and (self.second == other.second) and (self.transposed == other.transposed) from .matmul import MatMul from .matadd import MatAdd from .matpow import MatPow from .transpose import Transpose from .inverse import Inverse
b0ec35a24973f5c27340cd80789f8ec7fb19756d8e10ff7a56e0621272d11c5d	"""Implementation of the Kronecker product""" from __future__ import division, print_function from sympy.core import Add, Mul, Pow, prod, sympify from sympy.core.compatibility import range from sympy.functions import adjoint from sympy.matrices.expressions.matexpr import MatrixExpr, ShapeError, Identity from sympy.matrices.expressions.transpose import transpose from sympy.matrices.matrices import MatrixBase from sympy.strategies import ( canon, condition, distribute, do_one, exhaust, flatten, typed, unpack) from sympy.strategies.traverse import bottom_up from sympy.utilities import sift from .matadd import MatAdd from .matmul import MatMul from .matpow import MatPow def kronecker_product(matrices): """ The Kronecker product of two or more arguments. This computes the explicit Kronecker product for subclasses of ``MatrixBase`` i.e. explicit matrices. Otherwise, a symbolic ``KroneckerProduct`` object is returned. Examples ======== For ``MatrixSymbol`` arguments a ``KroneckerProduct`` object is returned. Elements of this matrix can be obtained by indexing, or for MatrixSymbols with known dimension the explicit matrix can be obtained with ``.as_explicit()`` >>> from sympy.matrices import kronecker_product, MatrixSymbol >>> A = MatrixSymbol('A', 2, 2) >>> B = MatrixSymbol('B', 2, 2) >>> kronecker_product(A) A >>> kronecker_product(A, B) KroneckerProduct(A, B) >>> kronecker_product(A, B)[0, 1] A[0, 0]B[0, 1] >>> kronecker_product(A, B).as_explicit() Matrix([ [A[0, 0]B[0, 0], A[0, 0]B[0, 1], A[0, 1]B[0, 0], A[0, 1]B[0, 1]], [A[0, 0]B[1, 0], A[0, 0]B[1, 1], A[0, 1]B[1, 0], A[0, 1]B[1, 1]], [A[1, 0]B[0, 0], A[1, 0]B[0, 1], A[1, 1]B[0, 0], A[1, 1]B[0, 1]], [A[1, 0]B[1, 0], A[1, 0]B[1, 1], A[1, 1]B[1, 0], A[1, 1]B[1, 1]]]) For explicit matrices the Kronecker product is returned as a Matrix >>> from sympy.matrices import Matrix, kronecker_product >>> sigma_x = Matrix([ ... [0, 1], ... [1, 0]]) ... >>> Isigma_y = Matrix([ ... [0, 1], ... [-1, 0]]) ... >>> kronecker_product(sigma_x, Isigma_y) Matrix([ [ 0, 0, 0, 1], [ 0, 0, -1, 0], [ 0, 1, 0, 0], [-1, 0, 0, 0]]) See Also ======== KroneckerProduct """ if not matrices: raise TypeError("Empty Kronecker product is undefined") validate(matrices) if len(matrices) == 1: return matrices[0] else: return KroneckerProduct(matrices).doit() class KroneckerProduct(MatrixExpr): """ The Kronecker product of two or more arguments. The Kronecker product is a non-commutative product of matrices. Given two matrices of dimension (m, n) and (s, t) it produces a matrix of dimension (m s, n t). This is a symbolic object that simply stores its argument without evaluating it. To actually compute the product, use the function ``kronecker_product()`` or call the the ``.doit()`` or ``.as_explicit()`` methods. >>> from sympy.matrices import KroneckerProduct, MatrixSymbol >>> A = MatrixSymbol('A', 5, 5) >>> B = MatrixSymbol('B', 5, 5) >>> isinstance(KroneckerProduct(A, B), KroneckerProduct) True """ is_KroneckerProduct = True def __new__(cls, args, kwargs): args = list(map(sympify, args)) if all(a.is_Identity for a in args): ret = Identity(prod(a.rows for a in args)) if all(isinstance(a, MatrixBase) for a in args): return ret.as_explicit() else: return ret check = kwargs.get('check', True) if check: validate(args) return super(KroneckerProduct, cls).__new__(cls, args) @property def shape(self): rows, cols = self.args[0].shape for mat in self.args[1:]: rows = mat.rows cols = mat.cols return (rows, cols) def _entry(self, i, j): result = 1 for mat in reversed(self.args): i, m = divmod(i, mat.rows) j, n = divmod(j, mat.cols) result = mat[m, n] return result def _eval_adjoint(self): return KroneckerProduct(list(map(adjoint, self.args))).doit() def _eval_conjugate(self): return KroneckerProduct([a.conjugate() for a in self.args]).doit() def _eval_transpose(self): return KroneckerProduct(list(map(transpose, self.args))).doit() def _eval_trace(self): from .trace import trace return prod(trace(a) for a in self.args) def _eval_determinant(self): from .determinant import det, Determinant if not all(a.is_square for a in self.args): return Determinant(self) m = self.rows return prod(det(a)(m/a.rows) for a in self.args) def _eval_inverse(self): try: return KroneckerProduct([a.inverse() for a in self.args]) except ShapeError: from sympy.matrices.expressions.inverse import Inverse return Inverse(self) def structurally_equal(self, other): '''Determine whether two matrices have the same Kronecker product structure Examples ======== >>> from sympy import KroneckerProduct, MatrixSymbol, symbols >>> m, n = symbols(r'm, n', integer=True) >>> A = MatrixSymbol('A', m, m) >>> B = MatrixSymbol('B', n, n) >>> C = MatrixSymbol('C', m, m) >>> D = MatrixSymbol('D', n, n) >>> KroneckerProduct(A, B).structurally_equal(KroneckerProduct(C, D)) True >>> KroneckerProduct(A, B).structurally_equal(KroneckerProduct(D, C)) False >>> KroneckerProduct(A, B).structurally_equal(C) False ''' # Inspired by BlockMatrix return (isinstance(other, KroneckerProduct) and self.shape == other.shape and len(self.args) == len(other.args) and all(a.shape == b.shape for (a, b) in zip(self.args, other.args))) def has_matching_shape(self, other): '''Determine whether two matrices have the appropriate structure to bring matrix multiplication inside the KroneckerProdut Examples ======== >>> from sympy import KroneckerProduct, MatrixSymbol, symbols >>> m, n = symbols(r'm, n', integer=True) >>> A = MatrixSymbol('A', m, n) >>> B = MatrixSymbol('B', n, m) >>> KroneckerProduct(A, B).has_matching_shape(KroneckerProduct(B, A)) True >>> KroneckerProduct(A, B).has_matching_shape(KroneckerProduct(A, B)) False >>> KroneckerProduct(A, B).has_matching_shape(A) False ''' return (isinstance(other, KroneckerProduct) and self.cols == other.rows and len(self.args) == len(other.args) and all(a.cols == b.rows for (a, b) in zip(self.args, other.args))) def _eval_expand_kroneckerproduct(self, *hints): return flatten(canon(typed({KroneckerProduct: distribute(KroneckerProduct, MatAdd)}))(self)) def _kronecker_add(self, other): if self.structurally_equal(other): return self.__class__([a + b for (a, b) in zip(self.args, other.args)]) else: return self + other def _kronecker_mul(self, other): if self.has_matching_shape(other): return self.__class__([ab for (a, b) in zip(self.args, other.args)]) else: return self * other def doit(self, kwargs): deep = kwargs.get('deep', True) if deep: args = [arg.doit(kwargs) for arg in self.args] else: args = self.args return canonicalize(KroneckerProduct(args)) def validate(args): if not all(arg.is_Matrix for arg in args): raise TypeError("Mix of Matrix and Scalar symbols") # rules def extract_commutative(kron): c_part = [] nc_part = [] for arg in kron.args: c, nc = arg.args_cnc() c_part.extend(c) nc_part.append(Mul._from_args(nc)) c_part = Mul(c_part) if c_part != 1: return c_partKroneckerProduct(nc_part) return kron def matrix_kronecker_product(matrices): """Compute the Kronecker product of a sequence of SymPy Matrices. This is the standard Kronecker product of matrices [1]. Parameters ========== matrices : tuple of MatrixBase instances The matrices to take the Kronecker product of. Returns ======= matrix : MatrixBase The Kronecker product matrix. Examples ======== >>> from sympy import Matrix >>> from sympy.matrices.expressions.kronecker import ( ... matrix_kronecker_product) >>> m1 = Matrix([[1,2],[3,4]]) >>> m2 = Matrix([[1,0],[0,1]]) >>> matrix_kronecker_product(m1, m2) Matrix([ [1, 0, 2, 0], [0, 1, 0, 2], [3, 0, 4, 0], [0, 3, 0, 4]]) >>> matrix_kronecker_product(m2, m1) Matrix([ [1, 2, 0, 0], [3, 4, 0, 0], [0, 0, 1, 2], [0, 0, 3, 4]]) References ========== [1] https://en.wikipedia.org/wiki/Kronecker_product """ # Make sure we have a sequence of Matrices if not all(isinstance(m, MatrixBase) for m in matrices): raise TypeError( 'Sequence of Matrices expected, got: %s' % repr(matrices) ) # Pull out the first element in the product. matrix_expansion = matrices[-1] # Do the kronecker product working from right to left. for mat in reversed(matrices[:-1]): rows = mat.rows cols = mat.cols # Go through each row appending kronecker product to. # running matrix_expansion. for i in range(rows): start = matrix_expansionmat[icols] # Go through each column joining each item for j in range(cols - 1): start = start.row_join( matrix_expansionmat[icols + j + 1] ) # If this is the first element, make it the start of the # new row. if i == 0: next = start else: next = next.col_join(start) matrix_expansion = next MatrixClass = max(matrices, key=lambda M: M._class_priority).__class__ if isinstance(matrix_expansion, MatrixClass): return matrix_expansion else: return MatrixClass(matrix_expansion) def explicit_kronecker_product(kron): # Make sure we have a sequence of Matrices if not all(isinstance(m, MatrixBase) for m in kron.args): return kron return matrix_kronecker_product(kron.args) rules = (unpack, explicit_kronecker_product, flatten, extract_commutative) canonicalize = exhaust(condition(lambda x: isinstance(x, KroneckerProduct), do_one(rules))) def _kronecker_dims_key(expr): if isinstance(expr, KroneckerProduct): return tuple(a.shape for a in expr.args) else: return (0,) def kronecker_mat_add(expr): from functools import reduce args = sift(expr.args, _kronecker_dims_key) nonkrons = args.pop((0,), None) if not args: return expr krons = [reduce(lambda x, y: x._kronecker_add(y), group) for group in args.values()] if not nonkrons: return MatAdd(krons) else: return MatAdd(krons) + nonkrons def kronecker_mat_mul(expr): # modified from block matrix code factor, matrices = expr.as_coeff_matrices() i = 0 while i < len(matrices) - 1: A, B = matrices[i:i+2] if isinstance(A, KroneckerProduct) and isinstance(B, KroneckerProduct): matrices[i] = A._kronecker_mul(B) matrices.pop(i+1) else: i += 1 return factorMatMul(matrices) def kronecker_mat_pow(expr): if isinstance(expr.base, KroneckerProduct): return KroneckerProduct([MatPow(a, expr.exp) for a in expr.base.args]) else: return expr def combine_kronecker(expr): """Combine KronekeckerProduct with expression. If possible write operations on KroneckerProducts of compatible shapes as a single KroneckerProduct. Examples ======== >>> from sympy.matrices.expressions import MatrixSymbol, KroneckerProduct, combine_kronecker >>> from sympy import symbols >>> m, n = symbols(r'm, n', integer=True) >>> A = MatrixSymbol('A', m, n) >>> B = MatrixSymbol('B', n, m) >>> combine_kronecker(KroneckerProduct(A, B)KroneckerProduct(B, A)) KroneckerProduct(AB, BA) >>> combine_kronecker(KroneckerProduct(A, B)+KroneckerProduct(B.T, A.T)) KroneckerProduct(A + B.T, B + A.T) >>> combine_kronecker(KroneckerProduct(A, B)m) KroneckerProduct(Am, B**m) """ def haskron(expr): return isinstance(expr, MatrixExpr) and expr.has(KroneckerProduct) rule = exhaust( bottom_up(exhaust(condition(haskron, typed( {MatAdd: kronecker_mat_add, MatMul: kronecker_mat_mul, MatPow: kronecker_mat_pow}))))) result = rule(expr) try: return result.doit() except AttributeError: return result
efa89b95a9c4d25f54f6fd8d5b267de9f81268c98c98505f0c9971122e08d3c4	from __future__ import print_function, division from sympy import Basic, Expr, sympify, S from sympy.matrices.matrices import MatrixBase from .matexpr import ShapeError class Trace(Expr): """Matrix Trace Represents the trace of a matrix expression. Examples ======== >>> from sympy import MatrixSymbol, Trace, eye >>> A = MatrixSymbol('A', 3, 3) >>> Trace(A) Trace(A) """ is_Trace = True def __new__(cls, mat): mat = sympify(mat) if not mat.is_Matrix: raise TypeError("input to Trace, %s, is not a matrix" % str(mat)) if not mat.is_square: raise ShapeError("Trace of a non-square matrix") return Basic.__new__(cls, mat) def _eval_transpose(self): return self def _eval_derivative(self, v): from sympy.matrices.expressions.matexpr import _matrix_derivative return _matrix_derivative(self, v) def _eval_derivative_matrix_lines(self, x): r = self.args[0]._eval_derivative_matrix_lines(x) for lr in r: if lr.higher == 1: lr.higher = lr.first lr.second.T else: # This is not a matrix line: lr.higher = Trace(lr.first lr.second.T) lr.first = S.One lr.second = S.One return r @property def arg(self): return self.args[0] def doit(self, kwargs): if kwargs.get('deep', True): arg = self.arg.doit(kwargs) try: return arg._eval_trace() except (AttributeError, NotImplementedError): return Trace(arg) else: # _eval_trace would go too deep here if isinstance(self.arg, MatrixBase): return trace(self.arg) else: return Trace(self.arg) def _eval_rewrite_as_Sum(self, expr, *kwargs): from sympy import Sum, Dummy i = Dummy('i') return Sum(self.arg[i, i], (i, 0, self.arg.rows-1)).doit() def trace(expr): """Trace of a Matrix. Sum of the diagonal elements. Examples ======== >>> from sympy import trace, Symbol, MatrixSymbol, pprint, eye >>> n = Symbol('n') >>> X = MatrixSymbol('X', n, n) # A square matrix >>> trace(2X) 2*Trace(X) >>> trace(eye(3)) 3 """ return Trace(expr).doit()
098bbd383a9df25eb65ffc9e8092d8af1cd6dee9fa32ba6a545b60113b8337c4	from __future__ import print_function, division from sympy.core.compatibility import reduce from operator import add from sympy.core import Add, Basic, sympify from sympy.functions import adjoint from sympy.matrices.matrices import MatrixBase from sympy.matrices.expressions.transpose import transpose from sympy.strategies import (rm_id, unpack, flatten, sort, condition, exhaust, do_one, glom) from sympy.matrices.expressions.matexpr import MatrixExpr, ShapeError, ZeroMatrix from sympy.utilities import default_sort_key, sift from sympy.core.operations import AssocOp class MatAdd(MatrixExpr, Add): """A Sum of Matrix Expressions MatAdd inherits from and operates like SymPy Add Examples ======== >>> from sympy import MatAdd, MatrixSymbol >>> A = MatrixSymbol('A', 5, 5) >>> B = MatrixSymbol('B', 5, 5) >>> C = MatrixSymbol('C', 5, 5) >>> MatAdd(A, B, C) A + B + C """ is_MatAdd = True def __new__(cls, args, kwargs): args = list(map(sympify, args)) check = kwargs.get('check', False) obj = Basic.__new__(cls, args) if check: if all(not isinstance(i, MatrixExpr) for i in args): return Add.fromiter(args) validate(args) return obj @property def shape(self): return self.args[0].shape def _entry(self, i, j, expand=None): return Add([arg._entry(i, j) for arg in self.args]) def _eval_transpose(self): return MatAdd([transpose(arg) for arg in self.args]).doit() def _eval_adjoint(self): return MatAdd([adjoint(arg) for arg in self.args]).doit() def _eval_trace(self): from .trace import trace return Add([trace(arg) for arg in self.args]).doit() def doit(self, kwargs): deep = kwargs.get('deep', True) if deep: args = [arg.doit(kwargs) for arg in self.args] else: args = self.args return canonicalize(MatAdd(args)) def _eval_derivative_matrix_lines(self, x): add_lines = [arg._eval_derivative_matrix_lines(x) for arg in self.args] return [j for i in add_lines for j in i] def validate(args): if not all(arg.is_Matrix for arg in args): raise TypeError("Mix of Matrix and Scalar symbols") A = args[0] for B in args[1:]: if A.shape != B.shape: raise ShapeError("Matrices %s and %s are not aligned"%(A, B)) factor_of = lambda arg: arg.as_coeff_mmul()[0] matrix_of = lambda arg: unpack(arg.as_coeff_mmul()[1]) def combine(cnt, mat): if cnt == 1: return mat else: return cnt mat def merge_explicit(matadd): """ Merge explicit MatrixBase arguments Examples ======== >>> from sympy import MatrixSymbol, eye, Matrix, MatAdd, pprint >>> from sympy.matrices.expressions.matadd import merge_explicit >>> A = MatrixSymbol('A', 2, 2) >>> B = eye(2) >>> C = Matrix([[1, 2], [3, 4]]) >>> X = MatAdd(A, B, C) >>> pprint(X) [1 0] [1 2] A + [ ] + [ ] [0 1] [3 4] >>> pprint(merge_explicit(X)) [2 2] A + [ ] [3 5] """ groups = sift(matadd.args, lambda arg: isinstance(arg, MatrixBase)) if len(groups[True]) > 1: return MatAdd((groups[False] + [reduce(add, groups[True])])) else: return matadd rules = (rm_id(lambda x: x == 0 or isinstance(x, ZeroMatrix)), unpack, flatten, glom(matrix_of, factor_of, combine), merge_explicit, sort(default_sort_key)) canonicalize = exhaust(condition(lambda x: isinstance(x, MatAdd), do_one(rules)))
3852db79b25e6dd9fd319d7fddebd688816c29a8c79885f1e8e0f55067e3bd18	""" Some examples have been taken from: http://www.math.uwaterloo.ca/~hwolkowi//matrixcookbook.pdf """ from sympy import MatrixSymbol, Inverse, symbols, Determinant, Trace, Derivative from sympy import MatAdd, Identity, MatMul, ZeroMatrix k = symbols("k") X = MatrixSymbol("X", k, k) x = MatrixSymbol("x", k, 1) A = MatrixSymbol("A", k, k) B = MatrixSymbol("B", k, k) C = MatrixSymbol("C", k, k) D = MatrixSymbol("D", k, k) a = MatrixSymbol("a", k, 1) b = MatrixSymbol("b", k, 1) c = MatrixSymbol("c", k, 1) d = MatrixSymbol("d", k, 1) def test_matrix_derivative_non_matrix_result(): # This is a 4-dimensional array: assert A.diff(A) == Derivative(A, A) assert A.T.diff(A) == Derivative(A.T, A) assert (2A).diff(A) == Derivative(2A, A) assert MatAdd(A, A).diff(A) == Derivative(MatAdd(A, A), A) assert (A + B).diff(A) == Derivative(A + B, A) # TODO: `B` can be removed. def test_matrix_derivative_trivial_cases(): # Cookbook example 33: assert X.diff(A) == 0 def test_matrix_derivative_with_inverse(): # Cookbook example 61: expr = a.TInverse(X)b assert expr.diff(X) == -Inverse(X).Tab.TInverse(X).T # Cookbook example 62: expr = Determinant(Inverse(X)) # Not implemented yet: # assert expr.diff(X) == -Determinant(X.inv())(X.inv()).T # Cookbook example 63: expr = Trace(AInverse(X)B) assert expr.diff(X) == -(X*(-1)BAX(-1)).T # Cookbook example 64: expr = Trace(Inverse(X + A)) assert expr.diff(X) == -(Inverse(X + A)).T2 def test_matrix_derivative_vectors_and_scalars(): # Cookbook example 69: expr = x.Ta assert expr.diff(x) == a expr = a.Tx assert expr.diff(x) == a # Cookbook example 70: expr = a.TXb assert expr.diff(X) == ab.T # Cookbook example 71: expr = a.TX.Tb assert expr.diff(X) == ba.T # Cookbook example 72: expr = a.TXa assert expr.diff(X) == aa.T expr = a.TX.Ta assert expr.diff(X) == aa.T # Cookbook example 77: expr = b.TX.TXc assert expr.diff(X) == Xbc.T + Xcb.T # Cookbook example 78: expr = (Bx + b).TC(Dx + d) assert expr.diff(x) == B.TC(Dx + d) + D.TC.T(Bx + b) # Cookbook example 81: expr = x.TBx assert expr.diff(x) == Bx + B.Tx # Cookbook example 82: expr = b.TX.TDXc assert expr.diff(X) == D.TXbc.T + DXcb.T # Cookbook example 83: expr = (Xb + c).TD(Xb + c) assert expr.diff(X) == D(Xb + c)b.T + D.T(Xb + c)b.T def test_matrix_derivatives_of_traces(): ## First order: # Cookbook example 99: expr = Trace(X) assert expr.diff(X) == Identity(k) # Cookbook example 100: expr = Trace(XA) assert expr.diff(X) == A.T # Cookbook example 101: expr = Trace(AXB) assert expr.diff(X) == A.TB.T # Cookbook example 102: expr = Trace(AX.TB) assert expr.diff(X) == BA # Cookbook example 103: expr = Trace(X.TA) assert expr.diff(X) == A # Cookbook example 104: expr = Trace(AX.T) assert expr.diff(X) == A # Cookbook example 105: # TODO: TensorProduct is not supported #expr = Trace(TensorProduct(A, X)) #assert expr.diff(X) == Trace(A)Identity(k) ## Second order: # Cookbook example 106: expr = Trace(X2) assert expr.diff(X) == 2X.T # Cookbook example 107: expr = Trace(X*2B) # TODO: wrong result #assert expr.diff(X) == (XB + BX).T expr = Trace(MatMul(X, X, B)) assert expr.diff(X) == (XB + BX).T # Cookbook example 108: expr = Trace(X.TBX) assert expr.diff(X) == BX + B.TX # Cookbook example 109: expr = Trace(BXX.T) assert expr.diff(X) == BX + B.TX # Cookbook example 110: expr = Trace(XX.TB) assert expr.diff(X) == BX + B.TX # Cookbook example 111: expr = Trace(XBX.T) assert expr.diff(X) == XB.T + XB # Cookbook example 112: expr = Trace(BX.TX) assert expr.diff(X) == XB.T + XB # Cookbook example 113: expr = Trace(X.TXB) assert expr.diff(X) == XB.T + XB # Cookbook example 114: expr = Trace(AXBX) assert expr.diff(X) == A.TX.TB.T + B.TX.TA.T # Cookbook example 115: expr = Trace(X.TX) assert expr.diff(X) == 2X expr = Trace(XX.T) assert expr.diff(X) == 2X # Cookbook example 116: expr = Trace(B.TX.TCXB) assert expr.diff(X) == C.TXBB.T + CXBB.T # Cookbook example 117: expr = Trace(X.TBXC) assert expr.diff(X) == BXC + B.TXC.T # Cookbook example 118: expr = Trace(AXBX.TC) assert expr.diff(X) == A.TC.TXB.T + CAXB # Cookbook example 119: expr = Trace((AXB + C)(AXB + C).T) assert expr.diff(X) == 2A.T(AXB + C)B.T # Cookbook example 120: # TODO: no support for TensorProduct. # expr = Trace(TensorProduct(X, X)) # expr = Trace(X)Trace(X) # expr.diff(X) == 2Trace(X)Identity(k) # Higher Order # Cookbook example 121: expr = Trace(Xk) #assert expr.diff(X) == k(X*(k-1)).T # Cookbook example 122: expr = Trace(AX*k) #assert expr.diff(X) == # Needs indices # Cookbook example 123: expr = Trace(B.TX.TCXX.TCXB) assert expr.diff(X) == CXX.TCXBB.T + C.TXBB.TX.TC.TX + CXBB.TX.TCX + C.TXX.TC.TXBB.T # Other # Cookbook example 124: expr = Trace(AX(-1)B) assert expr.diff(X) == -Inverse(X).TA.TB.TInverse(X).T # Cookbook example 125: expr = Trace(Inverse(X.TCX)A) # Warning: result in the cookbook is equivalent if B and C are symmetric: assert expr.diff(X) == - X.inv().TA.TX.inv()C.inv().TX.inv().T - X.inv().TAX.inv()C.inv()X.inv().T # Cookbook example 126: expr = Trace((X.TCX).inv()(X.TBX)) assert expr.diff(X) == -2CX(X.TCX).inv()X.TBX(X.TCX).inv() + 2BX(X.TCX).inv() # Cookbook example 127: expr = Trace((A + X.TCX).inv()(X.TBX)) # Warning: result in the cookbook is equivalent if B and C are symmetric: assert expr.diff(X) == BXInverse(A + X.TCX) - CXInverse(A + X.TCX)X.TBXInverse(A + X.TCX) - C.TXInverse(A.T + (CX).TX)X.TB.TXInverse(A.T + (CX).TX) + B.TXInverse(A.T + (CX).TX) def test_derivatives_of_complicated_matrix_expr(): expr = a.T(AX(X.TB + XA) + B.TX.T(ab.T(XDX.T + X(X.TB + AX)DB - X.TC.TA)B + B(XD.T + BAXA.T - 3XD))B + 42XBX.TA.T(X + X.T))b result = (B(BAXA.T - 3XD + XD.T) + ab.T(X(AX + X.TB)DB + XDX.T - X.TC.TA)B)Bba.TB.T + B*2ba.TB.TX.Tab.TXD + 42AXB.TX.Tab.T + BDB3ba.TB.TX.Tab.TX + Bba.TAX + 42ab.T(X + X.T)AXB.T + ba.TXBab.TB.T*2XD.T + ba.TXBab.TB.T3D.T(B.TX + X.TA.T) + 42ba.TXBX.TA.T + 42A.T(X + X.T)ba.TXB + A.TB.T*2XBab.TB.TA + A.Tab.T(A.TX.T + B.TX) + A.TX.Tba.TXBab.TB.T*3D.T + B.TXBab.TB.TD - 3B.TXBab.TB.TD.T - C.TAB2ba.TB.TX.Tab.T + X.TA.Tab.TA.T assert expr.diff(X) == result def test_mixed_deriv_mixed_expressions(): expr = Trace(A)A # TODO: this is not yet supported: assert expr.diff(A) == Derivative(expr, A) expr = Trace(Trace(A)A) assert expr.diff(A) == (2Trace(A))*Identity(k)
50b66f6d006fd4c65900552a00eff9cf2721ba8533ddb82dc0bcb6d6ca7b7254	from sympy.matrices.expressions.applyfunc import ElementwiseApplyFunction from sympy import (Matrix, Lambda, MatrixBase, MatrixSymbol, exp, symbols, MatMul, sin) from sympy.utilities.pytest import raises from sympy.matrices.common import ShapeError X = MatrixSymbol("X", 3, 3) Y = MatrixSymbol("Y", 3, 3) k = symbols("k") Xk = MatrixSymbol("X", k, k) Xd = X.as_explicit() x, y, z, t = symbols("x y z t") def test_applyfunc_matrix(): double = Lambda(x, x2) expr = ElementwiseApplyFunction(double, Xd) assert isinstance(expr, ElementwiseApplyFunction) assert expr.doit() == Xd.applyfunc(lambda x: x2) assert expr.shape == (3, 3) expr = ElementwiseApplyFunction(double, X) assert isinstance(expr, ElementwiseApplyFunction) assert isinstance(expr.doit(), ElementwiseApplyFunction) assert expr == X.applyfunc(double) expr = ElementwiseApplyFunction(exp, XY) assert expr.expr == XY assert expr.function == exp assert expr == (XY).applyfunc(exp) assert isinstance(Xexpr, MatMul) assert (Xexpr).shape == (3, 3) Z = MatrixSymbol("Z", 2, 3) assert (Zexpr).shape == (2, 3) expr = ElementwiseApplyFunction(exp, Z.T)ElementwiseApplyFunction(exp, Z) assert expr.shape == (3, 3) expr = ElementwiseApplyFunction(exp, Z)ElementwiseApplyFunction(exp, Z.T) assert expr.shape == (2, 2) raises(ShapeError, lambda: ElementwiseApplyFunction(exp, Z)ElementwiseApplyFunction(exp, Z)) M = Matrix([[x, y], [z, t]]) expr = ElementwiseApplyFunction(sin, M) assert isinstance(expr, ElementwiseApplyFunction) assert expr.function == sin assert expr.expr == M assert expr.doit() == M.applyfunc(sin) assert expr.doit() == Matrix([[sin(x), sin(y)], [sin(z), sin(t)]]) expr = ElementwiseApplyFunction(double, Xk) assert expr.doit() == expr assert expr.subs(k, 2).shape == (2, 2) assert (exprexpr).shape == (k, k) M = MatrixSymbol("M", k, t) expr2 = M.TexprM assert isinstance(expr2, MatMul) assert expr2.args[1] == expr assert expr2.shape == (t, t) expr3 = exprM assert expr3.shape == (k, t) raises(ShapeError, lambda: Mexpr)
bb4385740fc6aa84b072e9c83a98ac60fee7adf464f3e108baab1a41dfbc385a	import warnings from sympy import (plot_implicit, cos, Symbol, symbols, Eq, sin, re, And, Or, exp, I, tan, pi) from sympy.plotting.plot import unset_show from tempfile import NamedTemporaryFile, mkdtemp from sympy.utilities.pytest import skip, warns from sympy.external import import_module from sympy.utilities.tmpfiles import TmpFileManager, cleanup_tmp_files #Set plots not to show unset_show() def tmp_file(dir=None, name=''): return NamedTemporaryFile( suffix='.png', dir=dir, delete=False).name def plot_and_save(expr, args, kwargs): name = kwargs.pop('name', '') dir = kwargs.pop('dir', None) p = plot_implicit(expr, args, kwargs) p.save(tmp_file(dir=dir, name=name)) # Close the plot to avoid a warning from matplotlib p._backend.close() def plot_implicit_tests(name): temp_dir = mkdtemp() TmpFileManager.tmp_folder(temp_dir) x = Symbol('x') y = Symbol('y') z = Symbol('z') #implicit plot tests plot_and_save(Eq(y, cos(x)), (x, -5, 5), (y, -2, 2), name=name, dir=temp_dir) plot_and_save(Eq(y2, x*3 - x), (x, -5, 5), (y, -4, 4), name=name, dir=temp_dir) plot_and_save(y > 1 / x, (x, -5, 5), (y, -2, 2), name=name, dir=temp_dir) plot_and_save(y < 1 / tan(x), (x, -5, 5), (y, -2, 2), name=name, dir=temp_dir) plot_and_save(y >= 2 sin(x) * cos(x), (x, -5, 5), (y, -2, 2), name=name, dir=temp_dir) plot_and_save(y <= x2, (x, -3, 3), (y, -1, 5), name=name, dir=temp_dir) #Test all input args for plot_implicit plot_and_save(Eq(y2, x3 - x), dir=temp_dir) plot_and_save(Eq(y2, x3 - x), adaptive=False, dir=temp_dir) plot_and_save(Eq(y2, x3 - x), adaptive=False, points=500, dir=temp_dir) plot_and_save(y > x, (x, -5, 5), dir=temp_dir) plot_and_save(And(y > exp(x), y > x + 2), dir=temp_dir) plot_and_save(Or(y > x, y > -x), dir=temp_dir) plot_and_save(x2 - 1, (x, -5, 5), dir=temp_dir) plot_and_save(x*2 - 1, dir=temp_dir) plot_and_save(y > x, depth=-5, dir=temp_dir) plot_and_save(y > x, depth=5, dir=temp_dir) plot_and_save(y > cos(x), adaptive=False, dir=temp_dir) plot_and_save(y < cos(x), adaptive=False, dir=temp_dir) plot_and_save(And(y > cos(x), Or(y > x, Eq(y, x))), dir=temp_dir) plot_and_save(y - cos(pi / x), dir=temp_dir) #Test plots which cannot be rendered using the adaptive algorithm with warns(UserWarning, match="Adaptive meshing could not be applied"): plot_and_save(Eq(y, re(cos(x) + Isin(x))), name=name, dir=temp_dir) plot_and_save(x2 - 1, title='An implicit plot', dir=temp_dir) def test_line_color(): x, y = symbols('x, y') p = plot_implicit(x2 + y2 - 1, line_color="green", show=False) assert p._series[0].line_color == "green" p = plot_implicit(x2 + y**2 - 1, line_color='r', show=False) assert p._series[0].line_color == "r" def test_matplotlib(): matplotlib = import_module('matplotlib', min_module_version='1.1.0', catch=(RuntimeError,)) if matplotlib: try: plot_implicit_tests('test') test_line_color() finally: TmpFileManager.cleanup() else: skip("Matplotlib not the default backend")
1400a85b3488caad14a7dcf635e6a2e18e9ce139518b74e07007ce4f508b76a7	""" SymPy is a Python library for symbolic mathematics. It aims to become a full-featured computer algebra system (CAS) while keeping the code as simple as possible in order to be comprehensible and easily extensible. SymPy is written entirely in Python. It depends on mpmath, and other external libraries may be optionally for things like plotting support. See the webpage for more information and documentation: https://sympy.org """ from __future__ import absolute_import, print_function del absolute_import, print_function try: import mpmath except ImportError: raise ImportError("SymPy now depends on mpmath as an external library. " "See https://docs.sympy.org/latest/install.html#mpmath for more information.") del mpmath from sympy.release import __version__ if 'dev' in __version__: def enable_warnings(): import warnings warnings.filterwarnings('default', '.', DeprecationWarning, module='sympy.') del warnings enable_warnings() del enable_warnings import sys if ((sys.version_info[0] == 2 and sys.version_info[1] < 7) or (sys.version_info[0] == 3 and sys.version_info[1] < 4)): raise ImportError("Python version 2.7 or 3.4 or above " "is required for SymPy.") del sys def __sympy_debug(): # helper function so we don't import os globally import os debug_str = os.getenv('SYMPY_DEBUG', 'False') if debug_str in ('True', 'False'): return eval(debug_str) else: raise RuntimeError("unrecognized value for SYMPY_DEBUG: %s" % debug_str) SYMPY_DEBUG = __sympy_debug() from .core import * from .logic import * from .assumptions import * from .polys import * from .series import * from .functions import * from .ntheory import * from .concrete import * from .discrete import * from .simplify import * from .sets import * from .solvers import * from .matrices import * from .geometry import * from .utilities import * from .integrals import * from .tensor import * from .parsing import * from .calculus import * from .algebras import * # This module causes conflicts with other modules: # from .stats import * # Adds about .04-.05 seconds of import time # from combinatorics import * # This module is slow to import: #from physics import units from .plotting import plot, textplot, plot_backends, plot_implicit from .printing import * from .interactive import init_session, init_printing evalf._create_evalf_table() # This is slow to import: #import abc from .deprecated import *
bc17eb214da188a1feaabd712d8b6fb525b64aad33fa4483ecbe8a3f3a419372	""" Extract reference documentation from the NumPy source tree. """ from __future__ import division, absolute_import, print_function import inspect import textwrap import re import pydoc try: from collections.abc import Mapping except ImportError: # Python 2 from collections import Mapping import sys class Reader(object): """ A line-based string reader. """ def __init__(self, data): """ Parameters ---------- data : str String with lines separated by '\n'. """ if isinstance(data, list): self._str = data else: self._str = data.split('\n') # store string as list of lines self.reset() def __getitem__(self, n): return self._str[n] def reset(self): self._l = 0 # current line nr def read(self): if not self.eof(): out = self[self._l] self._l += 1 return out else: return '' def seek_next_non_empty_line(self): for l in self[self._l:]: if l.strip(): break else: self._l += 1 def eof(self): return self._l >= len(self._str) def read_to_condition(self, condition_func): start = self._l for line in self[start:]: if condition_func(line): return self[start:self._l] self._l += 1 if self.eof(): return self[start:self._l + 1] return [] def read_to_next_empty_line(self): self.seek_next_non_empty_line() def is_empty(line): return not line.strip() return self.read_to_condition(is_empty) def read_to_next_unindented_line(self): def is_unindented(line): return (line.strip() and (len(line.lstrip()) == len(line))) return self.read_to_condition(is_unindented) def peek(self, n=0): if self._l + n < len(self._str): return self[self._l + n] else: return '' def is_empty(self): return not ''.join(self._str).strip() class NumpyDocString(Mapping): def __init__(self, docstring, config={}): docstring = textwrap.dedent(docstring).split('\n') self._doc = Reader(docstring) self._parsed_data = { 'Signature': '', 'Summary': [''], 'Extended Summary': [], 'Parameters': [], 'Returns': [], 'Yields': [], 'Raises': [], 'Warns': [], 'Other Parameters': [], 'Attributes': [], 'Methods': [], 'See Also': [], # 'Notes': [], 'Warnings': [], 'References': '', # 'Examples': '', 'index': {} } self._other_keys = [] self._parse() def __getitem__(self, key): return self._parsed_data[key] def __setitem__(self, key, val): if key not in self._parsed_data: self._other_keys.append(key) self._parsed_data[key] = val def __iter__(self): return iter(self._parsed_data) def __len__(self): return len(self._parsed_data) def _is_at_section(self): self._doc.seek_next_non_empty_line() if self._doc.eof(): return False l1 = self._doc.peek().strip() # e.g. Parameters if l1.startswith('.. index::'): return True l2 = self._doc.peek(1).strip() # ---------- or ========== return l2.startswith('-'len(l1)) or l2.startswith('='len(l1)) def _strip(self, doc): i = 0 j = 0 for i, line in enumerate(doc): if line.strip(): break for j, line in enumerate(doc[::-1]): if line.strip(): break return doc[i:len(doc) - j] def _read_to_next_section(self): section = self._doc.read_to_next_empty_line() while not self._is_at_section() and not self._doc.eof(): if not self._doc.peek(-1).strip(): # previous line was empty section += [''] section += self._doc.read_to_next_empty_line() return section def _read_sections(self): while not self._doc.eof(): data = self._read_to_next_section() name = data[0].strip() if name.startswith('..'): # index section yield name, data[1:] elif len(data) < 2: yield StopIteration else: yield name, self._strip(data[2:]) def _parse_param_list(self, content): r = Reader(content) params = [] while not r.eof(): header = r.read().strip() if ' : ' in header: arg_name, arg_type = header.split(' : ')[:2] else: arg_name, arg_type = header, '' desc = r.read_to_next_unindented_line() desc = dedent_lines(desc) params.append((arg_name, arg_type, desc)) return params _name_rgx = re.compile(r"^\s(:(?P<role>\w+):`(?P<name>[a-zA-Z0-9_.-]+)`\|" r" (?P<name2>[a-zA-Z0-9_.-]+))\s", re.X) def _parse_see_also(self, content): """ func_name : Descriptive text continued text another_func_name : Descriptive text func_name1, func_name2, :meth:`func_name`, func_name3 """ items = [] def parse_item_name(text): """Match ':role:`name`' or 'name'""" m = self._name_rgx.match(text) if m: g = m.groups() if g[1] is None: return g[3], None else: return g[2], g[1] raise ValueError("%s is not an item name" % text) def push_item(name, rest): if not name: return name, role = parse_item_name(name) items.append((name, list(rest), role)) del rest[:] current_func = None rest = [] for line in content: if not line.strip(): continue m = self._name_rgx.match(line) if m and line[m.end():].strip().startswith(':'): push_item(current_func, rest) current_func, line = line[:m.end()], line[m.end():] rest = [line.split(':', 1)[1].strip()] if not rest[0]: rest = [] elif not line.startswith(' '): push_item(current_func, rest) current_func = None if ',' in line: for func in line.split(','): if func.strip(): push_item(func, []) elif line.strip(): current_func = line elif current_func is not None: rest.append(line.strip()) push_item(current_func, rest) return items def _parse_index(self, section, content): """ .. index: default :refguide: something, else, and more """ def strip_each_in(lst): return [s.strip() for s in lst] out = {} section = section.split('::') if len(section) > 1: out['default'] = strip_each_in(section[1].split(','))[0] for line in content: line = line.split(':') if len(line) > 2: out[line[1]] = strip_each_in(line[2].split(',')) return out def _parse_summary(self): """Grab signature (if given) and summary""" if self._is_at_section(): return # If several signatures present, take the last one while True: summary = self._doc.read_to_next_empty_line() summary_str = " ".join([s.strip() for s in summary]).strip() if re.compile('^([\w., ]+=)?\s[\w\.]+\(.\)$').match(summary_str): self['Signature'] = summary_str if not self._is_at_section(): continue break if summary is not None: self['Summary'] = summary if not self._is_at_section(): self['Extended Summary'] = self._read_to_next_section() def _parse(self): self._doc.reset() self._parse_summary() sections = list(self._read_sections()) section_names = set([section for section, content in sections]) has_returns = 'Returns' in section_names has_yields = 'Yields' in section_names # We could do more tests, but we are not. Arbitrarily. if has_returns and has_yields: msg = 'Docstring contains both a Returns and Yields section.' raise ValueError(msg) for (section, content) in sections: if not section.startswith('..'): section = (s.capitalize() for s in section.split(' ')) section = ' '.join(section) if section in ('Parameters', 'Returns', 'Yields', 'Raises', 'Warns', 'Other Parameters', 'Attributes', 'Methods'): self[section] = self._parse_param_list(content) elif section.startswith('.. index::'): self['index'] = self._parse_index(section, content) elif section == 'See Also': self['See Also'] = self._parse_see_also(content) else: self[section] = content # string conversion routines def _str_header(self, name, symbol='-'): return [name, len(name)symbol] def _str_indent(self, doc, indent=4): out = [] for line in doc: out += [' 'indent + line] return out def _str_signature(self): if self['Signature']: return [self['Signature'].replace('', '\')] + [''] else: return [''] def _str_summary(self): if self['Summary']: return self['Summary'] + [''] else: return [] def _str_extended_summary(self): if self['Extended Summary']: return self['Extended Summary'] + [''] else: return [] def _str_param_list(self, name): out = [] if self[name]: out += self._str_header(name) for param, param_type, desc in self[name]: if param_type: out += ['%s : %s' % (param, param_type)] else: out += [param] out += self._str_indent(desc) out += [''] return out def _str_section(self, name): out = [] if self[name]: out += self._str_header(name) out += self[name] out += [''] return out def _str_see_also(self, func_role): if not self['See Also']: return [] out = [] out += self._str_header("See Also") last_had_desc = True for func, desc, role in self['See Also']: if role: link = ':%s:`%s`' % (role, func) elif func_role: link = ':%s:`%s`' % (func_role, func) else: link = "`%s`_" % func if desc or last_had_desc: out += [''] out += [link] else: out[-1] += ", %s" % link if desc: out += self._str_indent([' '.join(desc)]) last_had_desc = True else: last_had_desc = False out += [''] return out def _str_index(self): idx = self['index'] out = [] out += ['.. index:: %s' % idx.get('default', '')] for section, references in idx.items(): if section == 'default': continue out += [' :%s: %s' % (section, ', '.join(references))] return out def __str__(self, func_role=''): out = [] out += self._str_signature() out += self._str_summary() out += self._str_extended_summary() for param_list in ('Parameters', 'Returns', 'Yields', 'Other Parameters', 'Raises', 'Warns'): out += self._str_param_list(param_list) out += self._str_section('Warnings') out += self._str_see_also(func_role) for s in ('Notes', 'References', 'Examples'): out += self._str_section(s) for param_list in ('Attributes', 'Methods'): out += self._str_param_list(param_list) out += self._str_index() return '\n'.join(out) def indent(str, indent=4): indent_str = ' 'indent if str is None: return indent_str lines = str.split('\n') return '\n'.join(indent_str + l for l in lines) def dedent_lines(lines): """Deindent a list of lines maximally""" return textwrap.dedent("\n".join(lines)).split("\n") def header(text, style='-'): return text + '\n' + stylelen(text) + '\n' class FunctionDoc(NumpyDocString): def __init__(self, func, role='func', doc=None, config={}): self._f = func self._role = role # e.g. "func" or "meth" if doc is None: if func is None: raise ValueError("No function or docstring given") doc = inspect.getdoc(func) or '' NumpyDocString.__init__(self, doc) if not self['Signature'] and func is not None: func, func_name = self.get_func() try: # try to read signature if sys.version_info[0] >= 3: argspec = inspect.getfullargspec(func) else: argspec = inspect.getargspec(func) argspec = inspect.formatargspec(argspec) argspec = argspec.replace('', '\') signature = '%s%s' % (func_name, argspec) except TypeError as e: signature = '%s()' % func_name self['Signature'] = signature def get_func(self): func_name = getattr(self._f, '__name__', self.__class__.__name__) if inspect.isclass(self._f): func = getattr(self._f, '__call__', self._f.__init__) else: func = self._f return func, func_name def __str__(self): out = '' func, func_name = self.get_func() signature = self['Signature'].replace('', '\*') roles = {'func': 'function', 'meth': 'method'} if self._role: if self._role not in roles: print("Warning: invalid role %s" % self._role) out += '.. %s:: %s\n \n\n' % (roles.get(self._role, ''), func_name) out += super(FunctionDoc, self).__str__(func_role=self._role) return out class ClassDoc(NumpyDocString): extra_public_methods = ['__call__'] def __init__(self, cls, doc=None, modulename='', func_doc=FunctionDoc, config={}): if not inspect.isclass(cls) and cls is not None: raise ValueError("Expected a class or None, but got %r" % cls) self._cls = cls self.show_inherited_members = config.get( 'show_inherited_class_members', True) if modulename and not modulename.endswith('.'): modulename += '.' self._mod = modulename if doc is None: if cls is None: raise ValueError("No class or documentation string given") doc = pydoc.getdoc(cls) NumpyDocString.__init__(self, doc) if config.get('show_class_members', True): def splitlines_x(s): if not s: return [] else: return s.splitlines() for field, items in [('Methods', self.methods), ('Attributes', self.properties)]: if not self[field]: doc_list = [] for name in sorted(items): try: doc_item = pydoc.getdoc(getattr(self._cls, name)) doc_list.append((name, '', splitlines_x(doc_item))) except AttributeError: pass # method doesn't exist self[field] = doc_list @property def methods(self): if self._cls is None: return [] return [name for name, func in inspect_getmembers(self._cls) if ((not name.startswith('_') or name in self.extra_public_methods) and callable(func))] @property def properties(self): if self._cls is None: return [] return [name for name, func in inspect_getmembers(self._cls) if not name.startswith('_') and func is None] # This function was taken verbatim from Python 2.7 inspect.getmembers() from # the standard library. The difference from Python < 2.7 is that there is the # try/except AttributeError clause added, which catches exceptions like this # one: https://gist.github.com/1471949 def inspect_getmembers(object, predicate=None): """ Return all members of an object as (name, value) pairs sorted by name. Optionally, only return members that satisfy a given predicate. """ results = [] for key in dir(object): try: value = getattr(object, key) except AttributeError: continue if not predicate or predicate(value): results.append((key, value)) results.sort() return results def _is_show_member(self, name): if self.show_inherited_members: return True # show all class members if name not in self._cls.__dict__: return False # class member is inherited, we do not show it return True
33b1547d5da85e85a3f8d7f33e136aaa459764ee64967b8ef7865627ef213cb6	from __future__ import division, absolute_import, print_function import sys import re import inspect import textwrap import pydoc import sphinx import collections from docscrape import NumpyDocString, FunctionDoc, ClassDoc if sys.version_info[0] >= 3: sixu = lambda s: s else: sixu = lambda s: unicode(s, 'unicode_escape') class SphinxDocString(NumpyDocString): def __init__(self, docstring, config={}): NumpyDocString.__init__(self, docstring, config=config) self.load_config(config) def load_config(self, config): self.use_plots = config.get('use_plots', False) self.class_members_toctree = config.get('class_members_toctree', True) # string conversion routines def _str_header(self, name, symbol='`'): return ['.. rubric:: ' + name, ''] def _str_field_list(self, name): return [':' + name + ':'] def _str_indent(self, doc, indent=4): out = [] for line in doc: out += [' 'indent + line] return out def _str_signature(self): return [''] if self['Signature']: return ['``%s``' % self['Signature']] + [''] else: return [''] def _str_summary(self): return self['Summary'] + [''] def _str_extended_summary(self): return self['Extended Summary'] + [''] def _str_returns(self, name='Returns'): out = [] if self[name]: out += self._str_field_list(name) out += [''] for param, param_type, desc in self[name]: if param_type: out += self._str_indent(['%s* : %s' % (param.strip(), param_type)]) else: out += self._str_indent([param.strip()]) if desc: out += [''] out += self._str_indent(desc, 8) out += [''] return out def _str_param_list(self, name): out = [] if self[name]: out += self._str_field_list(name) out += [''] for param, param_type, desc in self[name]: if param_type: out += self._str_indent(['%s : %s' % (param.strip(), param_type)]) else: out += self._str_indent(['%s' % param.strip()]) if desc: out += [''] out += self._str_indent(desc, 8) out += [''] return out @property def _obj(self): if hasattr(self, '_cls'): return self._cls elif hasattr(self, '_f'): return self._f return None def _str_member_list(self, name): """ Generate a member listing, autosummary:: table where possible, and a table where not. """ out = [] if self[name]: out += ['.. rubric:: %s' % name, ''] prefix = getattr(self, '_name', '') if prefix: prefix = '~%s.' % prefix # Lines that are commented out are used to make the # autosummary:: table. Since SymPy does not use the # autosummary:: functionality, it is easiest to just comment it # out. # autosum = [] others = [] for param, param_type, desc in self[name]: param = param.strip() # Check if the referenced member can have a docstring or not param_obj = getattr(self._obj, param, None) if not (callable(param_obj) or isinstance(param_obj, property) or inspect.isgetsetdescriptor(param_obj)): param_obj = None # if param_obj and (pydoc.getdoc(param_obj) or not desc): # # Referenced object has a docstring # autosum += [" %s%s" % (prefix, param)] # else: others.append((param, param_type, desc)) # if autosum: # out += ['.. autosummary::'] # if self.class_members_toctree: # out += [' :toctree:'] # out += [''] + autosum if others: maxlen_0 = max(3, max([len(x[0]) for x in others])) hdr = sixu("=")maxlen_0 + sixu(" ") + sixu("=")10 fmt = sixu('%%%ds %%s ') % (maxlen_0,) out += ['', '', hdr] for param, param_type, desc in others: desc = sixu(" ").join(x.strip() for x in desc).strip() if param_type: desc = "(%s) %s" % (param_type, desc) out += [fmt % (param.strip(), desc)] out += [hdr] out += [''] return out def _str_section(self, name): out = [] if self[name]: out += self._str_header(name) out += [''] content = textwrap.dedent("\n".join(self[name])).split("\n") out += content out += [''] return out def _str_see_also(self, func_role): out = [] if self['See Also']: see_also = super(SphinxDocString, self)._str_see_also(func_role) out = ['.. seealso::', ''] out += self._str_indent(see_also[2:]) return out def _str_warnings(self): out = [] if self['Warnings']: out = ['.. warning::', ''] out += self._str_indent(self['Warnings']) return out def _str_index(self): idx = self['index'] out = [] if len(idx) == 0: return out out += ['.. index:: %s' % idx.get('default', '')] for section, references in idx.items(): if section == 'default': continue elif section == 'refguide': out += [' single: %s' % (', '.join(references))] else: out += [' %s: %s' % (section, ','.join(references))] return out def _str_references(self): out = [] if self['References']: out += self._str_header('References') if isinstance(self['References'], str): self['References'] = [self['References']] out.extend(self['References']) out += [''] # Latex collects all references to a separate bibliography, # so we need to insert links to it if sphinx.__version__ >= "0.6": out += ['.. only:: latex', ''] else: out += ['.. latexonly::', ''] items = [] for line in self['References']: m = re.match(r'.. \[([a-z0-9._-]+)\]', line, re.I) if m: items.append(m.group(1)) out += [' ' + ", ".join(["[%s]_" % item for item in items]), ''] return out def _str_examples(self): examples_str = "\n".join(self['Examples']) if (self.use_plots and 'import matplotlib' in examples_str and 'plot::' not in examples_str): out = [] out += self._str_header('Examples') out += ['.. plot::', ''] out += self._str_indent(self['Examples']) out += [''] return out else: return self._str_section('Examples') def __str__(self, indent=0, func_role="obj"): out = [] out += self._str_signature() out += self._str_index() + [''] out += self._str_summary() out += self._str_extended_summary() out += self._str_param_list('Parameters') out += self._str_returns('Returns') out += self._str_returns('Yields') for param_list in ('Other Parameters', 'Raises', 'Warns'): out += self._str_param_list(param_list) out += self._str_warnings() for s in self._other_keys: out += self._str_section(s) out += self._str_see_also(func_role) out += self._str_references() out += self._str_member_list('Attributes') out = self._str_indent(out, indent) return '\n'.join(out) class SphinxFunctionDoc(SphinxDocString, FunctionDoc): def __init__(self, obj, doc=None, config={}): self.load_config(config) FunctionDoc.__init__(self, obj, doc=doc, config=config) class SphinxClassDoc(SphinxDocString, ClassDoc): def __init__(self, obj, doc=None, func_doc=None, config={}): self.load_config(config) ClassDoc.__init__(self, obj, doc=doc, func_doc=None, config=config) class SphinxObjDoc(SphinxDocString): def __init__(self, obj, doc=None, config={}): self._f = obj self.load_config(config) SphinxDocString.__init__(self, doc, config=config) def get_doc_object(obj, what=None, doc=None, config={}): if inspect.isclass(obj): what = 'class' elif inspect.ismodule(obj): what = 'module' elif callable(obj): what = 'function' else: what = 'object' if what == 'class': return SphinxClassDoc(obj, func_doc=SphinxFunctionDoc, doc=doc, config=config) elif what in ('function', 'method'): return SphinxFunctionDoc(obj, doc=doc, config=config) else: if doc is None: doc = pydoc.getdoc(obj) return SphinxObjDoc(obj, doc, config=config)
3af3e32a847c46a7d6a71376c9059a3dedf7522b64733ed31c7a17ed96369c62	""" Continuous Random Variables - Prebuilt variables Contains ======== Arcsin Benini Beta BetaPrime Cauchy Chi ChiNoncentral ChiSquared Dagum Erlang Exponential FDistribution FisherZ Frechet Gamma GammaInverse Gumbel Gompertz Kumaraswamy Laplace Logistic LogNormal Maxwell Nakagami Normal Pareto QuadraticU RaisedCosine Rayleigh ShiftedGompertz StudentT Trapezoidal Triangular Uniform UniformSum VonMises Weibull WignerSemicircle """ from __future__ import print_function, division from sympy import (log, sqrt, pi, S, Dummy, Interval, sympify, gamma, Piecewise, And, Eq, binomial, factorial, Sum, floor, Abs, Lambda, Basic, lowergamma, erf, erfi, I, hyper, uppergamma, sinh, Ne, expint) from sympy import beta as beta_fn from sympy import cos, sin, exp, besseli, besselj, besselk from sympy.stats.crv import (SingleContinuousPSpace, SingleContinuousDistribution, ContinuousDistributionHandmade) from sympy.stats.rv import _value_check, RandomSymbol from sympy.matrices import MatrixBase from sympy.stats.joint_rv_types import multivariate_rv from sympy.stats.joint_rv import MarginalDistribution, JointPSpace, CompoundDistribution from sympy.external import import_module import random oo = S.Infinity __all__ = ['ContinuousRV', 'Arcsin', 'Benini', 'Beta', 'BetaPrime', 'Cauchy', 'Chi', 'ChiNoncentral', 'ChiSquared', 'Dagum', 'Erlang', 'Exponential', 'FDistribution', 'FisherZ', 'Frechet', 'Gamma', 'GammaInverse', 'Gompertz', 'Gumbel', 'Kumaraswamy', 'Laplace', 'Logistic', 'LogNormal', 'Maxwell', 'Nakagami', 'Normal', 'Pareto', 'QuadraticU', 'RaisedCosine', 'Rayleigh', 'StudentT', 'ShiftedGompertz', 'Trapezoidal', 'Triangular', 'Uniform', 'UniformSum', 'VonMises', 'Weibull', 'WignerSemicircle' ] def ContinuousRV(symbol, density, set=Interval(-oo, oo)): """ Create a Continuous Random Variable given the following: -- a symbol -- a probability density function -- set on which the pdf is valid (defaults to entire real line) Returns a RandomSymbol. Many common continuous random variable types are already implemented. This function should be necessary only very rarely. Examples ======== >>> from sympy import Symbol, sqrt, exp, pi >>> from sympy.stats import ContinuousRV, P, E >>> x = Symbol("x") >>> pdf = sqrt(2)exp(-x2/2)/(2sqrt(pi)) # Normal distribution >>> X = ContinuousRV(x, pdf) >>> E(X) 0 >>> P(X>0) 1/2 """ pdf = Piecewise((density, set.as_relational(symbol)), (0, True)) pdf = Lambda(symbol, pdf) dist = ContinuousDistributionHandmade(pdf, set) return SingleContinuousPSpace(symbol, dist).value def rv(symbol, cls, args): args = list(map(sympify, args)) dist = cls(args) dist.check(args) pspace = SingleContinuousPSpace(symbol, dist) if any(isinstance(arg, RandomSymbol) for arg in args): pspace = JointPSpace(symbol, CompoundDistribution(dist)) return pspace.value ######################################## # Continuous Probability Distributions # ######################################## #------------------------------------------------------------------------------- # Arcsin distribution ---------------------------------------------------------- class ArcsinDistribution(SingleContinuousDistribution): _argnames = ('a', 'b') def pdf(self, x): return 1/(pisqrt((x - self.a)(self.b - x))) def _cdf(self, x): from sympy import asin a, b = self.a, self.b return Piecewise( (S.Zero, x < a), (2asin(sqrt((x - a)/(b - a)))/pi, x <= b), (S.One, True)) def Arcsin(name, a=0, b=1): r""" Create a Continuous Random Variable with an arcsin distribution. The density of the arcsin distribution is given by .. math:: f(x) := \frac{1}{\pi\sqrt{(x-a)(b-x)}} with :math:`x \in [a,b]`. It must hold that :math:`-\infty < a < b < \infty`. Parameters ========== a : Real number, the left interval boundary b : Real number, the right interval boundary Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Arcsin, density, cdf >>> from sympy import Symbol, simplify >>> a = Symbol("a", real=True) >>> b = Symbol("b", real=True) >>> z = Symbol("z") >>> X = Arcsin("x", a, b) >>> density(X)(z) 1/(pisqrt((-a + z)(b - z))) >>> cdf(X)(z) Piecewise((0, a > z), (2asin(sqrt((-a + z)/(-a + b)))/pi, b >= z), (1, True)) References ========== .. [1] https://en.wikipedia.org/wiki/Arcsine_distribution """ return rv(name, ArcsinDistribution, (a, b)) #------------------------------------------------------------------------------- # Benini distribution ---------------------------------------------------------- class BeniniDistribution(SingleContinuousDistribution): _argnames = ('alpha', 'beta', 'sigma') @property def set(self): return Interval(self.sigma, oo) def pdf(self, x): alpha, beta, sigma = self.alpha, self.beta, self.sigma return (exp(-alphalog(x/sigma) - betalog(x/sigma)*2) (alpha/x + 2betalog(x/sigma)/x)) def _moment_generating_function(self, t): raise NotImplementedError('The moment generating function of the ' 'Benini distribution does not exist.') def Benini(name, alpha, beta, sigma): r""" Create a Continuous Random Variable with a Benini distribution. The density of the Benini distribution is given by .. math:: f(x) := e^{-\alpha\log{\frac{x}{\sigma}} -\beta\log^2\left[{\frac{x}{\sigma}}\right]} \left(\frac{\alpha}{x}+\frac{2\beta\log{\frac{x}{\sigma}}}{x}\right) This is a heavy-tailed distrubtion and is also known as the log-Rayleigh distribution. Parameters ========== alpha : Real number, `\alpha > 0`, a shape beta : Real number, `\beta > 0`, a shape sigma : Real number, `\sigma > 0`, a scale Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Benini, density >>> from sympy import Symbol, simplify, pprint >>> alpha = Symbol("alpha", positive=True) >>> beta = Symbol("beta", positive=True) >>> sigma = Symbol("sigma", positive=True) >>> z = Symbol("z") >>> X = Benini("x", alpha, beta, sigma) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) / / z \\ / z \ 2/ z \ \| 2betalog\|-----\|\| - alphalog\|-----\| - betalog \|-----\| \|alpha \sigma/\| \sigma/ \sigma/ \|----- + -----------------\|e \ z z / References ========== .. [1] https://en.wikipedia.org/wiki/Benini_distribution .. [2] http://reference.wolfram.com/legacy/v8/ref/BeniniDistribution.html """ return rv(name, BeniniDistribution, (alpha, beta, sigma)) #------------------------------------------------------------------------------- # Beta distribution ------------------------------------------------------------ class BetaDistribution(SingleContinuousDistribution): _argnames = ('alpha', 'beta') set = Interval(0, 1) @staticmethod def check(alpha, beta): _value_check(alpha > 0, "Alpha must be positive") _value_check(beta > 0, "Beta must be positive") def pdf(self, x): alpha, beta = self.alpha, self.beta return x(alpha - 1) (1 - x)*(beta - 1) / beta_fn(alpha, beta) def sample(self): return random.betavariate(self.alpha, self.beta) def _characteristic_function(self, t): return hyper((self.alpha,), (self.alpha + self.beta,), It) def _moment_generating_function(self, t): return hyper((self.alpha,), (self.alpha + self.beta,), t) def Beta(name, alpha, beta): r""" Create a Continuous Random Variable with a Beta distribution. The density of the Beta distribution is given by .. math:: f(x) := \frac{x^{\alpha-1}(1-x)^{\beta-1}} {\mathrm{B}(\alpha,\beta)} with :math:`x \in [0,1]`. Parameters ========== alpha : Real number, `\alpha > 0`, a shape beta : Real number, `\beta > 0`, a shape Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Beta, density, E, variance >>> from sympy import Symbol, simplify, pprint, expand_func >>> alpha = Symbol("alpha", positive=True) >>> beta = Symbol("beta", positive=True) >>> z = Symbol("z") >>> X = Beta("x", alpha, beta) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) alpha - 1 beta - 1 z (-z + 1) --------------------------- B(alpha, beta) >>> expand_func(simplify(E(X, meijerg=True))) alpha/(alpha + beta) >>> simplify(variance(X, meijerg=True)) #doctest: +SKIP alphabeta/((alpha + beta)*2(alpha + beta + 1)) References ========== .. [1] https://en.wikipedia.org/wiki/Beta_distribution .. [2] http://mathworld.wolfram.com/BetaDistribution.html """ return rv(name, BetaDistribution, (alpha, beta)) #------------------------------------------------------------------------------- # Beta prime distribution ------------------------------------------------------ class BetaPrimeDistribution(SingleContinuousDistribution): _argnames = ('alpha', 'beta') set = Interval(0, oo) def pdf(self, x): alpha, beta = self.alpha, self.beta return x*(alpha - 1)(1 + x)*(-alpha - beta)/beta_fn(alpha, beta) def BetaPrime(name, alpha, beta): r""" Create a continuous random variable with a Beta prime distribution. The density of the Beta prime distribution is given by .. math:: f(x) := \frac{x^{\alpha-1} (1+x)^{-\alpha -\beta}}{B(\alpha,\beta)} with :math:`x > 0`. Parameters ========== alpha : Real number, `\alpha > 0`, a shape beta : Real number, `\beta > 0`, a shape Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import BetaPrime, density >>> from sympy import Symbol, pprint >>> alpha = Symbol("alpha", positive=True) >>> beta = Symbol("beta", positive=True) >>> z = Symbol("z") >>> X = BetaPrime("x", alpha, beta) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) alpha - 1 -alpha - beta z (z + 1) ------------------------------- B(alpha, beta) References ========== .. [1] https://en.wikipedia.org/wiki/Beta_prime_distribution .. [2] http://mathworld.wolfram.com/BetaPrimeDistribution.html """ return rv(name, BetaPrimeDistribution, (alpha, beta)) #------------------------------------------------------------------------------- # Cauchy distribution ---------------------------------------------------------- class CauchyDistribution(SingleContinuousDistribution): _argnames = ('x0', 'gamma') def pdf(self, x): return 1/(piself.gamma(1 + ((x - self.x0)/self.gamma)*2)) def _characteristic_function(self, t): return exp(self.x0 I * t - self.gamma * Abs(t)) def _moment_generating_function(self, t): raise NotImplementedError("The moment generating function for the " "Cauchy distribution does not exist.") def Cauchy(name, x0, gamma): r""" Create a continuous random variable with a Cauchy distribution. The density of the Cauchy distribution is given by .. math:: f(x) := \frac{1}{\pi} \arctan\left(\frac{x-x_0}{\gamma}\right) +\frac{1}{2} Parameters ========== x0 : Real number, the location gamma : Real number, `\gamma > 0`, the scale Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Cauchy, density >>> from sympy import Symbol >>> x0 = Symbol("x0") >>> gamma = Symbol("gamma", positive=True) >>> z = Symbol("z") >>> X = Cauchy("x", x0, gamma) >>> density(X)(z) 1/(pigamma(1 + (-x0 + z)2/gamma2)) References ========== .. [1] https://en.wikipedia.org/wiki/Cauchy_distribution .. [2] http://mathworld.wolfram.com/CauchyDistribution.html """ return rv(name, CauchyDistribution, (x0, gamma)) #------------------------------------------------------------------------------- # Chi distribution ------------------------------------------------------------- class ChiDistribution(SingleContinuousDistribution): _argnames = ('k',) set = Interval(0, oo) def pdf(self, x): return 2*(1 - self.k/2)x*(self.k - 1)exp(-x2/2)/gamma(self.k/2) def _characteristic_function(self, t): k = self.k part_1 = hyper((k/2,), (S(1)/2,), -t2/2) part_2 = Itsqrt(2)gamma((k+1)/2)/gamma(k/2) part_3 = hyper(((k+1)/2,), (S(3)/2,), -t2/2) return part_1 + part_2part_3 def _moment_generating_function(self, t): k = self.k part_1 = hyper((k / 2,), (S(1) / 2,), t ** 2 / 2) part_2 = t * sqrt(2) * gamma((k + 1) / 2) / gamma(k / 2) part_3 = hyper(((k + 1) / 2,), (S(3) / 2,), t ** 2 / 2) return part_1 + part_2 * part_3 def Chi(name, k): r""" Create a continuous random variable with a Chi distribution. The density of the Chi distribution is given by .. math:: f(x) := \frac{2^{1-k/2}x^{k-1}e^{-x^2/2}}{\Gamma(k/2)} with :math:`x \geq 0`. Parameters ========== k : A positive Integer, `k > 0`, the number of degrees of freedom Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Chi, density, E, std >>> from sympy import Symbol, simplify >>> k = Symbol("k", integer=True) >>> z = Symbol("z") >>> X = Chi("x", k) >>> density(X)(z) 2*(-k/2 + 1)z*(k - 1)exp(-z2/2)/gamma(k/2) References ========== .. [1] https://en.wikipedia.org/wiki/Chi_distribution .. [2] http://mathworld.wolfram.com/ChiDistribution.html """ return rv(name, ChiDistribution, (k,)) #------------------------------------------------------------------------------- # Non-central Chi distribution ------------------------------------------------- class ChiNoncentralDistribution(SingleContinuousDistribution): _argnames = ('k', 'l') set = Interval(0, oo) def pdf(self, x): k, l = self.k, self.l return exp(-(x2+l*2)/2)x*kl / (lx)(k/2) besseli(k/2-1, lx) def ChiNoncentral(name, k, l): r""" Create a continuous random variable with a non-central Chi distribution. The density of the non-central Chi distribution is given by .. math:: f(x) := \frac{e^{-(x^2+\lambda^2)/2} x^k\lambda} {(\lambda x)^{k/2}} I_{k/2-1}(\lambda x) with `x \geq 0`. Here, `I_\nu (x)` is the :ref:`modified Bessel function of the first kind <besseli>`. Parameters ========== k : A positive Integer, `k > 0`, the number of degrees of freedom l : Shift parameter Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import ChiNoncentral, density, E, std >>> from sympy import Symbol, simplify >>> k = Symbol("k", integer=True) >>> l = Symbol("l") >>> z = Symbol("z") >>> X = ChiNoncentral("x", k, l) >>> density(X)(z) lz*k(lz)(-k/2)exp(-l2/2 - z2/2)besseli(k/2 - 1, lz) References ========== .. [1] https://en.wikipedia.org/wiki/Noncentral_chi_distribution """ return rv(name, ChiNoncentralDistribution, (k, l)) #------------------------------------------------------------------------------- # Chi squared distribution ----------------------------------------------------- class ChiSquaredDistribution(SingleContinuousDistribution): _argnames = ('k',) set = Interval(0, oo) def pdf(self, x): k = self.k return 1/(2*(k/2)gamma(k/2))x(k/2 - 1)exp(-x/2) def _cdf(self, x): k = self.k return Piecewise( (S.One/gamma(k/2)lowergamma(k/2, x/2), x >= 0), (0, True) ) def _characteristic_function(self, t): return (1 - 2It)(-self.k/2) def _moment_generating_function(self, t): return (1 - 2t)(-self.k/2) def ChiSquared(name, k): r""" Create a continuous random variable with a Chi-squared distribution. The density of the Chi-squared distribution is given by .. math:: f(x) := \frac{1}{2^{\frac{k}{2}}\Gamma\left(\frac{k}{2}\right)} x^{\frac{k}{2}-1} e^{-\frac{x}{2}} with :math:`x \geq 0`. Parameters ========== k : A positive Integer, `k > 0`, the number of degrees of freedom Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import ChiSquared, density, E, variance >>> from sympy import Symbol, simplify, gammasimp, expand_func >>> k = Symbol("k", integer=True, positive=True) >>> z = Symbol("z") >>> X = ChiSquared("x", k) >>> density(X)(z) 2(-k/2)z(k/2 - 1)exp(-z/2)/gamma(k/2) >>> gammasimp(E(X)) k >>> simplify(expand_func(variance(X))) 2k References ========== .. [1] https://en.wikipedia.org/wiki/Chi_squared_distribution .. [2] http://mathworld.wolfram.com/Chi-SquaredDistribution.html """ return rv(name, ChiSquaredDistribution, (k, )) #------------------------------------------------------------------------------- # Dagum distribution ----------------------------------------------------------- class DagumDistribution(SingleContinuousDistribution): _argnames = ('p', 'a', 'b') def pdf(self, x): p, a, b = self.p, self.a, self.b return ap/x((x/b)(ap)/(((x/b)a + 1)(p + 1))) def _cdf(self, x): p, a, b = self.p, self.a, self.b return Piecewise(((S.One + (S(x)/b)-a)-p, x>=0), (S.Zero, True)) def Dagum(name, p, a, b): r""" Create a continuous random variable with a Dagum distribution. The density of the Dagum distribution is given by .. math:: f(x) := \frac{a p}{x} \left( \frac{\left(\tfrac{x}{b}\right)^{a p}} {\left(\left(\tfrac{x}{b}\right)^a + 1 \right)^{p+1}} \right) with :math:`x > 0`. Parameters ========== p : Real number, `p > 0`, a shape a : Real number, `a > 0`, a shape b : Real number, `b > 0`, a scale Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Dagum, density, cdf >>> from sympy import Symbol, simplify >>> p = Symbol("p", positive=True) >>> b = Symbol("b", positive=True) >>> a = Symbol("a", positive=True) >>> z = Symbol("z") >>> X = Dagum("x", p, a, b) >>> density(X)(z) ap(z/b)*(ap)((z/b)a + 1)(-p - 1)/z >>> cdf(X)(z) Piecewise(((1 + (z/b)(-a))(-p), z >= 0), (0, True)) References ========== .. [1] https://en.wikipedia.org/wiki/Dagum_distribution """ return rv(name, DagumDistribution, (p, a, b)) #------------------------------------------------------------------------------- # Erlang distribution ---------------------------------------------------------- def Erlang(name, k, l): r""" Create a continuous random variable with an Erlang distribution. The density of the Erlang distribution is given by .. math:: f(x) := \frac{\lambda^k x^{k-1} e^{-\lambda x}}{(k-1)!} with :math:`x \in [0,\infty]`. Parameters ========== k : Integer l : Real number, `\lambda > 0`, the rate Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Erlang, density, cdf, E, variance >>> from sympy import Symbol, simplify, pprint >>> k = Symbol("k", integer=True, positive=True) >>> l = Symbol("l", positive=True) >>> z = Symbol("z") >>> X = Erlang("x", k, l) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) k k - 1 -lz l z e --------------- Gamma(k) >>> C = cdf(X, meijerg=True)(z) >>> pprint(C, use_unicode=False) / -2Ipik \|ke lowergamma(k, lz) \|------------------------------- for z >= 0 < Gamma(k + 1) \| \| 0 otherwise \ >>> simplify(E(X)) k/l >>> simplify(variance(X)) k/l*2 References ========== .. [1] https://en.wikipedia.org/wiki/Erlang_distribution .. [2] http://mathworld.wolfram.com/ErlangDistribution.html """ return rv(name, GammaDistribution, (k, S.One/l)) #------------------------------------------------------------------------------- # Exponential distribution ----------------------------------------------------- class ExponentialDistribution(SingleContinuousDistribution): _argnames = ('rate',) set = Interval(0, oo) @staticmethod def check(rate): _value_check(rate > 0, "Rate must be positive.") def pdf(self, x): return self.rate exp(-self.ratex) def sample(self): return random.expovariate(self.rate) def _cdf(self, x): return Piecewise( (S.One - exp(-self.ratex), x >= 0), (0, True), ) def _characteristic_function(self, t): rate = self.rate return rate / (rate - It) def _moment_generating_function(self, t): rate = self.rate return rate / (rate - t) def Exponential(name, rate): r""" Create a continuous random variable with an Exponential distribution. The density of the exponential distribution is given by .. math:: f(x) := \lambda \exp(-\lambda x) with `x > 0`. Note that the expected value is `1/\lambda`. Parameters ========== rate : A positive Real number, `\lambda > 0`, the rate (or inverse scale/inverse mean) Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Exponential, density, cdf, E >>> from sympy.stats import variance, std, skewness >>> from sympy import Symbol >>> l = Symbol("lambda", positive=True) >>> z = Symbol("z") >>> X = Exponential("x", l) >>> density(X)(z) lambdaexp(-lambdaz) >>> cdf(X)(z) Piecewise((1 - exp(-lambdaz), z >= 0), (0, True)) >>> E(X) 1/lambda >>> variance(X) lambda*(-2) >>> skewness(X) 2 >>> X = Exponential('x', 10) >>> density(X)(z) 10exp(-10z) >>> E(X) 1/10 >>> std(X) 1/10 References ========== .. [1] https://en.wikipedia.org/wiki/Exponential_distribution .. [2] http://mathworld.wolfram.com/ExponentialDistribution.html """ return rv(name, ExponentialDistribution, (rate, )) #------------------------------------------------------------------------------- # F distribution --------------------------------------------------------------- class FDistributionDistribution(SingleContinuousDistribution): _argnames = ('d1', 'd2') set = Interval(0, oo) def pdf(self, x): d1, d2 = self.d1, self.d2 return (sqrt((d1x)*d1d2*d2 / (d1x+d2)*(d1+d2)) / (x beta_fn(d1/2, d2/2))) def _moment_generating_function(self, t): raise NotImplementedError('The moment generating function for the ' 'F-distribution does not exist.') def FDistribution(name, d1, d2): r""" Create a continuous random variable with a F distribution. The density of the F distribution is given by .. math:: f(x) := \frac{\sqrt{\frac{(d_1 x)^{d_1} d_2^{d_2}} {(d_1 x + d_2)^{d_1 + d_2}}}} {x \mathrm{B} \left(\frac{d_1}{2}, \frac{d_2}{2}\right)} with :math:`x > 0`. Parameters ========== d1 : `d_1 > 0`, where d_1 is the degrees of freedom (n_1 - 1) d2 : `d_2 > 0`, where d_2 is the degrees of freedom (n_2 - 1) Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import FDistribution, density >>> from sympy import Symbol, simplify, pprint >>> d1 = Symbol("d1", positive=True) >>> d2 = Symbol("d2", positive=True) >>> z = Symbol("z") >>> X = FDistribution("x", d1, d2) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) d2 -- ______________________________ 2 / d1 -d1 - d2 d2 \/ (d1z) (d1z + d2) -------------------------------------- /d1 d2\ zB\|--, --\| \2 2 / References ========== .. [1] https://en.wikipedia.org/wiki/F-distribution .. [2] http://mathworld.wolfram.com/F-Distribution.html """ return rv(name, FDistributionDistribution, (d1, d2)) #------------------------------------------------------------------------------- # Fisher Z distribution -------------------------------------------------------- class FisherZDistribution(SingleContinuousDistribution): _argnames = ('d1', 'd2') def pdf(self, x): d1, d2 = self.d1, self.d2 return (2d1*(d1/2)d2*(d2/2) / beta_fn(d1/2, d2/2) exp(d1x) / (d1exp(2x)+d2)((d1+d2)/2)) def FisherZ(name, d1, d2): r""" Create a Continuous Random Variable with an Fisher's Z distribution. The density of the Fisher's Z distribution is given by .. math:: f(x) := \frac{2d_1^{d_1/2} d_2^{d_2/2}} {\mathrm{B}(d_1/2, d_2/2)} \frac{e^{d_1z}}{\left(d_1e^{2z}+d_2\right)^{\left(d_1+d_2\right)/2}} .. TODO - What is the difference between these degrees of freedom? Parameters ========== d1 : `d_1 > 0`, degree of freedom d2 : `d_2 > 0`, degree of freedom Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import FisherZ, density >>> from sympy import Symbol, simplify, pprint >>> d1 = Symbol("d1", positive=True) >>> d2 = Symbol("d2", positive=True) >>> z = Symbol("z") >>> X = FisherZ("x", d1, d2) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) d1 d2 d1 d2 - -- - -- -- -- 2 2 2 2 / 2z \ d1z 2d1 d2 \d1e + d2/ e ----------------------------------------- /d1 d2\ B\|--, --\| \2 2 / References ========== .. [1] https://en.wikipedia.org/wiki/Fisher%27s_z-distribution .. [2] http://mathworld.wolfram.com/Fishersz-Distribution.html """ return rv(name, FisherZDistribution, (d1, d2)) #------------------------------------------------------------------------------- # Frechet distribution --------------------------------------------------------- class FrechetDistribution(SingleContinuousDistribution): _argnames = ('a', 's', 'm') set = Interval(0, oo) def __new__(cls, a, s=1, m=0): a, s, m = list(map(sympify, (a, s, m))) return Basic.__new__(cls, a, s, m) def pdf(self, x): a, s, m = self.a, self.s, self.m return a/s * ((x-m)/s)*(-1-a) exp(-((x-m)/s)(-a)) def _cdf(self, x): a, s, m = self.a, self.s, self.m return Piecewise((exp(-((x-m)/s)(-a)), x >= m), (S.Zero, True)) def Frechet(name, a, s=1, m=0): r""" Create a continuous random variable with a Frechet distribution. The density of the Frechet distribution is given by .. math:: f(x) := \frac{\alpha}{s} \left(\frac{x-m}{s}\right)^{-1-\alpha} e^{-(\frac{x-m}{s})^{-\alpha}} with :math:`x \geq m`. Parameters ========== a : Real number, :math:`a \in \left(0, \infty\right)` the shape s : Real number, :math:`s \in \left(0, \infty\right)` the scale m : Real number, :math:`m \in \left(-\infty, \infty\right)` the minimum Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Frechet, density, E, std, cdf >>> from sympy import Symbol, simplify >>> a = Symbol("a", positive=True) >>> s = Symbol("s", positive=True) >>> m = Symbol("m", real=True) >>> z = Symbol("z") >>> X = Frechet("x", a, s, m) >>> density(X)(z) a((-m + z)/s)(-a - 1)exp(-((-m + z)/s)(-a))/s >>> cdf(X)(z) Piecewise((exp(-((-m + z)/s)(-a)), m <= z), (0, True)) References ========== .. [1] https://en.wikipedia.org/wiki/Fr%C3%A9chet_distribution """ return rv(name, FrechetDistribution, (a, s, m)) #------------------------------------------------------------------------------- # Gamma distribution ----------------------------------------------------------- class GammaDistribution(SingleContinuousDistribution): _argnames = ('k', 'theta') set = Interval(0, oo) @staticmethod def check(k, theta): _value_check(k > 0, "k must be positive") _value_check(theta > 0, "Theta must be positive") def pdf(self, x): k, theta = self.k, self.theta return x*(k - 1) exp(-x/theta) / (gamma(k)thetak) def sample(self): return random.gammavariate(self.k, self.theta) def _cdf(self, x): k, theta = self.k, self.theta return Piecewise( (lowergamma(k, S(x)/theta)/gamma(k), x > 0), (S.Zero, True)) def _characteristic_function(self, t): return (1 - self.thetaIt)(-self.k) def _moment_generating_function(self, t): return (1- self.thetat)*(-self.k) def Gamma(name, k, theta): r""" Create a continuous random variable with a Gamma distribution. The density of the Gamma distribution is given by .. math:: f(x) := \frac{1}{\Gamma(k) \theta^k} x^{k - 1} e^{-\frac{x}{\theta}} with :math:`x \in [0,1]`. Parameters ========== k : Real number, `k > 0`, a shape theta : Real number, `\theta > 0`, a scale Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Gamma, density, cdf, E, variance >>> from sympy import Symbol, pprint, simplify >>> k = Symbol("k", positive=True) >>> theta = Symbol("theta", positive=True) >>> z = Symbol("z") >>> X = Gamma("x", k, theta) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) -z ----- -k k - 1 theta theta z e --------------------- Gamma(k) >>> C = cdf(X, meijerg=True)(z) >>> pprint(C, use_unicode=False) / / z \ \|klowergamma\|k, -----\| \| \ theta/ <---------------------- for z >= 0 \| Gamma(k + 1) \| \ 0 otherwise >>> E(X) ktheta >>> V = simplify(variance(X)) >>> pprint(V, use_unicode=False) 2 ktheta References ========== .. [1] https://en.wikipedia.org/wiki/Gamma_distribution .. [2] http://mathworld.wolfram.com/GammaDistribution.html """ return rv(name, GammaDistribution, (k, theta)) #------------------------------------------------------------------------------- # Inverse Gamma distribution --------------------------------------------------- class GammaInverseDistribution(SingleContinuousDistribution): _argnames = ('a', 'b') set = Interval(0, oo) @staticmethod def check(a, b): _value_check(a > 0, "alpha must be positive") _value_check(b > 0, "beta must be positive") def pdf(self, x): a, b = self.a, self.b return b*a/gamma(a) x*(-a-1) exp(-b/x) def _cdf(self, x): a, b = self.a, self.b return Piecewise((uppergamma(a,b/x)/gamma(a), x > 0), (S.Zero, True)) def sample(self): scipy = import_module('scipy') if scipy: from scipy.stats import invgamma return invgamma.rvs(float(self.a), 0, float(self.b)) else: raise NotImplementedError('Sampling the inverse Gamma Distribution requires Scipy.') def _characteristic_function(self, t): a, b = self.a, self.b return 2 * (-Ibt)*(a/2) besselk(sqrt(-4Ibt)) / gamma(a) def _moment_generating_function(self, t): raise NotImplementedError('The moment generating function for the ' 'gamma inverse distribution does not exist.') def GammaInverse(name, a, b): r""" Create a continuous random variable with an inverse Gamma distribution. The density of the inverse Gamma distribution is given by .. math:: f(x) := \frac{\beta^\alpha}{\Gamma(\alpha)} x^{-\alpha - 1} \exp\left(\frac{-\beta}{x}\right) with :math:`x > 0`. Parameters ========== a : Real number, `a > 0` a shape b : Real number, `b > 0` a scale Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import GammaInverse, density, cdf, E, variance >>> from sympy import Symbol, pprint >>> a = Symbol("a", positive=True) >>> b = Symbol("b", positive=True) >>> z = Symbol("z") >>> X = GammaInverse("x", a, b) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) -b --- a -a - 1 z b z e --------------- Gamma(a) >>> cdf(X)(z) Piecewise((uppergamma(a, b/z)/gamma(a), z > 0), (0, True)) References ========== .. [1] https://en.wikipedia.org/wiki/Inverse-gamma_distribution """ return rv(name, GammaInverseDistribution, (a, b)) #------------------------------------------------------------------------------- # Gumbel distribution -------------------------------------------------------- class GumbelDistribution(SingleContinuousDistribution): _argnames = ('beta', 'mu') set = Interval(-oo, oo) def pdf(self, x): beta, mu = self.beta, self.mu return (1/beta)exp(-((x-mu)/beta)+exp(-((x-mu)/beta))) def _characteristic_function(self, t): return gamma(1 - Iself.betat) * exp(Iself.mut) def _moment_generating_function(self, t): return gamma(1 - self.betat) exp(Iself.mut) def Gumbel(name, beta, mu): r""" Create a Continuous Random Variable with Gumbel distribution. The density of the Gumbel distribution is given by .. math:: f(x) := \exp \left( -exp \left( x + \exp \left( -x \right) \right) \right) with ::math 'x \in [ - \inf, \inf ]'. Parameters ========== mu: Real number, 'mu' is a location beta: Real number, 'beta > 0' is a scale Returns ========== A RandomSymbol Examples ========== >>> from sympy.stats import Gumbel, density, E, variance >>> from sympy import Symbol, simplify, pprint >>> x = Symbol("x") >>> mu = Symbol("mu") >>> beta = Symbol("beta", positive=True) >>> X = Gumbel("x", beta, mu) >>> density(X)(x) exp(exp(-(-mu + x)/beta) - (-mu + x)/beta)/beta References ========== .. [1] http://mathworld.wolfram.com/GumbelDistribution.html .. [2] https://en.wikipedia.org/wiki/Gumbel_distribution """ return rv(name, GumbelDistribution, (beta, mu)) #------------------------------------------------------------------------------- # Gompertz distribution -------------------------------------------------------- class GompertzDistribution(SingleContinuousDistribution): _argnames = ('b', 'eta') set = Interval(0, oo) @staticmethod def check(b, eta): _value_check(b > 0, "b must be positive") _value_check(eta > 0, "eta must be positive") def pdf(self, x): eta, b = self.eta, self.b return betaexp(bx)exp(eta)exp(-etaexp(bx)) def _moment_generating_function(self, t): eta, b = self.eta, self.b return eta exp(eta) * expint(t/b, eta) def Gompertz(name, b, eta): r""" Create a Continuous Random Variable with Gompertz distribution. The density of the Gompertz distribution is given by .. math:: f(x) := b \eta e^{b x} e^{\eta} \exp \left(-\eta e^{bx} \right) with :math: 'x \in [0, \inf)'. Parameters ========== b: Real number, 'b > 0' a scale eta: Real number, 'eta > 0' a shape Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Gompertz, density, E, variance >>> from sympy import Symbol, simplify, pprint >>> b = Symbol("b", positive=True) >>> eta = Symbol("eta", positive=True) >>> z = Symbol("z") >>> X = Gompertz("x", b, eta) >>> density(X)(z) betaexp(eta)exp(bz)exp(-etaexp(bz)) References ========== .. [1] https://en.wikipedia.org/wiki/Gompertz_distribution """ return rv(name, GompertzDistribution, (b, eta)) #------------------------------------------------------------------------------- # Kumaraswamy distribution ----------------------------------------------------- class KumaraswamyDistribution(SingleContinuousDistribution): _argnames = ('a', 'b') set = Interval(0, oo) @staticmethod def check(a, b): _value_check(a > 0, "a must be positive") _value_check(b > 0, "b must be positive") def pdf(self, x): a, b = self.a, self.b return a b * x*(a-1) (1-xa)(b-1) def _cdf(self, x): a, b = self.a, self.b return Piecewise( (S.Zero, x < S.Zero), (1 - (1 - xa)b, x <= S.One), (S.One, True)) def Kumaraswamy(name, a, b): r""" Create a Continuous Random Variable with a Kumaraswamy distribution. The density of the Kumaraswamy distribution is given by .. math:: f(x) := a b x^{a-1} (1-x^a)^{b-1} with :math:`x \in [0,1]`. Parameters ========== a : Real number, `a > 0` a shape b : Real number, `b > 0` a shape Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Kumaraswamy, density, E, variance, cdf >>> from sympy import Symbol, simplify, pprint >>> a = Symbol("a", positive=True) >>> b = Symbol("b", positive=True) >>> z = Symbol("z") >>> X = Kumaraswamy("x", a, b) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) b - 1 a - 1 / a \ abz \- z + 1/ >>> cdf(X)(z) Piecewise((0, z < 0), (-(-za + 1)b + 1, z <= 1), (1, True)) References ========== .. [1] https://en.wikipedia.org/wiki/Kumaraswamy_distribution """ return rv(name, KumaraswamyDistribution, (a, b)) #------------------------------------------------------------------------------- # Laplace distribution --------------------------------------------------------- class LaplaceDistribution(SingleContinuousDistribution): _argnames = ('mu', 'b') def pdf(self, x): mu, b = self.mu, self.b return 1/(2b)exp(-Abs(x - mu)/b) def _cdf(self, x): mu, b = self.mu, self.b return Piecewise( (S.Halfexp((x - mu)/b), x < mu), (S.One - S.Halfexp(-(x - mu)/b), x >= mu) ) def _characteristic_function(self, t): return exp(self.muIt) / (1 + self.b2t*2) def _moment_generating_function(self, t): return exp(self.mut) / (1 - self.b*2t*2) def Laplace(name, mu, b): r""" Create a continuous random variable with a Laplace distribution. The density of the Laplace distribution is given by .. math:: f(x) := \frac{1}{2 b} \exp \left(-\frac{\|x-\mu\|}b \right) Parameters ========== mu : Real number or a list/matrix, the location (mean) or the location vector b : Real number or a positive definite matrix, representing a scale or the covariance matrix. Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Laplace, density, cdf >>> from sympy import Symbol, pprint >>> mu = Symbol("mu") >>> b = Symbol("b", positive=True) >>> z = Symbol("z") >>> X = Laplace("x", mu, b) >>> density(X)(z) exp(-Abs(mu - z)/b)/(2b) >>> cdf(X)(z) Piecewise((exp((-mu + z)/b)/2, mu > z), (-exp((mu - z)/b)/2 + 1, True)) >>> L = Laplace('L', [1, 2], [[1, 0], [0, 1]]) >>> pprint(density(L)(1, 2), use_unicode=False) 5 / ____\ e besselk\0, \/ 35 / --------------------- pi References ========== .. [1] https://en.wikipedia.org/wiki/Laplace_distribution .. [2] http://mathworld.wolfram.com/LaplaceDistribution.html """ if isinstance(mu, (list, MatrixBase)) and\ isinstance(b, (list, MatrixBase)): from sympy.stats.joint_rv_types import MultivariateLaplaceDistribution return multivariate_rv( MultivariateLaplaceDistribution, name, mu, b) return rv(name, LaplaceDistribution, (mu, b)) #------------------------------------------------------------------------------- # Logistic distribution -------------------------------------------------------- class LogisticDistribution(SingleContinuousDistribution): _argnames = ('mu', 's') def pdf(self, x): mu, s = self.mu, self.s return exp(-(x - mu)/s)/(s(1 + exp(-(x - mu)/s))*2) def _cdf(self, x): mu, s = self.mu, self.s return S.One/(1 + exp(-(x - mu)/s)) def _characteristic_function(self, t): return Piecewise((exp(Itself.mu) piself.st / sinh(piself.st), Ne(t, 0)), (S.One, True)) def _moment_generating_function(self, t): return exp(self.mut) Beta(1 - self.st, 1 + self.st) def Logistic(name, mu, s): r""" Create a continuous random variable with a logistic distribution. The density of the logistic distribution is given by .. math:: f(x) := \frac{e^{-(x-\mu)/s}} {s\left(1+e^{-(x-\mu)/s}\right)^2} Parameters ========== mu : Real number, the location (mean) s : Real number, `s > 0` a scale Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Logistic, density, cdf >>> from sympy import Symbol >>> mu = Symbol("mu", real=True) >>> s = Symbol("s", positive=True) >>> z = Symbol("z") >>> X = Logistic("x", mu, s) >>> density(X)(z) exp((mu - z)/s)/(s(exp((mu - z)/s) + 1)2) >>> cdf(X)(z) 1/(exp((mu - z)/s) + 1) References ========== .. [1] https://en.wikipedia.org/wiki/Logistic_distribution .. [2] http://mathworld.wolfram.com/LogisticDistribution.html """ return rv(name, LogisticDistribution, (mu, s)) #------------------------------------------------------------------------------- # Log Normal distribution ------------------------------------------------------ class LogNormalDistribution(SingleContinuousDistribution): _argnames = ('mean', 'std') set = Interval(0, oo) def pdf(self, x): mean, std = self.mean, self.std return exp(-(log(x) - mean)2 / (2std*2)) / (xsqrt(2pi)std) def sample(self): return random.lognormvariate(self.mean, self.std) def _cdf(self, x): mean, std = self.mean, self.std return Piecewise( (S.Half + S.Halferf((log(x) - mean)/sqrt(2)/std), x > 0), (S.Zero, True) ) def _moment_generating_function(self, t): raise NotImplementedError('Moment generating function of the log-normal distribution is not defined.') def LogNormal(name, mean, std): r""" Create a continuous random variable with a log-normal distribution. The density of the log-normal distribution is given by .. math:: f(x) := \frac{1}{x\sqrt{2\pi\sigma^2}} e^{-\frac{\left(\ln x-\mu\right)^2}{2\sigma^2}} with :math:`x \geq 0`. Parameters ========== mu : Real number, the log-scale sigma : Real number, :math:`\sigma^2 > 0` a shape Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import LogNormal, density >>> from sympy import Symbol, simplify, pprint >>> mu = Symbol("mu", real=True) >>> sigma = Symbol("sigma", positive=True) >>> z = Symbol("z") >>> X = LogNormal("x", mu, sigma) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) 2 -(-mu + log(z)) ----------------- 2 ___ 2sigma \/ 2 e ------------------------ ____ 2\/ pi sigmaz >>> X = LogNormal('x', 0, 1) # Mean 0, standard deviation 1 >>> density(X)(z) sqrt(2)exp(-log(z)2/2)/(2sqrt(pi)z) References ========== .. [1] https://en.wikipedia.org/wiki/Lognormal .. [2] http://mathworld.wolfram.com/LogNormalDistribution.html """ return rv(name, LogNormalDistribution, (mean, std)) #------------------------------------------------------------------------------- # Maxwell distribution --------------------------------------------------------- class MaxwellDistribution(SingleContinuousDistribution): _argnames = ('a',) set = Interval(0, oo) def pdf(self, x): a = self.a return sqrt(2/pi)x*2exp(-x*2/(2a2))/a3 def Maxwell(name, a): r""" Create a continuous random variable with a Maxwell distribution. The density of the Maxwell distribution is given by .. math:: f(x) := \sqrt{\frac{2}{\pi}} \frac{x^2 e^{-x^2/(2a^2)}}{a^3} with :math:`x \geq 0`. .. TODO - what does the parameter mean? Parameters ========== a : Real number, `a > 0` Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Maxwell, density, E, variance >>> from sympy import Symbol, simplify >>> a = Symbol("a", positive=True) >>> z = Symbol("z") >>> X = Maxwell("x", a) >>> density(X)(z) sqrt(2)z2exp(-z*2/(2a*2))/(sqrt(pi)a*3) >>> E(X) 2sqrt(2)a/sqrt(pi) >>> simplify(variance(X)) a2(-8 + 3pi)/pi References ========== .. [1] https://en.wikipedia.org/wiki/Maxwell_distribution .. [2] http://mathworld.wolfram.com/MaxwellDistribution.html """ return rv(name, MaxwellDistribution, (a, )) #------------------------------------------------------------------------------- # Nakagami distribution -------------------------------------------------------- class NakagamiDistribution(SingleContinuousDistribution): _argnames = ('mu', 'omega') set = Interval(0, oo) def pdf(self, x): mu, omega = self.mu, self.omega return 2mu*mu/(gamma(mu)omega*mu)x*(2mu - 1)exp(-mu/omegax*2) def _cdf(self, x): mu, omega = self.mu, self.omega return Piecewise( (lowergamma(mu, (mu/omega)x*2)/gamma(mu), x > 0), (S.Zero, True)) def Nakagami(name, mu, omega): r""" Create a continuous random variable with a Nakagami distribution. The density of the Nakagami distribution is given by .. math:: f(x) := \frac{2\mu^\mu}{\Gamma(\mu)\omega^\mu} x^{2\mu-1} \exp\left(-\frac{\mu}{\omega}x^2 \right) with :math:`x > 0`. Parameters ========== mu : Real number, `\mu \geq \frac{1}{2}` a shape omega : Real number, `\omega > 0`, the spread Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Nakagami, density, E, variance, cdf >>> from sympy import Symbol, simplify, pprint >>> mu = Symbol("mu", positive=True) >>> omega = Symbol("omega", positive=True) >>> z = Symbol("z") >>> X = Nakagami("x", mu, omega) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) 2 -muz ------- mu -mu 2mu - 1 omega 2mu omega z e ---------------------------------- Gamma(mu) >>> simplify(E(X)) sqrt(mu)sqrt(omega)gamma(mu + 1/2)/gamma(mu + 1) >>> V = simplify(variance(X)) >>> pprint(V, use_unicode=False) 2 omegaGamma (mu + 1/2) omega - ----------------------- Gamma(mu)Gamma(mu + 1) >>> cdf(X)(z) Piecewise((lowergamma(mu, muz2/omega)/gamma(mu), z > 0), (0, True)) References ========== .. [1] https://en.wikipedia.org/wiki/Nakagami_distribution """ return rv(name, NakagamiDistribution, (mu, omega)) #------------------------------------------------------------------------------- # Normal distribution ---------------------------------------------------------- class NormalDistribution(SingleContinuousDistribution): _argnames = ('mean', 'std') @staticmethod def check(mean, std): _value_check(std > 0, "Standard deviation must be positive") def pdf(self, x): return exp(-(x - self.mean)2 / (2self.std2)) / (sqrt(2pi)self.std) def sample(self): return random.normalvariate(self.mean, self.std) def _cdf(self, x): mean, std = self.mean, self.std return erf(sqrt(2)(-mean + x)/(2std))/2 + S.Half def _characteristic_function(self, t): mean, std = self.mean, self.std return exp(Imeant - std2t*2/2) def _moment_generating_function(self, t): mean, std = self.mean, self.std return exp(meant + std*2t*2/2) def Normal(name, mean, std): r""" Create a continuous random variable with a Normal distribution. The density of the Normal distribution is given by .. math:: f(x) := \frac{1}{\sigma\sqrt{2\pi}} e^{ -\frac{(x-\mu)^2}{2\sigma^2} } Parameters ========== mu : Real number or a list representing the mean or the mean vector sigma : Real number or a positive definite sqaure matrix, :math:`\sigma^2 > 0` the variance Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Normal, density, E, std, cdf, skewness >>> from sympy import Symbol, simplify, pprint, factor, together, factor_terms >>> mu = Symbol("mu") >>> sigma = Symbol("sigma", positive=True) >>> z = Symbol("z") >>> y = Symbol("y") >>> X = Normal("x", mu, sigma) >>> density(X)(z) sqrt(2)exp(-(-mu + z)*2/(2sigma*2))/(2sqrt(pi)sigma) >>> C = simplify(cdf(X))(z) # it needs a little more help... >>> pprint(C, use_unicode=False) / ___ \ \|\/ 2 (-mu + z)\| erf\|---------------\| \ 2sigma / 1 -------------------- + - 2 2 >>> simplify(skewness(X)) 0 >>> X = Normal("x", 0, 1) # Mean 0, standard deviation 1 >>> density(X)(z) sqrt(2)exp(-z*2/2)/(2sqrt(pi)) >>> E(2X + 1) 1 >>> simplify(std(2X + 1)) 2 >>> m = Normal('X', [1, 2], [[2, 1], [1, 2]]) >>> from sympy.stats.joint_rv import marginal_distribution >>> pprint(density(m)(y, z)) / y 1\ /2y z\ / z \ / y 2z \ \|- - + -\|\|--- - -\| + \|- - + 1\|\|- - + --- - 1\| ___ \ 2 2/ \ 3 3/ \ 2 / \ 3 3 / \/ 3 e ------------------------------------------------------ 6pi >>> marginal_distribution(m, m[0])(1) 1/(2sqrt(pi)) References ========== .. [1] https://en.wikipedia.org/wiki/Normal_distribution .. [2] http://mathworld.wolfram.com/NormalDistributionFunction.html """ if isinstance(mean, (list, MatrixBase)) and\ isinstance(std, (list, MatrixBase)): from sympy.stats.joint_rv_types import MultivariateNormalDistribution return multivariate_rv( MultivariateNormalDistribution, name, mean, std) return rv(name, NormalDistribution, (mean, std)) #------------------------------------------------------------------------------- # Pareto distribution ---------------------------------------------------------- class ParetoDistribution(SingleContinuousDistribution): _argnames = ('xm', 'alpha') @property def set(self): return Interval(self.xm, oo) @staticmethod def check(xm, alpha): _value_check(xm > 0, "Xm must be positive") _value_check(alpha > 0, "Alpha must be positive") def pdf(self, x): xm, alpha = self.xm, self.alpha return alpha xmalpha / x(alpha + 1) def sample(self): return random.paretovariate(self.alpha) def _cdf(self, x): xm, alpha = self.xm, self.alpha return Piecewise( (S.One - xmalpha/xalpha, x>=xm), (0, True), ) def _moment_generating_function(self, t): xm, alpha = self.xm, self.alpha return alpha * (-xmt)alpha uppergamma(-alpha, -xmt) def _characteristic_function(self, t): xm, alpha = self.xm, self.alpha return alpha (-I * xm * t) ** alpha * uppergamma(-alpha, -I * xm * t) def Pareto(name, xm, alpha): r""" Create a continuous random variable with the Pareto distribution. The density of the Pareto distribution is given by .. math:: f(x) := \frac{\alpha\,x_m^\alpha}{x^{\alpha+1}} with :math:`x \in [x_m,\infty]`. Parameters ========== xm : Real number, `x_m > 0`, a scale alpha : Real number, `\alpha > 0`, a shape Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Pareto, density >>> from sympy import Symbol >>> xm = Symbol("xm", positive=True) >>> beta = Symbol("beta", positive=True) >>> z = Symbol("z") >>> X = Pareto("x", xm, beta) >>> density(X)(z) betaxmbetaz(-beta - 1) References ========== .. [1] https://en.wikipedia.org/wiki/Pareto_distribution .. [2] http://mathworld.wolfram.com/ParetoDistribution.html """ return rv(name, ParetoDistribution, (xm, alpha)) #------------------------------------------------------------------------------- # QuadraticU distribution ------------------------------------------------------ class QuadraticUDistribution(SingleContinuousDistribution): _argnames = ('a', 'b') @property def set(self): return Interval(self.a, self.b) def pdf(self, x): a, b = self.a, self.b alpha = 12 / (b-a)3 beta = (a+b) / 2 return Piecewise( (alpha * (x-beta)*2, And(a<=x, x<=b)), (S.Zero, True)) def _moment_generating_function(self, t): a, b = self.a, self.b return -3 (exp(at) (4 + (a*2 + 2a(-2 + b) + b2) t) - exp(bt) (4 + (-4b + (a + b)2) t)) / ((a-b)*3 t*2) def _characteristic_function(self, t): def _moment_generating_function(self, t): a, b = self.a, self.b return -3I(exp(Iatexp(Ibt)) * (4I - (-4b + (a+b)*2)t)) / ((a-b)*3 t*2) def QuadraticU(name, a, b): r""" Create a Continuous Random Variable with a U-quadratic distribution. The density of the U-quadratic distribution is given by .. math:: f(x) := \alpha (x-\beta)^2 with :math:`x \in [a,b]`. Parameters ========== a : Real number b : Real number, :math:`a < b` Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import QuadraticU, density, E, variance >>> from sympy import Symbol, simplify, factor, pprint >>> a = Symbol("a", real=True) >>> b = Symbol("b", real=True) >>> z = Symbol("z") >>> X = QuadraticU("x", a, b) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) / 2 \| / a b \ \|12\|- - - - + z\| \| \ 2 2 / <----------------- for And(b >= z, a <= z) \| 3 \| (-a + b) \| \ 0 otherwise References ========== .. [1] https://en.wikipedia.org/wiki/U-quadratic_distribution """ return rv(name, QuadraticUDistribution, (a, b)) #------------------------------------------------------------------------------- # RaisedCosine distribution ---------------------------------------------------- class RaisedCosineDistribution(SingleContinuousDistribution): _argnames = ('mu', 's') @property def set(self): return Interval(self.mu - self.s, self.mu + self.s) @staticmethod def check(mu, s): _value_check(s > 0, "s must be positive") def pdf(self, x): mu, s = self.mu, self.s return Piecewise( ((1+cos(pi(x-mu)/s)) / (2s), And(mu-s<=x, x<=mu+s)), (S.Zero, True)) def _characteristic_function(self, t): mu, s = self.mu, self.s return Piecewise((exp(-Ipimu/s)/2, Eq(t, -pi/s)), (exp(Ipimu/s)/2, Eq(t, pi/s)), (pi*2sin(st)exp(Imut) / (st(pi2 - s2t2)), True)) def _moment_generating_function(self, t): mu, s = self.mu, self.s return pi2 sinh(st) exp(mut) / (st(pi2 + s2t*2)) def RaisedCosine(name, mu, s): r""" Create a Continuous Random Variable with a raised cosine distribution. The density of the raised cosine distribution is given by .. math:: f(x) := \frac{1}{2s}\left(1+\cos\left(\frac{x-\mu}{s}\pi\right)\right) with :math:`x \in [\mu-s,\mu+s]`. Parameters ========== mu : Real number s : Real number, `s > 0` Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import RaisedCosine, density, E, variance >>> from sympy import Symbol, simplify, pprint >>> mu = Symbol("mu", real=True) >>> s = Symbol("s", positive=True) >>> z = Symbol("z") >>> X = RaisedCosine("x", mu, s) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) / /pi(-mu + z)\ \|cos\|------------\| + 1 \| \ s / <--------------------- for And(z >= mu - s, z <= mu + s) \| 2s \| \ 0 otherwise References ========== .. [1] https://en.wikipedia.org/wiki/Raised_cosine_distribution """ return rv(name, RaisedCosineDistribution, (mu, s)) #------------------------------------------------------------------------------- # Rayleigh distribution -------------------------------------------------------- class RayleighDistribution(SingleContinuousDistribution): _argnames = ('sigma',) set = Interval(0, oo) def pdf(self, x): sigma = self.sigma return x/sigma2exp(-x*2/(2sigma*2)) def _characteristic_function(self, t): sigma = self.sigma return 1 - sigmatexp(-sigma2t*2/2) sqrt(pi/2) * (erfi(sigmat/sqrt(2)) - I) def _moment_generating_function(self, t): sigma = self.sigma return 1 + sigmatexp(sigma2t*2/2) sqrt(pi/2) * (erf(sigmat/sqrt(2)) + 1) def Rayleigh(name, sigma): r""" Create a continuous random variable with a Rayleigh distribution. The density of the Rayleigh distribution is given by .. math :: f(x) := \frac{x}{\sigma^2} e^{-x^2/2\sigma^2} with :math:`x > 0`. Parameters ========== sigma : Real number, `\sigma > 0` Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Rayleigh, density, E, variance >>> from sympy import Symbol, simplify >>> sigma = Symbol("sigma", positive=True) >>> z = Symbol("z") >>> X = Rayleigh("x", sigma) >>> density(X)(z) zexp(-z*2/(2sigma2))/sigma2 >>> E(X) sqrt(2)sqrt(pi)sigma/2 >>> variance(X) -pisigma2/2 + 2sigma*2 References ========== .. [1] https://en.wikipedia.org/wiki/Rayleigh_distribution .. [2] http://mathworld.wolfram.com/RayleighDistribution.html """ return rv(name, RayleighDistribution, (sigma, )) #------------------------------------------------------------------------------- # Shifted Gompertz distribution ------------------------------------------------ class ShiftedGompertzDistribution(SingleContinuousDistribution): _argnames = ('b', 'eta') set = Interval(0, oo) @staticmethod def check(b, eta): _value_check(b > 0, "b must be positive") _value_check(eta > 0, "eta must be positive") def pdf(self, x): b, eta = self.b, self.eta return bexp(-bx)exp(-etaexp(-bx))(1+eta(1-exp(-bx))) def ShiftedGompertz(name, b, eta): r""" Create a continuous random variable with a Shifted Gompertz distribution. The density of the Shifted Gompertz distribution is given by .. math:: f(x) := b e^{-b x} e^{-\eta \exp(-b x)} \left[1 + \eta(1 - e^(-bx)) \right] with :math: 'x \in [0, \inf)'. Parameters ========== b: Real number, 'b > 0' a scale eta: Real number, 'eta > 0' a shape Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import ShiftedGompertz, density, E, variance >>> from sympy import Symbol >>> b = Symbol("b", positive=True) >>> eta = Symbol("eta", positive=True) >>> x = Symbol("x") >>> X = ShiftedGompertz("x", b, eta) >>> density(X)(x) b(eta(1 - exp(-bx)) + 1)exp(-bx)exp(-etaexp(-bx)) References ========== .. [1] https://en.wikipedia.org/wiki/Shifted_Gompertz_distribution """ return rv(name, ShiftedGompertzDistribution, (b, eta)) #------------------------------------------------------------------------------- # StudentT distribution -------------------------------------------------------- class StudentTDistribution(SingleContinuousDistribution): _argnames = ('nu',) def pdf(self, x): nu = self.nu return 1/(sqrt(nu)beta_fn(S(1)/2, nu/2))(1 + x2/nu)(-(nu + 1)/2) def _cdf(self, x): nu = self.nu return S.Half + xgamma((nu+1)/2)hyper((S.Half, (nu+1)/2), (S(3)/2,), -x2/nu)/(sqrt(pinu)gamma(nu/2)) def _moment_generating_function(self, t): raise NotImplementedError('The moment generating function for the Student-T distribution is undefined.') def StudentT(name, nu): r""" Create a continuous random variable with a student's t distribution. The density of the student's t distribution is given by .. math:: f(x) := \frac{\Gamma \left(\frac{\nu+1}{2} \right)} {\sqrt{\nu\pi}\Gamma \left(\frac{\nu}{2} \right)} \left(1+\frac{x^2}{\nu} \right)^{-\frac{\nu+1}{2}} Parameters ========== nu : Real number, `\nu > 0`, the degrees of freedom Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import StudentT, density, E, variance, cdf >>> from sympy import Symbol, simplify, pprint >>> nu = Symbol("nu", positive=True) >>> z = Symbol("z") >>> X = StudentT("x", nu) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) nu 1 - -- - - 2 2 / 2\ \| z \| \|1 + --\| \ nu/ ----------------- ____ / nu\ \/ nu B\|1/2, --\| \ 2 / >>> cdf(X)(z) 1/2 + zgamma(nu/2 + 1/2)hyper((1/2, nu/2 + 1/2), (3/2,), -z*2/nu)/(sqrt(pi)sqrt(nu)gamma(nu/2)) References ========== .. [1] https://en.wikipedia.org/wiki/Student_t-distribution .. [2] http://mathworld.wolfram.com/Studentst-Distribution.html """ return rv(name, StudentTDistribution, (nu, )) #------------------------------------------------------------------------------- # Trapezoidal distribution ------------------------------------------------------ class TrapezoidalDistribution(SingleContinuousDistribution): _argnames = ('a', 'b', 'c', 'd') def pdf(self, x): a, b, c, d = self.a, self.b, self.c, self.d return Piecewise( (2(x-a) / ((b-a)(d+c-a-b)), And(a <= x, x < b)), (2 / (d+c-a-b), And(b <= x, x < c)), (2(d-x) / ((d-c)(d+c-a-b)), And(c <= x, x <= d)), (S.Zero, True)) def Trapezoidal(name, a, b, c, d): r""" Create a continuous random variable with a trapezoidal distribution. The density of the trapezoidal distribution is given by .. math:: f(x) := \begin{cases} 0 & \mathrm{for\ } x < a, \\ \frac{2(x-a)}{(b-a)(d+c-a-b)} & \mathrm{for\ } a \le x < b, \\ \frac{2}{d+c-a-b} & \mathrm{for\ } b \le x < c, \\ \frac{2(d-x)}{(d-c)(d+c-a-b)} & \mathrm{for\ } c \le x < d, \\ 0 & \mathrm{for\ } d < x. \end{cases} Parameters ========== a : Real number, :math:`a < d` b : Real number, :math:`a <= b < c` c : Real number, :math:`b < c <= d` d : Real number Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Trapezoidal, density, E >>> from sympy import Symbol, pprint >>> a = Symbol("a") >>> b = Symbol("b") >>> c = Symbol("c") >>> d = Symbol("d") >>> z = Symbol("z") >>> X = Trapezoidal("x", a,b,c,d) >>> pprint(density(X)(z), use_unicode=False) / -2a + 2z \|------------------------- for And(a <= z, b > z) \|(-a + b)(-a - b + c + d) \| \| 2 \| -------------- for And(b <= z, c > z) < -a - b + c + d \| \| 2d - 2z \|------------------------- for And(d >= z, c <= z) \|(-c + d)(-a - b + c + d) \| \ 0 otherwise References ========== .. [1] https://en.wikipedia.org/wiki/Trapezoidal_distribution """ return rv(name, TrapezoidalDistribution, (a, b, c, d)) #------------------------------------------------------------------------------- # Triangular distribution ------------------------------------------------------ class TriangularDistribution(SingleContinuousDistribution): _argnames = ('a', 'b', 'c') def pdf(self, x): a, b, c = self.a, self.b, self.c return Piecewise( (2(x - a)/((b - a)(c - a)), And(a <= x, x < c)), (2/(b - a), Eq(x, c)), (2(b - x)/((b - a)(b - c)), And(c < x, x <= b)), (S.Zero, True)) def _characteristic_function(self, t): a, b, c = self.a, self.b, self.c return -2 ((b-c) * exp(Iat) - (b-a) * exp(Ict) + (c-a) * exp(Ibt)) / ((b-a)(c-a)(b-c)t2) def _moment_generating_function(self, t): a, b, c = self.a, self.b, self.c return 2 ((b - c) * exp(a * t) - (b - a) * exp(c * t) + (c + a) * exp(b * t)) / ( (b - a) * (c - a) * (b - c) * t ** 2) def Triangular(name, a, b, c): r""" Create a continuous random variable with a triangular distribution. The density of the triangular distribution is given by .. math:: f(x) := \begin{cases} 0 & \mathrm{for\ } x < a, \\ \frac{2(x-a)}{(b-a)(c-a)} & \mathrm{for\ } a \le x < c, \\ \frac{2}{b-a} & \mathrm{for\ } x = c, \\ \frac{2(b-x)}{(b-a)(b-c)} & \mathrm{for\ } c < x \le b, \\ 0 & \mathrm{for\ } b < x. \end{cases} Parameters ========== a : Real number, :math:`a \in \left(-\infty, \infty\right)` b : Real number, :math:`a < b` c : Real number, :math:`a \leq c \leq b` Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Triangular, density, E >>> from sympy import Symbol, pprint >>> a = Symbol("a") >>> b = Symbol("b") >>> c = Symbol("c") >>> z = Symbol("z") >>> X = Triangular("x", a,b,c) >>> pprint(density(X)(z), use_unicode=False) / -2a + 2z \|----------------- for And(a <= z, c > z) \|(-a + b)(-a + c) \| \| 2 \| ------ for c = z < -a + b \| \| 2b - 2z \|---------------- for And(b >= z, c < z) \|(-a + b)(b - c) \| \ 0 otherwise References ========== .. [1] https://en.wikipedia.org/wiki/Triangular_distribution .. [2] http://mathworld.wolfram.com/TriangularDistribution.html """ return rv(name, TriangularDistribution, (a, b, c)) #------------------------------------------------------------------------------- # Uniform distribution --------------------------------------------------------- class UniformDistribution(SingleContinuousDistribution): _argnames = ('left', 'right') def pdf(self, x): left, right = self.left, self.right return Piecewise( (S.One/(right - left), And(left <= x, x <= right)), (S.Zero, True) ) def _cdf(self, x): left, right = self.left, self.right return Piecewise( (S.Zero, x < left), ((x - left)/(right - left), x <= right), (S.One, True) ) def _characteristic_function(self, t): left, right = self.left, self.right return Piecewise(((exp(Itright) - exp(Itleft)) / (It(right - left)), Ne(t, 0)), (S.One, True)) def _moment_generating_function(self, t): left, right = self.left, self.right return Piecewise(((exp(tright) - exp(tleft)) / (t * (right - left)), Ne(t, 0)), (S.One, True)) def expectation(self, expr, var, kwargs): from sympy import Max, Min kwargs['evaluate'] = True result = SingleContinuousDistribution.expectation(self, expr, var, kwargs) result = result.subs({Max(self.left, self.right): self.right, Min(self.left, self.right): self.left}) return result def sample(self): return random.uniform(self.left, self.right) def Uniform(name, left, right): r""" Create a continuous random variable with a uniform distribution. The density of the uniform distribution is given by .. math:: f(x) := \begin{cases} \frac{1}{b - a} & \text{for } x \in [a,b] \\ 0 & \text{otherwise} \end{cases} with :math:`x \in [a,b]`. Parameters ========== a : Real number, :math:`-\infty < a` the left boundary b : Real number, :math:`a < b < \infty` the right boundary Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Uniform, density, cdf, E, variance, skewness >>> from sympy import Symbol, simplify >>> a = Symbol("a", negative=True) >>> b = Symbol("b", positive=True) >>> z = Symbol("z") >>> X = Uniform("x", a, b) >>> density(X)(z) Piecewise((1/(-a + b), (b >= z) & (a <= z)), (0, True)) >>> cdf(X)(z) # doctest: +SKIP -a/(-a + b) + z/(-a + b) >>> simplify(E(X)) a/2 + b/2 >>> simplify(variance(X)) a*2/12 - ab/6 + b*2/12 References ========== .. [1] https://en.wikipedia.org/wiki/Uniform_distribution_%28continuous%29 .. [2] http://mathworld.wolfram.com/UniformDistribution.html """ return rv(name, UniformDistribution, (left, right)) #------------------------------------------------------------------------------- # UniformSum distribution ------------------------------------------------------ class UniformSumDistribution(SingleContinuousDistribution): _argnames = ('n',) @property def set(self): return Interval(0, self.n) def pdf(self, x): n = self.n k = Dummy("k") return 1/factorial( n - 1)Sum((-1)*kbinomial(n, k)(x - k)(n - 1), (k, 0, floor(x))) def _cdf(self, x): n = self.n k = Dummy("k") return Piecewise((S.Zero, x < 0), (1/factorial(n)Sum((-1)*kbinomial(n, k)(x - k)(n), (k, 0, floor(x))), x <= n), (S.One, True)) def _characteristic_function(self, t): return ((exp(It) - 1) / (It))self.n def _moment_generating_function(self, t): return ((exp(t) - 1) / t)self.n def UniformSum(name, n): r""" Create a continuous random variable with an Irwin-Hall distribution. The probability distribution function depends on a single parameter `n` which is an integer. The density of the Irwin-Hall distribution is given by .. math :: f(x) := \frac{1}{(n-1)!}\sum_{k=0}^{\left\lfloor x\right\rfloor}(-1)^k \binom{n}{k}(x-k)^{n-1} Parameters ========== n : A positive Integer, `n > 0` Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import UniformSum, density, cdf >>> from sympy import Symbol, pprint >>> n = Symbol("n", integer=True) >>> z = Symbol("z") >>> X = UniformSum("x", n) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) floor(z) ___ \ ` \ k n - 1 /n\ ) (-1) (-k + z) \| \| / \k/ /__, k = 0 -------------------------------- (n - 1)! >>> cdf(X)(z) Piecewise((0, z < 0), (Sum((-1)_k(-_k + z)*nbinomial(n, _k), (_k, 0, floor(z)))/factorial(n), n >= z), (1, True)) Compute cdf with specific 'x' and 'n' values as follows : >>> cdf(UniformSum("x", 5), evaluate=False)(2).doit() 9/40 The argument evaluate=False prevents an attempt at evaluation of the sum for general n, before the argument 2 is passed. References ========== .. [1] https://en.wikipedia.org/wiki/Uniform_sum_distribution .. [2] http://mathworld.wolfram.com/UniformSumDistribution.html """ return rv(name, UniformSumDistribution, (n, )) #------------------------------------------------------------------------------- # VonMises distribution -------------------------------------------------------- class VonMisesDistribution(SingleContinuousDistribution): _argnames = ('mu', 'k') set = Interval(0, 2pi) @staticmethod def check(mu, k): _value_check(k > 0, "k must be positive") def pdf(self, x): mu, k = self.mu, self.k return exp(kcos(x-mu)) / (2pibesseli(0, k)) def VonMises(name, mu, k): r""" Create a Continuous Random Variable with a von Mises distribution. The density of the von Mises distribution is given by .. math:: f(x) := \frac{e^{\kappa\cos(x-\mu)}}{2\pi I_0(\kappa)} with :math:`x \in [0,2\pi]`. Parameters ========== mu : Real number, measure of location k : Real number, measure of concentration Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import VonMises, density, E, variance >>> from sympy import Symbol, simplify, pprint >>> mu = Symbol("mu") >>> k = Symbol("k", positive=True) >>> z = Symbol("z") >>> X = VonMises("x", mu, k) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) kcos(mu - z) e ------------------ 2pibesseli(0, k) References ========== .. [1] https://en.wikipedia.org/wiki/Von_Mises_distribution .. [2] http://mathworld.wolfram.com/vonMisesDistribution.html """ return rv(name, VonMisesDistribution, (mu, k)) #------------------------------------------------------------------------------- # Weibull distribution --------------------------------------------------------- class WeibullDistribution(SingleContinuousDistribution): _argnames = ('alpha', 'beta') set = Interval(0, oo) @staticmethod def check(alpha, beta): _value_check(alpha > 0, "Alpha must be positive") _value_check(beta > 0, "Beta must be positive") def pdf(self, x): alpha, beta = self.alpha, self.beta return beta (x/alpha)*(beta - 1) exp(-(x/alpha)*beta) / alpha def sample(self): return random.weibullvariate(self.alpha, self.beta) def Weibull(name, alpha, beta): r""" Create a continuous random variable with a Weibull distribution. The density of the Weibull distribution is given by .. math:: f(x) := \begin{cases} \frac{k}{\lambda}\left(\frac{x}{\lambda}\right)^{k-1} e^{-(x/\lambda)^{k}} & x\geq0\\ 0 & x<0 \end{cases} Parameters ========== lambda : Real number, :math:`\lambda > 0` a scale k : Real number, `k > 0` a shape Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Weibull, density, E, variance >>> from sympy import Symbol, simplify >>> l = Symbol("lambda", positive=True) >>> k = Symbol("k", positive=True) >>> z = Symbol("z") >>> X = Weibull("x", l, k) >>> density(X)(z) k(z/lambda)*(k - 1)exp(-(z/lambda)*k)/lambda >>> simplify(E(X)) lambdagamma(1 + 1/k) >>> simplify(variance(X)) lambda*2(-gamma(1 + 1/k)*2 + gamma(1 + 2/k)) References ========== .. [1] https://en.wikipedia.org/wiki/Weibull_distribution .. [2] http://mathworld.wolfram.com/WeibullDistribution.html """ return rv(name, WeibullDistribution, (alpha, beta)) #------------------------------------------------------------------------------- # Wigner semicircle distribution ----------------------------------------------- class WignerSemicircleDistribution(SingleContinuousDistribution): _argnames = ('R',) @property def set(self): return Interval(-self.R, self.R) def pdf(self, x): R = self.R return 2/(piR*2)sqrt(R2 - x2) def _characteristic_function(self, t): return Piecewise((2 * besselj(1, self.Rt) / (self.Rt), Ne(t, 0)), (S.One, True)) def _moment_generating_function(self, t): return Piecewise((2 * besseli(1, self.Rt) / (self.Rt), Ne(t, 0)), (S.One, True)) def WignerSemicircle(name, R): r""" Create a continuous random variable with a Wigner semicircle distribution. The density of the Wigner semicircle distribution is given by .. math:: f(x) := \frac2{\pi R^2}\,\sqrt{R^2-x^2} with :math:`x \in [-R,R]`. Parameters ========== R : Real number, `R > 0`, the radius Returns ======= A `RandomSymbol`. Examples ======== >>> from sympy.stats import WignerSemicircle, density, E >>> from sympy import Symbol, simplify >>> R = Symbol("R", positive=True) >>> z = Symbol("z") >>> X = WignerSemicircle("x", R) >>> density(X)(z) 2sqrt(R2 - z2)/(piR**2) >>> E(X) 0 References ========== .. [1] https://en.wikipedia.org/wiki/Wigner_semicircle_distribution .. [2] http://mathworld.wolfram.com/WignersSemicircleLaw.html """ return rv(name, WignerSemicircleDistribution, (R,))
81f2c15ccae4d2bee64ba2063e2bfe3a16c56fc1cc043f55d4fc3250f5aa9ae3	# -- coding: utf-8 -- from __future__ import print_function, division from sympy.core.basic import Basic from sympy.core.compatibility import is_sequence, as_int, string_types from sympy.core.expr import Expr from sympy.core.symbol import Symbol, symbols as _symbols from sympy.core.sympify import CantSympify from sympy.core import S from sympy.printing.defaults import DefaultPrinting from sympy.utilities import public from sympy.utilities.iterables import flatten from sympy.utilities.magic import pollute from sympy import sign @public def free_group(symbols): """Construct a free group returning ``(FreeGroup, (f_0, f_1, ..., f_(n-1))``. Parameters ---------- symbols : str, Symbol/Expr or sequence of str, Symbol/Expr (may be empty) Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> F, x, y, z = free_group("x, y, z") >>> F <free group on the generators (x, y, z)> >>> x*2y-1 x2y-1 >>> type(_) <class 'sympy.combinatorics.free_groups.FreeGroupElement'> """ _free_group = FreeGroup(symbols) return (_free_group,) + tuple(_free_group.generators) @public def xfree_group(symbols): """Construct a free group returning ``(FreeGroup, (f_0, f_1, ..., f_(n-1)))``. Parameters ---------- symbols : str, Symbol/Expr or sequence of str, Symbol/Expr (may be empty) Examples ======== >>> from sympy.combinatorics.free_groups import xfree_group >>> F, (x, y, z) = xfree_group("x, y, z") >>> F <free group on the generators (x, y, z)> >>> y2x*-2z-1 y2x-2z-1 >>> type(_) <class 'sympy.combinatorics.free_groups.FreeGroupElement'> """ _free_group = FreeGroup(symbols) return (_free_group, _free_group.generators) @public def vfree_group(symbols): """Construct a free group and inject ``f_0, f_1, ..., f_(n-1)`` as symbols into the global namespace. Parameters ---------- symbols : str, Symbol/Expr or sequence of str, Symbol/Expr (may be empty) Examples ======== >>> from sympy.combinatorics.free_groups import vfree_group >>> vfree_group("x, y, z") <free group on the generators (x, y, z)> >>> x2y-2z x*2y*-2z >>> type(_) <class 'sympy.combinatorics.free_groups.FreeGroupElement'> """ _free_group = FreeGroup(symbols) pollute([sym.name for sym in _free_group.symbols], _free_group.generators) return _free_group def _parse_symbols(symbols): if not symbols: return tuple() if isinstance(symbols, string_types): return _symbols(symbols, seq=True) elif isinstance(symbols, Expr or FreeGroupElement): return (symbols,) elif is_sequence(symbols): if all(isinstance(s, string_types) for s in symbols): return _symbols(symbols) elif all(isinstance(s, Expr) for s in symbols): return symbols raise ValueError("The type of `symbols` must be one of the following: " "a str, Symbol/Expr or a sequence of " "one of these types") ############################################################################## # FREE GROUP # ############################################################################## _free_group_cache = {} class FreeGroup(DefaultPrinting): """ Free group with finite or infinite number of generators. Its input API is that of a str, Symbol/Expr or a sequence of one of these types (which may be empty) References ========== [1] http://www.gap-system.org/Manuals/doc/ref/chap37.html [2] https://en.wikipedia.org/wiki/Free_group See Also ======== sympy.polys.rings.PolyRing """ is_associative = True is_group = True is_FreeGroup = True is_PermutationGroup = False relators = tuple() def __new__(cls, symbols): symbols = tuple(_parse_symbols(symbols)) rank = len(symbols) _hash = hash((cls.__name__, symbols, rank)) obj = _free_group_cache.get(_hash) if obj is None: obj = object.__new__(cls) obj._hash = _hash obj._rank = rank # dtype method is used to create new instances of FreeGroupElement obj.dtype = type("FreeGroupElement", (FreeGroupElement,), {"group": obj}) obj.symbols = symbols obj.generators = obj._generators() obj._gens_set = set(obj.generators) for symbol, generator in zip(obj.symbols, obj.generators): if isinstance(symbol, Symbol): name = symbol.name if hasattr(obj, name): setattr(obj, name, generator) _free_group_cache[_hash] = obj return obj def _generators(group): """Returns the generators of the FreeGroup. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> F, x, y, z = free_group("x, y, z") >>> F.generators (x, y, z) """ gens = [] for sym in group.symbols: elm = ((sym, 1),) gens.append(group.dtype(elm)) return tuple(gens) def clone(self, symbols=None): return self.__class__(symbols or self.symbols) def __contains__(self, i): """Return True if ``i`` is contained in FreeGroup.""" if not isinstance(i, FreeGroupElement): return False group = i.group return self == group def __hash__(self): return self._hash def __len__(self): return self.rank def __str__(self): if self.rank > 30: str_form = "<free group with %s generators>" % self.rank else: str_form = "<free group on the generators " gens = self.generators str_form += str(gens) + ">" return str_form __repr__ = __str__ def __getitem__(self, index): symbols = self.symbols[index] return self.clone(symbols=symbols) def __eq__(self, other): """No ``FreeGroup`` is equal to any "other" ``FreeGroup``. """ return self is other def index(self, gen): """Return the index of the generator `gen` from ``(f_0, ..., f_(n-1))``. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> F, x, y = free_group("x, y") >>> F.index(y) 1 >>> F.index(x) 0 """ if isinstance(gen, self.dtype): return self.generators.index(gen) else: raise ValueError("expected a generator of Free Group %s, got %s" % (self, gen)) def order(self): """Return the order of the free group. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> F, x, y = free_group("x, y") >>> F.order() oo >>> free_group("")[0].order() 1 """ if self.rank == 0: return 1 else: return S.Infinity @property def elements(self): """ Return the elements of the free group. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> (z,) = free_group("") >>> z.elements {<identity>} """ if self.rank == 0: # A set containing Identity element of `FreeGroup` self is returned return {self.identity} else: raise ValueError("Group contains infinitely many elements" ", hence can't be represented") @property def rank(self): r""" In group theory, the `rank` of a group `G`, denoted `G.rank`, can refer to the smallest cardinality of a generating set for G, that is \operatorname{rank}(G)=\min\{ \|X\|: X\subseteq G, \left\langle X\right\rangle =G\}. """ return self._rank @property def is_abelian(self): """Returns if the group is Abelian. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, x, y, z = free_group("x y z") >>> f.is_abelian False """ if self.rank == 0 or self.rank == 1: return True else: return False @property def identity(self): """Returns the identity element of free group.""" return self.dtype() def contains(self, g): """Tests if Free Group element ``g`` belong to self, ``G``. In mathematical terms any linear combination of generators of a Free Group is contained in it. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, x, y, z = free_group("x y z") >>> f.contains(x*3y*2) True """ if not isinstance(g, FreeGroupElement): return False elif self != g.group: return False else: return True def center(self): """Returns the center of the free group `self`.""" return {self.identity} ############################################################################ # FreeGroupElement # ############################################################################ class FreeGroupElement(CantSympify, DefaultPrinting, tuple): """Used to create elements of FreeGroup. It can not be used directly to create a free group element. It is called by the `dtype` method of the `FreeGroup` class. """ is_assoc_word = True def new(self, init): return self.__class__(init) _hash = None def __hash__(self): _hash = self._hash if _hash is None: self._hash = _hash = hash((self.group, frozenset(tuple(self)))) return _hash def copy(self): return self.new(self) @property def is_identity(self): if self.array_form == tuple(): return True else: return False @property def array_form(self): """ SymPy provides two different internal kinds of representation of associative words. The first one is called the `array_form` which is a tuple containing `tuples` as its elements, where the size of each tuple is two. At the first position the tuple contains the `symbol-generator`, while at the second position of tuple contains the exponent of that generator at the position. Since elements (i.e. words) don't commute, the indexing of tuple makes that property to stay. The structure in ``array_form`` of ``FreeGroupElement`` is of form: ``( ( symbol_of_gen , exponent ), ( , ), ... ( , ) )`` Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, x, y, z = free_group("x y z") >>> (xz).array_form ((x, 1), (z, 1)) >>> (x*2zyx2).array_form ((x, 2), (z, 1), (y, 1), (x, 2)) See Also ======== letter_repr """ return tuple(self) @property def letter_form(self): """ The letter representation of a ``FreeGroupElement`` is a tuple of generator symbols, with each entry corresponding to a group generator. Inverses of the generators are represented by negative generator symbols. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, a, b, c, d = free_group("a b c d") >>> (a3).letter_form (a, a, a) >>> (a*2d*-2ab-4).letter_form (a, a, -d, -d, a, -b, -b, -b, -b) >>> (a-2b*3d).letter_form (-a, -a, b, b, b, d) See Also ======== array_form """ return tuple(flatten([(i,)j if j > 0 else (-i,)(-j) for i, j in self.array_form])) def __getitem__(self, i): group = self.group r = self.letter_form[i] if r.is_Symbol: return group.dtype(((r, 1),)) else: return group.dtype(((-r, -1),)) def index(self, gen): if len(gen) != 1: raise ValueError() return (self.letter_form).index(gen.letter_form[0]) @property def letter_form_elm(self): """ """ group = self.group r = self.letter_form return [group.dtype(((elm,1),)) if elm.is_Symbol \ else group.dtype(((-elm,-1),)) for elm in r] @property def ext_rep(self): """This is called the External Representation of ``FreeGroupElement`` """ return tuple(flatten(self.array_form)) def __contains__(self, gen): return gen.array_form[0][0] in tuple([r[0] for r in self.array_form]) def __str__(self): if self.is_identity: return "<identity>" symbols = self.group.symbols str_form = "" array_form = self.array_form for i in range(len(array_form)): if i == len(array_form) - 1: if array_form[i][1] == 1: str_form += str(array_form[i][0]) else: str_form += str(array_form[i][0]) + \ "*" + str(array_form[i][1]) else: if array_form[i][1] == 1: str_form += str(array_form[i][0]) + "" else: str_form += str(array_form[i][0]) + \ "*" + str(array_form[i][1]) + "" return str_form __repr__ = __str__ def __pow__(self, n): n = as_int(n) group = self.group if n == 0: return group.identity if n < 0: n = -n return (self.inverse())*n result = self for i in range(n - 1): result = resultself # this method can be improved instead of just returning the # multiplication of elements return result def __mul__(self, other): """Returns the product of elements belonging to the same ``FreeGroup``. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, x, y, z = free_group("x y z") >>> xy2y*-4 xy*-2 >>> zy*-2 zy-2 >>> x2yy*-1x*-2 <identity> """ group = self.group if not isinstance(other, group.dtype): raise TypeError("only FreeGroup elements of same FreeGroup can " "be multiplied") if self.is_identity: return other if other.is_identity: return self r = list(self.array_form + other.array_form) zero_mul_simp(r, len(self.array_form) - 1) return group.dtype(tuple(r)) def __div__(self, other): group = self.group if not isinstance(other, group.dtype): raise TypeError("only FreeGroup elements of same FreeGroup can " "be multiplied") return self(other.inverse()) def __rdiv__(self, other): group = self.group if not isinstance(other, group.dtype): raise TypeError("only FreeGroup elements of same FreeGroup can " "be multiplied") return other(self.inverse()) __truediv__ = __div__ __rtruediv__ = __rdiv__ def __add__(self, other): return NotImplemented def inverse(self): """ Returns the inverse of a ``FreeGroupElement`` element Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, x, y, z = free_group("x y z") >>> x.inverse() x-1 >>> (xy).inverse() y*-1x-1 """ group = self.group r = tuple([(i, -j) for i, j in self.array_form[::-1]]) return group.dtype(r) def order(self): """Find the order of a ``FreeGroupElement``. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, x, y = free_group("x y") >>> (x2yy*-1x*-2).order() 1 """ if self.is_identity: return 1 else: return S.Infinity def commutator(self, other): """ Return the commutator of `self` and `x`: ``~x~selfxself`` """ group = self.group if not isinstance(other, group.dtype): raise ValueError("commutator of only FreeGroupElement of the same " "FreeGroup exists") else: return self.inverse()other.inverse()selfother def eliminate_words(self, words, _all=False, inverse=True): ''' Replace each subword from the dictionary `words` by words[subword]. If words is a list, replace the words by the identity. ''' again = True new = self if isinstance(words, dict): while again: again = False for sub in words: prev = new new = new.eliminate_word(sub, words[sub], _all=_all, inverse=inverse) if new != prev: again = True else: while again: again = False for sub in words: prev = new new = new.eliminate_word(sub, _all=_all, inverse=inverse) if new != prev: again = True return new def eliminate_word(self, gen, by=None, _all=False, inverse=True): """ For an associative word `self`, a subword `gen`, and an associative word `by` (identity by default), return the associative word obtained by replacing each occurrence of `gen` in `self` by `by`. If `_all = True`, the occurrences of `gen` that may appear after the first substitution will also be replaced and so on until no occurrences are found. This might not always terminate (e.g. `(x).eliminate_word(x, x2, _all=True)`). Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, x, y = free_group("x y") >>> w = x5yx2y*-4x >>> w.eliminate_word( x, x2 ) x10yx*4y*-4x2 >>> w.eliminate_word( x, y-1 ) y-11 >>> w.eliminate_word(x5) yx2y*-4x >>> w.eliminate_word(xy, y) x4yx2y*-4x See Also ======== substituted_word """ if by == None: by = self.group.identity if self.is_independent(gen) or gen == by: return self if gen == self: return by if gen-1 == by: _all = False word = self l = len(gen) try: i = word.subword_index(gen) k = 1 except ValueError: if not inverse: return word try: i = word.subword_index(gen-1) k = -1 except ValueError: return word word = word.subword(0, i)bykword.subword(i+l, len(word)).eliminate_word(gen, by) if _all: return word.eliminate_word(gen, by, _all=True, inverse=inverse) else: return word def __len__(self): """ For an associative word `self`, returns the number of letters in it. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, a, b = free_group("a b") >>> w = a*5ba2b*-4a >>> len(w) 13 >>> len(a17) 17 >>> len(w0) 0 """ return sum(abs(j) for (i, j) in self) def __eq__(self, other): """ Two associative words are equal if they are words over the same alphabet and if they are sequences of the same letters. This is equivalent to saying that the external representations of the words are equal. There is no "universal" empty word, every alphabet has its own empty word. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, swapnil0, swapnil1 = free_group("swapnil0 swapnil1") >>> f <free group on the generators (swapnil0, swapnil1)> >>> g, swap0, swap1 = free_group("swap0 swap1") >>> g <free group on the generators (swap0, swap1)> >>> swapnil0 == swapnil1 False >>> swapnil0swapnil1 == swapnil1/swapnil1swapnil0swapnil1 True >>> swapnil0swapnil1 == swapnil1swapnil0 False >>> swapnil10 == swap00 False """ group = self.group if not isinstance(other, group.dtype): return False return tuple.__eq__(self, other) def __lt__(self, other): """ The ordering of associative words is defined by length and lexicography (this ordering is called short-lex ordering), that is, shorter words are smaller than longer words, and words of the same length are compared w.r.t. the lexicographical ordering induced by the ordering of generators. Generators are sorted according to the order in which they were created. If the generators are invertible then each generator `g` is larger than its inverse `g^{-1}`, and `g^{-1}` is larger than every generator that is smaller than `g`. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, a, b = free_group("a b") >>> b < a False >>> a < a.inverse() False """ group = self.group if not isinstance(other, group.dtype): raise TypeError("only FreeGroup elements of same FreeGroup can " "be compared") l = len(self) m = len(other) # implement lenlex order if l < m: return True elif l > m: return False for i in range(l): a = self[i].array_form[0] b = other[i].array_form[0] p = group.symbols.index(a[0]) q = group.symbols.index(b[0]) if p < q: return True elif p > q: return False elif a[1] < b[1]: return True elif a[1] > b[1]: return False return False def __le__(self, other): return (self == other or self < other) def __gt__(self, other): """ Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, x, y, z = free_group("x y z") >>> y2 > x2 True >>> yz > zy False >>> x > x.inverse() True """ group = self.group if not isinstance(other, group.dtype): raise TypeError("only FreeGroup elements of same FreeGroup can " "be compared") return not self <= other def __ge__(self, other): return not self < other def exponent_sum(self, gen): """ For an associative word `self` and a generator or inverse of generator `gen`, ``exponent_sum`` returns the number of times `gen` appears in `self` minus the number of times its inverse appears in `self`. If neither `gen` nor its inverse occur in `self` then 0 is returned. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> F, x, y = free_group("x, y") >>> w = x2y3 >>> w.exponent_sum(x) 2 >>> w.exponent_sum(x-1) -2 >>> w = x*2y*4x*-3 >>> w.exponent_sum(x) -1 See Also ======== generator_count """ if len(gen) != 1: raise ValueError("gen must be a generator or inverse of a generator") s = gen.array_form[0] return s[1]sum([i[1] for i in self.array_form if i[0] == s[0]]) def generator_count(self, gen): """ For an associative word `self` and a generator `gen`, ``generator_count`` returns the multiplicity of generator `gen` in `self`. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> F, x, y = free_group("x, y") >>> w = x*2y3 >>> w.generator_count(x) 2 >>> w = x2y4x*-3 >>> w.generator_count(x) 5 See Also ======== exponent_sum """ if len(gen) != 1 or gen.array_form[0][1] < 0: raise ValueError("gen must be a generator") s = gen.array_form[0] return s[1]sum([abs(i[1]) for i in self.array_form if i[0] == s[0]]) def subword(self, from_i, to_j, strict=True): """ For an associative word `self` and two positive integers `from_i` and `to_j`, `subword` returns the subword of `self` that begins at position `from_i` and ends at `to_j - 1`, indexing is done with origin 0. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, a, b = free_group("a b") >>> w = a*5ba2b*-4a >>> w.subword(2, 6) a*3b """ group = self.group if not strict: from_i = max(from_i, 0) to_j = min(len(self), to_j) if from_i < 0 or to_j > len(self): raise ValueError("`from_i`, `to_j` must be positive and no greater than " "the length of associative word") if to_j <= from_i: return group.identity else: letter_form = self.letter_form[from_i: to_j] array_form = letter_form_to_array_form(letter_form, group) return group.dtype(array_form) def subword_index(self, word, start = 0): ''' Find the index of `word` in `self`. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, a, b = free_group("a b") >>> w = a*2bab*3 >>> w.subword_index(abab) 1 ''' l = len(word) self_lf = self.letter_form word_lf = word.letter_form index = None for i in range(start,len(self_lf)-l+1): if self_lf[i:i+l] == word_lf: index = i break if index is not None: return index else: raise ValueError("The given word is not a subword of self") def is_dependent(self, word): """ Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> F, x, y = free_group("x, y") >>> (x*4y-3).is_dependent(x4y-2) True >>> (x2y*-1).is_dependent(xy) False >>> (xy2xy2).is_dependent(xy2) True >>> (x12).is_dependent(x-4) True See Also ======== is_independent """ try: return self.subword_index(word) != None except ValueError: pass try: return self.subword_index(word-1) != None except ValueError: return False def is_independent(self, word): """ See Also ======== is_dependent """ return not self.is_dependent(word) def contains_generators(self): """ Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> F, x, y, z = free_group("x, y, z") >>> (x*2y-1).contains_generators() {x, y} >>> (x3z).contains_generators() {x, z} """ group = self.group gens = set() for syllable in self.array_form: gens.add(group.dtype(((syllable[0], 1),))) return set(gens) def cyclic_subword(self, from_i, to_j): group = self.group l = len(self) letter_form = self.letter_form period1 = int(from_i/l) if from_i >= l: from_i -= lperiod1 to_j -= lperiod1 diff = to_j - from_i word = letter_form[from_i: to_j] period2 = int(to_j/l) - 1 word += letter_formperiod2 + letter_form[:diff-l+from_i-lperiod2] word = letter_form_to_array_form(word, group) return group.dtype(word) def cyclic_conjugates(self): """Returns a words which are cyclic to the word `self`. References ========== http://planetmath.org/cyclicpermutation Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> F, x, y = free_group("x, y") >>> w = xyxyx >>> w.cyclic_conjugates() {xyx2y, x*2yxy, yxyx2, yx*2yx, xyxyx} >>> s = xyx2yx >>> s.cyclic_conjugates() {x2yx2y, yx2yx2, xyx2yx} """ return {self.cyclic_subword(i, i+len(self)) for i in range(len(self))} def is_cyclic_conjugate(self, w): """ Checks whether words ``self``, ``w`` are cyclic conjugates. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> F, x, y = free_group("x, y") >>> w1 = x2y*5 >>> w2 = xy*5x >>> w1.is_cyclic_conjugate(w2) True >>> w3 = x*-1y*5x-1 >>> w3.is_cyclic_conjugate(w2) False """ l1 = len(self) l2 = len(w) if l1 != l2: return False w1 = self.identity_cyclic_reduction() w2 = w.identity_cyclic_reduction() letter1 = w1.letter_form letter2 = w2.letter_form str1 = ' '.join(map(str, letter1)) str2 = ' '.join(map(str, letter2)) if len(str1) != len(str2): return False return str1 in str2 + ' ' + str2 def number_syllables(self): """Returns the number of syllables of the associative word `self`. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, swapnil0, swapnil1 = free_group("swapnil0 swapnil1") >>> (swapnil13swapnil0swapnil1-1).number_syllables() 3 """ return len(self.array_form) def exponent_syllable(self, i): """ Returns the exponent of the `i`-th syllable of the associative word `self`. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, a, b = free_group("a b") >>> w = a5ba*2b*-4a >>> w.exponent_syllable( 2 ) 2 """ return self.array_form[i][1] def generator_syllable(self, i): """ Returns the symbol of the generator that is involved in the i-th syllable of the associative word `self`. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, a, b = free_group("a b") >>> w = a*5ba2b*-4a >>> w.generator_syllable( 3 ) b """ return self.array_form[i][0] def sub_syllables(self, from_i, to_j): """ `sub_syllables` returns the subword of the associative word `self` that consists of syllables from positions `from_to` to `to_j`, where `from_to` and `to_j` must be positive integers and indexing is done with origin 0. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, a, b = free_group("a, b") >>> w = a*5ba2b*-4a >>> w.sub_syllables(1, 2) b >>> w.sub_syllables(3, 3) <identity> """ if not isinstance(from_i, int) or not isinstance(to_j, int): raise ValueError("both arguments should be integers") group = self.group if to_j <= from_i: return group.identity else: r = tuple(self.array_form[from_i: to_j]) return group.dtype(r) def substituted_word(self, from_i, to_j, by): """ Returns the associative word obtained by replacing the subword of `self` that begins at position `from_i` and ends at position `to_j - 1` by the associative word `by`. `from_i` and `to_j` must be positive integers, indexing is done with origin 0. In other words, `w.substituted_word(w, from_i, to_j, by)` is the product of the three words: `w.subword(0, from_i)`, `by`, and `w.subword(to_j len(w))`. See Also ======== eliminate_word """ lw = len(self) if from_i >= to_j or from_i > lw or to_j > lw: raise ValueError("values should be within bounds") # otherwise there are four possibilities # first if from=1 and to=lw then if from_i == 0 and to_j == lw: return by elif from_i == 0: # second if from_i=1 (and to_j < lw) then return byself.subword(to_j, lw) elif to_j == lw: # third if to_j=1 (and from_i > 1) then return self.subword(0, from_i)by else: # finally return self.subword(0, from_i)byself.subword(to_j, lw) def is_cyclically_reduced(self): r"""Returns whether the word is cyclically reduced or not. A word is cyclically reduced if by forming the cycle of the word, the word is not reduced, i.e a word w = `a_1 ... a_n` is called cyclically reduced if `a_1 \ne a_n^{−1}`. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> F, x, y = free_group("x, y") >>> (x*2y*-1x*-1).is_cyclically_reduced() False >>> (yx*2y2).is_cyclically_reduced() True """ if not self: return True return self[0] != self[-1]-1 def identity_cyclic_reduction(self): """Return a unique cyclically reduced version of the word. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> F, x, y = free_group("x, y") >>> (x*2y*2x*-1).identity_cyclic_reduction() xy2 >>> (x-3y-1x5).identity_cyclic_reduction() x2y-1 References ========== http://planetmath.org/cyclicallyreduced """ word = self.copy() group = self.group while not word.is_cyclically_reduced(): exp1 = word.exponent_syllable(0) exp2 = word.exponent_syllable(-1) r = exp1 + exp2 if r == 0: rep = word.array_form[1: word.number_syllables() - 1] else: rep = ((word.generator_syllable(0), exp1 + exp2),) + \ word.array_form[1: word.number_syllables() - 1] word = group.dtype(rep) return word def cyclic_reduction(self, removed=False): """Return a cyclically reduced version of the word. Unlike `identity_cyclic_reduction`, this will not cyclically permute the reduced word - just remove the "unreduced" bits on either side of it. Compare the examples with those of `identity_cyclic_reduction`. When `removed` is `True`, return a tuple `(word, r)` where self `r` is such that before the reduction the word was either `rwordr-1`. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> F, x, y = free_group("x, y") >>> (x2y*2x*-1).cyclic_reduction() xy2 >>> (x-3y-1x5).cyclic_reduction() y-1x2 >>> (x-3y*-1x5).cyclic_reduction(removed=True) (y-1x2, x-3) """ word = self.copy() group = self.group g = self.group.identity while not word.is_cyclically_reduced(): exp1 = abs(word.exponent_syllable(0)) exp2 = abs(word.exponent_syllable(-1)) exp = min(exp1, exp2) start = word[0]abs(exp) end = word[-1]abs(exp) word = start-1wordend-1 g = gstart if removed: return word, g return word def power_of(self, other): ''' Check if `self == other*n` for some integer n. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> F, x, y = free_group("x, y") >>> ((xy)*2).power_of(xy) True >>> (x*-3y*-2x3).power_of(x-3yx3) True ''' if self.is_identity: return True l = len(other) if l == 1: # self has to be a power of one generator gens = self.contains_generators() s = other in gens or other-1 in gens return len(gens) == 1 and s # if self is not cyclically reduced and it is a power of other, # other isn't cyclically reduced and the parts removed during # their reduction must be equal reduced, r1 = self.cyclic_reduction(removed=True) if not r1.is_identity: other, r2 = other.cyclic_reduction(removed=True) if r1 == r2: return reduced.power_of(other) return False if len(self) < l or len(self) % l: return False prefix = self.subword(0, l) if prefix == other or prefix**-1 == other: rest = self.subword(l, len(self)) return rest.power_of(other) return False def letter_form_to_array_form(array_form, group): """ This method converts a list given with possible repetitions of elements in it. It returns a new list such that repetitions of consecutive elements is removed and replace with a tuple element of size two such that the first index contains `value` and the second index contains the number of consecutive repetitions of `value`. """ a = list(array_form[:]) new_array = [] n = 1 symbols = group.symbols for i in range(len(a)): if i == len(a) - 1: if a[i] == a[i - 1]: if (-a[i]) in symbols: new_array.append((-a[i], -n)) else: new_array.append((a[i], n)) else: if (-a[i]) in symbols: new_array.append((-a[i], -1)) else: new_array.append((a[i], 1)) return new_array elif a[i] == a[i + 1]: n += 1 else: if (-a[i]) in symbols: new_array.append((-a[i], -n)) else: new_array.append((a[i], n)) n = 1 def zero_mul_simp(l, index): """Used to combine two reduced words.""" while index >=0 and index < len(l) - 1 and l[index][0] == l[index + 1][0]: exp = l[index][1] + l[index + 1][1] base = l[index][0] l[index] = (base, exp) del l[index + 1] if l[index][1] == 0: del l[index] index -= 1
53fbe4d439dffb6950e8094e0d5095d333a54de40db58247d20f932a006be02c	from __future__ import print_function, division from sympy.core.compatibility import range from sympy.core.mul import Mul from sympy.core.singleton import S from sympy.concrete.expr_with_intlimits import ExprWithIntLimits from sympy.core.exprtools import factor_terms from sympy.functions.elementary.exponential import exp, log from sympy.polys import quo, roots from sympy.simplify import powsimp class Product(ExprWithIntLimits): r"""Represents unevaluated products. ``Product`` represents a finite or infinite product, with the first argument being the general form of terms in the series, and the second argument being ``(dummy_variable, start, end)``, with ``dummy_variable`` taking all integer values from ``start`` through ``end``. In accordance with long-standing mathematical convention, the end term is included in the product. Finite products =============== For finite products (and products with symbolic limits assumed to be finite) we follow the analogue of the summation convention described by Karr [1], especially definition 3 of section 1.4. The product: .. math:: \prod_{m \leq i < n} f(i) has the obvious meaning for `m < n`, namely: .. math:: \prod_{m \leq i < n} f(i) = f(m) f(m+1) \cdot \ldots \cdot f(n-2) f(n-1) with the upper limit value `f(n)` excluded. The product over an empty set is one if and only if `m = n`: .. math:: \prod_{m \leq i < n} f(i) = 1 \quad \mathrm{for} \quad m = n Finally, for all other products over empty sets we assume the following definition: .. math:: \prod_{m \leq i < n} f(i) = \frac{1}{\prod_{n \leq i < m} f(i)} \quad \mathrm{for} \quad m > n It is important to note that above we define all products with the upper limit being exclusive. This is in contrast to the usual mathematical notation, but does not affect the product convention. Indeed we have: .. math:: \prod_{m \leq i < n} f(i) = \prod_{i = m}^{n - 1} f(i) where the difference in notation is intentional to emphasize the meaning, with limits typeset on the top being inclusive. Examples ======== >>> from sympy.abc import a, b, i, k, m, n, x >>> from sympy import Product, factorial, oo >>> Product(k, (k, 1, m)) Product(k, (k, 1, m)) >>> Product(k, (k, 1, m)).doit() factorial(m) >>> Product(k2,(k, 1, m)) Product(k2, (k, 1, m)) >>> Product(k2,(k, 1, m)).doit() factorial(m)2 Wallis' product for pi: >>> W = Product(2i/(2i-1) * 2i/(2i+1), (i, 1, oo)) >>> W Product(4i2/((2i - 1)(2i + 1)), (i, 1, oo)) Direct computation currently fails: >>> W.doit() Product(4i2/((2i - 1)(2i + 1)), (i, 1, oo)) But we can approach the infinite product by a limit of finite products: >>> from sympy import limit >>> W2 = Product(2i/(2i-1)2i/(2i+1), (i, 1, n)) >>> W2 Product(4i*2/((2i - 1)(2i + 1)), (i, 1, n)) >>> W2e = W2.doit() >>> W2e 2*(-2n)4nfactorial(n)*2/(RisingFactorial(1/2, n)RisingFactorial(3/2, n)) >>> limit(W2e, n, oo) pi/2 By the same formula we can compute sin(pi/2): >>> from sympy import pi, gamma, simplify >>> P = pi * x * Product(1 - x2/k2, (k, 1, n)) >>> P = P.subs(x, pi/2) >>> P pi*2Product(1 - pi*2/(4k2), (k, 1, n))/2 >>> Pe = P.doit() >>> Pe pi2RisingFactorial(1 + pi/2, n)RisingFactorial(-pi/2 + 1, n)/(2factorial(n)2) >>> Pe = Pe.rewrite(gamma) >>> Pe pi2gamma(n + 1 + pi/2)gamma(n - pi/2 + 1)/(2gamma(1 + pi/2)gamma(-pi/2 + 1)gamma(n + 1)2) >>> Pe = simplify(Pe) >>> Pe sin(pi2/2)gamma(n + 1 + pi/2)gamma(n - pi/2 + 1)/gamma(n + 1)2 >>> limit(Pe, n, oo) sin(pi2/2) Products with the lower limit being larger than the upper one: >>> Product(1/i, (i, 6, 1)).doit() 120 >>> Product(i, (i, 2, 5)).doit() 120 The empty product: >>> Product(i, (i, n, n-1)).doit() 1 An example showing that the symbolic result of a product is still valid for seemingly nonsensical values of the limits. Then the Karr convention allows us to give a perfectly valid interpretation to those products by interchanging the limits according to the above rules: >>> P = Product(2, (i, 10, n)).doit() >>> P 2(n - 9) >>> P.subs(n, 5) 1/16 >>> Product(2, (i, 10, 5)).doit() 1/16 >>> 1/Product(2, (i, 6, 9)).doit() 1/16 An explicit example of the Karr summation convention applied to products: >>> P1 = Product(x, (i, a, b)).doit() >>> P1 x(-a + b + 1) >>> P2 = Product(x, (i, b+1, a-1)).doit() >>> P2 x*(a - b - 1) >>> simplify(P1 P2) 1 And another one: >>> P1 = Product(i, (i, b, a)).doit() >>> P1 RisingFactorial(b, a - b + 1) >>> P2 = Product(i, (i, a+1, b-1)).doit() >>> P2 RisingFactorial(a + 1, -a + b - 1) >>> P1 * P2 RisingFactorial(b, a - b + 1)RisingFactorial(a + 1, -a + b - 1) >>> simplify(P1 P2) 1 See Also ======== Sum, summation product References ========== .. [1] Michael Karr, "Summation in Finite Terms", Journal of the ACM, Volume 28 Issue 2, April 1981, Pages 305-350 http://dl.acm.org/citation.cfm?doid=322248.322255 .. [2] https://en.wikipedia.org/wiki/Multiplication#Capital_Pi_notation .. [3] https://en.wikipedia.org/wiki/Empty_product """ __slots__ = ['is_commutative'] def __new__(cls, function, symbols, assumptions): obj = ExprWithIntLimits.__new__(cls, function, symbols, *assumptions) return obj def _eval_rewrite_as_Sum(self, args, *kwargs): from sympy.concrete.summations import Sum return exp(Sum(log(self.function), self.limits)) @property def term(self): return self._args[0] function = term def _eval_is_zero(self): # a Product is zero only if its term is zero. return self.term.is_zero def doit(self, *hints): f = self.function for index, limit in enumerate(self.limits): i, a, b = limit dif = b - a if dif.is_Integer and dif < 0: a, b = b + 1, a - 1 f = 1 / f g = self._eval_product(f, (i, a, b)) if g in (None, S.NaN): return self.func(powsimp(f), self.limits[index:]) else: f = g if hints.get('deep', True): return f.doit(*hints) else: return powsimp(f) def _eval_adjoint(self): if self.is_commutative: return self.func(self.function.adjoint(), self.limits) return None def _eval_conjugate(self): return self.func(self.function.conjugate(), self.limits) def _eval_product(self, term, limits): from sympy.concrete.delta import deltaproduct, _has_simple_delta from sympy.concrete.summations import summation from sympy.functions import KroneckerDelta, RisingFactorial (k, a, n) = limits if k not in term.free_symbols: if (term - 1).is_zero: return S.One return term(n - a + 1) if a == n: return term.subs(k, a) if term.has(KroneckerDelta) and _has_simple_delta(term, limits[0]): return deltaproduct(term, limits) dif = n - a if dif.is_Integer: return Mul([term.subs(k, a + i) for i in range(dif + 1)]) elif term.is_polynomial(k): poly = term.as_poly(k) A = B = Q = S.One all_roots = roots(poly) M = 0 for r, m in all_roots.items(): M += m A = RisingFactorial(a - r, n - a + 1)m Q = (n - r)m if M < poly.degree(): arg = quo(poly, Q.as_poly(k)) B = self.func(arg, (k, a, n)).doit() return poly.LC()(n - a + 1) * A * B elif term.is_Add: factored = factor_terms(term, fraction=True) if factored.is_Mul: return self._eval_product(factored, (k, a, n)) elif term.is_Mul: exclude, include = [], [] for t in term.args: p = self._eval_product(t, (k, a, n)) if p is not None: exclude.append(p) else: include.append(t) if not exclude: return None else: arg = term._new_rawargs(include) A = Mul(exclude) B = self.func(arg, (k, a, n)).doit() return A * B elif term.is_Pow: if not term.base.has(k): s = summation(term.exp, (k, a, n)) return term.bases elif not term.exp.has(k): p = self._eval_product(term.base, (k, a, n)) if p is not None: return pterm.exp elif isinstance(term, Product): evaluated = term.doit() f = self._eval_product(evaluated, limits) if f is None: return self.func(evaluated, limits) else: return f def _eval_simplify(self, ratio, measure, rational, inverse): from sympy.simplify.simplify import product_simplify return product_simplify(self) def _eval_transpose(self): if self.is_commutative: return self.func(self.function.transpose(), self.limits) return None def is_convergent(self): r""" See docs of Sum.is_convergent() for explanation of convergence in SymPy. The infinite product: .. math:: \prod_{1 \leq i < \infty} f(i) is defined by the sequence of partial products: .. math:: \prod_{i=1}^{n} f(i) = f(1) f(2) \cdots f(n) as n increases without bound. The product converges to a non-zero value if and only if the sum: .. math:: \sum_{1 \leq i < \infty} \log{f(n)} converges. Examples ======== >>> from sympy import Interval, S, Product, Symbol, cos, pi, exp, oo >>> n = Symbol('n', integer=True) >>> Product(n/(n + 1), (n, 1, oo)).is_convergent() False >>> Product(1/n2, (n, 1, oo)).is_convergent() False >>> Product(cos(pi/n), (n, 1, oo)).is_convergent() True >>> Product(exp(-n2), (n, 1, oo)).is_convergent() False References ========== .. [1] https://en.wikipedia.org/wiki/Infinite_product """ from sympy.concrete.summations import Sum sequence_term = self.function log_sum = log(sequence_term) lim = self.limits try: is_conv = Sum(log_sum, lim).is_convergent() except NotImplementedError: if Sum(sequence_term - 1, lim).is_absolutely_convergent() is S.true: return S.true raise NotImplementedError("The algorithm to find the product convergence of %s " "is not yet implemented" % (sequence_term)) return is_conv def reverse_order(expr, indices): """ Reverse the order of a limit in a Product. Usage ===== ``reverse_order(expr, indices)`` reverses some limits in the expression ``expr`` which can be either a ``Sum`` or a ``Product``. The selectors in the argument ``indices`` specify some indices whose limits get reversed. These selectors are either variable names or numerical indices counted starting from the inner-most limit tuple. Examples ======== >>> from sympy import Product, simplify, RisingFactorial, gamma, Sum >>> from sympy.abc import x, y, a, b, c, d >>> P = Product(x, (x, a, b)) >>> Pr = P.reverse_order(x) >>> Pr Product(1/x, (x, b + 1, a - 1)) >>> Pr = Pr.doit() >>> Pr 1/RisingFactorial(b + 1, a - b - 1) >>> simplify(Pr) gamma(b + 1)/gamma(a) >>> P = P.doit() >>> P RisingFactorial(a, -a + b + 1) >>> simplify(P) gamma(b + 1)/gamma(a) While one should prefer variable names when specifying which limits to reverse, the index counting notation comes in handy in case there are several symbols with the same name. >>> S = Sum(xy, (x, a, b), (y, c, d)) >>> S Sum(xy, (x, a, b), (y, c, d)) >>> S0 = S.reverse_order(0) >>> S0 Sum(-xy, (x, b + 1, a - 1), (y, c, d)) >>> S1 = S0.reverse_order(1) >>> S1 Sum(xy, (x, b + 1, a - 1), (y, d + 1, c - 1)) Of course we can mix both notations: >>> Sum(xy, (x, a, b), (y, 2, 5)).reverse_order(x, 1) Sum(xy, (x, b + 1, a - 1), (y, 6, 1)) >>> Sum(xy, (x, a, b), (y, 2, 5)).reverse_order(y, x) Sum(xy, (x, b + 1, a - 1), (y, 6, 1)) See Also ======== index, reorder_limit, reorder References ========== .. [1] Michael Karr, "Summation in Finite Terms", Journal of the ACM, Volume 28 Issue 2, April 1981, Pages 305-350 http://dl.acm.org/citation.cfm?doid=322248.322255 """ l_indices = list(indices) for i, indx in enumerate(l_indices): if not isinstance(indx, int): l_indices[i] = expr.index(indx) e = 1 limits = [] for i, limit in enumerate(expr.limits): l = limit if i in l_indices: e = -e l = (limit[0], limit[2] + 1, limit[1] - 1) limits.append(l) return Product(expr.function * e, limits) def product(args, kwargs): r""" Compute the product. The notation for symbols is similar to the notation used in Sum or Integral. product(f, (i, a, b)) computes the product of f with respect to i from a to b, i.e., :: b _____ product(f(n), (i, a, b)) = \| \| f(n) \| \| i = a If it cannot compute the product, it returns an unevaluated Product object. Repeated products can be computed by introducing additional symbols tuples:: >>> from sympy import product, symbols >>> i, n, m, k = symbols('i n m k', integer=True) >>> product(i, (i, 1, k)) factorial(k) >>> product(m, (i, 1, k)) mk >>> product(i, (i, 1, k), (k, 1, n)) Product(factorial(k), (k, 1, n)) """ prod = Product(args, *kwargs) if isinstance(prod, Product): return prod.doit(deep=False) else: return prod
7b7ec119ea92ce225fdca8ede27acf136610889074379e3c481576e53e09c75f	""" This module implements sums and products containing the Kronecker Delta function. References ========== - http://mathworld.wolfram.com/KroneckerDelta.html """ from __future__ import print_function, division from sympy.core import Add, Mul, S, Dummy from sympy.core.cache import cacheit from sympy.core.compatibility import default_sort_key, range from sympy.functions import KroneckerDelta, Piecewise, piecewise_fold from sympy.sets import Interval @cacheit def _expand_delta(expr, index): """ Expand the first Add containing a simple KroneckerDelta. """ if not expr.is_Mul: return expr delta = None func = Add terms = [S(1)] for h in expr.args: if delta is None and h.is_Add and _has_simple_delta(h, index): delta = True func = h.func terms = [terms[0]t for t in h.args] else: terms = [th for t in terms] return func(terms) @cacheit def _extract_delta(expr, index): """ Extract a simple KroneckerDelta from the expression. Returns the tuple ``(delta, newexpr)`` where: - ``delta`` is a simple KroneckerDelta expression if one was found, or ``None`` if no simple KroneckerDelta expression was found. - ``newexpr`` is a Mul containing the remaining terms; ``expr`` is returned unchanged if no simple KroneckerDelta expression was found. Examples ======== >>> from sympy import KroneckerDelta >>> from sympy.concrete.delta import _extract_delta >>> from sympy.abc import x, y, i, j, k >>> _extract_delta(4xyKroneckerDelta(i, j), i) (KroneckerDelta(i, j), 4xy) >>> _extract_delta(4xyKroneckerDelta(i, j), k) (None, 4xyKroneckerDelta(i, j)) See Also ======== sympy.functions.special.tensor_functions.KroneckerDelta deltaproduct deltasummation """ if not _has_simple_delta(expr, index): return (None, expr) if isinstance(expr, KroneckerDelta): return (expr, S(1)) if not expr.is_Mul: raise ValueError("Incorrect expr") delta = None terms = [] for arg in expr.args: if delta is None and _is_simple_delta(arg, index): delta = arg else: terms.append(arg) return (delta, expr.func(terms)) @cacheit def _has_simple_delta(expr, index): """ Returns True if ``expr`` is an expression that contains a KroneckerDelta that is simple in the index ``index``, meaning that this KroneckerDelta is nonzero for a single value of the index ``index``. """ if expr.has(KroneckerDelta): if _is_simple_delta(expr, index): return True if expr.is_Add or expr.is_Mul: for arg in expr.args: if _has_simple_delta(arg, index): return True return False @cacheit def _is_simple_delta(delta, index): """ Returns True if ``delta`` is a KroneckerDelta and is nonzero for a single value of the index ``index``. """ if isinstance(delta, KroneckerDelta) and delta.has(index): p = (delta.args[0] - delta.args[1]).as_poly(index) if p: return p.degree() == 1 return False @cacheit def _remove_multiple_delta(expr): """ Evaluate products of KroneckerDelta's. """ from sympy.solvers import solve if expr.is_Add: return expr.func(list(map(_remove_multiple_delta, expr.args))) if not expr.is_Mul: return expr eqs = [] newargs = [] for arg in expr.args: if isinstance(arg, KroneckerDelta): eqs.append(arg.args[0] - arg.args[1]) else: newargs.append(arg) if not eqs: return expr solns = solve(eqs, dict=True) if len(solns) == 0: return S.Zero elif len(solns) == 1: for key in solns[0].keys(): newargs.append(KroneckerDelta(key, solns[0][key])) expr2 = expr.func(newargs) if expr != expr2: return _remove_multiple_delta(expr2) return expr @cacheit def _simplify_delta(expr): """ Rewrite a KroneckerDelta's indices in its simplest form. """ from sympy.solvers import solve if isinstance(expr, KroneckerDelta): try: slns = solve(expr.args[0] - expr.args[1], dict=True) if slns and len(slns) == 1: return Mul([KroneckerDelta((key, value)) for key, value in slns[0].items()]) except NotImplementedError: pass return expr @cacheit def deltaproduct(f, limit): """ Handle products containing a KroneckerDelta. See Also ======== deltasummation sympy.functions.special.tensor_functions.KroneckerDelta sympy.concrete.products.product """ from sympy.concrete.products import product if ((limit[2] - limit[1]) < 0) == True: return S.One if not f.has(KroneckerDelta): return product(f, limit) if f.is_Add: # Identify the term in the Add that has a simple KroneckerDelta delta = None terms = [] for arg in sorted(f.args, key=default_sort_key): if delta is None and _has_simple_delta(arg, limit[0]): delta = arg else: terms.append(arg) newexpr = f.func(terms) k = Dummy("kprime", integer=True) if isinstance(limit[1], int) and isinstance(limit[2], int): result = deltaproduct(newexpr, limit) + sum([ deltaproduct(newexpr, (limit[0], limit[1], ik - 1)) * delta.subs(limit[0], ik) * deltaproduct(newexpr, (limit[0], ik + 1, limit[2])) for ik in range(int(limit[1]), int(limit[2] + 1))] ) else: result = deltaproduct(newexpr, limit) + deltasummation( deltaproduct(newexpr, (limit[0], limit[1], k - 1)) * delta.subs(limit[0], k) * deltaproduct(newexpr, (limit[0], k + 1, limit[2])), (k, limit[1], limit[2]), no_piecewise=_has_simple_delta(newexpr, limit[0]) ) return _remove_multiple_delta(result) delta, _ = _extract_delta(f, limit[0]) if not delta: g = _expand_delta(f, limit[0]) if f != g: from sympy import factor try: return factor(deltaproduct(g, limit)) except AssertionError: return deltaproduct(g, limit) return product(f, limit) from sympy import Eq c = Eq(limit[2], limit[1] - 1) return _remove_multiple_delta(f.subs(limit[0], limit[1])KroneckerDelta(limit[2], limit[1])) + \ S.One_simplify_delta(KroneckerDelta(limit[2], limit[1] - 1)) @cacheit def deltasummation(f, limit, no_piecewise=False): """ Handle summations containing a KroneckerDelta. The idea for summation is the following: - If we are dealing with a KroneckerDelta expression, i.e. KroneckerDelta(g(x), j), we try to simplify it. If we could simplify it, then we sum the resulting expression. We already know we can sum a simplified expression, because only simple KroneckerDelta expressions are involved. If we couldn't simplify it, there are two cases: 1) The expression is a simple expression: we return the summation, taking care if we are dealing with a Derivative or with a proper KroneckerDelta. 2) The expression is not simple (i.e. KroneckerDelta(cos(x))): we can do nothing at all. - If the expr is a multiplication expr having a KroneckerDelta term: First we expand it. If the expansion did work, then we try to sum the expansion. If not, we try to extract a simple KroneckerDelta term, then we have two cases: 1) We have a simple KroneckerDelta term, so we return the summation. 2) We didn't have a simple term, but we do have an expression with simplified KroneckerDelta terms, so we sum this expression. Examples ======== >>> from sympy import oo, symbols >>> from sympy.abc import k >>> i, j = symbols('i, j', integer=True, finite=True) >>> from sympy.concrete.delta import deltasummation >>> from sympy import KroneckerDelta, Piecewise >>> deltasummation(KroneckerDelta(i, k), (k, -oo, oo)) 1 >>> deltasummation(KroneckerDelta(i, k), (k, 0, oo)) Piecewise((1, i >= 0), (0, True)) >>> deltasummation(KroneckerDelta(i, k), (k, 1, 3)) Piecewise((1, (i >= 1) & (i <= 3)), (0, True)) >>> deltasummation(kKroneckerDelta(i, j)KroneckerDelta(j, k), (k, -oo, oo)) jKroneckerDelta(i, j) >>> deltasummation(jKroneckerDelta(i, j), (j, -oo, oo)) i >>> deltasummation(iKroneckerDelta(i, j), (i, -oo, oo)) j See Also ======== deltaproduct sympy.functions.special.tensor_functions.KroneckerDelta sympy.concrete.sums.summation """ from sympy.concrete.summations import summation from sympy.solvers import solve if ((limit[2] - limit[1]) < 0) == True: return S.Zero if not f.has(KroneckerDelta): return summation(f, limit) x = limit[0] g = _expand_delta(f, x) if g.is_Add: return piecewise_fold( g.func([deltasummation(h, limit, no_piecewise) for h in g.args])) # try to extract a simple KroneckerDelta term delta, expr = _extract_delta(g, x) if not delta: return summation(f, limit) solns = solve(delta.args[0] - delta.args[1], x) if len(solns) == 0: return S.Zero elif len(solns) != 1: from sympy.concrete.summations import Sum return Sum(f, limit) value = solns[0] if no_piecewise: return expr.subs(x, value) return Piecewise( (expr.subs(x, value), Interval(*limit[1:3]).as_relational(value)), (S.Zero, True) )
a97181c11f4e152b80739f6e343334679daae5fbf56be7f2ea927c6c24feffc0	"""Various algorithms for helping identifying numbers and sequences.""" from __future__ import print_function, division from sympy.utilities import public from sympy.core import Function, Symbol from sympy.core.compatibility import range from sympy.core.numbers import Zero from sympy import (sympify, floor, lcm, denom, Integer, Rational, exp, integrate, symbols, Product, product) from sympy.polys.polyfuncs import rational_interpolate as rinterp @public def find_simple_recurrence_vector(l): """ This function is used internally by other functions from the sympy.concrete.guess module. While most users may want to rather use the function find_simple_recurrence when looking for recurrence relations among rational numbers, the current function may still be useful when some post-processing has to be done. The function returns a vector of length n when a recurrence relation of order n is detected in the sequence of rational numbers v. If the returned vector has a length 1, then the returned value is always the list [0], which means that no relation has been found. While the functions is intended to be used with rational numbers, it should work for other kinds of real numbers except for some cases involving quadratic numbers; for that reason it should be used with some caution when the argument is not a list of rational numbers. Examples ======== >>> from sympy.concrete.guess import find_simple_recurrence_vector >>> from sympy import fibonacci >>> find_simple_recurrence_vector([fibonacci(k) for k in range(12)]) [1, -1, -1] See Also ======== See the function sympy.concrete.guess.find_simple_recurrence which is more user-friendly. """ q1 = [0] q2 = [Integer(1)] b, z = 0, len(l) >> 1 while len(q2) <= z: while l[b]==0: b += 1 if b == len(l): c = 1 for x in q2: c = lcm(c, denom(x)) if q2[0]c < 0: c = -c for k in range(len(q2)): q2[k] = int(q2[k]c) return q2 a = Integer(1)/l[b] m = [a] for k in range(b+1, len(l)): m.append(-sum(l[j+1]m[b-j-1] for j in range(b, k))a) l, m = m, [0] * max(len(q2), b+len(q1)) for k in range(len(q2)): m[k] = aq2[k] for k in range(b, b+len(q1)): m[k] += q1[k-b] while m[-1]==0: m.pop() # because trailing zeros can occur q1, q2, b = q2, m, 1 return [0] @public def find_simple_recurrence(v, A=Function('a'), N=Symbol('n')): """ Detects and returns a recurrence relation from a sequence of several integer (or rational) terms. The name of the function in the returned expression is 'a' by default; the main variable is 'n' by default. The smallest index in the returned expression is always n (and never n-1, n-2, etc.). Examples ======== >>> from sympy.concrete.guess import find_simple_recurrence >>> from sympy import fibonacci >>> find_simple_recurrence([fibonacci(k) for k in range(12)]) -a(n) - a(n + 1) + a(n + 2) >>> from sympy import Function, Symbol >>> a = [1, 1, 1] >>> for k in range(15): a.append(5a[-1]-3a[-2]+8a[-3]) >>> find_simple_recurrence(a, A=Function('f'), N=Symbol('i')) -8f(i) + 3f(i + 1) - 5f(i + 2) + f(i + 3) """ p = find_simple_recurrence_vector(v) n = len(p) if n <= 1: return Zero() rel = Zero() for k in range(n): rel += A(N+n-1-k)p[k] return rel @public def rationalize(x, maxcoeff=10000): """ Helps identifying a rational number from a float (or mpmath.mpf) value by using a continued fraction. The algorithm stops as soon as a large partial quotient is detected (greater than 10000 by default). Examples ======== >>> from sympy.concrete.guess import rationalize >>> from mpmath import cos, pi >>> rationalize(cos(pi/3)) 1/2 >>> from mpmath import mpf >>> rationalize(mpf("0.333333333333333")) 1/3 While the function is rather intended to help 'identifying' rational values, it may be used in some cases for approximating real numbers. (Though other functions may be more relevant in that case.) >>> rationalize(pi, maxcoeff = 250) 355/113 See Also ======== Several other methods can approximate a real number as a rational, like: * fractions.Fraction.from_decimal * fractions.Fraction.from_float * mpmath.identify * mpmath.pslq by using the following syntax: mpmath.pslq([x, 1]) * mpmath.findpoly by using the following syntax: mpmath.findpoly(x, 1) * sympy.simplify.nsimplify (which is a more general function) The main difference between the current function and all these variants is that control focuses on magnitude of partial quotients here rather than on global precision of the approximation. If the real is "known to be" a rational number, the current function should be able to detect it correctly with the default settings even when denominator is great (unless its expansion contains unusually big partial quotients) which may occur when studying sequences of increasing numbers. If the user cares more on getting simple fractions, other methods may be more convenient. """ p0, p1 = 0, 1 q0, q1 = 1, 0 a = floor(x) while a < maxcoeff or q1==0: p = ap1 + p0 q = aq1 + q0 p0, p1 = p1, p q0, q1 = q1, q if x==a: break x = 1/(x-a) a = floor(x) return sympify(p) / q @public def guess_generating_function_rational(v, X=Symbol('x')): """ Tries to "guess" a rational generating function for a sequence of rational numbers v. Examples ======== >>> from sympy.concrete.guess import guess_generating_function_rational >>> from sympy import fibonacci >>> l = [fibonacci(k) for k in range(5,15)] >>> guess_generating_function_rational(l) (3x + 5)/(-x2 - x + 1) See Also ======== sympy.series.approximants mpmath.pade """ # a) compute the denominator as q q = find_simple_recurrence_vector(v) n = len(q) if n <= 1: return None # b) compute the numerator as p p = [sum(v[i-k]q[k] for k in range(min(i+1, n))) for i in range(len(v)>>1)] return (sum(p[k]Xk for k in range(len(p))) / sum(q[k]X*k for k in range(n))) @public def guess_generating_function(v, X=Symbol('x'), types=['all'], maxsqrtn=2): """ Tries to "guess" a generating function for a sequence of rational numbers v. Only a few patterns are implemented yet. The function returns a dictionary where keys are the name of a given type of generating function. Six types are currently implemented: type \| formal definition -------+---------------------------------------------------------------- ogf \| f(x) = Sum( a_k x^k , k: 0..infinity ) egf \| f(x) = Sum( a_k * x^k / k! , k: 0..infinity ) lgf \| f(x) = Sum( (-1)^(k+1) a_k * x^k / k , k: 1..infinity ) \| (with initial index being hold as 1 rather than 0) hlgf \| f(x) = Sum( a_k * x^k / k , k: 1..infinity ) \| (with initial index being hold as 1 rather than 0) lgdogf \| f(x) = derivate( log(Sum( a_k * x^k, k: 0..infinity )), x) lgdegf \| f(x) = derivate( log(Sum( a_k * x^k / k!, k: 0..infinity )), x) In order to spare time, the user can select only some types of generating functions (default being ['all']). While forgetting to use a list in the case of a single type may seem to work most of the time as in: types='ogf' this (convenient) syntax may lead to unexpected extra results in some cases. Discarding a type when calling the function does not mean that the type will not be present in the returned dictionary; it only means that no extra computation will be performed for that type, but the function may still add it in the result when it can be easily converted from another type. Two generating functions (lgdogf and lgdegf) are not even computed if the initial term of the sequence is 0; it may be useful in that case to try again after having removed the leading zeros. Examples ======== >>> from sympy.concrete.guess import guess_generating_function as ggf >>> ggf([k+1 for k in range(12)], types=['ogf', 'lgf', 'hlgf']) {'hlgf': 1/(-x + 1), 'lgf': 1/(x + 1), 'ogf': 1/(x*2 - 2x + 1)} >>> from sympy import sympify >>> l = sympify("[3/2, 11/2, 0, -121/2, -363/2, 121]") >>> ggf(l) {'ogf': (x + 3/2)/(11x2 - 3x + 1)} >>> from sympy import fibonacci >>> ggf([fibonacci(k) for k in range(5, 15)], types=['ogf']) {'ogf': (3x + 5)/(-x2 - x + 1)} >>> from sympy import simplify, factorial >>> ggf([factorial(k) for k in range(12)], types=['ogf', 'egf', 'lgf']) {'egf': 1/(-x + 1)} >>> ggf([k+1 for k in range(12)], types=['egf']) {'egf': (x + 1)exp(x), 'lgdegf': (x + 2)/(x + 1)} N-th root of a rational function can also be detected (below is an example coming from the sequence A108626 from http://oeis.org). The greatest n-th root to be tested is specified as maxsqrtn (default 2). >>> ggf([1, 2, 5, 14, 41, 124, 383, 1200, 3799, 12122, 38919])['ogf'] sqrt(1/(x*4 + 2x*2 - 4x + 1)) References ========== .. [1] "Concrete Mathematics", R.L. Graham, D.E. Knuth, O. Patashnik .. [2] https://oeis.org/wiki/Generating_functions """ # List of all types of all g.f. known by the algorithm if 'all' in types: types = ['ogf', 'egf', 'lgf', 'hlgf', 'lgdogf', 'lgdegf'] result = {} # Ordinary Generating Function (ogf) if 'ogf' in types: # Perform some convolutions of the sequence with itself t = [1 if k==0 else 0 for k in range(len(v))] for d in range(max(1, maxsqrtn)): t = [sum(t[n-i]v[i] for i in range(n+1)) for n in range(len(v))] g = guess_generating_function_rational(t, X=X) if g: result['ogf'] = gRational(1, d+1) break # Exponential Generating Function (egf) if 'egf' in types: # Transform sequence (division by factorial) w, f = [], Integer(1) for i, k in enumerate(v): f = i if i else 1 w.append(k/f) # Perform some convolutions of the sequence with itself t = [1 if k==0 else 0 for k in range(len(w))] for d in range(max(1, maxsqrtn)): t = [sum(t[n-i]w[i] for i in range(n+1)) for n in range(len(w))] g = guess_generating_function_rational(t, X=X) if g: result['egf'] = gRational(1, d+1) break # Logarithmic Generating Function (lgf) if 'lgf' in types: # Transform sequence (multiplication by (-1)^(n+1) / n) w, f = [], Integer(-1) for i, k in enumerate(v): f = -f w.append(fk/Integer(i+1)) # Perform some convolutions of the sequence with itself t = [1 if k==0 else 0 for k in range(len(w))] for d in range(max(1, maxsqrtn)): t = [sum(t[n-i]w[i] for i in range(n+1)) for n in range(len(w))] g = guess_generating_function_rational(t, X=X) if g: result['lgf'] = gRational(1, d+1) break # Hyperbolic logarithmic Generating Function (hlgf) if 'hlgf' in types: # Transform sequence (division by n+1) w = [] for i, k in enumerate(v): w.append(k/Integer(i+1)) # Perform some convolutions of the sequence with itself t = [1 if k==0 else 0 for k in range(len(w))] for d in range(max(1, maxsqrtn)): t = [sum(t[n-i]w[i] for i in range(n+1)) for n in range(len(w))] g = guess_generating_function_rational(t, X=X) if g: result['hlgf'] = g*Rational(1, d+1) break # Logarithmic derivative of ordinary generating Function (lgdogf) if v[0] != 0 and ('lgdogf' in types or ('ogf' in types and 'ogf' not in result)): # Transform sequence by computing f'(x)/f(x) # because log(f(x)) = integrate( f'(x)/f(x) ) a, w = sympify(v[0]), [] for n in range(len(v)-1): w.append( (v[n+1](n+1) - sum(w[-i-1]v[i+1] for i in range(n)))/a) # Perform some convolutions of the sequence with itself t = [1 if k==0 else 0 for k in range(len(w))] for d in range(max(1, maxsqrtn)): t = [sum(t[n-i]w[i] for i in range(n+1)) for n in range(len(w))] g = guess_generating_function_rational(t, X=X) if g: result['lgdogf'] = g*Rational(1, d+1) if 'ogf' not in result: result['ogf'] = exp(integrate(result['lgdogf'], X)) break # Logarithmic derivative of exponential generating Function (lgdegf) if v[0] != 0 and ('lgdegf' in types or ('egf' in types and 'egf' not in result)): # Transform sequence / step 1 (division by factorial) z, f = [], Integer(1) for i, k in enumerate(v): f = i if i else 1 z.append(k/f) # Transform sequence / step 2 by computing f'(x)/f(x) # because log(f(x)) = integrate( f'(x)/f(x) ) a, w = z[0], [] for n in range(len(z)-1): w.append( (z[n+1](n+1) - sum(w[-i-1]z[i+1] for i in range(n)))/a) # Perform some convolutions of the sequence with itself t = [1 if k==0 else 0 for k in range(len(w))] for d in range(max(1, maxsqrtn)): t = [sum(t[n-i]w[i] for i in range(n+1)) for n in range(len(w))] g = guess_generating_function_rational(t, X=X) if g: result['lgdegf'] = gRational(1, d+1) if 'egf' not in result: result['egf'] = exp(integrate(result['lgdegf'], X)) break return result @public def guess(l, all=False, evaluate=True, niter=2, variables=None): """ This function is adapted from the Rate.m package for Mathematica written by Christian Krattenthaler. It tries to guess a formula from a given sequence of rational numbers. In order to speed up the process, the 'all' variable is set to False by default, stopping the computation as some results are returned during an iteration; the variable can be set to True if more iterations are needed (other formulas may be found; however they may be equivalent to the first ones). Another option is the 'evaluate' variable (default is True); setting it to False will leave the involved products unevaluated. By default, the number of iterations is set to 2 but a greater value (up to len(l)-1) can be specified with the optional 'niter' variable. More and more convoluted results are found when the order of the iteration gets higher: first iteration returns polynomial or rational functions; * second iteration returns products of rising factorials and their inverses; * third iteration returns products of products of rising factorials and their inverses; * etc. The returned formulas contain symbols i0, i1, i2, ... where the main variables is i0 (and auxiliary variables are i1, i2, ...). A list of other symbols can be provided in the 'variables' option; the length of the least should be the value of 'niter' (more is acceptable but only the first symbols will be used); in this case, the main variable will be the first symbol in the list. Examples ======== >>> from sympy.concrete.guess import guess >>> guess([1,2,6,24,120], evaluate=False) [Product(i1 + 1, (i1, 1, i0 - 1))] >>> from sympy import symbols >>> r = guess([1,2,7,42,429,7436,218348,10850216], niter=4) >>> i0 = symbols("i0") >>> [r[0].subs(i0,n).doit() for n in range(1,10)] [1, 2, 7, 42, 429, 7436, 218348, 10850216, 911835460] """ if any(a==0 for a in l[:-1]): return [] N = len(l) niter = min(N-1, niter) myprod = product if evaluate else Product g = [] res = [] if variables == None: symb = symbols('i:'+str(niter)) else: symb = variables for k, s in enumerate(symb): g.append(l) n, r = len(l), [] for i in range(n-2-1, -1, -1): ri = rinterp(enumerate(g[k][:-1], start=1), i, X=s) if ((denom(ri).subs({s:n}) != 0) and (ri.subs({s:n}) - g[k][-1] == 0) and ri not in r): r.append(ri) if r: for i in range(k-1, -1, -1): r = list(map(lambda v: g[i][0] * myprod(v, (symb[i+1], 1, symb[i]-1)), r)) if not all: return r res += r l = [Rational(l[i+1], l[i]) for i in range(N-k-1)] return res
83c71d1e87e856e517f56085ef62d6ec4bf02db3fc7038f7ec80edef64b8804d	from __future__ import print_function, division from sympy.core.add import Add from sympy.core.compatibility import is_sequence from sympy.core.containers import Tuple from sympy.core.expr import Expr from sympy.core.mul import Mul from sympy.core.relational import Equality, Relational from sympy.core.singleton import S from sympy.core.symbol import Symbol, Dummy from sympy.core.sympify import sympify from sympy.functions.elementary.piecewise import (piecewise_fold, Piecewise) from sympy.logic.boolalg import BooleanFunction from sympy.matrices import Matrix from sympy.tensor.indexed import Idx from sympy.sets.sets import Interval from sympy.utilities import flatten from sympy.utilities.iterables import sift def _common_new(cls, function, symbols, assumptions): """Return either a special return value or the tuple, (function, limits, orientation). This code is common to both ExprWithLimits and AddWithLimits.""" function = sympify(function) if hasattr(function, 'func') and isinstance(function, Equality): lhs = function.lhs rhs = function.rhs return Equality(cls(lhs, symbols, *assumptions), \ cls(rhs, symbols, *assumptions)) if function is S.NaN: return S.NaN if symbols: limits, orientation = _process_limits(symbols) else: # symbol not provided -- we can still try to compute a general form free = function.free_symbols if len(free) != 1: raise ValueError( "specify dummy variables for %s" % function) limits, orientation = [Tuple(s) for s in free], 1 # denest any nested calls while cls == type(function): limits = list(function.limits) + limits function = function.function # Any embedded piecewise functions need to be brought out to the # top level. We only fold Piecewise that contain the integration # variable. reps = {} symbols_of_integration = set([i[0] for i in limits]) for p in function.atoms(Piecewise): if not p.has(symbols_of_integration): reps[p] = Dummy() # mask off those that don't function = function.xreplace(reps) # do the fold function = piecewise_fold(function) # remove the masking function = function.xreplace({v: k for k, v in reps.items()}) return function, limits, orientation def _process_limits(symbols): """Process the list of symbols and convert them to canonical limits, storing them as Tuple(symbol, lower, upper). The orientation of the function is also returned when the upper limit is missing so (x, 1, None) becomes (x, None, 1) and the orientation is changed. """ limits = [] orientation = 1 for V in symbols: if isinstance(V, (Relational, BooleanFunction)): variable = V.atoms(Symbol).pop() V = (variable, V.as_set()) if isinstance(V, Symbol) or getattr(V, '_diff_wrt', False): if isinstance(V, Idx): if V.lower is None or V.upper is None: limits.append(Tuple(V)) else: limits.append(Tuple(V, V.lower, V.upper)) else: limits.append(Tuple(V)) continue elif is_sequence(V, Tuple): V = sympify(flatten(V)) if isinstance(V[0], (Symbol, Idx)) or getattr(V[0], '_diff_wrt', False): newsymbol = V[0] if len(V) == 2 and isinstance(V[1], Interval): V[1:] = [V[1].start, V[1].end] if len(V) == 3: if V[1] is None and V[2] is not None: nlim = [V[2]] elif V[1] is not None and V[2] is None: orientation = -1 nlim = [V[1]] elif V[1] is None and V[2] is None: nlim = [] else: nlim = V[1:] limits.append(Tuple(newsymbol, nlim)) if isinstance(V[0], Idx): if V[0].lower is not None and not bool(nlim[0] >= V[0].lower): raise ValueError("Summation exceeds Idx lower range.") if V[0].upper is not None and not bool(nlim[1] <= V[0].upper): raise ValueError("Summation exceeds Idx upper range.") continue elif len(V) == 1 or (len(V) == 2 and V[1] is None): limits.append(Tuple(newsymbol)) continue elif len(V) == 2: limits.append(Tuple(newsymbol, V[1])) continue raise ValueError('Invalid limits given: %s' % str(symbols)) return limits, orientation class ExprWithLimits(Expr): __slots__ = ['is_commutative'] def __new__(cls, function, symbols, assumptions): pre = _common_new(cls, function, symbols, assumptions) if type(pre) is tuple: function, limits, _ = pre else: return pre # limits must have upper and lower bounds; the indefinite form # is not supported. This restriction does not apply to AddWithLimits if any(len(l) != 3 or None in l for l in limits): raise ValueError('ExprWithLimits requires values for lower and upper bounds.') obj = Expr.__new__(cls, assumptions) arglist = [function] arglist.extend(limits) obj._args = tuple(arglist) obj.is_commutative = function.is_commutative # limits already checked return obj @property def function(self): """Return the function applied across limits. Examples ======== >>> from sympy import Integral >>> from sympy.abc import x >>> Integral(x2, (x,)).function x2 See Also ======== limits, variables, free_symbols """ return self._args[0] @property def limits(self): """Return the limits of expression. Examples ======== >>> from sympy import Integral >>> from sympy.abc import x, i >>> Integral(xi, (i, 1, 3)).limits ((i, 1, 3),) See Also ======== function, variables, free_symbols """ return self._args[1:] @property def variables(self): """Return a list of the limit variables. >>> from sympy import Sum >>> from sympy.abc import x, i >>> Sum(xi, (i, 1, 3)).variables [i] See Also ======== function, limits, free_symbols as_dummy : Rename dummy variables transform : Perform mapping on the dummy variable """ return [l[0] for l in self.limits] @property def bound_symbols(self): """Return only variables that are dummy variables. Examples ======== >>> from sympy import Integral >>> from sympy.abc import x, i, j, k >>> Integral(x*i, (i, 1, 3), (j, 2), k).bound_symbols [i, j] See Also ======== function, limits, free_symbols as_dummy : Rename dummy variables transform : Perform mapping on the dummy variable """ return [l[0] for l in self.limits if len(l) != 1] @property def free_symbols(self): """ This method returns the symbols in the object, excluding those that take on a specific value (i.e. the dummy symbols). Examples ======== >>> from sympy import Sum >>> from sympy.abc import x, y >>> Sum(x, (x, y, 1)).free_symbols {y} """ # don't test for any special values -- nominal free symbols # should be returned, e.g. don't return set() if the # function is zero -- treat it like an unevaluated expression. function, limits = self.function, self.limits isyms = function.free_symbols for xab in limits: if len(xab) == 1: isyms.add(xab[0]) continue # take out the target symbol if xab[0] in isyms: isyms.remove(xab[0]) # add in the new symbols for i in xab[1:]: isyms.update(i.free_symbols) return isyms @property def is_number(self): """Return True if the Sum has no free symbols, else False.""" return not self.free_symbols def _eval_interval(self, x, a, b): limits = [(i if i[0] != x else (x, a, b)) for i in self.limits] integrand = self.function return self.func(integrand, limits) def _eval_subs(self, old, new): """ Perform substitutions over non-dummy variables of an expression with limits. Also, can be used to specify point-evaluation of an abstract antiderivative. Examples ======== >>> from sympy import Sum, oo >>> from sympy.abc import s, n >>> Sum(1/ns, (n, 1, oo)).subs(s, 2) Sum(n(-2), (n, 1, oo)) >>> from sympy import Integral >>> from sympy.abc import x, a >>> Integral(ax2, x).subs(x, 4) Integral(ax*2, (x, 4)) See Also ======== variables : Lists the integration variables transform : Perform mapping on the dummy variable for integrals change_index : Perform mapping on the sum and product dummy variables """ from sympy.core.function import AppliedUndef, UndefinedFunction func, limits = self.function, list(self.limits) # If one of the expressions we are replacing is used as a func index # one of two things happens. # - the old variable first appears as a free variable # so we perform all free substitutions before it becomes # a func index. # - the old variable first appears as a func index, in # which case we ignore. See change_index. # Reorder limits to match standard mathematical practice for scoping limits.reverse() if not isinstance(old, Symbol) or \ old.free_symbols.intersection(self.free_symbols): sub_into_func = True for i, xab in enumerate(limits): if 1 == len(xab) and old == xab[0]: if new._diff_wrt: xab = (new,) else: xab = (old, old) limits[i] = Tuple(xab[0], [l._subs(old, new) for l in xab[1:]]) if len(xab[0].free_symbols.intersection(old.free_symbols)) != 0: sub_into_func = False break if isinstance(old, AppliedUndef) or isinstance(old, UndefinedFunction): sy2 = set(self.variables).intersection(set(new.atoms(Symbol))) sy1 = set(self.variables).intersection(set(old.args)) if not sy2.issubset(sy1): raise ValueError( "substitution can not create dummy dependencies") sub_into_func = True if sub_into_func: func = func.subs(old, new) else: # old is a Symbol and a dummy variable of some limit for i, xab in enumerate(limits): if len(xab) == 3: limits[i] = Tuple(xab[0], [l._subs(old, new) for l in xab[1:]]) if old == xab[0]: break # simplify redundant limits (x, x) to (x, ) for i, xab in enumerate(limits): if len(xab) == 2 and (xab[0] - xab[1]).is_zero: limits[i] = Tuple(xab[0], ) # Reorder limits back to representation-form limits.reverse() return self.func(func, limits) class AddWithLimits(ExprWithLimits): r"""Represents unevaluated oriented additions. Parent class for Integral and Sum. """ def __new__(cls, function, symbols, assumptions): pre = _common_new(cls, function, symbols, assumptions) if type(pre) is tuple: function, limits, orientation = pre else: return pre obj = Expr.__new__(cls, assumptions) arglist = [orientationfunction] # orientation not used in ExprWithLimits arglist.extend(limits) obj._args = tuple(arglist) obj.is_commutative = function.is_commutative # limits already checked return obj def _eval_adjoint(self): if all([x.is_real for x in flatten(self.limits)]): return self.func(self.function.adjoint(), self.limits) return None def _eval_conjugate(self): if all([x.is_real for x in flatten(self.limits)]): return self.func(self.function.conjugate(), self.limits) return None def _eval_transpose(self): if all([x.is_real for x in flatten(self.limits)]): return self.func(self.function.transpose(), self.limits) return None def _eval_factor(self, hints): if 1 == len(self.limits): summand = self.function.factor(hints) if summand.is_Mul: out = sift(summand.args, lambda w: w.is_commutative \ and not set(self.variables) & w.free_symbols) return Mul(out[True])self.func(Mul(out[False]), \ self.limits) else: summand = self.func(self.function, self.limits[0:-1]).factor() if not summand.has(self.variables[-1]): return self.func(1, [self.limits[-1]]).doit()summand elif isinstance(summand, Mul): return self.func(summand, self.limits[-1]).factor() return self def _eval_expand_basic(self, hints): summand = self.function.expand(hints) if summand.is_Add and summand.is_commutative: return Add([self.func(i, self.limits) for i in summand.args]) elif summand.is_Matrix: return Matrix._new(summand.rows, summand.cols, [self.func(i, self.limits) for i in summand._mat]) elif summand != self.function: return self.func(summand, self.limits) return self
d774bc1c3217a0df1f74a685ed8b01acc82e1fa3ee117f3cec35c5a2be21319b	from __future__ import print_function, division from sympy.calculus.singularities import is_decreasing from sympy.calculus.util import AccumulationBounds from sympy.concrete.expr_with_limits import AddWithLimits from sympy.concrete.expr_with_intlimits import ExprWithIntLimits from sympy.concrete.gosper import gosper_sum from sympy.core.add import Add from sympy.core.compatibility import range from sympy.core.function import Derivative from sympy.core.mul import Mul from sympy.core.relational import Eq from sympy.core.singleton import S from sympy.core.symbol import Dummy, Wild, Symbol from sympy.functions.special.zeta_functions import zeta from sympy.functions.elementary.piecewise import Piecewise from sympy.logic.boolalg import And from sympy.polys import apart, PolynomialError, together from sympy.series.limitseq import limit_seq from sympy.series.order import O from sympy.sets.sets import FiniteSet from sympy.simplify import denom from sympy.simplify.combsimp import combsimp from sympy.simplify.powsimp import powsimp from sympy.solvers import solve from sympy.solvers.solveset import solveset import itertools class Sum(AddWithLimits, ExprWithIntLimits): r"""Represents unevaluated summation. ``Sum`` represents a finite or infinite series, with the first argument being the general form of terms in the series, and the second argument being ``(dummy_variable, start, end)``, with ``dummy_variable`` taking all integer values from ``start`` through ``end``. In accordance with long-standing mathematical convention, the end term is included in the summation. Finite sums =========== For finite sums (and sums with symbolic limits assumed to be finite) we follow the summation convention described by Karr [1], especially definition 3 of section 1.4. The sum: .. math:: \sum_{m \leq i < n} f(i) has the obvious meaning for `m < n`, namely: .. math:: \sum_{m \leq i < n} f(i) = f(m) + f(m+1) + \ldots + f(n-2) + f(n-1) with the upper limit value `f(n)` excluded. The sum over an empty set is zero if and only if `m = n`: .. math:: \sum_{m \leq i < n} f(i) = 0 \quad \mathrm{for} \quad m = n Finally, for all other sums over empty sets we assume the following definition: .. math:: \sum_{m \leq i < n} f(i) = - \sum_{n \leq i < m} f(i) \quad \mathrm{for} \quad m > n It is important to note that Karr defines all sums with the upper limit being exclusive. This is in contrast to the usual mathematical notation, but does not affect the summation convention. Indeed we have: .. math:: \sum_{m \leq i < n} f(i) = \sum_{i = m}^{n - 1} f(i) where the difference in notation is intentional to emphasize the meaning, with limits typeset on the top being inclusive. Examples ======== >>> from sympy.abc import i, k, m, n, x >>> from sympy import Sum, factorial, oo, IndexedBase, Function >>> Sum(k, (k, 1, m)) Sum(k, (k, 1, m)) >>> Sum(k, (k, 1, m)).doit() m2/2 + m/2 >>> Sum(k2, (k, 1, m)) Sum(k2, (k, 1, m)) >>> Sum(k2, (k, 1, m)).doit() m3/3 + m2/2 + m/6 >>> Sum(xk, (k, 0, oo)) Sum(xk, (k, 0, oo)) >>> Sum(xk, (k, 0, oo)).doit() Piecewise((1/(-x + 1), Abs(x) < 1), (Sum(xk, (k, 0, oo)), True)) >>> Sum(xk/factorial(k), (k, 0, oo)).doit() exp(x) Here are examples to do summation with symbolic indices. You can use either Function of IndexedBase classes: >>> f = Function('f') >>> Sum(f(n), (n, 0, 3)).doit() f(0) + f(1) + f(2) + f(3) >>> Sum(f(n), (n, 0, oo)).doit() Sum(f(n), (n, 0, oo)) >>> f = IndexedBase('f') >>> Sum(f[n]2, (n, 0, 3)).doit() f[0]2 + f[1]2 + f[2]2 + f[3]2 An example showing that the symbolic result of a summation is still valid for seemingly nonsensical values of the limits. Then the Karr convention allows us to give a perfectly valid interpretation to those sums by interchanging the limits according to the above rules: >>> S = Sum(i, (i, 1, n)).doit() >>> S n2/2 + n/2 >>> S.subs(n, -4) 6 >>> Sum(i, (i, 1, -4)).doit() 6 >>> Sum(-i, (i, -3, 0)).doit() 6 An explicit example of the Karr summation convention: >>> S1 = Sum(i2, (i, m, m+n-1)).doit() >>> S1 m*2n + mn2 - mn + n3/3 - n2/2 + n/6 >>> S2 = Sum(i2, (i, m+n, m-1)).doit() >>> S2 -m2n - mn*2 + mn - n3/3 + n2/2 - n/6 >>> S1 + S2 0 >>> S3 = Sum(i, (i, m, m-1)).doit() >>> S3 0 See Also ======== summation Product, product References ========== .. [1] Michael Karr, "Summation in Finite Terms", Journal of the ACM, Volume 28 Issue 2, April 1981, Pages 305-350 http://dl.acm.org/citation.cfm?doid=322248.322255 .. [2] https://en.wikipedia.org/wiki/Summation#Capital-sigma_notation .. [3] https://en.wikipedia.org/wiki/Empty_sum """ __slots__ = ['is_commutative'] def __new__(cls, function, symbols, assumptions): obj = AddWithLimits.__new__(cls, function, symbols, assumptions) if not hasattr(obj, 'limits'): return obj if any(len(l) != 3 or None in l for l in obj.limits): raise ValueError('Sum requires values for lower and upper bounds.') return obj def _eval_is_zero(self): # a Sum is only zero if its function is zero or if all terms # cancel out. This only answers whether the summand is zero; if # not then None is returned since we don't analyze whether all # terms cancel out. if self.function.is_zero: return True def doit(self, hints): if hints.get('deep', True): f = self.function.doit(*hints) else: f = self.function if self.function.is_Matrix: return self.expand().doit() for n, limit in enumerate(self.limits): i, a, b = limit dif = b - a if dif.is_integer and (dif < 0) == True: a, b = b + 1, a - 1 f = -f newf = eval_sum(f, (i, a, b)) if newf is None: if f == self.function: zeta_function = self.eval_zeta_function(f, (i, a, b)) if zeta_function is not None: return zeta_function return self else: return self.func(f, self.limits[n:]) f = newf if hints.get('deep', True): # eval_sum could return partially unevaluated # result with Piecewise. In this case we won't # doit() recursively. if not isinstance(f, Piecewise): return f.doit(*hints) return f def eval_zeta_function(self, f, limits): """ Check whether the function matches with the zeta function. If it matches, then return a `Piecewise` expression because zeta function does not converge unless `s > 1` and `q > 0` """ i, a, b = limits w, y, z = Wild('w', exclude=[i]), Wild('y', exclude=[i]), Wild('z', exclude=[i]) result = f.match((w i + y) (-z)) if result is not None and b == S.Infinity: coeff = 1 / result[w] result[z] s = result[z] q = result[y] / result[w] + a return Piecewise((coeff * zeta(s, q), And(q > 0, s > 1)), (self, True)) def _eval_derivative(self, x): """ Differentiate wrt x as long as x is not in the free symbols of any of the upper or lower limits. Sum(abx, (x, 1, a)) can be differentiated wrt x or b but not `a` since the value of the sum is discontinuous in `a`. In a case involving a limit variable, the unevaluated derivative is returned. """ # diff already confirmed that x is in the free symbols of self, but we # don't want to differentiate wrt any free symbol in the upper or lower # limits # XXX remove this test for free_symbols when the default _eval_derivative is in if isinstance(x, Symbol) and x not in self.free_symbols: return S.Zero # get limits and the function f, limits = self.function, list(self.limits) limit = limits.pop(-1) if limits: # f is the argument to a Sum f = self.func(f, limits) if len(limit) == 3: _, a, b = limit if x in a.free_symbols or x in b.free_symbols: return None df = Derivative(f, x, evaluate=True) rv = self.func(df, limit) return rv else: return NotImplementedError('Lower and upper bound expected.') def _eval_difference_delta(self, n, step): k, _, upper = self.args[-1] new_upper = upper.subs(n, n + step) if len(self.args) == 2: f = self.args[0] else: f = self.func(self.args[:-1]) return Sum(f, (k, upper + 1, new_upper)).doit() def _eval_simplify(self, ratio=1.7, measure=None, rational=False, inverse=False): from sympy.simplify.simplify import factor_sum, sum_combine from sympy.core.function import expand from sympy.core.mul import Mul # split the function into adds terms = Add.make_args(expand(self.function)) s_t = [] # Sum Terms o_t = [] # Other Terms for term in terms: if term.has(Sum): # if there is an embedded sum here # it is of the form x * (Sum(whatever)) # hence we make a Mul out of it, and simplify all interior sum terms subterms = Mul.make_args(expand(term)) out_terms = [] for subterm in subterms: # go through each term if isinstance(subterm, Sum): # if it's a sum, simplify it out_terms.append(subterm._eval_simplify()) else: # otherwise, add it as is out_terms.append(subterm) # turn it back into a Mul s_t.append(Mul(out_terms)) else: o_t.append(term) # next try to combine any interior sums for further simplification result = Add(sum_combine(s_t), o_t) return factor_sum(result, limits=self.limits) def _eval_summation(self, f, x): return None def is_convergent(self): r"""Checks for the convergence of a Sum. We divide the study of convergence of infinite sums and products in two parts. First Part: One part is the question whether all the terms are well defined, i.e., they are finite in a sum and also non-zero in a product. Zero is the analogy of (minus) infinity in products as :math:`e^{-\infty} = 0`. Second Part: The second part is the question of convergence after infinities, and zeros in products, have been omitted assuming that their number is finite. This means that we only consider the tail of the sum or product, starting from some point after which all terms are well defined. For example, in a sum of the form: .. math:: \sum_{1 \leq i < \infty} \frac{1}{n^2 + an + b} where a and b are numbers. The routine will return true, even if there are infinities in the term sequence (at most two). An analogous product would be: .. math:: \prod_{1 \leq i < \infty} e^{\frac{1}{n^2 + an + b}} This is how convergence is interpreted. It is concerned with what happens at the limit. Finding the bad terms is another independent matter. Note: It is responsibility of user to see that the sum or product is well defined. There are various tests employed to check the convergence like divergence test, root test, integral test, alternating series test, comparison tests, Dirichlet tests. It returns true if Sum is convergent and false if divergent and NotImplementedError if it can not be checked. References ========== .. [1] https://en.wikipedia.org/wiki/Convergence_tests Examples ======== >>> from sympy import factorial, S, Sum, Symbol, oo >>> n = Symbol('n', integer=True) >>> Sum(n/(n - 1), (n, 4, 7)).is_convergent() True >>> Sum(n/(2n + 1), (n, 1, oo)).is_convergent() False >>> Sum(factorial(n)/5n, (n, 1, oo)).is_convergent() False >>> Sum(1/n(S(6)/5), (n, 1, oo)).is_convergent() True See Also ======== Sum.is_absolutely_convergent() Product.is_convergent() """ from sympy import Interval, Integral, log, symbols, simplify p, q, r = symbols('p q r', cls=Wild) sym = self.limits[0][0] lower_limit = self.limits[0][1] upper_limit = self.limits[0][2] sequence_term = self.function if len(sequence_term.free_symbols) > 1: raise NotImplementedError("convergence checking for more than one symbol " "containing series is not handled") if lower_limit.is_finite and upper_limit.is_finite: return S.true # transform sym -> -sym and swap the upper_limit = S.Infinity # and lower_limit = - upper_limit if lower_limit is S.NegativeInfinity: if upper_limit is S.Infinity: return Sum(sequence_term, (sym, 0, S.Infinity)).is_convergent() and \ Sum(sequence_term, (sym, S.NegativeInfinity, 0)).is_convergent() sequence_term = simplify(sequence_term.xreplace({sym: -sym})) lower_limit = -upper_limit upper_limit = S.Infinity sym_ = Dummy(sym.name, integer=True, positive=True) sequence_term = sequence_term.xreplace({sym: sym_}) sym = sym_ interval = Interval(lower_limit, upper_limit) # Piecewise function handle if sequence_term.is_Piecewise: for func, cond in sequence_term.args: # see if it represents something going to oo if cond == True or cond.as_set().sup is S.Infinity: s = Sum(func, (sym, lower_limit, upper_limit)) return s.is_convergent() return S.true ### -------- Divergence test ----------- ### try: lim_val = limit_seq(sequence_term, sym) if lim_val is not None and lim_val.is_zero is False: return S.false except NotImplementedError: pass try: lim_val_abs = limit_seq(abs(sequence_term), sym) if lim_val_abs is not None and lim_val_abs.is_zero is False: return S.false except NotImplementedError: pass order = O(sequence_term, (sym, S.Infinity)) ### --------- p-series test (1/np) ---------- ### p1_series_test = order.expr.match(symp) if p1_series_test is not None: if p1_series_test[p] < -1: return S.true if p1_series_test[p] >= -1: return S.false p2_series_test = order.expr.match((1/sym)p) if p2_series_test is not None: if p2_series_test[p] > 1: return S.true if p2_series_test[p] <= 1: return S.false ### ------------- comparison test ------------- ### # 1/(nplog(n)*qlog(log(n))r) comparison n_log_test = order.expr.match(1/(symplog(sym)qlog(log(sym))*r)) if n_log_test is not None: if (n_log_test[p] > 1 or (n_log_test[p] == 1 and n_log_test[q] > 1) or (n_log_test[p] == n_log_test[q] == 1 and n_log_test[r] > 1)): return S.true return S.false ### ------------- Limit comparison test -----------### # (1/n) comparison try: lim_comp = limit_seq(symsequence_term, sym) if lim_comp is not None and lim_comp.is_number and lim_comp > 0: return S.false except NotImplementedError: pass ### ----------- ratio test ---------------- ### next_sequence_term = sequence_term.xreplace({sym: sym + 1}) ratio = combsimp(powsimp(next_sequence_term/sequence_term)) try: lim_ratio = limit_seq(ratio, sym) if lim_ratio is not None and lim_ratio.is_number: if abs(lim_ratio) > 1: return S.false if abs(lim_ratio) < 1: return S.true except NotImplementedError: pass ### ----------- root test ---------------- ### # lim = Limit(abs(sequence_term)(1/sym), sym, S.Infinity) try: lim_evaluated = limit_seq(abs(sequence_term)(1/sym), sym) if lim_evaluated is not None and lim_evaluated.is_number: if lim_evaluated < 1: return S.true if lim_evaluated > 1: return S.false except NotImplementedError: pass ### ------------- alternating series test ----------- ### dict_val = sequence_term.match((-1)*(sym + p)q) if not dict_val[p].has(sym) and is_decreasing(dict_val[q], interval): return S.true ### ------------- integral test -------------- ### check_interval = None maxima = solveset(sequence_term.diff(sym), sym, interval) if not maxima: check_interval = interval elif isinstance(maxima, FiniteSet) and maxima.sup.is_number: check_interval = Interval(maxima.sup, interval.sup) if (check_interval is not None and (is_decreasing(sequence_term, check_interval) or is_decreasing(-sequence_term, check_interval))): integral_val = Integral( sequence_term, (sym, lower_limit, upper_limit)) try: integral_val_evaluated = integral_val.doit() if integral_val_evaluated.is_number: return S(integral_val_evaluated.is_finite) except NotImplementedError: pass ### ----- Dirichlet and bounded times convergent tests ----- ### # TODO # # Dirichlet_test # https://en.wikipedia.org/wiki/Dirichlet%27s_test # # Bounded times convergent test # It is based on comparison theorems for series. # In particular, if the general term of a series can # be written as a product of two terms a_n and b_n # and if a_n is bounded and if Sum(b_n) is absolutely # convergent, then the original series Sum(a_n * b_n) # is absolutely convergent and so convergent. # # The following code can grows like 2*n where n is the # number of args in order.expr # Possibly combined with the potentially slow checks # inside the loop, could make this test extremely slow # for larger summation expressions. if order.expr.is_Mul: args = order.expr.args argset = set(args) ### -------------- Dirichlet tests -------------- ### m = Dummy('m', integer=True) def _dirichlet_test(g_n): try: ing_val = limit_seq(Sum(g_n, (sym, interval.inf, m)).doit(), m) if ing_val is not None and ing_val.is_finite: return S.true except NotImplementedError: pass ### -------- bounded times convergent test ---------### def _bounded_convergent_test(g1_n, g2_n): try: lim_val = limit_seq(g1_n, sym) if lim_val is not None and (lim_val.is_finite or ( isinstance(lim_val, AccumulationBounds) and (lim_val.max - lim_val.min).is_finite)): if Sum(g2_n, (sym, lower_limit, upper_limit)).is_absolutely_convergent(): return S.true except NotImplementedError: pass for n in range(1, len(argset)): for a_tuple in itertools.combinations(args, n): b_set = argset - set(a_tuple) a_n = Mul(a_tuple) b_n = Mul(b_set) if is_decreasing(a_n, interval): dirich = _dirichlet_test(b_n) if dirich is not None: return dirich bc_test = _bounded_convergent_test(a_n, b_n) if bc_test is not None: return bc_test _sym = self.limits[0][0] sequence_term = sequence_term.xreplace({sym: _sym}) raise NotImplementedError("The algorithm to find the Sum convergence of %s " "is not yet implemented" % (sequence_term)) def is_absolutely_convergent(self): """ Checks for the absolute convergence of an infinite series. Same as checking convergence of absolute value of sequence_term of an infinite series. References ========== .. [1] https://en.wikipedia.org/wiki/Absolute_convergence Examples ======== >>> from sympy import Sum, Symbol, sin, oo >>> n = Symbol('n', integer=True) >>> Sum((-1)n, (n, 1, oo)).is_absolutely_convergent() False >>> Sum((-1)n/n2, (n, 1, oo)).is_absolutely_convergent() True See Also ======== Sum.is_convergent() """ return Sum(abs(self.function), self.limits).is_convergent() def euler_maclaurin(self, m=0, n=0, eps=0, eval_integral=True): """ Return an Euler-Maclaurin approximation of self, where m is the number of leading terms to sum directly and n is the number of terms in the tail. With m = n = 0, this is simply the corresponding integral plus a first-order endpoint correction. Returns (s, e) where s is the Euler-Maclaurin approximation and e is the estimated error (taken to be the magnitude of the first omitted term in the tail): >>> from sympy.abc import k, a, b >>> from sympy import Sum >>> Sum(1/k, (k, 2, 5)).doit().evalf() 1.28333333333333 >>> s, e = Sum(1/k, (k, 2, 5)).euler_maclaurin() >>> s -log(2) + 7/20 + log(5) >>> from sympy import sstr >>> print(sstr((s.evalf(), e.evalf()), full_prec=True)) (1.26629073187415, 0.0175000000000000) The endpoints may be symbolic: >>> s, e = Sum(1/k, (k, a, b)).euler_maclaurin() >>> s -log(a) + log(b) + 1/(2b) + 1/(2a) >>> e Abs(1/(12b*2) - 1/(12a2)) If the function is a polynomial of degree at most 2n+1, the Euler-Maclaurin formula becomes exact (and e = 0 is returned): >>> Sum(k, (k, 2, b)).euler_maclaurin() (b2/2 + b/2 - 1, 0) >>> Sum(k, (k, 2, b)).doit() b*2/2 + b/2 - 1 With a nonzero eps specified, the summation is ended as soon as the remainder term is less than the epsilon. """ from sympy.functions import bernoulli, factorial from sympy.integrals import Integral m = int(m) n = int(n) f = self.function if len(self.limits) != 1: raise ValueError("More than 1 limit") i, a, b = self.limits[0] if (a > b) == True: if a - b == 1: return S.Zero, S.Zero a, b = b + 1, a - 1 f = -f s = S.Zero if m: if b.is_Integer and a.is_Integer: m = min(m, b - a + 1) if not eps or f.is_polynomial(i): for k in range(m): s += f.subs(i, a + k) else: term = f.subs(i, a) if term: test = abs(term.evalf(3)) < eps if test == True: return s, abs(term) elif not (test == False): # a symbolic Relational class, can't go further return term, S.Zero s += term for k in range(1, m): term = f.subs(i, a + k) if abs(term.evalf(3)) < eps and term != 0: return s, abs(term) s += term if b - a + 1 == m: return s, S.Zero a += m x = Dummy('x') I = Integral(f.subs(i, x), (x, a, b)) if eval_integral: I = I.doit() s += I def fpoint(expr): if b is S.Infinity: return expr.subs(i, a), 0 return expr.subs(i, a), expr.subs(i, b) fa, fb = fpoint(f) iterm = (fa + fb)/2 g = f.diff(i) for k in range(1, n + 2): ga, gb = fpoint(g) term = bernoulli(2k)/factorial(2k)(gb - ga) if (eps and term and abs(term.evalf(3)) < eps) or (k > n): break s += term g = g.diff(i, 2, simplify=False) return s + iterm, abs(term) def reverse_order(self, indices): """ Reverse the order of a limit in a Sum. Usage ===== ``reverse_order(self, indices)`` reverses some limits in the expression ``self`` which can be either a ``Sum`` or a ``Product``. The selectors in the argument ``indices`` specify some indices whose limits get reversed. These selectors are either variable names or numerical indices counted starting from the inner-most limit tuple. Examples ======== >>> from sympy import Sum >>> from sympy.abc import x, y, a, b, c, d >>> Sum(x, (x, 0, 3)).reverse_order(x) Sum(-x, (x, 4, -1)) >>> Sum(xy, (x, 1, 5), (y, 0, 6)).reverse_order(x, y) Sum(xy, (x, 6, 0), (y, 7, -1)) >>> Sum(x, (x, a, b)).reverse_order(x) Sum(-x, (x, b + 1, a - 1)) >>> Sum(x, (x, a, b)).reverse_order(0) Sum(-x, (x, b + 1, a - 1)) While one should prefer variable names when specifying which limits to reverse, the index counting notation comes in handy in case there are several symbols with the same name. >>> S = Sum(x2, (x, a, b), (x, c, d)) >>> S Sum(x2, (x, a, b), (x, c, d)) >>> S0 = S.reverse_order(0) >>> S0 Sum(-x2, (x, b + 1, a - 1), (x, c, d)) >>> S1 = S0.reverse_order(1) >>> S1 Sum(x2, (x, b + 1, a - 1), (x, d + 1, c - 1)) Of course we can mix both notations: >>> Sum(xy, (x, a, b), (y, 2, 5)).reverse_order(x, 1) Sum(xy, (x, b + 1, a - 1), (y, 6, 1)) >>> Sum(xy, (x, a, b), (y, 2, 5)).reverse_order(y, x) Sum(xy, (x, b + 1, a - 1), (y, 6, 1)) See Also ======== index, reorder_limit, reorder References ========== .. [1] Michael Karr, "Summation in Finite Terms", Journal of the ACM, Volume 28 Issue 2, April 1981, Pages 305-350 http://dl.acm.org/citation.cfm?doid=322248.322255 """ l_indices = list(indices) for i, indx in enumerate(l_indices): if not isinstance(indx, int): l_indices[i] = self.index(indx) e = 1 limits = [] for i, limit in enumerate(self.limits): l = limit if i in l_indices: e = -e l = (limit[0], limit[2] + 1, limit[1] - 1) limits.append(l) return Sum(e * self.function, limits) def summation(f, symbols, *kwargs): r""" Compute the summation of f with respect to symbols. The notation for symbols is similar to the notation used in Integral. summation(f, (i, a, b)) computes the sum of f with respect to i from a to b, i.e., :: b ____ \ ` summation(f, (i, a, b)) = ) f /___, i = a If it cannot compute the sum, it returns an unevaluated Sum object. Repeated sums can be computed by introducing additional symbols tuples:: >>> from sympy import summation, oo, symbols, log >>> i, n, m = symbols('i n m', integer=True) >>> summation(2i - 1, (i, 1, n)) n2 >>> summation(1/2i, (i, 0, oo)) 2 >>> summation(1/log(n)n, (n, 2, oo)) Sum(log(n)(-n), (n, 2, oo)) >>> summation(i, (i, 0, n), (n, 0, m)) m3/6 + m2/2 + m/3 >>> from sympy.abc import x >>> from sympy import factorial >>> summation(x*n/factorial(n), (n, 0, oo)) exp(x) See Also ======== Sum Product, product """ return Sum(f, symbols, *kwargs).doit(deep=False) def telescopic_direct(L, R, n, limits): """Returns the direct summation of the terms of a telescopic sum L is the term with lower index R is the term with higher index n difference between the indexes of L and R For example: >>> from sympy.concrete.summations import telescopic_direct >>> from sympy.abc import k, a, b >>> telescopic_direct(1/k, -1/(k+2), 2, (k, a, b)) -1/(b + 2) - 1/(b + 1) + 1/(a + 1) + 1/a """ (i, a, b) = limits s = 0 for m in range(n): s += L.subs(i, a + m) + R.subs(i, b - m) return s def telescopic(L, R, limits): '''Tries to perform the summation using the telescopic property return None if not possible ''' (i, a, b) = limits if L.is_Add or R.is_Add: return None # We want to solve(L.subs(i, i + m) + R, m) # First we try a simple match since this does things that # solve doesn't do, e.g. solve(f(k+m)-f(k), m) fails k = Wild("k") sol = (-R).match(L.subs(i, i + k)) s = None if sol and k in sol: s = sol[k] if not (s.is_Integer and L.subs(i, i + s) == -R): # sometimes match fail(f(x+2).match(-f(x+k))->{k: -2 - 2x})) s = None # But there are things that match doesn't do that solve # can do, e.g. determine that 1/(x + m) = 1/(1 - x) when m = 1 if s is None: m = Dummy('m') try: sol = solve(L.subs(i, i + m) + R, m) or [] except NotImplementedError: return None sol = [si for si in sol if si.is_Integer and (L.subs(i, i + si) + R).expand().is_zero] if len(sol) != 1: return None s = sol[0] if s < 0: return telescopic_direct(R, L, abs(s), (i, a, b)) elif s > 0: return telescopic_direct(L, R, s, (i, a, b)) def eval_sum(f, limits): from sympy.concrete.delta import deltasummation, _has_simple_delta from sympy.functions import KroneckerDelta (i, a, b) = limits if f is S.Zero: return S.Zero if i not in f.free_symbols: return f(b - a + 1) if a == b: return f.subs(i, a) if isinstance(f, Piecewise): if not any(i in arg.args[1].free_symbols for arg in f.args): # Piecewise conditions do not depend on the dummy summation variable, # therefore we can fold: Sum(Piecewise((e, c), ...), limits) # --> Piecewise((Sum(e, limits), c), ...) newargs = [] for arg in f.args: newexpr = eval_sum(arg.expr, limits) if newexpr is None: return None newargs.append((newexpr, arg.cond)) return f.func(newargs) if f.has(KroneckerDelta) and _has_simple_delta(f, limits[0]): return deltasummation(f, limits) dif = b - a definite = dif.is_Integer # Doing it directly may be faster if there are very few terms. if definite and (dif < 100): return eval_sum_direct(f, (i, a, b)) if isinstance(f, Piecewise): return None # Try to do it symbolically. Even when the number of terms is known, # this can save time when b-a is big. # We should try to transform to partial fractions value = eval_sum_symbolic(f.expand(), (i, a, b)) if value is not None: return value # Do it directly if definite: return eval_sum_direct(f, (i, a, b)) def eval_sum_direct(expr, limits): from sympy.core import Add (i, a, b) = limits dif = b - a return Add([expr.subs(i, a + j) for j in range(dif + 1)]) def eval_sum_symbolic(f, limits): from sympy.functions import harmonic, bernoulli f_orig = f (i, a, b) = limits if not f.has(i): return f(b - a + 1) # Linearity if f.is_Mul: L, R = f.as_two_terms() if not L.has(i): sR = eval_sum_symbolic(R, (i, a, b)) if sR: return LsR if not R.has(i): sL = eval_sum_symbolic(L, (i, a, b)) if sL: return RsL try: f = apart(f, i) # see if it becomes an Add except PolynomialError: pass if f.is_Add: L, R = f.as_two_terms() lrsum = telescopic(L, R, (i, a, b)) if lrsum: return lrsum lsum = eval_sum_symbolic(L, (i, a, b)) rsum = eval_sum_symbolic(R, (i, a, b)) if None not in (lsum, rsum): r = lsum + rsum if not r is S.NaN: return r # Polynomial terms with Faulhaber's formula n = Wild('n') result = f.match(in) if result is not None: n = result[n] if n.is_Integer: if n >= 0: if (b is S.Infinity and not a is S.NegativeInfinity) or \ (a is S.NegativeInfinity and not b is S.Infinity): return S.Infinity return ((bernoulli(n + 1, b + 1) - bernoulli(n + 1, a))/(n + 1)).expand() elif a.is_Integer and a >= 1: if n == -1: return harmonic(b) - harmonic(a - 1) else: return harmonic(b, abs(n)) - harmonic(a - 1, abs(n)) if not (a.has(S.Infinity, S.NegativeInfinity) or b.has(S.Infinity, S.NegativeInfinity)): # Geometric terms c1 = Wild('c1', exclude=[i]) c2 = Wild('c2', exclude=[i]) c3 = Wild('c3', exclude=[i]) wexp = Wild('wexp') # Here we first attempt powsimp on f for easier matching with the # exponential pattern, and attempt expansion on the exponent for easier # matching with the linear pattern. e = f.powsimp().match(c1 * wexp) if e is not None: e_exp = e.pop(wexp).expand().match(c2i + c3) if e_exp is not None: e.update(e_exp) if e is not None: p = (c1c3).subs(e) q = (c1c2).subs(e) r = p(qa - q(b + 1))/(1 - q) l = p(b - a + 1) return Piecewise((l, Eq(q, S.One)), (r, True)) r = gosper_sum(f, (i, a, b)) if isinstance(r, (Mul,Add)): from sympy import ordered, Tuple non_limit = r.free_symbols - Tuple(limits[1:]).free_symbols den = denom(together(r)) den_sym = non_limit & den.free_symbols args = [] for v in ordered(den_sym): try: s = solve(den, v) m = Eq(v, s[0]) if s else S.false if m != False: args.append((Sum(f_orig.subs(m.args), limits).doit(), m)) break except NotImplementedError: continue args.append((r, True)) return Piecewise(args) if not r in (None, S.NaN): return r h = eval_sum_hyper(f_orig, (i, a, b)) if h is not None: return h factored = f_orig.factor() if factored != f_orig: return eval_sum_symbolic(factored, (i, a, b)) def _eval_sum_hyper(f, i, a): """ Returns (res, cond). Sums from a to oo. """ from sympy.functions import hyper from sympy.simplify import hyperexpand, hypersimp, fraction, simplify from sympy.polys.polytools import Poly, factor from sympy.core.numbers import Float if a != 0: return _eval_sum_hyper(f.subs(i, i + a), i, 0) if f.subs(i, 0) == 0: if simplify(f.subs(i, Dummy('i', integer=True, positive=True))) == 0: return S(0), True return _eval_sum_hyper(f.subs(i, i + 1), i, 0) hs = hypersimp(f, i) if hs is None: return None if isinstance(hs, Float): from sympy.simplify.simplify import nsimplify hs = nsimplify(hs) numer, denom = fraction(factor(hs)) top, topl = numer.as_coeff_mul(i) bot, botl = denom.as_coeff_mul(i) ab = [top, bot] factors = [topl, botl] params = [[], []] for k in range(2): for fac in factors[k]: mul = 1 if fac.is_Pow: mul = fac.exp fac = fac.base if not mul.is_Integer: return None p = Poly(fac, i) if p.degree() != 1: return None m, n = p.all_coeffs() ab[k] = mmul params[k] += [n/m]mul # Add "1" to numerator parameters, to account for implicit n! in # hypergeometric series. ap = params[0] + [1] bq = params[1] x = ab[0]/ab[1] h = hyper(ap, bq, x) return f.subs(i, 0)*hyperexpand(h), h.convergence_statement def eval_sum_hyper(f, i_a_b): from sympy.logic.boolalg import And i, a, b = i_a_b if (b - a).is_Integer: # We are never going to do better than doing the sum in the obvious way return None old_sum = Sum(f, (i, a, b)) if b != S.Infinity: if a == S.NegativeInfinity: res = _eval_sum_hyper(f.subs(i, -i), i, -b) if res is not None: return Piecewise(res, (old_sum, True)) else: res1 = _eval_sum_hyper(f, i, a) res2 = _eval_sum_hyper(f, i, b + 1) if res1 is None or res2 is None: return None (res1, cond1), (res2, cond2) = res1, res2 cond = And(cond1, cond2) if cond == False: return None return Piecewise((res1 - res2, cond), (old_sum, True)) if a == S.NegativeInfinity: res1 = _eval_sum_hyper(f.subs(i, -i), i, 1) res2 = _eval_sum_hyper(f, i, 0) if res1 is None or res2 is None: return None res1, cond1 = res1 res2, cond2 = res2 cond = And(cond1, cond2) if cond == False: return None return Piecewise((res1 + res2, cond), (old_sum, True)) # Now b == oo, a != -oo res = _eval_sum_hyper(f, i, a) if res is not None: r, c = res if c == False: if r.is_number: f = f.subs(i, Dummy('i', integer=True, positive=True) + a) if f.is_positive or f.is_zero: return S.Infinity elif f.is_negative: return S.NegativeInfinity return None return Piecewise(res, (old_sum, True))
008a547620a0adc51a337d124bb92e8cd53c67e4ec331ee5bdf0a8786894ca54	""" Expand Hypergeometric (and Meijer G) functions into named special functions. The algorithm for doing this uses a collection of lookup tables of hypergeometric functions, and various of their properties, to expand many hypergeometric functions in terms of special functions. It is based on the following paper: Kelly B. Roach. Meijer G Function Representations. In: Proceedings of the 1997 International Symposium on Symbolic and Algebraic Computation, pages 205-211, New York, 1997. ACM. It is described in great(er) detail in the Sphinx documentation. """ # SUMMARY OF EXTENSIONS FOR MEIJER G FUNCTIONS # # o z*rho G(ap, bq; z) = G(ap + rho, bq + rho; z) # # o denote zd/dz by D # # o It is helpful to keep in mind that ap and bq play essentially symmetric # roles: G(1/z) has slightly altered parameters, with ap and bq interchanged. # # o There are four shift operators: # A_J = b_J - D, J = 1, ..., n # B_J = 1 - a_j + D, J = 1, ..., m # C_J = -b_J + D, J = m+1, ..., q # D_J = a_J - 1 - D, J = n+1, ..., p # # A_J, C_J increment b_J # B_J, D_J decrement a_J # # o The corresponding four inverse-shift operators are defined if there # is no cancellation. Thus e.g. an index a_J (upper or lower) can be # incremented if a_J != b_i for i = 1, ..., q. # # o Order reduction: if b_j - a_i is a non-negative integer, where # j <= m and i > n, the corresponding quotient of gamma functions reduces # to a polynomial. Hence the G function can be expressed using a G-function # of lower order. # Similarly if j > m and i <= n. # # Secondly, there are paired index theorems [Adamchik, The evaluation of # integrals of Bessel functions via G-function identities]. Suppose there # are three parameters a, b, c, where a is an a_i, i <= n, b is a b_j, # j <= m and c is a denominator parameter (i.e. a_i, i > n or b_j, j > m). # Suppose further all three differ by integers. # Then the order can be reduced. # TODO work this out in detail. # # o An index quadruple is called suitable if its order cannot be reduced. # If there exists a sequence of shift operators transforming one index # quadruple into another, we say one is reachable from the other. # # o Deciding if one index quadruple is reachable from another is tricky. For # this reason, we use hand-built routines to match and instantiate formulas. # from __future__ import print_function, division from collections import defaultdict from itertools import product from sympy import SYMPY_DEBUG from sympy.core import (S, Dummy, symbols, sympify, Tuple, expand, I, pi, Mul, EulerGamma, oo, zoo, expand_func, Add, nan, Expr) from sympy.core.compatibility import default_sort_key, range from sympy.core.mod import Mod from sympy.functions import (exp, sqrt, root, log, lowergamma, cos, besseli, gamma, uppergamma, expint, erf, sin, besselj, Ei, Ci, Si, Shi, sinh, cosh, Chi, fresnels, fresnelc, polar_lift, exp_polar, floor, ceiling, rf, factorial, lerchphi, Piecewise, re, elliptic_k, elliptic_e) from sympy.functions.elementary.complexes import polarify, unpolarify from sympy.functions.special.hyper import (hyper, HyperRep_atanh, HyperRep_power1, HyperRep_power2, HyperRep_log1, HyperRep_asin1, HyperRep_asin2, HyperRep_sqrts1, HyperRep_sqrts2, HyperRep_log2, HyperRep_cosasin, HyperRep_sinasin, meijerg) from sympy.polys import poly, Poly from sympy.series import residue from sympy.simplify import simplify from sympy.simplify.powsimp import powdenest from sympy.utilities.iterables import sift # function to define "buckets" def _mod1(x): # TODO see if this can work as Mod(x, 1); this will require # different handling of the "buckets" since these need to # be sorted and that fails when there is a mixture of # integers and expressions with parameters. With the current # Mod behavior, Mod(k, 1) == Mod(1, 1) == 0 if k is an integer. # Although the sorting can be done with Basic.compare, this may # still require different handling of the sorted buckets. if x.is_Number: return Mod(x, 1) c, x = x.as_coeff_Add() return Mod(c, 1) + x # leave add formulae at the top for easy reference def add_formulae(formulae): """ Create our knowledge base. """ from sympy.matrices import Matrix a, b, c, z = symbols('a b c, z', cls=Dummy) def add(ap, bq, res): func = Hyper_Function(ap, bq) formulae.append(Formula(func, z, res, (a, b, c))) def addb(ap, bq, B, C, M): func = Hyper_Function(ap, bq) formulae.append(Formula(func, z, None, (a, b, c), B, C, M)) # Luke, Y. L. (1969), The Special Functions and Their Approximations, # Volume 1, section 6.2 # 0F0 add((), (), exp(z)) # 1F0 add((a, ), (), HyperRep_power1(-a, z)) # 2F1 addb((a, a - S.Half), (2a, ), Matrix([HyperRep_power2(a, z), HyperRep_power2(a + S(1)/2, z)/2]), Matrix([[1, 0]]), Matrix([[(a - S.Half)z/(1 - z), (S.Half - a)z/(1 - z)], [a/(1 - z), a(z - 2)/(1 - z)]])) addb((1, 1), (2, ), Matrix([HyperRep_log1(z), 1]), Matrix([[-1/z, 0]]), Matrix([[0, z/(z - 1)], [0, 0]])) addb((S.Half, 1), (S('3/2'), ), Matrix([HyperRep_atanh(z), 1]), Matrix([[1, 0]]), Matrix([[-S(1)/2, 1/(1 - z)/2], [0, 0]])) addb((S.Half, S.Half), (S('3/2'), ), Matrix([HyperRep_asin1(z), HyperRep_power1(-S(1)/2, z)]), Matrix([[1, 0]]), Matrix([[-S(1)/2, S(1)/2], [0, z/(1 - z)/2]])) addb((a, S.Half + a), (S.Half, ), Matrix([HyperRep_sqrts1(-a, z), -HyperRep_sqrts2(-a - S(1)/2, z)]), Matrix([[1, 0]]), Matrix([[0, -a], [z(-2a - 1)/2/(1 - z), S.Half - z(-2a - 1)/(1 - z)]])) # A. P. Prudnikov, Yu. A. Brychkov and O. I. Marichev (1990). # Integrals and Series: More Special Functions, Vol. 3,. # Gordon and Breach Science Publisher addb([a, -a], [S.Half], Matrix([HyperRep_cosasin(a, z), HyperRep_sinasin(a, z)]), Matrix([[1, 0]]), Matrix([[0, -a], [az/(1 - z), 1/(1 - z)/2]])) addb([1, 1], [3S.Half], Matrix([HyperRep_asin2(z), 1]), Matrix([[1, 0]]), Matrix([[(z - S.Half)/(1 - z), 1/(1 - z)/2], [0, 0]])) # Complete elliptic integrals K(z) and E(z), both a 2F1 function addb([S.Half, S.Half], [S.One], Matrix([elliptic_k(z), elliptic_e(z)]), Matrix([[2/pi, 0]]), Matrix([[-S.Half, -1/(2z-2)], [-S.Half, S.Half]])) addb([-S.Half, S.Half], [S.One], Matrix([elliptic_k(z), elliptic_e(z)]), Matrix([[0, 2/pi]]), Matrix([[-S.Half, -1/(2z-2)], [-S.Half, S.Half]])) # 3F2 addb([-S.Half, 1, 1], [S.Half, 2], Matrix([zHyperRep_atanh(z), HyperRep_log1(z), 1]), Matrix([[-S(2)/3, -S(1)/(3z), S(2)/3]]), Matrix([[S(1)/2, 0, z/(1 - z)/2], [0, 0, z/(z - 1)], [0, 0, 0]])) # actually the formula for 3/2 is much nicer ... addb([-S.Half, 1, 1], [2, 2], Matrix([HyperRep_power1(S(1)/2, z), HyperRep_log2(z), 1]), Matrix([[S(4)/9 - 16/(9z), 4/(3z), 16/(9z)]]), Matrix([[z/2/(z - 1), 0, 0], [1/(2(z - 1)), 0, S.Half], [0, 0, 0]])) # 1F1 addb([1], [b], Matrix([z*(1 - b) exp(z) * lowergamma(b - 1, z), 1]), Matrix([[b - 1, 0]]), Matrix([[1 - b + z, 1], [0, 0]])) addb([a], [2a], Matrix([z(S.Half - a)exp(z/2)besseli(a - S.Half, z/2) gamma(a + S.Half)/4(S.Half - a), z(S.Half - a)exp(z/2)besseli(a + S.Half, z/2) * gamma(a + S.Half)/4*(S.Half - a)]), Matrix([[1, 0]]), Matrix([[z/2, z/2], [z/2, (z/2 - 2a)]])) mz = polar_lift(-1)z addb([a], [a + 1], Matrix([mz(-a)alowergamma(a, mz), aexp(z)]), Matrix([[1, 0]]), Matrix([[-a, 1], [0, z]])) # This one is redundant. add([-S.Half], [S.Half], exp(z) - sqrt(piz)(-I)erf(Isqrt(z))) # Added to get nice results for Laplace transform of Fresnel functions # http://functions.wolfram.com/07.22.03.6437.01 # Basic rule #add([1], [S(3)/4, S(5)/4], # sqrt(pi) * (cos(2sqrt(polar_lift(-1)z))fresnelc(2root(polar_lift(-1)z,4)/sqrt(pi)) + # sin(2sqrt(polar_lift(-1)z))fresnels(2root(polar_lift(-1)z,4)/sqrt(pi))) # / (2root(polar_lift(-1)z,4))) # Manually tuned rule addb([1], [S(3)/4, S(5)/4], Matrix([ sqrt(pi)(Isinh(2sqrt(z))fresnels(2root(z, 4)exp(Ipi/4)/sqrt(pi)) + cosh(2sqrt(z))fresnelc(2root(z, 4)exp(Ipi/4)/sqrt(pi))) * exp(-Ipi/4)/(2root(z, 4)), sqrt(pi)root(z, 4)(sinh(2sqrt(z))fresnelc(2root(z, 4)exp(Ipi/4)/sqrt(pi)) + Icosh(2sqrt(z))fresnels(2root(z, 4)exp(Ipi/4)/sqrt(pi))) exp(-Ipi/4)/2, 1 ]), Matrix([[1, 0, 0]]), Matrix([[-S(1)/4, 1, S(1)/4], [ z, S(1)/4, 0 ], [ 0, 0, 0 ]])) # 2F2 addb([S.Half, a], [S(3)/2, a + 1], Matrix([a/(2a - 1)(-I)sqrt(pi/z)erf(Isqrt(z)), a/(2a - 1)(polar_lift(-1)z)(-a) lowergamma(a, polar_lift(-1)z), a/(2a - 1)exp(z)]), Matrix([[1, -1, 0]]), Matrix([[-S.Half, 0, 1], [0, -a, 1], [0, 0, z]])) # We make a "basis" of four functions instead of three, and give EulerGamma # an extra slot (it could just be a coefficient to 1). The advantage is # that this way Polys will not see multivariate polynomials (it treats # EulerGamma as an indeterminate), which is way* faster. addb([1, 1], [2, 2], Matrix([Ei(z) - log(z), exp(z), 1, EulerGamma]), Matrix([[1/z, 0, 0, -1/z]]), Matrix([[0, 1, -1, 0], [0, z, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0]])) # 0F1 add((), (S.Half, ), cosh(2sqrt(z))) addb([], [b], Matrix([gamma(b)z*((1 - b)/2)besseli(b - 1, 2sqrt(z)), gamma(b)z*(1 - b/2)besseli(b, 2sqrt(z))]), Matrix([[1, 0]]), Matrix([[0, 1], [z, (1 - b)]])) # 0F3 x = 4z*(S(1)/4) def fp(a, z): return besseli(a, x) + besselj(a, x) def fm(a, z): return besseli(a, x) - besselj(a, x) # TODO branching addb([], [S.Half, a, a + S.Half], Matrix([fp(2a - 1, z), fm(2a, z)z*(S(1)/4), fm(2a - 1, z)sqrt(z), fp(2a, z)z(S(3)/4)]) 2*(-2a)gamma(2a)z((1 - 2a)/4), Matrix([[1, 0, 0, 0]]), Matrix([[0, 1, 0, 0], [0, S(1)/2 - a, 1, 0], [0, 0, S(1)/2, 1], [z, 0, 0, 1 - a]])) x = 2(4z)*(S(1)/4)exp_polar(Ipi/4) addb([], [a, a + S.Half, 2a], (2sqrt(polar_lift(-1)z))*(1 - 2a)gamma(2a)*2 Matrix([besselj(2a - 1, x)besseli(2a - 1, x), x(besseli(2a, x)besselj(2a - 1, x) - besseli(2a - 1, x)besselj(2a, x)), x*2besseli(2a, x)besselj(2a, x), x3(besseli(2a, x)besselj(2a - 1, x) + besseli(2a - 1, x)besselj(2a, x))]), Matrix([[1, 0, 0, 0]]), Matrix([[0, S(1)/4, 0, 0], [0, (1 - 2a)/2, -S(1)/2, 0], [0, 0, 1 - 2a, S(1)/4], [-32z, 0, 0, 1 - a]])) # 1F2 addb([a], [a - S.Half, 2a], Matrix([z*(S.Half - a)besseli(a - S.Half, sqrt(z))2, z(1 - a)besseli(a - S.Half, sqrt(z)) besseli(a - S(3)/2, sqrt(z)), z*(S(3)/2 - a)besseli(a - S(3)/2, sqrt(z))2]), Matrix([[-gamma(a + S.Half)2/4*(S.Half - a), 2gamma(a - S.Half)gamma(a + S.Half)/4(1 - a), 0]]), Matrix([[1 - 2a, 1, 0], [z/2, S.Half - a, S.Half], [0, z, 0]])) addb([S.Half], [b, 2 - b], pi(1 - b)/sin(pib)* Matrix([besseli(1 - b, sqrt(z))besseli(b - 1, sqrt(z)), sqrt(z)(besseli(-b, sqrt(z))besseli(b - 1, sqrt(z)) + besseli(1 - b, sqrt(z))besseli(b, sqrt(z))), besseli(-b, sqrt(z))besseli(b, sqrt(z))]), Matrix([[1, 0, 0]]), Matrix([[b - 1, S(1)/2, 0], [z, 0, z], [0, S(1)/2, -b]])) addb([S(1)/2], [S(3)/2, S(3)/2], Matrix([Shi(2sqrt(z))/2/sqrt(z), sinh(2sqrt(z))/2/sqrt(z), cosh(2sqrt(z))]), Matrix([[1, 0, 0]]), Matrix([[-S.Half, S.Half, 0], [0, -S.Half, S.Half], [0, 2z, 0]])) # FresnelS # Basic rule #add([S(3)/4], [S(3)/2,S(7)/4], 6fresnels( exp(piI/4)root(z,4)2/sqrt(pi) ) / ( pi (exp(piI/4)root(z,4)2/sqrt(pi))3 ) ) # Manually tuned rule addb([S(3)/4], [S(3)/2, S(7)/4], Matrix( [ fresnels( exp( piI/4)root( z, 4)2/sqrt( pi) ) / ( pi * (exp(piI/4)root(z, 4)2/sqrt(pi))3 ), sinh(2sqrt(z))/sqrt(z), cosh(2sqrt(z)) ]), Matrix([[6, 0, 0]]), Matrix([[-S(3)/4, S(1)/16, 0], [ 0, -S(1)/2, 1], [ 0, z, 0]])) # FresnelC # Basic rule #add([S(1)/4], [S(1)/2,S(5)/4], fresnelc( exp(piI/4)root(z,4)2/sqrt(pi) ) / ( exp(piI/4)root(z,4)2/sqrt(pi) ) ) # Manually tuned rule addb([S(1)/4], [S(1)/2, S(5)/4], Matrix( [ sqrt( pi)exp( -Ipi/4)fresnelc( 2root(z, 4)exp(Ipi/4)/sqrt(pi))/(2root(z, 4)), cosh(2sqrt(z)), sinh(2sqrt(z))sqrt(z) ]), Matrix([[1, 0, 0]]), Matrix([[-S(1)/4, S(1)/4, 0 ], [ 0, 0, 1 ], [ 0, z, S(1)/2]])) # 2F3 # XXX with this five-parameter formula is pretty slow with the current # Formula.find_instantiations (creates 2!3!3(2+3) ~ 3000 # instantiations ... But it's not too bad. addb([a, a + S.Half], [2a, b, 2a - b + 1], gamma(b)gamma(2a - b + 1) (sqrt(z)/2)*(1 - 2a) * Matrix([besseli(b - 1, sqrt(z))besseli(2a - b, sqrt(z)), sqrt(z)besseli(b, sqrt(z))besseli(2a - b, sqrt(z)), sqrt(z)besseli(b - 1, sqrt(z))besseli(2a - b + 1, sqrt(z)), besseli(b, sqrt(z))besseli(2a - b + 1, sqrt(z))]), Matrix([[1, 0, 0, 0]]), Matrix([[0, S(1)/2, S(1)/2, 0], [z/2, 1 - b, 0, z/2], [z/2, 0, b - 2a, z/2], [0, S(1)/2, S(1)/2, -2a]])) # (C/f above comment about eulergamma in the basis). addb([1, 1], [2, 2, S(3)/2], Matrix([Chi(2sqrt(z)) - log(2sqrt(z)), cosh(2sqrt(z)), sqrt(z)sinh(2sqrt(z)), 1, EulerGamma]), Matrix([[1/z, 0, 0, 0, -1/z]]), Matrix([[0, S(1)/2, 0, -S(1)/2, 0], [0, 0, 1, 0, 0], [0, z, S(1)/2, 0, 0], [0, 0, 0, 0, 0], [0, 0, 0, 0, 0]])) # 3F3 # This is rule: http://functions.wolfram.com/07.31.03.0134.01 # Initial reason to add it was a nice solution for # integrate(erf(az)/z*2, z) and same for erfc and erfi. # Basic rule # add([1, 1, a], [2, 2, a+1], (a/(z(a-1)*2)) # (1 - (-z)*(1-a) (gamma(a) - uppergamma(a,-z)) # - (a-1) * (EulerGamma + uppergamma(0,-z) + log(-z)) # - exp(z))) # Manually tuned rule addb([1, 1, a], [2, 2, a+1], Matrix([a(log(-z) + expint(1, -z) + EulerGamma)/(z(a*2 - 2a + 1)), a(-z)(-a)(gamma(a) - uppergamma(a, -z))/(a - 1)*2, aexp(z)/(a*2 - 2a + 1), a/(z(a2 - 2a + 1))]), Matrix([[1-a, 1, -1/z, 1]]), Matrix([[-1,0,-1/z,1], [0,-a,1,0], [0,0,z,0], [0,0,0,-1]])) def add_meijerg_formulae(formulae): from sympy.matrices import Matrix a, b, c, z = list(map(Dummy, 'abcz')) rho = Dummy('rho') def add(an, ap, bm, bq, B, C, M, matcher): formulae.append(MeijerFormula(an, ap, bm, bq, z, [a, b, c, rho], B, C, M, matcher)) def detect_uppergamma(func): x = func.an[0] y, z = func.bm swapped = False if not _mod1((x - y).simplify()): swapped = True (y, z) = (z, y) if _mod1((x - z).simplify()) or x - z > 0: return None l = [y, x] if swapped: l = [x, y] return {rho: y, a: x - y}, G_Function([x], [], l, []) add([a + rho], [], [rho, a + rho], [], Matrix([gamma(1 - a)zrhoexp(z)uppergamma(a, z), gamma(1 - a)z*(a + rho)]), Matrix([[1, 0]]), Matrix([[rho + z, -1], [0, a + rho]]), detect_uppergamma) def detect_3113(func): """http://functions.wolfram.com/07.34.03.0984.01""" x = func.an[0] u, v, w = func.bm if _mod1((u - v).simplify()) == 0: if _mod1((v - w).simplify()) == 0: return sig = (S(1)/2, S(1)/2, S(0)) x1, x2, y = u, v, w else: if _mod1((x - u).simplify()) == 0: sig = (S(1)/2, S(0), S(1)/2) x1, y, x2 = u, v, w else: sig = (S(0), S(1)/2, S(1)/2) y, x1, x2 = u, v, w if (_mod1((x - x1).simplify()) != 0 or _mod1((x - x2).simplify()) != 0 or _mod1((x - y).simplify()) != S(1)/2 or x - x1 > 0 or x - x2 > 0): return return {a: x}, G_Function([x], [], [x - S(1)/2 + t for t in sig], []) s = sin(2sqrt(z)) c_ = cos(2sqrt(z)) S_ = Si(2sqrt(z)) - pi/2 C = Ci(2sqrt(z)) add([a], [], [a, a, a - S(1)/2], [], Matrix([sqrt(pi)z*(a - S(1)/2)(c_S_ - sC), sqrt(pi)za(sS_ + c_C), sqrt(pi)za]), Matrix([[-2, 0, 0]]), Matrix([[a - S(1)/2, -1, 0], [z, a, S(1)/2], [0, 0, a]]), detect_3113) def make_simp(z): """ Create a function that simplifies rational functions in ``z``. """ def simp(expr): """ Efficiently simplify the rational function ``expr``. """ numer, denom = expr.as_numer_denom() numer = numer.expand() # denom = denom.expand() # is this needed? c, numer, denom = poly(numer, z).cancel(poly(denom, z)) return c numer.as_expr() / denom.as_expr() return simp def debug(args): if SYMPY_DEBUG: for a in args: print(a, end="") print() class Hyper_Function(Expr): """ A generalized hypergeometric function. """ def __new__(cls, ap, bq): obj = super(Hyper_Function, cls).__new__(cls) obj.ap = Tuple(list(map(expand, ap))) obj.bq = Tuple(list(map(expand, bq))) return obj @property def args(self): return (self.ap, self.bq) @property def sizes(self): return (len(self.ap), len(self.bq)) @property def gamma(self): """ Number of upper parameters that are negative integers This is a transformation invariant. """ return sum(bool(x.is_integer and x.is_negative) for x in self.ap) def _hashable_content(self): return super(Hyper_Function, self)._hashable_content() + (self.ap, self.bq) def __call__(self, arg): return hyper(self.ap, self.bq, arg) def build_invariants(self): """ Compute the invariant vector. The invariant vector is: (gamma, ((s1, n1), ..., (sk, nk)), ((t1, m1), ..., (tr, mr))) where gamma is the number of integer a < 0, s1 < ... < sk nl is the number of parameters a_i congruent to sl mod 1 t1 < ... < tr ml is the number of parameters b_i congruent to tl mod 1 If the index pair contains parameters, then this is not truly an invariant, since the parameters cannot be sorted uniquely mod1. Examples ======== >>> from sympy.simplify.hyperexpand import Hyper_Function >>> from sympy import S >>> ap = (S(1)/2, S(1)/3, S(-1)/2, -2) >>> bq = (1, 2) Here gamma = 1, k = 3, s1 = 0, s2 = 1/3, s3 = 1/2 n1 = 1, n2 = 1, n2 = 2 r = 1, t1 = 0 m1 = 2: >>> Hyper_Function(ap, bq).build_invariants() (1, ((0, 1), (1/3, 1), (1/2, 2)), ((0, 2),)) """ abuckets, bbuckets = sift(self.ap, _mod1), sift(self.bq, _mod1) def tr(bucket): bucket = list(bucket.items()) if not any(isinstance(x[0], Mod) for x in bucket): bucket.sort(key=lambda x: default_sort_key(x[0])) bucket = tuple([(mod, len(values)) for mod, values in bucket if values]) return bucket return (self.gamma, tr(abuckets), tr(bbuckets)) def difficulty(self, func): """ Estimate how many steps it takes to reach ``func`` from self. Return -1 if impossible. """ if self.gamma != func.gamma: return -1 oabuckets, obbuckets, abuckets, bbuckets = [sift(params, _mod1) for params in (self.ap, self.bq, func.ap, func.bq)] diff = 0 for bucket, obucket in [(abuckets, oabuckets), (bbuckets, obbuckets)]: for mod in set(list(bucket.keys()) + list(obucket.keys())): if (not mod in bucket) or (not mod in obucket) \ or len(bucket[mod]) != len(obucket[mod]): return -1 l1 = list(bucket[mod]) l2 = list(obucket[mod]) l1.sort() l2.sort() for i, j in zip(l1, l2): diff += abs(i - j) return diff def _is_suitable_origin(self): """ Decide if ``self`` is a suitable origin. A function is a suitable origin iff: none of the ai equals bj + n, with n a non-negative integer * none of the ai is zero * none of the bj is a non-positive integer Note that this gives meaningful results only when none of the indices are symbolic. """ for a in self.ap: for b in self.bq: if (a - b).is_integer and (a - b).is_negative is False: return False for a in self.ap: if a == 0: return False for b in self.bq: if b.is_integer and b.is_nonpositive: return False return True class G_Function(Expr): """ A Meijer G-function. """ def __new__(cls, an, ap, bm, bq): obj = super(G_Function, cls).__new__(cls) obj.an = Tuple(list(map(expand, an))) obj.ap = Tuple(list(map(expand, ap))) obj.bm = Tuple(list(map(expand, bm))) obj.bq = Tuple(list(map(expand, bq))) return obj @property def args(self): return (self.an, self.ap, self.bm, self.bq) def _hashable_content(self): return super(G_Function, self)._hashable_content() + self.args def __call__(self, z): return meijerg(self.an, self.ap, self.bm, self.bq, z) def compute_buckets(self): """ Compute buckets for the fours sets of parameters. We guarantee that any two equal Mod objects returned are actually the same, and that the buckets are sorted by real part (an and bq descendending, bm and ap ascending). Examples ======== >>> from sympy.simplify.hyperexpand import G_Function >>> from sympy.abc import y >>> from sympy import S, symbols >>> a, b = [1, 3, 2, S(3)/2], [1 + y, y, 2, y + 3] >>> G_Function(a, b, [2], [y]).compute_buckets() ({0: [3, 2, 1], 1/2: [3/2]}, {0: [2], y: [y, y + 1, y + 3]}, {0: [2]}, {y: [y]}) """ dicts = pan, pap, pbm, pbq = [defaultdict(list) for i in range(4)] for dic, lis in zip(dicts, (self.an, self.ap, self.bm, self.bq)): for x in lis: dic[_mod1(x)].append(x) for dic, flip in zip(dicts, (True, False, False, True)): for m, items in dic.items(): x0 = items[0] items.sort(key=lambda x: x - x0, reverse=flip) dic[m] = items return tuple([dict(w) for w in dicts]) @property def signature(self): return (len(self.an), len(self.ap), len(self.bm), len(self.bq)) # Dummy variable. _x = Dummy('x') class Formula(object): """ This class represents hypergeometric formulae. Its data members are: - z, the argument - closed_form, the closed form expression - symbols, the free symbols (parameters) in the formula - func, the function - B, C, M (see _compute_basis) Examples ======== >>> from sympy.abc import a, b, z >>> from sympy.simplify.hyperexpand import Formula, Hyper_Function >>> func = Hyper_Function((a/2, a/3 + b, (1+a)/2), (a, b, (a+b)/7)) >>> f = Formula(func, z, None, [a, b]) """ def _compute_basis(self, closed_form): """ Compute a set of functions B=(f1, ..., fn), a nxn matrix M and a 1xn matrix C such that: closed_form = C B z d/dz B = M B. """ from sympy.matrices import Matrix, eye, zeros afactors = [_x + a for a in self.func.ap] bfactors = [_x + b - 1 for b in self.func.bq] expr = _xMul(bfactors) - self.zMul(afactors) poly = Poly(expr, _x) n = poly.degree() - 1 b = [closed_form] for _ in range(n): b.append(self.zb[-1].diff(self.z)) self.B = Matrix(b) self.C = Matrix([[1] + [0]n]) m = eye(n) m = m.col_insert(0, zeros(n, 1)) l = poly.all_coeffs()[1:] l.reverse() self.M = m.row_insert(n, -Matrix([l])/poly.all_coeffs()[0]) def __init__(self, func, z, res, symbols, B=None, C=None, M=None): z = sympify(z) res = sympify(res) symbols = [x for x in sympify(symbols) if func.has(x)] self.z = z self.symbols = symbols self.B = B self.C = C self.M = M self.func = func # TODO with symbolic parameters, it could be advantageous # (for prettier answers) to compute a basis only after # instantiation if res is not None: self._compute_basis(res) @property def closed_form(self): return (self.Cself.B)[0] def find_instantiations(self, func): """ Find substitutions of the free symbols that match ``func``. Return the substitution dictionaries as a list. Note that the returned instantiations need not actually match, or be valid! """ from sympy.solvers import solve ap = func.ap bq = func.bq if len(ap) != len(self.func.ap) or len(bq) != len(self.func.bq): raise TypeError('Cannot instantiate other number of parameters') symbol_values = [] for a in self.symbols: if a in self.func.ap.args: symbol_values.append(ap) elif a in self.func.bq.args: symbol_values.append(bq) else: raise ValueError("At least one of the parameters of the " "formula must be equal to %s" % (a,)) base_repl = [dict(list(zip(self.symbols, values))) for values in product(symbol_values)] abuckets, bbuckets = [sift(params, _mod1) for params in [ap, bq]] a_inv, b_inv = [dict((a, len(vals)) for a, vals in bucket.items()) for bucket in [abuckets, bbuckets]] critical_values = [[0] for _ in self.symbols] result = [] _n = Dummy() for repl in base_repl: symb_a, symb_b = [sift(params, lambda x: _mod1(x.xreplace(repl))) for params in [self.func.ap, self.func.bq]] for bucket, obucket in [(abuckets, symb_a), (bbuckets, symb_b)]: for mod in set(list(bucket.keys()) + list(obucket.keys())): if (not mod in bucket) or (not mod in obucket) \ or len(bucket[mod]) != len(obucket[mod]): break for a, vals in zip(self.symbols, critical_values): if repl[a].free_symbols: continue exprs = [expr for expr in obucket[mod] if expr.has(a)] repl0 = repl.copy() repl0[a] += _n for expr in exprs: for target in bucket[mod]: n0, = solve(expr.xreplace(repl0) - target, _n) if n0.free_symbols: raise ValueError("Value should not be true") vals.append(n0) else: values = [] for a, vals in zip(self.symbols, critical_values): a0 = repl[a] min_ = floor(min(vals)) max_ = ceiling(max(vals)) values.append([a0 + n for n in range(min_, max_ + 1)]) result.extend(dict(list(zip(self.symbols, l))) for l in product(values)) return result class FormulaCollection(object): """ A collection of formulae to use as origins. """ def __init__(self): """ Doing this globally at module init time is a pain ... """ self.symbolic_formulae = {} self.concrete_formulae = {} self.formulae = [] add_formulae(self.formulae) # Now process the formulae into a helpful form. # These dicts are indexed by (p, q). for f in self.formulae: sizes = f.func.sizes if len(f.symbols) > 0: self.symbolic_formulae.setdefault(sizes, []).append(f) else: inv = f.func.build_invariants() self.concrete_formulae.setdefault(sizes, {})[inv] = f def lookup_origin(self, func): """ Given the suitable target ``func``, try to find an origin in our knowledge base. Examples ======== >>> from sympy.simplify.hyperexpand import (FormulaCollection, ... Hyper_Function) >>> f = FormulaCollection() >>> f.lookup_origin(Hyper_Function((), ())).closed_form exp(_z) >>> f.lookup_origin(Hyper_Function([1], ())).closed_form HyperRep_power1(-1, _z) >>> from sympy import S >>> i = Hyper_Function([S('1/4'), S('3/4 + 4')], [S.Half]) >>> f.lookup_origin(i).closed_form HyperRep_sqrts1(-1/4, _z) """ inv = func.build_invariants() sizes = func.sizes if sizes in self.concrete_formulae and \ inv in self.concrete_formulae[sizes]: return self.concrete_formulae[sizes][inv] # We don't have a concrete formula. Try to instantiate. if not sizes in self.symbolic_formulae: return None # Too bad... possible = [] for f in self.symbolic_formulae[sizes]: repls = f.find_instantiations(func) for repl in repls: func2 = f.func.xreplace(repl) if not func2._is_suitable_origin(): continue diff = func2.difficulty(func) if diff == -1: continue possible.append((diff, repl, f, func2)) # find the nearest origin possible.sort(key=lambda x: x[0]) for _, repl, f, func2 in possible: f2 = Formula(func2, f.z, None, [], f.B.subs(repl), f.C.subs(repl), f.M.subs(repl)) if not any(e.has(S.NaN, oo, -oo, zoo) for e in [f2.B, f2.M, f2.C]): return f2 else: return None class MeijerFormula(object): """ This class represents a Meijer G-function formula. Its data members are: - z, the argument - symbols, the free symbols (parameters) in the formula - func, the function - B, C, M (c/f ordinary Formula) """ def __init__(self, an, ap, bm, bq, z, symbols, B, C, M, matcher): an, ap, bm, bq = [Tuple(list(map(expand, w))) for w in [an, ap, bm, bq]] self.func = G_Function(an, ap, bm, bq) self.z = z self.symbols = symbols self._matcher = matcher self.B = B self.C = C self.M = M @property def closed_form(self): return (self.Cself.B)[0] def try_instantiate(self, func): """ Try to instantiate the current formula to (almost) match func. This uses the _matcher passed on init. """ if func.signature != self.func.signature: return None res = self._matcher(func) if res is not None: subs, newfunc = res return MeijerFormula(newfunc.an, newfunc.ap, newfunc.bm, newfunc.bq, self.z, [], self.B.subs(subs), self.C.subs(subs), self.M.subs(subs), None) class MeijerFormulaCollection(object): """ This class holds a collection of meijer g formulae. """ def __init__(self): formulae = [] add_meijerg_formulae(formulae) self.formulae = defaultdict(list) for formula in formulae: self.formulae[formula.func.signature].append(formula) self.formulae = dict(self.formulae) def lookup_origin(self, func): """ Try to find a formula that matches func. """ if not func.signature in self.formulae: return None for formula in self.formulae[func.signature]: res = formula.try_instantiate(func) if res is not None: return res class Operator(object): """ Base class for operators to be applied to our functions. These operators are differential operators. They are by convention expressed in the variable D = zd/dz (although this base class does not actually care). Note that when the operator is applied to an object, we typically do not blindly differentiate but instead use a different representation of the zd/dz operator (see make_derivative_operator). To subclass from this, define a __init__ method that initializes a self._poly variable. This variable stores a polynomial. By convention the generator is zd/dz, and acts to the right of all coefficients. Thus this poly x*2 + 2zx + 1 represents the differential operator (zd/dz)*2 + 2z*2d/dz. This class is used only in the implementation of the hypergeometric function expansion algorithm. """ def apply(self, obj, op): """ Apply ``self`` to the object ``obj``, where the generator is ``op``. Examples ======== >>> from sympy.simplify.hyperexpand import Operator >>> from sympy.polys.polytools import Poly >>> from sympy.abc import x, y, z >>> op = Operator() >>> op._poly = Poly(x*2 + zx + y, x) >>> op.apply(z*7, lambda f: f.diff(z)) yz*7 + 7z*7 + 42z*5 """ coeffs = self._poly.all_coeffs() coeffs.reverse() diffs = [obj] for c in coeffs[1:]: diffs.append(op(diffs[-1])) r = coeffs[0]diffs[0] for c, d in zip(coeffs[1:], diffs[1:]): r += cd return r class MultOperator(Operator): """ Simply multiply by a "constant" """ def __init__(self, p): self._poly = Poly(p, _x) class ShiftA(Operator): """ Increment an upper index. """ def __init__(self, ai): ai = sympify(ai) if ai == 0: raise ValueError('Cannot increment zero upper index.') self._poly = Poly(_x/ai + 1, _x) def __str__(self): return '<Increment upper %s.>' % (1/self._poly.all_coeffs()[0]) class ShiftB(Operator): """ Decrement a lower index. """ def __init__(self, bi): bi = sympify(bi) if bi == 1: raise ValueError('Cannot decrement unit lower index.') self._poly = Poly(_x/(bi - 1) + 1, _x) def __str__(self): return '<Decrement lower %s.>' % (1/self._poly.all_coeffs()[0] + 1) class UnShiftA(Operator): """ Decrement an upper index. """ def __init__(self, ap, bq, i, z): """ Note: i counts from zero! """ ap, bq, i = list(map(sympify, [ap, bq, i])) self._ap = ap self._bq = bq self._i = i ap = list(ap) bq = list(bq) ai = ap.pop(i) - 1 if ai == 0: raise ValueError('Cannot decrement unit upper index.') m = Poly(zai, _x) for a in ap: m = Poly(_x + a, _x) A = Dummy('A') n = D = Poly(aiA - ai, A) for b in bq: n = (D + b - 1) b0 = -n.nth(0) if b0 == 0: raise ValueError('Cannot decrement upper index: ' 'cancels with lower') n = Poly(Poly(n.all_coeffs()[:-1], A).as_expr().subs(A, _x/ai + 1), _x) self._poly = Poly((n - m)/b0, _x) def __str__(self): return '<Decrement upper index #%s of %s, %s.>' % (self._i, self._ap, self._bq) class UnShiftB(Operator): """ Increment a lower index. """ def __init__(self, ap, bq, i, z): """ Note: i counts from zero! """ ap, bq, i = list(map(sympify, [ap, bq, i])) self._ap = ap self._bq = bq self._i = i ap = list(ap) bq = list(bq) bi = bq.pop(i) + 1 if bi == 0: raise ValueError('Cannot increment -1 lower index.') m = Poly(_x(bi - 1), _x) for b in bq: m = Poly(_x + b - 1, _x) B = Dummy('B') D = Poly((bi - 1)B - bi + 1, B) n = Poly(z, B) for a in ap: n = (D + a) b0 = n.nth(0) if b0 == 0: raise ValueError('Cannot increment index: cancels with upper') n = Poly(Poly(n.all_coeffs()[:-1], B).as_expr().subs( B, _x/(bi - 1) + 1), _x) self._poly = Poly((m - n)/b0, _x) def __str__(self): return '<Increment lower index #%s of %s, %s.>' % (self._i, self._ap, self._bq) class MeijerShiftA(Operator): """ Increment an upper b index. """ def __init__(self, bi): bi = sympify(bi) self._poly = Poly(bi - _x, _x) def __str__(self): return '<Increment upper b=%s.>' % (self._poly.all_coeffs()[1]) class MeijerShiftB(Operator): """ Decrement an upper a index. """ def __init__(self, bi): bi = sympify(bi) self._poly = Poly(1 - bi + _x, _x) def __str__(self): return '<Decrement upper a=%s.>' % (1 - self._poly.all_coeffs()[1]) class MeijerShiftC(Operator): """ Increment a lower b index. """ def __init__(self, bi): bi = sympify(bi) self._poly = Poly(-bi + _x, _x) def __str__(self): return '<Increment lower b=%s.>' % (-self._poly.all_coeffs()[1]) class MeijerShiftD(Operator): """ Decrement a lower a index. """ def __init__(self, bi): bi = sympify(bi) self._poly = Poly(bi - 1 - _x, _x) def __str__(self): return '<Decrement lower a=%s.>' % (self._poly.all_coeffs()[1] + 1) class MeijerUnShiftA(Operator): """ Decrement an upper b index. """ def __init__(self, an, ap, bm, bq, i, z): """ Note: i counts from zero! """ an, ap, bm, bq, i = list(map(sympify, [an, ap, bm, bq, i])) self._an = an self._ap = ap self._bm = bm self._bq = bq self._i = i an = list(an) ap = list(ap) bm = list(bm) bq = list(bq) bi = bm.pop(i) - 1 m = Poly(1, _x) for b in bm: m = Poly(b - _x, _x) for b in bq: m = Poly(_x - b, _x) A = Dummy('A') D = Poly(bi - A, A) n = Poly(z, A) for a in an: n = (D + 1 - a) for a in ap: n = (-D + a - 1) b0 = n.nth(0) if b0 == 0: raise ValueError('Cannot decrement upper b index (cancels)') n = Poly(Poly(n.all_coeffs()[:-1], A).as_expr().subs(A, bi - _x), _x) self._poly = Poly((m - n)/b0, _x) def __str__(self): return '<Decrement upper b index #%s of %s, %s, %s, %s.>' % (self._i, self._an, self._ap, self._bm, self._bq) class MeijerUnShiftB(Operator): """ Increment an upper a index. """ def __init__(self, an, ap, bm, bq, i, z): """ Note: i counts from zero! """ an, ap, bm, bq, i = list(map(sympify, [an, ap, bm, bq, i])) self._an = an self._ap = ap self._bm = bm self._bq = bq self._i = i an = list(an) ap = list(ap) bm = list(bm) bq = list(bq) ai = an.pop(i) + 1 m = Poly(z, _x) for a in an: m = Poly(1 - a + _x, _x) for a in ap: m = Poly(a - 1 - _x, _x) B = Dummy('B') D = Poly(B + ai - 1, B) n = Poly(1, B) for b in bm: n = (-D + b) for b in bq: n = (D - b) b0 = n.nth(0) if b0 == 0: raise ValueError('Cannot increment upper a index (cancels)') n = Poly(Poly(n.all_coeffs()[:-1], B).as_expr().subs( B, 1 - ai + _x), _x) self._poly = Poly((m - n)/b0, _x) def __str__(self): return '<Increment upper a index #%s of %s, %s, %s, %s.>' % (self._i, self._an, self._ap, self._bm, self._bq) class MeijerUnShiftC(Operator): """ Decrement a lower b index. """ # XXX this is "essentially" the same as MeijerUnShiftA. This "essentially" # can be made rigorous using the functional equation G(1/z) = G'(z), # where G' denotes a G function of slightly altered parameters. # However, sorting out the details seems harder than just coding it # again. def __init__(self, an, ap, bm, bq, i, z): """ Note: i counts from zero! """ an, ap, bm, bq, i = list(map(sympify, [an, ap, bm, bq, i])) self._an = an self._ap = ap self._bm = bm self._bq = bq self._i = i an = list(an) ap = list(ap) bm = list(bm) bq = list(bq) bi = bq.pop(i) - 1 m = Poly(1, _x) for b in bm: m = Poly(b - _x, _x) for b in bq: m = Poly(_x - b, _x) C = Dummy('C') D = Poly(bi + C, C) n = Poly(z, C) for a in an: n = (D + 1 - a) for a in ap: n = (-D + a - 1) b0 = n.nth(0) if b0 == 0: raise ValueError('Cannot decrement lower b index (cancels)') n = Poly(Poly(n.all_coeffs()[:-1], C).as_expr().subs(C, _x - bi), _x) self._poly = Poly((m - n)/b0, _x) def __str__(self): return '<Decrement lower b index #%s of %s, %s, %s, %s.>' % (self._i, self._an, self._ap, self._bm, self._bq) class MeijerUnShiftD(Operator): """ Increment a lower a index. """ # XXX This is essentially the same as MeijerUnShiftA. # See comment at MeijerUnShiftC. def __init__(self, an, ap, bm, bq, i, z): """ Note: i counts from zero! """ an, ap, bm, bq, i = list(map(sympify, [an, ap, bm, bq, i])) self._an = an self._ap = ap self._bm = bm self._bq = bq self._i = i an = list(an) ap = list(ap) bm = list(bm) bq = list(bq) ai = ap.pop(i) + 1 m = Poly(z, _x) for a in an: m = Poly(1 - a + _x, _x) for a in ap: m = Poly(a - 1 - _x, _x) B = Dummy('B') # - this is the shift operator `D_I` D = Poly(ai - 1 - B, B) n = Poly(1, B) for b in bm: n = (-D + b) for b in bq: n = (D - b) b0 = n.nth(0) if b0 == 0: raise ValueError('Cannot increment lower a index (cancels)') n = Poly(Poly(n.all_coeffs()[:-1], B).as_expr().subs( B, ai - 1 - _x), _x) self._poly = Poly((m - n)/b0, _x) def __str__(self): return '<Increment lower a index #%s of %s, %s, %s, %s.>' % (self._i, self._an, self._ap, self._bm, self._bq) class ReduceOrder(Operator): """ Reduce Order by cancelling an upper and a lower index. """ def __new__(cls, ai, bj): """ For convenience if reduction is not possible, return None. """ ai = sympify(ai) bj = sympify(bj) n = ai - bj if not n.is_Integer or n < 0: return None if bj.is_integer and bj.is_nonpositive: return None expr = Operator.__new__(cls) p = S(1) for k in range(n): p = (_x + bj + k)/(bj + k) expr._poly = Poly(p, _x) expr._a = ai expr._b = bj return expr @classmethod def _meijer(cls, b, a, sign): """ Cancel b + signs and a + signs This is for meijer G functions. """ b = sympify(b) a = sympify(a) n = b - a if n.is_negative or not n.is_Integer: return None expr = Operator.__new__(cls) p = S(1) for k in range(n): p = (sign_x + a + k) expr._poly = Poly(p, _x) if sign == -1: expr._a = b expr._b = a else: expr._b = Add(1, a - 1, evaluate=False) expr._a = Add(1, b - 1, evaluate=False) return expr @classmethod def meijer_minus(cls, b, a): return cls._meijer(b, a, -1) @classmethod def meijer_plus(cls, a, b): return cls._meijer(1 - a, 1 - b, 1) def __str__(self): return '<Reduce order by cancelling upper %s with lower %s.>' % \ (self._a, self._b) def _reduce_order(ap, bq, gen, key): """ Order reduction algorithm used in Hypergeometric and Meijer G """ ap = list(ap) bq = list(bq) ap.sort(key=key) bq.sort(key=key) nap = [] # we will edit bq in place operators = [] for a in ap: op = None for i in range(len(bq)): op = gen(a, bq[i]) if op is not None: bq.pop(i) break if op is None: nap.append(a) else: operators.append(op) return nap, bq, operators def reduce_order(func): """ Given the hypergeometric function ``func``, find a sequence of operators to reduces order as much as possible. Return (newfunc, [operators]), where applying the operators to the hypergeometric function newfunc yields func. Examples ======== >>> from sympy.simplify.hyperexpand import reduce_order, Hyper_Function >>> reduce_order(Hyper_Function((1, 2), (3, 4))) (Hyper_Function((1, 2), (3, 4)), []) >>> reduce_order(Hyper_Function((1,), (1,))) (Hyper_Function((), ()), [<Reduce order by cancelling upper 1 with lower 1.>]) >>> reduce_order(Hyper_Function((2, 4), (3, 3))) (Hyper_Function((2,), (3,)), [<Reduce order by cancelling upper 4 with lower 3.>]) """ nap, nbq, operators = _reduce_order(func.ap, func.bq, ReduceOrder, default_sort_key) return Hyper_Function(Tuple(nap), Tuple(nbq)), operators def reduce_order_meijer(func): """ Given the Meijer G function parameters, ``func``, find a sequence of operators that reduces order as much as possible. Return newfunc, [operators]. Examples ======== >>> from sympy.simplify.hyperexpand import (reduce_order_meijer, ... G_Function) >>> reduce_order_meijer(G_Function([3, 4], [5, 6], [3, 4], [1, 2]))[0] G_Function((4, 3), (5, 6), (3, 4), (2, 1)) >>> reduce_order_meijer(G_Function([3, 4], [5, 6], [3, 4], [1, 8]))[0] G_Function((3,), (5, 6), (3, 4), (1,)) >>> reduce_order_meijer(G_Function([3, 4], [5, 6], [7, 5], [1, 5]))[0] G_Function((3,), (), (), (1,)) >>> reduce_order_meijer(G_Function([3, 4], [5, 6], [7, 5], [5, 3]))[0] G_Function((), (), (), ()) """ nan, nbq, ops1 = _reduce_order(func.an, func.bq, ReduceOrder.meijer_plus, lambda x: default_sort_key(-x)) nbm, nap, ops2 = _reduce_order(func.bm, func.ap, ReduceOrder.meijer_minus, default_sort_key) return G_Function(nan, nap, nbm, nbq), ops1 + ops2 def make_derivative_operator(M, z): """ Create a derivative operator, to be passed to Operator.apply. """ def doit(C): r = zC.diff(z) + CM r = r.applyfunc(make_simp(z)) return r return doit def apply_operators(obj, ops, op): """ Apply the list of operators ``ops`` to object ``obj``, substituting ``op`` for the generator. """ res = obj for o in reversed(ops): res = o.apply(res, op) return res def devise_plan(target, origin, z): """ Devise a plan (consisting of shift and un-shift operators) to be applied to the hypergeometric function ``target`` to yield ``origin``. Returns a list of operators. Examples ======== >>> from sympy.simplify.hyperexpand import devise_plan, Hyper_Function >>> from sympy.abc import z Nothing to do: >>> devise_plan(Hyper_Function((1, 2), ()), Hyper_Function((1, 2), ()), z) [] >>> devise_plan(Hyper_Function((), (1, 2)), Hyper_Function((), (1, 2)), z) [] Very simple plans: >>> devise_plan(Hyper_Function((2,), ()), Hyper_Function((1,), ()), z) [<Increment upper 1.>] >>> devise_plan(Hyper_Function((), (2,)), Hyper_Function((), (1,)), z) [<Increment lower index #0 of [], [1].>] Several buckets: >>> from sympy import S >>> devise_plan(Hyper_Function((1, S.Half), ()), ... Hyper_Function((2, S('3/2')), ()), z) #doctest: +NORMALIZE_WHITESPACE [<Decrement upper index #0 of [3/2, 1], [].>, <Decrement upper index #0 of [2, 3/2], [].>] A slightly more complicated plan: >>> devise_plan(Hyper_Function((1, 3), ()), Hyper_Function((2, 2), ()), z) [<Increment upper 2.>, <Decrement upper index #0 of [2, 2], [].>] Another more complicated plan: (note that the ap have to be shifted first!) >>> devise_plan(Hyper_Function((1, -1), (2,)), Hyper_Function((3, -2), (4,)), z) [<Decrement lower 3.>, <Decrement lower 4.>, <Decrement upper index #1 of [-1, 2], [4].>, <Decrement upper index #1 of [-1, 3], [4].>, <Increment upper -2.>] """ abuckets, bbuckets, nabuckets, nbbuckets = [sift(params, _mod1) for params in (target.ap, target.bq, origin.ap, origin.bq)] if len(list(abuckets.keys())) != len(list(nabuckets.keys())) or \ len(list(bbuckets.keys())) != len(list(nbbuckets.keys())): raise ValueError('%s not reachable from %s' % (target, origin)) ops = [] def do_shifts(fro, to, inc, dec): ops = [] for i in range(len(fro)): if to[i] - fro[i] > 0: sh = inc ch = 1 else: sh = dec ch = -1 while to[i] != fro[i]: ops += [sh(fro, i)] fro[i] += ch return ops def do_shifts_a(nal, nbk, al, aother, bother): """ Shift us from (nal, nbk) to (al, nbk). """ return do_shifts(nal, al, lambda p, i: ShiftA(p[i]), lambda p, i: UnShiftA(p + aother, nbk + bother, i, z)) def do_shifts_b(nal, nbk, bk, aother, bother): """ Shift us from (nal, nbk) to (nal, bk). """ return do_shifts(nbk, bk, lambda p, i: UnShiftB(nal + aother, p + bother, i, z), lambda p, i: ShiftB(p[i])) for r in sorted(list(abuckets.keys()) + list(bbuckets.keys()), key=default_sort_key): al = () nal = () bk = () nbk = () if r in abuckets: al = abuckets[r] nal = nabuckets[r] if r in bbuckets: bk = bbuckets[r] nbk = nbbuckets[r] if len(al) != len(nal) or len(bk) != len(nbk): raise ValueError('%s not reachable from %s' % (target, origin)) al, nal, bk, nbk = [sorted(list(w), key=default_sort_key) for w in [al, nal, bk, nbk]] def others(dic, key): l = [] for k, value in dic.items(): if k != key: l += list(dic[k]) return l aother = others(nabuckets, r) bother = others(nbbuckets, r) if len(al) == 0: # there can be no complications, just shift the bs as we please ops += do_shifts_b([], nbk, bk, aother, bother) elif len(bk) == 0: # there can be no complications, just shift the as as we please ops += do_shifts_a(nal, [], al, aother, bother) else: namax = nal[-1] amax = al[-1] if nbk[0] - namax <= 0 or bk[0] - amax <= 0: raise ValueError('Non-suitable parameters.') if namax - amax > 0: # we are going to shift down - first do the as, then the bs ops += do_shifts_a(nal, nbk, al, aother, bother) ops += do_shifts_b(al, nbk, bk, aother, bother) else: # we are going to shift up - first do the bs, then the as ops += do_shifts_b(nal, nbk, bk, aother, bother) ops += do_shifts_a(nal, bk, al, aother, bother) nabuckets[r] = al nbbuckets[r] = bk ops.reverse() return ops def try_shifted_sum(func, z): """ Try to recognise a hypergeometric sum that starts from k > 0. """ abuckets, bbuckets = sift(func.ap, _mod1), sift(func.bq, _mod1) if len(abuckets[S(0)]) != 1: return None r = abuckets[S(0)][0] if r <= 0: return None if not S(0) in bbuckets: return None l = list(bbuckets[S(0)]) l.sort() k = l[0] if k <= 0: return None nap = list(func.ap) nap.remove(r) nbq = list(func.bq) nbq.remove(k) k -= 1 nap = [x - k for x in nap] nbq = [x - k for x in nbq] ops = [] for n in range(r - 1): ops.append(ShiftA(n + 1)) ops.reverse() fac = factorial(k)/z*k for a in nap: fac /= rf(a, k) for b in nbq: fac = rf(b, k) ops += [MultOperator(fac)] p = 0 for n in range(k): m = z*n/factorial(n) for a in nap: m = rf(a, n) for b in nbq: m /= rf(b, n) p += m return Hyper_Function(nap, nbq), ops, -p def try_polynomial(func, z): """ Recognise polynomial cases. Returns None if not such a case. Requires order to be fully reduced. """ abuckets, bbuckets = sift(func.ap, _mod1), sift(func.bq, _mod1) a0 = abuckets[S(0)] b0 = bbuckets[S(0)] a0.sort() b0.sort() al0 = [x for x in a0 if x <= 0] bl0 = [x for x in b0 if x <= 0] if bl0 and all(a < bl0[-1] for a in al0): return oo if not al0: return None a = al0[-1] fac = 1 res = S(1) for n in Tuple(list(range(-a))): fac = z fac /= n + 1 for a in func.ap: fac = a + n for b in func.bq: fac /= b + n res += fac return res def try_lerchphi(func): """ Try to find an expression for Hyper_Function ``func`` in terms of Lerch Transcendents. Return None if no such expression can be found. """ # This is actually quite simple, and is described in Roach's paper, # section 18. # We don't need to implement the reduction to polylog here, this # is handled by expand_func. from sympy.matrices import Matrix, zeros from sympy.polys import apart # First we need to figure out if the summation coefficient is a rational # function of the summation index, and construct that rational function. abuckets, bbuckets = sift(func.ap, _mod1), sift(func.bq, _mod1) paired = {} for key, value in abuckets.items(): if key != 0 and not key in bbuckets: return None bvalue = bbuckets[key] paired[key] = (list(value), list(bvalue)) bbuckets.pop(key, None) if bbuckets != {}: return None if not S(0) in abuckets: return None aints, bints = paired[S(0)] # Account for the additional n! in denominator paired[S(0)] = (aints, bints + [1]) t = Dummy('t') numer = S(1) denom = S(1) for key, (avalue, bvalue) in paired.items(): if len(avalue) != len(bvalue): return None # Note that since order has been reduced fully, all the b are # bigger than all the a they differ from by an integer. In particular # if there are any negative b left, this function is not well-defined. for a, b in zip(avalue, bvalue): if (a - b).is_positive: k = a - b numer = rf(b + t, k) denom = rf(b, k) else: k = b - a numer = rf(a, k) denom = rf(a + t, k) # Now do a partial fraction decomposition. # We assemble two structures: a list monomials of pairs (a, b) representing # atb (b a non-negative integer), and a dict terms, where # terms[a] = [(b, c)] means that there is a term b/(t-a)c. part = apart(numer/denom, t) args = Add.make_args(part) monomials = [] terms = {} for arg in args: numer, denom = arg.as_numer_denom() if not denom.has(t): p = Poly(numer, t) if not p.is_monomial: raise TypeError("p should be monomial") ((b, ), a) = p.LT() monomials += [(a/denom, b)] continue if numer.has(t): raise NotImplementedError('Need partial fraction decomposition' ' with linear denominators') indep, [dep] = denom.as_coeff_mul(t) n = 1 if dep.is_Pow: n = dep.exp dep = dep.base if dep == t: a == 0 elif dep.is_Add: a, tmp = dep.as_independent(t) b = 1 if tmp != t: b, _ = tmp.as_independent(t) if dep != bt + a: raise NotImplementedError('unrecognised form %s' % dep) a /= b indep = b*n else: raise NotImplementedError('unrecognised form of partial fraction') terms.setdefault(a, []).append((numer/indep, n)) # Now that we have this information, assemble our formula. All the # monomials yield rational functions and go into one basis element. # The terms[a] are related by differentiation. If the largest exponent is # n, we need lerchphi(z, k, a) for k = 1, 2, ..., n. # deriv maps a basis to its derivative, expressed as a C(z)-linear # combination of other basis elements. deriv = {} coeffs = {} z = Dummy('z') monomials.sort(key=lambda x: x[1]) mon = {0: 1/(1 - z)} if monomials: for k in range(monomials[-1][1]): mon[k + 1] = zmon[k].diff(z) for a, n in monomials: coeffs.setdefault(S(1), []).append(amon[n]) for a, l in terms.items(): for c, k in l: coeffs.setdefault(lerchphi(z, k, a), []).append(c) l.sort(key=lambda x: x[1]) for k in range(2, l[-1][1] + 1): deriv[lerchphi(z, k, a)] = [(-a, lerchphi(z, k, a)), (1, lerchphi(z, k - 1, a))] deriv[lerchphi(z, 1, a)] = [(-a, lerchphi(z, 1, a)), (1/(1 - z), S(1))] trans = {} for n, b in enumerate([S(1)] + list(deriv.keys())): trans[b] = n basis = [expand_func(b) for (b, _) in sorted(list(trans.items()), key=lambda x:x[1])] B = Matrix(basis) C = Matrix([[0]len(B)]) for b, c in coeffs.items(): C[trans[b]] = Add(c) M = zeros(len(B)) for b, l in deriv.items(): for c, b2 in l: M[trans[b], trans[b2]] = c return Formula(func, z, None, [], B, C, M) def build_hypergeometric_formula(func): """ Create a formula object representing the hypergeometric function ``func``. """ # We know that no `ap` are negative integers, otherwise "detect poly" # would have kicked in. However, `ap` could be empty. In this case we can # use a different basis. # I'm not aware of a basis that works in all cases. from sympy import zeros, Matrix, eye z = Dummy('z') if func.ap: afactors = [_x + a for a in func.ap] bfactors = [_x + b - 1 for b in func.bq] expr = _xMul(bfactors) - zMul(afactors) poly = Poly(expr, _x) n = poly.degree() basis = [] M = zeros(n) for k in range(n): a = func.ap[0] + k basis += [hyper([a] + list(func.ap[1:]), func.bq, z)] if k < n - 1: M[k, k] = -a M[k, k + 1] = a B = Matrix(basis) C = Matrix([[1] + [0](n - 1)]) derivs = [eye(n)] for k in range(n): derivs.append(Mderivs[k]) l = poly.all_coeffs() l.reverse() res = [0]n for k, c in enumerate(l): for r, d in enumerate(Cderivs[k]): res[r] += cd for k, c in enumerate(res): M[n - 1, k] = -c/derivs[n - 1][0, n - 1]/poly.all_coeffs()[0] return Formula(func, z, None, [], B, C, M) else: # Since there are no `ap`, none of the `bq` can be non-positive # integers. basis = [] bq = list(func.bq[:]) for i in range(len(bq)): basis += [hyper([], bq, z)] bq[i] += 1 basis += [hyper([], bq, z)] B = Matrix(basis) n = len(B) C = Matrix([[1] + [0](n - 1)]) M = zeros(n) M[0, n - 1] = z/Mul(func.bq) for k in range(1, n): M[k, k - 1] = func.bq[k - 1] M[k, k] = -func.bq[k - 1] return Formula(func, z, None, [], B, C, M) def hyperexpand_special(ap, bq, z): """ Try to find a closed-form expression for hyper(ap, bq, z), where ``z`` is supposed to be a "special" value, e.g. 1. This function tries various of the classical summation formulae (Gauss, Saalschuetz, etc). """ # This code is very ad-hoc. There are many clever algorithms # (notably Zeilberger's) related to this problem. # For now we just want a few simple cases to work. p, q = len(ap), len(bq) z_ = z z = unpolarify(z) if z == 0: return S.One if p == 2 and q == 1: # 2F1 a, b, c = ap + bq if z == 1: # Gauss return gamma(c - a - b)gamma(c)/gamma(c - a)/gamma(c - b) if z == -1 and simplify(b - a + c) == 1: b, a = a, b if z == -1 and simplify(a - b + c) == 1: # Kummer if b.is_integer and b.is_negative: return 2cos(pib/2)gamma(-b)gamma(b - a + 1) \ /gamma(-b/2)/gamma(b/2 - a + 1) else: return gamma(b/2 + 1)gamma(b - a + 1) \ /gamma(b + 1)/gamma(b/2 - a + 1) # TODO tons of more formulae # investigate what algorithms exist return hyper(ap, bq, z_) _collection = None def _hyperexpand(func, z, ops0=[], z0=Dummy('z0'), premult=1, prem=0, rewrite='default'): """ Try to find an expression for the hypergeometric function ``func``. The result is expressed in terms of a dummy variable z0. Then it is multiplied by premult. Then ops0 is applied. premult must be azprem for some a independent of z. """ if z is S.Zero: return S.One z = polarify(z, subs=False) if rewrite == 'default': rewrite = 'nonrepsmall' def carryout_plan(f, ops): C = apply_operators(f.C.subs(f.z, z0), ops, make_derivative_operator(f.M.subs(f.z, z0), z0)) from sympy import eye C = apply_operators(C, ops0, make_derivative_operator(f.M.subs(f.z, z0) + premeye(f.M.shape[0]), z0)) if premult == 1: C = C.applyfunc(make_simp(z0)) r = Cf.B.subs(f.z, z0)premult res = r[0].subs(z0, z) if rewrite: res = res.rewrite(rewrite) return res # TODO # The following would be possible: # ) PFD Duplication (see Kelly Roach's paper) # ) In a similar spirit, try_lerchphi() can be generalised considerably. global _collection if _collection is None: _collection = FormulaCollection() debug('Trying to expand hypergeometric function ', func) # First reduce order as much as possible. func, ops = reduce_order(func) if ops: debug(' Reduced order to ', func) else: debug(' Could not reduce order.') # Now try polynomial cases res = try_polynomial(func, z0) if res is not None: debug(' Recognised polynomial.') p = apply_operators(res, ops, lambda f: z0f.diff(z0)) p = apply_operators(ppremult, ops0, lambda f: z0f.diff(z0)) return unpolarify(simplify(p).subs(z0, z)) # Try to recognise a shifted sum. p = S(0) res = try_shifted_sum(func, z0) if res is not None: func, nops, p = res debug(' Recognised shifted sum, reduced order to ', func) ops += nops # apply the plan for poly p = apply_operators(p, ops, lambda f: z0f.diff(z0)) p = apply_operators(ppremult, ops0, lambda f: z0f.diff(z0)) p = simplify(p).subs(z0, z) # Try special expansions early. if unpolarify(z) in [1, -1] and (len(func.ap), len(func.bq)) == (2, 1): f = build_hypergeometric_formula(func) r = carryout_plan(f, ops).replace(hyper, hyperexpand_special) if not r.has(hyper): return r + p # Try to find a formula in our collection formula = _collection.lookup_origin(func) # Now try a lerch phi formula if formula is None: formula = try_lerchphi(func) if formula is None: debug(' Could not find an origin. ', 'Will return answer in terms of ' 'simpler hypergeometric functions.') formula = build_hypergeometric_formula(func) debug(' Found an origin: ', formula.closed_form, ' ', formula.func) # We need to find the operators that convert formula into func. ops += devise_plan(func, formula.func, z0) # Now carry out the plan. r = carryout_plan(formula, ops) + p return powdenest(r, polar=True).replace(hyper, hyperexpand_special) def devise_plan_meijer(fro, to, z): """ Find operators to convert G-function ``fro`` into G-function ``to``. It is assumed that fro and to have the same signatures, and that in fact any corresponding pair of parameters differs by integers, and a direct path is possible. I.e. if there are parameters a1 b1 c1 and a2 b2 c2 it is assumed that a1 can be shifted to a2, etc. The only thing this routine determines is the order of shifts to apply, nothing clever will be tried. It is also assumed that fro is suitable. Examples ======== >>> from sympy.simplify.hyperexpand import (devise_plan_meijer, ... G_Function) >>> from sympy.abc import z Empty plan: >>> devise_plan_meijer(G_Function([1], [2], [3], [4]), ... G_Function([1], [2], [3], [4]), z) [] Very simple plans: >>> devise_plan_meijer(G_Function([0], [], [], []), ... G_Function([1], [], [], []), z) [<Increment upper a index #0 of [0], [], [], [].>] >>> devise_plan_meijer(G_Function([0], [], [], []), ... G_Function([-1], [], [], []), z) [<Decrement upper a=0.>] >>> devise_plan_meijer(G_Function([], [1], [], []), ... G_Function([], [2], [], []), z) [<Increment lower a index #0 of [], [1], [], [].>] Slightly more complicated plans: >>> devise_plan_meijer(G_Function([0], [], [], []), ... G_Function([2], [], [], []), z) [<Increment upper a index #0 of [1], [], [], [].>, <Increment upper a index #0 of [0], [], [], [].>] >>> devise_plan_meijer(G_Function([0], [], [0], []), ... G_Function([-1], [], [1], []), z) [<Increment upper b=0.>, <Decrement upper a=0.>] Order matters: >>> devise_plan_meijer(G_Function([0], [], [0], []), ... G_Function([1], [], [1], []), z) [<Increment upper a index #0 of [0], [], [1], [].>, <Increment upper b=0.>] """ # TODO for now, we use the following simple heuristic: inverse-shift # when possible, shift otherwise. Give up if we cannot make progress. def try_shift(f, t, shifter, diff, counter): """ Try to apply ``shifter`` in order to bring some element in ``f`` nearer to its counterpart in ``to``. ``diff`` is +/- 1 and determines the effect of ``shifter``. Counter is a list of elements blocking the shift. Return an operator if change was possible, else None. """ for idx, (a, b) in enumerate(zip(f, t)): if ( (a - b).is_integer and (b - a)/diff > 0 and all(a != x for x in counter)): sh = shifter(idx) f[idx] += diff return sh fan = list(fro.an) fap = list(fro.ap) fbm = list(fro.bm) fbq = list(fro.bq) ops = [] change = True while change: change = False op = try_shift(fan, to.an, lambda i: MeijerUnShiftB(fan, fap, fbm, fbq, i, z), 1, fbm + fbq) if op is not None: ops += [op] change = True continue op = try_shift(fap, to.ap, lambda i: MeijerUnShiftD(fan, fap, fbm, fbq, i, z), 1, fbm + fbq) if op is not None: ops += [op] change = True continue op = try_shift(fbm, to.bm, lambda i: MeijerUnShiftA(fan, fap, fbm, fbq, i, z), -1, fan + fap) if op is not None: ops += [op] change = True continue op = try_shift(fbq, to.bq, lambda i: MeijerUnShiftC(fan, fap, fbm, fbq, i, z), -1, fan + fap) if op is not None: ops += [op] change = True continue op = try_shift(fan, to.an, lambda i: MeijerShiftB(fan[i]), -1, []) if op is not None: ops += [op] change = True continue op = try_shift(fap, to.ap, lambda i: MeijerShiftD(fap[i]), -1, []) if op is not None: ops += [op] change = True continue op = try_shift(fbm, to.bm, lambda i: MeijerShiftA(fbm[i]), 1, []) if op is not None: ops += [op] change = True continue op = try_shift(fbq, to.bq, lambda i: MeijerShiftC(fbq[i]), 1, []) if op is not None: ops += [op] change = True continue if fan != list(to.an) or fap != list(to.ap) or fbm != list(to.bm) or \ fbq != list(to.bq): raise NotImplementedError('Could not devise plan.') ops.reverse() return ops _meijercollection = None def _meijergexpand(func, z0, allow_hyper=False, rewrite='default', place=None): """ Try to find an expression for the Meijer G function specified by the G_Function ``func``. If ``allow_hyper`` is True, then returning an expression in terms of hypergeometric functions is allowed. Currently this just does Slater's theorem. If expansions exist both at zero and at infinity, ``place`` can be set to ``0`` or ``zoo`` for the preferred choice. """ global _meijercollection if _meijercollection is None: _meijercollection = MeijerFormulaCollection() if rewrite == 'default': rewrite = None func0 = func debug('Try to expand Meijer G function corresponding to ', func) # We will play games with analytic continuation - rather use a fresh symbol z = Dummy('z') func, ops = reduce_order_meijer(func) if ops: debug(' Reduced order to ', func) else: debug(' Could not reduce order.') # Try to find a direct formula f = _meijercollection.lookup_origin(func) if f is not None: debug(' Found a Meijer G formula: ', f.func) ops += devise_plan_meijer(f.func, func, z) # Now carry out the plan. C = apply_operators(f.C.subs(f.z, z), ops, make_derivative_operator(f.M.subs(f.z, z), z)) C = C.applyfunc(make_simp(z)) r = Cf.B.subs(f.z, z) r = r[0].subs(z, z0) return powdenest(r, polar=True) debug(" Could not find a direct formula. Trying Slater's theorem.") # TODO the following would be possible: # ) Paired Index Theorems # ) PFD Duplication # (See Kelly Roach's paper for details on either.) # # TODO Also, we tend to create combinations of gamma functions that can be # simplified. def can_do(pbm, pap): """ Test if slater applies. """ for i in pbm: if len(pbm[i]) > 1: l = 0 if i in pap: l = len(pap[i]) if l + 1 < len(pbm[i]): return False return True def do_slater(an, bm, ap, bq, z, zfinal): # zfinal is the value that will eventually be substituted for z. # We pass it to _hyperexpand to improve performance. func = G_Function(an, bm, ap, bq) _, pbm, pap, _ = func.compute_buckets() if not can_do(pbm, pap): return S(0), False cond = len(an) + len(ap) < len(bm) + len(bq) if len(an) + len(ap) == len(bm) + len(bq): cond = abs(z) < 1 if cond is False: return S(0), False res = S(0) for m in pbm: if len(pbm[m]) == 1: bh = pbm[m][0] fac = 1 bo = list(bm) bo.remove(bh) for bj in bo: fac = gamma(bj - bh) for aj in an: fac = gamma(1 + bh - aj) for bj in bq: fac /= gamma(1 + bh - bj) for aj in ap: fac /= gamma(aj - bh) nap = [1 + bh - a for a in list(an) + list(ap)] nbq = [1 + bh - b for b in list(bo) + list(bq)] k = polar_lift(S(-1)(len(ap) - len(bm))) harg = kzfinal # NOTE even though k "is" +-1, this has to be t/k instead of # tk ... we are using polar numbers for consistency! premult = (t/k)bh hyp = _hyperexpand(Hyper_Function(nap, nbq), harg, ops, t, premult, bh, rewrite=None) res += fac hyp else: b_ = pbm[m][0] ki = [bi - b_ for bi in pbm[m][1:]] u = len(ki) li = [ai - b_ for ai in pap[m][:u + 1]] bo = list(bm) for b in pbm[m]: bo.remove(b) ao = list(ap) for a in pap[m][:u]: ao.remove(a) lu = li[-1] di = [l - k for (l, k) in zip(li, ki)] # We first work out the integrand: s = Dummy('s') integrand = z*s for b in bm: if not Mod(b, 1) and b.is_Number: b = int(round(b)) integrand = gamma(b - s) for a in an: integrand = gamma(1 - a + s) for b in bq: integrand /= gamma(1 - b + s) for a in ap: integrand /= gamma(a - s) # Now sum the finitely many residues: # XXX This speeds up some cases - is it a good idea? integrand = expand_func(integrand) for r in range(int(round(lu))): resid = residue(integrand, s, b_ + r) resid = apply_operators(resid, ops, lambda f: zf.diff(z)) res -= resid # Now the hypergeometric term. au = b_ + lu k = polar_lift(S(-1)*(len(ao) + len(bo) + 1)) harg = kzfinal premult = (t/k)au nap = [1 + au - a for a in list(an) + list(ap)] + [1] nbq = [1 + au - b for b in list(bm) + list(bq)] hyp = _hyperexpand(Hyper_Function(nap, nbq), harg, ops, t, premult, au, rewrite=None) C = S(-1)(lu)/factorial(lu) for i in range(u): C = S(-1)di[i]/rf(lu - li[i] + 1, di[i]) for a in an: C = gamma(1 - a + au) for b in bo: C = gamma(b - au) for a in ao: C /= gamma(a - au) for b in bq: C /= gamma(1 - b + au) res += Chyp return res, cond t = Dummy('t') slater1, cond1 = do_slater(func.an, func.bm, func.ap, func.bq, z, z0) def tr(l): return [1 - x for x in l] for op in ops: op._poly = Poly(op._poly.subs({z: 1/t, _x: -_x}), _x) slater2, cond2 = do_slater(tr(func.bm), tr(func.an), tr(func.bq), tr(func.ap), t, 1/z0) slater1 = powdenest(slater1.subs(z, z0), polar=True) slater2 = powdenest(slater2.subs(t, 1/z0), polar=True) if not isinstance(cond2, bool): cond2 = cond2.subs(t, 1/z) m = func(z) if m.delta > 0 or \ (m.delta == 0 and len(m.ap) == len(m.bq) and (re(m.nu) < -1) is not False and polar_lift(z0) == polar_lift(1)): # The condition delta > 0 means that the convergence region is # connected. Any expression we find can be continued analytically # to the entire convergence region. # The conditions delta==0, p==q, re(nu) < -1 imply that G is continuous # on the positive reals, so the values at z=1 agree. if cond1 is not False: cond1 = True if cond2 is not False: cond2 = True if cond1 is True: slater1 = slater1.rewrite(rewrite or 'nonrep') else: slater1 = slater1.rewrite(rewrite or 'nonrepsmall') if cond2 is True: slater2 = slater2.rewrite(rewrite or 'nonrep') else: slater2 = slater2.rewrite(rewrite or 'nonrepsmall') if cond1 is not False and cond2 is not False: # If one condition is False, there is no choice. if place == 0: cond2 = False if place == zoo: cond1 = False if not isinstance(cond1, bool): cond1 = cond1.subs(z, z0) if not isinstance(cond2, bool): cond2 = cond2.subs(z, z0) def weight(expr, cond): if cond is True: c0 = 0 elif cond is False: c0 = 1 else: c0 = 2 if expr.has(oo, zoo, -oo, nan): # XXX this actually should not happen, but consider # S('meijerg(((0, -1/2, 0, -1/2, 1/2), ()), ((0,), # (-1/2, -1/2, -1/2, -1)), exp_polar(I*pi))/4') c0 = 3 return (c0, expr.count(hyper), expr.count_ops()) w1 = weight(slater1, cond1) w2 = weight(slater2, cond2) if min(w1, w2) <= (0, 1, oo): if w1 < w2: return slater1 else: return slater2 if max(w1[0], w2[0]) <= 1 and max(w1[1], w2[1]) <= 1: return Piecewise((slater1, cond1), (slater2, cond2), (func0(z0), True)) # We couldn't find an expression without hypergeometric functions. # TODO it would be helpful to give conditions under which the integral # is known to diverge. r = Piecewise((slater1, cond1), (slater2, cond2), (func0(z0), True)) if r.has(hyper) and not allow_hyper: debug(' Could express using hypergeometric functions, ' 'but not allowed.') if not r.has(hyper) or allow_hyper: return r return func0(z0) def hyperexpand(f, allow_hyper=False, rewrite='default', place=None): """ Expand hypergeometric functions. If allow_hyper is True, allow partial simplification (that is a result different from input, but still containing hypergeometric functions). If a G-function has expansions both at zero and at infinity, ``place`` can be set to ``0`` or ``zoo`` to indicate the preferred choice. Examples ======== >>> from sympy.simplify.hyperexpand import hyperexpand >>> from sympy.functions import hyper >>> from sympy.abc import z >>> hyperexpand(hyper([], [], z)) exp(z) Non-hyperegeometric parts of the expression and hypergeometric expressions that are not recognised are left unchanged: >>> hyperexpand(1 + hyper([1, 1, 1], [], z)) hyper((1, 1, 1), (), z) + 1 """ f = sympify(f) def do_replace(ap, bq, z): r = _hyperexpand(Hyper_Function(ap, bq), z, rewrite=rewrite) if r is None: return hyper(ap, bq, z) else: return r def do_meijer(ap, bq, z): r = _meijergexpand(G_Function(ap[0], ap[1], bq[0], bq[1]), z, allow_hyper, rewrite=rewrite, place=place) if not r.has(nan, zoo, oo, -oo): return r return f.replace(hyper, do_replace).replace(meijerg, do_meijer)
2c9caed05a79054370733a32acdcd80c3e22caf51eeb7c4fe64b19db94103f4f	from __future__ import print_function, division from collections import defaultdict from sympy.core import (Basic, S, Add, Mul, Pow, Symbol, sympify, expand_mul, expand_func, Function, Dummy, Expr, factor_terms, expand_power_exp) from sympy.core.compatibility import iterable, ordered, range, as_int from sympy.core.evaluate import global_evaluate from sympy.core.function import expand_log, count_ops, _mexpand, _coeff_isneg, nfloat from sympy.core.numbers import Float, I, pi, Rational, Integer from sympy.core.rules import Transform from sympy.core.sympify import _sympify from sympy.functions import gamma, exp, sqrt, log, exp_polar, piecewise_fold from sympy.functions.combinatorial.factorials import CombinatorialFunction from sympy.functions.elementary.complexes import unpolarify from sympy.functions.elementary.exponential import ExpBase from sympy.functions.elementary.hyperbolic import HyperbolicFunction from sympy.functions.elementary.integers import ceiling from sympy.functions.elementary.trigonometric import TrigonometricFunction from sympy.functions.special.bessel import besselj, besseli, besselk, jn, bessely from sympy.polys import together, cancel, factor from sympy.simplify.combsimp import combsimp from sympy.simplify.cse_opts import sub_pre, sub_post from sympy.simplify.powsimp import powsimp from sympy.simplify.radsimp import radsimp, fraction from sympy.simplify.sqrtdenest import sqrtdenest from sympy.simplify.trigsimp import trigsimp, exptrigsimp from sympy.utilities.iterables import has_variety import mpmath def separatevars(expr, symbols=[], dict=False, force=False): """ Separates variables in an expression, if possible. By default, it separates with respect to all symbols in an expression and collects constant coefficients that are independent of symbols. If dict=True then the separated terms will be returned in a dictionary keyed to their corresponding symbols. By default, all symbols in the expression will appear as keys; if symbols are provided, then all those symbols will be used as keys, and any terms in the expression containing other symbols or non-symbols will be returned keyed to the string 'coeff'. (Passing None for symbols will return the expression in a dictionary keyed to 'coeff'.) If force=True, then bases of powers will be separated regardless of assumptions on the symbols involved. Notes ===== The order of the factors is determined by Mul, so that the separated expressions may not necessarily be grouped together. Although factoring is necessary to separate variables in some expressions, it is not necessary in all cases, so one should not count on the returned factors being factored. Examples ======== >>> from sympy.abc import x, y, z, alpha >>> from sympy import separatevars, sin >>> separatevars((xy)y) (xy)*y >>> separatevars((xy)y, force=True) xyyy >>> e = 2x*2zsin(y)+2zx2 >>> separatevars(e) 2x*2z(sin(y) + 1) >>> separatevars(e, symbols=(x, y), dict=True) {'coeff': 2z, x: x*2, y: sin(y) + 1} >>> separatevars(e, [x, y, alpha], dict=True) {'coeff': 2z, alpha: 1, x: x*2, y: sin(y) + 1} If the expression is not really separable, or is only partially separable, separatevars will do the best it can to separate it by using factoring. >>> separatevars(x + xy - 3x2) -x(3x - y - 1) If the expression is not separable then expr is returned unchanged or (if dict=True) then None is returned. >>> eq = 2x + ysin(x) >>> separatevars(eq) == eq True >>> separatevars(2x + ysin(x), symbols=(x, y), dict=True) == None True """ expr = sympify(expr) if dict: return _separatevars_dict(_separatevars(expr, force), symbols) else: return _separatevars(expr, force) def _separatevars(expr, force): if len(expr.free_symbols) == 1: return expr # don't destroy a Mul since much of the work may already be done if expr.is_Mul: args = list(expr.args) changed = False for i, a in enumerate(args): args[i] = separatevars(a, force) changed = changed or args[i] != a if changed: expr = expr.func(args) return expr # get a Pow ready for expansion if expr.is_Pow: expr = Pow(separatevars(expr.base, force=force), expr.exp) # First try other expansion methods expr = expr.expand(mul=False, multinomial=False, force=force) _expr, reps = posify(expr) if force else (expr, {}) expr = factor(_expr).subs(reps) if not expr.is_Add: return expr # Find any common coefficients to pull out args = list(expr.args) commonc = args[0].args_cnc(cset=True, warn=False)[0] for i in args[1:]: commonc &= i.args_cnc(cset=True, warn=False)[0] commonc = Mul(commonc) commonc = commonc.as_coeff_Mul()[1] # ignore constants commonc_set = commonc.args_cnc(cset=True, warn=False)[0] # remove them for i, a in enumerate(args): c, nc = a.args_cnc(cset=True, warn=False) c = c - commonc_set args[i] = Mul(c)Mul(nc) nonsepar = Add(args) if len(nonsepar.free_symbols) > 1: _expr = nonsepar _expr, reps = posify(_expr) if force else (_expr, {}) _expr = (factor(_expr)).subs(reps) if not _expr.is_Add: nonsepar = _expr return commoncnonsepar def _separatevars_dict(expr, symbols): if symbols: if not all((t.is_Atom for t in symbols)): raise ValueError("symbols must be Atoms.") symbols = list(symbols) elif symbols is None: return {'coeff': expr} else: symbols = list(expr.free_symbols) if not symbols: return None ret = dict(((i, []) for i in symbols + ['coeff'])) for i in Mul.make_args(expr): expsym = i.free_symbols intersection = set(symbols).intersection(expsym) if len(intersection) > 1: return None if len(intersection) == 0: # There are no symbols, so it is part of the coefficient ret['coeff'].append(i) else: ret[intersection.pop()].append(i) # rebuild for k, v in ret.items(): ret[k] = Mul(v) return ret def _is_sum_surds(p): args = p.args if p.is_Add else [p] for y in args: if not ((y2).is_Rational and y.is_real): return False return True def posify(eq): """Return eq (with generic symbols made positive) and a dictionary containing the mapping between the old and new symbols. Any symbol that has positive=None will be replaced with a positive dummy symbol having the same name. This replacement will allow more symbolic processing of expressions, especially those involving powers and logarithms. A dictionary that can be sent to subs to restore eq to its original symbols is also returned. >>> from sympy import posify, Symbol, log, solve >>> from sympy.abc import x >>> posify(x + Symbol('p', positive=True) + Symbol('n', negative=True)) (_x + n + p, {_x: x}) >>> eq = 1/x >>> log(eq).expand() log(1/x) >>> log(posify(eq)[0]).expand() -log(_x) >>> p, rep = posify(eq) >>> log(p).expand().subs(rep) -log(x) It is possible to apply the same transformations to an iterable of expressions: >>> eq = x2 - 4 >>> solve(eq, x) [-2, 2] >>> eq_x, reps = posify([eq, x]); eq_x [_x2 - 4, _x] >>> solve(eq_x) [2] """ eq = sympify(eq) if iterable(eq): f = type(eq) eq = list(eq) syms = set() for e in eq: syms = syms.union(e.atoms(Symbol)) reps = {} for s in syms: reps.update(dict((v, k) for k, v in posify(s)[1].items())) for i, e in enumerate(eq): eq[i] = e.subs(reps) return f(eq), {r: s for s, r in reps.items()} reps = dict([(s, Dummy(s.name, positive=True)) for s in eq.free_symbols if s.is_positive is None]) eq = eq.subs(reps) return eq, {r: s for s, r in reps.items()} def hypersimp(f, k): """Given combinatorial term f(k) simplify its consecutive term ratio i.e. f(k+1)/f(k). The input term can be composed of functions and integer sequences which have equivalent representation in terms of gamma special function. The algorithm performs three basic steps: 1. Rewrite all functions in terms of gamma, if possible. 2. Rewrite all occurrences of gamma in terms of products of gamma and rising factorial with integer, absolute constant exponent. 3. Perform simplification of nested fractions, powers and if the resulting expression is a quotient of polynomials, reduce their total degree. If f(k) is hypergeometric then as result we arrive with a quotient of polynomials of minimal degree. Otherwise None is returned. For more information on the implemented algorithm refer to: 1. W. Koepf, Algorithms for m-fold Hypergeometric Summation, Journal of Symbolic Computation (1995) 20, 399-417 """ f = sympify(f) g = f.subs(k, k + 1) / f g = g.rewrite(gamma) g = expand_func(g) g = powsimp(g, deep=True, combine='exp') if g.is_rational_function(k): return simplify(g, ratio=S.Infinity) else: return None def hypersimilar(f, g, k): """Returns True if 'f' and 'g' are hyper-similar. Similarity in hypergeometric sense means that a quotient of f(k) and g(k) is a rational function in k. This procedure is useful in solving recurrence relations. For more information see hypersimp(). """ f, g = list(map(sympify, (f, g))) h = (f/g).rewrite(gamma) h = h.expand(func=True, basic=False) return h.is_rational_function(k) def signsimp(expr, evaluate=None): """Make all Add sub-expressions canonical wrt sign. If an Add subexpression, ``a``, can have a sign extracted, as determined by could_extract_minus_sign, it is replaced with Mul(-1, a, evaluate=False). This allows signs to be extracted from powers and products. Examples ======== >>> from sympy import signsimp, exp, symbols >>> from sympy.abc import x, y >>> i = symbols('i', odd=True) >>> n = -1 + 1/x >>> n/x/(-n)*2 - 1/n/x (-1 + 1/x)/(x(1 - 1/x)*2) - 1/(x(-1 + 1/x)) >>> signsimp(_) 0 >>> xn + x-n x(-1 + 1/x) + x(1 - 1/x) >>> signsimp(_) 0 Since powers automatically handle leading signs >>> (-2)i -2i signsimp can be used to put the base of a power with an integer exponent into canonical form: >>> ni (-1 + 1/x)i By default, signsimp doesn't leave behind any hollow simplification: if making an Add canonical wrt sign didn't change the expression, the original Add is restored. If this is not desired then the keyword ``evaluate`` can be set to False: >>> e = exp(y - x) >>> signsimp(e) == e True >>> signsimp(e, evaluate=False) exp(-(x - y)) """ if evaluate is None: evaluate = global_evaluate[0] expr = sympify(expr) if not isinstance(expr, Expr) or expr.is_Atom: return expr e = sub_post(sub_pre(expr)) if not isinstance(e, Expr) or e.is_Atom: return e if e.is_Add: return e.func([signsimp(a, evaluate) for a in e.args]) if evaluate: e = e.xreplace({m: -(-m) for m in e.atoms(Mul) if -(-m) != m}) return e def simplify(expr, ratio=1.7, measure=count_ops, rational=False, inverse=False): """Simplifies the given expression. Simplification is not a well defined term and the exact strategies this function tries can change in the future versions of SymPy. If your algorithm relies on "simplification" (whatever it is), try to determine what you need exactly - is it powsimp()?, radsimp()?, together()?, logcombine()?, or something else? And use this particular function directly, because those are well defined and thus your algorithm will be robust. Nonetheless, especially for interactive use, or when you don't know anything about the structure of the expression, simplify() tries to apply intelligent heuristics to make the input expression "simpler". For example: >>> from sympy import simplify, cos, sin >>> from sympy.abc import x, y >>> a = (x + x2)/(xsin(y)*2 + xcos(y)2) >>> a (x2 + x)/(xsin(y)2 + xcos(y)2) >>> simplify(a) x + 1 Note that we could have obtained the same result by using specific simplification functions: >>> from sympy import trigsimp, cancel >>> trigsimp(a) (x2 + x)/x >>> cancel(_) x + 1 In some cases, applying :func:`simplify` may actually result in some more complicated expression. The default ``ratio=1.7`` prevents more extreme cases: if (result length)/(input length) > ratio, then input is returned unmodified. The ``measure`` parameter lets you specify the function used to determine how complex an expression is. The function should take a single argument as an expression and return a number such that if expression ``a`` is more complex than expression ``b``, then ``measure(a) > measure(b)``. The default measure function is :func:`count_ops`, which returns the total number of operations in the expression. For example, if ``ratio=1``, ``simplify`` output can't be longer than input. :: >>> from sympy import sqrt, simplify, count_ops, oo >>> root = 1/(sqrt(2)+3) Since ``simplify(root)`` would result in a slightly longer expression, root is returned unchanged instead:: >>> simplify(root, ratio=1) == root True If ``ratio=oo``, simplify will be applied anyway:: >>> count_ops(simplify(root, ratio=oo)) > count_ops(root) True Note that the shortest expression is not necessary the simplest, so setting ``ratio`` to 1 may not be a good idea. Heuristically, the default value ``ratio=1.7`` seems like a reasonable choice. You can easily define your own measure function based on what you feel should represent the "size" or "complexity" of the input expression. Note that some choices, such as ``lambda expr: len(str(expr))`` may appear to be good metrics, but have other problems (in this case, the measure function may slow down simplify too much for very large expressions). If you don't know what a good metric would be, the default, ``count_ops``, is a good one. For example: >>> from sympy import symbols, log >>> a, b = symbols('a b', positive=True) >>> g = log(a) + log(b) + log(a)log(1/b) >>> h = simplify(g) >>> h log(ab(-log(a) + 1)) >>> count_ops(g) 8 >>> count_ops(h) 5 So you can see that ``h`` is simpler than ``g`` using the count_ops metric. However, we may not like how ``simplify`` (in this case, using ``logcombine``) has created the ``b(log(1/a) + 1)`` term. A simple way to reduce this would be to give more weight to powers as operations in ``count_ops``. We can do this by using the ``visual=True`` option: >>> print(count_ops(g, visual=True)) 2ADD + DIV + 4LOG + MUL >>> print(count_ops(h, visual=True)) 2LOG + MUL + POW + SUB >>> from sympy import Symbol, S >>> def my_measure(expr): ... POW = Symbol('POW') ... # Discourage powers by giving POW a weight of 10 ... count = count_ops(expr, visual=True).subs(POW, 10) ... # Every other operation gets a weight of 1 (the default) ... count = count.replace(Symbol, type(S.One)) ... return count >>> my_measure(g) 8 >>> my_measure(h) 14 >>> 15./8 > 1.7 # 1.7 is the default ratio True >>> simplify(g, measure=my_measure) -log(a)log(b) + log(a) + log(b) Note that because ``simplify()`` internally tries many different simplification strategies and then compares them using the measure function, we get a completely different result that is still different from the input expression by doing this. If rational=True, Floats will be recast as Rationals before simplification. If rational=None, Floats will be recast as Rationals but the result will be recast as Floats. If rational=False(default) then nothing will be done to the Floats. If inverse=True, it will be assumed that a composition of inverse functions, such as sin and asin, can be cancelled in any order. For example, ``asin(sin(x))`` will yield ``x`` without checking whether x belongs to the set where this relation is true. The default is False. """ expr = sympify(expr) try: return expr._eval_simplify(ratio=ratio, measure=measure, rational=rational, inverse=inverse) except AttributeError: pass original_expr = expr = signsimp(expr) from sympy.simplify.hyperexpand import hyperexpand from sympy.functions.special.bessel import BesselBase from sympy import Sum, Product if not isinstance(expr, Basic) or not expr.args: # XXX: temporary hack return expr if inverse and expr.has(Function): expr = inversecombine(expr) if not expr.args: # simplified to atomic return expr if not isinstance(expr, (Add, Mul, Pow, ExpBase)): return expr.func([simplify(x, ratio=ratio, measure=measure, rational=rational, inverse=inverse) for x in expr.args]) if not expr.is_commutative: expr = nc_simplify(expr) # TODO: Apply different strategies, considering expression pattern: # is it a purely rational function? Is there any trigonometric function?... # See also https://github.com/sympy/sympy/pull/185. def shorter(choices): '''Return the choice that has the fewest ops. In case of a tie, the expression listed first is selected.''' if not has_variety(choices): return choices[0] return min(choices, key=measure) # rationalize Floats floats = False if rational is not False and expr.has(Float): floats = True expr = nsimplify(expr, rational=True) expr = bottom_up(expr, lambda w: w.normal()) expr = Mul(powsimp(expr).as_content_primitive()) _e = cancel(expr) expr1 = shorter(_e, _mexpand(_e).cancel()) # issue 6829 expr2 = shorter(together(expr, deep=True), together(expr1, deep=True)) if ratio is S.Infinity: expr = expr2 else: expr = shorter(expr2, expr1, expr) if not isinstance(expr, Basic): # XXX: temporary hack return expr expr = factor_terms(expr, sign=False) # hyperexpand automatically only works on hypergeometric terms expr = hyperexpand(expr) expr = piecewise_fold(expr) if expr.has(BesselBase): expr = besselsimp(expr) if expr.has(TrigonometricFunction, HyperbolicFunction): expr = trigsimp(expr, deep=True) if expr.has(log): expr = shorter(expand_log(expr, deep=True), logcombine(expr)) if expr.has(CombinatorialFunction, gamma): # expression with gamma functions or non-integer arguments is # automatically passed to gammasimp expr = combsimp(expr) if expr.has(Sum): expr = sum_simplify(expr) if expr.has(Product): expr = product_simplify(expr) from sympy.physics.units import Quantity from sympy.physics.units.util import quantity_simplify if expr.has(Quantity): expr = quantity_simplify(expr) short = shorter(powsimp(expr, combine='exp', deep=True), powsimp(expr), expr) short = shorter(short, cancel(short)) short = shorter(short, factor_terms(short), expand_power_exp(expand_mul(short))) if short.has(TrigonometricFunction, HyperbolicFunction, ExpBase): short = exptrigsimp(short) # get rid of hollow 2-arg Mul factorization hollow_mul = Transform( lambda x: Mul(x.args), lambda x: x.is_Mul and len(x.args) == 2 and x.args[0].is_Number and x.args[1].is_Add and x.is_commutative) expr = short.xreplace(hollow_mul) numer, denom = expr.as_numer_denom() if denom.is_Add: n, d = fraction(radsimp(1/denom, symbolic=False, max_terms=1)) if n is not S.One: expr = (numern).expand()/d if expr.could_extract_minus_sign(): n, d = fraction(expr) if d != 0: expr = signsimp(-n/(-d)) if measure(expr) > ratiomeasure(original_expr): expr = original_expr # restore floats if floats and rational is None: expr = nfloat(expr, exponent=False) return expr def sum_simplify(s): """Main function for Sum simplification""" from sympy.concrete.summations import Sum from sympy.core.function import expand terms = Add.make_args(expand(s)) s_t = [] # Sum Terms o_t = [] # Other Terms for term in terms: if isinstance(term, Mul): other = 1 sum_terms = [] if not term.has(Sum): o_t.append(term) continue mul_terms = Mul.make_args(term) for mul_term in mul_terms: if isinstance(mul_term, Sum): r = mul_term._eval_simplify() sum_terms.extend(Add.make_args(r)) else: other = other * mul_term if len(sum_terms): #some simplification may have happened #use if so s_t.append(Mul(sum_terms) other) else: o_t.append(other) elif isinstance(term, Sum): #as above, we need to turn this into an add list r = term._eval_simplify() s_t.extend(Add.make_args(r)) else: o_t.append(term) result = Add(sum_combine(s_t), o_t) return result def sum_combine(s_t): """Helper function for Sum simplification Attempts to simplify a list of sums, by combining limits / sum function's returns the simplified sum """ from sympy.concrete.summations import Sum used = [False] len(s_t) for method in range(2): for i, s_term1 in enumerate(s_t): if not used[i]: for j, s_term2 in enumerate(s_t): if not used[j] and i != j: temp = sum_add(s_term1, s_term2, method) if isinstance(temp, Sum) or isinstance(temp, Mul): s_t[i] = temp s_term1 = s_t[i] used[j] = True result = S.Zero for i, s_term in enumerate(s_t): if not used[i]: result = Add(result, s_term) return result def factor_sum(self, limits=None, radical=False, clear=False, fraction=False, sign=True): """Helper function for Sum simplification if limits is specified, "self" is the inner part of a sum Returns the sum with constant factors brought outside """ from sympy.core.exprtools import factor_terms from sympy.concrete.summations import Sum result = self.function if limits is None else self limits = self.limits if limits is None else limits #avoid any confusion w/ as_independent if result == 0: return S.Zero #get the summation variables sum_vars = set([limit.args[0] for limit in limits]) #finally we try to factor out any common terms #and remove the from the sum if independent retv = factor_terms(result, radical=radical, clear=clear, fraction=fraction, sign=sign) #avoid doing anything bad if not result.is_commutative: return Sum(result, limits) i, d = retv.as_independent(sum_vars) if isinstance(retv, Add): return i * Sum(1, limits) + Sum(d, limits) else: return i * Sum(d, limits) def sum_add(self, other, method=0): """Helper function for Sum simplification""" from sympy.concrete.summations import Sum from sympy import Mul #we know this is something in terms of a constant a sum #so we temporarily put the constants inside for simplification #then simplify the result def __refactor(val): args = Mul.make_args(val) sumv = next(x for x in args if isinstance(x, Sum)) constant = Mul([x for x in args if x != sumv]) return Sum(constant sumv.function, sumv.limits) if isinstance(self, Mul): rself = __refactor(self) else: rself = self if isinstance(other, Mul): rother = __refactor(other) else: rother = other if type(rself) == type(rother): if method == 0: if rself.limits == rother.limits: return factor_sum(Sum(rself.function + rother.function, rself.limits)) elif method == 1: if simplify(rself.function - rother.function) == 0: if len(rself.limits) == len(rother.limits) == 1: i = rself.limits[0][0] x1 = rself.limits[0][1] y1 = rself.limits[0][2] j = rother.limits[0][0] x2 = rother.limits[0][1] y2 = rother.limits[0][2] if i == j: if x2 == y1 + 1: return factor_sum(Sum(rself.function, (i, x1, y2))) elif x1 == y2 + 1: return factor_sum(Sum(rself.function, (i, x2, y1))) return Add(self, other) def product_simplify(s): """Main function for Product simplification""" from sympy.concrete.products import Product terms = Mul.make_args(s) p_t = [] # Product Terms o_t = [] # Other Terms for term in terms: if isinstance(term, Product): p_t.append(term) else: o_t.append(term) used = [False] * len(p_t) for method in range(2): for i, p_term1 in enumerate(p_t): if not used[i]: for j, p_term2 in enumerate(p_t): if not used[j] and i != j: if isinstance(product_mul(p_term1, p_term2, method), Product): p_t[i] = product_mul(p_term1, p_term2, method) used[j] = True result = Mul(o_t) for i, p_term in enumerate(p_t): if not used[i]: result = Mul(result, p_term) return result def product_mul(self, other, method=0): """Helper function for Product simplification""" from sympy.concrete.products import Product if type(self) == type(other): if method == 0: if self.limits == other.limits: return Product(self.function other.function, self.limits) elif method == 1: if simplify(self.function - other.function) == 0: if len(self.limits) == len(other.limits) == 1: i = self.limits[0][0] x1 = self.limits[0][1] y1 = self.limits[0][2] j = other.limits[0][0] x2 = other.limits[0][1] y2 = other.limits[0][2] if i == j: if x2 == y1 + 1: return Product(self.function, (i, x1, y2)) elif x1 == y2 + 1: return Product(self.function, (i, x2, y1)) return Mul(self, other) def _nthroot_solve(p, n, prec): """ helper function for ``nthroot`` It denests ``pRational(1, n)`` using its minimal polynomial """ from sympy.polys.numberfields import _minimal_polynomial_sq from sympy.solvers import solve while n % 2 == 0: p = sqrtdenest(sqrt(p)) n = n // 2 if n == 1: return p pn = pRational(1, n) x = Symbol('x') f = _minimal_polynomial_sq(p, n, x) if f is None: return None sols = solve(f, x) for sol in sols: if abs(sol - pn).n() < 1./10prec: sol = sqrtdenest(sol) if _mexpand(soln) == p: return sol def logcombine(expr, force=False): """ Takes logarithms and combines them using the following rules: - log(x) + log(y) == log(xy) if both are not negative - alog(x) == log(xa) if x is positive and a is real If ``force`` is True then the assumptions above will be assumed to hold if there is no assumption already in place on a quantity. For example, if ``a`` is imaginary or the argument negative, force will not perform a combination but if ``a`` is a symbol with no assumptions the change will take place. Examples ======== >>> from sympy import Symbol, symbols, log, logcombine, I >>> from sympy.abc import a, x, y, z >>> logcombine(alog(x) + log(y) - log(z)) alog(x) + log(y) - log(z) >>> logcombine(alog(x) + log(y) - log(z), force=True) log(x*ay/z) >>> x,y,z = symbols('x,y,z', positive=True) >>> a = Symbol('a', real=True) >>> logcombine(alog(x) + log(y) - log(z)) log(xay/z) The transformation is limited to factors and/or terms that contain logs, so the result depends on the initial state of expansion: >>> eq = (2 + 3I)log(x) >>> logcombine(eq, force=True) == eq True >>> logcombine(eq.expand(), force=True) log(x*2) + Ilog(x*3) See Also ======== posify: replace all symbols with symbols having positive assumptions sympy.core.function.expand_log: expand the logarithms of products and powers; the opposite of logcombine """ def f(rv): if not (rv.is_Add or rv.is_Mul): return rv def gooda(a): # bool to tell whether the leading ``a`` in ``alog(x)`` # could appear as log(x*a) return (a is not S.NegativeOne and # -1 could* go, but we disallow (a.is_real or force and a.is_real is not False)) def goodlog(l): # bool to tell whether log ``l``'s argument can combine with others a = l.args[0] return a.is_positive or force and a.is_nonpositive is not False other = [] logs = [] log1 = defaultdict(list) for a in Add.make_args(rv): if isinstance(a, log) and goodlog(a): log1[()].append(([], a)) elif not a.is_Mul: other.append(a) else: ot = [] co = [] lo = [] for ai in a.args: if ai.is_Rational and ai < 0: ot.append(S.NegativeOne) co.append(-ai) elif isinstance(ai, log) and goodlog(ai): lo.append(ai) elif gooda(ai): co.append(ai) else: ot.append(ai) if len(lo) > 1: logs.append((ot, co, lo)) elif lo: log1[tuple(ot)].append((co, lo[0])) else: other.append(a) # if there is only one log at each coefficient and none have # an exponent to place inside the log then there is nothing to do if not logs and all(len(log1[k]) == 1 and log1[k][0] == [] for k in log1): return rv # collapse multi-logs as far as possible in a canonical way # TODO: see if xlog(a)+xlog(a)log(b) -> xlog(a)(1+log(b))? # -- in this case, it's unambiguous, but if it were were a log(c) in # each term then it's arbitrary whether they are grouped by log(a) or # by log(c). So for now, just leave this alone; it's probably better to # let the user decide for o, e, l in logs: l = list(ordered(l)) e = log(l.pop(0).args[0]Mul(e)) while l: li = l.pop(0) e = log(li.args[0]*e) c, l = Mul(o), e if isinstance(l, log): # it should be, but check to be sure log1[(c,)].append(([], l)) else: other.append(cl) # logs that have the same coefficient can multiply for k in list(log1.keys()): log1[Mul(k)] = log(logcombine(Mul([ l.args[0]Mul(c) for c, l in log1.pop(k)]), force=force), evaluate=False) # logs that have oppositely signed coefficients can divide for k in ordered(list(log1.keys())): if not k in log1: # already popped as -k continue if -k in log1: # figure out which has the minus sign; the one with # more op counts should be the one num, den = k, -k if num.count_ops() > den.count_ops(): num, den = den, num other.append( numlog(log1.pop(num).args[0]/log1.pop(den).args[0], evaluate=False)) else: other.append(klog1.pop(k)) return Add(other) return bottom_up(expr, f) def inversecombine(expr): """Simplify the composition of a function and its inverse. No attention is paid to whether the inverse is a left inverse or a right inverse; thus, the result will in general not be equivalent to the original expression. Examples ======== >>> from sympy.simplify.simplify import inversecombine >>> from sympy import asin, sin, log, exp >>> from sympy.abc import x >>> inversecombine(asin(sin(x))) x >>> inversecombine(2log(exp(3x))) 6x """ def f(rv): if rv.is_Function and hasattr(rv, "inverse"): if (len(rv.args) == 1 and len(rv.args[0].args) == 1 and isinstance(rv.args[0], rv.inverse(argindex=1))): rv = rv.args[0].args[0] return rv return bottom_up(expr, f) def walk(e, target): """iterate through the args that are the given types (target) and return a list of the args that were traversed; arguments that are not of the specified types are not traversed. Examples ======== >>> from sympy.simplify.simplify import walk >>> from sympy import Min, Max >>> from sympy.abc import x, y, z >>> list(walk(Min(x, Max(y, Min(1, z))), Min)) [Min(x, Max(y, Min(1, z)))] >>> list(walk(Min(x, Max(y, Min(1, z))), Min, Max)) [Min(x, Max(y, Min(1, z))), Max(y, Min(1, z)), Min(1, z)] See Also ======== bottom_up """ if isinstance(e, target): yield e for i in e.args: for w in walk(i, target): yield w def bottom_up(rv, F, atoms=False, nonbasic=False): """Apply ``F`` to all expressions in an expression tree from the bottom up. If ``atoms`` is True, apply ``F`` even if there are no args; if ``nonbasic`` is True, try to apply ``F`` to non-Basic objects. """ try: if rv.args: args = tuple([bottom_up(a, F, atoms, nonbasic) for a in rv.args]) if args != rv.args: rv = rv.func(args) rv = F(rv) elif atoms: rv = F(rv) except AttributeError: if nonbasic: try: rv = F(rv) except TypeError: pass return rv def besselsimp(expr): """ Simplify bessel-type functions. This routine tries to simplify bessel-type functions. Currently it only works on the Bessel J and I functions, however. It works by looking at all such functions in turn, and eliminating factors of "I" and "-1" (actually their polar equivalents) in front of the argument. Then, functions of half-integer order are rewritten using strigonometric functions and functions of integer order (> 1) are rewritten using functions of low order. Finally, if the expression was changed, compute factorization of the result with factor(). >>> from sympy import besselj, besseli, besselsimp, polar_lift, I, S >>> from sympy.abc import z, nu >>> besselsimp(besselj(nu, zpolar_lift(-1))) exp(Ipinu)besselj(nu, z) >>> besselsimp(besseli(nu, zpolar_lift(-I))) exp(-Ipinu/2)besselj(nu, z) >>> besselsimp(besseli(S(-1)/2, z)) sqrt(2)cosh(z)/(sqrt(pi)sqrt(z)) >>> besselsimp(zbesseli(0, z) + z(besseli(2, z))/2 + besseli(1, z)) 3zbesseli(0, z)/2 """ # TODO # - better algorithm? # - simplify (cos(pib)besselj(b,z) - besselj(-b,z))/sin(pib) ... # - use contiguity relations? def replacer(fro, to, factors): factors = set(factors) def repl(nu, z): if factors.intersection(Mul.make_args(z)): return to(nu, z) return fro(nu, z) return repl def torewrite(fro, to): def tofunc(nu, z): return fro(nu, z).rewrite(to) return tofunc def tominus(fro): def tofunc(nu, z): return exp(Ipinu)fro(nu, exp_polar(-Ipi)z) return tofunc orig_expr = expr ifactors = [I, exp_polar(Ipi/2), exp_polar(-Ipi/2)] expr = expr.replace( besselj, replacer(besselj, torewrite(besselj, besseli), ifactors)) expr = expr.replace( besseli, replacer(besseli, torewrite(besseli, besselj), ifactors)) minusfactors = [-1, exp_polar(Ipi)] expr = expr.replace( besselj, replacer(besselj, tominus(besselj), minusfactors)) expr = expr.replace( besseli, replacer(besseli, tominus(besseli), minusfactors)) z0 = Dummy('z') def expander(fro): def repl(nu, z): if (nu % 1) == S(1)/2: return simplify(trigsimp(unpolarify( fro(nu, z0).rewrite(besselj).rewrite(jn).expand( func=True)).subs(z0, z))) elif nu.is_Integer and nu > 1: return fro(nu, z).expand(func=True) return fro(nu, z) return repl expr = expr.replace(besselj, expander(besselj)) expr = expr.replace(bessely, expander(bessely)) expr = expr.replace(besseli, expander(besseli)) expr = expr.replace(besselk, expander(besselk)) if expr != orig_expr: expr = expr.factor() return expr def nthroot(expr, n, max_len=4, prec=15): """ compute a real nth-root of a sum of surds Parameters ========== expr : sum of surds n : integer max_len : maximum number of surds passed as constants to ``nsimplify`` Algorithm ========= First ``nsimplify`` is used to get a candidate root; if it is not a root the minimal polynomial is computed; the answer is one of its roots. Examples ======== >>> from sympy.simplify.simplify import nthroot >>> from sympy import Rational, sqrt >>> nthroot(90 + 34sqrt(7), 3) sqrt(7) + 3 """ expr = sympify(expr) n = sympify(n) p = exprRational(1, n) if not n.is_integer: return p if not _is_sum_surds(expr): return p surds = [] coeff_muls = [x.as_coeff_Mul() for x in expr.args] for x, y in coeff_muls: if not x.is_rational: return p if y is S.One: continue if not (y.is_Pow and y.exp == S.Half and y.base.is_integer): return p surds.append(y) surds.sort() surds = surds[:max_len] if expr < 0 and n % 2 == 1: p = (-expr)Rational(1, n) a = nsimplify(p, constants=surds) res = a if _mexpand(an) == _mexpand(-expr) else p return -res a = nsimplify(p, constants=surds) if _mexpand(a) is not _mexpand(p) and _mexpand(an) == _mexpand(expr): return _mexpand(a) expr = _nthroot_solve(expr, n, prec) if expr is None: return p return expr def nsimplify(expr, constants=(), tolerance=None, full=False, rational=None, rational_conversion='base10'): """ Find a simple representation for a number or, if there are free symbols or if rational=True, then replace Floats with their Rational equivalents. If no change is made and rational is not False then Floats will at least be converted to Rationals. For numerical expressions, a simple formula that numerically matches the given numerical expression is sought (and the input should be possible to evalf to a precision of at least 30 digits). Optionally, a list of (rationally independent) constants to include in the formula may be given. A lower tolerance may be set to find less exact matches. If no tolerance is given then the least precise value will set the tolerance (e.g. Floats default to 15 digits of precision, so would be tolerance=10-15). With full=True, a more extensive search is performed (this is useful to find simpler numbers when the tolerance is set low). When converting to rational, if rational_conversion='base10' (the default), then convert floats to rationals using their base-10 (string) representation. When rational_conversion='exact' it uses the exact, base-2 representation. Examples ======== >>> from sympy import nsimplify, sqrt, GoldenRatio, exp, I, exp, pi >>> nsimplify(4/(1+sqrt(5)), [GoldenRatio]) -2 + 2GoldenRatio >>> nsimplify((1/(exp(3piI/5)+1))) 1/2 - Isqrt(sqrt(5)/10 + 1/4) >>> nsimplify(II, [pi]) exp(-pi/2) >>> nsimplify(pi, tolerance=0.01) 22/7 >>> nsimplify(0.333333333333333, rational=True, rational_conversion='exact') 6004799503160655/18014398509481984 >>> nsimplify(0.333333333333333, rational=True) 1/3 See Also ======== sympy.core.function.nfloat """ try: return sympify(as_int(expr)) except (TypeError, ValueError): pass expr = sympify(expr).xreplace({ Float('inf'): S.Infinity, Float('-inf'): S.NegativeInfinity, }) if expr is S.Infinity or expr is S.NegativeInfinity: return expr if rational or expr.free_symbols: return _real_to_rational(expr, tolerance, rational_conversion) # SymPy's default tolerance for Rationals is 15; other numbers may have # lower tolerances set, so use them to pick the largest tolerance if None # was given if tolerance is None: tolerance = 10-min([15] + [mpmath.libmp.libmpf.prec_to_dps(n._prec) for n in expr.atoms(Float)]) # XXX should prec be set independent of tolerance or should it be computed # from tolerance? prec = 30 bprec = int(prec3.33) constants_dict = {} for constant in constants: constant = sympify(constant) v = constant.evalf(prec) if not v.is_Float: raise ValueError("constants must be real-valued") constants_dict[str(constant)] = v._to_mpmath(bprec) exprval = expr.evalf(prec, chop=True) re, im = exprval.as_real_imag() # safety check to make sure that this evaluated to a number if not (re.is_Number and im.is_Number): return expr def nsimplify_real(x): orig = mpmath.mp.dps xv = x._to_mpmath(bprec) try: # We'll be happy with low precision if a simple fraction if not (tolerance or full): mpmath.mp.dps = 15 rat = mpmath.pslq([xv, 1]) if rat is not None: return Rational(-int(rat[1]), int(rat[0])) mpmath.mp.dps = prec newexpr = mpmath.identify(xv, constants=constants_dict, tol=tolerance, full=full) if not newexpr: raise ValueError if full: newexpr = newexpr[0] expr = sympify(newexpr) if x and not expr: # don't let x become 0 raise ValueError if expr.is_finite is False and not xv in [mpmath.inf, mpmath.ninf]: raise ValueError return expr finally: # even though there are returns above, this is executed # before leaving mpmath.mp.dps = orig try: if re: re = nsimplify_real(re) if im: im = nsimplify_real(im) except ValueError: if rational is None: return _real_to_rational(expr, rational_conversion=rational_conversion) return expr rv = re + imS.ImaginaryUnit # if there was a change or rational is explicitly not wanted # return the value, else return the Rational representation if rv != expr or rational is False: return rv return _real_to_rational(expr, rational_conversion=rational_conversion) def _real_to_rational(expr, tolerance=None, rational_conversion='base10'): """ Replace all reals in expr with rationals. Examples ======== >>> from sympy import Rational >>> from sympy.simplify.simplify import _real_to_rational >>> from sympy.abc import x >>> _real_to_rational(.76 + .1x*.5) sqrt(x)/10 + 19/25 If rational_conversion='base10', this uses the base-10 string. If rational_conversion='exact', the exact, base-2 representation is used. >>> _real_to_rational(0.333333333333333, rational_conversion='exact') 6004799503160655/18014398509481984 >>> _real_to_rational(0.333333333333333) 1/3 """ expr = _sympify(expr) inf = Float('inf') p = expr reps = {} reduce_num = None if tolerance is not None and tolerance < 1: reduce_num = ceiling(1/tolerance) for fl in p.atoms(Float): key = fl if reduce_num is not None: r = Rational(fl).limit_denominator(reduce_num) elif (tolerance is not None and tolerance >= 1 and fl.is_Integer is False): r = Rational(toleranceround(fl/tolerance) ).limit_denominator(int(tolerance)) else: if rational_conversion == 'exact': r = Rational(fl) reps[key] = r continue elif rational_conversion != 'base10': raise ValueError("rational_conversion must be 'base10' or 'exact'") r = nsimplify(fl, rational=False) # e.g. log(3).n() -> log(3) instead of a Rational if fl and not r: r = Rational(fl) elif not r.is_Rational: if fl == inf or fl == -inf: r = S.ComplexInfinity elif fl < 0: fl = -fl d = Pow(10, int((mpmath.log(fl)/mpmath.log(10)))) r = -Rational(str(fl/d))d elif fl > 0: d = Pow(10, int((mpmath.log(fl)/mpmath.log(10)))) r = Rational(str(fl/d))d else: r = Integer(0) reps[key] = r return p.subs(reps, simultaneous=True) def clear_coefficients(expr, rhs=S.Zero): """Return `p, r` where `p` is the expression obtained when Rational additive and multiplicative coefficients of `expr` have been stripped away in a naive fashion (i.e. without simplification). The operations needed to remove the coefficients will be applied to `rhs` and returned as `r`. Examples ======== >>> from sympy.simplify.simplify import clear_coefficients >>> from sympy.abc import x, y >>> from sympy import Dummy >>> expr = 4y(6x + 3) >>> clear_coefficients(expr - 2) (y(2x + 1), 1/6) When solving 2 or more expressions like `expr = a`, `expr = b`, etc..., it is advantageous to provide a Dummy symbol for `rhs` and simply replace it with `a`, `b`, etc... in `r`. >>> rhs = Dummy('rhs') >>> clear_coefficients(expr, rhs) (y(2x + 1), _rhs/12) >>> _[1].subs(rhs, 2) 1/6 """ was = None free = expr.free_symbols if expr.is_Rational: return (S.Zero, rhs - expr) while expr and was != expr: was = expr m, expr = ( expr.as_content_primitive() if free else factor_terms(expr).as_coeff_Mul(rational=True)) rhs /= m c, expr = expr.as_coeff_Add(rational=True) rhs -= c expr = signsimp(expr, evaluate = False) if _coeff_isneg(expr): expr = -expr rhs = -rhs return expr, rhs def nc_simplify(expr, deep=True): ''' Simplify a non-commutative expression composed of multiplication and raising to a power by grouping repeated subterms into one power. Priority is given to simplifications that give the fewest number of arguments in the end (for example, in ababcabc simplifying to (ab)2cabc gives 5 arguments while ab(abc)2 has 3). If `expr` is a sum of such terms, the sum of the simplified terms is returned. Keyword argument `deep` controls whether or not subexpressions nested deeper inside the main expression are simplified. See examples below. Setting `deep` to `False` can save time on nested expressions that don't need simplifying on all levels. Examples ======== >>> from sympy import symbols >>> from sympy.simplify.simplify import nc_simplify >>> a, b, c = symbols("a b c", commutative=False) >>> nc_simplify(ababcabc) ab(abc)2 >>> expr = a2ba*4ba4 >>> nc_simplify(expr) a2(ba4)2 >>> nc_simplify(ababc2(ab)2c*2) ((ab)*2c2)2 >>> nc_simplify(abab + 2aca*2ca2ca) (ab)*2 + 2(aca)3 >>> nc_simplify(b-1a-1(ab)2) ab >>> nc_simplify(a*-1b*-1ca) (ba)*(-1)ca >>> expr = (abab)*2acac >>> nc_simplify(expr) (ab)*4(ac)2 >>> nc_simplify(expr, deep=False) (abab)*2(ac)2 ''' from sympy.matrices.expressions import (MatrixExpr, MatAdd, MatMul, MatPow, MatrixSymbol) from sympy.core.exprtools import factor_nc if isinstance(expr, MatrixExpr): expr = expr.doit(inv_expand=False) _Add, _Mul, _Pow, _Symbol = MatAdd, MatMul, MatPow, MatrixSymbol else: _Add, _Mul, _Pow, _Symbol = Add, Mul, Pow, Symbol # =========== Auxiliary functions ======================== def _overlaps(args): # Calculate a list of lists m such that m[i][j] contains the lengths # of all possible overlaps between args[:i+1] and args[i+1+j:]. # An overlap is a suffix of the prefix that matches a prefix # of the suffix. # For example, let expr=cabababab. Then m[3][0] contains # the lengths of overlaps of cabab with abab. The overlaps # are abab, ab and the empty word so that m[3][0]=[4,2,0]. # All overlaps rather than only the longest one are recorded # because this information helps calculate other overlap lengths. m = [[([1, 0] if a == args[0] else [0]) for a in args[1:]]] for i in range(1, len(args)): overlaps = [] j = 0 for j in range(len(args) - i - 1): overlap = [] for v in m[i-1][j+1]: if j + i + 1 + v < len(args) and args[i] == args[j+i+1+v]: overlap.append(v + 1) overlap += [0] overlaps.append(overlap) m.append(overlaps) return m def _reduce_inverses(_args): # replace consecutive negative powers by an inverse # of a product of positive powers, e.g. a*-1b*-1c # will simplify to (ab)-1c; # return that new args list and the number of negative # powers in it (inv_tot) inv_tot = 0 # total number of inverses inverses = [] args = [] for arg in _args: if isinstance(arg, _Pow) and arg.args[1] < 0: inverses = [arg-1] + inverses inv_tot += 1 else: if len(inverses) == 1: args.append(inverses[0]-1) elif len(inverses) > 1: args.append(_Pow(_Mul(inverses), -1)) inv_tot -= len(inverses) - 1 inverses = [] args.append(arg) if inverses: args.append(_Pow(_Mul(inverses), -1)) inv_tot -= len(inverses) - 1 return inv_tot, tuple(args) def get_score(s): # compute the number of arguments of s # (including in nested expressions) overall # but ignore exponents if isinstance(s, _Pow): return get_score(s.args[0]) elif isinstance(s, (_Add, _Mul)): return sum([get_score(a) for a in s.args]) return 1 def compare(s, alt_s): # compare two possible simplifications and return a # "better" one if s != alt_s and get_score(alt_s) < get_score(s): return alt_s return s # ======================================================== if not isinstance(expr, (_Add, _Mul, _Pow)) or expr.is_commutative: return expr args = expr.args[:] if isinstance(expr, _Pow): if deep: return _Pow(nc_simplify(args[0]), args[1]).doit() else: return expr elif isinstance(expr, _Add): return _Add([nc_simplify(a, deep=deep) for a in args]).doit() else: # get the non-commutative part c_args, args = expr.args_cnc() com_coeff = Mul(c_args) if com_coeff != 1: return com_coeffnc_simplify(expr/com_coeff, deep=deep) inv_tot, args = _reduce_inverses(args) # if most arguments are negative, work with the inverse # of the expression, e.g. a-1ba-1c*-1 will become # (cab-1a)*-1 at the end so can work with cab-1a invert = False if inv_tot > len(args)/2: invert = True args = [a*-1 for a in args[::-1]] if deep: args = tuple(nc_simplify(a) for a in args) m = _overlaps(args) # simps will be {subterm: end} where `end` is the ending # index of a sequence of repetitions of subterm; # this is for not wasting time with subterms that are part # of longer, already considered sequences simps = {} post = 1 pre = 1 # the simplification coefficient is the number of # arguments by which contracting a given sequence # would reduce the word; e.g. in ababcabc, # contracting abab to (ab)*2 removes 3 arguments # while abcabc to (abc)*2 removes 6. It's # better to contract the latter so simplification # with a maximum simplification coefficient will be chosen max_simp_coeff = 0 simp = None # information about future simplification for i in range(1, len(args)): simp_coeff = 0 l = 0 # length of a subterm p = 0 # the power of a subterm if i < len(args) - 1: rep = m[i][0] start = i # starting index of the repeated sequence end = i+1 # ending index of the repeated sequence if i == len(args)-1 or rep == [0]: # no subterm is repeated at this stage, at least as # far as the arguments are concerned - there may be # a repetition if powers are taken into account if (isinstance(args[i], _Pow) and not isinstance(args[i].args[0], _Symbol)): subterm = args[i].args[0].args l = len(subterm) if args[i-l:i] == subterm: # e.g. ab in ab(ab)2 is not repeated # in args (= [a, b, (ab)*2]) but it # can be matched here p += 1 start -= l if args[i+1:i+1+l] == subterm: # e.g. ab in (ab)2ab p += 1 end += l if p: p += args[i].args[1] else: continue else: l = rep[0] # length of the longest repeated subterm at this point start -= l - 1 subterm = args[start:end] p = 2 end += l if subterm in simps and simps[subterm] >= start: # the subterm is part of a sequence that # has already been considered continue # count how many times it's repeated while end < len(args): if l in m[end-1][0]: p += 1 end += l elif isinstance(args[end], _Pow) and args[end].args[0].args == subterm: # for cases like abab(ab)*2ab p += args[end].args[1] end += 1 else: break # see if another match can be made, e.g. # for ba*2 in ba*2ba3 or ab in # a*2bab pre_exp = 0 pre_arg = 1 if start - l >= 0 and args[start-l+1:start] == subterm[1:]: if isinstance(subterm[0], _Pow): pre_arg = subterm[0].args[0] exp = subterm[0].args[1] else: pre_arg = subterm[0] exp = 1 if isinstance(args[start-l], _Pow) and args[start-l].args[0] == pre_arg: pre_exp = args[start-l].args[1] - exp start -= l p += 1 elif args[start-l] == pre_arg: pre_exp = 1 - exp start -= l p += 1 post_exp = 0 post_arg = 1 if end + l - 1 < len(args) and args[end:end+l-1] == subterm[:-1]: if isinstance(subterm[-1], _Pow): post_arg = subterm[-1].args[0] exp = subterm[-1].args[1] else: post_arg = subterm[-1] exp = 1 if isinstance(args[end+l-1], _Pow) and args[end+l-1].args[0] == post_arg: post_exp = args[end+l-1].args[1] - exp end += l p += 1 elif args[end+l-1] == post_arg: post_exp = 1 - exp end += l p += 1 # Consider aba*2ba2ba: # ba*2 is explicitly repeated, but note # that in this case aba is also repeated # so there are two possible simplifications: # a(ba2)3a*-1 or (aba)3 # The latter is obviously simpler. # But in aba2b*2a*2 the simplifications are # a(ba2)2 and (aba)3a in which case # it's better to stick with the shorter subterm if post_exp and exp % 2 == 0 and start > 0: exp = exp/2 _pre_exp = 1 _post_exp = 1 if isinstance(args[start-1], _Pow) and args[start-1].args[0] == post_arg: _post_exp = post_exp + exp _pre_exp = args[start-1].args[1] - exp elif args[start-1] == post_arg: _post_exp = post_exp + exp _pre_exp = 1 - exp if _pre_exp == 0 or _post_exp == 0: if not pre_exp: start -= 1 post_exp = _post_exp pre_exp = _pre_exp pre_arg = post_arg subterm = (post_argexp,) + subterm[:-1] + (post_argexp,) simp_coeff += end-start if post_exp: simp_coeff -= 1 if pre_exp: simp_coeff -= 1 simps[subterm] = end if simp_coeff > max_simp_coeff: max_simp_coeff = simp_coeff simp = (start, _Mul(subterm), p, end, l) pre = pre_argpre_exp post = post_argpost_exp if simp: subterm = _Pow(nc_simplify(simp[1], deep=deep), simp[2]) pre = nc_simplify(_Mul(args[:simp[0]])pre, deep=deep) post = postnc_simplify(_Mul(args[simp[3]:]), deep=deep) simp = presubtermpost if pre != 1 or post != 1: # new simplifications may be possible but no need # to recurse over arguments simp = nc_simplify(simp, deep=False) else: simp = _Mul(args) if invert: simp = _Pow(simp, -1) # see if factor_nc(expr) is simplified better if not isinstance(expr, MatrixExpr): f_expr = factor_nc(expr) if f_expr != expr: alt_simp = nc_simplify(f_expr, deep=deep) simp = compare(simp, alt_simp) else: simp = simp.doit(inv_expand=False) return simp
914aa2ad8da7ec17f8bc81adfac36ab59dd59ff027f746751179165a3a635f5e	from __future__ import print_function, division from collections import defaultdict from sympy import SYMPY_DEBUG from sympy.core import expand_power_base, sympify, Add, S, Mul, Derivative, Pow, symbols, expand_mul from sympy.core.add import _unevaluated_Add from sympy.core.compatibility import iterable, ordered, default_sort_key from sympy.core.evaluate import global_evaluate from sympy.core.exprtools import Factors, gcd_terms from sympy.core.function import _mexpand from sympy.core.mul import _keep_coeff, _unevaluated_Mul from sympy.core.numbers import Rational from sympy.functions import exp, sqrt, log from sympy.polys import gcd from sympy.simplify.sqrtdenest import sqrtdenest def collect(expr, syms, func=None, evaluate=None, exact=False, distribute_order_term=True): """ Collect additive terms of an expression. This function collects additive terms of an expression with respect to a list of expression up to powers with rational exponents. By the term symbol here are meant arbitrary expressions, which can contain powers, products, sums etc. In other words symbol is a pattern which will be searched for in the expression's terms. The input expression is not expanded by :func:`collect`, so user is expected to provide an expression is an appropriate form. This makes :func:`collect` more predictable as there is no magic happening behind the scenes. However, it is important to note, that powers of products are converted to products of powers using the :func:`expand_power_base` function. There are two possible types of output. First, if ``evaluate`` flag is set, this function will return an expression with collected terms or else it will return a dictionary with expressions up to rational powers as keys and collected coefficients as values. Examples ======== >>> from sympy import S, collect, expand, factor, Wild >>> from sympy.abc import a, b, c, x, y, z This function can collect symbolic coefficients in polynomials or rational expressions. It will manage to find all integer or rational powers of collection variable:: >>> collect(ax2 + bx*2 + ax - bx + c, x) c + x2(a + b) + x(a - b) The same result can be achieved in dictionary form:: >>> d = collect(ax*2 + bx*2 + ax - bx + c, x, evaluate=False) >>> d[x2] a + b >>> d[x] a - b >>> d[S.One] c You can also work with multivariate polynomials. However, remember that this function is greedy so it will care only about a single symbol at time, in specification order:: >>> collect(x2 + yx*2 + xy + y + ay, [x, y]) x2(y + 1) + xy + y(a + 1) Also more complicated expressions can be used as patterns:: >>> from sympy import sin, log >>> collect(asin(2x) + bsin(2x), sin(2x)) (a + b)sin(2x) >>> collect(axlog(x) + b(xlog(x)), xlog(x)) x(a + b)log(x) You can use wildcards in the pattern:: >>> w = Wild('w1') >>> collect(axy - bxy, wy) x*y(a - b) It is also possible to work with symbolic powers, although it has more complicated behavior, because in this case power's base and symbolic part of the exponent are treated as a single symbol:: >>> collect(axc + bx*c, x) ax*c + bx*c >>> collect(ax*c + bxc, xc) x*c(a + b) However if you incorporate rationals to the exponents, then you will get well known behavior:: >>> collect(ax(2c) + bx(2c), xc) x(2c)(a + b) Note also that all previously stated facts about :func:`collect` function apply to the exponential function, so you can get:: >>> from sympy import exp >>> collect(aexp(2x) + bexp(2x), exp(x)) (a + b)exp(2x) If you are interested only in collecting specific powers of some symbols then set ``exact`` flag in arguments:: >>> collect(ax7 + bx*7, x, exact=True) ax*7 + bx*7 >>> collect(ax*7 + bx7, x7, exact=True) x*7(a + b) You can also apply this function to differential equations, where derivatives of arbitrary order can be collected. Note that if you collect with respect to a function or a derivative of a function, all derivatives of that function will also be collected. Use ``exact=True`` to prevent this from happening:: >>> from sympy import Derivative as D, collect, Function >>> f = Function('f') (x) >>> collect(aD(f,x) + bD(f,x), D(f,x)) (a + b)Derivative(f(x), x) >>> collect(aD(D(f,x),x) + bD(D(f,x),x), f) (a + b)Derivative(f(x), (x, 2)) >>> collect(aD(D(f,x),x) + bD(D(f,x),x), D(f,x), exact=True) aDerivative(f(x), (x, 2)) + bDerivative(f(x), (x, 2)) >>> collect(aD(f,x) + bD(f,x) + af + bf, f) (a + b)f(x) + (a + b)Derivative(f(x), x) Or you can even match both derivative order and exponent at the same time:: >>> collect(aD(D(f,x),x)2 + bD(D(f,x),x)*2, D(f,x)) (a + b)Derivative(f(x), (x, 2))2 Finally, you can apply a function to each of the collected coefficients. For example you can factorize symbolic coefficients of polynomial:: >>> f = expand((x + a + 1)3) >>> collect(f, x, factor) x*3 + 3x*2(a + 1) + 3x(a + 1)2 + (a + 1)3 .. note:: Arguments are expected to be in expanded form, so you might have to call :func:`expand` prior to calling this function. See Also ======== collect_const, collect_sqrt, rcollect """ expr = sympify(expr) syms = list(syms) if iterable(syms) else [syms] if evaluate is None: evaluate = global_evaluate[0] def make_expression(terms): product = [] for term, rat, sym, deriv in terms: if deriv is not None: var, order = deriv while order > 0: term, order = Derivative(term, var), order - 1 if sym is None: if rat is S.One: product.append(term) else: product.append(Pow(term, rat)) else: product.append(Pow(term, ratsym)) return Mul(product) def parse_derivative(deriv): # scan derivatives tower in the input expression and return # underlying function and maximal differentiation order expr, sym, order = deriv.expr, deriv.variables[0], 1 for s in deriv.variables[1:]: if s == sym: order += 1 else: raise NotImplementedError( 'Improve MV Derivative support in collect') while isinstance(expr, Derivative): s0 = expr.variables[0] for s in expr.variables: if s != s0: raise NotImplementedError( 'Improve MV Derivative support in collect') if s0 == sym: expr, order = expr.expr, order + len(expr.variables) else: break return expr, (sym, Rational(order)) def parse_term(expr): """Parses expression expr and outputs tuple (sexpr, rat_expo, sym_expo, deriv) where: - sexpr is the base expression - rat_expo is the rational exponent that sexpr is raised to - sym_expo is the symbolic exponent that sexpr is raised to - deriv contains the derivatives the the expression for example, the output of x would be (x, 1, None, None) the output of 2*x would be (2, 1, x, None) """ rat_expo, sym_expo = S.One, None sexpr, deriv = expr, None if expr.is_Pow: if isinstance(expr.base, Derivative): sexpr, deriv = parse_derivative(expr.base) else: sexpr = expr.base if expr.exp.is_Number: rat_expo = expr.exp else: coeff, tail = expr.exp.as_coeff_Mul() if coeff.is_Number: rat_expo, sym_expo = coeff, tail else: sym_expo = expr.exp elif isinstance(expr, exp): arg = expr.args[0] if arg.is_Rational: sexpr, rat_expo = S.Exp1, arg elif arg.is_Mul: coeff, tail = arg.as_coeff_Mul(rational=True) sexpr, rat_expo = exp(tail), coeff elif isinstance(expr, Derivative): sexpr, deriv = parse_derivative(expr) return sexpr, rat_expo, sym_expo, deriv def parse_expression(terms, pattern): """Parse terms searching for a pattern. terms is a list of tuples as returned by parse_terms; pattern is an expression treated as a product of factors """ pattern = Mul.make_args(pattern) if len(terms) < len(pattern): # pattern is longer than matched product # so no chance for positive parsing result return None else: pattern = [parse_term(elem) for elem in pattern] terms = terms[:] # need a copy elems, common_expo, has_deriv = [], None, False for elem, e_rat, e_sym, e_ord in pattern: if elem.is_Number and e_rat == 1 and e_sym is None: # a constant is a match for everything continue for j in range(len(terms)): if terms[j] is None: continue term, t_rat, t_sym, t_ord = terms[j] # keeping track of whether one of the terms had # a derivative or not as this will require rebuilding # the expression later if t_ord is not None: has_deriv = True if (term.match(elem) is not None and (t_sym == e_sym or t_sym is not None and e_sym is not None and t_sym.match(e_sym) is not None)): if exact is False: # we don't have to be exact so find common exponent # for both expression's term and pattern's element expo = t_rat / e_rat if common_expo is None: # first time common_expo = expo else: # common exponent was negotiated before so # there is no chance for a pattern match unless # common and current exponents are equal if common_expo != expo: common_expo = 1 else: # we ought to be exact so all fields of # interest must match in every details if e_rat != t_rat or e_ord != t_ord: continue # found common term so remove it from the expression # and try to match next element in the pattern elems.append(terms[j]) terms[j] = None break else: # pattern element not found return None return [_f for _f in terms if _f], elems, common_expo, has_deriv if evaluate: if expr.is_Add: o = expr.getO() or 0 expr = expr.func([ collect(a, syms, func, True, exact, distribute_order_term) for a in expr.args if a != o]) + o elif expr.is_Mul: return expr.func([ collect(term, syms, func, True, exact, distribute_order_term) for term in expr.args]) elif expr.is_Pow: b = collect( expr.base, syms, func, True, exact, distribute_order_term) return Pow(b, expr.exp) syms = [expand_power_base(i, deep=False) for i in syms] order_term = None if distribute_order_term: order_term = expr.getO() if order_term is not None: if order_term.has(syms): order_term = None else: expr = expr.removeO() summa = [expand_power_base(i, deep=False) for i in Add.make_args(expr)] collected, disliked = defaultdict(list), S.Zero for product in summa: c, nc = product.args_cnc(split_1=False) args = list(ordered(c)) + nc terms = [parse_term(i) for i in args] small_first = True for symbol in syms: if SYMPY_DEBUG: print("DEBUG: parsing of expression %s with symbol %s " % ( str(terms), str(symbol)) ) if isinstance(symbol, Derivative) and small_first: terms = list(reversed(terms)) small_first = not small_first result = parse_expression(terms, symbol) if SYMPY_DEBUG: print("DEBUG: returned %s" % str(result)) if result is not None: if not symbol.is_commutative: raise AttributeError("Can not collect noncommutative symbol") terms, elems, common_expo, has_deriv = result # when there was derivative in current pattern we # will need to rebuild its expression from scratch if not has_deriv: margs = [] for elem in elems: if elem[2] is None: e = elem[1] else: e = elem[1]elem[2] margs.append(Pow(elem[0], e)) index = Mul(margs) else: index = make_expression(elems) terms = expand_power_base(make_expression(terms), deep=False) index = expand_power_base(index, deep=False) collected[index].append(terms) break else: # none of the patterns matched disliked += product # add terms now for each key collected = {k: Add(v) for k, v in collected.items()} if disliked is not S.Zero: collected[S.One] = disliked if order_term is not None: for key, val in collected.items(): collected[key] = val + order_term if func is not None: collected = dict( [(key, func(val)) for key, val in collected.items()]) if evaluate: return Add([keyval for key, val in collected.items()]) else: return collected def rcollect(expr, vars): """ Recursively collect sums in an expression. Examples ======== >>> from sympy.simplify import rcollect >>> from sympy.abc import x, y >>> expr = (x*2y + xy + x + y)/(x + y) >>> rcollect(expr, y) (x + y(x*2 + x + 1))/(x + y) See Also ======== collect, collect_const, collect_sqrt """ if expr.is_Atom or not expr.has(vars): return expr else: expr = expr.__class__([rcollect(arg, vars) for arg in expr.args]) if expr.is_Add: return collect(expr, vars) else: return expr def collect_sqrt(expr, evaluate=None): """Return expr with terms having common square roots collected together. If ``evaluate`` is False a count indicating the number of sqrt-containing terms will be returned and, if non-zero, the terms of the Add will be returned, else the expression itself will be returned as a single term. If ``evaluate`` is True, the expression with any collected terms will be returned. Note: since I = sqrt(-1), it is collected, too. Examples ======== >>> from sympy import sqrt >>> from sympy.simplify.radsimp import collect_sqrt >>> from sympy.abc import a, b >>> r2, r3, r5 = [sqrt(i) for i in [2, 3, 5]] >>> collect_sqrt(ar2 + br2) sqrt(2)(a + b) >>> collect_sqrt(ar2 + br2 + ar3 + br3) sqrt(2)(a + b) + sqrt(3)(a + b) >>> collect_sqrt(ar2 + br2 + ar3 + br5) sqrt(3)a + sqrt(5)b + sqrt(2)(a + b) If evaluate is False then the arguments will be sorted and returned as a list and a count of the number of sqrt-containing terms will be returned: >>> collect_sqrt(ar2 + br2 + ar3 + br5, evaluate=False) ((sqrt(3)a, sqrt(5)b, sqrt(2)(a + b)), 3) >>> collect_sqrt(asqrt(2) + b, evaluate=False) ((b, sqrt(2)a), 1) >>> collect_sqrt(a + b, evaluate=False) ((a + b,), 0) See Also ======== collect, collect_const, rcollect """ if evaluate is None: evaluate = global_evaluate[0] # this step will help to standardize any complex arguments # of sqrts coeff, expr = expr.as_content_primitive() vars = set() for a in Add.make_args(expr): for m in a.args_cnc()[0]: if m.is_number and ( m.is_Pow and m.exp.is_Rational and m.exp.q == 2 or m is S.ImaginaryUnit): vars.add(m) # we only want radicals, so exclude Number handling; in this case # d will be evaluated d = collect_const(expr, vars, Numbers=False) hit = expr != d if not evaluate: nrad = 0 # make the evaluated args canonical args = list(ordered(Add.make_args(d))) for i, m in enumerate(args): c, nc = m.args_cnc() for ci in c: # XXX should this be restricted to ci.is_number as above? if ci.is_Pow and ci.exp.is_Rational and ci.exp.q == 2 or \ ci is S.ImaginaryUnit: nrad += 1 break args[i] = coeff if not (hit or nrad): args = [Add(args)] return tuple(args), nrad return coeffd def collect_const(expr, vars, *kwargs): """A non-greedy collection of terms with similar number coefficients in an Add expr. If ``vars`` is given then only those constants will be targeted. Although any Number can also be targeted, if this is not desired set ``Numbers=False`` and no Float or Rational will be collected. Parameters ========== expr : sympy expression This parameter defines the expression the expression from which terms with similar coefficients are to be collected. A non-Add expression is returned as it is. vars : variable length collection of Numbers, optional Specifies the constants to target for collection. Can be multiple in number. kwargs : ``Numbers`` is the only possible argument to pass. Numbers (default=True) specifies to target all instance of :class:`sympy.core.numbers.Number` class. If ``Numbers=False``, then no Float or Rational will be collected. Returns ======= expr : Expr Returns an expression with similar coefficient terms collected. Examples ======== >>> from sympy import sqrt >>> from sympy.abc import a, s, x, y, z >>> from sympy.simplify.radsimp import collect_const >>> collect_const(sqrt(3) + sqrt(3)(1 + sqrt(2))) sqrt(3)(sqrt(2) + 2) >>> collect_const(sqrt(3)s + sqrt(7)s + sqrt(3) + sqrt(7)) (sqrt(3) + sqrt(7))(s + 1) >>> s = sqrt(2) + 2 >>> collect_const(sqrt(3)s + sqrt(3) + sqrt(7)s + sqrt(7)) (sqrt(2) + 3)(sqrt(3) + sqrt(7)) >>> collect_const(sqrt(3)s + sqrt(3) + sqrt(7)s + sqrt(7), sqrt(3)) sqrt(7) + sqrt(3)(sqrt(2) + 3) + sqrt(7)(sqrt(2) + 2) The collection is sign-sensitive, giving higher precedence to the unsigned values: >>> collect_const(x - y - z) x - (y + z) >>> collect_const(-y - z) -(y + z) >>> collect_const(2x - 2y - 2z, 2) 2(x - y - z) >>> collect_const(2x - 2y - 2z, -2) 2x - 2(y + z) See Also ======== collect, collect_sqrt, rcollect """ if not expr.is_Add: return expr recurse = False Numbers = kwargs.get('Numbers', True) if not vars: recurse = True vars = set() for a in expr.args: for m in Mul.make_args(a): if m.is_number: vars.add(m) else: vars = sympify(vars) if not Numbers: vars = [v for v in vars if not v.is_Number] vars = list(ordered(vars)) for v in vars: terms = defaultdict(list) Fv = Factors(v) for m in Add.make_args(expr): f = Factors(m) q, r = f.div(Fv) if r.is_one: # only accept this as a true factor if # it didn't change an exponent from an Integer # to a non-Integer, e.g. 2/sqrt(2) -> sqrt(2) # -- we aren't looking for this sort of change fwas = f.factors.copy() fnow = q.factors if not any(k in fwas and fwas[k].is_Integer and not fnow[k].is_Integer for k in fnow): terms[v].append(q.as_expr()) continue terms[S.One].append(m) args = [] hit = False uneval = False for k in ordered(terms): v = terms[k] if k is S.One: args.extend(v) continue if len(v) > 1: v = Add(v) hit = True if recurse and v != expr: vars.append(v) else: v = v[0] # be careful not to let uneval become True unless # it must be because it's going to be more expensive # to rebuild the expression as an unevaluated one if Numbers and k.is_Number and v.is_Add: args.append(_keep_coeff(k, v, sign=True)) uneval = True else: args.append(kv) if hit: if uneval: expr = _unevaluated_Add(args) else: expr = Add(args) if not expr.is_Add: break return expr def radsimp(expr, symbolic=True, max_terms=4): r""" Rationalize the denominator by removing square roots. Note: the expression returned from radsimp must be used with caution since if the denominator contains symbols, it will be possible to make substitutions that violate the assumptions of the simplification process: that for a denominator matching a + bsqrt(c), a != +/-bsqrt(c). (If there are no symbols, this assumptions is made valid by collecting terms of sqrt(c) so the match variable ``a`` does not contain ``sqrt(c)``.) If you do not want the simplification to occur for symbolic denominators, set ``symbolic`` to False. If there are more than ``max_terms`` radical terms then the expression is returned unchanged. Examples ======== >>> from sympy import radsimp, sqrt, Symbol, denom, pprint, I >>> from sympy import factor_terms, fraction, signsimp >>> from sympy.simplify.radsimp import collect_sqrt >>> from sympy.abc import a, b, c >>> radsimp(1/(2 + sqrt(2))) (-sqrt(2) + 2)/2 >>> x,y = map(Symbol, 'xy') >>> e = ((2 + 2sqrt(2))x + (2 + sqrt(8))y)/(2 + sqrt(2)) >>> radsimp(e) sqrt(2)(x + y) No simplification beyond removal of the gcd is done. One might want to polish the result a little, however, by collecting square root terms: >>> r2 = sqrt(2) >>> r5 = sqrt(5) >>> ans = radsimp(1/(yr2 + xr2 + ar5 + br5)); pprint(ans) ___ ___ ___ ___ \/ 5 a + \/ 5 b - \/ 2 x - \/ 2 y ------------------------------------------ 2 2 2 2 5a + 10ab + 5b - 2x - 4xy - 2y >>> n, d = fraction(ans) >>> pprint(factor_terms(signsimp(collect_sqrt(n))/d, radical=True)) ___ ___ \/ 5 (a + b) - \/ 2 (x + y) ------------------------------------------ 2 2 2 2 5a + 10ab + 5b - 2x - 4xy - 2y If radicals in the denominator cannot be removed or there is no denominator, the original expression will be returned. >>> radsimp(sqrt(2)x + sqrt(2)) sqrt(2)x + sqrt(2) Results with symbols will not always be valid for all substitutions: >>> eq = 1/(a + bsqrt(c)) >>> eq.subs(a, bsqrt(c)) 1/(2bsqrt(c)) >>> radsimp(eq).subs(a, bsqrt(c)) nan If symbolic=False, symbolic denominators will not be transformed (but numeric denominators will still be processed): >>> radsimp(eq, symbolic=False) 1/(a + bsqrt(c)) """ from sympy.simplify.simplify import signsimp syms = symbols("a:d A:D") def _num(rterms): # return the multiplier that will simplify the expression described # by rterms [(sqrt arg, coeff), ... ] a, b, c, d, A, B, C, D = syms if len(rterms) == 2: reps = dict(list(zip([A, a, B, b], [j for i in rterms for j in i]))) return ( sqrt(A)a - sqrt(B)b).xreplace(reps) if len(rterms) == 3: reps = dict(list(zip([A, a, B, b, C, c], [j for i in rterms for j in i]))) return ( (sqrt(A)a + sqrt(B)b - sqrt(C)c)(2sqrt(A)sqrt(B)ab - Aa2 - Bb*2 + Cc*2)).xreplace(reps) elif len(rterms) == 4: reps = dict(list(zip([A, a, B, b, C, c, D, d], [j for i in rterms for j in i]))) return ((sqrt(A)a + sqrt(B)b - sqrt(C)c - sqrt(D)d)(2sqrt(A)sqrt(B)ab - Aa2 - Bb*2 - 2sqrt(C)sqrt(D)cd + Cc*2 + Dd*2)(-8sqrt(A)sqrt(B)sqrt(C)sqrt(D)abcd + A*2a*4 - 2ABa*2b*2 - 2ACa*2c*2 - 2ADa*2d2 + B2b4 - 2BCb*2c*2 - 2BDb*2d2 + C2c4 - 2CDc*2d2 + D2d4)).xreplace(reps) elif len(rterms) == 1: return sqrt(rterms[0][0]) else: raise NotImplementedError def ispow2(d, log2=False): if not d.is_Pow: return False e = d.exp if e.is_Rational and e.q == 2 or symbolic and denom(e) == 2: return True if log2: q = 1 if e.is_Rational: q = e.q elif symbolic: d = denom(e) if d.is_Integer: q = d if q != 1 and log(q, 2).is_Integer: return True return False def handle(expr): # Handle first reduces to the case # expr = 1/d, where d is an add, or d is basep/2. # We do this by recursively calling handle on each piece. from sympy.simplify.simplify import nsimplify n, d = fraction(expr) if expr.is_Atom or (d.is_Atom and n.is_Atom): return expr elif not n.is_Atom: n = n.func([handle(a) for a in n.args]) return _unevaluated_Mul(n, handle(1/d)) elif n is not S.One: return _unevaluated_Mul(n, handle(1/d)) elif d.is_Mul: return _unevaluated_Mul([handle(1/d) for d in d.args]) # By this step, expr is 1/d, and d is not a mul. if not symbolic and d.free_symbols: return expr if ispow2(d): d2 = sqrtdenest(sqrt(d.base))numer(d.exp) if d2 != d: return handle(1/d2) elif d.is_Pow and (d.exp.is_integer or d.base.is_positive): # (1/di) = (1/d)i return handle(1/d.base)d.exp if not (d.is_Add or ispow2(d)): return 1/d.func([handle(a) for a in d.args]) # handle 1/d treating d as an Add (though it may not be) keep = True # keep changes that are made # flatten it and collect radicals after checking for special # conditions d = _mexpand(d) # did it change? if d.is_Atom: return 1/d # is it a number that might be handled easily? if d.is_number: _d = nsimplify(d) if _d.is_Number and _d.equals(d): return 1/_d while True: # collect similar terms collected = defaultdict(list) for m in Add.make_args(d): # d might have become non-Add p2 = [] other = [] for i in Mul.make_args(m): if ispow2(i, log2=True): p2.append(i.base if i.exp is S.Half else i.base*(2i.exp)) elif i is S.ImaginaryUnit: p2.append(S.NegativeOne) else: other.append(i) collected[tuple(ordered(p2))].append(Mul(other)) rterms = list(ordered(list(collected.items()))) rterms = [(Mul(i), Add(j)) for i, j in rterms] nrad = len(rterms) - (1 if rterms[0][0] is S.One else 0) if nrad < 1: break elif nrad > max_terms: # there may have been invalid operations leading to this point # so don't keep changes, e.g. this expression is troublesome # in collecting terms so as not to raise the issue of 2834: # r = sqrt(sqrt(5) + 5) # eq = 1/(sqrt(5)r + 2sqrt(5)sqrt(-sqrt(5) + 5) + 5r) keep = False break if len(rterms) > 4: # in general, only 4 terms can be removed with repeated squaring # but other considerations can guide selection of radical terms # so that radicals are removed if all([x.is_Integer and (y2).is_Rational for x, y in rterms]): nd, d = rad_rationalize(S.One, Add._from_args( [sqrt(x)y for x, y in rterms])) n = nd else: # is there anything else that might be attempted? keep = False break from sympy.simplify.powsimp import powsimp, powdenest num = powsimp(_num(rterms)) n = num d = num d = powdenest(_mexpand(d), force=symbolic) if d.is_Atom: break if not keep: return expr return _unevaluated_Mul(n, 1/d) coeff, expr = expr.as_coeff_Add() expr = expr.normal() old = fraction(expr) n, d = fraction(handle(expr)) if old != (n, d): if not d.is_Atom: was = (n, d) n = signsimp(n, evaluate=False) d = signsimp(d, evaluate=False) u = Factors(_unevaluated_Mul(n, 1/d)) u = _unevaluated_Mul([k*v for k, v in u.factors.items()]) n, d = fraction(u) if old == (n, d): n, d = was n = expand_mul(n) if d.is_Number or d.is_Add: n2, d2 = fraction(gcd_terms(_unevaluated_Mul(n, 1/d))) if d2.is_Number or (d2.count_ops() <= d.count_ops()): n, d = [signsimp(i) for i in (n2, d2)] if n.is_Mul and n.args[0].is_Number: n = n.func(n.args) return coeff + _unevaluated_Mul(n, 1/d) def rad_rationalize(num, den): """ Rationalize num/den by removing square roots in the denominator; num and den are sum of terms whose squares are rationals Examples ======== >>> from sympy import sqrt >>> from sympy.simplify.radsimp import rad_rationalize >>> rad_rationalize(sqrt(3), 1 + sqrt(2)/3) (-sqrt(3) + sqrt(6)/3, -7/9) """ if not den.is_Add: return num, den g, a, b = split_surds(den) a = asqrt(g) num = _mexpand((a - b)num) den = _mexpand(a2 - b2) return rad_rationalize(num, den) def fraction(expr, exact=False): """Returns a pair with expression's numerator and denominator. If the given expression is not a fraction then this function will return the tuple (expr, 1). This function will not make any attempt to simplify nested fractions or to do any term rewriting at all. If only one of the numerator/denominator pair is needed then use numer(expr) or denom(expr) functions respectively. >>> from sympy import fraction, Rational, Symbol >>> from sympy.abc import x, y >>> fraction(x/y) (x, y) >>> fraction(x) (x, 1) >>> fraction(1/y2) (1, y2) >>> fraction(xy/2) (xy, 2) >>> fraction(Rational(1, 2)) (1, 2) This function will also work fine with assumptions: >>> k = Symbol('k', negative=True) >>> fraction(x * yk) (x, y(-k)) If we know nothing about sign of some exponent and 'exact' flag is unset, then structure this exponent's structure will be analyzed and pretty fraction will be returned: >>> from sympy import exp, Mul >>> fraction(2x(-y)) (2, xy) >>> fraction(exp(-x)) (1, exp(x)) >>> fraction(exp(-x), exact=True) (exp(-x), 1) The `exact` flag will also keep any unevaluated Muls from being evaluated: >>> u = Mul(2, x + 1, evaluate=False) >>> fraction(u) (2x + 2, 1) >>> fraction(u, exact=True) (2(x + 1), 1) """ expr = sympify(expr) numer, denom = [], [] for term in Mul.make_args(expr): if term.is_commutative and (term.is_Pow or isinstance(term, exp)): b, ex = term.as_base_exp() if ex.is_negative: if ex is S.NegativeOne: denom.append(b) elif exact: if ex.is_constant(): denom.append(Pow(b, -ex)) else: numer.append(term) else: denom.append(Pow(b, -ex)) elif ex.is_positive: numer.append(term) elif not exact and ex.is_Mul: n, d = term.as_numer_denom() numer.append(n) denom.append(d) else: numer.append(term) elif term.is_Rational: n, d = term.as_numer_denom() numer.append(n) denom.append(d) else: numer.append(term) if exact: return Mul(numer, evaluate=False), Mul(denom, evaluate=False) else: return Mul(numer), Mul(denom) def numer(expr): return fraction(expr)[0] def denom(expr): return fraction(expr)[1] def fraction_expand(expr, hints): return expr.expand(frac=True, hints) def numer_expand(expr, hints): a, b = fraction(expr) return a.expand(numer=True, hints) / b def denom_expand(expr, hints): a, b = fraction(expr) return a / b.expand(denom=True, hints) expand_numer = numer_expand expand_denom = denom_expand expand_fraction = fraction_expand def split_surds(expr): """ split an expression with terms whose squares are rationals into a sum of terms whose surds squared have gcd equal to g and a sum of terms with surds squared prime with g Examples ======== >>> from sympy import sqrt >>> from sympy.simplify.radsimp import split_surds >>> split_surds(3sqrt(3) + sqrt(5)/7 + sqrt(6) + sqrt(10) + sqrt(15)) (3, sqrt(2) + sqrt(5) + 3, sqrt(5)/7 + sqrt(10)) """ args = sorted(expr.args, key=default_sort_key) coeff_muls = [x.as_coeff_Mul() for x in args] surds = [x[1]*2 for x in coeff_muls if x[1].is_Pow] surds.sort(key=default_sort_key) g, b1, b2 = _split_gcd(surds) g2 = g if not b2 and len(b1) >= 2: b1n = [x/g for x in b1] b1n = [x for x in b1n if x != 1] # only a common factor has been factored; split again g1, b1n, b2 = _split_gcd(b1n) g2 = gg1 a1v, a2v = [], [] for c, s in coeff_muls: if s.is_Pow and s.exp == S.Half: s1 = s.base if s1 in b1: a1v.append(csqrt(s1/g2)) else: a2v.append(cs) else: a2v.append(cs) a = Add(a1v) b = Add(a2v) return g2, a, b def _split_gcd(a): """ split the list of integers ``a`` into a list of integers, ``a1`` having ``g = gcd(a1)``, and a list ``a2`` whose elements are not divisible by ``g``. Returns ``g, a1, a2`` Examples ======== >>> from sympy.simplify.radsimp import _split_gcd >>> _split_gcd(55, 35, 22, 14, 77, 10) (5, [55, 35, 10], [22, 14, 77]) """ g = a[0] b1 = [g] b2 = [] for x in a[1:]: g1 = gcd(g, x) if g1 == 1: b2.append(x) else: g = g1 b1.append(x) return g, b1, b2
60e95b5f554a84846332938db6af9d10e202ce355b57242be417693634f0038b	from __future__ import print_function, division from sympy.core import Mul from sympy.core.basic import preorder_traversal from sympy.core.function import count_ops from sympy.functions.combinatorial.factorials import binomial, factorial from sympy.functions import gamma from sympy.simplify.gammasimp import gammasimp, _gammasimp from sympy.utilities.timeutils import timethis @timethis('combsimp') def combsimp(expr): r""" Simplify combinatorial expressions. This function takes as input an expression containing factorials, binomials, Pochhammer symbol and other "combinatorial" functions, and tries to minimize the number of those functions and reduce the size of their arguments. The algorithm works by rewriting all combinatorial functions as gamma functions and applying gammasimp() except simplification steps that may make an integer argument non-integer. See docstring of gammasimp for more information. Then it rewrites expression in terms of factorials and binomials by rewriting gammas as factorials and converting (a+b)!/a!b! into binomials. If expression has gamma functions or combinatorial functions with non-integer argument, it is automatically passed to gammasimp. Examples ======== >>> from sympy.simplify import combsimp >>> from sympy import factorial, binomial, symbols >>> n, k = symbols('n k', integer = True) >>> combsimp(factorial(n)/factorial(n - 3)) n(n - 2)(n - 1) >>> combsimp(binomial(n+1, k+1)/binomial(n, k)) (n + 1)/(k + 1) """ expr = expr.rewrite(gamma) if any(isinstance(node, gamma) and not node.args[0].is_integer for node in preorder_traversal(expr)): return gammasimp(expr); expr = _gammasimp(expr, as_comb = True) expr = _gamma_as_comb(expr) return expr def _gamma_as_comb(expr): """ Helper function for combsimp. Rewrites expression in terms of factorials and binomials """ expr = expr.rewrite(factorial) from .simplify import bottom_up def f(rv): if not rv.is_Mul: return rv rvd = rv.as_powers_dict() nd_fact_args = [[], []] # numerator, denominator for k in rvd: if isinstance(k, factorial) and rvd[k].is_Integer: if rvd[k].is_positive: nd_fact_args[0].extend([k.args[0]]rvd[k]) else: nd_fact_args[1].extend([k.args[0]]-rvd[k]) rvd[k] = 0 if not nd_fact_args[0] or not nd_fact_args[1]: return rv hit = False for m in range(2): i = 0 while i < len(nd_fact_args[m]): ai = nd_fact_args[m][i] for j in range(i + 1, len(nd_fact_args[m])): aj = nd_fact_args[m][j] sum = ai + aj if sum in nd_fact_args[1 - m]: hit = True nd_fact_args[1 - m].remove(sum) del nd_fact_args[m][j] del nd_fact_args[m][i] rvd[binomial(sum, ai if count_ops(ai) < count_ops(aj) else aj)] += ( -1 if m == 0 else 1) break else: i += 1 if hit: return Mul(([krvd[k] for k in rvd] + [factorial(k) for k in nd_fact_args[0]]))/Mul([factorial(k) for k in nd_fact_args[1]]) return rv return bottom_up(expr, f)
1e295b989b10a9dd47b15e9a19723ef94edeb77209af1fb5857302392559260e	from __future__ import print_function, division from sympy.core import S, sympify, Mul, Add, Expr from sympy.core.compatibility import range from sympy.core.function import expand_mul, count_ops, _mexpand from sympy.core.symbol import Dummy from sympy.functions import sqrt, sign, root from sympy.polys import Poly, PolynomialError from sympy.utilities import default_sort_key def is_sqrt(expr): """Return True if expr is a sqrt, otherwise False.""" return expr.is_Pow and expr.exp.is_Rational and abs(expr.exp) is S.Half def sqrt_depth(p): """Return the maximum depth of any square root argument of p. >>> from sympy.functions.elementary.miscellaneous import sqrt >>> from sympy.simplify.sqrtdenest import sqrt_depth Neither of these square roots contains any other square roots so the depth is 1: >>> sqrt_depth(1 + sqrt(2)(1 + sqrt(3))) 1 The sqrt(3) is contained within a square root so the depth is 2: >>> sqrt_depth(1 + sqrt(2)sqrt(1 + sqrt(3))) 2 """ if p.is_Atom: return 0 elif p.is_Add or p.is_Mul: return max([sqrt_depth(x) for x in p.args], key=default_sort_key) elif is_sqrt(p): return sqrt_depth(p.base) + 1 else: return 0 def is_algebraic(p): """Return True if p is comprised of only Rationals or square roots of Rationals and algebraic operations. Examples ======== >>> from sympy.functions.elementary.miscellaneous import sqrt >>> from sympy.simplify.sqrtdenest import is_algebraic >>> from sympy import cos >>> is_algebraic(sqrt(2)(3/(sqrt(7) + sqrt(5)sqrt(2)))) True >>> is_algebraic(sqrt(2)(3/(sqrt(7) + sqrt(5)cos(2)))) False """ if p.is_Rational: return True elif p.is_Atom: return False elif is_sqrt(p) or p.is_Pow and p.exp.is_Integer: return is_algebraic(p.base) elif p.is_Add or p.is_Mul: return all(is_algebraic(x) for x in p.args) else: return False def _subsets(n): """ Returns all possible subsets of the set (0, 1, ..., n-1) except the empty set, listed in reversed lexicographical order according to binary representation, so that the case of the fourth root is treated last. Examples ======== >>> from sympy.simplify.sqrtdenest import _subsets >>> _subsets(2) [[1, 0], [0, 1], [1, 1]] """ if n == 1: a = [[1]] elif n == 2: a = [[1, 0], [0, 1], [1, 1]] elif n == 3: a = [[1, 0, 0], [0, 1, 0], [1, 1, 0], [0, 0, 1], [1, 0, 1], [0, 1, 1], [1, 1, 1]] else: b = _subsets(n - 1) a0 = [x + [0] for x in b] a1 = [x + [1] for x in b] a = a0 + [[0](n - 1) + [1]] + a1 return a def sqrtdenest(expr, max_iter=3): """Denests sqrts in an expression that contain other square roots if possible, otherwise returns the expr unchanged. This is based on the algorithms of [1]. Examples ======== >>> from sympy.simplify.sqrtdenest import sqrtdenest >>> from sympy import sqrt >>> sqrtdenest(sqrt(5 + 2 sqrt(6))) sqrt(2) + sqrt(3) See Also ======== sympy.solvers.solvers.unrad References ========== .. [1] http://researcher.watson.ibm.com/researcher/files/us-fagin/symb85.pdf .. [2] D. J. Jeffrey and A. D. Rich, 'Symplifying Square Roots of Square Roots by Denesting' (available at http://www.cybertester.com/data/denest.pdf) """ expr = expand_mul(sympify(expr)) for i in range(max_iter): z = _sqrtdenest0(expr) if expr == z: return expr expr = z return expr def _sqrt_match(p): """Return [a, b, r] for p.match(a + bsqrt(r)) where, in addition to matching, sqrt(r) also has then maximal sqrt_depth among addends of p. Examples ======== >>> from sympy.functions.elementary.miscellaneous import sqrt >>> from sympy.simplify.sqrtdenest import _sqrt_match >>> _sqrt_match(1 + sqrt(2) + sqrt(2)sqrt(3) + 2sqrt(1+sqrt(5))) [1 + sqrt(2) + sqrt(6), 2, 1 + sqrt(5)] """ from sympy.simplify.radsimp import split_surds p = _mexpand(p) if p.is_Number: res = (p, S.Zero, S.Zero) elif p.is_Add: pargs = sorted(p.args, key=default_sort_key) if all((x2).is_Rational for x in pargs): r, b, a = split_surds(p) res = a, b, r return list(res) # to make the process canonical, the argument is included in the tuple # so when the max is selected, it will be the largest arg having a # given depth v = [(sqrt_depth(x), x, i) for i, x in enumerate(pargs)] nmax = max(v, key=default_sort_key) if nmax[0] == 0: res = [] else: # select r depth, _, i = nmax r = pargs.pop(i) v.pop(i) b = S.One if r.is_Mul: bv = [] rv = [] for x in r.args: if sqrt_depth(x) < depth: bv.append(x) else: rv.append(x) b = Mul._from_args(bv) r = Mul._from_args(rv) # collect terms comtaining r a1 = [] b1 = [b] for x in v: if x[0] < depth: a1.append(x[1]) else: x1 = x[1] if x1 == r: b1.append(1) else: if x1.is_Mul: x1args = list(x1.args) if r in x1args: x1args.remove(r) b1.append(Mul(x1args)) else: a1.append(x[1]) else: a1.append(x[1]) a = Add(a1) b = Add(b1) res = (a, b, r2) else: b, r = p.as_coeff_Mul() if is_sqrt(r): res = (S.Zero, b, r2) else: res = [] return list(res) class SqrtdenestStopIteration(StopIteration): pass def _sqrtdenest0(expr): """Returns expr after denesting its arguments.""" if is_sqrt(expr): n, d = expr.as_numer_denom() if d is S.One: # n is a square root if n.base.is_Add: args = sorted(n.base.args, key=default_sort_key) if len(args) > 2 and all((x*2).is_Integer for x in args): try: return _sqrtdenest_rec(n) except SqrtdenestStopIteration: pass expr = sqrt(_mexpand(Add([_sqrtdenest0(x) for x in args]))) return _sqrtdenest1(expr) else: n, d = [_sqrtdenest0(i) for i in (n, d)] return n/d if isinstance(expr, Add): cs = [] args = [] for arg in expr.args: c, a = arg.as_coeff_Mul() cs.append(c) args.append(a) if all(c.is_Rational for c in cs) and all(is_sqrt(arg) for arg in args): return _sqrt_ratcomb(cs, args) if isinstance(expr, Expr): args = expr.args if args: return expr.func([_sqrtdenest0(a) for a in args]) return expr def _sqrtdenest_rec(expr): """Helper that denests the square root of three or more surds. It returns the denested expression; if it cannot be denested it throws SqrtdenestStopIteration Algorithm: expr.base is in the extension Q_m = Q(sqrt(r_1),..,sqrt(r_k)); split expr.base = a + bsqrt(r_k), where `a` and `b` are on Q_(m-1) = Q(sqrt(r_1),..,sqrt(r_(k-1))); then a2 - b2r_k is on Q_(m-1); denest sqrt(a2 - b2r_k) and so on. See [1], section 6. Examples ======== >>> from sympy import sqrt >>> from sympy.simplify.sqrtdenest import _sqrtdenest_rec >>> _sqrtdenest_rec(sqrt(-72sqrt(2) + 158sqrt(5) + 498)) -sqrt(10) + sqrt(2) + 9 + 9sqrt(5) >>> w=-6sqrt(55)-6sqrt(35)-2sqrt(22)-2sqrt(14)+2sqrt(77)+6sqrt(10)+65 >>> _sqrtdenest_rec(sqrt(w)) -sqrt(11) - sqrt(7) + sqrt(2) + 3sqrt(5) """ from sympy.simplify.radsimp import radsimp, rad_rationalize, split_surds if not expr.is_Pow: return sqrtdenest(expr) if expr.base < 0: return sqrt(-1)_sqrtdenest_rec(sqrt(-expr.base)) g, a, b = split_surds(expr.base) a = asqrt(g) if a < b: a, b = b, a c2 = _mexpand(a2 - b2) if len(c2.args) > 2: g, a1, b1 = split_surds(c2) a1 = a1sqrt(g) if a1 < b1: a1, b1 = b1, a1 c2_1 = _mexpand(a12 - b12) c_1 = _sqrtdenest_rec(sqrt(c2_1)) d_1 = _sqrtdenest_rec(sqrt(a1 + c_1)) num, den = rad_rationalize(b1, d_1) c = _mexpand(d_1/sqrt(2) + num/(densqrt(2))) else: c = _sqrtdenest1(sqrt(c2)) if sqrt_depth(c) > 1: raise SqrtdenestStopIteration ac = a + c if len(ac.args) >= len(expr.args): if count_ops(ac) >= count_ops(expr.base): raise SqrtdenestStopIteration d = sqrtdenest(sqrt(ac)) if sqrt_depth(d) > 1: raise SqrtdenestStopIteration num, den = rad_rationalize(b, d) r = d/sqrt(2) + num/(densqrt(2)) r = radsimp(r) return _mexpand(r) def _sqrtdenest1(expr, denester=True): """Return denested expr after denesting with simpler methods or, that failing, using the denester.""" from sympy.simplify.simplify import radsimp if not is_sqrt(expr): return expr a = expr.base if a.is_Atom: return expr val = _sqrt_match(a) if not val: return expr a, b, r = val # try a quick numeric denesting d2 = _mexpand(a2 - b2r) if d2.is_Rational: if d2.is_positive: z = _sqrt_numeric_denest(a, b, r, d2) if z is not None: return z else: # fourth root case # sqrtdenest(sqrt(3 + 2sqrt(3))) = # sqrt(2)3*(1/4)/2 + sqrt(2)3*(3/4)/2 dr2 = _mexpand(-d2r) dr = sqrt(dr2) if dr.is_Rational: z = _sqrt_numeric_denest(_mexpand(br), a, r, dr2) if z is not None: return z/root(r, 4) else: z = _sqrt_symbolic_denest(a, b, r) if z is not None: return z if not denester or not is_algebraic(expr): return expr res = sqrt_biquadratic_denest(expr, a, b, r, d2) if res: return res # now call to the denester av0 = [a, b, r, d2] z = _denester([radsimp(expr2)], av0, 0, sqrt_depth(expr))[0] if av0[1] is None: return expr if z is not None: if sqrt_depth(z) == sqrt_depth(expr) and count_ops(z) > count_ops(expr): return expr return z return expr def _sqrt_symbolic_denest(a, b, r): """Given an expression, sqrt(a + bsqrt(b)), return the denested expression or None. Algorithm: If r = ra + rbsqrt(rr), try replacing sqrt(rr) in ``a`` with (y2 - ra)/rb, and if the result is a quadratic, cay*2 + cby + cc, and (cb + b)*2 - 4cacc is 0, then sqrt(a + bsqrt(r)) can be rewritten as sqrt(ca(sqrt(r) + (cb + b)/(2ca))*2). Examples ======== >>> from sympy.simplify.sqrtdenest import _sqrt_symbolic_denest, sqrtdenest >>> from sympy import sqrt, Symbol >>> from sympy.abc import x >>> a, b, r = 16 - 2sqrt(29), 2, -10sqrt(29) + 55 >>> _sqrt_symbolic_denest(a, b, r) sqrt(-2sqrt(29) + 11) + sqrt(5) If the expression is numeric, it will be simplified: >>> w = sqrt(sqrt(sqrt(3) + 1) + 1) + 1 + sqrt(2) >>> sqrtdenest(sqrt((w2).expand())) 1 + sqrt(2) + sqrt(1 + sqrt(1 + sqrt(3))) Otherwise, it will only be simplified if assumptions allow: >>> w = w.subs(sqrt(3), sqrt(x + 3)) >>> sqrtdenest(sqrt((w2).expand())) sqrt((sqrt(sqrt(sqrt(x + 3) + 1) + 1) + 1 + sqrt(2))2) Notice that the argument of the sqrt is a square. If x is made positive then the sqrt of the square is resolved: >>> _.subs(x, Symbol('x', positive=True)) sqrt(sqrt(sqrt(x + 3) + 1) + 1) + 1 + sqrt(2) """ a, b, r = map(sympify, (a, b, r)) rval = _sqrt_match(r) if not rval: return None ra, rb, rr = rval if rb: y = Dummy('y', positive=True) try: newa = Poly(a.subs(sqrt(rr), (y2 - ra)/rb), y) except PolynomialError: return None if newa.degree() == 2: ca, cb, cc = newa.all_coeffs() cb += b if _mexpand(cb*2 - 4cacc).equals(0): z = sqrt(ca(sqrt(r) + cb/(2ca))2) if z.is_number: z = _mexpand(Mul._from_args(z.as_content_primitive())) return z def _sqrt_numeric_denest(a, b, r, d2): """Helper that denest expr = a + bsqrt(r), with d2 = a2 - b2r > 0 or returns None if not denested. """ from sympy.simplify.simplify import radsimp depthr = sqrt_depth(r) d = sqrt(d2) vad = a + d # sqrt_depth(res) <= sqrt_depth(vad) + 1 # sqrt_depth(expr) = depthr + 2 # there is denesting if sqrt_depth(vad)+1 < depthr + 2 # if vad2 is Number there is a fourth root if sqrt_depth(vad) < depthr + 1 or (vad2).is_Rational: vad1 = radsimp(1/vad) return (sqrt(vad/2) + sign(b)sqrt((b*2rvad1/2).expand())).expand() def sqrt_biquadratic_denest(expr, a, b, r, d2): """denest expr = sqrt(a + bsqrt(r)) where a, b, r are linear combinations of square roots of positive rationals on the rationals (SQRR) and r > 0, b != 0, d2 = a2 - b2r > 0 If it cannot denest it returns None. ALGORITHM Search for a solution A of type SQRR of the biquadratic equation 4A*4 - 4aA2 + b2r = 0 (1) sqd = sqrt(a2 - b2r) Choosing the sqrt to be positive, the possible solutions are A = sqrt(a/2 +/- sqd/2) Since a, b, r are SQRR, then a2 - b2r is a SQRR, so if sqd can be denested, it is done by _sqrtdenest_rec, and the result is a SQRR. Similarly for A. Examples of solutions (in both cases a and sqd are positive): Example of expr with solution sqrt(a/2 + sqd/2) but not solution sqrt(a/2 - sqd/2): expr = sqrt(-sqrt(15) - sqrt(2)sqrt(-sqrt(5) + 5) - sqrt(3) + 8) a = -sqrt(15) - sqrt(3) + 8; sqd = -2sqrt(5) - 2 + 4sqrt(3) Example of expr with solution sqrt(a/2 - sqd/2) but not solution sqrt(a/2 + sqd/2): w = 2 + r2 + r3 + (1 + r3)sqrt(2 + r2 + 5r3) expr = sqrt((w2).expand()) a = 4sqrt(6) + 8sqrt(2) + 47 + 28sqrt(3) sqd = 29 + 20sqrt(3) Define B = b/2A; eq.(1) implies a = A2 + B2r; then expr2 = a + bsqrt(r) = (A + Bsqrt(r))2 Examples ======== >>> from sympy import sqrt >>> from sympy.simplify.sqrtdenest import _sqrt_match, sqrt_biquadratic_denest >>> z = sqrt((2sqrt(2) + 4)sqrt(2 + sqrt(2)) + 5sqrt(2) + 8) >>> a, b, r = _sqrt_match(z2) >>> d2 = a2 - b*2r >>> sqrt_biquadratic_denest(z, a, b, r, d2) sqrt(2) + sqrt(sqrt(2) + 2) + 2 """ from sympy.simplify.radsimp import radsimp, rad_rationalize if r <= 0 or d2 < 0 or not b or sqrt_depth(expr.base) < 2: return None for x in (a, b, r): for y in x.args: y2 = y*2 if not y2.is_Integer or not y2.is_positive: return None sqd = _mexpand(sqrtdenest(sqrt(radsimp(d2)))) if sqrt_depth(sqd) > 1: return None x1, x2 = [a/2 + sqd/2, a/2 - sqd/2] # look for a solution A with depth 1 for x in (x1, x2): A = sqrtdenest(sqrt(x)) if sqrt_depth(A) > 1: continue Bn, Bd = rad_rationalize(b, _mexpand(2A)) B = Bn/Bd z = A + Bsqrt(r) if z < 0: z = -z return _mexpand(z) return None def _denester(nested, av0, h, max_depth_level): """Denests a list of expressions that contain nested square roots. Algorithm based on <http://www.almaden.ibm.com/cs/people/fagin/symb85.pdf>. It is assumed that all of the elements of 'nested' share the same bottom-level radicand. (This is stated in the paper, on page 177, in the paragraph immediately preceding the algorithm.) When evaluating all of the arguments in parallel, the bottom-level radicand only needs to be denested once. This means that calling _denester with x arguments results in a recursive invocation with x+1 arguments; hence _denester has polynomial complexity. However, if the arguments were evaluated separately, each call would result in two recursive invocations, and the algorithm would have exponential complexity. This is discussed in the paper in the middle paragraph of page 179. """ from sympy.simplify.simplify import radsimp if h > max_depth_level: return None, None if av0[1] is None: return None, None if (av0[0] is None and all(n.is_Number for n in nested)): # no arguments are nested for f in _subsets(len(nested)): # test subset 'f' of nested p = _mexpand(Mul([nested[i] for i in range(len(f)) if f[i]])) if f.count(1) > 1 and f[-1]: p = -p sqp = sqrt(p) if sqp.is_Rational: return sqp, f # got a perfect square so return its square root. # Otherwise, return the radicand from the previous invocation. return sqrt(nested[-1]), [0]len(nested) else: R = None if av0[0] is not None: values = [av0[:2]] R = av0[2] nested2 = [av0[3], R] av0[0] = None else: values = list(filter(None, [_sqrt_match(expr) for expr in nested])) for v in values: if v[2]: # Since if b=0, r is not defined if R is not None: if R != v[2]: av0[1] = None return None, None else: R = v[2] if R is None: # return the radicand from the previous invocation return sqrt(nested[-1]), [0]len(nested) nested2 = [_mexpand(v[0]*2) - _mexpand(Rv[1]*2) for v in values] + [R] d, f = _denester(nested2, av0, h + 1, max_depth_level) if not f: return None, None if not any(f[i] for i in range(len(nested))): v = values[-1] return sqrt(v[0] + _mexpand(v[1]d)), f else: p = Mul([nested[i] for i in range(len(nested)) if f[i]]) v = _sqrt_match(p) if 1 in f and f.index(1) < len(nested) - 1 and f[len(nested) - 1]: v[0] = -v[0] v[1] = -v[1] if not f[len(nested)]: # Solution denests with square roots vad = _mexpand(v[0] + d) if vad <= 0: # return the radicand from the previous invocation. return sqrt(nested[-1]), [0]len(nested) if not(sqrt_depth(vad) <= sqrt_depth(R) + 1 or (vad*2).is_Number): av0[1] = None return None, None sqvad = _sqrtdenest1(sqrt(vad), denester=False) if not (sqrt_depth(sqvad) <= sqrt_depth(R) + 1): av0[1] = None return None, None sqvad1 = radsimp(1/sqvad) res = _mexpand(sqvad/sqrt(2) + (v[1]sqrt(R)sqvad1/sqrt(2))) return res, f # sign(v[1])sqrt(_mexpand(v[1]*2Rvad1/2))), f else: # Solution requires a fourth root s2 = _mexpand(v[1]R) + d if s2 <= 0: return sqrt(nested[-1]), [0]len(nested) FR, s = root(_mexpand(R), 4), sqrt(s2) return _mexpand(s/(sqrt(2)FR) + v[0]FR/(sqrt(2)s)), f def _sqrt_ratcomb(cs, args): """Denest rational combinations of radicals. Based on section 5 of [1]. Examples ======== >>> from sympy import sqrt >>> from sympy.simplify.sqrtdenest import sqrtdenest >>> z = sqrt(1+sqrt(3)) + sqrt(3+3sqrt(3)) - sqrt(10+6sqrt(3)) >>> sqrtdenest(z) 0 """ from sympy.simplify.radsimp import radsimp # check if there exists a pair of sqrt that can be denested def find(a): n = len(a) for i in range(n - 1): for j in range(i + 1, n): s1 = a[i].base s2 = a[j].base p = _mexpand(s1 * s2) s = sqrtdenest(sqrt(p)) if s != sqrt(p): return s, i, j indices = find(args) if indices is None: return Add([c arg for c, arg in zip(cs, args)]) s, i1, i2 = indices c2 = cs.pop(i2) args.pop(i2) a1 = args[i1] # replace a2 by s/a1 cs[i1] += radsimp(c2 * s / a1.base) return _sqrt_ratcomb(cs, args)
56d18a397c43380f2c040fbd767e49a2b7f533fc690579c7cb1e34b225e64f8e	from __future__ import print_function, division from sympy.core import Function, S, Mul, Pow, Add from sympy.core.compatibility import ordered, default_sort_key from sympy.core.function import count_ops, expand_func from sympy.functions.combinatorial.factorials import binomial from sympy.functions import gamma, sqrt, sin from sympy.polys import factor, cancel from sympy.utilities.iterables import sift, uniq def gammasimp(expr): r""" Simplify expressions with gamma functions. This function takes as input an expression containing gamma functions or functions that can be rewritten in terms of gamma functions and tries to minimize the number of those functions and reduce the size of their arguments. The algorithm works by rewriting all gamma functions as expressions involving rising factorials (Pochhammer symbols) and applies recurrence relations and other transformations applicable to rising factorials, to reduce their arguments, possibly letting the resulting rising factorial to cancel. Rising factorials with the second argument being an integer are expanded into polynomial forms and finally all other rising factorial are rewritten in terms of gamma functions. Then the following two steps are performed. 1. Reduce the number of gammas by applying the reflection theorem gamma(x)gamma(1-x) == pi/sin(pix). 2. Reduce the number of gammas by applying the multiplication theorem gamma(x)gamma(x+1/n)...gamma(x+(n-1)/n) == Cgamma(nx). It then reduces the number of prefactors by absorbing them into gammas where possible and expands gammas with rational argument. All transformation rules can be found (or was derived from) here: 1. http://functions.wolfram.com/GammaBetaErf/Pochhammer/17/01/02/ 2. http://functions.wolfram.com/GammaBetaErf/Pochhammer/27/01/0005/ Examples ======== >>> from sympy.simplify import gammasimp >>> from sympy import gamma, factorial, Symbol >>> from sympy.abc import x >>> n = Symbol('n', integer = True) >>> gammasimp(gamma(x)/gamma(x - 3)) (x - 3)(x - 2)(x - 1) >>> gammasimp(gamma(n + 3)) gamma(n + 3) """ expr = expr.rewrite(gamma) return _gammasimp(expr, as_comb = False) def _gammasimp(expr, as_comb): """ Helper function for gammasimp and combsimp. Simplifies expressions written in terms of gamma function. If as_comb is True, it tries to preserve integer arguments. See docstring of gammasimp for more information. This was part of combsimp() in combsimp.py. """ expr = expr.replace(gamma, lambda n: _rf(1, (n - 1).expand())) if as_comb: expr = expr.replace(_rf, lambda a, b: gamma(b + 1)) else: expr = expr.replace(_rf, lambda a, b: gamma(a + b)/gamma(a)) def rule(n, k): coeff, rewrite = S.One, False cn, _n = n.as_coeff_Add() if _n and cn.is_Integer and cn: coeff = _rf(_n + 1, cn)/_rf(_n - k + 1, cn) rewrite = True n = _n # this sort of binomial has already been removed by # rising factorials but is left here in case the order # of rule application is changed if k.is_Add: ck, _k = k.as_coeff_Add() if _k and ck.is_Integer and ck: coeff = _rf(n - ck - _k + 1, ck)/_rf(_k + 1, ck) rewrite = True k = _k if count_ops(k) > count_ops(n - k): rewrite = True k = n - k if rewrite: return coeffbinomial(n, k) expr = expr.replace(binomial, rule) def rule_gamma(expr, level=0): """ Simplify products of gamma functions further. """ if expr.is_Atom: return expr def gamma_rat(x): # helper to simplify ratios of gammas was = x.count(gamma) xx = x.replace(gamma, lambda n: _rf(1, (n - 1).expand() ).replace(_rf, lambda a, b: gamma(a + b)/gamma(a))) if xx.count(gamma) < was: x = xx return x def gamma_factor(x): # return True if there is a gamma factor in shallow args if isinstance(x, gamma): return True if x.is_Add or x.is_Mul: return any(gamma_factor(xi) for xi in x.args) if x.is_Pow and (x.exp.is_integer or x.base.is_positive): return gamma_factor(x.base) return False # recursion step if level == 0: expr = expr.func([rule_gamma(x, level + 1) for x in expr.args]) level += 1 if not expr.is_Mul: return expr # non-commutative step if level == 1: args, nc = expr.args_cnc() if not args: return expr if nc: return rule_gamma(Mul._from_args(args), level + 1)Mul._from_args(nc) level += 1 # pure gamma handling, not factor absorption if level == 2: T, F = sift(expr.args, gamma_factor, binary=True) gamma_ind = Mul(F) d = Mul(T) nd, dd = d.as_numer_denom() for ipass in range(2): args = list(ordered(Mul.make_args(nd))) for i, ni in enumerate(args): if ni.is_Add: ni, dd = Add([ rule_gamma(gamma_rat(a/dd), level + 1) for a in ni.args] ).as_numer_denom() args[i] = ni if not dd.has(gamma): break nd = Mul(args) if ipass == 0 and not gamma_factor(nd): break nd, dd = dd, nd # now process in reversed order expr = gamma_indnd/dd if not (expr.is_Mul and (gamma_factor(dd) or gamma_factor(nd))): return expr level += 1 # iteration until constant if level == 3: while True: was = expr expr = rule_gamma(expr, 4) if expr == was: return expr numer_gammas = [] denom_gammas = [] numer_others = [] denom_others = [] def explicate(p): if p is S.One: return None, [] b, e = p.as_base_exp() if e.is_Integer: if isinstance(b, gamma): return True, [b.args[0]]e else: return False, [b]e else: return False, [p] newargs = list(ordered(expr.args)) while newargs: n, d = newargs.pop().as_numer_denom() isg, l = explicate(n) if isg: numer_gammas.extend(l) elif isg is False: numer_others.extend(l) isg, l = explicate(d) if isg: denom_gammas.extend(l) elif isg is False: denom_others.extend(l) # =========== level 2 work: pure gamma manipulation ========= if not as_comb: # Try to reduce the number of gamma factors by applying the # reflection formula gamma(x)gamma(1-x) = pi/sin(pix) for gammas, numer, denom in [( numer_gammas, numer_others, denom_others), (denom_gammas, denom_others, numer_others)]: new = [] while gammas: g1 = gammas.pop() if g1.is_integer: new.append(g1) continue for i, g2 in enumerate(gammas): n = g1 + g2 - 1 if not n.is_Integer: continue numer.append(S.Pi) denom.append(sin(S.Pig1)) gammas.pop(i) if n > 0: for k in range(n): numer.append(1 - g1 + k) elif n < 0: for k in range(-n): denom.append(-g1 - k) break else: new.append(g1) # /!\ updating IN PLACE gammas[:] = new # Try to reduce the number of gammas by using the duplication # theorem to cancel an upper and lower: gamma(2s)/gamma(s) = # 2(2s + 1)/(4sqrt(pi))gamma(s + 1/2). Although this could # be done with higher argument ratios like gamma(3x)/gamma(x), # this would not reduce the number of gammas as in this case. for ng, dg, no, do in [(numer_gammas, denom_gammas, numer_others, denom_others), (denom_gammas, numer_gammas, denom_others, numer_others)]: while True: for x in ng: for y in dg: n = x - 2y if n.is_Integer: break else: continue break else: break ng.remove(x) dg.remove(y) if n > 0: for k in range(n): no.append(2y + k) elif n < 0: for k in range(-n): do.append(2y - 1 - k) ng.append(y + S(1)/2) no.append(2*(2y - 1)) do.append(sqrt(S.Pi)) # Try to reduce the number of gamma factors by applying the # multiplication theorem (used when n gammas with args differing # by 1/n mod 1 are encountered). # # run of 2 with args differing by 1/2 # # >>> gammasimp(gamma(x)gamma(x+S.Half)) # 2sqrt(2)2(-2x - 1/2)sqrt(pi)gamma(2x) # # run of 3 args differing by 1/3 (mod 1) # # >>> gammasimp(gamma(x)gamma(x+S(1)/3)gamma(x+S(2)/3)) # 63*(-3x - 1/2)pigamma(3x) # >>> gammasimp(gamma(x)gamma(x+S(1)/3)gamma(x+S(5)/3)) # 23*(-3x - 1/2)pi(3x + 2)gamma(3x) # def _run(coeffs): # find runs in coeffs such that the difference in terms (mod 1) # of t1, t2, ..., tn is 1/n u = list(uniq(coeffs)) for i in range(len(u)): dj = ([((u[j] - u[i]) % 1, j) for j in range(i + 1, len(u))]) for one, j in dj: if one.p == 1 and one.q != 1: n = one.q got = [i] get = list(range(1, n)) for d, j in dj: m = nd if m.is_Integer and m in get: get.remove(m) got.append(j) if not get: break else: continue for i, j in enumerate(got): c = u[j] coeffs.remove(c) got[i] = c return one.q, got[0], got[1:] def _mult_thm(gammas, numer, denom): # pull off and analyze the leading coefficient from each gamma arg # looking for runs in those Rationals # expr -> coeff + resid -> rats[resid] = coeff rats = {} for g in gammas: c, resid = g.as_coeff_Add() rats.setdefault(resid, []).append(c) # look for runs in Rationals for each resid keys = sorted(rats, key=default_sort_key) for resid in keys: coeffs = list(sorted(rats[resid])) new = [] while True: run = _run(coeffs) if run is None: break # process the sequence that was found: # 1) convert all the gamma functions to have the right # argument (could be off by an integer) # 2) append the factors corresponding to the theorem # 3) append the new gamma function n, ui, other = run # (1) for u in other: con = resid + u - 1 for k in range(int(u - ui)): numer.append(con - k) con = n(resid + ui) # for (2) and (3) # (2) numer.append((2S.Pi)*(S(n - 1)/2) n*(S(1)/2 - con)) # (3) new.append(con) # restore resid to coeffs rats[resid] = [resid + c for c in coeffs] + new # rebuild the gamma arguments g = [] for resid in keys: g += rats[resid] # /!\ updating IN PLACE gammas[:] = g for l, numer, denom in [(numer_gammas, numer_others, denom_others), (denom_gammas, denom_others, numer_others)]: _mult_thm(l, numer, denom) # =========== level >= 2 work: factor absorption ========= if level >= 2: # Try to absorb factors into the gammas: xgamma(x) -> gamma(x + 1) # and gamma(x)/(x - 1) -> gamma(x - 1) # This code (in particular repeated calls to find_fuzzy) can be very # slow. def find_fuzzy(l, x): if not l: return S1, T1 = compute_ST(x) for y in l: S2, T2 = inv[y] if T1 != T2 or (not S1.intersection(S2) and (S1 != set() or S2 != set())): continue # XXX we want some simplification (e.g. cancel or # simplify) but no matter what it's slow. a = len(cancel(x/y).free_symbols) b = len(x.free_symbols) c = len(y.free_symbols) # TODO is there a better heuristic? if a == 0 and (b > 0 or c > 0): return y # We thus try to avoid expensive calls by building the following # "invariants": For every factor or gamma function argument # - the set of free symbols S # - the set of functional components T # We will only try to absorb if T1==T2 and (S1 intersect S2 != emptyset # or S1 == S2 == emptyset) inv = {} def compute_ST(expr): if expr in inv: return inv[expr] return (expr.free_symbols, expr.atoms(Function).union( set(e.exp for e in expr.atoms(Pow)))) def update_ST(expr): inv[expr] = compute_ST(expr) for expr in numer_gammas + denom_gammas + numer_others + denom_others: update_ST(expr) for gammas, numer, denom in [( numer_gammas, numer_others, denom_others), (denom_gammas, denom_others, numer_others)]: new = [] while gammas: g = gammas.pop() cont = True while cont: cont = False y = find_fuzzy(numer, g) if y is not None: numer.remove(y) if y != g: numer.append(y/g) update_ST(y/g) g += 1 cont = True y = find_fuzzy(denom, g - 1) if y is not None: denom.remove(y) if y != g - 1: numer.append((g - 1)/y) update_ST((g - 1)/y) g -= 1 cont = True new.append(g) # /!\ updating IN PLACE gammas[:] = new # =========== rebuild expr ================================== return Mul([gamma(g) for g in numer_gammas]) \ / Mul([gamma(g) for g in denom_gammas]) \ * Mul(numer_others) / Mul(denom_others) # (for some reason we cannot use Basic.replace in this case) was = factor(expr) expr = rule_gamma(was) if expr != was: expr = factor(expr) expr = expr.replace(gamma, lambda n: expand_func(gamma(n)) if n.is_Rational else gamma(n)) return expr class _rf(Function): @classmethod def eval(cls, a, b): if b.is_Integer: if not b: return S.One n, result = int(b), S.One if n > 0: for i in range(n): result = a + i return result elif n < 0: for i in range(1, -n + 1): result = a - i return 1/result else: if b.is_Add: c, _b = b.as_coeff_Add() if c.is_Integer: if c > 0: return _rf(a, _b)_rf(a + _b, c) elif c < 0: return _rf(a, _b)/_rf(a + _b + c, -c) if a.is_Add: c, _a = a.as_coeff_Add() if c.is_Integer: if c > 0: return _rf(_a, b)_rf(_a + b, c)/_rf(_a, c) elif c < 0: return _rf(_a, b)*_rf(_a + c, -c)/_rf(_a + b + c, -c)
915f0c36208115b19dd4e2d7f4ef7046fbb64ce4bf9588c6d6fa22ce838fa03f	from __future__ import print_function, division from collections import defaultdict from sympy.core import (sympify, Basic, S, Expr, expand_mul, factor_terms, Mul, Dummy, igcd, FunctionClass, Add, symbols, Wild, expand) from sympy.core.cache import cacheit from sympy.core.compatibility import reduce, iterable, SYMPY_INTS from sympy.core.function import count_ops, _mexpand from sympy.core.numbers import I, Integer from sympy.functions import sin, cos, exp, cosh, tanh, sinh, tan, cot, coth from sympy.functions.elementary.hyperbolic import HyperbolicFunction from sympy.functions.elementary.trigonometric import TrigonometricFunction from sympy.polys import Poly, factor, cancel, parallel_poly_from_expr from sympy.polys.domains import ZZ from sympy.polys.polyerrors import PolificationFailed from sympy.polys.polytools import groebner from sympy.simplify.cse_main import cse from sympy.strategies.core import identity from sympy.strategies.tree import greedy from sympy.utilities.misc import debug def trigsimp_groebner(expr, hints=[], quick=False, order="grlex", polynomial=False): """ Simplify trigonometric expressions using a groebner basis algorithm. This routine takes a fraction involving trigonometric or hyperbolic expressions, and tries to simplify it. The primary metric is the total degree. Some attempts are made to choose the simplest possible expression of the minimal degree, but this is non-rigorous, and also very slow (see the ``quick=True`` option). If ``polynomial`` is set to True, instead of simplifying numerator and denominator together, this function just brings numerator and denominator into a canonical form. This is much faster, but has potentially worse results. However, if the input is a polynomial, then the result is guaranteed to be an equivalent polynomial of minimal degree. The most important option is hints. Its entries can be any of the following: - a natural number - a function - an iterable of the form (func, var1, var2, ...) - anything else, interpreted as a generator A number is used to indicate that the search space should be increased. A function is used to indicate that said function is likely to occur in a simplified expression. An iterable is used indicate that func(var1 + var2 + ...) is likely to occur in a simplified . An additional generator also indicates that it is likely to occur. (See examples below). This routine carries out various computationally intensive algorithms. The option ``quick=True`` can be used to suppress one particularly slow step (at the expense of potentially more complicated results, but never at the expense of increased total degree). Examples ======== >>> from sympy.abc import x, y >>> from sympy import sin, tan, cos, sinh, cosh, tanh >>> from sympy.simplify.trigsimp import trigsimp_groebner Suppose you want to simplify ``sin(x)cos(x)``. Naively, nothing happens: >>> ex = sin(x)cos(x) >>> trigsimp_groebner(ex) sin(x)cos(x) This is because ``trigsimp_groebner`` only looks for a simplification involving just ``sin(x)`` and ``cos(x)``. You can tell it to also try ``2x`` by passing ``hints=[2]``: >>> trigsimp_groebner(ex, hints=[2]) sin(2x)/2 >>> trigsimp_groebner(sin(x)2 - cos(x)2, hints=[2]) -cos(2x) Increasing the search space this way can quickly become expensive. A much faster way is to give a specific expression that is likely to occur: >>> trigsimp_groebner(ex, hints=[sin(2x)]) sin(2x)/2 Hyperbolic expressions are similarly supported: >>> trigsimp_groebner(sinh(2x)/sinh(x)) 2cosh(x) Note how no hints had to be passed, since the expression already involved ``2x``. The tangent function is also supported. You can either pass ``tan`` in the hints, to indicate that tan should be tried whenever cosine or sine are, or you can pass a specific generator: >>> trigsimp_groebner(sin(x)/cos(x), hints=[tan]) tan(x) >>> trigsimp_groebner(sinh(x)/cosh(x), hints=[tanh(x)]) tanh(x) Finally, you can use the iterable form to suggest that angle sum formulae should be tried: >>> ex = (tan(x) + tan(y))/(1 - tan(x)tan(y)) >>> trigsimp_groebner(ex, hints=[(tan, x, y)]) tan(x + y) """ # TODO # - preprocess by replacing everything by funcs we can handle # - optionally use cot instead of tan # - more intelligent hinting. # For example, if the ideal is small, and we have sin(x), sin(y), # add sin(x + y) automatically... ? # - algebraic numbers ... # - expressions of lowest degree are not distinguished properly # e.g. 1 - sin(x)*2 # - we could try to order the generators intelligently, so as to influence # which monomials appear in the quotient basis # THEORY # ------ # Ratsimpmodprime above can be used to "simplify" a rational function # modulo a prime ideal. "Simplify" mainly means finding an equivalent # expression of lower total degree. # # We intend to use this to simplify trigonometric functions. To do that, # we need to decide (a) which ring to use, and (b) modulo which ideal to # simplify. In practice, (a) means settling on a list of "generators" # a, b, c, ..., such that the fraction we want to simplify is a rational # function in a, b, c, ..., with coefficients in ZZ (integers). # (2) means that we have to decide what relations to impose on the # generators. There are two practical problems: # (1) The ideal has to be prime* (a technical term). # (2) The relations have to be polynomials in the generators. # # We typically have two kinds of generators: # - trigonometric expressions, like sin(x), cos(5x), etc # - "everything else", like gamma(x), pi, etc. # # Since this function is trigsimp, we will concentrate on what to do with # trigonometric expressions. We can also simplify hyperbolic expressions, # but the extensions should be clear. # # One crucial point is that all other* generators really should behave # like indeterminates. In particular if (say) "I" is one of them, then # in fact I2 + 1 = 0 and we may and will compute non-sensical # expressions. However, we can work with a dummy and add the relation # I2 + 1 = 0 to our ideal, then substitute back in the end. # # Now regarding trigonometric generators. We split them into groups, # according to the argument of the trigonometric functions. We want to # organise this in such a way that most trigonometric identities apply in # the same group. For example, given sin(x), cos(2x) and cos(y), we would # group as [sin(x), cos(2x)] and [cos(y)]. # # Our prime ideal will be built in three steps: # (1) For each group, compute a "geometrically prime" ideal of relations. # Geometrically prime means that it generates a prime ideal in # CC[gens], not just ZZ[gens]. # (2) Take the union of all the generators of the ideals for all groups. # By the geometric primality condition, this is still prime. # (3) Add further inter-group relations which preserve primality. # # Step (1) works as follows. We will isolate common factors in the # argument, so that all our generators are of the form sin(nx), cos(nx) # or tan(nx), with n an integer. Suppose first there are no tan terms. # The ideal [sin(x)2 + cos(x)2 - 1] is geometrically prime, since # X2 + Y2 - 1 is irreducible over CC. # Now, if we have a generator sin(nx), than we can, using trig identities, # express sin(nx) as a polynomial in sin(x) and cos(x). We can add this # relation to the ideal, preserving geometric primality, since the quotient # ring is unchanged. # Thus we have treated all sin and cos terms. # For tan(nx), we add a relation tan(nx)cos(nx) - sin(nx) = 0. # (This requires of course that we already have relations for cos(nx) and # sin(nx).) It is not obvious, but it seems that this preserves geometric # primality. # XXX A real proof would be nice. HELP! # Sketch that <S2 + C2 - 1, CT - S> is a prime ideal of # CC[S, C, T]: # - it suffices to show that the projective closure in CP3 is # irreducible # - using the half-angle substitutions, we can express sin(x), tan(x), # cos(x) as rational functions in tan(x/2) # - from this, we get a rational map from CP1 to our curve # - this is a morphism, hence the curve is prime # # Step (2) is trivial. # # Step (3) works by adding selected relations of the form # sin(x + y) - sin(x)cos(y) - sin(y)cos(x), etc. Geometric primality is # preserved by the same argument as before. def parse_hints(hints): """Split hints into (n, funcs, iterables, gens).""" n = 1 funcs, iterables, gens = [], [], [] for e in hints: if isinstance(e, (SYMPY_INTS, Integer)): n = e elif isinstance(e, FunctionClass): funcs.append(e) elif iterable(e): iterables.append((e[0], e[1:])) # XXX sin(x+2y)? # Note: we go through polys so e.g. # sin(-x) -> -sin(x) -> sin(x) gens.extend(parallel_poly_from_expr( [e[0](x) for x in e[1:]] + [e[0](Add(e[1:]))])[1].gens) else: gens.append(e) return n, funcs, iterables, gens def build_ideal(x, terms): """ Build generators for our ideal. Terms is an iterable with elements of the form (fn, coeff), indicating that we have a generator fn(coeffx). If any of the terms is trigonometric, sin(x) and cos(x) are guaranteed to appear in terms. Similarly for hyperbolic functions. For tan(nx), sin(nx) and cos(nx) are guaranteed. """ I = [] y = Dummy('y') for fn, coeff in terms: for c, s, t, rel in ( [cos, sin, tan, cos(x)2 + sin(x)2 - 1], [cosh, sinh, tanh, cosh(x)2 - sinh(x)2 - 1]): if coeff == 1 and fn in [c, s]: I.append(rel) elif fn == t: I.append(t(coeffx)c(coeffx) - s(coeffx)) elif fn in [c, s]: cn = fn(coeffy).expand(trig=True).subs(y, x) I.append(fn(coeffx) - cn) return list(set(I)) def analyse_gens(gens, hints): """ Analyse the generators ``gens``, using the hints ``hints``. The meaning of ``hints`` is described in the main docstring. Return a new list of generators, and also the ideal we should work with. """ # First parse the hints n, funcs, iterables, extragens = parse_hints(hints) debug('n=%s' % n, 'funcs:', funcs, 'iterables:', iterables, 'extragens:', extragens) # We just add the extragens to gens and analyse them as before gens = list(gens) gens.extend(extragens) # remove duplicates funcs = list(set(funcs)) iterables = list(set(iterables)) gens = list(set(gens)) # all the functions we can do anything with allfuncs = {sin, cos, tan, sinh, cosh, tanh} # sin(3x) -> ((3, x), sin) trigterms = [(g.args[0].as_coeff_mul(), g.func) for g in gens if g.func in allfuncs] # Our list of new generators - start with anything that we cannot # work with (i.e. is not a trigonometric term) freegens = [g for g in gens if g.func not in allfuncs] newgens = [] trigdict = {} for (coeff, var), fn in trigterms: trigdict.setdefault(var, []).append((coeff, fn)) res = [] # the ideal for key, val in trigdict.items(): # We have now assembeled a dictionary. Its keys are common # arguments in trigonometric expressions, and values are lists of # pairs (fn, coeff). x0, (fn, coeff) in trigdict means that we # need to deal with fn(coeffx0). We take the rational gcd of the # coeffs, call it ``gcd``. We then use x = x0/gcd as "base symbol", # all other arguments are integral multiples thereof. # We will build an ideal which works with sin(x), cos(x). # If hint tan is provided, also work with tan(x). Moreover, if # n > 1, also work with sin(kx) for k <= n, and similarly for cos # (and tan if the hint is provided). Finally, any generators which # the ideal does not work with but we need to accommodate (either # because it was in expr or because it was provided as a hint) # we also build into the ideal. # This selection process is expressed in the list ``terms``. # build_ideal then generates the actual relations in our ideal, # from this list. fns = [x[1] for x in val] val = [x[0] for x in val] gcd = reduce(igcd, val) terms = [(fn, v/gcd) for (fn, v) in zip(fns, val)] fs = set(funcs + fns) for c, s, t in ([cos, sin, tan], [cosh, sinh, tanh]): if any(x in fs for x in (c, s, t)): fs.add(c) fs.add(s) for fn in fs: for k in range(1, n + 1): terms.append((fn, k)) extra = [] for fn, v in terms: if fn == tan: extra.append((sin, v)) extra.append((cos, v)) if fn in [sin, cos] and tan in fs: extra.append((tan, v)) if fn == tanh: extra.append((sinh, v)) extra.append((cosh, v)) if fn in [sinh, cosh] and tanh in fs: extra.append((tanh, v)) terms.extend(extra) x = gcdMul(key) r = build_ideal(x, terms) res.extend(r) newgens.extend(set(fn(vx) for fn, v in terms)) # Add generators for compound expressions from iterables for fn, args in iterables: if fn == tan: # Tan expressions are recovered from sin and cos. iterables.extend([(sin, args), (cos, args)]) elif fn == tanh: # Tanh expressions are recovered from sihn and cosh. iterables.extend([(sinh, args), (cosh, args)]) else: dummys = symbols('d:%i' % len(args), cls=Dummy) expr = fn( Add(dummys)).expand(trig=True).subs(list(zip(dummys, args))) res.append(fn(Add(args)) - expr) if myI in gens: res.append(myI*2 + 1) freegens.remove(myI) newgens.append(myI) return res, freegens, newgens myI = Dummy('I') expr = expr.subs(S.ImaginaryUnit, myI) subs = [(myI, S.ImaginaryUnit)] num, denom = cancel(expr).as_numer_denom() try: (pnum, pdenom), opt = parallel_poly_from_expr([num, denom]) except PolificationFailed: return expr debug('initial gens:', opt.gens) ideal, freegens, gens = analyse_gens(opt.gens, hints) debug('ideal:', ideal) debug('new gens:', gens, " -- len", len(gens)) debug('free gens:', freegens, " -- len", len(gens)) # NOTE we force the domain to be ZZ to stop polys from injecting generators # (which is usually a sign of a bug in the way we build the ideal) if not gens: return expr G = groebner(ideal, order=order, gens=gens, domain=ZZ) debug('groebner basis:', list(G), " -- len", len(G)) # If our fraction is a polynomial in the free generators, simplify all # coefficients separately: from sympy.simplify.ratsimp import ratsimpmodprime if freegens and pdenom.has_only_gens(set(gens).intersection(pdenom.gens)): num = Poly(num, gens=gens+freegens).eject(gens) res = [] for monom, coeff in num.terms(): ourgens = set(parallel_poly_from_expr([coeff, denom])[1].gens) # We compute the transitive closure of all generators that can # be reached from our generators through relations in the ideal. changed = True while changed: changed = False for p in ideal: p = Poly(p) if not ourgens.issuperset(p.gens) and \ not p.has_only_gens(set(p.gens).difference(ourgens)): changed = True ourgens.update(p.exclude().gens) # NOTE preserve order! realgens = [x for x in gens if x in ourgens] # The generators of the ideal have now been (implicitly) split # into two groups: those involving ourgens and those that don't. # Since we took the transitive closure above, these two groups # live in subgrings generated by a disjoint set of variables. # Any sensible groebner basis algorithm will preserve this disjoint # structure (i.e. the elements of the groebner basis can be split # similarly), and and the two subsets of the groebner basis then # form groebner bases by themselves. (For the smaller generating # sets, of course.) ourG = [g.as_expr() for g in G.polys if g.has_only_gens(ourgens.intersection(g.gens))] res.append(Mul([a*b for a, b in zip(freegens, monom)]) \ ratsimpmodprime(coeff/denom, ourG, order=order, gens=realgens, quick=quick, domain=ZZ, polynomial=polynomial).subs(subs)) return Add(res) # NOTE The following is simpler and has less assumptions on the # groebner basis algorithm. If the above turns out to be broken, # use this. return Add([Mul([ab for a, b in zip(freegens, monom)]) \ ratsimpmodprime(coeff/denom, list(G), order=order, gens=gens, quick=quick, domain=ZZ) for monom, coeff in num.terms()]) else: return ratsimpmodprime( expr, list(G), order=order, gens=freegens+gens, quick=quick, domain=ZZ, polynomial=polynomial).subs(subs) _trigs = (TrigonometricFunction, HyperbolicFunction) def trigsimp(expr, *opts): """ reduces expression by using known trig identities Notes ===== method: - Determine the method to use. Valid choices are 'matching' (default), 'groebner', 'combined', and 'fu'. If 'matching', simplify the expression recursively by targeting common patterns. If 'groebner', apply an experimental groebner basis algorithm. In this case further options are forwarded to ``trigsimp_groebner``, please refer to its docstring. If 'combined', first run the groebner basis algorithm with small default parameters, then run the 'matching' algorithm. 'fu' runs the collection of trigonometric transformations described by Fu, et al. (see the `fu` docstring). Examples ======== >>> from sympy import trigsimp, sin, cos, log >>> from sympy.abc import x, y >>> e = 2sin(x)*2 + 2cos(x)*2 >>> trigsimp(e) 2 Simplification occurs wherever trigonometric functions are located. >>> trigsimp(log(e)) log(2) Using `method="groebner"` (or `"combined"`) might lead to greater simplification. The old trigsimp routine can be accessed as with method 'old'. >>> from sympy import coth, tanh >>> t = 3tanh(x)7 - 2/coth(x)7 >>> trigsimp(t, method='old') == t True >>> trigsimp(t) tanh(x)7 """ from sympy.simplify.fu import fu expr = sympify(expr) try: return expr._eval_trigsimp(opts) except AttributeError: pass old = opts.pop('old', False) if not old: opts.pop('deep', None) opts.pop('recursive', None) method = opts.pop('method', 'matching') else: method = 'old' def groebnersimp(ex, opts): def traverse(e): if e.is_Atom: return e args = [traverse(x) for x in e.args] if e.is_Function or e.is_Pow: args = [trigsimp_groebner(x, opts) for x in args] return e.func(args) new = traverse(ex) if not isinstance(new, Expr): return new return trigsimp_groebner(new, opts) trigsimpfunc = { 'fu': (lambda x: fu(x, opts)), 'matching': (lambda x: futrig(x)), 'groebner': (lambda x: groebnersimp(x, opts)), 'combined': (lambda x: futrig(groebnersimp(x, polynomial=True, hints=[2, tan]))), 'old': lambda x: trigsimp_old(x, opts), }[method] return trigsimpfunc(expr) def exptrigsimp(expr): """ Simplifies exponential / trigonometric / hyperbolic functions. Examples ======== >>> from sympy import exptrigsimp, exp, cosh, sinh >>> from sympy.abc import z >>> exptrigsimp(exp(z) + exp(-z)) 2cosh(z) >>> exptrigsimp(cosh(z) - sinh(z)) exp(-z) """ from sympy.simplify.fu import hyper_as_trig, TR2i from sympy.simplify.simplify import bottom_up def exp_trig(e): # select the better of e, and e rewritten in terms of exp or trig # functions choices = [e] if e.has(_trigs): choices.append(e.rewrite(exp)) choices.append(e.rewrite(cos)) return min(choices, key=count_ops) newexpr = bottom_up(expr, exp_trig) def f(rv): if not rv.is_Mul: return rv commutative_part, noncommutative_part = rv.args_cnc() # Since as_powers_dict loses order information, # if there is more than one noncommutative factor, # it should only be used to simplify the commutative part. if (len(noncommutative_part) > 1): return f(Mul(commutative_part))Mul(noncommutative_part) rvd = rv.as_powers_dict() newd = rvd.copy() def signlog(expr, sign=1): if expr is S.Exp1: return sign, 1 elif isinstance(expr, exp): return sign, expr.args[0] elif sign == 1: return signlog(-expr, sign=-1) else: return None, None ee = rvd[S.Exp1] for k in rvd: if k.is_Add and len(k.args) == 2: # k == c(1 + signEx) c = k.args[0] sign, x = signlog(k.args[1]/c) if not x: continue m = rvd[k] newd[k] -= m if ee == -xm/2: # sinh and cosh newd[S.Exp1] -= ee ee = 0 if sign == 1: newd[2ccosh(x/2)] += m else: newd[-2csinh(x/2)] += m elif newd[1 - signS.Exp1x] == -m: # tanh del newd[1 - signS.Exp1*x] if sign == 1: newd[-c/tanh(x/2)] += m else: newd[-ctanh(x/2)] += m else: newd[1 + signS.Exp1x] += m newd[c] += m return Mul([knewd[k] for k in newd]) newexpr = bottom_up(newexpr, f) # sin/cos and sinh/cosh ratios to tan and tanh, respectively if newexpr.has(HyperbolicFunction): e, f = hyper_as_trig(newexpr) newexpr = f(TR2i(e)) if newexpr.has(TrigonometricFunction): newexpr = TR2i(newexpr) # can we ever generate an I where there was none previously? if not (newexpr.has(I) and not expr.has(I)): expr = newexpr return expr #-------------------- the old trigsimp routines --------------------- def trigsimp_old(expr, opts): """ reduces expression by using known trig identities Notes ===== deep: - Apply trigsimp inside all objects with arguments recursive: - Use common subexpression elimination (cse()) and apply trigsimp recursively (this is quite expensive if the expression is large) method: - Determine the method to use. Valid choices are 'matching' (default), 'groebner', 'combined', 'fu' and 'futrig'. If 'matching', simplify the expression recursively by pattern matching. If 'groebner', apply an experimental groebner basis algorithm. In this case further options are forwarded to ``trigsimp_groebner``, please refer to its docstring. If 'combined', first run the groebner basis algorithm with small default parameters, then run the 'matching' algorithm. 'fu' runs the collection of trigonometric transformations described by Fu, et al. (see the `fu` docstring) while `futrig` runs a subset of Fu-transforms that mimic the behavior of `trigsimp`. compare: - show input and output from `trigsimp` and `futrig` when different, but returns the `trigsimp` value. Examples ======== >>> from sympy import trigsimp, sin, cos, log, cosh, sinh, tan, cot >>> from sympy.abc import x, y >>> e = 2sin(x)2 + 2cos(x)*2 >>> trigsimp(e, old=True) 2 >>> trigsimp(log(e), old=True) log(2sin(x)*2 + 2cos(x)2) >>> trigsimp(log(e), deep=True, old=True) log(2) Using `method="groebner"` (or `"combined"`) can sometimes lead to a lot more simplification: >>> e = (-sin(x) + 1)/cos(x) + cos(x)/(-sin(x) + 1) >>> trigsimp(e, old=True) (-sin(x) + 1)/cos(x) + cos(x)/(-sin(x) + 1) >>> trigsimp(e, method="groebner", old=True) 2/cos(x) >>> trigsimp(1/cot(x)2, compare=True, old=True) futrig: tan(x)2 cot(x)(-2) """ old = expr first = opts.pop('first', True) if first: if not expr.has(_trigs): return expr trigsyms = set().union([t.free_symbols for t in expr.atoms(_trigs)]) if len(trigsyms) > 1: from sympy.simplify.simplify import separatevars d = separatevars(expr) if d.is_Mul: d = separatevars(d, dict=True) or d if isinstance(d, dict): expr = 1 for k, v in d.items(): # remove hollow factoring was = v v = expand_mul(v) opts['first'] = False vnew = trigsimp(v, opts) if vnew == v: vnew = was expr = vnew old = expr else: if d.is_Add: for s in trigsyms: r, e = expr.as_independent(s) if r: opts['first'] = False expr = r + trigsimp(e, opts) if not expr.is_Add: break old = expr recursive = opts.pop('recursive', False) deep = opts.pop('deep', False) method = opts.pop('method', 'matching') def groebnersimp(ex, deep, opts): def traverse(e): if e.is_Atom: return e args = [traverse(x) for x in e.args] if e.is_Function or e.is_Pow: args = [trigsimp_groebner(x, *opts) for x in args] return e.func(args) if deep: ex = traverse(ex) return trigsimp_groebner(ex, opts) trigsimpfunc = { 'matching': (lambda x, d: _trigsimp(x, d)), 'groebner': (lambda x, d: groebnersimp(x, d, opts)), 'combined': (lambda x, d: _trigsimp(groebnersimp(x, d, polynomial=True, hints=[2, tan]), d)) }[method] if recursive: w, g = cse(expr) g = trigsimpfunc(g[0], deep) for sub in reversed(w): g = g.subs(sub[0], sub[1]) g = trigsimpfunc(g, deep) result = g else: result = trigsimpfunc(expr, deep) if opts.get('compare', False): f = futrig(old) if f != result: print('\tfutrig:', f) return result def _dotrig(a, b): """Helper to tell whether ``a`` and ``b`` have the same sorts of symbols in them -- no need to test hyperbolic patterns against expressions that have no hyperbolics in them.""" return a.func == b.func and ( a.has(TrigonometricFunction) and b.has(TrigonometricFunction) or a.has(HyperbolicFunction) and b.has(HyperbolicFunction)) _trigpat = None def _trigpats(): global _trigpat a, b, c = symbols('a b c', cls=Wild) d = Wild('d', commutative=False) # for the simplifications like sinh/cosh -> tanh: # DO NOT REORDER THE FIRST 14 since these are assumed to be in this # order in _match_div_rewrite. matchers_division = ( (asin(b)c/cos(b)c, atan(b)*c, sin(b), cos(b)), (atan(b)*ccos(b)*c, asin(b)*c, sin(b), cos(b)), (acot(b)*csin(b)*c, acos(b)*c, sin(b), cos(b)), (atan(b)c/sin(b)c, a/cos(b)*c, sin(b), cos(b)), (acot(b)c/cos(b)c, a/sin(b)*c, sin(b), cos(b)), (acot(b)*ctan(b)*c, a, sin(b), cos(b)), (a(cos(b) + 1)*c(cos(b) - 1)*c, a(-sin(b)2)c, cos(b) + 1, cos(b) - 1), (a(sin(b) + 1)c(sin(b) - 1)*c, a(-cos(b)2)c, sin(b) + 1, sin(b) - 1), (asinh(b)c/cosh(b)c, atanh(b)*c, S.One, S.One), (atanh(b)*ccosh(b)*c, asinh(b)*c, S.One, S.One), (acoth(b)*csinh(b)*c, acosh(b)*c, S.One, S.One), (atanh(b)c/sinh(b)c, a/cosh(b)*c, S.One, S.One), (acoth(b)c/cosh(b)c, a/sinh(b)*c, S.One, S.One), (acoth(b)*ctanh(b)*c, a, S.One, S.One), (c(tanh(a) + tanh(b))/(1 + tanh(a)tanh(b)), tanh(a + b)c, S.One, S.One), ) matchers_add = ( (csin(a)cos(b) + ccos(a)sin(b) + d, sin(a + b)c + d), (ccos(a)cos(b) - csin(a)sin(b) + d, cos(a + b)c + d), (csin(a)cos(b) - ccos(a)sin(b) + d, sin(a - b)c + d), (ccos(a)cos(b) + csin(a)sin(b) + d, cos(a - b)c + d), (csinh(a)cosh(b) + csinh(b)cosh(a) + d, sinh(a + b)c + d), (ccosh(a)cosh(b) + csinh(a)sinh(b) + d, cosh(a + b)c + d), ) # for cos(x)2 + sin(x)2 -> 1 matchers_identity = ( (asin(b)2, a - acos(b)*2), (atan(b)*2, a(1/cos(b))*2 - a), (acot(b)*2, a(1/sin(b))*2 - a), (asin(b + c), a(sin(b)cos(c) + sin(c)cos(b))), (acos(b + c), a(cos(b)cos(c) - sin(b)sin(c))), (atan(b + c), a((tan(b) + tan(c))/(1 - tan(b)tan(c)))), (asinh(b)2, acosh(b)*2 - a), (atanh(b)*2, a - a(1/cosh(b))*2), (acoth(b)*2, a + a(1/sinh(b))*2), (asinh(b + c), a(sinh(b)cosh(c) + sinh(c)cosh(b))), (acosh(b + c), a(cosh(b)cosh(c) + sinh(b)sinh(c))), (atanh(b + c), a((tanh(b) + tanh(c))/(1 + tanh(b)tanh(c)))), ) # Reduce any lingering artifacts, such as sin(x)2 changing # to 1-cos(x)2 when sin(x)*2 was "simpler" artifacts = ( (a - acos(b)*2 + c, asin(b)*2 + c, cos), (a - a(1/cos(b))*2 + c, -atan(b)*2 + c, cos), (a - a(1/sin(b))*2 + c, -acot(b)*2 + c, sin), (a - acosh(b)*2 + c, -asinh(b)*2 + c, cosh), (a - a(1/cosh(b))*2 + c, atanh(b)*2 + c, cosh), (a + a(1/sinh(b))*2 + c, acoth(b)*2 + c, sinh), # same as above but with noncommutative prefactor (ad - adcos(b)*2 + c, adsin(b)2 + c, cos), (ad - ad(1/cos(b))*2 + c, -adtan(b)2 + c, cos), (ad - ad(1/sin(b))*2 + c, -adcot(b)2 + c, sin), (ad - adcosh(b)*2 + c, -adsinh(b)2 + c, cosh), (ad - ad(1/cosh(b))*2 + c, adtanh(b)2 + c, cosh), (ad + ad(1/sinh(b))*2 + c, adcoth(b)2 + c, sinh), ) _trigpat = (a, b, c, d, matchers_division, matchers_add, matchers_identity, artifacts) return _trigpat def _replace_mul_fpowxgpow(expr, f, g, rexp, h, rexph): """Helper for _match_div_rewrite. Replace f(b_)c_g(b_)(rexp(c_)) with h(b)rexph(c) if f(b_) and g(b_) are both positive or if c_ is an integer. """ # assert expr.is_Mul and expr.is_commutative and f != g fargs = defaultdict(int) gargs = defaultdict(int) args = [] for x in expr.args: if x.is_Pow or x.func in (f, g): b, e = x.as_base_exp() if b.is_positive or e.is_integer: if b.func == f: fargs[b.args[0]] += e continue elif b.func == g: gargs[b.args[0]] += e continue args.append(x) common = set(fargs) & set(gargs) hit = False while common: key = common.pop() fe = fargs.pop(key) ge = gargs.pop(key) if fe == rexp(ge): args.append(h(key)rexph(fe)) hit = True else: fargs[key] = fe gargs[key] = ge if not hit: return expr while fargs: key, e = fargs.popitem() args.append(f(key)e) while gargs: key, e = gargs.popitem() args.append(g(key)*e) return Mul(args) _idn = lambda x: x _midn = lambda x: -x _one = lambda x: S.One def _match_div_rewrite(expr, i): """helper for __trigsimp""" if i == 0: expr = _replace_mul_fpowxgpow(expr, sin, cos, _midn, tan, _idn) elif i == 1: expr = _replace_mul_fpowxgpow(expr, tan, cos, _idn, sin, _idn) elif i == 2: expr = _replace_mul_fpowxgpow(expr, cot, sin, _idn, cos, _idn) elif i == 3: expr = _replace_mul_fpowxgpow(expr, tan, sin, _midn, cos, _midn) elif i == 4: expr = _replace_mul_fpowxgpow(expr, cot, cos, _midn, sin, _midn) elif i == 5: expr = _replace_mul_fpowxgpow(expr, cot, tan, _idn, _one, _idn) # i in (6, 7) is skipped elif i == 8: expr = _replace_mul_fpowxgpow(expr, sinh, cosh, _midn, tanh, _idn) elif i == 9: expr = _replace_mul_fpowxgpow(expr, tanh, cosh, _idn, sinh, _idn) elif i == 10: expr = _replace_mul_fpowxgpow(expr, coth, sinh, _idn, cosh, _idn) elif i == 11: expr = _replace_mul_fpowxgpow(expr, tanh, sinh, _midn, cosh, _midn) elif i == 12: expr = _replace_mul_fpowxgpow(expr, coth, cosh, _midn, sinh, _midn) elif i == 13: expr = _replace_mul_fpowxgpow(expr, coth, tanh, _idn, _one, _idn) else: return None return expr def _trigsimp(expr, deep=False): # protect the cache from non-trig patterns; we only allow # trig patterns to enter the cache if expr.has(_trigs): return __trigsimp(expr, deep) return expr @cacheit def __trigsimp(expr, deep=False): """recursive helper for trigsimp""" from sympy.simplify.fu import TR10i if _trigpat is None: _trigpats() a, b, c, d, matchers_division, matchers_add, \ matchers_identity, artifacts = _trigpat if expr.is_Mul: # do some simplifications like sin/cos -> tan: if not expr.is_commutative: com, nc = expr.args_cnc() expr = _trigsimp(Mul._from_args(com), deep)Mul._from_args(nc) else: for i, (pattern, simp, ok1, ok2) in enumerate(matchers_division): if not _dotrig(expr, pattern): continue newexpr = _match_div_rewrite(expr, i) if newexpr is not None: if newexpr != expr: expr = newexpr break else: continue # use SymPy matching instead res = expr.match(pattern) if res and res.get(c, 0): if not res[c].is_integer: ok = ok1.subs(res) if not ok.is_positive: continue ok = ok2.subs(res) if not ok.is_positive: continue # if "a" contains any of trig or hyperbolic funcs with # argument "b" then skip the simplification if any(w.args[0] == res[b] for w in res[a].atoms( TrigonometricFunction, HyperbolicFunction)): continue # simplify and finish: expr = simp.subs(res) break # process below if expr.is_Add: args = [] for term in expr.args: if not term.is_commutative: com, nc = term.args_cnc() nc = Mul._from_args(nc) term = Mul._from_args(com) else: nc = S.One term = _trigsimp(term, deep) for pattern, result in matchers_identity: res = term.match(pattern) if res is not None: term = result.subs(res) break args.append(termnc) if args != expr.args: expr = Add(args) expr = min(expr, expand(expr), key=count_ops) if expr.is_Add: for pattern, result in matchers_add: if not _dotrig(expr, pattern): continue expr = TR10i(expr) if expr.has(HyperbolicFunction): res = expr.match(pattern) # if "d" contains any trig or hyperbolic funcs with # argument "a" or "b" then skip the simplification; # this isn't perfect -- see tests if res is None or not (a in res and b in res) or any( w.args[0] in (res[a], res[b]) for w in res[d].atoms( TrigonometricFunction, HyperbolicFunction)): continue expr = result.subs(res) break # Reduce any lingering artifacts, such as sin(x)2 changing # to 1 - cos(x)2 when sin(x)2 was "simpler" for pattern, result, ex in artifacts: if not _dotrig(expr, pattern): continue # Substitute a new wild that excludes some function(s) # to help influence a better match. This is because # sometimes, for example, 'a' would match sec(x)2 a_t = Wild('a', exclude=[ex]) pattern = pattern.subs(a, a_t) result = result.subs(a, a_t) m = expr.match(pattern) was = None while m and was != expr: was = expr if m[a_t] == 0 or \ -m[a_t] in m[c].args or m[a_t] + m[c] == 0: break if d in m and m[a_t]m[d] + m[c] == 0: break expr = result.subs(m) m = expr.match(pattern) m.setdefault(c, S.Zero) elif expr.is_Mul or expr.is_Pow or deep and expr.args: expr = expr.func([_trigsimp(a, deep) for a in expr.args]) try: if not expr.has(_trigs): raise TypeError e = expr.atoms(exp) new = expr.rewrite(exp, deep=deep) if new == e: raise TypeError fnew = factor(new) if fnew != new: new = sorted([new, factor(new)], key=count_ops)[0] # if all exp that were introduced disappeared then accept it if not (new.atoms(exp) - e): expr = new except TypeError: pass return expr #------------------- end of old trigsimp routines -------------------- def futrig(e, kwargs): """Return simplified ``e`` using Fu-like transformations. This is not the "Fu" algorithm. This is called by default from ``trigsimp``. By default, hyperbolics subexpressions will be simplified, but this can be disabled by setting ``hyper=False``. Examples ======== >>> from sympy import trigsimp, tan, sinh, tanh >>> from sympy.simplify.trigsimp import futrig >>> from sympy.abc import x >>> trigsimp(1/tan(x)2) tan(x)(-2) >>> futrig(sinh(x)/tanh(x)) cosh(x) """ from sympy.simplify.fu import hyper_as_trig from sympy.simplify.simplify import bottom_up e = sympify(e) if not isinstance(e, Basic): return e if not e.args: return e old = e e = bottom_up(e, lambda x: _futrig(x, kwargs)) if kwargs.pop('hyper', True) and e.has(HyperbolicFunction): e, f = hyper_as_trig(e) e = f(_futrig(e)) if e != old and e.is_Mul and e.args[0].is_Rational: # redistribute leading coeff on 2-arg Add e = Mul(e.as_coeff_Mul()) return e def _futrig(e, *kwargs): """Helper for futrig.""" from sympy.simplify.fu import ( TR1, TR2, TR3, TR2i, TR10, L, TR10i, TR8, TR6, TR15, TR16, TR111, TR5, TRmorrie, TR11, TR14, TR22, TR12) from sympy.core.compatibility import _nodes if not e.has(TrigonometricFunction): return e if e.is_Mul: coeff, e = e.as_independent(TrigonometricFunction) else: coeff = S.One Lops = lambda x: (L(x), x.count_ops(), _nodes(x), len(x.args), x.is_Add) trigs = lambda x: x.has(TrigonometricFunction) tree = [identity, ( TR3, # canonical angles TR1, # sec-csc -> cos-sin TR12, # expand tan of sum lambda x: _eapply(factor, x, trigs), TR2, # tan-cot -> sin-cos [identity, lambda x: _eapply(_mexpand, x, trigs)], TR2i, # sin-cos ratio -> tan lambda x: _eapply(lambda i: factor(i.normal()), x, trigs), TR14, # factored identities TR5, # sin-pow -> cos_pow TR10, # sin-cos of sums -> sin-cos prod TR11, TR6, # reduce double angles and rewrite cos pows lambda x: _eapply(factor, x, trigs), TR14, # factored powers of identities [identity, lambda x: _eapply(_mexpand, x, trigs)], TR10i, # sin-cos products > sin-cos of sums TRmorrie, [identity, TR8], # sin-cos products -> sin-cos of sums [identity, lambda x: TR2i(TR2(x))], # tan -> sin-cos -> tan [ lambda x: _eapply(expand_mul, TR5(x), trigs), lambda x: _eapply( expand_mul, TR15(x), trigs)], # pos/neg powers of sin [ lambda x: _eapply(expand_mul, TR6(x), trigs), lambda x: _eapply( expand_mul, TR16(x), trigs)], # pos/neg powers of cos TR111, # tan, sin, cos to neg power -> cot, csc, sec [identity, TR2i], # sin-cos ratio to tan [identity, lambda x: _eapply( expand_mul, TR22(x), trigs)], # tan-cot to sec-csc TR1, TR2, TR2i, [identity, lambda x: _eapply( factor_terms, TR12(x), trigs)], # expand tan of sum )] e = greedy(tree, objective=Lops)(e) return coeffe def _is_Expr(e): """_eapply helper to tell whether ``e`` and all its args are Exprs.""" from sympy import Derivative if isinstance(e, Derivative): return _is_Expr(e.expr) if not isinstance(e, Expr): return False return all(_is_Expr(i) for i in e.args) def _eapply(func, e, cond=None): """Apply ``func`` to ``e`` if all args are Exprs else only apply it to those args that are Exprs.""" if not isinstance(e, Expr): return e if _is_Expr(e) or not e.args: return func(e) return e.func(*[ _eapply(func, ei) if (cond is None or cond(ei)) else ei for ei in e.args])
6d40b9971893432048058213f50e5f1d6e0d2b150ed7644d4a2b99338198d634	""" Tools for doing common subexpression elimination. """ from __future__ import print_function, division from sympy.core import Basic, Mul, Add, Pow, sympify, Symbol from sympy.core.compatibility import iterable, range from sympy.core.containers import Tuple, OrderedSet from sympy.core.exprtools import factor_terms from sympy.core.function import _coeff_isneg from sympy.core.singleton import S from sympy.utilities.iterables import numbered_symbols, sift, \ topological_sort, ordered from . import cse_opts # (preprocessor, postprocessor) pairs which are commonly useful. They should # each take a sympy expression and return a possibly transformed expression. # When used in the function ``cse()``, the target expressions will be transformed # by each of the preprocessor functions in order. After the common # subexpressions are eliminated, each resulting expression will have the # postprocessor functions transform them in reverse order in order to undo the # transformation if necessary. This allows the algorithm to operate on # a representation of the expressions that allows for more optimization # opportunities. # ``None`` can be used to specify no transformation for either the preprocessor or # postprocessor. basic_optimizations = [(cse_opts.sub_pre, cse_opts.sub_post), (factor_terms, None)] # sometimes we want the output in a different format; non-trivial # transformations can be put here for users # =============================================================== def reps_toposort(r): """Sort replacements `r` so (k1, v1) appears before (k2, v2) if k2 is in v1's free symbols. This orders items in the way that cse returns its results (hence, in order to use the replacements in a substitution option it would make sense to reverse the order). Examples ======== >>> from sympy.simplify.cse_main import reps_toposort >>> from sympy.abc import x, y >>> from sympy import Eq >>> for l, r in reps_toposort([(x, y + 1), (y, 2)]): ... print(Eq(l, r)) ... Eq(y, 2) Eq(x, y + 1) """ r = sympify(r) E = [] for c1, (k1, v1) in enumerate(r): for c2, (k2, v2) in enumerate(r): if k1 in v2.free_symbols: E.append((c1, c2)) return [r[i] for i in topological_sort((range(len(r)), E))] def cse_separate(r, e): """Move expressions that are in the form (symbol, expr) out of the expressions and sort them into the replacements using the reps_toposort. Examples ======== >>> from sympy.simplify.cse_main import cse_separate >>> from sympy.abc import x, y, z >>> from sympy import cos, exp, cse, Eq, symbols >>> x0, x1 = symbols('x:2') >>> eq = (x + 1 + exp((x + 1)/(y + 1)) + cos(y + 1)) >>> cse([eq, Eq(x, z + 1), z - 2], postprocess=cse_separate) in [ ... [[(x0, y + 1), (x, z + 1), (x1, x + 1)], ... [x1 + exp(x1/x0) + cos(x0), z - 2]], ... [[(x1, y + 1), (x, z + 1), (x0, x + 1)], ... [x0 + exp(x0/x1) + cos(x1), z - 2]]] ... True """ d = sift(e, lambda w: w.is_Equality and w.lhs.is_Symbol) r = r + [w.args for w in d[True]] e = d[False] return [reps_toposort(r), e] # ====end of cse postprocess idioms=========================== def preprocess_for_cse(expr, optimizations): """ Preprocess an expression to optimize for common subexpression elimination. Parameters ========== expr : sympy expression The target expression to optimize. optimizations : list of (callable, callable) pairs The (preprocessor, postprocessor) pairs. Returns ======= expr : sympy expression The transformed expression. """ for pre, post in optimizations: if pre is not None: expr = pre(expr) return expr def postprocess_for_cse(expr, optimizations): """ Postprocess an expression after common subexpression elimination to return the expression to canonical sympy form. Parameters ========== expr : sympy expression The target expression to transform. optimizations : list of (callable, callable) pairs, optional The (preprocessor, postprocessor) pairs. The postprocessors will be applied in reversed order to undo the effects of the preprocessors correctly. Returns ======= expr : sympy expression The transformed expression. """ for pre, post in reversed(optimizations): if post is not None: expr = post(expr) return expr class FuncArgTracker(object): """ A class which manages a mapping from functions to arguments and an inverse mapping from arguments to functions. """ def __init__(self, funcs): # To minimize the number of symbolic comparisons, all function arguments # get assigned a value number. self.value_numbers = {} self.value_number_to_value = [] # Both of these maps use integer indices for arguments / functions. self.arg_to_funcset = [] self.func_to_argset = [] for func_i, func in enumerate(funcs): func_argset = OrderedSet() for func_arg in func.args: arg_number = self.get_or_add_value_number(func_arg) func_argset.add(arg_number) self.arg_to_funcset[arg_number].add(func_i) self.func_to_argset.append(func_argset) def get_args_in_value_order(self, argset): """ Return the list of arguments in sorted order according to their value numbers. """ return [self.value_number_to_value[argn] for argn in sorted(argset)] def get_or_add_value_number(self, value): """ Return the value number for the given argument. """ nvalues = len(self.value_numbers) value_number = self.value_numbers.setdefault(value, nvalues) if value_number == nvalues: self.value_number_to_value.append(value) self.arg_to_funcset.append(OrderedSet()) return value_number def stop_arg_tracking(self, func_i): """ Remove the function func_i from the argument to function mapping. """ for arg in self.func_to_argset[func_i]: self.arg_to_funcset[arg].remove(func_i) def get_common_arg_candidates(self, argset, min_func_i=0): """Return a dict whose keys are function numbers. The entries of the dict are the number of arguments said function has in common with `argset`. Entries have at least 2 items in common. All keys have value at least `min_func_i`. """ from collections import defaultdict count_map = defaultdict(lambda: 0) funcsets = [self.arg_to_funcset[arg] for arg in argset] # As an optimization below, we handle the largest funcset separately from # the others. largest_funcset = max(funcsets, key=len) for funcset in funcsets: if largest_funcset is funcset: continue for func_i in funcset: if func_i >= min_func_i: count_map[func_i] += 1 # We pick the smaller of the two containers (count_map, largest_funcset) # to iterate over to reduce the number of iterations needed. (smaller_funcs_container, larger_funcs_container) = sorted( [largest_funcset, count_map], key=len) for func_i in smaller_funcs_container: # Not already in count_map? It can't possibly be in the output, so # skip it. if count_map[func_i] < 1: continue if func_i in larger_funcs_container: count_map[func_i] += 1 return dict((k, v) for k, v in count_map.items() if v >= 2) def get_subset_candidates(self, argset, restrict_to_funcset=None): """ Return a set of functions each of which whose argument list contains ``argset``, optionally filtered only to contain functions in ``restrict_to_funcset``. """ iarg = iter(argset) indices = OrderedSet( fi for fi in self.arg_to_funcset[next(iarg)]) if restrict_to_funcset is not None: indices &= restrict_to_funcset for arg in iarg: indices &= self.arg_to_funcset[arg] return indices def update_func_argset(self, func_i, new_argset): """ Update a function with a new set of arguments. """ new_args = OrderedSet(new_argset) old_args = self.func_to_argset[func_i] for deleted_arg in old_args - new_args: self.arg_to_funcset[deleted_arg].remove(func_i) for added_arg in new_args - old_args: self.arg_to_funcset[added_arg].add(func_i) self.func_to_argset[func_i].clear() self.func_to_argset[func_i].update(new_args) class Unevaluated(object): def __init__(self, func, args): self.func = func self.args = args def __str__(self): return "Uneval<{}>({})".format( self.func, ", ".join(str(a) for a in self.args)) def as_unevaluated_basic(self): return self.func(self.args, evaluate=False) @property def free_symbols(self): return set().union([a.free_symbols for a in self.args]) __repr__ = __str__ def match_common_args(func_class, funcs, opt_subs): """ Recognize and extract common subexpressions of function arguments within a set of function calls. For instance, for the following function calls:: x + z + y sin(x + y) this will extract a common subexpression of `x + y`:: w = x + y w + z sin(w) The function we work with is assumed to be associative and commutative. Parameters ========== func_class: class The function class (e.g. Add, Mul) funcs: list of functions A list of function calls opt_subs: dict A dictionary of substitutions which this function may update """ # Sort to ensure that whole-function subexpressions come before the items # that use them. funcs = sorted(funcs, key=lambda f: len(f.args)) arg_tracker = FuncArgTracker(funcs) changed = OrderedSet() for i in range(len(funcs)): common_arg_candidates_counts = arg_tracker.get_common_arg_candidates( arg_tracker.func_to_argset[i], min_func_i=i + 1) # Sort the candidates in order of match size. # This makes us try combining smaller matches first. common_arg_candidates = OrderedSet(sorted( common_arg_candidates_counts.keys(), key=lambda k: (common_arg_candidates_counts[k], k))) while common_arg_candidates: j = common_arg_candidates.pop(last=False) com_args = arg_tracker.func_to_argset[i].intersection( arg_tracker.func_to_argset[j]) if len(com_args) <= 1: # This may happen if a set of common arguments was already # combined in a previous iteration. continue # For all sets, replace the common symbols by the function # over them, to allow recursive matches. diff_i = arg_tracker.func_to_argset[i].difference(com_args) if diff_i: # com_func needs to be unevaluated to allow for recursive matches. com_func = Unevaluated( func_class, arg_tracker.get_args_in_value_order(com_args)) com_func_number = arg_tracker.get_or_add_value_number(com_func) arg_tracker.update_func_argset(i, diff_i \| OrderedSet([com_func_number])) changed.add(i) else: # Treat the whole expression as a CSE. # # The reason this needs to be done is somewhat subtle. Within # tree_cse(), to_eliminate only contains expressions that are # seen more than once. The problem is unevaluated expressions # do not compare equal to the evaluated equivalent. So # tree_cse() won't mark funcs[i] as a CSE if we use an # unevaluated version. com_func = funcs[i] com_func_number = arg_tracker.get_or_add_value_number(funcs[i]) diff_j = arg_tracker.func_to_argset[j].difference(com_args) arg_tracker.update_func_argset(j, diff_j \| OrderedSet([com_func_number])) changed.add(j) for k in arg_tracker.get_subset_candidates( com_args, common_arg_candidates): diff_k = arg_tracker.func_to_argset[k].difference(com_args) arg_tracker.update_func_argset(k, diff_k \| OrderedSet([com_func_number])) changed.add(k) if i in changed: opt_subs[funcs[i]] = Unevaluated(func_class, arg_tracker.get_args_in_value_order(arg_tracker.func_to_argset[i])) arg_tracker.stop_arg_tracking(i) def opt_cse(exprs, order='canonical'): """Find optimization opportunities in Adds, Muls, Pows and negative coefficient Muls Parameters ========== exprs : list of sympy expressions The expressions to optimize. order : string, 'none' or 'canonical' The order by which Mul and Add arguments are processed. For large expressions where speed is a concern, use the setting order='none'. Returns ======= opt_subs : dictionary of expression substitutions The expression substitutions which can be useful to optimize CSE. Examples ======== >>> from sympy.simplify.cse_main import opt_cse >>> from sympy.abc import x >>> opt_subs = opt_cse([x-2]) >>> k, v = list(opt_subs.keys())[0], list(opt_subs.values())[0] >>> print((k, v.as_unevaluated_basic())) (x(-2), 1/(x*2)) """ from sympy.matrices.expressions import MatAdd, MatMul, MatPow opt_subs = dict() adds = OrderedSet() muls = OrderedSet() seen_subexp = set() def _find_opts(expr): if not isinstance(expr, (Basic, Unevaluated)): return if expr.is_Atom or expr.is_Order: return if iterable(expr): list(map(_find_opts, expr)) return if expr in seen_subexp: return expr seen_subexp.add(expr) list(map(_find_opts, expr.args)) if _coeff_isneg(expr): neg_expr = -expr if not neg_expr.is_Atom: opt_subs[expr] = Unevaluated(Mul, (S.NegativeOne, neg_expr)) seen_subexp.add(neg_expr) expr = neg_expr if isinstance(expr, (Mul, MatMul)): muls.add(expr) elif isinstance(expr, (Add, MatAdd)): adds.add(expr) elif isinstance(expr, (Pow, MatPow)): base, exp = expr.base, expr.exp if _coeff_isneg(exp): opt_subs[expr] = Unevaluated(Pow, (Pow(base, -exp), -1)) for e in exprs: if isinstance(e, (Basic, Unevaluated)): _find_opts(e) # split muls into commutative commutative_muls = OrderedSet() for m in muls: c, nc = m.args_cnc(cset=False) if c: c_mul = m.func(c) if nc: if c_mul == 1: new_obj = m.func(nc) else: new_obj = m.func(c_mul, m.func(nc), evaluate=False) opt_subs[m] = new_obj if len(c) > 1: commutative_muls.add(c_mul) match_common_args(Add, adds, opt_subs) match_common_args(Mul, commutative_muls, opt_subs) return opt_subs def tree_cse(exprs, symbols, opt_subs=None, order='canonical', ignore=()): """Perform raw CSE on expression tree, taking opt_subs into account. Parameters ========== exprs : list of sympy expressions The expressions to reduce. symbols : infinite iterator yielding unique Symbols The symbols used to label the common subexpressions which are pulled out. opt_subs : dictionary of expression substitutions The expressions to be substituted before any CSE action is performed. order : string, 'none' or 'canonical' The order by which Mul and Add arguments are processed. For large expressions where speed is a concern, use the setting order='none'. ignore : iterable of Symbols Substitutions containing any Symbol from ``ignore`` will be ignored. """ from sympy.matrices.expressions import MatrixExpr, MatrixSymbol, MatMul, MatAdd if opt_subs is None: opt_subs = dict() ## Find repeated sub-expressions to_eliminate = set() seen_subexp = set() excluded_symbols = set() def _find_repeated(expr): if not isinstance(expr, (Basic, Unevaluated)): return if isinstance(expr, Basic) and (expr.is_Atom or expr.is_Order): if expr.is_Symbol: excluded_symbols.add(expr) return if iterable(expr): args = expr else: if expr in seen_subexp: for ign in ignore: if ign in expr.free_symbols: break else: to_eliminate.add(expr) return seen_subexp.add(expr) if expr in opt_subs: expr = opt_subs[expr] args = expr.args list(map(_find_repeated, args)) for e in exprs: if isinstance(e, Basic): _find_repeated(e) ## Rebuild tree # Remove symbols from the generator that conflict with names in the expressions. symbols = (symbol for symbol in symbols if symbol not in excluded_symbols) replacements = [] subs = dict() def _rebuild(expr): if not isinstance(expr, (Basic, Unevaluated)): return expr if not expr.args: return expr if iterable(expr): new_args = [_rebuild(arg) for arg in expr] return expr.func(new_args) if expr in subs: return subs[expr] orig_expr = expr if expr in opt_subs: expr = opt_subs[expr] # If enabled, parse Muls and Adds arguments by order to ensure # replacement order independent from hashes if order != 'none': if isinstance(expr, (Mul, MatMul)): c, nc = expr.args_cnc() if c == [1]: args = nc else: args = list(ordered(c)) + nc elif isinstance(expr, (Add, MatAdd)): args = list(ordered(expr.args)) else: args = expr.args else: args = expr.args new_args = list(map(_rebuild, args)) if isinstance(expr, Unevaluated) or new_args != args: new_expr = expr.func(new_args) else: new_expr = expr if orig_expr in to_eliminate: try: sym = next(symbols) except StopIteration: raise ValueError("Symbols iterator ran out of symbols.") if isinstance(orig_expr, MatrixExpr): sym = MatrixSymbol(sym.name, orig_expr.rows, orig_expr.cols) subs[orig_expr] = sym replacements.append((sym, new_expr)) return sym else: return new_expr reduced_exprs = [] for e in exprs: if isinstance(e, Basic): reduced_e = _rebuild(e) else: reduced_e = e reduced_exprs.append(reduced_e) return replacements, reduced_exprs def cse(exprs, symbols=None, optimizations=None, postprocess=None, order='canonical', ignore=()): """ Perform common subexpression elimination on an expression. Parameters ========== exprs : list of sympy expressions, or a single sympy expression The expressions to reduce. symbols : infinite iterator yielding unique Symbols The symbols used to label the common subexpressions which are pulled out. The ``numbered_symbols`` generator is useful. The default is a stream of symbols of the form "x0", "x1", etc. This must be an infinite iterator. optimizations : list of (callable, callable) pairs The (preprocessor, postprocessor) pairs of external optimization functions. Optionally 'basic' can be passed for a set of predefined basic optimizations. Such 'basic' optimizations were used by default in old implementation, however they can be really slow on larger expressions. Now, no pre or post optimizations are made by default. postprocess : a function which accepts the two return values of cse and returns the desired form of output from cse, e.g. if you want the replacements reversed the function might be the following lambda: lambda r, e: return reversed(r), e order : string, 'none' or 'canonical' The order by which Mul and Add arguments are processed. If set to 'canonical', arguments will be canonically ordered. If set to 'none', ordering will be faster but dependent on expressions hashes, thus machine dependent and variable. For large expressions where speed is a concern, use the setting order='none'. ignore : iterable of Symbols Substitutions containing any Symbol from ``ignore`` will be ignored. Returns ======= replacements : list of (Symbol, expression) pairs All of the common subexpressions that were replaced. Subexpressions earlier in this list might show up in subexpressions later in this list. reduced_exprs : list of sympy expressions The reduced expressions with all of the replacements above. Examples ======== >>> from sympy import cse, SparseMatrix >>> from sympy.abc import x, y, z, w >>> cse(((w + x + y + z)(w + y + z))/(w + x)3) ([(x0, y + z), (x1, w + x)], [(w + x0)(x0 + x1)/x1*3]) Note that currently, y + z will not get substituted if -y - z is used. >>> cse(((w + x + y + z)(w - y - z))/(w + x)*3) ([(x0, w + x)], [(w - y - z)(x0 + y + z)/x03]) List of expressions with recursive substitutions: >>> m = SparseMatrix([x + y, x + y + z]) >>> cse([(x+y)2, x + y + z, y + z, x + z + y, m]) ([(x0, x + y), (x1, x0 + z)], [x02, x1, y + z, x1, Matrix([ [x0], [x1]])]) Note: the type and mutability of input matrices is retained. >>> isinstance(_[1][-1], SparseMatrix) True The user may disallow substitutions containing certain symbols: >>> cse([y2(x + 1), 3y*2(x + 1)], ignore=(y,)) ([(x0, x + 1)], [x0y2, 3x0y2]) """ from sympy.matrices import (MatrixBase, Matrix, ImmutableMatrix, SparseMatrix, ImmutableSparseMatrix) if isinstance(exprs, (int, float)): exprs = sympify(exprs) # Handle the case if just one expression was passed. if isinstance(exprs, (Basic, MatrixBase)): exprs = [exprs] copy = exprs temp = [] for e in exprs: if isinstance(e, (Matrix, ImmutableMatrix)): temp.append(Tuple(e._mat)) elif isinstance(e, (SparseMatrix, ImmutableSparseMatrix)): temp.append(Tuple(*e._smat.items())) else: temp.append(e) exprs = temp del temp if optimizations is None: optimizations = list() elif optimizations == 'basic': optimizations = basic_optimizations # Preprocess the expressions to give us better optimization opportunities. reduced_exprs = [preprocess_for_cse(e, optimizations) for e in exprs] if symbols is None: symbols = numbered_symbols(cls=Symbol) else: # In case we get passed an iterable with an __iter__ method instead of # an actual iterator. symbols = iter(symbols) # Find other optimization opportunities. opt_subs = opt_cse(reduced_exprs, order) # Main CSE algorithm. replacements, reduced_exprs = tree_cse(reduced_exprs, symbols, opt_subs, order, ignore) # Postprocess the expressions to return the expressions to canonical form. exprs = copy for i, (sym, subtree) in enumerate(replacements): subtree = postprocess_for_cse(subtree, optimizations) replacements[i] = (sym, subtree) reduced_exprs = [postprocess_for_cse(e, optimizations) for e in reduced_exprs] # Get the matrices back for i, e in enumerate(exprs): if isinstance(e, (Matrix, ImmutableMatrix)): reduced_exprs[i] = Matrix(e.rows, e.cols, reduced_exprs[i]) if isinstance(e, ImmutableMatrix): reduced_exprs[i] = reduced_exprs[i].as_immutable() elif isinstance(e, (SparseMatrix, ImmutableSparseMatrix)): m = SparseMatrix(e.rows, e.cols, {}) for k, v in reduced_exprs[i]: m[k] = v if isinstance(e, ImmutableSparseMatrix): m = m.as_immutable() reduced_exprs[i] = m if postprocess is None: return replacements, reduced_exprs return postprocess(replacements, reduced_exprs)
8d324c97d3ebc94a6b3d68e9297986e235cb789a1e6db3cca127eb285e44666c	""" Implementation of the trigsimp algorithm by Fu et al. The idea behind the ``fu`` algorithm is to use a sequence of rules, applied in what is heuristically known to be a smart order, to select a simpler expression that is equivalent to the input. There are transform rules in which a single rule is applied to the expression tree. The following are just mnemonic in nature; see the docstrings for examples. TR0 - simplify expression TR1 - sec-csc to cos-sin TR2 - tan-cot to sin-cos ratio TR2i - sin-cos ratio to tan TR3 - angle canonicalization TR4 - functions at special angles TR5 - powers of sin to powers of cos TR6 - powers of cos to powers of sin TR7 - reduce cos power (increase angle) TR8 - expand products of sin-cos to sums TR9 - contract sums of sin-cos to products TR10 - separate sin-cos arguments TR10i - collect sin-cos arguments TR11 - reduce double angles TR12 - separate tan arguments TR12i - collect tan arguments TR13 - expand product of tan-cot TRmorrie - prod(cos(x2i), (i, 0, k - 1)) -> sin(2kx)/(2*ksin(x)) TR14 - factored powers of sin or cos to cos or sin power TR15 - negative powers of sin to cot power TR16 - negative powers of cos to tan power TR22 - tan-cot powers to negative powers of sec-csc functions TR111 - negative sin-cos-tan powers to csc-sec-cot There are 4 combination transforms (CTR1 - CTR4) in which a sequence of transformations are applied and the simplest expression is selected from a few options. Finally, there are the 2 rule lists (RL1 and RL2), which apply a sequence of transformations and combined transformations, and the ``fu`` algorithm itself, which applies rules and rule lists and selects the best expressions. There is also a function ``L`` which counts the number of trigonometric functions that appear in the expression. Other than TR0, re-writing of expressions is not done by the transformations. e.g. TR10i finds pairs of terms in a sum that are in the form like ``cos(x)cos(y) + sin(x)sin(y)``. Such expression are targeted in a bottom-up traversal of the expression, but no manipulation to make them appear is attempted. For example, Set-up for examples below: >>> from sympy.simplify.fu import fu, L, TR9, TR10i, TR11 >>> from sympy import factor, sin, cos, powsimp >>> from sympy.abc import x, y, z, a >>> from time import time >>> eq = cos(x + y)/cos(x) >>> TR10i(eq.expand(trig=True)) -sin(x)sin(y)/cos(x) + cos(y) If the expression is put in "normal" form (with a common denominator) then the transformation is successful: >>> TR10i(_.normal()) cos(x + y)/cos(x) TR11's behavior is similar. It rewrites double angles as smaller angles but doesn't do any simplification of the result. >>> TR11(sin(2)acos(1)*(-a), 1) (2sin(1)cos(1))acos(1)*(-a) >>> powsimp(_) (2sin(1))*a The temptation is to try make these TR rules "smarter" but that should really be done at a higher level; the TR rules should try maintain the "do one thing well" principle. There is one exception, however. In TR10i and TR9 terms are recognized even when they are each multiplied by a common factor: >>> fu(acos(x)cos(y) + asin(x)sin(y)) acos(x - y) Factoring with ``factor_terms`` is used but it it "JIT"-like, being delayed until it is deemed necessary. Furthermore, if the factoring does not help with the simplification, it is not retained, so ``acos(x)cos(y) + asin(x)sin(z)`` does not become the factored (but unsimplified in the trigonometric sense) expression: >>> fu(acos(x)cos(y) + asin(x)sin(z)) asin(x)sin(z) + acos(x)cos(y) In some cases factoring might be a good idea, but the user is left to make that decision. For example: >>> expr=((15sin(2x) + 19sin(x + y) + 17sin(x + z) + 19cos(x - z) + ... 25)(20sin(2x) + 15sin(x + y) + sin(y + z) + 14cos(x - z) + ... 14cos(y - z))(9sin(2y) + 12sin(y + z) + 10cos(x - y) + 2cos(y - ... z) + 18)).expand(trig=True).expand() In the expanded state, there are nearly 1000 trig functions: >>> L(expr) 932 If the expression where factored first, this would take time but the resulting expression would be transformed very quickly: >>> def clock(f, n=2): ... t=time(); f(); return round(time()-t, n) ... >>> clock(lambda: factor(expr)) # doctest: +SKIP 0.86 >>> clock(lambda: TR10i(expr), 3) # doctest: +SKIP 0.016 If the unexpanded expression is used, the transformation takes longer but not as long as it took to factor it and then transform it: >>> clock(lambda: TR10i(expr), 2) # doctest: +SKIP 0.28 So neither expansion nor factoring is used in ``TR10i``: if the expression is already factored (or partially factored) then expansion with ``trig=True`` would destroy what is already known and take longer; if the expression is expanded, factoring may take longer than simply applying the transformation itself. Although the algorithms should be canonical, always giving the same result, they may not yield the best result. This, in general, is the nature of simplification where searching all possible transformation paths is very expensive. Here is a simple example. There are 6 terms in the following sum: >>> expr = (sin(x)2cos(y)cos(z) + sin(x)sin(y)cos(x)cos(z) + ... sin(x)sin(z)cos(x)cos(y) + sin(y)sin(z)cos(x)2 + sin(y)sin(z) + ... cos(y)cos(z)) >>> args = expr.args Serendipitously, fu gives the best result: >>> fu(expr) 3cos(y - z)/2 - cos(2x + y + z)/2 But if different terms were combined, a less-optimal result might be obtained, requiring some additional work to get better simplification, but still less than optimal. The following shows an alternative form of ``expr`` that resists optimal simplification once a given step is taken since it leads to a dead end: >>> TR9(-cos(x)2cos(y + z) + 3cos(y - z)/2 + ... cos(y + z)/2 + cos(-2x + y + z)/4 - cos(2x + y + z)/4) sin(2x)sin(y + z)/2 - cos(x)2cos(y + z) + 3cos(y - z)/2 + cos(y + z)/2 Here is a smaller expression that exhibits the same behavior: >>> a = sin(x)sin(z)cos(x)cos(y) + sin(x)sin(y)cos(x)cos(z) >>> TR10i(a) sin(x)sin(y + z)cos(x) >>> newa = _ >>> TR10i(expr - a) # this combines two more of the remaining terms sin(x)2cos(y)cos(z) + sin(y)sin(z)cos(x)2 + cos(y - z) >>> TR10i(_ + newa) == _ + newa # but now there is no more simplification True Without getting lucky or trying all possible pairings of arguments, the final result may be less than optimal and impossible to find without better heuristics or brute force trial of all possibilities. Notes ===== This work was started by Dimitar Vlahovski at the Technological School "Electronic systems" (30.11.2011). References ========== Fu, Hongguang, Xiuqin Zhong, and Zhenbing Zeng. "Automated and readable simplification of trigonometric expressions." Mathematical and computer modelling 44.11 (2006): 1169-1177. http://rfdz.ph-noe.ac.at/fileadmin/Mathematik_Uploads/ACDCA/DESTIME2006/DES_contribs/Fu/simplification.pdf http://www.sosmath.com/trig/Trig5/trig5/pdf/pdf.html gives a formula sheet. """ from __future__ import print_function, division from collections import defaultdict from sympy.core.add import Add from sympy.core.basic import S from sympy.core.compatibility import ordered, range from sympy.core.expr import Expr from sympy.core.exprtools import Factors, gcd_terms, factor_terms from sympy.core.function import expand_mul from sympy.core.mul import Mul from sympy.core.numbers import pi, I from sympy.core.power import Pow from sympy.core.symbol import Dummy from sympy.core.sympify import sympify from sympy.functions.combinatorial.factorials import binomial from sympy.functions.elementary.hyperbolic import ( cosh, sinh, tanh, coth, sech, csch, HyperbolicFunction) from sympy.functions.elementary.trigonometric import ( cos, sin, tan, cot, sec, csc, sqrt, TrigonometricFunction) from sympy.ntheory.factor_ import perfect_power from sympy.polys.polytools import factor from sympy.simplify.simplify import bottom_up from sympy.strategies.tree import greedy from sympy.strategies.core import identity, debug from sympy import SYMPY_DEBUG # ================== Fu-like tools =========================== def TR0(rv): """Simplification of rational polynomials, trying to simplify the expression, e.g. combine things like 3x + 2x, etc.... """ # although it would be nice to use cancel, it doesn't work # with noncommutatives return rv.normal().factor().expand() def TR1(rv): """Replace sec, csc with 1/cos, 1/sin Examples ======== >>> from sympy.simplify.fu import TR1, sec, csc >>> from sympy.abc import x >>> TR1(2csc(x) + sec(x)) 1/cos(x) + 2/sin(x) """ def f(rv): if isinstance(rv, sec): a = rv.args[0] return S.One/cos(a) elif isinstance(rv, csc): a = rv.args[0] return S.One/sin(a) return rv return bottom_up(rv, f) def TR2(rv): """Replace tan and cot with sin/cos and cos/sin Examples ======== >>> from sympy.simplify.fu import TR2 >>> from sympy.abc import x >>> from sympy import tan, cot, sin, cos >>> TR2(tan(x)) sin(x)/cos(x) >>> TR2(cot(x)) cos(x)/sin(x) >>> TR2(tan(tan(x) - sin(x)/cos(x))) 0 """ def f(rv): if isinstance(rv, tan): a = rv.args[0] return sin(a)/cos(a) elif isinstance(rv, cot): a = rv.args[0] return cos(a)/sin(a) return rv return bottom_up(rv, f) def TR2i(rv, half=False): """Converts ratios involving sin and cos as follows:: sin(x)/cos(x) -> tan(x) sin(x)/(cos(x) + 1) -> tan(x/2) if half=True Examples ======== >>> from sympy.simplify.fu import TR2i >>> from sympy.abc import x, a >>> from sympy import sin, cos >>> TR2i(sin(x)/cos(x)) tan(x) Powers of the numerator and denominator are also recognized >>> TR2i(sin(x)2/(cos(x) + 1)2, half=True) tan(x/2)2 The transformation does not take place unless assumptions allow (i.e. the base must be positive or the exponent must be an integer for both numerator and denominator) >>> TR2i(sin(x)a/(cos(x) + 1)a) (cos(x) + 1)(-a)sin(x)a """ def f(rv): if not rv.is_Mul: return rv n, d = rv.as_numer_denom() if n.is_Atom or d.is_Atom: return rv def ok(k, e): # initial filtering of factors return ( (e.is_integer or k.is_positive) and ( k.func in (sin, cos) or (half and k.is_Add and len(k.args) >= 2 and any(any(isinstance(ai, cos) or ai.is_Pow and ai.base is cos for ai in Mul.make_args(a)) for a in k.args)))) n = n.as_powers_dict() ndone = [(k, n.pop(k)) for k in list(n.keys()) if not ok(k, n[k])] if not n: return rv d = d.as_powers_dict() ddone = [(k, d.pop(k)) for k in list(d.keys()) if not ok(k, d[k])] if not d: return rv # factoring if necessary def factorize(d, ddone): newk = [] for k in d: if k.is_Add and len(k.args) > 1: knew = factor(k) if half else factor_terms(k) if knew != k: newk.append((k, knew)) if newk: for i, (k, knew) in enumerate(newk): del d[k] newk[i] = knew newk = Mul(newk).as_powers_dict() for k in newk: v = d[k] + newk[k] if ok(k, v): d[k] = v else: ddone.append((k, v)) del newk factorize(n, ndone) factorize(d, ddone) # joining t = [] for k in n: if isinstance(k, sin): a = cos(k.args[0], evaluate=False) if a in d and d[a] == n[k]: t.append(tan(k.args[0])n[k]) n[k] = d[a] = None elif half: a1 = 1 + a if a1 in d and d[a1] == n[k]: t.append((tan(k.args[0]/2))n[k]) n[k] = d[a1] = None elif isinstance(k, cos): a = sin(k.args[0], evaluate=False) if a in d and d[a] == n[k]: t.append(tan(k.args[0])-n[k]) n[k] = d[a] = None elif half and k.is_Add and k.args[0] is S.One and \ isinstance(k.args[1], cos): a = sin(k.args[1].args[0], evaluate=False) if a in d and d[a] == n[k] and (d[a].is_integer or \ a.is_positive): t.append(tan(a.args[0]/2)-n[k]) n[k] = d[a] = None if t: rv = Mul((t + [be for b, e in n.items() if e]))/\ Mul([b*e for b, e in d.items() if e]) rv = Mul([be for b, e in ndone])/Mul([b*e for b, e in ddone]) return rv return bottom_up(rv, f) def TR3(rv): """Induced formula: example sin(-a) = -sin(a) Examples ======== >>> from sympy.simplify.fu import TR3 >>> from sympy.abc import x, y >>> from sympy import pi >>> from sympy import cos >>> TR3(cos(y - x(y - x))) cos(x(x - y) + y) >>> cos(pi/2 + x) -sin(x) >>> cos(30pi/2 + x) -cos(x) """ from sympy.simplify.simplify import signsimp # Negative argument (already automatic for funcs like sin(-x) -> -sin(x) # but more complicated expressions can use it, too). Also, trig angles # between pi/4 and pi/2 are not reduced to an angle between 0 and pi/4. # The following are automatically handled: # Argument of type: pi/2 +/- angle # Argument of type: pi +/- angle # Argument of type : 2kpi +/- angle def f(rv): if not isinstance(rv, TrigonometricFunction): return rv rv = rv.func(signsimp(rv.args[0])) if not isinstance(rv, TrigonometricFunction): return rv if (rv.args[0] - S.Pi/4).is_positive is (S.Pi/2 - rv.args[0]).is_positive is True: fmap = {cos: sin, sin: cos, tan: cot, cot: tan, sec: csc, csc: sec} rv = fmap[rv.func](S.Pi/2 - rv.args[0]) return rv return bottom_up(rv, f) def TR4(rv): """Identify values of special angles. a= 0 pi/6 pi/4 pi/3 pi/2 ---------------------------------------------------- cos(a) 0 1/2 sqrt(2)/2 sqrt(3)/2 1 sin(a) 1 sqrt(3)/2 sqrt(2)/2 1/2 0 tan(a) 0 sqt(3)/3 1 sqrt(3) -- Examples ======== >>> from sympy.simplify.fu import TR4 >>> from sympy import pi >>> from sympy import cos, sin, tan, cot >>> for s in (0, pi/6, pi/4, pi/3, pi/2): ... print('%s %s %s %s' % (cos(s), sin(s), tan(s), cot(s))) ... 1 0 0 zoo sqrt(3)/2 1/2 sqrt(3)/3 sqrt(3) sqrt(2)/2 sqrt(2)/2 1 1 1/2 sqrt(3)/2 sqrt(3) sqrt(3)/3 0 1 zoo 0 """ # special values at 0, pi/6, pi/4, pi/3, pi/2 already handled return rv def _TR56(rv, f, g, h, max, pow): """Helper for TR5 and TR6 to replace f2 with h(g2) Options ======= max : controls size of exponent that can appear on f e.g. if max=4 then f4 will be changed to h(g2)2. pow : controls whether the exponent must be a perfect power of 2 e.g. if pow=True (and max >= 6) then f6 will not be changed but f8 will be changed to h(g2)4 >>> from sympy.simplify.fu import _TR56 as T >>> from sympy.abc import x >>> from sympy import sin, cos >>> h = lambda x: 1 - x >>> T(sin(x)3, sin, cos, h, 4, False) sin(x)3 >>> T(sin(x)6, sin, cos, h, 6, False) (-cos(x)2 + 1)3 >>> T(sin(x)6, sin, cos, h, 6, True) sin(x)6 >>> T(sin(x)8, sin, cos, h, 10, True) (-cos(x)2 + 1)4 """ def _f(rv): # I'm not sure if this transformation should target all even powers # or only those expressible as powers of 2. Also, should it only # make the changes in powers that appear in sums -- making an isolated # change is not going to allow a simplification as far as I can tell. if not (rv.is_Pow and rv.base.func == f): return rv if (rv.exp < 0) == True: return rv if (rv.exp > max) == True: return rv if rv.exp == 2: return h(g(rv.base.args[0])2) else: if rv.exp == 4: e = 2 elif not pow: if rv.exp % 2: return rv e = rv.exp//2 else: p = perfect_power(rv.exp) if not p: return rv e = rv.exp//2 return h(g(rv.base.args[0])2)e return bottom_up(rv, _f) def TR5(rv, max=4, pow=False): """Replacement of sin2 with 1 - cos(x)2. See _TR56 docstring for advanced use of ``max`` and ``pow``. Examples ======== >>> from sympy.simplify.fu import TR5 >>> from sympy.abc import x >>> from sympy import sin >>> TR5(sin(x)2) -cos(x)2 + 1 >>> TR5(sin(x)-2) # unchanged sin(x)(-2) >>> TR5(sin(x)4) (-cos(x)2 + 1)2 """ return _TR56(rv, sin, cos, lambda x: 1 - x, max=max, pow=pow) def TR6(rv, max=4, pow=False): """Replacement of cos2 with 1 - sin(x)2. See _TR56 docstring for advanced use of ``max`` and ``pow``. Examples ======== >>> from sympy.simplify.fu import TR6 >>> from sympy.abc import x >>> from sympy import cos >>> TR6(cos(x)2) -sin(x)2 + 1 >>> TR6(cos(x)-2) #unchanged cos(x)(-2) >>> TR6(cos(x)4) (-sin(x)2 + 1)2 """ return _TR56(rv, cos, sin, lambda x: 1 - x, max=max, pow=pow) def TR7(rv): """Lowering the degree of cos(x)2 Examples ======== >>> from sympy.simplify.fu import TR7 >>> from sympy.abc import x >>> from sympy import cos >>> TR7(cos(x)2) cos(2x)/2 + 1/2 >>> TR7(cos(x)*2 + 1) cos(2x)/2 + 3/2 """ def f(rv): if not (rv.is_Pow and rv.base.func == cos and rv.exp == 2): return rv return (1 + cos(2rv.base.args[0]))/2 return bottom_up(rv, f) def TR8(rv, first=True): """Converting products of ``cos`` and/or ``sin`` to a sum or difference of ``cos`` and or ``sin`` terms. Examples ======== >>> from sympy.simplify.fu import TR8, TR7 >>> from sympy import cos, sin >>> TR8(cos(2)cos(3)) cos(5)/2 + cos(1)/2 >>> TR8(cos(2)sin(3)) sin(5)/2 + sin(1)/2 >>> TR8(sin(2)sin(3)) -cos(5)/2 + cos(1)/2 """ def f(rv): if not ( rv.is_Mul or rv.is_Pow and rv.base.func in (cos, sin) and (rv.exp.is_integer or rv.base.is_positive)): return rv if first: n, d = [expand_mul(i) for i in rv.as_numer_denom()] newn = TR8(n, first=False) newd = TR8(d, first=False) if newn != n or newd != d: rv = gcd_terms(newn/newd) if rv.is_Mul and rv.args[0].is_Rational and \ len(rv.args) == 2 and rv.args[1].is_Add: rv = Mul(rv.as_coeff_Mul()) return rv args = {cos: [], sin: [], None: []} for a in ordered(Mul.make_args(rv)): if a.func in (cos, sin): args[a.func].append(a.args[0]) elif (a.is_Pow and a.exp.is_Integer and a.exp > 0 and \ a.base.func in (cos, sin)): # XXX this is ok but pathological expression could be handled # more efficiently as in TRmorrie args[a.base.func].extend([a.base.args[0]]a.exp) else: args[None].append(a) c = args[cos] s = args[sin] if not (c and s or len(c) > 1 or len(s) > 1): return rv args = args[None] n = min(len(c), len(s)) for i in range(n): a1 = s.pop() a2 = c.pop() args.append((sin(a1 + a2) + sin(a1 - a2))/2) while len(c) > 1: a1 = c.pop() a2 = c.pop() args.append((cos(a1 + a2) + cos(a1 - a2))/2) if c: args.append(cos(c.pop())) while len(s) > 1: a1 = s.pop() a2 = s.pop() args.append((-cos(a1 + a2) + cos(a1 - a2))/2) if s: args.append(sin(s.pop())) return TR8(expand_mul(Mul(args))) return bottom_up(rv, f) def TR9(rv): """Sum of ``cos`` or ``sin`` terms as a product of ``cos`` or ``sin``. Examples ======== >>> from sympy.simplify.fu import TR9 >>> from sympy import cos, sin >>> TR9(cos(1) + cos(2)) 2cos(1/2)cos(3/2) >>> TR9(cos(1) + 2sin(1) + 2sin(2)) cos(1) + 4sin(3/2)cos(1/2) If no change is made by TR9, no re-arrangement of the expression will be made. For example, though factoring of common term is attempted, if the factored expression wasn't changed, the original expression will be returned: >>> TR9(cos(3) + cos(3)cos(2)) cos(3) + cos(2)cos(3) """ def f(rv): if not rv.is_Add: return rv def do(rv, first=True): # cos(a)+/-cos(b) can be combined into a product of cosines and # sin(a)+/-sin(b) can be combined into a product of cosine and # sine. # # If there are more than two args, the pairs which "work" will # have a gcd extractable and the remaining two terms will have # the above structure -- all pairs must be checked to find the # ones that work. args that don't have a common set of symbols # are skipped since this doesn't lead to a simpler formula and # also has the arbitrariness of combining, for example, the x # and y term instead of the y and z term in something like # cos(x) + cos(y) + cos(z). if not rv.is_Add: return rv args = list(ordered(rv.args)) if len(args) != 2: hit = False for i in range(len(args)): ai = args[i] if ai is None: continue for j in range(i + 1, len(args)): aj = args[j] if aj is None: continue was = ai + aj new = do(was) if new != was: args[i] = new # update in place args[j] = None hit = True break # go to next i if hit: rv = Add([_f for _f in args if _f]) if rv.is_Add: rv = do(rv) return rv # two-arg Add split = trig_split(args) if not split: return rv gcd, n1, n2, a, b, iscos = split # application of rule if possible if iscos: if n1 == n2: return gcdn12cos((a + b)/2)cos((a - b)/2) if n1 < 0: a, b = b, a return -2gcdsin((a + b)/2)sin((a - b)/2) else: if n1 == n2: return gcdn12sin((a + b)/2)cos((a - b)/2) if n1 < 0: a, b = b, a return 2gcdcos((a + b)/2)sin((a - b)/2) return process_common_addends(rv, do) # DON'T sift by free symbols return bottom_up(rv, f) def TR10(rv, first=True): """Separate sums in ``cos`` and ``sin``. Examples ======== >>> from sympy.simplify.fu import TR10 >>> from sympy.abc import a, b, c >>> from sympy import cos, sin >>> TR10(cos(a + b)) -sin(a)sin(b) + cos(a)cos(b) >>> TR10(sin(a + b)) sin(a)cos(b) + sin(b)cos(a) >>> TR10(sin(a + b + c)) (-sin(a)sin(b) + cos(a)cos(b))sin(c) + \ (sin(a)cos(b) + sin(b)cos(a))cos(c) """ def f(rv): if not rv.func in (cos, sin): return rv f = rv.func arg = rv.args[0] if arg.is_Add: if first: args = list(ordered(arg.args)) else: args = list(arg.args) a = args.pop() b = Add._from_args(args) if b.is_Add: if f == sin: return sin(a)TR10(cos(b), first=False) + \ cos(a)TR10(sin(b), first=False) else: return cos(a)TR10(cos(b), first=False) - \ sin(a)TR10(sin(b), first=False) else: if f == sin: return sin(a)cos(b) + cos(a)sin(b) else: return cos(a)cos(b) - sin(a)sin(b) return rv return bottom_up(rv, f) def TR10i(rv): """Sum of products to function of sum. Examples ======== >>> from sympy.simplify.fu import TR10i >>> from sympy import cos, sin, pi, Add, Mul, sqrt, Symbol >>> from sympy.abc import x, y >>> TR10i(cos(1)cos(3) + sin(1)sin(3)) cos(2) >>> TR10i(cos(1)sin(3) + sin(1)cos(3) + cos(3)) cos(3) + sin(4) >>> TR10i(sqrt(2)cos(x)x + sqrt(6)sin(x)x) 2sqrt(2)xsin(x + pi/6) """ global _ROOT2, _ROOT3, _invROOT3 if _ROOT2 is None: _roots() def f(rv): if not rv.is_Add: return rv def do(rv, first=True): # args which can be expressed as A(cos(a)cos(b)+/-sin(a)sin(b)) # or B(cos(a)sin(b)+/-cos(b)sin(a)) can be combined into # Af(a+/-b) where f is either sin or cos. # # If there are more than two args, the pairs which "work" will have # a gcd extractable and the remaining two terms will have the above # structure -- all pairs must be checked to find the ones that # work. if not rv.is_Add: return rv args = list(ordered(rv.args)) if len(args) != 2: hit = False for i in range(len(args)): ai = args[i] if ai is None: continue for j in range(i + 1, len(args)): aj = args[j] if aj is None: continue was = ai + aj new = do(was) if new != was: args[i] = new # update in place args[j] = None hit = True break # go to next i if hit: rv = Add([_f for _f in args if _f]) if rv.is_Add: rv = do(rv) return rv # two-arg Add split = trig_split(args, two=True) if not split: return rv gcd, n1, n2, a, b, same = split # identify and get c1 to be cos then apply rule if possible if same: # coscos, sinsin gcd = n1gcd if n1 == n2: return gcdcos(a - b) return gcdcos(a + b) else: #cossin, cossin gcd = n1gcd if n1 == n2: return gcdsin(a + b) return gcdsin(b - a) rv = process_common_addends( rv, do, lambda x: tuple(ordered(x.free_symbols))) # need to check for inducible pairs in ratio of sqrt(3):1 that # appeared in different lists when sorting by coefficient while rv.is_Add: byrad = defaultdict(list) for a in rv.args: hit = 0 if a.is_Mul: for ai in a.args: if ai.is_Pow and ai.exp is S.Half and \ ai.base.is_Integer: byrad[ai].append(a) hit = 1 break if not hit: byrad[S.One].append(a) # no need to check all pairs -- just check for the onees # that have the right ratio args = [] for a in byrad: for b in [_ROOT3a, _invROOT3]: if b in byrad: for i in range(len(byrad[a])): if byrad[a][i] is None: continue for j in range(len(byrad[b])): if byrad[b][j] is None: continue was = Add(byrad[a][i] + byrad[b][j]) new = do(was) if new != was: args.append(new) byrad[a][i] = None byrad[b][j] = None break if args: rv = Add((args + [Add([_f for _f in v if _f]) for v in byrad.values()])) else: rv = do(rv) # final pass to resolve any new inducible pairs break return rv return bottom_up(rv, f) def TR11(rv, base=None): """Function of double angle to product. The ``base`` argument can be used to indicate what is the un-doubled argument, e.g. if 3pi/7 is the base then cosine and sine functions with argument 6pi/7 will be replaced. Examples ======== >>> from sympy.simplify.fu import TR11 >>> from sympy import cos, sin, pi >>> from sympy.abc import x >>> TR11(sin(2x)) 2sin(x)cos(x) >>> TR11(cos(2x)) -sin(x)2 + cos(x)2 >>> TR11(sin(4x)) 4(-sin(x)2 + cos(x)2)sin(x)cos(x) >>> TR11(sin(4x/3)) 4(-sin(x/3)2 + cos(x/3)2)sin(x/3)cos(x/3) If the arguments are simply integers, no change is made unless a base is provided: >>> TR11(cos(2)) cos(2) >>> TR11(cos(4), 2) -sin(2)2 + cos(2)2 There is a subtle issue here in that autosimplification will convert some higher angles to lower angles >>> cos(6pi/7) + cos(3pi/7) -cos(pi/7) + cos(3pi/7) The 6pi/7 angle is now pi/7 but can be targeted with TR11 by supplying the 3pi/7 base: >>> TR11(_, 3pi/7) -sin(3pi/7)2 + cos(3pi/7)*2 + cos(3pi/7) """ def f(rv): if not rv.func in (cos, sin): return rv if base: f = rv.func t = f(base2) co = S.One if t.is_Mul: co, t = t.as_coeff_Mul() if not t.func in (cos, sin): return rv if rv.args[0] == t.args[0]: c = cos(base) s = sin(base) if f is cos: return (c2 - s2)/co else: return 2cs/co return rv elif not rv.args[0].is_Number: # make a change if the leading coefficient's numerator is # divisible by 2 c, m = rv.args[0].as_coeff_Mul(rational=True) if c.p % 2 == 0: arg = c.p//2m/c.q c = TR11(cos(arg)) s = TR11(sin(arg)) if rv.func == sin: rv = 2sc else: rv = c2 - s2 return rv return bottom_up(rv, f) def TR12(rv, first=True): """Separate sums in ``tan``. Examples ======== >>> from sympy.simplify.fu import TR12 >>> from sympy.abc import x, y >>> from sympy import tan >>> from sympy.simplify.fu import TR12 >>> TR12(tan(x + y)) (tan(x) + tan(y))/(-tan(x)tan(y) + 1) """ def f(rv): if not rv.func == tan: return rv arg = rv.args[0] if arg.is_Add: if first: args = list(ordered(arg.args)) else: args = list(arg.args) a = args.pop() b = Add._from_args(args) if b.is_Add: tb = TR12(tan(b), first=False) else: tb = tan(b) return (tan(a) + tb)/(1 - tan(a)tb) return rv return bottom_up(rv, f) def TR12i(rv): """Combine tan arguments as (tan(y) + tan(x))/(tan(x)tan(y) - 1) -> -tan(x + y) Examples ======== >>> from sympy.simplify.fu import TR12i >>> from sympy import tan >>> from sympy.abc import a, b, c >>> ta, tb, tc = [tan(i) for i in (a, b, c)] >>> TR12i((ta + tb)/(-tatb + 1)) tan(a + b) >>> TR12i((ta + tb)/(tatb - 1)) -tan(a + b) >>> TR12i((-ta - tb)/(tatb - 1)) tan(a + b) >>> eq = (ta + tb)/(-tatb + 1)2(-3ta - 3tc)/(2(tatc - 1)) >>> TR12i(eq.expand()) -3tan(a + b)tan(a + c)/(2(tan(a) + tan(b) - 1)) """ from sympy import factor def f(rv): if not (rv.is_Add or rv.is_Mul or rv.is_Pow): return rv n, d = rv.as_numer_denom() if not d.args or not n.args: return rv dok = {} def ok(di): m = as_f_sign_1(di) if m: g, f, s = m if s is S.NegativeOne and f.is_Mul and len(f.args) == 2 and \ all(isinstance(fi, tan) for fi in f.args): return g, f d_args = list(Mul.make_args(d)) for i, di in enumerate(d_args): m = ok(di) if m: g, t = m s = Add([_.args[0] for _ in t.args]) dok[s] = S.One d_args[i] = g continue if di.is_Add: di = factor(di) if di.is_Mul: d_args.extend(di.args) d_args[i] = S.One elif di.is_Pow and (di.exp.is_integer or di.base.is_positive): m = ok(di.base) if m: g, t = m s = Add([_.args[0] for _ in t.args]) dok[s] = di.exp d_args[i] = gdi.exp else: di = factor(di) if di.is_Mul: d_args.extend(di.args) d_args[i] = S.One if not dok: return rv def ok(ni): if ni.is_Add and len(ni.args) == 2: a, b = ni.args if isinstance(a, tan) and isinstance(b, tan): return a, b n_args = list(Mul.make_args(factor_terms(n))) hit = False for i, ni in enumerate(n_args): m = ok(ni) if not m: m = ok(-ni) if m: n_args[i] = S.NegativeOne else: if ni.is_Add: ni = factor(ni) if ni.is_Mul: n_args.extend(ni.args) n_args[i] = S.One continue elif ni.is_Pow and ( ni.exp.is_integer or ni.base.is_positive): m = ok(ni.base) if m: n_args[i] = S.One else: ni = factor(ni) if ni.is_Mul: n_args.extend(ni.args) n_args[i] = S.One continue else: continue else: n_args[i] = S.One hit = True s = Add([_.args[0] for _ in m]) ed = dok[s] newed = ed.extract_additively(S.One) if newed is not None: if newed: dok[s] = newed else: dok.pop(s) n_args[i] = -tan(s) if hit: rv = Mul(n_args)/Mul(d_args)/Mul([(Add([ tan(a) for a in i.args]) - 1)e for i, e in dok.items()]) return rv return bottom_up(rv, f) def TR13(rv): """Change products of ``tan`` or ``cot``. Examples ======== >>> from sympy.simplify.fu import TR13 >>> from sympy import tan, cot, cos >>> TR13(tan(3)tan(2)) -tan(2)/tan(5) - tan(3)/tan(5) + 1 >>> TR13(cot(3)cot(2)) cot(2)cot(5) + 1 + cot(3)cot(5) """ def f(rv): if not rv.is_Mul: return rv # XXX handle products of powers? or let power-reducing handle it? args = {tan: [], cot: [], None: []} for a in ordered(Mul.make_args(rv)): if a.func in (tan, cot): args[a.func].append(a.args[0]) else: args[None].append(a) t = args[tan] c = args[cot] if len(t) < 2 and len(c) < 2: return rv args = args[None] while len(t) > 1: t1 = t.pop() t2 = t.pop() args.append(1 - (tan(t1)/tan(t1 + t2) + tan(t2)/tan(t1 + t2))) if t: args.append(tan(t.pop())) while len(c) > 1: t1 = c.pop() t2 = c.pop() args.append(1 + cot(t1)cot(t1 + t2) + cot(t2)cot(t1 + t2)) if c: args.append(cot(c.pop())) return Mul(args) return bottom_up(rv, f) def TRmorrie(rv): """Returns cos(x)cos(2x)...cos(2*(k-1)x) -> sin(2*kx)/(2*ksin(x)) Examples ======== >>> from sympy.simplify.fu import TRmorrie, TR8, TR3 >>> from sympy.abc import x >>> from sympy import Mul, cos, pi >>> TRmorrie(cos(x)cos(2x)) sin(4x)/(4sin(x)) >>> TRmorrie(7Mul([cos(x) for x in range(10)])) 7sin(12)sin(16)cos(5)cos(7)cos(9)/(64sin(1)sin(3)) Sometimes autosimplification will cause a power to be not recognized. e.g. in the following, cos(4pi/7) automatically simplifies to -cos(3pi/7) so only 2 of the 3 terms are recognized: >>> TRmorrie(cos(pi/7)cos(2pi/7)cos(4pi/7)) -sin(3pi/7)cos(3pi/7)/(4sin(pi/7)) A touch by TR8 resolves the expression to a Rational >>> TR8(_) -1/8 In this case, if eq is unsimplified, the answer is obtained directly: >>> eq = cos(pi/9)cos(2pi/9)cos(3pi/9)cos(4pi/9) >>> TRmorrie(eq) 1/16 But if angles are made canonical with TR3 then the answer is not simplified without further work: >>> TR3(eq) sin(pi/18)cos(pi/9)cos(2pi/9)/2 >>> TRmorrie(_) sin(pi/18)sin(4pi/9)/(8sin(pi/9)) >>> TR8(_) cos(7pi/18)/(16sin(pi/9)) >>> TR3(_) 1/16 The original expression would have resolve to 1/16 directly with TR8, however: >>> TR8(eq) 1/16 References ========== https://en.wikipedia.org/wiki/Morrie%27s_law """ def f(rv): if not rv.is_Mul: return rv args = defaultdict(list) coss = {} other = [] for c in rv.args: b, e = c.as_base_exp() if e.is_Integer and isinstance(b, cos): co, a = b.args[0].as_coeff_Mul() args[a].append(co) coss[b] = e else: other.append(c) new = [] for a in args: c = args[a] c.sort() no = [] while c: k = 0 cc = ci = c[0] while cc in c: k += 1 cc = 2 if k > 1: newarg = sin(2*kcia)/2k/sin(cia) # see how many times this can be taken take = None ccs = [] for i in range(k): cc /= 2 key = cos(acc, evaluate=False) ccs.append(cc) take = min(coss[key], take or coss[key]) # update exponent counts for i in range(k): cc = ccs.pop() key = cos(acc, evaluate=False) coss[key] -= take if not coss[key]: c.remove(cc) new.append(newarg*take) else: no.append(c.pop(0)) c[:] = no if new: rv = Mul((new + other + [ cos(ka, evaluate=False) for a in args for k in args[a]])) return rv return bottom_up(rv, f) def TR14(rv, first=True): """Convert factored powers of sin and cos identities into simpler expressions. Examples ======== >>> from sympy.simplify.fu import TR14 >>> from sympy.abc import x, y >>> from sympy import cos, sin >>> TR14((cos(x) - 1)(cos(x) + 1)) -sin(x)*2 >>> TR14((sin(x) - 1)(sin(x) + 1)) -cos(x)*2 >>> p1 = (cos(x) + 1)(cos(x) - 1) >>> p2 = (cos(y) - 1)2(cos(y) + 1) >>> p3 = (3(cos(y) - 1))(3(cos(y) + 1)) >>> TR14(p1p2p3(x - 1)) -18(x - 1)sin(x)*2sin(y)4 """ def f(rv): if not rv.is_Mul: return rv if first: # sort them by location in numerator and denominator # so the code below can just deal with positive exponents n, d = rv.as_numer_denom() if d is not S.One: newn = TR14(n, first=False) newd = TR14(d, first=False) if newn != n or newd != d: rv = newn/newd return rv other = [] process = [] for a in rv.args: if a.is_Pow: b, e = a.as_base_exp() if not (e.is_integer or b.is_positive): other.append(a) continue a = b else: e = S.One m = as_f_sign_1(a) if not m or m[1].func not in (cos, sin): if e is S.One: other.append(a) else: other.append(ae) continue g, f, si = m process.append((g, e.is_Number, e, f, si, a)) # sort them to get like terms next to each other process = list(ordered(process)) # keep track of whether there was any change nother = len(other) # access keys keys = (g, t, e, f, si, a) = list(range(6)) while process: A = process.pop(0) if process: B = process[0] if A[e].is_Number and B[e].is_Number: # both exponents are numbers if A[f] == B[f]: if A[si] != B[si]: B = process.pop(0) take = min(A[e], B[e]) # reinsert any remainder # the B will likely sort after A so check it first if B[e] != take: rem = [B[i] for i in keys] rem[e] -= take process.insert(0, rem) elif A[e] != take: rem = [A[i] for i in keys] rem[e] -= take process.insert(0, rem) if isinstance(A[f], cos): t = sin else: t = cos other.append((-A[g]B[g]t(A[f].args[0])2)take) continue elif A[e] == B[e]: # both exponents are equal symbols if A[f] == B[f]: if A[si] != B[si]: B = process.pop(0) take = A[e] if isinstance(A[f], cos): t = sin else: t = cos other.append((-A[g]B[g]t(A[f].args[0])2)take) continue # either we are done or neither condition above applied other.append(A[a]*A[e]) if len(other) != nother: rv = Mul(other) return rv return bottom_up(rv, f) def TR15(rv, max=4, pow=False): """Convert sin(x)-2 to 1 + cot(x)2. See _TR56 docstring for advanced use of ``max`` and ``pow``. Examples ======== >>> from sympy.simplify.fu import TR15 >>> from sympy.abc import x >>> from sympy import cos, sin >>> TR15(1 - 1/sin(x)2) -cot(x)2 """ def f(rv): if not (isinstance(rv, Pow) and isinstance(rv.base, sin)): return rv ia = 1/rv a = _TR56(ia, sin, cot, lambda x: 1 + x, max=max, pow=pow) if a != ia: rv = a return rv return bottom_up(rv, f) def TR16(rv, max=4, pow=False): """Convert cos(x)-2 to 1 + tan(x)2. See _TR56 docstring for advanced use of ``max`` and ``pow``. Examples ======== >>> from sympy.simplify.fu import TR16 >>> from sympy.abc import x >>> from sympy import cos, sin >>> TR16(1 - 1/cos(x)2) -tan(x)2 """ def f(rv): if not (isinstance(rv, Pow) and isinstance(rv.base, cos)): return rv ia = 1/rv a = _TR56(ia, cos, tan, lambda x: 1 + x, max=max, pow=pow) if a != ia: rv = a return rv return bottom_up(rv, f) def TR111(rv): """Convert f(x)-i to g(x)i where either ``i`` is an integer or the base is positive and f, g are: tan, cot; sin, csc; or cos, sec. Examples ======== >>> from sympy.simplify.fu import TR111 >>> from sympy.abc import x >>> from sympy import tan >>> TR111(1 - 1/tan(x)2) -cot(x)2 + 1 """ def f(rv): if not ( isinstance(rv, Pow) and (rv.base.is_positive or rv.exp.is_integer and rv.exp.is_negative)): return rv if isinstance(rv.base, tan): return cot(rv.base.args[0])-rv.exp elif isinstance(rv.base, sin): return csc(rv.base.args[0])-rv.exp elif isinstance(rv.base, cos): return sec(rv.base.args[0])-rv.exp return rv return bottom_up(rv, f) def TR22(rv, max=4, pow=False): """Convert tan(x)2 to sec(x)2 - 1 and cot(x)2 to csc(x)2 - 1. See _TR56 docstring for advanced use of ``max`` and ``pow``. Examples ======== >>> from sympy.simplify.fu import TR22 >>> from sympy.abc import x >>> from sympy import tan, cot >>> TR22(1 + tan(x)2) sec(x)2 >>> TR22(1 + cot(x)2) csc(x)2 """ def f(rv): if not (isinstance(rv, Pow) and rv.base.func in (cot, tan)): return rv rv = _TR56(rv, tan, sec, lambda x: x - 1, max=max, pow=pow) rv = _TR56(rv, cot, csc, lambda x: x - 1, max=max, pow=pow) return rv return bottom_up(rv, f) def TRpower(rv): """Convert sin(x)n and cos(x)n with positive n to sums. Examples ======== >>> from sympy.simplify.fu import TRpower >>> from sympy.abc import x >>> from sympy import cos, sin >>> TRpower(sin(x)*6) -15cos(2x)/32 + 3cos(4x)/16 - cos(6x)/32 + 5/16 >>> TRpower(sin(x)*3cos(2x)4) (3sin(x)/4 - sin(3x)/4)(cos(4x)/2 + cos(8x)/8 + 3/8) References ========== https://en.wikipedia.org/wiki/List_of_trigonometric_identities#Power-reduction_formulae """ def f(rv): if not (isinstance(rv, Pow) and isinstance(rv.base, (sin, cos))): return rv b, n = rv.as_base_exp() x = b.args[0] if n.is_Integer and n.is_positive: if n.is_odd and isinstance(b, cos): rv = 2*(1-n)Add([binomial(n, k)cos((n - 2k)x) for k in range((n + 1)/2)]) elif n.is_odd and isinstance(b, sin): rv = 2*(1-n)(-1)*((n-1)/2)Add([binomial(n, k) (-1)*ksin((n - 2k)x) for k in range((n + 1)/2)]) elif n.is_even and isinstance(b, cos): rv = 2*(1-n)Add([binomial(n, k)cos((n - 2k)x) for k in range(n/2)]) elif n.is_even and isinstance(b, sin): rv = 2*(1-n)(-1)*(n/2)Add([binomial(n, k) (-1)*kcos((n - 2k)x) for k in range(n/2)]) if n.is_even: rv += 2*(-n)binomial(n, n/2) return rv return bottom_up(rv, f) def L(rv): """Return count of trigonometric functions in expression. Examples ======== >>> from sympy.simplify.fu import L >>> from sympy.abc import x >>> from sympy import cos, sin >>> L(cos(x)+sin(x)) 2 """ return S(rv.count(TrigonometricFunction)) # ============== end of basic Fu-like tools ===================== if SYMPY_DEBUG: (TR0, TR1, TR2, TR3, TR4, TR5, TR6, TR7, TR8, TR9, TR10, TR11, TR12, TR13, TR2i, TRmorrie, TR14, TR15, TR16, TR12i, TR111, TR22 )= list(map(debug, (TR0, TR1, TR2, TR3, TR4, TR5, TR6, TR7, TR8, TR9, TR10, TR11, TR12, TR13, TR2i, TRmorrie, TR14, TR15, TR16, TR12i, TR111, TR22))) # tuples are chains -- (f, g) -> lambda x: g(f(x)) # lists are choices -- [f, g] -> lambda x: min(f(x), g(x), key=objective) CTR1 = [(TR5, TR0), (TR6, TR0), identity] CTR2 = (TR11, [(TR5, TR0), (TR6, TR0), TR0]) CTR3 = [(TRmorrie, TR8, TR0), (TRmorrie, TR8, TR10i, TR0), identity] CTR4 = [(TR4, TR10i), identity] RL1 = (TR4, TR3, TR4, TR12, TR4, TR13, TR4, TR0) # XXX it's a little unclear how this one is to be implemented # see Fu paper of reference, page 7. What is the Union symbol referring to? # The diagram shows all these as one chain of transformations, but the # text refers to them being applied independently. Also, a break # if L starts to increase has not been implemented. RL2 = [ (TR4, TR3, TR10, TR4, TR3, TR11), (TR5, TR7, TR11, TR4), (CTR3, CTR1, TR9, CTR2, TR4, TR9, TR9, CTR4), identity, ] def fu(rv, measure=lambda x: (L(x), x.count_ops())): """Attempt to simplify expression by using transformation rules given in the algorithm by Fu et al. :func:`fu` will try to minimize the objective function ``measure``. By default this first minimizes the number of trig terms and then minimizes the number of total operations. Examples ======== >>> from sympy.simplify.fu import fu >>> from sympy import cos, sin, tan, pi, S, sqrt >>> from sympy.abc import x, y, a, b >>> fu(sin(50)2 + cos(50)2 + sin(pi/6)) 3/2 >>> fu(sqrt(6)cos(x) + sqrt(2)sin(x)) 2sqrt(2)sin(x + pi/3) CTR1 example >>> eq = sin(x)4 - cos(y)2 + sin(y)*2 + 2cos(x)2 >>> fu(eq) cos(x)4 - 2cos(y)2 + 2 CTR2 example >>> fu(S.Half - cos(2x)/2) sin(x)*2 CTR3 example >>> fu(sin(a)(cos(b) - sin(b)) + cos(a)(sin(b) + cos(b))) sqrt(2)sin(a + b + pi/4) CTR4 example >>> fu(sqrt(3)cos(x)/2 + sin(x)/2) sin(x + pi/3) Example 1 >>> fu(1-sin(2x)2/4-sin(y)2-cos(x)4) -cos(x)2 + cos(y)*2 Example 2 >>> fu(cos(4pi/9)) sin(pi/18) >>> fu(cos(pi/9)cos(2pi/9)cos(3pi/9)cos(4pi/9)) 1/16 Example 3 >>> fu(tan(7pi/18)+tan(5pi/18)-sqrt(3)tan(5pi/18)tan(7pi/18)) -sqrt(3) Objective function example >>> fu(sin(x)/cos(x)) # default objective function tan(x) >>> fu(sin(x)/cos(x), measure=lambda x: -x.count_ops()) # maximize op count sin(x)/cos(x) References ========== http://rfdz.ph-noe.ac.at/fileadmin/Mathematik_Uploads/ACDCA/ DESTIME2006/DES_contribs/Fu/simplification.pdf """ fRL1 = greedy(RL1, measure) fRL2 = greedy(RL2, measure) was = rv rv = sympify(rv) if not isinstance(rv, Expr): return rv.func([fu(a, measure=measure) for a in rv.args]) rv = TR1(rv) if rv.has(tan, cot): rv1 = fRL1(rv) if (measure(rv1) < measure(rv)): rv = rv1 if rv.has(tan, cot): rv = TR2(rv) if rv.has(sin, cos): rv1 = fRL2(rv) rv2 = TR8(TRmorrie(rv1)) rv = min([was, rv, rv1, rv2], key=measure) return min(TR2i(rv), rv, key=measure) def process_common_addends(rv, do, key2=None, key1=True): """Apply ``do`` to addends of ``rv`` that (if key1=True) share at least a common absolute value of their coefficient and the value of ``key2`` when applied to the argument. If ``key1`` is False ``key2`` must be supplied and will be the only key applied. """ # collect by absolute value of coefficient and key2 absc = defaultdict(list) if key1: for a in rv.args: c, a = a.as_coeff_Mul() if c < 0: c = -c a = -a # put the sign on `a` absc[(c, key2(a) if key2 else 1)].append(a) elif key2: for a in rv.args: absc[(S.One, key2(a))].append(a) else: raise ValueError('must have at least one key') args = [] hit = False for k in absc: v = absc[k] c, _ = k if len(v) > 1: e = Add(v, evaluate=False) new = do(e) if new != e: e = new hit = True args.append(ce) else: args.append(cv[0]) if hit: rv = Add(args) return rv fufuncs = ''' TR0 TR1 TR2 TR3 TR4 TR5 TR6 TR7 TR8 TR9 TR10 TR10i TR11 TR12 TR13 L TR2i TRmorrie TR12i TR14 TR15 TR16 TR111 TR22'''.split() FU = dict(list(zip(fufuncs, list(map(locals().get, fufuncs))))) def _roots(): global _ROOT2, _ROOT3, _invROOT3 _ROOT2, _ROOT3 = sqrt(2), sqrt(3) _invROOT3 = 1/_ROOT3 _ROOT2 = None def trig_split(a, b, two=False): """Return the gcd, s1, s2, a1, a2, bool where If two is False (default) then:: a + b = gcd(s1f(a1) + s2f(a2)) where f = cos if bool else sin else: if bool, a + b was +/- cos(a1)cos(a2) +/- sin(a1)sin(a2) and equals n1gcdcos(a - b) if n1 == n2 else n1gcdcos(a + b) else a + b was +/- cos(a1)sin(a2) +/- sin(a1)cos(a2) and equals n1gcdsin(a + b) if n1 = n2 else n1gcdsin(b - a) Examples ======== >>> from sympy.simplify.fu import trig_split >>> from sympy.abc import x, y, z >>> from sympy import cos, sin, sqrt >>> trig_split(cos(x), cos(y)) (1, 1, 1, x, y, True) >>> trig_split(2cos(x), -2cos(y)) (2, 1, -1, x, y, True) >>> trig_split(cos(x)sin(y), cos(y)sin(y)) (sin(y), 1, 1, x, y, True) >>> trig_split(cos(x), -sqrt(3)sin(x), two=True) (2, 1, -1, x, pi/6, False) >>> trig_split(cos(x), sin(x), two=True) (sqrt(2), 1, 1, x, pi/4, False) >>> trig_split(cos(x), -sin(x), two=True) (sqrt(2), 1, -1, x, pi/4, False) >>> trig_split(sqrt(2)cos(x), -sqrt(6)sin(x), two=True) (2sqrt(2), 1, -1, x, pi/6, False) >>> trig_split(-sqrt(6)cos(x), -sqrt(2)sin(x), two=True) (-2sqrt(2), 1, 1, x, pi/3, False) >>> trig_split(cos(x)/sqrt(6), sin(x)/sqrt(2), two=True) (sqrt(6)/3, 1, 1, x, pi/6, False) >>> trig_split(-sqrt(6)cos(x)sin(y), -sqrt(2)sin(x)sin(y), two=True) (-2sqrt(2)sin(y), 1, 1, x, pi/3, False) >>> trig_split(cos(x), sin(x)) >>> trig_split(cos(x), sin(z)) >>> trig_split(2cos(x), -sin(x)) >>> trig_split(cos(x), -sqrt(3)sin(x)) >>> trig_split(cos(x)cos(y), sin(x)sin(z)) >>> trig_split(cos(x)cos(y), sin(x)sin(y)) >>> trig_split(-sqrt(6)cos(x), sqrt(2)sin(x)sin(y), two=True) """ global _ROOT2, _ROOT3, _invROOT3 if _ROOT2 is None: _roots() a, b = [Factors(i) for i in (a, b)] ua, ub = a.normal(b) gcd = a.gcd(b).as_expr() n1 = n2 = 1 if S.NegativeOne in ua.factors: ua = ua.quo(S.NegativeOne) n1 = -n1 elif S.NegativeOne in ub.factors: ub = ub.quo(S.NegativeOne) n2 = -n2 a, b = [i.as_expr() for i in (ua, ub)] def pow_cos_sin(a, two): """Return ``a`` as a tuple (r, c, s) such that ``a = (r or 1)(c or 1)(s or 1)``. Three arguments are returned (radical, c-factor, s-factor) as long as the conditions set by ``two`` are met; otherwise None is returned. If ``two`` is True there will be one or two non-None values in the tuple: c and s or c and r or s and r or s or c with c being a cosine function (if possible) else a sine, and s being a sine function (if possible) else oosine. If ``two`` is False then there will only be a c or s term in the tuple. ``two`` also require that either two cos and/or sin be present (with the condition that if the functions are the same the arguments are different or vice versa) or that a single cosine or a single sine be present with an optional radical. If the above conditions dictated by ``two`` are not met then None is returned. """ c = s = None co = S.One if a.is_Mul: co, a = a.as_coeff_Mul() if len(a.args) > 2 or not two: return None if a.is_Mul: args = list(a.args) else: args = [a] a = args.pop(0) if isinstance(a, cos): c = a elif isinstance(a, sin): s = a elif a.is_Pow and a.exp is S.Half: # autoeval doesn't allow -1/2 co = a else: return None if args: b = args[0] if isinstance(b, cos): if c: s = b else: c = b elif isinstance(b, sin): if s: c = b else: s = b elif b.is_Pow and b.exp is S.Half: co = b else: return None return co if co is not S.One else None, c, s elif isinstance(a, cos): c = a elif isinstance(a, sin): s = a if c is None and s is None: return co = co if co is not S.One else None return co, c, s # get the parts m = pow_cos_sin(a, two) if m is None: return coa, ca, sa = m m = pow_cos_sin(b, two) if m is None: return cob, cb, sb = m # check them if (not ca) and cb or ca and isinstance(ca, sin): coa, ca, sa, cob, cb, sb = cob, cb, sb, coa, ca, sa n1, n2 = n2, n1 if not two: # need cos(x) and cos(y) or sin(x) and sin(y) c = ca or sa s = cb or sb if not isinstance(c, s.func): return None return gcd, n1, n2, c.args[0], s.args[0], isinstance(c, cos) else: if not coa and not cob: if (ca and cb and sa and sb): if isinstance(ca, sa.func) is not isinstance(cb, sb.func): return args = {j.args for j in (ca, sa)} if not all(i.args in args for i in (cb, sb)): return return gcd, n1, n2, ca.args[0], sa.args[0], isinstance(ca, sa.func) if ca and sa or cb and sb or \ two and (ca is None and sa is None or cb is None and sb is None): return c = ca or sa s = cb or sb if c.args != s.args: return if not coa: coa = S.One if not cob: cob = S.One if coa is cob: gcd = _ROOT2 return gcd, n1, n2, c.args[0], pi/4, False elif coa/cob == _ROOT3: gcd = 2cob return gcd, n1, n2, c.args[0], pi/3, False elif coa/cob == _invROOT3: gcd = 2coa return gcd, n1, n2, c.args[0], pi/6, False def as_f_sign_1(e): """If ``e`` is a sum that can be written as ``g(a + s)`` where ``s`` is ``+/-1``, return ``g``, ``a``, and ``s`` where ``a`` does not have a leading negative coefficient. Examples ======== >>> from sympy.simplify.fu import as_f_sign_1 >>> from sympy.abc import x >>> as_f_sign_1(x + 1) (1, x, 1) >>> as_f_sign_1(x - 1) (1, x, -1) >>> as_f_sign_1(-x + 1) (-1, x, -1) >>> as_f_sign_1(-x - 1) (-1, x, 1) >>> as_f_sign_1(2x + 2) (2, x, 1) """ if not e.is_Add or len(e.args) != 2: return # exact match a, b = e.args if a in (S.NegativeOne, S.One): g = S.One if b.is_Mul and b.args[0].is_Number and b.args[0] < 0: a, b = -a, -b g = -g return g, b, a # gcd match a, b = [Factors(i) for i in e.args] ua, ub = a.normal(b) gcd = a.gcd(b).as_expr() if S.NegativeOne in ua.factors: ua = ua.quo(S.NegativeOne) n1 = -1 n2 = 1 elif S.NegativeOne in ub.factors: ub = ub.quo(S.NegativeOne) n1 = 1 n2 = -1 else: n1 = n2 = 1 a, b = [i.as_expr() for i in (ua, ub)] if a is S.One: a, b = b, a n1, n2 = n2, n1 if n1 == -1: gcd = -gcd n2 = -n2 if b is S.One: return gcd, a, n2 def _osborne(e, d): """Replace all hyperbolic functions with trig functions using the Osborne rule. Notes ===== ``d`` is a dummy variable to prevent automatic evaluation of trigonometric/hyperbolic functions. References ========== https://en.wikipedia.org/wiki/Hyperbolic_function """ def f(rv): if not isinstance(rv, HyperbolicFunction): return rv a = rv.args[0] a = ad if not a.is_Add else Add._from_args([id for i in a.args]) if isinstance(rv, sinh): return Isin(a) elif isinstance(rv, cosh): return cos(a) elif isinstance(rv, tanh): return Itan(a) elif isinstance(rv, coth): return cot(a)/I elif isinstance(rv, sech): return sec(a) elif isinstance(rv, csch): return csc(a)/I else: raise NotImplementedError('unhandled %s' % rv.func) return bottom_up(e, f) def _osbornei(e, d): """Replace all trig functions with hyperbolic functions using the Osborne rule. Notes ===== ``d`` is a dummy variable to prevent automatic evaluation of trigonometric/hyperbolic functions. References ========== https://en.wikipedia.org/wiki/Hyperbolic_function """ def f(rv): if not isinstance(rv, TrigonometricFunction): return rv const, x = rv.args[0].as_independent(d, as_Add=True) a = x.xreplace({d: S.One}) + constI if isinstance(rv, sin): return sinh(a)/I elif isinstance(rv, cos): return cosh(a) elif isinstance(rv, tan): return tanh(a)/I elif isinstance(rv, cot): return coth(a)I elif isinstance(rv, sec): return sech(a) elif isinstance(rv, csc): return csch(a)I else: raise NotImplementedError('unhandled %s' % rv.func) return bottom_up(e, f) def hyper_as_trig(rv): """Return an expression containing hyperbolic functions in terms of trigonometric functions. Any trigonometric functions initially present are replaced with Dummy symbols and the function to undo the masking and the conversion back to hyperbolics is also returned. It should always be true that:: t, f = hyper_as_trig(expr) expr == f(t) Examples ======== >>> from sympy.simplify.fu import hyper_as_trig, fu >>> from sympy.abc import x >>> from sympy import cosh, sinh >>> eq = sinh(x)2 + cosh(x)2 >>> t, f = hyper_as_trig(eq) >>> f(fu(t)) cosh(2x) References ========== https://en.wikipedia.org/wiki/Hyperbolic_function """ from sympy.simplify.simplify import signsimp from sympy.simplify.radsimp import collect # mask off trig functions trigs = rv.atoms(TrigonometricFunction) reps = [(t, Dummy()) for t in trigs] masked = rv.xreplace(dict(reps)) # get inversion substitutions in place reps = [(v, k) for k, v in reps] d = Dummy() return _osborne(masked, d), lambda x: collect(signsimp( _osbornei(x, d).xreplace(dict(reps))), S.ImaginaryUnit) def sincos_to_sum(expr): """Convert products and powers of sin and cos to sums. Applied power reduction TRpower first, then expands products, and converts products to sums with TR8. Examples ======== >>> from sympy.simplify.fu import sincos_to_sum >>> from sympy.abc import x >>> from sympy import cos, sin >>> sincos_to_sum(16sin(x)*3cos(2x)2) 7sin(x) - 5sin(3x) + 3sin(5x) - sin(7*x) """ if not expr.has(cos, sin): return expr else: return TR8(expand_mul(TRpower(expr)))
8cf9903b7dd9c2411d5ccdd227670828e59b51dca7f208383ba67e198ea32366	""" This module cooks up a docstring when imported. Its only purpose is to be displayed in the sphinx documentation. """ from __future__ import print_function, division from sympy import latex, Eq, hyper from sympy.simplify.hyperexpand import FormulaCollection c = FormulaCollection() doc = "" for f in c.formulae: obj = Eq(hyper(f.func.ap, f.func.bq, f.z), f.closed_form.rewrite('nonrepsmall')) doc += ".. math::\n %s\n" % latex(obj) __doc__ = doc
977e80bdd1b09ed4c19fa01479b35b83a73a6af335cf471fe559b59ad83270aa	from __future__ import print_function, division from itertools import combinations_with_replacement from sympy.core import symbols, Add, Dummy from sympy.core.numbers import Rational from sympy.polys import cancel, ComputationFailed, parallel_poly_from_expr, reduced, Poly from sympy.polys.monomials import Monomial, monomial_div from sympy.polys.polyerrors import DomainError, PolificationFailed from sympy.utilities.misc import debug def ratsimp(expr): """ Put an expression over a common denominator, cancel and reduce. Examples ======== >>> from sympy import ratsimp >>> from sympy.abc import x, y >>> ratsimp(1/x + 1/y) (x + y)/(xy) """ f, g = cancel(expr).as_numer_denom() try: Q, r = reduced(f, [g], field=True, expand=False) except ComputationFailed: return f/g return Add(Q) + cancel(r/g) def ratsimpmodprime(expr, G, gens, args): """ Simplifies a rational expression ``expr`` modulo the prime ideal generated by ``G``. ``G`` should be a Groebner basis of the ideal. >>> from sympy.simplify.ratsimp import ratsimpmodprime >>> from sympy.abc import x, y >>> eq = (x + y5 + y)/(x - y) >>> ratsimpmodprime(eq, [xy5 - x - y], x, y, order='lex') (x2 + xy + x + y)/(x2 - xy) If ``polynomial`` is False, the algorithm computes a rational simplification which minimizes the sum of the total degrees of the numerator and the denominator. If ``polynomial`` is True, this function just brings numerator and denominator into a canonical form. This is much faster, but has potentially worse results. References ========== .. [1] M. Monagan, R. Pearce, Rational Simplification Modulo a Polynomial Ideal, http://citeseer.ist.psu.edu/viewdoc/summary?doi=10.1.1.163.6984 (specifically, the second algorithm) """ from sympy import solve quick = args.pop('quick', True) polynomial = args.pop('polynomial', False) debug('ratsimpmodprime', expr) # usual preparation of polynomials: num, denom = cancel(expr).as_numer_denom() try: polys, opt = parallel_poly_from_expr([num, denom] + G, gens, args) except PolificationFailed: return expr domain = opt.domain if domain.has_assoc_Field: opt.domain = domain.get_field() else: raise DomainError( "can't compute rational simplification over %s" % domain) # compute only once leading_monomials = [g.LM(opt.order) for g in polys[2:]] tested = set() def staircase(n): """ Compute all monomials with degree less than ``n`` that are not divisible by any element of ``leading_monomials``. """ if n == 0: return [1] S = [] for mi in combinations_with_replacement(range(len(opt.gens)), n): m = [0]len(opt.gens) for i in mi: m[i] += 1 if all([monomial_div(m, lmg) is None for lmg in leading_monomials]): S.append(m) return [Monomial(s).as_expr(opt.gens) for s in S] + staircase(n - 1) def _ratsimpmodprime(a, b, allsol, N=0, D=0): r""" Computes a rational simplification of ``a/b`` which minimizes the sum of the total degrees of the numerator and the denominator. The algorithm proceeds by looking at ``a d - b * c`` modulo the ideal generated by ``G`` for some ``c`` and ``d`` with degree less than ``a`` and ``b`` respectively. The coefficients of ``c`` and ``d`` are indeterminates and thus the coefficients of the normalform of ``a * d - b * c`` are linear polynomials in these indeterminates. If these linear polynomials, considered as system of equations, have a nontrivial solution, then `\frac{a}{b} \equiv \frac{c}{d}` modulo the ideal generated by ``G``. So, by construction, the degree of ``c`` and ``d`` is less than the degree of ``a`` and ``b``, so a simpler representation has been found. After a simpler representation has been found, the algorithm tries to reduce the degree of the numerator and denominator and returns the result afterwards. As an extension, if quick=False, we look at all possible degrees such that the total degree is less than or equal to the best current solution. We retain a list of all solutions of minimal degree, and try to find the best one at the end. """ c, d = a, b steps = 0 maxdeg = a.total_degree() + b.total_degree() if quick: bound = maxdeg - 1 else: bound = maxdeg while N + D <= bound: if (N, D) in tested: break tested.add((N, D)) M1 = staircase(N) M2 = staircase(D) debug('%s / %s: %s, %s' % (N, D, M1, M2)) Cs = symbols("c:%d" % len(M1), cls=Dummy) Ds = symbols("d:%d" % len(M2), cls=Dummy) ng = Cs + Ds c_hat = Poly( sum([Cs[i] * M1[i] for i in range(len(M1))]), opt.gens + ng) d_hat = Poly( sum([Ds[i] * M2[i] for i in range(len(M2))]), opt.gens + ng) r = reduced(a * d_hat - b * c_hat, G, opt.gens + ng, order=opt.order, polys=True)[1] S = Poly(r, gens=opt.gens).coeffs() sol = solve(S, Cs + Ds, particular=True, quick=True) if sol and not all([s == 0 for s in sol.values()]): c = c_hat.subs(sol) d = d_hat.subs(sol) # The "free" variables occurring before as parameters # might still be in the substituted c, d, so set them # to the value chosen before: c = c.subs(dict(list(zip(Cs + Ds, [1] * (len(Cs) + len(Ds)))))) d = d.subs(dict(list(zip(Cs + Ds, [1] * (len(Cs) + len(Ds)))))) c = Poly(c, opt.gens) d = Poly(d, opt.gens) if d == 0: raise ValueError('Ideal not prime?') allsol.append((c_hat, d_hat, S, Cs + Ds)) if N + D != maxdeg: allsol = [allsol[-1]] break steps += 1 N += 1 D += 1 if steps > 0: c, d, allsol = _ratsimpmodprime(c, d, allsol, N, D - steps) c, d, allsol = _ratsimpmodprime(c, d, allsol, N - steps, D) return c, d, allsol # preprocessing. this improves performance a bit when deg(num) # and deg(denom) are large: num = reduced(num, G, opt.gens, order=opt.order)[1] denom = reduced(denom, G, opt.gens, order=opt.order)[1] if polynomial: return (num/denom).cancel() c, d, allsol = _ratsimpmodprime( Poly(num, opt.gens, domain=opt.domain), Poly(denom, opt.gens, domain=opt.domain), []) if not quick and allsol: debug('Looking for best minimal solution. Got: %s' % len(allsol)) newsol = [] for c_hat, d_hat, S, ng in allsol: sol = solve(S, ng, particular=True, quick=False) newsol.append((c_hat.subs(sol), d_hat.subs(sol))) c, d = min(newsol, key=lambda x: len(x[0].terms()) + len(x[1].terms())) if not domain.is_Field: cn, c = c.clear_denoms(convert=True) dn, d = d.clear_denoms(convert=True) r = Rational(cn, dn) else: r = Rational(1) return (cr.q)/(dr.p)
7a8345040ea0ebbeb24b551356d303757f684ba87cdfabc7ce64fc81ad571c74	r""" This module contains :py:meth:`~sympy.solvers.ode.dsolve` and different helper functions that it uses. :py:meth:`~sympy.solvers.ode.dsolve` solves ordinary differential equations. See the docstring on the various functions for their uses. Note that partial differential equations support is in ``pde.py``. Note that hint functions have docstrings describing their various methods, but they are intended for internal use. Use ``dsolve(ode, func, hint=hint)`` to solve an ODE using a specific hint. See also the docstring on :py:meth:`~sympy.solvers.ode.dsolve`. Functions in this module These are the user functions in this module: - :py:meth:`~sympy.solvers.ode.dsolve` - Solves ODEs. - :py:meth:`~sympy.solvers.ode.classify_ode` - Classifies ODEs into possible hints for :py:meth:`~sympy.solvers.ode.dsolve`. - :py:meth:`~sympy.solvers.ode.checkodesol` - Checks if an equation is the solution to an ODE. - :py:meth:`~sympy.solvers.ode.homogeneous_order` - Returns the homogeneous order of an expression. - :py:meth:`~sympy.solvers.ode.infinitesimals` - Returns the infinitesimals of the Lie group of point transformations of an ODE, such that it is invariant. - :py:meth:`~sympy.solvers.ode_checkinfsol` - Checks if the given infinitesimals are the actual infinitesimals of a first order ODE. These are the non-solver helper functions that are for internal use. The user should use the various options to :py:meth:`~sympy.solvers.ode.dsolve` to obtain the functionality provided by these functions: - :py:meth:`~sympy.solvers.ode.odesimp` - Does all forms of ODE simplification. - :py:meth:`~sympy.solvers.ode.ode_sol_simplicity` - A key function for comparing solutions by simplicity. - :py:meth:`~sympy.solvers.ode.constantsimp` - Simplifies arbitrary constants. - :py:meth:`~sympy.solvers.ode.constant_renumber` - Renumber arbitrary constants. - :py:meth:`~sympy.solvers.ode._handle_Integral` - Evaluate unevaluated Integrals. See also the docstrings of these functions. Currently implemented solver methods The following methods are implemented for solving ordinary differential equations. See the docstrings of the various hint functions for more information on each (run ``help(ode)``): - 1st order separable differential equations. - 1st order differential equations whose coefficients or `dx` and `dy` are functions homogeneous of the same order. - 1st order exact differential equations. - 1st order linear differential equations. - 1st order Bernoulli differential equations. - Power series solutions for first order differential equations. - Lie Group method of solving first order differential equations. - 2nd order Liouville differential equations. - Power series solutions for second order differential equations at ordinary and regular singular points. - `n`\th order differential equation that can be solved with algebraic rearrangement and integration. - `n`\th order linear homogeneous differential equation with constant coefficients. - `n`\th order linear inhomogeneous differential equation with constant coefficients using the method of undetermined coefficients. - `n`\th order linear inhomogeneous differential equation with constant coefficients using the method of variation of parameters. Philosophy behind this module This module is designed to make it easy to add new ODE solving methods without having to mess with the solving code for other methods. The idea is that there is a :py:meth:`~sympy.solvers.ode.classify_ode` function, which takes in an ODE and tells you what hints, if any, will solve the ODE. It does this without attempting to solve the ODE, so it is fast. Each solving method is a hint, and it has its own function, named ``ode_<hint>``. That function takes in the ODE and any match expression gathered by :py:meth:`~sympy.solvers.ode.classify_ode` and returns a solved result. If this result has any integrals in it, the hint function will return an unevaluated :py:class:`~sympy.integrals.Integral` class. :py:meth:`~sympy.solvers.ode.dsolve`, which is the user wrapper function around all of this, will then call :py:meth:`~sympy.solvers.ode.odesimp` on the result, which, among other things, will attempt to solve the equation for the dependent variable (the function we are solving for), simplify the arbitrary constants in the expression, and evaluate any integrals, if the hint allows it. How to add new solution methods If you have an ODE that you want :py:meth:`~sympy.solvers.ode.dsolve` to be able to solve, try to avoid adding special case code here. Instead, try finding a general method that will solve your ODE, as well as others. This way, the :py:mod:`~sympy.solvers.ode` module will become more robust, and unhindered by special case hacks. WolphramAlpha and Maple's DETools[odeadvisor] function are two resources you can use to classify a specific ODE. It is also better for a method to work with an `n`\th order ODE instead of only with specific orders, if possible. To add a new method, there are a few things that you need to do. First, you need a hint name for your method. Try to name your hint so that it is unambiguous with all other methods, including ones that may not be implemented yet. If your method uses integrals, also include a ``hint_Integral`` hint. If there is more than one way to solve ODEs with your method, include a hint for each one, as well as a ``<hint>_best`` hint. Your ``ode_<hint>_best()`` function should choose the best using min with ``ode_sol_simplicity`` as the key argument. See :py:meth:`~sympy.solvers.ode.ode_1st_homogeneous_coeff_best`, for example. The function that uses your method will be called ``ode_<hint>()``, so the hint must only use characters that are allowed in a Python function name (alphanumeric characters and the underscore '``_``' character). Include a function for every hint, except for ``_Integral`` hints (:py:meth:`~sympy.solvers.ode.dsolve` takes care of those automatically). Hint names should be all lowercase, unless a word is commonly capitalized (such as Integral or Bernoulli). If you have a hint that you do not want to run with ``all_Integral`` that doesn't have an ``_Integral`` counterpart (such as a best hint that would defeat the purpose of ``all_Integral``), you will need to remove it manually in the :py:meth:`~sympy.solvers.ode.dsolve` code. See also the :py:meth:`~sympy.solvers.ode.classify_ode` docstring for guidelines on writing a hint name. Determine in general how the solutions returned by your method compare with other methods that can potentially solve the same ODEs. Then, put your hints in the :py:data:`~sympy.solvers.ode.allhints` tuple in the order that they should be called. The ordering of this tuple determines which hints are default. Note that exceptions are ok, because it is easy for the user to choose individual hints with :py:meth:`~sympy.solvers.ode.dsolve`. In general, ``_Integral`` variants should go at the end of the list, and ``_best`` variants should go before the various hints they apply to. For example, the ``undetermined_coefficients`` hint comes before the ``variation_of_parameters`` hint because, even though variation of parameters is more general than undetermined coefficients, undetermined coefficients generally returns cleaner results for the ODEs that it can solve than variation of parameters does, and it does not require integration, so it is much faster. Next, you need to have a match expression or a function that matches the type of the ODE, which you should put in :py:meth:`~sympy.solvers.ode.classify_ode` (if the match function is more than just a few lines, like :py:meth:`~sympy.solvers.ode._undetermined_coefficients_match`, it should go outside of :py:meth:`~sympy.solvers.ode.classify_ode`). It should match the ODE without solving for it as much as possible, so that :py:meth:`~sympy.solvers.ode.classify_ode` remains fast and is not hindered by bugs in solving code. Be sure to consider corner cases. For example, if your solution method involves dividing by something, make sure you exclude the case where that division will be 0. In most cases, the matching of the ODE will also give you the various parts that you need to solve it. You should put that in a dictionary (``.match()`` will do this for you), and add that as ``matching_hints['hint'] = matchdict`` in the relevant part of :py:meth:`~sympy.solvers.ode.classify_ode`. :py:meth:`~sympy.solvers.ode.classify_ode` will then send this to :py:meth:`~sympy.solvers.ode.dsolve`, which will send it to your function as the ``match`` argument. Your function should be named ``ode_<hint>(eq, func, order, match)`. If you need to send more information, put it in the ``match`` dictionary. For example, if you had to substitute in a dummy variable in :py:meth:`~sympy.solvers.ode.classify_ode` to match the ODE, you will need to pass it to your function using the `match` dict to access it. You can access the independent variable using ``func.args[0]``, and the dependent variable (the function you are trying to solve for) as ``func.func``. If, while trying to solve the ODE, you find that you cannot, raise ``NotImplementedError``. :py:meth:`~sympy.solvers.ode.dsolve` will catch this error with the ``all`` meta-hint, rather than causing the whole routine to fail. Add a docstring to your function that describes the method employed. Like with anything else in SymPy, you will need to add a doctest to the docstring, in addition to real tests in ``test_ode.py``. Try to maintain consistency with the other hint functions' docstrings. Add your method to the list at the top of this docstring. Also, add your method to ``ode.rst`` in the ``docs/src`` directory, so that the Sphinx docs will pull its docstring into the main SymPy documentation. Be sure to make the Sphinx documentation by running ``make html`` from within the doc directory to verify that the docstring formats correctly. If your solution method involves integrating, use :py:meth:`Integral() <sympy.integrals.integrals.Integral>` instead of :py:meth:`~sympy.core.expr.Expr.integrate`. This allows the user to bypass hard/slow integration by using the ``_Integral`` variant of your hint. In most cases, calling :py:meth:`sympy.core.basic.Basic.doit` will integrate your solution. If this is not the case, you will need to write special code in :py:meth:`~sympy.solvers.ode._handle_Integral`. Arbitrary constants should be symbols named ``C1``, ``C2``, and so on. All solution methods should return an equality instance. If you need an arbitrary number of arbitrary constants, you can use ``constants = numbered_symbols(prefix='C', cls=Symbol, start=1)``. If it is possible to solve for the dependent function in a general way, do so. Otherwise, do as best as you can, but do not call solve in your ``ode_<hint>()`` function. :py:meth:`~sympy.solvers.ode.odesimp` will attempt to solve the solution for you, so you do not need to do that. Lastly, if your ODE has a common simplification that can be applied to your solutions, you can add a special case in :py:meth:`~sympy.solvers.ode.odesimp` for it. For example, solutions returned from the ``1st_homogeneous_coeff`` hints often have many :py:meth:`~sympy.functions.log` terms, so :py:meth:`~sympy.solvers.ode.odesimp` calls :py:meth:`~sympy.simplify.simplify.logcombine` on them (it also helps to write the arbitrary constant as ``log(C1)`` instead of ``C1`` in this case). Also consider common ways that you can rearrange your solution to have :py:meth:`~sympy.solvers.ode.constantsimp` take better advantage of it. It is better to put simplification in :py:meth:`~sympy.solvers.ode.odesimp` than in your method, because it can then be turned off with the simplify flag in :py:meth:`~sympy.solvers.ode.dsolve`. If you have any extraneous simplification in your function, be sure to only run it using ``if match.get('simplify', True):``, especially if it can be slow or if it can reduce the domain of the solution. Finally, as with every contribution to SymPy, your method will need to be tested. Add a test for each method in ``test_ode.py``. Follow the conventions there, i.e., test the solver using ``dsolve(eq, f(x), hint=your_hint)``, and also test the solution using :py:meth:`~sympy.solvers.ode.checkodesol` (you can put these in a separate tests and skip/XFAIL if it runs too slow/doesn't work). Be sure to call your hint specifically in :py:meth:`~sympy.solvers.ode.dsolve`, that way the test won't be broken simply by the introduction of another matching hint. If your method works for higher order (>1) ODEs, you will need to run ``sol = constant_renumber(sol, 'C', 1, order)`` for each solution, where ``order`` is the order of the ODE. This is because ``constant_renumber`` renumbers the arbitrary constants by printing order, which is platform dependent. Try to test every corner case of your solver, including a range of orders if it is a `n`\th order solver, but if your solver is slow, such as if it involves hard integration, try to keep the test run time down. Feel free to refactor existing hints to avoid duplicating code or creating inconsistencies. If you can show that your method exactly duplicates an existing method, including in the simplicity and speed of obtaining the solutions, then you can remove the old, less general method. The existing code is tested extensively in ``test_ode.py``, so if anything is broken, one of those tests will surely fail. """ from __future__ import print_function, division from collections import defaultdict from itertools import islice from functools import cmp_to_key from sympy.core import Add, S, Mul, Pow, oo from sympy.core.compatibility import ordered, iterable, is_sequence, range from sympy.core.containers import Tuple from sympy.core.exprtools import factor_terms from sympy.core.expr import AtomicExpr, Expr from sympy.core.function import (Function, Derivative, AppliedUndef, diff, expand, expand_mul, Subs, _mexpand) from sympy.core.multidimensional import vectorize from sympy.core.numbers import NaN, zoo, I, Number from sympy.core.relational import Equality, Eq from sympy.core.symbol import Symbol, Wild, Dummy, symbols from sympy.core.sympify import sympify from sympy.logic.boolalg import (BooleanAtom, And, Or, Not, BooleanTrue, BooleanFalse) from sympy.functions import cos, exp, im, log, re, sin, tan, sqrt, \ atan2, conjugate, Piecewise from sympy.functions.combinatorial.factorials import factorial from sympy.integrals.integrals import Integral, integrate from sympy.matrices import wronskian, Matrix, eye, zeros from sympy.polys import (Poly, RootOf, rootof, terms_gcd, PolynomialError, lcm, roots) from sympy.polys.polyroots import roots_quartic from sympy.polys.polytools import cancel, degree, div from sympy.series import Order from sympy.series.series import series from sympy.simplify import collect, logcombine, powsimp, separatevars, \ simplify, trigsimp, denom, posify, cse from sympy.simplify.powsimp import powdenest from sympy.simplify.radsimp import collect_const from sympy.solvers import solve from sympy.solvers.pde import pdsolve from sympy.utilities import numbered_symbols, default_sort_key, sift from sympy.solvers.deutils import _preprocess, ode_order, _desolve #: This is a list of hints in the order that they should be preferred by #: :py:meth:`~sympy.solvers.ode.classify_ode`. In general, hints earlier in the #: list should produce simpler solutions than those later in the list (for #: ODEs that fit both). For now, the order of this list is based on empirical #: observations by the developers of SymPy. #: #: The hint used by :py:meth:`~sympy.solvers.ode.dsolve` for a specific ODE #: can be overridden (see the docstring). #: #: In general, ``_Integral`` hints are grouped at the end of the list, unless #: there is a method that returns an unevaluable integral most of the time #: (which go near the end of the list anyway). ``default``, ``all``, #: ``best``, and ``all_Integral`` meta-hints should not be included in this #: list, but ``_best`` and ``_Integral`` hints should be included. allhints = ( "nth_algebraic", "separable", "1st_exact", "1st_linear", "Bernoulli", "Riccati_special_minus2", "1st_homogeneous_coeff_best", "1st_homogeneous_coeff_subs_indep_div_dep", "1st_homogeneous_coeff_subs_dep_div_indep", "almost_linear", "linear_coefficients", "separable_reduced", "1st_power_series", "lie_group", "nth_linear_constant_coeff_homogeneous", "nth_linear_euler_eq_homogeneous", "nth_linear_constant_coeff_undetermined_coefficients", "nth_linear_euler_eq_nonhomogeneous_undetermined_coefficients", "nth_linear_constant_coeff_variation_of_parameters", "nth_linear_euler_eq_nonhomogeneous_variation_of_parameters", "Liouville", "2nd_power_series_ordinary", "2nd_power_series_regular", "nth_algebraic_Integral", "separable_Integral", "1st_exact_Integral", "1st_linear_Integral", "Bernoulli_Integral", "1st_homogeneous_coeff_subs_indep_div_dep_Integral", "1st_homogeneous_coeff_subs_dep_div_indep_Integral", "almost_linear_Integral", "linear_coefficients_Integral", "separable_reduced_Integral", "nth_linear_constant_coeff_variation_of_parameters_Integral", "nth_linear_euler_eq_nonhomogeneous_variation_of_parameters_Integral", "Liouville_Integral", ) lie_heuristics = ( "abaco1_simple", "abaco1_product", "abaco2_similar", "abaco2_unique_unknown", "abaco2_unique_general", "linear", "function_sum", "bivariate", "chi" ) def sub_func_doit(eq, func, new): r""" When replacing the func with something else, we usually want the derivative evaluated, so this function helps in making that happen. To keep subs from having to look through all derivatives, we mask them off with dummy variables, do the func sub, and then replace masked-off derivatives with their doit values. Examples ======== >>> from sympy import Derivative, symbols, Function >>> from sympy.solvers.ode import sub_func_doit >>> x, z = symbols('x, z') >>> y = Function('y') >>> sub_func_doit(3Derivative(y(x), x) - 1, y(x), x) 2 >>> sub_func_doit(xDerivative(y(x), x) - y(x)*2 + y(x), y(x), ... 1/(x(z + 1/x))) x(-1/(x2(z + 1/x)) + 1/(x*3(z + 1/x)*2)) + 1/(x(z + 1/x)) ...- 1/(x*2(z + 1/x)*2) """ reps = {} repu = {} for d in eq.atoms(Derivative): u = Dummy('u') repu[u] = d.subs(func, new).doit() reps[d] = u # Make sure that expressions such as ``Derivative(f(x), (x, 2))`` get # replaced before ``Derivative(f(x), x)``: # # Also replace e.g. Derivative(xDerivative(f(x), x), x) before # Derivative(f(x), x) def cmp(subs1, subs2): return subs2[0].has(subs1[0]) - subs1[0].has(subs2[0]) key = lambda x: (-x[0].derivative_count, cmp_to_key(cmp)(x)) reps = sorted(reps.items(), key=key) return eq.subs(reps).subs(func, new).subs(repu) def get_numbered_constants(eq, num=1, start=1, prefix='C'): """ Returns a list of constants that do not occur in eq already. """ if isinstance(eq, Expr): eq = [eq] elif not iterable(eq): raise ValueError("Expected Expr or iterable but got %s" % eq) atom_set = set().union([i.free_symbols for i in eq]) func_set = set().union([i.atoms(Function) for i in eq]) if func_set: atom_set \|= {Symbol(str(f.func)) for f in func_set} ncs = numbered_symbols(start=start, prefix=prefix, exclude=atom_set) Cs = [next(ncs) for i in range(num)] return (Cs[0] if num == 1 else tuple(Cs)) def dsolve(eq, func=None, hint="default", simplify=True, ics= None, xi=None, eta=None, x0=0, n=6, kwargs): r""" Solves any (supported) kind of ordinary differential equation and system of ordinary differential equations. For single ordinary differential equation ========================================= It is classified under this when number of equation in ``eq`` is one. Usage ``dsolve(eq, f(x), hint)`` -> Solve ordinary differential equation ``eq`` for function ``f(x)``, using method ``hint``. Details ``eq`` can be any supported ordinary differential equation (see the :py:mod:`~sympy.solvers.ode` docstring for supported methods). This can either be an :py:class:`~sympy.core.relational.Equality`, or an expression, which is assumed to be equal to ``0``. ``f(x)`` is a function of one variable whose derivatives in that variable make up the ordinary differential equation ``eq``. In many cases it is not necessary to provide this; it will be autodetected (and an error raised if it couldn't be detected). ``hint`` is the solving method that you want dsolve to use. Use ``classify_ode(eq, f(x))`` to get all of the possible hints for an ODE. The default hint, ``default``, will use whatever hint is returned first by :py:meth:`~sympy.solvers.ode.classify_ode`. See Hints below for more options that you can use for hint. ``simplify`` enables simplification by :py:meth:`~sympy.solvers.ode.odesimp`. See its docstring for more information. Turn this off, for example, to disable solving of solutions for ``func`` or simplification of arbitrary constants. It will still integrate with this hint. Note that the solution may contain more arbitrary constants than the order of the ODE with this option enabled. ``xi`` and ``eta`` are the infinitesimal functions of an ordinary differential equation. They are the infinitesimals of the Lie group of point transformations for which the differential equation is invariant. The user can specify values for the infinitesimals. If nothing is specified, ``xi`` and ``eta`` are calculated using :py:meth:`~sympy.solvers.ode.infinitesimals` with the help of various heuristics. ``ics`` is the set of initial/boundary conditions for the differential equation. It should be given in the form of ``{f(x0): x1, f(x).diff(x).subs(x, x2): x3}`` and so on. For power series solutions, if no initial conditions are specified ``f(0)`` is assumed to be ``C0`` and the power series solution is calculated about 0. ``x0`` is the point about which the power series solution of a differential equation is to be evaluated. ``n`` gives the exponent of the dependent variable up to which the power series solution of a differential equation is to be evaluated. Hints Aside from the various solving methods, there are also some meta-hints that you can pass to :py:meth:`~sympy.solvers.ode.dsolve`: ``default``: This uses whatever hint is returned first by :py:meth:`~sympy.solvers.ode.classify_ode`. This is the default argument to :py:meth:`~sympy.solvers.ode.dsolve`. ``all``: To make :py:meth:`~sympy.solvers.ode.dsolve` apply all relevant classification hints, use ``dsolve(ODE, func, hint="all")``. This will return a dictionary of ``hint:solution`` terms. If a hint causes dsolve to raise the ``NotImplementedError``, value of that hint's key will be the exception object raised. The dictionary will also include some special keys: - ``order``: The order of the ODE. See also :py:meth:`~sympy.solvers.deutils.ode_order` in ``deutils.py``. - ``best``: The simplest hint; what would be returned by ``best`` below. - ``best_hint``: The hint that would produce the solution given by ``best``. If more than one hint produces the best solution, the first one in the tuple returned by :py:meth:`~sympy.solvers.ode.classify_ode` is chosen. - ``default``: The solution that would be returned by default. This is the one produced by the hint that appears first in the tuple returned by :py:meth:`~sympy.solvers.ode.classify_ode`. ``all_Integral``: This is the same as ``all``, except if a hint also has a corresponding ``_Integral`` hint, it only returns the ``_Integral`` hint. This is useful if ``all`` causes :py:meth:`~sympy.solvers.ode.dsolve` to hang because of a difficult or impossible integral. This meta-hint will also be much faster than ``all``, because :py:meth:`~sympy.core.expr.Expr.integrate` is an expensive routine. ``best``: To have :py:meth:`~sympy.solvers.ode.dsolve` try all methods and return the simplest one. This takes into account whether the solution is solvable in the function, whether it contains any Integral classes (i.e. unevaluatable integrals), and which one is the shortest in size. See also the :py:meth:`~sympy.solvers.ode.classify_ode` docstring for more info on hints, and the :py:mod:`~sympy.solvers.ode` docstring for a list of all supported hints. Tips - You can declare the derivative of an unknown function this way: >>> from sympy import Function, Derivative >>> from sympy.abc import x # x is the independent variable >>> f = Function("f")(x) # f is a function of x >>> # f_ will be the derivative of f with respect to x >>> f_ = Derivative(f, x) - See ``test_ode.py`` for many tests, which serves also as a set of examples for how to use :py:meth:`~sympy.solvers.ode.dsolve`. - :py:meth:`~sympy.solvers.ode.dsolve` always returns an :py:class:`~sympy.core.relational.Equality` class (except for the case when the hint is ``all`` or ``all_Integral``). If possible, it solves the solution explicitly for the function being solved for. Otherwise, it returns an implicit solution. - Arbitrary constants are symbols named ``C1``, ``C2``, and so on. - Because all solutions should be mathematically equivalent, some hints may return the exact same result for an ODE. Often, though, two different hints will return the same solution formatted differently. The two should be equivalent. Also note that sometimes the values of the arbitrary constants in two different solutions may not be the same, because one constant may have "absorbed" other constants into it. - Do ``help(ode.ode_<hintname>)`` to get help more information on a specific hint, where ``<hintname>`` is the name of a hint without ``_Integral``. For system of ordinary differential equations ============================================= Usage ``dsolve(eq, func)`` -> Solve a system of ordinary differential equations ``eq`` for ``func`` being list of functions including `x(t)`, `y(t)`, `z(t)` where number of functions in the list depends upon the number of equations provided in ``eq``. Details ``eq`` can be any supported system of ordinary differential equations This can either be an :py:class:`~sympy.core.relational.Equality`, or an expression, which is assumed to be equal to ``0``. ``func`` holds ``x(t)`` and ``y(t)`` being functions of one variable which together with some of their derivatives make up the system of ordinary differential equation ``eq``. It is not necessary to provide this; it will be autodetected (and an error raised if it couldn't be detected). Hints** The hints are formed by parameters returned by classify_sysode, combining them give hints name used later for forming method name. Examples ======== >>> from sympy import Function, dsolve, Eq, Derivative, sin, cos, symbols >>> from sympy.abc import x >>> f = Function('f') >>> dsolve(Derivative(f(x), x, x) + 9f(x), f(x)) Eq(f(x), C1sin(3x) + C2cos(3x)) >>> eq = sin(x)cos(f(x)) + cos(x)sin(f(x))f(x).diff(x) >>> dsolve(eq, hint='1st_exact') [Eq(f(x), -acos(C1/cos(x)) + 2pi), Eq(f(x), acos(C1/cos(x)))] >>> dsolve(eq, hint='almost_linear') [Eq(f(x), -acos(C1/cos(x)) + 2pi), Eq(f(x), acos(C1/cos(x)))] >>> t = symbols('t') >>> x, y = symbols('x, y', cls=Function) >>> eq = (Eq(Derivative(x(t),t), 12tx(t) + 8y(t)), Eq(Derivative(y(t),t), 21x(t) + 7ty(t))) >>> dsolve(eq) [Eq(x(t), C1x0(t) + C2x0(t)Integral(8exp(Integral(7t, t))exp(Integral(12t, t))/x0(t)2, t)), Eq(y(t), C1y0(t) + C2(y0(t)Integral(8exp(Integral(7t, t))exp(Integral(12t, t))/x0(t)*2, t) + exp(Integral(7t, t))exp(Integral(12t, t))/x0(t)))] >>> eq = (Eq(Derivative(x(t),t),x(t)y(t)sin(t)), Eq(Derivative(y(t),t),y(t)*2sin(t))) >>> dsolve(eq) {Eq(x(t), -exp(C1)/(C2exp(C1) - cos(t))), Eq(y(t), -1/(C1 - cos(t)))} """ if iterable(eq): match = classify_sysode(eq, func) eq = match['eq'] order = match['order'] func = match['func'] t = list(list(eq[0].atoms(Derivative))[0].atoms(Symbol))[0] # keep highest order term coefficient positive for i in range(len(eq)): for func_ in func: if isinstance(func_, list): pass else: if eq[i].coeff(diff(func[i],t,ode_order(eq[i], func[i]))).is_negative: eq[i] = -eq[i] match['eq'] = eq if len(set(order.values()))!=1: raise ValueError("It solves only those systems of equations whose orders are equal") match['order'] = list(order.values())[0] def recur_len(l): return sum(recur_len(item) if isinstance(item,list) else 1 for item in l) if recur_len(func) != len(eq): raise ValueError("dsolve() and classify_sysode() work with " "number of functions being equal to number of equations") if match['type_of_equation'] is None: raise NotImplementedError else: if match['is_linear'] == True: if match['no_of_equation'] > 3: solvefunc = globals()['sysode_linear_neq_order%(order)s' % match] else: solvefunc = globals()['sysode_linear_%(no_of_equation)seq_order%(order)s' % match] else: solvefunc = globals()['sysode_nonlinear_%(no_of_equation)seq_order%(order)s' % match] sols = solvefunc(match) if ics: constants = Tuple(sols).free_symbols - Tuple(eq).free_symbols solved_constants = solve_ics(sols, func, constants, ics) return [sol.subs(solved_constants) for sol in sols] return sols else: given_hint = hint # hint given by the user # See the docstring of _desolve for more details. hints = _desolve(eq, func=func, hint=hint, simplify=True, xi=xi, eta=eta, type='ode', ics=ics, x0=x0, n=n, kwargs) eq = hints.pop('eq', eq) all_ = hints.pop('all', False) if all_: retdict = {} failed_hints = {} gethints = classify_ode(eq, dict=True) orderedhints = gethints['ordered_hints'] for hint in hints: try: rv = _helper_simplify(eq, hint, hints[hint], simplify) except NotImplementedError as detail: failed_hints[hint] = detail else: retdict[hint] = rv func = hints[hint]['func'] retdict['best'] = min(list(retdict.values()), key=lambda x: ode_sol_simplicity(x, func, trysolving=not simplify)) if given_hint == 'best': return retdict['best'] for i in orderedhints: if retdict['best'] == retdict.get(i, None): retdict['best_hint'] = i break retdict['default'] = gethints['default'] retdict['order'] = gethints['order'] retdict.update(failed_hints) return retdict else: # The key 'hint' stores the hint needed to be solved for. hint = hints['hint'] return _helper_simplify(eq, hint, hints, simplify, ics=ics) def _helper_simplify(eq, hint, match, simplify=True, ics=None, kwargs): r""" Helper function of dsolve that calls the respective :py:mod:`~sympy.solvers.ode` functions to solve for the ordinary differential equations. This minimizes the computation in calling :py:meth:`~sympy.solvers.deutils._desolve` multiple times. """ r = match if hint.endswith('_Integral'): solvefunc = globals()['ode_' + hint[:-len('_Integral')]] else: solvefunc = globals()['ode_' + hint] func = r['func'] order = r['order'] match = r[hint] free = eq.free_symbols cons = lambda s: s.free_symbols.difference(free) if simplify: # odesimp() will attempt to integrate, if necessary, apply constantsimp(), # attempt to solve for func, and apply any other hint specific # simplifications sols = solvefunc(eq, func, order, match) if isinstance(sols, Expr): rv = odesimp(sols, func, order, cons(sols), hint) else: rv = [odesimp(s, func, order, cons(s), hint) for s in sols] else: # We still want to integrate (you can disable it separately with the hint) match['simplify'] = False # Some hints can take advantage of this option rv = _handle_Integral(solvefunc(eq, func, order, match), func, order, hint) if ics and not 'power_series' in hint: if isinstance(rv, Expr): solved_constants = solve_ics([rv], [r['func']], cons(rv), ics) rv = rv.subs(solved_constants) else: rv1 = [] for s in rv: solved_constants = solve_ics([s], [r['func']], cons(s), ics) rv1.append(s.subs(solved_constants)) rv = rv1 return rv def solve_ics(sols, funcs, constants, ics): """ Solve for the constants given initial conditions ``sols`` is a list of solutions. ``funcs`` is a list of functions. ``constants`` is a list of constants. ``ics`` is the set of initial/boundary conditions for the differential equation. It should be given in the form of ``{f(x0): x1, f(x).diff(x).subs(x, x2): x3}`` and so on. Returns a dictionary mapping constants to values. ``solution.subs(constants)`` will replace the constants in ``solution``. Example ======= >>> # From dsolve(f(x).diff(x) - f(x), f(x)) >>> from sympy import symbols, Eq, exp, Function >>> from sympy.solvers.ode import solve_ics >>> f = Function('f') >>> x, C1 = symbols('x C1') >>> sols = [Eq(f(x), C1exp(x))] >>> funcs = [f(x)] >>> constants = [C1] >>> ics = {f(0): 2} >>> solved_constants = solve_ics(sols, funcs, constants, ics) >>> solved_constants {C1: 2} >>> sols[0].subs(solved_constants) Eq(f(x), 2exp(x)) """ # Assume ics are of the form f(x0): value or Subs(diff(f(x), x, n), (x, # x0)): value (currently checked by classify_ode). To solve, replace x # with x0, f(x0) with value, then solve for constants. For f^(n)(x0), # differentiate the solution n times, so that f^(n)(x) appears. x = funcs[0].args[0] diff_sols = [] subs_sols = [] diff_variables = set() for funcarg, value in ics.items(): if isinstance(funcarg, AppliedUndef): x0 = funcarg.args[0] matching_func = [f for f in funcs if f.func == funcarg.func][0] S = sols elif isinstance(funcarg, (Subs, Derivative)): if isinstance(funcarg, Subs): # Make sure it stays a subs. Otherwise subs below will produce # a different looking term. funcarg = funcarg.doit() if isinstance(funcarg, Subs): deriv = funcarg.expr x0 = funcarg.point[0] variables = funcarg.expr.variables matching_func = deriv elif isinstance(funcarg, Derivative): deriv = funcarg x0 = funcarg.variables[0] variables = (x,)len(funcarg.variables) matching_func = deriv.subs(x0, x) if variables not in diff_variables: for sol in sols: if sol.has(deriv.expr.func): diff_sols.append(Eq(sol.lhs.diff(variables), sol.rhs.diff(variables))) diff_variables.add(variables) S = diff_sols else: raise NotImplementedError("Unrecognized initial condition") for sol in S: if sol.has(matching_func): sol2 = sol sol2 = sol2.subs(x, x0) sol2 = sol2.subs(funcarg, value) subs_sols.append(sol2) # TODO: Use solveset here try: solved_constants = solve(subs_sols, constants, dict=True) except NotImplementedError: solved_constants = [] # XXX: We can't differentiate between the solution not existing because of # invalid initial conditions, and not existing because solve is not smart # enough. If we could use solveset, this might be improvable, but for now, # we use NotImplementedError in this case. if not solved_constants: raise NotImplementedError("Couldn't solve for initial conditions") if solved_constants == True: raise ValueError("Initial conditions did not produce any solutions for constants. Perhaps they are degenerate.") if len(solved_constants) > 1: raise NotImplementedError("Initial conditions produced too many solutions for constants") if len(solved_constants[0]) != len(constants): raise ValueError("Initial conditions did not produce a solution for all constants. Perhaps they are under-specified.") return solved_constants[0] def classify_ode(eq, func=None, dict=False, ics=None, *kwargs): r""" Returns a tuple of possible :py:meth:`~sympy.solvers.ode.dsolve` classifications for an ODE. The tuple is ordered so that first item is the classification that :py:meth:`~sympy.solvers.ode.dsolve` uses to solve the ODE by default. In general, classifications at the near the beginning of the list will produce better solutions faster than those near the end, thought there are always exceptions. To make :py:meth:`~sympy.solvers.ode.dsolve` use a different classification, use ``dsolve(ODE, func, hint=<classification>)``. See also the :py:meth:`~sympy.solvers.ode.dsolve` docstring for different meta-hints you can use. If ``dict`` is true, :py:meth:`~sympy.solvers.ode.classify_ode` will return a dictionary of ``hint:match`` expression terms. This is intended for internal use by :py:meth:`~sympy.solvers.ode.dsolve`. Note that because dictionaries are ordered arbitrarily, this will most likely not be in the same order as the tuple. You can get help on different hints by executing ``help(ode.ode_hintname)``, where ``hintname`` is the name of the hint without ``_Integral``. See :py:data:`~sympy.solvers.ode.allhints` or the :py:mod:`~sympy.solvers.ode` docstring for a list of all supported hints that can be returned from :py:meth:`~sympy.solvers.ode.classify_ode`. Notes ===== These are remarks on hint names. ``_Integral`` If a classification has ``_Integral`` at the end, it will return the expression with an unevaluated :py:class:`~sympy.integrals.Integral` class in it. Note that a hint may do this anyway if :py:meth:`~sympy.core.expr.Expr.integrate` cannot do the integral, though just using an ``_Integral`` will do so much faster. Indeed, an ``_Integral`` hint will always be faster than its corresponding hint without ``_Integral`` because :py:meth:`~sympy.core.expr.Expr.integrate` is an expensive routine. If :py:meth:`~sympy.solvers.ode.dsolve` hangs, it is probably because :py:meth:`~sympy.core.expr.Expr.integrate` is hanging on a tough or impossible integral. Try using an ``_Integral`` hint or ``all_Integral`` to get it return something. Note that some hints do not have ``_Integral`` counterparts. This is because :py:meth:`~sympy.solvers.ode.integrate` is not used in solving the ODE for those method. For example, `n`\th order linear homogeneous ODEs with constant coefficients do not require integration to solve, so there is no ``nth_linear_homogeneous_constant_coeff_Integrate`` hint. You can easily evaluate any unevaluated :py:class:`~sympy.integrals.Integral`\s in an expression by doing ``expr.doit()``. Ordinals Some hints contain an ordinal such as ``1st_linear``. This is to help differentiate them from other hints, as well as from other methods that may not be implemented yet. If a hint has ``nth`` in it, such as the ``nth_linear`` hints, this means that the method used to applies to ODEs of any order. ``indep`` and ``dep`` Some hints contain the words ``indep`` or ``dep``. These reference the independent variable and the dependent function, respectively. For example, if an ODE is in terms of `f(x)`, then ``indep`` will refer to `x` and ``dep`` will refer to `f`. ``subs`` If a hints has the word ``subs`` in it, it means the the ODE is solved by substituting the expression given after the word ``subs`` for a single dummy variable. This is usually in terms of ``indep`` and ``dep`` as above. The substituted expression will be written only in characters allowed for names of Python objects, meaning operators will be spelled out. For example, ``indep``/``dep`` will be written as ``indep_div_dep``. ``coeff`` The word ``coeff`` in a hint refers to the coefficients of something in the ODE, usually of the derivative terms. See the docstring for the individual methods for more info (``help(ode)``). This is contrast to ``coefficients``, as in ``undetermined_coefficients``, which refers to the common name of a method. ``_best`` Methods that have more than one fundamental way to solve will have a hint for each sub-method and a ``_best`` meta-classification. This will evaluate all hints and return the best, using the same considerations as the normal ``best`` meta-hint. Examples ======== >>> from sympy import Function, classify_ode, Eq >>> from sympy.abc import x >>> f = Function('f') >>> classify_ode(Eq(f(x).diff(x), 0), f(x)) ('nth_algebraic', 'separable', '1st_linear', '1st_homogeneous_coeff_best', '1st_homogeneous_coeff_subs_indep_div_dep', '1st_homogeneous_coeff_subs_dep_div_indep', '1st_power_series', 'lie_group', 'nth_linear_constant_coeff_homogeneous', 'nth_linear_euler_eq_homogeneous', 'nth_algebraic_Integral', 'separable_Integral', '1st_linear_Integral', '1st_homogeneous_coeff_subs_indep_div_dep_Integral', '1st_homogeneous_coeff_subs_dep_div_indep_Integral') >>> classify_ode(f(x).diff(x, 2) + 3f(x).diff(x) + 2f(x) - 4) ('nth_linear_constant_coeff_undetermined_coefficients', 'nth_linear_constant_coeff_variation_of_parameters', 'nth_linear_constant_coeff_variation_of_parameters_Integral') """ ics = sympify(ics) prep = kwargs.pop('prep', True) if func and len(func.args) != 1: raise ValueError("dsolve() and classify_ode() only " "work with functions of one variable, not %s" % func) if prep or func is None: eq, func_ = _preprocess(eq, func) if func is None: func = func_ x = func.args[0] f = func.func y = Dummy('y') xi = kwargs.get('xi') eta = kwargs.get('eta') terms = kwargs.get('n') if isinstance(eq, Equality): if eq.rhs != 0: return classify_ode(eq.lhs - eq.rhs, func, dict=dict, ics=ics, xi=xi, n=terms, eta=eta, prep=False) eq = eq.lhs order = ode_order(eq, f(x)) # hint:matchdict or hint:(tuple of matchdicts) # Also will contain "default":<default hint> and "order":order items. matching_hints = {"order": order} if not order: if dict: matching_hints["default"] = None return matching_hints else: return () df = f(x).diff(x) a = Wild('a', exclude=[f(x)]) b = Wild('b', exclude=[f(x)]) c = Wild('c', exclude=[f(x)]) d = Wild('d', exclude=[df, f(x).diff(x, 2)]) e = Wild('e', exclude=[df]) k = Wild('k', exclude=[df]) n = Wild('n', exclude=[x, f(x), df]) c1 = Wild('c1', exclude=[x]) a2 = Wild('a2', exclude=[x, f(x), df]) b2 = Wild('b2', exclude=[x, f(x), df]) c2 = Wild('c2', exclude=[x, f(x), df]) d2 = Wild('d2', exclude=[x, f(x), df]) a3 = Wild('a3', exclude=[f(x), df, f(x).diff(x, 2)]) b3 = Wild('b3', exclude=[f(x), df, f(x).diff(x, 2)]) c3 = Wild('c3', exclude=[f(x), df, f(x).diff(x, 2)]) r3 = {'xi': xi, 'eta': eta} # Used for the lie_group hint boundary = {} # Used to extract initial conditions C1 = Symbol("C1") eq = expand(eq) # Preprocessing to get the initial conditions out if ics is not None: for funcarg in ics: # Separating derivatives if isinstance(funcarg, (Subs, Derivative)): # f(x).diff(x).subs(x, 0) is a Subs, but f(x).diff(x).subs(x, # y) is a Derivative if isinstance(funcarg, Subs): deriv = funcarg.expr old = funcarg.variables[0] new = funcarg.point[0] elif isinstance(funcarg, Derivative): deriv = funcarg # No information on this. Just assume it was x old = x new = funcarg.variables[0] if (isinstance(deriv, Derivative) and isinstance(deriv.args[0], AppliedUndef) and deriv.args[0].func == f and len(deriv.args[0].args) == 1 and old == x and not new.has(x) and all(i == deriv.variables[0] for i in deriv.variables) and not ics[funcarg].has(f)): dorder = ode_order(deriv, x) temp = 'f' + str(dorder) boundary.update({temp: new, temp + 'val': ics[funcarg]}) else: raise ValueError("Enter valid boundary conditions for Derivatives") # Separating functions elif isinstance(funcarg, AppliedUndef): if (funcarg.func == f and len(funcarg.args) == 1 and not funcarg.args[0].has(x) and not ics[funcarg].has(f)): boundary.update({'f0': funcarg.args[0], 'f0val': ics[funcarg]}) else: raise ValueError("Enter valid boundary conditions for Function") else: raise ValueError("Enter boundary conditions of the form ics={f(point}: value, f(x).diff(x, order).subs(x, point): value}") # Precondition to try remove f(x) from highest order derivative reduced_eq = None if eq.is_Add: deriv_coef = eq.coeff(f(x).diff(x, order)) if deriv_coef not in (1, 0): r = deriv_coef.match(af(x)c1) if r and r[c1]: den = f(x)r[c1] reduced_eq = Add([arg/den for arg in eq.args]) if not reduced_eq: reduced_eq = eq if order == 1: ## Linear case: a(x)y'+b(x)y+c(x) == 0 if eq.is_Add: ind, dep = reduced_eq.as_independent(f) else: u = Dummy('u') ind, dep = (reduced_eq + u).as_independent(f) ind, dep = [tmp.subs(u, 0) for tmp in [ind, dep]] r = {a: dep.coeff(df), b: dep.coeff(f(x)), c: ind} # double check f[a] since the preconditioning may have failed if not r[a].has(f) and not r[b].has(f) and ( r[a]df + r[b]f(x) + r[c]).expand() - reduced_eq == 0: r['a'] = a r['b'] = b r['c'] = c matching_hints["1st_linear"] = r matching_hints["1st_linear_Integral"] = r ## Bernoulli case: a(x)y'+b(x)y+c(x)y*n == 0 r = collect( reduced_eq, f(x), exact=True).match(adf + bf(x) + cf(x)*n) if r and r[c] != 0 and r[n] != 1: # See issue 4676 r['a'] = a r['b'] = b r['c'] = c r['n'] = n matching_hints["Bernoulli"] = r matching_hints["Bernoulli_Integral"] = r ## Riccati special n == -2 case: a2y'+b2y2+c2y/x+d2/x*2 == 0 r = collect(reduced_eq, f(x), exact=True).match(a2df + b2f(x)2 + c2f(x)/x + d2/x*2) if r and r[b2] != 0 and (r[c2] != 0 or r[d2] != 0): r['a2'] = a2 r['b2'] = b2 r['c2'] = c2 r['d2'] = d2 matching_hints["Riccati_special_minus2"] = r # NON-REDUCED FORM OF EQUATION matches r = collect(eq, df, exact=True).match(d + e df) if r: r['d'] = d r['e'] = e r['y'] = y r[d] = r[d].subs(f(x), y) r[e] = r[e].subs(f(x), y) # FIRST ORDER POWER SERIES WHICH NEEDS INITIAL CONDITIONS # TODO: Hint first order series should match only if d/e is analytic. # For now, only d/e and (d/e).diff(arg) is checked for existence at # at a given point. # This is currently done internally in ode_1st_power_series. point = boundary.get('f0', 0) value = boundary.get('f0val', C1) check = cancel(r[d]/r[e]) check1 = check.subs({x: point, y: value}) if not check1.has(oo) and not check1.has(zoo) and \ not check1.has(NaN) and not check1.has(-oo): check2 = (check1.diff(x)).subs({x: point, y: value}) if not check2.has(oo) and not check2.has(zoo) and \ not check2.has(NaN) and not check2.has(-oo): rseries = r.copy() rseries.update({'terms': terms, 'f0': point, 'f0val': value}) matching_hints["1st_power_series"] = rseries r3.update(r) ## Exact Differential Equation: P(x, y) + Q(x, y)y' = 0 where # dP/dy == dQ/dx try: if r[d] != 0: numerator = simplify(r[d].diff(y) - r[e].diff(x)) # The following few conditions try to convert a non-exact # differential equation into an exact one. # References : Differential equations with applications # and historical notes - George E. Simmons if numerator: # If (dP/dy - dQ/dx) / Q = f(x) # then exp(integral(f(x))equation becomes exact factor = simplify(numerator/r[e]) variables = factor.free_symbols if len(variables) == 1 and x == variables.pop(): factor = exp(Integral(factor).doit()) r[d] = factor r[e] = factor matching_hints["1st_exact"] = r matching_hints["1st_exact_Integral"] = r else: # If (dP/dy - dQ/dx) / -P = f(y) # then exp(integral(f(y))equation becomes exact factor = simplify(-numerator/r[d]) variables = factor.free_symbols if len(variables) == 1 and y == variables.pop(): factor = exp(Integral(factor).doit()) r[d] = factor r[e] = factor matching_hints["1st_exact"] = r matching_hints["1st_exact_Integral"] = r else: matching_hints["1st_exact"] = r matching_hints["1st_exact_Integral"] = r except NotImplementedError: # Differentiating the coefficients might fail because of things # like f(2x).diff(x). See issue 4624 and issue 4719. pass # Any first order ODE can be ideally solved by the Lie Group # method matching_hints["lie_group"] = r3 # This match is used for several cases below; we now collect on # f(x) so the matching works. r = collect(reduced_eq, df, exact=True).match(d + edf) if r: # Using r[d] and r[e] without any modification for hints # linear-coefficients and separable-reduced. num, den = r[d], r[e] # ODE = d/e + df r['d'] = d r['e'] = e r['y'] = y r[d] = num.subs(f(x), y) r[e] = den.subs(f(x), y) ## Separable Case: y' == P(y)Q(x) r[d] = separatevars(r[d]) r[e] = separatevars(r[e]) # m1[coeff]m1[x]m1[y] + m2[coeff]m2[x]m2[y]y' m1 = separatevars(r[d], dict=True, symbols=(x, y)) m2 = separatevars(r[e], dict=True, symbols=(x, y)) if m1 and m2: r1 = {'m1': m1, 'm2': m2, 'y': y} matching_hints["separable"] = r1 matching_hints["separable_Integral"] = r1 ## First order equation with homogeneous coefficients: # dy/dx == F(y/x) or dy/dx == F(x/y) ordera = homogeneous_order(r[d], x, y) if ordera is not None: orderb = homogeneous_order(r[e], x, y) if ordera == orderb: # u1=y/x and u2=x/y u1 = Dummy('u1') u2 = Dummy('u2') s = "1st_homogeneous_coeff_subs" s1 = s + "_dep_div_indep" s2 = s + "_indep_div_dep" if simplify((r[d] + u1r[e]).subs({x: 1, y: u1})) != 0: matching_hints[s1] = r matching_hints[s1 + "_Integral"] = r if simplify((r[e] + u2r[d]).subs({x: u2, y: 1})) != 0: matching_hints[s2] = r matching_hints[s2 + "_Integral"] = r if s1 in matching_hints and s2 in matching_hints: matching_hints["1st_homogeneous_coeff_best"] = r ## Linear coefficients of the form # y'+ F((ax + by + c)/(a'x + b'y + c')) = 0 # that can be reduced to homogeneous form. F = num/den params = _linear_coeff_match(F, func) if params: xarg, yarg = params u = Dummy('u') t = Dummy('t') # Dummy substitution for df and f(x). dummy_eq = reduced_eq.subs(((df, t), (f(x), u))) reps = ((x, x + xarg), (u, u + yarg), (t, df), (u, f(x))) dummy_eq = simplify(dummy_eq.subs(reps)) # get the re-cast values for e and d r2 = collect(expand(dummy_eq), [df, f(x)]).match(edf + d) if r2: orderd = homogeneous_order(r2[d], x, f(x)) if orderd is not None: ordere = homogeneous_order(r2[e], x, f(x)) if orderd == ordere: # Match arguments are passed in such a way that it # is coherent with the already existing homogeneous # functions. r2[d] = r2[d].subs(f(x), y) r2[e] = r2[e].subs(f(x), y) r2.update({'xarg': xarg, 'yarg': yarg, 'd': d, 'e': e, 'y': y}) matching_hints["linear_coefficients"] = r2 matching_hints["linear_coefficients_Integral"] = r2 ## Equation of the form y' + (y/x)H(x^ny) = 0 # that can be reduced to separable form factor = simplify(x/f(x)num/den) # Try representing factor in terms of x^ny # where n is lowest power of x in factor; # first remove terms like sqrt(2)3 from factor.atoms(Mul) u = None for mul in ordered(factor.atoms(Mul)): if mul.has(x): _, u = mul.as_independent(x, f(x)) break if u and u.has(f(x)): h = x*(degree(Poly(u.subs(f(x), y), gen=x)))f(x) p = Wild('p') if (u/h == 1) or ((u/h).simplify().match(x*p)): t = Dummy('t') r2 = {'t': t} xpart, ypart = u.as_independent(f(x)) test = factor.subs(((u, t), (1/u, 1/t))) free = test.free_symbols if len(free) == 1 and free.pop() == t: r2.update({'power': xpart.as_base_exp()[1], 'u': test}) matching_hints["separable_reduced"] = r2 matching_hints["separable_reduced_Integral"] = r2 ## Almost-linear equation of the form f(x)g(y)y' + k(x)l(y) + m(x) = 0 r = collect(eq, [df, f(x)]).match(edf + d) if r: r2 = r.copy() r2[c] = S.Zero if r2[d].is_Add: # Separate the terms having f(x) to r[d] and # remaining to r[c] no_f, r2[d] = r2[d].as_independent(f(x)) r2[c] += no_f factor = simplify(r2[d].diff(f(x))/r[e]) if factor and not factor.has(f(x)): r2[d] = factor_terms(r2[d]) u = r2[d].as_independent(f(x), as_Add=False)[1] r2.update({'a': e, 'b': d, 'c': c, 'u': u}) r2[d] /= u r2[e] /= u.diff(f(x)) matching_hints["almost_linear"] = r2 matching_hints["almost_linear_Integral"] = r2 elif order == 2: # Liouville ODE in the form # f(x).diff(x, 2) + g(f(x))(f(x).diff(x))*2 + h(x)f(x).diff(x) # See Goldstein and Braun, "Advanced Methods for the Solution of # Differential Equations", pg. 98 s = df(x).diff(x, 2) + edf*2 + kdf r = reduced_eq.match(s) if r and r[d] != 0: y = Dummy('y') g = simplify(r[e]/r[d]).subs(f(x), y) h = simplify(r[k]/r[d]).subs(f(x), y) if y in h.free_symbols or x in g.free_symbols: pass else: r = {'g': g, 'h': h, 'y': y} matching_hints["Liouville"] = r matching_hints["Liouville_Integral"] = r # Homogeneous second order differential equation of the form # a3f(x).diff(x, 2) + b3f(x).diff(x) + c3, where # for simplicity, a3, b3 and c3 are assumed to be polynomials. # It has a definite power series solution at point x0 if, b3/a3 and c3/a3 # are analytic at x0. deq = a3(f(x).diff(x, 2)) + b3df + c3f(x) r = collect(reduced_eq, [f(x).diff(x, 2), f(x).diff(x), f(x)]).match(deq) ordinary = False if r and r[a3] != 0: if all([r[key].is_polynomial() for key in r]): p = cancel(r[b3]/r[a3]) # Used below q = cancel(r[c3]/r[a3]) # Used below point = kwargs.get('x0', 0) check = p.subs(x, point) if not check.has(oo) and not check.has(NaN) and \ not check.has(zoo) and not check.has(-oo): check = q.subs(x, point) if not check.has(oo) and not check.has(NaN) and \ not check.has(zoo) and not check.has(-oo): ordinary = True r.update({'a3': a3, 'b3': b3, 'c3': c3, 'x0': point, 'terms': terms}) matching_hints["2nd_power_series_ordinary"] = r # Checking if the differential equation has a regular singular point # at x0. It has a regular singular point at x0, if (b3/a3)(x - x0) # and (c3/a3)((x - x0)2) are analytic at x0. if not ordinary: p = cancel((x - point)p) check = p.subs(x, point) if not check.has(oo) and not check.has(NaN) and \ not check.has(zoo) and not check.has(-oo): q = cancel(((x - point)*2)q) check = q.subs(x, point) if not check.has(oo) and not check.has(NaN) and \ not check.has(zoo) and not check.has(-oo): coeff_dict = {'p': p, 'q': q, 'x0': point, 'terms': terms} matching_hints["2nd_power_series_regular"] = coeff_dict if order > 0: # Any ODE that can be solved with a combination of algebra and # integrals e.g.: # d^3/dx^3(x y) = F(x) r = _nth_algebraic_match(reduced_eq, func) if r['solutions']: matching_hints['nth_algebraic'] = r matching_hints['nth_algebraic_Integral'] = r # nth order linear ODE # a_n(x)y^(n) + ... + a_1(x)y' + a_0(x)y = F(x) = b r = _nth_linear_match(reduced_eq, func, order) # Constant coefficient case (a_i is constant for all i) if r and not any(r[i].has(x) for i in r if i >= 0): # Inhomogeneous case: F(x) is not identically 0 if r[-1]: undetcoeff = _undetermined_coefficients_match(r[-1], x) s = "nth_linear_constant_coeff_variation_of_parameters" matching_hints[s] = r matching_hints[s + "_Integral"] = r if undetcoeff['test']: r['trialset'] = undetcoeff['trialset'] matching_hints[ "nth_linear_constant_coeff_undetermined_coefficients" ] = r # Homogeneous case: F(x) is identically 0 else: matching_hints["nth_linear_constant_coeff_homogeneous"] = r # nth order Euler equation a_nxny^(n) + ... + a_1xy' + a_0y = F(x) #In case of Homogeneous euler equation F(x) = 0 def _test_term(coeff, order): r""" Linear Euler ODEs have the form Kx*orderdiff(y(x),x,order) = F(x), where K is independent of x and y(x), order>= 0. So we need to check that for each term, coeff == Kxorder from some K. We have a few cases, since coeff may have several different types. """ if order < 0: raise ValueError("order should be greater than 0") if coeff == 0: return True if order == 0: if x in coeff.free_symbols: return False return True if coeff.is_Mul: if coeff.has(f(x)): return False return xorder in coeff.args elif coeff.is_Pow: return coeff.as_base_exp() == (x, order) elif order == 1: return x == coeff return False # Find coefficient for higest derivative, multiply coefficients to # bring the equation into Euler form if possible r_rescaled = None if r is not None: coeff = r[order] factor = xorder / coeff r_rescaled = {i: factorr[i] for i in r} if r_rescaled and not any(not _test_term(r_rescaled[i], i) for i in r_rescaled if i != 'trialset' and i >= 0): if not r_rescaled[-1]: matching_hints["nth_linear_euler_eq_homogeneous"] = r_rescaled else: matching_hints["nth_linear_euler_eq_nonhomogeneous_variation_of_parameters"] = r_rescaled matching_hints["nth_linear_euler_eq_nonhomogeneous_variation_of_parameters_Integral"] = r_rescaled e, re = posify(r_rescaled[-1].subs(x, exp(x))) undetcoeff = _undetermined_coefficients_match(e.subs(re), x) if undetcoeff['test']: r_rescaled['trialset'] = undetcoeff['trialset'] matching_hints["nth_linear_euler_eq_nonhomogeneous_undetermined_coefficients"] = r_rescaled # Order keys based on allhints. retlist = [i for i in allhints if i in matching_hints] if dict: # Dictionaries are ordered arbitrarily, so make note of which # hint would come first for dsolve(). Use an ordered dict in Py 3. matching_hints["default"] = retlist[0] if retlist else None matching_hints["ordered_hints"] = tuple(retlist) return matching_hints else: return tuple(retlist) def classify_sysode(eq, funcs=None, *kwargs): r""" Returns a dictionary of parameter names and values that define the system of ordinary differential equations in ``eq``. The parameters are further used in :py:meth:`~sympy.solvers.ode.dsolve` for solving that system. The parameter names and values are: 'is_linear' (boolean), which tells whether the given system is linear. Note that "linear" here refers to the operator: terms such as ``xdiff(x,t)`` are nonlinear, whereas terms like ``sin(t)diff(x,t)`` are still linear operators. 'func' (list) contains the :py:class:`~sympy.core.function.Function`s that appear with a derivative in the ODE, i.e. those that we are trying to solve the ODE for. 'order' (dict) with the maximum derivative for each element of the 'func' parameter. 'func_coeff' (dict) with the coefficient for each triple ``(equation number, function, order)```. The coefficients are those subexpressions that do not appear in 'func', and hence can be considered constant for purposes of ODE solving. 'eq' (list) with the equations from ``eq``, sympified and transformed into expressions (we are solving for these expressions to be zero). 'no_of_equations' (int) is the number of equations (same as ``len(eq)``). 'type_of_equation' (string) is an internal classification of the type of ODE. References ========== -http://eqworld.ipmnet.ru/en/solutions/sysode/sode-toc1.htm -A. D. Polyanin and A. V. Manzhirov, Handbook of Mathematics for Engineers and Scientists Examples ======== >>> from sympy import Function, Eq, symbols, diff >>> from sympy.solvers.ode import classify_sysode >>> from sympy.abc import t >>> f, x, y = symbols('f, x, y', cls=Function) >>> k, l, m, n = symbols('k, l, m, n', Integer=True) >>> x1 = diff(x(t), t) ; y1 = diff(y(t), t) >>> x2 = diff(x(t), t, t) ; y2 = diff(y(t), t, t) >>> eq = (Eq(5x1, 12x(t) - 6y(t)), Eq(2y1, 11x(t) + 3y(t))) >>> classify_sysode(eq) {'eq': [-12x(t) + 6y(t) + 5Derivative(x(t), t), -11x(t) - 3y(t) + 2Derivative(y(t), t)], 'func': [x(t), y(t)], 'func_coeff': {(0, x(t), 0): -12, (0, x(t), 1): 5, (0, y(t), 0): 6, (0, y(t), 1): 0, (1, x(t), 0): -11, (1, x(t), 1): 0, (1, y(t), 0): -3, (1, y(t), 1): 2}, 'is_linear': True, 'no_of_equation': 2, 'order': {x(t): 1, y(t): 1}, 'type_of_equation': 'type1'} >>> eq = (Eq(diff(x(t),t), 5tx(t) + t2y(t)), Eq(diff(y(t),t), -t*2x(t) + 5ty(t))) >>> classify_sysode(eq) {'eq': [-t*2y(t) - 5tx(t) + Derivative(x(t), t), t*2x(t) - 5ty(t) + Derivative(y(t), t)], 'func': [x(t), y(t)], 'func_coeff': {(0, x(t), 0): -5t, (0, x(t), 1): 1, (0, y(t), 0): -t2, (0, y(t), 1): 0, (1, x(t), 0): t2, (1, x(t), 1): 0, (1, y(t), 0): -5t, (1, y(t), 1): 1}, 'is_linear': True, 'no_of_equation': 2, 'order': {x(t): 1, y(t): 1}, 'type_of_equation': 'type4'} """ # Sympify equations and convert iterables of equations into # a list of equations def _sympify(eq): return list(map(sympify, eq if iterable(eq) else [eq])) eq, funcs = (_sympify(w) for w in [eq, funcs]) for i, fi in enumerate(eq): if isinstance(fi, Equality): eq[i] = fi.lhs - fi.rhs matching_hints = {"no_of_equation":i+1} matching_hints['eq'] = eq if i==0: raise ValueError("classify_sysode() works for systems of ODEs. " "For scalar ODEs, classify_ode should be used") t = list(list(eq[0].atoms(Derivative))[0].atoms(Symbol))[0] # find all the functions if not given order = dict() if funcs==[None]: funcs = [] for eqs in eq: derivs = eqs.atoms(Derivative) func = set().union([d.atoms(AppliedUndef) for d in derivs]) for func_ in func: funcs.append(func_) funcs = list(set(funcs)) if len(funcs) < len(eq): raise ValueError("Number of functions given is less than number of equations %s" % funcs) func_dict = dict() for func in funcs: if not order.get(func, False): max_order = 0 for i, eqs_ in enumerate(eq): order_ = ode_order(eqs_,func) if max_order < order_: max_order = order_ eq_no = i if eq_no in func_dict: list_func = [] list_func.append(func_dict[eq_no]) list_func.append(func) func_dict[eq_no] = list_func else: func_dict[eq_no] = func order[func] = max_order funcs = [func_dict[i] for i in range(len(func_dict))] matching_hints['func'] = funcs for func in funcs: if isinstance(func, list): for func_elem in func: if len(func_elem.args) != 1: raise ValueError("dsolve() and classify_sysode() work with " "functions of one variable only, not %s" % func) else: if func and len(func.args) != 1: raise ValueError("dsolve() and classify_sysode() work with " "functions of one variable only, not %s" % func) # find the order of all equation in system of odes matching_hints["order"] = order # find coefficients of terms f(t), diff(f(t),t) and higher derivatives # and similarly for other functions g(t), diff(g(t),t) in all equations. # Here j denotes the equation number, funcs[l] denotes the function about # which we are talking about and k denotes the order of function funcs[l] # whose coefficient we are calculating. def linearity_check(eqs, j, func, is_linear_): for k in range(order[func] + 1): func_coef[j, func, k] = collect(eqs.expand(), [diff(func, t, k)]).coeff(diff(func, t, k)) if is_linear_ == True: if func_coef[j, func, k] == 0: if k == 0: coef = eqs.as_independent(func, as_Add=True)[1] for xr in range(1, ode_order(eqs,func) + 1): coef -= eqs.as_independent(diff(func, t, xr), as_Add=True)[1] if coef != 0: is_linear_ = False else: if eqs.as_independent(diff(func, t, k), as_Add=True)[1]: is_linear_ = False else: for func_ in funcs: if isinstance(func_, list): for elem_func_ in func_: dep = func_coef[j, func, k].as_independent(elem_func_, as_Add=True)[1] if dep != 0: is_linear_ = False else: dep = func_coef[j, func, k].as_independent(func_, as_Add=True)[1] if dep != 0: is_linear_ = False return is_linear_ func_coef = {} is_linear = True for j, eqs in enumerate(eq): for func in funcs: if isinstance(func, list): for func_elem in func: is_linear = linearity_check(eqs, j, func_elem, is_linear) else: is_linear = linearity_check(eqs, j, func, is_linear) matching_hints['func_coeff'] = func_coef matching_hints['is_linear'] = is_linear if len(set(order.values()))==1: order_eq = list(matching_hints['order'].values())[0] if matching_hints['is_linear'] == True: if matching_hints['no_of_equation'] == 2: if order_eq == 1: type_of_equation = check_linear_2eq_order1(eq, funcs, func_coef) elif order_eq == 2: type_of_equation = check_linear_2eq_order2(eq, funcs, func_coef) else: type_of_equation = None elif matching_hints['no_of_equation'] == 3: if order_eq == 1: type_of_equation = check_linear_3eq_order1(eq, funcs, func_coef) if type_of_equation==None: type_of_equation = check_linear_neq_order1(eq, funcs, func_coef) else: type_of_equation = None else: if order_eq == 1: type_of_equation = check_linear_neq_order1(eq, funcs, func_coef) else: type_of_equation = None else: if matching_hints['no_of_equation'] == 2: if order_eq == 1: type_of_equation = check_nonlinear_2eq_order1(eq, funcs, func_coef) else: type_of_equation = None elif matching_hints['no_of_equation'] == 3: if order_eq == 1: type_of_equation = check_nonlinear_3eq_order1(eq, funcs, func_coef) else: type_of_equation = None else: type_of_equation = None else: type_of_equation = None matching_hints['type_of_equation'] = type_of_equation return matching_hints def check_linear_2eq_order1(eq, func, func_coef): x = func[0].func y = func[1].func fc = func_coef t = list(list(eq[0].atoms(Derivative))[0].atoms(Symbol))[0] r = dict() # for equations Eq(a1diff(x(t),t), b1x(t) + c1y(t) + d1) # and Eq(a2diff(y(t),t), b2x(t) + c2y(t) + d2) r['a1'] = fc[0,x(t),1] ; r['a2'] = fc[1,y(t),1] r['b1'] = -fc[0,x(t),0]/fc[0,x(t),1] ; r['b2'] = -fc[1,x(t),0]/fc[1,y(t),1] r['c1'] = -fc[0,y(t),0]/fc[0,x(t),1] ; r['c2'] = -fc[1,y(t),0]/fc[1,y(t),1] forcing = [S(0),S(0)] for i in range(2): for j in Add.make_args(eq[i]): if not j.has(x(t), y(t)): forcing[i] += j if not (forcing[0].has(t) or forcing[1].has(t)): # We can handle homogeneous case and simple constant forcings r['d1'] = forcing[0] r['d2'] = forcing[1] else: # Issue #9244: nonhomogeneous linear systems are not supported return None # Conditions to check for type 6 whose equations are Eq(diff(x(t),t), f(t)x(t) + g(t)y(t)) and # Eq(diff(y(t),t), a[f(t) + ah(t)]x(t) + a[g(t) - h(t)]y(t)) p = 0 q = 0 p1 = cancel(r['b2']/(cancel(r['b2']/r['c2']).as_numer_denom()[0])) p2 = cancel(r['b1']/(cancel(r['b1']/r['c1']).as_numer_denom()[0])) for n, i in enumerate([p1, p2]): for j in Mul.make_args(collect_const(i)): if not j.has(t): q = j if q and n==0: if ((r['b2']/j - r['b1'])/(r['c1'] - r['c2']/j)) == j: p = 1 elif q and n==1: if ((r['b1']/j - r['b2'])/(r['c2'] - r['c1']/j)) == j: p = 2 # End of condition for type 6 if r['d1']!=0 or r['d2']!=0: if not r['d1'].has(t) and not r['d2'].has(t): if all(not r[k].has(t) for k in 'a1 a2 b1 b2 c1 c2'.split()): # Equations for type 2 are Eq(a1diff(x(t),t),b1x(t)+c1y(t)+d1) and Eq(a2diff(y(t),t),b2x(t)+c2y(t)+d2) return "type2" else: return None else: if all(not r[k].has(t) for k in 'a1 a2 b1 b2 c1 c2'.split()): # Equations for type 1 are Eq(a1diff(x(t),t),b1x(t)+c1y(t)) and Eq(a2diff(y(t),t),b2x(t)+c2y(t)) return "type1" else: r['b1'] = r['b1']/r['a1'] ; r['b2'] = r['b2']/r['a2'] r['c1'] = r['c1']/r['a1'] ; r['c2'] = r['c2']/r['a2'] if (r['b1'] == r['c2']) and (r['c1'] == r['b2']): # Equation for type 3 are Eq(diff(x(t),t), f(t)x(t) + g(t)y(t)) and Eq(diff(y(t),t), g(t)x(t) + f(t)y(t)) return "type3" elif (r['b1'] == r['c2']) and (r['c1'] == -r['b2']) or (r['b1'] == -r['c2']) and (r['c1'] == r['b2']): # Equation for type 4 are Eq(diff(x(t),t), f(t)x(t) + g(t)y(t)) and Eq(diff(y(t),t), -g(t)x(t) + f(t)y(t)) return "type4" elif (not cancel(r['b2']/r['c1']).has(t) and not cancel((r['c2']-r['b1'])/r['c1']).has(t)) \ or (not cancel(r['b1']/r['c2']).has(t) and not cancel((r['c1']-r['b2'])/r['c2']).has(t)): # Equations for type 5 are Eq(diff(x(t),t), f(t)x(t) + g(t)y(t)) and Eq(diff(y(t),t), ag(t)x(t) + [f(t) + bg(t)]y(t) return "type5" elif p: return "type6" else: # Equations for type 7 are Eq(diff(x(t),t), f(t)x(t) + g(t)y(t)) and Eq(diff(y(t),t), h(t)x(t) + p(t)y(t)) return "type7" def check_linear_2eq_order2(eq, func, func_coef): x = func[0].func y = func[1].func fc = func_coef t = list(list(eq[0].atoms(Derivative))[0].atoms(Symbol))[0] r = dict() a = Wild('a', exclude=[1/t]) b = Wild('b', exclude=[1/t2]) u = Wild('u', exclude=[t, t2]) v = Wild('v', exclude=[t, t2]) w = Wild('w', exclude=[t, t2]) p = Wild('p', exclude=[t, t2]) r['a1'] = fc[0,x(t),2] ; r['a2'] = fc[1,y(t),2] r['b1'] = fc[0,x(t),1] ; r['b2'] = fc[1,x(t),1] r['c1'] = fc[0,y(t),1] ; r['c2'] = fc[1,y(t),1] r['d1'] = fc[0,x(t),0] ; r['d2'] = fc[1,x(t),0] r['e1'] = fc[0,y(t),0] ; r['e2'] = fc[1,y(t),0] const = [S(0), S(0)] for i in range(2): for j in Add.make_args(eq[i]): if not (j.has(x(t)) or j.has(y(t))): const[i] += j r['f1'] = const[0] r['f2'] = const[1] if r['f1']!=0 or r['f2']!=0: if all(not r[k].has(t) for k in 'a1 a2 d1 d2 e1 e2 f1 f2'.split()) \ and r['b1']==r['c1']==r['b2']==r['c2']==0: return "type2" elif all(not r[k].has(t) for k in 'a1 a2 b1 b2 c1 c2 d1 d2 e1 e1'.split()): p = [S(0), S(0)] ; q = [S(0), S(0)] for n, e in enumerate([r['f1'], r['f2']]): if e.has(t): tpart = e.as_independent(t, Mul)[1] for i in Mul.make_args(tpart): if i.has(exp): b, e = i.as_base_exp() co = e.coeff(t) if co and not co.has(t) and co.has(I): p[n] = 1 else: q[n] = 1 else: q[n] = 1 else: q[n] = 1 if p[0]==1 and p[1]==1 and q[0]==0 and q[1]==0: return "type4" else: return None else: return None else: if r['b1']==r['b2']==r['c1']==r['c2']==0 and all(not r[k].has(t) \ for k in 'a1 a2 d1 d2 e1 e2'.split()): return "type1" elif r['b1']==r['e1']==r['c2']==r['d2']==0 and all(not r[k].has(t) \ for k in 'a1 a2 b2 c1 d1 e2'.split()) and r['c1'] == -r['b2'] and \ r['d1'] == r['e2']: return "type3" elif cancel(-r['b2']/r['d2'])==t and cancel(-r['c1']/r['e1'])==t and not \ (r['d2']/r['a2']).has(t) and not (r['e1']/r['a1']).has(t) and \ r['b1']==r['d1']==r['c2']==r['e2']==0: return "type5" elif ((r['a1']/r['d1']).expand()).match((p(ut2+vt+w)*2).expand()) and not \ (cancel(r['a1']r['d2']/(r['a2']r['d1']))).has(t) and not (r['d1']/r['e1']).has(t) and not \ (r['d2']/r['e2']).has(t) and r['b1'] == r['b2'] == r['c1'] == r['c2'] == 0: return "type10" elif not cancel(r['d1']/r['e1']).has(t) and not cancel(r['d2']/r['e2']).has(t) and not \ cancel(r['d1']r['a2']/(r['d2']r['a1'])).has(t) and r['b1']==r['b2']==r['c1']==r['c2']==0: return "type6" elif not cancel(r['b1']/r['c1']).has(t) and not cancel(r['b2']/r['c2']).has(t) and not \ cancel(r['b1']r['a2']/(r['b2']r['a1'])).has(t) and r['d1']==r['d2']==r['e1']==r['e2']==0: return "type7" elif cancel(-r['b2']/r['d2'])==t and cancel(-r['c1']/r['e1'])==t and not \ cancel(r['e1']r['a2']/(r['d2']r['a1'])).has(t) and r['e1'].has(t) \ and r['b1']==r['d1']==r['c2']==r['e2']==0: return "type8" elif (r['b1']/r['a1']).match(a/t) and (r['b2']/r['a2']).match(a/t) and not \ (r['b1']/r['c1']).has(t) and not (r['b2']/r['c2']).has(t) and \ (r['d1']/r['a1']).match(b/t2) and (r['d2']/r['a2']).match(b/t2) \ and not (r['d1']/r['e1']).has(t) and not (r['d2']/r['e2']).has(t): return "type9" elif -r['b1']/r['d1']==-r['c1']/r['e1']==-r['b2']/r['d2']==-r['c2']/r['e2']==t: return "type11" else: return None def check_linear_3eq_order1(eq, func, func_coef): x = func[0].func y = func[1].func z = func[2].func fc = func_coef t = list(list(eq[0].atoms(Derivative))[0].atoms(Symbol))[0] r = dict() r['a1'] = fc[0,x(t),1]; r['a2'] = fc[1,y(t),1]; r['a3'] = fc[2,z(t),1] r['b1'] = fc[0,x(t),0]; r['b2'] = fc[1,x(t),0]; r['b3'] = fc[2,x(t),0] r['c1'] = fc[0,y(t),0]; r['c2'] = fc[1,y(t),0]; r['c3'] = fc[2,y(t),0] r['d1'] = fc[0,z(t),0]; r['d2'] = fc[1,z(t),0]; r['d3'] = fc[2,z(t),0] forcing = [S(0), S(0), S(0)] for i in range(3): for j in Add.make_args(eq[i]): if not j.has(x(t), y(t), z(t)): forcing[i] += j if forcing[0].has(t) or forcing[1].has(t) or forcing[2].has(t): # We can handle homogeneous case and simple constant forcings. # Issue #9244: nonhomogeneous linear systems are not supported return None if all(not r[k].has(t) for k in 'a1 a2 a3 b1 b2 b3 c1 c2 c3 d1 d2 d3'.split()): if r['c1']==r['d1']==r['d2']==0: return 'type1' elif r['c1'] == -r['b2'] and r['d1'] == -r['b3'] and r['d2'] == -r['c3'] \ and r['b1'] == r['c2'] == r['d3'] == 0: return 'type2' elif r['b1'] == r['c2'] == r['d3'] == 0 and r['c1']/r['a1'] == -r['d1']/r['a1'] \ and r['d2']/r['a2'] == -r['b2']/r['a2'] and r['b3']/r['a3'] == -r['c3']/r['a3']: return 'type3' else: return None else: for k1 in 'c1 d1 b2 d2 b3 c3'.split(): if r[k1] == 0: continue else: if all(not cancel(r[k1]/r[k]).has(t) for k in 'd1 b2 d2 b3 c3'.split() if r[k]!=0) \ and all(not cancel(r[k1]/(r['b1'] - r[k])).has(t) for k in 'b1 c2 d3'.split() if r['b1']!=r[k]): return 'type4' else: break return None def check_linear_neq_order1(eq, func, func_coef): x = func[0].func y = func[1].func z = func[2].func fc = func_coef t = list(list(eq[0].atoms(Derivative))[0].atoms(Symbol))[0] r = dict() n = len(eq) for i in range(n): for j in range(n): if (fc[i,func[j],0]/fc[i,func[i],1]).has(t): return None if len(eq)==3: return 'type6' return 'type1' def check_nonlinear_2eq_order1(eq, func, func_coef): t = list(list(eq[0].atoms(Derivative))[0].atoms(Symbol))[0] f = Wild('f') g = Wild('g') u, v = symbols('u, v', cls=Dummy) def check_type(x, y): r1 = eq[0].match(tdiff(x(t),t) - x(t) + f) r2 = eq[1].match(tdiff(y(t),t) - y(t) + g) if not (r1 and r2): r1 = eq[0].match(diff(x(t),t) - x(t)/t + f/t) r2 = eq[1].match(diff(y(t),t) - y(t)/t + g/t) if not (r1 and r2): r1 = (-eq[0]).match(tdiff(x(t),t) - x(t) + f) r2 = (-eq[1]).match(tdiff(y(t),t) - y(t) + g) if not (r1 and r2): r1 = (-eq[0]).match(diff(x(t),t) - x(t)/t + f/t) r2 = (-eq[1]).match(diff(y(t),t) - y(t)/t + g/t) if r1 and r2 and not (r1[f].subs(diff(x(t),t),u).subs(diff(y(t),t),v).has(t) \ or r2[g].subs(diff(x(t),t),u).subs(diff(y(t),t),v).has(t)): return 'type5' else: return None for func_ in func: if isinstance(func_, list): x = func[0][0].func y = func[0][1].func eq_type = check_type(x, y) if not eq_type: eq_type = check_type(y, x) return eq_type x = func[0].func y = func[1].func fc = func_coef n = Wild('n', exclude=[x(t),y(t)]) f1 = Wild('f1', exclude=[v,t]) f2 = Wild('f2', exclude=[v,t]) g1 = Wild('g1', exclude=[u,t]) g2 = Wild('g2', exclude=[u,t]) for i in range(2): eqs = 0 for terms in Add.make_args(eq[i]): eqs += terms/fc[i,func[i],1] eq[i] = eqs r = eq[0].match(diff(x(t),t) - x(t)nf) if r: g = (diff(y(t),t) - eq[1])/r[f] if r and not (g.has(x(t)) or g.subs(y(t),v).has(t) or r[f].subs(x(t),u).subs(y(t),v).has(t)): return 'type1' r = eq[0].match(diff(x(t),t) - exp(nx(t))f) if r: g = (diff(y(t),t) - eq[1])/r[f] if r and not (g.has(x(t)) or g.subs(y(t),v).has(t) or r[f].subs(x(t),u).subs(y(t),v).has(t)): return 'type2' g = Wild('g') r1 = eq[0].match(diff(x(t),t) - f) r2 = eq[1].match(diff(y(t),t) - g) if r1 and r2 and not (r1[f].subs(x(t),u).subs(y(t),v).has(t) or \ r2[g].subs(x(t),u).subs(y(t),v).has(t)): return 'type3' r1 = eq[0].match(diff(x(t),t) - f) r2 = eq[1].match(diff(y(t),t) - g) num, den = ( (r1[f].subs(x(t),u).subs(y(t),v))/ (r2[g].subs(x(t),u).subs(y(t),v))).as_numer_denom() R1 = num.match(f1g1) R2 = den.match(f2g2) phi = (r1[f].subs(x(t),u).subs(y(t),v))/num if R1 and R2: return 'type4' return None def check_nonlinear_2eq_order2(eq, func, func_coef): return None def check_nonlinear_3eq_order1(eq, func, func_coef): x = func[0].func y = func[1].func z = func[2].func fc = func_coef t = list(list(eq[0].atoms(Derivative))[0].atoms(Symbol))[0] u, v, w = symbols('u, v, w', cls=Dummy) a = Wild('a', exclude=[x(t), y(t), z(t), t]) b = Wild('b', exclude=[x(t), y(t), z(t), t]) c = Wild('c', exclude=[x(t), y(t), z(t), t]) f = Wild('f') F1 = Wild('F1') F2 = Wild('F2') F3 = Wild('F3') for i in range(3): eqs = 0 for terms in Add.make_args(eq[i]): eqs += terms/fc[i,func[i],1] eq[i] = eqs r1 = eq[0].match(diff(x(t),t) - ay(t)z(t)) r2 = eq[1].match(diff(y(t),t) - bz(t)x(t)) r3 = eq[2].match(diff(z(t),t) - cx(t)y(t)) if r1 and r2 and r3: num1, den1 = r1[a].as_numer_denom() num2, den2 = r2[b].as_numer_denom() num3, den3 = r3[c].as_numer_denom() if solve([num1u-den1(v-w), num2v-den2(w-u), num3w-den3(u-v)],[u, v]): return 'type1' r = eq[0].match(diff(x(t),t) - y(t)z(t)f) if r: r1 = collect_const(r[f]).match(af) r2 = ((diff(y(t),t) - eq[1])/r1[f]).match(bz(t)x(t)) r3 = ((diff(z(t),t) - eq[2])/r1[f]).match(cx(t)y(t)) if r1 and r2 and r3: num1, den1 = r1[a].as_numer_denom() num2, den2 = r2[b].as_numer_denom() num3, den3 = r3[c].as_numer_denom() if solve([num1u-den1(v-w), num2v-den2(w-u), num3w-den3(u-v)],[u, v]): return 'type2' r = eq[0].match(diff(x(t),t) - (F2-F3)) if r: r1 = collect_const(r[F2]).match(cF2) r1.update(collect_const(r[F3]).match(bF3)) if r1: if eq[1].has(r1[F2]) and not eq[1].has(r1[F3]): r1[F2], r1[F3] = r1[F3], r1[F2] r1[c], r1[b] = -r1[b], -r1[c] r2 = eq[1].match(diff(y(t),t) - ar1[F3] + r1[c]F1) if r2: r3 = (eq[2] == diff(z(t),t) - r1[b]r2[F1] + r2[a]r1[F2]) if r1 and r2 and r3: return 'type3' r = eq[0].match(diff(x(t),t) - z(t)F2 + y(t)F3) if r: r1 = collect_const(r[F2]).match(cF2) r1.update(collect_const(r[F3]).match(bF3)) if r1: if eq[1].has(r1[F2]) and not eq[1].has(r1[F3]): r1[F2], r1[F3] = r1[F3], r1[F2] r1[c], r1[b] = -r1[b], -r1[c] r2 = (diff(y(t),t) - eq[1]).match(ax(t)r1[F3] - r1[c]z(t)F1) if r2: r3 = (diff(z(t),t) - eq[2] == r1[b]y(t)r2[F1] - r2[a]x(t)r1[F2]) if r1 and r2 and r3: return 'type4' r = (diff(x(t),t) - eq[0]).match(x(t)(F2 - F3)) if r: r1 = collect_const(r[F2]).match(cF2) r1.update(collect_const(r[F3]).match(bF3)) if r1: if eq[1].has(r1[F2]) and not eq[1].has(r1[F3]): r1[F2], r1[F3] = r1[F3], r1[F2] r1[c], r1[b] = -r1[b], -r1[c] r2 = (diff(y(t),t) - eq[1]).match(y(t)(ar1[F3] - r1[c]F1)) if r2: r3 = (diff(z(t),t) - eq[2] == z(t)(r1[b]r2[F1] - r2[a]r1[F2])) if r1 and r2 and r3: return 'type5' return None def check_nonlinear_3eq_order2(eq, func, func_coef): return None def checksysodesol(eqs, sols, func=None): r""" Substitutes corresponding ``sols`` for each functions into each ``eqs`` and checks that the result of substitutions for each equation is ``0``. The equations and solutions passed can be any iterable. This only works when each ``sols`` have one function only, like `x(t)` or `y(t)`. For each function, ``sols`` can have a single solution or a list of solutions. In most cases it will not be necessary to explicitly identify the function, but if the function cannot be inferred from the original equation it can be supplied through the ``func`` argument. When a sequence of equations is passed, the same sequence is used to return the result for each equation with each function substituted with corresponding solutions. It tries the following method to find zero equivalence for each equation: Substitute the solutions for functions, like `x(t)` and `y(t)` into the original equations containing those functions. This function returns a tuple. The first item in the tuple is ``True`` if the substitution results for each equation is ``0``, and ``False`` otherwise. The second item in the tuple is what the substitution results in. Each element of the ``list`` should always be ``0`` corresponding to each equation if the first item is ``True``. Note that sometimes this function may return ``False``, but with an expression that is identically equal to ``0``, instead of returning ``True``. This is because :py:meth:`~sympy.simplify.simplify.simplify` cannot reduce the expression to ``0``. If an expression returned by each function vanishes identically, then ``sols`` really is a solution to ``eqs``. If this function seems to hang, it is probably because of a difficult simplification. Examples ======== >>> from sympy import Eq, diff, symbols, sin, cos, exp, sqrt, S, Function >>> from sympy.solvers.ode import checksysodesol >>> C1, C2 = symbols('C1:3') >>> t = symbols('t') >>> x, y = symbols('x, y', cls=Function) >>> eq = (Eq(diff(x(t),t), x(t) + y(t) + 17), Eq(diff(y(t),t), -2x(t) + y(t) + 12)) >>> sol = [Eq(x(t), (C1sin(sqrt(2)t) + C2cos(sqrt(2)t))exp(t) - S(5)/3), ... Eq(y(t), (sqrt(2)C1cos(sqrt(2)t) - sqrt(2)C2sin(sqrt(2)t))exp(t) - S(46)/3)] >>> checksysodesol(eq, sol) (True, [0, 0]) >>> eq = (Eq(diff(x(t),t),x(t)y(t)4), Eq(diff(y(t),t),y(t)3)) >>> sol = [Eq(x(t), C1exp(-1/(4(C2 + t)))), Eq(y(t), -sqrt(2)sqrt(-1/(C2 + t))/2), ... Eq(x(t), C1exp(-1/(4(C2 + t)))), Eq(y(t), sqrt(2)sqrt(-1/(C2 + t))/2)] >>> checksysodesol(eq, sol) (True, [0, 0]) """ def _sympify(eq): return list(map(sympify, eq if iterable(eq) else [eq])) eqs = _sympify(eqs) for i in range(len(eqs)): if isinstance(eqs[i], Equality): eqs[i] = eqs[i].lhs - eqs[i].rhs if func is None: funcs = [] for eq in eqs: derivs = eq.atoms(Derivative) func = set().union([d.atoms(AppliedUndef) for d in derivs]) for func_ in func: funcs.append(func_) funcs = list(set(funcs)) if not all(isinstance(func, AppliedUndef) and len(func.args) == 1 for func in funcs)\ and len({func.args for func in funcs})!=1: raise ValueError("func must be a function of one variable, not %s" % func) for sol in sols: if len(sol.atoms(AppliedUndef)) != 1: raise ValueError("solutions should have one function only") if len(funcs) != len({sol.lhs for sol in sols}): raise ValueError("number of solutions provided does not match the number of equations") t = funcs[0].args[0] dictsol = dict() for sol in sols: func = list(sol.atoms(AppliedUndef))[0] if sol.rhs == func: sol = sol.reversed solved = sol.lhs == func and not sol.rhs.has(func) if not solved: rhs = solve(sol, func) if not rhs: raise NotImplementedError else: rhs = sol.rhs dictsol[func] = rhs checkeq = [] for eq in eqs: for func in funcs: eq = sub_func_doit(eq, func, dictsol[func]) ss = simplify(eq) if ss != 0: eq = ss.expand(force=True) else: eq = 0 checkeq.append(eq) if len(set(checkeq)) == 1 and list(set(checkeq))[0] == 0: return (True, checkeq) else: return (False, checkeq) @vectorize(0) def odesimp(eq, func, order, constants, hint): r""" Simplifies ODEs, including trying to solve for ``func`` and running :py:meth:`~sympy.solvers.ode.constantsimp`. It may use knowledge of the type of solution that the hint returns to apply additional simplifications. It also attempts to integrate any :py:class:`~sympy.integrals.Integral`\s in the expression, if the hint is not an ``_Integral`` hint. This function should have no effect on expressions returned by :py:meth:`~sympy.solvers.ode.dsolve`, as :py:meth:`~sympy.solvers.ode.dsolve` already calls :py:meth:`~sympy.solvers.ode.odesimp`, but the individual hint functions do not call :py:meth:`~sympy.solvers.ode.odesimp` (because the :py:meth:`~sympy.solvers.ode.dsolve` wrapper does). Therefore, this function is designed for mainly internal use. Examples ======== >>> from sympy import sin, symbols, dsolve, pprint, Function >>> from sympy.solvers.ode import odesimp >>> x , u2, C1= symbols('x,u2,C1') >>> f = Function('f') >>> eq = dsolve(xf(x).diff(x) - f(x) - xsin(f(x)/x), f(x), ... hint='1st_homogeneous_coeff_subs_indep_div_dep_Integral', ... simplify=False) >>> pprint(eq, wrap_line=False) x ---- f(x) / \| \| / 1 \ \| -\|u2 + -------\| \| \| /1 \\| \| \| sin\|--\|\| \| \ \u2// log(f(x)) = log(C1) + \| ---------------- d(u2) \| 2 \| u2 \| / >>> pprint(odesimp(eq, f(x), 1, {C1}, ... hint='1st_homogeneous_coeff_subs_indep_div_dep' ... )) #doctest: +SKIP x --------- = C1 /f(x)\ tan\|----\| \2x / """ x = func.args[0] f = func.func C1 = get_numbered_constants(eq, num=1) # First, integrate if the hint allows it. eq = _handle_Integral(eq, func, order, hint) if hint.startswith("nth_linear_euler_eq_nonhomogeneous"): eq = simplify(eq) if not isinstance(eq, Equality): raise TypeError("eq should be an instance of Equality") # Second, clean up the arbitrary constants. # Right now, nth linear hints can put as many as 2order constants in an # expression. If that number grows with another hint, the third argument # here should be raised accordingly, or constantsimp() rewritten to handle # an arbitrary number of constants. eq = constantsimp(eq, constants) # Lastly, now that we have cleaned up the expression, try solving for func. # When CRootOf is implemented in solve(), we will want to return a CRootOf # every time instead of an Equality. # Get the f(x) on the left if possible. if eq.rhs == func and not eq.lhs.has(func): eq = [Eq(eq.rhs, eq.lhs)] # make sure we are working with lists of solutions in simplified form. if eq.lhs == func and not eq.rhs.has(func): # The solution is already solved eq = [eq] # special simplification of the rhs if hint.startswith("nth_linear_constant_coeff"): # Collect terms to make the solution look nice. # This is also necessary for constantsimp to remove unnecessary # terms from the particular solution from variation of parameters # # Collect is not behaving reliably here. The results for # some linear constant-coefficient equations with repeated # roots do not properly simplify all constants sometimes. # 'collectterms' gives different orders sometimes, and results # differ in collect based on that order. The # sort-reverse trick fixes things, but may fail in the # future. In addition, collect is splitting exponentials with # rational powers for no reason. We have to do a match # to fix this using Wilds. global collectterms try: collectterms.sort(key=default_sort_key) collectterms.reverse() except Exception: pass assert len(eq) == 1 and eq[0].lhs == f(x) sol = eq[0].rhs sol = expand_mul(sol) for i, reroot, imroot in collectterms: sol = collect(sol, xiexp(rerootx)sin(abs(imroot)x)) sol = collect(sol, xiexp(rerootx)cos(imrootx)) for i, reroot, imroot in collectterms: sol = collect(sol, xiexp(rerootx)) del collectterms # Collect is splitting exponentials with rational powers for # no reason. We call powsimp to fix. sol = powsimp(sol) eq[0] = Eq(f(x), sol) else: # The solution is not solved, so try to solve it try: floats = any(i.is_Float for i in eq.atoms(Number)) eqsol = solve(eq, func, force=True, rational=False if floats else None) if not eqsol: raise NotImplementedError except (NotImplementedError, PolynomialError): eq = [eq] else: def _expand(expr): numer, denom = expr.as_numer_denom() if denom.is_Add: return expr else: return powsimp(expr.expand(), combine='exp', deep=True) # XXX: the rest of odesimp() expects each ``t`` to be in a # specific normal form: rational expression with numerator # expanded, but with combined exponential functions (at # least in this setup all tests pass). eq = [Eq(f(x), _expand(t)) for t in eqsol] # special simplification of the lhs. if hint.startswith("1st_homogeneous_coeff"): for j, eqi in enumerate(eq): newi = logcombine(eqi, force=True) if isinstance(newi.lhs, log) and newi.rhs == 0: newi = Eq(newi.lhs.args[0]/C1, C1) eq[j] = newi # We cleaned up the constants before solving to help the solve engine with # a simpler expression, but the solved expression could have introduced # things like -C1, so rerun constantsimp() one last time before returning. for i, eqi in enumerate(eq): eq[i] = constantsimp(eqi, constants) eq[i] = constant_renumber(eq[i], 'C', 1, 2order) # If there is only 1 solution, return it; # otherwise return the list of solutions. if len(eq) == 1: eq = eq[0] return eq def checkodesol(ode, sol, func=None, order='auto', solve_for_func=True): r""" Substitutes ``sol`` into ``ode`` and checks that the result is ``0``. This only works when ``func`` is one function, like `f(x)`. ``sol`` can be a single solution or a list of solutions. Each solution may be an :py:class:`~sympy.core.relational.Equality` that the solution satisfies, e.g. ``Eq(f(x), C1), Eq(f(x) + C1, 0)``; or simply an :py:class:`~sympy.core.expr.Expr`, e.g. ``f(x) - C1``. In most cases it will not be necessary to explicitly identify the function, but if the function cannot be inferred from the original equation it can be supplied through the ``func`` argument. If a sequence of solutions is passed, the same sort of container will be used to return the result for each solution. It tries the following methods, in order, until it finds zero equivalence: 1. Substitute the solution for `f` in the original equation. This only works if ``ode`` is solved for `f`. It will attempt to solve it first unless ``solve_for_func == False``. 2. Take `n` derivatives of the solution, where `n` is the order of ``ode``, and check to see if that is equal to the solution. This only works on exact ODEs. 3. Take the 1st, 2nd, ..., `n`\th derivatives of the solution, each time solving for the derivative of `f` of that order (this will always be possible because `f` is a linear operator). Then back substitute each derivative into ``ode`` in reverse order. This function returns a tuple. The first item in the tuple is ``True`` if the substitution results in ``0``, and ``False`` otherwise. The second item in the tuple is what the substitution results in. It should always be ``0`` if the first item is ``True``. Sometimes this function will return ``False`` even when an expression is identically equal to ``0``. This happens when :py:meth:`~sympy.simplify.simplify.simplify` does not reduce the expression to ``0``. If an expression returned by this function vanishes identically, then ``sol`` really is a solution to the ``ode``. If this function seems to hang, it is probably because of a hard simplification. To use this function to test, test the first item of the tuple. Examples ======== >>> from sympy import Eq, Function, checkodesol, symbols >>> x, C1 = symbols('x,C1') >>> f = Function('f') >>> checkodesol(f(x).diff(x), Eq(f(x), C1)) (True, 0) >>> assert checkodesol(f(x).diff(x), C1)[0] >>> assert not checkodesol(f(x).diff(x), x)[0] >>> checkodesol(f(x).diff(x, 2), x*2) (False, 2) """ if not isinstance(ode, Equality): ode = Eq(ode, 0) if func is None: try: _, func = _preprocess(ode.lhs) except ValueError: funcs = [s.atoms(AppliedUndef) for s in ( sol if is_sequence(sol, set) else [sol])] funcs = set().union(funcs) if len(funcs) != 1: raise ValueError( 'must pass func arg to checkodesol for this case.') func = funcs.pop() if not isinstance(func, AppliedUndef) or len(func.args) != 1: raise ValueError( "func must be a function of one variable, not %s" % func) if is_sequence(sol, set): return type(sol)([checkodesol(ode, i, order=order, solve_for_func=solve_for_func) for i in sol]) if not isinstance(sol, Equality): sol = Eq(func, sol) elif sol.rhs == func: sol = sol.reversed if order == 'auto': order = ode_order(ode, func) solved = sol.lhs == func and not sol.rhs.has(func) if solve_for_func and not solved: rhs = solve(sol, func) if rhs: eqs = [Eq(func, t) for t in rhs] if len(rhs) == 1: eqs = eqs[0] return checkodesol(ode, eqs, order=order, solve_for_func=False) s = True testnum = 0 x = func.args[0] while s: if testnum == 0: # First pass, try substituting a solved solution directly into the # ODE. This has the highest chance of succeeding. ode_diff = ode.lhs - ode.rhs if sol.lhs == func: s = sub_func_doit(ode_diff, func, sol.rhs) else: testnum += 1 continue ss = simplify(s) if ss: # with the new numer_denom in power.py, if we do a simple # expansion then testnum == 0 verifies all solutions. s = ss.expand(force=True) else: s = 0 testnum += 1 elif testnum == 1: # Second pass. If we cannot substitute f, try seeing if the nth # derivative is equal, this will only work for odes that are exact, # by definition. s = simplify( trigsimp(diff(sol.lhs, x, order) - diff(sol.rhs, x, order)) - trigsimp(ode.lhs) + trigsimp(ode.rhs)) # s2 = simplify( # diff(sol.lhs, x, order) - diff(sol.rhs, x, order) - \ # ode.lhs + ode.rhs) testnum += 1 elif testnum == 2: # Third pass. Try solving for df/dx and substituting that into the # ODE. Thanks to Chris Smith for suggesting this method. Many of # the comments below are his, too. # The method: # - Take each of 1..n derivatives of the solution. # - Solve each nth derivative for d^(n)f/dx^(n) # (the differential of that order) # - Back substitute into the ODE in decreasing order # (i.e., n, n-1, ...) # - Check the result for zero equivalence if sol.lhs == func and not sol.rhs.has(func): diffsols = {0: sol.rhs} elif sol.rhs == func and not sol.lhs.has(func): diffsols = {0: sol.lhs} else: diffsols = {} sol = sol.lhs - sol.rhs for i in range(1, order + 1): # Differentiation is a linear operator, so there should always # be 1 solution. Nonetheless, we test just to make sure. # We only need to solve once. After that, we automatically # have the solution to the differential in the order we want. if i == 1: ds = sol.diff(x) try: sdf = solve(ds, func.diff(x, i)) if not sdf: raise NotImplementedError except NotImplementedError: testnum += 1 break else: diffsols[i] = sdf[0] else: # This is what the solution says df/dx should be. diffsols[i] = diffsols[i - 1].diff(x) # Make sure the above didn't fail. if testnum > 2: continue else: # Substitute it into ODE to check for self consistency. lhs, rhs = ode.lhs, ode.rhs for i in range(order, -1, -1): if i == 0 and 0 not in diffsols: # We can only substitute f(x) if the solution was # solved for f(x). break lhs = sub_func_doit(lhs, func.diff(x, i), diffsols[i]) rhs = sub_func_doit(rhs, func.diff(x, i), diffsols[i]) ode_or_bool = Eq(lhs, rhs) ode_or_bool = simplify(ode_or_bool) if isinstance(ode_or_bool, (bool, BooleanAtom)): if ode_or_bool: lhs = rhs = S.Zero else: lhs = ode_or_bool.lhs rhs = ode_or_bool.rhs # No sense in overworking simplify -- just prove that the # numerator goes to zero num = trigsimp((lhs - rhs).as_numer_denom()[0]) # since solutions are obtained using force=True we test # using the same level of assumptions ## replace function with dummy so assumptions will work _func = Dummy('func') num = num.subs(func, _func) ## posify the expression num, reps = posify(num) s = simplify(num).xreplace(reps).xreplace({_func: func}) testnum += 1 else: break if not s: return (True, s) elif s is True: # The code above never was able to change s raise NotImplementedError("Unable to test if " + str(sol) + " is a solution to " + str(ode) + ".") else: return (False, s) def ode_sol_simplicity(sol, func, trysolving=True): r""" Returns an extended integer representing how simple a solution to an ODE is. The following things are considered, in order from most simple to least: - ``sol`` is solved for ``func``. - ``sol`` is not solved for ``func``, but can be if passed to solve (e.g., a solution returned by ``dsolve(ode, func, simplify=False``). - If ``sol`` is not solved for ``func``, then base the result on the length of ``sol``, as computed by ``len(str(sol))``. - If ``sol`` has any unevaluated :py:class:`~sympy.integrals.Integral`\s, this will automatically be considered less simple than any of the above. This function returns an integer such that if solution A is simpler than solution B by above metric, then ``ode_sol_simplicity(sola, func) < ode_sol_simplicity(solb, func)``. Currently, the following are the numbers returned, but if the heuristic is ever improved, this may change. Only the ordering is guaranteed. +----------------------------------------------+-------------------+ \| Simplicity \| Return \| +==============================================+===================+ \| ``sol`` solved for ``func`` \| ``-2`` \| +----------------------------------------------+-------------------+ \| ``sol`` not solved for ``func`` but can be \| ``-1`` \| +----------------------------------------------+-------------------+ \| ``sol`` is not solved nor solvable for \| ``len(str(sol))`` \| \| ``func`` \| \| +----------------------------------------------+-------------------+ \| ``sol`` contains an \| ``oo`` \| \| :py:class:`~sympy.integrals.Integral` \| \| +----------------------------------------------+-------------------+ ``oo`` here means the SymPy infinity, which should compare greater than any integer. If you already know :py:meth:`~sympy.solvers.solvers.solve` cannot solve ``sol``, you can use ``trysolving=False`` to skip that step, which is the only potentially slow step. For example, :py:meth:`~sympy.solvers.ode.dsolve` with the ``simplify=False`` flag should do this. If ``sol`` is a list of solutions, if the worst solution in the list returns ``oo`` it returns that, otherwise it returns ``len(str(sol))``, that is, the length of the string representation of the whole list. Examples ======== This function is designed to be passed to ``min`` as the key argument, such as ``min(listofsolutions, key=lambda i: ode_sol_simplicity(i, f(x)))``. >>> from sympy import symbols, Function, Eq, tan, cos, sqrt, Integral >>> from sympy.solvers.ode import ode_sol_simplicity >>> x, C1, C2 = symbols('x, C1, C2') >>> f = Function('f') >>> ode_sol_simplicity(Eq(f(x), C1x2), f(x)) -2 >>> ode_sol_simplicity(Eq(x2 + f(x), C1), f(x)) -1 >>> ode_sol_simplicity(Eq(f(x), C1Integral(2x, x)), f(x)) oo >>> eq1 = Eq(f(x)/tan(f(x)/(2x)), C1) >>> eq2 = Eq(f(x)/tan(f(x)/(2x) + f(x)), C2) >>> [ode_sol_simplicity(eq, f(x)) for eq in [eq1, eq2]] [28, 35] >>> min([eq1, eq2], key=lambda i: ode_sol_simplicity(i, f(x))) Eq(f(x)/tan(f(x)/(2x)), C1) """ # TODO: if two solutions are solved for f(x), we still want to be # able to get the simpler of the two # See the docstring for the coercion rules. We check easier (faster) # things here first, to save time. if iterable(sol): # See if there are Integrals for i in sol: if ode_sol_simplicity(i, func, trysolving=trysolving) == oo: return oo return len(str(sol)) if sol.has(Integral): return oo # Next, try to solve for func. This code will change slightly when CRootOf # is implemented in solve(). Probably a CRootOf solution should fall # somewhere between a normal solution and an unsolvable expression. # First, see if they are already solved if sol.lhs == func and not sol.rhs.has(func) or \ sol.rhs == func and not sol.lhs.has(func): return -2 # We are not so lucky, try solving manually if trysolving: try: sols = solve(sol, func) if not sols: raise NotImplementedError except NotImplementedError: pass else: return -1 # Finally, a naive computation based on the length of the string version # of the expression. This may favor combined fractions because they # will not have duplicate denominators, and may slightly favor expressions # with fewer additions and subtractions, as those are separated by spaces # by the printer. # Additional ideas for simplicity heuristics are welcome, like maybe # checking if a equation has a larger domain, or if constantsimp has # introduced arbitrary constants numbered higher than the order of a # given ODE that sol is a solution of. return len(str(sol)) def _get_constant_subexpressions(expr, Cs): Cs = set(Cs) Ces = [] def _recursive_walk(expr): expr_syms = expr.free_symbols if len(expr_syms) > 0 and expr_syms.issubset(Cs): Ces.append(expr) else: if expr.func == exp: expr = expr.expand(mul=True) if expr.func in (Add, Mul): d = sift(expr.args, lambda i : i.free_symbols.issubset(Cs)) if len(d[True]) > 1: x = expr.func(d[True]) if not x.is_number: Ces.append(x) elif isinstance(expr, Integral): if expr.free_symbols.issubset(Cs) and \ all(len(x) == 3 for x in expr.limits): Ces.append(expr) for i in expr.args: _recursive_walk(i) return _recursive_walk(expr) return Ces def __remove_linear_redundancies(expr, Cs): cnts = {i: expr.count(i) for i in Cs} Cs = [i for i in Cs if cnts[i] > 0] def _linear(expr): if isinstance(expr, Add): xs = [i for i in Cs if expr.count(i)==cnts[i] \ and 0 == expr.diff(i, 2)] d = {} for x in xs: y = expr.diff(x) if y not in d: d[y]=[] d[y].append(x) for y in d: if len(d[y]) > 1: d[y].sort(key=str) for x in d[y][1:]: expr = expr.subs(x, 0) return expr def _recursive_walk(expr): if len(expr.args) != 0: expr = expr.func([_recursive_walk(i) for i in expr.args]) expr = _linear(expr) return expr if isinstance(expr, Equality): lhs, rhs = [_recursive_walk(i) for i in expr.args] f = lambda i: isinstance(i, Number) or i in Cs if isinstance(lhs, Symbol) and lhs in Cs: rhs, lhs = lhs, rhs if lhs.func in (Add, Symbol) and rhs.func in (Add, Symbol): dlhs = sift([lhs] if isinstance(lhs, AtomicExpr) else lhs.args, f) drhs = sift([rhs] if isinstance(rhs, AtomicExpr) else rhs.args, f) for i in [True, False]: for hs in [dlhs, drhs]: if i not in hs: hs[i] = [0] # this calculation can be simplified lhs = Add(dlhs[False]) - Add(drhs[False]) rhs = Add(drhs[True]) - Add(dlhs[True]) elif lhs.func in (Mul, Symbol) and rhs.func in (Mul, Symbol): dlhs = sift([lhs] if isinstance(lhs, AtomicExpr) else lhs.args, f) if True in dlhs: if False not in dlhs: dlhs[False] = [1] lhs = Mul(dlhs[False]) rhs = rhs/Mul(dlhs[True]) return Eq(lhs, rhs) else: return _recursive_walk(expr) @vectorize(0) def constantsimp(expr, constants): r""" Simplifies an expression with arbitrary constants in it. This function is written specifically to work with :py:meth:`~sympy.solvers.ode.dsolve`, and is not intended for general use. Simplification is done by "absorbing" the arbitrary constants into other arbitrary constants, numbers, and symbols that they are not independent of. The symbols must all have the same name with numbers after it, for example, ``C1``, ``C2``, ``C3``. The ``symbolname`` here would be '``C``', the ``startnumber`` would be 1, and the ``endnumber`` would be 3. If the arbitrary constants are independent of the variable ``x``, then the independent symbol would be ``x``. There is no need to specify the dependent function, such as ``f(x)``, because it already has the independent symbol, ``x``, in it. Because terms are "absorbed" into arbitrary constants and because constants are renumbered after simplifying, the arbitrary constants in expr are not necessarily equal to the ones of the same name in the returned result. If two or more arbitrary constants are added, multiplied, or raised to the power of each other, they are first absorbed together into a single arbitrary constant. Then the new constant is combined into other terms if necessary. Absorption of constants is done with limited assistance: 1. terms of :py:class:`~sympy.core.add.Add`\s are collected to try join constants so `e^x (C_1 \cos(x) + C_2 \cos(x))` will simplify to `e^x C_1 \cos(x)`; 2. powers with exponents that are :py:class:`~sympy.core.add.Add`\s are expanded so `e^{C_1 + x}` will be simplified to `C_1 e^x`. Use :py:meth:`~sympy.solvers.ode.constant_renumber` to renumber constants after simplification or else arbitrary numbers on constants may appear, e.g. `C_1 + C_3 x`. In rare cases, a single constant can be "simplified" into two constants. Every differential equation solution should have as many arbitrary constants as the order of the differential equation. The result here will be technically correct, but it may, for example, have `C_1` and `C_2` in an expression, when `C_1` is actually equal to `C_2`. Use your discretion in such situations, and also take advantage of the ability to use hints in :py:meth:`~sympy.solvers.ode.dsolve`. Examples ======== >>> from sympy import symbols >>> from sympy.solvers.ode import constantsimp >>> C1, C2, C3, x, y = symbols('C1, C2, C3, x, y') >>> constantsimp(2C1x, {C1, C2, C3}) C1x >>> constantsimp(C1 + 2 + x, {C1, C2, C3}) C1 + x >>> constantsimp(C1C2 + 2 + C2 + C3x, {C1, C2, C3}) C1 + C3x """ # This function works recursively. The idea is that, for Mul, # Add, Pow, and Function, if the class has a constant in it, then # we can simplify it, which we do by recursing down and # simplifying up. Otherwise, we can skip that part of the # expression. Cs = constants orig_expr = expr constant_subexprs = _get_constant_subexpressions(expr, Cs) for xe in constant_subexprs: xes = list(xe.free_symbols) if not xes: continue if all([expr.count(c) == xe.count(c) for c in xes]): xes.sort(key=str) expr = expr.subs(xe, xes[0]) # try to perform common sub-expression elimination of constant terms try: commons, rexpr = cse(expr) commons.reverse() rexpr = rexpr[0] for s in commons: cs = list(s[1].atoms(Symbol)) if len(cs) == 1 and cs[0] in Cs and \ cs[0] not in rexpr.atoms(Symbol) and \ not any(cs[0] in ex for ex in commons if ex != s): rexpr = rexpr.subs(s[0], cs[0]) else: rexpr = rexpr.subs(s) expr = rexpr except Exception: pass expr = __remove_linear_redundancies(expr, Cs) def _conditional_term_factoring(expr): new_expr = terms_gcd(expr, clear=False, deep=True, expand=False) # we do not want to factor exponentials, so handle this separately if new_expr.is_Mul: infac = False asfac = False for m in new_expr.args: if isinstance(m, exp): asfac = True elif m.is_Add: infac = any(isinstance(fi, exp) for t in m.args for fi in Mul.make_args(t)) if asfac and infac: new_expr = expr break return new_expr expr = _conditional_term_factoring(expr) # call recursively if more simplification is possible if orig_expr != expr: return constantsimp(expr, Cs) return expr def constant_renumber(expr, symbolname, startnumber, endnumber): r""" Renumber arbitrary constants in ``expr`` to have numbers 1 through `N` where `N` is ``endnumber - startnumber + 1`` at most. In the process, this reorders expression terms in a standard way. This is a simple function that goes through and renumbers any :py:class:`~sympy.core.symbol.Symbol` with a name in the form ``symbolname + num`` where ``num`` is in the range from ``startnumber`` to ``endnumber``. Symbols are renumbered based on ``.sort_key()``, so they should be numbered roughly in the order that they appear in the final, printed expression. Note that this ordering is based in part on hashes, so it can produce different results on different machines. The structure of this function is very similar to that of :py:meth:`~sympy.solvers.ode.constantsimp`. Examples ======== >>> from sympy import symbols, Eq, pprint >>> from sympy.solvers.ode import constant_renumber >>> x, C0, C1, C2, C3, C4 = symbols('x,C:5') Only constants in the given range (inclusive) are renumbered; the renumbering always starts from 1: >>> constant_renumber(C1 + C3 + C4, 'C', 1, 3) C1 + C2 + C4 >>> constant_renumber(C0 + C1 + C3 + C4, 'C', 2, 4) C0 + 2C1 + C2 >>> constant_renumber(C0 + 2C1 + C2, 'C', 0, 1) C1 + 3C2 >>> pprint(C2 + C1x + C3x*2) 2 C1x + C2 + C3x >>> pprint(constant_renumber(C2 + C1x + C3x2, 'C', 1, 3)) 2 C1 + C2x + C3x """ if type(expr) in (set, list, tuple): return type(expr)( [constant_renumber(i, symbolname=symbolname, startnumber=startnumber, endnumber=endnumber) for i in expr] ) global newstartnumber newstartnumber = 1 constants_found = [None](endnumber + 2) constantsymbols = [Symbol( symbolname + "%d" % t) for t in range(startnumber, endnumber + 1)] # make a mapping to send all constantsymbols to S.One and use # that to make sure that term ordering is not dependent on # the indexed value of C C_1 = [(ci, S.One) for ci in constantsymbols] sort_key=lambda arg: default_sort_key(arg.subs(C_1)) def _constant_renumber(expr): r""" We need to have an internal recursive function so that newstartnumber maintains its values throughout recursive calls. """ global newstartnumber if isinstance(expr, Equality): return Eq( _constant_renumber(expr.lhs), _constant_renumber(expr.rhs)) if type(expr) not in (Mul, Add, Pow) and not expr.is_Function and \ not expr.has(constantsymbols): # Base case, as above. Hope there aren't constants inside # of some other class, because they won't be renumbered. return expr elif expr.is_Piecewise: return expr elif expr in constantsymbols: if expr not in constants_found: constants_found[newstartnumber] = expr newstartnumber += 1 return expr elif expr.is_Function or expr.is_Pow or isinstance(expr, Tuple): return expr.func( [_constant_renumber(x) for x in expr.args]) else: sortedargs = list(expr.args) sortedargs.sort(key=sort_key) return expr.func([_constant_renumber(x) for x in sortedargs]) expr = _constant_renumber(expr) # Renumbering happens here newconsts = symbols('C1:%d' % newstartnumber) expr = expr.subs(zip(constants_found[1:], newconsts), simultaneous=True) return expr def _handle_Integral(expr, func, order, hint): r""" Converts a solution with Integrals in it into an actual solution. For most hints, this simply runs ``expr.doit()``. """ global y x = func.args[0] f = func.func if hint == "1st_exact": sol = (expr.doit()).subs(y, f(x)) del y elif hint == "1st_exact_Integral": sol = Eq(Subs(expr.lhs, y, f(x)), expr.rhs) del y elif hint == "nth_linear_constant_coeff_homogeneous": sol = expr elif not hint.endswith("_Integral"): sol = expr.doit() else: sol = expr return sol # FIXME: replace the general solution in the docstring with # dsolve(equation, hint='1st_exact_Integral'). You will need to be able # to have assumptions on P and Q that dP/dy = dQ/dx. def ode_1st_exact(eq, func, order, match): r""" Solves 1st order exact ordinary differential equations. A 1st order differential equation is called exact if it is the total differential of a function. That is, the differential equation .. math:: P(x, y) \,\partial{}x + Q(x, y) \,\partial{}y = 0 is exact if there is some function `F(x, y)` such that `P(x, y) = \partial{}F/\partial{}x` and `Q(x, y) = \partial{}F/\partial{}y`. It can be shown that a necessary and sufficient condition for a first order ODE to be exact is that `\partial{}P/\partial{}y = \partial{}Q/\partial{}x`. Then, the solution will be as given below:: >>> from sympy import Function, Eq, Integral, symbols, pprint >>> x, y, t, x0, y0, C1= symbols('x,y,t,x0,y0,C1') >>> P, Q, F= map(Function, ['P', 'Q', 'F']) >>> pprint(Eq(Eq(F(x, y), Integral(P(t, y), (t, x0, x)) + ... Integral(Q(x0, t), (t, y0, y))), C1)) x y / / \| \| F(x, y) = \| P(t, y) dt + \| Q(x0, t) dt = C1 \| \| / / x0 y0 Where the first partials of `P` and `Q` exist and are continuous in a simply connected region. A note: SymPy currently has no way to represent inert substitution on an expression, so the hint ``1st_exact_Integral`` will return an integral with `dy`. This is supposed to represent the function that you are solving for. Examples ======== >>> from sympy import Function, dsolve, cos, sin >>> from sympy.abc import x >>> f = Function('f') >>> dsolve(cos(f(x)) - (xsin(f(x)) - f(x)*2)f(x).diff(x), ... f(x), hint='1st_exact') Eq(xcos(f(x)) + f(x)3/3, C1) References ========== - https://en.wikipedia.org/wiki/Exact_differential_equation - M. Tenenbaum & H. Pollard, "Ordinary Differential Equations", Dover 1963, pp. 73 # indirect doctest """ x = func.args[0] f = func.func r = match # d+ediff(f(x),x) e = r[r['e']] d = r[r['d']] global y # This is the only way to pass dummy y to _handle_Integral y = r['y'] C1 = get_numbered_constants(eq, num=1) # Refer Joel Moses, "Symbolic Integration - The Stormy Decade", # Communications of the ACM, Volume 14, Number 8, August 1971, pp. 558 # which gives the method to solve an exact differential equation. sol = Integral(d, x) + Integral((e - (Integral(d, x).diff(y))), y) return Eq(sol, C1) def ode_1st_homogeneous_coeff_best(eq, func, order, match): r""" Returns the best solution to an ODE from the two hints ``1st_homogeneous_coeff_subs_dep_div_indep`` and ``1st_homogeneous_coeff_subs_indep_div_dep``. This is as determined by :py:meth:`~sympy.solvers.ode.ode_sol_simplicity`. See the :py:meth:`~sympy.solvers.ode.ode_1st_homogeneous_coeff_subs_indep_div_dep` and :py:meth:`~sympy.solvers.ode.ode_1st_homogeneous_coeff_subs_dep_div_indep` docstrings for more information on these hints. Note that there is no ``ode_1st_homogeneous_coeff_best_Integral`` hint. Examples ======== >>> from sympy import Function, dsolve, pprint >>> from sympy.abc import x >>> f = Function('f') >>> pprint(dsolve(2xf(x) + (x2 + f(x)2)f(x).diff(x), f(x), ... hint='1st_homogeneous_coeff_best', simplify=False)) / 2 \ \| 3x \| log\|----- + 1\| \| 2 \| \f (x) / log(f(x)) = log(C1) - -------------- 3 References ========== - https://en.wikipedia.org/wiki/Homogeneous_differential_equation - M. Tenenbaum & H. Pollard, "Ordinary Differential Equations", Dover 1963, pp. 59 # indirect doctest """ # There are two substitutions that solve the equation, u1=y/x and u2=x/y # They produce different integrals, so try them both and see which # one is easier. sol1 = ode_1st_homogeneous_coeff_subs_indep_div_dep(eq, func, order, match) sol2 = ode_1st_homogeneous_coeff_subs_dep_div_indep(eq, func, order, match) simplify = match.get('simplify', True) if simplify: # why is odesimp called here? Should it be at the usual spot? constants = sol1.free_symbols.difference(eq.free_symbols) sol1 = odesimp( sol1, func, order, constants, "1st_homogeneous_coeff_subs_indep_div_dep") constants = sol2.free_symbols.difference(eq.free_symbols) sol2 = odesimp( sol2, func, order, constants, "1st_homogeneous_coeff_subs_dep_div_indep") return min([sol1, sol2], key=lambda x: ode_sol_simplicity(x, func, trysolving=not simplify)) def ode_1st_homogeneous_coeff_subs_dep_div_indep(eq, func, order, match): r""" Solves a 1st order differential equation with homogeneous coefficients using the substitution `u_1 = \frac{\text{<dependent variable>}}{\text{<independent variable>}}`. This is a differential equation .. math:: P(x, y) + Q(x, y) dy/dx = 0 such that `P` and `Q` are homogeneous and of the same order. A function `F(x, y)` is homogeneous of order `n` if `F(x t, y t) = t^n F(x, y)`. Equivalently, `F(x, y)` can be rewritten as `G(y/x)` or `H(x/y)`. See also the docstring of :py:meth:`~sympy.solvers.ode.homogeneous_order`. If the coefficients `P` and `Q` in the differential equation above are homogeneous functions of the same order, then it can be shown that the substitution `y = u_1 x` (i.e. `u_1 = y/x`) will turn the differential equation into an equation separable in the variables `x` and `u`. If `h(u_1)` is the function that results from making the substitution `u_1 = f(x)/x` on `P(x, f(x))` and `g(u_2)` is the function that results from the substitution on `Q(x, f(x))` in the differential equation `P(x, f(x)) + Q(x, f(x)) f'(x) = 0`, then the general solution is:: >>> from sympy import Function, dsolve, pprint >>> from sympy.abc import x >>> f, g, h = map(Function, ['f', 'g', 'h']) >>> genform = g(f(x)/x) + h(f(x)/x)f(x).diff(x) >>> pprint(genform) /f(x)\ /f(x)\ d g\|----\| + h\|----\|--(f(x)) \ x / \ x / dx >>> pprint(dsolve(genform, f(x), ... hint='1st_homogeneous_coeff_subs_dep_div_indep_Integral')) f(x) ---- x / \| \| -h(u1) log(x) = C1 + \| ---------------- d(u1) \| u1h(u1) + g(u1) \| / Where `u_1 h(u_1) + g(u_1) \ne 0` and `x \ne 0`. See also the docstrings of :py:meth:`~sympy.solvers.ode.ode_1st_homogeneous_coeff_best` and :py:meth:`~sympy.solvers.ode.ode_1st_homogeneous_coeff_subs_indep_div_dep`. Examples ======== >>> from sympy import Function, dsolve >>> from sympy.abc import x >>> f = Function('f') >>> pprint(dsolve(2xf(x) + (x2 + f(x)2)f(x).diff(x), f(x), ... hint='1st_homogeneous_coeff_subs_dep_div_indep', simplify=False)) / 3 \ \|3f(x) f (x)\| log\|------ + -----\| \| x 3 \| \ x / log(x) = log(C1) - ------------------- 3 References ========== - https://en.wikipedia.org/wiki/Homogeneous_differential_equation - M. Tenenbaum & H. Pollard, "Ordinary Differential Equations", Dover 1963, pp. 59 # indirect doctest """ x = func.args[0] f = func.func u = Dummy('u') u1 = Dummy('u1') # u1 == f(x)/x r = match # d+ediff(f(x),x) C1 = get_numbered_constants(eq, num=1) xarg = match.get('xarg', 0) yarg = match.get('yarg', 0) int = Integral( (-r[r['e']]/(r[r['d']] + u1r[r['e']])).subs({x: 1, r['y']: u1}), (u1, None, f(x)/x)) sol = logcombine(Eq(log(x), int + log(C1)), force=True) sol = sol.subs(f(x), u).subs(((u, u - yarg), (x, x - xarg), (u, f(x)))) return sol def ode_1st_homogeneous_coeff_subs_indep_div_dep(eq, func, order, match): r""" Solves a 1st order differential equation with homogeneous coefficients using the substitution `u_2 = \frac{\text{<independent variable>}}{\text{<dependent variable>}}`. This is a differential equation .. math:: P(x, y) + Q(x, y) dy/dx = 0 such that `P` and `Q` are homogeneous and of the same order. A function `F(x, y)` is homogeneous of order `n` if `F(x t, y t) = t^n F(x, y)`. Equivalently, `F(x, y)` can be rewritten as `G(y/x)` or `H(x/y)`. See also the docstring of :py:meth:`~sympy.solvers.ode.homogeneous_order`. If the coefficients `P` and `Q` in the differential equation above are homogeneous functions of the same order, then it can be shown that the substitution `x = u_2 y` (i.e. `u_2 = x/y`) will turn the differential equation into an equation separable in the variables `y` and `u_2`. If `h(u_2)` is the function that results from making the substitution `u_2 = x/f(x)` on `P(x, f(x))` and `g(u_2)` is the function that results from the substitution on `Q(x, f(x))` in the differential equation `P(x, f(x)) + Q(x, f(x)) f'(x) = 0`, then the general solution is: >>> from sympy import Function, dsolve, pprint >>> from sympy.abc import x >>> f, g, h = map(Function, ['f', 'g', 'h']) >>> genform = g(x/f(x)) + h(x/f(x))f(x).diff(x) >>> pprint(genform) / x \ / x \ d g\|----\| + h\|----\|--(f(x)) \f(x)/ \f(x)/ dx >>> pprint(dsolve(genform, f(x), ... hint='1st_homogeneous_coeff_subs_indep_div_dep_Integral')) x ---- f(x) / \| \| -g(u2) \| ---------------- d(u2) \| u2g(u2) + h(u2) \| / <BLANKLINE> f(x) = C1e Where `u_2 g(u_2) + h(u_2) \ne 0` and `f(x) \ne 0`. See also the docstrings of :py:meth:`~sympy.solvers.ode.ode_1st_homogeneous_coeff_best` and :py:meth:`~sympy.solvers.ode.ode_1st_homogeneous_coeff_subs_dep_div_indep`. Examples ======== >>> from sympy import Function, pprint, dsolve >>> from sympy.abc import x >>> f = Function('f') >>> pprint(dsolve(2xf(x) + (x2 + f(x)2)f(x).diff(x), f(x), ... hint='1st_homogeneous_coeff_subs_indep_div_dep', ... simplify=False)) / 2 \ \| 3x \| log\|----- + 1\| \| 2 \| \f (x) / log(f(x)) = log(C1) - -------------- 3 References ========== - https://en.wikipedia.org/wiki/Homogeneous_differential_equation - M. Tenenbaum & H. Pollard, "Ordinary Differential Equations", Dover 1963, pp. 59 # indirect doctest """ x = func.args[0] f = func.func u = Dummy('u') u2 = Dummy('u2') # u2 == x/f(x) r = match # d+ediff(f(x),x) C1 = get_numbered_constants(eq, num=1) xarg = match.get('xarg', 0) # If xarg present take xarg, else zero yarg = match.get('yarg', 0) # If yarg present take yarg, else zero int = Integral( simplify( (-r[r['d']]/(r[r['e']] + u2r[r['d']])).subs({x: u2, r['y']: 1})), (u2, None, x/f(x))) sol = logcombine(Eq(log(f(x)), int + log(C1)), force=True) sol = sol.subs(f(x), u).subs(((u, u - yarg), (x, x - xarg), (u, f(x)))) return sol # XXX: Should this function maybe go somewhere else? def homogeneous_order(eq, symbols): r""" Returns the order `n` if `g` is homogeneous and ``None`` if it is not homogeneous. Determines if a function is homogeneous and if so of what order. A function `f(x, y, \cdots)` is homogeneous of order `n` if `f(t x, t y, \cdots) = t^n f(x, y, \cdots)`. If the function is of two variables, `F(x, y)`, then `f` being homogeneous of any order is equivalent to being able to rewrite `F(x, y)` as `G(x/y)` or `H(y/x)`. This fact is used to solve 1st order ordinary differential equations whose coefficients are homogeneous of the same order (see the docstrings of :py:meth:`~solvers.ode.ode_1st_homogeneous_coeff_subs_dep_div_indep` and :py:meth:`~solvers.ode.ode_1st_homogeneous_coeff_subs_indep_div_dep`). Symbols can be functions, but every argument of the function must be a symbol, and the arguments of the function that appear in the expression must match those given in the list of symbols. If a declared function appears with different arguments than given in the list of symbols, ``None`` is returned. Examples ======== >>> from sympy import Function, homogeneous_order, sqrt >>> from sympy.abc import x, y >>> f = Function('f') >>> homogeneous_order(f(x), f(x)) is None True >>> homogeneous_order(f(x,y), f(y, x), x, y) is None True >>> homogeneous_order(f(x), f(x), x) 1 >>> homogeneous_order(x*2f(x)/sqrt(x2+f(x)2), x, f(x)) 2 >>> homogeneous_order(x*2+f(x), x, f(x)) is None True """ if not symbols: raise ValueError("homogeneous_order: no symbols were given.") symset = set(symbols) eq = sympify(eq) # The following are not supported if eq.has(Order, Derivative): return None # These are all constants if (eq.is_Number or eq.is_NumberSymbol or eq.is_number ): return S.Zero # Replace all functions with dummy variables dum = numbered_symbols(prefix='d', cls=Dummy) newsyms = set() for i in [j for j in symset if getattr(j, 'is_Function')]: iargs = set(i.args) if iargs.difference(symset): return None else: dummyvar = next(dum) eq = eq.subs(i, dummyvar) symset.remove(i) newsyms.add(dummyvar) symset.update(newsyms) if not eq.free_symbols & symset: return None # assuming order of a nested function can only be equal to zero if isinstance(eq, Function): return None if homogeneous_order( eq.args[0], tuple(symset)) != 0 else S.Zero # make the replacement of x with xt and see if t can be factored out t = Dummy('t', positive=True) # It is sufficient that t > 0 eqs = separatevars(eq.subs([(i, ti) for i in symset]), [t], dict=True)[t] if eqs is S.One: return S.Zero # there was no term with only t i, d = eqs.as_independent(t, as_Add=False) b, e = d.as_base_exp() if b == t: return e def ode_1st_linear(eq, func, order, match): r""" Solves 1st order linear differential equations. These are differential equations of the form .. math:: dy/dx + P(x) y = Q(x)\text{.} These kinds of differential equations can be solved in a general way. The integrating factor `e^{\int P(x) \,dx}` will turn the equation into a separable equation. The general solution is:: >>> from sympy import Function, dsolve, Eq, pprint, diff, sin >>> from sympy.abc import x >>> f, P, Q = map(Function, ['f', 'P', 'Q']) >>> genform = Eq(f(x).diff(x) + P(x)f(x), Q(x)) >>> pprint(genform) d P(x)f(x) + --(f(x)) = Q(x) dx >>> pprint(dsolve(genform, f(x), hint='1st_linear_Integral')) / / \ \| \| \| \| \| / \| / \| \| \| \| \| \| \| \| P(x) dx \| - \| P(x) dx \| \| \| \| \| \| \| / \| / f(x) = \|C1 + \| Q(x)e dx\|e \| \| \| \ / / Examples ======== >>> f = Function('f') >>> pprint(dsolve(Eq(xdiff(f(x), x) - f(x), x2sin(x)), ... f(x), '1st_linear')) f(x) = x(C1 - cos(x)) References ========== - https://en.wikipedia.org/wiki/Linear_differential_equation#First_order_equation - M. Tenenbaum & H. Pollard, "Ordinary Differential Equations", Dover 1963, pp. 92 # indirect doctest """ x = func.args[0] f = func.func r = match # adiff(f(x),x) + bf(x) + c C1 = get_numbered_constants(eq, num=1) t = exp(Integral(r[r['b']]/r[r['a']], x)) tt = Integral(t(-r[r['c']]/r[r['a']]), x) f = match.get('u', f(x)) # take almost-linear u if present, else f(x) return Eq(f, (tt + C1)/t) def ode_Bernoulli(eq, func, order, match): r""" Solves Bernoulli differential equations. These are equations of the form .. math:: dy/dx + P(x) y = Q(x) y^n\text{, }n \ne 1`\text{.} The substitution `w = 1/y^{1-n}` will transform an equation of this form into one that is linear (see the docstring of :py:meth:`~sympy.solvers.ode.ode_1st_linear`). The general solution is:: >>> from sympy import Function, dsolve, Eq, pprint >>> from sympy.abc import x, n >>> f, P, Q = map(Function, ['f', 'P', 'Q']) >>> genform = Eq(f(x).diff(x) + P(x)f(x), Q(x)f(x)*n) >>> pprint(genform) d n P(x)f(x) + --(f(x)) = Q(x)f (x) dx >>> pprint(dsolve(genform, f(x), hint='Bernoulli_Integral')) #doctest: +SKIP 1 ---- 1 - n // / \ \ \|\| \| \| \| \|\| \| / \| / \| \|\| \| \| \| \| \| \|\| \| (1 - n) \| P(x) dx \| (-1 + n)* \| P(x) dx\| \|\| \| \| \| \| \| \|\| \| / \| / \| f(x) = \|\|C1 + (-1 + n)* \| -Q(x)e dx\|e \| \|\| \| \| \| \\ / / / Note that the equation is separable when `n = 1` (see the docstring of :py:meth:`~sympy.solvers.ode.ode_separable`). >>> pprint(dsolve(Eq(f(x).diff(x) + P(x)f(x), Q(x)f(x)), f(x), ... hint='separable_Integral')) f(x) / \| / \| 1 \| \| - dy = C1 + \| (-P(x) + Q(x)) dx \| y \| \| / / Examples ======== >>> from sympy import Function, dsolve, Eq, pprint, log >>> from sympy.abc import x >>> f = Function('f') >>> pprint(dsolve(Eq(xf(x).diff(x) + f(x), log(x)f(x)*2), ... f(x), hint='Bernoulli')) 1 f(x) = ------------------- / log(x) 1\ x\|C1 + ------ + -\| \ x x/ References ========== - https://en.wikipedia.org/wiki/Bernoulli_differential_equation - M. Tenenbaum & H. Pollard, "Ordinary Differential Equations", Dover 1963, pp. 95 # indirect doctest """ x = func.args[0] f = func.func r = match # adiff(f(x),x) + bf(x) + cf(x)n, n != 1 C1 = get_numbered_constants(eq, num=1) t = exp((1 - r[r['n']])Integral(r[r['b']]/r[r['a']], x)) tt = (r[r['n']] - 1)Integral(tr[r['c']]/r[r['a']], x) return Eq(f(x), ((tt + C1)/t)*(1/(1 - r[r['n']]))) def ode_Riccati_special_minus2(eq, func, order, match): r""" The general Riccati equation has the form .. math:: dy/dx = f(x) y^2 + g(x) y + h(x)\text{.} While it does not have a general solution [1], the "special" form, `dy/dx = a y^2 - b x^c`, does have solutions in many cases [2]. This routine returns a solution for `a(dy/dx) = b y^2 + c y/x + d/x^2` that is obtained by using a suitable change of variables to reduce it to the special form and is valid when neither `a` nor `b` are zero and either `c` or `d` is zero. >>> from sympy.abc import x, y, a, b, c, d >>> from sympy.solvers.ode import dsolve, checkodesol >>> from sympy import pprint, Function >>> f = Function('f') >>> y = f(x) >>> genform = ay.diff(x) - (by2 + cy/x + d/x*2) >>> sol = dsolve(genform, y) >>> pprint(sol, wrap_line=False) / / __________________ \\ \| __________________ \| / 2 \|\| \| / 2 \| \/ 4bd - (a + c) log(x)\|\| -\|a + c - \/ 4bd - (a + c) tan\|C1 + ----------------------------\|\| \ \ 2a // f(x) = ------------------------------------------------------------------------ 2bx >>> checkodesol(genform, sol, order=1)[0] True References ========== 1. http://www.maplesoft.com/support/help/Maple/view.aspx?path=odeadvisor/Riccati 2. http://eqworld.ipmnet.ru/en/solutions/ode/ode0106.pdf - http://eqworld.ipmnet.ru/en/solutions/ode/ode0123.pdf """ x = func.args[0] f = func.func r = match # a2diff(f(x),x) + b2f(x) + c2f(x)/x + d2/x2 a2, b2, c2, d2 = [r[r[s]] for s in 'a2 b2 c2 d2'.split()] C1 = get_numbered_constants(eq, num=1) mu = sqrt(4d2b2 - (a2 - c2)2) return Eq(f(x), (a2 - c2 - mutan(mu/(2a2)log(x) + C1))/(2b2x)) def ode_Liouville(eq, func, order, match): r""" Solves 2nd order Liouville differential equations. The general form of a Liouville ODE is .. math:: \frac{d^2 y}{dx^2} + g(y) \left(\! \frac{dy}{dx}\!\right)^2 + h(x) \frac{dy}{dx}\text{.} The general solution is: >>> from sympy import Function, dsolve, Eq, pprint, diff >>> from sympy.abc import x >>> f, g, h = map(Function, ['f', 'g', 'h']) >>> genform = Eq(diff(f(x),x,x) + g(f(x))diff(f(x),x)2 + ... h(x)diff(f(x),x), 0) >>> pprint(genform) 2 2 /d \ d d g(f(x))\|--(f(x))\| + h(x)--(f(x)) + ---(f(x)) = 0 \dx / dx 2 dx >>> pprint(dsolve(genform, f(x), hint='Liouville_Integral')) f(x) / / \| \| \| / \| / \| \| \| \| \| - \| h(x) dx \| \| g(y) dy \| \| \| \| \| / \| / C1 + C2* \| e dx + \| e dy = 0 \| \| / / Examples ======== >>> from sympy import Function, dsolve, Eq, pprint >>> from sympy.abc import x >>> f = Function('f') >>> pprint(dsolve(diff(f(x), x, x) + diff(f(x), x)*2/f(x) + ... diff(f(x), x)/x, f(x), hint='Liouville')) ________________ ________________ [f(x) = -\/ C1 + C2log(x) , f(x) = \/ C1 + C2log(x) ] References ========== - Goldstein and Braun, "Advanced Methods for the Solution of Differential Equations", pp. 98 - http://www.maplesoft.com/support/help/Maple/view.aspx?path=odeadvisor/Liouville # indirect doctest """ # Liouville ODE: # f(x).diff(x, 2) + g(f(x))(f(x).diff(x, 2))*2 + h(x)f(x).diff(x) # See Goldstein and Braun, "Advanced Methods for the Solution of # Differential Equations", pg. 98, as well as # http://www.maplesoft.com/support/help/view.aspx?path=odeadvisor/Liouville x = func.args[0] f = func.func r = match # f(x).diff(x, 2) + gf(x).diff(x)2 + hf(x).diff(x) y = r['y'] C1, C2 = get_numbered_constants(eq, num=2) int = Integral(exp(Integral(r['g'], y)), (y, None, f(x))) sol = Eq(int + C1Integral(exp(-Integral(r['h'], x)), x) + C2, 0) return sol def ode_2nd_power_series_ordinary(eq, func, order, match): r""" Gives a power series solution to a second order homogeneous differential equation with polynomial coefficients at an ordinary point. A homogenous differential equation is of the form .. math :: P(x)\frac{d^2y}{dx^2} + Q(x)\frac{dy}{dx} + R(x) = 0 For simplicity it is assumed that `P(x)`, `Q(x)` and `R(x)` are polynomials, it is sufficient that `\frac{Q(x)}{P(x)}` and `\frac{R(x)}{P(x)}` exists at `x_{0}`. A recurrence relation is obtained by substituting `y` as `\sum_{n=0}^\infty a_{n}x^{n}`, in the differential equation, and equating the nth term. Using this relation various terms can be generated. Examples ======== >>> from sympy import dsolve, Function, pprint >>> from sympy.abc import x, y >>> f = Function("f") >>> eq = f(x).diff(x, 2) + f(x) >>> pprint(dsolve(eq, hint='2nd_power_series_ordinary')) / 4 2 \ / 2 \ \|x x \| \| x \| / 6\ f(x) = C2\|-- - -- + 1\| + C1x\|- -- + 1\| + O\x / \24 2 / \ 6 / References ========== - http://tutorial.math.lamar.edu/Classes/DE/SeriesSolutions.aspx - George E. Simmons, "Differential Equations with Applications and Historical Notes", p.p 176 - 184 """ x = func.args[0] f = func.func C0, C1 = get_numbered_constants(eq, num=2) n = Dummy("n", integer=True) s = Wild("s") k = Wild("k", exclude=[x]) x0 = match.get('x0') terms = match.get('terms', 5) p = match[match['a3']] q = match[match['b3']] r = match[match['c3']] seriesdict = {} recurr = Function("r") # Generating the recurrence relation which works this way: # for the second order term the summation begins at n = 2. The coefficients # p is multiplied with an(n - 1)(n - 2)xn-2 and a substitution is made such that # the exponent of x becomes n. # For example, if p is x, then the second degree recurrence term is # an(n - 1)(n - 2)x*n-1, substituting (n - 1) as n, it transforms to # an+1n(n - 1)x*n. # A similar process is done with the first order and zeroth order term. coefflist = [(recurr(n), r), (nrecurr(n), q), (n(n - 1)recurr(n), p)] for index, coeff in enumerate(coefflist): if coeff[1]: f2 = powsimp(expand((coeff[1](x - x0)(n - index)).subs(x, x + x0))) if f2.is_Add: addargs = f2.args else: addargs = [f2] for arg in addargs: powm = arg.match(sx*k) term = coeff[0]powm[s] if not powm[k].is_Symbol: term = term.subs(n, n - powm[k].as_independent(n)[0]) startind = powm[k].subs(n, index) # Seeing if the startterm can be reduced further. # If it vanishes for n lesser than startind, it is # equal to summation from n. if startind: for i in reversed(range(startind)): if not term.subs(n, i): seriesdict[term] = i else: seriesdict[term] = i + 1 break else: seriesdict[term] = S(0) # Stripping of terms so that the sum starts with the same number. teq = S(0) suminit = seriesdict.values() rkeys = seriesdict.keys() req = Add(rkeys) if any(suminit): maxval = max(suminit) for term in seriesdict: val = seriesdict[term] if val != maxval: for i in range(val, maxval): teq += term.subs(n, val) finaldict = {} if teq: fargs = teq.atoms(AppliedUndef) if len(fargs) == 1: finaldict[fargs.pop()] = 0 else: maxf = max(fargs, key = lambda x: x.args[0]) sol = solve(teq, maxf) if isinstance(sol, list): sol = sol[0] finaldict[maxf] = sol # Finding the recurrence relation in terms of the largest term. fargs = req.atoms(AppliedUndef) maxf = max(fargs, key = lambda x: x.args[0]) minf = min(fargs, key = lambda x: x.args[0]) if minf.args[0].is_Symbol: startiter = 0 else: startiter = -minf.args[0].as_independent(n)[0] lhs = maxf rhs = solve(req, maxf) if isinstance(rhs, list): rhs = rhs[0] # Checking how many values are already present tcounter = len([t for t in finaldict.values() if t]) for _ in range(tcounter, terms - 3): # Assuming c0 and c1 to be arbitrary check = rhs.subs(n, startiter) nlhs = lhs.subs(n, startiter) nrhs = check.subs(finaldict) finaldict[nlhs] = nrhs startiter += 1 # Post processing series = C0 + C1(x - x0) for term in finaldict: if finaldict[term]: fact = term.args[0] series += (finaldict[term].subs([(recurr(0), C0), (recurr(1), C1)])( x - x0)fact) series = collect(expand_mul(series), [C0, C1]) + Order(xterms) return Eq(f(x), series) def ode_2nd_power_series_regular(eq, func, order, match): r""" Gives a power series solution to a second order homogeneous differential equation with polynomial coefficients at a regular point. A second order homogenous differential equation is of the form .. math :: P(x)\frac{d^2y}{dx^2} + Q(x)\frac{dy}{dx} + R(x) = 0 A point is said to regular singular at `x0` if `x - x0\frac{Q(x)}{P(x)}` and `(x - x0)^{2}\frac{R(x)}{P(x)}` are analytic at `x0`. For simplicity `P(x)`, `Q(x)` and `R(x)` are assumed to be polynomials. The algorithm for finding the power series solutions is: 1. Try expressing `(x - x0)P(x)` and `((x - x0)^{2})Q(x)` as power series solutions about x0. Find `p0` and `q0` which are the constants of the power series expansions. 2. Solve the indicial equation `f(m) = m(m - 1) + mp0 + q0`, to obtain the roots `m1` and `m2` of the indicial equation. 3. If `m1 - m2` is a non integer there exists two series solutions. If `m1 = m2`, there exists only one solution. If `m1 - m2` is an integer, then the existence of one solution is confirmed. The other solution may or may not exist. The power series solution is of the form `x^{m}\sum_{n=0}^\infty a_{n}x^{n}`. The coefficients are determined by the following recurrence relation. `a_{n} = -\frac{\sum_{k=0}^{n-1} q_{n-k} + (m + k)p_{n-k}}{f(m + n)}`. For the case in which `m1 - m2` is an integer, it can be seen from the recurrence relation that for the lower root `m`, when `n` equals the difference of both the roots, the denominator becomes zero. So if the numerator is not equal to zero, a second series solution exists. Examples ======== >>> from sympy import dsolve, Function, pprint >>> from sympy.abc import x, y >>> f = Function("f") >>> eq = x(f(x).diff(x, 2)) + 2(f(x).diff(x)) + xf(x) >>> pprint(dsolve(eq)) / 6 4 2 \ \| x x x \| / 4 2 \ C1\|- --- + -- - -- + 1\| \| x x \| \ 720 24 2 / / 6\ f(x) = C2\|--- - -- + 1\| + ------------------------ + O\x / \120 6 / x References ========== - George E. Simmons, "Differential Equations with Applications and Historical Notes", p.p 176 - 184 """ x = func.args[0] f = func.func C0, C1 = get_numbered_constants(eq, num=2) n = Dummy("n") m = Dummy("m") # for solving the indicial equation s = Wild("s") k = Wild("k", exclude=[x]) x0 = match.get('x0') terms = match.get('terms', 5) p = match['p'] q = match['q'] # Generating the indicial equation indicial = [] for term in [p, q]: if not term.has(x): indicial.append(term) else: term = series(term, n=1, x0=x0) if isinstance(term, Order): indicial.append(S(0)) else: for arg in term.args: if not arg.has(x): indicial.append(arg) break p0, q0 = indicial sollist = solve(m(m - 1) + mp0 + q0, m) if sollist and isinstance(sollist, list) and all( [sol.is_real for sol in sollist]): serdict1 = {} serdict2 = {} if len(sollist) == 1: # Only one series solution exists in this case. m1 = m2 = sollist.pop() if terms-m1-1 <= 0: return Eq(f(x), Order(terms)) serdict1 = _frobenius(terms-m1-1, m1, p0, q0, p, q, x0, x, C0) else: m1 = sollist[0] m2 = sollist[1] if m1 < m2: m1, m2 = m2, m1 # Irrespective of whether m1 - m2 is an integer or not, one # Frobenius series solution exists. serdict1 = _frobenius(terms-m1-1, m1, p0, q0, p, q, x0, x, C0) if not (m1 - m2).is_integer: # Second frobenius series solution exists. serdict2 = _frobenius(terms-m2-1, m2, p0, q0, p, q, x0, x, C1) else: # Check if second frobenius series solution exists. serdict2 = _frobenius(terms-m2-1, m2, p0, q0, p, q, x0, x, C1, check=m1) if serdict1: finalseries1 = C0 for key in serdict1: power = int(key.name[1:]) finalseries1 += serdict1[key](x - x0)power finalseries1 = (x - x0)m1finalseries1 finalseries2 = S(0) if serdict2: for key in serdict2: power = int(key.name[1:]) finalseries2 += serdict2[key](x - x0)power finalseries2 += C1 finalseries2 = (x - x0)m2finalseries2 return Eq(f(x), collect(finalseries1 + finalseries2, [C0, C1]) + Order(xterms)) def _frobenius(n, m, p0, q0, p, q, x0, x, c, check=None): r""" Returns a dict with keys as coefficients and values as their values in terms of C0 """ n = int(n) # In cases where m1 - m2 is not an integer m2 = check d = Dummy("d") numsyms = numbered_symbols("C", start=0) numsyms = [next(numsyms) for i in range(n + 1)] C0 = Symbol("C0") serlist = [] for ser in [p, q]: # Order term not present if ser.is_polynomial(x) and Poly(ser, x).degree() <= n: if x0: ser = ser.subs(x, x + x0) dict_ = Poly(ser, x).as_dict() # Order term present else: tseries = series(ser, x=x0, n=n+1) # Removing order dict_ = Poly(list(ordered(tseries.args))[: -1], x).as_dict() # Fill in with zeros, if coefficients are zero. for i in range(n + 1): if (i,) not in dict_: dict_[(i,)] = S(0) serlist.append(dict_) pseries = serlist[0] qseries = serlist[1] indicial = d(d - 1) + dp0 + q0 frobdict = {} for i in range(1, n + 1): num = c(mpseries[(i,)] + qseries[(i,)]) for j in range(1, i): sym = Symbol("C" + str(j)) num += frobdict[sym]((m + j)pseries[(i - j,)] + qseries[(i - j,)]) # Checking for cases when m1 - m2 is an integer. If num equals zero # then a second Frobenius series solution cannot be found. If num is not zero # then set constant as zero and proceed. if m2 is not None and i == m2 - m: if num: return False else: frobdict[numsyms[i]] = S(0) else: frobdict[numsyms[i]] = -num/(indicial.subs(d, m+i)) return frobdict def _nth_algebraic_match(eq, func): r""" Matches any differential equation that nth_algebraic can solve. Uses `sympy.solve` but teaches it how to integrate derivatives. This involves calling `sympy.solve` and does most of the work of finding a solution (apart from evaluating the integrals). """ # Each integration should generate a different constant constants = iter(numbered_symbols(prefix='C', cls=Symbol, start=1)) constant = lambda: next(constants, None) # Like Derivative but "invertible" class diffx(Function): def inverse(self): # We mustn't use integrate here because fx has been replaced by _t # in the equation so integrals will not be correct while solve is # still working. return lambda expr: Integral(expr, var) + constant() # Replace derivatives wrt the independent variable with diffx def replace(eq, var): def expand_diffx(args): differand, diffs = args[0], args[1:] toreplace = differand for v, n in diffs: for _ in range(n): if v == var: toreplace = diffx(toreplace) else: toreplace = Derivative(toreplace, v) return toreplace return eq.replace(Derivative, expand_diffx) # Restore derivatives in solution afterwards def unreplace(eq, var): return eq.replace(diffx, lambda e: Derivative(e, var)) # The independent variable var = func.args[0] subs_eqn = replace(eq, var) try: solns = solve(subs_eqn, func) except NotImplementedError: solns = [] solns = [unreplace(soln, var) for soln in solns] solns = [Equality(func, soln) for soln in solns] return {'var':var, 'solutions':solns} def ode_nth_algebraic(eq, func, order, match): r""" Solves an `n`\th order ordinary differential equation using algebra and integrals. There is no general form for the kind of equation that this can solve. The the equation is solved algebraically treating differentiation as an invertible algebraic function. Examples ======== >>> from sympy import Function, dsolve, Eq >>> from sympy.abc import x >>> f = Function('f') >>> eq = Eq(f(x) * (f(x).diff(x)*2 - 1), 0) >>> dsolve(eq, f(x), hint='nth_algebraic') ... # doctest: +NORMALIZE_WHITESPACE [Eq(f(x), 0), Eq(f(x), C1 - x), Eq(f(x), C1 + x)] Note that this solver can return algebraic solutions that do not have any integration constants (f(x) = 0 in the above example). # indirect doctest """ solns = match['solutions'] var = match['var'] solns = _nth_algebraic_remove_redundant_solutions(eq, solns, order, var) if len(solns) == 1: return solns[0] else: return solns # FIXME: Maybe something like this function should be applied to the solutions # returned by dsolve in general rather than just for nth_algebraic... def _nth_algebraic_remove_redundant_solutions(eq, solns, order, var): r""" Remove redundant solutions from the set of solutions returned by nth_algebraic. This function is needed because otherwise nth_algebraic can return redundant solutions where both algebraic solutions and integral solutions are found to the ODE. As an example consider: eq = Eq(f(x) f(x).diff(x), 0) There are two ways to find solutions to eq. The first is the algebraic solution f(x)=0. The second is to solve the equation f(x).diff(x) = 0 leading to the solution f(x) = C1. In this particular case we then see that the first solution is a special case of the second and we don't want to return it. This does not always happen for algebraic solutions though since if we have eq = Eq(f(x)(1 + f(x).diff(x)), 0) then we get the algebraic solution f(x) = 0 and the integral solution f(x) = -x + C1 and in this case the two solutions are not equivalent wrt initial conditions so both should be returned. """ def is_special_case_of(soln1, soln2): return _nth_algebraic_is_special_case_of(soln1, soln2, eq, order, var) unique_solns = [] for soln1 in solns: for soln2 in unique_solns[:]: if is_special_case_of(soln1, soln2): break elif is_special_case_of(soln2, soln1): unique_solns.remove(soln2) else: unique_solns.append(soln1) return unique_solns def _nth_algebraic_is_special_case_of(soln1, soln2, eq, order, var): r""" True if soln1 is found to be a special case of soln2 wrt some value of the constants that appear in soln2. False otherwise. """ # The solutions returned by nth_algebraic should be given explicitly as in # Eq(f(x), expr). We will equate the RHSs of the two solutions giving an # equation f1(x) = f2(x). # # Since this is supposed to hold for all x it also holds for derivatives # f1'(x) and f2'(x). For an order n ode we should be able to differentiate # each solution n times to get n+1 equations. # # We then try to solve those n+1 equations for the integrations constants # in f2(x). If we can find a solution that doesn't depend on x then it # means that some value of the constants in f1(x) is a special case of # f2(x) corresponding to a paritcular choice of the integration constants. constants1 = soln1.free_symbols.difference(eq.free_symbols) constants2 = soln2.free_symbols.difference(eq.free_symbols) constants1_new = get_numbered_constants(soln1.rhs - soln2.rhs, len(constants1)) if len(constants1) == 1: constants1_new = {constants1_new} for c_old, c_new in zip(constants1, constants1_new): soln1 = soln1.subs(c_old, c_new) # n equations for f1(x)=f2(x), f1'(x)=f2'(x), ... lhs = soln1.rhs.doit() rhs = soln2.rhs.doit() eqns = [Eq(lhs, rhs)] for n in range(1, order): lhs = lhs.diff(var) rhs = rhs.diff(var) eq = Eq(lhs, rhs) eqns.append(eq) # BooleanTrue/False awkwardly show up for trivial equations if any(isinstance(eq, BooleanFalse) for eq in eqns): return False eqns = [eq for eq in eqns if not isinstance(eq, BooleanTrue)] constant_solns = solve(eqns, constants2) # Sometimes returns a dict and sometimes a list of dicts if isinstance(constant_solns, dict): constant_solns = [constant_solns] # If any solution gives all constants as expressions that don't depend on # x then there exists constants for soln2 that give soln1 for constant_soln in constant_solns: if not any(c.has(var) for c in constant_soln.values()): return True else: return False def _nth_linear_match(eq, func, order): r""" Matches a differential equation to the linear form: .. math:: a_n(x) y^{(n)} + \cdots + a_1(x)y' + a_0(x) y + B(x) = 0 Returns a dict of order:coeff terms, where order is the order of the derivative on each term, and coeff is the coefficient of that derivative. The key ``-1`` holds the function `B(x)`. Returns ``None`` if the ODE is not linear. This function assumes that ``func`` has already been checked to be good. Examples ======== >>> from sympy import Function, cos, sin >>> from sympy.abc import x >>> from sympy.solvers.ode import _nth_linear_match >>> f = Function('f') >>> _nth_linear_match(f(x).diff(x, 3) + 2f(x).diff(x) + ... xf(x).diff(x, 2) + cos(x)f(x).diff(x) + x - f(x) - ... sin(x), f(x), 3) {-1: x - sin(x), 0: -1, 1: cos(x) + 2, 2: x, 3: 1} >>> _nth_linear_match(f(x).diff(x, 3) + 2f(x).diff(x) + ... xf(x).diff(x, 2) + cos(x)f(x).diff(x) + x - f(x) - ... sin(f(x)), f(x), 3) == None True """ x = func.args[0] one_x = {x} terms = {i: S.Zero for i in range(-1, order + 1)} for i in Add.make_args(eq): if not i.has(func): terms[-1] += i else: c, f = i.as_independent(func) if (isinstance(f, Derivative) and set(f.variables) == one_x and f.args[0] == func): terms[f.derivative_count] += c elif f == func: terms[len(f.args[1:])] += c else: return None return terms def ode_nth_linear_euler_eq_homogeneous(eq, func, order, match, returns='sol'): r""" Solves an `n`\th order linear homogeneous variable-coefficient Cauchy-Euler equidimensional ordinary differential equation. This is an equation with form `0 = a_0 f(x) + a_1 x f'(x) + a_2 x^2 f''(x) \cdots`. These equations can be solved in a general manner, by substituting solutions of the form `f(x) = x^r`, and deriving a characteristic equation for `r`. When there are repeated roots, we include extra terms of the form `C_{r k} \ln^k(x) x^r`, where `C_{r k}` is an arbitrary integration constant, `r` is a root of the characteristic equation, and `k` ranges over the multiplicity of `r`. In the cases where the roots are complex, solutions of the form `C_1 x^a \sin(b \log(x)) + C_2 x^a \cos(b \log(x))` are returned, based on expansions with Euler's formula. The general solution is the sum of the terms found. If SymPy cannot find exact roots to the characteristic equation, a :py:class:`~sympy.polys.rootoftools.CRootOf` instance will be returned instead. >>> from sympy import Function, dsolve, Eq >>> from sympy.abc import x >>> f = Function('f') >>> dsolve(4x*2f(x).diff(x, 2) + f(x), f(x), ... hint='nth_linear_euler_eq_homogeneous') ... # doctest: +NORMALIZE_WHITESPACE Eq(f(x), sqrt(x)(C1 + C2log(x))) Note that because this method does not involve integration, there is no ``nth_linear_euler_eq_homogeneous_Integral`` hint. The following is for internal use: - ``returns = 'sol'`` returns the solution to the ODE. - ``returns = 'list'`` returns a list of linearly independent solutions, corresponding to the fundamental solution set, for use with non homogeneous solution methods like variation of parameters and undetermined coefficients. Note that, though the solutions should be linearly independent, this function does not explicitly check that. You can do ``assert simplify(wronskian(sollist)) != 0`` to check for linear independence. Also, ``assert len(sollist) == order`` will need to pass. - ``returns = 'both'``, return a dictionary ``{'sol': <solution to ODE>, 'list': <list of linearly independent solutions>}``. Examples ======== >>> from sympy import Function, dsolve, pprint >>> from sympy.abc import x >>> f = Function('f') >>> eq = f(x).diff(x, 2)x2 - 4f(x).diff(x)x + 6f(x) >>> pprint(dsolve(eq, f(x), ... hint='nth_linear_euler_eq_homogeneous')) 2 f(x) = x (C1 + C2x) References ========== - https://en.wikipedia.org/wiki/Cauchy%E2%80%93Euler_equation - C. Bender & S. Orszag, "Advanced Mathematical Methods for Scientists and Engineers", Springer 1999, pp. 12 # indirect doctest """ global collectterms collectterms = [] x = func.args[0] f = func.func r = match # First, set up characteristic equation. chareq, symbol = S.Zero, Dummy('x') for i in r.keys(): if not isinstance(i, str) and i >= 0: chareq += (r[i]diff(xsymbol, x, i)x*-symbol).expand() chareq = Poly(chareq, symbol) chareqroots = [rootof(chareq, k) for k in range(chareq.degree())] # A generator of constants constants = list(get_numbered_constants(eq, num=chareq.degree()2)) constants.reverse() # Create a dict root: multiplicity or charroots charroots = defaultdict(int) for root in chareqroots: charroots[root] += 1 gsol = S(0) # We need keep track of terms so we can run collect() at the end. # This is necessary for constantsimp to work properly. ln = log for root, multiplicity in charroots.items(): for i in range(multiplicity): if isinstance(root, RootOf): gsol += (x*root) constants.pop() if multiplicity != 1: raise ValueError("Value should be 1") collectterms = [(0, root, 0)] + collectterms elif root.is_real: gsol += ln(x)*i(x*root) constants.pop() collectterms = [(i, root, 0)] + collectterms else: reroot = re(root) imroot = im(root) gsol += ln(x)*i (x*reroot) ( constants.pop() * sin(abs(imroot)ln(x)) + constants.pop() cos(imrootln(x))) # Preserve ordering (multiplicity, real part, imaginary part) # It will be assumed implicitly when constructing # fundamental solution sets. collectterms = [(i, reroot, imroot)] + collectterms if returns == 'sol': return Eq(f(x), gsol) elif returns in ('list' 'both'): # HOW TO TEST THIS CODE? (dsolve does not pass 'returns' through) # Create a list of (hopefully) linearly independent solutions gensols = [] # Keep track of when to use sin or cos for nonzero imroot for i, reroot, imroot in collectterms: if imroot == 0: gensols.append(ln(x)ixreroot) else: sin_form = ln(x)ixrerootsin(abs(imroot)ln(x)) if sin_form in gensols: cos_form = ln(x)ix*rerootcos(imrootln(x)) gensols.append(cos_form) else: gensols.append(sin_form) if returns == 'list': return gensols else: return {'sol': Eq(f(x), gsol), 'list': gensols} else: raise ValueError('Unknown value for key "returns".') def ode_nth_linear_euler_eq_nonhomogeneous_undetermined_coefficients(eq, func, order, match, returns='sol'): r""" Solves an `n`\th order linear non homogeneous Cauchy-Euler equidimensional ordinary differential equation using undetermined coefficients. This is an equation with form `g(x) = a_0 f(x) + a_1 x f'(x) + a_2 x^2 f''(x) \cdots`. These equations can be solved in a general manner, by substituting solutions of the form `x = exp(t)`, and deriving a characteristic equation of form `g(exp(t)) = b_0 f(t) + b_1 f'(t) + b_2 f''(t) \cdots` which can be then solved by nth_linear_constant_coeff_undetermined_coefficients if g(exp(t)) has finite number of linearly independent derivatives. Functions that fit this requirement are finite sums functions of the form `a x^i e^{b x} \sin(c x + d)` or `a x^i e^{b x} \cos(c x + d)`, where `i` is a non-negative integer and `a`, `b`, `c`, and `d` are constants. For example any polynomial in `x`, functions like `x^2 e^{2 x}`, `x \sin(x)`, and `e^x \cos(x)` can all be used. Products of `\sin`'s and `\cos`'s have a finite number of derivatives, because they can be expanded into `\sin(a x)` and `\cos(b x)` terms. However, SymPy currently cannot do that expansion, so you will need to manually rewrite the expression in terms of the above to use this method. So, for example, you will need to manually convert `\sin^2(x)` into `(1 + \cos(2 x))/2` to properly apply the method of undetermined coefficients on it. After replacement of x by exp(t), this method works by creating a trial function from the expression and all of its linear independent derivatives and substituting them into the original ODE. The coefficients for each term will be a system of linear equations, which are be solved for and substituted, giving the solution. If any of the trial functions are linearly dependent on the solution to the homogeneous equation, they are multiplied by sufficient `x` to make them linearly independent. Examples ======== >>> from sympy import dsolve, Function, Derivative, log >>> from sympy.abc import x >>> f = Function('f') >>> eq = x2Derivative(f(x), x, x) - 2xDerivative(f(x), x) + 2f(x) - log(x) >>> dsolve(eq, f(x), ... hint='nth_linear_euler_eq_nonhomogeneous_undetermined_coefficients').expand() Eq(f(x), C1x + C2x2 + log(x)/2 + 3/4) """ x = func.args[0] f = func.func r = match chareq, eq, symbol = S.Zero, S.Zero, Dummy('x') for i in r.keys(): if not isinstance(i, str) and i >= 0: chareq += (r[i]diff(x*symbol, x, i)x-symbol).expand() for i in range(1,degree(Poly(chareq, symbol))+1): eq += chareq.coeff(symboli)diff(f(x), x, i) if chareq.as_coeff_add(symbol)[0]: eq += chareq.as_coeff_add(symbol)[0]f(x) e, re = posify(r[-1].subs(x, exp(x))) eq += e.subs(re) match = _nth_linear_match(eq, f(x), ode_order(eq, f(x))) match['trialset'] = r['trialset'] return ode_nth_linear_constant_coeff_undetermined_coefficients(eq, func, order, match).subs(x, log(x)).subs(f(log(x)), f(x)).expand() def ode_nth_linear_euler_eq_nonhomogeneous_variation_of_parameters(eq, func, order, match, returns='sol'): r""" Solves an `n`\th order linear non homogeneous Cauchy-Euler equidimensional ordinary differential equation using variation of parameters. This is an equation with form `g(x) = a_0 f(x) + a_1 x f'(x) + a_2 x^2 f''(x) \cdots`. This method works by assuming that the particular solution takes the form .. math:: \sum_{x=1}^{n} c_i(x) y_i(x) {a_n} {x^n} \text{,} where `y_i` is the `i`\th solution to the homogeneous equation. The solution is then solved using Wronskian's and Cramer's Rule. The particular solution is given by multiplying eq given below with `a_n x^{n}` .. math:: \sum_{x=1}^n \left( \int \frac{W_i(x)}{W(x)} \,dx \right) y_i(x) \text{,} where `W(x)` is the Wronskian of the fundamental system (the system of `n` linearly independent solutions to the homogeneous equation), and `W_i(x)` is the Wronskian of the fundamental system with the `i`\th column replaced with `[0, 0, \cdots, 0, \frac{x^{- n}}{a_n} g{\left(x \right)}]`. This method is general enough to solve any `n`\th order inhomogeneous linear differential equation, but sometimes SymPy cannot simplify the Wronskian well enough to integrate it. If this method hangs, try using the ``nth_linear_constant_coeff_variation_of_parameters_Integral`` hint and simplifying the integrals manually. Also, prefer using ``nth_linear_constant_coeff_undetermined_coefficients`` when it applies, because it doesn't use integration, making it faster and more reliable. Warning, using simplify=False with 'nth_linear_constant_coeff_variation_of_parameters' in :py:meth:`~sympy.solvers.ode.dsolve` may cause it to hang, because it will not attempt to simplify the Wronskian before integrating. It is recommended that you only use simplify=False with 'nth_linear_constant_coeff_variation_of_parameters_Integral' for this method, especially if the solution to the homogeneous equation has trigonometric functions in it. Examples ======== >>> from sympy import Function, dsolve, Derivative >>> from sympy.abc import x >>> f = Function('f') >>> eq = x*2Derivative(f(x), x, x) - 2xDerivative(f(x), x) + 2f(x) - x4 >>> dsolve(eq, f(x), ... hint='nth_linear_euler_eq_nonhomogeneous_variation_of_parameters').expand() Eq(f(x), C1x + C2x2 + x4/6) """ x = func.args[0] f = func.func r = match gensol = ode_nth_linear_euler_eq_homogeneous(eq, func, order, match, returns='both') match.update(gensol) r[-1] = r[-1]/r[ode_order(eq, f(x))] sol = _solve_variation_of_parameters(eq, func, order, match) return Eq(f(x), r['sol'].rhs + (sol.rhs - r['sol'].rhs)r[ode_order(eq, f(x))]) def ode_almost_linear(eq, func, order, match): r""" Solves an almost-linear differential equation. The general form of an almost linear differential equation is .. math:: f(x) g(y) y + k(x) l(y) + m(x) = 0 \text{where} l'(y) = g(y)\text{.} This can be solved by substituting `l(y) = u(y)`. Making the given substitution reduces it to a linear differential equation of the form `u' + P(x) u + Q(x) = 0`. The general solution is >>> from sympy import Function, dsolve, Eq, pprint >>> from sympy.abc import x, y, n >>> f, g, k, l = map(Function, ['f', 'g', 'k', 'l']) >>> genform = Eq(f(x)(l(y).diff(y)) + k(x)l(y) + g(x)) >>> pprint(genform) d f(x)--(l(y)) + g(x) + k(x)l(y) = 0 dy >>> pprint(dsolve(genform, hint = 'almost_linear')) / // yk(x) \\ \| \|\| ------ \|\| \| \|\| f(x) \|\| -yk(x) \| \|\|-g(x)e \|\| -------- \| \|\|-------------- for k(x) != 0\|\| f(x) l(y) = \|C1 + \|< k(x) \|\|e \| \|\| \|\| \| \|\| -yg(x) \|\| \| \|\| -------- otherwise \|\| \| \|\| f(x) \|\| \ \\ // See Also ======== :meth:`sympy.solvers.ode.ode_1st_linear` Examples ======== >>> from sympy import Function, Derivative, pprint >>> from sympy.solvers.ode import dsolve, classify_ode >>> from sympy.abc import x >>> f = Function('f') >>> d = f(x).diff(x) >>> eq = xd + xf(x) + 1 >>> dsolve(eq, f(x), hint='almost_linear') Eq(f(x), (C1 - Ei(x))exp(-x)) >>> pprint(dsolve(eq, f(x), hint='almost_linear')) -x f(x) = (C1 - Ei(x))e References ========== - Joel Moses, "Symbolic Integration - The Stormy Decade", Communications of the ACM, Volume 14, Number 8, August 1971, pp. 558 """ # Since ode_1st_linear has already been implemented, and the # coefficients have been modified to the required form in # classify_ode, just passing eq, func, order and match to # ode_1st_linear will give the required output. return ode_1st_linear(eq, func, order, match) def _linear_coeff_match(expr, func): r""" Helper function to match hint ``linear_coefficients``. Matches the expression to the form `(a_1 x + b_1 f(x) + c_1)/(a_2 x + b_2 f(x) + c_2)` where the following conditions hold: 1. `a_1`, `b_1`, `c_1`, `a_2`, `b_2`, `c_2` are Rationals; 2. `c_1` or `c_2` are not equal to zero; 3. `a_2 b_1 - a_1 b_2` is not equal to zero. Return ``xarg``, ``yarg`` where 1. ``xarg`` = `(b_2 c_1 - b_1 c_2)/(a_2 b_1 - a_1 b_2)` 2. ``yarg`` = `(a_1 c_2 - a_2 c_1)/(a_2 b_1 - a_1 b_2)` Examples ======== >>> from sympy import Function >>> from sympy.abc import x >>> from sympy.solvers.ode import _linear_coeff_match >>> from sympy.functions.elementary.trigonometric import sin >>> f = Function('f') >>> _linear_coeff_match(( ... (-25f(x) - 8x + 62)/(4f(x) + 11x - 11)), f(x)) (1/9, 22/9) >>> _linear_coeff_match( ... sin((-5f(x) - 8x + 6)/(4f(x) + x - 1)), f(x)) (19/27, 2/27) >>> _linear_coeff_match(sin(f(x)/x), f(x)) """ f = func.func x = func.args[0] def abc(eq): r''' Internal function of _linear_coeff_match that returns Rationals a, b, c if eq is ax + bf(x) + c, else None. ''' eq = _mexpand(eq) c = eq.as_independent(x, f(x), as_Add=True)[0] if not c.is_Rational: return a = eq.coeff(x) if not a.is_Rational: return b = eq.coeff(f(x)) if not b.is_Rational: return if eq == ax + bf(x) + c: return a, b, c def match(arg): r''' Internal function of _linear_coeff_match that returns Rationals a1, b1, c1, a2, b2, c2 and a2b1 - a1b2 of the expression (a1x + b1f(x) + c1)/(a2x + b2f(x) + c2) if one of c1 or c2 and a2b1 - a1b2 is non-zero, else None. ''' n, d = arg.together().as_numer_denom() m = abc(n) if m is not None: a1, b1, c1 = m m = abc(d) if m is not None: a2, b2, c2 = m d = a2b1 - a1b2 if (c1 or c2) and d: return a1, b1, c1, a2, b2, c2, d m = [fi.args[0] for fi in expr.atoms(Function) if fi.func != f and len(fi.args) == 1 and not fi.args[0].is_Function] or {expr} m1 = match(m.pop()) if m1 and all(match(mi) == m1 for mi in m): a1, b1, c1, a2, b2, c2, denom = m1 return (b2c1 - b1c2)/denom, (a1c2 - a2c1)/denom def ode_linear_coefficients(eq, func, order, match): r""" Solves a differential equation with linear coefficients. The general form of a differential equation with linear coefficients is .. math:: y' + F\left(\!\frac{a_1 x + b_1 y + c_1}{a_2 x + b_2 y + c_2}\!\right) = 0\text{,} where `a_1`, `b_1`, `c_1`, `a_2`, `b_2`, `c_2` are constants and `a_1 b_2 - a_2 b_1 \ne 0`. This can be solved by substituting: .. math:: x = x' + \frac{b_2 c_1 - b_1 c_2}{a_2 b_1 - a_1 b_2} y = y' + \frac{a_1 c_2 - a_2 c_1}{a_2 b_1 - a_1 b_2}\text{.} This substitution reduces the equation to a homogeneous differential equation. See Also ======== :meth:`sympy.solvers.ode.ode_1st_homogeneous_coeff_best` :meth:`sympy.solvers.ode.ode_1st_homogeneous_coeff_subs_indep_div_dep` :meth:`sympy.solvers.ode.ode_1st_homogeneous_coeff_subs_dep_div_indep` Examples ======== >>> from sympy import Function, Derivative, pprint >>> from sympy.solvers.ode import dsolve, classify_ode >>> from sympy.abc import x >>> f = Function('f') >>> df = f(x).diff(x) >>> eq = (x + f(x) + 1)df + (f(x) - 6x + 1) >>> dsolve(eq, hint='linear_coefficients') [Eq(f(x), -x - sqrt(C1 + 7x2) - 1), Eq(f(x), -x + sqrt(C1 + 7x*2) - 1)] >>> pprint(dsolve(eq, hint='linear_coefficients')) ___________ ___________ / 2 / 2 [f(x) = -x - \/ C1 + 7x - 1, f(x) = -x + \/ C1 + 7x - 1] References ========== - Joel Moses, "Symbolic Integration - The Stormy Decade", Communications of the ACM, Volume 14, Number 8, August 1971, pp. 558 """ return ode_1st_homogeneous_coeff_best(eq, func, order, match) def ode_separable_reduced(eq, func, order, match): r""" Solves a differential equation that can be reduced to the separable form. The general form of this equation is .. math:: y' + (y/x) H(x^n y) = 0\text{}. This can be solved by substituting `u(y) = x^n y`. The equation then reduces to the separable form `\frac{u'}{u (\mathrm{power} - H(u))} - \frac{1}{x} = 0`. The general solution is: >>> from sympy import Function, dsolve, Eq, pprint >>> from sympy.abc import x, n >>> f, g = map(Function, ['f', 'g']) >>> genform = f(x).diff(x) + (f(x)/x)g(x*nf(x)) >>> pprint(genform) / n \ d f(x)g\x f(x)/ --(f(x)) + --------------- dx x >>> pprint(dsolve(genform, hint='separable_reduced')) n x f(x) / \| \| 1 \| ------------ dy = C1 + log(x) \| y(n - g(y)) \| / See Also ======== :meth:`sympy.solvers.ode.ode_separable` Examples ======== >>> from sympy import Function, Derivative, pprint >>> from sympy.solvers.ode import dsolve, classify_ode >>> from sympy.abc import x >>> f = Function('f') >>> d = f(x).diff(x) >>> eq = (x - x*2f(x))d - f(x) >>> dsolve(eq, hint='separable_reduced') [Eq(f(x), (-sqrt(C1x*2 + 1) + 1)/x), Eq(f(x), (sqrt(C1x*2 + 1) + 1)/x)] >>> pprint(dsolve(eq, hint='separable_reduced')) ___________ ___________ / 2 / 2 - \/ C1x + 1 + 1 \/ C1x + 1 + 1 [f(x) = --------------------, f(x) = ------------------] x x References ========== - Joel Moses, "Symbolic Integration - The Stormy Decade", Communications of the ACM, Volume 14, Number 8, August 1971, pp. 558 """ # Arguments are passed in a way so that they are coherent with the # ode_separable function x = func.args[0] f = func.func y = Dummy('y') u = match['u'].subs(match['t'], y) ycoeff = 1/(y(match['power'] - u)) m1 = {y: 1, x: -1/x, 'coeff': 1} m2 = {y: ycoeff, x: 1, 'coeff': 1} r = {'m1': m1, 'm2': m2, 'y': y, 'hint': x*match['power']f(x)} return ode_separable(eq, func, order, r) def ode_1st_power_series(eq, func, order, match): r""" The power series solution is a method which gives the Taylor series expansion to the solution of a differential equation. For a first order differential equation `\frac{dy}{dx} = h(x, y)`, a power series solution exists at a point `x = x_{0}` if `h(x, y)` is analytic at `x_{0}`. The solution is given by .. math:: y(x) = y(x_{0}) + \sum_{n = 1}^{\infty} \frac{F_{n}(x_{0},b)(x - x_{0})^n}{n!}, where `y(x_{0}) = b` is the value of y at the initial value of `x_{0}`. To compute the values of the `F_{n}(x_{0},b)` the following algorithm is followed, until the required number of terms are generated. 1. `F_1 = h(x_{0}, b)` 2. `F_{n+1} = \frac{\partial F_{n}}{\partial x} + \frac{\partial F_{n}}{\partial y}F_{1}` Examples ======== >>> from sympy import Function, Derivative, pprint, exp >>> from sympy.solvers.ode import dsolve >>> from sympy.abc import x >>> f = Function('f') >>> eq = exp(x)(f(x).diff(x)) - f(x) >>> pprint(dsolve(eq, hint='1st_power_series')) 3 4 5 C1x C1x C1x / 6\ f(x) = C1 + C1x - ----- + ----- + ----- + O\x / 6 24 60 References ========== - Travis W. Walker, Analytic power series technique for solving first-order differential equations, p.p 17, 18 """ x = func.args[0] y = match['y'] f = func.func h = -match[match['d']]/match[match['e']] point = match.get('f0') value = match.get('f0val') terms = match.get('terms') # First term F = h if not h: return Eq(f(x), value) # Initialization series = value if terms > 1: hc = h.subs({x: point, y: value}) if hc.has(oo) or hc.has(NaN) or hc.has(zoo): # Derivative does not exist, not analytic return Eq(f(x), oo) elif hc: series += hc(x - point) for factcount in range(2, terms): Fnew = F.diff(x) + F.diff(y)h Fnewc = Fnew.subs({x: point, y: value}) # Same logic as above if Fnewc.has(oo) or Fnewc.has(NaN) or Fnewc.has(-oo) or Fnewc.has(zoo): return Eq(f(x), oo) series += Fnewc((x - point)factcount)/factorial(factcount) F = Fnew series += Order(xterms) return Eq(f(x), series) def ode_nth_linear_constant_coeff_homogeneous(eq, func, order, match, returns='sol'): r""" Solves an `n`\th order linear homogeneous differential equation with constant coefficients. This is an equation of the form .. math:: a_n f^{(n)}(x) + a_{n-1} f^{(n-1)}(x) + \cdots + a_1 f'(x) + a_0 f(x) = 0\text{.} These equations can be solved in a general manner, by taking the roots of the characteristic equation `a_n m^n + a_{n-1} m^{n-1} + \cdots + a_1 m + a_0 = 0`. The solution will then be the sum of `C_n x^i e^{r x}` terms, for each where `C_n` is an arbitrary constant, `r` is a root of the characteristic equation and `i` is one of each from 0 to the multiplicity of the root - 1 (for example, a root 3 of multiplicity 2 would create the terms `C_1 e^{3 x} + C_2 x e^{3 x}`). The exponential is usually expanded for complex roots using Euler's equation `e^{I x} = \cos(x) + I \sin(x)`. Complex roots always come in conjugate pairs in polynomials with real coefficients, so the two roots will be represented (after simplifying the constants) as `e^{a x} \left(C_1 \cos(b x) + C_2 \sin(b x)\right)`. If SymPy cannot find exact roots to the characteristic equation, a :py:class:`~sympy.polys.rootoftools.CRootOf` instance will be return instead. >>> from sympy import Function, dsolve, Eq >>> from sympy.abc import x >>> f = Function('f') >>> dsolve(f(x).diff(x, 5) + 10f(x).diff(x) - 2f(x), f(x), ... hint='nth_linear_constant_coeff_homogeneous') ... # doctest: +NORMALIZE_WHITESPACE Eq(f(x), C5exp(xCRootOf(_x*5 + 10_x - 2, 0)) + (C1sin(xim(CRootOf(_x*5 + 10_x - 2, 1))) + C2cos(xim(CRootOf(_x*5 + 10_x - 2, 1))))exp(xre(CRootOf(_x*5 + 10_x - 2, 1))) + (C3sin(xim(CRootOf(_x*5 + 10_x - 2, 3))) + C4cos(xim(CRootOf(_x*5 + 10_x - 2, 3))))exp(xre(CRootOf(_x*5 + 10_x - 2, 3)))) Note that because this method does not involve integration, there is no ``nth_linear_constant_coeff_homogeneous_Integral`` hint. The following is for internal use: - ``returns = 'sol'`` returns the solution to the ODE. - ``returns = 'list'`` returns a list of linearly independent solutions, for use with non homogeneous solution methods like variation of parameters and undetermined coefficients. Note that, though the solutions should be linearly independent, this function does not explicitly check that. You can do ``assert simplify(wronskian(sollist)) != 0`` to check for linear independence. Also, ``assert len(sollist) == order`` will need to pass. - ``returns = 'both'``, return a dictionary ``{'sol': <solution to ODE>, 'list': <list of linearly independent solutions>}``. Examples ======== >>> from sympy import Function, dsolve, pprint >>> from sympy.abc import x >>> f = Function('f') >>> pprint(dsolve(f(x).diff(x, 4) + 2f(x).diff(x, 3) - ... 2f(x).diff(x, 2) - 6f(x).diff(x) + 5f(x), f(x), ... hint='nth_linear_constant_coeff_homogeneous')) x -2x f(x) = (C1 + C2x)e + (C3sin(x) + C4cos(x))e References ========== - https://en.wikipedia.org/wiki/Linear_differential_equation section: Nonhomogeneous_equation_with_constant_coefficients - M. Tenenbaum & H. Pollard, "Ordinary Differential Equations", Dover 1963, pp. 211 # indirect doctest """ x = func.args[0] f = func.func r = match # First, set up characteristic equation. chareq, symbol = S.Zero, Dummy('x') for i in r.keys(): if type(i) == str or i < 0: pass else: chareq += r[i]symboli chareq = Poly(chareq, symbol) # Can't just call roots because it doesn't return rootof for unsolveable # polynomials. chareqroots = roots(chareq, multiple=True) if len(chareqroots) != order: chareqroots = [rootof(chareq, k) for k in range(chareq.degree())] chareq_is_complex = not all([i.is_real for i in chareq.all_coeffs()]) # A generator of constants constants = list(get_numbered_constants(eq, num=chareq.degree()2)) # Create a dict root: multiplicity or charroots charroots = defaultdict(int) for root in chareqroots: charroots[root] += 1 gsol = S(0) # We need to keep track of terms so we can run collect() at the end. # This is necessary for constantsimp to work properly. global collectterms collectterms = [] gensols = [] conjugate_roots = [] # used to prevent double-use of conjugate roots # Loop over roots in theorder provided by roots/rootof... for root in chareqroots: # but don't repoeat multiple roots. if root not in charroots: continue multiplicity = charroots.pop(root) for i in range(multiplicity): if chareq_is_complex: gensols.append(x*iexp(rootx)) collectterms = [(i, root, 0)] + collectterms continue reroot = re(root) imroot = im(root) if imroot.has(atan2) and reroot.has(atan2): # Remove this condition when re and im stop returning # circular atan2 usages. gensols.append(xiexp(rootx)) collectterms = [(i, root, 0)] + collectterms else: if root in conjugate_roots: collectterms = [(i, reroot, imroot)] + collectterms continue if imroot == 0: gensols.append(xiexp(rerootx)) collectterms = [(i, reroot, 0)] + collectterms continue conjugate_roots.append(conjugate(root)) gensols.append(xiexp(rerootx) sin(abs(imroot) * x)) gensols.append(x*iexp(rerootx) cos( imroot * x)) # This ordering is important collectterms = [(i, reroot, imroot)] + collectterms if returns == 'list': return gensols elif returns in ('sol' 'both'): gsol = Add([ij for (i,j) in zip(constants, gensols)]) if returns == 'sol': return Eq(f(x), gsol) else: return {'sol': Eq(f(x), gsol), 'list': gensols} else: raise ValueError('Unknown value for key "returns".') def ode_nth_linear_constant_coeff_undetermined_coefficients(eq, func, order, match): r""" Solves an `n`\th order linear differential equation with constant coefficients using the method of undetermined coefficients. This method works on differential equations of the form .. math:: a_n f^{(n)}(x) + a_{n-1} f^{(n-1)}(x) + \cdots + a_1 f'(x) + a_0 f(x) = P(x)\text{,} where `P(x)` is a function that has a finite number of linearly independent derivatives. Functions that fit this requirement are finite sums functions of the form `a x^i e^{b x} \sin(c x + d)` or `a x^i e^{b x} \cos(c x + d)`, where `i` is a non-negative integer and `a`, `b`, `c`, and `d` are constants. For example any polynomial in `x`, functions like `x^2 e^{2 x}`, `x \sin(x)`, and `e^x \cos(x)` can all be used. Products of `\sin`'s and `\cos`'s have a finite number of derivatives, because they can be expanded into `\sin(a x)` and `\cos(b x)` terms. However, SymPy currently cannot do that expansion, so you will need to manually rewrite the expression in terms of the above to use this method. So, for example, you will need to manually convert `\sin^2(x)` into `(1 + \cos(2 x))/2` to properly apply the method of undetermined coefficients on it. This method works by creating a trial function from the expression and all of its linear independent derivatives and substituting them into the original ODE. The coefficients for each term will be a system of linear equations, which are be solved for and substituted, giving the solution. If any of the trial functions are linearly dependent on the solution to the homogeneous equation, they are multiplied by sufficient `x` to make them linearly independent. Examples ======== >>> from sympy import Function, dsolve, pprint, exp, cos >>> from sympy.abc import x >>> f = Function('f') >>> pprint(dsolve(f(x).diff(x, 2) + 2f(x).diff(x) + f(x) - ... 4exp(-x)x2 + cos(2x), f(x), ... hint='nth_linear_constant_coeff_undetermined_coefficients')) / 4\ \| x \| -x 4sin(2x) 3cos(2x) f(x) = \|C1 + C2x + --\|e - ---------- + ---------- \ 3 / 25 25 References ========== - https://en.wikipedia.org/wiki/Method_of_undetermined_coefficients - M. Tenenbaum & H. Pollard, "Ordinary Differential Equations", Dover 1963, pp. 221 # indirect doctest """ gensol = ode_nth_linear_constant_coeff_homogeneous(eq, func, order, match, returns='both') match.update(gensol) return _solve_undetermined_coefficients(eq, func, order, match) def _solve_undetermined_coefficients(eq, func, order, match): r""" Helper function for the method of undetermined coefficients. See the :py:meth:`~sympy.solvers.ode.ode_nth_linear_constant_coeff_undetermined_coefficients` docstring for more information on this method. The parameter ``match`` should be a dictionary that has the following keys: ``list`` A list of solutions to the homogeneous equation, such as the list returned by ``ode_nth_linear_constant_coeff_homogeneous(returns='list')``. ``sol`` The general solution, such as the solution returned by ``ode_nth_linear_constant_coeff_homogeneous(returns='sol')``. ``trialset`` The set of trial functions as returned by ``_undetermined_coefficients_match()['trialset']``. """ x = func.args[0] f = func.func r = match coeffs = numbered_symbols('a', cls=Dummy) coefflist = [] gensols = r['list'] gsol = r['sol'] trialset = r['trialset'] notneedset = set([]) newtrialset = set([]) global collectterms if len(gensols) != order: raise NotImplementedError("Cannot find " + str(order) + " solutions to the homogeneous equation necessary to apply" + " undetermined coefficients to " + str(eq) + " (number of terms != order)") usedsin = set([]) mult = 0 # The multiplicity of the root getmult = True for i, reroot, imroot in collectterms: if getmult: mult = i + 1 getmult = False if i == 0: getmult = True if imroot: # Alternate between sin and cos if (i, reroot) in usedsin: check = x*iexp(rerootx)cos(imrootx) else: check = xiexp(rerootx)sin(abs(imroot)x) usedsin.add((i, reroot)) else: check = xiexp(rerootx) if check in trialset: # If an element of the trial function is already part of the # homogeneous solution, we need to multiply by sufficient x to # make it linearly independent. We also don't need to bother # checking for the coefficients on those elements, since we # already know it will be 0. while True: if checkx*mult in trialset: mult += 1 else: break trialset.add(checkx*mult) notneedset.add(check) newtrialset = trialset - notneedset trialfunc = 0 for i in newtrialset: c = next(coeffs) coefflist.append(c) trialfunc += ci eqs = sub_func_doit(eq, f(x), trialfunc) coeffsdict = dict(list(zip(trialset, [0](len(trialset) + 1)))) eqs = _mexpand(eqs) for i in Add.make_args(eqs): s = separatevars(i, dict=True, symbols=[x]) coeffsdict[s[x]] += s['coeff'] coeffvals = solve(list(coeffsdict.values()), coefflist) if not coeffvals: raise NotImplementedError( "Could not solve `%s` using the " "method of undetermined coefficients " "(unable to solve for coefficients)." % eq) psol = trialfunc.subs(coeffvals) return Eq(f(x), gsol.rhs + psol) def _undetermined_coefficients_match(expr, x): r""" Returns a trial function match if undetermined coefficients can be applied to ``expr``, and ``None`` otherwise. A trial expression can be found for an expression for use with the method of undetermined coefficients if the expression is an additive/multiplicative combination of constants, polynomials in `x` (the independent variable of expr), `\sin(a x + b)`, `\cos(a x + b)`, and `e^{a x}` terms (in other words, it has a finite number of linearly independent derivatives). Note that you may still need to multiply each term returned here by sufficient `x` to make it linearly independent with the solutions to the homogeneous equation. This is intended for internal use by ``undetermined_coefficients`` hints. SymPy currently has no way to convert `\sin^n(x) \cos^m(y)` into a sum of only `\sin(a x)` and `\cos(b x)` terms, so these are not implemented. So, for example, you will need to manually convert `\sin^2(x)` into `[1 + \cos(2 x)]/2` to properly apply the method of undetermined coefficients on it. Examples ======== >>> from sympy import log, exp >>> from sympy.solvers.ode import _undetermined_coefficients_match >>> from sympy.abc import x >>> _undetermined_coefficients_match(9xexp(x) + exp(-x), x) {'test': True, 'trialset': {xexp(x), exp(-x), exp(x)}} >>> _undetermined_coefficients_match(log(x), x) {'test': False} """ a = Wild('a', exclude=[x]) b = Wild('b', exclude=[x]) expr = powsimp(expr, combine='exp') # exp(x)exp(2x + 1) => exp(3x + 1) retdict = {} def _test_term(expr, x): r""" Test if ``expr`` fits the proper form for undetermined coefficients. """ if not expr.has(x): return True elif expr.is_Add: return all(_test_term(i, x) for i in expr.args) elif expr.is_Mul: if expr.has(sin, cos): foundtrig = False # Make sure that there is only one trig function in the args. # See the docstring. for i in expr.args: if i.has(sin, cos): if foundtrig: return False else: foundtrig = True return all(_test_term(i, x) for i in expr.args) elif expr.is_Function: if expr.func in (sin, cos, exp): if expr.args[0].match(ax + b): return True else: return False else: return False elif expr.is_Pow and expr.base.is_Symbol and expr.exp.is_Integer and \ expr.exp >= 0: return True elif expr.is_Pow and expr.base.is_number: if expr.exp.match(ax + b): return True else: return False elif expr.is_Symbol or expr.is_number: return True else: return False def _get_trial_set(expr, x, exprs=set([])): r""" Returns a set of trial terms for undetermined coefficients. The idea behind undetermined coefficients is that the terms expression repeat themselves after a finite number of derivatives, except for the coefficients (they are linearly dependent). So if we collect these, we should have the terms of our trial function. """ def _remove_coefficient(expr, x): r""" Returns the expression without a coefficient. Similar to expr.as_independent(x)[1], except it only works multiplicatively. """ term = S.One if expr.is_Mul: for i in expr.args: if i.has(x): term = i elif expr.has(x): term = expr return term expr = expand_mul(expr) if expr.is_Add: for term in expr.args: if _remove_coefficient(term, x) in exprs: pass else: exprs.add(_remove_coefficient(term, x)) exprs = exprs.union(_get_trial_set(term, x, exprs)) else: term = _remove_coefficient(expr, x) tmpset = exprs.union({term}) oldset = set([]) while tmpset != oldset: # If you get stuck in this loop, then _test_term is probably # broken oldset = tmpset.copy() expr = expr.diff(x) term = _remove_coefficient(expr, x) if term.is_Add: tmpset = tmpset.union(_get_trial_set(term, x, tmpset)) else: tmpset.add(term) exprs = tmpset return exprs retdict['test'] = _test_term(expr, x) if retdict['test']: # Try to generate a list of trial solutions that will have the # undetermined coefficients. Note that if any of these are not linearly # independent with any of the solutions to the homogeneous equation, # then they will need to be multiplied by sufficient x to make them so. # This function DOES NOT do that (it doesn't even look at the # homogeneous equation). retdict['trialset'] = _get_trial_set(expr, x) return retdict def ode_nth_linear_constant_coeff_variation_of_parameters(eq, func, order, match): r""" Solves an `n`\th order linear differential equation with constant coefficients using the method of variation of parameters. This method works on any differential equations of the form .. math:: f^{(n)}(x) + a_{n-1} f^{(n-1)}(x) + \cdots + a_1 f'(x) + a_0 f(x) = P(x)\text{.} This method works by assuming that the particular solution takes the form .. math:: \sum_{x=1}^{n} c_i(x) y_i(x)\text{,} where `y_i` is the `i`\th solution to the homogeneous equation. The solution is then solved using Wronskian's and Cramer's Rule. The particular solution is given by .. math:: \sum_{x=1}^n \left( \int \frac{W_i(x)}{W(x)} \,dx \right) y_i(x) \text{,} where `W(x)` is the Wronskian of the fundamental system (the system of `n` linearly independent solutions to the homogeneous equation), and `W_i(x)` is the Wronskian of the fundamental system with the `i`\th column replaced with `[0, 0, \cdots, 0, P(x)]`. This method is general enough to solve any `n`\th order inhomogeneous linear differential equation with constant coefficients, but sometimes SymPy cannot simplify the Wronskian well enough to integrate it. If this method hangs, try using the ``nth_linear_constant_coeff_variation_of_parameters_Integral`` hint and simplifying the integrals manually. Also, prefer using ``nth_linear_constant_coeff_undetermined_coefficients`` when it applies, because it doesn't use integration, making it faster and more reliable. Warning, using simplify=False with 'nth_linear_constant_coeff_variation_of_parameters' in :py:meth:`~sympy.solvers.ode.dsolve` may cause it to hang, because it will not attempt to simplify the Wronskian before integrating. It is recommended that you only use simplify=False with 'nth_linear_constant_coeff_variation_of_parameters_Integral' for this method, especially if the solution to the homogeneous equation has trigonometric functions in it. Examples ======== >>> from sympy import Function, dsolve, pprint, exp, log >>> from sympy.abc import x >>> f = Function('f') >>> pprint(dsolve(f(x).diff(x, 3) - 3f(x).diff(x, 2) + ... 3f(x).diff(x) - f(x) - exp(x)log(x), f(x), ... hint='nth_linear_constant_coeff_variation_of_parameters')) / 3 \ \| 2 x (6log(x) - 11)\| x f(x) = \|C1 + C2x + C3x + ------------------\|e \ 36 / References ========== - https://en.wikipedia.org/wiki/Variation_of_parameters - http://planetmath.org/VariationOfParameters - M. Tenenbaum & H. Pollard, "Ordinary Differential Equations", Dover 1963, pp. 233 # indirect doctest """ gensol = ode_nth_linear_constant_coeff_homogeneous(eq, func, order, match, returns='both') match.update(gensol) return _solve_variation_of_parameters(eq, func, order, match) def _solve_variation_of_parameters(eq, func, order, match): r""" Helper function for the method of variation of parameters and nonhomogeneous euler eq. See the :py:meth:`~sympy.solvers.ode.ode_nth_linear_constant_coeff_variation_of_parameters` docstring for more information on this method. The parameter ``match`` should be a dictionary that has the following keys: ``list`` A list of solutions to the homogeneous equation, such as the list returned by ``ode_nth_linear_constant_coeff_homogeneous(returns='list')``. ``sol`` The general solution, such as the solution returned by ``ode_nth_linear_constant_coeff_homogeneous(returns='sol')``. """ x = func.args[0] f = func.func r = match psol = 0 gensols = r['list'] gsol = r['sol'] wr = wronskian(gensols, x) if r.get('simplify', True): wr = simplify(wr) # We need much better simplification for # some ODEs. See issue 4662, for example. # To reduce commonly occurring sin(x)2 + cos(x)2 to 1 wr = trigsimp(wr, deep=True, recursive=True) if not wr: # The wronskian will be 0 iff the solutions are not linearly # independent. raise NotImplementedError("Cannot find " + str(order) + " solutions to the homogeneous equation necessary to apply " + "variation of parameters to " + str(eq) + " (Wronskian == 0)") if len(gensols) != order: raise NotImplementedError("Cannot find " + str(order) + " solutions to the homogeneous equation necessary to apply " + "variation of parameters to " + str(eq) + " (number of terms != order)") negoneterm = (-1)*(order) for i in gensols: psol += negonetermIntegral(wronskian([sol for sol in gensols if sol != i], x)r[-1]/wr, x)i/r[order] negoneterm = -1 if r.get('simplify', True): psol = simplify(psol) psol = trigsimp(psol, deep=True) return Eq(f(x), gsol.rhs + psol) def ode_separable(eq, func, order, match): r""" Solves separable 1st order differential equations. This is any differential equation that can be written as `P(y) \tfrac{dy}{dx} = Q(x)`. The solution can then just be found by rearranging terms and integrating: `\int P(y) \,dy = \int Q(x) \,dx`. This hint uses :py:meth:`sympy.simplify.simplify.separatevars` as its back end, so if a separable equation is not caught by this solver, it is most likely the fault of that function. :py:meth:`~sympy.simplify.simplify.separatevars` is smart enough to do most expansion and factoring necessary to convert a separable equation `F(x, y)` into the proper form `P(x)\cdot{}Q(y)`. The general solution is:: >>> from sympy import Function, dsolve, Eq, pprint >>> from sympy.abc import x >>> a, b, c, d, f = map(Function, ['a', 'b', 'c', 'd', 'f']) >>> genform = Eq(a(x)b(f(x))f(x).diff(x), c(x)d(f(x))) >>> pprint(genform) d a(x)b(f(x))--(f(x)) = c(x)d(f(x)) dx >>> pprint(dsolve(genform, f(x), hint='separable_Integral')) f(x) / / \| \| \| b(y) \| c(x) \| ---- dy = C1 + \| ---- dx \| d(y) \| a(x) \| \| / / Examples ======== >>> from sympy import Function, dsolve, Eq >>> from sympy.abc import x >>> f = Function('f') >>> pprint(dsolve(Eq(f(x)f(x).diff(x) + x, 3xf(x)*2), f(x), ... hint='separable', simplify=False)) / 2 \ 2 log\3f (x) - 1/ x ---------------- = C1 + -- 6 2 References ========== - M. Tenenbaum & H. Pollard, "Ordinary Differential Equations", Dover 1963, pp. 52 # indirect doctest """ x = func.args[0] f = func.func C1 = get_numbered_constants(eq, num=1) r = match # {'m1':m1, 'm2':m2, 'y':y} u = r.get('hint', f(x)) # get u from separable_reduced else get f(x) return Eq(Integral(r['m2']['coeff']r['m2'][r['y']]/r['m1'][r['y']], (r['y'], None, u)), Integral(-r['m1']['coeff']r['m1'][x]/ r['m2'][x], x) + C1) def checkinfsol(eq, infinitesimals, func=None, order=None): r""" This function is used to check if the given infinitesimals are the actual infinitesimals of the given first order differential equation. This method is specific to the Lie Group Solver of ODEs. As of now, it simply checks, by substituting the infinitesimals in the partial differential equation. .. math:: \frac{\partial \eta}{\partial x} + \left(\frac{\partial \eta}{\partial y} - \frac{\partial \xi}{\partial x}\right)h - \frac{\partial \xi}{\partial y}h^{2} - \xi\frac{\partial h}{\partial x} - \eta\frac{\partial h}{\partial y} = 0 where `\eta`, and `\xi` are the infinitesimals and `h(x,y) = \frac{dy}{dx}` The infinitesimals should be given in the form of a list of dicts ``[{xi(x, y): inf, eta(x, y): inf}]``, corresponding to the output of the function infinitesimals. It returns a list of values of the form ``[(True/False, sol)]`` where ``sol`` is the value obtained after substituting the infinitesimals in the PDE. If it is ``True``, then ``sol`` would be 0. """ if isinstance(eq, Equality): eq = eq.lhs - eq.rhs if not func: eq, func = _preprocess(eq) variables = func.args if len(variables) != 1: raise ValueError("ODE's have only one independent variable") else: x = variables[0] if not order: order = ode_order(eq, func) if order != 1: raise NotImplementedError("Lie groups solver has been implemented " "only for first order differential equations") else: df = func.diff(x) a = Wild('a', exclude = [df]) b = Wild('b', exclude = [df]) match = collect(expand(eq), df).match(adf + b) if match: h = -simplify(match[b]/match[a]) else: try: sol = solve(eq, df) except NotImplementedError: raise NotImplementedError("Infinitesimals for the " "first order ODE could not be found") else: h = sol[0] # Find infinitesimals for one solution y = Dummy('y') h = h.subs(func, y) xi = Function('xi')(x, y) eta = Function('eta')(x, y) dxi = Function('xi')(x, func) deta = Function('eta')(x, func) pde = (eta.diff(x) + (eta.diff(y) - xi.diff(x))h - (xi.diff(y))h2 - xi(h.diff(x)) - eta(h.diff(y))) soltup = [] for sol in infinitesimals: tsol = {xi: S(sol[dxi]).subs(func, y), eta: S(sol[deta]).subs(func, y)} sol = simplify(pde.subs(tsol).doit()) if sol: soltup.append((False, sol.subs(y, func))) else: soltup.append((True, 0)) return soltup def ode_lie_group(eq, func, order, match): r""" This hint implements the Lie group method of solving first order differential equations. The aim is to convert the given differential equation from the given coordinate given system into another coordinate system where it becomes invariant under the one-parameter Lie group of translations. The converted ODE is quadrature and can be solved easily. It makes use of the :py:meth:`sympy.solvers.ode.infinitesimals` function which returns the infinitesimals of the transformation. The coordinates `r` and `s` can be found by solving the following Partial Differential Equations. .. math :: \xi\frac{\partial r}{\partial x} + \eta\frac{\partial r}{\partial y} = 0 .. math :: \xi\frac{\partial s}{\partial x} + \eta\frac{\partial s}{\partial y} = 1 The differential equation becomes separable in the new coordinate system .. math :: \frac{ds}{dr} = \frac{\frac{\partial s}{\partial x} + h(x, y)\frac{\partial s}{\partial y}}{ \frac{\partial r}{\partial x} + h(x, y)\frac{\partial r}{\partial y}} After finding the solution by integration, it is then converted back to the original coordinate system by substituting `r` and `s` in terms of `x` and `y` again. Examples ======== >>> from sympy import Function, dsolve, Eq, exp, pprint >>> from sympy.abc import x >>> f = Function('f') >>> pprint(dsolve(f(x).diff(x) + 2xf(x) - xexp(-x*2), f(x), ... hint='lie_group')) / 2\ 2 \| x \| -x f(x) = \|C1 + --\|e \ 2 / References ========== - Solving differential equations by Symmetry Groups, John Starrett, pp. 1 - pp. 14 """ heuristics = lie_heuristics inf = {} f = func.func x = func.args[0] df = func.diff(x) xi = Function("xi") eta = Function("eta") a = Wild('a', exclude = [df]) b = Wild('b', exclude = [df]) xis = match.pop('xi') etas = match.pop('eta') if match: h = -simplify(match[match['d']]/match[match['e']]) y = match['y'] else: try: sol = solve(eq, df) if sol == []: raise NotImplementedError except NotImplementedError: raise NotImplementedError("Unable to solve the differential equation " + str(eq) + " by the lie group method") else: y = Dummy("y") h = sol[0].subs(func, y) if xis is not None and etas is not None: inf = [{xi(x, f(x)): S(xis), eta(x, f(x)): S(etas)}] if not checkinfsol(eq, inf, func=f(x), order=1)[0][0]: raise ValueError("The given infinitesimals xi and eta" " are not the infinitesimals to the given equation") else: heuristics = ["user_defined"] match = {'h': h, 'y': y} # This is done so that if: # a] solve raises a NotImplementedError. # b] any heuristic raises a ValueError # another heuristic can be used. tempsol = [] # Used by solve below for heuristic in heuristics: try: if not inf: inf = infinitesimals(eq, hint=heuristic, func=func, order=1, match=match) except ValueError: continue else: for infsim in inf: xiinf = (infsim[xi(x, func)]).subs(func, y) etainf = (infsim[eta(x, func)]).subs(func, y) # This condition creates recursion while using pdsolve. # Since the first step while solving a PDE of form # a(f(x, y).diff(x)) + b(f(x, y).diff(y)) + c = 0 # is to solve the ODE dy/dx = b/a if simplify(etainf/xiinf) == h: continue rpde = f(x, y).diff(x)xiinf + f(x, y).diff(y)etainf r = pdsolve(rpde, func=f(x, y)).rhs s = pdsolve(rpde - 1, func=f(x, y)).rhs newcoord = [_lie_group_remove(coord) for coord in [r, s]] r = Dummy("r") s = Dummy("s") C1 = Symbol("C1") rcoord = newcoord[0] scoord = newcoord[-1] try: sol = solve([r - rcoord, s - scoord], x, y, dict=True) except NotImplementedError: continue else: sol = sol[0] xsub = sol[x] ysub = sol[y] num = simplify(scoord.diff(x) + scoord.diff(y)h) denom = simplify(rcoord.diff(x) + rcoord.diff(y)h) if num and denom: diffeq = simplify((num/denom).subs([(x, xsub), (y, ysub)])) sep = separatevars(diffeq, symbols=[r, s], dict=True) if sep: # Trying to separate, r and s coordinates deq = integrate((1/sep[s]), s) + C1 - integrate(sep['coeff']sep[r], r) # Substituting and reverting back to original coordinates deq = deq.subs([(r, rcoord), (s, scoord)]) try: sdeq = solve(deq, y) except NotImplementedError: tempsol.append(deq) else: if len(sdeq) == 1: return Eq(f(x), sdeq.pop()) else: return [Eq(f(x), sol) for sol in sdeq] elif denom: # (ds/dr) is zero which means s is constant return Eq(f(x), solve(scoord - C1, y)[0]) elif num: # (dr/ds) is zero which means r is constant return Eq(f(x), solve(rcoord - C1, y)[0]) # If nothing works, return solution as it is, without solving for y if tempsol: if len(tempsol) == 1: return Eq(tempsol.pop().subs(y, f(x)), 0) else: return [Eq(sol.subs(y, f(x)), 0) for sol in tempsol] raise NotImplementedError("The given ODE " + str(eq) + " cannot be solved by" + " the lie group method") def _lie_group_remove(coords): r""" This function is strictly meant for internal use by the Lie group ODE solving method. It replaces arbitrary functions returned by pdsolve with either 0 or 1 or the args of the arbitrary function. The algorithm used is: 1] If coords is an instance of an Undefined Function, then the args are returned 2] If the arbitrary function is present in an Add object, it is replaced by zero. 3] If the arbitrary function is present in an Mul object, it is replaced by one. 4] If coords has no Undefined Function, it is returned as it is. Examples ======== >>> from sympy.solvers.ode import _lie_group_remove >>> from sympy import Function >>> from sympy.abc import x, y >>> F = Function("F") >>> eq = x2y >>> _lie_group_remove(eq) x*2y >>> eq = F(x*2y) >>> _lie_group_remove(eq) x*2y >>> eq = y*2x + F(x*3) >>> _lie_group_remove(eq) xy2 >>> eq = (F(x3) + y)x4 >>> _lie_group_remove(eq) x4y """ if isinstance(coords, AppliedUndef): return coords.args[0] elif coords.is_Add: subfunc = coords.atoms(AppliedUndef) if subfunc: for func in subfunc: coords = coords.subs(func, 0) return coords elif coords.is_Pow: base, expr = coords.as_base_exp() base = _lie_group_remove(base) expr = _lie_group_remove(expr) return base*expr elif coords.is_Mul: mulargs = [] coordargs = coords.args for arg in coordargs: if not isinstance(coords, AppliedUndef): mulargs.append(_lie_group_remove(arg)) return Mul(mulargs) return coords def infinitesimals(eq, func=None, order=None, hint='default', match=None): r""" The infinitesimal functions of an ordinary differential equation, `\xi(x,y)` and `\eta(x,y)`, are the infinitesimals of the Lie group of point transformations for which the differential equation is invariant. So, the ODE `y'=f(x,y)` would admit a Lie group `x^=X(x,y;\varepsilon)=x+\varepsilon\xi(x,y)`, `y^=Y(x,y;\varepsilon)=y+\varepsilon\eta(x,y)` such that `(y^)'=f(x^, y^)`. A change of coordinates, to `r(x,y)` and `s(x,y)`, can be performed so this Lie group becomes the translation group, `r^=r` and `s^=s+\varepsilon`. They are tangents to the coordinate curves of the new system. Consider the transformation `(x, y) \to (X, Y)` such that the differential equation remains invariant. `\xi` and `\eta` are the tangents to the transformed coordinates `X` and `Y`, at `\varepsilon=0`. .. math:: \left(\frac{\partial X(x,y;\varepsilon)}{\partial\varepsilon }\right)\|_{\varepsilon=0} = \xi, \left(\frac{\partial Y(x,y;\varepsilon)}{\partial\varepsilon }\right)\|_{\varepsilon=0} = \eta, The infinitesimals can be found by solving the following PDE: >>> from sympy import Function, diff, Eq, pprint >>> from sympy.abc import x, y >>> xi, eta, h = map(Function, ['xi', 'eta', 'h']) >>> h = h(x, y) # dy/dx = h >>> eta = eta(x, y) >>> xi = xi(x, y) >>> genform = Eq(eta.diff(x) + (eta.diff(y) - xi.diff(x))h ... - (xi.diff(y))h2 - xi(h.diff(x)) - eta(h.diff(y)), 0) >>> pprint(genform) /d d \ d 2 d \|--(eta(x, y)) - --(xi(x, y))\|h(x, y) - eta(x, y)--(h(x, y)) - h (x, y)--(x \dy dx / dy dy <BLANKLINE> d d i(x, y)) - xi(x, y)--(h(x, y)) + --(eta(x, y)) = 0 dx dx Solving the above mentioned PDE is not trivial, and can be solved only by making intelligent assumptions for `\xi` and `\eta` (heuristics). Once an infinitesimal is found, the attempt to find more heuristics stops. This is done to optimise the speed of solving the differential equation. If a list of all the infinitesimals is needed, ``hint`` should be flagged as ``all``, which gives the complete list of infinitesimals. If the infinitesimals for a particular heuristic needs to be found, it can be passed as a flag to ``hint``. Examples ======== >>> from sympy import Function, diff >>> from sympy.solvers.ode import infinitesimals >>> from sympy.abc import x >>> f = Function('f') >>> eq = f(x).diff(x) - x2f(x) >>> infinitesimals(eq) [{eta(x, f(x)): exp(x*3/3), xi(x, f(x)): 0}] References ========== - Solving differential equations by Symmetry Groups, John Starrett, pp. 1 - pp. 14 """ if isinstance(eq, Equality): eq = eq.lhs - eq.rhs if not func: eq, func = _preprocess(eq) variables = func.args if len(variables) != 1: raise ValueError("ODE's have only one independent variable") else: x = variables[0] if not order: order = ode_order(eq, func) if order != 1: raise NotImplementedError("Infinitesimals for only " "first order ODE's have been implemented") else: df = func.diff(x) # Matching differential equation of the form adf + b a = Wild('a', exclude = [df]) b = Wild('b', exclude = [df]) if match: # Used by lie_group hint h = match['h'] y = match['y'] else: match = collect(expand(eq), df).match(adf + b) if match: h = -simplify(match[b]/match[a]) else: try: sol = solve(eq, df) except NotImplementedError: raise NotImplementedError("Infinitesimals for the " "first order ODE could not be found") else: h = sol[0] # Find infinitesimals for one solution y = Dummy("y") h = h.subs(func, y) u = Dummy("u") hx = h.diff(x) hy = h.diff(y) hinv = ((1/h).subs([(x, u), (y, x)])).subs(u, y) # Inverse ODE match = {'h': h, 'func': func, 'hx': hx, 'hy': hy, 'y': y, 'hinv': hinv} if hint == 'all': xieta = [] for heuristic in lie_heuristics: function = globals()['lie_heuristic_' + heuristic] inflist = function(match, comp=True) if inflist: xieta.extend([inf for inf in inflist if inf not in xieta]) if xieta: return xieta else: raise NotImplementedError("Infinitesimals could not be found for " "the given ODE") elif hint == 'default': for heuristic in lie_heuristics: function = globals()['lie_heuristic_' + heuristic] xieta = function(match, comp=False) if xieta: return xieta raise NotImplementedError("Infinitesimals could not be found for" " the given ODE") elif hint not in lie_heuristics: raise ValueError("Heuristic not recognized: " + hint) else: function = globals()['lie_heuristic_' + hint] xieta = function(match, comp=True) if xieta: return xieta else: raise ValueError("Infinitesimals could not be found using the" " given heuristic") def lie_heuristic_abaco1_simple(match, comp=False): r""" The first heuristic uses the following four sets of assumptions on `\xi` and `\eta` .. math:: \xi = 0, \eta = f(x) .. math:: \xi = 0, \eta = f(y) .. math:: \xi = f(x), \eta = 0 .. math:: \xi = f(y), \eta = 0 The success of this heuristic is determined by algebraic factorisation. For the first assumption `\xi = 0` and `\eta` to be a function of `x`, the PDE .. math:: \frac{\partial \eta}{\partial x} + (\frac{\partial \eta}{\partial y} - \frac{\partial \xi}{\partial x})h - \frac{\partial \xi}{\partial y}h^{2} - \xi\frac{\partial h}{\partial x} - \eta\frac{\partial h}{\partial y} = 0 reduces to `f'(x) - f\frac{\partial h}{\partial y} = 0` If `\frac{\partial h}{\partial y}` is a function of `x`, then this can usually be integrated easily. A similar idea is applied to the other 3 assumptions as well. References ========== - E.S Cheb-Terrab, L.G.S Duarte and L.A,C.P da Mota, Computer Algebra Solving of First Order ODEs Using Symmetry Methods, pp. 8 """ xieta = [] y = match['y'] h = match['h'] func = match['func'] x = func.args[0] hx = match['hx'] hy = match['hy'] xi = Function('xi')(x, func) eta = Function('eta')(x, func) hysym = hy.free_symbols if y not in hysym: try: fx = exp(integrate(hy, x)) except NotImplementedError: pass else: inf = {xi: S(0), eta: fx} if not comp: return [inf] if comp and inf not in xieta: xieta.append(inf) factor = hy/h facsym = factor.free_symbols if x not in facsym: try: fy = exp(integrate(factor, y)) except NotImplementedError: pass else: inf = {xi: S(0), eta: fy.subs(y, func)} if not comp: return [inf] if comp and inf not in xieta: xieta.append(inf) factor = -hx/h facsym = factor.free_symbols if y not in facsym: try: fx = exp(integrate(factor, x)) except NotImplementedError: pass else: inf = {xi: fx, eta: S(0)} if not comp: return [inf] if comp and inf not in xieta: xieta.append(inf) factor = -hx/(h2) facsym = factor.free_symbols if x not in facsym: try: fy = exp(integrate(factor, y)) except NotImplementedError: pass else: inf = {xi: fy.subs(y, func), eta: S(0)} if not comp: return [inf] if comp and inf not in xieta: xieta.append(inf) if xieta: return xieta def lie_heuristic_abaco1_product(match, comp=False): r""" The second heuristic uses the following two assumptions on `\xi` and `\eta` .. math:: \eta = 0, \xi = f(x)g(y) .. math:: \eta = f(x)g(y), \xi = 0 The first assumption of this heuristic holds good if `\frac{1}{h^{2}}\frac{\partial^2}{\partial x \partial y}\log(h)` is separable in `x` and `y`, then the separated factors containing `x` is `f(x)`, and `g(y)` is obtained by .. math:: e^{\int f\frac{\partial}{\partial x}\left(\frac{1}{fh}\right)\,dy} provided `f\frac{\partial}{\partial x}\left(\frac{1}{fh}\right)` is a function of `y` only. The second assumption holds good if `\frac{dy}{dx} = h(x, y)` is rewritten as `\frac{dy}{dx} = \frac{1}{h(y, x)}` and the same properties of the first assumption satisfies. After obtaining `f(x)` and `g(y)`, the coordinates are again interchanged, to get `\eta` as `f(x)g(y)` References ========== - E.S. Cheb-Terrab, A.D. Roche, Symmetries and First Order ODE Patterns, pp. 7 - pp. 8 """ xieta = [] y = match['y'] h = match['h'] hinv = match['hinv'] func = match['func'] x = func.args[0] xi = Function('xi')(x, func) eta = Function('eta')(x, func) inf = separatevars(((log(h).diff(y)).diff(x))/h*2, dict=True, symbols=[x, y]) if inf and inf['coeff']: fx = inf[x] gy = simplify(fx((1/(fxh)).diff(x))) gysyms = gy.free_symbols if x not in gysyms: gy = exp(integrate(gy, y)) inf = {eta: S(0), xi: (fxgy).subs(y, func)} if not comp: return [inf] if comp and inf not in xieta: xieta.append(inf) u1 = Dummy("u1") inf = separatevars(((log(hinv).diff(y)).diff(x))/hinv*2, dict=True, symbols=[x, y]) if inf and inf['coeff']: fx = inf[x] gy = simplify(fx((1/(fxhinv)).diff(x))) gysyms = gy.free_symbols if x not in gysyms: gy = exp(integrate(gy, y)) etaval = fxgy etaval = (etaval.subs([(x, u1), (y, x)])).subs(u1, y) inf = {eta: etaval.subs(y, func), xi: S(0)} if not comp: return [inf] if comp and inf not in xieta: xieta.append(inf) if xieta: return xieta def lie_heuristic_bivariate(match, comp=False): r""" The third heuristic assumes the infinitesimals `\xi` and `\eta` to be bi-variate polynomials in `x` and `y`. The assumption made here for the logic below is that `h` is a rational function in `x` and `y` though that may not be necessary for the infinitesimals to be bivariate polynomials. The coefficients of the infinitesimals are found out by substituting them in the PDE and grouping similar terms that are polynomials and since they form a linear system, solve and check for non trivial solutions. The degree of the assumed bivariates are increased till a certain maximum value. References ========== - Lie Groups and Differential Equations pp. 327 - pp. 329 """ h = match['h'] hx = match['hx'] hy = match['hy'] func = match['func'] x = func.args[0] y = match['y'] xi = Function('xi')(x, func) eta = Function('eta')(x, func) if h.is_rational_function(): # The maximum degree that the infinitesimals can take is # calculated by this technique. etax, etay, etad, xix, xiy, xid = symbols("etax etay etad xix xiy xid") ipde = etax + (etay - xix)h - xiyh*2 - xidhx - etadhy num, denom = cancel(ipde).as_numer_denom() deg = Poly(num, x, y).total_degree() deta = Function('deta')(x, y) dxi = Function('dxi')(x, y) ipde = (deta.diff(x) + (deta.diff(y) - dxi.diff(x))h - (dxi.diff(y))h2 - dxihx - detahy) xieq = Symbol("xi0") etaeq = Symbol("eta0") for i in range(deg + 1): if i: xieq += Add([ Symbol("xi_" + str(power) + "_" + str(i - power))xpowery*(i - power) for power in range(i + 1)]) etaeq += Add([ Symbol("eta_" + str(power) + "_" + str(i - power))xpowery*(i - power) for power in range(i + 1)]) pden, denom = (ipde.subs({dxi: xieq, deta: etaeq}).doit()).as_numer_denom() pden = expand(pden) # If the individual terms are monomials, the coefficients # are grouped if pden.is_polynomial(x, y) and pden.is_Add: polyy = Poly(pden, x, y).as_dict() if polyy: symset = xieq.free_symbols.union(etaeq.free_symbols) - {x, y} soldict = solve(polyy.values(), symset) if isinstance(soldict, list): soldict = soldict[0] if any(x for x in soldict.values()): xired = xieq.subs(soldict) etared = etaeq.subs(soldict) # Scaling is done by substituting one for the parameters # This can be any number except zero. dict_ = dict((sym, 1) for sym in symset) inf = {eta: etared.subs(dict_).subs(y, func), xi: xired.subs(dict_).subs(y, func)} return [inf] def lie_heuristic_chi(match, comp=False): r""" The aim of the fourth heuristic is to find the function `\chi(x, y)` that satisfies the PDE `\frac{d\chi}{dx} + h\frac{d\chi}{dx} - \frac{\partial h}{\partial y}\chi = 0`. This assumes `\chi` to be a bivariate polynomial in `x` and `y`. By intuition, `h` should be a rational function in `x` and `y`. The method used here is to substitute a general binomial for `\chi` up to a certain maximum degree is reached. The coefficients of the polynomials, are calculated by by collecting terms of the same order in `x` and `y`. After finding `\chi`, the next step is to use `\eta = \xih + \chi`, to determine `\xi` and `\eta`. This can be done by dividing `\chi` by `h` which would give `-\xi` as the quotient and `\eta` as the remainder. References ========== - E.S Cheb-Terrab, L.G.S Duarte and L.A,C.P da Mota, Computer Algebra Solving of First Order ODEs Using Symmetry Methods, pp. 8 """ h = match['h'] hx = match['hx'] hy = match['hy'] func = match['func'] x = func.args[0] y = match['y'] xi = Function('xi')(x, func) eta = Function('eta')(x, func) if h.is_rational_function(): schi, schix, schiy = symbols("schi, schix, schiy") cpde = schix + hschiy - hyschi num, denom = cancel(cpde).as_numer_denom() deg = Poly(num, x, y).total_degree() chi = Function('chi')(x, y) chix = chi.diff(x) chiy = chi.diff(y) cpde = chix + hchiy - hychi chieq = Symbol("chi") for i in range(1, deg + 1): chieq += Add([ Symbol("chi_" + str(power) + "_" + str(i - power))xpowery*(i - power) for power in range(i + 1)]) cnum, cden = cancel(cpde.subs({chi : chieq}).doit()).as_numer_denom() cnum = expand(cnum) if cnum.is_polynomial(x, y) and cnum.is_Add: cpoly = Poly(cnum, x, y).as_dict() if cpoly: solsyms = chieq.free_symbols - {x, y} soldict = solve(cpoly.values(), solsyms) if isinstance(soldict, list): soldict = soldict[0] if any(x for x in soldict.values()): chieq = chieq.subs(soldict) dict_ = dict((sym, 1) for sym in solsyms) chieq = chieq.subs(dict_) # After finding chi, the main aim is to find out # eta, xi by the equation eta = xih + chi # One method to set xi, would be rearranging it to # (eta/h) - xi = (chi/h). This would mean dividing # chi by h would give -xi as the quotient and eta # as the remainder. Thanks to Sean Vig for suggesting # this method. xic, etac = div(chieq, h) inf = {eta: etac.subs(y, func), xi: -xic.subs(y, func)} return [inf] def lie_heuristic_function_sum(match, comp=False): r""" This heuristic uses the following two assumptions on `\xi` and `\eta` .. math:: \eta = 0, \xi = f(x) + g(y) .. math:: \eta = f(x) + g(y), \xi = 0 The first assumption of this heuristic holds good if .. math:: \frac{\partial}{\partial y}[(h\frac{\partial^{2}}{ \partial x^{2}}(h^{-1}))^{-1}] is separable in `x` and `y`, 1. The separated factors containing `y` is `\frac{\partial g}{\partial y}`. From this `g(y)` can be determined. 2. The separated factors containing `x` is `f''(x)`. 3. `h\frac{\partial^{2}}{\partial x^{2}}(h^{-1})` equals `\frac{f''(x)}{f(x) + g(y)}`. From this `f(x)` can be determined. The second assumption holds good if `\frac{dy}{dx} = h(x, y)` is rewritten as `\frac{dy}{dx} = \frac{1}{h(y, x)}` and the same properties of the first assumption satisfies. After obtaining `f(x)` and `g(y)`, the coordinates are again interchanged, to get `\eta` as `f(x) + g(y)`. For both assumptions, the constant factors are separated among `g(y)` and `f''(x)`, such that `f''(x)` obtained from 3] is the same as that obtained from 2]. If not possible, then this heuristic fails. References ========== - E.S. Cheb-Terrab, A.D. Roche, Symmetries and First Order ODE Patterns, pp. 7 - pp. 8 """ xieta = [] h = match['h'] hx = match['hx'] hy = match['hy'] func = match['func'] hinv = match['hinv'] x = func.args[0] y = match['y'] xi = Function('xi')(x, func) eta = Function('eta')(x, func) for odefac in [h, hinv]: factor = odefac((1/odefac).diff(x, 2)) sep = separatevars((1/factor).diff(y), dict=True, symbols=[x, y]) if sep and sep['coeff'] and sep[x].has(x) and sep[y].has(y): k = Dummy("k") try: gy = kintegrate(sep[y], y) except NotImplementedError: pass else: fdd = 1/(ksep[x]sep['coeff']) fx = simplify(fdd/factor - gy) check = simplify(fx.diff(x, 2) - fdd) if fx: if not check: fx = fx.subs(k, 1) gy = (gy/k) else: sol = solve(check, k) if sol: sol = sol[0] fx = fx.subs(k, sol) gy = (gy/k)sol else: continue if odefac == hinv: # Inverse ODE fx = fx.subs(x, y) gy = gy.subs(y, x) etaval = factor_terms(fx + gy) if etaval.is_Mul: etaval = Mul([arg for arg in etaval.args if arg.has(x, y)]) if odefac == hinv: # Inverse ODE inf = {eta: etaval.subs(y, func), xi : S(0)} else: inf = {xi: etaval.subs(y, func), eta : S(0)} if not comp: return [inf] else: xieta.append(inf) if xieta: return xieta def lie_heuristic_abaco2_similar(match, comp=False): r""" This heuristic uses the following two assumptions on `\xi` and `\eta` .. math:: \eta = g(x), \xi = f(x) .. math:: \eta = f(y), \xi = g(y) For the first assumption, 1. First `\frac{\frac{\partial h}{\partial y}}{\frac{\partial^{2} h}{ \partial yy}}` is calculated. Let us say this value is A 2. If this is constant, then `h` is matched to the form `A(x) + B(x)e^{ \frac{y}{C}}` then, `\frac{e^{\int \frac{A(x)}{C} \,dx}}{B(x)}` gives `f(x)` and `A(x)f(x)` gives `g(x)` 3. Otherwise `\frac{\frac{\partial A}{\partial X}}{\frac{\partial A}{ \partial Y}} = \gamma` is calculated. If a] `\gamma` is a function of `x` alone b] `\frac{\gamma\frac{\partial h}{\partial y} - \gamma'(x) - \frac{ \partial h}{\partial x}}{h + \gamma} = G` is a function of `x` alone. then, `e^{\int G \,dx}` gives `f(x)` and `-\gammaf(x)` gives `g(x)` The second assumption holds good if `\frac{dy}{dx} = h(x, y)` is rewritten as `\frac{dy}{dx} = \frac{1}{h(y, x)}` and the same properties of the first assumption satisfies. After obtaining `f(x)` and `g(x)`, the coordinates are again interchanged, to get `\xi` as `f(x^)` and `\eta` as `g(y^)` References ========== - E.S. Cheb-Terrab, A.D. Roche, Symmetries and First Order ODE Patterns, pp. 10 - pp. 12 """ xieta = [] h = match['h'] hx = match['hx'] hy = match['hy'] func = match['func'] hinv = match['hinv'] x = func.args[0] y = match['y'] xi = Function('xi')(x, func) eta = Function('eta')(x, func) factor = cancel(h.diff(y)/h.diff(y, 2)) factorx = factor.diff(x) factory = factor.diff(y) if not factor.has(x) and not factor.has(y): A = Wild('A', exclude=[y]) B = Wild('B', exclude=[y]) C = Wild('C', exclude=[x, y]) match = h.match(A + Bexp(y/C)) try: tau = exp(-integrate(match[A]/match[C]), x)/match[B] except NotImplementedError: pass else: gx = match[A]tau return [{xi: tau, eta: gx}] else: gamma = cancel(factorx/factory) if not gamma.has(y): tauint = cancel((gammahy - gamma.diff(x) - hx)/(h + gamma)) if not tauint.has(y): try: tau = exp(integrate(tauint, x)) except NotImplementedError: pass else: gx = -taugamma return [{xi: tau, eta: gx}] factor = cancel(hinv.diff(y)/hinv.diff(y, 2)) factorx = factor.diff(x) factory = factor.diff(y) if not factor.has(x) and not factor.has(y): A = Wild('A', exclude=[y]) B = Wild('B', exclude=[y]) C = Wild('C', exclude=[x, y]) match = h.match(A + Bexp(y/C)) try: tau = exp(-integrate(match[A]/match[C]), x)/match[B] except NotImplementedError: pass else: gx = match[A]tau return [{eta: tau.subs(x, func), xi: gx.subs(x, func)}] else: gamma = cancel(factorx/factory) if not gamma.has(y): tauint = cancel((gammahinv.diff(y) - gamma.diff(x) - hinv.diff(x))/( hinv + gamma)) if not tauint.has(y): try: tau = exp(integrate(tauint, x)) except NotImplementedError: pass else: gx = -taugamma return [{eta: tau.subs(x, func), xi: gx.subs(x, func)}] def lie_heuristic_abaco2_unique_unknown(match, comp=False): r""" This heuristic assumes the presence of unknown functions or known functions with non-integer powers. 1. A list of all functions and non-integer powers containing x and y 2. Loop over each element `f` in the list, find `\frac{\frac{\partial f}{\partial x}}{ \frac{\partial f}{\partial x}} = R` If it is separable in `x` and `y`, let `X` be the factors containing `x`. Then a] Check if `\xi = X` and `\eta = -\frac{X}{R}` satisfy the PDE. If yes, then return `\xi` and `\eta` b] Check if `\xi = \frac{-R}{X}` and `\eta = -\frac{1}{X}` satisfy the PDE. If yes, then return `\xi` and `\eta` If not, then check if a] :math:`\xi = -R,\eta = 1` b] :math:`\xi = 1, \eta = -\frac{1}{R}` are solutions. References ========== - E.S. Cheb-Terrab, A.D. Roche, Symmetries and First Order ODE Patterns, pp. 10 - pp. 12 """ xieta = [] h = match['h'] hx = match['hx'] hy = match['hy'] func = match['func'] hinv = match['hinv'] x = func.args[0] y = match['y'] xi = Function('xi')(x, func) eta = Function('eta')(x, func) funclist = [] for atom in h.atoms(Pow): base, exp = atom.as_base_exp() if base.has(x) and base.has(y): if not exp.is_Integer: funclist.append(atom) for function in h.atoms(AppliedUndef): syms = function.free_symbols if x in syms and y in syms: funclist.append(function) for f in funclist: frac = cancel(f.diff(y)/f.diff(x)) sep = separatevars(frac, dict=True, symbols=[x, y]) if sep and sep['coeff']: xitry1 = sep[x] etatry1 = -1/(sep[y]sep['coeff']) pde1 = etatry1.diff(y)h - xitry1.diff(x)h - xitry1hx - etatry1hy if not simplify(pde1): return [{xi: xitry1, eta: etatry1.subs(y, func)}] xitry2 = 1/etatry1 etatry2 = 1/xitry1 pde2 = etatry2.diff(x) - (xitry2.diff(y))h2 - xitry2hx - etatry2hy if not simplify(expand(pde2)): return [{xi: xitry2.subs(y, func), eta: etatry2}] else: etatry = -1/frac pde = etatry.diff(x) + etatry.diff(y)h - hx - etatryhy if not simplify(pde): return [{xi: S(1), eta: etatry.subs(y, func)}] xitry = -frac pde = -xitry.diff(x)h -xitry.diff(y)h2 - xitryhx -hy if not simplify(expand(pde)): return [{xi: xitry.subs(y, func), eta: S(1)}] def lie_heuristic_abaco2_unique_general(match, comp=False): r""" This heuristic finds if infinitesimals of the form `\eta = f(x)`, `\xi = g(y)` without making any assumptions on `h`. The complete sequence of steps is given in the paper mentioned below. References ========== - E.S. Cheb-Terrab, A.D. Roche, Symmetries and First Order ODE Patterns, pp. 10 - pp. 12 """ xieta = [] h = match['h'] hx = match['hx'] hy = match['hy'] func = match['func'] hinv = match['hinv'] x = func.args[0] y = match['y'] xi = Function('xi')(x, func) eta = Function('eta')(x, func) C = S(0) A = hx.diff(y) B = hy.diff(y) + hy2 C = hx.diff(x) - hx2 if not (A and B and C): return Ax = A.diff(x) Ay = A.diff(y) Axy = Ax.diff(y) Axx = Ax.diff(x) Ayy = Ay.diff(y) D = simplify(2Axy + hxAy - Axhy + (hxhy + 2A)A)A - 3AxAy if not D: E1 = simplify(3Ax2 + ((hx2 + 2C)A - 2Axx)A) if E1: E2 = simplify((2Ayy + (2B - hy*2)A)A - 3Ay*2) if not E2: E3 = simplify( E1((28Ax + 4hxA)A*3 - E1(hyA + Ay)) - E1.diff(x)8A4) if not E3: etaval = cancel((4A*3(Ax - hxA) + E1(hyA - Ay))/(S(2)AE1)) if x not in etaval: try: etaval = exp(integrate(etaval, y)) except NotImplementedError: pass else: xival = -4A*3etaval/E1 if y not in xival: return [{xi: xival, eta: etaval.subs(y, func)}] else: E1 = simplify((2Ayy + (2B - hy*2)A)A - 3Ay*2) if E1: E2 = simplify( 4A*3D - D*2 + E1((2Axx - (hx2 + 2C)A)A - 3Ax2)) if not E2: E3 = simplify( -(AD)E1.diff(y) + ((E1.diff(x) - hyD)A + 3AyD + (Ahx - 3Ax)E1)E1) if not E3: etaval = cancel(((Ahx - Ax)E1 - (Ay + Ahy)D)/(S(2)AD)) if x not in etaval: try: etaval = exp(integrate(etaval, y)) except NotImplementedError: pass else: xival = -E1etaval/D if y not in xival: return [{xi: xival, eta: etaval.subs(y, func)}] def lie_heuristic_linear(match, comp=False): r""" This heuristic assumes 1. `\xi = ax + by + c` and 2. `\eta = fx + gy + h` After substituting the following assumptions in the determining PDE, it reduces to .. math:: f + (g - a)h - bh^{2} - (ax + by + c)\frac{\partial h}{\partial x} - (fx + gy + c)\frac{\partial h}{\partial y} Solving the reduced PDE obtained, using the method of characteristics, becomes impractical. The method followed is grouping similar terms and solving the system of linear equations obtained. The difference between the bivariate heuristic is that `h` need not be a rational function in this case. References ========== - E.S. Cheb-Terrab, A.D. Roche, Symmetries and First Order ODE Patterns, pp. 10 - pp. 12 """ xieta = [] h = match['h'] hx = match['hx'] hy = match['hy'] func = match['func'] hinv = match['hinv'] x = func.args[0] y = match['y'] xi = Function('xi')(x, func) eta = Function('eta')(x, func) coeffdict = {} symbols = numbered_symbols("c", cls=Dummy) symlist = [next(symbols) for i in islice(symbols, 6)] C0, C1, C2, C3, C4, C5 = symlist pde = C3 + (C4 - C0)h -(C0x + C1y + C2)hx - (C3x + C4y + C5)hy - C1h*2 pde, denom = pde.as_numer_denom() pde = powsimp(expand(pde)) if pde.is_Add: terms = pde.args for term in terms: if term.is_Mul: rem = Mul([m for m in term.args if not m.has(x, y)]) xypart = term/rem if xypart not in coeffdict: coeffdict[xypart] = rem else: coeffdict[xypart] += rem else: if term not in coeffdict: coeffdict[term] = S(1) else: coeffdict[term] += S(1) sollist = coeffdict.values() soldict = solve(sollist, symlist) if soldict: if isinstance(soldict, list): soldict = soldict[0] subval = soldict.values() if any(t for t in subval): onedict = dict(zip(symlist, [1]6)) xival = C0x + C1func + C2 etaval = C3x + C4func + C5 xival = xival.subs(soldict) etaval = etaval.subs(soldict) xival = xival.subs(onedict) etaval = etaval.subs(onedict) return [{xi: xival, eta: etaval}] def sysode_linear_2eq_order1(match_): x = match_['func'][0].func y = match_['func'][1].func func = match_['func'] fc = match_['func_coeff'] eq = match_['eq'] C1, C2, C3, C4 = get_numbered_constants(eq, num=4) r = dict() t = list(list(eq[0].atoms(Derivative))[0].atoms(Symbol))[0] for i in range(2): eqs = 0 for terms in Add.make_args(eq[i]): eqs += terms/fc[i,func[i],1] eq[i] = eqs # for equations Eq(a1diff(x(t),t), ax(t) + by(t) + k1) # and Eq(a2diff(x(t),t), cx(t) + dy(t) + k2) r['a'] = -fc[0,x(t),0]/fc[0,x(t),1] r['c'] = -fc[1,x(t),0]/fc[1,y(t),1] r['b'] = -fc[0,y(t),0]/fc[0,x(t),1] r['d'] = -fc[1,y(t),0]/fc[1,y(t),1] forcing = [S(0),S(0)] for i in range(2): for j in Add.make_args(eq[i]): if not j.has(x(t), y(t)): forcing[i] += j if not (forcing[0].has(t) or forcing[1].has(t)): r['k1'] = forcing[0] r['k2'] = forcing[1] else: raise NotImplementedError("Only homogeneous problems are supported" + " (and constant inhomogeneity)") if match_['type_of_equation'] == 'type1': sol = _linear_2eq_order1_type1(x, y, t, r, eq) if match_['type_of_equation'] == 'type2': gsol = _linear_2eq_order1_type1(x, y, t, r, eq) psol = _linear_2eq_order1_type2(x, y, t, r, eq) sol = [Eq(x(t), gsol[0].rhs+psol[0]), Eq(y(t), gsol[1].rhs+psol[1])] if match_['type_of_equation'] == 'type3': sol = _linear_2eq_order1_type3(x, y, t, r, eq) if match_['type_of_equation'] == 'type4': sol = _linear_2eq_order1_type4(x, y, t, r, eq) if match_['type_of_equation'] == 'type5': sol = _linear_2eq_order1_type5(x, y, t, r, eq) if match_['type_of_equation'] == 'type6': sol = _linear_2eq_order1_type6(x, y, t, r, eq) if match_['type_of_equation'] == 'type7': sol = _linear_2eq_order1_type7(x, y, t, r, eq) return sol def _linear_2eq_order1_type1(x, y, t, r, eq): r""" It is classified under system of two linear homogeneous first-order constant-coefficient ordinary differential equations. The equations which come under this type are .. math:: x' = ax + by, .. math:: y' = cx + dy The characteristics equation is written as .. math:: \lambda^{2} + (a+d) \lambda + ad - bc = 0 and its discriminant is `D = (a-d)^{2} + 4bc`. There are several cases 1. Case when `ad - bc \neq 0`. The origin of coordinates, `x = y = 0`, is the only stationary point; it is - a node if `D = 0` - a node if `D > 0` and `ad - bc > 0` - a saddle if `D > 0` and `ad - bc < 0` - a focus if `D < 0` and `a + d \neq 0` - a centre if `D < 0` and `a + d \neq 0`. 1.1. If `D > 0`. The characteristic equation has two distinct real roots `\lambda_1` and `\lambda_ 2` . The general solution of the system in question is expressed as .. math:: x = C_1 b e^{\lambda_1 t} + C_2 b e^{\lambda_2 t} .. math:: y = C_1 (\lambda_1 - a) e^{\lambda_1 t} + C_2 (\lambda_2 - a) e^{\lambda_2 t} where `C_1` and `C_2` being arbitrary constants 1.2. If `D < 0`. The characteristics equation has two conjugate roots, `\lambda_1 = \sigma + i \beta` and `\lambda_2 = \sigma - i \beta`. The general solution of the system is given by .. math:: x = b e^{\sigma t} (C_1 \sin(\beta t) + C_2 \cos(\beta t)) .. math:: y = e^{\sigma t} ([(\sigma - a) C_1 - \beta C_2] \sin(\beta t) + [\beta C_1 + (\sigma - a) C_2 \cos(\beta t)]) 1.3. If `D = 0` and `a \neq d`. The characteristic equation has two equal roots, `\lambda_1 = \lambda_2`. The general solution of the system is written as .. math:: x = 2b (C_1 + \frac{C_2}{a-d} + C_2 t) e^{\frac{a+d}{2} t} .. math:: y = [(d - a) C_1 + C_2 + (d - a) C_2 t] e^{\frac{a+d}{2} t} 1.4. If `D = 0` and `a = d \neq 0` and `b = 0` .. math:: x = C_1 e^{a t} , y = (c C_1 t + C_2) e^{a t} 1.5. If `D = 0` and `a = d \neq 0` and `c = 0` .. math:: x = (b C_1 t + C_2) e^{a t} , y = C_1 e^{a t} 2. Case when `ad - bc = 0` and `a^{2} + b^{2} > 0`. The whole straight line `ax + by = 0` consists of singular points. The original system of differential equations can be rewritten as .. math:: x' = ax + by , y' = k (ax + by) 2.1 If `a + bk \neq 0`, solution will be .. math:: x = b C_1 + C_2 e^{(a + bk) t} , y = -a C_1 + k C_2 e^{(a + bk) t} 2.2 If `a + bk = 0`, solution will be .. math:: x = C_1 (bk t - 1) + b C_2 t , y = k^{2} b C_1 t + (b k^{2} t + 1) C_2 """ l = Dummy('l') C1, C2 = get_numbered_constants(eq, num=2) a, b, c, d = r['a'], r['b'], r['c'], r['d'] real_coeff = all(v.is_real for v in (a, b, c, d)) D = (a - d)2 + 4bc l1 = (a + d + sqrt(D))/2 l2 = (a + d - sqrt(D))/2 equal_roots = Eq(D, 0).expand() gsol1, gsol2 = [], [] # Solutions have exponential form if either D > 0 with real coefficients # or D != 0 with complex coefficients. Eigenvalues are distinct. # For each eigenvalue lam, pick an eigenvector, making sure we don't get (0, 0) # The candidates are (b, lam-a) and (lam-d, c). exponential_form = D > 0 if real_coeff else Not(equal_roots) bad_ab_vector1 = And(Eq(b, 0), Eq(l1, a)) bad_ab_vector2 = And(Eq(b, 0), Eq(l2, a)) vector1 = Matrix((Piecewise((l1 - d, bad_ab_vector1), (b, True)), Piecewise((c, bad_ab_vector1), (l1 - a, True)))) vector2 = Matrix((Piecewise((l2 - d, bad_ab_vector2), (b, True)), Piecewise((c, bad_ab_vector2), (l2 - a, True)))) sol_vector = C1exp(l1t)vector1 + C2exp(l2t)vector2 gsol1.append((sol_vector[0], exponential_form)) gsol2.append((sol_vector[1], exponential_form)) # Solutions have trigonometric form for real coefficients with D < 0 # Both b and c are nonzero in this case, so (b, lam-a) is an eigenvector # It splits into real/imag parts as (b, sigma-a) and (0, beta). Then # multiply it by C1(cos(betat) + IC2sin(betat)) and separate real/imag trigonometric_form = D < 0 if real_coeff else False sigma = re(l1) if im(l1).is_positive: beta = im(l1) else: beta = im(l2) vector1 = Matrix((b, sigma - a)) vector2 = Matrix((0, beta)) sol_vector = exp(sigmat) * (C1(cos(betat)vector1 - sin(betat)vector2) + \ C2(sin(betat)vector1 + cos(betat)vector2)) gsol1.append((sol_vector[0], trigonometric_form)) gsol2.append((sol_vector[1], trigonometric_form)) # Final case is D == 0, a single eigenvalue. If the eigenspace is 2-dimensional # then we have a scalar matrix, deal with this case first. scalar_matrix = And(Eq(a, d), Eq(b, 0), Eq(c, 0)) vector1 = Matrix((S.One, S.Zero)) vector2 = Matrix((S.Zero, S.One)) sol_vector = exp(l1t) (C1vector1 + C2vector2) gsol1.append((sol_vector[0], scalar_matrix)) gsol2.append((sol_vector[1], scalar_matrix)) # Have one eigenvector. Get a generalized eigenvector from (A-lam)vector2 = vector1 vector1 = Matrix((Piecewise((l1 - d, bad_ab_vector1), (b, True)), Piecewise((c, bad_ab_vector1), (l1 - a, True)))) vector2 = Matrix((Piecewise((S.One, bad_ab_vector1), (S.Zero, Eq(a, l1)), (b/(a - l1), True)), Piecewise((S.Zero, bad_ab_vector1), (S.One, Eq(a, l1)), (S.Zero, True)))) sol_vector = exp(l1t) * (C1vector1 + C2(vector2 + tvector1)) gsol1.append((sol_vector[0], equal_roots)) gsol2.append((sol_vector[1], equal_roots)) return [Eq(x(t), Piecewise(gsol1)), Eq(y(t), Piecewise(gsol2))] def _linear_2eq_order1_type2(x, y, t, r, eq): r""" The equations of this type are .. math:: x' = ax + by + k1 , y' = cx + dy + k2 The general solution of this system is given by sum of its particular solution and the general solution of the corresponding homogeneous system is obtained from type1. 1. When `ad - bc \neq 0`. The particular solution will be `x = x_0` and `y = y_0` where `x_0` and `y_0` are determined by solving linear system of equations .. math:: a x_0 + b y_0 + k1 = 0 , c x_0 + d y_0 + k2 = 0 2. When `ad - bc = 0` and `a^{2} + b^{2} > 0`. In this case, the system of equation becomes .. math:: x' = ax + by + k_1 , y' = k (ax + by) + k_2 2.1 If `\sigma = a + bk \neq 0`, particular solution is given by .. math:: x = b \sigma^{-1} (c_1 k - c_2) t - \sigma^{-2} (a c_1 + b c_2) .. math:: y = kx + (c_2 - c_1 k) t 2.2 If `\sigma = a + bk = 0`, particular solution is given by .. math:: x = \frac{1}{2} b (c_2 - c_1 k) t^{2} + c_1 t .. math:: y = kx + (c_2 - c_1 k) t """ r['k1'] = -r['k1']; r['k2'] = -r['k2'] if (r['a']r['d'] - r['b']r['c']) != 0: x0, y0 = symbols('x0, y0', cls=Dummy) sol = solve((r['a']x0+r['b']y0+r['k1'], r['c']x0+r['d']y0+r['k2']), x0, y0) psol = [sol[x0], sol[y0]] elif (r['a']r['d'] - r['b']r['c']) == 0 and (r['a']2+r['b']2) > 0: k = r['c']/r['a'] sigma = r['a'] + r['b']k if sigma != 0: sol1 = r['b']sigma-1(r['k1']k-r['k2'])t - sigma*-2(r['a']r['k1']+r['b']r['k2']) sol2 = ksol1 + (r['k2']-r['k1']k)t else: # FIXME: a previous typo fix shows this is not covered by tests sol1 = r['b'](r['k2']-r['k1']k)t*2 + r['k1']t sol2 = ksol1 + (r['k2']-r['k1']k)t psol = [sol1, sol2] return psol def _linear_2eq_order1_type3(x, y, t, r, eq): r""" The equations of this type of ode are .. math:: x' = f(t) x + g(t) y .. math:: y' = g(t) x + f(t) y The solution of such equations is given by .. math:: x = e^{F} (C_1 e^{G} + C_2 e^{-G}) , y = e^{F} (C_1 e^{G} - C_2 e^{-G}) where `C_1` and `C_2` are arbitrary constants, and .. math:: F = \int f(t) \,dt , G = \int g(t) \,dt """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) F = Integral(r['a'], t) G = Integral(r['b'], t) sol1 = exp(F)(C1exp(G) + C2exp(-G)) sol2 = exp(F)(C1exp(G) - C2exp(-G)) return [Eq(x(t), sol1), Eq(y(t), sol2)] def _linear_2eq_order1_type4(x, y, t, r, eq): r""" The equations of this type of ode are . .. math:: x' = f(t) x + g(t) y .. math:: y' = -g(t) x + f(t) y The solution is given by .. math:: x = F (C_1 \cos(G) + C_2 \sin(G)), y = F (-C_1 \sin(G) + C_2 \cos(G)) where `C_1` and `C_2` are arbitrary constants, and .. math:: F = \int f(t) \,dt , G = \int g(t) \,dt """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) if r['b'] == -r['c']: F = exp(Integral(r['a'], t)) G = Integral(r['b'], t) sol1 = F(C1cos(G) + C2sin(G)) sol2 = F(-C1sin(G) + C2cos(G)) elif r['d'] == -r['a']: F = exp(Integral(r['c'], t)) G = Integral(r['d'], t) sol1 = F(-C1sin(G) + C2cos(G)) sol2 = F(C1cos(G) + C2sin(G)) return [Eq(x(t), sol1), Eq(y(t), sol2)] def _linear_2eq_order1_type5(x, y, t, r, eq): r""" The equations of this type of ode are . .. math:: x' = f(t) x + g(t) y .. math:: y' = a g(t) x + [f(t) + b g(t)] y The transformation of .. math:: x = e^{\int f(t) \,dt} u , y = e^{\int f(t) \,dt} v , T = \int g(t) \,dt leads to a system of constant coefficient linear differential equations .. math:: u'(T) = v , v'(T) = au + bv """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) u, v = symbols('u, v', cls=Function) T = Symbol('T') if not cancel(r['c']/r['b']).has(t): p = cancel(r['c']/r['b']) q = cancel((r['d']-r['a'])/r['b']) eq = (Eq(diff(u(T),T), v(T)), Eq(diff(v(T),T), pu(T)+qv(T))) sol = dsolve(eq) sol1 = exp(Integral(r['a'], t))sol[0].rhs.subs(T, Integral(r['b'],t)) sol2 = exp(Integral(r['a'], t))sol[1].rhs.subs(T, Integral(r['b'],t)) if not cancel(r['a']/r['d']).has(t): p = cancel(r['a']/r['d']) q = cancel((r['b']-r['c'])/r['d']) sol = dsolve(Eq(diff(u(T),T), v(T)), Eq(diff(v(T),T), pu(T)+qv(T))) sol1 = exp(Integral(r['c'], t))sol[1].rhs.subs(T, Integral(r['d'],t)) sol2 = exp(Integral(r['c'], t))sol[0].rhs.subs(T, Integral(r['d'],t)) return [Eq(x(t), sol1), Eq(y(t), sol2)] def _linear_2eq_order1_type6(x, y, t, r, eq): r""" The equations of this type of ode are . .. math:: x' = f(t) x + g(t) y .. math:: y' = a [f(t) + a h(t)] x + a [g(t) - h(t)] y This is solved by first multiplying the first equation by `-a` and adding it to the second equation to obtain .. math:: y' - a x' = -a h(t) (y - a x) Setting `U = y - ax` and integrating the equation we arrive at .. math:: y - ax = C_1 e^{-a \int h(t) \,dt} and on substituting the value of y in first equation give rise to first order ODEs. After solving for `x`, we can obtain `y` by substituting the value of `x` in second equation. """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) p = 0 q = 0 p1 = cancel(r['c']/cancel(r['c']/r['d']).as_numer_denom()[0]) p2 = cancel(r['a']/cancel(r['a']/r['b']).as_numer_denom()[0]) for n, i in enumerate([p1, p2]): for j in Mul.make_args(collect_const(i)): if not j.has(t): q = j if q!=0 and n==0: if ((r['c']/j - r['a'])/(r['b'] - r['d']/j)) == j: p = 1 s = j break if q!=0 and n==1: if ((r['a']/j - r['c'])/(r['d'] - r['b']/j)) == j: p = 2 s = j break if p == 1: equ = diff(x(t),t) - r['a']x(t) - r['b'](sx(t) + C1exp(-sIntegral(r['b'] - r['d']/s, t))) hint1 = classify_ode(equ)[1] sol1 = dsolve(equ, hint=hint1+'_Integral').rhs sol2 = ssol1 + C1exp(-sIntegral(r['b'] - r['d']/s, t)) elif p ==2: equ = diff(y(t),t) - r['c']y(t) - r['d']sy(t) + C1exp(-sIntegral(r['d'] - r['b']/s, t)) hint1 = classify_ode(equ)[1] sol2 = dsolve(equ, hint=hint1+'_Integral').rhs sol1 = ssol2 + C1exp(-sIntegral(r['d'] - r['b']/s, t)) return [Eq(x(t), sol1), Eq(y(t), sol2)] def _linear_2eq_order1_type7(x, y, t, r, eq): r""" The equations of this type of ode are . .. math:: x' = f(t) x + g(t) y .. math:: y' = h(t) x + p(t) y Differentiating the first equation and substituting the value of `y` from second equation will give a second-order linear equation .. math:: g x'' - (fg + gp + g') x' + (fgp - g^{2} h + f g' - f' g) x = 0 This above equation can be easily integrated if following conditions are satisfied. 1. `fgp - g^{2} h + f g' - f' g = 0` 2. `fgp - g^{2} h + f g' - f' g = ag, fg + gp + g' = bg` If first condition is satisfied then it is solved by current dsolve solver and in second case it becomes a constant coefficient differential equation which is also solved by current solver. Otherwise if the above condition fails then, a particular solution is assumed as `x = x_0(t)` and `y = y_0(t)` Then the general solution is expressed as .. math:: x = C_1 x_0(t) + C_2 x_0(t) \int \frac{g(t) F(t) P(t)}{x_0^{2}(t)} \,dt .. math:: y = C_1 y_0(t) + C_2 [\frac{F(t) P(t)}{x_0(t)} + y_0(t) \int \frac{g(t) F(t) P(t)}{x_0^{2}(t)} \,dt] where C1 and C2 are arbitrary constants and .. math:: F(t) = e^{\int f(t) \,dt} , P(t) = e^{\int p(t) \,dt} """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) e1 = r['a']r['b']r['c'] - r['b']2r['c'] + r['a']diff(r['b'],t) - diff(r['a'],t)r['b'] e2 = r['a']r['c']r['d'] - r['b']r['c']2 + diff(r['c'],t)r['d'] - r['c']diff(r['d'],t) m1 = r['a']r['b'] + r['b']r['d'] + diff(r['b'],t) m2 = r['a']r['c'] + r['c']r['d'] + diff(r['c'],t) if e1 == 0: sol1 = dsolve(r['b']diff(x(t),t,t) - m1diff(x(t),t)).rhs sol2 = dsolve(diff(y(t),t) - r['c']sol1 - r['d']y(t)).rhs elif e2 == 0: sol2 = dsolve(r['c']diff(y(t),t,t) - m2diff(y(t),t)).rhs sol1 = dsolve(diff(x(t),t) - r['a']x(t) - r['b']sol2).rhs elif not (e1/r['b']).has(t) and not (m1/r['b']).has(t): sol1 = dsolve(diff(x(t),t,t) - (m1/r['b'])diff(x(t),t) - (e1/r['b'])x(t)).rhs sol2 = dsolve(diff(y(t),t) - r['c']sol1 - r['d']y(t)).rhs elif not (e2/r['c']).has(t) and not (m2/r['c']).has(t): sol2 = dsolve(diff(y(t),t,t) - (m2/r['c'])diff(y(t),t) - (e2/r['c'])y(t)).rhs sol1 = dsolve(diff(x(t),t) - r['a']x(t) - r['b']sol2).rhs else: x0 = Function('x0')(t) # x0 and y0 being particular solutions y0 = Function('y0')(t) F = exp(Integral(r['a'],t)) P = exp(Integral(r['d'],t)) sol1 = C1x0 + C2x0Integral(r['b']FP/x0*2, t) sol2 = C1y0 + C2(FP/x0 + y0Integral(r['b']FP/x02, t)) return [Eq(x(t), sol1), Eq(y(t), sol2)] def sysode_linear_2eq_order2(match_): x = match_['func'][0].func y = match_['func'][1].func func = match_['func'] fc = match_['func_coeff'] eq = match_['eq'] C1, C2, C3, C4 = get_numbered_constants(eq, num=4) r = dict() t = list(list(eq[0].atoms(Derivative))[0].atoms(Symbol))[0] for i in range(2): eqs = [] for terms in Add.make_args(eq[i]): eqs.append(terms/fc[i,func[i],2]) eq[i] = Add(eqs) # for equations Eq(diff(x(t),t,t), a1diff(x(t),t)+b1diff(y(t),t)+c1x(t)+d1y(t)+e1) # and Eq(a2diff(y(t),t,t), a2diff(x(t),t)+b2diff(y(t),t)+c2x(t)+d2y(t)+e2) r['a1'] = -fc[0,x(t),1]/fc[0,x(t),2] ; r['a2'] = -fc[1,x(t),1]/fc[1,y(t),2] r['b1'] = -fc[0,y(t),1]/fc[0,x(t),2] ; r['b2'] = -fc[1,y(t),1]/fc[1,y(t),2] r['c1'] = -fc[0,x(t),0]/fc[0,x(t),2] ; r['c2'] = -fc[1,x(t),0]/fc[1,y(t),2] r['d1'] = -fc[0,y(t),0]/fc[0,x(t),2] ; r['d2'] = -fc[1,y(t),0]/fc[1,y(t),2] const = [S(0), S(0)] for i in range(2): for j in Add.make_args(eq[i]): if not (j.has(x(t)) or j.has(y(t))): const[i] += j r['e1'] = -const[0] r['e2'] = -const[1] if match_['type_of_equation'] == 'type1': sol = _linear_2eq_order2_type1(x, y, t, r, eq) elif match_['type_of_equation'] == 'type2': gsol = _linear_2eq_order2_type1(x, y, t, r, eq) psol = _linear_2eq_order2_type2(x, y, t, r, eq) sol = [Eq(x(t), gsol[0].rhs+psol[0]), Eq(y(t), gsol[1].rhs+psol[1])] elif match_['type_of_equation'] == 'type3': sol = _linear_2eq_order2_type3(x, y, t, r, eq) elif match_['type_of_equation'] == 'type4': sol = _linear_2eq_order2_type4(x, y, t, r, eq) elif match_['type_of_equation'] == 'type5': sol = _linear_2eq_order2_type5(x, y, t, r, eq) elif match_['type_of_equation'] == 'type6': sol = _linear_2eq_order2_type6(x, y, t, r, eq) elif match_['type_of_equation'] == 'type7': sol = _linear_2eq_order2_type7(x, y, t, r, eq) elif match_['type_of_equation'] == 'type8': sol = _linear_2eq_order2_type8(x, y, t, r, eq) elif match_['type_of_equation'] == 'type9': sol = _linear_2eq_order2_type9(x, y, t, r, eq) elif match_['type_of_equation'] == 'type10': sol = _linear_2eq_order2_type10(x, y, t, r, eq) elif match_['type_of_equation'] == 'type11': sol = _linear_2eq_order2_type11(x, y, t, r, eq) return sol def _linear_2eq_order2_type1(x, y, t, r, eq): r""" System of two constant-coefficient second-order linear homogeneous differential equations .. math:: x'' = ax + by .. math:: y'' = cx + dy The characteristic equation for above equations .. math:: \lambda^4 - (a + d) \lambda^2 + ad - bc = 0 whose discriminant is `D = (a - d)^2 + 4bc \neq 0` 1. When `ad - bc \neq 0` 1.1. If `D \neq 0`. The characteristic equation has four distinct roots, `\lambda_1, \lambda_2, \lambda_3, \lambda_4`. The general solution of the system is .. math:: x = C_1 b e^{\lambda_1 t} + C_2 b e^{\lambda_2 t} + C_3 b e^{\lambda_3 t} + C_4 b e^{\lambda_4 t} .. math:: y = C_1 (\lambda_1^{2} - a) e^{\lambda_1 t} + C_2 (\lambda_2^{2} - a) e^{\lambda_2 t} + C_3 (\lambda_3^{2} - a) e^{\lambda_3 t} + C_4 (\lambda_4^{2} - a) e^{\lambda_4 t} where `C_1,..., C_4` are arbitrary constants. 1.2. If `D = 0` and `a \neq d`: .. math:: x = 2 C_1 (bt + \frac{2bk}{a - d}) e^{\frac{kt}{2}} + 2 C_2 (bt + \frac{2bk}{a - d}) e^{\frac{-kt}{2}} + 2b C_3 t e^{\frac{kt}{2}} + 2b C_4 t e^{\frac{-kt}{2}} .. math:: y = C_1 (d - a) t e^{\frac{kt}{2}} + C_2 (d - a) t e^{\frac{-kt}{2}} + C_3 [(d - a) t + 2k] e^{\frac{kt}{2}} + C_4 [(d - a) t - 2k] e^{\frac{-kt}{2}} where `C_1,..., C_4` are arbitrary constants and `k = \sqrt{2 (a + d)}` 1.3. If `D = 0` and `a = d \neq 0` and `b = 0`: .. math:: x = 2 \sqrt{a} C_1 e^{\sqrt{a} t} + 2 \sqrt{a} C_2 e^{-\sqrt{a} t} .. math:: y = c C_1 t e^{\sqrt{a} t} - c C_2 t e^{-\sqrt{a} t} + C_3 e^{\sqrt{a} t} + C_4 e^{-\sqrt{a} t} 1.4. If `D = 0` and `a = d \neq 0` and `c = 0`: .. math:: x = b C_1 t e^{\sqrt{a} t} - b C_2 t e^{-\sqrt{a} t} + C_3 e^{\sqrt{a} t} + C_4 e^{-\sqrt{a} t} .. math:: y = 2 \sqrt{a} C_1 e^{\sqrt{a} t} + 2 \sqrt{a} C_2 e^{-\sqrt{a} t} 2. When `ad - bc = 0` and `a^2 + b^2 > 0`. Then the original system becomes .. math:: x'' = ax + by .. math:: y'' = k (ax + by) 2.1. If `a + bk \neq 0`: .. math:: x = C_1 e^{t \sqrt{a + bk}} + C_2 e^{-t \sqrt{a + bk}} + C_3 bt + C_4 b .. math:: y = C_1 k e^{t \sqrt{a + bk}} + C_2 k e^{-t \sqrt{a + bk}} - C_3 at - C_4 a 2.2. If `a + bk = 0`: .. math:: x = C_1 b t^3 + C_2 b t^2 + C_3 t + C_4 .. math:: y = kx + 6 C_1 t + 2 C_2 """ r['a'] = r['c1'] r['b'] = r['d1'] r['c'] = r['c2'] r['d'] = r['d2'] l = Symbol('l') C1, C2, C3, C4 = get_numbered_constants(eq, num=4) chara_eq = l4 - (r['a']+r['d'])l*2 + r['a']r['d'] - r['b']r['c'] l1 = rootof(chara_eq, 0) l2 = rootof(chara_eq, 1) l3 = rootof(chara_eq, 2) l4 = rootof(chara_eq, 3) D = (r['a'] - r['d'])2 + 4r['b']r['c'] if (r['a']r['d'] - r['b']r['c']) != 0: if D != 0: gsol1 = C1r['b']exp(l1t) + C2r['b']exp(l2t) + C3r['b']exp(l3t) \ + C4r['b']exp(l4t) gsol2 = C1(l1*2-r['a'])exp(l1t) + C2(l2*2-r['a'])exp(l2t) + \ C3(l3*2-r['a'])exp(l3t) + C4(l4*2-r['a'])exp(l4t) else: if r['a'] != r['d']: k = sqrt(2(r['a']+r['d'])) mid = r['b']t+2r['b']k/(r['a']-r['d']) gsol1 = 2C1midexp(kt/2) + 2C2midexp(-kt/2) + \ 2r['b']C3texp(kt/2) + 2r['b']C4texp(-kt/2) gsol2 = C1(r['d']-r['a'])texp(kt/2) + C2(r['d']-r['a'])texp(-kt/2) + \ C3((r['d']-r['a'])t+2k)exp(kt/2) + C4((r['d']-r['a'])t-2k)exp(-kt/2) elif r['a'] == r['d'] != 0 and r['b'] == 0: sa = sqrt(r['a']) gsol1 = 2saC1exp(sat) + 2saC2exp(-sat) gsol2 = r['c']C1texp(sat)-r['c']C2texp(-sat)+C3exp(sat)+C4exp(-sat) elif r['a'] == r['d'] != 0 and r['c'] == 0: sa = sqrt(r['a']) gsol1 = r['b']C1texp(sat)-r['b']C2texp(-sat)+C3exp(sat)+C4exp(-sat) gsol2 = 2saC1exp(sat) + 2saC2exp(-sat) elif (r['a']r['d'] - r['b']r['c']) == 0 and (r['a']2 + r['b']2) > 0: k = r['c']/r['a'] if r['a'] + r['b']k != 0: mid = sqrt(r['a'] + r['b']k) gsol1 = C1exp(midt) + C2exp(-midt) + C3r['b']t + C4r['b'] gsol2 = C1kexp(midt) + C2kexp(-midt) - C3r['a']t - C4r['a'] else: gsol1 = C1r['b']t3 + C2r['b']t2 + C3t + C4 gsol2 = kgsol1 + 6C1t + 2C2 return [Eq(x(t), gsol1), Eq(y(t), gsol2)] def _linear_2eq_order2_type2(x, y, t, r, eq): r""" The equations in this type are .. math:: x'' = a_1 x + b_1 y + c_1 .. math:: y'' = a_2 x + b_2 y + c_2 The general solution of this system is given by the sum of its particular solution and the general solution of the homogeneous system. The general solution is given by the linear system of 2 equation of order 2 and type 1 1. If `a_1 b_2 - a_2 b_1 \neq 0`. A particular solution will be `x = x_0` and `y = y_0` where the constants `x_0` and `y_0` are determined by solving the linear algebraic system .. math:: a_1 x_0 + b_1 y_0 + c_1 = 0, a_2 x_0 + b_2 y_0 + c_2 = 0 2. If `a_1 b_2 - a_2 b_1 = 0` and `a_1^2 + b_1^2 > 0`. In this case, the system in question becomes .. math:: x'' = ax + by + c_1, y'' = k (ax + by) + c_2 2.1. If `\sigma = a + bk \neq 0`, the particular solution will be .. math:: x = \frac{1}{2} b \sigma^{-1} (c_1 k - c_2) t^2 - \sigma^{-2} (a c_1 + b c_2) .. math:: y = kx + \frac{1}{2} (c_2 - c_1 k) t^2 2.2. If `\sigma = a + bk = 0`, the particular solution will be .. math:: x = \frac{1}{24} b (c_2 - c_1 k) t^4 + \frac{1}{2} c_1 t^2 .. math:: y = kx + \frac{1}{2} (c_2 - c_1 k) t^2 """ x0, y0 = symbols('x0, y0') if r['c1']r['d2'] - r['c2']r['d1'] != 0: sol = solve((r['c1']x0+r['d1']y0+r['e1'], r['c2']x0+r['d2']y0+r['e2']), x0, y0) psol = [sol[x0], sol[y0]] elif r['c1']r['d2'] - r['c2']r['d1'] == 0 and (r['c1']2 + r['d1']2) > 0: k = r['c2']/r['c1'] sig = r['c1'] + r['d1']k if sig != 0: psol1 = r['d1']sig*-1(r['e1']k-r['e2'])t2/2 - \ sig-2(r['c1']r['e1']+r['d1']r['e2']) psol2 = kpsol1 + (r['e2'] - r['e1']k)t*2/2 psol = [psol1, psol2] else: psol1 = r['d1'](r['e2']-r['e1']k)t*4/24 + r['e1']t*2/2 psol2 = kpsol1 + (r['e2']-r['e1']k)t2/2 psol = [psol1, psol2] return psol def _linear_2eq_order2_type3(x, y, t, r, eq): r""" These type of equation is used for describing the horizontal motion of a pendulum taking into account the Earth rotation. The solution is given with `a^2 + 4b > 0`: .. math:: x = C_1 \cos(\alpha t) + C_2 \sin(\alpha t) + C_3 \cos(\beta t) + C_4 \sin(\beta t) .. math:: y = -C_1 \sin(\alpha t) + C_2 \cos(\alpha t) - C_3 \sin(\beta t) + C_4 \cos(\beta t) where `C_1,...,C_4` and .. math:: \alpha = \frac{1}{2} a + \frac{1}{2} \sqrt{a^2 + 4b}, \beta = \frac{1}{2} a - \frac{1}{2} \sqrt{a^2 + 4b} """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) if r['b1']2 - 4r['c1'] > 0: r['a'] = r['b1'] ; r['b'] = -r['c1'] alpha = r['a']/2 + sqrt(r['a']2 + 4r['b'])/2 beta = r['a']/2 - sqrt(r['a']*2 + 4r['b'])/2 sol1 = C1cos(alphat) + C2sin(alphat) + C3cos(betat) + C4sin(betat) sol2 = -C1sin(alphat) + C2cos(alphat) - C3sin(betat) + C4cos(betat) return [Eq(x(t), sol1), Eq(y(t), sol2)] def _linear_2eq_order2_type4(x, y, t, r, eq): r""" These equations are found in the theory of oscillations .. math:: x'' + a_1 x' + b_1 y' + c_1 x + d_1 y = k_1 e^{i \omega t} .. math:: y'' + a_2 x' + b_2 y' + c_2 x + d_2 y = k_2 e^{i \omega t} The general solution of this linear nonhomogeneous system of constant-coefficient differential equations is given by the sum of its particular solution and the general solution of the corresponding homogeneous system (with `k_1 = k_2 = 0`) 1. A particular solution is obtained by the method of undetermined coefficients: .. math:: x = A_* e^{i \omega t}, y = B_* e^{i \omega t} On substituting these expressions into the original system of differential equations, one arrive at a linear nonhomogeneous system of algebraic equations for the coefficients `A` and `B`. 2. The general solution of the homogeneous system of differential equations is determined by a linear combination of linearly independent particular solutions determined by the method of undetermined coefficients in the form of exponentials: .. math:: x = A e^{\lambda t}, y = B e^{\lambda t} On substituting these expressions into the original system and collecting the coefficients of the unknown `A` and `B`, one obtains .. math:: (\lambda^{2} + a_1 \lambda + c_1) A + (b_1 \lambda + d_1) B = 0 .. math:: (a_2 \lambda + c_2) A + (\lambda^{2} + b_2 \lambda + d_2) B = 0 The determinant of this system must vanish for nontrivial solutions A, B to exist. This requirement results in the following characteristic equation for `\lambda` .. math:: (\lambda^2 + a_1 \lambda + c_1) (\lambda^2 + b_2 \lambda + d_2) - (b_1 \lambda + d_1) (a_2 \lambda + c_2) = 0 If all roots `k_1,...,k_4` of this equation are distinct, the general solution of the original system of the differential equations has the form .. math:: x = C_1 (b_1 \lambda_1 + d_1) e^{\lambda_1 t} - C_2 (b_1 \lambda_2 + d_1) e^{\lambda_2 t} - C_3 (b_1 \lambda_3 + d_1) e^{\lambda_3 t} - C_4 (b_1 \lambda_4 + d_1) e^{\lambda_4 t} .. math:: y = C_1 (\lambda_1^{2} + a_1 \lambda_1 + c_1) e^{\lambda_1 t} + C_2 (\lambda_2^{2} + a_1 \lambda_2 + c_1) e^{\lambda_2 t} + C_3 (\lambda_3^{2} + a_1 \lambda_3 + c_1) e^{\lambda_3 t} + C_4 (\lambda_4^{2} + a_1 \lambda_4 + c_1) e^{\lambda_4 t} """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) k = Symbol('k') Ra, Ca, Rb, Cb = symbols('Ra, Ca, Rb, Cb') a1 = r['a1'] ; a2 = r['a2'] b1 = r['b1'] ; b2 = r['b2'] c1 = r['c1'] ; c2 = r['c2'] d1 = r['d1'] ; d2 = r['d2'] k1 = r['e1'].expand().as_independent(t)[0] k2 = r['e2'].expand().as_independent(t)[0] ew1 = r['e1'].expand().as_independent(t)[1] ew2 = powdenest(ew1).as_base_exp()[1] ew3 = collect(ew2, t).coeff(t) w = cancel(ew3/I) # The particular solution is assumed to be (Ra+ICa)exp(Iwt) and # (Rb+ICb)exp(Iwt) for x(t) and y(t) respectively peq1 = (-w*2+c1)Ra - a1wCa + d1Rb - b1wCb - k1 peq2 = a1wRa + (-w2+c1)Ca + b1wRb + d1Cb peq3 = c2Ra - a2wCa + (-w*2+d2)Rb - b2wCb - k2 peq4 = a2wRa + c2Ca + b2wRb + (-w2+d2)Cb # FIXME: solve for what in what? Ra, Rb, etc I guess # but then psol not used for anything? psol = solve([peq1, peq2, peq3, peq4]) chareq = (k*2+a1k+c1)(k2+b2k+d2) - (b1k+d1)(a2k+c2) [k1, k2, k3, k4] = roots_quartic(Poly(chareq)) sol1 = -C1(b1k1+d1)exp(k1t) - C2(b1k2+d1)exp(k2t) - \ C3(b1k3+d1)exp(k3t) - C4(b1k4+d1)exp(k4t) + (Ra+ICa)exp(Iwt) a1_ = (a1-1) sol2 = C1(k1*2+a1_k1+c1)exp(k1t) + C2(k22+a1_k2+c1)exp(k2t) + \ C3(k32+a1_k3+c1)exp(k3t) + C4(k42+a1_k4+c1)exp(k4t) + (Rb+ICb)exp(Iwt) return [Eq(x(t), sol1), Eq(y(t), sol2)] def _linear_2eq_order2_type5(x, y, t, r, eq): r""" The equation which come under this category are .. math:: x'' = a (t y' - y) .. math:: y'' = b (t x' - x) The transformation .. math:: u = t x' - x, b = t y' - y leads to the first-order system .. math:: u' = atv, v' = btu The general solution of this system is given by If `ab > 0`: .. math:: u = C_1 a e^{\frac{1}{2} \sqrt{ab} t^2} + C_2 a e^{-\frac{1}{2} \sqrt{ab} t^2} .. math:: v = C_1 \sqrt{ab} e^{\frac{1}{2} \sqrt{ab} t^2} - C_2 \sqrt{ab} e^{-\frac{1}{2} \sqrt{ab} t^2} If `ab < 0`: .. math:: u = C_1 a \cos(\frac{1}{2} \sqrt{\left\|ab\right\|} t^2) + C_2 a \sin(-\frac{1}{2} \sqrt{\left\|ab\right\|} t^2) .. math:: v = C_1 \sqrt{\left\|ab\right\|} \sin(\frac{1}{2} \sqrt{\left\|ab\right\|} t^2) + C_2 \sqrt{\left\|ab\right\|} \cos(-\frac{1}{2} \sqrt{\left\|ab\right\|} t^2) where `C_1` and `C_2` are arbitrary constants. On substituting the value of `u` and `v` in above equations and integrating the resulting expressions, the general solution will become .. math:: x = C_3 t + t \int \frac{u}{t^2} \,dt, y = C_4 t + t \int \frac{u}{t^2} \,dt where `C_3` and `C_4` are arbitrary constants. """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) r['a'] = -r['d1'] ; r['b'] = -r['c2'] mul = sqrt(abs(r['a']r['b'])) if r['a']r['b'] > 0: u = C1r['a']exp(mult2/2) + C2r['a']exp(-mult*2/2) v = C1mulexp(mult*2/2) - C2mulexp(-mult*2/2) else: u = C1r['a']cos(mult*2/2) + C2r['a']sin(mult*2/2) v = -C1mulsin(mult*2/2) + C2mulcos(mult*2/2) sol1 = C3t + tIntegral(u/t2, t) sol2 = C4t + tIntegral(v/t2, t) return [Eq(x(t), sol1), Eq(y(t), sol2)] def _linear_2eq_order2_type6(x, y, t, r, eq): r""" The equations are .. math:: x'' = f(t) (a_1 x + b_1 y) .. math:: y'' = f(t) (a_2 x + b_2 y) If `k_1` and `k_2` are roots of the quadratic equation .. math:: k^2 - (a_1 + b_2) k + a_1 b_2 - a_2 b_1 = 0 Then by multiplying appropriate constants and adding together original equations we obtain two independent equations: .. math:: z_1'' = k_1 f(t) z_1, z_1 = a_2 x + (k_1 - a_1) y .. math:: z_2'' = k_2 f(t) z_2, z_2 = a_2 x + (k_2 - a_1) y Solving the equations will give the values of `x` and `y` after obtaining the value of `z_1` and `z_2` by solving the differential equation and substituting the result. """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) k = Symbol('k') z = Function('z') num, den = cancel( (r['c1']x(t) + r['d1']y(t))/ (r['c2']x(t) + r['d2']y(t))).as_numer_denom() f = r['c1']/num.coeff(x(t)) a1 = num.coeff(x(t)) b1 = num.coeff(y(t)) a2 = den.coeff(x(t)) b2 = den.coeff(y(t)) chareq = k2 - (a1 + b2)k + a1b2 - a2b1 k1, k2 = [rootof(chareq, k) for k in range(Poly(chareq).degree())] z1 = dsolve(diff(z(t),t,t) - k1fz(t)).rhs z2 = dsolve(diff(z(t),t,t) - k2fz(t)).rhs sol1 = (k1z2 - k2z1 + a1(z1 - z2))/(a2(k1-k2)) sol2 = (z1 - z2)/(k1 - k2) return [Eq(x(t), sol1), Eq(y(t), sol2)] def _linear_2eq_order2_type7(x, y, t, r, eq): r""" The equations are given as .. math:: x'' = f(t) (a_1 x' + b_1 y') .. math:: y'' = f(t) (a_2 x' + b_2 y') If `k_1` and 'k_2` are roots of the quadratic equation .. math:: k^2 - (a_1 + b_2) k + a_1 b_2 - a_2 b_1 = 0 Then the system can be reduced by adding together the two equations multiplied by appropriate constants give following two independent equations: .. math:: z_1'' = k_1 f(t) z_1', z_1 = a_2 x + (k_1 - a_1) y .. math:: z_2'' = k_2 f(t) z_2', z_2 = a_2 x + (k_2 - a_1) y Integrating these and returning to the original variables, one arrives at a linear algebraic system for the unknowns `x` and `y`: .. math:: a_2 x + (k_1 - a_1) y = C_1 \int e^{k_1 F(t)} \,dt + C_2 .. math:: a_2 x + (k_2 - a_1) y = C_3 \int e^{k_2 F(t)} \,dt + C_4 where `C_1,...,C_4` are arbitrary constants and `F(t) = \int f(t) \,dt` """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) k = Symbol('k') num, den = cancel( (r['a1']x(t) + r['b1']y(t))/ (r['a2']x(t) + r['b2']y(t))).as_numer_denom() f = r['a1']/num.coeff(x(t)) a1 = num.coeff(x(t)) b1 = num.coeff(y(t)) a2 = den.coeff(x(t)) b2 = den.coeff(y(t)) chareq = k*2 - (a1 + b2)k + a1b2 - a2b1 [k1, k2] = [rootof(chareq, k) for k in range(Poly(chareq).degree())] F = Integral(f, t) z1 = C1Integral(exp(k1F), t) + C2 z2 = C3Integral(exp(k2F), t) + C4 sol1 = (k1z2 - k2z1 + a1(z1 - z2))/(a2(k1-k2)) sol2 = (z1 - z2)/(k1 - k2) return [Eq(x(t), sol1), Eq(y(t), sol2)] def _linear_2eq_order2_type8(x, y, t, r, eq): r""" The equation of this category are .. math:: x'' = a f(t) (t y' - y) .. math:: y'' = b f(t) (t x' - x) The transformation .. math:: u = t x' - x, v = t y' - y leads to the system of first-order equations .. math:: u' = a t f(t) v, v' = b t f(t) u The general solution of this system has the form If `ab > 0`: .. math:: u = C_1 a e^{\sqrt{ab} \int t f(t) \,dt} + C_2 a e^{-\sqrt{ab} \int t f(t) \,dt} .. math:: v = C_1 \sqrt{ab} e^{\sqrt{ab} \int t f(t) \,dt} - C_2 \sqrt{ab} e^{-\sqrt{ab} \int t f(t) \,dt} If `ab < 0`: .. math:: u = C_1 a \cos(\sqrt{\left\|ab\right\|} \int t f(t) \,dt) + C_2 a \sin(-\sqrt{\left\|ab\right\|} \int t f(t) \,dt) .. math:: v = C_1 \sqrt{\left\|ab\right\|} \sin(\sqrt{\left\|ab\right\|} \int t f(t) \,dt) + C_2 \sqrt{\left\|ab\right\|} \cos(-\sqrt{\left\|ab\right\|} \int t f(t) \,dt) where `C_1` and `C_2` are arbitrary constants. On substituting the value of `u` and `v` in above equations and integrating the resulting expressions, the general solution will become .. math:: x = C_3 t + t \int \frac{u}{t^2} \,dt, y = C_4 t + t \int \frac{u}{t^2} \,dt where `C_3` and `C_4` are arbitrary constants. """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) num, den = cancel(r['d1']/r['c2']).as_numer_denom() f = -r['d1']/num a = num b = den mul = sqrt(abs(ab)) Igral = Integral(tf, t) if ab > 0: u = C1aexp(mulIgral) + C2aexp(-mulIgral) v = C1mulexp(mulIgral) - C2mulexp(-mulIgral) else: u = C1acos(mulIgral) + C2asin(mulIgral) v = -C1mulsin(mulIgral) + C2mulcos(mulIgral) sol1 = C3t + tIntegral(u/t2, t) sol2 = C4t + tIntegral(v/t2, t) return [Eq(x(t), sol1), Eq(y(t), sol2)] def _linear_2eq_order2_type9(x, y, t, r, eq): r""" .. math:: t^2 x'' + a_1 t x' + b_1 t y' + c_1 x + d_1 y = 0 .. math:: t^2 y'' + a_2 t x' + b_2 t y' + c_2 x + d_2 y = 0 These system of equations are euler type. The substitution of `t = \sigma e^{\tau} (\sigma \neq 0)` leads to the system of constant coefficient linear differential equations .. math:: x'' + (a_1 - 1) x' + b_1 y' + c_1 x + d_1 y = 0 .. math:: y'' + a_2 x' + (b_2 - 1) y' + c_2 x + d_2 y = 0 The general solution of the homogeneous system of differential equations is determined by a linear combination of linearly independent particular solutions determined by the method of undetermined coefficients in the form of exponentials .. math:: x = A e^{\lambda t}, y = B e^{\lambda t} On substituting these expressions into the original system and collecting the coefficients of the unknown `A` and `B`, one obtains .. math:: (\lambda^{2} + (a_1 - 1) \lambda + c_1) A + (b_1 \lambda + d_1) B = 0 .. math:: (a_2 \lambda + c_2) A + (\lambda^{2} + (b_2 - 1) \lambda + d_2) B = 0 The determinant of this system must vanish for nontrivial solutions A, B to exist. This requirement results in the following characteristic equation for `\lambda` .. math:: (\lambda^2 + (a_1 - 1) \lambda + c_1) (\lambda^2 + (b_2 - 1) \lambda + d_2) - (b_1 \lambda + d_1) (a_2 \lambda + c_2) = 0 If all roots `k_1,...,k_4` of this equation are distinct, the general solution of the original system of the differential equations has the form .. math:: x = C_1 (b_1 \lambda_1 + d_1) e^{\lambda_1 t} - C_2 (b_1 \lambda_2 + d_1) e^{\lambda_2 t} - C_3 (b_1 \lambda_3 + d_1) e^{\lambda_3 t} - C_4 (b_1 \lambda_4 + d_1) e^{\lambda_4 t} .. math:: y = C_1 (\lambda_1^{2} + (a_1 - 1) \lambda_1 + c_1) e^{\lambda_1 t} + C_2 (\lambda_2^{2} + (a_1 - 1) \lambda_2 + c_1) e^{\lambda_2 t} + C_3 (\lambda_3^{2} + (a_1 - 1) \lambda_3 + c_1) e^{\lambda_3 t} + C_4 (\lambda_4^{2} + (a_1 - 1) \lambda_4 + c_1) e^{\lambda_4 t} """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) k = Symbol('k') a1 = -r['a1']t; a2 = -r['a2']t b1 = -r['b1']t; b2 = -r['b2']t c1 = -r['c1']t*2; c2 = -r['c2']t*2 d1 = -r['d1']t*2; d2 = -r['d2']t2 eq = (k2+(a1-1)k+c1)(k*2+(b2-1)k+d2)-(b1k+d1)(a2k+c2) [k1, k2, k3, k4] = roots_quartic(Poly(eq)) sol1 = -C1(b1k1+d1)exp(k1log(t)) - C2(b1k2+d1)exp(k2log(t)) - \ C3(b1k3+d1)exp(k3log(t)) - C4(b1k4+d1)exp(k4log(t)) a1_ = (a1-1) sol2 = C1(k1*2+a1_k1+c1)exp(k1log(t)) + C2(k22+a1_k2+c1)exp(k2log(t)) \ + C3(k32+a1_k3+c1)exp(k3log(t)) + C4(k42+a1_k4+c1)exp(k4log(t)) return [Eq(x(t), sol1), Eq(y(t), sol2)] def _linear_2eq_order2_type10(x, y, t, r, eq): r""" The equation of this category are .. math:: (\alpha t^2 + \beta t + \gamma)^{2} x'' = ax + by .. math:: (\alpha t^2 + \beta t + \gamma)^{2} y'' = cx + dy The transformation .. math:: \tau = \int \frac{1}{\alpha t^2 + \beta t + \gamma} \,dt , u = \frac{x}{\sqrt{\left\|\alpha t^2 + \beta t + \gamma\right\|}} , v = \frac{y}{\sqrt{\left\|\alpha t^2 + \beta t + \gamma\right\|}} leads to a constant coefficient linear system of equations .. math:: u'' = (a - \alpha \gamma + \frac{1}{4} \beta^{2}) u + b v .. math:: v'' = c u + (d - \alpha \gamma + \frac{1}{4} \beta^{2}) v These system of equations obtained can be solved by type1 of System of two constant-coefficient second-order linear homogeneous differential equations. """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) u, v = symbols('u, v', cls=Function) assert False T = Symbol('T') p = Wild('p', exclude=[t, t2]) q = Wild('q', exclude=[t, t2]) s = Wild('s', exclude=[t, t2]) n = Wild('n', exclude=[t, t2]) num, den = r['c1'].as_numer_denom() dic = den.match((n(pt*2+qt+s)*2).expand()) eqz = dic[p]t*2 + dic[q]t + dic[s] a = num/dic[n] b = cancel(r['d1']eqz2) c = cancel(r['c2']eqz*2) d = cancel(r['d2']eqz*2) [msol1, msol2] = dsolve([Eq(diff(u(t), t, t), (a - dic[p]dic[s] + dic[q]*2/4)u(t) \ + bv(t)), Eq(diff(v(t),t,t), cu(t) + (d - dic[p]dic[s] + dic[q]2/4)v(t))]) sol1 = (msol1.rhssqrt(abs(eqz))).subs(t, Integral(1/eqz, t)) sol2 = (msol2.rhssqrt(abs(eqz))).subs(t, Integral(1/eqz, t)) return [Eq(x(t), sol1), Eq(y(t), sol2)] def _linear_2eq_order2_type11(x, y, t, r, eq): r""" The equations which comes under this type are .. math:: x'' = f(t) (t x' - x) + g(t) (t y' - y) .. math:: y'' = h(t) (t x' - x) + p(t) (t y' - y) The transformation .. math:: u = t x' - x, v = t y' - y leads to the linear system of first-order equations .. math:: u' = t f(t) u + t g(t) v, v' = t h(t) u + t p(t) v On substituting the value of `u` and `v` in transformed equation gives value of `x` and `y` as .. math:: x = C_3 t + t \int \frac{u}{t^2} \,dt , y = C_4 t + t \int \frac{v}{t^2} \,dt. where `C_3` and `C_4` are arbitrary constants. """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) u, v = symbols('u, v', cls=Function) f = -r['c1'] ; g = -r['d1'] h = -r['c2'] ; p = -r['d2'] [msol1, msol2] = dsolve([Eq(diff(u(t),t), tfu(t) + tgv(t)), Eq(diff(v(t),t), thu(t) + tpv(t))]) sol1 = C3t + tIntegral(msol1.rhs/t*2, t) sol2 = C4t + tIntegral(msol2.rhs/t2, t) return [Eq(x(t), sol1), Eq(y(t), sol2)] def sysode_linear_3eq_order1(match_): x = match_['func'][0].func y = match_['func'][1].func z = match_['func'][2].func func = match_['func'] fc = match_['func_coeff'] eq = match_['eq'] C1, C2, C3, C4 = get_numbered_constants(eq, num=4) r = dict() t = list(list(eq[0].atoms(Derivative))[0].atoms(Symbol))[0] for i in range(3): eqs = 0 for terms in Add.make_args(eq[i]): eqs += terms/fc[i,func[i],1] eq[i] = eqs # for equations: # Eq(g1diff(x(t),t), a1x(t)+b1y(t)+c1z(t)+d1), # Eq(g2diff(y(t),t), a2x(t)+b2y(t)+c2z(t)+d2), and # Eq(g3diff(z(t),t), a3x(t)+b3y(t)+c3z(t)+d3) r['a1'] = fc[0,x(t),0]/fc[0,x(t),1]; r['a2'] = fc[1,x(t),0]/fc[1,y(t),1]; r['a3'] = fc[2,x(t),0]/fc[2,z(t),1] r['b1'] = fc[0,y(t),0]/fc[0,x(t),1]; r['b2'] = fc[1,y(t),0]/fc[1,y(t),1]; r['b3'] = fc[2,y(t),0]/fc[2,z(t),1] r['c1'] = fc[0,z(t),0]/fc[0,x(t),1]; r['c2'] = fc[1,z(t),0]/fc[1,y(t),1]; r['c3'] = fc[2,z(t),0]/fc[2,z(t),1] for i in range(3): for j in Add.make_args(eq[i]): if not j.has(x(t), y(t), z(t)): raise NotImplementedError("Only homogeneous problems are supported, non-homogenous are not supported currently.") if match_['type_of_equation'] == 'type1': sol = _linear_3eq_order1_type1(x, y, z, t, r, eq) if match_['type_of_equation'] == 'type2': sol = _linear_3eq_order1_type2(x, y, z, t, r, eq) if match_['type_of_equation'] == 'type3': sol = _linear_3eq_order1_type3(x, y, z, t, r, eq) if match_['type_of_equation'] == 'type4': sol = _linear_3eq_order1_type4(x, y, z, t, r, eq) if match_['type_of_equation'] == 'type6': sol = _linear_neq_order1_type1(match_) return sol def _linear_3eq_order1_type1(x, y, z, t, r, eq): r""" .. math:: x' = ax .. math:: y' = bx + cy .. math:: z' = dx + ky + pz Solution of such equations are forward substitution. Solving first equations gives the value of `x`, substituting it in second and third equation and solving second equation gives `y` and similarly substituting `y` in third equation give `z`. .. math:: x = C_1 e^{at} .. math:: y = \frac{b C_1}{a - c} e^{at} + C_2 e^{ct} .. math:: z = \frac{C_1}{a - p} (d + \frac{bk}{a - c}) e^{at} + \frac{k C_2}{c - p} e^{ct} + C_3 e^{pt} where `C_1, C_2` and `C_3` are arbitrary constants. """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) a = -r['a1']; b = -r['a2']; c = -r['b2'] d = -r['a3']; k = -r['b3']; p = -r['c3'] sol1 = C1exp(at) sol2 = bC1exp(at)/(a-c) + C2exp(ct) sol3 = C1(d+bk/(a-c))exp(at)/(a-p) + kC2exp(ct)/(c-p) + C3exp(pt) return [Eq(x(t), sol1), Eq(y(t), sol2), Eq(z(t), sol3)] def _linear_3eq_order1_type2(x, y, z, t, r, eq): r""" The equations of this type are .. math:: x' = cy - bz .. math:: y' = az - cx .. math:: z' = bx - ay 1. First integral: .. math:: ax + by + cz = A \qquad - (1) .. math:: x^2 + y^2 + z^2 = B^2 \qquad - (2) where `A` and `B` are arbitrary constants. It follows from these integrals that the integral lines are circles formed by the intersection of the planes `(1)` and sphere `(2)` 2. Solution: .. math:: x = a C_0 + k C_1 \cos(kt) + (c C_2 - b C_3) \sin(kt) .. math:: y = b C_0 + k C_2 \cos(kt) + (a C_2 - c C_3) \sin(kt) .. math:: z = c C_0 + k C_3 \cos(kt) + (b C_2 - a C_3) \sin(kt) where `k = \sqrt{a^2 + b^2 + c^2}` and the four constants of integration, `C_1,...,C_4` are constrained by a single relation, .. math:: a C_1 + b C_2 + c C_3 = 0 """ C0, C1, C2, C3 = get_numbered_constants(eq, num=4, start=0) a = -r['c2']; b = -r['a3']; c = -r['b1'] k = sqrt(a2 + b2 + c2) C3 = (-aC1 - bC2)/c sol1 = aC0 + kC1cos(kt) + (cC2-bC3)sin(kt) sol2 = bC0 + kC2cos(kt) + (aC3-cC1)sin(kt) sol3 = cC0 + kC3cos(kt) + (bC1-aC2)sin(kt) return [Eq(x(t), sol1), Eq(y(t), sol2), Eq(z(t), sol3)] def _linear_3eq_order1_type3(x, y, z, t, r, eq): r""" Equations of this system of ODEs .. math:: a x' = bc (y - z) .. math:: b y' = ac (z - x) .. math:: c z' = ab (x - y) 1. First integral: .. math:: a^2 x + b^2 y + c^2 z = A where A is an arbitrary constant. It follows that the integral lines are plane curves. 2. Solution: .. math:: x = C_0 + k C_1 \cos(kt) + a^{-1} bc (C_2 - C_3) \sin(kt) .. math:: y = C_0 + k C_2 \cos(kt) + a b^{-1} c (C_3 - C_1) \sin(kt) .. math:: z = C_0 + k C_3 \cos(kt) + ab c^{-1} (C_1 - C_2) \sin(kt) where `k = \sqrt{a^2 + b^2 + c^2}` and the four constants of integration, `C_1,...,C_4` are constrained by a single relation .. math:: a^2 C_1 + b^2 C_2 + c^2 C_3 = 0 """ C0, C1, C2, C3 = get_numbered_constants(eq, num=4, start=0) c = sqrt(r['b1']r['c2']) b = sqrt(r['b1']r['a3']) a = sqrt(r['c2']r['a3']) C3 = (-a*2C1-b*2C2)/c2 k = sqrt(a2 + b2 + c2) sol1 = C0 + kC1cos(kt) + a-1bc(C2-C3)sin(kt) sol2 = C0 + kC2cos(kt) + ab*-1c(C3-C1)sin(kt) sol3 = C0 + kC3cos(kt) + abc*-1(C1-C2)sin(kt) return [Eq(x(t), sol1), Eq(y(t), sol2), Eq(z(t), sol3)] def _linear_3eq_order1_type4(x, y, z, t, r, eq): r""" Equations: .. math:: x' = (a_1 f(t) + g(t)) x + a_2 f(t) y + a_3 f(t) z .. math:: y' = b_1 f(t) x + (b_2 f(t) + g(t)) y + b_3 f(t) z .. math:: z' = c_1 f(t) x + c_2 f(t) y + (c_3 f(t) + g(t)) z The transformation .. math:: x = e^{\int g(t) \,dt} u, y = e^{\int g(t) \,dt} v, z = e^{\int g(t) \,dt} w, \tau = \int f(t) \,dt leads to the system of constant coefficient linear differential equations .. math:: u' = a_1 u + a_2 v + a_3 w .. math:: v' = b_1 u + b_2 v + b_3 w .. math:: w' = c_1 u + c_2 v + c_3 w These system of equations are solved by homogeneous linear system of constant coefficients of `n` equations of first order. Then substituting the value of `u, v` and `w` in transformed equation gives value of `x, y` and `z`. """ u, v, w = symbols('u, v, w', cls=Function) a2, a3 = cancel(r['b1']/r['c1']).as_numer_denom() f = cancel(r['b1']/a2) b1 = cancel(r['a2']/f); b3 = cancel(r['c2']/f) c1 = cancel(r['a3']/f); c2 = cancel(r['b3']/f) a1, g = div(r['a1'],f) b2 = div(r['b2'],f)[0] c3 = div(r['c3'],f)[0] trans_eq = (diff(u(t),t)-a1u(t)-a2v(t)-a3w(t), diff(v(t),t)-b1u(t)-\ b2v(t)-b3w(t), diff(w(t),t)-c1u(t)-c2v(t)-c3w(t)) sol = dsolve(trans_eq) sol1 = exp(Integral(g,t))((sol[0].rhs).subs(t, Integral(f,t))) sol2 = exp(Integral(g,t))((sol[1].rhs).subs(t, Integral(f,t))) sol3 = exp(Integral(g,t))((sol[2].rhs).subs(t, Integral(f,t))) return [Eq(x(t), sol1), Eq(y(t), sol2), Eq(z(t), sol3)] def sysode_linear_neq_order1(match_): sol = _linear_neq_order1_type1(match_) return sol def _linear_neq_order1_type1(match_): r""" System of n first-order constant-coefficient linear nonhomogeneous differential equation .. math:: y'_k = a_{k1} y_1 + a_{k2} y_2 +...+ a_{kn} y_n; k = 1,2,...,n or that can be written as `\vec{y'} = A . \vec{y}` where `\vec{y}` is matrix of `y_k` for `k = 1,2,...n` and `A` is a `n \times n` matrix. Since these equations are equivalent to a first order homogeneous linear differential equation. So the general solution will contain `n` linearly independent parts and solution will consist some type of exponential functions. Assuming `y = \vec{v} e^{rt}` is a solution of the system where `\vec{v}` is a vector of coefficients of `y_1,...,y_n`. Substituting `y` and `y' = r v e^{r t}` into the equation `\vec{y'} = A . \vec{y}`, we get .. math:: r \vec{v} e^{rt} = A \vec{v} e^{rt} .. math:: r \vec{v} = A \vec{v} where `r` comes out to be eigenvalue of `A` and vector `\vec{v}` is the eigenvector of `A` corresponding to `r`. There are three possibilities of eigenvalues of `A` - `n` distinct real eigenvalues - complex conjugate eigenvalues - eigenvalues with multiplicity `k` 1. When all eigenvalues `r_1,..,r_n` are distinct with `n` different eigenvectors `v_1,...v_n` then the solution is given by .. math:: \vec{y} = C_1 e^{r_1 t} \vec{v_1} + C_2 e^{r_2 t} \vec{v_2} +...+ C_n e^{r_n t} \vec{v_n} where `C_1,C_2,...,C_n` are arbitrary constants. 2. When some eigenvalues are complex then in order to make the solution real, we take a linear combination: if `r = a + bi` has an eigenvector `\vec{v} = \vec{w_1} + i \vec{w_2}` then to obtain real-valued solutions to the system, replace the complex-valued solutions `e^{rx} \vec{v}` with real-valued solution `e^{ax} (\vec{w_1} \cos(bx) - \vec{w_2} \sin(bx))` and for `r = a - bi` replace the solution `e^{-r x} \vec{v}` with `e^{ax} (\vec{w_1} \sin(bx) + \vec{w_2} \cos(bx))` 3. If some eigenvalues are repeated. Then we get fewer than `n` linearly independent eigenvectors, we miss some of the solutions and need to construct the missing ones. We do this via generalized eigenvectors, vectors which are not eigenvectors but are close enough that we can use to write down the remaining solutions. For a eigenvalue `r` with eigenvector `\vec{w}` we obtain `\vec{w_2},...,\vec{w_k}` using .. math:: (A - r I) . \vec{w_2} = \vec{w} .. math:: (A - r I) . \vec{w_3} = \vec{w_2} .. math:: \vdots .. math:: (A - r I) . \vec{w_k} = \vec{w_{k-1}} Then the solutions to the system for the eigenspace are `e^{rt} [\vec{w}], e^{rt} [t \vec{w} + \vec{w_2}], e^{rt} [\frac{t^2}{2} \vec{w} + t \vec{w_2} + \vec{w_3}], ...,e^{rt} [\frac{t^{k-1}}{(k-1)!} \vec{w} + \frac{t^{k-2}}{(k-2)!} \vec{w_2} +...+ t \vec{w_{k-1}} + \vec{w_k}]` So, If `\vec{y_1},...,\vec{y_n}` are `n` solution of obtained from three categories of `A`, then general solution to the system `\vec{y'} = A . \vec{y}` .. math:: \vec{y} = C_1 \vec{y_1} + C_2 \vec{y_2} + \cdots + C_n \vec{y_n} """ eq = match_['eq'] func = match_['func'] fc = match_['func_coeff'] n = len(eq) t = list(list(eq[0].atoms(Derivative))[0].atoms(Symbol))[0] constants = numbered_symbols(prefix='C', cls=Symbol, start=1) M = Matrix(n,n,lambda i,j:-fc[i,func[j],0]) evector = M.eigenvects(simplify=True) def is_complex(mat, root): return Matrix(n, 1, lambda i,j: re(mat[i])cos(im(root)t) - im(mat[i])sin(im(root)t)) def is_complex_conjugate(mat, root): return Matrix(n, 1, lambda i,j: re(mat[i])sin(abs(im(root))t) + im(mat[i])cos(im(root)t)abs(im(root))/im(root)) conjugate_root = [] e_vector = zeros(n,1) for evects in evector: if evects[0] not in conjugate_root: # If number of column of an eigenvector is not equal to the multiplicity # of its eigenvalue then the legt eigenvectors are calculated if len(evects[2])!=evects[1]: var_mat = Matrix(n, 1, lambda i,j: Symbol('x'+str(i))) Mnew = (M - evects[0]eye(evects[2][-1].rows))var_mat w = [0 for i in range(evects[1])] w[0] = evects[2][-1] for r in range(1, evects[1]): w_ = Mnew - w[r-1] sol_dict = solve(list(w_), var_mat[1:]) sol_dict[var_mat[0]] = var_mat[0] for key, value in sol_dict.items(): sol_dict[key] = value.subs(var_mat[0],1) w[r] = Matrix(n, 1, lambda i,j: sol_dict[var_mat[i]]) evects[2].append(w[r]) for i in range(evects[1]): C = next(constants) for j in range(i+1): if evects[0].has(I): evects[2][j] = simplify(evects[2][j]) e_vector += Cis_complex(evects[2][j], evects[0])t(i-j)exp(re(evects[0])t)/factorial(i-j) C = next(constants) e_vector += Cis_complex_conjugate(evects[2][j], evects[0])t(i-j)exp(re(evects[0])t)/factorial(i-j) else: e_vector += Cevects[2][j]t(i-j)exp(evects[0]t)/factorial(i-j) if evects[0].has(I): conjugate_root.append(conjugate(evects[0])) sol = [] for i in range(len(eq)): sol.append(Eq(func[i],e_vector[i])) return sol def sysode_nonlinear_2eq_order1(match_): func = match_['func'] eq = match_['eq'] fc = match_['func_coeff'] t = list(list(eq[0].atoms(Derivative))[0].atoms(Symbol))[0] if match_['type_of_equation'] == 'type5': sol = _nonlinear_2eq_order1_type5(func, t, eq) return sol x = func[0].func y = func[1].func for i in range(2): eqs = 0 for terms in Add.make_args(eq[i]): eqs += terms/fc[i,func[i],1] eq[i] = eqs if match_['type_of_equation'] == 'type1': sol = _nonlinear_2eq_order1_type1(x, y, t, eq) elif match_['type_of_equation'] == 'type2': sol = _nonlinear_2eq_order1_type2(x, y, t, eq) elif match_['type_of_equation'] == 'type3': sol = _nonlinear_2eq_order1_type3(x, y, t, eq) elif match_['type_of_equation'] == 'type4': sol = _nonlinear_2eq_order1_type4(x, y, t, eq) return sol def _nonlinear_2eq_order1_type1(x, y, t, eq): r""" Equations: .. math:: x' = x^n F(x,y) .. math:: y' = g(y) F(x,y) Solution: .. math:: x = \varphi(y), \int \frac{1}{g(y) F(\varphi(y),y)} \,dy = t + C_2 where if `n \neq 1` .. math:: \varphi = [C_1 + (1-n) \int \frac{1}{g(y)} \,dy]^{\frac{1}{1-n}} if `n = 1` .. math:: \varphi = C_1 e^{\int \frac{1}{g(y)} \,dy} where `C_1` and `C_2` are arbitrary constants. """ C1, C2 = get_numbered_constants(eq, num=2) n = Wild('n', exclude=[x(t),y(t)]) f = Wild('f') u, v = symbols('u, v') r = eq[0].match(diff(x(t),t) - x(t)nf) g = ((diff(y(t),t) - eq[1])/r[f]).subs(y(t),v) F = r[f].subs(x(t),u).subs(y(t),v) n = r[n] if n!=1: phi = (C1 + (1-n)Integral(1/g, v))(1/(1-n)) else: phi = C1exp(Integral(1/g, v)) phi = phi.doit() sol2 = solve(Integral(1/(gF.subs(u,phi)), v).doit() - t - C2, v) sol = [] for sols in sol2: sol.append(Eq(x(t),phi.subs(v, sols))) sol.append(Eq(y(t), sols)) return sol def _nonlinear_2eq_order1_type2(x, y, t, eq): r""" Equations: .. math:: x' = e^{\lambda x} F(x,y) .. math:: y' = g(y) F(x,y) Solution: .. math:: x = \varphi(y), \int \frac{1}{g(y) F(\varphi(y),y)} \,dy = t + C_2 where if `\lambda \neq 0` .. math:: \varphi = -\frac{1}{\lambda} log(C_1 - \lambda \int \frac{1}{g(y)} \,dy) if `\lambda = 0` .. math:: \varphi = C_1 + \int \frac{1}{g(y)} \,dy where `C_1` and `C_2` are arbitrary constants. """ C1, C2 = get_numbered_constants(eq, num=2) n = Wild('n', exclude=[x(t),y(t)]) f = Wild('f') u, v = symbols('u, v') r = eq[0].match(diff(x(t),t) - exp(nx(t))f) g = ((diff(y(t),t) - eq[1])/r[f]).subs(y(t),v) F = r[f].subs(x(t),u).subs(y(t),v) n = r[n] if n: phi = -1/nlog(C1 - nIntegral(1/g, v)) else: phi = C1 + Integral(1/g, v) phi = phi.doit() sol2 = solve(Integral(1/(gF.subs(u,phi)), v).doit() - t - C2, v) sol = [] for sols in sol2: sol.append(Eq(x(t),phi.subs(v, sols))) sol.append(Eq(y(t), sols)) return sol def _nonlinear_2eq_order1_type3(x, y, t, eq): r""" Autonomous system of general form .. math:: x' = F(x,y) .. math:: y' = G(x,y) Assuming `y = y(x, C_1)` where `C_1` is an arbitrary constant is the general solution of the first-order equation .. math:: F(x,y) y'_x = G(x,y) Then the general solution of the original system of equations has the form .. math:: \int \frac{1}{F(x,y(x,C_1))} \,dx = t + C_1 """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) v = Function('v') u = Symbol('u') f = Wild('f') g = Wild('g') r1 = eq[0].match(diff(x(t),t) - f) r2 = eq[1].match(diff(y(t),t) - g) F = r1[f].subs(x(t), u).subs(y(t), v(u)) G = r2[g].subs(x(t), u).subs(y(t), v(u)) sol2r = dsolve(Eq(diff(v(u), u), G/F)) for sol2s in sol2r: sol1 = solve(Integral(1/F.subs(v(u), sol2s.rhs), u).doit() - t - C2, u) sol = [] for sols in sol1: sol.append(Eq(x(t), sols)) sol.append(Eq(y(t), (sol2s.rhs).subs(u, sols))) return sol def _nonlinear_2eq_order1_type4(x, y, t, eq): r""" Equation: .. math:: x' = f_1(x) g_1(y) \phi(x,y,t) .. math:: y' = f_2(x) g_2(y) \phi(x,y,t) First integral: .. math:: \int \frac{f_2(x)}{f_1(x)} \,dx - \int \frac{g_1(y)}{g_2(y)} \,dy = C where `C` is an arbitrary constant. On solving the first integral for `x` (resp., `y` ) and on substituting the resulting expression into either equation of the original solution, one arrives at a first-order equation for determining `y` (resp., `x` ). """ C1, C2 = get_numbered_constants(eq, num=2) u, v = symbols('u, v') U, V = symbols('U, V', cls=Function) f = Wild('f') g = Wild('g') f1 = Wild('f1', exclude=[v,t]) f2 = Wild('f2', exclude=[v,t]) g1 = Wild('g1', exclude=[u,t]) g2 = Wild('g2', exclude=[u,t]) r1 = eq[0].match(diff(x(t),t) - f) r2 = eq[1].match(diff(y(t),t) - g) num, den = ( (r1[f].subs(x(t),u).subs(y(t),v))/ (r2[g].subs(x(t),u).subs(y(t),v))).as_numer_denom() R1 = num.match(f1g1) R2 = den.match(f2g2) phi = (r1[f].subs(x(t),u).subs(y(t),v))/num F1 = R1[f1]; F2 = R2[f2] G1 = R1[g1]; G2 = R2[g2] sol1r = solve(Integral(F2/F1, u).doit() - Integral(G1/G2,v).doit() - C1, u) sol2r = solve(Integral(F2/F1, u).doit() - Integral(G1/G2,v).doit() - C1, v) sol = [] for sols in sol1r: sol.append(Eq(y(t), dsolve(diff(V(t),t) - F2.subs(u,sols).subs(v,V(t))G2.subs(v,V(t))phi.subs(u,sols).subs(v,V(t))).rhs)) for sols in sol2r: sol.append(Eq(x(t), dsolve(diff(U(t),t) - F1.subs(u,U(t))G1.subs(v,sols).subs(u,U(t))phi.subs(v,sols).subs(u,U(t))).rhs)) return set(sol) def _nonlinear_2eq_order1_type5(func, t, eq): r""" Clairaut system of ODEs .. math:: x = t x' + F(x',y') .. math:: y = t y' + G(x',y') The following are solutions of the system `(i)` straight lines: .. math:: x = C_1 t + F(C_1, C_2), y = C_2 t + G(C_1, C_2) where `C_1` and `C_2` are arbitrary constants; `(ii)` envelopes of the above lines; `(iii)` continuously differentiable lines made up from segments of the lines `(i)` and `(ii)`. """ C1, C2 = get_numbered_constants(eq, num=2) f = Wild('f') g = Wild('g') def check_type(x, y): r1 = eq[0].match(tdiff(x(t),t) - x(t) + f) r2 = eq[1].match(tdiff(y(t),t) - y(t) + g) if not (r1 and r2): r1 = eq[0].match(diff(x(t),t) - x(t)/t + f/t) r2 = eq[1].match(diff(y(t),t) - y(t)/t + g/t) if not (r1 and r2): r1 = (-eq[0]).match(tdiff(x(t),t) - x(t) + f) r2 = (-eq[1]).match(tdiff(y(t),t) - y(t) + g) if not (r1 and r2): r1 = (-eq[0]).match(diff(x(t),t) - x(t)/t + f/t) r2 = (-eq[1]).match(diff(y(t),t) - y(t)/t + g/t) return [r1, r2] for func_ in func: if isinstance(func_, list): x = func[0][0].func y = func[0][1].func [r1, r2] = check_type(x, y) if not (r1 and r2): [r1, r2] = check_type(y, x) x, y = y, x x1 = diff(x(t),t); y1 = diff(y(t),t) return {Eq(x(t), C1t + r1[f].subs(x1,C1).subs(y1,C2)), Eq(y(t), C2t + r2[g].subs(x1,C1).subs(y1,C2))} def sysode_nonlinear_3eq_order1(match_): x = match_['func'][0].func y = match_['func'][1].func z = match_['func'][2].func eq = match_['eq'] fc = match_['func_coeff'] func = match_['func'] t = list(list(eq[0].atoms(Derivative))[0].atoms(Symbol))[0] if match_['type_of_equation'] == 'type1': sol = _nonlinear_3eq_order1_type1(x, y, z, t, eq) if match_['type_of_equation'] == 'type2': sol = _nonlinear_3eq_order1_type2(x, y, z, t, eq) if match_['type_of_equation'] == 'type3': sol = _nonlinear_3eq_order1_type3(x, y, z, t, eq) if match_['type_of_equation'] == 'type4': sol = _nonlinear_3eq_order1_type4(x, y, z, t, eq) if match_['type_of_equation'] == 'type5': sol = _nonlinear_3eq_order1_type5(x, y, z, t, eq) return sol def _nonlinear_3eq_order1_type1(x, y, z, t, eq): r""" Equations: .. math:: a x' = (b - c) y z, \enspace b y' = (c - a) z x, \enspace c z' = (a - b) x y First Integrals: .. math:: a x^{2} + b y^{2} + c z^{2} = C_1 .. math:: a^{2} x^{2} + b^{2} y^{2} + c^{2} z^{2} = C_2 where `C_1` and `C_2` are arbitrary constants. On solving the integrals for `y` and `z` and on substituting the resulting expressions into the first equation of the system, we arrives at a separable first-order equation on `x`. Similarly doing that for other two equations, we will arrive at first order equation on `y` and `z` too. References ========== -http://eqworld.ipmnet.ru/en/solutions/sysode/sode0401.pdf """ C1, C2 = get_numbered_constants(eq, num=2) u, v, w = symbols('u, v, w') p = Wild('p', exclude=[x(t), y(t), z(t), t]) q = Wild('q', exclude=[x(t), y(t), z(t), t]) s = Wild('s', exclude=[x(t), y(t), z(t), t]) r = (diff(x(t),t) - eq[0]).match(py(t)z(t)) r.update((diff(y(t),t) - eq[1]).match(qz(t)x(t))) r.update((diff(z(t),t) - eq[2]).match(sx(t)y(t))) n1, d1 = r[p].as_numer_denom() n2, d2 = r[q].as_numer_denom() n3, d3 = r[s].as_numer_denom() val = solve([n1u-d1v+d1w, d2u+n2v-d2w, d3u-d3v-n3w],[u,v]) vals = [val[v], val[u]] c = lcm(vals[0].as_numer_denom()[1], vals[1].as_numer_denom()[1]) b = vals[0].subs(w,c) a = vals[1].subs(w,c) y_x = sqrt(((cC1-C2) - a(c-a)x(t)*2)/(b(c-b))) z_x = sqrt(((bC1-C2) - a(b-a)x(t)2)/(c(b-c))) z_y = sqrt(((aC1-C2) - b(a-b)y(t)2)/(c(a-c))) x_y = sqrt(((cC1-C2) - b(c-b)y(t)2)/(a(c-a))) x_z = sqrt(((bC1-C2) - c(b-c)z(t)2)/(a(b-a))) y_z = sqrt(((aC1-C2) - c(a-c)z(t)2)/(b(a-b))) sol1 = dsolve(adiff(x(t),t) - (b-c)y_xz_x) sol2 = dsolve(bdiff(y(t),t) - (c-a)z_yx_y) sol3 = dsolve(cdiff(z(t),t) - (a-b)x_zy_z) return [sol1, sol2, sol3] def _nonlinear_3eq_order1_type2(x, y, z, t, eq): r""" Equations: .. math:: a x' = (b - c) y z f(x, y, z, t) .. math:: b y' = (c - a) z x f(x, y, z, t) .. math:: c z' = (a - b) x y f(x, y, z, t) First Integrals: .. math:: a x^{2} + b y^{2} + c z^{2} = C_1 .. math:: a^{2} x^{2} + b^{2} y^{2} + c^{2} z^{2} = C_2 where `C_1` and `C_2` are arbitrary constants. On solving the integrals for `y` and `z` and on substituting the resulting expressions into the first equation of the system, we arrives at a first-order differential equations on `x`. Similarly doing that for other two equations we will arrive at first order equation on `y` and `z`. References ========== -http://eqworld.ipmnet.ru/en/solutions/sysode/sode0402.pdf """ C1, C2 = get_numbered_constants(eq, num=2) u, v, w = symbols('u, v, w') p = Wild('p', exclude=[x(t), y(t), z(t), t]) q = Wild('q', exclude=[x(t), y(t), z(t), t]) s = Wild('s', exclude=[x(t), y(t), z(t), t]) f = Wild('f') r1 = (diff(x(t),t) - eq[0]).match(y(t)z(t)f) r = collect_const(r1[f]).match(pf) r.update(((diff(y(t),t) - eq[1])/r[f]).match(qz(t)x(t))) r.update(((diff(z(t),t) - eq[2])/r[f]).match(sx(t)y(t))) n1, d1 = r[p].as_numer_denom() n2, d2 = r[q].as_numer_denom() n3, d3 = r[s].as_numer_denom() val = solve([n1u-d1v+d1w, d2u+n2v-d2w, -d3u+d3v+n3w],[u,v]) vals = [val[v], val[u]] c = lcm(vals[0].as_numer_denom()[1], vals[1].as_numer_denom()[1]) a = vals[0].subs(w,c) b = vals[1].subs(w,c) y_x = sqrt(((cC1-C2) - a(c-a)x(t)*2)/(b(c-b))) z_x = sqrt(((bC1-C2) - a(b-a)x(t)2)/(c(b-c))) z_y = sqrt(((aC1-C2) - b(a-b)y(t)2)/(c(a-c))) x_y = sqrt(((cC1-C2) - b(c-b)y(t)2)/(a(c-a))) x_z = sqrt(((bC1-C2) - c(b-c)z(t)2)/(a(b-a))) y_z = sqrt(((aC1-C2) - c(a-c)z(t)2)/(b(a-b))) sol1 = dsolve(adiff(x(t),t) - (b-c)y_xz_xr[f]) sol2 = dsolve(bdiff(y(t),t) - (c-a)z_yx_yr[f]) sol3 = dsolve(cdiff(z(t),t) - (a-b)x_zy_zr[f]) return [sol1, sol2, sol3] def _nonlinear_3eq_order1_type3(x, y, z, t, eq): r""" Equations: .. math:: x' = c F_2 - b F_3, \enspace y' = a F_3 - c F_1, \enspace z' = b F_1 - a F_2 where `F_n = F_n(x, y, z, t)`. 1. First Integral: .. math:: a x + b y + c z = C_1, where C is an arbitrary constant. 2. If we assume function `F_n` to be independent of `t`,i.e, `F_n` = `F_n (x, y, z)` Then, on eliminating `t` and `z` from the first two equation of the system, one arrives at the first-order equation .. math:: \frac{dy}{dx} = \frac{a F_3 (x, y, z) - c F_1 (x, y, z)}{c F_2 (x, y, z) - b F_3 (x, y, z)} where `z = \frac{1}{c} (C_1 - a x - b y)` References ========== -http://eqworld.ipmnet.ru/en/solutions/sysode/sode0404.pdf """ C1 = get_numbered_constants(eq, num=1) u, v, w = symbols('u, v, w') p = Wild('p', exclude=[x(t), y(t), z(t), t]) q = Wild('q', exclude=[x(t), y(t), z(t), t]) s = Wild('s', exclude=[x(t), y(t), z(t), t]) F1, F2, F3 = symbols('F1, F2, F3', cls=Wild) r1 = (diff(x(t),t) - eq[0]).match(F2-F3) r = collect_const(r1[F2]).match(sF2) r.update(collect_const(r1[F3]).match(qF3)) if eq[1].has(r[F2]) and not eq[1].has(r[F3]): r[F2], r[F3] = r[F3], r[F2] r[s], r[q] = -r[q], -r[s] r.update((diff(y(t),t) - eq[1]).match(pr[F3] - r[s]F1)) a = r[p]; b = r[q]; c = r[s] F1 = r[F1].subs(x(t),u).subs(y(t),v).subs(z(t),w) F2 = r[F2].subs(x(t),u).subs(y(t),v).subs(z(t),w) F3 = r[F3].subs(x(t),u).subs(y(t),v).subs(z(t),w) z_xy = (C1-au-bv)/c y_zx = (C1-au-cw)/b x_yz = (C1-bv-cw)/a y_x = dsolve(diff(v(u),u) - ((aF3-cF1)/(cF2-bF3)).subs(w,z_xy).subs(v,v(u))).rhs z_x = dsolve(diff(w(u),u) - ((bF1-aF2)/(cF2-bF3)).subs(v,y_zx).subs(w,w(u))).rhs z_y = dsolve(diff(w(v),v) - ((bF1-aF2)/(aF3-cF1)).subs(u,x_yz).subs(w,w(v))).rhs x_y = dsolve(diff(u(v),v) - ((cF2-bF3)/(aF3-cF1)).subs(w,z_xy).subs(u,u(v))).rhs y_z = dsolve(diff(v(w),w) - ((aF3-cF1)/(bF1-aF2)).subs(u,x_yz).subs(v,v(w))).rhs x_z = dsolve(diff(u(w),w) - ((cF2-bF3)/(bF1-aF2)).subs(v,y_zx).subs(u,u(w))).rhs sol1 = dsolve(diff(u(t),t) - (cF2 - bF3).subs(v,y_x).subs(w,z_x).subs(u,u(t))).rhs sol2 = dsolve(diff(v(t),t) - (aF3 - cF1).subs(u,x_y).subs(w,z_y).subs(v,v(t))).rhs sol3 = dsolve(diff(w(t),t) - (bF1 - aF2).subs(u,x_z).subs(v,y_z).subs(w,w(t))).rhs return [sol1, sol2, sol3] def _nonlinear_3eq_order1_type4(x, y, z, t, eq): r""" Equations: .. math:: x' = c z F_2 - b y F_3, \enspace y' = a x F_3 - c z F_1, \enspace z' = b y F_1 - a x F_2 where `F_n = F_n (x, y, z, t)` 1. First integral: .. math:: a x^{2} + b y^{2} + c z^{2} = C_1 where `C` is an arbitrary constant. 2. Assuming the function `F_n` is independent of `t`: `F_n = F_n (x, y, z)`. Then on eliminating `t` and `z` from the first two equations of the system, one arrives at the first-order equation .. math:: \frac{dy}{dx} = \frac{a x F_3 (x, y, z) - c z F_1 (x, y, z)} {c z F_2 (x, y, z) - b y F_3 (x, y, z)} where `z = \pm \sqrt{\frac{1}{c} (C_1 - a x^{2} - b y^{2})}` References ========== -http://eqworld.ipmnet.ru/en/solutions/sysode/sode0405.pdf """ C1 = get_numbered_constants(eq, num=1) u, v, w = symbols('u, v, w') p = Wild('p', exclude=[x(t), y(t), z(t), t]) q = Wild('q', exclude=[x(t), y(t), z(t), t]) s = Wild('s', exclude=[x(t), y(t), z(t), t]) F1, F2, F3 = symbols('F1, F2, F3', cls=Wild) r1 = eq[0].match(diff(x(t),t) - z(t)F2 + y(t)F3) r = collect_const(r1[F2]).match(sF2) r.update(collect_const(r1[F3]).match(qF3)) if eq[1].has(r[F2]) and not eq[1].has(r[F3]): r[F2], r[F3] = r[F3], r[F2] r[s], r[q] = -r[q], -r[s] r.update((diff(y(t),t) - eq[1]).match(px(t)r[F3] - r[s]z(t)F1)) a = r[p]; b = r[q]; c = r[s] F1 = r[F1].subs(x(t),u).subs(y(t),v).subs(z(t),w) F2 = r[F2].subs(x(t),u).subs(y(t),v).subs(z(t),w) F3 = r[F3].subs(x(t),u).subs(y(t),v).subs(z(t),w) x_yz = sqrt((C1 - bv2 - cw*2)/a) y_zx = sqrt((C1 - cw*2 - au*2)/b) z_xy = sqrt((C1 - au*2 - bv*2)/c) y_x = dsolve(diff(v(u),u) - ((auF3-cwF1)/(cwF2-bvF3)).subs(w,z_xy).subs(v,v(u))).rhs z_x = dsolve(diff(w(u),u) - ((bvF1-auF2)/(cwF2-bvF3)).subs(v,y_zx).subs(w,w(u))).rhs z_y = dsolve(diff(w(v),v) - ((bvF1-auF2)/(auF3-cwF1)).subs(u,x_yz).subs(w,w(v))).rhs x_y = dsolve(diff(u(v),v) - ((cwF2-bvF3)/(auF3-cwF1)).subs(w,z_xy).subs(u,u(v))).rhs y_z = dsolve(diff(v(w),w) - ((auF3-cwF1)/(bvF1-auF2)).subs(u,x_yz).subs(v,v(w))).rhs x_z = dsolve(diff(u(w),w) - ((cwF2-bvF3)/(bvF1-auF2)).subs(v,y_zx).subs(u,u(w))).rhs sol1 = dsolve(diff(u(t),t) - (cwF2 - bvF3).subs(v,y_x).subs(w,z_x).subs(u,u(t))).rhs sol2 = dsolve(diff(v(t),t) - (auF3 - cwF1).subs(u,x_y).subs(w,z_y).subs(v,v(t))).rhs sol3 = dsolve(diff(w(t),t) - (bvF1 - auF2).subs(u,x_z).subs(v,y_z).subs(w,w(t))).rhs return [sol1, sol2, sol3] def _nonlinear_3eq_order1_type5(x, y, t, eq): r""" .. math:: x' = x (c F_2 - b F_3), \enspace y' = y (a F_3 - c F_1), \enspace z' = z (b F_1 - a F_2) where `F_n = F_n (x, y, z, t)` and are arbitrary functions. First Integral: .. math:: \left\|x\right\|^{a} \left\|y\right\|^{b} \left\|z\right\|^{c} = C_1 where `C` is an arbitrary constant. If the function `F_n` is independent of `t`, then, by eliminating `t` and `z` from the first two equations of the system, one arrives at a first-order equation. References ========== -http://eqworld.ipmnet.ru/en/solutions/sysode/sode0406.pdf """ C1 = get_numbered_constants(eq, num=1) u, v, w = symbols('u, v, w') p = Wild('p', exclude=[x(t), y(t), z(t), t]) q = Wild('q', exclude=[x(t), y(t), z(t), t]) s = Wild('s', exclude=[x(t), y(t), z(t), t]) F1, F2, F3 = symbols('F1, F2, F3', cls=Wild) r1 = eq[0].match(diff(x(t),t) - x(t)(F2 - F3)) r = collect_const(r1[F2]).match(sF2) r.update(collect_const(r1[F3]).match(qF3)) if eq[1].has(r[F2]) and not eq[1].has(r[F3]): r[F2], r[F3] = r[F3], r[F2] r[s], r[q] = -r[q], -r[s] r.update((diff(y(t),t) - eq[1]).match(y(t)(ar[F3] - r[c]F1))) a = r[p]; b = r[q]; c = r[s] F1 = r[F1].subs(x(t),u).subs(y(t),v).subs(z(t),w) F2 = r[F2].subs(x(t),u).subs(y(t),v).subs(z(t),w) F3 = r[F3].subs(x(t),u).subs(y(t),v).subs(z(t),w) x_yz = (C1v*-bw-c)-a y_zx = (C1w-cu-a)-b z_xy = (C1u-av-b)-c y_x = dsolve(diff(v(u),u) - ((v(aF3-cF1))/(u(cF2-bF3))).subs(w,z_xy).subs(v,v(u))).rhs z_x = dsolve(diff(w(u),u) - ((w(bF1-aF2))/(u(cF2-bF3))).subs(v,y_zx).subs(w,w(u))).rhs z_y = dsolve(diff(w(v),v) - ((w(bF1-aF2))/(v(aF3-cF1))).subs(u,x_yz).subs(w,w(v))).rhs x_y = dsolve(diff(u(v),v) - ((u(cF2-bF3))/(v(aF3-cF1))).subs(w,z_xy).subs(u,u(v))).rhs y_z = dsolve(diff(v(w),w) - ((v(aF3-cF1))/(w(bF1-aF2))).subs(u,x_yz).subs(v,v(w))).rhs x_z = dsolve(diff(u(w),w) - ((u(cF2-bF3))/(w(bF1-aF2))).subs(v,y_zx).subs(u,u(w))).rhs sol1 = dsolve(diff(u(t),t) - (u(cF2-bF3)).subs(v,y_x).subs(w,z_x).subs(u,u(t))).rhs sol2 = dsolve(diff(v(t),t) - (v(aF3-cF1)).subs(u,x_y).subs(w,z_y).subs(v,v(t))).rhs sol3 = dsolve(diff(w(t),t) - (w(bF1-a*F2)).subs(u,x_z).subs(v,y_z).subs(w,w(t))).rhs return [sol1, sol2, sol3]
8819bcbe4607ffb0a3a4249624f9bc218edabf7d94716c5c3280010e391374e4	from sympy import Order, S, log, limit, lcm_list, pi, Abs from sympy.core.basic import Basic from sympy.core import Add, Mul, Pow from sympy.logic.boolalg import And from sympy.core.expr import AtomicExpr, Expr from sympy.core.numbers import _sympifyit, oo from sympy.core.sympify import _sympify from sympy.sets.sets import (Interval, Intersection, FiniteSet, Union, Complement, EmptySet) from sympy.sets.conditionset import ConditionSet from sympy.functions.elementary.miscellaneous import Min, Max from sympy.utilities import filldedent from sympy.simplify.radsimp import denom from sympy.polys.rationaltools import together from sympy.core.compatibility import iterable def continuous_domain(f, symbol, domain): """ Returns the intervals in the given domain for which the function is continuous. This method is limited by the ability to determine the various singularities and discontinuities of the given function. Parameters ========== f : Expr The concerned function. symbol : Symbol The variable for which the intervals are to be determined. domain : Interval The domain over which the continuity of the symbol has to be checked. Examples ======== >>> from sympy import Symbol, S, tan, log, pi, sqrt >>> from sympy.sets import Interval >>> from sympy.calculus.util import continuous_domain >>> x = Symbol('x') >>> continuous_domain(1/x, x, S.Reals) Union(Interval.open(-oo, 0), Interval.open(0, oo)) >>> continuous_domain(tan(x), x, Interval(0, pi)) Union(Interval.Ropen(0, pi/2), Interval.Lopen(pi/2, pi)) >>> continuous_domain(sqrt(x - 2), x, Interval(-5, 5)) Interval(2, 5) >>> continuous_domain(log(2x - 1), x, S.Reals) Interval.open(1/2, oo) Returns ======= Interval Union of all intervals where the function is continuous. Raises ====== NotImplementedError If the method to determine continuity of such a function has not yet been developed. """ from sympy.solvers.inequalities import solve_univariate_inequality from sympy.solvers.solveset import solveset, _has_rational_power if domain.is_subset(S.Reals): constrained_interval = domain for atom in f.atoms(Pow): predicate, denomin = _has_rational_power(atom, symbol) constraint = S.EmptySet if predicate and denomin == 2: constraint = solve_univariate_inequality(atom.base >= 0, symbol).as_set() constrained_interval = Intersection(constraint, constrained_interval) for atom in f.atoms(log): constraint = solve_univariate_inequality(atom.args[0] > 0, symbol).as_set() constrained_interval = Intersection(constraint, constrained_interval) domain = constrained_interval try: sings = S.EmptySet if f.has(Abs): sings = solveset(1/f, symbol, domain) + \ solveset(denom(together(f)), symbol, domain) else: for atom in f.atoms(Pow): predicate, denomin = _has_rational_power(atom, symbol) if predicate and denomin == 2: sings = solveset(1/f, symbol, domain) +\ solveset(denom(together(f)), symbol, domain) break else: sings = Intersection(solveset(1/f, symbol), domain) + \ solveset(denom(together(f)), symbol, domain) except NotImplementedError: import sys raise (NotImplementedError("Methods for determining the continuous domains" " of this function have not been developed."), None, sys.exc_info()[2]) return domain - sings def function_range(f, symbol, domain): """ Finds the range of a function in a given domain. This method is limited by the ability to determine the singularities and determine limits. Examples ======== >>> from sympy import Symbol, S, exp, log, pi, sqrt, sin, tan >>> from sympy.sets import Interval >>> from sympy.calculus.util import function_range >>> x = Symbol('x') >>> function_range(sin(x), x, Interval(0, 2pi)) Interval(-1, 1) >>> function_range(tan(x), x, Interval(-pi/2, pi/2)) Interval(-oo, oo) >>> function_range(1/x, x, S.Reals) Union(Interval.open(-oo, 0), Interval.open(0, oo)) >>> function_range(exp(x), x, S.Reals) Interval.open(0, oo) >>> function_range(log(x), x, S.Reals) Interval(-oo, oo) >>> function_range(sqrt(x), x , Interval(-5, 9)) Interval(0, 3) """ from sympy.solvers.solveset import solveset if isinstance(domain, EmptySet): return S.EmptySet period = periodicity(f, symbol) if period is S.Zero: # the expression is constant wrt symbol return FiniteSet(f.expand()) if period is not None: if isinstance(domain, Interval): if (domain.inf - domain.sup).is_infinite: domain = Interval(0, period) elif isinstance(domain, Union): for sub_dom in domain.args: if isinstance(sub_dom, Interval) and \ ((sub_dom.inf - sub_dom.sup).is_infinite): domain = Interval(0, period) intervals = continuous_domain(f, symbol, domain) range_int = S.EmptySet if isinstance(intervals,(Interval, FiniteSet)): interval_iter = (intervals,) elif isinstance(intervals, Union): interval_iter = intervals.args else: raise NotImplementedError(filldedent(''' Unable to find range for the given domain. ''')) for interval in interval_iter: if isinstance(interval, FiniteSet): for singleton in interval: if singleton in domain: range_int += FiniteSet(f.subs(symbol, singleton)) elif isinstance(interval, Interval): vals = S.EmptySet critical_points = S.EmptySet critical_values = S.EmptySet bounds = ((interval.left_open, interval.inf, '+'), (interval.right_open, interval.sup, '-')) for is_open, limit_point, direction in bounds: if is_open: critical_values += FiniteSet(limit(f, symbol, limit_point, direction)) vals += critical_values else: vals += FiniteSet(f.subs(symbol, limit_point)) solution = solveset(f.diff(symbol), symbol, interval) if not iterable(solution): raise NotImplementedError('Unable to find critical points for {}'.format(f)) critical_points += solution for critical_point in critical_points: vals += FiniteSet(f.subs(symbol, critical_point)) left_open, right_open = False, False if critical_values is not S.EmptySet: if critical_values.inf == vals.inf: left_open = True if critical_values.sup == vals.sup: right_open = True range_int += Interval(vals.inf, vals.sup, left_open, right_open) else: raise NotImplementedError(filldedent(''' Unable to find range for the given domain. ''')) return range_int def not_empty_in(finset_intersection, syms): """ Finds the domain of the functions in `finite_set` in which the `finite_set` is not-empty Parameters ========== finset_intersection: The unevaluated intersection of FiniteSet containing real-valued functions with Union of Sets syms: Tuple of symbols Symbol for which domain is to be found Raises ====== NotImplementedError The algorithms to find the non-emptiness of the given FiniteSet are not yet implemented. ValueError The input is not valid. RuntimeError It is a bug, please report it to the github issue tracker (https://github.com/sympy/sympy/issues). Examples ======== >>> from sympy import FiniteSet, Interval, not_empty_in, oo >>> from sympy.abc import x >>> not_empty_in(FiniteSet(x/2).intersect(Interval(0, 1)), x) Interval(0, 2) >>> not_empty_in(FiniteSet(x, x2).intersect(Interval(1, 2)), x) Union(Interval(-sqrt(2), -1), Interval(1, 2)) >>> not_empty_in(FiniteSet(x2/(x + 2)).intersect(Interval(1, oo)), x) Union(Interval.Lopen(-2, -1), Interval(2, oo)) """ # TODO: handle piecewise defined functions # TODO: handle transcendental functions # TODO: handle multivariate functions if len(syms) == 0: raise ValueError("One or more symbols must be given in syms.") if finset_intersection.is_EmptySet: return EmptySet() if isinstance(finset_intersection, Union): elm_in_sets = finset_intersection.args[0] return Union(not_empty_in(finset_intersection.args[1], syms), elm_in_sets) if isinstance(finset_intersection, FiniteSet): finite_set = finset_intersection _sets = S.Reals else: finite_set = finset_intersection.args[1] _sets = finset_intersection.args[0] if not isinstance(finite_set, FiniteSet): raise ValueError('A FiniteSet must be given, not %s: %s' % (type(finite_set), finite_set)) if len(syms) == 1: symb = syms[0] else: raise NotImplementedError('more than one variables %s not handled' % (syms,)) def elm_domain(expr, intrvl): """ Finds the domain of an expression in any given interval """ from sympy.solvers.solveset import solveset _start = intrvl.start _end = intrvl.end _singularities = solveset(expr.as_numer_denom()[1], symb, domain=S.Reals) if intrvl.right_open: if _end is S.Infinity: _domain1 = S.Reals else: _domain1 = solveset(expr < _end, symb, domain=S.Reals) else: _domain1 = solveset(expr <= _end, symb, domain=S.Reals) if intrvl.left_open: if _start is S.NegativeInfinity: _domain2 = S.Reals else: _domain2 = solveset(expr > _start, symb, domain=S.Reals) else: _domain2 = solveset(expr >= _start, symb, domain=S.Reals) # domain in the interval expr_with_sing = Intersection(_domain1, _domain2) expr_domain = Complement(expr_with_sing, _singularities) return expr_domain if isinstance(_sets, Interval): return Union([elm_domain(element, _sets) for element in finite_set]) if isinstance(_sets, Union): _domain = S.EmptySet for intrvl in _sets.args: _domain_element = Union([elm_domain(element, intrvl) for element in finite_set]) _domain = Union(_domain, _domain_element) return _domain def periodicity(f, symbol, check=False): """ Tests the given function for periodicity in the given symbol. Parameters ========== f : Expr. The concerned function. symbol : Symbol The variable for which the period is to be determined. check : Boolean The flag to verify whether the value being returned is a period or not. Returns ======= period The period of the function is returned. `None` is returned when the function is aperiodic or has a complex period. The value of `0` is returned as the period of a constant function. Raises ====== NotImplementedError The value of the period computed cannot be verified. Notes ===== Currently, we do not support functions with a complex period. The period of functions having complex periodic values such as `exp`, `sinh` is evaluated to `None`. The value returned might not be the "fundamental" period of the given function i.e. it may not be the smallest periodic value of the function. The verification of the period through the `check` flag is not reliable due to internal simplification of the given expression. Hence, it is set to `False` by default. Examples ======== >>> from sympy import Symbol, sin, cos, tan, exp >>> from sympy.calculus.util import periodicity >>> x = Symbol('x') >>> f = sin(x) + sin(2x) + sin(3x) >>> periodicity(f, x) 2pi >>> periodicity(sin(x)cos(x), x) pi >>> periodicity(exp(tan(2x) - 1), x) pi/2 >>> periodicity(sin(4x)*cos(2x), x) pi >>> periodicity(exp(x), x) """ from sympy.core.function import diff from sympy.core.mod import Mod from sympy.core.relational import Relational from sympy.functions.elementary.complexes import Abs from sympy.functions.elementary.trigonometric import ( TrigonometricFunction, sin, cos, csc, sec) from sympy.simplify.simplify import simplify from sympy.solvers.decompogen import decompogen from sympy.polys.polytools import degree, lcm_list def _check(orig_f, period): '''Return the checked period or raise an error.''' new_f = orig_f.subs(symbol, symbol + period) if new_f.equals(orig_f): return period else: raise NotImplementedError(filldedent(''' The period of the given function cannot be verified. When `%s` was replaced with `%s + %s` in `%s`, the result was `%s` which was not recognized as being the same as the original function. So either the period was wrong or the two forms were not recognized as being equal. Set check=False to obtain the value.''' % (symbol, symbol, period, orig_f, new_f))) orig_f = f period = None if isinstance(f, Relational): f = f.lhs - f.rhs f = simplify(f) if symbol not in f.free_symbols: return S.Zero if isinstance(f, TrigonometricFunction): try: period = f.period(symbol) except NotImplementedError: pass if isinstance(f, Abs): arg = f.args[0] if isinstance(arg, (sec, csc, cos)): # all but tan and cot might have a # a period that is half as large # so recast as sin arg = sin(arg.args[0]) period = periodicity(arg, symbol) if period is not None and isinstance(arg, sin): # the argument of Abs was a trigonometric other than # cot or tan; test to see if the half-period # is valid. Abs(arg) has behaviour equivalent to # orig_f, so use that for test: orig_f = Abs(arg) try: return _check(orig_f, period/2) except NotImplementedError as err: if check: raise NotImplementedError(err) # else let new orig_f and period be # checked below if f.is_Pow: base, expo = f.args base_has_sym = base.has(symbol) expo_has_sym = expo.has(symbol) if base_has_sym and not expo_has_sym: period = periodicity(base, symbol) elif expo_has_sym and not base_has_sym: period = periodicity(expo, symbol) else: period = _periodicity(f.args, symbol) elif f.is_Mul: coeff, g = f.as_independent(symbol, as_Add=False) if isinstance(g, TrigonometricFunction) or coeff is not S.One: period = periodicity(g, symbol) else: period = _periodicity(g.args, symbol) elif f.is_Add: k, g = f.as_independent(symbol) if k is not S.Zero: return periodicity(g, symbol) period = _periodicity(g.args, symbol) elif isinstance(f, Mod): a, n = f.args if a == symbol: period = n elif isinstance(a, TrigonometricFunction): period = periodicity(a, symbol) #check if 'f' is linear in 'symbol' elif (a.is_polynomial(symbol) and degree(a, symbol) == 1 and symbol not in n.free_symbols): period = Abs(n / a.diff(symbol)) elif period is None: from sympy.solvers.decompogen import compogen g_s = decompogen(f, symbol) num_of_gs = len(g_s) if num_of_gs > 1: for index, g in enumerate(reversed(g_s)): start_index = num_of_gs - 1 - index g = compogen(g_s[start_index:], symbol) if g != orig_f and g != f: # Fix for issue 12620 period = periodicity(g, symbol) if period is not None: break if period is not None: if check: return _check(orig_f, period) return period return None def _periodicity(args, symbol): """Helper for periodicity to find the period of a list of simpler functions. It uses the `lcim` method to find the least common period of all the functions. """ periods = [] for f in args: period = periodicity(f, symbol) if period is None: return None if period is not S.Zero: periods.append(period) if len(periods) > 1: return lcim(periods) return periods[0] def lcim(numbers): """Returns the least common integral multiple of a list of numbers. The numbers can be rational or irrational or a mixture of both. `None` is returned for incommensurable numbers. Examples ======== >>> from sympy import S, pi >>> from sympy.calculus.util import lcim >>> lcim([S(1)/2, S(3)/4, S(5)/6]) 15/2 >>> lcim([2pi, 3pi, pi, pi/2]) 6pi >>> lcim([S(1), 2pi]) """ result = None if all(num.is_irrational for num in numbers): factorized_nums = list(map(lambda num: num.factor(), numbers)) factors_num = list( map(lambda num: num.as_coeff_Mul(), factorized_nums)) term = factors_num[0][1] if all(factor == term for coeff, factor in factors_num): common_term = term coeffs = [coeff for coeff, factor in factors_num] result = lcm_list(coeffs) * common_term elif all(num.is_rational for num in numbers): result = lcm_list(numbers) else: pass return result class AccumulationBounds(AtomicExpr): r""" # Note AccumulationBounds has an alias: AccumBounds AccumulationBounds represent an interval `[a, b]`, which is always closed at the ends. Here `a` and `b` can be any value from extended real numbers. The intended meaning of AccummulationBounds is to give an approximate location of the accumulation points of a real function at a limit point. Let `a` and `b` be reals such that a <= b. `\left\langle a, b\right\rangle = \{x \in \mathbb{R} \mid a \le x \le b\}` `\left\langle -\infty, b\right\rangle = \{x \in \mathbb{R} \mid x \le b\} \cup \{-\infty, \infty\}` `\left\langle a, \infty \right\rangle = \{x \in \mathbb{R} \mid a \le x\} \cup \{-\infty, \infty\}` `\left\langle -\infty, \infty \right\rangle = \mathbb{R} \cup \{-\infty, \infty\}` `oo` and `-oo` are added to the second and third definition respectively, since if either `-oo` or `oo` is an argument, then the other one should be included (though not as an end point). This is forced, since we have, for example, `1/AccumBounds(0, 1) = AccumBounds(1, oo)`, and the limit at `0` is not one-sided. As x tends to `0-`, then `1/x -> -oo`, so `-oo` should be interpreted as belonging to `AccumBounds(1, oo)` though it need not appear explicitly. In many cases it suffices to know that the limit set is bounded. However, in some other cases more exact information could be useful. For example, all accumulation values of cos(x) + 1 are non-negative. (AccumBounds(-1, 1) + 1 = AccumBounds(0, 2)) A AccumulationBounds object is defined to be real AccumulationBounds, if its end points are finite reals. Let `X`, `Y` be real AccumulationBounds, then their sum, difference, product are defined to be the following sets: `X + Y = \{ x+y \mid x \in X \cap y \in Y\}` `X - Y = \{ x-y \mid x \in X \cap y \in Y\}` `X * Y = \{ xy \mid x \in X \cap y \in Y\}` There is, however, no consensus on Interval division. `X / Y = \{ z \mid \exists x \in X, y \in Y \mid y \neq 0, z = x/y\}` Note: According to this definition the quotient of two AccumulationBounds may not be a AccumulationBounds object but rather a union of AccumulationBounds. Note ==== The main focus in the interval arithmetic is on the simplest way to calculate upper and lower endpoints for the range of values of a function in one or more variables. These barriers are not necessarily the supremum or infimum, since the precise calculation of those values can be difficult or impossible. Examples ======== >>> from sympy import AccumBounds, sin, exp, log, pi, E, S, oo >>> from sympy.abc import x >>> AccumBounds(0, 1) + AccumBounds(1, 2) AccumBounds(1, 3) >>> AccumBounds(0, 1) - AccumBounds(0, 2) AccumBounds(-2, 1) >>> AccumBounds(-2, 3)AccumBounds(-1, 1) AccumBounds(-3, 3) >>> AccumBounds(1, 2)AccumBounds(3, 5) AccumBounds(3, 10) The exponentiation of AccumulationBounds is defined as follows: If 0 does not belong to `X` or `n > 0` then `X^n = \{ x^n \mid x \in X\}` otherwise `X^n = \{ x^n \mid x \neq 0, x \in X\} \cup \{-\infty, \infty\}` Here for fractional `n`, the part of `X` resulting in a complex AccumulationBounds object is neglected. >>> AccumBounds(-1, 4)(S(1)/2) AccumBounds(0, 2) >>> AccumBounds(1, 2)2 AccumBounds(1, 4) >>> AccumBounds(-1, oo)(-1) AccumBounds(-oo, oo) Note: `<a, b>^2` is not same as `<a, b><a, b>` >>> AccumBounds(-1, 1)2 AccumBounds(0, 1) >>> AccumBounds(1, 3) < 4 True >>> AccumBounds(1, 3) < -1 False Some elementary functions can also take AccumulationBounds as input. A function `f` evaluated for some real AccumulationBounds `<a, b>` is defined as `f(\left\langle a, b\right\rangle) = \{ f(x) \mid a \le x \le b \}` >>> sin(AccumBounds(pi/6, pi/3)) AccumBounds(1/2, sqrt(3)/2) >>> exp(AccumBounds(0, 1)) AccumBounds(1, E) >>> log(AccumBounds(1, E)) AccumBounds(0, 1) Some symbol in an expression can be substituted for a AccumulationBounds object. But it doesn't necessarily evaluate the AccumulationBounds for that expression. Same expression can be evaluated to different values depending upon the form it is used for substitution. For example: >>> (x2 + 2x + 1).subs(x, AccumBounds(-1, 1)) AccumBounds(-1, 4) >>> ((x + 1)2).subs(x, AccumBounds(-1, 1)) AccumBounds(0, 4) References ========== .. [1] https://en.wikipedia.org/wiki/Interval_arithmetic .. [2] http://fab.cba.mit.edu/classes/S62.12/docs/Hickey_interval.pdf Notes ===== Do not use ``AccumulationBounds`` for floating point interval arithmetic calculations, use ``mpmath.iv`` instead. """ is_real = True def __new__(cls, min, max): min = _sympify(min) max = _sympify(max) inftys = [S.Infinity, S.NegativeInfinity] # Only allow real intervals (use symbols with 'is_real=True'). if not (min.is_real or min in inftys) \ or not (max.is_real or max in inftys): raise ValueError("Only real AccumulationBounds are supported") # Make sure that the created AccumBounds object will be valid. if max.is_comparable and min.is_comparable: if max < min: raise ValueError( "Lower limit should be smaller than upper limit") if max == min: return max return Basic.__new__(cls, min, max) # setting the operation priority _op_priority = 11.0 @property def min(self): """ Returns the minimum possible value attained by AccumulationBounds object. Examples ======== >>> from sympy import AccumBounds >>> AccumBounds(1, 3).min 1 """ return self.args[0] @property def max(self): """ Returns the maximum possible value attained by AccumulationBounds object. Examples ======== >>> from sympy import AccumBounds >>> AccumBounds(1, 3).max 3 """ return self.args[1] @property def delta(self): """ Returns the difference of maximum possible value attained by AccumulationBounds object and minimum possible value attained by AccumulationBounds object. Examples ======== >>> from sympy import AccumBounds >>> AccumBounds(1, 3).delta 2 """ return self.max - self.min @property def mid(self): """ Returns the mean of maximum possible value attained by AccumulationBounds object and minimum possible value attained by AccumulationBounds object. Examples ======== >>> from sympy import AccumBounds >>> AccumBounds(1, 3).mid 2 """ return (self.min + self.max) / 2 @_sympifyit('other', NotImplemented) def _eval_power(self, other): return self.__pow__(other) @_sympifyit('other', NotImplemented) def __add__(self, other): if isinstance(other, Expr): if isinstance(other, AccumBounds): return AccumBounds( Add(self.min, other.min), Add(self.max, other.max)) if other is S.Infinity and self.min is S.NegativeInfinity or \ other is S.NegativeInfinity and self.max is S.Infinity: return AccumBounds(-oo, oo) elif other.is_real: return AccumBounds(Add(self.min, other), Add(self.max, other)) return Add(self, other, evaluate=False) return NotImplemented __radd__ = __add__ def __neg__(self): return AccumBounds(-self.max, -self.min) @_sympifyit('other', NotImplemented) def __sub__(self, other): if isinstance(other, Expr): if isinstance(other, AccumBounds): return AccumBounds( Add(self.min, -other.max), Add(self.max, -other.min)) if other is S.NegativeInfinity and self.min is S.NegativeInfinity or \ other is S.Infinity and self.max is S.Infinity: return AccumBounds(-oo, oo) elif other.is_real: return AccumBounds( Add(self.min, -other), Add(self.max, -other)) return Add(self, -other, evaluate=False) return NotImplemented @_sympifyit('other', NotImplemented) def __rsub__(self, other): return self.__neg__() + other @_sympifyit('other', NotImplemented) def __mul__(self, other): if isinstance(other, Expr): if isinstance(other, AccumBounds): return AccumBounds(Min(Mul(self.min, other.min), Mul(self.min, other.max), Mul(self.max, other.min), Mul(self.max, other.max)), Max(Mul(self.min, other.min), Mul(self.min, other.max), Mul(self.max, other.min), Mul(self.max, other.max))) if other is S.Infinity: if self.min.is_zero: return AccumBounds(0, oo) if self.max.is_zero: return AccumBounds(-oo, 0) if other is S.NegativeInfinity: if self.min.is_zero: return AccumBounds(-oo, 0) if self.max.is_zero: return AccumBounds(0, oo) if other.is_real: if other.is_zero: if self == AccumBounds(-oo, oo): return AccumBounds(-oo, oo) if self.max is S.Infinity: return AccumBounds(0, oo) if self.min is S.NegativeInfinity: return AccumBounds(-oo, 0) return S.Zero if other.is_positive: return AccumBounds( Mul(self.min, other), Mul(self.max, other)) elif other.is_negative: return AccumBounds( Mul(self.max, other), Mul(self.min, other)) if isinstance(other, Order): return other return Mul(self, other, evaluate=False) return NotImplemented __rmul__ = __mul__ @_sympifyit('other', NotImplemented) def __div__(self, other): if isinstance(other, Expr): if isinstance(other, AccumBounds): if S.Zero not in other: return self AccumBounds(1/other.max, 1/other.min) if S.Zero in self and S.Zero in other: if self.min.is_zero and other.min.is_zero: return AccumBounds(0, oo) if self.max.is_zero and other.min.is_zero: return AccumBounds(-oo, 0) return AccumBounds(-oo, oo) if self.max.is_negative: if other.min.is_negative: if other.max.is_zero: return AccumBounds(self.max / other.min, oo) if other.max.is_positive: # the actual answer is a Union of AccumBounds, # Union(AccumBounds(-oo, self.max/other.max), # AccumBounds(self.max/other.min, oo)) return AccumBounds(-oo, oo) if other.min.is_zero and other.max.is_positive: return AccumBounds(-oo, self.max / other.max) if self.min.is_positive: if other.min.is_negative: if other.max.is_zero: return AccumBounds(-oo, self.min / other.min) if other.max.is_positive: # the actual answer is a Union of AccumBounds, # Union(AccumBounds(-oo, self.min/other.min), # AccumBounds(self.min/other.max, oo)) return AccumBounds(-oo, oo) if other.min.is_zero and other.max.is_positive: return AccumBounds(self.min / other.max, oo) elif other.is_real: if other is S.Infinity or other is S.NegativeInfinity: if self == AccumBounds(-oo, oo): return AccumBounds(-oo, oo) if self.max is S.Infinity: return AccumBounds(Min(0, other), Max(0, other)) if self.min is S.NegativeInfinity: return AccumBounds(Min(0, -other), Max(0, -other)) if other.is_positive: return AccumBounds(self.min / other, self.max / other) elif other.is_negative: return AccumBounds(self.max / other, self.min / other) return Mul(self, 1 / other, evaluate=False) return NotImplemented __truediv__ = __div__ @_sympifyit('other', NotImplemented) def __rdiv__(self, other): if isinstance(other, Expr): if other.is_real: if other.is_zero: return S.Zero if S.Zero in self: if self.min == S.Zero: if other.is_positive: return AccumBounds(Mul(other, 1 / self.max), oo) if other.is_negative: return AccumBounds(-oo, Mul(other, 1 / self.max)) if self.max == S.Zero: if other.is_positive: return AccumBounds(-oo, Mul(other, 1 / self.min)) if other.is_negative: return AccumBounds(Mul(other, 1 / self.min), oo) return AccumBounds(-oo, oo) else: return AccumBounds(Min(other / self.min, other / self.max), Max(other / self.min, other / self.max)) return Mul(other, 1 / self, evaluate=False) else: return NotImplemented __rtruediv__ = __rdiv__ @_sympifyit('other', NotImplemented) def __pow__(self, other): from sympy.functions.elementary.miscellaneous import real_root if isinstance(other, Expr): if other is S.Infinity: if self.min.is_nonnegative: if self.max < 1: return S.Zero if self.min > 1: return S.Infinity return AccumBounds(0, oo) elif self.max.is_negative: if self.min > -1: return S.Zero if self.max < -1: return FiniteSet(-oo, oo) return AccumBounds(-oo, oo) else: if self.min > -1: if self.max < 1: return S.Zero return AccumBounds(0, oo) return AccumBounds(-oo, oo) if other is S.NegativeInfinity: return (1 / self)oo if other.is_real and other.is_number: if other.is_zero: return S.One if other.is_Integer: if self.min.is_positive: return AccumBounds( Min(self.min other, self.max other), Max(self.min other, self.max other)) elif self.max.is_negative: return AccumBounds( Min(self.max other, self.min other), Max(self.max other, self.min other)) if other % 2 == 0: if other.is_negative: if self.min.is_zero: return AccumBounds(self.maxother, oo) if self.max.is_zero: return AccumBounds(self.minother, oo) return AccumBounds(0, oo) return AccumBounds( S.Zero, Max(self.minother, self.maxother)) else: if other.is_negative: if self.min.is_zero: return AccumBounds(self.maxother, oo) if self.max.is_zero: return AccumBounds(-oo, self.minother) return AccumBounds(-oo, oo) return AccumBounds(self.minother, self.maxother) num, den = other.as_numer_denom() if num == S(1): if den % 2 == 0: if S.Zero in self: if self.min.is_negative: return AccumBounds(0, real_root(self.max, den)) return AccumBounds(real_root(self.min, den), real_root(self.max, den)) num_pow = selfnum return num_pow**(1 / den) return Pow(self, other, evaluate=False) return NotImplemented def __abs__(self): if self.max.is_negative: return self.__neg__() elif self.min.is_negative: return AccumBounds(S.Zero, Max(abs(self.min), self.max)) else: return self def __lt__(self, other): """ Returns True if range of values attained by `self` AccumulationBounds object is less than the range of values attained by `other`, where other may be any value of type AccumulationBounds object or extended real number value, False if `other` satisfies the same property, else an unevaluated Relational Examples ======== >>> from sympy import AccumBounds, oo >>> AccumBounds(1, 3) < AccumBounds(4, oo) True >>> AccumBounds(1, 4) < AccumBounds(3, 4) AccumBounds(1, 4) < AccumBounds(3, 4) >>> AccumBounds(1, oo) < -1 False """ other = _sympify(other) if isinstance(other, AccumBounds): if self.max < other.min: return True if self.min >= other.max: return False elif not(other.is_real or other is S.Infinity or other is S.NegativeInfinity): raise TypeError( "Invalid comparison of %s %s" % (type(other), other)) elif other.is_comparable: if self.max < other: return True if self.min >= other: return False return super(AccumulationBounds, self).__lt__(other) def __le__(self, other): """ Returns True if range of values attained by `self` AccumulationBounds object is less than or equal to the range of values attained by `other`, where other may be any value of type AccumulationBounds object or extended real number value, False if `other` satisfies the same property, else an unevaluated Relational. Examples ======== >>> from sympy import AccumBounds, oo >>> AccumBounds(1, 3) <= AccumBounds(4, oo) True >>> AccumBounds(1, 4) <= AccumBounds(3, 4) AccumBounds(1, 4) <= AccumBounds(3, 4) >>> AccumBounds(1, 3) <= 0 False """ other = _sympify(other) if isinstance(other, AccumBounds): if self.max <= other.min: return True if self.min > other.max: return False elif not(other.is_real or other is S.Infinity or other is S.NegativeInfinity): raise TypeError( "Invalid comparison of %s %s" % (type(other), other)) elif other.is_comparable: if self.max <= other: return True if self.min > other: return False return super(AccumulationBounds, self).__le__(other) def __gt__(self, other): """ Returns True if range of values attained by `self` AccumulationBounds object is greater than the range of values attained by `other`, where other may be any value of type AccumulationBounds object or extended real number value, False if `other` satisfies the same property, else an unevaluated Relational. Examples ======== >>> from sympy import AccumBounds, oo >>> AccumBounds(1, 3) > AccumBounds(4, oo) False >>> AccumBounds(1, 4) > AccumBounds(3, 4) AccumBounds(1, 4) > AccumBounds(3, 4) >>> AccumBounds(1, oo) > -1 True """ other = _sympify(other) if isinstance(other, AccumBounds): if self.min > other.max: return True if self.max <= other.min: return False elif not(other.is_real or other is S.Infinity or other is S.NegativeInfinity): raise TypeError( "Invalid comparison of %s %s" % (type(other), other)) elif other.is_comparable: if self.min > other: return True if self.max <= other: return False return super(AccumulationBounds, self).__gt__(other) def __ge__(self, other): """ Returns True if range of values attained by `self` AccumulationBounds object is less that the range of values attained by `other`, where other may be any value of type AccumulationBounds object or extended real number value, False if `other` satisfies the same property, else an unevaluated Relational. Examples ======== >>> from sympy import AccumBounds, oo >>> AccumBounds(1, 3) >= AccumBounds(4, oo) False >>> AccumBounds(1, 4) >= AccumBounds(3, 4) AccumBounds(1, 4) >= AccumBounds(3, 4) >>> AccumBounds(1, oo) >= 1 True """ other = _sympify(other) if isinstance(other, AccumBounds): if self.min >= other.max: return True if self.max < other.min: return False elif not(other.is_real or other is S.Infinity or other is S.NegativeInfinity): raise TypeError( "Invalid comparison of %s %s" % (type(other), other)) elif other.is_comparable: if self.min >= other: return True if self.max < other: return False return super(AccumulationBounds, self).__ge__(other) def __contains__(self, other): """ Returns True if other is contained in self, where other belongs to extended real numbers, False if not contained, otherwise TypeError is raised. Examples ======== >>> from sympy import AccumBounds, oo >>> 1 in AccumBounds(-1, 3) True -oo and oo go together as limits (in AccumulationBounds). >>> -oo in AccumBounds(1, oo) True >>> oo in AccumBounds(-oo, 0) True """ other = _sympify(other) if other is S.Infinity or other is S.NegativeInfinity: if self.min is S.NegativeInfinity or self.max is S.Infinity: return True return False rv = And(self.min <= other, self.max >= other) if rv not in (True, False): raise TypeError("input failed to evaluate") return rv def intersection(self, other): """ Returns the intersection of 'self' and 'other'. Here other can be an instance of FiniteSet or AccumulationBounds. Examples ======== >>> from sympy import AccumBounds, FiniteSet >>> AccumBounds(1, 3).intersection(AccumBounds(2, 4)) AccumBounds(2, 3) >>> AccumBounds(1, 3).intersection(AccumBounds(4, 6)) EmptySet() >>> AccumBounds(1, 4).intersection(FiniteSet(1, 2, 5)) {1, 2} """ if not isinstance(other, (AccumBounds, FiniteSet)): raise TypeError( "Input must be AccumulationBounds or FiniteSet object") if isinstance(other, FiniteSet): fin_set = S.EmptySet for i in other: if i in self: fin_set = fin_set + FiniteSet(i) return fin_set if self.max < other.min or self.min > other.max: return S.EmptySet if self.min <= other.min: if self.max <= other.max: return AccumBounds(other.min, self.max) if self.max > other.max: return other if other.min <= self.min: if other.max < self.max: return AccumBounds(self.min, other.max) if other.max > self.max: return self def union(self, other): # TODO : Devise a better method for Union of AccumBounds # this method is not actually correct and # can be made better if not isinstance(other, AccumBounds): raise TypeError( "Input must be AccumulationBounds or FiniteSet object") if self.min <= other.min and self.max >= other.min: return AccumBounds(self.min, Max(self.max, other.max)) if other.min <= self.min and other.max >= self.min: return AccumBounds(other.min, Max(self.max, other.max)) # setting an alias for AccumulationBounds AccumBounds = AccumulationBounds
15d322f514f373221a11c72110ac941cc78b583198959644d8a6b96804813314	""" module for generating C, C++, Fortran77, Fortran90, Julia, Rust and Octave/Matlab routines that evaluate sympy expressions. This module is work in progress. Only the milestones with a '+' character in the list below have been completed. --- How is sympy.utilities.codegen different from sympy.printing.ccode? --- We considered the idea to extend the printing routines for sympy functions in such a way that it prints complete compilable code, but this leads to a few unsurmountable issues that can only be tackled with dedicated code generator: - For C, one needs both a code and a header file, while the printing routines generate just one string. This code generator can be extended to support .pyf files for f2py. - SymPy functions are not concerned with programming-technical issues, such as input, output and input-output arguments. Other examples are contiguous or non-contiguous arrays, including headers of other libraries such as gsl or others. - It is highly interesting to evaluate several sympy functions in one C routine, eventually sharing common intermediate results with the help of the cse routine. This is more than just printing. - From the programming perspective, expressions with constants should be evaluated in the code generator as much as possible. This is different for printing. --- Basic assumptions --- * A generic Routine data structure describes the routine that must be translated into C/Fortran/... code. This data structure covers all features present in one or more of the supported languages. * Descendants from the CodeGen class transform multiple Routine instances into compilable code. Each derived class translates into a specific language. * In many cases, one wants a simple workflow. The friendly functions in the last part are a simple api on top of the Routine/CodeGen stuff. They are easier to use, but are less powerful. --- Milestones --- + First working version with scalar input arguments, generating C code, tests + Friendly functions that are easier to use than the rigorous Routine/CodeGen workflow. + Integer and Real numbers as input and output + Output arguments + InputOutput arguments + Sort input/output arguments properly + Contiguous array arguments (numpy matrices) + Also generate .pyf code for f2py (in autowrap module) + Isolate constants and evaluate them beforehand in double precision + Fortran 90 + Octave/Matlab - Common Subexpression Elimination - User defined comments in the generated code - Optional extra include lines for libraries/objects that can eval special functions - Test other C compilers and libraries: gcc, tcc, libtcc, gcc+gsl, ... - Contiguous array arguments (sympy matrices) - Non-contiguous array arguments (sympy matrices) - ccode must raise an error when it encounters something that can not be translated into c. ccode(integrate(sin(x)/x, x)) does not make sense. - Complex numbers as input and output - A default complex datatype - Include extra information in the header: date, user, hostname, sha1 hash, ... - Fortran 77 - C++ - Python - Julia - Rust - ... """ from __future__ import print_function, division import os import textwrap from sympy import __version__ as sympy_version from sympy.core import Symbol, S, Tuple, Equality, Function, Basic from sympy.core.compatibility import is_sequence, StringIO, string_types from sympy.printing.ccode import c_code_printers from sympy.printing.codeprinter import AssignmentError from sympy.printing.fcode import FCodePrinter from sympy.printing.julia import JuliaCodePrinter from sympy.printing.octave import OctaveCodePrinter from sympy.printing.rust import RustCodePrinter from sympy.tensor import Idx, Indexed, IndexedBase from sympy.matrices import (MatrixSymbol, ImmutableMatrix, MatrixBase, MatrixExpr, MatrixSlice) __all__ = [ # description of routines "Routine", "DataType", "default_datatypes", "get_default_datatype", "Argument", "InputArgument", "OutputArgument", "Result", # routines -> code "CodeGen", "CCodeGen", "FCodeGen", "JuliaCodeGen", "OctaveCodeGen", "RustCodeGen", # friendly functions "codegen", "make_routine", ] # # Description of routines # class Routine(object): """Generic description of evaluation routine for set of expressions. A CodeGen class can translate instances of this class into code in a particular language. The routine specification covers all the features present in these languages. The CodeGen part must raise an exception when certain features are not present in the target language. For example, multiple return values are possible in Python, but not in C or Fortran. Another example: Fortran and Python support complex numbers, while C does not. """ def __init__(self, name, arguments, results, local_vars, global_vars): """Initialize a Routine instance. Parameters ========== name : string Name of the routine. arguments : list of Arguments These are things that appear in arguments of a routine, often appearing on the right-hand side of a function call. These are commonly InputArguments but in some languages, they can also be OutputArguments or InOutArguments (e.g., pass-by-reference in C code). results : list of Results These are the return values of the routine, often appearing on the left-hand side of a function call. The difference between Results and OutputArguments and when you should use each is language-specific. local_vars : list of Results These are variables that will be defined at the beginning of the function. global_vars : list of Symbols Variables which will not be passed into the function. """ # extract all input symbols and all symbols appearing in an expression input_symbols = set([]) symbols = set([]) for arg in arguments: if isinstance(arg, OutputArgument): symbols.update(arg.expr.free_symbols - arg.expr.atoms(Indexed)) elif isinstance(arg, InputArgument): input_symbols.add(arg.name) elif isinstance(arg, InOutArgument): input_symbols.add(arg.name) symbols.update(arg.expr.free_symbols - arg.expr.atoms(Indexed)) else: raise ValueError("Unknown Routine argument: %s" % arg) for r in results: if not isinstance(r, Result): raise ValueError("Unknown Routine result: %s" % r) symbols.update(r.expr.free_symbols - r.expr.atoms(Indexed)) local_symbols = set() for r in local_vars: if isinstance(r, Result): symbols.update(r.expr.free_symbols - r.expr.atoms(Indexed)) local_symbols.add(r.name) else: local_symbols.add(r) symbols = set([s.label if isinstance(s, Idx) else s for s in symbols]) # Check that all symbols in the expressions are covered by # InputArguments/InOutArguments---subset because user could # specify additional (unused) InputArguments or local_vars. notcovered = symbols.difference( input_symbols.union(local_symbols).union(global_vars)) if notcovered != set([]): raise ValueError("Symbols needed for output are not in input " + ", ".join([str(x) for x in notcovered])) self.name = name self.arguments = arguments self.results = results self.local_vars = local_vars self.global_vars = global_vars def __str__(self): return self.__class__.__name__ + "({name!r}, {arguments}, {results}, {local_vars}, {global_vars})".format(*self.__dict__) __repr__ = __str__ @property def variables(self): """Returns a set of all variables possibly used in the routine. For routines with unnamed return values, the dummies that may or may not be used will be included in the set. """ v = set(self.local_vars) for arg in self.arguments: v.add(arg.name) for res in self.results: v.add(res.result_var) return v @property def result_variables(self): """Returns a list of OutputArgument, InOutArgument and Result. If return values are present, they are at the end ot the list. """ args = [arg for arg in self.arguments if isinstance( arg, (OutputArgument, InOutArgument))] args.extend(self.results) return args class DataType(object): """Holds strings for a certain datatype in different languages.""" def __init__(self, cname, fname, pyname, jlname, octname, rsname): self.cname = cname self.fname = fname self.pyname = pyname self.jlname = jlname self.octname = octname self.rsname = rsname default_datatypes = { "int": DataType("int", "INTEGER4", "int", "", "", "i32"), "float": DataType("double", "REAL8", "float", "", "", "f64"), } def get_default_datatype(expr): """Derives an appropriate datatype based on the expression.""" if expr.is_integer: return default_datatypes["int"] elif isinstance(expr, MatrixBase): for element in expr: if not element.is_integer: return default_datatypes["float"] return default_datatypes["int"] else: return default_datatypes["float"] class Variable(object): """Represents a typed variable.""" def __init__(self, name, datatype=None, dimensions=None, precision=None): """Return a new variable. Parameters ========== name : Symbol or MatrixSymbol datatype : optional When not given, the data type will be guessed based on the assumptions on the symbol argument. dimension : sequence containing tupes, optional If present, the argument is interpreted as an array, where this sequence of tuples specifies (lower, upper) bounds for each index of the array. precision : int, optional Controls the precision of floating point constants. """ if not isinstance(name, (Symbol, MatrixSymbol)): raise TypeError("The first argument must be a sympy symbol.") if datatype is None: datatype = get_default_datatype(name) elif not isinstance(datatype, DataType): raise TypeError("The (optional) `datatype' argument must be an " "instance of the DataType class.") if dimensions and not isinstance(dimensions, (tuple, list)): raise TypeError( "The dimension argument must be a sequence of tuples") self._name = name self._datatype = { 'C': datatype.cname, 'FORTRAN': datatype.fname, 'JULIA': datatype.jlname, 'OCTAVE': datatype.octname, 'PYTHON': datatype.pyname, 'RUST': datatype.rsname, } self.dimensions = dimensions self.precision = precision def __str__(self): return "%s(%r)" % (self.__class__.__name__, self.name) __repr__ = __str__ @property def name(self): return self._name def get_datatype(self, language): """Returns the datatype string for the requested language. Examples ======== >>> from sympy import Symbol >>> from sympy.utilities.codegen import Variable >>> x = Variable(Symbol('x')) >>> x.get_datatype('c') 'double' >>> x.get_datatype('fortran') 'REAL8' """ try: return self._datatype[language.upper()] except KeyError: raise CodeGenError("Has datatypes for languages: %s" % ", ".join(self._datatype)) class Argument(Variable): """An abstract Argument data structure: a name and a data type. This structure is refined in the descendants below. """ pass class InputArgument(Argument): pass class ResultBase(object): """Base class for all "outgoing" information from a routine. Objects of this class stores a sympy expression, and a sympy object representing a result variable that will be used in the generated code only if necessary. """ def __init__(self, expr, result_var): self.expr = expr self.result_var = result_var def __str__(self): return "%s(%r, %r)" % (self.__class__.__name__, self.expr, self.result_var) __repr__ = __str__ class OutputArgument(Argument, ResultBase): """OutputArgument are always initialized in the routine.""" def __init__(self, name, result_var, expr, datatype=None, dimensions=None, precision=None): """Return a new variable. Parameters ========== name : Symbol, MatrixSymbol The name of this variable. When used for code generation, this might appear, for example, in the prototype of function in the argument list. result_var : Symbol, Indexed Something that can be used to assign a value to this variable. Typically the same as `name` but for Indexed this should be e.g., "y[i]" whereas `name` should be the Symbol "y". expr : object The expression that should be output, typically a SymPy expression. datatype : optional When not given, the data type will be guessed based on the assumptions on the symbol argument. dimension : sequence containing tupes, optional If present, the argument is interpreted as an array, where this sequence of tuples specifies (lower, upper) bounds for each index of the array. precision : int, optional Controls the precision of floating point constants. """ Argument.__init__(self, name, datatype, dimensions, precision) ResultBase.__init__(self, expr, result_var) def __str__(self): return "%s(%r, %r, %r)" % (self.__class__.__name__, self.name, self.result_var, self.expr) __repr__ = __str__ class InOutArgument(Argument, ResultBase): """InOutArgument are never initialized in the routine.""" def __init__(self, name, result_var, expr, datatype=None, dimensions=None, precision=None): if not datatype: datatype = get_default_datatype(expr) Argument.__init__(self, name, datatype, dimensions, precision) ResultBase.__init__(self, expr, result_var) __init__.__doc__ = OutputArgument.__init__.__doc__ def __str__(self): return "%s(%r, %r, %r)" % (self.__class__.__name__, self.name, self.expr, self.result_var) __repr__ = __str__ class Result(Variable, ResultBase): """An expression for a return value. The name result is used to avoid conflicts with the reserved word "return" in the python language. It is also shorter than ReturnValue. These may or may not need a name in the destination (e.g., "return(xy)" might return a value without ever naming it). """ def __init__(self, expr, name=None, result_var=None, datatype=None, dimensions=None, precision=None): """Initialize a return value. Parameters ========== expr : SymPy expression name : Symbol, MatrixSymbol, optional The name of this return variable. When used for code generation, this might appear, for example, in the prototype of function in a list of return values. A dummy name is generated if omitted. result_var : Symbol, Indexed, optional Something that can be used to assign a value to this variable. Typically the same as `name` but for Indexed this should be e.g., "y[i]" whereas `name` should be the Symbol "y". Defaults to `name` if omitted. datatype : optional When not given, the data type will be guessed based on the assumptions on the symbol argument. dimension : sequence containing tupes, optional If present, this variable is interpreted as an array, where this sequence of tuples specifies (lower, upper) bounds for each index of the array. precision : int, optional Controls the precision of floating point constants. """ # Basic because it is the base class for all types of expressions if not isinstance(expr, (Basic, MatrixBase)): raise TypeError("The first argument must be a sympy expression.") if name is None: name = 'result_%d' % abs(hash(expr)) if isinstance(name, string_types): if isinstance(expr, (MatrixBase, MatrixExpr)): name = MatrixSymbol(name, expr.shape) else: name = Symbol(name) if result_var is None: result_var = name Variable.__init__(self, name, datatype=datatype, dimensions=dimensions, precision=precision) ResultBase.__init__(self, expr, result_var) def __str__(self): return "%s(%r, %r, %r)" % (self.__class__.__name__, self.expr, self.name, self.result_var) __repr__ = __str__ # # Transformation of routine objects into code # class CodeGen(object): """Abstract class for the code generators.""" printer = None # will be set to an instance of a CodePrinter subclass def _indent_code(self, codelines): return self.printer.indent_code(codelines) def _printer_method_with_settings(self, method, settings=None, args, kwargs): settings = settings or {} ori = {k: self.printer._settings[k] for k in settings} for k, v in settings.items(): self.printer._settings[k] = v result = getattr(self.printer, method)(args, *kwargs) for k, v in ori.items(): self.printer._settings[k] = v return result def _get_symbol(self, s): """Returns the symbol as fcode prints it.""" if self.printer._settings['human']: expr_str = self.printer.doprint(s) else: constants, not_supported, expr_str = self.printer.doprint(s) if constants or not_supported: raise ValueError("Failed to print %s" % str(s)) return expr_str.strip() def __init__(self, project="project", cse=False): """Initialize a code generator. Derived classes will offer more options that affect the generated code. """ self.project = project self.cse = cse def routine(self, name, expr, argument_sequence=None, global_vars=None): """Creates an Routine object that is appropriate for this language. This implementation is appropriate for at least C/Fortran. Subclasses can override this if necessary. Here, we assume at most one return value (the l-value) which must be scalar. Additional outputs are OutputArguments (e.g., pointers on right-hand-side or pass-by-reference). Matrices are always returned via OutputArguments. If ``argument_sequence`` is None, arguments will be ordered alphabetically, but with all InputArguments first, and then OutputArgument and InOutArguments. """ if self.cse: from sympy.simplify.cse_main import cse if is_sequence(expr) and not isinstance(expr, (MatrixBase, MatrixExpr)): if not expr: raise ValueError("No expression given") for e in expr: if not e.is_Equality: raise CodeGenError("Lists of expressions must all be Equalities. {} is not.".format(e)) # create a list of right hand sides and simplify them rhs = [e.rhs for e in expr] common, simplified = cse(rhs) # pack the simplified expressions back up with their left hand sides expr = [Equality(e.lhs, rhs) for e, rhs in zip(expr, simplified)] else: rhs = [expr] if isinstance(expr, Equality): common, simplified = cse(expr.rhs) #, ignore=in_out_args) expr = Equality(expr.lhs, simplified[0]) else: common, simplified = cse(expr) expr = simplified local_vars = [Result(b,a) for a,b in common] local_symbols = set([a for a,_ in common]) local_expressions = Tuple([b for _,b in common]) else: local_expressions = Tuple() if is_sequence(expr) and not isinstance(expr, (MatrixBase, MatrixExpr)): if not expr: raise ValueError("No expression given") expressions = Tuple(expr) else: expressions = Tuple(expr) if self.cse: if {i.label for i in expressions.atoms(Idx)} != set(): raise CodeGenError("CSE and Indexed expressions do not play well together yet") else: # local variables for indexed expressions local_vars = {i.label for i in expressions.atoms(Idx)} local_symbols = local_vars # global variables global_vars = set() if global_vars is None else set(global_vars) # symbols that should be arguments symbols = (expressions.free_symbols \| local_expressions.free_symbols) - local_symbols - global_vars new_symbols = set([]) new_symbols.update(symbols) for symbol in symbols: if isinstance(symbol, Idx): new_symbols.remove(symbol) new_symbols.update(symbol.args[1].free_symbols) if isinstance(symbol, Indexed): new_symbols.remove(symbol) symbols = new_symbols # Decide whether to use output argument or return value return_val = [] output_args = [] for expr in expressions: if isinstance(expr, Equality): out_arg = expr.lhs expr = expr.rhs if isinstance(out_arg, Indexed): dims = tuple([ (S.Zero, dim - 1) for dim in out_arg.shape]) symbol = out_arg.base.label elif isinstance(out_arg, Symbol): dims = [] symbol = out_arg elif isinstance(out_arg, MatrixSymbol): dims = tuple([ (S.Zero, dim - 1) for dim in out_arg.shape]) symbol = out_arg else: raise CodeGenError("Only Indexed, Symbol, or MatrixSymbol " "can define output arguments.") if expr.has(symbol): output_args.append( InOutArgument(symbol, out_arg, expr, dimensions=dims)) else: output_args.append( OutputArgument(symbol, out_arg, expr, dimensions=dims)) # remove duplicate arguments when they are not local variables if symbol not in local_vars: # avoid duplicate arguments symbols.remove(symbol) elif isinstance(expr, (ImmutableMatrix, MatrixSlice)): # Create a "dummy" MatrixSymbol to use as the Output arg out_arg = MatrixSymbol('out_%s' % abs(hash(expr)), expr.shape) dims = tuple([(S.Zero, dim - 1) for dim in out_arg.shape]) output_args.append( OutputArgument(out_arg, out_arg, expr, dimensions=dims)) else: return_val.append(Result(expr)) arg_list = [] # setup input argument list array_symbols = {} for array in expressions.atoms(Indexed) \| local_expressions.atoms(Indexed): array_symbols[array.base.label] = array for array in expressions.atoms(MatrixSymbol) \| local_expressions.atoms(MatrixSymbol): array_symbols[array] = array for symbol in sorted(symbols, key=str): if symbol in array_symbols: dims = [] array = array_symbols[symbol] for dim in array.shape: dims.append((S.Zero, dim - 1)) metadata = {'dimensions': dims} else: metadata = {} arg_list.append(InputArgument(symbol, *metadata)) output_args.sort(key=lambda x: str(x.name)) arg_list.extend(output_args) if argument_sequence is not None: # if the user has supplied IndexedBase instances, we'll accept that new_sequence = [] for arg in argument_sequence: if isinstance(arg, IndexedBase): new_sequence.append(arg.label) else: new_sequence.append(arg) argument_sequence = new_sequence missing = [x for x in arg_list if x.name not in argument_sequence] if missing: msg = "Argument list didn't specify: {0} " msg = msg.format(", ".join([str(m.name) for m in missing])) raise CodeGenArgumentListError(msg, missing) # create redundant arguments to produce the requested sequence name_arg_dict = {x.name: x for x in arg_list} new_args = [] for symbol in argument_sequence: try: new_args.append(name_arg_dict[symbol]) except KeyError: new_args.append(InputArgument(symbol)) arg_list = new_args return Routine(name, arg_list, return_val, local_vars, global_vars) def write(self, routines, prefix, to_files=False, header=True, empty=True): """Writes all the source code files for the given routines. The generated source is returned as a list of (filename, contents) tuples, or is written to files (see below). Each filename consists of the given prefix, appended with an appropriate extension. Parameters ========== routines : list A list of Routine instances to be written prefix : string The prefix for the output files to_files : bool, optional When True, the output is written to files. Otherwise, a list of (filename, contents) tuples is returned. [default: False] header : bool, optional When True, a header comment is included on top of each source file. [default: True] empty : bool, optional When True, empty lines are included to structure the source files. [default: True] """ if to_files: for dump_fn in self.dump_fns: filename = "%s.%s" % (prefix, dump_fn.extension) with open(filename, "w") as f: dump_fn(self, routines, f, prefix, header, empty) else: result = [] for dump_fn in self.dump_fns: filename = "%s.%s" % (prefix, dump_fn.extension) contents = StringIO() dump_fn(self, routines, contents, prefix, header, empty) result.append((filename, contents.getvalue())) return result def dump_code(self, routines, f, prefix, header=True, empty=True): """Write the code by calling language specific methods. The generated file contains all the definitions of the routines in low-level code and refers to the header file if appropriate. Parameters ========== routines : list A list of Routine instances. f : file-like Where to write the file. prefix : string The filename prefix, used to refer to the proper header file. Only the basename of the prefix is used. header : bool, optional When True, a header comment is included on top of each source file. [default : True] empty : bool, optional When True, empty lines are included to structure the source files. [default : True] """ code_lines = self._preprocessor_statements(prefix) for routine in routines: if empty: code_lines.append("\n") code_lines.extend(self._get_routine_opening(routine)) code_lines.extend(self._declare_arguments(routine)) code_lines.extend(self._declare_globals(routine)) code_lines.extend(self._declare_locals(routine)) if empty: code_lines.append("\n") code_lines.extend(self._call_printer(routine)) if empty: code_lines.append("\n") code_lines.extend(self._get_routine_ending(routine)) code_lines = self._indent_code(''.join(code_lines)) if header: code_lines = ''.join(self._get_header() + [code_lines]) if code_lines: f.write(code_lines) class CodeGenError(Exception): pass class CodeGenArgumentListError(Exception): @property def missing_args(self): return self.args[1] header_comment = """Code generated with sympy %(version)s See http://www.sympy.org/ for more information. This file is part of '%(project)s' """ class CCodeGen(CodeGen): """Generator for C code. The .write() method inherited from CodeGen will output a code file and an interface file, <prefix>.c and <prefix>.h respectively. """ code_extension = "c" interface_extension = "h" standard = 'c99' def __init__(self, project="project", printer=None, preprocessor_statements=None, cse=False): super(CCodeGen, self).__init__(project=project, cse=cse) self.printer = printer or c_code_printers[self.standard.lower()]() self.preprocessor_statements = preprocessor_statements if preprocessor_statements is None: self.preprocessor_statements = ['#include <math.h>'] def _get_header(self): """Writes a common header for the generated files.""" code_lines = [] code_lines.append("/" + ""78 + '\n') tmp = header_comment % {"version": sympy_version, "project": self.project} for line in tmp.splitlines(): code_lines.append(" %s\n" % line.center(76)) code_lines.append(" " + ""78 + "/\n") return code_lines def get_prototype(self, routine): """Returns a string for the function prototype of the routine. If the routine has multiple result objects, an CodeGenError is raised. See: https://en.wikipedia.org/wiki/Function_prototype """ if len(routine.results) > 1: raise CodeGenError("C only supports a single or no return value.") elif len(routine.results) == 1: ctype = routine.results[0].get_datatype('C') else: ctype = "void" type_args = [] for arg in routine.arguments: name = self.printer.doprint(arg.name) if arg.dimensions or isinstance(arg, ResultBase): type_args.append((arg.get_datatype('C'), "%s" % name)) else: type_args.append((arg.get_datatype('C'), name)) arguments = ", ".join([ "%s %s" % t for t in type_args]) return "%s %s(%s)" % (ctype, routine.name, arguments) def _preprocessor_statements(self, prefix): code_lines = [] code_lines.append('#include "{}.h"'.format(os.path.basename(prefix))) code_lines.extend(self.preprocessor_statements) code_lines = ['{}\n'.format(l) for l in code_lines] return code_lines def _get_routine_opening(self, routine): prototype = self.get_prototype(routine) return ["%s {\n" % prototype] def _declare_arguments(self, routine): # arguments are declared in prototype return [] def _declare_globals(self, routine): # global variables are not explicitly declared within C functions return [] def _declare_locals(self, routine): # Compose a list of symbols to be dereferenced in the function # body. These are the arguments that were passed by a reference # pointer, excluding arrays. dereference = [] for arg in routine.arguments: if isinstance(arg, ResultBase) and not arg.dimensions: dereference.append(arg.name) code_lines = [] for result in routine.local_vars: # local variables that are simple symbols such as those used as indices into # for loops are defined declared elsewhere. if not isinstance(result, Result): continue if result.name != result.result_var: raise CodeGen("Result variable and name should match: {}".format(result)) assign_to = result.name t = result.get_datatype('c') if isinstance(result.expr, (MatrixBase, MatrixExpr)): dims = result.expr.shape if dims[1] != 1: raise CodeGenError("Only column vectors are supported in local variabels. Local result {} has dimensions {}".format(result, dims)) code_lines.append("{0} {1}[{2}];\n".format(t, str(assign_to), dims[0])) prefix = "" else: prefix = "const {0} ".format(t) constants, not_c, c_expr = self._printer_method_with_settings( 'doprint', dict(human=False, dereference=dereference), result.expr, assign_to=assign_to) for name, value in sorted(constants, key=str): code_lines.append("double const %s = %s;\n" % (name, value)) code_lines.append("{}{}\n".format(prefix, c_expr)) return code_lines def _call_printer(self, routine): code_lines = [] # Compose a list of symbols to be dereferenced in the function # body. These are the arguments that were passed by a reference # pointer, excluding arrays. dereference = [] for arg in routine.arguments: if isinstance(arg, ResultBase) and not arg.dimensions: dereference.append(arg.name) return_val = None for result in routine.result_variables: if isinstance(result, Result): assign_to = routine.name + "_result" t = result.get_datatype('c') code_lines.append("{0} {1};\n".format(t, str(assign_to))) return_val = assign_to else: assign_to = result.result_var try: constants, not_c, c_expr = self._printer_method_with_settings( 'doprint', dict(human=False, dereference=dereference), result.expr, assign_to=assign_to) except AssignmentError: assign_to = result.result_var code_lines.append( "%s %s;\n" % (result.get_datatype('c'), str(assign_to))) constants, not_c, c_expr = self._printer_method_with_settings( 'doprint', dict(human=False, dereference=dereference), result.expr, assign_to=assign_to) for name, value in sorted(constants, key=str): code_lines.append("double const %s = %s;\n" % (name, value)) code_lines.append("%s\n" % c_expr) if return_val: code_lines.append(" return %s;\n" % return_val) return code_lines def _get_routine_ending(self, routine): return ["}\n"] def dump_c(self, routines, f, prefix, header=True, empty=True): self.dump_code(routines, f, prefix, header, empty) dump_c.extension = code_extension dump_c.__doc__ = CodeGen.dump_code.__doc__ def dump_h(self, routines, f, prefix, header=True, empty=True): """Writes the C header file. This file contains all the function declarations. Parameters ========== routines : list A list of Routine instances. f : file-like Where to write the file. prefix : string The filename prefix, used to construct the include guards. Only the basename of the prefix is used. header : bool, optional When True, a header comment is included on top of each source file. [default : True] empty : bool, optional When True, empty lines are included to structure the source files. [default : True] """ if header: print(''.join(self._get_header()), file=f) guard_name = "%s__%s__H" % (self.project.replace( " ", "_").upper(), prefix.replace("/", "_").upper()) # include guards if empty: print(file=f) print("#ifndef %s" % guard_name, file=f) print("#define %s" % guard_name, file=f) if empty: print(file=f) # declaration of the function prototypes for routine in routines: prototype = self.get_prototype(routine) print("%s;" % prototype, file=f) # end if include guards if empty: print(file=f) print("#endif", file=f) if empty: print(file=f) dump_h.extension = interface_extension # This list of dump functions is used by CodeGen.write to know which dump # functions it has to call. dump_fns = [dump_c, dump_h] class C89CodeGen(CCodeGen): standard = 'C89' class C99CodeGen(CCodeGen): standard = 'C99' class FCodeGen(CodeGen): """Generator for Fortran 95 code The .write() method inherited from CodeGen will output a code file and an interface file, <prefix>.f90 and <prefix>.h respectively. """ code_extension = "f90" interface_extension = "h" def __init__(self, project='project', printer=None): super(FCodeGen, self).__init__(project) self.printer = printer or FCodePrinter() def _get_header(self): """Writes a common header for the generated files.""" code_lines = [] code_lines.append("!" + ""78 + '\n') tmp = header_comment % {"version": sympy_version, "project": self.project} for line in tmp.splitlines(): code_lines.append("!%s\n" % line.center(76)) code_lines.append("!" + ""78 + '\n') return code_lines def _preprocessor_statements(self, prefix): return [] def _get_routine_opening(self, routine): """Returns the opening statements of the fortran routine.""" code_list = [] if len(routine.results) > 1: raise CodeGenError( "Fortran only supports a single or no return value.") elif len(routine.results) == 1: result = routine.results[0] code_list.append(result.get_datatype('fortran')) code_list.append("function") else: code_list.append("subroutine") args = ", ".join("%s" % self._get_symbol(arg.name) for arg in routine.arguments) call_sig = "{0}({1})\n".format(routine.name, args) # Fortran 95 requires all lines be less than 132 characters, so wrap # this line before appending. call_sig = ' &\n'.join(textwrap.wrap(call_sig, width=60, break_long_words=False)) + '\n' code_list.append(call_sig) code_list = [' '.join(code_list)] code_list.append('implicit none\n') return code_list def _declare_arguments(self, routine): # argument type declarations code_list = [] array_list = [] scalar_list = [] for arg in routine.arguments: if isinstance(arg, InputArgument): typeinfo = "%s, intent(in)" % arg.get_datatype('fortran') elif isinstance(arg, InOutArgument): typeinfo = "%s, intent(inout)" % arg.get_datatype('fortran') elif isinstance(arg, OutputArgument): typeinfo = "%s, intent(out)" % arg.get_datatype('fortran') else: raise CodeGenError("Unknown Argument type: %s" % type(arg)) fprint = self._get_symbol if arg.dimensions: # fortran arrays start at 1 dimstr = ", ".join(["%s:%s" % ( fprint(dim[0] + 1), fprint(dim[1] + 1)) for dim in arg.dimensions]) typeinfo += ", dimension(%s)" % dimstr array_list.append("%s :: %s\n" % (typeinfo, fprint(arg.name))) else: scalar_list.append("%s :: %s\n" % (typeinfo, fprint(arg.name))) # scalars first, because they can be used in array declarations code_list.extend(scalar_list) code_list.extend(array_list) return code_list def _declare_globals(self, routine): # Global variables not explicitly declared within Fortran 90 functions. # Note: a future F77 mode may need to generate "common" blocks. return [] def _declare_locals(self, routine): code_list = [] for var in sorted(routine.local_vars, key=str): typeinfo = get_default_datatype(var) code_list.append("%s :: %s\n" % ( typeinfo.fname, self._get_symbol(var))) return code_list def _get_routine_ending(self, routine): """Returns the closing statements of the fortran routine.""" if len(routine.results) == 1: return ["end function\n"] else: return ["end subroutine\n"] def get_interface(self, routine): """Returns a string for the function interface. The routine should have a single result object, which can be None. If the routine has multiple result objects, a CodeGenError is raised. See: https://en.wikipedia.org/wiki/Function_prototype """ prototype = [ "interface\n" ] prototype.extend(self._get_routine_opening(routine)) prototype.extend(self._declare_arguments(routine)) prototype.extend(self._get_routine_ending(routine)) prototype.append("end interface\n") return "".join(prototype) def _call_printer(self, routine): declarations = [] code_lines = [] for result in routine.result_variables: if isinstance(result, Result): assign_to = routine.name elif isinstance(result, (OutputArgument, InOutArgument)): assign_to = result.result_var constants, not_fortran, f_expr = self._printer_method_with_settings( 'doprint', dict(human=False, source_format='free', standard=95), result.expr, assign_to=assign_to) for obj, v in sorted(constants, key=str): t = get_default_datatype(obj) declarations.append( "%s, parameter :: %s = %s\n" % (t.fname, obj, v)) for obj in sorted(not_fortran, key=str): t = get_default_datatype(obj) if isinstance(obj, Function): name = obj.func else: name = obj declarations.append("%s :: %s\n" % (t.fname, name)) code_lines.append("%s\n" % f_expr) return declarations + code_lines def _indent_code(self, codelines): return self._printer_method_with_settings( 'indent_code', dict(human=False, source_format='free'), codelines) def dump_f95(self, routines, f, prefix, header=True, empty=True): # check that symbols are unique with ignorecase for r in routines: lowercase = {str(x).lower() for x in r.variables} orig_case = {str(x) for x in r.variables} if len(lowercase) < len(orig_case): raise CodeGenError("Fortran ignores case. Got symbols: %s" % (", ".join([str(var) for var in r.variables]))) self.dump_code(routines, f, prefix, header, empty) dump_f95.extension = code_extension dump_f95.__doc__ = CodeGen.dump_code.__doc__ def dump_h(self, routines, f, prefix, header=True, empty=True): """Writes the interface to a header file. This file contains all the function declarations. Parameters ========== routines : list A list of Routine instances. f : file-like Where to write the file. prefix : string The filename prefix. header : bool, optional When True, a header comment is included on top of each source file. [default : True] empty : bool, optional When True, empty lines are included to structure the source files. [default : True] """ if header: print(''.join(self._get_header()), file=f) if empty: print(file=f) # declaration of the function prototypes for routine in routines: prototype = self.get_interface(routine) f.write(prototype) if empty: print(file=f) dump_h.extension = interface_extension # This list of dump functions is used by CodeGen.write to know which dump # functions it has to call. dump_fns = [dump_f95, dump_h] class JuliaCodeGen(CodeGen): """Generator for Julia code. The .write() method inherited from CodeGen will output a code file <prefix>.jl. """ code_extension = "jl" def __init__(self, project='project', printer=None): super(JuliaCodeGen, self).__init__(project) self.printer = printer or JuliaCodePrinter() def routine(self, name, expr, argument_sequence, global_vars): """Specialized Routine creation for Julia.""" if is_sequence(expr) and not isinstance(expr, (MatrixBase, MatrixExpr)): if not expr: raise ValueError("No expression given") expressions = Tuple(expr) else: expressions = Tuple(expr) # local variables local_vars = {i.label for i in expressions.atoms(Idx)} # global variables global_vars = set() if global_vars is None else set(global_vars) # symbols that should be arguments old_symbols = expressions.free_symbols - local_vars - global_vars symbols = set([]) for s in old_symbols: if isinstance(s, Idx): symbols.update(s.args[1].free_symbols) elif not isinstance(s, Indexed): symbols.add(s) # Julia supports multiple return values return_vals = [] output_args = [] for (i, expr) in enumerate(expressions): if isinstance(expr, Equality): out_arg = expr.lhs expr = expr.rhs symbol = out_arg if isinstance(out_arg, Indexed): dims = tuple([ (S.One, dim) for dim in out_arg.shape]) symbol = out_arg.base.label output_args.append(InOutArgument(symbol, out_arg, expr, dimensions=dims)) if not isinstance(out_arg, (Indexed, Symbol, MatrixSymbol)): raise CodeGenError("Only Indexed, Symbol, or MatrixSymbol " "can define output arguments.") return_vals.append(Result(expr, name=symbol, result_var=out_arg)) if not expr.has(symbol): # this is a pure output: remove from the symbols list, so # it doesn't become an input. symbols.remove(symbol) else: # we have no name for this output return_vals.append(Result(expr, name='out%d' % (i+1))) # setup input argument list output_args.sort(key=lambda x: str(x.name)) arg_list = list(output_args) array_symbols = {} for array in expressions.atoms(Indexed): array_symbols[array.base.label] = array for array in expressions.atoms(MatrixSymbol): array_symbols[array] = array for symbol in sorted(symbols, key=str): arg_list.append(InputArgument(symbol)) if argument_sequence is not None: # if the user has supplied IndexedBase instances, we'll accept that new_sequence = [] for arg in argument_sequence: if isinstance(arg, IndexedBase): new_sequence.append(arg.label) else: new_sequence.append(arg) argument_sequence = new_sequence missing = [x for x in arg_list if x.name not in argument_sequence] if missing: msg = "Argument list didn't specify: {0} " msg = msg.format(", ".join([str(m.name) for m in missing])) raise CodeGenArgumentListError(msg, missing) # create redundant arguments to produce the requested sequence name_arg_dict = {x.name: x for x in arg_list} new_args = [] for symbol in argument_sequence: try: new_args.append(name_arg_dict[symbol]) except KeyError: new_args.append(InputArgument(symbol)) arg_list = new_args return Routine(name, arg_list, return_vals, local_vars, global_vars) def _get_header(self): """Writes a common header for the generated files.""" code_lines = [] tmp = header_comment % {"version": sympy_version, "project": self.project} for line in tmp.splitlines(): if line == '': code_lines.append("#\n") else: code_lines.append("# %s\n" % line) return code_lines def _preprocessor_statements(self, prefix): return [] def _get_routine_opening(self, routine): """Returns the opening statements of the routine.""" code_list = [] code_list.append("function ") # Inputs args = [] for i, arg in enumerate(routine.arguments): if isinstance(arg, OutputArgument): raise CodeGenError("Julia: invalid argument of type %s" % str(type(arg))) if isinstance(arg, (InputArgument, InOutArgument)): args.append("%s" % self._get_symbol(arg.name)) args = ", ".join(args) code_list.append("%s(%s)\n" % (routine.name, args)) code_list = [ "".join(code_list) ] return code_list def _declare_arguments(self, routine): return [] def _declare_globals(self, routine): return [] def _declare_locals(self, routine): return [] def _get_routine_ending(self, routine): outs = [] for result in routine.results: if isinstance(result, Result): # Note: name not result_var; want `y` not `y[i]` for Indexed s = self._get_symbol(result.name) else: raise CodeGenError("unexpected object in Routine results") outs.append(s) return ["return " + ", ".join(outs) + "\nend\n"] def _call_printer(self, routine): declarations = [] code_lines = [] for i, result in enumerate(routine.results): if isinstance(result, Result): assign_to = result.result_var else: raise CodeGenError("unexpected object in Routine results") constants, not_supported, jl_expr = self._printer_method_with_settings( 'doprint', dict(human=False), result.expr, assign_to=assign_to) for obj, v in sorted(constants, key=str): declarations.append( "%s = %s\n" % (obj, v)) for obj in sorted(not_supported, key=str): if isinstance(obj, Function): name = obj.func else: name = obj declarations.append( "# unsupported: %s\n" % (name)) code_lines.append("%s\n" % (jl_expr)) return declarations + code_lines def _indent_code(self, codelines): # Note that indenting seems to happen twice, first # statement-by-statement by JuliaPrinter then again here. p = JuliaCodePrinter({'human': False}) return p.indent_code(codelines) def dump_jl(self, routines, f, prefix, header=True, empty=True): self.dump_code(routines, f, prefix, header, empty) dump_jl.extension = code_extension dump_jl.__doc__ = CodeGen.dump_code.__doc__ # This list of dump functions is used by CodeGen.write to know which dump # functions it has to call. dump_fns = [dump_jl] class OctaveCodeGen(CodeGen): """Generator for Octave code. The .write() method inherited from CodeGen will output a code file <prefix>.m. Octave .m files usually contain one function. That function name should match the filename (``prefix``). If you pass multiple ``name_expr`` pairs, the latter ones are presumed to be private functions accessed by the primary function. You should only pass inputs to ``argument_sequence``: outputs are ordered according to their order in ``name_expr``. """ code_extension = "m" def __init__(self, project='project', printer=None): super(OctaveCodeGen, self).__init__(project) self.printer = printer or OctaveCodePrinter() def routine(self, name, expr, argument_sequence, global_vars): """Specialized Routine creation for Octave.""" # FIXME: this is probably general enough for other high-level # languages, perhaps its the C/Fortran one that is specialized! if is_sequence(expr) and not isinstance(expr, (MatrixBase, MatrixExpr)): if not expr: raise ValueError("No expression given") expressions = Tuple(expr) else: expressions = Tuple(expr) # local variables local_vars = {i.label for i in expressions.atoms(Idx)} # global variables global_vars = set() if global_vars is None else set(global_vars) # symbols that should be arguments old_symbols = expressions.free_symbols - local_vars - global_vars symbols = set([]) for s in old_symbols: if isinstance(s, Idx): symbols.update(s.args[1].free_symbols) elif not isinstance(s, Indexed): symbols.add(s) # Octave supports multiple return values return_vals = [] for (i, expr) in enumerate(expressions): if isinstance(expr, Equality): out_arg = expr.lhs expr = expr.rhs symbol = out_arg if isinstance(out_arg, Indexed): symbol = out_arg.base.label if not isinstance(out_arg, (Indexed, Symbol, MatrixSymbol)): raise CodeGenError("Only Indexed, Symbol, or MatrixSymbol " "can define output arguments.") return_vals.append(Result(expr, name=symbol, result_var=out_arg)) if not expr.has(symbol): # this is a pure output: remove from the symbols list, so # it doesn't become an input. symbols.remove(symbol) else: # we have no name for this output return_vals.append(Result(expr, name='out%d' % (i+1))) # setup input argument list arg_list = [] array_symbols = {} for array in expressions.atoms(Indexed): array_symbols[array.base.label] = array for array in expressions.atoms(MatrixSymbol): array_symbols[array] = array for symbol in sorted(symbols, key=str): arg_list.append(InputArgument(symbol)) if argument_sequence is not None: # if the user has supplied IndexedBase instances, we'll accept that new_sequence = [] for arg in argument_sequence: if isinstance(arg, IndexedBase): new_sequence.append(arg.label) else: new_sequence.append(arg) argument_sequence = new_sequence missing = [x for x in arg_list if x.name not in argument_sequence] if missing: msg = "Argument list didn't specify: {0} " msg = msg.format(", ".join([str(m.name) for m in missing])) raise CodeGenArgumentListError(msg, missing) # create redundant arguments to produce the requested sequence name_arg_dict = {x.name: x for x in arg_list} new_args = [] for symbol in argument_sequence: try: new_args.append(name_arg_dict[symbol]) except KeyError: new_args.append(InputArgument(symbol)) arg_list = new_args return Routine(name, arg_list, return_vals, local_vars, global_vars) def _get_header(self): """Writes a common header for the generated files.""" code_lines = [] tmp = header_comment % {"version": sympy_version, "project": self.project} for line in tmp.splitlines(): if line == '': code_lines.append("%\n") else: code_lines.append("%% %s\n" % line) return code_lines def _preprocessor_statements(self, prefix): return [] def _get_routine_opening(self, routine): """Returns the opening statements of the routine.""" code_list = [] code_list.append("function ") # Outputs outs = [] for i, result in enumerate(routine.results): if isinstance(result, Result): # Note: name not result_var; want `y` not `y(i)` for Indexed s = self._get_symbol(result.name) else: raise CodeGenError("unexpected object in Routine results") outs.append(s) if len(outs) > 1: code_list.append("[" + (", ".join(outs)) + "]") else: code_list.append("".join(outs)) code_list.append(" = ") # Inputs args = [] for i, arg in enumerate(routine.arguments): if isinstance(arg, (OutputArgument, InOutArgument)): raise CodeGenError("Octave: invalid argument of type %s" % str(type(arg))) if isinstance(arg, InputArgument): args.append("%s" % self._get_symbol(arg.name)) args = ", ".join(args) code_list.append("%s(%s)\n" % (routine.name, args)) code_list = [ "".join(code_list) ] return code_list def _declare_arguments(self, routine): return [] def _declare_globals(self, routine): if not routine.global_vars: return [] s = " ".join(sorted([self._get_symbol(g) for g in routine.global_vars])) return ["global " + s + "\n"] def _declare_locals(self, routine): return [] def _get_routine_ending(self, routine): return ["end\n"] def _call_printer(self, routine): declarations = [] code_lines = [] for i, result in enumerate(routine.results): if isinstance(result, Result): assign_to = result.result_var else: raise CodeGenError("unexpected object in Routine results") constants, not_supported, oct_expr = self._printer_method_with_settings( 'doprint', dict(human=False), result.expr, assign_to=assign_to) for obj, v in sorted(constants, key=str): declarations.append( " %s = %s; %% constant\n" % (obj, v)) for obj in sorted(not_supported, key=str): if isinstance(obj, Function): name = obj.func else: name = obj declarations.append( " %% unsupported: %s\n" % (name)) code_lines.append("%s\n" % (oct_expr)) return declarations + code_lines def _indent_code(self, codelines): return self._printer_method_with_settings( 'indent_code', dict(human=False), codelines) def dump_m(self, routines, f, prefix, header=True, empty=True, inline=True): # Note used to call self.dump_code() but we need more control for header code_lines = self._preprocessor_statements(prefix) for i, routine in enumerate(routines): if i > 0: if empty: code_lines.append("\n") code_lines.extend(self._get_routine_opening(routine)) if i == 0: if routine.name != prefix: raise ValueError('Octave function name should match prefix') if header: code_lines.append("%" + prefix.upper() + " Autogenerated by sympy\n") code_lines.append(''.join(self._get_header())) code_lines.extend(self._declare_arguments(routine)) code_lines.extend(self._declare_globals(routine)) code_lines.extend(self._declare_locals(routine)) if empty: code_lines.append("\n") code_lines.extend(self._call_printer(routine)) if empty: code_lines.append("\n") code_lines.extend(self._get_routine_ending(routine)) code_lines = self._indent_code(''.join(code_lines)) if code_lines: f.write(code_lines) dump_m.extension = code_extension dump_m.__doc__ = CodeGen.dump_code.__doc__ # This list of dump functions is used by CodeGen.write to know which dump # functions it has to call. dump_fns = [dump_m] class RustCodeGen(CodeGen): """Generator for Rust code. The .write() method inherited from CodeGen will output a code file <prefix>.rs """ code_extension = "rs" def __init__(self, project="project", printer=None): super(RustCodeGen, self).__init__(project=project) self.printer = printer or RustCodePrinter() def routine(self, name, expr, argument_sequence, global_vars): """Specialized Routine creation for Rust.""" if is_sequence(expr) and not isinstance(expr, (MatrixBase, MatrixExpr)): if not expr: raise ValueError("No expression given") expressions = Tuple(expr) else: expressions = Tuple(expr) # local variables local_vars = set([i.label for i in expressions.atoms(Idx)]) # global variables global_vars = set() if global_vars is None else set(global_vars) # symbols that should be arguments symbols = expressions.free_symbols - local_vars - global_vars - expressions.atoms(Indexed) # Rust supports multiple return values return_vals = [] output_args = [] for (i, expr) in enumerate(expressions): if isinstance(expr, Equality): out_arg = expr.lhs expr = expr.rhs symbol = out_arg if isinstance(out_arg, Indexed): dims = tuple([ (S.One, dim) for dim in out_arg.shape]) symbol = out_arg.base.label output_args.append(InOutArgument(symbol, out_arg, expr, dimensions=dims)) if not isinstance(out_arg, (Indexed, Symbol, MatrixSymbol)): raise CodeGenError("Only Indexed, Symbol, or MatrixSymbol " "can define output arguments.") return_vals.append(Result(expr, name=symbol, result_var=out_arg)) if not expr.has(symbol): # this is a pure output: remove from the symbols list, so # it doesn't become an input. symbols.remove(symbol) else: # we have no name for this output return_vals.append(Result(expr, name='out%d' % (i+1))) # setup input argument list output_args.sort(key=lambda x: str(x.name)) arg_list = list(output_args) array_symbols = {} for array in expressions.atoms(Indexed): array_symbols[array.base.label] = array for array in expressions.atoms(MatrixSymbol): array_symbols[array] = array for symbol in sorted(symbols, key=str): arg_list.append(InputArgument(symbol)) if argument_sequence is not None: # if the user has supplied IndexedBase instances, we'll accept that new_sequence = [] for arg in argument_sequence: if isinstance(arg, IndexedBase): new_sequence.append(arg.label) else: new_sequence.append(arg) argument_sequence = new_sequence missing = [x for x in arg_list if x.name not in argument_sequence] if missing: msg = "Argument list didn't specify: {0} " msg = msg.format(", ".join([str(m.name) for m in missing])) raise CodeGenArgumentListError(msg, missing) # create redundant arguments to produce the requested sequence name_arg_dict = dict([(x.name, x) for x in arg_list]) new_args = [] for symbol in argument_sequence: try: new_args.append(name_arg_dict[symbol]) except KeyError: new_args.append(InputArgument(symbol)) arg_list = new_args return Routine(name, arg_list, return_vals, local_vars, global_vars) def _get_header(self): """Writes a common header for the generated files.""" code_lines = [] code_lines.append("/\n") tmp = header_comment % {"version": sympy_version, "project": self.project} for line in tmp.splitlines(): code_lines.append((" %s" % line.center(76)).rstrip() + "\n") code_lines.append(" /\n") return code_lines def get_prototype(self, routine): """Returns a string for the function prototype of the routine. If the routine has multiple result objects, an CodeGenError is raised. See: https://en.wikipedia.org/wiki/Function_prototype """ results = [i.get_datatype('Rust') for i in routine.results] if len(results) == 1: rstype = " -> " + results[0] elif len(routine.results) > 1: rstype = " -> (" + ", ".join(results) + ")" else: rstype = "" type_args = [] for arg in routine.arguments: name = self.printer.doprint(arg.name) if arg.dimensions or isinstance(arg, ResultBase): type_args.append(("%s" % name, arg.get_datatype('Rust'))) else: type_args.append((name, arg.get_datatype('Rust'))) arguments = ", ".join([ "%s: %s" % t for t in type_args]) return "fn %s(%s)%s" % (routine.name, arguments, rstype) def _preprocessor_statements(self, prefix): code_lines = [] # code_lines.append("use std::f64::consts::;\n") return code_lines def _get_routine_opening(self, routine): prototype = self.get_prototype(routine) return ["%s {\n" % prototype] def _declare_arguments(self, routine): # arguments are declared in prototype return [] def _declare_globals(self, routine): # global variables are not explicitly declared within C functions return [] def _declare_locals(self, routine): # loop variables are declared in loop statement return [] def _call_printer(self, routine): code_lines = [] declarations = [] returns = [] # Compose a list of symbols to be dereferenced in the function # body. These are the arguments that were passed by a reference # pointer, excluding arrays. dereference = [] for arg in routine.arguments: if isinstance(arg, ResultBase) and not arg.dimensions: dereference.append(arg.name) for i, result in enumerate(routine.results): if isinstance(result, Result): assign_to = result.result_var returns.append(str(result.result_var)) else: raise CodeGenError("unexpected object in Routine results") constants, not_supported, rs_expr = self._printer_method_with_settings( 'doprint', dict(human=False), result.expr, assign_to=assign_to) for name, value in sorted(constants, key=str): declarations.append("const %s: f64 = %s;\n" % (name, value)) for obj in sorted(not_supported, key=str): if isinstance(obj, Function): name = obj.func else: name = obj declarations.append("// unsupported: %s\n" % (name)) code_lines.append("let %s\n" % rs_expr); if len(returns) > 1: returns = ['(' + ', '.join(returns) + ')'] returns.append('\n') return declarations + code_lines + returns def _get_routine_ending(self, routine): return ["}\n"] def dump_rs(self, routines, f, prefix, header=True, empty=True): self.dump_code(routines, f, prefix, header, empty) dump_rs.extension = code_extension dump_rs.__doc__ = CodeGen.dump_code.__doc__ # This list of dump functions is used by CodeGen.write to know which dump # functions it has to call. dump_fns = [dump_rs] def get_code_generator(language, project=None, standard=None, printer = None): if language == 'C': if standard is None: pass elif standard.lower() == 'c89': language = 'C89' elif standard.lower() == 'c99': language = 'C99' CodeGenClass = {"C": CCodeGen, "C89": C89CodeGen, "C99": C99CodeGen, "F95": FCodeGen, "JULIA": JuliaCodeGen, "OCTAVE": OctaveCodeGen, "RUST": RustCodeGen}.get(language.upper()) if CodeGenClass is None: raise ValueError("Language '%s' is not supported." % language) return CodeGenClass(project, printer) # # Friendly functions # def codegen(name_expr, language=None, prefix=None, project="project", to_files=False, header=True, empty=True, argument_sequence=None, global_vars=None, standard=None, code_gen=None, printer = None): """Generate source code for expressions in a given language. Parameters ========== name_expr : tuple, or list of tuples A single (name, expression) tuple or a list of (name, expression) tuples. Each tuple corresponds to a routine. If the expression is an equality (an instance of class Equality) the left hand side is considered an output argument. If expression is an iterable, then the routine will have multiple outputs. language : string, A string that indicates the source code language. This is case insensitive. Currently, 'C', 'F95' and 'Octave' are supported. 'Octave' generates code compatible with both Octave and Matlab. prefix : string, optional A prefix for the names of the files that contain the source code. Language-dependent suffixes will be appended. If omitted, the name of the first name_expr tuple is used. project : string, optional A project name, used for making unique preprocessor instructions. [default: "project"] to_files : bool, optional When True, the code will be written to one or more files with the given prefix, otherwise strings with the names and contents of these files are returned. [default: False] header : bool, optional When True, a header is written on top of each source file. [default: True] empty : bool, optional When True, empty lines are used to structure the code. [default: True] argument_sequence : iterable, optional Sequence of arguments for the routine in a preferred order. A CodeGenError is raised if required arguments are missing. Redundant arguments are used without warning. If omitted, arguments will be ordered alphabetically, but with all input arguments first, and then output or in-out arguments. global_vars : iterable, optional Sequence of global variables used by the routine. Variables listed here will not show up as function arguments. standard : string code_gen : CodeGen instance An instance of a CodeGen subclass. Overrides ``language``. Examples ======== >>> from sympy.utilities.codegen import codegen >>> from sympy.abc import x, y, z >>> [(c_name, c_code), (h_name, c_header)] = codegen( ... ("f", x+yz), "C89", "test", header=False, empty=False) >>> print(c_name) test.c >>> print(c_code) #include "test.h" #include <math.h> double f(double x, double y, double z) { double f_result; f_result = x + yz; return f_result; } <BLANKLINE> >>> print(h_name) test.h >>> print(c_header) #ifndef PROJECT__TEST__H #define PROJECT__TEST__H double f(double x, double y, double z); #endif <BLANKLINE> Another example using Equality objects to give named outputs. Here the filename (prefix) is taken from the first (name, expr) pair. >>> from sympy.abc import f, g >>> from sympy import Eq >>> [(c_name, c_code), (h_name, c_header)] = codegen( ... [("myfcn", x + y), ("fcn2", [Eq(f, 2x), Eq(g, y)])], ... "C99", header=False, empty=False) >>> print(c_name) myfcn.c >>> print(c_code) #include "myfcn.h" #include <math.h> double myfcn(double x, double y) { double myfcn_result; myfcn_result = x + y; return myfcn_result; } void fcn2(double x, double y, double f, double g) { (f) = 2x; (g) = y; } <BLANKLINE> If the generated function(s) will be part of a larger project where various global variables have been defined, the 'global_vars' option can be used to remove the specified variables from the function signature >>> from sympy.utilities.codegen import codegen >>> from sympy.abc import x, y, z >>> [(f_name, f_code), header] = codegen( ... ("f", x+yz), "F95", header=False, empty=False, ... argument_sequence=(x, y), global_vars=(z,)) >>> print(f_code) REAL8 function f(x, y) implicit none REAL8, intent(in) :: x REAL8, intent(in) :: y f = x + yz end function <BLANKLINE> """ # Initialize the code generator. if language is None: if code_gen is None: raise ValueError("Need either language or code_gen") else: if code_gen is not None: raise ValueError("You cannot specify both language and code_gen.") code_gen = get_code_generator(language, project, standard, printer) if isinstance(name_expr[0], string_types): # single tuple is given, turn it into a singleton list with a tuple. name_expr = [name_expr] if prefix is None: prefix = name_expr[0][0] # Construct Routines appropriate for this code_gen from (name, expr) pairs. routines = [] for name, expr in name_expr: routines.append(code_gen.routine(name, expr, argument_sequence, global_vars)) # Write the code. return code_gen.write(routines, prefix, to_files, header, empty) def make_routine(name, expr, argument_sequence=None, global_vars=None, language="F95"): """A factory that makes an appropriate Routine from an expression. Parameters ========== name : string The name of this routine in the generated code. expr : expression or list/tuple of expressions A SymPy expression that the Routine instance will represent. If given a list or tuple of expressions, the routine will be considered to have multiple return values and/or output arguments. argument_sequence : list or tuple, optional List arguments for the routine in a preferred order. If omitted, the results are language dependent, for example, alphabetical order or in the same order as the given expressions. global_vars : iterable, optional Sequence of global variables used by the routine. Variables listed here will not show up as function arguments. language : string, optional Specify a target language. The Routine itself should be language-agnostic but the precise way one is created, error checking, etc depend on the language. [default: "F95"]. A decision about whether to use output arguments or return values is made depending on both the language and the particular mathematical expressions. For an expression of type Equality, the left hand side is typically made into an OutputArgument (or perhaps an InOutArgument if appropriate). Otherwise, typically, the calculated expression is made a return values of the routine. Examples ======== >>> from sympy.utilities.codegen import make_routine >>> from sympy.abc import x, y, f, g >>> from sympy import Eq >>> r = make_routine('test', [Eq(f, 2x), Eq(g, x + y)]) >>> [arg.result_var for arg in r.results] [] >>> [arg.name for arg in r.arguments] [x, y, f, g] >>> [arg.name for arg in r.result_variables] [f, g] >>> r.local_vars set() Another more complicated example with a mixture of specified and automatically-assigned names. Also has Matrix output. >>> from sympy import Matrix >>> r = make_routine('fcn', [xy, Eq(f, 1), Eq(g, x + g), Matrix([[x, 2]])]) >>> [arg.result_var for arg in r.results] # doctest: +SKIP [result_5397460570204848505] >>> [arg.expr for arg in r.results] [xy] >>> [arg.name for arg in r.arguments] # doctest: +SKIP [x, y, f, g, out_8598435338387848786] We can examine the various arguments more closely: >>> from sympy.utilities.codegen import (InputArgument, OutputArgument, ... InOutArgument) >>> [a.name for a in r.arguments if isinstance(a, InputArgument)] [x, y] >>> [a.name for a in r.arguments if isinstance(a, OutputArgument)] # doctest: +SKIP [f, out_8598435338387848786] >>> [a.expr for a in r.arguments if isinstance(a, OutputArgument)] [1, Matrix([[x, 2]])] >>> [a.name for a in r.arguments if isinstance(a, InOutArgument)] [g] >>> [a.expr for a in r.arguments if isinstance(a, InOutArgument)] [g + x] """ # initialize a new code generator code_gen = get_code_generator(language) return code_gen.routine(name, expr, argument_sequence, global_vars)
ec0a315c77a569a13d0a7b0b877a989cc22eb594c8caf82173b78cc30cc23b20	"""Module for compiling codegen output, and wrap the binary for use in python. .. note:: To use the autowrap module it must first be imported >>> from sympy.utilities.autowrap import autowrap This module provides a common interface for different external backends, such as f2py, fwrap, Cython, SWIG(?) etc. (Currently only f2py and Cython are implemented) The goal is to provide access to compiled binaries of acceptable performance with a one-button user interface, i.e. >>> from sympy.abc import x,y >>> expr = ((x - y)*(25)).expand() >>> binary_callable = autowrap(expr) >>> binary_callable(1, 2) -1.0 The callable returned from autowrap() is a binary python function, not a SymPy object. If it is desired to use the compiled function in symbolic expressions, it is better to use binary_function() which returns a SymPy Function object. The binary callable is attached as the _imp_ attribute and invoked when a numerical evaluation is requested with evalf(), or with lambdify(). >>> from sympy.utilities.autowrap import binary_function >>> f = binary_function('f', expr) >>> 2f(x, y) + y y + 2f(x, y) >>> (2f(x, y) + y).evalf(2, subs={x: 1, y:2}) 0.e-110 The idea is that a SymPy user will primarily be interested in working with mathematical expressions, and should not have to learn details about wrapping tools in order to evaluate expressions numerically, even if they are computationally expensive. When is this useful? 1) For computations on large arrays, Python iterations may be too slow, and depending on the mathematical expression, it may be difficult to exploit the advanced index operations provided by NumPy. 2) For really long expressions that will be called repeatedly, the compiled binary should be significantly faster than SymPy's .evalf() 3) If you are generating code with the codegen utility in order to use it in another project, the automatic python wrappers let you test the binaries immediately from within SymPy. 4) To create customized ufuncs for use with numpy arrays. See ufuncify. When is this module NOT the best approach? 1) If you are really concerned about speed or memory optimizations, you will probably get better results by working directly with the wrapper tools and the low level code. However, the files generated by this utility may provide a useful starting point and reference code. Temporary files will be left intact if you supply the keyword tempdir="path/to/files/". 2) If the array computation can be handled easily by numpy, and you don't need the binaries for another project. """ from __future__ import print_function, division import sys import os import shutil import tempfile from subprocess import STDOUT, CalledProcessError, check_output from string import Template from warnings import warn from sympy.core.cache import cacheit from sympy.core.compatibility import range, iterable from sympy.core.function import Lambda from sympy.core.relational import Eq from sympy.core.symbol import Dummy, Symbol from sympy.tensor.indexed import Idx, IndexedBase from sympy.utilities.codegen import (make_routine, get_code_generator, OutputArgument, InOutArgument, InputArgument, CodeGenArgumentListError, Result, ResultBase, C99CodeGen) from sympy.utilities.lambdify import implemented_function from sympy.utilities.decorator import doctest_depends_on _doctest_depends_on = {'exe': ('f2py', 'gfortran', 'gcc'), 'modules': ('numpy',)} class CodeWrapError(Exception): pass class CodeWrapper(object): """Base Class for code wrappers""" _filename = "wrapped_code" _module_basename = "wrapper_module" _module_counter = 0 @property def filename(self): return "%s_%s" % (self._filename, CodeWrapper._module_counter) @property def module_name(self): return "%s_%s" % (self._module_basename, CodeWrapper._module_counter) def __init__(self, generator, filepath=None, flags=[], verbose=False): """ generator -- the code generator to use """ self.generator = generator self.filepath = filepath self.flags = flags self.quiet = not verbose @property def include_header(self): return bool(self.filepath) @property def include_empty(self): return bool(self.filepath) def _generate_code(self, main_routine, routines): routines.append(main_routine) self.generator.write( routines, self.filename, True, self.include_header, self.include_empty) def wrap_code(self, routine, helpers=[]): if self.filepath: workdir = os.path.abspath(self.filepath) else: workdir = tempfile.mkdtemp("_sympy_compile") if not os.access(workdir, os.F_OK): os.mkdir(workdir) oldwork = os.getcwd() os.chdir(workdir) try: sys.path.append(workdir) self._generate_code(routine, helpers) self._prepare_files(routine) self._process_files(routine) mod = __import__(self.module_name) finally: sys.path.remove(workdir) CodeWrapper._module_counter += 1 os.chdir(oldwork) if not self.filepath: try: shutil.rmtree(workdir) except OSError: # Could be some issues on Windows pass return self._get_wrapped_function(mod, routine.name) def _process_files(self, routine): command = self.command command.extend(self.flags) try: retoutput = check_output(command, stderr=STDOUT) except CalledProcessError as e: raise CodeWrapError( "Error while executing command: %s. Command output is:\n%s" % ( " ".join(command), e.output.decode('utf-8'))) if not self.quiet: print(retoutput) class DummyWrapper(CodeWrapper): """Class used for testing independent of backends """ template = """# dummy module for testing of SymPy def %(name)s(): return "%(expr)s" %(name)s.args = "%(args)s" %(name)s.returns = "%(retvals)s" """ def _prepare_files(self, routine): return def _generate_code(self, routine, helpers): with open('%s.py' % self.module_name, 'w') as f: printed = ", ".join( [str(res.expr) for res in routine.result_variables]) # convert OutputArguments to return value like f2py args = filter(lambda x: not isinstance( x, OutputArgument), routine.arguments) retvals = [] for val in routine.result_variables: if isinstance(val, Result): retvals.append('nameless') else: retvals.append(val.result_var) print(DummyWrapper.template % { 'name': routine.name, 'expr': printed, 'args': ", ".join([str(a.name) for a in args]), 'retvals': ", ".join([str(val) for val in retvals]) }, end="", file=f) def _process_files(self, routine): return @classmethod def _get_wrapped_function(cls, mod, name): return getattr(mod, name) class CythonCodeWrapper(CodeWrapper): """Wrapper that uses Cython""" setup_template = """\ try: from setuptools import setup from setuptools import Extension except ImportError: from distutils.core import setup from distutils.extension import Extension from Cython.Build import cythonize cy_opts = {cythonize_options} {np_import} ext_mods = [Extension( {ext_args}, include_dirs={include_dirs}, library_dirs={library_dirs}, libraries={libraries}, extra_compile_args={extra_compile_args}, extra_link_args={extra_link_args} )] setup(ext_modules=cythonize(ext_mods, *cy_opts)) """ pyx_imports = ( "import numpy as np\n" "cimport numpy as np\n\n") pyx_header = ( "cdef extern from '{header_file}.h':\n" " {prototype}\n\n") pyx_func = ( "def {name}_c({arg_string}):\n" "\n" "{declarations}" "{body}") std_compile_flag = '-std=c99' def __init__(self, args, *kwargs): """Instantiates a Cython code wrapper. The following optional parameters get passed to ``distutils.Extension`` for building the Python extension module. Read its documentation to learn more. Parameters ========== include_dirs : [list of strings] A list of directories to search for C/C++ header files (in Unix form for portability). library_dirs : [list of strings] A list of directories to search for C/C++ libraries at link time. libraries : [list of strings] A list of library names (not filenames or paths) to link against. extra_compile_args : [list of strings] Any extra platform- and compiler-specific information to use when compiling the source files in 'sources'. For platforms and compilers where "command line" makes sense, this is typically a list of command-line arguments, but for other platforms it could be anything. Note that the attribute ``std_compile_flag`` will be appended to this list. extra_link_args : [list of strings] Any extra platform- and compiler-specific information to use when linking object files together to create the extension (or to create a new static Python interpreter). Similar interpretation as for 'extra_compile_args'. cythonize_options : [dictionary] Keyword arguments passed on to cythonize. """ self._include_dirs = kwargs.pop('include_dirs', []) self._library_dirs = kwargs.pop('library_dirs', []) self._libraries = kwargs.pop('libraries', []) self._extra_compile_args = kwargs.pop('extra_compile_args', []) self._extra_compile_args.append(self.std_compile_flag) self._extra_link_args = kwargs.pop('extra_link_args', []) self._cythonize_options = kwargs.pop('cythonize_options', {}) self._need_numpy = False super(CythonCodeWrapper, self).__init__(args, *kwargs) @property def command(self): command = [sys.executable, "setup.py", "build_ext", "--inplace"] return command def _prepare_files(self, routine, build_dir=os.curdir): # NOTE : build_dir is used for testing purposes. pyxfilename = self.module_name + '.pyx' codefilename = "%s.%s" % (self.filename, self.generator.code_extension) # pyx with open(os.path.join(build_dir, pyxfilename), 'w') as f: self.dump_pyx([routine], f, self.filename) # setup.py ext_args = [repr(self.module_name), repr([pyxfilename, codefilename])] if self._need_numpy: np_import = 'import numpy as np\n' self._include_dirs.append('np.get_include()') else: np_import = '' with open(os.path.join(build_dir, 'setup.py'), 'w') as f: includes = str(self._include_dirs).replace("'np.get_include()'", 'np.get_include()') f.write(self.setup_template.format( ext_args=", ".join(ext_args), np_import=np_import, include_dirs=includes, library_dirs=self._library_dirs, libraries=self._libraries, extra_compile_args=self._extra_compile_args, extra_link_args=self._extra_link_args, cythonize_options=self._cythonize_options )) @classmethod def _get_wrapped_function(cls, mod, name): return getattr(mod, name + '_c') def dump_pyx(self, routines, f, prefix): """Write a Cython file with python wrappers This file contains all the definitions of the routines in c code and refers to the header file. Arguments --------- routines List of Routine instances f File-like object to write the file to prefix The filename prefix, used to refer to the proper header file. Only the basename of the prefix is used. """ headers = [] functions = [] for routine in routines: prototype = self.generator.get_prototype(routine) # C Function Header Import headers.append(self.pyx_header.format(header_file=prefix, prototype=prototype)) # Partition the C function arguments into categories py_rets, py_args, py_loc, py_inf = self._partition_args(routine.arguments) # Function prototype name = routine.name arg_string = ", ".join(self._prototype_arg(arg) for arg in py_args) # Local Declarations local_decs = [] for arg, val in py_inf.items(): proto = self._prototype_arg(arg) mat, ind = val local_decs.append(" cdef {0} = {1}.shape[{2}]".format(proto, mat, ind)) local_decs.extend([" cdef {0}".format(self._declare_arg(a)) for a in py_loc]) declarations = "\n".join(local_decs) if declarations: declarations = declarations + "\n" # Function Body args_c = ", ".join([self._call_arg(a) for a in routine.arguments]) rets = ", ".join([str(r.name) for r in py_rets]) if routine.results: body = ' return %s(%s)' % (routine.name, args_c) if rets: body = body + ', ' + rets else: body = ' %s(%s)\n' % (routine.name, args_c) body = body + ' return ' + rets functions.append(self.pyx_func.format(name=name, arg_string=arg_string, declarations=declarations, body=body)) # Write text to file if self._need_numpy: # Only import numpy if required f.write(self.pyx_imports) f.write('\n'.join(headers)) f.write('\n'.join(functions)) def _partition_args(self, args): """Group function arguments into categories.""" py_args = [] py_returns = [] py_locals = [] py_inferred = {} for arg in args: if isinstance(arg, OutputArgument): py_returns.append(arg) py_locals.append(arg) elif isinstance(arg, InOutArgument): py_returns.append(arg) py_args.append(arg) else: py_args.append(arg) # Find arguments that are array dimensions. These can be inferred # locally in the Cython code. if isinstance(arg, (InputArgument, InOutArgument)) and arg.dimensions: dims = [d[1] + 1 for d in arg.dimensions] sym_dims = [(i, d) for (i, d) in enumerate(dims) if isinstance(d, Symbol)] for (i, d) in sym_dims: py_inferred[d] = (arg.name, i) for arg in args: if arg.name in py_inferred: py_inferred[arg] = py_inferred.pop(arg.name) # Filter inferred arguments from py_args py_args = [a for a in py_args if a not in py_inferred] return py_returns, py_args, py_locals, py_inferred def _prototype_arg(self, arg): mat_dec = "np.ndarray[{mtype}, ndim={ndim}] {name}" np_types = {'double': 'np.double_t', 'int': 'np.int_t'} t = arg.get_datatype('c') if arg.dimensions: self._need_numpy = True ndim = len(arg.dimensions) mtype = np_types[t] return mat_dec.format(mtype=mtype, ndim=ndim, name=arg.name) else: return "%s %s" % (t, str(arg.name)) def _declare_arg(self, arg): proto = self._prototype_arg(arg) if arg.dimensions: shape = '(' + ','.join(str(i[1] + 1) for i in arg.dimensions) + ')' return proto + " = np.empty({shape})".format(shape=shape) else: return proto + " = 0" def _call_arg(self, arg): if arg.dimensions: t = arg.get_datatype('c') return "<{0}> {1}.data".format(t, arg.name) elif isinstance(arg, ResultBase): return "&{0}".format(arg.name) else: return str(arg.name) class F2PyCodeWrapper(CodeWrapper): """Wrapper that uses f2py""" def __init__(self, args, kwargs): ext_keys = ['include_dirs', 'library_dirs', 'libraries', 'extra_compile_args', 'extra_link_args'] msg = ('The compilation option kwarg {} is not supported with the f2py ' 'backend.') for k in ext_keys: if k in kwargs.keys(): warn(msg.format(k)) kwargs.pop(k, None) super(F2PyCodeWrapper, self).__init__(args, kwargs) @property def command(self): filename = self.filename + '.' + self.generator.code_extension args = ['-c', '-m', self.module_name, filename] command = [sys.executable, "-c", "import numpy.f2py as f2py2e;f2py2e.main()"]+args return command def _prepare_files(self, routine): pass @classmethod def _get_wrapped_function(cls, mod, name): return getattr(mod, name) # Here we define a lookup of backends -> tuples of languages. For now, each # tuple is of length 1, but if a backend supports more than one language, # the most preferable language is listed first. _lang_lookup = {'CYTHON': ('C99', 'C89', 'C'), 'F2PY': ('F95',), 'NUMPY': ('C99', 'C89', 'C'), 'DUMMY': ('F95',)} # Dummy here just for testing def _infer_language(backend): """For a given backend, return the top choice of language""" langs = _lang_lookup.get(backend.upper(), False) if not langs: raise ValueError("Unrecognized backend: " + backend) return langs[0] def _validate_backend_language(backend, language): """Throws error if backend and language are incompatible""" langs = _lang_lookup.get(backend.upper(), False) if not langs: raise ValueError("Unrecognized backend: " + backend) if language.upper() not in langs: raise ValueError(("Backend {0} and language {1} are " "incompatible").format(backend, language)) @cacheit @doctest_depends_on(exe=('f2py', 'gfortran'), modules=('numpy',)) def autowrap(expr, language=None, backend='f2py', tempdir=None, args=None, flags=None, verbose=False, helpers=None, code_gen=None, kwargs): """Generates python callable binaries based on the math expression. Parameters ========== expr The SymPy expression that should be wrapped as a binary routine. language : string, optional If supplied, (options: 'C' or 'F95'), specifies the language of the generated code. If ``None`` [default], the language is inferred based upon the specified backend. backend : string, optional Backend used to wrap the generated code. Either 'f2py' [default], or 'cython'. tempdir : string, optional Path to directory for temporary files. If this argument is supplied, the generated code and the wrapper input files are left intact in the specified path. args : iterable, optional An ordered iterable of symbols. Specifies the argument sequence for the function. flags : iterable, optional Additional option flags that will be passed to the backend. verbose : bool, optional If True, autowrap will not mute the command line backends. This can be helpful for debugging. helpers : 3-tuple or iterable of 3-tuples, optional Used to define auxiliary expressions needed for the main expr. If the main expression needs to call a specialized function it should be passed in via ``helpers``. Autowrap will then make sure that the compiled main expression can link to the helper routine. Items should be 3-tuples with (<function_name>, <sympy_expression>, <argument_tuple>). It is mandatory to supply an argument sequence to helper routines. code_gen : CodeGen instance An instance of a CodeGen subclass. Overrides ``language``. include_dirs : [string] A list of directories to search for C/C++ header files (in Unix form for portability). library_dirs : [string] A list of directories to search for C/C++ libraries at link time. libraries : [string] A list of library names (not filenames or paths) to link against. extra_compile_args : [string] Any extra platform- and compiler-specific information to use when compiling the source files in 'sources'. For platforms and compilers where "command line" makes sense, this is typically a list of command-line arguments, but for other platforms it could be anything. extra_link_args : [string] Any extra platform- and compiler-specific information to use when linking object files together to create the extension (or to create a new static Python interpreter). Similar interpretation as for 'extra_compile_args'. Examples ======== >>> from sympy.abc import x, y, z >>> from sympy.utilities.autowrap import autowrap >>> expr = ((x - y + z)(13)).expand() >>> binary_func = autowrap(expr) >>> binary_func(1, 4, 2) -1.0 """ if language: if not isinstance(language, type): _validate_backend_language(backend, language) else: language = _infer_language(backend) # two cases 1) helpers is an iterable of 3-tuples and 2) helpers is a # 3-tuple if iterable(helpers) and len(helpers) != 0 and iterable(helpers[0]): helpers = helpers if helpers else () else: helpers = [helpers] if helpers else () args = list(args) if iterable(args, exclude=set) else args if code_gen is None: code_gen = get_code_generator(language, "autowrap") CodeWrapperClass = { 'F2PY': F2PyCodeWrapper, 'CYTHON': CythonCodeWrapper, 'DUMMY': DummyWrapper }[backend.upper()] code_wrapper = CodeWrapperClass(code_gen, tempdir, flags if flags else (), verbose, kwargs) helps = [] for name_h, expr_h, args_h in helpers: helps.append(code_gen.routine(name_h, expr_h, args_h)) for name_h, expr_h, args_h in helpers: if expr.has(expr_h): name_h = binary_function(name_h, expr_h, backend='dummy') expr = expr.subs(expr_h, name_h(args_h)) try: routine = code_gen.routine('autofunc', expr, args) except CodeGenArgumentListError as e: # if all missing arguments are for pure output, we simply attach them # at the end and try again, because the wrappers will silently convert # them to return values anyway. new_args = [] for missing in e.missing_args: if not isinstance(missing, OutputArgument): raise new_args.append(missing.name) routine = code_gen.routine('autofunc', expr, args + new_args) return code_wrapper.wrap_code(routine, helpers=helps) @doctest_depends_on(exe=('f2py', 'gfortran'), modules=('numpy',)) def binary_function(symfunc, expr, kwargs): """Returns a sympy function with expr as binary implementation This is a convenience function that automates the steps needed to autowrap the SymPy expression and attaching it to a Function object with implemented_function(). Parameters ========== symfunc : sympy Function The function to bind the callable to. expr : sympy Expression The expression used to generate the function. kwargs : dict Any kwargs accepted by autowrap. Examples ======== >>> from sympy.abc import x, y >>> from sympy.utilities.autowrap import binary_function >>> expr = ((x - y)(25)).expand() >>> f = binary_function('f', expr) >>> type(f) <class 'sympy.core.function.UndefinedFunction'> >>> 2f(x, y) 2f(x, y) >>> f(x, y).evalf(2, subs={x: 1, y: 2}) -1.0 """ binary = autowrap(expr, kwargs) return implemented_function(symfunc, binary) ################################################################# # UFUNCIFY # ################################################################# _ufunc_top = Template("""\ #include "Python.h" #include "math.h" #include "numpy/ndarraytypes.h" #include "numpy/ufuncobject.h" #include "numpy/halffloat.h" #include ${include_file} static PyMethodDef ${module}Methods[] = { {NULL, NULL, 0, NULL} };""") _ufunc_outcalls = Template("((double )out${outnum}) = ${funcname}(${call_args});") _ufunc_body = Template("""\ static void ${funcname}_ufunc(char args, npy_intp dimensions, npy_intp* steps, void* data) { npy_intp i; npy_intp n = dimensions[0]; ${declare_args} ${declare_steps} for (i = 0; i < n; i++) { ${outcalls} ${step_increments} } } PyUFuncGenericFunction ${funcname}_funcs[1] = {&${funcname}_ufunc}; static char ${funcname}_types[${n_types}] = ${types} static void ${funcname}_data[1] = {NULL};""") _ufunc_bottom = Template("""\ #if PY_VERSION_HEX >= 0x03000000 static struct PyModuleDef moduledef = { PyModuleDef_HEAD_INIT, "${module}", NULL, -1, ${module}Methods, NULL, NULL, NULL, NULL }; PyMODINIT_FUNC PyInit_${module}(void) { PyObject m, d; ${function_creation} m = PyModule_Create(&moduledef); if (!m) { return NULL; } import_array(); import_umath(); d = PyModule_GetDict(m); ${ufunc_init} return m; } #else PyMODINIT_FUNC init${module}(void) { PyObject m, d; ${function_creation} m = Py_InitModule("${module}", ${module}Methods); if (m == NULL) { return; } import_array(); import_umath(); d = PyModule_GetDict(m); ${ufunc_init} } #endif\ """) _ufunc_init_form = Template("""\ ufunc${ind} = PyUFunc_FromFuncAndData(${funcname}_funcs, ${funcname}_data, ${funcname}_types, 1, ${n_in}, ${n_out}, PyUFunc_None, "${module}", ${docstring}, 0); PyDict_SetItemString(d, "${funcname}", ufunc${ind}); Py_DECREF(ufunc${ind});""") _ufunc_setup = Template("""\ def configuration(parent_package='', top_path=None): import numpy from numpy.distutils.misc_util import Configuration config = Configuration('', parent_package, top_path) config.add_extension('${module}', sources=['${module}.c', '${filename}.c']) return config if __name__ == "__main__": from numpy.distutils.core import setup setup(configuration=configuration)""") class UfuncifyCodeWrapper(CodeWrapper): """Wrapper for Ufuncify""" def __init__(self, args, *kwargs): ext_keys = ['include_dirs', 'library_dirs', 'libraries', 'extra_compile_args', 'extra_link_args'] msg = ('The compilation option kwarg {} is not supported with the numpy' ' backend.') for k in ext_keys: if k in kwargs.keys(): warn(msg.format(k)) kwargs.pop(k, None) super(UfuncifyCodeWrapper, self).__init__(args, *kwargs) @property def command(self): command = [sys.executable, "setup.py", "build_ext", "--inplace"] return command def wrap_code(self, routines, helpers=None): # This routine overrides CodeWrapper because we can't assume funcname == routines[0].name # Therefore we have to break the CodeWrapper private API. # There isn't an obvious way to extend multi-expr support to # the other autowrap backends, so we limit this change to ufuncify. helpers = helpers if helpers is not None else [] # We just need a consistent name funcname = 'wrapped_' + str(id(routines) + id(helpers)) workdir = self.filepath or tempfile.mkdtemp("_sympy_compile") if not os.access(workdir, os.F_OK): os.mkdir(workdir) oldwork = os.getcwd() os.chdir(workdir) try: sys.path.append(workdir) self._generate_code(routines, helpers) self._prepare_files(routines, funcname) self._process_files(routines) mod = __import__(self.module_name) finally: sys.path.remove(workdir) CodeWrapper._module_counter += 1 os.chdir(oldwork) if not self.filepath: try: shutil.rmtree(workdir) except OSError: # Could be some issues on Windows pass return self._get_wrapped_function(mod, funcname) def _generate_code(self, main_routines, helper_routines): all_routines = main_routines + helper_routines self.generator.write( all_routines, self.filename, True, self.include_header, self.include_empty) def _prepare_files(self, routines, funcname): # C codefilename = self.module_name + '.c' with open(codefilename, 'w') as f: self.dump_c(routines, f, self.filename, funcname=funcname) # setup.py with open('setup.py', 'w') as f: self.dump_setup(f) @classmethod def _get_wrapped_function(cls, mod, name): return getattr(mod, name) def dump_setup(self, f): setup = _ufunc_setup.substitute(module=self.module_name, filename=self.filename) f.write(setup) def dump_c(self, routines, f, prefix, funcname=None): """Write a C file with python wrappers This file contains all the definitions of the routines in c code. Arguments --------- routines List of Routine instances f File-like object to write the file to prefix The filename prefix, used to name the imported module. funcname Name of the main function to be returned. """ if (funcname is None) and (len(routines) == 1): funcname = routines[0].name elif funcname is None: msg = 'funcname must be specified for multiple output routines' raise ValueError(msg) functions = [] function_creation = [] ufunc_init = [] module = self.module_name include_file = "\"{0}.h\"".format(prefix) top = _ufunc_top.substitute(include_file=include_file, module=module) name = funcname # Partition the C function arguments into categories # Here we assume all routines accept the same arguments r_index = 0 py_in, _ = self._partition_args(routines[0].arguments) n_in = len(py_in) n_out = len(routines) # Declare Args form = "char {0}{1} = args[{2}];" arg_decs = [form.format('in', i, i) for i in range(n_in)] arg_decs.extend([form.format('out', i, i+n_in) for i in range(n_out)]) declare_args = '\n '.join(arg_decs) # Declare Steps form = "npy_intp {0}{1}_step = steps[{2}];" step_decs = [form.format('in', i, i) for i in range(n_in)] step_decs.extend([form.format('out', i, i+n_in) for i in range(n_out)]) declare_steps = '\n '.join(step_decs) # Call Args form = "(double )in{0}" call_args = ', '.join([form.format(a) for a in range(n_in)]) # Step Increments form = "{0}{1} += {0}{1}_step;" step_incs = [form.format('in', i) for i in range(n_in)] step_incs.extend([form.format('out', i, i) for i in range(n_out)]) step_increments = '\n '.join(step_incs) # Types n_types = n_in + n_out types = "{" + ', '.join(["NPY_DOUBLE"]n_types) + "};" # Docstring docstring = '"Created in SymPy with Ufuncify"' # Function Creation function_creation.append("PyObject ufunc{0};".format(r_index)) # Ufunc initialization init_form = _ufunc_init_form.substitute(module=module, funcname=name, docstring=docstring, n_in=n_in, n_out=n_out, ind=r_index) ufunc_init.append(init_form) outcalls = [_ufunc_outcalls.substitute( outnum=i, call_args=call_args, funcname=routines[i].name) for i in range(n_out)] body = _ufunc_body.substitute(module=module, funcname=name, declare_args=declare_args, declare_steps=declare_steps, call_args=call_args, step_increments=step_increments, n_types=n_types, types=types, outcalls='\n '.join(outcalls)) functions.append(body) body = '\n\n'.join(functions) ufunc_init = '\n '.join(ufunc_init) function_creation = '\n '.join(function_creation) bottom = _ufunc_bottom.substitute(module=module, ufunc_init=ufunc_init, function_creation=function_creation) text = [top, body, bottom] f.write('\n\n'.join(text)) def _partition_args(self, args): """Group function arguments into categories.""" py_in = [] py_out = [] for arg in args: if isinstance(arg, OutputArgument): py_out.append(arg) elif isinstance(arg, InOutArgument): raise ValueError("Ufuncify doesn't support InOutArguments") else: py_in.append(arg) return py_in, py_out @cacheit @doctest_depends_on(exe=('f2py', 'gfortran', 'gcc'), modules=('numpy',)) def ufuncify(args, expr, language=None, backend='numpy', tempdir=None, flags=None, verbose=False, helpers=None, kwargs): """Generates a binary function that supports broadcasting on numpy arrays. Parameters ========== args : iterable Either a Symbol or an iterable of symbols. Specifies the argument sequence for the function. expr A SymPy expression that defines the element wise operation. language : string, optional If supplied, (options: 'C' or 'F95'), specifies the language of the generated code. If ``None`` [default], the language is inferred based upon the specified backend. backend : string, optional Backend used to wrap the generated code. Either 'numpy' [default], 'cython', or 'f2py'. tempdir : string, optional Path to directory for temporary files. If this argument is supplied, the generated code and the wrapper input files are left intact in the specified path. flags : iterable, optional Additional option flags that will be passed to the backend. verbose : bool, optional If True, autowrap will not mute the command line backends. This can be helpful for debugging. helpers : iterable, optional Used to define auxiliary expressions needed for the main expr. If the main expression needs to call a specialized function it should be put in the ``helpers`` iterable. Autowrap will then make sure that the compiled main expression can link to the helper routine. Items should be tuples with (<funtion_name>, <sympy_expression>, <arguments>). It is mandatory to supply an argument sequence to helper routines. kwargs : dict These kwargs will be passed to autowrap if the `f2py` or `cython` backend is used and ignored if the `numpy` backend is used. Notes ===== The default backend ('numpy') will create actual instances of ``numpy.ufunc``. These support ndimensional broadcasting, and implicit type conversion. Use of the other backends will result in a "ufunc-like" function, which requires equal length 1-dimensional arrays for all arguments, and will not perform any type conversions. References ========== .. [1] http://docs.scipy.org/doc/numpy/reference/ufuncs.html Examples ======== >>> from sympy.utilities.autowrap import ufuncify >>> from sympy.abc import x, y >>> import numpy as np >>> f = ufuncify((x, y), y + x2) >>> type(f) <class 'numpy.ufunc'> >>> f([1, 2, 3], 2) array([ 3., 6., 11.]) >>> f(np.arange(5), 3) array([ 3., 4., 7., 12., 19.]) For the 'f2py' and 'cython' backends, inputs are required to be equal length 1-dimensional arrays. The 'f2py' backend will perform type conversion, but the Cython backend will error if the inputs are not of the expected type. >>> f_fortran = ufuncify((x, y), y + x2, backend='f2py') >>> f_fortran(1, 2) array([ 3.]) >>> f_fortran(np.array([1, 2, 3]), np.array([1.0, 2.0, 3.0])) array([ 2., 6., 12.]) >>> f_cython = ufuncify((x, y), y + x2, backend='Cython') >>> f_cython(1, 2) # doctest: +ELLIPSIS Traceback (most recent call last): ... TypeError: Argument '_x' has incorrect type (expected numpy.ndarray, got int) >>> f_cython(np.array([1.0]), np.array([2.0])) array([ 3.]) """ if isinstance(args, Symbol): args = (args,) else: args = tuple(args) if language: _validate_backend_language(backend, language) else: language = _infer_language(backend) helpers = helpers if helpers else () flags = flags if flags else () if backend.upper() == 'NUMPY': # maxargs is set by numpy compile-time constant NPY_MAXARGS # If a future version of numpy modifies or removes this restriction # this variable should be changed or removed maxargs = 32 helps = [] for name, expr, args in helpers: helps.append(make_routine(name, expr, args)) code_wrapper = UfuncifyCodeWrapper(C99CodeGen("ufuncify"), tempdir, flags, verbose) if not isinstance(expr, (list, tuple)): expr = [expr] if len(expr) == 0: raise ValueError('Expression iterable has zero length') if (len(expr) + len(args)) > maxargs: msg = ('Cannot create ufunc with more than {0} total arguments: ' 'got {1} in, {2} out') raise ValueError(msg.format(maxargs, len(args), len(expr))) routines = [make_routine('autofunc{}'.format(idx), exprx, args) for idx, exprx in enumerate(expr)] return code_wrapper.wrap_code(routines, helpers=helps) else: # Dummies are used for all added expressions to prevent name clashes # within the original expression. y = IndexedBase(Dummy('y')) m = Dummy('m', integer=True) i = Idx(Dummy('i', integer=True), m) f_dummy = Dummy('f') f = implemented_function('%s_%d' % (f_dummy.name, f_dummy.dummy_index), Lambda(args, expr)) # For each of the args create an indexed version. indexed_args = [IndexedBase(Dummy(str(a))) for a in args] # Order the arguments (out, args, dim) args = [y] + indexed_args + [m] args_with_indices = [a[i] for a in indexed_args] return autowrap(Eq(y[i], f(args_with_indices)), language, backend, tempdir, args, flags, verbose, helpers, *kwargs)
42c1a320f4d2ffeaa8947177b760507f513fa84a723043ce82f55474c9d5095a	""" This module adds several functions for interactive source code inspection. """ from __future__ import print_function, division from sympy.core.decorators import deprecated import inspect @deprecated(useinstead="?? in IPython/Jupyter or inspect.getsource", issue=14905, deprecated_since_version="1.3") def source(object): """ Prints the source code of a given object. """ print('In file: %s' % inspect.getsourcefile(object)) print(inspect.getsource(object)) def get_class(lookup_view): """ Convert a string version of a class name to the object. For example, get_class('sympy.core.Basic') will return class Basic located in module sympy.core """ if isinstance(lookup_view, str): mod_name, func_name = get_mod_func(lookup_view) if func_name != '': lookup_view = getattr( __import__(mod_name, {}, {}, ['*']), func_name) if not callable(lookup_view): raise AttributeError( "'%s.%s' is not a callable." % (mod_name, func_name)) return lookup_view def get_mod_func(callback): """ splits the string path to a class into a string path to the module and the name of the class. Examples ======== >>> from sympy.utilities.source import get_mod_func >>> get_mod_func('sympy.core.basic.Basic') ('sympy.core.basic', 'Basic') """ dot = callback.rfind('.') if dot == -1: return callback, '' return callback[:dot], callback[dot + 1:]
55b765a419a55133582cbc376e8c79ab512cf9e475b6b99773ff763d02d94164	""" This module provides convenient functions to transform sympy expressions to lambda functions which can be used to calculate numerical values very fast. """ from __future__ import print_function, division import inspect import keyword import re import textwrap import linecache from sympy.core.compatibility import (exec_, is_sequence, iterable, NotIterable, string_types, range, builtins, PY3) from sympy.utilities.decorator import doctest_depends_on __doctest_requires__ = {('lambdify',): ['numpy', 'tensorflow']} # Default namespaces, letting us define translations that can't be defined # by simple variable maps, like I => 1j MATH_DEFAULT = {} MPMATH_DEFAULT = {} NUMPY_DEFAULT = {"I": 1j} SCIPY_DEFAULT = {"I": 1j} TENSORFLOW_DEFAULT = {} SYMPY_DEFAULT = {} NUMEXPR_DEFAULT = {} # These are the namespaces the lambda functions will use. # These are separate from the names above because they are modified # throughout this file, whereas the defaults should remain unmodified. MATH = MATH_DEFAULT.copy() MPMATH = MPMATH_DEFAULT.copy() NUMPY = NUMPY_DEFAULT.copy() SCIPY = SCIPY_DEFAULT.copy() TENSORFLOW = TENSORFLOW_DEFAULT.copy() SYMPY = SYMPY_DEFAULT.copy() NUMEXPR = NUMEXPR_DEFAULT.copy() # Mappings between sympy and other modules function names. MATH_TRANSLATIONS = { "ceiling": "ceil", "E": "e", "ln": "log", } MPMATH_TRANSLATIONS = { "Abs": "fabs", "elliptic_k": "ellipk", "elliptic_f": "ellipf", "elliptic_e": "ellipe", "elliptic_pi": "ellippi", "ceiling": "ceil", "chebyshevt": "chebyt", "chebyshevu": "chebyu", "E": "e", "I": "j", "ln": "log", #"lowergamma":"lower_gamma", "oo": "inf", #"uppergamma":"upper_gamma", "LambertW": "lambertw", "MutableDenseMatrix": "matrix", "ImmutableDenseMatrix": "matrix", "conjugate": "conj", "dirichlet_eta": "altzeta", "Ei": "ei", "Shi": "shi", "Chi": "chi", "Si": "si", "Ci": "ci", "RisingFactorial": "rf", "FallingFactorial": "ff", } NUMPY_TRANSLATIONS = {} SCIPY_TRANSLATIONS = {} TENSORFLOW_TRANSLATIONS = { "Abs": "abs", "ceiling": "ceil", "im": "imag", "ln": "log", "Mod": "mod", "conjugate": "conj", "re": "real", } NUMEXPR_TRANSLATIONS = {} # Available modules: MODULES = { "math": (MATH, MATH_DEFAULT, MATH_TRANSLATIONS, ("from math import ",)), "mpmath": (MPMATH, MPMATH_DEFAULT, MPMATH_TRANSLATIONS, ("from mpmath import ",)), "numpy": (NUMPY, NUMPY_DEFAULT, NUMPY_TRANSLATIONS, ("import numpy; from numpy import ; from numpy.linalg import ",)), "scipy": (SCIPY, SCIPY_DEFAULT, SCIPY_TRANSLATIONS, ("import numpy; import scipy; from scipy import ; from scipy.special import ",)), "tensorflow": (TENSORFLOW, TENSORFLOW_DEFAULT, TENSORFLOW_TRANSLATIONS, ("import_module('tensorflow')",)), "sympy": (SYMPY, SYMPY_DEFAULT, {}, ( "from sympy.functions import ", "from sympy.matrices import ", "from sympy import Integral, pi, oo, nan, zoo, E, I",)), "numexpr" : (NUMEXPR, NUMEXPR_DEFAULT, NUMEXPR_TRANSLATIONS, ("import_module('numexpr')", )), } def _import(module, reload=False): """ Creates a global translation dictionary for module. The argument module has to be one of the following strings: "math", "mpmath", "numpy", "sympy", "tensorflow". These dictionaries map names of python functions to their equivalent in other modules. """ # Required despite static analysis claiming it is not used from sympy.external import import_module try: namespace, namespace_default, translations, import_commands = MODULES[ module] except KeyError: raise NameError( "'%s' module can't be used for lambdification" % module) # Clear namespace or exit if namespace != namespace_default: # The namespace was already generated, don't do it again if not forced. if reload: namespace.clear() namespace.update(namespace_default) else: return for import_command in import_commands: if import_command.startswith('import_module'): module = eval(import_command) if module is not None: namespace.update(module.__dict__) continue else: try: exec_(import_command, {}, namespace) continue except ImportError: pass raise ImportError( "can't import '%s' with '%s' command" % (module, import_command)) # Add translated names to namespace for sympyname, translation in translations.items(): namespace[sympyname] = namespace[translation] # For computing the modulus of a sympy expression we use the builtin abs # function, instead of the previously used fabs function for all # translation modules. This is because the fabs function in the math # module does not accept complex valued arguments. (see issue 9474). The # only exception, where we don't use the builtin abs function is the # mpmath translation module, because mpmath.fabs returns mpf objects in # contrast to abs(). if 'Abs' not in namespace: namespace['Abs'] = abs # Used for dynamically generated filenames that are inserted into the # linecache. _lambdify_generated_counter = 1 @doctest_depends_on(modules=('numpy')) def lambdify(args, expr, modules=None, printer=None, use_imps=True, dummify=False): """ Returns an anonymous function for fast calculation of numerical values. If not specified differently by the user, ``modules`` defaults to ``["scipy", "numpy"]`` if SciPy is installed, ``["numpy"]`` if only NumPy is installed, and ``["math", "mpmath", "sympy"]`` if neither is installed. That is, SymPy functions are replaced as far as possible by either ``scipy`` or ``numpy`` functions if available, and Python's standard library ``math``, or ``mpmath`` functions otherwise. To change this behavior, the "modules" argument can be used. It accepts: - the strings "math", "mpmath", "numpy", "numexpr", "scipy", "sympy", "tensorflow" - any modules (e.g. math) - dictionaries that map names of sympy functions to arbitrary functions - lists that contain a mix of the arguments above, with higher priority given to entries appearing first. .. warning:: Note that this function uses ``eval``, and thus shouldn't be used on unsanitized input. Arguments in the provided expression that are not valid Python identifiers are substitued with dummy symbols. This allows for applied functions (e.g. f(t)) to be supplied as arguments. Call the function with dummify=True to replace all arguments with dummy symbols (if `args` is not a string) - for example, to ensure that the arguments do not redefine any built-in names. For functions involving large array calculations, numexpr can provide a significant speedup over numpy. Please note that the available functions for numexpr are more limited than numpy but can be expanded with implemented_function and user defined subclasses of Function. If specified, numexpr may be the only option in modules. The official list of numexpr functions can be found at: https://github.com/pydata/numexpr#supported-functions In previous releases ``lambdify`` replaced ``Matrix`` with ``numpy.matrix`` by default. As of release 1.0 ``numpy.array`` is the default. To get the old default behavior you must pass in ``[{'ImmutableDenseMatrix': numpy.matrix}, 'numpy']`` to the ``modules`` kwarg. >>> from sympy import lambdify, Matrix >>> from sympy.abc import x, y >>> import numpy >>> array2mat = [{'ImmutableDenseMatrix': numpy.matrix}, 'numpy'] >>> f = lambdify((x, y), Matrix([x, y]), modules=array2mat) >>> f(1, 2) [[1] [2]] Usage ===== (1) Use one of the provided modules: >>> from sympy import sin, tan, gamma >>> from sympy.abc import x, y >>> f = lambdify(x, sin(x), "math") Attention: Functions that are not in the math module will throw a name error when the function definition is evaluated! So this would be better: >>> f = lambdify(x, sin(x)gamma(x), ("math", "mpmath", "sympy")) (2) Use some other module: >>> import numpy >>> f = lambdify((x,y), tan(xy), numpy) Attention: There are naming differences between numpy and sympy. So if you simply take the numpy module, e.g. sympy.atan will not be translated to numpy.arctan. Use the modified module instead by passing the string "numpy": >>> f = lambdify((x,y), tan(xy), "numpy") >>> f(1, 2) -2.18503986326 >>> from numpy import array >>> f(array([1, 2, 3]), array([2, 3, 5])) [-2.18503986 -0.29100619 -0.8559934 ] In the above examples, the generated functions can accept scalar values or numpy arrays as arguments. However, in some cases the generated function relies on the input being a numpy array: >>> from sympy import Piecewise >>> from sympy.utilities.pytest import ignore_warnings >>> f = lambdify(x, Piecewise((x, x <= 1), (1/x, x > 1)), "numpy") >>> with ignore_warnings(RuntimeWarning): ... f(array([-1, 0, 1, 2])) [-1. 0. 1. 0.5] >>> f(0) Traceback (most recent call last): ... ZeroDivisionError: division by zero In such cases, the input should be wrapped in a numpy array: >>> with ignore_warnings(RuntimeWarning): ... float(f(array([0]))) 0.0 Or if numpy functionality is not required another module can be used: >>> f = lambdify(x, Piecewise((x, x <= 1), (1/x, x > 1)), "math") >>> f(0) 0 (3) Use a dictionary defining custom functions: >>> def my_cool_function(x): return 'sin(%s) is cool' % x >>> myfuncs = {"sin" : my_cool_function} >>> f = lambdify(x, sin(x), myfuncs); f(1) 'sin(1) is cool' Examples ======== >>> from sympy.utilities.lambdify import implemented_function >>> from sympy import sqrt, sin, Matrix >>> from sympy import Function >>> from sympy.abc import w, x, y, z >>> f = lambdify(x, x2) >>> f(2) 4 >>> f = lambdify((x, y, z), [z, y, x]) >>> f(1,2,3) [3, 2, 1] >>> f = lambdify(x, sqrt(x)) >>> f(4) 2.0 >>> f = lambdify((x, y), sin(xy)*2) >>> f(0, 5) 0.0 >>> row = lambdify((x, y), Matrix((x, x + y)).T, modules='sympy') >>> row(1, 2) Matrix([[1, 3]]) Tuple arguments are handled and the lambdified function should be called with the same type of arguments as were used to create the function.: >>> f = lambdify((x, (y, z)), x + y) >>> f(1, (2, 4)) 3 A more robust way of handling this is to always work with flattened arguments: >>> from sympy.utilities.iterables import flatten >>> args = w, (x, (y, z)) >>> vals = 1, (2, (3, 4)) >>> f = lambdify(flatten(args), w + x + y + z) >>> f(flatten(vals)) 10 Functions present in `expr` can also carry their own numerical implementations, in a callable attached to the ``_imp_`` attribute. Usually you attach this using the ``implemented_function`` factory: >>> f = implemented_function(Function('f'), lambda x: x+1) >>> func = lambdify(x, f(x)) >>> func(4) 5 ``lambdify`` always prefers ``_imp_`` implementations to implementations in other namespaces, unless the ``use_imps`` input parameter is False. Usage with Tensorflow module: >>> import tensorflow as tf >>> f = Max(x, sin(x)) >>> func = lambdify(x, f, 'tensorflow') >>> result = func(tf.constant(1.0)) >>> result # a tf.Tensor representing the result of the calculation <tf.Tensor 'Maximum:0' shape=() dtype=float32> >>> sess = tf.Session() >>> sess.run(result) # compute result 1.0 >>> var = tf.Variable(1.0) >>> sess.run(tf.global_variables_initializer()) >>> sess.run(func(var)) # also works for tf.Variable and tf.Placeholder 1.0 >>> tensor = tf.constant([[1.0, 2.0], [3.0, 4.0]]) # works with any shape tensor >>> sess.run(func(tensor)) array([[ 1., 2.], [ 3., 4.]], dtype=float32) """ from sympy.core.symbol import Symbol # If the user hasn't specified any modules, use what is available. if modules is None: try: _import("scipy") except ImportError: try: _import("numpy") except ImportError: # Use either numpy (if available) or python.math where possible. # XXX: This leads to different behaviour on different systems and # might be the reason for irreproducible errors. modules = ["math", "mpmath", "sympy"] else: modules = ["numpy"] else: modules = ["scipy", "numpy"] # Get the needed namespaces. namespaces = [] # First find any function implementations if use_imps: namespaces.append(_imp_namespace(expr)) # Check for dict before iterating if isinstance(modules, (dict, str)) or not hasattr(modules, '__iter__'): namespaces.append(modules) else: # consistency check if _module_present('numexpr', modules) and len(modules) > 1: raise TypeError("numexpr must be the only item in 'modules'") namespaces += list(modules) # fill namespace with first having highest priority namespace = {} for m in namespaces[::-1]: buf = _get_namespace(m) namespace.update(buf) if hasattr(expr, "atoms"): #Try if you can extract symbols from the expression. #Move on if expr.atoms in not implemented. syms = expr.atoms(Symbol) for term in syms: namespace.update({str(term): term}) if printer is None: if _module_present('mpmath', namespaces): from sympy.printing.pycode import MpmathPrinter as Printer elif _module_present('scipy', namespaces): from sympy.printing.pycode import SciPyPrinter as Printer elif _module_present('numpy', namespaces): from sympy.printing.pycode import NumPyPrinter as Printer elif _module_present('numexpr', namespaces): from sympy.printing.lambdarepr import NumExprPrinter as Printer elif _module_present('tensorflow', namespaces): from sympy.printing.tensorflow import TensorflowPrinter as Printer elif _module_present('sympy', namespaces): from sympy.printing.pycode import SymPyPrinter as Printer else: from sympy.printing.pycode import PythonCodePrinter as Printer user_functions = {} for m in namespaces[::-1]: if isinstance(m, dict): for k in m: user_functions[k] = k printer = Printer({'fully_qualified_modules': False, 'inline': True, 'allow_unknown_functions': True, 'user_functions': user_functions}) # Get the names of the args, for creating a docstring if not iterable(args): args = (args,) names = [] # Grab the callers frame, for getting the names by inspection (if needed) callers_local_vars = inspect.currentframe().f_back.f_locals.items() for n, var in enumerate(args): if hasattr(var, 'name'): names.append(var.name) else: # It's an iterable. Try to get name by inspection of calling frame. name_list = [var_name for var_name, var_val in callers_local_vars if var_val is var] if len(name_list) == 1: names.append(name_list[0]) else: # Cannot infer name with certainty. arg_# will have to do. names.append('arg_' + str(n)) imp_mod_lines = [] for mod, keys in (getattr(printer, 'module_imports', None) or {}).items(): for k in keys: if k not in namespace: imp_mod_lines.append("from %s import %s" % (mod, k)) for ln in imp_mod_lines: exec_(ln, {}, namespace) # Provide lambda expression with builtins, and compatible implementation of range namespace.update({'builtins':builtins, 'range':range}) # Create the function definition code and execute it funcname = '_lambdifygenerated' if _module_present('tensorflow', namespaces): funcprinter = _TensorflowEvaluatorPrinter(printer, dummify) else: funcprinter = _EvaluatorPrinter(printer, dummify) funcstr = funcprinter.doprint(funcname, args, expr) funclocals = {} global _lambdify_generated_counter filename = '<lambdifygenerated-%s>' % _lambdify_generated_counter _lambdify_generated_counter += 1 c = compile(funcstr, filename, 'exec') exec_(c, namespace, funclocals) # mtime has to be None or else linecache.checkcache will remove it linecache.cache[filename] = (len(funcstr), None, funcstr.splitlines(True), filename) func = funclocals[funcname] # Apply the docstring sig = "func({0})".format(", ".join(str(i) for i in names)) sig = textwrap.fill(sig, subsequent_indent=' '8) expr_str = str(expr) if len(expr_str) > 78: expr_str = textwrap.wrap(expr_str, 75)[0] + '...' func.__doc__ = ( "Created with lambdify. Signature:\n\n" "{sig}\n\n" "Expression:\n\n" "{expr}\n\n" "Source code:\n\n" "{src}\n\n" "Imported modules:\n\n" "{imp_mods}" ).format(sig=sig, expr=expr_str, src=funcstr, imp_mods='\n'.join(imp_mod_lines)) return func def _module_present(modname, modlist): if modname in modlist: return True for m in modlist: if hasattr(m, '__name__') and m.__name__ == modname: return True return False def _get_namespace(m): """ This is used by _lambdify to parse its arguments. """ if isinstance(m, string_types): _import(m) return MODULES[m][0] elif isinstance(m, dict): return m elif hasattr(m, "__dict__"): return m.__dict__ else: raise TypeError("Argument must be either a string, dict or module but it is: %s" % m) def lambdastr(args, expr, printer=None, dummify=None): """ Returns a string that can be evaluated to a lambda function. Examples ======== >>> from sympy.abc import x, y, z >>> from sympy.utilities.lambdify import lambdastr >>> lambdastr(x, x2) 'lambda x: (x2)' >>> lambdastr((x,y,z), [z,y,x]) 'lambda x,y,z: ([z, y, x])' Although tuples may not appear as arguments to lambda in Python 3, lambdastr will create a lambda function that will unpack the original arguments so that nested arguments can be handled: >>> lambdastr((x, (y, z)), x + y) 'lambda _0,_1: (lambda x,y,z: (x + y))(_0,_1[0],_1[1])' """ # Transforming everything to strings. from sympy.matrices import DeferredVector from sympy import Dummy, sympify, Symbol, Function, flatten, Derivative, Basic if printer is not None: if inspect.isfunction(printer): lambdarepr = printer else: if inspect.isclass(printer): lambdarepr = lambda expr: printer().doprint(expr) else: lambdarepr = lambda expr: printer.doprint(expr) else: #XXX: This has to be done here because of circular imports from sympy.printing.lambdarepr import lambdarepr def sub_args(args, dummies_dict): if isinstance(args, str): return args elif isinstance(args, DeferredVector): return str(args) elif iterable(args): dummies = flatten([sub_args(a, dummies_dict) for a in args]) return ",".join(str(a) for a in dummies) else: # replace these with Dummy symbols if isinstance(args, (Function, Symbol, Derivative)): dummies = Dummy() dummies_dict.update({args : dummies}) return str(dummies) else: return str(args) def sub_expr(expr, dummies_dict): try: expr = sympify(expr).xreplace(dummies_dict) except Exception: if isinstance(expr, DeferredVector): pass elif isinstance(expr, dict): k = [sub_expr(sympify(a), dummies_dict) for a in expr.keys()] v = [sub_expr(sympify(a), dummies_dict) for a in expr.values()] expr = dict(zip(k, v)) elif isinstance(expr, tuple): expr = tuple(sub_expr(sympify(a), dummies_dict) for a in expr) elif isinstance(expr, list): expr = [sub_expr(sympify(a), dummies_dict) for a in expr] return expr # Transform args def isiter(l): return iterable(l, exclude=(str, DeferredVector, NotIterable)) def flat_indexes(iterable): n = 0 for el in iterable: if isiter(el): for ndeep in flat_indexes(el): yield (n,) + ndeep else: yield (n,) n += 1 if dummify is None: dummify = any(isinstance(a, Basic) and a.atoms(Function, Derivative) for a in ( args if isiter(args) else [args])) if isiter(args) and any(isiter(i) for i in args): dum_args = [str(Dummy(str(i))) for i in range(len(args))] indexed_args = ','.join([ dum_args[ind[0]] + ''.join(["[%s]" % k for k in ind[1:]]) for ind in flat_indexes(args)]) lstr = lambdastr(flatten(args), expr, printer=printer, dummify=dummify) return 'lambda %s: (%s)(%s)' % (','.join(dum_args), lstr, indexed_args) dummies_dict = {} if dummify: args = sub_args(args, dummies_dict) else: if isinstance(args, str): pass elif iterable(args, exclude=DeferredVector): args = ",".join(str(a) for a in args) # Transform expr if dummify: if isinstance(expr, str): pass else: expr = sub_expr(expr, dummies_dict) expr = lambdarepr(expr) return "lambda %s: (%s)" % (args, expr) class _EvaluatorPrinter(object): def __init__(self, printer=None, dummify=False): self._dummify = dummify #XXX: This has to be done here because of circular imports from sympy.printing.lambdarepr import LambdaPrinter if printer is None: printer = LambdaPrinter() if inspect.isfunction(printer): self._exprrepr = printer else: if inspect.isclass(printer): printer = printer() self._exprrepr = printer.doprint if hasattr(printer, '_print_Symbol'): symbolrepr = printer._print_Symbol if hasattr(printer, '_print_Dummy'): dummyrepr = printer._print_Dummy # Used to print the generated function arguments in a standard way self._argrepr = LambdaPrinter().doprint def doprint(self, funcname, args, expr): """Returns the function definition code as a string.""" from sympy import Dummy funcbody = [] if not iterable(args): args = [args] argstrs, expr = self._preprocess(args, expr) # Generate argument unpacking and final argument list funcargs = [] unpackings = [] for argstr in argstrs: if iterable(argstr): funcargs.append(self._argrepr(Dummy())) unpackings.extend(self._print_unpacking(argstr, funcargs[-1])) else: funcargs.append(argstr) funcsig = 'def {}({}):'.format(funcname, ', '.join(funcargs)) # Wrap input arguments before unpacking funcbody.extend(self._print_funcargwrapping(funcargs)) funcbody.extend(unpackings) funcbody.append('return ({})'.format(self._exprrepr(expr))) funclines = [funcsig] funclines.extend(' ' + line for line in funcbody) return '\n'.join(funclines) + '\n' if PY3: @classmethod def _is_safe_ident(cls, ident): return isinstance(ident, str) and ident.isidentifier() \ and not keyword.iskeyword(ident) else: _safe_ident_re = re.compile('^[a-zA-Z_][a-zA-Z0-9_]$') @classmethod def _is_safe_ident(cls, ident): return isinstance(ident, str) and cls._safe_ident_re.match(ident) \ and not (keyword.iskeyword(ident) or ident == 'None') def _preprocess(self, args, expr): """Preprocess args, expr to replace arguments that do not map to valid Python identifiers. Returns string form of args, and updated expr. """ from sympy import Dummy, Function, flatten, Derivative, ordered, Basic from sympy.matrices import DeferredVector # Args of type Dummy can cause name collisions with args # of type Symbol. Force dummify of everything in this # situation. dummify = self._dummify or any( isinstance(arg, Dummy) for arg in flatten(args)) argstrs = [None]len(args) for arg, i in reversed(list(ordered(zip(args, range(len(args)))))): if iterable(arg): s, expr = self._preprocess(arg, expr) elif isinstance(arg, DeferredVector): s = str(arg) elif isinstance(arg, Basic) and arg.is_symbol: s = self._argrepr(arg) if dummify or not self._is_safe_ident(s): dummy = Dummy() s = self._argrepr(dummy) expr = self._subexpr(expr, {arg: dummy}) elif dummify or isinstance(arg, (Function, Derivative)): dummy = Dummy() s = self._argrepr(dummy) expr = self._subexpr(expr, {arg: dummy}) else: s = str(arg) argstrs[i] = s return argstrs, expr def _subexpr(self, expr, dummies_dict): from sympy.matrices import DeferredVector from sympy import sympify try: expr = sympify(expr).xreplace(dummies_dict) except AttributeError: if isinstance(expr, DeferredVector): pass elif isinstance(expr, dict): k = [self._subexpr(sympify(a), dummies_dict) for a in expr.keys()] v = [self._subexpr(sympify(a), dummies_dict) for a in expr.values()] expr = dict(zip(k, v)) elif isinstance(expr, tuple): expr = tuple(self._subexpr(sympify(a), dummies_dict) for a in expr) elif isinstance(expr, list): expr = [self._subexpr(sympify(a), dummies_dict) for a in expr] return expr def _print_funcargwrapping(self, args): """Generate argument wrapping code. args is the argument list of the generated function (strings). Return value is a list of lines of code that will be inserted at the beginning of the function definition. """ return [] def _print_unpacking(self, unpackto, arg): """Generate argument unpacking code. arg is the function argument to be unpacked (a string), and unpackto is a list or nested lists of the variable names (strings) to unpack to. """ def unpack_lhs(lvalues): return '[{}]'.format(', '.join( unpack_lhs(val) if iterable(val) else val for val in lvalues)) return ['{} = {}'.format(unpack_lhs(unpackto), arg)] class _TensorflowEvaluatorPrinter(_EvaluatorPrinter): def _print_unpacking(self, lvalues, rvalue): """Generate argument unpacking code. This method is used when the input value is not interable, but can be indexed (see issue #14655). """ from sympy import flatten def flat_indexes(elems): n = 0 for el in elems: if iterable(el): for ndeep in flat_indexes(el): yield (n,) + ndeep else: yield (n,) n += 1 indexed = ', '.join('{}[{}]'.format(rvalue, ']['.join(map(str, ind))) for ind in flat_indexes(lvalues)) return ['[{}] = [{}]'.format(', '.join(flatten(lvalues)), indexed)] def _imp_namespace(expr, namespace=None): """ Return namespace dict with function implementations We need to search for functions in anything that can be thrown at us - that is - anything that could be passed as `expr`. Examples include sympy expressions, as well as tuples, lists and dicts that may contain sympy expressions. Parameters ---------- expr : object Something passed to lambdify, that will generate valid code from ``str(expr)``. namespace : None or mapping Namespace to fill. None results in new empty dict Returns ------- namespace : dict dict with keys of implemented function names within `expr` and corresponding values being the numerical implementation of function Examples ======== >>> from sympy.abc import x >>> from sympy.utilities.lambdify import implemented_function, _imp_namespace >>> from sympy import Function >>> f = implemented_function(Function('f'), lambda x: x+1) >>> g = implemented_function(Function('g'), lambda x: x10) >>> namespace = _imp_namespace(f(g(x))) >>> sorted(namespace.keys()) ['f', 'g'] """ # Delayed import to avoid circular imports from sympy.core.function import FunctionClass if namespace is None: namespace = {} # tuples, lists, dicts are valid expressions if is_sequence(expr): for arg in expr: _imp_namespace(arg, namespace) return namespace elif isinstance(expr, dict): for key, val in expr.items(): # functions can be in dictionary keys _imp_namespace(key, namespace) _imp_namespace(val, namespace) return namespace # sympy expressions may be Functions themselves func = getattr(expr, 'func', None) if isinstance(func, FunctionClass): imp = getattr(func, '_imp_', None) if imp is not None: name = expr.func.__name__ if name in namespace and namespace[name] != imp: raise ValueError('We found more than one ' 'implementation with name ' '"%s"' % name) namespace[name] = imp # and / or they may take Functions as arguments if hasattr(expr, 'args'): for arg in expr.args: _imp_namespace(arg, namespace) return namespace def implemented_function(symfunc, implementation): """ Add numerical ``implementation`` to function ``symfunc``. ``symfunc`` can be an ``UndefinedFunction`` instance, or a name string. In the latter case we create an ``UndefinedFunction`` instance with that name. Be aware that this is a quick workaround, not a general method to create special symbolic functions. If you want to create a symbolic function to be used by all the machinery of SymPy you should subclass the ``Function`` class. Parameters ---------- symfunc : ``str`` or ``UndefinedFunction`` instance If ``str``, then create new ``UndefinedFunction`` with this as name. If `symfunc` is an Undefined function, create a new function with the same name and the implemented function attached. implementation : callable numerical implementation to be called by ``evalf()`` or ``lambdify`` Returns ------- afunc : sympy.FunctionClass instance function with attached implementation Examples ======== >>> from sympy.abc import x >>> from sympy.utilities.lambdify import lambdify, implemented_function >>> from sympy import Function >>> f = implemented_function('f', lambda x: x+1) >>> lam_f = lambdify(x, f(x)) >>> lam_f(4) 5 """ # Delayed import to avoid circular imports from sympy.core.function import UndefinedFunction # if name, create function to hold implementation _extra_kwargs = {} if isinstance(symfunc, UndefinedFunction): _extra_kwargs = symfunc._extra_kwargs symfunc = symfunc.__name__ if isinstance(symfunc, string_types): # Keyword arguments to UndefinedFunction are added as attributes to # the created class. symfunc = UndefinedFunction(symfunc, _imp_=staticmethod(implementation), **_extra_kwargs) elif not isinstance(symfunc, UndefinedFunction): raise ValueError('symfunc should be either a string or' ' an UndefinedFunction instance.') return symfunc
e45969b507ef1a426f934618eb62a0bbb0dd76cd7506d85d4c8485ba12c58659	from __future__ import print_function, division from sympy.core.compatibility import range """ Algorithms and classes to support enumerative combinatorics. Currently just multiset partitions, but more could be added. Terminology (following Knuth, algorithm 7.1.2.5M TAOCP) multiset aaabbcccc has a partition aaabc \| bccc The submultisets, aaabc and bccc of the partition are called parts, or sometimes vectors. (Knuth notes that multiset partitions can be thought of as partitions of vectors of integers, where the ith element of the vector gives the multiplicity of element i.) The values a, b and c are components of the multiset. These correspond to elements of a set, but in a multiset can be present with a multiplicity greater than 1. The algorithm deserves some explanation. Think of the part aaabc from the multiset above. If we impose an ordering on the components of the multiset, we can represent a part with a vector, in which the value of the first element of the vector corresponds to the multiplicity of the first component in that part. Thus, aaabc can be represented by the vector [3, 1, 1]. We can also define an ordering on parts, based on the lexicographic ordering of the vector (leftmost vector element, i.e., the element with the smallest component number, is the most significant), so that [3, 1, 1] > [3, 1, 0] and [3, 1, 1] > [2, 1, 4]. The ordering on parts can be extended to an ordering on partitions: First, sort the parts in each partition, left-to-right in decreasing order. Then partition A is greater than partition B if A's leftmost/greatest part is greater than B's leftmost part. If the leftmost parts are equal, compare the second parts, and so on. In this ordering, the greatest partition of a given multiset has only one part. The least partition is the one in which the components are spread out, one per part. The enumeration algorithms in this file yield the partitions of the argument multiset in decreasing order. The main data structure is a stack of parts, corresponding to the current partition. An important invariant is that the parts on the stack are themselves in decreasing order. This data structure is decremented to find the next smaller partition. Most often, decrementing the partition will only involve adjustments to the smallest parts at the top of the stack, much as adjacent integers usually differ only in their last few digits. Knuth's algorithm uses two main operations on parts: Decrement - change the part so that it is smaller in the (vector) lexicographic order, but reduced by the smallest amount possible. For example, if the multiset has vector [5, 3, 1], and the bottom/greatest part is [4, 2, 1], this part would decrement to [4, 2, 0], while [4, 0, 0] would decrement to [3, 3, 1]. A singleton part is never decremented -- [1, 0, 0] is not decremented to [0, 3, 1]. Instead, the decrement operator needs to fail for this case. In Knuth's pseudocode, the decrement operator is step m5. Spread unallocated multiplicity - Once a part has been decremented, it cannot be the rightmost part in the partition. There is some multiplicity that has not been allocated, and new parts must be created above it in the stack to use up this multiplicity. To maintain the invariant that the parts on the stack are in decreasing order, these new parts must be less than or equal to the decremented part. For example, if the multiset is [5, 3, 1], and its most significant part has just been decremented to [5, 3, 0], the spread operation will add a new part so that the stack becomes [[5, 3, 0], [0, 0, 1]]. If the most significant part (for the same multiset) has been decremented to [2, 0, 0] the stack becomes [[2, 0, 0], [2, 0, 0], [1, 3, 1]]. In the pseudocode, the spread operation for one part is step m2. The complete spread operation is a loop of steps m2 and m3. In order to facilitate the spread operation, Knuth stores, for each component of each part, not just the multiplicity of that component in the part, but also the total multiplicity available for this component in this part or any lesser part above it on the stack. One added twist is that Knuth does not represent the part vectors as arrays. Instead, he uses a sparse representation, in which a component of a part is represented as a component number (c), plus the multiplicity of the component in that part (v) as well as the total multiplicity available for that component (u). This saves time that would be spent skipping over zeros. """ class PartComponent(object): """Internal class used in support of the multiset partitions enumerators and the associated visitor functions. Represents one component of one part of the current partition. A stack of these, plus an auxiliary frame array, f, represents a partition of the multiset. Knuth's pseudocode makes c, u, and v separate arrays. """ __slots__ = ('c', 'u', 'v') def __init__(self): self.c = 0 # Component number self.u = 0 # The as yet unpartitioned amount in component c # before it is allocated by this triple self.v = 0 # Amount of c component in the current part # (v<=u). An invariant of the representation is # that the next higher triple for this component # (if there is one) will have a value of u-v in # its u attribute. def __repr__(self): "for debug/algorithm animation purposes" return 'c:%d u:%d v:%d' % (self.c, self.u, self.v) def __eq__(self, other): """Define value oriented equality, which is useful for testers""" return (isinstance(other, self.__class__) and self.c == other.c and self.u == other.u and self.v == other.v) def __ne__(self, other): """Defined for consistency with __eq__""" return not self == other # This function tries to be a faithful implementation of algorithm # 7.1.2.5M in Volume 4A, Combinatoral Algorithms, Part 1, of The Art # of Computer Programming, by Donald Knuth. This includes using # (mostly) the same variable names, etc. This makes for rather # low-level Python. # Changes from Knuth's pseudocode include # - use PartComponent struct/object instead of 3 arrays # - make the function a generator # - map (with some difficulty) the GOTOs to Python control structures. # - Knuth uses 1-based numbering for components, this code is 0-based # - renamed variable l to lpart. # - flag variable x takes on values True/False instead of 1/0 # def multiset_partitions_taocp(multiplicities): """Enumerates partitions of a multiset. Parameters ========== multiplicities list of integer multiplicities of the components of the multiset. Yields ====== state Internal data structure which encodes a particular partition. This output is then usually processed by a vistor function which combines the information from this data structure with the components themselves to produce an actual partition. Unless they wish to create their own visitor function, users will have little need to look inside this data structure. But, for reference, it is a 3-element list with components: f is a frame array, which is used to divide pstack into parts. lpart points to the base of the topmost part. pstack is an array of PartComponent objects. The ``state`` output offers a peek into the internal data structures of the enumeration function. The client should treat this as read-only; any modification of the data structure will cause unpredictable (and almost certainly incorrect) results. Also, the components of ``state`` are modified in place at each iteration. Hence, the visitor must be called at each loop iteration. Accumulating the ``state`` instances and processing them later will not work. Examples ======== >>> from sympy.utilities.enumerative import list_visitor >>> from sympy.utilities.enumerative import multiset_partitions_taocp >>> # variables components and multiplicities represent the multiset 'abb' >>> components = 'ab' >>> multiplicities = [1, 2] >>> states = multiset_partitions_taocp(multiplicities) >>> list(list_visitor(state, components) for state in states) [[['a', 'b', 'b']], [['a', 'b'], ['b']], [['a'], ['b', 'b']], [['a'], ['b'], ['b']]] See Also ======== sympy.utilities.iterables.multiset_partitions: Takes a multiset as input and directly yields multiset partitions. It dispatches to a number of functions, including this one, for implementation. Most users will find it more convenient to use than multiset_partitions_taocp. """ # Important variables. # m is the number of components, i.e., number of distinct elements m = len(multiplicities) # n is the cardinality, total number of elements whether or not distinct n = sum(multiplicities) # The main data structure, f segments pstack into parts. See # list_visitor() for example code indicating how this internal # state corresponds to a partition. # Note: allocation of space for stack is conservative. Knuth's # exercise 7.2.1.5.68 gives some indication of how to tighten this # bound, but this is not implemented. pstack = [PartComponent() for i in range(n * m + 1)] f = [0] * (n + 1) # Step M1 in Knuth (Initialize) # Initial state - entire multiset in one part. for j in range(m): ps = pstack[j] ps.c = j ps.u = multiplicities[j] ps.v = multiplicities[j] # Other variables f[0] = 0 a = 0 lpart = 0 f[1] = m b = m # in general, current stack frame is from a to b - 1 while True: while True: # Step M2 (Subtract v from u) j = a k = b x = False while j < b: pstack[k].u = pstack[j].u - pstack[j].v if pstack[k].u == 0: x = True elif not x: pstack[k].c = pstack[j].c pstack[k].v = min(pstack[j].v, pstack[k].u) x = pstack[k].u < pstack[j].v k = k + 1 else: # x is True pstack[k].c = pstack[j].c pstack[k].v = pstack[k].u k = k + 1 j = j + 1 # Note: x is True iff v has changed # Step M3 (Push if nonzero.) if k > b: a = b b = k lpart = lpart + 1 f[lpart + 1] = b # Return to M2 else: break # Continue to M4 # M4 Visit a partition state = [f, lpart, pstack] yield state # M5 (Decrease v) while True: j = b-1 while (pstack[j].v == 0): j = j - 1 if j == a and pstack[j].v == 1: # M6 (Backtrack) if lpart == 0: return lpart = lpart - 1 b = a a = f[lpart] # Return to M5 else: pstack[j].v = pstack[j].v - 1 for k in range(j + 1, b): pstack[k].v = pstack[k].u break # GOTO M2 # --------------- Visitor functions for multiset partitions --------------- # A visitor takes the partition state generated by # multiset_partitions_taocp or other enumerator, and produces useful # output (such as the actual partition). def factoring_visitor(state, primes): """Use with multiset_partitions_taocp to enumerate the ways a number can be expressed as a product of factors. For this usage, the exponents of the prime factors of a number are arguments to the partition enumerator, while the corresponding prime factors are input here. Examples ======== To enumerate the factorings of a number we can think of the elements of the partition as being the prime factors and the multiplicities as being their exponents. >>> from sympy.utilities.enumerative import factoring_visitor >>> from sympy.utilities.enumerative import multiset_partitions_taocp >>> from sympy import factorint >>> primes, multiplicities = zip(factorint(24).items()) >>> primes (2, 3) >>> multiplicities (3, 1) >>> states = multiset_partitions_taocp(multiplicities) >>> list(factoring_visitor(state, primes) for state in states) [[24], [8, 3], [12, 2], [4, 6], [4, 2, 3], [6, 2, 2], [2, 2, 2, 3]] """ f, lpart, pstack = state factoring = [] for i in range(lpart + 1): factor = 1 for ps in pstack[f[i]: f[i + 1]]: if ps.v > 0: factor = primes[ps.c] ** ps.v factoring.append(factor) return factoring def list_visitor(state, components): """Return a list of lists to represent the partition. Examples ======== >>> from sympy.utilities.enumerative import list_visitor >>> from sympy.utilities.enumerative import multiset_partitions_taocp >>> states = multiset_partitions_taocp([1, 2, 1]) >>> s = next(states) >>> list_visitor(s, 'abc') # for multiset 'a b b c' [['a', 'b', 'b', 'c']] >>> s = next(states) >>> list_visitor(s, [1, 2, 3]) # for multiset '1 2 2 3 [[1, 2, 2], [3]] """ f, lpart, pstack = state partition = [] for i in range(lpart+1): part = [] for ps in pstack[f[i]:f[i+1]]: if ps.v > 0: part.extend([components[ps.c]] * ps.v) partition.append(part) return partition class MultisetPartitionTraverser(): """ Has methods to ``enumerate`` and ``count`` the partitions of a multiset. This implements a refactored and extended version of Knuth's algorithm 7.1.2.5M [AOCP]_." The enumeration methods of this class are generators and return data structures which can be interpreted by the same visitor functions used for the output of ``multiset_partitions_taocp``. Examples ======== >>> from sympy.utilities.enumerative import MultisetPartitionTraverser >>> m = MultisetPartitionTraverser() >>> m.count_partitions([4,4,4,2]) 127750 >>> m.count_partitions([3,3,3]) 686 See Also ======== multiset_partitions_taocp sympy.utilities.iterables.multiset_partititions References ========== .. [AOCP] Algorithm 7.1.2.5M in Volume 4A, Combinatoral Algorithms, Part 1, of The Art of Computer Programming, by Donald Knuth. .. [Factorisatio] On a Problem of Oppenheim concerning "Factorisatio Numerorum" E. R. Canfield, Paul Erdos, Carl Pomerance, JOURNAL OF NUMBER THEORY, Vol. 17, No. 1. August 1983. See section 7 for a description of an algorithm similar to Knuth's. .. [Yorgey] Generating Multiset Partitions, Brent Yorgey, The Monad.Reader, Issue 8, September 2007. """ def __init__(self): self.debug = False # TRACING variables. These are useful for gathering # statistics on the algorithm itself, but have no particular # benefit to a user of the code. self.k1 = 0 self.k2 = 0 self.p1 = 0 def db_trace(self, msg): """Useful for usderstanding/debugging the algorithms. Not generally activated in end-user code.""" if self.debug: letters = 'abcdefghijklmnopqrstuvwxyz' state = [self.f, self.lpart, self.pstack] print("DBG:", msg, ["".join(part) for part in list_visitor(state, letters)], animation_visitor(state)) # # Helper methods for enumeration # def _initialize_enumeration(self, multiplicities): """Allocates and initializes the partition stack. This is called from the enumeration/counting routines, so there is no need to call it separately.""" num_components = len(multiplicities) # cardinality is the total number of elements, whether or not distinct cardinality = sum(multiplicities) # pstack is the partition stack, which is segmented by # f into parts. self.pstack = [PartComponent() for i in range(num_components * cardinality + 1)] self.f = [0] * (cardinality + 1) # Initial state - entire multiset in one part. for j in range(num_components): ps = self.pstack[j] ps.c = j ps.u = multiplicities[j] ps.v = multiplicities[j] self.f[0] = 0 self.f[1] = num_components self.lpart = 0 # The decrement_part() method corresponds to step M5 in Knuth's # algorithm. This is the base version for enum_all(). Modified # versions of this method are needed if we want to restrict # sizes of the partitions produced. def decrement_part(self, part): """Decrements part (a subrange of pstack), if possible, returning True iff the part was successfully decremented. If you think of the v values in the part as a multi-digit integer (least significant digit on the right) this is basically decrementing that integer, but with the extra constraint that the leftmost digit cannot be decremented to 0. Parameters ========== part The part, represented as a list of PartComponent objects, which is to be decremented. """ plen = len(part) for j in range(plen - 1, -1, -1): if (j == 0 and part[j].v > 1) or (j > 0 and part[j].v > 0): # found val to decrement part[j].v -= 1 # Reset trailing parts back to maximum for k in range(j + 1, plen): part[k].v = part[k].u return True return False # Version to allow number of parts to be bounded from above. # Corresponds to (a modified) step M5. def decrement_part_small(self, part, ub): """Decrements part (a subrange of pstack), if possible, returning True iff the part was successfully decremented. Parameters ========== part part to be decremented (topmost part on the stack) ub the maximum number of parts allowed in a partition returned by the calling traversal. Notes ===== The goal of this modification of the ordinary decrement method is to fail (meaning that the subtree rooted at this part is to be skipped) when it can be proved that this part can only have child partitions which are larger than allowed by ``ub``. If a decision is made to fail, it must be accurate, otherwise the enumeration will miss some partitions. But, it is OK not to capture all the possible failures -- if a part is passed that shouldn't be, the resulting too-large partitions are filtered by the enumeration one level up. However, as is usual in constrained enumerations, failing early is advantageous. The tests used by this method catch the most common cases, although this implementation is by no means the last word on this problem. The tests include: 1) ``lpart`` must be less than ``ub`` by at least 2. This is because once a part has been decremented, the partition will gain at least one child in the spread step. 2) If the leading component of the part is about to be decremented, check for how many parts will be added in order to use up the unallocated multiplicity in that leading component, and fail if this number is greater than allowed by ``ub``. (See code for the exact expression.) This test is given in the answer to Knuth's problem 7.2.1.5.69. 3) If there is exactly enough room to expand the leading component by the above test, check the next component (if it exists) once decrementing has finished. If this has ``v == 0``, this next component will push the expansion over the limit by 1, so fail. """ if self.lpart >= ub - 1: self.p1 += 1 # increment to keep track of usefulness of tests return False plen = len(part) for j in range(plen - 1, -1, -1): # Knuth's mod, (answer to problem 7.2.1.5.69) if (j == 0) and (part[0].v - 1)(ub - self.lpart) < part[0].u: self.k1 += 1 return False if (j == 0 and part[j].v > 1) or (j > 0 and part[j].v > 0): # found val to decrement part[j].v -= 1 # Reset trailing parts back to maximum for k in range(j + 1, plen): part[k].v = part[k].u # Have now decremented part, but are we doomed to # failure when it is expanded? Check one oddball case # that turns out to be surprisingly common - exactly # enough room to expand the leading component, but no # room for the second component, which has v=0. if (plen > 1 and (part[1].v == 0) and (part[0].u - part[0].v) == ((ub - self.lpart - 1) part[0].v)): self.k2 += 1 self.db_trace("Decrement fails test 3") return False return True return False def decrement_part_large(self, part, amt, lb): """Decrements part, while respecting size constraint. A part can have no children which are of sufficient size (as indicated by ``lb``) unless that part has sufficient unallocated multiplicity. When enforcing the size constraint, this method will decrement the part (if necessary) by an amount needed to ensure sufficient unallocated multiplicity. Returns True iff the part was successfully decremented. Parameters ========== part part to be decremented (topmost part on the stack) amt Can only take values 0 or 1. A value of 1 means that the part must be decremented, and then the size constraint is enforced. A value of 0 means just to enforce the ``lb`` size constraint. lb The partitions produced by the calling enumeration must have more parts than this value. """ if amt == 1: # In this case we always need to increment, before # enforcing the "sufficient unallocated multiplicity" # constraint. Easiest for this is just to call the # regular decrement method. if not self.decrement_part(part): return False # Next, perform any needed additional decrementing to respect # "sufficient unallocated multiplicity" (or fail if this is # not possible). min_unalloc = lb - self.lpart if min_unalloc <= 0: return True total_mult = sum(pc.u for pc in part) total_alloc = sum(pc.v for pc in part) if total_mult <= min_unalloc: return False deficit = min_unalloc - (total_mult - total_alloc) if deficit <= 0: return True for i in range(len(part) - 1, -1, -1): if i == 0: if part[0].v > deficit: part[0].v -= deficit return True else: return False # This shouldn't happen, due to above check else: if part[i].v >= deficit: part[i].v -= deficit return True else: deficit -= part[i].v part[i].v = 0 def decrement_part_range(self, part, lb, ub): """Decrements part (a subrange of pstack), if possible, returning True iff the part was successfully decremented. Parameters ========== part part to be decremented (topmost part on the stack) ub the maximum number of parts allowed in a partition returned by the calling traversal. lb The partitions produced by the calling enumeration must have more parts than this value. Notes ===== Combines the constraints of _small and _large decrement methods. If returns success, part has been decremented at least once, but perhaps by quite a bit more if needed to meet the lb constraint. """ # Constraint in the range case is just enforcing both the # constraints from _small and _large cases. Note the 0 as the # second argument to the _large call -- this is the signal to # decrement only as needed to for constraint enforcement. The # short circuiting and left-to-right order of the 'and' # operator is important for this to work correctly. return self.decrement_part_small(part, ub) and \ self.decrement_part_large(part, 0, lb) def spread_part_multiplicity(self): """Returns True if a new part has been created, and adjusts pstack, f and lpart as needed. Notes ===== Spreads unallocated multiplicity from the current top part into a new part created above the current on the stack. This new part is constrained to be less than or equal to the old in terms of the part ordering. This call does nothing (and returns False) if the current top part has no unallocated multiplicity. """ j = self.f[self.lpart] # base of current top part k = self.f[self.lpart + 1] # ub of current; potential base of next base = k # save for later comparison changed = False # Set to true when the new part (so far) is # strictly less than (as opposed to less than # or equal) to the old. for j in range(self.f[self.lpart], self.f[self.lpart + 1]): self.pstack[k].u = self.pstack[j].u - self.pstack[j].v if self.pstack[k].u == 0: changed = True else: self.pstack[k].c = self.pstack[j].c if changed: # Put all available multiplicity in this part self.pstack[k].v = self.pstack[k].u else: # Still maintaining ordering constraint if self.pstack[k].u < self.pstack[j].v: self.pstack[k].v = self.pstack[k].u changed = True else: self.pstack[k].v = self.pstack[j].v k = k + 1 if k > base: # Adjust for the new part on stack self.lpart = self.lpart + 1 self.f[self.lpart + 1] = k return True return False def top_part(self): """Return current top part on the stack, as a slice of pstack. """ return self.pstack[self.f[self.lpart]:self.f[self.lpart + 1]] # Same interface and functionality as multiset_partitions_taocp(), # but some might find this refactored version easier to follow. def enum_all(self, multiplicities): """Enumerate the partitions of a multiset. Examples ======== >>> from sympy.utilities.enumerative import list_visitor >>> from sympy.utilities.enumerative import MultisetPartitionTraverser >>> m = MultisetPartitionTraverser() >>> states = m.enum_all([2,2]) >>> list(list_visitor(state, 'ab') for state in states) [[['a', 'a', 'b', 'b']], [['a', 'a', 'b'], ['b']], [['a', 'a'], ['b', 'b']], [['a', 'a'], ['b'], ['b']], [['a', 'b', 'b'], ['a']], [['a', 'b'], ['a', 'b']], [['a', 'b'], ['a'], ['b']], [['a'], ['a'], ['b', 'b']], [['a'], ['a'], ['b'], ['b']]] See Also ======== multiset_partitions_taocp(): which provides the same result as this method, but is about twice as fast. Hence, enum_all is primarily useful for testing. Also see the function for a discussion of states and visitors. """ self._initialize_enumeration(multiplicities) while True: while self.spread_part_multiplicity(): pass # M4 Visit a partition state = [self.f, self.lpart, self.pstack] yield state # M5 (Decrease v) while not self.decrement_part(self.top_part()): # M6 (Backtrack) if self.lpart == 0: return self.lpart -= 1 def enum_small(self, multiplicities, ub): """Enumerate multiset partitions with no more than ``ub`` parts. Equivalent to enum_range(multiplicities, 0, ub) Parameters ========== multiplicities list of multiplicities of the components of the multiset. ub Maximum number of parts Examples ======== >>> from sympy.utilities.enumerative import list_visitor >>> from sympy.utilities.enumerative import MultisetPartitionTraverser >>> m = MultisetPartitionTraverser() >>> states = m.enum_small([2,2], 2) >>> list(list_visitor(state, 'ab') for state in states) [[['a', 'a', 'b', 'b']], [['a', 'a', 'b'], ['b']], [['a', 'a'], ['b', 'b']], [['a', 'b', 'b'], ['a']], [['a', 'b'], ['a', 'b']]] The implementation is based, in part, on the answer given to exercise 69, in Knuth [AOCP]_. See Also ======== enum_all, enum_large, enum_range """ # Keep track of iterations which do not yield a partition. # Clearly, we would like to keep this number small. self.discarded = 0 if ub <= 0: return self._initialize_enumeration(multiplicities) while True: good_partition = True while self.spread_part_multiplicity(): self.db_trace("spread 1") if self.lpart >= ub: self.discarded += 1 good_partition = False self.db_trace(" Discarding") self.lpart = ub - 2 break # M4 Visit a partition if good_partition: state = [self.f, self.lpart, self.pstack] yield state # M5 (Decrease v) while not self.decrement_part_small(self.top_part(), ub): self.db_trace("Failed decrement, going to backtrack") # M6 (Backtrack) if self.lpart == 0: return self.lpart -= 1 self.db_trace("Backtracked to") self.db_trace("decrement ok, about to expand") def enum_large(self, multiplicities, lb): """Enumerate the partitions of a multiset with lb < num(parts) Equivalent to enum_range(multiplicities, lb, sum(multiplicities)) Parameters ========== multiplicities list of multiplicities of the components of the multiset. lb Number of parts in the partition must be greater than this lower bound. Examples ======== >>> from sympy.utilities.enumerative import list_visitor >>> from sympy.utilities.enumerative import MultisetPartitionTraverser >>> m = MultisetPartitionTraverser() >>> states = m.enum_large([2,2], 2) >>> list(list_visitor(state, 'ab') for state in states) [[['a', 'a'], ['b'], ['b']], [['a', 'b'], ['a'], ['b']], [['a'], ['a'], ['b', 'b']], [['a'], ['a'], ['b'], ['b']]] See Also ======== enum_all, enum_small, enum_range """ self.discarded = 0 if lb >= sum(multiplicities): return self._initialize_enumeration(multiplicities) self.decrement_part_large(self.top_part(), 0, lb) while True: good_partition = True while self.spread_part_multiplicity(): if not self.decrement_part_large(self.top_part(), 0, lb): # Failure here should be rare/impossible self.discarded += 1 good_partition = False break # M4 Visit a partition if good_partition: state = [self.f, self.lpart, self.pstack] yield state # M5 (Decrease v) while not self.decrement_part_large(self.top_part(), 1, lb): # M6 (Backtrack) if self.lpart == 0: return self.lpart -= 1 def enum_range(self, multiplicities, lb, ub): """Enumerate the partitions of a multiset with ``lb < num(parts) <= ub``. In particular, if partitions with exactly ``k`` parts are desired, call with ``(multiplicities, k - 1, k)``. This method generalizes enum_all, enum_small, and enum_large. Examples ======== >>> from sympy.utilities.enumerative import list_visitor >>> from sympy.utilities.enumerative import MultisetPartitionTraverser >>> m = MultisetPartitionTraverser() >>> states = m.enum_range([2,2], 1, 2) >>> list(list_visitor(state, 'ab') for state in states) [[['a', 'a', 'b'], ['b']], [['a', 'a'], ['b', 'b']], [['a', 'b', 'b'], ['a']], [['a', 'b'], ['a', 'b']]] """ # combine the constraints of the _large and _small # enumerations. self.discarded = 0 if ub <= 0 or lb >= sum(multiplicities): return self._initialize_enumeration(multiplicities) self.decrement_part_large(self.top_part(), 0, lb) while True: good_partition = True while self.spread_part_multiplicity(): self.db_trace("spread 1") if not self.decrement_part_large(self.top_part(), 0, lb): # Failure here - possible in range case? self.db_trace(" Discarding (large cons)") self.discarded += 1 good_partition = False break elif self.lpart >= ub: self.discarded += 1 good_partition = False self.db_trace(" Discarding small cons") self.lpart = ub - 2 break # M4 Visit a partition if good_partition: state = [self.f, self.lpart, self.pstack] yield state # M5 (Decrease v) while not self.decrement_part_range(self.top_part(), lb, ub): self.db_trace("Failed decrement, going to backtrack") # M6 (Backtrack) if self.lpart == 0: return self.lpart -= 1 self.db_trace("Backtracked to") self.db_trace("decrement ok, about to expand") def count_partitions_slow(self, multiplicities): """Returns the number of partitions of a multiset whose elements have the multiplicities given in ``multiplicities``. Primarily for comparison purposes. It follows the same path as enumerate, and counts, rather than generates, the partitions. See Also ======== count_partitions Has the same calling interface, but is much faster. """ # number of partitions so far in the enumeration self.pcount = 0 self._initialize_enumeration(multiplicities) while True: while self.spread_part_multiplicity(): pass # M4 Visit (count) a partition self.pcount += 1 # M5 (Decrease v) while not self.decrement_part(self.top_part()): # M6 (Backtrack) if self.lpart == 0: return self.pcount self.lpart -= 1 def count_partitions(self, multiplicities): """Returns the number of partitions of a multiset whose components have the multiplicities given in ``multiplicities``. For larger counts, this method is much faster than calling one of the enumerators and counting the result. Uses dynamic programming to cut down on the number of nodes actually explored. The dictionary used in order to accelerate the counting process is stored in the ``MultisetPartitionTraverser`` object and persists across calls. If the user does not expect to call ``count_partitions`` for any additional multisets, the object should be cleared to save memory. On the other hand, the cache built up from one count run can significantly speed up subsequent calls to ``count_partitions``, so it may be advantageous not to clear the object. Examples ======== >>> from sympy.utilities.enumerative import MultisetPartitionTraverser >>> m = MultisetPartitionTraverser() >>> m.count_partitions([9,8,2]) 288716 >>> m.count_partitions([2,2]) 9 >>> del m Notes ===== If one looks at the workings of Knuth's algorithm M [AOCP]_, it can be viewed as a traversal of a binary tree of parts. A part has (up to) two children, the left child resulting from the spread operation, and the right child from the decrement operation. The ordinary enumeration of multiset partitions is an in-order traversal of this tree, and with the partitions corresponding to paths from the root to the leaves. The mapping from paths to partitions is a little complicated, since the partition would contain only those parts which are leaves or the parents of a spread link, not those which are parents of a decrement link. For counting purposes, it is sufficient to count leaves, and this can be done with a recursive in-order traversal. The number of leaves of a subtree rooted at a particular part is a function only of that part itself, so memoizing has the potential to speed up the counting dramatically. This method follows a computational approach which is similar to the hypothetical memoized recursive function, but with two differences: 1) This method is iterative, borrowing its structure from the other enumerations and maintaining an explicit stack of parts which are in the process of being counted. (There may be multisets which can be counted reasonably quickly by this implementation, but which would overflow the default Python recursion limit with a recursive implementation.) 2) Instead of using the part data structure directly, a more compact key is constructed. This saves space, but more importantly coalesces some parts which would remain separate with physical keys. Unlike the enumeration functions, there is currently no _range version of count_partitions. If someone wants to stretch their brain, it should be possible to construct one by memoizing with a histogram of counts rather than a single count, and combining the histograms. """ # number of partitions so far in the enumeration self.pcount = 0 # dp_stack is list of lists of (part_key, start_count) pairs self.dp_stack = [] # dp_map is map part_key-> count, where count represents the # number of multiset which are descendants of a part with this # key, or any of its decrements # Thus, when we find a part in the map, we add its count # value to the running total, cut off the enumeration, and # backtrack if not hasattr(self, 'dp_map'): self.dp_map = {} self._initialize_enumeration(multiplicities) pkey = part_key(self.top_part()) self.dp_stack.append([(pkey, 0), ]) while True: while self.spread_part_multiplicity(): pkey = part_key(self.top_part()) if pkey in self.dp_map: # Already have a cached value for the count of the # subtree rooted at this part. Add it to the # running counter, and break out of the spread # loop. The -1 below is to compensate for the # leaf that this code path would otherwise find, # and which gets incremented for below. self.pcount += (self.dp_map[pkey] - 1) self.lpart -= 1 break else: self.dp_stack.append([(pkey, self.pcount), ]) # M4 count a leaf partition self.pcount += 1 # M5 (Decrease v) while not self.decrement_part(self.top_part()): # M6 (Backtrack) for key, oldcount in self.dp_stack.pop(): self.dp_map[key] = self.pcount - oldcount if self.lpart == 0: return self.pcount self.lpart -= 1 # At this point have successfully decremented the part on # the stack and it does not appear in the cache. It needs # to be added to the list at the top of dp_stack pkey = part_key(self.top_part()) self.dp_stack[-1].append((pkey, self.pcount),) def part_key(part): """Helper for MultisetPartitionTraverser.count_partitions that creates a key for ``part``, that only includes information which can affect the count for that part. (Any irrelevant information just reduces the effectiveness of dynamic programming.) Notes ===== This member function is a candidate for future exploration. There are likely symmetries that can be exploited to coalesce some ``part_key`` values, and thereby save space and improve performance. """ # The component number is irrelevant for counting partitions, so # leave it out of the memo key. rval = [] for ps in part: rval.append(ps.u) rval.append(ps.v) return tuple(rval)
d6256df7c8c3561d33e0f9b704ff0de425e94cb819cbc89f2e62b2449d731268	from __future__ import print_function, division from sympy.core.compatibility import range from sympy.core.decorators import wraps def recurrence_memo(initial): """ Memo decorator for sequences defined by recurrence See usage examples e.g. in the specfun/combinatorial module """ cache = initial def decorator(f): @wraps(f) def g(n): L = len(cache) if n <= L - 1: return cache[n] for i in range(L, n + 1): cache.append(f(i, cache)) return cache[-1] return g return decorator def assoc_recurrence_memo(base_seq): """ Memo decorator for associated sequences defined by recurrence starting from base base_seq(n) -- callable to get base sequence elements XXX works only for Pn0 = base_seq(0) cases XXX works only for m <= n cases """ cache = [] def decorator(f): @wraps(f) def g(n, m): L = len(cache) if n < L: return cache[n][m] for i in range(L, n + 1): # get base sequence F_i0 = base_seq(i) F_i_cache = [F_i0] cache.append(F_i_cache) # XXX only works for m <= n cases # generate assoc sequence for j in range(1, i + 1): F_ij = f(i, j, cache) F_i_cache.append(F_ij) return cache[n][m] return g return decorator
4d2c8ef4eeffe8ba73f02cf187894d38b0ed513d855efd4e05e6b00e40f583b7	""" Helpers for randomized testing """ from __future__ import print_function, division from random import uniform, Random, randrange, randint from sympy.core.compatibility import is_sequence, as_int from sympy.core.containers import Tuple from sympy.core.numbers import comp, I from sympy.core.symbol import Symbol from sympy.simplify.simplify import nsimplify def random_complex_number(a=2, b=-1, c=3, d=1, rational=False, tolerance=None): """ Return a random complex number. To reduce chance of hitting branch cuts or anything, we guarantee b <= Im z <= d, a <= Re z <= c When rational is True, a rational approximation to a random number is obtained within specified tolerance, if any. """ A, B = uniform(a, c), uniform(b, d) if not rational: return A + IB return (nsimplify(A, rational=True, tolerance=tolerance) + Insimplify(B, rational=True, tolerance=tolerance)) def verify_numerically(f, g, z=None, tol=1.0e-6, a=2, b=-1, c=3, d=1): """ Test numerically that f and g agree when evaluated in the argument z. If z is None, all symbols will be tested. This routine does not test whether there are Floats present with precision higher than 15 digits so if there are, your results may not be what you expect due to round- off errors. Examples ======== >>> from sympy import sin, cos >>> from sympy.abc import x >>> from sympy.utilities.randtest import verify_numerically as tn >>> tn(sin(x)2 + cos(x)2, 1, x) True """ f, g, z = Tuple(f, g, z) z = [z] if isinstance(z, Symbol) else (f.free_symbols \| g.free_symbols) reps = list(zip(z, [random_complex_number(a, b, c, d) for zi in z])) z1 = f.subs(reps).n() z2 = g.subs(reps).n() return comp(z1, z2, tol) def test_derivative_numerically(f, z, tol=1.0e-6, a=2, b=-1, c=3, d=1): """ Test numerically that the symbolically computed derivative of f with respect to z is correct. This routine does not test whether there are Floats present with precision higher than 15 digits so if there are, your results may not be what you expect due to round-off errors. Examples ======== >>> from sympy import sin >>> from sympy.abc import x >>> from sympy.utilities.randtest import test_derivative_numerically as td >>> td(sin(x), x) True """ from sympy.core.function import Derivative z0 = random_complex_number(a, b, c, d) f1 = f.diff(z).subs(z, z0) f2 = Derivative(f, z).doit_numerically(z0) return comp(f1.n(), f2.n(), tol) def _randrange(seed=None): """Return a randrange generator. ``seed`` can be o None - return randomly seeded generator o int - return a generator seeded with the int o list - the values to be returned will be taken from the list in the order given; the provided list is not modified. Examples ======== >>> from sympy.utilities.randtest import _randrange >>> rr = _randrange() >>> rr(1000) # doctest: +SKIP 999 >>> rr = _randrange(3) >>> rr(1000) # doctest: +SKIP 238 >>> rr = _randrange([0, 5, 1, 3, 4]) >>> rr(3), rr(3) (0, 1) """ if seed is None: return randrange elif isinstance(seed, int): return Random(seed).randrange elif is_sequence(seed): seed = list(seed) # make a copy seed.reverse() def give(a, b=None, seq=seed): if b is None: a, b = 0, a a, b = as_int(a), as_int(b) w = b - a if w < 1: raise ValueError('_randrange got empty range') try: x = seq.pop() except AttributeError: raise ValueError('_randrange expects a list-like sequence') except IndexError: raise ValueError('_randrange sequence was too short') if a <= x < b: return x else: return give(a, b, seq) return give else: raise ValueError('_randrange got an unexpected seed') def _randint(seed=None): """Return a randint generator. ``seed`` can be o None - return randomly seeded generator o int - return a generator seeded with the int o list - the values to be returned will be taken from the list in the order given; the provided list is not modified. Examples ======== >>> from sympy.utilities.randtest import _randint >>> ri = _randint() >>> ri(1, 1000) # doctest: +SKIP 999 >>> ri = _randint(3) >>> ri(1, 1000) # doctest: +SKIP 238 >>> ri = _randint([0, 5, 1, 2, 4]) >>> ri(1, 3), ri(1, 3) (1, 2) """ if seed is None: return randint elif isinstance(seed, int): return Random(seed).randint elif is_sequence(seed): seed = list(seed) # make a copy seed.reverse() def give(a, b, seq=seed): a, b = as_int(a), as_int(b) w = b - a if w < 0: raise ValueError('_randint got empty range') try: x = seq.pop() except AttributeError: raise ValueError('_randint expects a list-like sequence') except IndexError: raise ValueError('_randint sequence was too short') if a <= x <= b: return x else: return give(a, b, seq) return give else: raise ValueError('_randint got an unexpected seed')
50513085c4f7c3bf054a8a1d19a7bbf7e7241c230c1ca22a498612f6e85ab723	""" A Printer which converts an expression into its LaTeX equivalent. """ from __future__ import print_function, division import itertools from sympy.core import S, Add, Symbol, Mod from sympy.core.sympify import SympifyError from sympy.core.alphabets import greeks from sympy.core.operations import AssocOp from sympy.core.containers import Tuple from sympy.logic.boolalg import true from sympy.core.function import (_coeff_isneg, UndefinedFunction, AppliedUndef, Derivative) ## sympy.printing imports from sympy.printing.precedence import precedence_traditional from .printer import Printer from .conventions import split_super_sub, requires_partial from .precedence import precedence, PRECEDENCE import mpmath.libmp as mlib from mpmath.libmp import prec_to_dps from sympy.core.compatibility import default_sort_key, range from sympy.utilities.iterables import has_variety import re # Hand-picked functions which can be used directly in both LaTeX and MathJax # Complete list at https://docs.mathjax.org/en/latest/tex.html#supported-latex-commands # This variable only contains those functions which sympy uses. accepted_latex_functions = ['arcsin', 'arccos', 'arctan', 'sin', 'cos', 'tan', 'sinh', 'cosh', 'tanh', 'sqrt', 'ln', 'log', 'sec', 'csc', 'cot', 'coth', 're', 'im', 'frac', 'root', 'arg', ] tex_greek_dictionary = { 'Alpha': 'A', 'Beta': 'B', 'Gamma': r'\Gamma', 'Delta': r'\Delta', 'Epsilon': 'E', 'Zeta': 'Z', 'Eta': 'H', 'Theta': r'\Theta', 'Iota': 'I', 'Kappa': 'K', 'Lambda': r'\Lambda', 'Mu': 'M', 'Nu': 'N', 'Xi': r'\Xi', 'omicron': 'o', 'Omicron': 'O', 'Pi': r'\Pi', 'Rho': 'P', 'Sigma': r'\Sigma', 'Tau': 'T', 'Upsilon': r'\Upsilon', 'Phi': r'\Phi', 'Chi': 'X', 'Psi': r'\Psi', 'Omega': r'\Omega', 'lamda': r'\lambda', 'Lamda': r'\Lambda', 'khi': r'\chi', 'Khi': r'X', 'varepsilon': r'\varepsilon', 'varkappa': r'\varkappa', 'varphi': r'\varphi', 'varpi': r'\varpi', 'varrho': r'\varrho', 'varsigma': r'\varsigma', 'vartheta': r'\vartheta', } other_symbols = set(['aleph', 'beth', 'daleth', 'gimel', 'ell', 'eth', 'hbar', 'hslash', 'mho', 'wp', ]) # Variable name modifiers modifier_dict = { # Accents 'mathring': lambda s: r'\mathring{'+s+r'}', 'ddddot': lambda s: r'\ddddot{'+s+r'}', 'dddot': lambda s: r'\dddot{'+s+r'}', 'ddot': lambda s: r'\ddot{'+s+r'}', 'dot': lambda s: r'\dot{'+s+r'}', 'check': lambda s: r'\check{'+s+r'}', 'breve': lambda s: r'\breve{'+s+r'}', 'acute': lambda s: r'\acute{'+s+r'}', 'grave': lambda s: r'\grave{'+s+r'}', 'tilde': lambda s: r'\tilde{'+s+r'}', 'hat': lambda s: r'\hat{'+s+r'}', 'bar': lambda s: r'\bar{'+s+r'}', 'vec': lambda s: r'\vec{'+s+r'}', 'prime': lambda s: "{"+s+"}'", 'prm': lambda s: "{"+s+"}'", # Faces 'bold': lambda s: r'\boldsymbol{'+s+r'}', 'bm': lambda s: r'\boldsymbol{'+s+r'}', 'cal': lambda s: r'\mathcal{'+s+r'}', 'scr': lambda s: r'\mathscr{'+s+r'}', 'frak': lambda s: r'\mathfrak{'+s+r'}', # Brackets 'norm': lambda s: r'\left\\|{'+s+r'}\right\\|', 'avg': lambda s: r'\left\langle{'+s+r'}\right\rangle', 'abs': lambda s: r'\left\|{'+s+r'}\right\|', 'mag': lambda s: r'\left\|{'+s+r'}\right\|', } greek_letters_set = frozenset(greeks) _between_two_numbers_p = ( re.compile(r'[0-9][} ]$'), # search re.compile(r'[{ ][-+0-9]'), # match ) class LatexPrinter(Printer): printmethod = "_latex" _default_settings = { "order": None, "mode": "plain", "itex": False, "fold_frac_powers": False, "fold_func_brackets": False, "fold_short_frac": None, "long_frac_ratio": None, "mul_symbol": None, "inv_trig_style": "abbreviated", "mat_str": None, "mat_delim": "[", "symbol_names": {}, "ln_notation": False, } def __init__(self, settings=None): Printer.__init__(self, settings) if 'mode' in self._settings: valid_modes = ['inline', 'plain', 'equation', 'equation'] if self._settings['mode'] not in valid_modes: raise ValueError("'mode' must be one of 'inline', 'plain', " "'equation' or 'equation'") if self._settings['fold_short_frac'] is None and \ self._settings['mode'] == 'inline': self._settings['fold_short_frac'] = True mul_symbol_table = { None: r" ", "ldot": r" \,.\, ", "dot": r" \cdot ", "times": r" \times " } try: self._settings['mul_symbol_latex'] = \ mul_symbol_table[self._settings['mul_symbol']] except KeyError: self._settings['mul_symbol_latex'] = \ self._settings['mul_symbol'] try: self._settings['mul_symbol_latex_numbers'] = \ mul_symbol_table[self._settings['mul_symbol'] or 'dot'] except KeyError: if (self._settings['mul_symbol'].strip() in ['', ' ', '\\', '\\,', '\\:', '\\;', '\\quad']): self._settings['mul_symbol_latex_numbers'] = \ mul_symbol_table['dot'] else: self._settings['mul_symbol_latex_numbers'] = \ self._settings['mul_symbol'] self._delim_dict = {'(': ')', '[': ']'} def parenthesize(self, item, level, strict=False): prec_val = precedence_traditional(item) if (prec_val < level) or ((not strict) and prec_val <= level): return r"\left(%s\right)" % self._print(item) else: return self._print(item) def doprint(self, expr): tex = Printer.doprint(self, expr) if self._settings['mode'] == 'plain': return tex elif self._settings['mode'] == 'inline': return r"$%s$" % tex elif self._settings['itex']: return r"$$%s$$" % tex else: env_str = self._settings['mode'] return r"\begin{%s}%s\end{%s}" % (env_str, tex, env_str) def _needs_brackets(self, expr): """ Returns True if the expression needs to be wrapped in brackets when printed, False otherwise. For example: a + b => True; a => False; 10 => False; -10 => True. """ return not ((expr.is_Integer and expr.is_nonnegative) or (expr.is_Atom and (expr is not S.NegativeOne and expr.is_Rational is False))) def _needs_function_brackets(self, expr): """ Returns True if the expression needs to be wrapped in brackets when passed as an argument to a function, False otherwise. This is a more liberal version of _needs_brackets, in that many expressions which need to be wrapped in brackets when added/subtracted/raised to a power do not need them when passed to a function. Such an example is ab. """ if not self._needs_brackets(expr): return False else: # Muls of the form abc... can be folded if expr.is_Mul and not self._mul_is_clean(expr): return True # Pows which don't need brackets can be folded elif expr.is_Pow and not self._pow_is_clean(expr): return True # Add and Function always need brackets elif expr.is_Add or expr.is_Function: return True else: return False def _needs_mul_brackets(self, expr, first=False, last=False): """ Returns True if the expression needs to be wrapped in brackets when printed as part of a Mul, False otherwise. This is True for Add, but also for some container objects that would not need brackets when appearing last in a Mul, e.g. an Integral. ``last=True`` specifies that this expr is the last to appear in a Mul. ``first=True`` specifies that this expr is the first to appear in a Mul. """ from sympy import Integral, Piecewise, Product, Sum if expr.is_Mul: if not first and _coeff_isneg(expr): return True elif precedence_traditional(expr) < PRECEDENCE["Mul"]: return True elif expr.is_Relational: return True if expr.is_Piecewise: return True if any([expr.has(x) for x in (Mod,)]): return True if (not last and any([expr.has(x) for x in (Integral, Product, Sum)])): return True return False def _needs_add_brackets(self, expr): """ Returns True if the expression needs to be wrapped in brackets when printed as part of an Add, False otherwise. This is False for most things. """ if expr.is_Relational: return True if any([expr.has(x) for x in (Mod,)]): return True if expr.is_Add: return True return False def _mul_is_clean(self, expr): for arg in expr.args: if arg.is_Function: return False return True def _pow_is_clean(self, expr): return not self._needs_brackets(expr.base) def _do_exponent(self, expr, exp): if exp is not None: return r"\left(%s\right)^{%s}" % (expr, exp) else: return expr def _print_Basic(self, expr): l = [self._print(o) for o in expr.args] return self._deal_with_super_sub(expr.__class__.__name__) + r"\left(%s\right)" % ", ".join(l) def _print_bool(self, e): return r"\mathrm{%s}" % e _print_BooleanTrue = _print_bool _print_BooleanFalse = _print_bool def _print_NoneType(self, e): return r"\mathrm{%s}" % e def _print_Add(self, expr, order=None): if self.order == 'none': terms = list(expr.args) else: terms = self._as_ordered_terms(expr, order=order) tex = "" for i, term in enumerate(terms): if i == 0: pass elif _coeff_isneg(term): tex += " - " term = -term else: tex += " + " term_tex = self._print(term) if self._needs_add_brackets(term): term_tex = r"\left(%s\right)" % term_tex tex += term_tex return tex def _print_Cycle(self, expr): from sympy.combinatorics.permutations import Permutation if expr.size == 0: return r"\left( \right)" expr = Permutation(expr) expr_perm = expr.cyclic_form siz = expr.size if expr.array_form[-1] == siz - 1: expr_perm = expr_perm + [[siz - 1]] term_tex = '' for i in expr_perm: term_tex += str(i).replace(',', r"\;") term_tex = term_tex.replace('[', r"\left( ") term_tex = term_tex.replace(']', r"\right)") return term_tex _print_Permutation = _print_Cycle def _print_Float(self, expr): # Based off of that in StrPrinter dps = prec_to_dps(expr._prec) str_real = mlib.to_str(expr._mpf_, dps, strip_zeros=True) # Must always have a mul symbol (as 2.5 10^{20} just looks odd) # thus we use the number separator separator = self._settings['mul_symbol_latex_numbers'] if 'e' in str_real: (mant, exp) = str_real.split('e') if exp[0] == '+': exp = exp[1:] return r"%s%s10^{%s}" % (mant, separator, exp) elif str_real == "+inf": return r"\infty" elif str_real == "-inf": return r"- \infty" else: return str_real def _print_Cross(self, expr): vec1 = expr._expr1 vec2 = expr._expr2 return r"%s \times %s" % (self.parenthesize(vec1, PRECEDENCE['Mul']), self.parenthesize(vec2, PRECEDENCE['Mul'])) def _print_Curl(self, expr): vec = expr._expr return r"\nabla\times %s" % self.parenthesize(vec, PRECEDENCE['Mul']) def _print_Divergence(self, expr): vec = expr._expr return r"\nabla\cdot %s" % self.parenthesize(vec, PRECEDENCE['Mul']) def _print_Dot(self, expr): vec1 = expr._expr1 vec2 = expr._expr2 return r"%s \cdot %s" % (self.parenthesize(vec1, PRECEDENCE['Mul']), self.parenthesize(vec2, PRECEDENCE['Mul'])) def _print_Gradient(self, expr): func = expr._expr return r"\nabla\cdot %s" % self.parenthesize(func, PRECEDENCE['Mul']) def _print_Mul(self, expr): from sympy.core.power import Pow from sympy.physics.units import Quantity include_parens = False if _coeff_isneg(expr): expr = -expr tex = "- " if expr.is_Add: tex += "(" include_parens = True else: tex = "" from sympy.simplify import fraction numer, denom = fraction(expr, exact=True) separator = self._settings['mul_symbol_latex'] numbersep = self._settings['mul_symbol_latex_numbers'] def convert(expr): if not expr.is_Mul: return str(self._print(expr)) else: _tex = last_term_tex = "" if self.order not in ('old', 'none'): args = expr.as_ordered_factors() else: args = list(expr.args) # If quantities are present append them at the back args = sorted(args, key=lambda x: isinstance(x, Quantity) or (isinstance(x, Pow) and isinstance(x.base, Quantity))) for i, term in enumerate(args): term_tex = self._print(term) if self._needs_mul_brackets(term, first=(i == 0), last=(i == len(args) - 1)): term_tex = r"\left(%s\right)" % term_tex if _between_two_numbers_p[0].search(last_term_tex) and \ _between_two_numbers_p[1].match(term_tex): # between two numbers _tex += numbersep elif _tex: _tex += separator _tex += term_tex last_term_tex = term_tex return _tex if denom is S.One and Pow(1, -1, evaluate=False) not in expr.args: # use the original expression here, since fraction() may have # altered it when producing numer and denom tex += convert(expr) else: snumer = convert(numer) sdenom = convert(denom) ldenom = len(sdenom.split()) ratio = self._settings['long_frac_ratio'] if self._settings['fold_short_frac'] \ and ldenom <= 2 and not "^" in sdenom: # handle short fractions if self._needs_mul_brackets(numer, last=False): tex += r"\left(%s\right) / %s" % (snumer, sdenom) else: tex += r"%s / %s" % (snumer, sdenom) elif ratio is not None and \ len(snumer.split()) > ratioldenom: # handle long fractions if self._needs_mul_brackets(numer, last=True): tex += r"\frac{1}{%s}%s\left(%s\right)" \ % (sdenom, separator, snumer) elif numer.is_Mul: # split a long numerator a = S.One b = S.One for x in numer.args: if self._needs_mul_brackets(x, last=False) or \ len(convert(ax).split()) > ratioldenom or \ (b.is_commutative is x.is_commutative is False): b = x else: a = x if self._needs_mul_brackets(b, last=True): tex += r"\frac{%s}{%s}%s\left(%s\right)" \ % (convert(a), sdenom, separator, convert(b)) else: tex += r"\frac{%s}{%s}%s%s" \ % (convert(a), sdenom, separator, convert(b)) else: tex += r"\frac{1}{%s}%s%s" % (sdenom, separator, snumer) else: tex += r"\frac{%s}{%s}" % (snumer, sdenom) if include_parens: tex += ")" return tex def _print_Pow(self, expr): # Treat x*Rational(1,n) as special case if expr.exp.is_Rational and abs(expr.exp.p) == 1 and expr.exp.q != 1: base = self._print(expr.base) expq = expr.exp.q if expq == 2: tex = r"\sqrt{%s}" % base elif self._settings['itex']: tex = r"\root{%d}{%s}" % (expq, base) else: tex = r"\sqrt[%d]{%s}" % (expq, base) if expr.exp.is_negative: return r"\frac{1}{%s}" % tex else: return tex elif self._settings['fold_frac_powers'] \ and expr.exp.is_Rational \ and expr.exp.q != 1: base, p, q = self.parenthesize(expr.base, PRECEDENCE['Pow']), expr.exp.p, expr.exp.q # issue #12886: add parentheses for superscripts raised to powers if '^' in base and expr.base.is_Symbol: base = r"\left(%s\right)" % base if expr.base.is_Function: return self._print(expr.base, exp="%s/%s" % (p, q)) return r"%s^{%s/%s}" % (base, p, q) elif expr.exp.is_Rational and expr.exp.is_negative and expr.base.is_commutative: # special case for 1^(-x), issue 9216 if expr.base == 1: return r"%s^{%s}" % (expr.base, expr.exp) # things like 1/x return self._print_Mul(expr) else: if expr.base.is_Function: return self._print(expr.base, exp=self._print(expr.exp)) else: tex = r"%s^{%s}" exp = self._print(expr.exp) # issue #12886: add parentheses around superscripts raised to powers base = self.parenthesize(expr.base, PRECEDENCE['Pow']) if '^' in base and expr.base.is_Symbol: base = r"\left(%s\right)" % base elif isinstance(expr.base, Derivative ) and base.startswith(r'\left(' ) and re.match(r'\\left\(\\d?d?dot', base ) and base.endswith(r'\right)'): # don't use parentheses around dotted derivative base = base[6: -7] # remove outermost added parens return tex % (base, exp) def _print_UnevaluatedExpr(self, expr): return self._print(expr.args[0]) def _print_Sum(self, expr): if len(expr.limits) == 1: tex = r"\sum_{%s=%s}^{%s} " % \ tuple([ self._print(i) for i in expr.limits[0] ]) else: def _format_ineq(l): return r"%s \leq %s \leq %s" % \ tuple([self._print(s) for s in (l[1], l[0], l[2])]) tex = r"\sum_{\substack{%s}} " % \ str.join('\\\\', [ _format_ineq(l) for l in expr.limits ]) if isinstance(expr.function, Add): tex += r"\left(%s\right)" % self._print(expr.function) else: tex += self._print(expr.function) return tex def _print_Product(self, expr): if len(expr.limits) == 1: tex = r"\prod_{%s=%s}^{%s} " % \ tuple([ self._print(i) for i in expr.limits[0] ]) else: def _format_ineq(l): return r"%s \leq %s \leq %s" % \ tuple([self._print(s) for s in (l[1], l[0], l[2])]) tex = r"\prod_{\substack{%s}} " % \ str.join('\\\\', [ _format_ineq(l) for l in expr.limits ]) if isinstance(expr.function, Add): tex += r"\left(%s\right)" % self._print(expr.function) else: tex += self._print(expr.function) return tex def _print_BasisDependent(self, expr): from sympy.vector import Vector o1 = [] if expr == expr.zero: return expr.zero._latex_form if isinstance(expr, Vector): items = expr.separate().items() else: items = [(0, expr)] for system, vect in items: inneritems = list(vect.components.items()) inneritems.sort(key = lambda x:x[0].__str__()) for k, v in inneritems: if v == 1: o1.append(' + ' + k._latex_form) elif v == -1: o1.append(' - ' + k._latex_form) else: arg_str = '(' + LatexPrinter().doprint(v) + ')' o1.append(' + ' + arg_str + k._latex_form) outstr = (''.join(o1)) if outstr[1] != '-': outstr = outstr[3:] else: outstr = outstr[1:] return outstr def _print_Indexed(self, expr): tex_base = self._print(expr.base) tex = '{'+tex_base+'}'+'_{%s}' % ','.join( map(self._print, expr.indices)) return tex def _print_IndexedBase(self, expr): return self._print(expr.label) def _print_Derivative(self, expr): if requires_partial(expr): diff_symbol = r'\partial' else: diff_symbol = r'd' tex = "" dim = 0 for x, num in reversed(expr.variable_count): dim += num if num == 1: tex += r"%s %s" % (diff_symbol, self._print(x)) else: tex += r"%s %s^{%s}" % (diff_symbol, self._print(x), num) if dim == 1: tex = r"\frac{%s}{%s}" % (diff_symbol, tex) else: tex = r"\frac{%s^{%s}}{%s}" % (diff_symbol, dim, tex) return r"%s %s" % (tex, self.parenthesize(expr.expr, PRECEDENCE["Mul"], strict=True)) def _print_Subs(self, subs): expr, old, new = subs.args latex_expr = self._print(expr) latex_old = (self._print(e) for e in old) latex_new = (self._print(e) for e in new) latex_subs = r'\\ '.join( e[0] + '=' + e[1] for e in zip(latex_old, latex_new)) return r'\left. %s \right\|_{\substack{ %s }}' % (latex_expr, latex_subs) def _print_Integral(self, expr): tex, symbols = "", [] # Only up to \iiiint exists if len(expr.limits) <= 4 and all(len(lim) == 1 for lim in expr.limits): # Use len(expr.limits)-1 so that syntax highlighters don't think # \" is an escaped quote tex = r"\i" + "i"(len(expr.limits) - 1) + "nt" symbols = [r"\, d%s" % self._print(symbol[0]) for symbol in expr.limits] else: for lim in reversed(expr.limits): symbol = lim[0] tex += r"\int" if len(lim) > 1: if self._settings['mode'] != 'inline' \ and not self._settings['itex']: tex += r"\limits" if len(lim) == 3: tex += "_{%s}^{%s}" % (self._print(lim[1]), self._print(lim[2])) if len(lim) == 2: tex += "^{%s}" % (self._print(lim[1])) symbols.insert(0, r"\, d%s" % self._print(symbol)) return r"%s %s%s" % (tex, self.parenthesize(expr.function, PRECEDENCE["Mul"], strict=True), "".join(symbols)) def _print_Limit(self, expr): e, z, z0, dir = expr.args tex = r"\lim_{%s \to " % self._print(z) if str(dir) == '+-' or z0 in (S.Infinity, S.NegativeInfinity): tex += r"%s}" % self._print(z0) else: tex += r"%s^%s}" % (self._print(z0), self._print(dir)) if isinstance(e, AssocOp): return r"%s\left(%s\right)" % (tex, self._print(e)) else: return r"%s %s" % (tex, self._print(e)) def _hprint_Function(self, func): r''' Logic to decide how to render a function to latex - if it is a recognized latex name, use the appropriate latex command - if it is a single letter, just use that letter - if it is a longer name, then put \operatorname{} around it and be mindful of undercores in the name ''' func = self._deal_with_super_sub(func) if func in accepted_latex_functions: name = r"\%s" % func elif len(func) == 1 or func.startswith('\\'): name = func else: name = r"\operatorname{%s}" % func return name def _print_Function(self, expr, exp=None): r''' Render functions to LaTeX, handling functions that LaTeX knows about e.g., sin, cos, ... by using the proper LaTeX command (\sin, \cos, ...). For single-letter function names, render them as regular LaTeX math symbols. For multi-letter function names that LaTeX does not know about, (e.g., Li, sech) use \operatorname{} so that the function name is rendered in Roman font and LaTeX handles spacing properly. expr is the expression involving the function exp is an exponent ''' func = expr.func.__name__ if hasattr(self, '_print_' + func) and \ not isinstance(expr, AppliedUndef): return getattr(self, '_print_' + func)(expr, exp) else: args = [ str(self._print(arg)) for arg in expr.args ] # How inverse trig functions should be displayed, formats are: # abbreviated: asin, full: arcsin, power: sin^-1 inv_trig_style = self._settings['inv_trig_style'] # If we are dealing with a power-style inverse trig function inv_trig_power_case = False # If it is applicable to fold the argument brackets can_fold_brackets = self._settings['fold_func_brackets'] and \ len(args) == 1 and \ not self._needs_function_brackets(expr.args[0]) inv_trig_table = ["asin", "acos", "atan", "acsc", "asec", "acot"] # If the function is an inverse trig function, handle the style if func in inv_trig_table: if inv_trig_style == "abbreviated": func = func elif inv_trig_style == "full": func = "arc" + func[1:] elif inv_trig_style == "power": func = func[1:] inv_trig_power_case = True # Can never fold brackets if we're raised to a power if exp is not None: can_fold_brackets = False if inv_trig_power_case: if func in accepted_latex_functions: name = r"\%s^{-1}" % func else: name = r"\operatorname{%s}^{-1}" % func elif exp is not None: name = r'%s^{%s}' % (self._hprint_Function(func), exp) else: name = self._hprint_Function(func) if can_fold_brackets: if func in accepted_latex_functions: # Wrap argument safely to avoid parse-time conflicts # with the function name itself name += r" {%s}" else: name += r"%s" else: name += r"{\left(%s \right)}" if inv_trig_power_case and exp is not None: name += r"^{%s}" % exp return name % ",".join(args) def _print_UndefinedFunction(self, expr): return self._hprint_Function(str(expr)) @property def _special_function_classes(self): from sympy.functions.special.tensor_functions import KroneckerDelta from sympy.functions.special.gamma_functions import gamma, lowergamma from sympy.functions.special.beta_functions import beta from sympy.functions.special.delta_functions import DiracDelta from sympy.functions.special.error_functions import Chi return {KroneckerDelta: r'\delta', gamma: r'\Gamma', lowergamma: r'\gamma', beta: r'\operatorname{B}', DiracDelta: r'\delta', Chi: r'\operatorname{Chi}'} def _print_FunctionClass(self, expr): for cls in self._special_function_classes: if issubclass(expr, cls) and expr.__name__ == cls.__name__: return self._special_function_classes[cls] return self._hprint_Function(str(expr)) def _print_Lambda(self, expr): symbols, expr = expr.args if len(symbols) == 1: symbols = self._print(symbols[0]) else: symbols = self._print(tuple(symbols)) args = (symbols, self._print(expr)) tex = r"\left( %s \mapsto %s \right)" % (symbols, self._print(expr)) return tex def _hprint_variadic_function(self, expr, exp=None): args = sorted(expr.args, key=default_sort_key) texargs = [r"%s" % self._print(symbol) for symbol in args] tex = r"\%s\left(%s\right)" % (self._print((str(expr.func)).lower()), ", ".join(texargs)) if exp is not None: return r"%s^{%s}" % (tex, exp) else: return tex _print_Min = _print_Max = _hprint_variadic_function def _print_floor(self, expr, exp=None): tex = r"\left\lfloor{%s}\right\rfloor" % self._print(expr.args[0]) if exp is not None: return r"%s^{%s}" % (tex, exp) else: return tex def _print_ceiling(self, expr, exp=None): tex = r"\left\lceil{%s}\right\rceil" % self._print(expr.args[0]) if exp is not None: return r"%s^{%s}" % (tex, exp) else: return tex def _print_log(self, expr, exp=None): if not self._settings["ln_notation"]: tex = r"\log{\left(%s \right)}" % self._print(expr.args[0]) else: tex = r"\ln{\left(%s \right)}" % self._print(expr.args[0]) if exp is not None: return r"%s^{%s}" % (tex, exp) else: return tex def _print_Abs(self, expr, exp=None): tex = r"\left\|{%s}\right\|" % self._print(expr.args[0]) if exp is not None: return r"%s^{%s}" % (tex, exp) else: return tex _print_Determinant = _print_Abs def _print_re(self, expr, exp=None): tex = r"\Re{%s}" % self.parenthesize(expr.args[0], PRECEDENCE['Atom']) return self._do_exponent(tex, exp) def _print_im(self, expr, exp=None): tex = r"\Im{%s}" % self.parenthesize(expr.args[0], PRECEDENCE['Func']) return self._do_exponent(tex, exp) def _print_Not(self, e): from sympy import Equivalent, Implies if isinstance(e.args[0], Equivalent): return self._print_Equivalent(e.args[0], r"\not\Leftrightarrow") if isinstance(e.args[0], Implies): return self._print_Implies(e.args[0], r"\not\Rightarrow") if (e.args[0].is_Boolean): return r"\neg (%s)" % self._print(e.args[0]) else: return r"\neg %s" % self._print(e.args[0]) def _print_LogOp(self, args, char): arg = args[0] if arg.is_Boolean and not arg.is_Not: tex = r"\left(%s\right)" % self._print(arg) else: tex = r"%s" % self._print(arg) for arg in args[1:]: if arg.is_Boolean and not arg.is_Not: tex += r" %s \left(%s\right)" % (char, self._print(arg)) else: tex += r" %s %s" % (char, self._print(arg)) return tex def _print_And(self, e): args = sorted(e.args, key=default_sort_key) return self._print_LogOp(args, r"\wedge") def _print_Or(self, e): args = sorted(e.args, key=default_sort_key) return self._print_LogOp(args, r"\vee") def _print_Xor(self, e): args = sorted(e.args, key=default_sort_key) return self._print_LogOp(args, r"\veebar") def _print_Implies(self, e, altchar=None): return self._print_LogOp(e.args, altchar or r"\Rightarrow") def _print_Equivalent(self, e, altchar=None): args = sorted(e.args, key=default_sort_key) return self._print_LogOp(args, altchar or r"\Leftrightarrow") def _print_conjugate(self, expr, exp=None): tex = r"\overline{%s}" % self._print(expr.args[0]) if exp is not None: return r"%s^{%s}" % (tex, exp) else: return tex def _print_polar_lift(self, expr, exp=None): func = r"\operatorname{polar\_lift}" arg = r"{\left(%s \right)}" % self._print(expr.args[0]) if exp is not None: return r"%s^{%s}%s" % (func, exp, arg) else: return r"%s%s" % (func, arg) def _print_ExpBase(self, expr, exp=None): # TODO should exp_polar be printed differently? # what about exp_polar(0), exp_polar(1)? tex = r"e^{%s}" % self._print(expr.args[0]) return self._do_exponent(tex, exp) def _print_elliptic_k(self, expr, exp=None): tex = r"\left(%s\right)" % self._print(expr.args[0]) if exp is not None: return r"K^{%s}%s" % (exp, tex) else: return r"K%s" % tex def _print_elliptic_f(self, expr, exp=None): tex = r"\left(%s\middle\| %s\right)" % \ (self._print(expr.args[0]), self._print(expr.args[1])) if exp is not None: return r"F^{%s}%s" % (exp, tex) else: return r"F%s" % tex def _print_elliptic_e(self, expr, exp=None): if len(expr.args) == 2: tex = r"\left(%s\middle\| %s\right)" % \ (self._print(expr.args[0]), self._print(expr.args[1])) else: tex = r"\left(%s\right)" % self._print(expr.args[0]) if exp is not None: return r"E^{%s}%s" % (exp, tex) else: return r"E%s" % tex def _print_elliptic_pi(self, expr, exp=None): if len(expr.args) == 3: tex = r"\left(%s; %s\middle\| %s\right)" % \ (self._print(expr.args[0]), self._print(expr.args[1]), \ self._print(expr.args[2])) else: tex = r"\left(%s\middle\| %s\right)" % \ (self._print(expr.args[0]), self._print(expr.args[1])) if exp is not None: return r"\Pi^{%s}%s" % (exp, tex) else: return r"\Pi%s" % tex def _print_beta(self, expr, exp=None): tex = r"\left(%s, %s\right)" % (self._print(expr.args[0]), self._print(expr.args[1])) if exp is not None: return r"\operatorname{B}^{%s}%s" % (exp, tex) else: return r"\operatorname{B}%s" % tex def _print_uppergamma(self, expr, exp=None): tex = r"\left(%s, %s\right)" % (self._print(expr.args[0]), self._print(expr.args[1])) if exp is not None: return r"\Gamma^{%s}%s" % (exp, tex) else: return r"\Gamma%s" % tex def _print_lowergamma(self, expr, exp=None): tex = r"\left(%s, %s\right)" % (self._print(expr.args[0]), self._print(expr.args[1])) if exp is not None: return r"\gamma^{%s}%s" % (exp, tex) else: return r"\gamma%s" % tex def _hprint_one_arg_func(self, expr, exp=None): tex = r"\left(%s\right)" % self._print(expr.args[0]) if exp is not None: return r"%s^{%s}%s" % (self._print(expr.func), exp, tex) else: return r"%s%s" % (self._print(expr.func), tex) _print_gamma = _hprint_one_arg_func def _print_Chi(self, expr, exp=None): tex = r"\left(%s\right)" % self._print(expr.args[0]) if exp is not None: return r"\operatorname{Chi}^{%s}%s" % (exp, tex) else: return r"\operatorname{Chi}%s" % tex def _print_expint(self, expr, exp=None): tex = r"\left(%s\right)" % self._print(expr.args[1]) nu = self._print(expr.args[0]) if exp is not None: return r"\operatorname{E}_{%s}^{%s}%s" % (nu, exp, tex) else: return r"\operatorname{E}_{%s}%s" % (nu, tex) def _print_fresnels(self, expr, exp=None): tex = r"\left(%s\right)" % self._print(expr.args[0]) if exp is not None: return r"S^{%s}%s" % (exp, tex) else: return r"S%s" % tex def _print_fresnelc(self, expr, exp=None): tex = r"\left(%s\right)" % self._print(expr.args[0]) if exp is not None: return r"C^{%s}%s" % (exp, tex) else: return r"C%s" % tex def _print_subfactorial(self, expr, exp=None): tex = r"!%s" % self.parenthesize(expr.args[0], PRECEDENCE["Func"]) if exp is not None: return r"%s^{%s}" % (tex, exp) else: return tex def _print_factorial(self, expr, exp=None): tex = r"%s!" % self.parenthesize(expr.args[0], PRECEDENCE["Func"]) if exp is not None: return r"%s^{%s}" % (tex, exp) else: return tex def _print_factorial2(self, expr, exp=None): tex = r"%s!!" % self.parenthesize(expr.args[0], PRECEDENCE["Func"]) if exp is not None: return r"%s^{%s}" % (tex, exp) else: return tex def _print_binomial(self, expr, exp=None): tex = r"{\binom{%s}{%s}}" % (self._print(expr.args[0]), self._print(expr.args[1])) if exp is not None: return r"%s^{%s}" % (tex, exp) else: return tex def _print_RisingFactorial(self, expr, exp=None): n, k = expr.args base = r"%s" % self.parenthesize(n, PRECEDENCE['Func']) tex = r"{%s}^{\left(%s\right)}" % (base, self._print(k)) return self._do_exponent(tex, exp) def _print_FallingFactorial(self, expr, exp=None): n, k = expr.args sub = r"%s" % self.parenthesize(k, PRECEDENCE['Func']) tex = r"{\left(%s\right)}_{%s}" % (self._print(n), sub) return self._do_exponent(tex, exp) def _hprint_BesselBase(self, expr, exp, sym): tex = r"%s" % (sym) need_exp = False if exp is not None: if tex.find('^') == -1: tex = r"%s^{%s}" % (tex, self._print(exp)) else: need_exp = True tex = r"%s_{%s}\left(%s\right)" % (tex, self._print(expr.order), self._print(expr.argument)) if need_exp: tex = self._do_exponent(tex, exp) return tex def _hprint_vec(self, vec): if len(vec) == 0: return "" s = "" for i in vec[:-1]: s += "%s, " % self._print(i) s += self._print(vec[-1]) return s def _print_besselj(self, expr, exp=None): return self._hprint_BesselBase(expr, exp, 'J') def _print_besseli(self, expr, exp=None): return self._hprint_BesselBase(expr, exp, 'I') def _print_besselk(self, expr, exp=None): return self._hprint_BesselBase(expr, exp, 'K') def _print_bessely(self, expr, exp=None): return self._hprint_BesselBase(expr, exp, 'Y') def _print_yn(self, expr, exp=None): return self._hprint_BesselBase(expr, exp, 'y') def _print_jn(self, expr, exp=None): return self._hprint_BesselBase(expr, exp, 'j') def _print_hankel1(self, expr, exp=None): return self._hprint_BesselBase(expr, exp, 'H^{(1)}') def _print_hankel2(self, expr, exp=None): return self._hprint_BesselBase(expr, exp, 'H^{(2)}') def _print_hn1(self, expr, exp=None): return self._hprint_BesselBase(expr, exp, 'h^{(1)}') def _print_hn2(self, expr, exp=None): return self._hprint_BesselBase(expr, exp, 'h^{(2)}') def _hprint_airy(self, expr, exp=None, notation=""): tex = r"\left(%s\right)" % self._print(expr.args[0]) if exp is not None: return r"%s^{%s}%s" % (notation, exp, tex) else: return r"%s%s" % (notation, tex) def _hprint_airy_prime(self, expr, exp=None, notation=""): tex = r"\left(%s\right)" % self._print(expr.args[0]) if exp is not None: return r"{%s^\prime}^{%s}%s" % (notation, exp, tex) else: return r"%s^\prime%s" % (notation, tex) def _print_airyai(self, expr, exp=None): return self._hprint_airy(expr, exp, 'Ai') def _print_airybi(self, expr, exp=None): return self._hprint_airy(expr, exp, 'Bi') def _print_airyaiprime(self, expr, exp=None): return self._hprint_airy_prime(expr, exp, 'Ai') def _print_airybiprime(self, expr, exp=None): return self._hprint_airy_prime(expr, exp, 'Bi') def _print_hyper(self, expr, exp=None): tex = r"{{}_{%s}F_{%s}\left(\begin{matrix} %s \\ %s \end{matrix}" \ r"\middle\| {%s} \right)}" % \ (self._print(len(expr.ap)), self._print(len(expr.bq)), self._hprint_vec(expr.ap), self._hprint_vec(expr.bq), self._print(expr.argument)) if exp is not None: tex = r"{%s}^{%s}" % (tex, self._print(exp)) return tex def _print_meijerg(self, expr, exp=None): tex = r"{G_{%s, %s}^{%s, %s}\left(\begin{matrix} %s & %s \\" \ r"%s & %s \end{matrix} \middle\| {%s} \right)}" % \ (self._print(len(expr.ap)), self._print(len(expr.bq)), self._print(len(expr.bm)), self._print(len(expr.an)), self._hprint_vec(expr.an), self._hprint_vec(expr.aother), self._hprint_vec(expr.bm), self._hprint_vec(expr.bother), self._print(expr.argument)) if exp is not None: tex = r"{%s}^{%s}" % (tex, self._print(exp)) return tex def _print_dirichlet_eta(self, expr, exp=None): tex = r"\left(%s\right)" % self._print(expr.args[0]) if exp is not None: return r"\eta^{%s}%s" % (self._print(exp), tex) return r"\eta%s" % tex def _print_zeta(self, expr, exp=None): if len(expr.args) == 2: tex = r"\left(%s, %s\right)" % tuple(map(self._print, expr.args)) else: tex = r"\left(%s\right)" % self._print(expr.args[0]) if exp is not None: return r"\zeta^{%s}%s" % (self._print(exp), tex) return r"\zeta%s" % tex def _print_lerchphi(self, expr, exp=None): tex = r"\left(%s, %s, %s\right)" % tuple(map(self._print, expr.args)) if exp is None: return r"\Phi%s" % tex return r"\Phi^{%s}%s" % (self._print(exp), tex) def _print_polylog(self, expr, exp=None): s, z = map(self._print, expr.args) tex = r"\left(%s\right)" % z if exp is None: return r"\operatorname{Li}_{%s}%s" % (s, tex) return r"\operatorname{Li}_{%s}^{%s}%s" % (s, self._print(exp), tex) def _print_jacobi(self, expr, exp=None): n, a, b, x = map(self._print, expr.args) tex = r"P_{%s}^{\left(%s,%s\right)}\left(%s\right)" % (n, a, b, x) if exp is not None: tex = r"\left(" + tex + r"\right)^{%s}" % (self._print(exp)) return tex def _print_gegenbauer(self, expr, exp=None): n, a, x = map(self._print, expr.args) tex = r"C_{%s}^{\left(%s\right)}\left(%s\right)" % (n, a, x) if exp is not None: tex = r"\left(" + tex + r"\right)^{%s}" % (self._print(exp)) return tex def _print_chebyshevt(self, expr, exp=None): n, x = map(self._print, expr.args) tex = r"T_{%s}\left(%s\right)" % (n, x) if exp is not None: tex = r"\left(" + tex + r"\right)^{%s}" % (self._print(exp)) return tex def _print_chebyshevu(self, expr, exp=None): n, x = map(self._print, expr.args) tex = r"U_{%s}\left(%s\right)" % (n, x) if exp is not None: tex = r"\left(" + tex + r"\right)^{%s}" % (self._print(exp)) return tex def _print_legendre(self, expr, exp=None): n, x = map(self._print, expr.args) tex = r"P_{%s}\left(%s\right)" % (n, x) if exp is not None: tex = r"\left(" + tex + r"\right)^{%s}" % (self._print(exp)) return tex def _print_assoc_legendre(self, expr, exp=None): n, a, x = map(self._print, expr.args) tex = r"P_{%s}^{\left(%s\right)}\left(%s\right)" % (n, a, x) if exp is not None: tex = r"\left(" + tex + r"\right)^{%s}" % (self._print(exp)) return tex def _print_hermite(self, expr, exp=None): n, x = map(self._print, expr.args) tex = r"H_{%s}\left(%s\right)" % (n, x) if exp is not None: tex = r"\left(" + tex + r"\right)^{%s}" % (self._print(exp)) return tex def _print_laguerre(self, expr, exp=None): n, x = map(self._print, expr.args) tex = r"L_{%s}\left(%s\right)" % (n, x) if exp is not None: tex = r"\left(" + tex + r"\right)^{%s}" % (self._print(exp)) return tex def _print_assoc_laguerre(self, expr, exp=None): n, a, x = map(self._print, expr.args) tex = r"L_{%s}^{\left(%s\right)}\left(%s\right)" % (n, a, x) if exp is not None: tex = r"\left(" + tex + r"\right)^{%s}" % (self._print(exp)) return tex def _print_Ynm(self, expr, exp=None): n, m, theta, phi = map(self._print, expr.args) tex = r"Y_{%s}^{%s}\left(%s,%s\right)" % (n, m, theta, phi) if exp is not None: tex = r"\left(" + tex + r"\right)^{%s}" % (self._print(exp)) return tex def _print_Znm(self, expr, exp=None): n, m, theta, phi = map(self._print, expr.args) tex = r"Z_{%s}^{%s}\left(%s,%s\right)" % (n, m, theta, phi) if exp is not None: tex = r"\left(" + tex + r"\right)^{%s}" % (self._print(exp)) return tex def _print_Rational(self, expr): if expr.q != 1: sign = "" p = expr.p if expr.p < 0: sign = "- " p = -p if self._settings['fold_short_frac']: return r"%s%d / %d" % (sign, p, expr.q) return r"%s\frac{%d}{%d}" % (sign, p, expr.q) else: return self._print(expr.p) def _print_Order(self, expr): s = self._print(expr.expr) if expr.point and any(p != S.Zero for p in expr.point) or \ len(expr.variables) > 1: s += '; ' if len(expr.variables) > 1: s += self._print(expr.variables) elif len(expr.variables): s += self._print(expr.variables[0]) s += r'\rightarrow ' if len(expr.point) > 1: s += self._print(expr.point) else: s += self._print(expr.point[0]) return r"O\left(%s\right)" % s def _print_Symbol(self, expr): if expr in self._settings['symbol_names']: return self._settings['symbol_names'][expr] return self._deal_with_super_sub(expr.name) if \ '\\' not in expr.name else expr.name _print_RandomSymbol = _print_Symbol _print_MatrixSymbol = _print_Symbol def _deal_with_super_sub(self, string): if '{' in string: return string name, supers, subs = split_super_sub(string) name = translate(name) supers = [translate(sup) for sup in supers] subs = [translate(sub) for sub in subs] # glue all items together: if len(supers) > 0: name += "^{%s}" % " ".join(supers) if len(subs) > 0: name += "_{%s}" % " ".join(subs) return name def _print_Relational(self, expr): if self._settings['itex']: gt = r"\gt" lt = r"\lt" else: gt = ">" lt = "<" charmap = { "==": "=", ">": gt, "<": lt, ">=": r"\geq", "<=": r"\leq", "!=": r"\neq", } return "%s %s %s" % (self._print(expr.lhs), charmap[expr.rel_op], self._print(expr.rhs)) def _print_Piecewise(self, expr): ecpairs = [r"%s & \text{for}\: %s" % (self._print(e), self._print(c)) for e, c in expr.args[:-1]] if expr.args[-1].cond == true: ecpairs.append(r"%s & \text{otherwise}" % self._print(expr.args[-1].expr)) else: ecpairs.append(r"%s & \text{for}\: %s" % (self._print(expr.args[-1].expr), self._print(expr.args[-1].cond))) tex = r"\begin{cases} %s \end{cases}" return tex % r" \\".join(ecpairs) def _print_MatrixBase(self, expr): lines = [] for line in range(expr.rows): # horrible, should be 'rows' lines.append(" & ".join([ self._print(i) for i in expr[line, :] ])) mat_str = self._settings['mat_str'] if mat_str is None: if self._settings['mode'] == 'inline': mat_str = 'smallmatrix' else: if (expr.cols <= 10) is True: mat_str = 'matrix' else: mat_str = 'array' out_str = r'\begin{%MATSTR%}%s\end{%MATSTR%}' out_str = out_str.replace('%MATSTR%', mat_str) if mat_str == 'array': out_str = out_str.replace('%s', '{' + 'c'expr.cols + '}%s') if self._settings['mat_delim']: left_delim = self._settings['mat_delim'] right_delim = self._delim_dict[left_delim] out_str = r'\left' + left_delim + out_str + \ r'\right' + right_delim return out_str % r"\\".join(lines) _print_ImmutableMatrix = _print_ImmutableDenseMatrix \ = _print_Matrix \ = _print_MatrixBase def _print_MatrixElement(self, expr): return self.parenthesize(expr.parent, PRECEDENCE["Atom"], strict=True) \ + '_{%s, %s}' % ( self._print(expr.i), self._print(expr.j) ) def _print_MatrixSlice(self, expr): def latexslice(x): x = list(x) if x[2] == 1: del x[2] if x[1] == x[0] + 1: del x[1] if x[0] == 0: x[0] = '' return ':'.join(map(self._print, x)) return (self._print(expr.parent) + r'\left[' + latexslice(expr.rowslice) + ', ' + latexslice(expr.colslice) + r'\right]') def _print_BlockMatrix(self, expr): return self._print(expr.blocks) def _print_Transpose(self, expr): mat = expr.arg from sympy.matrices import MatrixSymbol if not isinstance(mat, MatrixSymbol): return r"\left(%s\right)^T" % self._print(mat) else: return "%s^T" % self._print(mat) def _print_Trace(self, expr): mat = expr.arg return r"\mathrm{tr}\left(%s \right)" % self._print(mat) def _print_Adjoint(self, expr): mat = expr.arg from sympy.matrices import MatrixSymbol if not isinstance(mat, MatrixSymbol): return r"\left(%s\right)^\dagger" % self._print(mat) else: return r"%s^\dagger" % self._print(mat) def _print_MatMul(self, expr): from sympy import Add, MatAdd, HadamardProduct, MatMul, Mul parens = lambda x: self.parenthesize(x, precedence_traditional(expr), False) args = expr.args if isinstance(args[0], Mul): args = args[0].as_ordered_factors() + list(args[1:]) else: args = list(args) if isinstance(expr, MatMul) and _coeff_isneg(expr): if args[0] == -1: args = args[1:] else: args[0] = -args[0] return '- ' + ' '.join(map(parens, args)) else: return ' '.join(map(parens, args)) def _print_Mod(self, expr, exp=None): if exp is not None: return r'\left(%s\bmod{%s}\right)^{%s}' % (self.parenthesize(expr.args[0], PRECEDENCE['Mul'], strict=True), self._print(expr.args[1]), self._print(exp)) return r'%s\bmod{%s}' % (self.parenthesize(expr.args[0], PRECEDENCE['Mul'], strict=True), self._print(expr.args[1])) def _print_HadamardProduct(self, expr): from sympy import Add, MatAdd, MatMul def parens(x): if isinstance(x, (Add, MatAdd, MatMul)): return r"\left(%s\right)" % self._print(x) return self._print(x) return r' \circ '.join(map(parens, expr.args)) def _print_KroneckerProduct(self, expr): from sympy import Add, MatAdd, MatMul def parens(x): if isinstance(x, (Add, MatAdd, MatMul)): return r"\left(%s\right)" % self._print(x) return self._print(x) return r' \otimes '.join(map(parens, expr.args)) def _print_MatPow(self, expr): base, exp = expr.base, expr.exp from sympy.matrices import MatrixSymbol if not isinstance(base, MatrixSymbol): return r"\left(%s\right)^{%s}" % (self._print(base), self._print(exp)) else: return "%s^{%s}" % (self._print(base), self._print(exp)) def _print_ZeroMatrix(self, Z): return r"\mathbb{0}" def _print_Identity(self, I): return r"\mathbb{I}" def _print_NDimArray(self, expr): if expr.rank() == 0: return self._print(expr[()]) mat_str = self._settings['mat_str'] if mat_str is None: if self._settings['mode'] == 'inline': mat_str = 'smallmatrix' else: if (expr.rank() == 0) or (expr.shape[-1] <= 10): mat_str = 'matrix' else: mat_str = 'array' block_str = r'\begin{%MATSTR%}%s\end{%MATSTR%}' block_str = block_str.replace('%MATSTR%', mat_str) if self._settings['mat_delim']: left_delim = self._settings['mat_delim'] right_delim = self._delim_dict[left_delim] block_str = r'\left' + left_delim + block_str + \ r'\right' + right_delim if expr.rank() == 0: return block_str % "" level_str = [[]] + [[] for i in range(expr.rank())] shape_ranges = [list(range(i)) for i in expr.shape] for outer_i in itertools.product(shape_ranges): level_str[-1].append(self._print(expr[outer_i])) even = True for back_outer_i in range(expr.rank()-1, -1, -1): if len(level_str[back_outer_i+1]) < expr.shape[back_outer_i]: break if even: level_str[back_outer_i].append(r" & ".join(level_str[back_outer_i+1])) else: level_str[back_outer_i].append(block_str % (r"\\".join(level_str[back_outer_i+1]))) if len(level_str[back_outer_i+1]) == 1: level_str[back_outer_i][-1] = r"\left[" + level_str[back_outer_i][-1] + r"\right]" even = not even level_str[back_outer_i+1] = [] out_str = level_str[0][0] if expr.rank() % 2 == 1: out_str = block_str % out_str return out_str _print_ImmutableDenseNDimArray = _print_NDimArray _print_ImmutableSparseNDimArray = _print_NDimArray _print_MutableDenseNDimArray = _print_NDimArray _print_MutableSparseNDimArray = _print_NDimArray def _printer_tensor_indices(self, name, indices, index_map={}): out_str = self._print(name) last_valence = None prev_map = None for index in indices: new_valence = index.is_up if ((index in index_map) or prev_map) and last_valence == new_valence: out_str += "," if last_valence != new_valence: if last_valence is not None: out_str += "}" if index.is_up: out_str += "{}^{" else: out_str += "{}_{" out_str += self._print(index.args[0]) if index in index_map: out_str += "=" out_str += self._print(index_map[index]) prev_map = True else: prev_map = False last_valence = new_valence if last_valence is not None: out_str += "}" return out_str def _print_Tensor(self, expr): name = expr.args[0].args[0] indices = expr.get_indices() return self._printer_tensor_indices(name, indices) def _print_TensorElement(self, expr): name = expr.expr.args[0].args[0] indices = expr.expr.get_indices() index_map = expr.index_map return self._printer_tensor_indices(name, indices, index_map) def _print_TensMul(self, expr): # prints expressions like "A(a)", "3A(a)", "(1+x)A(a)" sign, args = expr._get_args_for_traditional_printer() return sign + "".join( [self.parenthesize(arg, precedence(expr)) for arg in args] ) def _print_TensAdd(self, expr): a = [] args = expr.args for x in args: a.append(self.parenthesize(x, precedence(expr))) a.sort() s = ' + '.join(a) s = s.replace('+ -', '- ') return s def _print_TensorIndex(self, expr): return "{}%s{%s}" % ( "^" if expr.is_up else "_", self._print(expr.args[0]) ) return self._print(expr.args[0]) def _print_tuple(self, expr): return r"\left( %s\right)" % \ r", \quad ".join([ self._print(i) for i in expr ]) def _print_TensorProduct(self, expr): elements = [self._print(a) for a in expr.args] return r' \otimes '.join(elements) def _print_WedgeProduct(self, expr): elements = [self._print(a) for a in expr.args] return r' \wedge '.join(elements) def _print_Tuple(self, expr): return self._print_tuple(expr) def _print_list(self, expr): return r"\left[ %s\right]" % \ r", \quad ".join([ self._print(i) for i in expr ]) def _print_dict(self, d): keys = sorted(d.keys(), key=default_sort_key) items = [] for key in keys: val = d[key] items.append("%s : %s" % (self._print(key), self._print(val))) return r"\left\{ %s\right\}" % r", \quad ".join(items) def _print_Dict(self, expr): return self._print_dict(expr) def _print_DiracDelta(self, expr, exp=None): if len(expr.args) == 1 or expr.args[1] == 0: tex = r"\delta\left(%s\right)" % self._print(expr.args[0]) else: tex = r"\delta^{\left( %s \right)}\left( %s \right)" % ( self._print(expr.args[1]), self._print(expr.args[0])) if exp: tex = r"\left(%s\right)^{%s}" % (tex, exp) return tex def _print_SingularityFunction(self, expr): shift = self._print(expr.args[0] - expr.args[1]) power = self._print(expr.args[2]) tex = r"{\left\langle %s \right\rangle}^{%s}" % (shift, power) return tex def _print_Heaviside(self, expr, exp=None): tex = r"\theta\left(%s\right)" % self._print(expr.args[0]) if exp: tex = r"\left(%s\right)^{%s}" % (tex, exp) return tex def _print_KroneckerDelta(self, expr, exp=None): i = self._print(expr.args[0]) j = self._print(expr.args[1]) if expr.args[0].is_Atom and expr.args[1].is_Atom: tex = r'\delta_{%s %s}' % (i, j) else: tex = r'\delta_{%s, %s}' % (i, j) if exp: tex = r'\left(%s\right)^{%s}' % (tex, exp) return tex def _print_LeviCivita(self, expr, exp=None): indices = map(self._print, expr.args) if all(x.is_Atom for x in expr.args): tex = r'\varepsilon_{%s}' % " ".join(indices) else: tex = r'\varepsilon_{%s}' % ", ".join(indices) if exp: tex = r'\left(%s\right)^{%s}' % (tex, exp) return tex def _print_ProductSet(self, p): if len(p.sets) > 1 and not has_variety(p.sets): return self._print(p.sets[0]) + "^{%d}" % len(p.sets) else: return r" \times ".join(self._print(set) for set in p.sets) def _print_RandomDomain(self, d): if hasattr(d, 'as_boolean'): return 'Domain: ' + self._print(d.as_boolean()) elif hasattr(d, 'set'): return ('Domain: ' + self._print(d.symbols) + ' in ' + self._print(d.set)) elif hasattr(d, 'symbols'): return 'Domain on ' + self._print(d.symbols) else: return self._print(None) def _print_FiniteSet(self, s): items = sorted(s.args, key=default_sort_key) return self._print_set(items) def _print_set(self, s): items = sorted(s, key=default_sort_key) items = ", ".join(map(self._print, items)) return r"\left\{%s\right\}" % items _print_frozenset = _print_set def _print_Range(self, s): dots = r'\ldots' if s.start.is_infinite: printset = s.start, dots, s[-1] - s.step, s[-1] elif s.stop.is_infinite or len(s) > 4: it = iter(s) printset = next(it), next(it), dots, s[-1] else: printset = tuple(s) return (r"\left\{" + r", ".join(self._print(el) for el in printset) + r"\right\}") def _print_SeqFormula(self, s): if s.start is S.NegativeInfinity: stop = s.stop printset = (r'\ldots', s.coeff(stop - 3), s.coeff(stop - 2), s.coeff(stop - 1), s.coeff(stop)) elif s.stop is S.Infinity or s.length > 4: printset = s[:4] printset.append(r'\ldots') else: printset = tuple(s) return (r"\left[" + r", ".join(self._print(el) for el in printset) + r"\right]") _print_SeqPer = _print_SeqFormula _print_SeqAdd = _print_SeqFormula _print_SeqMul = _print_SeqFormula def _print_Interval(self, i): if i.start == i.end: return r"\left\{%s\right\}" % self._print(i.start) else: if i.left_open: left = '(' else: left = '[' if i.right_open: right = ')' else: right = ']' return r"\left%s%s, %s\right%s" % \ (left, self._print(i.start), self._print(i.end), right) def _print_AccumulationBounds(self, i): return r"\left\langle %s, %s\right\rangle" % \ (self._print(i.min), self._print(i.max)) def _print_Union(self, u): return r" \cup ".join([self._print(i) for i in u.args]) def _print_Complement(self, u): return r" \setminus ".join([self._print(i) for i in u.args]) def _print_Intersection(self, u): return r" \cap ".join([self._print(i) for i in u.args]) def _print_SymmetricDifference(self, u): return r" \triangle ".join([self._print(i) for i in u.args]) def _print_EmptySet(self, e): return r"\emptyset" def _print_Naturals(self, n): return r"\mathbb{N}" def _print_Naturals0(self, n): return r"\mathbb{N}_0" def _print_Integers(self, i): return r"\mathbb{Z}" def _print_Reals(self, i): return r"\mathbb{R}" def _print_Complexes(self, i): return r"\mathbb{C}" def _print_ImageSet(self, s): sets = s.args[1:] varsets = [r"%s \in %s" % (self._print(var), self._print(setv)) for var, setv in zip(s.lamda.variables, sets)] return r"\left\{%s\; \|\; %s\right\}" % ( self._print(s.lamda.expr), ', '.join(varsets)) def _print_ConditionSet(self, s): vars_print = ', '.join([self._print(var) for var in Tuple(s.sym)]) if s.base_set is S.UniversalSet: return r"\left\{%s \mid %s \right\}" % ( vars_print, self._print(s.condition.as_expr())) return r"\left\{%s \mid %s \in %s \wedge %s \right\}" % ( vars_print, vars_print, self._print(s.base_set), self._print(s.condition.as_expr())) def _print_ComplexRegion(self, s): vars_print = ', '.join([self._print(var) for var in s.variables]) return r"\left\{%s\; \|\; %s \in %s \right\}" % ( self._print(s.expr), vars_print, self._print(s.sets)) def _print_Contains(self, e): return r"%s \in %s" % tuple(self._print(a) for a in e.args) def _print_FourierSeries(self, s): return self._print_Add(s.truncate()) + self._print(r' + \ldots') def _print_FormalPowerSeries(self, s): return self._print_Add(s.infinite) def _print_FiniteField(self, expr): return r"\mathbb{F}_{%s}" % expr.mod def _print_IntegerRing(self, expr): return r"\mathbb{Z}" def _print_RationalField(self, expr): return r"\mathbb{Q}" def _print_RealField(self, expr): return r"\mathbb{R}" def _print_ComplexField(self, expr): return r"\mathbb{C}" def _print_PolynomialRing(self, expr): domain = self._print(expr.domain) symbols = ", ".join(map(self._print, expr.symbols)) return r"%s\left[%s\right]" % (domain, symbols) def _print_FractionField(self, expr): domain = self._print(expr.domain) symbols = ", ".join(map(self._print, expr.symbols)) return r"%s\left(%s\right)" % (domain, symbols) def _print_PolynomialRingBase(self, expr): domain = self._print(expr.domain) symbols = ", ".join(map(self._print, expr.symbols)) inv = "" if not expr.is_Poly: inv = r"S_<^{-1}" return r"%s%s\left[%s\right]" % (inv, domain, symbols) def _print_Poly(self, poly): cls = poly.__class__.__name__ terms = [] for monom, coeff in poly.terms(): s_monom = '' for i, exp in enumerate(monom): if exp > 0: if exp == 1: s_monom += self._print(poly.gens[i]) else: s_monom += self._print(pow(poly.gens[i], exp)) if coeff.is_Add: if s_monom: s_coeff = r"\left(%s\right)" % self._print(coeff) else: s_coeff = self._print(coeff) else: if s_monom: if coeff is S.One: terms.extend(['+', s_monom]) continue if coeff is S.NegativeOne: terms.extend(['-', s_monom]) continue s_coeff = self._print(coeff) if not s_monom: s_term = s_coeff else: s_term = s_coeff + " " + s_monom if s_term.startswith('-'): terms.extend(['-', s_term[1:]]) else: terms.extend(['+', s_term]) if terms[0] in ['-', '+']: modifier = terms.pop(0) if modifier == '-': terms[0] = '-' + terms[0] expr = ' '.join(terms) gens = list(map(self._print, poly.gens)) domain = "domain=%s" % self._print(poly.get_domain()) args = ", ".join([expr] + gens + [domain]) if cls in accepted_latex_functions: tex = r"\%s {\left(%s \right)}" % (cls, args) else: tex = r"\operatorname{%s}{\left( %s \right)}" % (cls, args) return tex def _print_ComplexRootOf(self, root): cls = root.__class__.__name__ if cls == "ComplexRootOf": cls = "CRootOf" expr = self._print(root.expr) index = root.index if cls in accepted_latex_functions: return r"\%s {\left(%s, %d\right)}" % (cls, expr, index) else: return r"\operatorname{%s} {\left(%s, %d\right)}" % (cls, expr, index) def _print_RootSum(self, expr): cls = expr.__class__.__name__ args = [self._print(expr.expr)] if expr.fun is not S.IdentityFunction: args.append(self._print(expr.fun)) if cls in accepted_latex_functions: return r"\%s {\left(%s\right)}" % (cls, ", ".join(args)) else: return r"\operatorname{%s} {\left(%s\right)}" % (cls, ", ".join(args)) def _print_PolyElement(self, poly): mul_symbol = self._settings['mul_symbol_latex'] return poly.str(self, PRECEDENCE, "{%s}^{%d}", mul_symbol) def _print_FracElement(self, frac): if frac.denom == 1: return self._print(frac.numer) else: numer = self._print(frac.numer) denom = self._print(frac.denom) return r"\frac{%s}{%s}" % (numer, denom) def _print_euler(self, expr, exp=None): m, x = (expr.args[0], None) if len(expr.args) == 1 else expr.args tex = r"E_{%s}" % self._print(m) if exp is not None: tex = r"%s^{%s}" % (tex, self._print(exp)) if x is not None: tex = r"%s\left(%s\right)" % (tex, self._print(x)) return tex def _print_catalan(self, expr, exp=None): tex = r"C_{%s}" % self._print(expr.args[0]) if exp is not None: tex = r"%s^{%s}" % (tex, self._print(exp)) return tex def _print_MellinTransform(self, expr): return r"\mathcal{M}_{%s}\left[%s\right]\left(%s\right)" % (self._print(expr.args[1]), self._print(expr.args[0]), self._print(expr.args[2])) def _print_InverseMellinTransform(self, expr): return r"\mathcal{M}^{-1}_{%s}\left[%s\right]\left(%s\right)" % (self._print(expr.args[1]), self._print(expr.args[0]), self._print(expr.args[2])) def _print_LaplaceTransform(self, expr): return r"\mathcal{L}_{%s}\left[%s\right]\left(%s\right)" % (self._print(expr.args[1]), self._print(expr.args[0]), self._print(expr.args[2])) def _print_InverseLaplaceTransform(self, expr): return r"\mathcal{L}^{-1}_{%s}\left[%s\right]\left(%s\right)" % (self._print(expr.args[1]), self._print(expr.args[0]), self._print(expr.args[2])) def _print_FourierTransform(self, expr): return r"\mathcal{F}_{%s}\left[%s\right]\left(%s\right)" % (self._print(expr.args[1]), self._print(expr.args[0]), self._print(expr.args[2])) def _print_InverseFourierTransform(self, expr): return r"\mathcal{F}^{-1}_{%s}\left[%s\right]\left(%s\right)" % (self._print(expr.args[1]), self._print(expr.args[0]), self._print(expr.args[2])) def _print_SineTransform(self, expr): return r"\mathcal{SIN}_{%s}\left[%s\right]\left(%s\right)" % (self._print(expr.args[1]), self._print(expr.args[0]), self._print(expr.args[2])) def _print_InverseSineTransform(self, expr): return r"\mathcal{SIN}^{-1}_{%s}\left[%s\right]\left(%s\right)" % (self._print(expr.args[1]), self._print(expr.args[0]), self._print(expr.args[2])) def _print_CosineTransform(self, expr): return r"\mathcal{COS}_{%s}\left[%s\right]\left(%s\right)" % (self._print(expr.args[1]), self._print(expr.args[0]), self._print(expr.args[2])) def _print_InverseCosineTransform(self, expr): return r"\mathcal{COS}^{-1}_{%s}\left[%s\right]\left(%s\right)" % (self._print(expr.args[1]), self._print(expr.args[0]), self._print(expr.args[2])) def _print_DMP(self, p): try: if p.ring is not None: # TODO incorporate order return self._print(p.ring.to_sympy(p)) except SympifyError: pass return self._print(repr(p)) def _print_DMF(self, p): return self._print_DMP(p) def _print_Object(self, object): return self._print(Symbol(object.name)) def _print_Morphism(self, morphism): domain = self._print(morphism.domain) codomain = self._print(morphism.codomain) return "%s\\rightarrow %s" % (domain, codomain) def _print_NamedMorphism(self, morphism): pretty_name = self._print(Symbol(morphism.name)) pretty_morphism = self._print_Morphism(morphism) return "%s:%s" % (pretty_name, pretty_morphism) def _print_IdentityMorphism(self, morphism): from sympy.categories import NamedMorphism return self._print_NamedMorphism(NamedMorphism( morphism.domain, morphism.codomain, "id")) def _print_CompositeMorphism(self, morphism): # All components of the morphism have names and it is thus # possible to build the name of the composite. component_names_list = [self._print(Symbol(component.name)) for component in morphism.components] component_names_list.reverse() component_names = "\\circ ".join(component_names_list) + ":" pretty_morphism = self._print_Morphism(morphism) return component_names + pretty_morphism def _print_Category(self, morphism): return "\\mathbf{%s}" % self._print(Symbol(morphism.name)) def _print_Diagram(self, diagram): if not diagram.premises: # This is an empty diagram. return self._print(S.EmptySet) latex_result = self._print(diagram.premises) if diagram.conclusions: latex_result += "\\Longrightarrow %s" % \ self._print(diagram.conclusions) return latex_result def _print_DiagramGrid(self, grid): latex_result = "\\begin{array}{%s}\n" % ("c" * grid.width) for i in range(grid.height): for j in range(grid.width): if grid[i, j]: latex_result += latex(grid[i, j]) latex_result += " " if j != grid.width - 1: latex_result += "& " if i != grid.height - 1: latex_result += "\\\\" latex_result += "\n" latex_result += "\\end{array}\n" return latex_result def _print_FreeModule(self, M): return '{%s}^{%s}' % (self._print(M.ring), self._print(M.rank)) def _print_FreeModuleElement(self, m): # Print as row vector for convenience, for now. return r"\left[ %s \right]" % ",".join( '{' + self._print(x) + '}' for x in m) def _print_SubModule(self, m): return r"\left\langle %s \right\rangle" % ",".join( '{' + self._print(x) + '}' for x in m.gens) def _print_ModuleImplementedIdeal(self, m): return r"\left\langle %s \right\rangle" % ",".join( '{' + self._print(x) + '}' for [x] in m._module.gens) def _print_Quaternion(self, expr): # TODO: This expression is potentially confusing, # shall we print it as `Quaternion( ... )`? s = [self.parenthesize(i, PRECEDENCE["Mul"], strict=True) for i in expr.args] a = [s[0]] + [i+" "+j for i, j in zip(s[1:], "ijk")] return " + ".join(a) def _print_QuotientRing(self, R): # TODO nicer fractions for few generators... return r"\frac{%s}{%s}" % (self._print(R.ring), self._print(R.base_ideal)) def _print_QuotientRingElement(self, x): return r"{%s} + {%s}" % (self._print(x.data), self._print(x.ring.base_ideal)) def _print_QuotientModuleElement(self, m): return r"{%s} + {%s}" % (self._print(m.data), self._print(m.module.killed_module)) def _print_QuotientModule(self, M): # TODO nicer fractions for few generators... return r"\frac{%s}{%s}" % (self._print(M.base), self._print(M.killed_module)) def _print_MatrixHomomorphism(self, h): return r"{%s} : {%s} \to {%s}" % (self._print(h._sympy_matrix()), self._print(h.domain), self._print(h.codomain)) def _print_BaseScalarField(self, field): string = field._coord_sys._names[field._index] return r'\boldsymbol{\mathrm{%s}}' % self._print(Symbol(string)) def _print_BaseVectorField(self, field): string = field._coord_sys._names[field._index] return r'\partial_{%s}' % self._print(Symbol(string)) def _print_Differential(self, diff): field = diff._form_field if hasattr(field, '_coord_sys'): string = field._coord_sys._names[field._index] return r'\mathrm{d}%s' % self._print(Symbol(string)) else: return 'd(%s)' % self._print(field) string = self._print(field) return r'\mathrm{d}\left(%s\right)' % string def _print_Tr(self, p): #Todo: Handle indices contents = self._print(p.args[0]) return r'\mbox{Tr}\left(%s\right)' % (contents) def _print_totient(self, expr, exp=None): if exp is not None: return r'\left(\phi\left(%s\right)\right)^{%s}' % (self._print(expr.args[0]), self._print(exp)) return r'\phi\left(%s\right)' % self._print(expr.args[0]) def _print_reduced_totient(self, expr, exp=None): if exp is not None: return r'\left(\lambda\left(%s\right)\right)^{%s}' % (self._print(expr.args[0]), self._print(exp)) return r'\lambda\left(%s\right)' % self._print(expr.args[0]) def _print_divisor_sigma(self, expr, exp=None): if len(expr.args) == 2: tex = r"_%s\left(%s\right)" % tuple(map(self._print, (expr.args[1], expr.args[0]))) else: tex = r"\left(%s\right)" % self._print(expr.args[0]) if exp is not None: return r"\sigma^{%s}%s" % (self._print(exp), tex) return r"\sigma%s" % tex def _print_udivisor_sigma(self, expr, exp=None): if len(expr.args) == 2: tex = r"_%s\left(%s\right)" % tuple(map(self._print, (expr.args[1], expr.args[0]))) else: tex = r"\left(%s\right)" % self._print(expr.args[0]) if exp is not None: return r"\sigma^^{%s}%s" % (self._print(exp), tex) return r"\sigma^%s" % tex def _print_primenu(self, expr, exp=None): if exp is not None: return r'\left(\nu\left(%s\right)\right)^{%s}' % (self._print(expr.args[0]), self._print(exp)) return r'\nu\left(%s\right)' % self._print(expr.args[0]) def _print_primeomega(self, expr, exp=None): if exp is not None: return r'\left(\Omega\left(%s\right)\right)^{%s}' % (self._print(expr.args[0]), self._print(exp)) return r'\Omega\left(%s\right)' % self._print(expr.args[0]) def translate(s): r''' Check for a modifier ending the string. If present, convert the modifier to latex and translate the rest recursively. Given a description of a Greek letter or other special character, return the appropriate latex. Let everything else pass as given. >>> from sympy.printing.latex import translate >>> translate('alphahatdotprime') "{\\dot{\\hat{\\alpha}}}'" ''' # Process the rest tex = tex_greek_dictionary.get(s) if tex: return tex elif s.lower() in greek_letters_set: return "\\" + s.lower() elif s in other_symbols: return "\\" + s else: # Process modifiers, if any, and recurse for key in sorted(modifier_dict.keys(), key=lambda k:len(k), reverse=True): if s.lower().endswith(key) and len(s)>len(key): return modifier_dict[key](translate(s[:-len(key)])) return s def latex(expr, fold_frac_powers=False, fold_func_brackets=False, fold_short_frac=None, inv_trig_style="abbreviated", itex=False, ln_notation=False, long_frac_ratio=None, mat_delim="[", mat_str=None, mode="plain", mul_symbol=None, order=None, symbol_names=None): r"""Convert the given expression to LaTeX string representation. Parameters ========== fold_frac_powers : boolean, optional Emit ``^{p/q}`` instead of ``^{\frac{p}{q}}`` for fractional powers. fold_func_brackets : boolean, optional Fold function brackets where applicable. fold_short_frac : boolean, optional Emit ``p / q`` instead of ``\frac{p}{q}`` when the denominator is simple enough (at most two terms and no powers). The default value is ``True`` for inline mode, ``False`` otherwise. inv_trig_style : string, optional How inverse trig functions should be displayed. Can be one of ``abbreviated``, ``full``, or ``power``. Defaults to ``abbreviated``. itex : boolean, optional Specifies if itex-specific syntax is used, including emitting ``$$...$$``. ln_notation : boolean, optional If set to ``True``, ``\ln`` is used instead of default ``\log``. long_frac_ratio : float or None, optional The allowed ratio of the width of the numerator to the width of the denominator before the printer breaks off long fractions. If ``None`` (the default value), long fractions are not broken up. mat_delim : string, optional The delimiter to wrap around matrices. Can be one of ``[``, ``(``, or the empty string. Defaults to ``[``. mat_str : string, optional Which matrix environment string to emit. ``smallmatrix``, ``matrix``, ``array``, etc. Defaults to ``smallmatrix`` for inline mode, ``matrix`` for matrices of no more than 10 columns, and ``array`` otherwise. mode: string, optional Specifies how the generated code will be delimited. ``mode`` can be one of ``plain``, ``inline``, ``equation`` or ``equation``. If ``mode`` is set to ``plain``, then the resulting code will not be delimited at all (this is the default). If ``mode`` is set to ``inline`` then inline LaTeX ``$...$`` will be used. If ``mode`` is set to ``equation`` or ``equation``, the resulting code will be enclosed in the ``equation`` or ``equation`` environment (remember to import ``amsmath`` for ``equation``), unless the ``itex`` option is set. In the latter case, the ``$$...$$`` syntax is used. mul_symbol : string or None, optional The symbol to use for multiplication. Can be one of ``None``, ``ldot``, ``dot``, or ``times``. order: string, optional Any of the supported monomial orderings (currently ``lex``, ``grlex``, or ``grevlex``), ``old``, and ``none``. This parameter does nothing for Mul objects. Setting order to ``old`` uses the compatibility ordering for Add defined in Printer. For very large expressions, set the ``order`` keyword to ``none`` if speed is a concern. symbol_names : dictionary of strings mapped to symbols, optional Dictionary of symbols and the custom strings they should be emitted as. Notes ===== Not using a print statement for printing, results in double backslashes for latex commands since that's the way Python escapes backslashes in strings. >>> from sympy import latex, Rational >>> from sympy.abc import tau >>> latex((2tau)Rational(7,2)) '8 \\sqrt{2} \\tau^{\\frac{7}{2}}' >>> print(latex((2tau)*Rational(7,2))) 8 \sqrt{2} \tau^{\frac{7}{2}} Examples ======== >>> from sympy import latex, pi, sin, asin, Integral, Matrix, Rational, log >>> from sympy.abc import x, y, mu, r, tau Basic usage: >>> print(latex((2tau)*Rational(7,2))) 8 \sqrt{2} \tau^{\frac{7}{2}} ``mode`` and ``itex`` options: >>> print(latex((2mu)*Rational(7,2), mode='plain')) 8 \sqrt{2} \mu^{\frac{7}{2}} >>> print(latex((2tau)*Rational(7,2), mode='inline')) $8 \sqrt{2} \tau^{7 / 2}$ >>> print(latex((2mu)*Rational(7,2), mode='equation')) \begin{equation}8 \sqrt{2} \mu^{\frac{7}{2}}\end{equation} >>> print(latex((2mu)Rational(7,2), mode='equation')) \begin{equation}8 \sqrt{2} \mu^{\frac{7}{2}}\end{equation} >>> print(latex((2mu)*Rational(7,2), mode='equation', itex=True)) $$8 \sqrt{2} \mu^{\frac{7}{2}}$$ >>> print(latex((2mu)*Rational(7,2), mode='plain')) 8 \sqrt{2} \mu^{\frac{7}{2}} >>> print(latex((2tau)*Rational(7,2), mode='inline')) $8 \sqrt{2} \tau^{7 / 2}$ >>> print(latex((2mu)*Rational(7,2), mode='equation')) \begin{equation}8 \sqrt{2} \mu^{\frac{7}{2}}\end{equation} >>> print(latex((2mu)Rational(7,2), mode='equation')) \begin{equation}8 \sqrt{2} \mu^{\frac{7}{2}}\end{equation} >>> print(latex((2mu)*Rational(7,2), mode='equation', itex=True)) $$8 \sqrt{2} \mu^{\frac{7}{2}}$$ Fraction options: >>> print(latex((2tau)*Rational(7,2), fold_frac_powers=True)) 8 \sqrt{2} \tau^{7/2} >>> print(latex((2tau)*sin(Rational(7,2)))) \left(2 \tau\right)^{\sin{\left(\frac{7}{2} \right)}} >>> print(latex((2tau)*sin(Rational(7,2)), fold_func_brackets=True)) \left(2 \tau\right)^{\sin {\frac{7}{2}}} >>> print(latex(3x*2/y)) \frac{3 x^{2}}{y} >>> print(latex(3x*2/y, fold_short_frac=True)) 3 x^{2} / y >>> print(latex(Integral(r, r)/2/pi, long_frac_ratio=2)) \frac{\int r\, dr}{2 \pi} >>> print(latex(Integral(r, r)/2/pi, long_frac_ratio=0)) \frac{1}{2 \pi} \int r\, dr Multiplication options: >>> print(latex((2tau)sin(Rational(7,2)), mul_symbol="times")) \left(2 \times \tau\right)^{\sin{\left(\frac{7}{2} \right)}} Trig options: >>> print(latex(asin(Rational(7,2)))) \operatorname{asin}{\left(\frac{7}{2} \right)} >>> print(latex(asin(Rational(7,2)), inv_trig_style="full")) \arcsin{\left(\frac{7}{2} \right)} >>> print(latex(asin(Rational(7,2)), inv_trig_style="power")) \sin^{-1}{\left(\frac{7}{2} \right)} Matrix options: >>> print(latex(Matrix(2, 1, [x, y]))) \left[\begin{matrix}x\\y\end{matrix}\right] >>> print(latex(Matrix(2, 1, [x, y]), mat_str = "array")) \left[\begin{array}{c}x\\y\end{array}\right] >>> print(latex(Matrix(2, 1, [x, y]), mat_delim="(")) \left(\begin{matrix}x\\y\end{matrix}\right) Custom printing of symbols: >>> print(latex(x2, symbol_names={x: 'x_i'})) x_i^{2} Logarithms: >>> print(latex(log(10))) \log{\left(10 \right)} >>> print(latex(log(10), ln_notation=True)) \ln{\left(10 \right)} ``latex()`` also supports the builtin container types list, tuple, and dictionary. >>> print(latex([2/x, y], mode='inline')) $\left[ 2 / x, \quad y\right]$ """ if symbol_names is None: symbol_names = {} settings = { 'fold_frac_powers' : fold_frac_powers, 'fold_func_brackets' : fold_func_brackets, 'fold_short_frac' : fold_short_frac, 'inv_trig_style' : inv_trig_style, 'itex' : itex, 'ln_notation' : ln_notation, 'long_frac_ratio' : long_frac_ratio, 'mat_delim' : mat_delim, 'mat_str' : mat_str, 'mode' : mode, 'mul_symbol' : mul_symbol, 'order' : order, 'symbol_names' : symbol_names, } return LatexPrinter(settings).doprint(expr) def print_latex(expr, settings): """Prints LaTeX representation of the given expression. Takes the same settings as ``latex()``.""" print(latex(expr, settings))
854361b66bcf591a98bb01b662400db6ddf75a2ea64fe32c564cfe06422c4079	"""Printing subsystem driver SymPy's printing system works the following way: Any expression can be passed to a designated Printer who then is responsible to return an adequate representation of that expression. The basic concept is the following: 1. Let the object print itself if it knows how. 2. Take the best fitting method defined in the printer. 3. As fall-back use the emptyPrinter method for the printer. Which Method is Responsible for Printing? ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ The whole printing process is started by calling ``.doprint(expr)`` on the printer which you want to use. This method looks for an appropriate method which can print the given expression in the given style that the printer defines. While looking for the method, it follows these steps: 1. Let the object print itself if it knows how. The printer looks for a specific method in every object. The name of that method depends on the specific printer and is defined under ``Printer.printmethod``. For example, StrPrinter calls ``_sympystr`` and LatexPrinter calls ``_latex``. Look at the documentation of the printer that you want to use. The name of the method is specified there. This was the original way of doing printing in sympy. Every class had its own latex, mathml, str and repr methods, but it turned out that it is hard to produce a high quality printer, if all the methods are spread out that far. Therefore all printing code was combined into the different printers, which works great for built-in sympy objects, but not that good for user defined classes where it is inconvenient to patch the printers. 2. Take the best fitting method defined in the printer. The printer loops through expr classes (class + its bases), and tries to dispatch the work to ``_print_<EXPR_CLASS>`` e.g., suppose we have the following class hierarchy:: Basic \| Atom \| Number \| Rational then, for ``expr=Rational(...)``, the Printer will try to call printer methods in the order as shown in the figure below:: p._print(expr) \| \|-- p._print_Rational(expr) \| \|-- p._print_Number(expr) \| \|-- p._print_Atom(expr) \| `-- p._print_Basic(expr) if ``._print_Rational`` method exists in the printer, then it is called, and the result is returned back. Otherwise, the printer tries to call ``._print_Number`` and so on. 3. As a fall-back use the emptyPrinter method for the printer. As fall-back ``self.emptyPrinter`` will be called with the expression. If not defined in the Printer subclass this will be the same as ``str(expr)``. Example of Custom Printer ^^^^^^^^^^^^^^^^^^^^^^^^^ .. _printer_example: In the example below, we have a printer which prints the derivative of a function in a shorter form. .. code-block:: python from sympy import Symbol from sympy.printing.latex import LatexPrinter, print_latex from sympy.core.function import UndefinedFunction, Function class MyLatexPrinter(LatexPrinter): \"\"\"Print derivative of a function of symbols in a shorter form. \"\"\" def _print_Derivative(self, expr): function, vars = expr.args if not isinstance(type(function), UndefinedFunction) or \\ not all(isinstance(i, Symbol) for i in vars): return super()._print_Derivative(expr) # If you want the printer to work correctly for nested # expressions then use self._print() instead of str() or latex(). # See the example of nested modulo below in the custom printing # method section. return "{}_{{{}}}".format( self._print(Symbol(function.func.__name__)), ''.join(self._print(i) for i in vars)) def print_my_latex(expr): \"\"\" Most of the printers define their own wrappers for print(). These wrappers usually take printer settings. Our printer does not have any settings. \"\"\" print(MyLatexPrinter().doprint(expr)) y = Symbol("y") x = Symbol("x") f = Function("f") expr = f(x, y).diff(x, y) # Print the expression using the normal latex printer and our custom # printer. print_latex(expr) print_my_latex(expr) The output of the code above is:: \\frac{\\partial^{2}}{\\partial x\\partial y} f{\\left(x,y \\right)} f_{xy} Example of Custom Printing Method ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ In the example below, the latex printing of the modulo operator is modified. This is done by overriding the method ``_latex`` of ``Mod``. .. code-block:: python from sympy import Symbol, Mod, Integer from sympy.printing.latex import print_latex class ModOp(Mod): def _latex(self, printer=None): # Always use printer.doprint() otherwise nested expressions won't # work. See the example of ModOpWrong. a, b = [printer.doprint(i) for i in self.args] return r"\\operatorname{Mod}{\\left( %s,%s \\right)}" % (a,b) class ModOpWrong(Mod): def _latex(self, printer=None): a, b = [str(i) for i in self.args] return r"\\operatorname{Mod}{\\left( %s,%s \\right)}" % (a,b) x = Symbol('x') m = Symbol('m') print_latex(ModOp(x, m)) print_latex(Mod(x, m)) # Nested modulo. print_latex(ModOp(ModOp(x, m), Integer(7))) print_latex(ModOpWrong(ModOpWrong(x, m), Integer(7))) The output of the code above is:: \\operatorname{Mod}{\\left( x,m \\right)} x\\bmod{m} \\operatorname{Mod}{\\left( \\operatorname{Mod}{\\left( x,m \\right)},7 \\right)} \\operatorname{Mod}{\\left( ModOpWrong(x, m),7 \\right)} """ from __future__ import print_function, division from contextlib import contextmanager from sympy import Basic, Add from sympy.core.core import BasicMeta from sympy.core.function import AppliedUndef, UndefinedFunction, Function from functools import cmp_to_key @contextmanager def printer_context(printer, kwargs): original = printer._context.copy() try: printer._context.update(kwargs) yield finally: printer._context = original class Printer(object): """ Generic printer Its job is to provide infrastructure for implementing new printers easily. If you want to define your custom Printer or your custom printing method for your custom class then see the example above: printer_example_ . """ _global_settings = {} _default_settings = {} emptyPrinter = str printmethod = None def __init__(self, settings=None): self._str = str self._settings = self._default_settings.copy() self._context = dict() # mutable during printing for key, val in self._global_settings.items(): if key in self._default_settings: self._settings[key] = val if settings is not None: self._settings.update(settings) if len(self._settings) > len(self._default_settings): for key in self._settings: if key not in self._default_settings: raise TypeError("Unknown setting '%s'." % key) # _print_level is the number of times self._print() was recursively # called. See StrPrinter._print_Float() for an example of usage self._print_level = 0 @classmethod def set_global_settings(cls, settings): """Set system-wide printing settings. """ for key, val in settings.items(): if val is not None: cls._global_settings[key] = val @property def order(self): if 'order' in self._settings: return self._settings['order'] else: raise AttributeError("No order defined.") def doprint(self, expr): """Returns printer's representation for expr (as a string)""" return self._str(self._print(expr)) def _print(self, expr, kwargs): """Internal dispatcher Tries the following concepts to print an expression: 1. Let the object print itself if it knows how. 2. Take the best fitting method defined in the printer. 3. As fall-back use the emptyPrinter method for the printer. """ self._print_level += 1 try: # If the printer defines a name for a printing method # (Printer.printmethod) and the object knows for itself how it # should be printed, use that method. if (self.printmethod and hasattr(expr, self.printmethod) and not isinstance(expr, BasicMeta)): return getattr(expr, self.printmethod)(self, kwargs) # See if the class of expr is known, or if one of its super # classes is known, and use that print function # Exception: ignore the subclasses of Undefined, so that, e.g., # Function('gamma') does not get dispatched to _print_gamma classes = type(expr).__mro__ if AppliedUndef in classes: classes = classes[classes.index(AppliedUndef):] if UndefinedFunction in classes: classes = classes[classes.index(UndefinedFunction):] # Another exception: if someone subclasses a known function, e.g., # gamma, and changes the name, then ignore _print_gamma if Function in classes: i = classes.index(Function) classes = tuple(c for c in classes[:i] if \ c.__name__ == classes[0].__name__ or \ c.__name__.endswith("Base")) + classes[i:] for cls in classes: printmethod = '_print_' + cls.__name__ if hasattr(self, printmethod): return getattr(self, printmethod)(expr, *kwargs) # Unknown object, fall back to the emptyPrinter. return self.emptyPrinter(expr) finally: self._print_level -= 1 def _as_ordered_terms(self, expr, order=None): """A compatibility function for ordering terms in Add. """ order = order or self.order if order == 'old': return sorted(Add.make_args(expr), key=cmp_to_key(Basic._compare_pretty)) else: return expr.as_ordered_terms(order=order)
6b39546502b137419017de8d909a56a5ab00a980e7cd9f117ce8a62fb3735607	""" Mathematica code printer """ from __future__ import print_function, division from sympy.printing.codeprinter import CodePrinter from sympy.printing.str import StrPrinter from sympy.printing.precedence import precedence # Used in MCodePrinter._print_Function(self) known_functions = { "exp": [(lambda x: True, "Exp")], "log": [(lambda x: True, "Log")], "sin": [(lambda x: True, "Sin")], "cos": [(lambda x: True, "Cos")], "tan": [(lambda x: True, "Tan")], "cot": [(lambda x: True, "Cot")], "asin": [(lambda x: True, "ArcSin")], "acos": [(lambda x: True, "ArcCos")], "atan": [(lambda x: True, "ArcTan")], "sinh": [(lambda x: True, "Sinh")], "cosh": [(lambda x: True, "Cosh")], "tanh": [(lambda x: True, "Tanh")], "coth": [(lambda x: True, "Coth")], "sech": [(lambda x: True, "Sech")], "csch": [(lambda x: True, "Csch")], "asinh": [(lambda x: True, "ArcSinh")], "acosh": [(lambda x: True, "ArcCosh")], "atanh": [(lambda x: True, "ArcTanh")], "acoth": [(lambda x: True, "ArcCoth")], "asech": [(lambda x: True, "ArcSech")], "acsch": [(lambda x: True, "ArcCsch")], "conjugate": [(lambda x: True, "Conjugate")], "Max": [(lambda x: True, "Max")], "Min": [(lambda x: True, "Min")], } class MCodePrinter(CodePrinter): """A printer to convert python expressions to strings of the Wolfram's Mathematica code """ printmethod = "_mcode" _default_settings = { 'order': None, 'full_prec': 'auto', 'precision': 15, 'user_functions': {}, 'human': True, 'allow_unknown_functions': False, } _number_symbols = set() _not_supported = set() def __init__(self, settings={}): """Register function mappings supplied by user""" CodePrinter.__init__(self, settings) self.known_functions = dict(known_functions) userfuncs = settings.get('user_functions', {}) for k, v in userfuncs.items(): if not isinstance(v, list): userfuncs[k] = [(lambda x: True, v)] self.known_functions.update(userfuncs) doprint = StrPrinter.doprint def _print_Pow(self, expr): PREC = precedence(expr) return '%s^%s' % (self.parenthesize(expr.base, PREC), self.parenthesize(expr.exp, PREC)) def _print_Mul(self, expr): PREC = precedence(expr) c, nc = expr.args_cnc() res = super(MCodePrinter, self)._print_Mul(expr.func(c)) if nc: res += '' res += ''.join(self.parenthesize(a, PREC) for a in nc) return res def _print_Pi(self, expr): return 'Pi' def _print_Infinity(self, expr): return 'Infinity' def _print_NegativeInfinity(self, expr): return '-Infinity' def _print_list(self, expr): return '{' + ', '.join(self.doprint(a) for a in expr) + '}' _print_tuple = _print_list _print_Tuple = _print_list def _print_Matrix(self, expr): return self._print_list( [self._print_list(expr.row(i)) for i in range(expr.rows)] ) _print_ImmutableMatrix = _print_Matrix _print_ImmutableDenseMatrix = _print_Matrix _print_MutableDenseMatrix = _print_Matrix def _print_SparseMatrix(self, expr): from sympy.core.compatibility import default_sort_key def print_rule(pos, val): return '{} -> {}'.format( self.doprint((pos[0]+1, pos[1]+1)), self.doprint(val)) def print_data(): return self._print_list( [print_rule(key, value) for key, value in sorted(expr._smat.items(), key=default_sort_key)] ) def print_dims(): return self._print_list( [self.doprint(expr.rows), self.doprint(expr.cols)] ) return 'SparseArray[{}, {}]'.format(print_data(), print_dims()) _print_MutableSparseMatrix = _print_SparseMatrix _print_ImmutableSparseMatrix = _print_SparseMatrix def _print_Function(self, expr): if expr.func.__name__ in self.known_functions: cond_mfunc = self.known_functions[expr.func.__name__] for cond, mfunc in cond_mfunc: if cond(expr.args): return "%s[%s]" % (mfunc, self.stringify(expr.args, ", ")) return expr.func.__name__ + "[%s]" % self.stringify(expr.args, ", ") _print_MinMaxBase = _print_Function def _print_Integral(self, expr): if len(expr.variables) == 1 and not expr.limits[0][1:]: args = [expr.args[0], expr.variables[0]] else: args = expr.args return "Hold[Integrate[" + ', '.join(self.doprint(a) for a in args) + "]]" def _print_Sum(self, expr): return "Hold[Sum[" + ', '.join(self.doprint(a) for a in expr.args) + "]]" def _print_Derivative(self, expr): dexpr = expr.expr dvars = [i[0] if i[1] == 1 else i for i in expr.variable_count] return "Hold[D[" + ', '.join(self.doprint(a) for a in [dexpr] + dvars) + "]]" def mathematica_code(expr, *settings): r"""Converts an expr to a string of the Wolfram Mathematica code Examples ======== >>> from sympy import mathematica_code as mcode, symbols, sin >>> x = symbols('x') >>> mcode(sin(x).series(x).removeO()) '(1/120)x^5 - 1/6*x^3 + x' """ return MCodePrinter(settings).doprint(expr)
86574bafe10700eba05f08675f81fe77528e845b3a39151fcd512621d21c016a	from __future__ import print_function, division from functools import wraps from sympy.core import Add, Mul, Pow, S, sympify, Float from sympy.core.basic import Basic from sympy.core.containers import Tuple from sympy.core.compatibility import default_sort_key, string_types from sympy.core.function import Lambda from sympy.core.mul import _keep_coeff from sympy.core.symbol import Symbol from sympy.printing.str import StrPrinter from sympy.printing.precedence import precedence # Backwards compatibility from sympy.codegen.ast import Assignment class requires(object): """ Decorator for registering requirements on print methods. """ def __init__(self, *kwargs): self._req = kwargs def __call__(self, method): def _method_wrapper(self_, args, *kwargs): for k, v in self._req.items(): getattr(self_, k).update(v) return method(self_, args, *kwargs) return wraps(method)(_method_wrapper) class AssignmentError(Exception): """ Raised if an assignment variable for a loop is missing. """ pass class CodePrinter(StrPrinter): """ The base class for code-printing subclasses. """ _operators = { 'and': '&&', 'or': '\|\|', 'not': '!', } _default_settings = { 'order': None, 'full_prec': 'auto', 'error_on_reserved': False, 'reserved_word_suffix': '_', 'human': True, 'inline': False, 'allow_unknown_functions': False, } def __init__(self, settings=None): super(CodePrinter, self).__init__(settings=settings) if not hasattr(self, 'reserved_words'): self.reserved_words = set() def doprint(self, expr, assign_to=None): """ Print the expression as code. Parameters ---------- expr : Expression The expression to be printed. assign_to : Symbol, MatrixSymbol, or string (optional) If provided, the printed code will set the expression to a variable with name ``assign_to``. """ from sympy.matrices.expressions.matexpr import MatrixSymbol if isinstance(assign_to, string_types): if expr.is_Matrix: assign_to = MatrixSymbol(assign_to, expr.shape) else: assign_to = Symbol(assign_to) elif not isinstance(assign_to, (Basic, type(None))): raise TypeError("{0} cannot assign to object of type {1}".format( type(self).__name__, type(assign_to))) if assign_to: expr = Assignment(assign_to, expr) else: # _sympify is not enough b/c it errors on iterables expr = sympify(expr) # keep a set of expressions that are not strictly translatable to Code # and number constants that must be declared and initialized self._not_supported = set() self._number_symbols = set() lines = self._print(expr).splitlines() # format the output if self._settings["human"]: frontlines = [] if len(self._not_supported) > 0: frontlines.append(self._get_comment( "Not supported in {0}:".format(self.language))) for expr in sorted(self._not_supported, key=str): frontlines.append(self._get_comment(type(expr).__name__)) for name, value in sorted(self._number_symbols, key=str): frontlines.append(self._declare_number_const(name, value)) lines = frontlines + lines lines = self._format_code(lines) result = "\n".join(lines) else: lines = self._format_code(lines) num_syms = set([(k, self._print(v)) for k, v in self._number_symbols]) result = (num_syms, self._not_supported, "\n".join(lines)) self._not_supported = set() self._number_symbols = set() return result def _doprint_loops(self, expr, assign_to=None): # Here we print an expression that contains Indexed objects, they # correspond to arrays in the generated code. The low-level implementation # involves looping over array elements and possibly storing results in temporary # variables or accumulate it in the assign_to object. if self._settings.get('contract', True): from sympy.tensor import get_contraction_structure # Setup loops over non-dummy indices -- all terms need these indices = self._get_expression_indices(expr, assign_to) # Setup loops over dummy indices -- each term needs separate treatment dummies = get_contraction_structure(expr) else: indices = [] dummies = {None: (expr,)} openloop, closeloop = self._get_loop_opening_ending(indices) # terms with no summations first if None in dummies: text = StrPrinter.doprint(self, Add(dummies[None])) else: # If all terms have summations we must initialize array to Zero text = StrPrinter.doprint(self, 0) # skip redundant assignments (where lhs == rhs) lhs_printed = self._print(assign_to) lines = [] if text != lhs_printed: lines.extend(openloop) if assign_to is not None: text = self._get_statement("%s = %s" % (lhs_printed, text)) lines.append(text) lines.extend(closeloop) # then terms with summations for d in dummies: if isinstance(d, tuple): indices = self._sort_optimized(d, expr) openloop_d, closeloop_d = self._get_loop_opening_ending( indices) for term in dummies[d]: if term in dummies and not ([list(f.keys()) for f in dummies[term]] == [[None] for f in dummies[term]]): # If one factor in the term has it's own internal # contractions, those must be computed first. # (temporary variables?) raise NotImplementedError( "FIXME: no support for contractions in factor yet") else: # We need the lhs expression as an accumulator for # the loops, i.e # # for (int d=0; d < dim; d++){ # lhs[] = lhs[] + term[][d] # } ^.................. the accumulator # # We check if the expression already contains the # lhs, and raise an exception if it does, as that # syntax is currently undefined. FIXME: What would be # a good interpretation? if assign_to is None: raise AssignmentError( "need assignment variable for loops") if term.has(assign_to): raise ValueError("FIXME: lhs present in rhs,\ this is undefined in CodePrinter") lines.extend(openloop) lines.extend(openloop_d) text = "%s = %s" % (lhs_printed, StrPrinter.doprint( self, assign_to + term)) lines.append(self._get_statement(text)) lines.extend(closeloop_d) lines.extend(closeloop) return "\n".join(lines) def _get_expression_indices(self, expr, assign_to): from sympy.tensor import get_indices rinds, junk = get_indices(expr) linds, junk = get_indices(assign_to) # support broadcast of scalar if linds and not rinds: rinds = linds if rinds != linds: raise ValueError("lhs indices must match non-dummy" " rhs indices in %s" % expr) return self._sort_optimized(rinds, assign_to) def _sort_optimized(self, indices, expr): from sympy.tensor.indexed import Indexed if not indices: return [] # determine optimized loop order by giving a score to each index # the index with the highest score are put in the innermost loop. score_table = {} for i in indices: score_table[i] = 0 arrays = expr.atoms(Indexed) for arr in arrays: for p, ind in enumerate(arr.indices): try: score_table[ind] += self._rate_index_position(p) except KeyError: pass return sorted(indices, key=lambda x: score_table[x]) def _rate_index_position(self, p): """function to calculate score based on position among indices This method is used to sort loops in an optimized order, see CodePrinter._sort_optimized() """ raise NotImplementedError("This function must be implemented by " "subclass of CodePrinter.") def _get_statement(self, codestring): """Formats a codestring with the proper line ending.""" raise NotImplementedError("This function must be implemented by " "subclass of CodePrinter.") def _get_comment(self, text): """Formats a text string as a comment.""" raise NotImplementedError("This function must be implemented by " "subclass of CodePrinter.") def _declare_number_const(self, name, value): """Declare a numeric constant at the top of a function""" raise NotImplementedError("This function must be implemented by " "subclass of CodePrinter.") def _format_code(self, lines): """Take in a list of lines of code, and format them accordingly. This may include indenting, wrapping long lines, etc...""" raise NotImplementedError("This function must be implemented by " "subclass of CodePrinter.") def _get_loop_opening_ending(self, indices): """Returns a tuple (open_lines, close_lines) containing lists of codelines""" raise NotImplementedError("This function must be implemented by " "subclass of CodePrinter.") def _print_Dummy(self, expr): if expr.name.startswith('Dummy_'): return '_' + expr.name else: return '%s_%d' % (expr.name, expr.dummy_index) def _print_CodeBlock(self, expr): return '\n'.join([self._print(i) for i in expr.args]) def _print_String(self, string): return str(string) def _print_QuotedString(self, arg): return '"%s"' % arg.text def _print_Comment(self, string): return self._get_comment(str(string)) def _print_Assignment(self, expr): from sympy.functions.elementary.piecewise import Piecewise from sympy.matrices.expressions.matexpr import MatrixSymbol from sympy.tensor.indexed import IndexedBase lhs = expr.lhs rhs = expr.rhs # We special case assignments that take multiple lines if isinstance(expr.rhs, Piecewise): # Here we modify Piecewise so each expression is now # an Assignment, and then continue on the print. expressions = [] conditions = [] for (e, c) in rhs.args: expressions.append(Assignment(lhs, e)) conditions.append(c) temp = Piecewise(zip(expressions, conditions)) return self._print(temp) elif isinstance(lhs, MatrixSymbol): # Here we form an Assignment for each element in the array, # printing each one. lines = [] for (i, j) in self._traverse_matrix_indices(lhs): temp = Assignment(lhs[i, j], rhs[i, j]) code0 = self._print(temp) lines.append(code0) return "\n".join(lines) elif self._settings.get("contract", False) and (lhs.has(IndexedBase) or rhs.has(IndexedBase)): # Here we check if there is looping to be done, and if so # print the required loops. return self._doprint_loops(rhs, lhs) else: lhs_code = self._print(lhs) rhs_code = self._print(rhs) return self._get_statement("%s = %s" % (lhs_code, rhs_code)) def _print_AugmentedAssignment(self, expr): lhs_code = self._print(expr.lhs) rhs_code = self._print(expr.rhs) return self._get_statement("{0} {1} {2}".format( map(lambda arg: self._print(arg), [lhs_code, expr.op, rhs_code]))) def _print_FunctionCall(self, expr): return '%s(%s)' % ( expr.name, ', '.join(map(lambda arg: self._print(arg), expr.function_args))) def _print_Variable(self, expr): return self._print(expr.symbol) def _print_Statement(self, expr): arg, = expr.args return self._get_statement(self._print(arg)) def _print_Symbol(self, expr): name = super(CodePrinter, self)._print_Symbol(expr) if name in self.reserved_words: if self._settings['error_on_reserved']: msg = ('This expression includes the symbol "{}" which is a ' 'reserved keyword in this language.') raise ValueError(msg.format(name)) return name + self._settings['reserved_word_suffix'] else: return name def _print_Function(self, expr): if expr.func.__name__ in self.known_functions: cond_func = self.known_functions[expr.func.__name__] func = None if isinstance(cond_func, str): func = cond_func else: for cond, func in cond_func: if cond(expr.args): break if func is not None: try: return func([self.parenthesize(item, 0) for item in expr.args]) except TypeError: return "%s(%s)" % (func, self.stringify(expr.args, ", ")) elif hasattr(expr, '_imp_') and isinstance(expr._imp_, Lambda): # inlined function return self._print(expr._imp_(expr.args)) elif expr.is_Function and self._settings.get('allow_unknown_functions', False): return '%s(%s)' % (self._print(expr.func), ', '.join(map(self._print, expr.args))) else: return self._print_not_supported(expr) _print_Expr = _print_Function def _print_NumberSymbol(self, expr): if self._settings.get("inline", False): return self._print(Float(expr.evalf(self._settings["precision"]))) else: # A Number symbol that is not implemented here or with _printmethod # is registered and evaluated self._number_symbols.add((expr, Float(expr.evalf(self._settings["precision"])))) return str(expr) def _print_Catalan(self, expr): return self._print_NumberSymbol(expr) def _print_EulerGamma(self, expr): return self._print_NumberSymbol(expr) def _print_GoldenRatio(self, expr): return self._print_NumberSymbol(expr) def _print_TribonacciConstant(self, expr): return self._print_NumberSymbol(expr) def _print_Exp1(self, expr): return self._print_NumberSymbol(expr) def _print_Pi(self, expr): return self._print_NumberSymbol(expr) def _print_And(self, expr): PREC = precedence(expr) return (" %s " % self._operators['and']).join(self.parenthesize(a, PREC) for a in sorted(expr.args, key=default_sort_key)) def _print_Or(self, expr): PREC = precedence(expr) return (" %s " % self._operators['or']).join(self.parenthesize(a, PREC) for a in sorted(expr.args, key=default_sort_key)) def _print_Xor(self, expr): if self._operators.get('xor') is None: return self._print_not_supported(expr) PREC = precedence(expr) return (" %s " % self._operators['xor']).join(self.parenthesize(a, PREC) for a in expr.args) def _print_Equivalent(self, expr): if self._operators.get('equivalent') is None: return self._print_not_supported(expr) PREC = precedence(expr) return (" %s " % self._operators['equivalent']).join(self.parenthesize(a, PREC) for a in expr.args) def _print_Not(self, expr): PREC = precedence(expr) return self._operators['not'] + self.parenthesize(expr.args[0], PREC) def _print_Mul(self, expr): prec = precedence(expr) c, e = expr.as_coeff_Mul() if c < 0: expr = _keep_coeff(-c, e) sign = "-" else: sign = "" a = [] # items in the numerator b = [] # items that are in the denominator (if any) pow_paren = [] # Will collect all pow with more than one base element and exp = -1 if self.order not in ('old', 'none'): args = expr.as_ordered_factors() else: # use make_args in case expr was something like -x -> x args = Mul.make_args(expr) # Gather args for numerator/denominator for item in args: if item.is_commutative and item.is_Pow and item.exp.is_Rational and item.exp.is_negative: if item.exp != -1: b.append(Pow(item.base, -item.exp, evaluate=False)) else: if len(item.args[0].args) != 1 and isinstance(item.base, Mul): # To avoid situations like #14160 pow_paren.append(item) b.append(Pow(item.base, -item.exp)) else: a.append(item) a = a or [S.One] a_str = [self.parenthesize(x, prec) for x in a] b_str = [self.parenthesize(x, prec) for x in b] # To parenthesize Pow with exp = -1 and having more than one Symbol for item in pow_paren: if item.base in b: b_str[b.index(item.base)] = "(%s)" % b_str[b.index(item.base)] if len(b) == 0: return sign + ''.join(a_str) elif len(b) == 1: return sign + ''.join(a_str) + "/" + b_str[0] else: return sign + ''.join(a_str) + "/(%s)" % ''.join(b_str) def _print_not_supported(self, expr): self._not_supported.add(expr) return self.emptyPrinter(expr) # The following can not be simply translated into C or Fortran _print_Basic = _print_not_supported _print_ComplexInfinity = _print_not_supported _print_Derivative = _print_not_supported _print_ExprCondPair = _print_not_supported _print_GeometryEntity = _print_not_supported _print_Infinity = _print_not_supported _print_Integral = _print_not_supported _print_Interval = _print_not_supported _print_AccumulationBounds = _print_not_supported _print_Limit = _print_not_supported _print_Matrix = _print_not_supported _print_ImmutableMatrix = _print_not_supported _print_ImmutableDenseMatrix = _print_not_supported _print_MutableDenseMatrix = _print_not_supported _print_MatrixBase = _print_not_supported _print_DeferredVector = _print_not_supported _print_NaN = _print_not_supported _print_NegativeInfinity = _print_not_supported _print_Normal = _print_not_supported _print_Order = _print_not_supported _print_PDF = _print_not_supported _print_RootOf = _print_not_supported _print_RootsOf = _print_not_supported _print_RootSum = _print_not_supported _print_Sample = _print_not_supported _print_SparseMatrix = _print_not_supported _print_MutableSparseMatrix = _print_not_supported _print_ImmutableSparseMatrix = _print_not_supported _print_Uniform = _print_not_supported _print_Unit = _print_not_supported _print_Wild = _print_not_supported _print_WildFunction = _print_not_supported
5608116685ab73d5e5ff5b2daf52dda3a88c0d16d875cbe7cf0bb56b23011979	"""Tools for manipulating of large commutative expressions. """ from __future__ import print_function, division from sympy.core.add import Add from sympy.core.compatibility import iterable, is_sequence, SYMPY_INTS, range from sympy.core.mul import Mul, _keep_coeff from sympy.core.power import Pow from sympy.core.basic import Basic, preorder_traversal from sympy.core.expr import Expr from sympy.core.sympify import sympify from sympy.core.numbers import Rational, Integer, Number, I from sympy.core.singleton import S from sympy.core.symbol import Dummy from sympy.core.coreerrors import NonCommutativeExpression from sympy.core.containers import Tuple, Dict from sympy.utilities import default_sort_key from sympy.utilities.iterables import (common_prefix, common_suffix, variations, ordered) from collections import defaultdict _eps = Dummy(positive=True) def _isnumber(i): return isinstance(i, (SYMPY_INTS, float)) or i.is_Number def _monotonic_sign(self): """Return the value closest to 0 that ``self`` may have if all symbols are signed and the result is uniformly the same sign for all values of symbols. If a symbol is only signed but not known to be an integer or the result is 0 then a symbol representative of the sign of self will be returned. Otherwise, None is returned if a) the sign could be positive or negative or b) self is not in one of the following forms: - L(x, y, ...) + A: a function linear in all symbols x, y, ... with an additive constant; if A is zero then the function can be a monomial whose sign is monotonic over the range of the variables, e.g. (x + 1)*3 if x is nonnegative. - A/L(x, y, ...) + B: the inverse of a function linear in all symbols x, y, ... that does not have a sign change from positive to negative for any set of values for the variables. - M(x, y, ...) + A: a monomial M whose factors are all signed and a constant, A. - A/M(x, y, ...) + B: the inverse of a monomial and constants A and B. - P(x): a univariate polynomial Examples ======== >>> from sympy.core.exprtools import _monotonic_sign as F >>> from sympy import Dummy, S >>> nn = Dummy(integer=True, nonnegative=True) >>> p = Dummy(integer=True, positive=True) >>> p2 = Dummy(integer=True, positive=True) >>> F(nn + 1) 1 >>> F(p - 1) _nneg >>> F(nnp + 1) 1 >>> F(p2p + 1) 2 >>> F(nn - 1) # could be negative, zero or positive """ if not self.is_real: return if (-self).is_Symbol: rv = _monotonic_sign(-self) return rv if rv is None else -rv if not self.is_Add and self.as_numer_denom()[1].is_number: s = self if s.is_prime: if s.is_odd: return S(3) else: return S(2) elif s.is_composite: if s.is_odd: return S(9) else: return S(4) elif s.is_positive: if s.is_even: if s.is_prime is False: return S(4) else: return S(2) elif s.is_integer: return S.One else: return _eps elif s.is_negative: if s.is_even: return S(-2) elif s.is_integer: return S.NegativeOne else: return -_eps if s.is_zero or s.is_nonpositive or s.is_nonnegative: return S.Zero return None # univariate polynomial free = self.free_symbols if len(free) == 1: if self.is_polynomial(): from sympy.polys.polytools import real_roots from sympy.polys.polyroots import roots from sympy.polys.polyerrors import PolynomialError x = free.pop() x0 = _monotonic_sign(x) if x0 == _eps or x0 == -_eps: x0 = S.Zero if x0 is not None: d = self.diff(x) if d.is_number: currentroots = [] else: try: currentroots = real_roots(d) except (PolynomialError, NotImplementedError): currentroots = [r for r in roots(d, x) if r.is_real] y = self.subs(x, x0) if x.is_nonnegative and all(r <= x0 for r in currentroots): if y.is_nonnegative and d.is_positive: if y: return y if y.is_positive else Dummy('pos', positive=True) else: return Dummy('nneg', nonnegative=True) if y.is_nonpositive and d.is_negative: if y: return y if y.is_negative else Dummy('neg', negative=True) else: return Dummy('npos', nonpositive=True) elif x.is_nonpositive and all(r >= x0 for r in currentroots): if y.is_nonnegative and d.is_negative: if y: return Dummy('pos', positive=True) else: return Dummy('nneg', nonnegative=True) if y.is_nonpositive and d.is_positive: if y: return Dummy('neg', negative=True) else: return Dummy('npos', nonpositive=True) else: n, d = self.as_numer_denom() den = None if n.is_number: den = _monotonic_sign(d) elif not d.is_number: if _monotonic_sign(n) is not None: den = _monotonic_sign(d) if den is not None and (den.is_positive or den.is_negative): v = nden if v.is_positive: return Dummy('pos', positive=True) elif v.is_nonnegative: return Dummy('nneg', nonnegative=True) elif v.is_negative: return Dummy('neg', negative=True) elif v.is_nonpositive: return Dummy('npos', nonpositive=True) return None # multivariate c, a = self.as_coeff_Add() v = None if not a.is_polynomial(): # F/A or A/F where A is a number and F is a signed, rational monomial n, d = a.as_numer_denom() if not (n.is_number or d.is_number): return if ( a.is_Mul or a.is_Pow) and \ a.is_rational and \ all(p.exp.is_Integer for p in a.atoms(Pow) if p.is_Pow) and \ (a.is_positive or a.is_negative): v = S(1) for ai in Mul.make_args(a): if ai.is_number: v = ai continue reps = {} for x in ai.free_symbols: reps[x] = _monotonic_sign(x) if reps[x] is None: return v = ai.subs(reps) elif c: # signed linear expression if not any(p for p in a.atoms(Pow) if not p.is_number) and (a.is_nonpositive or a.is_nonnegative): free = list(a.free_symbols) p = {} for i in free: v = _monotonic_sign(i) if v is None: return p[i] = v or (_eps if i.is_nonnegative else -_eps) v = a.xreplace(p) if v is not None: rv = v + c if v.is_nonnegative and rv.is_positive: return rv.subs(_eps, 0) if v.is_nonpositive and rv.is_negative: return rv.subs(_eps, 0) def decompose_power(expr): """ Decompose power into symbolic base and integer exponent. This is strictly only valid if the exponent from which the integer is extracted is itself an integer or the base is positive. These conditions are assumed and not checked here. Examples ======== >>> from sympy.core.exprtools import decompose_power >>> from sympy.abc import x, y >>> decompose_power(x) (x, 1) >>> decompose_power(x2) (x, 2) >>> decompose_power(x(2y)) (xy, 2) >>> decompose_power(x(2y/3)) (x*(y/3), 2) """ base, exp = expr.as_base_exp() if exp.is_Number: if exp.is_Rational: if not exp.is_Integer: base = Pow(base, Rational(1, exp.q)) exp = exp.p else: base, exp = expr, 1 else: exp, tail = exp.as_coeff_Mul(rational=True) if exp is S.NegativeOne: base, exp = Pow(base, tail), -1 elif exp is not S.One: tail = _keep_coeff(Rational(1, exp.q), tail) base, exp = Pow(base, tail), exp.p else: base, exp = expr, 1 return base, exp def decompose_power_rat(expr): """ Decompose power into symbolic base and rational exponent. """ base, exp = expr.as_base_exp() if exp.is_Number: if not exp.is_Rational: base, exp = expr, 1 else: exp, tail = exp.as_coeff_Mul(rational=True) if exp is S.NegativeOne: base, exp = Pow(base, tail), -1 elif exp is not S.One: tail = _keep_coeff(Rational(1, exp.q), tail) base, exp = Pow(base, tail), exp.p else: base, exp = expr, 1 return base, exp class Factors(object): """Efficient representation of ``f_1f_2...f_n``.""" __slots__ = ['factors', 'gens'] def __init__(self, factors=None): # Factors """Initialize Factors from dict or expr. Examples ======== >>> from sympy.core.exprtools import Factors >>> from sympy.abc import x >>> from sympy import I >>> e = 2x3 >>> Factors(e) Factors({2: 1, x: 3}) >>> Factors(e.as_powers_dict()) Factors({2: 1, x: 3}) >>> f = _ >>> f.factors # underlying dictionary {2: 1, x: 3} >>> f.gens # base of each factor frozenset({2, x}) >>> Factors(0) Factors({0: 1}) >>> Factors(I) Factors({I: 1}) Notes ===== Although a dictionary can be passed, only minimal checking is performed: powers of -1 and I are made canonical. """ if isinstance(factors, (SYMPY_INTS, float)): factors = S(factors) if isinstance(factors, Factors): factors = factors.factors.copy() elif factors is None or factors is S.One: factors = {} elif factors is S.Zero or factors == 0: factors = {S.Zero: S.One} elif isinstance(factors, Number): n = factors factors = {} if n < 0: factors[S.NegativeOne] = S.One n = -n if n is not S.One: if n.is_Float or n.is_Integer or n is S.Infinity: factors[n] = S.One elif n.is_Rational: # since we're processing Numbers, the denominator is # stored with a negative exponent; all other factors # are left . if n.p != 1: factors[Integer(n.p)] = S.One factors[Integer(n.q)] = S.NegativeOne else: raise ValueError('Expected Float\|Rational\|Integer, not %s' % n) elif isinstance(factors, Basic) and not factors.args: factors = {factors: S.One} elif isinstance(factors, Expr): c, nc = factors.args_cnc() i = c.count(I) for _ in range(i): c.remove(I) factors = dict(Mul._from_args(c).as_powers_dict()) if i: factors[I] = S.Onei if nc: factors[Mul(nc, evaluate=False)] = S.One else: factors = factors.copy() # /!\ should be dict-like # tidy up -/+1 and I exponents if Rational handle = [] for k in factors: if k is I or k in (-1, 1): handle.append(k) if handle: i1 = S.One for k in handle: if not _isnumber(factors[k]): continue i1 = k*factors.pop(k) if i1 is not S.One: for a in i1.args if i1.is_Mul else [i1]: # at worst, -1.0I(-1)e if a is S.NegativeOne: factors[a] = S.One elif a is I: factors[I] = S.One elif a.is_Pow: if S.NegativeOne not in factors: factors[S.NegativeOne] = S.Zero factors[S.NegativeOne] += a.exp elif a == 1: factors[a] = S.One elif a == -1: factors[-a] = S.One factors[S.NegativeOne] = S.One else: raise ValueError('unexpected factor in i1: %s' % a) self.factors = factors try: self.gens = frozenset(factors.keys()) except AttributeError: raise TypeError('expecting Expr or dictionary') def __hash__(self): # Factors keys = tuple(ordered(self.factors.keys())) values = [self.factors[k] for k in keys] return hash((keys, values)) def __repr__(self): # Factors return "Factors({%s})" % ', '.join( ['%s: %s' % (k, v) for k, v in ordered(self.factors.items())]) @property def is_zero(self): # Factors """ >>> from sympy.core.exprtools import Factors >>> Factors(0).is_zero True """ f = self.factors return len(f) == 1 and S.Zero in f @property def is_one(self): # Factors """ >>> from sympy.core.exprtools import Factors >>> Factors(1).is_one True """ return not self.factors def as_expr(self): # Factors """Return the underlying expression. Examples ======== >>> from sympy.core.exprtools import Factors >>> from sympy.abc import x, y >>> Factors((xy*2).as_powers_dict()).as_expr() xy*2 """ args = [] for factor, exp in self.factors.items(): if exp != 1: b, e = factor.as_base_exp() if isinstance(exp, int): e = _keep_coeff(Integer(exp), e) elif isinstance(exp, Rational): e = _keep_coeff(exp, e) else: e = exp args.append(b*e) else: args.append(factor) return Mul(args) def mul(self, other): # Factors """Return Factors of ``self * other``. Examples ======== >>> from sympy.core.exprtools import Factors >>> from sympy.abc import x, y, z >>> a = Factors((xy2).as_powers_dict()) >>> b = Factors((xy/z).as_powers_dict()) >>> a.mul(b) Factors({x: 2, y: 3, z: -1}) >>> ab Factors({x: 2, y: 3, z: -1}) """ if not isinstance(other, Factors): other = Factors(other) if any(f.is_zero for f in (self, other)): return Factors(S.Zero) factors = dict(self.factors) for factor, exp in other.factors.items(): if factor in factors: exp = factors[factor] + exp if not exp: del factors[factor] continue factors[factor] = exp return Factors(factors) def normal(self, other): """Return ``self`` and ``other`` with ``gcd`` removed from each. The only differences between this and method ``div`` is that this is 1) optimized for the case when there are few factors in common and 2) this does not raise an error if ``other`` is zero. See Also ======== div """ if not isinstance(other, Factors): other = Factors(other) if other.is_zero: return (Factors(), Factors(S.Zero)) if self.is_zero: return (Factors(S.Zero), Factors()) self_factors = dict(self.factors) other_factors = dict(other.factors) for factor, self_exp in self.factors.items(): try: other_exp = other.factors[factor] except KeyError: continue exp = self_exp - other_exp if not exp: del self_factors[factor] del other_factors[factor] elif _isnumber(exp): if exp > 0: self_factors[factor] = exp del other_factors[factor] else: del self_factors[factor] other_factors[factor] = -exp else: r = self_exp.extract_additively(other_exp) if r is not None: if r: self_factors[factor] = r del other_factors[factor] else: # should be handled already del self_factors[factor] del other_factors[factor] else: sc, sa = self_exp.as_coeff_Add() if sc: oc, oa = other_exp.as_coeff_Add() diff = sc - oc if diff > 0: self_factors[factor] -= oc other_exp = oa elif diff < 0: self_factors[factor] -= sc other_factors[factor] -= sc other_exp = oa - diff else: self_factors[factor] = sa other_exp = oa if other_exp: other_factors[factor] = other_exp else: del other_factors[factor] return Factors(self_factors), Factors(other_factors) def div(self, other): # Factors """Return ``self`` and ``other`` with ``gcd`` removed from each. This is optimized for the case when there are many factors in common. Examples ======== >>> from sympy.core.exprtools import Factors >>> from sympy.abc import x, y, z >>> from sympy import S >>> a = Factors((xy*2).as_powers_dict()) >>> a.div(a) (Factors({}), Factors({})) >>> a.div(xz) (Factors({y: 2}), Factors({z: 1})) The ``/`` operator only gives ``quo``: >>> a/x Factors({y: 2}) Factors treats its factors as though they are all in the numerator, so if you violate this assumption the results will be correct but will not strictly correspond to the numerator and denominator of the ratio: >>> a.div(x/z) (Factors({y: 2}), Factors({z: -1})) Factors is also naive about bases: it does not attempt any denesting of Rational-base terms, for example the following does not become 2*(2x)/2. >>> Factors(2*(2x + 2)).div(S(8)) (Factors({2: 2x + 2}), Factors({8: 1})) factor_terms can clean up such Rational-bases powers: >>> from sympy.core.exprtools import factor_terms >>> n, d = Factors(2(2x + 2)).div(S(8)) >>> n.as_expr()/d.as_expr() 2*(2x + 2)/8 >>> factor_terms(_) 2*(2x)/2 """ quo, rem = dict(self.factors), {} if not isinstance(other, Factors): other = Factors(other) if other.is_zero: raise ZeroDivisionError if self.is_zero: return (Factors(S.Zero), Factors()) for factor, exp in other.factors.items(): if factor in quo: d = quo[factor] - exp if _isnumber(d): if d <= 0: del quo[factor] if d >= 0: if d: quo[factor] = d continue exp = -d else: r = quo[factor].extract_additively(exp) if r is not None: if r: quo[factor] = r else: # should be handled already del quo[factor] else: other_exp = exp sc, sa = quo[factor].as_coeff_Add() if sc: oc, oa = other_exp.as_coeff_Add() diff = sc - oc if diff > 0: quo[factor] -= oc other_exp = oa elif diff < 0: quo[factor] -= sc other_exp = oa - diff else: quo[factor] = sa other_exp = oa if other_exp: rem[factor] = other_exp else: assert factor not in rem continue rem[factor] = exp return Factors(quo), Factors(rem) def quo(self, other): # Factors """Return numerator Factor of ``self / other``. Examples ======== >>> from sympy.core.exprtools import Factors >>> from sympy.abc import x, y, z >>> a = Factors((xy2).as_powers_dict()) >>> b = Factors((xy/z).as_powers_dict()) >>> a.quo(b) # same as a/b Factors({y: 1}) """ return self.div(other)[0] def rem(self, other): # Factors """Return denominator Factors of ``self / other``. Examples ======== >>> from sympy.core.exprtools import Factors >>> from sympy.abc import x, y, z >>> a = Factors((xy2).as_powers_dict()) >>> b = Factors((xy/z).as_powers_dict()) >>> a.rem(b) Factors({z: -1}) >>> a.rem(a) Factors({}) """ return self.div(other)[1] def pow(self, other): # Factors """Return self raised to a non-negative integer power. Examples ======== >>> from sympy.core.exprtools import Factors >>> from sympy.abc import x, y >>> a = Factors((xy2).as_powers_dict()) >>> a2 Factors({x: 2, y: 4}) """ if isinstance(other, Factors): other = other.as_expr() if other.is_Integer: other = int(other) if isinstance(other, SYMPY_INTS) and other >= 0: factors = {} if other: for factor, exp in self.factors.items(): factors[factor] = expother return Factors(factors) else: raise ValueError("expected non-negative integer, got %s" % other) def gcd(self, other): # Factors """Return Factors of ``gcd(self, other)``. The keys are the intersection of factors with the minimum exponent for each factor. Examples ======== >>> from sympy.core.exprtools import Factors >>> from sympy.abc import x, y, z >>> a = Factors((xy2).as_powers_dict()) >>> b = Factors((xy/z).as_powers_dict()) >>> a.gcd(b) Factors({x: 1, y: 1}) """ if not isinstance(other, Factors): other = Factors(other) if other.is_zero: return Factors(self.factors) factors = {} for factor, exp in self.factors.items(): factor, exp = sympify(factor), sympify(exp) if factor in other.factors: lt = (exp - other.factors[factor]).is_negative if lt == True: factors[factor] = exp elif lt == False: factors[factor] = other.factors[factor] return Factors(factors) def lcm(self, other): # Factors """Return Factors of ``lcm(self, other)`` which are the union of factors with the maximum exponent for each factor. Examples ======== >>> from sympy.core.exprtools import Factors >>> from sympy.abc import x, y, z >>> a = Factors((xy2).as_powers_dict()) >>> b = Factors((xy/z).as_powers_dict()) >>> a.lcm(b) Factors({x: 1, y: 2, z: -1}) """ if not isinstance(other, Factors): other = Factors(other) if any(f.is_zero for f in (self, other)): return Factors(S.Zero) factors = dict(self.factors) for factor, exp in other.factors.items(): if factor in factors: exp = max(exp, factors[factor]) factors[factor] = exp return Factors(factors) def __mul__(self, other): # Factors return self.mul(other) def __divmod__(self, other): # Factors return self.div(other) def __div__(self, other): # Factors return self.quo(other) __truediv__ = __div__ def __mod__(self, other): # Factors return self.rem(other) def __pow__(self, other): # Factors return self.pow(other) def __eq__(self, other): # Factors if not isinstance(other, Factors): other = Factors(other) return self.factors == other.factors def __ne__(self, other): # Factors return not self == other class Term(object): """Efficient representation of ``coeff(numer/denom)``. """ __slots__ = ['coeff', 'numer', 'denom'] def __init__(self, term, numer=None, denom=None): # Term if numer is None and denom is None: if not term.is_commutative: raise NonCommutativeExpression( 'commutative expression expected') coeff, factors = term.as_coeff_mul() numer, denom = defaultdict(int), defaultdict(int) for factor in factors: base, exp = decompose_power(factor) if base.is_Add: cont, base = base.primitive() coeff = cont*exp if exp > 0: numer[base] += exp else: denom[base] += -exp numer = Factors(numer) denom = Factors(denom) else: coeff = term if numer is None: numer = Factors() if denom is None: denom = Factors() self.coeff = coeff self.numer = numer self.denom = denom def __hash__(self): # Term return hash((self.coeff, self.numer, self.denom)) def __repr__(self): # Term return "Term(%s, %s, %s)" % (self.coeff, self.numer, self.denom) def as_expr(self): # Term return self.coeff(self.numer.as_expr()/self.denom.as_expr()) def mul(self, other): # Term coeff = self.coeffother.coeff numer = self.numer.mul(other.numer) denom = self.denom.mul(other.denom) numer, denom = numer.normal(denom) return Term(coeff, numer, denom) def inv(self): # Term return Term(1/self.coeff, self.denom, self.numer) def quo(self, other): # Term return self.mul(other.inv()) def pow(self, other): # Term if other < 0: return self.inv().pow(-other) else: return Term(self.coeff * other, self.numer.pow(other), self.denom.pow(other)) def gcd(self, other): # Term return Term(self.coeff.gcd(other.coeff), self.numer.gcd(other.numer), self.denom.gcd(other.denom)) def lcm(self, other): # Term return Term(self.coeff.lcm(other.coeff), self.numer.lcm(other.numer), self.denom.lcm(other.denom)) def __mul__(self, other): # Term if isinstance(other, Term): return self.mul(other) else: return NotImplemented def __div__(self, other): # Term if isinstance(other, Term): return self.quo(other) else: return NotImplemented __truediv__ = __div__ def __pow__(self, other): # Term if isinstance(other, SYMPY_INTS): return self.pow(other) else: return NotImplemented def __eq__(self, other): # Term return (self.coeff == other.coeff and self.numer == other.numer and self.denom == other.denom) def __ne__(self, other): # Term return not self == other def _gcd_terms(terms, isprimitive=False, fraction=True): """Helper function for :func:`gcd_terms`. If ``isprimitive`` is True then the call to primitive for an Add will be skipped. This is useful when the content has already been extrated. If ``fraction`` is True then the expression will appear over a common denominator, the lcm of all term denominators. """ if isinstance(terms, Basic) and not isinstance(terms, Tuple): terms = Add.make_args(terms) terms = list(map(Term, [t for t in terms if t])) # there is some simplification that may happen if we leave this # here rather than duplicate it before the mapping of Term onto # the terms if len(terms) == 0: return S.Zero, S.Zero, S.One if len(terms) == 1: cont = terms[0].coeff numer = terms[0].numer.as_expr() denom = terms[0].denom.as_expr() else: cont = terms[0] for term in terms[1:]: cont = cont.gcd(term) for i, term in enumerate(terms): terms[i] = term.quo(cont) if fraction: denom = terms[0].denom for term in terms[1:]: denom = denom.lcm(term.denom) numers = [] for term in terms: numer = term.numer.mul(denom.quo(term.denom)) numers.append(term.coeffnumer.as_expr()) else: numers = [t.as_expr() for t in terms] denom = Term(S(1)).numer cont = cont.as_expr() numer = Add(numers) denom = denom.as_expr() if not isprimitive and numer.is_Add: _cont, numer = numer.primitive() cont = _cont return cont, numer, denom def gcd_terms(terms, isprimitive=False, clear=True, fraction=True): """Compute the GCD of ``terms`` and put them together. ``terms`` can be an expression or a non-Basic sequence of expressions which will be handled as though they are terms from a sum. If ``isprimitive`` is True the _gcd_terms will not run the primitive method on the terms. ``clear`` controls the removal of integers from the denominator of an Add expression. When True (default), all numerical denominator will be cleared; when False the denominators will be cleared only if all terms had numerical denominators other than 1. ``fraction``, when True (default), will put the expression over a common denominator. Examples ======== >>> from sympy.core import gcd_terms >>> from sympy.abc import x, y >>> gcd_terms((x + 1)2y + (x + 1)y2) y(x + 1)(x + y + 1) >>> gcd_terms(x/2 + 1) (x + 2)/2 >>> gcd_terms(x/2 + 1, clear=False) x/2 + 1 >>> gcd_terms(x/2 + y/2, clear=False) (x + y)/2 >>> gcd_terms(x/2 + 1/x) (x2 + 2)/(2x) >>> gcd_terms(x/2 + 1/x, fraction=False) (x + 2/x)/2 >>> gcd_terms(x/2 + 1/x, fraction=False, clear=False) x/2 + 1/x >>> gcd_terms(x/2/y + 1/x/y) (x*2 + 2)/(2xy) >>> gcd_terms(x/2/y + 1/x/y, clear=False) (x2/2 + 1)/(xy) >>> gcd_terms(x/2/y + 1/x/y, clear=False, fraction=False) (x/2 + 1/x)/y The ``clear`` flag was ignored in this case because the returned expression was a rational expression, not a simple sum. See Also ======== factor_terms, sympy.polys.polytools.terms_gcd """ def mask(terms): """replace nc portions of each term with a unique Dummy symbols and return the replacements to restore them""" args = [(a, []) if a.is_commutative else a.args_cnc() for a in terms] reps = [] for i, (c, nc) in enumerate(args): if nc: nc = Mul._from_args(nc) d = Dummy() reps.append((d, nc)) c.append(d) args[i] = Mul._from_args(c) else: args[i] = c return args, dict(reps) isadd = isinstance(terms, Add) addlike = isadd or not isinstance(terms, Basic) and \ is_sequence(terms, include=set) and \ not isinstance(terms, Dict) if addlike: if isadd: # i.e. an Add terms = list(terms.args) else: terms = sympify(terms) terms, reps = mask(terms) cont, numer, denom = _gcd_terms(terms, isprimitive, fraction) numer = numer.xreplace(reps) coeff, factors = cont.as_coeff_Mul() if not clear: c, _coeff = coeff.as_coeff_Mul() if not c.is_Integer and not clear and numer.is_Add: n, d = c.as_numer_denom() _numer = numer/d if any(a.as_coeff_Mul()[0].is_Integer for a in _numer.args): numer = _numer coeff = n_coeff return _keep_coeff(coeff, factorsnumer/denom, clear=clear) if not isinstance(terms, Basic): return terms if terms.is_Atom: return terms if terms.is_Mul: c, args = terms.as_coeff_mul() return _keep_coeff(c, Mul([gcd_terms(i, isprimitive, clear, fraction) for i in args]), clear=clear) def handle(a): # don't treat internal args like terms of an Add if not isinstance(a, Expr): if isinstance(a, Basic): return a.func([handle(i) for i in a.args]) return type(a)([handle(i) for i in a]) return gcd_terms(a, isprimitive, clear, fraction) if isinstance(terms, Dict): return Dict([(k, handle(v)) for k, v in terms.args]) return terms.func([handle(i) for i in terms.args]) def factor_terms(expr, radical=False, clear=False, fraction=False, sign=True): """Remove common factors from terms in all arguments without changing the underlying structure of the expr. No expansion or simplification (and no processing of non-commutatives) is performed. If radical=True then a radical common to all terms will be factored out of any Add sub-expressions of the expr. If clear=False (default) then coefficients will not be separated from a single Add if they can be distributed to leave one or more terms with integer coefficients. If fraction=True (default is False) then a common denominator will be constructed for the expression. If sign=True (default) then even if the only factor in common is a -1, it will be factored out of the expression. Examples ======== >>> from sympy import factor_terms, Symbol >>> from sympy.abc import x, y >>> factor_terms(x + x(2 + 4y)*3) x(8(2y + 1)*3 + 1) >>> A = Symbol('A', commutative=False) >>> factor_terms(xA + xA + xyA) x(yA + 2A) When ``clear`` is False, a rational will only be factored out of an Add expression if all terms of the Add have coefficients that are fractions: >>> factor_terms(x/2 + 1, clear=False) x/2 + 1 >>> factor_terms(x/2 + 1, clear=True) (x + 2)/2 If a -1 is all that can be factored out, to not factor it out, the flag ``sign`` must be False: >>> factor_terms(-x - y) -(x + y) >>> factor_terms(-x - y, sign=False) -x - y >>> factor_terms(-2x - 2y, sign=False) -2(x + y) See Also ======== gcd_terms, sympy.polys.polytools.terms_gcd """ def do(expr): from sympy.concrete.summations import Sum from sympy.simplify.simplify import factor_sum is_iterable = iterable(expr) if not isinstance(expr, Basic) or expr.is_Atom: if is_iterable: return type(expr)([do(i) for i in expr]) return expr if expr.is_Pow or expr.is_Function or \ is_iterable or not hasattr(expr, 'args_cnc'): args = expr.args newargs = tuple([do(i) for i in args]) if newargs == args: return expr return expr.func(newargs) if isinstance(expr, Sum): return factor_sum(expr, radical=radical, clear=clear, fraction=fraction, sign=sign) cont, p = expr.as_content_primitive(radical=radical, clear=clear) if p.is_Add: list_args = [do(a) for a in Add.make_args(p)] # get a common negative (if there) which gcd_terms does not remove if all(a.as_coeff_Mul()[0].extract_multiplicatively(-1) is not None for a in list_args): cont = -cont list_args = [-a for a in list_args] # watch out for exp(-(x+2)) which gcd_terms will change to exp(-x-2) special = {} for i, a in enumerate(list_args): b, e = a.as_base_exp() if e.is_Mul and e != Mul(e.args): list_args[i] = Dummy() special[list_args[i]] = a # rebuild p not worrying about the order which gcd_terms will fix p = Add._from_args(list_args) p = gcd_terms(p, isprimitive=True, clear=clear, fraction=fraction).xreplace(special) elif p.args: p = p.func( [do(a) for a in p.args]) rv = _keep_coeff(cont, p, clear=clear, sign=sign) return rv expr = sympify(expr) return do(expr) def _mask_nc(eq, name=None): """ Return ``eq`` with non-commutative objects replaced with Dummy symbols. A dictionary that can be used to restore the original values is returned: if it is None, the expression is noncommutative and cannot be made commutative. The third value returned is a list of any non-commutative symbols that appear in the returned equation. ``name``, if given, is the name that will be used with numered Dummy variables that will replace the non-commutative objects and is mainly used for doctesting purposes. Notes ===== All non-commutative objects other than Symbols are replaced with a non-commutative Symbol. Identical objects will be identified by identical symbols. If there is only 1 non-commutative object in an expression it will be replaced with a commutative symbol. Otherwise, the non-commutative entities are retained and the calling routine should handle replacements in this case since some care must be taken to keep track of the ordering of symbols when they occur within Muls. Examples ======== >>> from sympy.physics.secondquant import Commutator, NO, F, Fd >>> from sympy import symbols, Mul >>> from sympy.core.exprtools import _mask_nc >>> from sympy.abc import x, y >>> A, B, C = symbols('A,B,C', commutative=False) One nc-symbol: >>> _mask_nc(A2 - x2, 'd') (_d02 - x2, {_d0: A}, []) Multiple nc-symbols: >>> _mask_nc(A2 - B2, 'd') (A2 - B2, {}, [A, B]) An nc-object with nc-symbols but no others outside of it: >>> _mask_nc(1 + xCommutator(A, B), 'd') (_d0x + 1, {_d0: Commutator(A, B)}, []) >>> _mask_nc(NO(Fd(x)F(y)), 'd') (_d0, {_d0: NO(CreateFermion(x)AnnihilateFermion(y))}, []) Multiple nc-objects: >>> eq = xCommutator(A, B) + xCommutator(A, C)Commutator(A, B) >>> _mask_nc(eq, 'd') (x_d0 + x_d1_d0, {_d0: Commutator(A, B), _d1: Commutator(A, C)}, [_d0, _d1]) Multiple nc-objects and nc-symbols: >>> eq = ACommutator(A, B) + BCommutator(A, C) >>> _mask_nc(eq, 'd') (A_d0 + B_d1, {_d0: Commutator(A, B), _d1: Commutator(A, C)}, [_d0, _d1, A, B]) If there is an object that: - doesn't contain nc-symbols - but has arguments which derive from Basic, not Expr - and doesn't define an _eval_is_commutative routine then it will give False (or None?) for the is_commutative test. Such objects are also removed by this routine: >>> from sympy import Basic >>> eq = (1 + Mul(Basic(), Basic(), evaluate=False)) >>> eq.is_commutative False >>> _mask_nc(eq, 'd') (_d0*2 + 1, {_d0: Basic()}, []) """ name = name or 'mask' # Make Dummy() append sequential numbers to the name def numbered_names(): i = 0 while True: yield name + str(i) i += 1 names = numbered_names() def Dummy(args, *kwargs): from sympy import Dummy return Dummy(next(names), args, kwargs) expr = eq if expr.is_commutative: return eq, {}, [] # identify nc-objects; symbols and other rep = [] nc_obj = set() nc_syms = set() pot = preorder_traversal(expr, keys=default_sort_key) for i, a in enumerate(pot): if any(a == r[0] for r in rep): pot.skip() elif not a.is_commutative: if a.is_symbol: nc_syms.add(a) pot.skip() elif not (a.is_Add or a.is_Mul or a.is_Pow): nc_obj.add(a) pot.skip() # If there is only one nc symbol or object, it can be factored regularly # but polys is going to complain, so replace it with a Dummy. if len(nc_obj) == 1 and not nc_syms: rep.append((nc_obj.pop(), Dummy())) elif len(nc_syms) == 1 and not nc_obj: rep.append((nc_syms.pop(), Dummy())) # Any remaining nc-objects will be replaced with an nc-Dummy and # identified as an nc-Symbol to watch out for nc_obj = sorted(nc_obj, key=default_sort_key) for n in nc_obj: nc = Dummy(commutative=False) rep.append((n, nc)) nc_syms.add(nc) expr = expr.subs(rep) nc_syms = list(nc_syms) nc_syms.sort(key=default_sort_key) return expr, {v: k for k, v in rep}, nc_syms def factor_nc(expr): """Return the factored form of ``expr`` while handling non-commutative expressions. Examples ======== >>> from sympy.core.exprtools import factor_nc >>> from sympy import Symbol >>> from sympy.abc import x >>> A = Symbol('A', commutative=False) >>> B = Symbol('B', commutative=False) >>> factor_nc((x2 + 2Ax + A2).expand()) (x + A)2 >>> factor_nc(((x + A)(x + B)).expand()) (x + A)(x + B) """ from sympy.simplify.simplify import powsimp from sympy.polys import gcd, factor def _pemexpand(expr): "Expand with the minimal set of hints necessary to check the result." return expr.expand(deep=True, mul=True, power_exp=True, power_base=False, basic=False, multinomial=True, log=False) expr = sympify(expr) if not isinstance(expr, Expr) or not expr.args: return expr if not expr.is_Add: return expr.func([factor_nc(a) for a in expr.args]) expr, rep, nc_symbols = _mask_nc(expr) if rep: return factor(expr).subs(rep) else: args = [a.args_cnc() for a in Add.make_args(expr)] c = g = l = r = S.One hit = False # find any commutative gcd term for i, a in enumerate(args): if i == 0: c = Mul._from_args(a[0]) elif a[0]: c = gcd(c, Mul._from_args(a[0])) else: c = S.One if c is not S.One: hit = True c, g = c.as_coeff_Mul() if g is not S.One: for i, (cc, _) in enumerate(args): cc = list(Mul.make_args(Mul._from_args(list(cc))/g)) args[i][0] = cc for i, (cc, _) in enumerate(args): cc[0] = cc[0]/c args[i][0] = cc # find any noncommutative common prefix for i, a in enumerate(args): if i == 0: n = a[1][:] else: n = common_prefix(n, a[1]) if not n: # is there a power that can be extracted? if not args[0][1]: break b, e = args[0][1][0].as_base_exp() ok = False if e.is_Integer: for t in args: if not t[1]: break bt, et = t[1][0].as_base_exp() if et.is_Integer and bt == b: e = min(e, et) else: break else: ok = hit = True l = be il = b-e for i, a in enumerate(args): args[i][1][0] = ilargs[i][1][0] break if not ok: break else: hit = True lenn = len(n) l = Mul(n) for i, a in enumerate(args): args[i][1] = args[i][1][lenn:] # find any noncommutative common suffix for i, a in enumerate(args): if i == 0: n = a[1][:] else: n = common_suffix(n, a[1]) if not n: # is there a power that can be extracted? if not args[0][1]: break b, e = args[0][1][-1].as_base_exp() ok = False if e.is_Integer: for t in args: if not t[1]: break bt, et = t[1][-1].as_base_exp() if et.is_Integer and bt == b: e = min(e, et) else: break else: ok = hit = True r = be il = b-e for i, a in enumerate(args): args[i][1][-1] = args[i][1][-1]il break if not ok: break else: hit = True lenn = len(n) r = Mul(n) for i, a in enumerate(args): args[i][1] = a[1][:len(a[1]) - lenn] if hit: mid = Add([Mul(cc)Mul(nc) for cc, nc in args]) else: mid = expr # sort the symbols so the Dummys would appear in the same # order as the original symbols, otherwise you may introduce # a factor of -1, e.g. A2 - B2) -- {A:y, B:x} --> y2 - x2 # and the former factors into two terms, (A - B)(A + B) while the # latter factors into 3 terms, (-1)(x - y)(x + y) rep1 = [(n, Dummy()) for n in sorted(nc_symbols, key=default_sort_key)] unrep1 = [(v, k) for k, v in rep1] unrep1.reverse() new_mid, r2, _ = _mask_nc(mid.subs(rep1)) new_mid = powsimp(factor(new_mid)) new_mid = new_mid.subs(r2).subs(unrep1) if new_mid.is_Pow: return _keep_coeff(c, glnew_midr) if new_mid.is_Mul: # XXX TODO there should be a way to inspect what order the terms # must be in and just select the plausible ordering without # checking permutations cfac = [] ncfac = [] for f in new_mid.args: if f.is_commutative: cfac.append(f) else: b, e = f.as_base_exp() if e.is_Integer: ncfac.extend([b]e) else: ncfac.append(f) pre_mid = gMul(cfac)l target = _pemexpand(expr/c) for s in variations(ncfac, len(ncfac)): ok = pre_midMul(s)r if _pemexpand(ok) == target: return _keep_coeff(c, ok) # mid was an Add that didn't factor successfully return _keep_coeff(c, glmid*r)
9b13f65ecfbdb6b3d6100fcc4bb6342f096d63db8010222ada8bb4cbb14cfcd9	""" There are three types of functions implemented in SymPy: 1) defined functions (in the sense that they can be evaluated) like exp or sin; they have a name and a body: f = exp 2) undefined function which have a name but no body. Undefined functions can be defined using a Function class as follows: f = Function('f') (the result will be a Function instance) 3) anonymous function (or lambda function) which have a body (defined with dummy variables) but have no name: f = Lambda(x, exp(x)x) f = Lambda((x, y), exp(x)y) The fourth type of functions are composites, like (sin + cos)(x); these work in SymPy core, but are not yet part of SymPy. Examples ======== >>> import sympy >>> f = sympy.Function("f") >>> from sympy.abc import x >>> f(x) f(x) >>> print(sympy.srepr(f(x).func)) Function('f') >>> f(x).args (x,) """ from __future__ import print_function, division from .add import Add from .assumptions import ManagedProperties, _assume_defined from .basic import Basic, _atomic from .cache import cacheit from .compatibility import iterable, is_sequence, as_int, ordered, Iterable from .decorators import _sympifyit from .expr import Expr, AtomicExpr from .numbers import Rational, Float from .operations import LatticeOp from .rules import Transform from .singleton import S from .sympify import sympify from sympy.core.containers import Tuple, Dict from sympy.core.logic import fuzzy_and from sympy.core.compatibility import string_types, with_metaclass, range from sympy.utilities import default_sort_key from sympy.utilities.misc import filldedent from sympy.utilities.iterables import has_dups from sympy.core.evaluate import global_evaluate import sys import mpmath import mpmath.libmp as mlib import inspect from collections import Counter def _coeff_isneg(a): """Return True if the leading Number is negative. Examples ======== >>> from sympy.core.function import _coeff_isneg >>> from sympy import S, Symbol, oo, pi >>> _coeff_isneg(-3pi) True >>> _coeff_isneg(S(3)) False >>> _coeff_isneg(-oo) True >>> _coeff_isneg(Symbol('n', negative=True)) # coeff is 1 False For matrix expressions: >>> from sympy import MatrixSymbol, sqrt >>> A = MatrixSymbol("A", 3, 3) >>> _coeff_isneg(-sqrt(2)A) True >>> _coeff_isneg(sqrt(2)A) False """ if a.is_MatMul: a = a.args[0] if a.is_Mul: a = a.args[0] return a.is_Number and a.is_negative class PoleError(Exception): pass class ArgumentIndexError(ValueError): def __str__(self): return ("Invalid operation with argument number %s for Function %s" % (self.args[1], self.args[0])) def _getnargs(cls): if hasattr(cls, 'eval'): if sys.version_info < (3, ): return _getnargs_old(cls.eval) else: return _getnargs_new(cls.eval) else: return None def _getnargs_old(eval_): evalargspec = inspect.getargspec(eval_) if evalargspec.varargs: return None else: evalargs = len(evalargspec.args) - 1 # subtract 1 for cls if evalargspec.defaults: # if there are default args then they are optional; the # fewest args will occur when all defaults are used and # the most when none are used (i.e. all args are given) return tuple(range( evalargs - len(evalargspec.defaults), evalargs + 1)) return evalargs def _getnargs_new(eval_): parameters = inspect.signature(eval_).parameters.items() if [p for n,p in parameters if p.kind == p.VAR_POSITIONAL]: return None else: p_or_k = [p for n,p in parameters if p.kind == p.POSITIONAL_OR_KEYWORD] num_no_default = len(list(filter(lambda p:p.default == p.empty, p_or_k))) num_with_default = len(list(filter(lambda p:p.default != p.empty, p_or_k))) if not num_with_default: return num_no_default return tuple(range(num_no_default, num_no_default+num_with_default+1)) class FunctionClass(ManagedProperties): """ Base class for function classes. FunctionClass is a subclass of type. Use Function('<function name>' [ , signature ]) to create undefined function classes. """ _new = type.__new__ def __init__(cls, args, *kwargs): # honor kwarg value or class-defined value before using # the number of arguments in the eval function (if present) nargs = kwargs.pop('nargs', cls.__dict__.get('nargs', _getnargs(cls))) # Canonicalize nargs here; change to set in nargs. if is_sequence(nargs): if not nargs: raise ValueError(filldedent(''' Incorrectly specified nargs as %s: if there are no arguments, it should be `nargs = 0`; if there are any number of arguments, it should be `nargs = None`''' % str(nargs))) nargs = tuple(ordered(set(nargs))) elif nargs is not None: nargs = (as_int(nargs),) cls._nargs = nargs super(FunctionClass, cls).__init__(args, kwargs) @property def __signature__(self): """ Allow Python 3's inspect.signature to give a useful signature for Function subclasses. """ # Python 3 only, but backports (like the one in IPython) still might # call this. try: from inspect import signature except ImportError: return None # TODO: Look at nargs return signature(self.eval) @property def free_symbols(self): return set() @property def xreplace(self): # Function needs args so we define a property that returns # a function that takes args...and then use that function # to return the right value return lambda rule, _: rule.get(self, self) @property def nargs(self): """Return a set of the allowed number of arguments for the function. Examples ======== >>> from sympy.core.function import Function >>> from sympy.abc import x, y >>> f = Function('f') If the function can take any number of arguments, the set of whole numbers is returned: >>> Function('f').nargs Naturals0 If the function was initialized to accept one or more arguments, a corresponding set will be returned: >>> Function('f', nargs=1).nargs {1} >>> Function('f', nargs=(2, 1)).nargs {1, 2} The undefined function, after application, also has the nargs attribute; the actual number of arguments is always available by checking the ``args`` attribute: >>> f = Function('f') >>> f(1).nargs Naturals0 >>> len(f(1).args) 1 """ from sympy.sets.sets import FiniteSet # XXX it would be nice to handle this in __init__ but there are import # problems with trying to import FiniteSet there return FiniteSet(self._nargs) if self._nargs else S.Naturals0 def __repr__(cls): return cls.__name__ class Application(with_metaclass(FunctionClass, Basic)): """ Base class for applied functions. Instances of Application represent the result of applying an application of any type to any object. """ is_Function = True @cacheit def __new__(cls, args, *options): from sympy.sets.fancysets import Naturals0 from sympy.sets.sets import FiniteSet args = list(map(sympify, args)) evaluate = options.pop('evaluate', global_evaluate[0]) # WildFunction (and anything else like it) may have nargs defined # and we throw that value away here options.pop('nargs', None) if options: raise ValueError("Unknown options: %s" % options) if evaluate: evaluated = cls.eval(args) if evaluated is not None: return evaluated obj = super(Application, cls).__new__(cls, args, options) # make nargs uniform here try: # things passing through here: # - functions subclassed from Function (e.g. myfunc(1).nargs) # - functions like cos(1).nargs # - AppliedUndef with given nargs like Function('f', nargs=1)(1).nargs # Canonicalize nargs here if is_sequence(obj.nargs): nargs = tuple(ordered(set(obj.nargs))) elif obj.nargs is not None: nargs = (as_int(obj.nargs),) else: nargs = None except AttributeError: # things passing through here: # - WildFunction('f').nargs # - AppliedUndef with no nargs like Function('f')(1).nargs nargs = obj._nargs # note the underscore here # convert to FiniteSet obj.nargs = FiniteSet(nargs) if nargs else Naturals0() return obj @classmethod def eval(cls, args): """ Returns a canonical form of cls applied to arguments args. The eval() method is called when the class cls is about to be instantiated and it should return either some simplified instance (possible of some other class), or if the class cls should be unmodified, return None. Examples of eval() for the function "sign" --------------------------------------------- .. code-block:: python @classmethod def eval(cls, arg): if arg is S.NaN: return S.NaN if arg is S.Zero: return S.Zero if arg.is_positive: return S.One if arg.is_negative: return S.NegativeOne if isinstance(arg, Mul): coeff, terms = arg.as_coeff_Mul(rational=True) if coeff is not S.One: return cls(coeff) cls(terms) """ return @property def func(self): return self.__class__ def _eval_subs(self, old, new): if (old.is_Function and new.is_Function and callable(old) and callable(new) and old == self.func and len(self.args) in new.nargs): return new([i._subs(old, new) for i in self.args]) class Function(Application, Expr): """ Base class for applied mathematical functions. It also serves as a constructor for undefined function classes. Examples ======== First example shows how to use Function as a constructor for undefined function classes: >>> from sympy import Function, Symbol >>> x = Symbol('x') >>> f = Function('f') >>> g = Function('g')(x) >>> f f >>> f(x) f(x) >>> g g(x) >>> f(x).diff(x) Derivative(f(x), x) >>> g.diff(x) Derivative(g(x), x) Assumptions can be passed to Function. >>> f_real = Function('f', real=True) >>> f_real(x).is_real True Note that assumptions on a function are unrelated to the assumptions on the variable it is called on. If you want to add a relationship, subclass Function and define the appropriate ``_eval_is_assumption`` methods. In the following example Function is used as a base class for ``my_func`` that represents a mathematical function my_func. Suppose that it is well known, that my_func(0)* is 1 and my_func at infinity goes to 0, so we want those two simplifications to occur automatically. Suppose also that my_func(x) is real exactly when x is real. Here is an implementation that honours those requirements: >>> from sympy import Function, S, oo, I, sin >>> class my_func(Function): ... ... @classmethod ... def eval(cls, x): ... if x.is_Number: ... if x is S.Zero: ... return S.One ... elif x is S.Infinity: ... return S.Zero ... ... def _eval_is_real(self): ... return self.args[0].is_real ... >>> x = S('x') >>> my_func(0) + sin(0) 1 >>> my_func(oo) 0 >>> my_func(3.54).n() # Not yet implemented for my_func. my_func(3.54) >>> my_func(I).is_real False In order for ``my_func`` to become useful, several other methods would need to be implemented. See source code of some of the already implemented functions for more complete examples. Also, if the function can take more than one argument, then ``nargs`` must be defined, e.g. if ``my_func`` can take one or two arguments then, >>> class my_func(Function): ... nargs = (1, 2) ... >>> """ @property def _diff_wrt(self): return False @cacheit def __new__(cls, args, options): # Handle calls like Function('f') if cls is Function: return UndefinedFunction(args, *options) n = len(args) if n not in cls.nargs: # XXX: exception message must be in exactly this format to # make it work with NumPy's functions like vectorize(). See, # for example, https://github.com/numpy/numpy/issues/1697. # The ideal solution would be just to attach metadata to # the exception and change NumPy to take advantage of this. temp = ('%(name)s takes %(qual)s %(args)s ' 'argument%(plural)s (%(given)s given)') raise TypeError(temp % { 'name': cls, 'qual': 'exactly' if len(cls.nargs) == 1 else 'at least', 'args': min(cls.nargs), 'plural': 's'(min(cls.nargs) != 1), 'given': n}) evaluate = options.get('evaluate', global_evaluate[0]) result = super(Function, cls).__new__(cls, args, options) if evaluate and isinstance(result, cls) and result.args: pr2 = min(cls._should_evalf(a) for a in result.args) if pr2 > 0: pr = max(cls._should_evalf(a) for a in result.args) result = result.evalf(mlib.libmpf.prec_to_dps(pr)) return result @classmethod def _should_evalf(cls, arg): """ Decide if the function should automatically evalf(). By default (in this implementation), this happens if (and only if) the ARG is a floating point number. This function is used by __new__. Returns the precision to evalf to, or -1 if it shouldn't evalf. """ from sympy.core.evalf import pure_complex if arg.is_Float: return arg._prec if not arg.is_Add: return -1 m = pure_complex(arg) if m is None or not (m[0].is_Float or m[1].is_Float): return -1 l = [i._prec for i in m if i.is_Float] l.append(-1) return max(l) @classmethod def class_key(cls): from sympy.sets.fancysets import Naturals0 funcs = { 'exp': 10, 'log': 11, 'sin': 20, 'cos': 21, 'tan': 22, 'cot': 23, 'sinh': 30, 'cosh': 31, 'tanh': 32, 'coth': 33, 'conjugate': 40, 're': 41, 'im': 42, 'arg': 43, } name = cls.__name__ try: i = funcs[name] except KeyError: i = 0 if isinstance(cls.nargs, Naturals0) else 10000 return 4, i, name @property def is_commutative(self): """ Returns whether the function is commutative. """ if all(getattr(t, 'is_commutative') for t in self.args): return True else: return False def _eval_evalf(self, prec): # Lookup mpmath function based on name try: if isinstance(self, AppliedUndef): # Shouldn't lookup in mpmath but might have ._imp_ raise AttributeError fname = self.func.__name__ if not hasattr(mpmath, fname): from sympy.utilities.lambdify import MPMATH_TRANSLATIONS fname = MPMATH_TRANSLATIONS[fname] func = getattr(mpmath, fname) except (AttributeError, KeyError): try: return Float(self._imp_([i.evalf(prec) for i in self.args]), prec) except (AttributeError, TypeError, ValueError): return # Convert all args to mpf or mpc # Convert the arguments to higher precision than requested for the # final result. # XXX + 5 is a guess, it is similar to what is used in evalf.py. Should # we be more intelligent about it? try: args = [arg._to_mpmath(prec + 5) for arg in self.args] def bad(m): from mpmath import mpf, mpc # the precision of an mpf value is the last element # if that is 1 (and m[1] is not 1 which would indicate a # power of 2), then the eval failed; so check that none of # the arguments failed to compute to a finite precision. # Note: An mpc value has two parts, the re and imag tuple; # check each of those parts, too. Anything else is allowed to # pass if isinstance(m, mpf): m = m._mpf_ return m[1] !=1 and m[-1] == 1 elif isinstance(m, mpc): m, n = m._mpc_ return m[1] !=1 and m[-1] == 1 and \ n[1] !=1 and n[-1] == 1 else: return False if any(bad(a) for a in args): raise ValueError # one or more args failed to compute with significance except ValueError: return with mpmath.workprec(prec): v = func(args) return Expr._from_mpmath(v, prec) def _eval_derivative(self, s): # f(x).diff(s) -> x.diff(s) f.fdiff(1)(s) i = 0 l = [] for a in self.args: i += 1 da = a.diff(s) if da is S.Zero: continue try: df = self.fdiff(i) except ArgumentIndexError: df = Function.fdiff(self, i) l.append(df * da) return Add(l) def _eval_is_commutative(self): return fuzzy_and(a.is_commutative for a in self.args) def _eval_is_complex(self): return fuzzy_and(a.is_complex for a in self.args) def as_base_exp(self): """ Returns the method as the 2-tuple (base, exponent). """ return self, S.One def _eval_aseries(self, n, args0, x, logx): """ Compute an asymptotic expansion around args0, in terms of self.args. This function is only used internally by _eval_nseries and should not be called directly; derived classes can overwrite this to implement asymptotic expansions. """ from sympy.utilities.misc import filldedent raise PoleError(filldedent(''' Asymptotic expansion of %s around %s is not implemented.''' % (type(self), args0))) def _eval_nseries(self, x, n, logx): """ This function does compute series for multivariate functions, but the expansion is always in terms of one* variable. Examples ======== >>> from sympy import atan2 >>> from sympy.abc import x, y >>> atan2(x, y).series(x, n=2) atan2(0, y) + x/y + O(x2) >>> atan2(x, y).series(y, n=2) -y/x + atan2(x, 0) + O(y2) This function also computes asymptotic expansions, if necessary and possible: >>> from sympy import loggamma >>> loggamma(1/x)._eval_nseries(x,0,None) -1/x - log(x)/x + log(x)/2 + O(1) """ from sympy import Order from sympy.sets.sets import FiniteSet args = self.args args0 = [t.limit(x, 0) for t in args] if any(t.is_finite is False for t in args0): from sympy import oo, zoo, nan # XXX could use t.as_leading_term(x) here but it's a little # slower a = [t.compute_leading_term(x, logx=logx) for t in args] a0 = [t.limit(x, 0) for t in a] if any([t.has(oo, -oo, zoo, nan) for t in a0]): return self._eval_aseries(n, args0, x, logx) # Careful: the argument goes to oo, but only logarithmically so. We # are supposed to do a power series expansion "around the # logarithmic term". e.g. # f(1+x+log(x)) # -> f(1+logx) + xf'(1+logx) + O(x2) # where 'logx' is given in the argument a = [t._eval_nseries(x, n, logx) for t in args] z = [r - r0 for (r, r0) in zip(a, a0)] p = [Dummy() for t in z] q = [] v = None for ai, zi, pi in zip(a0, z, p): if zi.has(x): if v is not None: raise NotImplementedError q.append(ai + pi) v = pi else: q.append(ai) e1 = self.func(q) if v is None: return e1 s = e1._eval_nseries(v, n, logx) o = s.getO() s = s.removeO() s = s.subs(v, zi).expand() + Order(o.expr.subs(v, zi), x) return s if (self.func.nargs is S.Naturals0 or (self.func.nargs == FiniteSet(1) and args0[0]) or any(c > 1 for c in self.func.nargs)): e = self e1 = e.expand() if e == e1: #for example when e = sin(x+1) or e = sin(cos(x)) #let's try the general algorithm term = e.subs(x, S.Zero) if term.is_finite is False or term is S.NaN: raise PoleError("Cannot expand %s around 0" % (self)) series = term fact = S.One _x = Dummy('x') e = e.subs(x, _x) for i in range(n - 1): i += 1 fact = Rational(i) e = e.diff(_x) subs = e.subs(_x, S.Zero) if subs is S.NaN: # try to evaluate a limit if we have to subs = e.limit(_x, S.Zero) if subs.is_finite is False: raise PoleError("Cannot expand %s around 0" % (self)) term = subs(xi)/fact term = term.expand() series += term return series + Order(xn, x) return e1.nseries(x, n=n, logx=logx) arg = self.args[0] l = [] g = None # try to predict a number of terms needed nterms = n + 2 cf = Order(arg.as_leading_term(x), x).getn() if cf != 0: nterms = int(nterms / cf) for i in range(nterms): g = self.taylor_term(i, arg, g) g = g.nseries(x, n=n, logx=logx) l.append(g) return Add(l) + Order(xn, x) def fdiff(self, argindex=1): """ Returns the first derivative of the function. """ if not (1 <= argindex <= len(self.args)): raise ArgumentIndexError(self, argindex) ix = argindex - 1 A = self.args[ix] if A._diff_wrt: if len(self.args) == 1: return Derivative(self, A) if A.is_Symbol: for i, v in enumerate(self.args): if i != ix and A in v.free_symbols: # it can't be in any other argument's free symbols # issue 8510 break else: return Derivative(self, A) else: free = A.free_symbols for i, a in enumerate(self.args): if ix != i and a.free_symbols & free: break else: # there is no possible interaction bewtween args return Derivative(self, A) # See issue 4624 and issue 4719, 5600 and 8510 D = Dummy('xi_%i' % argindex, dummy_index=hash(A)) args = self.args[:ix] + (D,) + self.args[ix + 1:] return Subs(Derivative(self.func(args), D), D, A) def _eval_as_leading_term(self, x): """Stub that should be overridden by new Functions to return the first non-zero term in a series if ever an x-dependent argument whose leading term vanishes as x -> 0 might be encountered. See, for example, cos._eval_as_leading_term. """ from sympy import Order args = [a.as_leading_term(x) for a in self.args] o = Order(1, x) if any(x in a.free_symbols and o.contains(a) for a in args): # Whereas x and any finite number are contained in O(1, x), # expressions like 1/x are not. If any arg simplified to a # vanishing expression as x -> 0 (like x or x*2, but not # 3, 1/x, etc...) then the _eval_as_leading_term is needed # to supply the first non-zero term of the series, # # e.g. expression leading term # ---------- ------------ # cos(1/x) cos(1/x) # cos(cos(x)) cos(1) # cos(x) 1 <- _eval_as_leading_term needed # sin(x) x <- _eval_as_leading_term needed # raise NotImplementedError( '%s has no _eval_as_leading_term routine' % self.func) else: return self.func(args) def _sage_(self): import sage.all as sage fname = self.func.__name__ func = getattr(sage, fname,None) args = [arg._sage_() for arg in self.args] # In the case the function is not known in sage: if func is None: import sympy if getattr(sympy, fname,None) is None: # abstract function return sage.function(fname)(args) else: # the function defined in sympy is not known in sage # this exception is caught in sage raise AttributeError return func(args) class AppliedUndef(Function): """ Base class for expressions resulting from the application of an undefined function. """ is_number = False def __new__(cls, args, options): args = list(map(sympify, args)) obj = super(AppliedUndef, cls).__new__(cls, args, *options) return obj def _eval_as_leading_term(self, x): return self def _sage_(self): import sage.all as sage fname = str(self.func) args = [arg._sage_() for arg in self.args] func = sage.function(fname)(args) return func @property def _diff_wrt(self): """ Allow derivatives wrt to undefined functions. Examples ======== >>> from sympy import Function, Symbol >>> f = Function('f') >>> x = Symbol('x') >>> f(x)._diff_wrt True >>> f(x).diff(x) Derivative(f(x), x) """ return True class UndefinedFunction(FunctionClass): """ The (meta)class of undefined functions. """ def __new__(mcl, name, bases=(AppliedUndef,), __dict__=None, kwargs): __dict__ = __dict__ or {} # Allow Function('f', real=True) __dict__.update({'is_' + arg: val for arg, val in kwargs.items() if arg in _assume_defined}) # You can add other attributes, although they do have to be hashable # (but seriously, if you want to add anything other than assumptions, # just subclass Function) __dict__.update(kwargs) # Save these for __eq__ __dict__.update({'_extra_kwargs': kwargs}) __dict__['__module__'] = None # For pickling ret = super(UndefinedFunction, mcl).__new__(mcl, name, bases, __dict__) ret.name = name return ret def __instancecheck__(cls, instance): return cls in type(instance).__mro__ _extra_kwargs = {} def __hash__(self): return hash((self.class_key(), frozenset(self._extra_kwargs.items()))) def __eq__(self, other): return (isinstance(other, self.__class__) and self.class_key() == other.class_key() and self._extra_kwargs == other._extra_kwargs) def __ne__(self, other): return not self == other class WildFunction(Function, AtomicExpr): """ A WildFunction function matches any function (with its arguments). Examples ======== >>> from sympy import WildFunction, Function, cos >>> from sympy.abc import x, y >>> F = WildFunction('F') >>> f = Function('f') >>> F.nargs Naturals0 >>> x.match(F) >>> F.match(F) {F_: F_} >>> f(x).match(F) {F_: f(x)} >>> cos(x).match(F) {F_: cos(x)} >>> f(x, y).match(F) {F_: f(x, y)} To match functions with a given number of arguments, set ``nargs`` to the desired value at instantiation: >>> F = WildFunction('F', nargs=2) >>> F.nargs {2} >>> f(x).match(F) >>> f(x, y).match(F) {F_: f(x, y)} To match functions with a range of arguments, set ``nargs`` to a tuple containing the desired number of arguments, e.g. if ``nargs = (1, 2)`` then functions with 1 or 2 arguments will be matched. >>> F = WildFunction('F', nargs=(1, 2)) >>> F.nargs {1, 2} >>> f(x).match(F) {F_: f(x)} >>> f(x, y).match(F) {F_: f(x, y)} >>> f(x, y, 1).match(F) """ include = set() def __init__(cls, name, assumptions): from sympy.sets.sets import Set, FiniteSet cls.name = name nargs = assumptions.pop('nargs', S.Naturals0) if not isinstance(nargs, Set): # Canonicalize nargs here. See also FunctionClass. if is_sequence(nargs): nargs = tuple(ordered(set(nargs))) elif nargs is not None: nargs = (as_int(nargs),) nargs = FiniteSet(nargs) cls.nargs = nargs def matches(self, expr, repl_dict={}, old=False): if not isinstance(expr, (AppliedUndef, Function)): return None if len(expr.args) not in self.nargs: return None repl_dict = repl_dict.copy() repl_dict[self] = expr return repl_dict class Derivative(Expr): """ Carries out differentiation of the given expression with respect to symbols. Examples ======== >>> from sympy import Derivative, Function, symbols, Subs >>> from sympy.abc import x, y >>> f, g = symbols('f g', cls=Function) >>> Derivative(x2, x, evaluate=True) 2x Denesting of derivatives retains the ordering of variables: >>> Derivative(Derivative(f(x, y), y), x) Derivative(f(x, y), y, x) Contiguously identical symbols are merged into a tuple giving the symbol and the count: >>> Derivative(f(x), x, x, y, x) Derivative(f(x), (x, 2), y, x) If the derivative cannot be performed, and evaluate is True, the order of the variables of differentiation will be made canonical: >>> Derivative(f(x, y), y, x, evaluate=True) Derivative(f(x, y), x, y) Derivatives with respect to undefined functions can be calculated: >>> Derivative(f(x)*2, f(x), evaluate=True) 2f(x) Such derivatives will show up when the chain rule is used to evalulate a derivative: >>> f(g(x)).diff(x) Derivative(f(g(x)), g(x))Derivative(g(x), x) Substitution is used to represent derivatives of functions with arguments that are not symbols or functions: >>> f(2x + 3).diff(x) == 2Subs(f(y).diff(y), y, 2x + 3) True Notes ===== Simplification of high-order derivatives: Because there can be a significant amount of simplification that can be done when multiple differentiations are performed, results will be automatically simplified in a fairly conservative fashion unless the keyword ``simplify`` is set to False. >>> from sympy import cos, sin, sqrt, diff, Function, symbols >>> from sympy.abc import x, y, z >>> f, g = symbols('f,g', cls=Function) >>> e = sqrt((x + 1)*2 + x) >>> diff(e, (x, 5), simplify=False).count_ops() 136 >>> diff(e, (x, 5)).count_ops() 30 Ordering of variables: If evaluate is set to True and the expression cannot be evaluated, the list of differentiation symbols will be sorted, that is, the expression is assumed to have continuous derivatives up to the order asked. Derivative wrt non-Symbols: For the most part, one may not differentiate wrt non-symbols. For example, we do not allow differentiation wrt `xy` because there are multiple ways of structurally defining where xy appears in an expression: a very strict definition would make (xyz).diff(xy) == 0. Derivatives wrt defined functions (like cos(x)) are not allowed, either: >>> (xyz).diff(xy) Traceback (most recent call last): ... ValueError: Can't calculate derivative wrt xy. To make it easier to work with variational calculus, however, derivatives wrt AppliedUndef and Derivatives are allowed. For example, in the Euler-Lagrange method one may write F(t, u, v) where u = f(t) and v = f'(t). These variables can be written explicity as functions of time:: >>> from sympy.abc import t >>> F = Function('F') >>> U = f(t) >>> V = U.diff(t) The derivative wrt f(t) can be obtained directly: >>> direct = F(t, U, V).diff(U) When differentiation wrt a non-Symbol is attempted, the non-Symbol is temporarily converted to a Symbol while the differentiation is performed and the same answer is obtained: >>> indirect = F(t, U, V).subs(U, x).diff(x).subs(x, U) >>> assert direct == indirect The implication of this non-symbol replacement is that all functions are treated as independent of other functions and the symbols are independent of the functions that contain them:: >>> x.diff(f(x)) 0 >>> g(x).diff(f(x)) 0 It also means that derivatives are assumed to depend only on the variables of differentiation, not on anything contained within the expression being differentiated:: >>> F = f(x) >>> Fx = F.diff(x) >>> Fx.diff(F) # derivative depends on x, not F 0 >>> Fxx = Fx.diff(x) >>> Fxx.diff(Fx) # derivative depends on x, not Fx 0 The last example can be made explicit by showing the replacement of Fx in Fxx with y: >>> Fxx.subs(Fx, y) Derivative(y, x) Since that in itself will evaluate to zero, differentiating wrt Fx will also be zero: >>> _.doit() 0 Replacing undefined functions with concrete expressions One must be careful to replace undefined functions with expressions that contain variables consistent with the function definition and the variables of differentiation or else insconsistent result will be obtained. Consider the following example: >>> eq = f(x)g(y) >>> eq.subs(f(x), xy).diff(x, y).doit() yDerivative(g(y), y) + g(y) >>> eq.diff(x, y).subs(f(x), xy).doit() yDerivative(g(y), y) The results differ because `f(x)` was replaced with an expression that involved both variables of differentiation. In the abstract case, differentiation of `f(x)` by `y` is 0; in the concrete case, the presence of `y` made that derivative nonvanishing and produced the extra `g(y)` term. Defining differentiation for an object An object must define ._eval_derivative(symbol) method that returns the differentiation result. This function only needs to consider the non-trivial case where expr contains symbol and it should call the diff() method internally (not _eval_derivative); Derivative should be the only one to call _eval_derivative. Any class can allow derivatives to be taken with respect to itself (while indicating its scalar nature). See the docstring of Expr._diff_wrt. See Also ======== _sort_variable_count """ is_Derivative = True @property def _diff_wrt(self): """An expression may be differentiated wrt a Derivative if it is in elementary form. Examples ======== >>> from sympy import Function, Derivative, cos >>> from sympy.abc import x >>> f = Function('f') >>> Derivative(f(x), x)._diff_wrt True >>> Derivative(cos(x), x)._diff_wrt False >>> Derivative(x + 1, x)._diff_wrt False A Derivative might be an unevaluated form of what will not be a valid variable of differentiation if evaluated. For example, >>> Derivative(f(f(x)), x).doit() Derivative(f(x), x)Derivative(f(f(x)), f(x)) Such an expression will present the same ambiguities as arise when dealing with any other product, like `2x`, so `_diff_wrt` is False: >>> Derivative(f(f(x)), x)._diff_wrt False """ return self.expr._diff_wrt and isinstance(self.doit(), Derivative) def __new__(cls, expr, variables, *kwargs): from sympy.matrices.common import MatrixCommon from sympy import Integer from sympy.tensor.array import Array, NDimArray from sympy.utilities.misc import filldedent expr = sympify(expr) try: has_symbol_set = isinstance(expr.free_symbols, set) except AttributeError: has_symbol_set = False if not has_symbol_set: raise ValueError(filldedent(''' Since there are no variables in the expression %s, it cannot be differentiated.''' % expr)) # determine value for variables if it wasn't given if not variables: variables = expr.free_symbols if len(variables) != 1: if expr.is_number: return S.Zero if len(variables) == 0: raise ValueError(filldedent(''' Since there are no variables in the expression, the variable(s) of differentiation must be supplied to differentiate %s''' % expr)) else: raise ValueError(filldedent(''' Since there is more than one variable in the expression, the variable(s) of differentiation must be supplied to differentiate %s''' % expr)) # Standardize the variables by sympifying them: variables = list(sympify(variables)) # Split the list of variables into a list of the variables we are diff # wrt, where each element of the list has the form (s, count) where # s is the entity to diff wrt and count is the order of the # derivative. variable_count = [] array_likes = (tuple, list, Tuple) for i, v in enumerate(variables): if isinstance(v, Integer): if i == 0: raise ValueError("First variable cannot be a number: %i" % v) count = v prev, prevcount = variable_count[-1] if prevcount != 1: raise TypeError("tuple {0} followed by number {1}".format((prev, prevcount), v)) if count == 0: variable_count.pop() else: variable_count[-1] = Tuple(prev, count) else: if isinstance(v, array_likes): if len(v) == 0: # Ignore empty tuples: Derivative(expr, ... , (), ... ) continue if isinstance(v[0], array_likes): # Derive by array: Derivative(expr, ... , [[x, y, z]], ... ) if len(v) == 1: v = Array(v[0]) count = 1 else: v, count = v v = Array(v) else: v, count = v if count == 0: continue else: count = 1 variable_count.append(Tuple(v, count)) # light evaluation of contiguous, identical # items: (x, 1), (x, 1) -> (x, 2) merged = [] for t in variable_count: v, c = t if c.is_negative: raise ValueError( 'order of differentiation must be nonnegative') if merged and merged[-1][0] == v: c += merged[-1][1] if not c: merged.pop() else: merged[-1] = Tuple(v, c) else: merged.append(t) variable_count = merged # sanity check of variables of differentation; we waited # until the counts were computed since some variables may # have been removed because the count was 0 for v, c in variable_count: # v must have _diff_wrt True if not v._diff_wrt: __ = '' # filler to make error message neater raise ValueError(filldedent(''' Can't calculate derivative wrt %s.%s''' % (v, __))) # We make a special case for 0th derivative, because there is no # good way to unambiguously print this. if len(variable_count) == 0: return expr evaluate = kwargs.get('evaluate', False) if evaluate: if isinstance(expr, Derivative): expr = expr.canonical variable_count = [ (v.canonical if isinstance(v, Derivative) else v, c) for v, c in variable_count] # Look for a quick exit if there are symbols that don't appear in # expression at all. Note, this cannot check non-symbols like # Derivatives as those can be created by intermediate # derivatives. zero = False free = expr.free_symbols for v, c in variable_count: vfree = v.free_symbols if c.is_positive and vfree: if isinstance(v, AppliedUndef): # these match exactly since # x.diff(f(x)) == g(x).diff(f(x)) == 0 # and are not created by differentiation D = Dummy() if not expr.xreplace({v: D}).has(D): zero = True break elif isinstance(v, Symbol) and v not in free: zero = True break else: if not free & vfree: # e.g. v is IndexedBase or Matrix zero = True break if zero: if isinstance(expr, (MatrixCommon, NDimArray)): return expr.zeros(expr.shape) else: return S.Zero # make the order of symbols canonical #TODO: check if assumption of discontinuous derivatives exist variable_count = cls._sort_variable_count(variable_count) # denest if isinstance(expr, Derivative): variable_count = list(expr.variable_count) + variable_count expr = expr.expr return Derivative(expr, variable_count, kwargs) # we return here if evaluate is False or if there is no # _eval_derivative method if not evaluate or not hasattr(expr, '_eval_derivative'): # return an unevaluated Derivative if evaluate and variable_count == [(expr, 1)] and expr.is_scalar: # special hack providing evaluation for classes # that have defined is_scalar=True but have no # _eval_derivative defined return S.One return Expr.__new__(cls, expr, variable_count) # evaluate the derivative by calling _eval_derivative method # of expr for each variable # ------------------------------------------------------------- nderivs = 0 # how many derivatives were performed unhandled = [] for i, (v, count) in enumerate(variable_count): old_expr = expr old_v = None is_symbol = v.is_symbol or isinstance(v, (Iterable, Tuple, MatrixCommon, NDimArray)) if not is_symbol: old_v = v v = Dummy('xi') expr = expr.xreplace({old_v: v}) # Derivatives and UndefinedFunctions are independent # of all others clashing = not (isinstance(old_v, Derivative) or \ isinstance(old_v, AppliedUndef)) if not v in expr.free_symbols and not clashing: return expr.diff(v) # expr's version of 0 if not old_v.is_scalar and not hasattr( old_v, '_eval_derivative'): # special hack providing evaluation for classes # that have defined is_scalar=True but have no # _eval_derivative defined expr = old_v.diff(old_v) # Evaluate the derivative `n` times. If # `_eval_derivative_n_times` is not overridden by the current # object, the default in `Basic` will call a loop over # `_eval_derivative`: obj = expr._eval_derivative_n_times(v, count) if obj is not None and obj.is_zero: return obj nderivs += count if old_v is not None: if obj is not None: # remove the dummy that was used obj = obj.subs(v, old_v) # restore expr and v expr = old_expr v = old_v if obj is None: # we've already checked for quick-exit conditions # that give 0 so the remaining variables # are contained in the expression but the expression # did not compute a derivative so we stop taking # derivatives unhandled = variable_count[i:] break expr = obj # what we have so far can be made canonical expr = expr.replace( lambda x: isinstance(x, Derivative), lambda x: x.canonical) if unhandled: if isinstance(expr, Derivative): unhandled = list(expr.variable_count) + unhandled expr = expr.expr expr = Expr.__new__(cls, expr, unhandled) if (nderivs > 1) == True and kwargs.get('simplify', True): from sympy.core.exprtools import factor_terms from sympy.simplify.simplify import signsimp expr = factor_terms(signsimp(expr)) return expr @property def canonical(cls): return cls.func(cls.expr, Derivative._sort_variable_count(cls.variable_count)) @classmethod def _sort_variable_count(cls, vc): """ Sort (variable, count) pairs into canonical order while retaining order of variables that do not commute during differentiation: symbols and functions commute with each other * derivatives commute with each other * a derivative doesn't commute with anything it contains * any other object is not allowed to commute if it has free symbols in common with another object Examples ======== >>> from sympy import Derivative, Function, symbols, cos >>> vsort = Derivative._sort_variable_count >>> x, y, z = symbols('x y z') >>> f, g, h = symbols('f g h', cls=Function) Contiguous items are collapsed into one pair: >>> vsort([(x, 1), (x, 1)]) [(x, 2)] >>> vsort([(y, 1), (f(x), 1), (y, 1), (f(x), 1)]) [(y, 2), (f(x), 2)] Ordering is canonical. >>> def vsort0(v): ... # docstring helper to ... # change vi -> (vi, 0), sort, and return vi vals ... return [i[0] for i in vsort([(i, 0) for i in v])] >>> vsort0(y, x) [x, y] >>> vsort0(g(y), g(x), f(y)) [f(y), g(x), g(y)] Symbols are sorted as far to the left as possible but never move to the left of a derivative having the same symbol in its variables; the same applies to AppliedUndef which are always sorted after Symbols: >>> dfx = f(x).diff(x) >>> assert vsort0(dfx, y) == [y, dfx] >>> assert vsort0(dfx, x) == [dfx, x] """ from sympy.utilities.iterables import uniq, topological_sort if not vc: return [] vc = list(vc) if len(vc) == 1: return [Tuple(vc[0])] V = list(range(len(vc))) E = [] v = lambda i: vc[i][0] D = Dummy() def _block(d, v, wrt=False): # return True if v should not come before d else False if d == v: return wrt if d.is_Symbol: return False if isinstance(d, Derivative): # a derivative blocks if any of it's variables contain # v; the wrt flag will return True for an exact match # and will cause an AppliedUndef to block if v is in # the arguments if any(_block(k, v, wrt=True) for k in d._wrt_variables): return True return False if not wrt and isinstance(d, AppliedUndef): return False if v.is_Symbol: return v in d.free_symbols if isinstance(v, AppliedUndef): return _block(d.xreplace({v: D}), D) return d.free_symbols & v.free_symbols for i in range(len(vc)): for j in range(i): if _block(v(j), v(i)): E.append((j,i)) # this is the default ordering to use in case of ties O = dict(zip(ordered(uniq([i for i, c in vc])), range(len(vc)))) ix = topological_sort((V, E), key=lambda i: O[v(i)]) # merge counts of contiguously identical items merged = [] for v, c in [vc[i] for i in ix]: if merged and merged[-1][0] == v: merged[-1][1] += c else: merged.append([v, c]) return [Tuple(i) for i in merged] def _eval_is_commutative(self): return self.expr.is_commutative def _eval_derivative(self, v): # If v (the variable of differentiation) is not in # self.variables, we might be able to take the derivative. if v not in self._wrt_variables: dedv = self.expr.diff(v) if isinstance(dedv, Derivative): return dedv.func(dedv.expr, (self.variable_count + dedv.variable_count)) # dedv (d(self.expr)/dv) could have simplified things such that the # derivative wrt things in self.variables can now be done. Thus, # we set evaluate=True to see if there are any other derivatives # that can be done. The most common case is when dedv is a simple # number so that the derivative wrt anything else will vanish. return self.func(dedv, self.variables, evaluate=True) # In this case v was in self.variables so the derivative wrt v has # already been attempted and was not computed, either because it # couldn't be or evaluate=False originally. variable_count = list(self.variable_count) variable_count.append((v, 1)) return self.func(self.expr, variable_count, evaluate=False) def doit(self, hints): expr = self.expr if hints.get('deep', True): expr = expr.doit(hints) hints['evaluate'] = True return self.func(expr, self.variable_count, hints) @_sympifyit('z0', NotImplementedError) def doit_numerically(self, z0): """ Evaluate the derivative at z numerically. When we can represent derivatives at a point, this should be folded into the normal evalf. For now, we need a special method. """ import mpmath from sympy.core.expr import Expr if len(self.free_symbols) != 1 or len(self.variables) != 1: raise NotImplementedError('partials and higher order derivatives') z = list(self.free_symbols)[0] def eval(x): f0 = self.expr.subs(z, Expr._from_mpmath(x, prec=mpmath.mp.prec)) f0 = f0.evalf(mlib.libmpf.prec_to_dps(mpmath.mp.prec)) return f0._to_mpmath(mpmath.mp.prec) return Expr._from_mpmath(mpmath.diff(eval, z0._to_mpmath(mpmath.mp.prec)), mpmath.mp.prec) @property def expr(self): return self._args[0] @property def _wrt_variables(self): # return the variables of differentiation without # respect to the type of count (int or symbolic) return [i[0] for i in self.variable_count] @property def variables(self): # TODO: deprecate? YES, make this 'enumerated_variables' and # name _wrt_variables as variables # TODO: support for `d^n`? rv = [] for v, count in self.variable_count: if not count.is_Integer: raise TypeError(filldedent(''' Cannot give expansion for symbolic count. If you just want a list of all variables of differentiation, use _wrt_variables.''')) rv.extend([v]count) return tuple(rv) @property def variable_count(self): return self._args[1:] @property def derivative_count(self): return sum([count for var, count in self.variable_count], 0) @property def free_symbols(self): return self.expr.free_symbols def _eval_subs(self, old, new): # The substitution (old, new) cannot be done inside # Derivative(expr, vars) for a variety of reasons # as handled below. if old in self._wrt_variables: # quick exit case if not getattr(new, '_diff_wrt', False): # case (0): new is not a valid variable of # differentiation if isinstance(old, Symbol): # don't introduce a new symbol if the old will do return Subs(self, old, new) else: xi = Dummy('xi') return Subs(self.xreplace({old: xi}), xi, new) # If both are Derivatives with the same expr, check if old is # equivalent to self or if old is a subderivative of self. if old.is_Derivative and old.expr == self.expr: if self.canonical == old.canonical: return new # collections.Counter doesn't have __le__ def _subset(a, b): return all((a[i] <= b[i]) == True for i in a) old_vars = Counter(dict(reversed(old.variable_count))) self_vars = Counter(dict(reversed(self.variable_count))) if _subset(old_vars, self_vars): return Derivative(new, (self_vars - old_vars).items()).canonical args = list(self.args) newargs = list(x._subs(old, new) for x in args) if args[0] == old: # complete replacement of self.expr # we already checked that the new is valid so we know # it won't be a problem should it appear in variables return Derivative(newargs) if newargs[0] != args[0]: # case (1) can't change expr by introducing something that is in # the _wrt_variables if it was already in the expr # e.g. # for Derivative(f(x, g(y)), y), x cannot be replaced with # anything that has y in it; for f(g(x), g(y)).diff(g(y)) # g(x) cannot be replaced with anything that has g(y) syms = {vi: Dummy() for vi in self._wrt_variables if not vi.is_Symbol} wrt = set(syms.get(vi, vi) for vi in self._wrt_variables) forbidden = args[0].xreplace(syms).free_symbols & wrt nfree = new.xreplace(syms).free_symbols ofree = old.xreplace(syms).free_symbols if (nfree - ofree) & forbidden: return Subs(self, old, new) viter = ((i, j) for ((i,_), (j,_)) in zip(newargs[1:], args[1:])) if any(i != j for i, j in viter): # a wrt-variable change # case (2) can't change vars by introducing a variable # that is contained in expr, e.g. # for Derivative(f(z, g(h(x), y)), y), y cannot be changed to # x, h(x), or g(h(x), y) for a in _atomic(self.expr, recursive=True): for i in range(1, len(newargs)): vi, _ = newargs[i] if a == vi and vi != args[i][0]: return Subs(self, old, new) # more arg-wise checks vc = newargs[1:] oldv = self._wrt_variables newe = self.expr subs = [] for i, (vi, ci) in enumerate(vc): if not vi._diff_wrt: # case (3) invalid differentiation expression so # create a replacement dummy xi = Dummy('xi_%i' % i) # replace the old valid variable with the dummy # in the expression newe = newe.xreplace({oldv[i]: xi}) # and replace the bad variable with the dummy vc[i] = (xi, ci) # and record the dummy with the new (invalid) # differentiation expression subs.append((xi, vi)) if subs: # handle any residual substitution in the expression newe = newe._subs(old, new) # return the Subs-wrapped derivative return Subs(Derivative(newe, vc), zip(subs)) # everything was ok return Derivative(newargs) def _eval_lseries(self, x, logx): dx = self.variables for term in self.expr.lseries(x, logx=logx): yield self.func(term, dx) def _eval_nseries(self, x, n, logx): arg = self.expr.nseries(x, n=n, logx=logx) o = arg.getO() dx = self.variables rv = [self.func(a, dx) for a in Add.make_args(arg.removeO())] if o: rv.append(o/x) return Add(rv) def _eval_as_leading_term(self, x): series_gen = self.expr.lseries(x) d = S.Zero for leading_term in series_gen: d = diff(leading_term, self.variables) if d != 0: break return d def _sage_(self): import sage.all as sage args = [arg._sage_() for arg in self.args] return sage.derivative(args) def as_finite_difference(self, points=1, x0=None, wrt=None): """ Expresses a Derivative instance as a finite difference. Parameters ========== points : sequence or coefficient, optional If sequence: discrete values (length >= order+1) of the independent variable used for generating the finite difference weights. If it is a coefficient, it will be used as the step-size for generating an equidistant sequence of length order+1 centered around ``x0``. Default: 1 (step-size 1) x0 : number or Symbol, optional the value of the independent variable (``wrt``) at which the derivative is to be approximated. Default: same as ``wrt``. wrt : Symbol, optional "with respect to" the variable for which the (partial) derivative is to be approximated for. If not provided it is required that the derivative is ordinary. Default: ``None``. Examples ======== >>> from sympy import symbols, Function, exp, sqrt, Symbol >>> x, h = symbols('x h') >>> f = Function('f') >>> f(x).diff(x).as_finite_difference() -f(x - 1/2) + f(x + 1/2) The default step size and number of points are 1 and ``order + 1`` respectively. We can change the step size by passing a symbol as a parameter: >>> f(x).diff(x).as_finite_difference(h) -f(-h/2 + x)/h + f(h/2 + x)/h We can also specify the discretized values to be used in a sequence: >>> f(x).diff(x).as_finite_difference([x, x+h, x+2h]) -3f(x)/(2h) + 2f(h + x)/h - f(2h + x)/(2h) The algorithm is not restricted to use equidistant spacing, nor do we need to make the approximation around ``x0``, but we can get an expression estimating the derivative at an offset: >>> e, sq2 = exp(1), sqrt(2) >>> xl = [x-h, x+h, x+eh] >>> f(x).diff(x, 1).as_finite_difference(xl, x+hsq2) # doctest: +ELLIPSIS 2h((h + sqrt(2)h)/(2h) - (-sqrt(2)h + h)/(2h))f(Eh + x)/... Partial derivatives are also supported: >>> y = Symbol('y') >>> d2fdxdy=f(x,y).diff(x,y) >>> d2fdxdy.as_finite_difference(wrt=x) -Derivative(f(x - 1/2, y), y) + Derivative(f(x + 1/2, y), y) We can apply ``as_finite_difference`` to ``Derivative`` instances in compound expressions using ``replace``: >>> (1 + 42f(x).diff(x)).replace(lambda arg: arg.is_Derivative, ... lambda arg: arg.as_finite_difference()) 42(-f(x - 1/2) + f(x + 1/2)) + 1 See also ======== sympy.calculus.finite_diff.apply_finite_diff sympy.calculus.finite_diff.differentiate_finite sympy.calculus.finite_diff.finite_diff_weights """ from ..calculus.finite_diff import _as_finite_diff return _as_finite_diff(self, points, x0, wrt) class Lambda(Expr): """ Lambda(x, expr) represents a lambda function similar to Python's 'lambda x: expr'. A function of several variables is written as Lambda((x, y, ...), expr). A simple example: >>> from sympy import Lambda >>> from sympy.abc import x >>> f = Lambda(x, x2) >>> f(4) 16 For multivariate functions, use: >>> from sympy.abc import y, z, t >>> f2 = Lambda((x, y, z, t), x + yz + tz) >>> f2(1, 2, 3, 4) 73 A handy shortcut for lots of arguments: >>> p = x, y, z >>> f = Lambda(p, x + yz) >>> f(p) x + yz """ is_Function = True def __new__(cls, variables, expr): from sympy.sets.sets import FiniteSet v = list(variables) if iterable(variables) else [variables] for i in v: if not getattr(i, 'is_symbol', False): raise TypeError('variable is not a symbol: %s' % i) if len(v) == 1 and v[0] == expr: return S.IdentityFunction obj = Expr.__new__(cls, Tuple(v), sympify(expr)) obj.nargs = FiniteSet(len(v)) return obj @property def variables(self): """The variables used in the internal representation of the function""" return self._args[0] bound_symbols = variables @property def expr(self): """The return value of the function""" return self._args[1] @property def free_symbols(self): return self.expr.free_symbols - set(self.variables) def __call__(self, args): n = len(args) if n not in self.nargs: # Lambda only ever has 1 value in nargs # XXX: exception message must be in exactly this format to # make it work with NumPy's functions like vectorize(). See, # for example, https://github.com/numpy/numpy/issues/1697. # The ideal solution would be just to attach metadata to # the exception and change NumPy to take advantage of this. ## XXX does this apply to Lambda? If not, remove this comment. temp = ('%(name)s takes exactly %(args)s ' 'argument%(plural)s (%(given)s given)') raise TypeError(temp % { 'name': self, 'args': list(self.nargs)[0], 'plural': 's'(list(self.nargs)[0] != 1), 'given': n}) return self.expr.xreplace(dict(list(zip(self.variables, args)))) def __eq__(self, other): if not isinstance(other, Lambda): return False if self.nargs != other.nargs: return False selfexpr = self.args[1] otherexpr = other.args[1] otherexpr = otherexpr.xreplace(dict(list(zip(other.args[0], self.args[0])))) return selfexpr == otherexpr def __ne__(self, other): return not(self == other) def __hash__(self): return super(Lambda, self).__hash__() def _hashable_content(self): return (self.expr.xreplace(self.canonical_variables),) @property def is_identity(self): """Return ``True`` if this ``Lambda`` is an identity function. """ if len(self.args) == 2: return self.args[0] == self.args[1] else: return None class Subs(Expr): """ Represents unevaluated substitutions of an expression. ``Subs(expr, x, x0)`` receives 3 arguments: an expression, a variable or list of distinct variables and a point or list of evaluation points corresponding to those variables. ``Subs`` objects are generally useful to represent unevaluated derivatives calculated at a point. The variables may be expressions, but they are subjected to the limitations of subs(), so it is usually a good practice to use only symbols for variables, since in that case there can be no ambiguity. There's no automatic expansion - use the method .doit() to effect all possible substitutions of the object and also of objects inside the expression. When evaluating derivatives at a point that is not a symbol, a Subs object is returned. One is also able to calculate derivatives of Subs objects - in this case the expression is always expanded (for the unevaluated form, use Derivative()). Examples ======== >>> from sympy import Subs, Function, sin, cos >>> from sympy.abc import x, y, z >>> f = Function('f') Subs are created when a particular substitution cannot be made. The x in the derivative cannot be replaced with 0 because 0 is not a valid variables of differentiation: >>> f(x).diff(x).subs(x, 0) Subs(Derivative(f(x), x), x, 0) Once f is known, the derivative and evaluation at 0 can be done: >>> _.subs(f, sin).doit() == sin(x).diff(x).subs(x, 0) == cos(0) True Subs can also be created directly with one or more variables: >>> Subs(f(x)sin(y) + z, (x, y), (0, 1)) Subs(z + f(x)sin(y), (x, y), (0, 1)) >>> _.doit() z + f(0)sin(1) Notes ===== In order to allow expressions to combine before doit is done, a representation of the Subs expression is used internally to make expressions that are superficially different compare the same: >>> a, b = Subs(x, x, 0), Subs(y, y, 0) >>> a + b 2Subs(x, x, 0) This can lead to unexpected consequences when using methods like `has` that are cached: >>> s = Subs(x, x, 0) >>> s.has(x), s.has(y) (True, False) >>> ss = s.subs(x, y) >>> ss.has(x), ss.has(y) (True, False) >>> s, ss (Subs(x, x, 0), Subs(y, y, 0)) """ def __new__(cls, expr, variables, point, assumptions): from sympy import Symbol if not is_sequence(variables, Tuple): variables = [variables] variables = Tuple(variables) if has_dups(variables): repeated = [str(v) for v, i in Counter(variables).items() if i > 1] __ = ', '.join(repeated) raise ValueError(filldedent(''' The following expressions appear more than once: %s ''' % __)) point = Tuple((point if is_sequence(point, Tuple) else [point])) if len(point) != len(variables): raise ValueError('Number of point values must be the same as ' 'the number of variables.') if not point: return sympify(expr) # denest if isinstance(expr, Subs): variables = expr.variables + variables point = expr.point + point expr = expr.expr else: expr = sympify(expr) # use symbols with names equal to the point value (with preppended _) # to give a variable-independent expression pre = "_" pts = sorted(set(point), key=default_sort_key) from sympy.printing import StrPrinter class CustomStrPrinter(StrPrinter): def _print_Dummy(self, expr): return str(expr) + str(expr.dummy_index) def mystr(expr, settings): p = CustomStrPrinter(settings) return p.doprint(expr) while 1: s_pts = {p: Symbol(pre + mystr(p)) for p in pts} reps = [(v, s_pts[p]) for v, p in zip(variables, point)] # if any underscore-preppended symbol is already a free symbol # and is a variable with a different point value, then there # is a clash, e.g. _0 clashes in Subs(_0 + _1, (_0, _1), (1, 0)) # because the new symbol that would be created is _1 but _1 # is already mapped to 0 so __0 and __1 are used for the new # symbols if any(r in expr.free_symbols and r in variables and Symbol(pre + mystr(point[variables.index(r)])) != r for _, r in reps): pre += "_" continue break obj = Expr.__new__(cls, expr, Tuple(variables), point) obj._expr = expr.xreplace(dict(reps)) return obj def _eval_is_commutative(self): return self.expr.is_commutative def doit(self, *hints): e, v, p = self.args # remove self mappings for i, (vi, pi) in enumerate(zip(v, p)): if vi == pi: v = v[:i] + v[i + 1:] p = p[:i] + p[i + 1:] if not v: return self.expr if isinstance(e, Derivative): # apply functions first, e.g. f -> cos undone = [] for i, vi in enumerate(v): if isinstance(vi, FunctionClass): e = e.subs(vi, p[i]) else: undone.append((vi, p[i])) if not isinstance(e, Derivative): e = e.doit() if isinstance(e, Derivative): # do Subs that aren't related to differentiation undone2 = [] D = Dummy() for vi, pi in undone: if D not in e.xreplace({vi: D}).free_symbols: e = e.subs(vi, pi) else: undone2.append((vi, pi)) undone = undone2 # differentiate wrt variables that are present wrt = [] D = Dummy() expr = e.expr free = expr.free_symbols for vi, ci in e.variable_count: if isinstance(vi, Symbol) and vi in free: expr = expr.diff((vi, ci)) elif D in expr.subs(vi, D).free_symbols: expr = expr.diff((vi, ci)) else: wrt.append((vi, ci)) # inject remaining subs rv = expr.subs(undone) # do remaining differentiation in order given* for vc in wrt: rv = rv.diff(vc) else: # inject remaining subs rv = e.subs(undone) else: rv = e.doit(hints).subs(list(zip(v, p))) if hints.get('deep', True) and rv != self: rv = rv.doit(hints) return rv def evalf(self, prec=None, options): return self.doit().evalf(prec, options) n = evalf @property def variables(self): """The variables to be evaluated""" return self._args[1] bound_symbols = variables @property def expr(self): """The expression on which the substitution operates""" return self._args[0] @property def point(self): """The values for which the variables are to be substituted""" return self._args[2] @property def free_symbols(self): return (self.expr.free_symbols - set(self.variables) \| set(self.point.free_symbols)) @property def expr_free_symbols(self): return (self.expr.expr_free_symbols - set(self.variables) \| set(self.point.expr_free_symbols)) def __eq__(self, other): if not isinstance(other, Subs): return False return self._hashable_content() == other._hashable_content() def __ne__(self, other): return not(self == other) def __hash__(self): return super(Subs, self).__hash__() def _hashable_content(self): return (self._expr.xreplace(self.canonical_variables), ) + tuple(ordered([(v, p) for v, p in zip(self.variables, self.point) if not self.expr.has(v)])) def _eval_subs(self, old, new): # Subs doit will do the variables in order; the semantics # of subs for Subs is have the following invariant for # Subs object foo: # foo.doit().subs(reps) == foo.subs(reps).doit() pt = list(self.point) if old in self.variables: if _atomic(new) == set([new]) and not any( i.has(new) for i in self.args): # the substitution is neutral return self.xreplace({old: new}) # any occurance of old before this point will get # handled by replacements from here on i = self.variables.index(old) for j in range(i, len(self.variables)): pt[j] = pt[j]._subs(old, new) return self.func(self.expr, self.variables, pt) v = [i._subs(old, new) for i in self.variables] if v != list(self.variables): return self.func(self.expr, self.variables + (old,), pt + [new]) expr = self.expr._subs(old, new) pt = [i._subs(old, new) for i in self.point] return self.func(expr, v, pt) def _eval_derivative(self, s): # Apply the chain rule of the derivative on the substitution variables: val = Add.fromiter(p.diff(s) * Subs(self.expr.diff(v), self.variables, self.point).doit() for v, p in zip(self.variables, self.point)) # Check if there are free symbols in `self.expr`: # First get the `expr_free_symbols`, which returns the free symbols # that are directly contained in an expression node (i.e. stop # searching if the node isn't an expression). At this point turn the # expressions into `free_symbols` and check if there are common free # symbols in `self.expr` and the deriving factor. fs1 = {j for i in self.expr_free_symbols for j in i.free_symbols} if len(fs1 & s.free_symbols) > 0: val += Subs(self.expr.diff(s), self.variables, self.point).doit() return val def _eval_nseries(self, x, n, logx): if x in self.point: # x is the variable being substituted into apos = self.point.index(x) other = self.variables[apos] else: other = x arg = self.expr.nseries(other, n=n, logx=logx) o = arg.getO() terms = Add.make_args(arg.removeO()) rv = Add([self.func(a, self.args[1:]) for a in terms]) if o: rv += o.subs(other, x) return rv def _eval_as_leading_term(self, x): if x in self.point: ipos = self.point.index(x) xvar = self.variables[ipos] return self.expr.as_leading_term(xvar) if x in self.variables: # if `x` is a dummy variable, it means it won't exist after the # substitution has been performed: return self # The variable is independent of the substitution: return self.expr.as_leading_term(x) def diff(f, symbols, kwargs): """ Differentiate f with respect to symbols. This is just a wrapper to unify .diff() and the Derivative class; its interface is similar to that of integrate(). You can use the same shortcuts for multiple variables as with Derivative. For example, diff(f(x), x, x, x) and diff(f(x), x, 3) both return the third derivative of f(x). You can pass evaluate=False to get an unevaluated Derivative class. Note that if there are 0 symbols (such as diff(f(x), x, 0), then the result will be the function (the zeroth derivative), even if evaluate=False. Examples ======== >>> from sympy import sin, cos, Function, diff >>> from sympy.abc import x, y >>> f = Function('f') >>> diff(sin(x), x) cos(x) >>> diff(f(x), x, x, x) Derivative(f(x), (x, 3)) >>> diff(f(x), x, 3) Derivative(f(x), (x, 3)) >>> diff(sin(x)cos(y), x, 2, y, 2) sin(x)cos(y) >>> type(diff(sin(x), x)) cos >>> type(diff(sin(x), x, evaluate=False)) <class 'sympy.core.function.Derivative'> >>> type(diff(sin(x), x, 0)) sin >>> type(diff(sin(x), x, 0, evaluate=False)) sin >>> diff(sin(x)) cos(x) >>> diff(sin(xy)) Traceback (most recent call last): ... ValueError: specify differentiation variables to differentiate sin(xy) Note that ``diff(sin(x))`` syntax is meant only for convenience in interactive sessions and should be avoided in library code. References ========== http://reference.wolfram.com/legacy/v5_2/Built-inFunctions/AlgebraicComputation/Calculus/D.html See Also ======== Derivative sympy.geometry.util.idiff: computes the derivative implicitly """ if hasattr(f, 'diff'): return f.diff(symbols, *kwargs) kwargs.setdefault('evaluate', True) return Derivative(f, symbols, kwargs) def expand(e, deep=True, modulus=None, power_base=True, power_exp=True, mul=True, log=True, multinomial=True, basic=True, hints): r""" Expand an expression using methods given as hints. Hints evaluated unless explicitly set to False are: ``basic``, ``log``, ``multinomial``, ``mul``, ``power_base``, and ``power_exp`` The following hints are supported but not applied unless set to True: ``complex``, ``func``, and ``trig``. In addition, the following meta-hints are supported by some or all of the other hints: ``frac``, ``numer``, ``denom``, ``modulus``, and ``force``. ``deep`` is supported by all hints. Additionally, subclasses of Expr may define their own hints or meta-hints. The ``basic`` hint is used for any special rewriting of an object that should be done automatically (along with the other hints like ``mul``) when expand is called. This is a catch-all hint to handle any sort of expansion that may not be described by the existing hint names. To use this hint an object should override the ``_eval_expand_basic`` method. Objects may also define their own expand methods, which are not run by default. See the API section below. If ``deep`` is set to ``True`` (the default), things like arguments of functions are recursively expanded. Use ``deep=False`` to only expand on the top level. If the ``force`` hint is used, assumptions about variables will be ignored in making the expansion. Hints ===== These hints are run by default mul --- Distributes multiplication over addition: >>> from sympy import cos, exp, sin >>> from sympy.abc import x, y, z >>> (y(x + z)).expand(mul=True) xy + yz multinomial ----------- Expand (x + y + ...)n where n is a positive integer. >>> ((x + y + z)2).expand(multinomial=True) x2 + 2xy + 2xz + y2 + 2yz + z2 power_exp --------- Expand addition in exponents into multiplied bases. >>> exp(x + y).expand(power_exp=True) exp(x)exp(y) >>> (2(x + y)).expand(power_exp=True) 2x2y power_base ---------- Split powers of multiplied bases. This only happens by default if assumptions allow, or if the ``force`` meta-hint is used: >>> ((xy)*z).expand(power_base=True) (xy)*z >>> ((xy)z).expand(power_base=True, force=True) xzyz >>> ((2y)z).expand(power_base=True) 2zyz Note that in some cases where this expansion always holds, SymPy performs it automatically: >>> (xy)2 x2y2 log --- Pull out power of an argument as a coefficient and split logs products into sums of logs. Note that these only work if the arguments of the log function have the proper assumptions--the arguments must be positive and the exponents must be real--or else the ``force`` hint must be True: >>> from sympy import log, symbols >>> log(x2y).expand(log=True) log(x*2y) >>> log(x*2y).expand(log=True, force=True) 2log(x) + log(y) >>> x, y = symbols('x,y', positive=True) >>> log(x2y).expand(log=True) 2log(x) + log(y) basic ----- This hint is intended primarily as a way for custom subclasses to enable expansion by default. These hints are not run by default: complex ------- Split an expression into real and imaginary parts. >>> x, y = symbols('x,y') >>> (x + y).expand(complex=True) re(x) + re(y) + Iim(x) + Iim(y) >>> cos(x).expand(complex=True) -Isin(re(x))sinh(im(x)) + cos(re(x))cosh(im(x)) Note that this is just a wrapper around ``as_real_imag()``. Most objects that wish to redefine ``_eval_expand_complex()`` should consider redefining ``as_real_imag()`` instead. func ---- Expand other functions. >>> from sympy import gamma >>> gamma(x + 1).expand(func=True) xgamma(x) trig ---- Do trigonometric expansions. >>> cos(x + y).expand(trig=True) -sin(x)sin(y) + cos(x)cos(y) >>> sin(2x).expand(trig=True) 2sin(x)cos(x) Note that the forms of ``sin(nx)`` and ``cos(nx)`` in terms of ``sin(x)`` and ``cos(x)`` are not unique, due to the identity `\sin^2(x) + \cos^2(x) = 1`. The current implementation uses the form obtained from Chebyshev polynomials, but this may change. See `this MathWorld article <http://mathworld.wolfram.com/Multiple-AngleFormulas.html>`_ for more information. Notes ===== - You can shut off unwanted methods:: >>> (exp(x + y)(x + y)).expand() xexp(x)exp(y) + yexp(x)exp(y) >>> (exp(x + y)(x + y)).expand(power_exp=False) xexp(x + y) + yexp(x + y) >>> (exp(x + y)(x + y)).expand(mul=False) (x + y)exp(x)exp(y) - Use deep=False to only expand on the top level:: >>> exp(x + exp(x + y)).expand() exp(x)exp(exp(x)exp(y)) >>> exp(x + exp(x + y)).expand(deep=False) exp(x)exp(exp(x + y)) - Hints are applied in an arbitrary, but consistent order (in the current implementation, they are applied in alphabetical order, except multinomial comes before mul, but this may change). Because of this, some hints may prevent expansion by other hints if they are applied first. For example, ``mul`` may distribute multiplications and prevent ``log`` and ``power_base`` from expanding them. Also, if ``mul`` is applied before ``multinomial`, the expression might not be fully distributed. The solution is to use the various ``expand_hint`` helper functions or to use ``hint=False`` to this function to finely control which hints are applied. Here are some examples:: >>> from sympy import expand, expand_mul, expand_power_base >>> x, y, z = symbols('x,y,z', positive=True) >>> expand(log(x(y + z))) log(x) + log(y + z) Here, we see that ``log`` was applied before ``mul``. To get the mul expanded form, either of the following will work:: >>> expand_mul(log(x(y + z))) log(xy + xz) >>> expand(log(x(y + z)), log=False) log(xy + xz) A similar thing can happen with the ``power_base`` hint:: >>> expand((x(y + z))*x) (xy + xz)x To get the ``power_base`` expanded form, either of the following will work:: >>> expand((x(y + z))x, mul=False) xx(y + z)x >>> expand_power_base((x(y + z))x) xx(y + z)x >>> expand((x + y)y/x) y + y*2/x The parts of a rational expression can be targeted:: >>> expand((x + y)y/x/(x + 1), frac=True) (xy + y2)/(x2 + x) >>> expand((x + y)y/x/(x + 1), numer=True) (xy + y2)/(x(x + 1)) >>> expand((x + y)y/x/(x + 1), denom=True) y(x + y)/(x*2 + x) - The ``modulus`` meta-hint can be used to reduce the coefficients of an expression post-expansion:: >>> expand((3x + 1)*2) 9x*2 + 6x + 1 >>> expand((3x + 1)2, modulus=5) 4x2 + x + 1 - Either ``expand()`` the function or ``.expand()`` the method can be used. Both are equivalent:: >>> expand((x + 1)2) x*2 + 2x + 1 >>> ((x + 1)2).expand() x2 + 2x + 1 API === Objects can define their own expand hints by defining ``_eval_expand_hint()``. The function should take the form:: def _eval_expand_hint(self, hints): # Only apply the method to the top-level expression ... See also the example below. Objects should define ``_eval_expand_hint()`` methods only if ``hint`` applies to that specific object. The generic ``_eval_expand_hint()`` method defined in Expr will handle the no-op case. Each hint should be responsible for expanding that hint only. Furthermore, the expansion should be applied to the top-level expression only. ``expand()`` takes care of the recursion that happens when ``deep=True``. You should only call ``_eval_expand_hint()`` methods directly if you are 100% sure that the object has the method, as otherwise you are liable to get unexpected ``AttributeError``s. Note, again, that you do not need to recursively apply the hint to args of your object: this is handled automatically by ``expand()``. ``_eval_expand_hint()`` should generally not be used at all outside of an ``_eval_expand_hint()`` method. If you want to apply a specific expansion from within another method, use the public ``expand()`` function, method, or ``expand_hint()`` functions. In order for expand to work, objects must be rebuildable by their args, i.e., ``obj.func(obj.args) == obj`` must hold. Expand methods are passed ``*hints`` so that expand hints may use 'metahints'--hints that control how different expand methods are applied. For example, the ``force=True`` hint described above that causes ``expand(log=True)`` to ignore assumptions is such a metahint. The ``deep`` meta-hint is handled exclusively by ``expand()`` and is not passed to ``_eval_expand_hint()`` methods. Note that expansion hints should generally be methods that perform some kind of 'expansion'. For hints that simply rewrite an expression, use the .rewrite() API. Examples ======== >>> from sympy import Expr, sympify >>> class MyClass(Expr): ... def __new__(cls, args): ... args = sympify(args) ... return Expr.__new__(cls, args) ... ... def _eval_expand_double(self, hints): ... ''' ... Doubles the args of MyClass. ... ... If there more than four args, doubling is not performed, ... unless force=True is also used (False by default). ... ''' ... force = hints.pop('force', False) ... if not force and len(self.args) > 4: ... return self ... return self.func((self.args + self.args)) ... >>> a = MyClass(1, 2, MyClass(3, 4)) >>> a MyClass(1, 2, MyClass(3, 4)) >>> a.expand(double=True) MyClass(1, 2, MyClass(3, 4, 3, 4), 1, 2, MyClass(3, 4, 3, 4)) >>> a.expand(double=True, deep=False) MyClass(1, 2, MyClass(3, 4), 1, 2, MyClass(3, 4)) >>> b = MyClass(1, 2, 3, 4, 5) >>> b.expand(double=True) MyClass(1, 2, 3, 4, 5) >>> b.expand(double=True, force=True) MyClass(1, 2, 3, 4, 5, 1, 2, 3, 4, 5) See Also ======== expand_log, expand_mul, expand_multinomial, expand_complex, expand_trig, expand_power_base, expand_power_exp, expand_func, hyperexpand """ # don't modify this; modify the Expr.expand method hints['power_base'] = power_base hints['power_exp'] = power_exp hints['mul'] = mul hints['log'] = log hints['multinomial'] = multinomial hints['basic'] = basic return sympify(e).expand(deep=deep, modulus=modulus, *hints) # This is a special application of two hints def _mexpand(expr, recursive=False): # expand multinomials and then expand products; this may not always # be sufficient to give a fully expanded expression (see # test_issue_8247_8354 in test_arit) if expr is None: return was = None while was != expr: was, expr = expr, expand_mul(expand_multinomial(expr)) if not recursive: break return expr # These are simple wrappers around single hints. def expand_mul(expr, deep=True): """ Wrapper around expand that only uses the mul hint. See the expand docstring for more information. Examples ======== >>> from sympy import symbols, expand_mul, exp, log >>> x, y = symbols('x,y', positive=True) >>> expand_mul(exp(x+y)(x+y)log(xy*2)) xexp(x + y)log(xy*2) + yexp(x + y)log(xy2) """ return sympify(expr).expand(deep=deep, mul=True, power_exp=False, power_base=False, basic=False, multinomial=False, log=False) def expand_multinomial(expr, deep=True): """ Wrapper around expand that only uses the multinomial hint. See the expand docstring for more information. Examples ======== >>> from sympy import symbols, expand_multinomial, exp >>> x, y = symbols('x y', positive=True) >>> expand_multinomial((x + exp(x + 1))2) x*2 + 2xexp(x + 1) + exp(2x + 2) """ return sympify(expr).expand(deep=deep, mul=False, power_exp=False, power_base=False, basic=False, multinomial=True, log=False) def expand_log(expr, deep=True, force=False): """ Wrapper around expand that only uses the log hint. See the expand docstring for more information. Examples ======== >>> from sympy import symbols, expand_log, exp, log >>> x, y = symbols('x,y', positive=True) >>> expand_log(exp(x+y)(x+y)log(xy2)) (x + y)(log(x) + 2log(y))exp(x + y) """ return sympify(expr).expand(deep=deep, log=True, mul=False, power_exp=False, power_base=False, multinomial=False, basic=False, force=force) def expand_func(expr, deep=True): """ Wrapper around expand that only uses the func hint. See the expand docstring for more information. Examples ======== >>> from sympy import expand_func, gamma >>> from sympy.abc import x >>> expand_func(gamma(x + 2)) x(x + 1)gamma(x) """ return sympify(expr).expand(deep=deep, func=True, basic=False, log=False, mul=False, power_exp=False, power_base=False, multinomial=False) def expand_trig(expr, deep=True): """ Wrapper around expand that only uses the trig hint. See the expand docstring for more information. Examples ======== >>> from sympy import expand_trig, sin >>> from sympy.abc import x, y >>> expand_trig(sin(x+y)(x+y)) (x + y)(sin(x)cos(y) + sin(y)cos(x)) """ return sympify(expr).expand(deep=deep, trig=True, basic=False, log=False, mul=False, power_exp=False, power_base=False, multinomial=False) def expand_complex(expr, deep=True): """ Wrapper around expand that only uses the complex hint. See the expand docstring for more information. Examples ======== >>> from sympy import expand_complex, exp, sqrt, I >>> from sympy.abc import z >>> expand_complex(exp(z)) Iexp(re(z))sin(im(z)) + exp(re(z))cos(im(z)) >>> expand_complex(sqrt(I)) sqrt(2)/2 + sqrt(2)I/2 See Also ======== Expr.as_real_imag """ return sympify(expr).expand(deep=deep, complex=True, basic=False, log=False, mul=False, power_exp=False, power_base=False, multinomial=False) def expand_power_base(expr, deep=True, force=False): """ Wrapper around expand that only uses the power_base hint. See the expand docstring for more information. A wrapper to expand(power_base=True) which separates a power with a base that is a Mul into a product of powers, without performing any other expansions, provided that assumptions about the power's base and exponent allow. deep=False (default is True) will only apply to the top-level expression. force=True (default is False) will cause the expansion to ignore assumptions about the base and exponent. When False, the expansion will only happen if the base is non-negative or the exponent is an integer. >>> from sympy.abc import x, y, z >>> from sympy import expand_power_base, sin, cos, exp >>> (xy)2 x2y*2 >>> (2x)*y (2x)y >>> expand_power_base(_) 2yxy >>> expand_power_base((xy)*z) (xy)*z >>> expand_power_base((xy)z, force=True) xzyz >>> expand_power_base(sin((xy)*z), deep=False) sin((xy)*z) >>> expand_power_base(sin((xy)z), force=True) sin(xzyz) >>> expand_power_base((2sin(x))*y + (2cos(x))y) 2ysin(x)y + 2ycos(x)*y >>> expand_power_base((2exp(y))x) 2xexp(y)x >>> expand_power_base((2cos(x))y) 2ycos(x)y Notice that sums are left untouched. If this is not the desired behavior, apply full ``expand()`` to the expression: >>> expand_power_base(((x+y)z)2) z2(x + y)2 >>> (((x+y)z)2).expand() x2z2 + 2xyz2 + y2z2 >>> expand_power_base((2y)(1+z)) 2(z + 1)y(z + 1) >>> ((2y)*(1+z)).expand() 22*zyyz """ return sympify(expr).expand(deep=deep, log=False, mul=False, power_exp=False, power_base=True, multinomial=False, basic=False, force=force) def expand_power_exp(expr, deep=True): """ Wrapper around expand that only uses the power_exp hint. See the expand docstring for more information. Examples ======== >>> from sympy import expand_power_exp >>> from sympy.abc import x, y >>> expand_power_exp(x(y + 2)) x2xy """ return sympify(expr).expand(deep=deep, complex=False, basic=False, log=False, mul=False, power_exp=True, power_base=False, multinomial=False) def count_ops(expr, visual=False): """ Return a representation (integer or expression) of the operations in expr. If ``visual`` is ``False`` (default) then the sum of the coefficients of the visual expression will be returned. If ``visual`` is ``True`` then the number of each type of operation is shown with the core class types (or their virtual equivalent) multiplied by the number of times they occur. If expr is an iterable, the sum of the op counts of the items will be returned. Examples ======== >>> from sympy.abc import a, b, x, y >>> from sympy import sin, count_ops Although there isn't a SUB object, minus signs are interpreted as either negations or subtractions: >>> (x - y).count_ops(visual=True) SUB >>> (-x).count_ops(visual=True) NEG Here, there are two Adds and a Pow: >>> (1 + a + b2).count_ops(visual=True) 2ADD + POW In the following, an Add, Mul, Pow and two functions: >>> (sin(x)x + sin(x)*2).count_ops(visual=True) ADD + MUL + POW + 2SIN for a total of 5: >>> (sin(x)x + sin(x)2).count_ops(visual=False) 5 Note that "what you type" is not always what you get. The expression 1/x/y is translated by sympy into 1/(xy) so it gives a DIV and MUL rather than two DIVs: >>> (1/x/y).count_ops(visual=True) DIV + MUL The visual option can be used to demonstrate the difference in operations for expressions in different forms. Here, the Horner representation is compared with the expanded form of a polynomial: >>> eq=x(1 + x(2 + x(3 + x))) >>> count_ops(eq.expand(), visual=True) - count_ops(eq, visual=True) -MUL + 3POW The count_ops function also handles iterables: >>> count_ops([x, sin(x), None, True, x + 2], visual=False) 2 >>> count_ops([x, sin(x), None, True, x + 2], visual=True) ADD + SIN >>> count_ops({x: sin(x), x + 2: y + 1}, visual=True) 2ADD + SIN """ from sympy import Integral, Symbol from sympy.core.relational import Relational from sympy.simplify.radsimp import fraction from sympy.logic.boolalg import BooleanFunction from sympy.utilities.misc import func_name expr = sympify(expr) if isinstance(expr, Expr) and not expr.is_Relational: ops = [] args = [expr] NEG = Symbol('NEG') DIV = Symbol('DIV') SUB = Symbol('SUB') ADD = Symbol('ADD') while args: a = args.pop() # XXX: This is a hack to support non-Basic args if isinstance(a, string_types): continue if a.is_Rational: #-1/3 = NEG + DIV if a is not S.One: if a.p < 0: ops.append(NEG) if a.q != 1: ops.append(DIV) continue elif a.is_Mul or a.is_MatMul: if _coeff_isneg(a): ops.append(NEG) if a.args[0] is S.NegativeOne: a = a.as_two_terms()[1] else: a = -a n, d = fraction(a) if n.is_Integer: ops.append(DIV) if n < 0: ops.append(NEG) args.append(d) continue # won't be -Mul but could be Add elif d is not S.One: if not d.is_Integer: args.append(d) ops.append(DIV) args.append(n) continue # could be -Mul elif a.is_Add or a.is_MatAdd: aargs = list(a.args) negs = 0 for i, ai in enumerate(aargs): if _coeff_isneg(ai): negs += 1 args.append(-ai) if i > 0: ops.append(SUB) else: args.append(ai) if i > 0: ops.append(ADD) if negs == len(aargs): # -x - y = NEG + SUB ops.append(NEG) elif _coeff_isneg(aargs[0]): # -x + y = SUB, but already recorded ADD ops.append(SUB - ADD) continue if a.is_Pow and a.exp is S.NegativeOne: ops.append(DIV) args.append(a.base) # won't be -Mul but could be Add continue if (a.is_Mul or a.is_Pow or a.is_Function or isinstance(a, Derivative) or isinstance(a, Integral)): o = Symbol(a.func.__name__.upper()) # count the args if (a.is_Mul or isinstance(a, LatticeOp)): ops.append(o(len(a.args) - 1)) else: ops.append(o) if not a.is_Symbol: args.extend(a.args) elif type(expr) is dict: ops = [count_ops(k, visual=visual) + count_ops(v, visual=visual) for k, v in expr.items()] elif iterable(expr): ops = [count_ops(i, visual=visual) for i in expr] elif isinstance(expr, (Relational, BooleanFunction)): ops = [] for arg in expr.args: ops.append(count_ops(arg, visual=True)) o = Symbol(func_name(expr, short=True).upper()) ops.append(o) elif not isinstance(expr, Basic): ops = [] else: # it's Basic not isinstance(expr, Expr): if not isinstance(expr, Basic): raise TypeError("Invalid type of expr") else: ops = [] args = [expr] while args: a = args.pop() # XXX: This is a hack to support non-Basic args if isinstance(a, string_types): continue if a.args: o = Symbol(a.func.__name__.upper()) if a.is_Boolean: ops.append(o(len(a.args)-1)) else: ops.append(o) args.extend(a.args) if not ops: if visual: return S.Zero return 0 ops = Add(ops) if visual: return ops if ops.is_Number: return int(ops) return sum(int((a.args or [1])[0]) for a in Add.make_args(ops)) def nfloat(expr, n=15, exponent=False): """Make all Rationals in expr Floats except those in exponents (unless the exponents flag is set to True). Examples ======== >>> from sympy.core.function import nfloat >>> from sympy.abc import x, y >>> from sympy import cos, pi, sqrt >>> nfloat(x4 + x/2 + cos(pi/3) + 1 + sqrt(y)) x4 + 0.5x + sqrt(y) + 1.5 >>> nfloat(x4 + sqrt(y), exponent=True) x4.0 + y0.5 """ from sympy.core.power import Pow from sympy.polys.rootoftools import RootOf if iterable(expr, exclude=string_types): if isinstance(expr, (dict, Dict)): return type(expr)([(k, nfloat(v, n, exponent)) for k, v in list(expr.items())]) return type(expr)([nfloat(a, n, exponent) for a in expr]) rv = sympify(expr) if rv.is_Number: return Float(rv, n) elif rv.is_number: # evalf doesn't always set the precision rv = rv.n(n) if rv.is_Number: rv = Float(rv.n(n), n) else: pass # pure_complex(rv) is likely True return rv # watch out for RootOf instances that don't like to have # their exponents replaced with Dummies and also sometimes have # problems with evaluating at low precision (issue 6393) rv = rv.xreplace({ro: ro.n(n) for ro in rv.atoms(RootOf)}) if not exponent: reps = [(p, Pow(p.base, Dummy())) for p in rv.atoms(Pow)] rv = rv.xreplace(dict(reps)) rv = rv.n(n) if not exponent: rv = rv.xreplace({d.exp: p.exp for p, d in reps}) else: # Pow._eval_evalf special cases Integer exponents so if # exponent is suppose to be handled we have to do so here rv = rv.xreplace(Transform( lambda x: Pow(x.base, Float(x.exp, n)), lambda x: x.is_Pow and x.exp.is_Integer)) return rv.xreplace(Transform( lambda x: x.func(nfloat(x.args, n, exponent)), lambda x: isinstance(x, Function))) from sympy.core.symbol import Dummy, Symbol
ddd2493ea1aae6cc2fb7fe0ab47b0ef3e9a18b9eb7a766bb8b45e24981937b48	from __future__ import print_function, division from collections import defaultdict from functools import cmp_to_key from .basic import Basic from .compatibility import reduce, is_sequence, range from .logic import _fuzzy_group, fuzzy_or, fuzzy_not from .singleton import S from .operations import AssocOp from .cache import cacheit from .numbers import ilcm, igcd from .expr import Expr # Key for sorting commutative args in canonical order _args_sortkey = cmp_to_key(Basic.compare) def _addsort(args): # in-place sorting of args args.sort(key=_args_sortkey) def _unevaluated_Add(args): """Return a well-formed unevaluated Add: Numbers are collected and put in slot 0 and args are sorted. Use this when args have changed but you still want to return an unevaluated Add. Examples ======== >>> from sympy.core.add import _unevaluated_Add as uAdd >>> from sympy import S, Add >>> from sympy.abc import x, y >>> a = uAdd([S(1.0), x, S(2)]) >>> a.args[0] 3.00000000000000 >>> a.args[1] x Beyond the Number being in slot 0, there is no other assurance of order for the arguments since they are hash sorted. So, for testing purposes, output produced by this in some other function can only be tested against the output of this function or as one of several options: >>> opts = (Add(x, y, evaluated=False), Add(y, x, evaluated=False)) >>> a = uAdd(x, y) >>> assert a in opts and a == uAdd(x, y) >>> uAdd(x + 1, x + 2) x + x + 3 """ args = list(args) newargs = [] co = S.Zero while args: a = args.pop() if a.is_Add: # this will keep nesting from building up # so that x + (x + 1) -> x + x + 1 (3 args) args.extend(a.args) elif a.is_Number: co += a else: newargs.append(a) _addsort(newargs) if co: newargs.insert(0, co) return Add._from_args(newargs) class Add(Expr, AssocOp): __slots__ = [] is_Add = True @classmethod def flatten(cls, seq): """ Takes the sequence "seq" of nested Adds and returns a flatten list. Returns: (commutative_part, noncommutative_part, order_symbols) Applies associativity, all terms are commutable with respect to addition. NB: the removal of 0 is already handled by AssocOp.__new__ See also ======== sympy.core.mul.Mul.flatten """ from sympy.calculus.util import AccumBounds from sympy.matrices.expressions import MatrixExpr from sympy.tensor.tensor import TensExpr rv = None if len(seq) == 2: a, b = seq if b.is_Rational: a, b = b, a if a.is_Rational: if b.is_Mul: rv = [a, b], [], None if rv: if all(s.is_commutative for s in rv[0]): return rv return [], rv[0], None terms = {} # term -> coeff # e.g. x*2 -> 5 for ... + 5x2 + ... coeff = S.Zero # coefficient (Number or zoo) to always be in slot 0 # e.g. 3 + ... order_factors = [] for o in seq: # O(x) if o.is_Order: for o1 in order_factors: if o1.contains(o): o = None break if o is None: continue order_factors = [o] + [ o1 for o1 in order_factors if not o.contains(o1)] continue # 3 or NaN elif o.is_Number: if (o is S.NaN or coeff is S.ComplexInfinity and o.is_finite is False): # we know for sure the result will be nan return [S.NaN], [], None if coeff.is_Number: coeff += o if coeff is S.NaN: # we know for sure the result will be nan return [S.NaN], [], None continue elif isinstance(o, AccumBounds): coeff = o.__add__(coeff) continue elif isinstance(o, MatrixExpr): # can't add 0 to Matrix so make sure coeff is not 0 coeff = o.__add__(coeff) if coeff else o continue elif isinstance(o, TensExpr): coeff = o.__add__(coeff) if coeff else o continue elif o is S.ComplexInfinity: if coeff.is_finite is False: # we know for sure the result will be nan return [S.NaN], [], None coeff = S.ComplexInfinity continue # Add([...]) elif o.is_Add: # NB: here we assume Add is always commutative seq.extend(o.args) # TODO zerocopy? continue # Mul([...]) elif o.is_Mul: c, s = o.as_coeff_Mul() # check for unevaluated Pow, e.g. 23 or 2(-1/2) elif o.is_Pow: b, e = o.as_base_exp() if b.is_Number and (e.is_Integer or (e.is_Rational and e.is_negative)): seq.append(be) continue c, s = S.One, o else: # everything else c = S.One s = o # now we have: # o = cs, where # # c is a Number # s is an expression with number factor extracted # let's collect terms with the same s, so e.g. # 2x*2 + 3x*2 -> 5x*2 if s in terms: terms[s] += c if terms[s] is S.NaN: # we know for sure the result will be nan return [S.NaN], [], None else: terms[s] = c # now let's construct new args: # [2x2, x3, 7x4, pi, ...] newseq = [] noncommutative = False for s, c in terms.items(): # 0s if c is S.Zero: continue # 1s elif c is S.One: newseq.append(s) # cs else: if s.is_Mul: # Mul, already keeps its arguments in perfect order. # so we can simply put c in slot0 and go the fast way. cs = s._new_rawargs(((c,) + s.args)) newseq.append(cs) elif s.is_Add: # we just re-create the unevaluated Mul newseq.append(Mul(c, s, evaluate=False)) else: # alternatively we have to call all Mul's machinery (slow) newseq.append(Mul(c, s)) noncommutative = noncommutative or not s.is_commutative # oo, -oo if coeff is S.Infinity: newseq = [f for f in newseq if not (f.is_nonnegative or f.is_real and f.is_finite)] elif coeff is S.NegativeInfinity: newseq = [f for f in newseq if not (f.is_nonpositive or f.is_real and f.is_finite)] if coeff is S.ComplexInfinity: # zoo might be # infinite_real + finite_im # finite_real + infinite_im # infinite_real + infinite_im # addition of a finite real or imaginary number won't be able to # change the zoo nature; adding an infinite qualtity would result # in a NaN condition if it had sign opposite of the infinite # portion of zoo, e.g., infinite_real - infinite_real. newseq = [c for c in newseq if not (c.is_finite and c.is_real is not None)] # process O(x) if order_factors: newseq2 = [] for t in newseq: for o in order_factors: # x + O(x) -> O(x) if o.contains(t): t = None break # x + O(x2) -> x + O(x2) if t is not None: newseq2.append(t) newseq = newseq2 + order_factors # 1 + O(1) -> O(1) for o in order_factors: if o.contains(coeff): coeff = S.Zero break # order args canonically _addsort(newseq) # current code expects coeff to be first if coeff is not S.Zero: newseq.insert(0, coeff) # we are done if noncommutative: return [], newseq, None else: return newseq, [], None @classmethod def class_key(cls): """Nice order of classes""" return 3, 1, cls.__name__ def as_coefficients_dict(a): """Return a dictionary mapping terms to their Rational coefficient. Since the dictionary is a defaultdict, inquiries about terms which were not present will return a coefficient of 0. If an expression is not an Add it is considered to have a single term. Examples ======== >>> from sympy.abc import a, x >>> (3x + ax + 4).as_coefficients_dict() {1: 4, x: 3, ax: 1} >>> _[a] 0 >>> (3ax).as_coefficients_dict() {ax: 3} """ d = defaultdict(list) for ai in a.args: c, m = ai.as_coeff_Mul() d[m].append(c) for k, v in d.items(): if len(v) == 1: d[k] = v[0] else: d[k] = Add(v) di = defaultdict(int) di.update(d) return di @cacheit def as_coeff_add(self, deps): """ Returns a tuple (coeff, args) where self is treated as an Add and coeff is the Number term and args is a tuple of all other terms. Examples ======== >>> from sympy.abc import x >>> (7 + 3x).as_coeff_add() (7, (3x,)) >>> (7x).as_coeff_add() (0, (7x,)) """ if deps: l1 = [] l2 = [] for f in self.args: if f.has(deps): l2.append(f) else: l1.append(f) return self._new_rawargs(l1), tuple(l2) coeff, notrat = self.args[0].as_coeff_add() if coeff is not S.Zero: return coeff, notrat + self.args[1:] return S.Zero, self.args def as_coeff_Add(self, rational=False): """Efficiently extract the coefficient of a summation. """ coeff, args = self.args[0], self.args[1:] if coeff.is_Number and not rational or coeff.is_Rational: return coeff, self._new_rawargs(args) return S.Zero, self # Note, we intentionally do not implement Add.as_coeff_mul(). Rather, we # let Expr.as_coeff_mul() just always return (S.One, self) for an Add. See # issue 5524. def _eval_power(self, e): if e.is_Rational and self.is_number: from sympy.core.evalf import pure_complex from sympy.core.mul import _unevaluated_Mul from sympy.core.exprtools import factor_terms from sympy.core.function import expand_multinomial from sympy.functions.elementary.complexes import sign from sympy.functions.elementary.miscellaneous import sqrt ri = pure_complex(self) if ri: r, i = ri if e.q == 2: D = sqrt(r2 + i2) if D.is_Rational: # (r, i, D) is a Pythagorean triple root = sqrt(factor_terms((D - r)/2))*e.p return rootexpand_multinomial(( # principle value (D + r)/abs(i) + sign(i)S.ImaginaryUnit)e.p) elif e == -1: return _unevaluated_Mul( r - iS.ImaginaryUnit, 1/(r2 + i2)) @cacheit def _eval_derivative(self, s): return self.func([a.diff(s) for a in self.args]) def _eval_nseries(self, x, n, logx): terms = [t.nseries(x, n=n, logx=logx) for t in self.args] return self.func(terms) def _matches_simple(self, expr, repl_dict): # handle (w+3).matches('x+5') -> {w: x+2} coeff, terms = self.as_coeff_add() if len(terms) == 1: return terms[0].matches(expr - coeff, repl_dict) return def matches(self, expr, repl_dict={}, old=False): return AssocOp._matches_commutative(self, expr, repl_dict, old) @staticmethod def _combine_inverse(lhs, rhs): """ Returns lhs - rhs, but treats oo like a symbol so oo - oo returns 0, instead of a nan. """ from sympy.core.function import expand_mul from sympy.core.symbol import Dummy inf = (S.Infinity, S.NegativeInfinity) if lhs.has(inf) or rhs.has(inf): oo = Dummy('oo') reps = { S.Infinity: oo, S.NegativeInfinity: -oo} ireps = dict([(v, k) for k, v in reps.items()]) eq = expand_mul(lhs.xreplace(reps) - rhs.xreplace(reps)) if eq.has(oo): eq = eq.replace( lambda x: x.is_Pow and x.base == oo, lambda x: x.base) return eq.xreplace(ireps) else: return expand_mul(lhs - rhs) @cacheit def as_two_terms(self): """Return head and tail of self. This is the most efficient way to get the head and tail of an expression. - if you want only the head, use self.args[0]; - if you want to process the arguments of the tail then use self.as_coef_add() which gives the head and a tuple containing the arguments of the tail when treated as an Add. - if you want the coefficient when self is treated as a Mul then use self.as_coeff_mul()[0] >>> from sympy.abc import x, y >>> (3x - 2y + 5).as_two_terms() (5, 3x - 2y) """ return self.args[0], self._new_rawargs(self.args[1:]) def as_numer_denom(self): # clear rational denominator content, expr = self.primitive() ncon, dcon = content.as_numer_denom() # collect numerators and denominators of the terms nd = defaultdict(list) for f in expr.args: ni, di = f.as_numer_denom() nd[di].append(ni) # check for quick exit if len(nd) == 1: d, n = nd.popitem() return self.func( [_keep_coeff(ncon, ni) for ni in n]), _keep_coeff(dcon, d) # sum up the terms having a common denominator for d, n in nd.items(): if len(n) == 1: nd[d] = n[0] else: nd[d] = self.func(n) # assemble single numerator and denominator denoms, numers = [list(i) for i in zip(iter(nd.items()))] n, d = self.func([Mul((denoms[:i] + [numers[i]] + denoms[i + 1:])) for i in range(len(numers))]), Mul(denoms) return _keep_coeff(ncon, n), _keep_coeff(dcon, d) def _eval_is_polynomial(self, syms): return all(term._eval_is_polynomial(syms) for term in self.args) def _eval_is_rational_function(self, syms): return all(term._eval_is_rational_function(syms) for term in self.args) def _eval_is_algebraic_expr(self, syms): return all(term._eval_is_algebraic_expr(syms) for term in self.args) # assumption methods _eval_is_real = lambda self: _fuzzy_group( (a.is_real for a in self.args), quick_exit=True) _eval_is_complex = lambda self: _fuzzy_group( (a.is_complex for a in self.args), quick_exit=True) _eval_is_antihermitian = lambda self: _fuzzy_group( (a.is_antihermitian for a in self.args), quick_exit=True) _eval_is_finite = lambda self: _fuzzy_group( (a.is_finite for a in self.args), quick_exit=True) _eval_is_hermitian = lambda self: _fuzzy_group( (a.is_hermitian for a in self.args), quick_exit=True) _eval_is_integer = lambda self: _fuzzy_group( (a.is_integer for a in self.args), quick_exit=True) _eval_is_rational = lambda self: _fuzzy_group( (a.is_rational for a in self.args), quick_exit=True) _eval_is_algebraic = lambda self: _fuzzy_group( (a.is_algebraic for a in self.args), quick_exit=True) _eval_is_commutative = lambda self: _fuzzy_group( a.is_commutative for a in self.args) def _eval_is_imaginary(self): nz = [] im_I = [] for a in self.args: if a.is_real: if a.is_zero: pass elif a.is_zero is False: nz.append(a) else: return elif a.is_imaginary: im_I.append(aS.ImaginaryUnit) elif (S.ImaginaryUnita).is_real: im_I.append(aS.ImaginaryUnit) else: return b = self.func(nz) if b.is_zero: return fuzzy_not(self.func(im_I).is_zero) elif b.is_zero is False: return False def _eval_is_zero(self): if self.is_commutative is False: # issue 10528: there is no way to know if a nc symbol # is zero or not return nz = [] z = 0 im_or_z = False im = False for a in self.args: if a.is_real: if a.is_zero: z += 1 elif a.is_zero is False: nz.append(a) else: return elif a.is_imaginary: im = True elif (S.ImaginaryUnita).is_real: im_or_z = True else: return if z == len(self.args): return True if len(nz) == len(self.args): return None b = self.func(nz) if b.is_zero: if not im_or_z and not im: return True if im and not im_or_z: return False if b.is_zero is False: return False def _eval_is_odd(self): l = [f for f in self.args if not (f.is_even is True)] if not l: return False if l[0].is_odd: return self._new_rawargs(l[1:]).is_even def _eval_is_irrational(self): for t in self.args: a = t.is_irrational if a: others = list(self.args) others.remove(t) if all(x.is_rational is True for x in others): return True return None if a is None: return return False def _eval_is_positive(self): from sympy.core.exprtools import _monotonic_sign if self.is_number: return super(Add, self)._eval_is_positive() c, a = self.as_coeff_Add() if not c.is_zero: v = _monotonic_sign(a) if v is not None: s = v + c if s != self and s.is_positive and a.is_nonnegative: return True if len(self.free_symbols) == 1: v = _monotonic_sign(self) if v is not None and v != self and v.is_positive: return True pos = nonneg = nonpos = unknown_sign = False saw_INF = set() args = [a for a in self.args if not a.is_zero] if not args: return False for a in args: ispos = a.is_positive infinite = a.is_infinite if infinite: saw_INF.add(fuzzy_or((ispos, a.is_nonnegative))) if True in saw_INF and False in saw_INF: return if ispos: pos = True continue elif a.is_nonnegative: nonneg = True continue elif a.is_nonpositive: nonpos = True continue if infinite is None: return unknown_sign = True if saw_INF: if len(saw_INF) > 1: return return saw_INF.pop() elif unknown_sign: return elif not nonpos and not nonneg and pos: return True elif not nonpos and pos: return True elif not pos and not nonneg: return False def _eval_is_nonnegative(self): from sympy.core.exprtools import _monotonic_sign if not self.is_number: c, a = self.as_coeff_Add() if not c.is_zero and a.is_nonnegative: v = _monotonic_sign(a) if v is not None: s = v + c if s != self and s.is_nonnegative: return True if len(self.free_symbols) == 1: v = _monotonic_sign(self) if v is not None and v != self and v.is_nonnegative: return True def _eval_is_nonpositive(self): from sympy.core.exprtools import _monotonic_sign if not self.is_number: c, a = self.as_coeff_Add() if not c.is_zero and a.is_nonpositive: v = _monotonic_sign(a) if v is not None: s = v + c if s != self and s.is_nonpositive: return True if len(self.free_symbols) == 1: v = _monotonic_sign(self) if v is not None and v != self and v.is_nonpositive: return True def _eval_is_negative(self): from sympy.core.exprtools import _monotonic_sign if self.is_number: return super(Add, self)._eval_is_negative() c, a = self.as_coeff_Add() if not c.is_zero: v = _monotonic_sign(a) if v is not None: s = v + c if s != self and s.is_negative and a.is_nonpositive: return True if len(self.free_symbols) == 1: v = _monotonic_sign(self) if v is not None and v != self and v.is_negative: return True neg = nonpos = nonneg = unknown_sign = False saw_INF = set() args = [a for a in self.args if not a.is_zero] if not args: return False for a in args: isneg = a.is_negative infinite = a.is_infinite if infinite: saw_INF.add(fuzzy_or((isneg, a.is_nonpositive))) if True in saw_INF and False in saw_INF: return if isneg: neg = True continue elif a.is_nonpositive: nonpos = True continue elif a.is_nonnegative: nonneg = True continue if infinite is None: return unknown_sign = True if saw_INF: if len(saw_INF) > 1: return return saw_INF.pop() elif unknown_sign: return elif not nonneg and not nonpos and neg: return True elif not nonneg and neg: return True elif not neg and not nonpos: return False def _eval_subs(self, old, new): if not old.is_Add: if old is S.Infinity and -old in self.args: # foo - oo is foo + (-oo) internally return self.xreplace({-old: -new}) return None coeff_self, terms_self = self.as_coeff_Add() coeff_old, terms_old = old.as_coeff_Add() if coeff_self.is_Rational and coeff_old.is_Rational: if terms_self == terms_old: # (2 + a).subs( 3 + a, y) -> -1 + y return self.func(new, coeff_self, -coeff_old) if terms_self == -terms_old: # (2 + a).subs(-3 - a, y) -> -1 - y return self.func(-new, coeff_self, coeff_old) if coeff_self.is_Rational and coeff_old.is_Rational \ or coeff_self == coeff_old: args_old, args_self = self.func.make_args( terms_old), self.func.make_args(terms_self) if len(args_old) < len(args_self): # (a+b+c).subs(b+c,x) -> a+x self_set = set(args_self) old_set = set(args_old) if old_set < self_set: ret_set = self_set - old_set return self.func(new, coeff_self, -coeff_old, [s._subs(old, new) for s in ret_set]) args_old = self.func.make_args( -terms_old) # (a+b+c+d).subs(-b-c,x) -> a-x+d old_set = set(args_old) if old_set < self_set: ret_set = self_set - old_set return self.func(-new, coeff_self, coeff_old, [s._subs(old, new) for s in ret_set]) def removeO(self): args = [a for a in self.args if not a.is_Order] return self._new_rawargs(args) def getO(self): args = [a for a in self.args if a.is_Order] if args: return self._new_rawargs(args) @cacheit def extract_leading_order(self, symbols, point=None): """ Returns the leading term and its order. Examples ======== >>> from sympy.abc import x >>> (x + 1 + 1/x5).extract_leading_order(x) ((x(-5), O(x(-5))),) >>> (1 + x).extract_leading_order(x) ((1, O(1)),) >>> (x + x2).extract_leading_order(x) ((x, O(x)),) """ from sympy import Order lst = [] symbols = list(symbols if is_sequence(symbols) else [symbols]) if not point: point = [0]len(symbols) seq = [(f, Order(f, zip(symbols, point))) for f in self.args] for ef, of in seq: for e, o in lst: if o.contains(of) and o != of: of = None break if of is None: continue new_lst = [(ef, of)] for e, o in lst: if of.contains(o) and o != of: continue new_lst.append((e, o)) lst = new_lst return tuple(lst) def as_real_imag(self, deep=True, hints): """ returns a tuple representing a complex number Examples ======== >>> from sympy import I >>> (7 + 9I).as_real_imag() (7, 9) >>> ((1 + I)/(1 - I)).as_real_imag() (0, 1) >>> ((1 + 2I)(1 + 3I)).as_real_imag() (-5, 5) """ sargs = self.args re_part, im_part = [], [] for term in sargs: re, im = term.as_real_imag(deep=deep) re_part.append(re) im_part.append(im) return (self.func(re_part), self.func(im_part)) def _eval_as_leading_term(self, x): from sympy import expand_mul, factor_terms old = self expr = expand_mul(self) if not expr.is_Add: return expr.as_leading_term(x) infinite = [t for t in expr.args if t.is_infinite] expr = expr.func([t.as_leading_term(x) for t in expr.args]).removeO() if not expr: # simple leading term analysis gave us 0 but we have to send # back a term, so compute the leading term (via series) return old.compute_leading_term(x) elif expr is S.NaN: return old.func._from_args(infinite) elif not expr.is_Add: return expr else: plain = expr.func([s for s, _ in expr.extract_leading_order(x)]) rv = factor_terms(plain, fraction=False) rv_simplify = rv.simplify() # if it simplifies to an x-free expression, return that; # tests don't fail if we don't but it seems nicer to do this if x not in rv_simplify.free_symbols: if rv_simplify.is_zero and plain.is_zero is not True: return (expr - plain)._eval_as_leading_term(x) return rv_simplify return rv def _eval_adjoint(self): return self.func([t.adjoint() for t in self.args]) def _eval_conjugate(self): return self.func([t.conjugate() for t in self.args]) def _eval_transpose(self): return self.func([t.transpose() for t in self.args]) def __neg__(self): return self(-1) def _sage_(self): s = 0 for x in self.args: s += x._sage_() return s def primitive(self): """ Return ``(R, self/R)`` where ``R``` is the Rational GCD of ``self```. ``R`` is collected only from the leading coefficient of each term. Examples ======== >>> from sympy.abc import x, y >>> (2x + 4y).primitive() (2, x + 2y) >>> (2x/3 + 4y/9).primitive() (2/9, 3x + 2y) >>> (2x/3 + 4.2y).primitive() (1/3, 2x + 12.6y) No subprocessing of term factors is performed: >>> ((2 + 2x)x + 2).primitive() (1, x(2x + 2) + 2) Recursive processing can be done with the ``as_content_primitive()`` method: >>> ((2 + 2x)x + 2).as_content_primitive() (2, x(x + 1) + 1) See also: primitive() function in polytools.py """ terms = [] inf = False for a in self.args: c, m = a.as_coeff_Mul() if not c.is_Rational: c = S.One m = a inf = inf or m is S.ComplexInfinity terms.append((c.p, c.q, m)) if not inf: ngcd = reduce(igcd, [t[0] for t in terms], 0) dlcm = reduce(ilcm, [t[1] for t in terms], 1) else: ngcd = reduce(igcd, [t[0] for t in terms if t[1]], 0) dlcm = reduce(ilcm, [t[1] for t in terms if t[1]], 1) if ngcd == dlcm == 1: return S.One, self if not inf: for i, (p, q, term) in enumerate(terms): terms[i] = _keep_coeff(Rational((p//ngcd)(dlcm//q)), term) else: for i, (p, q, term) in enumerate(terms): if q: terms[i] = _keep_coeff(Rational((p//ngcd)(dlcm//q)), term) else: terms[i] = _keep_coeff(Rational(p, q), term) # we don't need a complete re-flattening since no new terms will join # so we just use the same sort as is used in Add.flatten. When the # coefficient changes, the ordering of terms may change, e.g. # (3x, 6y) -> (2y, x) # # We do need to make sure that term[0] stays in position 0, however. # if terms[0].is_Number or terms[0] is S.ComplexInfinity: c = terms.pop(0) else: c = None _addsort(terms) if c: terms.insert(0, c) return Rational(ngcd, dlcm), self._new_rawargs(terms) def as_content_primitive(self, radical=False, clear=True): """Return the tuple (R, self/R) where R is the positive Rational extracted from self. If radical is True (default is False) then common radicals will be removed and included as a factor of the primitive expression. Examples ======== >>> from sympy import sqrt >>> (3 + 3sqrt(2)).as_content_primitive() (3, 1 + sqrt(2)) Radical content can also be factored out of the primitive: >>> (2sqrt(2) + 4sqrt(10)).as_content_primitive(radical=True) (2, sqrt(2)(1 + 2sqrt(5))) See docstring of Expr.as_content_primitive for more examples. """ con, prim = self.func([_keep_coeff(a.as_content_primitive( radical=radical, clear=clear)) for a in self.args]).primitive() if not clear and not con.is_Integer and prim.is_Add: con, d = con.as_numer_denom() _p = prim/d if any(a.as_coeff_Mul()[0].is_Integer for a in _p.args): prim = _p else: con /= d if radical and prim.is_Add: # look for common radicals that can be removed args = prim.args rads = [] common_q = None for m in args: term_rads = defaultdict(list) for ai in Mul.make_args(m): if ai.is_Pow: b, e = ai.as_base_exp() if e.is_Rational and b.is_Integer: term_rads[e.q].append(abs(int(b))e.p) if not term_rads: break if common_q is None: common_q = set(term_rads.keys()) else: common_q = common_q & set(term_rads.keys()) if not common_q: break rads.append(term_rads) else: # process rads # keep only those in common_q for r in rads: for q in list(r.keys()): if q not in common_q: r.pop(q) for q in r: r[q] = prod(r[q]) # find the gcd of bases for each q G = [] for q in common_q: g = reduce(igcd, [r[q] for r in rads], 0) if g != 1: G.append(gRational(1, q)) if G: G = Mul(G) args = [ai/G for ai in args] prim = Gprim.func(args) return con, prim @property def _sorted_args(self): from sympy.core.compatibility import default_sort_key return tuple(sorted(self.args, key=default_sort_key)) def _eval_difference_delta(self, n, step): from sympy.series.limitseq import difference_delta as dd return self.func([dd(a, n, step) for a in self.args]) @property def _mpc_(self): """ Convert self to an mpmath mpc if possible """ from sympy.core.numbers import I, Float re_part, rest = self.as_coeff_Add() im_part, imag_unit = rest.as_coeff_Mul() if not imag_unit == I: # ValueError may seem more reasonable but since it's a @property, # we need to use AttributeError to keep from confusing things like # hasattr. raise AttributeError("Cannot convert Add to mpc. Must be of the form Number + Number*I") return (Float(re_part)._mpf_, Float(im_part)._mpf_) from .mul import Mul, _keep_coeff, prod from sympy.core.numbers import Rational
349d0dedff271cc6c7a1c2bffc2fe715eec4f766ac5481eeaaad290b8c275cdd	from __future__ import print_function, division from .sympify import sympify, _sympify, SympifyError from .basic import Basic, Atom from .singleton import S from .evalf import EvalfMixin, pure_complex from .decorators import _sympifyit, call_highest_priority from .cache import cacheit from .compatibility import reduce, as_int, default_sort_key, range, Iterable from mpmath.libmp import mpf_log, prec_to_dps from collections import defaultdict class Expr(Basic, EvalfMixin): """ Base class for algebraic expressions. Everything that requires arithmetic operations to be defined should subclass this class, instead of Basic (which should be used only for argument storage and expression manipulation, i.e. pattern matching, substitutions, etc). See Also ======== sympy.core.basic.Basic """ __slots__ = [] is_scalar = True # self derivative is 1 @property def _diff_wrt(self): """Return True if one can differentiate with respect to this object, else False. Subclasses such as Symbol, Function and Derivative return True to enable derivatives wrt them. The implementation in Derivative separates the Symbol and non-Symbol (_diff_wrt=True) variables and temporarily converts the non-Symbols into Symbols when performing the differentiation. By default, any object deriving from Expr will behave like a scalar with self.diff(self) == 1. If this is not desired then the object must also set `is_scalar = False` or else define an _eval_derivative routine. Note, see the docstring of Derivative for how this should work mathematically. In particular, note that expr.subs(yourclass, Symbol) should be well-defined on a structural level, or this will lead to inconsistent results. Examples ======== >>> from sympy import Expr >>> e = Expr() >>> e._diff_wrt False >>> class MyScalar(Expr): ... _diff_wrt = True ... >>> MyScalar().diff(MyScalar()) 1 >>> class MySymbol(Expr): ... _diff_wrt = True ... is_scalar = False ... >>> MySymbol().diff(MySymbol()) Derivative(MySymbol(), MySymbol()) """ return False @cacheit def sort_key(self, order=None): coeff, expr = self.as_coeff_Mul() if expr.is_Pow: expr, exp = expr.args else: expr, exp = expr, S.One if expr.is_Dummy: args = (expr.sort_key(),) elif expr.is_Atom: args = (str(expr),) else: if expr.is_Add: args = expr.as_ordered_terms(order=order) elif expr.is_Mul: args = expr.as_ordered_factors(order=order) else: args = expr.args args = tuple( [ default_sort_key(arg, order=order) for arg in args ]) args = (len(args), tuple(args)) exp = exp.sort_key(order=order) return expr.class_key(), args, exp, coeff # *************** # * Arithmetics * # ************* # Expr and its sublcasses use _op_priority to determine which object # passed to a binary special method (__mul__, etc.) will handle the # operation. In general, the 'call_highest_priority' decorator will choose # the object with the highest _op_priority to handle the call. # Custom subclasses that want to define their own binary special methods # should set an _op_priority value that is higher than the default. # # NOTE*: # This is a temporary fix, and will eventually be replaced with # something better and more powerful. See issue 5510. _op_priority = 10.0 def __pos__(self): return self def __neg__(self): return Mul(S.NegativeOne, self) def __abs__(self): from sympy import Abs return Abs(self) @_sympifyit('other', NotImplemented) @call_highest_priority('__radd__') def __add__(self, other): return Add(self, other) @_sympifyit('other', NotImplemented) @call_highest_priority('__add__') def __radd__(self, other): return Add(other, self) @_sympifyit('other', NotImplemented) @call_highest_priority('__rsub__') def __sub__(self, other): return Add(self, -other) @_sympifyit('other', NotImplemented) @call_highest_priority('__sub__') def __rsub__(self, other): return Add(other, -self) @_sympifyit('other', NotImplemented) @call_highest_priority('__rmul__') def __mul__(self, other): return Mul(self, other) @_sympifyit('other', NotImplemented) @call_highest_priority('__mul__') def __rmul__(self, other): return Mul(other, self) @_sympifyit('other', NotImplemented) @call_highest_priority('__rpow__') def _pow(self, other): return Pow(self, other) def __pow__(self, other, mod=None): if mod is None: return self._pow(other) try: _self, other, mod = as_int(self), as_int(other), as_int(mod) if other >= 0: return pow(_self, other, mod) else: from sympy.core.numbers import mod_inverse return mod_inverse(pow(_self, -other, mod), mod) except ValueError: power = self._pow(other) try: return power%mod except TypeError: return NotImplemented @_sympifyit('other', NotImplemented) @call_highest_priority('__pow__') def __rpow__(self, other): return Pow(other, self) @_sympifyit('other', NotImplemented) @call_highest_priority('__rdiv__') def __div__(self, other): return Mul(self, Pow(other, S.NegativeOne)) @_sympifyit('other', NotImplemented) @call_highest_priority('__div__') def __rdiv__(self, other): return Mul(other, Pow(self, S.NegativeOne)) __truediv__ = __div__ __rtruediv__ = __rdiv__ @_sympifyit('other', NotImplemented) @call_highest_priority('__rmod__') def __mod__(self, other): return Mod(self, other) @_sympifyit('other', NotImplemented) @call_highest_priority('__mod__') def __rmod__(self, other): return Mod(other, self) @_sympifyit('other', NotImplemented) @call_highest_priority('__rfloordiv__') def __floordiv__(self, other): from sympy.functions.elementary.integers import floor return floor(self / other) @_sympifyit('other', NotImplemented) @call_highest_priority('__floordiv__') def __rfloordiv__(self, other): from sympy.functions.elementary.integers import floor return floor(other / self) @_sympifyit('other', NotImplemented) @call_highest_priority('__rdivmod__') def __divmod__(self, other): from sympy.functions.elementary.integers import floor return floor(self / other), Mod(self, other) @_sympifyit('other', NotImplemented) @call_highest_priority('__divmod__') def __rdivmod__(self, other): from sympy.functions.elementary.integers import floor return floor(other / self), Mod(other, self) def __int__(self): # Although we only need to round to the units position, we'll # get one more digit so the extra testing below can be avoided # unless the rounded value rounded to an integer, e.g. if an # expression were equal to 1.9 and we rounded to the unit position # we would get a 2 and would not know if this rounded up or not # without doing a test (as done below). But if we keep an extra # digit we know that 1.9 is not the same as 1 and there is no # need for further testing: our int value is correct. If the value # were 1.99, however, this would round to 2.0 and our int value is # off by one. So...if our round value is the same as the int value # (regardless of how much extra work we do to calculate extra decimal # places) we need to test whether we are off by one. from sympy import Dummy if not self.is_number: raise TypeError("can't convert symbols to int") r = self.round(2) if not r.is_Number: raise TypeError("can't convert complex to int") if r in (S.NaN, S.Infinity, S.NegativeInfinity): raise TypeError("can't convert %s to int" % r) i = int(r) if not i: return 0 # off-by-one check if i == r and not (self - i).equals(0): isign = 1 if i > 0 else -1 x = Dummy() # in the following (self - i).evalf(2) will not always work while # (self - r).evalf(2) and the use of subs does; if the test that # was added when this comment was added passes, it might be safe # to simply use sign to compute this rather than doing this by hand: diff_sign = 1 if (self - x).evalf(2, subs={x: i}) > 0 else -1 if diff_sign != isign: i -= isign return i __long__ = __int__ def __float__(self): # Don't bother testing if it's a number; if it's not this is going # to fail, and if it is we still need to check that it evalf'ed to # a number. result = self.evalf() if result.is_Number: return float(result) if result.is_number and result.as_real_imag()[1]: raise TypeError("can't convert complex to float") raise TypeError("can't convert expression to float") def __complex__(self): result = self.evalf() re, im = result.as_real_imag() return complex(float(re), float(im)) def __ge__(self, other): from sympy import GreaterThan try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s >= %s" % (self, other)) for me in (self, other): if me.is_complex and me.is_real is False: raise TypeError("Invalid comparison of complex %s" % me) if me is S.NaN: raise TypeError("Invalid NaN comparison") n2 = _n2(self, other) if n2 is not None: return _sympify(n2 >= 0) if self.is_real or other.is_real: dif = self - other if dif.is_nonnegative is not None and \ dif.is_nonnegative is not dif.is_negative: return sympify(dif.is_nonnegative) return GreaterThan(self, other, evaluate=False) def __le__(self, other): from sympy import LessThan try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s <= %s" % (self, other)) for me in (self, other): if me.is_complex and me.is_real is False: raise TypeError("Invalid comparison of complex %s" % me) if me is S.NaN: raise TypeError("Invalid NaN comparison") n2 = _n2(self, other) if n2 is not None: return _sympify(n2 <= 0) if self.is_real or other.is_real: dif = self - other if dif.is_nonpositive is not None and \ dif.is_nonpositive is not dif.is_positive: return sympify(dif.is_nonpositive) return LessThan(self, other, evaluate=False) def __gt__(self, other): from sympy import StrictGreaterThan try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s > %s" % (self, other)) for me in (self, other): if me.is_complex and me.is_real is False: raise TypeError("Invalid comparison of complex %s" % me) if me is S.NaN: raise TypeError("Invalid NaN comparison") n2 = _n2(self, other) if n2 is not None: return _sympify(n2 > 0) if self.is_real or other.is_real: dif = self - other if dif.is_positive is not None and \ dif.is_positive is not dif.is_nonpositive: return sympify(dif.is_positive) return StrictGreaterThan(self, other, evaluate=False) def __lt__(self, other): from sympy import StrictLessThan try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s < %s" % (self, other)) for me in (self, other): if me.is_complex and me.is_real is False: raise TypeError("Invalid comparison of complex %s" % me) if me is S.NaN: raise TypeError("Invalid NaN comparison") n2 = _n2(self, other) if n2 is not None: return _sympify(n2 < 0) if self.is_real or other.is_real: dif = self - other if dif.is_negative is not None and \ dif.is_negative is not dif.is_nonnegative: return sympify(dif.is_negative) return StrictLessThan(self, other, evaluate=False) def __trunc__(self): if not self.is_number: raise TypeError("can't truncate symbols and expressions") else: return Integer(self) @staticmethod def _from_mpmath(x, prec): from sympy import Float if hasattr(x, "_mpf_"): return Float._new(x._mpf_, prec) elif hasattr(x, "_mpc_"): re, im = x._mpc_ re = Float._new(re, prec) im = Float._new(im, prec)S.ImaginaryUnit return re + im else: raise TypeError("expected mpmath number (mpf or mpc)") @property def is_number(self): """Returns True if ``self`` has no free symbols and no undefined functions (AppliedUndef, to be precise). It will be faster than ``if not self.free_symbols``, however, since ``is_number`` will fail as soon as it hits a free symbol or undefined function. Examples ======== >>> from sympy import log, Integral, cos, sin, pi >>> from sympy.core.function import Function >>> from sympy.abc import x >>> f = Function('f') >>> x.is_number False >>> f(1).is_number False >>> (2x).is_number False >>> (2 + Integral(2, x)).is_number False >>> (2 + Integral(2, (x, 1, 2))).is_number True Not all numbers are Numbers in the SymPy sense: >>> pi.is_number, pi.is_Number (True, False) If something is a number it should evaluate to a number with real and imaginary parts that are Numbers; the result may not be comparable, however, since the real and/or imaginary part of the result may not have precision. >>> cos(1).is_number and cos(1).is_comparable True >>> z = cos(1)2 + sin(1)2 - 1 >>> z.is_number True >>> z.is_comparable False See Also ======== sympy.core.basic.is_comparable """ return all(obj.is_number for obj in self.args) def _random(self, n=None, re_min=-1, im_min=-1, re_max=1, im_max=1): """Return self evaluated, if possible, replacing free symbols with random complex values, if necessary. The random complex value for each free symbol is generated by the random_complex_number routine giving real and imaginary parts in the range given by the re_min, re_max, im_min, and im_max values. The returned value is evaluated to a precision of n (if given) else the maximum of 15 and the precision needed to get more than 1 digit of precision. If the expression could not be evaluated to a number, or could not be evaluated to more than 1 digit of precision, then None is returned. Examples ======== >>> from sympy import sqrt >>> from sympy.abc import x, y >>> x._random() # doctest: +SKIP 0.0392918155679172 + 0.916050214307199I >>> x._random(2) # doctest: +SKIP -0.77 - 0.87I >>> (x + y/2)._random(2) # doctest: +SKIP -0.57 + 0.16I >>> sqrt(2)._random(2) 1.4 See Also ======== sympy.utilities.randtest.random_complex_number """ free = self.free_symbols prec = 1 if free: from sympy.utilities.randtest import random_complex_number a, c, b, d = re_min, re_max, im_min, im_max reps = dict(list(zip(free, [random_complex_number(a, b, c, d, rational=True) for zi in free]))) try: nmag = abs(self.evalf(2, subs=reps)) except (ValueError, TypeError): # if an out of range value resulted in evalf problems # then return None -- XXX is there a way to know how to # select a good random number for a given expression? # e.g. when calculating n! negative values for n should not # be used return None else: reps = {} nmag = abs(self.evalf(2)) if not hasattr(nmag, '_prec'): # e.g. exp_polar(2Ipi) doesn't evaluate but is_number is True return None if nmag._prec == 1: # increase the precision up to the default maximum # precision to see if we can get any significance from mpmath.libmp.libintmath import giant_steps from sympy.core.evalf import DEFAULT_MAXPREC as target # evaluate for prec in giant_steps(2, target): nmag = abs(self.evalf(prec, subs=reps)) if nmag._prec != 1: break if nmag._prec != 1: if n is None: n = max(prec, 15) return self.evalf(n, subs=reps) # never got any significance return None def is_constant(self, wrt, flags): """Return True if self is constant, False if not, or None if the constancy could not be determined conclusively. If an expression has no free symbols then it is a constant. If there are free symbols it is possible that the expression is a constant, perhaps (but not necessarily) zero. To test such expressions, two strategies are tried: 1) numerical evaluation at two random points. If two such evaluations give two different values and the values have a precision greater than 1 then self is not constant. If the evaluations agree or could not be obtained with any precision, no decision is made. The numerical testing is done only if ``wrt`` is different than the free symbols. 2) differentiation with respect to variables in 'wrt' (or all free symbols if omitted) to see if the expression is constant or not. This will not always lead to an expression that is zero even though an expression is constant (see added test in test_expr.py). If all derivatives are zero then self is constant with respect to the given symbols. If neither evaluation nor differentiation can prove the expression is constant, None is returned unless two numerical values happened to be the same and the flag ``failing_number`` is True -- in that case the numerical value will be returned. If flag simplify=False is passed, self will not be simplified; the default is True since self should be simplified before testing. Examples ======== >>> from sympy import cos, sin, Sum, S, pi >>> from sympy.abc import a, n, x, y >>> x.is_constant() False >>> S(2).is_constant() True >>> Sum(x, (x, 1, 10)).is_constant() True >>> Sum(x, (x, 1, n)).is_constant() False >>> Sum(x, (x, 1, n)).is_constant(y) True >>> Sum(x, (x, 1, n)).is_constant(n) False >>> Sum(x, (x, 1, n)).is_constant(x) True >>> eq = acos(x)*2 + asin(x)2 - a >>> eq.is_constant() True >>> eq.subs({x: pi, a: 2}) == eq.subs({x: pi, a: 3}) == 0 True >>> (0x).is_constant() False >>> x.is_constant() False >>> (xx).is_constant() False >>> one = cos(x)2 + sin(x)2 >>> one.is_constant() True >>> ((one - 1)(x + 1)).is_constant() in (True, False) # could be 0 or 1 True """ simplify = flags.get('simplify', True) if self.is_number: return True free = self.free_symbols if not free: return True # assume f(1) is some constant # if we are only interested in some symbols and they are not in the # free symbols then this expression is constant wrt those symbols wrt = set(wrt) if wrt and not wrt & free: return True wrt = wrt or free # simplify unless this has already been done expr = self if simplify: expr = expr.simplify() # is_zero should be a quick assumptions check; it can be wrong for # numbers (see test_is_not_constant test), giving False when it # shouldn't, but hopefully it will never give True unless it is sure. if expr.is_zero: return True # try numerical evaluation to see if we get two different values failing_number = None if wrt == free: # try 0 (for a) and 1 (for b) try: a = expr.subs(list(zip(free, [0]len(free))), simultaneous=True) if a is S.NaN: # evaluation may succeed when substitution fails a = expr._random(None, 0, 0, 0, 0) except ZeroDivisionError: a = None if a is not None and a is not S.NaN: try: b = expr.subs(list(zip(free, [1]len(free))), simultaneous=True) if b is S.NaN: # evaluation may succeed when substitution fails b = expr._random(None, 1, 0, 1, 0) except ZeroDivisionError: b = None if b is not None and b is not S.NaN and b.equals(a) is False: return False # try random real b = expr._random(None, -1, 0, 1, 0) if b is not None and b is not S.NaN and b.equals(a) is False: return False # try random complex b = expr._random() if b is not None and b is not S.NaN: if b.equals(a) is False: return False failing_number = a if a.is_number else b # now we will test each wrt symbol (or all free symbols) to see if the # expression depends on them or not using differentiation. This is # not sufficient for all expressions, however, so we don't return # False if we get a derivative other than 0 with free symbols. for w in wrt: deriv = expr.diff(w) if simplify: deriv = deriv.simplify() if deriv != 0: if not (pure_complex(deriv, or_real=True)): if flags.get('failing_number', False): return failing_number elif deriv.free_symbols: # dead line provided _random returns None in such cases return None return False return True def equals(self, other, failing_expression=False): """Return True if self == other, False if it doesn't, or None. If failing_expression is True then the expression which did not simplify to a 0 will be returned instead of None. If ``self`` is a Number (or complex number) that is not zero, then the result is False. If ``self`` is a number and has not evaluated to zero, evalf will be used to test whether the expression evaluates to zero. If it does so and the result has significance (i.e. the precision is either -1, for a Rational result, or is greater than 1) then the evalf value will be used to return True or False. """ from sympy.simplify.simplify import nsimplify, simplify from sympy.solvers.solveset import solveset from sympy.polys.polyerrors import NotAlgebraic from sympy.polys.numberfields import minimal_polynomial other = sympify(other) if self == other: return True # they aren't the same so see if we can make the difference 0; # don't worry about doing simplification steps one at a time # because if the expression ever goes to 0 then the subsequent # simplification steps that are done will be very fast. diff = factor_terms(simplify(self - other), radical=True) if not diff: return True if not diff.has(Add, Mod): # if there is no expanding to be done after simplifying # then this can't be a zero return False constant = diff.is_constant(simplify=False, failing_number=True) if constant is False: return False if constant is None and (diff.free_symbols or not diff.is_number): # e.g. unless the right simplification is done, a symbolic # zero is possible (see expression of issue 6829: without # simplification constant will be None). return if constant is True: ndiff = diff._random() if ndiff: return False # sometimes we can use a simplified result to give a clue as to # what the expression should be; if the expression is not zero # then we should have been able to compute that and so now # we can just consider the cases where the approximation appears # to be zero -- we try to prove it via minimal_polynomial. if diff.is_number: approx = diff.nsimplify() if not approx: # try to prove via self-consistency surds = [s for s in diff.atoms(Pow) if s.args[0].is_Integer] # it seems to work better to try big ones first surds.sort(key=lambda x: -x.args[0]) for s in surds: try: # simplify is False here -- this expression has already # been identified as being hard to identify as zero; # we will handle the checking ourselves using nsimplify # to see if we are in the right ballpark or not and if so # then the simplification will be attempted. if s.is_Symbol: sol = list(solveset(diff, s)) else: sol = [s] if sol: if s in sol: return True if s.is_real: if any(nsimplify(si, [s]) == s and simplify(si) == s for si in sol): return True except NotImplementedError: pass # try to prove with minimal_polynomial but know when # not to use this or else it can take a long time. e.g. issue 8354 if True: # change True to condition that assures non-hang try: mp = minimal_polynomial(diff) if mp.is_Symbol: return True return False except (NotAlgebraic, NotImplementedError): pass # diff has not simplified to zero; constant is either None, True # or the number with significance (prec != 1) that was randomly # calculated twice as the same value. if constant not in (True, None) and constant != 0: return False if failing_expression: return diff return None def _eval_is_positive(self): from sympy.polys.numberfields import minimal_polynomial from sympy.polys.polyerrors import NotAlgebraic if self.is_number: if self.is_real is False: return False try: # check to see that we can get a value n2 = self._eval_evalf(2) if n2 is None: raise AttributeError if n2._prec == 1: # no significance raise AttributeError if n2 == S.NaN: raise AttributeError except (AttributeError, ValueError): return None n, i = self.evalf(2).as_real_imag() if not i.is_Number or not n.is_Number: return False if n._prec != 1 and i._prec != 1: return bool(not i and n > 0) elif n._prec == 1 and (not i or i._prec == 1) and \ self.is_algebraic and not self.has(Function): try: if minimal_polynomial(self).is_Symbol: return False except (NotAlgebraic, NotImplementedError): pass def _eval_is_negative(self): from sympy.polys.numberfields import minimal_polynomial from sympy.polys.polyerrors import NotAlgebraic if self.is_number: if self.is_real is False: return False try: # check to see that we can get a value n2 = self._eval_evalf(2) if n2 is None: raise AttributeError if n2._prec == 1: # no significance raise AttributeError if n2 == S.NaN: raise AttributeError except (AttributeError, ValueError): return None n, i = self.evalf(2).as_real_imag() if not i.is_Number or not n.is_Number: return False if n._prec != 1 and i._prec != 1: return bool(not i and n < 0) elif n._prec == 1 and (not i or i._prec == 1) and \ self.is_algebraic and not self.has(Function): try: if minimal_polynomial(self).is_Symbol: return False except (NotAlgebraic, NotImplementedError): pass def _eval_interval(self, x, a, b): """ Returns evaluation over an interval. For most functions this is: self.subs(x, b) - self.subs(x, a), possibly using limit() if NaN is returned from subs, or if singularities are found between a and b. If b or a is None, it only evaluates -self.subs(x, a) or self.subs(b, x), respectively. """ from sympy.series import limit, Limit from sympy.solvers.solveset import solveset from sympy.sets.sets import Interval from sympy.functions.elementary.exponential import log from sympy.calculus.util import AccumBounds if (a is None and b is None): raise ValueError('Both interval ends cannot be None.') if a == b: return 0 if a is None: A = 0 else: A = self.subs(x, a) if A.has(S.NaN, S.Infinity, S.NegativeInfinity, S.ComplexInfinity, AccumBounds): if (a < b) != False: A = limit(self, x, a,"+") else: A = limit(self, x, a,"-") if A is S.NaN: return A if isinstance(A, Limit): raise NotImplementedError("Could not compute limit") if b is None: B = 0 else: B = self.subs(x, b) if B.has(S.NaN, S.Infinity, S.NegativeInfinity, S.ComplexInfinity, AccumBounds): if (a < b) != False: B = limit(self, x, b,"-") else: B = limit(self, x, b,"+") if isinstance(B, Limit): raise NotImplementedError("Could not compute limit") if (a and b) is None: return B - A value = B - A if a.is_comparable and b.is_comparable: if a < b: domain = Interval(a, b) else: domain = Interval(b, a) # check the singularities of self within the interval # if singularities is a ConditionSet (not iterable), catch the exception and pass singularities = solveset(self.cancel().as_numer_denom()[1], x, domain=domain) for logterm in self.atoms(log): singularities = singularities \| solveset(logterm.args[0], x, domain=domain) try: for s in singularities: if value is S.NaN: # no need to keep adding, it will stay NaN break if not s.is_comparable: continue if (a < s) == (s < b) == True: value += -limit(self, x, s, "+") + limit(self, x, s, "-") elif (b < s) == (s < a) == True: value += limit(self, x, s, "+") - limit(self, x, s, "-") except TypeError: pass return value def _eval_power(self, other): # subclass to compute selfother for cases when # other is not NaN, 0, or 1 return None def _eval_conjugate(self): if self.is_real: return self elif self.is_imaginary: return -self def conjugate(self): from sympy.functions.elementary.complexes import conjugate as c return c(self) def _eval_transpose(self): from sympy.functions.elementary.complexes import conjugate if self.is_complex: return self elif self.is_hermitian: return conjugate(self) elif self.is_antihermitian: return -conjugate(self) def transpose(self): from sympy.functions.elementary.complexes import transpose return transpose(self) def _eval_adjoint(self): from sympy.functions.elementary.complexes import conjugate, transpose if self.is_hermitian: return self elif self.is_antihermitian: return -self obj = self._eval_conjugate() if obj is not None: return transpose(obj) obj = self._eval_transpose() if obj is not None: return conjugate(obj) def adjoint(self): from sympy.functions.elementary.complexes import adjoint return adjoint(self) @classmethod def _parse_order(cls, order): """Parse and configure the ordering of terms. """ from sympy.polys.orderings import monomial_key try: reverse = order.startswith('rev-') except AttributeError: reverse = False else: if reverse: order = order[4:] monom_key = monomial_key(order) def neg(monom): result = [] for m in monom: if isinstance(m, tuple): result.append(neg(m)) else: result.append(-m) return tuple(result) def key(term): _, ((re, im), monom, ncpart) = term monom = neg(monom_key(monom)) ncpart = tuple([e.sort_key(order=order) for e in ncpart]) coeff = ((bool(im), im), (re, im)) return monom, ncpart, coeff return key, reverse def as_ordered_factors(self, order=None): """Return list of ordered factors (if Mul) else [self].""" return [self] def as_ordered_terms(self, order=None, data=False): """ Transform an expression to an ordered list of terms. Examples ======== >>> from sympy import sin, cos >>> from sympy.abc import x >>> (sin(x)2cos(x) + sin(x)2 + 1).as_ordered_terms() [sin(x)2cos(x), sin(x)*2, 1] """ key, reverse = self._parse_order(order) terms, gens = self.as_terms() if not any(term.is_Order for term, _ in terms): ordered = sorted(terms, key=key, reverse=reverse) else: _terms, _order = [], [] for term, repr in terms: if not term.is_Order: _terms.append((term, repr)) else: _order.append((term, repr)) ordered = sorted(_terms, key=key, reverse=True) \ + sorted(_order, key=key, reverse=True) if data: return ordered, gens else: return [term for term, _ in ordered] def as_terms(self): """Transform an expression to a list of terms. """ from .add import Add from .mul import Mul from .exprtools import decompose_power gens, terms = set([]), [] for term in Add.make_args(self): coeff, _term = term.as_coeff_Mul() coeff = complex(coeff) cpart, ncpart = {}, [] if _term is not S.One: for factor in Mul.make_args(_term): if factor.is_number: try: coeff = complex(factor) except (TypeError, ValueError): pass else: continue if factor.is_commutative: base, exp = decompose_power(factor) cpart[base] = exp gens.add(base) else: ncpart.append(factor) coeff = coeff.real, coeff.imag ncpart = tuple(ncpart) terms.append((term, (coeff, cpart, ncpart))) gens = sorted(gens, key=default_sort_key) k, indices = len(gens), {} for i, g in enumerate(gens): indices[g] = i result = [] for term, (coeff, cpart, ncpart) in terms: monom = [0]k for base, exp in cpart.items(): monom[indices[base]] = exp result.append((term, (coeff, tuple(monom), ncpart))) return result, gens def removeO(self): """Removes the additive O(..) symbol if there is one""" return self def getO(self): """Returns the additive O(..) symbol if there is one, else None.""" return None def getn(self): """ Returns the order of the expression. The order is determined either from the O(...) term. If there is no O(...) term, it returns None. Examples ======== >>> from sympy import O >>> from sympy.abc import x >>> (1 + x + O(x2)).getn() 2 >>> (1 + x).getn() """ from sympy import Dummy, Symbol o = self.getO() if o is None: return None elif o.is_Order: o = o.expr if o is S.One: return S.Zero if o.is_Symbol: return S.One if o.is_Pow: return o.args[1] if o.is_Mul: # xnlog(x)n or xn/log(x)*n for oi in o.args: if oi.is_Symbol: return S.One if oi.is_Pow: syms = oi.atoms(Symbol) if len(syms) == 1: x = syms.pop() oi = oi.subs(x, Dummy('x', positive=True)) if oi.base.is_Symbol and oi.exp.is_Rational: return abs(oi.exp) raise NotImplementedError('not sure of order of %s' % o) def count_ops(self, visual=None): """wrapper for count_ops that returns the operation count.""" from .function import count_ops return count_ops(self, visual) def args_cnc(self, cset=False, warn=True, split_1=True): """Return [commutative factors, non-commutative factors] of self. self is treated as a Mul and the ordering of the factors is maintained. If ``cset`` is True the commutative factors will be returned in a set. If there were repeated factors (as may happen with an unevaluated Mul) then an error will be raised unless it is explicitly suppressed by setting ``warn`` to False. Note: -1 is always separated from a Number unless split_1 is False. >>> from sympy import symbols, oo >>> A, B = symbols('A B', commutative=0) >>> x, y = symbols('x y') >>> (-2xy).args_cnc() [[-1, 2, x, y], []] >>> (-2.5x).args_cnc() [[-1, 2.5, x], []] >>> (-2xABy).args_cnc() [[-1, 2, x, y], [A, B]] >>> (-2xABy).args_cnc(split_1=False) [[-2, x, y], [A, B]] >>> (-2xy).args_cnc(cset=True) [{-1, 2, x, y}, []] The arg is always treated as a Mul: >>> (-2 + x + A).args_cnc() [[], [x - 2 + A]] >>> (-oo).args_cnc() # -oo is a singleton [[-1, oo], []] """ if self.is_Mul: args = list(self.args) else: args = [self] for i, mi in enumerate(args): if not mi.is_commutative: c = args[:i] nc = args[i:] break else: c = args nc = [] if c and split_1 and ( c[0].is_Number and c[0].is_negative and c[0] is not S.NegativeOne): c[:1] = [S.NegativeOne, -c[0]] if cset: clen = len(c) c = set(c) if clen and warn and len(c) != clen: raise ValueError('repeated commutative arguments: %s' % [ci for ci in c if list(self.args).count(ci) > 1]) return [c, nc] def coeff(self, x, n=1, right=False): """ Returns the coefficient from the term(s) containing ``x*n``. If ``n`` is zero then all terms independent of ``x`` will be returned. When ``x`` is noncommutative, the coefficient to the left (default) or right of ``x`` can be returned. The keyword 'right' is ignored when ``x`` is commutative. See Also ======== as_coefficient: separate the expression into a coefficient and factor as_coeff_Add: separate the additive constant from an expression as_coeff_Mul: separate the multiplicative constant from an expression as_independent: separate x-dependent terms/factors from others sympy.polys.polytools.coeff_monomial: efficiently find the single coefficient of a monomial in Poly sympy.polys.polytools.nth: like coeff_monomial but powers of monomial terms are used Examples ======== >>> from sympy import symbols >>> from sympy.abc import x, y, z You can select terms that have an explicit negative in front of them: >>> (-x + 2y).coeff(-1) x >>> (x - 2y).coeff(-1) 2y You can select terms with no Rational coefficient: >>> (x + 2y).coeff(1) x >>> (3 + 2x + 4x2).coeff(1) 0 You can select terms independent of x by making n=0; in this case expr.as_independent(x)[0] is returned (and 0 will be returned instead of None): >>> (3 + 2x + 4x2).coeff(x, 0) 3 >>> eq = ((x + 1)3).expand() + 1 >>> eq x3 + 3x*2 + 3x + 2 >>> [eq.coeff(x, i) for i in reversed(range(4))] [1, 3, 3, 2] >>> eq -= 2 >>> [eq.coeff(x, i) for i in reversed(range(4))] [1, 3, 3, 0] You can select terms that have a numerical term in front of them: >>> (-x - 2y).coeff(2) -y >>> from sympy import sqrt >>> (x + sqrt(2)x).coeff(sqrt(2)) x The matching is exact: >>> (3 + 2x + 4x*2).coeff(x) 2 >>> (3 + 2x + 4x2).coeff(x2) 4 >>> (3 + 2x + 4x2).coeff(x3) 0 >>> (z(x + y)2).coeff((x + y)2) z >>> (z(x + y)2).coeff(x + y) 0 In addition, no factoring is done, so 1 + z(1 + y) is not obtained from the following: >>> (x + z(x + xy)).coeff(x) 1 If such factoring is desired, factor_terms can be used first: >>> from sympy import factor_terms >>> factor_terms(x + z(x + xy)).coeff(x) z(y + 1) + 1 >>> n, m, o = symbols('n m o', commutative=False) >>> n.coeff(n) 1 >>> (3n).coeff(n) 3 >>> (nm + mnm).coeff(n) # = (1 + m)nm 1 + m >>> (nm + mnm).coeff(n, right=True) # = (1 + m)nm m If there is more than one possible coefficient 0 is returned: >>> (nm + mn).coeff(n) 0 If there is only one possible coefficient, it is returned: >>> (nm + xmn).coeff(mn) x >>> (nm + xmn).coeff(mn, right=1) 1 """ x = sympify(x) if not isinstance(x, Basic): return S.Zero n = as_int(n) if not x: return S.Zero if x == self: if n == 1: return S.One return S.Zero if x is S.One: co = [a for a in Add.make_args(self) if a.as_coeff_Mul()[0] is S.One] if not co: return S.Zero return Add(co) if n == 0: if x.is_Add and self.is_Add: c = self.coeff(x, right=right) if not c: return S.Zero if not right: return self - Add([ax for a in Add.make_args(c)]) return self - Add([xa for a in Add.make_args(c)]) return self.as_independent(x, as_Add=True)[0] # continue with the full method, looking for this power of x: x = xn def incommon(l1, l2): if not l1 or not l2: return [] n = min(len(l1), len(l2)) for i in range(n): if l1[i] != l2[i]: return l1[:i] return l1[:] def find(l, sub, first=True): """ Find where list sub appears in list l. When ``first`` is True the first occurrence from the left is returned, else the last occurrence is returned. Return None if sub is not in l. >> l = range(5)2 >> find(l, [2, 3]) 2 >> find(l, [2, 3], first=0) 7 >> find(l, [2, 4]) None """ if not sub or not l or len(sub) > len(l): return None n = len(sub) if not first: l.reverse() sub.reverse() for i in range(0, len(l) - n + 1): if all(l[i + j] == sub[j] for j in range(n)): break else: i = None if not first: l.reverse() sub.reverse() if i is not None and not first: i = len(l) - (i + n) return i co = [] args = Add.make_args(self) self_c = self.is_commutative x_c = x.is_commutative if self_c and not x_c: return S.Zero if self_c: xargs = x.args_cnc(cset=True, warn=False)[0] for a in args: margs = a.args_cnc(cset=True, warn=False)[0] if len(xargs) > len(margs): continue resid = margs.difference(xargs) if len(resid) + len(xargs) == len(margs): co.append(Mul(resid)) if co == []: return S.Zero elif co: return Add(co) elif x_c: xargs = x.args_cnc(cset=True, warn=False)[0] for a in args: margs, nc = a.args_cnc(cset=True) if len(xargs) > len(margs): continue resid = margs.difference(xargs) if len(resid) + len(xargs) == len(margs): co.append(Mul((list(resid) + nc))) if co == []: return S.Zero elif co: return Add(co) else: # both nc xargs, nx = x.args_cnc(cset=True) # find the parts that pass the commutative terms for a in args: margs, nc = a.args_cnc(cset=True) if len(xargs) > len(margs): continue resid = margs.difference(xargs) if len(resid) + len(xargs) == len(margs): co.append((resid, nc)) # now check the non-comm parts if not co: return S.Zero if all(n == co[0][1] for r, n in co): ii = find(co[0][1], nx, right) if ii is not None: if not right: return Mul(Add([Mul(r) for r, c in co]), Mul(co[0][1][:ii])) else: return Mul(co[0][1][ii + len(nx):]) beg = reduce(incommon, (n[1] for n in co)) if beg: ii = find(beg, nx, right) if ii is not None: if not right: gcdc = co[0][0] for i in range(1, len(co)): gcdc = gcdc.intersection(co[i][0]) if not gcdc: break return Mul((list(gcdc) + beg[:ii])) else: m = ii + len(nx) return Add([Mul((list(r) + n[m:])) for r, n in co]) end = list(reversed( reduce(incommon, (list(reversed(n[1])) for n in co)))) if end: ii = find(end, nx, right) if ii is not None: if not right: return Add([Mul((list(r) + n[:-len(end) + ii])) for r, n in co]) else: return Mul(end[ii + len(nx):]) # look for single match hit = None for i, (r, n) in enumerate(co): ii = find(n, nx, right) if ii is not None: if not hit: hit = ii, r, n else: break else: if hit: ii, r, n = hit if not right: return Mul((list(r) + n[:ii])) else: return Mul(n[ii + len(nx):]) return S.Zero def as_expr(self, gens): """ Convert a polynomial to a SymPy expression. Examples ======== >>> from sympy import sin >>> from sympy.abc import x, y >>> f = (x2 + xy).as_poly(x, y) >>> f.as_expr() x*2 + xy >>> sin(x).as_expr() sin(x) """ return self def as_coefficient(self, expr): """ Extracts symbolic coefficient at the given expression. In other words, this functions separates 'self' into the product of 'expr' and 'expr'-free coefficient. If such separation is not possible it will return None. Examples ======== >>> from sympy import E, pi, sin, I, Poly >>> from sympy.abc import x >>> E.as_coefficient(E) 1 >>> (2E).as_coefficient(E) 2 >>> (2sin(E)E).as_coefficient(E) Two terms have E in them so a sum is returned. (If one were desiring the coefficient of the term exactly matching E then the constant from the returned expression could be selected. Or, for greater precision, a method of Poly can be used to indicate the desired term from which the coefficient is desired.) >>> (2E + xE).as_coefficient(E) x + 2 >>> _.args[0] # just want the exact match 2 >>> p = Poly(2E + xE); p Poly(xE + 2E, x, E, domain='ZZ') >>> p.coeff_monomial(E) 2 >>> p.nth(0, 1) 2 Since the following cannot be written as a product containing E as a factor, None is returned. (If the coefficient ``2x`` is desired then the ``coeff`` method should be used.) >>> (2Ex + x).as_coefficient(E) >>> (2Ex + x).coeff(E) 2x >>> (E(x + 1) + x).as_coefficient(E) >>> (2piI).as_coefficient(piI) 2 >>> (2I).as_coefficient(piI) See Also ======== coeff: return sum of terms have a given factor as_coeff_Add: separate the additive constant from an expression as_coeff_Mul: separate the multiplicative constant from an expression as_independent: separate x-dependent terms/factors from others sympy.polys.polytools.coeff_monomial: efficiently find the single coefficient of a monomial in Poly sympy.polys.polytools.nth: like coeff_monomial but powers of monomial terms are used """ r = self.extract_multiplicatively(expr) if r and not r.has(expr): return r def as_independent(self, deps, *hint): """ A mostly naive separation of a Mul or Add into arguments that are not are dependent on deps. To obtain as complete a separation of variables as possible, use a separation method first, e.g.: separatevars() to change Mul, Add and Pow (including exp) into Mul * .expand(mul=True) to change Add or Mul into Add * .expand(log=True) to change log expr into an Add The only non-naive thing that is done here is to respect noncommutative ordering of variables and to always return (0, 0) for `self` of zero regardless of hints. For nonzero `self`, the returned tuple (i, d) has the following interpretation: * i will has no variable that appears in deps * d will either have terms that contain variables that are in deps, or be equal to 0 (when self is an Add) or 1 (when self is a Mul) * if self is an Add then self = i + d * if self is a Mul then self = id otherwise (self, S.One) or (S.One, self) is returned. To force the expression to be treated as an Add, use the hint as_Add=True Examples ======== -- self is an Add >>> from sympy import sin, cos, exp >>> from sympy.abc import x, y, z >>> (x + xy).as_independent(x) (0, xy + x) >>> (x + xy).as_independent(y) (x, xy) >>> (2xsin(x) + y + x + z).as_independent(x) (y + z, 2xsin(x) + x) >>> (2xsin(x) + y + x + z).as_independent(x, y) (z, 2xsin(x) + x + y) -- self is a Mul >>> (xsin(x)cos(y)).as_independent(x) (cos(y), xsin(x)) non-commutative terms cannot always be separated out when self is a Mul >>> from sympy import symbols >>> n1, n2, n3 = symbols('n1 n2 n3', commutative=False) >>> (n1 + n1n2).as_independent(n2) (n1, n1n2) >>> (n2n1 + n1n2).as_independent(n2) (0, n1n2 + n2n1) >>> (n1n2n3).as_independent(n1) (1, n1n2n3) >>> (n1n2n3).as_independent(n2) (n1, n2n3) >>> ((x-n1)(x-y)).as_independent(x) (1, (x - y)(x - n1)) -- self is anything else: >>> (sin(x)).as_independent(x) (1, sin(x)) >>> (sin(x)).as_independent(y) (sin(x), 1) >>> exp(x+y).as_independent(x) (1, exp(x + y)) -- force self to be treated as an Add: >>> (3x).as_independent(x, as_Add=True) (0, 3x) -- force self to be treated as a Mul: >>> (3+x).as_independent(x, as_Add=False) (1, x + 3) >>> (-3+x).as_independent(x, as_Add=False) (1, x - 3) Note how the below differs from the above in making the constant on the dep term positive. >>> (y(-3+x)).as_independent(x) (y, x - 3) -- use .as_independent() for true independence testing instead of .has(). The former considers only symbols in the free symbols while the latter considers all symbols >>> from sympy import Integral >>> I = Integral(x, (x, 1, 2)) >>> I.has(x) True >>> x in I.free_symbols False >>> I.as_independent(x) == (I, 1) True >>> (I + x).as_independent(x) == (I, x) True Note: when trying to get independent terms, a separation method might need to be used first. In this case, it is important to keep track of what you send to this routine so you know how to interpret the returned values >>> from sympy import separatevars, log >>> separatevars(exp(x+y)).as_independent(x) (exp(y), exp(x)) >>> (x + xy).as_independent(y) (x, xy) >>> separatevars(x + xy).as_independent(y) (x, y + 1) >>> (x(1 + y)).as_independent(y) (x, y + 1) >>> (x(1 + y)).expand(mul=True).as_independent(y) (x, xy) >>> a, b=symbols('a b', positive=True) >>> (log(ab).expand(log=True)).as_independent(b) (log(a), log(b)) See Also ======== .separatevars(), .expand(log=True), Add.as_two_terms(), Mul.as_two_terms(), .as_coeff_add(), .as_coeff_mul() """ from .symbol import Symbol from .add import _unevaluated_Add from .mul import _unevaluated_Mul from sympy.utilities.iterables import sift if self.is_zero: return S.Zero, S.Zero func = self.func if hint.get('as_Add', isinstance(self, Add) ): want = Add else: want = Mul # sift out deps into symbolic and other and ignore # all symbols but those that are in the free symbols sym = set() other = [] for d in deps: if isinstance(d, Symbol): # Symbol.is_Symbol is True sym.add(d) else: other.append(d) def has(e): """return the standard has() if there are no literal symbols, else check to see that symbol-deps are in the free symbols.""" has_other = e.has(other) if not sym: return has_other return has_other or e.has((e.free_symbols & sym)) if (want is not func or func is not Add and func is not Mul): if has(self): return (want.identity, self) else: return (self, want.identity) else: if func is Add: args = list(self.args) else: args, nc = self.args_cnc() d = sift(args, lambda x: has(x)) depend = d[True] indep = d[False] if func is Add: # all terms were treated as commutative return (Add(indep), _unevaluated_Add(depend)) else: # handle noncommutative by stopping at first dependent term for i, n in enumerate(nc): if has(n): depend.extend(nc[i:]) break indep.append(n) return Mul(indep), ( Mul(depend, evaluate=False) if nc else _unevaluated_Mul(depend)) def as_real_imag(self, deep=True, hints): """Performs complex expansion on 'self' and returns a tuple containing collected both real and imaginary parts. This method can't be confused with re() and im() functions, which does not perform complex expansion at evaluation. However it is possible to expand both re() and im() functions and get exactly the same results as with a single call to this function. >>> from sympy import symbols, I >>> x, y = symbols('x,y', real=True) >>> (x + yI).as_real_imag() (x, y) >>> from sympy.abc import z, w >>> (z + wI).as_real_imag() (re(z) - im(w), re(w) + im(z)) """ from sympy import im, re if hints.get('ignore') == self: return None else: return (re(self), im(self)) def as_powers_dict(self): """Return self as a dictionary of factors with each factor being treated as a power. The keys are the bases of the factors and the values, the corresponding exponents. The resulting dictionary should be used with caution if the expression is a Mul and contains non- commutative factors since the order that they appeared will be lost in the dictionary. See Also ======== as_ordered_factors: An alternative for noncommutative applications, returning an ordered list of factors. args_cnc: Similar to as_ordered_factors, but guarantees separation of commutative and noncommutative factors. """ d = defaultdict(int) d.update(dict([self.as_base_exp()])) return d def as_coefficients_dict(self): """Return a dictionary mapping terms to their Rational coefficient. Since the dictionary is a defaultdict, inquiries about terms which were not present will return a coefficient of 0. If an expression is not an Add it is considered to have a single term. Examples ======== >>> from sympy.abc import a, x >>> (3x + ax + 4).as_coefficients_dict() {1: 4, x: 3, ax: 1} >>> _[a] 0 >>> (3ax).as_coefficients_dict() {ax: 3} """ c, m = self.as_coeff_Mul() if not c.is_Rational: c = S.One m = self d = defaultdict(int) d.update({m: c}) return d def as_base_exp(self): # a -> b * e return self, S.One def as_coeff_mul(self, deps, kwargs): """Return the tuple (c, args) where self is written as a Mul, ``m``. c should be a Rational multiplied by any factors of the Mul that are independent of deps. args should be a tuple of all other factors of m; args is empty if self is a Number or if self is independent of deps (when given). This should be used when you don't know if self is a Mul or not but you want to treat self as a Mul or if you want to process the individual arguments of the tail of self as a Mul. - if you know self is a Mul and want only the head, use self.args[0]; - if you don't want to process the arguments of the tail but need the tail then use self.as_two_terms() which gives the head and tail; - if you want to split self into an independent and dependent parts use ``self.as_independent(deps)`` >>> from sympy import S >>> from sympy.abc import x, y >>> (S(3)).as_coeff_mul() (3, ()) >>> (3xy).as_coeff_mul() (3, (x, y)) >>> (3xy).as_coeff_mul(x) (3y, (x,)) >>> (3y).as_coeff_mul(x) (3y, ()) """ if deps: if not self.has(deps): return self, tuple() return S.One, (self,) def as_coeff_add(self, deps): """Return the tuple (c, args) where self is written as an Add, ``a``. c should be a Rational added to any terms of the Add that are independent of deps. args should be a tuple of all other terms of ``a``; args is empty if self is a Number or if self is independent of deps (when given). This should be used when you don't know if self is an Add or not but you want to treat self as an Add or if you want to process the individual arguments of the tail of self as an Add. - if you know self is an Add and want only the head, use self.args[0]; - if you don't want to process the arguments of the tail but need the tail then use self.as_two_terms() which gives the head and tail. - if you want to split self into an independent and dependent parts use ``self.as_independent(deps)`` >>> from sympy import S >>> from sympy.abc import x, y >>> (S(3)).as_coeff_add() (3, ()) >>> (3 + x).as_coeff_add() (3, (x,)) >>> (3 + x + y).as_coeff_add(x) (y + 3, (x,)) >>> (3 + y).as_coeff_add(x) (y + 3, ()) """ if deps: if not self.has(deps): return self, tuple() return S.Zero, (self,) def primitive(self): """Return the positive Rational that can be extracted non-recursively from every term of self (i.e., self is treated like an Add). This is like the as_coeff_Mul() method but primitive always extracts a positive Rational (never a negative or a Float). Examples ======== >>> from sympy.abc import x >>> (3(x + 1)2).primitive() (3, (x + 1)2) >>> a = (6x + 2); a.primitive() (2, 3x + 1) >>> b = (x/2 + 3); b.primitive() (1/2, x + 6) >>> (ab).primitive() == (1, ab) True """ if not self: return S.One, S.Zero c, r = self.as_coeff_Mul(rational=True) if c.is_negative: c, r = -c, -r return c, r def as_content_primitive(self, radical=False, clear=True): """This method should recursively remove a Rational from all arguments and return that (content) and the new self (primitive). The content should always be positive and ``Mul(foo.as_content_primitive()) == foo``. The primitive need not be in canonical form and should try to preserve the underlying structure if possible (i.e. expand_mul should not be applied to self). Examples ======== >>> from sympy import sqrt >>> from sympy.abc import x, y, z >>> eq = 2 + 2x + 2y(3 + 3y) The as_content_primitive function is recursive and retains structure: >>> eq.as_content_primitive() (2, x + 3y(y + 1) + 1) Integer powers will have Rationals extracted from the base: >>> ((2 + 6x)*2).as_content_primitive() (4, (3x + 1)*2) >>> ((2 + 6x)*(2y)).as_content_primitive() (1, (2(3x + 1))*(2y)) Terms may end up joining once their as_content_primitives are added: >>> ((5(x(1 + y)) + 2x(3 + 3y))).as_content_primitive() (11, x(y + 1)) >>> ((3(x(1 + y)) + 2x(3 + 3y))).as_content_primitive() (9, x(y + 1)) >>> ((3(z(1 + y)) + 2.0x(3 + 3y))).as_content_primitive() (1, 6.0x(y + 1) + 3z(y + 1)) >>> ((5(x(1 + y)) + 2x(3 + 3y))2).as_content_primitive() (121, x2(y + 1)2) >>> ((5(x(1 + y)) + 2.0x(3 + 3y))*2).as_content_primitive() (1, 121.0x*2(y + 1)*2) Radical content can also be factored out of the primitive: >>> (2sqrt(2) + 4sqrt(10)).as_content_primitive(radical=True) (2, sqrt(2)(1 + 2sqrt(5))) If clear=False (default is True) then content will not be removed from an Add if it can be distributed to leave one or more terms with integer coefficients. >>> (x/2 + y).as_content_primitive() (1/2, x + 2y) >>> (x/2 + y).as_content_primitive(clear=False) (1, x/2 + y) """ return S.One, self def as_numer_denom(self): """ expression -> a/b -> a, b This is just a stub that should be defined by an object's class methods to get anything else. See Also ======== normal: return a/b instead of a, b """ return self, S.One def normal(self): from .mul import _unevaluated_Mul n, d = self.as_numer_denom() if d is S.One: return n if d.is_Number: return _unevaluated_Mul(n, 1/d) else: return n/d def extract_multiplicatively(self, c): """Return None if it's not possible to make self in the form c * something in a nice way, i.e. preserving the properties of arguments of self. Examples ======== >>> from sympy import symbols, Rational >>> x, y = symbols('x,y', real=True) >>> ((xy)3).extract_multiplicatively(x2 y) xy2 >>> ((xy)3).extract_multiplicatively(x4 * y) >>> (2x).extract_multiplicatively(2) x >>> (2x).extract_multiplicatively(3) >>> (Rational(1, 2)x).extract_multiplicatively(3) x/6 """ c = sympify(c) if self is S.NaN: return None if c is S.One: return self elif c == self: return S.One if c.is_Add: cc, pc = c.primitive() if cc is not S.One: c = Mul(cc, pc, evaluate=False) if c.is_Mul: a, b = c.as_two_terms() x = self.extract_multiplicatively(a) if x is not None: return x.extract_multiplicatively(b) quotient = self / c if self.is_Number: if self is S.Infinity: if c.is_positive: return S.Infinity elif self is S.NegativeInfinity: if c.is_negative: return S.Infinity elif c.is_positive: return S.NegativeInfinity elif self is S.ComplexInfinity: if not c.is_zero: return S.ComplexInfinity elif self.is_Integer: if not quotient.is_Integer: return None elif self.is_positive and quotient.is_negative: return None else: return quotient elif self.is_Rational: if not quotient.is_Rational: return None elif self.is_positive and quotient.is_negative: return None else: return quotient elif self.is_Float: if not quotient.is_Float: return None elif self.is_positive and quotient.is_negative: return None else: return quotient elif self.is_NumberSymbol or self.is_Symbol or self is S.ImaginaryUnit: if quotient.is_Mul and len(quotient.args) == 2: if quotient.args[0].is_Integer and quotient.args[0].is_positive and quotient.args[1] == self: return quotient elif quotient.is_Integer and c.is_Number: return quotient elif self.is_Add: cs, ps = self.primitive() # assert cs >= 1 if c.is_Number and c is not S.NegativeOne: # assert c != 1 (handled at top) if cs is not S.One: if c.is_negative: xc = -(cs.extract_multiplicatively(-c)) else: xc = cs.extract_multiplicatively(c) if xc is not None: return xcps # rely on 2-arg Mul to restore Add return # \|c\| != 1 can only be extracted from cs if c == ps: return cs # check args of ps newargs = [] for arg in ps.args: newarg = arg.extract_multiplicatively(c) if newarg is None: return # all or nothing newargs.append(newarg) # args should be in same order so use unevaluated return if cs is not S.One: return Add._from_args([cst for t in newargs]) else: return Add._from_args(newargs) elif self.is_Mul: args = list(self.args) for i, arg in enumerate(args): newarg = arg.extract_multiplicatively(c) if newarg is not None: args[i] = newarg return Mul(args) elif self.is_Pow: if c.is_Pow and c.base == self.base: new_exp = self.exp.extract_additively(c.exp) if new_exp is not None: return self.base (new_exp) elif c == self.base: new_exp = self.exp.extract_additively(1) if new_exp is not None: return self.base (new_exp) def extract_additively(self, c): """Return self - c if it's possible to subtract c from self and make all matching coefficients move towards zero, else return None. Examples ======== >>> from sympy.abc import x, y >>> e = 2x + 3 >>> e.extract_additively(x + 1) x + 2 >>> e.extract_additively(3x) >>> e.extract_additively(4) >>> (y(x + 1)).extract_additively(x + 1) >>> ((x + 1)(x + 2y + 1) + 3).extract_additively(x + 1) (x + 1)(x + 2y) + 3 Sometimes auto-expansion will return a less simplified result than desired; gcd_terms might be used in such cases: >>> from sympy import gcd_terms >>> (4x(y + 1) + y).extract_additively(x) 4x(y + 1) + x(4y + 3) - x(4y + 4) + y >>> gcd_terms(_) x(4y + 3) + y See Also ======== extract_multiplicatively coeff as_coefficient """ c = sympify(c) if self is S.NaN: return None if c is S.Zero: return self elif c == self: return S.Zero elif self is S.Zero: return None if self.is_Number: if not c.is_Number: return None co = self diff = co - c # XXX should we match types? i.e should 3 - .1 succeed? if (co > 0 and diff > 0 and diff < co or co < 0 and diff < 0 and diff > co): return diff return None if c.is_Number: co, t = self.as_coeff_Add() xa = co.extract_additively(c) if xa is None: return None return xa + t # handle the args[0].is_Number case separately # since we will have trouble looking for the coeff of # a number. if c.is_Add and c.args[0].is_Number: # whole term as a term factor co = self.coeff(c) xa0 = (co.extract_additively(1) or 0)c if xa0: diff = self - coc return (xa0 + (diff.extract_additively(c) or diff)) or None # term-wise h, t = c.as_coeff_Add() sh, st = self.as_coeff_Add() xa = sh.extract_additively(h) if xa is None: return None xa2 = st.extract_additively(t) if xa2 is None: return None return xa + xa2 # whole term as a term factor co = self.coeff(c) xa0 = (co.extract_additively(1) or 0)c if xa0: diff = self - coc return (xa0 + (diff.extract_additively(c) or diff)) or None # term-wise coeffs = [] for a in Add.make_args(c): ac, at = a.as_coeff_Mul() co = self.coeff(at) if not co: return None coc, cot = co.as_coeff_Add() xa = coc.extract_additively(ac) if xa is None: return None self -= coat coeffs.append((cot + xa)at) coeffs.append(self) return Add(coeffs) @property def expr_free_symbols(self): """ Like ``free_symbols``, but returns the free symbols only if they are contained in an expression node. Examples ======== >>> from sympy.abc import x, y >>> (x + y).expr_free_symbols {x, y} If the expression is contained in a non-expression object, don't return the free symbols. Compare: >>> from sympy import Tuple >>> t = Tuple(x + y) >>> t.expr_free_symbols set() >>> t.free_symbols {x, y} """ return {j for i in self.args for j in i.expr_free_symbols} def could_extract_minus_sign(self): """Return True if self is not in a canonical form with respect to its sign. For most expressions, e, there will be a difference in e and -e. When there is, True will be returned for one and False for the other; False will be returned if there is no difference. Examples ======== >>> from sympy.abc import x, y >>> e = x - y >>> {i.could_extract_minus_sign() for i in (e, -e)} {False, True} """ negative_self = -self if self == negative_self: return False # e.g. zoox == -zoox self_has_minus = (self.extract_multiplicatively(-1) is not None) negative_self_has_minus = ( (negative_self).extract_multiplicatively(-1) is not None) if self_has_minus != negative_self_has_minus: return self_has_minus else: if self.is_Add: # We choose the one with less arguments with minus signs all_args = len(self.args) negative_args = len([False for arg in self.args if arg.could_extract_minus_sign()]) positive_args = all_args - negative_args if positive_args > negative_args: return False elif positive_args < negative_args: return True elif self.is_Mul: # We choose the one with an odd number of minus signs num, den = self.as_numer_denom() args = Mul.make_args(num) + Mul.make_args(den) arg_signs = [arg.could_extract_minus_sign() for arg in args] negative_args = list(filter(None, arg_signs)) return len(negative_args) % 2 == 1 # As a last resort, we choose the one with greater value of .sort_key() return bool(self.sort_key() < negative_self.sort_key()) def extract_branch_factor(self, allow_half=False): """ Try to write self as ``exp_polar(2piIn)z`` in a nice way. Return (z, n). >>> from sympy import exp_polar, I, pi >>> from sympy.abc import x, y >>> exp_polar(Ipi).extract_branch_factor() (exp_polar(Ipi), 0) >>> exp_polar(2Ipi).extract_branch_factor() (1, 1) >>> exp_polar(-piI).extract_branch_factor() (exp_polar(Ipi), -1) >>> exp_polar(3piI + x).extract_branch_factor() (exp_polar(x + Ipi), 1) >>> (yexp_polar(-5piI)exp_polar(3piI + 2pix)).extract_branch_factor() (yexp_polar(2pix), -1) >>> exp_polar(-Ipi/2).extract_branch_factor() (exp_polar(-Ipi/2), 0) If allow_half is True, also extract exp_polar(Ipi): >>> exp_polar(Ipi).extract_branch_factor(allow_half=True) (1, 1/2) >>> exp_polar(2Ipi).extract_branch_factor(allow_half=True) (1, 1) >>> exp_polar(3Ipi).extract_branch_factor(allow_half=True) (1, 3/2) >>> exp_polar(-Ipi).extract_branch_factor(allow_half=True) (1, -1/2) """ from sympy import exp_polar, pi, I, ceiling, Add n = S(0) res = S(1) args = Mul.make_args(self) exps = [] for arg in args: if isinstance(arg, exp_polar): exps += [arg.exp] else: res = arg piimult = S(0) extras = [] while exps: exp = exps.pop() if exp.is_Add: exps += exp.args continue if exp.is_Mul: coeff = exp.as_coefficient(piI) if coeff is not None: piimult += coeff continue extras += [exp] if not piimult.free_symbols: coeff = piimult tail = () else: coeff, tail = piimult.as_coeff_add(piimult.free_symbols) # round down to nearest multiple of 2 branchfact = ceiling(coeff/2 - S(1)/2)2 n += branchfact/2 c = coeff - branchfact if allow_half: nc = c.extract_additively(1) if nc is not None: n += S(1)/2 c = nc newexp = piIAdd(((c, ) + tail)) + Add(extras) if newexp != 0: res = exp_polar(newexp) return res, n def _eval_is_polynomial(self, syms): if self.free_symbols.intersection(syms) == set([]): return True return False def is_polynomial(self, syms): r""" Return True if self is a polynomial in syms and False otherwise. This checks if self is an exact polynomial in syms. This function returns False for expressions that are "polynomials" with symbolic exponents. Thus, you should be able to apply polynomial algorithms to expressions for which this returns True, and Poly(expr, \syms) should work if and only if expr.is_polynomial(\syms) returns True. The polynomial does not have to be in expanded form. If no symbols are given, all free symbols in the expression will be used. This is not part of the assumptions system. You cannot do Symbol('z', polynomial=True). Examples ======== >>> from sympy import Symbol >>> x = Symbol('x') >>> ((x2 + 1)4).is_polynomial(x) True >>> ((x2 + 1)4).is_polynomial() True >>> (2x + 1).is_polynomial(x) False >>> n = Symbol('n', nonnegative=True, integer=True) >>> (xn + 1).is_polynomial(x) False This function does not attempt any nontrivial simplifications that may result in an expression that does not appear to be a polynomial to become one. >>> from sympy import sqrt, factor, cancel >>> y = Symbol('y', positive=True) >>> a = sqrt(y2 + 2y + 1) >>> a.is_polynomial(y) False >>> factor(a) y + 1 >>> factor(a).is_polynomial(y) True >>> b = (y*2 + 2y + 1)/(y + 1) >>> b.is_polynomial(y) False >>> cancel(b) y + 1 >>> cancel(b).is_polynomial(y) True See also .is_rational_function() """ if syms: syms = set(map(sympify, syms)) else: syms = self.free_symbols if syms.intersection(self.free_symbols) == set([]): # constant polynomial return True else: return self._eval_is_polynomial(syms) def _eval_is_rational_function(self, syms): if self.free_symbols.intersection(syms) == set([]): return True return False def is_rational_function(self, syms): """ Test whether function is a ratio of two polynomials in the given symbols, syms. When syms is not given, all free symbols will be used. The rational function does not have to be in expanded or in any kind of canonical form. This function returns False for expressions that are "rational functions" with symbolic exponents. Thus, you should be able to call .as_numer_denom() and apply polynomial algorithms to the result for expressions for which this returns True. This is not part of the assumptions system. You cannot do Symbol('z', rational_function=True). Examples ======== >>> from sympy import Symbol, sin >>> from sympy.abc import x, y >>> (x/y).is_rational_function() True >>> (x2).is_rational_function() True >>> (x/sin(y)).is_rational_function(y) False >>> n = Symbol('n', integer=True) >>> (xn + 1).is_rational_function(x) False This function does not attempt any nontrivial simplifications that may result in an expression that does not appear to be a rational function to become one. >>> from sympy import sqrt, factor >>> y = Symbol('y', positive=True) >>> a = sqrt(y2 + 2y + 1)/y >>> a.is_rational_function(y) False >>> factor(a) (y + 1)/y >>> factor(a).is_rational_function(y) True See also is_algebraic_expr(). """ if self in [S.NaN, S.Infinity, -S.Infinity, S.ComplexInfinity]: return False if syms: syms = set(map(sympify, syms)) else: syms = self.free_symbols if syms.intersection(self.free_symbols) == set([]): # constant rational function return True else: return self._eval_is_rational_function(syms) def _eval_is_algebraic_expr(self, syms): if self.free_symbols.intersection(syms) == set([]): return True return False def is_algebraic_expr(self, syms): """ This tests whether a given expression is algebraic or not, in the given symbols, syms. When syms is not given, all free symbols will be used. The rational function does not have to be in expanded or in any kind of canonical form. This function returns False for expressions that are "algebraic expressions" with symbolic exponents. This is a simple extension to the is_rational_function, including rational exponentiation. Examples ======== >>> from sympy import Symbol, sqrt >>> x = Symbol('x', real=True) >>> sqrt(1 + x).is_rational_function() False >>> sqrt(1 + x).is_algebraic_expr() True This function does not attempt any nontrivial simplifications that may result in an expression that does not appear to be an algebraic expression to become one. >>> from sympy import exp, factor >>> a = sqrt(exp(x)2 + 2exp(x) + 1)/(exp(x) + 1) >>> a.is_algebraic_expr(x) False >>> factor(a).is_algebraic_expr() True See Also ======== is_rational_function() References ========== - https://en.wikipedia.org/wiki/Algebraic_expression """ if syms: syms = set(map(sympify, syms)) else: syms = self.free_symbols if syms.intersection(self.free_symbols) == set([]): # constant algebraic expression return True else: return self._eval_is_algebraic_expr(syms) ################################################################################### ##################### SERIES, LEADING TERM, LIMIT, ORDER METHODS ################## ################################################################################### def series(self, x=None, x0=0, n=6, dir="+", logx=None): """ Series expansion of "self" around ``x = x0`` yielding either terms of the series one by one (the lazy series given when n=None), else all the terms at once when n != None. Returns the series expansion of "self" around the point ``x = x0`` with respect to ``x`` up to ``O((x - x0)n, x, x0)`` (default n is 6). If ``x=None`` and ``self`` is univariate, the univariate symbol will be supplied, otherwise an error will be raised. >>> from sympy import cos, exp >>> from sympy.abc import x, y >>> cos(x).series() 1 - x2/2 + x4/24 + O(x6) >>> cos(x).series(n=4) 1 - x2/2 + O(x4) >>> cos(x).series(x, x0=1, n=2) cos(1) - (x - 1)sin(1) + O((x - 1)2, (x, 1)) >>> e = cos(x + exp(y)) >>> e.series(y, n=2) cos(x + 1) - ysin(x + 1) + O(y*2) >>> e.series(x, n=2) cos(exp(y)) - xsin(exp(y)) + O(x2) If ``n=None`` then a generator of the series terms will be returned. >>> term=cos(x).series(n=None) >>> [next(term) for i in range(2)] [1, -x2/2] For ``dir=+`` (default) the series is calculated from the right and for ``dir=-`` the series from the left. For smooth functions this flag will not alter the results. >>> abs(x).series(dir="+") x >>> abs(x).series(dir="-") -x """ from sympy import collect, Dummy, Order, Rational, Symbol, ceiling if x is None: syms = self.free_symbols if not syms: return self elif len(syms) > 1: raise ValueError('x must be given for multivariate functions.') x = syms.pop() if isinstance(x, Symbol): dep = x in self.free_symbols else: d = Dummy() dep = d in self.xreplace({x: d}).free_symbols if not dep: if n is None: return (s for s in [self]) else: return self if len(dir) != 1 or dir not in '+-': raise ValueError("Dir must be '+' or '-'") if x0 in [S.Infinity, S.NegativeInfinity]: sgn = 1 if x0 is S.Infinity else -1 s = self.subs(x, sgn/x).series(x, n=n, dir='+') if n is None: return (si.subs(x, sgn/x) for si in s) return s.subs(x, sgn/x) # use rep to shift origin to x0 and change sign (if dir is negative) # and undo the process with rep2 if x0 or dir == '-': if dir == '-': rep = -x + x0 rep2 = -x rep2b = x0 else: rep = x + x0 rep2 = x rep2b = -x0 s = self.subs(x, rep).series(x, x0=0, n=n, dir='+', logx=logx) if n is None: # lseries... return (si.subs(x, rep2 + rep2b) for si in s) return s.subs(x, rep2 + rep2b) # from here on it's x0=0 and dir='+' handling if x.is_positive is x.is_negative is None or x.is_Symbol is not True: # replace x with an x that has a positive assumption xpos = Dummy('x', positive=True, finite=True) rv = self.subs(x, xpos).series(xpos, x0, n, dir, logx=logx) if n is None: return (s.subs(xpos, x) for s in rv) else: return rv.subs(xpos, x) if n is not None: # nseries handling s1 = self._eval_nseries(x, n=n, logx=logx) o = s1.getO() or S.Zero if o: # make sure the requested order is returned ngot = o.getn() if ngot > n: # leave o in its current form (e.g. with xlog(x)) so # it eats terms properly, then replace it below if n != 0: s1 += o.subs(x, xRational(n, ngot)) else: s1 += Order(1, x) elif ngot < n: # increase the requested number of terms to get the desired # number keep increasing (up to 9) until the received order # is different than the original order and then predict how # many additional terms are needed for more in range(1, 9): s1 = self._eval_nseries(x, n=n + more, logx=logx) newn = s1.getn() if newn != ngot: ndo = n + ceiling((n - ngot)more/(newn - ngot)) s1 = self._eval_nseries(x, n=ndo, logx=logx) while s1.getn() < n: s1 = self._eval_nseries(x, n=ndo, logx=logx) ndo += 1 break else: raise ValueError('Could not calculate %s terms for %s' % (str(n), self)) s1 += Order(xn, x) o = s1.getO() s1 = s1.removeO() else: o = Order(xn, x) s1done = s1.doit() if (s1done + o).removeO() == s1done: o = S.Zero try: return collect(s1, x) + o except NotImplementedError: return s1 + o else: # lseries handling def yield_lseries(s): """Return terms of lseries one at a time.""" for si in s: if not si.is_Add: yield si continue # yield terms 1 at a time if possible # by increasing order until all the # terms have been returned yielded = 0 o = Order(si, x)x ndid = 0 ndo = len(si.args) while 1: do = (si - yielded + o).removeO() o = x if not do or do.is_Order: continue if do.is_Add: ndid += len(do.args) else: ndid += 1 yield do if ndid == ndo: break yielded += do return yield_lseries(self.removeO()._eval_lseries(x, logx=logx)) def taylor_term(self, n, x, previous_terms): """General method for the taylor term. This method is slow, because it differentiates n-times. Subclasses can redefine it to make it faster by using the "previous_terms". """ from sympy import Dummy, factorial x = sympify(x) _x = Dummy('x') return self.subs(x, _x).diff(_x, n).subs(_x, x).subs(x, 0) xn / factorial(n) def lseries(self, x=None, x0=0, dir='+', logx=None): """ Wrapper for series yielding an iterator of the terms of the series. Note: an infinite series will yield an infinite iterator. The following, for exaxmple, will never terminate. It will just keep printing terms of the sin(x) series:: for term in sin(x).lseries(x): print term The advantage of lseries() over nseries() is that many times you are just interested in the next term in the series (i.e. the first term for example), but you don't know how many you should ask for in nseries() using the "n" parameter. See also nseries(). """ return self.series(x, x0, n=None, dir=dir, logx=logx) def _eval_lseries(self, x, logx=None): # default implementation of lseries is using nseries(), and adaptively # increasing the "n". As you can see, it is not very efficient, because # we are calculating the series over and over again. Subclasses should # override this method and implement much more efficient yielding of # terms. n = 0 series = self._eval_nseries(x, n=n, logx=logx) if not series.is_Order: if series.is_Add: yield series.removeO() else: yield series return while series.is_Order: n += 1 series = self._eval_nseries(x, n=n, logx=logx) e = series.removeO() yield e while 1: while 1: n += 1 series = self._eval_nseries(x, n=n, logx=logx).removeO() if e != series: break yield series - e e = series def nseries(self, x=None, x0=0, n=6, dir='+', logx=None): """ Wrapper to _eval_nseries if assumptions allow, else to series. If x is given, x0 is 0, dir='+', and self has x, then _eval_nseries is called. This calculates "n" terms in the innermost expressions and then builds up the final series just by "cross-multiplying" everything out. The optional ``logx`` parameter can be used to replace any log(x) in the returned series with a symbolic value to avoid evaluating log(x) at 0. A symbol to use in place of log(x) should be provided. Advantage -- it's fast, because we don't have to determine how many terms we need to calculate in advance. Disadvantage -- you may end up with less terms than you may have expected, but the O(xn) term appended will always be correct and so the result, though perhaps shorter, will also be correct. If any of those assumptions is not met, this is treated like a wrapper to series which will try harder to return the correct number of terms. See also lseries(). Examples ======== >>> from sympy import sin, log, Symbol >>> from sympy.abc import x, y >>> sin(x).nseries(x, 0, 6) x - x3/6 + x5/120 + O(x6) >>> log(x+1).nseries(x, 0, 5) x - x2/2 + x3/3 - x4/4 + O(x5) Handling of the ``logx`` parameter --- in the following example the expansion fails since ``sin`` does not have an asymptotic expansion at -oo (the limit of log(x) as x approaches 0): >>> e = sin(log(x)) >>> e.nseries(x, 0, 6) Traceback (most recent call last): ... PoleError: ... ... >>> logx = Symbol('logx') >>> e.nseries(x, 0, 6, logx=logx) sin(logx) In the following example, the expansion works but gives only an Order term unless the ``logx`` parameter is used: >>> e = xy >>> e.nseries(x, 0, 2) O(log(x)*2) >>> e.nseries(x, 0, 2, logx=logx) exp(logxy) """ if x and not x in self.free_symbols: return self if x is None or x0 or dir != '+': # {see XPOS above} or (x.is_positive == x.is_negative == None): return self.series(x, x0, n, dir) else: return self._eval_nseries(x, n=n, logx=logx) def _eval_nseries(self, x, n, logx): """ Return terms of series for self up to O(xn) at x=0 from the positive direction. This is a method that should be overridden in subclasses. Users should never call this method directly (use .nseries() instead), so you don't have to write docstrings for _eval_nseries(). """ from sympy.utilities.misc import filldedent raise NotImplementedError(filldedent(""" The _eval_nseries method should be added to %s to give terms up to O(xn) at x=0 from the positive direction so it is available when nseries calls it.""" % self.func) ) def limit(self, x, xlim, dir='+'): """ Compute limit x->xlim. """ from sympy.series.limits import limit return limit(self, x, xlim, dir) def compute_leading_term(self, x, logx=None): """ as_leading_term is only allowed for results of .series() This is a wrapper to compute a series first. """ from sympy import Dummy, log from sympy.series.gruntz import calculate_series if self.removeO() == 0: return self if logx is None: d = Dummy('logx') s = calculate_series(self, x, d).subs(d, log(x)) else: s = calculate_series(self, x, logx) return s.as_leading_term(x) @cacheit def as_leading_term(self, symbols): """ Returns the leading (nonzero) term of the series expansion of self. The _eval_as_leading_term routines are used to do this, and they must always return a non-zero value. Examples ======== >>> from sympy.abc import x >>> (1 + x + x2).as_leading_term(x) 1 >>> (1/x2 + x + x2).as_leading_term(x) x(-2) """ from sympy import powsimp if len(symbols) > 1: c = self for x in symbols: c = c.as_leading_term(x) return c elif not symbols: return self x = sympify(symbols[0]) if not x.is_symbol: raise ValueError('expecting a Symbol but got %s' % x) if x not in self.free_symbols: return self obj = self._eval_as_leading_term(x) if obj is not None: return powsimp(obj, deep=True, combine='exp') raise NotImplementedError('as_leading_term(%s, %s)' % (self, x)) def _eval_as_leading_term(self, x): return self def as_coeff_exponent(self, x): """ ``cx*e -> c,e`` where x can be any symbolic expression. """ from sympy import collect s = collect(self, x) c, p = s.as_coeff_mul(x) if len(p) == 1: b, e = p[0].as_base_exp() if b == x: return c, e return s, S.Zero def leadterm(self, x): """ Returns the leading term axb as a tuple (a, b). Examples ======== >>> from sympy.abc import x >>> (1+x+x2).leadterm(x) (1, 0) >>> (1/x2+x+x2).leadterm(x) (1, -2) """ from sympy import Dummy, log l = self.as_leading_term(x) d = Dummy('logx') if l.has(log(x)): l = l.subs(log(x), d) c, e = l.as_coeff_exponent(x) if x in c.free_symbols: from sympy.utilities.misc import filldedent raise ValueError(filldedent(""" cannot compute leadterm(%s, %s). The coefficient should have been free of x but got %s""" % (self, x, c))) c = c.subs(d, log(x)) return c, e def as_coeff_Mul(self, rational=False): """Efficiently extract the coefficient of a product. """ return S.One, self def as_coeff_Add(self, rational=False): """Efficiently extract the coefficient of a summation. """ return S.Zero, self def fps(self, x=None, x0=0, dir=1, hyper=True, order=4, rational=True, full=False): """ Compute formal power power series of self. See the docstring of the :func:`fps` function in sympy.series.formal for more information. """ from sympy.series.formal import fps return fps(self, x, x0, dir, hyper, order, rational, full) def fourier_series(self, limits=None): """Compute fourier sine/cosine series of self. See the docstring of the :func:`fourier_series` in sympy.series.fourier for more information. """ from sympy.series.fourier import fourier_series return fourier_series(self, limits) ################################################################################### ##################### DERIVATIVE, INTEGRAL, FUNCTIONAL METHODS #################### ################################################################################### def diff(self, symbols, assumptions): assumptions.setdefault("evaluate", True) return Derivative(self, symbols, assumptions) ########################################################################### ###################### EXPRESSION EXPANSION METHODS ####################### ########################################################################### # Relevant subclasses should override _eval_expand_hint() methods. See # the docstring of expand() for more info. def _eval_expand_complex(self, hints): real, imag = self.as_real_imag(*hints) return real + S.ImaginaryUnitimag @staticmethod def _expand_hint(expr, hint, deep=True, hints): """ Helper for ``expand()``. Recursively calls ``expr._eval_expand_hint()``. Returns ``(expr, hit)``, where expr is the (possibly) expanded ``expr`` and ``hit`` is ``True`` if ``expr`` was truly expanded and ``False`` otherwise. """ hit = False # XXX: Hack to support non-Basic args # \| # V if deep and getattr(expr, 'args', ()) and not expr.is_Atom: sargs = [] for arg in expr.args: arg, arghit = Expr._expand_hint(arg, hint, hints) hit \|= arghit sargs.append(arg) if hit: expr = expr.func(sargs) if hasattr(expr, hint): newexpr = getattr(expr, hint)(hints) if newexpr != expr: return (newexpr, True) return (expr, hit) @cacheit def expand(self, deep=True, modulus=None, power_base=True, power_exp=True, mul=True, log=True, multinomial=True, basic=True, hints): """ Expand an expression using hints. See the docstring of the expand() function in sympy.core.function for more information. """ from sympy.simplify.radsimp import fraction hints.update(power_base=power_base, power_exp=power_exp, mul=mul, log=log, multinomial=multinomial, basic=basic) expr = self if hints.pop('frac', False): n, d = [a.expand(deep=deep, modulus=modulus, hints) for a in fraction(self)] return n/d elif hints.pop('denom', False): n, d = fraction(self) return n/d.expand(deep=deep, modulus=modulus, hints) elif hints.pop('numer', False): n, d = fraction(self) return n.expand(deep=deep, modulus=modulus, hints)/d # Although the hints are sorted here, an earlier hint may get applied # at a given node in the expression tree before another because of how # the hints are applied. e.g. expand(log(x(y + z))) -> log(xy + # xz) because while applying log at the top level, log and mul are # applied at the deeper level in the tree so that when the log at the # upper level gets applied, the mul has already been applied at the # lower level. # Additionally, because hints are only applied once, the expression # may not be expanded all the way. For example, if mul is applied # before multinomial, x(x + 1)2 won't be expanded all the way. For # now, we just use a special case to make multinomial run before mul, # so that at least polynomials will be expanded all the way. In the # future, smarter heuristics should be applied. # TODO: Smarter heuristics def _expand_hint_key(hint): """Make multinomial come before mul""" if hint == 'mul': return 'mulz' return hint for hint in sorted(hints.keys(), key=_expand_hint_key): use_hint = hints[hint] if use_hint: hint = '_eval_expand_' + hint expr, hit = Expr._expand_hint(expr, hint, deep=deep, hints) while True: was = expr if hints.get('multinomial', False): expr, _ = Expr._expand_hint( expr, '_eval_expand_multinomial', deep=deep, hints) if hints.get('mul', False): expr, _ = Expr._expand_hint( expr, '_eval_expand_mul', deep=deep, hints) if hints.get('log', False): expr, _ = Expr._expand_hint( expr, '_eval_expand_log', deep=deep, hints) if expr == was: break if modulus is not None: modulus = sympify(modulus) if not modulus.is_Integer or modulus <= 0: raise ValueError( "modulus must be a positive integer, got %s" % modulus) terms = [] for term in Add.make_args(expr): coeff, tail = term.as_coeff_Mul(rational=True) coeff %= modulus if coeff: terms.append(coefftail) expr = Add(terms) return expr ########################################################################### ################### GLOBAL ACTION VERB WRAPPER METHODS #################### ########################################################################### def integrate(self, args, *kwargs): """See the integrate function in sympy.integrals""" from sympy.integrals import integrate return integrate(self, args, *kwargs) def simplify(self, ratio=1.7, measure=None, rational=False, inverse=False): """See the simplify function in sympy.simplify""" from sympy.simplify import simplify from sympy.core.function import count_ops measure = measure or count_ops return simplify(self, ratio, measure) def nsimplify(self, constants=[], tolerance=None, full=False): """See the nsimplify function in sympy.simplify""" from sympy.simplify import nsimplify return nsimplify(self, constants, tolerance, full) def separate(self, deep=False, force=False): """See the separate function in sympy.simplify""" from sympy.core.function import expand_power_base return expand_power_base(self, deep=deep, force=force) def collect(self, syms, func=None, evaluate=True, exact=False, distribute_order_term=True): """See the collect function in sympy.simplify""" from sympy.simplify import collect return collect(self, syms, func, evaluate, exact, distribute_order_term) def together(self, args, *kwargs): """See the together function in sympy.polys""" from sympy.polys import together return together(self, args, kwargs) def apart(self, x=None, args): """See the apart function in sympy.polys""" from sympy.polys import apart return apart(self, x, args) def ratsimp(self): """See the ratsimp function in sympy.simplify""" from sympy.simplify import ratsimp return ratsimp(self) def trigsimp(self, args): """See the trigsimp function in sympy.simplify""" from sympy.simplify import trigsimp return trigsimp(self, args) def radsimp(self, kwargs): """See the radsimp function in sympy.simplify""" from sympy.simplify import radsimp return radsimp(self, *kwargs) def powsimp(self, args, *kwargs): """See the powsimp function in sympy.simplify""" from sympy.simplify import powsimp return powsimp(self, args, *kwargs) def combsimp(self): """See the combsimp function in sympy.simplify""" from sympy.simplify import combsimp return combsimp(self) def gammasimp(self): """See the gammasimp function in sympy.simplify""" from sympy.simplify import gammasimp return gammasimp(self) def factor(self, gens, *args): """See the factor() function in sympy.polys.polytools""" from sympy.polys import factor return factor(self, gens, *args) def refine(self, assumption=True): """See the refine function in sympy.assumptions""" from sympy.assumptions import refine return refine(self, assumption) def cancel(self, gens, *args): """See the cancel function in sympy.polys""" from sympy.polys import cancel return cancel(self, gens, *args) def invert(self, g, gens, *args): """Return the multiplicative inverse of ``self`` mod ``g`` where ``self`` (and ``g``) may be symbolic expressions). See Also ======== sympy.core.numbers.mod_inverse, sympy.polys.polytools.invert """ from sympy.polys.polytools import invert from sympy.core.numbers import mod_inverse if self.is_number and getattr(g, 'is_number', True): return mod_inverse(self, g) return invert(self, g, gens, *args) def round(self, p=0): """Return x rounded to the given decimal place. If a complex number would results, apply round to the real and imaginary components of the number. Examples ======== >>> from sympy import pi, E, I, S, Add, Mul, Number >>> S(10.5).round() 11. >>> pi.round() 3. >>> pi.round(2) 3.14 >>> (2pi + EI).round() 6. + 3.I The round method has a chopping effect: >>> (2pi + I/10).round() 6. >>> (pi/10 + 2I).round() 2.I >>> (pi/10 + EI).round(2) 0.31 + 2.72I Notes ===== Do not confuse the Python builtin function, round, with the SymPy method of the same name. The former always returns a float (or raises an error if applied to a complex value) while the latter returns either a Number or a complex number: >>> isinstance(round(S(123), -2), Number) False >>> isinstance(S(123).round(-2), Number) True >>> isinstance((3I).round(), Mul) True >>> isinstance((1 + 3I).round(), Add) True """ from sympy import Float x = self if not x.is_number: raise TypeError("can't round symbolic expression") if not x.is_Atom: xn = x.n(2) if not pure_complex(xn, or_real=True): raise TypeError('Expected a number but got %s:' % getattr(getattr(x,'func', x), '__name__', type(x))) elif x in (S.NaN, S.Infinity, S.NegativeInfinity, S.ComplexInfinity): return x if not x.is_real: i, r = x.as_real_imag() return i.round(p) + S.ImaginaryUnitr.round(p) if not x: return x p = int(p) precs = [f._prec for f in x.atoms(Float)] dps = prec_to_dps(max(precs)) if precs else None mag_first_dig = _mag(x) allow = digits_needed = mag_first_dig + p if dps is not None and allow > dps: allow = dps mag = Pow(10, p) # magnitude needed to bring digit p to units place xwas = x x += 1/(2mag) # add the half for rounding i10 = 10magx.n((dps if dps is not None else digits_needed) + 1) if i10.is_negative: x = xwas - 1/(2mag) # should have gone the other way i10 = 10magx.n((dps if dps is not None else digits_needed) + 1) rv = -(Integer(-i10)//10) else: rv = Integer(i10)//10 q = 1 if p > 0: q = mag elif p < 0: rv /= mag rv = Rational(rv, q) if rv.is_Integer: # use str or else it won't be a float return Float(str(rv), digits_needed) else: if not allow and rv > self: allow += 1 return Float(rv, allow) class AtomicExpr(Atom, Expr): """ A parent class for object which are both atoms and Exprs. For example: Symbol, Number, Rational, Integer, ... But not: Add, Mul, Pow, ... """ is_number = False is_Atom = True __slots__ = [] def _eval_derivative(self, s): if self == s: return S.One return S.Zero def _eval_derivative_n_times(self, s, n): from sympy import Piecewise, Eq from sympy import Tuple from sympy.matrices.common import MatrixCommon if isinstance(s, (MatrixCommon, Tuple, Iterable)): return super(AtomicExpr, self)._eval_derivative_n_times(s, n) if self == s: return Piecewise((self, Eq(n, 0)), (1, Eq(n, 1)), (0, True)) else: return Piecewise((self, Eq(n, 0)), (0, True)) def _eval_is_polynomial(self, syms): return True def _eval_is_rational_function(self, syms): return True def _eval_is_algebraic_expr(self, syms): return True def _eval_nseries(self, x, n, logx): return self @property def expr_free_symbols(self): return {self} def _mag(x): """Return integer ``i`` such that .1 <= x/10i < 1 Examples ======== >>> from sympy.core.expr import _mag >>> from sympy import Float >>> _mag(Float(.1)) 0 >>> _mag(Float(.01)) -1 >>> _mag(Float(1234)) 4 """ from math import log10, ceil, log from sympy import Float xpos = abs(x.n()) if not xpos: return S.Zero try: mag_first_dig = int(ceil(log10(xpos))) except (ValueError, OverflowError): mag_first_dig = int(ceil(Float(mpf_log(xpos._mpf_, 53))/log(10))) # check that we aren't off by 1 if (xpos/10mag_first_dig) >= 1: assert 1 <= (xpos/10*mag_first_dig) < 10 mag_first_dig += 1 return mag_first_dig class UnevaluatedExpr(Expr): """ Expression that is not evaluated unless released. Examples ======== >>> from sympy import UnevaluatedExpr >>> from sympy.abc import a, b, x, y >>> x(1/x) 1 >>> xUnevaluatedExpr(1/x) x1/x """ def __new__(cls, arg, kwargs): arg = _sympify(arg) obj = Expr.__new__(cls, arg, kwargs) return obj def doit(self, kwargs): if kwargs.get("deep", True): return self.args[0].doit(kwargs) else: return self.args[0] def _n2(a, b): """Return (a - b).evalf(2) if a and b are comparable, else None. This should only be used when a and b are already sympified. """ # /!\ it is very important (see issue 8245) not to # use a re-evaluated number in the calculation of dif if a.is_comparable and b.is_comparable: dif = (a - b).evalf(2) if dif.is_comparable: return dif from .mul import Mul from .add import Add from .power import Pow from .function import Derivative, Function from .mod import Mod from .exprtools import factor_terms from .numbers import Integer, Rational
d13b5542ccd15a92a662caf6f235d4f7228d6fb116b4eec5a0e9a27d513abe5d	from __future__ import print_function, division from .add import _unevaluated_Add, Add from .basic import S from .compatibility import ordered from .expr import Expr from .evalf import EvalfMixin from .sympify import _sympify from .evaluate import global_evaluate from sympy.logic.boolalg import Boolean, BooleanAtom __all__ = ( 'Rel', 'Eq', 'Ne', 'Lt', 'Le', 'Gt', 'Ge', 'Relational', 'Equality', 'Unequality', 'StrictLessThan', 'LessThan', 'StrictGreaterThan', 'GreaterThan', ) # Note, see issue 4986. Ideally, we wouldn't want to subclass both Boolean # and Expr. def _canonical(cond): # return a condition in which all relationals are canonical try: reps = dict([(r, r.canonical) for r in cond.atoms(Relational)]) return cond.xreplace(reps) except AttributeError: return cond class Relational(Boolean, Expr, EvalfMixin): """Base class for all relation types. Subclasses of Relational should generally be instantiated directly, but Relational can be instantiated with a valid `rop` value to dispatch to the appropriate subclass. Parameters ========== rop : str or None Indicates what subclass to instantiate. Valid values can be found in the keys of Relational.ValidRelationalOperator. Examples ======== >>> from sympy import Rel >>> from sympy.abc import x, y >>> Rel(y, x + x2, '==') Eq(y, x2 + x) """ __slots__ = [] is_Relational = True # ValidRelationOperator - Defined below, because the necessary classes # have not yet been defined def __new__(cls, lhs, rhs, rop=None, assumptions): # If called by a subclass, do nothing special and pass on to Expr. if cls is not Relational: return Expr.__new__(cls, lhs, rhs, assumptions) # If called directly with an operator, look up the subclass # corresponding to that operator and delegate to it try: cls = cls.ValidRelationOperator[rop] rv = cls(lhs, rhs, *assumptions) # /// drop when Py2 is no longer supported # validate that Booleans are not being used in a relational # other than Eq/Ne; if isinstance(rv, (Eq, Ne)): pass elif isinstance(rv, Relational): # could it be otherwise? from sympy.core.symbol import Symbol from sympy.logic.boolalg import Boolean for a in rv.args: if isinstance(a, Symbol): continue if isinstance(a, Boolean): from sympy.utilities.misc import filldedent raise TypeError(filldedent(''' A Boolean argument can only be used in Eq and Ne; all other relationals expect real expressions. ''')) # \\\ return rv except KeyError: raise ValueError( "Invalid relational operator symbol: %r" % rop) @property def lhs(self): """The left-hand side of the relation.""" return self._args[0] @property def rhs(self): """The right-hand side of the relation.""" return self._args[1] @property def reversed(self): """Return the relationship with sides (and sign) reversed. Examples ======== >>> from sympy import Eq >>> from sympy.abc import x >>> Eq(x, 1) Eq(x, 1) >>> _.reversed Eq(1, x) >>> x < 1 x < 1 >>> _.reversed 1 > x """ ops = {Gt: Lt, Ge: Le, Lt: Gt, Le: Ge} a, b = self.args return ops.get(self.func, self.func)(b, a, evaluate=False) def _eval_evalf(self, prec): return self.func([s._evalf(prec) for s in self.args]) @property def canonical(self): """Return a canonical form of the relational by putting a Number on the rhs else ordering the args. No other simplification is attempted. Examples ======== >>> from sympy.abc import x, y >>> x < 2 x < 2 >>> _.reversed.canonical x < 2 >>> (-y < x).canonical x > -y >>> (-y > x).canonical x < -y """ args = self.args r = self if r.rhs.is_Number: if r.lhs.is_Number and r.lhs > r.rhs: r = r.reversed elif r.lhs.is_Number: r = r.reversed elif tuple(ordered(args)) != args: r = r.reversed return r def equals(self, other, failing_expression=False): """Return True if the sides of the relationship are mathematically identical and the type of relationship is the same. If failing_expression is True, return the expression whose truth value was unknown.""" if isinstance(other, Relational): if self == other or self.reversed == other: return True a, b = self, other if a.func in (Eq, Ne) or b.func in (Eq, Ne): if a.func != b.func: return False l, r = [i.equals(j, failing_expression=failing_expression) for i, j in zip(a.args, b.args)] if l is True: return r if r is True: return l lr, rl = [i.equals(j, failing_expression=failing_expression) for i, j in zip(a.args, b.reversed.args)] if lr is True: return rl if rl is True: return lr e = (l, r, lr, rl) if all(i is False for i in e): return False for i in e: if i not in (True, False): return i else: if b.func != a.func: b = b.reversed if a.func != b.func: return False l = a.lhs.equals(b.lhs, failing_expression=failing_expression) if l is False: return False r = a.rhs.equals(b.rhs, failing_expression=failing_expression) if r is False: return False if l is True: return r return l def _eval_simplify(self, ratio, measure, rational, inverse): r = self r = r.func([i.simplify(ratio=ratio, measure=measure, rational=rational, inverse=inverse) for i in r.args]) if r.is_Relational: dif = r.lhs - r.rhs # replace dif with a valid Number that will # allow a definitive comparison with 0 v = None if dif.is_comparable: v = dif.n(2) elif dif.equals(0): # XXX this is expensive v = S.Zero if v is not None: r = r.func._eval_relation(v, S.Zero) r = r.canonical if measure(r) < ratiomeasure(self): return r else: return self def __nonzero__(self): raise TypeError("cannot determine truth value of Relational") __bool__ = __nonzero__ def _eval_as_set(self): # self is univariate and periodicity(self, x) in (0, None) from sympy.solvers.inequalities import solve_univariate_inequality syms = self.free_symbols assert len(syms) == 1 x = syms.pop() return solve_univariate_inequality(self, x, relational=False) @property def binary_symbols(self): # override where necessary return set() Rel = Relational class Equality(Relational): """An equal relation between two objects. Represents that two objects are equal. If they can be easily shown to be definitively equal (or unequal), this will reduce to True (or False). Otherwise, the relation is maintained as an unevaluated Equality object. Use the ``simplify`` function on this object for more nontrivial evaluation of the equality relation. As usual, the keyword argument ``evaluate=False`` can be used to prevent any evaluation. Examples ======== >>> from sympy import Eq, simplify, exp, cos >>> from sympy.abc import x, y >>> Eq(y, x + x2) Eq(y, x2 + x) >>> Eq(2, 5) False >>> Eq(2, 5, evaluate=False) Eq(2, 5) >>> _.doit() False >>> Eq(exp(x), exp(x).rewrite(cos)) Eq(exp(x), sinh(x) + cosh(x)) >>> simplify(_) True See Also ======== sympy.logic.boolalg.Equivalent : for representing equality between two boolean expressions Notes ===== This class is not the same as the == operator. The == operator tests for exact structural equality between two expressions; this class compares expressions mathematically. If either object defines an `_eval_Eq` method, it can be used in place of the default algorithm. If `lhs._eval_Eq(rhs)` or `rhs._eval_Eq(lhs)` returns anything other than None, that return value will be substituted for the Equality. If None is returned by `_eval_Eq`, an Equality object will be created as usual. Since this object is already an expression, it does not respond to the method `as_expr` if one tries to create `x - y` from Eq(x, y). This can be done with the `rewrite(Add)` method. """ rel_op = '==' __slots__ = [] is_Equality = True def __new__(cls, lhs, rhs=0, options): from sympy.core.add import Add from sympy.core.logic import fuzzy_bool from sympy.core.expr import _n2 from sympy.simplify.simplify import clear_coefficients lhs = _sympify(lhs) rhs = _sympify(rhs) evaluate = options.pop('evaluate', global_evaluate[0]) if evaluate: # If one expression has an _eval_Eq, return its results. if hasattr(lhs, '_eval_Eq'): r = lhs._eval_Eq(rhs) if r is not None: return r if hasattr(rhs, '_eval_Eq'): r = rhs._eval_Eq(lhs) if r is not None: return r # If expressions have the same structure, they must be equal. if lhs == rhs: return S.true # e.g. True == True elif all(isinstance(i, BooleanAtom) for i in (rhs, lhs)): return S.false # True != False elif not (lhs.is_Symbol or rhs.is_Symbol) and ( isinstance(lhs, Boolean) != isinstance(rhs, Boolean)): return S.false # only Booleans can equal Booleans # check finiteness fin = L, R = [i.is_finite for i in (lhs, rhs)] if None not in fin: if L != R: return S.false if L is False: if lhs == -rhs: # Eq(oo, -oo) return S.false return S.true elif None in fin and False in fin: return Relational.__new__(cls, lhs, rhs, options) if all(isinstance(i, Expr) for i in (lhs, rhs)): # see if the difference evaluates dif = lhs - rhs z = dif.is_zero if z is not None: if z is False and dif.is_commutative: # issue 10728 return S.false if z: return S.true # evaluate numerically if possible n2 = _n2(lhs, rhs) if n2 is not None: return _sympify(n2 == 0) # see if the ratio evaluates n, d = dif.as_numer_denom() rv = None if n.is_zero: rv = d.is_nonzero elif n.is_finite: if d.is_infinite: rv = S.true elif n.is_zero is False: rv = d.is_infinite if rv is None: # if the condition that makes the denominator infinite does not # make the original expression True then False can be returned l, r = clear_coefficients(d, S.Infinity) args = [_.subs(l, r) for _ in (lhs, rhs)] if args != [lhs, rhs]: rv = fuzzy_bool(Eq(args)) if rv is True: rv = None elif any(a.is_infinite for a in Add.make_args(n)): # (inf or nan)/x != 0 rv = S.false if rv is not None: return _sympify(rv) return Relational.__new__(cls, lhs, rhs, options) @classmethod def _eval_relation(cls, lhs, rhs): return _sympify(lhs == rhs) def _eval_rewrite_as_Add(self, args, *kwargs): """return Eq(L, R) as L - R. To control the evaluation of the result set pass `evaluate=True` to give L - R; if `evaluate=None` then terms in L and R will not cancel but they will be listed in canonical order; otherwise non-canonical args will be returned. Examples ======== >>> from sympy import Eq, Add >>> from sympy.abc import b, x >>> eq = Eq(x + b, x - b) >>> eq.rewrite(Add) 2b >>> eq.rewrite(Add, evaluate=None).args (b, b, x, -x) >>> eq.rewrite(Add, evaluate=False).args (b, x, b, -x) """ L, R = args evaluate = kwargs.get('evaluate', True) if evaluate: # allow cancellation of args return L - R args = Add.make_args(L) + Add.make_args(-R) if evaluate is None: # no cancellation, but canonical return _unevaluated_Add(args) # no cancellation, not canonical return Add._from_args(args) @property def binary_symbols(self): if S.true in self.args or S.false in self.args: if self.lhs.is_Symbol: return set([self.lhs]) elif self.rhs.is_Symbol: return set([self.rhs]) return set() def _eval_simplify(self, ratio, measure, rational, inverse): from sympy.solvers.solveset import linear_coeffs # standard simplify e = super(Equality, self)._eval_simplify( ratio, measure, rational, inverse) if not isinstance(e, Equality): return e free = self.free_symbols if len(free) == 1: try: x = free.pop() m, b = linear_coeffs( e.rewrite(Add, evaluate=False), x) if m.is_zero is False: enew = e.func(x, -b/m) else: enew = e.func(mx, -b) if measure(enew) <= ratiomeasure(e): e = enew except ValueError: pass return e.canonical Eq = Equality class Unequality(Relational): """An unequal relation between two objects. Represents that two objects are not equal. If they can be shown to be definitively equal, this will reduce to False; if definitively unequal, this will reduce to True. Otherwise, the relation is maintained as an Unequality object. Examples ======== >>> from sympy import Ne >>> from sympy.abc import x, y >>> Ne(y, x+x2) Ne(y, x2 + x) See Also ======== Equality Notes ===== This class is not the same as the != operator. The != operator tests for exact structural equality between two expressions; this class compares expressions mathematically. This class is effectively the inverse of Equality. As such, it uses the same algorithms, including any available `_eval_Eq` methods. """ rel_op = '!=' __slots__ = [] def __new__(cls, lhs, rhs, options): lhs = _sympify(lhs) rhs = _sympify(rhs) evaluate = options.pop('evaluate', global_evaluate[0]) if evaluate: is_equal = Equality(lhs, rhs) if isinstance(is_equal, BooleanAtom): return ~is_equal return Relational.__new__(cls, lhs, rhs, options) @classmethod def _eval_relation(cls, lhs, rhs): return _sympify(lhs != rhs) @property def binary_symbols(self): if S.true in self.args or S.false in self.args: if self.lhs.is_Symbol: return set([self.lhs]) elif self.rhs.is_Symbol: return set([self.rhs]) return set() def _eval_simplify(self, ratio, measure, rational, inverse): # simplify as an equality eq = Equality(self.args)._eval_simplify( ratio, measure, rational, inverse) if isinstance(eq, Equality): # send back Ne with the new args return self.func(eq.args) return ~eq # result of Ne is ~Eq Ne = Unequality class _Inequality(Relational): """Internal base class for all Than types. Each subclass must implement _eval_relation to provide the method for comparing two real numbers. """ __slots__ = [] def __new__(cls, lhs, rhs, options): lhs = _sympify(lhs) rhs = _sympify(rhs) evaluate = options.pop('evaluate', global_evaluate[0]) if evaluate: # First we invoke the appropriate inequality method of `lhs` # (e.g., `lhs.__lt__`). That method will try to reduce to # boolean or raise an exception. It may keep calling # superclasses until it reaches `Expr` (e.g., `Expr.__lt__`). # In some cases, `Expr` will just invoke us again (if neither it # nor a subclass was able to reduce to boolean or raise an # exception). In that case, it must call us with # `evaluate=False` to prevent infinite recursion. r = cls._eval_relation(lhs, rhs) if r is not None: return r # Note: not sure r could be None, perhaps we never take this # path? In principle, could use this to shortcut out if a # class realizes the inequality cannot be evaluated further. # make a "non-evaluated" Expr for the inequality return Relational.__new__(cls, lhs, rhs, options) class _Greater(_Inequality): """Not intended for general use _Greater is only used so that GreaterThan and StrictGreaterThan may subclass it for the .gts and .lts properties. """ __slots__ = () @property def gts(self): return self._args[0] @property def lts(self): return self._args[1] class _Less(_Inequality): """Not intended for general use. _Less is only used so that LessThan and StrictLessThan may subclass it for the .gts and .lts properties. """ __slots__ = () @property def gts(self): return self._args[1] @property def lts(self): return self._args[0] class GreaterThan(_Greater): """Class representations of inequalities. Extended Summary ================ The ``Than`` classes represent inequal relationships, where the left-hand side is generally bigger or smaller than the right-hand side. For example, the GreaterThan class represents an inequal relationship where the left-hand side is at least as big as the right side, if not bigger. In mathematical notation: lhs >= rhs In total, there are four ``Than`` classes, to represent the four inequalities: +-----------------+--------+ \|Class Name \| Symbol \| +=================+========+ \|GreaterThan \| (>=) \| +-----------------+--------+ \|LessThan \| (<=) \| +-----------------+--------+ \|StrictGreaterThan\| (>) \| +-----------------+--------+ \|StrictLessThan \| (<) \| +-----------------+--------+ All classes take two arguments, lhs and rhs. +----------------------------+-----------------+ \|Signature Example \| Math equivalent \| +============================+=================+ \|GreaterThan(lhs, rhs) \| lhs >= rhs \| +----------------------------+-----------------+ \|LessThan(lhs, rhs) \| lhs <= rhs \| +----------------------------+-----------------+ \|StrictGreaterThan(lhs, rhs) \| lhs > rhs \| +----------------------------+-----------------+ \|StrictLessThan(lhs, rhs) \| lhs < rhs \| +----------------------------+-----------------+ In addition to the normal .lhs and .rhs of Relations, ``Than`` inequality objects also have the .lts and .gts properties, which represent the "less than side" and "greater than side" of the operator. Use of .lts and .gts in an algorithm rather than .lhs and .rhs as an assumption of inequality direction will make more explicit the intent of a certain section of code, and will make it similarly more robust to client code changes: >>> from sympy import GreaterThan, StrictGreaterThan >>> from sympy import LessThan, StrictLessThan >>> from sympy import And, Ge, Gt, Le, Lt, Rel, S >>> from sympy.abc import x, y, z >>> from sympy.core.relational import Relational >>> e = GreaterThan(x, 1) >>> e x >= 1 >>> '%s >= %s is the same as %s <= %s' % (e.gts, e.lts, e.lts, e.gts) 'x >= 1 is the same as 1 <= x' Examples ======== One generally does not instantiate these classes directly, but uses various convenience methods: >>> for f in [Ge, Gt, Le, Lt]: # convenience wrappers ... print(f(x, 2)) x >= 2 x > 2 x <= 2 x < 2 Another option is to use the Python inequality operators (>=, >, <=, <) directly. Their main advantage over the Ge, Gt, Le, and Lt counterparts, is that one can write a more "mathematical looking" statement rather than littering the math with oddball function calls. However there are certain (minor) caveats of which to be aware (search for 'gotcha', below). >>> x >= 2 x >= 2 >>> _ == Ge(x, 2) True However, it is also perfectly valid to instantiate a ``Than`` class less succinctly and less conveniently: >>> Rel(x, 1, ">") x > 1 >>> Relational(x, 1, ">") x > 1 >>> StrictGreaterThan(x, 1) x > 1 >>> GreaterThan(x, 1) x >= 1 >>> LessThan(x, 1) x <= 1 >>> StrictLessThan(x, 1) x < 1 Notes ===== There are a couple of "gotchas" to be aware of when using Python's operators. The first is that what your write is not always what you get: >>> 1 < x x > 1 Due to the order that Python parses a statement, it may not immediately find two objects comparable. When "1 < x" is evaluated, Python recognizes that the number 1 is a native number and that x is not. Because a native Python number does not know how to compare itself with a SymPy object Python will try the reflective operation, "x > 1" and that is the form that gets evaluated, hence returned. If the order of the statement is important (for visual output to the console, perhaps), one can work around this annoyance in a couple ways: (1) "sympify" the literal before comparison >>> S(1) < x 1 < x (2) use one of the wrappers or less succinct methods described above >>> Lt(1, x) 1 < x >>> Relational(1, x, "<") 1 < x The second gotcha involves writing equality tests between relationals when one or both sides of the test involve a literal relational: >>> e = x < 1; e x < 1 >>> e == e # neither side is a literal True >>> e == x < 1 # expecting True, too False >>> e != x < 1 # expecting False x < 1 >>> x < 1 != x < 1 # expecting False or the same thing as before Traceback (most recent call last): ... TypeError: cannot determine truth value of Relational The solution for this case is to wrap literal relationals in parentheses: >>> e == (x < 1) True >>> e != (x < 1) False >>> (x < 1) != (x < 1) False The third gotcha involves chained inequalities not involving '==' or '!='. Occasionally, one may be tempted to write: >>> e = x < y < z Traceback (most recent call last): ... TypeError: symbolic boolean expression has no truth value. Due to an implementation detail or decision of Python [1]_, there is no way for SymPy to create a chained inequality with that syntax so one must use And: >>> e = And(x < y, y < z) >>> type( e ) And >>> e (x < y) & (y < z) Although this can also be done with the '&' operator, it cannot be done with the 'and' operarator: >>> (x < y) & (y < z) (x < y) & (y < z) >>> (x < y) and (y < z) Traceback (most recent call last): ... TypeError: cannot determine truth value of Relational .. [1] This implementation detail is that Python provides no reliable method to determine that a chained inequality is being built. Chained comparison operators are evaluated pairwise, using "and" logic (see http://docs.python.org/2/reference/expressions.html#notin). This is done in an efficient way, so that each object being compared is only evaluated once and the comparison can short-circuit. For example, ``1 > 2 > 3`` is evaluated by Python as ``(1 > 2) and (2 > 3)``. The ``and`` operator coerces each side into a bool, returning the object itself when it short-circuits. The bool of the --Than operators will raise TypeError on purpose, because SymPy cannot determine the mathematical ordering of symbolic expressions. Thus, if we were to compute ``x > y > z``, with ``x``, ``y``, and ``z`` being Symbols, Python converts the statement (roughly) into these steps: (1) x > y > z (2) (x > y) and (y > z) (3) (GreaterThanObject) and (y > z) (4) (GreaterThanObject.__nonzero__()) and (y > z) (5) TypeError Because of the "and" added at step 2, the statement gets turned into a weak ternary statement, and the first object's __nonzero__ method will raise TypeError. Thus, creating a chained inequality is not possible. In Python, there is no way to override the ``and`` operator, or to control how it short circuits, so it is impossible to make something like ``x > y > z`` work. There was a PEP to change this, :pep:`335`, but it was officially closed in March, 2012. """ __slots__ = () rel_op = '>=' @classmethod def _eval_relation(cls, lhs, rhs): # We don't use the op symbol here: workaround issue #7951 return _sympify(lhs.__ge__(rhs)) Ge = GreaterThan class LessThan(_Less): __doc__ = GreaterThan.__doc__ __slots__ = () rel_op = '<=' @classmethod def _eval_relation(cls, lhs, rhs): # We don't use the op symbol here: workaround issue #7951 return _sympify(lhs.__le__(rhs)) Le = LessThan class StrictGreaterThan(_Greater): __doc__ = GreaterThan.__doc__ __slots__ = () rel_op = '>' @classmethod def _eval_relation(cls, lhs, rhs): # We don't use the op symbol here: workaround issue #7951 return _sympify(lhs.__gt__(rhs)) Gt = StrictGreaterThan class StrictLessThan(_Less): __doc__ = GreaterThan.__doc__ __slots__ = () rel_op = '<' @classmethod def _eval_relation(cls, lhs, rhs): # We don't use the op symbol here: workaround issue #7951 return _sympify(lhs.__lt__(rhs)) Lt = StrictLessThan # A class-specific (not object-specific) data item used for a minor speedup. It # is defined here, rather than directly in the class, because the classes that # it references have not been defined until now (e.g. StrictLessThan). Relational.ValidRelationOperator = { None: Equality, '==': Equality, 'eq': Equality, '!=': Unequality, '<>': Unequality, 'ne': Unequality, '>=': GreaterThan, 'ge': GreaterThan, '<=': LessThan, 'le': LessThan, '>': StrictGreaterThan, 'gt': StrictGreaterThan, '<': StrictLessThan, 'lt': StrictLessThan, }
3dc576bece2df886560b06ad40e8d6e815c1d3d541c6a49e3307b9b481025ee3	from __future__ import print_function, division import decimal import fractions import math import re as regex from .containers import Tuple from .sympify import converter, sympify, _sympify, SympifyError, _convert_numpy_types from .singleton import S, Singleton from .expr import Expr, AtomicExpr from .decorators import _sympifyit from .cache import cacheit, clear_cache from .logic import fuzzy_not from sympy.core.compatibility import ( as_int, integer_types, long, string_types, with_metaclass, HAS_GMPY, SYMPY_INTS, int_info) from sympy.core.cache import lru_cache import mpmath import mpmath.libmp as mlib from mpmath.libmp.backend import MPZ from mpmath.libmp import mpf_pow, mpf_pi, mpf_e, phi_fixed from mpmath.ctx_mp import mpnumeric from mpmath.libmp.libmpf import ( finf as _mpf_inf, fninf as _mpf_ninf, fnan as _mpf_nan, fzero as _mpf_zero, _normalize as mpf_normalize, prec_to_dps) from sympy.utilities.misc import debug, filldedent from .evaluate import global_evaluate from sympy.utilities.exceptions import SymPyDeprecationWarning rnd = mlib.round_nearest _LOG2 = math.log(2) def comp(z1, z2, tol=None): """Return a bool indicating whether the error between z1 and z2 is <= tol. If ``tol`` is None then True will be returned if there is a significant difference between the numbers: ``abs(z1 - z2)10p <= 1/2`` where ``p`` is the lower of the precisions of the values. A comparison of strings will be made if ``z1`` is a Number and a) ``z2`` is a string or b) ``tol`` is '' and ``z2`` is a Number. When ``tol`` is a nonzero value, if z2 is non-zero and ``\|z1\| > 1`` the error is normalized by ``\|z1\|``, so if you want to see if the absolute error between ``z1`` and ``z2`` is <= ``tol`` then call this as ``comp(z1 - z2, 0, tol)``. """ if type(z2) is str: if not isinstance(z1, Number): raise ValueError('when z2 is a str z1 must be a Number') return str(z1) == z2 if not z1: z1, z2 = z2, z1 if not z1: return True if not tol: if tol is None: if type(z2) is str and getattr(z1, 'is_Number', False): return str(z1) == z2 a, b = Float(z1), Float(z2) return int(abs(a - b)10*prec_to_dps( min(a._prec, b._prec)))2 <= 1 elif all(getattr(i, 'is_Number', False) for i in (z1, z2)): return z1._prec == z2._prec and str(z1) == str(z2) raise ValueError('exact comparison requires two Numbers') diff = abs(z1 - z2) az1 = abs(z1) if z2 and az1 > 1: return diff/az1 <= tol else: return diff <= tol def mpf_norm(mpf, prec): """Return the mpf tuple normalized appropriately for the indicated precision after doing a check to see if zero should be returned or not when the mantissa is 0. ``mpf_normlize`` always assumes that this is zero, but it may not be since the mantissa for mpf's values "+inf", "-inf" and "nan" have a mantissa of zero, too. Note: this is not intended to validate a given mpf tuple, so sending mpf tuples that were not created by mpmath may produce bad results. This is only a wrapper to ``mpf_normalize`` which provides the check for non- zero mpfs that have a 0 for the mantissa. """ sign, man, expt, bc = mpf if not man: # hack for mpf_normalize which does not do this; # it assumes that if man is zero the result is 0 # (see issue 6639) if not bc: return _mpf_zero else: # don't change anything; this should already # be a well formed mpf tuple return mpf # Necessary if mpmath is using the gmpy backend from mpmath.libmp.backend import MPZ rv = mpf_normalize(sign, MPZ(man), expt, bc, prec, rnd) return rv # TODO: we should use the warnings module _errdict = {"divide": False} def seterr(divide=False): """ Should sympy raise an exception on 0/0 or return a nan? divide == True .... raise an exception divide == False ... return nan """ if _errdict["divide"] != divide: clear_cache() _errdict["divide"] = divide def _as_integer_ratio(p): neg_pow, man, expt, bc = getattr(p, '_mpf_', mpmath.mpf(p)._mpf_) p = [1, -1][neg_pow % 2]man if expt < 0: q = 2-expt else: q = 1 p = 2expt return int(p), int(q) def _decimal_to_Rational_prec(dec): """Convert an ordinary decimal instance to a Rational.""" if not dec.is_finite(): raise TypeError("dec must be finite, got %s." % dec) s, d, e = dec.as_tuple() prec = len(d) if e >= 0: # it's an integer rv = Integer(int(dec)) else: s = (-1)s d = sum([di10i for i, di in enumerate(reversed(d))]) rv = Rational(sd, 10*-e) return rv, prec def _literal_float(f): """Return True if n can be interpreted as a floating point number.""" pat = r"[-+]?((\d\.\d+)\|(\d+\.?))(eE[-+]?\d+)?" return bool(regex.match(pat, f)) # (a,b) -> gcd(a,b) # TODO caching with decorator, but not to degrade performance @lru_cache(1024) def igcd(args): """Computes nonnegative integer greatest common divisor. The algorithm is based on the well known Euclid's algorithm. To improve speed, igcd() has its own caching mechanism implemented. Examples ======== >>> from sympy.core.numbers import igcd >>> igcd(2, 4) 2 >>> igcd(5, 10, 15) 5 """ if len(args) < 2: raise TypeError( 'igcd() takes at least 2 arguments (%s given)' % len(args)) args_temp = [abs(as_int(i)) for i in args] if 1 in args_temp: return 1 a = args_temp.pop() for b in args_temp: a = igcd2(a, b) if b else a return a try: from math import gcd as igcd2 except ImportError: def igcd2(a, b): """Compute gcd of two Python integers a and b.""" if (a.bit_length() > BIGBITS and b.bit_length() > BIGBITS): return igcd_lehmer(a, b) a, b = abs(a), abs(b) while b: a, b = b, a % b return a # Use Lehmer's algorithm only for very large numbers. # The limit could be different on Python 2.7 and 3.x. # If so, then this could be defined in compatibility.py. BIGBITS = 5000 def igcd_lehmer(a, b): """Computes greatest common divisor of two integers. Euclid's algorithm for the computation of the greatest common divisor gcd(a, b) of two (positive) integers a and b is based on the division identity a = qb + r, where the quotient q and the remainder r are integers and 0 <= r < b. Then each common divisor of a and b divides r, and it follows that gcd(a, b) == gcd(b, r). The algorithm works by constructing the sequence r0, r1, r2, ..., where r0 = a, r1 = b, and each rn is the remainder from the division of the two preceding elements. In Python, q = a // b and r = a % b are obtained by the floor division and the remainder operations, respectively. These are the most expensive arithmetic operations, especially for large a and b. Lehmer's algorithm is based on the observation that the quotients qn = r(n-1) // rn are in general small integers even when a and b are very large. Hence the quotients can be usually determined from a relatively small number of most significant bits. The efficiency of the algorithm is further enhanced by not computing each long remainder in Euclid's sequence. The remainders are linear combinations of a and b with integer coefficients derived from the quotients. The coefficients can be computed as far as the quotients can be determined from the chosen most significant parts of a and b. Only then a new pair of consecutive remainders is computed and the algorithm starts anew with this pair. References ========== .. [1] https://en.wikipedia.org/wiki/Lehmer%27s_GCD_algorithm """ a, b = abs(as_int(a)), abs(as_int(b)) if a < b: a, b = b, a # The algorithm works by using one or two digit division # whenever possible. The outer loop will replace the # pair (a, b) with a pair of shorter consecutive elements # of the Euclidean gcd sequence until a and b # fit into two Python (long) int digits. nbits = 2int_info.bits_per_digit while a.bit_length() > nbits and b != 0: # Quotients are mostly small integers that can # be determined from most significant bits. n = a.bit_length() - nbits x, y = int(a >> n), int(b >> n) # most significant bits # Elements of the Euclidean gcd sequence are linear # combinations of a and b with integer coefficients. # Compute the coefficients of consecutive pairs # a' = Aa + Bb, b' = Ca + Db # using small integer arithmetic as far as possible. A, B, C, D = 1, 0, 0, 1 # initial values while True: # The coefficients alternate in sign while looping. # The inner loop combines two steps to keep track # of the signs. # At this point we have # A > 0, B <= 0, C <= 0, D > 0, # x' = x + B <= x < x" = x + A, # y' = y + C <= y < y" = y + D, # and # x'N <= a' < x"N, y'N <= b' < y"N, # where N = 2n. # Now, if y' > 0, and x"//y' and x'//y" agree, # then their common value is equal to q = a'//b'. # In addition, # x'%y" = x' - qy" < x" - qy' = x"%y', # and # (x'%y")N < a'%b' < (x"%y')N. # On the other hand, we also have x//y == q, # and therefore # x'%y" = x + B - q(y + D) = x%y + B', # x"%y' = x + A - q(y + C) = x%y + A', # where # B' = B - qD < 0, A' = A - qC > 0. if y + C <= 0: break q = (x + A) // (y + C) # Now x'//y" <= q, and equality holds if # x' - qy" = (x - qy) + (B - qD) >= 0. # This is a minor optimization to avoid division. x_qy, B_qD = x - qy, B - qD if x_qy + B_qD < 0: break # Next step in the Euclidean sequence. x, y = y, x_qy A, B, C, D = C, D, A - qC, B_qD # At this point the signs of the coefficients # change and their roles are interchanged. # A <= 0, B > 0, C > 0, D < 0, # x' = x + A <= x < x" = x + B, # y' = y + D < y < y" = y + C. if y + D <= 0: break q = (x + B) // (y + D) x_qy, A_qC = x - qy, A - qC if x_qy + A_qC < 0: break x, y = y, x_qy A, B, C, D = C, D, A_qC, B - qD # Now the conditions on top of the loop # are again satisfied. # A > 0, B < 0, C < 0, D > 0. if B == 0: # This can only happen when y == 0 in the beginning # and the inner loop does nothing. # Long division is forced. a, b = b, a % b continue # Compute new long arguments using the coefficients. a, b = Aa + Bb, Ca + Db # Small divisors. Finish with the standard algorithm. while b: a, b = b, a % b return a def ilcm(args): """Computes integer least common multiple. Examples ======== >>> from sympy.core.numbers import ilcm >>> ilcm(5, 10) 10 >>> ilcm(7, 3) 21 >>> ilcm(5, 10, 15) 30 """ if len(args) < 2: raise TypeError( 'ilcm() takes at least 2 arguments (%s given)' % len(args)) if 0 in args: return 0 a = args[0] for b in args[1:]: a = a // igcd(a, b) b # since gcd(a,b) \| a return a def igcdex(a, b): """Returns x, y, g such that g = xa + yb = gcd(a, b). >>> from sympy.core.numbers import igcdex >>> igcdex(2, 3) (-1, 1, 1) >>> igcdex(10, 12) (-1, 1, 2) >>> x, y, g = igcdex(100, 2004) >>> x, y, g (-20, 1, 4) >>> x100 + y2004 4 """ if (not a) and (not b): return (0, 1, 0) if not a: return (0, b//abs(b), abs(b)) if not b: return (a//abs(a), 0, abs(a)) if a < 0: a, x_sign = -a, -1 else: x_sign = 1 if b < 0: b, y_sign = -b, -1 else: y_sign = 1 x, y, r, s = 1, 0, 0, 1 while b: (c, q) = (a % b, a // b) (a, b, r, s, x, y) = (b, c, x - qr, y - qs, r, s) return (xx_sign, yy_sign, a) def mod_inverse(a, m): """ Return the number c such that, (a * c) = 1 (mod m) where c has the same sign as m. If no such value exists, a ValueError is raised. Examples ======== >>> from sympy import S >>> from sympy.core.numbers import mod_inverse Suppose we wish to find multiplicative inverse x of 3 modulo 11. This is the same as finding x such that 3 * x = 1 (mod 11). One value of x that satisfies this congruence is 4. Because 3 * 4 = 12 and 12 = 1 (mod 11). This is the value return by mod_inverse: >>> mod_inverse(3, 11) 4 >>> mod_inverse(-3, 11) 7 When there is a common factor between the numerators of ``a`` and ``m`` the inverse does not exist: >>> mod_inverse(2, 4) Traceback (most recent call last): ... ValueError: inverse of 2 mod 4 does not exist >>> mod_inverse(S(2)/7, S(5)/2) 7/2 References ========== - https://en.wikipedia.org/wiki/Modular_multiplicative_inverse - https://en.wikipedia.org/wiki/Extended_Euclidean_algorithm """ c = None try: a, m = as_int(a), as_int(m) if m != 1 and m != -1: x, y, g = igcdex(a, m) if g == 1: c = x % m except ValueError: a, m = sympify(a), sympify(m) if not (a.is_number and m.is_number): raise TypeError(filldedent(''' Expected numbers for arguments; symbolic `mod_inverse` is not implemented but symbolic expressions can be handled with the similar function, sympy.polys.polytools.invert''')) big = (m > 1) if not (big is S.true or big is S.false): raise ValueError('m > 1 did not evaluate; try to simplify %s' % m) elif big: c = 1/a if c is None: raise ValueError('inverse of %s (mod %s) does not exist' % (a, m)) return c class Number(AtomicExpr): """Represents atomic numbers in SymPy. Floating point numbers are represented by the Float class. Rational numbers (of any size) are represented by the Rational class. Integer numbers (of any size) are represented by the Integer class. Float and Rational are subclasses of Number; Integer is a subclass of Rational. For example, ``2/3`` is represented as ``Rational(2, 3)`` which is a different object from the floating point number obtained with Python division ``2/3``. Even for numbers that are exactly represented in binary, there is a difference between how two forms, such as ``Rational(1, 2)`` and ``Float(0.5)``, are used in SymPy. The rational form is to be preferred in symbolic computations. Other kinds of numbers, such as algebraic numbers ``sqrt(2)`` or complex numbers ``3 + 4I``, are not instances of Number class as they are not atomic. See Also ======== Float, Integer, Rational """ is_commutative = True is_number = True is_Number = True __slots__ = [] # Used to make max(x._prec, y._prec) return x._prec when only x is a float _prec = -1 def __new__(cls, obj): if len(obj) == 1: obj = obj[0] if isinstance(obj, Number): return obj if isinstance(obj, SYMPY_INTS): return Integer(obj) if isinstance(obj, tuple) and len(obj) == 2: return Rational(obj) if isinstance(obj, (float, mpmath.mpf, decimal.Decimal)): return Float(obj) if isinstance(obj, string_types): val = sympify(obj) if isinstance(val, Number): return val else: raise ValueError('String "%s" does not denote a Number' % obj) msg = "expected str\|int\|long\|float\|Decimal\|Number object but got %r" raise TypeError(msg % type(obj).__name__) def invert(self, other, gens, *args): from sympy.polys.polytools import invert if getattr(other, 'is_number', True): return mod_inverse(self, other) return invert(self, other, gens, *args) def __divmod__(self, other): from .containers import Tuple try: other = Number(other) except TypeError: msg = "unsupported operand type(s) for divmod(): '%s' and '%s'" raise TypeError(msg % (type(self).__name__, type(other).__name__)) if not other: raise ZeroDivisionError('modulo by zero') if self.is_Integer and other.is_Integer: return Tuple(divmod(self.p, other.p)) else: rat = self/other w = int(rat) if rat > 0 else int(rat) - 1 r = self - otherw return Tuple(w, r) def __rdivmod__(self, other): try: other = Number(other) except TypeError: msg = "unsupported operand type(s) for divmod(): '%s' and '%s'" raise TypeError(msg % (type(other).__name__, type(self).__name__)) return divmod(other, self) def __round__(self, args): return round(float(self), args) def _as_mpf_val(self, prec): """Evaluation of mpf tuple accurate to at least prec bits.""" raise NotImplementedError('%s needs ._as_mpf_val() method' % (self.__class__.__name__)) def _eval_evalf(self, prec): return Float._new(self._as_mpf_val(prec), prec) def _as_mpf_op(self, prec): prec = max(prec, self._prec) return self._as_mpf_val(prec), prec def __float__(self): return mlib.to_float(self._as_mpf_val(53)) def floor(self): raise NotImplementedError('%s needs .floor() method' % (self.__class__.__name__)) def ceiling(self): raise NotImplementedError('%s needs .ceiling() method' % (self.__class__.__name__)) def _eval_conjugate(self): return self def _eval_order(self, symbols): from sympy import Order # Order(5, x, y) -> Order(1,x,y) return Order(S.One, symbols) def _eval_subs(self, old, new): if old == -self: return -new return self # there is no other possibility def _eval_is_finite(self): return True @classmethod def class_key(cls): return 1, 0, 'Number' @cacheit def sort_key(self, order=None): return self.class_key(), (0, ()), (), self @_sympifyit('other', NotImplemented) def __add__(self, other): if isinstance(other, Number) and global_evaluate[0]: if other is S.NaN: return S.NaN elif other is S.Infinity: return S.Infinity elif other is S.NegativeInfinity: return S.NegativeInfinity return AtomicExpr.__add__(self, other) @_sympifyit('other', NotImplemented) def __sub__(self, other): if isinstance(other, Number) and global_evaluate[0]: if other is S.NaN: return S.NaN elif other is S.Infinity: return S.NegativeInfinity elif other is S.NegativeInfinity: return S.Infinity return AtomicExpr.__sub__(self, other) @_sympifyit('other', NotImplemented) def __mul__(self, other): if isinstance(other, Number) and global_evaluate[0]: if other is S.NaN: return S.NaN elif other is S.Infinity: if self.is_zero: return S.NaN elif self.is_positive: return S.Infinity else: return S.NegativeInfinity elif other is S.NegativeInfinity: if self.is_zero: return S.NaN elif self.is_positive: return S.NegativeInfinity else: return S.Infinity elif isinstance(other, Tuple): return NotImplemented return AtomicExpr.__mul__(self, other) @_sympifyit('other', NotImplemented) def __div__(self, other): if isinstance(other, Number) and global_evaluate[0]: if other is S.NaN: return S.NaN elif other is S.Infinity or other is S.NegativeInfinity: return S.Zero return AtomicExpr.__div__(self, other) __truediv__ = __div__ def __eq__(self, other): raise NotImplementedError('%s needs .__eq__() method' % (self.__class__.__name__)) def __ne__(self, other): raise NotImplementedError('%s needs .__ne__() method' % (self.__class__.__name__)) def __lt__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s < %s" % (self, other)) raise NotImplementedError('%s needs .__lt__() method' % (self.__class__.__name__)) def __le__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s <= %s" % (self, other)) raise NotImplementedError('%s needs .__le__() method' % (self.__class__.__name__)) def __gt__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s > %s" % (self, other)) return _sympify(other).__lt__(self) def __ge__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s >= %s" % (self, other)) return _sympify(other).__le__(self) def __hash__(self): return super(Number, self).__hash__() def is_constant(self, wrt, *flags): return True def as_coeff_mul(self, deps, *kwargs): # a -> ct if self.is_Rational or not kwargs.pop('rational', True): return self, tuple() elif self.is_negative: return S.NegativeOne, (-self,) return S.One, (self,) def as_coeff_add(self, deps): # a -> c + t if self.is_Rational: return self, tuple() return S.Zero, (self,) def as_coeff_Mul(self, rational=False): """Efficiently extract the coefficient of a product. """ if rational and not self.is_Rational: return S.One, self return (self, S.One) if self else (S.One, self) def as_coeff_Add(self, rational=False): """Efficiently extract the coefficient of a summation. """ if not rational: return self, S.Zero return S.Zero, self def gcd(self, other): """Compute GCD of `self` and `other`. """ from sympy.polys import gcd return gcd(self, other) def lcm(self, other): """Compute LCM of `self` and `other`. """ from sympy.polys import lcm return lcm(self, other) def cofactors(self, other): """Compute GCD and cofactors of `self` and `other`. """ from sympy.polys import cofactors return cofactors(self, other) class Float(Number): """Represent a floating-point number of arbitrary precision. Examples ======== >>> from sympy import Float >>> Float(3.5) 3.50000000000000 >>> Float(3) 3.00000000000000 Creating Floats from strings (and Python ``int`` and ``long`` types) will give a minimum precision of 15 digits, but the precision will automatically increase to capture all digits entered. >>> Float(1) 1.00000000000000 >>> Float(1020) 100000000000000000000. >>> Float('1e20') 100000000000000000000. However, floating-point* numbers (Python ``float`` types) retain only 15 digits of precision: >>> Float(1e20) 1.00000000000000e+20 >>> Float(1.23456789123456789) 1.23456789123457 It may be preferable to enter high-precision decimal numbers as strings: Float('1.23456789123456789') 1.23456789123456789 The desired number of digits can also be specified: >>> Float('1e-3', 3) 0.00100 >>> Float(100, 4) 100.0 Float can automatically count significant figures if a null string is sent for the precision; space are also allowed in the string. (Auto- counting is only allowed for strings, ints and longs). >>> Float('123 456 789 . 123 456', '') 123456789.123456 >>> Float('12e-3', '') 0.012 >>> Float(3, '') 3. If a number is written in scientific notation, only the digits before the exponent are considered significant if a decimal appears, otherwise the "e" signifies only how to move the decimal: >>> Float('60.e2', '') # 2 digits significant 6.0e+3 >>> Float('60e2', '') # 4 digits significant 6000. >>> Float('600e-2', '') # 3 digits significant 6.00 Notes ===== Floats are inexact by their nature unless their value is a binary-exact value. >>> approx, exact = Float(.1, 1), Float(.125, 1) For calculation purposes, evalf needs to be able to change the precision but this will not increase the accuracy of the inexact value. The following is the most accurate 5-digit approximation of a value of 0.1 that had only 1 digit of precision: >>> approx.evalf(5) 0.099609 By contrast, 0.125 is exact in binary (as it is in base 10) and so it can be passed to Float or evalf to obtain an arbitrary precision with matching accuracy: >>> Float(exact, 5) 0.12500 >>> exact.evalf(20) 0.12500000000000000000 Trying to make a high-precision Float from a float is not disallowed, but one must keep in mind that the underlying float (not the apparent decimal value) is being obtained with high precision. For example, 0.3 does not have a finite binary representation. The closest rational is the fraction 5404319552844595/254. So if you try to obtain a Float of 0.3 to 20 digits of precision you will not see the same thing as 0.3 followed by 19 zeros: >>> Float(0.3, 20) 0.29999999999999998890 If you want a 20-digit value of the decimal 0.3 (not the floating point approximation of 0.3) you should send the 0.3 as a string. The underlying representation is still binary but a higher precision than Python's float is used: >>> Float('0.3', 20) 0.30000000000000000000 Although you can increase the precision of an existing Float using Float it will not increase the accuracy -- the underlying value is not changed: >>> def show(f): # binary rep of Float ... from sympy import Mul, Pow ... s, m, e, b = f._mpf_ ... v = Mul(int(m), Pow(2, int(e), evaluate=False), evaluate=False) ... print('%s at prec=%s' % (v, f._prec)) ... >>> t = Float('0.3', 3) >>> show(t) 4915/214 at prec=13 >>> show(Float(t, 20)) # higher prec, not higher accuracy 4915/214 at prec=70 >>> show(Float(t, 2)) # lower prec 307/210 at prec=10 The same thing happens when evalf is used on a Float: >>> show(t.evalf(20)) 4915/214 at prec=70 >>> show(t.evalf(2)) 307/210 at prec=10 Finally, Floats can be instantiated with an mpf tuple (n, c, p) to produce the number (-1)*nc2p: >>> n, c, p = 1, 5, 0 >>> (-1)nc2p -5 >>> Float((1, 5, 0)) -5.00000000000000 An actual mpf tuple also contains the number of bits in c as the last element of the tuple: >>> _._mpf_ (1, 5, 0, 3) This is not needed for instantiation and is not the same thing as the precision. The mpf tuple and the precision are two separate quantities that Float tracks. """ __slots__ = ['_mpf_', '_prec'] # A Float represents many real numbers, # both rational and irrational. is_rational = None is_irrational = None is_number = True is_real = True is_Float = True def __new__(cls, num, dps=None, prec=None, precision=None): if prec is not None: SymPyDeprecationWarning( feature="Using 'prec=XX' to denote decimal precision", useinstead="'dps=XX' for decimal precision and 'precision=XX' "\ "for binary precision", issue=12820, deprecated_since_version="1.1").warn() dps = prec del prec # avoid using this deprecated kwarg if dps is not None and precision is not None: raise ValueError('Both decimal and binary precision supplied. ' 'Supply only one. ') if isinstance(num, string_types): num = num.replace(' ', '') if num.startswith('.') and len(num) > 1: num = '0' + num elif num.startswith('-.') and len(num) > 2: num = '-0.' + num[2:] elif isinstance(num, float) and num == 0: num = '0' elif isinstance(num, (SYMPY_INTS, Integer)): num = str(num) # faster than mlib.from_int elif num is S.Infinity: num = '+inf' elif num is S.NegativeInfinity: num = '-inf' elif type(num).__module__ == 'numpy': # support for numpy datatypes num = _convert_numpy_types(num) elif isinstance(num, mpmath.mpf): if precision is None: if dps is None: precision = num.context.prec num = num._mpf_ if dps is None and precision is None: dps = 15 if isinstance(num, Float): return num if isinstance(num, string_types) and _literal_float(num): try: Num = decimal.Decimal(num) except decimal.InvalidOperation: pass else: isint = '.' not in num num, dps = _decimal_to_Rational_prec(Num) if num.is_Integer and isint: dps = max(dps, len(str(num).lstrip('-'))) dps = max(15, dps) precision = mlib.libmpf.dps_to_prec(dps) elif precision == '' and dps is None or precision is None and dps == '': if not isinstance(num, string_types): raise ValueError('The null string can only be used when ' 'the number to Float is passed as a string or an integer.') ok = None if _literal_float(num): try: Num = decimal.Decimal(num) except decimal.InvalidOperation: pass else: isint = '.' not in num num, dps = _decimal_to_Rational_prec(Num) if num.is_Integer and isint: dps = max(dps, len(str(num).lstrip('-'))) precision = mlib.libmpf.dps_to_prec(dps) ok = True if ok is None: raise ValueError('string-float not recognized: %s' % num) # decimal precision(dps) is set and maybe binary precision(precision) # as well.From here on binary precision is used to compute the Float. # Hence, if supplied use binary precision else translate from decimal # precision. if precision is None or precision == '': precision = mlib.libmpf.dps_to_prec(dps) precision = int(precision) if isinstance(num, float): _mpf_ = mlib.from_float(num, precision, rnd) elif isinstance(num, string_types): _mpf_ = mlib.from_str(num, precision, rnd) elif isinstance(num, decimal.Decimal): if num.is_finite(): _mpf_ = mlib.from_str(str(num), precision, rnd) elif num.is_nan(): _mpf_ = _mpf_nan elif num.is_infinite(): if num > 0: _mpf_ = _mpf_inf else: _mpf_ = _mpf_ninf else: raise ValueError("unexpected decimal value %s" % str(num)) elif isinstance(num, tuple) and len(num) in (3, 4): if type(num[1]) is str: # it's a hexadecimal (coming from a pickled object) # assume that it is in standard form num = list(num) # If we're loading an object pickled in Python 2 into # Python 3, we may need to strip a tailing 'L' because # of a shim for int on Python 3, see issue #13470. if num[1].endswith('L'): num[1] = num[1][:-1] num[1] = MPZ(num[1], 16) _mpf_ = tuple(num) else: if len(num) == 4: # handle normalization hack return Float._new(num, precision) else: return (S.NegativeOnenum[0]num[1]S(2)num[2]).evalf(precision) else: try: _mpf_ = num._as_mpf_val(precision) except (NotImplementedError, AttributeError): _mpf_ = mpmath.mpf(num, prec=precision)._mpf_ # special cases if _mpf_ == _mpf_zero: pass # we want a Float elif _mpf_ == _mpf_nan: return S.NaN obj = Expr.__new__(cls) obj._mpf_ = _mpf_ obj._prec = precision return obj @classmethod def _new(cls, _mpf_, _prec): # special cases if _mpf_ == _mpf_zero: return S.Zero # XXX this is different from Float which gives 0.0 elif _mpf_ == _mpf_nan: return S.NaN obj = Expr.__new__(cls) obj._mpf_ = mpf_norm(_mpf_, _prec) # XXX: Should this be obj._prec = obj._mpf_[3]? obj._prec = _prec return obj # mpz can't be pickled def __getnewargs__(self): return (mlib.to_pickable(self._mpf_),) def __getstate__(self): return {'_prec': self._prec} def _hashable_content(self): return (self._mpf_, self._prec) def floor(self): return Integer(int(mlib.to_int( mlib.mpf_floor(self._mpf_, self._prec)))) def ceiling(self): return Integer(int(mlib.to_int( mlib.mpf_ceil(self._mpf_, self._prec)))) @property def num(self): return mpmath.mpf(self._mpf_) def _as_mpf_val(self, prec): rv = mpf_norm(self._mpf_, prec) if rv != self._mpf_ and self._prec == prec: debug(self._mpf_, rv) return rv def _as_mpf_op(self, prec): return self._mpf_, max(prec, self._prec) def _eval_is_finite(self): if self._mpf_ in (_mpf_inf, _mpf_ninf): return False return True def _eval_is_infinite(self): if self._mpf_ in (_mpf_inf, _mpf_ninf): return True return False def _eval_is_integer(self): return self._mpf_ == _mpf_zero def _eval_is_negative(self): if self._mpf_ == _mpf_ninf: return True if self._mpf_ == _mpf_inf: return False return self.num < 0 def _eval_is_positive(self): if self._mpf_ == _mpf_inf: return True if self._mpf_ == _mpf_ninf: return False return self.num > 0 def _eval_is_zero(self): return self._mpf_ == _mpf_zero def __nonzero__(self): return self._mpf_ != _mpf_zero __bool__ = __nonzero__ def __neg__(self): return Float._new(mlib.mpf_neg(self._mpf_), self._prec) @_sympifyit('other', NotImplemented) def __add__(self, other): if isinstance(other, Number) and global_evaluate[0]: rhs, prec = other._as_mpf_op(self._prec) return Float._new(mlib.mpf_add(self._mpf_, rhs, prec, rnd), prec) return Number.__add__(self, other) @_sympifyit('other', NotImplemented) def __sub__(self, other): if isinstance(other, Number) and global_evaluate[0]: rhs, prec = other._as_mpf_op(self._prec) return Float._new(mlib.mpf_sub(self._mpf_, rhs, prec, rnd), prec) return Number.__sub__(self, other) @_sympifyit('other', NotImplemented) def __mul__(self, other): if isinstance(other, Number) and global_evaluate[0]: rhs, prec = other._as_mpf_op(self._prec) return Float._new(mlib.mpf_mul(self._mpf_, rhs, prec, rnd), prec) return Number.__mul__(self, other) @_sympifyit('other', NotImplemented) def __div__(self, other): if isinstance(other, Number) and other != 0 and global_evaluate[0]: rhs, prec = other._as_mpf_op(self._prec) return Float._new(mlib.mpf_div(self._mpf_, rhs, prec, rnd), prec) return Number.__div__(self, other) __truediv__ = __div__ @_sympifyit('other', NotImplemented) def __mod__(self, other): if isinstance(other, Rational) and other.q != 1 and global_evaluate[0]: # calculate mod with Rationals, then* round the result return Float(Rational.__mod__(Rational(self), other), precision=self._prec) if isinstance(other, Float) and global_evaluate[0]: r = self/other if r == int(r): return Float(0, precision=max(self._prec, other._prec)) if isinstance(other, Number) and global_evaluate[0]: rhs, prec = other._as_mpf_op(self._prec) return Float._new(mlib.mpf_mod(self._mpf_, rhs, prec, rnd), prec) return Number.__mod__(self, other) @_sympifyit('other', NotImplemented) def __rmod__(self, other): if isinstance(other, Float) and global_evaluate[0]: return other.__mod__(self) if isinstance(other, Number) and global_evaluate[0]: rhs, prec = other._as_mpf_op(self._prec) return Float._new(mlib.mpf_mod(rhs, self._mpf_, prec, rnd), prec) return Number.__rmod__(self, other) def _eval_power(self, expt): """ expt is symbolic object but not equal to 0, 1 (-p)*r -> exp(rlog(-p)) -> exp(r(log(p) + IPi)) -> -> p*r(sin(Pir) + cos(Pir)I) """ if self == 0: if expt.is_positive: return S.Zero if expt.is_negative: return Float('inf') if isinstance(expt, Number): if isinstance(expt, Integer): prec = self._prec return Float._new( mlib.mpf_pow_int(self._mpf_, expt.p, prec, rnd), prec) elif isinstance(expt, Rational) and \ expt.p == 1 and expt.q % 2 and self.is_negative: return Pow(S.NegativeOne, expt, evaluate=False)( -self)._eval_power(expt) expt, prec = expt._as_mpf_op(self._prec) mpfself = self._mpf_ try: y = mpf_pow(mpfself, expt, prec, rnd) return Float._new(y, prec) except mlib.ComplexResult: re, im = mlib.mpc_pow( (mpfself, _mpf_zero), (expt, _mpf_zero), prec, rnd) return Float._new(re, prec) + \ Float._new(im, prec)S.ImaginaryUnit def __abs__(self): return Float._new(mlib.mpf_abs(self._mpf_), self._prec) def __int__(self): if self._mpf_ == _mpf_zero: return 0 return int(mlib.to_int(self._mpf_)) # uses round_fast = round_down __long__ = __int__ def __eq__(self, other): if isinstance(other, float): # coerce to Float at same precision o = Float(other) try: ompf = o._as_mpf_val(self._prec) except ValueError: return False return bool(mlib.mpf_eq(self._mpf_, ompf)) try: other = _sympify(other) except SympifyError: return NotImplemented if other.is_NumberSymbol: if other.is_irrational: return False return other.__eq__(self) if other.is_Float: return bool(mlib.mpf_eq(self._mpf_, other._mpf_)) if other.is_Number: # numbers should compare at the same precision; # all _as_mpf_val routines should be sure to abide # by the request to change the prec if necessary; if # they don't, the equality test will fail since it compares # the mpf tuples ompf = other._as_mpf_val(self._prec) return bool(mlib.mpf_eq(self._mpf_, ompf)) return False # Float != non-Number def __ne__(self, other): return not self == other def __gt__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s > %s" % (self, other)) if other.is_NumberSymbol: return other.__lt__(self) if other.is_Rational and not other.is_Integer: self = other.q other = _sympify(other.p) elif other.is_comparable: other = other.evalf() if other.is_Number and other is not S.NaN: return _sympify(bool( mlib.mpf_gt(self._mpf_, other._as_mpf_val(self._prec)))) return Expr.__gt__(self, other) def __ge__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s >= %s" % (self, other)) if other.is_NumberSymbol: return other.__le__(self) if other.is_Rational and not other.is_Integer: self = other.q other = _sympify(other.p) elif other.is_comparable: other = other.evalf() if other.is_Number and other is not S.NaN: return _sympify(bool( mlib.mpf_ge(self._mpf_, other._as_mpf_val(self._prec)))) return Expr.__ge__(self, other) def __lt__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s < %s" % (self, other)) if other.is_NumberSymbol: return other.__gt__(self) if other.is_Rational and not other.is_Integer: self = other.q other = _sympify(other.p) elif other.is_comparable: other = other.evalf() if other.is_Number and other is not S.NaN: return _sympify(bool( mlib.mpf_lt(self._mpf_, other._as_mpf_val(self._prec)))) return Expr.__lt__(self, other) def __le__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s <= %s" % (self, other)) if other.is_NumberSymbol: return other.__ge__(self) if other.is_Rational and not other.is_Integer: self = other.q other = _sympify(other.p) elif other.is_comparable: other = other.evalf() if other.is_Number and other is not S.NaN: return _sympify(bool( mlib.mpf_le(self._mpf_, other._as_mpf_val(self._prec)))) return Expr.__le__(self, other) def __hash__(self): return super(Float, self).__hash__() def epsilon_eq(self, other, epsilon="1e-15"): return abs(self - other) < Float(epsilon) def _sage_(self): import sage.all as sage return sage.RealNumber(str(self)) def __format__(self, format_spec): return format(decimal.Decimal(str(self)), format_spec) # Add sympify converters converter[float] = converter[decimal.Decimal] = Float # this is here to work nicely in Sage RealNumber = Float class Rational(Number): """Represents rational numbers (p/q) of any size. Examples ======== >>> from sympy import Rational, nsimplify, S, pi >>> Rational(1, 2) 1/2 Rational is unprejudiced in accepting input. If a float is passed, the underlying value of the binary representation will be returned: >>> Rational(.5) 1/2 >>> Rational(.2) 3602879701896397/18014398509481984 If the simpler representation of the float is desired then consider limiting the denominator to the desired value or convert the float to a string (which is roughly equivalent to limiting the denominator to 1012): >>> Rational(str(.2)) 1/5 >>> Rational(.2).limit_denominator(1012) 1/5 An arbitrarily precise Rational is obtained when a string literal is passed: >>> Rational("1.23") 123/100 >>> Rational('1e-2') 1/100 >>> Rational(".1") 1/10 >>> Rational('1e-2/3.2') 1/320 The conversion of other types of strings can be handled by the sympify() function, and conversion of floats to expressions or simple fractions can be handled with nsimplify: >>> S('.[3]') # repeating digits in brackets 1/3 >>> S('32/10') # general expressions 9/10 >>> nsimplify(.3) # numbers that have a simple form 3/10 But if the input does not reduce to a literal Rational, an error will be raised: >>> Rational(pi) Traceback (most recent call last): ... TypeError: invalid input: pi Low-level --------- Access numerator and denominator as .p and .q: >>> r = Rational(3, 4) >>> r 3/4 >>> r.p 3 >>> r.q 4 Note that p and q return integers (not SymPy Integers) so some care is needed when using them in expressions: >>> r.p/r.q 0.75 See Also ======== sympify, sympy.simplify.simplify.nsimplify """ is_real = True is_integer = False is_rational = True is_number = True __slots__ = ['p', 'q'] is_Rational = True @cacheit def __new__(cls, p, q=None, gcd=None): if q is None: if isinstance(p, Rational): return p if isinstance(p, SYMPY_INTS): pass else: if isinstance(p, (float, Float)): return Rational(_as_integer_ratio(p)) if not isinstance(p, string_types): try: p = sympify(p) except (SympifyError, SyntaxError): pass # error will raise below else: if p.count('/') > 1: raise TypeError('invalid input: %s' % p) p = p.replace(' ', '') pq = p.rsplit('/', 1) if len(pq) == 2: p, q = pq fp = fractions.Fraction(p) fq = fractions.Fraction(q) p = fp/fq try: p = fractions.Fraction(p) except ValueError: pass # error will raise below else: return Rational(p.numerator, p.denominator, 1) if not isinstance(p, Rational): raise TypeError('invalid input: %s' % p) q = 1 gcd = 1 else: p = Rational(p) q = Rational(q) if isinstance(q, Rational): p = q.q q = q.p if isinstance(p, Rational): q = p.q p = p.p # p and q are now integers if q == 0: if p == 0: if _errdict["divide"]: raise ValueError("Indeterminate 0/0") else: return S.NaN return S.ComplexInfinity if q < 0: q = -q p = -p if not gcd: gcd = igcd(abs(p), q) if gcd > 1: p //= gcd q //= gcd if q == 1: return Integer(p) if p == 1 and q == 2: return S.Half obj = Expr.__new__(cls) obj.p = p obj.q = q return obj def limit_denominator(self, max_denominator=1000000): """Closest Rational to self with denominator at most max_denominator. >>> from sympy import Rational >>> Rational('3.141592653589793').limit_denominator(10) 22/7 >>> Rational('3.141592653589793').limit_denominator(100) 311/99 """ f = fractions.Fraction(self.p, self.q) return Rational(f.limit_denominator(fractions.Fraction(int(max_denominator)))) def __getnewargs__(self): return (self.p, self.q) def _hashable_content(self): return (self.p, self.q) def _eval_is_positive(self): return self.p > 0 def _eval_is_zero(self): return self.p == 0 def __neg__(self): return Rational(-self.p, self.q) @_sympifyit('other', NotImplemented) def __add__(self, other): if global_evaluate[0]: if isinstance(other, Integer): return Rational(self.p + self.qother.p, self.q, 1) elif isinstance(other, Rational): #TODO: this can probably be optimized more return Rational(self.pother.q + self.qother.p, self.qother.q) elif isinstance(other, Float): return other + self else: return Number.__add__(self, other) return Number.__add__(self, other) __radd__ = __add__ @_sympifyit('other', NotImplemented) def __sub__(self, other): if global_evaluate[0]: if isinstance(other, Integer): return Rational(self.p - self.qother.p, self.q, 1) elif isinstance(other, Rational): return Rational(self.pother.q - self.qother.p, self.qother.q) elif isinstance(other, Float): return -other + self else: return Number.__sub__(self, other) return Number.__sub__(self, other) @_sympifyit('other', NotImplemented) def __rsub__(self, other): if global_evaluate[0]: if isinstance(other, Integer): return Rational(self.qother.p - self.p, self.q, 1) elif isinstance(other, Rational): return Rational(self.qother.p - self.pother.q, self.qother.q) elif isinstance(other, Float): return -self + other else: return Number.__rsub__(self, other) return Number.__rsub__(self, other) @_sympifyit('other', NotImplemented) def __mul__(self, other): if global_evaluate[0]: if isinstance(other, Integer): return Rational(self.pother.p, self.q, igcd(other.p, self.q)) elif isinstance(other, Rational): return Rational(self.pother.p, self.qother.q, igcd(self.p, other.q)igcd(self.q, other.p)) elif isinstance(other, Float): return otherself else: return Number.__mul__(self, other) return Number.__mul__(self, other) __rmul__ = __mul__ @_sympifyit('other', NotImplemented) def __div__(self, other): if global_evaluate[0]: if isinstance(other, Integer): if self.p and other.p == S.Zero: return S.ComplexInfinity else: return Rational(self.p, self.qother.p, igcd(self.p, other.p)) elif isinstance(other, Rational): return Rational(self.pother.q, self.qother.p, igcd(self.p, other.p)igcd(self.q, other.q)) elif isinstance(other, Float): return self(1/other) else: return Number.__div__(self, other) return Number.__div__(self, other) @_sympifyit('other', NotImplemented) def __rdiv__(self, other): if global_evaluate[0]: if isinstance(other, Integer): return Rational(other.pself.q, self.p, igcd(self.p, other.p)) elif isinstance(other, Rational): return Rational(other.pself.q, other.qself.p, igcd(self.p, other.p)igcd(self.q, other.q)) elif isinstance(other, Float): return other(1/self) else: return Number.__rdiv__(self, other) return Number.__rdiv__(self, other) __truediv__ = __div__ @_sympifyit('other', NotImplemented) def __mod__(self, other): if global_evaluate[0]: if isinstance(other, Rational): n = (self.pother.q) // (other.pself.q) return Rational(self.pother.q - nother.pself.q, self.qother.q) if isinstance(other, Float): # calculate mod with Rationals, then* round the answer return Float(self.__mod__(Rational(other)), precision=other._prec) return Number.__mod__(self, other) return Number.__mod__(self, other) @_sympifyit('other', NotImplemented) def __rmod__(self, other): if isinstance(other, Rational): return Rational.__mod__(other, self) return Number.__rmod__(self, other) def _eval_power(self, expt): if isinstance(expt, Number): if isinstance(expt, Float): return self._eval_evalf(expt._prec)expt if expt.is_negative: # (3/4)-2 -> (4/3)2 ne = -expt if (ne is S.One): return Rational(self.q, self.p) if self.is_negative: return S.NegativeOneexptRational(self.q, -self.p)ne else: return Rational(self.q, self.p)ne if expt is S.Infinity: # -oo already caught by test for negative if self.p > self.q: # (3/2)oo -> oo return S.Infinity if self.p < -self.q: # (-3/2)oo -> oo + Ioo return S.Infinity + S.InfinityS.ImaginaryUnit return S.Zero if isinstance(expt, Integer): # (4/3)2 -> 42 / 32 return Rational(self.pexpt.p, self.qexpt.p, 1) if isinstance(expt, Rational): if self.p != 1: # (4/3)(5/6) -> 4(5/6)3(-5/6) return Integer(self.p)exptInteger(self.q)(-expt) # as the above caught negative self.p, now self is positive return Integer(self.q)Rational( expt.p(expt.q - 1), expt.q) / \ Integer(self.q)Integer(expt.p) if self.is_negative and expt.is_even: return (-self)expt return def _as_mpf_val(self, prec): return mlib.from_rational(self.p, self.q, prec, rnd) def _mpmath_(self, prec, rnd): return mpmath.make_mpf(mlib.from_rational(self.p, self.q, prec, rnd)) def __abs__(self): return Rational(abs(self.p), self.q) def __int__(self): p, q = self.p, self.q if p < 0: return -int(-p//q) return int(p//q) __long__ = __int__ def floor(self): return Integer(self.p // self.q) def ceiling(self): return -Integer(-self.p // self.q) def __eq__(self, other): try: other = _sympify(other) except SympifyError: return NotImplemented if other.is_NumberSymbol: if other.is_irrational: return False return other.__eq__(self) if other.is_Number: if other.is_Rational: # a Rational is always in reduced form so will never be 2/4 # so we can just check equivalence of args return self.p == other.p and self.q == other.q if other.is_Float: return mlib.mpf_eq(self._as_mpf_val(other._prec), other._mpf_) return False def __ne__(self, other): return not self == other def __gt__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s > %s" % (self, other)) if other.is_NumberSymbol: return other.__lt__(self) expr = self if other.is_Number: if other.is_Rational: return _sympify(bool(self.pother.q > self.qother.p)) if other.is_Float: return _sympify(bool(mlib.mpf_gt( self._as_mpf_val(other._prec), other._mpf_))) elif other.is_number and other.is_real: expr, other = Integer(self.p), self.qother return Expr.__gt__(expr, other) def __ge__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s >= %s" % (self, other)) if other.is_NumberSymbol: return other.__le__(self) expr = self if other.is_Number: if other.is_Rational: return _sympify(bool(self.pother.q >= self.qother.p)) if other.is_Float: return _sympify(bool(mlib.mpf_ge( self._as_mpf_val(other._prec), other._mpf_))) elif other.is_number and other.is_real: expr, other = Integer(self.p), self.qother return Expr.__ge__(expr, other) def __lt__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s < %s" % (self, other)) if other.is_NumberSymbol: return other.__gt__(self) expr = self if other.is_Number: if other.is_Rational: return _sympify(bool(self.pother.q < self.qother.p)) if other.is_Float: return _sympify(bool(mlib.mpf_lt( self._as_mpf_val(other._prec), other._mpf_))) elif other.is_number and other.is_real: expr, other = Integer(self.p), self.qother return Expr.__lt__(expr, other) def __le__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s <= %s" % (self, other)) expr = self if other.is_NumberSymbol: return other.__ge__(self) elif other.is_Number: if other.is_Rational: return _sympify(bool(self.pother.q <= self.qother.p)) if other.is_Float: return _sympify(bool(mlib.mpf_le( self._as_mpf_val(other._prec), other._mpf_))) elif other.is_number and other.is_real: expr, other = Integer(self.p), self.qother return Expr.__le__(expr, other) def __hash__(self): return super(Rational, self).__hash__() def factors(self, limit=None, use_trial=True, use_rho=False, use_pm1=False, verbose=False, visual=False): """A wrapper to factorint which return factors of self that are smaller than limit (or cheap to compute). Special methods of factoring are disabled by default so that only trial division is used. """ from sympy.ntheory import factorrat return factorrat(self, limit=limit, use_trial=use_trial, use_rho=use_rho, use_pm1=use_pm1, verbose=verbose).copy() @_sympifyit('other', NotImplemented) def gcd(self, other): if isinstance(other, Rational): if other is S.Zero: return other return Rational( Integer(igcd(self.p, other.p)), Integer(ilcm(self.q, other.q))) return Number.gcd(self, other) @_sympifyit('other', NotImplemented) def lcm(self, other): if isinstance(other, Rational): return Rational( self.p // igcd(self.p, other.p) * other.p, igcd(self.q, other.q)) return Number.lcm(self, other) def as_numer_denom(self): return Integer(self.p), Integer(self.q) def _sage_(self): import sage.all as sage return sage.Integer(self.p)/sage.Integer(self.q) def as_content_primitive(self, radical=False, clear=True): """Return the tuple (R, self/R) where R is the positive Rational extracted from self. Examples ======== >>> from sympy import S >>> (S(-3)/2).as_content_primitive() (3/2, -1) See docstring of Expr.as_content_primitive for more examples. """ if self: if self.is_positive: return self, S.One return -self, S.NegativeOne return S.One, self def as_coeff_Mul(self, rational=False): """Efficiently extract the coefficient of a product. """ return self, S.One def as_coeff_Add(self, rational=False): """Efficiently extract the coefficient of a summation. """ return self, S.Zero # int -> Integer _intcache = {} # TODO move this tracing facility to sympy/core/trace.py ? def _intcache_printinfo(): ints = sorted(_intcache.keys()) nhit = _intcache_hits nmiss = _intcache_misses if nhit == 0 and nmiss == 0: print() print('Integer cache statistic was not collected') return miss_ratio = float(nmiss) / (nhit + nmiss) print() print('Integer cache statistic') print('-----------------------') print() print('#items: %i' % len(ints)) print() print(' #hit #miss #total') print() print('%5i %5i (%7.5f %%) %5i' % ( nhit, nmiss, miss_ratio100, nhit + nmiss) ) print() print(ints) _intcache_hits = 0 _intcache_misses = 0 def int_trace(f): import os if os.getenv('SYMPY_TRACE_INT', 'no').lower() != 'yes': return f def Integer_tracer(cls, i): global _intcache_hits, _intcache_misses try: _intcache_hits += 1 return _intcache[i] except KeyError: _intcache_hits -= 1 _intcache_misses += 1 return f(cls, i) # also we want to hook our _intcache_printinfo into sys.atexit import atexit atexit.register(_intcache_printinfo) return Integer_tracer class Integer(Rational): """Represents integer numbers of any size. Examples ======== >>> from sympy import Integer >>> Integer(3) 3 If a float or a rational is passed to Integer, the fractional part will be discarded; the effect is of rounding toward zero. >>> Integer(3.8) 3 >>> Integer(-3.8) -3 A string is acceptable input if it can be parsed as an integer: >>> Integer("9" 20) 99999999999999999999 It is rarely needed to explicitly instantiate an Integer, because Python integers are automatically converted to Integer when they are used in SymPy expressions. """ q = 1 is_integer = True is_number = True is_Integer = True __slots__ = ['p'] def _as_mpf_val(self, prec): return mlib.from_int(self.p, prec, rnd) def _mpmath_(self, prec, rnd): return mpmath.make_mpf(self._as_mpf_val(prec)) # TODO caching with decorator, but not to degrade performance @int_trace def __new__(cls, i): if isinstance(i, string_types): i = i.replace(' ', '') # whereas we cannot, in general, make a Rational from an # arbitrary expression, we can make an Integer unambiguously # (except when a non-integer expression happens to round to # an integer). So we proceed by taking int() of the input and # let the int routines determine whether the expression can # be made into an int or whether an error should be raised. try: ival = int(i) except TypeError: raise TypeError( "Argument of Integer should be of numeric type, got %s." % i) try: return _intcache[ival] except KeyError: # We only work with well-behaved integer types. This converts, for # example, numpy.int32 instances. obj = Expr.__new__(cls) obj.p = ival _intcache[ival] = obj return obj def __getnewargs__(self): return (self.p,) # Arithmetic operations are here for efficiency def __int__(self): return self.p __long__ = __int__ def floor(self): return Integer(self.p) def ceiling(self): return Integer(self.p) def __neg__(self): return Integer(-self.p) def __abs__(self): if self.p >= 0: return self else: return Integer(-self.p) def __divmod__(self, other): from .containers import Tuple if isinstance(other, Integer) and global_evaluate[0]: return Tuple((divmod(self.p, other.p))) else: return Number.__divmod__(self, other) def __rdivmod__(self, other): from .containers import Tuple if isinstance(other, integer_types) and global_evaluate[0]: return Tuple((divmod(other, self.p))) else: try: other = Number(other) except TypeError: msg = "unsupported operand type(s) for divmod(): '%s' and '%s'" oname = type(other).__name__ sname = type(self).__name__ raise TypeError(msg % (oname, sname)) return Number.__divmod__(other, self) # TODO make it decorator + bytecodehacks? def __add__(self, other): if global_evaluate[0]: if isinstance(other, integer_types): return Integer(self.p + other) elif isinstance(other, Integer): return Integer(self.p + other.p) elif isinstance(other, Rational): return Rational(self.pother.q + other.p, other.q, 1) return Rational.__add__(self, other) else: return Add(self, other) def __radd__(self, other): if global_evaluate[0]: if isinstance(other, integer_types): return Integer(other + self.p) elif isinstance(other, Rational): return Rational(other.p + self.pother.q, other.q, 1) return Rational.__radd__(self, other) return Rational.__radd__(self, other) def __sub__(self, other): if global_evaluate[0]: if isinstance(other, integer_types): return Integer(self.p - other) elif isinstance(other, Integer): return Integer(self.p - other.p) elif isinstance(other, Rational): return Rational(self.pother.q - other.p, other.q, 1) return Rational.__sub__(self, other) return Rational.__sub__(self, other) def __rsub__(self, other): if global_evaluate[0]: if isinstance(other, integer_types): return Integer(other - self.p) elif isinstance(other, Rational): return Rational(other.p - self.pother.q, other.q, 1) return Rational.__rsub__(self, other) return Rational.__rsub__(self, other) def __mul__(self, other): if global_evaluate[0]: if isinstance(other, integer_types): return Integer(self.pother) elif isinstance(other, Integer): return Integer(self.pother.p) elif isinstance(other, Rational): return Rational(self.pother.p, other.q, igcd(self.p, other.q)) return Rational.__mul__(self, other) return Rational.__mul__(self, other) def __rmul__(self, other): if global_evaluate[0]: if isinstance(other, integer_types): return Integer(otherself.p) elif isinstance(other, Rational): return Rational(other.pself.p, other.q, igcd(self.p, other.q)) return Rational.__rmul__(self, other) return Rational.__rmul__(self, other) def __mod__(self, other): if global_evaluate[0]: if isinstance(other, integer_types): return Integer(self.p % other) elif isinstance(other, Integer): return Integer(self.p % other.p) return Rational.__mod__(self, other) return Rational.__mod__(self, other) def __rmod__(self, other): if global_evaluate[0]: if isinstance(other, integer_types): return Integer(other % self.p) elif isinstance(other, Integer): return Integer(other.p % self.p) return Rational.__rmod__(self, other) return Rational.__rmod__(self, other) def __eq__(self, other): if isinstance(other, integer_types): return (self.p == other) elif isinstance(other, Integer): return (self.p == other.p) return Rational.__eq__(self, other) def __ne__(self, other): return not self == other def __gt__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s > %s" % (self, other)) if other.is_Integer: return _sympify(self.p > other.p) return Rational.__gt__(self, other) def __lt__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s < %s" % (self, other)) if other.is_Integer: return _sympify(self.p < other.p) return Rational.__lt__(self, other) def __ge__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s >= %s" % (self, other)) if other.is_Integer: return _sympify(self.p >= other.p) return Rational.__ge__(self, other) def __le__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s <= %s" % (self, other)) if other.is_Integer: return _sympify(self.p <= other.p) return Rational.__le__(self, other) def __hash__(self): return hash(self.p) def __index__(self): return self.p ######################################## def _eval_is_odd(self): return bool(self.p % 2) def _eval_power(self, expt): """ Tries to do some simplifications on selfexpt Returns None if no further simplifications can be done When exponent is a fraction (so we have for example a square root), we try to find a simpler representation by factoring the argument up to factors of 215, e.g. - sqrt(4) becomes 2 - sqrt(-4) becomes 2I - (2*(3+7)3(6+7))Rational(1,7) becomes 618(3/7) Further simplification would require a special call to factorint on the argument which is not done here for sake of speed. """ from sympy import perfect_power if expt is S.Infinity: if self.p > S.One: return S.Infinity # cases -1, 0, 1 are done in their respective classes return S.Infinity + S.ImaginaryUnitS.Infinity if expt is S.NegativeInfinity: return Rational(1, self)S.Infinity if not isinstance(expt, Number): # simplify when expt is even # (-2)k --> 2k if self.is_negative and expt.is_even: return (-self)expt if isinstance(expt, Float): # Rational knows how to exponentiate by a Float return super(Integer, self)._eval_power(expt) if not isinstance(expt, Rational): return if expt is S.Half and self.is_negative: # we extract I for this special case since everyone is doing so return S.ImaginaryUnitPow(-self, expt) if expt.is_negative: # invert base and change sign on exponent ne = -expt if self.is_negative: return S.NegativeOneexptRational(1, -self)ne else: return Rational(1, self.p)ne # see if base is a perfect root, sqrt(4) --> 2 x, xexact = integer_nthroot(abs(self.p), expt.q) if xexact: # if it's a perfect root we've finished result = Integer(x*abs(expt.p)) if self.is_negative: result = S.NegativeOneexpt return result # The following is an algorithm where we collect perfect roots # from the factors of base. # if it's not an nth root, it still might be a perfect power b_pos = int(abs(self.p)) p = perfect_power(b_pos) if p is not False: dict = {p[0]: p[1]} else: dict = Integer(b_pos).factors(limit=215) # now process the dict of factors out_int = 1 # integer part out_rad = 1 # extracted radicals sqr_int = 1 sqr_gcd = 0 sqr_dict = {} for prime, exponent in dict.items(): exponent = expt.p # remove multiples of expt.q: (212)(1/10) -> 2(22)(1/10) div_e, div_m = divmod(exponent, expt.q) if div_e > 0: out_int = primediv_e if div_m > 0: # see if the reduced exponent shares a gcd with e.q # (22)(1/10) -> 2(1/5) g = igcd(div_m, expt.q) if g != 1: out_rad = Pow(prime, Rational(div_m//g, expt.q//g)) else: sqr_dict[prime] = div_m # identify gcd of remaining powers for p, ex in sqr_dict.items(): if sqr_gcd == 0: sqr_gcd = ex else: sqr_gcd = igcd(sqr_gcd, ex) if sqr_gcd == 1: break for k, v in sqr_dict.items(): sqr_int = k(v//sqr_gcd) if sqr_int == b_pos and out_int == 1 and out_rad == 1: result = None else: result = out_intout_radPow(sqr_int, Rational(sqr_gcd, expt.q)) if self.is_negative: result = Pow(S.NegativeOne, expt) return result def _eval_is_prime(self): from sympy.ntheory import isprime return isprime(self) def _eval_is_composite(self): if self > 1: return fuzzy_not(self.is_prime) else: return False def as_numer_denom(self): return self, S.One def __floordiv__(self, other): return Integer(self.p // Integer(other).p) def __rfloordiv__(self, other): return Integer(Integer(other).p // self.p) # Add sympify converters for i_type in integer_types: converter[i_type] = Integer class AlgebraicNumber(Expr): """Class for representing algebraic numbers in SymPy. """ __slots__ = ['rep', 'root', 'alias', 'minpoly'] is_AlgebraicNumber = True is_algebraic = True is_number = True def __new__(cls, expr, coeffs=None, alias=None, *args): """Construct a new algebraic number. """ from sympy import Poly from sympy.polys.polyclasses import ANP, DMP from sympy.polys.numberfields import minimal_polynomial from sympy.core.symbol import Symbol expr = sympify(expr) if isinstance(expr, (tuple, Tuple)): minpoly, root = expr if not minpoly.is_Poly: minpoly = Poly(minpoly) elif expr.is_AlgebraicNumber: minpoly, root = expr.minpoly, expr.root else: minpoly, root = minimal_polynomial( expr, args.get('gen'), polys=True), expr dom = minpoly.get_domain() if coeffs is not None: if not isinstance(coeffs, ANP): rep = DMP.from_sympy_list(sympify(coeffs), 0, dom) scoeffs = Tuple(coeffs) else: rep = DMP.from_list(coeffs.to_list(), 0, dom) scoeffs = Tuple(coeffs.to_list()) if rep.degree() >= minpoly.degree(): rep = rep.rem(minpoly.rep) else: rep = DMP.from_list([1, 0], 0, dom) scoeffs = Tuple(1, 0) sargs = (root, scoeffs) if alias is not None: if not isinstance(alias, Symbol): alias = Symbol(alias) sargs = sargs + (alias,) obj = Expr.__new__(cls, sargs) obj.rep = rep obj.root = root obj.alias = alias obj.minpoly = minpoly return obj def __hash__(self): return super(AlgebraicNumber, self).__hash__() def _eval_evalf(self, prec): return self.as_expr()._evalf(prec) @property def is_aliased(self): """Returns ``True`` if ``alias`` was set. """ return self.alias is not None def as_poly(self, x=None): """Create a Poly instance from ``self``. """ from sympy import Dummy, Poly, PurePoly if x is not None: return Poly.new(self.rep, x) else: if self.alias is not None: return Poly.new(self.rep, self.alias) else: return PurePoly.new(self.rep, Dummy('x')) def as_expr(self, x=None): """Create a Basic expression from ``self``. """ return self.as_poly(x or self.root).as_expr().expand() def coeffs(self): """Returns all SymPy coefficients of an algebraic number. """ return [ self.rep.dom.to_sympy(c) for c in self.rep.all_coeffs() ] def native_coeffs(self): """Returns all native coefficients of an algebraic number. """ return self.rep.all_coeffs() def to_algebraic_integer(self): """Convert ``self`` to an algebraic integer. """ from sympy import Poly f = self.minpoly if f.LC() == 1: return self coeff = f.LC()*(f.degree() - 1) poly = f.compose(Poly(f.gen/f.LC())) minpoly = polycoeff root = f.LC()self.root return AlgebraicNumber((minpoly, root), self.coeffs()) def _eval_simplify(self, ratio, measure, rational, inverse): from sympy.polys import CRootOf, minpoly for r in [r for r in self.minpoly.all_roots() if r.func != CRootOf]: if minpoly(self.root - r).is_Symbol: # use the matching root if it's simpler if measure(r) < ratiomeasure(self.root): return AlgebraicNumber(r) return self class RationalConstant(Rational): """ Abstract base class for rationals with specific behaviors Derived classes must define class attributes p and q and should probably all be singletons. """ __slots__ = [] def __new__(cls): return AtomicExpr.__new__(cls) class IntegerConstant(Integer): __slots__ = [] def __new__(cls): return AtomicExpr.__new__(cls) class Zero(with_metaclass(Singleton, IntegerConstant)): """The number zero. Zero is a singleton, and can be accessed by ``S.Zero`` Examples ======== >>> from sympy import S, Integer, zoo >>> Integer(0) is S.Zero True >>> 1/S.Zero zoo References ========== .. [1] https://en.wikipedia.org/wiki/Zero """ p = 0 q = 1 is_positive = False is_negative = False is_zero = True is_number = True __slots__ = [] @staticmethod def __abs__(): return S.Zero @staticmethod def __neg__(): return S.Zero def _eval_power(self, expt): if expt.is_positive: return self if expt.is_negative: return S.ComplexInfinity if expt.is_real is False: return S.NaN # infinities are already handled with pos and neg # tests above; now throw away leading numbers on Mul # exponent coeff, terms = expt.as_coeff_Mul() if coeff.is_negative: return S.ComplexInfinityterms if coeff is not S.One: # there is a Number to discard return selfterms def _eval_order(self, symbols): # Order(0,x) -> 0 return self def __nonzero__(self): return False __bool__ = __nonzero__ def as_coeff_Mul(self, rational=False): # XXX this routine should be deleted """Efficiently extract the coefficient of a summation. """ return S.One, self class One(with_metaclass(Singleton, IntegerConstant)): """The number one. One is a singleton, and can be accessed by ``S.One``. Examples ======== >>> from sympy import S, Integer >>> Integer(1) is S.One True References ========== .. [1] https://en.wikipedia.org/wiki/1_%28number%29 """ is_number = True p = 1 q = 1 __slots__ = [] @staticmethod def __abs__(): return S.One @staticmethod def __neg__(): return S.NegativeOne def _eval_power(self, expt): return self def _eval_order(self, symbols): return @staticmethod def factors(limit=None, use_trial=True, use_rho=False, use_pm1=False, verbose=False, visual=False): if visual: return S.One else: return {} class NegativeOne(with_metaclass(Singleton, IntegerConstant)): """The number negative one. NegativeOne is a singleton, and can be accessed by ``S.NegativeOne``. Examples ======== >>> from sympy import S, Integer >>> Integer(-1) is S.NegativeOne True See Also ======== One References ========== .. [1] https://en.wikipedia.org/wiki/%E2%88%921_%28number%29 """ is_number = True p = -1 q = 1 __slots__ = [] @staticmethod def __abs__(): return S.One @staticmethod def __neg__(): return S.One def _eval_power(self, expt): if expt.is_odd: return S.NegativeOne if expt.is_even: return S.One if isinstance(expt, Number): if isinstance(expt, Float): return Float(-1.0)expt if expt is S.NaN: return S.NaN if expt is S.Infinity or expt is S.NegativeInfinity: return S.NaN if expt is S.Half: return S.ImaginaryUnit if isinstance(expt, Rational): if expt.q == 2: return S.ImaginaryUnitInteger(expt.p) i, r = divmod(expt.p, expt.q) if i: return self*iselfRational(r, expt.q) return class Half(with_metaclass(Singleton, RationalConstant)): """The rational number 1/2. Half is a singleton, and can be accessed by ``S.Half``. Examples ======== >>> from sympy import S, Rational >>> Rational(1, 2) is S.Half True References ========== .. [1] https://en.wikipedia.org/wiki/One_half """ is_number = True p = 1 q = 2 __slots__ = [] @staticmethod def __abs__(): return S.Half class Infinity(with_metaclass(Singleton, Number)): r"""Positive infinite quantity. In real analysis the symbol `\infty` denotes an unbounded limit: `x\to\infty` means that `x` grows without bound. Infinity is often used not only to define a limit but as a value in the affinely extended real number system. Points labeled `+\infty` and `-\infty` can be added to the topological space of the real numbers, producing the two-point compactification of the real numbers. Adding algebraic properties to this gives us the extended real numbers. Infinity is a singleton, and can be accessed by ``S.Infinity``, or can be imported as ``oo``. Examples ======== >>> from sympy import oo, exp, limit, Symbol >>> 1 + oo oo >>> 42/oo 0 >>> x = Symbol('x') >>> limit(exp(x), x, oo) oo See Also ======== NegativeInfinity, NaN References ========== .. [1] https://en.wikipedia.org/wiki/Infinity """ is_commutative = True is_positive = True is_infinite = True is_number = True is_prime = False __slots__ = [] def __new__(cls): return AtomicExpr.__new__(cls) def _latex(self, printer): return r"\infty" def _eval_subs(self, old, new): if self == old: return new @_sympifyit('other', NotImplemented) def __add__(self, other): if isinstance(other, Number): if other is S.NegativeInfinity or other is S.NaN: return S.NaN elif other.is_Float: if other == Float('-inf'): return S.NaN else: return Float('inf') else: return S.Infinity return NotImplemented __radd__ = __add__ @_sympifyit('other', NotImplemented) def __sub__(self, other): if isinstance(other, Number): if other is S.Infinity or other is S.NaN: return S.NaN elif other.is_Float: if other == Float('inf'): return S.NaN else: return Float('inf') else: return S.Infinity return NotImplemented @_sympifyit('other', NotImplemented) def __mul__(self, other): if isinstance(other, Number): if other is S.Zero or other is S.NaN: return S.NaN elif other.is_Float: if other == 0: return S.NaN if other > 0: return Float('inf') else: return Float('-inf') else: if other > 0: return S.Infinity else: return S.NegativeInfinity return NotImplemented __rmul__ = __mul__ @_sympifyit('other', NotImplemented) def __div__(self, other): if isinstance(other, Number): if other is S.Infinity or \ other is S.NegativeInfinity or \ other is S.NaN: return S.NaN elif other.is_Float: if other == Float('-inf') or \ other == Float('inf'): return S.NaN elif other.is_nonnegative: return Float('inf') else: return Float('-inf') else: if other >= 0: return S.Infinity else: return S.NegativeInfinity return NotImplemented __truediv__ = __div__ def __abs__(self): return S.Infinity def __neg__(self): return S.NegativeInfinity def _eval_power(self, expt): """ ``expt`` is symbolic object but not equal to 0 or 1. ================ ======= ============================== Expression Result Notes ================ ======= ============================== ``oo nan`` ``nan`` ``oo -p`` ``0`` ``p`` is number, ``oo`` ================ ======= ============================== See Also ======== Pow NaN NegativeInfinity """ from sympy.functions import re if expt.is_positive: return S.Infinity if expt.is_negative: return S.Zero if expt is S.NaN: return S.NaN if expt is S.ComplexInfinity: return S.NaN if expt.is_real is False and expt.is_number: expt_real = re(expt) if expt_real.is_positive: return S.ComplexInfinity if expt_real.is_negative: return S.Zero if expt_real.is_zero: return S.NaN return selfexpt.evalf() def _as_mpf_val(self, prec): return mlib.finf def _sage_(self): import sage.all as sage return sage.oo def __hash__(self): return super(Infinity, self).__hash__() def __eq__(self, other): return other is S.Infinity def __ne__(self, other): return other is not S.Infinity def __lt__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s < %s" % (self, other)) if other.is_real: return S.false return Expr.__lt__(self, other) def __le__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s <= %s" % (self, other)) if other.is_real: if other.is_finite or other is S.NegativeInfinity: return S.false elif other.is_nonpositive: return S.false elif other.is_infinite and other.is_positive: return S.true return Expr.__le__(self, other) def __gt__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s > %s" % (self, other)) if other.is_real: if other.is_finite or other is S.NegativeInfinity: return S.true elif other.is_nonpositive: return S.true elif other.is_infinite and other.is_positive: return S.false return Expr.__gt__(self, other) def __ge__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s >= %s" % (self, other)) if other.is_real: return S.true return Expr.__ge__(self, other) def __mod__(self, other): return S.NaN __rmod__ = __mod__ def floor(self): return self def ceiling(self): return self oo = S.Infinity class NegativeInfinity(with_metaclass(Singleton, Number)): """Negative infinite quantity. NegativeInfinity is a singleton, and can be accessed by ``S.NegativeInfinity``. See Also ======== Infinity """ is_commutative = True is_negative = True is_infinite = True is_number = True __slots__ = [] def __new__(cls): return AtomicExpr.__new__(cls) def _latex(self, printer): return r"-\infty" def _eval_subs(self, old, new): if self == old: return new @_sympifyit('other', NotImplemented) def __add__(self, other): if isinstance(other, Number): if other is S.Infinity or other is S.NaN: return S.NaN elif other.is_Float: if other == Float('inf'): return Float('nan') else: return Float('-inf') else: return S.NegativeInfinity return NotImplemented __radd__ = __add__ @_sympifyit('other', NotImplemented) def __sub__(self, other): if isinstance(other, Number): if other is S.NegativeInfinity or other is S.NaN: return S.NaN elif other.is_Float: if other == Float('-inf'): return Float('nan') else: return Float('-inf') else: return S.NegativeInfinity return NotImplemented @_sympifyit('other', NotImplemented) def __mul__(self, other): if isinstance(other, Number): if other is S.Zero or other is S.NaN: return S.NaN elif other.is_Float: if other is S.NaN or other.is_zero: return S.NaN elif other.is_positive: return Float('-inf') else: return Float('inf') else: if other.is_positive: return S.NegativeInfinity else: return S.Infinity return NotImplemented __rmul__ = __mul__ @_sympifyit('other', NotImplemented) def __div__(self, other): if isinstance(other, Number): if other is S.Infinity or \ other is S.NegativeInfinity or \ other is S.NaN: return S.NaN elif other.is_Float: if other == Float('-inf') or \ other == Float('inf') or \ other is S.NaN: return S.NaN elif other.is_nonnegative: return Float('-inf') else: return Float('inf') else: if other >= 0: return S.NegativeInfinity else: return S.Infinity return NotImplemented __truediv__ = __div__ def __abs__(self): return S.Infinity def __neg__(self): return S.Infinity def _eval_power(self, expt): """ ``expt`` is symbolic object but not equal to 0 or 1. ================ ======= ============================== Expression Result Notes ================ ======= ============================== ``(-oo) nan`` ``nan`` ``(-oo) oo`` ``nan`` ``(-oo) -oo`` ``nan`` ``(-oo) e`` ``oo`` ``e`` is positive even integer ``(-oo) o`` ``-oo`` ``o`` is positive odd integer ================ ======= ============================== See Also ======== Infinity Pow NaN """ if expt.is_number: if expt is S.NaN or \ expt is S.Infinity or \ expt is S.NegativeInfinity: return S.NaN if isinstance(expt, Integer) and expt.is_positive: if expt.is_odd: return S.NegativeInfinity else: return S.Infinity return S.NegativeOneexptS.Infinityexpt def _as_mpf_val(self, prec): return mlib.fninf def _sage_(self): import sage.all as sage return -(sage.oo) def __hash__(self): return super(NegativeInfinity, self).__hash__() def __eq__(self, other): return other is S.NegativeInfinity def __ne__(self, other): return other is not S.NegativeInfinity def __lt__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s < %s" % (self, other)) if other.is_real: if other.is_finite or other is S.Infinity: return S.true elif other.is_nonnegative: return S.true elif other.is_infinite and other.is_negative: return S.false return Expr.__lt__(self, other) def __le__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s <= %s" % (self, other)) if other.is_real: return S.true return Expr.__le__(self, other) def __gt__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s > %s" % (self, other)) if other.is_real: return S.false return Expr.__gt__(self, other) def __ge__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s >= %s" % (self, other)) if other.is_real: if other.is_finite or other is S.Infinity: return S.false elif other.is_nonnegative: return S.false elif other.is_infinite and other.is_negative: return S.true return Expr.__ge__(self, other) def __mod__(self, other): return S.NaN __rmod__ = __mod__ def floor(self): return self def ceiling(self): return self class NaN(with_metaclass(Singleton, Number)): """ Not a Number. This serves as a place holder for numeric values that are indeterminate. Most operations on NaN, produce another NaN. Most indeterminate forms, such as ``0/0`` or ``oo - oo` produce NaN. Two exceptions are ``00`` and ``oo0``, which all produce ``1`` (this is consistent with Python's float). NaN is loosely related to floating point nan, which is defined in the IEEE 754 floating point standard, and corresponds to the Python ``float('nan')``. Differences are noted below. NaN is mathematically not equal to anything else, even NaN itself. This explains the initially counter-intuitive results with ``Eq`` and ``==`` in the examples below. NaN is not comparable so inequalities raise a TypeError. This is in constrast with floating point nan where all inequalities are false. NaN is a singleton, and can be accessed by ``S.NaN``, or can be imported as ``nan``. Examples ======== >>> from sympy import nan, S, oo, Eq >>> nan is S.NaN True >>> oo - oo nan >>> nan + 1 nan >>> Eq(nan, nan) # mathematical equality False >>> nan == nan # structural equality True References ========== .. [1] https://en.wikipedia.org/wiki/NaN """ is_commutative = True is_real = None is_rational = None is_algebraic = None is_transcendental = None is_integer = None is_comparable = False is_finite = None is_zero = None is_prime = None is_positive = None is_negative = None is_number = True __slots__ = [] def __new__(cls): return AtomicExpr.__new__(cls) def _latex(self, printer): return r"\mathrm{NaN}" @_sympifyit('other', NotImplemented) def __add__(self, other): return self @_sympifyit('other', NotImplemented) def __sub__(self, other): return self @_sympifyit('other', NotImplemented) def __mul__(self, other): return self @_sympifyit('other', NotImplemented) def __div__(self, other): return self __truediv__ = __div__ def floor(self): return self def ceiling(self): return self def _as_mpf_val(self, prec): return _mpf_nan def _sage_(self): import sage.all as sage return sage.NaN def __hash__(self): return super(NaN, self).__hash__() def __eq__(self, other): # NaN is structurally equal to another NaN return other is S.NaN def __ne__(self, other): return other is not S.NaN def _eval_Eq(self, other): # NaN is not mathematically equal to anything, even NaN return S.false # Expr will _sympify and raise TypeError __gt__ = Expr.__gt__ __ge__ = Expr.__ge__ __lt__ = Expr.__lt__ __le__ = Expr.__le__ nan = S.NaN class ComplexInfinity(with_metaclass(Singleton, AtomicExpr)): r"""Complex infinity. In complex analysis the symbol `\tilde\infty`, called "complex infinity", represents a quantity with infinite magnitude, but undetermined complex phase. ComplexInfinity is a singleton, and can be accessed by ``S.ComplexInfinity``, or can be imported as ``zoo``. Examples ======== >>> from sympy import zoo, oo >>> zoo + 42 zoo >>> 42/zoo 0 >>> zoo + zoo nan >>> zoozoo zoo See Also ======== Infinity """ is_commutative = True is_infinite = True is_number = True is_prime = False is_complex = True is_real = False __slots__ = [] def __new__(cls): return AtomicExpr.__new__(cls) def _latex(self, printer): return r"\tilde{\infty}" @staticmethod def __abs__(): return S.Infinity def floor(self): return self def ceiling(self): return self @staticmethod def __neg__(): return S.ComplexInfinity def _eval_power(self, expt): if expt is S.ComplexInfinity: return S.NaN if isinstance(expt, Number): if expt is S.Zero: return S.NaN else: if expt.is_positive: return S.ComplexInfinity else: return S.Zero def _sage_(self): import sage.all as sage return sage.UnsignedInfinityRing.gen() zoo = S.ComplexInfinity class NumberSymbol(AtomicExpr): is_commutative = True is_finite = True is_number = True __slots__ = [] is_NumberSymbol = True def __new__(cls): return AtomicExpr.__new__(cls) def approximation(self, number_cls): """ Return an interval with number_cls endpoints that contains the value of NumberSymbol. If not implemented, then return None. """ def _eval_evalf(self, prec): return Float._new(self._as_mpf_val(prec), prec) def __eq__(self, other): try: other = _sympify(other) except SympifyError: return NotImplemented if self is other: return True if other.is_Number and self.is_irrational: return False return False # NumberSymbol != non-(Number\|self) def __ne__(self, other): return not self == other def __le__(self, other): if self is other: return S.true return Expr.__le__(self, other) def __ge__(self, other): if self is other: return S.true return Expr.__ge__(self, other) def __int__(self): # subclass with appropriate return value raise NotImplementedError def __long__(self): return self.__int__() def __hash__(self): return super(NumberSymbol, self).__hash__() class Exp1(with_metaclass(Singleton, NumberSymbol)): r"""The `e` constant. The transcendental number `e = 2.718281828\ldots` is the base of the natural logarithm and of the exponential function, `e = \exp(1)`. Sometimes called Euler's number or Napier's constant. Exp1 is a singleton, and can be accessed by ``S.Exp1``, or can be imported as ``E``. Examples ======== >>> from sympy import exp, log, E >>> E is exp(1) True >>> log(E) 1 References ========== .. [1] https://en.wikipedia.org/wiki/E_%28mathematical_constant%29 """ is_real = True is_positive = True is_negative = False # XXX Forces is_negative/is_nonnegative is_irrational = True is_number = True is_algebraic = False is_transcendental = True __slots__ = [] def _latex(self, printer): return r"e" @staticmethod def __abs__(): return S.Exp1 def __int__(self): return 2 def _as_mpf_val(self, prec): return mpf_e(prec) def approximation_interval(self, number_cls): if issubclass(number_cls, Integer): return (Integer(2), Integer(3)) elif issubclass(number_cls, Rational): pass def _eval_power(self, expt): from sympy import exp return exp(expt) def _eval_rewrite_as_sin(self, *kwargs): from sympy import sin I = S.ImaginaryUnit return sin(I + S.Pi/2) - Isin(I) def _eval_rewrite_as_cos(self, *kwargs): from sympy import cos I = S.ImaginaryUnit return cos(I) + Icos(I + S.Pi/2) def _sage_(self): import sage.all as sage return sage.e E = S.Exp1 class Pi(with_metaclass(Singleton, NumberSymbol)): r"""The `\pi` constant. The transcendental number `\pi = 3.141592654\ldots` represents the ratio of a circle's circumference to its diameter, the area of the unit circle, the half-period of trigonometric functions, and many other things in mathematics. Pi is a singleton, and can be accessed by ``S.Pi``, or can be imported as ``pi``. Examples ======== >>> from sympy import S, pi, oo, sin, exp, integrate, Symbol >>> S.Pi pi >>> pi > 3 True >>> pi.is_irrational True >>> x = Symbol('x') >>> sin(x + 2pi) sin(x) >>> integrate(exp(-x2), (x, -oo, oo)) sqrt(pi) References ========== .. [1] https://en.wikipedia.org/wiki/Pi """ is_real = True is_positive = True is_negative = False is_irrational = True is_number = True is_algebraic = False is_transcendental = True __slots__ = [] def _latex(self, printer): return r"\pi" @staticmethod def __abs__(): return S.Pi def __int__(self): return 3 def _as_mpf_val(self, prec): return mpf_pi(prec) def approximation_interval(self, number_cls): if issubclass(number_cls, Integer): return (Integer(3), Integer(4)) elif issubclass(number_cls, Rational): return (Rational(223, 71), Rational(22, 7)) def _sage_(self): import sage.all as sage return sage.pi pi = S.Pi class GoldenRatio(with_metaclass(Singleton, NumberSymbol)): r"""The golden ratio, `\phi`. `\phi = \frac{1 + \sqrt{5}}{2}` is algebraic number. Two quantities are in the golden ratio if their ratio is the same as the ratio of their sum to the larger of the two quantities, i.e. their maximum. GoldenRatio is a singleton, and can be accessed by ``S.GoldenRatio``. Examples ======== >>> from sympy import S >>> S.GoldenRatio > 1 True >>> S.GoldenRatio.expand(func=True) 1/2 + sqrt(5)/2 >>> S.GoldenRatio.is_irrational True References ========== .. [1] https://en.wikipedia.org/wiki/Golden_ratio """ is_real = True is_positive = True is_negative = False is_irrational = True is_number = True is_algebraic = True is_transcendental = False __slots__ = [] def _latex(self, printer): return r"\phi" def __int__(self): return 1 def _as_mpf_val(self, prec): # XXX track down why this has to be increased rv = mlib.from_man_exp(phi_fixed(prec + 10), -prec - 10) return mpf_norm(rv, prec) def _eval_expand_func(self, hints): from sympy import sqrt return S.Half + S.Halfsqrt(5) def approximation_interval(self, number_cls): if issubclass(number_cls, Integer): return (S.One, Rational(2)) elif issubclass(number_cls, Rational): pass def _sage_(self): import sage.all as sage return sage.golden_ratio _eval_rewrite_as_sqrt = _eval_expand_func class TribonacciConstant(with_metaclass(Singleton, NumberSymbol)): r"""The tribonacci constant. The tribonacci numbers are like the Fibonacci numbers, but instead of starting with two predetermined terms, the sequence starts with three predetermined terms and each term afterwards is the sum of the preceding three terms. The tribonacci constant is the ratio toward which adjacent tribonacci numbers tend. It is a root of the polynomial `x^3 - x^2 - x - 1 = 0`, and also satisfies the equation `x + x^{-3} = 2`. TribonacciConstant is a singleton, and can be accessed by ``S.TribonacciConstant``. Examples ======== >>> from sympy import S >>> S.TribonacciConstant > 1 True >>> S.TribonacciConstant.expand(func=True) 1/3 + (-3sqrt(33) + 19)(1/3)/3 + (3sqrt(33) + 19)(1/3)/3 >>> S.TribonacciConstant.is_irrational True >>> S.TribonacciConstant.n(20) 1.8392867552141611326 References ========== .. [1] https://en.wikipedia.org/wiki/Generalizations_of_Fibonacci_numbers#Tribonacci_numbers """ is_real = True is_positive = True is_negative = False is_irrational = True is_number = True is_algebraic = True is_transcendental = False __slots__ = [] def _latex(self, printer): return r"\mathrm{TribonacciConstant}" def __int__(self): return 2 def _eval_evalf(self, prec): rv = self._eval_expand_func(function=True)._eval_evalf(prec + 4) return Float(rv, precision=prec) def _eval_expand_func(self, hints): from sympy import sqrt, cbrt return (1 + cbrt(19 - 3sqrt(33)) + cbrt(19 + 3sqrt(33))) / 3 def approximation_interval(self, number_cls): if issubclass(number_cls, Integer): return (S.One, Rational(2)) elif issubclass(number_cls, Rational): pass _eval_rewrite_as_sqrt = _eval_expand_func class EulerGamma(with_metaclass(Singleton, NumberSymbol)): r"""The Euler-Mascheroni constant. `\gamma = 0.5772157\ldots` (also called Euler's constant) is a mathematical constant recurring in analysis and number theory. It is defined as the limiting difference between the harmonic series and the natural logarithm: .. math:: \gamma = \lim\limits_{n\to\infty} \left(\sum\limits_{k=1}^n\frac{1}{k} - \ln n\right) EulerGamma is a singleton, and can be accessed by ``S.EulerGamma``. Examples ======== >>> from sympy import S >>> S.EulerGamma.is_irrational >>> S.EulerGamma > 0 True >>> S.EulerGamma > 1 False References ========== .. [1] https://en.wikipedia.org/wiki/Euler%E2%80%93Mascheroni_constant """ is_real = True is_positive = True is_negative = False is_irrational = None is_number = True __slots__ = [] def _latex(self, printer): return r"\gamma" def __int__(self): return 0 def _as_mpf_val(self, prec): # XXX track down why this has to be increased v = mlib.libhyper.euler_fixed(prec + 10) rv = mlib.from_man_exp(v, -prec - 10) return mpf_norm(rv, prec) def approximation_interval(self, number_cls): if issubclass(number_cls, Integer): return (S.Zero, S.One) elif issubclass(number_cls, Rational): return (S.Half, Rational(3, 5)) def _sage_(self): import sage.all as sage return sage.euler_gamma class Catalan(with_metaclass(Singleton, NumberSymbol)): r"""Catalan's constant. `K = 0.91596559\ldots` is given by the infinite series .. math:: K = \sum_{k=0}^{\infty} \frac{(-1)^k}{(2k+1)^2} Catalan is a singleton, and can be accessed by ``S.Catalan``. Examples ======== >>> from sympy import S >>> S.Catalan.is_irrational >>> S.Catalan > 0 True >>> S.Catalan > 1 False References ========== .. [1] https://en.wikipedia.org/wiki/Catalan%27s_constant """ is_real = True is_positive = True is_negative = False is_irrational = None is_number = True __slots__ = [] def __int__(self): return 0 def _as_mpf_val(self, prec): # XXX track down why this has to be increased v = mlib.catalan_fixed(prec + 10) rv = mlib.from_man_exp(v, -prec - 10) return mpf_norm(rv, prec) def approximation_interval(self, number_cls): if issubclass(number_cls, Integer): return (S.Zero, S.One) elif issubclass(number_cls, Rational): return (Rational(9, 10), S.One) def _sage_(self): import sage.all as sage return sage.catalan class ImaginaryUnit(with_metaclass(Singleton, AtomicExpr)): r"""The imaginary unit, `i = \sqrt{-1}`. I is a singleton, and can be accessed by ``S.I``, or can be imported as ``I``. Examples ======== >>> from sympy import I, sqrt >>> sqrt(-1) I >>> II -1 >>> 1/I -I References ========== .. [1] https://en.wikipedia.org/wiki/Imaginary_unit """ is_commutative = True is_imaginary = True is_finite = True is_number = True is_algebraic = True is_transcendental = False __slots__ = [] def _latex(self, printer): return r"i" @staticmethod def __abs__(): return S.One def _eval_evalf(self, prec): return self def _eval_conjugate(self): return -S.ImaginaryUnit def _eval_power(self, expt): """ b is I = sqrt(-1) e is symbolic object but not equal to 0, 1 Ir -> (-1)(r/2) -> exp(r/2PiI) -> sin(Pir/2) + cos(Pir/2)I, r is decimal I0 mod 4 -> 1 I1 mod 4 -> I I2 mod 4 -> -1 I3 mod 4 -> -I """ if isinstance(expt, Number): if isinstance(expt, Integer): expt = expt.p % 4 if expt == 0: return S.One if expt == 1: return S.ImaginaryUnit if expt == 2: return -S.One return -S.ImaginaryUnit return def as_base_exp(self): return S.NegativeOne, S.Half def _sage_(self): import sage.all as sage return sage.I @property def _mpc_(self): return (Float(0)._mpf_, Float(1)._mpf_) I = S.ImaginaryUnit def sympify_fractions(f): return Rational(f.numerator, f.denominator, 1) converter[fractions.Fraction] = sympify_fractions try: if HAS_GMPY == 2: import gmpy2 as gmpy elif HAS_GMPY == 1: import gmpy else: raise ImportError def sympify_mpz(x): return Integer(long(x)) def sympify_mpq(x): return Rational(long(x.numerator), long(x.denominator)) converter[type(gmpy.mpz(1))] = sympify_mpz converter[type(gmpy.mpq(1, 2))] = sympify_mpq except ImportError: pass def sympify_mpmath(x): return Expr._from_mpmath(x, x.context.prec) converter[mpnumeric] = sympify_mpmath def sympify_mpq(x): p, q = x._mpq_ return Rational(p, q, 1) converter[type(mpmath.rational.mpq(1, 2))] = sympify_mpq def sympify_complex(a): real, imag = list(map(sympify, (a.real, a.imag))) return real + S.ImaginaryUnit*imag converter[complex] = sympify_complex _intcache[0] = S.Zero _intcache[1] = S.One _intcache[-1] = S.NegativeOne from .power import Pow, integer_nthroot from .mul import Mul Mul.identity = One() from .add import Add Add.identity = Zero()
894eb3f15c93b0778af6259ba6b3a825257c6f502bf6483939e5cfb99f7e6342	from __future__ import print_function, division from sympy.core.sympify import _sympify, sympify from sympy.core.basic import Basic from sympy.core.cache import cacheit from sympy.core.compatibility import ordered, range from sympy.core.logic import fuzzy_and from sympy.core.evaluate import global_evaluate from sympy.utilities.iterables import sift class AssocOp(Basic): """ Associative operations, can separate noncommutative and commutative parts. (a op b) op c == a op (b op c) == a op b op c. Base class for Add and Mul. This is an abstract base class, concrete derived classes must define the attribute `identity`. """ # for performance reason, we don't let is_commutative go to assumptions, # and keep it right here __slots__ = ['is_commutative'] @cacheit def __new__(cls, args, options): from sympy import Order args = list(map(_sympify, args)) args = [a for a in args if a is not cls.identity] evaluate = options.get('evaluate') if evaluate is None: evaluate = global_evaluate[0] if not evaluate: return cls._from_args(args) if len(args) == 0: return cls.identity if len(args) == 1: return args[0] c_part, nc_part, order_symbols = cls.flatten(args) is_commutative = not nc_part obj = cls._from_args(c_part + nc_part, is_commutative) obj = cls._exec_constructor_postprocessors(obj) if order_symbols is not None: return Order(obj, order_symbols) return obj @classmethod def _from_args(cls, args, is_commutative=None): """Create new instance with already-processed args""" if len(args) == 0: return cls.identity elif len(args) == 1: return args[0] obj = super(AssocOp, cls).__new__(cls, args) if is_commutative is None: is_commutative = fuzzy_and(a.is_commutative for a in args) obj.is_commutative = is_commutative return obj def _new_rawargs(self, args, *kwargs): """Create new instance of own class with args exactly as provided by caller but returning the self class identity if args is empty. This is handy when we want to optimize things, e.g. >>> from sympy import Mul, S >>> from sympy.abc import x, y >>> e = Mul(3, x, y) >>> e.args (3, x, y) >>> Mul(e.args[1:]) xy >>> e._new_rawargs(e.args[1:]) # the same as above, but faster xy Note: use this with caution. There is no checking of arguments at all. This is best used when you are rebuilding an Add or Mul after simply removing one or more args. If, for example, modifications, result in extra 1s being inserted (as when collecting an expression's numerators and denominators) they will not show up in the result but a Mul will be returned nonetheless: >>> m = (xy)._new_rawargs(S.One, x); m x >>> m == x False >>> m.is_Mul True Another issue to be aware of is that the commutativity of the result is based on the commutativity of self. If you are rebuilding the terms that came from a commutative object then there will be no problem, but if self was non-commutative then what you are rebuilding may now be commutative. Although this routine tries to do as little as possible with the input, getting the commutativity right is important, so this level of safety is enforced: commutativity will always be recomputed if self is non-commutative and kwarg `reeval=False` has not been passed. """ if kwargs.pop('reeval', True) and self.is_commutative is False: is_commutative = None else: is_commutative = self.is_commutative return self._from_args(args, is_commutative) @classmethod def flatten(cls, seq): """Return seq so that none of the elements are of type `cls`. This is the vanilla routine that will be used if a class derived from AssocOp does not define its own flatten routine.""" # apply associativity, no commutativity property is used new_seq = [] while seq: o = seq.pop() if o.__class__ is cls: # classes must match exactly seq.extend(o.args) else: new_seq.append(o) # c_part, nc_part, order_symbols return [], new_seq, None def _matches_commutative(self, expr, repl_dict={}, old=False): """ Matches Add/Mul "pattern" to an expression "expr". repl_dict ... a dictionary of (wild: expression) pairs, that get returned with the results This function is the main workhorse for Add/Mul. For instance: >>> from sympy import symbols, Wild, sin >>> a = Wild("a") >>> b = Wild("b") >>> c = Wild("c") >>> x, y, z = symbols("x y z") >>> (a+sin(b)c)._matches_commutative(x+sin(y)z) {a_: x, b_: y, c_: z} In the example above, "a+sin(b)c" is the pattern, and "x+sin(y)z" is the expression. The repl_dict contains parts that were already matched. For example here: >>> (x+sin(b)c)._matches_commutative(x+sin(y)z, repl_dict={a: x}) {a_: x, b_: y, c_: z} the only function of the repl_dict is to return it in the result, e.g. if you omit it: >>> (x+sin(b)c)._matches_commutative(x+sin(y)z) {b_: y, c_: z} the "a: x" is not returned in the result, but otherwise it is equivalent. """ # make sure expr is Expr if pattern is Expr from .expr import Add, Expr from sympy import Mul if isinstance(self, Expr) and not isinstance(expr, Expr): return None # handle simple patterns if self == expr: return repl_dict d = self._matches_simple(expr, repl_dict) if d is not None: return d # eliminate exact part from pattern: (2+a+w1+w2).matches(expr) -> (w1+w2).matches(expr-a-2) from .function import WildFunction from .symbol import Wild wild_part, exact_part = sift(self.args, lambda p: p.has(Wild, WildFunction) and not expr.has(p), binary=True) if not exact_part: wild_part = list(ordered(wild_part)) else: exact = self._new_rawargs(exact_part) free = expr.free_symbols if free and (exact.free_symbols - free): # there are symbols in the exact part that are not # in the expr; but if there are no free symbols, let # the matching continue return None newexpr = self._combine_inverse(expr, exact) if not old and (expr.is_Add or expr.is_Mul): if newexpr.count_ops() > expr.count_ops(): return None newpattern = self._new_rawargs(wild_part) return newpattern.matches(newexpr, repl_dict) # now to real work ;) i = 0 saw = set() while expr not in saw: saw.add(expr) expr_list = (self.identity,) + tuple(ordered(self.make_args(expr))) for last_op in reversed(expr_list): for w in reversed(wild_part): d1 = w.matches(last_op, repl_dict) if d1 is not None: d2 = self.xreplace(d1).matches(expr, d1) if d2 is not None: return d2 if i == 0: if self.is_Mul: # make e*i look like Mul if expr.is_Pow and expr.exp.is_Integer: if expr.exp > 0: expr = Mul([expr.base, expr.base*(expr.exp - 1)], evaluate=False) else: expr = Mul([1/expr.base, expr.base*(expr.exp + 1)], evaluate=False) i += 1 continue elif self.is_Add: # make ie look like Add c, e = expr.as_coeff_Mul() if abs(c) > 1: if c > 0: expr = Add([e, (c - 1)e], evaluate=False) else: expr = Add([-e, (c + 1)e], evaluate=False) i += 1 continue # try collection on non-Wild symbols from sympy.simplify.radsimp import collect was = expr did = set() for w in reversed(wild_part): c, w = w.as_coeff_mul(Wild) free = c.free_symbols - did if free: did.update(free) expr = collect(expr, free) if expr != was: i += 0 continue break # if we didn't continue, there is nothing more to do return def _has_matcher(self): """Helper for .has()""" def _ncsplit(expr): # this is not the same as args_cnc because here # we don't assume expr is a Mul -- hence deal with args -- # and always return a set. cpart, ncpart = sift(expr.args, lambda arg: arg.is_commutative is True, binary=True) return set(cpart), ncpart c, nc = _ncsplit(self) cls = self.__class__ def is_in(expr): if expr == self: return True elif not isinstance(expr, Basic): return False elif isinstance(expr, cls): _c, _nc = _ncsplit(expr) if (c & _c) == c: if not nc: return True elif len(nc) <= len(_nc): for i in range(len(_nc) - len(nc) + 1): if _nc[i:i + len(nc)] == nc: return True return False return is_in def _eval_evalf(self, prec): """ Evaluate the parts of self that are numbers; if the whole thing was a number with no functions it would have been evaluated, but it wasn't so we must judiciously extract the numbers and reconstruct the object. This is not simply replacing numbers with evaluated numbers. Nunmbers should be handled in the largest pure-number expression as possible. So the code below separates ``self`` into number and non-number parts and evaluates the number parts and walks the args of the non-number part recursively (doing the same thing). """ from .add import Add from .mul import Mul from .symbol import Symbol from .function import AppliedUndef if isinstance(self, (Mul, Add)): x, tail = self.as_independent(Symbol, AppliedUndef) # if x is an AssocOp Function then the _evalf below will # call _eval_evalf (here) so we must break the recursion if not (tail is self.identity or isinstance(x, AssocOp) and x.is_Function or x is self.identity and isinstance(tail, AssocOp)): # here, we have a number so we just call to _evalf with prec; # prec is not the same as n, it is the binary precision so # that's why we don't call to evalf. x = x._evalf(prec) if x is not self.identity else self.identity args = [] tail_args = tuple(self.func.make_args(tail)) for a in tail_args: # here we call to _eval_evalf since we don't know what we # are dealing with and all other _eval_evalf routines should # be doing the same thing (i.e. taking binary prec and # finding the evalf-able args) newa = a._eval_evalf(prec) if newa is None: args.append(a) else: args.append(newa) return self.func(x, args) # this is the same as above, but there were no pure-number args to # deal with args = [] for a in self.args: newa = a._eval_evalf(prec) if newa is None: args.append(a) else: args.append(newa) return self.func(args) @classmethod def make_args(cls, expr): """ Return a sequence of elements `args` such that cls(args) == expr >>> from sympy import Symbol, Mul, Add >>> x, y = map(Symbol, 'xy') >>> Mul.make_args(xy) (x, y) >>> Add.make_args(xy) (xy,) >>> set(Add.make_args(xy + y)) == set([y, xy]) True """ if isinstance(expr, cls): return expr.args else: return (sympify(expr),) class ShortCircuit(Exception): pass class LatticeOp(AssocOp): """ Join/meet operations of an algebraic lattice[1]. These binary operations are associative (op(op(a, b), c) = op(a, op(b, c))), commutative (op(a, b) = op(b, a)) and idempotent (op(a, a) = op(a) = a). Common examples are AND, OR, Union, Intersection, max or min. They have an identity element (op(identity, a) = a) and an absorbing element conventionally called zero (op(zero, a) = zero). This is an abstract base class, concrete derived classes must declare attributes zero and identity. All defining properties are then respected. >>> from sympy import Integer >>> from sympy.core.operations import LatticeOp >>> class my_join(LatticeOp): ... zero = Integer(0) ... identity = Integer(1) >>> my_join(2, 3) == my_join(3, 2) True >>> my_join(2, my_join(3, 4)) == my_join(2, 3, 4) True >>> my_join(0, 1, 4, 2, 3, 4) 0 >>> my_join(1, 2) 2 References: [1] - https://en.wikipedia.org/wiki/Lattice_%28order%29 """ is_commutative = True def __new__(cls, args, options): args = (_sympify(arg) for arg in args) try: # /!\ args is a generator and _new_args_filter # must be careful to handle as such; this # is done so short-circuiting can be done # without having to sympify all values _args = frozenset(cls._new_args_filter(args)) except ShortCircuit: return sympify(cls.zero) if not _args: return sympify(cls.identity) elif len(_args) == 1: return set(_args).pop() else: # XXX in almost every other case for __new__, _args is # passed along, but the expectation here is for _args obj = super(AssocOp, cls).__new__(cls, _args) obj._argset = _args return obj @classmethod def _new_args_filter(cls, arg_sequence, call_cls=None): """Generator filtering args""" ncls = call_cls or cls for arg in arg_sequence: if arg == ncls.zero: raise ShortCircuit(arg) elif arg == ncls.identity: continue elif arg.func == ncls: for x in arg.args: yield x else: yield arg @classmethod def make_args(cls, expr): """ Return a set of args such that cls(*arg_set) == expr. """ if isinstance(expr, cls): return expr._argset else: return frozenset([sympify(expr)]) @property @cacheit def args(self): return tuple(ordered(self._argset)) @staticmethod def _compare_pretty(a, b): return (str(a) > str(b)) - (str(a) < str(b))
9506768d5435866ed41339a1c9fa63d259b6d06fb59b64b269678da529df165d	from __future__ import print_function from sympy.matrices.dense import MutableDenseMatrix from sympy.polys.polytools import Poly from sympy.polys.domains import EX class MutablePolyDenseMatrix(MutableDenseMatrix): """ A mutable matrix of objects from poly module or to operate with them. Examples ======== >>> from sympy.polys.polymatrix import PolyMatrix >>> from sympy import Symbol, Poly, ZZ >>> x = Symbol('x') >>> pm1 = PolyMatrix([[Poly(x2, x), Poly(-x, x)], [Poly(x3, x), Poly(-1 + x, x)]]) >>> v1 = PolyMatrix([[1, 0], [-1, 0]]) >>> pm1v1 Matrix([ [ Poly(x2 + x, x, domain='ZZ'), Poly(0, x, domain='ZZ')], [Poly(x3 - x + 1, x, domain='ZZ'), Poly(0, x, domain='ZZ')]]) >>> pm1.ring ZZ[x] >>> v1pm1 Matrix([ [ Poly(x2, x, domain='ZZ'), Poly(-x, x, domain='ZZ')], [Poly(-x2, x, domain='ZZ'), Poly(x, x, domain='ZZ')]]) >>> pm2 = PolyMatrix([[Poly(x2, x, domain='QQ'), Poly(0, x, domain='QQ'), Poly(1, x, domain='QQ'), \ Poly(x3, x, domain='QQ'), Poly(0, x, domain='QQ'), Poly(-x*3, x, domain='QQ')]]) >>> v2 = PolyMatrix([1, 0, 0, 0, 0, 0], ring=ZZ) >>> v2.ring ZZ >>> pm2v2 Matrix([[Poly(x*2, x, domain='QQ')]]) """ _class_priority = 10 # we don't want to sympify the elements of PolyMatrix _sympify = staticmethod(lambda x: x) def __init__(self, args, *kwargs): # if any non-Poly element is given as input then # 'ring' defaults 'EX' ring = kwargs.get('ring', EX) if all(isinstance(p, Poly) for p in self._mat) and self._mat: domain = tuple([p.domain[p.gens] for p in self._mat]) ring = domain[0] for i in range(1, len(domain)): ring = ring.unify(domain[i]) self.ring = ring def _eval_matrix_mul(self, other): self_rows, self_cols = self.rows, self.cols other_rows, other_cols = other.rows, other.cols other_len = other_rows other_cols new_mat_rows = self.rows new_mat_cols = other.cols new_mat = [0]new_mat_rowsnew_mat_cols if self.cols != 0 and other.rows != 0: mat = self._mat other_mat = other._mat for i in range(len(new_mat)): row, col = i // new_mat_cols, i % new_mat_cols row_indices = range(self_colsrow, self_cols(row+1)) col_indices = range(col, other_len, other_cols) vec = (mat[a]other_mat[b] for a,b in zip(row_indices, col_indices)) # 'Add' shouldn't be used here new_mat[i] = sum(vec) return self.__class__(new_mat_rows, new_mat_cols, new_mat, copy=False) def _eval_scalar_mul(self, other): mat = [Poly(a.as_expr()other, a.gens) if isinstance(a, Poly) else aother for a in self._mat] return self.__class__(self.rows, self.cols, mat, copy=False) def _eval_scalar_rmul(self, other): mat = [Poly(othera.as_expr(), a.gens) if isinstance(a, Poly) else other*a for a in self._mat] return self.__class__(self.rows, self.cols, mat, copy=False) MutablePolyMatrix = PolyMatrix = MutablePolyDenseMatrix
284208f19a492e41025933e38a7026df9291efc6edca22ac0659892b5f4ab8b2	"""Power series evaluation and manipulation using sparse Polynomials Implementing a new function --------------------------- There are a few things to be kept in mind when adding a new function here:: - The implementation should work on all possible input domains/rings. Special cases include the ``EX`` ring and a constant term in the series to be expanded. There can be two types of constant terms in the series: + A constant value or symbol. + A term of a multivariate series not involving the generator, with respect to which the series is to expanded. Strictly speaking, a generator of a ring should not be considered a constant. However, for series expansion both the cases need similar treatment (as the user doesn't care about inner details), i.e, use an addition formula to separate the constant part and the variable part (see rs_sin for reference). - All the algorithms used here are primarily designed to work for Taylor series (number of iterations in the algo equals the required order). Hence, it becomes tricky to get the series of the right order if a Puiseux series is input. Use rs_puiseux? in your function if your algorithm is not designed to handle fractional powers. Extending rs_series ------------------- To make a function work with rs_series you need to do two things:: - Many sure it works with a constant term (as explained above). - If the series contains constant terms, you might need to extend its ring. You do so by adding the new terms to the rings as generators. ``PolyRing.compose`` and ``PolyRing.add_gens`` are two functions that do so and need to be called every time you expand a series containing a constant term. Look at rs_sin and rs_series for further reference. """ from sympy.polys.domains import QQ, EX from sympy.polys.rings import PolyElement, ring, sring from sympy.polys.polyerrors import DomainError from sympy.polys.monomials import (monomial_min, monomial_mul, monomial_div, monomial_ldiv) from mpmath.libmp.libintmath import ifac from sympy.core import PoleError, Function, Expr from sympy.core.numbers import Rational, igcd from sympy.core.compatibility import as_int, range from sympy.functions import sin, cos, tan, atan, exp, atanh, tanh, log, ceiling from mpmath.libmp.libintmath import giant_steps import math def _invert_monoms(p1): """ Compute ``x*n p1(1/x)`` for a univariate polynomial ``p1`` in ``x``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import _invert_monoms >>> R, x = ring('x', ZZ) >>> p = x*2 + 2x + 3 >>> _invert_monoms(p) 3x2 + 2x + 1 See Also ======== sympy.polys.densebasic.dup_reverse """ terms = list(p1.items()) terms.sort() deg = p1.degree() R = p1.ring p = R.zero cv = p1.listcoeffs() mv = p1.listmonoms() for i in range(len(mv)): p[(deg - mv[i][0],)] = cv[i] return p def _giant_steps(target): """Return a list of precision steps for the Newton's method""" res = giant_steps(2, target) if res[0] != 2: res = [2] + res return res def rs_trunc(p1, x, prec): """ Truncate the series in the ``x`` variable with precision ``prec``, that is, modulo ``O(xprec)`` Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_trunc >>> R, x = ring('x', QQ) >>> p = x10 + x5 + x + 1 >>> rs_trunc(p, x, 12) x10 + x5 + x + 1 >>> rs_trunc(p, x, 10) x5 + x + 1 """ R = p1.ring p = R.zero i = R.gens.index(x) for exp1 in p1: if exp1[i] >= prec: continue p[exp1] = p1[exp1] return p def rs_is_puiseux(p, x): """ Test if ``p`` is Puiseux series in ``x``. Raise an exception if it has a negative power in ``x``. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_is_puiseux >>> R, x = ring('x', QQ) >>> p = xQQ(2,5) + xQQ(2,3) + x >>> rs_is_puiseux(p, x) True """ index = p.ring.gens.index(x) for k in p: if k[index] != int(k[index]): return True if k[index] < 0: raise ValueError('The series is not regular in %s' % x) return False def rs_puiseux(f, p, x, prec): """ Return the puiseux series for `f(p, x, prec)`. To be used when function ``f`` is implemented only for regular series. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_puiseux, rs_exp >>> R, x = ring('x', QQ) >>> p = xQQ(2,5) + xQQ(2,3) + x >>> rs_puiseux(rs_exp,p, x, 1) 1/2x(4/5) + x(2/3) + x(2/5) + 1 """ index = p.ring.gens.index(x) n = 1 for k in p: power = k[index] if isinstance(power, Rational): num, den = power.as_numer_denom() n = int(nden // igcd(n, den)) elif power != int(power): den = power.denominator n = int(nden // igcd(n, den)) if n != 1: p1 = pow_xin(p, index, n) r = f(p1, x, precn) n1 = QQ(1, n) if isinstance(r, tuple): r = tuple([pow_xin(rx, index, n1) for rx in r]) else: r = pow_xin(r, index, n1) else: r = f(p, x, prec) return r def rs_puiseux2(f, p, q, x, prec): """ Return the puiseux series for `f(p, q, x, prec)`. To be used when function ``f`` is implemented only for regular series. """ index = p.ring.gens.index(x) n = 1 for k in p: power = k[index] if isinstance(power, Rational): num, den = power.as_numer_denom() n = nden // igcd(n, den) elif power != int(power): den = power.denominator n = nden // igcd(n, den) if n != 1: p1 = pow_xin(p, index, n) r = f(p1, q, x, precn) n1 = QQ(1, n) r = pow_xin(r, index, n1) else: r = f(p, q, x, prec) return r def rs_mul(p1, p2, x, prec): """ Return the product of the given two series, modulo ``O(xprec)``. ``x`` is the series variable or its position in the generators. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_mul >>> R, x = ring('x', QQ) >>> p1 = x2 + 2x + 1 >>> p2 = x + 1 >>> rs_mul(p1, p2, x, 3) 3x2 + 3x + 1 """ R = p1.ring p = R.zero if R.__class__ != p2.ring.__class__ or R != p2.ring: raise ValueError('p1 and p2 must have the same ring') iv = R.gens.index(x) if not isinstance(p2, PolyElement): raise ValueError('p1 and p2 must have the same ring') if R == p2.ring: get = p.get items2 = list(p2.items()) items2.sort(key=lambda e: e[0][iv]) if R.ngens == 1: for exp1, v1 in p1.items(): for exp2, v2 in items2: exp = exp1[0] + exp2[0] if exp < prec: exp = (exp, ) p[exp] = get(exp, 0) + v1v2 else: break else: monomial_mul = R.monomial_mul for exp1, v1 in p1.items(): for exp2, v2 in items2: if exp1[iv] + exp2[iv] < prec: exp = monomial_mul(exp1, exp2) p[exp] = get(exp, 0) + v1v2 else: break p.strip_zero() return p def rs_square(p1, x, prec): """ Square the series modulo ``O(xprec)`` Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_square >>> R, x = ring('x', QQ) >>> p = x2 + 2x + 1 >>> rs_square(p, x, 3) 6x*2 + 4x + 1 """ R = p1.ring p = R.zero iv = R.gens.index(x) get = p.get items = list(p1.items()) items.sort(key=lambda e: e[0][iv]) monomial_mul = R.monomial_mul for i in range(len(items)): exp1, v1 = items[i] for j in range(i): exp2, v2 = items[j] if exp1[iv] + exp2[iv] < prec: exp = monomial_mul(exp1, exp2) p[exp] = get(exp, 0) + v1v2 else: break p = p.imul_num(2) get = p.get for expv, v in p1.items(): if 2expv[iv] < prec: e2 = monomial_mul(expv, expv) p[e2] = get(e2, 0) + v2 p.strip_zero() return p def rs_pow(p1, n, x, prec): """ Return ``p1n`` modulo ``O(x*prec)`` Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_pow >>> R, x = ring('x', QQ) >>> p = x + 1 >>> rs_pow(p, 4, x, 3) 6x*2 + 4x + 1 """ R = p1.ring p = R.zero if isinstance(n, Rational): np = int(n.p) nq = int(n.q) if nq != 1: res = rs_nth_root(p1, nq, x, prec) if np != 1: res = rs_pow(res, np, x, prec) else: res = rs_pow(p1, np, x, prec) return res n = as_int(n) if n == 0: if p1: return R(1) else: raise ValueError('00 is undefined') if n < 0: p1 = rs_pow(p1, -n, x, prec) return rs_series_inversion(p1, x, prec) if n == 1: return rs_trunc(p1, x, prec) if n == 2: return rs_square(p1, x, prec) if n == 3: p2 = rs_square(p1, x, prec) return rs_mul(p1, p2, x, prec) p = R(1) while 1: if n & 1: p = rs_mul(p1, p, x, prec) n -= 1 if not n: break p1 = rs_square(p1, x, prec) n = n // 2 return p def rs_subs(p, rules, x, prec): """ Substitution with truncation according to the mapping in ``rules``. Return a series with precision ``prec`` in the generator ``x`` Note that substitutions are not done one after the other >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_subs >>> R, x, y = ring('x, y', QQ) >>> p = x2 + y*2 >>> rs_subs(p, {x: x+ y, y: x+ 2y}, x, 3) 2x2 + 6xy + 5y2 >>> (x + y)2 + (x + 2y)2 2x*2 + 6xy + 5y*2 which differs from >>> rs_subs(rs_subs(p, {x: x+ y}, x, 3), {y: x+ 2y}, x, 3) 5x2 + 12xy + 8y2 Parameters ---------- p : :class:`PolyElement` Input series. rules : :class:`dict` with substitution mappings. x : :class:`PolyElement` in which the series truncation is to be done. prec : :class:`Integer` order of the series after truncation. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_subs >>> R, x, y = ring('x, y', QQ) >>> rs_subs(x2+y2, {y: (x+y)2}, x, 3) 6x2y2 + x2 + 4xy3 + y4 """ R = p.ring ngens = R.ngens d = R(0) for i in range(ngens): d[(i, 1)] = R.gens[i] for var in rules: d[(R.index(var), 1)] = rules[var] p1 = R(0) p_keys = sorted(p.keys()) for expv in p_keys: p2 = R(1) for i in range(ngens): power = expv[i] if power == 0: continue if (i, power) not in d: q, r = divmod(power, 2) if r == 0 and (i, q) in d: d[(i, power)] = rs_square(d[(i, q)], x, prec) elif (i, power - 1) in d: d[(i, power)] = rs_mul(d[(i, power - 1)], d[(i, 1)], x, prec) else: d[(i, power)] = rs_pow(d[(i, 1)], power, x, prec) p2 = rs_mul(p2, d[(i, power)], x, prec) p1 += p2p[expv] return p1 def _has_constant_term(p, x): """ Check if ``p`` has a constant term in ``x`` Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import _has_constant_term >>> R, x = ring('x', QQ) >>> p = x2 + x + 1 >>> _has_constant_term(p, x) True """ R = p.ring iv = R.gens.index(x) zm = R.zero_monom a = [0]R.ngens a[iv] = 1 miv = tuple(a) for expv in p: if monomial_min(expv, miv) == zm: return True return False def _get_constant_term(p, x): """Return constant term in p with respect to x Note that it is not simply `p[R.zero_monom]` as there might be multiple generators in the ring R. We want the `x`-free term which can contain other generators. """ R = p.ring zm = R.zero_monom i = R.gens.index(x) zm = R.zero_monom a = [0]R.ngens a[i] = 1 miv = tuple(a) c = 0 for expv in p: if monomial_min(expv, miv) == zm: c += R({expv: p[expv]}) return c def _check_series_var(p, x, name): index = p.ring.gens.index(x) m = min(p, key=lambda k: k[index])[index] if m < 0: raise PoleError("Asymptotic expansion of %s around [oo] not " "implemented." % name) return index, m def _series_inversion1(p, x, prec): """ Univariate series inversion ``1/p`` modulo ``O(xprec)``. The Newton method is used. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import _series_inversion1 >>> R, x = ring('x', QQ) >>> p = x + 1 >>> _series_inversion1(p, x, 4) -x3 + x2 - x + 1 """ if rs_is_puiseux(p, x): return rs_puiseux(_series_inversion1, p, x, prec) R = p.ring zm = R.zero_monom c = p[zm] # giant_steps does not seem to work with PythonRational numbers with 1 as # denominator. This makes sure such a number is converted to integer. if prec == int(prec): prec = int(prec) if zm not in p: raise ValueError("No constant term in series") if _has_constant_term(p - c, x): raise ValueError("p cannot contain a constant term depending on " "parameters") one = R(1) if R.domain is EX: one = 1 if c != one: # TODO add check that it is a unit p1 = R(1)/c else: p1 = R(1) for precx in _giant_steps(prec): t = 1 - rs_mul(p1, p, x, precx) p1 = p1 + rs_mul(p1, t, x, precx) return p1 def rs_series_inversion(p, x, prec): """ Multivariate series inversion ``1/p`` modulo ``O(xprec)``. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_series_inversion >>> R, x, y = ring('x, y', QQ) >>> rs_series_inversion(1 + xy2, x, 4) -x3y6 + x2y*4 - xy*2 + 1 >>> rs_series_inversion(1 + xy*2, y, 4) -xy2 + 1 >>> rs_series_inversion(x + x2, x, 4) x3 - x2 + x - 1 + x(-1) """ R = p.ring if p == R.zero: raise ZeroDivisionError zm = R.zero_monom index = R.gens.index(x) m = min(p, key=lambda k: k[index])[index] if m: p = mul_xin(p, index, -m) prec = prec + m if zm not in p: raise NotImplementedError("No constant term in series") if _has_constant_term(p - p[zm], x): raise NotImplementedError("p - p[0] must not have a constant term in " "the series variables") r = _series_inversion1(p, x, prec) if m != 0: r = mul_xin(r, index, -m) return r def _coefficient_t(p, t): r"""Coefficient of `x\_ij` in p, where ``t`` = (i, j)""" i, j = t R = p.ring expv1 = [0]R.ngens expv1[i] = j expv1 = tuple(expv1) p1 = R(0) for expv in p: if expv[i] == j: p1[monomial_div(expv, expv1)] = p[expv] return p1 def rs_series_reversion(p, x, n, y): r""" Reversion of a series. ``p`` is a series with ``O(xn)`` of the form `p = ax + f(x)` where `a` is a number different from 0. `f(x) = sum( a\_kx\_k, k in range(2, n))` a_k : Can depend polynomially on other variables, not indicated. x : Variable with name x. y : Variable with name y. Solve `p = y`, that is, given `ax + f(x) - y = 0`, find the solution x = r(y) up to O(y*n) Algorithm: If `r\_i` is the solution at order i, then: `ar\_i + f(r\_i) - y = O(y*(i + 1))` and if r_(i + 1) is the solution at order i + 1, then: `ar\_(i + 1) + f(r\_(i + 1)) - y = O(y*(i + 2))` We have, r_(i + 1) = r_i + e, such that, `ae + f(r\_i) = O(y(i + 2))` or `e = -f(r\_i)/a` So we use the recursion relation: `r\_(i + 1) = r\_i - f(r\_i)/a` with the boundary condition: `r\_1 = y` Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_series_reversion, rs_trunc >>> R, x, y, a, b = ring('x, y, a, b', QQ) >>> p = x - x2 - 2bx*2 + 2abx*2 >>> p1 = rs_series_reversion(p, x, 3, y); p1 -2y*2ab + 2y*2b + y*2 + y >>> rs_trunc(p.compose(x, p1), y, 3) y """ if rs_is_puiseux(p, x): raise NotImplementedError R = p.ring nx = R.gens.index(x) y = R(y) ny = R.gens.index(y) if _has_constant_term(p, x): raise ValueError("p must not contain a constant term in the series " "variable") a = _coefficient_t(p, (nx, 1)) zm = R.zero_monom assert zm in a and len(a) == 1 a = a[zm] r = y/a for i in range(2, n): sp = rs_subs(p, {x: r}, y, i + 1) sp = _coefficient_t(sp, (ny, i))y*i r -= sp/a return r def rs_series_from_list(p, c, x, prec, concur=1): """ Return a series `sum c[n]pn` modulo `O(xprec)`. It reduces the number of multiplications by summing concurrently. `ax = [1, p, p2, .., p(J - 1)]` `s = sum(c[i]ax[i]` for i in `range(r, (r + 1)J))p((K - 1)J)` with `K >= (n + 1)/J` Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_series_from_list, rs_trunc >>> R, x = ring('x', QQ) >>> p = x*2 + x + 1 >>> c = [1, 2, 3] >>> rs_series_from_list(p, c, x, 4) 6x*3 + 11x*2 + 8x + 6 >>> rs_trunc(1 + 2p + 3p*2, x, 4) 6x*3 + 11x*2 + 8x + 6 >>> pc = R.from_list(list(reversed(c))) >>> rs_trunc(pc.compose(x, p), x, 4) 6x3 + 11x*2 + 8x + 6 See Also ======== sympy.polys.ring.compose """ R = p.ring n = len(c) if not concur: q = R(1) s = c[0]q for i in range(1, n): q = rs_mul(q, p, x, prec) s += c[i]q return s J = int(math.sqrt(n) + 1) K, r = divmod(n, J) if r: K += 1 ax = [R(1)] b = 1 q = R(1) if len(p) < 20: for i in range(1, J): q = rs_mul(q, p, x, prec) ax.append(q) else: for i in range(1, J): if i % 2 == 0: q = rs_square(ax[i//2], x, prec) else: q = rs_mul(q, p, x, prec) ax.append(q) # optimize using rs_square pj = rs_mul(ax[-1], p, x, prec) b = R(1) s = R(0) for k in range(K - 1): r = Jk s1 = c[r] for j in range(1, J): s1 += c[r + j]ax[j] s1 = rs_mul(s1, b, x, prec) s += s1 b = rs_mul(b, pj, x, prec) if not b: break k = K - 1 r = Jk if r < n: s1 = c[r]R(1) for j in range(1, J): if r + j >= n: break s1 += c[r + j]ax[j] s1 = rs_mul(s1, b, x, prec) s += s1 return s def rs_diff(p, x): """ Return partial derivative of ``p`` with respect to ``x``. Parameters ========== x : :class:`PolyElement` with respect to which ``p`` is differentiated. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_diff >>> R, x, y = ring('x, y', QQ) >>> p = x + x2y*3 >>> rs_diff(p, x) 2xy3 + 1 """ R = p.ring n = R.gens.index(x) p1 = R.zero mn = [0]R.ngens mn[n] = 1 mn = tuple(mn) for expv in p: if expv[n]: e = monomial_ldiv(expv, mn) p1[e] = R.domain_new(p[expv]expv[n]) return p1 def rs_integrate(p, x): """ Integrate ``p`` with respect to ``x``. Parameters ========== x : :class:`PolyElement` with respect to which ``p`` is integrated. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_integrate >>> R, x, y = ring('x, y', QQ) >>> p = x + x2y*3 >>> rs_integrate(p, x) 1/3x*3y*3 + 1/2x*2 """ R = p.ring p1 = R.zero n = R.gens.index(x) mn = [0]R.ngens mn[n] = 1 mn = tuple(mn) for expv in p: e = monomial_mul(expv, mn) p1[e] = R.domain_new(p[expv]/(expv[n] + 1)) return p1 def rs_fun(p, f, args): r""" Function of a multivariate series computed by substitution. The case with f method name is used to compute `rs\_tan` and `rs\_nth\_root` of a multivariate series: `rs\_fun(p, tan, iv, prec)` tan series is first computed for a dummy variable _x, i.e, `rs\_tan(\_x, iv, prec)`. Then we substitute _x with p to get the desired series Parameters ========== p : :class:`PolyElement` The multivariate series to be expanded. f : `ring\_series` function to be applied on `p`. args[-2] : :class:`PolyElement` with respect to which, the series is to be expanded. args[-1] : Required order of the expanded series. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_fun, _tan1 >>> R, x, y = ring('x, y', QQ) >>> p = x + xy + x*2y + x*3y*2 >>> rs_fun(p, _tan1, x, 4) 1/3x*3y*3 + 2x*3y2 + x3y + 1/3x3 + x2y + xy + x """ _R = p.ring R1, _x = ring('_x', _R.domain) h = int(args[-1]) args1 = args[:-2] + (_x, h) zm = _R.zero_monom # separate the constant term of the series # compute the univariate series f(_x, .., 'x', sum(nv)) if zm in p: x1 = _x + p[zm] p1 = p - p[zm] else: x1 = _x p1 = p if isinstance(f, str): q = getattr(x1, f)(args1) else: q = f(x1, args1) a = sorted(q.items()) c = [0]h for x in a: c[x[0][0]] = x[1] p1 = rs_series_from_list(p1, c, args[-2], args[-1]) return p1 def mul_xin(p, i, n): r""" Return `px_in`. `x\_i` is the ith variable in ``p``. """ R = p.ring q = R(0) for k, v in p.items(): k1 = list(k) k1[i] += n q[tuple(k1)] = v return q def pow_xin(p, i, n): """ >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import pow_xin >>> R, x, y = ring('x, y', QQ) >>> p = xQQ(2,5) + x + xQQ(2,3) >>> index = p.ring.gens.index(x) >>> pow_xin(p, index, 15) x15 + x10 + x6 """ R = p.ring q = R(0) for k, v in p.items(): k1 = list(k) k1[i] = n q[tuple(k1)] = v return q def _nth_root1(p, n, x, prec): """ Univariate series expansion of the nth root of ``p``. The Newton method is used. """ if rs_is_puiseux(p, x): return rs_puiseux2(_nth_root1, p, n, x, prec) R = p.ring zm = R.zero_monom if zm not in p: raise NotImplementedError('No constant term in series') n = as_int(n) assert p[zm] == 1 p1 = R(1) if p == 1: return p if n == 0: return R(1) if n == 1: return p if n < 0: n = -n sign = 1 else: sign = 0 for precx in _giant_steps(prec): tmp = rs_pow(p1, n + 1, x, precx) tmp = rs_mul(tmp, p, x, precx) p1 += p1/n - tmp/n if sign: return p1 else: return _series_inversion1(p1, x, prec) def rs_nth_root(p, n, x, prec): """ Multivariate series expansion of the nth root of ``p``. Parameters ========== p : Expr The polynomial to computer the root of. n : integer The order of the root to be computed. x : :class:`PolyElement` prec : integer Order of the expanded series. Notes ===== The result of this function is dependent on the ring over which the polynomial has been defined. If the answer involves a root of a constant, make sure that the polynomial is over a real field. It can not yet handle roots of symbols. Examples ======== >>> from sympy.polys.domains import QQ, RR >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_nth_root >>> R, x, y = ring('x, y', QQ) >>> rs_nth_root(1 + x + xy, -3, x, 3) 2/9x2y*2 + 4/9x*2y + 2/9x2 - 1/3xy - 1/3x + 1 >>> R, x, y = ring('x, y', RR) >>> rs_nth_root(3 + x + xy, 3, x, 2) 0.160249952256379xy + 0.160249952256379x + 1.44224957030741 """ p0 = p n0 = n if n == 0: if p == 0: raise ValueError('00 expression') else: return p.ring(1) if n == 1: return rs_trunc(p, x, prec) R = p.ring zm = R.zero_monom index = R.gens.index(x) m = min(p, key=lambda k: k[index])[index] p = mul_xin(p, index, -m) prec -= m if _has_constant_term(p - 1, x): zm = R.zero_monom c = p[zm] if R.domain is EX: c_expr = c.as_expr() const = c_exprQQ(1, n) elif isinstance(c, PolyElement): try: c_expr = c.as_expr() const = R(c_expr(QQ(1, n))) except ValueError: raise DomainError("The given series can't be expanded in " "this domain.") else: try: # RealElement doesn't support const = R(cRational(1, n)) # exponentiation with mpq object except ValueError: # as exponent raise DomainError("The given series can't be expanded in " "this domain.") res = rs_nth_root(p/c, n, x, prec)const else: res = _nth_root1(p, n, x, prec) if m: m = QQ(m, n) res = mul_xin(res, index, m) return res def rs_log(p, x, prec): """ The Logarithm of ``p`` modulo ``O(xprec)``. Notes ===== Truncation of ``integral dx p-1d p/dx`` is used. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_log >>> R, x = ring('x', QQ) >>> rs_log(1 + x, x, 8) 1/7x7 - 1/6x*6 + 1/5x*5 - 1/4x*4 + 1/3x*3 - 1/2x2 + x >>> rs_log(xQQ(3, 2) + 1, x, 5) 1/3x(9/2) - 1/2x3 + x(3/2) """ if rs_is_puiseux(p, x): return rs_puiseux(rs_log, p, x, prec) R = p.ring if p == 1: return R.zero c = _get_constant_term(p, x) if c: const = 0 if c == 1: pass else: c_expr = c.as_expr() if R.domain is EX: const = log(c_expr) elif isinstance(c, PolyElement): try: const = R(log(c_expr)) except ValueError: R = R.add_gens([log(c_expr)]) p = p.set_ring(R) x = x.set_ring(R) c = c.set_ring(R) const = R(log(c_expr)) else: try: const = R(log(c)) except ValueError: raise DomainError("The given series can't be expanded in " "this domain.") dlog = p.diff(x) dlog = rs_mul(dlog, _series_inversion1(p, x, prec), x, prec - 1) return rs_integrate(dlog, x) + const else: raise NotImplementedError def rs_LambertW(p, x, prec): """ Calculate the series expansion of the principal branch of the Lambert W function. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_LambertW >>> R, x, y = ring('x, y', QQ) >>> rs_LambertW(x + xy, x, 3) -x2y*2 - 2x*2y - x*2 + xy + x See Also ======== LambertW """ if rs_is_puiseux(p, x): return rs_puiseux(rs_LambertW, p, x, prec) R = p.ring p1 = R(0) if _has_constant_term(p, x): raise NotImplementedError("Polynomial must not have constant term in " "the series variables") if x in R.gens: for precx in _giant_steps(prec): e = rs_exp(p1, x, precx) p2 = rs_mul(e, p1, x, precx) - p p3 = rs_mul(e, p1 + 1, x, precx) p3 = rs_series_inversion(p3, x, precx) tmp = rs_mul(p2, p3, x, precx) p1 -= tmp return p1 else: raise NotImplementedError def _exp1(p, x, prec): r"""Helper function for `rs\_exp`. """ R = p.ring p1 = R(1) for precx in _giant_steps(prec): pt = p - rs_log(p1, x, precx) tmp = rs_mul(pt, p1, x, precx) p1 += tmp return p1 def rs_exp(p, x, prec): """ Exponentiation of a series modulo ``O(xprec)`` Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_exp >>> R, x = ring('x', QQ) >>> rs_exp(x2, x, 7) 1/6x6 + 1/2x4 + x2 + 1 """ if rs_is_puiseux(p, x): return rs_puiseux(rs_exp, p, x, prec) R = p.ring c = _get_constant_term(p, x) if c: if R.domain is EX: c_expr = c.as_expr() const = exp(c_expr) elif isinstance(c, PolyElement): try: c_expr = c.as_expr() const = R(exp(c_expr)) except ValueError: R = R.add_gens([exp(c_expr)]) p = p.set_ring(R) x = x.set_ring(R) c = c.set_ring(R) const = R(exp(c_expr)) else: try: const = R(exp(c)) except ValueError: raise DomainError("The given series can't be expanded in " "this domain.") p1 = p - c # Makes use of sympy functions to evaluate the values of the cos/sin # of the constant term. return constrs_exp(p1, x, prec) if len(p) > 20: return _exp1(p, x, prec) one = R(1) n = 1 k = 1 c = [] for k in range(prec): c.append(one/n) k += 1 n = k r = rs_series_from_list(p, c, x, prec) return r def _atan(p, iv, prec): """ Expansion using formula. Faster on very small and univariate series. """ R = p.ring mo = R(-1) c = [-mo] p2 = rs_square(p, iv, prec) for k in range(1, prec): c.append(mo*k/(2k + 1)) s = rs_series_from_list(p2, c, iv, prec) s = rs_mul(s, p, iv, prec) return s def rs_atan(p, x, prec): """ The arctangent of a series Return the series expansion of the atan of ``p``, about 0. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_atan >>> R, x, y = ring('x, y', QQ) >>> rs_atan(x + xy, x, 4) -1/3x*3y3 - x3y2 - x3y - 1/3x3 + xy + x See Also ======== atan """ if rs_is_puiseux(p, x): return rs_puiseux(rs_atan, p, x, prec) R = p.ring const = 0 if _has_constant_term(p, x): zm = R.zero_monom c = p[zm] if R.domain is EX: c_expr = c.as_expr() const = atan(c_expr) elif isinstance(c, PolyElement): try: c_expr = c.as_expr() const = R(atan(c_expr)) except ValueError: raise DomainError("The given series can't be expanded in " "this domain.") else: try: const = R(atan(c)) except ValueError: raise DomainError("The given series can't be expanded in " "this domain.") # Instead of using a closed form formula, we differentiate atan(p) to get # `1/(1+p*2) dp`, whose series expansion is much easier to calculate. # Finally we integrate to get back atan dp = p.diff(x) p1 = rs_square(p, x, prec) + R(1) p1 = rs_series_inversion(p1, x, prec - 1) p1 = rs_mul(dp, p1, x, prec - 1) return rs_integrate(p1, x) + const def rs_asin(p, x, prec): """ Arcsine of a series Return the series expansion of the asin of ``p``, about 0. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_asin >>> R, x, y = ring('x, y', QQ) >>> rs_asin(x, x, 8) 5/112x7 + 3/40x*5 + 1/6x3 + x See Also ======== asin """ if rs_is_puiseux(p, x): return rs_puiseux(rs_asin, p, x, prec) if _has_constant_term(p, x): raise NotImplementedError("Polynomial must not have constant term in " "series variables") R = p.ring if x in R.gens: # get a good value if len(p) > 20: dp = rs_diff(p, x) p1 = 1 - rs_square(p, x, prec - 1) p1 = rs_nth_root(p1, -2, x, prec - 1) p1 = rs_mul(dp, p1, x, prec - 1) return rs_integrate(p1, x) one = R(1) c = [0, one, 0] for k in range(3, prec, 2): c.append((k - 2)2c[-2]/(k(k - 1))) c.append(0) return rs_series_from_list(p, c, x, prec) else: raise NotImplementedError def _tan1(p, x, prec): r""" Helper function of `rs\_tan`. Return the series expansion of tan of a univariate series using Newton's method. It takes advantage of the fact that series expansion of atan is easier than that of tan. Consider `f(x) = y - atan(x)` Let r be a root of f(x) found using Newton's method. Then `f(r) = 0` Or `y = atan(x)` where `x = tan(y)` as required. """ R = p.ring p1 = R(0) for precx in _giant_steps(prec): tmp = p - rs_atan(p1, x, precx) tmp = rs_mul(tmp, 1 + rs_square(p1, x, precx), x, precx) p1 += tmp return p1 def rs_tan(p, x, prec): """ Tangent of a series. Return the series expansion of the tan of ``p``, about 0. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_tan >>> R, x, y = ring('x, y', QQ) >>> rs_tan(x + xy, x, 4) 1/3x*3y3 + x3y2 + x3y + 1/3x3 + xy + x See Also ======== _tan1, tan """ if rs_is_puiseux(p, x): r = rs_puiseux(rs_tan, p, x, prec) return r R = p.ring const = 0 c = _get_constant_term(p, x) if c: if R.domain is EX: c_expr = c.as_expr() const = tan(c_expr) elif isinstance(c, PolyElement): try: c_expr = c.as_expr() const = R(tan(c_expr)) except ValueError: R = R.add_gens([tan(c_expr, )]) p = p.set_ring(R) x = x.set_ring(R) c = c.set_ring(R) const = R(tan(c_expr)) else: try: const = R(tan(c)) except ValueError: raise DomainError("The given series can't be expanded in " "this domain.") p1 = p - c # Makes use of sympy functions to evaluate the values of the cos/sin # of the constant term. t2 = rs_tan(p1, x, prec) t = rs_series_inversion(1 - constt2, x, prec) return rs_mul(const + t2, t, x, prec) if R.ngens == 1: return _tan1(p, x, prec) else: return rs_fun(p, rs_tan, x, prec) def rs_cot(p, x, prec): """ Cotangent of a series Return the series expansion of the cot of ``p``, about 0. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_cot >>> R, x, y = ring('x, y', QQ) >>> rs_cot(x, x, 6) -2/945x*5 - 1/45x*3 - 1/3x + x*(-1) See Also ======== cot """ # It can not handle series like `p = x + xy` where the coefficient of the # linear term in the series variable is symbolic. if rs_is_puiseux(p, x): r = rs_puiseux(rs_cot, p, x, prec) return r i, m = _check_series_var(p, x, 'cot') prec1 = prec + 2m c, s = rs_cos_sin(p, x, prec1) s = mul_xin(s, i, -m) s = rs_series_inversion(s, x, prec1) res = rs_mul(c, s, x, prec1) res = mul_xin(res, i, -m) res = rs_trunc(res, x, prec) return res def rs_sin(p, x, prec): """ Sine of a series Return the series expansion of the sin of ``p``, about 0. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_sin >>> R, x, y = ring('x, y', QQ) >>> rs_sin(x + xy, x, 4) -1/6x3y*3 - 1/2x*3y*2 - 1/2x*3y - 1/6x3 + xy + x >>> rs_sin(x*QQ(3, 2) + xy*QQ(7, 5), x, 4) -1/2x*(7/2)y*(14/5) - 1/6x*3y(21/5) + x(3/2) + xy(7/5) See Also ======== sin """ if rs_is_puiseux(p, x): return rs_puiseux(rs_sin, p, x, prec) R = x.ring if not p: return R(0) c = _get_constant_term(p, x) if c: if R.domain is EX: c_expr = c.as_expr() t1, t2 = sin(c_expr), cos(c_expr) elif isinstance(c, PolyElement): try: c_expr = c.as_expr() t1, t2 = R(sin(c_expr)), R(cos(c_expr)) except ValueError: R = R.add_gens([sin(c_expr), cos(c_expr)]) p = p.set_ring(R) x = x.set_ring(R) c = c.set_ring(R) t1, t2 = R(sin(c_expr)), R(cos(c_expr)) else: try: t1, t2 = R(sin(c)), R(cos(c)) except ValueError: raise DomainError("The given series can't be expanded in " "this domain.") p1 = p - c # Makes use of sympy cos, sin functions to evaluate the values of the # cos/sin of the constant term. return rs_sin(p1, x, prec)t2 + rs_cos(p1, x, prec)t1 # Series is calculated in terms of tan as its evaluation is fast. if len(p) > 20 and R.ngens == 1: t = rs_tan(p/2, x, prec) t2 = rs_square(t, x, prec) p1 = rs_series_inversion(1 + t2, x, prec) return rs_mul(p1, 2t, x, prec) one = R(1) n = 1 c = [0] for k in range(2, prec + 2, 2): c.append(one/n) c.append(0) n = -k(k + 1) return rs_series_from_list(p, c, x, prec) def rs_cos(p, x, prec): """ Cosine of a series Return the series expansion of the cos of ``p``, about 0. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_cos >>> R, x, y = ring('x, y', QQ) >>> rs_cos(x + xy, x, 4) -1/2x*2y2 - x2y - 1/2x*2 + 1 >>> rs_cos(x + xy, x, 4)/x*QQ(7, 5) -1/2x*(3/5)y2 - x(3/5)y - 1/2x(3/5) + x(-7/5) See Also ======== cos """ if rs_is_puiseux(p, x): return rs_puiseux(rs_cos, p, x, prec) R = p.ring c = _get_constant_term(p, x) if c: if R.domain is EX: c_expr = c.as_expr() t1, t2 = sin(c_expr), cos(c_expr) elif isinstance(c, PolyElement): try: c_expr = c.as_expr() t1, t2 = R(sin(c_expr)), R(cos(c_expr)) except ValueError: R = R.add_gens([sin(c_expr), cos(c_expr)]) p = p.set_ring(R) x = x.set_ring(R) c = c.set_ring(R) else: try: t1, t2 = R(sin(c)), R(cos(c)) except ValueError: raise DomainError("The given series can't be expanded in " "this domain.") p1 = p - c # Makes use of sympy cos, sin functions to evaluate the values of the # cos/sin of the constant term. p_cos = rs_cos(p1, x, prec) p_sin = rs_sin(p1, x, prec) R = R.compose(p_cos.ring).compose(p_sin.ring) p_cos.set_ring(R) p_sin.set_ring(R) t1, t2 = R(sin(c_expr)), R(cos(c_expr)) return p_cost2 - p_sint1 # Series is calculated in terms of tan as its evaluation is fast. if len(p) > 20 and R.ngens == 1: t = rs_tan(p/2, x, prec) t2 = rs_square(t, x, prec) p1 = rs_series_inversion(1+t2, x, prec) return rs_mul(p1, 1 - t2, x, prec) one = R(1) n = 1 c = [] for k in range(2, prec + 2, 2): c.append(one/n) c.append(0) n = -k(k - 1) return rs_series_from_list(p, c, x, prec) def rs_cos_sin(p, x, prec): r""" Return the tuple `(rs\_cos(p, x, prec)`, `rs\_sin(p, x, prec))`. Is faster than calling rs_cos and rs_sin separately """ if rs_is_puiseux(p, x): return rs_puiseux(rs_cos_sin, p, x, prec) t = rs_tan(p/2, x, prec) t2 = rs_square(t, x, prec) p1 = rs_series_inversion(1 + t2, x, prec) return (rs_mul(p1, 1 - t2, x, prec), rs_mul(p1, 2t, x, prec)) def _atanh(p, x, prec): """ Expansion using formula Faster for very small and univariate series """ R = p.ring one = R(1) c = [one] p2 = rs_square(p, x, prec) for k in range(1, prec): c.append(one/(2k + 1)) s = rs_series_from_list(p2, c, x, prec) s = rs_mul(s, p, x, prec) return s def rs_atanh(p, x, prec): """ Hyperbolic arctangent of a series Return the series expansion of the atanh of ``p``, about 0. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_atanh >>> R, x, y = ring('x, y', QQ) >>> rs_atanh(x + xy, x, 4) 1/3x*3y3 + x3y2 + x3y + 1/3x3 + xy + x See Also ======== atanh """ if rs_is_puiseux(p, x): return rs_puiseux(rs_atanh, p, x, prec) R = p.ring const = 0 if _has_constant_term(p, x): zm = R.zero_monom c = p[zm] if R.domain is EX: c_expr = c.as_expr() const = atanh(c_expr) elif isinstance(c, PolyElement): try: c_expr = c.as_expr() const = R(atanh(c_expr)) except ValueError: raise DomainError("The given series can't be expanded in " "this domain.") else: try: const = R(atanh(c)) except ValueError: raise DomainError("The given series can't be expanded in " "this domain.") # Instead of using a closed form formula, we differentiate atanh(p) to get # `1/(1-p*2) dp`, whose series expansion is much easier to calculate. # Finally we integrate to get back atanh dp = rs_diff(p, x) p1 = - rs_square(p, x, prec) + 1 p1 = rs_series_inversion(p1, x, prec - 1) p1 = rs_mul(dp, p1, x, prec - 1) return rs_integrate(p1, x) + const def rs_sinh(p, x, prec): """ Hyperbolic sine of a series Return the series expansion of the sinh of ``p``, about 0. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_sinh >>> R, x, y = ring('x, y', QQ) >>> rs_sinh(x + xy, x, 4) 1/6x*3y*3 + 1/2x*3y*2 + 1/2x*3y + 1/6x3 + xy + x See Also ======== sinh """ if rs_is_puiseux(p, x): return rs_puiseux(rs_sinh, p, x, prec) t = rs_exp(p, x, prec) t1 = rs_series_inversion(t, x, prec) return (t - t1)/2 def rs_cosh(p, x, prec): """ Hyperbolic cosine of a series Return the series expansion of the cosh of ``p``, about 0. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_cosh >>> R, x, y = ring('x, y', QQ) >>> rs_cosh(x + xy, x, 4) 1/2x*2y2 + x2y + 1/2x*2 + 1 See Also ======== cosh """ if rs_is_puiseux(p, x): return rs_puiseux(rs_cosh, p, x, prec) t = rs_exp(p, x, prec) t1 = rs_series_inversion(t, x, prec) return (t + t1)/2 def _tanh(p, x, prec): r""" Helper function of `rs\_tanh` Return the series expansion of tanh of a univariate series using Newton's method. It takes advantage of the fact that series expansion of atanh is easier than that of tanh. See Also ======== _tanh """ R = p.ring p1 = R(0) for precx in _giant_steps(prec): tmp = p - rs_atanh(p1, x, precx) tmp = rs_mul(tmp, 1 - rs_square(p1, x, prec), x, precx) p1 += tmp return p1 def rs_tanh(p, x, prec): """ Hyperbolic tangent of a series Return the series expansion of the tanh of ``p``, about 0. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_tanh >>> R, x, y = ring('x, y', QQ) >>> rs_tanh(x + xy, x, 4) -1/3x3y3 - x3y2 - x3y - 1/3x3 + xy + x See Also ======== tanh """ if rs_is_puiseux(p, x): return rs_puiseux(rs_tanh, p, x, prec) R = p.ring const = 0 if _has_constant_term(p, x): zm = R.zero_monom c = p[zm] if R.domain is EX: c_expr = c.as_expr() const = tanh(c_expr) elif isinstance(c, PolyElement): try: c_expr = c.as_expr() const = R(tanh(c_expr)) except ValueError: raise DomainError("The given series can't be expanded in " "this domain.") else: try: const = R(tanh(c)) except ValueError: raise DomainError("The given series can't be expanded in " "this domain.") p1 = p - c t1 = rs_tanh(p1, x, prec) t = rs_series_inversion(1 + constt1, x, prec) return rs_mul(const + t1, t, x, prec) if R.ngens == 1: return _tanh(p, x, prec) else: return rs_fun(p, _tanh, x, prec) def rs_newton(p, x, prec): """ Compute the truncated Newton sum of the polynomial ``p`` Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_newton >>> R, x = ring('x', QQ) >>> p = x2 - 2 >>> rs_newton(p, x, 5) 8x*4 + 4x*2 + 2 """ deg = p.degree() p1 = _invert_monoms(p) p2 = rs_series_inversion(p1, x, prec) p3 = rs_mul(p1.diff(x), p2, x, prec) res = deg - p3x return res def rs_hadamard_exp(p1, inverse=False): """ Return ``sum f_i/i!xi`` from ``sum f_ix*i``, where ``x`` is the first variable. If ``invers=True`` return ``sum f_ii!xi`` Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_hadamard_exp >>> R, x = ring('x', QQ) >>> p = 1 + x + x2 + x3 >>> rs_hadamard_exp(p) 1/6x*3 + 1/2x*2 + x + 1 """ R = p1.ring if R.domain != QQ: raise NotImplementedError p = R.zero if not inverse: for exp1, v1 in p1.items(): p[exp1] = v1/int(ifac(exp1[0])) else: for exp1, v1 in p1.items(): p[exp1] = v1int(ifac(exp1[0])) return p def rs_compose_add(p1, p2): """ compute the composed sum ``prod(p2(x - beta) for beta root of p1)`` Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_compose_add >>> R, x = ring('x', QQ) >>> f = x2 - 2 >>> g = x2 - 3 >>> rs_compose_add(f, g) x*4 - 10x*2 + 1 References ========== .. [1] A. Bostan, P. Flajolet, B. Salvy and E. Schost "Fast Computation with Two Algebraic Numbers", (2002) Research Report 4579, Institut National de Recherche en Informatique et en Automatique """ R = p1.ring x = R.gens[0] prec = p1.degree() p2.degree() + 1 np1 = rs_newton(p1, x, prec) np1e = rs_hadamard_exp(np1) np2 = rs_newton(p2, x, prec) np2e = rs_hadamard_exp(np2) np3e = rs_mul(np1e, np2e, x, prec) np3 = rs_hadamard_exp(np3e, True) np3a = (np3[(0,)] - np3)/x q = rs_integrate(np3a, x) q = rs_exp(q, x, prec) q = _invert_monoms(q) q = q.primitive()[1] dp = p1.degree() * p2.degree() - q.degree() # `dp` is the multiplicity of the zeroes of the resultant; # these zeroes are missed in this computation so they are put here. # if p1 and p2 are monic irreducible polynomials, # there are zeroes in the resultant # if and only if p1 = p2 ; in fact in that case p1 and p2 have a # root in common, so gcd(p1, p2) != 1; being p1 and p2 irreducible # this means p1 = p2 if dp: q = qxdp return q _convert_func = { 'sin': 'rs_sin', 'cos': 'rs_cos', 'exp': 'rs_exp', 'tan': 'rs_tan', 'log': 'rs_log' } def rs_min_pow(expr, series_rs, a): """Find the minimum power of `a` in the series expansion of expr""" series = 0 n = 2 while series == 0: series = _rs_series(expr, series_rs, a, n) n = 2 R = series.ring a = R(a) i = R.gens.index(a) return min(series, key=lambda t: t[i])[i] def _rs_series(expr, series_rs, a, prec): # TODO Use _parallel_dict_from_expr instead of sring as sring is # inefficient. For details, read the todo in sring. args = expr.args R = series_rs.ring # expr does not contain any function to be expanded if not any(arg.has(Function) for arg in args) and not expr.is_Function: return series_rs if not expr.has(a): return series_rs elif expr.is_Function: arg = args[0] if len(args) > 1: raise NotImplementedError R1, series = sring(arg, domain=QQ, expand=False, series=True) series_inner = _rs_series(arg, series, a, prec) # Why do we need to compose these three rings? # # We want to use a simple domain (like ``QQ`` or ``RR``) but they don't # support symbolic coefficients. We need a ring that for example lets # us have `sin(1)` and `cos(1)` as coefficients if we are expanding # `sin(x + 1)`. The ``EX`` domain allows all symbolic coefficients, but # that makes it very complex and hence slow. # # To solve this problem, we add only those symbolic elements as # generators to our ring, that we need. Here, series_inner might # involve terms like `sin(4)`, `exp(a)`, etc, which are not there in # R1 or R. Hence, we compose these three rings to create one that has # the generators of all three. R = R.compose(R1).compose(series_inner.ring) series_inner = series_inner.set_ring(R) series = eval(_convert_func[str(expr.func)])(series_inner, R(a), prec) return series elif expr.is_Mul: n = len(args) for arg in args: # XXX Looks redundant if not arg.is_Number: R1, _ = sring(arg, expand=False, series=True) R = R.compose(R1) min_pows = list(map(rs_min_pow, args, [R(arg) for arg in args], [a]len(args))) sum_pows = sum(min_pows) series = R(1) for i in range(n): _series = _rs_series(args[i], R(args[i]), a, prec - sum_pows + min_pows[i]) R = R.compose(_series.ring) _series = _series.set_ring(R) series = series.set_ring(R) series = _series series = rs_trunc(series, R(a), prec) return series elif expr.is_Add: n = len(args) series = R(0) for i in range(n): _series = _rs_series(args[i], R(args[i]), a, prec) R = R.compose(_series.ring) _series = _series.set_ring(R) series = series.set_ring(R) series += _series return series elif expr.is_Pow: R1, _ = sring(expr.base, domain=QQ, expand=False, series=True) R = R.compose(R1) series_inner = _rs_series(expr.base, R(expr.base), a, prec) return rs_pow(series_inner, expr.exp, series_inner.ring(a), prec) # The `is_constant` method is buggy hence we check it at the end. # See issue #9786 for details. elif isinstance(expr, Expr) and expr.is_constant(): return sring(expr, domain=QQ, expand=False, series=True)[1] else: raise NotImplementedError def rs_series(expr, a, prec): """Return the series expansion of an expression about 0. Parameters ========== expr : :class:`Expr` a : :class:`Symbol` with respect to which expr is to be expanded prec : order of the series expansion Currently supports multivariate Taylor series expansion. This is much faster that Sympy's series method as it uses sparse polynomial operations. It automatically creates the simplest ring required to represent the series expansion through repeated calls to sring. Examples ======== >>> from sympy.polys.ring_series import rs_series >>> from sympy.functions import sin, cos, exp, tan >>> from sympy.core import symbols >>> from sympy.polys.domains import QQ >>> a, b, c = symbols('a, b, c') >>> rs_series(sin(a) + exp(a), a, 5) 1/24a4 + 1/2a*2 + 2a + 1 >>> series = rs_series(tan(a + b)cos(a + c), a, 2) >>> series.as_expr() -asin(c)tan(b) + acos(c)tan(b)2 + acos(c) + cos(c)tan(b) >>> series = rs_series(exp(aQQ(1,3) + aQQ(2, 5)), a, 1) >>> series.as_expr() a(11/15) + a(4/5)/2 + a(2/5) + a(2/3)/2 + a(1/3) + 1 """ R, series = sring(expr, domain=QQ, expand=False, series=True) if a not in R.symbols: R = R.add_gens([a, ]) series = series.set_ring(R) series = _rs_series(expr, series, a, prec) R = series.ring gen = R(a) prec_got = series.degree(gen) + 1 if prec_got >= prec: return rs_trunc(series, gen, prec) else: # increase the requested number of terms to get the desired # number keep increasing (up to 9) until the received order # is different than the original order and then predict how # many additional terms are needed for more in range(1, 9): p1 = _rs_series(expr, series, a, prec=prec + more) gen = gen.set_ring(p1.ring) new_prec = p1.degree(gen) + 1 if new_prec != prec_got: prec_do = ceiling(prec + (prec - prec_got)more/(new_prec - prec_got)) p1 = _rs_series(expr, series, a, prec=prec_do) while p1.degree(gen) + 1 < prec: p1 = _rs_series(expr, series, a, prec=prec_do) gen = gen.set_ring(p1.ring) prec_do *= 2 break else: break else: raise ValueError('Could not calculate %s terms for %s' % (str(prec), expr)) return rs_trunc(p1, gen, prec)
25e18d77ab511aafe67c1c345be29b44d680a7321461afdc68626bbeda3283ea	"""OO layer for several polynomial representations. """ from __future__ import print_function, division from sympy import oo from sympy.core.sympify import CantSympify from sympy.polys.polyerrors import CoercionFailed, NotReversible, NotInvertible from sympy.polys.polyutils import PicklableWithSlots class GenericPoly(PicklableWithSlots): """Base class for low-level polynomial representations. """ def ground_to_ring(f): """Make the ground domain a ring. """ return f.set_domain(f.dom.get_ring()) def ground_to_field(f): """Make the ground domain a field. """ return f.set_domain(f.dom.get_field()) def ground_to_exact(f): """Make the ground domain exact. """ return f.set_domain(f.dom.get_exact()) @classmethod def _perify_factors(per, result, include): if include: coeff, factors = result else: coeff = result factors = [ (per(g), k) for g, k in factors ] if include: return coeff, factors else: return factors from sympy.polys.densebasic import ( dmp_validate, dup_normal, dmp_normal, dup_convert, dmp_convert, dmp_from_sympy, dup_strip, dup_degree, dmp_degree_in, dmp_degree_list, dmp_negative_p, dup_LC, dmp_ground_LC, dup_TC, dmp_ground_TC, dmp_ground_nth, dmp_one, dmp_ground, dmp_zero_p, dmp_one_p, dmp_ground_p, dup_from_dict, dmp_from_dict, dmp_to_dict, dmp_deflate, dmp_inject, dmp_eject, dmp_terms_gcd, dmp_list_terms, dmp_exclude, dmp_slice_in, dmp_permute, dmp_to_tuple,) from sympy.polys.densearith import ( dmp_add_ground, dmp_sub_ground, dmp_mul_ground, dmp_quo_ground, dmp_exquo_ground, dmp_abs, dup_neg, dmp_neg, dup_add, dmp_add, dup_sub, dmp_sub, dup_mul, dmp_mul, dmp_sqr, dup_pow, dmp_pow, dmp_pdiv, dmp_prem, dmp_pquo, dmp_pexquo, dmp_div, dup_rem, dmp_rem, dmp_quo, dmp_exquo, dmp_add_mul, dmp_sub_mul, dmp_max_norm, dmp_l1_norm) from sympy.polys.densetools import ( dmp_clear_denoms, dmp_integrate_in, dmp_diff_in, dmp_eval_in, dup_revert, dmp_ground_trunc, dmp_ground_content, dmp_ground_primitive, dmp_ground_monic, dmp_compose, dup_decompose, dup_shift, dup_transform, dmp_lift) from sympy.polys.euclidtools import ( dup_half_gcdex, dup_gcdex, dup_invert, dmp_subresultants, dmp_resultant, dmp_discriminant, dmp_inner_gcd, dmp_gcd, dmp_lcm, dmp_cancel) from sympy.polys.sqfreetools import ( dup_gff_list, dmp_norm, dmp_sqf_p, dmp_sqf_norm, dmp_sqf_part, dmp_sqf_list, dmp_sqf_list_include) from sympy.polys.factortools import ( dup_cyclotomic_p, dmp_irreducible_p, dmp_factor_list, dmp_factor_list_include) from sympy.polys.rootisolation import ( dup_isolate_real_roots_sqf, dup_isolate_real_roots, dup_isolate_all_roots_sqf, dup_isolate_all_roots, dup_refine_real_root, dup_count_real_roots, dup_count_complex_roots, dup_sturm) from sympy.polys.polyerrors import ( UnificationFailed, PolynomialError) def init_normal_DMP(rep, lev, dom): return DMP(dmp_normal(rep, lev, dom), dom, lev) class DMP(PicklableWithSlots, CantSympify): """Dense Multivariate Polynomials over `K`. """ __slots__ = ['rep', 'lev', 'dom', 'ring'] def __init__(self, rep, dom, lev=None, ring=None): if lev is not None: if type(rep) is dict: rep = dmp_from_dict(rep, lev, dom) elif type(rep) is not list: rep = dmp_ground(dom.convert(rep), lev) else: rep, lev = dmp_validate(rep) self.rep = rep self.lev = lev self.dom = dom self.ring = ring def __repr__(f): return "%s(%s, %s, %s)" % (f.__class__.__name__, f.rep, f.dom, f.ring) def __hash__(f): return hash((f.__class__.__name__, f.to_tuple(), f.lev, f.dom, f.ring)) def unify(f, g): """Unify representations of two multivariate polynomials. """ if not isinstance(g, DMP) or f.lev != g.lev: raise UnificationFailed("can't unify %s with %s" % (f, g)) if f.dom == g.dom and f.ring == g.ring: return f.lev, f.dom, f.per, f.rep, g.rep else: lev, dom = f.lev, f.dom.unify(g.dom) ring = f.ring if g.ring is not None: if ring is not None: ring = ring.unify(g.ring) else: ring = g.ring F = dmp_convert(f.rep, lev, f.dom, dom) G = dmp_convert(g.rep, lev, g.dom, dom) def per(rep, dom=dom, lev=lev, kill=False): if kill: if not lev: return rep else: lev -= 1 return DMP(rep, dom, lev, ring) return lev, dom, per, F, G def per(f, rep, dom=None, kill=False, ring=None): """Create a DMP out of the given representation. """ lev = f.lev if kill: if not lev: return rep else: lev -= 1 if dom is None: dom = f.dom if ring is None: ring = f.ring return DMP(rep, dom, lev, ring) @classmethod def zero(cls, lev, dom, ring=None): return DMP(0, dom, lev, ring) @classmethod def one(cls, lev, dom, ring=None): return DMP(1, dom, lev, ring) @classmethod def from_list(cls, rep, lev, dom): """Create an instance of ``cls`` given a list of native coefficients. """ return cls(dmp_convert(rep, lev, None, dom), dom, lev) @classmethod def from_sympy_list(cls, rep, lev, dom): """Create an instance of ``cls`` given a list of SymPy coefficients. """ return cls(dmp_from_sympy(rep, lev, dom), dom, lev) def to_dict(f, zero=False): """Convert ``f`` to a dict representation with native coefficients. """ return dmp_to_dict(f.rep, f.lev, f.dom, zero=zero) def to_sympy_dict(f, zero=False): """Convert ``f`` to a dict representation with SymPy coefficients. """ rep = dmp_to_dict(f.rep, f.lev, f.dom, zero=zero) for k, v in rep.items(): rep[k] = f.dom.to_sympy(v) return rep def to_list(f): """Convert ``f`` to a list representation with native coefficients. """ return f.rep def to_sympy_list(f): """Convert ``f`` to a list representation with SymPy coefficients. """ def sympify_nested_list(rep): out = [] for val in rep: if isinstance(val, list): out.append(sympify_nested_list(val)) else: out.append(f.dom.to_sympy(val)) return out return sympify_nested_list(f.rep) def to_tuple(f): """ Convert ``f`` to a tuple representation with native coefficients. This is needed for hashing. """ return dmp_to_tuple(f.rep, f.lev) @classmethod def from_dict(cls, rep, lev, dom): """Construct and instance of ``cls`` from a ``dict`` representation. """ return cls(dmp_from_dict(rep, lev, dom), dom, lev) @classmethod def from_monoms_coeffs(cls, monoms, coeffs, lev, dom, ring=None): return DMP(dict(list(zip(monoms, coeffs))), dom, lev, ring) def to_ring(f): """Make the ground domain a ring. """ return f.convert(f.dom.get_ring()) def to_field(f): """Make the ground domain a field. """ return f.convert(f.dom.get_field()) def to_exact(f): """Make the ground domain exact. """ return f.convert(f.dom.get_exact()) def convert(f, dom): """Convert the ground domain of ``f``. """ if f.dom == dom: return f else: return DMP(dmp_convert(f.rep, f.lev, f.dom, dom), dom, f.lev) def slice(f, m, n, j=0): """Take a continuous subsequence of terms of ``f``. """ return f.per(dmp_slice_in(f.rep, m, n, j, f.lev, f.dom)) def coeffs(f, order=None): """Returns all non-zero coefficients from ``f`` in lex order. """ return [ c for _, c in dmp_list_terms(f.rep, f.lev, f.dom, order=order) ] def monoms(f, order=None): """Returns all non-zero monomials from ``f`` in lex order. """ return [ m for m, _ in dmp_list_terms(f.rep, f.lev, f.dom, order=order) ] def terms(f, order=None): """Returns all non-zero terms from ``f`` in lex order. """ return dmp_list_terms(f.rep, f.lev, f.dom, order=order) def all_coeffs(f): """Returns all coefficients from ``f``. """ if not f.lev: if not f: return [f.dom.zero] else: return [ c for c in f.rep ] else: raise PolynomialError('multivariate polynomials not supported') def all_monoms(f): """Returns all monomials from ``f``. """ if not f.lev: n = dup_degree(f.rep) if n < 0: return [(0,)] else: return [ (n - i,) for i, c in enumerate(f.rep) ] else: raise PolynomialError('multivariate polynomials not supported') def all_terms(f): """Returns all terms from a ``f``. """ if not f.lev: n = dup_degree(f.rep) if n < 0: return [((0,), f.dom.zero)] else: return [ ((n - i,), c) for i, c in enumerate(f.rep) ] else: raise PolynomialError('multivariate polynomials not supported') def lift(f): """Convert algebraic coefficients to rationals. """ return f.per(dmp_lift(f.rep, f.lev, f.dom), dom=f.dom.dom) def deflate(f): """Reduce degree of `f` by mapping `x_i^m` to `y_i`. """ J, F = dmp_deflate(f.rep, f.lev, f.dom) return J, f.per(F) def inject(f, front=False): """Inject ground domain generators into ``f``. """ F, lev = dmp_inject(f.rep, f.lev, f.dom, front=front) return f.__class__(F, f.dom.dom, lev) def eject(f, dom, front=False): """Eject selected generators into the ground domain. """ F = dmp_eject(f.rep, f.lev, dom, front=front) return f.__class__(F, dom, f.lev - len(dom.symbols)) def exclude(f): r""" Remove useless generators from ``f``. Returns the removed generators and the new excluded ``f``. Examples ======== >>> from sympy.polys.polyclasses import DMP >>> from sympy.polys.domains import ZZ >>> DMP([[[ZZ(1)]], [[ZZ(1)], [ZZ(2)]]], ZZ).exclude() ([2], DMP([[1], [1, 2]], ZZ, None)) """ J, F, u = dmp_exclude(f.rep, f.lev, f.dom) return J, f.__class__(F, f.dom, u) def permute(f, P): r""" Returns a polynomial in `K[x_{P(1)}, ..., x_{P(n)}]`. Examples ======== >>> from sympy.polys.polyclasses import DMP >>> from sympy.polys.domains import ZZ >>> DMP([[[ZZ(2)], [ZZ(1), ZZ(0)]], [[]]], ZZ).permute([1, 0, 2]) DMP([[[2], []], [[1, 0], []]], ZZ, None) >>> DMP([[[ZZ(2)], [ZZ(1), ZZ(0)]], [[]]], ZZ).permute([1, 2, 0]) DMP([[[1], []], [[2, 0], []]], ZZ, None) """ return f.per(dmp_permute(f.rep, P, f.lev, f.dom)) def terms_gcd(f): """Remove GCD of terms from the polynomial ``f``. """ J, F = dmp_terms_gcd(f.rep, f.lev, f.dom) return J, f.per(F) def add_ground(f, c): """Add an element of the ground domain to ``f``. """ return f.per(dmp_add_ground(f.rep, f.dom.convert(c), f.lev, f.dom)) def sub_ground(f, c): """Subtract an element of the ground domain from ``f``. """ return f.per(dmp_sub_ground(f.rep, f.dom.convert(c), f.lev, f.dom)) def mul_ground(f, c): """Multiply ``f`` by a an element of the ground domain. """ return f.per(dmp_mul_ground(f.rep, f.dom.convert(c), f.lev, f.dom)) def quo_ground(f, c): """Quotient of ``f`` by a an element of the ground domain. """ return f.per(dmp_quo_ground(f.rep, f.dom.convert(c), f.lev, f.dom)) def exquo_ground(f, c): """Exact quotient of ``f`` by a an element of the ground domain. """ return f.per(dmp_exquo_ground(f.rep, f.dom.convert(c), f.lev, f.dom)) def abs(f): """Make all coefficients in ``f`` positive. """ return f.per(dmp_abs(f.rep, f.lev, f.dom)) def neg(f): """Negate all coefficients in ``f``. """ return f.per(dmp_neg(f.rep, f.lev, f.dom)) def add(f, g): """Add two multivariate polynomials ``f`` and ``g``. """ lev, dom, per, F, G = f.unify(g) return per(dmp_add(F, G, lev, dom)) def sub(f, g): """Subtract two multivariate polynomials ``f`` and ``g``. """ lev, dom, per, F, G = f.unify(g) return per(dmp_sub(F, G, lev, dom)) def mul(f, g): """Multiply two multivariate polynomials ``f`` and ``g``. """ lev, dom, per, F, G = f.unify(g) return per(dmp_mul(F, G, lev, dom)) def sqr(f): """Square a multivariate polynomial ``f``. """ return f.per(dmp_sqr(f.rep, f.lev, f.dom)) def pow(f, n): """Raise ``f`` to a non-negative power ``n``. """ if isinstance(n, int): return f.per(dmp_pow(f.rep, n, f.lev, f.dom)) else: raise TypeError("``int`` expected, got %s" % type(n)) def pdiv(f, g): """Polynomial pseudo-division of ``f`` and ``g``. """ lev, dom, per, F, G = f.unify(g) q, r = dmp_pdiv(F, G, lev, dom) return per(q), per(r) def prem(f, g): """Polynomial pseudo-remainder of ``f`` and ``g``. """ lev, dom, per, F, G = f.unify(g) return per(dmp_prem(F, G, lev, dom)) def pquo(f, g): """Polynomial pseudo-quotient of ``f`` and ``g``. """ lev, dom, per, F, G = f.unify(g) return per(dmp_pquo(F, G, lev, dom)) def pexquo(f, g): """Polynomial exact pseudo-quotient of ``f`` and ``g``. """ lev, dom, per, F, G = f.unify(g) return per(dmp_pexquo(F, G, lev, dom)) def div(f, g): """Polynomial division with remainder of ``f`` and ``g``. """ lev, dom, per, F, G = f.unify(g) q, r = dmp_div(F, G, lev, dom) return per(q), per(r) def rem(f, g): """Computes polynomial remainder of ``f`` and ``g``. """ lev, dom, per, F, G = f.unify(g) return per(dmp_rem(F, G, lev, dom)) def quo(f, g): """Computes polynomial quotient of ``f`` and ``g``. """ lev, dom, per, F, G = f.unify(g) return per(dmp_quo(F, G, lev, dom)) def exquo(f, g): """Computes polynomial exact quotient of ``f`` and ``g``. """ lev, dom, per, F, G = f.unify(g) res = per(dmp_exquo(F, G, lev, dom)) if f.ring and res not in f.ring: from sympy.polys.polyerrors import ExactQuotientFailed raise ExactQuotientFailed(f, g, f.ring) return res def degree(f, j=0): """Returns the leading degree of ``f`` in ``x_j``. """ if isinstance(j, int): return dmp_degree_in(f.rep, j, f.lev) else: raise TypeError("``int`` expected, got %s" % type(j)) def degree_list(f): """Returns a list of degrees of ``f``. """ return dmp_degree_list(f.rep, f.lev) def total_degree(f): """Returns the total degree of ``f``. """ return max(sum(m) for m in f.monoms()) def homogenize(f, s): """Return homogeneous polynomial of ``f``""" td = f.total_degree() result = {} new_symbol = (s == len(f.terms()[0][0])) for term in f.terms(): d = sum(term[0]) if d < td: i = td - d else: i = 0 if new_symbol: result[term[0] + (i,)] = term[1] else: l = list(term[0]) l[s] += i result[tuple(l)] = term[1] return DMP(result, f.dom, f.lev + int(new_symbol), f.ring) def homogeneous_order(f): """Returns the homogeneous order of ``f``. """ if f.is_zero: return -oo monoms = f.monoms() tdeg = sum(monoms[0]) for monom in monoms: _tdeg = sum(monom) if _tdeg != tdeg: return None return tdeg def LC(f): """Returns the leading coefficient of ``f``. """ return dmp_ground_LC(f.rep, f.lev, f.dom) def TC(f): """Returns the trailing coefficient of ``f``. """ return dmp_ground_TC(f.rep, f.lev, f.dom) def nth(f, N): """Returns the ``n``-th coefficient of ``f``. """ if all(isinstance(n, int) for n in N): return dmp_ground_nth(f.rep, N, f.lev, f.dom) else: raise TypeError("a sequence of integers expected") def max_norm(f): """Returns maximum norm of ``f``. """ return dmp_max_norm(f.rep, f.lev, f.dom) def l1_norm(f): """Returns l1 norm of ``f``. """ return dmp_l1_norm(f.rep, f.lev, f.dom) def clear_denoms(f): """Clear denominators, but keep the ground domain. """ coeff, F = dmp_clear_denoms(f.rep, f.lev, f.dom) return coeff, f.per(F) def integrate(f, m=1, j=0): """Computes the ``m``-th order indefinite integral of ``f`` in ``x_j``. """ if not isinstance(m, int): raise TypeError("``int`` expected, got %s" % type(m)) if not isinstance(j, int): raise TypeError("``int`` expected, got %s" % type(j)) return f.per(dmp_integrate_in(f.rep, m, j, f.lev, f.dom)) def diff(f, m=1, j=0): """Computes the ``m``-th order derivative of ``f`` in ``x_j``. """ if not isinstance(m, int): raise TypeError("``int`` expected, got %s" % type(m)) if not isinstance(j, int): raise TypeError("``int`` expected, got %s" % type(j)) return f.per(dmp_diff_in(f.rep, m, j, f.lev, f.dom)) def eval(f, a, j=0): """Evaluates ``f`` at the given point ``a`` in ``x_j``. """ if not isinstance(j, int): raise TypeError("``int`` expected, got %s" % type(j)) return f.per(dmp_eval_in(f.rep, f.dom.convert(a), j, f.lev, f.dom), kill=True) def half_gcdex(f, g): """Half extended Euclidean algorithm, if univariate. """ lev, dom, per, F, G = f.unify(g) if not lev: s, h = dup_half_gcdex(F, G, dom) return per(s), per(h) else: raise ValueError('univariate polynomial expected') def gcdex(f, g): """Extended Euclidean algorithm, if univariate. """ lev, dom, per, F, G = f.unify(g) if not lev: s, t, h = dup_gcdex(F, G, dom) return per(s), per(t), per(h) else: raise ValueError('univariate polynomial expected') def invert(f, g): """Invert ``f`` modulo ``g``, if possible. """ lev, dom, per, F, G = f.unify(g) if not lev: return per(dup_invert(F, G, dom)) else: raise ValueError('univariate polynomial expected') def revert(f, n): """Compute ``f(-1)`` mod ``xn``. """ if not f.lev: return f.per(dup_revert(f.rep, n, f.dom)) else: raise ValueError('univariate polynomial expected') def subresultants(f, g): """Computes subresultant PRS sequence of ``f`` and ``g``. """ lev, dom, per, F, G = f.unify(g) R = dmp_subresultants(F, G, lev, dom) return list(map(per, R)) def resultant(f, g, includePRS=False): """Computes resultant of ``f`` and ``g`` via PRS. """ lev, dom, per, F, G = f.unify(g) if includePRS: res, R = dmp_resultant(F, G, lev, dom, includePRS=includePRS) return per(res, kill=True), list(map(per, R)) return per(dmp_resultant(F, G, lev, dom), kill=True) def discriminant(f): """Computes discriminant of ``f``. """ return f.per(dmp_discriminant(f.rep, f.lev, f.dom), kill=True) def cofactors(f, g): """Returns GCD of ``f`` and ``g`` and their cofactors. """ lev, dom, per, F, G = f.unify(g) h, cff, cfg = dmp_inner_gcd(F, G, lev, dom) return per(h), per(cff), per(cfg) def gcd(f, g): """Returns polynomial GCD of ``f`` and ``g``. """ lev, dom, per, F, G = f.unify(g) return per(dmp_gcd(F, G, lev, dom)) def lcm(f, g): """Returns polynomial LCM of ``f`` and ``g``. """ lev, dom, per, F, G = f.unify(g) return per(dmp_lcm(F, G, lev, dom)) def cancel(f, g, include=True): """Cancel common factors in a rational function ``f/g``. """ lev, dom, per, F, G = f.unify(g) if include: F, G = dmp_cancel(F, G, lev, dom, include=True) else: cF, cG, F, G = dmp_cancel(F, G, lev, dom, include=False) F, G = per(F), per(G) if include: return F, G else: return cF, cG, F, G def trunc(f, p): """Reduce ``f`` modulo a constant ``p``. """ return f.per(dmp_ground_trunc(f.rep, f.dom.convert(p), f.lev, f.dom)) def monic(f): """Divides all coefficients by ``LC(f)``. """ return f.per(dmp_ground_monic(f.rep, f.lev, f.dom)) def content(f): """Returns GCD of polynomial coefficients. """ return dmp_ground_content(f.rep, f.lev, f.dom) def primitive(f): """Returns content and a primitive form of ``f``. """ cont, F = dmp_ground_primitive(f.rep, f.lev, f.dom) return cont, f.per(F) def compose(f, g): """Computes functional composition of ``f`` and ``g``. """ lev, dom, per, F, G = f.unify(g) return per(dmp_compose(F, G, lev, dom)) def decompose(f): """Computes functional decomposition of ``f``. """ if not f.lev: return list(map(f.per, dup_decompose(f.rep, f.dom))) else: raise ValueError('univariate polynomial expected') def shift(f, a): """Efficiently compute Taylor shift ``f(x + a)``. """ if not f.lev: return f.per(dup_shift(f.rep, f.dom.convert(a), f.dom)) else: raise ValueError('univariate polynomial expected') def transform(f, p, q): """Evaluate functional transformation ``qn f(p/q)``.""" if f.lev: raise ValueError('univariate polynomial expected') lev, dom, per, P, Q = p.unify(q) lev, dom, per, F, P = f.unify(per(P, dom, lev)) lev, dom, per, F, Q = per(F, dom, lev).unify(per(Q, dom, lev)) if not lev: return per(dup_transform(F, P, Q, dom)) else: raise ValueError('univariate polynomial expected') def sturm(f): """Computes the Sturm sequence of ``f``. """ if not f.lev: return list(map(f.per, dup_sturm(f.rep, f.dom))) else: raise ValueError('univariate polynomial expected') def gff_list(f): """Computes greatest factorial factorization of ``f``. """ if not f.lev: return [ (f.per(g), k) for g, k in dup_gff_list(f.rep, f.dom) ] else: raise ValueError('univariate polynomial expected') def norm(f): """Computes ``Norm(f)``.""" r = dmp_norm(f.rep, f.lev, f.dom) return f.per(r, dom=f.dom.dom) def sqf_norm(f): """Computes square-free norm of ``f``. """ s, g, r = dmp_sqf_norm(f.rep, f.lev, f.dom) return s, f.per(g), f.per(r, dom=f.dom.dom) def sqf_part(f): """Computes square-free part of ``f``. """ return f.per(dmp_sqf_part(f.rep, f.lev, f.dom)) def sqf_list(f, all=False): """Returns a list of square-free factors of ``f``. """ coeff, factors = dmp_sqf_list(f.rep, f.lev, f.dom, all) return coeff, [ (f.per(g), k) for g, k in factors ] def sqf_list_include(f, all=False): """Returns a list of square-free factors of ``f``. """ factors = dmp_sqf_list_include(f.rep, f.lev, f.dom, all) return [ (f.per(g), k) for g, k in factors ] def factor_list(f): """Returns a list of irreducible factors of ``f``. """ coeff, factors = dmp_factor_list(f.rep, f.lev, f.dom) return coeff, [ (f.per(g), k) for g, k in factors ] def factor_list_include(f): """Returns a list of irreducible factors of ``f``. """ factors = dmp_factor_list_include(f.rep, f.lev, f.dom) return [ (f.per(g), k) for g, k in factors ] def intervals(f, all=False, eps=None, inf=None, sup=None, fast=False, sqf=False): """Compute isolating intervals for roots of ``f``. """ if not f.lev: if not all: if not sqf: return dup_isolate_real_roots(f.rep, f.dom, eps=eps, inf=inf, sup=sup, fast=fast) else: return dup_isolate_real_roots_sqf(f.rep, f.dom, eps=eps, inf=inf, sup=sup, fast=fast) else: if not sqf: return dup_isolate_all_roots(f.rep, f.dom, eps=eps, inf=inf, sup=sup, fast=fast) else: return dup_isolate_all_roots_sqf(f.rep, f.dom, eps=eps, inf=inf, sup=sup, fast=fast) else: raise PolynomialError( "can't isolate roots of a multivariate polynomial") def refine_root(f, s, t, eps=None, steps=None, fast=False): """ Refine an isolating interval to the given precision. ``eps`` should be a rational number. """ if not f.lev: return dup_refine_real_root(f.rep, s, t, f.dom, eps=eps, steps=steps, fast=fast) else: raise PolynomialError( "can't refine a root of a multivariate polynomial") def count_real_roots(f, inf=None, sup=None): """Return the number of real roots of ``f`` in ``[inf, sup]``. """ return dup_count_real_roots(f.rep, f.dom, inf=inf, sup=sup) def count_complex_roots(f, inf=None, sup=None): """Return the number of complex roots of ``f`` in ``[inf, sup]``. """ return dup_count_complex_roots(f.rep, f.dom, inf=inf, sup=sup) @property def is_zero(f): """Returns ``True`` if ``f`` is a zero polynomial. """ return dmp_zero_p(f.rep, f.lev) @property def is_one(f): """Returns ``True`` if ``f`` is a unit polynomial. """ return dmp_one_p(f.rep, f.lev, f.dom) @property def is_ground(f): """Returns ``True`` if ``f`` is an element of the ground domain. """ return dmp_ground_p(f.rep, None, f.lev) @property def is_sqf(f): """Returns ``True`` if ``f`` is a square-free polynomial. """ return dmp_sqf_p(f.rep, f.lev, f.dom) @property def is_monic(f): """Returns ``True`` if the leading coefficient of ``f`` is one. """ return f.dom.is_one(dmp_ground_LC(f.rep, f.lev, f.dom)) @property def is_primitive(f): """Returns ``True`` if the GCD of the coefficients of ``f`` is one. """ return f.dom.is_one(dmp_ground_content(f.rep, f.lev, f.dom)) @property def is_linear(f): """Returns ``True`` if ``f`` is linear in all its variables. """ return all(sum(monom) <= 1 for monom in dmp_to_dict(f.rep, f.lev, f.dom).keys()) @property def is_quadratic(f): """Returns ``True`` if ``f`` is quadratic in all its variables. """ return all(sum(monom) <= 2 for monom in dmp_to_dict(f.rep, f.lev, f.dom).keys()) @property def is_monomial(f): """Returns ``True`` if ``f`` is zero or has only one term. """ return len(f.to_dict()) <= 1 @property def is_homogeneous(f): """Returns ``True`` if ``f`` is a homogeneous polynomial. """ return f.homogeneous_order() is not None @property def is_irreducible(f): """Returns ``True`` if ``f`` has no factors over its domain. """ return dmp_irreducible_p(f.rep, f.lev, f.dom) @property def is_cyclotomic(f): """Returns ``True`` if ``f`` is a cyclotomic polynomial. """ if not f.lev: return dup_cyclotomic_p(f.rep, f.dom) else: return False def __abs__(f): return f.abs() def __neg__(f): return f.neg() def __add__(f, g): if not isinstance(g, DMP): try: g = f.per(dmp_ground(f.dom.convert(g), f.lev)) except TypeError: return NotImplemented except (CoercionFailed, NotImplementedError): if f.ring is not None: try: g = f.ring.convert(g) except (CoercionFailed, NotImplementedError): return NotImplemented return f.add(g) def __radd__(f, g): return f.__add__(g) def __sub__(f, g): if not isinstance(g, DMP): try: g = f.per(dmp_ground(f.dom.convert(g), f.lev)) except TypeError: return NotImplemented except (CoercionFailed, NotImplementedError): if f.ring is not None: try: g = f.ring.convert(g) except (CoercionFailed, NotImplementedError): return NotImplemented return f.sub(g) def __rsub__(f, g): return (-f).__add__(g) def __mul__(f, g): if isinstance(g, DMP): return f.mul(g) else: try: return f.mul_ground(g) except TypeError: return NotImplemented except (CoercionFailed, NotImplementedError): if f.ring is not None: try: return f.mul(f.ring.convert(g)) except (CoercionFailed, NotImplementedError): pass return NotImplemented def __div__(f, g): if isinstance(g, DMP): return f.exquo(g) else: try: return f.mul_ground(g) except TypeError: return NotImplemented except (CoercionFailed, NotImplementedError): if f.ring is not None: try: return f.exquo(f.ring.convert(g)) except (CoercionFailed, NotImplementedError): pass return NotImplemented def __rdiv__(f, g): if isinstance(g, DMP): return g.exquo(f) elif f.ring is not None: try: return f.ring.convert(g).exquo(f) except (CoercionFailed, NotImplementedError): pass return NotImplemented __truediv__ = __div__ __rtruediv__ = __rdiv__ def __rmul__(f, g): return f.__mul__(g) def __pow__(f, n): return f.pow(n) def __divmod__(f, g): return f.div(g) def __mod__(f, g): return f.rem(g) def __floordiv__(f, g): if isinstance(g, DMP): return f.quo(g) else: try: return f.quo_ground(g) except TypeError: return NotImplemented def __eq__(f, g): try: _, _, _, F, G = f.unify(g) if f.lev == g.lev: return F == G except UnificationFailed: pass return False def __ne__(f, g): return not f == g def eq(f, g, strict=False): if not strict: return f == g else: return f._strict_eq(g) def ne(f, g, strict=False): return not f.eq(g, strict=strict) def _strict_eq(f, g): return isinstance(g, f.__class__) and f.lev == g.lev \ and f.dom == g.dom \ and f.rep == g.rep def __lt__(f, g): _, _, _, F, G = f.unify(g) return F < G def __le__(f, g): _, _, _, F, G = f.unify(g) return F <= G def __gt__(f, g): _, _, _, F, G = f.unify(g) return F > G def __ge__(f, g): _, _, _, F, G = f.unify(g) return F >= G def __nonzero__(f): return not dmp_zero_p(f.rep, f.lev) __bool__ = __nonzero__ def init_normal_DMF(num, den, lev, dom): return DMF(dmp_normal(num, lev, dom), dmp_normal(den, lev, dom), dom, lev) class DMF(PicklableWithSlots, CantSympify): """Dense Multivariate Fractions over `K`. """ __slots__ = ['num', 'den', 'lev', 'dom', 'ring'] def __init__(self, rep, dom, lev=None, ring=None): num, den, lev = self._parse(rep, dom, lev) num, den = dmp_cancel(num, den, lev, dom) self.num = num self.den = den self.lev = lev self.dom = dom self.ring = ring @classmethod def new(cls, rep, dom, lev=None, ring=None): num, den, lev = cls._parse(rep, dom, lev) obj = object.__new__(cls) obj.num = num obj.den = den obj.lev = lev obj.dom = dom obj.ring = ring return obj @classmethod def _parse(cls, rep, dom, lev=None): if type(rep) is tuple: num, den = rep if lev is not None: if type(num) is dict: num = dmp_from_dict(num, lev, dom) if type(den) is dict: den = dmp_from_dict(den, lev, dom) else: num, num_lev = dmp_validate(num) den, den_lev = dmp_validate(den) if num_lev == den_lev: lev = num_lev else: raise ValueError('inconsistent number of levels') if dmp_zero_p(den, lev): raise ZeroDivisionError('fraction denominator') if dmp_zero_p(num, lev): den = dmp_one(lev, dom) else: if dmp_negative_p(den, lev, dom): num = dmp_neg(num, lev, dom) den = dmp_neg(den, lev, dom) else: num = rep if lev is not None: if type(num) is dict: num = dmp_from_dict(num, lev, dom) elif type(num) is not list: num = dmp_ground(dom.convert(num), lev) else: num, lev = dmp_validate(num) den = dmp_one(lev, dom) return num, den, lev def __repr__(f): return "%s((%s, %s), %s, %s)" % (f.__class__.__name__, f.num, f.den, f.dom, f.ring) def __hash__(f): return hash((f.__class__.__name__, dmp_to_tuple(f.num, f.lev), dmp_to_tuple(f.den, f.lev), f.lev, f.dom, f.ring)) def poly_unify(f, g): """Unify a multivariate fraction and a polynomial. """ if not isinstance(g, DMP) or f.lev != g.lev: raise UnificationFailed("can't unify %s with %s" % (f, g)) if f.dom == g.dom and f.ring == g.ring: return (f.lev, f.dom, f.per, (f.num, f.den), g.rep) else: lev, dom = f.lev, f.dom.unify(g.dom) ring = f.ring if g.ring is not None: if ring is not None: ring = ring.unify(g.ring) else: ring = g.ring F = (dmp_convert(f.num, lev, f.dom, dom), dmp_convert(f.den, lev, f.dom, dom)) G = dmp_convert(g.rep, lev, g.dom, dom) def per(num, den, cancel=True, kill=False, lev=lev): if kill: if not lev: return num/den else: lev = lev - 1 if cancel: num, den = dmp_cancel(num, den, lev, dom) return f.__class__.new((num, den), dom, lev, ring=ring) return lev, dom, per, F, G def frac_unify(f, g): """Unify representations of two multivariate fractions. """ if not isinstance(g, DMF) or f.lev != g.lev: raise UnificationFailed("can't unify %s with %s" % (f, g)) if f.dom == g.dom and f.ring == g.ring: return (f.lev, f.dom, f.per, (f.num, f.den), (g.num, g.den)) else: lev, dom = f.lev, f.dom.unify(g.dom) ring = f.ring if g.ring is not None: if ring is not None: ring = ring.unify(g.ring) else: ring = g.ring F = (dmp_convert(f.num, lev, f.dom, dom), dmp_convert(f.den, lev, f.dom, dom)) G = (dmp_convert(g.num, lev, g.dom, dom), dmp_convert(g.den, lev, g.dom, dom)) def per(num, den, cancel=True, kill=False, lev=lev): if kill: if not lev: return num/den else: lev = lev - 1 if cancel: num, den = dmp_cancel(num, den, lev, dom) return f.__class__.new((num, den), dom, lev, ring=ring) return lev, dom, per, F, G def per(f, num, den, cancel=True, kill=False, ring=None): """Create a DMF out of the given representation. """ lev, dom = f.lev, f.dom if kill: if not lev: return num/den else: lev -= 1 if cancel: num, den = dmp_cancel(num, den, lev, dom) if ring is None: ring = f.ring return f.__class__.new((num, den), dom, lev, ring=ring) def half_per(f, rep, kill=False): """Create a DMP out of the given representation. """ lev = f.lev if kill: if not lev: return rep else: lev -= 1 return DMP(rep, f.dom, lev) @classmethod def zero(cls, lev, dom, ring=None): return cls.new(0, dom, lev, ring=ring) @classmethod def one(cls, lev, dom, ring=None): return cls.new(1, dom, lev, ring=ring) def numer(f): """Returns the numerator of ``f``. """ return f.half_per(f.num) def denom(f): """Returns the denominator of ``f``. """ return f.half_per(f.den) def cancel(f): """Remove common factors from ``f.num`` and ``f.den``. """ return f.per(f.num, f.den) def neg(f): """Negate all coefficients in ``f``. """ return f.per(dmp_neg(f.num, f.lev, f.dom), f.den, cancel=False) def add(f, g): """Add two multivariate fractions ``f`` and ``g``. """ if isinstance(g, DMP): lev, dom, per, (F_num, F_den), G = f.poly_unify(g) num, den = dmp_add_mul(F_num, F_den, G, lev, dom), F_den else: lev, dom, per, F, G = f.frac_unify(g) (F_num, F_den), (G_num, G_den) = F, G num = dmp_add(dmp_mul(F_num, G_den, lev, dom), dmp_mul(F_den, G_num, lev, dom), lev, dom) den = dmp_mul(F_den, G_den, lev, dom) return per(num, den) def sub(f, g): """Subtract two multivariate fractions ``f`` and ``g``. """ if isinstance(g, DMP): lev, dom, per, (F_num, F_den), G = f.poly_unify(g) num, den = dmp_sub_mul(F_num, F_den, G, lev, dom), F_den else: lev, dom, per, F, G = f.frac_unify(g) (F_num, F_den), (G_num, G_den) = F, G num = dmp_sub(dmp_mul(F_num, G_den, lev, dom), dmp_mul(F_den, G_num, lev, dom), lev, dom) den = dmp_mul(F_den, G_den, lev, dom) return per(num, den) def mul(f, g): """Multiply two multivariate fractions ``f`` and ``g``. """ if isinstance(g, DMP): lev, dom, per, (F_num, F_den), G = f.poly_unify(g) num, den = dmp_mul(F_num, G, lev, dom), F_den else: lev, dom, per, F, G = f.frac_unify(g) (F_num, F_den), (G_num, G_den) = F, G num = dmp_mul(F_num, G_num, lev, dom) den = dmp_mul(F_den, G_den, lev, dom) return per(num, den) def pow(f, n): """Raise ``f`` to a non-negative power ``n``. """ if isinstance(n, int): return f.per(dmp_pow(f.num, n, f.lev, f.dom), dmp_pow(f.den, n, f.lev, f.dom), cancel=False) else: raise TypeError("``int`` expected, got %s" % type(n)) def quo(f, g): """Computes quotient of fractions ``f`` and ``g``. """ if isinstance(g, DMP): lev, dom, per, (F_num, F_den), G = f.poly_unify(g) num, den = F_num, dmp_mul(F_den, G, lev, dom) else: lev, dom, per, F, G = f.frac_unify(g) (F_num, F_den), (G_num, G_den) = F, G num = dmp_mul(F_num, G_den, lev, dom) den = dmp_mul(F_den, G_num, lev, dom) res = per(num, den) if f.ring is not None and res not in f.ring: from sympy.polys.polyerrors import ExactQuotientFailed raise ExactQuotientFailed(f, g, f.ring) return res exquo = quo def invert(f, check=True): """Computes inverse of a fraction ``f``. """ if check and f.ring is not None and not f.ring.is_unit(f): raise NotReversible(f, f.ring) res = f.per(f.den, f.num, cancel=False) return res @property def is_zero(f): """Returns ``True`` if ``f`` is a zero fraction. """ return dmp_zero_p(f.num, f.lev) @property def is_one(f): """Returns ``True`` if ``f`` is a unit fraction. """ return dmp_one_p(f.num, f.lev, f.dom) and \ dmp_one_p(f.den, f.lev, f.dom) def __neg__(f): return f.neg() def __add__(f, g): if isinstance(g, (DMP, DMF)): return f.add(g) try: return f.add(f.half_per(g)) except TypeError: return NotImplemented except (CoercionFailed, NotImplementedError): if f.ring is not None: try: return f.add(f.ring.convert(g)) except (CoercionFailed, NotImplementedError): pass return NotImplemented def __radd__(f, g): return f.__add__(g) def __sub__(f, g): if isinstance(g, (DMP, DMF)): return f.sub(g) try: return f.sub(f.half_per(g)) except TypeError: return NotImplemented except (CoercionFailed, NotImplementedError): if f.ring is not None: try: return f.sub(f.ring.convert(g)) except (CoercionFailed, NotImplementedError): pass return NotImplemented def __rsub__(f, g): return (-f).__add__(g) def __mul__(f, g): if isinstance(g, (DMP, DMF)): return f.mul(g) try: return f.mul(f.half_per(g)) except TypeError: return NotImplemented except (CoercionFailed, NotImplementedError): if f.ring is not None: try: return f.mul(f.ring.convert(g)) except (CoercionFailed, NotImplementedError): pass return NotImplemented def __rmul__(f, g): return f.__mul__(g) def __pow__(f, n): return f.pow(n) def __div__(f, g): if isinstance(g, (DMP, DMF)): return f.quo(g) try: return f.quo(f.half_per(g)) except TypeError: return NotImplemented except (CoercionFailed, NotImplementedError): if f.ring is not None: try: return f.quo(f.ring.convert(g)) except (CoercionFailed, NotImplementedError): pass return NotImplemented def __rdiv__(self, g): r = self.invert(check=False)*g if self.ring and r not in self.ring: from sympy.polys.polyerrors import ExactQuotientFailed raise ExactQuotientFailed(g, self, self.ring) return r __truediv__ = __div__ __rtruediv__ = __rdiv__ def __eq__(f, g): try: if isinstance(g, DMP): _, _, _, (F_num, F_den), G = f.poly_unify(g) if f.lev == g.lev: return dmp_one_p(F_den, f.lev, f.dom) and F_num == G else: _, _, _, F, G = f.frac_unify(g) if f.lev == g.lev: return F == G except UnificationFailed: pass return False def __ne__(f, g): try: if isinstance(g, DMP): _, _, _, (F_num, F_den), G = f.poly_unify(g) if f.lev == g.lev: return not (dmp_one_p(F_den, f.lev, f.dom) and F_num == G) else: _, _, _, F, G = f.frac_unify(g) if f.lev == g.lev: return F != G except UnificationFailed: pass return True def __lt__(f, g): _, _, _, F, G = f.frac_unify(g) return F < G def __le__(f, g): _, _, _, F, G = f.frac_unify(g) return F <= G def __gt__(f, g): _, _, _, F, G = f.frac_unify(g) return F > G def __ge__(f, g): _, _, _, F, G = f.frac_unify(g) return F >= G def __nonzero__(f): return not dmp_zero_p(f.num, f.lev) __bool__ = __nonzero__ def init_normal_ANP(rep, mod, dom): return ANP(dup_normal(rep, dom), dup_normal(mod, dom), dom) class ANP(PicklableWithSlots, CantSympify): """Dense Algebraic Number Polynomials over a field. """ __slots__ = ['rep', 'mod', 'dom'] def __init__(self, rep, mod, dom): if type(rep) is dict: self.rep = dup_from_dict(rep, dom) else: if type(rep) is not list: rep = [dom.convert(rep)] self.rep = dup_strip(rep) if isinstance(mod, DMP): self.mod = mod.rep else: if type(mod) is dict: self.mod = dup_from_dict(mod, dom) else: self.mod = dup_strip(mod) self.dom = dom def __repr__(f): return "%s(%s, %s, %s)" % (f.__class__.__name__, f.rep, f.mod, f.dom) def __hash__(f): return hash((f.__class__.__name__, f.to_tuple(), dmp_to_tuple(f.mod, 0), f.dom)) def unify(f, g): """Unify representations of two algebraic numbers. """ if not isinstance(g, ANP) or f.mod != g.mod: raise UnificationFailed("can't unify %s with %s" % (f, g)) if f.dom == g.dom: return f.dom, f.per, f.rep, g.rep, f.mod else: dom = f.dom.unify(g.dom) F = dup_convert(f.rep, f.dom, dom) G = dup_convert(g.rep, g.dom, dom) if dom != f.dom and dom != g.dom: mod = dup_convert(f.mod, f.dom, dom) else: if dom == f.dom: mod = f.mod else: mod = g.mod per = lambda rep: ANP(rep, mod, dom) return dom, per, F, G, mod def per(f, rep, mod=None, dom=None): return ANP(rep, mod or f.mod, dom or f.dom) @classmethod def zero(cls, mod, dom): return ANP(0, mod, dom) @classmethod def one(cls, mod, dom): return ANP(1, mod, dom) def to_dict(f): """Convert ``f`` to a dict representation with native coefficients. """ return dmp_to_dict(f.rep, 0, f.dom) def to_sympy_dict(f): """Convert ``f`` to a dict representation with SymPy coefficients. """ rep = dmp_to_dict(f.rep, 0, f.dom) for k, v in rep.items(): rep[k] = f.dom.to_sympy(v) return rep def to_list(f): """Convert ``f`` to a list representation with native coefficients. """ return f.rep def to_sympy_list(f): """Convert ``f`` to a list representation with SymPy coefficients. """ return [ f.dom.to_sympy(c) for c in f.rep ] def to_tuple(f): """ Convert ``f`` to a tuple representation with native coefficients. This is needed for hashing. """ return dmp_to_tuple(f.rep, 0) @classmethod def from_list(cls, rep, mod, dom): return ANP(dup_strip(list(map(dom.convert, rep))), mod, dom) def neg(f): return f.per(dup_neg(f.rep, f.dom)) def add(f, g): dom, per, F, G, mod = f.unify(g) return per(dup_add(F, G, dom)) def sub(f, g): dom, per, F, G, mod = f.unify(g) return per(dup_sub(F, G, dom)) def mul(f, g): dom, per, F, G, mod = f.unify(g) return per(dup_rem(dup_mul(F, G, dom), mod, dom)) def pow(f, n): """Raise ``f`` to a non-negative power ``n``. """ if isinstance(n, int): if n < 0: F, n = dup_invert(f.rep, f.mod, f.dom), -n else: F = f.rep return f.per(dup_rem(dup_pow(F, n, f.dom), f.mod, f.dom)) else: raise TypeError("``int`` expected, got %s" % type(n)) def div(f, g): dom, per, F, G, mod = f.unify(g) return (per(dup_rem(dup_mul(F, dup_invert(G, mod, dom), dom), mod, dom)), f.zero(mod, dom)) def rem(f, g): dom, _, _, G, mod = f.unify(g) s, h = dup_half_gcdex(G, mod, dom) if h == [dom.one]: return f.zero(mod, dom) else: raise NotInvertible("zero divisor") def quo(f, g): dom, per, F, G, mod = f.unify(g) return per(dup_rem(dup_mul(F, dup_invert(G, mod, dom), dom), mod, dom)) exquo = quo def LC(f): """Returns the leading coefficient of ``f``. """ return dup_LC(f.rep, f.dom) def TC(f): """Returns the trailing coefficient of ``f``. """ return dup_TC(f.rep, f.dom) @property def is_zero(f): """Returns ``True`` if ``f`` is a zero algebraic number. """ return not f @property def is_one(f): """Returns ``True`` if ``f`` is a unit algebraic number. """ return f.rep == [f.dom.one] @property def is_ground(f): """Returns ``True`` if ``f`` is an element of the ground domain. """ return not f.rep or len(f.rep) == 1 def __neg__(f): return f.neg() def __add__(f, g): if isinstance(g, ANP): return f.add(g) else: try: return f.add(f.per(g)) except (CoercionFailed, TypeError): return NotImplemented def __radd__(f, g): return f.__add__(g) def __sub__(f, g): if isinstance(g, ANP): return f.sub(g) else: try: return f.sub(f.per(g)) except (CoercionFailed, TypeError): return NotImplemented def __rsub__(f, g): return (-f).__add__(g) def __mul__(f, g): if isinstance(g, ANP): return f.mul(g) else: try: return f.mul(f.per(g)) except (CoercionFailed, TypeError): return NotImplemented def __rmul__(f, g): return f.__mul__(g) def __pow__(f, n): return f.pow(n) def __divmod__(f, g): return f.div(g) def __mod__(f, g): return f.rem(g) def __div__(f, g): if isinstance(g, ANP): return f.quo(g) else: try: return f.quo(f.per(g)) except (CoercionFailed, TypeError): return NotImplemented __truediv__ = __div__ def __eq__(f, g): try: _, _, F, G, _ = f.unify(g) return F == G except UnificationFailed: return False def __ne__(f, g): try: _, _, F, G, _ = f.unify(g) return F != G except UnificationFailed: return True def __lt__(f, g): _, _, F, G, _ = f.unify(g) return F < G def __le__(f, g): _, _, F, G, _ = f.unify(g) return F <= G def __gt__(f, g): _, _, F, G, _ = f.unify(g) return F > G def __ge__(f, g): _, _, F, G, _ = f.unify(g) return F >= G def __nonzero__(f): return bool(f.rep) __bool__ = __nonzero__
6669c5fe53c8bf26f61a102b93dc8a0c96033933c5bdd53b4d46196fe0a2e28a	""" Solving solvable quintics - An implementation of DS Dummit's paper Paper : http://www.ams.org/journals/mcom/1991-57-195/S0025-5718-1991-1079014-X/S0025-5718-1991-1079014-X.pdf Mathematica notebook: http://www.emba.uvm.edu/~ddummit/quintics/quintics.nb """ from __future__ import print_function, division from sympy.core import S, Symbol from sympy.core.evalf import N from sympy.core.numbers import I from sympy.functions import sqrt from sympy.polys.polytools import Poly from sympy.utilities import public x = Symbol('x') @public class PolyQuintic(object): """Special functions for solvable quintics""" def __init__(self, poly): _, _, self.p, self.q, self.r, self.s = poly.all_coeffs() self.zeta1 = S(-1)/4 + (sqrt(5)/4) + Isqrt((sqrt(5)/8) + S(5)/8) self.zeta2 = (-sqrt(5)/4) - S(1)/4 + Isqrt((-sqrt(5)/8) + S(5)/8) self.zeta3 = (-sqrt(5)/4) - S(1)/4 - Isqrt((-sqrt(5)/8) + S(5)/8) self.zeta4 = S(-1)/4 + (sqrt(5)/4) - Isqrt((sqrt(5)/8) + S(5)/8) @property def f20(self): p, q, r, s = self.p, self.q, self.r, self.s f20 = q*8 - 13pq6r + p*5q*2r*2 + 65p*2q*4r*2 - 4p*6r*3 - 128p*3q*2r*3 + 17q*4r*3 + 48p*4r*4 - 16pq2r*4 - 192p*2r*5 + 256r*6 - 4p*5q*3s - 12p2q*5s + 18p6qrs + 12p3q*3rs - 124q*5rs + 196p*4qr2s + 590pq*3r*2s - 160p2qr3s - 1600qr*4s - 27p7s*2 - 150p*4q*2s*2 - 125pq4s*2 - 99p*5rs2 - 725p*2q*2rs2 + 1200p*3r*2s*2 + 3250q*2r*2s*2 - 2000pr3s*2 - 1250pqrs3 + 3125p*2s*4 - 9375rs4-(2pq6 - 19p*2q*4r + 51p3q*2r*2 - 3q*4r*2 - 32p*4r*3 - 76pq2r*3 + 256p*2r*4 - 512r*5 + 31p*3q*3s + 58q5s - 117p4qrs - 105pq*3rs - 260p*2qr2s + 2400qr*3s + 108p5s*2 + 325p*2q*2s*2 - 525p*3rs2 - 2750q*2rs2 + 500pr2s*2 - 625pqs*3 + 3125s*4)x+(p*2q*4 - 6p*3q*2r - 8q4r + 9p4r*2 + 76pq2r*2 - 136p*2r*3 + 400r*4 - 50pq3s + 90p2qrs - 1400qr*2s + 625q2s*2 + 500prs*2)x*2-(2q*4 - 21pq2r + 40p2r*2 - 160r*3 + 15p*2qs + 400qrs - 125ps*2)x*3+(2pq2 - 6p*2r + 40r2 - 50qs)x*4 + 8rx5 + x6 return Poly(f20, x) @property def b(self): p, q, r, s = self.p, self.q, self.r, self.s b = ( [], [0,0,0,0,0,0], [0,0,0,0,0,0], [0,0,0,0,0,0], [0,0,0,0,0,0],) b[1][5] = 100p*7q*7 + 2175p*4q*9 + 10500pq11 - 1100p*8q*5r - 27975p5q*7r - 152950p2q*9r + 4125p9q*3r*2 + 128875p*6q*5r*2 + 830525p*3q*7r*2 - 59450q*9r*2 - 5400p*10qr3 - 243800p*7q*3r*3 - 2082650p*4q*5r*3 + 333925pq7r*3 + 139200p*8qr4 + 2406000p*5q*3r*4 + 122600p*2q*5r*4 - 1254400p*6qr5 - 3776000p*3q*3r*5 - 1832000q*5r*5 + 4736000p*4qr6 + 6720000pq3r*6 - 6400000p*2qr7 + 900p*9q*4s + 37400p6q*6s + 281625p3q*8s + 435000q10s - 6750p10q*2rs - 322300p*7q*4rs - 2718575p*4q*6rs - 4214250pq8rs + 16200p*11r*2s + 859275p8q*2r*2s + 8925475p5q*4r*2s + 14427875p2q*6r*2s - 453600p9r*3s - 10038400p6q*2r*3s - 17397500p3q*4r*3s + 11333125q6r*3s + 4451200p7r*4s + 15850000p4q*2r*4s - 34000000pq*4r*4s - 17984000p5r*5s + 10000000p2q*2r*5s + 25600000p3r*6s + 8000000q2r*6s - 6075p11qs2 + 83250p*8q*3s*2 + 1282500p*5q*5s*2 + 2862500p*2q*7s*2 - 724275p*9qrs*2 - 9807250p*6q*3rs2 - 28374375p*3q*5rs2 - 22212500q*7rs2 + 8982000p*7qr2s*2 + 39600000p*4q*3r*2s*2 + 61746875pq5r*2s*2 + 1010000p*5qr3s*2 + 1000000p*2q*3r*3s*2 - 78000000p*3qr4s*2 - 30000000q*3r*4s*2 - 80000000pqr*5s*2 + 759375p*10s*3 + 9787500p*7q*2s*3 + 39062500p*4q*4s*3 + 52343750pq6s*3 - 12301875p*8rs3 - 98175000p*5q*2rs3 - 225078125p*2q*4rs3 + 54900000p*6r*2s*3 + 310000000p*3q*2r*2s*3 + 7890625q*4r*2s*3 - 51250000p*4r*3s*3 + 420000000pq2r*3s*3 - 110000000p*2r*4s*3 + 200000000r*5s*3 - 2109375p*6qs4 + 21093750p*3q*3s*4 + 89843750q*5s*4 - 182343750p*4qrs*4 - 733203125pq3rs4 + 196875000p*2qr2s*4 - 1125000000qr3s*4 + 158203125p*5s*5 + 566406250p*2q*2s*5 - 101562500p*3rs5 + 1669921875q*2rs5 - 1250000000pr2s*5 + 1220703125pqs*6 - 6103515625s*7 b[1][4] = -1000p*5q*7 - 7250p*2q*9 + 10800p*6q*5r + 96900p3q*7r + 52500q9r - 37400p7q*3r*2 - 470850p*4q*5r*2 - 640600pq7r*2 + 39600p*8qr3 + 983600p*5q*3r*3 + 2848100p*2q*5r*3 - 814400p*6qr4 - 6076000p*3q*3r*4 - 2308000q*5r*4 + 5024000p*4qr5 + 9680000pq3r*5 - 9600000p*2qr6 - 13800p*7q*4s - 94650p4q*6s + 26500pq*8s + 86400p8q*2rs + 816500p*5q*4rs + 257500p*2q*6rs - 91800p*9r*2s - 1853700p6q*2r*2s - 630000p3q*4r*2s + 8971250q6r*2s + 2071200p7r*3s + 7240000p4q*2r*3s - 29375000pq*4r*3s - 14416000p5r*4s + 5200000p2q*2r*4s + 30400000p3r*5s + 12000000q2r*5s - 64800p9qs2 - 567000p*6q*3s*2 - 1655000p*3q*5s*2 - 6987500q*7s*2 - 337500p*7qrs*2 - 8462500p*4q*3rs2 + 5812500pq5rs2 + 24930000p*5qr2s*2 + 69125000p*2q*3r*2s*2 - 103500000p*3qr3s*2 - 30000000q*3r*3s*2 - 90000000pqr*4s*2 + 708750p*8s*3 + 5400000p*5q*2s*3 - 8906250p*2q*4s*3 - 18562500p*6rs3 + 625000p*3q*2rs3 - 29687500q*4rs3 + 75000000p*4r*2s*3 + 416250000pq2r*2s*3 - 60000000p*2r*3s*3 + 300000000r*4s*3 - 71718750p*4qs4 - 189062500pq3s*4 - 210937500p*2qrs*4 - 1187500000qr2s*4 + 187500000p*3s*5 + 800781250q*2s*5 + 390625000prs*5 b[1][3] = 500p*6q*5 + 6350p*3q*7 + 19800q*9 - 3750p*7q*3r - 65100p4q*5r - 264950pq*7r + 6750p8qr2 + 209050p*5q*3r*2 + 1217250p*2q*5r*2 - 219000p*6qr3 - 2510000p*3q*3r*3 - 1098500q*5r*3 + 2068000p*4qr4 + 5060000pq3r*4 - 5200000p*2qr5 + 6750p*8q*2s + 96350p5q*4s + 346000p2q*6s - 20250p9rs - 459900p*6q*2rs - 1828750p*3q*4rs + 2930000q*6rs + 594000p*7r*2s + 4301250p4q*2r*2s - 10906250pq*4r*2s - 5252000p5r*3s + 1450000p2q*2r*3s + 12800000p3r*4s + 6500000q2r*4s - 74250p7qs2 - 1418750p*4q*3s*2 - 5956250pq5s*2 + 4297500p*5qrs*2 + 29906250p*2q*3rs2 - 31500000p*3qr2s*2 - 12500000q*3r*2s*2 - 35000000pqr*3s*2 - 1350000p*6s*3 - 6093750p*3q*2s*3 - 17500000q*4s*3 + 7031250p*4rs3 + 127812500pq2rs3 - 18750000p*2r*2s*3 + 162500000r*3s*3 - 107812500p*2qs4 - 460937500qrs*4 + 214843750ps5 b[1][2] = -1950p*4q*5 - 14100pq7 + 14350p*5q*3r + 125600p2q*5r - 27900p6qr2 - 402250p*3q*3r*2 - 288250q*5r*2 + 436000p*4qr3 + 1345000pq3r*3 - 1400000p*2qr4 - 9450p*6q*2s + 1250p3q*4s + 465000q6s + 49950p7rs + 302500p*4q*2rs - 1718750pq4rs - 834000p*5r*2s - 437500p2q*2r*2s + 3100000p3r*3s + 1750000q2r*3s + 292500p5qs2 + 1937500p*2q*3s*2 - 3343750p*3qrs*2 - 1875000q*3rs2 - 8125000pqr*2s*2 + 1406250p*4s*3 + 12343750pq2s*3 - 5312500p*2rs3 + 43750000r*2s*3 - 74218750qs4 b[1][1] = 300p*5q*3 + 2150p*2q*5 - 1350p*6qr - 21500p*3q*3r - 61500q5r + 42000p4qr2 + 290000pq3r*2 - 300000p*2qr3 + 4050p*7s + 45000p4q*2s + 125000pq*4s - 108000p5rs - 643750p*2q*2rs + 700000p*3r*2s + 375000q2r*2s + 93750p3qs2 + 312500q*3s*2 - 1875000pqrs2 + 1406250p*2s*3 + 9375000rs3 b[1][0] = -1250p*3q*3 - 9000q*5 + 4500p*4qr + 46250pq3r - 50000p2qr2 - 6750p*5s - 43750p2q*2s + 75000p3rs + 62500q*2rs - 156250pqs*2 + 1562500s*3 b[2][5] = 200p*6q*11 - 250p*3q*13 - 10800q*15 - 3900p*7q*9r - 3325p4q*11r + 181800pq*13r + 26950p8q*7r*2 + 69625p*5q*9r*2 - 1214450p*2q*11r*2 - 78725p*9q*5r*3 - 368675p*6q*7r*3 + 4166325p*3q*9r*3 + 1131100q*11r*3 + 73400p*10q*3r*4 + 661950p*7q*5r*4 - 9151950p*4q*7r*4 - 16633075pq9r*4 + 36000p*11qr5 + 135600p*8q*3r*5 + 17321400p*5q*5r*5 + 85338300p*2q*7r*5 - 832000p*9qr6 - 21379200p*6q*3r*6 - 176044000p*3q*5r*6 - 1410000q*7r*6 + 6528000p*7qr7 + 129664000p*4q*3r*7 + 47344000pq5r*7 - 21504000p*5qr8 - 115200000p*2q*3r*8 + 25600000p*3qr9 + 64000000q*3r*9 + 15700p*8q*8s + 120525p5q*10s + 113250p2q*12s - 196900p9q*6rs - 1776925p*6q*8rs - 3062475p*3q*10rs - 4153500q*12rs + 857925p*10q*4r*2s + 10562775p7q*6r*2s + 34866250p4q*8r*2s + 73486750pq*10r*2s - 1333800p11q*2r*3s - 29212625p8q*4r*3s - 168729675p5q*6r*3s - 427230750p2q*8r*3s + 108000p12r*4s + 30384200p9q*2r*4s + 324535100p6q*4r*4s + 952666750p3q*6r*4s - 38076875q8r*4s - 4296000p10r*5s - 213606400p7q*2r*5s - 842060000p4q*4r*5s - 95285000pq*6r*5s + 61184000p8r*6s + 567520000p5q*2r*6s + 547000000p2q*4r*6s - 390912000p6r*7s - 812800000p3q*2r*7s - 924000000q4r*7s + 1152000000p4r*8s + 800000000pq*2r*8s - 1280000000p2r*9s + 141750p10q*5s*2 - 31500p*7q*7s*2 - 11325000p*4q*9s*2 - 31687500pq11s*2 - 1293975p*11q*3rs2 - 4803800p*8q*5rs2 + 71398250p*5q*7rs2 + 227625000p*2q*9rs2 + 3256200p*12qr2s*2 + 43870125p*9q*3r*2s*2 + 64581500p*6q*5r*2s*2 + 56090625p*3q*7r*2s*2 + 260218750q*9r*2s*2 - 74610000p*10qr3s*2 - 662186500p*7q*3r*3s*2 - 1987747500p*4q*5r*3s*2 - 811928125pq7r*3s*2 + 471286000p*8qr4s*2 + 2106040000p*5q*3r*4s*2 + 792687500p*2q*5r*4s*2 - 135120000p*6qr5s*2 + 2479000000p*3q*3r*5s*2 + 5242250000q*5r*5s*2 - 6400000000p*4qr6s*2 - 8620000000pq3r*6s*2 + 13280000000p*2qr7s*2 + 1600000000qr8s*2 + 273375p*12q*2s*3 - 13612500p*9q*4s*3 - 177250000p*6q*6s*3 - 511015625p*3q*8s*3 - 320937500q*10s*3 - 2770200p*13rs3 + 12595500p*10q*2rs3 + 543950000p*7q*4rs3 + 1612281250p*4q*6rs3 + 968125000pq8rs3 + 77031000p*11r*2s*3 + 373218750p*8q*2r*2s*3 + 1839765625p*5q*4r*2s*3 + 1818515625p*2q*6r*2s*3 - 776745000p*9r*3s*3 - 6861075000p*6q*2r*3s*3 - 20014531250p*3q*4r*3s*3 - 13747812500q*6r*3s*3 + 3768000000p*7r*4s*3 + 35365000000p*4q*2r*4s*3 + 34441875000pq4r*4s*3 - 9628000000p*5r*5s*3 - 63230000000p*2q*2r*5s*3 + 13600000000p*3r*6s*3 - 15000000000q*2r*6s*3 - 10400000000pr7s*3 - 45562500p*11qs4 - 525937500p*8q*3s*4 - 1364218750p*5q*5s*4 - 1382812500p*2q*7s*4 + 572062500p*9qrs*4 + 2473515625p*6q*3rs4 + 13192187500p*3q*5rs4 + 12703125000q*7rs4 - 451406250p*7qr2s*4 - 18153906250p*4q*3r*2s*4 - 36908203125pq5r*2s*4 - 9069375000p*5qr3s*4 + 79957812500p*2q*3r*3s*4 + 5512500000p*3qr4s*4 + 50656250000q*3r*4s*4 + 74750000000pqr*5s*4 + 56953125p*10s*5 + 1381640625p*7q*2s*5 - 781250000p*4q*4s*5 + 878906250pq6s*5 - 2655703125p*8rs5 - 3223046875p*5q*2rs5 - 35117187500p*2q*4rs5 + 26573437500p*6r*2s*5 + 14785156250p*3q*2r*2s*5 - 52050781250q*4r*2s*5 - 103062500000p*4r*3s*5 - 281796875000pq2r*3s*5 + 146875000000p*2r*4s*5 - 37500000000r*5s*5 - 8789062500p*6qs6 - 3906250000p*3q*3s*6 + 1464843750q*5s*6 + 102929687500p*4qrs*6 + 297119140625pq3rs6 - 217773437500p*2qr2s*6 + 167968750000qr3s*6 + 10986328125p*5s*7 + 98876953125p*2q*2s*7 - 188964843750p*3rs7 - 278320312500q*2rs7 + 517578125000pr2s*7 - 610351562500pqs*8 + 762939453125s*9 b[2][4] = -200p*7q*9 + 1850p*4q*11 + 21600pq13 + 3200p*8q*7r - 19200p5q*9r - 316350p2q*11r - 19050p9q*5r*2 + 37400p*6q*7r*2 + 1759250p*3q*9r*2 + 440100q*11r*2 + 48750p*10q*3r*3 + 190200p*7q*5r*3 - 4604200p*4q*7r*3 - 6072800pq9r*3 - 43200p*11qr4 - 834500p*8q*3r*4 + 4916000p*5q*5r*4 + 27926850p*2q*7r*4 + 969600p*9qr5 + 2467200p*6q*3r*5 - 45393200p*3q*5r*5 - 5399500q*7r*5 - 7283200p*7qr6 + 10536000p*4q*3r*6 + 41656000pq5r*6 + 22784000p*5qr7 - 35200000p*2q*3r*7 - 25600000p*3qr8 + 96000000q*3r*8 - 3000p*9q*6s + 40400p6q*8s + 136550p3q*10s - 1647000q12s + 40500p10q*4rs - 173600p*7q*6rs - 126500p*4q*8rs + 23969250pq10rs - 153900p*11q*2r*2s - 486150p8q*4r*2s - 4115800p5q*6r*2s - 112653250p2q*8r*2s + 129600p12r*3s + 2683350p9q*2r*3s + 10906650p6q*4r*3s + 187289500p3q*6r*3s + 44098750q8r*3s - 4384800p10r*4s - 35660800p7q*2r*4s - 175420000p4q*4r*4s - 426538750pq*6r*4s + 60857600p8r*5s + 349436000p5q*2r*5s + 900600000p2q*4r*5s - 429568000p6r*6s - 1511200000p3q*2r*6s - 1286000000q4r*6s + 1472000000p4r*7s + 1440000000pq*2r*7s - 1920000000p2r*8s - 36450p11q*3s*2 - 188100p*8q*5s*2 - 5504750p*5q*7s*2 - 37968750p*2q*9s*2 + 255150p*12qrs*2 + 2754000p*9q*3rs2 + 49196500p*6q*5rs2 + 323587500p*3q*7rs2 - 83250000q*9rs2 - 465750p*10qr2s*2 - 31881500p*7q*3r*2s*2 - 415585000p*4q*5r*2s*2 + 1054775000pq7r*2s*2 - 96823500p*8qr3s*2 - 701490000p*5q*3r*3s*2 - 2953531250p*2q*5r*3s*2 + 1454560000p*6qr4s*2 + 7670500000p*3q*3r*4s*2 + 5661062500q*5r*4s*2 - 7785000000p*4qr5s*2 - 9450000000pq3r*5s*2 + 14000000000p*2qr6s*2 + 2400000000qr7s*2 - 437400p*13s*3 - 10145250p*10q*2s*3 - 121912500p*7q*4s*3 - 576531250p*4q*6s*3 - 528593750pq8s*3 + 12939750p*11rs3 + 313368750p*8q*2rs3 + 2171812500p*5q*4rs3 + 2381718750p*2q*6rs3 - 124638750p*9r*2s*3 - 3001575000p*6q*2r*2s*3 - 12259375000p*3q*4r*2s*3 - 9985312500q*6r*2s*3 + 384000000p*7r*3s*3 + 13997500000p*4q*2r*3s*3 + 20749531250pq4r*3s*3 - 553500000p*5r*4s*3 - 41835000000p*2q*2r*4s*3 + 5420000000p*3r*5s*3 - 16300000000q*2r*5s*3 - 17600000000pr6s*3 - 7593750p*9qs4 + 289218750p*6q*3s*4 + 3591406250p*3q*5s*4 + 5992187500q*7s*4 + 658125000p*7qrs*4 - 269531250p*4q*3rs4 - 15882812500pq5rs4 - 4785000000p*5qr2s*4 + 54375781250p*2q*3r*2s*4 - 5668750000p*3qr3s*4 + 35867187500q*3r*3s*4 + 113875000000pqr*4s*4 - 544218750p*8s*5 - 5407031250p*5q*2s*5 - 14277343750p*2q*4s*5 + 5421093750p*6rs5 - 24941406250p*3q*2rs5 - 25488281250q*4rs5 - 11500000000p*4r*2s*5 - 231894531250pq2r*2s*5 - 6250000000p*2r*3s*5 - 43750000000r*4s*5 + 35449218750p*4qs6 + 137695312500pq3s*6 + 34667968750p*2qrs*6 + 202148437500qr2s*6 - 33691406250p*3s*7 - 214843750000q*2s*7 - 31738281250prs*7 b[2][3] = -800p*5q*9 - 5400p*2q*11 + 5800p*6q*7r + 48750p3q*9r + 16200q11r - 3000p7q*5r*2 - 108350p*4q*7r*2 - 263250pq9r*2 - 60700p*8q*3r*3 - 386250p*5q*5r*3 + 253100p*2q*7r*3 + 127800p*9qr4 + 2326700p*6q*3r*4 + 6565550p*3q*5r*4 - 705750q*7r*4 - 2903200p*7qr5 - 21218000p*4q*3r*5 + 1057000pq5r*5 + 20368000p*5qr6 + 33000000p*2q*3r*6 - 43200000p*3qr7 + 52000000q*3r*7 + 6200p*7q*6s + 188250p4q*8s + 931500pq*10s - 73800p8q*4rs - 1466850p*5q*6rs - 6894000p*2q*8rs + 315900p*9q*2r*2s + 4547000p6q*4r*2s + 20362500p3q*6r*2s + 15018750q8r*2s - 653400p10r*3s - 13897550p7q*2r*3s - 76757500p4q*4r*3s - 124207500pq*6r*3s + 18567600p8r*4s + 175911000p5q*2r*4s + 253787500p2q*4r*4s - 183816000p6r*5s - 706900000p3q*2r*5s - 665750000q4r*5s + 740000000p4r*6s + 890000000pq*2r*6s - 1040000000p2r*7s - 763000p6q*5s*2 - 12375000p*3q*7s*2 - 40500000q*9s*2 + 364500p*10qrs*2 + 15537000p*7q*3rs2 + 154392500p*4q*5rs2 + 372206250pq7rs2 - 25481250p*8qr2s*2 - 386300000p*5q*3r*2s*2 - 996343750p*2q*5r*2s*2 + 459872500p*6qr3s*2 + 2943937500p*3q*3r*3s*2 + 2437781250q*5r*3s*2 - 2883750000p*4qr4s*2 - 4343750000pq3r*4s*2 + 5495000000p*2qr5s*2 + 1300000000qr6s*2 - 364500p*11s*3 - 13668750p*8q*2s*3 - 113406250p*5q*4s*3 - 159062500p*2q*6s*3 + 13972500p*9rs3 + 61537500p*6q*2rs3 - 1622656250p*3q*4rs3 - 2720625000q*6rs3 - 201656250p*7r*2s*3 + 1949687500p*4q*2r*2s*3 + 4979687500pq4r*2s*3 + 497125000p*5r*3s*3 - 11150625000p*2q*2r*3s*3 + 2982500000p*3r*4s*3 - 6612500000q*2r*4s*3 - 10450000000pr5s*3 + 126562500p*7qs4 + 1443750000p*4q*3s*4 + 281250000pq5s*4 - 1648125000p*5qrs*4 + 11271093750p*2q*3rs4 - 4785156250p*3qr2s*4 + 8808593750q*3r*2s*4 + 52390625000pqr*3s*4 - 611718750p*6s*5 - 13027343750p*3q*2s*5 - 1464843750q*4s*5 + 6492187500p*4rs5 - 65351562500pq2rs5 - 13476562500p*2r*2s*5 - 24218750000r*3s*5 + 41992187500p*2qs6 + 69824218750qrs*6 - 34179687500ps7 b[2][2] = -1000p*6q*7 - 5150p*3q*9 + 10800q*11 + 11000p*7q*5r + 66450p4q*7r - 127800pq*9r - 41250p8q*3r*2 - 368400p*5q*5r*2 + 204200p*2q*7r*2 + 54000p*9qr3 + 1040950p*6q*3r*3 + 2096500p*3q*5r*3 + 200000q*7r*3 - 1140000p*7qr4 - 7691000p*4q*3r*4 - 2281000pq5r*4 + 7296000p*5qr5 + 13300000p*2q*3r*5 - 14400000p*3qr6 + 14000000q*3r*6 - 9000p*8q*4s + 52100p5q*6s + 710250p2q*8s + 67500p9q*2rs - 256100p*6q*4rs - 5753000p*3q*6rs + 292500q*8rs - 162000p*10r*2s - 1432350p7q*2r*2s + 5410000p4q*4r*2s - 7408750pq*6r*2s + 4401000p8r*3s + 24185000p5q*2r*3s + 20781250p2q*4r*3s - 43012000p6r*4s - 146300000p3q*2r*4s - 165875000q4r*4s + 182000000p4r*5s + 250000000pq*2r*5s - 280000000p2r*6s + 60750p10qs2 + 2414250p*7q*3s*2 + 15770000p*4q*5s*2 + 15825000pq7s*2 - 6021000p*8qrs*2 - 62252500p*5q*3rs2 - 74718750p*2q*5rs2 + 90888750p*6qr2s*2 + 471312500p*3q*3r*2s*2 + 525875000q*5r*2s*2 - 539375000p*4qr3s*2 - 1030000000pq3r*3s*2 + 1142500000p*2qr4s*2 + 350000000qr5s*2 - 303750p*9s*3 - 35943750p*6q*2s*3 - 331875000p*3q*4s*3 - 505937500q*6s*3 + 8437500p*7rs3 + 530781250p*4q*2rs3 + 1150312500pq4rs3 - 154500000p*5r*2s*3 - 2059062500p*2q*2r*2s*3 + 1150000000p*3r*3s*3 - 1343750000q*2r*3s*3 - 2900000000pr4s*3 + 30937500p*5qs4 + 1166406250p*2q*3s*4 - 1496875000p*3qrs*4 + 1296875000q*3rs4 + 10640625000pqr*2s*4 - 281250000p*4s*5 - 9746093750pq2s*5 + 1269531250p*2rs5 - 7421875000r*2s*5 + 15625000000qs6 b[2][1] = -1600p*4q*7 - 10800pq9 + 9800p*5q*5r + 80550p2q*7r - 4600p6q*3r*2 - 112700p*3q*5r*2 + 40500q*7r*2 - 34200p*7qr3 - 279500p*4q*3r*3 - 665750pq5r*3 + 632000p*5qr4 + 3200000p*2q*3r*4 - 2800000p*3qr5 + 3000000q*3r*5 - 18600p*6q*4s - 51750p3q*6s + 405000q8s + 21600p7q*2rs - 122500p*4q*4rs - 2891250pq6rs + 156600p*8r*2s + 1569750p5q*2r*2s + 6943750p2q*4r*2s - 3774000p6r*3s - 27100000p3q*2r*3s - 30187500q4r*3s + 28000000p4r*4s + 52500000pq*2r*4s - 60000000p2r*5s - 81000p8qs2 - 240000p*5q*3s*2 + 937500p*2q*5s*2 + 3273750p*6qrs*2 + 30406250p*3q*3rs2 + 55687500q*5rs2 - 42187500p*4qr2s*2 - 112812500pq3r*2s*2 + 152500000p*2qr3s*2 + 75000000qr4s*2 - 4218750p*4q*2s*3 + 15156250pq4s*3 + 5906250p*5rs3 - 206562500p*2q*2rs3 + 107500000p*3r*2s*3 - 159375000q*2r*2s*3 - 612500000pr3s*3 + 135937500p*3qs4 + 46875000q*3s*4 + 1175781250pqrs4 - 292968750p*2s*5 - 1367187500rs5 b[2][0] = -800p*5q*5 - 5400p*2q*7 + 6000p*6q*3r + 51700p3q*5r + 27000q7r - 10800p7qr2 - 163250p*4q*3r*2 - 285750pq5r*2 + 192000p*5qr3 + 1000000p*2q*3r*3 - 800000p*3qr4 + 500000q*3r*4 - 10800p*7q*2s - 57500p4q*4s + 67500pq*6s + 32400p8rs + 279000p*5q*2rs - 131250p*2q*4rs - 729000p*6r*2s - 4100000p3q*2r*2s - 5343750q4r*2s + 5000000p4r*3s + 10000000pq*2r*3s - 10000000p2r*4s + 641250p6qs2 + 5812500p*3q*3s*2 + 10125000q*5s*2 - 7031250p*4qrs*2 - 20625000pq3rs2 + 17500000p*2qr2s*2 + 12500000qr3s*2 - 843750p*5s*3 - 19375000p*2q*2s*3 + 30000000p*3rs3 - 20312500q*2rs3 - 112500000pr2s*3 + 183593750pqs*4 - 292968750s*5 b[3][5] = 500p*11q*6 + 9875p*8q*8 + 42625p*5q*10 - 35000p*2q*12 - 4500p*12q*4r - 108375p9q*6r - 516750p6q*8r + 1110500p3q*10r + 2730000q12r + 10125p13q*2r*2 + 358250p*10q*4r*2 + 1908625p*7q*6r*2 - 11744250p*4q*8r*2 - 43383250pq10r*2 - 313875p*11q*2r*3 - 2074875p*8q*4r*3 + 52094750p*5q*6r*3 + 264567500p*2q*8r*3 + 796125p*9q*2r*4 - 92486250p*6q*4r*4 - 757957500p*3q*6r*4 - 29354375q*8r*4 + 60970000p*7q*2r*5 + 1112462500p*4q*4r*5 + 571094375pq6r*5 - 685290000p*5q*2r*6 - 2037800000p*2q*4r*6 + 2279600000p*3q*2r*7 + 849000000q*4r*7 - 1480000000pq2r*8 + 13500p*13q*3s + 363000p10q*5s + 2861250p7q*7s + 8493750p4q*9s + 17031250pq*11s - 60750p14qrs - 2319750p11q*3rs - 22674250p*8q*5rs - 74368750p*5q*7rs - 170578125p*2q*9rs + 2760750p*12qr2s + 46719000p9q*3r*2s + 163356375p6q*5r*2s + 360295625p3q*7r*2s - 195990625q9r*2s - 37341750p10qr3s - 194739375p7q*3r*3s - 105463125p4q*5r*3s - 415825000pq*7r*3s + 90180000p8qr4s - 990552500p5q*3r*4s + 3519212500p2q*5r*4s + 1112220000p6qr5s - 4508750000p3q*3r*5s - 8159500000q5r*5s - 4356000000p4qr6s + 14615000000pq*3r*6s - 2160000000p2qr7s + 91125p15s*2 + 3290625p*12q*2s*2 + 35100000p*9q*4s*2 + 175406250p*6q*6s*2 + 629062500p*3q*8s*2 + 910937500q*10s*2 - 5710500p*13rs2 - 100423125p*10q*2rs2 - 604743750p*7q*4rs2 - 2954843750p*4q*6rs2 - 4587578125pq8rs2 + 116194500p*11r*2s*2 + 1280716250p*8q*2r*2s*2 + 7401190625p*5q*4r*2s*2 + 11619937500p*2q*6r*2s*2 - 952173125p*9r*3s*2 - 6519712500p*6q*2r*3s*2 - 10238593750p*3q*4r*3s*2 + 29984609375q*6r*3s*2 + 2558300000p*7r*4s*2 + 16225000000p*4q*2r*4s*2 - 64994140625pq4r*4s*2 + 4202250000p*5r*5s*2 + 46925000000p*2q*2r*5s*2 - 28950000000p*3r*6s*2 - 1000000000q*2r*6s*2 + 37000000000pr7s*2 - 48093750p*11qs3 - 673359375p*8q*3s*3 - 2170312500p*5q*5s*3 - 2466796875p*2q*7s*3 + 647578125p*9qrs*3 + 597031250p*6q*3rs3 - 7542578125p*3q*5rs3 - 41125000000q*7rs3 - 2175828125p*7qr2s*3 - 7101562500p*4q*3r*2s*3 + 100596875000pq5r*2s*3 - 8984687500p*5qr3s*3 - 120070312500p*2q*3r*3s*3 + 57343750000p*3qr4s*3 + 9500000000q*3r*4s*3 - 342875000000pqr*5s*3 + 400781250p*10s*4 + 8531250000p*7q*2s*4 + 34033203125p*4q*4s*4 + 42724609375pq6s*4 - 6289453125p*8rs4 - 24037109375p*5q*2rs4 - 62626953125p*2q*4rs4 + 17299218750p*6r*2s*4 + 108357421875p*3q*2r*2s*4 - 55380859375q*4r*2s*4 + 105648437500p*4r*3s*4 + 1204228515625pq2r*3s*4 - 365000000000p*2r*4s*4 + 184375000000r*5s*4 - 32080078125p*6qs5 - 98144531250p*3q*3s*5 + 93994140625q*5s*5 - 178955078125p*4qrs*5 - 1299804687500pq3rs5 + 332421875000p*2qr2s*5 - 1195312500000qr3s*5 + 72021484375p*5s*6 + 323486328125p*2q*2s*6 + 682373046875p*3rs6 + 2447509765625q*2rs6 - 3011474609375pr2s*6 + 3051757812500pqs*7 - 7629394531250s*8 b[3][4] = 1500p*9q*6 + 69625p*6q*8 + 590375p*3q*10 + 1035000q*12 - 13500p*10q*4r - 760625p7q*6r - 7904500p4q*8r - 18169250pq*10r + 30375p11q*2r*2 + 2628625p*8q*4r*2 + 37879000p*5q*6r*2 + 121367500p*2q*8r*2 - 2699250p*9q*2r*3 - 76776875p*6q*4r*3 - 403583125p*3q*6r*3 - 78865625q*8r*3 + 60907500p*7q*2r*4 + 735291250p*4q*4r*4 + 781142500pq6r*4 - 558270000p*5q*2r*5 - 2150725000p*2q*4r*5 + 2015400000p*3q*2r*6 + 1181000000q*4r*6 - 2220000000pq2r*7 + 40500p*11q*3s + 1376500p8q*5s + 9953125p5q*7s + 9765625p2q*9s - 182250p12qrs - 8859000p9q*3rs - 82854500p*6q*5rs - 71511250p*3q*7rs + 273631250q*9rs + 10233000p*10qr2s + 179627500p7q*3r*2s + 25164375p4q*5r*2s - 2927290625pq*7r*2s - 171305000p8qr3s - 544768750p5q*3r*3s + 7583437500p2q*5r*3s + 1139860000p6qr4s - 6489375000p3q*3r*4s - 9625375000q5r*4s - 1838000000p4qr5s + 19835000000pq*3r*5s - 3240000000p2qr6s + 273375p13s*2 + 9753750p*10q*2s*2 + 82575000p*7q*4s*2 + 202265625p*4q*6s*2 + 556093750pq8s*2 - 11552625p*11rs2 - 115813125p*8q*2rs2 + 630590625p*5q*4rs2 + 1347015625p*2q*6rs2 + 157578750p*9r*2s*2 - 689206250p*6q*2r*2s*2 - 4299609375p*3q*4r*2s*2 + 23896171875q*6r*2s*2 - 1022437500p*7r*3s*2 + 6648125000p*4q*2r*3s*2 - 52895312500pq4r*3s*2 + 4401750000p*5r*4s*2 + 26500000000p*2q*2r*4s*2 - 22125000000p*3r*5s*2 - 1500000000q*2r*5s*2 + 55500000000pr6s*2 - 137109375p*9qs3 - 1955937500p*6q*3s*3 - 6790234375p*3q*5s*3 - 16996093750q*7s*3 + 2146218750p*7qrs*3 + 6570312500p*4q*3rs3 + 39918750000pq5rs3 - 7673281250p*5qr2s*3 - 52000000000p*2q*3r*2s*3 + 50796875000p*3qr3s*3 + 18750000000q*3r*3s*3 - 399875000000pqr*4s*3 + 780468750p*8s*4 + 14455078125p*5q*2s*4 + 10048828125p*2q*4s*4 - 15113671875p*6rs4 + 39298828125p*3q*2rs4 - 52138671875q*4rs4 + 45964843750p*4r*2s*4 + 914414062500pq2r*2s*4 + 1953125000p*2r*3s*4 + 334375000000r*4s*4 - 149169921875p*4qs5 - 459716796875pq3s*5 - 325585937500p*2qrs*5 - 1462890625000qr2s*5 + 296630859375p*3s*6 + 1324462890625q*2s*6 + 307617187500prs*6 b[3][3] = -20750p*7q*6 - 290125p*4q*8 - 993000pq10 + 146125p*8q*4r + 2721500p5q*6r + 11833750p2q*8r - 237375p9q*2r*2 - 8167500p*6q*4r*2 - 54605625p*3q*6r*2 - 23802500q*8r*2 + 8927500p*7q*2r*3 + 131184375p*4q*4r*3 + 254695000pq6r*3 - 121561250p*5q*2r*4 - 728003125p*2q*4r*4 + 702550000p*3q*2r*5 + 597312500q*4r*5 - 1202500000pq2r*6 - 194625p*9q*3s - 1568875p6q*5s + 9685625p3q*7s + 74662500q9s + 327375p10qrs + 1280000p7q*3rs - 123703750p*4q*5rs - 850121875pq7rs - 7436250p*8qr2s + 164820000p5q*3r*2s + 2336659375p2q*5r*2s + 32202500p6qr3s - 2429765625p3q*3r*3s - 4318609375q5r*3s + 148000000p4qr4s + 9902812500pq*3r*4s - 1755000000p2qr5s + 1154250p11s*2 + 36821250p*8q*2s*2 + 372825000p*5q*4s*2 + 1170921875p*2q*6s*2 - 38913750p*9rs2 - 797071875p*6q*2rs2 - 2848984375p*3q*4rs2 + 7651406250q*6rs2 + 415068750p*7r*2s*2 + 3151328125p*4q*2r*2s*2 - 17696875000pq4r*2s*2 - 725968750p*5r*3s*2 + 5295312500p*2q*2r*3s*2 - 8581250000p*3r*4s*2 - 812500000q*2r*4s*2 + 30062500000pr5s*2 - 110109375p*7qs3 - 1976562500p*4q*3s*3 - 6329296875pq5s*3 + 2256328125p*5qrs*3 + 8554687500p*2q*3rs3 + 12947265625p*3qr2s*3 + 7984375000q*3r*2s*3 - 167039062500pqr*3s*3 + 1181250000p*6s*4 + 17873046875p*3q*2s*4 - 20449218750q*4s*4 - 16265625000p*4rs4 + 260869140625pq2rs4 + 21025390625p*2r*2s*4 + 207617187500r*3s*4 - 207177734375p*2qs5 - 615478515625qrs*5 + 301513671875ps6 b[3][2] = 53125p*5q*6 + 425000p*2q*8 - 394375p*6q*4r - 4301875p3q*6r - 3225000q8r + 851250p7q*2r*2 + 16910625p*4q*4r*2 + 44210000pq6r*2 - 20474375p*5q*2r*3 - 147190625p*2q*4r*3 + 163975000p*3q*2r*4 + 156812500q*4r*4 - 323750000pq2r*5 - 99375p*7q*3s - 6395000p4q*5s - 49243750pq*7s - 1164375p8qrs + 4465625p5q*3rs + 205546875p*2q*5rs + 12163750p*6qr2s - 315546875p3q*3r*2s - 946453125q5r*2s - 23500000p4qr3s + 2313437500pq*3r*3s - 472500000p2qr4s + 1316250p9s*2 + 22715625p*6q*2s*2 + 206953125p*3q*4s*2 + 1220000000q*6s*2 - 20953125p*7rs2 - 277656250p*4q*2rs2 - 3317187500pq4rs2 + 293734375p*5r*2s*2 + 1351562500p*2q*2r*2s*2 - 2278125000p*3r*3s*2 - 218750000q*2r*3s*2 + 8093750000pr4s*2 - 9609375p*5qs3 + 240234375p*2q*3s*3 + 2310546875p*3qrs*3 + 1171875000q*3rs3 - 33460937500pqr*2s*3 + 2185546875p*4s*4 + 32578125000pq2s*4 - 8544921875p*2rs4 + 58398437500r*2s*4 - 114013671875qs5 b[3][1] = -16250p*6q*4 - 191875p*3q*6 - 495000q*8 + 73125p*7q*2r + 1437500p4q*4r + 5866250pq*6r - 2043125p5q*2r*2 - 17218750p*2q*4r*2 + 19106250p*3q*2r*3 + 34015625q*4r*3 - 69375000pq2r*4 - 219375p*8qs - 2846250p*5q*3s - 8021875p2q*5s + 3420000p6qrs - 1640625p3q*3rs - 152468750q*5rs + 3062500p*4qr2s + 381171875pq*3r*2s - 101250000p2qr3s + 2784375p7s*2 + 43515625p*4q*2s*2 + 115625000pq4s*2 - 48140625p*5rs2 - 307421875p*2q*2rs2 - 25781250p*3r*2s*2 - 46875000q*2r*2s*2 + 1734375000pr3s*2 - 128906250p*3qs3 + 339843750q*3s*3 - 4583984375pqrs3 + 2236328125p*2s*4 + 12255859375rs4 b[3][0] = 31875p*4q*4 + 255000pq6 - 82500p*5q*2r - 1106250p2q*4r + 1653125p3q*2r*2 + 5187500q*4r*2 - 11562500pq2r*3 - 118125p*6qs - 3593750p*3q*3s - 23812500q5s + 4656250p4qrs + 67109375pq*3rs - 16875000p*2qr2s - 984375p5s*2 - 19531250p*2q*2s*2 - 37890625p*3rs2 - 7812500q*2rs2 + 289062500pr2s*2 - 529296875pqs*3 + 2343750000s*4 b[4][5] = 600p*10q*10 + 13850p*7q*12 + 106150p*4q*14 + 270000pq16 - 9300p*11q*8r - 234075p8q*10r - 1942825p5q*12r - 5319900p2q*14r + 52050p12q*6r*2 + 1481025p*9q*8r*2 + 13594450p*6q*10r*2 + 40062750p*3q*12r*2 - 3569400q*14r*2 - 122175p*13q*4r*3 - 4260350p*10q*6r*3 - 45052375p*7q*8r*3 - 142634900p*4q*10r*3 + 54186350pq12r*3 + 97200p*14q*2r*4 + 5284225p*11q*4r*4 + 70389525p*8q*6r*4 + 232732850p*5q*8r*4 - 318849400p*2q*10r*4 - 2046000p*12q*2r*5 - 43874125p*9q*4r*5 - 107411850p*6q*6r*5 + 948310700p*3q*8r*5 - 34763575q*10r*5 + 5915600p*10q*2r*6 - 115887800p*7q*4r*6 - 1649542400p*4q*6r*6 + 224468875pq8r*6 + 120252800p*8q*2r*7 + 1779902000p*5q*4r*7 - 288250000p*2q*6r*7 - 915200000p*6q*2r*8 - 1164000000p*3q*4r*8 - 444200000q*6r*8 + 2502400000p*4q*2r*9 + 1984000000pq4r*9 - 2880000000p*2q*2r*10 + 20700p*12q*7s + 551475p9q*9s + 5194875p6q*11s + 18985000p3q*13s + 16875000q15s - 218700p13q*5rs - 6606475p*10q*7rs - 69770850p*7q*9rs - 285325500p*4q*11rs - 292005000pq13rs + 694575p*14q*3r*2s + 26187750p11q*5r*2s + 328992825p8q*7r*2s + 1573292400p5q*9r*2s + 1930043875p2q*11r*2s - 583200p15qr3s - 37263225p12q*3r*3s - 638579425p9q*5r*3s - 3920212225p6q*7r*3s - 6327336875p3q*9r*3s + 440969375q11r*3s + 13446000p13qr4s + 462330325p10q*3r*4s + 4509088275p7q*5r*4s + 11709795625p4q*7r*4s - 3579565625pq*9r*4s - 85033600p11qr5s - 2136801600p8q*3r*5s - 12221575800p5q*5r*5s + 9431044375p2q*7r*5s + 10643200p9qr6s + 4565594000p6q*3r*6s - 1778590000p3q*5r*6s + 4842175000q7r*6s + 712320000p7qr7s - 16182000000p4q*3r*7s - 21918000000pq*5r*7s - 742400000p5qr8s + 31040000000p2q*3r*8s + 1280000000p3qr9s + 4800000000q3r*9s + 230850p14q*4s*2 + 7373250p*11q*6s*2 + 85045625p*8q*8s*2 + 399140625p*5q*10s*2 + 565031250p*2q*12s*2 - 1257525p*15q*2rs2 - 52728975p*12q*4rs2 - 743466375p*9q*6rs2 - 4144915000p*6q*8rs2 - 7102690625p*3q*10rs2 - 1389937500q*12rs2 + 874800p*16r*2s*2 + 89851275p*13q*2r*2s*2 + 1897236775p*10q*4r*2s*2 + 14144163000p*7q*6r*2s*2 + 31942921875p*4q*8r*2s*2 + 13305118750pq10r*2s*2 - 23004000p*14r*3s*2 - 1450715475p*11q*2r*3s*2 - 19427105000p*8q*4r*3s*2 - 70634028750p*5q*6r*3s*2 - 47854218750p*2q*8r*3s*2 + 204710400p*12r*4s*2 + 10875135000p*9q*2r*4s*2 + 83618806250p*6q*4r*4s*2 + 62744500000p*3q*6r*4s*2 - 19806718750q*8r*4s*2 - 757094800p*10r*5s*2 - 37718030000p*7q*2r*5s*2 - 22479500000p*4q*4r*5s*2 + 91556093750pq6r*5s*2 + 2306320000p*8r*6s*2 + 55539600000p*5q*2r*6s*2 - 112851250000p*2q*4r*6s*2 - 10720000000p*6r*7s*2 - 64720000000p*3q*2r*7s*2 - 59925000000q*4r*7s*2 + 28000000000p*4r*8s*2 + 28000000000pq2r*8s*2 - 24000000000p*2r*9s*2 + 820125p*16qs3 + 36804375p*13q*3s*3 + 552225000p*10q*5s*3 + 3357593750p*7q*7s*3 + 7146562500p*4q*9s*3 + 3851562500pq11s*3 - 92400750p*14qrs*3 - 2350175625p*11q*3rs3 - 19470640625p*8q*5rs3 - 52820593750p*5q*7rs3 - 45447734375p*2q*9rs3 + 1824363000p*12qr2s*3 + 31435234375p*9q*3r*2s*3 + 141717537500p*6q*5r*2s*3 + 228370781250p*3q*7r*2s*3 + 34610078125q*9r*2s*3 - 17591825625p*10qr3s*3 - 188927187500p*7q*3r*3s*3 - 502088984375p*4q*5r*3s*3 - 187849296875pq7r*3s*3 + 75577750000p*8qr4s*3 + 342800000000p*5q*3r*4s*3 + 295384296875p*2q*5r*4s*3 - 107681250000p*6qr5s*3 + 53330000000p*3q*3r*5s*3 + 271586875000q*5r*5s*3 - 26410000000p*4qr6s*3 - 188200000000pq3r*6s*3 + 92000000000p*2qr7s*3 + 120000000000qr8s*3 + 47840625p*15s*4 + 1150453125p*12q*2s*4 + 9229453125p*9q*4s*4 + 24954687500p*6q*6s*4 + 22978515625p*3q*8s*4 + 1367187500q*10s*4 - 1193737500p*13rs4 - 20817843750p*10q*2rs4 - 98640000000p*7q*4rs4 - 225767187500p*4q*6rs4 - 74707031250pq8rs4 + 13431318750p*11r*2s*4 + 188709843750p*8q*2r*2s*4 + 875157656250p*5q*4r*2s*4 + 593812890625p*2q*6r*2s*4 - 69869296875p*9r*3s*4 - 854811093750p*6q*2r*3s*4 - 1730658203125p*3q*4r*3s*4 - 570867187500q*6r*3s*4 + 162075625000p*7r*4s*4 + 1536375000000p*4q*2r*4s*4 + 765156250000pq4r*4s*4 - 165988750000p*5r*5s*4 - 728968750000p*2q*2r*5s*4 + 121500000000p*3r*6s*4 - 1039375000000q*2r*6s*4 - 100000000000pr7s*4 - 379687500p*11qs5 - 11607421875p*8q*3s*5 - 20830078125p*5q*5s*5 - 33691406250p*2q*7s*5 - 41491406250p*9qrs*5 - 419054687500p*6q*3rs5 - 129511718750p*3q*5rs5 + 311767578125q*7rs5 + 620116015625p*7qr2s*5 + 1154687500000p*4q*3r*2s*5 + 36455078125pq5r*2s*5 - 2265953125000p*5qr3s*5 - 1509521484375p*2q*3r*3s*5 + 2530468750000p*3qr4s*5 + 3259765625000q*3r*4s*5 + 93750000000pqr*5s*5 + 23730468750p*10s*6 + 243603515625p*7q*2s*6 + 341552734375p*4q*4s*6 - 12207031250pq6s*6 - 357099609375p*8rs6 - 298193359375p*5q*2rs6 + 406738281250p*2q*4rs6 + 1615683593750p*6r*2s*6 + 558593750000p*3q*2r*2s*6 - 2811035156250q*4r*2s*6 - 2960937500000p*4r*3s*6 - 3802246093750pq2r*3s*6 + 2347656250000p*2r*4s*6 - 671875000000r*5s*6 - 651855468750p*6qs7 - 1458740234375p*3q*3s*7 - 152587890625q*5s*7 + 1628417968750p*4qrs*7 + 3948974609375pq3rs7 - 916748046875p*2qr2s*7 + 1611328125000qr3s*7 + 640869140625p*5s*8 + 1068115234375p*2q*2s*8 - 2044677734375p*3rs8 - 3204345703125q*2rs8 + 1739501953125pr2s*8 b[4][4] = -600p*11q*8 - 14050p*8q*10 - 109100p*5q*12 - 280800p*2q*14 + 7200p*12q*6r + 188700p9q*8r + 1621725p6q*10r + 4577075p3q*12r + 5400q14r - 28350p13q*4r*2 - 910600p*10q*6r*2 - 9237975p*7q*8r*2 - 30718900p*4q*10r*2 - 5575950pq12r*2 + 36450p*14q*2r*3 + 1848125p*11q*4r*3 + 25137775p*8q*6r*3 + 109591450p*5q*8r*3 + 70627650p*2q*10r*3 - 1317150p*12q*2r*4 - 32857100p*9q*4r*4 - 219125575p*6q*6r*4 - 327565875p*3q*8r*4 - 13011875q*10r*4 + 16484150p*10q*2r*5 + 222242250p*7q*4r*5 + 642173750p*4q*6r*5 + 101263750pq8r*5 - 79345000p*8q*2r*6 - 433180000p*5q*4r*6 - 93731250p*2q*6r*6 - 74300000p*6q*2r*7 - 1057900000p*3q*4r*7 - 591175000q*6r*7 + 1891600000p*4q*2r*8 + 2796000000pq4r*8 - 4320000000p*2q*2r*9 - 16200p*13q*5s - 359500p10q*7s - 2603825p7q*9s - 4590375p4q*11s + 12352500pq*13s + 121500p14q*3rs + 3227400p*11q*5rs + 27301725p*8q*7rs + 59480975p*5q*9rs - 137308875p*2q*11rs - 218700p*15qr2s - 8903925p12q*3r*2s - 100918225p9q*5r*2s - 325291300p6q*7r*2s + 365705000p3q*9r*2s + 94342500q11r*2s + 7632900p13qr3s + 162995400p10q*3r*3s + 974558975p7q*5r*3s + 930991250p4q*7r*3s - 495368750pq*9r*3s - 97344900p11qr4s - 1406739250p8q*3r*4s - 5572526250p5q*5r*4s - 1903987500p2q*7r*4s + 678550000p9qr5s + 8176215000p6q*3r*5s + 18082050000p3q*5r*5s + 5435843750q7r*5s - 2979800000p7qr6s - 29163500000p4q*3r*6s - 27417500000pq*5r*6s + 6282400000p5qr7s + 48690000000p2q*3r*7s - 2880000000p3qr8s + 7200000000q3r*8s - 109350p15q*2s*2 - 2405700p*12q*4s*2 - 16125250p*9q*6s*2 - 4930000p*6q*8s*2 + 201150000p*3q*10s*2 - 243000000q*12s*2 + 328050p*16rs2 + 10552275p*13q*2rs2 + 88019100p*10q*4rs2 - 4208625p*7q*6rs2 - 1920390625p*4q*8rs2 + 1759537500pq10rs2 - 11955600p*14r*2s*2 - 196375050p*11q*2r*2s*2 - 555196250p*8q*4r*2s*2 + 4213270000p*5q*6r*2s*2 - 157468750p*2q*8r*2s*2 + 162656100p*12r*3s*2 + 1880870000p*9q*2r*3s*2 + 753684375p*6q*4r*3s*2 - 25423062500p*3q*6r*3s*2 - 14142031250q*8r*3s*2 - 1251948750p*10r*4s*2 - 12524475000p*7q*2r*4s*2 + 18067656250p*4q*4r*4s*2 + 60531875000pq6r*4s*2 + 6827725000p*8r*5s*2 + 57157000000p*5q*2r*5s*2 - 75844531250p*2q*4r*5s*2 - 24452500000p*6r*6s*2 - 144950000000p*3q*2r*6s*2 - 82109375000q*4r*6s*2 + 46950000000p*4r*7s*2 + 60000000000pq2r*7s*2 - 36000000000p*2r*8s*2 + 1549125p*14qs3 + 51873750p*11q*3s*3 + 599781250p*8q*5s*3 + 2421156250p*5q*7s*3 - 1693515625p*2q*9s*3 - 104884875p*12qrs*3 - 1937437500p*9q*3rs3 - 11461053125p*6q*5rs3 + 10299375000p*3q*7rs3 + 10551250000q*9rs3 + 1336263750p*10qr2s*3 + 23737250000p*7q*3r*2s*3 + 57136718750p*4q*5r*2s*3 - 8288906250pq7r*2s*3 - 10907218750p*8qr3s*3 - 160615000000p*5q*3r*3s*3 - 111134687500p*2q*5r*3s*3 + 46743125000p*6qr4s*3 + 570509375000p*3q*3r*4s*3 + 274839843750q*5r*4s*3 - 73312500000p*4qr5s*3 - 145437500000pq3r*5s*3 + 8750000000p*2qr6s*3 + 180000000000qr7s*3 + 15946875p*13s*4 + 1265625p*10q*2s*4 - 3282343750p*7q*4s*4 - 38241406250p*4q*6s*4 - 40136718750pq8s*4 - 113146875p*11rs4 - 2302734375p*8q*2rs4 + 68450156250p*5q*4rs4 + 177376562500p*2q*6rs4 + 3164062500p*9r*2s*4 + 14392890625p*6q*2r*2s*4 - 543781250000p*3q*4r*2s*4 - 319769531250q*6r*2s*4 - 21048281250p*7r*3s*4 - 240687500000p*4q*2r*3s*4 - 228164062500pq4r*3s*4 + 23062500000p*5r*4s*4 + 300410156250p*2q*2r*4s*4 + 93437500000p*3r*5s*4 - 1141015625000q*2r*5s*4 - 187500000000pr6s*4 + 1761328125p*9qs5 - 3177734375p*6q*3s*5 + 60019531250p*3q*5s*5 + 108398437500q*7s*5 + 24106640625p*7qrs*5 + 429589843750p*4q*3rs5 + 410371093750pq5rs5 - 23582031250p*5qr2s*5 + 202441406250p*2q*3r*2s*5 - 383203125000p*3qr3s*5 + 2232910156250q*3r*3s*5 + 1500000000000pqr*4s*5 - 13710937500p*8s*6 - 202832031250p*5q*2s*6 - 531738281250p*2q*4s*6 + 73330078125p*6rs6 - 3906250000p*3q*2rs6 - 1275878906250q*4rs6 - 121093750000p*4r*2s*6 - 3308593750000pq2r*2s*6 + 18066406250p*2r*3s*6 - 244140625000r*4s*6 + 327148437500p*4qs7 + 1672363281250pq3s*7 + 446777343750p*2qrs*7 + 1232910156250qr2s*7 - 274658203125p*3s*8 - 1068115234375q*2s*8 - 61035156250prs*8 b[4][3] = 200p*9q*8 + 7550p*6q*10 + 78650p*3q*12 + 248400q*14 - 4800p*10q*6r - 164300p7q*8r - 1709575p4q*10r - 5566500pq*12r + 31050p11q*4r*2 + 1116175p*8q*6r*2 + 12674650p*5q*8r*2 + 45333850p*2q*10r*2 - 60750p*12q*2r*3 - 2872725p*9q*4r*3 - 40403050p*6q*6r*3 - 173564375p*3q*8r*3 - 11242250q*10r*3 + 2174100p*10q*2r*4 + 54010000p*7q*4r*4 + 331074875p*4q*6r*4 + 114173750pq8r*4 - 24858500p*8q*2r*5 - 300875000p*5q*4r*5 - 319430625p*2q*6r*5 + 69810000p*6q*2r*6 - 23900000p*3q*4r*6 - 294662500q*6r*6 + 524200000p*4q*2r*7 + 1432000000pq4r*7 - 2340000000p*2q*2r*8 + 5400p*11q*5s + 310400p8q*7s + 3591725p5q*9s + 11556750p2q*11s - 105300p12q*3rs - 4234650p*9q*5rs - 49928875p*6q*7rs - 174078125p*3q*9rs + 18000000q*11rs + 364500p*13qr2s + 15763050p10q*3r*2s + 220187400p7q*5r*2s + 929609375p4q*7r*2s - 43653125pq*9r*2s - 13427100p11qr3s - 346066250p8q*3r*3s - 2287673375p5q*5r*3s - 1403903125p2q*7r*3s + 184586000p9qr4s + 2983460000p6q*3r*4s + 8725818750p3q*5r*4s + 2527734375q7r*4s - 1284480000p7qr5s - 13138250000p4q*3r*5s - 14001625000pq*5r*5s + 4224800000p5qr6s + 27460000000p2q*3r*6s - 3760000000p3qr7s + 3900000000q3r*7s + 36450p13q*2s*2 + 2765475p*10q*4s*2 + 34027625p*7q*6s*2 + 97375000p*4q*8s*2 - 88275000pq10s*2 - 546750p*14rs2 - 21961125p*11q*2rs2 - 273059375p*8q*4rs2 - 761562500p*5q*6rs2 + 1869656250p*2q*8rs2 + 20545650p*12r*2s*2 + 473934375p*9q*2r*2s*2 + 1758053125p*6q*4r*2s*2 - 8743359375p*3q*6r*2s*2 - 4154375000q*8r*2s*2 - 296559000p*10r*3s*2 - 4065056250p*7q*2r*3s*2 - 186328125p*4q*4r*3s*2 + 19419453125pq6r*3s*2 + 2326262500p*8r*4s*2 + 21189375000p*5q*2r*4s*2 - 26301953125p*2q*4r*4s*2 - 10513250000p*6r*5s*2 - 69937500000p*3q*2r*5s*2 - 42257812500q*4r*5s*2 + 23375000000p*4r*6s*2 + 40750000000pq2r*6s*2 - 19500000000p*2r*7s*2 + 4009500p*12qs3 + 36140625p*9q*3s*3 - 335459375p*6q*5s*3 - 2695312500p*3q*7s*3 - 1486250000q*9s*3 + 102515625p*10qrs*3 + 4006812500p*7q*3rs3 + 27589609375p*4q*5rs3 + 20195312500pq7rs3 - 2792812500p*8qr2s*3 - 44115156250p*5q*3r*2s*3 - 72609453125p*2q*5r*2s*3 + 18752500000p*6qr3s*3 + 218140625000p*3q*3r*3s*3 + 109940234375q*5r*3s*3 - 21893750000p*4qr4s*3 - 65187500000pq3r*4s*3 - 31000000000p*2qr5s*3 + 97500000000qr6s*3 - 86568750p*11s*4 - 1955390625p*8q*2s*4 - 8960781250p*5q*4s*4 - 1357812500p*2q*6s*4 + 1657968750p*9rs4 + 10467187500p*6q*2rs4 - 55292968750p*3q*4rs4 - 60683593750q*6rs4 - 11473593750p*7r*2s*4 - 123281250000p*4q*2r*2s*4 - 164912109375pq4r*2s*4 + 13150000000p*5r*3s*4 + 190751953125p*2q*2r*3s*4 + 61875000000p*3r*4s*4 - 467773437500q*2r*4s*4 - 118750000000pr5s*4 + 7583203125p*7qs5 + 54638671875p*4q*3s*5 + 39423828125pq5s*5 + 32392578125p*5qrs*5 + 278515625000p*2q*3rs5 - 298339843750p*3qr2s*5 + 560791015625q*3r*2s*5 + 720703125000pqr*3s*5 - 19687500000p*6s*6 - 159667968750p*3q*2s*6 - 72265625000q*4s*6 + 116699218750p*4rs6 - 924072265625pq2rs6 - 156005859375p*2r*2s*6 - 112304687500r*3s*6 + 349121093750p*2qs7 + 396728515625qrs*7 - 213623046875ps8 b[4][2] = -600p*10q*6 - 18450p*7q*8 - 174000p*4q*10 - 518400pq12 + 5400p*11q*4r + 197550p8q*6r + 2147775p5q*8r + 7219800p2q*10r - 12150p12q*2r*2 - 662200p*9q*4r*2 - 9274775p*6q*6r*2 - 38330625p*3q*8r*2 - 5508000q*10r*2 + 656550p*10q*2r*3 + 16233750p*7q*4r*3 + 97335875p*4q*6r*3 + 58271250pq8r*3 - 9845500p*8q*2r*4 - 119464375p*5q*4r*4 - 194431875p*2q*6r*4 + 49465000p*6q*2r*5 + 166000000p*3q*4r*5 - 80793750q*6r*5 + 54400000p*4q*2r*6 + 377750000pq4r*6 - 630000000p*2q*2r*7 - 16200p*12q*3s - 459300p9q*5s - 4207225p6q*7s - 10827500p3q*9s + 13635000q11s + 72900p13qrs + 2877300p10q*3rs + 33239700p*7q*5rs + 107080625p*4q*7rs - 114975000pq9rs - 3601800p*11qr2s - 75214375p8q*3r*2s - 387073250p5q*5r*2s + 55540625p2q*7r*2s + 53793000p9qr3s + 687176875p6q*3r*3s + 1670018750p3q*5r*3s + 665234375q7r*3s - 391570000p7qr4s - 3420125000p4q*3r*4s - 3609625000pq*5r*4s + 1365600000p5qr5s + 7236250000p2q*3r*5s - 1220000000p3qr6s + 1050000000q3r*6s - 109350p14s*2 - 3065850p*11q*2s*2 - 26908125p*8q*4s*2 - 44606875p*5q*6s*2 + 269812500p*2q*8s*2 + 5200200p*12rs2 + 81826875p*9q*2rs2 + 155378125p*6q*4rs2 - 1936203125p*3q*6rs2 - 998437500q*8rs2 - 77145750p*10r*2s*2 - 745528125p*7q*2r*2s*2 + 683437500p*4q*4r*2s*2 + 4083359375pq6r*2s*2 + 593287500p*8r*3s*2 + 4799375000p*5q*2r*3s*2 - 4167578125p*2q*4r*3s*2 - 2731125000p*6r*4s*2 - 18668750000p*3q*2r*4s*2 - 10480468750q*4r*4s*2 + 6200000000p*4r*5s*2 + 11750000000pq2r*5s*2 - 5250000000p*2r*6s*2 + 26527500p*10qs3 + 526031250p*7q*3s*3 + 3160703125p*4q*5s*3 + 2650312500pq7s*3 - 448031250p*8qrs*3 - 6682968750p*5q*3rs3 - 11642812500p*2q*5rs3 + 2553203125p*6qr2s*3 + 37234375000p*3q*3r*2s*3 + 21871484375q*5r*2s*3 + 2803125000p*4qr3s*3 - 10796875000pq3r*3s*3 - 16656250000p*2qr4s*3 + 26250000000qr5s*3 - 75937500p*9s*4 - 704062500p*6q*2s*4 - 8363281250p*3q*4s*4 - 10398437500q*6s*4 + 197578125p*7rs4 - 16441406250p*4q*2rs4 - 24277343750pq4rs4 - 5716015625p*5r*2s*4 + 31728515625p*2q*2r*2s*4 + 27031250000p*3r*3s*4 - 92285156250q*2r*3s*4 - 33593750000pr4s*4 + 10394531250p*5qs5 + 38037109375p*2q*3s*5 - 48144531250p*3qrs*5 + 74462890625q*3rs5 + 121093750000pqr*2s*5 - 2197265625p*4s*6 - 92529296875pq2s*6 + 15380859375p*2rs6 - 31738281250r*2s*6 + 54931640625qs7 b[4][1] = 200p*8q*6 + 2950p*5q*8 + 10800p*2q*10 - 1800p*9q*4r - 49650p6q*6r - 403375p3q*8r - 999000q10r + 4050p10q*2r*2 + 236625p*7q*4r*2 + 3109500p*4q*6r*2 + 11463750pq8r*2 - 331500p*8q*2r*3 - 7818125p*5q*4r*3 - 41411250p*2q*6r*3 + 4782500p*6q*2r*4 + 47475000p*3q*4r*4 - 16728125q*6r*4 - 8700000p*4q*2r*5 + 81750000pq4r*5 - 135000000p*2q*2r*6 + 5400p*10q*3s + 144200p7q*5s + 939375p4q*7s + 1012500pq*9s - 24300p11qrs - 1169250p8q*3rs - 14027250p*5q*5rs - 44446875p*2q*7rs + 2011500p*9qr2s + 49330625p6q*3r*2s + 272009375p3q*5r*2s + 104062500q7r*2s - 34660000p7qr3s - 455062500p4q*3r*3s - 625906250pq*5r*3s + 210200000p5qr4s + 1298750000p2q*3r*4s - 240000000p3qr5s + 225000000q3r*5s + 36450p12s*2 + 1231875p*9q*2s*2 + 10712500p*6q*4s*2 + 21718750p*3q*6s*2 + 16875000q*8s*2 - 2814750p*10rs2 - 67612500p*7q*2rs2 - 345156250p*4q*4rs2 - 283125000pq6rs2 + 51300000p*8r*2s*2 + 734531250p*5q*2r*2s*2 + 1267187500p*2q*4r*2s*2 - 384312500p*6r*3s*2 - 3912500000p*3q*2r*3s*2 - 1822265625q*4r*3s*2 + 1112500000p*4r*4s*2 + 2437500000pq2r*4s*2 - 1125000000p*2r*5s*2 - 72578125p*5q*3s*3 - 189296875p*2q*5s*3 + 127265625p*6qrs*3 + 1415625000p*3q*3rs3 + 1229687500q*5rs3 + 1448437500p*4qr2s*3 + 2218750000pq3r*2s*3 - 4031250000p*2qr3s*3 + 5625000000qr4s*3 - 132890625p*7s*4 - 529296875p*4q*2s*4 - 175781250pq4s*4 - 401953125p*5rs4 - 4482421875p*2q*2rs4 + 4140625000p*3r*2s*4 - 10498046875q*2r*2s*4 - 7031250000pr3s*4 + 1220703125p*3qs5 + 1953125000q*3s*5 + 14160156250pqrs5 - 1708984375p*2s*6 - 3662109375rs6 b[4][0] = -4600p*6q*6 - 67850p*3q*8 - 248400q*10 + 38900p*7q*4r + 679575p4q*6r + 2866500pq*8r - 81900p8q*2r*2 - 2009750p*5q*4r*2 - 10783750p*2q*6r*2 + 1478750p*6q*2r*3 + 14165625p*3q*4r*3 - 2743750q*6r*3 - 5450000p*4q*2r*4 + 12687500pq4r*4 - 22500000p*2q*2r*5 - 101700p*8q*3s - 1700975p5q*5s - 7061250p2q*7s + 423900p9qrs + 9292375p6q*3rs + 50438750p*3q*5rs + 20475000q*7rs - 7852500p*7qr2s - 87765625p4q*3r*2s - 121609375pq*5r*2s + 47700000p5qr3s + 264687500p2q*3r*3s - 65000000p3qr4s + 37500000q3r*4s - 534600p10s*2 - 10344375p*7q*2s*2 - 54859375p*4q*4s*2 - 40312500pq6s*2 + 10158750p*8rs2 + 117778125p*5q*2rs2 + 192421875p*2q*4rs2 - 70593750p*6r*2s*2 - 685312500p*3q*2r*2s*2 - 334375000q*4r*2s*2 + 193750000p*4r*3s*2 + 500000000pq2r*3s*2 - 187500000p*2r*4s*2 + 8437500p*6qs3 + 159218750p*3q*3s*3 + 220625000q*5s*3 + 353828125p*4qrs*3 + 412500000pq3rs3 - 1023437500p*2qr2s*3 + 937500000qr3s*3 - 206015625p*5s*4 - 701171875p*2q*2s*4 + 998046875p*3rs4 - 1308593750q*2rs4 - 1367187500pr2s*4 + 1708984375pqs*5 - 976562500s*6 return b @property def o(self): p, q, r, s = self.p, self.q, self.r, self.s o = [0]6 o[5] = -1600p10q*10 - 23600p*7q*12 - 86400p*4q*14 + 24800p*11q*8r + 419200p8q*10r + 1850450p5q*12r + 896400p2q*14r - 138800p12q*6r*2 - 2921900p*9q*8r*2 - 17295200p*6q*10r*2 - 27127750p*3q*12r*2 - 26076600q*14r*2 + 325800p*13q*4r*3 + 9993850p*10q*6r*3 + 88010500p*7q*8r*3 + 274047650p*4q*10r*3 + 410171400pq12r*3 - 259200p*14q*2r*4 - 17147100p*11q*4r*4 - 254289150p*8q*6r*4 - 1318548225p*5q*8r*4 - 2633598475p*2q*10r*4 + 12636000p*12q*2r*5 + 388911000p*9q*4r*5 + 3269704725p*6q*6r*5 + 8791192300p*3q*8r*5 + 93560575q*10r*5 - 228361600p*10q*2r*6 - 3951199200p*7q*4r*6 - 16276981100p*4q*6r*6 - 1597227000pq8r*6 + 1947899200p*8q*2r*7 + 17037648000p*5q*4r*7 + 8919740000p*2q*6r*7 - 7672160000p*6q*2r*8 - 15496000000p*3q*4r*8 + 4224000000q*6r*8 + 9968000000p*4q*2r*9 - 8640000000pq4r*9 + 4800000000p*2q*2r*10 - 55200p*12q*7s - 685600p9q*9s + 1028250p6q*11s + 37650000p3q*13s + 111375000q15s + 583200p13q*5rs + 9075600p*10q*7rs - 883150p*7q*9rs - 506830750p*4q*11rs - 1793137500pq13rs - 1852200p*14q*3r*2s - 41435250p11q*5r*2s - 80566700p8q*7r*2s + 2485673600p5q*9r*2s + 11442286125p2q*11r*2s + 1555200p15qr3s + 80846100p12q*3r*3s + 564906800p9q*5r*3s - 4493012400p6q*7r*3s - 35492391250p3q*9r*3s - 789931875q11r*3s - 71766000p13qr4s - 1551149200p10q*3r*4s - 1773437900p7q*5r*4s + 51957593125p4q*7r*4s + 14964765625pq*9r*4s + 1231569600p11qr5s + 12042977600p8q*3r*5s - 27151011200p5q*5r*5s - 88080610000p2q*7r*5s - 9912995200p9qr6s - 29448104000p6q*3r*6s + 144954840000p3q*5r*6s - 44601300000q7r*6s + 35453760000p7qr7s - 63264000000p4q*3r*7s + 60544000000pq*5r*7s - 30048000000p5qr8s + 37040000000p2q*3r*8s - 60800000000p3qr9s - 48000000000q3r*9s - 615600p14q*4s*2 - 10524500p*11q*6s*2 - 33831250p*8q*8s*2 + 222806250p*5q*10s*2 + 1099687500p*2q*12s*2 + 3353400p*15q*2rs2 + 74269350p*12q*4rs2 + 276445750p*9q*6rs2 - 2618600000p*6q*8rs2 - 14473243750p*3q*10rs2 + 1383750000q*12rs2 - 2332800p*16r*2s*2 - 132750900p*13q*2r*2s*2 - 900775150p*10q*4r*2s*2 + 8249244500p*7q*6r*2s*2 + 59525796875p*4q*8r*2s*2 - 40292868750pq10r*2s*2 + 128304000p*14r*3s*2 + 3160232100p*11q*2r*3s*2 + 8329580000p*8q*4r*3s*2 - 45558458750p*5q*6r*3s*2 + 297252890625p*2q*8r*3s*2 - 2769854400p*12r*4s*2 - 37065970000p*9q*2r*4s*2 - 90812546875p*6q*4r*4s*2 - 627902000000p*3q*6r*4s*2 + 181347421875q*8r*4s*2 + 30946932800p*10r*5s*2 + 249954680000p*7q*2r*5s*2 + 802954812500p*4q*4r*5s*2 - 80900000000pq6r*5s*2 - 192137320000p*8r*6s*2 - 932641600000p*5q*2r*6s*2 - 943242500000p*2q*4r*6s*2 + 658412000000p*6r*7s*2 + 1930720000000p*3q*2r*7s*2 + 593800000000q*4r*7s*2 - 1162800000000p*4r*8s*2 - 280000000000pq2r*8s*2 + 840000000000p*2r*9s*2 - 2187000p*16qs3 - 47418750p*13q*3s*3 - 180618750p*10q*5s*3 + 2231250000p*7q*7s*3 + 17857734375p*4q*9s*3 + 29882812500pq11s*3 + 24664500p*14qrs*3 - 853368750p*11q*3rs3 - 25939693750p*8q*5rs3 - 177541562500p*5q*7rs3 - 297978828125p*2q*9rs3 - 153468000p*12qr2s*3 + 30188125000p*9q*3r*2s*3 + 344049821875p*6q*5r*2s*3 + 534026875000p*3q*7r*2s*3 - 340726484375q*9r*2s*3 - 9056190000p*10qr3s*3 - 322314687500p*7q*3r*3s*3 - 769632109375p*4q*5r*3s*3 - 83276875000pq7r*3s*3 + 164061000000p*8qr4s*3 + 1381358750000p*5q*3r*4s*3 + 3088020000000p*2q*5r*4s*3 - 1267655000000p*6qr5s*3 - 7642630000000p*3q*3r*5s*3 - 2759877500000q*5r*5s*3 + 4597760000000p*4qr6s*3 + 1846200000000pq3r*6s*3 - 7006000000000p*2qr7s*3 - 1200000000000qr8s*3 + 18225000p*15s*4 + 1328906250p*12q*2s*4 + 24729140625p*9q*4s*4 + 169467187500p*6q*6s*4 + 413281250000p*3q*8s*4 + 223828125000q*10s*4 + 710775000p*13rs4 - 18611015625p*10q*2rs4 - 314344375000p*7q*4rs4 - 828439843750p*4q*6rs4 + 460937500000pq8rs4 - 25674975000p*11r*2s*4 - 52223515625p*8q*2r*2s*4 - 387160000000p*5q*4r*2s*4 - 4733680078125p*2q*6r*2s*4 + 343911875000p*9r*3s*4 + 3328658359375p*6q*2r*3s*4 + 16532406250000p*3q*4r*3s*4 + 5980613281250q*6r*3s*4 - 2295497500000p*7r*4s*4 - 14809820312500p*4q*2r*4s*4 - 6491406250000pq4r*4s*4 + 7768470000000p*5r*5s*4 + 34192562500000p*2q*2r*5s*4 - 11859000000000p*3r*6s*4 + 10530000000000q*2r*6s*4 + 6000000000000pr7s*4 + 11453906250p*11qs5 + 149765625000p*8q*3s*5 + 545537109375p*5q*5s*5 + 527343750000p*2q*7s*5 - 371313281250p*9qrs*5 - 3461455078125p*6q*3rs5 - 7920878906250p*3q*5rs5 - 4747314453125q*7rs5 + 2417815625000p*7qr2s*5 + 5465576171875p*4q*3r*2s*5 + 5937128906250pq5r*2s*5 - 10661156250000p*5qr3s*5 - 63574218750000p*2q*3r*3s*5 + 24059375000000p*3qr4s*5 - 33023437500000q*3r*4s*5 - 43125000000000pqr*5s*5 + 94394531250p*10s*6 + 1097167968750p*7q*2s*6 + 2829833984375p*4q*4s*6 - 1525878906250pq6s*6 + 2724609375p*8rs6 + 13998535156250p*5q*2rs6 + 57094482421875p*2q*4rs6 - 8512509765625p*6r*2s*6 - 37941406250000p*3q*2r*2s*6 + 33191894531250q*4r*2s*6 + 50534179687500p*4r*3s*6 + 156656250000000pq2r*3s*6 - 85023437500000p*2r*4s*6 + 10125000000000r*5s*6 - 2717285156250p*6qs7 - 11352539062500p*3q*3s*7 - 2593994140625q*5s*7 - 47154541015625p*4qrs*7 - 160644531250000pq3rs7 + 142500000000000p*2qr2s*7 - 26757812500000qr3s*7 - 4364013671875p*5s*8 - 94604492187500p*2q*2s*8 + 114379882812500p*3rs8 + 51116943359375q*2rs8 - 346435546875000pr2s*8 + 476837158203125pqs*9 - 476837158203125s*10 o[4] = 1600p*11q*8 + 20800p*8q*10 + 45100p*5q*12 - 151200p*2q*14 - 19200p*12q*6r - 293200p9q*8r - 794600p6q*10r + 2634675p3q*12r + 2640600q14r + 75600p13q*4r*2 + 1529100p*10q*6r*2 + 6233350p*7q*8r*2 - 12013350p*4q*10r*2 - 29069550pq12r*2 - 97200p*14q*2r*3 - 3562500p*11q*4r*3 - 26984900p*8q*6r*3 - 15900325p*5q*8r*3 + 76267100p*2q*10r*3 + 3272400p*12q*2r*4 + 59486850p*9q*4r*4 + 221270075p*6q*6r*4 + 74065250p*3q*8r*4 - 300564375q*10r*4 - 45569400p*10q*2r*5 - 438666000p*7q*4r*5 - 444821250p*4q*6r*5 + 2448256250pq8r*5 + 290640000p*8q*2r*6 + 855850000p*5q*4r*6 - 5741875000p*2q*6r*6 - 644000000p*6q*2r*7 + 5574000000p*3q*4r*7 + 4643000000q*6r*7 - 1696000000p*4q*2r*8 - 12660000000pq4r*8 + 7200000000p*2q*2r*9 + 43200p*13q*5s + 572000p10q*7s - 59800p7q*9s - 24174625p4q*11s - 74587500pq*13s - 324000p14q*3rs - 5531400p*11q*5rs - 3712100p*8q*7rs + 293009275p*5q*9rs + 1115548875p*2q*11rs + 583200p*15qr2s + 18343800p12q*3r*2s + 77911100p9q*5r*2s - 957488825p6q*7r*2s - 5449661250p3q*9r*2s + 960120000q11r*2s - 23684400p13qr3s - 373761900p10q*3r*3s - 27944975p7q*5r*3s + 10375740625p4q*7r*3s - 4649093750pq*9r*3s + 395816400p11qr4s + 2910968000p8q*3r*4s - 9126162500p5q*5r*4s - 11696118750p2q*7r*4s - 3028640000p9qr5s - 3251550000p6q*3r*5s + 47914250000p3q*5r*5s - 30255625000q7r*5s + 9304000000p7qr6s - 42970000000p4q*3r*6s + 31475000000pq*5r*6s + 2176000000p5qr7s + 62100000000p2q*3r*7s - 43200000000p3qr8s - 72000000000q3r*8s + 291600p15q*2s*2 + 2702700p*12q*4s*2 - 38692250p*9q*6s*2 - 538903125p*6q*8s*2 - 1613112500p*3q*10s*2 + 320625000q*12s*2 - 874800p*16rs2 - 14166900p*13q*2rs2 + 193284900p*10q*4rs2 + 3688520500p*7q*6rs2 + 11613390625p*4q*8rs2 - 15609881250pq10rs2 + 44031600p*14r*2s*2 + 482345550p*11q*2r*2s*2 - 2020881875p*8q*4r*2s*2 - 7407026250p*5q*6r*2s*2 + 136175750000p*2q*8r*2s*2 - 1000884600p*12r*3s*2 - 8888950000p*9q*2r*3s*2 - 30101703125p*6q*4r*3s*2 - 319761000000p*3q*6r*3s*2 + 51519218750q*8r*3s*2 + 12622395000p*10r*4s*2 + 97032450000p*7q*2r*4s*2 + 469929218750p*4q*4r*4s*2 + 291342187500pq6r*4s*2 - 96382000000p*8r*5s*2 - 598070000000p*5q*2r*5s*2 - 1165021875000p*2q*4r*5s*2 + 446500000000p*6r*6s*2 + 1651500000000p*3q*2r*6s*2 + 789375000000q*4r*6s*2 - 1152000000000p*4r*7s*2 - 600000000000pq2r*7s*2 + 1260000000000p*2r*8s*2 - 24786000p*14qs3 - 660487500p*11q*3s*3 - 5886356250p*8q*5s*3 - 18137187500p*5q*7s*3 - 5120546875p*2q*9s*3 + 827658000p*12qrs*3 + 13343062500p*9q*3rs3 + 39782068750p*6q*5rs3 - 111288437500p*3q*7rs3 - 15438750000q*9rs3 - 14540782500p*10qr2s*3 - 135889750000p*7q*3r*2s*3 - 176892578125p*4q*5r*2s*3 - 934462656250pq7r*2s*3 + 171669250000p*8qr3s*3 + 1164538125000p*5q*3r*3s*3 + 3192346406250p*2q*5r*3s*3 - 1295476250000p*6qr4s*3 - 6540712500000p*3q*3r*4s*3 - 2957828125000q*5r*4s*3 + 5366750000000p*4qr5s*3 + 3165000000000pq3r*5s*3 - 8862500000000p*2qr6s*3 - 1800000000000qr7s*3 + 236925000p*13s*4 + 8895234375p*10q*2s*4 + 106180781250p*7q*4s*4 + 474221875000p*4q*6s*4 + 616210937500pq8s*4 - 6995868750p*11rs4 - 184190625000p*8q*2rs4 - 1299254453125p*5q*4rs4 - 2475458593750p*2q*6rs4 + 63049218750p*9r*2s*4 + 1646791484375p*6q*2r*2s*4 + 9086886718750p*3q*4r*2s*4 + 4673421875000q*6r*2s*4 - 215665000000p*7r*3s*4 - 7864589843750p*4q*2r*3s*4 - 5987890625000pq4r*3s*4 + 594843750000p*5r*4s*4 + 27791171875000p*2q*2r*4s*4 - 3881250000000p*3r*5s*4 + 12203125000000q*2r*5s*4 + 10312500000000pr6s*4 - 34720312500p*9qs5 - 545126953125p*6q*3s*5 - 2176425781250p*3q*5s*5 - 2792968750000q*7s*5 - 1395703125p*7qrs*5 - 1957568359375p*4q*3rs5 + 5122636718750pq5rs5 + 858210937500p*5qr2s*5 - 42050097656250p*2q*3r*2s*5 + 7088281250000p*3qr3s*5 - 25974609375000q*3r*3s*5 - 69296875000000pqr*4s*5 + 384697265625p*8s*6 + 6403320312500p*5q*2s*6 + 16742675781250p*2q*4s*6 - 3467080078125p*6rs6 + 11009765625000p*3q*2rs6 + 16451660156250q*4rs6 + 6979003906250p*4r*2s*6 + 145403320312500pq2r*2s*6 + 4076171875000p*2r*3s*6 + 22265625000000r*4s*6 - 21915283203125p*4qs7 - 86608886718750pq3s*7 - 22785644531250p*2qrs*7 - 103466796875000qr2s*7 + 18798828125000p*3s*8 + 106048583984375q*2s*8 + 17761230468750prs*8 o[3] = 2800p*9q*8 + 55700p*6q*10 + 363600p*3q*12 + 777600q*14 - 27200p*10q*6r - 700200p7q*8r - 5726550p4q*10r - 15066000pq*12r + 74700p11q*4r*2 + 2859575p*8q*6r*2 + 31175725p*5q*8r*2 + 103147650p*2q*10r*2 - 40500p*12q*2r*3 - 4274400p*9q*4r*3 - 76065825p*6q*6r*3 - 365623750p*3q*8r*3 - 132264000q*10r*3 + 2192400p*10q*2r*4 + 92562500p*7q*4r*4 + 799193875p*4q*6r*4 + 1188193125pq8r*4 - 41231500p*8q*2r*5 - 914210000p*5q*4r*5 - 3318853125p*2q*6r*5 + 398850000p*6q*2r*6 + 3944000000p*3q*4r*6 + 2211312500q*6r*6 - 1817000000p*4q*2r*7 - 6720000000pq4r*7 + 3900000000p*2q*2r*8 + 75600p*11q*5s + 1823100p8q*7s + 14534150p5q*9s + 38265750p2q*11s - 394200p12q*3rs - 11453850p*9q*5rs - 101213000p*6q*7rs - 223565625p*3q*9rs + 415125000q*11rs + 243000p*13qr2s + 13654575p10q*3r*2s + 163811725p7q*5r*2s + 173461250p4q*7r*2s - 3008671875pq*9r*2s - 2016900p11qr3s - 86576250p8q*3r*3s - 324146625p5q*5r*3s + 3378506250p2q*7r*3s - 89211000p9qr4s - 55207500p6q*3r*4s + 1493950000p3q*5r*4s - 12573609375q7r*4s + 1140100000p7qr5s + 42500000p4q*3r*5s + 21511250000pq*5r*5s - 4058000000p5qr6s + 6725000000p2q*3r*6s - 1400000000p3qr7s - 39000000000q3r*7s + 510300p13q*2s*2 + 4814775p*10q*4s*2 - 70265125p*7q*6s*2 - 1016484375p*4q*8s*2 - 3221100000pq10s*2 - 364500p*14rs2 + 30314250p*11q*2rs2 + 1106765625p*8q*4rs2 + 10984203125p*5q*6rs2 + 33905812500p*2q*8rs2 - 37980900p*12r*2s*2 - 2142905625p*9q*2r*2s*2 - 26896125000p*6q*4r*2s*2 - 95551328125p*3q*6r*2s*2 + 11320312500q*8r*2s*2 + 1743781500p*10r*3s*2 + 35432262500p*7q*2r*3s*2 + 177855859375p*4q*4r*3s*2 + 121260546875pq6r*3s*2 - 25943162500p*8r*4s*2 - 249165500000p*5q*2r*4s*2 - 461739453125p*2q*4r*4s*2 + 177823750000p*6r*5s*2 + 726225000000p*3q*2r*5s*2 + 404195312500q*4r*5s*2 - 565875000000p*4r*6s*2 - 407500000000pq2r*6s*2 + 682500000000p*2r*7s*2 - 59140125p*12qs3 - 1290515625p*9q*3s*3 - 8785071875p*6q*5s*3 - 15588281250p*3q*7s*3 + 17505000000q*9s*3 + 896062500p*10qrs*3 + 2589750000p*7q*3rs3 - 82700156250p*4q*5rs3 - 347683593750pq7rs3 + 17022656250p*8qr2s*3 + 320923593750p*5q*3r*2s*3 + 1042116875000p*2q*5r*2s*3 - 353262812500p*6qr3s*3 - 2212664062500p*3q*3r*3s*3 - 1252408984375q*5r*3s*3 + 1967362500000p*4qr4s*3 + 1583343750000pq3r*4s*3 - 3560625000000p*2qr5s*3 - 975000000000qr6s*3 + 462459375p*11s*4 + 14210859375p*8q*2s*4 + 99521718750p*5q*4s*4 + 114955468750p*2q*6s*4 - 17720859375p*9rs4 - 100320703125p*6q*2rs4 + 1021943359375p*3q*4rs4 + 1193203125000q*6rs4 + 171371250000p*7r*2s*4 - 1113390625000p*4q*2r*2s*4 - 1211474609375pq4r*2s*4 - 274056250000p*5r*3s*4 + 8285166015625p*2q*2r*3s*4 - 2079375000000p*3r*4s*4 + 5137304687500q*2r*4s*4 + 6187500000000pr5s*4 - 135675000000p*7qs5 - 1275244140625p*4q*3s*5 - 28388671875pq5s*5 + 1015166015625p*5qrs*5 - 10584423828125p*2q*3rs5 + 3559570312500p*3qr2s*5 - 6929931640625q*3r*2s*5 - 32304687500000pqr*3s*5 + 430576171875p*6s*6 + 9397949218750p*3q*2s*6 + 575195312500q*4s*6 - 4086425781250p*4rs6 + 42183837890625pq2rs6 + 8156494140625p*2r*2s*6 + 12612304687500r*3s*6 - 25513916015625p*2qs7 - 37017822265625qrs*7 + 18981933593750ps8 o[2] = 1600p*10q*6 + 9200p*7q*8 - 126000p*4q*10 - 777600pq12 - 14400p*11q*4r - 119300p8q*6r + 1203225p5q*8r + 9412200p2q*10r + 32400p12q*2r*2 + 417950p*9q*4r*2 - 4543725p*6q*6r*2 - 49008125p*3q*8r*2 - 24192000q*10r*2 - 292050p*10q*2r*3 + 8760000p*7q*4r*3 + 137506625p*4q*6r*3 + 225438750pq8r*3 - 4213250p*8q*2r*4 - 173595625p*5q*4r*4 - 653003125p*2q*6r*4 + 82575000p*6q*2r*5 + 838125000p*3q*4r*5 + 578562500q*6r*5 - 421500000p*4q*2r*6 - 1796250000pq4r*6 + 1050000000p*2q*2r*7 + 43200p*12q*3s + 807300p9q*5s + 5328225p6q*7s + 16946250p3q*9s + 29565000q11s - 194400p13qrs - 5505300p10q*3rs - 49886700p*7q*5rs - 178821875p*4q*7rs - 222750000pq9rs + 6814800p*11qr2s + 120525625p8q*3r*2s + 526694500p5q*5r*2s + 84065625p2q*7r*2s - 123670500p9qr3s - 1106731875p6q*3r*3s - 669556250p3q*5r*3s - 2869265625q7r*3s + 1004350000p7qr4s + 3384375000p4q*3r*4s + 5665625000pq*5r*4s - 3411000000p5qr5s - 418750000p2q*3r*5s + 1700000000p3qr6s - 10500000000q3r*6s + 291600p14s*2 + 9829350p*11q*2s*2 + 114151875p*8q*4s*2 + 522169375p*5q*6s*2 + 716906250p*2q*8s*2 - 18625950p*12rs2 - 387703125p*9q*2rs2 - 2056109375p*6q*4rs2 - 760203125p*3q*6rs2 + 3071250000q*8rs2 + 512419500p*10r*2s*2 + 5859053125p*7q*2r*2s*2 + 12154062500p*4q*4r*2s*2 + 15931640625pq6r*2s*2 - 6598393750p*8r*3s*2 - 43549625000p*5q*2r*3s*2 - 82011328125p*2q*4r*3s*2 + 43538125000p*6r*4s*2 + 160831250000p*3q*2r*4s*2 + 99070312500q*4r*4s*2 - 141812500000p*4r*5s*2 - 117500000000pq2r*5s*2 + 183750000000p*2r*6s*2 - 154608750p*10qs3 - 3309468750p*7q*3s*3 - 20834140625p*4q*5s*3 - 34731562500pq7s*3 + 5970375000p*8qrs*3 + 68533281250p*5q*3rs3 + 142698281250p*2q*5rs3 - 74509140625p*6qr2s*3 - 389148437500p*3q*3r*2s*3 - 270937890625q*5r*2s*3 + 366696875000p*4qr3s*3 + 400031250000pq3r*3s*3 - 735156250000p*2qr4s*3 - 262500000000qr5s*3 + 371250000p*9s*4 + 21315000000p*6q*2s*4 + 179515625000p*3q*4s*4 + 238406250000q*6s*4 - 9071015625p*7rs4 - 268945312500p*4q*2rs4 - 379785156250pq4rs4 + 140262890625p*5r*2s*4 + 1486259765625p*2q*2r*2s*4 - 806484375000p*3r*3s*4 + 1066210937500q*2r*3s*4 + 1722656250000pr4s*4 - 125648437500p*5qs5 - 1236279296875p*2q*3s*5 + 1267871093750p*3qrs*5 - 1044677734375q*3rs5 - 6630859375000pqr*2s*5 + 160888671875p*4s*6 + 6352294921875pq2s*6 - 708740234375p*2rs6 + 3901367187500r*2s*6 - 8050537109375qs7 o[1] = 2800p*8q*6 + 41300p*5q*8 + 151200p*2q*10 - 25200p*9q*4r - 542600p6q*6r - 3397875p3q*8r - 5751000q10r + 56700p10q*2r*2 + 1972125p*7q*4r*2 + 18624250p*4q*6r*2 + 50253750pq8r*2 - 1701000p*8q*2r*3 - 32630625p*5q*4r*3 - 139868750p*2q*6r*3 + 18162500p*6q*2r*4 + 177125000p*3q*4r*4 + 121734375q*6r*4 - 100500000p*4q*2r*5 - 386250000pq4r*5 + 225000000p*2q*2r*6 + 75600p*10q*3s + 1708800p7q*5s + 12836875p4q*7s + 32062500pq*9s - 340200p11qrs - 10185750p8q*3rs - 97502750p*5q*5rs - 301640625p*2q*7rs + 7168500p*9qr2s + 135960625p6q*3r*2s + 587471875p3q*5r*2s - 384750000q7r*2s - 29325000p7qr3s - 320625000p4q*3r*3s + 523437500pq*5r*3s - 42000000p5qr4s + 343750000p2q*3r*4s + 150000000p3qr5s - 2250000000q3r*5s + 510300p12s*2 + 12808125p*9q*2s*2 + 107062500p*6q*4s*2 + 270312500p*3q*6s*2 - 168750000q*8s*2 - 2551500p*10rs2 - 5062500p*7q*2rs2 + 712343750p*4q*4rs2 + 4788281250pq6rs2 - 256837500p*8r*2s*2 - 3574812500p*5q*2r*2s*2 - 14967968750p*2q*4r*2s*2 + 4040937500p*6r*3s*2 + 26400000000p*3q*2r*3s*2 + 17083984375q*4r*3s*2 - 21812500000p*4r*4s*2 - 24375000000pq2r*4s*2 + 39375000000p*2r*5s*2 - 127265625p*5q*3s*3 - 680234375p*2q*5s*3 - 2048203125p*6qrs*3 - 18794531250p*3q*3rs3 - 25050000000q*5rs3 + 26621875000p*4qr2s*3 + 37007812500pq3r*2s*3 - 105468750000p*2qr3s*3 - 56250000000qr4s*3 + 1124296875p*7s*4 + 9251953125p*4q*2s*4 - 8007812500pq4s*4 - 4004296875p*5rs4 + 179931640625p*2q*2rs4 - 75703125000p*3r*2s*4 + 133447265625q*2r*2s*4 + 363281250000pr3s*4 - 91552734375p*3qs5 - 19531250000q*3s*5 - 751953125000pqrs5 + 157958984375p*2s*6 + 748291015625rs6 o[0] = -14400p*6q*6 - 212400p*3q*8 - 777600q*10 + 92100p*7q*4r + 1689675p4q*6r + 7371000pq*8r - 122850p8q*2r*2 - 3735250p*5q*4r*2 - 22432500p*2q*6r*2 + 2298750p*6q*2r*3 + 29390625p*3q*4r*3 + 18000000q*6r*3 - 17750000p*4q*2r*4 - 62812500pq4r*4 + 37500000p*2q*2r*5 - 51300p*8q*3s - 768025p5q*5s - 2801250p2q*7s - 275400p9qrs - 5479875p6q*3rs - 35538750p*3q*5rs - 68850000q*7rs + 12757500p*7qr2s + 133640625p4q*3r*2s + 222609375pq*5r*2s - 108500000p5qr3s - 290312500p2q*3r*3s + 275000000p3qr4s - 375000000q3r*4s + 1931850p10s*2 + 40213125p*7q*2s*2 + 253921875p*4q*4s*2 + 464062500pq6s*2 - 71077500p*8rs2 - 818746875p*5q*2rs2 - 1882265625p*2q*4rs2 + 826031250p*6r*2s*2 + 4369687500p*3q*2r*2s*2 + 3107812500q*4r*2s*2 - 3943750000p*4r*3s*2 - 5000000000pq2r*3s*2 + 6562500000p*2r*4s*2 - 295312500p*6qs3 - 2938906250p*3q*3s*3 - 4848750000q*5s*3 + 3791484375p*4qrs*3 + 7556250000pq3rs3 - 11960937500p*2qr2s*3 - 9375000000qr3s*3 + 1668515625p*5s*4 + 20447265625p*2q*2s*4 - 21955078125p*3rs4 + 18984375000q*2rs4 + 67382812500pr2s*4 - 120849609375pqs*5 + 157226562500s*6 return o @property def a(self): p, q, r, s = self.p, self.q, self.r, self.s a = [0]6 a[5] = -100p7q*7 - 2175p*4q*9 - 10500pq11 + 1100p*8q*5r + 27975p5q*7r + 152950p2q*9r - 4125p9q*3r*2 - 128875p*6q*5r*2 - 830525p*3q*7r*2 + 59450q*9r*2 + 5400p*10qr3 + 243800p*7q*3r*3 + 2082650p*4q*5r*3 - 333925pq7r*3 - 139200p*8qr4 - 2406000p*5q*3r*4 - 122600p*2q*5r*4 + 1254400p*6qr5 + 3776000p*3q*3r*5 + 1832000q*5r*5 - 4736000p*4qr6 - 6720000pq3r*6 + 6400000p*2qr7 - 900p*9q*4s - 37400p6q*6s - 281625p3q*8s - 435000q10s + 6750p10q*2rs + 322300p*7q*4rs + 2718575p*4q*6rs + 4214250pq8rs - 16200p*11r*2s - 859275p8q*2r*2s - 8925475p5q*4r*2s - 14427875p2q*6r*2s + 453600p9r*3s + 10038400p6q*2r*3s + 17397500p3q*4r*3s - 11333125q6r*3s - 4451200p7r*4s - 15850000p4q*2r*4s + 34000000pq*4r*4s + 17984000p5r*5s - 10000000p2q*2r*5s - 25600000p3r*6s - 8000000q2r*6s + 6075p11qs2 - 83250p*8q*3s*2 - 1282500p*5q*5s*2 - 2862500p*2q*7s*2 + 724275p*9qrs*2 + 9807250p*6q*3rs2 + 28374375p*3q*5rs2 + 22212500q*7rs2 - 8982000p*7qr2s*2 - 39600000p*4q*3r*2s*2 - 61746875pq5r*2s*2 - 1010000p*5qr3s*2 - 1000000p*2q*3r*3s*2 + 78000000p*3qr4s*2 + 30000000q*3r*4s*2 + 80000000pqr*5s*2 - 759375p*10s*3 - 9787500p*7q*2s*3 - 39062500p*4q*4s*3 - 52343750pq6s*3 + 12301875p*8rs3 + 98175000p*5q*2rs3 + 225078125p*2q*4rs3 - 54900000p*6r*2s*3 - 310000000p*3q*2r*2s*3 - 7890625q*4r*2s*3 + 51250000p*4r*3s*3 - 420000000pq2r*3s*3 + 110000000p*2r*4s*3 - 200000000r*5s*3 + 2109375p*6qs4 - 21093750p*3q*3s*4 - 89843750q*5s*4 + 182343750p*4qrs*4 + 733203125pq3rs4 - 196875000p*2qr2s*4 + 1125000000qr3s*4 - 158203125p*5s*5 - 566406250p*2q*2s*5 + 101562500p*3rs5 - 1669921875q*2rs5 + 1250000000pr2s*5 - 1220703125pqs*6 + 6103515625s*7 a[4] = 1000p*5q*7 + 7250p*2q*9 - 10800p*6q*5r - 96900p3q*7r - 52500q9r + 37400p7q*3r*2 + 470850p*4q*5r*2 + 640600pq7r*2 - 39600p*8qr3 - 983600p*5q*3r*3 - 2848100p*2q*5r*3 + 814400p*6qr4 + 6076000p*3q*3r*4 + 2308000q*5r*4 - 5024000p*4qr5 - 9680000pq3r*5 + 9600000p*2qr6 + 13800p*7q*4s + 94650p4q*6s - 26500pq*8s - 86400p8q*2rs - 816500p*5q*4rs - 257500p*2q*6rs + 91800p*9r*2s + 1853700p6q*2r*2s + 630000p3q*4r*2s - 8971250q6r*2s - 2071200p7r*3s - 7240000p4q*2r*3s + 29375000pq*4r*3s + 14416000p5r*4s - 5200000p2q*2r*4s - 30400000p3r*5s - 12000000q2r*5s + 64800p9qs2 + 567000p*6q*3s*2 + 1655000p*3q*5s*2 + 6987500q*7s*2 + 337500p*7qrs*2 + 8462500p*4q*3rs2 - 5812500pq5rs2 - 24930000p*5qr2s*2 - 69125000p*2q*3r*2s*2 + 103500000p*3qr3s*2 + 30000000q*3r*3s*2 + 90000000pqr*4s*2 - 708750p*8s*3 - 5400000p*5q*2s*3 + 8906250p*2q*4s*3 + 18562500p*6rs3 - 625000p*3q*2rs3 + 29687500q*4rs3 - 75000000p*4r*2s*3 - 416250000pq2r*2s*3 + 60000000p*2r*3s*3 - 300000000r*4s*3 + 71718750p*4qs4 + 189062500pq3s*4 + 210937500p*2qrs*4 + 1187500000qr2s*4 - 187500000p*3s*5 - 800781250q*2s*5 - 390625000prs*5 a[3] = -500p*6q*5 - 6350p*3q*7 - 19800q*9 + 3750p*7q*3r + 65100p4q*5r + 264950pq*7r - 6750p8qr2 - 209050p*5q*3r*2 - 1217250p*2q*5r*2 + 219000p*6qr3 + 2510000p*3q*3r*3 + 1098500q*5r*3 - 2068000p*4qr4 - 5060000pq3r*4 + 5200000p*2qr5 - 6750p*8q*2s - 96350p5q*4s - 346000p2q*6s + 20250p9rs + 459900p*6q*2rs + 1828750p*3q*4rs - 2930000q*6rs - 594000p*7r*2s - 4301250p4q*2r*2s + 10906250pq*4r*2s + 5252000p5r*3s - 1450000p2q*2r*3s - 12800000p3r*4s - 6500000q2r*4s + 74250p7qs2 + 1418750p*4q*3s*2 + 5956250pq5s*2 - 4297500p*5qrs*2 - 29906250p*2q*3rs2 + 31500000p*3qr2s*2 + 12500000q*3r*2s*2 + 35000000pqr*3s*2 + 1350000p*6s*3 + 6093750p*3q*2s*3 + 17500000q*4s*3 - 7031250p*4rs3 - 127812500pq2rs3 + 18750000p*2r*2s*3 - 162500000r*3s*3 + 107812500p*2qs4 + 460937500qrs*4 - 214843750ps5 a[2] = 1950p*4q*5 + 14100pq7 - 14350p*5q*3r - 125600p2q*5r + 27900p6qr2 + 402250p*3q*3r*2 + 288250q*5r*2 - 436000p*4qr3 - 1345000pq3r*3 + 1400000p*2qr4 + 9450p*6q*2s - 1250p3q*4s - 465000q6s - 49950p7rs - 302500p*4q*2rs + 1718750pq4rs + 834000p*5r*2s + 437500p2q*2r*2s - 3100000p3r*3s - 1750000q2r*3s - 292500p5qs2 - 1937500p*2q*3s*2 + 3343750p*3qrs*2 + 1875000q*3rs2 + 8125000pqr*2s*2 - 1406250p*4s*3 - 12343750pq2s*3 + 5312500p*2rs3 - 43750000r*2s*3 + 74218750qs4 a[1] = -300p*5q*3 - 2150p*2q*5 + 1350p*6qr + 21500p*3q*3r + 61500q5r - 42000p4qr2 - 290000pq3r*2 + 300000p*2qr3 - 4050p*7s - 45000p4q*2s - 125000pq*4s + 108000p5rs + 643750p*2q*2rs - 700000p*3r*2s - 375000q2r*2s - 93750p3qs2 - 312500q*3s*2 + 1875000pqrs2 - 1406250p*2s*3 - 9375000rs3 a[0] = 1250p*3q*3 + 9000q*5 - 4500p*4qr - 46250pq3r + 50000p2qr2 + 6750p*5s + 43750p2q*2s - 75000p3rs - 62500q*2rs + 156250pqs*2 - 1562500s*3 return a @property def c(self): p, q, r, s = self.p, self.q, self.r, self.s c = [0]6 c[5] = -40p5q*11 - 270p*2q*13 + 700p*6q*9r + 5165p3q*11r + 540q13r - 4230p7q*7r*2 - 31845p*4q*9r*2 + 20880pq11r*2 + 9645p*8q*5r*3 + 57615p*5q*7r*3 - 358255p*2q*9r*3 - 1880p*9q*3r*4 + 114020p*6q*5r*4 + 2012190p*3q*7r*4 - 26855q*9r*4 - 14400p*10qr5 - 470400p*7q*3r*5 - 5088640p*4q*5r*5 + 920pq7r*5 + 332800p*8qr6 + 5797120p*5q*3r*6 + 1608000p*2q*5r*6 - 2611200p*6qr7 - 7424000p*3q*3r*7 - 2323200q*5r*7 + 8601600p*4qr8 + 9472000pq3r*8 - 10240000p*2qr9 - 3060p*7q*8s - 39085p4q*10s - 132300pq*12s + 36580p8q*6rs + 520185p*5q*8rs + 1969860p*2q*10rs - 144045p*9q*4r*2s - 2438425p6q*6r*2s - 10809475p3q*8r*2s + 518850q10r*2s + 182520p10q*2r*3s + 4533930p7q*4r*3s + 26196770p4q*6r*3s - 4542325pq*8r*3s + 21600p11r*4s - 2208080p8q*2r*4s - 24787960p5q*4r*4s + 10813900p2q*6r*4s - 499200p9r*5s + 3827840p6q*2r*5s + 9596000p3q*4r*5s + 22662000q6r*5s + 3916800p7r*6s - 29952000p4q*2r*6s - 90800000pq*4r*6s - 12902400p5r*7s + 87040000p2q*2r*7s + 15360000p3r*8s + 12800000q2r*8s - 38070p9q*5s*2 - 566700p*6q*7s*2 - 2574375p*3q*9s*2 - 1822500q*11s*2 + 292815p*10q*3rs2 + 5170280p*7q*5rs2 + 27918125p*4q*7rs2 + 21997500pq9rs2 - 573480p*11qr2s*2 - 14566350p*8q*3r*2s*2 - 104851575p*5q*5r*2s*2 - 96448750p*2q*7r*2s*2 + 11001240p*9qr3s*2 + 147798600p*6q*3r*3s*2 + 158632750p*3q*5r*3s*2 - 78222500q*7r*3s*2 - 62819200p*7qr4s*2 - 136160000p*4q*3r*4s*2 + 317555000pq5r*4s*2 + 160224000p*5qr5s*2 - 267600000p*2q*3r*5s*2 - 153600000p*3qr6s*2 - 120000000q*3r*6s*2 - 32000000pqr*7s*2 - 127575p*11q*2s*3 - 2148750p*8q*4s*3 - 13652500p*5q*6s*3 - 19531250p*2q*8s*3 + 495720p*12rs3 + 11856375p*9q*2rs3 + 107807500p*6q*4rs3 + 222334375p*3q*6rs3 + 105062500q*8rs3 - 11566800p*10r*2s*3 - 216787500p*7q*2r*2s*3 - 633437500p*4q*4r*2s*3 - 504484375pq6r*2s*3 + 90918000p*8r*3s*3 + 567080000p*5q*2r*3s*3 + 692937500p*2q*4r*3s*3 - 326640000p*6r*4s*3 - 339000000p*3q*2r*4s*3 + 369250000q*4r*4s*3 + 560000000p*4r*5s*3 + 508000000pq2r*5s*3 - 480000000p*2r*6s*3 + 320000000r*7s*3 - 455625p*10qs4 - 27562500p*7q*3s*4 - 120593750p*4q*5s*4 - 60312500pq7s*4 + 110615625p*8qrs*4 + 662984375p*5q*3rs4 + 528515625p*2q*5rs4 - 541687500p*6qr2s*4 - 1262343750p*3q*3r*2s*4 - 466406250q*5r*2s*4 + 633000000p*4qr3s*4 - 1264375000pq3r*3s*4 + 1085000000p*2qr4s*4 - 2700000000qr5s*4 - 68343750p*9s*5 - 478828125p*6q*2s*5 - 355468750p*3q*4s*5 - 11718750q*6s*5 + 718031250p*7rs5 + 1658593750p*4q*2rs5 + 2212890625pq4rs5 - 2855625000p*5r*2s*5 - 4273437500p*2q*2r*2s*5 + 4537500000p*3r*3s*5 + 8031250000q*2r*3s*5 - 1750000000pr4s*5 + 1353515625p*5qs6 + 1562500000p*2q*3s*6 - 3964843750p*3qrs*6 - 7226562500q*3rs6 + 1953125000pqr*2s*6 - 1757812500p*4s*7 - 3173828125pq2s*7 + 6445312500p*2rs7 - 3906250000r*2s*7 + 6103515625qs8 c[4] = 40p*6q*9 + 110p*3q*11 - 1080q*13 - 560p*7q*7r - 1780p4q*9r + 17370pq*11r + 2850p8q*5r*2 + 10520p*5q*7r*2 - 115910p*2q*9r*2 - 6090p*9q*3r*3 - 25330p*6q*5r*3 + 448740p*3q*7r*3 + 128230q*9r*3 + 4320p*10qr4 + 16960p*7q*3r*4 - 1143600p*4q*5r*4 - 1410310pq7r*4 + 3840p*8qr5 + 1744480p*5q*3r*5 + 5619520p*2q*5r*5 - 1198080p*6qr6 - 10579200p*3q*3r*6 - 2940800q*5r*6 + 8294400p*4qr7 + 13568000pq3r*7 - 15360000p*2qr8 + 840p*8q*6s + 7580p5q*8s + 24420p2q*10s - 8100p9q*4rs - 94100p*6q*6rs - 473000p*3q*8rs - 473400q*10rs + 22680p*10q*2r*2s + 374370p7q*4r*2s + 2888020p4q*6r*2s + 5561050pq*8r*2s - 12960p11r*3s - 485820p8q*2r*3s - 6723440p5q*4r*3s - 23561400p2q*6r*3s + 190080p9r*4s + 5894880p6q*2r*4s + 50882000p3q*4r*4s + 22411500q6r*4s - 258560p7r*5s - 46248000p4q*2r*5s - 103800000pq*4r*5s - 3737600p5r*6s + 119680000p2q*2r*6s + 10240000p3r*7s + 19200000q2r*7s + 7290p10q*3s*2 + 117360p*7q*5s*2 + 691250p*4q*7s*2 - 198750pq9s*2 - 36450p*11qrs*2 - 854550p*8q*3rs2 - 7340700p*5q*5rs2 - 2028750p*2q*7rs2 + 995490p*9qr2s*2 + 18896600p*6q*3r*2s*2 + 5026500p*3q*5r*2s*2 - 52272500q*7r*2s*2 - 16636800p*7qr3s*2 - 43200000p*4q*3r*3s*2 + 223426250pq5r*3s*2 + 112068000p*5qr4s*2 - 177000000p*2q*3r*4s*2 - 244000000p*3qr5s*2 - 156000000q*3r*5s*2 + 43740p*12s*3 + 1032750p*9q*2s*3 + 8602500p*6q*4s*3 + 15606250p*3q*6s*3 + 39625000q*8s*3 - 1603800p*10rs3 - 26932500p*7q*2rs3 - 19562500p*4q*4rs3 - 152000000pq6rs3 + 25555500p*8r*2s*3 + 16230000p*5q*2r*2s*3 + 42187500p*2q*4r*2s*3 - 165660000p*6r*3s*3 + 373500000p*3q*2r*3s*3 + 332937500q*4r*3s*3 + 465000000p*4r*4s*3 + 586000000pq2r*4s*3 - 592000000p*2r*5s*3 + 480000000r*6s*3 - 1518750p*8qs4 - 62531250p*5q*3s*4 + 7656250p*2q*5s*4 + 184781250p*6qrs*4 - 15781250p*3q*3rs4 - 135156250q*5rs4 - 1148250000p*4qr2s*4 - 2121406250pq3r*2s*4 + 1990000000p*2qr3s*4 - 3150000000qr4s*4 - 2531250p*7s*5 + 660937500p*4q*2s*5 + 1339843750pq4s*5 - 33750000p*5rs5 - 679687500p*2q*2rs5 + 6250000p*3r*2s*5 + 6195312500q*2r*2s*5 + 1125000000pr3s*5 - 996093750p*3qs6 - 3125000000q*3s*6 - 3222656250pqrs6 + 1171875000p*2s*7 + 976562500rs7 c[3] = 80p*4q*9 + 540pq11 - 600p*5q*7r - 4770p2q*9r + 1230p6q*5r*2 + 20900p*3q*7r*2 + 47250q*9r*2 - 710p*7q*3r*3 - 84950p*4q*5r*3 - 526310pq7r*3 + 720p*8qr4 + 216280p*5q*3r*4 + 2068020p*2q*5r*4 - 198080p*6qr5 - 3703200p*3q*3r*5 - 1423600q*5r*5 + 2860800p*4qr6 + 7056000pq3r*6 - 8320000p*2qr7 - 2720p*6q*6s - 46350p3q*8s - 178200q10s + 25740p7q*4rs + 489490p*4q*6rs + 2152350pq8rs - 61560p*8q*2r*2s - 1568150p5q*4r*2s - 9060500p2q*6r*2s + 24840p9r*3s + 1692380p6q*2r*3s + 18098250p3q*4r*3s + 9387750q6r*3s - 382560p7r*4s - 16818000p4q*2r*4s - 49325000pq*4r*4s + 1212800p5r*5s + 64840000p2q*2r*5s - 320000p3r*6s + 10400000q2r*6s - 36450p8q*3s*2 - 588350p*5q*5s*2 - 2156250p*2q*7s*2 + 123930p*9qrs*2 + 2879700p*6q*3rs2 + 12548000p*3q*5rs2 - 14445000q*7rs2 - 3233250p*7qr2s*2 - 28485000p*4q*3r*2s*2 + 72231250pq5r*2s*2 + 32093000p*5qr3s*2 - 61275000p*2q*3r*3s*2 - 107500000p*3qr4s*2 - 78500000q*3r*4s*2 + 22000000pqr*5s*2 - 72900p*10s*3 - 1215000p*7q*2s*3 - 2937500p*4q*4s*3 + 9156250pq6s*3 + 2612250p*8rs3 + 16560000p*5q*2rs3 - 75468750p*2q*4rs3 - 32737500p*6r*2s*3 + 169062500p*3q*2r*2s*3 + 121718750q*4r*2s*3 + 160250000p*4r*3s*3 + 219750000pq2r*3s*3 - 317000000p*2r*4s*3 + 260000000r*5s*3 + 2531250p*6qs4 + 22500000p*3q*3s*4 + 39843750q*5s*4 - 266343750p*4qrs*4 - 776406250pq3rs4 + 789062500p*2qr2s*4 - 1368750000qr3s*4 + 67500000p*5s*5 + 441406250p*2q*2s*5 - 311718750p*3rs5 + 1785156250q*2rs5 + 546875000pr2s*5 - 1269531250pqs*6 + 488281250s*7 c[2] = 120p*5q*7 + 810p*2q*9 - 1280p*6q*5r - 9160p3q*7r + 3780q9r + 4530p7q*3r*2 + 36640p*4q*5r*2 - 45270pq7r*2 - 5400p*8qr3 - 60920p*5q*3r*3 + 200050p*2q*5r*3 + 31200p*6qr4 - 476000p*3q*3r*4 - 378200q*5r*4 + 521600p*4qr5 + 1872000pq3r*5 - 2240000p*2qr6 + 1440p*7q*4s + 15310p4q*6s + 59400pq*8s - 9180p8q*2rs - 115240p*5q*4rs - 589650p*2q*6rs + 16200p*9r*2s + 316710p6q*2r*2s + 2547750p3q*4r*2s + 2178000q6r*2s - 259200p7r*3s - 4123000p4q*2r*3s - 11700000pq*4r*3s + 937600p5r*4s + 16340000p2q*2r*4s - 640000p3r*5s + 2800000q2r*5s - 2430p9qs2 - 54450p*6q*3s*2 - 285500p*3q*5s*2 - 2767500q*7s*2 + 43200p*7qrs*2 - 916250p*4q*3rs2 + 14482500pq5rs2 + 4806000p*5qr2s*2 - 13212500p*2q*3r*2s*2 - 25400000p*3qr3s*2 - 18750000q*3r*3s*2 + 8000000pqr*4s*2 + 121500p*8s*3 + 2058750p*5q*2s*3 - 6656250p*2q*4s*3 - 6716250p*6rs3 + 24125000p*3q*2rs3 + 23875000q*4rs3 + 43125000p*4r*2s*3 + 45750000pq2r*2s*3 - 87500000p*2r*3s*3 + 70000000r*4s*3 - 44437500p*4qs4 - 107968750pq3s*4 + 159531250p*2qrs*4 - 284375000qr2s*4 + 7031250p*3s*5 + 265625000q*2s*5 + 31250000prs*5 c[1] = 160p*3q*7 + 1080q*9 - 1080p*4q*5r - 8730pq*7r + 1510p5q*3r*2 + 20420p*2q*5r*2 + 720p*6qr3 - 23200p*3q*3r*3 - 79900q*5r*3 + 35200p*4qr4 + 404000pq3r*4 - 480000p*2qr5 + 960p*5q*4s + 2850p2q*6s + 540p6q*2rs + 63500p*3q*4rs + 319500q*6rs - 7560p*7r*2s - 253500p4q*2r*2s - 1806250pq*4r*2s + 91200p5r*3s + 2600000p2q*2r*3s - 80000p3r*4s + 600000q2r*4s - 4050p7qs2 - 120000p*4q*3s*2 - 273750pq5s*2 + 425250p*5qrs*2 + 2325000p*2q*3rs2 - 5400000p*3qr2s*2 - 2875000q*3r*2s*2 + 1500000pqr*3s*2 - 303750p*6s*3 - 843750p*3q*2s*3 - 812500q*4s*3 + 5062500p*4rs3 + 13312500pq2rs3 - 14500000p*2r*2s*3 + 15000000r*3s*3 - 3750000p*2qs4 - 35937500qrs*4 + 11718750ps5 c[0] = 80p*4q*5 + 540pq7 - 600p*5q*3r - 4770p2q*5r + 1080p6qr2 + 11200p*3q*3r*2 - 12150q*5r*2 - 4800p*4qr3 + 64000pq3r*3 - 80000p*2qr4 + 1080p*6q*2s + 13250p3q*4s + 54000q6s - 3240p7rs - 56250p*4q*2rs - 337500pq4rs + 43200p*5r*2s + 560000p2q*2r*2s - 80000p3r*3s + 100000q2r*3s + 6750p5qs2 + 225000p*2q*3s*2 - 900000p*3qrs*2 - 562500q*3rs2 + 500000pqr*2s*2 + 843750p*4s*3 + 1937500pq2s*3 - 3000000p*2rs3 + 2500000r*2s*3 - 5468750qs4 return c @property def F(self): p, q, r, s = self.p, self.q, self.r, self.s F = 4p*6q*6 + 59p*3q*8 + 216q*10 - 36p*7q*4r - 623p4q*6r - 2610pq*8r + 81p8q*2r*2 + 2015p*5q*4r*2 + 10825p*2q*6r*2 - 1800p*6q*2r*3 - 17500p*3q*4r*3 + 625q*6r*3 + 10000p*4q*2r*4 + 108p*8q*3s + 1584p5q*5s + 5700p2q*7s - 486p9qrs - 9720p6q*3rs - 45050p*3q*5rs - 9000q*7rs + 10800p*7qr2s + 92500p4q*3r*2s + 32500pq*5r*2s - 60000p5qr3s - 50000p2q*3r*3s + 729p10s*2 + 12150p*7q*2s*2 + 60000p*4q*4s*2 + 93750pq6s*2 - 18225p*8rs2 - 175500p*5q*2rs2 - 478125p*2q*4rs2 + 135000p*6r*2s*2 + 850000p*3q*2r*2s*2 + 15625q*4r*2s*2 - 250000p*4r*3s*2 + 225000p*3q*3s*3 + 175000q*5s*3 - 1012500p*4qrs*3 - 1187500pq3rs3 + 1250000p*2qr2s*3 + 928125p*5s*4 + 1875000p*2q*2s*4 - 2812500p*3rs4 - 390625q*2rs4 - 9765625s*6 return F def l0(self, theta): F = self.F a = self.a l0 = Poly(a, x).eval(theta)/F return l0 def T(self, theta, d): F = self.F T = [0]5 b = self.b # Note that the order of sublists of the b's has been reversed compared to the paper T[1] = -Poly(b[1], x).eval(theta)/(2F) T[2] = Poly(b[2], x).eval(theta)/(2dF) T[3] = Poly(b[3], x).eval(theta)/(2F) T[4] = Poly(b[4], x).eval(theta)/(2dF) return T def order(self, theta, d): F = self.F o = self.o order = Poly(o, x).eval(theta)/(dF) return N(order) def uv(self, theta, d): c = self.c u = S(-25self.q/2) v = Poly(c, x).eval(theta)/(2dself.F) return N(u), N(v) @property def zeta(self): return [self.zeta1, self.zeta2, self.zeta3, self.zeta4]
760bf2545b5f156792d1b10aef5b5a85cc07e8157ec7ee212c09df493302cd15	"""Implementation of RootOf class and related tools. """ from __future__ import print_function, division from sympy.core import (S, Expr, Integer, Float, I, oo, Add, Lambda, symbols, sympify, Rational, Dummy) from sympy.core.cache import cacheit from sympy.core.compatibility import range, ordered from sympy.core.function import AppliedUndef from sympy.polys.domains import QQ from sympy.polys.polyerrors import ( MultivariatePolynomialError, GeneratorsNeeded, PolynomialError, DomainError) from sympy.polys.polyfuncs import symmetrize, viete from sympy.polys.polyroots import ( roots_linear, roots_quadratic, roots_binomial, preprocess_roots, roots) from sympy.polys.polytools import Poly, PurePoly, factor from sympy.polys.rationaltools import together from sympy.polys.rootisolation import ( dup_isolate_complex_roots_sqf, dup_isolate_real_roots_sqf) from sympy.utilities import lambdify, public, sift from mpmath import mpf, mpc, findroot, workprec from mpmath.libmp.libmpf import dps_to_prec, prec_to_dps __all__ = ['CRootOf'] class _pure_key_dict(object): """A minimal dictionary that makes sure that the key is a univariate PurePoly instance. Examples ======== Only the following actions are guaranteed: >>> from sympy.polys.rootoftools import _pure_key_dict >>> from sympy import S, PurePoly >>> from sympy.abc import x, y 1) creation >>> P = _pure_key_dict() 2) assignment for a PurePoly or univariate polynomial >>> P[x] = 1 >>> P[PurePoly(x - y, x)] = 2 3) retrieval based on PurePoly key comparison (use this instead of the get method) >>> P[y] 1 4) KeyError when trying to retrieve a nonexisting key >>> P[y + 1] Traceback (most recent call last): ... KeyError: PurePoly(y + 1, y, domain='ZZ') 5) ability to query with ``in`` >>> x + 1 in P False NOTE: this is a not a dictionary. It is a very basic object for internal use that makes sure to always address its cache via PurePoly instances. It does not, for example, implement ``get`` or ``setdefault``. """ def __init__(self): self._dict = {} def __getitem__(self, k): if not isinstance(k, PurePoly): if not (isinstance(k, Expr) and len(k.free_symbols) == 1): raise KeyError k = PurePoly(k, expand=False) return self._dict[k] def __setitem__(self, k, v): if not isinstance(k, PurePoly): if not (isinstance(k, Expr) and len(k.free_symbols) == 1): raise ValueError('expecting univariate expression') k = PurePoly(k, expand=False) self._dict[k] = v def __contains__(self, k): try: self[k] return True except KeyError: return False _reals_cache = _pure_key_dict() _complexes_cache = _pure_key_dict() def _pure_factors(poly): _, factors = poly.factor_list() return [(PurePoly(f, expand=False), m) for f, m in factors] def _imag_count_of_factor(f): """Return the number of imaginary roots for irreducible univariate polynomial ``f``. """ terms = [(i, j) for (i,), j in f.terms()] if any(i % 2 for i, j in terms): return 0 # update signs even = [(i, I*ij) for i, j in terms] even = Poly.from_dict(dict(even), Dummy('x')) return int(even.count_roots(-oo, oo)) @public def rootof(f, x, index=None, radicals=True, expand=True): """An indexed root of a univariate polynomial. Returns either a ``ComplexRootOf`` object or an explicit expression involving radicals. Parameters ========== f : Expr Univariate polynomial. x : Symbol, optional Generator for ``f``. index : int or Integer radicals : bool Return a radical expression if possible. expand : bool Expand ``f``. """ return CRootOf(f, x, index=index, radicals=radicals, expand=expand) @public class RootOf(Expr): """Represents a root of a univariate polynomial. Base class for roots of different kinds of polynomials. Only complex roots are currently supported. """ __slots__ = ['poly'] def __new__(cls, f, x, index=None, radicals=True, expand=True): """Construct a new ``CRootOf`` object for ``k``-th root of ``f``.""" return rootof(f, x, index=index, radicals=radicals, expand=expand) @public class ComplexRootOf(RootOf): """Represents an indexed complex root of a polynomial. Roots of a univariate polynomial separated into disjoint real or complex intervals and indexed in a fixed order. Currently only rational coefficients are allowed. Can be imported as ``CRootOf``. To avoid confusion, the generator must be a Symbol. Examples ======== >>> from sympy import CRootOf, rootof >>> from sympy.abc import x CRootOf is a way to reference a particular root of a polynomial. If there is a rational root, it will be returned: >>> CRootOf.clear_cache() # for doctest reproducibility >>> CRootOf(x2 - 4, 0) -2 Whether roots involving radicals are returned or not depends on whether the ``radicals`` flag is true (which is set to True with rootof): >>> CRootOf(x2 - 3, 0) CRootOf(x2 - 3, 0) >>> CRootOf(x2 - 3, 0, radicals=True) -sqrt(3) >>> rootof(x*2 - 3, 0) -sqrt(3) The following cannot be expressed in terms of radicals: >>> r = rootof(4x*5 + 16x*3 + 12x*2 + 7, 0); r CRootOf(4x*5 + 16x*3 + 12x2 + 7, 0) The root bounds can be seen, however, and they are used by the evaluation methods to get numerical approximations for the root. >>> interval = r._get_interval(); interval (-1, 0) >>> r.evalf(2) -0.98 The evalf method refines the width of the root bounds until it guarantees that any decimal approximation within those bounds will satisfy the desired precision. It then stores the refined interval so subsequent requests at or below the requested precision will not have to recompute the root bounds and will return very quickly. Before evaluation above, the interval was >>> interval (-1, 0) After evaluation it is now >>. r._get_interval() (-165/169, -206/211) To reset all intervals for a given polynomial, the `_reset` method can be called from any CRootOf instance of the polynomial: >>> r._reset() >>> r._get_interval() (-1, 0) The `eval_approx` method will also find the root to a given precision but the interval is not modified unless the search for the root fails to converge within the root bounds. And the secant method is used to find the root. (The ``evalf`` method uses bisection and will always update the interval.) >>> r.eval_approx(2) -0.98 The interval needed to be slightly updated to find that root: >>> r._get_interval() (-1, -1/2) The ``evalf_rational`` will compute a rational approximation of the root to the desired accuracy or precision. >>> r.eval_rational(n=2) -69629/71318 >>> t = CRootOf(x3 + 10x + 1, 1) >>> t.eval_rational(1e-1) 15/256 - 805I/256 >>> t.eval_rational(1e-1, 1e-4) 3275/65536 - 414645I/131072 >>> t.eval_rational(1e-4, 1e-4) 6545/131072 - 414645I/131072 >>> t.eval_rational(n=2) 104755/2097152 - 6634255I/2097152 Notes ===== Although a PurePoly can be constructed from a non-symbol generator RootOf instances of non-symbols are disallowed to avoid confusion over what root is being represented. >>> from sympy import exp, PurePoly >>> PurePoly(x) == PurePoly(exp(x)) True >>> CRootOf(x - 1, 0) 1 >>> CRootOf(exp(x) - 1, 0) # would correspond to x == 0 Traceback (most recent call last): ... sympy.polys.polyerrors.PolynomialError: generator must be a Symbol See Also ======== eval_approx eval_rational _eval_evalf """ __slots__ = ['index'] is_complex = True is_number = True def __new__(cls, f, x, index=None, radicals=False, expand=True): """ Construct an indexed complex root of a polynomial. See ``rootof`` for the parameters. The default value of ``radicals`` is ``False`` to satisfy ``eval(srepr(expr) == expr``. """ x = sympify(x) if index is None and x.is_Integer: x, index = None, x else: index = sympify(index) if index is not None and index.is_Integer: index = int(index) else: raise ValueError("expected an integer root index, got %s" % index) poly = PurePoly(f, x, greedy=False, expand=expand) if not poly.is_univariate: raise PolynomialError("only univariate polynomials are allowed") if not poly.gen.is_Symbol: # PurePoly(sin(x) + 1) == PurePoly(x + 1) but the roots of # x for each are not the same: issue 8617 raise PolynomialError("generator must be a Symbol") degree = poly.degree() if degree <= 0: raise PolynomialError("can't construct CRootOf object for %s" % f) if index < -degree or index >= degree: raise IndexError("root index out of [%d, %d] range, got %d" % (-degree, degree - 1, index)) elif index < 0: index += degree dom = poly.get_domain() if not dom.is_Exact: poly = poly.to_exact() roots = cls._roots_trivial(poly, radicals) if roots is not None: return roots[index] coeff, poly = preprocess_roots(poly) dom = poly.get_domain() if not dom.is_ZZ: raise NotImplementedError("CRootOf is not supported over %s" % dom) root = cls._indexed_root(poly, index) return coeff cls._postprocess_root(root, radicals) @classmethod def _new(cls, poly, index): """Construct new ``CRootOf`` object from raw data. """ obj = Expr.__new__(cls) obj.poly = PurePoly(poly) obj.index = index try: _reals_cache[obj.poly] = _reals_cache[poly] _complexes_cache[obj.poly] = _complexes_cache[poly] except KeyError: pass return obj def _hashable_content(self): return (self.poly, self.index) @property def expr(self): return self.poly.as_expr() @property def args(self): return (self.expr, Integer(self.index)) @property def free_symbols(self): # CRootOf currently only works with univariate expressions # whose poly attribute should be a PurePoly with no free # symbols return set() def _eval_is_real(self): """Return ``True`` if the root is real. """ return self.index < len(_reals_cache[self.poly]) def _eval_is_imaginary(self): """Return ``True`` if the root is imaginary. """ if self.index >= len(_reals_cache[self.poly]): ivl = self._get_interval() return ivl.axivl.bx <= 0 # all others are on one side or the other return False # XXX is this necessary? @classmethod def real_roots(cls, poly, radicals=True): """Get real roots of a polynomial. """ return cls._get_roots("_real_roots", poly, radicals) @classmethod def all_roots(cls, poly, radicals=True): """Get real and complex roots of a polynomial. """ return cls._get_roots("_all_roots", poly, radicals) @classmethod def _get_reals_sqf(cls, currentfactor, use_cache=True): """Get real root isolating intervals for a square-free factor.""" if use_cache and currentfactor in _reals_cache: real_part = _reals_cache[currentfactor] else: _reals_cache[currentfactor] = real_part = \ dup_isolate_real_roots_sqf( currentfactor.rep.rep, currentfactor.rep.dom, blackbox=True) return real_part @classmethod def _get_complexes_sqf(cls, currentfactor, use_cache=True): """Get complex root isolating intervals for a square-free factor.""" if use_cache and currentfactor in _complexes_cache: complex_part = _complexes_cache[currentfactor] else: _complexes_cache[currentfactor] = complex_part = \ dup_isolate_complex_roots_sqf( currentfactor.rep.rep, currentfactor.rep.dom, blackbox=True) return complex_part @classmethod def _get_reals(cls, factors, use_cache=True): """Compute real root isolating intervals for a list of factors. """ reals = [] for currentfactor, k in factors: try: if not use_cache: raise KeyError r = _reals_cache[currentfactor] reals.extend([(i, currentfactor, k) for i in r]) except KeyError: real_part = cls._get_reals_sqf(currentfactor, use_cache) new = [(root, currentfactor, k) for root in real_part] reals.extend(new) reals = cls._reals_sorted(reals) return reals @classmethod def _get_complexes(cls, factors, use_cache=True): """Compute complex root isolating intervals for a list of factors. """ complexes = [] for currentfactor, k in ordered(factors): try: if not use_cache: raise KeyError c = _complexes_cache[currentfactor] complexes.extend([(i, currentfactor, k) for i in c]) except KeyError: complex_part = cls._get_complexes_sqf(currentfactor, use_cache) new = [(root, currentfactor, k) for root in complex_part] complexes.extend(new) complexes = cls._complexes_sorted(complexes) return complexes @classmethod def _reals_sorted(cls, reals): """Make real isolating intervals disjoint and sort roots. """ cache = {} for i, (u, f, k) in enumerate(reals): for j, (v, g, m) in enumerate(reals[i + 1:]): u, v = u.refine_disjoint(v) reals[i + j + 1] = (v, g, m) reals[i] = (u, f, k) reals = sorted(reals, key=lambda r: r[0].a) for root, currentfactor, _ in reals: if currentfactor in cache: cache[currentfactor].append(root) else: cache[currentfactor] = [root] for currentfactor, root in cache.items(): _reals_cache[currentfactor] = root return reals @classmethod def _refine_imaginary(cls, complexes): sifted = sift(complexes, lambda c: c[1]) complexes = [] for f in ordered(sifted): nimag = _imag_count_of_factor(f) if nimag == 0: # refine until xbounds are neg or pos for u, f, k in sifted[f]: while u.axu.bx <= 0: u = u._inner_refine() complexes.append((u, f, k)) else: # refine until all but nimag xbounds are neg or pos potential_imag = list(range(len(sifted[f]))) while True: assert len(potential_imag) > 1 for i in list(potential_imag): u, f, k = sifted[f][i] if u.axu.bx > 0: potential_imag.remove(i) elif u.ax != u.bx: u = u._inner_refine() sifted[f][i] = u, f, k if len(potential_imag) == nimag: break complexes.extend(sifted[f]) return complexes @classmethod def _refine_complexes(cls, complexes): """return complexes such that no bounding rectangles of non-conjugate roots would intersect. In addition, assure that neither ay nor by is 0 to guarantee that non-real roots are distinct from real roots in terms of the y-bounds. """ # get the intervals pairwise-disjoint. # If rectangles were drawn around the coordinates of the bounding # rectangles, no rectangles would intersect after this procedure. for i, (u, f, k) in enumerate(complexes): for j, (v, g, m) in enumerate(complexes[i + 1:]): u, v = u.refine_disjoint(v) complexes[i + j + 1] = (v, g, m) complexes[i] = (u, f, k) # refine until the x-bounds are unambiguously positive or negative # for non-imaginary roots complexes = cls._refine_imaginary(complexes) # make sure that all y bounds are off the real axis # and on the same side of the axis for i, (u, f, k) in enumerate(complexes): while u.ayu.by <= 0: u = u.refine() complexes[i] = u, f, k return complexes @classmethod def _complexes_sorted(cls, complexes): """Make complex isolating intervals disjoint and sort roots. """ complexes = cls._refine_complexes(complexes) # XXX don't sort until you are sure that it is compatible # with the indexing method but assert that the desired state # is not broken C, F = 0, 1 # location of ComplexInterval and factor fs = set([i[F] for i in complexes]) for i in range(1, len(complexes)): if complexes[i][F] != complexes[i - 1][F]: # if this fails the factors of a root were not # contiguous because a discontinuity should only # happen once fs.remove(complexes[i - 1][F]) for i in range(len(complexes)): # negative im part (conj=True) comes before # positive im part (conj=False) assert complexes[i][C].conj is (i % 2 == 0) # update cache cache = {} # -- collate for root, currentfactor, _ in complexes: cache.setdefault(currentfactor, []).append(root) # -- store for currentfactor, root in cache.items(): _complexes_cache[currentfactor] = root return complexes @classmethod def _reals_index(cls, reals, index): """ Map initial real root index to an index in a factor where the root belongs. """ i = 0 for j, (_, currentfactor, k) in enumerate(reals): if index < i + k: poly, index = currentfactor, 0 for _, currentfactor, _ in reals[:j]: if currentfactor == poly: index += 1 return poly, index else: i += k @classmethod def _complexes_index(cls, complexes, index): """ Map initial complex root index to an index in a factor where the root belongs. """ i = 0 for j, (_, currentfactor, k) in enumerate(complexes): if index < i + k: poly, index = currentfactor, 0 for _, currentfactor, _ in complexes[:j]: if currentfactor == poly: index += 1 index += len(_reals_cache[poly]) return poly, index else: i += k @classmethod def _count_roots(cls, roots): """Count the number of real or complex roots with multiplicities.""" return sum([k for _, _, k in roots]) @classmethod def _indexed_root(cls, poly, index): """Get a root of a composite polynomial by index. """ factors = _pure_factors(poly) reals = cls._get_reals(factors) reals_count = cls._count_roots(reals) if index < reals_count: return cls._reals_index(reals, index) else: complexes = cls._get_complexes(factors) return cls._complexes_index(complexes, index - reals_count) @classmethod def _real_roots(cls, poly): """Get real roots of a composite polynomial. """ factors = _pure_factors(poly) reals = cls._get_reals(factors) reals_count = cls._count_roots(reals) roots = [] for index in range(0, reals_count): roots.append(cls._reals_index(reals, index)) return roots def _reset(self): self._all_roots(self.poly, use_cache=False) @classmethod def _all_roots(cls, poly, use_cache=True): """Get real and complex roots of a composite polynomial. """ factors = _pure_factors(poly) reals = cls._get_reals(factors, use_cache=use_cache) reals_count = cls._count_roots(reals) roots = [] for index in range(0, reals_count): roots.append(cls._reals_index(reals, index)) complexes = cls._get_complexes(factors, use_cache=use_cache) complexes_count = cls._count_roots(complexes) for index in range(0, complexes_count): roots.append(cls._complexes_index(complexes, index)) return roots @classmethod @cacheit def _roots_trivial(cls, poly, radicals): """Compute roots in linear, quadratic and binomial cases. """ if poly.degree() == 1: return roots_linear(poly) if not radicals: return None if poly.degree() == 2: return roots_quadratic(poly) elif poly.length() == 2 and poly.TC(): return roots_binomial(poly) else: return None @classmethod def _preprocess_roots(cls, poly): """Take heroic measures to make ``poly`` compatible with ``CRootOf``.""" dom = poly.get_domain() if not dom.is_Exact: poly = poly.to_exact() coeff, poly = preprocess_roots(poly) dom = poly.get_domain() if not dom.is_ZZ: raise NotImplementedError( "sorted roots not supported over %s" % dom) return coeff, poly @classmethod def _postprocess_root(cls, root, radicals): """Return the root if it is trivial or a ``CRootOf`` object. """ poly, index = root roots = cls._roots_trivial(poly, radicals) if roots is not None: return roots[index] else: return cls._new(poly, index) @classmethod def _get_roots(cls, method, poly, radicals): """Return postprocessed roots of specified kind. """ if not poly.is_univariate: raise PolynomialError("only univariate polynomials are allowed") coeff, poly = cls._preprocess_roots(poly) roots = [] for root in getattr(cls, method)(poly): roots.append(coeffcls._postprocess_root(root, radicals)) return roots @classmethod def clear_cache(cls): """Reset cache for reals and complexes. The intervals used to approximate a root instance are updated as needed. When a request is made to see the intervals, the most current values are shown. `clear_cache` will reset all CRootOf instances back to their original state. See Also ======== _reset """ global _reals_cache, _complexes_cache _reals_cache = _pure_key_dict() _complexes_cache = _pure_key_dict() def _get_interval(self): """Internal function for retrieving isolation interval from cache. """ if self.is_real: return _reals_cache[self.poly][self.index] else: reals_count = len(_reals_cache[self.poly]) return _complexes_cache[self.poly][self.index - reals_count] def _set_interval(self, interval): """Internal function for updating isolation interval in cache. """ if self.is_real: _reals_cache[self.poly][self.index] = interval else: reals_count = len(_reals_cache[self.poly]) _complexes_cache[self.poly][self.index - reals_count] = interval def _eval_subs(self, old, new): # don't allow subs to change anything return self def _eval_conjugate(self): if self.is_real: return self expr, i = self.args return self.func(expr, i + (1 if self._get_interval().conj else -1)) def eval_approx(self, n): """Evaluate this complex root to the given precision. This uses secant method and root bounds are used to both generate an initial guess and to check that the root returned is valid. If ever the method converges outside the root bounds, the bounds will be made smaller and updated. """ prec = dps_to_prec(n) with workprec(prec): g = self.poly.gen if not g.is_Symbol: d = Dummy('x') if self.is_imaginary: d = I func = lambdify(d, self.expr.subs(g, d)) else: expr = self.expr if self.is_imaginary: expr = self.expr.subs(g, Ig) func = lambdify(g, expr) interval = self._get_interval() while True: if self.is_real: a = mpf(str(interval.a)) b = mpf(str(interval.b)) if a == b: root = a break x0 = mpf(str(interval.center)) x1 = x0 + mpf(str(interval.dx))/4 elif self.is_imaginary: a = mpf(str(interval.ay)) b = mpf(str(interval.by)) if a == b: root = mpc(mpf('0'), a) break x0 = mpf(str(interval.center[1])) x1 = x0 + mpf(str(interval.dy))/4 else: ax = mpf(str(interval.ax)) bx = mpf(str(interval.bx)) ay = mpf(str(interval.ay)) by = mpf(str(interval.by)) if ax == bx and ay == by: root = mpc(ax, ay) break x0 = mpc(map(str, interval.center)) x1 = x0 + mpc(map(str, (interval.dx, interval.dy)))/4 try: # without a tolerance, this will return when (to within # the given precision) x_i == x_{i-1} root = findroot(func, (x0, x1)) # If the (real or complex) root is not in the 'interval', # then keep refining the interval. This happens if findroot # accidentally finds a different root outside of this # interval because our initial estimate 'x0' was not close # enough. It is also possible that the secant method will # get trapped by a max/min in the interval; the root # verification by findroot will raise a ValueError in this # case and the interval will then be tightened -- and # eventually the root will be found. # # It is also possible that findroot will not have any # successful iterations to process (in which case it # will fail to initialize a variable that is tested # after the iterations and raise an UnboundLocalError). if self.is_real or self.is_imaginary: if not bool(root.imag) == self.is_real and ( a <= root <= b): if self.is_imaginary: root = mpc(mpf('0'), root.real) break elif (ax <= root.real <= bx and ay <= root.imag <= by): break except (UnboundLocalError, ValueError): pass interval = interval.refine() # update the interval so we at least (for this precision or # less) don't have much work to do to recompute the root self._set_interval(interval) return (Float._new(root.real._mpf_, prec) + IFloat._new(root.imag._mpf_, prec)) def _eval_evalf(self, prec, kwargs): """Evaluate this complex root to the given precision.""" # all kwargs are ignored return self.eval_rational(n=prec_to_dps(prec))._evalf(prec) def eval_rational(self, dx=None, dy=None, n=15): """ Return a Rational approximation of ``self`` that has real and imaginary component approximations that are within ``dx`` and ``dy`` of the true values, respectively. Alternatively, ``n`` digits of precision can be specified. The interval is refined with bisection and is sure to converge. The root bounds are updated when the refinement is complete so recalculation at the same or lesser precision will not have to repeat the refinement and should be much faster. The following example first obtains Rational approximation to 1e-8 accuracy for all roots of the 4-th order Legendre polynomial. Since the roots are all less than 1, this will ensure the decimal representation of the approximation will be correct (including rounding) to 6 digits: >>> from sympy import S, legendre_poly, Symbol >>> x = Symbol("x") >>> p = legendre_poly(4, x, polys=True) >>> r = p.real_roots()[-1] >>> r.eval_rational(10-8).n(6) 0.861136 It is not necessary to a two-step calculation, however: the decimal representation can be computed directly: >>> r.evalf(17) 0.86113631159405258 """ dy = dy or dx if dx: rtol = None dx = dx if isinstance(dx, Rational) else Rational(str(dx)) dy = dy if isinstance(dy, Rational) else Rational(str(dy)) else: # 5 binary (or 2 decimal) digits are needed to ensure that # a given digit is correctly rounded # prec_to_dps(dps_to_prec(n) + 5) - n <= 2 (tested for # n in range(1000000) rtol = S(10)*-(n + 2) # +2 for guard digits interval = self._get_interval() while True: if self.is_real: if rtol: dx = abs(interval.centerrtol) interval = interval.refine_size(dx=dx) c = interval.center real = Rational(c) imag = S.Zero if not rtol or interval.dx < abs(crtol): break elif self.is_imaginary: if rtol: dy = abs(interval.center[1]rtol) dx = 1 interval = interval.refine_size(dx=dx, dy=dy) c = interval.center[1] imag = Rational(c) real = S.Zero if not rtol or interval.dy < abs(crtol): break else: if rtol: dx = abs(interval.center[0]rtol) dy = abs(interval.center[1]rtol) interval = interval.refine_size(dx, dy) c = interval.center real, imag = map(Rational, c) if not rtol or ( interval.dx < abs(c[0]rtol) and interval.dy < abs(c[1]rtol)): break # update the interval so we at least (for this precision or # less) don't have much work to do to recompute the root self._set_interval(interval) return real + Iimag def _eval_Eq(self, other): # CRootOf represents a Root, so if other is that root, it should set # the expression to zero and it should be in the interval of the # CRootOf instance. It must also be a number that agrees with the # is_real value of the CRootOf instance. if type(self) == type(other): return sympify(self == other) if not (other.is_number and not other.has(AppliedUndef)): return S.false if not other.is_finite: return S.false z = self.expr.subs(self.expr.free_symbols.pop(), other).is_zero if z is False: # all roots will make z True but we don't know # whether this is the right root if z is True return S.false o = other.is_real, other.is_imaginary s = self.is_real, self.is_imaginary assert None not in s # this is part of initial refinement if o != s and None not in o: return S.false re, im = other.as_real_imag() if self.is_real: if im: return S.false i = self._get_interval() a, b = [Rational(str(_)) for _ in (i.a, i.b)] return sympify(a <= other and other <= b) i = self._get_interval() r1, r2, i1, i2 = [Rational(str(j)) for j in ( i.ax, i.bx, i.ay, i.by)] return sympify(( r1 <= re and re <= r2) and ( i1 <= im and im <= i2)) CRootOf = ComplexRootOf @public class RootSum(Expr): """Represents a sum of all roots of a univariate polynomial. """ __slots__ = ['poly', 'fun', 'auto'] def __new__(cls, expr, func=None, x=None, auto=True, quadratic=False): """Construct a new ``RootSum`` instance of roots of a polynomial.""" coeff, poly = cls._transform(expr, x) if not poly.is_univariate: raise MultivariatePolynomialError( "only univariate polynomials are allowed") if func is None: func = Lambda(poly.gen, poly.gen) else: try: is_func = func.is_Function except AttributeError: is_func = False if is_func and 1 in func.nargs: if not isinstance(func, Lambda): func = Lambda(poly.gen, func(poly.gen)) else: raise ValueError( "expected a univariate function, got %s" % func) var, expr = func.variables[0], func.expr if coeff is not S.One: expr = expr.subs(var, coeffvar) deg = poly.degree() if not expr.has(var): return degexpr if expr.is_Add: add_const, expr = expr.as_independent(var) else: add_const = S.Zero if expr.is_Mul: mul_const, expr = expr.as_independent(var) else: mul_const = S.One func = Lambda(var, expr) rational = cls._is_func_rational(poly, func) factors, terms = _pure_factors(poly), [] for poly, k in factors: if poly.is_linear: term = func(roots_linear(poly)[0]) elif quadratic and poly.is_quadratic: term = sum(map(func, roots_quadratic(poly))) else: if not rational or not auto: term = cls._new(poly, func, auto) else: term = cls._rational_case(poly, func) terms.append(kterm) return mul_constAdd(terms) + degadd_const @classmethod def _new(cls, poly, func, auto=True): """Construct new raw ``RootSum`` instance. """ obj = Expr.__new__(cls) obj.poly = poly obj.fun = func obj.auto = auto return obj @classmethod def new(cls, poly, func, auto=True): """Construct new ``RootSum`` instance. """ if not func.expr.has(func.variables): return func.expr rational = cls._is_func_rational(poly, func) if not rational or not auto: return cls._new(poly, func, auto) else: return cls._rational_case(poly, func) @classmethod def _transform(cls, expr, x): """Transform an expression to a polynomial. """ poly = PurePoly(expr, x, greedy=False) return preprocess_roots(poly) @classmethod def _is_func_rational(cls, poly, func): """Check if a lambda is a rational function. """ var, expr = func.variables[0], func.expr return expr.is_rational_function(var) @classmethod def _rational_case(cls, poly, func): """Handle the rational function case. """ roots = symbols('r:%d' % poly.degree()) var, expr = func.variables[0], func.expr f = sum(expr.subs(var, r) for r in roots) p, q = together(f).as_numer_denom() domain = QQ[roots] p = p.expand() q = q.expand() try: p = Poly(p, domain=domain, expand=False) except GeneratorsNeeded: p, p_coeff = None, (p,) else: p_monom, p_coeff = zip(p.terms()) try: q = Poly(q, domain=domain, expand=False) except GeneratorsNeeded: q, q_coeff = None, (q,) else: q_monom, q_coeff = zip(q.terms()) coeffs, mapping = symmetrize(p_coeff + q_coeff, formal=True) formulas, values = viete(poly, roots), [] for (sym, _), (_, val) in zip(mapping, formulas): values.append((sym, val)) for i, (coeff, _) in enumerate(coeffs): coeffs[i] = coeff.subs(values) n = len(p_coeff) p_coeff = coeffs[:n] q_coeff = coeffs[n:] if p is not None: p = Poly(dict(zip(p_monom, p_coeff)), p.gens).as_expr() else: (p,) = p_coeff if q is not None: q = Poly(dict(zip(q_monom, q_coeff)), q.gens).as_expr() else: (q,) = q_coeff return factor(p/q) def _hashable_content(self): return (self.poly, self.fun) @property def expr(self): return self.poly.as_expr() @property def args(self): return (self.expr, self.fun, self.poly.gen) @property def free_symbols(self): return self.poly.free_symbols \| self.fun.free_symbols @property def is_commutative(self): return True def doit(self, hints): if not hints.get('roots', True): return self _roots = roots(self.poly, multiple=True) if len(_roots) < self.poly.degree(): return self else: return Add([self.fun(r) for r in _roots]) def _eval_evalf(self, prec): try: _roots = self.poly.nroots(n=prec_to_dps(prec)) except (DomainError, PolynomialError): return self else: return Add(*[self.fun(r) for r in _roots]) def _eval_derivative(self, x): var, expr = self.fun.args func = Lambda(var, expr.diff(x)) return self.new(self.poly, func, self.auto)
a4d17263800c1ea9f1d31a74cf7cfc8dd86fca967cefbd1505fb2cfee5242308	"""Square-free decomposition algorithms and related tools. """ from __future__ import print_function, division from sympy.polys.densearith import ( dup_neg, dmp_neg, dup_sub, dmp_sub, dup_mul, dup_quo, dmp_quo, dup_mul_ground, dmp_mul_ground) from sympy.polys.densebasic import ( dup_strip, dup_LC, dmp_ground_LC, dmp_zero_p, dmp_ground, dup_degree, dmp_degree, dmp_raise, dmp_inject, dup_convert) from sympy.polys.densetools import ( dup_diff, dmp_diff, dup_shift, dmp_compose, dup_monic, dmp_ground_monic, dup_primitive, dmp_ground_primitive) from sympy.polys.euclidtools import ( dup_inner_gcd, dmp_inner_gcd, dup_gcd, dmp_gcd, dmp_resultant) from sympy.polys.galoistools import ( gf_sqf_list, gf_sqf_part) from sympy.polys.polyerrors import ( MultivariatePolynomialError, DomainError) def dup_sqf_p(f, K): """ Return ``True`` if ``f`` is a square-free polynomial in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_sqf_p(x*2 - 2x + 1) False >>> R.dup_sqf_p(x2 - 1) True """ if not f: return True else: return not dup_degree(dup_gcd(f, dup_diff(f, 1, K), K)) def dmp_sqf_p(f, u, K): """ Return ``True`` if ``f`` is a square-free polynomial in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_sqf_p(x2 + 2xy + y2) False >>> R.dmp_sqf_p(x2 + y2) True """ if dmp_zero_p(f, u): return True else: return not dmp_degree(dmp_gcd(f, dmp_diff(f, 1, u, K), u, K), u) def dup_sqf_norm(f, K): """ Square-free norm of ``f`` in ``K[x]``, useful over algebraic domains. Returns ``s``, ``f``, ``r``, such that ``g(x) = f(x-sa)`` and ``r(x) = Norm(g(x))`` is a square-free polynomial over K, where ``a`` is the algebraic extension of ``K``. Examples ======== >>> from sympy.polys import ring, QQ >>> from sympy import sqrt >>> K = QQ.algebraic_field(sqrt(3)) >>> R, x = ring("x", K) >>> _, X = ring("x", QQ) >>> s, f, r = R.dup_sqf_norm(x2 - 2) >>> s == 1 True >>> f == x*2 + K([QQ(-2), QQ(0)])x + 1 True >>> r == X*4 - 10X*2 + 1 True """ if not K.is_Algebraic: raise DomainError("ground domain must be algebraic") s, g = 0, dmp_raise(K.mod.rep, 1, 0, K.dom) while True: h, _ = dmp_inject(f, 0, K, front=True) r = dmp_resultant(g, h, 1, K.dom) if dup_sqf_p(r, K.dom): break else: f, s = dup_shift(f, -K.unit, K), s + 1 return s, f, r def dmp_sqf_norm(f, u, K): """ Square-free norm of ``f`` in ``K[X]``, useful over algebraic domains. Returns ``s``, ``f``, ``r``, such that ``g(x) = f(x-sa)`` and ``r(x) = Norm(g(x))`` is a square-free polynomial over K, where ``a`` is the algebraic extension of ``K``. Examples ======== >>> from sympy.polys import ring, QQ >>> from sympy import I >>> K = QQ.algebraic_field(I) >>> R, x, y = ring("x,y", K) >>> _, X, Y = ring("x,y", QQ) >>> s, f, r = R.dmp_sqf_norm(xy + y*2) >>> s == 1 True >>> f == xy + y*2 + K([QQ(-1), QQ(0)])y True >>> r == X*2Y*2 + 2XY3 + Y4 + Y2 True """ if not u: return dup_sqf_norm(f, K) if not K.is_Algebraic: raise DomainError("ground domain must be algebraic") g = dmp_raise(K.mod.rep, u + 1, 0, K.dom) F = dmp_raise([K.one, -K.unit], u, 0, K) s = 0 while True: h, _ = dmp_inject(f, u, K, front=True) r = dmp_resultant(g, h, u + 1, K.dom) if dmp_sqf_p(r, u, K.dom): break else: f, s = dmp_compose(f, F, u, K), s + 1 return s, f, r def dmp_norm(f, u, K): """ Norm of ``f`` in ``K[X1, ..., Xn]``, often not square-free. """ if not K.is_Algebraic: raise DomainError("ground domain must be algebraic") g = dmp_raise(K.mod.rep, u + 1, 0, K.dom) h, _ = dmp_inject(f, u, K, front=True) return dmp_resultant(g, h, u + 1, K.dom) def dup_gf_sqf_part(f, K): """Compute square-free part of ``f`` in ``GF(p)[x]``. """ f = dup_convert(f, K, K.dom) g = gf_sqf_part(f, K.mod, K.dom) return dup_convert(g, K.dom, K) def dmp_gf_sqf_part(f, K): """Compute square-free part of ``f`` in ``GF(p)[X]``. """ raise NotImplementedError('multivariate polynomials over finite fields') def dup_sqf_part(f, K): """ Returns square-free part of a polynomial in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_sqf_part(x3 - 3x - 2) x2 - x - 2 """ if K.is_FiniteField: return dup_gf_sqf_part(f, K) if not f: return f if K.is_negative(dup_LC(f, K)): f = dup_neg(f, K) gcd = dup_gcd(f, dup_diff(f, 1, K), K) sqf = dup_quo(f, gcd, K) if K.is_Field: return dup_monic(sqf, K) else: return dup_primitive(sqf, K)[1] def dmp_sqf_part(f, u, K): """ Returns square-free part of a polynomial in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_sqf_part(x3 + 2x2y + xy2) x2 + xy """ if not u: return dup_sqf_part(f, K) if K.is_FiniteField: return dmp_gf_sqf_part(f, u, K) if dmp_zero_p(f, u): return f if K.is_negative(dmp_ground_LC(f, u, K)): f = dmp_neg(f, u, K) gcd = dmp_gcd(f, dmp_diff(f, 1, u, K), u, K) sqf = dmp_quo(f, gcd, u, K) if K.is_Field: return dmp_ground_monic(sqf, u, K) else: return dmp_ground_primitive(sqf, u, K)[1] def dup_gf_sqf_list(f, K, all=False): """Compute square-free decomposition of ``f`` in ``GF(p)[x]``. """ f = dup_convert(f, K, K.dom) coeff, factors = gf_sqf_list(f, K.mod, K.dom, all=all) for i, (f, k) in enumerate(factors): factors[i] = (dup_convert(f, K.dom, K), k) return K.convert(coeff, K.dom), factors def dmp_gf_sqf_list(f, u, K, all=False): """Compute square-free decomposition of ``f`` in ``GF(p)[X]``. """ raise NotImplementedError('multivariate polynomials over finite fields') def dup_sqf_list(f, K, all=False): """ Return square-free decomposition of a polynomial in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> f = 2x5 + 16x*4 + 50x*3 + 76x*2 + 56x + 16 >>> R.dup_sqf_list(f) (2, [(x + 1, 2), (x + 2, 3)]) >>> R.dup_sqf_list(f, all=True) (2, [(1, 1), (x + 1, 2), (x + 2, 3)]) """ if K.is_FiniteField: return dup_gf_sqf_list(f, K, all=all) if K.is_Field: coeff = dup_LC(f, K) f = dup_monic(f, K) else: coeff, f = dup_primitive(f, K) if K.is_negative(dup_LC(f, K)): f = dup_neg(f, K) coeff = -coeff if dup_degree(f) <= 0: return coeff, [] result, i = [], 1 h = dup_diff(f, 1, K) g, p, q = dup_inner_gcd(f, h, K) while True: d = dup_diff(p, 1, K) h = dup_sub(q, d, K) if not h: result.append((p, i)) break g, p, q = dup_inner_gcd(p, h, K) if all or dup_degree(g) > 0: result.append((g, i)) i += 1 return coeff, result def dup_sqf_list_include(f, K, all=False): """ Return square-free decomposition of a polynomial in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> f = 2x5 + 16x*4 + 50x*3 + 76x*2 + 56x + 16 >>> R.dup_sqf_list_include(f) [(2, 1), (x + 1, 2), (x + 2, 3)] >>> R.dup_sqf_list_include(f, all=True) [(2, 1), (x + 1, 2), (x + 2, 3)] """ coeff, factors = dup_sqf_list(f, K, all=all) if factors and factors[0][1] == 1: g = dup_mul_ground(factors[0][0], coeff, K) return [(g, 1)] + factors[1:] else: g = dup_strip([coeff]) return [(g, 1)] + factors def dmp_sqf_list(f, u, K, all=False): """ Return square-free decomposition of a polynomial in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = x*5 + 2x*4y + x*3y2 >>> R.dmp_sqf_list(f) (1, [(x + y, 2), (x, 3)]) >>> R.dmp_sqf_list(f, all=True) (1, [(1, 1), (x + y, 2), (x, 3)]) """ if not u: return dup_sqf_list(f, K, all=all) if K.is_FiniteField: return dmp_gf_sqf_list(f, u, K, all=all) if K.is_Field: coeff = dmp_ground_LC(f, u, K) f = dmp_ground_monic(f, u, K) else: coeff, f = dmp_ground_primitive(f, u, K) if K.is_negative(dmp_ground_LC(f, u, K)): f = dmp_neg(f, u, K) coeff = -coeff if dmp_degree(f, u) <= 0: return coeff, [] result, i = [], 1 h = dmp_diff(f, 1, u, K) g, p, q = dmp_inner_gcd(f, h, u, K) while True: d = dmp_diff(p, 1, u, K) h = dmp_sub(q, d, u, K) if dmp_zero_p(h, u): result.append((p, i)) break g, p, q = dmp_inner_gcd(p, h, u, K) if all or dmp_degree(g, u) > 0: result.append((g, i)) i += 1 return coeff, result def dmp_sqf_list_include(f, u, K, all=False): """ Return square-free decomposition of a polynomial in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = x5 + 2x4y + x*3y2 >>> R.dmp_sqf_list_include(f) [(1, 1), (x + y, 2), (x, 3)] >>> R.dmp_sqf_list_include(f, all=True) [(1, 1), (x + y, 2), (x, 3)] """ if not u: return dup_sqf_list_include(f, K, all=all) coeff, factors = dmp_sqf_list(f, u, K, all=all) if factors and factors[0][1] == 1: g = dmp_mul_ground(factors[0][0], coeff, u, K) return [(g, 1)] + factors[1:] else: g = dmp_ground(coeff, u) return [(g, 1)] + factors def dup_gff_list(f, K): """ Compute greatest factorial factorization of ``f`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_gff_list(x5 + 2x4 - x3 - 2x**2) [(x, 1), (x + 2, 4)] """ if not f: raise ValueError("greatest factorial factorization doesn't exist for a zero polynomial") f = dup_monic(f, K) if not dup_degree(f): return [] else: g = dup_gcd(f, dup_shift(f, K.one, K), K) H = dup_gff_list(g, K) for i, (h, k) in enumerate(H): g = dup_mul(g, dup_shift(h, -K(k), K), K) H[i] = (h, k + 1) f = dup_quo(f, g, K) if not dup_degree(f): return H else: return [(f, 1)] + H def dmp_gff_list(f, u, K): """ Compute greatest factorial factorization of ``f`` in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) """ if not u: return dup_gff_list(f, K) else: raise MultivariatePolynomialError(f)
fc6c2ad1f01568a3a0ed6d376dffc083aae0f537b20a92c70fabc6e50dc4edd3	"""Advanced tools for dense recursive polynomials in ``K[x]`` or ``K[X]``. """ from __future__ import print_function, division from sympy.core.compatibility import range from sympy.polys.densearith import ( dup_add_term, dmp_add_term, dup_lshift, dup_add, dmp_add, dup_sub, dmp_sub, dup_mul, dmp_mul, dup_sqr, dup_div, dup_rem, dmp_rem, dmp_expand, dup_mul_ground, dmp_mul_ground, dup_quo_ground, dmp_quo_ground, dup_exquo_ground, dmp_exquo_ground, ) from sympy.polys.densebasic import ( dup_strip, dmp_strip, dup_convert, dmp_convert, dup_degree, dmp_degree, dmp_to_dict, dmp_from_dict, dup_LC, dmp_LC, dmp_ground_LC, dup_TC, dmp_TC, dmp_zero, dmp_ground, dmp_zero_p, dup_to_raw_dict, dup_from_raw_dict, dmp_zeros ) from sympy.polys.polyerrors import ( MultivariatePolynomialError, DomainError ) from sympy.utilities import variations from math import ceil as _ceil, log as _log def dup_integrate(f, m, K): """ Computes the indefinite integral of ``f`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x = ring("x", QQ) >>> R.dup_integrate(x*2 + 2x, 1) 1/3x3 + x2 >>> R.dup_integrate(x2 + 2x, 2) 1/12x4 + 1/3x*3 """ if m <= 0 or not f: return f g = [K.zero]m for i, c in enumerate(reversed(f)): n = i + 1 for j in range(1, m): n = i + j + 1 g.insert(0, K.exquo(c, K(n))) return g def dmp_integrate(f, m, u, K): """ Computes the indefinite integral of ``f`` in ``x_0`` in ``K[X]``. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x,y = ring("x,y", QQ) >>> R.dmp_integrate(x + 2y, 1) 1/2x2 + 2xy >>> R.dmp_integrate(x + 2y, 2) 1/6x3 + x2y """ if not u: return dup_integrate(f, m, K) if m <= 0 or dmp_zero_p(f, u): return f g, v = dmp_zeros(m, u - 1, K), u - 1 for i, c in enumerate(reversed(f)): n = i + 1 for j in range(1, m): n = i + j + 1 g.insert(0, dmp_quo_ground(c, K(n), v, K)) return g def _rec_integrate_in(g, m, v, i, j, K): """Recursive helper for :func:`dmp_integrate_in`.""" if i == j: return dmp_integrate(g, m, v, K) w, i = v - 1, i + 1 return dmp_strip([ _rec_integrate_in(c, m, w, i, j, K) for c in g ], v) def dmp_integrate_in(f, m, j, u, K): """ Computes the indefinite integral of ``f`` in ``x_j`` in ``K[X]``. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x,y = ring("x,y", QQ) >>> R.dmp_integrate_in(x + 2y, 1, 0) 1/2x2 + 2xy >>> R.dmp_integrate_in(x + 2y, 1, 1) xy + y2 """ if j < 0 or j > u: raise IndexError("0 <= j <= u expected, got u = %d, j = %d" % (u, j)) return _rec_integrate_in(f, m, u, 0, j, K) def dup_diff(f, m, K): """ ``m``-th order derivative of a polynomial in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_diff(x3 + 2x*2 + 3x + 4, 1) 3x2 + 4x + 3 >>> R.dup_diff(x*3 + 2x*2 + 3x + 4, 2) 6x + 4 """ if m <= 0: return f n = dup_degree(f) if n < m: return [] deriv = [] if m == 1: for coeff in f[:-m]: deriv.append(K(n)coeff) n -= 1 else: for coeff in f[:-m]: k = n for i in range(n - 1, n - m, -1): k = i deriv.append(K(k)coeff) n -= 1 return dup_strip(deriv) def dmp_diff(f, m, u, K): """ ``m``-th order derivative in ``x_0`` of a polynomial in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = xy2 + 2xy + 3x + 2y2 + 3y + 1 >>> R.dmp_diff(f, 1) y*2 + 2y + 3 >>> R.dmp_diff(f, 2) 0 """ if not u: return dup_diff(f, m, K) if m <= 0: return f n = dmp_degree(f, u) if n < m: return dmp_zero(u) deriv, v = [], u - 1 if m == 1: for coeff in f[:-m]: deriv.append(dmp_mul_ground(coeff, K(n), v, K)) n -= 1 else: for coeff in f[:-m]: k = n for i in range(n - 1, n - m, -1): k = i deriv.append(dmp_mul_ground(coeff, K(k), v, K)) n -= 1 return dmp_strip(deriv, u) def _rec_diff_in(g, m, v, i, j, K): """Recursive helper for :func:`dmp_diff_in`.""" if i == j: return dmp_diff(g, m, v, K) w, i = v - 1, i + 1 return dmp_strip([ _rec_diff_in(c, m, w, i, j, K) for c in g ], v) def dmp_diff_in(f, m, j, u, K): """ ``m``-th order derivative in ``x_j`` of a polynomial in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = xy*2 + 2xy + 3x + 2y2 + 3y + 1 >>> R.dmp_diff_in(f, 1, 0) y*2 + 2y + 3 >>> R.dmp_diff_in(f, 1, 1) 2xy + 2x + 4y + 3 """ if j < 0 or j > u: raise IndexError("0 <= j <= %s expected, got %s" % (u, j)) return _rec_diff_in(f, m, u, 0, j, K) def dup_eval(f, a, K): """ Evaluate a polynomial at ``x = a`` in ``K[x]`` using Horner scheme. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_eval(x*2 + 2x + 3, 2) 11 """ if not a: return dup_TC(f, K) result = K.zero for c in f: result = a result += c return result def dmp_eval(f, a, u, K): """ Evaluate a polynomial at ``x_0 = a`` in ``K[X]`` using the Horner scheme. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_eval(2xy + 3x + y + 2, 2) 5y + 8 """ if not u: return dup_eval(f, a, K) if not a: return dmp_TC(f, K) result, v = dmp_LC(f, K), u - 1 for coeff in f[1:]: result = dmp_mul_ground(result, a, v, K) result = dmp_add(result, coeff, v, K) return result def _rec_eval_in(g, a, v, i, j, K): """Recursive helper for :func:`dmp_eval_in`.""" if i == j: return dmp_eval(g, a, v, K) v, i = v - 1, i + 1 return dmp_strip([ _rec_eval_in(c, a, v, i, j, K) for c in g ], v) def dmp_eval_in(f, a, j, u, K): """ Evaluate a polynomial at ``x_j = a`` in ``K[X]`` using the Horner scheme. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = 2xy + 3x + y + 2 >>> R.dmp_eval_in(f, 2, 0) 5y + 8 >>> R.dmp_eval_in(f, 2, 1) 7x + 4 """ if j < 0 or j > u: raise IndexError("0 <= j <= %s expected, got %s" % (u, j)) return _rec_eval_in(f, a, u, 0, j, K) def _rec_eval_tail(g, i, A, u, K): """Recursive helper for :func:`dmp_eval_tail`.""" if i == u: return dup_eval(g, A[-1], K) else: h = [ _rec_eval_tail(c, i + 1, A, u, K) for c in g ] if i < u - len(A) + 1: return h else: return dup_eval(h, A[-u + i - 1], K) def dmp_eval_tail(f, A, u, K): """ Evaluate a polynomial at ``x_j = a_j, ...`` in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = 2xy + 3x + y + 2 >>> R.dmp_eval_tail(f, [2]) 7x + 4 >>> R.dmp_eval_tail(f, [2, 2]) 18 """ if not A: return f if dmp_zero_p(f, u): return dmp_zero(u - len(A)) e = _rec_eval_tail(f, 0, A, u, K) if u == len(A) - 1: return e else: return dmp_strip(e, u - len(A)) def _rec_diff_eval(g, m, a, v, i, j, K): """Recursive helper for :func:`dmp_diff_eval`.""" if i == j: return dmp_eval(dmp_diff(g, m, v, K), a, v, K) v, i = v - 1, i + 1 return dmp_strip([ _rec_diff_eval(c, m, a, v, i, j, K) for c in g ], v) def dmp_diff_eval_in(f, m, a, j, u, K): """ Differentiate and evaluate a polynomial in ``x_j`` at ``a`` in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = xy2 + 2xy + 3x + 2y2 + 3y + 1 >>> R.dmp_diff_eval_in(f, 1, 2, 0) y*2 + 2y + 3 >>> R.dmp_diff_eval_in(f, 1, 2, 1) 6x + 11 """ if j > u: raise IndexError("-%s <= j < %s expected, got %s" % (u, u, j)) if not j: return dmp_eval(dmp_diff(f, m, u, K), a, u, K) return _rec_diff_eval(f, m, a, u, 0, j, K) def dup_trunc(f, p, K): """ Reduce a ``K[x]`` polynomial modulo a constant ``p`` in ``K``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_trunc(2x*3 + 3x*2 + 5x + 7, ZZ(3)) -x*3 - x + 1 """ if K.is_ZZ: g = [] for c in f: c = c % p if c > p // 2: g.append(c - p) else: g.append(c) else: g = [ c % p for c in f ] return dup_strip(g) def dmp_trunc(f, p, u, K): """ Reduce a ``K[X]`` polynomial modulo a polynomial ``p`` in ``K[Y]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = 3x*2y + 8x2 + 5xy + 6x + 2y + 3 >>> g = (y - 1).drop(x) >>> R.dmp_trunc(f, g) 11x*2 + 11x + 5 """ return dmp_strip([ dmp_rem(c, p, u - 1, K) for c in f ], u) def dmp_ground_trunc(f, p, u, K): """ Reduce a ``K[X]`` polynomial modulo a constant ``p`` in ``K``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = 3x2y + 8x2 + 5xy + 6x + 2y + 3 >>> R.dmp_ground_trunc(f, ZZ(3)) -x2 - xy - y """ if not u: return dup_trunc(f, p, K) v = u - 1 return dmp_strip([ dmp_ground_trunc(c, p, v, K) for c in f ], u) def dup_monic(f, K): """ Divide all coefficients by ``LC(f)`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ, QQ >>> R, x = ring("x", ZZ) >>> R.dup_monic(3x2 + 6x + 9) x*2 + 2x + 3 >>> R, x = ring("x", QQ) >>> R.dup_monic(3x2 + 4x + 2) x*2 + 4/3x + 2/3 """ if not f: return f lc = dup_LC(f, K) if K.is_one(lc): return f else: return dup_exquo_ground(f, lc, K) def dmp_ground_monic(f, u, K): """ Divide all coefficients by ``LC(f)`` in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ, QQ >>> R, x,y = ring("x,y", ZZ) >>> f = 3x2y + 6x2 + 3xy + 9y + 3 >>> R.dmp_ground_monic(f) x*2y + 2x2 + xy + 3y + 1 >>> R, x,y = ring("x,y", QQ) >>> f = 3x*2y + 8x2 + 5xy + 6x + 2y + 3 >>> R.dmp_ground_monic(f) x2y + 8/3x2 + 5/3xy + 2x + 2/3y + 1 """ if not u: return dup_monic(f, K) if dmp_zero_p(f, u): return f lc = dmp_ground_LC(f, u, K) if K.is_one(lc): return f else: return dmp_exquo_ground(f, lc, u, K) def dup_content(f, K): """ Compute the GCD of coefficients of ``f`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ, QQ >>> R, x = ring("x", ZZ) >>> f = 6x*2 + 8x + 12 >>> R.dup_content(f) 2 >>> R, x = ring("x", QQ) >>> f = 6x2 + 8x + 12 >>> R.dup_content(f) 2 """ from sympy.polys.domains import QQ if not f: return K.zero cont = K.zero if K == QQ: for c in f: cont = K.gcd(cont, c) else: for c in f: cont = K.gcd(cont, c) if K.is_one(cont): break return cont def dmp_ground_content(f, u, K): """ Compute the GCD of coefficients of ``f`` in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ, QQ >>> R, x,y = ring("x,y", ZZ) >>> f = 2xy + 6x + 4y + 12 >>> R.dmp_ground_content(f) 2 >>> R, x,y = ring("x,y", QQ) >>> f = 2xy + 6x + 4y + 12 >>> R.dmp_ground_content(f) 2 """ from sympy.polys.domains import QQ if not u: return dup_content(f, K) if dmp_zero_p(f, u): return K.zero cont, v = K.zero, u - 1 if K == QQ: for c in f: cont = K.gcd(cont, dmp_ground_content(c, v, K)) else: for c in f: cont = K.gcd(cont, dmp_ground_content(c, v, K)) if K.is_one(cont): break return cont def dup_primitive(f, K): """ Compute content and the primitive form of ``f`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ, QQ >>> R, x = ring("x", ZZ) >>> f = 6x2 + 8x + 12 >>> R.dup_primitive(f) (2, 3x2 + 4x + 6) >>> R, x = ring("x", QQ) >>> f = 6x2 + 8x + 12 >>> R.dup_primitive(f) (2, 3x2 + 4x + 6) """ if not f: return K.zero, f cont = dup_content(f, K) if K.is_one(cont): return cont, f else: return cont, dup_quo_ground(f, cont, K) def dmp_ground_primitive(f, u, K): """ Compute content and the primitive form of ``f`` in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ, QQ >>> R, x,y = ring("x,y", ZZ) >>> f = 2xy + 6x + 4y + 12 >>> R.dmp_ground_primitive(f) (2, xy + 3x + 2y + 6) >>> R, x,y = ring("x,y", QQ) >>> f = 2xy + 6x + 4y + 12 >>> R.dmp_ground_primitive(f) (2, xy + 3x + 2y + 6) """ if not u: return dup_primitive(f, K) if dmp_zero_p(f, u): return K.zero, f cont = dmp_ground_content(f, u, K) if K.is_one(cont): return cont, f else: return cont, dmp_quo_ground(f, cont, u, K) def dup_extract(f, g, K): """ Extract common content from a pair of polynomials in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_extract(6x2 + 12x + 18, 4x2 + 8x + 12) (2, 3x2 + 6x + 9, 2x2 + 4x + 6) """ fc = dup_content(f, K) gc = dup_content(g, K) gcd = K.gcd(fc, gc) if not K.is_one(gcd): f = dup_quo_ground(f, gcd, K) g = dup_quo_ground(g, gcd, K) return gcd, f, g def dmp_ground_extract(f, g, u, K): """ Extract common content from a pair of polynomials in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_ground_extract(6xy + 12x + 18, 4xy + 8x + 12) (2, 3xy + 6x + 9, 2xy + 4x + 6) """ fc = dmp_ground_content(f, u, K) gc = dmp_ground_content(g, u, K) gcd = K.gcd(fc, gc) if not K.is_one(gcd): f = dmp_quo_ground(f, gcd, u, K) g = dmp_quo_ground(g, gcd, u, K) return gcd, f, g def dup_real_imag(f, K): """ Return bivariate polynomials ``f1`` and ``f2``, such that ``f = f1 + f2I``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dup_real_imag(x3 + x2 + x + 1) (x3 + x2 - 3xy2 + x - y2 + 1, 3x*2y + 2xy - y3 + y) """ if not K.is_ZZ and not K.is_QQ: raise DomainError("computing real and imaginary parts is not supported over %s" % K) f1 = dmp_zero(1) f2 = dmp_zero(1) if not f: return f1, f2 g = [[[K.one, K.zero]], [[K.one], []]] h = dmp_ground(f[0], 2) for c in f[1:]: h = dmp_mul(h, g, 2, K) h = dmp_add_term(h, dmp_ground(c, 1), 0, 2, K) H = dup_to_raw_dict(h) for k, h in H.items(): m = k % 4 if not m: f1 = dmp_add(f1, h, 1, K) elif m == 1: f2 = dmp_add(f2, h, 1, K) elif m == 2: f1 = dmp_sub(f1, h, 1, K) else: f2 = dmp_sub(f2, h, 1, K) return f1, f2 def dup_mirror(f, K): """ Evaluate efficiently the composition ``f(-x)`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_mirror(x3 + 2x2 - 4x + 2) -x*3 + 2x*2 + 4x + 2 """ f = list(f) for i in range(len(f) - 2, -1, -2): f[i] = -f[i] return f def dup_scale(f, a, K): """ Evaluate efficiently composition ``f(ax)`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_scale(x2 - 2x + 1, ZZ(2)) 4x2 - 4x + 1 """ f, n, b = list(f), len(f) - 1, a for i in range(n - 1, -1, -1): f[i], b = bf[i], ba return f def dup_shift(f, a, K): """ Evaluate efficiently Taylor shift ``f(x + a)`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_shift(x*2 - 2x + 1, ZZ(2)) x*2 + 2x + 1 """ f, n = list(f), len(f) - 1 for i in range(n, 0, -1): for j in range(0, i): f[j + 1] += af[j] return f def dup_transform(f, p, q, K): """ Evaluate functional transformation ``qn f(p/q)`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_transform(x*2 - 2x + 1, x2 + 1, x - 1) x4 - 2x3 + 5x*2 - 4x + 4 """ if not f: return [] n = len(f) - 1 h, Q = [f[0]], [[K.one]] for i in range(0, n): Q.append(dup_mul(Q[-1], q, K)) for c, q in zip(f[1:], Q[1:]): h = dup_mul(h, p, K) q = dup_mul_ground(q, c, K) h = dup_add(h, q, K) return h def dup_compose(f, g, K): """ Evaluate functional composition ``f(g)`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_compose(x2 + x, x - 1) x2 - x """ if len(g) <= 1: return dup_strip([dup_eval(f, dup_LC(g, K), K)]) if not f: return [] h = [f[0]] for c in f[1:]: h = dup_mul(h, g, K) h = dup_add_term(h, c, 0, K) return h def dmp_compose(f, g, u, K): """ Evaluate functional composition ``f(g)`` in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_compose(xy + 2x + y, y) y*2 + 3y """ if not u: return dup_compose(f, g, K) if dmp_zero_p(f, u): return f h = [f[0]] for c in f[1:]: h = dmp_mul(h, g, u, K) h = dmp_add_term(h, c, 0, u, K) return h def _dup_right_decompose(f, s, K): """Helper function for :func:`_dup_decompose`.""" n = len(f) - 1 lc = dup_LC(f, K) f = dup_to_raw_dict(f) g = { s: K.one } r = n // s for i in range(1, s): coeff = K.zero for j in range(0, i): if not n + j - i in f: continue if not s - j in g: continue fc, gc = f[n + j - i], g[s - j] coeff += (i - rj)fcgc g[s - i] = K.quo(coeff, irlc) return dup_from_raw_dict(g, K) def _dup_left_decompose(f, h, K): """Helper function for :func:`_dup_decompose`.""" g, i = {}, 0 while f: q, r = dup_div(f, h, K) if dup_degree(r) > 0: return None else: g[i] = dup_LC(r, K) f, i = q, i + 1 return dup_from_raw_dict(g, K) def _dup_decompose(f, K): """Helper function for :func:`dup_decompose`.""" df = len(f) - 1 for s in range(2, df): if df % s != 0: continue h = _dup_right_decompose(f, s, K) if h is not None: g = _dup_left_decompose(f, h, K) if g is not None: return g, h return None def dup_decompose(f, K): """ Computes functional decomposition of ``f`` in ``K[x]``. Given a univariate polynomial ``f`` with coefficients in a field of characteristic zero, returns list ``[f_1, f_2, ..., f_n]``, where:: f = f_1 o f_2 o ... f_n = f_1(f_2(... f_n)) and ``f_2, ..., f_n`` are monic and homogeneous polynomials of at least second degree. Unlike factorization, complete functional decompositions of polynomials are not unique, consider examples: 1. ``f o g = f(x + b) o (g - b)`` 2. ``xn o xm = xm o xn`` 3. ``T_n o T_m = T_m o T_n`` where ``T_n`` and ``T_m`` are Chebyshev polynomials. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_decompose(x4 - 2x3 + x2) [x2, x2 - x] References ========== .. [1] [Kozen89]_ """ F = [] while True: result = _dup_decompose(f, K) if result is not None: f, h = result F = [h] + F else: break return [f] + F def dmp_lift(f, u, K): """ Convert algebraic coefficients to integers in ``K[X]``. Examples ======== >>> from sympy.polys import ring, QQ >>> from sympy import I >>> K = QQ.algebraic_field(I) >>> R, x = ring("x", K) >>> f = x*2 + K([QQ(1), QQ(0)])x + K([QQ(2), QQ(0)]) >>> R.dmp_lift(f) x*8 + 2x*6 + 9x*4 - 8x2 + 16 """ if not K.is_Algebraic: raise DomainError( 'computation can be done only in an algebraic domain') F, monoms, polys = dmp_to_dict(f, u), [], [] for monom, coeff in F.items(): if not coeff.is_ground: monoms.append(monom) perms = variations([-1, 1], len(monoms), repetition=True) for perm in perms: G = dict(F) for sign, monom in zip(perm, monoms): if sign == -1: G[monom] = -G[monom] polys.append(dmp_from_dict(G, u, K)) return dmp_convert(dmp_expand(polys, u, K), u, K, K.dom) def dup_sign_variations(f, K): """ Compute the number of sign variations of ``f`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_sign_variations(x4 - x*2 - x + 1) 2 """ prev, k = K.zero, 0 for coeff in f: if K.is_negative(coeffprev): k += 1 if coeff: prev = coeff return k def dup_clear_denoms(f, K0, K1=None, convert=False): """ Clear denominators, i.e. transform ``K_0`` to ``K_1``. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x = ring("x", QQ) >>> f = QQ(1,2)x + QQ(1,3) >>> R.dup_clear_denoms(f, convert=False) (6, 3x + 2) >>> R.dup_clear_denoms(f, convert=True) (6, 3x + 2) """ if K1 is None: if K0.has_assoc_Ring: K1 = K0.get_ring() else: K1 = K0 common = K1.one for c in f: common = K1.lcm(common, K0.denom(c)) if not K1.is_one(common): f = dup_mul_ground(f, common, K0) if not convert: return common, f else: return common, dup_convert(f, K0, K1) def _rec_clear_denoms(g, v, K0, K1): """Recursive helper for :func:`dmp_clear_denoms`.""" common = K1.one if not v: for c in g: common = K1.lcm(common, K0.denom(c)) else: w = v - 1 for c in g: common = K1.lcm(common, _rec_clear_denoms(c, w, K0, K1)) return common def dmp_clear_denoms(f, u, K0, K1=None, convert=False): """ Clear denominators, i.e. transform ``K_0`` to ``K_1``. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x,y = ring("x,y", QQ) >>> f = QQ(1,2)x + QQ(1,3)y + 1 >>> R.dmp_clear_denoms(f, convert=False) (6, 3x + 2y + 6) >>> R.dmp_clear_denoms(f, convert=True) (6, 3x + 2y + 6) """ if not u: return dup_clear_denoms(f, K0, K1, convert=convert) if K1 is None: if K0.has_assoc_Ring: K1 = K0.get_ring() else: K1 = K0 common = _rec_clear_denoms(f, u, K0, K1) if not K1.is_one(common): f = dmp_mul_ground(f, common, u, K0) if not convert: return common, f else: return common, dmp_convert(f, u, K0, K1) def dup_revert(f, n, K): """ Compute ``f(-1)`` mod ``xn`` using Newton iteration. This function computes first ``2n`` terms of a polynomial that is a result of inversion of a polynomial modulo ``xn``. This is useful to efficiently compute series expansion of ``1/f``. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x = ring("x", QQ) >>> f = -QQ(1,720)x*6 + QQ(1,24)x*4 - QQ(1,2)x*2 + 1 >>> R.dup_revert(f, 8) 61/720x*6 + 5/24x*4 + 1/2x2 + 1 """ g = [K.revert(dup_TC(f, K))] h = [K.one, K.zero, K.zero] N = int(_ceil(_log(n, 2))) for i in range(1, N + 1): a = dup_mul_ground(g, K(2), K) b = dup_mul(f, dup_sqr(g, K), K) g = dup_rem(dup_sub(a, b, K), h, K) h = dup_lshift(h, dup_degree(h), K) return g def dmp_revert(f, g, u, K): """ Compute ``f(-1)`` mod ``x**n`` using Newton iteration. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x,y = ring("x,y", QQ) """ if not u: return dup_revert(f, g, K) else: raise MultivariatePolynomialError(f, g)
7a07862a4d60b2a1f661e10149139338289777fd5b1ad6fdd11b9caea786c9c6	"""User-friendly public interface to polynomial functions. """ from __future__ import print_function, division from sympy.core import ( S, Basic, Expr, I, Integer, Add, Mul, Dummy, Tuple ) from sympy.core.basic import preorder_traversal from sympy.core.compatibility import iterable, range, ordered from sympy.core.decorators import _sympifyit from sympy.core.function import Derivative from sympy.core.mul import _keep_coeff from sympy.core.relational import Relational from sympy.core.symbol import Symbol from sympy.core.sympify import sympify from sympy.logic.boolalg import BooleanAtom from sympy.polys import polyoptions as options from sympy.polys.constructor import construct_domain from sympy.polys.domains import FF, QQ, ZZ from sympy.polys.fglmtools import matrix_fglm from sympy.polys.groebnertools import groebner as _groebner from sympy.polys.monomials import Monomial from sympy.polys.orderings import monomial_key from sympy.polys.polyclasses import DMP from sympy.polys.polyerrors import ( OperationNotSupported, DomainError, CoercionFailed, UnificationFailed, GeneratorsNeeded, PolynomialError, MultivariatePolynomialError, ExactQuotientFailed, PolificationFailed, ComputationFailed, GeneratorsError, ) from sympy.polys.polyutils import ( basic_from_dict, _sort_gens, _unify_gens, _dict_reorder, _dict_from_expr, _parallel_dict_from_expr, ) from sympy.polys.rationaltools import together from sympy.polys.rootisolation import dup_isolate_real_roots_list from sympy.utilities import group, sift, public, filldedent # Required to avoid errors import sympy.polys import mpmath from mpmath.libmp.libhyper import NoConvergence @public class Poly(Expr): """ Generic class for representing and operating on polynomial expressions. Subclasses Expr class. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y Create a univariate polynomial: >>> Poly(x(x2 + x - 1)2) Poly(x5 + 2x4 - x3 - 2x2 + x, x, domain='ZZ') Create a univariate polynomial with specific domain: >>> from sympy import sqrt >>> Poly(x2 + 2x + sqrt(3), domain='R') Poly(1.0x2 + 2.0x + 1.73205080756888, x, domain='RR') Create a multivariate polynomial: >>> Poly(yx2 + xy + 1) Poly(x*2y + xy + 1, x, y, domain='ZZ') Create a univariate polynomial, where y is a constant: >>> Poly(yx*2 + xy + 1,x) Poly(yx2 + yx + 1, x, domain='ZZ[y]') You can evaluate the above polynomial as a function of y: >>> Poly(yx2 + xy + 1,x).eval(2) 6y + 1 See Also ======== sympy.core.expr.Expr """ __slots__ = ['rep', 'gens'] is_commutative = True is_Poly = True _op_priority = 10.001 def __new__(cls, rep, gens, *args): """Create a new polynomial instance out of something useful. """ opt = options.build_options(gens, args) if 'order' in opt: raise NotImplementedError("'order' keyword is not implemented yet") if iterable(rep, exclude=str): if isinstance(rep, dict): return cls._from_dict(rep, opt) else: return cls._from_list(list(rep), opt) else: rep = sympify(rep) if rep.is_Poly: return cls._from_poly(rep, opt) else: return cls._from_expr(rep, opt) @classmethod def new(cls, rep, gens): """Construct :class:`Poly` instance from raw representation. """ if not isinstance(rep, DMP): raise PolynomialError( "invalid polynomial representation: %s" % rep) elif rep.lev != len(gens) - 1: raise PolynomialError("invalid arguments: %s, %s" % (rep, gens)) obj = Basic.__new__(cls) obj.rep = rep obj.gens = gens return obj @classmethod def from_dict(cls, rep, gens, args): """Construct a polynomial from a ``dict``. """ opt = options.build_options(gens, args) return cls._from_dict(rep, opt) @classmethod def from_list(cls, rep, gens, *args): """Construct a polynomial from a ``list``. """ opt = options.build_options(gens, args) return cls._from_list(rep, opt) @classmethod def from_poly(cls, rep, gens, *args): """Construct a polynomial from a polynomial. """ opt = options.build_options(gens, args) return cls._from_poly(rep, opt) @classmethod def from_expr(cls, rep, gens, *args): """Construct a polynomial from an expression. """ opt = options.build_options(gens, args) return cls._from_expr(rep, opt) @classmethod def _from_dict(cls, rep, opt): """Construct a polynomial from a ``dict``. """ gens = opt.gens if not gens: raise GeneratorsNeeded( "can't initialize from 'dict' without generators") level = len(gens) - 1 domain = opt.domain if domain is None: domain, rep = construct_domain(rep, opt=opt) else: for monom, coeff in rep.items(): rep[monom] = domain.convert(coeff) return cls.new(DMP.from_dict(rep, level, domain), gens) @classmethod def _from_list(cls, rep, opt): """Construct a polynomial from a ``list``. """ gens = opt.gens if not gens: raise GeneratorsNeeded( "can't initialize from 'list' without generators") elif len(gens) != 1: raise MultivariatePolynomialError( "'list' representation not supported") level = len(gens) - 1 domain = opt.domain if domain is None: domain, rep = construct_domain(rep, opt=opt) else: rep = list(map(domain.convert, rep)) return cls.new(DMP.from_list(rep, level, domain), gens) @classmethod def _from_poly(cls, rep, opt): """Construct a polynomial from a polynomial. """ if cls != rep.__class__: rep = cls.new(rep.rep, rep.gens) gens = opt.gens field = opt.field domain = opt.domain if gens and rep.gens != gens: if set(rep.gens) != set(gens): return cls._from_expr(rep.as_expr(), opt) else: rep = rep.reorder(gens) if 'domain' in opt and domain: rep = rep.set_domain(domain) elif field is True: rep = rep.to_field() return rep @classmethod def _from_expr(cls, rep, opt): """Construct a polynomial from an expression. """ rep, opt = _dict_from_expr(rep, opt) return cls._from_dict(rep, opt) def _hashable_content(self): """Allow SymPy to hash Poly instances. """ return (self.rep, self.gens) def __hash__(self): return super(Poly, self).__hash__() @property def free_symbols(self): """ Free symbols of a polynomial expression. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y, z >>> Poly(x2 + 1).free_symbols {x} >>> Poly(x2 + y).free_symbols {x, y} >>> Poly(x2 + y, x).free_symbols {x, y} >>> Poly(x2 + y, x, z).free_symbols {x, y} """ symbols = set() gens = self.gens for i in range(len(gens)): for monom in self.monoms(): if monom[i]: symbols \|= gens[i].free_symbols break return symbols \| self.free_symbols_in_domain @property def free_symbols_in_domain(self): """ Free symbols of the domain of ``self``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x2 + 1).free_symbols_in_domain set() >>> Poly(x2 + y).free_symbols_in_domain set() >>> Poly(x2 + y, x).free_symbols_in_domain {y} """ domain, symbols = self.rep.dom, set() if domain.is_Composite: for gen in domain.symbols: symbols \|= gen.free_symbols elif domain.is_EX: for coeff in self.coeffs(): symbols \|= coeff.free_symbols return symbols @property def args(self): """ Don't mess up with the core. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x2 + 1, x).args (x2 + 1,) """ return (self.as_expr(),) @property def gen(self): """ Return the principal generator. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x2 + 1, x).gen x """ return self.gens[0] @property def domain(self): """Get the ground domain of ``self``. """ return self.get_domain() @property def zero(self): """Return zero polynomial with ``self``'s properties. """ return self.new(self.rep.zero(self.rep.lev, self.rep.dom), self.gens) @property def one(self): """Return one polynomial with ``self``'s properties. """ return self.new(self.rep.one(self.rep.lev, self.rep.dom), self.gens) @property def unit(self): """Return unit polynomial with ``self``'s properties. """ return self.new(self.rep.unit(self.rep.lev, self.rep.dom), self.gens) def unify(f, g): """ Make ``f`` and ``g`` belong to the same domain. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> f, g = Poly(x/2 + 1), Poly(2x + 1) >>> f Poly(1/2x + 1, x, domain='QQ') >>> g Poly(2x + 1, x, domain='ZZ') >>> F, G = f.unify(g) >>> F Poly(1/2x + 1, x, domain='QQ') >>> G Poly(2x + 1, x, domain='QQ') """ _, per, F, G = f._unify(g) return per(F), per(G) def _unify(f, g): g = sympify(g) if not g.is_Poly: try: return f.rep.dom, f.per, f.rep, f.rep.per(f.rep.dom.from_sympy(g)) except CoercionFailed: raise UnificationFailed("can't unify %s with %s" % (f, g)) if isinstance(f.rep, DMP) and isinstance(g.rep, DMP): gens = _unify_gens(f.gens, g.gens) dom, lev = f.rep.dom.unify(g.rep.dom, gens), len(gens) - 1 if f.gens != gens: f_monoms, f_coeffs = _dict_reorder( f.rep.to_dict(), f.gens, gens) if f.rep.dom != dom: f_coeffs = [dom.convert(c, f.rep.dom) for c in f_coeffs] F = DMP(dict(list(zip(f_monoms, f_coeffs))), dom, lev) else: F = f.rep.convert(dom) if g.gens != gens: g_monoms, g_coeffs = _dict_reorder( g.rep.to_dict(), g.gens, gens) if g.rep.dom != dom: g_coeffs = [dom.convert(c, g.rep.dom) for c in g_coeffs] G = DMP(dict(list(zip(g_monoms, g_coeffs))), dom, lev) else: G = g.rep.convert(dom) else: raise UnificationFailed("can't unify %s with %s" % (f, g)) cls = f.__class__ def per(rep, dom=dom, gens=gens, remove=None): if remove is not None: gens = gens[:remove] + gens[remove + 1:] if not gens: return dom.to_sympy(rep) return cls.new(rep, gens) return dom, per, F, G def per(f, rep, gens=None, remove=None): """ Create a Poly out of the given representation. Examples ======== >>> from sympy import Poly, ZZ >>> from sympy.abc import x, y >>> from sympy.polys.polyclasses import DMP >>> a = Poly(x*2 + 1) >>> a.per(DMP([ZZ(1), ZZ(1)], ZZ), gens=[y]) Poly(y + 1, y, domain='ZZ') """ if gens is None: gens = f.gens if remove is not None: gens = gens[:remove] + gens[remove + 1:] if not gens: return f.rep.dom.to_sympy(rep) return f.__class__.new(rep, gens) def set_domain(f, domain): """Set the ground domain of ``f``. """ opt = options.build_options(f.gens, {'domain': domain}) return f.per(f.rep.convert(opt.domain)) def get_domain(f): """Get the ground domain of ``f``. """ return f.rep.dom def set_modulus(f, modulus): """ Set the modulus of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(5x2 + 2x - 1, x).set_modulus(2) Poly(x2 + 1, x, modulus=2) """ modulus = options.Modulus.preprocess(modulus) return f.set_domain(FF(modulus)) def get_modulus(f): """ Get the modulus of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x2 + 1, modulus=2).get_modulus() 2 """ domain = f.get_domain() if domain.is_FiniteField: return Integer(domain.characteristic()) else: raise PolynomialError("not a polynomial over a Galois field") def _eval_subs(f, old, new): """Internal implementation of :func:`subs`. """ if old in f.gens: if new.is_number: return f.eval(old, new) else: try: return f.replace(old, new) except PolynomialError: pass return f.as_expr().subs(old, new) def exclude(f): """ Remove unnecessary generators from ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import a, b, c, d, x >>> Poly(a + x, a, b, c, d, x).exclude() Poly(a + x, a, x, domain='ZZ') """ J, new = f.rep.exclude() gens = [] for j in range(len(f.gens)): if j not in J: gens.append(f.gens[j]) return f.per(new, gens=gens) def replace(f, x, y=None, _ignore): # XXX this does not match Basic's signature """ Replace ``x`` with ``y`` in generators list. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x2 + 1, x).replace(x, y) Poly(y2 + 1, y, domain='ZZ') """ if y is None: if f.is_univariate: x, y = f.gen, x else: raise PolynomialError( "syntax supported only in univariate case") if x == y or x not in f.gens: return f if x in f.gens and y not in f.gens: dom = f.get_domain() if not dom.is_Composite or y not in dom.symbols: gens = list(f.gens) gens[gens.index(x)] = y return f.per(f.rep, gens=gens) raise PolynomialError("can't replace %s with %s in %s" % (x, y, f)) def reorder(f, gens, args): """ Efficiently apply new order of generators. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x2 + xy2, x, y).reorder(y, x) Poly(y2x + x*2, y, x, domain='ZZ') """ opt = options.Options((), args) if not gens: gens = _sort_gens(f.gens, opt=opt) elif set(f.gens) != set(gens): raise PolynomialError( "generators list can differ only up to order of elements") rep = dict(list(zip(_dict_reorder(f.rep.to_dict(), f.gens, gens)))) return f.per(DMP(rep, f.rep.dom, len(gens) - 1), gens=gens) def ltrim(f, gen): """ Remove dummy generators from ``f`` that are to the left of specified ``gen`` in the generators as ordered. When ``gen`` is an integer, it refers to the generator located at that position within the tuple of generators of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y, z >>> Poly(y*2 + yz2, x, y, z).ltrim(y) Poly(y2 + yz2, y, z, domain='ZZ') >>> Poly(z, x, y, z).ltrim(-1) Poly(z, z, domain='ZZ') """ rep = f.as_dict(native=True) j = f._gen_to_level(gen) terms = {} for monom, coeff in rep.items(): if any(i for i in monom[:j]): # some generator is used in the portion to be trimmed raise PolynomialError("can't left trim %s" % f) terms[monom[j:]] = coeff gens = f.gens[j:] return f.new(DMP.from_dict(terms, len(gens) - 1, f.rep.dom), gens) def has_only_gens(f, gens): """ Return ``True`` if ``Poly(f, gens)`` retains ground domain. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y, z >>> Poly(xy + 1, x, y, z).has_only_gens(x, y) True >>> Poly(xy + z, x, y, z).has_only_gens(x, y) False """ indices = set() for gen in gens: try: index = f.gens.index(gen) except ValueError: raise GeneratorsError( "%s doesn't have %s as generator" % (f, gen)) else: indices.add(index) for monom in f.monoms(): for i, elt in enumerate(monom): if i not in indices and elt: return False return True def to_ring(f): """ Make the ground domain a ring. Examples ======== >>> from sympy import Poly, QQ >>> from sympy.abc import x >>> Poly(x2 + 1, domain=QQ).to_ring() Poly(x2 + 1, x, domain='ZZ') """ if hasattr(f.rep, 'to_ring'): result = f.rep.to_ring() else: # pragma: no cover raise OperationNotSupported(f, 'to_ring') return f.per(result) def to_field(f): """ Make the ground domain a field. Examples ======== >>> from sympy import Poly, ZZ >>> from sympy.abc import x >>> Poly(x2 + 1, x, domain=ZZ).to_field() Poly(x2 + 1, x, domain='QQ') """ if hasattr(f.rep, 'to_field'): result = f.rep.to_field() else: # pragma: no cover raise OperationNotSupported(f, 'to_field') return f.per(result) def to_exact(f): """ Make the ground domain exact. Examples ======== >>> from sympy import Poly, RR >>> from sympy.abc import x >>> Poly(x2 + 1.0, x, domain=RR).to_exact() Poly(x2 + 1, x, domain='QQ') """ if hasattr(f.rep, 'to_exact'): result = f.rep.to_exact() else: # pragma: no cover raise OperationNotSupported(f, 'to_exact') return f.per(result) def retract(f, field=None): """ Recalculate the ground domain of a polynomial. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> f = Poly(x2 + 1, x, domain='QQ[y]') >>> f Poly(x2 + 1, x, domain='QQ[y]') >>> f.retract() Poly(x2 + 1, x, domain='ZZ') >>> f.retract(field=True) Poly(x2 + 1, x, domain='QQ') """ dom, rep = construct_domain(f.as_dict(zero=True), field=field, composite=f.domain.is_Composite or None) return f.from_dict(rep, f.gens, domain=dom) def slice(f, x, m, n=None): """Take a continuous subsequence of terms of ``f``. """ if n is None: j, m, n = 0, x, m else: j = f._gen_to_level(x) m, n = int(m), int(n) if hasattr(f.rep, 'slice'): result = f.rep.slice(m, n, j) else: # pragma: no cover raise OperationNotSupported(f, 'slice') return f.per(result) def coeffs(f, order=None): """ Returns all non-zero coefficients from ``f`` in lex order. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x*3 + 2x + 3, x).coeffs() [1, 2, 3] See Also ======== all_coeffs coeff_monomial nth """ return [f.rep.dom.to_sympy(c) for c in f.rep.coeffs(order=order)] def monoms(f, order=None): """ Returns all non-zero monomials from ``f`` in lex order. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x*2 + 2xy2 + xy + 3y, x, y).monoms() [(2, 0), (1, 2), (1, 1), (0, 1)] See Also ======== all_monoms """ return f.rep.monoms(order=order) def terms(f, order=None): """ Returns all non-zero terms from ``f`` in lex order. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x2 + 2xy2 + xy + 3y, x, y).terms() [((2, 0), 1), ((1, 2), 2), ((1, 1), 1), ((0, 1), 3)] See Also ======== all_terms """ return [(m, f.rep.dom.to_sympy(c)) for m, c in f.rep.terms(order=order)] def all_coeffs(f): """ Returns all coefficients from a univariate polynomial ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x3 + 2x - 1, x).all_coeffs() [1, 0, 2, -1] """ return [f.rep.dom.to_sympy(c) for c in f.rep.all_coeffs()] def all_monoms(f): """ Returns all monomials from a univariate polynomial ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x*3 + 2x - 1, x).all_monoms() [(3,), (2,), (1,), (0,)] See Also ======== all_terms """ return f.rep.all_monoms() def all_terms(f): """ Returns all terms from a univariate polynomial ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x*3 + 2x - 1, x).all_terms() [((3,), 1), ((2,), 0), ((1,), 2), ((0,), -1)] """ return [(m, f.rep.dom.to_sympy(c)) for m, c in f.rep.all_terms()] def termwise(f, func, gens, args): """ Apply a function to all terms of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> def func(k, coeff): ... k = k[0] ... return coeff//10(2-k) >>> Poly(x2 + 20x + 400).termwise(func) Poly(x*2 + 2x + 4, x, domain='ZZ') """ terms = {} for monom, coeff in f.terms(): result = func(monom, coeff) if isinstance(result, tuple): monom, coeff = result else: coeff = result if coeff: if monom not in terms: terms[monom] = coeff else: raise PolynomialError( "%s monomial was generated twice" % monom) return f.from_dict(terms, (gens or f.gens), args) def length(f): """ Returns the number of non-zero terms in ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x2 + 2x - 1).length() 3 """ return len(f.as_dict()) def as_dict(f, native=False, zero=False): """ Switch to a ``dict`` representation. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x*2 + 2xy2 - y, x, y).as_dict() {(0, 1): -1, (1, 2): 2, (2, 0): 1} """ if native: return f.rep.to_dict(zero=zero) else: return f.rep.to_sympy_dict(zero=zero) def as_list(f, native=False): """Switch to a ``list`` representation. """ if native: return f.rep.to_list() else: return f.rep.to_sympy_list() def as_expr(f, gens): """ Convert a Poly instance to an Expr instance. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> f = Poly(x*2 + 2xy2 - y, x, y) >>> f.as_expr() x2 + 2xy2 - y >>> f.as_expr({x: 5}) 10y*2 - y + 25 >>> f.as_expr(5, 6) 379 """ if not gens: gens = f.gens elif len(gens) == 1 and isinstance(gens[0], dict): mapping = gens[0] gens = list(f.gens) for gen, value in mapping.items(): try: index = gens.index(gen) except ValueError: raise GeneratorsError( "%s doesn't have %s as generator" % (f, gen)) else: gens[index] = value return basic_from_dict(f.rep.to_sympy_dict(), gens) def lift(f): """ Convert algebraic coefficients to rationals. Examples ======== >>> from sympy import Poly, I >>> from sympy.abc import x >>> Poly(x*2 + Ix + 1, x, extension=I).lift() Poly(x*4 + 3x2 + 1, x, domain='QQ') """ if hasattr(f.rep, 'lift'): result = f.rep.lift() else: # pragma: no cover raise OperationNotSupported(f, 'lift') return f.per(result) def deflate(f): """ Reduce degree of ``f`` by mapping ``x_im`` to ``y_i``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x*6y2 + x3 + 1, x, y).deflate() ((3, 2), Poly(x*2y + x + 1, x, y, domain='ZZ')) """ if hasattr(f.rep, 'deflate'): J, result = f.rep.deflate() else: # pragma: no cover raise OperationNotSupported(f, 'deflate') return J, f.per(result) def inject(f, front=False): """ Inject ground domain generators into ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> f = Poly(x*2y + xy3 + xy + 1, x) >>> f.inject() Poly(x*2y + xy3 + xy + 1, x, y, domain='ZZ') >>> f.inject(front=True) Poly(y*3x + yx2 + yx + 1, y, x, domain='ZZ') """ dom = f.rep.dom if dom.is_Numerical: return f elif not dom.is_Poly: raise DomainError("can't inject generators over %s" % dom) if hasattr(f.rep, 'inject'): result = f.rep.inject(front=front) else: # pragma: no cover raise OperationNotSupported(f, 'inject') if front: gens = dom.symbols + f.gens else: gens = f.gens + dom.symbols return f.new(result, gens) def eject(f, gens): """ Eject selected generators into the ground domain. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> f = Poly(x*2y + xy3 + xy + 1, x, y) >>> f.eject(x) Poly(xy3 + (x2 + x)y + 1, y, domain='ZZ[x]') >>> f.eject(y) Poly(yx2 + (y3 + y)x + 1, x, domain='ZZ[y]') """ dom = f.rep.dom if not dom.is_Numerical: raise DomainError("can't eject generators over %s" % dom) k = len(gens) if f.gens[:k] == gens: _gens, front = f.gens[k:], True elif f.gens[-k:] == gens: _gens, front = f.gens[:-k], False else: raise NotImplementedError( "can only eject front or back generators") dom = dom.inject(gens) if hasattr(f.rep, 'eject'): result = f.rep.eject(dom, front=front) else: # pragma: no cover raise OperationNotSupported(f, 'eject') return f.new(result, _gens) def terms_gcd(f): """ Remove GCD of terms from the polynomial ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x*6y2 + x3y, x, y).terms_gcd() ((3, 1), Poly(x3y + 1, x, y, domain='ZZ')) """ if hasattr(f.rep, 'terms_gcd'): J, result = f.rep.terms_gcd() else: # pragma: no cover raise OperationNotSupported(f, 'terms_gcd') return J, f.per(result) def add_ground(f, coeff): """ Add an element of the ground domain to ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x + 1).add_ground(2) Poly(x + 3, x, domain='ZZ') """ if hasattr(f.rep, 'add_ground'): result = f.rep.add_ground(coeff) else: # pragma: no cover raise OperationNotSupported(f, 'add_ground') return f.per(result) def sub_ground(f, coeff): """ Subtract an element of the ground domain from ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x + 1).sub_ground(2) Poly(x - 1, x, domain='ZZ') """ if hasattr(f.rep, 'sub_ground'): result = f.rep.sub_ground(coeff) else: # pragma: no cover raise OperationNotSupported(f, 'sub_ground') return f.per(result) def mul_ground(f, coeff): """ Multiply ``f`` by a an element of the ground domain. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x + 1).mul_ground(2) Poly(2x + 2, x, domain='ZZ') """ if hasattr(f.rep, 'mul_ground'): result = f.rep.mul_ground(coeff) else: # pragma: no cover raise OperationNotSupported(f, 'mul_ground') return f.per(result) def quo_ground(f, coeff): """ Quotient of ``f`` by a an element of the ground domain. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(2x + 4).quo_ground(2) Poly(x + 2, x, domain='ZZ') >>> Poly(2x + 3).quo_ground(2) Poly(x + 1, x, domain='ZZ') """ if hasattr(f.rep, 'quo_ground'): result = f.rep.quo_ground(coeff) else: # pragma: no cover raise OperationNotSupported(f, 'quo_ground') return f.per(result) def exquo_ground(f, coeff): """ Exact quotient of ``f`` by a an element of the ground domain. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(2x + 4).exquo_ground(2) Poly(x + 2, x, domain='ZZ') >>> Poly(2x + 3).exquo_ground(2) Traceback (most recent call last): ... ExactQuotientFailed: 2 does not divide 3 in ZZ """ if hasattr(f.rep, 'exquo_ground'): result = f.rep.exquo_ground(coeff) else: # pragma: no cover raise OperationNotSupported(f, 'exquo_ground') return f.per(result) def abs(f): """ Make all coefficients in ``f`` positive. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x2 - 1, x).abs() Poly(x2 + 1, x, domain='ZZ') """ if hasattr(f.rep, 'abs'): result = f.rep.abs() else: # pragma: no cover raise OperationNotSupported(f, 'abs') return f.per(result) def neg(f): """ Negate all coefficients in ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x2 - 1, x).neg() Poly(-x2 + 1, x, domain='ZZ') >>> -Poly(x2 - 1, x) Poly(-x2 + 1, x, domain='ZZ') """ if hasattr(f.rep, 'neg'): result = f.rep.neg() else: # pragma: no cover raise OperationNotSupported(f, 'neg') return f.per(result) def add(f, g): """ Add two polynomials ``f`` and ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x2 + 1, x).add(Poly(x - 2, x)) Poly(x2 + x - 1, x, domain='ZZ') >>> Poly(x2 + 1, x) + Poly(x - 2, x) Poly(x2 + x - 1, x, domain='ZZ') """ g = sympify(g) if not g.is_Poly: return f.add_ground(g) _, per, F, G = f._unify(g) if hasattr(f.rep, 'add'): result = F.add(G) else: # pragma: no cover raise OperationNotSupported(f, 'add') return per(result) def sub(f, g): """ Subtract two polynomials ``f`` and ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x2 + 1, x).sub(Poly(x - 2, x)) Poly(x2 - x + 3, x, domain='ZZ') >>> Poly(x2 + 1, x) - Poly(x - 2, x) Poly(x2 - x + 3, x, domain='ZZ') """ g = sympify(g) if not g.is_Poly: return f.sub_ground(g) _, per, F, G = f._unify(g) if hasattr(f.rep, 'sub'): result = F.sub(G) else: # pragma: no cover raise OperationNotSupported(f, 'sub') return per(result) def mul(f, g): """ Multiply two polynomials ``f`` and ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x2 + 1, x).mul(Poly(x - 2, x)) Poly(x3 - 2x2 + x - 2, x, domain='ZZ') >>> Poly(x2 + 1, x)Poly(x - 2, x) Poly(x3 - 2x2 + x - 2, x, domain='ZZ') """ g = sympify(g) if not g.is_Poly: return f.mul_ground(g) _, per, F, G = f._unify(g) if hasattr(f.rep, 'mul'): result = F.mul(G) else: # pragma: no cover raise OperationNotSupported(f, 'mul') return per(result) def sqr(f): """ Square a polynomial ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x - 2, x).sqr() Poly(x2 - 4x + 4, x, domain='ZZ') >>> Poly(x - 2, x)2 Poly(x2 - 4x + 4, x, domain='ZZ') """ if hasattr(f.rep, 'sqr'): result = f.rep.sqr() else: # pragma: no cover raise OperationNotSupported(f, 'sqr') return f.per(result) def pow(f, n): """ Raise ``f`` to a non-negative power ``n``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x - 2, x).pow(3) Poly(x*3 - 6x*2 + 12x - 8, x, domain='ZZ') >>> Poly(x - 2, x)3 Poly(x3 - 6x2 + 12x - 8, x, domain='ZZ') """ n = int(n) if hasattr(f.rep, 'pow'): result = f.rep.pow(n) else: # pragma: no cover raise OperationNotSupported(f, 'pow') return f.per(result) def pdiv(f, g): """ Polynomial pseudo-division of ``f`` by ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x*2 + 1, x).pdiv(Poly(2x - 4, x)) (Poly(2x + 4, x, domain='ZZ'), Poly(20, x, domain='ZZ')) """ _, per, F, G = f._unify(g) if hasattr(f.rep, 'pdiv'): q, r = F.pdiv(G) else: # pragma: no cover raise OperationNotSupported(f, 'pdiv') return per(q), per(r) def prem(f, g): """ Polynomial pseudo-remainder of ``f`` by ``g``. Caveat: The function prem(f, g, x) can be safely used to compute in Z[x] _only_ subresultant polynomial remainder sequences (prs's). To safely compute Euclidean and Sturmian prs's in Z[x] employ anyone of the corresponding functions found in the module sympy.polys.subresultants_qq_zz. The functions in the module with suffix _pg compute prs's in Z[x] employing rem(f, g, x), whereas the functions with suffix _amv compute prs's in Z[x] employing rem_z(f, g, x). The function rem_z(f, g, x) differs from prem(f, g, x) in that to compute the remainder polynomials in Z[x] it premultiplies the divident times the absolute value of the leading coefficient of the divisor raised to the power degree(f, x) - degree(g, x) + 1. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x2 + 1, x).prem(Poly(2x - 4, x)) Poly(20, x, domain='ZZ') """ _, per, F, G = f._unify(g) if hasattr(f.rep, 'prem'): result = F.prem(G) else: # pragma: no cover raise OperationNotSupported(f, 'prem') return per(result) def pquo(f, g): """ Polynomial pseudo-quotient of ``f`` by ``g``. See the Caveat note in the function prem(f, g). Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x*2 + 1, x).pquo(Poly(2x - 4, x)) Poly(2x + 4, x, domain='ZZ') >>> Poly(x2 - 1, x).pquo(Poly(2x - 2, x)) Poly(2x + 2, x, domain='ZZ') """ _, per, F, G = f._unify(g) if hasattr(f.rep, 'pquo'): result = F.pquo(G) else: # pragma: no cover raise OperationNotSupported(f, 'pquo') return per(result) def pexquo(f, g): """ Polynomial exact pseudo-quotient of ``f`` by ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x2 - 1, x).pexquo(Poly(2x - 2, x)) Poly(2x + 2, x, domain='ZZ') >>> Poly(x2 + 1, x).pexquo(Poly(2x - 4, x)) Traceback (most recent call last): ... ExactQuotientFailed: 2x - 4 does not divide x2 + 1 """ _, per, F, G = f._unify(g) if hasattr(f.rep, 'pexquo'): try: result = F.pexquo(G) except ExactQuotientFailed as exc: raise exc.new(f.as_expr(), g.as_expr()) else: # pragma: no cover raise OperationNotSupported(f, 'pexquo') return per(result) def div(f, g, auto=True): """ Polynomial division with remainder of ``f`` by ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x2 + 1, x).div(Poly(2x - 4, x)) (Poly(1/2x + 1, x, domain='QQ'), Poly(5, x, domain='QQ')) >>> Poly(x2 + 1, x).div(Poly(2x - 4, x), auto=False) (Poly(0, x, domain='ZZ'), Poly(x2 + 1, x, domain='ZZ')) """ dom, per, F, G = f._unify(g) retract = False if auto and dom.is_Ring and not dom.is_Field: F, G = F.to_field(), G.to_field() retract = True if hasattr(f.rep, 'div'): q, r = F.div(G) else: # pragma: no cover raise OperationNotSupported(f, 'div') if retract: try: Q, R = q.to_ring(), r.to_ring() except CoercionFailed: pass else: q, r = Q, R return per(q), per(r) def rem(f, g, auto=True): """ Computes the polynomial remainder of ``f`` by ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x2 + 1, x).rem(Poly(2x - 4, x)) Poly(5, x, domain='ZZ') >>> Poly(x2 + 1, x).rem(Poly(2x - 4, x), auto=False) Poly(x2 + 1, x, domain='ZZ') """ dom, per, F, G = f._unify(g) retract = False if auto and dom.is_Ring and not dom.is_Field: F, G = F.to_field(), G.to_field() retract = True if hasattr(f.rep, 'rem'): r = F.rem(G) else: # pragma: no cover raise OperationNotSupported(f, 'rem') if retract: try: r = r.to_ring() except CoercionFailed: pass return per(r) def quo(f, g, auto=True): """ Computes polynomial quotient of ``f`` by ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x2 + 1, x).quo(Poly(2x - 4, x)) Poly(1/2x + 1, x, domain='QQ') >>> Poly(x2 - 1, x).quo(Poly(x - 1, x)) Poly(x + 1, x, domain='ZZ') """ dom, per, F, G = f._unify(g) retract = False if auto and dom.is_Ring and not dom.is_Field: F, G = F.to_field(), G.to_field() retract = True if hasattr(f.rep, 'quo'): q = F.quo(G) else: # pragma: no cover raise OperationNotSupported(f, 'quo') if retract: try: q = q.to_ring() except CoercionFailed: pass return per(q) def exquo(f, g, auto=True): """ Computes polynomial exact quotient of ``f`` by ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x2 - 1, x).exquo(Poly(x - 1, x)) Poly(x + 1, x, domain='ZZ') >>> Poly(x*2 + 1, x).exquo(Poly(2x - 4, x)) Traceback (most recent call last): ... ExactQuotientFailed: 2x - 4 does not divide x2 + 1 """ dom, per, F, G = f._unify(g) retract = False if auto and dom.is_Ring and not dom.is_Field: F, G = F.to_field(), G.to_field() retract = True if hasattr(f.rep, 'exquo'): try: q = F.exquo(G) except ExactQuotientFailed as exc: raise exc.new(f.as_expr(), g.as_expr()) else: # pragma: no cover raise OperationNotSupported(f, 'exquo') if retract: try: q = q.to_ring() except CoercionFailed: pass return per(q) def _gen_to_level(f, gen): """Returns level associated with the given generator. """ if isinstance(gen, int): length = len(f.gens) if -length <= gen < length: if gen < 0: return length + gen else: return gen else: raise PolynomialError("-%s <= gen < %s expected, got %s" % (length, length, gen)) else: try: return f.gens.index(sympify(gen)) except ValueError: raise PolynomialError( "a valid generator expected, got %s" % gen) def degree(f, gen=0): """ Returns degree of ``f`` in ``x_j``. The degree of 0 is negative infinity. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x2 + yx + 1, x, y).degree() 2 >>> Poly(x*2 + yx + y, x, y).degree(y) 1 >>> Poly(0, x).degree() -oo """ j = f._gen_to_level(gen) if hasattr(f.rep, 'degree'): return f.rep.degree(j) else: # pragma: no cover raise OperationNotSupported(f, 'degree') def degree_list(f): """ Returns a list of degrees of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x*2 + yx + 1, x, y).degree_list() (2, 1) """ if hasattr(f.rep, 'degree_list'): return f.rep.degree_list() else: # pragma: no cover raise OperationNotSupported(f, 'degree_list') def total_degree(f): """ Returns the total degree of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x*2 + yx + 1, x, y).total_degree() 2 >>> Poly(x + y5, x, y).total_degree() 5 """ if hasattr(f.rep, 'total_degree'): return f.rep.total_degree() else: # pragma: no cover raise OperationNotSupported(f, 'total_degree') def homogenize(f, s): """ Returns the homogeneous polynomial of ``f``. A homogeneous polynomial is a polynomial whose all monomials with non-zero coefficients have the same total degree. If you only want to check if a polynomial is homogeneous, then use :func:`Poly.is_homogeneous`. If you want not only to check if a polynomial is homogeneous but also compute its homogeneous order, then use :func:`Poly.homogeneous_order`. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y, z >>> f = Poly(x5 + 2x2y*2 + 9xy3) >>> f.homogenize(z) Poly(x5 + 2x*2y*2z + 9xy*3z, x, y, z, domain='ZZ') """ if not isinstance(s, Symbol): raise TypeError("``Symbol`` expected, got %s" % type(s)) if s in f.gens: i = f.gens.index(s) gens = f.gens else: i = len(f.gens) gens = f.gens + (s,) if hasattr(f.rep, 'homogenize'): return f.per(f.rep.homogenize(i), gens=gens) raise OperationNotSupported(f, 'homogeneous_order') def homogeneous_order(f): """ Returns the homogeneous order of ``f``. A homogeneous polynomial is a polynomial whose all monomials with non-zero coefficients have the same total degree. This degree is the homogeneous order of ``f``. If you only want to check if a polynomial is homogeneous, then use :func:`Poly.is_homogeneous`. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> f = Poly(x*5 + 2x*3y*2 + 9xy4) >>> f.homogeneous_order() 5 """ if hasattr(f.rep, 'homogeneous_order'): return f.rep.homogeneous_order() else: # pragma: no cover raise OperationNotSupported(f, 'homogeneous_order') def LC(f, order=None): """ Returns the leading coefficient of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(4x*3 + 2x*2 + 3x, x).LC() 4 """ if order is not None: return f.coeffs(order)[0] if hasattr(f.rep, 'LC'): result = f.rep.LC() else: # pragma: no cover raise OperationNotSupported(f, 'LC') return f.rep.dom.to_sympy(result) def TC(f): """ Returns the trailing coefficient of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x*3 + 2x*2 + 3x, x).TC() 0 """ if hasattr(f.rep, 'TC'): result = f.rep.TC() else: # pragma: no cover raise OperationNotSupported(f, 'TC') return f.rep.dom.to_sympy(result) def EC(f, order=None): """ Returns the last non-zero coefficient of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x*3 + 2x*2 + 3x, x).EC() 3 """ if hasattr(f.rep, 'coeffs'): return f.coeffs(order)[-1] else: # pragma: no cover raise OperationNotSupported(f, 'EC') def coeff_monomial(f, monom): """ Returns the coefficient of ``monom`` in ``f`` if there, else None. Examples ======== >>> from sympy import Poly, exp >>> from sympy.abc import x, y >>> p = Poly(24xyexp(8) + 23x, x, y) >>> p.coeff_monomial(x) 23 >>> p.coeff_monomial(y) 0 >>> p.coeff_monomial(xy) 24exp(8) Note that ``Expr.coeff()`` behaves differently, collecting terms if possible; the Poly must be converted to an Expr to use that method, however: >>> p.as_expr().coeff(x) 24yexp(8) + 23 >>> p.as_expr().coeff(y) 24xexp(8) >>> p.as_expr().coeff(xy) 24exp(8) See Also ======== nth: more efficient query using exponents of the monomial's generators """ return f.nth(Monomial(monom, f.gens).exponents) def nth(f, N): """ Returns the ``n``-th coefficient of ``f`` where ``N`` are the exponents of the generators in the term of interest. Examples ======== >>> from sympy import Poly, sqrt >>> from sympy.abc import x, y >>> Poly(x*3 + 2x*2 + 3x, x).nth(2) 2 >>> Poly(x*3 + 2xy2 + y2, x, y).nth(1, 2) 2 >>> Poly(4sqrt(x)y) Poly(4y(sqrt(x)), y, sqrt(x), domain='ZZ') >>> _.nth(1, 1) 4 See Also ======== coeff_monomial """ if hasattr(f.rep, 'nth'): if len(N) != len(f.gens): raise ValueError('exponent of each generator must be specified') result = f.rep.nth(list(map(int, N))) else: # pragma: no cover raise OperationNotSupported(f, 'nth') return f.rep.dom.to_sympy(result) def coeff(f, x, n=1, right=False): # the semantics of coeff_monomial and Expr.coeff are different; # if someone is working with a Poly, they should be aware of the # differences and chose the method best suited for the query. # Alternatively, a pure-polys method could be written here but # at this time the ``right`` keyword would be ignored because Poly # doesn't work with non-commutatives. raise NotImplementedError( 'Either convert to Expr with `as_expr` method ' 'to use Expr\'s coeff method or else use the ' '`coeff_monomial` method of Polys.') def LM(f, order=None): """ Returns the leading monomial of ``f``. The Leading monomial signifies the monomial having the highest power of the principal generator in the expression f. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(4x2 + 2xy2 + xy + 3y, x, y).LM() x2y*0 """ return Monomial(f.monoms(order)[0], f.gens) def EM(f, order=None): """ Returns the last non-zero monomial of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(4x*2 + 2xy2 + xy + 3y, x, y).EM() x0y*1 """ return Monomial(f.monoms(order)[-1], f.gens) def LT(f, order=None): """ Returns the leading term of ``f``. The Leading term signifies the term having the highest power of the principal generator in the expression f along with its coefficient. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(4x*2 + 2xy2 + xy + 3y, x, y).LT() (x2y*0, 4) """ monom, coeff = f.terms(order)[0] return Monomial(monom, f.gens), coeff def ET(f, order=None): """ Returns the last non-zero term of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(4x*2 + 2xy2 + xy + 3y, x, y).ET() (x0y1, 3) """ monom, coeff = f.terms(order)[-1] return Monomial(monom, f.gens), coeff def max_norm(f): """ Returns maximum norm of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(-x2 + 2x - 3, x).max_norm() 3 """ if hasattr(f.rep, 'max_norm'): result = f.rep.max_norm() else: # pragma: no cover raise OperationNotSupported(f, 'max_norm') return f.rep.dom.to_sympy(result) def l1_norm(f): """ Returns l1 norm of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(-x2 + 2x - 3, x).l1_norm() 6 """ if hasattr(f.rep, 'l1_norm'): result = f.rep.l1_norm() else: # pragma: no cover raise OperationNotSupported(f, 'l1_norm') return f.rep.dom.to_sympy(result) def clear_denoms(self, convert=False): """ Clear denominators, but keep the ground domain. Examples ======== >>> from sympy import Poly, S, QQ >>> from sympy.abc import x >>> f = Poly(x/2 + S(1)/3, x, domain=QQ) >>> f.clear_denoms() (6, Poly(3x + 2, x, domain='QQ')) >>> f.clear_denoms(convert=True) (6, Poly(3x + 2, x, domain='ZZ')) """ f = self if not f.rep.dom.is_Field: return S.One, f dom = f.get_domain() if dom.has_assoc_Ring: dom = f.rep.dom.get_ring() if hasattr(f.rep, 'clear_denoms'): coeff, result = f.rep.clear_denoms() else: # pragma: no cover raise OperationNotSupported(f, 'clear_denoms') coeff, f = dom.to_sympy(coeff), f.per(result) if not convert or not dom.has_assoc_Ring: return coeff, f else: return coeff, f.to_ring() def rat_clear_denoms(self, g): """ Clear denominators in a rational function ``f/g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> f = Poly(x2/y + 1, x) >>> g = Poly(x3 + y, x) >>> p, q = f.rat_clear_denoms(g) >>> p Poly(x*2 + y, x, domain='ZZ[y]') >>> q Poly(yx3 + y2, x, domain='ZZ[y]') """ f = self dom, per, f, g = f._unify(g) f = per(f) g = per(g) if not (dom.is_Field and dom.has_assoc_Ring): return f, g a, f = f.clear_denoms(convert=True) b, g = g.clear_denoms(convert=True) f = f.mul_ground(b) g = g.mul_ground(a) return f, g def integrate(self, specs, args): """ Computes indefinite integral of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x2 + 2x + 1, x).integrate() Poly(1/3x3 + x2 + x, x, domain='QQ') >>> Poly(xy*2 + x, x, y).integrate((0, 1), (1, 0)) Poly(1/2x*2y*2 + 1/2x*2, x, y, domain='QQ') """ f = self if args.get('auto', True) and f.rep.dom.is_Ring: f = f.to_field() if hasattr(f.rep, 'integrate'): if not specs: return f.per(f.rep.integrate(m=1)) rep = f.rep for spec in specs: if type(spec) is tuple: gen, m = spec else: gen, m = spec, 1 rep = rep.integrate(int(m), f._gen_to_level(gen)) return f.per(rep) else: # pragma: no cover raise OperationNotSupported(f, 'integrate') def diff(f, specs, kwargs): """ Computes partial derivative of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x2 + 2x + 1, x).diff() Poly(2x + 2, x, domain='ZZ') >>> Poly(xy2 + x, x, y).diff((0, 0), (1, 1)) Poly(2xy, x, y, domain='ZZ') """ if not kwargs.get('evaluate', True): return Derivative(f, specs, kwargs) if hasattr(f.rep, 'diff'): if not specs: return f.per(f.rep.diff(m=1)) rep = f.rep for spec in specs: if type(spec) is tuple: gen, m = spec else: gen, m = spec, 1 rep = rep.diff(int(m), f._gen_to_level(gen)) return f.per(rep) else: # pragma: no cover raise OperationNotSupported(f, 'diff') _eval_derivative = diff def eval(self, x, a=None, auto=True): """ Evaluate ``f`` at ``a`` in the given variable. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y, z >>> Poly(x2 + 2x + 3, x).eval(2) 11 >>> Poly(2xy + 3x + y + 2, x, y).eval(x, 2) Poly(5y + 8, y, domain='ZZ') >>> f = Poly(2xy + 3x + y + 2z, x, y, z) >>> f.eval({x: 2}) Poly(5y + 2z + 6, y, z, domain='ZZ') >>> f.eval({x: 2, y: 5}) Poly(2z + 31, z, domain='ZZ') >>> f.eval({x: 2, y: 5, z: 7}) 45 >>> f.eval((2, 5)) Poly(2z + 31, z, domain='ZZ') >>> f(2, 5) Poly(2z + 31, z, domain='ZZ') """ f = self if a is None: if isinstance(x, dict): mapping = x for gen, value in mapping.items(): f = f.eval(gen, value) return f elif isinstance(x, (tuple, list)): values = x if len(values) > len(f.gens): raise ValueError("too many values provided") for gen, value in zip(f.gens, values): f = f.eval(gen, value) return f else: j, a = 0, x else: j = f._gen_to_level(x) if not hasattr(f.rep, 'eval'): # pragma: no cover raise OperationNotSupported(f, 'eval') try: result = f.rep.eval(a, j) except CoercionFailed: if not auto: raise DomainError("can't evaluate at %s in %s" % (a, f.rep.dom)) else: a_domain, [a] = construct_domain([a]) new_domain = f.get_domain().unify_with_symbols(a_domain, f.gens) f = f.set_domain(new_domain) a = new_domain.convert(a, a_domain) result = f.rep.eval(a, j) return f.per(result, remove=j) def __call__(f, values): """ Evaluate ``f`` at the give values. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y, z >>> f = Poly(2xy + 3x + y + 2z, x, y, z) >>> f(2) Poly(5y + 2z + 6, y, z, domain='ZZ') >>> f(2, 5) Poly(2z + 31, z, domain='ZZ') >>> f(2, 5, 7) 45 """ return f.eval(values) def half_gcdex(f, g, auto=True): """ Half extended Euclidean algorithm of ``f`` and ``g``. Returns ``(s, h)`` such that ``h = gcd(f, g)`` and ``sf = h (mod g)``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> f = x4 - 2x*3 - 6x*2 + 12x + 15 >>> g = x3 + x2 - 4x - 4 >>> Poly(f).half_gcdex(Poly(g)) (Poly(-1/5x + 3/5, x, domain='QQ'), Poly(x + 1, x, domain='QQ')) """ dom, per, F, G = f._unify(g) if auto and dom.is_Ring: F, G = F.to_field(), G.to_field() if hasattr(f.rep, 'half_gcdex'): s, h = F.half_gcdex(G) else: # pragma: no cover raise OperationNotSupported(f, 'half_gcdex') return per(s), per(h) def gcdex(f, g, auto=True): """ Extended Euclidean algorithm of ``f`` and ``g``. Returns ``(s, t, h)`` such that ``h = gcd(f, g)`` and ``sf + tg = h``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> f = x*4 - 2x*3 - 6x*2 + 12x + 15 >>> g = x3 + x2 - 4x - 4 >>> Poly(f).gcdex(Poly(g)) (Poly(-1/5x + 3/5, x, domain='QQ'), Poly(1/5x2 - 6/5x + 2, x, domain='QQ'), Poly(x + 1, x, domain='QQ')) """ dom, per, F, G = f._unify(g) if auto and dom.is_Ring: F, G = F.to_field(), G.to_field() if hasattr(f.rep, 'gcdex'): s, t, h = F.gcdex(G) else: # pragma: no cover raise OperationNotSupported(f, 'gcdex') return per(s), per(t), per(h) def invert(f, g, auto=True): """ Invert ``f`` modulo ``g`` when possible. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x*2 - 1, x).invert(Poly(2x - 1, x)) Poly(-4/3, x, domain='QQ') >>> Poly(x2 - 1, x).invert(Poly(x - 1, x)) Traceback (most recent call last): ... NotInvertible: zero divisor """ dom, per, F, G = f._unify(g) if auto and dom.is_Ring: F, G = F.to_field(), G.to_field() if hasattr(f.rep, 'invert'): result = F.invert(G) else: # pragma: no cover raise OperationNotSupported(f, 'invert') return per(result) def revert(f, n): """ Compute ``f(-1)`` mod ``xn``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(1, x).revert(2) Poly(1, x, domain='ZZ') >>> Poly(1 + x, x).revert(1) Poly(1, x, domain='ZZ') >>> Poly(x2 - 1, x).revert(1) Traceback (most recent call last): ... NotReversible: only unity is reversible in a ring >>> Poly(1/x, x).revert(1) Traceback (most recent call last): ... PolynomialError: 1/x contains an element of the generators set """ if hasattr(f.rep, 'revert'): result = f.rep.revert(int(n)) else: # pragma: no cover raise OperationNotSupported(f, 'revert') return f.per(result) def subresultants(f, g): """ Computes the subresultant PRS of ``f`` and ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x2 + 1, x).subresultants(Poly(x2 - 1, x)) [Poly(x2 + 1, x, domain='ZZ'), Poly(x2 - 1, x, domain='ZZ'), Poly(-2, x, domain='ZZ')] """ _, per, F, G = f._unify(g) if hasattr(f.rep, 'subresultants'): result = F.subresultants(G) else: # pragma: no cover raise OperationNotSupported(f, 'subresultants') return list(map(per, result)) def resultant(f, g, includePRS=False): """ Computes the resultant of ``f`` and ``g`` via PRS. If includePRS=True, it includes the subresultant PRS in the result. Because the PRS is used to calculate the resultant, this is more efficient than calling :func:`subresultants` separately. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> f = Poly(x2 + 1, x) >>> f.resultant(Poly(x2 - 1, x)) 4 >>> f.resultant(Poly(x2 - 1, x), includePRS=True) (4, [Poly(x2 + 1, x, domain='ZZ'), Poly(x2 - 1, x, domain='ZZ'), Poly(-2, x, domain='ZZ')]) """ _, per, F, G = f._unify(g) if hasattr(f.rep, 'resultant'): if includePRS: result, R = F.resultant(G, includePRS=includePRS) else: result = F.resultant(G) else: # pragma: no cover raise OperationNotSupported(f, 'resultant') if includePRS: return (per(result, remove=0), list(map(per, R))) return per(result, remove=0) def discriminant(f): """ Computes the discriminant of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x2 + 2x + 3, x).discriminant() -8 """ if hasattr(f.rep, 'discriminant'): result = f.rep.discriminant() else: # pragma: no cover raise OperationNotSupported(f, 'discriminant') return f.per(result, remove=0) def dispersionset(f, g=None): r"""Compute the dispersion set* of two polynomials. For two polynomials `f(x)` and `g(x)` with `\deg f > 0` and `\deg g > 0` the dispersion set `\operatorname{J}(f, g)` is defined as: .. math:: \operatorname{J}(f, g) & := \{a \in \mathbb{N}_0 \| \gcd(f(x), g(x+a)) \neq 1\} \\ & = \{a \in \mathbb{N}_0 \| \deg \gcd(f(x), g(x+a)) \geq 1\} For a single polynomial one defines `\operatorname{J}(f) := \operatorname{J}(f, f)`. Examples ======== >>> from sympy import poly >>> from sympy.polys.dispersion import dispersion, dispersionset >>> from sympy.abc import x Dispersion set and dispersion of a simple polynomial: >>> fp = poly((x - 3)(x + 3), x) >>> sorted(dispersionset(fp)) [0, 6] >>> dispersion(fp) 6 Note that the definition of the dispersion is not symmetric: >>> fp = poly(x4 - 3x2 + 1, x) >>> gp = fp.shift(-3) >>> sorted(dispersionset(fp, gp)) [2, 3, 4] >>> dispersion(fp, gp) 4 >>> sorted(dispersionset(gp, fp)) [] >>> dispersion(gp, fp) -oo Computing the dispersion also works over field extensions: >>> from sympy import sqrt >>> fp = poly(x2 + sqrt(5)x - 1, x, domain='QQ<sqrt(5)>') >>> gp = poly(x2 + (2 + sqrt(5))x + sqrt(5), x, domain='QQ<sqrt(5)>') >>> sorted(dispersionset(fp, gp)) [2] >>> sorted(dispersionset(gp, fp)) [1, 4] We can even perform the computations for polynomials having symbolic coefficients: >>> from sympy.abc import a >>> fp = poly(4x4 + (4a + 8)x3 + (a2 + 6a + 4)x2 + (a2 + 2a)x, x) >>> sorted(dispersionset(fp)) [0, 1] See Also ======== dispersion References ========== 1. [ManWright94]_ 2. [Koepf98]_ 3. [Abramov71]_ 4. [Man93]_ """ from sympy.polys.dispersion import dispersionset return dispersionset(f, g) def dispersion(f, g=None): r"""Compute the dispersion* of polynomials. For two polynomials `f(x)` and `g(x)` with `\deg f > 0` and `\deg g > 0` the dispersion `\operatorname{dis}(f, g)` is defined as: .. math:: \operatorname{dis}(f, g) & := \max\{ J(f,g) \cup \{0\} \} \\ & = \max\{ \{a \in \mathbb{N} \| \gcd(f(x), g(x+a)) \neq 1\} \cup \{0\} \} and for a single polynomial `\operatorname{dis}(f) := \operatorname{dis}(f, f)`. Examples ======== >>> from sympy import poly >>> from sympy.polys.dispersion import dispersion, dispersionset >>> from sympy.abc import x Dispersion set and dispersion of a simple polynomial: >>> fp = poly((x - 3)(x + 3), x) >>> sorted(dispersionset(fp)) [0, 6] >>> dispersion(fp) 6 Note that the definition of the dispersion is not symmetric: >>> fp = poly(x4 - 3x2 + 1, x) >>> gp = fp.shift(-3) >>> sorted(dispersionset(fp, gp)) [2, 3, 4] >>> dispersion(fp, gp) 4 >>> sorted(dispersionset(gp, fp)) [] >>> dispersion(gp, fp) -oo Computing the dispersion also works over field extensions: >>> from sympy import sqrt >>> fp = poly(x2 + sqrt(5)x - 1, x, domain='QQ<sqrt(5)>') >>> gp = poly(x2 + (2 + sqrt(5))x + sqrt(5), x, domain='QQ<sqrt(5)>') >>> sorted(dispersionset(fp, gp)) [2] >>> sorted(dispersionset(gp, fp)) [1, 4] We can even perform the computations for polynomials having symbolic coefficients: >>> from sympy.abc import a >>> fp = poly(4x4 + (4a + 8)x3 + (a2 + 6a + 4)x2 + (a2 + 2a)x, x) >>> sorted(dispersionset(fp)) [0, 1] See Also ======== dispersionset References ========== 1. [ManWright94]_ 2. [Koepf98]_ 3. [Abramov71]_ 4. [Man93]_ """ from sympy.polys.dispersion import dispersion return dispersion(f, g) def cofactors(f, g): """ Returns the GCD of ``f`` and ``g`` and their cofactors. Returns polynomials ``(h, cff, cfg)`` such that ``h = gcd(f, g)``, and ``cff = quo(f, h)`` and ``cfg = quo(g, h)`` are, so called, cofactors of ``f`` and ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x2 - 1, x).cofactors(Poly(x2 - 3x + 2, x)) (Poly(x - 1, x, domain='ZZ'), Poly(x + 1, x, domain='ZZ'), Poly(x - 2, x, domain='ZZ')) """ _, per, F, G = f._unify(g) if hasattr(f.rep, 'cofactors'): h, cff, cfg = F.cofactors(G) else: # pragma: no cover raise OperationNotSupported(f, 'cofactors') return per(h), per(cff), per(cfg) def gcd(f, g): """ Returns the polynomial GCD of ``f`` and ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x2 - 1, x).gcd(Poly(x2 - 3x + 2, x)) Poly(x - 1, x, domain='ZZ') """ _, per, F, G = f._unify(g) if hasattr(f.rep, 'gcd'): result = F.gcd(G) else: # pragma: no cover raise OperationNotSupported(f, 'gcd') return per(result) def lcm(f, g): """ Returns polynomial LCM of ``f`` and ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x2 - 1, x).lcm(Poly(x2 - 3x + 2, x)) Poly(x*3 - 2x*2 - x + 2, x, domain='ZZ') """ _, per, F, G = f._unify(g) if hasattr(f.rep, 'lcm'): result = F.lcm(G) else: # pragma: no cover raise OperationNotSupported(f, 'lcm') return per(result) def trunc(f, p): """ Reduce ``f`` modulo a constant ``p``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(2x*3 + 3x*2 + 5x + 7, x).trunc(3) Poly(-x*3 - x + 1, x, domain='ZZ') """ p = f.rep.dom.convert(p) if hasattr(f.rep, 'trunc'): result = f.rep.trunc(p) else: # pragma: no cover raise OperationNotSupported(f, 'trunc') return f.per(result) def monic(self, auto=True): """ Divides all coefficients by ``LC(f)``. Examples ======== >>> from sympy import Poly, ZZ >>> from sympy.abc import x >>> Poly(3x*2 + 6x + 9, x, domain=ZZ).monic() Poly(x*2 + 2x + 3, x, domain='QQ') >>> Poly(3x2 + 4x + 2, x, domain=ZZ).monic() Poly(x*2 + 4/3x + 2/3, x, domain='QQ') """ f = self if auto and f.rep.dom.is_Ring: f = f.to_field() if hasattr(f.rep, 'monic'): result = f.rep.monic() else: # pragma: no cover raise OperationNotSupported(f, 'monic') return f.per(result) def content(f): """ Returns the GCD of polynomial coefficients. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(6x2 + 8x + 12, x).content() 2 """ if hasattr(f.rep, 'content'): result = f.rep.content() else: # pragma: no cover raise OperationNotSupported(f, 'content') return f.rep.dom.to_sympy(result) def primitive(f): """ Returns the content and a primitive form of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(2x2 + 8x + 12, x).primitive() (2, Poly(x*2 + 4x + 6, x, domain='ZZ')) """ if hasattr(f.rep, 'primitive'): cont, result = f.rep.primitive() else: # pragma: no cover raise OperationNotSupported(f, 'primitive') return f.rep.dom.to_sympy(cont), f.per(result) def compose(f, g): """ Computes the functional composition of ``f`` and ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x2 + x, x).compose(Poly(x - 1, x)) Poly(x2 - x, x, domain='ZZ') """ _, per, F, G = f._unify(g) if hasattr(f.rep, 'compose'): result = F.compose(G) else: # pragma: no cover raise OperationNotSupported(f, 'compose') return per(result) def decompose(f): """ Computes a functional decomposition of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x*4 + 2x3 - x - 1, x, domain='ZZ').decompose() [Poly(x2 - x - 1, x, domain='ZZ'), Poly(x2 + x, x, domain='ZZ')] """ if hasattr(f.rep, 'decompose'): result = f.rep.decompose() else: # pragma: no cover raise OperationNotSupported(f, 'decompose') return list(map(f.per, result)) def shift(f, a): """ Efficiently compute Taylor shift ``f(x + a)``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x2 - 2x + 1, x).shift(2) Poly(x2 + 2x + 1, x, domain='ZZ') """ if hasattr(f.rep, 'shift'): result = f.rep.shift(a) else: # pragma: no cover raise OperationNotSupported(f, 'shift') return f.per(result) def transform(f, p, q): """ Efficiently evaluate the functional transformation ``q*n f(p/q)``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x*2 - 2x + 1, x).transform(Poly(x + 1, x), Poly(x - 1, x)) Poly(4, x, domain='ZZ') """ P, Q = p.unify(q) F, P = f.unify(P) F, Q = F.unify(Q) if hasattr(F.rep, 'transform'): result = F.rep.transform(P.rep, Q.rep) else: # pragma: no cover raise OperationNotSupported(F, 'transform') return F.per(result) def sturm(self, auto=True): """ Computes the Sturm sequence of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x*3 - 2x2 + x - 3, x).sturm() [Poly(x3 - 2x2 + x - 3, x, domain='QQ'), Poly(3x*2 - 4x + 1, x, domain='QQ'), Poly(2/9x + 25/9, x, domain='QQ'), Poly(-2079/4, x, domain='QQ')] """ f = self if auto and f.rep.dom.is_Ring: f = f.to_field() if hasattr(f.rep, 'sturm'): result = f.rep.sturm() else: # pragma: no cover raise OperationNotSupported(f, 'sturm') return list(map(f.per, result)) def gff_list(f): """ Computes greatest factorial factorization of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> f = x5 + 2x4 - x3 - 2x2 >>> Poly(f).gff_list() [(Poly(x, x, domain='ZZ'), 1), (Poly(x + 2, x, domain='ZZ'), 4)] """ if hasattr(f.rep, 'gff_list'): result = f.rep.gff_list() else: # pragma: no cover raise OperationNotSupported(f, 'gff_list') return [(f.per(g), k) for g, k in result] def norm(f): """ Computes the product, ``Norm(f)``, of the conjugates of a polynomial ``f`` defined over a number field ``K``. Examples ======== >>> from sympy import Poly, sqrt >>> from sympy.abc import x >>> a, b = sqrt(2), sqrt(3) A polynomial over a quadratic extension. Two conjugates x - a and x + a. >>> f = Poly(x - a, x, extension=a) >>> f.norm() Poly(x2 - 2, x, domain='QQ') A polynomial over a quartic extension. Four conjugates x - a, x - a, x + a and x + a. >>> f = Poly(x - a, x, extension=(a, b)) >>> f.norm() Poly(x4 - 4x2 + 4, x, domain='QQ') """ if hasattr(f.rep, 'norm'): r = f.rep.norm() else: # pragma: no cover raise OperationNotSupported(f, 'norm') return f.per(r) def sqf_norm(f): """ Computes square-free norm of ``f``. Returns ``s``, ``f``, ``r``, such that ``g(x) = f(x-sa)`` and ``r(x) = Norm(g(x))`` is a square-free polynomial over ``K``, where ``a`` is the algebraic extension of the ground domain. Examples ======== >>> from sympy import Poly, sqrt >>> from sympy.abc import x >>> s, f, r = Poly(x2 + 1, x, extension=[sqrt(3)]).sqf_norm() >>> s 1 >>> f Poly(x*2 - 2sqrt(3)x + 4, x, domain='QQ<sqrt(3)>') >>> r Poly(x4 - 4x2 + 16, x, domain='QQ') """ if hasattr(f.rep, 'sqf_norm'): s, g, r = f.rep.sqf_norm() else: # pragma: no cover raise OperationNotSupported(f, 'sqf_norm') return s, f.per(g), f.per(r) def sqf_part(f): """ Computes square-free part of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x3 - 3x - 2, x).sqf_part() Poly(x2 - x - 2, x, domain='ZZ') """ if hasattr(f.rep, 'sqf_part'): result = f.rep.sqf_part() else: # pragma: no cover raise OperationNotSupported(f, 'sqf_part') return f.per(result) def sqf_list(f, all=False): """ Returns a list of square-free factors of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> f = 2x*5 + 16x*4 + 50x*3 + 76x*2 + 56x + 16 >>> Poly(f).sqf_list() (2, [(Poly(x + 1, x, domain='ZZ'), 2), (Poly(x + 2, x, domain='ZZ'), 3)]) >>> Poly(f).sqf_list(all=True) (2, [(Poly(1, x, domain='ZZ'), 1), (Poly(x + 1, x, domain='ZZ'), 2), (Poly(x + 2, x, domain='ZZ'), 3)]) """ if hasattr(f.rep, 'sqf_list'): coeff, factors = f.rep.sqf_list(all) else: # pragma: no cover raise OperationNotSupported(f, 'sqf_list') return f.rep.dom.to_sympy(coeff), [(f.per(g), k) for g, k in factors] def sqf_list_include(f, all=False): """ Returns a list of square-free factors of ``f``. Examples ======== >>> from sympy import Poly, expand >>> from sympy.abc import x >>> f = expand(2(x + 1)3x*4) >>> f 2x*7 + 6x*6 + 6x*5 + 2x*4 >>> Poly(f).sqf_list_include() [(Poly(2, x, domain='ZZ'), 1), (Poly(x + 1, x, domain='ZZ'), 3), (Poly(x, x, domain='ZZ'), 4)] >>> Poly(f).sqf_list_include(all=True) [(Poly(2, x, domain='ZZ'), 1), (Poly(1, x, domain='ZZ'), 2), (Poly(x + 1, x, domain='ZZ'), 3), (Poly(x, x, domain='ZZ'), 4)] """ if hasattr(f.rep, 'sqf_list_include'): factors = f.rep.sqf_list_include(all) else: # pragma: no cover raise OperationNotSupported(f, 'sqf_list_include') return [(f.per(g), k) for g, k in factors] def factor_list(f): """ Returns a list of irreducible factors of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> f = 2x*5 + 2x*4y + 4x3 + 4x*2y + 2x + 2y >>> Poly(f).factor_list() (2, [(Poly(x + y, x, y, domain='ZZ'), 1), (Poly(x*2 + 1, x, y, domain='ZZ'), 2)]) """ if hasattr(f.rep, 'factor_list'): try: coeff, factors = f.rep.factor_list() except DomainError: return S.One, [(f, 1)] else: # pragma: no cover raise OperationNotSupported(f, 'factor_list') return f.rep.dom.to_sympy(coeff), [(f.per(g), k) for g, k in factors] def factor_list_include(f): """ Returns a list of irreducible factors of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> f = 2x*5 + 2x*4y + 4x3 + 4x*2y + 2x + 2y >>> Poly(f).factor_list_include() [(Poly(2x + 2y, x, y, domain='ZZ'), 1), (Poly(x2 + 1, x, y, domain='ZZ'), 2)] """ if hasattr(f.rep, 'factor_list_include'): try: factors = f.rep.factor_list_include() except DomainError: return [(f, 1)] else: # pragma: no cover raise OperationNotSupported(f, 'factor_list_include') return [(f.per(g), k) for g, k in factors] def intervals(f, all=False, eps=None, inf=None, sup=None, fast=False, sqf=False): """ Compute isolating intervals for roots of ``f``. For real roots the Vincent-Akritas-Strzebonski (VAS) continued fractions method is used. References ========== .. [#] Alkiviadis G. Akritas and Adam W. Strzebonski: A Comparative Study of Two Real Root Isolation Methods . Nonlinear Analysis: Modelling and Control, Vol. 10, No. 4, 297-304, 2005. .. [#] Alkiviadis G. Akritas, Adam W. Strzebonski and Panagiotis S. Vigklas: Improving the Performance of the Continued Fractions Method Using new Bounds of Positive Roots. Nonlinear Analysis: Modelling and Control, Vol. 13, No. 3, 265-279, 2008. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x2 - 3, x).intervals() [((-2, -1), 1), ((1, 2), 1)] >>> Poly(x*2 - 3, x).intervals(eps=1e-2) [((-26/15, -19/11), 1), ((19/11, 26/15), 1)] """ if eps is not None: eps = QQ.convert(eps) if eps <= 0: raise ValueError("'eps' must be a positive rational") if inf is not None: inf = QQ.convert(inf) if sup is not None: sup = QQ.convert(sup) if hasattr(f.rep, 'intervals'): result = f.rep.intervals( all=all, eps=eps, inf=inf, sup=sup, fast=fast, sqf=sqf) else: # pragma: no cover raise OperationNotSupported(f, 'intervals') if sqf: def _real(interval): s, t = interval return (QQ.to_sympy(s), QQ.to_sympy(t)) if not all: return list(map(_real, result)) def _complex(rectangle): (u, v), (s, t) = rectangle return (QQ.to_sympy(u) + IQQ.to_sympy(v), QQ.to_sympy(s) + IQQ.to_sympy(t)) real_part, complex_part = result return list(map(_real, real_part)), list(map(_complex, complex_part)) else: def _real(interval): (s, t), k = interval return ((QQ.to_sympy(s), QQ.to_sympy(t)), k) if not all: return list(map(_real, result)) def _complex(rectangle): ((u, v), (s, t)), k = rectangle return ((QQ.to_sympy(u) + IQQ.to_sympy(v), QQ.to_sympy(s) + IQQ.to_sympy(t)), k) real_part, complex_part = result return list(map(_real, real_part)), list(map(_complex, complex_part)) def refine_root(f, s, t, eps=None, steps=None, fast=False, check_sqf=False): """ Refine an isolating interval of a root to the given precision. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x2 - 3, x).refine_root(1, 2, eps=1e-2) (19/11, 26/15) """ if check_sqf and not f.is_sqf: raise PolynomialError("only square-free polynomials supported") s, t = QQ.convert(s), QQ.convert(t) if eps is not None: eps = QQ.convert(eps) if eps <= 0: raise ValueError("'eps' must be a positive rational") if steps is not None: steps = int(steps) elif eps is None: steps = 1 if hasattr(f.rep, 'refine_root'): S, T = f.rep.refine_root(s, t, eps=eps, steps=steps, fast=fast) else: # pragma: no cover raise OperationNotSupported(f, 'refine_root') return QQ.to_sympy(S), QQ.to_sympy(T) def count_roots(f, inf=None, sup=None): """ Return the number of roots of ``f`` in ``[inf, sup]`` interval. Examples ======== >>> from sympy import Poly, I >>> from sympy.abc import x >>> Poly(x4 - 4, x).count_roots(-3, 3) 2 >>> Poly(x4 - 4, x).count_roots(0, 1 + 3I) 1 """ inf_real, sup_real = True, True if inf is not None: inf = sympify(inf) if inf is S.NegativeInfinity: inf = None else: re, im = inf.as_real_imag() if not im: inf = QQ.convert(inf) else: inf, inf_real = list(map(QQ.convert, (re, im))), False if sup is not None: sup = sympify(sup) if sup is S.Infinity: sup = None else: re, im = sup.as_real_imag() if not im: sup = QQ.convert(sup) else: sup, sup_real = list(map(QQ.convert, (re, im))), False if inf_real and sup_real: if hasattr(f.rep, 'count_real_roots'): count = f.rep.count_real_roots(inf=inf, sup=sup) else: # pragma: no cover raise OperationNotSupported(f, 'count_real_roots') else: if inf_real and inf is not None: inf = (inf, QQ.zero) if sup_real and sup is not None: sup = (sup, QQ.zero) if hasattr(f.rep, 'count_complex_roots'): count = f.rep.count_complex_roots(inf=inf, sup=sup) else: # pragma: no cover raise OperationNotSupported(f, 'count_complex_roots') return Integer(count) def root(f, index, radicals=True): """ Get an indexed root of a polynomial. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> f = Poly(2x3 - 7x*2 + 4x + 4) >>> f.root(0) -1/2 >>> f.root(1) 2 >>> f.root(2) 2 >>> f.root(3) Traceback (most recent call last): ... IndexError: root index out of [-3, 2] range, got 3 >>> Poly(x5 + x + 1).root(0) CRootOf(x3 - x*2 + 1, 0) """ return sympy.polys.rootoftools.rootof(f, index, radicals=radicals) def real_roots(f, multiple=True, radicals=True): """ Return a list of real roots with multiplicities. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(2x*3 - 7x*2 + 4x + 4).real_roots() [-1/2, 2, 2] >>> Poly(x3 + x + 1).real_roots() [CRootOf(x3 + x + 1, 0)] """ reals = sympy.polys.rootoftools.CRootOf.real_roots(f, radicals=radicals) if multiple: return reals else: return group(reals, multiple=False) def all_roots(f, multiple=True, radicals=True): """ Return a list of real and complex roots with multiplicities. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(2x3 - 7x*2 + 4x + 4).all_roots() [-1/2, 2, 2] >>> Poly(x3 + x + 1).all_roots() [CRootOf(x3 + x + 1, 0), CRootOf(x3 + x + 1, 1), CRootOf(x3 + x + 1, 2)] """ roots = sympy.polys.rootoftools.CRootOf.all_roots(f, radicals=radicals) if multiple: return roots else: return group(roots, multiple=False) def nroots(f, n=15, maxsteps=50, cleanup=True): """ Compute numerical approximations of roots of ``f``. Parameters ========== n ... the number of digits to calculate maxsteps ... the maximum number of iterations to do If the accuracy `n` cannot be reached in `maxsteps`, it will raise an exception. You need to rerun with higher maxsteps. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x2 - 3).nroots(n=15) [-1.73205080756888, 1.73205080756888] >>> Poly(x2 - 3).nroots(n=30) [-1.73205080756887729352744634151, 1.73205080756887729352744634151] """ from sympy.functions.elementary.complexes import sign if f.is_multivariate: raise MultivariatePolynomialError( "can't compute numerical roots of %s" % f) if f.degree() <= 0: return [] # For integer and rational coefficients, convert them to integers only # (for accuracy). Otherwise just try to convert the coefficients to # mpmath.mpc and raise an exception if the conversion fails. if f.rep.dom is ZZ: coeffs = [int(coeff) for coeff in f.all_coeffs()] elif f.rep.dom is QQ: denoms = [coeff.q for coeff in f.all_coeffs()] from sympy.core.numbers import ilcm fac = ilcm(denoms) coeffs = [int(coefffac) for coeff in f.all_coeffs()] else: coeffs = [coeff.evalf(n=n).as_real_imag() for coeff in f.all_coeffs()] try: coeffs = [mpmath.mpc(coeff) for coeff in coeffs] except TypeError: raise DomainError("Numerical domain expected, got %s" % \ f.rep.dom) dps = mpmath.mp.dps mpmath.mp.dps = n try: # We need to add extra precision to guard against losing accuracy. # 10 times the degree of the polynomial seems to work well. roots = mpmath.polyroots(coeffs, maxsteps=maxsteps, cleanup=cleanup, error=False, extraprec=f.degree()10) # Mpmath puts real roots first, then complex ones (as does all_roots) # so we make sure this convention holds here, too. roots = list(map(sympify, sorted(roots, key=lambda r: (1 if r.imag else 0, r.real, abs(r.imag), sign(r.imag))))) except NoConvergence: raise NoConvergence( 'convergence to root failed; try n < %s or maxsteps > %s' % ( n, maxsteps)) finally: mpmath.mp.dps = dps return roots def ground_roots(f): """ Compute roots of ``f`` by factorization in the ground domain. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x*6 - 4x*4 + 4x3 - x2).ground_roots() {0: 2, 1: 2} """ if f.is_multivariate: raise MultivariatePolynomialError( "can't compute ground roots of %s" % f) roots = {} for factor, k in f.factor_list()[1]: if factor.is_linear: a, b = factor.all_coeffs() roots[-b/a] = k return roots def nth_power_roots_poly(f, n): """ Construct a polynomial with n-th powers of roots of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> f = Poly(x4 - x2 + 1) >>> f.nth_power_roots_poly(2) Poly(x*4 - 2x*3 + 3x*2 - 2x + 1, x, domain='ZZ') >>> f.nth_power_roots_poly(3) Poly(x*4 + 2x2 + 1, x, domain='ZZ') >>> f.nth_power_roots_poly(4) Poly(x4 + 2x3 + 3x*2 + 2x + 1, x, domain='ZZ') >>> f.nth_power_roots_poly(12) Poly(x*4 - 4x*3 + 6x*2 - 4x + 1, x, domain='ZZ') """ if f.is_multivariate: raise MultivariatePolynomialError( "must be a univariate polynomial") N = sympify(n) if N.is_Integer and N >= 1: n = int(N) else: raise ValueError("'n' must an integer and n >= 1, got %s" % n) x = f.gen t = Dummy('t') r = f.resultant(f.__class__.from_expr(x*n - t, x, t)) return r.replace(t, x) def cancel(f, g, include=False): """ Cancel common factors in a rational function ``f/g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(2x2 - 2, x).cancel(Poly(x2 - 2x + 1, x)) (1, Poly(2x + 2, x, domain='ZZ'), Poly(x - 1, x, domain='ZZ')) >>> Poly(2x2 - 2, x).cancel(Poly(x2 - 2x + 1, x), include=True) (Poly(2x + 2, x, domain='ZZ'), Poly(x - 1, x, domain='ZZ')) """ dom, per, F, G = f._unify(g) if hasattr(F, 'cancel'): result = F.cancel(G, include=include) else: # pragma: no cover raise OperationNotSupported(f, 'cancel') if not include: if dom.has_assoc_Ring: dom = dom.get_ring() cp, cq, p, q = result cp = dom.to_sympy(cp) cq = dom.to_sympy(cq) return cp/cq, per(p), per(q) else: return tuple(map(per, result)) @property def is_zero(f): """ Returns ``True`` if ``f`` is a zero polynomial. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(0, x).is_zero True >>> Poly(1, x).is_zero False """ return f.rep.is_zero @property def is_one(f): """ Returns ``True`` if ``f`` is a unit polynomial. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(0, x).is_one False >>> Poly(1, x).is_one True """ return f.rep.is_one @property def is_sqf(f): """ Returns ``True`` if ``f`` is a square-free polynomial. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x2 - 2x + 1, x).is_sqf False >>> Poly(x*2 - 1, x).is_sqf True """ return f.rep.is_sqf @property def is_monic(f): """ Returns ``True`` if the leading coefficient of ``f`` is one. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x + 2, x).is_monic True >>> Poly(2x + 2, x).is_monic False """ return f.rep.is_monic @property def is_primitive(f): """ Returns ``True`` if GCD of the coefficients of ``f`` is one. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(2x2 + 6x + 12, x).is_primitive False >>> Poly(x*2 + 3x + 6, x).is_primitive True """ return f.rep.is_primitive @property def is_ground(f): """ Returns ``True`` if ``f`` is an element of the ground domain. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x, x).is_ground False >>> Poly(2, x).is_ground True >>> Poly(y, x).is_ground True """ return f.rep.is_ground @property def is_linear(f): """ Returns ``True`` if ``f`` is linear in all its variables. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x + y + 2, x, y).is_linear True >>> Poly(xy + 2, x, y).is_linear False """ return f.rep.is_linear @property def is_quadratic(f): """ Returns ``True`` if ``f`` is quadratic in all its variables. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(xy + 2, x, y).is_quadratic True >>> Poly(xy2 + 2, x, y).is_quadratic False """ return f.rep.is_quadratic @property def is_monomial(f): """ Returns ``True`` if ``f`` is zero or has only one term. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(3x*2, x).is_monomial True >>> Poly(3x2 + 1, x).is_monomial False """ return f.rep.is_monomial @property def is_homogeneous(f): """ Returns ``True`` if ``f`` is a homogeneous polynomial. A homogeneous polynomial is a polynomial whose all monomials with non-zero coefficients have the same total degree. If you want not only to check if a polynomial is homogeneous but also compute its homogeneous order, then use :func:`Poly.homogeneous_order`. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x2 + xy, x, y).is_homogeneous True >>> Poly(x3 + xy, x, y).is_homogeneous False """ return f.rep.is_homogeneous @property def is_irreducible(f): """ Returns ``True`` if ``f`` has no factors over its domain. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x2 + x + 1, x, modulus=2).is_irreducible True >>> Poly(x2 + 1, x, modulus=2).is_irreducible False """ return f.rep.is_irreducible @property def is_univariate(f): """ Returns ``True`` if ``f`` is a univariate polynomial. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x*2 + x + 1, x).is_univariate True >>> Poly(xy*2 + xy + 1, x, y).is_univariate False >>> Poly(xy2 + xy + 1, x).is_univariate True >>> Poly(x2 + x + 1, x, y).is_univariate False """ return len(f.gens) == 1 @property def is_multivariate(f): """ Returns ``True`` if ``f`` is a multivariate polynomial. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x2 + x + 1, x).is_multivariate False >>> Poly(xy2 + xy + 1, x, y).is_multivariate True >>> Poly(xy2 + xy + 1, x).is_multivariate False >>> Poly(x2 + x + 1, x, y).is_multivariate True """ return len(f.gens) != 1 @property def is_cyclotomic(f): """ Returns ``True`` if ``f`` is a cyclotomic polnomial. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> f = x16 + x14 - x10 + x8 - x6 + x2 + 1 >>> Poly(f).is_cyclotomic False >>> g = x16 + x14 - x10 - x8 - x6 + x*2 + 1 >>> Poly(g).is_cyclotomic True """ return f.rep.is_cyclotomic def __abs__(f): return f.abs() def __neg__(f): return f.neg() @_sympifyit('g', NotImplemented) def __add__(f, g): if not g.is_Poly: try: g = f.__class__(g, f.gens) except PolynomialError: return f.as_expr() + g return f.add(g) @_sympifyit('g', NotImplemented) def __radd__(f, g): if not g.is_Poly: try: g = f.__class__(g, f.gens) except PolynomialError: return g + f.as_expr() return g.add(f) @_sympifyit('g', NotImplemented) def __sub__(f, g): if not g.is_Poly: try: g = f.__class__(g, f.gens) except PolynomialError: return f.as_expr() - g return f.sub(g) @_sympifyit('g', NotImplemented) def __rsub__(f, g): if not g.is_Poly: try: g = f.__class__(g, f.gens) except PolynomialError: return g - f.as_expr() return g.sub(f) @_sympifyit('g', NotImplemented) def __mul__(f, g): if not g.is_Poly: try: g = f.__class__(g, f.gens) except PolynomialError: return f.as_expr()g return f.mul(g) @_sympifyit('g', NotImplemented) def __rmul__(f, g): if not g.is_Poly: try: g = f.__class__(g, f.gens) except PolynomialError: return gf.as_expr() return g.mul(f) @_sympifyit('n', NotImplemented) def __pow__(f, n): if n.is_Integer and n >= 0: return f.pow(n) else: return f.as_expr()n @_sympifyit('g', NotImplemented) def __divmod__(f, g): if not g.is_Poly: g = f.__class__(g, f.gens) return f.div(g) @_sympifyit('g', NotImplemented) def __rdivmod__(f, g): if not g.is_Poly: g = f.__class__(g, f.gens) return g.div(f) @_sympifyit('g', NotImplemented) def __mod__(f, g): if not g.is_Poly: g = f.__class__(g, f.gens) return f.rem(g) @_sympifyit('g', NotImplemented) def __rmod__(f, g): if not g.is_Poly: g = f.__class__(g, f.gens) return g.rem(f) @_sympifyit('g', NotImplemented) def __floordiv__(f, g): if not g.is_Poly: g = f.__class__(g, f.gens) return f.quo(g) @_sympifyit('g', NotImplemented) def __rfloordiv__(f, g): if not g.is_Poly: g = f.__class__(g, f.gens) return g.quo(f) @_sympifyit('g', NotImplemented) def __div__(f, g): return f.as_expr()/g.as_expr() @_sympifyit('g', NotImplemented) def __rdiv__(f, g): return g.as_expr()/f.as_expr() __truediv__ = __div__ __rtruediv__ = __rdiv__ @_sympifyit('other', NotImplemented) def __eq__(self, other): f, g = self, other if not g.is_Poly: try: g = f.__class__(g, f.gens, domain=f.get_domain()) except (PolynomialError, DomainError, CoercionFailed): return False if f.gens != g.gens: return False if f.rep.dom != g.rep.dom: try: dom = f.rep.dom.unify(g.rep.dom, f.gens) except UnificationFailed: return False f = f.set_domain(dom) g = g.set_domain(dom) return f.rep == g.rep @_sympifyit('g', NotImplemented) def __ne__(f, g): return not f == g def __nonzero__(f): return not f.is_zero __bool__ = __nonzero__ def eq(f, g, strict=False): if not strict: return f == g else: return f._strict_eq(sympify(g)) def ne(f, g, strict=False): return not f.eq(g, strict=strict) def _strict_eq(f, g): return isinstance(g, f.__class__) and f.gens == g.gens and f.rep.eq(g.rep, strict=True) @public class PurePoly(Poly): """Class for representing pure polynomials. """ def _hashable_content(self): """Allow SymPy to hash Poly instances. """ return (self.rep,) def __hash__(self): return super(PurePoly, self).__hash__() @property def free_symbols(self): """ Free symbols of a polynomial. Examples ======== >>> from sympy import PurePoly >>> from sympy.abc import x, y >>> PurePoly(x2 + 1).free_symbols set() >>> PurePoly(x2 + y).free_symbols set() >>> PurePoly(x2 + y, x).free_symbols {y} """ return self.free_symbols_in_domain @_sympifyit('other', NotImplemented) def __eq__(self, other): f, g = self, other if not g.is_Poly: try: g = f.__class__(g, f.gens, domain=f.get_domain()) except (PolynomialError, DomainError, CoercionFailed): return False if len(f.gens) != len(g.gens): return False if f.rep.dom != g.rep.dom: try: dom = f.rep.dom.unify(g.rep.dom, f.gens) except UnificationFailed: return False f = f.set_domain(dom) g = g.set_domain(dom) return f.rep == g.rep def _strict_eq(f, g): return isinstance(g, f.__class__) and f.rep.eq(g.rep, strict=True) def _unify(f, g): g = sympify(g) if not g.is_Poly: try: return f.rep.dom, f.per, f.rep, f.rep.per(f.rep.dom.from_sympy(g)) except CoercionFailed: raise UnificationFailed("can't unify %s with %s" % (f, g)) if len(f.gens) != len(g.gens): raise UnificationFailed("can't unify %s with %s" % (f, g)) if not (isinstance(f.rep, DMP) and isinstance(g.rep, DMP)): raise UnificationFailed("can't unify %s with %s" % (f, g)) cls = f.__class__ gens = f.gens dom = f.rep.dom.unify(g.rep.dom, gens) F = f.rep.convert(dom) G = g.rep.convert(dom) def per(rep, dom=dom, gens=gens, remove=None): if remove is not None: gens = gens[:remove] + gens[remove + 1:] if not gens: return dom.to_sympy(rep) return cls.new(rep, gens) return dom, per, F, G @public def poly_from_expr(expr, gens, args): """Construct a polynomial from an expression. """ opt = options.build_options(gens, args) return _poly_from_expr(expr, opt) def _poly_from_expr(expr, opt): """Construct a polynomial from an expression. """ orig, expr = expr, sympify(expr) if not isinstance(expr, Basic): raise PolificationFailed(opt, orig, expr) elif expr.is_Poly: poly = expr.__class__._from_poly(expr, opt) opt.gens = poly.gens opt.domain = poly.domain if opt.polys is None: opt.polys = True return poly, opt elif opt.expand: expr = expr.expand() rep, opt = _dict_from_expr(expr, opt) if not opt.gens: raise PolificationFailed(opt, orig, expr) monoms, coeffs = list(zip(list(rep.items()))) domain = opt.domain if domain is None: opt.domain, coeffs = construct_domain(coeffs, opt=opt) else: coeffs = list(map(domain.from_sympy, coeffs)) rep = dict(list(zip(monoms, coeffs))) poly = Poly._from_dict(rep, opt) if opt.polys is None: opt.polys = False return poly, opt @public def parallel_poly_from_expr(exprs, gens, args): """Construct polynomials from expressions. """ opt = options.build_options(gens, args) return _parallel_poly_from_expr(exprs, opt) def _parallel_poly_from_expr(exprs, opt): """Construct polynomials from expressions. """ from sympy.functions.elementary.piecewise import Piecewise if len(exprs) == 2: f, g = exprs if isinstance(f, Poly) and isinstance(g, Poly): f = f.__class__._from_poly(f, opt) g = g.__class__._from_poly(g, opt) f, g = f.unify(g) opt.gens = f.gens opt.domain = f.domain if opt.polys is None: opt.polys = True return [f, g], opt origs, exprs = list(exprs), [] _exprs, _polys = [], [] failed = False for i, expr in enumerate(origs): expr = sympify(expr) if isinstance(expr, Basic): if expr.is_Poly: _polys.append(i) else: _exprs.append(i) if opt.expand: expr = expr.expand() else: failed = True exprs.append(expr) if failed: raise PolificationFailed(opt, origs, exprs, True) if _polys: # XXX: this is a temporary solution for i in _polys: exprs[i] = exprs[i].as_expr() reps, opt = _parallel_dict_from_expr(exprs, opt) if not opt.gens: raise PolificationFailed(opt, origs, exprs, True) for k in opt.gens: if isinstance(k, Piecewise): raise PolynomialError("Piecewise generators do not make sense") coeffs_list, lengths = [], [] all_monoms = [] all_coeffs = [] for rep in reps: monoms, coeffs = list(zip(list(rep.items()))) coeffs_list.extend(coeffs) all_monoms.append(monoms) lengths.append(len(coeffs)) domain = opt.domain if domain is None: opt.domain, coeffs_list = construct_domain(coeffs_list, opt=opt) else: coeffs_list = list(map(domain.from_sympy, coeffs_list)) for k in lengths: all_coeffs.append(coeffs_list[:k]) coeffs_list = coeffs_list[k:] polys = [] for monoms, coeffs in zip(all_monoms, all_coeffs): rep = dict(list(zip(monoms, coeffs))) poly = Poly._from_dict(rep, opt) polys.append(poly) if opt.polys is None: opt.polys = bool(_polys) return polys, opt def _update_args(args, key, value): """Add a new ``(key, value)`` pair to arguments ``dict``. """ args = dict(args) if key not in args: args[key] = value return args @public def degree(f, gen=0): """ Return the degree of ``f`` in the given variable. The degree of 0 is negative infinity. Examples ======== >>> from sympy import degree >>> from sympy.abc import x, y >>> degree(x*2 + yx + 1, gen=x) 2 >>> degree(x*2 + yx + 1, gen=y) 1 >>> degree(0, x) -oo See also ======== total_degree degree_list """ f = sympify(f, strict=True) gen_is_Num = sympify(gen, strict=True).is_Number if f.is_Poly: p = f isNum = p.as_expr().is_Number else: isNum = f.is_Number if not isNum: if gen_is_Num: p, _ = poly_from_expr(f) else: p, _ = poly_from_expr(f, gen) if isNum: return S.Zero if f else S.NegativeInfinity if not gen_is_Num: if f.is_Poly and gen not in p.gens: # try recast without explicit gens p, _ = poly_from_expr(f.as_expr()) if gen not in p.gens: return S.Zero elif not f.is_Poly and len(f.free_symbols) > 1: raise TypeError(filldedent(''' A symbolic generator of interest is required for a multivariate expression like func = %s, e.g. degree(func, gen = %s) instead of degree(func, gen = %s). ''' % (f, next(ordered(f.free_symbols)), gen))) return Integer(p.degree(gen)) @public def total_degree(f, gens): """ Return the total_degree of ``f`` in the given variables. Examples ======== >>> from sympy import total_degree, Poly >>> from sympy.abc import x, y, z >>> total_degree(1) 0 >>> total_degree(x + xy) 2 >>> total_degree(x + xy, x) 1 If the expression is a Poly and no variables are given then the generators of the Poly will be used: >>> p = Poly(x + xy, y) >>> total_degree(p) 1 To deal with the underlying expression of the Poly, convert it to an Expr: >>> total_degree(p.as_expr()) 2 This is done automatically if any variables are given: >>> total_degree(p, x) 1 See also ======== degree """ p = sympify(f) if p.is_Poly: p = p.as_expr() if p.is_Number: rv = 0 else: if f.is_Poly: gens = gens or f.gens rv = Poly(p, gens).total_degree() return Integer(rv) @public def degree_list(f, gens, args): """ Return a list of degrees of ``f`` in all variables. Examples ======== >>> from sympy import degree_list >>> from sympy.abc import x, y >>> degree_list(x2 + yx + 1) (2, 1) """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, gens, args) except PolificationFailed as exc: raise ComputationFailed('degree_list', 1, exc) degrees = F.degree_list() return tuple(map(Integer, degrees)) @public def LC(f, gens, *args): """ Return the leading coefficient of ``f``. Examples ======== >>> from sympy import LC >>> from sympy.abc import x, y >>> LC(4x*2 + 2xy2 + xy + 3y) 4 """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, gens, *args) except PolificationFailed as exc: raise ComputationFailed('LC', 1, exc) return F.LC(order=opt.order) @public def LM(f, gens, *args): """ Return the leading monomial of ``f``. Examples ======== >>> from sympy import LM >>> from sympy.abc import x, y >>> LM(4x*2 + 2xy2 + xy + 3y) x2 """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, gens, *args) except PolificationFailed as exc: raise ComputationFailed('LM', 1, exc) monom = F.LM(order=opt.order) return monom.as_expr() @public def LT(f, gens, *args): """ Return the leading term of ``f``. Examples ======== >>> from sympy import LT >>> from sympy.abc import x, y >>> LT(4x*2 + 2xy2 + xy + 3y) 4x*2 """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, gens, *args) except PolificationFailed as exc: raise ComputationFailed('LT', 1, exc) monom, coeff = F.LT(order=opt.order) return coeffmonom.as_expr() @public def pdiv(f, g, gens, args): """ Compute polynomial pseudo-division of ``f`` and ``g``. Examples ======== >>> from sympy import pdiv >>> from sympy.abc import x >>> pdiv(x2 + 1, 2x - 4) (2x + 4, 20) """ options.allowed_flags(args, ['polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), gens, *args) except PolificationFailed as exc: raise ComputationFailed('pdiv', 2, exc) q, r = F.pdiv(G) if not opt.polys: return q.as_expr(), r.as_expr() else: return q, r @public def prem(f, g, gens, args): """ Compute polynomial pseudo-remainder of ``f`` and ``g``. Examples ======== >>> from sympy import prem >>> from sympy.abc import x >>> prem(x2 + 1, 2x - 4) 20 """ options.allowed_flags(args, ['polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), gens, *args) except PolificationFailed as exc: raise ComputationFailed('prem', 2, exc) r = F.prem(G) if not opt.polys: return r.as_expr() else: return r @public def pquo(f, g, gens, args): """ Compute polynomial pseudo-quotient of ``f`` and ``g``. Examples ======== >>> from sympy import pquo >>> from sympy.abc import x >>> pquo(x2 + 1, 2x - 4) 2x + 4 >>> pquo(x*2 - 1, 2x - 1) 2x + 1 """ options.allowed_flags(args, ['polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), gens, *args) except PolificationFailed as exc: raise ComputationFailed('pquo', 2, exc) try: q = F.pquo(G) except ExactQuotientFailed: raise ExactQuotientFailed(f, g) if not opt.polys: return q.as_expr() else: return q @public def pexquo(f, g, gens, args): """ Compute polynomial exact pseudo-quotient of ``f`` and ``g``. Examples ======== >>> from sympy import pexquo >>> from sympy.abc import x >>> pexquo(x2 - 1, 2x - 2) 2x + 2 >>> pexquo(x*2 + 1, 2x - 4) Traceback (most recent call last): ... ExactQuotientFailed: 2x - 4 does not divide x2 + 1 """ options.allowed_flags(args, ['polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), gens, *args) except PolificationFailed as exc: raise ComputationFailed('pexquo', 2, exc) q = F.pexquo(G) if not opt.polys: return q.as_expr() else: return q @public def div(f, g, gens, args): """ Compute polynomial division of ``f`` and ``g``. Examples ======== >>> from sympy import div, ZZ, QQ >>> from sympy.abc import x >>> div(x2 + 1, 2x - 4, domain=ZZ) (0, x2 + 1) >>> div(x2 + 1, 2x - 4, domain=QQ) (x/2 + 1, 5) """ options.allowed_flags(args, ['auto', 'polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), gens, args) except PolificationFailed as exc: raise ComputationFailed('div', 2, exc) q, r = F.div(G, auto=opt.auto) if not opt.polys: return q.as_expr(), r.as_expr() else: return q, r @public def rem(f, g, gens, args): """ Compute polynomial remainder of ``f`` and ``g``. Examples ======== >>> from sympy import rem, ZZ, QQ >>> from sympy.abc import x >>> rem(x2 + 1, 2x - 4, domain=ZZ) x2 + 1 >>> rem(x2 + 1, 2x - 4, domain=QQ) 5 """ options.allowed_flags(args, ['auto', 'polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), gens, args) except PolificationFailed as exc: raise ComputationFailed('rem', 2, exc) r = F.rem(G, auto=opt.auto) if not opt.polys: return r.as_expr() else: return r @public def quo(f, g, gens, args): """ Compute polynomial quotient of ``f`` and ``g``. Examples ======== >>> from sympy import quo >>> from sympy.abc import x >>> quo(x2 + 1, 2x - 4) x/2 + 1 >>> quo(x2 - 1, x - 1) x + 1 """ options.allowed_flags(args, ['auto', 'polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), gens, *args) except PolificationFailed as exc: raise ComputationFailed('quo', 2, exc) q = F.quo(G, auto=opt.auto) if not opt.polys: return q.as_expr() else: return q @public def exquo(f, g, gens, args): """ Compute polynomial exact quotient of ``f`` and ``g``. Examples ======== >>> from sympy import exquo >>> from sympy.abc import x >>> exquo(x2 - 1, x - 1) x + 1 >>> exquo(x*2 + 1, 2x - 4) Traceback (most recent call last): ... ExactQuotientFailed: 2x - 4 does not divide x2 + 1 """ options.allowed_flags(args, ['auto', 'polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), gens, *args) except PolificationFailed as exc: raise ComputationFailed('exquo', 2, exc) q = F.exquo(G, auto=opt.auto) if not opt.polys: return q.as_expr() else: return q @public def half_gcdex(f, g, gens, *args): """ Half extended Euclidean algorithm of ``f`` and ``g``. Returns ``(s, h)`` such that ``h = gcd(f, g)`` and ``sf = h (mod g)``. Examples ======== >>> from sympy import half_gcdex >>> from sympy.abc import x >>> half_gcdex(x*4 - 2x*3 - 6x*2 + 12x + 15, x3 + x2 - 4x - 4) (-x/5 + 3/5, x + 1) """ options.allowed_flags(args, ['auto', 'polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), gens, *args) except PolificationFailed as exc: domain, (a, b) = construct_domain(exc.exprs) try: s, h = domain.half_gcdex(a, b) except NotImplementedError: raise ComputationFailed('half_gcdex', 2, exc) else: return domain.to_sympy(s), domain.to_sympy(h) s, h = F.half_gcdex(G, auto=opt.auto) if not opt.polys: return s.as_expr(), h.as_expr() else: return s, h @public def gcdex(f, g, gens, *args): """ Extended Euclidean algorithm of ``f`` and ``g``. Returns ``(s, t, h)`` such that ``h = gcd(f, g)`` and ``sf + tg = h``. Examples ======== >>> from sympy import gcdex >>> from sympy.abc import x >>> gcdex(x4 - 2x*3 - 6x*2 + 12x + 15, x3 + x2 - 4x - 4) (-x/5 + 3/5, x2/5 - 6x/5 + 2, x + 1) """ options.allowed_flags(args, ['auto', 'polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), gens, args) except PolificationFailed as exc: domain, (a, b) = construct_domain(exc.exprs) try: s, t, h = domain.gcdex(a, b) except NotImplementedError: raise ComputationFailed('gcdex', 2, exc) else: return domain.to_sympy(s), domain.to_sympy(t), domain.to_sympy(h) s, t, h = F.gcdex(G, auto=opt.auto) if not opt.polys: return s.as_expr(), t.as_expr(), h.as_expr() else: return s, t, h @public def invert(f, g, gens, args): """ Invert ``f`` modulo ``g`` when possible. Examples ======== >>> from sympy import invert, S >>> from sympy.core.numbers import mod_inverse >>> from sympy.abc import x >>> invert(x2 - 1, 2x - 1) -4/3 >>> invert(x2 - 1, x - 1) Traceback (most recent call last): ... NotInvertible: zero divisor For more efficient inversion of Rationals, use the ``mod_inverse`` function: >>> mod_inverse(3, 5) 2 >>> (S(2)/5).invert(S(7)/3) 5/2 See Also ======== sympy.core.numbers.mod_inverse """ options.allowed_flags(args, ['auto', 'polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), gens, *args) except PolificationFailed as exc: domain, (a, b) = construct_domain(exc.exprs) try: return domain.to_sympy(domain.invert(a, b)) except NotImplementedError: raise ComputationFailed('invert', 2, exc) h = F.invert(G, auto=opt.auto) if not opt.polys: return h.as_expr() else: return h @public def subresultants(f, g, gens, args): """ Compute subresultant PRS of ``f`` and ``g``. Examples ======== >>> from sympy import subresultants >>> from sympy.abc import x >>> subresultants(x2 + 1, x2 - 1) [x2 + 1, x*2 - 1, -2] """ options.allowed_flags(args, ['polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), gens, *args) except PolificationFailed as exc: raise ComputationFailed('subresultants', 2, exc) result = F.subresultants(G) if not opt.polys: return [r.as_expr() for r in result] else: return result @public def resultant(f, g, gens, args): """ Compute resultant of ``f`` and ``g``. Examples ======== >>> from sympy import resultant >>> from sympy.abc import x >>> resultant(x2 + 1, x*2 - 1) 4 """ includePRS = args.pop('includePRS', False) options.allowed_flags(args, ['polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), gens, *args) except PolificationFailed as exc: raise ComputationFailed('resultant', 2, exc) if includePRS: result, R = F.resultant(G, includePRS=includePRS) else: result = F.resultant(G) if not opt.polys: if includePRS: return result.as_expr(), [r.as_expr() for r in R] return result.as_expr() else: if includePRS: return result, R return result @public def discriminant(f, gens, args): """ Compute discriminant of ``f``. Examples ======== >>> from sympy import discriminant >>> from sympy.abc import x >>> discriminant(x2 + 2x + 3) -8 """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, gens, *args) except PolificationFailed as exc: raise ComputationFailed('discriminant', 1, exc) result = F.discriminant() if not opt.polys: return result.as_expr() else: return result @public def cofactors(f, g, gens, args): """ Compute GCD and cofactors of ``f`` and ``g``. Returns polynomials ``(h, cff, cfg)`` such that ``h = gcd(f, g)``, and ``cff = quo(f, h)`` and ``cfg = quo(g, h)`` are, so called, cofactors of ``f`` and ``g``. Examples ======== >>> from sympy import cofactors >>> from sympy.abc import x >>> cofactors(x2 - 1, x*2 - 3x + 2) (x - 1, x + 1, x - 2) """ options.allowed_flags(args, ['polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), gens, args) except PolificationFailed as exc: domain, (a, b) = construct_domain(exc.exprs) try: h, cff, cfg = domain.cofactors(a, b) except NotImplementedError: raise ComputationFailed('cofactors', 2, exc) else: return domain.to_sympy(h), domain.to_sympy(cff), domain.to_sympy(cfg) h, cff, cfg = F.cofactors(G) if not opt.polys: return h.as_expr(), cff.as_expr(), cfg.as_expr() else: return h, cff, cfg @public def gcd_list(seq, gens, args): """ Compute GCD of a list of polynomials. Examples ======== >>> from sympy import gcd_list >>> from sympy.abc import x >>> gcd_list([x3 - 1, x2 - 1, x2 - 3x + 2]) x - 1 """ seq = sympify(seq) def try_non_polynomial_gcd(seq): if not gens and not args: domain, numbers = construct_domain(seq) if not numbers: return domain.zero elif domain.is_Numerical: result, numbers = numbers[0], numbers[1:] for number in numbers: result = domain.gcd(result, number) if domain.is_one(result): break return domain.to_sympy(result) return None result = try_non_polynomial_gcd(seq) if result is not None: return result options.allowed_flags(args, ['polys']) try: polys, opt = parallel_poly_from_expr(seq, gens, *args) # gcd for domain Q[irrational] (purely algebraic irrational) if len(seq) > 1 and all(elt.is_algebraic and elt.is_irrational for elt in seq): a = seq[-1] lst = [ (a/elt).ratsimp() for elt in seq[:-1] ] if all(frc.is_rational for frc in lst): lc = 1 for frc in lst: lc = lcm(lc, frc.as_numer_denom()[0]) return a/lc except PolificationFailed as exc: result = try_non_polynomial_gcd(exc.exprs) if result is not None: return result else: raise ComputationFailed('gcd_list', len(seq), exc) if not polys: if not opt.polys: return S.Zero else: return Poly(0, opt=opt) result, polys = polys[0], polys[1:] for poly in polys: result = result.gcd(poly) if result.is_one: break if not opt.polys: return result.as_expr() else: return result @public def gcd(f, g=None, gens, args): """ Compute GCD of ``f`` and ``g``. Examples ======== >>> from sympy import gcd >>> from sympy.abc import x >>> gcd(x2 - 1, x*2 - 3x + 2) x - 1 """ if hasattr(f, '__iter__'): if g is not None: gens = (g,) + gens return gcd_list(f, gens, args) elif g is None: raise TypeError("gcd() takes 2 arguments or a sequence of arguments") options.allowed_flags(args, ['polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), gens, *args) # gcd for domain Q[irrational] (purely algebraic irrational) a, b = map(sympify, (f, g)) if a.is_algebraic and a.is_irrational and b.is_algebraic and b.is_irrational: frc = (a/b).ratsimp() if frc.is_rational: return a/frc.as_numer_denom()[0] except PolificationFailed as exc: domain, (a, b) = construct_domain(exc.exprs) try: return domain.to_sympy(domain.gcd(a, b)) except NotImplementedError: raise ComputationFailed('gcd', 2, exc) result = F.gcd(G) if not opt.polys: return result.as_expr() else: return result @public def lcm_list(seq, gens, args): """ Compute LCM of a list of polynomials. Examples ======== >>> from sympy import lcm_list >>> from sympy.abc import x >>> lcm_list([x3 - 1, x2 - 1, x2 - 3x + 2]) x5 - x4 - 2x3 - x2 + x + 2 """ seq = sympify(seq) def try_non_polynomial_lcm(seq): if not gens and not args: domain, numbers = construct_domain(seq) if not numbers: return domain.one elif domain.is_Numerical: result, numbers = numbers[0], numbers[1:] for number in numbers: result = domain.lcm(result, number) return domain.to_sympy(result) return None result = try_non_polynomial_lcm(seq) if result is not None: return result options.allowed_flags(args, ['polys']) try: polys, opt = parallel_poly_from_expr(seq, gens, args) # lcm for domain Q[irrational] (purely algebraic irrational) if len(seq) > 1 and all(elt.is_algebraic and elt.is_irrational for elt in seq): a = seq[-1] lst = [ (a/elt).ratsimp() for elt in seq[:-1] ] if all(frc.is_rational for frc in lst): lc = 1 for frc in lst: lc = lcm(lc, frc.as_numer_denom()[1]) return alc except PolificationFailed as exc: result = try_non_polynomial_lcm(exc.exprs) if result is not None: return result else: raise ComputationFailed('lcm_list', len(seq), exc) if not polys: if not opt.polys: return S.One else: return Poly(1, opt=opt) result, polys = polys[0], polys[1:] for poly in polys: result = result.lcm(poly) if not opt.polys: return result.as_expr() else: return result @public def lcm(f, g=None, gens, args): """ Compute LCM of ``f`` and ``g``. Examples ======== >>> from sympy import lcm >>> from sympy.abc import x >>> lcm(x2 - 1, x2 - 3x + 2) x*3 - 2x*2 - x + 2 """ if hasattr(f, '__iter__'): if g is not None: gens = (g,) + gens return lcm_list(f, gens, *args) elif g is None: raise TypeError("lcm() takes 2 arguments or a sequence of arguments") options.allowed_flags(args, ['polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), gens, *args) # lcm for domain Q[irrational] (purely algebraic irrational) a, b = map(sympify, (f, g)) if a.is_algebraic and a.is_irrational and b.is_algebraic and b.is_irrational: frc = (a/b).ratsimp() if frc.is_rational: return afrc.as_numer_denom()[1] except PolificationFailed as exc: domain, (a, b) = construct_domain(exc.exprs) try: return domain.to_sympy(domain.lcm(a, b)) except NotImplementedError: raise ComputationFailed('lcm', 2, exc) result = F.lcm(G) if not opt.polys: return result.as_expr() else: return result @public def terms_gcd(f, gens, args): """ Remove GCD of terms from ``f``. If the ``deep`` flag is True, then the arguments of ``f`` will have terms_gcd applied to them. If a fraction is factored out of ``f`` and ``f`` is an Add, then an unevaluated Mul will be returned so that automatic simplification does not redistribute it. The hint ``clear``, when set to False, can be used to prevent such factoring when all coefficients are not fractions. Examples ======== >>> from sympy import terms_gcd, cos >>> from sympy.abc import x, y >>> terms_gcd(x6y2 + x3y, x, y) x3y(x3y + 1) The default action of polys routines is to expand the expression given to them. terms_gcd follows this behavior: >>> terms_gcd((3+3x)(x+xy)) 3x(xy + x + y + 1) If this is not desired then the hint ``expand`` can be set to False. In this case the expression will be treated as though it were comprised of one or more terms: >>> terms_gcd((3+3x)(x+xy), expand=False) (3x + 3)(xy + x) In order to traverse factors of a Mul or the arguments of other functions, the ``deep`` hint can be used: >>> terms_gcd((3 + 3x)(x + xy), expand=False, deep=True) 3x(x + 1)(y + 1) >>> terms_gcd(cos(x + xy), deep=True) cos(x(y + 1)) Rationals are factored out by default: >>> terms_gcd(x + y/2) (2x + y)/2 Only the y-term had a coefficient that was a fraction; if one does not want to factor out the 1/2 in cases like this, the flag ``clear`` can be set to False: >>> terms_gcd(x + y/2, clear=False) x + y/2 >>> terms_gcd(xy/2 + y*2, clear=False) y(x/2 + y) The ``clear`` flag is ignored if all coefficients are fractions: >>> terms_gcd(x/3 + y/2, clear=False) (2x + 3y)/6 See Also ======== sympy.core.exprtools.gcd_terms, sympy.core.exprtools.factor_terms """ from sympy.core.relational import Equality orig = sympify(f) if not isinstance(f, Expr) or f.is_Atom: return orig if args.get('deep', False): new = f.func([terms_gcd(a, gens, *args) for a in f.args]) args.pop('deep') args['expand'] = False return terms_gcd(new, gens, *args) if isinstance(f, Equality): return f clear = args.pop('clear', True) options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, gens, *args) except PolificationFailed as exc: return exc.expr J, f = F.terms_gcd() if opt.domain.is_Ring: if opt.domain.is_Field: denom, f = f.clear_denoms(convert=True) coeff, f = f.primitive() if opt.domain.is_Field: coeff /= denom else: coeff = S.One term = Mul([x*j for x, j in zip(f.gens, J)]) if coeff == 1: coeff = S.One if term == 1: return orig if clear: return _keep_coeff(coeff, termf.as_expr()) # base the clearing on the form of the original expression, not # the (perhaps) Mul that we have now coeff, f = _keep_coeff(coeff, f.as_expr(), clear=False).as_coeff_Mul() return _keep_coeff(coeff, termf, clear=False) @public def trunc(f, p, gens, *args): """ Reduce ``f`` modulo a constant ``p``. Examples ======== >>> from sympy import trunc >>> from sympy.abc import x >>> trunc(2x*3 + 3x*2 + 5x + 7, 3) -x*3 - x + 1 """ options.allowed_flags(args, ['auto', 'polys']) try: F, opt = poly_from_expr(f, gens, *args) except PolificationFailed as exc: raise ComputationFailed('trunc', 1, exc) result = F.trunc(sympify(p)) if not opt.polys: return result.as_expr() else: return result @public def monic(f, gens, *args): """ Divide all coefficients of ``f`` by ``LC(f)``. Examples ======== >>> from sympy import monic >>> from sympy.abc import x >>> monic(3x*2 + 4x + 2) x*2 + 4x/3 + 2/3 """ options.allowed_flags(args, ['auto', 'polys']) try: F, opt = poly_from_expr(f, gens, args) except PolificationFailed as exc: raise ComputationFailed('monic', 1, exc) result = F.monic(auto=opt.auto) if not opt.polys: return result.as_expr() else: return result @public def content(f, gens, *args): """ Compute GCD of coefficients of ``f``. Examples ======== >>> from sympy import content >>> from sympy.abc import x >>> content(6x*2 + 8x + 12) 2 """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, gens, args) except PolificationFailed as exc: raise ComputationFailed('content', 1, exc) return F.content() @public def primitive(f, gens, *args): """ Compute content and the primitive form of ``f``. Examples ======== >>> from sympy.polys.polytools import primitive >>> from sympy.abc import x >>> primitive(6x*2 + 8x + 12) (2, 3x2 + 4x + 6) >>> eq = (2 + 2x)x + 2 Expansion is performed by default: >>> primitive(eq) (2, x*2 + x + 1) Set ``expand`` to False to shut this off. Note that the extraction will not be recursive; use the as_content_primitive method for recursive, non-destructive Rational extraction. >>> primitive(eq, expand=False) (1, x(2x + 2) + 2) >>> eq.as_content_primitive() (2, x(x + 1) + 1) """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, gens, args) except PolificationFailed as exc: raise ComputationFailed('primitive', 1, exc) cont, result = F.primitive() if not opt.polys: return cont, result.as_expr() else: return cont, result @public def compose(f, g, gens, args): """ Compute functional composition ``f(g)``. Examples ======== >>> from sympy import compose >>> from sympy.abc import x >>> compose(x2 + x, x - 1) x*2 - x """ options.allowed_flags(args, ['polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), gens, *args) except PolificationFailed as exc: raise ComputationFailed('compose', 2, exc) result = F.compose(G) if not opt.polys: return result.as_expr() else: return result @public def decompose(f, gens, args): """ Compute functional decomposition of ``f``. Examples ======== >>> from sympy import decompose >>> from sympy.abc import x >>> decompose(x4 + 2x3 - x - 1) [x2 - x - 1, x2 + x] """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, gens, *args) except PolificationFailed as exc: raise ComputationFailed('decompose', 1, exc) result = F.decompose() if not opt.polys: return [r.as_expr() for r in result] else: return result @public def sturm(f, gens, args): """ Compute Sturm sequence of ``f``. Examples ======== >>> from sympy import sturm >>> from sympy.abc import x >>> sturm(x3 - 2x2 + x - 3) [x3 - 2x*2 + x - 3, 3x*2 - 4x + 1, 2x/9 + 25/9, -2079/4] """ options.allowed_flags(args, ['auto', 'polys']) try: F, opt = poly_from_expr(f, gens, *args) except PolificationFailed as exc: raise ComputationFailed('sturm', 1, exc) result = F.sturm(auto=opt.auto) if not opt.polys: return [r.as_expr() for r in result] else: return result @public def gff_list(f, gens, args): """ Compute a list of greatest factorial factors of ``f``. Note that the input to ff() and rf() should be Poly instances to use the definitions here. Examples ======== >>> from sympy import gff_list, ff, Poly >>> from sympy.abc import x >>> f = Poly(x5 + 2x4 - x3 - 2x*2, x) >>> gff_list(f) [(Poly(x, x, domain='ZZ'), 1), (Poly(x + 2, x, domain='ZZ'), 4)] >>> (ff(Poly(x), 1)ff(Poly(x + 2), 4)).expand() == f True >>> f = Poly(x*12 + 6x*11 - 11x*10 - 56x*9 + 220x*8 + 208x*7 - \ 1401x*6 + 1090x*5 + 2715x*4 - 6720x*3 - 1092x*2 + 5040x, x) >>> gff_list(f) [(Poly(x3 + 7, x, domain='ZZ'), 2), (Poly(x2 + 5x, x, domain='ZZ'), 3)] >>> ff(Poly(x3 + 7, x), 2)ff(Poly(x*2 + 5x, x), 3) == f True """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, gens, args) except PolificationFailed as exc: raise ComputationFailed('gff_list', 1, exc) factors = F.gff_list() if not opt.polys: return [(g.as_expr(), k) for g, k in factors] else: return factors @public def gff(f, gens, *args): """Compute greatest factorial factorization of ``f``. """ raise NotImplementedError('symbolic falling factorial') @public def sqf_norm(f, gens, args): """ Compute square-free norm of ``f``. Returns ``s``, ``f``, ``r``, such that ``g(x) = f(x-sa)`` and ``r(x) = Norm(g(x))`` is a square-free polynomial over ``K``, where ``a`` is the algebraic extension of the ground domain. Examples ======== >>> from sympy import sqf_norm, sqrt >>> from sympy.abc import x >>> sqf_norm(x2 + 1, extension=[sqrt(3)]) (1, x*2 - 2sqrt(3)x + 4, x4 - 4x*2 + 16) """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, gens, *args) except PolificationFailed as exc: raise ComputationFailed('sqf_norm', 1, exc) s, g, r = F.sqf_norm() if not opt.polys: return Integer(s), g.as_expr(), r.as_expr() else: return Integer(s), g, r @public def sqf_part(f, gens, args): """ Compute square-free part of ``f``. Examples ======== >>> from sympy import sqf_part >>> from sympy.abc import x >>> sqf_part(x3 - 3x - 2) x2 - x - 2 """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, gens, *args) except PolificationFailed as exc: raise ComputationFailed('sqf_part', 1, exc) result = F.sqf_part() if not opt.polys: return result.as_expr() else: return result def _sorted_factors(factors, method): """Sort a list of ``(expr, exp)`` pairs. """ if method == 'sqf': def key(obj): poly, exp = obj rep = poly.rep.rep return (exp, len(rep), len(poly.gens), rep) else: def key(obj): poly, exp = obj rep = poly.rep.rep return (len(rep), len(poly.gens), exp, rep) return sorted(factors, key=key) def _factors_product(factors): """Multiply a list of ``(expr, exp)`` pairs. """ return Mul([f.as_expr()*k for f, k in factors]) def _symbolic_factor_list(expr, opt, method): """Helper function for :func:`_symbolic_factor`. """ coeff, factors = S.One, [] args = [i._eval_factor() if hasattr(i, '_eval_factor') else i for i in Mul.make_args(expr)] for arg in args: if arg.is_Number: coeff = arg continue if arg.is_Mul: args.extend(arg.args) continue if arg.is_Pow: base, exp = arg.args if base.is_Number and exp.is_Number: coeff = arg continue if base.is_Number: factors.append((base, exp)) continue else: base, exp = arg, S.One try: poly, _ = _poly_from_expr(base, opt) except PolificationFailed as exc: factors.append((exc.expr, exp)) else: func = getattr(poly, method + '_list') _coeff, _factors = func() if _coeff is not S.One: if exp.is_Integer: coeff = _coeff*exp elif _coeff.is_positive: factors.append((_coeff, exp)) else: _factors.append((_coeff, S.One)) if exp is S.One: factors.extend(_factors) elif exp.is_integer: factors.extend([(f, kexp) for f, k in _factors]) else: other = [] for f, k in _factors: if f.as_expr().is_positive: factors.append((f, kexp)) else: other.append((f, k)) factors.append((_factors_product(other), exp)) return coeff, factors def _symbolic_factor(expr, opt, method): """Helper function for :func:`_factor`. """ if isinstance(expr, Expr) and not expr.is_Relational: if hasattr(expr,'_eval_factor'): return expr._eval_factor() coeff, factors = _symbolic_factor_list(together(expr), opt, method) return _keep_coeff(coeff, _factors_product(factors)) elif hasattr(expr, 'args'): return expr.func([_symbolic_factor(arg, opt, method) for arg in expr.args]) elif hasattr(expr, '__iter__'): return expr.__class__([_symbolic_factor(arg, opt, method) for arg in expr]) else: return expr def _generic_factor_list(expr, gens, args, method): """Helper function for :func:`sqf_list` and :func:`factor_list`. """ options.allowed_flags(args, ['frac', 'polys']) opt = options.build_options(gens, args) expr = sympify(expr) if isinstance(expr, Expr) and not expr.is_Relational: numer, denom = together(expr).as_numer_denom() cp, fp = _symbolic_factor_list(numer, opt, method) cq, fq = _symbolic_factor_list(denom, opt, method) if fq and not opt.frac: raise PolynomialError("a polynomial expected, got %s" % expr) _opt = opt.clone(dict(expand=True)) for factors in (fp, fq): for i, (f, k) in enumerate(factors): if not f.is_Poly: f, _ = _poly_from_expr(f, _opt) factors[i] = (f, k) fp = _sorted_factors(fp, method) fq = _sorted_factors(fq, method) if not opt.polys: fp = [(f.as_expr(), k) for f, k in fp] fq = [(f.as_expr(), k) for f, k in fq] coeff = cp/cq if not opt.frac: return coeff, fp else: return coeff, fp, fq else: raise PolynomialError("a polynomial expected, got %s" % expr) def _generic_factor(expr, gens, args, method): """Helper function for :func:`sqf` and :func:`factor`. """ options.allowed_flags(args, []) opt = options.build_options(gens, args) return _symbolic_factor(sympify(expr), opt, method) def to_rational_coeffs(f): """ try to transform a polynomial to have rational coefficients try to find a transformation ``x = alphay`` ``f(x) = lcalpha*n g(y)`` where ``g`` is a polynomial with rational coefficients, ``lc`` the leading coefficient. If this fails, try ``x = y + beta`` ``f(x) = g(y)`` Returns ``None`` if ``g`` not found; ``(lc, alpha, None, g)`` in case of rescaling ``(None, None, beta, g)`` in case of translation Notes ===== Currently it transforms only polynomials without roots larger than 2. Examples ======== >>> from sympy import sqrt, Poly, simplify >>> from sympy.polys.polytools import to_rational_coeffs >>> from sympy.abc import x >>> p = Poly(((x*2-1)(x-2)).subs({x:x(1 + sqrt(2))}), x, domain='EX') >>> lc, r, _, g = to_rational_coeffs(p) >>> lc, r (7 + 5sqrt(2), -2sqrt(2) + 2) >>> g Poly(x3 + x2 - 1/4x - 1/4, x, domain='QQ') >>> r1 = simplify(1/r) >>> Poly(lcr3(g.as_expr()).subs({x:xr1}), x, domain='EX') == p True """ from sympy.simplify.simplify import simplify def _try_rescale(f, f1=None): """ try rescaling ``x -> alphax`` to convert f to a polynomial with rational coefficients. Returns ``alpha, f``; if the rescaling is successful, ``alpha`` is the rescaling factor, and ``f`` is the rescaled polynomial; else ``alpha`` is ``None``. """ from sympy.core.add import Add if not len(f.gens) == 1 or not (f.gens[0]).is_Atom: return None, f n = f.degree() lc = f.LC() f1 = f1 or f1.monic() coeffs = f1.all_coeffs()[1:] coeffs = [simplify(coeffx) for coeffx in coeffs] if coeffs[-2]: rescale1_x = simplify(coeffs[-2]/coeffs[-1]) coeffs1 = [] for i in range(len(coeffs)): coeffx = simplify(coeffs[i]rescale1_x(i + 1)) if not coeffx.is_rational: break coeffs1.append(coeffx) else: rescale_x = simplify(1/rescale1_x) x = f.gens[0] v = [xn] for i in range(1, n + 1): v.append(coeffs1[i - 1]x*(n - i)) f = Add(v) f = Poly(f) return lc, rescale_x, f return None def _try_translate(f, f1=None): """ try translating ``x -> x + alpha`` to convert f to a polynomial with rational coefficients. Returns ``alpha, f``; if the translating is successful, ``alpha`` is the translating factor, and ``f`` is the shifted polynomial; else ``alpha`` is ``None``. """ from sympy.core.add import Add if not len(f.gens) == 1 or not (f.gens[0]).is_Atom: return None, f n = f.degree() f1 = f1 or f1.monic() coeffs = f1.all_coeffs()[1:] c = simplify(coeffs[0]) if c and not c.is_rational: func = Add if c.is_Add: args = c.args func = c.func else: args = [c] c1, c2 = sift(args, lambda z: z.is_rational, binary=True) alpha = -func(c2)/n f2 = f1.shift(alpha) return alpha, f2 return None def _has_square_roots(p): """ Return True if ``f`` is a sum with square roots but no other root """ from sympy.core.exprtools import Factors coeffs = p.coeffs() has_sq = False for y in coeffs: for x in Add.make_args(y): f = Factors(x).factors r = [wx.q for b, wx in f.items() if b.is_number and wx.is_Rational and wx.q >= 2] if not r: continue if min(r) == 2: has_sq = True if max(r) > 2: return False return has_sq if f.get_domain().is_EX and _has_square_roots(f): f1 = f.monic() r = _try_rescale(f, f1) if r: return r[0], r[1], None, r[2] else: r = _try_translate(f, f1) if r: return None, None, r[0], r[1] return None def _torational_factor_list(p, x): """ helper function to factor polynomial using to_rational_coeffs Examples ======== >>> from sympy.polys.polytools import _torational_factor_list >>> from sympy.abc import x >>> from sympy import sqrt, expand, Mul >>> p = expand(((x2-1)(x-2)).subs({x:x(1 + sqrt(2))})) >>> factors = _torational_factor_list(p, x); factors (-2, [(-x(1 + sqrt(2))/2 + 1, 1), (-x(1 + sqrt(2)) - 1, 1), (-x(1 + sqrt(2)) + 1, 1)]) >>> expand(factors[0]Mul([z[0] for z in factors[1]])) == p True >>> p = expand(((x*2-1)(x-2)).subs({x:x + sqrt(2)})) >>> factors = _torational_factor_list(p, x); factors (1, [(x - 2 + sqrt(2), 1), (x - 1 + sqrt(2), 1), (x + 1 + sqrt(2), 1)]) >>> expand(factors[0]Mul([z[0] for z in factors[1]])) == p True """ from sympy.simplify.simplify import simplify p1 = Poly(p, x, domain='EX') n = p1.degree() res = to_rational_coeffs(p1) if not res: return None lc, r, t, g = res factors = factor_list(g.as_expr()) if lc: c = simplify(factors[0]lcr*n) r1 = simplify(1/r) a = [] for z in factors[1:][0]: a.append((simplify(z[0].subs({x: xr1})), z[1])) else: c = factors[0] a = [] for z in factors[1:][0]: a.append((z[0].subs({x: x - t}), z[1])) return (c, a) @public def sqf_list(f, gens, args): """ Compute a list of square-free factors of ``f``. Examples ======== >>> from sympy import sqf_list >>> from sympy.abc import x >>> sqf_list(2x*5 + 16x*4 + 50x*3 + 76x*2 + 56x + 16) (2, [(x + 1, 2), (x + 2, 3)]) """ return _generic_factor_list(f, gens, args, method='sqf') @public def sqf(f, gens, args): """ Compute square-free factorization of ``f``. Examples ======== >>> from sympy import sqf >>> from sympy.abc import x >>> sqf(2x*5 + 16x*4 + 50x*3 + 76x*2 + 56x + 16) 2(x + 1)2(x + 2)*3 """ return _generic_factor(f, gens, args, method='sqf') @public def factor_list(f, gens, *args): """ Compute a list of irreducible factors of ``f``. Examples ======== >>> from sympy import factor_list >>> from sympy.abc import x, y >>> factor_list(2x*5 + 2x*4y + 4x3 + 4x*2y + 2x + 2y) (2, [(x + y, 1), (x*2 + 1, 2)]) """ return _generic_factor_list(f, gens, args, method='factor') @public def factor(f, gens, *args): """ Compute the factorization of expression, ``f``, into irreducibles. (To factor an integer into primes, use ``factorint``.) There two modes implemented: symbolic and formal. If ``f`` is not an instance of :class:`Poly` and generators are not specified, then the former mode is used. Otherwise, the formal mode is used. In symbolic mode, :func:`factor` will traverse the expression tree and factor its components without any prior expansion, unless an instance of :class:`Add` is encountered (in this case formal factorization is used). This way :func:`factor` can handle large or symbolic exponents. By default, the factorization is computed over the rationals. To factor over other domain, e.g. an algebraic or finite field, use appropriate options: ``extension``, ``modulus`` or ``domain``. Examples ======== >>> from sympy import factor, sqrt >>> from sympy.abc import x, y >>> factor(2x*5 + 2x*4y + 4x3 + 4x*2y + 2x + 2y) 2(x + y)(x2 + 1)2 >>> factor(x2 + 1) x2 + 1 >>> factor(x2 + 1, modulus=2) (x + 1)2 >>> factor(x*2 + 1, gaussian=True) (x - I)(x + I) >>> factor(x*2 - 2, extension=sqrt(2)) (x - sqrt(2))(x + sqrt(2)) >>> factor((x2 - 1)/(x2 + 4x + 4)) (x - 1)(x + 1)/(x + 2)2 >>> factor((x2 + 4x + 4)10000000(x2 + 1)) (x + 2)20000000(x2 + 1) By default, factor deals with an expression as a whole: >>> eq = 2(x2 + 2x + 1) >>> factor(eq) 2(x2 + 2x + 1) If the ``deep`` flag is True then subexpressions will be factored: >>> factor(eq, deep=True) 2((x + 1)2) See Also ======== sympy.ntheory.factor_.factorint """ f = sympify(f) if args.pop('deep', False): from sympy.simplify.simplify import bottom_up def _try_factor(expr): """ Factor, but avoid changing the expression when unable to. """ fac = factor(expr) if fac.is_Mul or fac.is_Pow: return fac return expr f = bottom_up(f, _try_factor) # clean up any subexpressions that may have been expanded # while factoring out a larger expression partials = {} muladd = f.atoms(Mul, Add) for p in muladd: fac = factor(p, gens, args) if (fac.is_Mul or fac.is_Pow) and fac != p: partials[p] = fac return f.xreplace(partials) try: return _generic_factor(f, gens, args, method='factor') except PolynomialError as msg: if not f.is_commutative: from sympy.core.exprtools import factor_nc return factor_nc(f) else: raise PolynomialError(msg) @public def intervals(F, all=False, eps=None, inf=None, sup=None, strict=False, fast=False, sqf=False): """ Compute isolating intervals for roots of ``f``. Examples ======== >>> from sympy import intervals >>> from sympy.abc import x >>> intervals(x2 - 3) [((-2, -1), 1), ((1, 2), 1)] >>> intervals(x2 - 3, eps=1e-2) [((-26/15, -19/11), 1), ((19/11, 26/15), 1)] """ if not hasattr(F, '__iter__'): try: F = Poly(F) except GeneratorsNeeded: return [] return F.intervals(all=all, eps=eps, inf=inf, sup=sup, fast=fast, sqf=sqf) else: polys, opt = parallel_poly_from_expr(F, domain='QQ') if len(opt.gens) > 1: raise MultivariatePolynomialError for i, poly in enumerate(polys): polys[i] = poly.rep.rep if eps is not None: eps = opt.domain.convert(eps) if eps <= 0: raise ValueError("'eps' must be a positive rational") if inf is not None: inf = opt.domain.convert(inf) if sup is not None: sup = opt.domain.convert(sup) intervals = dup_isolate_real_roots_list(polys, opt.domain, eps=eps, inf=inf, sup=sup, strict=strict, fast=fast) result = [] for (s, t), indices in intervals: s, t = opt.domain.to_sympy(s), opt.domain.to_sympy(t) result.append(((s, t), indices)) return result @public def refine_root(f, s, t, eps=None, steps=None, fast=False, check_sqf=False): """ Refine an isolating interval of a root to the given precision. Examples ======== >>> from sympy import refine_root >>> from sympy.abc import x >>> refine_root(x2 - 3, 1, 2, eps=1e-2) (19/11, 26/15) """ try: F = Poly(f) except GeneratorsNeeded: raise PolynomialError( "can't refine a root of %s, not a polynomial" % f) return F.refine_root(s, t, eps=eps, steps=steps, fast=fast, check_sqf=check_sqf) @public def count_roots(f, inf=None, sup=None): """ Return the number of roots of ``f`` in ``[inf, sup]`` interval. If one of ``inf`` or ``sup`` is complex, it will return the number of roots in the complex rectangle with corners at ``inf`` and ``sup``. Examples ======== >>> from sympy import count_roots, I >>> from sympy.abc import x >>> count_roots(x4 - 4, -3, 3) 2 >>> count_roots(x4 - 4, 0, 1 + 3I) 1 """ try: F = Poly(f, greedy=False) except GeneratorsNeeded: raise PolynomialError("can't count roots of %s, not a polynomial" % f) return F.count_roots(inf=inf, sup=sup) @public def real_roots(f, multiple=True): """ Return a list of real roots with multiplicities of ``f``. Examples ======== >>> from sympy import real_roots >>> from sympy.abc import x >>> real_roots(2x*3 - 7x*2 + 4x + 4) [-1/2, 2, 2] """ try: F = Poly(f, greedy=False) except GeneratorsNeeded: raise PolynomialError( "can't compute real roots of %s, not a polynomial" % f) return F.real_roots(multiple=multiple) @public def nroots(f, n=15, maxsteps=50, cleanup=True): """ Compute numerical approximations of roots of ``f``. Examples ======== >>> from sympy import nroots >>> from sympy.abc import x >>> nroots(x2 - 3, n=15) [-1.73205080756888, 1.73205080756888] >>> nroots(x2 - 3, n=30) [-1.73205080756887729352744634151, 1.73205080756887729352744634151] """ try: F = Poly(f, greedy=False) except GeneratorsNeeded: raise PolynomialError( "can't compute numerical roots of %s, not a polynomial" % f) return F.nroots(n=n, maxsteps=maxsteps, cleanup=cleanup) @public def ground_roots(f, gens, args): """ Compute roots of ``f`` by factorization in the ground domain. Examples ======== >>> from sympy import ground_roots >>> from sympy.abc import x >>> ground_roots(x6 - 4x*4 + 4x3 - x2) {0: 2, 1: 2} """ options.allowed_flags(args, []) try: F, opt = poly_from_expr(f, gens, args) except PolificationFailed as exc: raise ComputationFailed('ground_roots', 1, exc) return F.ground_roots() @public def nth_power_roots_poly(f, n, gens, args): """ Construct a polynomial with n-th powers of roots of ``f``. Examples ======== >>> from sympy import nth_power_roots_poly, factor, roots >>> from sympy.abc import x >>> f = x4 - x2 + 1 >>> g = factor(nth_power_roots_poly(f, 2)) >>> g (x2 - x + 1)2 >>> R_f = [ (r2).expand() for r in roots(f) ] >>> R_g = roots(g).keys() >>> set(R_f) == set(R_g) True """ options.allowed_flags(args, []) try: F, opt = poly_from_expr(f, gens, args) except PolificationFailed as exc: raise ComputationFailed('nth_power_roots_poly', 1, exc) result = F.nth_power_roots_poly(n) if not opt.polys: return result.as_expr() else: return result @public def cancel(f, gens, *args): """ Cancel common factors in a rational function ``f``. Examples ======== >>> from sympy import cancel, sqrt, Symbol >>> from sympy.abc import x >>> A = Symbol('A', commutative=False) >>> cancel((2x2 - 2)/(x2 - 2x + 1)) (2x + 2)/(x - 1) >>> cancel((sqrt(3) + sqrt(15)A)/(sqrt(2) + sqrt(10)A)) sqrt(6)/2 """ from sympy.core.exprtools import factor_terms from sympy.functions.elementary.piecewise import Piecewise options.allowed_flags(args, ['polys']) f = sympify(f) if not isinstance(f, (tuple, Tuple)): if f.is_Number or isinstance(f, Relational) or not isinstance(f, Expr): return f f = factor_terms(f, radical=True) p, q = f.as_numer_denom() elif len(f) == 2: p, q = f elif isinstance(f, Tuple): return factor_terms(f) else: raise ValueError('unexpected argument: %s' % f) try: (F, G), opt = parallel_poly_from_expr((p, q), gens, args) except PolificationFailed: if not isinstance(f, (tuple, Tuple)): return f else: return S.One, p, q except PolynomialError as msg: if f.is_commutative and not f.has(Piecewise): raise PolynomialError(msg) # Handling of noncommutative and/or piecewise expressions if f.is_Add or f.is_Mul: c, nc = sift(f.args, lambda x: x.is_commutative is True and not x.has(Piecewise), binary=True) nc = [cancel(i) for i in nc] return f.func(cancel(f.func._from_args(c)), nc) else: reps = [] pot = preorder_traversal(f) next(pot) for e in pot: # XXX: This should really skip anything that's not Expr. if isinstance(e, (tuple, Tuple, BooleanAtom)): continue try: reps.append((e, cancel(e))) pot.skip() # this was handled successfully except NotImplementedError: pass return f.xreplace(dict(reps)) c, P, Q = F.cancel(G) if not isinstance(f, (tuple, Tuple)): return c(P.as_expr()/Q.as_expr()) else: if not opt.polys: return c, P.as_expr(), Q.as_expr() else: return c, P, Q @public def reduced(f, G, gens, *args): """ Reduces a polynomial ``f`` modulo a set of polynomials ``G``. Given a polynomial ``f`` and a set of polynomials ``G = (g_1, ..., g_n)``, computes a set of quotients ``q = (q_1, ..., q_n)`` and the remainder ``r`` such that ``f = q_1g_1 + ... + q_ng_n + r``, where ``r`` vanishes or ``r`` is a completely reduced polynomial with respect to ``G``. Examples ======== >>> from sympy import reduced >>> from sympy.abc import x, y >>> reduced(2x4 + y2 - x2 + y3, [x3 - x, y3 - y]) ([2x, 1], x2 + y2 + y) """ options.allowed_flags(args, ['polys', 'auto']) try: polys, opt = parallel_poly_from_expr([f] + list(G), gens, *args) except PolificationFailed as exc: raise ComputationFailed('reduced', 0, exc) domain = opt.domain retract = False if opt.auto and domain.is_Ring and not domain.is_Field: opt = opt.clone(dict(domain=domain.get_field())) retract = True from sympy.polys.rings import xring _ring, _ = xring(opt.gens, opt.domain, opt.order) for i, poly in enumerate(polys): poly = poly.set_domain(opt.domain).rep.to_dict() polys[i] = _ring.from_dict(poly) Q, r = polys[0].div(polys[1:]) Q = [Poly._from_dict(dict(q), opt) for q in Q] r = Poly._from_dict(dict(r), opt) if retract: try: _Q, _r = [q.to_ring() for q in Q], r.to_ring() except CoercionFailed: pass else: Q, r = _Q, _r if not opt.polys: return [q.as_expr() for q in Q], r.as_expr() else: return Q, r @public def groebner(F, gens, *args): """ Computes the reduced Groebner basis for a set of polynomials. Use the ``order`` argument to set the monomial ordering that will be used to compute the basis. Allowed orders are ``lex``, ``grlex`` and ``grevlex``. If no order is specified, it defaults to ``lex``. For more information on Groebner bases, see the references and the docstring of `solve_poly_system()`. Examples ======== Example taken from [1]. >>> from sympy import groebner >>> from sympy.abc import x, y >>> F = [xy - 2y, 2y2 - x2] >>> groebner(F, x, y, order='lex') GroebnerBasis([x*2 - 2y*2, xy - 2y, y3 - 2y], x, y, domain='ZZ', order='lex') >>> groebner(F, x, y, order='grlex') GroebnerBasis([y*3 - 2y, x*2 - 2y*2, xy - 2y], x, y, domain='ZZ', order='grlex') >>> groebner(F, x, y, order='grevlex') GroebnerBasis([y3 - 2y, x*2 - 2y*2, xy - 2y], x, y, domain='ZZ', order='grevlex') By default, an improved implementation of the Buchberger algorithm is used. Optionally, an implementation of the F5B algorithm can be used. The algorithm can be set using ``method`` flag or with the :func:`setup` function from :mod:`sympy.polys.polyconfig`: >>> F = [x2 - x - 1, (2x - 1) * y - (x10 - (1 - x)10)] >>> groebner(F, x, y, method='buchberger') GroebnerBasis([x2 - x - 1, y - 55], x, y, domain='ZZ', order='lex') >>> groebner(F, x, y, method='f5b') GroebnerBasis([x2 - x - 1, y - 55], x, y, domain='ZZ', order='lex') References ========== 1. [Buchberger01]_ 2. [Cox97]_ """ return GroebnerBasis(F, gens, args) @public def is_zero_dimensional(F, gens, *args): """ Checks if the ideal generated by a Groebner basis is zero-dimensional. The algorithm checks if the set of monomials not divisible by the leading monomial of any element of ``F`` is bounded. References ========== David A. Cox, John B. Little, Donal O'Shea. Ideals, Varieties and Algorithms, 3rd edition, p. 230 """ return GroebnerBasis(F, gens, *args).is_zero_dimensional @public class GroebnerBasis(Basic): """Represents a reduced Groebner basis. """ def __new__(cls, F, gens, *args): """Compute a reduced Groebner basis for a system of polynomials. """ options.allowed_flags(args, ['polys', 'method']) try: polys, opt = parallel_poly_from_expr(F, gens, *args) except PolificationFailed as exc: raise ComputationFailed('groebner', len(F), exc) from sympy.polys.rings import PolyRing ring = PolyRing(opt.gens, opt.domain, opt.order) polys = [ring.from_dict(poly.rep.to_dict()) for poly in polys if poly] G = _groebner(polys, ring, method=opt.method) G = [Poly._from_dict(g, opt) for g in G] return cls._new(G, opt) @classmethod def _new(cls, basis, options): obj = Basic.__new__(cls) obj._basis = tuple(basis) obj._options = options return obj @property def args(self): return (Tuple(self._basis), Tuple(self._options.gens)) @property def exprs(self): return [poly.as_expr() for poly in self._basis] @property def polys(self): return list(self._basis) @property def gens(self): return self._options.gens @property def domain(self): return self._options.domain @property def order(self): return self._options.order def __len__(self): return len(self._basis) def __iter__(self): if self._options.polys: return iter(self.polys) else: return iter(self.exprs) def __getitem__(self, item): if self._options.polys: basis = self.polys else: basis = self.exprs return basis[item] def __hash__(self): return hash((self._basis, tuple(self._options.items()))) def __eq__(self, other): if isinstance(other, self.__class__): return self._basis == other._basis and self._options == other._options elif iterable(other): return self.polys == list(other) or self.exprs == list(other) else: return False def __ne__(self, other): return not self == other @property def is_zero_dimensional(self): """ Checks if the ideal generated by a Groebner basis is zero-dimensional. The algorithm checks if the set of monomials not divisible by the leading monomial of any element of ``F`` is bounded. References ========== David A. Cox, John B. Little, Donal O'Shea. Ideals, Varieties and Algorithms, 3rd edition, p. 230 """ def single_var(monomial): return sum(map(bool, monomial)) == 1 exponents = Monomial([0]len(self.gens)) order = self._options.order for poly in self.polys: monomial = poly.LM(order=order) if single_var(monomial): exponents = monomial # If any element of the exponents vector is zero, then there's # a variable for which there's no degree bound and the ideal # generated by this Groebner basis isn't zero-dimensional. return all(exponents) def fglm(self, order): """ Convert a Groebner basis from one ordering to another. The FGLM algorithm converts reduced Groebner bases of zero-dimensional ideals from one ordering to another. This method is often used when it is infeasible to compute a Groebner basis with respect to a particular ordering directly. Examples ======== >>> from sympy.abc import x, y >>> from sympy import groebner >>> F = [x2 - 3y - x + 1, y*2 - 2x + y - 1] >>> G = groebner(F, x, y, order='grlex') >>> list(G.fglm('lex')) [2x - y2 - y + 1, y4 + 2y*3 - 3y*2 - 16y + 7] >>> list(groebner(F, x, y, order='lex')) [2x - y2 - y + 1, y4 + 2y*3 - 3y*2 - 16y + 7] References ========== .. [1] J.C. Faugere, P. Gianni, D. Lazard, T. Mora (1994). Efficient Computation of Zero-dimensional Groebner Bases by Change of Ordering """ opt = self._options src_order = opt.order dst_order = monomial_key(order) if src_order == dst_order: return self if not self.is_zero_dimensional: raise NotImplementedError("can't convert Groebner bases of ideals with positive dimension") polys = list(self._basis) domain = opt.domain opt = opt.clone(dict( domain=domain.get_field(), order=dst_order, )) from sympy.polys.rings import xring _ring, _ = xring(opt.gens, opt.domain, src_order) for i, poly in enumerate(polys): poly = poly.set_domain(opt.domain).rep.to_dict() polys[i] = _ring.from_dict(poly) G = matrix_fglm(polys, _ring, dst_order) G = [Poly._from_dict(dict(g), opt) for g in G] if not domain.is_Field: G = [g.clear_denoms(convert=True)[1] for g in G] opt.domain = domain return self._new(G, opt) def reduce(self, expr, auto=True): """ Reduces a polynomial modulo a Groebner basis. Given a polynomial ``f`` and a set of polynomials ``G = (g_1, ..., g_n)``, computes a set of quotients ``q = (q_1, ..., q_n)`` and the remainder ``r`` such that ``f = q_1f_1 + ... + q_nf_n + r``, where ``r`` vanishes or ``r`` is a completely reduced polynomial with respect to ``G``. Examples ======== >>> from sympy import groebner, expand >>> from sympy.abc import x, y >>> f = 2x4 - x2 + y3 + y2 >>> G = groebner([x3 - x, y3 - y]) >>> G.reduce(f) ([2x, 1], x2 + y2 + y) >>> Q, r = _ >>> expand(sum(qg for q, g in zip(Q, G)) + r) 2x4 - x2 + y3 + y2 >>> _ == f True """ poly = Poly._from_expr(expr, self._options) polys = [poly] + list(self._basis) opt = self._options domain = opt.domain retract = False if auto and domain.is_Ring and not domain.is_Field: opt = opt.clone(dict(domain=domain.get_field())) retract = True from sympy.polys.rings import xring _ring, _ = xring(opt.gens, opt.domain, opt.order) for i, poly in enumerate(polys): poly = poly.set_domain(opt.domain).rep.to_dict() polys[i] = _ring.from_dict(poly) Q, r = polys[0].div(polys[1:]) Q = [Poly._from_dict(dict(q), opt) for q in Q] r = Poly._from_dict(dict(r), opt) if retract: try: _Q, _r = [q.to_ring() for q in Q], r.to_ring() except CoercionFailed: pass else: Q, r = _Q, _r if not opt.polys: return [q.as_expr() for q in Q], r.as_expr() else: return Q, r def contains(self, poly): """ Check if ``poly`` belongs the ideal generated by ``self``. Examples ======== >>> from sympy import groebner >>> from sympy.abc import x, y >>> f = 2x3 + y3 + 3y >>> G = groebner([x2 + y2 - 1, xy - 2]) >>> G.contains(f) True >>> G.contains(f + 1) False """ return self.reduce(poly)[1] == 0 @public def poly(expr, gens, *args): """ Efficiently transform an expression into a polynomial. Examples ======== >>> from sympy import poly >>> from sympy.abc import x >>> poly(x(x2 + x - 1)2) Poly(x*5 + 2x4 - x3 - 2x2 + x, x, domain='ZZ') """ options.allowed_flags(args, []) def _poly(expr, opt): terms, poly_terms = [], [] for term in Add.make_args(expr): factors, poly_factors = [], [] for factor in Mul.make_args(term): if factor.is_Add: poly_factors.append(_poly(factor, opt)) elif factor.is_Pow and factor.base.is_Add and \ factor.exp.is_Integer and factor.exp >= 0: poly_factors.append( _poly(factor.base, opt).pow(factor.exp)) else: factors.append(factor) if not poly_factors: terms.append(term) else: product = poly_factors[0] for factor in poly_factors[1:]: product = product.mul(factor) if factors: factor = Mul(factors) if factor.is_Number: product = product.mul(factor) else: product = product.mul(Poly._from_expr(factor, opt)) poly_terms.append(product) if not poly_terms: result = Poly._from_expr(expr, opt) else: result = poly_terms[0] for term in poly_terms[1:]: result = result.add(term) if terms: term = Add(terms) if term.is_Number: result = result.add(term) else: result = result.add(Poly._from_expr(term, opt)) return result.reorder(opt.get('gens', ()), *args) expr = sympify(expr) if expr.is_Poly: return Poly(expr, gens, **args) if 'expand' not in args: args['expand'] = False opt = options.build_options(gens, args) return _poly(expr, opt)
1aebd2f54f4bf615d68f0a352f0644f7ff57531c27895085a463b16ed1e3fc9f	"""Functions for generating interesting polynomials, e.g. for benchmarking. """ from __future__ import print_function, division from sympy.core import Add, Mul, Symbol, sympify, Dummy, symbols from sympy.core.compatibility import range from sympy.core.singleton import S from sympy.functions.elementary.miscellaneous import sqrt from sympy.ntheory import nextprime from sympy.polys.densearith import ( dmp_add_term, dmp_neg, dmp_mul, dmp_sqr ) from sympy.polys.densebasic import ( dmp_zero, dmp_one, dmp_ground, dup_from_raw_dict, dmp_raise, dup_random ) from sympy.polys.domains import ZZ from sympy.polys.factortools import dup_zz_cyclotomic_poly from sympy.polys.polyclasses import DMP from sympy.polys.polytools import Poly, PurePoly from sympy.polys.polyutils import _analyze_gens from sympy.utilities import subsets, public @public def swinnerton_dyer_poly(n, x=None, polys=False): """Generates n-th Swinnerton-Dyer polynomial in `x`. Parameters ---------- n : int `n` decides the order of polynomial x : optional polys : bool, optional ``polys=True`` returns an expression, otherwise (default) returns an expression. """ from .numberfields import minimal_polynomial if n <= 0: raise ValueError( "can't generate Swinnerton-Dyer polynomial of order %s" % n) if x is not None: sympify(x) else: x = Dummy('x') if n > 3: p = 2 a = [sqrt(2)] for i in range(2, n + 1): p = nextprime(p) a.append(sqrt(p)) return minimal_polynomial(Add(a), x, polys=polys) if n == 1: ex = x2 - 2 elif n == 2: ex = x4 - 10x2 + 1 elif n == 3: ex = x8 - 40x6 + 352x*4 - 960x*2 + 576 return PurePoly(ex, x) if polys else ex @public def cyclotomic_poly(n, x=None, polys=False): """Generates cyclotomic polynomial of order `n` in `x`. Parameters ---------- n : int `n` decides the order of polynomial x : optional polys : bool, optional ``polys=True`` returns an expression, otherwise (default) returns an expression. """ if n <= 0: raise ValueError( "can't generate cyclotomic polynomial of order %s" % n) poly = DMP(dup_zz_cyclotomic_poly(int(n), ZZ), ZZ) if x is not None: poly = Poly.new(poly, x) else: poly = PurePoly.new(poly, Dummy('x')) return poly if polys else poly.as_expr() @public def symmetric_poly(n, gens, *args): """Generates symmetric polynomial of order `n`. Returns a Poly object when ``polys=True``, otherwise (default) returns an expression. """ # TODO: use an explicit keyword argument when Python 2 support is dropped gens = _analyze_gens(gens) if n < 0 or n > len(gens) or not gens: raise ValueError("can't generate symmetric polynomial of order %s for %s" % (n, gens)) elif not n: poly = S.One else: poly = Add([Mul(s) for s in subsets(gens, int(n))]) if not args.get('polys', False): return poly else: return Poly(poly, gens) @public def random_poly(x, n, inf, sup, domain=ZZ, polys=False): """Generates a polynomial of degree ``n`` with coefficients in ``[inf, sup]``. Parameters ---------- x `x` is the independent term of polynomial n : int `n` decides the order of polynomial inf Lower limit of range in which coefficients lie sup Upper limit of range in which coefficients lie domain : optional Decides what ring the coefficients are supposed to belong. Default is set to Integers. polys : bool, optional ``polys=True`` returns an expression, otherwise (default) returns an expression. """ poly = Poly(dup_random(n, inf, sup, domain), x, domain=domain) return poly if polys else poly.as_expr() @public def interpolating_poly(n, x, X='x', Y='y'): """Construct Lagrange interpolating polynomial for ``n`` data points. """ if isinstance(X, str): X = symbols("%s:%s" % (X, n)) if isinstance(Y, str): Y = symbols("%s:%s" % (Y, n)) coeffs = [] numert = Mul([(x - u) for u in X]) for i in range(n): numer = numert/(x - X[i]) denom = Mul([(X[i] - X[j]) for j in range(n) if i != j]) coeffs.append(numer/denom) return Add([coeffy for coeff, y in zip(coeffs, Y)]) def fateman_poly_F_1(n): """Fateman's GCD benchmark: trivial GCD """ Y = [Symbol('y_' + str(i)) for i in range(n + 1)] y_0, y_1 = Y[0], Y[1] u = y_0 + Add([y for y in Y[1:]]) v = y_02 + Add([y*2 for y in Y[1:]]) F = ((u + 1)(u + 2)).as_poly(Y) G = ((v + 1)(-3y_1y_02 + y_12 - 1)).as_poly(Y) H = Poly(1, Y) return F, G, H def dmp_fateman_poly_F_1(n, K): """Fateman's GCD benchmark: trivial GCD """ u = [K(1), K(0)] for i in range(n): u = [dmp_one(i, K), u] v = [K(1), K(0), K(0)] for i in range(0, n): v = [dmp_one(i, K), dmp_zero(i), v] m = n - 1 U = dmp_add_term(u, dmp_ground(K(1), m), 0, n, K) V = dmp_add_term(u, dmp_ground(K(2), m), 0, n, K) f = [[-K(3), K(0)], [], [K(1), K(0), -K(1)]] W = dmp_add_term(v, dmp_ground(K(1), m), 0, n, K) Y = dmp_raise(f, m, 1, K) F = dmp_mul(U, V, n, K) G = dmp_mul(W, Y, n, K) H = dmp_one(n, K) return F, G, H def fateman_poly_F_2(n): """Fateman's GCD benchmark: linearly dense quartic inputs """ Y = [Symbol('y_' + str(i)) for i in range(n + 1)] y_0 = Y[0] u = Add([y for y in Y[1:]]) H = Poly((y_0 + u + 1)2, Y) F = Poly((y_0 - u - 2)*2, Y) G = Poly((y_0 + u + 2)*2, Y) return HF, HG, H def dmp_fateman_poly_F_2(n, K): """Fateman's GCD benchmark: linearly dense quartic inputs """ u = [K(1), K(0)] for i in range(n - 1): u = [dmp_one(i, K), u] m = n - 1 v = dmp_add_term(u, dmp_ground(K(2), m - 1), 0, n, K) f = dmp_sqr([dmp_one(m, K), dmp_neg(v, m, K)], n, K) g = dmp_sqr([dmp_one(m, K), v], n, K) v = dmp_add_term(u, dmp_one(m - 1, K), 0, n, K) h = dmp_sqr([dmp_one(m, K), v], n, K) return dmp_mul(f, h, n, K), dmp_mul(g, h, n, K), h def fateman_poly_F_3(n): """Fateman's GCD benchmark: sparse inputs (deg f ~ vars f) """ Y = [Symbol('y_' + str(i)) for i in range(n + 1)] y_0 = Y[0] u = Add([y(n + 1) for y in Y[1:]]) H = Poly((y_0(n + 1) + u + 1)2, Y) F = Poly((y_0(n + 1) - u - 2)2, Y) G = Poly((y_0(n + 1) + u + 2)2, Y) return HF, HG, H def dmp_fateman_poly_F_3(n, K): """Fateman's GCD benchmark: sparse inputs (deg f ~ vars f) """ u = dup_from_raw_dict({n + 1: K.one}, K) for i in range(0, n - 1): u = dmp_add_term([u], dmp_one(i, K), n + 1, i + 1, K) v = dmp_add_term(u, dmp_ground(K(2), n - 2), 0, n, K) f = dmp_sqr( dmp_add_term([dmp_neg(v, n - 1, K)], dmp_one(n - 1, K), n + 1, n, K), n, K) g = dmp_sqr(dmp_add_term([v], dmp_one(n - 1, K), n + 1, n, K), n, K) v = dmp_add_term(u, dmp_one(n - 2, K), 0, n - 1, K) h = dmp_sqr(dmp_add_term([v], dmp_one(n - 1, K), n + 1, n, K), n, K) return dmp_mul(f, h, n, K), dmp_mul(g, h, n, K), h # A few useful polynomials from Wang's paper ('78). from sympy.polys.rings import ring def _f_0(): R, x, y, z = ring("x,y,z", ZZ) return x*2yz2 + 2x*2yz + 3x*2y + 2x2 + 3x + 4y2z*2 + 5y*2z + 6y2 + yz*2 + 2yz + y + 1 def _f_1(): R, x, y, z = ring("x,y,z", ZZ) return x3yz + x2y*2z2 + x2y2 + 20x*2yz + 30x*2y + x*2z*2 + 10x*2z + xy3z + 30xy*2z + 20xy*2 + xyz3 + 10xyz*2 + xyz + 610xy + 20xz2 + 230xz + 300x + y*2z*2 + 10y*2z + 30yz*2 + 320yz + 200y + 600z + 6000 def _f_2(): R, x, y, z = ring("x,y,z", ZZ) return x5y3 + x5y2z + x*5yz2 + x5z3 + x3y2 + x3yz + 90x*3y + 90x3z + x*2y*2z - 11x2y2 + x2z3 - 11x*2z*2 + yz - 11y + 90z - 990 def _f_3(): R, x, y, z = ring("x,y,z", ZZ) return x*5y2 + x4z4 + x4 + x3y*3z + x*3z + x*2y4 + x2y3z3 + x2yz5 + x2yz + xy2z*4 + xy*2 + xyz7 + xyz3 + xyz2 + y2z + yz4 def _f_4(): R, x, y, z = ring("x,y,z", ZZ) return -x9y*8z - x*8y*5z3 - x7y12z*2 - 5x*7y8 - x6y9z4 + x6y7z*3 + 3x*6y*7z - 5x6y*5z2 - x6y4z3 + x5y4z*5 + 3x*5y*4z3 - x5yz5 + x4y11z*4 + 3x*4y*11z2 - x4y8z*4 + 5x*4y*7z*2 + 15x*4y*7 - 5x*4y*4z2 + x3y8z*6 + 3x*3y*8z4 - x3y5z*6 + 5x*3y*4z*4 + 15x*3y*4z2 + x3y3z*5 + 3x*3y*3z*3 - 5x*3yz4 + x2z*7 + 3x*2z*5 + xy*7z*6 + 3xy7z*4 + 5xy3z*4 + 15xy3z2 + y4z8 + 3y*4z*6 + 5z*6 + 15z4 def _f_5(): R, x, y, z = ring("x,y,z", ZZ) return -x3 - 3x2y + 3x2z - 3xy*2 + 6xyz - 3xz2 - y3 + 3y2z - 3yz2 + z3 def _f_6(): R, x, y, z, t = ring("x,y,z,t", ZZ) return 2115x4y + 45x3z*3t*2 - 45x*3t*2 - 423xy4 - 47xy3 + 141xyz*3 + 94xyzt - 9y*3z*3t*2 + 9y*3t2 - y2z3t2 + y2t2 + 3z*6t*2 + 2z*4t*3 - 3z*3t*2 - 2zt3 def _w_1(): R, x, y, z = ring("x,y,z", ZZ) return 4x*6y*4z*2 + 4x*6y*3z*3 - 4x*6y*2z*4 - 4x*6yz5 + x5y*4z*3 + 12x*5y*3z - x*5y*2z*5 + 12x*5y*2z*2 - 12x*5yz3 - 12x*5z*4 + 8x*4y*4 + 6x*4y*3z*2 + 8x*4y*3z - 4x4y*2z*4 + 4x*4y*2z*3 - 8x*4y*2z*2 - 4x*4yz5 - 2x*4yz4 - 8x*4yz3 + 2x*3y*4z + x*3y*3z3 - x3y2z*5 - 2x*3y*2z*3 + 9x*3y*2z - 12x3yz3 + 12x*3yz2 - 12x*3z*4 + 3x*3z*3 + 6x*2y*3 - 6x*2y*2z*2 + 8x*2y*2z - 2x2yz4 - 8x*2yz3 + 2x*2yz2 + 2xy3z - 2xy*2z*3 - 3xyz + 3xz*3 - 2y*2 + 2yz2 def _w_2(): R, x, y = ring("x,y", ZZ) return 24x*8y*3 + 48x*8y*2 + 24x*7y*5 - 72x*7y*2 + 25x*6y*4 + 2x*6y*3 + 4x*6y + 8x6 + x5y6 + x5y3 - 12x5 + x4y5 - x4y*4 - 2x*4y*3 + 292x*4y2 - x3y6 + 3x*3y3 - x2y5 + 12x*2y*3 + 48x*2 - 12y**3 def f_polys(): return _f_0(), _f_1(), _f_2(), _f_3(), _f_4(), _f_5(), _f_6() def w_polys(): return _w_1(), _w_2()
f4d35385830506fbb072ace1902af34dd8b08b838cd43751a56c204e0f1f9e11	"""Implementation of matrix FGLM Groebner basis conversion algorithm. """ from __future__ import print_function, division from sympy.polys.monomials import monomial_mul, monomial_div from sympy.core.compatibility import range def matrix_fglm(F, ring, O_to): """ Converts the reduced Groebner basis ``F`` of a zero-dimensional ideal w.r.t. ``O_from`` to a reduced Groebner basis w.r.t. ``O_to``. References ========== .. [1] J.C. Faugere, P. Gianni, D. Lazard, T. Mora (1994). Efficient Computation of Zero-dimensional Groebner Bases by Change of Ordering """ domain = ring.domain ngens = ring.ngens ring_to = ring.clone(order=O_to) old_basis = _basis(F, ring) M = _representing_matrices(old_basis, F, ring) # V contains the normalforms (wrt O_from) of S S = [ring.zero_monom] V = [[domain.one] + [domain.zero] * (len(old_basis) - 1)] G = [] L = [(i, 0) for i in range(ngens)] # (i, j) corresponds to x_i * S[j] L.sort(key=lambda k_l: O_to(_incr_k(S[k_l[1]], k_l[0])), reverse=True) t = L.pop() P = _identity_matrix(len(old_basis), domain) while True: s = len(S) v = _matrix_mul(M[t[0]], V[t[1]]) _lambda = _matrix_mul(P, v) if all(_lambda[i] == domain.zero for i in range(s, len(old_basis))): # there is a linear combination of v by V lt = ring.term_new(_incr_k(S[t[1]], t[0]), domain.one) rest = ring.from_dict({S[i]: _lambda[i] for i in range(s)}) g = (lt - rest).set_ring(ring_to) if g: G.append(g) else: # v is linearly independent from V P = _update(s, _lambda, P) S.append(_incr_k(S[t[1]], t[0])) V.append(v) L.extend([(i, s) for i in range(ngens)]) L = list(set(L)) L.sort(key=lambda k_l: O_to(_incr_k(S[k_l[1]], k_l[0])), reverse=True) L = [(k, l) for (k, l) in L if all(monomial_div(_incr_k(S[l], k), g.LM) is None for g in G)] if not L: G = [ g.monic() for g in G ] return sorted(G, key=lambda g: O_to(g.LM), reverse=True) t = L.pop() def _incr_k(m, k): return tuple(list(m[:k]) + [m[k] + 1] + list(m[k + 1:])) def _identity_matrix(n, domain): M = [[domain.zero]n for _ in range(n)] for i in range(n): M[i][i] = domain.one return M def _matrix_mul(M, v): return [sum([row[i] v[i] for i in range(len(v))]) for row in M] def _update(s, _lambda, P): """ Update ``P`` such that for the updated `P'` `P' v = e_{s}`. """ k = min([j for j in range(s, len(_lambda)) if _lambda[j] != 0]) for r in range(len(_lambda)): if r != k: P[r] = [P[r][j] - (P[k][j] * _lambda[r]) / _lambda[k] for j in range(len(P[r]))] P[k] = [P[k][j] / _lambda[k] for j in range(len(P[k]))] P[k], P[s] = P[s], P[k] return P def _representing_matrices(basis, G, ring): r""" Compute the matrices corresponding to the linear maps `m \mapsto x_i m` for all variables `x_i`. """ domain = ring.domain u = ring.ngens-1 def var(i): return tuple([0] * i + [1] + [0] * (u - i)) def representing_matrix(m): M = [[domain.zero] * len(basis) for _ in range(len(basis))] for i, v in enumerate(basis): r = ring.term_new(monomial_mul(m, v), domain.one).rem(G) for monom, coeff in r.terms(): j = basis.index(monom) M[j][i] = coeff return M return [representing_matrix(var(i)) for i in range(u + 1)] def _basis(G, ring): r""" Computes a list of monomials which are not divisible by the leading monomials wrt to ``O`` of ``G``. These monomials are a basis of `K[X_1, \ldots, X_n]/(G)`. """ order = ring.order leading_monomials = [g.LM for g in G] candidates = [ring.zero_monom] basis = [] while candidates: t = candidates.pop() basis.append(t) new_candidates = [_incr_k(t, k) for k in range(ring.ngens) if all(monomial_div(_incr_k(t, k), lmg) is None for lmg in leading_monomials)] candidates.extend(new_candidates) candidates.sort(key=lambda m: order(m), reverse=True) basis = list(set(basis)) return sorted(basis, key=lambda m: order(m))
28334eb2fe01946114eda1ade6a4ada8c1c3e6ce79337e347cc01d202c0a682f	"""Basic tools for dense recursive polynomials in ``K[x]`` or ``K[X]``. """ from __future__ import print_function, division from sympy import oo from sympy.core import igcd from sympy.core.compatibility import range from sympy.polys.monomials import monomial_min, monomial_div from sympy.polys.orderings import monomial_key import random def poly_LC(f, K): """ Return leading coefficient of ``f``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import poly_LC >>> poly_LC([], ZZ) 0 >>> poly_LC([ZZ(1), ZZ(2), ZZ(3)], ZZ) 1 """ if not f: return K.zero else: return f[0] def poly_TC(f, K): """ Return trailing coefficient of ``f``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import poly_TC >>> poly_TC([], ZZ) 0 >>> poly_TC([ZZ(1), ZZ(2), ZZ(3)], ZZ) 3 """ if not f: return K.zero else: return f[-1] dup_LC = dmp_LC = poly_LC dup_TC = dmp_TC = poly_TC def dmp_ground_LC(f, u, K): """ Return the ground leading coefficient. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_ground_LC >>> f = ZZ.map([[[1], [2, 3]]]) >>> dmp_ground_LC(f, 2, ZZ) 1 """ while u: f = dmp_LC(f, K) u -= 1 return dup_LC(f, K) def dmp_ground_TC(f, u, K): """ Return the ground trailing coefficient. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_ground_TC >>> f = ZZ.map([[[1], [2, 3]]]) >>> dmp_ground_TC(f, 2, ZZ) 3 """ while u: f = dmp_TC(f, K) u -= 1 return dup_TC(f, K) def dmp_true_LT(f, u, K): """ Return the leading term ``c * x_1n_1 ... x_kn_k``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_true_LT >>> f = ZZ.map([[4], [2, 0], [3, 0, 0]]) >>> dmp_true_LT(f, 1, ZZ) ((2, 0), 4) """ monom = [] while u: monom.append(len(f) - 1) f, u = f[0], u - 1 if not f: monom.append(0) else: monom.append(len(f) - 1) return tuple(monom), dup_LC(f, K) def dup_degree(f): """ Return the leading degree of ``f`` in ``K[x]``. Note that the degree of 0 is negative infinity (the SymPy object -oo). Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_degree >>> f = ZZ.map([1, 2, 0, 3]) >>> dup_degree(f) 3 """ if not f: return -oo return len(f) - 1 def dmp_degree(f, u): """ Return the leading degree of ``f`` in ``x_0`` in ``K[X]``. Note that the degree of 0 is negative infinity (the SymPy object -oo). Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_degree >>> dmp_degree([[[]]], 2) -oo >>> f = ZZ.map([[2], [1, 2, 3]]) >>> dmp_degree(f, 1) 1 """ if dmp_zero_p(f, u): return -oo else: return len(f) - 1 def _rec_degree_in(g, v, i, j): """Recursive helper function for :func:`dmp_degree_in`.""" if i == j: return dmp_degree(g, v) v, i = v - 1, i + 1 return max([ _rec_degree_in(c, v, i, j) for c in g ]) def dmp_degree_in(f, j, u): """ Return the leading degree of ``f`` in ``x_j`` in ``K[X]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_degree_in >>> f = ZZ.map([[2], [1, 2, 3]]) >>> dmp_degree_in(f, 0, 1) 1 >>> dmp_degree_in(f, 1, 1) 2 """ if not j: return dmp_degree(f, u) if j < 0 or j > u: raise IndexError("0 <= j <= %s expected, got %s" % (u, j)) return _rec_degree_in(f, u, 0, j) def _rec_degree_list(g, v, i, degs): """Recursive helper for :func:`dmp_degree_list`.""" degs[i] = max(degs[i], dmp_degree(g, v)) if v > 0: v, i = v - 1, i + 1 for c in g: _rec_degree_list(c, v, i, degs) def dmp_degree_list(f, u): """ Return a list of degrees of ``f`` in ``K[X]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_degree_list >>> f = ZZ.map([[1], [1, 2, 3]]) >>> dmp_degree_list(f, 1) (1, 2) """ degs = [-oo](u + 1) _rec_degree_list(f, u, 0, degs) return tuple(degs) def dup_strip(f): """ Remove leading zeros from ``f`` in ``K[x]``. Examples ======== >>> from sympy.polys.densebasic import dup_strip >>> dup_strip([0, 0, 1, 2, 3, 0]) [1, 2, 3, 0] """ if not f or f[0]: return f i = 0 for cf in f: if cf: break else: i += 1 return f[i:] def dmp_strip(f, u): """ Remove leading zeros from ``f`` in ``K[X]``. Examples ======== >>> from sympy.polys.densebasic import dmp_strip >>> dmp_strip([[], [0, 1, 2], [1]], 1) [[0, 1, 2], [1]] """ if not u: return dup_strip(f) if dmp_zero_p(f, u): return f i, v = 0, u - 1 for c in f: if not dmp_zero_p(c, v): break else: i += 1 if i == len(f): return dmp_zero(u) else: return f[i:] def _rec_validate(f, g, i, K): """Recursive helper for :func:`dmp_validate`.""" if type(g) is not list: if K is not None and not K.of_type(g): raise TypeError("%s in %s in not of type %s" % (g, f, K.dtype)) return set([i - 1]) elif not g: return set([i]) else: levels = set([]) for c in g: levels \|= _rec_validate(f, c, i + 1, K) return levels def _rec_strip(g, v): """Recursive helper for :func:`_rec_strip`.""" if not v: return dup_strip(g) w = v - 1 return dmp_strip([ _rec_strip(c, w) for c in g ], v) def dmp_validate(f, K=None): """ Return the number of levels in ``f`` and recursively strip it. Examples ======== >>> from sympy.polys.densebasic import dmp_validate >>> dmp_validate([[], [0, 1, 2], [1]]) ([[1, 2], [1]], 1) >>> dmp_validate([[1], 1]) Traceback (most recent call last): ... ValueError: invalid data structure for a multivariate polynomial """ levels = _rec_validate(f, f, 0, K) u = levels.pop() if not levels: return _rec_strip(f, u), u else: raise ValueError( "invalid data structure for a multivariate polynomial") def dup_reverse(f): """ Compute ``xn f(1/x)``, i.e.: reverse ``f`` in ``K[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_reverse >>> f = ZZ.map([1, 2, 3, 0]) >>> dup_reverse(f) [3, 2, 1] """ return dup_strip(list(reversed(f))) def dup_copy(f): """ Create a new copy of a polynomial ``f`` in ``K[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_copy >>> f = ZZ.map([1, 2, 3, 0]) >>> dup_copy([1, 2, 3, 0]) [1, 2, 3, 0] """ return list(f) def dmp_copy(f, u): """ Create a new copy of a polynomial ``f`` in ``K[X]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_copy >>> f = ZZ.map([[1], [1, 2]]) >>> dmp_copy(f, 1) [[1], [1, 2]] """ if not u: return list(f) v = u - 1 return [ dmp_copy(c, v) for c in f ] def dup_to_tuple(f): """ Convert `f` into a tuple. This is needed for hashing. This is similar to dup_copy(). Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_copy >>> f = ZZ.map([1, 2, 3, 0]) >>> dup_copy([1, 2, 3, 0]) [1, 2, 3, 0] """ return tuple(f) def dmp_to_tuple(f, u): """ Convert `f` into a nested tuple of tuples. This is needed for hashing. This is similar to dmp_copy(). Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_to_tuple >>> f = ZZ.map([[1], [1, 2]]) >>> dmp_to_tuple(f, 1) ((1,), (1, 2)) """ if not u: return tuple(f) v = u - 1 return tuple(dmp_to_tuple(c, v) for c in f) def dup_normal(f, K): """ Normalize univariate polynomial in the given domain. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_normal >>> dup_normal([0, 1.5, 2, 3], ZZ) [1, 2, 3] """ return dup_strip([ K.normal(c) for c in f ]) def dmp_normal(f, u, K): """ Normalize a multivariate polynomial in the given domain. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_normal >>> dmp_normal([[], [0, 1.5, 2]], 1, ZZ) [[1, 2]] """ if not u: return dup_normal(f, K) v = u - 1 return dmp_strip([ dmp_normal(c, v, K) for c in f ], u) def dup_convert(f, K0, K1): """ Convert the ground domain of ``f`` from ``K0`` to ``K1``. Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_convert >>> R, x = ring("x", ZZ) >>> dup_convert([R(1), R(2)], R.to_domain(), ZZ) [1, 2] >>> dup_convert([ZZ(1), ZZ(2)], ZZ, R.to_domain()) [1, 2] """ if K0 is not None and K0 == K1: return f else: return dup_strip([ K1.convert(c, K0) for c in f ]) def dmp_convert(f, u, K0, K1): """ Convert the ground domain of ``f`` from ``K0`` to ``K1``. Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_convert >>> R, x = ring("x", ZZ) >>> dmp_convert([[R(1)], [R(2)]], 1, R.to_domain(), ZZ) [[1], [2]] >>> dmp_convert([[ZZ(1)], [ZZ(2)]], 1, ZZ, R.to_domain()) [[1], [2]] """ if not u: return dup_convert(f, K0, K1) if K0 is not None and K0 == K1: return f v = u - 1 return dmp_strip([ dmp_convert(c, v, K0, K1) for c in f ], u) def dup_from_sympy(f, K): """ Convert the ground domain of ``f`` from SymPy to ``K``. Examples ======== >>> from sympy import S >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_from_sympy >>> dup_from_sympy([S(1), S(2)], ZZ) == [ZZ(1), ZZ(2)] True """ return dup_strip([ K.from_sympy(c) for c in f ]) def dmp_from_sympy(f, u, K): """ Convert the ground domain of ``f`` from SymPy to ``K``. Examples ======== >>> from sympy import S >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_from_sympy >>> dmp_from_sympy([[S(1)], [S(2)]], 1, ZZ) == [[ZZ(1)], [ZZ(2)]] True """ if not u: return dup_from_sympy(f, K) v = u - 1 return dmp_strip([ dmp_from_sympy(c, v, K) for c in f ], u) def dup_nth(f, n, K): """ Return the ``n``-th coefficient of ``f`` in ``K[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_nth >>> f = ZZ.map([1, 2, 3]) >>> dup_nth(f, 0, ZZ) 3 >>> dup_nth(f, 4, ZZ) 0 """ if n < 0: raise IndexError("'n' must be non-negative, got %i" % n) elif n >= len(f): return K.zero else: return f[dup_degree(f) - n] def dmp_nth(f, n, u, K): """ Return the ``n``-th coefficient of ``f`` in ``K[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_nth >>> f = ZZ.map([[1], [2], [3]]) >>> dmp_nth(f, 0, 1, ZZ) [3] >>> dmp_nth(f, 4, 1, ZZ) [] """ if n < 0: raise IndexError("'n' must be non-negative, got %i" % n) elif n >= len(f): return dmp_zero(u - 1) else: return f[dmp_degree(f, u) - n] def dmp_ground_nth(f, N, u, K): """ Return the ground ``n``-th coefficient of ``f`` in ``K[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_ground_nth >>> f = ZZ.map([[1], [2, 3]]) >>> dmp_ground_nth(f, (0, 1), 1, ZZ) 2 """ v = u for n in N: if n < 0: raise IndexError("`n` must be non-negative, got %i" % n) elif n >= len(f): return K.zero else: d = dmp_degree(f, v) if d == -oo: d = -1 f, v = f[d - n], v - 1 return f def dmp_zero_p(f, u): """ Return ``True`` if ``f`` is zero in ``K[X]``. Examples ======== >>> from sympy.polys.densebasic import dmp_zero_p >>> dmp_zero_p([[[[[]]]]], 4) True >>> dmp_zero_p([[[[[1]]]]], 4) False """ while u: if len(f) != 1: return False f = f[0] u -= 1 return not f def dmp_zero(u): """ Return a multivariate zero. Examples ======== >>> from sympy.polys.densebasic import dmp_zero >>> dmp_zero(4) [[[[[]]]]] """ r = [] for i in range(u): r = [r] return r def dmp_one_p(f, u, K): """ Return ``True`` if ``f`` is one in ``K[X]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_one_p >>> dmp_one_p([[[ZZ(1)]]], 2, ZZ) True """ return dmp_ground_p(f, K.one, u) def dmp_one(u, K): """ Return a multivariate one over ``K``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_one >>> dmp_one(2, ZZ) [[[1]]] """ return dmp_ground(K.one, u) def dmp_ground_p(f, c, u): """ Return True if ``f`` is constant in ``K[X]``. Examples ======== >>> from sympy.polys.densebasic import dmp_ground_p >>> dmp_ground_p([[[3]]], 3, 2) True >>> dmp_ground_p([[[4]]], None, 2) True """ if c is not None and not c: return dmp_zero_p(f, u) while u: if len(f) != 1: return False f = f[0] u -= 1 if c is None: return len(f) <= 1 else: return f == [c] def dmp_ground(c, u): """ Return a multivariate constant. Examples ======== >>> from sympy.polys.densebasic import dmp_ground >>> dmp_ground(3, 5) [[[[[[3]]]]]] >>> dmp_ground(1, -1) 1 """ if not c: return dmp_zero(u) for i in range(u + 1): c = [c] return c def dmp_zeros(n, u, K): """ Return a list of multivariate zeros. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_zeros >>> dmp_zeros(3, 2, ZZ) [[[[]]], [[[]]], [[[]]]] >>> dmp_zeros(3, -1, ZZ) [0, 0, 0] """ if not n: return [] if u < 0: return [K.zero]n else: return [ dmp_zero(u) for i in range(n) ] def dmp_grounds(c, n, u): """ Return a list of multivariate constants. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_grounds >>> dmp_grounds(ZZ(4), 3, 2) [[[[4]]], [[[4]]], [[[4]]]] >>> dmp_grounds(ZZ(4), 3, -1) [4, 4, 4] """ if not n: return [] if u < 0: return [c]n else: return [ dmp_ground(c, u) for i in range(n) ] def dmp_negative_p(f, u, K): """ Return ``True`` if ``LC(f)`` is negative. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_negative_p >>> dmp_negative_p([[ZZ(1)], [-ZZ(1)]], 1, ZZ) False >>> dmp_negative_p([[-ZZ(1)], [ZZ(1)]], 1, ZZ) True """ return K.is_negative(dmp_ground_LC(f, u, K)) def dmp_positive_p(f, u, K): """ Return ``True`` if ``LC(f)`` is positive. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_positive_p >>> dmp_positive_p([[ZZ(1)], [-ZZ(1)]], 1, ZZ) True >>> dmp_positive_p([[-ZZ(1)], [ZZ(1)]], 1, ZZ) False """ return K.is_positive(dmp_ground_LC(f, u, K)) def dup_from_dict(f, K): """ Create a ``K[x]`` polynomial from a ``dict``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_from_dict >>> dup_from_dict({(0,): ZZ(7), (2,): ZZ(5), (4,): ZZ(1)}, ZZ) [1, 0, 5, 0, 7] >>> dup_from_dict({}, ZZ) [] """ if not f: return [] n, h = max(f.keys()), [] if type(n) is int: for k in range(n, -1, -1): h.append(f.get(k, K.zero)) else: (n,) = n for k in range(n, -1, -1): h.append(f.get((k,), K.zero)) return dup_strip(h) def dup_from_raw_dict(f, K): """ Create a ``K[x]`` polynomial from a raw ``dict``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_from_raw_dict >>> dup_from_raw_dict({0: ZZ(7), 2: ZZ(5), 4: ZZ(1)}, ZZ) [1, 0, 5, 0, 7] """ if not f: return [] n, h = max(f.keys()), [] for k in range(n, -1, -1): h.append(f.get(k, K.zero)) return dup_strip(h) def dmp_from_dict(f, u, K): """ Create a ``K[X]`` polynomial from a ``dict``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_from_dict >>> dmp_from_dict({(0, 0): ZZ(3), (0, 1): ZZ(2), (2, 1): ZZ(1)}, 1, ZZ) [[1, 0], [], [2, 3]] >>> dmp_from_dict({}, 0, ZZ) [] """ if not u: return dup_from_dict(f, K) if not f: return dmp_zero(u) coeffs = {} for monom, coeff in f.items(): head, tail = monom[0], monom[1:] if head in coeffs: coeffs[head][tail] = coeff else: coeffs[head] = { tail: coeff } n, v, h = max(coeffs.keys()), u - 1, [] for k in range(n, -1, -1): coeff = coeffs.get(k) if coeff is not None: h.append(dmp_from_dict(coeff, v, K)) else: h.append(dmp_zero(v)) return dmp_strip(h, u) def dup_to_dict(f, K=None, zero=False): """ Convert ``K[x]`` polynomial to a ``dict``. Examples ======== >>> from sympy.polys.densebasic import dup_to_dict >>> dup_to_dict([1, 0, 5, 0, 7]) {(0,): 7, (2,): 5, (4,): 1} >>> dup_to_dict([]) {} """ if not f and zero: return {(0,): K.zero} n, result = len(f) - 1, {} for k in range(0, n + 1): if f[n - k]: result[(k,)] = f[n - k] return result def dup_to_raw_dict(f, K=None, zero=False): """ Convert a ``K[x]`` polynomial to a raw ``dict``. Examples ======== >>> from sympy.polys.densebasic import dup_to_raw_dict >>> dup_to_raw_dict([1, 0, 5, 0, 7]) {0: 7, 2: 5, 4: 1} """ if not f and zero: return {0: K.zero} n, result = len(f) - 1, {} for k in range(0, n + 1): if f[n - k]: result[k] = f[n - k] return result def dmp_to_dict(f, u, K=None, zero=False): """ Convert a ``K[X]`` polynomial to a ``dict````. Examples ======== >>> from sympy.polys.densebasic import dmp_to_dict >>> dmp_to_dict([[1, 0], [], [2, 3]], 1) {(0, 0): 3, (0, 1): 2, (2, 1): 1} >>> dmp_to_dict([], 0) {} """ if not u: return dup_to_dict(f, K, zero=zero) if dmp_zero_p(f, u) and zero: return {(0,)(u + 1): K.zero} n, v, result = dmp_degree(f, u), u - 1, {} if n == -oo: n = -1 for k in range(0, n + 1): h = dmp_to_dict(f[n - k], v) for exp, coeff in h.items(): result[(k,) + exp] = coeff return result def dmp_swap(f, i, j, u, K): """ Transform ``K[..x_i..x_j..]`` to ``K[..x_j..x_i..]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_swap >>> f = ZZ.map([[[2], [1, 0]], []]) >>> dmp_swap(f, 0, 1, 2, ZZ) [[[2], []], [[1, 0], []]] >>> dmp_swap(f, 1, 2, 2, ZZ) [[[1], [2, 0]], [[]]] >>> dmp_swap(f, 0, 2, 2, ZZ) [[[1, 0]], [[2, 0], []]] """ if i < 0 or j < 0 or i > u or j > u: raise IndexError("0 <= i < j <= %s expected" % u) elif i == j: return f F, H = dmp_to_dict(f, u), {} for exp, coeff in F.items(): H[exp[:i] + (exp[j],) + exp[i + 1:j] + (exp[i],) + exp[j + 1:]] = coeff return dmp_from_dict(H, u, K) def dmp_permute(f, P, u, K): """ Return a polynomial in ``K[x_{P(1)},..,x_{P(n)}]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_permute >>> f = ZZ.map([[[2], [1, 0]], []]) >>> dmp_permute(f, [1, 0, 2], 2, ZZ) [[[2], []], [[1, 0], []]] >>> dmp_permute(f, [1, 2, 0], 2, ZZ) [[[1], []], [[2, 0], []]] """ F, H = dmp_to_dict(f, u), {} for exp, coeff in F.items(): new_exp = [0]len(exp) for e, p in zip(exp, P): new_exp[p] = e H[tuple(new_exp)] = coeff return dmp_from_dict(H, u, K) def dmp_nest(f, l, K): """ Return a multivariate value nested ``l``-levels. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_nest >>> dmp_nest([[ZZ(1)]], 2, ZZ) [[[[1]]]] """ if not isinstance(f, list): return dmp_ground(f, l) for i in range(l): f = [f] return f def dmp_raise(f, l, u, K): """ Return a multivariate polynomial raised ``l``-levels. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_raise >>> f = ZZ.map([[], [1, 2]]) >>> dmp_raise(f, 2, 1, ZZ) [[[[]]], [[[1]], [[2]]]] """ if not l: return f if not u: if not f: return dmp_zero(l) k = l - 1 return [ dmp_ground(c, k) for c in f ] v = u - 1 return [ dmp_raise(c, l, v, K) for c in f ] def dup_deflate(f, K): """ Map ``xm`` to ``y`` in a polynomial in ``K[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_deflate >>> f = ZZ.map([1, 0, 0, 1, 0, 0, 1]) >>> dup_deflate(f, ZZ) (3, [1, 1, 1]) """ if dup_degree(f) <= 0: return 1, f g = 0 for i in range(len(f)): if not f[-i - 1]: continue g = igcd(g, i) if g == 1: return 1, f return g, f[::g] def dmp_deflate(f, u, K): """ Map ``x_im_i`` to ``y_i`` in a polynomial in ``K[X]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_deflate >>> f = ZZ.map([[1, 0, 0, 2], [], [3, 0, 0, 4]]) >>> dmp_deflate(f, 1, ZZ) ((2, 3), [[1, 2], [3, 4]]) """ if dmp_zero_p(f, u): return (1,)(u + 1), f F = dmp_to_dict(f, u) B = [0](u + 1) for M in F.keys(): for i, m in enumerate(M): B[i] = igcd(B[i], m) for i, b in enumerate(B): if not b: B[i] = 1 B = tuple(B) if all(b == 1 for b in B): return B, f H = {} for A, coeff in F.items(): N = [ a // b for a, b in zip(A, B) ] H[tuple(N)] = coeff return B, dmp_from_dict(H, u, K) def dup_multi_deflate(polys, K): """ Map ``xm`` to ``y`` in a set of polynomials in ``K[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_multi_deflate >>> f = ZZ.map([1, 0, 2, 0, 3]) >>> g = ZZ.map([4, 0, 0]) >>> dup_multi_deflate((f, g), ZZ) (2, ([1, 2, 3], [4, 0])) """ G = 0 for p in polys: if dup_degree(p) <= 0: return 1, polys g = 0 for i in range(len(p)): if not p[-i - 1]: continue g = igcd(g, i) if g == 1: return 1, polys G = igcd(G, g) return G, tuple([ p[::G] for p in polys ]) def dmp_multi_deflate(polys, u, K): """ Map ``x_im_i`` to ``y_i`` in a set of polynomials in ``K[X]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_multi_deflate >>> f = ZZ.map([[1, 0, 0, 2], [], [3, 0, 0, 4]]) >>> g = ZZ.map([[1, 0, 2], [], [3, 0, 4]]) >>> dmp_multi_deflate((f, g), 1, ZZ) ((2, 1), ([[1, 0, 0, 2], [3, 0, 0, 4]], [[1, 0, 2], [3, 0, 4]])) """ if not u: M, H = dup_multi_deflate(polys, K) return (M,), H F, B = [], [0](u + 1) for p in polys: f = dmp_to_dict(p, u) if not dmp_zero_p(p, u): for M in f.keys(): for i, m in enumerate(M): B[i] = igcd(B[i], m) F.append(f) for i, b in enumerate(B): if not b: B[i] = 1 B = tuple(B) if all(b == 1 for b in B): return B, polys H = [] for f in F: h = {} for A, coeff in f.items(): N = [ a // b for a, b in zip(A, B) ] h[tuple(N)] = coeff H.append(dmp_from_dict(h, u, K)) return B, tuple(H) def dup_inflate(f, m, K): """ Map ``y`` to ``xm`` in a polynomial in ``K[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_inflate >>> f = ZZ.map([1, 1, 1]) >>> dup_inflate(f, 3, ZZ) [1, 0, 0, 1, 0, 0, 1] """ if m <= 0: raise IndexError("'m' must be positive, got %s" % m) if m == 1 or not f: return f result = [f[0]] for coeff in f[1:]: result.extend([K.zero](m - 1)) result.append(coeff) return result def _rec_inflate(g, M, v, i, K): """Recursive helper for :func:`dmp_inflate`.""" if not v: return dup_inflate(g, M[i], K) if M[i] <= 0: raise IndexError("all M[i] must be positive, got %s" % M[i]) w, j = v - 1, i + 1 g = [ _rec_inflate(c, M, w, j, K) for c in g ] result = [g[0]] for coeff in g[1:]: for _ in range(1, M[i]): result.append(dmp_zero(w)) result.append(coeff) return result def dmp_inflate(f, M, u, K): """ Map ``y_i`` to ``x_i*k_i`` in a polynomial in ``K[X]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_inflate >>> f = ZZ.map([[1, 2], [3, 4]]) >>> dmp_inflate(f, (2, 3), 1, ZZ) [[1, 0, 0, 2], [], [3, 0, 0, 4]] """ if not u: return dup_inflate(f, M[0], K) if all(m == 1 for m in M): return f else: return _rec_inflate(f, M, u, 0, K) def dmp_exclude(f, u, K): """ Exclude useless levels from ``f``. Return the levels excluded, the new excluded ``f``, and the new ``u``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_exclude >>> f = ZZ.map([[[1]], [[1], [2]]]) >>> dmp_exclude(f, 2, ZZ) ([2], [[1], [1, 2]], 1) """ if not u or dmp_ground_p(f, None, u): return [], f, u J, F = [], dmp_to_dict(f, u) for j in range(0, u + 1): for monom in F.keys(): if monom[j]: break else: J.append(j) if not J: return [], f, u f = {} for monom, coeff in F.items(): monom = list(monom) for j in reversed(J): del monom[j] f[tuple(monom)] = coeff u -= len(J) return J, dmp_from_dict(f, u, K), u def dmp_include(f, J, u, K): """ Include useless levels in ``f``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_include >>> f = ZZ.map([[1], [1, 2]]) >>> dmp_include(f, [2], 1, ZZ) [[[1]], [[1], [2]]] """ if not J: return f F, f = dmp_to_dict(f, u), {} for monom, coeff in F.items(): monom = list(monom) for j in J: monom.insert(j, 0) f[tuple(monom)] = coeff u += len(J) return dmp_from_dict(f, u, K) def dmp_inject(f, u, K, front=False): """ Convert ``f`` from ``K[X][Y]`` to ``K[X,Y]``. Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_inject >>> R, x,y = ring("x,y", ZZ) >>> dmp_inject([R(1), x + 2], 0, R.to_domain()) ([[[1]], [[1], [2]]], 2) >>> dmp_inject([R(1), x + 2], 0, R.to_domain(), front=True) ([[[1]], [[1, 2]]], 2) """ f, h = dmp_to_dict(f, u), {} v = K.ngens - 1 for f_monom, g in f.items(): g = g.to_dict() for g_monom, c in g.items(): if front: h[g_monom + f_monom] = c else: h[f_monom + g_monom] = c w = u + v + 1 return dmp_from_dict(h, w, K.dom), w def dmp_eject(f, u, K, front=False): """ Convert ``f`` from ``K[X,Y]`` to ``K[X][Y]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_eject >>> dmp_eject([[[1]], [[1], [2]]], 2, ZZ['x', 'y']) [1, x + 2] """ f, h = dmp_to_dict(f, u), {} n = K.ngens v = u - K.ngens + 1 for monom, c in f.items(): if front: g_monom, f_monom = monom[:n], monom[n:] else: g_monom, f_monom = monom[-n:], monom[:-n] if f_monom in h: h[f_monom][g_monom] = c else: h[f_monom] = {g_monom: c} for monom, c in h.items(): h[monom] = K(c) return dmp_from_dict(h, v - 1, K) def dup_terms_gcd(f, K): """ Remove GCD of terms from ``f`` in ``K[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_terms_gcd >>> f = ZZ.map([1, 0, 1, 0, 0]) >>> dup_terms_gcd(f, ZZ) (2, [1, 0, 1]) """ if dup_TC(f, K) or not f: return 0, f i = 0 for c in reversed(f): if not c: i += 1 else: break return i, f[:-i] def dmp_terms_gcd(f, u, K): """ Remove GCD of terms from ``f`` in ``K[X]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_terms_gcd >>> f = ZZ.map([[1, 0], [1, 0, 0], [], []]) >>> dmp_terms_gcd(f, 1, ZZ) ((2, 1), [[1], [1, 0]]) """ if dmp_ground_TC(f, u, K) or dmp_zero_p(f, u): return (0,)(u + 1), f F = dmp_to_dict(f, u) G = monomial_min(list(F.keys())) if all(g == 0 for g in G): return G, f f = {} for monom, coeff in F.items(): f[monomial_div(monom, G)] = coeff return G, dmp_from_dict(f, u, K) def _rec_list_terms(g, v, monom): """Recursive helper for :func:`dmp_list_terms`.""" d, terms = dmp_degree(g, v), [] if not v: for i, c in enumerate(g): if not c: continue terms.append((monom + (d - i,), c)) else: w = v - 1 for i, c in enumerate(g): terms.extend(_rec_list_terms(c, w, monom + (d - i,))) return terms def dmp_list_terms(f, u, K, order=None): """ List all non-zero terms from ``f`` in the given order ``order``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_list_terms >>> f = ZZ.map([[1, 1], [2, 3]]) >>> dmp_list_terms(f, 1, ZZ) [((1, 1), 1), ((1, 0), 1), ((0, 1), 2), ((0, 0), 3)] >>> dmp_list_terms(f, 1, ZZ, order='grevlex') [((1, 1), 1), ((1, 0), 1), ((0, 1), 2), ((0, 0), 3)] """ def sort(terms, O): return sorted(terms, key=lambda term: O(term[0]), reverse=True) terms = _rec_list_terms(f, u, ()) if not terms: return [((0,)(u + 1), K.zero)] if order is None: return terms else: return sort(terms, monomial_key(order)) def dup_apply_pairs(f, g, h, args, K): """ Apply ``h`` to pairs of coefficients of ``f`` and ``g``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_apply_pairs >>> h = lambda x, y, z: 2x + y - z >>> dup_apply_pairs([1, 2, 3], [3, 2, 1], h, (1,), ZZ) [4, 5, 6] """ n, m = len(f), len(g) if n != m: if n > m: g = [K.zero](n - m) + g else: f = [K.zero](m - n) + f result = [] for a, b in zip(f, g): result.append(h(a, b, args)) return dup_strip(result) def dmp_apply_pairs(f, g, h, args, u, K): """ Apply ``h`` to pairs of coefficients of ``f`` and ``g``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_apply_pairs >>> h = lambda x, y, z: 2x + y - z >>> dmp_apply_pairs([[1], [2, 3]], [[3], [2, 1]], h, (1,), 1, ZZ) [[4], [5, 6]] """ if not u: return dup_apply_pairs(f, g, h, args, K) n, m, v = len(f), len(g), u - 1 if n != m: if n > m: g = dmp_zeros(n - m, v, K) + g else: f = dmp_zeros(m - n, v, K) + f result = [] for a, b in zip(f, g): result.append(dmp_apply_pairs(a, b, h, args, v, K)) return dmp_strip(result, u) def dup_slice(f, m, n, K): """Take a continuous subsequence of terms of ``f`` in ``K[x]``. """ k = len(f) if k >= m: M = k - m else: M = 0 if k >= n: N = k - n else: N = 0 f = f[N:M] if not f: return [] else: return f + [K.zero]m def dmp_slice(f, m, n, u, K): """Take a continuous subsequence of terms of ``f`` in ``K[X]``. """ return dmp_slice_in(f, m, n, 0, u, K) def dmp_slice_in(f, m, n, j, u, K): """Take a continuous subsequence of terms of ``f`` in ``x_j`` in ``K[X]``. """ if j < 0 or j > u: raise IndexError("-%s <= j < %s expected, got %s" % (u, u, j)) if not u: return dup_slice(f, m, n, K) f, g = dmp_to_dict(f, u), {} for monom, coeff in f.items(): k = monom[j] if k < m or k >= n: monom = monom[:j] + (0,) + monom[j + 1:] if monom in g: g[monom] += coeff else: g[monom] = coeff return dmp_from_dict(g, u, K) def dup_random(n, a, b, K): """ Return a polynomial of degree ``n`` with coefficients in ``[a, b]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_random >>> dup_random(3, -10, 10, ZZ) #doctest: +SKIP [-2, -8, 9, -4] """ f = [ K.convert(random.randint(a, b)) for _ in range(0, n + 1) ] while not f[0]: f[0] = K.convert(random.randint(a, b)) return f
478cb99e950a6031218bafb4855728ca3d184a4853128921f27de3640dc2ab85	"""Algorithms for computing symbolic roots of polynomials. """ from __future__ import print_function, division import math from sympy.core import S, I, pi from sympy.core.compatibility import ordered, range, reduce from sympy.core.exprtools import factor_terms from sympy.core.function import _mexpand from sympy.core.logic import fuzzy_not from sympy.core.mul import expand_2arg, Mul from sympy.core.numbers import Rational, igcd, comp from sympy.core.power import Pow from sympy.core.relational import Eq from sympy.core.symbol import Dummy, Symbol, symbols from sympy.core.sympify import sympify from sympy.functions import exp, sqrt, im, cos, acos, Piecewise from sympy.functions.elementary.miscellaneous import root from sympy.ntheory import divisors, isprime, nextprime from sympy.polys.polyerrors import (PolynomialError, GeneratorsNeeded, DomainError) from sympy.polys.polyquinticconst import PolyQuintic from sympy.polys.polytools import Poly, cancel, factor, gcd_list, discriminant from sympy.polys.rationaltools import together from sympy.polys.specialpolys import cyclotomic_poly from sympy.simplify import simplify, powsimp from sympy.utilities import public def roots_linear(f): """Returns a list of roots of a linear polynomial.""" r = -f.nth(0)/f.nth(1) dom = f.get_domain() if not dom.is_Numerical: if dom.is_Composite: r = factor(r) else: r = simplify(r) return [r] def roots_quadratic(f): """Returns a list of roots of a quadratic polynomial. If the domain is ZZ then the roots will be sorted with negatives coming before positives. The ordering will be the same for any numerical coefficients as long as the assumptions tested are correct, otherwise the ordering will not be sorted (but will be canonical). """ a, b, c = f.all_coeffs() dom = f.get_domain() def _sqrt(d): # remove squares from square root since both will be represented # in the results; a similar thing is happening in roots() but # must be duplicated here because not all quadratics are binomials co = [] other = [] for di in Mul.make_args(d): if di.is_Pow and di.exp.is_Integer and di.exp % 2 == 0: co.append(Pow(di.base, di.exp//2)) else: other.append(di) if co: d = Mul(other) co = Mul(co) return cosqrt(d) return sqrt(d) def _simplify(expr): if dom.is_Composite: return factor(expr) else: return simplify(expr) if c is S.Zero: r0, r1 = S.Zero, -b/a if not dom.is_Numerical: r1 = _simplify(r1) elif r1.is_negative: r0, r1 = r1, r0 elif b is S.Zero: r = -c/a if not dom.is_Numerical: r = _simplify(r) R = _sqrt(r) r0 = -R r1 = R else: d = b2 - 4ac A = 2a B = -b/A if not dom.is_Numerical: d = _simplify(d) B = _simplify(B) D = factor_terms(_sqrt(d)/A) r0 = B - D r1 = B + D if a.is_negative: r0, r1 = r1, r0 elif not dom.is_Numerical: r0, r1 = [expand_2arg(i) for i in (r0, r1)] return [r0, r1] def roots_cubic(f, trig=False): """Returns a list of roots of a cubic polynomial. References ========== [1] https://en.wikipedia.org/wiki/Cubic_function, General formula for roots, (accessed November 17, 2014). """ if trig: a, b, c, d = f.all_coeffs() p = (3ac - b2)/3/a2 q = (2b3 - 9abc + 27a2d)/(27a3) D = 18abcd - 4b*3d + b*2c*2 - 4ac3 - 27a*2d*2 if (D > 0) == True: rv = [] for k in range(3): rv.append(2sqrt(-p/3)cos(acos(3q/2/psqrt(-3/p))/3 - k2pi/3)) return [i - b/3/a for i in rv] _, a, b, c = f.monic().all_coeffs() if c is S.Zero: x1, x2 = roots([1, a, b], multiple=True) return [x1, S.Zero, x2] p = b - a2/3 q = c - ab/3 + 2a3/27 pon3 = p/3 aon3 = a/3 u1 = None if p is S.Zero: if q is S.Zero: return [-aon3]3 if q.is_real: if q.is_positive: u1 = -root(q, 3) elif q.is_negative: u1 = root(-q, 3) elif q is S.Zero: y1, y2 = roots([1, 0, p], multiple=True) return [tmp - aon3 for tmp in [y1, S.Zero, y2]] elif q.is_real and q.is_negative: u1 = -root(-q/2 + sqrt(q2/4 + pon33), 3) coeff = Isqrt(3)/2 if u1 is None: u1 = S(1) u2 = -S.Half + coeff u3 = -S.Half - coeff a, b, c, d = S(1), a, b, c D0 = b2 - 3ac D1 = 2b*3 - 9abc + 27a2d C = root((D1 + sqrt(D1*2 - 4D0*3))/2, 3) return [-(b + ukC + D0/C/uk)/3/a for uk in [u1, u2, u3]] u2 = u1(-S.Half + coeff) u3 = u1(-S.Half - coeff) if p is S.Zero: return [u1 - aon3, u2 - aon3, u3 - aon3] soln = [ -u1 + pon3/u1 - aon3, -u2 + pon3/u2 - aon3, -u3 + pon3/u3 - aon3 ] return soln def _roots_quartic_euler(p, q, r, a): """ Descartes-Euler solution of the quartic equation Parameters ========== p, q, r: coefficients of ``x*4 + px*2 + qx + r`` a: shift of the roots Notes ===== This is a helper function for ``roots_quartic``. Look for solutions of the form :: ``x1 = sqrt(R) - sqrt(A + Bsqrt(R))`` ``x2 = -sqrt(R) - sqrt(A - Bsqrt(R))`` ``x3 = -sqrt(R) + sqrt(A - Bsqrt(R))`` ``x4 = sqrt(R) + sqrt(A + Bsqrt(R))`` To satisfy the quartic equation one must have ``p = -2(R + A); q = -4BR; r = (R - A)2 - B2R`` so that ``R`` must satisfy the Descartes-Euler resolvent equation ``64R3 + 32pR2 + (4p*2 - 16r)R - q2 = 0`` If the resolvent does not have a rational solution, return None; in that case it is likely that the Ferrari method gives a simpler solution. Examples ======== >>> from sympy import S >>> from sympy.polys.polyroots import _roots_quartic_euler >>> p, q, r = -S(64)/5, -S(512)/125, -S(1024)/3125 >>> _roots_quartic_euler(p, q, r, S(0))[0] -sqrt(32sqrt(5)/125 + 16/5) + 4sqrt(5)/5 """ # solve the resolvent equation x = Dummy('x') eq = 64x*3 + 32px2 + (4p*2 - 16r)x - q2 xsols = list(roots(Poly(eq, x), cubics=False).keys()) xsols = [sol for sol in xsols if sol.is_rational and sol.is_nonzero] if not xsols: return None R = max(xsols) c1 = sqrt(R) B = -qc1/(4R) A = -R - p/2 c2 = sqrt(A + B) c3 = sqrt(A - B) return [c1 - c2 - a, -c1 - c3 - a, -c1 + c3 - a, c1 + c2 - a] def roots_quartic(f): r""" Returns a list of roots of a quartic polynomial. There are many references for solving quartic expressions available [1-5]. This reviewer has found that many of them require one to select from among 2 or more possible sets of solutions and that some solutions work when one is searching for real roots but don't work when searching for complex roots (though this is not always stated clearly). The following routine has been tested and found to be correct for 0, 2 or 4 complex roots. The quasisymmetric case solution [6] looks for quartics that have the form `x4 + Ax*3 + Bx*2 + Cx + D = 0` where `(C/A)*2 = D`. Although no general solution that is always applicable for all coefficients is known to this reviewer, certain conditions are tested to determine the simplest 4 expressions that can be returned: 1) `f = c + a(a*2/8 - b/2) == 0` 2) `g = d - a(a(3a*2/256 - b/16) + c/4) = 0` 3) if `f != 0` and `g != 0` and `p = -d + ac/4 - b2/12` then a) `p == 0` b) `p != 0` Examples ======== >>> from sympy import Poly, symbols, I >>> from sympy.polys.polyroots import roots_quartic >>> r = roots_quartic(Poly('x4-6x3+17x*2-26x+20')) >>> # 4 complex roots: 1+-Isqrt(3), 2+-I >>> sorted(str(tmp.evalf(n=2)) for tmp in r) ['1.0 + 1.7I', '1.0 - 1.7I', '2.0 + 1.0I', '2.0 - 1.0I'] References ========== 1. http://mathforum.org/dr.math/faq/faq.cubic.equations.html 2. https://en.wikipedia.org/wiki/Quartic_function#Summary_of_Ferrari.27s_method 3. http://planetmath.org/encyclopedia/GaloisTheoreticDerivationOfTheQuarticFormula.html 4. http://staff.bath.ac.uk/masjhd/JHD-CA.pdf 5. http://www.albmath.org/files/Math_5713.pdf 6. http://www.statemaster.com/encyclopedia/Quartic-equation 7. eqworld.ipmnet.ru/en/solutions/ae/ae0108.pdf """ _, a, b, c, d = f.monic().all_coeffs() if not d: return [S.Zero] + roots([1, a, b, c], multiple=True) elif (c/a)2 == d: x, m = f.gen, c/a g = Poly(x2 + ax + b - 2m, x) z1, z2 = roots_quadratic(g) h1 = Poly(x2 - z1x + m, x) h2 = Poly(x*2 - z2x + m, x) r1 = roots_quadratic(h1) r2 = roots_quadratic(h2) return r1 + r2 else: a2 = a*2 e = b - 3a2/8 f = _mexpand(c + a(a2/8 - b/2)) g = _mexpand(d - a(a(3a2/256 - b/16) + c/4)) aon4 = a/4 if f is S.Zero: y1, y2 = [sqrt(tmp) for tmp in roots([1, e, g], multiple=True)] return [tmp - aon4 for tmp in [-y1, -y2, y1, y2]] if g is S.Zero: y = [S.Zero] + roots([1, 0, e, f], multiple=True) return [tmp - aon4 for tmp in y] else: # Descartes-Euler method, see [7] sols = _roots_quartic_euler(e, f, g, aon4) if sols: return sols # Ferrari method, see [1, 2] a2 = a*2 e = b - 3a2/8 f = c + a(a2/8 - b/2) g = d - a(a(3a2/256 - b/16) + c/4) p = -e2/12 - g q = -e3/108 + eg/3 - f2/8 TH = Rational(1, 3) def _ans(y): w = sqrt(e + 2y) arg1 = 3e + 2y arg2 = 2f/w ans = [] for s in [-1, 1]: root = sqrt(-(arg1 + sarg2)) for t in [-1, 1]: ans.append((sw - troot)/2 - aon4) return ans # p == 0 case y1 = -5e/6 - qTH if p.is_zero: return _ans(y1) # if p != 0 then u below is not 0 root = sqrt(q2/4 + p3/27) r = -q/2 + root # or -q/2 - root u = rTH # primary root of solve(x3 - r, x) y2 = -5e/6 + u - p/u/3 if fuzzy_not(p.is_zero): return _ans(y2) # sort it out once they know the values of the coefficients return [Piecewise((a1, Eq(p, 0)), (a2, True)) for a1, a2 in zip(_ans(y1), _ans(y2))] def roots_binomial(f): """Returns a list of roots of a binomial polynomial. If the domain is ZZ then the roots will be sorted with negatives coming before positives. The ordering will be the same for any numerical coefficients as long as the assumptions tested are correct, otherwise the ordering will not be sorted (but will be canonical). """ n = f.degree() a, b = f.nth(n), f.nth(0) base = -cancel(b/a) alpha = root(base, n) if alpha.is_number: alpha = alpha.expand(complex=True) # define some parameters that will allow us to order the roots. # If the domain is ZZ this is guaranteed to return roots sorted # with reals before non-real roots and non-real sorted according # to real part and imaginary part, e.g. -1, 1, -1 + I, 2 - I neg = base.is_negative even = n % 2 == 0 if neg: if even == True and (base + 1).is_positive: big = True else: big = False # get the indices in the right order so the computed # roots will be sorted when the domain is ZZ ks = [] imax = n//2 if even: ks.append(imax) imax -= 1 if not neg: ks.append(0) for i in range(imax, 0, -1): if neg: ks.extend([i, -i]) else: ks.extend([-i, i]) if neg: ks.append(0) if big: for i in range(0, len(ks), 2): pair = ks[i: i + 2] pair = list(reversed(pair)) # compute the roots roots, d = [], 2Ipi/n for k in ks: zeta = exp(kd).expand(complex=True) roots.append((alphazeta).expand(power_base=False)) return roots def _inv_totient_estimate(m): """ Find ``(L, U)`` such that ``L <= phi^-1(m) <= U``. Examples ======== >>> from sympy.polys.polyroots import _inv_totient_estimate >>> _inv_totient_estimate(192) (192, 840) >>> _inv_totient_estimate(400) (400, 1750) """ primes = [ d + 1 for d in divisors(m) if isprime(d + 1) ] a, b = 1, 1 for p in primes: a = p b = p - 1 L = m U = int(math.ceil(m(float(a)/b))) P = p = 2 primes = [] while P <= U: p = nextprime(p) primes.append(p) P = p P //= p b = 1 for p in primes[:-1]: b = p - 1 U = int(math.ceil(m(float(P)/b))) return L, U def roots_cyclotomic(f, factor=False): """Compute roots of cyclotomic polynomials. """ L, U = _inv_totient_estimate(f.degree()) for n in range(L, U + 1): g = cyclotomic_poly(n, f.gen, polys=True) if f == g: break else: # pragma: no cover raise RuntimeError("failed to find index of a cyclotomic polynomial") roots = [] if not factor: # get the indices in the right order so the computed # roots will be sorted h = n//2 ks = [i for i in range(1, n + 1) if igcd(i, n) == 1] ks.sort(key=lambda x: (x, -1) if x <= h else (abs(x - n), 1)) d = 2Ipi/n for k in reversed(ks): roots.append(exp(kd).expand(complex=True)) else: g = Poly(f, extension=root(-1, n)) for h, _ in ordered(g.factor_list()[1]): roots.append(-h.TC()) return roots def roots_quintic(f): """ Calculate exact roots of a solvable quintic """ result = [] coeff_5, coeff_4, p, q, r, s = f.all_coeffs() # Eqn must be of the form x^5 + px^3 + qx^2 + rx + s if coeff_4: return result if coeff_5 != 1: l = [p/coeff_5, q/coeff_5, r/coeff_5, s/coeff_5] if not all(coeff.is_Rational for coeff in l): return result f = Poly(f/coeff_5) quintic = PolyQuintic(f) # Eqn standardized. Algo for solving starts here if not f.is_irreducible: return result f20 = quintic.f20 # Check if f20 has linear factors over domain Z if f20.is_irreducible: return result # Now, we know that f is solvable for _factor in f20.factor_list()[1]: if _factor[0].is_linear: theta = _factor[0].root(0) break d = discriminant(f) delta = sqrt(d) # zeta = a fifth root of unity zeta1, zeta2, zeta3, zeta4 = quintic.zeta T = quintic.T(theta, d) tol = S(1e-10) alpha = T[1] + T[2]delta alpha_bar = T[1] - T[2]delta beta = T[3] + T[4]delta beta_bar = T[3] - T[4]delta disc = alpha2 - 4beta disc_bar = alpha_bar*2 - 4beta_bar l0 = quintic.l0(theta) l1 = _quintic_simplify((-alpha + sqrt(disc)) / S(2)) l4 = _quintic_simplify((-alpha - sqrt(disc)) / S(2)) l2 = _quintic_simplify((-alpha_bar + sqrt(disc_bar)) / S(2)) l3 = _quintic_simplify((-alpha_bar - sqrt(disc_bar)) / S(2)) order = quintic.order(theta, d) test = (orderdelta.n()) - ( (l1.n() - l4.n())(l2.n() - l3.n()) ) # Comparing floats if not comp(test, 0, tol): l2, l3 = l3, l2 # Now we have correct order of l's R1 = l0 + l1zeta1 + l2zeta2 + l3zeta3 + l4zeta4 R2 = l0 + l3zeta1 + l1zeta2 + l4zeta3 + l2zeta4 R3 = l0 + l2zeta1 + l4zeta2 + l1zeta3 + l3zeta4 R4 = l0 + l4zeta1 + l3zeta2 + l2zeta3 + l1zeta4 Res = [None, [None]5, [None]5, [None]5, [None]5] Res_n = [None, [None]5, [None]5, [None]5, [None]5] sol = Symbol('sol') # Simplifying improves performance a lot for exact expressions R1 = _quintic_simplify(R1) R2 = _quintic_simplify(R2) R3 = _quintic_simplify(R3) R4 = _quintic_simplify(R4) # Solve imported here. Causing problems if imported as 'solve' # and hence the changed name from sympy.solvers.solvers import solve as _solve a, b = symbols('a b', cls=Dummy) _sol = _solve( sol*5 - a - Ib, sol) for i in range(5): _sol[i] = factor(_sol[i]) R1 = R1.as_real_imag() R2 = R2.as_real_imag() R3 = R3.as_real_imag() R4 = R4.as_real_imag() for i, currentroot in enumerate(_sol): Res[1][i] = _quintic_simplify(currentroot.subs({ a: R1[0], b: R1[1] })) Res[2][i] = _quintic_simplify(currentroot.subs({ a: R2[0], b: R2[1] })) Res[3][i] = _quintic_simplify(currentroot.subs({ a: R3[0], b: R3[1] })) Res[4][i] = _quintic_simplify(currentroot.subs({ a: R4[0], b: R4[1] })) for i in range(1, 5): for j in range(5): Res_n[i][j] = Res[i][j].n() Res[i][j] = _quintic_simplify(Res[i][j]) r1 = Res[1][0] r1_n = Res_n[1][0] for i in range(5): if comp(im(r1_nRes_n[4][i]), 0, tol): r4 = Res[4][i] break u, v = quintic.uv(theta, d) # Now we have various Res values. Each will be a list of five # values. We have to pick one r value from those five for each Res u, v = quintic.uv(theta, d) testplus = (u + vdeltasqrt(5)).n() testminus = (u - vdeltasqrt(5)).n() # Evaluated numbers suffixed with _n # We will use evaluated numbers for calculation. Much faster. r4_n = r4.n() r2 = r3 = None for i in range(5): r2temp_n = Res_n[2][i] for j in range(5): # Again storing away the exact number and using # evaluated numbers in computations r3temp_n = Res_n[3][j] if (comp((r1_nr2temp_n*2 + r4_nr3temp_n*2 - testplus).n(), 0, tol) and comp((r3temp_nr1_n*2 + r2temp_nr4_n*2 - testminus).n(), 0, tol)): r2 = Res[2][i] r3 = Res[3][j] break if r2: break # Now, we have r's so we can get roots x1 = (r1 + r2 + r3 + r4)/5 x2 = (r1zeta4 + r2zeta3 + r3zeta2 + r4zeta1)/5 x3 = (r1zeta3 + r2zeta1 + r3zeta4 + r4zeta2)/5 x4 = (r1zeta2 + r2zeta4 + r3zeta1 + r4zeta3)/5 x5 = (r1zeta1 + r2zeta2 + r3zeta3 + r4zeta4)/5 result = [x1, x2, x3, x4, x5] # Now check if solutions are distinct saw = set() for r in result: r = r.n(2) if r in saw: # Roots were identical. Abort, return [] # and fall back to usual solve return [] saw.add(r) return result def _quintic_simplify(expr): expr = powsimp(expr) expr = cancel(expr) return together(expr) def _integer_basis(poly): """Compute coefficient basis for a polynomial over integers. Returns the integer ``div`` such that substituting ``x = divy`` ``p(x) = mq(y)`` where the coefficients of ``q`` are smaller than those of ``p``. For example ``x5 + 512x + 1024 = 0`` with ``div = 4`` becomes ``y*5 + 2y + 1 = 0`` Returns the integer ``div`` or ``None`` if there is no possible scaling. Examples ======== >>> from sympy.polys import Poly >>> from sympy.abc import x >>> from sympy.polys.polyroots import _integer_basis >>> p = Poly(x*5 + 512x + 1024, x, domain='ZZ') >>> _integer_basis(p) 4 """ monoms, coeffs = list(zip(poly.terms())) monoms, = list(zip(monoms)) coeffs = list(map(abs, coeffs)) if coeffs[0] < coeffs[-1]: coeffs = list(reversed(coeffs)) n = monoms[0] monoms = [n - i for i in reversed(monoms)] else: return None monoms = monoms[:-1] coeffs = coeffs[:-1] divs = reversed(divisors(gcd_list(coeffs))[1:]) try: div = next(divs) except StopIteration: return None while True: for monom, coeff in zip(monoms, coeffs): if coeff % div*monom != 0: try: div = next(divs) except StopIteration: return None else: break else: return div def preprocess_roots(poly): """Try to get rid of symbolic coefficients from ``poly``. """ coeff = S.One poly_func = poly.func try: _, poly = poly.clear_denoms(convert=True) except DomainError: return coeff, poly poly = poly.primitive()[1] poly = poly.retract() # TODO: This is fragile. Figure out how to make this independent of construct_domain(). if poly.get_domain().is_Poly and all(c.is_term for c in poly.rep.coeffs()): poly = poly.inject() strips = list(zip(poly.monoms())) gens = list(poly.gens[1:]) base, strips = strips[0], strips[1:] for gen, strip in zip(list(gens), strips): reverse = False if strip[0] < strip[-1]: strip = reversed(strip) reverse = True ratio = None for a, b in zip(base, strip): if not a and not b: continue elif not a or not b: break elif b % a != 0: break else: _ratio = b // a if ratio is None: ratio = _ratio elif ratio != _ratio: break else: if reverse: ratio = -ratio poly = poly.eval(gen, 1) coeff = gen(-ratio) gens.remove(gen) if gens: poly = poly.eject(gens) if poly.is_univariate and poly.get_domain().is_ZZ: basis = _integer_basis(poly) if basis is not None: n = poly.degree() def func(k, coeff): return coeff//basis*(n - k[0]) poly = poly.termwise(func) coeff = basis if not isinstance(poly, poly_func): poly = poly_func(poly) return coeff, poly @public def roots(f, gens, flags): """ Computes symbolic roots of a univariate polynomial. Given a univariate polynomial f with symbolic coefficients (or a list of the polynomial's coefficients), returns a dictionary with its roots and their multiplicities. Only roots expressible via radicals will be returned. To get a complete set of roots use RootOf class or numerical methods instead. By default cubic and quartic formulas are used in the algorithm. To disable them because of unreadable output set ``cubics=False`` or ``quartics=False`` respectively. If cubic roots are real but are expressed in terms of complex numbers (casus irreducibilis [1]) the ``trig`` flag can be set to True to have the solutions returned in terms of cosine and inverse cosine functions. To get roots from a specific domain set the ``filter`` flag with one of the following specifiers: Z, Q, R, I, C. By default all roots are returned (this is equivalent to setting ``filter='C'``). By default a dictionary is returned giving a compact result in case of multiple roots. However to get a list containing all those roots set the ``multiple`` flag to True; the list will have identical roots appearing next to each other in the result. (For a given Poly, the all_roots method will give the roots in sorted numerical order.) Examples ======== >>> from sympy import Poly, roots >>> from sympy.abc import x, y >>> roots(x2 - 1, x) {-1: 1, 1: 1} >>> p = Poly(x2-1, x) >>> roots(p) {-1: 1, 1: 1} >>> p = Poly(x2-y, x, y) >>> roots(Poly(p, x)) {-sqrt(y): 1, sqrt(y): 1} >>> roots(x2 - y, x) {-sqrt(y): 1, sqrt(y): 1} >>> roots([1, 0, -1]) {-1: 1, 1: 1} References ========== .. [1] https://en.wikipedia.org/wiki/Cubic_function#Trigonometric_.28and_hyperbolic.29_method """ from sympy.polys.polytools import to_rational_coeffs flags = dict(flags) auto = flags.pop('auto', True) cubics = flags.pop('cubics', True) trig = flags.pop('trig', False) quartics = flags.pop('quartics', True) quintics = flags.pop('quintics', False) multiple = flags.pop('multiple', False) filter = flags.pop('filter', None) predicate = flags.pop('predicate', None) if isinstance(f, list): if gens: raise ValueError('redundant generators given') x = Dummy('x') poly, i = {}, len(f) - 1 for coeff in f: poly[i], i = sympify(coeff), i - 1 f = Poly(poly, x, field=True) else: try: f = Poly(f, gens, flags) if f.length == 2 and f.degree() != 1: # check for foon factors in the constant n = f.degree() npow_bases = [] others = [] expr = f.as_expr() con = expr.as_independent(gens)[0] for p in Mul.make_args(con): if p.is_Pow and not p.exp % n: npow_bases.append(p.base(p.exp/n)) else: others.append(p) if npow_bases: b = Mul(npow_bases) B = Dummy() d = roots(Poly(expr - con + B*nMul(others), gens, *flags), gens, *flags) rv = {} for k, v in d.items(): rv[k.subs(B, b)] = v return rv except GeneratorsNeeded: if multiple: return [] else: return {} if f.is_multivariate: raise PolynomialError('multivariate polynomials are not supported') def _update_dict(result, currentroot, k): if currentroot in result: result[currentroot] += k else: result[currentroot] = k def _try_decompose(f): """Find roots using functional decomposition. """ factors, roots = f.decompose(), [] for currentroot in _try_heuristics(factors[0]): roots.append(currentroot) for currentfactor in factors[1:]: previous, roots = list(roots), [] for currentroot in previous: g = currentfactor - Poly(currentroot, f.gen) for currentroot in _try_heuristics(g): roots.append(currentroot) return roots def _try_heuristics(f): """Find roots using formulas and some tricks. """ if f.is_ground: return [] if f.is_monomial: return [S(0)]f.degree() if f.length() == 2: if f.degree() == 1: return list(map(cancel, roots_linear(f))) else: return roots_binomial(f) result = [] for i in [-1, 1]: if not f.eval(i): f = f.quo(Poly(f.gen - i, f.gen)) result.append(i) break n = f.degree() if n == 1: result += list(map(cancel, roots_linear(f))) elif n == 2: result += list(map(cancel, roots_quadratic(f))) elif f.is_cyclotomic: result += roots_cyclotomic(f) elif n == 3 and cubics: result += roots_cubic(f, trig=trig) elif n == 4 and quartics: result += roots_quartic(f) elif n == 5 and quintics: result += roots_quintic(f) return result (k,), f = f.terms_gcd() if not k: zeros = {} else: zeros = {S(0): k} coeff, f = preprocess_roots(f) if auto and f.get_domain().is_Ring: f = f.to_field() rescale_x = None translate_x = None result = {} if not f.is_ground: if not f.get_domain().is_Exact: for r in f.nroots(): _update_dict(result, r, 1) elif f.degree() == 1: result[roots_linear(f)[0]] = 1 elif f.length() == 2: roots_fun = roots_quadratic if f.degree() == 2 else roots_binomial for r in roots_fun(f): _update_dict(result, r, 1) else: _, factors = Poly(f.as_expr()).factor_list() if len(factors) == 1 and f.degree() == 2: for r in roots_quadratic(f): _update_dict(result, r, 1) else: if len(factors) == 1 and factors[0][1] == 1: if f.get_domain().is_EX: res = to_rational_coeffs(f) if res: if res[0] is None: translate_x, f = res[2:] else: rescale_x, f = res[1], res[-1] result = roots(f) if not result: for currentroot in _try_decompose(f): _update_dict(result, currentroot, 1) else: for r in _try_heuristics(f): _update_dict(result, r, 1) else: for currentroot in _try_decompose(f): _update_dict(result, currentroot, 1) else: for currentfactor, k in factors: for r in _try_heuristics(Poly(currentfactor, f.gen, field=True)): _update_dict(result, r, k) if coeff is not S.One: _result, result, = result, {} for currentroot, k in _result.items(): result[coeffcurrentroot] = k result.update(zeros) if filter not in [None, 'C']: handlers = { 'Z': lambda r: r.is_Integer, 'Q': lambda r: r.is_Rational, 'R': lambda r: r.is_real, 'I': lambda r: r.is_imaginary, } try: query = handlers[filter] except KeyError: raise ValueError("Invalid filter: %s" % filter) for zero in dict(result).keys(): if not query(zero): del result[zero] if predicate is not None: for zero in dict(result).keys(): if not predicate(zero): del result[zero] if rescale_x: result1 = {} for k, v in result.items(): result1[krescale_x] = v result = result1 if translate_x: result1 = {} for k, v in result.items(): result1[k + translate_x] = v result = result1 if not multiple: return result else: zeros = [] for zero in ordered(result): zeros.extend([zero]result[zero]) return zeros def root_factors(f, gens, args): """ Returns all factors of a univariate polynomial. Examples ======== >>> from sympy.abc import x, y >>> from sympy.polys.polyroots import root_factors >>> root_factors(x2 - y, x) [x - sqrt(y), x + sqrt(y)] """ args = dict(args) filter = args.pop('filter', None) F = Poly(f, gens, args) if not F.is_Poly: return [f] if F.is_multivariate: raise ValueError('multivariate polynomials are not supported') x = F.gens[0] zeros = roots(F, filter=filter) if not zeros: factors = [F] else: factors, N = [], 0 for r, n in ordered(zeros.items()): factors, N = factors + [Poly(x - r, x)]n, N + n if N < F.degree(): G = reduce(lambda p, q: p*q, factors) factors.append(F.quo(G)) if not isinstance(f, Poly): factors = [ f.as_expr() for f in factors ] return factors
1f9af2ea3c618f461ab67594a80a1f3b1304b2782f62e73d9b8de2486b31227b	"""Arithmetics for dense recursive polynomials in ``K[x]`` or ``K[X]``. """ from __future__ import print_function, division from sympy.core.compatibility import range from sympy.polys.densebasic import ( dup_slice, dup_LC, dmp_LC, dup_degree, dmp_degree, dup_strip, dmp_strip, dmp_zero_p, dmp_zero, dmp_one_p, dmp_one, dmp_ground, dmp_zeros) from sympy.polys.polyerrors import (ExactQuotientFailed, PolynomialDivisionFailed) def dup_add_term(f, c, i, K): """ Add ``cxi`` to ``f`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_add_term(x2 - 1, ZZ(2), 4) 2x4 + x2 - 1 """ if not c: return f n = len(f) m = n - i - 1 if i == n - 1: return dup_strip([f[0] + c] + f[1:]) else: if i >= n: return [c] + [K.zero](i - n) + f else: return f[:m] + [f[m] + c] + f[m + 1:] def dmp_add_term(f, c, i, u, K): """ Add ``c(x_2..x_u)x_0*i`` to ``f`` in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_add_term(xy + 1, 2, 2) 2x2 + xy + 1 """ if not u: return dup_add_term(f, c, i, K) v = u - 1 if dmp_zero_p(c, v): return f n = len(f) m = n - i - 1 if i == n - 1: return dmp_strip([dmp_add(f[0], c, v, K)] + f[1:], u) else: if i >= n: return [c] + dmp_zeros(i - n, v, K) + f else: return f[:m] + [dmp_add(f[m], c, v, K)] + f[m + 1:] def dup_sub_term(f, c, i, K): """ Subtract ``cxi`` from ``f`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_sub_term(2x4 + x2 - 1, ZZ(2), 4) x*2 - 1 """ if not c: return f n = len(f) m = n - i - 1 if i == n - 1: return dup_strip([f[0] - c] + f[1:]) else: if i >= n: return [-c] + [K.zero](i - n) + f else: return f[:m] + [f[m] - c] + f[m + 1:] def dmp_sub_term(f, c, i, u, K): """ Subtract ``c(x_2..x_u)x_0i`` from ``f`` in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_sub_term(2x*2 + xy + 1, 2, 2) xy + 1 """ if not u: return dup_add_term(f, -c, i, K) v = u - 1 if dmp_zero_p(c, v): return f n = len(f) m = n - i - 1 if i == n - 1: return dmp_strip([dmp_sub(f[0], c, v, K)] + f[1:], u) else: if i >= n: return [dmp_neg(c, v, K)] + dmp_zeros(i - n, v, K) + f else: return f[:m] + [dmp_sub(f[m], c, v, K)] + f[m + 1:] def dup_mul_term(f, c, i, K): """ Multiply ``f`` by ``cxi`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_mul_term(x2 - 1, ZZ(3), 2) 3x4 - 3x*2 """ if not c or not f: return [] else: return [ cf c for cf in f ] + [K.zero]i def dmp_mul_term(f, c, i, u, K): """ Multiply ``f`` by ``c(x_2..x_u)x_0i`` in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_mul_term(x2y + x, 3y, 2) 3x4y*2 + 3x*3y """ if not u: return dup_mul_term(f, c, i, K) v = u - 1 if dmp_zero_p(f, u): return f if dmp_zero_p(c, v): return dmp_zero(u) else: return [ dmp_mul(cf, c, v, K) for cf in f ] + dmp_zeros(i, v, K) def dup_add_ground(f, c, K): """ Add an element of the ground domain to ``f``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_add_ground(x*3 + 2x*2 + 3x + 4, ZZ(4)) x*3 + 2x*2 + 3x + 8 """ return dup_add_term(f, c, 0, K) def dmp_add_ground(f, c, u, K): """ Add an element of the ground domain to ``f``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_add_ground(x*3 + 2x*2 + 3x + 4, ZZ(4)) x*3 + 2x*2 + 3x + 8 """ return dmp_add_term(f, dmp_ground(c, u - 1), 0, u, K) def dup_sub_ground(f, c, K): """ Subtract an element of the ground domain from ``f``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_sub_ground(x*3 + 2x*2 + 3x + 4, ZZ(4)) x*3 + 2x*2 + 3x """ return dup_sub_term(f, c, 0, K) def dmp_sub_ground(f, c, u, K): """ Subtract an element of the ground domain from ``f``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_sub_ground(x*3 + 2x*2 + 3x + 4, ZZ(4)) x*3 + 2x*2 + 3x """ return dmp_sub_term(f, dmp_ground(c, u - 1), 0, u, K) def dup_mul_ground(f, c, K): """ Multiply ``f`` by a constant value in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_mul_ground(x*2 + 2x - 1, ZZ(3)) 3x2 + 6x - 3 """ if not c or not f: return [] else: return [ cf * c for cf in f ] def dmp_mul_ground(f, c, u, K): """ Multiply ``f`` by a constant value in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_mul_ground(2x + 2y, ZZ(3)) 6x + 6y """ if not u: return dup_mul_ground(f, c, K) v = u - 1 return [ dmp_mul_ground(cf, c, v, K) for cf in f ] def dup_quo_ground(f, c, K): """ Quotient by a constant in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ, QQ >>> R, x = ring("x", ZZ) >>> R.dup_quo_ground(3x2 + 2, ZZ(2)) x2 + 1 >>> R, x = ring("x", QQ) >>> R.dup_quo_ground(3x*2 + 2, QQ(2)) 3/2x*2 + 1 """ if not c: raise ZeroDivisionError('polynomial division') if not f: return f if K.is_Field: return [ K.quo(cf, c) for cf in f ] else: return [ cf // c for cf in f ] def dmp_quo_ground(f, c, u, K): """ Quotient by a constant in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ, QQ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_quo_ground(2x*2y + 3x, ZZ(2)) x2y + x >>> R, x,y = ring("x,y", QQ) >>> R.dmp_quo_ground(2x2y + 3x, QQ(2)) x2y + 3/2x """ if not u: return dup_quo_ground(f, c, K) v = u - 1 return [ dmp_quo_ground(cf, c, v, K) for cf in f ] def dup_exquo_ground(f, c, K): """ Exact quotient by a constant in ``K[x]``. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x = ring("x", QQ) >>> R.dup_exquo_ground(x2 + 2, QQ(2)) 1/2x2 + 1 """ if not c: raise ZeroDivisionError('polynomial division') if not f: return f return [ K.exquo(cf, c) for cf in f ] def dmp_exquo_ground(f, c, u, K): """ Exact quotient by a constant in ``K[X]``. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x,y = ring("x,y", QQ) >>> R.dmp_exquo_ground(x2y + 2x, QQ(2)) 1/2x2y + x """ if not u: return dup_exquo_ground(f, c, K) v = u - 1 return [ dmp_exquo_ground(cf, c, v, K) for cf in f ] def dup_lshift(f, n, K): """ Efficiently multiply ``f`` by ``xn`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_lshift(x2 + 1, 2) x4 + x2 """ if not f: return f else: return f + [K.zero]n def dup_rshift(f, n, K): """ Efficiently divide ``f`` by ``xn`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_rshift(x4 + x2, 2) x2 + 1 >>> R.dup_rshift(x4 + x2 + 2, 2) x2 + 1 """ return f[:-n] def dup_abs(f, K): """ Make all coefficients positive in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_abs(x2 - 1) x2 + 1 """ return [ K.abs(coeff) for coeff in f ] def dmp_abs(f, u, K): """ Make all coefficients positive in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_abs(x2y - x) x*2y + x """ if not u: return dup_abs(f, K) v = u - 1 return [ dmp_abs(cf, v, K) for cf in f ] def dup_neg(f, K): """ Negate a polynomial in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_neg(x2 - 1) -x2 + 1 """ return [ -coeff for coeff in f ] def dmp_neg(f, u, K): """ Negate a polynomial in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_neg(x*2y - x) -x*2y + x """ if not u: return dup_neg(f, K) v = u - 1 return [ dmp_neg(cf, v, K) for cf in f ] def dup_add(f, g, K): """ Add dense polynomials in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_add(x2 - 1, x - 2) x2 + x - 3 """ if not f: return g if not g: return f df = dup_degree(f) dg = dup_degree(g) if df == dg: return dup_strip([ a + b for a, b in zip(f, g) ]) else: k = abs(df - dg) if df > dg: h, f = f[:k], f[k:] else: h, g = g[:k], g[k:] return h + [ a + b for a, b in zip(f, g) ] def dmp_add(f, g, u, K): """ Add dense polynomials in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_add(x2 + y, x2y + x) x2y + x2 + x + y """ if not u: return dup_add(f, g, K) df = dmp_degree(f, u) if df < 0: return g dg = dmp_degree(g, u) if dg < 0: return f v = u - 1 if df == dg: return dmp_strip([ dmp_add(a, b, v, K) for a, b in zip(f, g) ], u) else: k = abs(df - dg) if df > dg: h, f = f[:k], f[k:] else: h, g = g[:k], g[k:] return h + [ dmp_add(a, b, v, K) for a, b in zip(f, g) ] def dup_sub(f, g, K): """ Subtract dense polynomials in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_sub(x2 - 1, x - 2) x2 - x + 1 """ if not f: return dup_neg(g, K) if not g: return f df = dup_degree(f) dg = dup_degree(g) if df == dg: return dup_strip([ a - b for a, b in zip(f, g) ]) else: k = abs(df - dg) if df > dg: h, f = f[:k], f[k:] else: h, g = dup_neg(g[:k], K), g[k:] return h + [ a - b for a, b in zip(f, g) ] def dmp_sub(f, g, u, K): """ Subtract dense polynomials in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_sub(x2 + y, x*2y + x) -x*2y + x*2 - x + y """ if not u: return dup_sub(f, g, K) df = dmp_degree(f, u) if df < 0: return dmp_neg(g, u, K) dg = dmp_degree(g, u) if dg < 0: return f v = u - 1 if df == dg: return dmp_strip([ dmp_sub(a, b, v, K) for a, b in zip(f, g) ], u) else: k = abs(df - dg) if df > dg: h, f = f[:k], f[k:] else: h, g = dmp_neg(g[:k], u, K), g[k:] return h + [ dmp_sub(a, b, v, K) for a, b in zip(f, g) ] def dup_add_mul(f, g, h, K): """ Returns ``f + gh`` where ``f, g, h`` are in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_add_mul(x*2 - 1, x - 2, x + 2) 2x*2 - 5 """ return dup_add(f, dup_mul(g, h, K), K) def dmp_add_mul(f, g, h, u, K): """ Returns ``f + gh`` where ``f, g, h`` are in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_add_mul(x*2 + y, x, x + 2) 2x*2 + 2x + y """ return dmp_add(f, dmp_mul(g, h, u, K), u, K) def dup_sub_mul(f, g, h, K): """ Returns ``f - gh`` where ``f, g, h`` are in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_sub_mul(x2 - 1, x - 2, x + 2) 3 """ return dup_sub(f, dup_mul(g, h, K), K) def dmp_sub_mul(f, g, h, u, K): """ Returns ``f - gh`` where ``f, g, h`` are in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_sub_mul(x*2 + y, x, x + 2) -2x + y """ return dmp_sub(f, dmp_mul(g, h, u, K), u, K) def dup_mul(f, g, K): """ Multiply dense polynomials in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_mul(x - 2, x + 2) x*2 - 4 """ if f == g: return dup_sqr(f, K) if not (f and g): return [] df = dup_degree(f) dg = dup_degree(g) n = max(df, dg) + 1 if n < 100: h = [] for i in range(0, df + dg + 1): coeff = K.zero for j in range(max(0, i - dg), min(df, i) + 1): coeff += f[j]g[i - j] h.append(coeff) return dup_strip(h) else: # Use Karatsuba's algorithm (divide and conquer), see e.g.: # Joris van der Hoeven, Relax But Don't Be Too Lazy, # J. Symbolic Computation, 11 (2002), section 3.1.1. n2 = n//2 fl, gl = dup_slice(f, 0, n2, K), dup_slice(g, 0, n2, K) fh = dup_rshift(dup_slice(f, n2, n, K), n2, K) gh = dup_rshift(dup_slice(g, n2, n, K), n2, K) lo, hi = dup_mul(fl, gl, K), dup_mul(fh, gh, K) mid = dup_mul(dup_add(fl, fh, K), dup_add(gl, gh, K), K) mid = dup_sub(mid, dup_add(lo, hi, K), K) return dup_add(dup_add(lo, dup_lshift(mid, n2, K), K), dup_lshift(hi, 2n2, K), K) def dmp_mul(f, g, u, K): """ Multiply dense polynomials in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_mul(xy + 1, x) x*2y + x """ if not u: return dup_mul(f, g, K) if f == g: return dmp_sqr(f, u, K) df = dmp_degree(f, u) if df < 0: return f dg = dmp_degree(g, u) if dg < 0: return g h, v = [], u - 1 for i in range(0, df + dg + 1): coeff = dmp_zero(v) for j in range(max(0, i - dg), min(df, i) + 1): coeff = dmp_add(coeff, dmp_mul(f[j], g[i - j], v, K), v, K) h.append(coeff) return dmp_strip(h, u) def dup_sqr(f, K): """ Square dense polynomials in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_sqr(x2 + 1) x4 + 2x2 + 1 """ df, h = len(f) - 1, [] for i in range(0, 2df + 1): c = K.zero jmin = max(0, i - df) jmax = min(i, df) n = jmax - jmin + 1 jmax = jmin + n // 2 - 1 for j in range(jmin, jmax + 1): c += f[j]f[i - j] c += c if n & 1: elem = f[jmax + 1] c += elem2 h.append(c) return dup_strip(h) def dmp_sqr(f, u, K): """ Square dense polynomials in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_sqr(x2 + xy + y2) x4 + 2x3y + 3x2y*2 + 2xy3 + y4 """ if not u: return dup_sqr(f, K) df = dmp_degree(f, u) if df < 0: return f h, v = [], u - 1 for i in range(0, 2df + 1): c = dmp_zero(v) jmin = max(0, i - df) jmax = min(i, df) n = jmax - jmin + 1 jmax = jmin + n // 2 - 1 for j in range(jmin, jmax + 1): c = dmp_add(c, dmp_mul(f[j], f[i - j], v, K), v, K) c = dmp_mul_ground(c, K(2), v, K) if n & 1: elem = dmp_sqr(f[jmax + 1], v, K) c = dmp_add(c, elem, v, K) h.append(c) return dmp_strip(h, u) def dup_pow(f, n, K): """ Raise ``f`` to the ``n``-th power in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_pow(x - 2, 3) x*3 - 6x*2 + 12x - 8 """ if not n: return [K.one] if n < 0: raise ValueError("can't raise polynomial to a negative power") if n == 1 or not f or f == [K.one]: return f g = [K.one] while True: n, m = n//2, n if m % 2: g = dup_mul(g, f, K) if not n: break f = dup_sqr(f, K) return g def dmp_pow(f, n, u, K): """ Raise ``f`` to the ``n``-th power in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_pow(xy + 1, 3) x3y*3 + 3x*2y*2 + 3xy + 1 """ if not u: return dup_pow(f, n, K) if not n: return dmp_one(u, K) if n < 0: raise ValueError("can't raise polynomial to a negative power") if n == 1 or dmp_zero_p(f, u) or dmp_one_p(f, u, K): return f g = dmp_one(u, K) while True: n, m = n//2, n if m & 1: g = dmp_mul(g, f, u, K) if not n: break f = dmp_sqr(f, u, K) return g def dup_pdiv(f, g, K): """ Polynomial pseudo-division in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_pdiv(x2 + 1, 2x - 4) (2x + 4, 20) """ df = dup_degree(f) dg = dup_degree(g) q, r, dr = [], f, df if not g: raise ZeroDivisionError("polynomial division") elif df < dg: return q, r N = df - dg + 1 lc_g = dup_LC(g, K) while True: lc_r = dup_LC(r, K) j, N = dr - dg, N - 1 Q = dup_mul_ground(q, lc_g, K) q = dup_add_term(Q, lc_r, j, K) R = dup_mul_ground(r, lc_g, K) G = dup_mul_term(g, lc_r, j, K) r = dup_sub(R, G, K) _dr, dr = dr, dup_degree(r) if dr < dg: break elif not (dr < _dr): raise PolynomialDivisionFailed(f, g, K) c = lc_gN q = dup_mul_ground(q, c, K) r = dup_mul_ground(r, c, K) return q, r def dup_prem(f, g, K): """ Polynomial pseudo-remainder in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_prem(x2 + 1, 2x - 4) 20 """ df = dup_degree(f) dg = dup_degree(g) r, dr = f, df if not g: raise ZeroDivisionError("polynomial division") elif df < dg: return r N = df - dg + 1 lc_g = dup_LC(g, K) while True: lc_r = dup_LC(r, K) j, N = dr - dg, N - 1 R = dup_mul_ground(r, lc_g, K) G = dup_mul_term(g, lc_r, j, K) r = dup_sub(R, G, K) _dr, dr = dr, dup_degree(r) if dr < dg: break elif not (dr < _dr): raise PolynomialDivisionFailed(f, g, K) return dup_mul_ground(r, lc_gN, K) def dup_pquo(f, g, K): """ Polynomial exact pseudo-quotient in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_pquo(x2 - 1, 2x - 2) 2x + 2 >>> R.dup_pquo(x*2 + 1, 2x - 4) 2x + 4 """ return dup_pdiv(f, g, K)[0] def dup_pexquo(f, g, K): """ Polynomial pseudo-quotient in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_pexquo(x2 - 1, 2x - 2) 2x + 2 >>> R.dup_pexquo(x2 + 1, 2x - 4) Traceback (most recent call last): ... ExactQuotientFailed: [2, -4] does not divide [1, 0, 1] """ q, r = dup_pdiv(f, g, K) if not r: return q else: raise ExactQuotientFailed(f, g) def dmp_pdiv(f, g, u, K): """ Polynomial pseudo-division in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_pdiv(x*2 + xy, 2x + 2) (2x + 2y - 2, -4y + 4) """ if not u: return dup_pdiv(f, g, K) df = dmp_degree(f, u) dg = dmp_degree(g, u) if dg < 0: raise ZeroDivisionError("polynomial division") q, r, dr = dmp_zero(u), f, df if df < dg: return q, r N = df - dg + 1 lc_g = dmp_LC(g, K) while True: lc_r = dmp_LC(r, K) j, N = dr - dg, N - 1 Q = dmp_mul_term(q, lc_g, 0, u, K) q = dmp_add_term(Q, lc_r, j, u, K) R = dmp_mul_term(r, lc_g, 0, u, K) G = dmp_mul_term(g, lc_r, j, u, K) r = dmp_sub(R, G, u, K) _dr, dr = dr, dmp_degree(r, u) if dr < dg: break elif not (dr < _dr): raise PolynomialDivisionFailed(f, g, K) c = dmp_pow(lc_g, N, u - 1, K) q = dmp_mul_term(q, c, 0, u, K) r = dmp_mul_term(r, c, 0, u, K) return q, r def dmp_prem(f, g, u, K): """ Polynomial pseudo-remainder in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_prem(x*2 + xy, 2x + 2) -4y + 4 """ if not u: return dup_prem(f, g, K) df = dmp_degree(f, u) dg = dmp_degree(g, u) if dg < 0: raise ZeroDivisionError("polynomial division") r, dr = f, df if df < dg: return r N = df - dg + 1 lc_g = dmp_LC(g, K) while True: lc_r = dmp_LC(r, K) j, N = dr - dg, N - 1 R = dmp_mul_term(r, lc_g, 0, u, K) G = dmp_mul_term(g, lc_r, j, u, K) r = dmp_sub(R, G, u, K) _dr, dr = dr, dmp_degree(r, u) if dr < dg: break elif not (dr < _dr): raise PolynomialDivisionFailed(f, g, K) c = dmp_pow(lc_g, N, u - 1, K) return dmp_mul_term(r, c, 0, u, K) def dmp_pquo(f, g, u, K): """ Polynomial exact pseudo-quotient in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = x*2 + xy >>> g = 2x + 2y >>> h = 2x + 2 >>> R.dmp_pquo(f, g) 2x >>> R.dmp_pquo(f, h) 2x + 2y - 2 """ return dmp_pdiv(f, g, u, K)[0] def dmp_pexquo(f, g, u, K): """ Polynomial pseudo-quotient in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = x*2 + xy >>> g = 2x + 2y >>> h = 2x + 2 >>> R.dmp_pexquo(f, g) 2x >>> R.dmp_pexquo(f, h) Traceback (most recent call last): ... ExactQuotientFailed: [[2], [2]] does not divide [[1], [1, 0], []] """ q, r = dmp_pdiv(f, g, u, K) if dmp_zero_p(r, u): return q else: raise ExactQuotientFailed(f, g) def dup_rr_div(f, g, K): """ Univariate division with remainder over a ring. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_rr_div(x*2 + 1, 2x - 4) (0, x2 + 1) """ df = dup_degree(f) dg = dup_degree(g) q, r, dr = [], f, df if not g: raise ZeroDivisionError("polynomial division") elif df < dg: return q, r lc_g = dup_LC(g, K) while True: lc_r = dup_LC(r, K) if lc_r % lc_g: break c = K.exquo(lc_r, lc_g) j = dr - dg q = dup_add_term(q, c, j, K) h = dup_mul_term(g, c, j, K) r = dup_sub(r, h, K) _dr, dr = dr, dup_degree(r) if dr < dg: break elif not (dr < _dr): raise PolynomialDivisionFailed(f, g, K) return q, r def dmp_rr_div(f, g, u, K): """ Multivariate division with remainder over a ring. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_rr_div(x2 + xy, 2x + 2) (0, x*2 + xy) """ if not u: return dup_rr_div(f, g, K) df = dmp_degree(f, u) dg = dmp_degree(g, u) if dg < 0: raise ZeroDivisionError("polynomial division") q, r, dr = dmp_zero(u), f, df if df < dg: return q, r lc_g, v = dmp_LC(g, K), u - 1 while True: lc_r = dmp_LC(r, K) c, R = dmp_rr_div(lc_r, lc_g, v, K) if not dmp_zero_p(R, v): break j = dr - dg q = dmp_add_term(q, c, j, u, K) h = dmp_mul_term(g, c, j, u, K) r = dmp_sub(r, h, u, K) _dr, dr = dr, dmp_degree(r, u) if dr < dg: break elif not (dr < _dr): raise PolynomialDivisionFailed(f, g, K) return q, r def dup_ff_div(f, g, K): """ Polynomial division with remainder over a field. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x = ring("x", QQ) >>> R.dup_ff_div(x*2 + 1, 2x - 4) (1/2x + 1, 5) """ df = dup_degree(f) dg = dup_degree(g) q, r, dr = [], f, df if not g: raise ZeroDivisionError("polynomial division") elif df < dg: return q, r lc_g = dup_LC(g, K) while True: lc_r = dup_LC(r, K) c = K.exquo(lc_r, lc_g) j = dr - dg q = dup_add_term(q, c, j, K) h = dup_mul_term(g, c, j, K) r = dup_sub(r, h, K) _dr, dr = dr, dup_degree(r) if dr < dg: break elif not (dr < _dr): raise PolynomialDivisionFailed(f, g, K) return q, r def dmp_ff_div(f, g, u, K): """ Polynomial division with remainder over a field. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x,y = ring("x,y", QQ) >>> R.dmp_ff_div(x2 + xy, 2x + 2) (1/2x + 1/2y - 1/2, -y + 1) """ if not u: return dup_ff_div(f, g, K) df = dmp_degree(f, u) dg = dmp_degree(g, u) if dg < 0: raise ZeroDivisionError("polynomial division") q, r, dr = dmp_zero(u), f, df if df < dg: return q, r lc_g, v = dmp_LC(g, K), u - 1 while True: lc_r = dmp_LC(r, K) c, R = dmp_ff_div(lc_r, lc_g, v, K) if not dmp_zero_p(R, v): break j = dr - dg q = dmp_add_term(q, c, j, u, K) h = dmp_mul_term(g, c, j, u, K) r = dmp_sub(r, h, u, K) _dr, dr = dr, dmp_degree(r, u) if dr < dg: break elif not (dr < _dr): raise PolynomialDivisionFailed(f, g, K) return q, r def dup_div(f, g, K): """ Polynomial division with remainder in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ, QQ >>> R, x = ring("x", ZZ) >>> R.dup_div(x2 + 1, 2x - 4) (0, x2 + 1) >>> R, x = ring("x", QQ) >>> R.dup_div(x2 + 1, 2x - 4) (1/2x + 1, 5) """ if K.is_Field: return dup_ff_div(f, g, K) else: return dup_rr_div(f, g, K) def dup_rem(f, g, K): """ Returns polynomial remainder in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ, QQ >>> R, x = ring("x", ZZ) >>> R.dup_rem(x*2 + 1, 2x - 4) x2 + 1 >>> R, x = ring("x", QQ) >>> R.dup_rem(x2 + 1, 2x - 4) 5 """ return dup_div(f, g, K)[1] def dup_quo(f, g, K): """ Returns exact polynomial quotient in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ, QQ >>> R, x = ring("x", ZZ) >>> R.dup_quo(x2 + 1, 2x - 4) 0 >>> R, x = ring("x", QQ) >>> R.dup_quo(x*2 + 1, 2x - 4) 1/2x + 1 """ return dup_div(f, g, K)[0] def dup_exquo(f, g, K): """ Returns polynomial quotient in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_exquo(x2 - 1, x - 1) x + 1 >>> R.dup_exquo(x2 + 1, 2x - 4) Traceback (most recent call last): ... ExactQuotientFailed: [2, -4] does not divide [1, 0, 1] """ q, r = dup_div(f, g, K) if not r: return q else: raise ExactQuotientFailed(f, g) def dmp_div(f, g, u, K): """ Polynomial division with remainder in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ, QQ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_div(x*2 + xy, 2x + 2) (0, x2 + xy) >>> R, x,y = ring("x,y", QQ) >>> R.dmp_div(x*2 + xy, 2x + 2) (1/2x + 1/2y - 1/2, -y + 1) """ if K.is_Field: return dmp_ff_div(f, g, u, K) else: return dmp_rr_div(f, g, u, K) def dmp_rem(f, g, u, K): """ Returns polynomial remainder in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ, QQ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_rem(x2 + xy, 2x + 2) x2 + xy >>> R, x,y = ring("x,y", QQ) >>> R.dmp_rem(x*2 + xy, 2x + 2) -y + 1 """ return dmp_div(f, g, u, K)[1] def dmp_quo(f, g, u, K): """ Returns exact polynomial quotient in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ, QQ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_quo(x2 + xy, 2x + 2) 0 >>> R, x,y = ring("x,y", QQ) >>> R.dmp_quo(x2 + xy, 2x + 2) 1/2x + 1/2y - 1/2 """ return dmp_div(f, g, u, K)[0] def dmp_exquo(f, g, u, K): """ Returns polynomial quotient in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = x2 + xy >>> g = x + y >>> h = 2x + 2 >>> R.dmp_exquo(f, g) x >>> R.dmp_exquo(f, h) Traceback (most recent call last): ... ExactQuotientFailed: [[2], [2]] does not divide [[1], [1, 0], []] """ q, r = dmp_div(f, g, u, K) if dmp_zero_p(r, u): return q else: raise ExactQuotientFailed(f, g) def dup_max_norm(f, K): """ Returns maximum norm of a polynomial in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_max_norm(-x2 + 2x - 3) 3 """ if not f: return K.zero else: return max(dup_abs(f, K)) def dmp_max_norm(f, u, K): """ Returns maximum norm of a polynomial in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_max_norm(2xy - x - 3) 3 """ if not u: return dup_max_norm(f, K) v = u - 1 return max([ dmp_max_norm(c, v, K) for c in f ]) def dup_l1_norm(f, K): """ Returns l1 norm of a polynomial in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_l1_norm(2x3 - 3x*2 + 1) 6 """ if not f: return K.zero else: return sum(dup_abs(f, K)) def dmp_l1_norm(f, u, K): """ Returns l1 norm of a polynomial in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_l1_norm(2xy - x - 3) 6 """ if not u: return dup_l1_norm(f, K) v = u - 1 return sum([ dmp_l1_norm(c, v, K) for c in f ]) def dup_expand(polys, K): """ Multiply together several polynomials in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_expand([x2 - 1, x, 2]) 2x*3 - 2x """ if not polys: return [K.one] f = polys[0] for g in polys[1:]: f = dup_mul(f, g, K) return f def dmp_expand(polys, u, K): """ Multiply together several polynomials in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_expand([x2 + y2, x + 1]) x3 + x2 + xy2 + y*2 """ if not polys: return dmp_one(u, K) f = polys[0] for g in polys[1:]: f = dmp_mul(f, g, u, K) return f
c4653040a7f00b9c950c28f59732e579f7c83b5f57a969324dc9cf7b25fb3205	"""Dense univariate polynomials with coefficients in Galois fields. """ from __future__ import print_function, division from random import uniform from math import ceil as _ceil, sqrt as _sqrt from sympy.core.compatibility import SYMPY_INTS, range from sympy.core.mul import prod from sympy.ntheory import factorint from sympy.polys.polyconfig import query from sympy.polys.polyerrors import ExactQuotientFailed from sympy.polys.polyutils import _sort_factors def gf_crt(U, M, K=None): """ Chinese Remainder Theorem. Given a set of integer residues ``u_0,...,u_n`` and a set of co-prime integer moduli ``m_0,...,m_n``, returns an integer ``u``, such that ``u = u_i mod m_i`` for ``i = ``0,...,n``. Examples ======== Consider a set of residues ``U = [49, 76, 65]`` and a set of moduli ``M = [99, 97, 95]``. Then we have:: >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_crt >>> from sympy.ntheory.modular import solve_congruence >>> gf_crt([49, 76, 65], [99, 97, 95], ZZ) 639985 This is the correct result because:: >>> [639985 % m for m in [99, 97, 95]] [49, 76, 65] Note: this is a low-level routine with no error checking. See Also ======== sympy.ntheory.modular.crt : a higher level crt routine sympy.ntheory.modular.solve_congruence """ p = prod(M, start=K.one) v = K.zero for u, m in zip(U, M): e = p // m s, _, _ = K.gcdex(e, m) v += e(us % m) return v % p def gf_crt1(M, K): """ First part of the Chinese Remainder Theorem. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_crt1 >>> gf_crt1([99, 97, 95], ZZ) (912285, [9215, 9405, 9603], [62, 24, 12]) """ E, S = [], [] p = prod(M, start=K.one) for m in M: E.append(p // m) S.append(K.gcdex(E[-1], m)[0] % m) return p, E, S def gf_crt2(U, M, p, E, S, K): """ Second part of the Chinese Remainder Theorem. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_crt2 >>> U = [49, 76, 65] >>> M = [99, 97, 95] >>> p = 912285 >>> E = [9215, 9405, 9603] >>> S = [62, 24, 12] >>> gf_crt2(U, M, p, E, S, ZZ) 639985 """ v = K.zero for u, m, e, s in zip(U, M, E, S): v += e(us % m) return v % p def gf_int(a, p): """ Coerce ``a mod p`` to an integer in the range ``[-p/2, p/2]``. Examples ======== >>> from sympy.polys.galoistools import gf_int >>> gf_int(2, 7) 2 >>> gf_int(5, 7) -2 """ if a <= p // 2: return a else: return a - p def gf_degree(f): """ Return the leading degree of ``f``. Examples ======== >>> from sympy.polys.galoistools import gf_degree >>> gf_degree([1, 1, 2, 0]) 3 >>> gf_degree([]) -1 """ return len(f) - 1 def gf_LC(f, K): """ Return the leading coefficient of ``f``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_LC >>> gf_LC([3, 0, 1], ZZ) 3 """ if not f: return K.zero else: return f[0] def gf_TC(f, K): """ Return the trailing coefficient of ``f``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_TC >>> gf_TC([3, 0, 1], ZZ) 1 """ if not f: return K.zero else: return f[-1] def gf_strip(f): """ Remove leading zeros from ``f``. Examples ======== >>> from sympy.polys.galoistools import gf_strip >>> gf_strip([0, 0, 0, 3, 0, 1]) [3, 0, 1] """ if not f or f[0]: return f k = 0 for coeff in f: if coeff: break else: k += 1 return f[k:] def gf_trunc(f, p): """ Reduce all coefficients modulo ``p``. Examples ======== >>> from sympy.polys.galoistools import gf_trunc >>> gf_trunc([7, -2, 3], 5) [2, 3, 3] """ return gf_strip([ a % p for a in f ]) def gf_normal(f, p, K): """ Normalize all coefficients in ``K``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_normal >>> gf_normal([5, 10, 21, -3], 5, ZZ) [1, 2] """ return gf_trunc(list(map(K, f)), p) def gf_from_dict(f, p, K): """ Create a ``GF(p)[x]`` polynomial from a dict. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_from_dict >>> gf_from_dict({10: ZZ(4), 4: ZZ(33), 0: ZZ(-1)}, 5, ZZ) [4, 0, 0, 0, 0, 0, 3, 0, 0, 0, 4] """ n, h = max(f.keys()), [] if isinstance(n, SYMPY_INTS): for k in range(n, -1, -1): h.append(f.get(k, K.zero) % p) else: (n,) = n for k in range(n, -1, -1): h.append(f.get((k,), K.zero) % p) return gf_trunc(h, p) def gf_to_dict(f, p, symmetric=True): """ Convert a ``GF(p)[x]`` polynomial to a dict. Examples ======== >>> from sympy.polys.galoistools import gf_to_dict >>> gf_to_dict([4, 0, 0, 0, 0, 0, 3, 0, 0, 0, 4], 5) {0: -1, 4: -2, 10: -1} >>> gf_to_dict([4, 0, 0, 0, 0, 0, 3, 0, 0, 0, 4], 5, symmetric=False) {0: 4, 4: 3, 10: 4} """ n, result = gf_degree(f), {} for k in range(0, n + 1): if symmetric: a = gf_int(f[n - k], p) else: a = f[n - k] if a: result[k] = a return result def gf_from_int_poly(f, p): """ Create a ``GF(p)[x]`` polynomial from ``Z[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_from_int_poly >>> gf_from_int_poly([7, -2, 3], 5) [2, 3, 3] """ return gf_trunc(f, p) def gf_to_int_poly(f, p, symmetric=True): """ Convert a ``GF(p)[x]`` polynomial to ``Z[x]``. Examples ======== >>> from sympy.polys.galoistools import gf_to_int_poly >>> gf_to_int_poly([2, 3, 3], 5) [2, -2, -2] >>> gf_to_int_poly([2, 3, 3], 5, symmetric=False) [2, 3, 3] """ if symmetric: return [ gf_int(c, p) for c in f ] else: return f def gf_neg(f, p, K): """ Negate a polynomial in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_neg >>> gf_neg([3, 2, 1, 0], 5, ZZ) [2, 3, 4, 0] """ return [ -coeff % p for coeff in f ] def gf_add_ground(f, a, p, K): """ Compute ``f + a`` where ``f`` in ``GF(p)[x]`` and ``a`` in ``GF(p)``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_add_ground >>> gf_add_ground([3, 2, 4], 2, 5, ZZ) [3, 2, 1] """ if not f: a = a % p else: a = (f[-1] + a) % p if len(f) > 1: return f[:-1] + [a] if not a: return [] else: return [a] def gf_sub_ground(f, a, p, K): """ Compute ``f - a`` where ``f`` in ``GF(p)[x]`` and ``a`` in ``GF(p)``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_sub_ground >>> gf_sub_ground([3, 2, 4], 2, 5, ZZ) [3, 2, 2] """ if not f: a = -a % p else: a = (f[-1] - a) % p if len(f) > 1: return f[:-1] + [a] if not a: return [] else: return [a] def gf_mul_ground(f, a, p, K): """ Compute ``f * a`` where ``f`` in ``GF(p)[x]`` and ``a`` in ``GF(p)``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_mul_ground >>> gf_mul_ground([3, 2, 4], 2, 5, ZZ) [1, 4, 3] """ if not a: return [] else: return [ (ab) % p for b in f ] def gf_quo_ground(f, a, p, K): """ Compute ``f/a`` where ``f`` in ``GF(p)[x]`` and ``a`` in ``GF(p)``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_quo_ground >>> gf_quo_ground(ZZ.map([3, 2, 4]), ZZ(2), 5, ZZ) [4, 1, 2] """ return gf_mul_ground(f, K.invert(a, p), p, K) def gf_add(f, g, p, K): """ Add polynomials in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_add >>> gf_add([3, 2, 4], [2, 2, 2], 5, ZZ) [4, 1] """ if not f: return g if not g: return f df = gf_degree(f) dg = gf_degree(g) if df == dg: return gf_strip([ (a + b) % p for a, b in zip(f, g) ]) else: k = abs(df - dg) if df > dg: h, f = f[:k], f[k:] else: h, g = g[:k], g[k:] return h + [ (a + b) % p for a, b in zip(f, g) ] def gf_sub(f, g, p, K): """ Subtract polynomials in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_sub >>> gf_sub([3, 2, 4], [2, 2, 2], 5, ZZ) [1, 0, 2] """ if not g: return f if not f: return gf_neg(g, p, K) df = gf_degree(f) dg = gf_degree(g) if df == dg: return gf_strip([ (a - b) % p for a, b in zip(f, g) ]) else: k = abs(df - dg) if df > dg: h, f = f[:k], f[k:] else: h, g = gf_neg(g[:k], p, K), g[k:] return h + [ (a - b) % p for a, b in zip(f, g) ] def gf_mul(f, g, p, K): """ Multiply polynomials in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_mul >>> gf_mul([3, 2, 4], [2, 2, 2], 5, ZZ) [1, 0, 3, 2, 3] """ df = gf_degree(f) dg = gf_degree(g) dh = df + dg h = [0](dh + 1) for i in range(0, dh + 1): coeff = K.zero for j in range(max(0, i - dg), min(i, df) + 1): coeff += f[j]g[i - j] h[i] = coeff % p return gf_strip(h) def gf_sqr(f, p, K): """ Square polynomials in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_sqr >>> gf_sqr([3, 2, 4], 5, ZZ) [4, 2, 3, 1, 1] """ df = gf_degree(f) dh = 2df h = [0](dh + 1) for i in range(0, dh + 1): coeff = K.zero jmin = max(0, i - df) jmax = min(i, df) n = jmax - jmin + 1 jmax = jmin + n // 2 - 1 for j in range(jmin, jmax + 1): coeff += f[j]f[i - j] coeff += coeff if n & 1: elem = f[jmax + 1] coeff += elem*2 h[i] = coeff % p return gf_strip(h) def gf_add_mul(f, g, h, p, K): """ Returns ``f + gh`` where ``f``, ``g``, ``h`` in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_add_mul >>> gf_add_mul([3, 2, 4], [2, 2, 2], [1, 4], 5, ZZ) [2, 3, 2, 2] """ return gf_add(f, gf_mul(g, h, p, K), p, K) def gf_sub_mul(f, g, h, p, K): """ Compute ``f - gh`` where ``f``, ``g``, ``h`` in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_sub_mul >>> gf_sub_mul([3, 2, 4], [2, 2, 2], [1, 4], 5, ZZ) [3, 3, 2, 1] """ return gf_sub(f, gf_mul(g, h, p, K), p, K) def gf_expand(F, p, K): """ Expand results of :func:`factor` in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_expand >>> gf_expand([([3, 2, 4], 1), ([2, 2], 2), ([3, 1], 3)], 5, ZZ) [4, 3, 0, 3, 0, 1, 4, 1] """ if type(F) is tuple: lc, F = F else: lc = K.one g = [lc] for f, k in F: f = gf_pow(f, k, p, K) g = gf_mul(g, f, p, K) return g def gf_div(f, g, p, K): """ Division with remainder in ``GF(p)[x]``. Given univariate polynomials ``f`` and ``g`` with coefficients in a finite field with ``p`` elements, returns polynomials ``q`` and ``r`` (quotient and remainder) such that ``f = qg + r``. Consider polynomials ``x3 + x + 1`` and ``x2 + x`` in GF(2):: >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_div, gf_add_mul >>> gf_div(ZZ.map([1, 0, 1, 1]), ZZ.map([1, 1, 0]), 2, ZZ) ([1, 1], [1]) As result we obtained quotient ``x + 1`` and remainder ``1``, thus:: >>> gf_add_mul(ZZ.map([1]), ZZ.map([1, 1]), ZZ.map([1, 1, 0]), 2, ZZ) [1, 0, 1, 1] References ========== .. [1] [Monagan93]_ .. [2] [Gathen99]_ """ df = gf_degree(f) dg = gf_degree(g) if not g: raise ZeroDivisionError("polynomial division") elif df < dg: return [], f inv = K.invert(g[0], p) h, dq, dr = list(f), df - dg, dg - 1 for i in range(0, df + 1): coeff = h[i] for j in range(max(0, dg - i), min(df - i, dr) + 1): coeff -= h[i + j - dg] * g[dg - j] if i <= dq: coeff = inv h[i] = coeff % p return h[:dq + 1], gf_strip(h[dq + 1:]) def gf_rem(f, g, p, K): """ Compute polynomial remainder in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_rem >>> gf_rem(ZZ.map([1, 0, 1, 1]), ZZ.map([1, 1, 0]), 2, ZZ) [1] """ return gf_div(f, g, p, K)[1] def gf_quo(f, g, p, K): """ Compute exact quotient in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_quo >>> gf_quo(ZZ.map([1, 0, 1, 1]), ZZ.map([1, 1, 0]), 2, ZZ) [1, 1] >>> gf_quo(ZZ.map([1, 0, 3, 2, 3]), ZZ.map([2, 2, 2]), 5, ZZ) [3, 2, 4] """ df = gf_degree(f) dg = gf_degree(g) if not g: raise ZeroDivisionError("polynomial division") elif df < dg: return [] inv = K.invert(g[0], p) h, dq, dr = f[:], df - dg, dg - 1 for i in range(0, dq + 1): coeff = h[i] for j in range(max(0, dg - i), min(df - i, dr) + 1): coeff -= h[i + j - dg] g[dg - j] h[i] = (coeff * inv) % p return h[:dq + 1] def gf_exquo(f, g, p, K): """ Compute polynomial quotient in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_exquo >>> gf_exquo(ZZ.map([1, 0, 3, 2, 3]), ZZ.map([2, 2, 2]), 5, ZZ) [3, 2, 4] >>> gf_exquo(ZZ.map([1, 0, 1, 1]), ZZ.map([1, 1, 0]), 2, ZZ) Traceback (most recent call last): ... ExactQuotientFailed: [1, 1, 0] does not divide [1, 0, 1, 1] """ q, r = gf_div(f, g, p, K) if not r: return q else: raise ExactQuotientFailed(f, g) def gf_lshift(f, n, K): """ Efficiently multiply ``f`` by ``x*n``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_lshift >>> gf_lshift([3, 2, 4], 4, ZZ) [3, 2, 4, 0, 0, 0, 0] """ if not f: return f else: return f + [K.zero]n def gf_rshift(f, n, K): """ Efficiently divide ``f`` by ``xn``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_rshift >>> gf_rshift([1, 2, 3, 4, 0], 3, ZZ) ([1, 2], [3, 4, 0]) """ if not n: return f, [] else: return f[:-n], f[-n:] def gf_pow(f, n, p, K): """ Compute ``fn`` in ``GF(p)[x]`` using repeated squaring. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_pow >>> gf_pow([3, 2, 4], 3, 5, ZZ) [2, 4, 4, 2, 2, 1, 4] """ if not n: return [K.one] elif n == 1: return f elif n == 2: return gf_sqr(f, p, K) h = [K.one] while True: if n & 1: h = gf_mul(h, f, p, K) n -= 1 n >>= 1 if not n: break f = gf_sqr(f, p, K) return h def gf_frobenius_monomial_base(g, p, K): """ return the list of ``x*(ip) mod g in Z_p`` for ``i = 0, .., n - 1`` where ``n = gf_degree(g)`` Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_frobenius_monomial_base >>> g = ZZ.map([1, 0, 2, 1]) >>> gf_frobenius_monomial_base(g, 5, ZZ) [[1], [4, 4, 2], [1, 2]] """ n = gf_degree(g) if n == 0: return [] b = [0]n b[0] = [1] if p < n: for i in range(1, n): mon = gf_lshift(b[i - 1], p, K) b[i] = gf_rem(mon, g, p, K) elif n > 1: b[1] = gf_pow_mod([K.one, K.zero], p, g, p, K) for i in range(2, n): b[i] = gf_mul(b[i - 1], b[1], p, K) b[i] = gf_rem(b[i], g, p, K) return b def gf_frobenius_map(f, g, b, p, K): """ compute gf_pow_mod(f, p, g, p, K) using the Frobenius map Parameters ========== f, g : polynomials in ``GF(p)[x]`` b : frobenius monomial base p : prime number K : domain Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_frobenius_monomial_base, gf_frobenius_map >>> f = ZZ.map([2, 1 , 0, 1]) >>> g = ZZ.map([1, 0, 2, 1]) >>> p = 5 >>> b = gf_frobenius_monomial_base(g, p, ZZ) >>> r = gf_frobenius_map(f, g, b, p, ZZ) >>> gf_frobenius_map(f, g, b, p, ZZ) [4, 0, 3] """ m = gf_degree(g) if gf_degree(f) >= m: f = gf_rem(f, g, p, K) if not f: return [] n = gf_degree(f) sf = [f[-1]] for i in range(1, n + 1): v = gf_mul_ground(b[i], f[n - i], p, K) sf = gf_add(sf, v, p, K) return sf def _gf_pow_pnm1d2(f, n, g, b, p, K): """ utility function for ``gf_edf_zassenhaus`` Compute ``f((pn - 1) // 2)`` in ``GF(p)[x]/(g)`` ``f((pn - 1) // 2) = (ff*p...f(pn - 1))((p - 1) // 2)`` """ f = gf_rem(f, g, p, K) h = f r = f for i in range(1, n): h = gf_frobenius_map(h, g, b, p, K) r = gf_mul(r, h, p, K) r = gf_rem(r, g, p, K) res = gf_pow_mod(r, (p - 1)//2, g, p, K) return res def gf_pow_mod(f, n, g, p, K): """ Compute ``fn`` in ``GF(p)[x]/(g)`` using repeated squaring. Given polynomials ``f`` and ``g`` in ``GF(p)[x]`` and a non-negative integer ``n``, efficiently computes ``fn (mod g)`` i.e. the remainder of ``fn`` from division by ``g``, using the repeated squaring algorithm. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_pow_mod >>> gf_pow_mod(ZZ.map([3, 2, 4]), 3, ZZ.map([1, 1]), 5, ZZ) [] References ========== .. [1] [Gathen99]_ """ if not n: return [K.one] elif n == 1: return gf_rem(f, g, p, K) elif n == 2: return gf_rem(gf_sqr(f, p, K), g, p, K) h = [K.one] while True: if n & 1: h = gf_mul(h, f, p, K) h = gf_rem(h, g, p, K) n -= 1 n >>= 1 if not n: break f = gf_sqr(f, p, K) f = gf_rem(f, g, p, K) return h def gf_gcd(f, g, p, K): """ Euclidean Algorithm in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_gcd >>> gf_gcd(ZZ.map([3, 2, 4]), ZZ.map([2, 2, 3]), 5, ZZ) [1, 3] """ while g: f, g = g, gf_rem(f, g, p, K) return gf_monic(f, p, K)[1] def gf_lcm(f, g, p, K): """ Compute polynomial LCM in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_lcm >>> gf_lcm(ZZ.map([3, 2, 4]), ZZ.map([2, 2, 3]), 5, ZZ) [1, 2, 0, 4] """ if not f or not g: return [] h = gf_quo(gf_mul(f, g, p, K), gf_gcd(f, g, p, K), p, K) return gf_monic(h, p, K)[1] def gf_cofactors(f, g, p, K): """ Compute polynomial GCD and cofactors in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_cofactors >>> gf_cofactors(ZZ.map([3, 2, 4]), ZZ.map([2, 2, 3]), 5, ZZ) ([1, 3], [3, 3], [2, 1]) """ if not f and not g: return ([], [], []) h = gf_gcd(f, g, p, K) return (h, gf_quo(f, h, p, K), gf_quo(g, h, p, K)) def gf_gcdex(f, g, p, K): """ Extended Euclidean Algorithm in ``GF(p)[x]``. Given polynomials ``f`` and ``g`` in ``GF(p)[x]``, computes polynomials ``s``, ``t`` and ``h``, such that ``h = gcd(f, g)`` and ``sf + tg = h``. The typical application of EEA is solving polynomial diophantine equations. Consider polynomials ``f = (x + 7) (x + 1)``, ``g = (x + 7) (x2 + 1)`` in ``GF(11)[x]``. Application of Extended Euclidean Algorithm gives:: >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_gcdex, gf_mul, gf_add >>> s, t, g = gf_gcdex(ZZ.map([1, 8, 7]), ZZ.map([1, 7, 1, 7]), 11, ZZ) >>> s, t, g ([5, 6], [6], [1, 7]) As result we obtained polynomials ``s = 5x + 6`` and ``t = 6``, and additionally ``gcd(f, g) = x + 7``. This is correct because:: >>> S = gf_mul(s, ZZ.map([1, 8, 7]), 11, ZZ) >>> T = gf_mul(t, ZZ.map([1, 7, 1, 7]), 11, ZZ) >>> gf_add(S, T, 11, ZZ) == [1, 7] True References ========== .. [1] [Gathen99]_ """ if not (f or g): return [K.one], [], [] p0, r0 = gf_monic(f, p, K) p1, r1 = gf_monic(g, p, K) if not f: return [], [K.invert(p1, p)], r1 if not g: return [K.invert(p0, p)], [], r0 s0, s1 = [K.invert(p0, p)], [] t0, t1 = [], [K.invert(p1, p)] while True: Q, R = gf_div(r0, r1, p, K) if not R: break (lc, r1), r0 = gf_monic(R, p, K), r1 inv = K.invert(lc, p) s = gf_sub_mul(s0, s1, Q, p, K) t = gf_sub_mul(t0, t1, Q, p, K) s1, s0 = gf_mul_ground(s, inv, p, K), s1 t1, t0 = gf_mul_ground(t, inv, p, K), t1 return s1, t1, r1 def gf_monic(f, p, K): """ Compute LC and a monic polynomial in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_monic >>> gf_monic(ZZ.map([3, 2, 4]), 5, ZZ) (3, [1, 4, 3]) """ if not f: return K.zero, [] else: lc = f[0] if K.is_one(lc): return lc, list(f) else: return lc, gf_quo_ground(f, lc, p, K) def gf_diff(f, p, K): """ Differentiate polynomial in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_diff >>> gf_diff([3, 2, 4], 5, ZZ) [1, 2] """ df = gf_degree(f) h, n = [K.zero]df, df for coeff in f[:-1]: coeff = K(n) coeff %= p if coeff: h[df - n] = coeff n -= 1 return gf_strip(h) def gf_eval(f, a, p, K): """ Evaluate ``f(a)`` in ``GF(p)`` using Horner scheme. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_eval >>> gf_eval([3, 2, 4], 2, 5, ZZ) 0 """ result = K.zero for c in f: result = a result += c result %= p return result def gf_multi_eval(f, A, p, K): """ Evaluate ``f(a)`` for ``a`` in ``[a_1, ..., a_n]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_multi_eval >>> gf_multi_eval([3, 2, 4], [0, 1, 2, 3, 4], 5, ZZ) [4, 4, 0, 2, 0] """ return [ gf_eval(f, a, p, K) for a in A ] def gf_compose(f, g, p, K): """ Compute polynomial composition ``f(g)`` in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_compose >>> gf_compose([3, 2, 4], [2, 2, 2], 5, ZZ) [2, 4, 0, 3, 0] """ if len(g) <= 1: return gf_strip([gf_eval(f, gf_LC(g, K), p, K)]) if not f: return [] h = [f[0]] for c in f[1:]: h = gf_mul(h, g, p, K) h = gf_add_ground(h, c, p, K) return h def gf_compose_mod(g, h, f, p, K): """ Compute polynomial composition ``g(h)`` in ``GF(p)[x]/(f)``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_compose_mod >>> gf_compose_mod(ZZ.map([3, 2, 4]), ZZ.map([2, 2, 2]), ZZ.map([4, 3]), 5, ZZ) [4] """ if not g: return [] comp = [g[0]] for a in g[1:]: comp = gf_mul(comp, h, p, K) comp = gf_add_ground(comp, a, p, K) comp = gf_rem(comp, f, p, K) return comp def gf_trace_map(a, b, c, n, f, p, K): """ Compute polynomial trace map in ``GF(p)[x]/(f)``. Given a polynomial ``f`` in ``GF(p)[x]``, polynomials ``a``, ``b``, ``c`` in the quotient ring ``GF(p)[x]/(f)`` such that ``b = ct (mod f)`` for some positive power ``t`` of ``p``, and a positive integer ``n``, returns a mapping:: a -> atn, a + at + at2 + ... + atn (mod f) In factorization context, ``b = xp mod f`` and ``c = x mod f``. This way we can efficiently compute trace polynomials in equal degree factorization routine, much faster than with other methods, like iterated Frobenius algorithm, for large degrees. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_trace_map >>> gf_trace_map([1, 2], [4, 4], [1, 1], 4, [3, 2, 4], 5, ZZ) ([1, 3], [1, 3]) References ========== .. [1] [Gathen92]_ """ u = gf_compose_mod(a, b, f, p, K) v = b if n & 1: U = gf_add(a, u, p, K) V = b else: U = a V = c n >>= 1 while n: u = gf_add(u, gf_compose_mod(u, v, f, p, K), p, K) v = gf_compose_mod(v, v, f, p, K) if n & 1: U = gf_add(U, gf_compose_mod(u, V, f, p, K), p, K) V = gf_compose_mod(v, V, f, p, K) n >>= 1 return gf_compose_mod(a, V, f, p, K), U def _gf_trace_map(f, n, g, b, p, K): """ utility for ``gf_edf_shoup`` """ f = gf_rem(f, g, p, K) h = f r = f for i in range(1, n): h = gf_frobenius_map(h, g, b, p, K) r = gf_add(r, h, p, K) r = gf_rem(r, g, p, K) return r def gf_random(n, p, K): """ Generate a random polynomial in ``GF(p)[x]`` of degree ``n``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_random >>> gf_random(10, 5, ZZ) #doctest: +SKIP [1, 2, 3, 2, 1, 1, 1, 2, 0, 4, 2] """ return [K.one] + [ K(int(uniform(0, p))) for i in range(0, n) ] def gf_irreducible(n, p, K): """ Generate random irreducible polynomial of degree ``n`` in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_irreducible >>> gf_irreducible(10, 5, ZZ) #doctest: +SKIP [1, 4, 2, 2, 3, 2, 4, 1, 4, 0, 4] """ while True: f = gf_random(n, p, K) if gf_irreducible_p(f, p, K): return f def gf_irred_p_ben_or(f, p, K): """ Ben-Or's polynomial irreducibility test over finite fields. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_irred_p_ben_or >>> gf_irred_p_ben_or(ZZ.map([1, 4, 2, 2, 3, 2, 4, 1, 4, 0, 4]), 5, ZZ) True >>> gf_irred_p_ben_or(ZZ.map([3, 2, 4]), 5, ZZ) False """ n = gf_degree(f) if n <= 1: return True _, f = gf_monic(f, p, K) if n < 5: H = h = gf_pow_mod([K.one, K.zero], p, f, p, K) for i in range(0, n//2): g = gf_sub(h, [K.one, K.zero], p, K) if gf_gcd(f, g, p, K) == [K.one]: h = gf_compose_mod(h, H, f, p, K) else: return False else: b = gf_frobenius_monomial_base(f, p, K) H = h = gf_frobenius_map([K.one, K.zero], f, b, p, K) for i in range(0, n//2): g = gf_sub(h, [K.one, K.zero], p, K) if gf_gcd(f, g, p, K) == [K.one]: h = gf_frobenius_map(h, f, b, p, K) else: return False return True def gf_irred_p_rabin(f, p, K): """ Rabin's polynomial irreducibility test over finite fields. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_irred_p_rabin >>> gf_irred_p_rabin(ZZ.map([1, 4, 2, 2, 3, 2, 4, 1, 4, 0, 4]), 5, ZZ) True >>> gf_irred_p_rabin(ZZ.map([3, 2, 4]), 5, ZZ) False """ n = gf_degree(f) if n <= 1: return True _, f = gf_monic(f, p, K) x = [K.one, K.zero] indices = { n//d for d in factorint(n) } b = gf_frobenius_monomial_base(f, p, K) h = b[1] for i in range(1, n): if i in indices: g = gf_sub(h, x, p, K) if gf_gcd(f, g, p, K) != [K.one]: return False h = gf_frobenius_map(h, f, b, p, K) return h == x _irred_methods = { 'ben-or': gf_irred_p_ben_or, 'rabin': gf_irred_p_rabin, } def gf_irreducible_p(f, p, K): """ Test irreducibility of a polynomial ``f`` in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_irreducible_p >>> gf_irreducible_p(ZZ.map([1, 4, 2, 2, 3, 2, 4, 1, 4, 0, 4]), 5, ZZ) True >>> gf_irreducible_p(ZZ.map([3, 2, 4]), 5, ZZ) False """ method = query('GF_IRRED_METHOD') if method is not None: irred = _irred_methods[method](f, p, K) else: irred = gf_irred_p_rabin(f, p, K) return irred def gf_sqf_p(f, p, K): """ Return ``True`` if ``f`` is square-free in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_sqf_p >>> gf_sqf_p(ZZ.map([3, 2, 4]), 5, ZZ) True >>> gf_sqf_p(ZZ.map([2, 4, 4, 2, 2, 1, 4]), 5, ZZ) False """ _, f = gf_monic(f, p, K) if not f: return True else: return gf_gcd(f, gf_diff(f, p, K), p, K) == [K.one] def gf_sqf_part(f, p, K): """ Return square-free part of a ``GF(p)[x]`` polynomial. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_sqf_part >>> gf_sqf_part(ZZ.map([1, 1, 3, 0, 1, 0, 2, 2, 1]), 5, ZZ) [1, 4, 3] """ _, sqf = gf_sqf_list(f, p, K) g = [K.one] for f, _ in sqf: g = gf_mul(g, f, p, K) return g def gf_sqf_list(f, p, K, all=False): """ Return the square-free decomposition of a ``GF(p)[x]`` polynomial. Given a polynomial ``f`` in ``GF(p)[x]``, returns the leading coefficient of ``f`` and a square-free decomposition ``f_1e_1 f_2e_2 ... f_ke_k`` such that all ``f_i`` are monic polynomials and ``(f_i, f_j)`` for ``i != j`` are co-prime and ``e_1 ... e_k`` are given in increasing order. All trivial terms (i.e. ``f_i = 1``) aren't included in the output. Consider polynomial ``f = x11 + 1`` over ``GF(11)[x]``:: >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import ( ... gf_from_dict, gf_diff, gf_sqf_list, gf_pow, ... ) ... # doctest: +NORMALIZE_WHITESPACE >>> f = gf_from_dict({11: ZZ(1), 0: ZZ(1)}, 11, ZZ) Note that ``f'(x) = 0``:: >>> gf_diff(f, 11, ZZ) [] This phenomenon doesn't happen in characteristic zero. However we can still compute square-free decomposition of ``f`` using ``gf_sqf()``:: >>> gf_sqf_list(f, 11, ZZ) (1, [([1, 1], 11)]) We obtained factorization ``f = (x + 1)11``. This is correct because:: >>> gf_pow([1, 1], 11, 11, ZZ) == f True References ========== .. [1] [Geddes92]_ """ n, sqf, factors, r = 1, False, [], int(p) lc, f = gf_monic(f, p, K) if gf_degree(f) < 1: return lc, [] while True: F = gf_diff(f, p, K) if F != []: g = gf_gcd(f, F, p, K) h = gf_quo(f, g, p, K) i = 1 while h != [K.one]: G = gf_gcd(g, h, p, K) H = gf_quo(h, G, p, K) if gf_degree(H) > 0: factors.append((H, in)) g, h, i = gf_quo(g, G, p, K), G, i + 1 if g == [K.one]: sqf = True else: f = g if not sqf: d = gf_degree(f) // r for i in range(0, d + 1): f[i] = f[ir] f, n = f[:d + 1], nr else: break if all: raise ValueError("'all=True' is not supported yet") return lc, factors def gf_Qmatrix(f, p, K): """ Calculate Berlekamp's ``Q`` matrix. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_Qmatrix >>> gf_Qmatrix([3, 2, 4], 5, ZZ) [[1, 0], [3, 4]] >>> gf_Qmatrix([1, 0, 0, 0, 1], 5, ZZ) [[1, 0, 0, 0], [0, 4, 0, 0], [0, 0, 1, 0], [0, 0, 0, 4]] """ n, r = gf_degree(f), int(p) q = [K.one] + [K.zero](n - 1) Q = [list(q)] + [[]](n - 1) for i in range(1, (n - 1)r + 1): qq, c = [(-q[-1]f[-1]) % p], q[-1] for j in range(1, n): qq.append((q[j - 1] - cf[-j - 1]) % p) if not (i % r): Q[i//r] = list(qq) q = qq return Q def gf_Qbasis(Q, p, K): """ Compute a basis of the kernel of ``Q``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_Qmatrix, gf_Qbasis >>> gf_Qbasis(gf_Qmatrix([1, 0, 0, 0, 1], 5, ZZ), 5, ZZ) [[1, 0, 0, 0], [0, 0, 1, 0]] >>> gf_Qbasis(gf_Qmatrix([3, 2, 4], 5, ZZ), 5, ZZ) [[1, 0]] """ Q, n = [ list(q) for q in Q ], len(Q) for k in range(0, n): Q[k][k] = (Q[k][k] - K.one) % p for k in range(0, n): for i in range(k, n): if Q[k][i]: break else: continue inv = K.invert(Q[k][i], p) for j in range(0, n): Q[j][i] = (Q[j][i]inv) % p for j in range(0, n): t = Q[j][k] Q[j][k] = Q[j][i] Q[j][i] = t for i in range(0, n): if i != k: q = Q[k][i] for j in range(0, n): Q[j][i] = (Q[j][i] - Q[j][k]q) % p for i in range(0, n): for j in range(0, n): if i == j: Q[i][j] = (K.one - Q[i][j]) % p else: Q[i][j] = (-Q[i][j]) % p basis = [] for q in Q: if any(q): basis.append(q) return basis def gf_berlekamp(f, p, K): """ Factor a square-free ``f`` in ``GF(p)[x]`` for small ``p``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_berlekamp >>> gf_berlekamp([1, 0, 0, 0, 1], 5, ZZ) [[1, 0, 2], [1, 0, 3]] """ Q = gf_Qmatrix(f, p, K) V = gf_Qbasis(Q, p, K) for i, v in enumerate(V): V[i] = gf_strip(list(reversed(v))) factors = [f] for k in range(1, len(V)): for f in list(factors): s = K.zero while s < p: g = gf_sub_ground(V[k], s, p, K) h = gf_gcd(f, g, p, K) if h != [K.one] and h != f: factors.remove(f) f = gf_quo(f, h, p, K) factors.extend([f, h]) if len(factors) == len(V): return _sort_factors(factors, multiple=False) s += K.one return _sort_factors(factors, multiple=False) def gf_ddf_zassenhaus(f, p, K): """ Cantor-Zassenhaus: Deterministic Distinct Degree Factorization Given a monic square-free polynomial ``f`` in ``GF(p)[x]``, computes partial distinct degree factorization ``f_1 ... f_d`` of ``f`` where ``deg(f_i) != deg(f_j)`` for ``i != j``. The result is returned as a list of pairs ``(f_i, e_i)`` where ``deg(f_i) > 0`` and ``e_i > 0`` is an argument to the equal degree factorization routine. Consider the polynomial ``x15 - 1`` in ``GF(11)[x]``:: >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_from_dict >>> f = gf_from_dict({15: ZZ(1), 0: ZZ(-1)}, 11, ZZ) Distinct degree factorization gives:: >>> from sympy.polys.galoistools import gf_ddf_zassenhaus >>> gf_ddf_zassenhaus(f, 11, ZZ) [([1, 0, 0, 0, 0, 10], 1), ([1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1], 2)] which means ``x15 - 1 = (x5 - 1) (x10 + x5 + 1)``. To obtain factorization into irreducibles, use equal degree factorization procedure (EDF) with each of the factors. References ========== .. [1] [Gathen99]_ .. [2] [Geddes92]_ """ i, g, factors = 1, [K.one, K.zero], [] b = gf_frobenius_monomial_base(f, p, K) while 2i <= gf_degree(f): g = gf_frobenius_map(g, f, b, p, K) h = gf_gcd(f, gf_sub(g, [K.one, K.zero], p, K), p, K) if h != [K.one]: factors.append((h, i)) f = gf_quo(f, h, p, K) g = gf_rem(g, f, p, K) b = gf_frobenius_monomial_base(f, p, K) i += 1 if f != [K.one]: return factors + [(f, gf_degree(f))] else: return factors def gf_edf_zassenhaus(f, n, p, K): """ Cantor-Zassenhaus: Probabilistic Equal Degree Factorization Given a monic square-free polynomial ``f`` in ``GF(p)[x]`` and an integer ``n``, such that ``n`` divides ``deg(f)``, returns all irreducible factors ``f_1,...,f_d`` of ``f``, each of degree ``n``. EDF procedure gives complete factorization over Galois fields. Consider the square-free polynomial ``f = x3 + x2 + x + 1`` in ``GF(5)[x]``. Let's compute its irreducible factors of degree one:: >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_edf_zassenhaus >>> gf_edf_zassenhaus([1,1,1,1], 1, 5, ZZ) [[1, 1], [1, 2], [1, 3]] References ========== .. [1] [Gathen99]_ .. [2] [Geddes92]_ """ factors = [f] if gf_degree(f) <= n: return factors N = gf_degree(f) // n if p != 2: b = gf_frobenius_monomial_base(f, p, K) while len(factors) < N: r = gf_random(2n - 1, p, K) if p == 2: h = r for i in range(0, 2(nN - 1)): r = gf_pow_mod(r, 2, f, p, K) h = gf_add(h, r, p, K) g = gf_gcd(f, h, p, K) else: h = _gf_pow_pnm1d2(r, n, f, b, p, K) g = gf_gcd(f, gf_sub_ground(h, K.one, p, K), p, K) if g != [K.one] and g != f: factors = gf_edf_zassenhaus(g, n, p, K) \ + gf_edf_zassenhaus(gf_quo(f, g, p, K), n, p, K) return _sort_factors(factors, multiple=False) def gf_ddf_shoup(f, p, K): """ Kaltofen-Shoup: Deterministic Distinct Degree Factorization Given a monic square-free polynomial ``f`` in ``GF(p)[x]``, computes partial distinct degree factorization ``f_1,...,f_d`` of ``f`` where ``deg(f_i) != deg(f_j)`` for ``i != j``. The result is returned as a list of pairs ``(f_i, e_i)`` where ``deg(f_i) > 0`` and ``e_i > 0`` is an argument to the equal degree factorization routine. This algorithm is an improved version of Zassenhaus algorithm for large ``deg(f)`` and modulus ``p`` (especially for ``deg(f) ~ lg(p)``). Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_ddf_shoup, gf_from_dict >>> f = gf_from_dict({6: ZZ(1), 5: ZZ(-1), 4: ZZ(1), 3: ZZ(1), 1: ZZ(-1)}, 3, ZZ) >>> gf_ddf_shoup(f, 3, ZZ) [([1, 1, 0], 1), ([1, 1, 0, 1, 2], 2)] References ========== .. [1] [Kaltofen98]_ .. [2] [Shoup95]_ .. [3] [Gathen92]_ """ n = gf_degree(f) k = int(_ceil(_sqrt(n//2))) b = gf_frobenius_monomial_base(f, p, K) h = gf_frobenius_map([K.one, K.zero], f, b, p, K) # U[i] = x(pi) U = [[K.one, K.zero], h] + [K.zero](k - 1) for i in range(2, k + 1): U[i] = gf_frobenius_map(U[i-1], f, b, p, K) h, U = U[k], U[:k] # V[i] = x(p(k(i+1))) V = [h] + [K.zero](k - 1) for i in range(1, k): V[i] = gf_compose_mod(V[i - 1], h, f, p, K) factors = [] for i, v in enumerate(V): h, j = [K.one], k - 1 for u in U: g = gf_sub(v, u, p, K) h = gf_mul(h, g, p, K) h = gf_rem(h, f, p, K) g = gf_gcd(f, h, p, K) f = gf_quo(f, g, p, K) for u in reversed(U): h = gf_sub(v, u, p, K) F = gf_gcd(g, h, p, K) if F != [K.one]: factors.append((F, k(i + 1) - j)) g, j = gf_quo(g, F, p, K), j - 1 if f != [K.one]: factors.append((f, gf_degree(f))) return factors def gf_edf_shoup(f, n, p, K): """ Gathen-Shoup: Probabilistic Equal Degree Factorization Given a monic square-free polynomial ``f`` in ``GF(p)[x]`` and integer ``n`` such that ``n`` divides ``deg(f)``, returns all irreducible factors ``f_1,...,f_d`` of ``f``, each of degree ``n``. This is a complete factorization over Galois fields. This algorithm is an improved version of Zassenhaus algorithm for large ``deg(f)`` and modulus ``p`` (especially for ``deg(f) ~ lg(p)``). Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_edf_shoup >>> gf_edf_shoup(ZZ.map([1, 2837, 2277]), 1, 2917, ZZ) [[1, 852], [1, 1985]] References ========== .. [1] [Shoup91]_ .. [2] [Gathen92]_ """ N, q = gf_degree(f), int(p) if not N: return [] if N <= n: return [f] factors, x = [f], [K.one, K.zero] r = gf_random(N - 1, p, K) if p == 2: h = gf_pow_mod(x, q, f, p, K) H = gf_trace_map(r, h, x, n - 1, f, p, K)[1] h1 = gf_gcd(f, H, p, K) h2 = gf_quo(f, h1, p, K) factors = gf_edf_shoup(h1, n, p, K) \ + gf_edf_shoup(h2, n, p, K) else: b = gf_frobenius_monomial_base(f, p, K) H = _gf_trace_map(r, n, f, b, p, K) h = gf_pow_mod(H, (q - 1)//2, f, p, K) h1 = gf_gcd(f, h, p, K) h2 = gf_gcd(f, gf_sub_ground(h, K.one, p, K), p, K) h3 = gf_quo(f, gf_mul(h1, h2, p, K), p, K) factors = gf_edf_shoup(h1, n, p, K) \ + gf_edf_shoup(h2, n, p, K) \ + gf_edf_shoup(h3, n, p, K) return _sort_factors(factors, multiple=False) def gf_zassenhaus(f, p, K): """ Factor a square-free ``f`` in ``GF(p)[x]`` for medium ``p``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_zassenhaus >>> gf_zassenhaus(ZZ.map([1, 4, 3]), 5, ZZ) [[1, 1], [1, 3]] """ factors = [] for factor, n in gf_ddf_zassenhaus(f, p, K): factors += gf_edf_zassenhaus(factor, n, p, K) return _sort_factors(factors, multiple=False) def gf_shoup(f, p, K): """ Factor a square-free ``f`` in ``GF(p)[x]`` for large ``p``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_shoup >>> gf_shoup(ZZ.map([1, 4, 3]), 5, ZZ) [[1, 1], [1, 3]] """ factors = [] for factor, n in gf_ddf_shoup(f, p, K): factors += gf_edf_shoup(factor, n, p, K) return _sort_factors(factors, multiple=False) _factor_methods = { 'berlekamp': gf_berlekamp, # ``p`` : small 'zassenhaus': gf_zassenhaus, # ``p`` : medium 'shoup': gf_shoup, # ``p`` : large } def gf_factor_sqf(f, p, K, method=None): """ Factor a square-free polynomial ``f`` in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_factor_sqf >>> gf_factor_sqf(ZZ.map([3, 2, 4]), 5, ZZ) (3, [[1, 1], [1, 3]]) """ lc, f = gf_monic(f, p, K) if gf_degree(f) < 1: return lc, [] method = method or query('GF_FACTOR_METHOD') if method is not None: factors = _factor_methods[method](f, p, K) else: factors = gf_zassenhaus(f, p, K) return lc, factors def gf_factor(f, p, K): """ Factor (non square-free) polynomials in ``GF(p)[x]``. Given a possibly non square-free polynomial ``f`` in ``GF(p)[x]``, returns its complete factorization into irreducibles:: f_1(x)e_1 f_2(x)e_2 ... f_d(x)*e_d where each ``f_i`` is a monic polynomial and ``gcd(f_i, f_j) == 1``, for ``i != j``. The result is given as a tuple consisting of the leading coefficient of ``f`` and a list of factors of ``f`` with their multiplicities. The algorithm proceeds by first computing square-free decomposition of ``f`` and then iteratively factoring each of square-free factors. Consider a non square-free polynomial ``f = (7x + 1) (x + 2)2`` in ``GF(11)[x]``. We obtain its factorization into irreducibles as follows:: >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_factor >>> gf_factor(ZZ.map([5, 2, 7, 2]), 11, ZZ) (5, [([1, 2], 1), ([1, 8], 2)]) We arrived with factorization ``f = 5 (x + 2) (x + 8)2``. We didn't recover the exact form of the input polynomial because we requested to get monic factors of ``f`` and its leading coefficient separately. Square-free factors of ``f`` can be factored into irreducibles over ``GF(p)`` using three very different methods: Berlekamp efficient for very small values of ``p`` (usually ``p < 25``) Cantor-Zassenhaus efficient on average input and with "typical" ``p`` Shoup-Kaltofen-Gathen efficient with very large inputs and modulus If you want to use a specific factorization method, instead of the default one, set ``GF_FACTOR_METHOD`` with one of ``berlekamp``, ``zassenhaus`` or ``shoup`` values. References ========== .. [1] [Gathen99]_ """ lc, f = gf_monic(f, p, K) if gf_degree(f) < 1: return lc, [] factors = [] for g, n in gf_sqf_list(f, p, K)[1]: for h in gf_factor_sqf(g, p, K)[1]: factors.append((h, n)) return lc, _sort_factors(factors) def gf_value(f, a): """ Value of polynomial 'f' at 'a' in field R. Examples ======== >>> from sympy.polys.galoistools import gf_value >>> gf_value([1, 7, 2, 4], 11) 2204 """ result = 0 for c in f: result = a result += c return result def linear_congruence(a, b, m): """ Returns the values of x satisfying ax congruent b mod(m) Here m is positive integer and a, b are natural numbers. This function returns only those values of x which are distinct mod(m). Examples ======== >>> from sympy.polys.galoistools import linear_congruence >>> linear_congruence(3, 12, 15) [4, 9, 14] There are 3 solutions distinct mod(15) since gcd(a, m) = gcd(3, 15) = 3. References ========== .. [1] https://en.wikipedia.org/wiki/Linear_congruence_theorem """ from sympy.polys.polytools import gcdex if a % m == 0: if b % m == 0: return list(range(m)) else: return [] r, _, g = gcdex(a, m) if b % g != 0: return [] return [(r * b // g + t * m // g) % m for t in range(g)] def _raise_mod_power(x, s, p, f): """ Used in gf_csolve to generate solutions of f(x) cong 0 mod(p(s + 1)) from the solutions of f(x) cong 0 mod(ps). Examples ======== >>> from sympy.polys.galoistools import _raise_mod_power >>> from sympy.polys.galoistools import csolve_prime These is the solutions of f(x) = x2 + x + 7 cong 0 mod(3) >>> f = [1, 1, 7] >>> csolve_prime(f, 3) [1] >>> [ i for i in range(3) if not (i2 + i + 7) % 3] [1] The solutions of f(x) cong 0 mod(9) are constructed from the values returned from _raise_mod_power: >>> x, s, p = 1, 1, 3 >>> V = _raise_mod_power(x, s, p, f) >>> [x + v * ps for v in V] [1, 4, 7] And these are confirmed with the following: >>> [ i for i in range(32) if not (i2 + i + 7) % 32] [1, 4, 7] """ from sympy.polys.domains import ZZ f_f = gf_diff(f, p, ZZ) alpha = gf_value(f_f, x) beta = - gf_value(f, x) // ps return linear_congruence(alpha, beta, p) def csolve_prime(f, p, e=1): """ Solutions of f(x) congruent 0 mod(pe). Examples ======== >>> from sympy.polys.galoistools import csolve_prime >>> csolve_prime([1, 1, 7], 3, 1) [1] >>> csolve_prime([1, 1, 7], 3, 2) [1, 4, 7] Solutions [7, 4, 1] (mod 3*2) are generated by ``_raise_mod_power()`` from solution [1] (mod 3). """ from sympy.polys.domains import ZZ X1 = [i for i in range(p) if gf_eval(f, i, p, ZZ) == 0] if e == 1: return X1 X = [] S = list(zip(X1, [1]len(X1))) while S: x, s = S.pop() if s == e: X.append(x) else: s1 = s + 1 ps = p*s S.extend([(x + vps, s1) for v in _raise_mod_power(x, s, p, f)]) return sorted(X) def gf_csolve(f, n): """ To solve f(x) congruent 0 mod(n). n is divided into canonical factors and f(x) cong 0 mod(p**e) will be solved for each factor. Applying the Chinese Remainder Theorem to the results returns the final answers. Examples ======== Solve [1, 1, 7] congruent 0 mod(189): >>> from sympy.polys.galoistools import gf_csolve >>> gf_csolve([1, 1, 7], 189) [13, 49, 76, 112, 139, 175] References ========== .. [1] 'An introduction to the Theory of Numbers' 5th Edition by Ivan Niven, Zuckerman and Montgomery. """ from sympy.polys.domains import ZZ P = factorint(n) X = [csolve_prime(f, p, e) for p, e in P.items()] pools = list(map(tuple, X)) perms = [[]] for pool in pools: perms = [x + [y] for x in perms for y in pool] dist_factors = [pow(p, e) for p, e in P.items()] return sorted([gf_crt(per, dist_factors, ZZ) for per in perms])
8f2f64c1f1820f06619c366df5c55d93e54c8ec94587d20f521c7c217f85871a	# -- coding: utf-8 -- """ This module contains functions for the computation of Euclidean, (generalized) Sturmian, (modified) subresultant polynomial remainder sequences (prs's) of two polynomials; included are also three functions for the computation of the resultant of two polynomials. Except for the function res_z(), which computes the resultant of two polynomials, the pseudo-remainder function prem() of sympy is _not_ used by any of the functions in the module. Instead of prem() we use the function rem_z(). Included is also the function quo_z(). An explanation of why we avoid prem() can be found in the references stated in the docstring of rem_z(). 1. Theoretical background: ========================== Consider the polynomials f, g ∈ Z[x] of degrees deg(f) = n and deg(g) = m with n ≥ m. Definition 1: ============= The sign sequence of a polynomial remainder sequence (prs) is the sequence of signs of the leading coefficients of its polynomials. Sign sequences can be computed with the function: sign_seq(poly_seq, x) Definition 2: ============= A polynomial remainder sequence (prs) is called complete if the degree difference between any two consecutive polynomials is 1; otherwise, it called incomplete. It is understood that f, g belong to the sequences mentioned in the two definitions above. 1A. Euclidean and subresultant prs's: ===================================== The subresultant prs of f, g is a sequence of polynomials in Z[x] analogous to the Euclidean prs, the sequence obtained by applying on f, g Euclid’s algorithm for polynomial greatest common divisors (gcd) in Q[x]. The subresultant prs differs from the Euclidean prs in that the coefficients of each polynomial in the former sequence are determinants --- also referred to as subresultants --- of appropriately selected sub-matrices of sylvester1(f, g, x), Sylvester’s matrix of 1840 of dimensions (n + m) × (n + m). Recall that the determinant of sylvester1(f, g, x) itself is called the resultant of f, g and serves as a criterion of whether the two polynomials have common roots or not. In sympy the resultant is computed with the function resultant(f, g, x). This function does _not_ evaluate the determinant of sylvester(f, g, x, 1); instead, it returns the last member of the subresultant prs of f, g, multiplied (if needed) by an appropriate power of -1; see the caveat below. In this module we use three functions to compute the resultant of f, g: a) res(f, g, x) computes the resultant by evaluating the determinant of sylvester(f, g, x, 1); b) res_q(f, g, x) computes the resultant recursively, by performing polynomial divisions in Q[x] with the function rem(); c) res_z(f, g, x) computes the resultant recursively, by performing polynomial divisions in Z[x] with the function prem(). Caveat: If Df = degree(f, x) and Dg = degree(g, x), then: resultant(f, g, x) = (-1)*(DfDg) * resultant(g, f, x). For complete prs’s the sign sequence of the Euclidean prs of f, g is identical to the sign sequence of the subresultant prs of f, g and the coefficients of one sequence are easily computed from the coefficients of the other. For incomplete prs’s the polynomials in the subresultant prs, generally differ in sign from those of the Euclidean prs, and --- unlike the case of complete prs’s --- it is not at all obvious how to compute the coefficients of one sequence from the coefficients of the other. 1B. Sturmian and modified subresultant prs's: ============================================= For the same polynomials f, g ∈ Z[x] mentioned above, their ``modified'' subresultant prs is a sequence of polynomials similar to the Sturmian prs, the sequence obtained by applying in Q[x] Sturm’s algorithm on f, g. The two sequences differ in that the coefficients of each polynomial in the modified subresultant prs are the determinants --- also referred to as modified subresultants --- of appropriately selected sub-matrices of sylvester2(f, g, x), Sylvester’s matrix of 1853 of dimensions 2n × 2n. The determinant of sylvester2 itself is called the modified resultant of f, g and it also can serve as a criterion of whether the two polynomials have common roots or not. For complete prs’s the sign sequence of the Sturmian prs of f, g is identical to the sign sequence of the modified subresultant prs of f, g and the coefficients of one sequence are easily computed from the coefficients of the other. For incomplete prs’s the polynomials in the modified subresultant prs, generally differ in sign from those of the Sturmian prs, and --- unlike the case of complete prs’s --- it is not at all obvious how to compute the coefficients of one sequence from the coefficients of the other. As Sylvester pointed out, the coefficients of the polynomial remainders obtained as (modified) subresultants are the smallest possible without introducing rationals and without computing (integer) greatest common divisors. 1C. On terminology: =================== Whence the terminology? Well generalized Sturmian prs's are ``modifications'' of Euclidean prs's; the hint came from the title of the Pell-Gordon paper of 1917. In the literature one also encounters the name ``non signed'' and ``signed'' prs for Euclidean and Sturmian prs respectively. Likewise ``non signed'' and ``signed'' subresultant prs for subresultant and modified subresultant prs respectively. 2. Functions in the module: =========================== No function utilizes sympy's function prem(). 2A. Matrices: ============= The functions sylvester(f, g, x, method=1) and sylvester(f, g, x, method=2) compute either Sylvester matrix. They can be used to compute (modified) subresultant prs's by direct determinant evaluation. The function bezout(f, g, x, method='prs') provides a matrix of smaller dimensions than either Sylvester matrix. It is the function of choice for computing (modified) subresultant prs's by direct determinant evaluation. sylvester(f, g, x, method=1) sylvester(f, g, x, method=2) bezout(f, g, x, method='prs') The following identity holds: bezout(f, g, x, method='prs') = backward_eye(deg(f))bezout(f, g, x, method='bz')backward_eye(deg(f)) 2B. Subresultant and modified subresultant prs's by =================================================== determinant evaluations: ======================= We use the Sylvester matrices of 1840 and 1853 to compute, respectively, subresultant and modified subresultant polynomial remainder sequences. However, for large matrices this approach takes a lot of time. Instead of utilizing the Sylvester matrices, we can employ the Bezout matrix which is of smaller dimensions. subresultants_sylv(f, g, x) modified_subresultants_sylv(f, g, x) subresultants_bezout(f, g, x) modified_subresultants_bezout(f, g, x) 2C. Subresultant prs's by ONE determinant evaluation: ===================================================== All three functions in this section evaluate one determinant per remainder polynomial; this is the determinant of an appropriately selected sub-matrix of sylvester1(f, g, x), Sylvester’s matrix of 1840. To compute the remainder polynomials the function subresultants_rem(f, g, x) employs rem(f, g, x). By contrast, the other two functions implement Van Vleck’s ideas of 1900 and compute the remainder polynomials by trinagularizing sylvester2(f, g, x), Sylvester’s matrix of 1853. subresultants_rem(f, g, x) subresultants_vv(f, g, x) subresultants_vv_2(f, g, x). 2E. Euclidean, Sturmian prs's in Q[x]: ====================================== euclid_q(f, g, x) sturm_q(f, g, x) 2F. Euclidean, Sturmian and (modified) subresultant prs's P-G: ============================================================== All functions in this section are based on the Pell-Gordon (P-G) theorem of 1917. Computations are done in Q[x], employing the function rem(f, g, x) for the computation of the remainder polynomials. euclid_pg(f, g, x) sturm pg(f, g, x) subresultants_pg(f, g, x) modified_subresultants_pg(f, g, x) 2G. Euclidean, Sturmian and (modified) subresultant prs's A-M-V: ================================================================ All functions in this section are based on the Akritas-Malaschonok- Vigklas (A-M-V) theorem of 2015. Computations are done in Z[x], employing the function rem_z(f, g, x) for the computation of the remainder polynomials. euclid_amv(f, g, x) sturm_amv(f, g, x) subresultants_amv(f, g, x) modified_subresultants_amv(f, g, x) 2Ga. Exception: =============== subresultants_amv_q(f, g, x) This function employs rem(f, g, x) for the computation of the remainder polynomials, despite the fact that it implements the A-M-V Theorem. It is included in our module in order to show that theorems P-G and A-M-V can be implemented utilizing either the function rem(f, g, x) or the function rem_z(f, g, x). For clearly historical reasons --- since the Collins-Brown-Traub coefficients-reduction factor β_i was not available in 1917 --- we have implemented the Pell-Gordon theorem with the function rem(f, g, x) and the A-M-V Theorem with the function rem_z(f, g, x). 2H. Resultants: =============== res(f, g, x) res_q(f, g, x) res_z(f, g, x) """ from __future__ import print_function, division from sympy import (Abs, degree, expand, eye, floor, LC, Matrix, nan, Poly, pprint) from sympy import (QQ, pquo, quo, prem, rem, S, sign, simplify, summation, var, zeros) from sympy.polys.polyerrors import PolynomialError def sylvester(f, g, x, method = 1): ''' The input polynomials f, g are in Z[x] or in Q[x]. Let m = degree(f, x), n = degree(g, x) and mx = max( m , n ). a. If method = 1 (default), computes sylvester1, Sylvester's matrix of 1840 of dimension (m + n) x (m + n). The determinants of properly chosen submatrices of this matrix (a.k.a. subresultants) can be used to compute the coefficients of the Euclidean PRS of f, g. b. If method = 2, computes sylvester2, Sylvester's matrix of 1853 of dimension (2mx) x (2mx). The determinants of properly chosen submatrices of this matrix (a.k.a. ``modified'' subresultants) can be used to compute the coefficients of the Sturmian PRS of f, g. Applications of these Matrices can be found in the references below. Especially, for applications of sylvester2, see the first reference!! References ========== 1. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``On a Theorem by Van Vleck Regarding Sturm Sequences. Serdica Journal of Computing, Vol. 7, No 4, 101–134, 2013. 2. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``Sturm Sequences and Modified Subresultant Polynomial Remainder Sequences.'' Serdica Journal of Computing, Vol. 8, No 1, 29–46, 2014. ''' # obtain degrees of polys m, n = degree( Poly(f, x), x), degree( Poly(g, x), x) # Special cases: # A:: case m = n < 0 (i.e. both polys are 0) if m == n and n < 0: return Matrix([]) # B:: case m = n = 0 (i.e. both polys are constants) if m == n and n == 0: return Matrix([]) # C:: m == 0 and n < 0 or m < 0 and n == 0 # (i.e. one poly is constant and the other is 0) if m == 0 and n < 0: return Matrix([]) elif m < 0 and n == 0: return Matrix([]) # D:: m >= 1 and n < 0 or m < 0 and n >=1 # (i.e. one poly is of degree >=1 and the other is 0) if m >= 1 and n < 0: return Matrix([0]) elif m < 0 and n >= 1: return Matrix([0]) fp = Poly(f, x).all_coeffs() gp = Poly(g, x).all_coeffs() # Sylvester's matrix of 1840 (default; a.k.a. sylvester1) if method <= 1: M = zeros(m + n) k = 0 for i in range(n): j = k for coeff in fp: M[i, j] = coeff j = j + 1 k = k + 1 k = 0 for i in range(n, m + n): j = k for coeff in gp: M[i, j] = coeff j = j + 1 k = k + 1 return M # Sylvester's matrix of 1853 (a.k.a sylvester2) if method >= 2: if len(fp) < len(gp): h = [] for i in range(len(gp) - len(fp)): h.append(0) fp[ : 0] = h else: h = [] for i in range(len(fp) - len(gp)): h.append(0) gp[ : 0] = h mx = max(m, n) dim = 2mx M = zeros( dim ) k = 0 for i in range( mx ): j = k for coeff in fp: M[2i, j] = coeff j = j + 1 j = k for coeff in gp: M[2i + 1, j] = coeff j = j + 1 k = k + 1 return M def process_matrix_output(poly_seq, x): """ poly_seq is a polynomial remainder sequence computed either by (modified_)subresultants_bezout or by (modified_)subresultants_sylv. This function removes from poly_seq all zero polynomials as well as all those whose degree is equal to the degree of a preceding polynomial in poly_seq, as we scan it from left to right. """ L = poly_seq[:] # get a copy of the input sequence d = degree(L[1], x) i = 2 while i < len(L): d_i = degree(L[i], x) if d_i < 0: # zero poly L.remove(L[i]) i = i - 1 if d == d_i: # poly degree equals degree of previous poly L.remove(L[i]) i = i - 1 if d_i >= 0: d = d_i i = i + 1 return L def subresultants_sylv(f, g, x): """ The input polynomials f, g are in Z[x] or in Q[x]. It is assumed that deg(f) >= deg(g). Computes the subresultant polynomial remainder sequence (prs) of f, g by evaluating determinants of appropriately selected submatrices of sylvester(f, g, x, 1). The dimensions of the latter are (deg(f) + deg(g)) x (deg(f) + deg(g)). Each coefficient is computed by evaluating the determinant of the corresponding submatrix of sylvester(f, g, x, 1). If the subresultant prs is complete, then the output coincides with the Euclidean sequence of the polynomials f, g. References: =========== 1. G.M.Diaz-Toca,L.Gonzalez-Vega: Various New Expressions for Subresultants and Their Applications. Appl. Algebra in Engin., Communic. and Comp., Vol. 15, 233–266, 2004. """ # make sure neither f nor g is 0 if f == 0 or g == 0: return [f, g] n = degF = degree(f, x) m = degG = degree(g, x) # make sure proper degrees if n == 0 and m == 0: return [f, g] if n < m: n, m, degF, degG, f, g = m, n, degG, degF, g, f if n > 0 and m == 0: return [f, g] SR_L = [f, g] # subresultant list # form matrix sylvester(f, g, x, 1) S = sylvester(f, g, x, 1) # pick appropriate submatrices of S # and form subresultant polys j = m - 1 while j > 0: Sp = S[:, :] # copy of S # delete last j rows of coeffs of g for ind in range(m + n - j, m + n): Sp.row_del(m + n - j) # delete last j rows of coeffs of f for ind in range(m - j, m): Sp.row_del(m - j) # evaluate determinants and form coefficients list coeff_L, k, l = [], Sp.rows, 0 while l <= j: coeff_L.append(Sp[ : , 0 : k].det()) Sp.col_swap(k - 1, k + l) l += 1 # form poly and append to SP_L SR_L.append(Poly(coeff_L, x).as_expr()) j -= 1 # j = 0 SR_L.append(S.det()) return process_matrix_output(SR_L, x) def modified_subresultants_sylv(f, g, x): """ The input polynomials f, g are in Z[x] or in Q[x]. It is assumed that deg(f) >= deg(g). Computes the modified subresultant polynomial remainder sequence (prs) of f, g by evaluating determinants of appropriately selected submatrices of sylvester(f, g, x, 2). The dimensions of the latter are (2deg(f)) x (2deg(f)). Each coefficient is computed by evaluating the determinant of the corresponding submatrix of sylvester(f, g, x, 2). If the modified subresultant prs is complete, then the output coincides with the Sturmian sequence of the polynomials f, g. References: =========== 1. A. G. Akritas,G.I. Malaschonok and P.S. Vigklas: Sturm Sequences and Modified Subresultant Polynomial Remainder Sequences. Serdica Journal of Computing, Vol. 8, No 1, 29--46, 2014. """ # make sure neither f nor g is 0 if f == 0 or g == 0: return [f, g] n = degF = degree(f, x) m = degG = degree(g, x) # make sure proper degrees if n == 0 and m == 0: return [f, g] if n < m: n, m, degF, degG, f, g = m, n, degG, degF, g, f if n > 0 and m == 0: return [f, g] SR_L = [f, g] # modified subresultant list # form matrix sylvester(f, g, x, 2) S = sylvester(f, g, x, 2) # pick appropriate submatrices of S # and form modified subresultant polys j = m - 1 while j > 0: # delete last 2j rows of pairs of coeffs of f, g Sp = S[0:2n - 2j, :] # copy of first 2n - 2j rows of S # evaluate determinants and form coefficients list coeff_L, k, l = [], Sp.rows, 0 while l <= j: coeff_L.append(Sp[ : , 0 : k].det()) Sp.col_swap(k - 1, k + l) l += 1 # form poly and append to SP_L SR_L.append(Poly(coeff_L, x).as_expr()) j -= 1 # j = 0 SR_L.append(S.det()) return process_matrix_output(SR_L, x) def res(f, g, x): """ The input polynomials f, g are in Z[x] or in Q[x]. The output is the resultant of f, g computed by evaluating the determinant of the matrix sylvester(f, g, x, 1). References: =========== 1. J. S. Cohen: Computer Algebra and Symbolic Computation - Mathematical Methods. A. K. Peters, 2003. """ if f == 0 or g == 0: raise PolynomialError("The resultant of %s and %s is not defined" % (f, g)) else: return sylvester(f, g, x, 1).det() def res_q(f, g, x): """ The input polynomials f, g are in Z[x] or in Q[x]. The output is the resultant of f, g computed recursively by polynomial divisions in Q[x], using the function rem. See Cohen's book p. 281. References: =========== 1. J. S. Cohen: Computer Algebra and Symbolic Computation - Mathematical Methods. A. K. Peters, 2003. """ m = degree(f, x) n = degree(g, x) if m < n: return (-1)*(mn) * res_q(g, f, x) elif n == 0: # g is a constant return gm else: r = rem(f, g, x) if r == 0: return 0 else: s = degree(r, x) l = LC(g, x) return (-1)(mn) l*(m-s)res_q(g, r, x) def res_z(f, g, x): """ The input polynomials f, g are in Z[x] or in Q[x]. The output is the resultant of f, g computed recursively by polynomial divisions in Z[x], using the function prem(). See Cohen's book p. 283. References: =========== 1. J. S. Cohen: Computer Algebra and Symbolic Computation - Mathematical Methods. A. K. Peters, 2003. """ m = degree(f, x) n = degree(g, x) if m < n: return (-1)*(mn) * res_z(g, f, x) elif n == 0: # g is a constant return gm else: r = prem(f, g, x) if r == 0: return 0 else: delta = m - n + 1 w = (-1)(mn) res_z(g, r, x) s = degree(r, x) l = LC(g, x) k = delta * n - m + s return quo(w, l*k, x) def sign_seq(poly_seq, x): """ Given a sequence of polynomials poly_seq, it returns the sequence of signs of the leading coefficients of the polynomials in poly_seq. """ return [sign(LC(poly_seq[i], x)) for i in range(len(poly_seq))] def bezout(p, q, x, method='bz'): """ The input polynomials p, q are in Z[x] or in Q[x]. Let mx = max( degree(p, x) , degree(q, x) ). The default option bezout(p, q, x, method='bz') returns Bezout's symmetric matrix of p and q, of dimensions (mx) x (mx). The determinant of this matrix is equal to the determinant of sylvester2, Sylvester's matrix of 1853, whose dimensions are (2mx) x (2mx); however the subresultants of these two matrices may differ. The other option, bezout(p, q, x, 'prs'), is of interest to us in this module because it returns a matrix equivalent to sylvester2. In this case all subresultants of the two matrices are identical. Both the subresultant polynomial remainder sequence (prs) and the modified subresultant prs of p and q can be computed by evaluating determinants of appropriately selected submatrices of bezout(p, q, x, 'prs') --- one determinant per coefficient of the remainder polynomials. The matrices bezout(p, q, x, 'bz') and bezout(p, q, x, 'prs') are related by the formula bezout(p, q, x, 'prs') = backward_eye(deg(p)) bezout(p, q, x, 'bz') * backward_eye(deg(p)), where backward_eye() is the backward identity function. References ========== 1. G.M.Diaz-Toca,L.Gonzalez-Vega: Various New Expressions for Subresultants and Their Applications. Appl. Algebra in Engin., Communic. and Comp., Vol. 15, 233–266, 2004. """ # obtain degrees of polys m, n = degree( Poly(p, x), x), degree( Poly(q, x), x) # Special cases: # A:: case m = n < 0 (i.e. both polys are 0) if m == n and n < 0: return Matrix([]) # B:: case m = n = 0 (i.e. both polys are constants) if m == n and n == 0: return Matrix([]) # C:: m == 0 and n < 0 or m < 0 and n == 0 # (i.e. one poly is constant and the other is 0) if m == 0 and n < 0: return Matrix([]) elif m < 0 and n == 0: return Matrix([]) # D:: m >= 1 and n < 0 or m < 0 and n >=1 # (i.e. one poly is of degree >=1 and the other is 0) if m >= 1 and n < 0: return Matrix([0]) elif m < 0 and n >= 1: return Matrix([0]) y = var('y') # expr is 0 when x = y expr = p * q.subs({x:y}) - p.subs({x:y}) * q # hence expr is exactly divisible by x - y poly = Poly( quo(expr, x-y), x, y) # form Bezout matrix and store them in B as indicated to get # the LC coefficient of each poly either in the first position # of each row (method='prs') or in the last (method='bz'). mx = max(m, n) B = zeros(mx) for i in range(mx): for j in range(mx): if method == 'prs': B[mx - 1 - i, mx - 1 - j] = poly.nth(i, j) else: B[i, j] = poly.nth(i, j) return B def backward_eye(n): ''' Returns the backward identity matrix of dimensions n x n. Needed to "turn" the Bezout matrices so that the leading coefficients are first. See docstring of the function bezout(p, q, x, method='bz'). ''' M = eye(n) # identity matrix of order n for i in range(int(M.rows / 2)): M.row_swap(0 + i, M.rows - 1 - i) return M def subresultants_bezout(p, q, x): """ The input polynomials p, q are in Z[x] or in Q[x]. It is assumed that degree(p, x) >= degree(q, x). Computes the subresultant polynomial remainder sequence of p, q by evaluating determinants of appropriately selected submatrices of bezout(p, q, x, 'prs'). The dimensions of the latter are deg(p) x deg(p). Each coefficient is computed by evaluating the determinant of the corresponding submatrix of bezout(p, q, x, 'prs'). bezout(p, q, x, 'prs) is used instead of sylvester(p, q, x, 1), Sylvester's matrix of 1840, because the dimensions of the latter are (deg(p) + deg(q)) x (deg(p) + deg(q)). If the subresultant prs is complete, then the output coincides with the Euclidean sequence of the polynomials p, q. References ========== 1. G.M.Diaz-Toca,L.Gonzalez-Vega: Various New Expressions for Subresultants and Their Applications. Appl. Algebra in Engin., Communic. and Comp., Vol. 15, 233–266, 2004. """ # make sure neither p nor q is 0 if p == 0 or q == 0: return [p, q] f, g = p, q n = degF = degree(f, x) m = degG = degree(g, x) # make sure proper degrees if n == 0 and m == 0: return [f, g] if n < m: n, m, degF, degG, f, g = m, n, degG, degF, g, f if n > 0 and m == 0: return [f, g] SR_L = [f, g] # subresultant list F = LC(f, x)(degF - degG) # form the bezout matrix B = bezout(f, g, x, 'prs') # pick appropriate submatrices of B # and form subresultant polys if degF > degG: j = 2 if degF == degG: j = 1 while j <= degF: M = B[0:j, :] k, coeff_L = j - 1, [] while k <= degF - 1: coeff_L.append(M[: ,0 : j].det()) if k < degF - 1: M.col_swap(j - 1, k + 1) k = k + 1 # apply Theorem 2.1 in the paper by Toca & Vega 2004 # to get correct signs SR_L.append((int((-1)(j(j-1)/2)) Poly(coeff_L, x) / F).as_expr()) j = j + 1 return process_matrix_output(SR_L, x) def modified_subresultants_bezout(p, q, x): """ The input polynomials p, q are in Z[x] or in Q[x]. It is assumed that degree(p, x) >= degree(q, x). Computes the modified subresultant polynomial remainder sequence of p, q by evaluating determinants of appropriately selected submatrices of bezout(p, q, x, 'prs'). The dimensions of the latter are deg(p) x deg(p). Each coefficient is computed by evaluating the determinant of the corresponding submatrix of bezout(p, q, x, 'prs'). bezout(p, q, x, 'prs') is used instead of sylvester(p, q, x, 2), Sylvester's matrix of 1853, because the dimensions of the latter are 2deg(p) x 2deg(p). If the modified subresultant prs is complete, and LC( p ) > 0, the output coincides with the (generalized) Sturm's sequence of the polynomials p, q. References ========== 1. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``Sturm Sequences and Modified Subresultant Polynomial Remainder Sequences.'' Serdica Journal of Computing, Vol. 8, No 1, 29–46, 2014. 2. G.M.Diaz-Toca,L.Gonzalez-Vega: Various New Expressions for Subresultants and Their Applications. Appl. Algebra in Engin., Communic. and Comp., Vol. 15, 233–266, 2004. """ # make sure neither p nor q is 0 if p == 0 or q == 0: return [p, q] f, g = p, q n = degF = degree(f, x) m = degG = degree(g, x) # make sure proper degrees if n == 0 and m == 0: return [f, g] if n < m: n, m, degF, degG, f, g = m, n, degG, degF, g, f if n > 0 and m == 0: return [f, g] SR_L = [f, g] # subresultant list # form the bezout matrix B = bezout(f, g, x, 'prs') # pick appropriate submatrices of B # and form subresultant polys if degF > degG: j = 2 if degF == degG: j = 1 while j <= degF: M = B[0:j, :] k, coeff_L = j - 1, [] while k <= degF - 1: coeff_L.append(M[: ,0 : j].det()) if k < degF - 1: M.col_swap(j - 1, k + 1) k = k + 1 ## Theorem 2.1 in the paper by Toca & Vega 2004 is _not needed_ ## in this case since ## the bezout matrix is equivalent to sylvester2 SR_L.append(( Poly(coeff_L, x)).as_expr()) j = j + 1 return process_matrix_output(SR_L, x) def sturm_pg(p, q, x, method=0): """ p, q are polynomials in Z[x] or Q[x]. It is assumed that degree(p, x) >= degree(q, x). Computes the (generalized) Sturm sequence of p and q in Z[x] or Q[x]. If q = diff(p, x, 1) it is the usual Sturm sequence. A. If method == 0, default, the remainder coefficients of the sequence are (in absolute value) ``modified'' subresultants, which for non-monic polynomials are greater than the coefficients of the corresponding subresultants by the factor Abs(LC(p)( deg(p)- deg(q))). B. If method == 1, the remainder coefficients of the sequence are (in absolute value) subresultants, which for non-monic polynomials are smaller than the coefficients of the corresponding ``modified'' subresultants by the factor Abs(LC(p)( deg(p)- deg(q))). If the Sturm sequence is complete, method=0 and LC( p ) > 0, the coefficients of the polynomials in the sequence are ``modified'' subresultants. That is, they are determinants of appropriately selected submatrices of sylvester2, Sylvester's matrix of 1853. In this case the Sturm sequence coincides with the ``modified'' subresultant prs, of the polynomials p, q. If the Sturm sequence is incomplete and method=0 then the signs of the coefficients of the polynomials in the sequence may differ from the signs of the coefficients of the corresponding polynomials in the ``modified'' subresultant prs; however, the absolute values are the same. To compute the coefficients, no determinant evaluation takes place. Instead, polynomial divisions in Q[x] are performed, using the function rem(p, q, x); the coefficients of the remainders computed this way become (``modified'') subresultants with the help of the Pell-Gordon Theorem of 1917. See also the function euclid_pg(p, q, x). References ========== 1. Pell A. J., R. L. Gordon. The Modified Remainders Obtained in Finding the Highest Common Factor of Two Polynomials. Annals of MatheMatics, Second Series, 18 (1917), No. 4, 188–193. 2. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``Sturm Sequences and Modified Subresultant Polynomial Remainder Sequences.'' Serdica Journal of Computing, Vol. 8, No 1, 29–46, 2014. """ # make sure neither p nor q is 0 if p == 0 or q == 0: return [p, q] # make sure proper degrees d0 = degree(p, x) d1 = degree(q, x) if d0 == 0 and d1 == 0: return [p, q] if d1 > d0: d0, d1 = d1, d0 p, q = q, p if d0 > 0 and d1 == 0: return [p,q] # make sure LC(p) > 0 flag = 0 if LC(p,x) < 0: flag = 1 p = -p q = -q # initialize lcf = LC(p, x)*(d0 - d1) # lcf subr = modified subr a0, a1 = p, q # the input polys sturm_seq = [a0, a1] # the output list del0 = d0 - d1 # degree difference rho1 = LC(a1, x) # leading coeff of a1 exp_deg = d1 - 1 # expected degree of a2 a2 = - rem(a0, a1, domain=QQ) # first remainder rho2 = LC(a2,x) # leading coeff of a2 d2 = degree(a2, x) # actual degree of a2 deg_diff_new = exp_deg - d2 # expected - actual degree del1 = d1 - d2 # degree difference # mul_fac is the factor by which a2 is multiplied to # get integer coefficients mul_fac_old = rho1*(del0 + del1 - deg_diff_new) # append accordingly if method == 0: sturm_seq.append( simplify(lcf a2 * Abs(mul_fac_old))) else: sturm_seq.append( simplify( a2 * Abs(mul_fac_old))) # main loop deg_diff_old = deg_diff_new while d2 > 0: a0, a1, d0, d1 = a1, a2, d1, d2 # update polys and degrees del0 = del1 # update degree difference exp_deg = d1 - 1 # new expected degree a2 = - rem(a0, a1, domain=QQ) # new remainder rho3 = LC(a2, x) # leading coeff of a2 d2 = degree(a2, x) # actual degree of a2 deg_diff_new = exp_deg - d2 # expected - actual degree del1 = d1 - d2 # degree difference # take into consideration the power # rho1deg_diff_old that was "left out" expo_old = deg_diff_old # rho1 raised to this power expo_new = del0 + del1 - deg_diff_new # rho2 raised to this power # update variables and append mul_fac_new = rho2(expo_new) * rho1*(expo_old) mul_fac_old deg_diff_old, mul_fac_old = deg_diff_new, mul_fac_new rho1, rho2 = rho2, rho3 if method == 0: sturm_seq.append( simplify(lcf * a2 * Abs(mul_fac_old))) else: sturm_seq.append( simplify( a2 * Abs(mul_fac_old))) if flag: # change the sign of the sequence sturm_seq = [-i for i in sturm_seq] # gcd is of degree > 0 ? m = len(sturm_seq) if sturm_seq[m - 1] == nan or sturm_seq[m - 1] == 0: sturm_seq.pop(m - 1) return sturm_seq def sturm_q(p, q, x): """ p, q are polynomials in Z[x] or Q[x]. It is assumed that degree(p, x) >= degree(q, x). Computes the (generalized) Sturm sequence of p and q in Q[x]. Polynomial divisions in Q[x] are performed, using the function rem(p, q, x). The coefficients of the polynomials in the Sturm sequence can be uniquely determined from the corresponding coefficients of the polynomials found either in: (a) the ``modified'' subresultant prs, (references 1, 2) or in (b) the subresultant prs (reference 3). References ========== 1. Pell A. J., R. L. Gordon. The Modified Remainders Obtained in Finding the Highest Common Factor of Two Polynomials. Annals of MatheMatics, Second Series, 18 (1917), No. 4, 188–193. 2 Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``Sturm Sequences and Modified Subresultant Polynomial Remainder Sequences.'' Serdica Journal of Computing, Vol. 8, No 1, 29–46, 2014. 3. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``A Basic Result on the Theory of Subresultants.'' Serdica Journal of Computing 10 (2016), Νο.1, 31-48. """ # make sure neither p nor q is 0 if p == 0 or q == 0: return [p, q] # make sure proper degrees d0 = degree(p, x) d1 = degree(q, x) if d0 == 0 and d1 == 0: return [p, q] if d1 > d0: d0, d1 = d1, d0 p, q = q, p if d0 > 0 and d1 == 0: return [p,q] # make sure LC(p) > 0 flag = 0 if LC(p,x) < 0: flag = 1 p = -p q = -q # initialize a0, a1 = p, q # the input polys sturm_seq = [a0, a1] # the output list a2 = -rem(a0, a1, domain=QQ) # first remainder d2 = degree(a2, x) # degree of a2 sturm_seq.append( a2 ) # main loop while d2 > 0: a0, a1, d0, d1 = a1, a2, d1, d2 # update polys and degrees a2 = -rem(a0, a1, domain=QQ) # new remainder d2 = degree(a2, x) # actual degree of a2 sturm_seq.append( a2 ) if flag: # change the sign of the sequence sturm_seq = [-i for i in sturm_seq] # gcd is of degree > 0 ? m = len(sturm_seq) if sturm_seq[m - 1] == nan or sturm_seq[m - 1] == 0: sturm_seq.pop(m - 1) return sturm_seq def sturm_amv(p, q, x, method=0): """ p, q are polynomials in Z[x] or Q[x]. It is assumed that degree(p, x) >= degree(q, x). Computes the (generalized) Sturm sequence of p and q in Z[x] or Q[x]. If q = diff(p, x, 1) it is the usual Sturm sequence. A. If method == 0, default, the remainder coefficients of the sequence are (in absolute value) ``modified'' subresultants, which for non-monic polynomials are greater than the coefficients of the corresponding subresultants by the factor Abs(LC(p)( deg(p)- deg(q))). B. If method == 1, the remainder coefficients of the sequence are (in absolute value) subresultants, which for non-monic polynomials are smaller than the coefficients of the corresponding ``modified'' subresultants by the factor Abs( LC(p)( deg(p)- deg(q)) ). If the Sturm sequence is complete, method=0 and LC( p ) > 0, then the coefficients of the polynomials in the sequence are ``modified'' subresultants. That is, they are determinants of appropriately selected submatrices of sylvester2, Sylvester's matrix of 1853. In this case the Sturm sequence coincides with the ``modified'' subresultant prs, of the polynomials p, q. If the Sturm sequence is incomplete and method=0 then the signs of the coefficients of the polynomials in the sequence may differ from the signs of the coefficients of the corresponding polynomials in the ``modified'' subresultant prs; however, the absolute values are the same. To compute the coefficients, no determinant evaluation takes place. Instead, we first compute the euclidean sequence of p and q using euclid_amv(p, q, x) and then: (a) change the signs of the remainders in the Euclidean sequence according to the pattern "-, -, +, +, -, -, +, +,..." (see Lemma 1 in the 1st reference or Theorem 3 in the 2nd reference) and (b) if method=0, assuming deg(p) > deg(q), we multiply the remainder coefficients of the Euclidean sequence times the factor Abs( LC(p)( deg(p)- deg(q)) ) to make them modified subresultants. See also the function sturm_pg(p, q, x). References ========== 1. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``A Basic Result on the Theory of Subresultants.'' Serdica Journal of Computing 10 (2016), Νο.1, 31-48. 2. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``On the Remainders Obtained in Finding the Greatest Common Divisor of Two Polynomials.'' Serdica Journal of Computing 9(2) (2015), 123-138. 3. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``Subresultant Polynomial Remainder Sequences Obtained by Polynomial Divisions in Q[x] or in Z[x].'' Serdica Journal of Computing 10 (2016), Νο.3-4, 197-217. """ # compute the euclidean sequence prs = euclid_amv(p, q, x) # defensive if prs == [] or len(prs) == 2: return prs # the coefficients in prs are subresultants and hence are smaller # than the corresponding subresultants by the factor # Abs( LC(prs[0])( deg(prs[0]) - deg(prs[1])) ); Theorem 2, 2nd reference. lcf = Abs( LC(prs[0])*( degree(prs[0], x) - degree(prs[1], x) ) ) # the signs of the first two polys in the sequence stay the same sturm_seq = [prs[0], prs[1]] # change the signs according to "-, -, +, +, -, -, +, +,..." # and multiply times lcf if needed flag = 0 m = len(prs) i = 2 while i <= m-1: if flag == 0: sturm_seq.append( - prs[i] ) i = i + 1 if i == m: break sturm_seq.append( - prs[i] ) i = i + 1 flag = 1 elif flag == 1: sturm_seq.append( prs[i] ) i = i + 1 if i == m: break sturm_seq.append( prs[i] ) i = i + 1 flag = 0 # subresultants or modified subresultants? if method == 0 and lcf > 1: aux_seq = [sturm_seq[0], sturm_seq[1]] for i in range(2, m): aux_seq.append(simplify(sturm_seq[i] lcf )) sturm_seq = aux_seq return sturm_seq def euclid_pg(p, q, x): """ p, q are polynomials in Z[x] or Q[x]. It is assumed that degree(p, x) >= degree(q, x). Computes the Euclidean sequence of p and q in Z[x] or Q[x]. If the Euclidean sequence is complete the coefficients of the polynomials in the sequence are subresultants. That is, they are determinants of appropriately selected submatrices of sylvester1, Sylvester's matrix of 1840. In this case the Euclidean sequence coincides with the subresultant prs of the polynomials p, q. If the Euclidean sequence is incomplete the signs of the coefficients of the polynomials in the sequence may differ from the signs of the coefficients of the corresponding polynomials in the subresultant prs; however, the absolute values are the same. To compute the Euclidean sequence, no determinant evaluation takes place. We first compute the (generalized) Sturm sequence of p and q using sturm_pg(p, q, x, 1), in which case the coefficients are (in absolute value) equal to subresultants. Then we change the signs of the remainders in the Sturm sequence according to the pattern "-, -, +, +, -, -, +, +,..." ; see Lemma 1 in the 1st reference or Theorem 3 in the 2nd reference as well as the function sturm_pg(p, q, x). References ========== 1. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``A Basic Result on the Theory of Subresultants.'' Serdica Journal of Computing 10 (2016), Νο.1, 31-48. 2. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``On the Remainders Obtained in Finding the Greatest Common Divisor of Two Polynomials.'' Serdica Journal of Computing 9(2) (2015), 123-138. 3. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``Subresultant Polynomial Remainder Sequences Obtained by Polynomial Divisions in Q[x] or in Z[x].'' Serdica Journal of Computing 10 (2016), Νο.3-4, 197-217. """ # compute the sturmian sequence using the Pell-Gordon (or AMV) theorem # with the coefficients in the prs being (in absolute value) subresultants prs = sturm_pg(p, q, x, 1) ## any other method would do # defensive if prs == [] or len(prs) == 2: return prs # the signs of the first two polys in the sequence stay the same euclid_seq = [prs[0], prs[1]] # change the signs according to "-, -, +, +, -, -, +, +,..." flag = 0 m = len(prs) i = 2 while i <= m-1: if flag == 0: euclid_seq.append(- prs[i] ) i = i + 1 if i == m: break euclid_seq.append(- prs[i] ) i = i + 1 flag = 1 elif flag == 1: euclid_seq.append(prs[i] ) i = i + 1 if i == m: break euclid_seq.append(prs[i] ) i = i + 1 flag = 0 return euclid_seq def euclid_q(p, q, x): """ p, q are polynomials in Z[x] or Q[x]. It is assumed that degree(p, x) >= degree(q, x). Computes the Euclidean sequence of p and q in Q[x]. Polynomial divisions in Q[x] are performed, using the function rem(p, q, x). The coefficients of the polynomials in the Euclidean sequence can be uniquely determined from the corresponding coefficients of the polynomials found either in: (a) the ``modified'' subresultant polynomial remainder sequence, (references 1, 2) or in (b) the subresultant polynomial remainder sequence (references 3). References ========== 1. Pell A. J., R. L. Gordon. The Modified Remainders Obtained in Finding the Highest Common Factor of Two Polynomials. Annals of MatheMatics, Second Series, 18 (1917), No. 4, 188–193. 2. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``Sturm Sequences and Modified Subresultant Polynomial Remainder Sequences.'' Serdica Journal of Computing, Vol. 8, No 1, 29–46, 2014. 3. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``A Basic Result on the Theory of Subresultants.'' Serdica Journal of Computing 10 (2016), Νο.1, 31-48. """ # make sure neither p nor q is 0 if p == 0 or q == 0: return [p, q] # make sure proper degrees d0 = degree(p, x) d1 = degree(q, x) if d0 == 0 and d1 == 0: return [p, q] if d1 > d0: d0, d1 = d1, d0 p, q = q, p if d0 > 0 and d1 == 0: return [p,q] # make sure LC(p) > 0 flag = 0 if LC(p,x) < 0: flag = 1 p = -p q = -q # initialize a0, a1 = p, q # the input polys euclid_seq = [a0, a1] # the output list a2 = rem(a0, a1, domain=QQ) # first remainder d2 = degree(a2, x) # degree of a2 euclid_seq.append( a2 ) # main loop while d2 > 0: a0, a1, d0, d1 = a1, a2, d1, d2 # update polys and degrees a2 = rem(a0, a1, domain=QQ) # new remainder d2 = degree(a2, x) # actual degree of a2 euclid_seq.append( a2 ) if flag: # change the sign of the sequence euclid_seq = [-i for i in euclid_seq] # gcd is of degree > 0 ? m = len(euclid_seq) if euclid_seq[m - 1] == nan or euclid_seq[m - 1] == 0: euclid_seq.pop(m - 1) return euclid_seq def euclid_amv(f, g, x): """ f, g are polynomials in Z[x] or Q[x]. It is assumed that degree(f, x) >= degree(g, x). Computes the Euclidean sequence of p and q in Z[x] or Q[x]. If the Euclidean sequence is complete the coefficients of the polynomials in the sequence are subresultants. That is, they are determinants of appropriately selected submatrices of sylvester1, Sylvester's matrix of 1840. In this case the Euclidean sequence coincides with the subresultant prs, of the polynomials p, q. If the Euclidean sequence is incomplete the signs of the coefficients of the polynomials in the sequence may differ from the signs of the coefficients of the corresponding polynomials in the subresultant prs; however, the absolute values are the same. To compute the coefficients, no determinant evaluation takes place. Instead, polynomial divisions in Z[x] or Q[x] are performed, using the function rem_z(f, g, x); the coefficients of the remainders computed this way become subresultants with the help of the Collins-Brown-Traub formula for coefficient reduction. References ========== 1. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``A Basic Result on the Theory of Subresultants.'' Serdica Journal of Computing 10 (2016), Νο.1, 31-48. 2. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``Subresultant Polynomial remainder Sequences Obtained by Polynomial Divisions in Q[x] or in Z[x].'' Serdica Journal of Computing 10 (2016), Νο.3-4, 197-217. """ # make sure neither f nor g is 0 if f == 0 or g == 0: return [f, g] # make sure proper degrees d0 = degree(f, x) d1 = degree(g, x) if d0 == 0 and d1 == 0: return [f, g] if d1 > d0: d0, d1 = d1, d0 f, g = g, f if d0 > 0 and d1 == 0: return [f, g] # initialize a0 = f a1 = g euclid_seq = [a0, a1] deg_dif_p1, c = degree(a0, x) - degree(a1, x) + 1, -1 # compute the first polynomial of the prs i = 1 a2 = rem_z(a0, a1, x) / Abs( (-1)deg_dif_p1 ) # first remainder euclid_seq.append( a2 ) d2 = degree(a2, x) # actual degree of a2 # main loop while d2 >= 1: a0, a1, d0, d1 = a1, a2, d1, d2 # update polys and degrees i += 1 sigma0 = -LC(a0) c = (sigma0(deg_dif_p1 - 1)) / (c(deg_dif_p1 - 2)) deg_dif_p1 = degree(a0, x) - d2 + 1 a2 = rem_z(a0, a1, x) / Abs( ((c(deg_dif_p1 - 1)) * sigma0) ) euclid_seq.append( a2 ) d2 = degree(a2, x) # actual degree of a2 # gcd is of degree > 0 ? m = len(euclid_seq) if euclid_seq[m - 1] == nan or euclid_seq[m - 1] == 0: euclid_seq.pop(m - 1) return euclid_seq def modified_subresultants_pg(p, q, x): """ p, q are polynomials in Z[x] or Q[x]. It is assumed that degree(p, x) >= degree(q, x). Computes the ``modified'' subresultant prs of p and q in Z[x] or Q[x]; the coefficients of the polynomials in the sequence are ``modified'' subresultants. That is, they are determinants of appropriately selected submatrices of sylvester2, Sylvester's matrix of 1853. To compute the coefficients, no determinant evaluation takes place. Instead, polynomial divisions in Q[x] are performed, using the function rem(p, q, x); the coefficients of the remainders computed this way become ``modified'' subresultants with the help of the Pell-Gordon Theorem of 1917. If the ``modified'' subresultant prs is complete, and LC( p ) > 0, it coincides with the (generalized) Sturm sequence of the polynomials p, q. References ========== 1. Pell A. J., R. L. Gordon. The Modified Remainders Obtained in Finding the Highest Common Factor of Two Polynomials. Annals of MatheMatics, Second Series, 18 (1917), No. 4, 188–193. 2. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``Sturm Sequences and Modified Subresultant Polynomial Remainder Sequences.'' Serdica Journal of Computing, Vol. 8, No 1, 29–46, 2014. """ # make sure neither p nor q is 0 if p == 0 or q == 0: return [p, q] # make sure proper degrees d0 = degree(p,x) d1 = degree(q,x) if d0 == 0 and d1 == 0: return [p, q] if d1 > d0: d0, d1 = d1, d0 p, q = q, p if d0 > 0 and d1 == 0: return [p,q] # initialize k = var('k') # index in summation formula u_list = [] # of elements (-1)u_i subres_l = [p, q] # mod. subr. prs output list a0, a1 = p, q # the input polys del0 = d0 - d1 # degree difference degdif = del0 # save it rho_1 = LC(a0) # lead. coeff (a0) # Initialize Pell-Gordon variables rho_list_minus_1 = sign( LC(a0, x)) # sign of LC(a0) rho1 = LC(a1, x) # leading coeff of a1 rho_list = [ sign(rho1)] # of signs p_list = [del0] # of degree differences u = summation(k, (k, 1, p_list[0])) # value of u u_list.append(u) # of u values v = sum(p_list) # v value # first remainder exp_deg = d1 - 1 # expected degree of a2 a2 = - rem(a0, a1, domain=QQ) # first remainder rho2 = LC(a2, x) # leading coeff of a2 d2 = degree(a2, x) # actual degree of a2 deg_diff_new = exp_deg - d2 # expected - actual degree del1 = d1 - d2 # degree difference # mul_fac is the factor by which a2 is multiplied to # get integer coefficients mul_fac_old = rho1(del0 + del1 - deg_diff_new) # update Pell-Gordon variables p_list.append(1 + deg_diff_new) # deg_diff_new is 0 for complete seq # apply Pell-Gordon formula (7) in second reference num = 1 # numerator of fraction for k in range(len(u_list)): num = (-1)u_list[k] num = num (-1)*v # denominator depends on complete / incomplete seq if deg_diff_new == 0: # complete seq den = 1 for k in range(len(rho_list)): den = rho_list[k]*(p_list[k] + p_list[k + 1]) den = den rho_list_minus_1 else: # incomplete seq den = 1 for k in range(len(rho_list)-1): den = rho_list[k](p_list[k] + p_list[k + 1]) den = den rho_list_minus_1 expo = (p_list[len(rho_list) - 1] + p_list[len(rho_list)] - deg_diff_new) den = den * rho_list[len(rho_list) - 1]expo # the sign of the determinant depends on sg(num / den) if sign(num / den) > 0: subres_l.append( simplify(rho_1degdifa2 Abs(mul_fac_old) ) ) else: subres_l.append(- simplify(rho_1*degdifa2* Abs(mul_fac_old) ) ) # update Pell-Gordon variables k = var('k') rho_list.append( sign(rho2)) u = summation(k, (k, 1, p_list[len(p_list) - 1])) u_list.append(u) v = sum(p_list) deg_diff_old=deg_diff_new # main loop while d2 > 0: a0, a1, d0, d1 = a1, a2, d1, d2 # update polys and degrees del0 = del1 # update degree difference exp_deg = d1 - 1 # new expected degree a2 = - rem(a0, a1, domain=QQ) # new remainder rho3 = LC(a2, x) # leading coeff of a2 d2 = degree(a2, x) # actual degree of a2 deg_diff_new = exp_deg - d2 # expected - actual degree del1 = d1 - d2 # degree difference # take into consideration the power # rho1deg_diff_old that was "left out" expo_old = deg_diff_old # rho1 raised to this power expo_new = del0 + del1 - deg_diff_new # rho2 raised to this power mul_fac_new = rho2(expo_new) * rho1*(expo_old) mul_fac_old # update variables deg_diff_old, mul_fac_old = deg_diff_new, mul_fac_new rho1, rho2 = rho2, rho3 # update Pell-Gordon variables p_list.append(1 + deg_diff_new) # deg_diff_new is 0 for complete seq # apply Pell-Gordon formula (7) in second reference num = 1 # numerator for k in range(len(u_list)): num = (-1)u_list[k] num = num (-1)*v # denominator depends on complete / incomplete seq if deg_diff_new == 0: # complete seq den = 1 for k in range(len(rho_list)): den = rho_list[k]*(p_list[k] + p_list[k + 1]) den = den rho_list_minus_1 else: # incomplete seq den = 1 for k in range(len(rho_list)-1): den = rho_list[k](p_list[k] + p_list[k + 1]) den = den rho_list_minus_1 expo = (p_list[len(rho_list) - 1] + p_list[len(rho_list)] - deg_diff_new) den = den * rho_list[len(rho_list) - 1]expo # the sign of the determinant depends on sg(num / den) if sign(num / den) > 0: subres_l.append( simplify(rho_1degdifa2 Abs(mul_fac_old) ) ) else: subres_l.append(- simplify(rho_1*degdifa2* Abs(mul_fac_old) ) ) # update Pell-Gordon variables k = var('k') rho_list.append( sign(rho2)) u = summation(k, (k, 1, p_list[len(p_list) - 1])) u_list.append(u) v = sum(p_list) # gcd is of degree > 0 ? m = len(subres_l) if subres_l[m - 1] == nan or subres_l[m - 1] == 0: subres_l.pop(m - 1) # LC( p ) < 0 m = len(subres_l) # list may be shorter now due to deg(gcd ) > 0 if LC( p ) < 0: aux_seq = [subres_l[0], subres_l[1]] for i in range(2, m): aux_seq.append(simplify(subres_l[i] * (-1) )) subres_l = aux_seq return subres_l def subresultants_pg(p, q, x): """ p, q are polynomials in Z[x] or Q[x]. It is assumed that degree(p, x) >= degree(q, x). Computes the subresultant prs of p and q in Z[x] or Q[x], from the modified subresultant prs of p and q. The coefficients of the polynomials in these two sequences differ only in sign and the factor LC(p)( deg(p)- deg(q)) as stated in Theorem 2 of the reference. The coefficients of the polynomials in the output sequence are subresultants. That is, they are determinants of appropriately selected submatrices of sylvester1, Sylvester's matrix of 1840. If the subresultant prs is complete, then it coincides with the Euclidean sequence of the polynomials p, q. References ========== 1. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ‘‘On the Remainders Obtained in Finding the Greatest Common Divisor of Two Polynomials.'' Serdica Journal of Computing 9(2) (2015), 123-138. """ # compute the modified subresultant prs lst = modified_subresultants_pg(p,q,x) ## any other method would do # defensive if lst == [] or len(lst) == 2: return lst # the coefficients in lst are modified subresultants and, hence, are # greater than those of the corresponding subresultants by the factor # LC(lst[0])( deg(lst[0]) - deg(lst[1])); see Theorem 2 in reference. lcf = LC(lst[0])( degree(lst[0], x) - degree(lst[1], x) ) # Initialize the subresultant prs list subr_seq = [lst[0], lst[1]] # compute the degree sequences m_i and j_i of Theorem 2 in reference. deg_seq = [degree(Poly(poly, x), x) for poly in lst] deg = deg_seq[0] deg_seq_s = deg_seq[1:-1] m_seq = [m-1 for m in deg_seq_s] j_seq = [deg - m for m in m_seq] # compute the AMV factors of Theorem 2 in reference. fact = [(-1)( j(j-1)/S(2) ) for j in j_seq] # shortened list without the first two polys lst_s = lst[2:] # poly lst_s[k] is multiplied times fact[k], divided by lcf # and appended to the subresultant prs list m = len(fact) for k in range(m): if sign(fact[k]) == -1: subr_seq.append(-lst_s[k] / lcf) else: subr_seq.append(lst_s[k] / lcf) return subr_seq def subresultants_amv_q(p, q, x): """ p, q are polynomials in Z[x] or Q[x]. It is assumed that degree(p, x) >= degree(q, x). Computes the subresultant prs of p and q in Q[x]; the coefficients of the polynomials in the sequence are subresultants. That is, they are determinants of appropriately selected submatrices of sylvester1, Sylvester's matrix of 1840. To compute the coefficients, no determinant evaluation takes place. Instead, polynomial divisions in Q[x] are performed, using the function rem(p, q, x); the coefficients of the remainders computed this way become subresultants with the help of the Akritas-Malaschonok-Vigklas Theorem of 2015. If the subresultant prs is complete, then it coincides with the Euclidean sequence of the polynomials p, q. References ========== 1. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``A Basic Result on the Theory of Subresultants.'' Serdica Journal of Computing 10 (2016), Νο.1, 31-48. 2. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``Subresultant Polynomial remainder Sequences Obtained by Polynomial Divisions in Q[x] or in Z[x].'' Serdica Journal of Computing 10 (2016), Νο.3-4, 197-217. """ # make sure neither p nor q is 0 if p == 0 or q == 0: return [p, q] # make sure proper degrees d0 = degree(p, x) d1 = degree(q, x) if d0 == 0 and d1 == 0: return [p, q] if d1 > d0: d0, d1 = d1, d0 p, q = q, p if d0 > 0 and d1 == 0: return [p, q] # initialize i, s = 0, 0 # counters for remainders & odd elements p_odd_index_sum = 0 # contains the sum of p_1, p_3, etc subres_l = [p, q] # subresultant prs output list a0, a1 = p, q # the input polys sigma1 = LC(a1, x) # leading coeff of a1 p0 = d0 - d1 # degree difference if p0 % 2 == 1: s += 1 phi = floor( (s + 1) / 2 ) mul_fac = 1 d2 = d1 # main loop while d2 > 0: i += 1 a2 = rem(a0, a1, domain= QQ) # new remainder if i == 1: sigma2 = LC(a2, x) else: sigma3 = LC(a2, x) sigma1, sigma2 = sigma2, sigma3 d2 = degree(a2, x) p1 = d1 - d2 psi = i + phi + p_odd_index_sum # new mul_fac mul_fac = sigma1(p0 + 1) mul_fac ## compute the sign of the first fraction in formula (9) of the paper # numerator num = (-1)*psi # denominator den = sign(mul_fac) # the sign of the determinant depends on sign( num / den ) != 0 if sign(num / den) > 0: subres_l.append( simplify(expand(a2 Abs(mul_fac)))) else: subres_l.append(- simplify(expand(a2* Abs(mul_fac)))) ## bring into mul_fac the missing power of sigma if there was a degree gap if p1 - 1 > 0: mul_fac = mul_fac * sigma1(p1 - 1) # update AMV variables a0, a1, d0, d1 = a1, a2, d1, d2 p0 = p1 if p0 % 2 ==1: s += 1 phi = floor( (s + 1) / 2 ) if i%2 == 1: p_odd_index_sum += p0 # p_i has odd index # gcd is of degree > 0 ? m = len(subres_l) if subres_l[m - 1] == nan or subres_l[m - 1] == 0: subres_l.pop(m - 1) return subres_l def compute_sign(base, expo): ''' base != 0 and expo >= 0 are integers; returns the sign of baseexpo without evaluating the power itself! ''' sb = sign(base) if sb == 1: return 1 pe = expo % 2 if pe == 0: return -sb else: return sb def rem_z(p, q, x): ''' Intended mainly for p, q polynomials in Z[x] so that, on dividing p by q, the remainder will also be in Z[x]. (However, it also works fine for polynomials in Q[x].) It is assumed that degree(p, x) >= degree(q, x). It premultiplies p by the _absolute_ value of the leading coefficient of q, raised to the power deg(p) - deg(q) + 1 and then performs polynomial division in Q[x], using the function rem(p, q, x). By contrast the function prem(p, q, x) does _not_ use the absolute value of the leading coefficient of q. This results not only in ``messing up the signs'' of the Euclidean and Sturmian prs's as mentioned in the second reference, but also in violation of the main results of the first and third references --- Theorem 4 and Theorem 1 respectively. Theorems 4 and 1 establish a one-to-one correspondence between the Euclidean and the Sturmian prs of p, q, on one hand, and the subresultant prs of p, q, on the other. References ========== 1. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``On the Remainders Obtained in Finding the Greatest Common Divisor of Two Polynomials.'' Serdica Journal of Computing, 9(2) (2015), 123-138. 2. http://planetMath.org/sturmstheorem 3. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``A Basic Result on the Theory of Subresultants.'' Serdica Journal of Computing 10 (2016), Νο.1, 31-48. ''' if (p.as_poly().is_univariate and q.as_poly().is_univariate and p.as_poly().gens == q.as_poly().gens): delta = (degree(p, x) - degree(q, x) + 1) return rem(Abs(LC(q, x))*delta p, q, x) else: return prem(p, q, x) def quo_z(p, q, x): """ Intended mainly for p, q polynomials in Z[x] so that, on dividing p by q, the quotient will also be in Z[x]. (However, it also works fine for polynomials in Q[x].) It is assumed that degree(p, x) >= degree(q, x). It premultiplies p by the _absolute_ value of the leading coefficient of q, raised to the power deg(p) - deg(q) + 1 and then performs polynomial division in Q[x], using the function quo(p, q, x). By contrast the function pquo(p, q, x) does _not_ use the absolute value of the leading coefficient of q. See also function rem_z(p, q, x) for additional comments and references. """ if (p.as_poly().is_univariate and q.as_poly().is_univariate and p.as_poly().gens == q.as_poly().gens): delta = (degree(p, x) - degree(q, x) + 1) return quo(Abs(LC(q, x))*delta p, q, x) else: return pquo(p, q, x) def subresultants_amv(f, g, x): """ p, q are polynomials in Z[x] or Q[x]. It is assumed that degree(f, x) >= degree(g, x). Computes the subresultant prs of p and q in Z[x] or Q[x]; the coefficients of the polynomials in the sequence are subresultants. That is, they are determinants of appropriately selected submatrices of sylvester1, Sylvester's matrix of 1840. To compute the coefficients, no determinant evaluation takes place. Instead, polynomial divisions in Z[x] or Q[x] are performed, using the function rem_z(p, q, x); the coefficients of the remainders computed this way become subresultants with the help of the Akritas-Malaschonok-Vigklas Theorem of 2015 and the Collins-Brown- Traub formula for coefficient reduction. If the subresultant prs is complete, then it coincides with the Euclidean sequence of the polynomials p, q. References ========== 1. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``A Basic Result on the Theory of Subresultants.'' Serdica Journal of Computing 10 (2016), Νο.1, 31-48. 2. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``Subresultant Polynomial remainder Sequences Obtained by Polynomial Divisions in Q[x] or in Z[x].'' Serdica Journal of Computing 10 (2016), Νο.3-4, 197-217. """ # make sure neither f nor g is 0 if f == 0 or g == 0: return [f, g] # make sure proper degrees d0 = degree(f, x) d1 = degree(g, x) if d0 == 0 and d1 == 0: return [f, g] if d1 > d0: d0, d1 = d1, d0 f, g = g, f if d0 > 0 and d1 == 0: return [f, g] # initialize a0 = f a1 = g subres_l = [a0, a1] deg_dif_p1, c = degree(a0, x) - degree(a1, x) + 1, -1 # initialize AMV variables sigma1 = LC(a1, x) # leading coeff of a1 i, s = 0, 0 # counters for remainders & odd elements p_odd_index_sum = 0 # contains the sum of p_1, p_3, etc p0 = deg_dif_p1 - 1 if p0 % 2 == 1: s += 1 phi = floor( (s + 1) / 2 ) # compute the first polynomial of the prs i += 1 a2 = rem_z(a0, a1, x) / Abs( (-1)deg_dif_p1 ) # first remainder sigma2 = LC(a2, x) # leading coeff of a2 d2 = degree(a2, x) # actual degree of a2 p1 = d1 - d2 # degree difference # sgn_den is the factor, the denominator 1st fraction of (9), # by which a2 is multiplied to get integer coefficients sgn_den = compute_sign( sigma1, p0 + 1 ) ## compute sign of the 1st fraction in formula (9) of the paper # numerator psi = i + phi + p_odd_index_sum num = (-1)psi # denominator den = sgn_den # the sign of the determinant depends on sign(num / den) != 0 if sign(num / den) > 0: subres_l.append( a2 ) else: subres_l.append( -a2 ) # update AMV variable if p1 % 2 == 1: s += 1 # bring in the missing power of sigma if there was gap if p1 - 1 > 0: sgn_den = sgn_den * compute_sign( sigma1, p1 - 1 ) # main loop while d2 >= 1: phi = floor( (s + 1) / 2 ) if i%2 == 1: p_odd_index_sum += p1 # p_i has odd index a0, a1, d0, d1 = a1, a2, d1, d2 # update polys and degrees p0 = p1 # update degree difference i += 1 sigma0 = -LC(a0) c = (sigma0(deg_dif_p1 - 1)) / (c(deg_dif_p1 - 2)) deg_dif_p1 = degree(a0, x) - d2 + 1 a2 = rem_z(a0, a1, x) / Abs( ((c*(deg_dif_p1 - 1)) sigma0) ) sigma3 = LC(a2, x) # leading coeff of a2 d2 = degree(a2, x) # actual degree of a2 p1 = d1 - d2 # degree difference psi = i + phi + p_odd_index_sum # update variables sigma1, sigma2 = sigma2, sigma3 # new sgn_den sgn_den = compute_sign( sigma1, p0 + 1 ) * sgn_den # compute the sign of the first fraction in formula (9) of the paper # numerator num = (-1)*psi # denominator den = sgn_den # the sign of the determinant depends on sign( num / den ) != 0 if sign(num / den) > 0: subres_l.append( a2 ) else: subres_l.append( -a2 ) # update AMV variable if p1 % 2 ==1: s += 1 # bring in the missing power of sigma if there was gap if p1 - 1 > 0: sgn_den = sgn_den compute_sign( sigma1, p1 - 1 ) # gcd is of degree > 0 ? m = len(subres_l) if subres_l[m - 1] == nan or subres_l[m - 1] == 0: subres_l.pop(m - 1) return subres_l def modified_subresultants_amv(p, q, x): """ p, q are polynomials in Z[x] or Q[x]. It is assumed that degree(p, x) >= degree(q, x). Computes the modified subresultant prs of p and q in Z[x] or Q[x], from the subresultant prs of p and q. The coefficients of the polynomials in the two sequences differ only in sign and the factor LC(p)( deg(p)- deg(q)) as stated in Theorem 2 of the reference. The coefficients of the polynomials in the output sequence are modified subresultants. That is, they are determinants of appropriately selected submatrices of sylvester2, Sylvester's matrix of 1853. If the modified subresultant prs is complete, and LC( p ) > 0, it coincides with the (generalized) Sturm's sequence of the polynomials p, q. References ========== 1. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ‘‘On the Remainders Obtained in Finding the Greatest Common Divisor of Two Polynomials.'' Serdica Journal of Computing, Serdica Journal of Computing, 9(2) (2015), 123-138. """ # compute the subresultant prs lst = subresultants_amv(p,q,x) ## any other method would do # defensive if lst == [] or len(lst) == 2: return lst # the coefficients in lst are subresultants and, hence, smaller than those # of the corresponding modified subresultants by the factor # LC(lst[0])( deg(lst[0]) - deg(lst[1])); see Theorem 2. lcf = LC(lst[0])( degree(lst[0], x) - degree(lst[1], x) ) # Initialize the modified subresultant prs list subr_seq = [lst[0], lst[1]] # compute the degree sequences m_i and j_i of Theorem 2 deg_seq = [degree(Poly(poly, x), x) for poly in lst] deg = deg_seq[0] deg_seq_s = deg_seq[1:-1] m_seq = [m-1 for m in deg_seq_s] j_seq = [deg - m for m in m_seq] # compute the AMV factors of Theorem 2 fact = [(-1)( j(j-1)/S(2) ) for j in j_seq] # shortened list without the first two polys lst_s = lst[2:] # poly lst_s[k] is multiplied times fact[k] and times lcf # and appended to the subresultant prs list m = len(fact) for k in range(m): if sign(fact[k]) == -1: subr_seq.append( simplify(-lst_s[k] lcf) ) else: subr_seq.append( simplify(lst_s[k] * lcf) ) return subr_seq def correct_sign(deg_f, deg_g, s1, rdel, cdel): """ Used in various subresultant prs algorithms. Evaluates the determinant, (a.k.a. subresultant) of a properly selected submatrix of s1, Sylvester's matrix of 1840, to get the correct sign and value of the leading coefficient of a given polynomial remainder. deg_f, deg_g are the degrees of the original polynomials p, q for which the matrix s1 = sylvester(p, q, x, 1) was constructed. rdel denotes the expected degree of the remainder; it is the number of rows to be deleted from each group of rows in s1 as described in the reference below. cdel denotes the expected degree minus the actual degree of the remainder; it is the number of columns to be deleted --- starting with the last column forming the square matrix --- from the matrix resulting after the row deletions. References ========== Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``Sturm Sequences and Modified Subresultant Polynomial Remainder Sequences.'' Serdica Journal of Computing, Vol. 8, No 1, 29–46, 2014. """ M = s1[:, :] # copy of matrix s1 # eliminate rdel rows from the first deg_g rows for i in range(M.rows - deg_f - 1, M.rows - deg_f - rdel - 1, -1): M.row_del(i) # eliminate rdel rows from the last deg_f rows for i in range(M.rows - 1, M.rows - rdel - 1, -1): M.row_del(i) # eliminate cdel columns for i in range(cdel): M.col_del(M.rows - 1) # define submatrix Md = M[:, 0: M.rows] return Md.det() def subresultants_rem(p, q, x): """ p, q are polynomials in Z[x] or Q[x]. It is assumed that degree(p, x) >= degree(q, x). Computes the subresultant prs of p and q in Z[x] or Q[x]; the coefficients of the polynomials in the sequence are subresultants. That is, they are determinants of appropriately selected submatrices of sylvester1, Sylvester's matrix of 1840. To compute the coefficients polynomial divisions in Q[x] are performed, using the function rem(p, q, x). The coefficients of the remainders computed this way become subresultants by evaluating one subresultant per remainder --- that of the leading coefficient. This way we obtain the correct sign and value of the leading coefficient of the remainder and we easily ``force'' the rest of the coefficients to become subresultants. If the subresultant prs is complete, then it coincides with the Euclidean sequence of the polynomials p, q. References ========== 1. Akritas, A. G.:``Three New Methods for Computing Subresultant Polynomial Remainder Sequences (PRS’s).'' Serdica Journal of Computing 9(1) (2015), 1-26. """ # make sure neither p nor q is 0 if p == 0 or q == 0: return [p, q] # make sure proper degrees f, g = p, q n = deg_f = degree(f, x) m = deg_g = degree(g, x) if n == 0 and m == 0: return [f, g] if n < m: n, m, deg_f, deg_g, f, g = m, n, deg_g, deg_f, g, f if n > 0 and m == 0: return [f, g] # initialize s1 = sylvester(f, g, x, 1) sr_list = [f, g] # subresultant list # main loop while deg_g > 0: r = rem(p, q, x) d = degree(r, x) if d < 0: return sr_list # make coefficients subresultants evaluating ONE determinant exp_deg = deg_g - 1 # expected degree sign_value = correct_sign(n, m, s1, exp_deg, exp_deg - d) r = simplify((r / LC(r, x)) * sign_value) # append poly with subresultant coeffs sr_list.append(r) # update degrees and polys deg_f, deg_g = deg_g, d p, q = q, r # gcd is of degree > 0 ? m = len(sr_list) if sr_list[m - 1] == nan or sr_list[m - 1] == 0: sr_list.pop(m - 1) return sr_list def pivot(M, i, j): ''' M is a matrix, and M[i, j] specifies the pivot element. All elements below M[i, j], in the j-th column, will be zeroed, if they are not already 0, according to Dodgson-Bareiss' integer preserving transformations. References ========== 1. Akritas, A. G.: ``A new method for computing polynomial greatest common divisors and polynomial remainder sequences.'' Numerische MatheMatik 52, 119-127, 1988. 2. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``On a Theorem by Van Vleck Regarding Sturm Sequences.'' Serdica Journal of Computing, 7, No 4, 101–134, 2013. ''' ma = M[:, :] # copy of matrix M rs = ma.rows # No. of rows cs = ma.cols # No. of cols for r in range(i+1, rs): if ma[r, j] != 0: for c in range(j + 1, cs): ma[r, c] = ma[i, j] * ma[r, c] - ma[i, c] * ma[r, j] ma[r, j] = 0 return ma def rotate_r(L, k): ''' Rotates right by k. L is a row of a matrix or a list. ''' ll = list(L) if ll == []: return [] for i in range(k): el = ll.pop(len(ll) - 1) ll.insert(0, el) return ll if type(L) is list else Matrix([ll]) def rotate_l(L, k): ''' Rotates left by k. L is a row of a matrix or a list. ''' ll = list(L) if ll == []: return [] for i in range(k): el = ll.pop(0) ll.insert(len(ll) - 1, el) return ll if type(L) is list else Matrix([ll]) def row2poly(row, deg, x): ''' Converts the row of a matrix to a poly of degree deg and variable x. Some entries at the beginning and/or at the end of the row may be zero. ''' k = 0 poly = [] leng = len(row) # find the beginning of the poly ; i.e. the first # non-zero element of the row while row[k] == 0: k = k + 1 # append the next deg + 1 elements to poly for j in range( deg + 1): if k + j <= leng: poly.append(row[k + j]) return Poly(poly, x) def create_ma(deg_f, deg_g, row1, row2, col_num): ''' Creates a ``small'' matrix M to be triangularized. deg_f, deg_g are the degrees of the divident and of the divisor polynomials respectively, deg_g > deg_f. The coefficients of the divident poly are the elements in row2 and those of the divisor poly are the elements in row1. col_num defines the number of columns of the matrix M. ''' if deg_g - deg_f >= 1: print('Reverse degrees') return m = zeros(deg_f - deg_g + 2, col_num) for i in range(deg_f - deg_g + 1): m[i, :] = rotate_r(row1, i) m[deg_f - deg_g + 1, :] = row2 return m def find_degree(M, deg_f): ''' Finds the degree of the poly corresponding (after triangularization) to the _last_ row of the ``small'' matrix M, created by create_ma(). deg_f is the degree of the divident poly. If _last_ row is all 0's returns None. ''' j = deg_f for i in range(0, M.cols): if M[M.rows - 1, i] == 0: j = j - 1 else: return j if j >= 0 else 0 def final_touches(s2, r, deg_g): """ s2 is sylvester2, r is the row pointer in s2, deg_g is the degree of the poly last inserted in s2. After a gcd of degree > 0 has been found with Van Vleck's method, and was inserted into s2, if its last term is not in the last column of s2, then it is inserted as many times as needed, rotated right by one each time, until the condition is met. """ R = s2.row(r-1) # find the first non zero term for i in range(s2.cols): if R[0,i] == 0: continue else: break # missing rows until last term is in last column mr = s2.cols - (i + deg_g + 1) # insert them by replacing the existing entries in the row i = 0 while mr != 0 and r + i < s2.rows : s2[r + i, : ] = rotate_r(R, i + 1) i += 1 mr -= 1 return s2 def subresultants_vv(p, q, x, method = 0): """ p, q are polynomials in Z[x] (intended) or Q[x]. It is assumed that degree(p, x) >= degree(q, x). Computes the subresultant prs of p, q by triangularizing, in Z[x] or in Q[x], all the smaller matrices encountered in the process of triangularizing sylvester2, Sylvester's matrix of 1853; see references 1 and 2 for Van Vleck's method. With each remainder, sylvester2 gets updated and is prepared to be printed if requested. If sylvester2 has small dimensions and you want to see the final, triangularized matrix use this version with method=1; otherwise, use either this version with method=0 (default) or the faster version, subresultants_vv_2(p, q, x), where sylvester2 is used implicitly. Sylvester's matrix sylvester1 is also used to compute one subresultant per remainder; namely, that of the leading coefficient, in order to obtain the correct sign and to force the remainder coefficients to become subresultants. If the subresultant prs is complete, then it coincides with the Euclidean sequence of the polynomials p, q. If the final, triangularized matrix s2 is printed, then: (a) if deg(p) - deg(q) > 1 or deg( gcd(p, q) ) > 0, several of the last rows in s2 will remain unprocessed; (b) if deg(p) - deg(q) == 0, p will not appear in the final matrix. References ========== 1. Akritas, A. G.: ``A new method for computing polynomial greatest common divisors and polynomial remainder sequences.'' Numerische MatheMatik 52, 119-127, 1988. 2. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``On a Theorem by Van Vleck Regarding Sturm Sequences.'' Serdica Journal of Computing, 7, No 4, 101–134, 2013. 3. Akritas, A. G.:``Three New Methods for Computing Subresultant Polynomial Remainder Sequences (PRS’s).'' Serdica Journal of Computing 9(1) (2015), 1-26. """ # make sure neither p nor q is 0 if p == 0 or q == 0: return [p, q] # make sure proper degrees f, g = p, q n = deg_f = degree(f, x) m = deg_g = degree(g, x) if n == 0 and m == 0: return [f, g] if n < m: n, m, deg_f, deg_g, f, g = m, n, deg_g, deg_f, g, f if n > 0 and m == 0: return [f, g] # initialize s1 = sylvester(f, g, x, 1) s2 = sylvester(f, g, x, 2) sr_list = [f, g] col_num = 2 * n # columns in s2 # make two rows (row0, row1) of poly coefficients row0 = Poly(f, x, domain = QQ).all_coeffs() leng0 = len(row0) for i in range(col_num - leng0): row0.append(0) row0 = Matrix([row0]) row1 = Poly(g,x, domain = QQ).all_coeffs() leng1 = len(row1) for i in range(col_num - leng1): row1.append(0) row1 = Matrix([row1]) # row pointer for deg_f - deg_g == 1; may be reset below r = 2 # modify first rows of s2 matrix depending on poly degrees if deg_f - deg_g > 1: r = 1 # replacing the existing entries in the rows of s2, # insert row0 (deg_f - deg_g - 1) times, rotated each time for i in range(deg_f - deg_g - 1): s2[r + i, : ] = rotate_r(row0, i + 1) r = r + deg_f - deg_g - 1 # insert row1 (deg_f - deg_g) times, rotated each time for i in range(deg_f - deg_g): s2[r + i, : ] = rotate_r(row1, r + i) r = r + deg_f - deg_g if deg_f - deg_g == 0: r = 0 # main loop while deg_g > 0: # create a small matrix M, and triangularize it; M = create_ma(deg_f, deg_g, row1, row0, col_num) # will need only the first and last rows of M for i in range(deg_f - deg_g + 1): M1 = pivot(M, i, i) M = M1[:, :] # treat last row of M as poly; find its degree d = find_degree(M, deg_f) if d == None: break exp_deg = deg_g - 1 # evaluate one determinant & make coefficients subresultants sign_value = correct_sign(n, m, s1, exp_deg, exp_deg - d) poly = row2poly(M[M.rows - 1, :], d, x) temp2 = LC(poly, x) poly = simplify((poly / temp2) * sign_value) # update s2 by inserting first row of M as needed row0 = M[0, :] for i in range(deg_g - d): s2[r + i, :] = rotate_r(row0, r + i) r = r + deg_g - d # update s2 by inserting last row of M as needed row1 = rotate_l(M[M.rows - 1, :], deg_f - d) row1 = (row1 / temp2) * sign_value for i in range(deg_g - d): s2[r + i, :] = rotate_r(row1, r + i) r = r + deg_g - d # update degrees deg_f, deg_g = deg_g, d # append poly with subresultant coeffs sr_list.append(poly) # final touches to print the s2 matrix if method != 0 and s2.rows > 2: s2 = final_touches(s2, r, deg_g) pprint(s2) elif method != 0 and s2.rows == 2: s2[1, :] = rotate_r(s2.row(1), 1) pprint(s2) return sr_list def subresultants_vv_2(p, q, x): """ p, q are polynomials in Z[x] (intended) or Q[x]. It is assumed that degree(p, x) >= degree(q, x). Computes the subresultant prs of p, q by triangularizing, in Z[x] or in Q[x], all the smaller matrices encountered in the process of triangularizing sylvester2, Sylvester's matrix of 1853; see references 1 and 2 for Van Vleck's method. If the sylvester2 matrix has big dimensions use this version, where sylvester2 is used implicitly. If you want to see the final, triangularized matrix sylvester2, then use the first version, subresultants_vv(p, q, x, 1). sylvester1, Sylvester's matrix of 1840, is also used to compute one subresultant per remainder; namely, that of the leading coefficient, in order to obtain the correct sign and to ``force'' the remainder coefficients to become subresultants. If the subresultant prs is complete, then it coincides with the Euclidean sequence of the polynomials p, q. References ========== 1. Akritas, A. G.: ``A new method for computing polynomial greatest common divisors and polynomial remainder sequences.'' Numerische MatheMatik 52, 119-127, 1988. 2. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``On a Theorem by Van Vleck Regarding Sturm Sequences.'' Serdica Journal of Computing, 7, No 4, 101–134, 2013. 3. Akritas, A. G.:``Three New Methods for Computing Subresultant Polynomial Remainder Sequences (PRS’s).'' Serdica Journal of Computing 9(1) (2015), 1-26. """ # make sure neither p nor q is 0 if p == 0 or q == 0: return [p, q] # make sure proper degrees f, g = p, q n = deg_f = degree(f, x) m = deg_g = degree(g, x) if n == 0 and m == 0: return [f, g] if n < m: n, m, deg_f, deg_g, f, g = m, n, deg_g, deg_f, g, f if n > 0 and m == 0: return [f, g] # initialize s1 = sylvester(f, g, x, 1) sr_list = [f, g] # subresultant list col_num = 2 * n # columns in sylvester2 # make two rows (row0, row1) of poly coefficients row0 = Poly(f, x, domain = QQ).all_coeffs() leng0 = len(row0) for i in range(col_num - leng0): row0.append(0) row0 = Matrix([row0]) row1 = Poly(g,x, domain = QQ).all_coeffs() leng1 = len(row1) for i in range(col_num - leng1): row1.append(0) row1 = Matrix([row1]) # main loop while deg_g > 0: # create a small matrix M, and triangularize it M = create_ma(deg_f, deg_g, row1, row0, col_num) for i in range(deg_f - deg_g + 1): M1 = pivot(M, i, i) M = M1[:, :] # treat last row of M as poly; find its degree d = find_degree(M, deg_f) if d == None: return sr_list exp_deg = deg_g - 1 # evaluate one determinant & make coefficients subresultants sign_value = correct_sign(n, m, s1, exp_deg, exp_deg - d) poly = row2poly(M[M.rows - 1, :], d, x) poly = simplify((poly / LC(poly, x)) * sign_value) # append poly with subresultant coeffs sr_list.append(poly) # update degrees and rows deg_f, deg_g = deg_g, d row0 = row1 row1 = Poly(poly, x, domain = QQ).all_coeffs() leng1 = len(row1) for i in range(col_num - leng1): row1.append(0) row1 = Matrix([row1]) return sr_list
2ea0842d270282ea85c2f02054176591e4b368df1488aca09cd606d72ce015aa	"""Sparse polynomial rings. """ from __future__ import print_function, division from operator import add, mul, lt, le, gt, ge from types import GeneratorType from sympy.core.compatibility import is_sequence, reduce, string_types, range from sympy.core.expr import Expr from sympy.core.numbers import igcd, oo from sympy.core.symbol import Symbol, symbols as _symbols from sympy.core.sympify import CantSympify, sympify from sympy.ntheory.multinomial import multinomial_coefficients from sympy.polys.compatibility import IPolys from sympy.polys.constructor import construct_domain from sympy.polys.densebasic import dmp_to_dict, dmp_from_dict from sympy.polys.domains.domainelement import DomainElement from sympy.polys.domains.polynomialring import PolynomialRing from sympy.polys.heuristicgcd import heugcd from sympy.polys.monomials import MonomialOps from sympy.polys.orderings import lex from sympy.polys.polyerrors import ( CoercionFailed, GeneratorsError, ExactQuotientFailed, MultivariatePolynomialError) from sympy.polys.polyoptions import (Domain as DomainOpt, Order as OrderOpt, build_options) from sympy.polys.polyutils import (expr_from_dict, _dict_reorder, _parallel_dict_from_expr) from sympy.printing.defaults import DefaultPrinting from sympy.utilities import public from sympy.utilities.magic import pollute @public def ring(symbols, domain, order=lex): """Construct a polynomial ring returning ``(ring, x_1, ..., x_n)``. Parameters ========== symbols : str Symbol/Expr or sequence of str, Symbol/Expr (non-empty) domain : :class: `Domain` or coercible order : :class:, optional `Order` or coercible, optional, defaults to ``lex`` Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> from sympy.polys.orderings import lex >>> R, x, y, z = ring("x,y,z", ZZ, lex) >>> R Polynomial ring in x, y, z over ZZ with lex order >>> x + y + z x + y + z >>> type(_) <class 'sympy.polys.rings.PolyElement'> """ _ring = PolyRing(symbols, domain, order) return (_ring,) + _ring.gens @public def xring(symbols, domain, order=lex): """Construct a polynomial ring returning ``(ring, (x_1, ..., x_n))``. Parameters ========== symbols : str Symbol/Expr or sequence of str, Symbol/Expr (non-empty) domain : :class: `Domain` or coercible order : :class:, optional `Order` or coercible, optional, defaults to ``lex`` Examples ======== >>> from sympy.polys.rings import xring >>> from sympy.polys.domains import ZZ >>> from sympy.polys.orderings import lex >>> R, (x, y, z) = xring("x,y,z", ZZ, lex) >>> R Polynomial ring in x, y, z over ZZ with lex order >>> x + y + z x + y + z >>> type(_) <class 'sympy.polys.rings.PolyElement'> """ _ring = PolyRing(symbols, domain, order) return (_ring, _ring.gens) @public def vring(symbols, domain, order=lex): """Construct a polynomial ring and inject ``x_1, ..., x_n`` into the global namespace. Parameters ========== symbols : str Symbol/Expr or sequence of str, Symbol/Expr (non-empty) domain : :class: `Domain` or coercible order : :class:, optional `Order` or coercible, optional, defaults to ``lex`` Examples ======== >>> from sympy.polys.rings import vring >>> from sympy.polys.domains import ZZ >>> from sympy.polys.orderings import lex >>> vring("x,y,z", ZZ, lex) Polynomial ring in x, y, z over ZZ with lex order >>> x + y + z x + y + z >>> type(_) <class 'sympy.polys.rings.PolyElement'> """ _ring = PolyRing(symbols, domain, order) pollute([ sym.name for sym in _ring.symbols ], _ring.gens) return _ring @public def sring(exprs, symbols, options): """Construct a ring deriving generators and domain from options and input expressions. Parameters ========== exprs : :class: `Expr` or sequence of :class:`Expr` (sympifiable) symbols : sequence of :class:`Symbol`/:class:`Expr` options : keyword arguments understood by :class:`Options` Examples ======== >>> from sympy.core import symbols >>> from sympy.polys.rings import sring >>> from sympy.polys.domains import ZZ >>> from sympy.polys.orderings import lex >>> x, y, z = symbols("x,y,z") >>> R, f = sring(x + 2y + 3z) >>> R Polynomial ring in x, y, z over ZZ with lex order >>> f x + 2y + 3z >>> type(_) <class 'sympy.polys.rings.PolyElement'> """ single = False if not is_sequence(exprs): exprs, single = [exprs], True exprs = list(map(sympify, exprs)) opt = build_options(symbols, options) # TODO: rewrite this so that it doesn't use expand() (see poly()). reps, opt = _parallel_dict_from_expr(exprs, opt) if opt.domain is None: # NOTE: this is inefficient because construct_domain() automatically # performs conversion to the target domain. It shouldn't do this. coeffs = sum([ list(rep.values()) for rep in reps ], []) opt.domain, _ = construct_domain(coeffs, opt=opt) _ring = PolyRing(opt.gens, opt.domain, opt.order) polys = list(map(_ring.from_dict, reps)) if single: return (_ring, polys[0]) else: return (_ring, polys) def _parse_symbols(symbols): if isinstance(symbols, string_types): return _symbols(symbols, seq=True) if symbols else () elif isinstance(symbols, Expr): return (symbols,) elif is_sequence(symbols): if all(isinstance(s, string_types) for s in symbols): return _symbols(symbols) elif all(isinstance(s, Expr) for s in symbols): return symbols raise GeneratorsError("expected a string, Symbol or expression or a non-empty sequence of strings, Symbols or expressions") _ring_cache = {} class PolyRing(DefaultPrinting, IPolys): """Multivariate distributed polynomial ring. """ def __new__(cls, symbols, domain, order=lex): symbols = tuple(_parse_symbols(symbols)) ngens = len(symbols) domain = DomainOpt.preprocess(domain) order = OrderOpt.preprocess(order) _hash_tuple = (cls.__name__, symbols, ngens, domain, order) obj = _ring_cache.get(_hash_tuple) if obj is None: if domain.is_Composite and set(symbols) & set(domain.symbols): raise GeneratorsError("polynomial ring and it's ground domain share generators") obj = object.__new__(cls) obj._hash_tuple = _hash_tuple obj._hash = hash(_hash_tuple) obj.dtype = type("PolyElement", (PolyElement,), {"ring": obj}) obj.symbols = symbols obj.ngens = ngens obj.domain = domain obj.order = order obj.zero_monom = (0,)ngens obj.gens = obj._gens() obj._gens_set = set(obj.gens) obj._one = [(obj.zero_monom, domain.one)] if ngens: # These expect monomials in at least one variable codegen = MonomialOps(ngens) obj.monomial_mul = codegen.mul() obj.monomial_pow = codegen.pow() obj.monomial_mulpow = codegen.mulpow() obj.monomial_ldiv = codegen.ldiv() obj.monomial_div = codegen.div() obj.monomial_lcm = codegen.lcm() obj.monomial_gcd = codegen.gcd() else: monunit = lambda a, b: () obj.monomial_mul = monunit obj.monomial_pow = monunit obj.monomial_mulpow = lambda a, b, c: () obj.monomial_ldiv = monunit obj.monomial_div = monunit obj.monomial_lcm = monunit obj.monomial_gcd = monunit if order is lex: obj.leading_expv = lambda f: max(f) else: obj.leading_expv = lambda f: max(f, key=order) for symbol, generator in zip(obj.symbols, obj.gens): if isinstance(symbol, Symbol): name = symbol.name if not hasattr(obj, name): setattr(obj, name, generator) _ring_cache[_hash_tuple] = obj return obj def _gens(self): """Return a list of polynomial generators. """ one = self.domain.one _gens = [] for i in range(self.ngens): expv = self.monomial_basis(i) poly = self.zero poly[expv] = one _gens.append(poly) return tuple(_gens) def __getnewargs__(self): return (self.symbols, self.domain, self.order) def __getstate__(self): state = self.__dict__.copy() del state["leading_expv"] for key, value in state.items(): if key.startswith("monomial_"): del state[key] return state def __hash__(self): return self._hash def __eq__(self, other): return isinstance(other, PolyRing) and \ (self.symbols, self.domain, self.ngens, self.order) == \ (other.symbols, other.domain, other.ngens, other.order) def __ne__(self, other): return not self == other def clone(self, symbols=None, domain=None, order=None): return self.__class__(symbols or self.symbols, domain or self.domain, order or self.order) def monomial_basis(self, i): """Return the ith-basis element. """ basis = [0]self.ngens basis[i] = 1 return tuple(basis) @property def zero(self): return self.dtype() @property def one(self): return self.dtype(self._one) def domain_new(self, element, orig_domain=None): return self.domain.convert(element, orig_domain) def ground_new(self, coeff): return self.term_new(self.zero_monom, coeff) def term_new(self, monom, coeff): coeff = self.domain_new(coeff) poly = self.zero if coeff: poly[monom] = coeff return poly def ring_new(self, element): if isinstance(element, PolyElement): if self == element.ring: return element elif isinstance(self.domain, PolynomialRing) and self.domain.ring == element.ring: return self.ground_new(element) else: raise NotImplementedError("conversion") elif isinstance(element, string_types): raise NotImplementedError("parsing") elif isinstance(element, dict): return self.from_dict(element) elif isinstance(element, list): try: return self.from_terms(element) except ValueError: return self.from_list(element) elif isinstance(element, Expr): return self.from_expr(element) else: return self.ground_new(element) __call__ = ring_new def from_dict(self, element): domain_new = self.domain_new poly = self.zero for monom, coeff in element.items(): coeff = domain_new(coeff) if coeff: poly[monom] = coeff return poly def from_terms(self, element): return self.from_dict(dict(element)) def from_list(self, element): return self.from_dict(dmp_to_dict(element, self.ngens-1, self.domain)) def _rebuild_expr(self, expr, mapping): domain = self.domain def _rebuild(expr): generator = mapping.get(expr) if generator is not None: return generator elif expr.is_Add: return reduce(add, list(map(_rebuild, expr.args))) elif expr.is_Mul: return reduce(mul, list(map(_rebuild, expr.args))) elif expr.is_Pow and expr.exp.is_Integer and expr.exp >= 0: return _rebuild(expr.base)int(expr.exp) else: return domain.convert(expr) return _rebuild(sympify(expr)) def from_expr(self, expr): mapping = dict(list(zip(self.symbols, self.gens))) try: poly = self._rebuild_expr(expr, mapping) except CoercionFailed: raise ValueError("expected an expression convertible to a polynomial in %s, got %s" % (self, expr)) else: return self.ring_new(poly) def index(self, gen): """Compute index of ``gen`` in ``self.gens``. """ if gen is None: if self.ngens: i = 0 else: i = -1 # indicate impossible choice elif isinstance(gen, int): i = gen if 0 <= i and i < self.ngens: pass elif -self.ngens <= i and i <= -1: i = -i - 1 else: raise ValueError("invalid generator index: %s" % gen) elif isinstance(gen, self.dtype): try: i = self.gens.index(gen) except ValueError: raise ValueError("invalid generator: %s" % gen) elif isinstance(gen, string_types): try: i = self.symbols.index(gen) except ValueError: raise ValueError("invalid generator: %s" % gen) else: raise ValueError("expected a polynomial generator, an integer, a string or None, got %s" % gen) return i def drop(self, gens): """Remove specified generators from this ring. """ indices = set(map(self.index, gens)) symbols = [ s for i, s in enumerate(self.symbols) if i not in indices ] if not symbols: return self.domain else: return self.clone(symbols=symbols) def __getitem__(self, key): symbols = self.symbols[key] if not symbols: return self.domain else: return self.clone(symbols=symbols) def to_ground(self): # TODO: should AlgebraicField be a Composite domain? if self.domain.is_Composite or hasattr(self.domain, 'domain'): return self.clone(domain=self.domain.domain) else: raise ValueError("%s is not a composite domain" % self.domain) def to_domain(self): return PolynomialRing(self) def to_field(self): from sympy.polys.fields import FracField return FracField(self.symbols, self.domain, self.order) @property def is_univariate(self): return len(self.gens) == 1 @property def is_multivariate(self): return len(self.gens) > 1 def add(self, objs): """ Add a sequence of polynomials or containers of polynomials. Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> R, x = ring("x", ZZ) >>> R.add([ x2 + 2i + 3 for i in range(4) ]) 4x2 + 24 >>> _.factor_list() (4, [(x2 + 6, 1)]) """ p = self.zero for obj in objs: if is_sequence(obj, include=GeneratorType): p += self.add(obj) else: p += obj return p def mul(self, objs): """ Multiply a sequence of polynomials or containers of polynomials. Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> R, x = ring("x", ZZ) >>> R.mul([ x2 + 2i + 3 for i in range(4) ]) x*8 + 24x*6 + 206x*4 + 744x2 + 945 >>> _.factor_list() (1, [(x2 + 3, 1), (x2 + 5, 1), (x2 + 7, 1), (x*2 + 9, 1)]) """ p = self.one for obj in objs: if is_sequence(obj, include=GeneratorType): p = self.mul(obj) else: p = obj return p def drop_to_ground(self, gens): r""" Remove specified generators from the ring and inject them into its domain. """ indices = set(map(self.index, gens)) symbols = [s for i, s in enumerate(self.symbols) if i not in indices] gens = [gen for i, gen in enumerate(self.gens) if i not in indices] if not symbols: return self else: return self.clone(symbols=symbols, domain=self.drop(gens)) def compose(self, other): """Add the generators of ``other`` to ``self``""" if self != other: syms = set(self.symbols).union(set(other.symbols)) return self.clone(symbols=list(syms)) else: return self def add_gens(self, symbols): """Add the elements of ``symbols`` as generators to ``self``""" syms = set(self.symbols).union(set(symbols)) return self.clone(symbols=list(syms)) class PolyElement(DomainElement, DefaultPrinting, CantSympify, dict): """Element of multivariate distributed polynomial ring. """ def new(self, init): return self.__class__(init) def parent(self): return self.ring.to_domain() def __getnewargs__(self): return (self.ring, list(self.iterterms())) _hash = None def __hash__(self): # XXX: This computes a hash of a dictionary, but currently we don't # protect dictionary from being changed so any use site modifications # will make hashing go wrong. Use this feature with caution until we # figure out how to make a safe API without compromising speed of this # low-level class. _hash = self._hash if _hash is None: self._hash = _hash = hash((self.ring, frozenset(self.items()))) return _hash def copy(self): """Return a copy of polynomial self. Polynomials are mutable; if one is interested in preserving a polynomial, and one plans to use inplace operations, one can copy the polynomial. This method makes a shallow copy. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.rings import ring >>> R, x, y = ring('x, y', ZZ) >>> p = (x + y)2 >>> p1 = p.copy() >>> p2 = p >>> p[R.zero_monom] = 3 >>> p x2 + 2xy + y2 + 3 >>> p1 x2 + 2xy + y2 >>> p2 x2 + 2xy + y*2 + 3 """ return self.new(self) def set_ring(self, new_ring): if self.ring == new_ring: return self elif self.ring.symbols != new_ring.symbols: terms = list(zip(_dict_reorder(self, self.ring.symbols, new_ring.symbols))) return new_ring.from_terms(terms) else: return new_ring.from_dict(self) def as_expr(self, symbols): if symbols and len(symbols) != self.ring.ngens: raise ValueError("not enough symbols, expected %s got %s" % (self.ring.ngens, len(symbols))) else: symbols = self.ring.symbols return expr_from_dict(self.as_expr_dict(), symbols) def as_expr_dict(self): to_sympy = self.ring.domain.to_sympy return {monom: to_sympy(coeff) for monom, coeff in self.iterterms()} def clear_denoms(self): domain = self.ring.domain if not domain.is_Field or not domain.has_assoc_Ring: return domain.one, self ground_ring = domain.get_ring() common = ground_ring.one lcm = ground_ring.lcm denom = domain.denom for coeff in self.values(): common = lcm(common, denom(coeff)) poly = self.new([ (k, vcommon) for k, v in self.items() ]) return common, poly def strip_zero(self): """Eliminate monomials with zero coefficient. """ for k, v in list(self.items()): if not v: del self[k] def __eq__(p1, p2): """Equality test for polynomials. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.rings import ring >>> _, x, y = ring('x, y', ZZ) >>> p1 = (x + y)2 + (x - y)2 >>> p1 == 4xy False >>> p1 == 2(x2 + y2) True """ if not p2: return not p1 elif isinstance(p2, PolyElement) and p2.ring == p1.ring: return dict.__eq__(p1, p2) elif len(p1) > 1: return False else: return p1.get(p1.ring.zero_monom) == p2 def __ne__(p1, p2): return not p1 == p2 def almosteq(p1, p2, tolerance=None): """Approximate equality test for polynomials. """ ring = p1.ring if isinstance(p2, ring.dtype): if set(p1.keys()) != set(p2.keys()): return False almosteq = ring.domain.almosteq for k in p1.keys(): if not almosteq(p1[k], p2[k], tolerance): return False else: return True elif len(p1) > 1: return False else: try: p2 = ring.domain.convert(p2) except CoercionFailed: return False else: return ring.domain.almosteq(p1.const(), p2, tolerance) def sort_key(self): return (len(self), self.terms()) def _cmp(p1, p2, op): if isinstance(p2, p1.ring.dtype): return op(p1.sort_key(), p2.sort_key()) else: return NotImplemented def __lt__(p1, p2): return p1._cmp(p2, lt) def __le__(p1, p2): return p1._cmp(p2, le) def __gt__(p1, p2): return p1._cmp(p2, gt) def __ge__(p1, p2): return p1._cmp(p2, ge) def _drop(self, gen): ring = self.ring i = ring.index(gen) if ring.ngens == 1: return i, ring.domain else: symbols = list(ring.symbols) del symbols[i] return i, ring.clone(symbols=symbols) def drop(self, gen): i, ring = self._drop(gen) if self.ring.ngens == 1: if self.is_ground: return self.coeff(1) else: raise ValueError("can't drop %s" % gen) else: poly = ring.zero for k, v in self.items(): if k[i] == 0: K = list(k) del K[i] poly[tuple(K)] = v else: raise ValueError("can't drop %s" % gen) return poly def _drop_to_ground(self, gen): ring = self.ring i = ring.index(gen) symbols = list(ring.symbols) del symbols[i] return i, ring.clone(symbols=symbols, domain=ring[i]) def drop_to_ground(self, gen): if self.ring.ngens == 1: raise ValueError("can't drop only generator to ground") i, ring = self._drop_to_ground(gen) poly = ring.zero gen = ring.domain.gens[0] for monom, coeff in self.iterterms(): mon = monom[:i] + monom[i+1:] if not mon in poly: poly[mon] = (genmonom[i]).mul_ground(coeff) else: poly[mon] += (genmonom[i]).mul_ground(coeff) return poly def to_dense(self): return dmp_from_dict(self, self.ring.ngens-1, self.ring.domain) def to_dict(self): return dict(self) def str(self, printer, precedence, exp_pattern, mul_symbol): if not self: return printer._print(self.ring.domain.zero) prec_mul = precedence["Mul"] prec_atom = precedence["Atom"] ring = self.ring symbols = ring.symbols ngens = ring.ngens zm = ring.zero_monom sexpvs = [] for expv, coeff in self.terms(): positive = ring.domain.is_positive(coeff) sign = " + " if positive else " - " sexpvs.append(sign) if expv == zm: scoeff = printer._print(coeff) if scoeff.startswith("-"): scoeff = scoeff[1:] else: if not positive: coeff = -coeff if coeff != 1: scoeff = printer.parenthesize(coeff, prec_mul, strict=True) else: scoeff = '' sexpv = [] for i in range(ngens): exp = expv[i] if not exp: continue symbol = printer.parenthesize(symbols[i], prec_atom, strict=True) if exp != 1: if exp != int(exp) or exp < 0: sexp = printer.parenthesize(exp, prec_atom, strict=False) else: sexp = exp sexpv.append(exp_pattern % (symbol, sexp)) else: sexpv.append('%s' % symbol) if scoeff: sexpv = [scoeff] + sexpv sexpvs.append(mul_symbol.join(sexpv)) if sexpvs[0] in [" + ", " - "]: head = sexpvs.pop(0) if head == " - ": sexpvs.insert(0, "-") return "".join(sexpvs) @property def is_generator(self): return self in self.ring._gens_set @property def is_ground(self): return not self or (len(self) == 1 and self.ring.zero_monom in self) @property def is_monomial(self): return not self or (len(self) == 1 and self.LC == 1) @property def is_term(self): return len(self) <= 1 @property def is_negative(self): return self.ring.domain.is_negative(self.LC) @property def is_positive(self): return self.ring.domain.is_positive(self.LC) @property def is_nonnegative(self): return self.ring.domain.is_nonnegative(self.LC) @property def is_nonpositive(self): return self.ring.domain.is_nonpositive(self.LC) @property def is_zero(f): return not f @property def is_one(f): return f == f.ring.one @property def is_monic(f): return f.ring.domain.is_one(f.LC) @property def is_primitive(f): return f.ring.domain.is_one(f.content()) @property def is_linear(f): return all(sum(monom) <= 1 for monom in f.itermonoms()) @property def is_quadratic(f): return all(sum(monom) <= 2 for monom in f.itermonoms()) @property def is_squarefree(f): if not f.ring.ngens: return True return f.ring.dmp_sqf_p(f) @property def is_irreducible(f): if not f.ring.ngens: return True return f.ring.dmp_irreducible_p(f) @property def is_cyclotomic(f): if f.ring.is_univariate: return f.ring.dup_cyclotomic_p(f) else: raise MultivariatePolynomialError("cyclotomic polynomial") def __neg__(self): return self.new([ (monom, -coeff) for monom, coeff in self.iterterms() ]) def __pos__(self): return self def __add__(p1, p2): """Add two polynomials. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.rings import ring >>> _, x, y = ring('x, y', ZZ) >>> (x + y)2 + (x - y)2 2x2 + 2y2 """ if not p2: return p1.copy() ring = p1.ring if isinstance(p2, ring.dtype): p = p1.copy() get = p.get zero = ring.domain.zero for k, v in p2.items(): v = get(k, zero) + v if v: p[k] = v else: del p[k] return p elif isinstance(p2, PolyElement): if isinstance(ring.domain, PolynomialRing) and ring.domain.ring == p2.ring: pass elif isinstance(p2.ring.domain, PolynomialRing) and p2.ring.domain.ring == ring: return p2.__radd__(p1) else: return NotImplemented try: cp2 = ring.domain_new(p2) except CoercionFailed: return NotImplemented else: p = p1.copy() if not cp2: return p zm = ring.zero_monom if zm not in p1.keys(): p[zm] = cp2 else: if p2 == -p[zm]: del p[zm] else: p[zm] += cp2 return p def __radd__(p1, n): p = p1.copy() if not n: return p ring = p1.ring try: n = ring.domain_new(n) except CoercionFailed: return NotImplemented else: zm = ring.zero_monom if zm not in p1.keys(): p[zm] = n else: if n == -p[zm]: del p[zm] else: p[zm] += n return p def __sub__(p1, p2): """Subtract polynomial p2 from p1. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.rings import ring >>> _, x, y = ring('x, y', ZZ) >>> p1 = x + y2 >>> p2 = xy + y2 >>> p1 - p2 -xy + x """ if not p2: return p1.copy() ring = p1.ring if isinstance(p2, ring.dtype): p = p1.copy() get = p.get zero = ring.domain.zero for k, v in p2.items(): v = get(k, zero) - v if v: p[k] = v else: del p[k] return p elif isinstance(p2, PolyElement): if isinstance(ring.domain, PolynomialRing) and ring.domain.ring == p2.ring: pass elif isinstance(p2.ring.domain, PolynomialRing) and p2.ring.domain.ring == ring: return p2.__rsub__(p1) else: return NotImplemented try: p2 = ring.domain_new(p2) except CoercionFailed: return NotImplemented else: p = p1.copy() zm = ring.zero_monom if zm not in p1.keys(): p[zm] = -p2 else: if p2 == p[zm]: del p[zm] else: p[zm] -= p2 return p def __rsub__(p1, n): """n - p1 with n convertible to the coefficient domain. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.rings import ring >>> _, x, y = ring('x, y', ZZ) >>> p = x + y >>> 4 - p -x - y + 4 """ ring = p1.ring try: n = ring.domain_new(n) except CoercionFailed: return NotImplemented else: p = ring.zero for expv in p1: p[expv] = -p1[expv] p += n return p def __mul__(p1, p2): """Multiply two polynomials. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> _, x, y = ring('x, y', QQ) >>> p1 = x + y >>> p2 = x - y >>> p1p2 x2 - y2 """ ring = p1.ring p = ring.zero if not p1 or not p2: return p elif isinstance(p2, ring.dtype): get = p.get zero = ring.domain.zero monomial_mul = ring.monomial_mul p2it = list(p2.items()) for exp1, v1 in p1.items(): for exp2, v2 in p2it: exp = monomial_mul(exp1, exp2) p[exp] = get(exp, zero) + v1v2 p.strip_zero() return p elif isinstance(p2, PolyElement): if isinstance(ring.domain, PolynomialRing) and ring.domain.ring == p2.ring: pass elif isinstance(p2.ring.domain, PolynomialRing) and p2.ring.domain.ring == ring: return p2.__rmul__(p1) else: return NotImplemented try: p2 = ring.domain_new(p2) except CoercionFailed: return NotImplemented else: for exp1, v1 in p1.items(): v = v1p2 if v: p[exp1] = v return p def __rmul__(p1, p2): """p2 p1 with p2 in the coefficient domain of p1. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.rings import ring >>> _, x, y = ring('x, y', ZZ) >>> p = x + y >>> 4 * p 4x + 4y """ p = p1.ring.zero if not p2: return p try: p2 = p.ring.domain_new(p2) except CoercionFailed: return NotImplemented else: for exp1, v1 in p1.items(): v = p2v1 if v: p[exp1] = v return p def __pow__(self, n): """raise polynomial to power `n` Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.rings import ring >>> _, x, y = ring('x, y', ZZ) >>> p = x + y2 >>> p3 x3 + 3x*2y*2 + 3xy4 + y6 """ ring = self.ring if not n: if self: return ring.one else: raise ValueError("00") elif len(self) == 1: monom, coeff = list(self.items())[0] p = ring.zero if coeff == 1: p[ring.monomial_pow(monom, n)] = coeff else: p[ring.monomial_pow(monom, n)] = coeffn return p # For ring series, we need negative and rational exponent support only # with monomials. n = int(n) if n < 0: raise ValueError("Negative exponent") elif n == 1: return self.copy() elif n == 2: return self.square() elif n == 3: return selfself.square() elif len(self) <= 5: # TODO: use an actuall density measure return self._pow_multinomial(n) else: return self._pow_generic(n) def _pow_generic(self, n): p = self.ring.one c = self while True: if n & 1: p = pc n -= 1 if not n: break c = c.square() n = n // 2 return p def _pow_multinomial(self, n): multinomials = list(multinomial_coefficients(len(self), n).items()) monomial_mulpow = self.ring.monomial_mulpow zero_monom = self.ring.zero_monom terms = list(self.iterterms()) zero = self.ring.domain.zero poly = self.ring.zero for multinomial, multinomial_coeff in multinomials: product_monom = zero_monom product_coeff = multinomial_coeff for exp, (monom, coeff) in zip(multinomial, terms): if exp: product_monom = monomial_mulpow(product_monom, monom, exp) product_coeff = coeffexp monom = tuple(product_monom) coeff = product_coeff coeff = poly.get(monom, zero) + coeff if coeff: poly[monom] = coeff else: del poly[monom] return poly def square(self): """square of a polynomial Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> _, x, y = ring('x, y', ZZ) >>> p = x + y2 >>> p.square() x*2 + 2xy2 + y4 """ ring = self.ring p = ring.zero get = p.get keys = list(self.keys()) zero = ring.domain.zero monomial_mul = ring.monomial_mul for i in range(len(keys)): k1 = keys[i] pk = self[k1] for j in range(i): k2 = keys[j] exp = monomial_mul(k1, k2) p[exp] = get(exp, zero) + pkself[k2] p = p.imul_num(2) get = p.get for k, v in self.items(): k2 = monomial_mul(k, k) p[k2] = get(k2, zero) + v*2 p.strip_zero() return p def __divmod__(p1, p2): ring = p1.ring if not p2: raise ZeroDivisionError("polynomial division") elif isinstance(p2, ring.dtype): return p1.div(p2) elif isinstance(p2, PolyElement): if isinstance(ring.domain, PolynomialRing) and ring.domain.ring == p2.ring: pass elif isinstance(p2.ring.domain, PolynomialRing) and p2.ring.domain.ring == ring: return p2.__rdivmod__(p1) else: return NotImplemented try: p2 = ring.domain_new(p2) except CoercionFailed: return NotImplemented else: return (p1.quo_ground(p2), p1.rem_ground(p2)) def __rdivmod__(p1, p2): return NotImplemented def __mod__(p1, p2): ring = p1.ring if not p2: raise ZeroDivisionError("polynomial division") elif isinstance(p2, ring.dtype): return p1.rem(p2) elif isinstance(p2, PolyElement): if isinstance(ring.domain, PolynomialRing) and ring.domain.ring == p2.ring: pass elif isinstance(p2.ring.domain, PolynomialRing) and p2.ring.domain.ring == ring: return p2.__rmod__(p1) else: return NotImplemented try: p2 = ring.domain_new(p2) except CoercionFailed: return NotImplemented else: return p1.rem_ground(p2) def __rmod__(p1, p2): return NotImplemented def __truediv__(p1, p2): ring = p1.ring if not p2: raise ZeroDivisionError("polynomial division") elif isinstance(p2, ring.dtype): if p2.is_monomial: return p1(p2*(-1)) else: return p1.quo(p2) elif isinstance(p2, PolyElement): if isinstance(ring.domain, PolynomialRing) and ring.domain.ring == p2.ring: pass elif isinstance(p2.ring.domain, PolynomialRing) and p2.ring.domain.ring == ring: return p2.__rtruediv__(p1) else: return NotImplemented try: p2 = ring.domain_new(p2) except CoercionFailed: return NotImplemented else: return p1.quo_ground(p2) def __rtruediv__(p1, p2): return NotImplemented __floordiv__ = __div__ = __truediv__ __rfloordiv__ = __rdiv__ = __rtruediv__ # TODO: use // (__floordiv__) for exquo()? def _term_div(self): zm = self.ring.zero_monom domain = self.ring.domain domain_quo = domain.quo monomial_div = self.ring.monomial_div if domain.is_Field: def term_div(a_lm_a_lc, b_lm_b_lc): a_lm, a_lc = a_lm_a_lc b_lm, b_lc = b_lm_b_lc if b_lm == zm: # apparently this is a very common case monom = a_lm else: monom = monomial_div(a_lm, b_lm) if monom is not None: return monom, domain_quo(a_lc, b_lc) else: return None else: def term_div(a_lm_a_lc, b_lm_b_lc): a_lm, a_lc = a_lm_a_lc b_lm, b_lc = b_lm_b_lc if b_lm == zm: # apparently this is a very common case monom = a_lm else: monom = monomial_div(a_lm, b_lm) if not (monom is None or a_lc % b_lc): return monom, domain_quo(a_lc, b_lc) else: return None return term_div def div(self, fv): """Division algorithm, see [CLO] p64. fv array of polynomials return qv, r such that self = sum(fv[i]qv[i]) + r All polynomials are required not to be Laurent polynomials. Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> _, x, y = ring('x, y', ZZ) >>> f = x3 >>> f0 = x - y2 >>> f1 = x - y >>> qv, r = f.div((f0, f1)) >>> qv[0] x*2 + xy2 + y4 >>> qv[1] 0 >>> r y*6 """ ring = self.ring ret_single = False if isinstance(fv, PolyElement): ret_single = True fv = [fv] if any(not f for f in fv): raise ZeroDivisionError("polynomial division") if not self: if ret_single: return ring.zero, ring.zero else: return [], ring.zero for f in fv: if f.ring != ring: raise ValueError('self and f must have the same ring') s = len(fv) qv = [ring.zero for i in range(s)] p = self.copy() r = ring.zero term_div = self._term_div() expvs = [fx.leading_expv() for fx in fv] while p: i = 0 divoccurred = 0 while i < s and divoccurred == 0: expv = p.leading_expv() term = term_div((expv, p[expv]), (expvs[i], fv[i][expvs[i]])) if term is not None: expv1, c = term qv[i] = qv[i]._iadd_monom((expv1, c)) p = p._iadd_poly_monom(fv[i], (expv1, -c)) divoccurred = 1 else: i += 1 if not divoccurred: expv = p.leading_expv() r = r._iadd_monom((expv, p[expv])) del p[expv] if expv == ring.zero_monom: r += p if ret_single: if not qv: return ring.zero, r else: return qv[0], r else: return qv, r def rem(self, G): f = self if isinstance(G, PolyElement): G = [G] if any(not g for g in G): raise ZeroDivisionError("polynomial division") ring = f.ring domain = ring.domain zero = domain.zero monomial_mul = ring.monomial_mul r = ring.zero term_div = f._term_div() ltf = f.LT f = f.copy() get = f.get while f: for g in G: tq = term_div(ltf, g.LT) if tq is not None: m, c = tq for mg, cg in g.iterterms(): m1 = monomial_mul(mg, m) c1 = get(m1, zero) - ccg if not c1: del f[m1] else: f[m1] = c1 ltm = f.leading_expv() if ltm is not None: ltf = ltm, f[ltm] break else: ltm, ltc = ltf if ltm in r: r[ltm] += ltc else: r[ltm] = ltc del f[ltm] ltm = f.leading_expv() if ltm is not None: ltf = ltm, f[ltm] return r def quo(f, G): return f.div(G)[0] def exquo(f, G): q, r = f.div(G) if not r: return q else: raise ExactQuotientFailed(f, G) def _iadd_monom(self, mc): """add to self the monomial coeffx0i0x1*i1... unless self is a generator -- then just return the sum of the two. mc is a tuple, (monom, coeff), where monomial is (i0, i1, ...) Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> _, x, y = ring('x, y', ZZ) >>> p = x*4 + 2y >>> m = (1, 2) >>> p1 = p._iadd_monom((m, 5)) >>> p1 x*4 + 5xy2 + 2y >>> p1 is p True >>> p = x >>> p1 = p._iadd_monom((m, 5)) >>> p1 5xy*2 + x >>> p1 is p False """ if self in self.ring._gens_set: cpself = self.copy() else: cpself = self expv, coeff = mc c = cpself.get(expv) if c is None: cpself[expv] = coeff else: c += coeff if c: cpself[expv] = c else: del cpself[expv] return cpself def _iadd_poly_monom(self, p2, mc): """add to self the product of (p)(coeffx0i0x1*i1...) unless self is a generator -- then just return the sum of the two. mc is a tuple, (monom, coeff), where monomial is (i0, i1, ...) Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> _, x, y, z = ring('x, y, z', ZZ) >>> p1 = x*4 + 2y >>> p2 = y + z >>> m = (1, 2, 3) >>> p1 = p1._iadd_poly_monom(p2, (m, 3)) >>> p1 x*4 + 3xy3z*3 + 3xy2z*4 + 2y """ p1 = self if p1 in p1.ring._gens_set: p1 = p1.copy() (m, c) = mc get = p1.get zero = p1.ring.domain.zero monomial_mul = p1.ring.monomial_mul for k, v in p2.items(): ka = monomial_mul(k, m) coeff = get(ka, zero) + vc if coeff: p1[ka] = coeff else: del p1[ka] return p1 def degree(f, x=None): """ The leading degree in ``x`` or the main variable. Note that the degree of 0 is negative infinity (the SymPy object -oo). """ i = f.ring.index(x) if not f: return -oo elif i < 0: return 0 else: return max([ monom[i] for monom in f.itermonoms() ]) def degrees(f): """ A tuple containing leading degrees in all variables. Note that the degree of 0 is negative infinity (the SymPy object -oo) """ if not f: return (-oo,)f.ring.ngens else: return tuple(map(max, list(zip(f.itermonoms())))) def tail_degree(f, x=None): """ The tail degree in ``x`` or the main variable. Note that the degree of 0 is negative infinity (the SymPy object -oo) """ i = f.ring.index(x) if not f: return -oo elif i < 0: return 0 else: return min([ monom[i] for monom in f.itermonoms() ]) def tail_degrees(f): """ A tuple containing tail degrees in all variables. Note that the degree of 0 is negative infinity (the SymPy object -oo) """ if not f: return (-oo,)f.ring.ngens else: return tuple(map(min, list(zip(f.itermonoms())))) def leading_expv(self): """Leading monomial tuple according to the monomial ordering. Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> _, x, y, z = ring('x, y, z', ZZ) >>> p = x4 + x3y + x*2z2 + z7 >>> p.leading_expv() (4, 0, 0) """ if self: return self.ring.leading_expv(self) else: return None def _get_coeff(self, expv): return self.get(expv, self.ring.domain.zero) def coeff(self, element): """ Returns the coefficient that stands next to the given monomial. Parameters ========== element : PolyElement (with ``is_monomial = True``) or 1 Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> _, x, y, z = ring("x,y,z", ZZ) >>> f = 3x2y - xyz + 7z3 + 23 >>> f.coeff(x2y) 3 >>> f.coeff(xy) 0 >>> f.coeff(1) 23 """ if element == 1: return self._get_coeff(self.ring.zero_monom) elif isinstance(element, self.ring.dtype): terms = list(element.iterterms()) if len(terms) == 1: monom, coeff = terms[0] if coeff == self.ring.domain.one: return self._get_coeff(monom) raise ValueError("expected a monomial, got %s" % element) def const(self): """Returns the constant coeffcient. """ return self._get_coeff(self.ring.zero_monom) @property def LC(self): return self._get_coeff(self.leading_expv()) @property def LM(self): expv = self.leading_expv() if expv is None: return self.ring.zero_monom else: return expv def leading_monom(self): """ Leading monomial as a polynomial element. Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> _, x, y = ring('x, y', ZZ) >>> (3xy + y2).leading_monom() xy """ p = self.ring.zero expv = self.leading_expv() if expv: p[expv] = self.ring.domain.one return p @property def LT(self): expv = self.leading_expv() if expv is None: return (self.ring.zero_monom, self.ring.domain.zero) else: return (expv, self._get_coeff(expv)) def leading_term(self): """Leading term as a polynomial element. Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> _, x, y = ring('x, y', ZZ) >>> (3xy + y*2).leading_term() 3xy """ p = self.ring.zero expv = self.leading_expv() if expv is not None: p[expv] = self[expv] return p def _sorted(self, seq, order): if order is None: order = self.ring.order else: order = OrderOpt.preprocess(order) if order is lex: return sorted(seq, key=lambda monom: monom[0], reverse=True) else: return sorted(seq, key=lambda monom: order(monom[0]), reverse=True) def coeffs(self, order=None): """Ordered list of polynomial coefficients. Parameters ========== order : :class:`Order` or coercible, optional Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> from sympy.polys.orderings import lex, grlex >>> _, x, y = ring("x, y", ZZ, lex) >>> f = xy*7 + 2x*2y*3 >>> f.coeffs() [2, 1] >>> f.coeffs(grlex) [1, 2] """ return [ coeff for _, coeff in self.terms(order) ] def monoms(self, order=None): """Ordered list of polynomial monomials. Parameters ========== order : :class:`Order` or coercible, optional Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> from sympy.polys.orderings import lex, grlex >>> _, x, y = ring("x, y", ZZ, lex) >>> f = xy*7 + 2x*2y*3 >>> f.monoms() [(2, 3), (1, 7)] >>> f.monoms(grlex) [(1, 7), (2, 3)] """ return [ monom for monom, _ in self.terms(order) ] def terms(self, order=None): """Ordered list of polynomial terms. Parameters ========== order : :class:`Order` or coercible, optional Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> from sympy.polys.orderings import lex, grlex >>> _, x, y = ring("x, y", ZZ, lex) >>> f = xy*7 + 2x*2y3 >>> f.terms() [((2, 3), 2), ((1, 7), 1)] >>> f.terms(grlex) [((1, 7), 1), ((2, 3), 2)] """ return self._sorted(list(self.items()), order) def itercoeffs(self): """Iterator over coefficients of a polynomial. """ return iter(self.values()) def itermonoms(self): """Iterator over monomials of a polynomial. """ return iter(self.keys()) def iterterms(self): """Iterator over terms of a polynomial. """ return iter(self.items()) def listcoeffs(self): """Unordered list of polynomial coefficients. """ return list(self.values()) def listmonoms(self): """Unordered list of polynomial monomials. """ return list(self.keys()) def listterms(self): """Unordered list of polynomial terms. """ return list(self.items()) def imul_num(p, c): """multiply inplace the polynomial p by an element in the coefficient ring, provided p is not one of the generators; else multiply not inplace Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> _, x, y = ring('x, y', ZZ) >>> p = x + y2 >>> p1 = p.imul_num(3) >>> p1 3x + 3y*2 >>> p1 is p True >>> p = x >>> p1 = p.imul_num(3) >>> p1 3x >>> p1 is p False """ if p in p.ring._gens_set: return pc if not c: p.clear() return for exp in p: p[exp] = c return p def content(f): """Returns GCD of polynomial's coefficients. """ domain = f.ring.domain cont = domain.zero gcd = domain.gcd for coeff in f.itercoeffs(): cont = gcd(cont, coeff) return cont def primitive(f): """Returns content and a primitive polynomial. """ cont = f.content() return cont, f.quo_ground(cont) def monic(f): """Divides all coefficients by the leading coefficient. """ if not f: return f else: return f.quo_ground(f.LC) def mul_ground(f, x): if not x: return f.ring.zero terms = [ (monom, coeffx) for monom, coeff in f.iterterms() ] return f.new(terms) def mul_monom(f, monom): monomial_mul = f.ring.monomial_mul terms = [ (monomial_mul(f_monom, monom), f_coeff) for f_monom, f_coeff in f.items() ] return f.new(terms) def mul_term(f, term): monom, coeff = term if not f or not coeff: return f.ring.zero elif monom == f.ring.zero_monom: return f.mul_ground(coeff) monomial_mul = f.ring.monomial_mul terms = [ (monomial_mul(f_monom, monom), f_coeffcoeff) for f_monom, f_coeff in f.items() ] return f.new(terms) def quo_ground(f, x): domain = f.ring.domain if not x: raise ZeroDivisionError('polynomial division') if not f or x == domain.one: return f if domain.is_Field: quo = domain.quo terms = [ (monom, quo(coeff, x)) for monom, coeff in f.iterterms() ] else: terms = [ (monom, coeff // x) for monom, coeff in f.iterterms() if not (coeff % x) ] return f.new(terms) def quo_term(f, term): monom, coeff = term if not coeff: raise ZeroDivisionError("polynomial division") elif not f: return f.ring.zero elif monom == f.ring.zero_monom: return f.quo_ground(coeff) term_div = f._term_div() terms = [ term_div(t, term) for t in f.iterterms() ] return f.new([ t for t in terms if t is not None ]) def trunc_ground(f, p): if f.ring.domain.is_ZZ: terms = [] for monom, coeff in f.iterterms(): coeff = coeff % p if coeff > p // 2: coeff = coeff - p terms.append((monom, coeff)) else: terms = [ (monom, coeff % p) for monom, coeff in f.iterterms() ] poly = f.new(terms) poly.strip_zero() return poly rem_ground = trunc_ground def extract_ground(self, g): f = self fc = f.content() gc = g.content() gcd = f.ring.domain.gcd(fc, gc) f = f.quo_ground(gcd) g = g.quo_ground(gcd) return gcd, f, g def _norm(f, norm_func): if not f: return f.ring.domain.zero else: ground_abs = f.ring.domain.abs return norm_func([ ground_abs(coeff) for coeff in f.itercoeffs() ]) def max_norm(f): return f._norm(max) def l1_norm(f): return f._norm(sum) def deflate(f, G): ring = f.ring polys = [f] + list(G) J = [0]ring.ngens for p in polys: for monom in p.itermonoms(): for i, m in enumerate(monom): J[i] = igcd(J[i], m) for i, b in enumerate(J): if not b: J[i] = 1 J = tuple(J) if all(b == 1 for b in J): return J, polys H = [] for p in polys: h = ring.zero for I, coeff in p.iterterms(): N = [ i // j for i, j in zip(I, J) ] h[tuple(N)] = coeff H.append(h) return J, H def inflate(f, J): poly = f.ring.zero for I, coeff in f.iterterms(): N = [ ij for i, j in zip(I, J) ] poly[tuple(N)] = coeff return poly def lcm(self, g): f = self domain = f.ring.domain if not domain.is_Field: fc, f = f.primitive() gc, g = g.primitive() c = domain.lcm(fc, gc) h = (fg).quo(f.gcd(g)) if not domain.is_Field: return h.mul_ground(c) else: return h.monic() def gcd(f, g): return f.cofactors(g)[0] def cofactors(f, g): if not f and not g: zero = f.ring.zero return zero, zero, zero elif not f: h, cff, cfg = f._gcd_zero(g) return h, cff, cfg elif not g: h, cfg, cff = g._gcd_zero(f) return h, cff, cfg elif len(f) == 1: h, cff, cfg = f._gcd_monom(g) return h, cff, cfg elif len(g) == 1: h, cfg, cff = g._gcd_monom(f) return h, cff, cfg J, (f, g) = f.deflate(g) h, cff, cfg = f._gcd(g) return (h.inflate(J), cff.inflate(J), cfg.inflate(J)) def _gcd_zero(f, g): one, zero = f.ring.one, f.ring.zero if g.is_nonnegative: return g, zero, one else: return -g, zero, -one def _gcd_monom(f, g): ring = f.ring ground_gcd = ring.domain.gcd ground_quo = ring.domain.quo monomial_gcd = ring.monomial_gcd monomial_ldiv = ring.monomial_ldiv mf, cf = list(f.iterterms())[0] _mgcd, _cgcd = mf, cf for mg, cg in g.iterterms(): _mgcd = monomial_gcd(_mgcd, mg) _cgcd = ground_gcd(_cgcd, cg) h = f.new([(_mgcd, _cgcd)]) cff = f.new([(monomial_ldiv(mf, _mgcd), ground_quo(cf, _cgcd))]) cfg = f.new([(monomial_ldiv(mg, _mgcd), ground_quo(cg, _cgcd)) for mg, cg in g.iterterms()]) return h, cff, cfg def _gcd(f, g): ring = f.ring if ring.domain.is_QQ: return f._gcd_QQ(g) elif ring.domain.is_ZZ: return f._gcd_ZZ(g) else: # TODO: don't use dense representation (port PRS algorithms) return ring.dmp_inner_gcd(f, g) def _gcd_ZZ(f, g): return heugcd(f, g) def _gcd_QQ(self, g): f = self ring = f.ring new_ring = ring.clone(domain=ring.domain.get_ring()) cf, f = f.clear_denoms() cg, g = g.clear_denoms() f = f.set_ring(new_ring) g = g.set_ring(new_ring) h, cff, cfg = f._gcd_ZZ(g) h = h.set_ring(ring) c, h = h.LC, h.monic() cff = cff.set_ring(ring).mul_ground(ring.domain.quo(c, cf)) cfg = cfg.set_ring(ring).mul_ground(ring.domain.quo(c, cg)) return h, cff, cfg def cancel(self, g): """ Cancel common factors in a rational function ``f/g``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> (2x2 - 2).cancel(x2 - 2x + 1) (2x + 2, x - 1) """ f = self ring = f.ring if not f: return f, ring.one domain = ring.domain if not (domain.is_Field and domain.has_assoc_Ring): _, p, q = f.cofactors(g) if q.is_negative: p, q = -p, -q else: new_ring = ring.clone(domain=domain.get_ring()) cq, f = f.clear_denoms() cp, g = g.clear_denoms() f = f.set_ring(new_ring) g = g.set_ring(new_ring) _, p, q = f.cofactors(g) _, cp, cq = new_ring.domain.cofactors(cp, cq) p = p.set_ring(ring) q = q.set_ring(ring) p_neg = p.is_negative q_neg = q.is_negative if p_neg and q_neg: p, q = -p, -q elif p_neg: cp, p = -cp, -p elif q_neg: cp, q = -cp, -q p = p.mul_ground(cp) q = q.mul_ground(cq) return p, q def diff(f, x): """Computes partial derivative in ``x``. Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> _, x, y = ring("x,y", ZZ) >>> p = x + x2y*3 >>> p.diff(x) 2xy3 + 1 """ ring = f.ring i = ring.index(x) m = ring.monomial_basis(i) g = ring.zero for expv, coeff in f.iterterms(): if expv[i]: e = ring.monomial_ldiv(expv, m) g[e] = ring.domain_new(coeffexpv[i]) return g def __call__(f, values): if 0 < len(values) <= f.ring.ngens: return f.evaluate(list(zip(f.ring.gens, values))) else: raise ValueError("expected at least 1 and at most %s values, got %s" % (f.ring.ngens, len(values))) def evaluate(self, x, a=None): f = self if isinstance(x, list) and a is None: (X, a), x = x[0], x[1:] f = f.evaluate(X, a) if not x: return f else: x = [ (Y.drop(X), a) for (Y, a) in x ] return f.evaluate(x) ring = f.ring i = ring.index(x) a = ring.domain.convert(a) if ring.ngens == 1: result = ring.domain.zero for (n,), coeff in f.iterterms(): result += coeffa*n return result else: poly = ring.drop(x).zero for monom, coeff in f.iterterms(): n, monom = monom[i], monom[:i] + monom[i+1:] coeff = coeffa*n if monom in poly: coeff = coeff + poly[monom] if coeff: poly[monom] = coeff else: del poly[monom] else: if coeff: poly[monom] = coeff return poly def subs(self, x, a=None): f = self if isinstance(x, list) and a is None: for X, a in x: f = f.subs(X, a) return f ring = f.ring i = ring.index(x) a = ring.domain.convert(a) if ring.ngens == 1: result = ring.domain.zero for (n,), coeff in f.iterterms(): result += coeffa*n return ring.ground_new(result) else: poly = ring.zero for monom, coeff in f.iterterms(): n, monom = monom[i], monom[:i] + (0,) + monom[i+1:] coeff = coeffa*n if monom in poly: coeff = coeff + poly[monom] if coeff: poly[monom] = coeff else: del poly[monom] else: if coeff: poly[monom] = coeff return poly def compose(f, x, a=None): ring = f.ring poly = ring.zero gens_map = dict(list(zip(ring.gens, list(range(ring.ngens))))) if a is not None: replacements = [(x, a)] else: if isinstance(x, list): replacements = list(x) elif isinstance(x, dict): replacements = sorted(list(x.items()), key=lambda k: gens_map[k[0]]) else: raise ValueError("expected a generator, value pair a sequence of such pairs") for k, (x, g) in enumerate(replacements): replacements[k] = (gens_map[x], ring.ring_new(g)) for monom, coeff in f.iterterms(): monom = list(monom) subpoly = ring.one for i, g in replacements: n, monom[i] = monom[i], 0 if n: subpoly = g**n subpoly = subpoly.mul_term((tuple(monom), coeff)) poly += subpoly return poly # TODO: following methods should point to polynomial # representation independent algorithm implementations. def pdiv(f, g): return f.ring.dmp_pdiv(f, g) def prem(f, g): return f.ring.dmp_prem(f, g) def pquo(f, g): return f.ring.dmp_quo(f, g) def pexquo(f, g): return f.ring.dmp_exquo(f, g) def half_gcdex(f, g): return f.ring.dmp_half_gcdex(f, g) def gcdex(f, g): return f.ring.dmp_gcdex(f, g) def subresultants(f, g): return f.ring.dmp_subresultants(f, g) def resultant(f, g): return f.ring.dmp_resultant(f, g) def discriminant(f): return f.ring.dmp_discriminant(f) def decompose(f): if f.ring.is_univariate: return f.ring.dup_decompose(f) else: raise MultivariatePolynomialError("polynomial decomposition") def shift(f, a): if f.ring.is_univariate: return f.ring.dup_shift(f, a) else: raise MultivariatePolynomialError("polynomial shift") def sturm(f): if f.ring.is_univariate: return f.ring.dup_sturm(f) else: raise MultivariatePolynomialError("sturm sequence") def gff_list(f): return f.ring.dmp_gff_list(f) def sqf_norm(f): return f.ring.dmp_sqf_norm(f) def sqf_part(f): return f.ring.dmp_sqf_part(f) def sqf_list(f, all=False): return f.ring.dmp_sqf_list(f, all=all) def factor_list(f): return f.ring.dmp_factor_list(f)
befa609b3b9e212879e14202cdcba1299674312e31f63263d318e1eaf399663b	"""Options manager for :class:`Poly` and public API functions. """ from __future__ import print_function, division __all__ = ["Options"] from sympy.core import S, Basic, sympify from sympy.core.compatibility import string_types, with_metaclass from sympy.polys.polyerrors import GeneratorsError, OptionError, FlagError from sympy.utilities import numbered_symbols, topological_sort, public from sympy.utilities.iterables import has_dups import sympy.polys import re class Option(object): """Base class for all kinds of options. """ option = None is_Flag = False requires = [] excludes = [] after = [] before = [] @classmethod def default(cls): return None @classmethod def preprocess(cls, option): return None @classmethod def postprocess(cls, options): pass class Flag(Option): """Base class for all kinds of flags. """ is_Flag = True class BooleanOption(Option): """An option that must have a boolean value or equivalent assigned. """ @classmethod def preprocess(cls, value): if value in [True, False]: return bool(value) else: raise OptionError("'%s' must have a boolean value assigned, got %s" % (cls.option, value)) class OptionType(type): """Base type for all options that does registers options. """ def __init__(cls, args, kwargs): @property def getter(self): try: return self[cls.option] except KeyError: return cls.default() setattr(Options, cls.option, getter) Options.__options__[cls.option] = cls @public class Options(dict): """ Options manager for polynomial manipulation module. Examples ======== >>> from sympy.polys.polyoptions import Options >>> from sympy.polys.polyoptions import build_options >>> from sympy.abc import x, y, z >>> Options((x, y, z), {'domain': 'ZZ'}) {'auto': False, 'domain': ZZ, 'gens': (x, y, z)} >>> build_options((x, y, z), {'domain': 'ZZ'}) {'auto': False, 'domain': ZZ, 'gens': (x, y, z)} Options* * Expand --- boolean option * Gens --- option * Wrt --- option * Sort --- option * Order --- option * Field --- boolean option * Greedy --- boolean option * Domain --- option * Split --- boolean option * Gaussian --- boolean option * Extension --- option * Modulus --- option * Symmetric --- boolean option * Strict --- boolean option Flags * Auto --- boolean flag * Frac --- boolean flag * Formal --- boolean flag * Polys --- boolean flag * Include --- boolean flag * All --- boolean flag * Gen --- flag * Series --- boolean flag """ __order__ = None __options__ = {} def __init__(self, gens, args, flags=None, strict=False): dict.__init__(self) if gens and args.get('gens', ()): raise OptionError( "both 'gens' and keyword argument 'gens' supplied") elif gens: args = dict(args) args['gens'] = gens defaults = args.pop('defaults', {}) def preprocess_options(args): for option, value in args.items(): try: cls = self.__options__[option] except KeyError: raise OptionError("'%s' is not a valid option" % option) if issubclass(cls, Flag): if flags is None or option not in flags: if strict: raise OptionError("'%s' flag is not allowed in this context" % option) if value is not None: self[option] = cls.preprocess(value) preprocess_options(args) for key, value in dict(defaults).items(): if key in self: del defaults[key] else: for option in self.keys(): cls = self.__options__[option] if key in cls.excludes: del defaults[key] break preprocess_options(defaults) for option in self.keys(): cls = self.__options__[option] for require_option in cls.requires: if self.get(require_option) is None: raise OptionError("'%s' option is only allowed together with '%s'" % (option, require_option)) for exclude_option in cls.excludes: if self.get(exclude_option) is not None: raise OptionError("'%s' option is not allowed together with '%s'" % (option, exclude_option)) for option in self.__order__: self.__options__[option].postprocess(self) @classmethod def _init_dependencies_order(cls): """Resolve the order of options' processing. """ if cls.__order__ is None: vertices, edges = [], set([]) for name, option in cls.__options__.items(): vertices.append(name) for _name in option.after: edges.add((_name, name)) for _name in option.before: edges.add((name, _name)) try: cls.__order__ = topological_sort((vertices, list(edges))) except ValueError: raise RuntimeError( "cycle detected in sympy.polys options framework") def clone(self, updates={}): """Clone ``self`` and update specified options. """ obj = dict.__new__(self.__class__) for option, value in self.items(): obj[option] = value for option, value in updates.items(): obj[option] = value return obj def __setattr__(self, attr, value): if attr in self.__options__: self[attr] = value else: super(Options, self).__setattr__(attr, value) @property def args(self): args = {} for option, value in self.items(): if value is not None and option != 'gens': cls = self.__options__[option] if not issubclass(cls, Flag): args[option] = value return args @property def options(self): options = {} for option, cls in self.__options__.items(): if not issubclass(cls, Flag): options[option] = getattr(self, option) return options @property def flags(self): flags = {} for option, cls in self.__options__.items(): if issubclass(cls, Flag): flags[option] = getattr(self, option) return flags class Expand(with_metaclass(OptionType, BooleanOption)): """``expand`` option to polynomial manipulation functions. """ option = 'expand' requires = [] excludes = [] @classmethod def default(cls): return True class Gens(with_metaclass(OptionType, Option)): """``gens`` option to polynomial manipulation functions. """ option = 'gens' requires = [] excludes = [] @classmethod def default(cls): return () @classmethod def preprocess(cls, gens): if isinstance(gens, Basic): gens = (gens,) elif len(gens) == 1 and hasattr(gens[0], '__iter__'): gens = gens[0] if gens == (None,): gens = () elif has_dups(gens): raise GeneratorsError("duplicated generators: %s" % str(gens)) elif any(gen.is_commutative is False for gen in gens): raise GeneratorsError("non-commutative generators: %s" % str(gens)) return tuple(gens) class Wrt(with_metaclass(OptionType, Option)): """``wrt`` option to polynomial manipulation functions. """ option = 'wrt' requires = [] excludes = [] _re_split = re.compile(r"\s,\s\|\s+") @classmethod def preprocess(cls, wrt): if isinstance(wrt, Basic): return [str(wrt)] elif isinstance(wrt, str): wrt = wrt.strip() if wrt.endswith(','): raise OptionError('Bad input: missing parameter.') if not wrt: return [] return [ gen for gen in cls._re_split.split(wrt) ] elif hasattr(wrt, '__getitem__'): return list(map(str, wrt)) else: raise OptionError("invalid argument for 'wrt' option") class Sort(with_metaclass(OptionType, Option)): """``sort`` option to polynomial manipulation functions. """ option = 'sort' requires = [] excludes = [] @classmethod def default(cls): return [] @classmethod def preprocess(cls, sort): if isinstance(sort, str): return [ gen.strip() for gen in sort.split('>') ] elif hasattr(sort, '__getitem__'): return list(map(str, sort)) else: raise OptionError("invalid argument for 'sort' option") class Order(with_metaclass(OptionType, Option)): """``order`` option to polynomial manipulation functions. """ option = 'order' requires = [] excludes = [] @classmethod def default(cls): return sympy.polys.orderings.lex @classmethod def preprocess(cls, order): return sympy.polys.orderings.monomial_key(order) class Field(with_metaclass(OptionType, BooleanOption)): """``field`` option to polynomial manipulation functions. """ option = 'field' requires = [] excludes = ['domain', 'split', 'gaussian'] class Greedy(with_metaclass(OptionType, BooleanOption)): """``greedy`` option to polynomial manipulation functions. """ option = 'greedy' requires = [] excludes = ['domain', 'split', 'gaussian', 'extension', 'modulus', 'symmetric'] class Composite(with_metaclass(OptionType, BooleanOption)): """``composite`` option to polynomial manipulation functions. """ option = 'composite' @classmethod def default(cls): return None requires = [] excludes = ['domain', 'split', 'gaussian', 'extension', 'modulus', 'symmetric'] class Domain(with_metaclass(OptionType, Option)): """``domain`` option to polynomial manipulation functions. """ option = 'domain' requires = [] excludes = ['field', 'greedy', 'split', 'gaussian', 'extension'] after = ['gens'] _re_realfield = re.compile(r"^(R\|RR)(_(\d+))?$") _re_complexfield = re.compile(r"^(C\|CC)(_(\d+))?$") _re_finitefield = re.compile(r"^(FF\|GF)\((\d+)\)$") _re_polynomial = re.compile(r"^(Z\|ZZ\|Q\|QQ)\[(.+)\]$") _re_fraction = re.compile(r"^(Z\|ZZ\|Q\|QQ)\((.+)\)$") _re_algebraic = re.compile(r"^(Q\|QQ)\<(.+)\>$") @classmethod def preprocess(cls, domain): if isinstance(domain, sympy.polys.domains.Domain): return domain elif hasattr(domain, 'to_domain'): return domain.to_domain() elif isinstance(domain, string_types): if domain in ['Z', 'ZZ']: return sympy.polys.domains.ZZ if domain in ['Q', 'QQ']: return sympy.polys.domains.QQ if domain == 'EX': return sympy.polys.domains.EX r = cls._re_realfield.match(domain) if r is not None: _, _, prec = r.groups() if prec is None: return sympy.polys.domains.RR else: return sympy.polys.domains.RealField(int(prec)) r = cls._re_complexfield.match(domain) if r is not None: _, _, prec = r.groups() if prec is None: return sympy.polys.domains.CC else: return sympy.polys.domains.ComplexField(int(prec)) r = cls._re_finitefield.match(domain) if r is not None: return sympy.polys.domains.FF(int(r.groups()[1])) r = cls._re_polynomial.match(domain) if r is not None: ground, gens = r.groups() gens = list(map(sympify, gens.split(','))) if ground in ['Z', 'ZZ']: return sympy.polys.domains.ZZ.poly_ring(gens) else: return sympy.polys.domains.QQ.poly_ring(gens) r = cls._re_fraction.match(domain) if r is not None: ground, gens = r.groups() gens = list(map(sympify, gens.split(','))) if ground in ['Z', 'ZZ']: return sympy.polys.domains.ZZ.frac_field(gens) else: return sympy.polys.domains.QQ.frac_field(gens) r = cls._re_algebraic.match(domain) if r is not None: gens = list(map(sympify, r.groups()[1].split(','))) return sympy.polys.domains.QQ.algebraic_field(gens) raise OptionError('expected a valid domain specification, got %s' % domain) @classmethod def postprocess(cls, options): if 'gens' in options and 'domain' in options and options['domain'].is_Composite and \ (set(options['domain'].symbols) & set(options['gens'])): raise GeneratorsError( "ground domain and generators interfere together") elif ('gens' not in options or not options['gens']) and \ 'domain' in options and options['domain'] == sympy.polys.domains.EX: raise GeneratorsError("you have to provide generators because EX domain was requested") class Split(with_metaclass(OptionType, BooleanOption)): """``split`` option to polynomial manipulation functions. """ option = 'split' requires = [] excludes = ['field', 'greedy', 'domain', 'gaussian', 'extension', 'modulus', 'symmetric'] @classmethod def postprocess(cls, options): if 'split' in options: raise NotImplementedError("'split' option is not implemented yet") class Gaussian(with_metaclass(OptionType, BooleanOption)): """``gaussian`` option to polynomial manipulation functions. """ option = 'gaussian' requires = [] excludes = ['field', 'greedy', 'domain', 'split', 'extension', 'modulus', 'symmetric'] @classmethod def postprocess(cls, options): if 'gaussian' in options and options['gaussian'] is True: options['extension'] = set([S.ImaginaryUnit]) Extension.postprocess(options) class Extension(with_metaclass(OptionType, Option)): """``extension`` option to polynomial manipulation functions. """ option = 'extension' requires = [] excludes = ['greedy', 'domain', 'split', 'gaussian', 'modulus', 'symmetric'] @classmethod def preprocess(cls, extension): if extension == 1: return bool(extension) elif extension == 0: raise OptionError("'False' is an invalid argument for 'extension'") else: if not hasattr(extension, '__iter__'): extension = set([extension]) else: if not extension: extension = None else: extension = set(extension) return extension @classmethod def postprocess(cls, options): if 'extension' in options and options['extension'] is not True: options['domain'] = sympy.polys.domains.QQ.algebraic_field( options['extension']) class Modulus(with_metaclass(OptionType, Option)): """``modulus`` option to polynomial manipulation functions. """ option = 'modulus' requires = [] excludes = ['greedy', 'split', 'domain', 'gaussian', 'extension'] @classmethod def preprocess(cls, modulus): modulus = sympify(modulus) if modulus.is_Integer and modulus > 0: return int(modulus) else: raise OptionError( "'modulus' must a positive integer, got %s" % modulus) @classmethod def postprocess(cls, options): if 'modulus' in options: modulus = options['modulus'] symmetric = options.get('symmetric', True) options['domain'] = sympy.polys.domains.FF(modulus, symmetric) class Symmetric(with_metaclass(OptionType, BooleanOption)): """``symmetric`` option to polynomial manipulation functions. """ option = 'symmetric' requires = ['modulus'] excludes = ['greedy', 'domain', 'split', 'gaussian', 'extension'] class Strict(with_metaclass(OptionType, BooleanOption)): """``strict`` option to polynomial manipulation functions. """ option = 'strict' @classmethod def default(cls): return True class Auto(with_metaclass(OptionType, BooleanOption, Flag)): """``auto`` flag to polynomial manipulation functions. """ option = 'auto' after = ['field', 'domain', 'extension', 'gaussian'] @classmethod def default(cls): return True @classmethod def postprocess(cls, options): if ('domain' in options or 'field' in options) and 'auto' not in options: options['auto'] = False class Frac(with_metaclass(OptionType, BooleanOption, Flag)): """``auto`` option to polynomial manipulation functions. """ option = 'frac' @classmethod def default(cls): return False class Formal(with_metaclass(OptionType, BooleanOption, Flag)): """``formal`` flag to polynomial manipulation functions. """ option = 'formal' @classmethod def default(cls): return False class Polys(with_metaclass(OptionType, BooleanOption, Flag)): """``polys`` flag to polynomial manipulation functions. """ option = 'polys' class Include(with_metaclass(OptionType, BooleanOption, Flag)): """``include`` flag to polynomial manipulation functions. """ option = 'include' @classmethod def default(cls): return False class All(with_metaclass(OptionType, BooleanOption, Flag)): """``all`` flag to polynomial manipulation functions. """ option = 'all' @classmethod def default(cls): return False class Gen(with_metaclass(OptionType, Flag)): """``gen`` flag to polynomial manipulation functions. """ option = 'gen' @classmethod def default(cls): return 0 @classmethod def preprocess(cls, gen): if isinstance(gen, (Basic, int)): return gen else: raise OptionError("invalid argument for 'gen' option") class Series(with_metaclass(OptionType, BooleanOption, Flag)): """``series`` flag to polynomial manipulation functions. """ option = 'series' @classmethod def default(cls): return False class Symbols(with_metaclass(OptionType, Flag)): """``symbols`` flag to polynomial manipulation functions. """ option = 'symbols' @classmethod def default(cls): return numbered_symbols('s', start=1) @classmethod def preprocess(cls, symbols): if hasattr(symbols, '__iter__'): return iter(symbols) else: raise OptionError("expected an iterator or iterable container, got %s" % symbols) class Method(with_metaclass(OptionType, Flag)): """``method`` flag to polynomial manipulation functions. """ option = 'method' @classmethod def preprocess(cls, method): if isinstance(method, str): return method.lower() else: raise OptionError("expected a string, got %s" % method) def build_options(gens, args=None): """Construct options from keyword arguments or ... options. """ if args is None: gens, args = (), gens if len(args) != 1 or 'opt' not in args or gens: return Options(gens, args) else: return args['opt'] def allowed_flags(args, flags): """ Allow specified flags to be used in the given context. Examples ======== >>> from sympy.polys.polyoptions import allowed_flags >>> from sympy.polys.domains import ZZ >>> allowed_flags({'domain': ZZ}, []) >>> allowed_flags({'domain': ZZ, 'frac': True}, []) Traceback (most recent call last): ... FlagError: 'frac' flag is not allowed in this context >>> allowed_flags({'domain': ZZ, 'frac': True}, ['frac']) """ flags = set(flags) for arg in args.keys(): try: if Options.__options__[arg].is_Flag and not arg in flags: raise FlagError( "'%s' flag is not allowed in this context" % arg) except KeyError: raise OptionError("'%s' is not a valid option" % arg) def set_defaults(options, *defaults): """Update options with default values. """ if 'defaults' not in options: options = dict(options) options['defaults'] = defaults return options Options._init_dependencies_order()
688445860665561413932e4b203a6bd9a27d4df06d8c7cfcb31205656a0427f1	"""Groebner bases algorithms. """ from __future__ import print_function, division from sympy.core.compatibility import range from sympy.core.symbol import Dummy from sympy.polys.monomials import monomial_mul, monomial_lcm, monomial_divides, term_div from sympy.polys.orderings import lex from sympy.polys.polyerrors import DomainError from sympy.polys.polyconfig import query def groebner(seq, ring, method=None): """ Computes Groebner basis for a set of polynomials in `K[X]`. Wrapper around the (default) improved Buchberger and the other algorithms for computing Groebner bases. The choice of algorithm can be changed via ``method`` argument or :func:`setup` from :mod:`sympy.polys.polyconfig`, where ``method`` can be either ``buchberger`` or ``f5b``. """ if method is None: method = query('groebner') _groebner_methods = { 'buchberger': _buchberger, 'f5b': _f5b, } try: _groebner = _groebner_methods[method] except KeyError: raise ValueError("'%s' is not a valid Groebner bases algorithm (valid are 'buchberger' and 'f5b')" % method) domain, orig = ring.domain, None if not domain.is_Field or not domain.has_assoc_Field: try: orig, ring = ring, ring.clone(domain=domain.get_field()) except DomainError: raise DomainError("can't compute a Groebner basis over %s" % domain) else: seq = [ s.set_ring(ring) for s in seq ] G = _groebner(seq, ring) if orig is not None: G = [ g.clear_denoms()[1].set_ring(orig) for g in G ] return G def _buchberger(f, ring): """ Computes Groebner basis for a set of polynomials in `K[X]`. Given a set of multivariate polynomials `F`, finds another set `G`, such that Ideal `F = Ideal G` and `G` is a reduced Groebner basis. The resulting basis is unique and has monic generators if the ground domains is a field. Otherwise the result is non-unique but Groebner bases over e.g. integers can be computed (if the input polynomials are monic). Groebner bases can be used to choose specific generators for a polynomial ideal. Because these bases are unique you can check for ideal equality by comparing the Groebner bases. To see if one polynomial lies in an ideal, divide by the elements in the base and see if the remainder vanishes. They can also be used to solve systems of polynomial equations as, by choosing lexicographic ordering, you can eliminate one variable at a time, provided that the ideal is zero-dimensional (finite number of solutions). Notes ===== Algorithm used: an improved version of Buchberger's algorithm as presented in T. Becker, V. Weispfenning, Groebner Bases: A Computational Approach to Commutative Algebra, Springer, 1993, page 232. References ========== .. [1] [Bose03]_ .. [2] [Giovini91]_ .. [3] [Ajwa95]_ .. [4] [Cox97]_ """ order = ring.order monomial_mul = ring.monomial_mul monomial_div = ring.monomial_div monomial_lcm = ring.monomial_lcm def select(P): # normal selection strategy # select the pair with minimum LCM(LM(f), LM(g)) pr = min(P, key=lambda pair: order(monomial_lcm(f[pair[0]].LM, f[pair[1]].LM))) return pr def normal(g, J): h = g.rem([ f[j] for j in J ]) if not h: return None else: h = h.monic() if not h in I: I[h] = len(f) f.append(h) return h.LM, I[h] def update(G, B, ih): # update G using the set of critical pairs B and h # [BW] page 230 h = f[ih] mh = h.LM # filter new pairs (h, g), g in G C = G.copy() D = set() while C: # select a pair (h, g) by popping an element from C ig = C.pop() g = f[ig] mg = g.LM LCMhg = monomial_lcm(mh, mg) def lcm_divides(ip): # LCM(LM(h), LM(p)) divides LCM(LM(h), LM(g)) m = monomial_lcm(mh, f[ip].LM) return monomial_div(LCMhg, m) # HT(h) and HT(g) disjoint: mhmg == LCMhg if monomial_mul(mh, mg) == LCMhg or ( not any(lcm_divides(ipx) for ipx in C) and not any(lcm_divides(pr[1]) for pr in D)): D.add((ih, ig)) E = set() while D: # select h, g from D (h the same as above) ih, ig = D.pop() mg = f[ig].LM LCMhg = monomial_lcm(mh, mg) if not monomial_mul(mh, mg) == LCMhg: E.add((ih, ig)) # filter old pairs B_new = set() while B: # select g1, g2 from B (-> CP) ig1, ig2 = B.pop() mg1 = f[ig1].LM mg2 = f[ig2].LM LCM12 = monomial_lcm(mg1, mg2) # if HT(h) does not divide lcm(HT(g1), HT(g2)) if not monomial_div(LCM12, mh) or \ monomial_lcm(mg1, mh) == LCM12 or \ monomial_lcm(mg2, mh) == LCM12: B_new.add((ig1, ig2)) B_new \|= E # filter polynomials G_new = set() while G: ig = G.pop() mg = f[ig].LM if not monomial_div(mg, mh): G_new.add(ig) G_new.add(ih) return G_new, B_new # end of update ################################ if not f: return [] # replace f with a reduced list of initial polynomials; see [BW] page 203 f1 = f[:] while True: f = f1[:] f1 = [] for i in range(len(f)): p = f[i] r = p.rem(f[:i]) if r: f1.append(r.monic()) if f == f1: break I = {} # ip = I[p]; p = f[ip] F = set() # set of indices of polynomials G = set() # set of indices of intermediate would-be Groebner basis CP = set() # set of pairs of indices of critical pairs for i, h in enumerate(f): I[h] = i F.add(i) ##################################### # algorithm GROEBNERNEWS2 in [BW] page 232 while F: # select p with minimum monomial according to the monomial ordering h = min([f[x] for x in F], key=lambda f: order(f.LM)) ih = I[h] F.remove(ih) G, CP = update(G, CP, ih) # count the number of critical pairs which reduce to zero reductions_to_zero = 0 while CP: ig1, ig2 = select(CP) CP.remove((ig1, ig2)) h = spoly(f[ig1], f[ig2], ring) # ordering divisors is on average more efficient [Cox] page 111 G1 = sorted(G, key=lambda g: order(f[g].LM)) ht = normal(h, G1) if ht: G, CP = update(G, CP, ht[1]) else: reductions_to_zero += 1 ###################################### # now G is a Groebner basis; reduce it Gr = set() for ig in G: ht = normal(f[ig], G - set([ig])) if ht: Gr.add(ht[1]) Gr = [f[ig] for ig in Gr] # order according to the monomial ordering Gr = sorted(Gr, key=lambda f: order(f.LM), reverse=True) return Gr def spoly(p1, p2, ring): """ Compute LCM(LM(p1), LM(p2))/LM(p1)p1 - LCM(LM(p1), LM(p2))/LM(p2)p2 This is the S-poly provided p1 and p2 are monic """ LM1 = p1.LM LM2 = p2.LM LCM12 = ring.monomial_lcm(LM1, LM2) m1 = ring.monomial_div(LCM12, LM1) m2 = ring.monomial_div(LCM12, LM2) s1 = p1.mul_monom(m1) s2 = p2.mul_monom(m2) s = s1 - s2 return s # F5B # convenience functions def Sign(f): return f[0] def Polyn(f): return f[1] def Num(f): return f[2] def sig(monomial, index): return (monomial, index) def lbp(signature, polynomial, number): return (signature, polynomial, number) # signature functions def sig_cmp(u, v, order): """ Compare two signatures by extending the term order to K[X]^n. u < v iff - the index of v is greater than the index of u or - the index of v is equal to the index of u and u[0] < v[0] w.r.t. order u > v otherwise """ if u[1] > v[1]: return -1 if u[1] == v[1]: #if u[0] == v[0]: # return 0 if order(u[0]) < order(v[0]): return -1 return 1 def sig_key(s, order): """ Key for comparing two signatures. s = (m, k), t = (n, l) s < t iff [k > l] or [k == l and m < n] s > t otherwise """ return (-s[1], order(s[0])) def sig_mult(s, m): """ Multiply a signature by a monomial. The product of a signature (m, i) and a monomial n is defined as (m t, i). """ return sig(monomial_mul(s[0], m), s[1]) # labeled polynomial functions def lbp_sub(f, g): """ Subtract labeled polynomial g from f. The signature and number of the difference of f and g are signature and number of the maximum of f and g, w.r.t. lbp_cmp. """ if sig_cmp(Sign(f), Sign(g), Polyn(f).ring.order) < 0: max_poly = g else: max_poly = f ret = Polyn(f) - Polyn(g) return lbp(Sign(max_poly), ret, Num(max_poly)) def lbp_mul_term(f, cx): """ Multiply a labeled polynomial with a term. The product of a labeled polynomial (s, p, k) by a monomial is defined as (m * s, m * p, k). """ return lbp(sig_mult(Sign(f), cx[0]), Polyn(f).mul_term(cx), Num(f)) def lbp_cmp(f, g): """ Compare two labeled polynomials. f < g iff - Sign(f) < Sign(g) or - Sign(f) == Sign(g) and Num(f) > Num(g) f > g otherwise """ if sig_cmp(Sign(f), Sign(g), Polyn(f).ring.order) == -1: return -1 if Sign(f) == Sign(g): if Num(f) > Num(g): return -1 #if Num(f) == Num(g): # return 0 return 1 def lbp_key(f): """ Key for comparing two labeled polynomials. """ return (sig_key(Sign(f), Polyn(f).ring.order), -Num(f)) # algorithm and helper functions def critical_pair(f, g, ring): """ Compute the critical pair corresponding to two labeled polynomials. A critical pair is a tuple (um, f, vm, g), where um and vm are terms such that um * f - vm * g is the S-polynomial of f and g (so, wlog assume um * f > vm * g). For performance sake, a critical pair is represented as a tuple (Sign(um * f), um, f, Sign(vm * g), vm, g), since um * f creates a new, relatively expensive object in memory, whereas Sign(um * f) and um are lightweight and f (in the tuple) is a reference to an already existing object in memory. """ domain = ring.domain ltf = Polyn(f).LT ltg = Polyn(g).LT lt = (monomial_lcm(ltf[0], ltg[0]), domain.one) um = term_div(lt, ltf, domain) vm = term_div(lt, ltg, domain) # The full information is not needed (now), so only the product # with the leading term is considered: fr = lbp_mul_term(lbp(Sign(f), Polyn(f).leading_term(), Num(f)), um) gr = lbp_mul_term(lbp(Sign(g), Polyn(g).leading_term(), Num(g)), vm) # return in proper order, such that the S-polynomial is just # u_first * f_first - u_second * f_second: if lbp_cmp(fr, gr) == -1: return (Sign(gr), vm, g, Sign(fr), um, f) else: return (Sign(fr), um, f, Sign(gr), vm, g) def cp_cmp(c, d): """ Compare two critical pairs c and d. c < d iff - lbp(c[0], _, Num(c[2]) < lbp(d[0], _, Num(d[2])) (this corresponds to um_c * f_c and um_d * f_d) or - lbp(c[0], _, Num(c[2]) >< lbp(d[0], _, Num(d[2])) and lbp(c[3], _, Num(c[5])) < lbp(d[3], _, Num(d[5])) (this corresponds to vm_c * g_c and vm_d * g_d) c > d otherwise """ zero = Polyn(c[2]).ring.zero c0 = lbp(c[0], zero, Num(c[2])) d0 = lbp(d[0], zero, Num(d[2])) r = lbp_cmp(c0, d0) if r == -1: return -1 if r == 0: c1 = lbp(c[3], zero, Num(c[5])) d1 = lbp(d[3], zero, Num(d[5])) r = lbp_cmp(c1, d1) if r == -1: return -1 #if r == 0: # return 0 return 1 def cp_key(c, ring): """ Key for comparing critical pairs. """ return (lbp_key(lbp(c[0], ring.zero, Num(c[2]))), lbp_key(lbp(c[3], ring.zero, Num(c[5])))) def s_poly(cp): """ Compute the S-polynomial of a critical pair. The S-polynomial of a critical pair cp is cp[1] * cp[2] - cp[4] * cp[5]. """ return lbp_sub(lbp_mul_term(cp[2], cp[1]), lbp_mul_term(cp[5], cp[4])) def is_rewritable_or_comparable(sign, num, B): """ Check if a labeled polynomial is redundant by checking if its signature and number imply rewritability or comparability. (sign, num) is comparable if there exists a labeled polynomial h in B, such that sign[1] (the index) is less than Sign(h)[1] and sign[0] is divisible by the leading monomial of h. (sign, num) is rewritable if there exists a labeled polynomial h in B, such thatsign[1] is equal to Sign(h)[1], num < Num(h) and sign[0] is divisible by Sign(h)[0]. """ for h in B: # comparable if sign[1] < Sign(h)[1]: if monomial_divides(Polyn(h).LM, sign[0]): return True # rewritable if sign[1] == Sign(h)[1]: if num < Num(h): if monomial_divides(Sign(h)[0], sign[0]): return True return False def f5_reduce(f, B): """ F5-reduce a labeled polynomial f by B. Continuously searches for non-zero labeled polynomial h in B, such that the leading term lt_h of h divides the leading term lt_f of f and Sign(lt_h * h) < Sign(f). If such a labeled polynomial h is found, f gets replaced by f - lt_f / lt_h * h. If no such h can be found or f is 0, f is no further F5-reducible and f gets returned. A polynomial that is reducible in the usual sense need not be F5-reducible, e.g.: >>> from sympy.polys.groebnertools import lbp, sig, f5_reduce, Polyn >>> from sympy.polys import ring, QQ, lex >>> R, x,y,z = ring("x,y,z", QQ, lex) >>> f = lbp(sig((1, 1, 1), 4), x, 3) >>> g = lbp(sig((0, 0, 0), 2), x, 2) >>> Polyn(f).rem([Polyn(g)]) 0 >>> f5_reduce(f, [g]) (((1, 1, 1), 4), x, 3) """ order = Polyn(f).ring.order domain = Polyn(f).ring.domain if not Polyn(f): return f while True: g = f for h in B: if Polyn(h): if monomial_divides(Polyn(h).LM, Polyn(f).LM): t = term_div(Polyn(f).LT, Polyn(h).LT, domain) if sig_cmp(sig_mult(Sign(h), t[0]), Sign(f), order) < 0: # The following check need not be done and is in general slower than without. #if not is_rewritable_or_comparable(Sign(gp), Num(gp), B): hp = lbp_mul_term(h, t) f = lbp_sub(f, hp) break if g == f or not Polyn(f): return f def _f5b(F, ring): """ Computes a reduced Groebner basis for the ideal generated by F. f5b is an implementation of the F5B algorithm by Yao Sun and Dingkang Wang. Similarly to Buchberger's algorithm, the algorithm proceeds by computing critical pairs, computing the S-polynomial, reducing it and adjoining the reduced S-polynomial if it is not 0. Unlike Buchberger's algorithm, each polynomial contains additional information, namely a signature and a number. The signature specifies the path of computation (i.e. from which polynomial in the original basis was it derived and how), the number says when the polynomial was added to the basis. With this information it is (often) possible to decide if an S-polynomial will reduce to 0 and can be discarded. Optimizations include: Reducing the generators before computing a Groebner basis, removing redundant critical pairs when a new polynomial enters the basis and sorting the critical pairs and the current basis. Once a Groebner basis has been found, it gets reduced. References ========== .. [1] Yao Sun, Dingkang Wang: "A New Proof for the Correctness of F5 (F5-Like) Algorithm", http://arxiv.org/abs/1004.0084 (specifically v4) .. [2] Thomas Becker, Volker Weispfenning, Groebner bases: A computational approach to commutative algebra, 1993, p. 203, 216 """ order = ring.order # reduce polynomials (like in Mario Pernici's implementation) (Becker, Weispfenning, p. 203) B = F while True: F = B B = [] for i in range(len(F)): p = F[i] r = p.rem(F[:i]) if r: B.append(r) if F == B: break # basis B = [lbp(sig(ring.zero_monom, i + 1), F[i], i + 1) for i in range(len(F))] B.sort(key=lambda f: order(Polyn(f).LM), reverse=True) # critical pairs CP = [critical_pair(B[i], B[j], ring) for i in range(len(B)) for j in range(i + 1, len(B))] CP.sort(key=lambda cp: cp_key(cp, ring), reverse=True) k = len(B) reductions_to_zero = 0 while len(CP): cp = CP.pop() # discard redundant critical pairs: if is_rewritable_or_comparable(cp[0], Num(cp[2]), B): continue if is_rewritable_or_comparable(cp[3], Num(cp[5]), B): continue s = s_poly(cp) p = f5_reduce(s, B) p = lbp(Sign(p), Polyn(p).monic(), k + 1) if Polyn(p): # remove old critical pairs, that become redundant when adding p: indices = [] for i, cp in enumerate(CP): if is_rewritable_or_comparable(cp[0], Num(cp[2]), [p]): indices.append(i) elif is_rewritable_or_comparable(cp[3], Num(cp[5]), [p]): indices.append(i) for i in reversed(indices): del CP[i] # only add new critical pairs that are not made redundant by p: for g in B: if Polyn(g): cp = critical_pair(p, g, ring) if is_rewritable_or_comparable(cp[0], Num(cp[2]), [p]): continue elif is_rewritable_or_comparable(cp[3], Num(cp[5]), [p]): continue CP.append(cp) # sort (other sorting methods/selection strategies were not as successful) CP.sort(key=lambda cp: cp_key(cp, ring), reverse=True) # insert p into B: m = Polyn(p).LM if order(m) <= order(Polyn(B[-1]).LM): B.append(p) else: for i, q in enumerate(B): if order(m) > order(Polyn(q).LM): B.insert(i, p) break k += 1 #print(len(B), len(CP), "%d critical pairs removed" % len(indices)) else: reductions_to_zero += 1 # reduce Groebner basis: H = [Polyn(g).monic() for g in B] H = red_groebner(H, ring) return sorted(H, key=lambda f: order(f.LM), reverse=True) def red_groebner(G, ring): """ Compute reduced Groebner basis, from BeckerWeispfenning93, p. 216 Selects a subset of generators, that already generate the ideal and computes a reduced Groebner basis for them. """ def reduction(P): """ The actual reduction algorithm. """ Q = [] for i, p in enumerate(P): h = p.rem(P[:i] + P[i + 1:]) if h: Q.append(h) return [p.monic() for p in Q] F = G H = [] while F: f0 = F.pop() if not any(monomial_divides(f.LM, f0.LM) for f in F + H): H.append(f0) # Becker, Weispfenning, p. 217: H is Groebner basis of the ideal generated by G. return reduction(H) def is_groebner(G, ring): """ Check if G is a Groebner basis. """ for i in range(len(G)): for j in range(i + 1, len(G)): s = spoly(G[i], G[j], ring) s = s.rem(G) if s: return False return True def is_minimal(G, ring): """ Checks if G is a minimal Groebner basis. """ order = ring.order domain = ring.domain G.sort(key=lambda g: order(g.LM)) for i, g in enumerate(G): if g.LC != domain.one: return False for h in G[:i] + G[i + 1:]: if monomial_divides(h.LM, g.LM): return False return True def is_reduced(G, ring): """ Checks if G is a reduced Groebner basis. """ order = ring.order domain = ring.domain G.sort(key=lambda g: order(g.LM)) for i, g in enumerate(G): if g.LC != domain.one: return False for term in g: for h in G[:i] + G[i + 1:]: if monomial_divides(h.LM, term[0]): return False return True def groebner_lcm(f, g): """ Computes LCM of two polynomials using Groebner bases. The LCM is computed as the unique generator of the intersection of the two ideals generated by `f` and `g`. The approach is to compute a Groebner basis with respect to lexicographic ordering of `tf` and `(1 - t)g`, where `t` is an unrelated variable and then filtering out the solution that doesn't contain `t`. References ========== .. [1] [Cox97]_ """ if f.ring != g.ring: raise ValueError("Values should be equal") ring = f.ring domain = ring.domain if not f or not g: return ring.zero if len(f) <= 1 and len(g) <= 1: monom = monomial_lcm(f.LM, g.LM) coeff = domain.lcm(f.LC, g.LC) return ring.term_new(monom, coeff) fc, f = f.primitive() gc, g = g.primitive() lcm = domain.lcm(fc, gc) f_terms = [ ((1,) + monom, coeff) for monom, coeff in f.terms() ] g_terms = [ ((0,) + monom, coeff) for monom, coeff in g.terms() ] \ + [ ((1,) + monom,-coeff) for monom, coeff in g.terms() ] t = Dummy("t") t_ring = ring.clone(symbols=(t,) + ring.symbols, order=lex) F = t_ring.from_terms(f_terms) G = t_ring.from_terms(g_terms) basis = groebner([F, G], t_ring) def is_independent(h, j): return all(not monom[j] for monom in h.monoms()) H = [ h for h in basis if is_independent(h, 0) ] h_terms = [ (monom[1:], coefflcm) for monom, coeff in H[0].terms() ] h = ring.from_terms(h_terms) return h def groebner_gcd(f, g): """Computes GCD of two polynomials using Groebner bases. """ if f.ring != g.ring: raise ValueError("Values should be equal") domain = f.ring.domain if not domain.is_Field: fc, f = f.primitive() gc, g = g.primitive() gcd = domain.gcd(fc, gc) H = (fg).quo([groebner_lcm(f, g)]) if len(H) != 1: raise ValueError("Length should be 1") h = H[0] if not domain.is_Field: return gcd*h else: return h.monic()
624776ff4341eff352b24bc0ebf8ddaf2e9ff0170adfe4e3b05fc4d77ad52c67	from sympy import Dummy from sympy.core.compatibility import range from sympy.ntheory import nextprime from sympy.ntheory.modular import crt from sympy.polys.domains import PolynomialRing from sympy.polys.galoistools import ( gf_gcd, gf_from_dict, gf_gcdex, gf_div, gf_lcm) from sympy.polys.polyerrors import ModularGCDFailed from mpmath import sqrt import random def _trivial_gcd(f, g): """ Compute the GCD of two polynomials in trivial cases, i.e. when one or both polynomials are zero. """ ring = f.ring if not (f or g): return ring.zero, ring.zero, ring.zero elif not f: if g.LC < ring.domain.zero: return -g, ring.zero, -ring.one else: return g, ring.zero, ring.one elif not g: if f.LC < ring.domain.zero: return -f, -ring.one, ring.zero else: return f, ring.one, ring.zero return None def _gf_gcd(fp, gp, p): r""" Compute the GCD of two univariate polynomials in `\mathbb{Z}_p[x]`. """ dom = fp.ring.domain while gp: rem = fp deg = gp.degree() lcinv = dom.invert(gp.LC, p) while True: degrem = rem.degree() if degrem < deg: break rem = (rem - gp.mul_monom((degrem - deg,)).mul_ground(lcinv * rem.LC)).trunc_ground(p) fp = gp gp = rem return fp.mul_ground(dom.invert(fp.LC, p)).trunc_ground(p) def _degree_bound_univariate(f, g): r""" Compute an upper bound for the degree of the GCD of two univariate integer polynomials `f` and `g`. The function chooses a suitable prime `p` and computes the GCD of `f` and `g` in `\mathbb{Z}_p[x]`. The choice of `p` guarantees that the degree in `\mathbb{Z}_p[x]` is greater than or equal to the degree in `\mathbb{Z}[x]`. Parameters ========== f : PolyElement univariate integer polynomial g : PolyElement univariate integer polynomial """ gamma = f.ring.domain.gcd(f.LC, g.LC) p = 1 p = nextprime(p) while gamma % p == 0: p = nextprime(p) fp = f.trunc_ground(p) gp = g.trunc_ground(p) hp = _gf_gcd(fp, gp, p) deghp = hp.degree() return deghp def _chinese_remainder_reconstruction_univariate(hp, hq, p, q): r""" Construct a polynomial `h_{pq}` in `\mathbb{Z}_{p q}[x]` such that .. math :: h_{pq} = h_p \; \mathrm{mod} \, p h_{pq} = h_q \; \mathrm{mod} \, q for relatively prime integers `p` and `q` and polynomials `h_p` and `h_q` in `\mathbb{Z}_p[x]` and `\mathbb{Z}_q[x]` respectively. The coefficients of the polynomial `h_{pq}` are computed with the Chinese Remainder Theorem. The symmetric representation in `\mathbb{Z}_p[x]`, `\mathbb{Z}_q[x]` and `\mathbb{Z}_{p q}[x]` is used. It is assumed that `h_p` and `h_q` have the same degree. Parameters ========== hp : PolyElement univariate integer polynomial with coefficients in `\mathbb{Z}_p` hq : PolyElement univariate integer polynomial with coefficients in `\mathbb{Z}_q` p : Integer modulus of `h_p`, relatively prime to `q` q : Integer modulus of `h_q`, relatively prime to `p` Examples ======== >>> from sympy.polys.modulargcd import _chinese_remainder_reconstruction_univariate >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> p = 3 >>> q = 5 >>> hp = -x*3 - 1 >>> hq = 2x*3 - 2x*2 + x >>> hpq = _chinese_remainder_reconstruction_univariate(hp, hq, p, q) >>> hpq 2x*3 + 3x*2 + 6x + 5 >>> hpq.trunc_ground(p) == hp True >>> hpq.trunc_ground(q) == hq True """ n = hp.degree() x = hp.ring.gens[0] hpq = hp.ring.zero for i in range(n+1): hpq[(i,)] = crt([p, q], [hp.coeff(xi), hq.coeff(xi)], symmetric=True)[0] hpq.strip_zero() return hpq def modgcd_univariate(f, g): r""" Computes the GCD of two polynomials in `\mathbb{Z}[x]` using a modular algorithm. The algorithm computes the GCD of two univariate integer polynomials `f` and `g` by computing the GCD in `\mathbb{Z}_p[x]` for suitable primes `p` and then reconstructing the coefficients with the Chinese Remainder Theorem. Trial division is only made for candidates which are very likely the desired GCD. Parameters ========== f : PolyElement univariate integer polynomial g : PolyElement univariate integer polynomial Returns ======= h : PolyElement GCD of the polynomials `f` and `g` cff : PolyElement cofactor of `f`, i.e. `\frac{f}{h}` cfg : PolyElement cofactor of `g`, i.e. `\frac{g}{h}` Examples ======== >>> from sympy.polys.modulargcd import modgcd_univariate >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> f = x5 - 1 >>> g = x - 1 >>> h, cff, cfg = modgcd_univariate(f, g) >>> h, cff, cfg (x - 1, x4 + x3 + x2 + x + 1, 1) >>> cff * h == f True >>> cfg * h == g True >>> f = 6x2 - 6 >>> g = 2x*2 + 4x + 2 >>> h, cff, cfg = modgcd_univariate(f, g) >>> h, cff, cfg (2x + 2, 3x - 3, x + 1) >>> cff * h == f True >>> cfg * h == g True References ========== 1. [Monagan00]_ """ assert f.ring == g.ring and f.ring.domain.is_ZZ result = _trivial_gcd(f, g) if result is not None: return result ring = f.ring cf, f = f.primitive() cg, g = g.primitive() ch = ring.domain.gcd(cf, cg) bound = _degree_bound_univariate(f, g) if bound == 0: return ring(ch), f.mul_ground(cf // ch), g.mul_ground(cg // ch) gamma = ring.domain.gcd(f.LC, g.LC) m = 1 p = 1 while True: p = nextprime(p) while gamma % p == 0: p = nextprime(p) fp = f.trunc_ground(p) gp = g.trunc_ground(p) hp = _gf_gcd(fp, gp, p) deghp = hp.degree() if deghp > bound: continue elif deghp < bound: m = 1 bound = deghp continue hp = hp.mul_ground(gamma).trunc_ground(p) if m == 1: m = p hlastm = hp continue hm = _chinese_remainder_reconstruction_univariate(hp, hlastm, p, m) m = p if not hm == hlastm: hlastm = hm continue h = hm.quo_ground(hm.content()) fquo, frem = f.div(h) gquo, grem = g.div(h) if not frem and not grem: if h.LC < 0: ch = -ch h = h.mul_ground(ch) cff = fquo.mul_ground(cf // ch) cfg = gquo.mul_ground(cg // ch) return h, cff, cfg def _primitive(f, p): r""" Compute the content and the primitive part of a polynomial in `\mathbb{Z}_p[x_0, \ldots, x_{k-2}, y] \cong \mathbb{Z}_p[y][x_0, \ldots, x_{k-2}]`. Parameters ========== f : PolyElement integer polynomial in `\mathbb{Z}_p[x0, \ldots, x{k-2}, y]` p : Integer modulus of `f` Returns ======= contf : PolyElement integer polynomial in `\mathbb{Z}_p[y]`, content of `f` ppf : PolyElement primitive part of `f`, i.e. `\frac{f}{contf}` Examples ======== >>> from sympy.polys.modulargcd import _primitive >>> from sympy.polys import ring, ZZ >>> R, x, y = ring("x, y", ZZ) >>> p = 3 >>> f = x2y2 + x2y - y2 - y >>> _primitive(f, p) (y2 + y, x2 - 1) >>> R, x, y, z = ring("x, y, z", ZZ) >>> f = xyz - y2z*2 >>> _primitive(f, p) (z, xy - y*2z) """ ring = f.ring dom = ring.domain k = ring.ngens coeffs = {} for monom, coeff in f.iterterms(): if monom[:-1] not in coeffs: coeffs[monom[:-1]] = {} coeffs[monom[:-1]][monom[-1]] = coeff cont = [] for coeff in iter(coeffs.values()): cont = gf_gcd(cont, gf_from_dict(coeff, p, dom), p, dom) yring = ring.clone(symbols=ring.symbols[k-1]) contf = yring.from_dense(cont).trunc_ground(p) return contf, f.quo(contf.set_ring(ring)) def _deg(f): r""" Compute the degree of a multivariate polynomial `f \in K[x_0, \ldots, x_{k-2}, y] \cong K[y][x_0, \ldots, x_{k-2}]`. Parameters ========== f : PolyElement polynomial in `K[x_0, \ldots, x_{k-2}, y]` Returns ======= degf : Integer tuple degree of `f` in `x_0, \ldots, x_{k-2}` Examples ======== >>> from sympy.polys.modulargcd import _deg >>> from sympy.polys import ring, ZZ >>> R, x, y = ring("x, y", ZZ) >>> f = x*2y2 + x2y - 1 >>> _deg(f) (2,) >>> R, x, y, z = ring("x, y, z", ZZ) >>> f = x2y2 + x2y - 1 >>> _deg(f) (2, 2) >>> f = xyz - y2z*2 >>> _deg(f) (1, 1) """ k = f.ring.ngens degf = (0,) (k-1) for monom in f.itermonoms(): if monom[:-1] > degf: degf = monom[:-1] return degf def _LC(f): r""" Compute the leading coefficient of a multivariate polynomial `f \in K[x_0, \ldots, x_{k-2}, y] \cong K[y][x_0, \ldots, x_{k-2}]`. Parameters ========== f : PolyElement polynomial in `K[x_0, \ldots, x_{k-2}, y]` Returns ======= lcf : PolyElement polynomial in `K[y]`, leading coefficient of `f` Examples ======== >>> from sympy.polys.modulargcd import _LC >>> from sympy.polys import ring, ZZ >>> R, x, y = ring("x, y", ZZ) >>> f = x*2y2 + x2y - 1 >>> _LC(f) y2 + y >>> R, x, y, z = ring("x, y, z", ZZ) >>> f = x2y2 + x2y - 1 >>> _LC(f) 1 >>> f = xyz - y2z*2 >>> _LC(f) z """ ring = f.ring k = ring.ngens yring = ring.clone(symbols=ring.symbols[k-1]) y = yring.gens[0] degf = _deg(f) lcf = yring.zero for monom, coeff in f.iterterms(): if monom[:-1] == degf: lcf += coeffy*monom[-1] return lcf def _swap(f, i): """ Make the variable `x_i` the leading one in a multivariate polynomial `f`. """ ring = f.ring fswap = ring.zero for monom, coeff in f.iterterms(): monomswap = (monom[i],) + monom[:i] + monom[i+1:] fswap[monomswap] = coeff return fswap def _degree_bound_bivariate(f, g): r""" Compute upper degree bounds for the GCD of two bivariate integer polynomials `f` and `g`. The GCD is viewed as a polynomial in `\mathbb{Z}[y][x]` and the function returns an upper bound for its degree and one for the degree of its content. This is done by choosing a suitable prime `p` and computing the GCD of the contents of `f \; \mathrm{mod} \, p` and `g \; \mathrm{mod} \, p`. The choice of `p` guarantees that the degree of the content in `\mathbb{Z}_p[y]` is greater than or equal to the degree in `\mathbb{Z}[y]`. To obtain the degree bound in the variable `x`, the polynomials are evaluated at `y = a` for a suitable `a \in \mathbb{Z}_p` and then their GCD in `\mathbb{Z}_p[x]` is computed. If no such `a` exists, i.e. the degree in `\mathbb{Z}_p[x]` is always smaller than the one in `\mathbb{Z}[y][x]`, then the bound is set to the minimum of the degrees of `f` and `g` in `x`. Parameters ========== f : PolyElement bivariate integer polynomial g : PolyElement bivariate integer polynomial Returns ======= xbound : Integer upper bound for the degree of the GCD of the polynomials `f` and `g` in the variable `x` ycontbound : Integer upper bound for the degree of the content of the GCD of the polynomials `f` and `g` in the variable `y` References ========== 1. [Monagan00]_ """ ring = f.ring gamma1 = ring.domain.gcd(f.LC, g.LC) gamma2 = ring.domain.gcd(_swap(f, 1).LC, _swap(g, 1).LC) badprimes = gamma1 gamma2 p = 1 p = nextprime(p) while badprimes % p == 0: p = nextprime(p) fp = f.trunc_ground(p) gp = g.trunc_ground(p) contfp, fp = _primitive(fp, p) contgp, gp = _primitive(gp, p) conthp = _gf_gcd(contfp, contgp, p) # polynomial in Z_p[y] ycontbound = conthp.degree() # polynomial in Z_p[y] delta = _gf_gcd(_LC(fp), _LC(gp), p) for a in range(p): if not delta.evaluate(0, a) % p: continue fpa = fp.evaluate(1, a).trunc_ground(p) gpa = gp.evaluate(1, a).trunc_ground(p) hpa = _gf_gcd(fpa, gpa, p) xbound = hpa.degree() return xbound, ycontbound return min(fp.degree(), gp.degree()), ycontbound def _chinese_remainder_reconstruction_multivariate(hp, hq, p, q): r""" Construct a polynomial `h_{pq}` in `\mathbb{Z}_{p q}[x_0, \ldots, x_{k-1}]` such that .. math :: h_{pq} = h_p \; \mathrm{mod} \, p h_{pq} = h_q \; \mathrm{mod} \, q for relatively prime integers `p` and `q` and polynomials `h_p` and `h_q` in `\mathbb{Z}_p[x_0, \ldots, x_{k-1}]` and `\mathbb{Z}_q[x_0, \ldots, x_{k-1}]` respectively. The coefficients of the polynomial `h_{pq}` are computed with the Chinese Remainder Theorem. The symmetric representation in `\mathbb{Z}_p[x_0, \ldots, x_{k-1}]`, `\mathbb{Z}_q[x_0, \ldots, x_{k-1}]` and `\mathbb{Z}_{p q}[x_0, \ldots, x_{k-1}]` is used. Parameters ========== hp : PolyElement multivariate integer polynomial with coefficients in `\mathbb{Z}_p` hq : PolyElement multivariate integer polynomial with coefficients in `\mathbb{Z}_q` p : Integer modulus of `h_p`, relatively prime to `q` q : Integer modulus of `h_q`, relatively prime to `p` Examples ======== >>> from sympy.polys.modulargcd import _chinese_remainder_reconstruction_multivariate >>> from sympy.polys import ring, ZZ >>> R, x, y = ring("x, y", ZZ) >>> p = 3 >>> q = 5 >>> hp = x*3y - x2 - 1 >>> hq = -x3y - 2xy2 + 2 >>> hpq = _chinese_remainder_reconstruction_multivariate(hp, hq, p, q) >>> hpq 4x*3y + 5x2 + 3xy2 + 2 >>> hpq.trunc_ground(p) == hp True >>> hpq.trunc_ground(q) == hq True >>> R, x, y, z = ring("x, y, z", ZZ) >>> p = 6 >>> q = 5 >>> hp = 3x4 - y3z + z >>> hq = -2x*4 + z >>> hpq = _chinese_remainder_reconstruction_multivariate(hp, hq, p, q) >>> hpq 3x*4 + 5y*3z + z >>> hpq.trunc_ground(p) == hp True >>> hpq.trunc_ground(q) == hq True """ hpmonoms = set(hp.monoms()) hqmonoms = set(hq.monoms()) monoms = hpmonoms.intersection(hqmonoms) hpmonoms.difference_update(monoms) hqmonoms.difference_update(monoms) zero = hp.ring.domain.zero hpq = hp.ring.zero if isinstance(hp.ring.domain, PolynomialRing): crt_ = _chinese_remainder_reconstruction_multivariate else: def crt_(cp, cq, p, q): return crt([p, q], [cp, cq], symmetric=True)[0] for monom in monoms: hpq[monom] = crt_(hp[monom], hq[monom], p, q) for monom in hpmonoms: hpq[monom] = crt_(hp[monom], zero, p, q) for monom in hqmonoms: hpq[monom] = crt_(zero, hq[monom], p, q) return hpq def _interpolate_multivariate(evalpoints, hpeval, ring, i, p, ground=False): r""" Reconstruct a polynomial `h_p` in `\mathbb{Z}_p[x_0, \ldots, x_{k-1}]` from a list of evaluation points in `\mathbb{Z}_p` and a list of polynomials in `\mathbb{Z}_p[x_0, \ldots, x_{i-1}, x_{i+1}, \ldots, x_{k-1}]`, which are the images of `h_p` evaluated in the variable `x_i`. It is also possible to reconstruct a parameter of the ground domain, i.e. if `h_p` is a polynomial over `\mathbb{Z}_p[x_0, \ldots, x_{k-1}]`. In this case, one has to set ``ground=True``. Parameters ========== evalpoints : list of Integer objects list of evaluation points in `\mathbb{Z}_p` hpeval : list of PolyElement objects list of polynomials in (resp. over) `\mathbb{Z}_p[x_0, \ldots, x_{i-1}, x_{i+1}, \ldots, x_{k-1}]`, images of `h_p` evaluated in the variable `x_i` ring : PolyRing `h_p` will be an element of this ring i : Integer index of the variable which has to be reconstructed p : Integer prime number, modulus of `h_p` ground : Boolean indicates whether `x_i` is in the ground domain, default is ``False`` Returns ======= hp : PolyElement interpolated polynomial in (resp. over) `\mathbb{Z}_p[x_0, \ldots, x_{k-1}]` """ hp = ring.zero if ground: domain = ring.domain.domain y = ring.domain.gens[i] else: domain = ring.domain y = ring.gens[i] for a, hpa in zip(evalpoints, hpeval): numer = ring.one denom = domain.one for b in evalpoints: if b == a: continue numer = y - b denom = a - b denom = domain.invert(denom, p) coeff = numer.mul_ground(denom) hp += hpa.set_ring(ring) * coeff return hp.trunc_ground(p) def modgcd_bivariate(f, g): r""" Computes the GCD of two polynomials in `\mathbb{Z}[x, y]` using a modular algorithm. The algorithm computes the GCD of two bivariate integer polynomials `f` and `g` by calculating the GCD in `\mathbb{Z}_p[x, y]` for suitable primes `p` and then reconstructing the coefficients with the Chinese Remainder Theorem. To compute the bivariate GCD over `\mathbb{Z}_p`, the polynomials `f \; \mathrm{mod} \, p` and `g \; \mathrm{mod} \, p` are evaluated at `y = a` for certain `a \in \mathbb{Z}_p` and then their univariate GCD in `\mathbb{Z}_p[x]` is computed. Interpolating those yields the bivariate GCD in `\mathbb{Z}_p[x, y]`. To verify the result in `\mathbb{Z}[x, y]`, trial division is done, but only for candidates which are very likely the desired GCD. Parameters ========== f : PolyElement bivariate integer polynomial g : PolyElement bivariate integer polynomial Returns ======= h : PolyElement GCD of the polynomials `f` and `g` cff : PolyElement cofactor of `f`, i.e. `\frac{f}{h}` cfg : PolyElement cofactor of `g`, i.e. `\frac{g}{h}` Examples ======== >>> from sympy.polys.modulargcd import modgcd_bivariate >>> from sympy.polys import ring, ZZ >>> R, x, y = ring("x, y", ZZ) >>> f = x2 - y2 >>> g = x*2 + 2xy + y2 >>> h, cff, cfg = modgcd_bivariate(f, g) >>> h, cff, cfg (x + y, x - y, x + y) >>> cff h == f True >>> cfg * h == g True >>> f = x*2y - x*2 - 4y + 4 >>> g = x + 2 >>> h, cff, cfg = modgcd_bivariate(f, g) >>> h, cff, cfg (x + 2, xy - x - 2y + 2, 1) >>> cff * h == f True >>> cfg * h == g True References ========== 1. [Monagan00]_ """ assert f.ring == g.ring and f.ring.domain.is_ZZ result = _trivial_gcd(f, g) if result is not None: return result ring = f.ring cf, f = f.primitive() cg, g = g.primitive() ch = ring.domain.gcd(cf, cg) xbound, ycontbound = _degree_bound_bivariate(f, g) if xbound == ycontbound == 0: return ring(ch), f.mul_ground(cf // ch), g.mul_ground(cg // ch) fswap = _swap(f, 1) gswap = _swap(g, 1) degyf = fswap.degree() degyg = gswap.degree() ybound, xcontbound = _degree_bound_bivariate(fswap, gswap) if ybound == xcontbound == 0: return ring(ch), f.mul_ground(cf // ch), g.mul_ground(cg // ch) # TODO: to improve performance, choose the main variable here gamma1 = ring.domain.gcd(f.LC, g.LC) gamma2 = ring.domain.gcd(fswap.LC, gswap.LC) badprimes = gamma1 * gamma2 m = 1 p = 1 while True: p = nextprime(p) while badprimes % p == 0: p = nextprime(p) fp = f.trunc_ground(p) gp = g.trunc_ground(p) contfp, fp = _primitive(fp, p) contgp, gp = _primitive(gp, p) conthp = _gf_gcd(contfp, contgp, p) # monic polynomial in Z_p[y] degconthp = conthp.degree() if degconthp > ycontbound: continue elif degconthp < ycontbound: m = 1 ycontbound = degconthp continue # polynomial in Z_p[y] delta = _gf_gcd(_LC(fp), _LC(gp), p) degcontfp = contfp.degree() degcontgp = contgp.degree() degdelta = delta.degree() N = min(degyf - degcontfp, degyg - degcontgp, ybound - ycontbound + degdelta) + 1 if p < N: continue n = 0 evalpoints = [] hpeval = [] unlucky = False for a in range(p): deltaa = delta.evaluate(0, a) if not deltaa % p: continue fpa = fp.evaluate(1, a).trunc_ground(p) gpa = gp.evaluate(1, a).trunc_ground(p) hpa = _gf_gcd(fpa, gpa, p) # monic polynomial in Z_p[x] deghpa = hpa.degree() if deghpa > xbound: continue elif deghpa < xbound: m = 1 xbound = deghpa unlucky = True break hpa = hpa.mul_ground(deltaa).trunc_ground(p) evalpoints.append(a) hpeval.append(hpa) n += 1 if n == N: break if unlucky: continue if n < N: continue hp = _interpolate_multivariate(evalpoints, hpeval, ring, 1, p) hp = _primitive(hp, p)[1] hp = hp * conthp.set_ring(ring) degyhp = hp.degree(1) if degyhp > ybound: continue if degyhp < ybound: m = 1 ybound = degyhp continue hp = hp.mul_ground(gamma1).trunc_ground(p) if m == 1: m = p hlastm = hp continue hm = _chinese_remainder_reconstruction_multivariate(hp, hlastm, p, m) m = p if not hm == hlastm: hlastm = hm continue h = hm.quo_ground(hm.content()) fquo, frem = f.div(h) gquo, grem = g.div(h) if not frem and not grem: if h.LC < 0: ch = -ch h = h.mul_ground(ch) cff = fquo.mul_ground(cf // ch) cfg = gquo.mul_ground(cg // ch) return h, cff, cfg def _modgcd_multivariate_p(f, g, p, degbound, contbound): r""" Compute the GCD of two polynomials in `\mathbb{Z}_p[x0, \ldots, x{k-1}]`. The algorithm reduces the problem step by step by evaluating the polynomials `f` and `g` at `x_{k-1} = a` for suitable `a \in \mathbb{Z}_p` and then calls itself recursively to compute the GCD in `\mathbb{Z}_p[x_0, \ldots, x_{k-2}]`. If these recursive calls are succsessful for enough evaluation points, the GCD in `k` variables is interpolated, otherwise the algorithm returns ``None``. Every time a GCD or a content is computed, their degrees are compared with the bounds. If a degree greater then the bound is encountered, then the current call returns ``None`` and a new evaluation point has to be chosen. If at some point the degree is smaller, the correspondent bound is updated and the algorithm fails. Parameters ========== f : PolyElement multivariate integer polynomial with coefficients in `\mathbb{Z}_p` g : PolyElement multivariate integer polynomial with coefficients in `\mathbb{Z}_p` p : Integer prime number, modulus of `f` and `g` degbound : list of Integer objects ``degbound[i]`` is an upper bound for the degree of the GCD of `f` and `g` in the variable `x_i` contbound : list of Integer objects ``contbound[i]`` is an upper bound for the degree of the content of the GCD in `\mathbb{Z}_p[x_i][x_0, \ldots, x_{i-1}]`, ``contbound[0]`` is not used can therefore be chosen arbitrarily. Returns ======= h : PolyElement GCD of the polynomials `f` and `g` or ``None`` References ========== 1. [Monagan00]_ 2. [Brown71]_ """ ring = f.ring k = ring.ngens if k == 1: h = _gf_gcd(f, g, p).trunc_ground(p) degh = h.degree() if degh > degbound[0]: return None if degh < degbound[0]: degbound[0] = degh raise ModularGCDFailed return h degyf = f.degree(k-1) degyg = g.degree(k-1) contf, f = _primitive(f, p) contg, g = _primitive(g, p) conth = _gf_gcd(contf, contg, p) # polynomial in Z_p[y] degcontf = contf.degree() degcontg = contg.degree() degconth = conth.degree() if degconth > contbound[k-1]: return None if degconth < contbound[k-1]: contbound[k-1] = degconth raise ModularGCDFailed lcf = _LC(f) lcg = _LC(g) delta = _gf_gcd(lcf, lcg, p) # polynomial in Z_p[y] evaltest = delta for i in range(k-1): evaltest = _gf_gcd(_LC(_swap(f, i)), _LC(_swap(g, i)), p) degdelta = delta.degree() N = min(degyf - degcontf, degyg - degcontg, degbound[k-1] - contbound[k-1] + degdelta) + 1 if p < N: return None n = 0 d = 0 evalpoints = [] heval = [] points = set(range(p)) while points: a = random.sample(points, 1)[0] points.remove(a) if not evaltest.evaluate(0, a) % p: continue deltaa = delta.evaluate(0, a) % p fa = f.evaluate(k-1, a).trunc_ground(p) ga = g.evaluate(k-1, a).trunc_ground(p) # polynomials in Z_p[x_0, ..., x_{k-2}] ha = _modgcd_multivariate_p(fa, ga, p, degbound, contbound) if ha is None: d += 1 if d > n: return None continue if ha.is_ground: h = conth.set_ring(ring).trunc_ground(p) return h ha = ha.mul_ground(deltaa).trunc_ground(p) evalpoints.append(a) heval.append(ha) n += 1 if n == N: h = _interpolate_multivariate(evalpoints, heval, ring, k-1, p) h = _primitive(h, p)[1] * conth.set_ring(ring) degyh = h.degree(k-1) if degyh > degbound[k-1]: return None if degyh < degbound[k-1]: degbound[k-1] = degyh raise ModularGCDFailed return h return None def modgcd_multivariate(f, g): r""" Compute the GCD of two polynomials in `\mathbb{Z}[x_0, \ldots, x_{k-1}]` using a modular algorithm. The algorithm computes the GCD of two multivariate integer polynomials `f` and `g` by calculating the GCD in `\mathbb{Z}_p[x_0, \ldots, x_{k-1}]` for suitable primes `p` and then reconstructing the coefficients with the Chinese Remainder Theorem. To compute the multivariate GCD over `\mathbb{Z}_p` the recursive subroutine ``_modgcd_multivariate_p`` is used. To verify the result in `\mathbb{Z}[x_0, \ldots, x_{k-1}]`, trial division is done, but only for candidates which are very likely the desired GCD. Parameters ========== f : PolyElement multivariate integer polynomial g : PolyElement multivariate integer polynomial Returns ======= h : PolyElement GCD of the polynomials `f` and `g` cff : PolyElement cofactor of `f`, i.e. `\frac{f}{h}` cfg : PolyElement cofactor of `g`, i.e. `\frac{g}{h}` Examples ======== >>> from sympy.polys.modulargcd import modgcd_multivariate >>> from sympy.polys import ring, ZZ >>> R, x, y = ring("x, y", ZZ) >>> f = x2 - y2 >>> g = x*2 + 2xy + y2 >>> h, cff, cfg = modgcd_multivariate(f, g) >>> h, cff, cfg (x + y, x - y, x + y) >>> cff h == f True >>> cfg * h == g True >>> R, x, y, z = ring("x, y, z", ZZ) >>> f = xz2 - yz2 >>> g = x2z + z >>> h, cff, cfg = modgcd_multivariate(f, g) >>> h, cff, cfg (z, xz - yz, x2 + 1) >>> cff h == f True >>> cfg * h == g True References ========== 1. [Monagan00]_ 2. [Brown71]_ See also ======== _modgcd_multivariate_p """ assert f.ring == g.ring and f.ring.domain.is_ZZ result = _trivial_gcd(f, g) if result is not None: return result ring = f.ring k = ring.ngens # divide out integer content cf, f = f.primitive() cg, g = g.primitive() ch = ring.domain.gcd(cf, cg) gamma = ring.domain.gcd(f.LC, g.LC) badprimes = ring.domain.one for i in range(k): badprimes = ring.domain.gcd(_swap(f, i).LC, _swap(g, i).LC) degbound = [min(fdeg, gdeg) for fdeg, gdeg in zip(f.degrees(), g.degrees())] contbound = list(degbound) m = 1 p = 1 while True: p = nextprime(p) while badprimes % p == 0: p = nextprime(p) fp = f.trunc_ground(p) gp = g.trunc_ground(p) try: # monic GCD of fp, gp in Z_p[x_0, ..., x_{k-2}, y] hp = _modgcd_multivariate_p(fp, gp, p, degbound, contbound) except ModularGCDFailed: m = 1 continue if hp is None: continue hp = hp.mul_ground(gamma).trunc_ground(p) if m == 1: m = p hlastm = hp continue hm = _chinese_remainder_reconstruction_multivariate(hp, hlastm, p, m) m = p if not hm == hlastm: hlastm = hm continue h = hm.primitive()[1] fquo, frem = f.div(h) gquo, grem = g.div(h) if not frem and not grem: if h.LC < 0: ch = -ch h = h.mul_ground(ch) cff = fquo.mul_ground(cf // ch) cfg = gquo.mul_ground(cg // ch) return h, cff, cfg def _gf_div(f, g, p): r""" Compute `\frac f g` modulo `p` for two univariate polynomials over `\mathbb Z_p`. """ ring = f.ring densequo, denserem = gf_div(f.to_dense(), g.to_dense(), p, ring.domain) return ring.from_dense(densequo), ring.from_dense(denserem) def _rational_function_reconstruction(c, p, m): r""" Reconstruct a rational function `\frac a b` in `\mathbb Z_p(t)` from .. math:: c = \frac a b \; \mathrm{mod} \, m, where `c` and `m` are polynomials in `\mathbb Z_p[t]` and `m` has positive degree. The algorithm is based on the Euclidean Algorithm. In general, `m` is not irreducible, so it is possible that `b` is not invertible modulo `m`. In that case ``None`` is returned. Parameters ========== c : PolyElement univariate polynomial in `\mathbb Z[t]` p : Integer prime number m : PolyElement modulus, not necessarily irreducible Returns ======= frac : FracElement either `\frac a b` in `\mathbb Z(t)` or ``None`` References ========== 1. [Hoeij04]_ """ ring = c.ring domain = ring.domain M = m.degree() N = M // 2 D = M - N - 1 r0, s0 = m, ring.zero r1, s1 = c, ring.one while r1.degree() > N: quo = _gf_div(r0, r1, p)[0] r0, r1 = r1, (r0 - quor1).trunc_ground(p) s0, s1 = s1, (s0 - quos1).trunc_ground(p) a, b = r1, s1 if b.degree() > D or _gf_gcd(b, m, p) != 1: return None lc = b.LC if lc != 1: lcinv = domain.invert(lc, p) a = a.mul_ground(lcinv).trunc_ground(p) b = b.mul_ground(lcinv).trunc_ground(p) field = ring.to_field() return field(a) / field(b) def _rational_reconstruction_func_coeffs(hm, p, m, ring, k): r""" Reconstruct every coefficient `c_h` of a polynomial `h` in `\mathbb Z_p(t_k)[t_1, \ldots, t_{k-1}][x, z]` from the corresponding coefficient `c_{h_m}` of a polynomial `h_m` in `\mathbb Z_p[t_1, \ldots, t_k][x, z] \cong \mathbb Z_p[t_k][t_1, \ldots, t_{k-1}][x, z]` such that .. math:: c_{h_m} = c_h \; \mathrm{mod} \, m, where `m \in \mathbb Z_p[t]`. The reconstruction is based on the Euclidean Algorithm. In general, `m` is not irreducible, so it is possible that this fails for some coefficient. In that case ``None`` is returned. Parameters ========== hm : PolyElement polynomial in `\mathbb Z[t_1, \ldots, t_k][x, z]` p : Integer prime number, modulus of `\mathbb Z_p` m : PolyElement modulus, polynomial in `\mathbb Z[t]`, not necessarily irreducible ring : PolyRing `\mathbb Z(t_k)[t_1, \ldots, t_{k-1}][x, z]`, `h` will be an element of this ring k : Integer index of the parameter `t_k` which will be reconstructed Returns ======= h : PolyElement reconstructed polynomial in `\mathbb Z(t_k)[t_1, \ldots, t_{k-1}][x, z]` or ``None`` See also ======== _rational_function_reconstruction """ h = ring.zero for monom, coeff in hm.iterterms(): if k == 0: coeffh = _rational_function_reconstruction(coeff, p, m) if not coeffh: return None else: coeffh = ring.domain.zero for mon, c in coeff.drop_to_ground(k).iterterms(): ch = _rational_function_reconstruction(c, p, m) if not ch: return None coeffh[mon] = ch h[monom] = coeffh return h def _gf_gcdex(f, g, p): r""" Extended Euclidean Algorithm for two univariate polynomials over `\mathbb Z_p`. Returns polynomials `s, t` and `h`, such that `h` is the GCD of `f` and `g` and `sf + tg = h \; \mathrm{mod} \, p`. """ ring = f.ring s, t, h = gf_gcdex(f.to_dense(), g.to_dense(), p, ring.domain) return ring.from_dense(s), ring.from_dense(t), ring.from_dense(h) def _trunc(f, minpoly, p): r""" Compute the reduced representation of a polynomial `f` in `\mathbb Z_p[z] / (\check m_{\alpha}(z))[x]` Parameters ========== f : PolyElement polynomial in `\mathbb Z[x, z]` minpoly : PolyElement polynomial `\check m_{\alpha} \in \mathbb Z[z]`, not necessarily irreducible p : Integer prime number, modulus of `\mathbb Z_p` Returns ======= ftrunc : PolyElement polynomial in `\mathbb Z[x, z]`, reduced modulo `\check m_{\alpha}(z)` and `p` """ ring = f.ring minpoly = minpoly.set_ring(ring) p_ = ring.ground_new(p) return f.trunc_ground(p).rem([minpoly, p_]).trunc_ground(p) def _euclidean_algorithm(f, g, minpoly, p): r""" Compute the monic GCD of two univariate polynomials in `\mathbb{Z}_p[z]/(\check m_{\alpha}(z))[x]` with the Euclidean Algorithm. In general, `\check m_{\alpha}(z)` is not irreducible, so it is possible that some leading coefficient is not invertible modulo `\check m_{\alpha}(z)`. In that case ``None`` is returned. Parameters ========== f, g : PolyElement polynomials in `\mathbb Z[x, z]` minpoly : PolyElement polynomial in `\mathbb Z[z]`, not necessarily irreducible p : Integer prime number, modulus of `\mathbb Z_p` Returns ======= h : PolyElement GCD of `f` and `g` in `\mathbb Z[z, x]` or ``None``, coefficients are in `\left[ -\frac{p-1} 2, \frac{p-1} 2 \right]` """ ring = f.ring f = _trunc(f, minpoly, p) g = _trunc(g, minpoly, p) while g: rem = f deg = g.degree(0) # degree in x lcinv, _, gcd = _gf_gcdex(ring.dmp_LC(g), minpoly, p) if not gcd == 1: return None while True: degrem = rem.degree(0) # degree in x if degrem < deg: break quo = (lcinv * ring.dmp_LC(rem)).set_ring(ring) rem = _trunc(rem - g.mul_monom((degrem - deg, 0))quo, minpoly, p) f = g g = rem lcfinv = _gf_gcdex(ring.dmp_LC(f), minpoly, p)[0].set_ring(ring) return _trunc(f lcfinv, minpoly, p) def _trial_division(f, h, minpoly, p=None): r""" Check if `h` divides `f` in `\mathbb K[t_1, \ldots, t_k][z]/(m_{\alpha}(z))`, where `\mathbb K` is either `\mathbb Q` or `\mathbb Z_p`. This algorithm is based on pseudo division and does not use any fractions. By default `\mathbb K` is `\mathbb Q`, if a prime number `p` is given, `\mathbb Z_p` is chosen instead. Parameters ========== f, h : PolyElement polynomials in `\mathbb Z[t_1, \ldots, t_k][x, z]` minpoly : PolyElement polynomial `m_{\alpha}(z)` in `\mathbb Z[t_1, \ldots, t_k][z]` p : Integer or None if `p` is given, `\mathbb K` is set to `\mathbb Z_p` instead of `\mathbb Q`, default is ``None`` Returns ======= rem : PolyElement remainder of `\frac f h` References ========== .. [1] [Hoeij02]_ """ ring = f.ring zxring = ring.clone(symbols=(ring.symbols[1], ring.symbols[0])) minpoly = minpoly.set_ring(ring) rem = f degrem = rem.degree() degh = h.degree() degm = minpoly.degree(1) lch = _LC(h).set_ring(ring) lcm = minpoly.LC while rem and degrem >= degh: # polynomial in Z[t_1, ..., t_k][z] lcrem = _LC(rem).set_ring(ring) rem = remlch - h.mul_monom((degrem - degh, 0))lcrem if p: rem = rem.trunc_ground(p) degrem = rem.degree(1) while rem and degrem >= degm: # polynomial in Z[t_1, ..., t_k][x] lcrem = _LC(rem.set_ring(zxring)).set_ring(ring) rem = rem.mul_ground(lcm) - minpoly.mul_monom((0, degrem - degm))lcrem if p: rem = rem.trunc_ground(p) degrem = rem.degree(1) degrem = rem.degree() return rem def _evaluate_ground(f, i, a): r""" Evaluate a polynomial `f` at `a` in the `i`-th variable of the ground domain. """ ring = f.ring.clone(domain=f.ring.domain.ring.drop(i)) fa = ring.zero for monom, coeff in f.iterterms(): fa[monom] = coeff.evaluate(i, a) return fa def _func_field_modgcd_p(f, g, minpoly, p): r""" Compute the GCD of two polynomials `f` and `g` in `\mathbb Z_p(t_1, \ldots, t_k)[z]/(\check m_\alpha(z))[x]`. The algorithm reduces the problem step by step by evaluating the polynomials `f` and `g` at `t_k = a` for suitable `a \in \mathbb Z_p` and then calls itself recursively to compute the GCD in `\mathbb Z_p(t_1, \ldots, t_{k-1})[z]/(\check m_\alpha(z))[x]`. If these recursive calls are successful, the GCD over `k` variables is interpolated, otherwise the algorithm returns ``None``. After interpolation, Rational Function Reconstruction is used to obtain the correct coefficients. If this fails, a new evaluation point has to be chosen, otherwise the desired polynomial is obtained by clearing denominators. The result is verified with a fraction free trial division. Parameters ========== f, g : PolyElement polynomials in `\mathbb Z[t_1, \ldots, t_k][x, z]` minpoly : PolyElement polynomial in `\mathbb Z[t_1, \ldots, t_k][z]`, not necessarily irreducible p : Integer prime number, modulus of `\mathbb Z_p` Returns ======= h : PolyElement primitive associate in `\mathbb Z[t_1, \ldots, t_k][x, z]` of the GCD of the polynomials `f` and `g` or ``None``, coefficients are in `\left[ -\frac{p-1} 2, \frac{p-1} 2 \right]` References ========== 1. [Hoeij04]_ """ ring = f.ring domain = ring.domain # Z[t_1, ..., t_k] if isinstance(domain, PolynomialRing): k = domain.ngens else: return _euclidean_algorithm(f, g, minpoly, p) if k == 1: qdomain = domain.ring.to_field() else: qdomain = domain.ring.drop_to_ground(k - 1) qdomain = qdomain.clone(domain=qdomain.domain.ring.to_field()) qring = ring.clone(domain=qdomain) # = Z(t_k)[t_1, ..., t_{k-1}][x, z] n = 1 d = 1 # polynomial in Z_p[t_1, ..., t_k][z] gamma = ring.dmp_LC(f) ring.dmp_LC(g) # polynomial in Z_p[t_1, ..., t_k] delta = minpoly.LC evalpoints = [] heval = [] LMlist = [] points = set(range(p)) while points: a = random.sample(points, 1)[0] points.remove(a) if k == 1: test = delta.evaluate(k-1, a) % p == 0 else: test = delta.evaluate(k-1, a).trunc_ground(p) == 0 if test: continue gammaa = _evaluate_ground(gamma, k-1, a) minpolya = _evaluate_ground(minpoly, k-1, a) if gammaa.rem([minpolya, gammaa.ring(p)]) == 0: continue fa = _evaluate_ground(f, k-1, a) ga = _evaluate_ground(g, k-1, a) # polynomial in Z_p[x, t_1, ..., t_{k-1}, z]/(minpoly) ha = _func_field_modgcd_p(fa, ga, minpolya, p) if ha is None: d += 1 if d > n: return None continue if ha == 1: return ha LM = [ha.degree()] + [0](k-1) if k > 1: for monom, coeff in ha.iterterms(): if monom[0] == LM[0] and coeff.LM > tuple(LM[1:]): LM[1:] = coeff.LM evalpoints_a = [a] heval_a = [ha] if k == 1: m = qring.domain.get_ring().one else: m = qring.domain.domain.get_ring().one t = m.ring.gens[0] for b, hb, LMhb in zip(evalpoints, heval, LMlist): if LMhb == LM: evalpoints_a.append(b) heval_a.append(hb) m = (t - b) m = m.trunc_ground(p) evalpoints.append(a) heval.append(ha) LMlist.append(LM) n += 1 # polynomial in Z_p[t_1, ..., t_k][x, z] h = _interpolate_multivariate(evalpoints_a, heval_a, ring, k-1, p, ground=True) # polynomial in Z_p(t_k)[t_1, ..., t_{k-1}][x, z] h = _rational_reconstruction_func_coeffs(h, p, m, qring, k-1) if h is None: continue if k == 1: dom = qring.domain.field den = dom.ring.one for coeff in h.itercoeffs(): den = dom.ring.from_dense(gf_lcm(den.to_dense(), coeff.denom.to_dense(), p, dom.domain)) else: dom = qring.domain.domain.field den = dom.ring.one for coeff in h.itercoeffs(): for c in coeff.itercoeffs(): den = dom.ring.from_dense(gf_lcm(den.to_dense(), c.denom.to_dense(), p, dom.domain)) den = qring.domain_new(den.trunc_ground(p)) h = ring(h.mul_ground(den).as_expr()).trunc_ground(p) if not _trial_division(f, h, minpoly, p) and not _trial_division(g, h, minpoly, p): return h return None def _integer_rational_reconstruction(c, m, domain): r""" Reconstruct a rational number `\frac a b` from .. math:: c = \frac a b \; \mathrm{mod} \, m, where `c` and `m` are integers. The algorithm is based on the Euclidean Algorithm. In general, `m` is not a prime number, so it is possible that `b` is not invertible modulo `m`. In that case ``None`` is returned. Parameters ========== c : Integer `c = \frac a b \; \mathrm{mod} \, m` m : Integer modulus, not necessarily prime domain : IntegerRing `a, b, c` are elements of ``domain`` Returns ======= frac : Rational either `\frac a b` in `\mathbb Q` or ``None`` References ========== 1. [Wang81]_ """ if c < 0: c += m r0, s0 = m, domain.zero r1, s1 = c, domain.one bound = sqrt(m / 2) # still correct if replaced by ZZ.sqrt(m // 2) ? while r1 >= bound: quo = r0 // r1 r0, r1 = r1, r0 - quor1 s0, s1 = s1, s0 - quos1 if abs(s1) >= bound: return None if s1 < 0: a, b = -r1, -s1 elif s1 > 0: a, b = r1, s1 else: return None field = domain.get_field() return field(a) / field(b) def _rational_reconstruction_int_coeffs(hm, m, ring): r""" Reconstruct every rational coefficient `c_h` of a polynomial `h` in `\mathbb Q[t_1, \ldots, t_k][x, z]` from the corresponding integer coefficient `c_{h_m}` of a polynomial `h_m` in `\mathbb Z[t_1, \ldots, t_k][x, z]` such that .. math:: c_{h_m} = c_h \; \mathrm{mod} \, m, where `m \in \mathbb Z`. The reconstruction is based on the Euclidean Algorithm. In general, `m` is not a prime number, so it is possible that this fails for some coefficient. In that case ``None`` is returned. Parameters ========== hm : PolyElement polynomial in `\mathbb Z[t_1, \ldots, t_k][x, z]` m : Integer modulus, not necessarily prime ring : PolyRing `\mathbb Q[t_1, \ldots, t_k][x, z]`, `h` will be an element of this ring Returns ======= h : PolyElement reconstructed polynomial in `\mathbb Q[t_1, \ldots, t_k][x, z]` or ``None`` See also ======== _integer_rational_reconstruction """ h = ring.zero if isinstance(ring.domain, PolynomialRing): reconstruction = _rational_reconstruction_int_coeffs domain = ring.domain.ring else: reconstruction = _integer_rational_reconstruction domain = hm.ring.domain for monom, coeff in hm.iterterms(): coeffh = reconstruction(coeff, m, domain) if not coeffh: return None h[monom] = coeffh return h def _func_field_modgcd_m(f, g, minpoly): r""" Compute the GCD of two polynomials in `\mathbb Q(t_1, \ldots, t_k)[z]/(m_{\alpha}(z))[x]` using a modular algorithm. The algorithm computes the GCD of two polynomials `f` and `g` by calculating the GCD in `\mathbb Z_p(t_1, \ldots, t_k)[z] / (\check m_{\alpha}(z))[x]` for suitable primes `p` and the primitive associate `\check m_{\alpha}(z)` of `m_{\alpha}(z)`. Then the coefficients are reconstructed with the Chinese Remainder Theorem and Rational Reconstruction. To compute the GCD over `\mathbb Z_p(t_1, \ldots, t_k)[z] / (\check m_{\alpha})[x]`, the recursive subroutine ``_func_field_modgcd_p`` is used. To verify the result in `\mathbb Q(t_1, \ldots, t_k)[z] / (m_{\alpha}(z))[x]`, a fraction free trial division is used. Parameters ========== f, g : PolyElement polynomials in `\mathbb Z[t_1, \ldots, t_k][x, z]` minpoly : PolyElement irreducible polynomial in `\mathbb Z[t_1, \ldots, t_k][z]` Returns ======= h : PolyElement the primitive associate in `\mathbb Z[t_1, \ldots, t_k][x, z]` of the GCD of `f` and `g` Examples ======== >>> from sympy.polys.modulargcd import _func_field_modgcd_m >>> from sympy.polys import ring, ZZ >>> R, x, z = ring('x, z', ZZ) >>> minpoly = (z2 - 2).drop(0) >>> f = x2 + 2xz + 2 >>> g = x + z >>> _func_field_modgcd_m(f, g, minpoly) x + z >>> D, t = ring('t', ZZ) >>> R, x, z = ring('x, z', D) >>> minpoly = (z2-3).drop(0) >>> f = x2 + (t + 1)xz + 3t >>> g = xz + 3t >>> _func_field_modgcd_m(f, g, minpoly) x + tz References ========== 1. [Hoeij04]_ See also ======== _func_field_modgcd_p """ ring = f.ring domain = ring.domain if isinstance(domain, PolynomialRing): k = domain.ngens QQdomain = domain.ring.clone(domain=domain.domain.get_field()) QQring = ring.clone(domain=QQdomain) else: k = 0 QQring = ring.clone(domain=ring.domain.get_field()) cf, f = f.primitive() cg, g = g.primitive() # polynomial in Z[t_1, ..., t_k][z] gamma = ring.dmp_LC(f) * ring.dmp_LC(g) # polynomial in Z[t_1, ..., t_k] delta = minpoly.LC p = 1 primes = [] hplist = [] LMlist = [] while True: p = nextprime(p) if gamma.trunc_ground(p) == 0: continue if k == 0: test = (delta % p == 0) else: test = (delta.trunc_ground(p) == 0) if test: continue fp = f.trunc_ground(p) gp = g.trunc_ground(p) minpolyp = minpoly.trunc_ground(p) hp = _func_field_modgcd_p(fp, gp, minpolyp, p) if hp is None: continue if hp == 1: return ring.one LM = [hp.degree()] + [0]k if k > 0: for monom, coeff in hp.iterterms(): if monom[0] == LM[0] and coeff.LM > tuple(LM[1:]): LM[1:] = coeff.LM hm = hp m = p for q, hq, LMhq in zip(primes, hplist, LMlist): if LMhq == LM: hm = _chinese_remainder_reconstruction_multivariate(hq, hm, q, m) m = q primes.append(p) hplist.append(hp) LMlist.append(LM) hm = _rational_reconstruction_int_coeffs(hm, m, QQring) if hm is None: continue if k == 0: h = hm.clear_denoms()[1] else: den = domain.domain.one for coeff in hm.itercoeffs(): den = domain.domain.lcm(den, coeff.clear_denoms()[0]) h = hm.mul_ground(den) # convert back to Z[t_1, ..., t_k][x, z] from Q[t_1, ..., t_k][x, z] h = h.set_ring(ring) h = h.primitive()[1] if not (_trial_division(f.mul_ground(cf), h, minpoly) or _trial_division(g.mul_ground(cg), h, minpoly)): return h def _to_ZZ_poly(f, ring): r""" Compute an associate of a polynomial `f \in \mathbb Q(\alpha)[x_0, \ldots, x_{n-1}]` in `\mathbb Z[x_1, \ldots, x_{n-1}][z] / (\check m_{\alpha}(z))[x_0]`, where `\check m_{\alpha}(z) \in \mathbb Z[z]` is the primitive associate of the minimal polynomial `m_{\alpha}(z)` of `\alpha` over `\mathbb Q`. Parameters ========== f : PolyElement polynomial in `\mathbb Q(\alpha)[x_0, \ldots, x_{n-1}]` ring : PolyRing `\mathbb Z[x_1, \ldots, x_{n-1}][x_0, z]` Returns ======= f_ : PolyElement associate of `f` in `\mathbb Z[x_1, \ldots, x_{n-1}][x_0, z]` """ f_ = ring.zero if isinstance(ring.domain, PolynomialRing): domain = ring.domain.domain else: domain = ring.domain den = domain.one for coeff in f.itercoeffs(): for c in coeff.rep: if c: den = domain.lcm(den, c.denominator) for monom, coeff in f.iterterms(): coeff = coeff.rep m = ring.domain.one if isinstance(ring.domain, PolynomialRing): m = m.mul_monom(monom[1:]) n = len(coeff) for i in range(n): if coeff[i]: c = domain(coeff[i] * den) * m if (monom[0], n-i-1) not in f_: f_[(monom[0], n-i-1)] = c else: f_[(monom[0], n-i-1)] += c return f_ def _to_ANP_poly(f, ring): r""" Convert a polynomial `f \in \mathbb Z[x_1, \ldots, x_{n-1}][z]/(\check m_{\alpha}(z))[x_0]` to a polynomial in `\mathbb Q(\alpha)[x_0, \ldots, x_{n-1}]`, where `\check m_{\alpha}(z) \in \mathbb Z[z]` is the primitive associate of the minimal polynomial `m_{\alpha}(z)` of `\alpha` over `\mathbb Q`. Parameters ========== f : PolyElement polynomial in `\mathbb Z[x_1, \ldots, x_{n-1}][x_0, z]` ring : PolyRing `\mathbb Q(\alpha)[x_0, \ldots, x_{n-1}]` Returns ======= f_ : PolyElement polynomial in `\mathbb Q(\alpha)[x_0, \ldots, x_{n-1}]` """ domain = ring.domain f_ = ring.zero if isinstance(f.ring.domain, PolynomialRing): for monom, coeff in f.iterterms(): for mon, coef in coeff.iterterms(): m = (monom[0],) + mon c = domain([domain.domain(coef)] + [0]monom[1]) if m not in f_: f_[m] = c else: f_[m] += c else: for monom, coeff in f.iterterms(): m = (monom[0],) c = domain([domain.domain(coeff)] + [0]monom[1]) if m not in f_: f_[m] = c else: f_[m] += c return f_ def _minpoly_from_dense(minpoly, ring): r""" Change representation of the minimal polynomial from ``DMP`` to ``PolyElement`` for a given ring. """ minpoly_ = ring.zero for monom, coeff in minpoly.terms(): minpoly_[monom] = ring.domain(coeff) return minpoly_ def _primitive_in_x0(f): r""" Compute the content in `x_0` and the primitive part of a polynomial `f` in `\mathbb Q(\alpha)[x_0, x_1, \ldots, x_{n-1}] \cong \mathbb Q(\alpha)[x_1, \ldots, x_{n-1}][x_0]`. """ fring = f.ring ring = fring.drop_to_ground(range(1, fring.ngens)) dom = ring.domain.ring f_ = ring(f.as_expr()) cont = dom.zero for coeff in f_.itercoeffs(): cont = func_field_modgcd(cont, coeff)[0] if cont == dom.one: return cont, f return cont, f.quo(cont.set_ring(fring)) # TODO: add support for algebraic function fields def func_field_modgcd(f, g): r""" Compute the GCD of two polynomials `f` and `g` in `\mathbb Q(\alpha)[x_0, \ldots, x_{n-1}]` using a modular algorithm. The algorithm first computes the primitive associate `\check m_{\alpha}(z)` of the minimal polynomial `m_{\alpha}` in `\mathbb{Z}[z]` and the primitive associates of `f` and `g` in `\mathbb{Z}[x_1, \ldots, x_{n-1}][z]/(\check m_{\alpha})[x_0]`. Then it computes the GCD in `\mathbb Q(x_1, \ldots, x_{n-1})[z]/(m_{\alpha}(z))[x_0]`. This is done by calculating the GCD in `\mathbb{Z}_p(x_1, \ldots, x_{n-1})[z]/(\check m_{\alpha}(z))[x_0]` for suitable primes `p` and then reconstructing the coefficients with the Chinese Remainder Theorem and Rational Reconstuction. The GCD over `\mathbb{Z}_p(x_1, \ldots, x_{n-1})[z]/(\check m_{\alpha}(z))[x_0]` is computed with a recursive subroutine, which evaluates the polynomials at `x_{n-1} = a` for suitable evaluation points `a \in \mathbb Z_p` and then calls itself recursively until the ground domain does no longer contain any parameters. For `\mathbb{Z}_p[z]/(\check m_{\alpha}(z))[x_0]` the Euclidean Algorithm is used. The results of those recursive calls are then interpolated and Rational Function Reconstruction is used to obtain the correct coefficients. The results, both in `\mathbb Q(x_1, \ldots, x_{n-1})[z]/(m_{\alpha}(z))[x_0]` and `\mathbb{Z}_p(x_1, \ldots, x_{n-1})[z]/(\check m_{\alpha}(z))[x_0]`, are verified by a fraction free trial division. Apart from the above GCD computation some GCDs in `\mathbb Q(\alpha)[x_1, \ldots, x_{n-1}]` have to be calculated, because treating the polynomials as univariate ones can result in a spurious content of the GCD. For this ``func_field_modgcd`` is called recursively. Parameters ========== f, g : PolyElement polynomials in `\mathbb Q(\alpha)[x_0, \ldots, x_{n-1}]` Returns ======= h : PolyElement monic GCD of the polynomials `f` and `g` cff : PolyElement cofactor of `f`, i.e. `\frac f h` cfg : PolyElement cofactor of `g`, i.e. `\frac g h` Examples ======== >>> from sympy.polys.modulargcd import func_field_modgcd >>> from sympy.polys import AlgebraicField, QQ, ring >>> from sympy import sqrt >>> A = AlgebraicField(QQ, sqrt(2)) >>> R, x = ring('x', A) >>> f = x2 - 2 >>> g = x + sqrt(2) >>> h, cff, cfg = func_field_modgcd(f, g) >>> h == x + sqrt(2) True >>> cff h == f True >>> cfg * h == g True >>> R, x, y = ring('x, y', A) >>> f = x*2 + 2sqrt(2)xy + 2y2 >>> g = x + sqrt(2)y >>> h, cff, cfg = func_field_modgcd(f, g) >>> h == x + sqrt(2)y True >>> cff h == f True >>> cfg * h == g True >>> f = x + sqrt(2)y >>> g = x + y >>> h, cff, cfg = func_field_modgcd(f, g) >>> h == R.one True >>> cff h == f True >>> cfg * h == g True References ========== 1. [Hoeij04]_ """ ring = f.ring domain = ring.domain n = ring.ngens assert ring == g.ring and domain.is_Algebraic result = _trivial_gcd(f, g) if result is not None: return result z = Dummy('z') ZZring = ring.clone(symbols=ring.symbols + (z,), domain=domain.domain.get_ring()) if n == 1: f_ = _to_ZZ_poly(f, ZZring) g_ = _to_ZZ_poly(g, ZZring) minpoly = ZZring.drop(0).from_dense(domain.mod.rep) h = _func_field_modgcd_m(f_, g_, minpoly) h = _to_ANP_poly(h, ring) else: # contx0f in Q(a)[x_1, ..., x_{n-1}], f in Q(a)[x_0, ..., x_{n-1}] contx0f, f = _primitive_in_x0(f) contx0g, g = _primitive_in_x0(g) contx0h = func_field_modgcd(contx0f, contx0g)[0] ZZring_ = ZZring.drop_to_ground(range(1, n)) f_ = _to_ZZ_poly(f, ZZring_) g_ = _to_ZZ_poly(g, ZZring_) minpoly = _minpoly_from_dense(domain.mod, ZZring_.drop(0)) h = _func_field_modgcd_m(f_, g_, minpoly) h = _to_ANP_poly(h, ring) contx0h_, h = _primitive_in_x0(h) h = contx0h.set_ring(ring) f = contx0f.set_ring(ring) g = contx0g.set_ring(ring) h = h.quo_ground(h.LC) return h, f.quo(h), g.quo(h)
a55287f0cc9a3ebaab4b45b18e365118ce55519294ee6268f5ce2e14faec229b	"""High-level polynomials manipulation functions. """ from __future__ import print_function, division from sympy.core import S, Basic, Add, Mul, symbols from sympy.core.compatibility import range from sympy.functions.combinatorial.factorials import factorial from sympy.polys.polyerrors import ( PolificationFailed, ComputationFailed, MultivariatePolynomialError, OptionError) from sympy.polys.polyoptions import allowed_flags from sympy.polys.polytools import ( poly_from_expr, parallel_poly_from_expr, Poly) from sympy.polys.specialpolys import ( symmetric_poly, interpolating_poly) from sympy.utilities import numbered_symbols, take, public @public def symmetrize(F, gens, args): """ Rewrite a polynomial in terms of elementary symmetric polynomials. A symmetric polynomial is a multivariate polynomial that remains invariant under any variable permutation, i.e., if ``f = f(x_1, x_2, ..., x_n)``, then ``f = f(x_{i_1}, x_{i_2}, ..., x_{i_n})``, where ``(i_1, i_2, ..., i_n)`` is a permutation of ``(1, 2, ..., n)`` (an element of the group ``S_n``). Returns a tuple of symmetric polynomials ``(f1, f2, ..., fn)`` such that ``f = f1 + f2 + ... + fn``. Examples ======== >>> from sympy.polys.polyfuncs import symmetrize >>> from sympy.abc import x, y >>> symmetrize(x2 + y2) (-2xy + (x + y)2, 0) >>> symmetrize(x2 + y2, formal=True) (s12 - 2s2, 0, [(s1, x + y), (s2, xy)]) >>> symmetrize(x2 - y2) (-2xy + (x + y)2, -2y2) >>> symmetrize(x2 - y2, formal=True) (s12 - 2s2, -2y*2, [(s1, x + y), (s2, xy)]) """ allowed_flags(args, ['formal', 'symbols']) iterable = True if not hasattr(F, '__iter__'): iterable = False F = [F] try: F, opt = parallel_poly_from_expr(F, gens, args) except PolificationFailed as exc: result = [] for expr in exc.exprs: if expr.is_Number: result.append((expr, S.Zero)) else: raise ComputationFailed('symmetrize', len(F), exc) else: if not iterable: result, = result if not exc.opt.formal: return result else: if iterable: return result, [] else: return result + ([],) polys, symbols = [], opt.symbols gens, dom = opt.gens, opt.domain for i in range(len(gens)): poly = symmetric_poly(i + 1, gens, polys=True) polys.append((next(symbols), poly.set_domain(dom))) indices = list(range(len(gens) - 1)) weights = list(range(len(gens), 0, -1)) result = [] for f in F: symmetric = [] if not f.is_homogeneous: symmetric.append(f.TC()) f -= f.TC() while f: _height, _monom, _coeff = -1, None, None for i, (monom, coeff) in enumerate(f.terms()): if all(monom[i] >= monom[i + 1] for i in indices): height = max([nm for n, m in zip(weights, monom)]) if height > _height: _height, _monom, _coeff = height, monom, coeff if _height != -1: monom, coeff = _monom, _coeff else: break exponents = [] for m1, m2 in zip(monom, monom[1:] + (0,)): exponents.append(m1 - m2) term = [sn for (s, _), n in zip(polys, exponents)] poly = [pn for (_, p), n in zip(polys, exponents)] symmetric.append(Mul(coeff, term)) product = poly[0].mul(coeff) for p in poly[1:]: product = product.mul(p) f -= product result.append((Add(symmetric), f.as_expr())) polys = [(s, p.as_expr()) for s, p in polys] if not opt.formal: for i, (sym, non_sym) in enumerate(result): result[i] = (sym.subs(polys), non_sym) if not iterable: result, = result if not opt.formal: return result else: if iterable: return result, polys else: return result + (polys,) @public def horner(f, gens, args): """ Rewrite a polynomial in Horner form. Among other applications, evaluation of a polynomial at a point is optimal when it is applied using the Horner scheme ([1]). Examples ======== >>> from sympy.polys.polyfuncs import horner >>> from sympy.abc import x, y, a, b, c, d, e >>> horner(9x*4 + 8x*3 + 7x*2 + 6x + 5) x(x(x(9x + 8) + 7) + 6) + 5 >>> horner(ax4 + bx*3 + cx*2 + dx + e) e + x(d + x(c + x(ax + b))) >>> f = 4x2y*2 + 2x*2y + 2xy*2 + xy >>> horner(f, wrt=x) x(xy(4y + 2) + y(2y + 1)) >>> horner(f, wrt=y) y(xy(4x + 2) + x(2x + 1)) References ========== [1] - https://en.wikipedia.org/wiki/Horner_scheme """ allowed_flags(args, []) try: F, opt = poly_from_expr(f, gens, args) except PolificationFailed as exc: return exc.expr form, gen = S.Zero, F.gen if F.is_univariate: for coeff in F.all_coeffs(): form = formgen + coeff else: F, gens = Poly(F, gen), gens[1:] for coeff in F.all_coeffs(): form = formgen + horner(coeff, gens, args) return form @public def interpolate(data, x): """ Construct an interpolating polynomial for the data points. Examples ======== >>> from sympy.polys.polyfuncs import interpolate >>> from sympy.abc import x A list is interpreted as though it were paired with a range starting from 1: >>> interpolate([1, 4, 9, 16], x) x2 This can be made explicit by giving a list of coordinates: >>> interpolate([(1, 1), (2, 4), (3, 9)], x) x2 The (x, y) coordinates can also be given as keys and values of a dictionary (and the points need not be equispaced): >>> interpolate([(-1, 2), (1, 2), (2, 5)], x) x2 + 1 >>> interpolate({-1: 2, 1: 2, 2: 5}, x) x*2 + 1 """ n = len(data) poly = None if isinstance(data, dict): X, Y = list(zip(data.items())) poly = interpolating_poly(n, x, X, Y) else: if isinstance(data[0], tuple): X, Y = list(zip(data)) poly = interpolating_poly(n, x, X, Y) else: Y = list(data) numert = Mul([(x - i) for i in range(1, n + 1)]) denom = -factorial(n - 1) if n%2 == 0 else factorial(n - 1) coeffs = [] for i in range(1, n + 1): coeffs.append(numert/(x - i)/denom) denom = denom/(i - n)i poly = Add([coeffy for coeff, y in zip(coeffs, Y)]) return poly.expand() @public def rational_interpolate(data, degnum, X=symbols('x')): """ Returns a rational interpolation, where the data points are element of any integral domain. The first argument contains the data (as a list of coordinates). The ``degnum`` argument is the degree in the numerator of the rational function. Setting it too high will decrease the maximal degree in the denominator for the same amount of data. Examples ======== >>> from sympy.polys.polyfuncs import rational_interpolate >>> data = [(1, -210), (2, -35), (3, 105), (4, 231), (5, 350), (6, 465)] >>> rational_interpolate(data, 2) (105x*2 - 525)/(x + 1) Values do not need to be integers: >>> from sympy import sympify >>> x = [1, 2, 3, 4, 5, 6] >>> y = sympify("[-1, 0, 2, 22/5, 7, 68/7]") >>> rational_interpolate(zip(x, y), 2) (3x*2 - 7x + 2)/(x + 1) The symbol for the variable can be changed if needed: >>> from sympy import symbols >>> z = symbols('z') >>> rational_interpolate(data, 2, X=z) (105z2 - 525)/(z + 1) References ========== .. [1] Algorithm is adapted from: http://axiom-wiki.newsynthesis.org/RationalInterpolation """ from sympy.matrices.dense import ones xdata, ydata = list(zip(data)) k = len(xdata) - degnum - 1 if k < 0: raise OptionError("Too few values for the required degree.") c = ones(degnum + k + 1, degnum + k + 2) for j in range(max(degnum, k)): for i in range(degnum + k + 1): c[i, j + 1] = c[i, j]xdata[i] for j in range(k + 1): for i in range(degnum + k + 1): c[i, degnum + k + 1 - j] = -c[i, k - j]ydata[i] r = c.nullspace()[0] return (sum(r[i] * X*i for i in range(degnum + 1)) / sum(r[i + degnum + 1] X*i for i in range(k + 1))) @public def viete(f, roots=None, gens, *args): """ Generate Viete's formulas for ``f``. Examples ======== >>> from sympy.polys.polyfuncs import viete >>> from sympy import symbols >>> x, a, b, c, r1, r2 = symbols('x,a:c,r1:3') >>> viete(ax*2 + bx + c, [r1, r2], x) [(r1 + r2, -b/a), (r1r2, c/a)] """ allowed_flags(args, []) if isinstance(roots, Basic): gens, roots = (roots,) + gens, None try: f, opt = poly_from_expr(f, gens, *args) except PolificationFailed as exc: raise ComputationFailed('viete', 1, exc) if f.is_multivariate: raise MultivariatePolynomialError( "multivariate polynomials are not allowed") n = f.degree() if n < 1: raise ValueError( "can't derive Viete's formulas for a constant polynomial") if roots is None: roots = numbered_symbols('r', start=1) roots = take(roots, n) if n != len(roots): raise ValueError("required %s roots, got %s" % (n, len(roots))) lc, coeffs = f.LC(), f.all_coeffs() result, sign = [], -1 for i, coeff in enumerate(coeffs[1:]): poly = symmetric_poly(i + 1, roots) coeff = sign(coeff/lc) result.append((poly, coeff)) sign = -sign return result
425e7dedeab507eb79b243037069615d94c3bd3d00c86ea6b767a0696cfeaaff	"""Heuristic polynomial GCD algorithm (HEUGCD). """ from __future__ import print_function, division from sympy.core.compatibility import range from .polyerrors import HeuristicGCDFailed HEU_GCD_MAX = 6 def heugcd(f, g): """ Heuristic polynomial GCD in ``Z[X]``. Given univariate polynomials ``f`` and ``g`` in ``Z[X]``, returns their GCD and cofactors, i.e. polynomials ``h``, ``cff`` and ``cfg`` such that:: h = gcd(f, g), cff = quo(f, h) and cfg = quo(g, h) The algorithm is purely heuristic which means it may fail to compute the GCD. This will be signaled by raising an exception. In this case you will need to switch to another GCD method. The algorithm computes the polynomial GCD by evaluating polynomials ``f`` and ``g`` at certain points and computing (fast) integer GCD of those evaluations. The polynomial GCD is recovered from the integer image by interpolation. The evaluation process reduces f and g variable by variable into a large integer. The final step is to verify if the interpolated polynomial is the correct GCD. This gives cofactors of the input polynomials as a side effect. Examples ======== >>> from sympy.polys.heuristicgcd import heugcd >>> from sympy.polys import ring, ZZ >>> R, x,y, = ring("x,y", ZZ) >>> f = x*2 + 2xy + y2 >>> g = x2 + xy >>> h, cff, cfg = heugcd(f, g) >>> h, cff, cfg (x + y, x + y, x) >>> cffh == f True >>> cfgh == g True References ========== .. [1] [Liao95]_ """ assert f.ring == g.ring and f.ring.domain.is_ZZ ring = f.ring x0 = ring.gens[0] domain = ring.domain gcd, f, g = f.extract_ground(g) f_norm = f.max_norm() g_norm = g.max_norm() B = domain(2min(f_norm, g_norm) + 29) x = max(min(B, 99domain.sqrt(B)), 2min(f_norm // abs(f.LC), g_norm // abs(g.LC)) + 2) for i in range(0, HEU_GCD_MAX): ff = f.evaluate(x0, x) gg = g.evaluate(x0, x) if ff and gg: if ring.ngens == 1: h, cff, cfg = domain.cofactors(ff, gg) else: h, cff, cfg = heugcd(ff, gg) h = _gcd_interpolate(h, x, ring) h = h.primitive()[1] cff_, r = f.div(h) if not r: cfg_, r = g.div(h) if not r: h = h.mul_ground(gcd) return h, cff_, cfg_ cff = _gcd_interpolate(cff, x, ring) h, r = f.div(cff) if not r: cfg_, r = g.div(h) if not r: h = h.mul_ground(gcd) return h, cff, cfg_ cfg = _gcd_interpolate(cfg, x, ring) h, r = g.div(cfg) if not r: cff_, r = f.div(h) if not r: h = h.mul_ground(gcd) return h, cff_, cfg x = 73794x * domain.sqrt(domain.sqrt(x)) // 27011 raise HeuristicGCDFailed('no luck') def _gcd_interpolate(h, x, ring): """Interpolate polynomial GCD from integer GCD. """ f, i = ring.zero, 0 # TODO: don't expose poly repr implementation details if ring.ngens == 1: while h: g = h % x if g > x // 2: g -= x h = (h - g) // x # f += X*ig if g: f[(i,)] = g i += 1 else: while h: g = h.trunc_ground(x) h = (h - g).quo_ground(x) # f += X*ig if g: for monom, coeff in g.iterterms(): f[(i,) + monom] = coeff i += 1 if f.LC < 0: return -f else: return f
b7598c0a743c419febb9a1e855976746833134875f6ad86c9445248454135ecd	"""Tools and arithmetics for monomials of distributed polynomials. """ from __future__ import print_function, division from itertools import combinations_with_replacement, product from textwrap import dedent from sympy.core import Mul, S, Tuple, sympify from sympy.core.compatibility import exec_, iterable, range from sympy.polys.polyerrors import ExactQuotientFailed from sympy.polys.polyutils import PicklableWithSlots, dict_from_expr from sympy.utilities import public @public def itermonomials(variables, max_degree, min_degree = 0): r""" Generate a set of monomials of the degree greater than or equal to `min_degree` and less than or equal to `max_degree`. Given a set of variables `V` and a min_degree `N` and a max_degree `M` generate a set of monomials of degree less than or equal to `N` and greater than or equal to `M`. The total number of monomials in commutative variables is huge and is given by the following formula if `M = 0`: .. math:: \frac{(\#V + N)!}{\#V! N!} For example if we would like to generate a dense polynomial of a total degree `N = 50` and `M = 0`, which is the worst case, in 5 variables, assuming that exponents and all of coefficients are 32-bit long and stored in an array we would need almost 80 GiB of memory! Fortunately most polynomials, that we will encounter, are sparse. Examples ======== Consider monomials in commutative variables `x` and `y` and non-commutative variables `a` and `b`:: >>> from sympy import symbols >>> from sympy.polys.monomials import itermonomials >>> from sympy.polys.orderings import monomial_key >>> from sympy.abc import x, y >>> sorted(itermonomials([x, y], 2), key=monomial_key('grlex', [y, x])) [1, x, y, x*2, xy, y2] >>> sorted(itermonomials([x, y], 3), key=monomial_key('grlex', [y, x])) [1, x, y, x2, xy, y2, x3, x2y, xy2, y3] >>> a, b = symbols('a, b', commutative=False) >>> itermonomials([a, b, x], 2) {1, a, a2, b, b2, x, x2, ab, ba, xa, xb} >>> sorted(itermonomials([x, y], 2, 1), key=monomial_key('grlex', [y, x])) [x, y, x2, xy, y*2] """ if max_degree < 0 or min_degree > max_degree: return set() if not variables or max_degree == 0: return {S(1)} # Force to list in case of passed tuple or other incompatible collection variables = list(variables) + [S(1)] if all(variable.is_commutative for variable in variables): monomials_list_comm = [] for item in combinations_with_replacement(variables, max_degree): powers = dict() for variable in variables: powers[variable] = 0 for variable in item: if variable != 1: powers[variable] += 1 if max(powers.values()) >= min_degree: monomials_list_comm.append(Mul(item)) return set(monomials_list_comm) else: monomials_list_non_comm = [] for item in product(variables, repeat=max_degree): powers = dict() for variable in variables: powers[variable] = 0 for variable in item: if variable != 1: powers[variable] += 1 if max(powers.values()) >= min_degree: monomials_list_non_comm.append(Mul(item)) return set(monomials_list_non_comm) def monomial_count(V, N): r""" Computes the number of monomials. The number of monomials is given by the following formula: .. math:: \frac{(\#V + N)!}{\#V! N!} where `N` is a total degree and `V` is a set of variables. Examples ======== >>> from sympy.polys.monomials import itermonomials, monomial_count >>> from sympy.polys.orderings import monomial_key >>> from sympy.abc import x, y >>> monomial_count(2, 2) 6 >>> M = itermonomials([x, y], 2) >>> sorted(M, key=monomial_key('grlex', [y, x])) [1, x, y, x2, xy, y2] >>> len(M) 6 """ from sympy import factorial return factorial(V + N) / factorial(V) / factorial(N) def monomial_mul(A, B): """ Multiplication of tuples representing monomials. Examples ======== Lets multiply `x3y4z` with `xy2`:: >>> from sympy.polys.monomials import monomial_mul >>> monomial_mul((3, 4, 1), (1, 2, 0)) (4, 6, 1) which gives `x4y*5z`. """ return tuple([ a + b for a, b in zip(A, B) ]) def monomial_div(A, B): """ Division of tuples representing monomials. Examples ======== Lets divide `x*3y*4z` by `xy2`:: >>> from sympy.polys.monomials import monomial_div >>> monomial_div((3, 4, 1), (1, 2, 0)) (2, 2, 1) which gives `x2y*2z`. However:: >>> monomial_div((3, 4, 1), (1, 2, 2)) is None True `xy2z2` does not divide `x3y4z`. """ C = monomial_ldiv(A, B) if all(c >= 0 for c in C): return tuple(C) else: return None def monomial_ldiv(A, B): """ Division of tuples representing monomials. Examples ======== Lets divide `x*3y*4z` by `xy2`:: >>> from sympy.polys.monomials import monomial_ldiv >>> monomial_ldiv((3, 4, 1), (1, 2, 0)) (2, 2, 1) which gives `x2y*2z`. >>> monomial_ldiv((3, 4, 1), (1, 2, 2)) (2, 2, -1) which gives `x*2y*2z*-1`. """ return tuple([ a - b for a, b in zip(A, B) ]) def monomial_pow(A, n): """Return the n-th pow of the monomial. """ return tuple([ an for a in A ]) def monomial_gcd(A, B): """ Greatest common divisor of tuples representing monomials. Examples ======== Lets compute GCD of `xy4z` and `x*3y*2`:: >>> from sympy.polys.monomials import monomial_gcd >>> monomial_gcd((1, 4, 1), (3, 2, 0)) (1, 2, 0) which gives `xy*2`. """ return tuple([ min(a, b) for a, b in zip(A, B) ]) def monomial_lcm(A, B): """ Least common multiple of tuples representing monomials. Examples ======== Lets compute LCM of `xy*4z` and `x*3y2`:: >>> from sympy.polys.monomials import monomial_lcm >>> monomial_lcm((1, 4, 1), (3, 2, 0)) (3, 4, 1) which gives `x3y4z`. """ return tuple([ max(a, b) for a, b in zip(A, B) ]) def monomial_divides(A, B): """ Does there exist a monomial X such that XA == B? Examples ======== >>> from sympy.polys.monomials import monomial_divides >>> monomial_divides((1, 2), (3, 4)) True >>> monomial_divides((1, 2), (0, 2)) False """ return all(a <= b for a, b in zip(A, B)) def monomial_max(monoms): """ Returns maximal degree for each variable in a set of monomials. Examples ======== Consider monomials `x3y*4z5`, `y5z` and `x6y*3z*9`. We wish to find out what is the maximal degree for each of `x`, `y` and `z` variables:: >>> from sympy.polys.monomials import monomial_max >>> monomial_max((3,4,5), (0,5,1), (6,3,9)) (6, 5, 9) """ M = list(monoms[0]) for N in monoms[1:]: for i, n in enumerate(N): M[i] = max(M[i], n) return tuple(M) def monomial_min(monoms): """ Returns minimal degree for each variable in a set of monomials. Examples ======== Consider monomials `x*3y*4z5`, `y5z` and `x6y*3z*9`. We wish to find out what is the minimal degree for each of `x`, `y` and `z` variables:: >>> from sympy.polys.monomials import monomial_min >>> monomial_min((3,4,5), (0,5,1), (6,3,9)) (0, 3, 1) """ M = list(monoms[0]) for N in monoms[1:]: for i, n in enumerate(N): M[i] = min(M[i], n) return tuple(M) def monomial_deg(M): """ Returns the total degree of a monomial. Examples ======== The total degree of `xy^2` is 3: >>> from sympy.polys.monomials import monomial_deg >>> monomial_deg((1, 2)) 3 """ return sum(M) def term_div(a, b, domain): """Division of two terms in over a ring/field. """ a_lm, a_lc = a b_lm, b_lc = b monom = monomial_div(a_lm, b_lm) if domain.is_Field: if monom is not None: return monom, domain.quo(a_lc, b_lc) else: return None else: if not (monom is None or a_lc % b_lc): return monom, domain.quo(a_lc, b_lc) else: return None class MonomialOps(object): """Code generator of fast monomial arithmetic functions. """ def __init__(self, ngens): self.ngens = ngens def _build(self, code, name): ns = {} exec_(code, ns) return ns[name] def _vars(self, name): return [ "%s%s" % (name, i) for i in range(self.ngens) ] def mul(self): name = "monomial_mul" template = dedent("""\ def %(name)s(A, B): (%(A)s,) = A (%(B)s,) = B return (%(AB)s,) """) A = self._vars("a") B = self._vars("b") AB = [ "%s + %s" % (a, b) for a, b in zip(A, B) ] code = template % dict(name=name, A=", ".join(A), B=", ".join(B), AB=", ".join(AB)) return self._build(code, name) def pow(self): name = "monomial_pow" template = dedent("""\ def %(name)s(A, k): (%(A)s,) = A return (%(Ak)s,) """) A = self._vars("a") Ak = [ "%sk" % a for a in A ] code = template % dict(name=name, A=", ".join(A), Ak=", ".join(Ak)) return self._build(code, name) def mulpow(self): name = "monomial_mulpow" template = dedent("""\ def %(name)s(A, B, k): (%(A)s,) = A (%(B)s,) = B return (%(ABk)s,) """) A = self._vars("a") B = self._vars("b") ABk = [ "%s + %sk" % (a, b) for a, b in zip(A, B) ] code = template % dict(name=name, A=", ".join(A), B=", ".join(B), ABk=", ".join(ABk)) return self._build(code, name) def ldiv(self): name = "monomial_ldiv" template = dedent("""\ def %(name)s(A, B): (%(A)s,) = A (%(B)s,) = B return (%(AB)s,) """) A = self._vars("a") B = self._vars("b") AB = [ "%s - %s" % (a, b) for a, b in zip(A, B) ] code = template % dict(name=name, A=", ".join(A), B=", ".join(B), AB=", ".join(AB)) return self._build(code, name) def div(self): name = "monomial_div" template = dedent("""\ def %(name)s(A, B): (%(A)s,) = A (%(B)s,) = B %(RAB)s return (%(R)s,) """) A = self._vars("a") B = self._vars("b") RAB = [ "r%(i)s = a%(i)s - b%(i)s\n if r%(i)s < 0: return None" % dict(i=i) for i in range(self.ngens) ] R = self._vars("r") code = template % dict(name=name, A=", ".join(A), B=", ".join(B), RAB="\n ".join(RAB), R=", ".join(R)) return self._build(code, name) def lcm(self): name = "monomial_lcm" template = dedent("""\ def %(name)s(A, B): (%(A)s,) = A (%(B)s,) = B return (%(AB)s,) """) A = self._vars("a") B = self._vars("b") AB = [ "%s if %s >= %s else %s" % (a, a, b, b) for a, b in zip(A, B) ] code = template % dict(name=name, A=", ".join(A), B=", ".join(B), AB=", ".join(AB)) return self._build(code, name) def gcd(self): name = "monomial_gcd" template = dedent("""\ def %(name)s(A, B): (%(A)s,) = A (%(B)s,) = B return (%(AB)s,) """) A = self._vars("a") B = self._vars("b") AB = [ "%s if %s <= %s else %s" % (a, a, b, b) for a, b in zip(A, B) ] code = template % dict(name=name, A=", ".join(A), B=", ".join(B), AB=", ".join(AB)) return self._build(code, name) @public class Monomial(PicklableWithSlots): """Class representing a monomial, i.e. a product of powers. """ __slots__ = ['exponents', 'gens'] def __init__(self, monom, gens=None): if not iterable(monom): rep, gens = dict_from_expr(sympify(monom), gens=gens) if len(rep) == 1 and list(rep.values())[0] == 1: monom = list(rep.keys())[0] else: raise ValueError("Expected a monomial got %s" % monom) self.exponents = tuple(map(int, monom)) self.gens = gens def rebuild(self, exponents, gens=None): return self.__class__(exponents, gens or self.gens) def __len__(self): return len(self.exponents) def __iter__(self): return iter(self.exponents) def __getitem__(self, item): return self.exponents[item] def __hash__(self): return hash((self.__class__.__name__, self.exponents, self.gens)) def __str__(self): if self.gens: return "".join([ "%s*%s" % (gen, exp) for gen, exp in zip(self.gens, self.exponents) ]) else: return "%s(%s)" % (self.__class__.__name__, self.exponents) def as_expr(self, gens): """Convert a monomial instance to a SymPy expression. """ gens = gens or self.gens if not gens: raise ValueError( "can't convert %s to an expression without generators" % self) return Mul([ genexp for gen, exp in zip(gens, self.exponents) ]) def __eq__(self, other): if isinstance(other, Monomial): exponents = other.exponents elif isinstance(other, (tuple, Tuple)): exponents = other else: return False return self.exponents == exponents def __ne__(self, other): return not self == other def __mul__(self, other): if isinstance(other, Monomial): exponents = other.exponents elif isinstance(other, (tuple, Tuple)): exponents = other else: return NotImplementedError return self.rebuild(monomial_mul(self.exponents, exponents)) def __div__(self, other): if isinstance(other, Monomial): exponents = other.exponents elif isinstance(other, (tuple, Tuple)): exponents = other else: return NotImplementedError result = monomial_div(self.exponents, exponents) if result is not None: return self.rebuild(result) else: raise ExactQuotientFailed(self, Monomial(other)) __floordiv__ = __truediv__ = __div__ def __pow__(self, other): n = int(other) if not n: return self.rebuild([0]len(self)) elif n > 0: exponents = self.exponents for i in range(1, n): exponents = monomial_mul(exponents, self.exponents) return self.rebuild(exponents) else: raise ValueError("a non-negative integer expected, got %s" % other) def gcd(self, other): """Greatest common divisor of monomials. """ if isinstance(other, Monomial): exponents = other.exponents elif isinstance(other, (tuple, Tuple)): exponents = other else: raise TypeError( "an instance of Monomial class expected, got %s" % other) return self.rebuild(monomial_gcd(self.exponents, exponents)) def lcm(self, other): """Least common multiple of monomials. """ if isinstance(other, Monomial): exponents = other.exponents elif isinstance(other, (tuple, Tuple)): exponents = other else: raise TypeError( "an instance of Monomial class expected, got %s" % other) return self.rebuild(monomial_lcm(self.exponents, exponents))
1fb3a7215db8af6b10d61c255ad1888c60e3c28abb7e1ac505cb43a27514acda	"""Sparse rational function fields. """ from __future__ import print_function, division from operator import add, mul, lt, le, gt, ge from sympy.core.compatibility import is_sequence, reduce, string_types from sympy.core.expr import Expr from sympy.core.mod import Mod from sympy.core.numbers import Exp1 from sympy.core.singleton import S from sympy.core.symbol import Symbol from sympy.core.sympify import CantSympify, sympify from sympy.functions.elementary.exponential import ExpBase from sympy.polys.domains.domainelement import DomainElement from sympy.polys.domains.fractionfield import FractionField from sympy.polys.domains.polynomialring import PolynomialRing from sympy.polys.constructor import construct_domain from sympy.polys.orderings import lex from sympy.polys.polyerrors import CoercionFailed from sympy.polys.polyoptions import build_options from sympy.polys.polyutils import _parallel_dict_from_expr from sympy.polys.rings import PolyElement from sympy.printing.defaults import DefaultPrinting from sympy.utilities import public from sympy.utilities.magic import pollute @public def field(symbols, domain, order=lex): """Construct new rational function field returning (field, x1, ..., xn). """ _field = FracField(symbols, domain, order) return (_field,) + _field.gens @public def xfield(symbols, domain, order=lex): """Construct new rational function field returning (field, (x1, ..., xn)). """ _field = FracField(symbols, domain, order) return (_field, _field.gens) @public def vfield(symbols, domain, order=lex): """Construct new rational function field and inject generators into global namespace. """ _field = FracField(symbols, domain, order) pollute([ sym.name for sym in _field.symbols ], _field.gens) return _field @public def sfield(exprs, symbols, options): """Construct a field deriving generators and domain from options and input expressions. Parameters ========== exprs : :class:`Expr` or sequence of :class:`Expr` (sympifiable) symbols : sequence of :class:`Symbol`/:class:`Expr` options : keyword arguments understood by :class:`Options` Examples ======== >>> from sympy.core import symbols >>> from sympy.functions import exp, log >>> from sympy.polys.fields import sfield >>> x = symbols("x") >>> K, f = sfield((xlog(x) + 4x2)exp(1/x + log(x)/3)/x2) >>> K Rational function field in x, exp(1/x), log(x), x(1/3) over ZZ with lex order >>> f (4x2(exp(1/x)) + x(exp(1/x))(log(x)))/((x(1/3))5) """ single = False if not is_sequence(exprs): exprs, single = [exprs], True exprs = list(map(sympify, exprs)) opt = build_options(symbols, options) numdens = [] for expr in exprs: numdens.extend(expr.as_numer_denom()) reps, opt = _parallel_dict_from_expr(numdens, opt) if opt.domain is None: # NOTE: this is inefficient because construct_domain() automatically # performs conversion to the target domain. It shouldn't do this. coeffs = sum([list(rep.values()) for rep in reps], []) opt.domain, _ = construct_domain(coeffs, opt=opt) _field = FracField(opt.gens, opt.domain, opt.order) fracs = [] for i in range(0, len(reps), 2): fracs.append(_field(tuple(reps[i:i+2]))) if single: return (_field, fracs[0]) else: return (_field, fracs) _field_cache = {} class FracField(DefaultPrinting): """Multivariate distributed rational function field. """ def __new__(cls, symbols, domain, order=lex): from sympy.polys.rings import PolyRing ring = PolyRing(symbols, domain, order) symbols = ring.symbols ngens = ring.ngens domain = ring.domain order = ring.order _hash_tuple = (cls.__name__, symbols, ngens, domain, order) obj = _field_cache.get(_hash_tuple) if obj is None: obj = object.__new__(cls) obj._hash_tuple = _hash_tuple obj._hash = hash(_hash_tuple) obj.ring = ring obj.dtype = type("FracElement", (FracElement,), {"field": obj}) obj.symbols = symbols obj.ngens = ngens obj.domain = domain obj.order = order obj.zero = obj.dtype(ring.zero) obj.one = obj.dtype(ring.one) obj.gens = obj._gens() for symbol, generator in zip(obj.symbols, obj.gens): if isinstance(symbol, Symbol): name = symbol.name if not hasattr(obj, name): setattr(obj, name, generator) _field_cache[_hash_tuple] = obj return obj def _gens(self): """Return a list of polynomial generators. """ return tuple([ self.dtype(gen) for gen in self.ring.gens ]) def __getnewargs__(self): return (self.symbols, self.domain, self.order) def __hash__(self): return self._hash def __eq__(self, other): return isinstance(other, FracField) and \ (self.symbols, self.ngens, self.domain, self.order) == \ (other.symbols, other.ngens, other.domain, other.order) def __ne__(self, other): return not self == other def raw_new(self, numer, denom=None): return self.dtype(numer, denom) def new(self, numer, denom=None): if denom is None: denom = self.ring.one numer, denom = numer.cancel(denom) return self.raw_new(numer, denom) def domain_new(self, element): return self.domain.convert(element) def ground_new(self, element): try: return self.new(self.ring.ground_new(element)) except CoercionFailed: domain = self.domain if not domain.is_Field and domain.has_assoc_Field: ring = self.ring ground_field = domain.get_field() element = ground_field.convert(element) numer = ring.ground_new(ground_field.numer(element)) denom = ring.ground_new(ground_field.denom(element)) return self.raw_new(numer, denom) else: raise def field_new(self, element): if isinstance(element, FracElement): if self == element.field: return element else: raise NotImplementedError("conversion") elif isinstance(element, PolyElement): denom, numer = element.clear_denoms() numer = numer.set_ring(self.ring) denom = self.ring.ground_new(denom) return self.raw_new(numer, denom) elif isinstance(element, tuple) and len(element) == 2: numer, denom = list(map(self.ring.ring_new, element)) return self.new(numer, denom) elif isinstance(element, string_types): raise NotImplementedError("parsing") elif isinstance(element, Expr): return self.from_expr(element) else: return self.ground_new(element) __call__ = field_new def _rebuild_expr(self, expr, mapping): domain = self.domain powers = tuple((gen, gen.as_base_exp()) for gen in mapping.keys() if gen.is_Pow or isinstance(gen, ExpBase)) def _rebuild(expr): generator = mapping.get(expr) if generator is not None: return generator elif expr.is_Add: return reduce(add, list(map(_rebuild, expr.args))) elif expr.is_Mul: return reduce(mul, list(map(_rebuild, expr.args))) elif expr.is_Pow or isinstance(expr, (ExpBase, Exp1)): b, e = expr.as_base_exp() # look for bgeg whose integer power may be be for gen, (bg, eg) in powers: if bg == b and Mod(e, eg) == 0: return mapping.get(gen)int(e/eg) if e.is_Integer and e is not S.One: return _rebuild(b)int(e) try: return domain.convert(expr) except CoercionFailed: if not domain.is_Field and domain.has_assoc_Field: return domain.get_field().convert(expr) else: raise return _rebuild(sympify(expr)) def from_expr(self, expr): mapping = dict(list(zip(self.symbols, self.gens))) try: frac = self._rebuild_expr(expr, mapping) except CoercionFailed: raise ValueError("expected an expression convertible to a rational function in %s, got %s" % (self, expr)) else: return self.field_new(frac) def to_domain(self): return FractionField(self) def to_ring(self): from sympy.polys.rings import PolyRing return PolyRing(self.symbols, self.domain, self.order) class FracElement(DomainElement, DefaultPrinting, CantSympify): """Element of multivariate distributed rational function field. """ def __init__(self, numer, denom=None): if denom is None: denom = self.field.ring.one elif not denom: raise ZeroDivisionError("zero denominator") self.numer = numer self.denom = denom def raw_new(f, numer, denom): return f.__class__(numer, denom) def new(f, numer, denom): return f.raw_new(numer.cancel(denom)) def to_poly(f): if f.denom != 1: raise ValueError("f.denom should be 1") return f.numer def parent(self): return self.field.to_domain() def __getnewargs__(self): return (self.field, self.numer, self.denom) _hash = None def __hash__(self): _hash = self._hash if _hash is None: self._hash = _hash = hash((self.field, self.numer, self.denom)) return _hash def copy(self): return self.raw_new(self.numer.copy(), self.denom.copy()) def set_field(self, new_field): if self.field == new_field: return self else: new_ring = new_field.ring numer = self.numer.set_ring(new_ring) denom = self.denom.set_ring(new_ring) return new_field.new(numer, denom) def as_expr(self, symbols): return self.numer.as_expr(symbols)/self.denom.as_expr(symbols) def __eq__(f, g): if isinstance(g, FracElement) and f.field == g.field: return f.numer == g.numer and f.denom == g.denom else: return f.numer == g and f.denom == f.field.ring.one def __ne__(f, g): return not f == g def __nonzero__(f): return bool(f.numer) __bool__ = __nonzero__ def sort_key(self): return (self.denom.sort_key(), self.numer.sort_key()) def _cmp(f1, f2, op): if isinstance(f2, f1.field.dtype): return op(f1.sort_key(), f2.sort_key()) else: return NotImplemented def __lt__(f1, f2): return f1._cmp(f2, lt) def __le__(f1, f2): return f1._cmp(f2, le) def __gt__(f1, f2): return f1._cmp(f2, gt) def __ge__(f1, f2): return f1._cmp(f2, ge) def __pos__(f): """Negate all coefficients in ``f``. """ return f.raw_new(f.numer, f.denom) def __neg__(f): """Negate all coefficients in ``f``. """ return f.raw_new(-f.numer, f.denom) def _extract_ground(self, element): domain = self.field.domain try: element = domain.convert(element) except CoercionFailed: if not domain.is_Field and domain.has_assoc_Field: ground_field = domain.get_field() try: element = ground_field.convert(element) except CoercionFailed: pass else: return -1, ground_field.numer(element), ground_field.denom(element) return 0, None, None else: return 1, element, None def __add__(f, g): """Add rational functions ``f`` and ``g``. """ field = f.field if not g: return f elif not f: return g elif isinstance(g, field.dtype): if f.denom == g.denom: return f.new(f.numer + g.numer, f.denom) else: return f.new(f.numerg.denom + f.denomg.numer, f.denomg.denom) elif isinstance(g, field.ring.dtype): return f.new(f.numer + f.denomg, f.denom) else: if isinstance(g, FracElement): if isinstance(field.domain, FractionField) and field.domain.field == g.field: pass elif isinstance(g.field.domain, FractionField) and g.field.domain.field == field: return g.__radd__(f) else: return NotImplemented elif isinstance(g, PolyElement): if isinstance(field.domain, PolynomialRing) and field.domain.ring == g.ring: pass else: return g.__radd__(f) return f.__radd__(g) def __radd__(f, c): if isinstance(c, f.field.ring.dtype): return f.new(f.numer + f.denomc, f.denom) op, g_numer, g_denom = f._extract_ground(c) if op == 1: return f.new(f.numer + f.denomg_numer, f.denom) elif not op: return NotImplemented else: return f.new(f.numerg_denom + f.denomg_numer, f.denomg_denom) def __sub__(f, g): """Subtract rational functions ``f`` and ``g``. """ field = f.field if not g: return f elif not f: return -g elif isinstance(g, field.dtype): if f.denom == g.denom: return f.new(f.numer - g.numer, f.denom) else: return f.new(f.numerg.denom - f.denomg.numer, f.denomg.denom) elif isinstance(g, field.ring.dtype): return f.new(f.numer - f.denomg, f.denom) else: if isinstance(g, FracElement): if isinstance(field.domain, FractionField) and field.domain.field == g.field: pass elif isinstance(g.field.domain, FractionField) and g.field.domain.field == field: return g.__rsub__(f) else: return NotImplemented elif isinstance(g, PolyElement): if isinstance(field.domain, PolynomialRing) and field.domain.ring == g.ring: pass else: return g.__rsub__(f) op, g_numer, g_denom = f._extract_ground(g) if op == 1: return f.new(f.numer - f.denomg_numer, f.denom) elif not op: return NotImplemented else: return f.new(f.numerg_denom - f.denomg_numer, f.denomg_denom) def __rsub__(f, c): if isinstance(c, f.field.ring.dtype): return f.new(-f.numer + f.denomc, f.denom) op, g_numer, g_denom = f._extract_ground(c) if op == 1: return f.new(-f.numer + f.denomg_numer, f.denom) elif not op: return NotImplemented else: return f.new(-f.numerg_denom + f.denomg_numer, f.denomg_denom) def __mul__(f, g): """Multiply rational functions ``f`` and ``g``. """ field = f.field if not f or not g: return field.zero elif isinstance(g, field.dtype): return f.new(f.numerg.numer, f.denomg.denom) elif isinstance(g, field.ring.dtype): return f.new(f.numerg, f.denom) else: if isinstance(g, FracElement): if isinstance(field.domain, FractionField) and field.domain.field == g.field: pass elif isinstance(g.field.domain, FractionField) and g.field.domain.field == field: return g.__rmul__(f) else: return NotImplemented elif isinstance(g, PolyElement): if isinstance(field.domain, PolynomialRing) and field.domain.ring == g.ring: pass else: return g.__rmul__(f) return f.__rmul__(g) def __rmul__(f, c): if isinstance(c, f.field.ring.dtype): return f.new(f.numerc, f.denom) op, g_numer, g_denom = f._extract_ground(c) if op == 1: return f.new(f.numerg_numer, f.denom) elif not op: return NotImplemented else: return f.new(f.numerg_numer, f.denomg_denom) def __truediv__(f, g): """Computes quotient of fractions ``f`` and ``g``. """ field = f.field if not g: raise ZeroDivisionError elif isinstance(g, field.dtype): return f.new(f.numerg.denom, f.denomg.numer) elif isinstance(g, field.ring.dtype): return f.new(f.numer, f.denomg) else: if isinstance(g, FracElement): if isinstance(field.domain, FractionField) and field.domain.field == g.field: pass elif isinstance(g.field.domain, FractionField) and g.field.domain.field == field: return g.__rtruediv__(f) else: return NotImplemented elif isinstance(g, PolyElement): if isinstance(field.domain, PolynomialRing) and field.domain.ring == g.ring: pass else: return g.__rtruediv__(f) op, g_numer, g_denom = f._extract_ground(g) if op == 1: return f.new(f.numer, f.denomg_numer) elif not op: return NotImplemented else: return f.new(f.numerg_denom, f.denomg_numer) __div__ = __truediv__ def __rtruediv__(f, c): if not f: raise ZeroDivisionError elif isinstance(c, f.field.ring.dtype): return f.new(f.denomc, f.numer) op, g_numer, g_denom = f._extract_ground(c) if op == 1: return f.new(f.denomg_numer, f.numer) elif not op: return NotImplemented else: return f.new(f.denomg_numer, f.numerg_denom) __rdiv__ = __rtruediv__ def __pow__(f, n): """Raise ``f`` to a non-negative power ``n``. """ if n >= 0: return f.raw_new(f.numern, f.denomn) elif not f: raise ZeroDivisionError else: return f.raw_new(f.denom-n, f.numer-n) def diff(f, x): """Computes partial derivative in ``x``. Examples ======== >>> from sympy.polys.fields import field >>> from sympy.polys.domains import ZZ >>> _, x, y, z = field("x,y,z", ZZ) >>> ((x2 + y)/(z + 1)).diff(x) 2x/(z + 1) """ x = x.to_poly() return f.new(f.numer.diff(x)f.denom - f.numerf.denom.diff(x), f.denom*2) def __call__(f, values): if 0 < len(values) <= f.field.ngens: return f.evaluate(list(zip(f.field.gens, values))) else: raise ValueError("expected at least 1 and at most %s values, got %s" % (f.field.ngens, len(values))) def evaluate(f, x, a=None): if isinstance(x, list) and a is None: x = [ (X.to_poly(), a) for X, a in x ] numer, denom = f.numer.evaluate(x), f.denom.evaluate(x) else: x = x.to_poly() numer, denom = f.numer.evaluate(x, a), f.denom.evaluate(x, a) field = numer.ring.to_field() return field.new(numer, denom) def subs(f, x, a=None): if isinstance(x, list) and a is None: x = [ (X.to_poly(), a) for X, a in x ] numer, denom = f.numer.subs(x), f.denom.subs(x) else: x = x.to_poly() numer, denom = f.numer.subs(x, a), f.denom.subs(x, a) return f.new(numer, denom) def compose(f, x, a=None): raise NotImplementedError
502ccb5cc4cb867dbf1a38d071db11137fd91d98e5ee35bdd50e33faeae0222e	"""Low-level linear systems solver. """ from __future__ import print_function, division from sympy.matrices import Matrix, zeros class RawMatrix(Matrix): _sympify = staticmethod(lambda x: x) def eqs_to_matrix(eqs, ring): """Transform from equations to matrix form. """ xs = ring.gens M = zeros(len(eqs), len(xs)+1, cls=RawMatrix) for j, e_j in enumerate(eqs): for i, x_i in enumerate(xs): M[j, i] = e_j.coeff(x_i) M[j, -1] = -e_j.coeff(1) return M def solve_lin_sys(eqs, ring, _raw=True): """Solve a system of linear equations. If ``_raw`` is False, the keys and values in the returned dictionary will be of type Expr (and the unit of the field will be removed from the keys) otherwise the low-level polys types will be returned, e.g. PolyElement: PythonRational. """ as_expr = not _raw assert ring.domain.is_Field # transform from equations to matrix form matrix = eqs_to_matrix(eqs, ring) # solve by row-reduction echelon, pivots = matrix.rref(iszerofunc=lambda x: not x, simplify=lambda x: x) # construct the returnable form of the solutions keys = ring.symbols if as_expr else ring.gens if pivots[-1] == len(keys): return None if len(pivots) == len(keys): sol = [] for s in echelon[:, -1]: a = ring.ground_new(s) if as_expr: a = a.as_expr() sol.append(a) sols = dict(zip(keys, sol)) else: sols = {} g = ring.gens _g = [[-i] for i in g] for i, p in enumerate(pivots): vect = RawMatrix(_g[p + 1:] + [[ring.one]]) v = (echelon[i, p + 1:]*vect)[0] if as_expr: v = v.as_expr() sols[keys[p]] = v return sols
01db79de387f18bda5af7c7c4e809b2d5e90573c6dfc629a8510af60530a65a7	"""Algorithms for partial fraction decomposition of rational functions. """ from __future__ import print_function, division from sympy.core import S, Add, sympify, Function, Lambda, Dummy from sympy.core.basic import preorder_traversal from sympy.core.compatibility import range from sympy.polys import Poly, RootSum, cancel, factor from sympy.polys.polyerrors import PolynomialError from sympy.polys.polyoptions import allowed_flags, set_defaults from sympy.polys.polytools import parallel_poly_from_expr from sympy.utilities import numbered_symbols, take, xthreaded, public @xthreaded @public def apart(f, x=None, full=False, options): """ Compute partial fraction decomposition of a rational function. Given a rational function ``f``, computes the partial fraction decomposition of ``f``. Two algorithms are available: One is based on the undertermined coefficients method, the other is Bronstein's full partial fraction decomposition algorithm. The undetermined coefficients method (selected by ``full=False``) uses polynomial factorization (and therefore accepts the same options as factor) for the denominator. Per default it works over the rational numbers, therefore decomposition of denominators with non-rational roots (e.g. irrational, complex roots) is not supported by default (see options of factor). Bronstein's algorithm can be selected by using ``full=True`` and allows a decomposition of denominators with non-rational roots. A human-readable result can be obtained via ``doit()`` (see examples below). Examples ======== >>> from sympy.polys.partfrac import apart >>> from sympy.abc import x, y By default, using the undetermined coefficients method: >>> apart(y/(x + 2)/(x + 1), x) -y/(x + 2) + y/(x + 1) The undetermined coefficients method does not provide a result when the denominators roots are not rational: >>> apart(y/(x2 + x + 1), x) y/(x2 + x + 1) You can choose Bronstein's algorithm by setting ``full=True``: >>> apart(y/(x2 + x + 1), x, full=True) RootSum(_w*2 + _w + 1, Lambda(_a, (-2_ay/3 - y/3)/(-_a + x))) Calling ``doit()`` yields a human-readable result: >>> apart(y/(x2 + x + 1), x, full=True).doit() (-y/3 - 2y(-1/2 - sqrt(3)I/2)/3)/(x + 1/2 + sqrt(3)I/2) + (-y/3 - 2y(-1/2 + sqrt(3)I/2)/3)/(x + 1/2 - sqrt(3)I/2) See Also ======== apart_list, assemble_partfrac_list """ allowed_flags(options, []) f = sympify(f) if f.is_Atom: return f else: P, Q = f.as_numer_denom() _options = options.copy() options = set_defaults(options, extension=True) try: (P, Q), opt = parallel_poly_from_expr((P, Q), x, options) except PolynomialError as msg: if f.is_commutative: raise PolynomialError(msg) # non-commutative if f.is_Mul: c, nc = f.args_cnc(split_1=False) nc = f.func(nc) if c: c = apart(f.func._from_args(c), x=x, full=full, *_options) return cnc else: return nc elif f.is_Add: c = [] nc = [] for i in f.args: if i.is_commutative: c.append(i) else: try: nc.append(apart(i, x=x, full=full, *_options)) except NotImplementedError: nc.append(i) return apart(f.func(c), x=x, full=full, *_options) + f.func(nc) else: reps = [] pot = preorder_traversal(f) next(pot) for e in pot: try: reps.append((e, apart(e, x=x, full=full, _options))) pot.skip() # this was handled successfully except NotImplementedError: pass return f.xreplace(dict(reps)) if P.is_multivariate: fc = f.cancel() if fc != f: return apart(fc, x=x, full=full, _options) raise NotImplementedError( "multivariate partial fraction decomposition") common, P, Q = P.cancel(Q) poly, P = P.div(Q, auto=True) P, Q = P.rat_clear_denoms(Q) if Q.degree() <= 1: partial = P/Q else: if not full: partial = apart_undetermined_coeffs(P, Q) else: partial = apart_full_decomposition(P, Q) terms = S.Zero for term in Add.make_args(partial): if term.has(RootSum): terms += term else: terms += factor(term) return common(poly.as_expr() + terms) def apart_undetermined_coeffs(P, Q): """Partial fractions via method of undetermined coefficients. """ X = numbered_symbols(cls=Dummy) partial, symbols = [], [] _, factors = Q.factor_list() for f, k in factors: n, q = f.degree(), Q for i in range(1, k + 1): coeffs, q = take(X, n), q.quo(f) partial.append((coeffs, q, f, i)) symbols.extend(coeffs) dom = Q.get_domain().inject(symbols) F = Poly(0, Q.gen, domain=dom) for i, (coeffs, q, f, k) in enumerate(partial): h = Poly(coeffs, Q.gen, domain=dom) partial[i] = (h, f, k) q = q.set_domain(dom) F += hq system, result = [], S(0) for (k,), coeff in F.terms(): system.append(coeff - P.nth(k)) from sympy.solvers import solve solution = solve(system, symbols) for h, f, k in partial: h = h.as_expr().subs(solution) result += h/f.as_expr()k return result def apart_full_decomposition(P, Q): """ Bronstein's full partial fraction decomposition algorithm. Given a univariate rational function ``f``, performing only GCD operations over the algebraic closure of the initial ground domain of definition, compute full partial fraction decomposition with fractions having linear denominators. Note that no factorization of the initial denominator of ``f`` is performed. The final decomposition is formed in terms of a sum of :class:`RootSum` instances. References ========== .. [1] [Bronstein93]_ """ return assemble_partfrac_list(apart_list(P/Q, P.gens[0])) @public def apart_list(f, x=None, dummies=None, options): """ Compute partial fraction decomposition of a rational function and return the result in structured form. Given a rational function ``f`` compute the partial fraction decomposition of ``f``. Only Bronstein's full partial fraction decomposition algorithm is supported by this method. The return value is highly structured and perfectly suited for further algorithmic treatment rather than being human-readable. The function returns a tuple holding three elements: The first item is the common coefficient, free of the variable `x` used for decomposition. (It is an element of the base field `K`.) * The second item is the polynomial part of the decomposition. This can be the zero polynomial. (It is an element of `K[x]`.) * The third part itself is a list of quadruples. Each quadruple has the following elements in this order: - The (not necessarily irreducible) polynomial `D` whose roots `w_i` appear in the linear denominator of a bunch of related fraction terms. (This item can also be a list of explicit roots. However, at the moment ``apart_list`` never returns a result this way, but the related ``assemble_partfrac_list`` function accepts this format as input.) - The numerator of the fraction, written as a function of the root `w` - The linear denominator of the fraction excluding its power exponent, written as a function of the root `w`. - The power to which the denominator has to be raised. On can always rebuild a plain expression by using the function ``assemble_partfrac_list``. Examples ======== A first example: >>> from sympy.polys.partfrac import apart_list, assemble_partfrac_list >>> from sympy.abc import x, t >>> f = (2x3 - 2x) / (x*2 - 2x + 1) >>> pfd = apart_list(f) >>> pfd (1, Poly(2x + 4, x, domain='ZZ'), [(Poly(_w - 1, _w, domain='ZZ'), Lambda(_a, 4), Lambda(_a, -_a + x), 1)]) >>> assemble_partfrac_list(pfd) 2x + 4 + 4/(x - 1) Second example: >>> f = (-2x - 2x*2) / (3x*2 - 6x) >>> pfd = apart_list(f) >>> pfd (-1, Poly(2/3, x, domain='QQ'), [(Poly(_w - 2, _w, domain='ZZ'), Lambda(_a, 2), Lambda(_a, -_a + x), 1)]) >>> assemble_partfrac_list(pfd) -2/3 - 2/(x - 2) Another example, showing symbolic parameters: >>> pfd = apart_list(t/(x2 + x + t), x) >>> pfd (1, Poly(0, x, domain='ZZ[t]'), [(Poly(_w2 + _w + t, _w, domain='ZZ[t]'), Lambda(_a, -2_at/(4t - 1) - t/(4t - 1)), Lambda(_a, -_a + x), 1)]) >>> assemble_partfrac_list(pfd) RootSum(_w*2 + _w + t, Lambda(_a, (-2_at/(4t - 1) - t/(4t - 1))/(-_a + x))) This example is taken from Bronstein's original paper: >>> f = 36 / (x5 - 2x*4 - 2x*3 + 4x2 + x - 2) >>> pfd = apart_list(f) >>> pfd (1, Poly(0, x, domain='ZZ'), [(Poly(_w - 2, _w, domain='ZZ'), Lambda(_a, 4), Lambda(_a, -_a + x), 1), (Poly(_w2 - 1, _w, domain='ZZ'), Lambda(_a, -3_a - 6), Lambda(_a, -_a + x), 2), (Poly(_w + 1, _w, domain='ZZ'), Lambda(_a, -4), Lambda(_a, -_a + x), 1)]) >>> assemble_partfrac_list(pfd) -4/(x + 1) - 3/(x + 1)2 - 9/(x - 1)2 + 4/(x - 2) See also ======== apart, assemble_partfrac_list References ========== .. [1] [Bronstein93]_ """ allowed_flags(options, []) f = sympify(f) if f.is_Atom: return f else: P, Q = f.as_numer_denom() options = set_defaults(options, extension=True) (P, Q), opt = parallel_poly_from_expr((P, Q), x, options) if P.is_multivariate: raise NotImplementedError( "multivariate partial fraction decomposition") common, P, Q = P.cancel(Q) poly, P = P.div(Q, auto=True) P, Q = P.rat_clear_denoms(Q) polypart = poly if dummies is None: def dummies(name): d = Dummy(name) while True: yield d dummies = dummies("w") rationalpart = apart_list_full_decomposition(P, Q, dummies) return (common, polypart, rationalpart) def apart_list_full_decomposition(P, Q, dummygen): """ Bronstein's full partial fraction decomposition algorithm. Given a univariate rational function ``f``, performing only GCD operations over the algebraic closure of the initial ground domain of definition, compute full partial fraction decomposition with fractions having linear denominators. Note that no factorization of the initial denominator of ``f`` is performed. The final decomposition is formed in terms of a sum of :class:`RootSum` instances. References ========== .. [1] [Bronstein93]_ """ f, x, U = P/Q, P.gen, [] u = Function('u')(x) a = Dummy('a') partial = [] for d, n in Q.sqf_list_include(all=True): b = d.as_expr() U += [ u.diff(x, n - 1) ] h = cancel(fbn) / un H, subs = [h], [] for j in range(1, n): H += [ H[-1].diff(x) / j ] for j in range(1, n + 1): subs += [ (U[j - 1], b.diff(x, j) / j) ] for j in range(0, n): P, Q = cancel(H[j]).as_numer_denom() for i in range(0, j + 1): P = P.subs(subs[j - i]) Q = Q.subs(subs[0]) P = Poly(P, x) Q = Poly(Q, x) G = P.gcd(d) D = d.quo(G) B, g = Q.half_gcdex(D) b = (P * B.quo(g)).rem(D) Dw = D.subs(x, next(dummygen)) numer = Lambda(a, b.as_expr().subs(x, a)) denom = Lambda(a, (x - a)) exponent = n-j partial.append((Dw, numer, denom, exponent)) return partial @public def assemble_partfrac_list(partial_list): r"""Reassemble a full partial fraction decomposition from a structured result obtained by the function ``apart_list``. Examples ======== This example is taken from Bronstein's original paper: >>> from sympy.polys.partfrac import apart_list, assemble_partfrac_list >>> from sympy.abc import x, y >>> f = 36 / (x*5 - 2x*4 - 2x*3 + 4x2 + x - 2) >>> pfd = apart_list(f) >>> pfd (1, Poly(0, x, domain='ZZ'), [(Poly(_w - 2, _w, domain='ZZ'), Lambda(_a, 4), Lambda(_a, -_a + x), 1), (Poly(_w2 - 1, _w, domain='ZZ'), Lambda(_a, -3_a - 6), Lambda(_a, -_a + x), 2), (Poly(_w + 1, _w, domain='ZZ'), Lambda(_a, -4), Lambda(_a, -_a + x), 1)]) >>> assemble_partfrac_list(pfd) -4/(x + 1) - 3/(x + 1)2 - 9/(x - 1)2 + 4/(x - 2) If we happen to know some roots we can provide them easily inside the structure: >>> pfd = apart_list(2/(x2-2)) >>> pfd (1, Poly(0, x, domain='ZZ'), [(Poly(_w2 - 2, _w, domain='ZZ'), Lambda(_a, _a/2), Lambda(_a, -_a + x), 1)]) >>> pfda = assemble_partfrac_list(pfd) >>> pfda RootSum(_w2 - 2, Lambda(_a, _a/(-_a + x)))/2 >>> pfda.doit() -sqrt(2)/(2(x + sqrt(2))) + sqrt(2)/(2(x - sqrt(2))) >>> from sympy import Dummy, Poly, Lambda, sqrt >>> a = Dummy("a") >>> pfd = (1, Poly(0, x, domain='ZZ'), [([sqrt(2),-sqrt(2)], Lambda(a, a/2), Lambda(a, -a + x), 1)]) >>> assemble_partfrac_list(pfd) -sqrt(2)/(2(x + sqrt(2))) + sqrt(2)/(2(x - sqrt(2))) See Also ======== apart, apart_list """ # Common factor common = partial_list[0] # Polynomial part polypart = partial_list[1] pfd = polypart.as_expr() # Rational parts for r, nf, df, ex in partial_list[2]: if isinstance(r, Poly): # Assemble in case the roots are given implicitly by a polynomials an, nu = nf.variables, nf.expr ad, de = df.variables, df.expr # Hack to make dummies equal because Lambda created new Dummies de = de.subs(ad[0], an[0]) func = Lambda(an, nu/deex) pfd += RootSum(r, func, auto=False, quadratic=False) else: # Assemble in case the roots are given explicitly by a list of algebraic numbers for root in r: pfd += nf(root)/df(root)ex return commonpfd
a017f8df533bd2a0c2fd84521f42b5c3bc5e69ba5e33a9a5dedac39e0a940350	"""Real and complex root isolation and refinement algorithms. """ from __future__ import print_function, division from sympy.core.compatibility import range from sympy.polys.densearith import ( dup_neg, dup_rshift, dup_rem) from sympy.polys.densebasic import ( dup_LC, dup_TC, dup_degree, dup_strip, dup_reverse, dup_convert, dup_terms_gcd) from sympy.polys.densetools import ( dup_clear_denoms, dup_mirror, dup_scale, dup_shift, dup_transform, dup_diff, dup_eval, dmp_eval_in, dup_sign_variations, dup_real_imag) from sympy.polys.factortools import ( dup_factor_list) from sympy.polys.polyerrors import ( RefinementFailed, DomainError) from sympy.polys.sqfreetools import ( dup_sqf_part, dup_sqf_list) def dup_sturm(f, K): """ Computes the Sturm sequence of ``f`` in ``F[x]``. Given a univariate, square-free polynomial ``f(x)`` returns the associated Sturm sequence ``f_0(x), ..., f_n(x)`` defined by:: f_0(x), f_1(x) = f(x), f'(x) f_n = -rem(f_{n-2}(x), f_{n-1}(x)) Examples ======== >>> from sympy.polys import ring, QQ >>> R, x = ring("x", QQ) >>> R.dup_sturm(x*3 - 2x2 + x - 3) [x3 - 2x2 + x - 3, 3x*2 - 4x + 1, 2/9x + 25/9, -2079/4] References ========== .. [1] [Davenport88]_ """ if not K.is_Field: raise DomainError("can't compute Sturm sequence over %s" % K) f = dup_sqf_part(f, K) sturm = [f, dup_diff(f, 1, K)] while sturm[-1]: s = dup_rem(sturm[-2], sturm[-1], K) sturm.append(dup_neg(s, K)) return sturm[:-1] def dup_root_upper_bound(f, K): """Compute the LMQ upper bound for the positive roots of `f`; LMQ (Local Max Quadratic) was developed by Akritas-Strzebonski-Vigklas. References ========== .. [1] Alkiviadis G. Akritas: "Linear and Quadratic Complexity Bounds on the Values of the Positive Roots of Polynomials" Journal of Universal Computer Science, Vol. 15, No. 3, 523-537, 2009. """ n, P = len(f), [] t = n [K.one] if dup_LC(f, K) < 0: f = dup_neg(f, K) f = list(reversed(f)) for i in range(0, n): if f[i] >= 0: continue a, QL = K.log(-f[i], 2), [] for j in range(i + 1, n): if f[j] <= 0: continue q = t[j] + a - K.log(f[j], 2) QL.append([q // (j - i) , j]) if not QL: continue q = min(QL) t[q[1]] = t[q[1]] + 1 P.append(q[0]) if not P: return None else: return K.get_field()(2)*(max(P) + 1) def dup_root_lower_bound(f, K): """Compute the LMQ lower bound for the positive roots of `f`; LMQ (Local Max Quadratic) was developed by Akritas-Strzebonski-Vigklas. References ========== .. [1] Alkiviadis G. Akritas: "Linear and Quadratic Complexity Bounds on the Values of the Positive Roots of Polynomials" Journal of Universal Computer Science, Vol. 15, No. 3, 523-537, 2009. """ bound = dup_root_upper_bound(dup_reverse(f), K) if bound is not None: return 1/bound else: return None def _mobius_from_interval(I, field): """Convert an open interval to a Mobius transform. """ s, t = I a, c = field.numer(s), field.denom(s) b, d = field.numer(t), field.denom(t) return a, b, c, d def _mobius_to_interval(M, field): """Convert a Mobius transform to an open interval. """ a, b, c, d = M s, t = field(a, c), field(b, d) if s <= t: return (s, t) else: return (t, s) def dup_step_refine_real_root(f, M, K, fast=False): """One step of positive real root refinement algorithm. """ a, b, c, d = M if a == b and c == d: return f, (a, b, c, d) A = dup_root_lower_bound(f, K) if A is not None: A = K(int(A)) else: A = K.zero if fast and A > 16: f = dup_scale(f, A, K) a, c, A = Aa, Ac, K.one if A >= K.one: f = dup_shift(f, A, K) b, d = Aa + b, Ac + d if not dup_eval(f, K.zero, K): return f, (b, b, d, d) f, g = dup_shift(f, K.one, K), f a1, b1, c1, d1 = a, a + b, c, c + d if not dup_eval(f, K.zero, K): return f, (b1, b1, d1, d1) k = dup_sign_variations(f, K) if k == 1: a, b, c, d = a1, b1, c1, d1 else: f = dup_shift(dup_reverse(g), K.one, K) if not dup_eval(f, K.zero, K): f = dup_rshift(f, 1, K) a, b, c, d = b, a + b, d, c + d return f, (a, b, c, d) def dup_inner_refine_real_root(f, M, K, eps=None, steps=None, disjoint=None, fast=False, mobius=False): """Refine a positive root of `f` given a Mobius transform or an interval. """ F = K.get_field() if len(M) == 2: a, b, c, d = _mobius_from_interval(M, F) else: a, b, c, d = M while not c: f, (a, b, c, d) = dup_step_refine_real_root(f, (a, b, c, d), K, fast=fast) if eps is not None and steps is not None: for i in range(0, steps): if abs(F(a, c) - F(b, d)) >= eps: f, (a, b, c, d) = dup_step_refine_real_root(f, (a, b, c, d), K, fast=fast) else: break else: if eps is not None: while abs(F(a, c) - F(b, d)) >= eps: f, (a, b, c, d) = dup_step_refine_real_root(f, (a, b, c, d), K, fast=fast) if steps is not None: for i in range(0, steps): f, (a, b, c, d) = dup_step_refine_real_root(f, (a, b, c, d), K, fast=fast) if disjoint is not None: while True: u, v = _mobius_to_interval((a, b, c, d), F) if v <= disjoint or disjoint <= u: break else: f, (a, b, c, d) = dup_step_refine_real_root(f, (a, b, c, d), K, fast=fast) if not mobius: return _mobius_to_interval((a, b, c, d), F) else: return f, (a, b, c, d) def dup_outer_refine_real_root(f, s, t, K, eps=None, steps=None, disjoint=None, fast=False): """Refine a positive root of `f` given an interval `(s, t)`. """ a, b, c, d = _mobius_from_interval((s, t), K.get_field()) f = dup_transform(f, dup_strip([a, b]), dup_strip([c, d]), K) if dup_sign_variations(f, K) != 1: raise RefinementFailed("there should be exactly one root in (%s, %s) interval" % (s, t)) return dup_inner_refine_real_root(f, (a, b, c, d), K, eps=eps, steps=steps, disjoint=disjoint, fast=fast) def dup_refine_real_root(f, s, t, K, eps=None, steps=None, disjoint=None, fast=False): """Refine real root's approximating interval to the given precision. """ if K.is_QQ: (_, f), K = dup_clear_denoms(f, K, convert=True), K.get_ring() elif not K.is_ZZ: raise DomainError("real root refinement not supported over %s" % K) if s == t: return (s, t) if s > t: s, t = t, s negative = False if s < 0: if t <= 0: f, s, t, negative = dup_mirror(f, K), -t, -s, True else: raise ValueError("can't refine a real root in (%s, %s)" % (s, t)) if negative and disjoint is not None: if disjoint < 0: disjoint = -disjoint else: disjoint = None s, t = dup_outer_refine_real_root( f, s, t, K, eps=eps, steps=steps, disjoint=disjoint, fast=fast) if negative: return (-t, -s) else: return ( s, t) def dup_inner_isolate_real_roots(f, K, eps=None, fast=False): """Internal function for isolation positive roots up to given precision. References ========== 1. Alkiviadis G. Akritas and Adam W. Strzebonski: A Comparative Study of Two Real Root Isolation Methods . Nonlinear Analysis: Modelling and Control, Vol. 10, No. 4, 297-304, 2005. 2. Alkiviadis G. Akritas, Adam W. Strzebonski and Panagiotis S. Vigklas: Improving the Performance of the Continued Fractions Method Using new Bounds of Positive Roots. Nonlinear Analysis: Modelling and Control, Vol. 13, No. 3, 265-279, 2008. """ a, b, c, d = K.one, K.zero, K.zero, K.one k = dup_sign_variations(f, K) if k == 0: return [] if k == 1: roots = [dup_inner_refine_real_root( f, (a, b, c, d), K, eps=eps, fast=fast, mobius=True)] else: roots, stack = [], [(a, b, c, d, f, k)] while stack: a, b, c, d, f, k = stack.pop() A = dup_root_lower_bound(f, K) if A is not None: A = K(int(A)) else: A = K.zero if fast and A > 16: f = dup_scale(f, A, K) a, c, A = Aa, Ac, K.one if A >= K.one: f = dup_shift(f, A, K) b, d = Aa + b, Ac + d if not dup_TC(f, K): roots.append((f, (b, b, d, d))) f = dup_rshift(f, 1, K) k = dup_sign_variations(f, K) if k == 0: continue if k == 1: roots.append(dup_inner_refine_real_root( f, (a, b, c, d), K, eps=eps, fast=fast, mobius=True)) continue f1 = dup_shift(f, K.one, K) a1, b1, c1, d1, r = a, a + b, c, c + d, 0 if not dup_TC(f1, K): roots.append((f1, (b1, b1, d1, d1))) f1, r = dup_rshift(f1, 1, K), 1 k1 = dup_sign_variations(f1, K) k2 = k - k1 - r a2, b2, c2, d2 = b, a + b, d, c + d if k2 > 1: f2 = dup_shift(dup_reverse(f), K.one, K) if not dup_TC(f2, K): f2 = dup_rshift(f2, 1, K) k2 = dup_sign_variations(f2, K) else: f2 = None if k1 < k2: a1, a2, b1, b2 = a2, a1, b2, b1 c1, c2, d1, d2 = c2, c1, d2, d1 f1, f2, k1, k2 = f2, f1, k2, k1 if not k1: continue if f1 is None: f1 = dup_shift(dup_reverse(f), K.one, K) if not dup_TC(f1, K): f1 = dup_rshift(f1, 1, K) if k1 == 1: roots.append(dup_inner_refine_real_root( f1, (a1, b1, c1, d1), K, eps=eps, fast=fast, mobius=True)) else: stack.append((a1, b1, c1, d1, f1, k1)) if not k2: continue if f2 is None: f2 = dup_shift(dup_reverse(f), K.one, K) if not dup_TC(f2, K): f2 = dup_rshift(f2, 1, K) if k2 == 1: roots.append(dup_inner_refine_real_root( f2, (a2, b2, c2, d2), K, eps=eps, fast=fast, mobius=True)) else: stack.append((a2, b2, c2, d2, f2, k2)) return roots def _discard_if_outside_interval(f, M, inf, sup, K, negative, fast, mobius): """Discard an isolating interval if outside ``(inf, sup)``. """ F = K.get_field() while True: u, v = _mobius_to_interval(M, F) if negative: u, v = -v, -u if (inf is None or u >= inf) and (sup is None or v <= sup): if not mobius: return u, v else: return f, M elif (sup is not None and u > sup) or (inf is not None and v < inf): return None else: f, M = dup_step_refine_real_root(f, M, K, fast=fast) def dup_inner_isolate_positive_roots(f, K, eps=None, inf=None, sup=None, fast=False, mobius=False): """Iteratively compute disjoint positive root isolation intervals. """ if sup is not None and sup < 0: return [] roots = dup_inner_isolate_real_roots(f, K, eps=eps, fast=fast) F, results = K.get_field(), [] if inf is not None or sup is not None: for f, M in roots: result = _discard_if_outside_interval(f, M, inf, sup, K, False, fast, mobius) if result is not None: results.append(result) elif not mobius: for f, M in roots: u, v = _mobius_to_interval(M, F) results.append((u, v)) else: results = roots return results def dup_inner_isolate_negative_roots(f, K, inf=None, sup=None, eps=None, fast=False, mobius=False): """Iteratively compute disjoint negative root isolation intervals. """ if inf is not None and inf >= 0: return [] roots = dup_inner_isolate_real_roots(dup_mirror(f, K), K, eps=eps, fast=fast) F, results = K.get_field(), [] if inf is not None or sup is not None: for f, M in roots: result = _discard_if_outside_interval(f, M, inf, sup, K, True, fast, mobius) if result is not None: results.append(result) elif not mobius: for f, M in roots: u, v = _mobius_to_interval(M, F) results.append((-v, -u)) else: results = roots return results def _isolate_zero(f, K, inf, sup, basis=False, sqf=False): """Handle special case of CF algorithm when ``f`` is homogeneous. """ j, f = dup_terms_gcd(f, K) if j > 0: F = K.get_field() if (inf is None or inf <= 0) and (sup is None or 0 <= sup): if not sqf: if not basis: return [((F.zero, F.zero), j)], f else: return [((F.zero, F.zero), j, [K.one, K.zero])], f else: return [(F.zero, F.zero)], f return [], f def dup_isolate_real_roots_sqf(f, K, eps=None, inf=None, sup=None, fast=False, blackbox=False): """Isolate real roots of a square-free polynomial using the Vincent-Akritas-Strzebonski (VAS) CF approach. References ========== .. [1] Alkiviadis G. Akritas and Adam W. Strzebonski: A Comparative Study of Two Real Root Isolation Methods. Nonlinear Analysis: Modelling and Control, Vol. 10, No. 4, 297-304, 2005. .. [2] Alkiviadis G. Akritas, Adam W. Strzebonski and Panagiotis S. Vigklas: Improving the Performance of the Continued Fractions Method Using New Bounds of Positive Roots. Nonlinear Analysis: Modelling and Control, Vol. 13, No. 3, 265-279, 2008. """ if K.is_QQ: (_, f), K = dup_clear_denoms(f, K, convert=True), K.get_ring() elif not K.is_ZZ: raise DomainError("isolation of real roots not supported over %s" % K) if dup_degree(f) <= 0: return [] I_zero, f = _isolate_zero(f, K, inf, sup, basis=False, sqf=True) I_neg = dup_inner_isolate_negative_roots(f, K, eps=eps, inf=inf, sup=sup, fast=fast) I_pos = dup_inner_isolate_positive_roots(f, K, eps=eps, inf=inf, sup=sup, fast=fast) roots = sorted(I_neg + I_zero + I_pos) if not blackbox: return roots else: return [ RealInterval((a, b), f, K) for (a, b) in roots ] def dup_isolate_real_roots(f, K, eps=None, inf=None, sup=None, basis=False, fast=False): """Isolate real roots using Vincent-Akritas-Strzebonski (VAS) continued fractions approach. References ========== .. [1] Alkiviadis G. Akritas and Adam W. Strzebonski: A Comparative Study of Two Real Root Isolation Methods. Nonlinear Analysis: Modelling and Control, Vol. 10, No. 4, 297-304, 2005. .. [2] Alkiviadis G. Akritas, Adam W. Strzebonski and Panagiotis S. Vigklas: Improving the Performance of the Continued Fractions Method Using New Bounds of Positive Roots. Nonlinear Analysis: Modelling and Control, Vol. 13, No. 3, 265-279, 2008. """ if K.is_QQ: (_, f), K = dup_clear_denoms(f, K, convert=True), K.get_ring() elif not K.is_ZZ: raise DomainError("isolation of real roots not supported over %s" % K) if dup_degree(f) <= 0: return [] I_zero, f = _isolate_zero(f, K, inf, sup, basis=basis, sqf=False) _, factors = dup_sqf_list(f, K) if len(factors) == 1: ((f, k),) = factors I_neg = dup_inner_isolate_negative_roots(f, K, eps=eps, inf=inf, sup=sup, fast=fast) I_pos = dup_inner_isolate_positive_roots(f, K, eps=eps, inf=inf, sup=sup, fast=fast) I_neg = [ ((u, v), k) for u, v in I_neg ] I_pos = [ ((u, v), k) for u, v in I_pos ] else: I_neg, I_pos = _real_isolate_and_disjoin(factors, K, eps=eps, inf=inf, sup=sup, basis=basis, fast=fast) return sorted(I_neg + I_zero + I_pos) def dup_isolate_real_roots_list(polys, K, eps=None, inf=None, sup=None, strict=False, basis=False, fast=False): """Isolate real roots of a list of square-free polynomial using Vincent-Akritas-Strzebonski (VAS) CF approach. References ========== .. [1] Alkiviadis G. Akritas and Adam W. Strzebonski: A Comparative Study of Two Real Root Isolation Methods. Nonlinear Analysis: Modelling and Control, Vol. 10, No. 4, 297-304, 2005. .. [2] Alkiviadis G. Akritas, Adam W. Strzebonski and Panagiotis S. Vigklas: Improving the Performance of the Continued Fractions Method Using New Bounds of Positive Roots. Nonlinear Analysis: Modelling and Control, Vol. 13, No. 3, 265-279, 2008. """ if K.is_QQ: K, F, polys = K.get_ring(), K, polys[:] for i, p in enumerate(polys): polys[i] = dup_clear_denoms(p, F, K, convert=True)[1] elif not K.is_ZZ: raise DomainError("isolation of real roots not supported over %s" % K) zeros, factors_dict = False, {} if (inf is None or inf <= 0) and (sup is None or 0 <= sup): zeros, zero_indices = True, {} for i, p in enumerate(polys): j, p = dup_terms_gcd(p, K) if zeros and j > 0: zero_indices[i] = j for f, k in dup_factor_list(p, K)[1]: f = tuple(f) if f not in factors_dict: factors_dict[f] = {i: k} else: factors_dict[f][i] = k factors_list = [] for f, indices in factors_dict.items(): factors_list.append((list(f), indices)) I_neg, I_pos = _real_isolate_and_disjoin(factors_list, K, eps=eps, inf=inf, sup=sup, strict=strict, basis=basis, fast=fast) F = K.get_field() if not zeros or not zero_indices: I_zero = [] else: if not basis: I_zero = [((F.zero, F.zero), zero_indices)] else: I_zero = [((F.zero, F.zero), zero_indices, [K.one, K.zero])] return sorted(I_neg + I_zero + I_pos) def _disjoint_p(M, N, strict=False): """Check if Mobius transforms define disjoint intervals. """ a1, b1, c1, d1 = M a2, b2, c2, d2 = N a1d1, b1c1 = a1d1, b1c1 a2d2, b2c2 = a2d2, b2c2 if a1d1 == b1c1 and a2d2 == b2c2: return True if a1d1 > b1c1: a1, c1, b1, d1 = b1, d1, a1, c1 if a2d2 > b2c2: a2, c2, b2, d2 = b2, d2, a2, c2 if not strict: return a2d1 >= c2b1 or b2c1 <= d2a1 else: return a2d1 > c2b1 or b2c1 < d2a1 def _real_isolate_and_disjoin(factors, K, eps=None, inf=None, sup=None, strict=False, basis=False, fast=False): """Isolate real roots of a list of polynomials and disjoin intervals. """ I_pos, I_neg = [], [] for i, (f, k) in enumerate(factors): for F, M in dup_inner_isolate_positive_roots(f, K, eps=eps, inf=inf, sup=sup, fast=fast, mobius=True): I_pos.append((F, M, k, f)) for G, N in dup_inner_isolate_negative_roots(f, K, eps=eps, inf=inf, sup=sup, fast=fast, mobius=True): I_neg.append((G, N, k, f)) for i, (f, M, k, F) in enumerate(I_pos): for j, (g, N, m, G) in enumerate(I_pos[i + 1:]): while not _disjoint_p(M, N, strict=strict): f, M = dup_inner_refine_real_root(f, M, K, steps=1, fast=fast, mobius=True) g, N = dup_inner_refine_real_root(g, N, K, steps=1, fast=fast, mobius=True) I_pos[i + j + 1] = (g, N, m, G) I_pos[i] = (f, M, k, F) for i, (f, M, k, F) in enumerate(I_neg): for j, (g, N, m, G) in enumerate(I_neg[i + 1:]): while not _disjoint_p(M, N, strict=strict): f, M = dup_inner_refine_real_root(f, M, K, steps=1, fast=fast, mobius=True) g, N = dup_inner_refine_real_root(g, N, K, steps=1, fast=fast, mobius=True) I_neg[i + j + 1] = (g, N, m, G) I_neg[i] = (f, M, k, F) if strict: for i, (f, M, k, F) in enumerate(I_neg): if not M[0]: while not M[0]: f, M = dup_inner_refine_real_root(f, M, K, steps=1, fast=fast, mobius=True) I_neg[i] = (f, M, k, F) break for j, (g, N, m, G) in enumerate(I_pos): if not N[0]: while not N[0]: g, N = dup_inner_refine_real_root(g, N, K, steps=1, fast=fast, mobius=True) I_pos[j] = (g, N, m, G) break field = K.get_field() I_neg = [ (_mobius_to_interval(M, field), k, f) for (_, M, k, f) in I_neg ] I_pos = [ (_mobius_to_interval(M, field), k, f) for (_, M, k, f) in I_pos ] if not basis: I_neg = [ ((-v, -u), k) for ((u, v), k, _) in I_neg ] I_pos = [ (( u, v), k) for ((u, v), k, _) in I_pos ] else: I_neg = [ ((-v, -u), k, f) for ((u, v), k, f) in I_neg ] I_pos = [ (( u, v), k, f) for ((u, v), k, f) in I_pos ] return I_neg, I_pos def dup_count_real_roots(f, K, inf=None, sup=None): """Returns the number of distinct real roots of ``f`` in ``[inf, sup]``. """ if dup_degree(f) <= 0: return 0 if not K.is_Field: R, K = K, K.get_field() f = dup_convert(f, R, K) sturm = dup_sturm(f, K) if inf is None: signs_inf = dup_sign_variations([ dup_LC(s, K)(-1)*dup_degree(s) for s in sturm ], K) else: signs_inf = dup_sign_variations([ dup_eval(s, inf, K) for s in sturm ], K) if sup is None: signs_sup = dup_sign_variations([ dup_LC(s, K) for s in sturm ], K) else: signs_sup = dup_sign_variations([ dup_eval(s, sup, K) for s in sturm ], K) count = abs(signs_inf - signs_sup) if inf is not None and not dup_eval(f, inf, K): count += 1 return count OO = 'OO' # Origin of (re, im) coordinate system Q1 = 'Q1' # Quadrant #1 (++): re > 0 and im > 0 Q2 = 'Q2' # Quadrant #2 (-+): re < 0 and im > 0 Q3 = 'Q3' # Quadrant #3 (--): re < 0 and im < 0 Q4 = 'Q4' # Quadrant #4 (+-): re > 0 and im < 0 A1 = 'A1' # Axis #1 (+0): re > 0 and im = 0 A2 = 'A2' # Axis #2 (0+): re = 0 and im > 0 A3 = 'A3' # Axis #3 (-0): re < 0 and im = 0 A4 = 'A4' # Axis #4 (0-): re = 0 and im < 0 _rules_simple = { # Q --> Q (same) => no change (Q1, Q1): 0, (Q2, Q2): 0, (Q3, Q3): 0, (Q4, Q4): 0, # A -- CCW --> Q => +1/4 (CCW) (A1, Q1): 1, (A2, Q2): 1, (A3, Q3): 1, (A4, Q4): 1, # A -- CW --> Q => -1/4 (CCW) (A1, Q4): 2, (A2, Q1): 2, (A3, Q2): 2, (A4, Q3): 2, # Q -- CCW --> A => +1/4 (CCW) (Q1, A2): 3, (Q2, A3): 3, (Q3, A4): 3, (Q4, A1): 3, # Q -- CW --> A => -1/4 (CCW) (Q1, A1): 4, (Q2, A2): 4, (Q3, A3): 4, (Q4, A4): 4, # Q -- CCW --> Q => +1/2 (CCW) (Q1, Q2): +5, (Q2, Q3): +5, (Q3, Q4): +5, (Q4, Q1): +5, # Q -- CW --> Q => -1/2 (CW) (Q1, Q4): -5, (Q2, Q1): -5, (Q3, Q2): -5, (Q4, Q3): -5, } _rules_ambiguous = { # A -- CCW --> Q => { +1/4 (CCW), -9/4 (CW) } (A1, OO, Q1): -1, (A2, OO, Q2): -1, (A3, OO, Q3): -1, (A4, OO, Q4): -1, # A -- CW --> Q => { -1/4 (CCW), +7/4 (CW) } (A1, OO, Q4): -2, (A2, OO, Q1): -2, (A3, OO, Q2): -2, (A4, OO, Q3): -2, # Q -- CCW --> A => { +1/4 (CCW), -9/4 (CW) } (Q1, OO, A2): -3, (Q2, OO, A3): -3, (Q3, OO, A4): -3, (Q4, OO, A1): -3, # Q -- CW --> A => { -1/4 (CCW), +7/4 (CW) } (Q1, OO, A1): -4, (Q2, OO, A2): -4, (Q3, OO, A3): -4, (Q4, OO, A4): -4, # A -- OO --> A => { +1 (CCW), -1 (CW) } (A1, A3): 7, (A2, A4): 7, (A3, A1): 7, (A4, A2): 7, (A1, OO, A3): 7, (A2, OO, A4): 7, (A3, OO, A1): 7, (A4, OO, A2): 7, # Q -- DIA --> Q => { +1 (CCW), -1 (CW) } (Q1, Q3): 8, (Q2, Q4): 8, (Q3, Q1): 8, (Q4, Q2): 8, (Q1, OO, Q3): 8, (Q2, OO, Q4): 8, (Q3, OO, Q1): 8, (Q4, OO, Q2): 8, # A --- R ---> A => { +1/2 (CCW), -3/2 (CW) } (A1, A2): 9, (A2, A3): 9, (A3, A4): 9, (A4, A1): 9, (A1, OO, A2): 9, (A2, OO, A3): 9, (A3, OO, A4): 9, (A4, OO, A1): 9, # A --- L ---> A => { +3/2 (CCW), -1/2 (CW) } (A1, A4): 10, (A2, A1): 10, (A3, A2): 10, (A4, A3): 10, (A1, OO, A4): 10, (A2, OO, A1): 10, (A3, OO, A2): 10, (A4, OO, A3): 10, # Q --- 1 ---> A => { +3/4 (CCW), -5/4 (CW) } (Q1, A3): 11, (Q2, A4): 11, (Q3, A1): 11, (Q4, A2): 11, (Q1, OO, A3): 11, (Q2, OO, A4): 11, (Q3, OO, A1): 11, (Q4, OO, A2): 11, # Q --- 2 ---> A => { +5/4 (CCW), -3/4 (CW) } (Q1, A4): 12, (Q2, A1): 12, (Q3, A2): 12, (Q4, A3): 12, (Q1, OO, A4): 12, (Q2, OO, A1): 12, (Q3, OO, A2): 12, (Q4, OO, A3): 12, # A --- 1 ---> Q => { +5/4 (CCW), -3/4 (CW) } (A1, Q3): 13, (A2, Q4): 13, (A3, Q1): 13, (A4, Q2): 13, (A1, OO, Q3): 13, (A2, OO, Q4): 13, (A3, OO, Q1): 13, (A4, OO, Q2): 13, # A --- 2 ---> Q => { +3/4 (CCW), -5/4 (CW) } (A1, Q2): 14, (A2, Q3): 14, (A3, Q4): 14, (A4, Q1): 14, (A1, OO, Q2): 14, (A2, OO, Q3): 14, (A3, OO, Q4): 14, (A4, OO, Q1): 14, # Q --> OO --> Q => { +1/2 (CCW), -3/2 (CW) } (Q1, OO, Q2): 15, (Q2, OO, Q3): 15, (Q3, OO, Q4): 15, (Q4, OO, Q1): 15, # Q --> OO --> Q => { +3/2 (CCW), -1/2 (CW) } (Q1, OO, Q4): 16, (Q2, OO, Q1): 16, (Q3, OO, Q2): 16, (Q4, OO, Q3): 16, # A --> OO --> A => { +2 (CCW), 0 (CW) } (A1, OO, A1): 17, (A2, OO, A2): 17, (A3, OO, A3): 17, (A4, OO, A4): 17, # Q --> OO --> Q => { +2 (CCW), 0 (CW) } (Q1, OO, Q1): 18, (Q2, OO, Q2): 18, (Q3, OO, Q3): 18, (Q4, OO, Q4): 18, } _values = { 0: [( 0, 1)], 1: [(+1, 4)], 2: [(-1, 4)], 3: [(+1, 4)], 4: [(-1, 4)], -1: [(+9, 4), (+1, 4)], -2: [(+7, 4), (-1, 4)], -3: [(+9, 4), (+1, 4)], -4: [(+7, 4), (-1, 4)], +5: [(+1, 2)], -5: [(-1, 2)], 7: [(+1, 1), (-1, 1)], 8: [(+1, 1), (-1, 1)], 9: [(+1, 2), (-3, 2)], 10: [(+3, 2), (-1, 2)], 11: [(+3, 4), (-5, 4)], 12: [(+5, 4), (-3, 4)], 13: [(+5, 4), (-3, 4)], 14: [(+3, 4), (-5, 4)], 15: [(+1, 2), (-3, 2)], 16: [(+3, 2), (-1, 2)], 17: [(+2, 1), ( 0, 1)], 18: [(+2, 1), ( 0, 1)], } def _classify_point(re, im): """Return the half-axis (or origin) on which (re, im) point is located. """ if not re and not im: return OO if not re: if im > 0: return A2 else: return A4 elif not im: if re > 0: return A1 else: return A3 def _intervals_to_quadrants(intervals, f1, f2, s, t, F): """Generate a sequence of extended quadrants from a list of critical points. """ if not intervals: return [] Q = [] if not f1: (a, b), _, _ = intervals[0] if a == b == s: if len(intervals) == 1: if dup_eval(f2, t, F) > 0: return [OO, A2] else: return [OO, A4] else: (a, _), _, _ = intervals[1] if dup_eval(f2, (s + a)/2, F) > 0: Q.extend([OO, A2]) f2_sgn = +1 else: Q.extend([OO, A4]) f2_sgn = -1 intervals = intervals[1:] else: if dup_eval(f2, s, F) > 0: Q.append(A2) f2_sgn = +1 else: Q.append(A4) f2_sgn = -1 for (a, _), indices, _ in intervals: Q.append(OO) if indices[1] % 2 == 1: f2_sgn = -f2_sgn if a != t: if f2_sgn > 0: Q.append(A2) else: Q.append(A4) return Q if not f2: (a, b), _, _ = intervals[0] if a == b == s: if len(intervals) == 1: if dup_eval(f1, t, F) > 0: return [OO, A1] else: return [OO, A3] else: (a, _), _, _ = intervals[1] if dup_eval(f1, (s + a)/2, F) > 0: Q.extend([OO, A1]) f1_sgn = +1 else: Q.extend([OO, A3]) f1_sgn = -1 intervals = intervals[1:] else: if dup_eval(f1, s, F) > 0: Q.append(A1) f1_sgn = +1 else: Q.append(A3) f1_sgn = -1 for (a, _), indices, _ in intervals: Q.append(OO) if indices[0] % 2 == 1: f1_sgn = -f1_sgn if a != t: if f1_sgn > 0: Q.append(A1) else: Q.append(A3) return Q re = dup_eval(f1, s, F) im = dup_eval(f2, s, F) if not re or not im: Q.append(_classify_point(re, im)) if len(intervals) == 1: re = dup_eval(f1, t, F) im = dup_eval(f2, t, F) else: (a, _), _, _ = intervals[1] re = dup_eval(f1, (s + a)/2, F) im = dup_eval(f2, (s + a)/2, F) intervals = intervals[1:] if re > 0: f1_sgn = +1 else: f1_sgn = -1 if im > 0: f2_sgn = +1 else: f2_sgn = -1 sgn = { (+1, +1): Q1, (-1, +1): Q2, (-1, -1): Q3, (+1, -1): Q4, } Q.append(sgn[(f1_sgn, f2_sgn)]) for (a, b), indices, _ in intervals: if a == b: re = dup_eval(f1, a, F) im = dup_eval(f2, a, F) cls = _classify_point(re, im) if cls is not None: Q.append(cls) if 0 in indices: if indices[0] % 2 == 1: f1_sgn = -f1_sgn if 1 in indices: if indices[1] % 2 == 1: f2_sgn = -f2_sgn if not (a == b and b == t): Q.append(sgn[(f1_sgn, f2_sgn)]) return Q def _traverse_quadrants(Q_L1, Q_L2, Q_L3, Q_L4, exclude=None): """Transform sequences of quadrants to a sequence of rules. """ if exclude is True: edges = [1, 1, 0, 0] corners = { (0, 1): 1, (1, 2): 1, (2, 3): 0, (3, 0): 1, } else: edges = [0, 0, 0, 0] corners = { (0, 1): 0, (1, 2): 0, (2, 3): 0, (3, 0): 0, } if exclude is not None and exclude is not True: exclude = set(exclude) for i, edge in enumerate(['S', 'E', 'N', 'W']): if edge in exclude: edges[i] = 1 for i, corner in enumerate(['SW', 'SE', 'NE', 'NW']): if corner in exclude: corners[((i - 1) % 4, i)] = 1 QQ, rules = [Q_L1, Q_L2, Q_L3, Q_L4], [] for i, Q in enumerate(QQ): if not Q: continue if Q[-1] == OO: Q = Q[:-1] if Q[0] == OO: j, Q = (i - 1) % 4, Q[1:] qq = (QQ[j][-2], OO, Q[0]) if qq in _rules_ambiguous: rules.append((_rules_ambiguous[qq], corners[(j, i)])) else: raise NotImplementedError("3 element rule (corner): " + str(qq)) q1, k = Q[0], 1 while k < len(Q): q2, k = Q[k], k + 1 if q2 != OO: qq = (q1, q2) if qq in _rules_simple: rules.append((_rules_simple[qq], 0)) elif qq in _rules_ambiguous: rules.append((_rules_ambiguous[qq], edges[i])) else: raise NotImplementedError("2 element rule (inside): " + str(qq)) else: qq, k = (q1, q2, Q[k]), k + 1 if qq in _rules_ambiguous: rules.append((_rules_ambiguous[qq], edges[i])) else: raise NotImplementedError("3 element rule (edge): " + str(qq)) q1 = qq[-1] return rules def _reverse_intervals(intervals): """Reverse intervals for traversal from right to left and from top to bottom. """ return [ ((b, a), indices, f) for (a, b), indices, f in reversed(intervals) ] def _winding_number(T, field): """Compute the winding number of the input polynomial, i.e. the number of roots. """ return int(sum([ field(_values[t][i]) for t, i in T ]) / field(2)) def dup_count_complex_roots(f, K, inf=None, sup=None, exclude=None): """Count all roots in [u + vI, s + tI] rectangle using Collins-Krandick algorithm. """ if not K.is_ZZ and not K.is_QQ: raise DomainError("complex root counting is not supported over %s" % K) if K.is_ZZ: R, F = K, K.get_field() else: R, F = K.get_ring(), K f = dup_convert(f, K, F) if inf is None or sup is None: _, lc = dup_degree(f), abs(dup_LC(f, F)) B = 2max([ F.quo(abs(c), lc) for c in f ]) if inf is None: (u, v) = (-B, -B) else: (u, v) = inf if sup is None: (s, t) = (+B, +B) else: (s, t) = sup f1, f2 = dup_real_imag(f, F) f1L1F = dmp_eval_in(f1, v, 1, 1, F) f2L1F = dmp_eval_in(f2, v, 1, 1, F) _, f1L1R = dup_clear_denoms(f1L1F, F, R, convert=True) _, f2L1R = dup_clear_denoms(f2L1F, F, R, convert=True) f1L2F = dmp_eval_in(f1, s, 0, 1, F) f2L2F = dmp_eval_in(f2, s, 0, 1, F) _, f1L2R = dup_clear_denoms(f1L2F, F, R, convert=True) _, f2L2R = dup_clear_denoms(f2L2F, F, R, convert=True) f1L3F = dmp_eval_in(f1, t, 1, 1, F) f2L3F = dmp_eval_in(f2, t, 1, 1, F) _, f1L3R = dup_clear_denoms(f1L3F, F, R, convert=True) _, f2L3R = dup_clear_denoms(f2L3F, F, R, convert=True) f1L4F = dmp_eval_in(f1, u, 0, 1, F) f2L4F = dmp_eval_in(f2, u, 0, 1, F) _, f1L4R = dup_clear_denoms(f1L4F, F, R, convert=True) _, f2L4R = dup_clear_denoms(f2L4F, F, R, convert=True) S_L1 = [f1L1R, f2L1R] S_L2 = [f1L2R, f2L2R] S_L3 = [f1L3R, f2L3R] S_L4 = [f1L4R, f2L4R] I_L1 = dup_isolate_real_roots_list(S_L1, R, inf=u, sup=s, fast=True, basis=True, strict=True) I_L2 = dup_isolate_real_roots_list(S_L2, R, inf=v, sup=t, fast=True, basis=True, strict=True) I_L3 = dup_isolate_real_roots_list(S_L3, R, inf=u, sup=s, fast=True, basis=True, strict=True) I_L4 = dup_isolate_real_roots_list(S_L4, R, inf=v, sup=t, fast=True, basis=True, strict=True) I_L3 = _reverse_intervals(I_L3) I_L4 = _reverse_intervals(I_L4) Q_L1 = _intervals_to_quadrants(I_L1, f1L1F, f2L1F, u, s, F) Q_L2 = _intervals_to_quadrants(I_L2, f1L2F, f2L2F, v, t, F) Q_L3 = _intervals_to_quadrants(I_L3, f1L3F, f2L3F, s, u, F) Q_L4 = _intervals_to_quadrants(I_L4, f1L4F, f2L4F, t, v, F) T = _traverse_quadrants(Q_L1, Q_L2, Q_L3, Q_L4, exclude=exclude) return _winding_number(T, F) def _vertical_bisection(N, a, b, I, Q, F1, F2, f1, f2, F): """Vertical bisection step in Collins-Krandick root isolation algorithm. """ (u, v), (s, t) = a, b I_L1, I_L2, I_L3, I_L4 = I Q_L1, Q_L2, Q_L3, Q_L4 = Q f1L1F, f1L2F, f1L3F, f1L4F = F1 f2L1F, f2L2F, f2L3F, f2L4F = F2 x = (u + s) / 2 f1V = dmp_eval_in(f1, x, 0, 1, F) f2V = dmp_eval_in(f2, x, 0, 1, F) I_V = dup_isolate_real_roots_list([f1V, f2V], F, inf=v, sup=t, fast=True, strict=True, basis=True) I_L1_L, I_L1_R = [], [] I_L2_L, I_L2_R = I_V, I_L2 I_L3_L, I_L3_R = [], [] I_L4_L, I_L4_R = I_L4, _reverse_intervals(I_V) for I in I_L1: (a, b), indices, h = I if a == b: if a == x: I_L1_L.append(I) I_L1_R.append(I) elif a < x: I_L1_L.append(I) else: I_L1_R.append(I) else: if b <= x: I_L1_L.append(I) elif a >= x: I_L1_R.append(I) else: a, b = dup_refine_real_root(h, a, b, F.get_ring(), disjoint=x, fast=True) if b <= x: I_L1_L.append(((a, b), indices, h)) if a >= x: I_L1_R.append(((a, b), indices, h)) for I in I_L3: (b, a), indices, h = I if a == b: if a == x: I_L3_L.append(I) I_L3_R.append(I) elif a < x: I_L3_L.append(I) else: I_L3_R.append(I) else: if b <= x: I_L3_L.append(I) elif a >= x: I_L3_R.append(I) else: a, b = dup_refine_real_root(h, a, b, F.get_ring(), disjoint=x, fast=True) if b <= x: I_L3_L.append(((b, a), indices, h)) if a >= x: I_L3_R.append(((b, a), indices, h)) Q_L1_L = _intervals_to_quadrants(I_L1_L, f1L1F, f2L1F, u, x, F) Q_L2_L = _intervals_to_quadrants(I_L2_L, f1V, f2V, v, t, F) Q_L3_L = _intervals_to_quadrants(I_L3_L, f1L3F, f2L3F, x, u, F) Q_L4_L = Q_L4 Q_L1_R = _intervals_to_quadrants(I_L1_R, f1L1F, f2L1F, x, s, F) Q_L2_R = Q_L2 Q_L3_R = _intervals_to_quadrants(I_L3_R, f1L3F, f2L3F, s, x, F) Q_L4_R = _intervals_to_quadrants(I_L4_R, f1V, f2V, t, v, F) T_L = _traverse_quadrants(Q_L1_L, Q_L2_L, Q_L3_L, Q_L4_L, exclude=True) T_R = _traverse_quadrants(Q_L1_R, Q_L2_R, Q_L3_R, Q_L4_R, exclude=True) N_L = _winding_number(T_L, F) N_R = _winding_number(T_R, F) I_L = (I_L1_L, I_L2_L, I_L3_L, I_L4_L) Q_L = (Q_L1_L, Q_L2_L, Q_L3_L, Q_L4_L) I_R = (I_L1_R, I_L2_R, I_L3_R, I_L4_R) Q_R = (Q_L1_R, Q_L2_R, Q_L3_R, Q_L4_R) F1_L = (f1L1F, f1V, f1L3F, f1L4F) F2_L = (f2L1F, f2V, f2L3F, f2L4F) F1_R = (f1L1F, f1L2F, f1L3F, f1V) F2_R = (f2L1F, f2L2F, f2L3F, f2V) a, b = (u, v), (x, t) c, d = (x, v), (s, t) D_L = (N_L, a, b, I_L, Q_L, F1_L, F2_L) D_R = (N_R, c, d, I_R, Q_R, F1_R, F2_R) return D_L, D_R def _horizontal_bisection(N, a, b, I, Q, F1, F2, f1, f2, F): """Horizontal bisection step in Collins-Krandick root isolation algorithm. """ (u, v), (s, t) = a, b I_L1, I_L2, I_L3, I_L4 = I Q_L1, Q_L2, Q_L3, Q_L4 = Q f1L1F, f1L2F, f1L3F, f1L4F = F1 f2L1F, f2L2F, f2L3F, f2L4F = F2 y = (v + t) / 2 f1H = dmp_eval_in(f1, y, 1, 1, F) f2H = dmp_eval_in(f2, y, 1, 1, F) I_H = dup_isolate_real_roots_list([f1H, f2H], F, inf=u, sup=s, fast=True, strict=True, basis=True) I_L1_B, I_L1_U = I_L1, I_H I_L2_B, I_L2_U = [], [] I_L3_B, I_L3_U = _reverse_intervals(I_H), I_L3 I_L4_B, I_L4_U = [], [] for I in I_L2: (a, b), indices, h = I if a == b: if a == y: I_L2_B.append(I) I_L2_U.append(I) elif a < y: I_L2_B.append(I) else: I_L2_U.append(I) else: if b <= y: I_L2_B.append(I) elif a >= y: I_L2_U.append(I) else: a, b = dup_refine_real_root(h, a, b, F.get_ring(), disjoint=y, fast=True) if b <= y: I_L2_B.append(((a, b), indices, h)) if a >= y: I_L2_U.append(((a, b), indices, h)) for I in I_L4: (b, a), indices, h = I if a == b: if a == y: I_L4_B.append(I) I_L4_U.append(I) elif a < y: I_L4_B.append(I) else: I_L4_U.append(I) else: if b <= y: I_L4_B.append(I) elif a >= y: I_L4_U.append(I) else: a, b = dup_refine_real_root(h, a, b, F.get_ring(), disjoint=y, fast=True) if b <= y: I_L4_B.append(((b, a), indices, h)) if a >= y: I_L4_U.append(((b, a), indices, h)) Q_L1_B = Q_L1 Q_L2_B = _intervals_to_quadrants(I_L2_B, f1L2F, f2L2F, v, y, F) Q_L3_B = _intervals_to_quadrants(I_L3_B, f1H, f2H, s, u, F) Q_L4_B = _intervals_to_quadrants(I_L4_B, f1L4F, f2L4F, y, v, F) Q_L1_U = _intervals_to_quadrants(I_L1_U, f1H, f2H, u, s, F) Q_L2_U = _intervals_to_quadrants(I_L2_U, f1L2F, f2L2F, y, t, F) Q_L3_U = Q_L3 Q_L4_U = _intervals_to_quadrants(I_L4_U, f1L4F, f2L4F, t, y, F) T_B = _traverse_quadrants(Q_L1_B, Q_L2_B, Q_L3_B, Q_L4_B, exclude=True) T_U = _traverse_quadrants(Q_L1_U, Q_L2_U, Q_L3_U, Q_L4_U, exclude=True) N_B = _winding_number(T_B, F) N_U = _winding_number(T_U, F) I_B = (I_L1_B, I_L2_B, I_L3_B, I_L4_B) Q_B = (Q_L1_B, Q_L2_B, Q_L3_B, Q_L4_B) I_U = (I_L1_U, I_L2_U, I_L3_U, I_L4_U) Q_U = (Q_L1_U, Q_L2_U, Q_L3_U, Q_L4_U) F1_B = (f1L1F, f1L2F, f1H, f1L4F) F2_B = (f2L1F, f2L2F, f2H, f2L4F) F1_U = (f1H, f1L2F, f1L3F, f1L4F) F2_U = (f2H, f2L2F, f2L3F, f2L4F) a, b = (u, v), (s, y) c, d = (u, y), (s, t) D_B = (N_B, a, b, I_B, Q_B, F1_B, F2_B) D_U = (N_U, c, d, I_U, Q_U, F1_U, F2_U) return D_B, D_U def _depth_first_select(rectangles): """Find a rectangle of minimum area for bisection. """ min_area, j = None, None for i, (_, (u, v), (s, t), _, _, _, _) in enumerate(rectangles): area = (s - u)(t - v) if min_area is None or area < min_area: min_area, j = area, i return rectangles.pop(j) def _rectangle_small_p(a, b, eps): """Return ``True`` if the given rectangle is small enough. """ (u, v), (s, t) = a, b if eps is not None: return s - u < eps and t - v < eps else: return True def dup_isolate_complex_roots_sqf(f, K, eps=None, inf=None, sup=None, blackbox=False): """Isolate complex roots of a square-free polynomial using Collins-Krandick algorithm. """ if not K.is_ZZ and not K.is_QQ: raise DomainError("isolation of complex roots is not supported over %s" % K) if dup_degree(f) <= 0: return [] if K.is_ZZ: F = K.get_field() else: F = K f = dup_convert(f, K, F) lc = abs(dup_LC(f, F)) B = 2max([ F.quo(abs(c), lc) for c in f ]) (u, v), (s, t) = (-B, F.zero), (B, B) if inf is not None: u = inf if sup is not None: s = sup if v < 0 or t <= v or s <= u: raise ValueError("not a valid complex isolation rectangle") f1, f2 = dup_real_imag(f, F) f1L1 = dmp_eval_in(f1, v, 1, 1, F) f2L1 = dmp_eval_in(f2, v, 1, 1, F) f1L2 = dmp_eval_in(f1, s, 0, 1, F) f2L2 = dmp_eval_in(f2, s, 0, 1, F) f1L3 = dmp_eval_in(f1, t, 1, 1, F) f2L3 = dmp_eval_in(f2, t, 1, 1, F) f1L4 = dmp_eval_in(f1, u, 0, 1, F) f2L4 = dmp_eval_in(f2, u, 0, 1, F) S_L1 = [f1L1, f2L1] S_L2 = [f1L2, f2L2] S_L3 = [f1L3, f2L3] S_L4 = [f1L4, f2L4] I_L1 = dup_isolate_real_roots_list(S_L1, F, inf=u, sup=s, fast=True, strict=True, basis=True) I_L2 = dup_isolate_real_roots_list(S_L2, F, inf=v, sup=t, fast=True, strict=True, basis=True) I_L3 = dup_isolate_real_roots_list(S_L3, F, inf=u, sup=s, fast=True, strict=True, basis=True) I_L4 = dup_isolate_real_roots_list(S_L4, F, inf=v, sup=t, fast=True, strict=True, basis=True) I_L3 = _reverse_intervals(I_L3) I_L4 = _reverse_intervals(I_L4) Q_L1 = _intervals_to_quadrants(I_L1, f1L1, f2L1, u, s, F) Q_L2 = _intervals_to_quadrants(I_L2, f1L2, f2L2, v, t, F) Q_L3 = _intervals_to_quadrants(I_L3, f1L3, f2L3, s, u, F) Q_L4 = _intervals_to_quadrants(I_L4, f1L4, f2L4, t, v, F) T = _traverse_quadrants(Q_L1, Q_L2, Q_L3, Q_L4) N = _winding_number(T, F) if not N: return [] I = (I_L1, I_L2, I_L3, I_L4) Q = (Q_L1, Q_L2, Q_L3, Q_L4) F1 = (f1L1, f1L2, f1L3, f1L4) F2 = (f2L1, f2L2, f2L3, f2L4) rectangles, roots = [(N, (u, v), (s, t), I, Q, F1, F2)], [] while rectangles: N, (u, v), (s, t), I, Q, F1, F2 = _depth_first_select(rectangles) if s - u > t - v: D_L, D_R = _vertical_bisection(N, (u, v), (s, t), I, Q, F1, F2, f1, f2, F) N_L, a, b, I_L, Q_L, F1_L, F2_L = D_L N_R, c, d, I_R, Q_R, F1_R, F2_R = D_R if N_L >= 1: if N_L == 1 and _rectangle_small_p(a, b, eps): roots.append(ComplexInterval(a, b, I_L, Q_L, F1_L, F2_L, f1, f2, F)) else: rectangles.append(D_L) if N_R >= 1: if N_R == 1 and _rectangle_small_p(c, d, eps): roots.append(ComplexInterval(c, d, I_R, Q_R, F1_R, F2_R, f1, f2, F)) else: rectangles.append(D_R) else: D_B, D_U = _horizontal_bisection(N, (u, v), (s, t), I, Q, F1, F2, f1, f2, F) N_B, a, b, I_B, Q_B, F1_B, F2_B = D_B N_U, c, d, I_U, Q_U, F1_U, F2_U = D_U if N_B >= 1: if N_B == 1 and _rectangle_small_p(a, b, eps): roots.append(ComplexInterval( a, b, I_B, Q_B, F1_B, F2_B, f1, f2, F)) else: rectangles.append(D_B) if N_U >= 1: if N_U == 1 and _rectangle_small_p(c, d, eps): roots.append(ComplexInterval( c, d, I_U, Q_U, F1_U, F2_U, f1, f2, F)) else: rectangles.append(D_U) _roots, roots = sorted(roots, key=lambda r: (r.ax, r.ay)), [] for root in _roots: roots.extend([root.conjugate(), root]) if blackbox: return roots else: return [ r.as_tuple() for r in roots ] def dup_isolate_all_roots_sqf(f, K, eps=None, inf=None, sup=None, fast=False, blackbox=False): """Isolate real and complex roots of a square-free polynomial ``f``. """ return ( dup_isolate_real_roots_sqf( f, K, eps=eps, inf=inf, sup=sup, fast=fast, blackbox=blackbox), dup_isolate_complex_roots_sqf(f, K, eps=eps, inf=inf, sup=sup, blackbox=blackbox)) def dup_isolate_all_roots(f, K, eps=None, inf=None, sup=None, fast=False): """Isolate real and complex roots of a non-square-free polynomial ``f``. """ if not K.is_ZZ and not K.is_QQ: raise DomainError("isolation of real and complex roots is not supported over %s" % K) _, factors = dup_sqf_list(f, K) if len(factors) == 1: ((f, k),) = factors real_part, complex_part = dup_isolate_all_roots_sqf( f, K, eps=eps, inf=inf, sup=sup, fast=fast) real_part = [ ((a, b), k) for (a, b) in real_part ] complex_part = [ ((a, b), k) for (a, b) in complex_part ] return real_part, complex_part else: raise NotImplementedError( "only trivial square-free polynomials are supported") class RealInterval(object): """A fully qualified representation of a real isolation interval. """ def __init__(self, data, f, dom): """Initialize new real interval with complete information. """ if len(data) == 2: s, t = data self.neg = False if s < 0: if t <= 0: f, s, t, self.neg = dup_mirror(f, dom), -t, -s, True else: raise ValueError("can't refine a real root in (%s, %s)" % (s, t)) a, b, c, d = _mobius_from_interval((s, t), dom.get_field()) f = dup_transform(f, dup_strip([a, b]), dup_strip([c, d]), dom) self.mobius = a, b, c, d else: self.mobius = data[:-1] self.neg = data[-1] self.f, self.dom = f, dom @property def func(self): return RealInterval @property def args(self): i = self return (i.mobius + (i.neg,), i.f, i.dom) def __eq__(self, other): if type(other) != type(self): return False return self.args == other.args @property def a(self): """Return the position of the left end. """ field = self.dom.get_field() a, b, c, d = self.mobius if not self.neg: if ad < bc: return field(a, c) return field(b, d) else: if ad > bc: return -field(a, c) return -field(b, d) @property def b(self): """Return the position of the right end. """ was = self.neg self.neg = not was rv = -self.a self.neg = was return rv @property def dx(self): """Return width of the real isolating interval. """ return self.b - self.a @property def center(self): """Return the center of the real isolating interval. """ return (self.a + self.b)/2 def as_tuple(self): """Return tuple representation of real isolating interval. """ return (self.a, self.b) def __repr__(self): return "(%s, %s)" % (self.a, self.b) def is_disjoint(self, other): """Return ``True`` if two isolation intervals are disjoint. """ if isinstance(other, RealInterval): return (self.b <= other.a or other.b <= self.a) assert isinstance(other, ComplexInterval) return (self.b <= other.ax or other.bx <= self.a or other.ayother.by > 0) def _inner_refine(self): """Internal one step real root refinement procedure. """ if self.mobius is None: return self f, mobius = dup_inner_refine_real_root( self.f, self.mobius, self.dom, steps=1, mobius=True) return RealInterval(mobius + (self.neg,), f, self.dom) def refine_disjoint(self, other): """Refine an isolating interval until it is disjoint with another one. """ expr = self while not expr.is_disjoint(other): expr, other = expr._inner_refine(), other._inner_refine() return expr, other def refine_size(self, dx): """Refine an isolating interval until it is of sufficiently small size. """ expr = self while not (expr.dx < dx): expr = expr._inner_refine() return expr def refine_step(self, steps=1): """Perform several steps of real root refinement algorithm. """ expr = self for _ in range(steps): expr = expr._inner_refine() return expr def refine(self): """Perform one step of real root refinement algorithm. """ return self._inner_refine() class ComplexInterval(object): """A fully qualified representation of a complex isolation interval. The printed form is shown as (ax, bx) x (ay, by) where (ax, ay) and (bx, by) are the coordinates of the southwest and northeast corners of the interval's rectangle, respectively. Examples ======== >>> from sympy import CRootOf, Rational, S >>> from sympy.abc import x >>> CRootOf.clear_cache() # for doctest reproducibility >>> root = CRootOf(x*10 - 2x + 3, 9) >>> i = root._get_interval(); i (3/64, 3/32) x (9/8, 75/64) The real part of the root lies within the range [0, 3/4] while the imaginary part lies within the range [9/8, 3/2]: >>> root.n(3) 0.0766 + 1.14I The width of the ranges in the x and y directions on the complex plane are: >>> i.dx, i.dy (3/64, 3/64) The center of the range is >>> i.center (9/128, 147/128) The northeast coordinate of the rectangle bounding the root in the complex plane is given by attribute b and the x and y components are accessed by bx and by: >>> i.b, i.bx, i.by ((3/32, 75/64), 3/32, 75/64) The southwest coordinate is similarly given by i.a >>> i.a, i.ax, i.ay ((3/64, 9/8), 3/64, 9/8) Although the interval prints to show only the real and imaginary range of the root, all the information of the underlying root is contained as properties of the interval. For example, an interval with a nonpositive imaginary range is considered to be the conjugate. Since the y values of y are in the range [0, 1/4] it is not the conjugate: >>> i.conj False The conjugate's interval is >>> ic = i.conjugate(); ic (3/64, 3/32) x (-75/64, -9/8) NOTE: the values printed still represent the x and y range in which the root -- conjugate, in this case -- is located, but the underlying a and b values of a root and its conjugate are the same: >>> assert i.a == ic.a and i.b == ic.b What changes are the reported coordinates of the bounding rectangle: >>> (i.ax, i.ay), (i.bx, i.by) ((3/64, 9/8), (3/32, 75/64)) >>> (ic.ax, ic.ay), (ic.bx, ic.by) ((3/64, -75/64), (3/32, -9/8)) The interval can be refined once: >>> i # for reference, this is the current interval (3/64, 3/32) x (9/8, 75/64) >>> i.refine() (3/64, 3/32) x (9/8, 147/128) Several refinement steps can be taken: >>> i.refine_step(2) # 2 steps (9/128, 3/32) x (9/8, 147/128) It is also possible to refine to a given tolerance: >>> tol = min(i.dx, i.dy)/2 >>> i.refine_size(tol) (9/128, 21/256) x (9/8, 291/256) A disjoint interval is one whose bounding rectangle does not overlap with another. An interval, necessarily, is not disjoint with itself, but any interval is disjoint with a conjugate since the conjugate rectangle will always be in the lower half of the complex plane and the non-conjugate in the upper half: >>> i.is_disjoint(i), i.is_disjoint(i.conjugate()) (False, True) The following interval j is not disjoint from i: >>> close = CRootOf(x10 - 2x + 300/S(101), 9) >>> j = close._get_interval(); j (75/1616, 75/808) x (225/202, 1875/1616) >>> i.is_disjoint(j) False The two can be made disjoint, however: >>> newi, newj = i.refine_disjoint(j) >>> newi (39/512, 159/2048) x (2325/2048, 4653/4096) >>> newj (3975/51712, 2025/25856) x (29325/25856, 117375/103424) Even though the real ranges overlap, the imaginary do not, so the roots have been resolved as distinct. Intervals are disjoint when either the real or imaginary component of the intervals is distinct. In the case above, the real components have not been resolved (so we don't know, yet, which root has the smaller real part) but the imaginary part of ``close`` is larger than ``root``: >>> close.n(3) 0.0771 + 1.13I >>> root.n(3) 0.0766 + 1.14I """ def __init__(self, a, b, I, Q, F1, F2, f1, f2, dom, conj=False): """Initialize new complex interval with complete information. """ # a and b are the SW and NE corner of the bounding interval, # (ax, ay) and (bx, by), respectively, for the NON-CONJUGATE # root (the one with the positive imaginary part); when working # with the conjugate, the a and b value are still non-negative # but the ay, by are reversed and have oppositite sign self.a, self.b = a, b self.I, self.Q = I, Q self.f1, self.F1 = f1, F1 self.f2, self.F2 = f2, F2 self.dom = dom self.conj = conj @property def func(self): return ComplexInterval @property def args(self): i = self return (i.a, i.b, i.I, i.Q, i.F1, i.F2, i.f1, i.f2, i.dom, i.conj) def __eq__(self, other): if type(other) != type(self): return False return self.args == other.args @property def ax(self): """Return ``x`` coordinate of south-western corner. """ return self.a[0] @property def ay(self): """Return ``y`` coordinate of south-western corner. """ if not self.conj: return self.a[1] else: return -self.b[1] @property def bx(self): """Return ``x`` coordinate of north-eastern corner. """ return self.b[0] @property def by(self): """Return ``y`` coordinate of north-eastern corner. """ if not self.conj: return self.b[1] else: return -self.a[1] @property def dx(self): """Return width of the complex isolating interval. """ return self.b[0] - self.a[0] @property def dy(self): """Return height of the complex isolating interval. """ return self.b[1] - self.a[1] @property def center(self): """Return the center of the complex isolating interval. """ return ((self.ax + self.bx)/2, (self.ay + self.by)/2) def as_tuple(self): """Return tuple representation of the complex isolating interval's SW and NE corners, respectively. """ return ((self.ax, self.ay), (self.bx, self.by)) def __repr__(self): return "(%s, %s) x (%s, %s)" % (self.ax, self.bx, self.ay, self.by) def conjugate(self): """This complex interval really is located in lower half-plane. """ return ComplexInterval(self.a, self.b, self.I, self.Q, self.F1, self.F2, self.f1, self.f2, self.dom, conj=True) def is_disjoint(self, other): """Return ``True`` if two isolation intervals are disjoint. """ if isinstance(other, RealInterval): return other.is_disjoint(self) if self.conj != other.conj: # above and below real axis return True re_distinct = (self.bx <= other.ax or other.bx <= self.ax) if re_distinct: return True im_distinct = (self.by <= other.ay or other.by <= self.ay) return im_distinct def _inner_refine(self): """Internal one step complex root refinement procedure. """ (u, v), (s, t) = self.a, self.b I, Q = self.I, self.Q f1, F1 = self.f1, self.F1 f2, F2 = self.f2, self.F2 dom = self.dom if s - u > t - v: D_L, D_R = _vertical_bisection(1, (u, v), (s, t), I, Q, F1, F2, f1, f2, dom) if D_L[0] == 1: _, a, b, I, Q, F1, F2 = D_L else: _, a, b, I, Q, F1, F2 = D_R else: D_B, D_U = _horizontal_bisection(1, (u, v), (s, t), I, Q, F1, F2, f1, f2, dom) if D_B[0] == 1: _, a, b, I, Q, F1, F2 = D_B else: _, a, b, I, Q, F1, F2 = D_U return ComplexInterval(a, b, I, Q, F1, F2, f1, f2, dom, self.conj) def refine_disjoint(self, other): """Refine an isolating interval until it is disjoint with another one. """ expr = self while not expr.is_disjoint(other): expr, other = expr._inner_refine(), other._inner_refine() return expr, other def refine_size(self, dx, dy=None): """Refine an isolating interval until it is of sufficiently small size. """ if dy is None: dy = dx expr = self while not (expr.dx < dx and expr.dy < dy): expr = expr._inner_refine() return expr def refine_step(self, steps=1): """Perform several steps of complex root refinement algorithm. """ expr = self for _ in range(steps): expr = expr._inner_refine() return expr def refine(self): """Perform one step of complex root refinement algorithm. """ return self._inner_refine()
4f19bf1c3bf7ff4cccbe41f25c35c811e8eaf4931a09f588d648bf65abf428df	"""Efficient functions for generating orthogonal polynomials. """ from __future__ import print_function, division from sympy import Dummy from sympy.core.compatibility import range from sympy.polys.constructor import construct_domain from sympy.polys.densearith import ( dup_mul, dup_mul_ground, dup_lshift, dup_sub, dup_add ) from sympy.polys.domains import ZZ, QQ from sympy.polys.polyclasses import DMP from sympy.polys.polytools import Poly, PurePoly from sympy.utilities import public def dup_jacobi(n, a, b, K): """Low-level implementation of Jacobi polynomials. """ seq = [[K.one], [(a + b + K(2))/K(2), (a - b)/K(2)]] for i in range(2, n + 1): den = K(i)(a + b + i)(a + b + K(2)i - K(2)) f0 = (a + b + K(2)i - K.one) * (aa - bb) / (K(2)den) f1 = (a + b + K(2)i - K.one) * (a + b + K(2)i - K(2)) (a + b + K(2)i) / (K(2)den) f2 = (a + i - K.one)(b + i - K.one)(a + b + K(2)i) / den p0 = dup_mul_ground(seq[-1], f0, K) p1 = dup_mul_ground(dup_lshift(seq[-1], 1, K), f1, K) p2 = dup_mul_ground(seq[-2], f2, K) seq.append(dup_sub(dup_add(p0, p1, K), p2, K)) return seq[n] @public def jacobi_poly(n, a, b, x=None, polys=False): """Generates Jacobi polynomial of degree `n` in `x`. Parameters ========== n : int `n` decides the degree of polynomial a Lower limit of minimal domain for the list of coefficients. b Upper limit of minimal domain for the list of coefficients. x : optional polys : bool, optional ``polys=True`` returns an expression, otherwise (default) returns an expression. """ if n < 0: raise ValueError("can't generate Jacobi polynomial of degree %s" % n) K, v = construct_domain([a, b], field=True) poly = DMP(dup_jacobi(int(n), v[0], v[1], K), K) if x is not None: poly = Poly.new(poly, x) else: poly = PurePoly.new(poly, Dummy('x')) return poly if polys else poly.as_expr() def dup_gegenbauer(n, a, K): """Low-level implementation of Gegenbauer polynomials. """ seq = [[K.one], [K(2)a, K.zero]] for i in range(2, n + 1): f1 = K(2) * (i + a - K.one) / i f2 = (i + K(2)a - K(2)) / i p1 = dup_mul_ground(dup_lshift(seq[-1], 1, K), f1, K) p2 = dup_mul_ground(seq[-2], f2, K) seq.append(dup_sub(p1, p2, K)) return seq[n] def gegenbauer_poly(n, a, x=None, polys=False): """Generates Gegenbauer polynomial of degree `n` in `x`. Parameters ========== n : int `n` decides the degree of polynomial x : optional a Decides minimal domain for the list of coefficients. polys : bool, optional ``polys=True`` returns an expression, otherwise (default) returns an expression. """ if n < 0: raise ValueError( "can't generate Gegenbauer polynomial of degree %s" % n) K, a = construct_domain(a, field=True) poly = DMP(dup_gegenbauer(int(n), a, K), K) if x is not None: poly = Poly.new(poly, x) else: poly = PurePoly.new(poly, Dummy('x')) return poly if polys else poly.as_expr() def dup_chebyshevt(n, K): """Low-level implementation of Chebyshev polynomials of the 1st kind. """ seq = [[K.one], [K.one, K.zero]] for i in range(2, n + 1): a = dup_mul_ground(dup_lshift(seq[-1], 1, K), K(2), K) seq.append(dup_sub(a, seq[-2], K)) return seq[n] @public def chebyshevt_poly(n, x=None, polys=False): """Generates Chebyshev polynomial of the first kind of degree `n` in `x`. Parameters ========== n : int `n` decides the degree of polynomial x : optional polys : bool, optional ``polys=True`` returns an expression, otherwise (default) returns an expression. """ if n < 0: raise ValueError( "can't generate 1st kind Chebyshev polynomial of degree %s" % n) poly = DMP(dup_chebyshevt(int(n), ZZ), ZZ) if x is not None: poly = Poly.new(poly, x) else: poly = PurePoly.new(poly, Dummy('x')) return poly if polys else poly.as_expr() def dup_chebyshevu(n, K): """Low-level implementation of Chebyshev polynomials of the 2nd kind. """ seq = [[K.one], [K(2), K.zero]] for i in range(2, n + 1): a = dup_mul_ground(dup_lshift(seq[-1], 1, K), K(2), K) seq.append(dup_sub(a, seq[-2], K)) return seq[n] @public def chebyshevu_poly(n, x=None, polys=False): """Generates Chebyshev polynomial of the second kind of degree `n` in `x`. Parameters ========== n : int `n` decides the degree of polynomial x : optional polys : bool, optional ``polys=True`` returns an expression, otherwise (default) returns an expression. """ if n < 0: raise ValueError( "can't generate 2nd kind Chebyshev polynomial of degree %s" % n) poly = DMP(dup_chebyshevu(int(n), ZZ), ZZ) if x is not None: poly = Poly.new(poly, x) else: poly = PurePoly.new(poly, Dummy('x')) return poly if polys else poly.as_expr() def dup_hermite(n, K): """Low-level implementation of Hermite polynomials. """ seq = [[K.one], [K(2), K.zero]] for i in range(2, n + 1): a = dup_lshift(seq[-1], 1, K) b = dup_mul_ground(seq[-2], K(i - 1), K) c = dup_mul_ground(dup_sub(a, b, K), K(2), K) seq.append(c) return seq[n] @public def hermite_poly(n, x=None, polys=False): """Generates Hermite polynomial of degree `n` in `x`. Parameters ========== n : int `n` decides the degree of polynomial x : optional polys : bool, optional ``polys=True`` returns an expression, otherwise (default) returns an expression. """ if n < 0: raise ValueError("can't generate Hermite polynomial of degree %s" % n) poly = DMP(dup_hermite(int(n), ZZ), ZZ) if x is not None: poly = Poly.new(poly, x) else: poly = PurePoly.new(poly, Dummy('x')) return poly if polys else poly.as_expr() def dup_legendre(n, K): """Low-level implementation of Legendre polynomials. """ seq = [[K.one], [K.one, K.zero]] for i in range(2, n + 1): a = dup_mul_ground(dup_lshift(seq[-1], 1, K), K(2i - 1, i), K) b = dup_mul_ground(seq[-2], K(i - 1, i), K) seq.append(dup_sub(a, b, K)) return seq[n] @public def legendre_poly(n, x=None, polys=False): """Generates Legendre polynomial of degree `n` in `x`. Parameters ========== n : int `n` decides the degree of polynomial x : optional polys : bool, optional ``polys=True`` returns an expression, otherwise (default) returns an expression. """ if n < 0: raise ValueError("can't generate Legendre polynomial of degree %s" % n) poly = DMP(dup_legendre(int(n), QQ), QQ) if x is not None: poly = Poly.new(poly, x) else: poly = PurePoly.new(poly, Dummy('x')) return poly if polys else poly.as_expr() def dup_laguerre(n, alpha, K): """Low-level implementation of Laguerre polynomials. """ seq = [[K.zero], [K.one]] for i in range(1, n + 1): a = dup_mul(seq[-1], [-K.one/i, alpha/i + K(2i - 1)/i], K) b = dup_mul_ground(seq[-2], alpha/i + K(i - 1)/i, K) seq.append(dup_sub(a, b, K)) return seq[-1] @public def laguerre_poly(n, x=None, alpha=None, polys=False): """Generates Laguerre polynomial of degree `n` in `x`. Parameters ========== n : int `n` decides the degree of polynomial x : optional alpha Decides minimal domain for the list of coefficients. polys : bool, optional ``polys=True`` returns an expression, otherwise (default) returns an expression. """ if n < 0: raise ValueError("can't generate Laguerre polynomial of degree %s" % n) if alpha is not None: K, alpha = construct_domain( alpha, field=True) # XXX: ground_field=True else: K, alpha = QQ, QQ(0) poly = DMP(dup_laguerre(int(n), alpha, K), K) if x is not None: poly = Poly.new(poly, x) else: poly = PurePoly.new(poly, Dummy('x')) return poly if polys else poly.as_expr() def dup_spherical_bessel_fn(n, K): """ Low-level implementation of fn(n, x) """ seq = [[K.one], [K.one, K.zero]] for i in range(2, n + 1): a = dup_mul_ground(dup_lshift(seq[-1], 1, K), K(2i - 1), K) seq.append(dup_sub(a, seq[-2], K)) return dup_lshift(seq[n], 1, K) def dup_spherical_bessel_fn_minus(n, K): """ Low-level implementation of fn(-n, x) """ seq = [[K.one, K.zero], [K.zero]] for i in range(2, n + 1): a = dup_mul_ground(dup_lshift(seq[-1], 1, K), K(3 - 2i), K) seq.append(dup_sub(a, seq[-2], K)) return seq[n] def spherical_bessel_fn(n, x=None, polys=False): """ Coefficients for the spherical Bessel functions. Those are only needed in the jn() function. The coefficients are calculated from: fn(0, z) = 1/z fn(1, z) = 1/z2 fn(n-1, z) + fn(n+1, z) == (2n+1)/z * fn(n, z) Parameters ========== n : int `n` decides the degree of polynomial x : optional polys : bool, optional ``polys=True`` returns an expression, otherwise (default) returns an expression. Examples ======== >>> from sympy.polys.orthopolys import spherical_bessel_fn as fn >>> from sympy import Symbol >>> z = Symbol("z") >>> fn(1, z) z(-2) >>> fn(2, z) -1/z + 3/z3 >>> fn(3, z) -6/z2 + 15/z4 >>> fn(4, z) 1/z - 45/z3 + 105/z5 """ if n < 0: dup = dup_spherical_bessel_fn_minus(-int(n), ZZ) else: dup = dup_spherical_bessel_fn(int(n), ZZ) poly = DMP(dup, ZZ) if x is not None: poly = Poly.new(poly, 1/x) else: poly = PurePoly.new(poly, 1/Dummy('x')) return poly if polys else poly.as_expr()
21c45aeb6339a7e50862531c8ec3a51c306cd66f441f224ceaf7f664f763b731	""" This module contains functions for two multivariate resultants. These are: - Dixon's resultant. - Macaulay's resultant. Multivariate resultants are used to identify whether a multivariate system has common roots. That is when the resultant is equal to zero. """ from sympy import IndexedBase, Matrix, Mul, Poly from sympy import rem, prod, total_degree from sympy.core.compatibility import range from sympy.polys.monomials import monomial_deg, itermonomials from sympy.polys.orderings import monomial_key from sympy.polys.polytools import poly_from_expr from sympy.functions.combinatorial.factorials import binomial from itertools import combinations_with_replacement class DixonResultant(): """ A class for retrieving the Dixon's resultant of a multivariate system. Examples ======== >>> from sympy.core import symbols >>> from sympy.polys.multivariate_resultants import DixonResultant >>> x, y = symbols('x, y') >>> p = x + y >>> q = x 2 + y 3 >>> h = x ** 2 + y >>> dixon = DixonResultant(variables=[x, y], polynomials=[p, q, h]) >>> poly = dixon.get_dixon_polynomial() >>> matrix = dixon.get_dixon_matrix(polynomial=poly) >>> matrix Matrix([ [ 0, 0, -1, 0, -1], [ 0, -1, 0, -1, 0], [-1, 0, 1, 0, 0], [ 0, -1, 0, 0, 1], [-1, 0, 0, 1, 0]]) >>> matrix.det() 0 See Also ======== Notebook in examples: sympy/example/notebooks. References ========== .. [1] [Kapur1994]_ .. [2] [Palancz08]_ """ def __init__(self, polynomials, variables): """ A class that takes two lists, a list of polynomials and list of variables. Returns the Dixon matrix of the multivariate system. Parameters ---------- polynomials : list of polynomials A list of m n-degree polynomials variables: list A list of all n variables """ self.polynomials = polynomials self.variables = variables self.n = len(self.variables) self.m = len(self.polynomials) a = IndexedBase("alpha") # A list of n alpha variables (the replacing variables) self.dummy_variables = [a[i] for i in range(self.n)] # A list of the d_max of each variable. self.max_degrees = [total_degree(poly, self.variables) for poly in self.polynomials] def get_dixon_polynomial(self): r""" Returns ======= dixon_polynomial: polynomial Dixon's polynomial is calculated as: delta = Delta(A) / ((x_1 - a_1) ... (x_n - a_n)) where, A = \|p_1(x_1,... x_n), ..., p_n(x_1,... x_n)\| \|p_1(a_1,... x_n), ..., p_n(a_1,... x_n)\| \|... , ..., ...\| \|p_1(a_1,... a_n), ..., p_n(a_1,... a_n)\| """ if self.m != (self.n + 1): raise ValueError('Method invalid for given combination.') # First row rows = [self.polynomials] temp = list(self.variables) for idx in range(self.n): temp[idx] = self.dummy_variables[idx] substitution = {var: t for var, t in zip(self.variables, temp)} rows.append([f.subs(substitution) for f in self.polynomials]) A = Matrix(rows) terms = zip(self.variables, self.dummy_variables) product_of_differences = Mul([a - b for a, b in terms]) dixon_polynomial = (A.det() / product_of_differences).factor() return poly_from_expr(dixon_polynomial, self.dummy_variables)[0] def get_upper_degree(self): list_of_products = [self.variables[i] ** ((i + 1) * self.max_degrees[i] - 1) for i in range(self.n)] product = prod(list_of_products) product = Poly(product).monoms() return monomial_deg(product) def get_dixon_matrix(self, polynomial): r""" Construct the Dixon matrix from the coefficients of polynomial \alpha. Each coefficient is viewed as a polynomial of x_1, ..., x_n. """ # A list of coefficients (in x_i, ..., x_n terms) of the power # products a_1, ..., a_n in Dixon's polynomial. coefficients = polynomial.coeffs() monomials = list(itermonomials(self.variables, self.get_upper_degree())) monomials = sorted(monomials, reverse=True, key=monomial_key('lex', self.variables)) dixon_matrix = Matrix([[Poly(c, self.variables).coeff_monomial(m) for m in monomials] for c in coefficients]) keep = [column for column in range(dixon_matrix.shape[-1]) if any([element != 0 for element in dixon_matrix[:, column]])] return dixon_matrix[:, keep] class MacaulayResultant(): """ A class for calculating the Macaulay resultant. Note that the coefficients of the polynomials must be given as symbols. Examples ======== >>> from sympy.core import symbols >>> from sympy.polys.multivariate_resultants import MacaulayResultant >>> x, y, z = symbols('x, y, z') >>> a_0, a_1, a_2 = symbols('a_0, a_1, a_2') >>> b_0, b_1, b_2 = symbols('b_0, b_1, b_2') >>> c_0, c_1, c_2,c_3, c_4 = symbols('c_0, c_1, c_2, c_3, c_4') >>> f = a_0 * y - a_1 * x + a_2 * z >>> g = b_1 * x ** 2 + b_0 * y ** 2 - b_2 * z ** 2 >>> h = c_0 * y - c_1 * x ** 3 + c_2 * x ** 2 * z - c_3 * x * z ** 2 + c_4 * z ** 3 >>> mac = MacaulayResultant(polynomials=[f, g, h], variables=[x, y, z]) >>> mac.get_monomials_set() >>> matrix = mac.get_matrix() >>> submatrix = mac.get_submatrix(matrix) >>> submatrix Matrix([ [-a_1, a_0, a_2, 0], [ 0, -a_1, 0, 0], [ 0, 0, -a_1, 0], [ 0, 0, 0, -a_1]]) See Also ======== Notebook in examples: sympy/example/notebooks. References ========== .. [1] [Bruce97]_ .. [2] [Stiller96]_ """ def __init__(self, polynomials, variables): """ Parameters ========== variables: list A list of all n variables polynomials : list of sympy polynomials A list of m n-degree polynomials """ self.polynomials = polynomials self.variables = variables self.n = len(variables) # A list of the d_max of each variable. self.degrees = [total_degree(poly, self.variables) for poly in self.polynomials] self.degree_m = self._get_degree_m() self.monomials_size = self.get_size() def _get_degree_m(self): r""" Returns ======= degree_m: int The degree_m is calculated as 1 + \sum_1 ^ n (d_i - 1), where d_i is the degree of the i polynomial """ return 1 + sum(d - 1 for d in self.degrees) def get_size(self): r""" Returns ======= size: int The size of set T. Set T is the set of all possible monomials of the n variables for degree equal to the degree_m """ return binomial(self.degree_m + self.n - 1, self.n - 1) def get_monomials_of_certain_degree(self, degree): """ Returns ======= monomials: list A list of monomials of a certain degree. """ monomials = [Mul(monomial) for monomial in combinations_with_replacement(self.variables, degree)] return sorted(monomials, reverse=True, key=monomial_key('lex', self.variables)) def get_monomials_set(self): r""" Returns ======= self.monomial_set: set The set T. Set of all possible monomials of degree degree_m """ monomial_set = self.get_monomials_of_certain_degree(self.degree_m) self.monomial_set = monomial_set def get_row_coefficients(self): """ Returns ======= row_coefficients: list The row coefficients of Macaulay's matrix """ row_coefficients = [] divisible = [] for i in range(self.n): if i == 0: degree = self.degree_m - self.degrees[i] monomial = self.get_monomials_of_certain_degree(degree) row_coefficients.append(monomial) else: divisible.append(self.variables[i - 1] ** self.degrees[i - 1]) degree = self.degree_m - self.degrees[i] poss_rows = self.get_monomials_of_certain_degree(degree) for div in divisible: for p in poss_rows: if rem(p, div) == 0: poss_rows = [item for item in poss_rows if item != p] row_coefficients.append(poss_rows) return row_coefficients def get_matrix(self): """ Returns ======= macaulay_matrix: Matrix The Macaulay's matrix """ rows = [] row_coefficients = self.get_row_coefficients() for i in range(self.n): for multiplier in row_coefficients[i]: coefficients = [] poly = Poly(self.polynomials[i] * multiplier, self.variables) for mono in self.monomial_set: coefficients.append(poly.coeff_monomial(mono)) rows.append(coefficients) macaulay_matrix = Matrix(rows) return macaulay_matrix def get_reduced_nonreduced(self): r""" Returns ======= reduced: list A list of the reduced monomials non_reduced: list A list of the monomials that are not reduced Definition ========== A polynomial is said to be reduced in x_i, if its degree (the maximum degree of its monomials) in x_i is less than d_i. A polynomial that is reduced in all variables but one is said simply to be reduced. """ divisible = [] for m in self.monomial_set: temp = [] for i, v in enumerate(self.variables): temp.append(bool(total_degree(m, v) >= self.degrees[i])) divisible.append(temp) reduced = [i for i, r in enumerate(divisible) if sum(r) < self.n - 1] non_reduced = [i for i, r in enumerate(divisible) if sum(r) >= self.n -1] return reduced, non_reduced def get_submatrix(self, matrix): r""" Returns ======= macaulay_submatrix: Matrix The Macaulay's matrix. Columns that are non reduced are kept. The row which contain one if the a_{i}s is dropped. a_{i}s are the coefficients of x_i ^ {d_i}. """ reduced, non_reduced = self.get_reduced_nonreduced() reduction_set = [v * self.degrees[i] for i, v in enumerate(self.variables)] ais = list([self.polynomials[i].coeff(reduction_set[i]) for i in range(self.n)]) reduced_matrix = matrix[:, reduced] keep = [] for row in range(reduced_matrix.rows): check = [ai in reduced_matrix[row, :] for ai in ais] if True not in check: keep.append(row) return matrix[keep, non_reduced]
5f2679b7bcb3e68a6b5866ae0b64d7d1e9dfef5b39c556cca9dd7fcaeddeea5a	"""Useful utilities for higher level polynomial classes. """ from __future__ import print_function, division from sympy.core import (S, Add, Mul, Pow, Expr, expand_mul, expand_multinomial) from sympy.core.compatibility import range from sympy.core.exprtools import decompose_power, decompose_power_rat from sympy.polys.polyerrors import PolynomialError, GeneratorsError from sympy.polys.polyoptions import build_options import re _gens_order = { 'a': 301, 'b': 302, 'c': 303, 'd': 304, 'e': 305, 'f': 306, 'g': 307, 'h': 308, 'i': 309, 'j': 310, 'k': 311, 'l': 312, 'm': 313, 'n': 314, 'o': 315, 'p': 216, 'q': 217, 'r': 218, 's': 219, 't': 220, 'u': 221, 'v': 222, 'w': 223, 'x': 124, 'y': 125, 'z': 126, } _max_order = 1000 _re_gen = re.compile(r"^(.+?)(\d)$") def _nsort(roots, separated=False): """Sort the numerical roots putting the real roots first, then sorting according to real and imaginary parts. If ``separated`` is True, then the real and imaginary roots will be returned in two lists, respectively. This routine tries to avoid issue 6137 by separating the roots into real and imaginary parts before evaluation. In addition, the sorting will raise an error if any computation cannot be done with precision. """ if not all(r.is_number for r in roots): raise NotImplementedError # see issue 6137: # get the real part of the evaluated real and imaginary parts of each root key = [[i.n(2).as_real_imag()[0] for i in r.as_real_imag()] for r in roots] # make sure the parts were computed with precision if any(i._prec == 1 for k in key for i in k): raise NotImplementedError("could not compute root with precision") # insert a key to indicate if the root has an imaginary part key = [(1 if i else 0, r, i) for r, i in key] key = sorted(zip(key, roots)) # return the real and imaginary roots separately if desired if separated: r = [] i = [] for (im, _, _), v in key: if im: i.append(v) else: r.append(v) return r, i _, roots = zip(key) return list(roots) def _sort_gens(gens, *args): """Sort generators in a reasonably intelligent way. """ opt = build_options(args) gens_order, wrt = {}, None if opt is not None: gens_order, wrt = {}, opt.wrt for i, gen in enumerate(opt.sort): gens_order[gen] = i + 1 def order_key(gen): gen = str(gen) if wrt is not None: try: return (-len(wrt) + wrt.index(gen), gen, 0) except ValueError: pass name, index = _re_gen.match(gen).groups() if index: index = int(index) else: index = 0 try: return ( gens_order[name], name, index) except KeyError: pass try: return (_gens_order[name], name, index) except KeyError: pass return (_max_order, name, index) try: gens = sorted(gens, key=order_key) except TypeError: # pragma: no cover pass return tuple(gens) def _unify_gens(f_gens, g_gens): """Unify generators in a reasonably intelligent way. """ f_gens = list(f_gens) g_gens = list(g_gens) if f_gens == g_gens: return tuple(f_gens) gens, common, k = [], [], 0 for gen in f_gens: if gen in g_gens: common.append(gen) for i, gen in enumerate(g_gens): if gen in common: g_gens[i], k = common[k], k + 1 for gen in common: i = f_gens.index(gen) gens.extend(f_gens[:i]) f_gens = f_gens[i + 1:] i = g_gens.index(gen) gens.extend(g_gens[:i]) g_gens = g_gens[i + 1:] gens.append(gen) gens.extend(f_gens) gens.extend(g_gens) return tuple(gens) def _analyze_gens(gens): """Support for passing generators as `gens` and `[gens]`. """ if len(gens) == 1 and hasattr(gens[0], '__iter__'): return tuple(gens[0]) else: return tuple(gens) def _sort_factors(factors, *args): """Sort low-level factors in increasing 'complexity' order. """ def order_if_multiple_key(factor): (f, n) = factor return (len(f), n, f) def order_no_multiple_key(f): return (len(f), f) if args.get('multiple', True): return sorted(factors, key=order_if_multiple_key) else: return sorted(factors, key=order_no_multiple_key) def _not_a_coeff(expr): """Do not treat NaN and infinities as valid polynomial coefficients. """ return expr in [S.NaN, S.Infinity, S.NegativeInfinity, S.ComplexInfinity] def _parallel_dict_from_expr_if_gens(exprs, opt): """Transform expressions into a multinomial form given generators. """ k, indices = len(opt.gens), {} for i, g in enumerate(opt.gens): indices[g] = i polys = [] for expr in exprs: poly = {} if expr.is_Equality: expr = expr.lhs - expr.rhs for term in Add.make_args(expr): coeff, monom = [], [0]k for factor in Mul.make_args(term): if not _not_a_coeff(factor) and factor.is_Number: coeff.append(factor) else: try: if opt.series is False: base, exp = decompose_power(factor) if exp < 0: exp, base = -exp, Pow(base, -S.One) else: base, exp = decompose_power_rat(factor) monom[indices[base]] = exp except KeyError: if not factor.free_symbols.intersection(opt.gens): coeff.append(factor) else: raise PolynomialError("%s contains an element of " "the set of generators." % factor) monom = tuple(monom) if monom in poly: poly[monom] += Mul(coeff) else: poly[monom] = Mul(coeff) polys.append(poly) return polys, opt.gens def _parallel_dict_from_expr_no_gens(exprs, opt): """Transform expressions into a multinomial form and figure out generators. """ if opt.domain is not None: def _is_coeff(factor): return factor in opt.domain elif opt.extension is True: def _is_coeff(factor): return factor.is_algebraic elif opt.greedy is not False: def _is_coeff(factor): return False else: def _is_coeff(factor): return factor.is_number gens, reprs = set([]), [] for expr in exprs: terms = [] if expr.is_Equality: expr = expr.lhs - expr.rhs for term in Add.make_args(expr): coeff, elements = [], {} for factor in Mul.make_args(term): if not _not_a_coeff(factor) and (factor.is_Number or _is_coeff(factor)): coeff.append(factor) else: if opt.series is False: base, exp = decompose_power(factor) if exp < 0: exp, base = -exp, Pow(base, -S.One) else: base, exp = decompose_power_rat(factor) elements[base] = elements.setdefault(base, 0) + exp gens.add(base) terms.append((coeff, elements)) reprs.append(terms) gens = _sort_gens(gens, opt=opt) k, indices = len(gens), {} for i, g in enumerate(gens): indices[g] = i polys = [] for terms in reprs: poly = {} for coeff, term in terms: monom = [0]k for base, exp in term.items(): monom[indices[base]] = exp monom = tuple(monom) if monom in poly: poly[monom] += Mul(coeff) else: poly[monom] = Mul(coeff) polys.append(poly) return polys, tuple(gens) def _dict_from_expr_if_gens(expr, opt): """Transform an expression into a multinomial form given generators. """ (poly,), gens = _parallel_dict_from_expr_if_gens((expr,), opt) return poly, gens def _dict_from_expr_no_gens(expr, opt): """Transform an expression into a multinomial form and figure out generators. """ (poly,), gens = _parallel_dict_from_expr_no_gens((expr,), opt) return poly, gens def parallel_dict_from_expr(exprs, args): """Transform expressions into a multinomial form. """ reps, opt = _parallel_dict_from_expr(exprs, build_options(args)) return reps, opt.gens def _parallel_dict_from_expr(exprs, opt): """Transform expressions into a multinomial form. """ if opt.expand is not False: exprs = [ expr.expand() for expr in exprs ] if any(expr.is_commutative is False for expr in exprs): raise PolynomialError('non-commutative expressions are not supported') if opt.gens: reps, gens = _parallel_dict_from_expr_if_gens(exprs, opt) else: reps, gens = _parallel_dict_from_expr_no_gens(exprs, opt) return reps, opt.clone({'gens': gens}) def dict_from_expr(expr, args): """Transform an expression into a multinomial form. """ rep, opt = _dict_from_expr(expr, build_options(args)) return rep, opt.gens def _dict_from_expr(expr, opt): """Transform an expression into a multinomial form. """ if expr.is_commutative is False: raise PolynomialError('non-commutative expressions are not supported') def _is_expandable_pow(expr): return (expr.is_Pow and expr.exp.is_positive and expr.exp.is_Integer and expr.base.is_Add) if opt.expand is not False: if not isinstance(expr, Expr): raise PolynomialError('expression must be of type Expr') expr = expr.expand() # TODO: Integrate this into expand() itself while any(_is_expandable_pow(i) or i.is_Mul and any(_is_expandable_pow(j) for j in i.args) for i in Add.make_args(expr)): expr = expand_multinomial(expr) while any(i.is_Mul and any(j.is_Add for j in i.args) for i in Add.make_args(expr)): expr = expand_mul(expr) if opt.gens: rep, gens = _dict_from_expr_if_gens(expr, opt) else: rep, gens = _dict_from_expr_no_gens(expr, opt) return rep, opt.clone({'gens': gens}) def expr_from_dict(rep, gens): """Convert a multinomial form into an expression. """ result = [] for monom, coeff in rep.items(): term = [coeff] for g, m in zip(gens, monom): if m: term.append(Pow(g, m)) result.append(Mul(term)) return Add(result) parallel_dict_from_basic = parallel_dict_from_expr dict_from_basic = dict_from_expr basic_from_dict = expr_from_dict def _dict_reorder(rep, gens, new_gens): """Reorder levels using dict representation. """ gens = list(gens) monoms = rep.keys() coeffs = rep.values() new_monoms = [ [] for _ in range(len(rep)) ] used_indices = set() for gen in new_gens: try: j = gens.index(gen) used_indices.add(j) for M, new_M in zip(monoms, new_monoms): new_M.append(M[j]) except ValueError: for new_M in new_monoms: new_M.append(0) for i, _ in enumerate(gens): if i not in used_indices: for monom in monoms: if monom[i]: raise GeneratorsError("unable to drop generators") return map(tuple, new_monoms), coeffs class PicklableWithSlots(object): """ Mixin class that allows to pickle objects with ``__slots__``. Examples ======== First define a class that mixes :class:`PicklableWithSlots` in:: >>> from sympy.polys.polyutils import PicklableWithSlots >>> class Some(PicklableWithSlots): ... __slots__ = ['foo', 'bar'] ... ... def __init__(self, foo, bar): ... self.foo = foo ... self.bar = bar To make :mod:`pickle` happy in doctest we have to use these hacks:: >>> from sympy.core.compatibility import builtins >>> builtins.Some = Some >>> from sympy.polys import polyutils >>> polyutils.Some = Some Next lets see if we can create an instance, pickle it and unpickle:: >>> some = Some('abc', 10) >>> some.foo, some.bar ('abc', 10) >>> from pickle import dumps, loads >>> some2 = loads(dumps(some)) >>> some2.foo, some2.bar ('abc', 10) """ __slots__ = [] def __getstate__(self, cls=None): if cls is None: # This is the case for the instance that gets pickled cls = self.__class__ d = {} # Get all data that should be stored from super classes for c in cls.__bases__: if hasattr(c, "__getstate__"): d.update(c.__getstate__(self, c)) # Get all information that should be stored from cls and return the dict for name in cls.__slots__: if hasattr(self, name): d[name] = getattr(self, name) return d def __setstate__(self, d): # All values that were pickled are now assigned to a fresh instance for name, value in d.items(): try: setattr(self, name, value) except AttributeError: # This is needed in cases like Rational :> Half pass
104c89f3399e9289a4c10d28b80c9e9674938cd18663b027f1bf93110aa9b7dd	"""Computational algebraic field theory. """ from __future__ import print_function, division from sympy import ( S, Rational, AlgebraicNumber, Add, Mul, sympify, Dummy, expand_mul, I, pi ) from sympy.core.compatibility import reduce, range from sympy.core.exprtools import Factors from sympy.core.function import _mexpand from sympy.functions.elementary.exponential import exp from sympy.functions.elementary.trigonometric import cos, sin from sympy.ntheory import sieve from sympy.ntheory.factor_ import divisors from sympy.polys.domains import ZZ, QQ from sympy.polys.orthopolys import dup_chebyshevt from sympy.polys.polyerrors import ( IsomorphismFailed, CoercionFailed, NotAlgebraic, GeneratorsError, ) from sympy.polys.polytools import ( Poly, PurePoly, invert, factor_list, groebner, resultant, degree, poly_from_expr, parallel_poly_from_expr, lcm ) from sympy.polys.polyutils import dict_from_expr, expr_from_dict from sympy.polys.ring_series import rs_compose_add from sympy.polys.rings import ring from sympy.polys.rootoftools import CRootOf from sympy.polys.specialpolys import cyclotomic_poly from sympy.printing.lambdarepr import LambdaPrinter from sympy.simplify.radsimp import _split_gcd from sympy.simplify.simplify import _is_sum_surds from sympy.utilities import ( numbered_symbols, variations, lambdify, public, sift ) from mpmath import pslq, mp def _choose_factor(factors, x, v, dom=QQ, prec=200, bound=5): """ Return a factor having root ``v`` It is assumed that one of the factors has root ``v``. """ if isinstance(factors[0], tuple): factors = [f[0] for f in factors] if len(factors) == 1: return factors[0] points = {x:v} symbols = dom.symbols if hasattr(dom, 'symbols') else [] t = QQ(1, 10) for n in range(boundlen(symbols)): prec1 = 10 n_temp = n for s in symbols: points[s] = n_temp % bound n_temp = n_temp // bound while True: candidates = [] eps = t(prec1 // 2) for f in factors: if abs(f.as_expr().evalf(prec1, points)) < eps: candidates.append(f) if candidates: factors = candidates if len(factors) == 1: return factors[0] if prec1 > prec: break prec1 = 2 raise NotImplementedError("multiple candidates for the minimal polynomial of %s" % v) def _separate_sq(p): """ helper function for ``_minimal_polynomial_sq`` It selects a rational ``g`` such that the polynomial ``p`` consists of a sum of terms whose surds squared have gcd equal to ``g`` and a sum of terms with surds squared prime with ``g``; then it takes the field norm to eliminate ``sqrt(g)`` See simplify.simplify.split_surds and polytools.sqf_norm. Examples ======== >>> from sympy import sqrt >>> from sympy.abc import x >>> from sympy.polys.numberfields import _separate_sq >>> p= -x + sqrt(2) + sqrt(3) + sqrt(7) >>> p = _separate_sq(p); p -x2 + 2sqrt(3)x + 2sqrt(7)x - 2sqrt(21) - 8 >>> p = _separate_sq(p); p -x*4 + 4sqrt(7)x3 - 32x*2 + 8sqrt(7)x + 20 >>> p = _separate_sq(p); p -x8 + 48x*6 - 536x*4 + 1728x*2 - 400 """ from sympy.utilities.iterables import sift def is_sqrt(expr): return expr.is_Pow and expr.exp is S.Half # p = c1sqrt(q1) + ... + cnsqrt(qn) -> a = [(c1, q1), .., (cn, qn)] a = [] for y in p.args: if not y.is_Mul: if is_sqrt(y): a.append((S.One, y2)) elif y.is_Atom: a.append((y, S.One)) elif y.is_Pow and y.exp.is_integer: a.append((y, S.One)) else: raise NotImplementedError continue T, F = sift(y.args, is_sqrt, binary=True) a.append((Mul(F), Mul(T)2)) a.sort(key=lambda z: z[1]) if a[-1][1] is S.One: # there are no surds return p surds = [z for y, z in a] for i in range(len(surds)): if surds[i] != 1: break g, b1, b2 = _split_gcd(surds[i:]) a1 = [] a2 = [] for y, z in a: if z in b1: a1.append(yzS.Half) else: a2.append(yz*S.Half) p1 = Add(a1) p2 = Add(a2) p = _mexpand(p12) - _mexpand(p22) return p def _minimal_polynomial_sq(p, n, x): """ Returns the minimal polynomial for the ``nth-root`` of a sum of surds or ``None`` if it fails. Parameters ========== p : sum of surds n : positive integer x : variable of the returned polynomial Examples ======== >>> from sympy.polys.numberfields import _minimal_polynomial_sq >>> from sympy import sqrt >>> from sympy.abc import x >>> q = 1 + sqrt(2) + sqrt(3) >>> _minimal_polynomial_sq(q, 3, x) x12 - 4x*9 - 4x*6 + 16x3 - 8 """ from sympy.simplify.simplify import _is_sum_surds p = sympify(p) n = sympify(n) if not n.is_Integer or not n > 0 or not _is_sum_surds(p): return None pn = pRational(1, n) # eliminate the square roots p -= x while 1: p1 = _separate_sq(p) if p1 is p: p = p1.subs({x:x*n}) break else: p = p1 # _separate_sq eliminates field extensions in a minimal way, so that # if n = 1 then `p = constant(minimal_polynomial(p))` # if n > 1 it contains the minimal polynomial as a factor. if n == 1: p1 = Poly(p) if p.coeff(xp1.degree(x)) < 0: p = -p p = p.primitive()[1] return p # by construction `p` has root `pn` # the minimal polynomial is the factor vanishing in x = pn factors = factor_list(p)[1] result = _choose_factor(factors, x, pn) return result def _minpoly_op_algebraic_element(op, ex1, ex2, x, dom, mp1=None, mp2=None): """ return the minimal polynomial for ``op(ex1, ex2)`` Parameters ========== op : operation ``Add`` or ``Mul`` ex1, ex2 : expressions for the algebraic elements x : indeterminate of the polynomials dom: ground domain mp1, mp2 : minimal polynomials for ``ex1`` and ``ex2`` or None Examples ======== >>> from sympy import sqrt, Add, Mul, QQ >>> from sympy.polys.numberfields import _minpoly_op_algebraic_element >>> from sympy.abc import x, y >>> p1 = sqrt(sqrt(2) + 1) >>> p2 = sqrt(sqrt(2) - 1) >>> _minpoly_op_algebraic_element(Mul, p1, p2, x, QQ) x - 1 >>> q1 = sqrt(y) >>> q2 = 1 / y >>> _minpoly_op_algebraic_element(Add, q1, q2, x, QQ.frac_field(y)) x2y2 - 2xy - y3 + 1 References ========== .. [1] https://en.wikipedia.org/wiki/Resultant .. [2] I.M. Isaacs, Proc. Amer. Math. Soc. 25 (1970), 638 "Degrees of sums in a separable field extension". """ y = Dummy(str(x)) if mp1 is None: mp1 = _minpoly_compose(ex1, x, dom) if mp2 is None: mp2 = _minpoly_compose(ex2, y, dom) else: mp2 = mp2.subs({x: y}) if op is Add: # mp1a = mp1.subs({x: x - y}) if dom == QQ: R, X = ring('X', QQ) p1 = R(dict_from_expr(mp1)[0]) p2 = R(dict_from_expr(mp2)[0]) else: (p1, p2), _ = parallel_poly_from_expr((mp1, x - y), x, y) r = p1.compose(p2) mp1a = r.as_expr() elif op is Mul: mp1a = _muly(mp1, x, y) else: raise NotImplementedError('option not available') if op is Mul or dom != QQ: r = resultant(mp1a, mp2, gens=[y, x]) else: r = rs_compose_add(p1, p2) r = expr_from_dict(r.as_expr_dict(), x) deg1 = degree(mp1, x) deg2 = degree(mp2, y) if op is Mul and deg1 == 1 or deg2 == 1: # if deg1 = 1, then mp1 = x - a; mp1a = x - y - a; # r = mp2(x - a), so that `r` is irreducible return r r = Poly(r, x, domain=dom) _, factors = r.factor_list() res = _choose_factor(factors, x, op(ex1, ex2), dom) return res.as_expr() def _invertx(p, x): """ Returns ``expand_mul(xdegree(p, x)p.subs(x, 1/x))`` """ p1 = poly_from_expr(p, x)[0] n = degree(p1) a = [c * x*(n - i) for (i,), c in p1.terms()] return Add(a) def _muly(p, x, y): """ Returns ``_mexpand(y*degp.subs({x:x / y}))`` """ p1 = poly_from_expr(p, x)[0] n = degree(p1) a = [c * x*i y*(n - i) for (i,), c in p1.terms()] return Add(a) def _minpoly_pow(ex, pw, x, dom, mp=None): """ Returns ``minpoly(expw, x)`` Parameters ========== ex : algebraic element pw : rational number x : indeterminate of the polynomial dom: ground domain mp : minimal polynomial of ``p`` Examples ======== >>> from sympy import sqrt, QQ, Rational >>> from sympy.polys.numberfields import _minpoly_pow, minpoly >>> from sympy.abc import x, y >>> p = sqrt(1 + sqrt(2)) >>> _minpoly_pow(p, 2, x, QQ) x2 - 2x - 1 >>> minpoly(p2, x) x2 - 2x - 1 >>> _minpoly_pow(y, Rational(1, 3), x, QQ.frac_field(y)) x3 - y >>> minpoly(yRational(1, 3), x) x3 - y """ pw = sympify(pw) if not mp: mp = _minpoly_compose(ex, x, dom) if not pw.is_rational: raise NotAlgebraic("%s doesn't seem to be an algebraic element" % ex) if pw < 0: if mp == x: raise ZeroDivisionError('%s is zero' % ex) mp = _invertx(mp, x) if pw == -1: return mp pw = -pw ex = 1/ex y = Dummy(str(x)) mp = mp.subs({x: y}) n, d = pw.as_numer_denom() res = Poly(resultant(mp, xd - yn, gens=[y]), x, domain=dom) _, factors = res.factor_list() res = _choose_factor(factors, x, expw, dom) return res.as_expr() def _minpoly_add(x, dom, a): """ returns ``minpoly(Add(a), dom, x)`` """ mp = _minpoly_op_algebraic_element(Add, a[0], a[1], x, dom) p = a[0] + a[1] for px in a[2:]: mp = _minpoly_op_algebraic_element(Add, p, px, x, dom, mp1=mp) p = p + px return mp def _minpoly_mul(x, dom, a): """ returns ``minpoly(Mul(a), dom, x)`` """ mp = _minpoly_op_algebraic_element(Mul, a[0], a[1], x, dom) p = a[0] * a[1] for px in a[2:]: mp = _minpoly_op_algebraic_element(Mul, p, px, x, dom, mp1=mp) p = p * px return mp def _minpoly_sin(ex, x): """ Returns the minimal polynomial of ``sin(ex)`` see http://mathworld.wolfram.com/TrigonometryAngles.html """ c, a = ex.args[0].as_coeff_Mul() if a is pi: if c.is_rational: n = c.q q = sympify(n) if q.is_prime: # for a = pip/q with q odd prime, using chebyshevt # write sin(qa) = mp(sin(a))sin(a); # the roots of mp(x) are sin(pip/q) for p = 1,..., q - 1 a = dup_chebyshevt(n, ZZ) return Add([x(n - i - 1)a[i] for i in range(n)]) if c.p == 1: if q == 9: return 64x6 - 96x*4 + 36x*2 - 3 if n % 2 == 1: # for a = pip/q with q odd, use # sin(qa) = 0 to see that the minimal polynomial must be # a factor of dup_chebyshevt(n, ZZ) a = dup_chebyshevt(n, ZZ) a = [x(n - i)a[i] for i in range(n + 1)] r = Add(a) _, factors = factor_list(r) res = _choose_factor(factors, x, ex) return res expr = ((1 - cos(2cpi))/2)S.Half res = _minpoly_compose(expr, x, QQ) return res raise NotAlgebraic("%s doesn't seem to be an algebraic element" % ex) def _minpoly_cos(ex, x): """ Returns the minimal polynomial of ``cos(ex)`` see http://mathworld.wolfram.com/TrigonometryAngles.html """ from sympy import sqrt c, a = ex.args[0].as_coeff_Mul() if a is pi: if c.is_rational: if c.p == 1: if c.q == 7: return 8x*3 - 4x*2 - 4x + 1 if c.q == 9: return 8x3 - 6x + 1 elif c.p == 2: q = sympify(c.q) if q.is_prime: s = _minpoly_sin(ex, x) return _mexpand(s.subs({x:sqrt((1 - x)/2)})) # for a = pip/q, cos(qa) =T_q(cos(a)) = (-1)p n = int(c.q) a = dup_chebyshevt(n, ZZ) a = [x(n - i)a[i] for i in range(n + 1)] r = Add(a) - (-1)*c.p _, factors = factor_list(r) res = _choose_factor(factors, x, ex) return res raise NotAlgebraic("%s doesn't seem to be an algebraic element" % ex) def _minpoly_exp(ex, x): """ Returns the minimal polynomial of ``exp(ex)`` """ c, a = ex.args[0].as_coeff_Mul() q = sympify(c.q) if a == Ipi: if c.is_rational: if c.p == 1 or c.p == -1: if q == 3: return x2 - x + 1 if q == 4: return x4 + 1 if q == 6: return x4 - x2 + 1 if q == 8: return x8 + 1 if q == 9: return x6 - x3 + 1 if q == 10: return x8 - x6 + x4 - x2 + 1 if q.is_prime: s = 0 for i in range(q): s += (-x)i return s # x*(2q) = product(factors) factors = [cyclotomic_poly(i, x) for i in divisors(2q)] mp = _choose_factor(factors, x, ex) return mp else: raise NotAlgebraic("%s doesn't seem to be an algebraic element" % ex) raise NotAlgebraic("%s doesn't seem to be an algebraic element" % ex) def _minpoly_rootof(ex, x): """ Returns the minimal polynomial of a ``CRootOf`` object. """ p = ex.expr p = p.subs({ex.poly.gens[0]:x}) _, factors = factor_list(p, x) result = _choose_factor(factors, x, ex) return result def _minpoly_compose(ex, x, dom): """ Computes the minimal polynomial of an algebraic element using operations on minimal polynomials Examples ======== >>> from sympy import minimal_polynomial, sqrt, Rational >>> from sympy.abc import x, y >>> minimal_polynomial(sqrt(2) + 3Rational(1, 3), x, compose=True) x*2 - 2x - 1 >>> minimal_polynomial(sqrt(y) + 1/y, x, compose=True) x*2y*2 - 2xy - y3 + 1 """ if ex.is_Rational: return ex.qx - ex.p if ex is I: _, factors = factor_list(x2 + 1, x, domain=dom) return x2 + 1 if len(factors) == 1 else x - I if hasattr(dom, 'symbols') and ex in dom.symbols: return x - ex if dom.is_QQ and _is_sum_surds(ex): # eliminate the square roots ex -= x while 1: ex1 = _separate_sq(ex) if ex1 is ex: return ex else: ex = ex1 if ex.is_Add: res = _minpoly_add(x, dom, ex.args) elif ex.is_Mul: f = Factors(ex).factors r = sift(f.items(), lambda itx: itx[0].is_Rational and itx[1].is_Rational) if r[True] and dom == QQ: ex1 = Mul([bxex for bx, ex in r[False] + r[None]]) r1 = dict(r[True]) dens = [y.q for y in r1.values()] lcmdens = reduce(lcm, dens, 1) neg1 = S.NegativeOne expn1 = r1.pop(neg1, S.Zero) nums = [base(y.plcmdens // y.q) for base, y in r1.items()] ex2 = Mul(nums) mp1 = minimal_polynomial(ex1, x) # use the fact that in SymPy canonicalization products of integers # raised to rational powers are organized in relatively prime # bases, and that in ``base*(n/d)`` a perfect power is # simplified with the root # Powers of -1 have to be treated separately to preserve sign. mp2 = ex2.qx*lcmdens - ex2.pneg1*(expn1lcmdens) ex2 = neg1*expn1 ex2*Rational(1, lcmdens) res = _minpoly_op_algebraic_element(Mul, ex1, ex2, x, dom, mp1=mp1, mp2=mp2) else: res = _minpoly_mul(x, dom, ex.args) elif ex.is_Pow: res = _minpoly_pow(ex.base, ex.exp, x, dom) elif ex.__class__ is sin: res = _minpoly_sin(ex, x) elif ex.__class__ is cos: res = _minpoly_cos(ex, x) elif ex.__class__ is exp: res = _minpoly_exp(ex, x) elif ex.__class__ is CRootOf: res = _minpoly_rootof(ex, x) else: raise NotAlgebraic("%s doesn't seem to be an algebraic element" % ex) return res @public def minimal_polynomial(ex, x=None, compose=True, polys=False, domain=None): """ Computes the minimal polynomial of an algebraic element. Parameters ========== ex : Expr Element or expression whose minimal polynomial is to be calculated. x : Symbol, optional Independent variable of the minimal polynomial compose : boolean, optional (default=True) Method to use for computing minimal polynomial. If ``compose=True`` (default) then ``_minpoly_compose`` is used, if ``compose=False`` then groebner bases are used. polys : boolean, optional (default=False) If ``True`` returns a ``Poly`` object else an ``Expr`` object. domain : Domain, optional Ground domain Notes ===== By default ``compose=True``, the minimal polynomial of the subexpressions of ``ex`` are computed, then the arithmetic operations on them are performed using the resultant and factorization. If ``compose=False``, a bottom-up algorithm is used with ``groebner``. The default algorithm stalls less frequently. If no ground domain is given, it will be generated automatically from the expression. Examples ======== >>> from sympy import minimal_polynomial, sqrt, solve, QQ >>> from sympy.abc import x, y >>> minimal_polynomial(sqrt(2), x) x2 - 2 >>> minimal_polynomial(sqrt(2), x, domain=QQ.algebraic_field(sqrt(2))) x - sqrt(2) >>> minimal_polynomial(sqrt(2) + sqrt(3), x) x4 - 10x2 + 1 >>> minimal_polynomial(solve(x3 + x + 3)[0], x) x3 + x + 3 >>> minimal_polynomial(sqrt(y), x) x2 - y """ from sympy.polys.polytools import degree from sympy.polys.domains import FractionField from sympy.core.basic import preorder_traversal ex = sympify(ex) if ex.is_number: # not sure if it's always needed but try it for numbers (issue 8354) ex = _mexpand(ex, recursive=True) for expr in preorder_traversal(ex): if expr.is_AlgebraicNumber: compose = False break if x is not None: x, cls = sympify(x), Poly else: x, cls = Dummy('x'), PurePoly if not domain: if ex.free_symbols: domain = FractionField(QQ, list(ex.free_symbols)) else: domain = QQ if hasattr(domain, 'symbols') and x in domain.symbols: raise GeneratorsError("the variable %s is an element of the ground " "domain %s" % (x, domain)) if compose: result = _minpoly_compose(ex, x, domain) result = result.primitive()[1] c = result.coeff(xdegree(result, x)) if c.is_negative: result = expand_mul(-result) return cls(result, x, field=True) if polys else result.collect(x) if not domain.is_QQ: raise NotImplementedError("groebner method only works for QQ") result = _minpoly_groebner(ex, x, cls) return cls(result, x, field=True) if polys else result.collect(x) def _minpoly_groebner(ex, x, cls): """ Computes the minimal polynomial of an algebraic number using Groebner bases Examples ======== >>> from sympy import minimal_polynomial, sqrt, Rational >>> from sympy.abc import x >>> minimal_polynomial(sqrt(2) + 3Rational(1, 3), x, compose=False) x*2 - 2x - 1 """ from sympy.polys.polytools import degree from sympy.core.function import expand_multinomial generator = numbered_symbols('a', cls=Dummy) mapping, symbols = {}, {} def update_mapping(ex, exp, base=None): a = next(generator) symbols[ex] = a if base is not None: mapping[ex] = a*exp + base else: mapping[ex] = exp.as_expr(a) return a def bottom_up_scan(ex): if ex.is_Atom: if ex is S.ImaginaryUnit: if ex not in mapping: return update_mapping(ex, 2, 1) else: return symbols[ex] elif ex.is_Rational: return ex elif ex.is_Add: return Add([ bottom_up_scan(g) for g in ex.args ]) elif ex.is_Mul: return Mul([ bottom_up_scan(g) for g in ex.args ]) elif ex.is_Pow: if ex.exp.is_Rational: if ex.exp < 0 and ex.base.is_Add: coeff, terms = ex.base.as_coeff_add() elt, _ = primitive_element(terms, polys=True) alg = ex.base - coeff # XXX: turn this into eval() inverse = invert(elt.gen + coeff, elt).as_expr() base = inverse.subs(elt.gen, alg).expand() if ex.exp == -1: return bottom_up_scan(base) else: ex = base(-ex.exp) if not ex.exp.is_Integer: base, exp = ( ex.baseex.exp.p).expand(), Rational(1, ex.exp.q) else: base, exp = ex.base, ex.exp base = bottom_up_scan(base) expr = baseexp if expr not in mapping: return update_mapping(expr, 1/exp, -base) else: return symbols[expr] elif ex.is_AlgebraicNumber: if ex.root not in mapping: return update_mapping(ex.root, ex.minpoly) else: return symbols[ex.root] raise NotAlgebraic("%s doesn't seem to be an algebraic number" % ex) def simpler_inverse(ex): """ Returns True if it is more likely that the minimal polynomial algorithm works better with the inverse """ if ex.is_Pow: if (1/ex.exp).is_integer and ex.exp < 0: if ex.base.is_Add: return True if ex.is_Mul: hit = True for p in ex.args: if p.is_Add: return False if p.is_Pow: if p.base.is_Add and p.exp > 0: return False if hit: return True return False inverted = False ex = expand_multinomial(ex) if ex.is_AlgebraicNumber: return ex.minpoly.as_expr(x) elif ex.is_Rational: result = ex.qx - ex.p else: inverted = simpler_inverse(ex) if inverted: ex = ex-1 res = None if ex.is_Pow and (1/ex.exp).is_Integer: n = 1/ex.exp res = _minimal_polynomial_sq(ex.base, n, x) elif _is_sum_surds(ex): res = _minimal_polynomial_sq(ex, S.One, x) if res is not None: result = res if res is None: bus = bottom_up_scan(ex) F = [x - bus] + list(mapping.values()) G = groebner(F, list(symbols.values()) + [x], order='lex') _, factors = factor_list(G[-1]) # by construction G[-1] has root `ex` result = _choose_factor(factors, x, ex) if inverted: result = _invertx(result, x) if result.coeff(xdegree(result, x)) < 0: result = expand_mul(-result) return result minpoly = minimal_polynomial __all__.append('minpoly') def _coeffs_generator(n): """Generate coefficients for `primitive_element()`. """ for coeffs in variations([1, -1, 2, -2, 3, -3], n, repetition=True): # Two linear combinations with coeffs of opposite signs are # opposites of each other. Hence it suffices to test only one. if coeffs[0] > 0: yield list(coeffs) @public def primitive_element(extension, x=None, *args): """Construct a common number field for all extensions. """ if not extension: raise ValueError("can't compute primitive element for empty extension") if x is not None: x, cls = sympify(x), Poly else: x, cls = Dummy('x'), PurePoly if not args.get('ex', False): gen, coeffs = extension[0], [1] # XXX when minimal_polynomial is extended to work # with AlgebraicNumbers this test can be removed if isinstance(gen, AlgebraicNumber): g = gen.minpoly.replace(x) else: g = minimal_polynomial(gen, x, polys=True) for ext in extension[1:]: _, factors = factor_list(g, extension=ext) g = _choose_factor(factors, x, gen) s, _, g = g.sqf_norm() gen += sext coeffs.append(s) if not args.get('polys', False): return g.as_expr(), coeffs else: return cls(g), coeffs generator = numbered_symbols('y', cls=Dummy) F, Y = [], [] for ext in extension: y = next(generator) if ext.is_Poly: if ext.is_univariate: f = ext.as_expr(y) else: raise ValueError("expected minimal polynomial, got %s" % ext) else: f = minpoly(ext, y) F.append(f) Y.append(y) coeffs_generator = args.get('coeffs', _coeffs_generator) for coeffs in coeffs_generator(len(Y)): f = x - sum([ cy for c, y in zip(coeffs, Y)]) G = groebner(F + [f], Y + [x], order='lex', field=True) H, g = G[:-1], cls(G[-1], x, domain='QQ') for i, (h, y) in enumerate(zip(H, Y)): try: H[i] = Poly(y - h, x, domain='QQ').all_coeffs() # XXX: composite=False except CoercionFailed: # pragma: no cover break # G is not a triangular set else: break else: # pragma: no cover raise RuntimeError("run out of coefficient configurations") _, g = g.clear_denoms() if not args.get('polys', False): return g.as_expr(), coeffs, H else: return g, coeffs, H def is_isomorphism_possible(a, b): """Returns `True` if there is a chance for isomorphism. """ n = a.minpoly.degree() m = b.minpoly.degree() if m % n != 0: return False if n == m: return True da = a.minpoly.discriminant() db = b.minpoly.discriminant() i, k, half = 1, m//n, db//2 while True: p = sieve[i] P = pk if P > half: break if ((da % p) % 2) and not (db % P): return False i += 1 return True def field_isomorphism_pslq(a, b): """Construct field isomorphism using PSLQ algorithm. """ if not a.root.is_real or not b.root.is_real: raise NotImplementedError("PSLQ doesn't support complex coefficients") f = a.minpoly g = b.minpoly.replace(f.gen) n, m, prev = 100, b.minpoly.degree(), None for i in range(1, 5): A = a.root.evalf(n) B = b.root.evalf(n) basis = [1, B] + [ Bi for i in range(2, m) ] + [A] dps, mp.dps = mp.dps, n coeffs = pslq(basis, maxcoeff=int(1e10), maxsteps=1000) mp.dps = dps if coeffs is None: break if coeffs != prev: prev = coeffs else: break coeffs = [S(c)/coeffs[-1] for c in coeffs[:-1]] while not coeffs[-1]: coeffs.pop() coeffs = list(reversed(coeffs)) h = Poly(coeffs, f.gen, domain='QQ') if f.compose(h).rem(g).is_zero: d, approx = len(coeffs) - 1, 0 for i, coeff in enumerate(coeffs): approx += coeffB*(d - i) if Aapprox < 0: return [ -c for c in coeffs ] else: return coeffs elif f.compose(-h).rem(g).is_zero: return [ -c for c in coeffs ] else: n = 2 return None def field_isomorphism_factor(a, b): """Construct field isomorphism via factorization. """ _, factors = factor_list(a.minpoly, extension=b) for f, _ in factors: if f.degree() == 1: coeffs = f.rep.TC().to_sympy_list() d, terms = len(coeffs) - 1, [] for i, coeff in enumerate(coeffs): terms.append(coeffb.root*(d - i)) root = Add(terms) if (a.root - root).evalf(chop=True) == 0: return coeffs if (a.root + root).evalf(chop=True) == 0: return [ -c for c in coeffs ] else: return None @public def field_isomorphism(a, b, args): """Construct an isomorphism between two number fields. """ a, b = sympify(a), sympify(b) if not a.is_AlgebraicNumber: a = AlgebraicNumber(a) if not b.is_AlgebraicNumber: b = AlgebraicNumber(b) if a == b: return a.coeffs() n = a.minpoly.degree() m = b.minpoly.degree() if n == 1: return [a.root] if m % n != 0: return None if args.get('fast', True): try: result = field_isomorphism_pslq(a, b) if result is not None: return result except NotImplementedError: pass return field_isomorphism_factor(a, b) @public def to_number_field(extension, theta=None, args): """Express `extension` in the field generated by `theta`. """ gen = args.get('gen') if hasattr(extension, '__iter__'): extension = list(extension) else: extension = [extension] if len(extension) == 1 and type(extension[0]) is tuple: return AlgebraicNumber(extension[0]) minpoly, coeffs = primitive_element(extension, gen, polys=True) root = sum([ coeffext for coeff, ext in zip(coeffs, extension) ]) if theta is None: return AlgebraicNumber((minpoly, root)) else: theta = sympify(theta) if not theta.is_AlgebraicNumber: theta = AlgebraicNumber(theta, gen=gen) coeffs = field_isomorphism(root, theta) if coeffs is not None: return AlgebraicNumber(theta, coeffs) else: raise IsomorphismFailed( "%s is not in a subfield of %s" % (root, theta.root)) class IntervalPrinter(LambdaPrinter): """Use ``lambda`` printer but print numbers as ``mpi`` intervals. """ def _print_Integer(self, expr): return "mpi('%s')" % super(IntervalPrinter, self)._print_Integer(expr) def _print_Rational(self, expr): return "mpi('%s')" % super(IntervalPrinter, self)._print_Rational(expr) def _print_Pow(self, expr): return super(IntervalPrinter, self)._print_Pow(expr, rational=True) @public def isolate(alg, eps=None, fast=False): """Give a rational isolating interval for an algebraic number. """ alg = sympify(alg) if alg.is_Rational: return (alg, alg) elif not alg.is_real: raise NotImplementedError( "complex algebraic numbers are not supported") func = lambdify((), alg, modules="mpmath", printer=IntervalPrinter()) poly = minpoly(alg, polys=True) intervals = poly.intervals(sqf=True) dps, done = mp.dps, False try: while not done: alg = func() for a, b in intervals: if a <= alg.a and alg.b <= b: done = True break else: mp.dps = 2 finally: mp.dps = dps if eps is not None: a, b = poly.refine_root(a, b, eps=eps, fast=fast) return (a, b)
5dfb18a1f688f3f7bf417a175597e1c2a8c4d90a138e38e1ab80ee38c84a7019	from __future__ import print_function, division from sympy.core import S from sympy.polys import Poly def dispersionset(p, q=None, gens, args): r"""Compute the dispersion set* of two polynomials. For two polynomials `f(x)` and `g(x)` with `\deg f > 0` and `\deg g > 0` the dispersion set `\operatorname{J}(f, g)` is defined as: .. math:: \operatorname{J}(f, g) & := \{a \in \mathbb{N}_0 \| \gcd(f(x), g(x+a)) \neq 1\} \\ & = \{a \in \mathbb{N}_0 \| \deg \gcd(f(x), g(x+a)) \geq 1\} For a single polynomial one defines `\operatorname{J}(f) := \operatorname{J}(f, f)`. Examples ======== >>> from sympy import poly >>> from sympy.polys.dispersion import dispersion, dispersionset >>> from sympy.abc import x Dispersion set and dispersion of a simple polynomial: >>> fp = poly((x - 3)(x + 3), x) >>> sorted(dispersionset(fp)) [0, 6] >>> dispersion(fp) 6 Note that the definition of the dispersion is not symmetric: >>> fp = poly(x4 - 3x2 + 1, x) >>> gp = fp.shift(-3) >>> sorted(dispersionset(fp, gp)) [2, 3, 4] >>> dispersion(fp, gp) 4 >>> sorted(dispersionset(gp, fp)) [] >>> dispersion(gp, fp) -oo Computing the dispersion also works over field extensions: >>> from sympy import sqrt >>> fp = poly(x2 + sqrt(5)x - 1, x, domain='QQ<sqrt(5)>') >>> gp = poly(x2 + (2 + sqrt(5))x + sqrt(5), x, domain='QQ<sqrt(5)>') >>> sorted(dispersionset(fp, gp)) [2] >>> sorted(dispersionset(gp, fp)) [1, 4] We can even perform the computations for polynomials having symbolic coefficients: >>> from sympy.abc import a >>> fp = poly(4x4 + (4a + 8)x3 + (a2 + 6a + 4)x2 + (a2 + 2a)x, x) >>> sorted(dispersionset(fp)) [0, 1] See Also ======== dispersion References ========== .. [1] [ManWright94]_ .. [2] [Koepf98]_ .. [3] [Abramov71]_ .. [4] [Man93]_ """ # Check for valid input same = False if q is not None else True if same: q = p p = Poly(p, gens, *args) q = Poly(q, gens, args) if not p.is_univariate or not q.is_univariate: raise ValueError("Polynomials need to be univariate") # The generator if not p.gen == q.gen: raise ValueError("Polynomials must have the same generator") gen = p.gen # We define the dispersion of constant polynomials to be zero if p.degree() < 1 or q.degree() < 1: return set([0]) # Factor p and q over the rationals fp = p.factor_list() fq = q.factor_list() if not same else fp # Iterate over all pairs of factors J = set([]) for s, unused in fp[1]: for t, unused in fq[1]: m = s.degree() n = t.degree() if n != m: continue an = s.LC() bn = t.LC() if not (an - bn).is_zero: continue # Note that the roles of `s` and `t` below are switched # w.r.t. the original paper. This is for consistency # with the description in the book of W. Koepf. anm1 = s.coeff_monomial(gen(m-1)) bnm1 = t.coeff_monomial(gen*(n-1)) alpha = (anm1 - bnm1) / S(nbn) if not alpha.is_integer: continue if alpha < 0 or alpha in J: continue if n > 1 and not (s - t.shift(alpha)).is_zero: continue J.add(alpha) return J def dispersion(p, q=None, gens, args): r"""Compute the dispersion* of polynomials. For two polynomials `f(x)` and `g(x)` with `\deg f > 0` and `\deg g > 0` the dispersion `\operatorname{dis}(f, g)` is defined as: .. math:: \operatorname{dis}(f, g) & := \max\{ J(f,g) \cup \{0\} \} \\ & = \max\{ \{a \in \mathbb{N} \| \gcd(f(x), g(x+a)) \neq 1\} \cup \{0\} \} and for a single polynomial `\operatorname{dis}(f) := \operatorname{dis}(f, f)`. Note that we make the definition `\max\{\} := -\infty`. Examples ======== >>> from sympy import poly >>> from sympy.polys.dispersion import dispersion, dispersionset >>> from sympy.abc import x Dispersion set and dispersion of a simple polynomial: >>> fp = poly((x - 3)(x + 3), x) >>> sorted(dispersionset(fp)) [0, 6] >>> dispersion(fp) 6 Note that the definition of the dispersion is not symmetric: >>> fp = poly(x4 - 3x2 + 1, x) >>> gp = fp.shift(-3) >>> sorted(dispersionset(fp, gp)) [2, 3, 4] >>> dispersion(fp, gp) 4 >>> sorted(dispersionset(gp, fp)) [] >>> dispersion(gp, fp) -oo The maximum of an empty set is defined to be `-\infty` as seen in this example. Computing the dispersion also works over field extensions: >>> from sympy import sqrt >>> fp = poly(x2 + sqrt(5)x - 1, x, domain='QQ<sqrt(5)>') >>> gp = poly(x2 + (2 + sqrt(5))x + sqrt(5), x, domain='QQ<sqrt(5)>') >>> sorted(dispersionset(fp, gp)) [2] >>> sorted(dispersionset(gp, fp)) [1, 4] We can even perform the computations for polynomials having symbolic coefficients: >>> from sympy.abc import a >>> fp = poly(4x4 + (4a + 8)x3 + (a2 + 6a + 4)x2 + (a2 + 2a)x, x) >>> sorted(dispersionset(fp)) [0, 1] See Also ======== dispersionset References ========== .. [1] [ManWright94]_ .. [2] [Koepf98]_ .. [3] [Abramov71]_ .. [4] [Man93]_ """ J = dispersionset(p, q, gens, **args) if not J: # Definition for maximum of empty set j = S.NegativeInfinity else: j = max(J) return j
8942501bff4bbf9fd07f7b2b3a43162be0c114262438228c91b1a920983987a0	"""Euclidean algorithms, GCDs, LCMs and polynomial remainder sequences. """ from __future__ import print_function, division from sympy.core.compatibility import range from sympy.ntheory import nextprime from sympy.polys.densearith import ( dup_sub_mul, dup_neg, dmp_neg, dmp_add, dmp_sub, dup_mul, dmp_mul, dmp_pow, dup_div, dmp_div, dup_rem, dup_quo, dmp_quo, dup_prem, dmp_prem, dup_mul_ground, dmp_mul_ground, dmp_mul_term, dup_quo_ground, dmp_quo_ground, dup_max_norm, dmp_max_norm) from sympy.polys.densebasic import ( dup_strip, dmp_raise, dmp_zero, dmp_one, dmp_ground, dmp_one_p, dmp_zero_p, dmp_zeros, dup_degree, dmp_degree, dmp_degree_in, dup_LC, dmp_LC, dmp_ground_LC, dmp_multi_deflate, dmp_inflate, dup_convert, dmp_convert, dmp_apply_pairs) from sympy.polys.densetools import ( dup_clear_denoms, dmp_clear_denoms, dup_diff, dmp_diff, dup_eval, dmp_eval, dmp_eval_in, dup_trunc, dmp_ground_trunc, dup_monic, dmp_ground_monic, dup_primitive, dmp_ground_primitive, dup_extract, dmp_ground_extract) from sympy.polys.galoistools import ( gf_int, gf_crt) from sympy.polys.polyconfig import query from sympy.polys.polyerrors import ( MultivariatePolynomialError, HeuristicGCDFailed, HomomorphismFailed, NotInvertible, DomainError) def dup_half_gcdex(f, g, K): """ Half extended Euclidean algorithm in `F[x]`. Returns ``(s, h)`` such that ``h = gcd(f, g)`` and ``sf = h (mod g)``. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x = ring("x", QQ) >>> f = x4 - 2x*3 - 6x*2 + 12x + 15 >>> g = x3 + x2 - 4x - 4 >>> R.dup_half_gcdex(f, g) (-1/5x + 3/5, x + 1) """ if not K.is_Field: raise DomainError("can't compute half extended GCD over %s" % K) a, b = [K.one], [] while g: q, r = dup_div(f, g, K) f, g = g, r a, b = b, dup_sub_mul(a, q, b, K) a = dup_quo_ground(a, dup_LC(f, K), K) f = dup_monic(f, K) return a, f def dmp_half_gcdex(f, g, u, K): """ Half extended Euclidean algorithm in `F[X]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) """ if not u: return dup_half_gcdex(f, g, K) else: raise MultivariatePolynomialError(f, g) def dup_gcdex(f, g, K): """ Extended Euclidean algorithm in `F[x]`. Returns ``(s, t, h)`` such that ``h = gcd(f, g)`` and ``sf + tg = h``. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x = ring("x", QQ) >>> f = x*4 - 2x*3 - 6x*2 + 12x + 15 >>> g = x3 + x2 - 4x - 4 >>> R.dup_gcdex(f, g) (-1/5x + 3/5, 1/5x2 - 6/5x + 2, x + 1) """ s, h = dup_half_gcdex(f, g, K) F = dup_sub_mul(h, s, f, K) t = dup_quo(F, g, K) return s, t, h def dmp_gcdex(f, g, u, K): """ Extended Euclidean algorithm in `F[X]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) """ if not u: return dup_gcdex(f, g, K) else: raise MultivariatePolynomialError(f, g) def dup_invert(f, g, K): """ Compute multiplicative inverse of `f` modulo `g` in `F[x]`. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x = ring("x", QQ) >>> f = x*2 - 1 >>> g = 2x - 1 >>> h = x - 1 >>> R.dup_invert(f, g) -4/3 >>> R.dup_invert(f, h) Traceback (most recent call last): ... NotInvertible: zero divisor """ s, h = dup_half_gcdex(f, g, K) if h == [K.one]: return dup_rem(s, g, K) else: raise NotInvertible("zero divisor") def dmp_invert(f, g, u, K): """ Compute multiplicative inverse of `f` modulo `g` in `F[X]`. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x = ring("x", QQ) """ if not u: return dup_invert(f, g, K) else: raise MultivariatePolynomialError(f, g) def dup_euclidean_prs(f, g, K): """ Euclidean polynomial remainder sequence (PRS) in `K[x]`. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x = ring("x", QQ) >>> f = x8 + x6 - 3x4 - 3x*3 + 8x*2 + 2x - 5 >>> g = 3x6 + 5x*4 - 4x*2 - 9x + 21 >>> prs = R.dup_euclidean_prs(f, g) >>> prs[0] x8 + x6 - 3x4 - 3x*3 + 8x*2 + 2x - 5 >>> prs[1] 3x6 + 5x*4 - 4x*2 - 9x + 21 >>> prs[2] -5/9x4 + 1/9x*2 - 1/3 >>> prs[3] -117/25x*2 - 9x + 441/25 >>> prs[4] 233150/19773x - 102500/6591 >>> prs[5] -1288744821/543589225 """ prs = [f, g] h = dup_rem(f, g, K) while h: prs.append(h) f, g = g, h h = dup_rem(f, g, K) return prs def dmp_euclidean_prs(f, g, u, K): """ Euclidean polynomial remainder sequence (PRS) in `K[X]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) """ if not u: return dup_euclidean_prs(f, g, K) else: raise MultivariatePolynomialError(f, g) def dup_primitive_prs(f, g, K): """ Primitive polynomial remainder sequence (PRS) in `K[x]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> f = x8 + x6 - 3x*4 - 3x*3 + 8x*2 + 2x - 5 >>> g = 3x6 + 5x*4 - 4x*2 - 9x + 21 >>> prs = R.dup_primitive_prs(f, g) >>> prs[0] x8 + x6 - 3x4 - 3x*3 + 8x*2 + 2x - 5 >>> prs[1] 3x6 + 5x*4 - 4x*2 - 9x + 21 >>> prs[2] -5x4 + x2 - 3 >>> prs[3] 13x*2 + 25x - 49 >>> prs[4] 4663x - 6150 >>> prs[5] 1 """ prs = [f, g] _, h = dup_primitive(dup_prem(f, g, K), K) while h: prs.append(h) f, g = g, h _, h = dup_primitive(dup_prem(f, g, K), K) return prs def dmp_primitive_prs(f, g, u, K): """ Primitive polynomial remainder sequence (PRS) in `K[X]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) """ if not u: return dup_primitive_prs(f, g, K) else: raise MultivariatePolynomialError(f, g) def dup_inner_subresultants(f, g, K): """ Subresultant PRS algorithm in `K[x]`. Computes the subresultant polynomial remainder sequence (PRS) and the non-zero scalar subresultants of `f` and `g`. By [1] Thm. 3, these are the constants '-c' (- to optimize computation of sign). The first subdeterminant is set to 1 by convention to match the polynomial and the scalar subdeterminants. If 'deg(f) < deg(g)', the subresultants of '(g,f)' are computed. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_inner_subresultants(x2 + 1, x2 - 1) ([x2 + 1, x2 - 1, -2], [1, 1, 4]) References ========== .. [1] W.S. Brown, The Subresultant PRS Algorithm. ACM Transaction of Mathematical Software 4 (1978) 237-249 """ n = dup_degree(f) m = dup_degree(g) if n < m: f, g = g, f n, m = m, n if not f: return [], [] if not g: return [f], [K.one] R = [f, g] d = n - m b = (-K.one)(d + 1) h = dup_prem(f, g, K) h = dup_mul_ground(h, b, K) lc = dup_LC(g, K) c = lcd # Conventional first scalar subdeterminant is 1 S = [K.one, c] c = -c while h: k = dup_degree(h) R.append(h) f, g, m, d = g, h, k, m - k b = -lc cd h = dup_prem(f, g, K) h = dup_quo_ground(h, b, K) lc = dup_LC(g, K) if d > 1: # abnormal case q = c(d - 1) c = K.quo((-lc)d, q) else: c = -lc S.append(-c) return R, S def dup_subresultants(f, g, K): """ Computes subresultant PRS of two polynomials in `K[x]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_subresultants(x2 + 1, x2 - 1) [x2 + 1, x2 - 1, -2] """ return dup_inner_subresultants(f, g, K)[0] def dup_prs_resultant(f, g, K): """ Resultant algorithm in `K[x]` using subresultant PRS. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_prs_resultant(x2 + 1, x2 - 1) (4, [x2 + 1, x2 - 1, -2]) """ if not f or not g: return (K.zero, []) R, S = dup_inner_subresultants(f, g, K) if dup_degree(R[-1]) > 0: return (K.zero, R) return S[-1], R def dup_resultant(f, g, K, includePRS=False): """ Computes resultant of two polynomials in `K[x]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_resultant(x2 + 1, x*2 - 1) 4 """ if includePRS: return dup_prs_resultant(f, g, K) return dup_prs_resultant(f, g, K)[0] def dmp_inner_subresultants(f, g, u, K): """ Subresultant PRS algorithm in `K[X]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = 3x*2y - y3 - 4 >>> g = x2 + xy3 - 9 >>> a = 3xy4 + y3 - 27y + 4 >>> b = -3y10 - 12y7 + y6 - 54y4 + 8y*3 + 729y*2 - 216y + 16 >>> prs = [f, g, a, b] >>> sres = [[1], [1], [3, 0, 0, 0, 0], [-3, 0, 0, -12, 1, 0, -54, 8, 729, -216, 16]] >>> R.dmp_inner_subresultants(f, g) == (prs, sres) True """ if not u: return dup_inner_subresultants(f, g, K) n = dmp_degree(f, u) m = dmp_degree(g, u) if n < m: f, g = g, f n, m = m, n if dmp_zero_p(f, u): return [], [] v = u - 1 if dmp_zero_p(g, u): return [f], [dmp_ground(K.one, v)] R = [f, g] d = n - m b = dmp_pow(dmp_ground(-K.one, v), d + 1, v, K) h = dmp_prem(f, g, u, K) h = dmp_mul_term(h, b, 0, u, K) lc = dmp_LC(g, K) c = dmp_pow(lc, d, v, K) S = [dmp_ground(K.one, v), c] c = dmp_neg(c, v, K) while not dmp_zero_p(h, u): k = dmp_degree(h, u) R.append(h) f, g, m, d = g, h, k, m - k b = dmp_mul(dmp_neg(lc, v, K), dmp_pow(c, d, v, K), v, K) h = dmp_prem(f, g, u, K) h = [ dmp_quo(ch, b, v, K) for ch in h ] lc = dmp_LC(g, K) if d > 1: p = dmp_pow(dmp_neg(lc, v, K), d, v, K) q = dmp_pow(c, d - 1, v, K) c = dmp_quo(p, q, v, K) else: c = dmp_neg(lc, v, K) S.append(dmp_neg(c, v, K)) return R, S def dmp_subresultants(f, g, u, K): """ Computes subresultant PRS of two polynomials in `K[X]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = 3x2y - y3 - 4 >>> g = x2 + xy3 - 9 >>> a = 3xy4 + y3 - 27y + 4 >>> b = -3y10 - 12y7 + y6 - 54y4 + 8y*3 + 729y*2 - 216y + 16 >>> R.dmp_subresultants(f, g) == [f, g, a, b] True """ return dmp_inner_subresultants(f, g, u, K)[0] def dmp_prs_resultant(f, g, u, K): """ Resultant algorithm in `K[X]` using subresultant PRS. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = 3x2y - y3 - 4 >>> g = x2 + xy3 - 9 >>> a = 3xy4 + y3 - 27y + 4 >>> b = -3y10 - 12y7 + y6 - 54y4 + 8y*3 + 729y*2 - 216y + 16 >>> res, prs = R.dmp_prs_resultant(f, g) >>> res == b # resultant has n-1 variables False >>> res == b.drop(x) True >>> prs == [f, g, a, b] True """ if not u: return dup_prs_resultant(f, g, K) if dmp_zero_p(f, u) or dmp_zero_p(g, u): return (dmp_zero(u - 1), []) R, S = dmp_inner_subresultants(f, g, u, K) if dmp_degree(R[-1], u) > 0: return (dmp_zero(u - 1), R) return S[-1], R def dmp_zz_modular_resultant(f, g, p, u, K): """ Compute resultant of `f` and `g` modulo a prime `p`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = x + y + 2 >>> g = 2xy + x + 3 >>> R.dmp_zz_modular_resultant(f, g, 5) -2y2 + 1 """ if not u: return gf_int(dup_prs_resultant(f, g, K)[0] % p, p) v = u - 1 n = dmp_degree(f, u) m = dmp_degree(g, u) N = dmp_degree_in(f, 1, u) M = dmp_degree_in(g, 1, u) B = nM + mN D, a = [K.one], -K.one r = dmp_zero(v) while dup_degree(D) <= B: while True: a += K.one if a == p: raise HomomorphismFailed('no luck') F = dmp_eval_in(f, gf_int(a, p), 1, u, K) if dmp_degree(F, v) == n: G = dmp_eval_in(g, gf_int(a, p), 1, u, K) if dmp_degree(G, v) == m: break R = dmp_zz_modular_resultant(F, G, p, v, K) e = dmp_eval(r, a, v, K) if not v: R = dup_strip([R]) e = dup_strip([e]) else: R = [R] e = [e] d = K.invert(dup_eval(D, a, K), p) d = dup_mul_ground(D, d, K) d = dmp_raise(d, v, 0, K) c = dmp_mul(d, dmp_sub(R, e, v, K), v, K) r = dmp_add(r, c, v, K) r = dmp_ground_trunc(r, p, v, K) D = dup_mul(D, [K.one, -a], K) D = dup_trunc(D, p, K) return r def _collins_crt(r, R, P, p, K): """Wrapper of CRT for Collins's resultant algorithm. """ return gf_int(gf_crt([r, R], [P, p], K), Pp) def dmp_zz_collins_resultant(f, g, u, K): """ Collins's modular resultant algorithm in `Z[X]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = x + y + 2 >>> g = 2xy + x + 3 >>> R.dmp_zz_collins_resultant(f, g) -2y2 - 5y + 1 """ n = dmp_degree(f, u) m = dmp_degree(g, u) if n < 0 or m < 0: return dmp_zero(u - 1) A = dmp_max_norm(f, u, K) B = dmp_max_norm(g, u, K) a = dmp_ground_LC(f, u, K) b = dmp_ground_LC(g, u, K) v = u - 1 B = K(2)K.factorial(K(n + m))A*mB*n r, p, P = dmp_zero(v), K.one, K.one while P <= B: p = K(nextprime(p)) while not (a % p) or not (b % p): p = K(nextprime(p)) F = dmp_ground_trunc(f, p, u, K) G = dmp_ground_trunc(g, p, u, K) try: R = dmp_zz_modular_resultant(F, G, p, u, K) except HomomorphismFailed: continue if K.is_one(P): r = R else: r = dmp_apply_pairs(r, R, _collins_crt, (P, p, K), v, K) P = p return r def dmp_qq_collins_resultant(f, g, u, K0): """ Collins's modular resultant algorithm in `Q[X]`. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x,y = ring("x,y", QQ) >>> f = QQ(1,2)x + y + QQ(2,3) >>> g = 2xy + x + 3 >>> R.dmp_qq_collins_resultant(f, g) -2y*2 - 7/3y + 5/6 """ n = dmp_degree(f, u) m = dmp_degree(g, u) if n < 0 or m < 0: return dmp_zero(u - 1) K1 = K0.get_ring() cf, f = dmp_clear_denoms(f, u, K0, K1) cg, g = dmp_clear_denoms(g, u, K0, K1) f = dmp_convert(f, u, K0, K1) g = dmp_convert(g, u, K0, K1) r = dmp_zz_collins_resultant(f, g, u, K1) r = dmp_convert(r, u - 1, K1, K0) c = K0.convert(cf*m cg*n, K1) return dmp_quo_ground(r, c, u - 1, K0) def dmp_resultant(f, g, u, K, includePRS=False): """ Computes resultant of two polynomials in `K[X]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = 3x*2y - y3 - 4 >>> g = x2 + xy3 - 9 >>> R.dmp_resultant(f, g) -3y*10 - 12y7 + y6 - 54y4 + 8y*3 + 729y*2 - 216y + 16 """ if not u: return dup_resultant(f, g, K, includePRS=includePRS) if includePRS: return dmp_prs_resultant(f, g, u, K) if K.is_Field: if K.is_QQ and query('USE_COLLINS_RESULTANT'): return dmp_qq_collins_resultant(f, g, u, K) else: if K.is_ZZ and query('USE_COLLINS_RESULTANT'): return dmp_zz_collins_resultant(f, g, u, K) return dmp_prs_resultant(f, g, u, K)[0] def dup_discriminant(f, K): """ Computes discriminant of a polynomial in `K[x]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_discriminant(x*2 + 2x + 3) -8 """ d = dup_degree(f) if d <= 0: return K.zero else: s = (-1)*((d(d - 1)) // 2) c = dup_LC(f, K) r = dup_resultant(f, dup_diff(f, 1, K), K) return K.quo(r, cK(s)) def dmp_discriminant(f, u, K): """ Computes discriminant of a polynomial in `K[X]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y,z,t = ring("x,y,z,t", ZZ) >>> R.dmp_discriminant(x2y + xz + t) -4yt + z2 """ if not u: return dup_discriminant(f, K) d, v = dmp_degree(f, u), u - 1 if d <= 0: return dmp_zero(v) else: s = (-1)((d(d - 1)) // 2) c = dmp_LC(f, K) r = dmp_resultant(f, dmp_diff(f, 1, u, K), u, K) c = dmp_mul_ground(c, K(s), v, K) return dmp_quo(r, c, v, K) def _dup_rr_trivial_gcd(f, g, K): """Handle trivial cases in GCD algorithm over a ring. """ if not (f or g): return [], [], [] elif not f: if K.is_nonnegative(dup_LC(g, K)): return g, [], [K.one] else: return dup_neg(g, K), [], [-K.one] elif not g: if K.is_nonnegative(dup_LC(f, K)): return f, [K.one], [] else: return dup_neg(f, K), [-K.one], [] return None def _dup_ff_trivial_gcd(f, g, K): """Handle trivial cases in GCD algorithm over a field. """ if not (f or g): return [], [], [] elif not f: return dup_monic(g, K), [], [dup_LC(g, K)] elif not g: return dup_monic(f, K), [dup_LC(f, K)], [] else: return None def _dmp_rr_trivial_gcd(f, g, u, K): """Handle trivial cases in GCD algorithm over a ring. """ zero_f = dmp_zero_p(f, u) zero_g = dmp_zero_p(g, u) if_contain_one = dmp_one_p(f, u, K) or dmp_one_p(g, u, K) if zero_f and zero_g: return tuple(dmp_zeros(3, u, K)) elif zero_f: if K.is_nonnegative(dmp_ground_LC(g, u, K)): return g, dmp_zero(u), dmp_one(u, K) else: return dmp_neg(g, u, K), dmp_zero(u), dmp_ground(-K.one, u) elif zero_g: if K.is_nonnegative(dmp_ground_LC(f, u, K)): return f, dmp_one(u, K), dmp_zero(u) else: return dmp_neg(f, u, K), dmp_ground(-K.one, u), dmp_zero(u) elif if_contain_one: return dmp_one(u, K), f, g elif query('USE_SIMPLIFY_GCD'): return _dmp_simplify_gcd(f, g, u, K) else: return None def _dmp_ff_trivial_gcd(f, g, u, K): """Handle trivial cases in GCD algorithm over a field. """ zero_f = dmp_zero_p(f, u) zero_g = dmp_zero_p(g, u) if zero_f and zero_g: return tuple(dmp_zeros(3, u, K)) elif zero_f: return (dmp_ground_monic(g, u, K), dmp_zero(u), dmp_ground(dmp_ground_LC(g, u, K), u)) elif zero_g: return (dmp_ground_monic(f, u, K), dmp_ground(dmp_ground_LC(f, u, K), u), dmp_zero(u)) elif query('USE_SIMPLIFY_GCD'): return _dmp_simplify_gcd(f, g, u, K) else: return None def _dmp_simplify_gcd(f, g, u, K): """Try to eliminate `x_0` from GCD computation in `K[X]`. """ df = dmp_degree(f, u) dg = dmp_degree(g, u) if df > 0 and dg > 0: return None if not (df or dg): F = dmp_LC(f, K) G = dmp_LC(g, K) else: if not df: F = dmp_LC(f, K) G = dmp_content(g, u, K) else: F = dmp_content(f, u, K) G = dmp_LC(g, K) v = u - 1 h = dmp_gcd(F, G, v, K) cff = [ dmp_quo(cf, h, v, K) for cf in f ] cfg = [ dmp_quo(cg, h, v, K) for cg in g ] return [h], cff, cfg def dup_rr_prs_gcd(f, g, K): """ Computes polynomial GCD using subresultants over a ring. Returns ``(h, cff, cfg)`` such that ``a = gcd(f, g)``, ``cff = quo(f, h)``, and ``cfg = quo(g, h)``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_rr_prs_gcd(x2 - 1, x2 - 3x + 2) (x - 1, x + 1, x - 2) """ result = _dup_rr_trivial_gcd(f, g, K) if result is not None: return result fc, F = dup_primitive(f, K) gc, G = dup_primitive(g, K) c = K.gcd(fc, gc) h = dup_subresultants(F, G, K)[-1] _, h = dup_primitive(h, K) if K.is_negative(dup_LC(h, K)): c = -c h = dup_mul_ground(h, c, K) cff = dup_quo(f, h, K) cfg = dup_quo(g, h, K) return h, cff, cfg def dup_ff_prs_gcd(f, g, K): """ Computes polynomial GCD using subresultants over a field. Returns ``(h, cff, cfg)`` such that ``a = gcd(f, g)``, ``cff = quo(f, h)``, and ``cfg = quo(g, h)``. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x = ring("x", QQ) >>> R.dup_ff_prs_gcd(x2 - 1, x2 - 3x + 2) (x - 1, x + 1, x - 2) """ result = _dup_ff_trivial_gcd(f, g, K) if result is not None: return result h = dup_subresultants(f, g, K)[-1] h = dup_monic(h, K) cff = dup_quo(f, h, K) cfg = dup_quo(g, h, K) return h, cff, cfg def dmp_rr_prs_gcd(f, g, u, K): """ Computes polynomial GCD using subresultants over a ring. Returns ``(h, cff, cfg)`` such that ``a = gcd(f, g)``, ``cff = quo(f, h)``, and ``cfg = quo(g, h)``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y, = ring("x,y", ZZ) >>> f = x*2 + 2xy + y2 >>> g = x2 + xy >>> R.dmp_rr_prs_gcd(f, g) (x + y, x + y, x) """ if not u: return dup_rr_prs_gcd(f, g, K) result = _dmp_rr_trivial_gcd(f, g, u, K) if result is not None: return result fc, F = dmp_primitive(f, u, K) gc, G = dmp_primitive(g, u, K) h = dmp_subresultants(F, G, u, K)[-1] c, _, _ = dmp_rr_prs_gcd(fc, gc, u - 1, K) if K.is_negative(dmp_ground_LC(h, u, K)): h = dmp_neg(h, u, K) _, h = dmp_primitive(h, u, K) h = dmp_mul_term(h, c, 0, u, K) cff = dmp_quo(f, h, u, K) cfg = dmp_quo(g, h, u, K) return h, cff, cfg def dmp_ff_prs_gcd(f, g, u, K): """ Computes polynomial GCD using subresultants over a field. Returns ``(h, cff, cfg)`` such that ``a = gcd(f, g)``, ``cff = quo(f, h)``, and ``cfg = quo(g, h)``. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x,y, = ring("x,y", QQ) >>> f = QQ(1,2)x2 + xy + QQ(1,2)y2 >>> g = x2 + xy >>> R.dmp_ff_prs_gcd(f, g) (x + y, 1/2x + 1/2y, x) """ if not u: return dup_ff_prs_gcd(f, g, K) result = _dmp_ff_trivial_gcd(f, g, u, K) if result is not None: return result fc, F = dmp_primitive(f, u, K) gc, G = dmp_primitive(g, u, K) h = dmp_subresultants(F, G, u, K)[-1] c, _, _ = dmp_ff_prs_gcd(fc, gc, u - 1, K) _, h = dmp_primitive(h, u, K) h = dmp_mul_term(h, c, 0, u, K) h = dmp_ground_monic(h, u, K) cff = dmp_quo(f, h, u, K) cfg = dmp_quo(g, h, u, K) return h, cff, cfg HEU_GCD_MAX = 6 def _dup_zz_gcd_interpolate(h, x, K): """Interpolate polynomial GCD from integer GCD. """ f = [] while h: g = h % x if g > x // 2: g -= x f.insert(0, g) h = (h - g) // x return f def dup_zz_heu_gcd(f, g, K): """ Heuristic polynomial GCD in `Z[x]`. Given univariate polynomials `f` and `g` in `Z[x]`, returns their GCD and cofactors, i.e. polynomials ``h``, ``cff`` and ``cfg`` such that:: h = gcd(f, g), cff = quo(f, h) and cfg = quo(g, h) The algorithm is purely heuristic which means it may fail to compute the GCD. This will be signaled by raising an exception. In this case you will need to switch to another GCD method. The algorithm computes the polynomial GCD by evaluating polynomials f and g at certain points and computing (fast) integer GCD of those evaluations. The polynomial GCD is recovered from the integer image by interpolation. The final step is to verify if the result is the correct GCD. This gives cofactors as a side effect. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_zz_heu_gcd(x2 - 1, x2 - 3x + 2) (x - 1, x + 1, x - 2) References ========== .. [1] [Liao95]_ """ result = _dup_rr_trivial_gcd(f, g, K) if result is not None: return result df = dup_degree(f) dg = dup_degree(g) gcd, f, g = dup_extract(f, g, K) if df == 0 or dg == 0: return [gcd], f, g f_norm = dup_max_norm(f, K) g_norm = dup_max_norm(g, K) B = K(2min(f_norm, g_norm) + 29) x = max(min(B, 99K.sqrt(B)), 2min(f_norm // abs(dup_LC(f, K)), g_norm // abs(dup_LC(g, K))) + 2) for i in range(0, HEU_GCD_MAX): ff = dup_eval(f, x, K) gg = dup_eval(g, x, K) if ff and gg: h = K.gcd(ff, gg) cff = ff // h cfg = gg // h h = _dup_zz_gcd_interpolate(h, x, K) h = dup_primitive(h, K)[1] cff_, r = dup_div(f, h, K) if not r: cfg_, r = dup_div(g, h, K) if not r: h = dup_mul_ground(h, gcd, K) return h, cff_, cfg_ cff = _dup_zz_gcd_interpolate(cff, x, K) h, r = dup_div(f, cff, K) if not r: cfg_, r = dup_div(g, h, K) if not r: h = dup_mul_ground(h, gcd, K) return h, cff, cfg_ cfg = _dup_zz_gcd_interpolate(cfg, x, K) h, r = dup_div(g, cfg, K) if not r: cff_, r = dup_div(f, h, K) if not r: h = dup_mul_ground(h, gcd, K) return h, cff_, cfg x = 73794x K.sqrt(K.sqrt(x)) // 27011 raise HeuristicGCDFailed('no luck') def _dmp_zz_gcd_interpolate(h, x, v, K): """Interpolate polynomial GCD from integer GCD. """ f = [] while not dmp_zero_p(h, v): g = dmp_ground_trunc(h, x, v, K) f.insert(0, g) h = dmp_sub(h, g, v, K) h = dmp_quo_ground(h, x, v, K) if K.is_negative(dmp_ground_LC(f, v + 1, K)): return dmp_neg(f, v + 1, K) else: return f def dmp_zz_heu_gcd(f, g, u, K): """ Heuristic polynomial GCD in `Z[X]`. Given univariate polynomials `f` and `g` in `Z[X]`, returns their GCD and cofactors, i.e. polynomials ``h``, ``cff`` and ``cfg`` such that:: h = gcd(f, g), cff = quo(f, h) and cfg = quo(g, h) The algorithm is purely heuristic which means it may fail to compute the GCD. This will be signaled by raising an exception. In this case you will need to switch to another GCD method. The algorithm computes the polynomial GCD by evaluating polynomials f and g at certain points and computing (fast) integer GCD of those evaluations. The polynomial GCD is recovered from the integer image by interpolation. The evaluation process reduces f and g variable by variable into a large integer. The final step is to verify if the interpolated polynomial is the correct GCD. This gives cofactors of the input polynomials as a side effect. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y, = ring("x,y", ZZ) >>> f = x*2 + 2xy + y2 >>> g = x2 + xy >>> R.dmp_zz_heu_gcd(f, g) (x + y, x + y, x) References ========== .. [1] [Liao95]_ """ if not u: return dup_zz_heu_gcd(f, g, K) result = _dmp_rr_trivial_gcd(f, g, u, K) if result is not None: return result gcd, f, g = dmp_ground_extract(f, g, u, K) f_norm = dmp_max_norm(f, u, K) g_norm = dmp_max_norm(g, u, K) B = K(2min(f_norm, g_norm) + 29) x = max(min(B, 99K.sqrt(B)), 2min(f_norm // abs(dmp_ground_LC(f, u, K)), g_norm // abs(dmp_ground_LC(g, u, K))) + 2) for i in range(0, HEU_GCD_MAX): ff = dmp_eval(f, x, u, K) gg = dmp_eval(g, x, u, K) v = u - 1 if not (dmp_zero_p(ff, v) or dmp_zero_p(gg, v)): h, cff, cfg = dmp_zz_heu_gcd(ff, gg, v, K) h = _dmp_zz_gcd_interpolate(h, x, v, K) h = dmp_ground_primitive(h, u, K)[1] cff_, r = dmp_div(f, h, u, K) if dmp_zero_p(r, u): cfg_, r = dmp_div(g, h, u, K) if dmp_zero_p(r, u): h = dmp_mul_ground(h, gcd, u, K) return h, cff_, cfg_ cff = _dmp_zz_gcd_interpolate(cff, x, v, K) h, r = dmp_div(f, cff, u, K) if dmp_zero_p(r, u): cfg_, r = dmp_div(g, h, u, K) if dmp_zero_p(r, u): h = dmp_mul_ground(h, gcd, u, K) return h, cff, cfg_ cfg = _dmp_zz_gcd_interpolate(cfg, x, v, K) h, r = dmp_div(g, cfg, u, K) if dmp_zero_p(r, u): cff_, r = dmp_div(f, h, u, K) if dmp_zero_p(r, u): h = dmp_mul_ground(h, gcd, u, K) return h, cff_, cfg x = 73794x * K.sqrt(K.sqrt(x)) // 27011 raise HeuristicGCDFailed('no luck') def dup_qq_heu_gcd(f, g, K0): """ Heuristic polynomial GCD in `Q[x]`. Returns ``(h, cff, cfg)`` such that ``a = gcd(f, g)``, ``cff = quo(f, h)``, and ``cfg = quo(g, h)``. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x = ring("x", QQ) >>> f = QQ(1,2)x2 + QQ(7,4)x + QQ(3,2) >>> g = QQ(1,2)x2 + x >>> R.dup_qq_heu_gcd(f, g) (x + 2, 1/2x + 3/4, 1/2x) """ result = _dup_ff_trivial_gcd(f, g, K0) if result is not None: return result K1 = K0.get_ring() cf, f = dup_clear_denoms(f, K0, K1) cg, g = dup_clear_denoms(g, K0, K1) f = dup_convert(f, K0, K1) g = dup_convert(g, K0, K1) h, cff, cfg = dup_zz_heu_gcd(f, g, K1) h = dup_convert(h, K1, K0) c = dup_LC(h, K0) h = dup_monic(h, K0) cff = dup_convert(cff, K1, K0) cfg = dup_convert(cfg, K1, K0) cff = dup_mul_ground(cff, K0.quo(c, cf), K0) cfg = dup_mul_ground(cfg, K0.quo(c, cg), K0) return h, cff, cfg def dmp_qq_heu_gcd(f, g, u, K0): """ Heuristic polynomial GCD in `Q[X]`. Returns ``(h, cff, cfg)`` such that ``a = gcd(f, g)``, ``cff = quo(f, h)``, and ``cfg = quo(g, h)``. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x,y, = ring("x,y", QQ) >>> f = QQ(1,4)x*2 + xy + y*2 >>> g = QQ(1,2)x*2 + xy >>> R.dmp_qq_heu_gcd(f, g) (x + 2y, 1/4x + 1/2y, 1/2x) """ result = _dmp_ff_trivial_gcd(f, g, u, K0) if result is not None: return result K1 = K0.get_ring() cf, f = dmp_clear_denoms(f, u, K0, K1) cg, g = dmp_clear_denoms(g, u, K0, K1) f = dmp_convert(f, u, K0, K1) g = dmp_convert(g, u, K0, K1) h, cff, cfg = dmp_zz_heu_gcd(f, g, u, K1) h = dmp_convert(h, u, K1, K0) c = dmp_ground_LC(h, u, K0) h = dmp_ground_monic(h, u, K0) cff = dmp_convert(cff, u, K1, K0) cfg = dmp_convert(cfg, u, K1, K0) cff = dmp_mul_ground(cff, K0.quo(c, cf), u, K0) cfg = dmp_mul_ground(cfg, K0.quo(c, cg), u, K0) return h, cff, cfg def dup_inner_gcd(f, g, K): """ Computes polynomial GCD and cofactors of `f` and `g` in `K[x]`. Returns ``(h, cff, cfg)`` such that ``a = gcd(f, g)``, ``cff = quo(f, h)``, and ``cfg = quo(g, h)``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_inner_gcd(x2 - 1, x2 - 3x + 2) (x - 1, x + 1, x - 2) """ if not K.is_Exact: try: exact = K.get_exact() except DomainError: return [K.one], f, g f = dup_convert(f, K, exact) g = dup_convert(g, K, exact) h, cff, cfg = dup_inner_gcd(f, g, exact) h = dup_convert(h, exact, K) cff = dup_convert(cff, exact, K) cfg = dup_convert(cfg, exact, K) return h, cff, cfg elif K.is_Field: if K.is_QQ and query('USE_HEU_GCD'): try: return dup_qq_heu_gcd(f, g, K) except HeuristicGCDFailed: pass return dup_ff_prs_gcd(f, g, K) else: if K.is_ZZ and query('USE_HEU_GCD'): try: return dup_zz_heu_gcd(f, g, K) except HeuristicGCDFailed: pass return dup_rr_prs_gcd(f, g, K) def _dmp_inner_gcd(f, g, u, K): """Helper function for `dmp_inner_gcd()`. """ if not K.is_Exact: try: exact = K.get_exact() except DomainError: return dmp_one(u, K), f, g f = dmp_convert(f, u, K, exact) g = dmp_convert(g, u, K, exact) h, cff, cfg = _dmp_inner_gcd(f, g, u, exact) h = dmp_convert(h, u, exact, K) cff = dmp_convert(cff, u, exact, K) cfg = dmp_convert(cfg, u, exact, K) return h, cff, cfg elif K.is_Field: if K.is_QQ and query('USE_HEU_GCD'): try: return dmp_qq_heu_gcd(f, g, u, K) except HeuristicGCDFailed: pass return dmp_ff_prs_gcd(f, g, u, K) else: if K.is_ZZ and query('USE_HEU_GCD'): try: return dmp_zz_heu_gcd(f, g, u, K) except HeuristicGCDFailed: pass return dmp_rr_prs_gcd(f, g, u, K) def dmp_inner_gcd(f, g, u, K): """ Computes polynomial GCD and cofactors of `f` and `g` in `K[X]`. Returns ``(h, cff, cfg)`` such that ``a = gcd(f, g)``, ``cff = quo(f, h)``, and ``cfg = quo(g, h)``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y, = ring("x,y", ZZ) >>> f = x2 + 2xy + y2 >>> g = x2 + xy >>> R.dmp_inner_gcd(f, g) (x + y, x + y, x) """ if not u: return dup_inner_gcd(f, g, K) J, (f, g) = dmp_multi_deflate((f, g), u, K) h, cff, cfg = _dmp_inner_gcd(f, g, u, K) return (dmp_inflate(h, J, u, K), dmp_inflate(cff, J, u, K), dmp_inflate(cfg, J, u, K)) def dup_gcd(f, g, K): """ Computes polynomial GCD of `f` and `g` in `K[x]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_gcd(x2 - 1, x2 - 3x + 2) x - 1 """ return dup_inner_gcd(f, g, K)[0] def dmp_gcd(f, g, u, K): """ Computes polynomial GCD of `f` and `g` in `K[X]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y, = ring("x,y", ZZ) >>> f = x2 + 2xy + y2 >>> g = x2 + xy >>> R.dmp_gcd(f, g) x + y """ return dmp_inner_gcd(f, g, u, K)[0] def dup_rr_lcm(f, g, K): """ Computes polynomial LCM over a ring in `K[x]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_rr_lcm(x2 - 1, x2 - 3x + 2) x3 - 2x*2 - x + 2 """ fc, f = dup_primitive(f, K) gc, g = dup_primitive(g, K) c = K.lcm(fc, gc) h = dup_quo(dup_mul(f, g, K), dup_gcd(f, g, K), K) return dup_mul_ground(h, c, K) def dup_ff_lcm(f, g, K): """ Computes polynomial LCM over a field in `K[x]`. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x = ring("x", QQ) >>> f = QQ(1,2)x*2 + QQ(7,4)x + QQ(3,2) >>> g = QQ(1,2)x2 + x >>> R.dup_ff_lcm(f, g) x3 + 7/2x*2 + 3x """ h = dup_quo(dup_mul(f, g, K), dup_gcd(f, g, K), K) return dup_monic(h, K) def dup_lcm(f, g, K): """ Computes polynomial LCM of `f` and `g` in `K[x]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_lcm(x2 - 1, x2 - 3x + 2) x3 - 2x2 - x + 2 """ if K.is_Field: return dup_ff_lcm(f, g, K) else: return dup_rr_lcm(f, g, K) def dmp_rr_lcm(f, g, u, K): """ Computes polynomial LCM over a ring in `K[X]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y, = ring("x,y", ZZ) >>> f = x2 + 2xy + y2 >>> g = x2 + xy >>> R.dmp_rr_lcm(f, g) x3 + 2x*2y + xy2 """ fc, f = dmp_ground_primitive(f, u, K) gc, g = dmp_ground_primitive(g, u, K) c = K.lcm(fc, gc) h = dmp_quo(dmp_mul(f, g, u, K), dmp_gcd(f, g, u, K), u, K) return dmp_mul_ground(h, c, u, K) def dmp_ff_lcm(f, g, u, K): """ Computes polynomial LCM over a field in `K[X]`. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x,y, = ring("x,y", QQ) >>> f = QQ(1,4)x*2 + xy + y*2 >>> g = QQ(1,2)x*2 + xy >>> R.dmp_ff_lcm(f, g) x*3 + 4x*2y + 4xy2 """ h = dmp_quo(dmp_mul(f, g, u, K), dmp_gcd(f, g, u, K), u, K) return dmp_ground_monic(h, u, K) def dmp_lcm(f, g, u, K): """ Computes polynomial LCM of `f` and `g` in `K[X]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y, = ring("x,y", ZZ) >>> f = x2 + 2xy + y2 >>> g = x2 + xy >>> R.dmp_lcm(f, g) x3 + 2x*2y + xy2 """ if not u: return dup_lcm(f, g, K) if K.is_Field: return dmp_ff_lcm(f, g, u, K) else: return dmp_rr_lcm(f, g, u, K) def dmp_content(f, u, K): """ Returns GCD of multivariate coefficients. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y, = ring("x,y", ZZ) >>> R.dmp_content(2xy + 6x + 4y + 12) 2y + 6 """ cont, v = dmp_LC(f, K), u - 1 if dmp_zero_p(f, u): return cont for c in f[1:]: cont = dmp_gcd(cont, c, v, K) if dmp_one_p(cont, v, K): break if K.is_negative(dmp_ground_LC(cont, v, K)): return dmp_neg(cont, v, K) else: return cont def dmp_primitive(f, u, K): """ Returns multivariate content and a primitive polynomial. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y, = ring("x,y", ZZ) >>> R.dmp_primitive(2xy + 6x + 4y + 12) (2y + 6, x + 2) """ cont, v = dmp_content(f, u, K), u - 1 if dmp_zero_p(f, u) or dmp_one_p(cont, v, K): return cont, f else: return cont, [ dmp_quo(c, cont, v, K) for c in f ] def dup_cancel(f, g, K, include=True): """ Cancel common factors in a rational function `f/g`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_cancel(2x2 - 2, x2 - 2x + 1) (2x + 2, x - 1) """ return dmp_cancel(f, g, 0, K, include=include) def dmp_cancel(f, g, u, K, include=True): """ Cancel common factors in a rational function `f/g`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_cancel(2x2 - 2, x2 - 2x + 1) (2*x + 2, x - 1) """ K0 = None if K.is_Field and K.has_assoc_Ring: K0, K = K, K.get_ring() cq, f = dmp_clear_denoms(f, u, K0, K, convert=True) cp, g = dmp_clear_denoms(g, u, K0, K, convert=True) else: cp, cq = K.one, K.one _, p, q = dmp_inner_gcd(f, g, u, K) if K0 is not None: _, cp, cq = K.cofactors(cp, cq) p = dmp_convert(p, u, K, K0) q = dmp_convert(q, u, K, K0) K = K0 p_neg = K.is_negative(dmp_ground_LC(p, u, K)) q_neg = K.is_negative(dmp_ground_LC(q, u, K)) if p_neg and q_neg: p, q = dmp_neg(p, u, K), dmp_neg(q, u, K) elif p_neg: cp, p = -cp, dmp_neg(p, u, K) elif q_neg: cp, q = -cp, dmp_neg(q, u, K) if not include: return cp, cq, p, q p = dmp_mul_ground(p, cp, u, K) q = dmp_mul_ground(q, cq, u, K) return p, q
b858624d0c0075f11c4b91f0fc82ac946cb8773cf3553b007dcdd698ea1317cb	"""Tools for constructing domains for expressions. """ from __future__ import print_function, division from sympy.core import sympify from sympy.polys.domains import ZZ, QQ, EX from sympy.polys.domains.realfield import RealField from sympy.polys.polyoptions import build_options from sympy.polys.polyutils import parallel_dict_from_basic from sympy.utilities import public def _construct_simple(coeffs, opt): """Handle simple domains, e.g.: ZZ, QQ, RR and algebraic domains. """ result, rationals, reals, algebraics = {}, False, False, False if opt.extension is True: is_algebraic = lambda coeff: coeff.is_number and coeff.is_algebraic else: is_algebraic = lambda coeff: False # XXX: add support for a + bI coefficients for coeff in coeffs: if coeff.is_Rational: if not coeff.is_Integer: rationals = True elif coeff.is_Float: if not algebraics: reals = True else: # there are both reals and algebraics -> EX return False elif is_algebraic(coeff): if not reals: algebraics = True else: # there are both algebraics and reals -> EX return False else: # this is a composite domain, e.g. ZZ[X], EX return None if algebraics: domain, result = _construct_algebraic(coeffs, opt) else: if reals: # Use the maximum precision of all coefficients for the RR's # precision max_prec = max([c._prec for c in coeffs]) domain = RealField(prec=max_prec) else: if opt.field or rationals: domain = QQ else: domain = ZZ result = [] for coeff in coeffs: result.append(domain.from_sympy(coeff)) return domain, result def _construct_algebraic(coeffs, opt): """We know that coefficients are algebraic so construct the extension. """ from sympy.polys.numberfields import primitive_element result, exts = [], set([]) for coeff in coeffs: if coeff.is_Rational: coeff = (None, 0, QQ.from_sympy(coeff)) else: a = coeff.as_coeff_add()[0] coeff -= a b = coeff.as_coeff_mul()[0] coeff /= b exts.add(coeff) a = QQ.from_sympy(a) b = QQ.from_sympy(b) coeff = (coeff, b, a) result.append(coeff) exts = list(exts) g, span, H = primitive_element(exts, ex=True, polys=True) root = sum([ sext for s, ext in zip(span, exts) ]) domain, g = QQ.algebraic_field((g, root)), g.rep.rep for i, (coeff, a, b) in enumerate(result): if coeff is not None: coeff = adomain.dtype.from_list(H[exts.index(coeff)], g, QQ) + b else: coeff = domain.dtype.from_list([b], g, QQ) result[i] = coeff return domain, result def _construct_composite(coeffs, opt): """Handle composite domains, e.g.: ZZ[X], QQ[X], ZZ(X), QQ(X). """ numers, denoms = [], [] for coeff in coeffs: numer, denom = coeff.as_numer_denom() numers.append(numer) denoms.append(denom) polys, gens = parallel_dict_from_basic(numers + denoms) # XXX: sorting if not gens: return None if opt.composite is None: if any(gen.is_number and gen.is_algebraic for gen in gens): return None # generators are number-like so lets better use EX all_symbols = set([]) for gen in gens: symbols = gen.free_symbols if all_symbols & symbols: return None # there could be algebraic relations between generators else: all_symbols \|= symbols n = len(gens) k = len(polys)//2 numers = polys[:k] denoms = polys[k:] if opt.field: fractions = True else: fractions, zeros = False, (0,)n for denom in denoms: if len(denom) > 1 or zeros not in denom: fractions = True break coeffs = set([]) if not fractions: for numer, denom in zip(numers, denoms): denom = denom[zeros] for monom, coeff in numer.items(): coeff /= denom coeffs.add(coeff) numer[monom] = coeff else: for numer, denom in zip(numers, denoms): coeffs.update(list(numer.values())) coeffs.update(list(denom.values())) rationals, reals = False, False for coeff in coeffs: if coeff.is_Rational: if not coeff.is_Integer: rationals = True elif coeff.is_Float: reals = True break if reals: max_prec = max([c._prec for c in coeffs]) ground = RealField(prec=max_prec) elif rationals: ground = QQ else: ground = ZZ result = [] if not fractions: domain = ground.poly_ring(gens) for numer in numers: for monom, coeff in numer.items(): numer[monom] = ground.from_sympy(coeff) result.append(domain(numer)) else: domain = ground.frac_field(gens) for numer, denom in zip(numers, denoms): for monom, coeff in numer.items(): numer[monom] = ground.from_sympy(coeff) for monom, coeff in denom.items(): denom[monom] = ground.from_sympy(coeff) result.append(domain((numer, denom))) return domain, result def _construct_expression(coeffs, opt): """The last resort case, i.e. use the expression domain. """ domain, result = EX, [] for coeff in coeffs: result.append(domain.from_sympy(coeff)) return domain, result @public def construct_domain(obj, *args): """Construct a minimal domain for the list of coefficients. """ opt = build_options(args) if hasattr(obj, '__iter__'): if isinstance(obj, dict): if not obj: monoms, coeffs = [], [] else: monoms, coeffs = list(zip(list(obj.items()))) else: coeffs = obj else: coeffs = [obj] coeffs = list(map(sympify, coeffs)) result = _construct_simple(coeffs, opt) if result is not None: if result is not False: domain, coeffs = result else: domain, coeffs = _construct_expression(coeffs, opt) else: if opt.composite is False: result = None else: result = _construct_composite(coeffs, opt) if result is not None: domain, coeffs = result else: domain, coeffs = _construct_expression(coeffs, opt) if hasattr(obj, '__iter__'): if isinstance(obj, dict): return domain, dict(list(zip(monoms, coeffs))) else: return domain, coeffs else: return domain, coeffs[0]
0cf6e79c153059c91ad77dff8e2fc98ee8b01cb8594d0e9efe20326092fa6793	"""Polynomial factorization routines in characteristic zero. """ from __future__ import print_function, division from sympy.polys.galoistools import ( gf_from_int_poly, gf_to_int_poly, gf_lshift, gf_add_mul, gf_mul, gf_div, gf_rem, gf_gcdex, gf_sqf_p, gf_factor_sqf, gf_factor) from sympy.polys.densebasic import ( dup_LC, dmp_LC, dmp_ground_LC, dup_TC, dup_convert, dmp_convert, dup_degree, dmp_degree, dmp_degree_in, dmp_degree_list, dmp_from_dict, dmp_zero_p, dmp_one, dmp_nest, dmp_raise, dup_strip, dmp_ground, dup_inflate, dmp_exclude, dmp_include, dmp_inject, dmp_eject, dup_terms_gcd, dmp_terms_gcd) from sympy.polys.densearith import ( dup_neg, dmp_neg, dup_add, dmp_add, dup_sub, dmp_sub, dup_mul, dmp_mul, dup_sqr, dmp_pow, dup_div, dmp_div, dup_quo, dmp_quo, dmp_expand, dmp_add_mul, dup_sub_mul, dmp_sub_mul, dup_lshift, dup_max_norm, dmp_max_norm, dup_l1_norm, dup_mul_ground, dmp_mul_ground, dup_quo_ground, dmp_quo_ground) from sympy.polys.densetools import ( dup_clear_denoms, dmp_clear_denoms, dup_trunc, dmp_ground_trunc, dup_content, dup_monic, dmp_ground_monic, dup_primitive, dmp_ground_primitive, dmp_eval_tail, dmp_eval_in, dmp_diff_eval_in, dmp_compose, dup_shift, dup_mirror) from sympy.polys.euclidtools import ( dmp_primitive, dup_inner_gcd, dmp_inner_gcd) from sympy.polys.sqfreetools import ( dup_sqf_p, dup_sqf_norm, dmp_sqf_norm, dup_sqf_part, dmp_sqf_part) from sympy.polys.polyutils import _sort_factors from sympy.polys.polyconfig import query from sympy.polys.polyerrors import ( ExtraneousFactors, DomainError, CoercionFailed, EvaluationFailed) from sympy.ntheory import nextprime, isprime, factorint from sympy.utilities import subsets from math import ceil as _ceil, log as _log from sympy.core.compatibility import range def dup_trial_division(f, factors, K): """Determine multiplicities of factors using trial division. """ result = [] for factor in factors: k = 0 while True: q, r = dup_div(f, factor, K) if not r: f, k = q, k + 1 else: break result.append((factor, k)) return _sort_factors(result) def dmp_trial_division(f, factors, u, K): """Determine multiplicities of factors using trial division. """ result = [] for factor in factors: k = 0 while True: q, r = dmp_div(f, factor, u, K) if dmp_zero_p(r, u): f, k = q, k + 1 else: break result.append((factor, k)) return _sort_factors(result) def dup_zz_mignotte_bound(f, K): """Mignotte bound for univariate polynomials in `K[x]`. """ a = dup_max_norm(f, K) b = abs(dup_LC(f, K)) n = dup_degree(f) return K.sqrt(K(n + 1))2nab def dmp_zz_mignotte_bound(f, u, K): """Mignotte bound for multivariate polynomials in `K[X]`. """ a = dmp_max_norm(f, u, K) b = abs(dmp_ground_LC(f, u, K)) n = sum(dmp_degree_list(f, u)) return K.sqrt(K(n + 1))2*nab def dup_zz_hensel_step(m, f, g, h, s, t, K): """ One step in Hensel lifting in `Z[x]`. Given positive integer `m` and `Z[x]` polynomials `f`, `g`, `h`, `s` and `t` such that:: f == gh (mod m) sg + th == 1 (mod m) lc(f) is not a zero divisor (mod m) lc(h) == 1 deg(f) == deg(g) + deg(h) deg(s) < deg(h) deg(t) < deg(g) returns polynomials `G`, `H`, `S` and `T`, such that:: f == GH (mod m2) SG + TH == 1 (mod m2) References ========== .. [1] [Gathen99]_ """ M = m2 e = dup_sub_mul(f, g, h, K) e = dup_trunc(e, M, K) q, r = dup_div(dup_mul(s, e, K), h, K) q = dup_trunc(q, M, K) r = dup_trunc(r, M, K) u = dup_add(dup_mul(t, e, K), dup_mul(q, g, K), K) G = dup_trunc(dup_add(g, u, K), M, K) H = dup_trunc(dup_add(h, r, K), M, K) u = dup_add(dup_mul(s, G, K), dup_mul(t, H, K), K) b = dup_trunc(dup_sub(u, [K.one], K), M, K) c, d = dup_div(dup_mul(s, b, K), H, K) c = dup_trunc(c, M, K) d = dup_trunc(d, M, K) u = dup_add(dup_mul(t, b, K), dup_mul(c, G, K), K) S = dup_trunc(dup_sub(s, d, K), M, K) T = dup_trunc(dup_sub(t, u, K), M, K) return G, H, S, T def dup_zz_hensel_lift(p, f, f_list, l, K): """ Multifactor Hensel lifting in `Z[x]`. Given a prime `p`, polynomial `f` over `Z[x]` such that `lc(f)` is a unit modulo `p`, monic pair-wise coprime polynomials `f_i` over `Z[x]` satisfying:: f = lc(f) f_1 ... f_r (mod p) and a positive integer `l`, returns a list of monic polynomials `F_1`, `F_2`, ..., `F_r` satisfying:: f = lc(f) F_1 ... F_r (mod pl) F_i = f_i (mod p), i = 1..r References ========== .. [1] [Gathen99]_ """ r = len(f_list) lc = dup_LC(f, K) if r == 1: F = dup_mul_ground(f, K.gcdex(lc, pl)[0], K) return [ dup_trunc(F, pl, K) ] m = p k = r // 2 d = int(_ceil(_log(l, 2))) g = gf_from_int_poly([lc], p) for f_i in f_list[:k]: g = gf_mul(g, gf_from_int_poly(f_i, p), p, K) h = gf_from_int_poly(f_list[k], p) for f_i in f_list[k + 1:]: h = gf_mul(h, gf_from_int_poly(f_i, p), p, K) s, t, _ = gf_gcdex(g, h, p, K) g = gf_to_int_poly(g, p) h = gf_to_int_poly(h, p) s = gf_to_int_poly(s, p) t = gf_to_int_poly(t, p) for _ in range(1, d + 1): (g, h, s, t), m = dup_zz_hensel_step(m, f, g, h, s, t, K), m*2 return dup_zz_hensel_lift(p, g, f_list[:k], l, K) \ + dup_zz_hensel_lift(p, h, f_list[k:], l, K) def _test_pl(fc, q, pl): if q > pl // 2: q = q - pl if not q: return True return fc % q == 0 def dup_zz_zassenhaus(f, K): """Factor primitive square-free polynomials in `Z[x]`. """ n = dup_degree(f) if n == 1: return [f] fc = f[-1] A = dup_max_norm(f, K) b = dup_LC(f, K) B = int(abs(K.sqrt(K(n + 1))2*nAb)) C = int((n + 1)(2n)A(2n - 1)) gamma = int(_ceil(2_log(C, 2))) bound = int(2gamma_log(gamma)) a = [] # choose a prime number `p` such that `f` be square free in Z_p # if there are many factors in Z_p, choose among a few different `p` # the one with fewer factors for px in range(3, bound + 1): if not isprime(px) or b % px == 0: continue px = K.convert(px) F = gf_from_int_poly(f, px) if not gf_sqf_p(F, px, K): continue fsqfx = gf_factor_sqf(F, px, K)[1] a.append((px, fsqfx)) if len(fsqfx) < 15 or len(a) > 4: break p, fsqf = min(a, key=lambda x: len(x[1])) l = int(_ceil(_log(2B + 1, p))) modular = [gf_to_int_poly(ff, p) for ff in fsqf] g = dup_zz_hensel_lift(p, f, modular, l, K) sorted_T = range(len(g)) T = set(sorted_T) factors, s = [], 1 pl = p*l while 2s <= len(T): for S in subsets(sorted_T, s): # lift the constant coefficient of the product `G` of the factors # in the subset `S`; if it is does not divide `fc`, `G` does # not divide the input polynomial if b == 1: q = 1 for i in S: q = qg[i][-1] q = q % pl if not _test_pl(fc, q, pl): continue else: G = [b] for i in S: G = dup_mul(G, g[i], K) G = dup_trunc(G, pl, K) G = dup_primitive(G, K)[1] q = G[-1] if q and fc % q != 0: continue H = [b] S = set(S) T_S = T - S if b == 1: G = [b] for i in S: G = dup_mul(G, g[i], K) G = dup_trunc(G, pl, K) for i in T_S: H = dup_mul(H, g[i], K) H = dup_trunc(H, pl, K) G_norm = dup_l1_norm(G, K) H_norm = dup_l1_norm(H, K) if G_normH_norm <= B: T = T_S sorted_T = [i for i in sorted_T if i not in S] G = dup_primitive(G, K)[1] f = dup_primitive(H, K)[1] factors.append(G) b = dup_LC(f, K) break else: s += 1 return factors + [f] def dup_zz_irreducible_p(f, K): """Test irreducibility using Eisenstein's criterion. """ lc = dup_LC(f, K) tc = dup_TC(f, K) e_fc = dup_content(f[1:], K) if e_fc: e_ff = factorint(int(e_fc)) for p in e_ff.keys(): if (lc % p) and (tc % p2): return True def dup_cyclotomic_p(f, K, irreducible=False): """ Efficiently test if ``f`` is a cyclotomic polnomial. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> f = x16 + x14 - x10 + x8 - x6 + x2 + 1 >>> R.dup_cyclotomic_p(f) False >>> g = x16 + x14 - x10 - x8 - x6 + x2 + 1 >>> R.dup_cyclotomic_p(g) True """ if K.is_QQ: try: K0, K = K, K.get_ring() f = dup_convert(f, K0, K) except CoercionFailed: return False elif not K.is_ZZ: return False lc = dup_LC(f, K) tc = dup_TC(f, K) if lc != 1 or (tc != -1 and tc != 1): return False if not irreducible: coeff, factors = dup_factor_list(f, K) if coeff != K.one or factors != [(f, 1)]: return False n = dup_degree(f) g, h = [], [] for i in range(n, -1, -2): g.insert(0, f[i]) for i in range(n - 1, -1, -2): h.insert(0, f[i]) g = dup_sqr(dup_strip(g), K) h = dup_sqr(dup_strip(h), K) F = dup_sub(g, dup_lshift(h, 1, K), K) if K.is_negative(dup_LC(F, K)): F = dup_neg(F, K) if F == f: return True g = dup_mirror(f, K) if K.is_negative(dup_LC(g, K)): g = dup_neg(g, K) if F == g and dup_cyclotomic_p(g, K): return True G = dup_sqf_part(F, K) if dup_sqr(G, K) == F and dup_cyclotomic_p(G, K): return True return False def dup_zz_cyclotomic_poly(n, K): """Efficiently generate n-th cyclotomic polnomial. """ h = [K.one, -K.one] for p, k in factorint(n).items(): h = dup_quo(dup_inflate(h, p, K), h, K) h = dup_inflate(h, p(k - 1), K) return h def _dup_cyclotomic_decompose(n, K): H = [[K.one, -K.one]] for p, k in factorint(n).items(): Q = [ dup_quo(dup_inflate(h, p, K), h, K) for h in H ] H.extend(Q) for i in range(1, k): Q = [ dup_inflate(q, p, K) for q in Q ] H.extend(Q) return H def dup_zz_cyclotomic_factor(f, K): """ Efficiently factor polynomials `xn - 1` and `xn + 1` in `Z[x]`. Given a univariate polynomial `f` in `Z[x]` returns a list of factors of `f`, provided that `f` is in the form `xn - 1` or `xn + 1` for `n >= 1`. Otherwise returns None. Factorization is performed using using cyclotomic decomposition of `f`, which makes this method much faster that any other direct factorization approach (e.g. Zassenhaus's). References ========== .. [1] [Weisstein09]_ """ lc_f, tc_f = dup_LC(f, K), dup_TC(f, K) if dup_degree(f) <= 0: return None if lc_f != 1 or tc_f not in [-1, 1]: return None if any(bool(cf) for cf in f[1:-1]): return None n = dup_degree(f) F = _dup_cyclotomic_decompose(n, K) if not K.is_one(tc_f): return F else: H = [] for h in _dup_cyclotomic_decompose(2n, K): if h not in F: H.append(h) return H def dup_zz_factor_sqf(f, K): """Factor square-free (non-primitive) polyomials in `Z[x]`. """ cont, g = dup_primitive(f, K) n = dup_degree(g) if dup_LC(g, K) < 0: cont, g = -cont, dup_neg(g, K) if n <= 0: return cont, [] elif n == 1: return cont, [g] if query('USE_IRREDUCIBLE_IN_FACTOR'): if dup_zz_irreducible_p(g, K): return cont, [g] factors = None if query('USE_CYCLOTOMIC_FACTOR'): factors = dup_zz_cyclotomic_factor(g, K) if factors is None: factors = dup_zz_zassenhaus(g, K) return cont, _sort_factors(factors, multiple=False) def dup_zz_factor(f, K): """ Factor (non square-free) polynomials in `Z[x]`. Given a univariate polynomial `f` in `Z[x]` computes its complete factorization `f_1, ..., f_n` into irreducibles over integers:: f = content(f) f_1k_1 ... f_nk_n The factorization is computed by reducing the input polynomial into a primitive square-free polynomial and factoring it using Zassenhaus algorithm. Trial division is used to recover the multiplicities of factors. The result is returned as a tuple consisting of:: (content(f), [(f_1, k_1), ..., (f_n, k_n)) Examples ======== Consider the polynomial `f = 2x*4 - 2`:: >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_zz_factor(2x4 - 2) (2, [(x - 1, 1), (x + 1, 1), (x2 + 1, 1)]) In result we got the following factorization:: f = 2 (x - 1) (x + 1) (x2 + 1) Note that this is a complete factorization over integers, however over Gaussian integers we can factor the last term. By default, polynomials `xn - 1` and `x*n + 1` are factored using cyclotomic decomposition to speedup computations. To disable this behaviour set cyclotomic=False. References ========== .. [1] [Gathen99]_ """ cont, g = dup_primitive(f, K) n = dup_degree(g) if dup_LC(g, K) < 0: cont, g = -cont, dup_neg(g, K) if n <= 0: return cont, [] elif n == 1: return cont, [(g, 1)] if query('USE_IRREDUCIBLE_IN_FACTOR'): if dup_zz_irreducible_p(g, K): return cont, [(g, 1)] g = dup_sqf_part(g, K) H = None if query('USE_CYCLOTOMIC_FACTOR'): H = dup_zz_cyclotomic_factor(g, K) if H is None: H = dup_zz_zassenhaus(g, K) factors = dup_trial_division(f, H, K) return cont, factors def dmp_zz_wang_non_divisors(E, cs, ct, K): """Wang/EEZ: Compute a set of valid divisors. """ result = [ csct ] for q in E: q = abs(q) for r in reversed(result): while r != 1: r = K.gcd(r, q) q = q // r if K.is_one(q): return None result.append(q) return result[1:] def dmp_zz_wang_test_points(f, T, ct, A, u, K): """Wang/EEZ: Test evaluation points for suitability. """ if not dmp_eval_tail(dmp_LC(f, K), A, u - 1, K): raise EvaluationFailed('no luck') g = dmp_eval_tail(f, A, u, K) if not dup_sqf_p(g, K): raise EvaluationFailed('no luck') c, h = dup_primitive(g, K) if K.is_negative(dup_LC(h, K)): c, h = -c, dup_neg(h, K) v = u - 1 E = [ dmp_eval_tail(t, A, v, K) for t, _ in T ] D = dmp_zz_wang_non_divisors(E, c, ct, K) if D is not None: return c, h, E else: raise EvaluationFailed('no luck') def dmp_zz_wang_lead_coeffs(f, T, cs, E, H, A, u, K): """Wang/EEZ: Compute correct leading coefficients. """ C, J, v = [], [0]len(E), u - 1 for h in H: c = dmp_one(v, K) d = dup_LC(h, K)cs for i in reversed(range(len(E))): k, e, (t, _) = 0, E[i], T[i] while not (d % e): d, k = d//e, k + 1 if k != 0: c, J[i] = dmp_mul(c, dmp_pow(t, k, v, K), v, K), 1 C.append(c) if any(not j for j in J): raise ExtraneousFactors # pragma: no cover CC, HH = [], [] for c, h in zip(C, H): d = dmp_eval_tail(c, A, v, K) lc = dup_LC(h, K) if K.is_one(cs): cc = lc//d else: g = K.gcd(lc, d) d, cc = d//g, lc//g h, cs = dup_mul_ground(h, d, K), cs//d c = dmp_mul_ground(c, cc, v, K) CC.append(c) HH.append(h) if K.is_one(cs): return f, HH, CC CCC, HHH = [], [] for c, h in zip(CC, HH): CCC.append(dmp_mul_ground(c, cs, v, K)) HHH.append(dmp_mul_ground(h, cs, 0, K)) f = dmp_mul_ground(f, cs*(len(H) - 1), u, K) return f, HHH, CCC def dup_zz_diophantine(F, m, p, K): """Wang/EEZ: Solve univariate Diophantine equations. """ if len(F) == 2: a, b = F f = gf_from_int_poly(a, p) g = gf_from_int_poly(b, p) s, t, G = gf_gcdex(g, f, p, K) s = gf_lshift(s, m, K) t = gf_lshift(t, m, K) q, s = gf_div(s, f, p, K) t = gf_add_mul(t, q, g, p, K) s = gf_to_int_poly(s, p) t = gf_to_int_poly(t, p) result = [s, t] else: G = [F[-1]] for f in reversed(F[1:-1]): G.insert(0, dup_mul(f, G[0], K)) S, T = [], [[1]] for f, g in zip(F, G): t, s = dmp_zz_diophantine([g, f], T[-1], [], 0, p, 1, K) T.append(t) S.append(s) result, S = [], S + [T[-1]] for s, f in zip(S, F): s = gf_from_int_poly(s, p) f = gf_from_int_poly(f, p) r = gf_rem(gf_lshift(s, m, K), f, p, K) s = gf_to_int_poly(r, p) result.append(s) return result def dmp_zz_diophantine(F, c, A, d, p, u, K): """Wang/EEZ: Solve multivariate Diophantine equations. """ if not A: S = [ [] for _ in F ] n = dup_degree(c) for i, coeff in enumerate(c): if not coeff: continue T = dup_zz_diophantine(F, n - i, p, K) for j, (s, t) in enumerate(zip(S, T)): t = dup_mul_ground(t, coeff, K) S[j] = dup_trunc(dup_add(s, t, K), p, K) else: n = len(A) e = dmp_expand(F, u, K) a, A = A[-1], A[:-1] B, G = [], [] for f in F: B.append(dmp_quo(e, f, u, K)) G.append(dmp_eval_in(f, a, n, u, K)) C = dmp_eval_in(c, a, n, u, K) v = u - 1 S = dmp_zz_diophantine(G, C, A, d, p, v, K) S = [ dmp_raise(s, 1, v, K) for s in S ] for s, b in zip(S, B): c = dmp_sub_mul(c, s, b, u, K) c = dmp_ground_trunc(c, p, u, K) m = dmp_nest([K.one, -a], n, K) M = dmp_one(n, K) for k in K.map(range(0, d)): if dmp_zero_p(c, u): break M = dmp_mul(M, m, u, K) C = dmp_diff_eval_in(c, k + 1, a, n, u, K) if not dmp_zero_p(C, v): C = dmp_quo_ground(C, K.factorial(k + 1), v, K) T = dmp_zz_diophantine(G, C, A, d, p, v, K) for i, t in enumerate(T): T[i] = dmp_mul(dmp_raise(t, 1, v, K), M, u, K) for i, (s, t) in enumerate(zip(S, T)): S[i] = dmp_add(s, t, u, K) for t, b in zip(T, B): c = dmp_sub_mul(c, t, b, u, K) c = dmp_ground_trunc(c, p, u, K) S = [ dmp_ground_trunc(s, p, u, K) for s in S ] return S def dmp_zz_wang_hensel_lifting(f, H, LC, A, p, u, K): """Wang/EEZ: Parallel Hensel lifting algorithm. """ S, n, v = [f], len(A), u - 1 H = list(H) for i, a in enumerate(reversed(A[1:])): s = dmp_eval_in(S[0], a, n - i, u - i, K) S.insert(0, dmp_ground_trunc(s, p, v - i, K)) d = max(dmp_degree_list(f, u)[1:]) for j, s, a in zip(range(2, n + 2), S, A): G, w = list(H), j - 1 I, J = A[:j - 2], A[j - 1:] for i, (h, lc) in enumerate(zip(H, LC)): lc = dmp_ground_trunc(dmp_eval_tail(lc, J, v, K), p, w - 1, K) H[i] = [lc] + dmp_raise(h[1:], 1, w - 1, K) m = dmp_nest([K.one, -a], w, K) M = dmp_one(w, K) c = dmp_sub(s, dmp_expand(H, w, K), w, K) dj = dmp_degree_in(s, w, w) for k in K.map(range(0, dj)): if dmp_zero_p(c, w): break M = dmp_mul(M, m, w, K) C = dmp_diff_eval_in(c, k + 1, a, w, w, K) if not dmp_zero_p(C, w - 1): C = dmp_quo_ground(C, K.factorial(k + 1), w - 1, K) T = dmp_zz_diophantine(G, C, I, d, p, w - 1, K) for i, (h, t) in enumerate(zip(H, T)): h = dmp_add_mul(h, dmp_raise(t, 1, w - 1, K), M, w, K) H[i] = dmp_ground_trunc(h, p, w, K) h = dmp_sub(s, dmp_expand(H, w, K), w, K) c = dmp_ground_trunc(h, p, w, K) if dmp_expand(H, u, K) != f: raise ExtraneousFactors # pragma: no cover else: return H def dmp_zz_wang(f, u, K, mod=None, seed=None): """ Factor primitive square-free polynomials in `Z[X]`. Given a multivariate polynomial `f` in `Z[x_1,...,x_n]`, which is primitive and square-free in `x_1`, computes factorization of `f` into irreducibles over integers. The procedure is based on Wang's Enhanced Extended Zassenhaus algorithm. The algorithm works by viewing `f` as a univariate polynomial in `Z[x_2,...,x_n][x_1]`, for which an evaluation mapping is computed:: x_2 -> a_2, ..., x_n -> a_n where `a_i`, for `i = 2, ..., n`, are carefully chosen integers. The mapping is used to transform `f` into a univariate polynomial in `Z[x_1]`, which can be factored efficiently using Zassenhaus algorithm. The last step is to lift univariate factors to obtain true multivariate factors. For this purpose a parallel Hensel lifting procedure is used. The parameter ``seed`` is passed to _randint and can be used to seed randint (when an integer) or (for testing purposes) can be a sequence of numbers. References ========== .. [1] [Wang78]_ .. [2] [Geddes92]_ """ from sympy.utilities.randtest import _randint randint = _randint(seed) ct, T = dmp_zz_factor(dmp_LC(f, K), u - 1, K) b = dmp_zz_mignotte_bound(f, u, K) p = K(nextprime(b)) if mod is None: if u == 1: mod = 2 else: mod = 1 history, configs, A, r = set([]), [], [K.zero]u, None try: cs, s, E = dmp_zz_wang_test_points(f, T, ct, A, u, K) _, H = dup_zz_factor_sqf(s, K) r = len(H) if r == 1: return [f] configs = [(s, cs, E, H, A)] except EvaluationFailed: pass eez_num_configs = query('EEZ_NUMBER_OF_CONFIGS') eez_num_tries = query('EEZ_NUMBER_OF_TRIES') eez_mod_step = query('EEZ_MODULUS_STEP') while len(configs) < eez_num_configs: for _ in range(eez_num_tries): A = [ K(randint(-mod, mod)) for _ in range(u) ] if tuple(A) not in history: history.add(tuple(A)) else: continue try: cs, s, E = dmp_zz_wang_test_points(f, T, ct, A, u, K) except EvaluationFailed: continue _, H = dup_zz_factor_sqf(s, K) rr = len(H) if r is not None: if rr != r: # pragma: no cover if rr < r: configs, r = [], rr else: continue else: r = rr if r == 1: return [f] configs.append((s, cs, E, H, A)) if len(configs) == eez_num_configs: break else: mod += eez_mod_step s_norm, s_arg, i = None, 0, 0 for s, _, _, _, _ in configs: _s_norm = dup_max_norm(s, K) if s_norm is not None: if _s_norm < s_norm: s_norm = _s_norm s_arg = i else: s_norm = _s_norm i += 1 _, cs, E, H, A = configs[s_arg] orig_f = f try: f, H, LC = dmp_zz_wang_lead_coeffs(f, T, cs, E, H, A, u, K) factors = dmp_zz_wang_hensel_lifting(f, H, LC, A, p, u, K) except ExtraneousFactors: # pragma: no cover if query('EEZ_RESTART_IF_NEEDED'): return dmp_zz_wang(orig_f, u, K, mod + 1) else: raise ExtraneousFactors( "we need to restart algorithm with better parameters") result = [] for f in factors: _, f = dmp_ground_primitive(f, u, K) if K.is_negative(dmp_ground_LC(f, u, K)): f = dmp_neg(f, u, K) result.append(f) return result def dmp_zz_factor(f, u, K): """ Factor (non square-free) polynomials in `Z[X]`. Given a multivariate polynomial `f` in `Z[x]` computes its complete factorization `f_1, ..., f_n` into irreducibles over integers:: f = content(f) f_1k_1 ... f_nk_n The factorization is computed by reducing the input polynomial into a primitive square-free polynomial and factoring it using Enhanced Extended Zassenhaus (EEZ) algorithm. Trial division is used to recover the multiplicities of factors. The result is returned as a tuple consisting of:: (content(f), [(f_1, k_1), ..., (f_n, k_n)) Consider polynomial `f = 2(x2 - y2)`:: >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_zz_factor(2x*2 - 2y*2) (2, [(x - y, 1), (x + y, 1)]) In result we got the following factorization:: f = 2 (x - y) (x + y) References ========== .. [1] [Gathen99]_ """ if not u: return dup_zz_factor(f, K) if dmp_zero_p(f, u): return K.zero, [] cont, g = dmp_ground_primitive(f, u, K) if dmp_ground_LC(g, u, K) < 0: cont, g = -cont, dmp_neg(g, u, K) if all(d <= 0 for d in dmp_degree_list(g, u)): return cont, [] G, g = dmp_primitive(g, u, K) factors = [] if dmp_degree(g, u) > 0: g = dmp_sqf_part(g, u, K) H = dmp_zz_wang(g, u, K) factors = dmp_trial_division(f, H, u, K) for g, k in dmp_zz_factor(G, u - 1, K)[1]: factors.insert(0, ([g], k)) return cont, _sort_factors(factors) def dup_ext_factor(f, K): """Factor univariate polynomials over algebraic number fields. """ n, lc = dup_degree(f), dup_LC(f, K) f = dup_monic(f, K) if n <= 0: return lc, [] if n == 1: return lc, [(f, 1)] f, F = dup_sqf_part(f, K), f s, g, r = dup_sqf_norm(f, K) factors = dup_factor_list_include(r, K.dom) if len(factors) == 1: return lc, [(f, n//dup_degree(f))] H = sK.unit for i, (factor, _) in enumerate(factors): h = dup_convert(factor, K.dom, K) h, _, g = dup_inner_gcd(h, g, K) h = dup_shift(h, H, K) factors[i] = h factors = dup_trial_division(F, factors, K) return lc, factors def dmp_ext_factor(f, u, K): """Factor multivariate polynomials over algebraic number fields. """ if not u: return dup_ext_factor(f, K) lc = dmp_ground_LC(f, u, K) f = dmp_ground_monic(f, u, K) if all(d <= 0 for d in dmp_degree_list(f, u)): return lc, [] f, F = dmp_sqf_part(f, u, K), f s, g, r = dmp_sqf_norm(f, u, K) factors = dmp_factor_list_include(r, u, K.dom) if len(factors) == 1: factors = [f] else: H = dmp_raise([K.one, sK.unit], u, 0, K) for i, (factor, _) in enumerate(factors): h = dmp_convert(factor, u, K.dom, K) h, _, g = dmp_inner_gcd(h, g, u, K) h = dmp_compose(h, H, u, K) factors[i] = h return lc, dmp_trial_division(F, factors, u, K) def dup_gf_factor(f, K): """Factor univariate polynomials over finite fields. """ f = dup_convert(f, K, K.dom) coeff, factors = gf_factor(f, K.mod, K.dom) for i, (f, k) in enumerate(factors): factors[i] = (dup_convert(f, K.dom, K), k) return K.convert(coeff, K.dom), factors def dmp_gf_factor(f, u, K): """Factor multivariate polynomials over finite fields. """ raise NotImplementedError('multivariate polynomials over finite fields') def dup_factor_list(f, K0): """Factor polynomials into irreducibles in `K[x]`. """ j, f = dup_terms_gcd(f, K0) cont, f = dup_primitive(f, K0) if K0.is_FiniteField: coeff, factors = dup_gf_factor(f, K0) elif K0.is_Algebraic: coeff, factors = dup_ext_factor(f, K0) else: if not K0.is_Exact: K0_inexact, K0 = K0, K0.get_exact() f = dup_convert(f, K0_inexact, K0) else: K0_inexact = None if K0.is_Field: K = K0.get_ring() denom, f = dup_clear_denoms(f, K0, K) f = dup_convert(f, K0, K) else: K = K0 if K.is_ZZ: coeff, factors = dup_zz_factor(f, K) elif K.is_Poly: f, u = dmp_inject(f, 0, K) coeff, factors = dmp_factor_list(f, u, K.dom) for i, (f, k) in enumerate(factors): factors[i] = (dmp_eject(f, u, K), k) coeff = K.convert(coeff, K.dom) else: # pragma: no cover raise DomainError('factorization not supported over %s' % K0) if K0.is_Field: for i, (f, k) in enumerate(factors): factors[i] = (dup_convert(f, K, K0), k) coeff = K0.convert(coeff, K) coeff = K0.quo(coeff, denom) if K0_inexact: for i, (f, k) in enumerate(factors): max_norm = dup_max_norm(f, K0) f = dup_quo_ground(f, max_norm, K0) f = dup_convert(f, K0, K0_inexact) factors[i] = (f, k) coeff = K0.mul(coeff, K0.pow(max_norm, k)) coeff = K0_inexact.convert(coeff, K0) K0 = K0_inexact if j: factors.insert(0, ([K0.one, K0.zero], j)) return coeffcont, _sort_factors(factors) def dup_factor_list_include(f, K): """Factor polynomials into irreducibles in `K[x]`. """ coeff, factors = dup_factor_list(f, K) if not factors: return [(dup_strip([coeff]), 1)] else: g = dup_mul_ground(factors[0][0], coeff, K) return [(g, factors[0][1])] + factors[1:] def dmp_factor_list(f, u, K0): """Factor polynomials into irreducibles in `K[X]`. """ if not u: return dup_factor_list(f, K0) J, f = dmp_terms_gcd(f, u, K0) cont, f = dmp_ground_primitive(f, u, K0) if K0.is_FiniteField: # pragma: no cover coeff, factors = dmp_gf_factor(f, u, K0) elif K0.is_Algebraic: coeff, factors = dmp_ext_factor(f, u, K0) else: if not K0.is_Exact: K0_inexact, K0 = K0, K0.get_exact() f = dmp_convert(f, u, K0_inexact, K0) else: K0_inexact = None if K0.is_Field: K = K0.get_ring() denom, f = dmp_clear_denoms(f, u, K0, K) f = dmp_convert(f, u, K0, K) else: K = K0 if K.is_ZZ: levels, f, v = dmp_exclude(f, u, K) coeff, factors = dmp_zz_factor(f, v, K) for i, (f, k) in enumerate(factors): factors[i] = (dmp_include(f, levels, v, K), k) elif K.is_Poly: f, v = dmp_inject(f, u, K) coeff, factors = dmp_factor_list(f, v, K.dom) for i, (f, k) in enumerate(factors): factors[i] = (dmp_eject(f, v, K), k) coeff = K.convert(coeff, K.dom) else: # pragma: no cover raise DomainError('factorization not supported over %s' % K0) if K0.is_Field: for i, (f, k) in enumerate(factors): factors[i] = (dmp_convert(f, u, K, K0), k) coeff = K0.convert(coeff, K) coeff = K0.quo(coeff, denom) if K0_inexact: for i, (f, k) in enumerate(factors): max_norm = dmp_max_norm(f, u, K0) f = dmp_quo_ground(f, max_norm, u, K0) f = dmp_convert(f, u, K0, K0_inexact) factors[i] = (f, k) coeff = K0.mul(coeff, K0.pow(max_norm, k)) coeff = K0_inexact.convert(coeff, K0) K0 = K0_inexact for i, j in enumerate(reversed(J)): if not j: continue term = {(0,)(u - i) + (1,) + (0,)i: K0.one} factors.insert(0, (dmp_from_dict(term, u, K0), j)) return coeff*cont, _sort_factors(factors) def dmp_factor_list_include(f, u, K): """Factor polynomials into irreducibles in `K[X]`. """ if not u: return dup_factor_list_include(f, K) coeff, factors = dmp_factor_list(f, u, K) if not factors: return [(dmp_ground(coeff, u), 1)] else: g = dmp_mul_ground(factors[0][0], coeff, u, K) return [(g, factors[0][1])] + factors[1:] def dup_irreducible_p(f, K): """Returns ``True`` if ``f`` has no factors over its domain. """ return dmp_irreducible_p(f, 0, K) def dmp_irreducible_p(f, u, K): """Returns ``True`` if ``f`` has no factors over its domain. """ _, factors = dmp_factor_list(f, u, K) if not factors: return True elif len(factors) > 1: return False else: _, k = factors[0] return k == 1
07b9c5abd589ce4c417f557a7308bf2c0bdbd7dda692f609fac5743f3aca3be7	r""" Sparse distributed elements of free modules over multivariate (generalized) polynomial rings. This code and its data structures are very much like the distributed polynomials, except that the first "exponent" of the monomial is a module generator index. That is, the multi-exponent ``(i, e_1, ..., e_n)`` represents the "monomial" `x_1^{e_1} \cdots x_n^{e_n} f_i` of the free module `F` generated by `f_1, \ldots, f_r` over (a localization of) the ring `K[x_1, \ldots, x_n]`. A module element is simply stored as a list of terms ordered by the monomial order. Here a term is a pair of a multi-exponent and a coefficient. In general, this coefficient should never be zero (since it can then be omitted). The zero module element is stored as an empty list. The main routines are ``sdm_nf_mora`` and ``sdm_groebner`` which can be used to compute, respectively, weak normal forms and standard bases. They work with arbitrary (not necessarily global) monomial orders. In general, product orders have to be used to construct valid monomial orders for modules. However, ``lex`` can be used as-is. Note that the "level" (number of variables, i.e. parameter u+1 in distributedpolys.py) is never needed in this code. The main reference for this file is [SCA], "A Singular Introduction to Commutative Algebra". """ from __future__ import print_function, division from itertools import permutations from sympy.polys.monomials import ( monomial_mul, monomial_lcm, monomial_div, monomial_deg ) from sympy.polys.polytools import Poly from sympy.polys.polyutils import parallel_dict_from_expr from sympy import S, sympify from sympy.core.compatibility import range # Additional monomial tools. def sdm_monomial_mul(M, X): """ Multiply tuple ``X`` representing a monomial of `K[X]` into the tuple ``M`` representing a monomial of `F`. Examples ======== Multiplying `xy^3` into `x f_1` yields `x^2 y^3 f_1`: >>> from sympy.polys.distributedmodules import sdm_monomial_mul >>> sdm_monomial_mul((1, 1, 0), (1, 3)) (1, 2, 3) """ return (M[0],) + monomial_mul(X, M[1:]) def sdm_monomial_deg(M): """ Return the total degree of ``M``. Examples ======== For example, the total degree of `x^2 y f_5` is 3: >>> from sympy.polys.distributedmodules import sdm_monomial_deg >>> sdm_monomial_deg((5, 2, 1)) 3 """ return monomial_deg(M[1:]) def sdm_monomial_lcm(A, B): r""" Return the "least common multiple" of ``A`` and ``B``. IF `A = M e_j` and `B = N e_j`, where `M` and `N` are polynomial monomials, this returns `\lcm(M, N) e_j`. Note that ``A`` and ``B`` involve distinct monomials. Otherwise the result is undefined. Examples ======== >>> from sympy.polys.distributedmodules import sdm_monomial_lcm >>> sdm_monomial_lcm((1, 2, 3), (1, 0, 5)) (1, 2, 5) """ return (A[0],) + monomial_lcm(A[1:], B[1:]) def sdm_monomial_divides(A, B): """ Does there exist a (polynomial) monomial X such that XA = B? Examples ======== Positive examples: In the following examples, the monomial is given in terms of x, y and the generator(s), f_1, f_2 etc. The tuple form of that monomial is used in the call to sdm_monomial_divides. Note: the generator appears last in the expression but first in the tuple and other factors appear in the same order that they appear in the monomial expression. `A = f_1` divides `B = f_1` >>> from sympy.polys.distributedmodules import sdm_monomial_divides >>> sdm_monomial_divides((1, 0, 0), (1, 0, 0)) True `A = f_1` divides `B = x^2 y f_1` >>> sdm_monomial_divides((1, 0, 0), (1, 2, 1)) True `A = xy f_5` divides `B = x^2 y f_5` >>> sdm_monomial_divides((5, 1, 1), (5, 2, 1)) True Negative examples: `A = f_1` does not divide `B = f_2` >>> sdm_monomial_divides((1, 0, 0), (2, 0, 0)) False `A = x f_1` does not divide `B = f_1` >>> sdm_monomial_divides((1, 1, 0), (1, 0, 0)) False `A = xy^2 f_5` does not divide `B = y f_5` >>> sdm_monomial_divides((5, 1, 2), (5, 0, 1)) False """ return A[0] == B[0] and all(a <= b for a, b in zip(A[1:], B[1:])) # The actual distributed modules code. def sdm_LC(f, K): """Returns the leading coeffcient of ``f``. """ if not f: return K.zero else: return f[0][1] def sdm_to_dict(f): """Make a dictionary from a distributed polynomial. """ return dict(f) def sdm_from_dict(d, O): """ Create an sdm from a dictionary. Here ``O`` is the monomial order to use. Examples ======== >>> from sympy.polys.distributedmodules import sdm_from_dict >>> from sympy.polys import QQ, lex >>> dic = {(1, 1, 0): QQ(1), (1, 0, 0): QQ(2), (0, 1, 0): QQ(0)} >>> sdm_from_dict(dic, lex) [((1, 1, 0), 1), ((1, 0, 0), 2)] """ return sdm_strip(sdm_sort(list(d.items()), O)) def sdm_sort(f, O): """Sort terms in ``f`` using the given monomial order ``O``. """ return sorted(f, key=lambda term: O(term[0]), reverse=True) def sdm_strip(f): """Remove terms with zero coefficients from ``f`` in ``K[X]``. """ return [ (monom, coeff) for monom, coeff in f if coeff ] def sdm_add(f, g, O, K): """ Add two module elements ``f``, ``g``. Addition is done over the ground field ``K``, monomials are ordered according to ``O``. Examples ======== All examples use lexicographic order. `(xy f_1) + (f_2) = f_2 + xy f_1` >>> from sympy.polys.distributedmodules import sdm_add >>> from sympy.polys import lex, QQ >>> sdm_add([((1, 1, 1), QQ(1))], [((2, 0, 0), QQ(1))], lex, QQ) [((2, 0, 0), 1), ((1, 1, 1), 1)] `(xy f_1) + (-xy f_1)` = 0` >>> sdm_add([((1, 1, 1), QQ(1))], [((1, 1, 1), QQ(-1))], lex, QQ) [] `(f_1) + (2f_1) = 3f_1` >>> sdm_add([((1, 0, 0), QQ(1))], [((1, 0, 0), QQ(2))], lex, QQ) [((1, 0, 0), 3)] `(yf_1) + (xf_1) = xf_1 + yf_1` >>> sdm_add([((1, 0, 1), QQ(1))], [((1, 1, 0), QQ(1))], lex, QQ) [((1, 1, 0), 1), ((1, 0, 1), 1)] """ h = dict(f) for monom, c in g: if monom in h: coeff = h[monom] + c if not coeff: del h[monom] else: h[monom] = coeff else: h[monom] = c return sdm_from_dict(h, O) def sdm_LM(f): r""" Returns the leading monomial of ``f``. Only valid if `f \ne 0`. Examples ======== >>> from sympy.polys.distributedmodules import sdm_LM, sdm_from_dict >>> from sympy.polys import QQ, lex >>> dic = {(1, 2, 3): QQ(1), (4, 0, 0): QQ(1), (4, 0, 1): QQ(1)} >>> sdm_LM(sdm_from_dict(dic, lex)) (4, 0, 1) """ return f[0][0] def sdm_LT(f): r""" Returns the leading term of ``f``. Only valid if `f \ne 0`. Examples ======== >>> from sympy.polys.distributedmodules import sdm_LT, sdm_from_dict >>> from sympy.polys import QQ, lex >>> dic = {(1, 2, 3): QQ(1), (4, 0, 0): QQ(2), (4, 0, 1): QQ(3)} >>> sdm_LT(sdm_from_dict(dic, lex)) ((4, 0, 1), 3) """ return f[0] def sdm_mul_term(f, term, O, K): """ Multiply a distributed module element ``f`` by a (polynomial) term ``term``. Multiplication of coefficients is done over the ground field ``K``, and monomials are ordered according to ``O``. Examples ======== `0 f_1 = 0` >>> from sympy.polys.distributedmodules import sdm_mul_term >>> from sympy.polys import lex, QQ >>> sdm_mul_term([((1, 0, 0), QQ(1))], ((0, 0), QQ(0)), lex, QQ) [] `x 0 = 0` >>> sdm_mul_term([], ((1, 0), QQ(1)), lex, QQ) [] `(x) (f_1) = xf_1` >>> sdm_mul_term([((1, 0, 0), QQ(1))], ((1, 0), QQ(1)), lex, QQ) [((1, 1, 0), 1)] `(2xy) (3x f_1 + 4y f_2) = 8xy^2 f_2 + 6x^2y f_1` >>> f = [((2, 0, 1), QQ(4)), ((1, 1, 0), QQ(3))] >>> sdm_mul_term(f, ((1, 1), QQ(2)), lex, QQ) [((2, 1, 2), 8), ((1, 2, 1), 6)] """ X, c = term if not f or not c: return [] else: if K.is_one(c): return [ (sdm_monomial_mul(f_M, X), f_c) for f_M, f_c in f ] else: return [ (sdm_monomial_mul(f_M, X), f_c * c) for f_M, f_c in f ] def sdm_zero(): """Return the zero module element.""" return [] def sdm_deg(f): """ Degree of ``f``. This is the maximum of the degrees of all its monomials. Invalid if ``f`` is zero. Examples ======== >>> from sympy.polys.distributedmodules import sdm_deg >>> sdm_deg([((1, 2, 3), 1), ((10, 0, 1), 1), ((2, 3, 4), 4)]) 7 """ return max(sdm_monomial_deg(M[0]) for M in f) # Conversion def sdm_from_vector(vec, O, K, opts): """ Create an sdm from an iterable of expressions. Coefficients are created in the ground field ``K``, and terms are ordered according to monomial order ``O``. Named arguments are passed on to the polys conversion code and can be used to specify for example generators. Examples ======== >>> from sympy.polys.distributedmodules import sdm_from_vector >>> from sympy.abc import x, y, z >>> from sympy.polys import QQ, lex >>> sdm_from_vector([x2+y*2, 2z], lex, QQ) [((1, 0, 0, 1), 2), ((0, 2, 0, 0), 1), ((0, 0, 2, 0), 1)] """ dics, gens = parallel_dict_from_expr(sympify(vec), opts) dic = {} for i, d in enumerate(dics): for k, v in d.items(): dic[(i,) + k] = K.convert(v) return sdm_from_dict(dic, O) def sdm_to_vector(f, gens, K, n=None): """ Convert sdm ``f`` into a list of polynomial expressions. The generators for the polynomial ring are specified via ``gens``. The rank of the module is guessed, or passed via ``n``. The ground field is assumed to be ``K``. Examples ======== >>> from sympy.polys.distributedmodules import sdm_to_vector >>> from sympy.abc import x, y, z >>> from sympy.polys import QQ, lex >>> f = [((1, 0, 0, 1), QQ(2)), ((0, 2, 0, 0), QQ(1)), ((0, 0, 2, 0), QQ(1))] >>> sdm_to_vector(f, [x, y, z], QQ) [x2 + y*2, 2z] """ dic = sdm_to_dict(f) dics = {} for k, v in dic.items(): dics.setdefault(k[0], []).append((k[1:], v)) n = n or len(dics) res = [] for k in range(n): if k in dics: res.append(Poly(dict(dics[k]), gens=gens, domain=K).as_expr()) else: res.append(S.Zero) return res # Algorithms. def sdm_spoly(f, g, O, K, phantom=None): """ Compute the generalized s-polynomial of ``f`` and ``g``. The ground field is assumed to be ``K``, and monomials ordered according to ``O``. This is invalid if either of ``f`` or ``g`` is zero. If the leading terms of `f` and `g` involve different basis elements of `F`, their s-poly is defined to be zero. Otherwise it is a certain linear combination of `f` and `g` in which the leading terms cancel. See [SCA, defn 2.3.6] for details. If ``phantom`` is not ``None``, it should be a pair of module elements on which to perform the same operation(s) as on ``f`` and ``g``. The in this case both results are returned. Examples ======== >>> from sympy.polys.distributedmodules import sdm_spoly >>> from sympy.polys import QQ, lex >>> f = [((2, 1, 1), QQ(1)), ((1, 0, 1), QQ(1))] >>> g = [((2, 3, 0), QQ(1))] >>> h = [((1, 2, 3), QQ(1))] >>> sdm_spoly(f, h, lex, QQ) [] >>> sdm_spoly(f, g, lex, QQ) [((1, 2, 1), 1)] """ if not f or not g: return sdm_zero() LM1 = sdm_LM(f) LM2 = sdm_LM(g) if LM1[0] != LM2[0]: return sdm_zero() LM1 = LM1[1:] LM2 = LM2[1:] lcm = monomial_lcm(LM1, LM2) m1 = monomial_div(lcm, LM1) m2 = monomial_div(lcm, LM2) c = K.quo(-sdm_LC(f, K), sdm_LC(g, K)) r1 = sdm_add(sdm_mul_term(f, (m1, K.one), O, K), sdm_mul_term(g, (m2, c), O, K), O, K) if phantom is None: return r1 r2 = sdm_add(sdm_mul_term(phantom[0], (m1, K.one), O, K), sdm_mul_term(phantom[1], (m2, c), O, K), O, K) return r1, r2 def sdm_ecart(f): """ Compute the ecart of ``f``. This is defined to be the difference of the total degree of `f` and the total degree of the leading monomial of `f` [SCA, defn 2.3.7]. Invalid if f is zero. Examples ======== >>> from sympy.polys.distributedmodules import sdm_ecart >>> sdm_ecart([((1, 2, 3), 1), ((1, 0, 1), 1)]) 0 >>> sdm_ecart([((2, 2, 1), 1), ((1, 5, 1), 1)]) 3 """ return sdm_deg(f) - sdm_monomial_deg(sdm_LM(f)) def sdm_nf_mora(f, G, O, K, phantom=None): r""" Compute a weak normal form of ``f`` with respect to ``G`` and order ``O``. The ground field is assumed to be ``K``, and monomials ordered according to ``O``. Weak normal forms are defined in [SCA, defn 2.3.3]. They are not unique. This function deterministically computes a weak normal form, depending on the order of `G`. The most important property of a weak normal form is the following: if `R` is the ring associated with the monomial ordering (if the ordering is global, we just have `R = K[x_1, \ldots, x_n]`, otherwise it is a certain localization thereof), `I` any ideal of `R` and `G` a standard basis for `I`, then for any `f \in R`, we have `f \in I` if and only if `NF(f \| G) = 0`. This is the generalized Mora algorithm for computing weak normal forms with respect to arbitrary monomial orders [SCA, algorithm 2.3.9]. If ``phantom`` is not ``None``, it should be a pair of "phantom" arguments on which to perform the same computations as on ``f``, ``G``, both results are then returned. """ from itertools import repeat h = f T = list(G) if phantom is not None: # "phantom" variables with suffix p hp = phantom[0] Tp = list(phantom[1]) phantom = True else: Tp = repeat([]) phantom = False while h: # TODO better data structure!!! Th = [(g, sdm_ecart(g), gp) for g, gp in zip(T, Tp) if sdm_monomial_divides(sdm_LM(g), sdm_LM(h))] if not Th: break g, _, gp = min(Th, key=lambda x: x[1]) if sdm_ecart(g) > sdm_ecart(h): T.append(h) if phantom: Tp.append(hp) if phantom: h, hp = sdm_spoly(h, g, O, K, phantom=(hp, gp)) else: h = sdm_spoly(h, g, O, K) if phantom: return h, hp return h def sdm_nf_buchberger(f, G, O, K, phantom=None): r""" Compute a weak normal form of ``f`` with respect to ``G`` and order ``O``. The ground field is assumed to be ``K``, and monomials ordered according to ``O``. This is the standard Buchberger algorithm for computing weak normal forms with respect to global monomial orders [SCA, algorithm 1.6.10]. If ``phantom`` is not ``None``, it should be a pair of "phantom" arguments on which to perform the same computations as on ``f``, ``G``, both results are then returned. """ from itertools import repeat h = f T = list(G) if phantom is not None: # "phantom" variables with suffix p hp = phantom[0] Tp = list(phantom[1]) phantom = True else: Tp = repeat([]) phantom = False while h: try: g, gp = next((g, gp) for g, gp in zip(T, Tp) if sdm_monomial_divides(sdm_LM(g), sdm_LM(h))) except StopIteration: break if phantom: h, hp = sdm_spoly(h, g, O, K, phantom=(hp, gp)) else: h = sdm_spoly(h, g, O, K) if phantom: return h, hp return h def sdm_nf_buchberger_reduced(f, G, O, K): r""" Compute a reduced normal form of ``f`` with respect to ``G`` and order ``O``. The ground field is assumed to be ``K``, and monomials ordered according to ``O``. In contrast to weak normal forms, reduced normal forms are unique, but their computation is more expensive. This is the standard Buchberger algorithm for computing reduced normal forms with respect to global monomial orders [SCA, algorithm 1.6.11]. The ``pantom`` option is not supported, so this normal form cannot be used as a normal form for the "extended" groebner algorithm. """ h = sdm_zero() g = f while g: g = sdm_nf_buchberger(g, G, O, K) if g: h = sdm_add(h, [sdm_LT(g)], O, K) g = g[1:] return h def sdm_groebner(G, NF, O, K, extended=False): """ Compute a minimal standard basis of ``G`` with respect to order ``O``. The algorithm uses a normal form ``NF``, for example ``sdm_nf_mora``. The ground field is assumed to be ``K``, and monomials ordered according to ``O``. Let `N` denote the submodule generated by elements of `G`. A standard basis for `N` is a subset `S` of `N`, such that `in(S) = in(N)`, where for any subset `X` of `F`, `in(X)` denotes the submodule generated by the initial forms of elements of `X`. [SCA, defn 2.3.2] A standard basis is called minimal if no subset of it is a standard basis. One may show that standard bases are always generating sets. Minimal standard bases are not unique. This algorithm computes a deterministic result, depending on the particular order of `G`. If ``extended=True``, also compute the transition matrix from the initial generators to the groebner basis. That is, return a list of coefficient vectors, expressing the elements of the groebner basis in terms of the elements of ``G``. This functions implements the "sugar" strategy, see Giovini et al: "One sugar cube, please" OR Selection strategies in Buchberger algorithm. """ # The critical pair set. # A critical pair is stored as (i, j, s, t) where (i, j) defines the pair # (by indexing S), s is the sugar of the pair, and t is the lcm of their # leading monomials. P = [] # The eventual standard basis. S = [] Sugars = [] def Ssugar(i, j): """Compute the sugar of the S-poly corresponding to (i, j).""" LMi = sdm_LM(S[i]) LMj = sdm_LM(S[j]) return max(Sugars[i] - sdm_monomial_deg(LMi), Sugars[j] - sdm_monomial_deg(LMj)) \ + sdm_monomial_deg(sdm_monomial_lcm(LMi, LMj)) ourkey = lambda p: (p[2], O(p[3]), p[1]) def update(f, sugar, P): """Add f with sugar ``sugar`` to S, update P.""" if not f: return P k = len(S) S.append(f) Sugars.append(sugar) LMf = sdm_LM(f) def removethis(pair): i, j, s, t = pair if LMf[0] != t[0]: return False tik = sdm_monomial_lcm(LMf, sdm_LM(S[i])) tjk = sdm_monomial_lcm(LMf, sdm_LM(S[j])) return tik != t and tjk != t and sdm_monomial_divides(tik, t) and \ sdm_monomial_divides(tjk, t) # apply the chain criterion P = [p for p in P if not removethis(p)] # new-pair set N = [(i, k, Ssugar(i, k), sdm_monomial_lcm(LMf, sdm_LM(S[i]))) for i in range(k) if LMf[0] == sdm_LM(S[i])[0]] # TODO apply the product criterion? N.sort(key=ourkey) remove = set() for i, p in enumerate(N): for j in range(i + 1, len(N)): if sdm_monomial_divides(p[3], N[j][3]): remove.add(j) # TODO mergesort? P.extend(reversed([p for i, p in enumerate(N) if not i in remove])) P.sort(key=ourkey, reverse=True) # NOTE reverse-sort, because we want to pop from the end return P # Figure out the number of generators in the ground ring. try: # NOTE: we look for the first non-zero vector, take its first monomial # the number of generators in the ring is one less than the length # (since the zeroth entry is for the module generators) numgens = len(next(x[0] for x in G if x)[0]) - 1 except StopIteration: # No non-zero elements in G ... if extended: return [], [] return [] # This list will store expressions of the elements of S in terms of the # initial generators coefficients = [] # First add all the elements of G to S for i, f in enumerate(G): P = update(f, sdm_deg(f), P) if extended and f: coefficients.append(sdm_from_dict({(i,) + (0,)*numgens: K(1)}, O)) # Now carry out the buchberger algorithm. while P: i, j, s, t = P.pop() f, g = S[i], S[j] if extended: sp, coeff = sdm_spoly(f, g, O, K, phantom=(coefficients[i], coefficients[j])) h, hcoeff = NF(sp, S, O, K, phantom=(coeff, coefficients)) if h: coefficients.append(hcoeff) else: h = NF(sdm_spoly(f, g, O, K), S, O, K) P = update(h, Ssugar(i, j), P) # Finally interreduce the standard basis. # (TODO again, better data structures) S = set((tuple(f), i) for i, f in enumerate(S)) for (a, ai), (b, bi) in permutations(S, 2): A = sdm_LM(a) B = sdm_LM(b) if sdm_monomial_divides(A, B) and (b, bi) in S and (a, ai) in S: S.remove((b, bi)) L = sorted(((list(f), i) for f, i in S), key=lambda p: O(sdm_LM(p[0])), reverse=True) res = [x[0] for x in L] if extended: return res, [coefficients[i] for _, i in L] return res
35054c0c09a2c51bcdd2b876f3ced05687ffeee97ec92c063482ce9e391b74f1	""" Generic Unification algorithm for expression trees with lists of children This implementation is a direct translation of Artificial Intelligence: A Modern Approach by Stuart Russel and Peter Norvig Second edition, section 9.2, page 276 It is modified in the following ways: 1. We allow associative and commutative Compound expressions. This results in combinatorial blowup. 2. We explore the tree lazily. 3. We provide generic interfaces to symbolic algebra libraries in Python. A more traditional version can be found here http://aima.cs.berkeley.edu/python/logic.html """ from __future__ import print_function, division from sympy.core.compatibility import range from sympy.utilities.iterables import kbins class Compound(object): """ A little class to represent an interior node in the tree This is analogous to SymPy.Basic for non-Atoms """ def __init__(self, op, args): self.op = op self.args = args def __eq__(self, other): return (type(self) == type(other) and self.op == other.op and self.args == other.args) def __hash__(self): return hash((type(self), self.op, self.args)) def __str__(self): return "%s[%s]" % (str(self.op), ', '.join(map(str, self.args))) class Variable(object): """ A Wild token """ def __init__(self, arg): self.arg = arg def __eq__(self, other): return type(self) == type(other) and self.arg == other.arg def __hash__(self): return hash((type(self), self.arg)) def __str__(self): return "Variable(%s)" % str(self.arg) class CondVariable(object): """ A wild token that matches conditionally arg - a wild token valid - an additional constraining function on a match """ def __init__(self, arg, valid): self.arg = arg self.valid = valid def __eq__(self, other): return (type(self) == type(other) and self.arg == other.arg and self.valid == other.valid) def __hash__(self): return hash((type(self), self.arg, self.valid)) def __str__(self): return "CondVariable(%s)" % str(self.arg) def unify(x, y, s=None, fns): """ Unify two expressions Parameters ========== x, y - expression trees containing leaves, Compounds and Variables s - a mapping of variables to subtrees Returns ======= lazy sequence of mappings {Variable: subtree} Examples ======== >>> from sympy.unify.core import unify, Compound, Variable >>> expr = Compound("Add", ("x", "y")) >>> pattern = Compound("Add", ("x", Variable("a"))) >>> next(unify(expr, pattern, {})) {Variable(a): 'y'} """ s = s or {} if x == y: yield s elif isinstance(x, (Variable, CondVariable)): for match in unify_var(x, y, s, fns): yield match elif isinstance(y, (Variable, CondVariable)): for match in unify_var(y, x, s, fns): yield match elif isinstance(x, Compound) and isinstance(y, Compound): is_commutative = fns.get('is_commutative', lambda x: False) is_associative = fns.get('is_associative', lambda x: False) for sop in unify(x.op, y.op, s, fns): if is_associative(x) and is_associative(y): a, b = (x, y) if len(x.args) < len(y.args) else (y, x) if is_commutative(x) and is_commutative(y): combs = allcombinations(a.args, b.args, 'commutative') else: combs = allcombinations(a.args, b.args, 'associative') for aaargs, bbargs in combs: aa = [unpack(Compound(a.op, arg)) for arg in aaargs] bb = [unpack(Compound(b.op, arg)) for arg in bbargs] for match in unify(aa, bb, sop, fns): yield match elif len(x.args) == len(y.args): for match in unify(x.args, y.args, sop, fns): yield match elif is_args(x) and is_args(y) and len(x) == len(y): if len(x) == 0: yield s else: for shead in unify(x[0], y[0], s, fns): for match in unify(x[1:], y[1:], shead, fns): yield match def unify_var(var, x, s, fns): if var in s: for match in unify(s[var], x, s, fns): yield match elif occur_check(var, x): pass elif isinstance(var, CondVariable) and var.valid(x): yield assoc(s, var, x) elif isinstance(var, Variable): yield assoc(s, var, x) def occur_check(var, x): """ var occurs in subtree owned by x? """ if var == x: return True elif isinstance(x, Compound): return occur_check(var, x.args) elif is_args(x): if any(occur_check(var, xi) for xi in x): return True return False def assoc(d, key, val): """ Return copy of d with key associated to val """ d = d.copy() d[key] = val return d def is_args(x): """ Is x a traditional iterable? """ return type(x) in (tuple, list, set) def unpack(x): if isinstance(x, Compound) and len(x.args) == 1: return x.args[0] else: return x def allcombinations(A, B, ordered): """ Restructure A and B to have the same number of elements ordered must be either 'commutative' or 'associative' A and B can be rearranged so that the larger of the two lists is reorganized into smaller sublists. Examples ======== >>> from sympy.unify.core import allcombinations >>> for x in allcombinations((1, 2, 3), (5, 6), 'associative'): print(x) (((1,), (2, 3)), ((5,), (6,))) (((1, 2), (3,)), ((5,), (6,))) >>> for x in allcombinations((1, 2, 3), (5, 6), 'commutative'): print(x) (((1,), (2, 3)), ((5,), (6,))) (((1, 2), (3,)), ((5,), (6,))) (((1,), (3, 2)), ((5,), (6,))) (((1, 3), (2,)), ((5,), (6,))) (((2,), (1, 3)), ((5,), (6,))) (((2, 1), (3,)), ((5,), (6,))) (((2,), (3, 1)), ((5,), (6,))) (((2, 3), (1,)), ((5,), (6,))) (((3,), (1, 2)), ((5,), (6,))) (((3, 1), (2,)), ((5,), (6,))) (((3,), (2, 1)), ((5,), (6,))) (((3, 2), (1,)), ((5,), (6,))) """ if ordered == "commutative": ordered = 11 if ordered == "associative": ordered = None sm, bg = (A, B) if len(A) < len(B) else (B, A) for part in kbins(list(range(len(bg))), len(sm), ordered=ordered): if bg == B: yield tuple((a,) for a in A), partition(B, part) else: yield partition(A, part), tuple((b,) for b in B) def partition(it, part): """ Partition a tuple/list into pieces defined by indices Examples ======== >>> from sympy.unify.core import partition >>> partition((10, 20, 30, 40), [[0, 1, 2], [3]]) ((10, 20, 30), (40,)) """ return type(it)([index(it, ind) for ind in part]) def index(it, ind): """ Fancy indexing into an indexable iterable (tuple, list) Examples ======== >>> from sympy.unify.core import index >>> index([10, 20, 30], (1, 2, 0)) [20, 30, 10] """ return type(it)([it[i] for i in ind])
7630370764b0a391a02f5671f13c00f053246117dcddc0402df3c8c420adf511	""" SymPy interface to Unification engine See sympy.unify for module level docstring See sympy.unify.core for algorithmic docstring """ from __future__ import print_function, division from sympy.core import Basic, Add, Mul, Pow from sympy.core.operations import AssocOp, LatticeOp from sympy.matrices import MatAdd, MatMul, MatrixExpr from sympy.sets.sets import Union, Intersection, FiniteSet from sympy.unify.core import Compound, Variable, CondVariable from sympy.unify import core basic_new_legal = [MatrixExpr] eval_false_legal = [AssocOp, Pow, FiniteSet] illegal = [LatticeOp] def sympy_associative(op): assoc_ops = (AssocOp, MatAdd, MatMul, Union, Intersection, FiniteSet) return any(issubclass(op, aop) for aop in assoc_ops) def sympy_commutative(op): comm_ops = (Add, MatAdd, Union, Intersection, FiniteSet) return any(issubclass(op, cop) for cop in comm_ops) def is_associative(x): return isinstance(x, Compound) and sympy_associative(x.op) def is_commutative(x): if not isinstance(x, Compound): return False if sympy_commutative(x.op): return True if issubclass(x.op, Mul): return all(construct(arg).is_commutative for arg in x.args) def mk_matchtype(typ): def matchtype(x): return (isinstance(x, typ) or isinstance(x, Compound) and issubclass(x.op, typ)) return matchtype def deconstruct(s, variables=()): """ Turn a SymPy object into a Compound """ if s in variables: return Variable(s) if isinstance(s, (Variable, CondVariable)): return s if not isinstance(s, Basic) or s.is_Atom: return s return Compound(s.__class__, tuple(deconstruct(arg, variables) for arg in s.args)) def construct(t): """ Turn a Compound into a SymPy object """ if isinstance(t, (Variable, CondVariable)): return t.arg if not isinstance(t, Compound): return t if any(issubclass(t.op, cls) for cls in eval_false_legal): return t.op(map(construct, t.args), evaluate=False) elif any(issubclass(t.op, cls) for cls in basic_new_legal): return Basic.__new__(t.op, map(construct, t.args)) else: return t.op(map(construct, t.args)) def rebuild(s): """ Rebuild a SymPy expression This removes harm caused by Expr-Rules interactions """ return construct(deconstruct(s)) def unify(x, y, s=None, variables=(), kwargs): """ Structural unification of two expressions/patterns Examples ======== >>> from sympy.unify.usympy import unify >>> from sympy import Basic, cos >>> from sympy.abc import x, y, z, p, q >>> next(unify(Basic(1, 2), Basic(1, x), variables=[x])) {x: 2} >>> expr = 2x + y + z >>> pattern = 2p + q >>> next(unify(expr, pattern, {}, variables=(p, q))) {p: x, q: y + z} Unification supports commutative and associative matching >>> expr = x + y + z >>> pattern = p + q >>> len(list(unify(expr, pattern, {}, variables=(p, q)))) 12 Symbols not indicated to be variables are treated as literal, else they are wild-like and match anything in a sub-expression. >>> expr = xyz + 3 >>> pattern = xy + 3 >>> next(unify(expr, pattern, {}, variables=[x, y])) {x: y, y: xz} The x and y of the pattern above were in a Mul and matched factors in the Mul of expr. Here, a single symbol matches an entire term: >>> expr = xy + 3 >>> pattern = p + 3 >>> next(unify(expr, pattern, {}, variables=[p])) {p: xy} """ decons = lambda x: deconstruct(x, variables) s = s or {} s = dict((decons(k), decons(v)) for k, v in s.items()) ds = core.unify(decons(x), decons(y), s, is_associative=is_associative, is_commutative=is_commutative, *kwargs) for d in ds: yield dict((construct(k), construct(v)) for k, v in d.items())

09179d43ff9d1b2d7b5a0ff238746170ca0cf3a754f864f1c7e2a60e058ff4d9

from sympy import Abs, Rational, Float, S, Symbol, symbols, cos, pi, sqrt, oo from sympy.functions.elementary.trigonometric import tan from sympy.geometry import (Circle, Ellipse, GeometryError, Point, Point2D, Polygon, Ray, RegularPolygon, Segment, Triangle, are_similar, convex_hull, intersection, Line) from sympy.utilities.pytest import raises, slow, warns from sympy.utilities.randtest import verify_numerically from sympy.geometry.polygon import rad, deg from sympy import integrate def feq(a, b): """Test if two floating point values are 'equal'.""" t_float = Float("1.0E-10") return -t_float < a - b < t_float @slow def test_polygon(): x = Symbol('x', real=True) y = Symbol('y', real=True) q = Symbol('q', real=True) u = Symbol('u', real=True) v = Symbol('v', real=True) w = Symbol('w', real=True) x1 = Symbol('x1', real=True) half = Rational(1, 2) a, b, c = Point(0, 0), Point(2, 0), Point(3, 3) t = Triangle(a, b, c) assert Polygon(a, Point(1, 0), b, c) == t assert Polygon(Point(1, 0), b, c, a) == t assert Polygon(b, c, a, Point(1, 0)) == t # 2 "remove folded" tests assert Polygon(a, Point(3, 0), b, c) == t assert Polygon(a, b, Point(3, -1), b, c) == t # remove multiple collinear points assert Polygon(Point(-4, 15), Point(-11, 15), Point(-15, 15), Point(-15, 33/5), Point(-15, -87/10), Point(-15, -15), Point(-42/5, -15), Point(-2, -15), Point(7, -15), Point(15, -15), Point(15, -3), Point(15, 10), Point(15, 15)) == \ Polygon(Point(-15,-15), Point(15,-15), Point(15,15), Point(-15,15)) p1 = Polygon( Point(0, 0), Point(3, -1), Point(6, 0), Point(4, 5), Point(2, 3), Point(0, 3)) p2 = Polygon( Point(6, 0), Point(3, -1), Point(0, 0), Point(0, 3), Point(2, 3), Point(4, 5)) p3 = Polygon( Point(0, 0), Point(3, 0), Point(5, 2), Point(4, 4)) p4 = Polygon( Point(0, 0), Point(4, 4), Point(5, 2), Point(3, 0)) p5 = Polygon( Point(0, 0), Point(4, 4), Point(0, 4)) p6 = Polygon( Point(-11, 1), Point(-9, 6.6), Point(-4, -3), Point(-8.4, -8.7)) p7 = Polygon( Point(x, y), Point(q, u), Point(v, w)) p8 = Polygon( Point(x, y), Point(v, w), Point(q, u)) p9 = Polygon( Point(0, 0), Point(4, 4), Point(3, 0), Point(5, 2)) r = Ray(Point(-9,6.6), Point(-9,5.5)) # # General polygon # assert p1 == p2 assert len(p1.args) == 6 assert len(p1.sides) == 6 assert p1.perimeter == 5 + 2*sqrt(10) + sqrt(29) + sqrt(8) assert p1.area == 22 assert not p1.is_convex() assert Polygon((-1, 1), (2, -1), (2, 1), (-1, -1), (3, 0) ).is_convex() is False # ensure convex for both CW and CCW point specification assert p3.is_convex() assert p4.is_convex() dict5 = p5.angles assert dict5[Point(0, 0)] == pi / 4 assert dict5[Point(0, 4)] == pi / 2 assert p5.encloses_point(Point(x, y)) is None assert p5.encloses_point(Point(1, 3)) assert p5.encloses_point(Point(0, 0)) is False assert p5.encloses_point(Point(4, 0)) is False assert p1.encloses(Circle(Point(2.5,2.5),5)) is False assert p1.encloses(Ellipse(Point(2.5,2),5,6)) is False p5.plot_interval('x') == [x, 0, 1] assert p5.distance( Polygon(Point(10, 10), Point(14, 14), Point(10, 14))) == 6 * sqrt(2) assert p5.distance( Polygon(Point(1, 8), Point(5, 8), Point(8, 12), Point(1, 12))) == 4 with warns(UserWarning, match="Polygons may intersect producing erroneous output"): Polygon(Point(0, 0), Point(1, 0), Point(1, 1)).distance( Polygon(Point(0, 0), Point(0, 1), Point(1, 1))) assert hash(p5) == hash(Polygon(Point(0, 0), Point(4, 4), Point(0, 4))) assert hash(p1) == hash(p2) assert hash(p7) == hash(p8) assert hash(p3) != hash(p9) assert p5 == Polygon(Point(4, 4), Point(0, 4), Point(0, 0)) assert Polygon(Point(4, 4), Point(0, 4), Point(0, 0)) in p5 assert p5 != Point(0, 4) assert Point(0, 1) in p5 assert p5.arbitrary_point('t').subs(Symbol('t', real=True), 0) == \ Point(0, 0) raises(ValueError, lambda: Polygon( Point(x, 0), Point(0, y), Point(x, y)).arbitrary_point('x')) assert p6.intersection(r) == [Point(-9, -84/13), Point(-9, 33/5)] # # Regular polygon # p1 = RegularPolygon(Point(0, 0), 10, 5) p2 = RegularPolygon(Point(0, 0), 5, 5) raises(GeometryError, lambda: RegularPolygon(Point(0, 0), Point(0, 1), Point(1, 1))) raises(GeometryError, lambda: RegularPolygon(Point(0, 0), 1, 2)) raises(ValueError, lambda: RegularPolygon(Point(0, 0), 1, 2.5)) assert p1 != p2 assert p1.interior_angle == 3*pi/5 assert p1.exterior_angle == 2*pi/5 assert p2.apothem == 5*cos(pi/5) assert p2.circumcenter == p1.circumcenter == Point(0, 0) assert p1.circumradius == p1.radius == 10 assert p2.circumcircle == Circle(Point(0, 0), 5) assert p2.incircle == Circle(Point(0, 0), p2.apothem) assert p2.inradius == p2.apothem == (5 * (1 + sqrt(5)) / 4) p2.spin(pi / 10) dict1 = p2.angles assert dict1[Point(0, 5)] == 3 * pi / 5 assert p1.is_convex() assert p1.rotation == 0 assert p1.encloses_point(Point(0, 0)) assert p1.encloses_point(Point(11, 0)) is False assert p2.encloses_point(Point(0, 4.9)) p1.spin(pi/3) assert p1.rotation == pi/3 assert p1.vertices[0] == Point(5, 5*sqrt(3)) for var in p1.args: if isinstance(var, Point): assert var == Point(0, 0) else: assert var == 5 or var == 10 or var == pi / 3 assert p1 != Point(0, 0) assert p1 != p5 # while spin works in place (notice that rotation is 2pi/3 below) # rotate returns a new object p1_old = p1 assert p1.rotate(pi/3) == RegularPolygon(Point(0, 0), 10, 5, 2*pi/3) assert p1 == p1_old assert p1.area == (-250*sqrt(5) + 1250)/(4*tan(pi/5)) assert p1.length == 20*sqrt(-sqrt(5)/8 + 5/8) assert p1.scale(2, 2) == \ RegularPolygon(p1.center, p1.radius*2, p1._n, p1.rotation) assert RegularPolygon((0, 0), 1, 4).scale(2, 3) == \ Polygon(Point(2, 0), Point(0, 3), Point(-2, 0), Point(0, -3)) assert repr(p1) == str(p1) # # Angles # angles = p4.angles assert feq(angles[Point(0, 0)].evalf(), Float("0.7853981633974483")) assert feq(angles[Point(4, 4)].evalf(), Float("1.2490457723982544")) assert feq(angles[Point(5, 2)].evalf(), Float("1.8925468811915388")) assert feq(angles[Point(3, 0)].evalf(), Float("2.3561944901923449")) angles = p3.angles assert feq(angles[Point(0, 0)].evalf(), Float("0.7853981633974483")) assert feq(angles[Point(4, 4)].evalf(), Float("1.2490457723982544")) assert feq(angles[Point(5, 2)].evalf(), Float("1.8925468811915388")) assert feq(angles[Point(3, 0)].evalf(), Float("2.3561944901923449")) # # Triangle # p1 = Point(0, 0) p2 = Point(5, 0) p3 = Point(0, 5) t1 = Triangle(p1, p2, p3) t2 = Triangle(p1, p2, Point(Rational(5, 2), sqrt(Rational(75, 4)))) t3 = Triangle(p1, Point(x1, 0), Point(0, x1)) s1 = t1.sides assert Triangle(p1, p2, p1) == Polygon(p1, p2, p1) == Segment(p1, p2) raises(GeometryError, lambda: Triangle(Point(0, 0))) # Basic stuff assert Triangle(p1, p1, p1) == p1 assert Triangle(p2, p2*2, p2*3) == Segment(p2, p2*3) assert t1.area == Rational(25, 2) assert t1.is_right() assert t2.is_right() is False assert t3.is_right() assert p1 in t1 assert t1.sides[0] in t1 assert Segment((0, 0), (1, 0)) in t1 assert Point(5, 5) not in t2 assert t1.is_convex() assert feq(t1.angles[p1].evalf(), pi.evalf()/2) assert t1.is_equilateral() is False assert t2.is_equilateral() assert t3.is_equilateral() is False assert are_similar(t1, t2) is False assert are_similar(t1, t3) assert are_similar(t2, t3) is False assert t1.is_similar(Point(0, 0)) is False # Bisectors bisectors = t1.bisectors() assert bisectors[p1] == Segment(p1, Point(Rational(5, 2), Rational(5, 2))) ic = (250 - 125*sqrt(2)) / 50 assert t1.incenter == Point(ic, ic) # Inradius assert t1.inradius == t1.incircle.radius == 5 - 5*sqrt(2)/2 assert t2.inradius == t2.incircle.radius == 5*sqrt(3)/6 assert t3.inradius == t3.incircle.radius == x1**2/((2 + sqrt(2))*Abs(x1)) # Exradius assert t1.exradii[t1.sides[2]] == 5*sqrt(2)/2 # Circumcircle assert t1.circumcircle.center == Point(2.5, 2.5) # Medians + Centroid m = t1.medians assert t1.centroid == Point(Rational(5, 3), Rational(5, 3)) assert m[p1] == Segment(p1, Point(Rational(5, 2), Rational(5, 2))) assert t3.medians[p1] == Segment(p1, Point(x1/2, x1/2)) assert intersection(m[p1], m[p2], m[p3]) == [t1.centroid] assert t1.medial == Triangle(Point(2.5, 0), Point(0, 2.5), Point(2.5, 2.5)) # Nine-point circle assert t1.nine_point_circle == Circle(Point(2.5, 0), Point(0, 2.5), Point(2.5, 2.5)) assert t1.nine_point_circle == Circle(Point(0, 0), Point(0, 2.5), Point(2.5, 2.5)) # Perpendicular altitudes = t1.altitudes assert altitudes[p1] == Segment(p1, Point(Rational(5, 2), Rational(5, 2))) assert altitudes[p2].equals(s1[0]) assert altitudes[p3] == s1[2] assert t1.orthocenter == p1 t = S('''Triangle( Point(100080156402737/5000000000000, 79782624633431/500000000000), Point(39223884078253/2000000000000, 156345163124289/1000000000000), Point(31241359188437/1250000000000, 338338270939941/1000000000000000))''') assert t.orthocenter == S('''Point(-780660869050599840216997''' '''79471538701955848721853/80368430960602242240789074233100000000000000,''' '''20151573611150265741278060334545897615974257/16073686192120448448157''' '''8148466200000000000)''') # Ensure assert len(intersection(*bisectors.values())) == 1 assert len(intersection(*altitudes.values())) == 1 assert len(intersection(*m.values())) == 1 # Distance p1 = Polygon( Point(0, 0), Point(1, 0), Point(1, 1), Point(0, 1)) p2 = Polygon( Point(0, Rational(5)/4), Point(1, Rational(5)/4), Point(1, Rational(9)/4), Point(0, Rational(9)/4)) p3 = Polygon( Point(1, 2), Point(2, 2), Point(2, 1)) p4 = Polygon( Point(1, 1), Point(Rational(6)/5, 1), Point(1, Rational(6)/5)) pt1 = Point(half, half) pt2 = Point(1, 1) '''Polygon to Point''' assert p1.distance(pt1) == half assert p1.distance(pt2) == 0 assert p2.distance(pt1) == Rational(3)/4 assert p3.distance(pt2) == sqrt(2)/2 '''Polygon to Polygon''' # p1.distance(p2) emits a warning with warns(UserWarning, match="Polygons may intersect producing erroneous output"): assert p1.distance(p2) == half/2 assert p1.distance(p3) == sqrt(2)/2 # p3.distance(p4) emits a warning with warns(UserWarning, match="Polygons may intersect producing erroneous output"): assert p3.distance(p4) == (sqrt(2)/2 - sqrt(Rational(2)/25)/2) def test_convex_hull(): p = [Point(-5, -1), Point(-2, 1), Point(-2, -1), Point(-1, -3), Point(0, 0), Point(1, 1), Point(2, 2), Point(2, -1), Point(3, 1), Point(4, -1), Point(6, 2)] ch = Polygon(p[0], p[3], p[9], p[10], p[6], p[1]) #test handling of duplicate points p.append(p[3]) #more than 3 collinear points another_p = [Point(-45, -85), Point(-45, 85), Point(-45, 26), Point(-45, -24)] ch2 = Segment(another_p[0], another_p[1]) assert convex_hull(*another_p) == ch2 assert convex_hull(*p) == ch assert convex_hull(p[0]) == p[0] assert convex_hull(p[0], p[1]) == Segment(p[0], p[1]) # no unique points assert convex_hull(*[p[-1]]*3) == p[-1] # collection of items assert convex_hull(*[Point(0, 0), Segment(Point(1, 0), Point(1, 1)), RegularPolygon(Point(2, 0), 2, 4)]) == \ Polygon(Point(0, 0), Point(2, -2), Point(4, 0), Point(2, 2)) def test_encloses(): # square with a dimpled left side s = Polygon(Point(0, 0), Point(1, 0), Point(1, 1), Point(0, 1), Point(S.Half, S.Half)) # the following is True if the polygon isn't treated as closing on itself assert s.encloses(Point(0, S.Half)) is False assert s.encloses(Point(S.Half, S.Half)) is False # it's a vertex assert s.encloses(Point(Rational(3, 4), S.Half)) is True def test_triangle_kwargs(): assert Triangle(sss=(3, 4, 5)) == \ Triangle(Point(0, 0), Point(3, 0), Point(3, 4)) assert Triangle(asa=(30, 2, 30)) == \ Triangle(Point(0, 0), Point(2, 0), Point(1, sqrt(3)/3)) assert Triangle(sas=(1, 45, 2)) == \ Triangle(Point(0, 0), Point(2, 0), Point(sqrt(2)/2, sqrt(2)/2)) assert Triangle(sss=(1, 2, 5)) is None assert deg(rad(180)) == 180 def test_transform(): pts = [Point(0, 0), Point(S(1)/2, S(1)/4), Point(1, 1)] pts_out = [Point(-4, -10), Point(-3, -S(37)/4), Point(-2, -7)] assert Triangle(*pts).scale(2, 3, (4, 5)) == Triangle(*pts_out) assert RegularPolygon((0, 0), 1, 4).scale(2, 3, (4, 5)) == \ Polygon(Point(-2, -10), Point(-4, -7), Point(-6, -10), Point(-4, -13)) def test_reflect(): x = Symbol('x', real=True) y = Symbol('y', real=True) b = Symbol('b') m = Symbol('m') l = Line((0, b), slope=m) p = Point(x, y) r = p.reflect(l) dp = l.perpendicular_segment(p).length dr = l.perpendicular_segment(r).length assert verify_numerically(dp, dr) t = Triangle((0, 0), (1, 0), (2, 3)) assert Polygon((1, 0), (2, 0), (2, 2)).reflect(Line((3, 0), slope=oo)) \ == Triangle(Point(5, 0), Point(4, 0), Point(4, 2)) assert Polygon((1, 0), (2, 0), (2, 2)).reflect(Line((0, 3), slope=oo)) \ == Triangle(Point(-1, 0), Point(-2, 0), Point(-2, 2)) assert Polygon((1, 0), (2, 0), (2, 2)).reflect(Line((0, 3), slope=0)) \ == Triangle(Point(1, 6), Point(2, 6), Point(2, 4)) assert Polygon((1, 0), (2, 0), (2, 2)).reflect(Line((3, 0), slope=0)) \ == Triangle(Point(1, 0), Point(2, 0), Point(2, -2)) def test_eulerline(): assert Triangle(Point(0, 0), Point(1, 0), Point(0, 1)).eulerline \ == Line(Point2D(0, 0), Point2D(S(1)/2, S(1)/2)) assert Triangle(Point(0, 0), Point(10, 0), Point(5, 5*sqrt(3))).eulerline \ == Point2D(5, 5*sqrt(3)/3) assert Triangle(Point(4, -6), Point(4, -1), Point(-3, 3)).eulerline \ == Line(Point2D(S(64)/7, 3), Point2D(-S(29)/14, -S(7)/2)) def test_intersection(): poly1 = Triangle(Point(0, 0), Point(1, 0), Point(0, 1)) poly2 = Polygon(Point(0, 1), Point(-5, 0), Point(0, -4), Point(0, S(1)/5), Point(S(1)/2, -0.1), Point(1,0), Point(0, 1)) assert poly1.intersection(poly2) == [Point2D(S(1)/3, 0), Segment(Point(0, S(1)/5), Point(0, 0)), Segment(Point(1, 0), Point(0, 1))] assert poly2.intersection(poly1) == [Point(S(1)/3, 0), Segment(Point(0, 0), Point(0, S(1)/5)), Segment(Point(1, 0), Point(0, 1))] assert poly1.intersection(Point(0, 0)) == [Point(0, 0)] assert poly1.intersection(Point(-12, -43)) == [] assert poly2.intersection(Line((-12, 0), (12, 0))) == [Point(-5, 0), Point(0, 0), Point(S(1)/3, 0), Point(1, 0)] assert poly2.intersection(Line((-12, 12), (12, 12))) == [] assert poly2.intersection(Ray((-3,4), (1,0))) == [Segment(Point(1, 0), Point(0, 1))] assert poly2.intersection(Circle((0, -1), 1)) == [Point(0, -2), Point(0, 0)] assert poly1.intersection(poly1) == [Segment(Point(0, 0), Point(1, 0)), Segment(Point(0, 1), Point(0, 0)), Segment(Point(1, 0), Point(0, 1))] assert poly2.intersection(poly2) == [Segment(Point(-5, 0), Point(0, -4)), Segment(Point(0, -4), Point(0, S(1)/5)), Segment(Point(0, S(1)/5), Point(S(1)/2, -S(1)/10)), Segment(Point(0, 1), Point(-5, 0)), Segment(Point(S(1)/2, -S(1)/10), Point(1, 0)), Segment(Point(1, 0), Point(0, 1))] assert poly2.intersection(Triangle(Point(0, 1), Point(1, 0), Point(-1, 1))) == [Point(-S(5)/7, S(6)/7), Segment(Point2D(0, 1), Point(1, 0))] assert poly1.intersection(RegularPolygon((-12, -15), 3, 3)) == [] def test_parameter_value(): t = Symbol('t') sq = Polygon((0, 0), (0, 1), (1, 1), (1, 0)) assert sq.parameter_value((0.5, 1), t) == {t: S(3)/8} q = Polygon((0, 0), (2, 1), (2, 4), (4, 0)) assert q.parameter_value((4, 0), t) == {t: -6 + 3*sqrt(5)} # ~= 0.708 raises(ValueError, lambda: sq.parameter_value((5, 6), t)) def test_issue_12966(): poly = Polygon(Point(0, 0), Point(0, 10), Point(5, 10), Point(5, 5), Point(10, 5), Point(10, 0)) t = Symbol('t') pt = poly.arbitrary_point(t) DELTA = 5/poly.perimeter assert [pt.subs(t, DELTA*i) for i in range(int(1/DELTA))] == [ Point(0, 0), Point(0, 5), Point(0, 10), Point(5, 10), Point(5, 5), Point(10, 5), Point(10, 0), Point(5, 0)] def test_second_moment_of_area(): x, y = symbols('x, y') # triangle p1, p2, p3 = [(0, 0), (4, 0), (0, 2)] p = (0, 0) # equation of hypotenuse eq_y = (1-x/4)*2 I_yy = integrate((x**2) * (integrate(1, (y, 0, eq_y))), (x, 0, 4)) I_xx = integrate(1 * (integrate(y**2, (y, 0, eq_y))), (x, 0, 4)) I_xy = integrate(x * (integrate(y, (y, 0, eq_y))), (x, 0, 4)) triangle = Polygon(p1, p2, p3) assert (I_xx - triangle.second_moment_of_area(p)[0]) == 0 assert (I_yy - triangle.second_moment_of_area(p)[1]) == 0 assert (I_xy - triangle.second_moment_of_area(p)[2]) == 0 # rectangle p1, p2, p3, p4=[(0, 0), (4, 0), (4, 2), (0, 2)] I_yy = integrate((x**2) * integrate(1, (y, 0, 2)), (x, 0, 4)) I_xx = integrate(1 * integrate(y**2, (y, 0, 2)), (x, 0, 4)) I_xy = integrate(x * integrate(y, (y, 0, 2)), (x, 0, 4)) rectangle = Polygon(p1, p2, p3, p4) assert (I_xx - rectangle.second_moment_of_area(p)[0]) == 0 assert (I_yy - rectangle.second_moment_of_area(p)[1]) == 0 assert (I_xy - rectangle.second_moment_of_area(p)[2]) == 0

872bc993f155232066970cdf5a1ef7ec56ec4429061cb9559a8331583a6b2a6f

"""Utilities to deal with sympy.Matrix, numpy and scipy.sparse.""" from __future__ import print_function, division from sympy import MatrixBase, I, Expr, Integer from sympy.core.compatibility import range from sympy.matrices import eye, zeros from sympy.external import import_module __all__ = [ 'numpy_ndarray', 'scipy_sparse_matrix', 'sympy_to_numpy', 'sympy_to_scipy_sparse', 'numpy_to_sympy', 'scipy_sparse_to_sympy', 'flatten_scalar', 'matrix_dagger', 'to_sympy', 'to_numpy', 'to_scipy_sparse', 'matrix_tensor_product', 'matrix_zeros' ] # Conditionally define the base classes for numpy and scipy.sparse arrays # for use in isinstance tests. np = import_module('numpy') if not np: class numpy_ndarray(object): pass else: numpy_ndarray = np.ndarray scipy = import_module('scipy', __import__kwargs={'fromlist': ['sparse']}) if not scipy: class scipy_sparse_matrix(object): pass sparse = None else: sparse = scipy.sparse # Try to find spmatrix. if hasattr(sparse, 'base'): # Newer versions have it under scipy.sparse.base. scipy_sparse_matrix = sparse.base.spmatrix elif hasattr(sparse, 'sparse'): # Older versions have it under scipy.sparse.sparse. scipy_sparse_matrix = sparse.sparse.spmatrix def sympy_to_numpy(m, **options): """Convert a sympy Matrix/complex number to a numpy matrix or scalar.""" if not np: raise ImportError dtype = options.get('dtype', 'complex') if isinstance(m, MatrixBase): return np.matrix(m.tolist(), dtype=dtype) elif isinstance(m, Expr): if m.is_Number or m.is_NumberSymbol or m == I: return complex(m) raise TypeError('Expected MatrixBase or complex scalar, got: %r' % m) def sympy_to_scipy_sparse(m, **options): """Convert a sympy Matrix/complex number to a numpy matrix or scalar.""" if not np or not sparse: raise ImportError dtype = options.get('dtype', 'complex') if isinstance(m, MatrixBase): return sparse.csr_matrix(np.matrix(m.tolist(), dtype=dtype)) elif isinstance(m, Expr): if m.is_Number or m.is_NumberSymbol or m == I: return complex(m) raise TypeError('Expected MatrixBase or complex scalar, got: %r' % m) def scipy_sparse_to_sympy(m, **options): """Convert a scipy.sparse matrix to a sympy matrix.""" return MatrixBase(m.todense()) def numpy_to_sympy(m, **options): """Convert a numpy matrix to a sympy matrix.""" return MatrixBase(m) def to_sympy(m, **options): """Convert a numpy/scipy.sparse matrix to a sympy matrix.""" if isinstance(m, MatrixBase): return m elif isinstance(m, numpy_ndarray): return numpy_to_sympy(m) elif isinstance(m, scipy_sparse_matrix): return scipy_sparse_to_sympy(m) elif isinstance(m, Expr): return m raise TypeError('Expected sympy/numpy/scipy.sparse matrix, got: %r' % m) def to_numpy(m, **options): """Convert a sympy/scipy.sparse matrix to a numpy matrix.""" dtype = options.get('dtype', 'complex') if isinstance(m, (MatrixBase, Expr)): return sympy_to_numpy(m, dtype=dtype) elif isinstance(m, numpy_ndarray): return m elif isinstance(m, scipy_sparse_matrix): return m.todense() raise TypeError('Expected sympy/numpy/scipy.sparse matrix, got: %r' % m) def to_scipy_sparse(m, **options): """Convert a sympy/numpy matrix to a scipy.sparse matrix.""" dtype = options.get('dtype', 'complex') if isinstance(m, (MatrixBase, Expr)): return sympy_to_scipy_sparse(m, dtype=dtype) elif isinstance(m, numpy_ndarray): if not sparse: raise ImportError return sparse.csr_matrix(m) elif isinstance(m, scipy_sparse_matrix): return m raise TypeError('Expected sympy/numpy/scipy.sparse matrix, got: %r' % m) def flatten_scalar(e): """Flatten a 1x1 matrix to a scalar, return larger matrices unchanged.""" if isinstance(e, MatrixBase): if e.shape == (1, 1): e = e[0] if isinstance(e, (numpy_ndarray, scipy_sparse_matrix)): if e.shape == (1, 1): e = complex(e[0, 0]) return e def matrix_dagger(e): """Return the dagger of a sympy/numpy/scipy.sparse matrix.""" if isinstance(e, MatrixBase): return e.H elif isinstance(e, (numpy_ndarray, scipy_sparse_matrix)): return e.conjugate().transpose() raise TypeError('Expected sympy/numpy/scipy.sparse matrix, got: %r' % e) # TODO: Move this into sympy.matricies. def _sympy_tensor_product(*matrices): """Compute the kronecker product of a sequence of sympy Matrices. """ from sympy.matrices.expressions.kronecker import matrix_kronecker_product return matrix_kronecker_product(*matrices) def _numpy_tensor_product(*product): """numpy version of tensor product of multiple arguments.""" if not np: raise ImportError answer = product[0] for item in product[1:]: answer = np.kron(answer, item) return answer def _scipy_sparse_tensor_product(*product): """scipy.sparse version of tensor product of multiple arguments.""" if not sparse: raise ImportError answer = product[0] for item in product[1:]: answer = sparse.kron(answer, item) # The final matrices will just be multiplied, so csr is a good final # sparse format. return sparse.csr_matrix(answer) def matrix_tensor_product(*product): """Compute the matrix tensor product of sympy/numpy/scipy.sparse matrices.""" if isinstance(product[0], MatrixBase): return _sympy_tensor_product(*product) elif isinstance(product[0], numpy_ndarray): return _numpy_tensor_product(*product) elif isinstance(product[0], scipy_sparse_matrix): return _scipy_sparse_tensor_product(*product) def _numpy_eye(n): """numpy version of complex eye.""" if not np: raise ImportError return np.matrix(np.eye(n, dtype='complex')) def _scipy_sparse_eye(n): """scipy.sparse version of complex eye.""" if not sparse: raise ImportError return sparse.eye(n, n, dtype='complex') def matrix_eye(n, **options): """Get the version of eye and tensor_product for a given format.""" format = options.get('format', 'sympy') if format == 'sympy': return eye(n) elif format == 'numpy': return _numpy_eye(n) elif format == 'scipy.sparse': return _scipy_sparse_eye(n) raise NotImplementedError('Invalid format: %r' % format) def _numpy_zeros(m, n, **options): """numpy version of zeros.""" dtype = options.get('dtype', 'float64') if not np: raise ImportError return np.zeros((m, n), dtype=dtype) def _scipy_sparse_zeros(m, n, **options): """scipy.sparse version of zeros.""" spmatrix = options.get('spmatrix', 'csr') dtype = options.get('dtype', 'float64') if not sparse: raise ImportError if spmatrix == 'lil': return sparse.lil_matrix((m, n), dtype=dtype) elif spmatrix == 'csr': return sparse.csr_matrix((m, n), dtype=dtype) def matrix_zeros(m, n, **options): """"Get a zeros matrix for a given format.""" format = options.get('format', 'sympy') dtype = options.get('dtype', 'float64') spmatrix = options.get('spmatrix', 'csr') if format == 'sympy': return zeros(m, n) elif format == 'numpy': return _numpy_zeros(m, n, **options) elif format == 'scipy.sparse': return _scipy_sparse_zeros(m, n, **options) raise NotImplementedError('Invaild format: %r' % format) def _numpy_matrix_to_zero(e): """Convert a numpy zero matrix to the zero scalar.""" if not np: raise ImportError test = np.zeros_like(e) if np.allclose(e, test): return 0.0 else: return e def _scipy_sparse_matrix_to_zero(e): """Convert a scipy.sparse zero matrix to the zero scalar.""" if not np: raise ImportError edense = e.todense() test = np.zeros_like(edense) if np.allclose(edense, test): return 0.0 else: return e def matrix_to_zero(e): """Convert a zero matrix to the scalar zero.""" if isinstance(e, MatrixBase): if zeros(*e.shape) == e: e = Integer(0) elif isinstance(e, numpy_ndarray): e = _numpy_matrix_to_zero(e) elif isinstance(e, scipy_sparse_matrix): e = _scipy_sparse_matrix_to_zero(e) return e

cddd6db8223b4a4bc5f8ae6eea9c5e504197ef96ea0543ddeb719abec9799345

from sympy import Rational, pi, sqrt, sympify, S from sympy.physics.units.quantities import Quantity from sympy.physics.units.dimensions import ( acceleration, action, amount_of_substance, capacitance, charge, conductance, current, energy, force, frequency, information, impedance, inductance, length, luminous_intensity, magnetic_density, magnetic_flux, mass, power, pressure, temperature, time, velocity, voltage) from sympy.physics.units.dimensions import dimsys_default, Dimension from sympy.physics.units.prefixes import ( centi, deci, kilo, micro, milli, nano, pico, kibi, mebi, gibi, tebi, pebi, exbi) One = S.One #### UNITS #### # Dimensionless: percent = percents = Quantity("percent") percent.set_dimension(One) percent.set_scale_factor(Rational(1, 100)) permille = Quantity("permille") permille.set_dimension(One) permille.set_scale_factor(Rational(1, 1000)) # Angular units (dimensionless) rad = radian = radians = Quantity("radian") radian.set_dimension(One) radian.set_scale_factor(One) deg = degree = degrees = Quantity("degree", abbrev="deg") degree.set_dimension(One) degree.set_scale_factor(pi/180) sr = steradian = steradians = Quantity("steradian", abbrev="sr") steradian.set_dimension(One) steradian.set_scale_factor(One) mil = angular_mil = angular_mils = Quantity("angular_mil", abbrev="mil") angular_mil.set_dimension(One) angular_mil.set_scale_factor(2*pi/6400) # Base units: m = meter = meters = Quantity("meter", abbrev="m") meter.set_dimension(length) meter.set_scale_factor(One) # NOTE: the `kilogram` has scale factor of 1 in SI. # The current state of the code assumes SI unit dimensions, in # the future this module will be modified in order to be unit system-neutral # (that is, support all kinds of unit systems). kg = kilogram = kilograms = Quantity("kilogram", abbrev="kg") kilogram.set_dimension(mass) kilogram.set_scale_factor(One) s = second = seconds = Quantity("second", abbrev="s") second.set_dimension(time) second.set_scale_factor(One) A = ampere = amperes = Quantity("ampere", abbrev='A') ampere.set_dimension(current) ampere.set_scale_factor(One) K = kelvin = kelvins = Quantity("kelvin", abbrev='K') kelvin.set_dimension(temperature) kelvin.set_scale_factor(One) mol = mole = moles = Quantity("mole", abbrev="mol") mole.set_dimension(amount_of_substance) mole.set_scale_factor(One) cd = candela = candelas = Quantity("candela", abbrev="cd") candela.set_dimension(luminous_intensity) candela.set_scale_factor(One) g = gram = grams = Quantity("gram", abbrev="g") gram.set_dimension(mass) gram.set_scale_factor(kilogram/kilo) mg = milligram = milligrams = Quantity("milligram", abbrev="mg") milligram.set_dimension(mass) milligram.set_scale_factor(milli*gram) ug = microgram = micrograms = Quantity("microgram", abbrev="ug") microgram.set_dimension(mass) microgram.set_scale_factor(micro*gram) # derived units newton = newtons = N = Quantity("newton", abbrev="N") newton.set_dimension(force) newton.set_scale_factor(kilogram*meter/second**2) joule = joules = J = Quantity("joule", abbrev="J") joule.set_dimension(energy) joule.set_scale_factor(newton*meter) watt = watts = W = Quantity("watt", abbrev="W") watt.set_dimension(power) watt.set_scale_factor(joule/second) pascal = pascals = Pa = pa = Quantity("pascal", abbrev="Pa") pascal.set_dimension(pressure) pascal.set_scale_factor(newton/meter**2) hertz = hz = Hz = Quantity("hertz", abbrev="Hz") hertz.set_dimension(frequency) hertz.set_scale_factor(One) # MKSA extension to MKS: derived units coulomb = coulombs = C = Quantity("coulomb", abbrev='C') coulomb.set_dimension(charge) coulomb.set_scale_factor(One) volt = volts = v = V = Quantity("volt", abbrev='V') volt.set_dimension(voltage) volt.set_scale_factor(joule/coulomb) ohm = ohms = Quantity("ohm", abbrev='ohm') ohm.set_dimension(impedance) ohm.set_scale_factor(volt/ampere) siemens = S = mho = mhos = Quantity("siemens", abbrev='S') siemens.set_dimension(conductance) siemens.set_scale_factor(ampere/volt) farad = farads = F = Quantity("farad", abbrev='F') farad.set_dimension(capacitance) farad.set_scale_factor(coulomb/volt) henry = henrys = H = Quantity("henry", abbrev='H') henry.set_dimension(inductance) henry.set_scale_factor(volt*second/ampere) tesla = teslas = T = Quantity("tesla", abbrev='T') tesla.set_dimension(magnetic_density) tesla.set_scale_factor(volt*second/meter**2) weber = webers = Wb = wb = Quantity("weber", abbrev='Wb') weber.set_dimension(magnetic_flux) weber.set_scale_factor(joule/ampere) # Other derived units: optical_power = dioptre = D = Quantity("dioptre") dioptre.set_dimension(1/length) dioptre.set_scale_factor(1/meter) lux = lx = Quantity("lux") lux.set_dimension(luminous_intensity/length**2) lux.set_scale_factor(steradian*candela/meter**2) # katal is the SI unit of catalytic activity katal = kat = Quantity("katal") katal.set_dimension(amount_of_substance/time) katal.set_scale_factor(mol/second) # gray is the SI unit of absorbed dose gray = Gy = Quantity("gray") gray.set_dimension(energy/mass) gray.set_scale_factor(meter**2/second**2) # becquerel is the SI unit of radioactivity becquerel = Bq = Quantity("becquerel") becquerel.set_dimension(1/time) becquerel.set_scale_factor(1/second) # Common length units km = kilometer = kilometers = Quantity("kilometer", abbrev="km") kilometer.set_dimension(length) kilometer.set_scale_factor(kilo*meter) dm = decimeter = decimeters = Quantity("decimeter", abbrev="dm") decimeter.set_dimension(length) decimeter.set_scale_factor(deci*meter) cm = centimeter = centimeters = Quantity("centimeter", abbrev="cm") centimeter.set_dimension(length) centimeter.set_scale_factor(centi*meter) mm = millimeter = millimeters = Quantity("millimeter", abbrev="mm") millimeter.set_dimension(length) millimeter.set_scale_factor(milli*meter) um = micrometer = micrometers = micron = microns = Quantity("micrometer", abbrev="um") micrometer.set_dimension(length) micrometer.set_scale_factor(micro*meter) nm = nanometer = nanometers = Quantity("nanometer", abbrev="nn") nanometer.set_dimension(length) nanometer.set_scale_factor(nano*meter) pm = picometer = picometers = Quantity("picometer", abbrev="pm") picometer.set_dimension(length) picometer.set_scale_factor(pico*meter) ft = foot = feet = Quantity("foot", abbrev="ft") foot.set_dimension(length) foot.set_scale_factor(Rational(3048, 10000)*meter) inch = inches = Quantity("inch") inch.set_dimension(length) inch.set_scale_factor(foot/12) yd = yard = yards = Quantity("yard", abbrev="yd") yard.set_dimension(length) yard.set_scale_factor(3*feet) mi = mile = miles = Quantity("mile") mile.set_dimension(length) mile.set_scale_factor(5280*feet) nmi = nautical_mile = nautical_miles = Quantity("nautical_mile") nautical_mile.set_dimension(length) nautical_mile.set_scale_factor(6076*feet) # Common volume and area units l = liter = liters = Quantity("liter") liter.set_dimension(length**3) liter.set_scale_factor(meter**3 / 1000) dl = deciliter = deciliters = Quantity("deciliter") deciliter.set_dimension(length**3) deciliter.set_scale_factor(liter / 10) cl = centiliter = centiliters = Quantity("centiliter") centiliter.set_dimension(length**3) centiliter.set_scale_factor(liter / 100) ml = milliliter = milliliters = Quantity("milliliter") milliliter.set_dimension(length**3) milliliter.set_scale_factor(liter / 1000) # Common time units ms = millisecond = milliseconds = Quantity("millisecond", abbrev="ms") millisecond.set_dimension(time) millisecond.set_scale_factor(milli*second) us = microsecond = microseconds = Quantity("microsecond", abbrev="us") microsecond.set_dimension(time) microsecond.set_scale_factor(micro*second) ns = nanosecond = nanoseconds = Quantity("nanosecond", abbrev="ns") nanosecond.set_dimension(time) nanosecond.set_scale_factor(nano*second) ps = picosecond = picoseconds = Quantity("picosecond", abbrev="ps") picosecond.set_dimension(time) picosecond.set_scale_factor(pico*second) minute = minutes = Quantity("minute") minute.set_dimension(time) minute.set_scale_factor(60*second) h = hour = hours = Quantity("hour") hour.set_dimension(time) hour.set_scale_factor(60*minute) day = days = Quantity("day") day.set_dimension(time) day.set_scale_factor(24*hour) anomalistic_year = anomalistic_years = Quantity("anomalistic_year") anomalistic_year.set_dimension(time) anomalistic_year.set_scale_factor(365.259636*day) sidereal_year = sidereal_years = Quantity("sidereal_year") sidereal_year.set_dimension(time) sidereal_year.set_scale_factor(31558149.540) tropical_year = tropical_years = Quantity("tropical_year") tropical_year.set_dimension(time) tropical_year.set_scale_factor(365.24219*day) common_year = common_years = Quantity("common_year") common_year.set_dimension(time) common_year.set_scale_factor(365*day) julian_year = julian_years = Quantity("julian_year") julian_year.set_dimension(time) julian_year.set_scale_factor((365 + One/4)*day) draconic_year = draconic_years = Quantity("draconic_year") draconic_year.set_dimension(time) draconic_year.set_scale_factor(346.62*day) gaussian_year = gaussian_years = Quantity("gaussian_year") gaussian_year.set_dimension(time) gaussian_year.set_scale_factor(365.2568983*day) full_moon_cycle = full_moon_cycles = Quantity("full_moon_cycle") full_moon_cycle.set_dimension(time) full_moon_cycle.set_scale_factor(411.78443029*day) year = years = tropical_year #### CONSTANTS #### # Newton constant G = gravitational_constant = Quantity("gravitational_constant", abbrev="G") gravitational_constant.set_dimension(length**3*mass**-1*time**-2) gravitational_constant.set_scale_factor(6.67408e-11*m**3/(kg*s**2)) # speed of light c = speed_of_light = Quantity("speed_of_light", abbrev="c") speed_of_light.set_dimension(velocity) speed_of_light.set_scale_factor(299792458*meter/second) # Reduced Planck constant hbar = Quantity("hbar", abbrev="hbar") hbar.set_dimension(action) hbar.set_scale_factor(1.05457266e-34*joule*second) # Planck constant planck = Quantity("planck", abbrev="h") planck.set_dimension(action) planck.set_scale_factor(2*pi*hbar) # Electronvolt eV = electronvolt = electronvolts = Quantity("electronvolt", abbrev="eV") electronvolt.set_dimension(energy) electronvolt.set_scale_factor(1.60219e-19*joule) # Avogadro number avogadro_number = Quantity("avogadro_number") avogadro_number.set_dimension(One) avogadro_number.set_scale_factor(6.022140857e23) # Avogadro constant avogadro = avogadro_constant = Quantity("avogadro_constant") avogadro_constant.set_dimension(amount_of_substance**-1) avogadro_constant.set_scale_factor(avogadro_number / mol) # Boltzmann constant boltzmann = boltzmann_constant = Quantity("boltzmann_constant") boltzmann_constant.set_dimension(energy/temperature) boltzmann_constant.set_scale_factor(1.38064852e-23*joule/kelvin) # Stefan-Boltzmann constant stefan = stefan_boltzmann_constant = Quantity("stefan_boltzmann_constant") stefan_boltzmann_constant.set_dimension(energy*time**-1*length**-2*temperature**-4) stefan_boltzmann_constant.set_scale_factor(5.670367e-8*joule/(s*m**2*kelvin**4)) # Atomic mass amu = amus = atomic_mass_unit = atomic_mass_constant = Quantity("atomic_mass_constant") atomic_mass_constant.set_dimension(mass) atomic_mass_constant.set_scale_factor(1.660539040e-24*gram) # Molar gas constant R = molar_gas_constant = Quantity("molar_gas_constant", abbrev="R") molar_gas_constant.set_dimension(energy/(temperature * amount_of_substance)) molar_gas_constant.set_scale_factor(8.3144598*joule/kelvin/mol) # Faraday constant faraday_constant = Quantity("faraday_constant") faraday_constant.set_dimension(charge/amount_of_substance) faraday_constant.set_scale_factor(96485.33289*C/mol) # Josephson constant josephson_constant = Quantity("josephson_constant", abbrev="K_j") josephson_constant.set_dimension(frequency/voltage) josephson_constant.set_scale_factor(483597.8525e9*hertz/V) # Von Klitzing constant von_klitzing_constant = Quantity("von_klitzing_constant", abbrev="R_k") von_klitzing_constant.set_dimension(voltage/current) von_klitzing_constant.set_scale_factor(25812.8074555*ohm) # Acceleration due to gravity (on the Earth surface) gee = gees = acceleration_due_to_gravity = Quantity("acceleration_due_to_gravity", abbrev="g") acceleration_due_to_gravity.set_dimension(acceleration) acceleration_due_to_gravity.set_scale_factor(9.80665*meter/second**2) # magnetic constant: u0 = magnetic_constant = vacuum_permeability = Quantity("magnetic_constant") magnetic_constant.set_dimension(force/current**2) magnetic_constant.set_scale_factor(4*pi/10**7 * newton/ampere**2) # electric constat: e0 = electric_constant = vacuum_permittivity = Quantity("vacuum_permittivity") vacuum_permittivity.set_dimension(capacitance/length) vacuum_permittivity.set_scale_factor(1/(u0 * c**2)) # vacuum impedance: Z0 = vacuum_impedance = Quantity("vacuum_impedance", abbrev='Z_0') vacuum_impedance.set_dimension(impedance) vacuum_impedance.set_scale_factor(u0 * c) # Coulomb's constant: coulomb_constant = coulombs_constant = electric_force_constant = Quantity("coulomb_constant", abbrev="k_e") coulomb_constant.set_dimension(force*length**2/charge**2) coulomb_constant.set_scale_factor(1/(4*pi*vacuum_permittivity)) atmosphere = atmospheres = atm = Quantity("atmosphere", abbrev="atm") atmosphere.set_dimension(pressure) atmosphere.set_scale_factor(101325 * pascal) kPa = kilopascal = Quantity("kilopascal", abbrev="kPa") kilopascal.set_dimension(pressure) kilopascal.set_scale_factor(kilo*Pa) bar = bars = Quantity("bar", abbrev="bar") bar.set_dimension(pressure) bar.set_scale_factor(100*kPa) pound = pounds = Quantity("pound") # exact pound.set_dimension(mass) pound.set_scale_factor(Rational(45359237, 100000000) * kg) psi = Quantity("psi") psi.set_dimension(pressure) psi.set_scale_factor(pound * gee / inch ** 2) dHg0 = 13.5951 # approx value at 0 C mmHg = torr = Quantity("mmHg") mmHg.set_dimension(pressure) mmHg.set_scale_factor(dHg0 * acceleration_due_to_gravity * kilogram / meter**2) mmu = mmus = milli_mass_unit = Quantity("milli_mass_unit") milli_mass_unit.set_dimension(mass) milli_mass_unit.set_scale_factor(atomic_mass_unit/1000) quart = quarts = Quantity("quart") quart.set_dimension(length**3) quart.set_scale_factor(Rational(231, 4) * inch**3) # Other convenient units and magnitudes ly = lightyear = lightyears = Quantity("lightyear", abbrev="ly") lightyear.set_dimension(length) lightyear.set_scale_factor(speed_of_light*julian_year) au = astronomical_unit = astronomical_units = Quantity("astronomical_unit", abbrev="AU") astronomical_unit.set_dimension(length) astronomical_unit.set_scale_factor(149597870691*meter) # Fundamental Planck units: planck_mass = Quantity("planck_mass", abbrev="m_P") planck_mass.set_dimension(mass) planck_mass.set_scale_factor(sqrt(hbar*speed_of_light/G)) planck_time = Quantity("planck_time", abbrev="t_P") planck_time.set_dimension(time) planck_time.set_scale_factor(sqrt(hbar*G/speed_of_light**5)) planck_temperature = Quantity("planck_temperature", abbrev="T_P") planck_temperature.set_dimension(temperature) planck_temperature.set_scale_factor(sqrt(hbar*speed_of_light**5/G/boltzmann**2)) planck_length = Quantity("planck_length", abbrev="l_P") planck_length.set_dimension(length) planck_length.set_scale_factor(sqrt(hbar*G/speed_of_light**3)) planck_charge = Quantity("planck_charge", abbrev="q_P") planck_charge.set_dimension(charge) planck_charge.set_scale_factor(sqrt(4*pi*electric_constant*hbar*speed_of_light)) # Derived Planck units: planck_area = Quantity("planck_area") planck_area.set_dimension(length**2) planck_area.set_scale_factor(planck_length**2) planck_volume = Quantity("planck_volume") planck_volume.set_dimension(length**3) planck_volume.set_scale_factor(planck_length**3) planck_momentum = Quantity("planck_momentum") planck_momentum.set_dimension(mass*velocity) planck_momentum.set_scale_factor(planck_mass * speed_of_light) planck_energy = Quantity("planck_energy", abbrev="E_P") planck_energy.set_dimension(energy) planck_energy.set_scale_factor(planck_mass * speed_of_light**2) planck_force = Quantity("planck_force", abbrev="F_P") planck_force.set_dimension(force) planck_force.set_scale_factor(planck_energy / planck_length) planck_power = Quantity("planck_power", abbrev="P_P") planck_power.set_dimension(power) planck_power.set_scale_factor(planck_energy / planck_time) planck_density = Quantity("planck_density", abbrev="rho_P") planck_density.set_dimension(mass/length**3) planck_density.set_scale_factor(planck_mass / planck_length**3) planck_energy_density = Quantity("planck_energy_density", abbrev="rho^E_P") planck_energy_density.set_dimension(energy / length**3) planck_energy_density.set_scale_factor(planck_energy / planck_length**3) planck_intensity = Quantity("planck_intensity", abbrev="I_P") planck_intensity.set_dimension(mass * time**(-3)) planck_intensity.set_scale_factor(planck_energy_density * speed_of_light) planck_angular_frequency = Quantity("planck_angular_frequency", abbrev="omega_P") planck_angular_frequency.set_dimension(1 / time) planck_angular_frequency.set_scale_factor(1 / planck_time) planck_pressure = Quantity("planck_pressure", abbrev="p_P") planck_pressure.set_dimension(pressure) planck_pressure.set_scale_factor(planck_force / planck_length**2) planck_current = Quantity("planck_current", abbrev="I_P") planck_current.set_dimension(current) planck_current.set_scale_factor(planck_charge / planck_time) planck_voltage = Quantity("planck_voltage", abbrev="V_P") planck_voltage.set_dimension(voltage) planck_voltage.set_scale_factor(planck_energy / planck_charge) planck_impedance = Quantity("planck_impedance", abbrev="Z_P") planck_impedance.set_dimension(impedance) planck_impedance.set_scale_factor(planck_voltage / planck_current) planck_acceleration = Quantity("planck_acceleration", abbrev="a_P") planck_acceleration.set_dimension(acceleration) planck_acceleration.set_scale_factor(speed_of_light / planck_time) # Information theory units: bit = bits = Quantity("bit") bit.set_dimension(information) bit.set_scale_factor(One) byte = bytes = Quantity("byte") byte.set_dimension(information) byte.set_scale_factor(8*bit) kibibyte = kibibytes = Quantity("kibibyte") kibibyte.set_dimension(information) kibibyte.set_scale_factor(kibi*byte) mebibyte = mebibytes = Quantity("mebibyte") mebibyte.set_dimension(information) mebibyte.set_scale_factor(mebi*byte) gibibyte = gibibytes = Quantity("gibibyte") gibibyte.set_dimension(information) gibibyte.set_scale_factor(gibi*byte) tebibyte = tebibytes = Quantity("tebibyte") tebibyte.set_dimension(information) tebibyte.set_scale_factor(tebi*byte) pebibyte = pebibytes = Quantity("pebibyte") pebibyte.set_dimension(information) pebibyte.set_scale_factor(pebi*byte) exbibyte = exbibytes = Quantity("exbibyte") exbibyte.set_dimension(information) exbibyte.set_scale_factor(exbi*byte) # check that scale factors are the right SI dimensions: for _scale_factor, _dimension in zip( Quantity.SI_quantity_scale_factors.values(), Quantity.SI_quantity_dimension_map.values()): dimex = Quantity.get_dimensional_expr(_scale_factor) if dimex != 1: if not dimsys_default.equivalent_dims(_dimension, Dimension(dimex)): raise ValueError("quantity value and dimension mismatch") del _scale_factor, _dimension

3e6d870448209e3bda0b6f7b1c90ad791615f5ccf76a32c966123fd18c3367d2

from sympy.core.backend import (S, sympify, expand, sqrt, Add, zeros, ImmutableMatrix as Matrix) from sympy import trigsimp from sympy.core.compatibility import unicode from sympy.utilities.misc import filldedent __all__ = ['Vector'] class Vector(object): """The class used to define vectors. It along with ReferenceFrame are the building blocks of describing a classical mechanics system in PyDy and sympy.physics.vector. Attributes ========== simp : Boolean Let certain methods use trigsimp on their outputs """ simp = False def __init__(self, inlist): """This is the constructor for the Vector class. You shouldn't be calling this, it should only be used by other functions. You should be treating Vectors like you would with if you were doing the math by hand, and getting the first 3 from the standard basis vectors from a ReferenceFrame. The only exception is to create a zero vector: zv = Vector(0) """ self.args = [] if inlist == 0: inlist = [] if isinstance(inlist, dict): d = inlist else: d = {} for inp in inlist: if inp[1] in d: d[inp[1]] += inp[0] else: d[inp[1]] = inp[0] for k, v in d.items(): if v != Matrix([0, 0, 0]): self.args.append((v, k)) def __hash__(self): return hash(tuple(self.args)) def __add__(self, other): """The add operator for Vector. """ if other == 0: return self other = _check_vector(other) return Vector(self.args + other.args) def __and__(self, other): """Dot product of two vectors. Returns a scalar, the dot product of the two Vectors Parameters ========== other : Vector The Vector which we are dotting with Examples ======== >>> from sympy.physics.vector import ReferenceFrame, dot >>> from sympy import symbols >>> q1 = symbols('q1') >>> N = ReferenceFrame('N') >>> dot(N.x, N.x) 1 >>> dot(N.x, N.y) 0 >>> A = N.orientnew('A', 'Axis', [q1, N.x]) >>> dot(N.y, A.y) cos(q1) """ from sympy.physics.vector.dyadic import Dyadic if isinstance(other, Dyadic): return NotImplemented other = _check_vector(other) out = S(0) for i, v1 in enumerate(self.args): for j, v2 in enumerate(other.args): out += ((v2[0].T) * (v2[1].dcm(v1[1])) * (v1[0]))[0] if Vector.simp: return trigsimp(sympify(out), recursive=True) else: return sympify(out) def __div__(self, other): """This uses mul and inputs self and 1 divided by other. """ return self.__mul__(sympify(1) / other) __truediv__ = __div__ def __eq__(self, other): """Tests for equality. It is very import to note that this is only as good as the SymPy equality test; False does not always mean they are not equivalent Vectors. If other is 0, and self is empty, returns True. If other is 0 and self is not empty, returns False. If none of the above, only accepts other as a Vector. """ if other == 0: other = Vector(0) try: other = _check_vector(other) except TypeError: return False if (self.args == []) and (other.args == []): return True elif (self.args == []) or (other.args == []): return False frame = self.args[0][1] for v in frame: if expand((self - other) & v) != 0: return False return True def __mul__(self, other): """Multiplies the Vector by a sympifyable expression. Parameters ========== other : Sympifyable The scalar to multiply this Vector with Examples ======== >>> from sympy.physics.vector import ReferenceFrame >>> from sympy import Symbol >>> N = ReferenceFrame('N') >>> b = Symbol('b') >>> V = 10 * b * N.x >>> print(V) 10*b*N.x """ newlist = [v for v in self.args] for i, v in enumerate(newlist): newlist[i] = (sympify(other) * newlist[i][0], newlist[i][1]) return Vector(newlist) def __ne__(self, other): return not self == other def __neg__(self): return self * -1 def __or__(self, other): """Outer product between two Vectors. A rank increasing operation, which returns a Dyadic from two Vectors Parameters ========== other : Vector The Vector to take the outer product with Examples ======== >>> from sympy.physics.vector import ReferenceFrame, outer >>> N = ReferenceFrame('N') >>> outer(N.x, N.x) (N.x|N.x) """ from sympy.physics.vector.dyadic import Dyadic other = _check_vector(other) ol = Dyadic(0) for i, v in enumerate(self.args): for i2, v2 in enumerate(other.args): # it looks this way because if we are in the same frame and # use the enumerate function on the same frame in a nested # fashion, then bad things happen ol += Dyadic([(v[0][0] * v2[0][0], v[1].x, v2[1].x)]) ol += Dyadic([(v[0][0] * v2[0][1], v[1].x, v2[1].y)]) ol += Dyadic([(v[0][0] * v2[0][2], v[1].x, v2[1].z)]) ol += Dyadic([(v[0][1] * v2[0][0], v[1].y, v2[1].x)]) ol += Dyadic([(v[0][1] * v2[0][1], v[1].y, v2[1].y)]) ol += Dyadic([(v[0][1] * v2[0][2], v[1].y, v2[1].z)]) ol += Dyadic([(v[0][2] * v2[0][0], v[1].z, v2[1].x)]) ol += Dyadic([(v[0][2] * v2[0][1], v[1].z, v2[1].y)]) ol += Dyadic([(v[0][2] * v2[0][2], v[1].z, v2[1].z)]) return ol def _latex(self, printer=None): """Latex Printing method. """ from sympy.physics.vector.printing import VectorLatexPrinter ar = self.args # just to shorten things if len(ar) == 0: return str(0) ol = [] # output list, to be concatenated to a string for i, v in enumerate(ar): for j in 0, 1, 2: # if the coef of the basis vector is 1, we skip the 1 if ar[i][0][j] == 1: ol.append(' + ' + ar[i][1].latex_vecs[j]) # if the coef of the basis vector is -1, we skip the 1 elif ar[i][0][j] == -1: ol.append(' - ' + ar[i][1].latex_vecs[j]) elif ar[i][0][j] != 0: # If the coefficient of the basis vector is not 1 or -1; # also, we might wrap it in parentheses, for readability. arg_str = VectorLatexPrinter().doprint(ar[i][0][j]) if isinstance(ar[i][0][j], Add): arg_str = "(%s)" % arg_str if arg_str[0] == '-': arg_str = arg_str[1:] str_start = ' - ' else: str_start = ' + ' ol.append(str_start + arg_str + ar[i][1].latex_vecs[j]) outstr = ''.join(ol) if outstr.startswith(' + '): outstr = outstr[3:] elif outstr.startswith(' '): outstr = outstr[1:] return outstr def _pretty(self, printer=None): """Pretty Printing method. """ from sympy.physics.vector.printing import VectorPrettyPrinter from sympy.printing.pretty.stringpict import prettyForm e = self class Fake(object): def render(self, *args, **kwargs): ar = e.args # just to shorten things if len(ar) == 0: return unicode(0) settings = printer._settings if printer else {} vp = printer if printer else VectorPrettyPrinter(settings) pforms = [] # output list, to be concatenated to a string for i, v in enumerate(ar): for j in 0, 1, 2: # if the coef of the basis vector is 1, we skip the 1 if ar[i][0][j] == 1: pform = vp._print(ar[i][1].pretty_vecs[j]) # if the coef of the basis vector is -1, we skip the 1 elif ar[i][0][j] == -1: pform = vp._print(ar[i][1].pretty_vecs[j]) pform = prettyForm(*pform.left(" - ")) bin = prettyForm.NEG pform = prettyForm(binding=bin, *pform) elif ar[i][0][j] != 0: # If the basis vector coeff is not 1 or -1, # we might wrap it in parentheses, for readability. pform = vp._print(ar[i][0][j]) if isinstance(ar[i][0][j], Add): tmp = pform.parens() pform = prettyForm(tmp[0], tmp[1]) pform = prettyForm(*pform.right(" ", ar[i][1].pretty_vecs[j])) else: continue pforms.append(pform) pform = prettyForm.__add__(*pforms) kwargs["wrap_line"] = kwargs.get("wrap_line") kwargs["num_columns"] = kwargs.get("num_columns") out_str = pform.render(*args, **kwargs) mlines = [line.rstrip() for line in out_str.split("\n")] return "\n".join(mlines) return Fake() def __ror__(self, other): """Outer product between two Vectors. A rank increasing operation, which returns a Dyadic from two Vectors Parameters ========== other : Vector The Vector to take the outer product with Examples ======== >>> from sympy.physics.vector import ReferenceFrame, outer >>> N = ReferenceFrame('N') >>> outer(N.x, N.x) (N.x|N.x) """ from sympy.physics.vector.dyadic import Dyadic other = _check_vector(other) ol = Dyadic(0) for i, v in enumerate(other.args): for i2, v2 in enumerate(self.args): # it looks this way because if we are in the same frame and # use the enumerate function on the same frame in a nested # fashion, then bad things happen ol += Dyadic([(v[0][0] * v2[0][0], v[1].x, v2[1].x)]) ol += Dyadic([(v[0][0] * v2[0][1], v[1].x, v2[1].y)]) ol += Dyadic([(v[0][0] * v2[0][2], v[1].x, v2[1].z)]) ol += Dyadic([(v[0][1] * v2[0][0], v[1].y, v2[1].x)]) ol += Dyadic([(v[0][1] * v2[0][1], v[1].y, v2[1].y)]) ol += Dyadic([(v[0][1] * v2[0][2], v[1].y, v2[1].z)]) ol += Dyadic([(v[0][2] * v2[0][0], v[1].z, v2[1].x)]) ol += Dyadic([(v[0][2] * v2[0][1], v[1].z, v2[1].y)]) ol += Dyadic([(v[0][2] * v2[0][2], v[1].z, v2[1].z)]) return ol def __rsub__(self, other): return (-1 * self) + other def __str__(self, printer=None, order=True): """Printing method. """ from sympy.physics.vector.printing import VectorStrPrinter if not order or len(self.args) == 1: ar = list(self.args) elif len(self.args) == 0: return str(0) else: d = {v[1]: v[0] for v in self.args} keys = sorted(d.keys(), key=lambda x: x.index) ar = [] for key in keys: ar.append((d[key], key)) ol = [] # output list, to be concatenated to a string for i, v in enumerate(ar): for j in 0, 1, 2: # if the coef of the basis vector is 1, we skip the 1 if ar[i][0][j] == 1: ol.append(' + ' + ar[i][1].str_vecs[j]) # if the coef of the basis vector is -1, we skip the 1 elif ar[i][0][j] == -1: ol.append(' - ' + ar[i][1].str_vecs[j]) elif ar[i][0][j] != 0: # If the coefficient of the basis vector is not 1 or -1; # also, we might wrap it in parentheses, for readability. arg_str = VectorStrPrinter().doprint(ar[i][0][j]) if isinstance(ar[i][0][j], Add): arg_str = "(%s)" % arg_str if arg_str[0] == '-': arg_str = arg_str[1:] str_start = ' - ' else: str_start = ' + ' ol.append(str_start + arg_str + '*' + ar[i][1].str_vecs[j]) outstr = ''.join(ol) if outstr.startswith(' + '): outstr = outstr[3:] elif outstr.startswith(' '): outstr = outstr[1:] return outstr def __sub__(self, other): """The subraction operator. """ return self.__add__(other * -1) def __xor__(self, other): """The cross product operator for two Vectors. Returns a Vector, expressed in the same ReferenceFrames as self. Parameters ========== other : Vector The Vector which we are crossing with Examples ======== >>> from sympy.physics.vector import ReferenceFrame, Vector >>> from sympy import symbols >>> q1 = symbols('q1') >>> N = ReferenceFrame('N') >>> N.x ^ N.y N.z >>> A = N.orientnew('A', 'Axis', [q1, N.x]) >>> A.x ^ N.y N.z >>> N.y ^ A.x - sin(q1)*A.y - cos(q1)*A.z """ from sympy.physics.vector.dyadic import Dyadic if isinstance(other, Dyadic): return NotImplemented other = _check_vector(other) if other.args == []: return Vector(0) def _det(mat): """This is needed as a little method for to find the determinant of a list in python; needs to work for a 3x3 list. SymPy's Matrix won't take in Vector, so need a custom function. You shouldn't be calling this. """ return (mat[0][0] * (mat[1][1] * mat[2][2] - mat[1][2] * mat[2][1]) + mat[0][1] * (mat[1][2] * mat[2][0] - mat[1][0] * mat[2][2]) + mat[0][2] * (mat[1][0] * mat[2][1] - mat[1][1] * mat[2][0])) outlist = [] ar = other.args # For brevity for i, v in enumerate(ar): tempx = v[1].x tempy = v[1].y tempz = v[1].z tempm = ([[tempx, tempy, tempz], [self & tempx, self & tempy, self & tempz], [Vector([ar[i]]) & tempx, Vector([ar[i]]) & tempy, Vector([ar[i]]) & tempz]]) outlist += _det(tempm).args return Vector(outlist) # We don't define _repr_png_ here because it would add a large amount of # data to any notebook containing SymPy expressions, without adding # anything useful to the notebook. It can still enabled manually, e.g., # for the qtconsole, with init_printing(). def _repr_latex_(self): """ IPython/Jupyter LaTeX printing To change the behavior of this (e.g., pass in some settings to LaTeX), use init_printing(). init_printing() will also enable LaTeX printing for built in numeric types like ints and container types that contain SymPy objects, like lists and dictionaries of expressions. """ from sympy.printing.latex import latex s = latex(self, mode='plain') return "$\\displaystyle %s$" % s _repr_latex_orig = _repr_latex_ _sympystr = __str__ _sympyrepr = _sympystr __repr__ = __str__ __radd__ = __add__ __rand__ = __and__ __rmul__ = __mul__ def separate(self): """ The constituents of this vector in different reference frames, as per its definition. Returns a dict mapping each ReferenceFrame to the corresponding constituent Vector. Examples ======== >>> from sympy.physics.vector import ReferenceFrame >>> R1 = ReferenceFrame('R1') >>> R2 = ReferenceFrame('R2') >>> v = R1.x + R2.x >>> v.separate() == {R1: R1.x, R2: R2.x} True """ components = {} for x in self.args: components[x[1]] = Vector([x]) return components def dot(self, other): return self & other dot.__doc__ = __and__.__doc__ def cross(self, other): return self ^ other cross.__doc__ = __xor__.__doc__ def outer(self, other): return self | other outer.__doc__ = __or__.__doc__ def diff(self, var, frame, var_in_dcm=True): """Returns the partial derivative of the vector with respect to a variable in the provided reference frame. Parameters ========== var : Symbol What the partial derivative is taken with respect to. frame : ReferenceFrame The reference frame that the partial derivative is taken in. var_in_dcm : boolean If true, the differentiation algorithm assumes that the variable may be present in any of the direction cosine matrices that relate the frame to the frames of any component of the vector. But if it is known that the variable is not present in the direction cosine matrices, false can be set to skip full reexpression in the desired frame. Examples ======== >>> from sympy import Symbol >>> from sympy.physics.vector import dynamicsymbols, ReferenceFrame >>> from sympy.physics.vector import Vector >>> Vector.simp = True >>> t = Symbol('t') >>> q1 = dynamicsymbols('q1') >>> N = ReferenceFrame('N') >>> A = N.orientnew('A', 'Axis', [q1, N.y]) >>> A.x.diff(t, N) - q1'*A.z >>> B = ReferenceFrame('B') >>> u1, u2 = dynamicsymbols('u1, u2') >>> v = u1 * A.x + u2 * B.y >>> v.diff(u2, N, var_in_dcm=False) B.y """ from sympy.physics.vector.frame import _check_frame var = sympify(var) _check_frame(frame) inlist = [] for vector_component in self.args: measure_number = vector_component[0] component_frame = vector_component[1] if component_frame == frame: inlist += [(measure_number.diff(var), frame)] else: # If the direction cosine matrix relating the component frame # with the derivative frame does not contain the variable. if not var_in_dcm or (frame.dcm(component_frame).diff(var) == zeros(3, 3)): inlist += [(measure_number.diff(var), component_frame)] else: # else express in the frame reexp_vec_comp = Vector([vector_component]).express(frame) deriv = reexp_vec_comp.args[0][0].diff(var) inlist += Vector([(deriv, frame)]).express(component_frame).args return Vector(inlist) def express(self, otherframe, variables=False): """ Returns a Vector equivalent to this one, expressed in otherframe. Uses the global express method. Parameters ========== otherframe : ReferenceFrame The frame for this Vector to be described in variables : boolean If True, the coordinate symbols(if present) in this Vector are re-expressed in terms otherframe Examples ======== >>> from sympy.physics.vector import ReferenceFrame, Vector, dynamicsymbols >>> q1 = dynamicsymbols('q1') >>> N = ReferenceFrame('N') >>> A = N.orientnew('A', 'Axis', [q1, N.y]) >>> A.x.express(N) cos(q1)*N.x - sin(q1)*N.z """ from sympy.physics.vector import express return express(self, otherframe, variables=variables) def to_matrix(self, reference_frame): """Returns the matrix form of the vector with respect to the given frame. Parameters ---------- reference_frame : ReferenceFrame The reference frame that the rows of the matrix correspond to. Returns ------- matrix : ImmutableMatrix, shape(3,1) The matrix that gives the 1D vector. Examples ======== >>> from sympy import symbols >>> from sympy.physics.vector import ReferenceFrame >>> from sympy.physics.mechanics.functions import inertia >>> a, b, c = symbols('a, b, c') >>> N = ReferenceFrame('N') >>> vector = a * N.x + b * N.y + c * N.z >>> vector.to_matrix(N) Matrix([ [a], [b], [c]]) >>> beta = symbols('beta') >>> A = N.orientnew('A', 'Axis', (beta, N.x)) >>> vector.to_matrix(A) Matrix([ [ a], [ b*cos(beta) + c*sin(beta)], [-b*sin(beta) + c*cos(beta)]]) """ return Matrix([self.dot(unit_vec) for unit_vec in reference_frame]).reshape(3, 1) def doit(self, **hints): """Calls .doit() on each term in the Vector""" d = {} for v in self.args: d[v[1]] = v[0].applyfunc(lambda x: x.doit(**hints)) return Vector(d) def dt(self, otherframe): """ Returns a Vector which is the time derivative of the self Vector, taken in frame otherframe. Calls the global time_derivative method Parameters ========== otherframe : ReferenceFrame The frame to calculate the time derivative in """ from sympy.physics.vector import time_derivative return time_derivative(self, otherframe) def simplify(self): """Returns a simplified Vector.""" d = {} for v in self.args: d[v[1]] = v[0].simplify() return Vector(d) def subs(self, *args, **kwargs): """Substitution on the Vector. Examples ======== >>> from sympy.physics.vector import ReferenceFrame >>> from sympy import Symbol >>> N = ReferenceFrame('N') >>> s = Symbol('s') >>> a = N.x * s >>> a.subs({s: 2}) 2*N.x """ d = {} for v in self.args: d[v[1]] = v[0].subs(*args, **kwargs) return Vector(d) def magnitude(self): """Returns the magnitude (Euclidean norm) of self.""" return sqrt(self & self) def normalize(self): """Returns a Vector of magnitude 1, codirectional with self.""" return Vector(self.args + []) / self.magnitude() def applyfunc(self, f): """Apply a function to each component of a vector.""" if not callable(f): raise TypeError("`f` must be callable.") d = {} for v in self.args: d[v[1]] = v[0].applyfunc(f) return Vector(d) def free_symbols(self, reference_frame): """ Returns the free symbols in the measure numbers of the vector expressed in the given reference frame. Parameter ========= reference_frame : ReferenceFrame The frame with respect to which the free symbols of the given vector is to be determined. """ return self.to_matrix(reference_frame).free_symbols class VectorTypeError(TypeError): def __init__(self, other, want): msg = filldedent("Expected an instance of %s, but received object " "'%s' of %s." % (type(want), other, type(other))) super(VectorTypeError, self).__init__(msg) def _check_vector(other): if not isinstance(other, Vector): raise TypeError('A Vector must be supplied') return other

9e9b9812bfb03209505a678145dfd029b22dbccfe1009f00d685e3c851fc335a

from sympy.core.backend import sympify, Add, ImmutableMatrix as Matrix from sympy.core.compatibility import unicode from .printing import (VectorLatexPrinter, VectorPrettyPrinter, VectorStrPrinter) __all__ = ['Dyadic'] class Dyadic(object): """A Dyadic object. See: https://en.wikipedia.org/wiki/Dyadic_tensor Kane, T., Levinson, D. Dynamics Theory and Applications. 1985 McGraw-Hill A more powerful way to represent a rigid body's inertia. While it is more complex, by choosing Dyadic components to be in body fixed basis vectors, the resulting matrix is equivalent to the inertia tensor. """ def __init__(self, inlist): """ Just like Vector's init, you shouldn't call this unless creating a zero dyadic. zd = Dyadic(0) Stores a Dyadic as a list of lists; the inner list has the measure number and the two unit vectors; the outerlist holds each unique unit vector pair. """ self.args = [] if inlist == 0: inlist = [] while len(inlist) != 0: added = 0 for i, v in enumerate(self.args): if ((str(inlist[0][1]) == str(self.args[i][1])) and (str(inlist[0][2]) == str(self.args[i][2]))): self.args[i] = (self.args[i][0] + inlist[0][0], inlist[0][1], inlist[0][2]) inlist.remove(inlist[0]) added = 1 break if added != 1: self.args.append(inlist[0]) inlist.remove(inlist[0]) i = 0 # This code is to remove empty parts from the list while i < len(self.args): if ((self.args[i][0] == 0) | (self.args[i][1] == 0) | (self.args[i][2] == 0)): self.args.remove(self.args[i]) i -= 1 i += 1 def __add__(self, other): """The add operator for Dyadic. """ other = _check_dyadic(other) return Dyadic(self.args + other.args) def __and__(self, other): """The inner product operator for a Dyadic and a Dyadic or Vector. Parameters ========== other : Dyadic or Vector The other Dyadic or Vector to take the inner product with Examples ======== >>> from sympy.physics.vector import ReferenceFrame, outer >>> N = ReferenceFrame('N') >>> D1 = outer(N.x, N.y) >>> D2 = outer(N.y, N.y) >>> D1.dot(D2) (N.x|N.y) >>> D1.dot(N.y) N.x """ from sympy.physics.vector.vector import Vector, _check_vector if isinstance(other, Dyadic): other = _check_dyadic(other) ol = Dyadic(0) for i, v in enumerate(self.args): for i2, v2 in enumerate(other.args): ol += v[0] * v2[0] * (v[2] & v2[1]) * (v[1] | v2[2]) else: other = _check_vector(other) ol = Vector(0) for i, v in enumerate(self.args): ol += v[0] * v[1] * (v[2] & other) return ol def __div__(self, other): """Divides the Dyadic by a sympifyable expression. """ return self.__mul__(1 / other) __truediv__ = __div__ def __eq__(self, other): """Tests for equality. Is currently weak; needs stronger comparison testing """ if other == 0: other = Dyadic(0) other = _check_dyadic(other) if (self.args == []) and (other.args == []): return True elif (self.args == []) or (other.args == []): return False return set(self.args) == set(other.args) def __mul__(self, other): """Multiplies the Dyadic by a sympifyable expression. Parameters ========== other : Sympafiable The scalar to multiply this Dyadic with Examples ======== >>> from sympy.physics.vector import ReferenceFrame, outer >>> N = ReferenceFrame('N') >>> d = outer(N.x, N.x) >>> 5 * d 5*(N.x|N.x) """ newlist = [v for v in self.args] for i, v in enumerate(newlist): newlist[i] = (sympify(other) * newlist[i][0], newlist[i][1], newlist[i][2]) return Dyadic(newlist) def __ne__(self, other): return not self == other def __neg__(self): return self * -1 def _latex(self, printer=None): ar = self.args # just to shorten things if len(ar) == 0: return str(0) ol = [] # output list, to be concatenated to a string mlp = VectorLatexPrinter() for i, v in enumerate(ar): # if the coef of the dyadic is 1, we skip the 1 if ar[i][0] == 1: ol.append(' + ' + mlp.doprint(ar[i][1]) + r"\otimes " + mlp.doprint(ar[i][2])) # if the coef of the dyadic is -1, we skip the 1 elif ar[i][0] == -1: ol.append(' - ' + mlp.doprint(ar[i][1]) + r"\otimes " + mlp.doprint(ar[i][2])) # If the coefficient of the dyadic is not 1 or -1, # we might wrap it in parentheses, for readability. elif ar[i][0] != 0: arg_str = mlp.doprint(ar[i][0]) if isinstance(ar[i][0], Add): arg_str = '(%s)' % arg_str if arg_str.startswith('-'): arg_str = arg_str[1:] str_start = ' - ' else: str_start = ' + ' ol.append(str_start + arg_str + mlp.doprint(ar[i][1]) + r"\otimes " + mlp.doprint(ar[i][2])) outstr = ''.join(ol) if outstr.startswith(' + '): outstr = outstr[3:] elif outstr.startswith(' '): outstr = outstr[1:] return outstr def _pretty(self, printer=None): e = self class Fake(object): baseline = 0 def render(self, *args, **kwargs): ar = e.args # just to shorten things settings = printer._settings if printer else {} if printer: use_unicode = printer._use_unicode else: from sympy.printing.pretty.pretty_symbology import ( pretty_use_unicode) use_unicode = pretty_use_unicode() mpp = printer if printer else VectorPrettyPrinter(settings) if len(ar) == 0: return unicode(0) bar = u"\N{CIRCLED TIMES}" if use_unicode else "|" ol = [] # output list, to be concatenated to a string for i, v in enumerate(ar): # if the coef of the dyadic is 1, we skip the 1 if ar[i][0] == 1: ol.extend([u" + ", mpp.doprint(ar[i][1]), bar, mpp.doprint(ar[i][2])]) # if the coef of the dyadic is -1, we skip the 1 elif ar[i][0] == -1: ol.extend([u" - ", mpp.doprint(ar[i][1]), bar, mpp.doprint(ar[i][2])]) # If the coefficient of the dyadic is not 1 or -1, # we might wrap it in parentheses, for readability. elif ar[i][0] != 0: if isinstance(ar[i][0], Add): arg_str = mpp._print( ar[i][0]).parens()[0] else: arg_str = mpp.doprint(ar[i][0]) if arg_str.startswith(u"-"): arg_str = arg_str[1:] str_start = u" - " else: str_start = u" + " ol.extend([str_start, arg_str, u" ", mpp.doprint(ar[i][1]), bar, mpp.doprint(ar[i][2])]) outstr = u"".join(ol) if outstr.startswith(u" + "): outstr = outstr[3:] elif outstr.startswith(" "): outstr = outstr[1:] return outstr return Fake() def __rand__(self, other): """The inner product operator for a Vector or Dyadic, and a Dyadic This is for: Vector dot Dyadic Parameters ========== other : Vector The vector we are dotting with Examples ======== >>> from sympy.physics.vector import ReferenceFrame, dot, outer >>> N = ReferenceFrame('N') >>> d = outer(N.x, N.x) >>> dot(N.x, d) N.x """ from sympy.physics.vector.vector import Vector, _check_vector other = _check_vector(other) ol = Vector(0) for i, v in enumerate(self.args): ol += v[0] * v[2] * (v[1] & other) return ol def __rsub__(self, other): return (-1 * self) + other def __rxor__(self, other): """For a cross product in the form: Vector x Dyadic Parameters ========== other : Vector The Vector that we are crossing this Dyadic with Examples ======== >>> from sympy.physics.vector import ReferenceFrame, outer, cross >>> N = ReferenceFrame('N') >>> d = outer(N.x, N.x) >>> cross(N.y, d) - (N.z|N.x) """ from sympy.physics.vector.vector import _check_vector other = _check_vector(other) ol = Dyadic(0) for i, v in enumerate(self.args): ol += v[0] * ((other ^ v[1]) | v[2]) return ol def __str__(self, printer=None): """Printing method. """ ar = self.args # just to shorten things if len(ar) == 0: return str(0) ol = [] # output list, to be concatenated to a string for i, v in enumerate(ar): # if the coef of the dyadic is 1, we skip the 1 if ar[i][0] == 1: ol.append(' + (' + str(ar[i][1]) + '|' + str(ar[i][2]) + ')') # if the coef of the dyadic is -1, we skip the 1 elif ar[i][0] == -1: ol.append(' - (' + str(ar[i][1]) + '|' + str(ar[i][2]) + ')') # If the coefficient of the dyadic is not 1 or -1, # we might wrap it in parentheses, for readability. elif ar[i][0] != 0: arg_str = VectorStrPrinter().doprint(ar[i][0]) if isinstance(ar[i][0], Add): arg_str = "(%s)" % arg_str if arg_str[0] == '-': arg_str = arg_str[1:] str_start = ' - ' else: str_start = ' + ' ol.append(str_start + arg_str + '*(' + str(ar[i][1]) + '|' + str(ar[i][2]) + ')') outstr = ''.join(ol) if outstr.startswith(' + '): outstr = outstr[3:] elif outstr.startswith(' '): outstr = outstr[1:] return outstr def __sub__(self, other): """The subtraction operator. """ return self.__add__(other * -1) def __xor__(self, other): """For a cross product in the form: Dyadic x Vector. Parameters ========== other : Vector The Vector that we are crossing this Dyadic with Examples ======== >>> from sympy.physics.vector import ReferenceFrame, outer, cross >>> N = ReferenceFrame('N') >>> d = outer(N.x, N.x) >>> cross(d, N.y) (N.x|N.z) """ from sympy.physics.vector.vector import _check_vector other = _check_vector(other) ol = Dyadic(0) for i, v in enumerate(self.args): ol += v[0] * (v[1] | (v[2] ^ other)) return ol # We don't define _repr_png_ here because it would add a large amount of # data to any notebook containing SymPy expressions, without adding # anything useful to the notebook. It can still enabled manually, e.g., # for the qtconsole, with init_printing(). def _repr_latex_(self): """ IPython/Jupyter LaTeX printing To change the behavior of this (e.g., pass in some settings to LaTeX), use init_printing(). init_printing() will also enable LaTeX printing for built in numeric types like ints and container types that contain SymPy objects, like lists and dictionaries of expressions. """ from sympy.printing.latex import latex s = latex(self, mode='plain') return "$\\displaystyle %s$" % s _repr_latex_orig = _repr_latex_ _sympystr = __str__ _sympyrepr = _sympystr __repr__ = __str__ __radd__ = __add__ __rmul__ = __mul__ def express(self, frame1, frame2=None): """Expresses this Dyadic in alternate frame(s) The first frame is the list side expression, the second frame is the right side; if Dyadic is in form A.x|B.y, you can express it in two different frames. If no second frame is given, the Dyadic is expressed in only one frame. Calls the global express function Parameters ========== frame1 : ReferenceFrame The frame to express the left side of the Dyadic in frame2 : ReferenceFrame If provided, the frame to express the right side of the Dyadic in Examples ======== >>> from sympy.physics.vector import ReferenceFrame, outer, dynamicsymbols >>> N = ReferenceFrame('N') >>> q = dynamicsymbols('q') >>> B = N.orientnew('B', 'Axis', [q, N.z]) >>> d = outer(N.x, N.x) >>> d.express(B, N) cos(q)*(B.x|N.x) - sin(q)*(B.y|N.x) """ from sympy.physics.vector.functions import express return express(self, frame1, frame2) def to_matrix(self, reference_frame, second_reference_frame=None): """Returns the matrix form of the dyadic with respect to one or two reference frames. Parameters ---------- reference_frame : ReferenceFrame The reference frame that the rows and columns of the matrix correspond to. If a second reference frame is provided, this only corresponds to the rows of the matrix. second_reference_frame : ReferenceFrame, optional, default=None The reference frame that the columns of the matrix correspond to. Returns ------- matrix : ImmutableMatrix, shape(3,3) The matrix that gives the 2D tensor form. Examples ======== >>> from sympy import symbols >>> from sympy.physics.vector import ReferenceFrame, Vector >>> Vector.simp = True >>> from sympy.physics.mechanics import inertia >>> Ixx, Iyy, Izz, Ixy, Iyz, Ixz = symbols('Ixx, Iyy, Izz, Ixy, Iyz, Ixz') >>> N = ReferenceFrame('N') >>> inertia_dyadic = inertia(N, Ixx, Iyy, Izz, Ixy, Iyz, Ixz) >>> inertia_dyadic.to_matrix(N) Matrix([ [Ixx, Ixy, Ixz], [Ixy, Iyy, Iyz], [Ixz, Iyz, Izz]]) >>> beta = symbols('beta') >>> A = N.orientnew('A', 'Axis', (beta, N.x)) >>> inertia_dyadic.to_matrix(A) Matrix([ [ Ixx, Ixy*cos(beta) + Ixz*sin(beta), -Ixy*sin(beta) + Ixz*cos(beta)], [ Ixy*cos(beta) + Ixz*sin(beta), Iyy*cos(2*beta)/2 + Iyy/2 + Iyz*sin(2*beta) - Izz*cos(2*beta)/2 + Izz/2, -Iyy*sin(2*beta)/2 + Iyz*cos(2*beta) + Izz*sin(2*beta)/2], [-Ixy*sin(beta) + Ixz*cos(beta), -Iyy*sin(2*beta)/2 + Iyz*cos(2*beta) + Izz*sin(2*beta)/2, -Iyy*cos(2*beta)/2 + Iyy/2 - Iyz*sin(2*beta) + Izz*cos(2*beta)/2 + Izz/2]]) """ if second_reference_frame is None: second_reference_frame = reference_frame return Matrix([i.dot(self).dot(j) for i in reference_frame for j in second_reference_frame]).reshape(3, 3) def doit(self, **hints): """Calls .doit() on each term in the Dyadic""" return sum([Dyadic([(v[0].doit(**hints), v[1], v[2])]) for v in self.args], Dyadic(0)) def dt(self, frame): """Take the time derivative of this Dyadic in a frame. This function calls the global time_derivative method Parameters ========== frame : ReferenceFrame The frame to take the time derivative in Examples ======== >>> from sympy.physics.vector import ReferenceFrame, outer, dynamicsymbols >>> N = ReferenceFrame('N') >>> q = dynamicsymbols('q') >>> B = N.orientnew('B', 'Axis', [q, N.z]) >>> d = outer(N.x, N.x) >>> d.dt(B) - q'*(N.y|N.x) - q'*(N.x|N.y) """ from sympy.physics.vector.functions import time_derivative return time_derivative(self, frame) def simplify(self): """Returns a simplified Dyadic.""" out = Dyadic(0) for v in self.args: out += Dyadic([(v[0].simplify(), v[1], v[2])]) return out def subs(self, *args, **kwargs): """Substitution on the Dyadic. Examples ======== >>> from sympy.physics.vector import ReferenceFrame >>> from sympy import Symbol >>> N = ReferenceFrame('N') >>> s = Symbol('s') >>> a = s * (N.x|N.x) >>> a.subs({s: 2}) 2*(N.x|N.x) """ return sum([Dyadic([(v[0].subs(*args, **kwargs), v[1], v[2])]) for v in self.args], Dyadic(0)) def applyfunc(self, f): """Apply a function to each component of a Dyadic.""" if not callable(f): raise TypeError("`f` must be callable.") out = Dyadic(0) for a, b, c in self.args: out += f(a) * (b|c) return out dot = __and__ cross = __xor__ def _check_dyadic(other): if not isinstance(other, Dyadic): raise TypeError('A Dyadic must be supplied') return other

95f7547c5cfc034cd0cde374437f5f538c4a6a952928f366c9b36bf59f0500b4

""" This module can be used to solve 2D beam bending problems with singularity functions in mechanics. """ from __future__ import print_function, division from sympy.core import S, Symbol, diff, symbols from sympy.solvers import linsolve from sympy.printing import sstr from sympy.functions import SingularityFunction, Piecewise, factorial from sympy.core import sympify from sympy.integrals import integrate from sympy.series import limit from sympy.plotting import plot from sympy.external import import_module from sympy.utilities.decorator import doctest_depends_on from sympy import lambdify matplotlib = import_module('matplotlib', __import__kwargs={'fromlist':['pyplot']}) numpy = import_module('numpy', __import__kwargs={'fromlist':['linspace']}) __doctest_requires__ = {('Beam.plot_loading_results',): ['matplotlib']} class Beam(object): """ A Beam is a structural element that is capable of withstanding load primarily by resisting against bending. Beams are characterized by their cross sectional profile(Second moment of area), their length and their material. .. note:: While solving a beam bending problem, a user should choose its own sign convention and should stick to it. The results will automatically follow the chosen sign convention. Examples ======== There is a beam of length 4 meters. A constant distributed load of 6 N/m is applied from half of the beam till the end. There are two simple supports below the beam, one at the starting point and another at the ending point of the beam. The deflection of the beam at the end is restricted. Using the sign convention of downwards forces being positive. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols, Piecewise >>> E, I = symbols('E, I') >>> R1, R2 = symbols('R1, R2') >>> b = Beam(4, E, I) >>> b.apply_load(R1, 0, -1) >>> b.apply_load(6, 2, 0) >>> b.apply_load(R2, 4, -1) >>> b.bc_deflection = [(0, 0), (4, 0)] >>> b.boundary_conditions {'deflection': [(0, 0), (4, 0)], 'slope': []} >>> b.load R1*SingularityFunction(x, 0, -1) + R2*SingularityFunction(x, 4, -1) + 6*SingularityFunction(x, 2, 0) >>> b.solve_for_reaction_loads(R1, R2) >>> b.load -3*SingularityFunction(x, 0, -1) + 6*SingularityFunction(x, 2, 0) - 9*SingularityFunction(x, 4, -1) >>> b.shear_force() -3*SingularityFunction(x, 0, 0) + 6*SingularityFunction(x, 2, 1) - 9*SingularityFunction(x, 4, 0) >>> b.bending_moment() -3*SingularityFunction(x, 0, 1) + 3*SingularityFunction(x, 2, 2) - 9*SingularityFunction(x, 4, 1) >>> b.slope() (-3*SingularityFunction(x, 0, 2)/2 + SingularityFunction(x, 2, 3) - 9*SingularityFunction(x, 4, 2)/2 + 7)/(E*I) >>> b.deflection() (7*x - SingularityFunction(x, 0, 3)/2 + SingularityFunction(x, 2, 4)/4 - 3*SingularityFunction(x, 4, 3)/2)/(E*I) >>> b.deflection().rewrite(Piecewise) (7*x - Piecewise((x**3, x > 0), (0, True))/2 - 3*Piecewise(((x - 4)**3, x - 4 > 0), (0, True))/2 + Piecewise(((x - 2)**4, x - 2 > 0), (0, True))/4)/(E*I) """ def __init__(self, length, elastic_modulus, second_moment, variable=Symbol('x'), base_char='C'): """Initializes the class. Parameters ========== length : Sympifyable A Symbol or value representing the Beam's length. elastic_modulus : Sympifyable A SymPy expression representing the Beam's Modulus of Elasticity. It is a measure of the stiffness of the Beam material. It can also be a continuous function of position along the beam. second_moment : Sympifyable A SymPy expression representing the Beam's Second moment of area. It is a geometrical property of an area which reflects how its points are distributed with respect to its neutral axis. It can also be a continuous function of position along the beam. variable : Symbol, optional A Symbol object that will be used as the variable along the beam while representing the load, shear, moment, slope and deflection curve. By default, it is set to ``Symbol('x')``. base_char : String, optional A String that will be used as base character to generate sequential symbols for integration constants in cases where boundary conditions are not sufficient to solve them. """ self.length = length self.elastic_modulus = elastic_modulus self.second_moment = second_moment self.variable = variable self._base_char = base_char self._boundary_conditions = {'deflection': [], 'slope': []} self._load = 0 self._applied_loads = [] self._reaction_loads = {} self._composite_type = None self._hinge_position = None def __str__(self): str_sol = 'Beam({}, {}, {})'.format(sstr(self._length), sstr(self._elastic_modulus), sstr(self._second_moment)) return str_sol @property def reaction_loads(self): """ Returns the reaction forces in a dictionary.""" return self._reaction_loads @property def length(self): """Length of the Beam.""" return self._length @length.setter def length(self, l): self._length = sympify(l) @property def variable(self): """ A symbol that can be used as a variable along the length of the beam while representing load distribution, shear force curve, bending moment, slope curve and the deflection curve. By default, it is set to ``Symbol('x')``, but this property is mutable. Examples ======== >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> E, I = symbols('E, I') >>> x, y, z = symbols('x, y, z') >>> b = Beam(4, E, I) >>> b.variable x >>> b.variable = y >>> b.variable y >>> b = Beam(4, E, I, z) >>> b.variable z """ return self._variable @variable.setter def variable(self, v): if isinstance(v, Symbol): self._variable = v else: raise TypeError("""The variable should be a Symbol object.""") @property def elastic_modulus(self): """Young's Modulus of the Beam. """ return self._elastic_modulus @elastic_modulus.setter def elastic_modulus(self, e): self._elastic_modulus = sympify(e) @property def second_moment(self): """Second moment of area of the Beam. """ return self._second_moment @second_moment.setter def second_moment(self, i): self._second_moment = sympify(i) @property def boundary_conditions(self): """ Returns a dictionary of boundary conditions applied on the beam. The dictionary has three kewwords namely moment, slope and deflection. The value of each keyword is a list of tuple, where each tuple contains loaction and value of a boundary condition in the format (location, value). Examples ======== There is a beam of length 4 meters. The bending moment at 0 should be 4 and at 4 it should be 0. The slope of the beam should be 1 at 0. The deflection should be 2 at 0. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> E, I = symbols('E, I') >>> b = Beam(4, E, I) >>> b.bc_deflection = [(0, 2)] >>> b.bc_slope = [(0, 1)] >>> b.boundary_conditions {'deflection': [(0, 2)], 'slope': [(0, 1)]} Here the deflection of the beam should be ``2`` at ``0``. Similarly, the slope of the beam should be ``1`` at ``0``. """ return self._boundary_conditions @property def bc_slope(self): return self._boundary_conditions['slope'] @bc_slope.setter def bc_slope(self, s_bcs): self._boundary_conditions['slope'] = s_bcs @property def bc_deflection(self): return self._boundary_conditions['deflection'] @bc_deflection.setter def bc_deflection(self, d_bcs): self._boundary_conditions['deflection'] = d_bcs def join(self, beam, via="fixed"): """ This method joins two beams to make a new composite beam system. Passed Beam class instance is attached to the right end of calling object. This method can be used to form beams having Discontinuous values of Elastic modulus or Second moment. Parameters ========== beam : Beam class object The Beam object which would be connected to the right of calling object. via : String States the way two Beam object would get connected - For axially fixed Beams, via="fixed" - For Beams connected via hinge, via="hinge" Examples ======== There is a cantilever beam of length 4 meters. For first 2 meters its moment of inertia is `1.5*I` and `I` for the other end. A pointload of magnitude 4 N is applied from the top at its free end. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> E, I = symbols('E, I') >>> R1, R2 = symbols('R1, R2') >>> b1 = Beam(2, E, 1.5*I) >>> b2 = Beam(2, E, I) >>> b = b1.join(b2, "fixed") >>> b.apply_load(20, 4, -1) >>> b.apply_load(R1, 0, -1) >>> b.apply_load(R2, 0, -2) >>> b.bc_slope = [(0, 0)] >>> b.bc_deflection = [(0, 0)] >>> b.solve_for_reaction_loads(R1, R2) >>> b.load 80*SingularityFunction(x, 0, -2) - 20*SingularityFunction(x, 0, -1) + 20*SingularityFunction(x, 4, -1) >>> b.slope() (((80*SingularityFunction(x, 0, 1) - 10*SingularityFunction(x, 0, 2) + 10*SingularityFunction(x, 4, 2))/I - 120/I)/E + 80.0/(E*I))*SingularityFunction(x, 2, 0) + 0.666666666666667*(80*SingularityFunction(x, 0, 1) - 10*SingularityFunction(x, 0, 2) + 10*SingularityFunction(x, 4, 2))*SingularityFunction(x, 0, 0)/(E*I) - 0.666666666666667*(80*SingularityFunction(x, 0, 1) - 10*SingularityFunction(x, 0, 2) + 10*SingularityFunction(x, 4, 2))*SingularityFunction(x, 2, 0)/(E*I) """ x = self.variable E = self.elastic_modulus new_length = self.length + beam.length if self.second_moment != beam.second_moment: new_second_moment = Piecewise((self.second_moment, x<=self.length), (beam.second_moment, x<=new_length)) else: new_second_moment = self.second_moment if via == "fixed": new_beam = Beam(new_length, E, new_second_moment, x) new_beam._composite_type = "fixed" return new_beam if via == "hinge": new_beam = Beam(new_length, E, new_second_moment, x) new_beam._composite_type = "hinge" new_beam._hinge_position = self.length return new_beam def apply_support(self, loc, type="fixed"): """ This method applies support to a particular beam object. Parameters ========== loc : Sympifyable Location of point at which support is applied. type : String Determines type of Beam support applied. To apply support structure with - zero degree of freedom, type = "fixed" - one degree of freedom, type = "pin" - two degrees of freedom, type = "roller" Examples ======== There is a beam of length 30 meters. A moment of magnitude 120 Nm is applied in the clockwise direction at the end of the beam. A pointload of magnitude 8 N is applied from the top of the beam at the starting point. There are two simple supports below the beam. One at the end and another one at a distance of 10 meters from the start. The deflection is restricted at both the supports. Using the sign convention of upward forces and clockwise moment being positive. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> E, I = symbols('E, I') >>> b = Beam(30, E, I) >>> b.apply_support(10, 'roller') >>> b.apply_support(30, 'roller') >>> b.apply_load(-8, 0, -1) >>> b.apply_load(120, 30, -2) >>> R_10, R_30 = symbols('R_10, R_30') >>> b.solve_for_reaction_loads(R_10, R_30) >>> b.load -8*SingularityFunction(x, 0, -1) + 6*SingularityFunction(x, 10, -1) + 120*SingularityFunction(x, 30, -2) + 2*SingularityFunction(x, 30, -1) >>> b.slope() (-4*SingularityFunction(x, 0, 2) + 3*SingularityFunction(x, 10, 2) + 120*SingularityFunction(x, 30, 1) + SingularityFunction(x, 30, 2) + 4000/3)/(E*I) """ if type == "pin" or type == "roller": reaction_load = Symbol('R_'+str(loc)) self.apply_load(reaction_load, loc, -1) self.bc_deflection.append((loc, 0)) else: reaction_load = Symbol('R_'+str(loc)) reaction_moment = Symbol('M_'+str(loc)) self.apply_load(reaction_load, loc, -1) self.apply_load(reaction_moment, loc, -2) self.bc_deflection.append((loc, 0)) self.bc_slope.append((loc, 0)) def apply_load(self, value, start, order, end=None): """ This method adds up the loads given to a particular beam object. Parameters ========== value : Sympifyable The magnitude of an applied load. start : Sympifyable The starting point of the applied load. For point moments and point forces this is the location of application. order : Integer The order of the applied load. - For moments, order = -2 - For point loads, order =-1 - For constant distributed load, order = 0 - For ramp loads, order = 1 - For parabolic ramp loads, order = 2 - ... so on. end : Sympifyable, optional An optional argument that can be used if the load has an end point within the length of the beam. Examples ======== There is a beam of length 4 meters. A moment of magnitude 3 Nm is applied in the clockwise direction at the starting point of the beam. A point load of magnitude 4 N is applied from the top of the beam at 2 meters from the starting point and a parabolic ramp load of magnitude 2 N/m is applied below the beam starting from 2 meters to 3 meters away from the starting point of the beam. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> E, I = symbols('E, I') >>> b = Beam(4, E, I) >>> b.apply_load(-3, 0, -2) >>> b.apply_load(4, 2, -1) >>> b.apply_load(-2, 2, 2, end=3) >>> b.load -3*SingularityFunction(x, 0, -2) + 4*SingularityFunction(x, 2, -1) - 2*SingularityFunction(x, 2, 2) + 2*SingularityFunction(x, 3, 0) + 4*SingularityFunction(x, 3, 1) + 2*SingularityFunction(x, 3, 2) """ x = self.variable value = sympify(value) start = sympify(start) order = sympify(order) self._applied_loads.append((value, start, order, end)) self._load += value*SingularityFunction(x, start, order) if end: if order.is_negative: msg = ("If 'end' is provided the 'order' of the load cannot " "be negative, i.e. 'end' is only valid for distributed " "loads.") raise ValueError(msg) # NOTE : A Taylor series can be used to define the summation of # singularity functions that subtract from the load past the end # point such that it evaluates to zero past 'end'. f = value * x**order for i in range(0, order + 1): self._load -= (f.diff(x, i).subs(x, end - start) * SingularityFunction(x, end, i) / factorial(i)) def remove_load(self, value, start, order, end=None): """ This method removes a particular load present on the beam object. Returns a ValueError if the load passed as an argument is not present on the beam. Parameters ========== value : Sympifyable The magnitude of an applied load. start : Sympifyable The starting point of the applied load. For point moments and point forces this is the location of application. order : Integer The order of the applied load. - For moments, order= -2 - For point loads, order=-1 - For constant distributed load, order=0 - For ramp loads, order=1 - For parabolic ramp loads, order=2 - ... so on. end : Sympifyable, optional An optional argument that can be used if the load has an end point within the length of the beam. Examples ======== There is a beam of length 4 meters. A moment of magnitude 3 Nm is applied in the clockwise direction at the starting point of the beam. A pointload of magnitude 4 N is applied from the top of the beam at 2 meters from the starting point and a parabolic ramp load of magnitude 2 N/m is applied below the beam starting from 2 meters to 3 meters away from the starting point of the beam. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> E, I = symbols('E, I') >>> b = Beam(4, E, I) >>> b.apply_load(-3, 0, -2) >>> b.apply_load(4, 2, -1) >>> b.apply_load(-2, 2, 2, end=3) >>> b.load -3*SingularityFunction(x, 0, -2) + 4*SingularityFunction(x, 2, -1) - 2*SingularityFunction(x, 2, 2) + 2*SingularityFunction(x, 3, 0) + 4*SingularityFunction(x, 3, 1) + 2*SingularityFunction(x, 3, 2) >>> b.remove_load(-2, 2, 2, end = 3) >>> b.load -3*SingularityFunction(x, 0, -2) + 4*SingularityFunction(x, 2, -1) """ x = self.variable value = sympify(value) start = sympify(start) order = sympify(order) if (value, start, order, end) in self._applied_loads: self._load -= value*SingularityFunction(x, start, order) self._applied_loads.remove((value, start, order, end)) else: msg = "No such load distribution exists on the beam object." raise ValueError(msg) if end: # TODO : This is essentially duplicate code wrt to apply_load, # would be better to move it to one location and both methods use # it. if order.is_negative: msg = ("If 'end' is provided the 'order' of the load cannot " "be negative, i.e. 'end' is only valid for distributed " "loads.") raise ValueError(msg) # NOTE : A Taylor series can be used to define the summation of # singularity functions that subtract from the load past the end # point such that it evaluates to zero past 'end'. f = value * x**order for i in range(0, order + 1): self._load += (f.diff(x, i).subs(x, end - start) * SingularityFunction(x, end, i) / factorial(i)) @property def load(self): """ Returns a Singularity Function expression which represents the load distribution curve of the Beam object. Examples ======== There is a beam of length 4 meters. A moment of magnitude 3 Nm is applied in the clockwise direction at the starting point of the beam. A point load of magnitude 4 N is applied from the top of the beam at 2 meters from the starting point and a parabolic ramp load of magnitude 2 N/m is applied below the beam starting from 3 meters away from the starting point of the beam. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> E, I = symbols('E, I') >>> b = Beam(4, E, I) >>> b.apply_load(-3, 0, -2) >>> b.apply_load(4, 2, -1) >>> b.apply_load(-2, 3, 2) >>> b.load -3*SingularityFunction(x, 0, -2) + 4*SingularityFunction(x, 2, -1) - 2*SingularityFunction(x, 3, 2) """ return self._load @property def applied_loads(self): """ Returns a list of all loads applied on the beam object. Each load in the list is a tuple of form (value, start, order, end). Examples ======== There is a beam of length 4 meters. A moment of magnitude 3 Nm is applied in the clockwise direction at the starting point of the beam. A pointload of magnitude 4 N is applied from the top of the beam at 2 meters from the starting point. Another pointload of magnitude 5 N is applied at same position. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> E, I = symbols('E, I') >>> b = Beam(4, E, I) >>> b.apply_load(-3, 0, -2) >>> b.apply_load(4, 2, -1) >>> b.apply_load(5, 2, -1) >>> b.load -3*SingularityFunction(x, 0, -2) + 9*SingularityFunction(x, 2, -1) >>> b.applied_loads [(-3, 0, -2, None), (4, 2, -1, None), (5, 2, -1, None)] """ return self._applied_loads def _solve_hinge_beams(self, *reactions): """Method to find integration constants and reactional variables in a composite beam connected via hinge. This method resolves the composite Beam into its sub-beams and then equations of shear force, bending moment, slope and deflection are evaluated for both of them separately. These equations are then solved for unknown reactions and integration constants using the boundary conditions applied on the Beam. Equal deflection of both sub-beams at the hinge joint gives us another equation to solve the system. Examples ======== A combined beam, with constant fkexural rigidity E*I, is formed by joining a Beam of length 2*l to the right of another Beam of length l. The whole beam is fixed at both of its both end. A point load of magnitude P is also applied from the top at a distance of 2*l from starting point. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> E, I = symbols('E, I') >>> l=symbols('l', positive=True) >>> b1=Beam(l ,E,I) >>> b2=Beam(2*l ,E,I) >>> b=b1.join(b2,"hinge") >>> M1, A1, M2, A2, P = symbols('M1 A1 M2 A2 P') >>> b.apply_load(A1,0,-1) >>> b.apply_load(M1,0,-2) >>> b.apply_load(P,2*l,-1) >>> b.apply_load(A2,3*l,-1) >>> b.apply_load(M2,3*l,-2) >>> b.bc_slope=[(0,0), (3*l, 0)] >>> b.bc_deflection=[(0,0), (3*l, 0)] >>> b.solve_for_reaction_loads(M1, A1, M2, A2) >>> b.reaction_loads {A1: -5*P/18, A2: -13*P/18, M1: 5*P*l/18, M2: -4*P*l/9} >>> b.slope() (5*P*l*SingularityFunction(x, 0, 1)/18 - 5*P*SingularityFunction(x, 0, 2)/36 + 5*P*SingularityFunction(x, l, 2)/36)*SingularityFunction(x, 0, 0)/(E*I) - (5*P*l*SingularityFunction(x, 0, 1)/18 - 5*P*SingularityFunction(x, 0, 2)/36 + 5*P*SingularityFunction(x, l, 2)/36)*SingularityFunction(x, l, 0)/(E*I) + (P*l**2/18 - 4*P*l*SingularityFunction(-l + x, 2*l, 1)/9 - 5*P*SingularityFunction(-l + x, 0, 2)/36 + P*SingularityFunction(-l + x, l, 2)/2 - 13*P*SingularityFunction(-l + x, 2*l, 2)/36)*SingularityFunction(x, l, 0)/(E*I) >>> b.deflection() (5*P*l*SingularityFunction(x, 0, 2)/36 - 5*P*SingularityFunction(x, 0, 3)/108 + 5*P*SingularityFunction(x, l, 3)/108)*SingularityFunction(x, 0, 0)/(E*I) - (5*P*l*SingularityFunction(x, 0, 2)/36 - 5*P*SingularityFunction(x, 0, 3)/108 + 5*P*SingularityFunction(x, l, 3)/108)*SingularityFunction(x, l, 0)/(E*I) + (5*P*l**3/54 + P*l**2*(-l + x)/18 - 2*P*l*SingularityFunction(-l + x, 2*l, 2)/9 - 5*P*SingularityFunction(-l + x, 0, 3)/108 + P*SingularityFunction(-l + x, l, 3)/6 - 13*P*SingularityFunction(-l + x, 2*l, 3)/108)*SingularityFunction(x, l, 0)/(E*I) """ x = self.variable l = self._hinge_position E = self._elastic_modulus I = self._second_moment if isinstance(I, Piecewise): I1 = I.args[0][0] I2 = I.args[1][0] else: I1 = I2 = I load_1 = 0 # Load equation on first segment of composite beam load_2 = 0 # Load equation on second segment of composite beam # Distributing load on both segments for load in self.applied_loads: if load[1] < l: load_1 += load[0]*SingularityFunction(x, load[1], load[2]) if load[2] == 0: load_1 -= load[0]*SingularityFunction(x, load[3], load[2]) elif load[2] > 0: load_1 -= load[0]*SingularityFunction(x, load[3], load[2]) + load[0]*SingularityFunction(x, load[3], 0) elif load[1] == l: load_1 += load[0]*SingularityFunction(x, load[1], load[2]) load_2 += load[0]*SingularityFunction(x, load[1] - l, load[2]) elif load[1] > l: load_2 += load[0]*SingularityFunction(x, load[1] - l, load[2]) if load[2] == 0: load_2 -= load[0]*SingularityFunction(x, load[3] - l, load[2]) elif load[2] > 0: load_2 -= load[0]*SingularityFunction(x, load[3] - l, load[2]) + load[0]*SingularityFunction(x, load[3] - l, 0) h = Symbol('h') # Force due to hinge load_1 += h*SingularityFunction(x, l, -1) load_2 -= h*SingularityFunction(x, 0, -1) eq = [] shear_1 = integrate(load_1, x) shear_curve_1 = limit(shear_1, x, l) eq.append(shear_curve_1) bending_1 = integrate(shear_1, x) moment_curve_1 = limit(bending_1, x, l) eq.append(moment_curve_1) shear_2 = integrate(load_2, x) shear_curve_2 = limit(shear_2, x, self.length - l) eq.append(shear_curve_2) bending_2 = integrate(shear_2, x) moment_curve_2 = limit(bending_2, x, self.length - l) eq.append(moment_curve_2) C1 = Symbol('C1') C2 = Symbol('C2') C3 = Symbol('C3') C4 = Symbol('C4') slope_1 = S(1)/(E*I1)*(integrate(bending_1, x) + C1) def_1 = S(1)/(E*I1)*(integrate((E*I)*slope_1, x) + C1*x + C2) slope_2 = S(1)/(E*I2)*(integrate(integrate(integrate(load_2, x), x), x) + C3) def_2 = S(1)/(E*I2)*(integrate((E*I)*slope_2, x) + C4) for position, value in self.bc_slope: if position<l: eq.append(slope_1.subs(x, position) - value) else: eq.append(slope_2.subs(x, position - l) - value) for position, value in self.bc_deflection: if position<l: eq.append(def_1.subs(x, position) - value) else: eq.append(def_2.subs(x, position - l) - value) eq.append(def_1.subs(x, l) - def_2.subs(x, 0)) # Deflection of both the segments at hinge would be equal constants = list(linsolve(eq, C1, C2, C3, C4, h, *reactions)) reaction_values = list(constants[0])[5:] self._reaction_loads = dict(zip(reactions, reaction_values)) self._load = self._load.subs(self._reaction_loads) # Substituting constants and reactional load and moments with their corresponding values slope_1 = slope_1.subs({C1: constants[0][0], h:constants[0][4]}).subs(self._reaction_loads) def_1 = def_1.subs({C1: constants[0][0], C2: constants[0][1], h:constants[0][4]}).subs(self._reaction_loads) slope_2 = slope_2.subs({x: x-l, C3: constants[0][2], h:constants[0][4]}).subs(self._reaction_loads) def_2 = def_2.subs({x: x-l,C3: constants[0][2], C4: constants[0][3], h:constants[0][4]}).subs(self._reaction_loads) self._hinge_beam_slope = slope_1*SingularityFunction(x, 0, 0) - slope_1*SingularityFunction(x, l, 0) + slope_2*SingularityFunction(x, l, 0) self._hinge_beam_deflection = def_1*SingularityFunction(x, 0, 0) - def_1*SingularityFunction(x, l, 0) + def_2*SingularityFunction(x, l, 0) def solve_for_reaction_loads(self, *reactions): """ Solves for the reaction forces. Examples ======== There is a beam of length 30 meters. A moment of magnitude 120 Nm is applied in the clockwise direction at the end of the beam. A pointload of magnitude 8 N is applied from the top of the beam at the starting point. There are two simple supports below the beam. One at the end and another one at a distance of 10 meters from the start. The deflection is restricted at both the supports. Using the sign convention of upward forces and clockwise moment being positive. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols, linsolve, limit >>> E, I = symbols('E, I') >>> R1, R2 = symbols('R1, R2') >>> b = Beam(30, E, I) >>> b.apply_load(-8, 0, -1) >>> b.apply_load(R1, 10, -1) # Reaction force at x = 10 >>> b.apply_load(R2, 30, -1) # Reaction force at x = 30 >>> b.apply_load(120, 30, -2) >>> b.bc_deflection = [(10, 0), (30, 0)] >>> b.load R1*SingularityFunction(x, 10, -1) + R2*SingularityFunction(x, 30, -1) - 8*SingularityFunction(x, 0, -1) + 120*SingularityFunction(x, 30, -2) >>> b.solve_for_reaction_loads(R1, R2) >>> b.reaction_loads {R1: 6, R2: 2} >>> b.load -8*SingularityFunction(x, 0, -1) + 6*SingularityFunction(x, 10, -1) + 120*SingularityFunction(x, 30, -2) + 2*SingularityFunction(x, 30, -1) """ if self._composite_type == "hinge": return self._solve_hinge_beams(*reactions) x = self.variable l = self.length C3 = Symbol('C3') C4 = Symbol('C4') shear_curve = limit(self.shear_force(), x, l) moment_curve = limit(self.bending_moment(), x, l) slope_eqs = [] deflection_eqs = [] slope_curve = integrate(self.bending_moment(), x) + C3 for position, value in self._boundary_conditions['slope']: eqs = slope_curve.subs(x, position) - value slope_eqs.append(eqs) deflection_curve = integrate(slope_curve, x) + C4 for position, value in self._boundary_conditions['deflection']: eqs = deflection_curve.subs(x, position) - value deflection_eqs.append(eqs) solution = list((linsolve([shear_curve, moment_curve] + slope_eqs + deflection_eqs, (C3, C4) + reactions).args)[0]) solution = solution[2:] self._reaction_loads = dict(zip(reactions, solution)) self._load = self._load.subs(self._reaction_loads) def shear_force(self): """ Returns a Singularity Function expression which represents the shear force curve of the Beam object. Examples ======== There is a beam of length 30 meters. A moment of magnitude 120 Nm is applied in the clockwise direction at the end of the beam. A pointload of magnitude 8 N is applied from the top of the beam at the starting point. There are two simple supports below the beam. One at the end and another one at a distance of 10 meters from the start. The deflection is restricted at both the supports. Using the sign convention of upward forces and clockwise moment being positive. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> E, I = symbols('E, I') >>> R1, R2 = symbols('R1, R2') >>> b = Beam(30, E, I) >>> b.apply_load(-8, 0, -1) >>> b.apply_load(R1, 10, -1) >>> b.apply_load(R2, 30, -1) >>> b.apply_load(120, 30, -2) >>> b.bc_deflection = [(10, 0), (30, 0)] >>> b.solve_for_reaction_loads(R1, R2) >>> b.shear_force() -8*SingularityFunction(x, 0, 0) + 6*SingularityFunction(x, 10, 0) + 120*SingularityFunction(x, 30, -1) + 2*SingularityFunction(x, 30, 0) """ x = self.variable return integrate(self.load, x) def max_shear_force(self): """Returns maximum Shear force and its coordinate in the Beam object.""" from sympy import solve, Mul, Interval shear_curve = self.shear_force() x = self.variable terms = shear_curve.args singularity = [] # Points at which shear function changes for term in terms: if isinstance(term, Mul): term = term.args[-1] # SingularityFunction in the term singularity.append(term.args[1]) singularity.sort() singularity = list(set(singularity)) intervals = [] # List of Intervals with discrete value of shear force shear_values = [] # List of values of shear force in each interval for i, s in enumerate(singularity): if s == 0: continue try: shear_slope = Piecewise((float("nan"), x<=singularity[i-1]),(self._load.rewrite(Piecewise), x<s), (float("nan"), True)) points = solve(shear_slope, x) val = [] for point in points: val.append(shear_curve.subs(x, point)) points.extend([singularity[i-1], s]) val.extend([limit(shear_curve, x, singularity[i-1], '+'), limit(shear_curve, x, s, '-')]) val = list(map(abs, val)) max_shear = max(val) shear_values.append(max_shear) intervals.append(points[val.index(max_shear)]) # If shear force in a particular Interval has zero or constant # slope, then above block gives NotImplementedError as # solve can't represent Interval solutions. except NotImplementedError: initial_shear = limit(shear_curve, x, singularity[i-1], '+') final_shear = limit(shear_curve, x, s, '-') # If shear_curve has a constant slope(it is a line). if shear_curve.subs(x, (singularity[i-1] + s)/2) == (initial_shear + final_shear)/2 and initial_shear != final_shear: shear_values.extend([initial_shear, final_shear]) intervals.extend([singularity[i-1], s]) else: # shear_curve has same value in whole Interval shear_values.append(final_shear) intervals.append(Interval(singularity[i-1], s)) shear_values = list(map(abs, shear_values)) maximum_shear = max(shear_values) point = intervals[shear_values.index(maximum_shear)] return (point, maximum_shear) def bending_moment(self): """ Returns a Singularity Function expression which represents the bending moment curve of the Beam object. Examples ======== There is a beam of length 30 meters. A moment of magnitude 120 Nm is applied in the clockwise direction at the end of the beam. A pointload of magnitude 8 N is applied from the top of the beam at the starting point. There are two simple supports below the beam. One at the end and another one at a distance of 10 meters from the start. The deflection is restricted at both the supports. Using the sign convention of upward forces and clockwise moment being positive. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> E, I = symbols('E, I') >>> R1, R2 = symbols('R1, R2') >>> b = Beam(30, E, I) >>> b.apply_load(-8, 0, -1) >>> b.apply_load(R1, 10, -1) >>> b.apply_load(R2, 30, -1) >>> b.apply_load(120, 30, -2) >>> b.bc_deflection = [(10, 0), (30, 0)] >>> b.solve_for_reaction_loads(R1, R2) >>> b.bending_moment() -8*SingularityFunction(x, 0, 1) + 6*SingularityFunction(x, 10, 1) + 120*SingularityFunction(x, 30, 0) + 2*SingularityFunction(x, 30, 1) """ x = self.variable return integrate(self.shear_force(), x) def max_bmoment(self): """Returns maximum Shear force and its coordinate in the Beam object.""" from sympy import solve, Mul, Interval bending_curve = self.bending_moment() x = self.variable terms = bending_curve.args singularity = [] # Points at which bending moment changes for term in terms: if isinstance(term, Mul): term = term.args[-1] # SingularityFunction in the term singularity.append(term.args[1]) singularity.sort() singularity = list(set(singularity)) intervals = [] # List of Intervals with discrete value of bending moment moment_values = [] # List of values of bending moment in each interval for i, s in enumerate(singularity): if s == 0: continue try: moment_slope = Piecewise((float("nan"), x<=singularity[i-1]),(self.shear_force().rewrite(Piecewise), x<s), (float("nan"), True)) points = solve(moment_slope, x) val = [] for point in points: val.append(bending_curve.subs(x, point)) points.extend([singularity[i-1], s]) val.extend([limit(bending_curve, x, singularity[i-1], '+'), limit(bending_curve, x, s, '-')]) val = list(map(abs, val)) max_moment = max(val) moment_values.append(max_moment) intervals.append(points[val.index(max_moment)]) # If bending moment in a particular Interval has zero or constant # slope, then above block gives NotImplementedError as solve # can't represent Interval solutions. except NotImplementedError: initial_moment = limit(bending_curve, x, singularity[i-1], '+') final_moment = limit(bending_curve, x, s, '-') # If bending_curve has a constant slope(it is a line). if bending_curve.subs(x, (singularity[i-1] + s)/2) == (initial_moment + final_moment)/2 and initial_moment != final_moment: moment_values.extend([initial_moment, final_moment]) intervals.extend([singularity[i-1], s]) else: # bending_curve has same value in whole Interval moment_values.append(final_moment) intervals.append(Interval(singularity[i-1], s)) moment_values = list(map(abs, moment_values)) maximum_moment = max(moment_values) point = intervals[moment_values.index(maximum_moment)] return (point, maximum_moment) def point_cflexure(self): """ Returns a Set of point(s) with zero bending moment and where bending moment curve of the beam object changes its sign from negative to positive or vice versa. Examples ======== There is is 10 meter long overhanging beam. There are two simple supports below the beam. One at the start and another one at a distance of 6 meters from the start. Point loads of magnitude 10KN and 20KN are applied at 2 meters and 4 meters from start respectively. A Uniformly distribute load of magnitude of magnitude 3KN/m is also applied on top starting from 6 meters away from starting point till end. Using the sign convention of upward forces and clockwise moment being positive. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> E, I = symbols('E, I') >>> b = Beam(10, E, I) >>> b.apply_load(-4, 0, -1) >>> b.apply_load(-46, 6, -1) >>> b.apply_load(10, 2, -1) >>> b.apply_load(20, 4, -1) >>> b.apply_load(3, 6, 0) >>> b.point_cflexure() [10/3] """ from sympy import solve, Piecewise # To restrict the range within length of the Beam moment_curve = Piecewise((float("nan"), self.variable<=0), (self.bending_moment(), self.variable<self.length), (float("nan"), True)) points = solve(moment_curve.rewrite(Piecewise), self.variable, domain=S.Reals) return points def slope(self): """ Returns a Singularity Function expression which represents the slope the elastic curve of the Beam object. Examples ======== There is a beam of length 30 meters. A moment of magnitude 120 Nm is applied in the clockwise direction at the end of the beam. A pointload of magnitude 8 N is applied from the top of the beam at the starting point. There are two simple supports below the beam. One at the end and another one at a distance of 10 meters from the start. The deflection is restricted at both the supports. Using the sign convention of upward forces and clockwise moment being positive. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> E, I = symbols('E, I') >>> R1, R2 = symbols('R1, R2') >>> b = Beam(30, E, I) >>> b.apply_load(-8, 0, -1) >>> b.apply_load(R1, 10, -1) >>> b.apply_load(R2, 30, -1) >>> b.apply_load(120, 30, -2) >>> b.bc_deflection = [(10, 0), (30, 0)] >>> b.solve_for_reaction_loads(R1, R2) >>> b.slope() (-4*SingularityFunction(x, 0, 2) + 3*SingularityFunction(x, 10, 2) + 120*SingularityFunction(x, 30, 1) + SingularityFunction(x, 30, 2) + 4000/3)/(E*I) """ x = self.variable E = self.elastic_modulus I = self.second_moment if self._composite_type == "hinge": return self._hinge_beam_slope if not self._boundary_conditions['slope']: return diff(self.deflection(), x) if isinstance(I, Piecewise) and self._composite_type == "fixed": args = I.args slope = 0 conditions = [] prev_slope = 0 prev_end = 0 for i in range(len(args)): if i != 0: prev_end = args[i-1][1].args[1] slope_value = S(1)/E*integrate(self.bending_moment()/args[i][0], (x, prev_end, x)) if i != len(args) - 1: slope += (prev_slope + slope_value)*SingularityFunction(x, prev_end, 0) - \ (prev_slope + slope_value)*SingularityFunction(x, args[i][1].args[1], 0) else: slope += (prev_slope + slope_value)*SingularityFunction(x, prev_end, 0) prev_slope = slope_value.subs(x, args[i][1].args[1]) return slope C3 = Symbol('C3') slope_curve = integrate(S(1)/(E*I)*self.bending_moment(), x) + C3 bc_eqs = [] for position, value in self._boundary_conditions['slope']: eqs = slope_curve.subs(x, position) - value bc_eqs.append(eqs) constants = list(linsolve(bc_eqs, C3)) slope_curve = slope_curve.subs({C3: constants[0][0]}) return slope_curve def deflection(self): """ Returns a Singularity Function expression which represents the elastic curve or deflection of the Beam object. Examples ======== There is a beam of length 30 meters. A moment of magnitude 120 Nm is applied in the clockwise direction at the end of the beam. A pointload of magnitude 8 N is applied from the top of the beam at the starting point. There are two simple supports below the beam. One at the end and another one at a distance of 10 meters from the start. The deflection is restricted at both the supports. Using the sign convention of upward forces and clockwise moment being positive. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> E, I = symbols('E, I') >>> R1, R2 = symbols('R1, R2') >>> b = Beam(30, E, I) >>> b.apply_load(-8, 0, -1) >>> b.apply_load(R1, 10, -1) >>> b.apply_load(R2, 30, -1) >>> b.apply_load(120, 30, -2) >>> b.bc_deflection = [(10, 0), (30, 0)] >>> b.solve_for_reaction_loads(R1, R2) >>> b.deflection() (4000*x/3 - 4*SingularityFunction(x, 0, 3)/3 + SingularityFunction(x, 10, 3) + 60*SingularityFunction(x, 30, 2) + SingularityFunction(x, 30, 3)/3 - 12000)/(E*I) """ x = self.variable E = self.elastic_modulus I = self.second_moment if self._composite_type == "hinge": return self._hinge_beam_deflection if not self._boundary_conditions['deflection'] and not self._boundary_conditions['slope']: if isinstance(I, Piecewise) and self._composite_type == "fixed": args = I.args conditions = [] prev_slope = 0 prev_def = 0 prev_end = 0 deflection = 0 for i in range(len(args)): if i != 0: prev_end = args[i-1][1].args[1] slope_value = S(1)/E*integrate(self.bending_moment()/args[i][0], (x, prev_end, x)) recent_segment_slope = prev_slope + slope_value deflection_value = integrate(recent_segment_slope, (x, prev_end, x)) if i != len(args) - 1: deflection += (prev_def + deflection_value)*SingularityFunction(x, prev_end, 0) \ - (prev_def + deflection_value)*SingularityFunction(x, args[i][1].args[1], 0) else: deflection += (prev_def + deflection_value)*SingularityFunction(x, prev_end, 0) prev_slope = slope_value.subs(x, args[i][1].args[1]) prev_def = deflection_value.subs(x, args[i][1].args[1]) return deflection base_char = self._base_char constants = symbols(base_char + '3:5') return S(1)/(E*I)*integrate(integrate(self.bending_moment(), x), x) + constants[0]*x + constants[1] elif not self._boundary_conditions['deflection']: base_char = self._base_char constant = symbols(base_char + '4') return integrate(self.slope(), x) + constant elif not self._boundary_conditions['slope'] and self._boundary_conditions['deflection']: if isinstance(I, Piecewise) and self._composite_type == "fixed": args = I.args conditions = [] prev_slope = 0 prev_def = 0 prev_end = 0 deflection = 0 for i in range(len(args)): if i != 0: prev_end = args[i-1][1].args[1] slope_value = S(1)/E*integrate(self.bending_moment()/args[i][0], (x, prev_end, x)) recent_segment_slope = prev_slope + slope_value deflection_value = integrate(recent_segment_slope, (x, prev_end, x)) if i != len(args) - 1: deflection += (prev_def + deflection_value)*SingularityFunction(x, prev_end, 0) \ - (prev_def + deflection_value)*SingularityFunction(x, args[i][1].args[1], 0) else: deflection += (prev_def + deflection_value)*SingularityFunction(x, prev_end, 0) prev_slope = slope_value.subs(x, args[i][1].args[1]) prev_def = deflection_value.subs(x, args[i][1].args[1]) return deflection base_char = self._base_char C3, C4 = symbols(base_char + '3:5') # Integration constants slope_curve = integrate(self.bending_moment(), x) + C3 deflection_curve = integrate(slope_curve, x) + C4 bc_eqs = [] for position, value in self._boundary_conditions['deflection']: eqs = deflection_curve.subs(x, position) - value bc_eqs.append(eqs) constants = list(linsolve(bc_eqs, (C3, C4))) deflection_curve = deflection_curve.subs({C3: constants[0][0], C4: constants[0][1]}) return S(1)/(E*I)*deflection_curve if isinstance(I, Piecewise) and self._composite_type == "fixed": args = I.args conditions = [] prev_slope = 0 prev_def = 0 prev_end = 0 deflection = 0 for i in range(len(args)): if i != 0: prev_end = args[i-1][1].args[1] slope_value = S(1)/E*integrate(self.bending_moment()/args[i][0], (x, prev_end, x)) recent_segment_slope = prev_slope + slope_value deflection_value = integrate(recent_segment_slope, (x, prev_end, x)) if i != len(args) - 1: deflection += (prev_def + deflection_value)*SingularityFunction(x, prev_end, 0) \ - (prev_def + deflection_value)*SingularityFunction(x, args[i][1].args[1], 0) else: deflection += (prev_def + deflection_value)*SingularityFunction(x, prev_end, 0) prev_slope = slope_value.subs(x, args[i][1].args[1]) prev_def = deflection_value.subs(x, args[i][1].args[1]) return deflection C4 = Symbol('C4') deflection_curve = integrate(self.slope(), x) + C4 bc_eqs = [] for position, value in self._boundary_conditions['deflection']: eqs = deflection_curve.subs(x, position) - value bc_eqs.append(eqs) constants = list(linsolve(bc_eqs, C4)) deflection_curve = deflection_curve.subs({C4: constants[0][0]}) return deflection_curve def max_deflection(self): """ Returns point of max deflection and its coresponding deflection value in a Beam object. """ from sympy import solve, Piecewise # To restrict the range within length of the Beam slope_curve = Piecewise((float("nan"), self.variable<=0), (self.slope(), self.variable<self.length), (float("nan"), True)) points = solve(slope_curve.rewrite(Piecewise), self.variable, domain=S.Reals) deflection_curve = self.deflection() deflections = [deflection_curve.subs(self.variable, x) for x in points] deflections = list(map(abs, deflections)) if len(deflections) != 0: max_def = max(deflections) return (points[deflections.index(max_def)], max_def) else: return None def plot_shear_force(self, subs=None): """ Returns a plot for Shear force present in the Beam object. Parameters ========== subs : dictionary Python dictionary containing Symbols as key and their corresponding values. Examples ======== There is a beam of length 8 meters. A constant distributed load of 10 KN/m is applied from half of the beam till the end. There are two simple supports below the beam, one at the starting point and another at the ending point of the beam. A pointload of magnitude 5 KN is also applied from top of the beam, at a distance of 4 meters from the starting point. Take E = 200 GPa and I = 400*(10**-6) meter**4. Using the sign convention of downwards forces being positive. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> R1, R2 = symbols('R1, R2') >>> b = Beam(8, 200*(10**9), 400*(10**-6)) >>> b.apply_load(5000, 2, -1) >>> b.apply_load(R1, 0, -1) >>> b.apply_load(R2, 8, -1) >>> b.apply_load(10000, 4, 0, end=8) >>> b.bc_deflection = [(0, 0), (8, 0)] >>> b.solve_for_reaction_loads(R1, R2) >>> b.plot_shear_force() Plot object containing: [0]: cartesian line: -13750*SingularityFunction(x, 0, 0) + 5000*SingularityFunction(x, 2, 0) + 10000*SingularityFunction(x, 4, 1) - 31250*SingularityFunction(x, 8, 0) - 10000*SingularityFunction(x, 8, 1) for x over (0.0, 8.0) """ shear_force = self.shear_force() if subs is None: subs = {} for sym in shear_force.atoms(Symbol): if sym == self.variable: continue if sym not in subs: raise ValueError('Value of %s was not passed.' %sym) if self.length in subs: length = subs[self.length] else: length = self.length return plot(shear_force.subs(subs), (self.variable, 0, length), title='Shear Force', xlabel='position', ylabel='Value', line_color='g') def plot_bending_moment(self, subs=None): """ Returns a plot for Bending moment present in the Beam object. Parameters ========== subs : dictionary Python dictionary containing Symbols as key and their corresponding values. Examples ======== There is a beam of length 8 meters. A constant distributed load of 10 KN/m is applied from half of the beam till the end. There are two simple supports below the beam, one at the starting point and another at the ending point of the beam. A pointload of magnitude 5 KN is also applied from top of the beam, at a distance of 4 meters from the starting point. Take E = 200 GPa and I = 400*(10**-6) meter**4. Using the sign convention of downwards forces being positive. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> R1, R2 = symbols('R1, R2') >>> b = Beam(8, 200*(10**9), 400*(10**-6)) >>> b.apply_load(5000, 2, -1) >>> b.apply_load(R1, 0, -1) >>> b.apply_load(R2, 8, -1) >>> b.apply_load(10000, 4, 0, end=8) >>> b.bc_deflection = [(0, 0), (8, 0)] >>> b.solve_for_reaction_loads(R1, R2) >>> b.plot_bending_moment() Plot object containing: [0]: cartesian line: -13750*SingularityFunction(x, 0, 1) + 5000*SingularityFunction(x, 2, 1) + 5000*SingularityFunction(x, 4, 2) - 31250*SingularityFunction(x, 8, 1) - 5000*SingularityFunction(x, 8, 2) for x over (0.0, 8.0) """ bending_moment = self.bending_moment() if subs is None: subs = {} for sym in bending_moment.atoms(Symbol): if sym == self.variable: continue if sym not in subs: raise ValueError('Value of %s was not passed.' %sym) if self.length in subs: length = subs[self.length] else: length = self.length return plot(bending_moment.subs(subs), (self.variable, 0, length), title='Bending Moment', xlabel='position', ylabel='Value', line_color='b') def plot_slope(self, subs=None): """ Returns a plot for slope of deflection curve of the Beam object. Parameters ========== subs : dictionary Python dictionary containing Symbols as key and their corresponding values. Examples ======== There is a beam of length 8 meters. A constant distributed load of 10 KN/m is applied from half of the beam till the end. There are two simple supports below the beam, one at the starting point and another at the ending point of the beam. A pointload of magnitude 5 KN is also applied from top of the beam, at a distance of 4 meters from the starting point. Take E = 200 GPa and I = 400*(10**-6) meter**4. Using the sign convention of downwards forces being positive. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> R1, R2 = symbols('R1, R2') >>> b = Beam(8, 200*(10**9), 400*(10**-6)) >>> b.apply_load(5000, 2, -1) >>> b.apply_load(R1, 0, -1) >>> b.apply_load(R2, 8, -1) >>> b.apply_load(10000, 4, 0, end=8) >>> b.bc_deflection = [(0, 0), (8, 0)] >>> b.solve_for_reaction_loads(R1, R2) >>> b.plot_slope() Plot object containing: [0]: cartesian line: -8.59375e-5*SingularityFunction(x, 0, 2) + 3.125e-5*SingularityFunction(x, 2, 2) + 2.08333333333333e-5*SingularityFunction(x, 4, 3) - 0.0001953125*SingularityFunction(x, 8, 2) - 2.08333333333333e-5*SingularityFunction(x, 8, 3) + 0.00138541666666667 for x over (0.0, 8.0) """ slope = self.slope() if subs is None: subs = {} for sym in slope.atoms(Symbol): if sym == self.variable: continue if sym not in subs: raise ValueError('Value of %s was not passed.' %sym) if self.length in subs: length = subs[self.length] else: length = self.length return plot(slope.subs(subs), (self.variable, 0, length), title='Slope', xlabel='position', ylabel='Value', line_color='m') def plot_deflection(self, subs=None): """ Returns a plot for deflection curve of the Beam object. Parameters ========== subs : dictionary Python dictionary containing Symbols as key and their corresponding values. Examples ======== There is a beam of length 8 meters. A constant distributed load of 10 KN/m is applied from half of the beam till the end. There are two simple supports below the beam, one at the starting point and another at the ending point of the beam. A pointload of magnitude 5 KN is also applied from top of the beam, at a distance of 4 meters from the starting point. Take E = 200 GPa and I = 400*(10**-6) meter**4. Using the sign convention of downwards forces being positive. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> R1, R2 = symbols('R1, R2') >>> b = Beam(8, 200*(10**9), 400*(10**-6)) >>> b.apply_load(5000, 2, -1) >>> b.apply_load(R1, 0, -1) >>> b.apply_load(R2, 8, -1) >>> b.apply_load(10000, 4, 0, end=8) >>> b.bc_deflection = [(0, 0), (8, 0)] >>> b.solve_for_reaction_loads(R1, R2) >>> b.plot_deflection() Plot object containing: [0]: cartesian line: 0.00138541666666667*x - 2.86458333333333e-5*SingularityFunction(x, 0, 3) + 1.04166666666667e-5*SingularityFunction(x, 2, 3) + 5.20833333333333e-6*SingularityFunction(x, 4, 4) - 6.51041666666667e-5*SingularityFunction(x, 8, 3) - 5.20833333333333e-6*SingularityFunction(x, 8, 4) for x over (0.0, 8.0) """ deflection = self.deflection() if subs is None: subs = {} for sym in deflection.atoms(Symbol): if sym == self.variable: continue if sym not in subs: raise ValueError('Value of %s was not passed.' %sym) if self.length in subs: length = subs[self.length] else: length = self.length return plot(deflection.subs(subs), (self.variable, 0, length), title='Deflection', xlabel='position', ylabel='Value', line_color='r') @doctest_depends_on(modules=('numpy', 'matplotlib',)) def plot_loading_results(self, subs=None): """ Returns Axes object containing subplots of Shear Force, Bending Moment, Slope and Deflection of the Beam object. Parameters ========== subs : dictionary Python dictionary containing Symbols as key and their corresponding values. .. note:: This method only works if numpy and matplotlib libraries are installed on the system. Examples ======== There is a beam of length 8 meters. A constant distributed load of 10 KN/m is applied from half of the beam till the end. There are two simple supports below the beam, one at the starting point and another at the ending point of the beam. A pointload of magnitude 5 KN is also applied from top of the beam, at a distance of 4 meters from the starting point. Take E = 200 GPa and I = 400*(10**-6) meter**4. Using the sign convention of downwards forces being positive. >>> from sympy.physics.continuum_mechanics.beam import Beam >>> from sympy import symbols >>> R1, R2 = symbols('R1, R2') >>> b = Beam(8, 200*(10**9), 400*(10**-6)) >>> b.apply_load(5000, 2, -1) >>> b.apply_load(R1, 0, -1) >>> b.apply_load(R2, 8, -1) >>> b.apply_load(10000, 4, 0, end=8) >>> b.bc_deflection = [(0, 0), (8, 0)] >>> b.solve_for_reaction_loads(R1, R2) >>> axes = b.plot_loading_results() """ if matplotlib is None: raise ImportError('Install matplotlib to use this method.') else: plt = matplotlib.pyplot if numpy is None: raise ImportError('Install numpy to use this method.') else: linspace = numpy.linspace length = self.length variable = self.variable if subs is None: subs = {} for sym in self.deflection().atoms(Symbol): if sym == self.variable: continue if sym not in subs: raise ValueError('Value of %s was not passed.' % sym) if self.length in subs: length = subs[self.length] else: length = self.length # As we are using matplotlib directly in this method, we need to change # SymPy methods to numpy functions. shear = lambdify(variable, self.shear_force().subs(subs).rewrite(Piecewise), 'numpy') moment = lambdify(variable, self.bending_moment().subs(subs).rewrite(Piecewise), 'numpy') slope = lambdify(variable, self.slope().subs(subs).rewrite(Piecewise), 'numpy') deflection = lambdify(variable, self.deflection().subs(subs).rewrite(Piecewise), 'numpy') points = linspace(0, float(length), num=100*length) # Creating a grid for subplots with 2 rows and 2 columns fig, axs = plt.subplots(4, 1) # axs is a 2D-numpy array containing axes axs[0].plot(points, shear(points)) axs[0].set_title("Shear Force") axs[1].plot(points, moment(points)) axs[1].set_title("Bending Moment") axs[2].plot(points, slope(points)) axs[2].set_title("Slope") axs[3].plot(points, deflection(points)) axs[3].set_title("Deflection") fig.tight_layout() # For better spacing between subplots return axs class Beam3D(Beam): """ This class handles loads applied in any direction of a 3D space along with unequal values of Second moment along different axes. .. note:: While solving a beam bending problem, a user should choose its own sign convention and should stick to it. The results will automatically follow the chosen sign convention. This class assumes that any kind of distributed load/moment is applied through out the span of a beam. Examples ======== There is a beam of l meters long. A constant distributed load of magnitude q is applied along y-axis from start till the end of beam. A constant distributed moment of magnitude m is also applied along z-axis from start till the end of beam. Beam is fixed at both of its end. So, deflection of the beam at the both ends is restricted. >>> from sympy.physics.continuum_mechanics.beam import Beam3D >>> from sympy import symbols, simplify >>> l, E, G, I, A = symbols('l, E, G, I, A') >>> b = Beam3D(l, E, G, I, A) >>> x, q, m = symbols('x, q, m') >>> b.apply_load(q, 0, 0, dir="y") >>> b.apply_moment_load(m, 0, -1, dir="z") >>> b.shear_force() [0, -q*x, 0] >>> b.bending_moment() [0, 0, -m*x + q*x**2/2] >>> b.bc_slope = [(0, [0, 0, 0]), (l, [0, 0, 0])] >>> b.bc_deflection = [(0, [0, 0, 0]), (l, [0, 0, 0])] >>> b.solve_slope_deflection() >>> b.slope() [0, 0, l*x*(-l*q + 3*l*(A*G*l*(l*q - 2*m) + 12*E*I*q)/(2*(A*G*l**2 + 12*E*I)) + 3*m)/(6*E*I) + q*x**3/(6*E*I) + x**2*(-l*(A*G*l*(l*q - 2*m) + 12*E*I*q)/(2*(A*G*l**2 + 12*E*I)) - m)/(2*E*I)] >>> dx, dy, dz = b.deflection() >>> dx 0 >>> dz 0 >>> expectedy = ( ... -l**2*q*x**2/(12*E*I) + l**2*x**2*(A*G*l*(l*q - 2*m) + 12*E*I*q)/(8*E*I*(A*G*l**2 + 12*E*I)) ... + l*m*x**2/(4*E*I) - l*x**3*(A*G*l*(l*q - 2*m) + 12*E*I*q)/(12*E*I*(A*G*l**2 + 12*E*I)) - m*x**3/(6*E*I) ... + q*x**4/(24*E*I) + l*x*(A*G*l*(l*q - 2*m) + 12*E*I*q)/(2*A*G*(A*G*l**2 + 12*E*I)) - q*x**2/(2*A*G) ... ) >>> simplify(dy - expectedy) 0 References ========== .. [1] http://homes.civil.aau.dk/jc/FemteSemester/Beams3D.pdf """ def __init__(self, length, elastic_modulus, shear_modulus , second_moment, area, variable=Symbol('x')): """Initializes the class. Parameters ========== length : Sympifyable A Symbol or value representing the Beam's length. elastic_modulus : Sympifyable A SymPy expression representing the Beam's Modulus of Elasticity. It is a measure of the stiffness of the Beam material. shear_modulus : Sympifyable A SymPy expression representing the Beam's Modulus of rigidity. It is a measure of rigidity of the Beam material. second_moment : Sympifyable or list A list of two elements having SymPy expression representing the Beam's Second moment of area. First value represent Second moment across y-axis and second across z-axis. Single SymPy expression can be passed if both values are same area : Sympifyable A SymPy expression representing the Beam's cross-sectional area in a plane prependicular to length of the Beam. variable : Symbol, optional A Symbol object that will be used as the variable along the beam while representing the load, shear, moment, slope and deflection curve. By default, it is set to ``Symbol('x')``. """ self.length = length self.elastic_modulus = elastic_modulus self.shear_modulus = shear_modulus self.second_moment = second_moment self.area = area self.variable = variable self._boundary_conditions = {'deflection': [], 'slope': []} self._load_vector = [0, 0, 0] self._moment_load_vector = [0, 0, 0] self._load_Singularity = [0, 0, 0] self._reaction_loads = {} self._slope = [0, 0, 0] self._deflection = [0, 0, 0] @property def shear_modulus(self): """Young's Modulus of the Beam. """ return self._shear_modulus @shear_modulus.setter def shear_modulus(self, e): self._shear_modulus = sympify(e) @property def second_moment(self): """Second moment of area of the Beam. """ return self._second_moment @second_moment.setter def second_moment(self, i): if isinstance(i, list): i = [sympify(x) for x in i] self._second_moment = i else: self._second_moment = sympify(i) @property def area(self): """Cross-sectional area of the Beam. """ return self._area @area.setter def area(self, a): self._area = sympify(a) @property def load_vector(self): """ Returns a three element list representing the load vector. """ return self._load_vector @property def moment_load_vector(self): """ Returns a three element list representing moment loads on Beam. """ return self._moment_load_vector @property def boundary_conditions(self): """ Returns a dictionary of boundary conditions applied on the beam. The dictionary has two keywords namely slope and deflection. The value of each keyword is a list of tuple, where each tuple contains loaction and value of a boundary condition in the format (location, value). Further each value is a list corresponding to slope or deflection(s) values along three axes at that location. Examples ======== There is a beam of length 4 meters. The slope at 0 should be 4 along the x-axis and 0 along others. At the other end of beam, deflection along all the three axes should be zero. >>> from sympy.physics.continuum_mechanics.beam import Beam3D >>> from sympy import symbols >>> l, E, G, I, A, x = symbols('l, E, G, I, A, x') >>> b = Beam3D(30, E, G, I, A, x) >>> b.bc_slope = [(0, (4, 0, 0))] >>> b.bc_deflection = [(4, [0, 0, 0])] >>> b.boundary_conditions {'deflection': [(4, [0, 0, 0])], 'slope': [(0, (4, 0, 0))]} Here the deflection of the beam should be ``0`` along all the three axes at ``4``. Similarly, the slope of the beam should be ``4`` along x-axis and ``0`` along y and z axis at ``0``. """ return self._boundary_conditions def apply_load(self, value, start, order, dir="y"): """ This method adds up the force load to a particular beam object. Parameters ========== value : Sympifyable The magnitude of an applied load. dir : String Axis along which load is applied. order : Integer The order of the applied load. - For point loads, order=-1 - For constant distributed load, order=0 - For ramp loads, order=1 - For parabolic ramp loads, order=2 - ... so on. """ x = self.variable value = sympify(value) start = sympify(start) order = sympify(order) if dir == "x": if not order == -1: self._load_vector[0] += value self._load_Singularity[0] += value*SingularityFunction(x, start, order) elif dir == "y": if not order == -1: self._load_vector[1] += value self._load_Singularity[1] += value*SingularityFunction(x, start, order) else: if not order == -1: self._load_vector[2] += value self._load_Singularity[2] += value*SingularityFunction(x, start, order) def apply_moment_load(self, value, start, order, dir="y"): """ This method adds up the moment loads to a particular beam object. Parameters ========== value : Sympifyable The magnitude of an applied moment. dir : String Axis along which moment is applied. order : Integer The order of the applied load. - For point moments, order=-2 - For constant distributed moment, order=-1 - For ramp moments, order=0 - For parabolic ramp moments, order=1 - ... so on. """ x = self.variable value = sympify(value) start = sympify(start) order = sympify(order) if dir == "x": if not order == -2: self._moment_load_vector[0] += value self._load_Singularity[0] += value*SingularityFunction(x, start, order) elif dir == "y": if not order == -2: self._moment_load_vector[1] += value self._load_Singularity[0] += value*SingularityFunction(x, start, order) else: if not order == -2: self._moment_load_vector[2] += value self._load_Singularity[0] += value*SingularityFunction(x, start, order) def apply_support(self, loc, type="fixed"): if type == "pin" or type == "roller": reaction_load = Symbol('R_'+str(loc)) self._reaction_loads[reaction_load] = reaction_load self.bc_deflection.append((loc, [0, 0, 0])) else: reaction_load = Symbol('R_'+str(loc)) reaction_moment = Symbol('M_'+str(loc)) self._reaction_loads[reaction_load] = [reaction_load, reaction_moment] self.bc_deflection.append((loc, [0, 0, 0])) self.bc_slope.append((loc, [0, 0, 0])) def solve_for_reaction_loads(self, *reaction): """ Solves for the reaction forces. Examples ======== There is a beam of length 30 meters. It it supported by rollers at of its end. A constant distributed load of magnitude 8 N is applied from start till its end along y-axis. Another linear load having slope equal to 9 is applied along z-axis. >>> from sympy.physics.continuum_mechanics.beam import Beam3D >>> from sympy import symbols >>> l, E, G, I, A, x = symbols('l, E, G, I, A, x') >>> b = Beam3D(30, E, G, I, A, x) >>> b.apply_load(8, start=0, order=0, dir="y") >>> b.apply_load(9*x, start=0, order=0, dir="z") >>> b.bc_deflection = [(0, [0, 0, 0]), (30, [0, 0, 0])] >>> R1, R2, R3, R4 = symbols('R1, R2, R3, R4') >>> b.apply_load(R1, start=0, order=-1, dir="y") >>> b.apply_load(R2, start=30, order=-1, dir="y") >>> b.apply_load(R3, start=0, order=-1, dir="z") >>> b.apply_load(R4, start=30, order=-1, dir="z") >>> b.solve_for_reaction_loads(R1, R2, R3, R4) >>> b.reaction_loads {R1: -120, R2: -120, R3: -1350, R4: -2700} """ x = self.variable l=self.length q = self._load_Singularity m = self._moment_load_vector shear_curves = [integrate(load, x) for load in q] moment_curves = [integrate(shear, x) for shear in shear_curves] for i in range(3): react = [r for r in reaction if (shear_curves[i].has(r) or moment_curves[i].has(r))] if len(react) == 0: continue shear_curve = limit(shear_curves[i], x, l) moment_curve = limit(moment_curves[i], x, l) sol = list((linsolve([shear_curve, moment_curve], react).args)[0]) sol_dict = dict(zip(react, sol)) reaction_loads = self._reaction_loads # Check if any of the evaluated rection exists in another direction # and if it exists then it should have same value. for key in sol_dict: if key in reaction_loads and sol_dict[key] != reaction_loads[key]: raise ValueError("Ambiguous solution for %s in different directions." % key) self._reaction_loads.update(sol_dict) def shear_force(self): """ Returns a list of three expressions which represents the shear force curve of the Beam object along all three axes. """ x = self.variable q = self._load_vector m = self._moment_load_vector return [integrate(-q[0], x), integrate(-q[1], x), integrate(-q[2], x)] def axial_force(self): """ Returns expression of Axial shear force present inside the Beam object. """ return self.shear_force()[0] def bending_moment(self): """ Returns a list of three expressions which represents the bending moment curve of the Beam object along all three axes. """ x = self.variable q = self._load_vector m = self._moment_load_vector shear = self.shear_force() return [integrate(-m[0], x), integrate(-m[1] + shear[2], x), integrate(-m[2] - shear[1], x) ] def torsional_moment(): """ Returns expression of Torsional moment present inside the Beam object. """ return self.bending_moment()[0] def solve_slope_deflection(self): from sympy import dsolve, Function, Derivative, Eq x = self.variable l = self.length E = self.elastic_modulus G = self.shear_modulus I = self.second_moment if isinstance(I, list): I_y, I_z = I[0], I[1] else: I_y = I_z = I A = self.area load = self._load_vector moment = self._moment_load_vector defl = Function('defl') theta = Function('theta') # Finding deflection along x-axis(and corresponding slope value by differentiating it) # Equation used: Derivative(E*A*Derivative(def_x(x), x), x) + load_x = 0 eq = Derivative(E*A*Derivative(defl(x), x), x) + load[0] def_x = dsolve(Eq(eq, 0), defl(x)).args[1] # Solving constants originated from dsolve C1 = Symbol('C1') C2 = Symbol('C2') constants = list((linsolve([def_x.subs(x, 0), def_x.subs(x, l)], C1, C2).args)[0]) def_x = def_x.subs({C1:constants[0], C2:constants[1]}) slope_x = def_x.diff(x) self._deflection[0] = def_x self._slope[0] = slope_x # Finding deflection along y-axis and slope across z-axis. System of equation involved: # 1: Derivative(E*I_z*Derivative(theta_z(x), x), x) + G*A*(Derivative(defl_y(x), x) - theta_z(x)) + moment_z = 0 # 2: Derivative(G*A*(Derivative(defl_y(x), x) - theta_z(x)), x) + load_y = 0 C_i = Symbol('C_i') # Substitute value of `G*A*(Derivative(defl_y(x), x) - theta_z(x))` from (2) in (1) eq1 = Derivative(E*I_z*Derivative(theta(x), x), x) + (integrate(-load[1], x) + C_i) + moment[2] slope_z = dsolve(Eq(eq1, 0)).args[1] # Solve for constants originated from using dsolve on eq1 constants = list((linsolve([slope_z.subs(x, 0), slope_z.subs(x, l)], C1, C2).args)[0]) slope_z = slope_z.subs({C1:constants[0], C2:constants[1]}) # Put value of slope obtained back in (2) to solve for `C_i` and find deflection across y-axis eq2 = G*A*(Derivative(defl(x), x)) + load[1]*x - C_i - G*A*slope_z def_y = dsolve(Eq(eq2, 0), defl(x)).args[1] # Solve for constants originated from using dsolve on eq2 constants = list((linsolve([def_y.subs(x, 0), def_y.subs(x, l)], C1, C_i).args)[0]) self._deflection[1] = def_y.subs({C1:constants[0], C_i:constants[1]}) self._slope[2] = slope_z.subs(C_i, constants[1]) # Finding deflection along z-axis and slope across y-axis. System of equation involved: # 1: Derivative(E*I_y*Derivative(theta_y(x), x), x) - G*A*(Derivative(defl_z(x), x) + theta_y(x)) + moment_y = 0 # 2: Derivative(G*A*(Derivative(defl_z(x), x) + theta_y(x)), x) + load_z = 0 # Substitute value of `G*A*(Derivative(defl_y(x), x) + theta_z(x))` from (2) in (1) eq1 = Derivative(E*I_y*Derivative(theta(x), x), x) + (integrate(load[2], x) - C_i) + moment[1] slope_y = dsolve(Eq(eq1, 0)).args[1] # Solve for constants originated from using dsolve on eq1 constants = list((linsolve([slope_y.subs(x, 0), slope_y.subs(x, l)], C1, C2).args)[0]) slope_y = slope_y.subs({C1:constants[0], C2:constants[1]}) # Put value of slope obtained back in (2) to solve for `C_i` and find deflection across z-axis eq2 = G*A*(Derivative(defl(x), x)) + load[2]*x - C_i + G*A*slope_y def_z = dsolve(Eq(eq2,0)).args[1] # Solve for constants originated from using dsolve on eq2 constants = list((linsolve([def_z.subs(x, 0), def_z.subs(x, l)], C1, C_i).args)[0]) self._deflection[2] = def_z.subs({C1:constants[0], C_i:constants[1]}) self._slope[1] = slope_y.subs(C_i, constants[1]) def slope(self): """ Returns a three element list representing slope of deflection curve along all the three axes. """ return self._slope def deflection(self): """ Returns a three element list representing deflection curve along all the three axes. """ return self._deflection

42437f5e7ba1950bc8227f1993dc5276ed0282a81c698035deeaa00314542445

# -*- coding: utf-8 -*- from sympy.utilities.pytest import warns_deprecated_sympy from sympy import Rational, S from sympy.physics.units.definitions import c, kg, m, s from sympy.physics.units.dimensions import ( Dimension, DimensionSystem, action, current, length, mass, time, velocity) from sympy.physics.units.quantities import Quantity from sympy.physics.units.unitsystem import UnitSystem from sympy.utilities.pytest import raises def test_definition(): # want to test if the system can have several units of the same dimension dm = Quantity("dm") dm.set_dimension(length) dm.set_scale_factor(Rational(1, 10)) base = (m, s) base_dim = (m.dimension, s.dimension) ms = UnitSystem(base, (c, dm), "MS", "MS system") assert set(ms._base_units) == set(base) assert set(ms._units) == set((m, s, c, dm)) #assert ms._units == DimensionSystem._sort_dims(base + (velocity,)) assert ms.name == "MS" assert ms.descr == "MS system" assert ms._system.base_dims == base_dim assert ms._system.derived_dims == (velocity,) def test_error_definition(): raises(ValueError, lambda: UnitSystem((m, s, c))) def test_str_repr(): assert str(UnitSystem((m, s), name="MS")) == "MS" assert str(UnitSystem((m, s))) == "UnitSystem((meter, second))" assert repr(UnitSystem((m, s))) == "<UnitSystem: (%s, %s)>" % (m, s) def test_print_unit_base(): A = Quantity("A") A.set_dimension(current) A.set_scale_factor(S.One) Js = Quantity("Js") Js.set_dimension(action) Js.set_scale_factor(S.One) mksa = UnitSystem((m, kg, s, A), (Js,)) with warns_deprecated_sympy(): assert mksa.print_unit_base(Js) == m**2*kg*s**-1 def test_extend(): ms = UnitSystem((m, s), (c,)) Js = Quantity("Js") Js.set_dimension(action) Js.set_scale_factor(1) mks = ms.extend((kg,), (Js,)) res = UnitSystem((m, s, kg), (c, Js)) assert set(mks._base_units) == set(res._base_units) assert set(mks._units) == set(res._units) def test_dim(): dimsys = UnitSystem((m, kg, s), (c,)) assert dimsys.dim == 3 def test_is_consistent(): assert UnitSystem((m, s)).is_consistent is True

96d9ea7f9e2a210e836bf26f60b70b6f6bd0f125ccb63f2c21bfbf79bf4e2ed8

from sympy import Symbol, symbols, S, simplify from sympy.physics.continuum_mechanics.beam import Beam from sympy.functions import SingularityFunction, Piecewise, meijerg, Abs, log from sympy.utilities.pytest import raises from sympy.physics.units import meter, newton, kilo, giga, milli from sympy.physics.continuum_mechanics.beam import Beam3D x = Symbol('x') y = Symbol('y') R1, R2 = symbols('R1, R2') def test_Beam(): E = Symbol('E') E_1 = Symbol('E_1') I = Symbol('I') I_1 = Symbol('I_1') b = Beam(1, E, I) assert b.length == 1 assert b.elastic_modulus == E assert b.second_moment == I assert b.variable == x # Test the length setter b.length = 4 assert b.length == 4 # Test the E setter b.elastic_modulus = E_1 assert b.elastic_modulus == E_1 # Test the I setter b.second_moment = I_1 assert b.second_moment is I_1 # Test the variable setter b.variable = y assert b.variable is y # Test for all boundary conditions. b.bc_deflection = [(0, 2)] b.bc_slope = [(0, 1)] assert b.boundary_conditions == {'deflection': [(0, 2)], 'slope': [(0, 1)]} # Test for slope boundary condition method b.bc_slope.extend([(4, 3), (5, 0)]) s_bcs = b.bc_slope assert s_bcs == [(0, 1), (4, 3), (5, 0)] # Test for deflection boundary condition method b.bc_deflection.extend([(4, 3), (5, 0)]) d_bcs = b.bc_deflection assert d_bcs == [(0, 2), (4, 3), (5, 0)] # Test for updated boundary conditions bcs_new = b.boundary_conditions assert bcs_new == { 'deflection': [(0, 2), (4, 3), (5, 0)], 'slope': [(0, 1), (4, 3), (5, 0)]} b1 = Beam(30, E, I) b1.apply_load(-8, 0, -1) b1.apply_load(R1, 10, -1) b1.apply_load(R2, 30, -1) b1.apply_load(120, 30, -2) b1.bc_deflection = [(10, 0), (30, 0)] b1.solve_for_reaction_loads(R1, R2) # Test for finding reaction forces p = b1.reaction_loads q = {R1: 6, R2: 2} assert p == q # Test for load distribution function. p = b1.load q = -8*SingularityFunction(x, 0, -1) + 6*SingularityFunction(x, 10, -1) + 120*SingularityFunction(x, 30, -2) + 2*SingularityFunction(x, 30, -1) assert p == q # Test for shear force distribution function p = b1.shear_force() q = -8*SingularityFunction(x, 0, 0) + 6*SingularityFunction(x, 10, 0) + 120*SingularityFunction(x, 30, -1) + 2*SingularityFunction(x, 30, 0) assert p == q # Test for bending moment distribution function p = b1.bending_moment() q = -8*SingularityFunction(x, 0, 1) + 6*SingularityFunction(x, 10, 1) + 120*SingularityFunction(x, 30, 0) + 2*SingularityFunction(x, 30, 1) assert p == q # Test for slope distribution function p = b1.slope() q = -4*SingularityFunction(x, 0, 2) + 3*SingularityFunction(x, 10, 2) + 120*SingularityFunction(x, 30, 1) + SingularityFunction(x, 30, 2) + S(4000)/3 assert p == q/(E*I) # Test for deflection distribution function p = b1.deflection() q = 4000*x/3 - 4*SingularityFunction(x, 0, 3)/3 + SingularityFunction(x, 10, 3) + 60*SingularityFunction(x, 30, 2) + SingularityFunction(x, 30, 3)/3 - 12000 assert p == q/(E*I) # Test using symbols l = Symbol('l') w0 = Symbol('w0') w2 = Symbol('w2') a1 = Symbol('a1') c = Symbol('c') c1 = Symbol('c1') d = Symbol('d') e = Symbol('e') f = Symbol('f') b2 = Beam(l, E, I) b2.apply_load(w0, a1, 1) b2.apply_load(w2, c1, -1) b2.bc_deflection = [(c, d)] b2.bc_slope = [(e, f)] # Test for load distribution function. p = b2.load q = w0*SingularityFunction(x, a1, 1) + w2*SingularityFunction(x, c1, -1) assert p == q # Test for shear force distribution function p = b2.shear_force() q = w0*SingularityFunction(x, a1, 2)/2 + w2*SingularityFunction(x, c1, 0) assert p == q # Test for bending moment distribution function p = b2.bending_moment() q = w0*SingularityFunction(x, a1, 3)/6 + w2*SingularityFunction(x, c1, 1) assert p == q # Test for slope distribution function p = b2.slope() q = (w0*SingularityFunction(x, a1, 4)/24 + w2*SingularityFunction(x, c1, 2)/2)/(E*I) + (E*I*f - w0*SingularityFunction(e, a1, 4)/24 - w2*SingularityFunction(e, c1, 2)/2)/(E*I) assert p == q # Test for deflection distribution function p = b2.deflection() q = x*(E*I*f - w0*SingularityFunction(e, a1, 4)/24 - w2*SingularityFunction(e, c1, 2)/2)/(E*I) + (w0*SingularityFunction(x, a1, 5)/120 + w2*SingularityFunction(x, c1, 3)/6)/(E*I) + (E*I*(-c*f + d) + c*w0*SingularityFunction(e, a1, 4)/24 + c*w2*SingularityFunction(e, c1, 2)/2 - w0*SingularityFunction(c, a1, 5)/120 - w2*SingularityFunction(c, c1, 3)/6)/(E*I) assert p == q b3 = Beam(9, E, I) b3.apply_load(value=-2, start=2, order=2, end=3) b3.bc_slope.append((0, 2)) C3 = symbols('C3') C4 = symbols('C4') p = b3.load q = -2*SingularityFunction(x, 2, 2) + 2*SingularityFunction(x, 3, 0) + 4*SingularityFunction(x, 3, 1) + 2*SingularityFunction(x, 3, 2) assert p == q p = b3.slope() q = 2 + (-SingularityFunction(x, 2, 5)/30 + SingularityFunction(x, 3, 3)/3 + SingularityFunction(x, 3, 4)/6 + SingularityFunction(x, 3, 5)/30)/(E*I) assert p == q p = b3.deflection() q = 2*x + (-SingularityFunction(x, 2, 6)/180 + SingularityFunction(x, 3, 4)/12 + SingularityFunction(x, 3, 5)/30 + SingularityFunction(x, 3, 6)/180)/(E*I) assert p == q + C4 b4 = Beam(4, E, I) b4.apply_load(-3, 0, 0, end=3) p = b4.load q = -3*SingularityFunction(x, 0, 0) + 3*SingularityFunction(x, 3, 0) assert p == q p = b4.slope() q = -3*SingularityFunction(x, 0, 3)/6 + 3*SingularityFunction(x, 3, 3)/6 assert p == q/(E*I) + C3 p = b4.deflection() q = -3*SingularityFunction(x, 0, 4)/24 + 3*SingularityFunction(x, 3, 4)/24 assert p == q/(E*I) + C3*x + C4 # can't use end with point loads raises(ValueError, lambda: b4.apply_load(-3, 0, -1, end=3)) with raises(TypeError): b4.variable = 1 def test_insufficient_bconditions(): # Test cases when required number of boundary conditions # are not provided to solve the integration constants. L = symbols('L', positive=True) E, I, P, a3, a4 = symbols('E I P a3 a4') b = Beam(L, E, I, base_char='a') b.apply_load(R2, L, -1) b.apply_load(R1, 0, -1) b.apply_load(-P, L/2, -1) b.solve_for_reaction_loads(R1, R2) p = b.slope() q = P*SingularityFunction(x, 0, 2)/4 - P*SingularityFunction(x, L/2, 2)/2 + P*SingularityFunction(x, L, 2)/4 assert p == q/(E*I) + a3 p = b.deflection() q = P*SingularityFunction(x, 0, 3)/12 - P*SingularityFunction(x, L/2, 3)/6 + P*SingularityFunction(x, L, 3)/12 assert p == q/(E*I) + a3*x + a4 b.bc_deflection = [(0, 0)] p = b.deflection() q = a3*x + P*SingularityFunction(x, 0, 3)/12 - P*SingularityFunction(x, L/2, 3)/6 + P*SingularityFunction(x, L, 3)/12 assert p == q/(E*I) b.bc_deflection = [(0, 0), (L, 0)] p = b.deflection() q = -L**2*P*x/16 + P*SingularityFunction(x, 0, 3)/12 - P*SingularityFunction(x, L/2, 3)/6 + P*SingularityFunction(x, L, 3)/12 assert p == q/(E*I) def test_statically_indeterminate(): E = Symbol('E') I = Symbol('I') M1, M2 = symbols('M1, M2') F = Symbol('F') l = Symbol('l', positive=True) b5 = Beam(l, E, I) b5.bc_deflection = [(0, 0),(l, 0)] b5.bc_slope = [(0, 0),(l, 0)] b5.apply_load(R1, 0, -1) b5.apply_load(M1, 0, -2) b5.apply_load(R2, l, -1) b5.apply_load(M2, l, -2) b5.apply_load(-F, l/2, -1) b5.solve_for_reaction_loads(R1, R2, M1, M2) p = b5.reaction_loads q = {R1: F/2, R2: F/2, M1: -F*l/8, M2: F*l/8} assert p == q def test_beam_units(): E = Symbol('E') I = Symbol('I') R1, R2 = symbols('R1, R2') b = Beam(8*meter, 200*giga*newton/meter**2, 400*1000000*(milli*meter)**4) b.apply_load(5*kilo*newton, 2*meter, -1) b.apply_load(R1, 0*meter, -1) b.apply_load(R2, 8*meter, -1) b.apply_load(10*kilo*newton/meter, 4*meter, 0, end=8*meter) b.bc_deflection = [(0*meter, 0*meter), (8*meter, 0*meter)] b.solve_for_reaction_loads(R1, R2) assert b.reaction_loads == {R1: -13750*newton, R2: -31250*newton} b = Beam(3*meter, E*newton/meter**2, I*meter**4) b.apply_load(8*kilo*newton, 1*meter, -1) b.apply_load(R1, 0*meter, -1) b.apply_load(R2, 3*meter, -1) b.apply_load(12*kilo*newton*meter, 2*meter, -2) b.bc_deflection = [(0*meter, 0*meter), (3*meter, 0*meter)] b.solve_for_reaction_loads(R1, R2) assert b.reaction_loads == {R1: -28000*newton/3, R2: 4000*newton/3} assert b.deflection().subs(x, 1*meter) == 62000*meter/(9*E*I) def test_variable_moment(): E = Symbol('E') I = Symbol('I') b = Beam(4, E, 2*(4 - x)) b.apply_load(20, 4, -1) R, M = symbols('R, M') b.apply_load(R, 0, -1) b.apply_load(M, 0, -2) b.bc_deflection = [(0, 0)] b.bc_slope = [(0, 0)] b.solve_for_reaction_loads(R, M) assert b.slope().expand() == ((10*x*SingularityFunction(x, 0, 0) - 10*(x - 4)*SingularityFunction(x, 4, 0))/E).expand() assert b.deflection().expand() == ((5*x**2*SingularityFunction(x, 0, 0) - 10*Piecewise((0, Abs(x)/4 < 1), (16*meijerg(((3, 1), ()), ((), (2, 0)), x/4), True)) + 40*SingularityFunction(x, 4, 1))/E).expand() b = Beam(4, E - x, I) b.apply_load(20, 4, -1) R, M = symbols('R, M') b.apply_load(R, 0, -1) b.apply_load(M, 0, -2) b.bc_deflection = [(0, 0)] b.bc_slope = [(0, 0)] b.solve_for_reaction_loads(R, M) assert b.slope().expand() == ((-80*(-log(-E) + log(-E + x))*SingularityFunction(x, 0, 0) + 80*(-log(-E + 4) + log(-E + x))*SingularityFunction(x, 4, 0) + 20*(-E*log(-E) + E*log(-E + x) + x)*SingularityFunction(x, 0, 0) - 20*(-E*log(-E + 4) + E*log(-E + x) + x - 4)*SingularityFunction(x, 4, 0))/I).expand() def test_composite_beam(): E = Symbol('E') I = Symbol('I') b1 = Beam(2, E, 1.5*I) b2 = Beam(2, E, I) b = b1.join(b2, "fixed") b.apply_load(-20, 0, -1) b.apply_load(80, 0, -2) b.apply_load(20, 4, -1) b.bc_slope = [(0, 0)] b.bc_deflection = [(0, 0)] assert b.length == 4 assert b.second_moment == Piecewise((1.5*I, x <= 2), (I, x <= 4)) assert b.slope().subs(x, 4) == 120.0/(E*I) assert b.slope().subs(x, 2) == 80.0/(E*I) assert int(b.deflection().subs(x, 4).args[0]) == 302 # Coefficient of 1/(E*I) l = symbols('l', positive=True) R1, M1, R2, R3, P = symbols('R1 M1 R2 R3 P') b1 = Beam(2*l, E, I) b2 = Beam(2*l, E, I) b = b1.join(b2,"hinge") b.apply_load(M1, 0, -2) b.apply_load(R1, 0, -1) b.apply_load(R2, l, -1) b.apply_load(R3, 4*l, -1) b.apply_load(P, 3*l, -1) b.bc_slope = [(0, 0)] b.bc_deflection = [(0, 0), (l, 0), (4*l, 0)] b.solve_for_reaction_loads(M1, R1, R2, R3) assert b.reaction_loads == {R3: -P/2, R2: -5*P/4, M1: -P*l/4, R1: 3*P/4} assert b.slope().subs(x, 3*l) == -7*P*l**2/(48*E*I) assert b.deflection().subs(x, 2*l) == 7*P*l**3/(24*E*I) assert b.deflection().subs(x, 3*l) == 5*P*l**3/(16*E*I) # When beams having same second moment are joined. b1 = Beam(2, 500, 10) b2 = Beam(2, 500, 10) b = b1.join(b2, "fixed") b.apply_load(M1, 0, -2) b.apply_load(R1, 0, -1) b.apply_load(R2, 1, -1) b.apply_load(R3, 4, -1) b.apply_load(10, 3, -1) b.bc_slope = [(0, 0)] b.bc_deflection = [(0, 0), (1, 0), (4, 0)] b.solve_for_reaction_loads(M1, R1, R2, R3) assert b.slope() == -2*SingularityFunction(x, 0, 1)/5625 + SingularityFunction(x, 0, 2)/1875\ - 133*SingularityFunction(x, 1, 2)/135000 + SingularityFunction(x, 3, 2)/1000\ - 37*SingularityFunction(x, 4, 2)/67500 assert b.deflection() == -SingularityFunction(x, 0, 2)/5625 + SingularityFunction(x, 0, 3)/5625\ - 133*SingularityFunction(x, 1, 3)/405000 + SingularityFunction(x, 3, 3)/3000\ - 37*SingularityFunction(x, 4, 3)/202500 def test_point_cflexure(): E = Symbol('E') I = Symbol('I') b = Beam(10, E, I) b.apply_load(-4, 0, -1) b.apply_load(-46, 6, -1) b.apply_load(10, 2, -1) b.apply_load(20, 4, -1) b.apply_load(3, 6, 0) assert b.point_cflexure() == [S(10)/3] def test_remove_load(): E = Symbol('E') I = Symbol('I') b = Beam(4, E, I) try: b.remove_load(2, 1, -1) # As no load is applied on beam, ValueError should be returned. except ValueError: assert True else: assert False b.apply_load(-3, 0, -2) b.apply_load(4, 2, -1) b.apply_load(-2, 2, 2, end = 3) b.remove_load(-2, 2, 2, end = 3) assert b.load == -3*SingularityFunction(x, 0, -2) + 4*SingularityFunction(x, 2, -1) assert b.applied_loads == [(-3, 0, -2, None), (4, 2, -1, None)] try: b.remove_load(1, 2, -1) # As load of this magnitude was never applied at # this position, method should return a ValueError. except ValueError: assert True else: assert False b.remove_load(-3, 0, -2) b.remove_load(4, 2, -1) assert b.load == 0 assert b.applied_loads == [] def test_apply_support(): E = Symbol('E') I = Symbol('I') b = Beam(4, E, I) b.apply_support(0, "cantilever") b.apply_load(20, 4, -1) M_0, R_0 = symbols('M_0, R_0') b.solve_for_reaction_loads(R_0, M_0) assert b.slope() == (80*SingularityFunction(x, 0, 1) - 10*SingularityFunction(x, 0, 2) + 10*SingularityFunction(x, 4, 2))/(E*I) assert b.deflection() == (40*SingularityFunction(x, 0, 2) - 10*SingularityFunction(x, 0, 3)/3 + 10*SingularityFunction(x, 4, 3)/3)/(E*I) b = Beam(30, E, I) b.apply_support(10, "pin") b.apply_support(30, "roller") b.apply_load(-8, 0, -1) b.apply_load(120, 30, -2) R_10, R_30 = symbols('R_10, R_30') b.solve_for_reaction_loads(R_10, R_30) assert b.slope() == (-4*SingularityFunction(x, 0, 2) + 3*SingularityFunction(x, 10, 2) + 120*SingularityFunction(x, 30, 1) + SingularityFunction(x, 30, 2) + S(4000)/3)/(E*I) assert b.deflection() == (4000*x/3 - 4*SingularityFunction(x, 0, 3)/3 + SingularityFunction(x, 10, 3) + 60*SingularityFunction(x, 30, 2) + SingularityFunction(x, 30, 3)/3 - 12000)/(E*I) P = Symbol('P', positive=True) L = Symbol('L', positive=True) b = Beam(L, E, I) b.apply_support(0, type='fixed') b.apply_support(L, type='fixed') b.apply_load(-P, L/2, -1) R_0, R_L, M_0, M_L = symbols('R_0, R_L, M_0, M_L') b.solve_for_reaction_loads(R_0, R_L, M_0, M_L) assert b.reaction_loads == {R_0: P/2, R_L: P/2, M_0: -L*P/8, M_L: L*P/8} def max_shear_force(self): E = Symbol('E') I = Symbol('I') b = Beam(3, E, I) R, M = symbols('R, M') b.apply_load(R, 0, -1) b.apply_load(M, 0, -2) b.apply_load(2, 3, -1) b.apply_load(4, 2, -1) b.apply_load(2, 2, 0, end=3) b.solve_for_reaction_loads(R, M) assert b.max_shear_force() == (Interval(0, 2), 8) l = symbols('l', positive=True) P = Symbol('P') b = Beam(l, E, I) R1, R2 = symbols('R1, R2') b.apply_load(R1, 0, -1) b.apply_load(R2, l, -1) b.apply_load(P, 0, 0, end=l) b.solve_for_reaction_loads(R1, R2) assert b.max_shear_force() == (0, l*Abs(P)/2) def test_max_bmoment(): E = Symbol('E') I = Symbol('I') l, P = symbols('l, P', positive=True) b = Beam(l, E, I) R1, R2 = symbols('R1, R2') b.apply_load(R1, 0, -1) b.apply_load(R2, l, -1) b.apply_load(P, l/2, -1) b.solve_for_reaction_loads(R1, R2) b.reaction_loads assert b.max_bmoment() == (l/2, P*l/4) b = Beam(l, E, I) R1, R2 = symbols('R1, R2') b.apply_load(R1, 0, -1) b.apply_load(R2, l, -1) b.apply_load(P, 0, 0, end=l) b.solve_for_reaction_loads(R1, R2) assert b.max_bmoment() == (l/2, P*l**2/8) def test_max_deflection(): E, I, l, F = symbols('E, I, l, F', positive=True) b = Beam(l, E, I) b.bc_deflection = [(0, 0),(l, 0)] b.bc_slope = [(0, 0),(l, 0)] b.apply_load(F/2, 0, -1) b.apply_load(-F*l/8, 0, -2) b.apply_load(F/2, l, -1) b.apply_load(F*l/8, l, -2) b.apply_load(-F, l/2, -1) assert b.max_deflection() == (l/2, F*l**3/(192*E*I)) def test_Beam3D(): l, E, G, I, A = symbols('l, E, G, I, A') R1, R2, R3, R4 = symbols('R1, R2, R3, R4') b = Beam3D(l, E, G, I, A) m, q = symbols('m, q') b.apply_load(q, 0, 0, dir="y") b.apply_moment_load(m, 0, 0, dir="z") b.bc_slope = [(0, [0, 0, 0]), (l, [0, 0, 0])] b.bc_deflection = [(0, [0, 0, 0]), (l, [0, 0, 0])] b.solve_slope_deflection() assert b.shear_force() == [0, -q*x, 0] assert b.bending_moment() == [0, 0, -m*x + q*x**2/2] expected_deflection = (-l**2*q*x**2/(12*E*I) + l**2*x**2*(A*G*l*(l*q - 2*m) + 12*E*I*q)/(8*E*I*(A*G*l**2 + 12*E*I)) + l*m*x**2/(4*E*I) - l*x**3*(A*G*l*(l*q - 2*m) + 12*E*I*q)/(12*E*I*(A*G*l**2 + 12*E*I)) - m*x**3/(6*E*I) + q*x**4/(24*E*I) + l*x*(A*G*l*(l*q - 2*m) + 12*E*I*q)/(2*A*G*(A*G*l**2 + 12*E*I)) - q*x**2/(2*A*G) ) dx, dy, dz = b.deflection() assert dx == dz == 0 assert simplify(dy - expected_deflection) == 0 # == doesn't work b2 = Beam3D(30, E, G, I, A, x) b2.apply_load(50, start=0, order=0, dir="y") b2.bc_deflection = [(0, [0, 0, 0]), (30, [0, 0, 0])] b2.apply_load(R1, start=0, order=-1, dir="y") b2.apply_load(R2, start=30, order=-1, dir="y") b2.solve_for_reaction_loads(R1, R2) assert b2.reaction_loads == {R1: -750, R2: -750} b2.solve_slope_deflection() assert b2.slope() == [0, 0, 25*x**3/(3*E*I) - 375*x**2/(E*I) + 3750*x/(E*I)] expected_deflection = (25*x**4/(12*E*I) - 125*x**3/(E*I) + 1875*x**2/(E*I) - 25*x**2/(A*G) + 750*x/(A*G)) dx, dy, dz = b2.deflection() assert dx == dz == 0 assert simplify(dy - expected_deflection) == 0 # == doesn't work # Test for solve_for_reaction_loads b3 = Beam3D(30, E, G, I, A, x) b3.apply_load(8, start=0, order=0, dir="y") b3.apply_load(9*x, start=0, order=0, dir="z") b3.apply_load(R1, start=0, order=-1, dir="y") b3.apply_load(R2, start=30, order=-1, dir="y") b3.apply_load(R3, start=0, order=-1, dir="z") b3.apply_load(R4, start=30, order=-1, dir="z") b3.solve_for_reaction_loads(R1, R2, R3, R4) assert b3.reaction_loads == {R1: -120, R2: -120, R3: -1350, R4: -2700} def test_parabolic_loads(): E, I, L = symbols('E, I, L', positive=True, real=True) R, M, P = symbols('R, M, P', real=True) # cantilever beam fixed at x=0 and parabolic distributed loading across # length of beam beam = Beam(L, E, I) beam.bc_deflection.append((0, 0)) beam.bc_slope.append((0, 0)) beam.apply_load(R, 0, -1) beam.apply_load(M, 0, -2) # parabolic load beam.apply_load(1, 0, 2) beam.solve_for_reaction_loads(R, M) assert beam.reaction_loads[R] == -L**3 / 3 # cantilever beam fixed at x=0 and parabolic distributed loading across # first half of beam beam = Beam(2 * L, E, I) beam.bc_deflection.append((0, 0)) beam.bc_slope.append((0, 0)) beam.apply_load(R, 0, -1) beam.apply_load(M, 0, -2) # parabolic load from x=0 to x=L beam.apply_load(1, 0, 2, end=L) beam.solve_for_reaction_loads(R, M) # result should be the same as the prior example assert beam.reaction_loads[R] == -L**3 / 3 # check constant load beam = Beam(2 * L, E, I) beam.apply_load(P, 0, 0, end=L) loading = beam.load.xreplace({L: 10, E: 20, I: 30, P: 40}) assert loading.xreplace({x: 5}) == 40 assert loading.xreplace({x: 15}) == 0 # check ramp load beam = Beam(2 * L, E, I) beam.apply_load(P, 0, 1, end=L) assert beam.load == (P*SingularityFunction(x, 0, 1) - P*SingularityFunction(x, L, 1) - P*L*SingularityFunction(x, L, 0)) # check higher order load: x**8 load from x=0 to x=L beam = Beam(2 * L, E, I) beam.apply_load(P, 0, 8, end=L) loading = beam.load.xreplace({L: 10, E: 20, I: 30, P: 40}) assert loading.xreplace({x: 5}) == 40 * 5**8 assert loading.xreplace({x: 15}) == 0

52f694fca5d65703c50ad265564d4780a1b13672f51eca9241a9fe136bf600e2

from __future__ import print_function, division from sympy import Basic from sympy.core.compatibility import SYMPY_INTS, Iterable import itertools class NDimArray(object): """ Examples ======== Create an N-dim array of zeros: >>> from sympy import MutableDenseNDimArray >>> a = MutableDenseNDimArray.zeros(2, 3, 4) >>> a [[[0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0]], [[0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0]]] Create an N-dim array from a list; >>> a = MutableDenseNDimArray([[2, 3], [4, 5]]) >>> a [[2, 3], [4, 5]] >>> b = MutableDenseNDimArray([[[1, 2], [3, 4], [5, 6]], [[7, 8], [9, 10], [11, 12]]]) >>> b [[[1, 2], [3, 4], [5, 6]], [[7, 8], [9, 10], [11, 12]]] Create an N-dim array from a flat list with dimension shape: >>> a = MutableDenseNDimArray([1, 2, 3, 4, 5, 6], (2, 3)) >>> a [[1, 2, 3], [4, 5, 6]] Create an N-dim array from a matrix: >>> from sympy import Matrix >>> a = Matrix([[1,2],[3,4]]) >>> a Matrix([ [1, 2], [3, 4]]) >>> b = MutableDenseNDimArray(a) >>> b [[1, 2], [3, 4]] Arithmetic operations on N-dim arrays >>> a = MutableDenseNDimArray([1, 1, 1, 1], (2, 2)) >>> b = MutableDenseNDimArray([4, 4, 4, 4], (2, 2)) >>> c = a + b >>> c [[5, 5], [5, 5]] >>> a - b [[-3, -3], [-3, -3]] """ _diff_wrt = True def __new__(cls, iterable, shape=None, **kwargs): from sympy.tensor.array import ImmutableDenseNDimArray return ImmutableDenseNDimArray(iterable, shape, **kwargs) def _parse_index(self, index): if isinstance(index, (SYMPY_INTS, Integer)): if index >= self._loop_size: raise ValueError("index out of range") return index if len(index) != self._rank: raise ValueError('Wrong number of array axes') real_index = 0 # check if input index can exist in current indexing for i in range(self._rank): if index[i] >= self.shape[i]: raise ValueError('Index ' + str(index) + ' out of border') real_index = real_index*self.shape[i] + index[i] return real_index def _get_tuple_index(self, integer_index): index = [] for i, sh in enumerate(reversed(self.shape)): index.append(integer_index % sh) integer_index //= sh index.reverse() return tuple(index) def _check_symbolic_index(self, index): # Check if any index is symbolic: tuple_index = (index if isinstance(index, tuple) else (index,)) if any([(isinstance(i, Expr) and (not i.is_number)) for i in tuple_index]): for i, nth_dim in zip(tuple_index, self.shape): if ((i < 0) == True) or ((i >= nth_dim) == True): raise ValueError("index out of range") from sympy.tensor import Indexed return Indexed(self, *tuple_index) return None def _setter_iterable_check(self, value): from sympy.matrices.matrices import MatrixBase if isinstance(value, (Iterable, MatrixBase, NDimArray)): raise NotImplementedError @classmethod def _scan_iterable_shape(cls, iterable): def f(pointer): if not isinstance(pointer, Iterable): return [pointer], () result = [] elems, shapes = zip(*[f(i) for i in pointer]) if len(set(shapes)) != 1: raise ValueError("could not determine shape unambiguously") for i in elems: result.extend(i) return result, (len(shapes),)+shapes[0] return f(iterable) @classmethod def _handle_ndarray_creation_inputs(cls, iterable=None, shape=None, **kwargs): from sympy.matrices.matrices import MatrixBase if shape is None and iterable is None: shape = () iterable = () # Construction from another `NDimArray`: elif shape is None and isinstance(iterable, NDimArray): shape = iterable.shape iterable = list(iterable) # Construct N-dim array from an iterable (numpy arrays included): elif shape is None and isinstance(iterable, Iterable): iterable, shape = cls._scan_iterable_shape(iterable) # Construct N-dim array from a Matrix: elif shape is None and isinstance(iterable, MatrixBase): shape = iterable.shape # Construct N-dim array from another N-dim array: elif shape is None and isinstance(iterable, NDimArray): shape = iterable.shape # Construct NDimArray(iterable, shape) elif shape is not None: pass else: shape = () iterable = (iterable,) if isinstance(shape, (SYMPY_INTS, Integer)): shape = (shape,) if any([not isinstance(dim, (SYMPY_INTS, Integer)) for dim in shape]): raise TypeError("Shape should contain integers only.") return tuple(shape), iterable def __len__(self): """Overload common function len(). Returns number of elements in array. Examples ======== >>> from sympy import MutableDenseNDimArray >>> a = MutableDenseNDimArray.zeros(3, 3) >>> a [[0, 0, 0], [0, 0, 0], [0, 0, 0]] >>> len(a) 9 """ return self._loop_size @property def shape(self): """ Returns array shape (dimension). Examples ======== >>> from sympy import MutableDenseNDimArray >>> a = MutableDenseNDimArray.zeros(3, 3) >>> a.shape (3, 3) """ return self._shape def rank(self): """ Returns rank of array. Examples ======== >>> from sympy import MutableDenseNDimArray >>> a = MutableDenseNDimArray.zeros(3,4,5,6,3) >>> a.rank() 5 """ return self._rank def diff(self, *args, **kwargs): """ Calculate the derivative of each element in the array. Examples ======== >>> from sympy import ImmutableDenseNDimArray >>> from sympy.abc import x, y >>> M = ImmutableDenseNDimArray([[x, y], [1, x*y]]) >>> M.diff(x) [[1, 0], [0, y]] """ from sympy import Derivative kwargs.setdefault('evaluate', True) return Derivative(self.as_immutable(), *args, **kwargs) def _accept_eval_derivative(self, s): return s._visit_eval_derivative_array(self) def _visit_eval_derivative_scalar(self, base): # Types are (base: scalar, self: array) return self.applyfunc(lambda x: base.diff(x)) def _visit_eval_derivative_array(self, base): # Types are (base: array/matrix, self: array) from sympy import derive_by_array return derive_by_array(base, self) def _eval_derivative_n_times(self, s, n): return Basic._eval_derivative_n_times(self, s, n) def _eval_derivative(self, arg): from sympy import derive_by_array from sympy import Derivative, Tuple from sympy.matrices.common import MatrixCommon if isinstance(arg, (Iterable, Tuple, MatrixCommon, NDimArray)): return derive_by_array(self, arg) else: return self.applyfunc(lambda x: x.diff(arg)) def applyfunc(self, f): """Apply a function to each element of the N-dim array. Examples ======== >>> from sympy import ImmutableDenseNDimArray >>> m = ImmutableDenseNDimArray([i*2+j for i in range(2) for j in range(2)], (2, 2)) >>> m [[0, 1], [2, 3]] >>> m.applyfunc(lambda i: 2*i) [[0, 2], [4, 6]] """ return type(self)(map(f, self), self.shape) def __str__(self): """Returns string, allows to use standard functions print() and str(). Examples ======== >>> from sympy import MutableDenseNDimArray >>> a = MutableDenseNDimArray.zeros(2, 2) >>> a [[0, 0], [0, 0]] """ def f(sh, shape_left, i, j): if len(shape_left) == 1: return "["+", ".join([str(self[e]) for e in range(i, j)])+"]" sh //= shape_left[0] return "[" + ", ".join([f(sh, shape_left[1:], i+e*sh, i+(e+1)*sh) for e in range(shape_left[0])]) + "]" # + "\n"*len(shape_left) if self.rank() == 0: return self[()].__str__() return f(self._loop_size, self.shape, 0, self._loop_size) def __repr__(self): return self.__str__() # We don't define _repr_png_ here because it would add a large amount of # data to any notebook containing SymPy expressions, without adding # anything useful to the notebook. It can still enabled manually, e.g., # for the qtconsole, with init_printing(). def _repr_latex_(self): """ IPython/Jupyter LaTeX printing To change the behavior of this (e.g., pass in some settings to LaTeX), use init_printing(). init_printing() will also enable LaTeX printing for built in numeric types like ints and container types that contain SymPy objects, like lists and dictionaries of expressions. """ from sympy.printing.latex import latex s = latex(self, mode='plain') return "$\\displaystyle %s$" % s _repr_latex_orig = _repr_latex_ def tolist(self): """ Converting MutableDenseNDimArray to one-dim list Examples ======== >>> from sympy import MutableDenseNDimArray >>> a = MutableDenseNDimArray([1, 2, 3, 4], (2, 2)) >>> a [[1, 2], [3, 4]] >>> b = a.tolist() >>> b [[1, 2], [3, 4]] """ def f(sh, shape_left, i, j): if len(shape_left) == 1: return [self[e] for e in range(i, j)] result = [] sh //= shape_left[0] for e in range(shape_left[0]): result.append(f(sh, shape_left[1:], i+e*sh, i+(e+1)*sh)) return result return f(self._loop_size, self.shape, 0, self._loop_size) def __add__(self, other): if not isinstance(other, NDimArray): raise TypeError(str(other)) if self.shape != other.shape: raise ValueError("array shape mismatch") result_list = [i+j for i,j in zip(self, other)] return type(self)(result_list, self.shape) def __sub__(self, other): if not isinstance(other, NDimArray): raise TypeError(str(other)) if self.shape != other.shape: raise ValueError("array shape mismatch") result_list = [i-j for i,j in zip(self, other)] return type(self)(result_list, self.shape) def __mul__(self, other): from sympy.matrices.matrices import MatrixBase if isinstance(other, (Iterable, NDimArray, MatrixBase)): raise ValueError("scalar expected, use tensorproduct(...) for tensorial product") other = sympify(other) result_list = [i*other for i in self] return type(self)(result_list, self.shape) def __rmul__(self, other): from sympy.matrices.matrices import MatrixBase if isinstance(other, (Iterable, NDimArray, MatrixBase)): raise ValueError("scalar expected, use tensorproduct(...) for tensorial product") other = sympify(other) result_list = [other*i for i in self] return type(self)(result_list, self.shape) def __div__(self, other): from sympy.matrices.matrices import MatrixBase if isinstance(other, (Iterable, NDimArray, MatrixBase)): raise ValueError("scalar expected") other = sympify(other) result_list = [i/other for i in self] return type(self)(result_list, self.shape) def __rdiv__(self, other): raise NotImplementedError('unsupported operation on NDimArray') def __neg__(self): result_list = [-i for i in self] return type(self)(result_list, self.shape) def __eq__(self, other): """ NDimArray instances can be compared to each other. Instances equal if they have same shape and data. Examples ======== >>> from sympy import MutableDenseNDimArray >>> a = MutableDenseNDimArray.zeros(2, 3) >>> b = MutableDenseNDimArray.zeros(2, 3) >>> a == b True >>> c = a.reshape(3, 2) >>> c == b False >>> a[0,0] = 1 >>> b[0,0] = 2 >>> a == b False """ if not isinstance(other, NDimArray): return False return (self.shape == other.shape) and (list(self) == list(other)) def __ne__(self, other): return not self == other __truediv__ = __div__ __rtruediv__ = __rdiv__ def _eval_transpose(self): if self.rank() != 2: raise ValueError("array rank not 2") from .arrayop import permutedims return permutedims(self, (1, 0)) def transpose(self): return self._eval_transpose() def _eval_conjugate(self): return self.func([i.conjugate() for i in self], self.shape) def conjugate(self): return self._eval_conjugate() def _eval_adjoint(self): return self.transpose().conjugate() def adjoint(self): return self._eval_adjoint() def _slice_expand(self, s, dim): if not isinstance(s, slice): return (s,) start, stop, step = s.indices(dim) return [start + i*step for i in range((stop-start)//step)] def _get_slice_data_for_array_access(self, index): sl_factors = [self._slice_expand(i, dim) for (i, dim) in zip(index, self.shape)] eindices = itertools.product(*sl_factors) return sl_factors, eindices def _get_slice_data_for_array_assignment(self, index, value): if not isinstance(value, NDimArray): value = type(self)(value) sl_factors, eindices = self._get_slice_data_for_array_access(index) slice_offsets = [min(i) if isinstance(i, list) else None for i in sl_factors] # TODO: add checks for dimensions for `value`? return value, eindices, slice_offsets @classmethod def _check_special_bounds(cls, flat_list, shape): if shape == () and len(flat_list) != 1: raise ValueError("arrays without shape need one scalar value") if shape == (0,) and len(flat_list) > 0: raise ValueError("if array shape is (0,) there cannot be elements") class ImmutableNDimArray(NDimArray, Basic): _op_priority = 11.0 def __hash__(self): return Basic.__hash__(self) def as_immutable(self): return self def as_mutable(self): raise NotImplementedError("abstract method") from sympy.core.numbers import Integer from sympy.core.sympify import sympify from sympy.core.function import Derivative from sympy.core.expr import Expr

796469fbe515aa05e39a77022e4baefd5e190c71489e16d03a358eff69c94c9d

import random from sympy import ( Abs, Add, E, Float, I, Integer, Max, Min, N, Poly, Pow, PurePoly, Rational, S, Symbol, cos, exp, expand_mul, oo, pi, signsimp, simplify, sin, sqrt, symbols, sympify, trigsimp, tan, sstr, diff, Function) from sympy.matrices.matrices import (ShapeError, MatrixError, NonSquareMatrixError, DeferredVector, _find_reasonable_pivot_naive, _simplify) from sympy.matrices import ( GramSchmidt, ImmutableMatrix, ImmutableSparseMatrix, Matrix, SparseMatrix, casoratian, diag, eye, hessian, matrix_multiply_elementwise, ones, randMatrix, rot_axis1, rot_axis2, rot_axis3, wronskian, zeros, MutableDenseMatrix, ImmutableDenseMatrix) from sympy.core.compatibility import long, iterable, range, Hashable from sympy.core import Tuple from sympy.utilities.iterables import flatten, capture from sympy.utilities.pytest import raises, XFAIL, slow, skip, warns_deprecated_sympy from sympy.solvers import solve from sympy.assumptions import Q from sympy.tensor.array import Array from sympy.abc import a, b, c, d, x, y, z, t # don't re-order this list classes = (Matrix, SparseMatrix, ImmutableMatrix, ImmutableSparseMatrix) def test_args(): for c, cls in enumerate(classes): m = cls.zeros(3, 2) # all should give back the same type of arguments, e.g. ints for shape assert m.shape == (3, 2) and all(type(i) is int for i in m.shape) assert m.rows == 3 and type(m.rows) is int assert m.cols == 2 and type(m.cols) is int if not c % 2: assert type(m._mat) in (list, tuple, Tuple) else: assert type(m._smat) is dict def test_division(): v = Matrix(1, 2, [x, y]) assert v.__div__(z) == Matrix(1, 2, [x/z, y/z]) assert v.__truediv__(z) == Matrix(1, 2, [x/z, y/z]) assert v/z == Matrix(1, 2, [x/z, y/z]) def test_sum(): m = Matrix([[1, 2, 3], [x, y, x], [2*y, -50, z*x]]) assert m + m == Matrix([[2, 4, 6], [2*x, 2*y, 2*x], [4*y, -100, 2*z*x]]) n = Matrix(1, 2, [1, 2]) raises(ShapeError, lambda: m + n) def test_abs(): m = Matrix(1, 2, [-3, x]) n = Matrix(1, 2, [3, Abs(x)]) assert abs(m) == n def test_addition(): a = Matrix(( (1, 2), (3, 1), )) b = Matrix(( (1, 2), (3, 0), )) assert a + b == a.add(b) == Matrix([[2, 4], [6, 1]]) def test_fancy_index_matrix(): for M in (Matrix, SparseMatrix): a = M(3, 3, range(9)) assert a == a[:, :] assert a[1, :] == Matrix(1, 3, [3, 4, 5]) assert a[:, 1] == Matrix([1, 4, 7]) assert a[[0, 1], :] == Matrix([[0, 1, 2], [3, 4, 5]]) assert a[[0, 1], 2] == a[[0, 1], [2]] assert a[2, [0, 1]] == a[[2], [0, 1]] assert a[:, [0, 1]] == Matrix([[0, 1], [3, 4], [6, 7]]) assert a[0, 0] == 0 assert a[0:2, :] == Matrix([[0, 1, 2], [3, 4, 5]]) assert a[:, 0:2] == Matrix([[0, 1], [3, 4], [6, 7]]) assert a[::2, 1] == a[[0, 2], 1] assert a[1, ::2] == a[1, [0, 2]] a = M(3, 3, range(9)) assert a[[0, 2, 1, 2, 1], :] == Matrix([ [0, 1, 2], [6, 7, 8], [3, 4, 5], [6, 7, 8], [3, 4, 5]]) assert a[:, [0,2,1,2,1]] == Matrix([ [0, 2, 1, 2, 1], [3, 5, 4, 5, 4], [6, 8, 7, 8, 7]]) a = SparseMatrix.zeros(3) a[1, 2] = 2 a[0, 1] = 3 a[2, 0] = 4 assert a.extract([1, 1], [2]) == Matrix([ [2], [2]]) assert a.extract([1, 0], [2, 2, 2]) == Matrix([ [2, 2, 2], [0, 0, 0]]) assert a.extract([1, 0, 1, 2], [2, 0, 1, 0]) == Matrix([ [2, 0, 0, 0], [0, 0, 3, 0], [2, 0, 0, 0], [0, 4, 0, 4]]) def test_multiplication(): a = Matrix(( (1, 2), (3, 1), (0, 6), )) b = Matrix(( (1, 2), (3, 0), )) c = a*b assert c[0, 0] == 7 assert c[0, 1] == 2 assert c[1, 0] == 6 assert c[1, 1] == 6 assert c[2, 0] == 18 assert c[2, 1] == 0 try: eval('c = a @ b') except SyntaxError: pass else: assert c[0, 0] == 7 assert c[0, 1] == 2 assert c[1, 0] == 6 assert c[1, 1] == 6 assert c[2, 0] == 18 assert c[2, 1] == 0 h = matrix_multiply_elementwise(a, c) assert h == a.multiply_elementwise(c) assert h[0, 0] == 7 assert h[0, 1] == 4 assert h[1, 0] == 18 assert h[1, 1] == 6 assert h[2, 0] == 0 assert h[2, 1] == 0 raises(ShapeError, lambda: matrix_multiply_elementwise(a, b)) c = b * Symbol("x") assert isinstance(c, Matrix) assert c[0, 0] == x assert c[0, 1] == 2*x assert c[1, 0] == 3*x assert c[1, 1] == 0 c2 = x * b assert c == c2 c = 5 * b assert isinstance(c, Matrix) assert c[0, 0] == 5 assert c[0, 1] == 2*5 assert c[1, 0] == 3*5 assert c[1, 1] == 0 try: eval('c = 5 @ b') except SyntaxError: pass else: assert isinstance(c, Matrix) assert c[0, 0] == 5 assert c[0, 1] == 2*5 assert c[1, 0] == 3*5 assert c[1, 1] == 0 def test_power(): raises(NonSquareMatrixError, lambda: Matrix((1, 2))**2) R = Rational A = Matrix([[2, 3], [4, 5]]) assert (A**-3)[:] == [R(-269)/8, R(153)/8, R(51)/2, R(-29)/2] assert (A**5)[:] == [6140, 8097, 10796, 14237] A = Matrix([[2, 1, 3], [4, 2, 4], [6, 12, 1]]) assert (A**3)[:] == [290, 262, 251, 448, 440, 368, 702, 954, 433] assert A**0 == eye(3) assert A**1 == A assert (Matrix([[2]]) ** 100)[0, 0] == 2**100 assert eye(2)**10000000 == eye(2) assert Matrix([[1, 2], [3, 4]])**Integer(2) == Matrix([[7, 10], [15, 22]]) A = Matrix([[33, 24], [48, 57]]) assert (A**(S(1)/2))[:] == [5, 2, 4, 7] A = Matrix([[0, 4], [-1, 5]]) assert (A**(S(1)/2))**2 == A assert Matrix([[1, 0], [1, 1]])**(S(1)/2) == Matrix([[1, 0], [S.Half, 1]]) assert Matrix([[1, 0], [1, 1]])**0.5 == Matrix([[1.0, 0], [0.5, 1.0]]) from sympy.abc import a, b, n assert Matrix([[1, a], [0, 1]])**n == Matrix([[1, a*n], [0, 1]]) assert Matrix([[b, a], [0, b]])**n == Matrix([[b**n, a*b**(n-1)*n], [0, b**n]]) assert Matrix([[a, 1, 0], [0, a, 1], [0, 0, a]])**n == Matrix([ [a**n, a**(n-1)*n, a**(n-2)*(n-1)*n/2], [0, a**n, a**(n-1)*n], [0, 0, a**n]]) assert Matrix([[a, 1, 0], [0, a, 0], [0, 0, b]])**n == Matrix([ [a**n, a**(n-1)*n, 0], [0, a**n, 0], [0, 0, b**n]]) A = Matrix([[1, 0], [1, 7]]) assert A._matrix_pow_by_jordan_blocks(3) == A._eval_pow_by_recursion(3) A = Matrix([[2]]) assert A**10 == Matrix([[2**10]]) == A._matrix_pow_by_jordan_blocks(10) == \ A._eval_pow_by_recursion(10) # testing a matrix that cannot be jordan blocked issue 11766 m = Matrix([[3, 0, 0, 0, -3], [0, -3, -3, 0, 3], [0, 3, 0, 3, 0], [0, 0, 3, 0, 3], [3, 0, 0, 3, 0]]) raises(MatrixError, lambda: m._matrix_pow_by_jordan_blocks(10)) # test issue 11964 raises(ValueError, lambda: Matrix([[1, 1], [3, 3]])._matrix_pow_by_jordan_blocks(-10)) A = Matrix([[0, 1, 0], [0, 0, 1], [0, 0, 0]]) # Nilpotent jordan block size 3 assert A**10.0 == Matrix([[0, 0, 0], [0, 0, 0], [0, 0, 0]]) raises(ValueError, lambda: A**2.1) raises(ValueError, lambda: A**(S(3)/2)) A = Matrix([[8, 1], [3, 2]]) assert A**10.0 == Matrix([[1760744107, 272388050], [817164150, 126415807]]) A = Matrix([[0, 0, 1], [0, 0, 1], [0, 0, 1]]) # Nilpotent jordan block size 1 assert A**10.2 == Matrix([[0, 0, 1], [0, 0, 1], [0, 0, 1]]) A = Matrix([[0, 1, 0], [0, 0, 1], [0, 0, 1]]) # Nilpotent jordan block size 2 assert A**10.0 == Matrix([[0, 0, 1], [0, 0, 1], [0, 0, 1]]) n = Symbol('n', integer=True) raises(ValueError, lambda: A**n) n = Symbol('n', integer=True, nonnegative=True) raises(ValueError, lambda: A**n) assert A**(n + 2) == Matrix([[0, 0, 1], [0, 0, 1], [0, 0, 1]]) raises(ValueError, lambda: A**(S(3)/2)) A = Matrix([[0, 0, 1], [3, 0, 1], [4, 3, 1]]) assert A**5.0 == Matrix([[168, 72, 89], [291, 144, 161], [572, 267, 329]]) assert A**5.0 == A**5 def test_creation(): raises(ValueError, lambda: Matrix(5, 5, range(20))) raises(ValueError, lambda: Matrix(5, -1, [])) raises(IndexError, lambda: Matrix((1, 2))[2]) with raises(IndexError): Matrix((1, 2))[1:2] = 5 with raises(IndexError): Matrix((1, 2))[3] = 5 assert Matrix() == Matrix([]) == Matrix([[]]) == Matrix(0, 0, []) a = Matrix([[x, 0], [0, 0]]) m = a assert m.cols == m.rows assert m.cols == 2 assert m[:] == [x, 0, 0, 0] b = Matrix(2, 2, [x, 0, 0, 0]) m = b assert m.cols == m.rows assert m.cols == 2 assert m[:] == [x, 0, 0, 0] assert a == b assert Matrix(b) == b c = Matrix(( Matrix(( (1, 2, 3), (4, 5, 6) )), (7, 8, 9) )) assert c.cols == 3 assert c.rows == 3 assert c[:] == [1, 2, 3, 4, 5, 6, 7, 8, 9] assert Matrix(eye(2)) == eye(2) assert ImmutableMatrix(ImmutableMatrix(eye(2))) == ImmutableMatrix(eye(2)) assert ImmutableMatrix(c) == c.as_immutable() assert Matrix(ImmutableMatrix(c)) == ImmutableMatrix(c).as_mutable() assert c is not Matrix(c) def test_tolist(): lst = [[S.One, S.Half, x*y, S.Zero], [x, y, z, x**2], [y, -S.One, z*x, 3]] m = Matrix(lst) assert m.tolist() == lst def test_as_mutable(): assert zeros(0, 3).as_mutable() == zeros(0, 3) assert zeros(0, 3).as_immutable() == ImmutableMatrix(zeros(0, 3)) assert zeros(3, 0).as_immutable() == ImmutableMatrix(zeros(3, 0)) def test_determinant(): for M in [Matrix(), Matrix([[1]])]: assert ( M.det() == M._eval_det_bareiss() == M._eval_det_berkowitz() == M._eval_det_lu() == 1) M = Matrix(( (-3, 2), ( 8, -5) )) assert M.det(method="bareiss") == -1 assert M.det(method="berkowitz") == -1 assert M.det(method="lu") == -1 M = Matrix(( (x, 1), (y, 2*y) )) assert M.det(method="bareiss") == 2*x*y - y assert M.det(method="berkowitz") == 2*x*y - y assert M.det(method="lu") == 2*x*y - y M = Matrix(( (1, 1, 1), (1, 2, 3), (1, 3, 6) )) assert M.det(method="bareiss") == 1 assert M.det(method="berkowitz") == 1 assert M.det(method="lu") == 1 M = Matrix(( ( 3, -2, 0, 5), (-2, 1, -2, 2), ( 0, -2, 5, 0), ( 5, 0, 3, 4) )) assert M.det(method="bareiss") == -289 assert M.det(method="berkowitz") == -289 assert M.det(method="lu") == -289 M = Matrix(( ( 1, 2, 3, 4), ( 5, 6, 7, 8), ( 9, 10, 11, 12), (13, 14, 15, 16) )) assert M.det(method="bareiss") == 0 assert M.det(method="berkowitz") == 0 assert M.det(method="lu") == 0 M = Matrix(( (3, 2, 0, 0, 0), (0, 3, 2, 0, 0), (0, 0, 3, 2, 0), (0, 0, 0, 3, 2), (2, 0, 0, 0, 3) )) assert M.det(method="bareiss") == 275 assert M.det(method="berkowitz") == 275 assert M.det(method="lu") == 275 M = Matrix(( (1, 0, 1, 2, 12), (2, 0, 1, 1, 4), (2, 1, 1, -1, 3), (3, 2, -1, 1, 8), (1, 1, 1, 0, 6) )) assert M.det(method="bareiss") == -55 assert M.det(method="berkowitz") == -55 assert M.det(method="lu") == -55 M = Matrix(( (-5, 2, 3, 4, 5), ( 1, -4, 3, 4, 5), ( 1, 2, -3, 4, 5), ( 1, 2, 3, -2, 5), ( 1, 2, 3, 4, -1) )) assert M.det(method="bareiss") == 11664 assert M.det(method="berkowitz") == 11664 assert M.det(method="lu") == 11664 M = Matrix(( ( 2, 7, -1, 3, 2), ( 0, 0, 1, 0, 1), (-2, 0, 7, 0, 2), (-3, -2, 4, 5, 3), ( 1, 0, 0, 0, 1) )) assert M.det(method="bareiss") == 123 assert M.det(method="berkowitz") == 123 assert M.det(method="lu") == 123 M = Matrix(( (x, y, z), (1, 0, 0), (y, z, x) )) assert M.det(method="bareiss") == z**2 - x*y assert M.det(method="berkowitz") == z**2 - x*y assert M.det(method="lu") == z**2 - x*y # issue 13835 a = symbols('a') M = lambda n: Matrix([[i + a*j for i in range(n)] for j in range(n)]) assert M(5).det() == 0 assert M(6).det() == 0 assert M(7).det() == 0 def test_slicing(): m0 = eye(4) assert m0[:3, :3] == eye(3) assert m0[2:4, 0:2] == zeros(2) m1 = Matrix(3, 3, lambda i, j: i + j) assert m1[0, :] == Matrix(1, 3, (0, 1, 2)) assert m1[1:3, 1] == Matrix(2, 1, (2, 3)) m2 = Matrix([[0, 1, 2, 3], [4, 5, 6, 7], [8, 9, 10, 11], [12, 13, 14, 15]]) assert m2[:, -1] == Matrix(4, 1, [3, 7, 11, 15]) assert m2[-2:, :] == Matrix([[8, 9, 10, 11], [12, 13, 14, 15]]) def test_submatrix_assignment(): m = zeros(4) m[2:4, 2:4] = eye(2) assert m == Matrix(((0, 0, 0, 0), (0, 0, 0, 0), (0, 0, 1, 0), (0, 0, 0, 1))) m[:2, :2] = eye(2) assert m == eye(4) m[:, 0] = Matrix(4, 1, (1, 2, 3, 4)) assert m == Matrix(((1, 0, 0, 0), (2, 1, 0, 0), (3, 0, 1, 0), (4, 0, 0, 1))) m[:, :] = zeros(4) assert m == zeros(4) m[:, :] = [(1, 2, 3, 4), (5, 6, 7, 8), (9, 10, 11, 12), (13, 14, 15, 16)] assert m == Matrix(((1, 2, 3, 4), (5, 6, 7, 8), (9, 10, 11, 12), (13, 14, 15, 16))) m[:2, 0] = [0, 0] assert m == Matrix(((0, 2, 3, 4), (0, 6, 7, 8), (9, 10, 11, 12), (13, 14, 15, 16))) def test_extract(): m = Matrix(4, 3, lambda i, j: i*3 + j) assert m.extract([0, 1, 3], [0, 1]) == Matrix(3, 2, [0, 1, 3, 4, 9, 10]) assert m.extract([0, 3], [0, 0, 2]) == Matrix(2, 3, [0, 0, 2, 9, 9, 11]) assert m.extract(range(4), range(3)) == m raises(IndexError, lambda: m.extract([4], [0])) raises(IndexError, lambda: m.extract([0], [3])) def test_reshape(): m0 = eye(3) assert m0.reshape(1, 9) == Matrix(1, 9, (1, 0, 0, 0, 1, 0, 0, 0, 1)) m1 = Matrix(3, 4, lambda i, j: i + j) assert m1.reshape( 4, 3) == Matrix(((0, 1, 2), (3, 1, 2), (3, 4, 2), (3, 4, 5))) assert m1.reshape(2, 6) == Matrix(((0, 1, 2, 3, 1, 2), (3, 4, 2, 3, 4, 5))) def test_applyfunc(): m0 = eye(3) assert m0.applyfunc(lambda x: 2*x) == eye(3)*2 assert m0.applyfunc(lambda x: 0) == zeros(3) def test_expand(): m0 = Matrix([[x*(x + y), 2], [((x + y)*y)*x, x*(y + x*(x + y))]]) # Test if expand() returns a matrix m1 = m0.expand() assert m1 == Matrix( [[x*y + x**2, 2], [x*y**2 + y*x**2, x*y + y*x**2 + x**3]]) a = Symbol('a', real=True) assert Matrix([exp(I*a)]).expand(complex=True) == \ Matrix([cos(a) + I*sin(a)]) assert Matrix([[0, 1, 2], [0, 0, -1], [0, 0, 0]]).exp() == Matrix([ [1, 1, Rational(3, 2)], [0, 1, -1], [0, 0, 1]] ) def test_refine(): m0 = Matrix([[Abs(x)**2, sqrt(x**2)], [sqrt(x**2)*Abs(y)**2, sqrt(y**2)*Abs(x)**2]]) m1 = m0.refine(Q.real(x) & Q.real(y)) assert m1 == Matrix([[x**2, Abs(x)], [y**2*Abs(x), x**2*Abs(y)]]) m1 = m0.refine(Q.positive(x) & Q.positive(y)) assert m1 == Matrix([[x**2, x], [x*y**2, x**2*y]]) m1 = m0.refine(Q.negative(x) & Q.negative(y)) assert m1 == Matrix([[x**2, -x], [-x*y**2, -x**2*y]]) def test_random(): M = randMatrix(3, 3) M = randMatrix(3, 3, seed=3) assert M == randMatrix(3, 3, seed=3) M = randMatrix(3, 4, 0, 150) M = randMatrix(3, seed=4, symmetric=True) assert M == randMatrix(3, seed=4, symmetric=True) S = M.copy() S.simplify() assert S == M # doesn't fail when elements are Numbers, not int rng = random.Random(4) assert M == randMatrix(3, symmetric=True, prng=rng) # Ensure symmetry for size in (10, 11): # Test odd and even for percent in (100, 70, 30): M = randMatrix(size, symmetric=True, percent=percent, prng=rng) assert M == M.T M = randMatrix(10, min=1, percent=70) zero_count = 0 for i in range(M.shape[0]): for j in range(M.shape[1]): if M[i, j] == 0: zero_count += 1 assert zero_count == 30 def test_LUdecomp(): testmat = Matrix([[0, 2, 5, 3], [3, 3, 7, 4], [8, 4, 0, 2], [-2, 6, 3, 4]]) L, U, p = testmat.LUdecomposition() assert L.is_lower assert U.is_upper assert (L*U).permute_rows(p, 'backward') - testmat == zeros(4) testmat = Matrix([[6, -2, 7, 4], [0, 3, 6, 7], [1, -2, 7, 4], [-9, 2, 6, 3]]) L, U, p = testmat.LUdecomposition() assert L.is_lower assert U.is_upper assert (L*U).permute_rows(p, 'backward') - testmat == zeros(4) # non-square testmat = Matrix([[1, 2, 3], [4, 5, 6], [7, 8, 9], [10, 11, 12]]) L, U, p = testmat.LUdecomposition(rankcheck=False) assert L.is_lower assert U.is_upper assert (L*U).permute_rows(p, 'backward') - testmat == zeros(4, 3) # square and singular testmat = Matrix([[1, 2, 3], [2, 4, 6], [4, 5, 6]]) L, U, p = testmat.LUdecomposition(rankcheck=False) assert L.is_lower assert U.is_upper assert (L*U).permute_rows(p, 'backward') - testmat == zeros(3) M = Matrix(((1, x, 1), (2, y, 0), (y, 0, z))) L, U, p = M.LUdecomposition() assert L.is_lower assert U.is_upper assert (L*U).permute_rows(p, 'backward') - M == zeros(3) mL = Matrix(( (1, 0, 0), (2, 3, 0), )) assert mL.is_lower is True assert mL.is_upper is False mU = Matrix(( (1, 2, 3), (0, 4, 5), )) assert mU.is_lower is False assert mU.is_upper is True # test FF LUdecomp M = Matrix([[1, 3, 3], [3, 2, 6], [3, 2, 2]]) P, L, Dee, U = M.LUdecompositionFF() assert P*M == L*Dee.inv()*U M = Matrix([[1, 2, 3, 4], [3, -1, 2, 3], [3, 1, 3, -2], [6, -1, 0, 2]]) P, L, Dee, U = M.LUdecompositionFF() assert P*M == L*Dee.inv()*U M = Matrix([[0, 0, 1], [2, 3, 0], [3, 1, 4]]) P, L, Dee, U = M.LUdecompositionFF() assert P*M == L*Dee.inv()*U def test_LUsolve(): A = Matrix([[2, 3, 5], [3, 6, 2], [8, 3, 6]]) x = Matrix(3, 1, [3, 7, 5]) b = A*x soln = A.LUsolve(b) assert soln == x A = Matrix([[0, -1, 2], [5, 10, 7], [8, 3, 4]]) x = Matrix(3, 1, [-1, 2, 5]) b = A*x soln = A.LUsolve(b) assert soln == x A = Matrix([[2, 1], [1, 0], [1, 0]]) # issue 14548 b = Matrix([3, 1, 1]) assert A.LUsolve(b) == Matrix([1, 1]) b = Matrix([3, 1, 2]) # inconsistent raises(ValueError, lambda: A.LUsolve(b)) A = Matrix([[0, -1, 2], [5, 10, 7], [8, 3, 4], [2, 3, 5], [3, 6, 2], [8, 3, 6]]) x = Matrix([2, 1, -4]) b = A*x soln = A.LUsolve(b) assert soln == x A = Matrix([[0, -1, 2], [5, 10, 7]]) # underdetermined x = Matrix([-1, 2, 0]) b = A*x raises(NotImplementedError, lambda: A.LUsolve(b)) def test_QRsolve(): A = Matrix([[2, 3, 5], [3, 6, 2], [8, 3, 6]]) x = Matrix(3, 1, [3, 7, 5]) b = A*x soln = A.QRsolve(b) assert soln == x x = Matrix([[1, 2], [3, 4], [5, 6]]) b = A*x soln = A.QRsolve(b) assert soln == x A = Matrix([[0, -1, 2], [5, 10, 7], [8, 3, 4]]) x = Matrix(3, 1, [-1, 2, 5]) b = A*x soln = A.QRsolve(b) assert soln == x x = Matrix([[7, 8], [9, 10], [11, 12]]) b = A*x soln = A.QRsolve(b) assert soln == x def test_inverse(): A = eye(4) assert A.inv() == eye(4) assert A.inv(method="LU") == eye(4) assert A.inv(method="ADJ") == eye(4) A = Matrix([[2, 3, 5], [3, 6, 2], [8, 3, 6]]) Ainv = A.inv() assert A*Ainv == eye(3) assert A.inv(method="LU") == Ainv assert A.inv(method="ADJ") == Ainv # test that immutability is not a problem cls = ImmutableMatrix m = cls([[48, 49, 31], [ 9, 71, 94], [59, 28, 65]]) assert all(type(m.inv(s)) is cls for s in 'GE ADJ LU'.split()) cls = ImmutableSparseMatrix m = cls([[48, 49, 31], [ 9, 71, 94], [59, 28, 65]]) assert all(type(m.inv(s)) is cls for s in 'CH LDL'.split()) def test_matrix_inverse_mod(): A = Matrix(2, 1, [1, 0]) raises(NonSquareMatrixError, lambda: A.inv_mod(2)) A = Matrix(2, 2, [1, 0, 0, 0]) raises(ValueError, lambda: A.inv_mod(2)) A = Matrix(2, 2, [1, 2, 3, 4]) Ai = Matrix(2, 2, [1, 1, 0, 1]) assert A.inv_mod(3) == Ai A = Matrix(2, 2, [1, 0, 0, 1]) assert A.inv_mod(2) == A A = Matrix(3, 3, [1, 2, 3, 4, 5, 6, 7, 8, 9]) raises(ValueError, lambda: A.inv_mod(5)) A = Matrix(3, 3, [5, 1, 3, 2, 6, 0, 2, 1, 1]) Ai = Matrix(3, 3, [6, 8, 0, 1, 5, 6, 5, 6, 4]) assert A.inv_mod(9) == Ai A = Matrix(3, 3, [1, 6, -3, 4, 1, -5, 3, -5, 5]) Ai = Matrix(3, 3, [4, 3, 3, 1, 2, 5, 1, 5, 1]) assert A.inv_mod(6) == Ai A = Matrix(3, 3, [1, 6, 1, 4, 1, 5, 3, 2, 5]) Ai = Matrix(3, 3, [6, 0, 3, 6, 6, 4, 1, 6, 1]) assert A.inv_mod(7) == Ai def test_util(): R = Rational v1 = Matrix(1, 3, [1, 2, 3]) v2 = Matrix(1, 3, [3, 4, 5]) assert v1.norm() == sqrt(14) assert v1.project(v2) == Matrix(1, 3, [R(39)/25, R(52)/25, R(13)/5]) assert Matrix.zeros(1, 2) == Matrix(1, 2, [0, 0]) assert ones(1, 2) == Matrix(1, 2, [1, 1]) assert v1.copy() == v1 # cofactor assert eye(3) == eye(3).cofactor_matrix() test = Matrix([[1, 3, 2], [2, 6, 3], [2, 3, 6]]) assert test.cofactor_matrix() == \ Matrix([[27, -6, -6], [-12, 2, 3], [-3, 1, 0]]) test = Matrix([[1, 2, 3], [4, 5, 6], [7, 8, 9]]) assert test.cofactor_matrix() == \ Matrix([[-3, 6, -3], [6, -12, 6], [-3, 6, -3]]) def test_jacobian_hessian(): L = Matrix(1, 2, [x**2*y, 2*y**2 + x*y]) syms = [x, y] assert L.jacobian(syms) == Matrix([[2*x*y, x**2], [y, 4*y + x]]) L = Matrix(1, 2, [x, x**2*y**3]) assert L.jacobian(syms) == Matrix([[1, 0], [2*x*y**3, x**2*3*y**2]]) f = x**2*y syms = [x, y] assert hessian(f, syms) == Matrix([[2*y, 2*x], [2*x, 0]]) f = x**2*y**3 assert hessian(f, syms) == \ Matrix([[2*y**3, 6*x*y**2], [6*x*y**2, 6*x**2*y]]) f = z + x*y**2 g = x**2 + 2*y**3 ans = Matrix([[0, 2*y], [2*y, 2*x]]) assert ans == hessian(f, Matrix([x, y])) assert ans == hessian(f, Matrix([x, y]).T) assert hessian(f, (y, x), [g]) == Matrix([ [ 0, 6*y**2, 2*x], [6*y**2, 2*x, 2*y], [ 2*x, 2*y, 0]]) def test_QR(): A = Matrix([[1, 2], [2, 3]]) Q, S = A.QRdecomposition() R = Rational assert Q == Matrix([ [ 5**R(-1, 2), (R(2)/5)*(R(1)/5)**R(-1, 2)], [2*5**R(-1, 2), (-R(1)/5)*(R(1)/5)**R(-1, 2)]]) assert S == Matrix([[5**R(1, 2), 8*5**R(-1, 2)], [0, (R(1)/5)**R(1, 2)]]) assert Q*S == A assert Q.T * Q == eye(2) A = Matrix([[1, 1, 1], [1, 1, 3], [2, 3, 4]]) Q, R = A.QRdecomposition() assert Q.T * Q == eye(Q.cols) assert R.is_upper assert A == Q*R def test_QR_non_square(): # Narrow (cols < rows) matrices A = Matrix([[9, 0, 26], [12, 0, -7], [0, 4, 4], [0, -3, -3]]) Q, R = A.QRdecomposition() assert Q.T * Q == eye(Q.cols) assert R.is_upper assert A == Q*R A = Matrix([[1, -1, 4], [1, 4, -2], [1, 4, 2], [1, -1, 0]]) Q, R = A.QRdecomposition() assert Q.T * Q == eye(Q.cols) assert R.is_upper assert A == Q*R A = Matrix(2, 1, [1, 2]) Q, R = A.QRdecomposition() assert Q.T * Q == eye(Q.cols) assert R.is_upper assert A == Q*R # Wide (cols > rows) matrices A = Matrix([[1, 2, 3], [4, 5, 6]]) Q, R = A.QRdecomposition() assert Q.T * Q == eye(Q.cols) assert R.is_upper assert A == Q*R A = Matrix([[1, 2, 3, 4], [1, 4, 9, 16], [1, 8, 27, 64]]) Q, R = A.QRdecomposition() assert Q.T * Q == eye(Q.cols) assert R.is_upper assert A == Q*R A = Matrix(1, 2, [1, 2]) Q, R = A.QRdecomposition() assert Q.T * Q == eye(Q.cols) assert R.is_upper assert A == Q*R def test_QR_trivial(): # Rank deficient matrices A = Matrix([[1, 2, 3], [4, 5, 6], [7, 8, 9]]) Q, R = A.QRdecomposition() assert Q.T * Q == eye(Q.cols) assert R.is_upper assert A == Q*R A = Matrix([[1, 1, 1], [2, 2, 2], [3, 3, 3], [4, 4, 4]]) Q, R = A.QRdecomposition() assert Q.T * Q == eye(Q.cols) assert R.is_upper assert A == Q*R A = Matrix([[1, 1, 1], [2, 2, 2], [3, 3, 3], [4, 4, 4]]).T Q, R = A.QRdecomposition() assert Q.T * Q == eye(Q.cols) assert R.is_upper assert A == Q*R # Zero rank matrices A = Matrix([[0, 0, 0]]) Q, R = A.QRdecomposition() assert Q.T * Q == eye(Q.cols) assert R.is_upper assert A == Q*R A = Matrix([[0, 0, 0]]).T Q, R = A.QRdecomposition() assert Q.T * Q == eye(Q.cols) assert R.is_upper assert A == Q*R A = Matrix([[0, 0, 0], [0, 0, 0]]) Q, R = A.QRdecomposition() assert Q.T * Q == eye(Q.cols) assert R.is_upper assert A == Q*R A = Matrix([[0, 0, 0], [0, 0, 0]]).T Q, R = A.QRdecomposition() assert Q.T * Q == eye(Q.cols) assert R.is_upper assert A == Q*R # Rank deficient matrices with zero norm from beginning columns A = Matrix([[0, 0, 0], [1, 2, 3]]).T Q, R = A.QRdecomposition() assert Q.T * Q == eye(Q.cols) assert R.is_upper assert A == Q*R A = Matrix([[0, 0, 0, 0], [1, 2, 3, 4], [0, 0, 0, 0]]).T Q, R = A.QRdecomposition() assert Q.T * Q == eye(Q.cols) assert R.is_upper assert A == Q*R A = Matrix([[0, 0, 0, 0], [1, 2, 3, 4], [0, 0, 0, 0], [2, 4, 6, 8]]).T Q, R = A.QRdecomposition() assert Q.T * Q == eye(Q.cols) assert R.is_upper assert A == Q*R A = Matrix([[0, 0, 0], [0, 0, 0], [0, 0, 0], [1, 2, 3]]).T Q, R = A.QRdecomposition() assert Q.T * Q == eye(Q.cols) assert R.is_upper assert A == Q*R def test_nullspace(): # first test reduced row-ech form R = Rational M = Matrix([[5, 7, 2, 1], [1, 6, 2, -1]]) out, tmp = M.rref() assert out == Matrix([[1, 0, -R(2)/23, R(13)/23], [0, 1, R(8)/23, R(-6)/23]]) M = Matrix([[-5, -1, 4, -3, -1], [ 1, -1, -1, 1, 0], [-1, 0, 0, 0, 0], [ 4, 1, -4, 3, 1], [-2, 0, 2, -2, -1]]) assert M*M.nullspace()[0] == Matrix(5, 1, [0]*5) M = Matrix([[ 1, 3, 0, 2, 6, 3, 1], [-2, -6, 0, -2, -8, 3, 1], [ 3, 9, 0, 0, 6, 6, 2], [-1, -3, 0, 1, 0, 9, 3]]) out, tmp = M.rref() assert out == Matrix([[1, 3, 0, 0, 2, 0, 0], [0, 0, 0, 1, 2, 0, 0], [0, 0, 0, 0, 0, 1, R(1)/3], [0, 0, 0, 0, 0, 0, 0]]) # now check the vectors basis = M.nullspace() assert basis[0] == Matrix([-3, 1, 0, 0, 0, 0, 0]) assert basis[1] == Matrix([0, 0, 1, 0, 0, 0, 0]) assert basis[2] == Matrix([-2, 0, 0, -2, 1, 0, 0]) assert basis[3] == Matrix([0, 0, 0, 0, 0, R(-1)/3, 1]) # issue 4797; just see that we can do it when rows > cols M = Matrix([[1, 2], [2, 4], [3, 6]]) assert M.nullspace() def test_columnspace(): M = Matrix([[ 1, 2, 0, 2, 5], [-2, -5, 1, -1, -8], [ 0, -3, 3, 4, 1], [ 3, 6, 0, -7, 2]]) # now check the vectors basis = M.columnspace() assert basis[0] == Matrix([1, -2, 0, 3]) assert basis[1] == Matrix([2, -5, -3, 6]) assert basis[2] == Matrix([2, -1, 4, -7]) #check by columnspace definition a, b, c, d, e = symbols('a b c d e') X = Matrix([a, b, c, d, e]) for i in range(len(basis)): eq=M*X-basis[i] assert len(solve(eq, X)) != 0 #check if rank-nullity theorem holds assert M.rank() == len(basis) assert len(M.nullspace()) + len(M.columnspace()) == M.cols def test_wronskian(): assert wronskian([cos(x), sin(x)], x) == cos(x)**2 + sin(x)**2 assert wronskian([exp(x), exp(2*x)], x) == exp(3*x) assert wronskian([exp(x), x], x) == exp(x) - x*exp(x) assert wronskian([1, x, x**2], x) == 2 w1 = -6*exp(x)*sin(x)*x + 6*cos(x)*exp(x)*x**2 - 6*exp(x)*cos(x)*x - \ exp(x)*cos(x)*x**3 + exp(x)*sin(x)*x**3 assert wronskian([exp(x), cos(x), x**3], x).expand() == w1 assert wronskian([exp(x), cos(x), x**3], x, method='berkowitz').expand() \ == w1 w2 = -x**3*cos(x)**2 - x**3*sin(x)**2 - 6*x*cos(x)**2 - 6*x*sin(x)**2 assert wronskian([sin(x), cos(x), x**3], x).expand() == w2 assert wronskian([sin(x), cos(x), x**3], x, method='berkowitz').expand() \ == w2 assert wronskian([], x) == 1 def test_eigen(): R = Rational assert eye(3).charpoly(x) == Poly((x - 1)**3, x) assert eye(3).charpoly(y) == Poly((y - 1)**3, y) M = Matrix([[1, 0, 0], [0, 1, 0], [0, 0, 1]]) assert M.eigenvals(multiple=False) == {S.One: 3} assert M.eigenvals(multiple=True) == [1, 1, 1] assert M.eigenvects() == ( [(1, 3, [Matrix([1, 0, 0]), Matrix([0, 1, 0]), Matrix([0, 0, 1])])]) assert M.left_eigenvects() == ( [(1, 3, [Matrix([[1, 0, 0]]), Matrix([[0, 1, 0]]), Matrix([[0, 0, 1]])])]) M = Matrix([[0, 1, 1], [1, 0, 0], [1, 1, 1]]) assert M.eigenvals() == {2*S.One: 1, -S.One: 1, S.Zero: 1} assert M.eigenvects() == ( [ (-1, 1, [Matrix([-1, 1, 0])]), ( 0, 1, [Matrix([0, -1, 1])]), ( 2, 1, [Matrix([R(2, 3), R(1, 3), 1])]) ]) assert M.left_eigenvects() == ( [ (-1, 1, [Matrix([[-2, 1, 1]])]), (0, 1, [Matrix([[-1, -1, 1]])]), (2, 1, [Matrix([[1, 1, 1]])]) ]) a = Symbol('a') M = Matrix([[a, 0], [0, 1]]) assert M.eigenvals() == {a: 1, S.One: 1} M = Matrix([[1, -1], [1, 3]]) assert M.eigenvects() == ([(2, 2, [Matrix(2, 1, [-1, 1])])]) assert M.left_eigenvects() == ([(2, 2, [Matrix([[1, 1]])])]) M = Matrix([[1, 2, 3], [4, 5, 6], [7, 8, 9]]) a = R(15, 2) b = 3*33**R(1, 2) c = R(13, 2) d = (R(33, 8) + 3*b/8) e = (R(33, 8) - 3*b/8) def NS(e, n): return str(N(e, n)) r = [ (a - b/2, 1, [Matrix([(12 + 24/(c - b/2))/((c - b/2)*e) + 3/(c - b/2), (6 + 12/(c - b/2))/e, 1])]), ( 0, 1, [Matrix([1, -2, 1])]), (a + b/2, 1, [Matrix([(12 + 24/(c + b/2))/((c + b/2)*d) + 3/(c + b/2), (6 + 12/(c + b/2))/d, 1])]), ] r1 = [(NS(r[i][0], 2), NS(r[i][1], 2), [NS(j, 2) for j in r[i][2][0]]) for i in range(len(r))] r = M.eigenvects() r2 = [(NS(r[i][0], 2), NS(r[i][1], 2), [NS(j, 2) for j in r[i][2][0]]) for i in range(len(r))] assert sorted(r1) == sorted(r2) eps = Symbol('eps', real=True) M = Matrix([[abs(eps), I*eps ], [-I*eps, abs(eps) ]]) assert M.eigenvects() == ( [ ( 0, 1, [Matrix([[-I*eps/abs(eps)], [1]])]), ( 2*abs(eps), 1, [ Matrix([[I*eps/abs(eps)], [1]]) ] ), ]) assert M.left_eigenvects() == ( [ (0, 1, [Matrix([[I*eps/Abs(eps), 1]])]), (2*Abs(eps), 1, [Matrix([[-I*eps/Abs(eps), 1]])]) ]) M = Matrix(3, 3, [1, 2, 0, 0, 3, 0, 2, -4, 2]) M._eigenvects = M.eigenvects(simplify=False) assert max(i.q for i in M._eigenvects[0][2][0]) > 1 M._eigenvects = M.eigenvects(simplify=True) assert max(i.q for i in M._eigenvects[0][2][0]) == 1 M = Matrix([[S(1)/4, 1], [1, 1]]) assert M.eigenvects(simplify=True) == [ (S(5)/8 + sqrt(73)/8, 1, [Matrix([[-S(3)/8 + sqrt(73)/8], [1]])]), (-sqrt(73)/8 + S(5)/8, 1, [Matrix([[-sqrt(73)/8 - S(3)/8], [1]])])] assert M.eigenvects(simplify=False) ==[(S(5)/8 + sqrt(73)/8, 1, [Matrix([ [-1/(-sqrt(73)/8 - S(3)/8)], [ 1]])]), (-sqrt(73)/8 + S(5)/8, 1, [Matrix([ [-1/(-S(3)/8 + sqrt(73)/8)], [ 1]])])] m = Matrix([[1, .6, .6], [.6, .9, .9], [.9, .6, .6]]) evals = {-sqrt(385)/20 + S(5)/4: 1, sqrt(385)/20 + S(5)/4: 1, S.Zero: 1} assert m.eigenvals() == evals nevals = list(sorted(m.eigenvals(rational=False).keys())) sevals = list(sorted(evals.keys())) assert all(abs(nevals[i] - sevals[i]) < 1e-9 for i in range(len(nevals))) # issue 10719 assert Matrix([]).eigenvals() == {} assert Matrix([]).eigenvects() == [] # issue 15119 raises(NonSquareMatrixError, lambda : Matrix([[1, 2], [0, 4], [0, 0]]).eigenvals()) raises(NonSquareMatrixError, lambda : Matrix([[1, 0], [3, 4], [5, 6]]).eigenvals()) raises(NonSquareMatrixError, lambda : Matrix([[1, 2, 3], [0, 5, 6]]).eigenvals()) raises(NonSquareMatrixError, lambda : Matrix([[1, 0, 0], [4, 5, 0]]).eigenvals()) raises(NonSquareMatrixError, lambda : Matrix([[1, 2, 3], [0, 5, 6]]).eigenvals(error_when_incomplete = False)) raises(NonSquareMatrixError, lambda : Matrix([[1, 0, 0], [4, 5, 0]]).eigenvals(error_when_incomplete = False)) # issue 15125 from sympy.core.function import count_ops q = Symbol("q", positive = True) m = Matrix([[-2, exp(-q), 1], [exp(q), -2, 1], [1, 1, -2]]) assert count_ops(m.eigenvals(simplify=False)) > count_ops(m.eigenvals(simplify=True)) assert count_ops(m.eigenvals(simplify=lambda x: x)) > count_ops(m.eigenvals(simplify=True)) assert isinstance(m.eigenvals(simplify=True, multiple=False), dict) assert isinstance(m.eigenvals(simplify=True, multiple=True), list) assert isinstance(m.eigenvals(simplify=lambda x: x, multiple=False), dict) assert isinstance(m.eigenvals(simplify=lambda x: x, multiple=True), list) def test_subs(): assert Matrix([[1, x], [x, 4]]).subs(x, 5) == Matrix([[1, 5], [5, 4]]) assert Matrix([[x, 2], [x + y, 4]]).subs([[x, -1], [y, -2]]) == \ Matrix([[-1, 2], [-3, 4]]) assert Matrix([[x, 2], [x + y, 4]]).subs([(x, -1), (y, -2)]) == \ Matrix([[-1, 2], [-3, 4]]) assert Matrix([[x, 2], [x + y, 4]]).subs({x: -1, y: -2}) == \ Matrix([[-1, 2], [-3, 4]]) assert Matrix([x*y]).subs({x: y - 1, y: x - 1}, simultaneous=True) == \ Matrix([(x - 1)*(y - 1)]) for cls in classes: assert Matrix([[2, 0], [0, 2]]) == cls.eye(2).subs(1, 2) def test_xreplace(): assert Matrix([[1, x], [x, 4]]).xreplace({x: 5}) == \ Matrix([[1, 5], [5, 4]]) assert Matrix([[x, 2], [x + y, 4]]).xreplace({x: -1, y: -2}) == \ Matrix([[-1, 2], [-3, 4]]) for cls in classes: assert Matrix([[2, 0], [0, 2]]) == cls.eye(2).xreplace({1: 2}) def test_simplify(): n = Symbol('n') f = Function('f') M = Matrix([[ 1/x + 1/y, (x + x*y) / x ], [ (f(x) + y*f(x))/f(x), 2 * (1/n - cos(n * pi)/n) / pi ]]) M.simplify() assert M == Matrix([[ (x + y)/(x * y), 1 + y ], [ 1 + y, 2*((1 - 1*cos(pi*n))/(pi*n)) ]]) eq = (1 + x)**2 M = Matrix([[eq]]) M.simplify() assert M == Matrix([[eq]]) M.simplify(ratio=oo) == M assert M == Matrix([[eq.simplify(ratio=oo)]]) def test_transpose(): M = Matrix([[1, 2, 3, 4, 5, 6, 7, 8, 9, 0], [1, 2, 3, 4, 5, 6, 7, 8, 9, 0]]) assert M.T == Matrix( [ [1, 1], [2, 2], [3, 3], [4, 4], [5, 5], [6, 6], [7, 7], [8, 8], [9, 9], [0, 0] ]) assert M.T.T == M assert M.T == M.transpose() def test_conjugate(): M = Matrix([[0, I, 5], [1, 2, 0]]) assert M.T == Matrix([[0, 1], [I, 2], [5, 0]]) assert M.C == Matrix([[0, -I, 5], [1, 2, 0]]) assert M.C == M.conjugate() assert M.H == M.T.C assert M.H == Matrix([[ 0, 1], [-I, 2], [ 5, 0]]) def test_conj_dirac(): raises(AttributeError, lambda: eye(3).D) M = Matrix([[1, I, I, I], [0, 1, I, I], [0, 0, 1, I], [0, 0, 0, 1]]) assert M.D == Matrix([[ 1, 0, 0, 0], [-I, 1, 0, 0], [-I, -I, -1, 0], [-I, -I, I, -1]]) def test_trace(): M = Matrix([[1, 0, 0], [0, 5, 0], [0, 0, 8]]) assert M.trace() == 14 def test_shape(): M = Matrix([[x, 0, 0], [0, y, 0]]) assert M.shape == (2, 3) def test_col_row_op(): M = Matrix([[x, 0, 0], [0, y, 0]]) M.row_op(1, lambda r, j: r + j + 1) assert M == Matrix([[x, 0, 0], [1, y + 2, 3]]) M.col_op(0, lambda c, j: c + y**j) assert M == Matrix([[x + 1, 0, 0], [1 + y, y + 2, 3]]) # neither row nor slice give copies that allow the original matrix to # be changed assert M.row(0) == Matrix([[x + 1, 0, 0]]) r1 = M.row(0) r1[0] = 42 assert M[0, 0] == x + 1 r1 = M[0, :-1] # also testing negative slice r1[0] = 42 assert M[0, 0] == x + 1 c1 = M.col(0) assert c1 == Matrix([x + 1, 1 + y]) c1[0] = 0 assert M[0, 0] == x + 1 c1 = M[:, 0] c1[0] = 42 assert M[0, 0] == x + 1 def test_zip_row_op(): for cls in classes[:2]: # XXX: immutable matrices don't support row ops M = cls.eye(3) M.zip_row_op(1, 0, lambda v, u: v + 2*u) assert M == cls([[1, 0, 0], [2, 1, 0], [0, 0, 1]]) M = cls.eye(3)*2 M[0, 1] = -1 M.zip_row_op(1, 0, lambda v, u: v + 2*u); M assert M == cls([[2, -1, 0], [4, 0, 0], [0, 0, 2]]) def test_issue_3950(): m = Matrix([1, 2, 3]) a = Matrix([1, 2, 3]) b = Matrix([2, 2, 3]) assert not (m in []) assert not (m in [1]) assert m != 1 assert m == a assert m != b def test_issue_3981(): class Index1(object): def __index__(self): return 1 class Index2(object): def __index__(self): return 2 index1 = Index1() index2 = Index2() m = Matrix([1, 2, 3]) assert m[index2] == 3 m[index2] = 5 assert m[2] == 5 m = Matrix([[1, 2, 3], [4, 5, 6]]) assert m[index1, index2] == 6 assert m[1, index2] == 6 assert m[index1, 2] == 6 m[index1, index2] = 4 assert m[1, 2] == 4 m[1, index2] = 6 assert m[1, 2] == 6 m[index1, 2] = 8 assert m[1, 2] == 8 def test_evalf(): a = Matrix([sqrt(5), 6]) assert all(a.evalf()[i] == a[i].evalf() for i in range(2)) assert all(a.evalf(2)[i] == a[i].evalf(2) for i in range(2)) assert all(a.n(2)[i] == a[i].n(2) for i in range(2)) def test_is_symbolic(): a = Matrix([[x, x], [x, x]]) assert a.is_symbolic() is True a = Matrix([[1, 2, 3, 4], [5, 6, 7, 8]]) assert a.is_symbolic() is False a = Matrix([[1, 2, 3, 4], [5, 6, x, 8]]) assert a.is_symbolic() is True a = Matrix([[1, x, 3]]) assert a.is_symbolic() is True a = Matrix([[1, 2, 3]]) assert a.is_symbolic() is False a = Matrix([[1], [x], [3]]) assert a.is_symbolic() is True a = Matrix([[1], [2], [3]]) assert a.is_symbolic() is False def test_is_upper(): a = Matrix([[1, 2, 3]]) assert a.is_upper is True a = Matrix([[1], [2], [3]]) assert a.is_upper is False a = zeros(4, 2) assert a.is_upper is True def test_is_lower(): a = Matrix([[1, 2, 3]]) assert a.is_lower is False a = Matrix([[1], [2], [3]]) assert a.is_lower is True def test_is_nilpotent(): a = Matrix(4, 4, [0, 2, 1, 6, 0, 0, 1, 2, 0, 0, 0, 3, 0, 0, 0, 0]) assert a.is_nilpotent() a = Matrix([[1, 0], [0, 1]]) assert not a.is_nilpotent() a = Matrix([]) assert a.is_nilpotent() def test_zeros_ones_fill(): n, m = 3, 5 a = zeros(n, m) a.fill( 5 ) b = 5 * ones(n, m) assert a == b assert a.rows == b.rows == 3 assert a.cols == b.cols == 5 assert a.shape == b.shape == (3, 5) assert zeros(2) == zeros(2, 2) assert ones(2) == ones(2, 2) assert zeros(2, 3) == Matrix(2, 3, [0]*6) assert ones(2, 3) == Matrix(2, 3, [1]*6) def test_empty_zeros(): a = zeros(0) assert a == Matrix() a = zeros(0, 2) assert a.rows == 0 assert a.cols == 2 a = zeros(2, 0) assert a.rows == 2 assert a.cols == 0 def test_issue_3749(): a = Matrix([[x**2, x*y], [x*sin(y), x*cos(y)]]) assert a.diff(x) == Matrix([[2*x, y], [sin(y), cos(y)]]) assert Matrix([ [x, -x, x**2], [exp(x), 1/x - exp(-x), x + 1/x]]).limit(x, oo) == \ Matrix([[oo, -oo, oo], [oo, 0, oo]]) assert Matrix([ [(exp(x) - 1)/x, 2*x + y*x, x**x ], [1/x, abs(x), abs(sin(x + 1))]]).limit(x, 0) == \ Matrix([[1, 0, 1], [oo, 0, sin(1)]]) assert a.integrate(x) == Matrix([ [Rational(1, 3)*x**3, y*x**2/2], [x**2*sin(y)/2, x**2*cos(y)/2]]) def test_inv_iszerofunc(): A = eye(4) A.col_swap(0, 1) for method in "GE", "LU": assert A.inv(method=method, iszerofunc=lambda x: x == 0) == \ A.inv(method="ADJ") def test_jacobian_metrics(): rho, phi = symbols("rho,phi") X = Matrix([rho*cos(phi), rho*sin(phi)]) Y = Matrix([rho, phi]) J = X.jacobian(Y) assert J == X.jacobian(Y.T) assert J == (X.T).jacobian(Y) assert J == (X.T).jacobian(Y.T) g = J.T*eye(J.shape[0])*J g = g.applyfunc(trigsimp) assert g == Matrix([[1, 0], [0, rho**2]]) def test_jacobian2(): rho, phi = symbols("rho,phi") X = Matrix([rho*cos(phi), rho*sin(phi), rho**2]) Y = Matrix([rho, phi]) J = Matrix([ [cos(phi), -rho*sin(phi)], [sin(phi), rho*cos(phi)], [ 2*rho, 0], ]) assert X.jacobian(Y) == J def test_issue_4564(): X = Matrix([exp(x + y + z), exp(x + y + z), exp(x + y + z)]) Y = Matrix([x, y, z]) for i in range(1, 3): for j in range(1, 3): X_slice = X[:i, :] Y_slice = Y[:j, :] J = X_slice.jacobian(Y_slice) assert J.rows == i assert J.cols == j for k in range(j): assert J[:, k] == X_slice def test_nonvectorJacobian(): X = Matrix([[exp(x + y + z), exp(x + y + z)], [exp(x + y + z), exp(x + y + z)]]) raises(TypeError, lambda: X.jacobian(Matrix([x, y, z]))) X = X[0, :] Y = Matrix([[x, y], [x, z]]) raises(TypeError, lambda: X.jacobian(Y)) raises(TypeError, lambda: X.jacobian(Matrix([ [x, y], [x, z] ]))) def test_vec(): m = Matrix([[1, 3], [2, 4]]) m_vec = m.vec() assert m_vec.cols == 1 for i in range(4): assert m_vec[i] == i + 1 def test_vech(): m = Matrix([[1, 2], [2, 3]]) m_vech = m.vech() assert m_vech.cols == 1 for i in range(3): assert m_vech[i] == i + 1 m_vech = m.vech(diagonal=False) assert m_vech[0] == 2 m = Matrix([[1, x*(x + y)], [y*x + x**2, 1]]) m_vech = m.vech(diagonal=False) assert m_vech[0] == x*(x + y) m = Matrix([[1, x*(x + y)], [y*x, 1]]) m_vech = m.vech(diagonal=False, check_symmetry=False) assert m_vech[0] == y*x def test_vech_errors(): m = Matrix([[1, 3]]) raises(ShapeError, lambda: m.vech()) m = Matrix([[1, 3], [2, 4]]) raises(ValueError, lambda: m.vech()) raises(ShapeError, lambda: Matrix([ [1, 3] ]).vech()) raises(ValueError, lambda: Matrix([ [1, 3], [2, 4] ]).vech()) def test_diag(): a = Matrix([[1, 2], [2, 3]]) b = Matrix([[3, x], [y, 3]]) c = Matrix([[3, x, 3], [y, 3, z], [x, y, z]]) assert diag(a, b, b) == Matrix([ [1, 2, 0, 0, 0, 0], [2, 3, 0, 0, 0, 0], [0, 0, 3, x, 0, 0], [0, 0, y, 3, 0, 0], [0, 0, 0, 0, 3, x], [0, 0, 0, 0, y, 3], ]) assert diag(a, b, c) == Matrix([ [1, 2, 0, 0, 0, 0, 0], [2, 3, 0, 0, 0, 0, 0], [0, 0, 3, x, 0, 0, 0], [0, 0, y, 3, 0, 0, 0], [0, 0, 0, 0, 3, x, 3], [0, 0, 0, 0, y, 3, z], [0, 0, 0, 0, x, y, z], ]) assert diag(a, c, b) == Matrix([ [1, 2, 0, 0, 0, 0, 0], [2, 3, 0, 0, 0, 0, 0], [0, 0, 3, x, 3, 0, 0], [0, 0, y, 3, z, 0, 0], [0, 0, x, y, z, 0, 0], [0, 0, 0, 0, 0, 3, x], [0, 0, 0, 0, 0, y, 3], ]) a = Matrix([x, y, z]) b = Matrix([[1, 2], [3, 4]]) c = Matrix([[5, 6]]) assert diag(a, 7, b, c) == Matrix([ [x, 0, 0, 0, 0, 0], [y, 0, 0, 0, 0, 0], [z, 0, 0, 0, 0, 0], [0, 7, 0, 0, 0, 0], [0, 0, 1, 2, 0, 0], [0, 0, 3, 4, 0, 0], [0, 0, 0, 0, 5, 6], ]) assert diag(1, [2, 3], [[4, 5]]) == Matrix([ [1, 0, 0, 0], [0, 2, 0, 0], [0, 3, 0, 0], [0, 0, 4, 5]]) def test_get_diag_blocks1(): a = Matrix([[1, 2], [2, 3]]) b = Matrix([[3, x], [y, 3]]) c = Matrix([[3, x, 3], [y, 3, z], [x, y, z]]) assert a.get_diag_blocks() == [a] assert b.get_diag_blocks() == [b] assert c.get_diag_blocks() == [c] def test_get_diag_blocks2(): a = Matrix([[1, 2], [2, 3]]) b = Matrix([[3, x], [y, 3]]) c = Matrix([[3, x, 3], [y, 3, z], [x, y, z]]) assert diag(a, b, b).get_diag_blocks() == [a, b, b] assert diag(a, b, c).get_diag_blocks() == [a, b, c] assert diag(a, c, b).get_diag_blocks() == [a, c, b] assert diag(c, c, b).get_diag_blocks() == [c, c, b] def test_inv_block(): a = Matrix([[1, 2], [2, 3]]) b = Matrix([[3, x], [y, 3]]) c = Matrix([[3, x, 3], [y, 3, z], [x, y, z]]) A = diag(a, b, b) assert A.inv(try_block_diag=True) == diag(a.inv(), b.inv(), b.inv()) A = diag(a, b, c) assert A.inv(try_block_diag=True) == diag(a.inv(), b.inv(), c.inv()) A = diag(a, c, b) assert A.inv(try_block_diag=True) == diag(a.inv(), c.inv(), b.inv()) A = diag(a, a, b, a, c, a) assert A.inv(try_block_diag=True) == diag( a.inv(), a.inv(), b.inv(), a.inv(), c.inv(), a.inv()) assert A.inv(try_block_diag=True, method="ADJ") == diag( a.inv(method="ADJ"), a.inv(method="ADJ"), b.inv(method="ADJ"), a.inv(method="ADJ"), c.inv(method="ADJ"), a.inv(method="ADJ")) def test_creation_args(): """ Check that matrix dimensions can be specified using any reasonable type (see issue 4614). """ raises(ValueError, lambda: zeros(3, -1)) raises(TypeError, lambda: zeros(1, 2, 3, 4)) assert zeros(long(3)) == zeros(3) assert zeros(Integer(3)) == zeros(3) assert zeros(3.) == zeros(3) assert eye(long(3)) == eye(3) assert eye(Integer(3)) == eye(3) assert eye(3.) == eye(3) assert ones(long(3), Integer(4)) == ones(3, 4) raises(TypeError, lambda: Matrix(5)) raises(TypeError, lambda: Matrix(1, 2)) def test_diagonal_symmetrical(): m = Matrix(2, 2, [0, 1, 1, 0]) assert not m.is_diagonal() assert m.is_symmetric() assert m.is_symmetric(simplify=False) m = Matrix(2, 2, [1, 0, 0, 1]) assert m.is_diagonal() m = diag(1, 2, 3) assert m.is_diagonal() assert m.is_symmetric() m = Matrix(3, 3, [1, 0, 0, 0, 2, 0, 0, 0, 3]) assert m == diag(1, 2, 3) m = Matrix(2, 3, zeros(2, 3)) assert not m.is_symmetric() assert m.is_diagonal() m = Matrix(((5, 0), (0, 6), (0, 0))) assert m.is_diagonal() m = Matrix(((5, 0, 0), (0, 6, 0))) assert m.is_diagonal() m = Matrix(3, 3, [1, x**2 + 2*x + 1, y, (x + 1)**2, 2, 0, y, 0, 3]) assert m.is_symmetric() assert not m.is_symmetric(simplify=False) assert m.expand().is_symmetric(simplify=False) def test_diagonalization(): m = Matrix(3, 2, [-3, 1, -3, 20, 3, 10]) assert not m.is_diagonalizable() assert not m.is_symmetric() raises(NonSquareMatrixError, lambda: m.diagonalize()) # diagonalizable m = diag(1, 2, 3) (P, D) = m.diagonalize() assert P == eye(3) assert D == m m = Matrix(2, 2, [0, 1, 1, 0]) assert m.is_symmetric() assert m.is_diagonalizable() (P, D) = m.diagonalize() assert P.inv() * m * P == D m = Matrix(2, 2, [1, 0, 0, 3]) assert m.is_symmetric() assert m.is_diagonalizable() (P, D) = m.diagonalize() assert P.inv() * m * P == D assert P == eye(2) assert D == m m = Matrix(2, 2, [1, 1, 0, 0]) assert m.is_diagonalizable() (P, D) = m.diagonalize() assert P.inv() * m * P == D m = Matrix(3, 3, [1, 2, 0, 0, 3, 0, 2, -4, 2]) assert m.is_diagonalizable() (P, D) = m.diagonalize() assert P.inv() * m * P == D for i in P: assert i.as_numer_denom()[1] == 1 m = Matrix(2, 2, [1, 0, 0, 0]) assert m.is_diagonal() assert m.is_diagonalizable() (P, D) = m.diagonalize() assert P.inv() * m * P == D assert P == Matrix([[0, 1], [1, 0]]) # diagonalizable, complex only m = Matrix(2, 2, [0, 1, -1, 0]) assert not m.is_diagonalizable(True) raises(MatrixError, lambda: m.diagonalize(True)) assert m.is_diagonalizable() (P, D) = m.diagonalize() assert P.inv() * m * P == D # not diagonalizable m = Matrix(2, 2, [0, 1, 0, 0]) assert not m.is_diagonalizable() raises(MatrixError, lambda: m.diagonalize()) m = Matrix(3, 3, [-3, 1, -3, 20, 3, 10, 2, -2, 4]) assert not m.is_diagonalizable() raises(MatrixError, lambda: m.diagonalize()) # symbolic a, b, c, d = symbols('a b c d') m = Matrix(2, 2, [a, c, c, b]) assert m.is_symmetric() assert m.is_diagonalizable() @XFAIL def test_eigen_vects(): m = Matrix(2, 2, [1, 0, 0, I]) raises(NotImplementedError, lambda: m.is_diagonalizable(True)) # !!! bug because of eigenvects() or roots(x**2 + (-1 - I)*x + I, x) # see issue 5292 assert not m.is_diagonalizable(True) raises(MatrixError, lambda: m.diagonalize(True)) (P, D) = m.diagonalize(True) def test_jordan_form(): m = Matrix(3, 2, [-3, 1, -3, 20, 3, 10]) raises(NonSquareMatrixError, lambda: m.jordan_form()) # diagonalizable m = Matrix(3, 3, [7, -12, 6, 10, -19, 10, 12, -24, 13]) Jmust = Matrix(3, 3, [-1, 0, 0, 0, 1, 0, 0, 0, 1]) P, J = m.jordan_form() assert Jmust == J assert Jmust == m.diagonalize()[1] # m = Matrix(3, 3, [0, 6, 3, 1, 3, 1, -2, 2, 1]) # m.jordan_form() # very long # m.jordan_form() # # diagonalizable, complex only # Jordan cells # complexity: one of eigenvalues is zero m = Matrix(3, 3, [0, 1, 0, -4, 4, 0, -2, 1, 2]) # The blocks are ordered according to the value of their eigenvalues, # in order to make the matrix compatible with .diagonalize() Jmust = Matrix(3, 3, [2, 1, 0, 0, 2, 0, 0, 0, 2]) P, J = m.jordan_form() assert Jmust == J # complexity: all of eigenvalues are equal m = Matrix(3, 3, [2, 6, -15, 1, 1, -5, 1, 2, -6]) # Jmust = Matrix(3, 3, [-1, 0, 0, 0, -1, 1, 0, 0, -1]) # same here see 1456ff Jmust = Matrix(3, 3, [-1, 1, 0, 0, -1, 0, 0, 0, -1]) P, J = m.jordan_form() assert Jmust == J # complexity: two of eigenvalues are zero m = Matrix(3, 3, [4, -5, 2, 5, -7, 3, 6, -9, 4]) Jmust = Matrix(3, 3, [0, 1, 0, 0, 0, 0, 0, 0, 1]) P, J = m.jordan_form() assert Jmust == J m = Matrix(4, 4, [6, 5, -2, -3, -3, -1, 3, 3, 2, 1, -2, -3, -1, 1, 5, 5]) Jmust = Matrix(4, 4, [2, 1, 0, 0, 0, 2, 0, 0, 0, 0, 2, 1, 0, 0, 0, 2] ) P, J = m.jordan_form() assert Jmust == J m = Matrix(4, 4, [6, 2, -8, -6, -3, 2, 9, 6, 2, -2, -8, -6, -1, 0, 3, 4]) # Jmust = Matrix(4, 4, [2, 0, 0, 0, 0, 2, 1, 0, 0, 0, 2, 0, 0, 0, 0, -2]) # same here see 1456ff Jmust = Matrix(4, 4, [-2, 0, 0, 0, 0, 2, 1, 0, 0, 0, 2, 0, 0, 0, 0, 2]) P, J = m.jordan_form() assert Jmust == J m = Matrix(4, 4, [5, 4, 2, 1, 0, 1, -1, -1, -1, -1, 3, 0, 1, 1, -1, 2]) assert not m.is_diagonalizable() Jmust = Matrix(4, 4, [1, 0, 0, 0, 0, 2, 0, 0, 0, 0, 4, 1, 0, 0, 0, 4]) P, J = m.jordan_form() assert Jmust == J # checking for maximum precision to remain unchanged m = Matrix([[Float('1.0', precision=110), Float('2.0', precision=110)], [Float('3.14159265358979323846264338327', precision=110), Float('4.0', precision=110)]]) P, J = m.jordan_form() for term in J._mat: if isinstance(term, Float): assert term._prec == 110 def test_jordan_form_complex_issue_9274(): A = Matrix([[ 2, 4, 1, 0], [-4, 2, 0, 1], [ 0, 0, 2, 4], [ 0, 0, -4, 2]]) p = 2 - 4*I; q = 2 + 4*I; Jmust1 = Matrix([[p, 1, 0, 0], [0, p, 0, 0], [0, 0, q, 1], [0, 0, 0, q]]) Jmust2 = Matrix([[q, 1, 0, 0], [0, q, 0, 0], [0, 0, p, 1], [0, 0, 0, p]]) P, J = A.jordan_form() assert J == Jmust1 or J == Jmust2 assert simplify(P*J*P.inv()) == A def test_issue_10220(): # two non-orthogonal Jordan blocks with eigenvalue 1 M = Matrix([[1, 0, 0, 1], [0, 1, 1, 0], [0, 0, 1, 1], [0, 0, 0, 1]]) P, J = M.jordan_form() assert P == Matrix([[0, 1, 0, 1], [1, 0, 0, 0], [0, 1, 0, 0], [0, 0, 1, 0]]) assert J == Matrix([ [1, 1, 0, 0], [0, 1, 1, 0], [0, 0, 1, 0], [0, 0, 0, 1]]) def test_Matrix_berkowitz_charpoly(): UA, K_i, K_w = symbols('UA K_i K_w') A = Matrix([[-K_i - UA + K_i**2/(K_i + K_w), K_i*K_w/(K_i + K_w)], [ K_i*K_w/(K_i + K_w), -K_w + K_w**2/(K_i + K_w)]]) charpoly = A.charpoly(x) assert charpoly == \ Poly(x**2 + (K_i*UA + K_w*UA + 2*K_i*K_w)/(K_i + K_w)*x + K_i*K_w*UA/(K_i + K_w), x, domain='ZZ(K_i,K_w,UA)') assert type(charpoly) is PurePoly A = Matrix([[1, 3], [2, 0]]) assert A.charpoly() == A.charpoly(x) == PurePoly(x**2 - x - 6) A = Matrix([[1, 2], [x, 0]]) p = A.charpoly(x) assert p.gen != x assert p.as_expr().subs(p.gen, x) == x**2 - 3*x def test_exp(): m = Matrix([[3, 4], [0, -2]]) m_exp = Matrix([[exp(3), -4*exp(-2)/5 + 4*exp(3)/5], [0, exp(-2)]]) assert m.exp() == m_exp assert exp(m) == m_exp m = Matrix([[1, 0], [0, 1]]) assert m.exp() == Matrix([[E, 0], [0, E]]) assert exp(m) == Matrix([[E, 0], [0, E]]) m = Matrix([[1, -1], [1, 1]]) assert m.exp() == Matrix([[E*cos(1), -E*sin(1)], [E*sin(1), E*cos(1)]]) def test_has(): A = Matrix(((x, y), (2, 3))) assert A.has(x) assert not A.has(z) assert A.has(Symbol) A = A.subs(x, 2) assert not A.has(x) def test_LUdecomposition_Simple_iszerofunc(): # Test if callable passed to matrices.LUdecomposition_Simple() as iszerofunc keyword argument is used inside # matrices.LUdecomposition_Simple() magic_string = "I got passed in!" def goofyiszero(value): raise ValueError(magic_string) try: lu, p = Matrix([[1, 0], [0, 1]]).LUdecomposition_Simple(iszerofunc=goofyiszero) except ValueError as err: assert magic_string == err.args[0] return assert False def test_LUdecomposition_iszerofunc(): # Test if callable passed to matrices.LUdecomposition() as iszerofunc keyword argument is used inside # matrices.LUdecomposition_Simple() magic_string = "I got passed in!" def goofyiszero(value): raise ValueError(magic_string) try: l, u, p = Matrix([[1, 0], [0, 1]]).LUdecomposition(iszerofunc=goofyiszero) except ValueError as err: assert magic_string == err.args[0] return assert False def test_find_reasonable_pivot_naive_finds_guaranteed_nonzero1(): # Test if matrices._find_reasonable_pivot_naive() # finds a guaranteed non-zero pivot when the # some of the candidate pivots are symbolic expressions. # Keyword argument: simpfunc=None indicates that no simplifications # should be performed during the search. x = Symbol('x') column = Matrix(3, 1, [x, cos(x)**2 + sin(x)**2, Rational(1, 2)]) pivot_offset, pivot_val, pivot_assumed_nonzero, simplified =\ _find_reasonable_pivot_naive(column) assert pivot_val == Rational(1, 2) def test_find_reasonable_pivot_naive_finds_guaranteed_nonzero2(): # Test if matrices._find_reasonable_pivot_naive() # finds a guaranteed non-zero pivot when the # some of the candidate pivots are symbolic expressions. # Keyword argument: simpfunc=_simplify indicates that the search # should attempt to simplify candidate pivots. x = Symbol('x') column = Matrix(3, 1, [x, cos(x)**2+sin(x)**2+x**2, cos(x)**2+sin(x)**2]) pivot_offset, pivot_val, pivot_assumed_nonzero, simplified =\ _find_reasonable_pivot_naive(column, simpfunc=_simplify) assert pivot_val == 1 def test_find_reasonable_pivot_naive_simplifies(): # Test if matrices._find_reasonable_pivot_naive() # simplifies candidate pivots, and reports # their offsets correctly. x = Symbol('x') column = Matrix(3, 1, [x, cos(x)**2+sin(x)**2+x, cos(x)**2+sin(x)**2]) pivot_offset, pivot_val, pivot_assumed_nonzero, simplified =\ _find_reasonable_pivot_naive(column, simpfunc=_simplify) assert len(simplified) == 2 assert simplified[0][0] == 1 assert simplified[0][1] == 1+x assert simplified[1][0] == 2 assert simplified[1][1] == 1 def test_errors(): raises(ValueError, lambda: Matrix([[1, 2], [1]])) raises(IndexError, lambda: Matrix([[1, 2]])[1.2, 5]) raises(IndexError, lambda: Matrix([[1, 2]])[1, 5.2]) raises(ValueError, lambda: randMatrix(3, c=4, symmetric=True)) raises(ValueError, lambda: Matrix([1, 2]).reshape(4, 6)) raises(ShapeError, lambda: Matrix([[1, 2], [3, 4]]).copyin_matrix([1, 0], Matrix([1, 2]))) raises(TypeError, lambda: Matrix([[1, 2], [3, 4]]).copyin_list([0, 1], set([]))) raises(NonSquareMatrixError, lambda: Matrix([[1, 2, 3], [2, 3, 0]]).inv()) raises(ShapeError, lambda: Matrix(1, 2, [1, 2]).row_join(Matrix([[1, 2], [3, 4]]))) raises( ShapeError, lambda: Matrix([1, 2]).col_join(Matrix([[1, 2], [3, 4]]))) raises(ShapeError, lambda: Matrix([1]).row_insert(1, Matrix([[1, 2], [3, 4]]))) raises(ShapeError, lambda: Matrix([1]).col_insert(1, Matrix([[1, 2], [3, 4]]))) raises(NonSquareMatrixError, lambda: Matrix([1, 2]).trace()) raises(TypeError, lambda: Matrix([1]).applyfunc(1)) raises(ShapeError, lambda: Matrix([1]).LUsolve(Matrix([[1, 2], [3, 4]]))) raises(ValueError, lambda: Matrix([[1, 2], [3, 4]]).minor(4, 5)) raises(ValueError, lambda: Matrix([[1, 2], [3, 4]]).minor_submatrix(4, 5)) raises(TypeError, lambda: Matrix([1, 2, 3]).cross(1)) raises(TypeError, lambda: Matrix([1, 2, 3]).dot(1)) raises(ShapeError, lambda: Matrix([1, 2, 3]).dot(Matrix([1, 2]))) raises(ShapeError, lambda: Matrix([1, 2]).dot([])) raises(TypeError, lambda: Matrix([1, 2]).dot('a')) with warns_deprecated_sympy(): Matrix([[1, 2], [3, 4]]).dot(Matrix([[4, 3], [1, 2]])) raises(ShapeError, lambda: Matrix([1, 2]).dot([1, 2, 3])) raises(NonSquareMatrixError, lambda: Matrix([1, 2, 3]).exp()) raises(ShapeError, lambda: Matrix([[1, 2], [3, 4]]).normalized()) raises(ValueError, lambda: Matrix([1, 2]).inv(method='not a method')) raises(NonSquareMatrixError, lambda: Matrix([1, 2]).inverse_GE()) raises(ValueError, lambda: Matrix([[1, 2], [1, 2]]).inverse_GE()) raises(NonSquareMatrixError, lambda: Matrix([1, 2]).inverse_ADJ()) raises(ValueError, lambda: Matrix([[1, 2], [1, 2]]).inverse_ADJ()) raises(NonSquareMatrixError, lambda: Matrix([1, 2]).inverse_LU()) raises(NonSquareMatrixError, lambda: Matrix([1, 2]).is_nilpotent()) raises(NonSquareMatrixError, lambda: Matrix([1, 2]).det()) raises(ValueError, lambda: Matrix([[1, 2], [3, 4]]).det(method='Not a real method')) raises(ValueError, lambda: Matrix([[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12], [13, 14, 15, 16]]).det(iszerofunc="Not function")) raises(ValueError, lambda: Matrix([[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12], [13, 14, 15, 16]]).det(iszerofunc=False)) raises(ValueError, lambda: hessian(Matrix([[1, 2], [3, 4]]), Matrix([[1, 2], [2, 1]]))) raises(ValueError, lambda: hessian(Matrix([[1, 2], [3, 4]]), [])) raises(ValueError, lambda: hessian(Symbol('x')**2, 'a')) raises(IndexError, lambda: eye(3)[5, 2]) raises(IndexError, lambda: eye(3)[2, 5]) M = Matrix(((1, 2, 3, 4), (5, 6, 7, 8), (9, 10, 11, 12), (13, 14, 15, 16))) raises(ValueError, lambda: M.det('method=LU_decomposition()')) V = Matrix([[10, 10, 10]]) M = Matrix([[1, 2, 3], [2, 3, 4], [3, 4, 5]]) raises(ValueError, lambda: M.row_insert(4.7, V)) M = Matrix([[1, 2, 3], [2, 3, 4], [3, 4, 5]]) raises(ValueError, lambda: M.col_insert(-4.2, V)) def test_len(): assert len(Matrix()) == 0 assert len(Matrix([[1, 2]])) == len(Matrix([[1], [2]])) == 2 assert len(Matrix(0, 2, lambda i, j: 0)) == \ len(Matrix(2, 0, lambda i, j: 0)) == 0 assert len(Matrix([[0, 1, 2], [3, 4, 5]])) == 6 assert Matrix([1]) == Matrix([[1]]) assert not Matrix() assert Matrix() == Matrix([]) def test_integrate(): A = Matrix(((1, 4, x), (y, 2, 4), (10, 5, x**2))) assert A.integrate(x) == \ Matrix(((x, 4*x, x**2/2), (x*y, 2*x, 4*x), (10*x, 5*x, x**3/3))) assert A.integrate(y) == \ Matrix(((y, 4*y, x*y), (y**2/2, 2*y, 4*y), (10*y, 5*y, y*x**2))) def test_limit(): A = Matrix(((1, 4, sin(x)/x), (y, 2, 4), (10, 5, x**2 + 1))) assert A.limit(x, 0) == Matrix(((1, 4, 1), (y, 2, 4), (10, 5, 1))) def test_diff(): A = MutableDenseMatrix(((1, 4, x), (y, 2, 4), (10, 5, x**2 + 1))) assert isinstance(A.diff(x), type(A)) assert A.diff(x) == MutableDenseMatrix(((0, 0, 1), (0, 0, 0), (0, 0, 2*x))) assert A.diff(y) == MutableDenseMatrix(((0, 0, 0), (1, 0, 0), (0, 0, 0))) assert diff(A, x) == MutableDenseMatrix(((0, 0, 1), (0, 0, 0), (0, 0, 2*x))) assert diff(A, y) == MutableDenseMatrix(((0, 0, 0), (1, 0, 0), (0, 0, 0))) A_imm = A.as_immutable() assert isinstance(A_imm.diff(x), type(A_imm)) assert A_imm.diff(x) == ImmutableDenseMatrix(((0, 0, 1), (0, 0, 0), (0, 0, 2*x))) assert A_imm.diff(y) == ImmutableDenseMatrix(((0, 0, 0), (1, 0, 0), (0, 0, 0))) assert diff(A_imm, x) == ImmutableDenseMatrix(((0, 0, 1), (0, 0, 0), (0, 0, 2*x))) assert diff(A_imm, y) == ImmutableDenseMatrix(((0, 0, 0), (1, 0, 0), (0, 0, 0))) def test_diff_by_matrix(): # Derive matrix by matrix: A = MutableDenseMatrix([[x, y], [z, t]]) assert A.diff(A) == Array([[[[1, 0], [0, 0]], [[0, 1], [0, 0]]], [[[0, 0], [1, 0]], [[0, 0], [0, 1]]]]) assert diff(A, A) == Array([[[[1, 0], [0, 0]], [[0, 1], [0, 0]]], [[[0, 0], [1, 0]], [[0, 0], [0, 1]]]]) A_imm = A.as_immutable() assert A_imm.diff(A_imm) == Array([[[[1, 0], [0, 0]], [[0, 1], [0, 0]]], [[[0, 0], [1, 0]], [[0, 0], [0, 1]]]]) assert diff(A_imm, A_imm) == Array([[[[1, 0], [0, 0]], [[0, 1], [0, 0]]], [[[0, 0], [1, 0]], [[0, 0], [0, 1]]]]) # Derive a constant matrix: assert A.diff(a) == MutableDenseMatrix([[0, 0], [0, 0]]) B = ImmutableDenseMatrix([a, b]) assert A.diff(B) == A.zeros(2) # Test diff with tuples: dB = B.diff([[a, b]]) assert dB.shape == (2, 2, 1) assert dB == Array([[[1], [0]], [[0], [1]]]) f = Function("f") fxyz = f(x, y, z) assert fxyz.diff([[x, y, z]]) == Array([fxyz.diff(x), fxyz.diff(y), fxyz.diff(z)]) assert fxyz.diff(([x, y, z], 2)) == Array([ [fxyz.diff(x, 2), fxyz.diff(x, y), fxyz.diff(x, z)], [fxyz.diff(x, y), fxyz.diff(y, 2), fxyz.diff(y, z)], [fxyz.diff(x, z), fxyz.diff(z, y), fxyz.diff(z, 2)], ]) expr = sin(x)*exp(y) assert expr.diff([[x, y]]) == Array([cos(x)*exp(y), sin(x)*exp(y)]) assert expr.diff(y, ((x, y),)) == Array([cos(x)*exp(y), sin(x)*exp(y)]) assert expr.diff(x, ((x, y),)) == Array([-sin(x)*exp(y), cos(x)*exp(y)]) assert expr.diff(((y, x),), [[x, y]]) == Array([[cos(x)*exp(y), -sin(x)*exp(y)], [sin(x)*exp(y), cos(x)*exp(y)]]) # Test different notations: fxyz.diff(x).diff(y).diff(x) == fxyz.diff(((x, y, z),), 3)[0, 1, 0] fxyz.diff(z).diff(y).diff(x) == fxyz.diff(((x, y, z),), 3)[2, 1, 0] fxyz.diff([[x, y, z]], ((z, y, x),)) == Array([[fxyz.diff(i).diff(j) for i in (x, y, z)] for j in (z, y, x)]) # Test scalar derived by matrix remains matrix: res = x.diff(Matrix([[x, y]])) assert isinstance(res, ImmutableDenseMatrix) assert res == Matrix([[1, 0]]) res = (x**3).diff(Matrix([[x, y]])) assert isinstance(res, ImmutableDenseMatrix) assert res == Matrix([[3*x**2, 0]]) def test_getattr(): A = Matrix(((1, 4, x), (y, 2, 4), (10, 5, x**2 + 1))) raises(AttributeError, lambda: A.nonexistantattribute) assert getattr(A, 'diff')(x) == Matrix(((0, 0, 1), (0, 0, 0), (0, 0, 2*x))) def test_hessenberg(): A = Matrix([[3, 4, 1], [2, 4, 5], [0, 1, 2]]) assert A.is_upper_hessenberg A = A.T assert A.is_lower_hessenberg A[0, -1] = 1 assert A.is_lower_hessenberg is False A = Matrix([[3, 4, 1], [2, 4, 5], [3, 1, 2]]) assert not A.is_upper_hessenberg A = zeros(5, 2) assert A.is_upper_hessenberg def test_cholesky(): raises(NonSquareMatrixError, lambda: Matrix((1, 2)).cholesky()) raises(ValueError, lambda: Matrix(((1, 2), (3, 4))).cholesky()) raises(ValueError, lambda: Matrix(((5 + I, 0), (0, 1))).cholesky()) raises(ValueError, lambda: Matrix(((1, 5), (5, 1))).cholesky()) raises(ValueError, lambda: Matrix(((1, 2), (3, 4))).cholesky(hermitian=False)) assert Matrix(((5 + I, 0), (0, 1))).cholesky(hermitian=False) == Matrix([ [sqrt(5 + I), 0], [0, 1]]) A = Matrix(((1, 5), (5, 1))) L = A.cholesky(hermitian=False) assert L == Matrix([[1, 0], [5, 2*sqrt(6)*I]]) assert L*L.T == A A = Matrix(((25, 15, -5), (15, 18, 0), (-5, 0, 11))) L = A.cholesky() assert L * L.T == A assert L.is_lower assert L == Matrix([[5, 0, 0], [3, 3, 0], [-1, 1, 3]]) A = Matrix(((4, -2*I, 2 + 2*I), (2*I, 2, -1 + I), (2 - 2*I, -1 - I, 11))) assert A.cholesky() == Matrix(((2, 0, 0), (I, 1, 0), (1 - I, 0, 3))) def test_LDLdecomposition(): raises(NonSquareMatrixError, lambda: Matrix((1, 2)).LDLdecomposition()) raises(ValueError, lambda: Matrix(((1, 2), (3, 4))).LDLdecomposition()) raises(ValueError, lambda: Matrix(((5 + I, 0), (0, 1))).LDLdecomposition()) raises(ValueError, lambda: Matrix(((1, 5), (5, 1))).LDLdecomposition()) raises(ValueError, lambda: Matrix(((1, 2), (3, 4))).LDLdecomposition(hermitian=False)) A = Matrix(((1, 5), (5, 1))) L, D = A.LDLdecomposition(hermitian=False) assert L * D * L.T == A A = Matrix(((25, 15, -5), (15, 18, 0), (-5, 0, 11))) L, D = A.LDLdecomposition() assert L * D * L.T == A assert L.is_lower assert L == Matrix([[1, 0, 0], [ S(3)/5, 1, 0], [S(-1)/5, S(1)/3, 1]]) assert D.is_diagonal() assert D == Matrix([[25, 0, 0], [0, 9, 0], [0, 0, 9]]) A = Matrix(((4, -2*I, 2 + 2*I), (2*I, 2, -1 + I), (2 - 2*I, -1 - I, 11))) L, D = A.LDLdecomposition() assert expand_mul(L * D * L.H) == A assert L == Matrix(((1, 0, 0), (I/2, 1, 0), (S(1)/2 - I/2, 0, 1))) assert D == Matrix(((4, 0, 0), (0, 1, 0), (0, 0, 9))) def test_cholesky_solve(): A = Matrix([[2, 3, 5], [3, 6, 2], [8, 3, 6]]) x = Matrix(3, 1, [3, 7, 5]) b = A*x soln = A.cholesky_solve(b) assert soln == x A = Matrix([[0, -1, 2], [5, 10, 7], [8, 3, 4]]) x = Matrix(3, 1, [-1, 2, 5]) b = A*x soln = A.cholesky_solve(b) assert soln == x A = Matrix(((1, 5), (5, 1))) x = Matrix((4, -3)) b = A*x soln = A.cholesky_solve(b) assert soln == x A = Matrix(((9, 3*I), (-3*I, 5))) x = Matrix((-2, 1)) b = A*x soln = A.cholesky_solve(b) assert expand_mul(soln) == x A = Matrix(((9*I, 3), (-3 + I, 5))) x = Matrix((2 + 3*I, -1)) b = A*x soln = A.cholesky_solve(b) assert expand_mul(soln) == x a00, a01, a11, b0, b1 = symbols('a00, a01, a11, b0, b1') A = Matrix(((a00, a01), (a01, a11))) b = Matrix((b0, b1)) x = A.cholesky_solve(b) assert simplify(A*x) == b def test_LDLsolve(): A = Matrix([[2, 3, 5], [3, 6, 2], [8, 3, 6]]) x = Matrix(3, 1, [3, 7, 5]) b = A*x soln = A.LDLsolve(b) assert soln == x A = Matrix([[0, -1, 2], [5, 10, 7], [8, 3, 4]]) x = Matrix(3, 1, [-1, 2, 5]) b = A*x soln = A.LDLsolve(b) assert soln == x A = Matrix(((9, 3*I), (-3*I, 5))) x = Matrix((-2, 1)) b = A*x soln = A.LDLsolve(b) assert expand_mul(soln) == x A = Matrix(((9*I, 3), (-3 + I, 5))) x = Matrix((2 + 3*I, -1)) b = A*x soln = A.cholesky_solve(b) assert expand_mul(soln) == x def test_lower_triangular_solve(): raises(NonSquareMatrixError, lambda: Matrix([1, 0]).lower_triangular_solve(Matrix([0, 1]))) raises(ShapeError, lambda: Matrix([[1, 0], [0, 1]]).lower_triangular_solve(Matrix([1]))) raises(ValueError, lambda: Matrix([[2, 1], [1, 2]]).lower_triangular_solve( Matrix([[1, 0], [0, 1]]))) A = Matrix([[1, 0], [0, 1]]) B = Matrix([[x, y], [y, x]]) C = Matrix([[4, 8], [2, 9]]) assert A.lower_triangular_solve(B) == B assert A.lower_triangular_solve(C) == C def test_upper_triangular_solve(): raises(NonSquareMatrixError, lambda: Matrix([1, 0]).upper_triangular_solve(Matrix([0, 1]))) raises(TypeError, lambda: Matrix([[1, 0], [0, 1]]).upper_triangular_solve(Matrix([1]))) raises(TypeError, lambda: Matrix([[2, 1], [1, 2]]).upper_triangular_solve( Matrix([[1, 0], [0, 1]]))) A = Matrix([[1, 0], [0, 1]]) B = Matrix([[x, y], [y, x]]) C = Matrix([[2, 4], [3, 8]]) assert A.upper_triangular_solve(B) == B assert A.upper_triangular_solve(C) == C def test_diagonal_solve(): raises(TypeError, lambda: Matrix([1, 1]).diagonal_solve(Matrix([1]))) A = Matrix([[1, 0], [0, 1]])*2 B = Matrix([[x, y], [y, x]]) assert A.diagonal_solve(B) == B/2 def test_matrix_norm(): # Vector Tests # Test columns and symbols x = Symbol('x', real=True) v = Matrix([cos(x), sin(x)]) assert trigsimp(v.norm(2)) == 1 assert v.norm(10) == Pow(cos(x)**10 + sin(x)**10, S(1)/10) # Test Rows A = Matrix([[5, Rational(3, 2)]]) assert A.norm() == Pow(25 + Rational(9, 4), S(1)/2) assert A.norm(oo) == max(A._mat) assert A.norm(-oo) == min(A._mat) # Matrix Tests # Intuitive test A = Matrix([[1, 1], [1, 1]]) assert A.norm(2) == 2 assert A.norm(-2) == 0 assert A.norm('frobenius') == 2 assert eye(10).norm(2) == eye(10).norm(-2) == 1 assert A.norm(oo) == 2 # Test with Symbols and more complex entries A = Matrix([[3, y, y], [x, S(1)/2, -pi]]) assert (A.norm('fro') == sqrt(S(37)/4 + 2*abs(y)**2 + pi**2 + x**2)) # Check non-square A = Matrix([[1, 2, -3], [4, 5, Rational(13, 2)]]) assert A.norm(2) == sqrt(S(389)/8 + sqrt(78665)/8) assert A.norm(-2) == S(0) assert A.norm('frobenius') == sqrt(389)/2 # Test properties of matrix norms # https://en.wikipedia.org/wiki/Matrix_norm#Definition # Two matrices A = Matrix([[1, 2], [3, 4]]) B = Matrix([[5, 5], [-2, 2]]) C = Matrix([[0, -I], [I, 0]]) D = Matrix([[1, 0], [0, -1]]) L = [A, B, C, D] alpha = Symbol('alpha', real=True) for order in ['fro', 2, -2]: # Zero Check assert zeros(3).norm(order) == S(0) # Check Triangle Inequality for all Pairs of Matrices for X in L: for Y in L: dif = (X.norm(order) + Y.norm(order) - (X + Y).norm(order)) assert (dif >= 0) # Scalar multiplication linearity for M in [A, B, C, D]: dif = simplify((alpha*M).norm(order) - abs(alpha) * M.norm(order)) assert dif == 0 # Test Properties of Vector Norms # https://en.wikipedia.org/wiki/Vector_norm # Two column vectors a = Matrix([1, 1 - 1*I, -3]) b = Matrix([S(1)/2, 1*I, 1]) c = Matrix([-1, -1, -1]) d = Matrix([3, 2, I]) e = Matrix([Integer(1e2), Rational(1, 1e2), 1]) L = [a, b, c, d, e] alpha = Symbol('alpha', real=True) for order in [1, 2, -1, -2, S.Infinity, S.NegativeInfinity, pi]: # Zero Check if order > 0: assert Matrix([0, 0, 0]).norm(order) == S(0) # Triangle inequality on all pairs if order >= 1: # Triangle InEq holds only for these norms for X in L: for Y in L: dif = (X.norm(order) + Y.norm(order) - (X + Y).norm(order)) assert simplify(dif >= 0) is S.true # Linear to scalar multiplication if order in [1, 2, -1, -2, S.Infinity, S.NegativeInfinity]: for X in L: dif = simplify((alpha*X).norm(order) - (abs(alpha) * X.norm(order))) assert dif == 0 # ord=1 M = Matrix(3, 3, [1, 3, 0, -2, -1, 0, 3, 9, 6]) assert M.norm(1) == 13 def test_condition_number(): x = Symbol('x', real=True) A = eye(3) A[0, 0] = 10 A[2, 2] = S(1)/10 assert A.condition_number() == 100 A[1, 1] = x assert A.condition_number() == Max(10, Abs(x)) / Min(S(1)/10, Abs(x)) M = Matrix([[cos(x), sin(x)], [-sin(x), cos(x)]]) Mc = M.condition_number() assert all(Float(1.).epsilon_eq(Mc.subs(x, val).evalf()) for val in [Rational(1, 5), Rational(1, 2), Rational(1, 10), pi/2, pi, 7*pi/4 ]) #issue 10782 assert Matrix([]).condition_number() == 0 def test_equality(): A = Matrix(((1, 2, 3), (4, 5, 6), (7, 8, 9))) B = Matrix(((9, 8, 7), (6, 5, 4), (3, 2, 1))) assert A == A[:, :] assert not A != A[:, :] assert not A == B assert A != B assert A != 10 assert not A == 10 # A SparseMatrix can be equal to a Matrix C = SparseMatrix(((1, 0, 0), (0, 1, 0), (0, 0, 1))) D = Matrix(((1, 0, 0), (0, 1, 0), (0, 0, 1))) assert C == D assert not C != D def test_col_join(): assert eye(3).col_join(Matrix([[7, 7, 7]])) == \ Matrix([[1, 0, 0], [0, 1, 0], [0, 0, 1], [7, 7, 7]]) def test_row_insert(): r4 = Matrix([[4, 4, 4]]) for i in range(-4, 5): l = [1, 0, 0] l.insert(i, 4) assert flatten(eye(3).row_insert(i, r4).col(0).tolist()) == l def test_col_insert(): c4 = Matrix([4, 4, 4]) for i in range(-4, 5): l = [0, 0, 0] l.insert(i, 4) assert flatten(zeros(3).col_insert(i, c4).row(0).tolist()) == l def test_normalized(): assert Matrix([3, 4]).normalized() == \ Matrix([Rational(3, 5), Rational(4, 5)]) # Zero vector trivial cases assert Matrix([0, 0, 0]).normalized() == Matrix([0, 0, 0]) # Machine precision error truncation trivial cases m = Matrix([0,0,1.e-100]) assert m.normalized( iszerofunc=lambda x: x.evalf(n=10, chop=True).is_zero ) == Matrix([0, 0, 0]) def test_print_nonzero(): assert capture(lambda: eye(3).print_nonzero()) == \ '[X ]\n[ X ]\n[ X]\n' assert capture(lambda: eye(3).print_nonzero('.')) == \ '[. ]\n[ . ]\n[ .]\n' def test_zeros_eye(): assert Matrix.eye(3) == eye(3) assert Matrix.zeros(3) == zeros(3) assert ones(3, 4) == Matrix(3, 4, [1]*12) i = Matrix([[1, 0], [0, 1]]) z = Matrix([[0, 0], [0, 0]]) for cls in classes: m = cls.eye(2) assert i == m # but m == i will fail if m is immutable assert i == eye(2, cls=cls) assert type(m) == cls m = cls.zeros(2) assert z == m assert z == zeros(2, cls=cls) assert type(m) == cls def test_is_zero(): assert Matrix().is_zero assert Matrix([[0, 0], [0, 0]]).is_zero assert zeros(3, 4).is_zero assert not eye(3).is_zero assert Matrix([[x, 0], [0, 0]]).is_zero == None assert SparseMatrix([[x, 0], [0, 0]]).is_zero == None assert ImmutableMatrix([[x, 0], [0, 0]]).is_zero == None assert ImmutableSparseMatrix([[x, 0], [0, 0]]).is_zero == None assert Matrix([[x, 1], [0, 0]]).is_zero == False a = Symbol('a', nonzero=True) assert Matrix([[a, 0], [0, 0]]).is_zero == False def test_rotation_matrices(): # This tests the rotation matrices by rotating about an axis and back. theta = pi/3 r3_plus = rot_axis3(theta) r3_minus = rot_axis3(-theta) r2_plus = rot_axis2(theta) r2_minus = rot_axis2(-theta) r1_plus = rot_axis1(theta) r1_minus = rot_axis1(-theta) assert r3_minus*r3_plus*eye(3) == eye(3) assert r2_minus*r2_plus*eye(3) == eye(3) assert r1_minus*r1_plus*eye(3) == eye(3) # Check the correctness of the trace of the rotation matrix assert r1_plus.trace() == 1 + 2*cos(theta) assert r2_plus.trace() == 1 + 2*cos(theta) assert r3_plus.trace() == 1 + 2*cos(theta) # Check that a rotation with zero angle doesn't change anything. assert rot_axis1(0) == eye(3) assert rot_axis2(0) == eye(3) assert rot_axis3(0) == eye(3) def test_DeferredVector(): assert str(DeferredVector("vector")[4]) == "vector[4]" assert sympify(DeferredVector("d")) == DeferredVector("d") def test_DeferredVector_not_iterable(): assert not iterable(DeferredVector('X')) def test_DeferredVector_Matrix(): raises(TypeError, lambda: Matrix(DeferredVector("V"))) def test_GramSchmidt(): R = Rational m1 = Matrix(1, 2, [1, 2]) m2 = Matrix(1, 2, [2, 3]) assert GramSchmidt([m1, m2]) == \ [Matrix(1, 2, [1, 2]), Matrix(1, 2, [R(2)/5, R(-1)/5])] assert GramSchmidt([m1.T, m2.T]) == \ [Matrix(2, 1, [1, 2]), Matrix(2, 1, [R(2)/5, R(-1)/5])] # from wikipedia assert GramSchmidt([Matrix([3, 1]), Matrix([2, 2])], True) == [ Matrix([3*sqrt(10)/10, sqrt(10)/10]), Matrix([-sqrt(10)/10, 3*sqrt(10)/10])] def test_casoratian(): assert casoratian([1, 2, 3, 4], 1) == 0 assert casoratian([1, 2, 3, 4], 1, zero=False) == 0 def test_zero_dimension_multiply(): assert (Matrix()*zeros(0, 3)).shape == (0, 3) assert zeros(3, 0)*zeros(0, 3) == zeros(3, 3) assert zeros(0, 3)*zeros(3, 0) == Matrix() def test_slice_issue_2884(): m = Matrix(2, 2, range(4)) assert m[1, :] == Matrix([[2, 3]]) assert m[-1, :] == Matrix([[2, 3]]) assert m[:, 1] == Matrix([[1, 3]]).T assert m[:, -1] == Matrix([[1, 3]]).T raises(IndexError, lambda: m[2, :]) raises(IndexError, lambda: m[2, 2]) def test_slice_issue_3401(): assert zeros(0, 3)[:, -1].shape == (0, 1) assert zeros(3, 0)[0, :] == Matrix(1, 0, []) def test_copyin(): s = zeros(3, 3) s[3] = 1 assert s[:, 0] == Matrix([0, 1, 0]) assert s[3] == 1 assert s[3: 4] == [1] s[1, 1] = 42 assert s[1, 1] == 42 assert s[1, 1:] == Matrix([[42, 0]]) s[1, 1:] = Matrix([[5, 6]]) assert s[1, :] == Matrix([[1, 5, 6]]) s[1, 1:] = [[42, 43]] assert s[1, :] == Matrix([[1, 42, 43]]) s[0, 0] = 17 assert s[:, :1] == Matrix([17, 1, 0]) s[0, 0] = [1, 1, 1] assert s[:, 0] == Matrix([1, 1, 1]) s[0, 0] = Matrix([1, 1, 1]) assert s[:, 0] == Matrix([1, 1, 1]) s[0, 0] = SparseMatrix([1, 1, 1]) assert s[:, 0] == Matrix([1, 1, 1]) def test_invertible_check(): # sometimes a singular matrix will have a pivot vector shorter than # the number of rows in a matrix... assert Matrix([[1, 2], [1, 2]]).rref() == (Matrix([[1, 2], [0, 0]]), (0,)) raises(ValueError, lambda: Matrix([[1, 2], [1, 2]]).inv()) m = Matrix([ [-1, -1, 0], [ x, 1, 1], [ 1, x, -1], ]) assert len(m.rref()[1]) != m.rows # in addition, unless simplify=True in the call to rref, the identity # matrix will be returned even though m is not invertible assert m.rref()[0] != eye(3) assert m.rref(simplify=signsimp)[0] != eye(3) raises(ValueError, lambda: m.inv(method="ADJ")) raises(ValueError, lambda: m.inv(method="GE")) raises(ValueError, lambda: m.inv(method="LU")) @XFAIL def test_issue_3959(): x, y = symbols('x, y') e = x*y assert e.subs(x, Matrix([3, 5, 3])) == Matrix([3, 5, 3])*y def test_issue_5964(): assert str(Matrix([[1, 2], [3, 4]])) == 'Matrix([[1, 2], [3, 4]])' def test_issue_7604(): x, y = symbols(u"x y") assert sstr(Matrix([[x, 2*y], [y**2, x + 3]])) == \ 'Matrix([\n[ x, 2*y],\n[y**2, x + 3]])' def test_is_Identity(): assert eye(3).is_Identity assert eye(3).as_immutable().is_Identity assert not zeros(3).is_Identity assert not ones(3).is_Identity # issue 6242 assert not Matrix([[1, 0, 0]]).is_Identity # issue 8854 assert SparseMatrix(3,3, {(0,0):1, (1,1):1, (2,2):1}).is_Identity assert not SparseMatrix(2,3, range(6)).is_Identity assert not SparseMatrix(3,3, {(0,0):1, (1,1):1}).is_Identity assert not SparseMatrix(3,3, {(0,0):1, (1,1):1, (2,2):1, (0,1):2, (0,2):3}).is_Identity def test_dot(): assert ones(1, 3).dot(ones(3, 1)) == 3 assert ones(1, 3).dot([1, 1, 1]) == 3 assert Matrix([1, 2, 3]).dot(Matrix([1, 2, 3])) == 14 assert Matrix([1, 2, 3*I]).dot(Matrix([I, 2, 3*I])) == -5 + I assert Matrix([1, 2, 3*I]).dot(Matrix([I, 2, 3*I]), hermitian=False) == -5 + I assert Matrix([1, 2, 3*I]).dot(Matrix([I, 2, 3*I]), hermitian=True) == 13 + I assert Matrix([1, 2, 3*I]).dot(Matrix([I, 2, 3*I]), hermitian=True, conjugate_convention="physics") == 13 - I assert Matrix([1, 2, 3*I]).dot(Matrix([4, 5*I, 6]), hermitian=True, conjugate_convention="right") == 4 + 8*I assert Matrix([1, 2, 3*I]).dot(Matrix([4, 5*I, 6]), hermitian=True, conjugate_convention="left") == 4 - 8*I assert Matrix([I, 2*I]).dot(Matrix([I, 2*I]), hermitian=False, conjugate_convention="left") == -5 assert Matrix([I, 2*I]).dot(Matrix([I, 2*I]), conjugate_convention="left") == 5 def test_dual(): B_x, B_y, B_z, E_x, E_y, E_z = symbols( 'B_x B_y B_z E_x E_y E_z', real=True) F = Matrix(( ( 0, E_x, E_y, E_z), (-E_x, 0, B_z, -B_y), (-E_y, -B_z, 0, B_x), (-E_z, B_y, -B_x, 0) )) Fd = Matrix(( ( 0, -B_x, -B_y, -B_z), (B_x, 0, E_z, -E_y), (B_y, -E_z, 0, E_x), (B_z, E_y, -E_x, 0) )) assert F.dual().equals(Fd) assert eye(3).dual().equals(zeros(3)) assert F.dual().dual().equals(-F) def test_anti_symmetric(): assert Matrix([1, 2]).is_anti_symmetric() is False m = Matrix(3, 3, [0, x**2 + 2*x + 1, y, -(x + 1)**2, 0, x*y, -y, -x*y, 0]) assert m.is_anti_symmetric() is True assert m.is_anti_symmetric(simplify=False) is False assert m.is_anti_symmetric(simplify=lambda x: x) is False # tweak to fail m[2, 1] = -m[2, 1] assert m.is_anti_symmetric() is False # untweak m[2, 1] = -m[2, 1] m = m.expand() assert m.is_anti_symmetric(simplify=False) is True m[0, 0] = 1 assert m.is_anti_symmetric() is False def test_normalize_sort_diogonalization(): A = Matrix(((1, 2), (2, 1))) P, Q = A.diagonalize(normalize=True) assert P*P.T == P.T*P == eye(P.cols) P, Q = A.diagonalize(normalize=True, sort=True) assert P*P.T == P.T*P == eye(P.cols) assert P*Q*P.inv() == A def test_issue_5321(): raises(ValueError, lambda: Matrix([[1, 2, 3], Matrix(0, 1, [])])) def test_issue_5320(): assert Matrix.hstack(eye(2), 2*eye(2)) == Matrix([ [1, 0, 2, 0], [0, 1, 0, 2] ]) assert Matrix.vstack(eye(2), 2*eye(2)) == Matrix([ [1, 0], [0, 1], [2, 0], [0, 2] ]) cls = SparseMatrix assert cls.hstack(cls(eye(2)), cls(2*eye(2))) == Matrix([ [1, 0, 2, 0], [0, 1, 0, 2] ]) def test_issue_11944(): A = Matrix([[1]]) AIm = sympify(A) assert Matrix.hstack(AIm, A) == Matrix([[1, 1]]) assert Matrix.vstack(AIm, A) == Matrix([[1], [1]]) def test_cross(): a = [1, 2, 3] b = [3, 4, 5] col = Matrix([-2, 4, -2]) row = col.T def test(M, ans): assert ans == M assert type(M) == cls for cls in classes: A = cls(a) B = cls(b) test(A.cross(B), col) test(A.cross(B.T), col) test(A.T.cross(B.T), row) test(A.T.cross(B), row) raises(ShapeError, lambda: Matrix(1, 2, [1, 1]).cross(Matrix(1, 2, [1, 1]))) def test_hash(): for cls in classes[-2:]: s = {cls.eye(1), cls.eye(1)} assert len(s) == 1 and s.pop() == cls.eye(1) # issue 3979 for cls in classes[:2]: assert not isinstance(cls.eye(1), Hashable) @XFAIL def test_issue_3979(): # when this passes, delete this and change the [1:2] # to [:2] in the test_hash above for issue 3979 cls = classes[0] raises(AttributeError, lambda: hash(cls.eye(1))) def test_adjoint(): dat = [[0, I], [1, 0]] ans = Matrix([[0, 1], [-I, 0]]) for cls in classes: assert ans == cls(dat).adjoint() def test_simplify_immutable(): from sympy import simplify, sin, cos assert simplify(ImmutableMatrix([[sin(x)**2 + cos(x)**2]])) == \ ImmutableMatrix([[1]]) def test_rank(): from sympy.abc import x m = Matrix([[1, 2], [x, 1 - 1/x]]) assert m.rank() == 2 n = Matrix(3, 3, range(1, 10)) assert n.rank() == 2 p = zeros(3) assert p.rank() == 0 def test_issue_11434(): ax, ay, bx, by, cx, cy, dx, dy, ex, ey, t0, t1 = \ symbols('a_x a_y b_x b_y c_x c_y d_x d_y e_x e_y t_0 t_1') M = Matrix([[ax, ay, ax*t0, ay*t0, 0], [bx, by, bx*t0, by*t0, 0], [cx, cy, cx*t0, cy*t0, 1], [dx, dy, dx*t0, dy*t0, 1], [ex, ey, 2*ex*t1 - ex*t0, 2*ey*t1 - ey*t0, 0]]) assert M.rank() == 4 def test_rank_regression_from_so(): # see: # https://stackoverflow.com/questions/19072700/why-does-sympy-give-me-the-wrong-answer-when-i-row-reduce-a-symbolic-matrix nu, lamb = symbols('nu, lambda') A = Matrix([[-3*nu, 1, 0, 0], [ 3*nu, -2*nu - 1, 2, 0], [ 0, 2*nu, (-1*nu) - lamb - 2, 3], [ 0, 0, nu + lamb, -3]]) expected_reduced = Matrix([[1, 0, 0, 1/(nu**2*(-lamb - nu))], [0, 1, 0, 3/(nu*(-lamb - nu))], [0, 0, 1, 3/(-lamb - nu)], [0, 0, 0, 0]]) expected_pivots = (0, 1, 2) reduced, pivots = A.rref() assert simplify(expected_reduced - reduced) == zeros(*A.shape) assert pivots == expected_pivots def test_replace(): from sympy import symbols, Function, Matrix F, G = symbols('F, G', cls=Function) K = Matrix(2, 2, lambda i, j: G(i+j)) M = Matrix(2, 2, lambda i, j: F(i+j)) N = M.replace(F, G) assert N == K def test_replace_map(): from sympy import symbols, Function, Matrix F, G = symbols('F, G', cls=Function) K = Matrix(2, 2, [(G(0), {F(0): G(0)}), (G(1), {F(1): G(1)}), (G(1), {F(1)\ : G(1)}), (G(2), {F(2): G(2)})]) M = Matrix(2, 2, lambda i, j: F(i+j)) N = M.replace(F, G, True) assert N == K def test_atoms(): m = Matrix([[1, 2], [x, 1 - 1/x]]) assert m.atoms() == {S(1),S(2),S(-1), x} assert m.atoms(Symbol) == {x} @slow def test_pinv(): # Pseudoinverse of an invertible matrix is the inverse. A1 = Matrix([[a, b], [c, d]]) assert simplify(A1.pinv()) == simplify(A1.inv()) # Test the four properties of the pseudoinverse for various matrices. As = [Matrix([[13, 104], [2212, 3], [-3, 5]]), Matrix([[1, 7, 9], [11, 17, 19]]), Matrix([a, b])] for A in As: A_pinv = A.pinv() AAp = A * A_pinv ApA = A_pinv * A assert simplify(AAp * A) == A assert simplify(ApA * A_pinv) == A_pinv assert AAp.H == AAp assert ApA.H == ApA def test_pinv_solve(): # Fully determined system (unique result, identical to other solvers). A = Matrix([[1, 5], [7, 9]]) B = Matrix([12, 13]) assert A.pinv_solve(B) == A.cholesky_solve(B) assert A.pinv_solve(B) == A.LDLsolve(B) assert A.pinv_solve(B) == Matrix([sympify('-43/26'), sympify('71/26')]) assert A * A.pinv() * B == B # Fully determined, with two-dimensional B matrix. B = Matrix([[12, 13, 14], [15, 16, 17]]) assert A.pinv_solve(B) == A.cholesky_solve(B) assert A.pinv_solve(B) == A.LDLsolve(B) assert A.pinv_solve(B) == Matrix([[-33, -37, -41], [69, 75, 81]]) / 26 assert A * A.pinv() * B == B # Underdetermined system (infinite results). A = Matrix([[1, 0, 1], [0, 1, 1]]) B = Matrix([5, 7]) solution = A.pinv_solve(B) w = {} for s in solution.atoms(Symbol): # Extract dummy symbols used in the solution. w[s.name] = s assert solution == Matrix([[w['w0_0']/3 + w['w1_0']/3 - w['w2_0']/3 + 1], [w['w0_0']/3 + w['w1_0']/3 - w['w2_0']/3 + 3], [-w['w0_0']/3 - w['w1_0']/3 + w['w2_0']/3 + 4]]) assert A * A.pinv() * B == B # Overdetermined system (least squares results). A = Matrix([[1, 0], [0, 0], [0, 1]]) B = Matrix([3, 2, 1]) assert A.pinv_solve(B) == Matrix([3, 1]) # Proof the solution is not exact. assert A * A.pinv() * B != B def test_pinv_rank_deficient(): # Test the four properties of the pseudoinverse for various matrices. As = [Matrix([[1, 1, 1], [2, 2, 2]]), Matrix([[1, 0], [0, 0]]), Matrix([[1, 2], [2, 4], [3, 6]])] for A in As: A_pinv = A.pinv() AAp = A * A_pinv ApA = A_pinv * A assert simplify(AAp * A) == A assert simplify(ApA * A_pinv) == A_pinv assert AAp.H == AAp assert ApA.H == ApA # Test solving with rank-deficient matrices. A = Matrix([[1, 0], [0, 0]]) # Exact, non-unique solution. B = Matrix([3, 0]) solution = A.pinv_solve(B) w1 = solution.atoms(Symbol).pop() assert w1.name == 'w1_0' assert solution == Matrix([3, w1]) assert A * A.pinv() * B == B # Least squares, non-unique solution. B = Matrix([3, 1]) solution = A.pinv_solve(B) w1 = solution.atoms(Symbol).pop() assert w1.name == 'w1_0' assert solution == Matrix([3, w1]) assert A * A.pinv() * B != B @XFAIL def test_pinv_rank_deficient_when_diagonalization_fails(): # Test the four properties of the pseudoinverse for matrices when # diagonalization of A.H*A fails.' As = [Matrix([ [61, 89, 55, 20, 71, 0], [62, 96, 85, 85, 16, 0], [69, 56, 17, 4, 54, 0], [10, 54, 91, 41, 71, 0], [ 7, 30, 10, 48, 90, 0], [0,0,0,0,0,0]])] for A in As: A_pinv = A.pinv() AAp = A * A_pinv ApA = A_pinv * A assert simplify(AAp * A) == A assert simplify(ApA * A_pinv) == A_pinv assert AAp.H == AAp assert ApA.H == ApA def test_gauss_jordan_solve(): # Square, full rank, unique solution A = Matrix([[1, 2, 3], [4, 5, 6], [7, 8, 10]]) b = Matrix([3, 6, 9]) sol, params = A.gauss_jordan_solve(b) assert sol == Matrix([[-1], [2], [0]]) assert params == Matrix(0, 1, []) # Square, reduced rank, parametrized solution A = Matrix([[1, 2, 3], [4, 5, 6], [7, 8, 9]]) b = Matrix([3, 6, 9]) sol, params, freevar = A.gauss_jordan_solve(b, freevar=True) w = {} for s in sol.atoms(Symbol): # Extract dummy symbols used in the solution. w[s.name] = s assert sol == Matrix([[w['tau0'] - 1], [-2*w['tau0'] + 2], [w['tau0']]]) assert params == Matrix([[w['tau0']]]) assert freevar == [2] # Square, reduced rank, parametrized solution A = Matrix([[1, 2, 3], [2, 4, 6], [3, 6, 9]]) b = Matrix([0, 0, 0]) sol, params = A.gauss_jordan_solve(b) w = {} for s in sol.atoms(Symbol): w[s.name] = s assert sol == Matrix([[-2*w['tau0'] - 3*w['tau1']], [w['tau0']], [w['tau1']]]) assert params == Matrix([[w['tau0']], [w['tau1']]]) # Square, reduced rank, parametrized solution A = Matrix([[0, 0, 0], [0, 0, 0], [0, 0, 0]]) b = Matrix([0, 0, 0]) sol, params = A.gauss_jordan_solve(b) w = {} for s in sol.atoms(Symbol): w[s.name] = s assert sol == Matrix([[w['tau0']], [w['tau1']], [w['tau2']]]) assert params == Matrix([[w['tau0']], [w['tau1']], [w['tau2']]]) # Square, reduced rank, no solution A = Matrix([[1, 2, 3], [2, 4, 6], [3, 6, 9]]) b = Matrix([0, 0, 1]) raises(ValueError, lambda: A.gauss_jordan_solve(b)) # Rectangular, tall, full rank, unique solution A = Matrix([[1, 5, 3], [2, 1, 6], [1, 7, 9], [1, 4, 3]]) b = Matrix([0, 0, 1, 0]) sol, params = A.gauss_jordan_solve(b) assert sol == Matrix([[-S(1)/2], [0], [S(1)/6]]) assert params == Matrix(0, 1, []) # Rectangular, tall, full rank, no solution A = Matrix([[1, 5, 3], [2, 1, 6], [1, 7, 9], [1, 4, 3]]) b = Matrix([0, 0, 0, 1]) raises(ValueError, lambda: A.gauss_jordan_solve(b)) # Rectangular, tall, reduced rank, parametrized solution A = Matrix([[1, 5, 3], [2, 10, 6], [3, 15, 9], [1, 4, 3]]) b = Matrix([0, 0, 0, 1]) sol, params = A.gauss_jordan_solve(b) w = {} for s in sol.atoms(Symbol): w[s.name] = s assert sol == Matrix([[-3*w['tau0'] + 5], [-1], [w['tau0']]]) assert params == Matrix([[w['tau0']]]) # Rectangular, tall, reduced rank, no solution A = Matrix([[1, 5, 3], [2, 10, 6], [3, 15, 9], [1, 4, 3]]) b = Matrix([0, 0, 1, 1]) raises(ValueError, lambda: A.gauss_jordan_solve(b)) # Rectangular, wide, full rank, parametrized solution A = Matrix([[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 1, 12]]) b = Matrix([1, 1, 1]) sol, params = A.gauss_jordan_solve(b) w = {} for s in sol.atoms(Symbol): w[s.name] = s assert sol == Matrix([[2*w['tau0'] - 1], [-3*w['tau0'] + 1], [0], [w['tau0']]]) assert params == Matrix([[w['tau0']]]) # Rectangular, wide, reduced rank, parametrized solution A = Matrix([[1, 2, 3, 4], [5, 6, 7, 8], [2, 4, 6, 8]]) b = Matrix([0, 1, 0]) sol, params = A.gauss_jordan_solve(b) w = {} for s in sol.atoms(Symbol): w[s.name] = s assert sol == Matrix([[w['tau0'] + 2*w['tau1'] + 1/S(2)], [-2*w['tau0'] - 3*w['tau1'] - 1/S(4)], [w['tau0']], [w['tau1']]]) assert params == Matrix([[w['tau0']], [w['tau1']]]) # watch out for clashing symbols x0, x1, x2, _x0 = symbols('_tau0 _tau1 _tau2 tau1') M = Matrix([[0, 1, 0, 0, 0, 0], [0, 0, 0, 1, 0, _x0]]) A = M[:, :-1] b = M[:, -1:] sol, params = A.gauss_jordan_solve(b) assert params == Matrix(3, 1, [x0, x1, x2]) assert sol == Matrix(5, 1, [x1, 0, x0, _x0, x2]) # Rectangular, wide, reduced rank, no solution A = Matrix([[1, 2, 3, 4], [5, 6, 7, 8], [2, 4, 6, 8]]) b = Matrix([1, 1, 1]) raises(ValueError, lambda: A.gauss_jordan_solve(b)) def test_solve(): A = Matrix([[1,2], [2,4]]) b = Matrix([[3], [4]]) raises(ValueError, lambda: A.solve(b)) #no solution b = Matrix([[ 4], [8]]) raises(ValueError, lambda: A.solve(b)) #infinite solution def test_issue_7201(): assert ones(0, 1) + ones(0, 1) == Matrix(0, 1, []) assert ones(1, 0) + ones(1, 0) == Matrix(1, 0, []) def test_free_symbols(): for M in ImmutableMatrix, ImmutableSparseMatrix, Matrix, SparseMatrix: assert M([[x], [0]]).free_symbols == {x} def test_from_ndarray(): """See issue 7465.""" try: from numpy import array except ImportError: skip('NumPy must be available to test creating matrices from ndarrays') assert Matrix(array([1, 2, 3])) == Matrix([1, 2, 3]) assert Matrix(array([[1, 2, 3]])) == Matrix([[1, 2, 3]]) assert Matrix(array([[1, 2, 3], [4, 5, 6]])) == \ Matrix([[1, 2, 3], [4, 5, 6]]) assert Matrix(array([x, y, z])) == Matrix([x, y, z]) raises(NotImplementedError, lambda: Matrix(array([[ [1, 2], [3, 4]], [[5, 6], [7, 8]]]))) def test_hermitian(): a = Matrix([[1, I], [-I, 1]]) assert a.is_hermitian a[0, 0] = 2*I assert a.is_hermitian is False a[0, 0] = x assert a.is_hermitian is None a[0, 1] = a[1, 0]*I assert a.is_hermitian is False def test_doit(): a = Matrix([[Add(x,x, evaluate=False)]]) assert a[0] != 2*x assert a.doit() == Matrix([[2*x]]) def test_issue_9457_9467_9876(): # for row_del(index) M = Matrix([[1, 2, 3], [2, 3, 4], [3, 4, 5]]) M.row_del(1) assert M == Matrix([[1, 2, 3], [3, 4, 5]]) N = Matrix([[1, 2, 3], [2, 3, 4], [3, 4, 5]]) N.row_del(-2) assert N == Matrix([[1, 2, 3], [3, 4, 5]]) O = Matrix([[1, 2, 3], [5, 6, 7], [9, 10, 11]]) O.row_del(-1) assert O == Matrix([[1, 2, 3], [5, 6, 7]]) P = Matrix([[1, 2, 3], [2, 3, 4], [3, 4, 5]]) raises(IndexError, lambda: P.row_del(10)) Q = Matrix([[1, 2, 3], [2, 3, 4], [3, 4, 5]]) raises(IndexError, lambda: Q.row_del(-10)) # for col_del(index) M = Matrix([[1, 2, 3], [2, 3, 4], [3, 4, 5]]) M.col_del(1) assert M == Matrix([[1, 3], [2, 4], [3, 5]]) N = Matrix([[1, 2, 3], [2, 3, 4], [3, 4, 5]]) N.col_del(-2) assert N == Matrix([[1, 3], [2, 4], [3, 5]]) P = Matrix([[1, 2, 3], [2, 3, 4], [3, 4, 5]]) raises(IndexError, lambda: P.col_del(10)) Q = Matrix([[1, 2, 3], [2, 3, 4], [3, 4, 5]]) raises(IndexError, lambda: Q.col_del(-10)) def test_issue_9422(): x, y = symbols('x y', commutative=False) a, b = symbols('a b') M = eye(2) M1 = Matrix(2, 2, [x, y, y, z]) assert y*x*M != x*y*M assert b*a*M == a*b*M assert x*M1 != M1*x assert a*M1 == M1*a assert y*x*M == Matrix([[y*x, 0], [0, y*x]]) def test_issue_10770(): M = Matrix([]) a = ['col_insert', 'row_join'], Matrix([9, 6, 3]) b = ['row_insert', 'col_join'], a[1].T c = ['row_insert', 'col_insert'], Matrix([[1, 2], [3, 4]]) for ops, m in (a, b, c): for op in ops: f = getattr(M, op) new = f(m) if 'join' in op else f(42, m) assert new == m and id(new) != id(m) def test_issue_10658(): A = Matrix([[1, 2, 3], [4, 5, 6], [7, 8, 9]]) assert A.extract([0, 1, 2], [True, True, False]) == \ Matrix([[1, 2], [4, 5], [7, 8]]) assert A.extract([0, 1, 2], [True, False, False]) == Matrix([[1], [4], [7]]) assert A.extract([True, False, False], [0, 1, 2]) == Matrix([[1, 2, 3]]) assert A.extract([True, False, True], [0, 1, 2]) == \ Matrix([[1, 2, 3], [7, 8, 9]]) assert A.extract([0, 1, 2], [False, False, False]) == Matrix(3, 0, []) assert A.extract([False, False, False], [0, 1, 2]) == Matrix(0, 3, []) assert A.extract([True, False, True], [False, True, False]) == \ Matrix([[2], [8]]) def test_opportunistic_simplification(): # this test relates to issue #10718, #9480, #11434 # issue #9480 m = Matrix([[-5 + 5*sqrt(2), -5], [-5*sqrt(2)/2 + 5, -5*sqrt(2)/2]]) assert m.rank() == 1 # issue #10781 m = Matrix([[3+3*sqrt(3)*I, -9],[4,-3+3*sqrt(3)*I]]) assert simplify(m.rref()[0] - Matrix([[1, -9/(3 + 3*sqrt(3)*I)], [0, 0]])) == zeros(2, 2) # issue #11434 ax,ay,bx,by,cx,cy,dx,dy,ex,ey,t0,t1 = symbols('a_x a_y b_x b_y c_x c_y d_x d_y e_x e_y t_0 t_1') m = Matrix([[ax,ay,ax*t0,ay*t0,0],[bx,by,bx*t0,by*t0,0],[cx,cy,cx*t0,cy*t0,1],[dx,dy,dx*t0,dy*t0,1],[ex,ey,2*ex*t1-ex*t0,2*ey*t1-ey*t0,0]]) assert m.rank() == 4 def test_partial_pivoting(): # example from https://en.wikipedia.org/wiki/Pivot_element # partial pivoting with back subsitution gives a perfect result # naive pivoting give an error ~1e-13, so anything better than # 1e-15 is good mm=Matrix([[0.003 ,59.14, 59.17],[ 5.291, -6.13,46.78]]) assert (mm.rref()[0] - Matrix([[1.0, 0, 10.0], [ 0, 1.0, 1.0]])).norm() < 1e-15 # issue #11549 m_mixed = Matrix([[6e-17, 1.0, 4],[ -1.0, 0, 8],[ 0, 0, 1]]) m_float = Matrix([[6e-17, 1.0, 4.],[ -1.0, 0., 8.],[ 0., 0., 1.]]) m_inv = Matrix([[ 0, -1.0, 8.0],[1.0, 6.0e-17, -4.0],[ 0, 0, 1]]) # this example is numerically unstable and involves a matrix with a norm >= 8, # this comparing the difference of the results with 1e-15 is numerically sound. assert (m_mixed.inv() - m_inv).norm() < 1e-15 assert (m_float.inv() - m_inv).norm() < 1e-15 def test_iszero_substitution(): """ When doing numerical computations, all elements that pass the iszerofunc test should be set to numerically zero if they aren't already. """ # Matrix from issue #9060 m = Matrix([[0.9, -0.1, -0.2, 0],[-0.8, 0.9, -0.4, 0],[-0.1, -0.8, 0.6, 0]]) m_rref = m.rref(iszerofunc=lambda x: abs(x)<6e-15)[0] m_correct = Matrix([[1.0, 0, -0.301369863013699, 0],[ 0, 1.0, -0.712328767123288, 0],[ 0, 0, 0, 0]]) m_diff = m_rref - m_correct assert m_diff.norm() < 1e-15 # if a zero-substitution wasn't made, this entry will be -1.11022302462516e-16 assert m_rref[2,2] == 0 @slow def test_issue_11238(): from sympy import Point xx = 8*tan(13*pi/45)/(tan(13*pi/45) + sqrt(3)) yy = (-8*sqrt(3)*tan(13*pi/45)**2 + 24*tan(13*pi/45))/(-3 + tan(13*pi/45)**2) p1 = Point(0, 0) p2 = Point(1, -sqrt(3)) p0 = Point(xx,yy) m1 = Matrix([p1 - simplify(p0), p2 - simplify(p0)]) m2 = Matrix([p1 - p0, p2 - p0]) m3 = Matrix([simplify(p1 - p0), simplify(p2 - p0)]) assert m1.rank(simplify=True) == 1 assert m2.rank(simplify=True) == 1 assert m3.rank(simplify=True) == 1 def test_as_real_imag(): m1 = Matrix(2,2,[1,2,3,4]) m2 = m1*S.ImaginaryUnit m3 = m1 + m2 for kls in classes: a,b = kls(m3).as_real_imag() assert list(a) == list(m1) assert list(b) == list(m1) def test_deprecated(): # Maintain tests for deprecated functions. We must capture # the deprecation warnings. When the deprecated functionality is # removed, the corresponding tests should be removed. m = Matrix(3, 3, [0, 1, 0, -4, 4, 0, -2, 1, 2]) P, Jcells = m.jordan_cells() assert Jcells[1] == Matrix(1, 1, [2]) assert Jcells[0] == Matrix(2, 2, [2, 1, 0, 2]) with warns_deprecated_sympy(): assert Matrix([[1,2],[3,4]]).dot(Matrix([[1,3],[4,5]])) == [10, 19, 14, 28] def test_issue_14489(): from sympy import Mod A = Matrix([-1, 1, 2]) B = Matrix([10, 20, -15]) assert Mod(A, 3) == Matrix([2, 1, 2]) assert Mod(B, 4) == Matrix([2, 0, 1]) def test_issue_14517(): M = Matrix([ [ 0, 10*I, 10*I, 0], [10*I, 0, 0, 10*I], [10*I, 0, 5 + 2*I, 10*I], [ 0, 10*I, 10*I, 5 + 2*I]]) ev = M.eigenvals() # test one random eigenvalue, the computation is a little slow test_ev = random.choice(list(ev.keys())) assert (M - test_ev*eye(4)).det() == 0 def test_issue_14943(): # Test that __array__ accepts the optional dtype argument try: from numpy import array except ImportError: skip('NumPy must be available to test creating matrices from ndarrays') M = Matrix([[1,2], [3,4]]) assert array(M, dtype=float).dtype.name == 'float64' def test_issue_8240(): # Eigenvalues of large triangular matrices n = 200 diagonal_variables = [Symbol('x%s' % i) for i in range(n)] M = [[0 for i in range(n)] for j in range(n)] for i in range(n): M[i][i] = diagonal_variables[i] M = Matrix(M) eigenvals = M.eigenvals() assert len(eigenvals) == n for i in range(n): assert eigenvals[diagonal_variables[i]] == 1 eigenvals = M.eigenvals(multiple=True) assert set(eigenvals) == set(diagonal_variables) # with multiplicity M = Matrix([[x, 0, 0], [1, y, 0], [2, 3, x]]) eigenvals = M.eigenvals() assert eigenvals == {x: 2, y: 1} eigenvals = M.eigenvals(multiple=True) assert len(eigenvals) == 3 assert eigenvals.count(x) == 2 assert eigenvals.count(y) == 1 def test_legacy_det(): # Minimal support for legacy keys for 'method' in det() # Partially copied from test_determinant() M = Matrix(( ( 3, -2, 0, 5), (-2, 1, -2, 2), ( 0, -2, 5, 0), ( 5, 0, 3, 4) )) assert M.det(method="bareis") == -289 assert M.det(method="det_lu") == -289 assert M.det(method="det_LU") == -289 M = Matrix(( (3, 2, 0, 0, 0), (0, 3, 2, 0, 0), (0, 0, 3, 2, 0), (0, 0, 0, 3, 2), (2, 0, 0, 0, 3) )) assert M.det(method="bareis") == 275 assert M.det(method="det_lu") == 275 assert M.det(method="Bareis") == 275 M = Matrix(( (1, 0, 1, 2, 12), (2, 0, 1, 1, 4), (2, 1, 1, -1, 3), (3, 2, -1, 1, 8), (1, 1, 1, 0, 6) )) assert M.det(method="bareis") == -55 assert M.det(method="det_lu") == -55 assert M.det(method="BAREISS") == -55 M = Matrix(( (-5, 2, 3, 4, 5), ( 1, -4, 3, 4, 5), ( 1, 2, -3, 4, 5), ( 1, 2, 3, -2, 5), ( 1, 2, 3, 4, -1) )) assert M.det(method="bareis") == 11664 assert M.det(method="det_lu") == 11664 assert M.det(method="BERKOWITZ") == 11664 M = Matrix(( ( 2, 7, -1, 3, 2), ( 0, 0, 1, 0, 1), (-2, 0, 7, 0, 2), (-3, -2, 4, 5, 3), ( 1, 0, 0, 0, 1) )) assert M.det(method="bareis") == 123 assert M.det(method="det_lu") == 123 assert M.det(method="LU") == 123

d27b60d162336cf52bd4c3e709a4e0f5b446f6d8167cac516f2f03c8263bd5f7

from sympy.matrices.expressions import MatrixExpr from sympy import MatrixBase class ElementwiseApplyFunction(MatrixExpr): r""" Apply function to a matrix elementwise without evaluating. Examples ======== >>> from sympy.matrices.expressions import MatrixSymbol >>> from sympy.matrices.expressions.applyfunc import ElementwiseApplyFunction >>> from sympy import exp >>> X = MatrixSymbol("X", 3, 3) >>> X.applyfunc(exp) ElementwiseApplyFunction(exp, X) >>> from sympy import eye >>> expr = ElementwiseApplyFunction(exp, eye(3)) >>> expr ElementwiseApplyFunction(exp, Matrix([ [1, 0, 0], [0, 1, 0], [0, 0, 1]])) >>> expr.doit() Matrix([ [E, 1, 1], [1, E, 1], [1, 1, E]]) Notice the difference with the real mathematical functions: >>> exp(eye(3)) Matrix([ [E, 0, 0], [0, E, 0], [0, 0, E]]) """ def __new__(cls, function, expr): obj = MatrixExpr.__new__(cls, function, expr) obj._function = function obj._expr = expr return obj @property def function(self): return self._function @property def expr(self): return self._expr @property def shape(self): return self.expr.shape def doit(self, **kwargs): deep = kwargs.get("deep", True) expr = self.expr if deep: expr = expr.doit(**kwargs) if isinstance(expr, MatrixBase): return expr.applyfunc(self.function) else: return self

ca1018abf5435bd0e28bf8cf0f576a176e375e33e1616fbbbfc099ab48d904bb

from __future__ import print_function, division from sympy.core.sympify import _sympify from sympy.core import S, Basic from sympy.matrices.expressions.matexpr import ShapeError from sympy.matrices.expressions.matpow import MatPow class Inverse(MatPow): """ The multiplicative inverse of a matrix expression This is a symbolic object that simply stores its argument without evaluating it. To actually compute the inverse, use the ``.inverse()`` method of matrices. Examples ======== >>> from sympy import MatrixSymbol, Inverse >>> A = MatrixSymbol('A', 3, 3) >>> B = MatrixSymbol('B', 3, 3) >>> Inverse(A) A**(-1) >>> A.inverse() == Inverse(A) True >>> (A*B).inverse() B**(-1)*A**(-1) >>> Inverse(A*B) (A*B)**(-1) """ is_Inverse = True exp = S(-1) def __new__(cls, mat, exp=S(-1)): # exp is there to make it consistent with # inverse.func(*inverse.args) == inverse mat = _sympify(mat) if not mat.is_Matrix: raise TypeError("mat should be a matrix") if not mat.is_square: raise ShapeError("Inverse of non-square matrix %s" % mat) return Basic.__new__(cls, mat, exp) @property def arg(self): return self.args[0] @property def shape(self): return self.arg.shape def _eval_inverse(self): return self.arg def _eval_determinant(self): from sympy.matrices.expressions.determinant import det return 1/det(self.arg) def doit(self, **hints): if 'inv_expand' in hints and hints['inv_expand'] == False: return self if hints.get('deep', True): return self.arg.doit(**hints).inverse() else: return self.arg.inverse() def _eval_derivative_matrix_lines(self, x): arg = self.args[0] lines = arg._eval_derivative_matrix_lines(x) for line in lines: if line.transposed: line.first *= self line.second *= -self.T else: line.first *= -self.T line.second *= self return lines from sympy.assumptions.ask import ask, Q from sympy.assumptions.refine import handlers_dict def refine_Inverse(expr, assumptions): """ >>> from sympy import MatrixSymbol, Q, assuming, refine >>> X = MatrixSymbol('X', 2, 2) >>> X.I X**(-1) >>> with assuming(Q.orthogonal(X)): ... print(refine(X.I)) X.T """ if ask(Q.orthogonal(expr), assumptions): return expr.arg.T elif ask(Q.unitary(expr), assumptions): return expr.arg.conjugate() elif ask(Q.singular(expr), assumptions): raise ValueError("Inverse of singular matrix %s" % expr.arg) return expr handlers_dict['Inverse'] = refine_Inverse

ef08ed0ffb603901a8de99625350ad432cda93da60d7015de9d7565575361ad1

from __future__ import print_function, division from sympy import Basic from sympy.functions import adjoint, conjugate from sympy.matrices.expressions.matexpr import MatrixExpr class Transpose(MatrixExpr): """ The transpose of a matrix expression. This is a symbolic object that simply stores its argument without evaluating it. To actually compute the transpose, use the ``transpose()`` function, or the ``.T`` attribute of matrices. Examples ======== >>> from sympy.matrices import MatrixSymbol, Transpose >>> from sympy.functions import transpose >>> A = MatrixSymbol('A', 3, 5) >>> B = MatrixSymbol('B', 5, 3) >>> Transpose(A) A.T >>> A.T == transpose(A) == Transpose(A) True >>> Transpose(A*B) (A*B).T >>> transpose(A*B) B.T*A.T """ is_Transpose = True def doit(self, **hints): arg = self.arg if hints.get('deep', True) and isinstance(arg, Basic): arg = arg.doit(**hints) try: result = arg._eval_transpose() return result if result is not None else Transpose(arg) except AttributeError: return Transpose(arg) @property def arg(self): return self.args[0] @property def shape(self): return self.arg.shape[::-1] def _entry(self, i, j, expand=False): return self.arg._entry(j, i, expand=expand) def _eval_adjoint(self): return conjugate(self.arg) def _eval_conjugate(self): return adjoint(self.arg) def _eval_transpose(self): return self.arg def _eval_trace(self): from .trace import Trace return Trace(self.arg) # Trace(X.T) => Trace(X) def _eval_determinant(self): from sympy.matrices.expressions.determinant import det return det(self.arg) def _eval_derivative_matrix_lines(self, x): lines = self.args[0]._eval_derivative_matrix_lines(x) return [i.transpose() for i in lines] def transpose(expr): """Matrix transpose""" return Transpose(expr).doit(deep=False) from sympy.assumptions.ask import ask, Q from sympy.assumptions.refine import handlers_dict def refine_Transpose(expr, assumptions): """ >>> from sympy import MatrixSymbol, Q, assuming, refine >>> X = MatrixSymbol('X', 2, 2) >>> X.T X.T >>> with assuming(Q.symmetric(X)): ... print(refine(X.T)) X """ if ask(Q.symmetric(expr), assumptions): return expr.arg return expr handlers_dict['Transpose'] = refine_Transpose

0137c28bf1080b2ada5981185a67320f23d829449d8a86eae9f0952051c7cb18

from __future__ import print_function, division from sympy import Number from sympy.core import Mul, Basic, sympify, Add from sympy.core.compatibility import range from sympy.functions import adjoint from sympy.matrices.expressions.transpose import transpose from sympy.strategies import (rm_id, unpack, typed, flatten, exhaust, do_one, new) from sympy.matrices.expressions.matexpr import (MatrixExpr, ShapeError, Identity, ZeroMatrix) from sympy.matrices.expressions.matpow import MatPow from sympy.matrices.matrices import MatrixBase class MatMul(MatrixExpr, Mul): """ A product of matrix expressions Examples ======== >>> from sympy import MatMul, MatrixSymbol >>> A = MatrixSymbol('A', 5, 4) >>> B = MatrixSymbol('B', 4, 3) >>> C = MatrixSymbol('C', 3, 6) >>> MatMul(A, B, C) A*B*C """ is_MatMul = True def __new__(cls, *args, **kwargs): check = kwargs.get('check', True) args = list(map(sympify, args)) obj = Basic.__new__(cls, *args) factor, matrices = obj.as_coeff_matrices() if check: validate(*matrices) if not matrices: return factor return obj @property def shape(self): matrices = [arg for arg in self.args if arg.is_Matrix] return (matrices[0].rows, matrices[-1].cols) def _entry(self, i, j, expand=True): from sympy import Dummy, Sum, Mul, ImmutableMatrix, Integer coeff, matrices = self.as_coeff_matrices() if len(matrices) == 1: # situation like 2*X, matmul is just X return coeff * matrices[0][i, j] indices = [None]*(len(matrices) + 1) ind_ranges = [None]*(len(matrices) - 1) indices[0] = i indices[-1] = j for i in range(1, len(matrices)): indices[i] = Dummy("i_%i" % i) for i, arg in enumerate(matrices[:-1]): ind_ranges[i] = arg.shape[1] - 1 matrices = [arg[indices[i], indices[i+1]] for i, arg in enumerate(matrices)] expr_in_sum = Mul.fromiter(matrices) if any(v.has(ImmutableMatrix) for v in matrices): expand = True result = coeff*Sum( expr_in_sum, *zip(indices[1:-1], [0]*len(ind_ranges), ind_ranges) ) # Don't waste time in result.doit() if the sum bounds are symbolic if not any(isinstance(v, (Integer, int)) for v in ind_ranges): expand = False return result.doit() if expand else result def as_coeff_matrices(self): scalars = [x for x in self.args if not x.is_Matrix] matrices = [x for x in self.args if x.is_Matrix] coeff = Mul(*scalars) return coeff, matrices def as_coeff_mmul(self): coeff, matrices = self.as_coeff_matrices() return coeff, MatMul(*matrices) def _eval_transpose(self): return MatMul(*[transpose(arg) for arg in self.args[::-1]]).doit() def _eval_adjoint(self): return MatMul(*[adjoint(arg) for arg in self.args[::-1]]).doit() def _eval_trace(self): factor, mmul = self.as_coeff_mmul() if factor != 1: from .trace import trace return factor * trace(mmul.doit()) else: raise NotImplementedError("Can't simplify any further") def _eval_determinant(self): from sympy.matrices.expressions.determinant import Determinant factor, matrices = self.as_coeff_matrices() square_matrices = only_squares(*matrices) return factor**self.rows * Mul(*list(map(Determinant, square_matrices))) def _eval_inverse(self): try: return MatMul(*[ arg.inverse() if isinstance(arg, MatrixExpr) else arg**-1 for arg in self.args[::-1]]).doit() except ShapeError: from sympy.matrices.expressions.inverse import Inverse return Inverse(self) def doit(self, **kwargs): deep = kwargs.get('deep', True) if deep: args = [arg.doit(**kwargs) for arg in self.args] else: args = self.args # treat scalar*MatrixSymbol or scalar*MatPow separately mats = [arg for arg in self.args if arg.is_Matrix] expr = canonicalize(MatMul(*args)) return expr # Needed for partial compatibility with Mul def args_cnc(self, **kwargs): coeff, matrices = self.as_coeff_matrices() # I don't know how coeff could have noncommutative factors, but this # handles it. coeff_c, coeff_nc = coeff.args_cnc(**kwargs) return coeff_c, coeff_nc + matrices def _eval_derivative_matrix_lines(self, x): from .transpose import Transpose with_x_ind = [i for i, arg in enumerate(self.args) if arg.has(x)] lines = [] for ind in with_x_ind: left_args = self.args[:ind] right_args = self.args[ind+1:] right_mat = MatMul.fromiter(right_args) right_rev = MatMul.fromiter([Transpose(i).doit() for i in reversed(right_args)]) left_mat = MatMul.fromiter(left_args) left_rev = MatMul.fromiter([Transpose(i).doit() for i in reversed(left_args)]) d = self.args[ind]._eval_derivative_matrix_lines(x) for i in d: if i.transposed: i.append_first(right_mat) i.append_second(left_rev) else: i.append_first(left_rev) i.append_second(right_mat) lines.append(i) return lines def validate(*matrices): """ Checks for valid shapes for args of MatMul """ for i in range(len(matrices)-1): A, B = matrices[i:i+2] if A.cols != B.rows: raise ShapeError("Matrices %s and %s are not aligned"%(A, B)) # Rules def newmul(*args): if args[0] == 1: args = args[1:] return new(MatMul, *args) def any_zeros(mul): if any([arg.is_zero or (arg.is_Matrix and arg.is_ZeroMatrix) for arg in mul.args]): matrices = [arg for arg in mul.args if arg.is_Matrix] return ZeroMatrix(matrices[0].rows, matrices[-1].cols) return mul def merge_explicit(matmul): """ Merge explicit MatrixBase arguments >>> from sympy import MatrixSymbol, eye, Matrix, MatMul, pprint >>> from sympy.matrices.expressions.matmul import merge_explicit >>> A = MatrixSymbol('A', 2, 2) >>> B = Matrix([[1, 1], [1, 1]]) >>> C = Matrix([[1, 2], [3, 4]]) >>> X = MatMul(A, B, C) >>> pprint(X) [1 1] [1 2] A*[ ]*[ ] [1 1] [3 4] >>> pprint(merge_explicit(X)) [4 6] A*[ ] [4 6] >>> X = MatMul(B, A, C) >>> pprint(X) [1 1] [1 2] [ ]*A*[ ] [1 1] [3 4] >>> pprint(merge_explicit(X)) [1 1] [1 2] [ ]*A*[ ] [1 1] [3 4] """ if not any(isinstance(arg, MatrixBase) for arg in matmul.args): return matmul newargs = [] last = matmul.args[0] for arg in matmul.args[1:]: if isinstance(arg, (MatrixBase, Number)) and isinstance(last, (MatrixBase, Number)): last = last * arg else: newargs.append(last) last = arg newargs.append(last) return MatMul(*newargs) def xxinv(mul): """ Y * X * X.I -> Y """ from sympy.matrices.expressions.inverse import Inverse factor, matrices = mul.as_coeff_matrices() for i, (X, Y) in enumerate(zip(matrices[:-1], matrices[1:])): try: if X.is_square and Y.is_square: _X, x_exp = X, 1 _Y, y_exp = Y, 1 if isinstance(X, MatPow) and not isinstance(X, Inverse): _X, x_exp = X.args if isinstance(Y, MatPow) and not isinstance(Y, Inverse): _Y, y_exp = Y.args if _X == _Y.inverse(): if x_exp - y_exp > 0: I = _X**(x_exp-y_exp) else: I = _Y**(y_exp-x_exp) return newmul(factor, *(matrices[:i] + [I] + matrices[i+2:])) except ValueError: # Y might not be invertible pass return mul def remove_ids(mul): """ Remove Identities from a MatMul This is a modified version of sympy.strategies.rm_id. This is necesssary because MatMul may contain both MatrixExprs and Exprs as args. See Also ======== sympy.strategies.rm_id """ # Separate Exprs from MatrixExprs in args factor, mmul = mul.as_coeff_mmul() # Apply standard rm_id for MatMuls result = rm_id(lambda x: x.is_Identity is True)(mmul) if result != mmul: return newmul(factor, *result.args) # Recombine and return else: return mul def factor_in_front(mul): factor, matrices = mul.as_coeff_matrices() if factor != 1: return newmul(factor, *matrices) return mul def combine_powers(mul): # combine consecutive powers with the same base into one # e.g. A*A**2 -> A**3 from sympy.matrices.expressions import MatPow factor, mmul = mul.as_coeff_mmul() args = [] base = None exp = 0 for arg in mmul.args: if isinstance(arg, MatPow): current_base = arg.args[0] current_exp = arg.args[1] else: current_base = arg current_exp = 1 if current_base == base: exp += current_exp else: if not base is None: if exp == 1: args.append(base) else: args.append(base**exp) exp = current_exp base = current_base if exp == 1: args.append(base) else: args.append(base**exp) return newmul(factor, *args) rules = (any_zeros, remove_ids, xxinv, unpack, rm_id(lambda x: x == 1), merge_explicit, factor_in_front, flatten, combine_powers) canonicalize = exhaust(typed({MatMul: do_one(*rules)})) def only_squares(*matrices): """factor matrices only if they are square""" if matrices[0].rows != matrices[-1].cols: raise RuntimeError("Invalid matrices being multiplied") out = [] start = 0 for i, M in enumerate(matrices): if M.cols == matrices[start].rows: out.append(MatMul(*matrices[start:i+1]).doit()) start = i+1 return out from sympy.assumptions.ask import ask, Q from sympy.assumptions.refine import handlers_dict def refine_MatMul(expr, assumptions): """ >>> from sympy import MatrixSymbol, Q, assuming, refine >>> X = MatrixSymbol('X', 2, 2) >>> expr = X * X.T >>> print(expr) X*X.T >>> with assuming(Q.orthogonal(X)): ... print(refine(expr)) I """ newargs = [] exprargs = [] for args in expr.args: if args.is_Matrix: exprargs.append(args) else: newargs.append(args) last = exprargs[0] for arg in exprargs[1:]: if arg == last.T and ask(Q.orthogonal(arg), assumptions): last = Identity(arg.shape[0]) elif arg == last.conjugate() and ask(Q.unitary(arg), assumptions): last = Identity(arg.shape[0]) else: newargs.append(last) last = arg newargs.append(last) return MatMul(*newargs) handlers_dict['MatMul'] = refine_MatMul

115e647f64a86f161c642aabef3f8772a4eeadd4c5b8613e95012f33975f7e15

from __future__ import print_function, division from .matexpr import MatrixExpr, ShapeError, Identity, ZeroMatrix from .transpose import Transpose from sympy.core.sympify import _sympify from sympy.core.compatibility import range from sympy.matrices import MatrixBase from sympy.core import S, Basic class MatPow(MatrixExpr): def __new__(cls, base, exp): base = _sympify(base) if not base.is_Matrix: raise TypeError("Function parameter should be a matrix") exp = _sympify(exp) return super(MatPow, cls).__new__(cls, base, exp) @property def base(self): return self.args[0] @property def exp(self): return self.args[1] @property def shape(self): return self.base.shape def _entry(self, i, j, **kwargs): from sympy.matrices.expressions import MatMul A = self.doit() if isinstance(A, MatPow): # We still have a MatPow, make an explicit MatMul out of it. if not A.base.is_square: raise ShapeError("Power of non-square matrix %s" % A.base) elif A.exp.is_Integer and A.exp.is_positive: A = MatMul(*[A.base for k in range(A.exp)]) #elif A.exp.is_Integer and self.exp.is_negative: # Note: possible future improvement: in principle we can take # positive powers of the inverse, but carefully avoid recursion, # perhaps by adding `_entry` to Inverse (as it is our subclass). # T = A.base.as_explicit().inverse() # A = MatMul(*[T for k in range(-A.exp)]) else: # Leave the expression unevaluated: from sympy.matrices.expressions.matexpr import MatrixElement return MatrixElement(self, i, j) return A._entry(i, j) def doit(self, **kwargs): from sympy.matrices.expressions import Inverse deep = kwargs.get('deep', True) if deep: args = [arg.doit(**kwargs) for arg in self.args] else: args = self.args base, exp = args # combine all powers, e.g. (A**2)**3 = A**6 while isinstance(base, MatPow): exp = exp*base.args[1] base = base.args[0] if exp.is_zero and base.is_square: if isinstance(base, MatrixBase): return base.func(Identity(base.shape[0])) return Identity(base.shape[0]) elif isinstance(base, ZeroMatrix) and exp.is_negative: raise ValueError("Matrix determinant is 0, not invertible.") elif isinstance(base, (Identity, ZeroMatrix)): return base elif isinstance(base, MatrixBase) and exp.is_number: if exp is S.One: return base return base**exp # Note: just evaluate cases we know, return unevaluated on others. # E.g., MatrixSymbol('x', n, m) to power 0 is not an error. elif exp is S(-1) and base.is_square: return Inverse(base).doit(**kwargs) elif exp is S.One: return base return MatPow(base, exp) def _eval_transpose(self): base, exp = self.args return MatPow(base.T, exp) def _eval_derivative_matrix_lines(self, x): from .matmul import MatMul exp = self.exp if (exp > 0) == True: newexpr = MatMul.fromiter([self.base for i in range(exp)]) elif (exp == -1) == True: return Inverse(self.base)._eval_derivative_matrix_lines(x) elif (exp < 0) == True: newexpr = MatMul.fromiter([Inverse(self.base) for i in range(-exp)]) elif (exp == 0) == True: return self.doit()._eval_derivative_matrix_lines(x) else: raise NotImplementedError("cannot evaluate %s derived by %s" % (self, x)) return newexpr._eval_derivative_matrix_lines(x)

1efd7be8d555fbbb531e38561e8e80a402d59d8df75f800704cfa8edf3dcf7e2

from __future__ import print_function, division from functools import wraps, reduce import collections from sympy.core import S, Symbol, Tuple, Integer, Basic, Expr, Eq from sympy.core.decorators import call_highest_priority from sympy.core.compatibility import range, SYMPY_INTS, default_sort_key from sympy.core.sympify import SympifyError, sympify from sympy.functions import conjugate, adjoint from sympy.functions.special.tensor_functions import KroneckerDelta from sympy.matrices import ShapeError from sympy.simplify import simplify from sympy.utilities.misc import filldedent def _sympifyit(arg, retval=None): # This version of _sympifyit sympifies MutableMatrix objects def deco(func): @wraps(func) def __sympifyit_wrapper(a, b): try: b = sympify(b, strict=True) return func(a, b) except SympifyError: return retval return __sympifyit_wrapper return deco class MatrixExpr(Expr): """Superclass for Matrix Expressions MatrixExprs represent abstract matrices, linear transformations represented within a particular basis. Examples ======== >>> from sympy import MatrixSymbol >>> A = MatrixSymbol('A', 3, 3) >>> y = MatrixSymbol('y', 3, 1) >>> x = (A.T*A).I * A * y See Also ======== MatrixSymbol, MatAdd, MatMul, Transpose, Inverse """ # Should not be considered iterable by the # sympy.core.compatibility.iterable function. Subclass that actually are # iterable (i.e., explicit matrices) should set this to True. _iterable = False _op_priority = 11.0 is_Matrix = True is_MatrixExpr = True is_Identity = None is_Inverse = False is_Transpose = False is_ZeroMatrix = False is_MatAdd = False is_MatMul = False is_commutative = False is_number = False is_symbol = False def __new__(cls, *args, **kwargs): args = map(sympify, args) return Basic.__new__(cls, *args, **kwargs) # The following is adapted from the core Expr object def __neg__(self): return MatMul(S.NegativeOne, self).doit() def __abs__(self): raise NotImplementedError @_sympifyit('other', NotImplemented) @call_highest_priority('__radd__') def __add__(self, other): return MatAdd(self, other, check=True).doit() @_sympifyit('other', NotImplemented) @call_highest_priority('__add__') def __radd__(self, other): return MatAdd(other, self, check=True).doit() @_sympifyit('other', NotImplemented) @call_highest_priority('__rsub__') def __sub__(self, other): return MatAdd(self, -other, check=True).doit() @_sympifyit('other', NotImplemented) @call_highest_priority('__sub__') def __rsub__(self, other): return MatAdd(other, -self, check=True).doit() @_sympifyit('other', NotImplemented) @call_highest_priority('__rmul__') def __mul__(self, other): return MatMul(self, other).doit() @_sympifyit('other', NotImplemented) @call_highest_priority('__rmul__') def __matmul__(self, other): return MatMul(self, other).doit() @_sympifyit('other', NotImplemented) @call_highest_priority('__mul__') def __rmul__(self, other): return MatMul(other, self).doit() @_sympifyit('other', NotImplemented) @call_highest_priority('__mul__') def __rmatmul__(self, other): return MatMul(other, self).doit() @_sympifyit('other', NotImplemented) @call_highest_priority('__rpow__') def __pow__(self, other): if not self.is_square: raise ShapeError("Power of non-square matrix %s" % self) elif self.is_Identity: return self elif other is S.Zero: return Identity(self.rows) elif other is S.One: return self return MatPow(self, other).doit(deep=False) @_sympifyit('other', NotImplemented) @call_highest_priority('__pow__') def __rpow__(self, other): raise NotImplementedError("Matrix Power not defined") @_sympifyit('other', NotImplemented) @call_highest_priority('__rdiv__') def __div__(self, other): return self * other**S.NegativeOne @_sympifyit('other', NotImplemented) @call_highest_priority('__div__') def __rdiv__(self, other): raise NotImplementedError() #return MatMul(other, Pow(self, S.NegativeOne)) __truediv__ = __div__ __rtruediv__ = __rdiv__ @property def rows(self): return self.shape[0] @property def cols(self): return self.shape[1] @property def is_square(self): return self.rows == self.cols def _eval_conjugate(self): from sympy.matrices.expressions.adjoint import Adjoint from sympy.matrices.expressions.transpose import Transpose return Adjoint(Transpose(self)) def as_real_imag(self): from sympy import I real = (S(1)/2) * (self + self._eval_conjugate()) im = (self - self._eval_conjugate())/(2*I) return (real, im) def _eval_inverse(self): from sympy.matrices.expressions.inverse import Inverse return Inverse(self) def _eval_transpose(self): return Transpose(self) def _eval_power(self, exp): return MatPow(self, exp) def _eval_simplify(self, **kwargs): if self.is_Atom: return self else: return self.__class__(*[simplify(x, **kwargs) for x in self.args]) def _eval_adjoint(self): from sympy.matrices.expressions.adjoint import Adjoint return Adjoint(self) def _eval_derivative(self, x): return _matrix_derivative(self, x) def _eval_derivative_n_times(self, x, n): return Basic._eval_derivative_n_times(self, x, n) def _entry(self, i, j, **kwargs): raise NotImplementedError( "Indexing not implemented for %s" % self.__class__.__name__) def adjoint(self): return adjoint(self) def as_coeff_Mul(self, rational=False): """Efficiently extract the coefficient of a product. """ return S.One, self def conjugate(self): return conjugate(self) def transpose(self): from sympy.matrices.expressions.transpose import transpose return transpose(self) T = property(transpose, None, None, 'Matrix transposition.') def inverse(self): return self._eval_inverse() inv = inverse @property def I(self): return self.inverse() def valid_index(self, i, j): def is_valid(idx): return isinstance(idx, (int, Integer, Symbol, Expr)) return (is_valid(i) and is_valid(j) and (self.rows is None or (0 <= i) != False and (i < self.rows) != False) and (0 <= j) != False and (j < self.cols) != False) def __getitem__(self, key): if not isinstance(key, tuple) and isinstance(key, slice): from sympy.matrices.expressions.slice import MatrixSlice return MatrixSlice(self, key, (0, None, 1)) if isinstance(key, tuple) and len(key) == 2: i, j = key if isinstance(i, slice) or isinstance(j, slice): from sympy.matrices.expressions.slice import MatrixSlice return MatrixSlice(self, i, j) i, j = sympify(i), sympify(j) if self.valid_index(i, j) != False: return self._entry(i, j) else: raise IndexError("Invalid indices (%s, %s)" % (i, j)) elif isinstance(key, (SYMPY_INTS, Integer)): # row-wise decomposition of matrix rows, cols = self.shape # allow single indexing if number of columns is known if not isinstance(cols, Integer): raise IndexError(filldedent(''' Single indexing is only supported when the number of columns is known.''')) key = sympify(key) i = key // cols j = key % cols if self.valid_index(i, j) != False: return self._entry(i, j) else: raise IndexError("Invalid index %s" % key) elif isinstance(key, (Symbol, Expr)): raise IndexError(filldedent(''' Only integers may be used when addressing the matrix with a single index.''')) raise IndexError("Invalid index, wanted %s[i,j]" % self) def as_explicit(self): """ Returns a dense Matrix with elements represented explicitly Returns an object of type ImmutableDenseMatrix. Examples ======== >>> from sympy import Identity >>> I = Identity(3) >>> I I >>> I.as_explicit() Matrix([ [1, 0, 0], [0, 1, 0], [0, 0, 1]]) See Also ======== as_mutable: returns mutable Matrix type """ from sympy.matrices.immutable import ImmutableDenseMatrix return ImmutableDenseMatrix([[ self[i, j] for j in range(self.cols)] for i in range(self.rows)]) def as_mutable(self): """ Returns a dense, mutable matrix with elements represented explicitly Examples ======== >>> from sympy import Identity >>> I = Identity(3) >>> I I >>> I.shape (3, 3) >>> I.as_mutable() Matrix([ [1, 0, 0], [0, 1, 0], [0, 0, 1]]) See Also ======== as_explicit: returns ImmutableDenseMatrix """ return self.as_explicit().as_mutable() def __array__(self): from numpy import empty a = empty(self.shape, dtype=object) for i in range(self.rows): for j in range(self.cols): a[i, j] = self[i, j] return a def equals(self, other): """ Test elementwise equality between matrices, potentially of different types >>> from sympy import Identity, eye >>> Identity(3).equals(eye(3)) True """ return self.as_explicit().equals(other) def canonicalize(self): return self def as_coeff_mmul(self): return 1, MatMul(self) @staticmethod def from_index_summation(expr, first_index=None, last_index=None, dimensions=None): r""" Parse expression of matrices with explicitly summed indices into a matrix expression without indices, if possible. This transformation expressed in mathematical notation: `\sum_{j=0}^{N-1} A_{i,j} B_{j,k} \Longrightarrow \mathbf{A}\cdot \mathbf{B}` Optional parameter ``first_index``: specify which free index to use as the index starting the expression. Examples ======== >>> from sympy import MatrixSymbol, MatrixExpr, Sum, Symbol >>> from sympy.abc import i, j, k, l, N >>> A = MatrixSymbol("A", N, N) >>> B = MatrixSymbol("B", N, N) >>> expr = Sum(A[i, j]*B[j, k], (j, 0, N-1)) >>> MatrixExpr.from_index_summation(expr) A*B Transposition is detected: >>> expr = Sum(A[j, i]*B[j, k], (j, 0, N-1)) >>> MatrixExpr.from_index_summation(expr) A.T*B Detect the trace: >>> expr = Sum(A[i, i], (i, 0, N-1)) >>> MatrixExpr.from_index_summation(expr) Trace(A) More complicated expressions: >>> expr = Sum(A[i, j]*B[k, j]*A[l, k], (j, 0, N-1), (k, 0, N-1)) >>> MatrixExpr.from_index_summation(expr) A*B.T*A.T """ from sympy import Sum, Mul, Add, MatMul, transpose, trace from sympy.strategies.traverse import bottom_up def remove_matelement(expr, i1, i2): def repl_match(pos): def func(x): if not isinstance(x, MatrixElement): return False if x.args[pos] != i1: return False if x.args[3-pos] == 0: if x.args[0].shape[2-pos] == 1: return True else: return False return True return func expr = expr.replace(repl_match(1), lambda x: x.args[0]) expr = expr.replace(repl_match(2), lambda x: transpose(x.args[0])) # Make sure that all Mul are transformed to MatMul and that they # are flattened: rule = bottom_up(lambda x: reduce(lambda a, b: a*b, x.args) if isinstance(x, (Mul, MatMul)) else x) return rule(expr) def recurse_expr(expr, index_ranges={}): if expr.is_Mul: nonmatargs = [] pos_arg = [] pos_ind = [] dlinks = {} link_ind = [] counter = 0 args_ind = [] for arg in expr.args: retvals = recurse_expr(arg, index_ranges) assert isinstance(retvals, list) if isinstance(retvals, list): for i in retvals: args_ind.append(i) else: args_ind.append(retvals) for arg_symbol, arg_indices in args_ind: if arg_indices is None: nonmatargs.append(arg_symbol) continue if isinstance(arg_symbol, MatrixElement): arg_symbol = arg_symbol.args[0] pos_arg.append(arg_symbol) pos_ind.append(arg_indices) link_ind.append([None]*len(arg_indices)) for i, ind in enumerate(arg_indices): if ind in dlinks: other_i = dlinks[ind] link_ind[counter][i] = other_i link_ind[other_i[0]][other_i[1]] = (counter, i) dlinks[ind] = (counter, i) counter += 1 counter2 = 0 lines = {} while counter2 < len(link_ind): for i, e in enumerate(link_ind): if None in e: line_start_index = (i, e.index(None)) break cur_ind_pos = line_start_index cur_line = [] index1 = pos_ind[cur_ind_pos[0]][cur_ind_pos[1]] while True: d, r = cur_ind_pos if pos_arg[d] != 1: if r % 2 == 1: cur_line.append(transpose(pos_arg[d])) else: cur_line.append(pos_arg[d]) next_ind_pos = link_ind[d][1-r] counter2 += 1 # Mark as visited, there will be no `None` anymore: link_ind[d] = (-1, -1) if next_ind_pos is None: index2 = pos_ind[d][1-r] lines[(index1, index2)] = cur_line break cur_ind_pos = next_ind_pos ret_indices = list(j for i in lines for j in i) lines = {k: MatMul.fromiter(v) if len(v) != 1 else v[0] for k, v in lines.items()} return [(Mul.fromiter(nonmatargs), None)] + [ (MatrixElement(a, i, j), (i, j)) for (i, j), a in lines.items() ] elif expr.is_Add: res = [recurse_expr(i) for i in expr.args] d = collections.defaultdict(list) for res_addend in res: scalar = 1 for elem, indices in res_addend: if indices is None: scalar = elem continue indices = tuple(sorted(indices, key=default_sort_key)) d[indices].append(scalar*remove_matelement(elem, *indices)) scalar = 1 return [(MatrixElement(Add.fromiter(v), *k), k) for k, v in d.items()] elif isinstance(expr, KroneckerDelta): i1, i2 = expr.args if dimensions is not None: identity = Identity(dimensions[0]) else: identity = S.One return [(MatrixElement(identity, i1, i2), (i1, i2))] elif isinstance(expr, MatrixElement): matrix_symbol, i1, i2 = expr.args if i1 in index_ranges: r1, r2 = index_ranges[i1] if r1 != 0 or matrix_symbol.shape[0] != r2+1: raise ValueError("index range mismatch: {0} vs. (0, {1})".format( (r1, r2), matrix_symbol.shape[0])) if i2 in index_ranges: r1, r2 = index_ranges[i2] if r1 != 0 or matrix_symbol.shape[1] != r2+1: raise ValueError("index range mismatch: {0} vs. (0, {1})".format( (r1, r2), matrix_symbol.shape[1])) if (i1 == i2) and (i1 in index_ranges): return [(trace(matrix_symbol), None)] return [(MatrixElement(matrix_symbol, i1, i2), (i1, i2))] elif isinstance(expr, Sum): return recurse_expr( expr.args[0], index_ranges={i[0]: i[1:] for i in expr.args[1:]} ) else: return [(expr, None)] retvals = recurse_expr(expr) factors, indices = zip(*retvals) retexpr = Mul.fromiter(factors) if len(indices) == 0 or list(set(indices)) == [None]: return retexpr if first_index is None: for i in indices: if i is not None: ind0 = i break return remove_matelement(retexpr, *ind0) else: return remove_matelement(retexpr, first_index, last_index) def applyfunc(self, func): from .applyfunc import ElementwiseApplyFunction return ElementwiseApplyFunction(func, self) def _matrix_derivative(expr, x): from sympy import Derivative lines = expr._eval_derivative_matrix_lines(x) first = lines[0].first second = lines[0].second higher = lines[0].higher ranks = [i.rank() for i in lines] assert len(set(ranks)) == 1 rank = ranks[0] if rank <= 2: return reduce(lambda x, y: x+y, [i.matrix_form() for i in lines]) if first != 1: return reduce(lambda x,y: x+y, [lr.first * lr.second.T for lr in lines]) elif higher != 1: return reduce(lambda x,y: x+y, [lr.higher for lr in lines]) return Derivative(expr, x) class MatrixElement(Expr): parent = property(lambda self: self.args[0]) i = property(lambda self: self.args[1]) j = property(lambda self: self.args[2]) _diff_wrt = True is_symbol = True is_commutative = True def __new__(cls, name, n, m): n, m = map(sympify, (n, m)) from sympy import MatrixBase if isinstance(name, (MatrixBase,)): if n.is_Integer and m.is_Integer: return name[n, m] name = sympify(name) obj = Expr.__new__(cls, name, n, m) return obj def doit(self, **kwargs): deep = kwargs.get('deep', True) if deep: args = [arg.doit(**kwargs) for arg in self.args] else: args = self.args return args[0][args[1], args[2]] @property def indices(self): return self.args[1:] def _eval_derivative(self, v): from sympy import Sum, symbols, Dummy if not isinstance(v, MatrixElement): from sympy import MatrixBase if isinstance(self.parent, MatrixBase): return self.parent.diff(v)[self.i, self.j] return S.Zero M = self.args[0] if M == v.args[0]: return KroneckerDelta(self.args[1], v.args[1])*KroneckerDelta(self.args[2], v.args[2]) if isinstance(M, Inverse): i, j = self.args[1:] i1, i2 = symbols("z1, z2", cls=Dummy) Y = M.args[0] r1, r2 = Y.shape return -Sum(M[i, i1]*Y[i1, i2].diff(v)*M[i2, j], (i1, 0, r1-1), (i2, 0, r2-1)) if self.has(v.args[0]): return None return S.Zero class MatrixSymbol(MatrixExpr): """Symbolic representation of a Matrix object Creates a SymPy Symbol to represent a Matrix. This matrix has a shape and can be included in Matrix Expressions Examples ======== >>> from sympy import MatrixSymbol, Identity >>> A = MatrixSymbol('A', 3, 4) # A 3 by 4 Matrix >>> B = MatrixSymbol('B', 4, 3) # A 4 by 3 Matrix >>> A.shape (3, 4) >>> 2*A*B + Identity(3) I + 2*A*B """ is_commutative = False is_symbol = True _diff_wrt = True def __new__(cls, name, n, m): n, m = sympify(n), sympify(m) obj = Basic.__new__(cls, name, n, m) return obj def _hashable_content(self): return (self.name, self.shape) @property def shape(self): return self.args[1:3] @property def name(self): return self.args[0] def _eval_subs(self, old, new): # only do substitutions in shape shape = Tuple(*self.shape)._subs(old, new) return MatrixSymbol(self.name, *shape) def __call__(self, *args): raise TypeError("%s object is not callable" % self.__class__) def _entry(self, i, j, **kwargs): return MatrixElement(self, i, j) @property def free_symbols(self): return set((self,)) def doit(self, **hints): if hints.get('deep', True): return type(self)(self.name, self.args[1].doit(**hints), self.args[2].doit(**hints)) else: return self def _eval_simplify(self, **kwargs): return self def _eval_derivative_matrix_lines(self, x): if self != x: return [_LeftRightArgs( ZeroMatrix(x.shape[0], self.shape[0]), ZeroMatrix(x.shape[1], self.shape[1]), transposed=False, )] else: first=Identity(self.shape[0]) second=Identity(self.shape[1]) return [_LeftRightArgs( first=first, second=second, transposed=False, )] class Identity(MatrixExpr): """The Matrix Identity I - multiplicative identity Examples ======== >>> from sympy.matrices import Identity, MatrixSymbol >>> A = MatrixSymbol('A', 3, 5) >>> I = Identity(3) >>> I*A A """ is_Identity = True def __new__(cls, n): return super(Identity, cls).__new__(cls, sympify(n)) @property def rows(self): return self.args[0] @property def cols(self): return self.args[0] @property def shape(self): return (self.args[0], self.args[0]) def _eval_transpose(self): return self def _eval_trace(self): return self.rows def _eval_inverse(self): return self def conjugate(self): return self def _entry(self, i, j, **kwargs): eq = Eq(i, j) if eq is S.true: return S.One elif eq is S.false: return S.Zero return KroneckerDelta(i, j) def _eval_determinant(self): return S.One class ZeroMatrix(MatrixExpr): """The Matrix Zero 0 - additive identity Examples ======== >>> from sympy import MatrixSymbol, ZeroMatrix >>> A = MatrixSymbol('A', 3, 5) >>> Z = ZeroMatrix(3, 5) >>> A + Z A >>> Z*A.T 0 """ is_ZeroMatrix = True def __new__(cls, m, n): return super(ZeroMatrix, cls).__new__(cls, m, n) @property def shape(self): return (self.args[0], self.args[1]) @_sympifyit('other', NotImplemented) @call_highest_priority('__rpow__') def __pow__(self, other): if other != 1 and not self.is_square: raise ShapeError("Power of non-square matrix %s" % self) if other == 0: return Identity(self.rows) if other < 1: raise ValueError("Matrix det == 0; not invertible.") return self def _eval_transpose(self): return ZeroMatrix(self.cols, self.rows) def _eval_trace(self): return S.Zero def _eval_determinant(self): return S.Zero def conjugate(self): return self def _entry(self, i, j, **kwargs): return S.Zero def __nonzero__(self): return False __bool__ = __nonzero__ def matrix_symbols(expr): return [sym for sym in expr.free_symbols if sym.is_Matrix] class _LeftRightArgs(object): r""" Helper class to compute matrix derivatives. The logic: when an expression is derived by a matrix `X_{mn}`, two lines of matrix multiplications are created: the one contracted to `m` (first line), and the one contracted to `n` (second line). Transposition flips the side by which new matrices are connected to the lines. The trace connects the end of the two lines. """ def __init__(self, first, second, higher=S.One, transposed=False): self.first = first self.second = second self.higher = higher self.transposed = transposed def __repr__(self): return "_LeftRightArgs(first=%s[%s], second=%s[%s], higher=%s, transposed=%s)" % ( self.first, self.first.shape if isinstance(self.first, MatrixExpr) else None, self.second, self.second.shape if isinstance(self.second, MatrixExpr) else None, self.higher, self.transposed, ) def transpose(self): self.transposed = not self.transposed return self def matrix_form(self): if self.first != 1 and self.higher != 1: raise ValueError("higher dimensional array cannot be represented") if self.first != 1: return self.first*self.second.T else: return self.higher def rank(self): """ Number of dimensions different from trivial (warning: not related to matrix rank). """ rank = 0 if self.first != 1: rank += sum([i != 1 for i in self.first.shape]) if self.second != 1: rank += sum([i != 1 for i in self.second.shape]) if self.higher != 1: rank += 2 return rank def append_first(self, other): self.first *= other def append_second(self, other): self.second *= other def __hash__(self): return hash((self.first, self.second, self.transposed)) def __eq__(self, other): if not isinstance(other, _LeftRightArgs): return False return (self.first == other.first) and (self.second == other.second) and (self.transposed == other.transposed) from .matmul import MatMul from .matadd import MatAdd from .matpow import MatPow from .transpose import Transpose from .inverse import Inverse

b0ec35a24973f5c27340cd80789f8ec7fb19756d8e10ff7a56e0621272d11c5d

"""Implementation of the Kronecker product""" from __future__ import division, print_function from sympy.core import Add, Mul, Pow, prod, sympify from sympy.core.compatibility import range from sympy.functions import adjoint from sympy.matrices.expressions.matexpr import MatrixExpr, ShapeError, Identity from sympy.matrices.expressions.transpose import transpose from sympy.matrices.matrices import MatrixBase from sympy.strategies import ( canon, condition, distribute, do_one, exhaust, flatten, typed, unpack) from sympy.strategies.traverse import bottom_up from sympy.utilities import sift from .matadd import MatAdd from .matmul import MatMul from .matpow import MatPow def kronecker_product(*matrices): """ The Kronecker product of two or more arguments. This computes the explicit Kronecker product for subclasses of ``MatrixBase`` i.e. explicit matrices. Otherwise, a symbolic ``KroneckerProduct`` object is returned. Examples ======== For ``MatrixSymbol`` arguments a ``KroneckerProduct`` object is returned. Elements of this matrix can be obtained by indexing, or for MatrixSymbols with known dimension the explicit matrix can be obtained with ``.as_explicit()`` >>> from sympy.matrices import kronecker_product, MatrixSymbol >>> A = MatrixSymbol('A', 2, 2) >>> B = MatrixSymbol('B', 2, 2) >>> kronecker_product(A) A >>> kronecker_product(A, B) KroneckerProduct(A, B) >>> kronecker_product(A, B)[0, 1] A[0, 0]*B[0, 1] >>> kronecker_product(A, B).as_explicit() Matrix([ [A[0, 0]*B[0, 0], A[0, 0]*B[0, 1], A[0, 1]*B[0, 0], A[0, 1]*B[0, 1]], [A[0, 0]*B[1, 0], A[0, 0]*B[1, 1], A[0, 1]*B[1, 0], A[0, 1]*B[1, 1]], [A[1, 0]*B[0, 0], A[1, 0]*B[0, 1], A[1, 1]*B[0, 0], A[1, 1]*B[0, 1]], [A[1, 0]*B[1, 0], A[1, 0]*B[1, 1], A[1, 1]*B[1, 0], A[1, 1]*B[1, 1]]]) For explicit matrices the Kronecker product is returned as a Matrix >>> from sympy.matrices import Matrix, kronecker_product >>> sigma_x = Matrix([ ... [0, 1], ... [1, 0]]) ... >>> Isigma_y = Matrix([ ... [0, 1], ... [-1, 0]]) ... >>> kronecker_product(sigma_x, Isigma_y) Matrix([ [ 0, 0, 0, 1], [ 0, 0, -1, 0], [ 0, 1, 0, 0], [-1, 0, 0, 0]]) See Also ======== KroneckerProduct """ if not matrices: raise TypeError("Empty Kronecker product is undefined") validate(*matrices) if len(matrices) == 1: return matrices[0] else: return KroneckerProduct(*matrices).doit() class KroneckerProduct(MatrixExpr): """ The Kronecker product of two or more arguments. The Kronecker product is a non-commutative product of matrices. Given two matrices of dimension (m, n) and (s, t) it produces a matrix of dimension (m s, n t). This is a symbolic object that simply stores its argument without evaluating it. To actually compute the product, use the function ``kronecker_product()`` or call the the ``.doit()`` or ``.as_explicit()`` methods. >>> from sympy.matrices import KroneckerProduct, MatrixSymbol >>> A = MatrixSymbol('A', 5, 5) >>> B = MatrixSymbol('B', 5, 5) >>> isinstance(KroneckerProduct(A, B), KroneckerProduct) True """ is_KroneckerProduct = True def __new__(cls, *args, **kwargs): args = list(map(sympify, args)) if all(a.is_Identity for a in args): ret = Identity(prod(a.rows for a in args)) if all(isinstance(a, MatrixBase) for a in args): return ret.as_explicit() else: return ret check = kwargs.get('check', True) if check: validate(*args) return super(KroneckerProduct, cls).__new__(cls, *args) @property def shape(self): rows, cols = self.args[0].shape for mat in self.args[1:]: rows *= mat.rows cols *= mat.cols return (rows, cols) def _entry(self, i, j): result = 1 for mat in reversed(self.args): i, m = divmod(i, mat.rows) j, n = divmod(j, mat.cols) result *= mat[m, n] return result def _eval_adjoint(self): return KroneckerProduct(*list(map(adjoint, self.args))).doit() def _eval_conjugate(self): return KroneckerProduct(*[a.conjugate() for a in self.args]).doit() def _eval_transpose(self): return KroneckerProduct(*list(map(transpose, self.args))).doit() def _eval_trace(self): from .trace import trace return prod(trace(a) for a in self.args) def _eval_determinant(self): from .determinant import det, Determinant if not all(a.is_square for a in self.args): return Determinant(self) m = self.rows return prod(det(a)**(m/a.rows) for a in self.args) def _eval_inverse(self): try: return KroneckerProduct(*[a.inverse() for a in self.args]) except ShapeError: from sympy.matrices.expressions.inverse import Inverse return Inverse(self) def structurally_equal(self, other): '''Determine whether two matrices have the same Kronecker product structure Examples ======== >>> from sympy import KroneckerProduct, MatrixSymbol, symbols >>> m, n = symbols(r'm, n', integer=True) >>> A = MatrixSymbol('A', m, m) >>> B = MatrixSymbol('B', n, n) >>> C = MatrixSymbol('C', m, m) >>> D = MatrixSymbol('D', n, n) >>> KroneckerProduct(A, B).structurally_equal(KroneckerProduct(C, D)) True >>> KroneckerProduct(A, B).structurally_equal(KroneckerProduct(D, C)) False >>> KroneckerProduct(A, B).structurally_equal(C) False ''' # Inspired by BlockMatrix return (isinstance(other, KroneckerProduct) and self.shape == other.shape and len(self.args) == len(other.args) and all(a.shape == b.shape for (a, b) in zip(self.args, other.args))) def has_matching_shape(self, other): '''Determine whether two matrices have the appropriate structure to bring matrix multiplication inside the KroneckerProdut Examples ======== >>> from sympy import KroneckerProduct, MatrixSymbol, symbols >>> m, n = symbols(r'm, n', integer=True) >>> A = MatrixSymbol('A', m, n) >>> B = MatrixSymbol('B', n, m) >>> KroneckerProduct(A, B).has_matching_shape(KroneckerProduct(B, A)) True >>> KroneckerProduct(A, B).has_matching_shape(KroneckerProduct(A, B)) False >>> KroneckerProduct(A, B).has_matching_shape(A) False ''' return (isinstance(other, KroneckerProduct) and self.cols == other.rows and len(self.args) == len(other.args) and all(a.cols == b.rows for (a, b) in zip(self.args, other.args))) def _eval_expand_kroneckerproduct(self, **hints): return flatten(canon(typed({KroneckerProduct: distribute(KroneckerProduct, MatAdd)}))(self)) def _kronecker_add(self, other): if self.structurally_equal(other): return self.__class__(*[a + b for (a, b) in zip(self.args, other.args)]) else: return self + other def _kronecker_mul(self, other): if self.has_matching_shape(other): return self.__class__(*[a*b for (a, b) in zip(self.args, other.args)]) else: return self * other def doit(self, **kwargs): deep = kwargs.get('deep', True) if deep: args = [arg.doit(**kwargs) for arg in self.args] else: args = self.args return canonicalize(KroneckerProduct(*args)) def validate(*args): if not all(arg.is_Matrix for arg in args): raise TypeError("Mix of Matrix and Scalar symbols") # rules def extract_commutative(kron): c_part = [] nc_part = [] for arg in kron.args: c, nc = arg.args_cnc() c_part.extend(c) nc_part.append(Mul._from_args(nc)) c_part = Mul(*c_part) if c_part != 1: return c_part*KroneckerProduct(*nc_part) return kron def matrix_kronecker_product(*matrices): """Compute the Kronecker product of a sequence of SymPy Matrices. This is the standard Kronecker product of matrices [1]. Parameters ========== matrices : tuple of MatrixBase instances The matrices to take the Kronecker product of. Returns ======= matrix : MatrixBase The Kronecker product matrix. Examples ======== >>> from sympy import Matrix >>> from sympy.matrices.expressions.kronecker import ( ... matrix_kronecker_product) >>> m1 = Matrix([[1,2],[3,4]]) >>> m2 = Matrix([[1,0],[0,1]]) >>> matrix_kronecker_product(m1, m2) Matrix([ [1, 0, 2, 0], [0, 1, 0, 2], [3, 0, 4, 0], [0, 3, 0, 4]]) >>> matrix_kronecker_product(m2, m1) Matrix([ [1, 2, 0, 0], [3, 4, 0, 0], [0, 0, 1, 2], [0, 0, 3, 4]]) References ========== [1] https://en.wikipedia.org/wiki/Kronecker_product """ # Make sure we have a sequence of Matrices if not all(isinstance(m, MatrixBase) for m in matrices): raise TypeError( 'Sequence of Matrices expected, got: %s' % repr(matrices) ) # Pull out the first element in the product. matrix_expansion = matrices[-1] # Do the kronecker product working from right to left. for mat in reversed(matrices[:-1]): rows = mat.rows cols = mat.cols # Go through each row appending kronecker product to. # running matrix_expansion. for i in range(rows): start = matrix_expansion*mat[i*cols] # Go through each column joining each item for j in range(cols - 1): start = start.row_join( matrix_expansion*mat[i*cols + j + 1] ) # If this is the first element, make it the start of the # new row. if i == 0: next = start else: next = next.col_join(start) matrix_expansion = next MatrixClass = max(matrices, key=lambda M: M._class_priority).__class__ if isinstance(matrix_expansion, MatrixClass): return matrix_expansion else: return MatrixClass(matrix_expansion) def explicit_kronecker_product(kron): # Make sure we have a sequence of Matrices if not all(isinstance(m, MatrixBase) for m in kron.args): return kron return matrix_kronecker_product(*kron.args) rules = (unpack, explicit_kronecker_product, flatten, extract_commutative) canonicalize = exhaust(condition(lambda x: isinstance(x, KroneckerProduct), do_one(*rules))) def _kronecker_dims_key(expr): if isinstance(expr, KroneckerProduct): return tuple(a.shape for a in expr.args) else: return (0,) def kronecker_mat_add(expr): from functools import reduce args = sift(expr.args, _kronecker_dims_key) nonkrons = args.pop((0,), None) if not args: return expr krons = [reduce(lambda x, y: x._kronecker_add(y), group) for group in args.values()] if not nonkrons: return MatAdd(*krons) else: return MatAdd(*krons) + nonkrons def kronecker_mat_mul(expr): # modified from block matrix code factor, matrices = expr.as_coeff_matrices() i = 0 while i < len(matrices) - 1: A, B = matrices[i:i+2] if isinstance(A, KroneckerProduct) and isinstance(B, KroneckerProduct): matrices[i] = A._kronecker_mul(B) matrices.pop(i+1) else: i += 1 return factor*MatMul(*matrices) def kronecker_mat_pow(expr): if isinstance(expr.base, KroneckerProduct): return KroneckerProduct(*[MatPow(a, expr.exp) for a in expr.base.args]) else: return expr def combine_kronecker(expr): """Combine KronekeckerProduct with expression. If possible write operations on KroneckerProducts of compatible shapes as a single KroneckerProduct. Examples ======== >>> from sympy.matrices.expressions import MatrixSymbol, KroneckerProduct, combine_kronecker >>> from sympy import symbols >>> m, n = symbols(r'm, n', integer=True) >>> A = MatrixSymbol('A', m, n) >>> B = MatrixSymbol('B', n, m) >>> combine_kronecker(KroneckerProduct(A, B)*KroneckerProduct(B, A)) KroneckerProduct(A*B, B*A) >>> combine_kronecker(KroneckerProduct(A, B)+KroneckerProduct(B.T, A.T)) KroneckerProduct(A + B.T, B + A.T) >>> combine_kronecker(KroneckerProduct(A, B)**m) KroneckerProduct(A**m, B**m) """ def haskron(expr): return isinstance(expr, MatrixExpr) and expr.has(KroneckerProduct) rule = exhaust( bottom_up(exhaust(condition(haskron, typed( {MatAdd: kronecker_mat_add, MatMul: kronecker_mat_mul, MatPow: kronecker_mat_pow}))))) result = rule(expr) try: return result.doit() except AttributeError: return result

efa89b95a9c4d25f54f6fd8d5b267de9f81268c98c98505f0c9971122e08d3c4

from __future__ import print_function, division from sympy import Basic, Expr, sympify, S from sympy.matrices.matrices import MatrixBase from .matexpr import ShapeError class Trace(Expr): """Matrix Trace Represents the trace of a matrix expression. Examples ======== >>> from sympy import MatrixSymbol, Trace, eye >>> A = MatrixSymbol('A', 3, 3) >>> Trace(A) Trace(A) """ is_Trace = True def __new__(cls, mat): mat = sympify(mat) if not mat.is_Matrix: raise TypeError("input to Trace, %s, is not a matrix" % str(mat)) if not mat.is_square: raise ShapeError("Trace of a non-square matrix") return Basic.__new__(cls, mat) def _eval_transpose(self): return self def _eval_derivative(self, v): from sympy.matrices.expressions.matexpr import _matrix_derivative return _matrix_derivative(self, v) def _eval_derivative_matrix_lines(self, x): r = self.args[0]._eval_derivative_matrix_lines(x) for lr in r: if lr.higher == 1: lr.higher *= lr.first * lr.second.T else: # This is not a matrix line: lr.higher *= Trace(lr.first * lr.second.T) lr.first = S.One lr.second = S.One return r @property def arg(self): return self.args[0] def doit(self, **kwargs): if kwargs.get('deep', True): arg = self.arg.doit(**kwargs) try: return arg._eval_trace() except (AttributeError, NotImplementedError): return Trace(arg) else: # _eval_trace would go too deep here if isinstance(self.arg, MatrixBase): return trace(self.arg) else: return Trace(self.arg) def _eval_rewrite_as_Sum(self, expr, **kwargs): from sympy import Sum, Dummy i = Dummy('i') return Sum(self.arg[i, i], (i, 0, self.arg.rows-1)).doit() def trace(expr): """Trace of a Matrix. Sum of the diagonal elements. Examples ======== >>> from sympy import trace, Symbol, MatrixSymbol, pprint, eye >>> n = Symbol('n') >>> X = MatrixSymbol('X', n, n) # A square matrix >>> trace(2*X) 2*Trace(X) >>> trace(eye(3)) 3 """ return Trace(expr).doit()

098bbd383a9df25eb65ffc9e8092d8af1cd6dee9fa32ba6a545b60113b8337c4

from __future__ import print_function, division from sympy.core.compatibility import reduce from operator import add from sympy.core import Add, Basic, sympify from sympy.functions import adjoint from sympy.matrices.matrices import MatrixBase from sympy.matrices.expressions.transpose import transpose from sympy.strategies import (rm_id, unpack, flatten, sort, condition, exhaust, do_one, glom) from sympy.matrices.expressions.matexpr import MatrixExpr, ShapeError, ZeroMatrix from sympy.utilities import default_sort_key, sift from sympy.core.operations import AssocOp class MatAdd(MatrixExpr, Add): """A Sum of Matrix Expressions MatAdd inherits from and operates like SymPy Add Examples ======== >>> from sympy import MatAdd, MatrixSymbol >>> A = MatrixSymbol('A', 5, 5) >>> B = MatrixSymbol('B', 5, 5) >>> C = MatrixSymbol('C', 5, 5) >>> MatAdd(A, B, C) A + B + C """ is_MatAdd = True def __new__(cls, *args, **kwargs): args = list(map(sympify, args)) check = kwargs.get('check', False) obj = Basic.__new__(cls, *args) if check: if all(not isinstance(i, MatrixExpr) for i in args): return Add.fromiter(args) validate(*args) return obj @property def shape(self): return self.args[0].shape def _entry(self, i, j, expand=None): return Add(*[arg._entry(i, j) for arg in self.args]) def _eval_transpose(self): return MatAdd(*[transpose(arg) for arg in self.args]).doit() def _eval_adjoint(self): return MatAdd(*[adjoint(arg) for arg in self.args]).doit() def _eval_trace(self): from .trace import trace return Add(*[trace(arg) for arg in self.args]).doit() def doit(self, **kwargs): deep = kwargs.get('deep', True) if deep: args = [arg.doit(**kwargs) for arg in self.args] else: args = self.args return canonicalize(MatAdd(*args)) def _eval_derivative_matrix_lines(self, x): add_lines = [arg._eval_derivative_matrix_lines(x) for arg in self.args] return [j for i in add_lines for j in i] def validate(*args): if not all(arg.is_Matrix for arg in args): raise TypeError("Mix of Matrix and Scalar symbols") A = args[0] for B in args[1:]: if A.shape != B.shape: raise ShapeError("Matrices %s and %s are not aligned"%(A, B)) factor_of = lambda arg: arg.as_coeff_mmul()[0] matrix_of = lambda arg: unpack(arg.as_coeff_mmul()[1]) def combine(cnt, mat): if cnt == 1: return mat else: return cnt * mat def merge_explicit(matadd): """ Merge explicit MatrixBase arguments Examples ======== >>> from sympy import MatrixSymbol, eye, Matrix, MatAdd, pprint >>> from sympy.matrices.expressions.matadd import merge_explicit >>> A = MatrixSymbol('A', 2, 2) >>> B = eye(2) >>> C = Matrix([[1, 2], [3, 4]]) >>> X = MatAdd(A, B, C) >>> pprint(X) [1 0] [1 2] A + [ ] + [ ] [0 1] [3 4] >>> pprint(merge_explicit(X)) [2 2] A + [ ] [3 5] """ groups = sift(matadd.args, lambda arg: isinstance(arg, MatrixBase)) if len(groups[True]) > 1: return MatAdd(*(groups[False] + [reduce(add, groups[True])])) else: return matadd rules = (rm_id(lambda x: x == 0 or isinstance(x, ZeroMatrix)), unpack, flatten, glom(matrix_of, factor_of, combine), merge_explicit, sort(default_sort_key)) canonicalize = exhaust(condition(lambda x: isinstance(x, MatAdd), do_one(*rules)))

3852db79b25e6dd9fd319d7fddebd688816c29a8c79885f1e8e0f55067e3bd18

""" Some examples have been taken from: http://www.math.uwaterloo.ca/~hwolkowi//matrixcookbook.pdf """ from sympy import MatrixSymbol, Inverse, symbols, Determinant, Trace, Derivative from sympy import MatAdd, Identity, MatMul, ZeroMatrix k = symbols("k") X = MatrixSymbol("X", k, k) x = MatrixSymbol("x", k, 1) A = MatrixSymbol("A", k, k) B = MatrixSymbol("B", k, k) C = MatrixSymbol("C", k, k) D = MatrixSymbol("D", k, k) a = MatrixSymbol("a", k, 1) b = MatrixSymbol("b", k, 1) c = MatrixSymbol("c", k, 1) d = MatrixSymbol("d", k, 1) def test_matrix_derivative_non_matrix_result(): # This is a 4-dimensional array: assert A.diff(A) == Derivative(A, A) assert A.T.diff(A) == Derivative(A.T, A) assert (2*A).diff(A) == Derivative(2*A, A) assert MatAdd(A, A).diff(A) == Derivative(MatAdd(A, A), A) assert (A + B).diff(A) == Derivative(A + B, A) # TODO: `B` can be removed. def test_matrix_derivative_trivial_cases(): # Cookbook example 33: assert X.diff(A) == 0 def test_matrix_derivative_with_inverse(): # Cookbook example 61: expr = a.T*Inverse(X)*b assert expr.diff(X) == -Inverse(X).T*a*b.T*Inverse(X).T # Cookbook example 62: expr = Determinant(Inverse(X)) # Not implemented yet: # assert expr.diff(X) == -Determinant(X.inv())*(X.inv()).T # Cookbook example 63: expr = Trace(A*Inverse(X)*B) assert expr.diff(X) == -(X**(-1)*B*A*X**(-1)).T # Cookbook example 64: expr = Trace(Inverse(X + A)) assert expr.diff(X) == -(Inverse(X + A)).T**2 def test_matrix_derivative_vectors_and_scalars(): # Cookbook example 69: expr = x.T*a assert expr.diff(x) == a expr = a.T*x assert expr.diff(x) == a # Cookbook example 70: expr = a.T*X*b assert expr.diff(X) == a*b.T # Cookbook example 71: expr = a.T*X.T*b assert expr.diff(X) == b*a.T # Cookbook example 72: expr = a.T*X*a assert expr.diff(X) == a*a.T expr = a.T*X.T*a assert expr.diff(X) == a*a.T # Cookbook example 77: expr = b.T*X.T*X*c assert expr.diff(X) == X*b*c.T + X*c*b.T # Cookbook example 78: expr = (B*x + b).T*C*(D*x + d) assert expr.diff(x) == B.T*C*(D*x + d) + D.T*C.T*(B*x + b) # Cookbook example 81: expr = x.T*B*x assert expr.diff(x) == B*x + B.T*x # Cookbook example 82: expr = b.T*X.T*D*X*c assert expr.diff(X) == D.T*X*b*c.T + D*X*c*b.T # Cookbook example 83: expr = (X*b + c).T*D*(X*b + c) assert expr.diff(X) == D*(X*b + c)*b.T + D.T*(X*b + c)*b.T def test_matrix_derivatives_of_traces(): ## First order: # Cookbook example 99: expr = Trace(X) assert expr.diff(X) == Identity(k) # Cookbook example 100: expr = Trace(X*A) assert expr.diff(X) == A.T # Cookbook example 101: expr = Trace(A*X*B) assert expr.diff(X) == A.T*B.T # Cookbook example 102: expr = Trace(A*X.T*B) assert expr.diff(X) == B*A # Cookbook example 103: expr = Trace(X.T*A) assert expr.diff(X) == A # Cookbook example 104: expr = Trace(A*X.T) assert expr.diff(X) == A # Cookbook example 105: # TODO: TensorProduct is not supported #expr = Trace(TensorProduct(A, X)) #assert expr.diff(X) == Trace(A)*Identity(k) ## Second order: # Cookbook example 106: expr = Trace(X**2) assert expr.diff(X) == 2*X.T # Cookbook example 107: expr = Trace(X**2*B) # TODO: wrong result #assert expr.diff(X) == (X*B + B*X).T expr = Trace(MatMul(X, X, B)) assert expr.diff(X) == (X*B + B*X).T # Cookbook example 108: expr = Trace(X.T*B*X) assert expr.diff(X) == B*X + B.T*X # Cookbook example 109: expr = Trace(B*X*X.T) assert expr.diff(X) == B*X + B.T*X # Cookbook example 110: expr = Trace(X*X.T*B) assert expr.diff(X) == B*X + B.T*X # Cookbook example 111: expr = Trace(X*B*X.T) assert expr.diff(X) == X*B.T + X*B # Cookbook example 112: expr = Trace(B*X.T*X) assert expr.diff(X) == X*B.T + X*B # Cookbook example 113: expr = Trace(X.T*X*B) assert expr.diff(X) == X*B.T + X*B # Cookbook example 114: expr = Trace(A*X*B*X) assert expr.diff(X) == A.T*X.T*B.T + B.T*X.T*A.T # Cookbook example 115: expr = Trace(X.T*X) assert expr.diff(X) == 2*X expr = Trace(X*X.T) assert expr.diff(X) == 2*X # Cookbook example 116: expr = Trace(B.T*X.T*C*X*B) assert expr.diff(X) == C.T*X*B*B.T + C*X*B*B.T # Cookbook example 117: expr = Trace(X.T*B*X*C) assert expr.diff(X) == B*X*C + B.T*X*C.T # Cookbook example 118: expr = Trace(A*X*B*X.T*C) assert expr.diff(X) == A.T*C.T*X*B.T + C*A*X*B # Cookbook example 119: expr = Trace((A*X*B + C)*(A*X*B + C).T) assert expr.diff(X) == 2*A.T*(A*X*B + C)*B.T # Cookbook example 120: # TODO: no support for TensorProduct. # expr = Trace(TensorProduct(X, X)) # expr = Trace(X)*Trace(X) # expr.diff(X) == 2*Trace(X)*Identity(k) # Higher Order # Cookbook example 121: expr = Trace(X**k) #assert expr.diff(X) == k*(X**(k-1)).T # Cookbook example 122: expr = Trace(A*X**k) #assert expr.diff(X) == # Needs indices # Cookbook example 123: expr = Trace(B.T*X.T*C*X*X.T*C*X*B) assert expr.diff(X) == C*X*X.T*C*X*B*B.T + C.T*X*B*B.T*X.T*C.T*X + C*X*B*B.T*X.T*C*X + C.T*X*X.T*C.T*X*B*B.T # Other # Cookbook example 124: expr = Trace(A*X**(-1)*B) assert expr.diff(X) == -Inverse(X).T*A.T*B.T*Inverse(X).T # Cookbook example 125: expr = Trace(Inverse(X.T*C*X)*A) # Warning: result in the cookbook is equivalent if B and C are symmetric: assert expr.diff(X) == - X.inv().T*A.T*X.inv()*C.inv().T*X.inv().T - X.inv().T*A*X.inv()*C.inv()*X.inv().T # Cookbook example 126: expr = Trace((X.T*C*X).inv()*(X.T*B*X)) assert expr.diff(X) == -2*C*X*(X.T*C*X).inv()*X.T*B*X*(X.T*C*X).inv() + 2*B*X*(X.T*C*X).inv() # Cookbook example 127: expr = Trace((A + X.T*C*X).inv()*(X.T*B*X)) # Warning: result in the cookbook is equivalent if B and C are symmetric: assert expr.diff(X) == B*X*Inverse(A + X.T*C*X) - C*X*Inverse(A + X.T*C*X)*X.T*B*X*Inverse(A + X.T*C*X) - C.T*X*Inverse(A.T + (C*X).T*X)*X.T*B.T*X*Inverse(A.T + (C*X).T*X) + B.T*X*Inverse(A.T + (C*X).T*X) def test_derivatives_of_complicated_matrix_expr(): expr = a.T*(A*X*(X.T*B + X*A) + B.T*X.T*(a*b.T*(X*D*X.T + X*(X.T*B + A*X)*D*B - X.T*C.T*A)*B + B*(X*D.T + B*A*X*A.T - 3*X*D))*B + 42*X*B*X.T*A.T*(X + X.T))*b result = (B*(B*A*X*A.T - 3*X*D + X*D.T) + a*b.T*(X*(A*X + X.T*B)*D*B + X*D*X.T - X.T*C.T*A)*B)*B*b*a.T*B.T + B**2*b*a.T*B.T*X.T*a*b.T*X*D + 42*A*X*B.T*X.T*a*b.T + B*D*B**3*b*a.T*B.T*X.T*a*b.T*X + B*b*a.T*A*X + 42*a*b.T*(X + X.T)*A*X*B.T + b*a.T*X*B*a*b.T*B.T**2*X*D.T + b*a.T*X*B*a*b.T*B.T**3*D.T*(B.T*X + X.T*A.T) + 42*b*a.T*X*B*X.T*A.T + 42*A.T*(X + X.T)*b*a.T*X*B + A.T*B.T**2*X*B*a*b.T*B.T*A + A.T*a*b.T*(A.T*X.T + B.T*X) + A.T*X.T*b*a.T*X*B*a*b.T*B.T**3*D.T + B.T*X*B*a*b.T*B.T*D - 3*B.T*X*B*a*b.T*B.T*D.T - C.T*A*B**2*b*a.T*B.T*X.T*a*b.T + X.T*A.T*a*b.T*A.T assert expr.diff(X) == result def test_mixed_deriv_mixed_expressions(): expr = Trace(A)*A # TODO: this is not yet supported: assert expr.diff(A) == Derivative(expr, A) expr = Trace(Trace(A)*A) assert expr.diff(A) == (2*Trace(A))*Identity(k)

50b66f6d006fd4c65900552a00eff9cf2721ba8533ddb82dc0bcb6d6ca7b7254

from sympy.matrices.expressions.applyfunc import ElementwiseApplyFunction from sympy import (Matrix, Lambda, MatrixBase, MatrixSymbol, exp, symbols, MatMul, sin) from sympy.utilities.pytest import raises from sympy.matrices.common import ShapeError X = MatrixSymbol("X", 3, 3) Y = MatrixSymbol("Y", 3, 3) k = symbols("k") Xk = MatrixSymbol("X", k, k) Xd = X.as_explicit() x, y, z, t = symbols("x y z t") def test_applyfunc_matrix(): double = Lambda(x, x**2) expr = ElementwiseApplyFunction(double, Xd) assert isinstance(expr, ElementwiseApplyFunction) assert expr.doit() == Xd.applyfunc(lambda x: x**2) assert expr.shape == (3, 3) expr = ElementwiseApplyFunction(double, X) assert isinstance(expr, ElementwiseApplyFunction) assert isinstance(expr.doit(), ElementwiseApplyFunction) assert expr == X.applyfunc(double) expr = ElementwiseApplyFunction(exp, X*Y) assert expr.expr == X*Y assert expr.function == exp assert expr == (X*Y).applyfunc(exp) assert isinstance(X*expr, MatMul) assert (X*expr).shape == (3, 3) Z = MatrixSymbol("Z", 2, 3) assert (Z*expr).shape == (2, 3) expr = ElementwiseApplyFunction(exp, Z.T)*ElementwiseApplyFunction(exp, Z) assert expr.shape == (3, 3) expr = ElementwiseApplyFunction(exp, Z)*ElementwiseApplyFunction(exp, Z.T) assert expr.shape == (2, 2) raises(ShapeError, lambda: ElementwiseApplyFunction(exp, Z)*ElementwiseApplyFunction(exp, Z)) M = Matrix([[x, y], [z, t]]) expr = ElementwiseApplyFunction(sin, M) assert isinstance(expr, ElementwiseApplyFunction) assert expr.function == sin assert expr.expr == M assert expr.doit() == M.applyfunc(sin) assert expr.doit() == Matrix([[sin(x), sin(y)], [sin(z), sin(t)]]) expr = ElementwiseApplyFunction(double, Xk) assert expr.doit() == expr assert expr.subs(k, 2).shape == (2, 2) assert (expr*expr).shape == (k, k) M = MatrixSymbol("M", k, t) expr2 = M.T*expr*M assert isinstance(expr2, MatMul) assert expr2.args[1] == expr assert expr2.shape == (t, t) expr3 = expr*M assert expr3.shape == (k, t) raises(ShapeError, lambda: M*expr)

bb4385740fc6aa84b072e9c83a98ac60fee7adf464f3e108baab1a41dfbc385a

import warnings from sympy import (plot_implicit, cos, Symbol, symbols, Eq, sin, re, And, Or, exp, I, tan, pi) from sympy.plotting.plot import unset_show from tempfile import NamedTemporaryFile, mkdtemp from sympy.utilities.pytest import skip, warns from sympy.external import import_module from sympy.utilities.tmpfiles import TmpFileManager, cleanup_tmp_files #Set plots not to show unset_show() def tmp_file(dir=None, name=''): return NamedTemporaryFile( suffix='.png', dir=dir, delete=False).name def plot_and_save(expr, *args, **kwargs): name = kwargs.pop('name', '') dir = kwargs.pop('dir', None) p = plot_implicit(expr, *args, **kwargs) p.save(tmp_file(dir=dir, name=name)) # Close the plot to avoid a warning from matplotlib p._backend.close() def plot_implicit_tests(name): temp_dir = mkdtemp() TmpFileManager.tmp_folder(temp_dir) x = Symbol('x') y = Symbol('y') z = Symbol('z') #implicit plot tests plot_and_save(Eq(y, cos(x)), (x, -5, 5), (y, -2, 2), name=name, dir=temp_dir) plot_and_save(Eq(y**2, x**3 - x), (x, -5, 5), (y, -4, 4), name=name, dir=temp_dir) plot_and_save(y > 1 / x, (x, -5, 5), (y, -2, 2), name=name, dir=temp_dir) plot_and_save(y < 1 / tan(x), (x, -5, 5), (y, -2, 2), name=name, dir=temp_dir) plot_and_save(y >= 2 * sin(x) * cos(x), (x, -5, 5), (y, -2, 2), name=name, dir=temp_dir) plot_and_save(y <= x**2, (x, -3, 3), (y, -1, 5), name=name, dir=temp_dir) #Test all input args for plot_implicit plot_and_save(Eq(y**2, x**3 - x), dir=temp_dir) plot_and_save(Eq(y**2, x**3 - x), adaptive=False, dir=temp_dir) plot_and_save(Eq(y**2, x**3 - x), adaptive=False, points=500, dir=temp_dir) plot_and_save(y > x, (x, -5, 5), dir=temp_dir) plot_and_save(And(y > exp(x), y > x + 2), dir=temp_dir) plot_and_save(Or(y > x, y > -x), dir=temp_dir) plot_and_save(x**2 - 1, (x, -5, 5), dir=temp_dir) plot_and_save(x**2 - 1, dir=temp_dir) plot_and_save(y > x, depth=-5, dir=temp_dir) plot_and_save(y > x, depth=5, dir=temp_dir) plot_and_save(y > cos(x), adaptive=False, dir=temp_dir) plot_and_save(y < cos(x), adaptive=False, dir=temp_dir) plot_and_save(And(y > cos(x), Or(y > x, Eq(y, x))), dir=temp_dir) plot_and_save(y - cos(pi / x), dir=temp_dir) #Test plots which cannot be rendered using the adaptive algorithm with warns(UserWarning, match="Adaptive meshing could not be applied"): plot_and_save(Eq(y, re(cos(x) + I*sin(x))), name=name, dir=temp_dir) plot_and_save(x**2 - 1, title='An implicit plot', dir=temp_dir) def test_line_color(): x, y = symbols('x, y') p = plot_implicit(x**2 + y**2 - 1, line_color="green", show=False) assert p._series[0].line_color == "green" p = plot_implicit(x**2 + y**2 - 1, line_color='r', show=False) assert p._series[0].line_color == "r" def test_matplotlib(): matplotlib = import_module('matplotlib', min_module_version='1.1.0', catch=(RuntimeError,)) if matplotlib: try: plot_implicit_tests('test') test_line_color() finally: TmpFileManager.cleanup() else: skip("Matplotlib not the default backend")

1400a85b3488caad14a7dcf635e6a2e18e9ce139518b74e07007ce4f508b76a7

""" SymPy is a Python library for symbolic mathematics. It aims to become a full-featured computer algebra system (CAS) while keeping the code as simple as possible in order to be comprehensible and easily extensible. SymPy is written entirely in Python. It depends on mpmath, and other external libraries may be optionally for things like plotting support. See the webpage for more information and documentation: https://sympy.org """ from __future__ import absolute_import, print_function del absolute_import, print_function try: import mpmath except ImportError: raise ImportError("SymPy now depends on mpmath as an external library. " "See https://docs.sympy.org/latest/install.html#mpmath for more information.") del mpmath from sympy.release import __version__ if 'dev' in __version__: def enable_warnings(): import warnings warnings.filterwarnings('default', '.*', DeprecationWarning, module='sympy.*') del warnings enable_warnings() del enable_warnings import sys if ((sys.version_info[0] == 2 and sys.version_info[1] < 7) or (sys.version_info[0] == 3 and sys.version_info[1] < 4)): raise ImportError("Python version 2.7 or 3.4 or above " "is required for SymPy.") del sys def __sympy_debug(): # helper function so we don't import os globally import os debug_str = os.getenv('SYMPY_DEBUG', 'False') if debug_str in ('True', 'False'): return eval(debug_str) else: raise RuntimeError("unrecognized value for SYMPY_DEBUG: %s" % debug_str) SYMPY_DEBUG = __sympy_debug() from .core import * from .logic import * from .assumptions import * from .polys import * from .series import * from .functions import * from .ntheory import * from .concrete import * from .discrete import * from .simplify import * from .sets import * from .solvers import * from .matrices import * from .geometry import * from .utilities import * from .integrals import * from .tensor import * from .parsing import * from .calculus import * from .algebras import * # This module causes conflicts with other modules: # from .stats import * # Adds about .04-.05 seconds of import time # from combinatorics import * # This module is slow to import: #from physics import units from .plotting import plot, textplot, plot_backends, plot_implicit from .printing import * from .interactive import init_session, init_printing evalf._create_evalf_table() # This is slow to import: #import abc from .deprecated import *

bc17eb214da188a1feaabd712d8b6fb525b64aad33fa4483ecbe8a3f3a419372

""" Extract reference documentation from the NumPy source tree. """ from __future__ import division, absolute_import, print_function import inspect import textwrap import re import pydoc try: from collections.abc import Mapping except ImportError: # Python 2 from collections import Mapping import sys class Reader(object): """ A line-based string reader. """ def __init__(self, data): """ Parameters ---------- data : str String with lines separated by '\n'. """ if isinstance(data, list): self._str = data else: self._str = data.split('\n') # store string as list of lines self.reset() def __getitem__(self, n): return self._str[n] def reset(self): self._l = 0 # current line nr def read(self): if not self.eof(): out = self[self._l] self._l += 1 return out else: return '' def seek_next_non_empty_line(self): for l in self[self._l:]: if l.strip(): break else: self._l += 1 def eof(self): return self._l >= len(self._str) def read_to_condition(self, condition_func): start = self._l for line in self[start:]: if condition_func(line): return self[start:self._l] self._l += 1 if self.eof(): return self[start:self._l + 1] return [] def read_to_next_empty_line(self): self.seek_next_non_empty_line() def is_empty(line): return not line.strip() return self.read_to_condition(is_empty) def read_to_next_unindented_line(self): def is_unindented(line): return (line.strip() and (len(line.lstrip()) == len(line))) return self.read_to_condition(is_unindented) def peek(self, n=0): if self._l + n < len(self._str): return self[self._l + n] else: return '' def is_empty(self): return not ''.join(self._str).strip() class NumpyDocString(Mapping): def __init__(self, docstring, config={}): docstring = textwrap.dedent(docstring).split('\n') self._doc = Reader(docstring) self._parsed_data = { 'Signature': '', 'Summary': [''], 'Extended Summary': [], 'Parameters': [], 'Returns': [], 'Yields': [], 'Raises': [], 'Warns': [], 'Other Parameters': [], 'Attributes': [], 'Methods': [], 'See Also': [], # 'Notes': [], 'Warnings': [], 'References': '', # 'Examples': '', 'index': {} } self._other_keys = [] self._parse() def __getitem__(self, key): return self._parsed_data[key] def __setitem__(self, key, val): if key not in self._parsed_data: self._other_keys.append(key) self._parsed_data[key] = val def __iter__(self): return iter(self._parsed_data) def __len__(self): return len(self._parsed_data) def _is_at_section(self): self._doc.seek_next_non_empty_line() if self._doc.eof(): return False l1 = self._doc.peek().strip() # e.g. Parameters if l1.startswith('.. index::'): return True l2 = self._doc.peek(1).strip() # ---------- or ========== return l2.startswith('-'*len(l1)) or l2.startswith('='*len(l1)) def _strip(self, doc): i = 0 j = 0 for i, line in enumerate(doc): if line.strip(): break for j, line in enumerate(doc[::-1]): if line.strip(): break return doc[i:len(doc) - j] def _read_to_next_section(self): section = self._doc.read_to_next_empty_line() while not self._is_at_section() and not self._doc.eof(): if not self._doc.peek(-1).strip(): # previous line was empty section += [''] section += self._doc.read_to_next_empty_line() return section def _read_sections(self): while not self._doc.eof(): data = self._read_to_next_section() name = data[0].strip() if name.startswith('..'): # index section yield name, data[1:] elif len(data) < 2: yield StopIteration else: yield name, self._strip(data[2:]) def _parse_param_list(self, content): r = Reader(content) params = [] while not r.eof(): header = r.read().strip() if ' : ' in header: arg_name, arg_type = header.split(' : ')[:2] else: arg_name, arg_type = header, '' desc = r.read_to_next_unindented_line() desc = dedent_lines(desc) params.append((arg_name, arg_type, desc)) return params _name_rgx = re.compile(r"^\s*(:(?P<role>\w+):`(?P<name>[a-zA-Z0-9_.-]+)`|" r" (?P<name2>[a-zA-Z0-9_.-]+))\s*", re.X) def _parse_see_also(self, content): """ func_name : Descriptive text continued text another_func_name : Descriptive text func_name1, func_name2, :meth:`func_name`, func_name3 """ items = [] def parse_item_name(text): """Match ':role:`name`' or 'name'""" m = self._name_rgx.match(text) if m: g = m.groups() if g[1] is None: return g[3], None else: return g[2], g[1] raise ValueError("%s is not an item name" % text) def push_item(name, rest): if not name: return name, role = parse_item_name(name) items.append((name, list(rest), role)) del rest[:] current_func = None rest = [] for line in content: if not line.strip(): continue m = self._name_rgx.match(line) if m and line[m.end():].strip().startswith(':'): push_item(current_func, rest) current_func, line = line[:m.end()], line[m.end():] rest = [line.split(':', 1)[1].strip()] if not rest[0]: rest = [] elif not line.startswith(' '): push_item(current_func, rest) current_func = None if ',' in line: for func in line.split(','): if func.strip(): push_item(func, []) elif line.strip(): current_func = line elif current_func is not None: rest.append(line.strip()) push_item(current_func, rest) return items def _parse_index(self, section, content): """ .. index: default :refguide: something, else, and more """ def strip_each_in(lst): return [s.strip() for s in lst] out = {} section = section.split('::') if len(section) > 1: out['default'] = strip_each_in(section[1].split(','))[0] for line in content: line = line.split(':') if len(line) > 2: out[line[1]] = strip_each_in(line[2].split(',')) return out def _parse_summary(self): """Grab signature (if given) and summary""" if self._is_at_section(): return # If several signatures present, take the last one while True: summary = self._doc.read_to_next_empty_line() summary_str = " ".join([s.strip() for s in summary]).strip() if re.compile('^([\w., ]+=)?\s*[\w\.]+$.*$$').match(summary_str): self['Signature'] = summary_str if not self._is_at_section(): continue break if summary is not None: self['Summary'] = summary if not self._is_at_section(): self['Extended Summary'] = self._read_to_next_section() def _parse(self): self._doc.reset() self._parse_summary() sections = list(self._read_sections()) section_names = set([section for section, content in sections]) has_returns = 'Returns' in section_names has_yields = 'Yields' in section_names # We could do more tests, but we are not. Arbitrarily. if has_returns and has_yields: msg = 'Docstring contains both a Returns and Yields section.' raise ValueError(msg) for (section, content) in sections: if not section.startswith('..'): section = (s.capitalize() for s in section.split(' ')) section = ' '.join(section) if section in ('Parameters', 'Returns', 'Yields', 'Raises', 'Warns', 'Other Parameters', 'Attributes', 'Methods'): self[section] = self._parse_param_list(content) elif section.startswith('.. index::'): self['index'] = self._parse_index(section, content) elif section == 'See Also': self['See Also'] = self._parse_see_also(content) else: self[section] = content # string conversion routines def _str_header(self, name, symbol='-'): return [name, len(name)*symbol] def _str_indent(self, doc, indent=4): out = [] for line in doc: out += [' '*indent + line] return out def _str_signature(self): if self['Signature']: return [self['Signature'].replace('*', '\*')] + [''] else: return [''] def _str_summary(self): if self['Summary']: return self['Summary'] + [''] else: return [] def _str_extended_summary(self): if self['Extended Summary']: return self['Extended Summary'] + [''] else: return [] def _str_param_list(self, name): out = [] if self[name]: out += self._str_header(name) for param, param_type, desc in self[name]: if param_type: out += ['%s : %s' % (param, param_type)] else: out += [param] out += self._str_indent(desc) out += [''] return out def _str_section(self, name): out = [] if self[name]: out += self._str_header(name) out += self[name] out += [''] return out def _str_see_also(self, func_role): if not self['See Also']: return [] out = [] out += self._str_header("See Also") last_had_desc = True for func, desc, role in self['See Also']: if role: link = ':%s:`%s`' % (role, func) elif func_role: link = ':%s:`%s`' % (func_role, func) else: link = "`%s`_" % func if desc or last_had_desc: out += [''] out += [link] else: out[-1] += ", %s" % link if desc: out += self._str_indent([' '.join(desc)]) last_had_desc = True else: last_had_desc = False out += [''] return out def _str_index(self): idx = self['index'] out = [] out += ['.. index:: %s' % idx.get('default', '')] for section, references in idx.items(): if section == 'default': continue out += [' :%s: %s' % (section, ', '.join(references))] return out def __str__(self, func_role=''): out = [] out += self._str_signature() out += self._str_summary() out += self._str_extended_summary() for param_list in ('Parameters', 'Returns', 'Yields', 'Other Parameters', 'Raises', 'Warns'): out += self._str_param_list(param_list) out += self._str_section('Warnings') out += self._str_see_also(func_role) for s in ('Notes', 'References', 'Examples'): out += self._str_section(s) for param_list in ('Attributes', 'Methods'): out += self._str_param_list(param_list) out += self._str_index() return '\n'.join(out) def indent(str, indent=4): indent_str = ' '*indent if str is None: return indent_str lines = str.split('\n') return '\n'.join(indent_str + l for l in lines) def dedent_lines(lines): """Deindent a list of lines maximally""" return textwrap.dedent("\n".join(lines)).split("\n") def header(text, style='-'): return text + '\n' + style*len(text) + '\n' class FunctionDoc(NumpyDocString): def __init__(self, func, role='func', doc=None, config={}): self._f = func self._role = role # e.g. "func" or "meth" if doc is None: if func is None: raise ValueError("No function or docstring given") doc = inspect.getdoc(func) or '' NumpyDocString.__init__(self, doc) if not self['Signature'] and func is not None: func, func_name = self.get_func() try: # try to read signature if sys.version_info[0] >= 3: argspec = inspect.getfullargspec(func) else: argspec = inspect.getargspec(func) argspec = inspect.formatargspec(*argspec) argspec = argspec.replace('*', '\*') signature = '%s%s' % (func_name, argspec) except TypeError as e: signature = '%s()' % func_name self['Signature'] = signature def get_func(self): func_name = getattr(self._f, '__name__', self.__class__.__name__) if inspect.isclass(self._f): func = getattr(self._f, '__call__', self._f.__init__) else: func = self._f return func, func_name def __str__(self): out = '' func, func_name = self.get_func() signature = self['Signature'].replace('*', '\*') roles = {'func': 'function', 'meth': 'method'} if self._role: if self._role not in roles: print("Warning: invalid role %s" % self._role) out += '.. %s:: %s\n \n\n' % (roles.get(self._role, ''), func_name) out += super(FunctionDoc, self).__str__(func_role=self._role) return out class ClassDoc(NumpyDocString): extra_public_methods = ['__call__'] def __init__(self, cls, doc=None, modulename='', func_doc=FunctionDoc, config={}): if not inspect.isclass(cls) and cls is not None: raise ValueError("Expected a class or None, but got %r" % cls) self._cls = cls self.show_inherited_members = config.get( 'show_inherited_class_members', True) if modulename and not modulename.endswith('.'): modulename += '.' self._mod = modulename if doc is None: if cls is None: raise ValueError("No class or documentation string given") doc = pydoc.getdoc(cls) NumpyDocString.__init__(self, doc) if config.get('show_class_members', True): def splitlines_x(s): if not s: return [] else: return s.splitlines() for field, items in [('Methods', self.methods), ('Attributes', self.properties)]: if not self[field]: doc_list = [] for name in sorted(items): try: doc_item = pydoc.getdoc(getattr(self._cls, name)) doc_list.append((name, '', splitlines_x(doc_item))) except AttributeError: pass # method doesn't exist self[field] = doc_list @property def methods(self): if self._cls is None: return [] return [name for name, func in inspect_getmembers(self._cls) if ((not name.startswith('_') or name in self.extra_public_methods) and callable(func))] @property def properties(self): if self._cls is None: return [] return [name for name, func in inspect_getmembers(self._cls) if not name.startswith('_') and func is None] # This function was taken verbatim from Python 2.7 inspect.getmembers() from # the standard library. The difference from Python < 2.7 is that there is the # try/except AttributeError clause added, which catches exceptions like this # one: https://gist.github.com/1471949 def inspect_getmembers(object, predicate=None): """ Return all members of an object as (name, value) pairs sorted by name. Optionally, only return members that satisfy a given predicate. """ results = [] for key in dir(object): try: value = getattr(object, key) except AttributeError: continue if not predicate or predicate(value): results.append((key, value)) results.sort() return results def _is_show_member(self, name): if self.show_inherited_members: return True # show all class members if name not in self._cls.__dict__: return False # class member is inherited, we do not show it return True

33b1547d5da85e85a3f8d7f33e136aaa459764ee64967b8ef7865627ef213cb6

from __future__ import division, absolute_import, print_function import sys import re import inspect import textwrap import pydoc import sphinx import collections from docscrape import NumpyDocString, FunctionDoc, ClassDoc if sys.version_info[0] >= 3: sixu = lambda s: s else: sixu = lambda s: unicode(s, 'unicode_escape') class SphinxDocString(NumpyDocString): def __init__(self, docstring, config={}): NumpyDocString.__init__(self, docstring, config=config) self.load_config(config) def load_config(self, config): self.use_plots = config.get('use_plots', False) self.class_members_toctree = config.get('class_members_toctree', True) # string conversion routines def _str_header(self, name, symbol='`'): return ['.. rubric:: ' + name, ''] def _str_field_list(self, name): return [':' + name + ':'] def _str_indent(self, doc, indent=4): out = [] for line in doc: out += [' '*indent + line] return out def _str_signature(self): return [''] if self['Signature']: return ['``%s``' % self['Signature']] + [''] else: return [''] def _str_summary(self): return self['Summary'] + [''] def _str_extended_summary(self): return self['Extended Summary'] + [''] def _str_returns(self, name='Returns'): out = [] if self[name]: out += self._str_field_list(name) out += [''] for param, param_type, desc in self[name]: if param_type: out += self._str_indent(['**%s** : %s' % (param.strip(), param_type)]) else: out += self._str_indent([param.strip()]) if desc: out += [''] out += self._str_indent(desc, 8) out += [''] return out def _str_param_list(self, name): out = [] if self[name]: out += self._str_field_list(name) out += [''] for param, param_type, desc in self[name]: if param_type: out += self._str_indent(['**%s** : %s' % (param.strip(), param_type)]) else: out += self._str_indent(['**%s**' % param.strip()]) if desc: out += [''] out += self._str_indent(desc, 8) out += [''] return out @property def _obj(self): if hasattr(self, '_cls'): return self._cls elif hasattr(self, '_f'): return self._f return None def _str_member_list(self, name): """ Generate a member listing, autosummary:: table where possible, and a table where not. """ out = [] if self[name]: out += ['.. rubric:: %s' % name, ''] prefix = getattr(self, '_name', '') if prefix: prefix = '~%s.' % prefix # Lines that are commented out are used to make the # autosummary:: table. Since SymPy does not use the # autosummary:: functionality, it is easiest to just comment it # out. # autosum = [] others = [] for param, param_type, desc in self[name]: param = param.strip() # Check if the referenced member can have a docstring or not param_obj = getattr(self._obj, param, None) if not (callable(param_obj) or isinstance(param_obj, property) or inspect.isgetsetdescriptor(param_obj)): param_obj = None # if param_obj and (pydoc.getdoc(param_obj) or not desc): # # Referenced object has a docstring # autosum += [" %s%s" % (prefix, param)] # else: others.append((param, param_type, desc)) # if autosum: # out += ['.. autosummary::'] # if self.class_members_toctree: # out += [' :toctree:'] # out += [''] + autosum if others: maxlen_0 = max(3, max([len(x[0]) for x in others])) hdr = sixu("=")*maxlen_0 + sixu(" ") + sixu("=")*10 fmt = sixu('%%%ds %%s ') % (maxlen_0,) out += ['', '', hdr] for param, param_type, desc in others: desc = sixu(" ").join(x.strip() for x in desc).strip() if param_type: desc = "(%s) %s" % (param_type, desc) out += [fmt % (param.strip(), desc)] out += [hdr] out += [''] return out def _str_section(self, name): out = [] if self[name]: out += self._str_header(name) out += [''] content = textwrap.dedent("\n".join(self[name])).split("\n") out += content out += [''] return out def _str_see_also(self, func_role): out = [] if self['See Also']: see_also = super(SphinxDocString, self)._str_see_also(func_role) out = ['.. seealso::', ''] out += self._str_indent(see_also[2:]) return out def _str_warnings(self): out = [] if self['Warnings']: out = ['.. warning::', ''] out += self._str_indent(self['Warnings']) return out def _str_index(self): idx = self['index'] out = [] if len(idx) == 0: return out out += ['.. index:: %s' % idx.get('default', '')] for section, references in idx.items(): if section == 'default': continue elif section == 'refguide': out += [' single: %s' % (', '.join(references))] else: out += [' %s: %s' % (section, ','.join(references))] return out def _str_references(self): out = [] if self['References']: out += self._str_header('References') if isinstance(self['References'], str): self['References'] = [self['References']] out.extend(self['References']) out += [''] # Latex collects all references to a separate bibliography, # so we need to insert links to it if sphinx.__version__ >= "0.6": out += ['.. only:: latex', ''] else: out += ['.. latexonly::', ''] items = [] for line in self['References']: m = re.match(r'.. \[([a-z0-9._-]+)\]', line, re.I) if m: items.append(m.group(1)) out += [' ' + ", ".join(["[%s]_" % item for item in items]), ''] return out def _str_examples(self): examples_str = "\n".join(self['Examples']) if (self.use_plots and 'import matplotlib' in examples_str and 'plot::' not in examples_str): out = [] out += self._str_header('Examples') out += ['.. plot::', ''] out += self._str_indent(self['Examples']) out += [''] return out else: return self._str_section('Examples') def __str__(self, indent=0, func_role="obj"): out = [] out += self._str_signature() out += self._str_index() + [''] out += self._str_summary() out += self._str_extended_summary() out += self._str_param_list('Parameters') out += self._str_returns('Returns') out += self._str_returns('Yields') for param_list in ('Other Parameters', 'Raises', 'Warns'): out += self._str_param_list(param_list) out += self._str_warnings() for s in self._other_keys: out += self._str_section(s) out += self._str_see_also(func_role) out += self._str_references() out += self._str_member_list('Attributes') out = self._str_indent(out, indent) return '\n'.join(out) class SphinxFunctionDoc(SphinxDocString, FunctionDoc): def __init__(self, obj, doc=None, config={}): self.load_config(config) FunctionDoc.__init__(self, obj, doc=doc, config=config) class SphinxClassDoc(SphinxDocString, ClassDoc): def __init__(self, obj, doc=None, func_doc=None, config={}): self.load_config(config) ClassDoc.__init__(self, obj, doc=doc, func_doc=None, config=config) class SphinxObjDoc(SphinxDocString): def __init__(self, obj, doc=None, config={}): self._f = obj self.load_config(config) SphinxDocString.__init__(self, doc, config=config) def get_doc_object(obj, what=None, doc=None, config={}): if inspect.isclass(obj): what = 'class' elif inspect.ismodule(obj): what = 'module' elif callable(obj): what = 'function' else: what = 'object' if what == 'class': return SphinxClassDoc(obj, func_doc=SphinxFunctionDoc, doc=doc, config=config) elif what in ('function', 'method'): return SphinxFunctionDoc(obj, doc=doc, config=config) else: if doc is None: doc = pydoc.getdoc(obj) return SphinxObjDoc(obj, doc, config=config)

3af3e32a847c46a7d6a71376c9059a3dedf7522b64733ed31c7a17ed96369c62

""" Continuous Random Variables - Prebuilt variables Contains ======== Arcsin Benini Beta BetaPrime Cauchy Chi ChiNoncentral ChiSquared Dagum Erlang Exponential FDistribution FisherZ Frechet Gamma GammaInverse Gumbel Gompertz Kumaraswamy Laplace Logistic LogNormal Maxwell Nakagami Normal Pareto QuadraticU RaisedCosine Rayleigh ShiftedGompertz StudentT Trapezoidal Triangular Uniform UniformSum VonMises Weibull WignerSemicircle """ from __future__ import print_function, division from sympy import (log, sqrt, pi, S, Dummy, Interval, sympify, gamma, Piecewise, And, Eq, binomial, factorial, Sum, floor, Abs, Lambda, Basic, lowergamma, erf, erfi, I, hyper, uppergamma, sinh, Ne, expint) from sympy import beta as beta_fn from sympy import cos, sin, exp, besseli, besselj, besselk from sympy.stats.crv import (SingleContinuousPSpace, SingleContinuousDistribution, ContinuousDistributionHandmade) from sympy.stats.rv import _value_check, RandomSymbol from sympy.matrices import MatrixBase from sympy.stats.joint_rv_types import multivariate_rv from sympy.stats.joint_rv import MarginalDistribution, JointPSpace, CompoundDistribution from sympy.external import import_module import random oo = S.Infinity __all__ = ['ContinuousRV', 'Arcsin', 'Benini', 'Beta', 'BetaPrime', 'Cauchy', 'Chi', 'ChiNoncentral', 'ChiSquared', 'Dagum', 'Erlang', 'Exponential', 'FDistribution', 'FisherZ', 'Frechet', 'Gamma', 'GammaInverse', 'Gompertz', 'Gumbel', 'Kumaraswamy', 'Laplace', 'Logistic', 'LogNormal', 'Maxwell', 'Nakagami', 'Normal', 'Pareto', 'QuadraticU', 'RaisedCosine', 'Rayleigh', 'StudentT', 'ShiftedGompertz', 'Trapezoidal', 'Triangular', 'Uniform', 'UniformSum', 'VonMises', 'Weibull', 'WignerSemicircle' ] def ContinuousRV(symbol, density, set=Interval(-oo, oo)): """ Create a Continuous Random Variable given the following: -- a symbol -- a probability density function -- set on which the pdf is valid (defaults to entire real line) Returns a RandomSymbol. Many common continuous random variable types are already implemented. This function should be necessary only very rarely. Examples ======== >>> from sympy import Symbol, sqrt, exp, pi >>> from sympy.stats import ContinuousRV, P, E >>> x = Symbol("x") >>> pdf = sqrt(2)*exp(-x**2/2)/(2*sqrt(pi)) # Normal distribution >>> X = ContinuousRV(x, pdf) >>> E(X) 0 >>> P(X>0) 1/2 """ pdf = Piecewise((density, set.as_relational(symbol)), (0, True)) pdf = Lambda(symbol, pdf) dist = ContinuousDistributionHandmade(pdf, set) return SingleContinuousPSpace(symbol, dist).value def rv(symbol, cls, args): args = list(map(sympify, args)) dist = cls(*args) dist.check(*args) pspace = SingleContinuousPSpace(symbol, dist) if any(isinstance(arg, RandomSymbol) for arg in args): pspace = JointPSpace(symbol, CompoundDistribution(dist)) return pspace.value ######################################## # Continuous Probability Distributions # ######################################## #------------------------------------------------------------------------------- # Arcsin distribution ---------------------------------------------------------- class ArcsinDistribution(SingleContinuousDistribution): _argnames = ('a', 'b') def pdf(self, x): return 1/(pi*sqrt((x - self.a)*(self.b - x))) def _cdf(self, x): from sympy import asin a, b = self.a, self.b return Piecewise( (S.Zero, x < a), (2*asin(sqrt((x - a)/(b - a)))/pi, x <= b), (S.One, True)) def Arcsin(name, a=0, b=1): r""" Create a Continuous Random Variable with an arcsin distribution. The density of the arcsin distribution is given by .. math:: f(x) := \frac{1}{\pi\sqrt{(x-a)(b-x)}} with :math:`x \in [a,b]`. It must hold that :math:`-\infty < a < b < \infty`. Parameters ========== a : Real number, the left interval boundary b : Real number, the right interval boundary Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Arcsin, density, cdf >>> from sympy import Symbol, simplify >>> a = Symbol("a", real=True) >>> b = Symbol("b", real=True) >>> z = Symbol("z") >>> X = Arcsin("x", a, b) >>> density(X)(z) 1/(pi*sqrt((-a + z)*(b - z))) >>> cdf(X)(z) Piecewise((0, a > z), (2*asin(sqrt((-a + z)/(-a + b)))/pi, b >= z), (1, True)) References ========== .. [1] https://en.wikipedia.org/wiki/Arcsine_distribution """ return rv(name, ArcsinDistribution, (a, b)) #------------------------------------------------------------------------------- # Benini distribution ---------------------------------------------------------- class BeniniDistribution(SingleContinuousDistribution): _argnames = ('alpha', 'beta', 'sigma') @property def set(self): return Interval(self.sigma, oo) def pdf(self, x): alpha, beta, sigma = self.alpha, self.beta, self.sigma return (exp(-alpha*log(x/sigma) - beta*log(x/sigma)**2) *(alpha/x + 2*beta*log(x/sigma)/x)) def _moment_generating_function(self, t): raise NotImplementedError('The moment generating function of the ' 'Benini distribution does not exist.') def Benini(name, alpha, beta, sigma): r""" Create a Continuous Random Variable with a Benini distribution. The density of the Benini distribution is given by .. math:: f(x) := e^{-\alpha\log{\frac{x}{\sigma}} -\beta\log^2\left[{\frac{x}{\sigma}}\right]} \left(\frac{\alpha}{x}+\frac{2\beta\log{\frac{x}{\sigma}}}{x}\right) This is a heavy-tailed distrubtion and is also known as the log-Rayleigh distribution. Parameters ========== alpha : Real number, `\alpha > 0`, a shape beta : Real number, `\beta > 0`, a shape sigma : Real number, `\sigma > 0`, a scale Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Benini, density >>> from sympy import Symbol, simplify, pprint >>> alpha = Symbol("alpha", positive=True) >>> beta = Symbol("beta", positive=True) >>> sigma = Symbol("sigma", positive=True) >>> z = Symbol("z") >>> X = Benini("x", alpha, beta, sigma) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) / / z \\ / z \ 2/ z \ | 2*beta*log|-----|| - alpha*log|-----| - beta*log |-----| |alpha \sigma/| \sigma/ \sigma/ |----- + -----------------|*e \ z z / References ========== .. [1] https://en.wikipedia.org/wiki/Benini_distribution .. [2] http://reference.wolfram.com/legacy/v8/ref/BeniniDistribution.html """ return rv(name, BeniniDistribution, (alpha, beta, sigma)) #------------------------------------------------------------------------------- # Beta distribution ------------------------------------------------------------ class BetaDistribution(SingleContinuousDistribution): _argnames = ('alpha', 'beta') set = Interval(0, 1) @staticmethod def check(alpha, beta): _value_check(alpha > 0, "Alpha must be positive") _value_check(beta > 0, "Beta must be positive") def pdf(self, x): alpha, beta = self.alpha, self.beta return x**(alpha - 1) * (1 - x)**(beta - 1) / beta_fn(alpha, beta) def sample(self): return random.betavariate(self.alpha, self.beta) def _characteristic_function(self, t): return hyper((self.alpha,), (self.alpha + self.beta,), I*t) def _moment_generating_function(self, t): return hyper((self.alpha,), (self.alpha + self.beta,), t) def Beta(name, alpha, beta): r""" Create a Continuous Random Variable with a Beta distribution. The density of the Beta distribution is given by .. math:: f(x) := \frac{x^{\alpha-1}(1-x)^{\beta-1}} {\mathrm{B}(\alpha,\beta)} with :math:`x \in [0,1]`. Parameters ========== alpha : Real number, `\alpha > 0`, a shape beta : Real number, `\beta > 0`, a shape Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Beta, density, E, variance >>> from sympy import Symbol, simplify, pprint, expand_func >>> alpha = Symbol("alpha", positive=True) >>> beta = Symbol("beta", positive=True) >>> z = Symbol("z") >>> X = Beta("x", alpha, beta) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) alpha - 1 beta - 1 z *(-z + 1) --------------------------- B(alpha, beta) >>> expand_func(simplify(E(X, meijerg=True))) alpha/(alpha + beta) >>> simplify(variance(X, meijerg=True)) #doctest: +SKIP alpha*beta/((alpha + beta)**2*(alpha + beta + 1)) References ========== .. [1] https://en.wikipedia.org/wiki/Beta_distribution .. [2] http://mathworld.wolfram.com/BetaDistribution.html """ return rv(name, BetaDistribution, (alpha, beta)) #------------------------------------------------------------------------------- # Beta prime distribution ------------------------------------------------------ class BetaPrimeDistribution(SingleContinuousDistribution): _argnames = ('alpha', 'beta') set = Interval(0, oo) def pdf(self, x): alpha, beta = self.alpha, self.beta return x**(alpha - 1)*(1 + x)**(-alpha - beta)/beta_fn(alpha, beta) def BetaPrime(name, alpha, beta): r""" Create a continuous random variable with a Beta prime distribution. The density of the Beta prime distribution is given by .. math:: f(x) := \frac{x^{\alpha-1} (1+x)^{-\alpha -\beta}}{B(\alpha,\beta)} with :math:`x > 0`. Parameters ========== alpha : Real number, `\alpha > 0`, a shape beta : Real number, `\beta > 0`, a shape Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import BetaPrime, density >>> from sympy import Symbol, pprint >>> alpha = Symbol("alpha", positive=True) >>> beta = Symbol("beta", positive=True) >>> z = Symbol("z") >>> X = BetaPrime("x", alpha, beta) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) alpha - 1 -alpha - beta z *(z + 1) ------------------------------- B(alpha, beta) References ========== .. [1] https://en.wikipedia.org/wiki/Beta_prime_distribution .. [2] http://mathworld.wolfram.com/BetaPrimeDistribution.html """ return rv(name, BetaPrimeDistribution, (alpha, beta)) #------------------------------------------------------------------------------- # Cauchy distribution ---------------------------------------------------------- class CauchyDistribution(SingleContinuousDistribution): _argnames = ('x0', 'gamma') def pdf(self, x): return 1/(pi*self.gamma*(1 + ((x - self.x0)/self.gamma)**2)) def _characteristic_function(self, t): return exp(self.x0 * I * t - self.gamma * Abs(t)) def _moment_generating_function(self, t): raise NotImplementedError("The moment generating function for the " "Cauchy distribution does not exist.") def Cauchy(name, x0, gamma): r""" Create a continuous random variable with a Cauchy distribution. The density of the Cauchy distribution is given by .. math:: f(x) := \frac{1}{\pi} \arctan\left(\frac{x-x_0}{\gamma}\right) +\frac{1}{2} Parameters ========== x0 : Real number, the location gamma : Real number, `\gamma > 0`, the scale Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Cauchy, density >>> from sympy import Symbol >>> x0 = Symbol("x0") >>> gamma = Symbol("gamma", positive=True) >>> z = Symbol("z") >>> X = Cauchy("x", x0, gamma) >>> density(X)(z) 1/(pi*gamma*(1 + (-x0 + z)**2/gamma**2)) References ========== .. [1] https://en.wikipedia.org/wiki/Cauchy_distribution .. [2] http://mathworld.wolfram.com/CauchyDistribution.html """ return rv(name, CauchyDistribution, (x0, gamma)) #------------------------------------------------------------------------------- # Chi distribution ------------------------------------------------------------- class ChiDistribution(SingleContinuousDistribution): _argnames = ('k',) set = Interval(0, oo) def pdf(self, x): return 2**(1 - self.k/2)*x**(self.k - 1)*exp(-x**2/2)/gamma(self.k/2) def _characteristic_function(self, t): k = self.k part_1 = hyper((k/2,), (S(1)/2,), -t**2/2) part_2 = I*t*sqrt(2)*gamma((k+1)/2)/gamma(k/2) part_3 = hyper(((k+1)/2,), (S(3)/2,), -t**2/2) return part_1 + part_2*part_3 def _moment_generating_function(self, t): k = self.k part_1 = hyper((k / 2,), (S(1) / 2,), t ** 2 / 2) part_2 = t * sqrt(2) * gamma((k + 1) / 2) / gamma(k / 2) part_3 = hyper(((k + 1) / 2,), (S(3) / 2,), t ** 2 / 2) return part_1 + part_2 * part_3 def Chi(name, k): r""" Create a continuous random variable with a Chi distribution. The density of the Chi distribution is given by .. math:: f(x) := \frac{2^{1-k/2}x^{k-1}e^{-x^2/2}}{\Gamma(k/2)} with :math:`x \geq 0`. Parameters ========== k : A positive Integer, `k > 0`, the number of degrees of freedom Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Chi, density, E, std >>> from sympy import Symbol, simplify >>> k = Symbol("k", integer=True) >>> z = Symbol("z") >>> X = Chi("x", k) >>> density(X)(z) 2**(-k/2 + 1)*z**(k - 1)*exp(-z**2/2)/gamma(k/2) References ========== .. [1] https://en.wikipedia.org/wiki/Chi_distribution .. [2] http://mathworld.wolfram.com/ChiDistribution.html """ return rv(name, ChiDistribution, (k,)) #------------------------------------------------------------------------------- # Non-central Chi distribution ------------------------------------------------- class ChiNoncentralDistribution(SingleContinuousDistribution): _argnames = ('k', 'l') set = Interval(0, oo) def pdf(self, x): k, l = self.k, self.l return exp(-(x**2+l**2)/2)*x**k*l / (l*x)**(k/2) * besseli(k/2-1, l*x) def ChiNoncentral(name, k, l): r""" Create a continuous random variable with a non-central Chi distribution. The density of the non-central Chi distribution is given by .. math:: f(x) := \frac{e^{-(x^2+\lambda^2)/2} x^k\lambda} {(\lambda x)^{k/2}} I_{k/2-1}(\lambda x) with `x \geq 0`. Here, `I_\nu (x)` is the :ref:`modified Bessel function of the first kind <besseli>`. Parameters ========== k : A positive Integer, `k > 0`, the number of degrees of freedom l : Shift parameter Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import ChiNoncentral, density, E, std >>> from sympy import Symbol, simplify >>> k = Symbol("k", integer=True) >>> l = Symbol("l") >>> z = Symbol("z") >>> X = ChiNoncentral("x", k, l) >>> density(X)(z) l*z**k*(l*z)**(-k/2)*exp(-l**2/2 - z**2/2)*besseli(k/2 - 1, l*z) References ========== .. [1] https://en.wikipedia.org/wiki/Noncentral_chi_distribution """ return rv(name, ChiNoncentralDistribution, (k, l)) #------------------------------------------------------------------------------- # Chi squared distribution ----------------------------------------------------- class ChiSquaredDistribution(SingleContinuousDistribution): _argnames = ('k',) set = Interval(0, oo) def pdf(self, x): k = self.k return 1/(2**(k/2)*gamma(k/2))*x**(k/2 - 1)*exp(-x/2) def _cdf(self, x): k = self.k return Piecewise( (S.One/gamma(k/2)*lowergamma(k/2, x/2), x >= 0), (0, True) ) def _characteristic_function(self, t): return (1 - 2*I*t)**(-self.k/2) def _moment_generating_function(self, t): return (1 - 2*t)**(-self.k/2) def ChiSquared(name, k): r""" Create a continuous random variable with a Chi-squared distribution. The density of the Chi-squared distribution is given by .. math:: f(x) := \frac{1}{2^{\frac{k}{2}}\Gamma\left(\frac{k}{2}\right)} x^{\frac{k}{2}-1} e^{-\frac{x}{2}} with :math:`x \geq 0`. Parameters ========== k : A positive Integer, `k > 0`, the number of degrees of freedom Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import ChiSquared, density, E, variance >>> from sympy import Symbol, simplify, gammasimp, expand_func >>> k = Symbol("k", integer=True, positive=True) >>> z = Symbol("z") >>> X = ChiSquared("x", k) >>> density(X)(z) 2**(-k/2)*z**(k/2 - 1)*exp(-z/2)/gamma(k/2) >>> gammasimp(E(X)) k >>> simplify(expand_func(variance(X))) 2*k References ========== .. [1] https://en.wikipedia.org/wiki/Chi_squared_distribution .. [2] http://mathworld.wolfram.com/Chi-SquaredDistribution.html """ return rv(name, ChiSquaredDistribution, (k, )) #------------------------------------------------------------------------------- # Dagum distribution ----------------------------------------------------------- class DagumDistribution(SingleContinuousDistribution): _argnames = ('p', 'a', 'b') def pdf(self, x): p, a, b = self.p, self.a, self.b return a*p/x*((x/b)**(a*p)/(((x/b)**a + 1)**(p + 1))) def _cdf(self, x): p, a, b = self.p, self.a, self.b return Piecewise(((S.One + (S(x)/b)**-a)**-p, x>=0), (S.Zero, True)) def Dagum(name, p, a, b): r""" Create a continuous random variable with a Dagum distribution. The density of the Dagum distribution is given by .. math:: f(x) := \frac{a p}{x} \left( \frac{\left(\tfrac{x}{b}\right)^{a p}} {\left(\left(\tfrac{x}{b}\right)^a + 1 \right)^{p+1}} \right) with :math:`x > 0`. Parameters ========== p : Real number, `p > 0`, a shape a : Real number, `a > 0`, a shape b : Real number, `b > 0`, a scale Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Dagum, density, cdf >>> from sympy import Symbol, simplify >>> p = Symbol("p", positive=True) >>> b = Symbol("b", positive=True) >>> a = Symbol("a", positive=True) >>> z = Symbol("z") >>> X = Dagum("x", p, a, b) >>> density(X)(z) a*p*(z/b)**(a*p)*((z/b)**a + 1)**(-p - 1)/z >>> cdf(X)(z) Piecewise(((1 + (z/b)**(-a))**(-p), z >= 0), (0, True)) References ========== .. [1] https://en.wikipedia.org/wiki/Dagum_distribution """ return rv(name, DagumDistribution, (p, a, b)) #------------------------------------------------------------------------------- # Erlang distribution ---------------------------------------------------------- def Erlang(name, k, l): r""" Create a continuous random variable with an Erlang distribution. The density of the Erlang distribution is given by .. math:: f(x) := \frac{\lambda^k x^{k-1} e^{-\lambda x}}{(k-1)!} with :math:`x \in [0,\infty]`. Parameters ========== k : Integer l : Real number, `\lambda > 0`, the rate Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Erlang, density, cdf, E, variance >>> from sympy import Symbol, simplify, pprint >>> k = Symbol("k", integer=True, positive=True) >>> l = Symbol("l", positive=True) >>> z = Symbol("z") >>> X = Erlang("x", k, l) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) k k - 1 -l*z l *z *e --------------- Gamma(k) >>> C = cdf(X, meijerg=True)(z) >>> pprint(C, use_unicode=False) / -2*I*pi*k |k*e *lowergamma(k, l*z) |------------------------------- for z >= 0 < Gamma(k + 1) | | 0 otherwise \ >>> simplify(E(X)) k/l >>> simplify(variance(X)) k/l**2 References ========== .. [1] https://en.wikipedia.org/wiki/Erlang_distribution .. [2] http://mathworld.wolfram.com/ErlangDistribution.html """ return rv(name, GammaDistribution, (k, S.One/l)) #------------------------------------------------------------------------------- # Exponential distribution ----------------------------------------------------- class ExponentialDistribution(SingleContinuousDistribution): _argnames = ('rate',) set = Interval(0, oo) @staticmethod def check(rate): _value_check(rate > 0, "Rate must be positive.") def pdf(self, x): return self.rate * exp(-self.rate*x) def sample(self): return random.expovariate(self.rate) def _cdf(self, x): return Piecewise( (S.One - exp(-self.rate*x), x >= 0), (0, True), ) def _characteristic_function(self, t): rate = self.rate return rate / (rate - I*t) def _moment_generating_function(self, t): rate = self.rate return rate / (rate - t) def Exponential(name, rate): r""" Create a continuous random variable with an Exponential distribution. The density of the exponential distribution is given by .. math:: f(x) := \lambda \exp(-\lambda x) with `x > 0`. Note that the expected value is `1/\lambda`. Parameters ========== rate : A positive Real number, `\lambda > 0`, the rate (or inverse scale/inverse mean) Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Exponential, density, cdf, E >>> from sympy.stats import variance, std, skewness >>> from sympy import Symbol >>> l = Symbol("lambda", positive=True) >>> z = Symbol("z") >>> X = Exponential("x", l) >>> density(X)(z) lambda*exp(-lambda*z) >>> cdf(X)(z) Piecewise((1 - exp(-lambda*z), z >= 0), (0, True)) >>> E(X) 1/lambda >>> variance(X) lambda**(-2) >>> skewness(X) 2 >>> X = Exponential('x', 10) >>> density(X)(z) 10*exp(-10*z) >>> E(X) 1/10 >>> std(X) 1/10 References ========== .. [1] https://en.wikipedia.org/wiki/Exponential_distribution .. [2] http://mathworld.wolfram.com/ExponentialDistribution.html """ return rv(name, ExponentialDistribution, (rate, )) #------------------------------------------------------------------------------- # F distribution --------------------------------------------------------------- class FDistributionDistribution(SingleContinuousDistribution): _argnames = ('d1', 'd2') set = Interval(0, oo) def pdf(self, x): d1, d2 = self.d1, self.d2 return (sqrt((d1*x)**d1*d2**d2 / (d1*x+d2)**(d1+d2)) / (x * beta_fn(d1/2, d2/2))) def _moment_generating_function(self, t): raise NotImplementedError('The moment generating function for the ' 'F-distribution does not exist.') def FDistribution(name, d1, d2): r""" Create a continuous random variable with a F distribution. The density of the F distribution is given by .. math:: f(x) := \frac{\sqrt{\frac{(d_1 x)^{d_1} d_2^{d_2}} {(d_1 x + d_2)^{d_1 + d_2}}}} {x \mathrm{B} \left(\frac{d_1}{2}, \frac{d_2}{2}\right)} with :math:`x > 0`. Parameters ========== d1 : `d_1 > 0`, where d_1 is the degrees of freedom (n_1 - 1) d2 : `d_2 > 0`, where d_2 is the degrees of freedom (n_2 - 1) Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import FDistribution, density >>> from sympy import Symbol, simplify, pprint >>> d1 = Symbol("d1", positive=True) >>> d2 = Symbol("d2", positive=True) >>> z = Symbol("z") >>> X = FDistribution("x", d1, d2) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) d2 -- ______________________________ 2 / d1 -d1 - d2 d2 *\/ (d1*z) *(d1*z + d2) -------------------------------------- /d1 d2\ z*B|--, --| \2 2 / References ========== .. [1] https://en.wikipedia.org/wiki/F-distribution .. [2] http://mathworld.wolfram.com/F-Distribution.html """ return rv(name, FDistributionDistribution, (d1, d2)) #------------------------------------------------------------------------------- # Fisher Z distribution -------------------------------------------------------- class FisherZDistribution(SingleContinuousDistribution): _argnames = ('d1', 'd2') def pdf(self, x): d1, d2 = self.d1, self.d2 return (2*d1**(d1/2)*d2**(d2/2) / beta_fn(d1/2, d2/2) * exp(d1*x) / (d1*exp(2*x)+d2)**((d1+d2)/2)) def FisherZ(name, d1, d2): r""" Create a Continuous Random Variable with an Fisher's Z distribution. The density of the Fisher's Z distribution is given by .. math:: f(x) := \frac{2d_1^{d_1/2} d_2^{d_2/2}} {\mathrm{B}(d_1/2, d_2/2)} \frac{e^{d_1z}}{\left(d_1e^{2z}+d_2\right)^{\left(d_1+d_2\right)/2}} .. TODO - What is the difference between these degrees of freedom? Parameters ========== d1 : `d_1 > 0`, degree of freedom d2 : `d_2 > 0`, degree of freedom Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import FisherZ, density >>> from sympy import Symbol, simplify, pprint >>> d1 = Symbol("d1", positive=True) >>> d2 = Symbol("d2", positive=True) >>> z = Symbol("z") >>> X = FisherZ("x", d1, d2) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) d1 d2 d1 d2 - -- - -- -- -- 2 2 2 2 / 2*z \ d1*z 2*d1 *d2 *\d1*e + d2/ *e ----------------------------------------- /d1 d2\ B|--, --| \2 2 / References ========== .. [1] https://en.wikipedia.org/wiki/Fisher%27s_z-distribution .. [2] http://mathworld.wolfram.com/Fishersz-Distribution.html """ return rv(name, FisherZDistribution, (d1, d2)) #------------------------------------------------------------------------------- # Frechet distribution --------------------------------------------------------- class FrechetDistribution(SingleContinuousDistribution): _argnames = ('a', 's', 'm') set = Interval(0, oo) def __new__(cls, a, s=1, m=0): a, s, m = list(map(sympify, (a, s, m))) return Basic.__new__(cls, a, s, m) def pdf(self, x): a, s, m = self.a, self.s, self.m return a/s * ((x-m)/s)**(-1-a) * exp(-((x-m)/s)**(-a)) def _cdf(self, x): a, s, m = self.a, self.s, self.m return Piecewise((exp(-((x-m)/s)**(-a)), x >= m), (S.Zero, True)) def Frechet(name, a, s=1, m=0): r""" Create a continuous random variable with a Frechet distribution. The density of the Frechet distribution is given by .. math:: f(x) := \frac{\alpha}{s} \left(\frac{x-m}{s}\right)^{-1-\alpha} e^{-(\frac{x-m}{s})^{-\alpha}} with :math:`x \geq m`. Parameters ========== a : Real number, :math:`a \in \left(0, \infty\right)` the shape s : Real number, :math:`s \in \left(0, \infty\right)` the scale m : Real number, :math:`m \in \left(-\infty, \infty\right)` the minimum Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Frechet, density, E, std, cdf >>> from sympy import Symbol, simplify >>> a = Symbol("a", positive=True) >>> s = Symbol("s", positive=True) >>> m = Symbol("m", real=True) >>> z = Symbol("z") >>> X = Frechet("x", a, s, m) >>> density(X)(z) a*((-m + z)/s)**(-a - 1)*exp(-((-m + z)/s)**(-a))/s >>> cdf(X)(z) Piecewise((exp(-((-m + z)/s)**(-a)), m <= z), (0, True)) References ========== .. [1] https://en.wikipedia.org/wiki/Fr%C3%A9chet_distribution """ return rv(name, FrechetDistribution, (a, s, m)) #------------------------------------------------------------------------------- # Gamma distribution ----------------------------------------------------------- class GammaDistribution(SingleContinuousDistribution): _argnames = ('k', 'theta') set = Interval(0, oo) @staticmethod def check(k, theta): _value_check(k > 0, "k must be positive") _value_check(theta > 0, "Theta must be positive") def pdf(self, x): k, theta = self.k, self.theta return x**(k - 1) * exp(-x/theta) / (gamma(k)*theta**k) def sample(self): return random.gammavariate(self.k, self.theta) def _cdf(self, x): k, theta = self.k, self.theta return Piecewise( (lowergamma(k, S(x)/theta)/gamma(k), x > 0), (S.Zero, True)) def _characteristic_function(self, t): return (1 - self.theta*I*t)**(-self.k) def _moment_generating_function(self, t): return (1- self.theta*t)**(-self.k) def Gamma(name, k, theta): r""" Create a continuous random variable with a Gamma distribution. The density of the Gamma distribution is given by .. math:: f(x) := \frac{1}{\Gamma(k) \theta^k} x^{k - 1} e^{-\frac{x}{\theta}} with :math:`x \in [0,1]`. Parameters ========== k : Real number, `k > 0`, a shape theta : Real number, `\theta > 0`, a scale Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Gamma, density, cdf, E, variance >>> from sympy import Symbol, pprint, simplify >>> k = Symbol("k", positive=True) >>> theta = Symbol("theta", positive=True) >>> z = Symbol("z") >>> X = Gamma("x", k, theta) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) -z ----- -k k - 1 theta theta *z *e --------------------- Gamma(k) >>> C = cdf(X, meijerg=True)(z) >>> pprint(C, use_unicode=False) / / z \ |k*lowergamma|k, -----| | \ theta/ <---------------------- for z >= 0 | Gamma(k + 1) | \ 0 otherwise >>> E(X) k*theta >>> V = simplify(variance(X)) >>> pprint(V, use_unicode=False) 2 k*theta References ========== .. [1] https://en.wikipedia.org/wiki/Gamma_distribution .. [2] http://mathworld.wolfram.com/GammaDistribution.html """ return rv(name, GammaDistribution, (k, theta)) #------------------------------------------------------------------------------- # Inverse Gamma distribution --------------------------------------------------- class GammaInverseDistribution(SingleContinuousDistribution): _argnames = ('a', 'b') set = Interval(0, oo) @staticmethod def check(a, b): _value_check(a > 0, "alpha must be positive") _value_check(b > 0, "beta must be positive") def pdf(self, x): a, b = self.a, self.b return b**a/gamma(a) * x**(-a-1) * exp(-b/x) def _cdf(self, x): a, b = self.a, self.b return Piecewise((uppergamma(a,b/x)/gamma(a), x > 0), (S.Zero, True)) def sample(self): scipy = import_module('scipy') if scipy: from scipy.stats import invgamma return invgamma.rvs(float(self.a), 0, float(self.b)) else: raise NotImplementedError('Sampling the inverse Gamma Distribution requires Scipy.') def _characteristic_function(self, t): a, b = self.a, self.b return 2 * (-I*b*t)**(a/2) * besselk(sqrt(-4*I*b*t)) / gamma(a) def _moment_generating_function(self, t): raise NotImplementedError('The moment generating function for the ' 'gamma inverse distribution does not exist.') def GammaInverse(name, a, b): r""" Create a continuous random variable with an inverse Gamma distribution. The density of the inverse Gamma distribution is given by .. math:: f(x) := \frac{\beta^\alpha}{\Gamma(\alpha)} x^{-\alpha - 1} \exp\left(\frac{-\beta}{x}\right) with :math:`x > 0`. Parameters ========== a : Real number, `a > 0` a shape b : Real number, `b > 0` a scale Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import GammaInverse, density, cdf, E, variance >>> from sympy import Symbol, pprint >>> a = Symbol("a", positive=True) >>> b = Symbol("b", positive=True) >>> z = Symbol("z") >>> X = GammaInverse("x", a, b) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) -b --- a -a - 1 z b *z *e --------------- Gamma(a) >>> cdf(X)(z) Piecewise((uppergamma(a, b/z)/gamma(a), z > 0), (0, True)) References ========== .. [1] https://en.wikipedia.org/wiki/Inverse-gamma_distribution """ return rv(name, GammaInverseDistribution, (a, b)) #------------------------------------------------------------------------------- # Gumbel distribution -------------------------------------------------------- class GumbelDistribution(SingleContinuousDistribution): _argnames = ('beta', 'mu') set = Interval(-oo, oo) def pdf(self, x): beta, mu = self.beta, self.mu return (1/beta)*exp(-((x-mu)/beta)+exp(-((x-mu)/beta))) def _characteristic_function(self, t): return gamma(1 - I*self.beta*t) * exp(I*self.mu*t) def _moment_generating_function(self, t): return gamma(1 - self.beta*t) * exp(I*self.mu*t) def Gumbel(name, beta, mu): r""" Create a Continuous Random Variable with Gumbel distribution. The density of the Gumbel distribution is given by .. math:: f(x) := \exp \left( -exp \left( x + \exp \left( -x \right) \right) \right) with ::math 'x \in [ - \inf, \inf ]'. Parameters ========== mu: Real number, 'mu' is a location beta: Real number, 'beta > 0' is a scale Returns ========== A RandomSymbol Examples ========== >>> from sympy.stats import Gumbel, density, E, variance >>> from sympy import Symbol, simplify, pprint >>> x = Symbol("x") >>> mu = Symbol("mu") >>> beta = Symbol("beta", positive=True) >>> X = Gumbel("x", beta, mu) >>> density(X)(x) exp(exp(-(-mu + x)/beta) - (-mu + x)/beta)/beta References ========== .. [1] http://mathworld.wolfram.com/GumbelDistribution.html .. [2] https://en.wikipedia.org/wiki/Gumbel_distribution """ return rv(name, GumbelDistribution, (beta, mu)) #------------------------------------------------------------------------------- # Gompertz distribution -------------------------------------------------------- class GompertzDistribution(SingleContinuousDistribution): _argnames = ('b', 'eta') set = Interval(0, oo) @staticmethod def check(b, eta): _value_check(b > 0, "b must be positive") _value_check(eta > 0, "eta must be positive") def pdf(self, x): eta, b = self.eta, self.b return b*eta*exp(b*x)*exp(eta)*exp(-eta*exp(b*x)) def _moment_generating_function(self, t): eta, b = self.eta, self.b return eta * exp(eta) * expint(t/b, eta) def Gompertz(name, b, eta): r""" Create a Continuous Random Variable with Gompertz distribution. The density of the Gompertz distribution is given by .. math:: f(x) := b \eta e^{b x} e^{\eta} \exp \left(-\eta e^{bx} \right) with :math: 'x \in [0, \inf)'. Parameters ========== b: Real number, 'b > 0' a scale eta: Real number, 'eta > 0' a shape Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Gompertz, density, E, variance >>> from sympy import Symbol, simplify, pprint >>> b = Symbol("b", positive=True) >>> eta = Symbol("eta", positive=True) >>> z = Symbol("z") >>> X = Gompertz("x", b, eta) >>> density(X)(z) b*eta*exp(eta)*exp(b*z)*exp(-eta*exp(b*z)) References ========== .. [1] https://en.wikipedia.org/wiki/Gompertz_distribution """ return rv(name, GompertzDistribution, (b, eta)) #------------------------------------------------------------------------------- # Kumaraswamy distribution ----------------------------------------------------- class KumaraswamyDistribution(SingleContinuousDistribution): _argnames = ('a', 'b') set = Interval(0, oo) @staticmethod def check(a, b): _value_check(a > 0, "a must be positive") _value_check(b > 0, "b must be positive") def pdf(self, x): a, b = self.a, self.b return a * b * x**(a-1) * (1-x**a)**(b-1) def _cdf(self, x): a, b = self.a, self.b return Piecewise( (S.Zero, x < S.Zero), (1 - (1 - x**a)**b, x <= S.One), (S.One, True)) def Kumaraswamy(name, a, b): r""" Create a Continuous Random Variable with a Kumaraswamy distribution. The density of the Kumaraswamy distribution is given by .. math:: f(x) := a b x^{a-1} (1-x^a)^{b-1} with :math:`x \in [0,1]`. Parameters ========== a : Real number, `a > 0` a shape b : Real number, `b > 0` a shape Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Kumaraswamy, density, E, variance, cdf >>> from sympy import Symbol, simplify, pprint >>> a = Symbol("a", positive=True) >>> b = Symbol("b", positive=True) >>> z = Symbol("z") >>> X = Kumaraswamy("x", a, b) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) b - 1 a - 1 / a \ a*b*z *\- z + 1/ >>> cdf(X)(z) Piecewise((0, z < 0), (-(-z**a + 1)**b + 1, z <= 1), (1, True)) References ========== .. [1] https://en.wikipedia.org/wiki/Kumaraswamy_distribution """ return rv(name, KumaraswamyDistribution, (a, b)) #------------------------------------------------------------------------------- # Laplace distribution --------------------------------------------------------- class LaplaceDistribution(SingleContinuousDistribution): _argnames = ('mu', 'b') def pdf(self, x): mu, b = self.mu, self.b return 1/(2*b)*exp(-Abs(x - mu)/b) def _cdf(self, x): mu, b = self.mu, self.b return Piecewise( (S.Half*exp((x - mu)/b), x < mu), (S.One - S.Half*exp(-(x - mu)/b), x >= mu) ) def _characteristic_function(self, t): return exp(self.mu*I*t) / (1 + self.b**2*t**2) def _moment_generating_function(self, t): return exp(self.mu*t) / (1 - self.b**2*t**2) def Laplace(name, mu, b): r""" Create a continuous random variable with a Laplace distribution. The density of the Laplace distribution is given by .. math:: f(x) := \frac{1}{2 b} \exp \left(-\frac{|x-\mu|}b \right) Parameters ========== mu : Real number or a list/matrix, the location (mean) or the location vector b : Real number or a positive definite matrix, representing a scale or the covariance matrix. Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Laplace, density, cdf >>> from sympy import Symbol, pprint >>> mu = Symbol("mu") >>> b = Symbol("b", positive=True) >>> z = Symbol("z") >>> X = Laplace("x", mu, b) >>> density(X)(z) exp(-Abs(mu - z)/b)/(2*b) >>> cdf(X)(z) Piecewise((exp((-mu + z)/b)/2, mu > z), (-exp((mu - z)/b)/2 + 1, True)) >>> L = Laplace('L', [1, 2], [[1, 0], [0, 1]]) >>> pprint(density(L)(1, 2), use_unicode=False) 5 / ____\ e *besselk\0, \/ 35 / --------------------- pi References ========== .. [1] https://en.wikipedia.org/wiki/Laplace_distribution .. [2] http://mathworld.wolfram.com/LaplaceDistribution.html """ if isinstance(mu, (list, MatrixBase)) and\ isinstance(b, (list, MatrixBase)): from sympy.stats.joint_rv_types import MultivariateLaplaceDistribution return multivariate_rv( MultivariateLaplaceDistribution, name, mu, b) return rv(name, LaplaceDistribution, (mu, b)) #------------------------------------------------------------------------------- # Logistic distribution -------------------------------------------------------- class LogisticDistribution(SingleContinuousDistribution): _argnames = ('mu', 's') def pdf(self, x): mu, s = self.mu, self.s return exp(-(x - mu)/s)/(s*(1 + exp(-(x - mu)/s))**2) def _cdf(self, x): mu, s = self.mu, self.s return S.One/(1 + exp(-(x - mu)/s)) def _characteristic_function(self, t): return Piecewise((exp(I*t*self.mu) * pi*self.s*t / sinh(pi*self.s*t), Ne(t, 0)), (S.One, True)) def _moment_generating_function(self, t): return exp(self.mu*t) * Beta(1 - self.s*t, 1 + self.s*t) def Logistic(name, mu, s): r""" Create a continuous random variable with a logistic distribution. The density of the logistic distribution is given by .. math:: f(x) := \frac{e^{-(x-\mu)/s}} {s\left(1+e^{-(x-\mu)/s}\right)^2} Parameters ========== mu : Real number, the location (mean) s : Real number, `s > 0` a scale Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Logistic, density, cdf >>> from sympy import Symbol >>> mu = Symbol("mu", real=True) >>> s = Symbol("s", positive=True) >>> z = Symbol("z") >>> X = Logistic("x", mu, s) >>> density(X)(z) exp((mu - z)/s)/(s*(exp((mu - z)/s) + 1)**2) >>> cdf(X)(z) 1/(exp((mu - z)/s) + 1) References ========== .. [1] https://en.wikipedia.org/wiki/Logistic_distribution .. [2] http://mathworld.wolfram.com/LogisticDistribution.html """ return rv(name, LogisticDistribution, (mu, s)) #------------------------------------------------------------------------------- # Log Normal distribution ------------------------------------------------------ class LogNormalDistribution(SingleContinuousDistribution): _argnames = ('mean', 'std') set = Interval(0, oo) def pdf(self, x): mean, std = self.mean, self.std return exp(-(log(x) - mean)**2 / (2*std**2)) / (x*sqrt(2*pi)*std) def sample(self): return random.lognormvariate(self.mean, self.std) def _cdf(self, x): mean, std = self.mean, self.std return Piecewise( (S.Half + S.Half*erf((log(x) - mean)/sqrt(2)/std), x > 0), (S.Zero, True) ) def _moment_generating_function(self, t): raise NotImplementedError('Moment generating function of the log-normal distribution is not defined.') def LogNormal(name, mean, std): r""" Create a continuous random variable with a log-normal distribution. The density of the log-normal distribution is given by .. math:: f(x) := \frac{1}{x\sqrt{2\pi\sigma^2}} e^{-\frac{\left(\ln x-\mu\right)^2}{2\sigma^2}} with :math:`x \geq 0`. Parameters ========== mu : Real number, the log-scale sigma : Real number, :math:`\sigma^2 > 0` a shape Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import LogNormal, density >>> from sympy import Symbol, simplify, pprint >>> mu = Symbol("mu", real=True) >>> sigma = Symbol("sigma", positive=True) >>> z = Symbol("z") >>> X = LogNormal("x", mu, sigma) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) 2 -(-mu + log(z)) ----------------- 2 ___ 2*sigma \/ 2 *e ------------------------ ____ 2*\/ pi *sigma*z >>> X = LogNormal('x', 0, 1) # Mean 0, standard deviation 1 >>> density(X)(z) sqrt(2)*exp(-log(z)**2/2)/(2*sqrt(pi)*z) References ========== .. [1] https://en.wikipedia.org/wiki/Lognormal .. [2] http://mathworld.wolfram.com/LogNormalDistribution.html """ return rv(name, LogNormalDistribution, (mean, std)) #------------------------------------------------------------------------------- # Maxwell distribution --------------------------------------------------------- class MaxwellDistribution(SingleContinuousDistribution): _argnames = ('a',) set = Interval(0, oo) def pdf(self, x): a = self.a return sqrt(2/pi)*x**2*exp(-x**2/(2*a**2))/a**3 def Maxwell(name, a): r""" Create a continuous random variable with a Maxwell distribution. The density of the Maxwell distribution is given by .. math:: f(x) := \sqrt{\frac{2}{\pi}} \frac{x^2 e^{-x^2/(2a^2)}}{a^3} with :math:`x \geq 0`. .. TODO - what does the parameter mean? Parameters ========== a : Real number, `a > 0` Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Maxwell, density, E, variance >>> from sympy import Symbol, simplify >>> a = Symbol("a", positive=True) >>> z = Symbol("z") >>> X = Maxwell("x", a) >>> density(X)(z) sqrt(2)*z**2*exp(-z**2/(2*a**2))/(sqrt(pi)*a**3) >>> E(X) 2*sqrt(2)*a/sqrt(pi) >>> simplify(variance(X)) a**2*(-8 + 3*pi)/pi References ========== .. [1] https://en.wikipedia.org/wiki/Maxwell_distribution .. [2] http://mathworld.wolfram.com/MaxwellDistribution.html """ return rv(name, MaxwellDistribution, (a, )) #------------------------------------------------------------------------------- # Nakagami distribution -------------------------------------------------------- class NakagamiDistribution(SingleContinuousDistribution): _argnames = ('mu', 'omega') set = Interval(0, oo) def pdf(self, x): mu, omega = self.mu, self.omega return 2*mu**mu/(gamma(mu)*omega**mu)*x**(2*mu - 1)*exp(-mu/omega*x**2) def _cdf(self, x): mu, omega = self.mu, self.omega return Piecewise( (lowergamma(mu, (mu/omega)*x**2)/gamma(mu), x > 0), (S.Zero, True)) def Nakagami(name, mu, omega): r""" Create a continuous random variable with a Nakagami distribution. The density of the Nakagami distribution is given by .. math:: f(x) := \frac{2\mu^\mu}{\Gamma(\mu)\omega^\mu} x^{2\mu-1} \exp\left(-\frac{\mu}{\omega}x^2 \right) with :math:`x > 0`. Parameters ========== mu : Real number, `\mu \geq \frac{1}{2}` a shape omega : Real number, `\omega > 0`, the spread Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Nakagami, density, E, variance, cdf >>> from sympy import Symbol, simplify, pprint >>> mu = Symbol("mu", positive=True) >>> omega = Symbol("omega", positive=True) >>> z = Symbol("z") >>> X = Nakagami("x", mu, omega) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) 2 -mu*z ------- mu -mu 2*mu - 1 omega 2*mu *omega *z *e ---------------------------------- Gamma(mu) >>> simplify(E(X)) sqrt(mu)*sqrt(omega)*gamma(mu + 1/2)/gamma(mu + 1) >>> V = simplify(variance(X)) >>> pprint(V, use_unicode=False) 2 omega*Gamma (mu + 1/2) omega - ----------------------- Gamma(mu)*Gamma(mu + 1) >>> cdf(X)(z) Piecewise((lowergamma(mu, mu*z**2/omega)/gamma(mu), z > 0), (0, True)) References ========== .. [1] https://en.wikipedia.org/wiki/Nakagami_distribution """ return rv(name, NakagamiDistribution, (mu, omega)) #------------------------------------------------------------------------------- # Normal distribution ---------------------------------------------------------- class NormalDistribution(SingleContinuousDistribution): _argnames = ('mean', 'std') @staticmethod def check(mean, std): _value_check(std > 0, "Standard deviation must be positive") def pdf(self, x): return exp(-(x - self.mean)**2 / (2*self.std**2)) / (sqrt(2*pi)*self.std) def sample(self): return random.normalvariate(self.mean, self.std) def _cdf(self, x): mean, std = self.mean, self.std return erf(sqrt(2)*(-mean + x)/(2*std))/2 + S.Half def _characteristic_function(self, t): mean, std = self.mean, self.std return exp(I*mean*t - std**2*t**2/2) def _moment_generating_function(self, t): mean, std = self.mean, self.std return exp(mean*t + std**2*t**2/2) def Normal(name, mean, std): r""" Create a continuous random variable with a Normal distribution. The density of the Normal distribution is given by .. math:: f(x) := \frac{1}{\sigma\sqrt{2\pi}} e^{ -\frac{(x-\mu)^2}{2\sigma^2} } Parameters ========== mu : Real number or a list representing the mean or the mean vector sigma : Real number or a positive definite sqaure matrix, :math:`\sigma^2 > 0` the variance Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Normal, density, E, std, cdf, skewness >>> from sympy import Symbol, simplify, pprint, factor, together, factor_terms >>> mu = Symbol("mu") >>> sigma = Symbol("sigma", positive=True) >>> z = Symbol("z") >>> y = Symbol("y") >>> X = Normal("x", mu, sigma) >>> density(X)(z) sqrt(2)*exp(-(-mu + z)**2/(2*sigma**2))/(2*sqrt(pi)*sigma) >>> C = simplify(cdf(X))(z) # it needs a little more help... >>> pprint(C, use_unicode=False) / ___ \ |\/ 2 *(-mu + z)| erf|---------------| \ 2*sigma / 1 -------------------- + - 2 2 >>> simplify(skewness(X)) 0 >>> X = Normal("x", 0, 1) # Mean 0, standard deviation 1 >>> density(X)(z) sqrt(2)*exp(-z**2/2)/(2*sqrt(pi)) >>> E(2*X + 1) 1 >>> simplify(std(2*X + 1)) 2 >>> m = Normal('X', [1, 2], [[2, 1], [1, 2]]) >>> from sympy.stats.joint_rv import marginal_distribution >>> pprint(density(m)(y, z)) / y 1\ /2*y z\ / z \ / y 2*z \ |- - + -|*|--- - -| + |- - + 1|*|- - + --- - 1| ___ \ 2 2/ \ 3 3/ \ 2 / \ 3 3 / \/ 3 *e ------------------------------------------------------ 6*pi >>> marginal_distribution(m, m[0])(1) 1/(2*sqrt(pi)) References ========== .. [1] https://en.wikipedia.org/wiki/Normal_distribution .. [2] http://mathworld.wolfram.com/NormalDistributionFunction.html """ if isinstance(mean, (list, MatrixBase)) and\ isinstance(std, (list, MatrixBase)): from sympy.stats.joint_rv_types import MultivariateNormalDistribution return multivariate_rv( MultivariateNormalDistribution, name, mean, std) return rv(name, NormalDistribution, (mean, std)) #------------------------------------------------------------------------------- # Pareto distribution ---------------------------------------------------------- class ParetoDistribution(SingleContinuousDistribution): _argnames = ('xm', 'alpha') @property def set(self): return Interval(self.xm, oo) @staticmethod def check(xm, alpha): _value_check(xm > 0, "Xm must be positive") _value_check(alpha > 0, "Alpha must be positive") def pdf(self, x): xm, alpha = self.xm, self.alpha return alpha * xm**alpha / x**(alpha + 1) def sample(self): return random.paretovariate(self.alpha) def _cdf(self, x): xm, alpha = self.xm, self.alpha return Piecewise( (S.One - xm**alpha/x**alpha, x>=xm), (0, True), ) def _moment_generating_function(self, t): xm, alpha = self.xm, self.alpha return alpha * (-xm*t)**alpha * uppergamma(-alpha, -xm*t) def _characteristic_function(self, t): xm, alpha = self.xm, self.alpha return alpha * (-I * xm * t) ** alpha * uppergamma(-alpha, -I * xm * t) def Pareto(name, xm, alpha): r""" Create a continuous random variable with the Pareto distribution. The density of the Pareto distribution is given by .. math:: f(x) := \frac{\alpha\,x_m^\alpha}{x^{\alpha+1}} with :math:`x \in [x_m,\infty]`. Parameters ========== xm : Real number, `x_m > 0`, a scale alpha : Real number, `\alpha > 0`, a shape Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Pareto, density >>> from sympy import Symbol >>> xm = Symbol("xm", positive=True) >>> beta = Symbol("beta", positive=True) >>> z = Symbol("z") >>> X = Pareto("x", xm, beta) >>> density(X)(z) beta*xm**beta*z**(-beta - 1) References ========== .. [1] https://en.wikipedia.org/wiki/Pareto_distribution .. [2] http://mathworld.wolfram.com/ParetoDistribution.html """ return rv(name, ParetoDistribution, (xm, alpha)) #------------------------------------------------------------------------------- # QuadraticU distribution ------------------------------------------------------ class QuadraticUDistribution(SingleContinuousDistribution): _argnames = ('a', 'b') @property def set(self): return Interval(self.a, self.b) def pdf(self, x): a, b = self.a, self.b alpha = 12 / (b-a)**3 beta = (a+b) / 2 return Piecewise( (alpha * (x-beta)**2, And(a<=x, x<=b)), (S.Zero, True)) def _moment_generating_function(self, t): a, b = self.a, self.b return -3 * (exp(a*t) * (4 + (a**2 + 2*a*(-2 + b) + b**2) * t) - exp(b*t) * (4 + (-4*b + (a + b)**2) * t)) / ((a-b)**3 * t**2) def _characteristic_function(self, t): def _moment_generating_function(self, t): a, b = self.a, self.b return -3*I*(exp(I*a*t*exp(I*b*t)) * (4*I - (-4*b + (a+b)**2)*t)) / ((a-b)**3 * t**2) def QuadraticU(name, a, b): r""" Create a Continuous Random Variable with a U-quadratic distribution. The density of the U-quadratic distribution is given by .. math:: f(x) := \alpha (x-\beta)^2 with :math:`x \in [a,b]`. Parameters ========== a : Real number b : Real number, :math:`a < b` Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import QuadraticU, density, E, variance >>> from sympy import Symbol, simplify, factor, pprint >>> a = Symbol("a", real=True) >>> b = Symbol("b", real=True) >>> z = Symbol("z") >>> X = QuadraticU("x", a, b) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) / 2 | / a b \ |12*|- - - - + z| | \ 2 2 / <----------------- for And(b >= z, a <= z) | 3 | (-a + b) | \ 0 otherwise References ========== .. [1] https://en.wikipedia.org/wiki/U-quadratic_distribution """ return rv(name, QuadraticUDistribution, (a, b)) #------------------------------------------------------------------------------- # RaisedCosine distribution ---------------------------------------------------- class RaisedCosineDistribution(SingleContinuousDistribution): _argnames = ('mu', 's') @property def set(self): return Interval(self.mu - self.s, self.mu + self.s) @staticmethod def check(mu, s): _value_check(s > 0, "s must be positive") def pdf(self, x): mu, s = self.mu, self.s return Piecewise( ((1+cos(pi*(x-mu)/s)) / (2*s), And(mu-s<=x, x<=mu+s)), (S.Zero, True)) def _characteristic_function(self, t): mu, s = self.mu, self.s return Piecewise((exp(-I*pi*mu/s)/2, Eq(t, -pi/s)), (exp(I*pi*mu/s)/2, Eq(t, pi/s)), (pi**2*sin(s*t)*exp(I*mu*t) / (s*t*(pi**2 - s**2*t**2)), True)) def _moment_generating_function(self, t): mu, s = self.mu, self.s return pi**2 * sinh(s*t) * exp(mu*t) / (s*t*(pi**2 + s**2*t**2)) def RaisedCosine(name, mu, s): r""" Create a Continuous Random Variable with a raised cosine distribution. The density of the raised cosine distribution is given by .. math:: f(x) := \frac{1}{2s}\left(1+\cos\left(\frac{x-\mu}{s}\pi\right)\right) with :math:`x \in [\mu-s,\mu+s]`. Parameters ========== mu : Real number s : Real number, `s > 0` Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import RaisedCosine, density, E, variance >>> from sympy import Symbol, simplify, pprint >>> mu = Symbol("mu", real=True) >>> s = Symbol("s", positive=True) >>> z = Symbol("z") >>> X = RaisedCosine("x", mu, s) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) / /pi*(-mu + z)\ |cos|------------| + 1 | \ s / <--------------------- for And(z >= mu - s, z <= mu + s) | 2*s | \ 0 otherwise References ========== .. [1] https://en.wikipedia.org/wiki/Raised_cosine_distribution """ return rv(name, RaisedCosineDistribution, (mu, s)) #------------------------------------------------------------------------------- # Rayleigh distribution -------------------------------------------------------- class RayleighDistribution(SingleContinuousDistribution): _argnames = ('sigma',) set = Interval(0, oo) def pdf(self, x): sigma = self.sigma return x/sigma**2*exp(-x**2/(2*sigma**2)) def _characteristic_function(self, t): sigma = self.sigma return 1 - sigma*t*exp(-sigma**2*t**2/2) * sqrt(pi/2) * (erfi(sigma*t/sqrt(2)) - I) def _moment_generating_function(self, t): sigma = self.sigma return 1 + sigma*t*exp(sigma**2*t**2/2) * sqrt(pi/2) * (erf(sigma*t/sqrt(2)) + 1) def Rayleigh(name, sigma): r""" Create a continuous random variable with a Rayleigh distribution. The density of the Rayleigh distribution is given by .. math :: f(x) := \frac{x}{\sigma^2} e^{-x^2/2\sigma^2} with :math:`x > 0`. Parameters ========== sigma : Real number, `\sigma > 0` Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Rayleigh, density, E, variance >>> from sympy import Symbol, simplify >>> sigma = Symbol("sigma", positive=True) >>> z = Symbol("z") >>> X = Rayleigh("x", sigma) >>> density(X)(z) z*exp(-z**2/(2*sigma**2))/sigma**2 >>> E(X) sqrt(2)*sqrt(pi)*sigma/2 >>> variance(X) -pi*sigma**2/2 + 2*sigma**2 References ========== .. [1] https://en.wikipedia.org/wiki/Rayleigh_distribution .. [2] http://mathworld.wolfram.com/RayleighDistribution.html """ return rv(name, RayleighDistribution, (sigma, )) #------------------------------------------------------------------------------- # Shifted Gompertz distribution ------------------------------------------------ class ShiftedGompertzDistribution(SingleContinuousDistribution): _argnames = ('b', 'eta') set = Interval(0, oo) @staticmethod def check(b, eta): _value_check(b > 0, "b must be positive") _value_check(eta > 0, "eta must be positive") def pdf(self, x): b, eta = self.b, self.eta return b*exp(-b*x)*exp(-eta*exp(-b*x))*(1+eta*(1-exp(-b*x))) def ShiftedGompertz(name, b, eta): r""" Create a continuous random variable with a Shifted Gompertz distribution. The density of the Shifted Gompertz distribution is given by .. math:: f(x) := b e^{-b x} e^{-\eta \exp(-b x)} \left[1 + \eta(1 - e^(-bx)) \right] with :math: 'x \in [0, \inf)'. Parameters ========== b: Real number, 'b > 0' a scale eta: Real number, 'eta > 0' a shape Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import ShiftedGompertz, density, E, variance >>> from sympy import Symbol >>> b = Symbol("b", positive=True) >>> eta = Symbol("eta", positive=True) >>> x = Symbol("x") >>> X = ShiftedGompertz("x", b, eta) >>> density(X)(x) b*(eta*(1 - exp(-b*x)) + 1)*exp(-b*x)*exp(-eta*exp(-b*x)) References ========== .. [1] https://en.wikipedia.org/wiki/Shifted_Gompertz_distribution """ return rv(name, ShiftedGompertzDistribution, (b, eta)) #------------------------------------------------------------------------------- # StudentT distribution -------------------------------------------------------- class StudentTDistribution(SingleContinuousDistribution): _argnames = ('nu',) def pdf(self, x): nu = self.nu return 1/(sqrt(nu)*beta_fn(S(1)/2, nu/2))*(1 + x**2/nu)**(-(nu + 1)/2) def _cdf(self, x): nu = self.nu return S.Half + x*gamma((nu+1)/2)*hyper((S.Half, (nu+1)/2), (S(3)/2,), -x**2/nu)/(sqrt(pi*nu)*gamma(nu/2)) def _moment_generating_function(self, t): raise NotImplementedError('The moment generating function for the Student-T distribution is undefined.') def StudentT(name, nu): r""" Create a continuous random variable with a student's t distribution. The density of the student's t distribution is given by .. math:: f(x) := \frac{\Gamma \left(\frac{\nu+1}{2} \right)} {\sqrt{\nu\pi}\Gamma \left(\frac{\nu}{2} \right)} \left(1+\frac{x^2}{\nu} \right)^{-\frac{\nu+1}{2}} Parameters ========== nu : Real number, `\nu > 0`, the degrees of freedom Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import StudentT, density, E, variance, cdf >>> from sympy import Symbol, simplify, pprint >>> nu = Symbol("nu", positive=True) >>> z = Symbol("z") >>> X = StudentT("x", nu) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) nu 1 - -- - - 2 2 / 2\ | z | |1 + --| \ nu/ ----------------- ____ / nu\ \/ nu *B|1/2, --| \ 2 / >>> cdf(X)(z) 1/2 + z*gamma(nu/2 + 1/2)*hyper((1/2, nu/2 + 1/2), (3/2,), -z**2/nu)/(sqrt(pi)*sqrt(nu)*gamma(nu/2)) References ========== .. [1] https://en.wikipedia.org/wiki/Student_t-distribution .. [2] http://mathworld.wolfram.com/Studentst-Distribution.html """ return rv(name, StudentTDistribution, (nu, )) #------------------------------------------------------------------------------- # Trapezoidal distribution ------------------------------------------------------ class TrapezoidalDistribution(SingleContinuousDistribution): _argnames = ('a', 'b', 'c', 'd') def pdf(self, x): a, b, c, d = self.a, self.b, self.c, self.d return Piecewise( (2*(x-a) / ((b-a)*(d+c-a-b)), And(a <= x, x < b)), (2 / (d+c-a-b), And(b <= x, x < c)), (2*(d-x) / ((d-c)*(d+c-a-b)), And(c <= x, x <= d)), (S.Zero, True)) def Trapezoidal(name, a, b, c, d): r""" Create a continuous random variable with a trapezoidal distribution. The density of the trapezoidal distribution is given by .. math:: f(x) := \begin{cases} 0 & \mathrm{for\ } x < a, \\ \frac{2(x-a)}{(b-a)(d+c-a-b)} & \mathrm{for\ } a \le x < b, \\ \frac{2}{d+c-a-b} & \mathrm{for\ } b \le x < c, \\ \frac{2(d-x)}{(d-c)(d+c-a-b)} & \mathrm{for\ } c \le x < d, \\ 0 & \mathrm{for\ } d < x. \end{cases} Parameters ========== a : Real number, :math:`a < d` b : Real number, :math:`a <= b < c` c : Real number, :math:`b < c <= d` d : Real number Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Trapezoidal, density, E >>> from sympy import Symbol, pprint >>> a = Symbol("a") >>> b = Symbol("b") >>> c = Symbol("c") >>> d = Symbol("d") >>> z = Symbol("z") >>> X = Trapezoidal("x", a,b,c,d) >>> pprint(density(X)(z), use_unicode=False) / -2*a + 2*z |------------------------- for And(a <= z, b > z) |(-a + b)*(-a - b + c + d) | | 2 | -------------- for And(b <= z, c > z) < -a - b + c + d | | 2*d - 2*z |------------------------- for And(d >= z, c <= z) |(-c + d)*(-a - b + c + d) | \ 0 otherwise References ========== .. [1] https://en.wikipedia.org/wiki/Trapezoidal_distribution """ return rv(name, TrapezoidalDistribution, (a, b, c, d)) #------------------------------------------------------------------------------- # Triangular distribution ------------------------------------------------------ class TriangularDistribution(SingleContinuousDistribution): _argnames = ('a', 'b', 'c') def pdf(self, x): a, b, c = self.a, self.b, self.c return Piecewise( (2*(x - a)/((b - a)*(c - a)), And(a <= x, x < c)), (2/(b - a), Eq(x, c)), (2*(b - x)/((b - a)*(b - c)), And(c < x, x <= b)), (S.Zero, True)) def _characteristic_function(self, t): a, b, c = self.a, self.b, self.c return -2 *((b-c) * exp(I*a*t) - (b-a) * exp(I*c*t) + (c-a) * exp(I*b*t)) / ((b-a)*(c-a)*(b-c)*t**2) def _moment_generating_function(self, t): a, b, c = self.a, self.b, self.c return 2 * ((b - c) * exp(a * t) - (b - a) * exp(c * t) + (c + a) * exp(b * t)) / ( (b - a) * (c - a) * (b - c) * t ** 2) def Triangular(name, a, b, c): r""" Create a continuous random variable with a triangular distribution. The density of the triangular distribution is given by .. math:: f(x) := \begin{cases} 0 & \mathrm{for\ } x < a, \\ \frac{2(x-a)}{(b-a)(c-a)} & \mathrm{for\ } a \le x < c, \\ \frac{2}{b-a} & \mathrm{for\ } x = c, \\ \frac{2(b-x)}{(b-a)(b-c)} & \mathrm{for\ } c < x \le b, \\ 0 & \mathrm{for\ } b < x. \end{cases} Parameters ========== a : Real number, :math:`a \in \left(-\infty, \infty\right)` b : Real number, :math:`a < b` c : Real number, :math:`a \leq c \leq b` Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Triangular, density, E >>> from sympy import Symbol, pprint >>> a = Symbol("a") >>> b = Symbol("b") >>> c = Symbol("c") >>> z = Symbol("z") >>> X = Triangular("x", a,b,c) >>> pprint(density(X)(z), use_unicode=False) / -2*a + 2*z |----------------- for And(a <= z, c > z) |(-a + b)*(-a + c) | | 2 | ------ for c = z < -a + b | | 2*b - 2*z |---------------- for And(b >= z, c < z) |(-a + b)*(b - c) | \ 0 otherwise References ========== .. [1] https://en.wikipedia.org/wiki/Triangular_distribution .. [2] http://mathworld.wolfram.com/TriangularDistribution.html """ return rv(name, TriangularDistribution, (a, b, c)) #------------------------------------------------------------------------------- # Uniform distribution --------------------------------------------------------- class UniformDistribution(SingleContinuousDistribution): _argnames = ('left', 'right') def pdf(self, x): left, right = self.left, self.right return Piecewise( (S.One/(right - left), And(left <= x, x <= right)), (S.Zero, True) ) def _cdf(self, x): left, right = self.left, self.right return Piecewise( (S.Zero, x < left), ((x - left)/(right - left), x <= right), (S.One, True) ) def _characteristic_function(self, t): left, right = self.left, self.right return Piecewise(((exp(I*t*right) - exp(I*t*left)) / (I*t*(right - left)), Ne(t, 0)), (S.One, True)) def _moment_generating_function(self, t): left, right = self.left, self.right return Piecewise(((exp(t*right) - exp(t*left)) / (t * (right - left)), Ne(t, 0)), (S.One, True)) def expectation(self, expr, var, **kwargs): from sympy import Max, Min kwargs['evaluate'] = True result = SingleContinuousDistribution.expectation(self, expr, var, **kwargs) result = result.subs({Max(self.left, self.right): self.right, Min(self.left, self.right): self.left}) return result def sample(self): return random.uniform(self.left, self.right) def Uniform(name, left, right): r""" Create a continuous random variable with a uniform distribution. The density of the uniform distribution is given by .. math:: f(x) := \begin{cases} \frac{1}{b - a} & \text{for } x \in [a,b] \\ 0 & \text{otherwise} \end{cases} with :math:`x \in [a,b]`. Parameters ========== a : Real number, :math:`-\infty < a` the left boundary b : Real number, :math:`a < b < \infty` the right boundary Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Uniform, density, cdf, E, variance, skewness >>> from sympy import Symbol, simplify >>> a = Symbol("a", negative=True) >>> b = Symbol("b", positive=True) >>> z = Symbol("z") >>> X = Uniform("x", a, b) >>> density(X)(z) Piecewise((1/(-a + b), (b >= z) & (a <= z)), (0, True)) >>> cdf(X)(z) # doctest: +SKIP -a/(-a + b) + z/(-a + b) >>> simplify(E(X)) a/2 + b/2 >>> simplify(variance(X)) a**2/12 - a*b/6 + b**2/12 References ========== .. [1] https://en.wikipedia.org/wiki/Uniform_distribution_%28continuous%29 .. [2] http://mathworld.wolfram.com/UniformDistribution.html """ return rv(name, UniformDistribution, (left, right)) #------------------------------------------------------------------------------- # UniformSum distribution ------------------------------------------------------ class UniformSumDistribution(SingleContinuousDistribution): _argnames = ('n',) @property def set(self): return Interval(0, self.n) def pdf(self, x): n = self.n k = Dummy("k") return 1/factorial( n - 1)*Sum((-1)**k*binomial(n, k)*(x - k)**(n - 1), (k, 0, floor(x))) def _cdf(self, x): n = self.n k = Dummy("k") return Piecewise((S.Zero, x < 0), (1/factorial(n)*Sum((-1)**k*binomial(n, k)*(x - k)**(n), (k, 0, floor(x))), x <= n), (S.One, True)) def _characteristic_function(self, t): return ((exp(I*t) - 1) / (I*t))**self.n def _moment_generating_function(self, t): return ((exp(t) - 1) / t)**self.n def UniformSum(name, n): r""" Create a continuous random variable with an Irwin-Hall distribution. The probability distribution function depends on a single parameter `n` which is an integer. The density of the Irwin-Hall distribution is given by .. math :: f(x) := \frac{1}{(n-1)!}\sum_{k=0}^{\left\lfloor x\right\rfloor}(-1)^k \binom{n}{k}(x-k)^{n-1} Parameters ========== n : A positive Integer, `n > 0` Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import UniformSum, density, cdf >>> from sympy import Symbol, pprint >>> n = Symbol("n", integer=True) >>> z = Symbol("z") >>> X = UniformSum("x", n) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) floor(z) ___ \ ` \ k n - 1 /n\ ) (-1) *(-k + z) *| | / \k/ /__, k = 0 -------------------------------- (n - 1)! >>> cdf(X)(z) Piecewise((0, z < 0), (Sum((-1)**_k*(-_k + z)**n*binomial(n, _k), (_k, 0, floor(z)))/factorial(n), n >= z), (1, True)) Compute cdf with specific 'x' and 'n' values as follows : >>> cdf(UniformSum("x", 5), evaluate=False)(2).doit() 9/40 The argument evaluate=False prevents an attempt at evaluation of the sum for general n, before the argument 2 is passed. References ========== .. [1] https://en.wikipedia.org/wiki/Uniform_sum_distribution .. [2] http://mathworld.wolfram.com/UniformSumDistribution.html """ return rv(name, UniformSumDistribution, (n, )) #------------------------------------------------------------------------------- # VonMises distribution -------------------------------------------------------- class VonMisesDistribution(SingleContinuousDistribution): _argnames = ('mu', 'k') set = Interval(0, 2*pi) @staticmethod def check(mu, k): _value_check(k > 0, "k must be positive") def pdf(self, x): mu, k = self.mu, self.k return exp(k*cos(x-mu)) / (2*pi*besseli(0, k)) def VonMises(name, mu, k): r""" Create a Continuous Random Variable with a von Mises distribution. The density of the von Mises distribution is given by .. math:: f(x) := \frac{e^{\kappa\cos(x-\mu)}}{2\pi I_0(\kappa)} with :math:`x \in [0,2\pi]`. Parameters ========== mu : Real number, measure of location k : Real number, measure of concentration Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import VonMises, density, E, variance >>> from sympy import Symbol, simplify, pprint >>> mu = Symbol("mu") >>> k = Symbol("k", positive=True) >>> z = Symbol("z") >>> X = VonMises("x", mu, k) >>> D = density(X)(z) >>> pprint(D, use_unicode=False) k*cos(mu - z) e ------------------ 2*pi*besseli(0, k) References ========== .. [1] https://en.wikipedia.org/wiki/Von_Mises_distribution .. [2] http://mathworld.wolfram.com/vonMisesDistribution.html """ return rv(name, VonMisesDistribution, (mu, k)) #------------------------------------------------------------------------------- # Weibull distribution --------------------------------------------------------- class WeibullDistribution(SingleContinuousDistribution): _argnames = ('alpha', 'beta') set = Interval(0, oo) @staticmethod def check(alpha, beta): _value_check(alpha > 0, "Alpha must be positive") _value_check(beta > 0, "Beta must be positive") def pdf(self, x): alpha, beta = self.alpha, self.beta return beta * (x/alpha)**(beta - 1) * exp(-(x/alpha)**beta) / alpha def sample(self): return random.weibullvariate(self.alpha, self.beta) def Weibull(name, alpha, beta): r""" Create a continuous random variable with a Weibull distribution. The density of the Weibull distribution is given by .. math:: f(x) := \begin{cases} \frac{k}{\lambda}\left(\frac{x}{\lambda}\right)^{k-1} e^{-(x/\lambda)^{k}} & x\geq0\\ 0 & x<0 \end{cases} Parameters ========== lambda : Real number, :math:`\lambda > 0` a scale k : Real number, `k > 0` a shape Returns ======= A RandomSymbol. Examples ======== >>> from sympy.stats import Weibull, density, E, variance >>> from sympy import Symbol, simplify >>> l = Symbol("lambda", positive=True) >>> k = Symbol("k", positive=True) >>> z = Symbol("z") >>> X = Weibull("x", l, k) >>> density(X)(z) k*(z/lambda)**(k - 1)*exp(-(z/lambda)**k)/lambda >>> simplify(E(X)) lambda*gamma(1 + 1/k) >>> simplify(variance(X)) lambda**2*(-gamma(1 + 1/k)**2 + gamma(1 + 2/k)) References ========== .. [1] https://en.wikipedia.org/wiki/Weibull_distribution .. [2] http://mathworld.wolfram.com/WeibullDistribution.html """ return rv(name, WeibullDistribution, (alpha, beta)) #------------------------------------------------------------------------------- # Wigner semicircle distribution ----------------------------------------------- class WignerSemicircleDistribution(SingleContinuousDistribution): _argnames = ('R',) @property def set(self): return Interval(-self.R, self.R) def pdf(self, x): R = self.R return 2/(pi*R**2)*sqrt(R**2 - x**2) def _characteristic_function(self, t): return Piecewise((2 * besselj(1, self.R*t) / (self.R*t), Ne(t, 0)), (S.One, True)) def _moment_generating_function(self, t): return Piecewise((2 * besseli(1, self.R*t) / (self.R*t), Ne(t, 0)), (S.One, True)) def WignerSemicircle(name, R): r""" Create a continuous random variable with a Wigner semicircle distribution. The density of the Wigner semicircle distribution is given by .. math:: f(x) := \frac2{\pi R^2}\,\sqrt{R^2-x^2} with :math:`x \in [-R,R]`. Parameters ========== R : Real number, `R > 0`, the radius Returns ======= A `RandomSymbol`. Examples ======== >>> from sympy.stats import WignerSemicircle, density, E >>> from sympy import Symbol, simplify >>> R = Symbol("R", positive=True) >>> z = Symbol("z") >>> X = WignerSemicircle("x", R) >>> density(X)(z) 2*sqrt(R**2 - z**2)/(pi*R**2) >>> E(X) 0 References ========== .. [1] https://en.wikipedia.org/wiki/Wigner_semicircle_distribution .. [2] http://mathworld.wolfram.com/WignersSemicircleLaw.html """ return rv(name, WignerSemicircleDistribution, (R,))

81f2c15ccae4d2bee64ba2063e2bfe3a16c56fc1cc043f55d4fc3250f5aa9ae3

# -*- coding: utf-8 -*- from __future__ import print_function, division from sympy.core.basic import Basic from sympy.core.compatibility import is_sequence, as_int, string_types from sympy.core.expr import Expr from sympy.core.symbol import Symbol, symbols as _symbols from sympy.core.sympify import CantSympify from sympy.core import S from sympy.printing.defaults import DefaultPrinting from sympy.utilities import public from sympy.utilities.iterables import flatten from sympy.utilities.magic import pollute from sympy import sign @public def free_group(symbols): """Construct a free group returning ``(FreeGroup, (f_0, f_1, ..., f_(n-1))``. Parameters ---------- symbols : str, Symbol/Expr or sequence of str, Symbol/Expr (may be empty) Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> F, x, y, z = free_group("x, y, z") >>> F <free group on the generators (x, y, z)> >>> x**2*y**-1 x**2*y**-1 >>> type(_) <class 'sympy.combinatorics.free_groups.FreeGroupElement'> """ _free_group = FreeGroup(symbols) return (_free_group,) + tuple(_free_group.generators) @public def xfree_group(symbols): """Construct a free group returning ``(FreeGroup, (f_0, f_1, ..., f_(n-1)))``. Parameters ---------- symbols : str, Symbol/Expr or sequence of str, Symbol/Expr (may be empty) Examples ======== >>> from sympy.combinatorics.free_groups import xfree_group >>> F, (x, y, z) = xfree_group("x, y, z") >>> F <free group on the generators (x, y, z)> >>> y**2*x**-2*z**-1 y**2*x**-2*z**-1 >>> type(_) <class 'sympy.combinatorics.free_groups.FreeGroupElement'> """ _free_group = FreeGroup(symbols) return (_free_group, _free_group.generators) @public def vfree_group(symbols): """Construct a free group and inject ``f_0, f_1, ..., f_(n-1)`` as symbols into the global namespace. Parameters ---------- symbols : str, Symbol/Expr or sequence of str, Symbol/Expr (may be empty) Examples ======== >>> from sympy.combinatorics.free_groups import vfree_group >>> vfree_group("x, y, z") <free group on the generators (x, y, z)> >>> x**2*y**-2*z x**2*y**-2*z >>> type(_) <class 'sympy.combinatorics.free_groups.FreeGroupElement'> """ _free_group = FreeGroup(symbols) pollute([sym.name for sym in _free_group.symbols], _free_group.generators) return _free_group def _parse_symbols(symbols): if not symbols: return tuple() if isinstance(symbols, string_types): return _symbols(symbols, seq=True) elif isinstance(symbols, Expr or FreeGroupElement): return (symbols,) elif is_sequence(symbols): if all(isinstance(s, string_types) for s in symbols): return _symbols(symbols) elif all(isinstance(s, Expr) for s in symbols): return symbols raise ValueError("The type of `symbols` must be one of the following: " "a str, Symbol/Expr or a sequence of " "one of these types") ############################################################################## # FREE GROUP # ############################################################################## _free_group_cache = {} class FreeGroup(DefaultPrinting): """ Free group with finite or infinite number of generators. Its input API is that of a str, Symbol/Expr or a sequence of one of these types (which may be empty) References ========== [1] http://www.gap-system.org/Manuals/doc/ref/chap37.html [2] https://en.wikipedia.org/wiki/Free_group See Also ======== sympy.polys.rings.PolyRing """ is_associative = True is_group = True is_FreeGroup = True is_PermutationGroup = False relators = tuple() def __new__(cls, symbols): symbols = tuple(_parse_symbols(symbols)) rank = len(symbols) _hash = hash((cls.__name__, symbols, rank)) obj = _free_group_cache.get(_hash) if obj is None: obj = object.__new__(cls) obj._hash = _hash obj._rank = rank # dtype method is used to create new instances of FreeGroupElement obj.dtype = type("FreeGroupElement", (FreeGroupElement,), {"group": obj}) obj.symbols = symbols obj.generators = obj._generators() obj._gens_set = set(obj.generators) for symbol, generator in zip(obj.symbols, obj.generators): if isinstance(symbol, Symbol): name = symbol.name if hasattr(obj, name): setattr(obj, name, generator) _free_group_cache[_hash] = obj return obj def _generators(group): """Returns the generators of the FreeGroup. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> F, x, y, z = free_group("x, y, z") >>> F.generators (x, y, z) """ gens = [] for sym in group.symbols: elm = ((sym, 1),) gens.append(group.dtype(elm)) return tuple(gens) def clone(self, symbols=None): return self.__class__(symbols or self.symbols) def __contains__(self, i): """Return True if ``i`` is contained in FreeGroup.""" if not isinstance(i, FreeGroupElement): return False group = i.group return self == group def __hash__(self): return self._hash def __len__(self): return self.rank def __str__(self): if self.rank > 30: str_form = "<free group with %s generators>" % self.rank else: str_form = "<free group on the generators " gens = self.generators str_form += str(gens) + ">" return str_form __repr__ = __str__ def __getitem__(self, index): symbols = self.symbols[index] return self.clone(symbols=symbols) def __eq__(self, other): """No ``FreeGroup`` is equal to any "other" ``FreeGroup``. """ return self is other def index(self, gen): """Return the index of the generator `gen` from ``(f_0, ..., f_(n-1))``. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> F, x, y = free_group("x, y") >>> F.index(y) 1 >>> F.index(x) 0 """ if isinstance(gen, self.dtype): return self.generators.index(gen) else: raise ValueError("expected a generator of Free Group %s, got %s" % (self, gen)) def order(self): """Return the order of the free group. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> F, x, y = free_group("x, y") >>> F.order() oo >>> free_group("")[0].order() 1 """ if self.rank == 0: return 1 else: return S.Infinity @property def elements(self): """ Return the elements of the free group. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> (z,) = free_group("") >>> z.elements {<identity>} """ if self.rank == 0: # A set containing Identity element of `FreeGroup` self is returned return {self.identity} else: raise ValueError("Group contains infinitely many elements" ", hence can't be represented") @property def rank(self): r""" In group theory, the `rank` of a group `G`, denoted `G.rank`, can refer to the smallest cardinality of a generating set for G, that is \operatorname{rank}(G)=\min\{ |X|: X\subseteq G, \left\langle X\right\rangle =G\}. """ return self._rank @property def is_abelian(self): """Returns if the group is Abelian. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, x, y, z = free_group("x y z") >>> f.is_abelian False """ if self.rank == 0 or self.rank == 1: return True else: return False @property def identity(self): """Returns the identity element of free group.""" return self.dtype() def contains(self, g): """Tests if Free Group element ``g`` belong to self, ``G``. In mathematical terms any linear combination of generators of a Free Group is contained in it. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, x, y, z = free_group("x y z") >>> f.contains(x**3*y**2) True """ if not isinstance(g, FreeGroupElement): return False elif self != g.group: return False else: return True def center(self): """Returns the center of the free group `self`.""" return {self.identity} ############################################################################ # FreeGroupElement # ############################################################################ class FreeGroupElement(CantSympify, DefaultPrinting, tuple): """Used to create elements of FreeGroup. It can not be used directly to create a free group element. It is called by the `dtype` method of the `FreeGroup` class. """ is_assoc_word = True def new(self, init): return self.__class__(init) _hash = None def __hash__(self): _hash = self._hash if _hash is None: self._hash = _hash = hash((self.group, frozenset(tuple(self)))) return _hash def copy(self): return self.new(self) @property def is_identity(self): if self.array_form == tuple(): return True else: return False @property def array_form(self): """ SymPy provides two different internal kinds of representation of associative words. The first one is called the `array_form` which is a tuple containing `tuples` as its elements, where the size of each tuple is two. At the first position the tuple contains the `symbol-generator`, while at the second position of tuple contains the exponent of that generator at the position. Since elements (i.e. words) don't commute, the indexing of tuple makes that property to stay. The structure in ``array_form`` of ``FreeGroupElement`` is of form: ``( ( symbol_of_gen , exponent ), ( , ), ... ( , ) )`` Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, x, y, z = free_group("x y z") >>> (x*z).array_form ((x, 1), (z, 1)) >>> (x**2*z*y*x**2).array_form ((x, 2), (z, 1), (y, 1), (x, 2)) See Also ======== letter_repr """ return tuple(self) @property def letter_form(self): """ The letter representation of a ``FreeGroupElement`` is a tuple of generator symbols, with each entry corresponding to a group generator. Inverses of the generators are represented by negative generator symbols. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, a, b, c, d = free_group("a b c d") >>> (a**3).letter_form (a, a, a) >>> (a**2*d**-2*a*b**-4).letter_form (a, a, -d, -d, a, -b, -b, -b, -b) >>> (a**-2*b**3*d).letter_form (-a, -a, b, b, b, d) See Also ======== array_form """ return tuple(flatten([(i,)*j if j > 0 else (-i,)*(-j) for i, j in self.array_form])) def __getitem__(self, i): group = self.group r = self.letter_form[i] if r.is_Symbol: return group.dtype(((r, 1),)) else: return group.dtype(((-r, -1),)) def index(self, gen): if len(gen) != 1: raise ValueError() return (self.letter_form).index(gen.letter_form[0]) @property def letter_form_elm(self): """ """ group = self.group r = self.letter_form return [group.dtype(((elm,1),)) if elm.is_Symbol \ else group.dtype(((-elm,-1),)) for elm in r] @property def ext_rep(self): """This is called the External Representation of ``FreeGroupElement`` """ return tuple(flatten(self.array_form)) def __contains__(self, gen): return gen.array_form[0][0] in tuple([r[0] for r in self.array_form]) def __str__(self): if self.is_identity: return "<identity>" symbols = self.group.symbols str_form = "" array_form = self.array_form for i in range(len(array_form)): if i == len(array_form) - 1: if array_form[i][1] == 1: str_form += str(array_form[i][0]) else: str_form += str(array_form[i][0]) + \ "**" + str(array_form[i][1]) else: if array_form[i][1] == 1: str_form += str(array_form[i][0]) + "*" else: str_form += str(array_form[i][0]) + \ "**" + str(array_form[i][1]) + "*" return str_form __repr__ = __str__ def __pow__(self, n): n = as_int(n) group = self.group if n == 0: return group.identity if n < 0: n = -n return (self.inverse())**n result = self for i in range(n - 1): result = result*self # this method can be improved instead of just returning the # multiplication of elements return result def __mul__(self, other): """Returns the product of elements belonging to the same ``FreeGroup``. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, x, y, z = free_group("x y z") >>> x*y**2*y**-4 x*y**-2 >>> z*y**-2 z*y**-2 >>> x**2*y*y**-1*x**-2 <identity> """ group = self.group if not isinstance(other, group.dtype): raise TypeError("only FreeGroup elements of same FreeGroup can " "be multiplied") if self.is_identity: return other if other.is_identity: return self r = list(self.array_form + other.array_form) zero_mul_simp(r, len(self.array_form) - 1) return group.dtype(tuple(r)) def __div__(self, other): group = self.group if not isinstance(other, group.dtype): raise TypeError("only FreeGroup elements of same FreeGroup can " "be multiplied") return self*(other.inverse()) def __rdiv__(self, other): group = self.group if not isinstance(other, group.dtype): raise TypeError("only FreeGroup elements of same FreeGroup can " "be multiplied") return other*(self.inverse()) __truediv__ = __div__ __rtruediv__ = __rdiv__ def __add__(self, other): return NotImplemented def inverse(self): """ Returns the inverse of a ``FreeGroupElement`` element Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, x, y, z = free_group("x y z") >>> x.inverse() x**-1 >>> (x*y).inverse() y**-1*x**-1 """ group = self.group r = tuple([(i, -j) for i, j in self.array_form[::-1]]) return group.dtype(r) def order(self): """Find the order of a ``FreeGroupElement``. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, x, y = free_group("x y") >>> (x**2*y*y**-1*x**-2).order() 1 """ if self.is_identity: return 1 else: return S.Infinity def commutator(self, other): """ Return the commutator of `self` and `x`: ``~x*~self*x*self`` """ group = self.group if not isinstance(other, group.dtype): raise ValueError("commutator of only FreeGroupElement of the same " "FreeGroup exists") else: return self.inverse()*other.inverse()*self*other def eliminate_words(self, words, _all=False, inverse=True): ''' Replace each subword from the dictionary `words` by words[subword]. If words is a list, replace the words by the identity. ''' again = True new = self if isinstance(words, dict): while again: again = False for sub in words: prev = new new = new.eliminate_word(sub, words[sub], _all=_all, inverse=inverse) if new != prev: again = True else: while again: again = False for sub in words: prev = new new = new.eliminate_word(sub, _all=_all, inverse=inverse) if new != prev: again = True return new def eliminate_word(self, gen, by=None, _all=False, inverse=True): """ For an associative word `self`, a subword `gen`, and an associative word `by` (identity by default), return the associative word obtained by replacing each occurrence of `gen` in `self` by `by`. If `_all = True`, the occurrences of `gen` that may appear after the first substitution will also be replaced and so on until no occurrences are found. This might not always terminate (e.g. `(x).eliminate_word(x, x**2, _all=True)`). Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, x, y = free_group("x y") >>> w = x**5*y*x**2*y**-4*x >>> w.eliminate_word( x, x**2 ) x**10*y*x**4*y**-4*x**2 >>> w.eliminate_word( x, y**-1 ) y**-11 >>> w.eliminate_word(x**5) y*x**2*y**-4*x >>> w.eliminate_word(x*y, y) x**4*y*x**2*y**-4*x See Also ======== substituted_word """ if by == None: by = self.group.identity if self.is_independent(gen) or gen == by: return self if gen == self: return by if gen**-1 == by: _all = False word = self l = len(gen) try: i = word.subword_index(gen) k = 1 except ValueError: if not inverse: return word try: i = word.subword_index(gen**-1) k = -1 except ValueError: return word word = word.subword(0, i)*by**k*word.subword(i+l, len(word)).eliminate_word(gen, by) if _all: return word.eliminate_word(gen, by, _all=True, inverse=inverse) else: return word def __len__(self): """ For an associative word `self`, returns the number of letters in it. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, a, b = free_group("a b") >>> w = a**5*b*a**2*b**-4*a >>> len(w) 13 >>> len(a**17) 17 >>> len(w**0) 0 """ return sum(abs(j) for (i, j) in self) def __eq__(self, other): """ Two associative words are equal if they are words over the same alphabet and if they are sequences of the same letters. This is equivalent to saying that the external representations of the words are equal. There is no "universal" empty word, every alphabet has its own empty word. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, swapnil0, swapnil1 = free_group("swapnil0 swapnil1") >>> f <free group on the generators (swapnil0, swapnil1)> >>> g, swap0, swap1 = free_group("swap0 swap1") >>> g <free group on the generators (swap0, swap1)> >>> swapnil0 == swapnil1 False >>> swapnil0*swapnil1 == swapnil1/swapnil1*swapnil0*swapnil1 True >>> swapnil0*swapnil1 == swapnil1*swapnil0 False >>> swapnil1**0 == swap0**0 False """ group = self.group if not isinstance(other, group.dtype): return False return tuple.__eq__(self, other) def __lt__(self, other): """ The ordering of associative words is defined by length and lexicography (this ordering is called short-lex ordering), that is, shorter words are smaller than longer words, and words of the same length are compared w.r.t. the lexicographical ordering induced by the ordering of generators. Generators are sorted according to the order in which they were created. If the generators are invertible then each generator `g` is larger than its inverse `g^{-1}`, and `g^{-1}` is larger than every generator that is smaller than `g`. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, a, b = free_group("a b") >>> b < a False >>> a < a.inverse() False """ group = self.group if not isinstance(other, group.dtype): raise TypeError("only FreeGroup elements of same FreeGroup can " "be compared") l = len(self) m = len(other) # implement lenlex order if l < m: return True elif l > m: return False for i in range(l): a = self[i].array_form[0] b = other[i].array_form[0] p = group.symbols.index(a[0]) q = group.symbols.index(b[0]) if p < q: return True elif p > q: return False elif a[1] < b[1]: return True elif a[1] > b[1]: return False return False def __le__(self, other): return (self == other or self < other) def __gt__(self, other): """ Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, x, y, z = free_group("x y z") >>> y**2 > x**2 True >>> y*z > z*y False >>> x > x.inverse() True """ group = self.group if not isinstance(other, group.dtype): raise TypeError("only FreeGroup elements of same FreeGroup can " "be compared") return not self <= other def __ge__(self, other): return not self < other def exponent_sum(self, gen): """ For an associative word `self` and a generator or inverse of generator `gen`, ``exponent_sum`` returns the number of times `gen` appears in `self` minus the number of times its inverse appears in `self`. If neither `gen` nor its inverse occur in `self` then 0 is returned. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> F, x, y = free_group("x, y") >>> w = x**2*y**3 >>> w.exponent_sum(x) 2 >>> w.exponent_sum(x**-1) -2 >>> w = x**2*y**4*x**-3 >>> w.exponent_sum(x) -1 See Also ======== generator_count """ if len(gen) != 1: raise ValueError("gen must be a generator or inverse of a generator") s = gen.array_form[0] return s[1]*sum([i[1] for i in self.array_form if i[0] == s[0]]) def generator_count(self, gen): """ For an associative word `self` and a generator `gen`, ``generator_count`` returns the multiplicity of generator `gen` in `self`. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> F, x, y = free_group("x, y") >>> w = x**2*y**3 >>> w.generator_count(x) 2 >>> w = x**2*y**4*x**-3 >>> w.generator_count(x) 5 See Also ======== exponent_sum """ if len(gen) != 1 or gen.array_form[0][1] < 0: raise ValueError("gen must be a generator") s = gen.array_form[0] return s[1]*sum([abs(i[1]) for i in self.array_form if i[0] == s[0]]) def subword(self, from_i, to_j, strict=True): """ For an associative word `self` and two positive integers `from_i` and `to_j`, `subword` returns the subword of `self` that begins at position `from_i` and ends at `to_j - 1`, indexing is done with origin 0. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, a, b = free_group("a b") >>> w = a**5*b*a**2*b**-4*a >>> w.subword(2, 6) a**3*b """ group = self.group if not strict: from_i = max(from_i, 0) to_j = min(len(self), to_j) if from_i < 0 or to_j > len(self): raise ValueError("`from_i`, `to_j` must be positive and no greater than " "the length of associative word") if to_j <= from_i: return group.identity else: letter_form = self.letter_form[from_i: to_j] array_form = letter_form_to_array_form(letter_form, group) return group.dtype(array_form) def subword_index(self, word, start = 0): ''' Find the index of `word` in `self`. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, a, b = free_group("a b") >>> w = a**2*b*a*b**3 >>> w.subword_index(a*b*a*b) 1 ''' l = len(word) self_lf = self.letter_form word_lf = word.letter_form index = None for i in range(start,len(self_lf)-l+1): if self_lf[i:i+l] == word_lf: index = i break if index is not None: return index else: raise ValueError("The given word is not a subword of self") def is_dependent(self, word): """ Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> F, x, y = free_group("x, y") >>> (x**4*y**-3).is_dependent(x**4*y**-2) True >>> (x**2*y**-1).is_dependent(x*y) False >>> (x*y**2*x*y**2).is_dependent(x*y**2) True >>> (x**12).is_dependent(x**-4) True See Also ======== is_independent """ try: return self.subword_index(word) != None except ValueError: pass try: return self.subword_index(word**-1) != None except ValueError: return False def is_independent(self, word): """ See Also ======== is_dependent """ return not self.is_dependent(word) def contains_generators(self): """ Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> F, x, y, z = free_group("x, y, z") >>> (x**2*y**-1).contains_generators() {x, y} >>> (x**3*z).contains_generators() {x, z} """ group = self.group gens = set() for syllable in self.array_form: gens.add(group.dtype(((syllable[0], 1),))) return set(gens) def cyclic_subword(self, from_i, to_j): group = self.group l = len(self) letter_form = self.letter_form period1 = int(from_i/l) if from_i >= l: from_i -= l*period1 to_j -= l*period1 diff = to_j - from_i word = letter_form[from_i: to_j] period2 = int(to_j/l) - 1 word += letter_form*period2 + letter_form[:diff-l+from_i-l*period2] word = letter_form_to_array_form(word, group) return group.dtype(word) def cyclic_conjugates(self): """Returns a words which are cyclic to the word `self`. References ========== http://planetmath.org/cyclicpermutation Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> F, x, y = free_group("x, y") >>> w = x*y*x*y*x >>> w.cyclic_conjugates() {x*y*x**2*y, x**2*y*x*y, y*x*y*x**2, y*x**2*y*x, x*y*x*y*x} >>> s = x*y*x**2*y*x >>> s.cyclic_conjugates() {x**2*y*x**2*y, y*x**2*y*x**2, x*y*x**2*y*x} """ return {self.cyclic_subword(i, i+len(self)) for i in range(len(self))} def is_cyclic_conjugate(self, w): """ Checks whether words ``self``, ``w`` are cyclic conjugates. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> F, x, y = free_group("x, y") >>> w1 = x**2*y**5 >>> w2 = x*y**5*x >>> w1.is_cyclic_conjugate(w2) True >>> w3 = x**-1*y**5*x**-1 >>> w3.is_cyclic_conjugate(w2) False """ l1 = len(self) l2 = len(w) if l1 != l2: return False w1 = self.identity_cyclic_reduction() w2 = w.identity_cyclic_reduction() letter1 = w1.letter_form letter2 = w2.letter_form str1 = ' '.join(map(str, letter1)) str2 = ' '.join(map(str, letter2)) if len(str1) != len(str2): return False return str1 in str2 + ' ' + str2 def number_syllables(self): """Returns the number of syllables of the associative word `self`. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, swapnil0, swapnil1 = free_group("swapnil0 swapnil1") >>> (swapnil1**3*swapnil0*swapnil1**-1).number_syllables() 3 """ return len(self.array_form) def exponent_syllable(self, i): """ Returns the exponent of the `i`-th syllable of the associative word `self`. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, a, b = free_group("a b") >>> w = a**5*b*a**2*b**-4*a >>> w.exponent_syllable( 2 ) 2 """ return self.array_form[i][1] def generator_syllable(self, i): """ Returns the symbol of the generator that is involved in the i-th syllable of the associative word `self`. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, a, b = free_group("a b") >>> w = a**5*b*a**2*b**-4*a >>> w.generator_syllable( 3 ) b """ return self.array_form[i][0] def sub_syllables(self, from_i, to_j): """ `sub_syllables` returns the subword of the associative word `self` that consists of syllables from positions `from_to` to `to_j`, where `from_to` and `to_j` must be positive integers and indexing is done with origin 0. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> f, a, b = free_group("a, b") >>> w = a**5*b*a**2*b**-4*a >>> w.sub_syllables(1, 2) b >>> w.sub_syllables(3, 3) <identity> """ if not isinstance(from_i, int) or not isinstance(to_j, int): raise ValueError("both arguments should be integers") group = self.group if to_j <= from_i: return group.identity else: r = tuple(self.array_form[from_i: to_j]) return group.dtype(r) def substituted_word(self, from_i, to_j, by): """ Returns the associative word obtained by replacing the subword of `self` that begins at position `from_i` and ends at position `to_j - 1` by the associative word `by`. `from_i` and `to_j` must be positive integers, indexing is done with origin 0. In other words, `w.substituted_word(w, from_i, to_j, by)` is the product of the three words: `w.subword(0, from_i)`, `by`, and `w.subword(to_j len(w))`. See Also ======== eliminate_word """ lw = len(self) if from_i >= to_j or from_i > lw or to_j > lw: raise ValueError("values should be within bounds") # otherwise there are four possibilities # first if from=1 and to=lw then if from_i == 0 and to_j == lw: return by elif from_i == 0: # second if from_i=1 (and to_j < lw) then return by*self.subword(to_j, lw) elif to_j == lw: # third if to_j=1 (and from_i > 1) then return self.subword(0, from_i)*by else: # finally return self.subword(0, from_i)*by*self.subword(to_j, lw) def is_cyclically_reduced(self): r"""Returns whether the word is cyclically reduced or not. A word is cyclically reduced if by forming the cycle of the word, the word is not reduced, i.e a word w = `a_1 ... a_n` is called cyclically reduced if `a_1 \ne a_n^{−1}`. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> F, x, y = free_group("x, y") >>> (x**2*y**-1*x**-1).is_cyclically_reduced() False >>> (y*x**2*y**2).is_cyclically_reduced() True """ if not self: return True return self[0] != self[-1]**-1 def identity_cyclic_reduction(self): """Return a unique cyclically reduced version of the word. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> F, x, y = free_group("x, y") >>> (x**2*y**2*x**-1).identity_cyclic_reduction() x*y**2 >>> (x**-3*y**-1*x**5).identity_cyclic_reduction() x**2*y**-1 References ========== http://planetmath.org/cyclicallyreduced """ word = self.copy() group = self.group while not word.is_cyclically_reduced(): exp1 = word.exponent_syllable(0) exp2 = word.exponent_syllable(-1) r = exp1 + exp2 if r == 0: rep = word.array_form[1: word.number_syllables() - 1] else: rep = ((word.generator_syllable(0), exp1 + exp2),) + \ word.array_form[1: word.number_syllables() - 1] word = group.dtype(rep) return word def cyclic_reduction(self, removed=False): """Return a cyclically reduced version of the word. Unlike `identity_cyclic_reduction`, this will not cyclically permute the reduced word - just remove the "unreduced" bits on either side of it. Compare the examples with those of `identity_cyclic_reduction`. When `removed` is `True`, return a tuple `(word, r)` where self `r` is such that before the reduction the word was either `r*word*r**-1`. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> F, x, y = free_group("x, y") >>> (x**2*y**2*x**-1).cyclic_reduction() x*y**2 >>> (x**-3*y**-1*x**5).cyclic_reduction() y**-1*x**2 >>> (x**-3*y**-1*x**5).cyclic_reduction(removed=True) (y**-1*x**2, x**-3) """ word = self.copy() group = self.group g = self.group.identity while not word.is_cyclically_reduced(): exp1 = abs(word.exponent_syllable(0)) exp2 = abs(word.exponent_syllable(-1)) exp = min(exp1, exp2) start = word[0]**abs(exp) end = word[-1]**abs(exp) word = start**-1*word*end**-1 g = g*start if removed: return word, g return word def power_of(self, other): ''' Check if `self == other**n` for some integer n. Examples ======== >>> from sympy.combinatorics.free_groups import free_group >>> F, x, y = free_group("x, y") >>> ((x*y)**2).power_of(x*y) True >>> (x**-3*y**-2*x**3).power_of(x**-3*y*x**3) True ''' if self.is_identity: return True l = len(other) if l == 1: # self has to be a power of one generator gens = self.contains_generators() s = other in gens or other**-1 in gens return len(gens) == 1 and s # if self is not cyclically reduced and it is a power of other, # other isn't cyclically reduced and the parts removed during # their reduction must be equal reduced, r1 = self.cyclic_reduction(removed=True) if not r1.is_identity: other, r2 = other.cyclic_reduction(removed=True) if r1 == r2: return reduced.power_of(other) return False if len(self) < l or len(self) % l: return False prefix = self.subword(0, l) if prefix == other or prefix**-1 == other: rest = self.subword(l, len(self)) return rest.power_of(other) return False def letter_form_to_array_form(array_form, group): """ This method converts a list given with possible repetitions of elements in it. It returns a new list such that repetitions of consecutive elements is removed and replace with a tuple element of size two such that the first index contains `value` and the second index contains the number of consecutive repetitions of `value`. """ a = list(array_form[:]) new_array = [] n = 1 symbols = group.symbols for i in range(len(a)): if i == len(a) - 1: if a[i] == a[i - 1]: if (-a[i]) in symbols: new_array.append((-a[i], -n)) else: new_array.append((a[i], n)) else: if (-a[i]) in symbols: new_array.append((-a[i], -1)) else: new_array.append((a[i], 1)) return new_array elif a[i] == a[i + 1]: n += 1 else: if (-a[i]) in symbols: new_array.append((-a[i], -n)) else: new_array.append((a[i], n)) n = 1 def zero_mul_simp(l, index): """Used to combine two reduced words.""" while index >=0 and index < len(l) - 1 and l[index][0] == l[index + 1][0]: exp = l[index][1] + l[index + 1][1] base = l[index][0] l[index] = (base, exp) del l[index + 1] if l[index][1] == 0: del l[index] index -= 1

53fbe4d439dffb6950e8094e0d5095d333a54de40db58247d20f932a006be02c

from __future__ import print_function, division from sympy.core.compatibility import range from sympy.core.mul import Mul from sympy.core.singleton import S from sympy.concrete.expr_with_intlimits import ExprWithIntLimits from sympy.core.exprtools import factor_terms from sympy.functions.elementary.exponential import exp, log from sympy.polys import quo, roots from sympy.simplify import powsimp class Product(ExprWithIntLimits): r"""Represents unevaluated products. ``Product`` represents a finite or infinite product, with the first argument being the general form of terms in the series, and the second argument being ``(dummy_variable, start, end)``, with ``dummy_variable`` taking all integer values from ``start`` through ``end``. In accordance with long-standing mathematical convention, the end term is included in the product. Finite products =============== For finite products (and products with symbolic limits assumed to be finite) we follow the analogue of the summation convention described by Karr [1], especially definition 3 of section 1.4. The product: .. math:: \prod_{m \leq i < n} f(i) has *the obvious meaning* for `m < n`, namely: .. math:: \prod_{m \leq i < n} f(i) = f(m) f(m+1) \cdot \ldots \cdot f(n-2) f(n-1) with the upper limit value `f(n)` excluded. The product over an empty set is one if and only if `m = n`: .. math:: \prod_{m \leq i < n} f(i) = 1 \quad \mathrm{for} \quad m = n Finally, for all other products over empty sets we assume the following definition: .. math:: \prod_{m \leq i < n} f(i) = \frac{1}{\prod_{n \leq i < m} f(i)} \quad \mathrm{for} \quad m > n It is important to note that above we define all products with the upper limit being exclusive. This is in contrast to the usual mathematical notation, but does not affect the product convention. Indeed we have: .. math:: \prod_{m \leq i < n} f(i) = \prod_{i = m}^{n - 1} f(i) where the difference in notation is intentional to emphasize the meaning, with limits typeset on the top being inclusive. Examples ======== >>> from sympy.abc import a, b, i, k, m, n, x >>> from sympy import Product, factorial, oo >>> Product(k, (k, 1, m)) Product(k, (k, 1, m)) >>> Product(k, (k, 1, m)).doit() factorial(m) >>> Product(k**2,(k, 1, m)) Product(k**2, (k, 1, m)) >>> Product(k**2,(k, 1, m)).doit() factorial(m)**2 Wallis' product for pi: >>> W = Product(2*i/(2*i-1) * 2*i/(2*i+1), (i, 1, oo)) >>> W Product(4*i**2/((2*i - 1)*(2*i + 1)), (i, 1, oo)) Direct computation currently fails: >>> W.doit() Product(4*i**2/((2*i - 1)*(2*i + 1)), (i, 1, oo)) But we can approach the infinite product by a limit of finite products: >>> from sympy import limit >>> W2 = Product(2*i/(2*i-1)*2*i/(2*i+1), (i, 1, n)) >>> W2 Product(4*i**2/((2*i - 1)*(2*i + 1)), (i, 1, n)) >>> W2e = W2.doit() >>> W2e 2**(-2*n)*4**n*factorial(n)**2/(RisingFactorial(1/2, n)*RisingFactorial(3/2, n)) >>> limit(W2e, n, oo) pi/2 By the same formula we can compute sin(pi/2): >>> from sympy import pi, gamma, simplify >>> P = pi * x * Product(1 - x**2/k**2, (k, 1, n)) >>> P = P.subs(x, pi/2) >>> P pi**2*Product(1 - pi**2/(4*k**2), (k, 1, n))/2 >>> Pe = P.doit() >>> Pe pi**2*RisingFactorial(1 + pi/2, n)*RisingFactorial(-pi/2 + 1, n)/(2*factorial(n)**2) >>> Pe = Pe.rewrite(gamma) >>> Pe pi**2*gamma(n + 1 + pi/2)*gamma(n - pi/2 + 1)/(2*gamma(1 + pi/2)*gamma(-pi/2 + 1)*gamma(n + 1)**2) >>> Pe = simplify(Pe) >>> Pe sin(pi**2/2)*gamma(n + 1 + pi/2)*gamma(n - pi/2 + 1)/gamma(n + 1)**2 >>> limit(Pe, n, oo) sin(pi**2/2) Products with the lower limit being larger than the upper one: >>> Product(1/i, (i, 6, 1)).doit() 120 >>> Product(i, (i, 2, 5)).doit() 120 The empty product: >>> Product(i, (i, n, n-1)).doit() 1 An example showing that the symbolic result of a product is still valid for seemingly nonsensical values of the limits. Then the Karr convention allows us to give a perfectly valid interpretation to those products by interchanging the limits according to the above rules: >>> P = Product(2, (i, 10, n)).doit() >>> P 2**(n - 9) >>> P.subs(n, 5) 1/16 >>> Product(2, (i, 10, 5)).doit() 1/16 >>> 1/Product(2, (i, 6, 9)).doit() 1/16 An explicit example of the Karr summation convention applied to products: >>> P1 = Product(x, (i, a, b)).doit() >>> P1 x**(-a + b + 1) >>> P2 = Product(x, (i, b+1, a-1)).doit() >>> P2 x**(a - b - 1) >>> simplify(P1 * P2) 1 And another one: >>> P1 = Product(i, (i, b, a)).doit() >>> P1 RisingFactorial(b, a - b + 1) >>> P2 = Product(i, (i, a+1, b-1)).doit() >>> P2 RisingFactorial(a + 1, -a + b - 1) >>> P1 * P2 RisingFactorial(b, a - b + 1)*RisingFactorial(a + 1, -a + b - 1) >>> simplify(P1 * P2) 1 See Also ======== Sum, summation product References ========== .. [1] Michael Karr, "Summation in Finite Terms", Journal of the ACM, Volume 28 Issue 2, April 1981, Pages 305-350 http://dl.acm.org/citation.cfm?doid=322248.322255 .. [2] https://en.wikipedia.org/wiki/Multiplication#Capital_Pi_notation .. [3] https://en.wikipedia.org/wiki/Empty_product """ __slots__ = ['is_commutative'] def __new__(cls, function, *symbols, **assumptions): obj = ExprWithIntLimits.__new__(cls, function, *symbols, **assumptions) return obj def _eval_rewrite_as_Sum(self, *args, **kwargs): from sympy.concrete.summations import Sum return exp(Sum(log(self.function), *self.limits)) @property def term(self): return self._args[0] function = term def _eval_is_zero(self): # a Product is zero only if its term is zero. return self.term.is_zero def doit(self, **hints): f = self.function for index, limit in enumerate(self.limits): i, a, b = limit dif = b - a if dif.is_Integer and dif < 0: a, b = b + 1, a - 1 f = 1 / f g = self._eval_product(f, (i, a, b)) if g in (None, S.NaN): return self.func(powsimp(f), *self.limits[index:]) else: f = g if hints.get('deep', True): return f.doit(**hints) else: return powsimp(f) def _eval_adjoint(self): if self.is_commutative: return self.func(self.function.adjoint(), *self.limits) return None def _eval_conjugate(self): return self.func(self.function.conjugate(), *self.limits) def _eval_product(self, term, limits): from sympy.concrete.delta import deltaproduct, _has_simple_delta from sympy.concrete.summations import summation from sympy.functions import KroneckerDelta, RisingFactorial (k, a, n) = limits if k not in term.free_symbols: if (term - 1).is_zero: return S.One return term**(n - a + 1) if a == n: return term.subs(k, a) if term.has(KroneckerDelta) and _has_simple_delta(term, limits[0]): return deltaproduct(term, limits) dif = n - a if dif.is_Integer: return Mul(*[term.subs(k, a + i) for i in range(dif + 1)]) elif term.is_polynomial(k): poly = term.as_poly(k) A = B = Q = S.One all_roots = roots(poly) M = 0 for r, m in all_roots.items(): M += m A *= RisingFactorial(a - r, n - a + 1)**m Q *= (n - r)**m if M < poly.degree(): arg = quo(poly, Q.as_poly(k)) B = self.func(arg, (k, a, n)).doit() return poly.LC()**(n - a + 1) * A * B elif term.is_Add: factored = factor_terms(term, fraction=True) if factored.is_Mul: return self._eval_product(factored, (k, a, n)) elif term.is_Mul: exclude, include = [], [] for t in term.args: p = self._eval_product(t, (k, a, n)) if p is not None: exclude.append(p) else: include.append(t) if not exclude: return None else: arg = term._new_rawargs(*include) A = Mul(*exclude) B = self.func(arg, (k, a, n)).doit() return A * B elif term.is_Pow: if not term.base.has(k): s = summation(term.exp, (k, a, n)) return term.base**s elif not term.exp.has(k): p = self._eval_product(term.base, (k, a, n)) if p is not None: return p**term.exp elif isinstance(term, Product): evaluated = term.doit() f = self._eval_product(evaluated, limits) if f is None: return self.func(evaluated, limits) else: return f def _eval_simplify(self, ratio, measure, rational, inverse): from sympy.simplify.simplify import product_simplify return product_simplify(self) def _eval_transpose(self): if self.is_commutative: return self.func(self.function.transpose(), *self.limits) return None def is_convergent(self): r""" See docs of Sum.is_convergent() for explanation of convergence in SymPy. The infinite product: .. math:: \prod_{1 \leq i < \infty} f(i) is defined by the sequence of partial products: .. math:: \prod_{i=1}^{n} f(i) = f(1) f(2) \cdots f(n) as n increases without bound. The product converges to a non-zero value if and only if the sum: .. math:: \sum_{1 \leq i < \infty} \log{f(n)} converges. Examples ======== >>> from sympy import Interval, S, Product, Symbol, cos, pi, exp, oo >>> n = Symbol('n', integer=True) >>> Product(n/(n + 1), (n, 1, oo)).is_convergent() False >>> Product(1/n**2, (n, 1, oo)).is_convergent() False >>> Product(cos(pi/n), (n, 1, oo)).is_convergent() True >>> Product(exp(-n**2), (n, 1, oo)).is_convergent() False References ========== .. [1] https://en.wikipedia.org/wiki/Infinite_product """ from sympy.concrete.summations import Sum sequence_term = self.function log_sum = log(sequence_term) lim = self.limits try: is_conv = Sum(log_sum, *lim).is_convergent() except NotImplementedError: if Sum(sequence_term - 1, *lim).is_absolutely_convergent() is S.true: return S.true raise NotImplementedError("The algorithm to find the product convergence of %s " "is not yet implemented" % (sequence_term)) return is_conv def reverse_order(expr, *indices): """ Reverse the order of a limit in a Product. Usage ===== ``reverse_order(expr, *indices)`` reverses some limits in the expression ``expr`` which can be either a ``Sum`` or a ``Product``. The selectors in the argument ``indices`` specify some indices whose limits get reversed. These selectors are either variable names or numerical indices counted starting from the inner-most limit tuple. Examples ======== >>> from sympy import Product, simplify, RisingFactorial, gamma, Sum >>> from sympy.abc import x, y, a, b, c, d >>> P = Product(x, (x, a, b)) >>> Pr = P.reverse_order(x) >>> Pr Product(1/x, (x, b + 1, a - 1)) >>> Pr = Pr.doit() >>> Pr 1/RisingFactorial(b + 1, a - b - 1) >>> simplify(Pr) gamma(b + 1)/gamma(a) >>> P = P.doit() >>> P RisingFactorial(a, -a + b + 1) >>> simplify(P) gamma(b + 1)/gamma(a) While one should prefer variable names when specifying which limits to reverse, the index counting notation comes in handy in case there are several symbols with the same name. >>> S = Sum(x*y, (x, a, b), (y, c, d)) >>> S Sum(x*y, (x, a, b), (y, c, d)) >>> S0 = S.reverse_order(0) >>> S0 Sum(-x*y, (x, b + 1, a - 1), (y, c, d)) >>> S1 = S0.reverse_order(1) >>> S1 Sum(x*y, (x, b + 1, a - 1), (y, d + 1, c - 1)) Of course we can mix both notations: >>> Sum(x*y, (x, a, b), (y, 2, 5)).reverse_order(x, 1) Sum(x*y, (x, b + 1, a - 1), (y, 6, 1)) >>> Sum(x*y, (x, a, b), (y, 2, 5)).reverse_order(y, x) Sum(x*y, (x, b + 1, a - 1), (y, 6, 1)) See Also ======== index, reorder_limit, reorder References ========== .. [1] Michael Karr, "Summation in Finite Terms", Journal of the ACM, Volume 28 Issue 2, April 1981, Pages 305-350 http://dl.acm.org/citation.cfm?doid=322248.322255 """ l_indices = list(indices) for i, indx in enumerate(l_indices): if not isinstance(indx, int): l_indices[i] = expr.index(indx) e = 1 limits = [] for i, limit in enumerate(expr.limits): l = limit if i in l_indices: e = -e l = (limit[0], limit[2] + 1, limit[1] - 1) limits.append(l) return Product(expr.function ** e, *limits) def product(*args, **kwargs): r""" Compute the product. The notation for symbols is similar to the notation used in Sum or Integral. product(f, (i, a, b)) computes the product of f with respect to i from a to b, i.e., :: b _____ product(f(n), (i, a, b)) = | | f(n) | | i = a If it cannot compute the product, it returns an unevaluated Product object. Repeated products can be computed by introducing additional symbols tuples:: >>> from sympy import product, symbols >>> i, n, m, k = symbols('i n m k', integer=True) >>> product(i, (i, 1, k)) factorial(k) >>> product(m, (i, 1, k)) m**k >>> product(i, (i, 1, k), (k, 1, n)) Product(factorial(k), (k, 1, n)) """ prod = Product(*args, **kwargs) if isinstance(prod, Product): return prod.doit(deep=False) else: return prod

7b7ec119ea92ce225fdca8ede27acf136610889074379e3c481576e53e09c75f

""" This module implements sums and products containing the Kronecker Delta function. References ========== - http://mathworld.wolfram.com/KroneckerDelta.html """ from __future__ import print_function, division from sympy.core import Add, Mul, S, Dummy from sympy.core.cache import cacheit from sympy.core.compatibility import default_sort_key, range from sympy.functions import KroneckerDelta, Piecewise, piecewise_fold from sympy.sets import Interval @cacheit def _expand_delta(expr, index): """ Expand the first Add containing a simple KroneckerDelta. """ if not expr.is_Mul: return expr delta = None func = Add terms = [S(1)] for h in expr.args: if delta is None and h.is_Add and _has_simple_delta(h, index): delta = True func = h.func terms = [terms[0]*t for t in h.args] else: terms = [t*h for t in terms] return func(*terms) @cacheit def _extract_delta(expr, index): """ Extract a simple KroneckerDelta from the expression. Returns the tuple ``(delta, newexpr)`` where: - ``delta`` is a simple KroneckerDelta expression if one was found, or ``None`` if no simple KroneckerDelta expression was found. - ``newexpr`` is a Mul containing the remaining terms; ``expr`` is returned unchanged if no simple KroneckerDelta expression was found. Examples ======== >>> from sympy import KroneckerDelta >>> from sympy.concrete.delta import _extract_delta >>> from sympy.abc import x, y, i, j, k >>> _extract_delta(4*x*y*KroneckerDelta(i, j), i) (KroneckerDelta(i, j), 4*x*y) >>> _extract_delta(4*x*y*KroneckerDelta(i, j), k) (None, 4*x*y*KroneckerDelta(i, j)) See Also ======== sympy.functions.special.tensor_functions.KroneckerDelta deltaproduct deltasummation """ if not _has_simple_delta(expr, index): return (None, expr) if isinstance(expr, KroneckerDelta): return (expr, S(1)) if not expr.is_Mul: raise ValueError("Incorrect expr") delta = None terms = [] for arg in expr.args: if delta is None and _is_simple_delta(arg, index): delta = arg else: terms.append(arg) return (delta, expr.func(*terms)) @cacheit def _has_simple_delta(expr, index): """ Returns True if ``expr`` is an expression that contains a KroneckerDelta that is simple in the index ``index``, meaning that this KroneckerDelta is nonzero for a single value of the index ``index``. """ if expr.has(KroneckerDelta): if _is_simple_delta(expr, index): return True if expr.is_Add or expr.is_Mul: for arg in expr.args: if _has_simple_delta(arg, index): return True return False @cacheit def _is_simple_delta(delta, index): """ Returns True if ``delta`` is a KroneckerDelta and is nonzero for a single value of the index ``index``. """ if isinstance(delta, KroneckerDelta) and delta.has(index): p = (delta.args[0] - delta.args[1]).as_poly(index) if p: return p.degree() == 1 return False @cacheit def _remove_multiple_delta(expr): """ Evaluate products of KroneckerDelta's. """ from sympy.solvers import solve if expr.is_Add: return expr.func(*list(map(_remove_multiple_delta, expr.args))) if not expr.is_Mul: return expr eqs = [] newargs = [] for arg in expr.args: if isinstance(arg, KroneckerDelta): eqs.append(arg.args[0] - arg.args[1]) else: newargs.append(arg) if not eqs: return expr solns = solve(eqs, dict=True) if len(solns) == 0: return S.Zero elif len(solns) == 1: for key in solns[0].keys(): newargs.append(KroneckerDelta(key, solns[0][key])) expr2 = expr.func(*newargs) if expr != expr2: return _remove_multiple_delta(expr2) return expr @cacheit def _simplify_delta(expr): """ Rewrite a KroneckerDelta's indices in its simplest form. """ from sympy.solvers import solve if isinstance(expr, KroneckerDelta): try: slns = solve(expr.args[0] - expr.args[1], dict=True) if slns and len(slns) == 1: return Mul(*[KroneckerDelta(*(key, value)) for key, value in slns[0].items()]) except NotImplementedError: pass return expr @cacheit def deltaproduct(f, limit): """ Handle products containing a KroneckerDelta. See Also ======== deltasummation sympy.functions.special.tensor_functions.KroneckerDelta sympy.concrete.products.product """ from sympy.concrete.products import product if ((limit[2] - limit[1]) < 0) == True: return S.One if not f.has(KroneckerDelta): return product(f, limit) if f.is_Add: # Identify the term in the Add that has a simple KroneckerDelta delta = None terms = [] for arg in sorted(f.args, key=default_sort_key): if delta is None and _has_simple_delta(arg, limit[0]): delta = arg else: terms.append(arg) newexpr = f.func(*terms) k = Dummy("kprime", integer=True) if isinstance(limit[1], int) and isinstance(limit[2], int): result = deltaproduct(newexpr, limit) + sum([ deltaproduct(newexpr, (limit[0], limit[1], ik - 1)) * delta.subs(limit[0], ik) * deltaproduct(newexpr, (limit[0], ik + 1, limit[2])) for ik in range(int(limit[1]), int(limit[2] + 1))] ) else: result = deltaproduct(newexpr, limit) + deltasummation( deltaproduct(newexpr, (limit[0], limit[1], k - 1)) * delta.subs(limit[0], k) * deltaproduct(newexpr, (limit[0], k + 1, limit[2])), (k, limit[1], limit[2]), no_piecewise=_has_simple_delta(newexpr, limit[0]) ) return _remove_multiple_delta(result) delta, _ = _extract_delta(f, limit[0]) if not delta: g = _expand_delta(f, limit[0]) if f != g: from sympy import factor try: return factor(deltaproduct(g, limit)) except AssertionError: return deltaproduct(g, limit) return product(f, limit) from sympy import Eq c = Eq(limit[2], limit[1] - 1) return _remove_multiple_delta(f.subs(limit[0], limit[1])*KroneckerDelta(limit[2], limit[1])) + \ S.One*_simplify_delta(KroneckerDelta(limit[2], limit[1] - 1)) @cacheit def deltasummation(f, limit, no_piecewise=False): """ Handle summations containing a KroneckerDelta. The idea for summation is the following: - If we are dealing with a KroneckerDelta expression, i.e. KroneckerDelta(g(x), j), we try to simplify it. If we could simplify it, then we sum the resulting expression. We already know we can sum a simplified expression, because only simple KroneckerDelta expressions are involved. If we couldn't simplify it, there are two cases: 1) The expression is a simple expression: we return the summation, taking care if we are dealing with a Derivative or with a proper KroneckerDelta. 2) The expression is not simple (i.e. KroneckerDelta(cos(x))): we can do nothing at all. - If the expr is a multiplication expr having a KroneckerDelta term: First we expand it. If the expansion did work, then we try to sum the expansion. If not, we try to extract a simple KroneckerDelta term, then we have two cases: 1) We have a simple KroneckerDelta term, so we return the summation. 2) We didn't have a simple term, but we do have an expression with simplified KroneckerDelta terms, so we sum this expression. Examples ======== >>> from sympy import oo, symbols >>> from sympy.abc import k >>> i, j = symbols('i, j', integer=True, finite=True) >>> from sympy.concrete.delta import deltasummation >>> from sympy import KroneckerDelta, Piecewise >>> deltasummation(KroneckerDelta(i, k), (k, -oo, oo)) 1 >>> deltasummation(KroneckerDelta(i, k), (k, 0, oo)) Piecewise((1, i >= 0), (0, True)) >>> deltasummation(KroneckerDelta(i, k), (k, 1, 3)) Piecewise((1, (i >= 1) & (i <= 3)), (0, True)) >>> deltasummation(k*KroneckerDelta(i, j)*KroneckerDelta(j, k), (k, -oo, oo)) j*KroneckerDelta(i, j) >>> deltasummation(j*KroneckerDelta(i, j), (j, -oo, oo)) i >>> deltasummation(i*KroneckerDelta(i, j), (i, -oo, oo)) j See Also ======== deltaproduct sympy.functions.special.tensor_functions.KroneckerDelta sympy.concrete.sums.summation """ from sympy.concrete.summations import summation from sympy.solvers import solve if ((limit[2] - limit[1]) < 0) == True: return S.Zero if not f.has(KroneckerDelta): return summation(f, limit) x = limit[0] g = _expand_delta(f, x) if g.is_Add: return piecewise_fold( g.func(*[deltasummation(h, limit, no_piecewise) for h in g.args])) # try to extract a simple KroneckerDelta term delta, expr = _extract_delta(g, x) if not delta: return summation(f, limit) solns = solve(delta.args[0] - delta.args[1], x) if len(solns) == 0: return S.Zero elif len(solns) != 1: from sympy.concrete.summations import Sum return Sum(f, limit) value = solns[0] if no_piecewise: return expr.subs(x, value) return Piecewise( (expr.subs(x, value), Interval(*limit[1:3]).as_relational(value)), (S.Zero, True) )

a97181c11f4e152b80739f6e343334679daae5fbf56be7f2ea927c6c24feffc0

"""Various algorithms for helping identifying numbers and sequences.""" from __future__ import print_function, division from sympy.utilities import public from sympy.core import Function, Symbol from sympy.core.compatibility import range from sympy.core.numbers import Zero from sympy import (sympify, floor, lcm, denom, Integer, Rational, exp, integrate, symbols, Product, product) from sympy.polys.polyfuncs import rational_interpolate as rinterp @public def find_simple_recurrence_vector(l): """ This function is used internally by other functions from the sympy.concrete.guess module. While most users may want to rather use the function find_simple_recurrence when looking for recurrence relations among rational numbers, the current function may still be useful when some post-processing has to be done. The function returns a vector of length n when a recurrence relation of order n is detected in the sequence of rational numbers v. If the returned vector has a length 1, then the returned value is always the list [0], which means that no relation has been found. While the functions is intended to be used with rational numbers, it should work for other kinds of real numbers except for some cases involving quadratic numbers; for that reason it should be used with some caution when the argument is not a list of rational numbers. Examples ======== >>> from sympy.concrete.guess import find_simple_recurrence_vector >>> from sympy import fibonacci >>> find_simple_recurrence_vector([fibonacci(k) for k in range(12)]) [1, -1, -1] See Also ======== See the function sympy.concrete.guess.find_simple_recurrence which is more user-friendly. """ q1 = [0] q2 = [Integer(1)] b, z = 0, len(l) >> 1 while len(q2) <= z: while l[b]==0: b += 1 if b == len(l): c = 1 for x in q2: c = lcm(c, denom(x)) if q2[0]*c < 0: c = -c for k in range(len(q2)): q2[k] = int(q2[k]*c) return q2 a = Integer(1)/l[b] m = [a] for k in range(b+1, len(l)): m.append(-sum(l[j+1]*m[b-j-1] for j in range(b, k))*a) l, m = m, [0] * max(len(q2), b+len(q1)) for k in range(len(q2)): m[k] = a*q2[k] for k in range(b, b+len(q1)): m[k] += q1[k-b] while m[-1]==0: m.pop() # because trailing zeros can occur q1, q2, b = q2, m, 1 return [0] @public def find_simple_recurrence(v, A=Function('a'), N=Symbol('n')): """ Detects and returns a recurrence relation from a sequence of several integer (or rational) terms. The name of the function in the returned expression is 'a' by default; the main variable is 'n' by default. The smallest index in the returned expression is always n (and never n-1, n-2, etc.). Examples ======== >>> from sympy.concrete.guess import find_simple_recurrence >>> from sympy import fibonacci >>> find_simple_recurrence([fibonacci(k) for k in range(12)]) -a(n) - a(n + 1) + a(n + 2) >>> from sympy import Function, Symbol >>> a = [1, 1, 1] >>> for k in range(15): a.append(5*a[-1]-3*a[-2]+8*a[-3]) >>> find_simple_recurrence(a, A=Function('f'), N=Symbol('i')) -8*f(i) + 3*f(i + 1) - 5*f(i + 2) + f(i + 3) """ p = find_simple_recurrence_vector(v) n = len(p) if n <= 1: return Zero() rel = Zero() for k in range(n): rel += A(N+n-1-k)*p[k] return rel @public def rationalize(x, maxcoeff=10000): """ Helps identifying a rational number from a float (or mpmath.mpf) value by using a continued fraction. The algorithm stops as soon as a large partial quotient is detected (greater than 10000 by default). Examples ======== >>> from sympy.concrete.guess import rationalize >>> from mpmath import cos, pi >>> rationalize(cos(pi/3)) 1/2 >>> from mpmath import mpf >>> rationalize(mpf("0.333333333333333")) 1/3 While the function is rather intended to help 'identifying' rational values, it may be used in some cases for approximating real numbers. (Though other functions may be more relevant in that case.) >>> rationalize(pi, maxcoeff = 250) 355/113 See Also ======== Several other methods can approximate a real number as a rational, like: * fractions.Fraction.from_decimal * fractions.Fraction.from_float * mpmath.identify * mpmath.pslq by using the following syntax: mpmath.pslq([x, 1]) * mpmath.findpoly by using the following syntax: mpmath.findpoly(x, 1) * sympy.simplify.nsimplify (which is a more general function) The main difference between the current function and all these variants is that control focuses on magnitude of partial quotients here rather than on global precision of the approximation. If the real is "known to be" a rational number, the current function should be able to detect it correctly with the default settings even when denominator is great (unless its expansion contains unusually big partial quotients) which may occur when studying sequences of increasing numbers. If the user cares more on getting simple fractions, other methods may be more convenient. """ p0, p1 = 0, 1 q0, q1 = 1, 0 a = floor(x) while a < maxcoeff or q1==0: p = a*p1 + p0 q = a*q1 + q0 p0, p1 = p1, p q0, q1 = q1, q if x==a: break x = 1/(x-a) a = floor(x) return sympify(p) / q @public def guess_generating_function_rational(v, X=Symbol('x')): """ Tries to "guess" a rational generating function for a sequence of rational numbers v. Examples ======== >>> from sympy.concrete.guess import guess_generating_function_rational >>> from sympy import fibonacci >>> l = [fibonacci(k) for k in range(5,15)] >>> guess_generating_function_rational(l) (3*x + 5)/(-x**2 - x + 1) See Also ======== sympy.series.approximants mpmath.pade """ # a) compute the denominator as q q = find_simple_recurrence_vector(v) n = len(q) if n <= 1: return None # b) compute the numerator as p p = [sum(v[i-k]*q[k] for k in range(min(i+1, n))) for i in range(len(v)>>1)] return (sum(p[k]*X**k for k in range(len(p))) / sum(q[k]*X**k for k in range(n))) @public def guess_generating_function(v, X=Symbol('x'), types=['all'], maxsqrtn=2): """ Tries to "guess" a generating function for a sequence of rational numbers v. Only a few patterns are implemented yet. The function returns a dictionary where keys are the name of a given type of generating function. Six types are currently implemented: type | formal definition -------+---------------------------------------------------------------- ogf | f(x) = Sum( a_k * x^k , k: 0..infinity ) egf | f(x) = Sum( a_k * x^k / k! , k: 0..infinity ) lgf | f(x) = Sum( (-1)^(k+1) a_k * x^k / k , k: 1..infinity ) | (with initial index being hold as 1 rather than 0) hlgf | f(x) = Sum( a_k * x^k / k , k: 1..infinity ) | (with initial index being hold as 1 rather than 0) lgdogf | f(x) = derivate( log(Sum( a_k * x^k, k: 0..infinity )), x) lgdegf | f(x) = derivate( log(Sum( a_k * x^k / k!, k: 0..infinity )), x) In order to spare time, the user can select only some types of generating functions (default being ['all']). While forgetting to use a list in the case of a single type may seem to work most of the time as in: types='ogf' this (convenient) syntax may lead to unexpected extra results in some cases. Discarding a type when calling the function does not mean that the type will not be present in the returned dictionary; it only means that no extra computation will be performed for that type, but the function may still add it in the result when it can be easily converted from another type. Two generating functions (lgdogf and lgdegf) are not even computed if the initial term of the sequence is 0; it may be useful in that case to try again after having removed the leading zeros. Examples ======== >>> from sympy.concrete.guess import guess_generating_function as ggf >>> ggf([k+1 for k in range(12)], types=['ogf', 'lgf', 'hlgf']) {'hlgf': 1/(-x + 1), 'lgf': 1/(x + 1), 'ogf': 1/(x**2 - 2*x + 1)} >>> from sympy import sympify >>> l = sympify("[3/2, 11/2, 0, -121/2, -363/2, 121]") >>> ggf(l) {'ogf': (x + 3/2)/(11*x**2 - 3*x + 1)} >>> from sympy import fibonacci >>> ggf([fibonacci(k) for k in range(5, 15)], types=['ogf']) {'ogf': (3*x + 5)/(-x**2 - x + 1)} >>> from sympy import simplify, factorial >>> ggf([factorial(k) for k in range(12)], types=['ogf', 'egf', 'lgf']) {'egf': 1/(-x + 1)} >>> ggf([k+1 for k in range(12)], types=['egf']) {'egf': (x + 1)*exp(x), 'lgdegf': (x + 2)/(x + 1)} N-th root of a rational function can also be detected (below is an example coming from the sequence A108626 from http://oeis.org). The greatest n-th root to be tested is specified as maxsqrtn (default 2). >>> ggf([1, 2, 5, 14, 41, 124, 383, 1200, 3799, 12122, 38919])['ogf'] sqrt(1/(x**4 + 2*x**2 - 4*x + 1)) References ========== .. [1] "Concrete Mathematics", R.L. Graham, D.E. Knuth, O. Patashnik .. [2] https://oeis.org/wiki/Generating_functions """ # List of all types of all g.f. known by the algorithm if 'all' in types: types = ['ogf', 'egf', 'lgf', 'hlgf', 'lgdogf', 'lgdegf'] result = {} # Ordinary Generating Function (ogf) if 'ogf' in types: # Perform some convolutions of the sequence with itself t = [1 if k==0 else 0 for k in range(len(v))] for d in range(max(1, maxsqrtn)): t = [sum(t[n-i]*v[i] for i in range(n+1)) for n in range(len(v))] g = guess_generating_function_rational(t, X=X) if g: result['ogf'] = g**Rational(1, d+1) break # Exponential Generating Function (egf) if 'egf' in types: # Transform sequence (division by factorial) w, f = [], Integer(1) for i, k in enumerate(v): f *= i if i else 1 w.append(k/f) # Perform some convolutions of the sequence with itself t = [1 if k==0 else 0 for k in range(len(w))] for d in range(max(1, maxsqrtn)): t = [sum(t[n-i]*w[i] for i in range(n+1)) for n in range(len(w))] g = guess_generating_function_rational(t, X=X) if g: result['egf'] = g**Rational(1, d+1) break # Logarithmic Generating Function (lgf) if 'lgf' in types: # Transform sequence (multiplication by (-1)^(n+1) / n) w, f = [], Integer(-1) for i, k in enumerate(v): f = -f w.append(f*k/Integer(i+1)) # Perform some convolutions of the sequence with itself t = [1 if k==0 else 0 for k in range(len(w))] for d in range(max(1, maxsqrtn)): t = [sum(t[n-i]*w[i] for i in range(n+1)) for n in range(len(w))] g = guess_generating_function_rational(t, X=X) if g: result['lgf'] = g**Rational(1, d+1) break # Hyperbolic logarithmic Generating Function (hlgf) if 'hlgf' in types: # Transform sequence (division by n+1) w = [] for i, k in enumerate(v): w.append(k/Integer(i+1)) # Perform some convolutions of the sequence with itself t = [1 if k==0 else 0 for k in range(len(w))] for d in range(max(1, maxsqrtn)): t = [sum(t[n-i]*w[i] for i in range(n+1)) for n in range(len(w))] g = guess_generating_function_rational(t, X=X) if g: result['hlgf'] = g**Rational(1, d+1) break # Logarithmic derivative of ordinary generating Function (lgdogf) if v[0] != 0 and ('lgdogf' in types or ('ogf' in types and 'ogf' not in result)): # Transform sequence by computing f'(x)/f(x) # because log(f(x)) = integrate( f'(x)/f(x) ) a, w = sympify(v[0]), [] for n in range(len(v)-1): w.append( (v[n+1]*(n+1) - sum(w[-i-1]*v[i+1] for i in range(n)))/a) # Perform some convolutions of the sequence with itself t = [1 if k==0 else 0 for k in range(len(w))] for d in range(max(1, maxsqrtn)): t = [sum(t[n-i]*w[i] for i in range(n+1)) for n in range(len(w))] g = guess_generating_function_rational(t, X=X) if g: result['lgdogf'] = g**Rational(1, d+1) if 'ogf' not in result: result['ogf'] = exp(integrate(result['lgdogf'], X)) break # Logarithmic derivative of exponential generating Function (lgdegf) if v[0] != 0 and ('lgdegf' in types or ('egf' in types and 'egf' not in result)): # Transform sequence / step 1 (division by factorial) z, f = [], Integer(1) for i, k in enumerate(v): f *= i if i else 1 z.append(k/f) # Transform sequence / step 2 by computing f'(x)/f(x) # because log(f(x)) = integrate( f'(x)/f(x) ) a, w = z[0], [] for n in range(len(z)-1): w.append( (z[n+1]*(n+1) - sum(w[-i-1]*z[i+1] for i in range(n)))/a) # Perform some convolutions of the sequence with itself t = [1 if k==0 else 0 for k in range(len(w))] for d in range(max(1, maxsqrtn)): t = [sum(t[n-i]*w[i] for i in range(n+1)) for n in range(len(w))] g = guess_generating_function_rational(t, X=X) if g: result['lgdegf'] = g**Rational(1, d+1) if 'egf' not in result: result['egf'] = exp(integrate(result['lgdegf'], X)) break return result @public def guess(l, all=False, evaluate=True, niter=2, variables=None): """ This function is adapted from the Rate.m package for Mathematica written by Christian Krattenthaler. It tries to guess a formula from a given sequence of rational numbers. In order to speed up the process, the 'all' variable is set to False by default, stopping the computation as some results are returned during an iteration; the variable can be set to True if more iterations are needed (other formulas may be found; however they may be equivalent to the first ones). Another option is the 'evaluate' variable (default is True); setting it to False will leave the involved products unevaluated. By default, the number of iterations is set to 2 but a greater value (up to len(l)-1) can be specified with the optional 'niter' variable. More and more convoluted results are found when the order of the iteration gets higher: * first iteration returns polynomial or rational functions; * second iteration returns products of rising factorials and their inverses; * third iteration returns products of products of rising factorials and their inverses; * etc. The returned formulas contain symbols i0, i1, i2, ... where the main variables is i0 (and auxiliary variables are i1, i2, ...). A list of other symbols can be provided in the 'variables' option; the length of the least should be the value of 'niter' (more is acceptable but only the first symbols will be used); in this case, the main variable will be the first symbol in the list. Examples ======== >>> from sympy.concrete.guess import guess >>> guess([1,2,6,24,120], evaluate=False) [Product(i1 + 1, (i1, 1, i0 - 1))] >>> from sympy import symbols >>> r = guess([1,2,7,42,429,7436,218348,10850216], niter=4) >>> i0 = symbols("i0") >>> [r[0].subs(i0,n).doit() for n in range(1,10)] [1, 2, 7, 42, 429, 7436, 218348, 10850216, 911835460] """ if any(a==0 for a in l[:-1]): return [] N = len(l) niter = min(N-1, niter) myprod = product if evaluate else Product g = [] res = [] if variables == None: symb = symbols('i:'+str(niter)) else: symb = variables for k, s in enumerate(symb): g.append(l) n, r = len(l), [] for i in range(n-2-1, -1, -1): ri = rinterp(enumerate(g[k][:-1], start=1), i, X=s) if ((denom(ri).subs({s:n}) != 0) and (ri.subs({s:n}) - g[k][-1] == 0) and ri not in r): r.append(ri) if r: for i in range(k-1, -1, -1): r = list(map(lambda v: g[i][0] * myprod(v, (symb[i+1], 1, symb[i]-1)), r)) if not all: return r res += r l = [Rational(l[i+1], l[i]) for i in range(N-k-1)] return res

83c71d1e87e856e517f56085ef62d6ec4bf02db3fc7038f7ec80edef64b8804d

from __future__ import print_function, division from sympy.core.add import Add from sympy.core.compatibility import is_sequence from sympy.core.containers import Tuple from sympy.core.expr import Expr from sympy.core.mul import Mul from sympy.core.relational import Equality, Relational from sympy.core.singleton import S from sympy.core.symbol import Symbol, Dummy from sympy.core.sympify import sympify from sympy.functions.elementary.piecewise import (piecewise_fold, Piecewise) from sympy.logic.boolalg import BooleanFunction from sympy.matrices import Matrix from sympy.tensor.indexed import Idx from sympy.sets.sets import Interval from sympy.utilities import flatten from sympy.utilities.iterables import sift def _common_new(cls, function, *symbols, **assumptions): """Return either a special return value or the tuple, (function, limits, orientation). This code is common to both ExprWithLimits and AddWithLimits.""" function = sympify(function) if hasattr(function, 'func') and isinstance(function, Equality): lhs = function.lhs rhs = function.rhs return Equality(cls(lhs, *symbols, **assumptions), \ cls(rhs, *symbols, **assumptions)) if function is S.NaN: return S.NaN if symbols: limits, orientation = _process_limits(*symbols) else: # symbol not provided -- we can still try to compute a general form free = function.free_symbols if len(free) != 1: raise ValueError( "specify dummy variables for %s" % function) limits, orientation = [Tuple(s) for s in free], 1 # denest any nested calls while cls == type(function): limits = list(function.limits) + limits function = function.function # Any embedded piecewise functions need to be brought out to the # top level. We only fold Piecewise that contain the integration # variable. reps = {} symbols_of_integration = set([i[0] for i in limits]) for p in function.atoms(Piecewise): if not p.has(*symbols_of_integration): reps[p] = Dummy() # mask off those that don't function = function.xreplace(reps) # do the fold function = piecewise_fold(function) # remove the masking function = function.xreplace({v: k for k, v in reps.items()}) return function, limits, orientation def _process_limits(*symbols): """Process the list of symbols and convert them to canonical limits, storing them as Tuple(symbol, lower, upper). The orientation of the function is also returned when the upper limit is missing so (x, 1, None) becomes (x, None, 1) and the orientation is changed. """ limits = [] orientation = 1 for V in symbols: if isinstance(V, (Relational, BooleanFunction)): variable = V.atoms(Symbol).pop() V = (variable, V.as_set()) if isinstance(V, Symbol) or getattr(V, '_diff_wrt', False): if isinstance(V, Idx): if V.lower is None or V.upper is None: limits.append(Tuple(V)) else: limits.append(Tuple(V, V.lower, V.upper)) else: limits.append(Tuple(V)) continue elif is_sequence(V, Tuple): V = sympify(flatten(V)) if isinstance(V[0], (Symbol, Idx)) or getattr(V[0], '_diff_wrt', False): newsymbol = V[0] if len(V) == 2 and isinstance(V[1], Interval): V[1:] = [V[1].start, V[1].end] if len(V) == 3: if V[1] is None and V[2] is not None: nlim = [V[2]] elif V[1] is not None and V[2] is None: orientation *= -1 nlim = [V[1]] elif V[1] is None and V[2] is None: nlim = [] else: nlim = V[1:] limits.append(Tuple(newsymbol, *nlim)) if isinstance(V[0], Idx): if V[0].lower is not None and not bool(nlim[0] >= V[0].lower): raise ValueError("Summation exceeds Idx lower range.") if V[0].upper is not None and not bool(nlim[1] <= V[0].upper): raise ValueError("Summation exceeds Idx upper range.") continue elif len(V) == 1 or (len(V) == 2 and V[1] is None): limits.append(Tuple(newsymbol)) continue elif len(V) == 2: limits.append(Tuple(newsymbol, V[1])) continue raise ValueError('Invalid limits given: %s' % str(symbols)) return limits, orientation class ExprWithLimits(Expr): __slots__ = ['is_commutative'] def __new__(cls, function, *symbols, **assumptions): pre = _common_new(cls, function, *symbols, **assumptions) if type(pre) is tuple: function, limits, _ = pre else: return pre # limits must have upper and lower bounds; the indefinite form # is not supported. This restriction does not apply to AddWithLimits if any(len(l) != 3 or None in l for l in limits): raise ValueError('ExprWithLimits requires values for lower and upper bounds.') obj = Expr.__new__(cls, **assumptions) arglist = [function] arglist.extend(limits) obj._args = tuple(arglist) obj.is_commutative = function.is_commutative # limits already checked return obj @property def function(self): """Return the function applied across limits. Examples ======== >>> from sympy import Integral >>> from sympy.abc import x >>> Integral(x**2, (x,)).function x**2 See Also ======== limits, variables, free_symbols """ return self._args[0] @property def limits(self): """Return the limits of expression. Examples ======== >>> from sympy import Integral >>> from sympy.abc import x, i >>> Integral(x**i, (i, 1, 3)).limits ((i, 1, 3),) See Also ======== function, variables, free_symbols """ return self._args[1:] @property def variables(self): """Return a list of the limit variables. >>> from sympy import Sum >>> from sympy.abc import x, i >>> Sum(x**i, (i, 1, 3)).variables [i] See Also ======== function, limits, free_symbols as_dummy : Rename dummy variables transform : Perform mapping on the dummy variable """ return [l[0] for l in self.limits] @property def bound_symbols(self): """Return only variables that are dummy variables. Examples ======== >>> from sympy import Integral >>> from sympy.abc import x, i, j, k >>> Integral(x**i, (i, 1, 3), (j, 2), k).bound_symbols [i, j] See Also ======== function, limits, free_symbols as_dummy : Rename dummy variables transform : Perform mapping on the dummy variable """ return [l[0] for l in self.limits if len(l) != 1] @property def free_symbols(self): """ This method returns the symbols in the object, excluding those that take on a specific value (i.e. the dummy symbols). Examples ======== >>> from sympy import Sum >>> from sympy.abc import x, y >>> Sum(x, (x, y, 1)).free_symbols {y} """ # don't test for any special values -- nominal free symbols # should be returned, e.g. don't return set() if the # function is zero -- treat it like an unevaluated expression. function, limits = self.function, self.limits isyms = function.free_symbols for xab in limits: if len(xab) == 1: isyms.add(xab[0]) continue # take out the target symbol if xab[0] in isyms: isyms.remove(xab[0]) # add in the new symbols for i in xab[1:]: isyms.update(i.free_symbols) return isyms @property def is_number(self): """Return True if the Sum has no free symbols, else False.""" return not self.free_symbols def _eval_interval(self, x, a, b): limits = [(i if i[0] != x else (x, a, b)) for i in self.limits] integrand = self.function return self.func(integrand, *limits) def _eval_subs(self, old, new): """ Perform substitutions over non-dummy variables of an expression with limits. Also, can be used to specify point-evaluation of an abstract antiderivative. Examples ======== >>> from sympy import Sum, oo >>> from sympy.abc import s, n >>> Sum(1/n**s, (n, 1, oo)).subs(s, 2) Sum(n**(-2), (n, 1, oo)) >>> from sympy import Integral >>> from sympy.abc import x, a >>> Integral(a*x**2, x).subs(x, 4) Integral(a*x**2, (x, 4)) See Also ======== variables : Lists the integration variables transform : Perform mapping on the dummy variable for integrals change_index : Perform mapping on the sum and product dummy variables """ from sympy.core.function import AppliedUndef, UndefinedFunction func, limits = self.function, list(self.limits) # If one of the expressions we are replacing is used as a func index # one of two things happens. # - the old variable first appears as a free variable # so we perform all free substitutions before it becomes # a func index. # - the old variable first appears as a func index, in # which case we ignore. See change_index. # Reorder limits to match standard mathematical practice for scoping limits.reverse() if not isinstance(old, Symbol) or \ old.free_symbols.intersection(self.free_symbols): sub_into_func = True for i, xab in enumerate(limits): if 1 == len(xab) and old == xab[0]: if new._diff_wrt: xab = (new,) else: xab = (old, old) limits[i] = Tuple(xab[0], *[l._subs(old, new) for l in xab[1:]]) if len(xab[0].free_symbols.intersection(old.free_symbols)) != 0: sub_into_func = False break if isinstance(old, AppliedUndef) or isinstance(old, UndefinedFunction): sy2 = set(self.variables).intersection(set(new.atoms(Symbol))) sy1 = set(self.variables).intersection(set(old.args)) if not sy2.issubset(sy1): raise ValueError( "substitution can not create dummy dependencies") sub_into_func = True if sub_into_func: func = func.subs(old, new) else: # old is a Symbol and a dummy variable of some limit for i, xab in enumerate(limits): if len(xab) == 3: limits[i] = Tuple(xab[0], *[l._subs(old, new) for l in xab[1:]]) if old == xab[0]: break # simplify redundant limits (x, x) to (x, ) for i, xab in enumerate(limits): if len(xab) == 2 and (xab[0] - xab[1]).is_zero: limits[i] = Tuple(xab[0], ) # Reorder limits back to representation-form limits.reverse() return self.func(func, *limits) class AddWithLimits(ExprWithLimits): r"""Represents unevaluated oriented additions. Parent class for Integral and Sum. """ def __new__(cls, function, *symbols, **assumptions): pre = _common_new(cls, function, *symbols, **assumptions) if type(pre) is tuple: function, limits, orientation = pre else: return pre obj = Expr.__new__(cls, **assumptions) arglist = [orientation*function] # orientation not used in ExprWithLimits arglist.extend(limits) obj._args = tuple(arglist) obj.is_commutative = function.is_commutative # limits already checked return obj def _eval_adjoint(self): if all([x.is_real for x in flatten(self.limits)]): return self.func(self.function.adjoint(), *self.limits) return None def _eval_conjugate(self): if all([x.is_real for x in flatten(self.limits)]): return self.func(self.function.conjugate(), *self.limits) return None def _eval_transpose(self): if all([x.is_real for x in flatten(self.limits)]): return self.func(self.function.transpose(), *self.limits) return None def _eval_factor(self, **hints): if 1 == len(self.limits): summand = self.function.factor(**hints) if summand.is_Mul: out = sift(summand.args, lambda w: w.is_commutative \ and not set(self.variables) & w.free_symbols) return Mul(*out[True])*self.func(Mul(*out[False]), \ *self.limits) else: summand = self.func(self.function, *self.limits[0:-1]).factor() if not summand.has(self.variables[-1]): return self.func(1, [self.limits[-1]]).doit()*summand elif isinstance(summand, Mul): return self.func(summand, self.limits[-1]).factor() return self def _eval_expand_basic(self, **hints): summand = self.function.expand(**hints) if summand.is_Add and summand.is_commutative: return Add(*[self.func(i, *self.limits) for i in summand.args]) elif summand.is_Matrix: return Matrix._new(summand.rows, summand.cols, [self.func(i, *self.limits) for i in summand._mat]) elif summand != self.function: return self.func(summand, *self.limits) return self

d774bc1c3217a0df1f74a685ed8b01acc82e1fa3ee117f3cec35c5a2be21319b

from __future__ import print_function, division from sympy.calculus.singularities import is_decreasing from sympy.calculus.util import AccumulationBounds from sympy.concrete.expr_with_limits import AddWithLimits from sympy.concrete.expr_with_intlimits import ExprWithIntLimits from sympy.concrete.gosper import gosper_sum from sympy.core.add import Add from sympy.core.compatibility import range from sympy.core.function import Derivative from sympy.core.mul import Mul from sympy.core.relational import Eq from sympy.core.singleton import S from sympy.core.symbol import Dummy, Wild, Symbol from sympy.functions.special.zeta_functions import zeta from sympy.functions.elementary.piecewise import Piecewise from sympy.logic.boolalg import And from sympy.polys import apart, PolynomialError, together from sympy.series.limitseq import limit_seq from sympy.series.order import O from sympy.sets.sets import FiniteSet from sympy.simplify import denom from sympy.simplify.combsimp import combsimp from sympy.simplify.powsimp import powsimp from sympy.solvers import solve from sympy.solvers.solveset import solveset import itertools class Sum(AddWithLimits, ExprWithIntLimits): r"""Represents unevaluated summation. ``Sum`` represents a finite or infinite series, with the first argument being the general form of terms in the series, and the second argument being ``(dummy_variable, start, end)``, with ``dummy_variable`` taking all integer values from ``start`` through ``end``. In accordance with long-standing mathematical convention, the end term is included in the summation. Finite sums =========== For finite sums (and sums with symbolic limits assumed to be finite) we follow the summation convention described by Karr [1], especially definition 3 of section 1.4. The sum: .. math:: \sum_{m \leq i < n} f(i) has *the obvious meaning* for `m < n`, namely: .. math:: \sum_{m \leq i < n} f(i) = f(m) + f(m+1) + \ldots + f(n-2) + f(n-1) with the upper limit value `f(n)` excluded. The sum over an empty set is zero if and only if `m = n`: .. math:: \sum_{m \leq i < n} f(i) = 0 \quad \mathrm{for} \quad m = n Finally, for all other sums over empty sets we assume the following definition: .. math:: \sum_{m \leq i < n} f(i) = - \sum_{n \leq i < m} f(i) \quad \mathrm{for} \quad m > n It is important to note that Karr defines all sums with the upper limit being exclusive. This is in contrast to the usual mathematical notation, but does not affect the summation convention. Indeed we have: .. math:: \sum_{m \leq i < n} f(i) = \sum_{i = m}^{n - 1} f(i) where the difference in notation is intentional to emphasize the meaning, with limits typeset on the top being inclusive. Examples ======== >>> from sympy.abc import i, k, m, n, x >>> from sympy import Sum, factorial, oo, IndexedBase, Function >>> Sum(k, (k, 1, m)) Sum(k, (k, 1, m)) >>> Sum(k, (k, 1, m)).doit() m**2/2 + m/2 >>> Sum(k**2, (k, 1, m)) Sum(k**2, (k, 1, m)) >>> Sum(k**2, (k, 1, m)).doit() m**3/3 + m**2/2 + m/6 >>> Sum(x**k, (k, 0, oo)) Sum(x**k, (k, 0, oo)) >>> Sum(x**k, (k, 0, oo)).doit() Piecewise((1/(-x + 1), Abs(x) < 1), (Sum(x**k, (k, 0, oo)), True)) >>> Sum(x**k/factorial(k), (k, 0, oo)).doit() exp(x) Here are examples to do summation with symbolic indices. You can use either Function of IndexedBase classes: >>> f = Function('f') >>> Sum(f(n), (n, 0, 3)).doit() f(0) + f(1) + f(2) + f(3) >>> Sum(f(n), (n, 0, oo)).doit() Sum(f(n), (n, 0, oo)) >>> f = IndexedBase('f') >>> Sum(f[n]**2, (n, 0, 3)).doit() f[0]**2 + f[1]**2 + f[2]**2 + f[3]**2 An example showing that the symbolic result of a summation is still valid for seemingly nonsensical values of the limits. Then the Karr convention allows us to give a perfectly valid interpretation to those sums by interchanging the limits according to the above rules: >>> S = Sum(i, (i, 1, n)).doit() >>> S n**2/2 + n/2 >>> S.subs(n, -4) 6 >>> Sum(i, (i, 1, -4)).doit() 6 >>> Sum(-i, (i, -3, 0)).doit() 6 An explicit example of the Karr summation convention: >>> S1 = Sum(i**2, (i, m, m+n-1)).doit() >>> S1 m**2*n + m*n**2 - m*n + n**3/3 - n**2/2 + n/6 >>> S2 = Sum(i**2, (i, m+n, m-1)).doit() >>> S2 -m**2*n - m*n**2 + m*n - n**3/3 + n**2/2 - n/6 >>> S1 + S2 0 >>> S3 = Sum(i, (i, m, m-1)).doit() >>> S3 0 See Also ======== summation Product, product References ========== .. [1] Michael Karr, "Summation in Finite Terms", Journal of the ACM, Volume 28 Issue 2, April 1981, Pages 305-350 http://dl.acm.org/citation.cfm?doid=322248.322255 .. [2] https://en.wikipedia.org/wiki/Summation#Capital-sigma_notation .. [3] https://en.wikipedia.org/wiki/Empty_sum """ __slots__ = ['is_commutative'] def __new__(cls, function, *symbols, **assumptions): obj = AddWithLimits.__new__(cls, function, *symbols, **assumptions) if not hasattr(obj, 'limits'): return obj if any(len(l) != 3 or None in l for l in obj.limits): raise ValueError('Sum requires values for lower and upper bounds.') return obj def _eval_is_zero(self): # a Sum is only zero if its function is zero or if all terms # cancel out. This only answers whether the summand is zero; if # not then None is returned since we don't analyze whether all # terms cancel out. if self.function.is_zero: return True def doit(self, **hints): if hints.get('deep', True): f = self.function.doit(**hints) else: f = self.function if self.function.is_Matrix: return self.expand().doit() for n, limit in enumerate(self.limits): i, a, b = limit dif = b - a if dif.is_integer and (dif < 0) == True: a, b = b + 1, a - 1 f = -f newf = eval_sum(f, (i, a, b)) if newf is None: if f == self.function: zeta_function = self.eval_zeta_function(f, (i, a, b)) if zeta_function is not None: return zeta_function return self else: return self.func(f, *self.limits[n:]) f = newf if hints.get('deep', True): # eval_sum could return partially unevaluated # result with Piecewise. In this case we won't # doit() recursively. if not isinstance(f, Piecewise): return f.doit(**hints) return f def eval_zeta_function(self, f, limits): """ Check whether the function matches with the zeta function. If it matches, then return a `Piecewise` expression because zeta function does not converge unless `s > 1` and `q > 0` """ i, a, b = limits w, y, z = Wild('w', exclude=[i]), Wild('y', exclude=[i]), Wild('z', exclude=[i]) result = f.match((w * i + y) ** (-z)) if result is not None and b == S.Infinity: coeff = 1 / result[w] ** result[z] s = result[z] q = result[y] / result[w] + a return Piecewise((coeff * zeta(s, q), And(q > 0, s > 1)), (self, True)) def _eval_derivative(self, x): """ Differentiate wrt x as long as x is not in the free symbols of any of the upper or lower limits. Sum(a*b*x, (x, 1, a)) can be differentiated wrt x or b but not `a` since the value of the sum is discontinuous in `a`. In a case involving a limit variable, the unevaluated derivative is returned. """ # diff already confirmed that x is in the free symbols of self, but we # don't want to differentiate wrt any free symbol in the upper or lower # limits # XXX remove this test for free_symbols when the default _eval_derivative is in if isinstance(x, Symbol) and x not in self.free_symbols: return S.Zero # get limits and the function f, limits = self.function, list(self.limits) limit = limits.pop(-1) if limits: # f is the argument to a Sum f = self.func(f, *limits) if len(limit) == 3: _, a, b = limit if x in a.free_symbols or x in b.free_symbols: return None df = Derivative(f, x, evaluate=True) rv = self.func(df, limit) return rv else: return NotImplementedError('Lower and upper bound expected.') def _eval_difference_delta(self, n, step): k, _, upper = self.args[-1] new_upper = upper.subs(n, n + step) if len(self.args) == 2: f = self.args[0] else: f = self.func(*self.args[:-1]) return Sum(f, (k, upper + 1, new_upper)).doit() def _eval_simplify(self, ratio=1.7, measure=None, rational=False, inverse=False): from sympy.simplify.simplify import factor_sum, sum_combine from sympy.core.function import expand from sympy.core.mul import Mul # split the function into adds terms = Add.make_args(expand(self.function)) s_t = [] # Sum Terms o_t = [] # Other Terms for term in terms: if term.has(Sum): # if there is an embedded sum here # it is of the form x * (Sum(whatever)) # hence we make a Mul out of it, and simplify all interior sum terms subterms = Mul.make_args(expand(term)) out_terms = [] for subterm in subterms: # go through each term if isinstance(subterm, Sum): # if it's a sum, simplify it out_terms.append(subterm._eval_simplify()) else: # otherwise, add it as is out_terms.append(subterm) # turn it back into a Mul s_t.append(Mul(*out_terms)) else: o_t.append(term) # next try to combine any interior sums for further simplification result = Add(sum_combine(s_t), *o_t) return factor_sum(result, limits=self.limits) def _eval_summation(self, f, x): return None def is_convergent(self): r"""Checks for the convergence of a Sum. We divide the study of convergence of infinite sums and products in two parts. First Part: One part is the question whether all the terms are well defined, i.e., they are finite in a sum and also non-zero in a product. Zero is the analogy of (minus) infinity in products as :math:`e^{-\infty} = 0`. Second Part: The second part is the question of convergence after infinities, and zeros in products, have been omitted assuming that their number is finite. This means that we only consider the tail of the sum or product, starting from some point after which all terms are well defined. For example, in a sum of the form: .. math:: \sum_{1 \leq i < \infty} \frac{1}{n^2 + an + b} where a and b are numbers. The routine will return true, even if there are infinities in the term sequence (at most two). An analogous product would be: .. math:: \prod_{1 \leq i < \infty} e^{\frac{1}{n^2 + an + b}} This is how convergence is interpreted. It is concerned with what happens at the limit. Finding the bad terms is another independent matter. Note: It is responsibility of user to see that the sum or product is well defined. There are various tests employed to check the convergence like divergence test, root test, integral test, alternating series test, comparison tests, Dirichlet tests. It returns true if Sum is convergent and false if divergent and NotImplementedError if it can not be checked. References ========== .. [1] https://en.wikipedia.org/wiki/Convergence_tests Examples ======== >>> from sympy import factorial, S, Sum, Symbol, oo >>> n = Symbol('n', integer=True) >>> Sum(n/(n - 1), (n, 4, 7)).is_convergent() True >>> Sum(n/(2*n + 1), (n, 1, oo)).is_convergent() False >>> Sum(factorial(n)/5**n, (n, 1, oo)).is_convergent() False >>> Sum(1/n**(S(6)/5), (n, 1, oo)).is_convergent() True See Also ======== Sum.is_absolutely_convergent() Product.is_convergent() """ from sympy import Interval, Integral, log, symbols, simplify p, q, r = symbols('p q r', cls=Wild) sym = self.limits[0][0] lower_limit = self.limits[0][1] upper_limit = self.limits[0][2] sequence_term = self.function if len(sequence_term.free_symbols) > 1: raise NotImplementedError("convergence checking for more than one symbol " "containing series is not handled") if lower_limit.is_finite and upper_limit.is_finite: return S.true # transform sym -> -sym and swap the upper_limit = S.Infinity # and lower_limit = - upper_limit if lower_limit is S.NegativeInfinity: if upper_limit is S.Infinity: return Sum(sequence_term, (sym, 0, S.Infinity)).is_convergent() and \ Sum(sequence_term, (sym, S.NegativeInfinity, 0)).is_convergent() sequence_term = simplify(sequence_term.xreplace({sym: -sym})) lower_limit = -upper_limit upper_limit = S.Infinity sym_ = Dummy(sym.name, integer=True, positive=True) sequence_term = sequence_term.xreplace({sym: sym_}) sym = sym_ interval = Interval(lower_limit, upper_limit) # Piecewise function handle if sequence_term.is_Piecewise: for func, cond in sequence_term.args: # see if it represents something going to oo if cond == True or cond.as_set().sup is S.Infinity: s = Sum(func, (sym, lower_limit, upper_limit)) return s.is_convergent() return S.true ### -------- Divergence test ----------- ### try: lim_val = limit_seq(sequence_term, sym) if lim_val is not None and lim_val.is_zero is False: return S.false except NotImplementedError: pass try: lim_val_abs = limit_seq(abs(sequence_term), sym) if lim_val_abs is not None and lim_val_abs.is_zero is False: return S.false except NotImplementedError: pass order = O(sequence_term, (sym, S.Infinity)) ### --------- p-series test (1/n**p) ---------- ### p1_series_test = order.expr.match(sym**p) if p1_series_test is not None: if p1_series_test[p] < -1: return S.true if p1_series_test[p] >= -1: return S.false p2_series_test = order.expr.match((1/sym)**p) if p2_series_test is not None: if p2_series_test[p] > 1: return S.true if p2_series_test[p] <= 1: return S.false ### ------------- comparison test ------------- ### # 1/(n**p*log(n)**q*log(log(n))**r) comparison n_log_test = order.expr.match(1/(sym**p*log(sym)**q*log(log(sym))**r)) if n_log_test is not None: if (n_log_test[p] > 1 or (n_log_test[p] == 1 and n_log_test[q] > 1) or (n_log_test[p] == n_log_test[q] == 1 and n_log_test[r] > 1)): return S.true return S.false ### ------------- Limit comparison test -----------### # (1/n) comparison try: lim_comp = limit_seq(sym*sequence_term, sym) if lim_comp is not None and lim_comp.is_number and lim_comp > 0: return S.false except NotImplementedError: pass ### ----------- ratio test ---------------- ### next_sequence_term = sequence_term.xreplace({sym: sym + 1}) ratio = combsimp(powsimp(next_sequence_term/sequence_term)) try: lim_ratio = limit_seq(ratio, sym) if lim_ratio is not None and lim_ratio.is_number: if abs(lim_ratio) > 1: return S.false if abs(lim_ratio) < 1: return S.true except NotImplementedError: pass ### ----------- root test ---------------- ### # lim = Limit(abs(sequence_term)**(1/sym), sym, S.Infinity) try: lim_evaluated = limit_seq(abs(sequence_term)**(1/sym), sym) if lim_evaluated is not None and lim_evaluated.is_number: if lim_evaluated < 1: return S.true if lim_evaluated > 1: return S.false except NotImplementedError: pass ### ------------- alternating series test ----------- ### dict_val = sequence_term.match((-1)**(sym + p)*q) if not dict_val[p].has(sym) and is_decreasing(dict_val[q], interval): return S.true ### ------------- integral test -------------- ### check_interval = None maxima = solveset(sequence_term.diff(sym), sym, interval) if not maxima: check_interval = interval elif isinstance(maxima, FiniteSet) and maxima.sup.is_number: check_interval = Interval(maxima.sup, interval.sup) if (check_interval is not None and (is_decreasing(sequence_term, check_interval) or is_decreasing(-sequence_term, check_interval))): integral_val = Integral( sequence_term, (sym, lower_limit, upper_limit)) try: integral_val_evaluated = integral_val.doit() if integral_val_evaluated.is_number: return S(integral_val_evaluated.is_finite) except NotImplementedError: pass ### ----- Dirichlet and bounded times convergent tests ----- ### # TODO # # Dirichlet_test # https://en.wikipedia.org/wiki/Dirichlet%27s_test # # Bounded times convergent test # It is based on comparison theorems for series. # In particular, if the general term of a series can # be written as a product of two terms a_n and b_n # and if a_n is bounded and if Sum(b_n) is absolutely # convergent, then the original series Sum(a_n * b_n) # is absolutely convergent and so convergent. # # The following code can grows like 2**n where n is the # number of args in order.expr # Possibly combined with the potentially slow checks # inside the loop, could make this test extremely slow # for larger summation expressions. if order.expr.is_Mul: args = order.expr.args argset = set(args) ### -------------- Dirichlet tests -------------- ### m = Dummy('m', integer=True) def _dirichlet_test(g_n): try: ing_val = limit_seq(Sum(g_n, (sym, interval.inf, m)).doit(), m) if ing_val is not None and ing_val.is_finite: return S.true except NotImplementedError: pass ### -------- bounded times convergent test ---------### def _bounded_convergent_test(g1_n, g2_n): try: lim_val = limit_seq(g1_n, sym) if lim_val is not None and (lim_val.is_finite or ( isinstance(lim_val, AccumulationBounds) and (lim_val.max - lim_val.min).is_finite)): if Sum(g2_n, (sym, lower_limit, upper_limit)).is_absolutely_convergent(): return S.true except NotImplementedError: pass for n in range(1, len(argset)): for a_tuple in itertools.combinations(args, n): b_set = argset - set(a_tuple) a_n = Mul(*a_tuple) b_n = Mul(*b_set) if is_decreasing(a_n, interval): dirich = _dirichlet_test(b_n) if dirich is not None: return dirich bc_test = _bounded_convergent_test(a_n, b_n) if bc_test is not None: return bc_test _sym = self.limits[0][0] sequence_term = sequence_term.xreplace({sym: _sym}) raise NotImplementedError("The algorithm to find the Sum convergence of %s " "is not yet implemented" % (sequence_term)) def is_absolutely_convergent(self): """ Checks for the absolute convergence of an infinite series. Same as checking convergence of absolute value of sequence_term of an infinite series. References ========== .. [1] https://en.wikipedia.org/wiki/Absolute_convergence Examples ======== >>> from sympy import Sum, Symbol, sin, oo >>> n = Symbol('n', integer=True) >>> Sum((-1)**n, (n, 1, oo)).is_absolutely_convergent() False >>> Sum((-1)**n/n**2, (n, 1, oo)).is_absolutely_convergent() True See Also ======== Sum.is_convergent() """ return Sum(abs(self.function), self.limits).is_convergent() def euler_maclaurin(self, m=0, n=0, eps=0, eval_integral=True): """ Return an Euler-Maclaurin approximation of self, where m is the number of leading terms to sum directly and n is the number of terms in the tail. With m = n = 0, this is simply the corresponding integral plus a first-order endpoint correction. Returns (s, e) where s is the Euler-Maclaurin approximation and e is the estimated error (taken to be the magnitude of the first omitted term in the tail): >>> from sympy.abc import k, a, b >>> from sympy import Sum >>> Sum(1/k, (k, 2, 5)).doit().evalf() 1.28333333333333 >>> s, e = Sum(1/k, (k, 2, 5)).euler_maclaurin() >>> s -log(2) + 7/20 + log(5) >>> from sympy import sstr >>> print(sstr((s.evalf(), e.evalf()), full_prec=True)) (1.26629073187415, 0.0175000000000000) The endpoints may be symbolic: >>> s, e = Sum(1/k, (k, a, b)).euler_maclaurin() >>> s -log(a) + log(b) + 1/(2*b) + 1/(2*a) >>> e Abs(1/(12*b**2) - 1/(12*a**2)) If the function is a polynomial of degree at most 2n+1, the Euler-Maclaurin formula becomes exact (and e = 0 is returned): >>> Sum(k, (k, 2, b)).euler_maclaurin() (b**2/2 + b/2 - 1, 0) >>> Sum(k, (k, 2, b)).doit() b**2/2 + b/2 - 1 With a nonzero eps specified, the summation is ended as soon as the remainder term is less than the epsilon. """ from sympy.functions import bernoulli, factorial from sympy.integrals import Integral m = int(m) n = int(n) f = self.function if len(self.limits) != 1: raise ValueError("More than 1 limit") i, a, b = self.limits[0] if (a > b) == True: if a - b == 1: return S.Zero, S.Zero a, b = b + 1, a - 1 f = -f s = S.Zero if m: if b.is_Integer and a.is_Integer: m = min(m, b - a + 1) if not eps or f.is_polynomial(i): for k in range(m): s += f.subs(i, a + k) else: term = f.subs(i, a) if term: test = abs(term.evalf(3)) < eps if test == True: return s, abs(term) elif not (test == False): # a symbolic Relational class, can't go further return term, S.Zero s += term for k in range(1, m): term = f.subs(i, a + k) if abs(term.evalf(3)) < eps and term != 0: return s, abs(term) s += term if b - a + 1 == m: return s, S.Zero a += m x = Dummy('x') I = Integral(f.subs(i, x), (x, a, b)) if eval_integral: I = I.doit() s += I def fpoint(expr): if b is S.Infinity: return expr.subs(i, a), 0 return expr.subs(i, a), expr.subs(i, b) fa, fb = fpoint(f) iterm = (fa + fb)/2 g = f.diff(i) for k in range(1, n + 2): ga, gb = fpoint(g) term = bernoulli(2*k)/factorial(2*k)*(gb - ga) if (eps and term and abs(term.evalf(3)) < eps) or (k > n): break s += term g = g.diff(i, 2, simplify=False) return s + iterm, abs(term) def reverse_order(self, *indices): """ Reverse the order of a limit in a Sum. Usage ===== ``reverse_order(self, *indices)`` reverses some limits in the expression ``self`` which can be either a ``Sum`` or a ``Product``. The selectors in the argument ``indices`` specify some indices whose limits get reversed. These selectors are either variable names or numerical indices counted starting from the inner-most limit tuple. Examples ======== >>> from sympy import Sum >>> from sympy.abc import x, y, a, b, c, d >>> Sum(x, (x, 0, 3)).reverse_order(x) Sum(-x, (x, 4, -1)) >>> Sum(x*y, (x, 1, 5), (y, 0, 6)).reverse_order(x, y) Sum(x*y, (x, 6, 0), (y, 7, -1)) >>> Sum(x, (x, a, b)).reverse_order(x) Sum(-x, (x, b + 1, a - 1)) >>> Sum(x, (x, a, b)).reverse_order(0) Sum(-x, (x, b + 1, a - 1)) While one should prefer variable names when specifying which limits to reverse, the index counting notation comes in handy in case there are several symbols with the same name. >>> S = Sum(x**2, (x, a, b), (x, c, d)) >>> S Sum(x**2, (x, a, b), (x, c, d)) >>> S0 = S.reverse_order(0) >>> S0 Sum(-x**2, (x, b + 1, a - 1), (x, c, d)) >>> S1 = S0.reverse_order(1) >>> S1 Sum(x**2, (x, b + 1, a - 1), (x, d + 1, c - 1)) Of course we can mix both notations: >>> Sum(x*y, (x, a, b), (y, 2, 5)).reverse_order(x, 1) Sum(x*y, (x, b + 1, a - 1), (y, 6, 1)) >>> Sum(x*y, (x, a, b), (y, 2, 5)).reverse_order(y, x) Sum(x*y, (x, b + 1, a - 1), (y, 6, 1)) See Also ======== index, reorder_limit, reorder References ========== .. [1] Michael Karr, "Summation in Finite Terms", Journal of the ACM, Volume 28 Issue 2, April 1981, Pages 305-350 http://dl.acm.org/citation.cfm?doid=322248.322255 """ l_indices = list(indices) for i, indx in enumerate(l_indices): if not isinstance(indx, int): l_indices[i] = self.index(indx) e = 1 limits = [] for i, limit in enumerate(self.limits): l = limit if i in l_indices: e = -e l = (limit[0], limit[2] + 1, limit[1] - 1) limits.append(l) return Sum(e * self.function, *limits) def summation(f, *symbols, **kwargs): r""" Compute the summation of f with respect to symbols. The notation for symbols is similar to the notation used in Integral. summation(f, (i, a, b)) computes the sum of f with respect to i from a to b, i.e., :: b ____ \ ` summation(f, (i, a, b)) = ) f /___, i = a If it cannot compute the sum, it returns an unevaluated Sum object. Repeated sums can be computed by introducing additional symbols tuples:: >>> from sympy import summation, oo, symbols, log >>> i, n, m = symbols('i n m', integer=True) >>> summation(2*i - 1, (i, 1, n)) n**2 >>> summation(1/2**i, (i, 0, oo)) 2 >>> summation(1/log(n)**n, (n, 2, oo)) Sum(log(n)**(-n), (n, 2, oo)) >>> summation(i, (i, 0, n), (n, 0, m)) m**3/6 + m**2/2 + m/3 >>> from sympy.abc import x >>> from sympy import factorial >>> summation(x**n/factorial(n), (n, 0, oo)) exp(x) See Also ======== Sum Product, product """ return Sum(f, *symbols, **kwargs).doit(deep=False) def telescopic_direct(L, R, n, limits): """Returns the direct summation of the terms of a telescopic sum L is the term with lower index R is the term with higher index n difference between the indexes of L and R For example: >>> from sympy.concrete.summations import telescopic_direct >>> from sympy.abc import k, a, b >>> telescopic_direct(1/k, -1/(k+2), 2, (k, a, b)) -1/(b + 2) - 1/(b + 1) + 1/(a + 1) + 1/a """ (i, a, b) = limits s = 0 for m in range(n): s += L.subs(i, a + m) + R.subs(i, b - m) return s def telescopic(L, R, limits): '''Tries to perform the summation using the telescopic property return None if not possible ''' (i, a, b) = limits if L.is_Add or R.is_Add: return None # We want to solve(L.subs(i, i + m) + R, m) # First we try a simple match since this does things that # solve doesn't do, e.g. solve(f(k+m)-f(k), m) fails k = Wild("k") sol = (-R).match(L.subs(i, i + k)) s = None if sol and k in sol: s = sol[k] if not (s.is_Integer and L.subs(i, i + s) == -R): # sometimes match fail(f(x+2).match(-f(x+k))->{k: -2 - 2x})) s = None # But there are things that match doesn't do that solve # can do, e.g. determine that 1/(x + m) = 1/(1 - x) when m = 1 if s is None: m = Dummy('m') try: sol = solve(L.subs(i, i + m) + R, m) or [] except NotImplementedError: return None sol = [si for si in sol if si.is_Integer and (L.subs(i, i + si) + R).expand().is_zero] if len(sol) != 1: return None s = sol[0] if s < 0: return telescopic_direct(R, L, abs(s), (i, a, b)) elif s > 0: return telescopic_direct(L, R, s, (i, a, b)) def eval_sum(f, limits): from sympy.concrete.delta import deltasummation, _has_simple_delta from sympy.functions import KroneckerDelta (i, a, b) = limits if f is S.Zero: return S.Zero if i not in f.free_symbols: return f*(b - a + 1) if a == b: return f.subs(i, a) if isinstance(f, Piecewise): if not any(i in arg.args[1].free_symbols for arg in f.args): # Piecewise conditions do not depend on the dummy summation variable, # therefore we can fold: Sum(Piecewise((e, c), ...), limits) # --> Piecewise((Sum(e, limits), c), ...) newargs = [] for arg in f.args: newexpr = eval_sum(arg.expr, limits) if newexpr is None: return None newargs.append((newexpr, arg.cond)) return f.func(*newargs) if f.has(KroneckerDelta) and _has_simple_delta(f, limits[0]): return deltasummation(f, limits) dif = b - a definite = dif.is_Integer # Doing it directly may be faster if there are very few terms. if definite and (dif < 100): return eval_sum_direct(f, (i, a, b)) if isinstance(f, Piecewise): return None # Try to do it symbolically. Even when the number of terms is known, # this can save time when b-a is big. # We should try to transform to partial fractions value = eval_sum_symbolic(f.expand(), (i, a, b)) if value is not None: return value # Do it directly if definite: return eval_sum_direct(f, (i, a, b)) def eval_sum_direct(expr, limits): from sympy.core import Add (i, a, b) = limits dif = b - a return Add(*[expr.subs(i, a + j) for j in range(dif + 1)]) def eval_sum_symbolic(f, limits): from sympy.functions import harmonic, bernoulli f_orig = f (i, a, b) = limits if not f.has(i): return f*(b - a + 1) # Linearity if f.is_Mul: L, R = f.as_two_terms() if not L.has(i): sR = eval_sum_symbolic(R, (i, a, b)) if sR: return L*sR if not R.has(i): sL = eval_sum_symbolic(L, (i, a, b)) if sL: return R*sL try: f = apart(f, i) # see if it becomes an Add except PolynomialError: pass if f.is_Add: L, R = f.as_two_terms() lrsum = telescopic(L, R, (i, a, b)) if lrsum: return lrsum lsum = eval_sum_symbolic(L, (i, a, b)) rsum = eval_sum_symbolic(R, (i, a, b)) if None not in (lsum, rsum): r = lsum + rsum if not r is S.NaN: return r # Polynomial terms with Faulhaber's formula n = Wild('n') result = f.match(i**n) if result is not None: n = result[n] if n.is_Integer: if n >= 0: if (b is S.Infinity and not a is S.NegativeInfinity) or \ (a is S.NegativeInfinity and not b is S.Infinity): return S.Infinity return ((bernoulli(n + 1, b + 1) - bernoulli(n + 1, a))/(n + 1)).expand() elif a.is_Integer and a >= 1: if n == -1: return harmonic(b) - harmonic(a - 1) else: return harmonic(b, abs(n)) - harmonic(a - 1, abs(n)) if not (a.has(S.Infinity, S.NegativeInfinity) or b.has(S.Infinity, S.NegativeInfinity)): # Geometric terms c1 = Wild('c1', exclude=[i]) c2 = Wild('c2', exclude=[i]) c3 = Wild('c3', exclude=[i]) wexp = Wild('wexp') # Here we first attempt powsimp on f for easier matching with the # exponential pattern, and attempt expansion on the exponent for easier # matching with the linear pattern. e = f.powsimp().match(c1 ** wexp) if e is not None: e_exp = e.pop(wexp).expand().match(c2*i + c3) if e_exp is not None: e.update(e_exp) if e is not None: p = (c1**c3).subs(e) q = (c1**c2).subs(e) r = p*(q**a - q**(b + 1))/(1 - q) l = p*(b - a + 1) return Piecewise((l, Eq(q, S.One)), (r, True)) r = gosper_sum(f, (i, a, b)) if isinstance(r, (Mul,Add)): from sympy import ordered, Tuple non_limit = r.free_symbols - Tuple(*limits[1:]).free_symbols den = denom(together(r)) den_sym = non_limit & den.free_symbols args = [] for v in ordered(den_sym): try: s = solve(den, v) m = Eq(v, s[0]) if s else S.false if m != False: args.append((Sum(f_orig.subs(*m.args), limits).doit(), m)) break except NotImplementedError: continue args.append((r, True)) return Piecewise(*args) if not r in (None, S.NaN): return r h = eval_sum_hyper(f_orig, (i, a, b)) if h is not None: return h factored = f_orig.factor() if factored != f_orig: return eval_sum_symbolic(factored, (i, a, b)) def _eval_sum_hyper(f, i, a): """ Returns (res, cond). Sums from a to oo. """ from sympy.functions import hyper from sympy.simplify import hyperexpand, hypersimp, fraction, simplify from sympy.polys.polytools import Poly, factor from sympy.core.numbers import Float if a != 0: return _eval_sum_hyper(f.subs(i, i + a), i, 0) if f.subs(i, 0) == 0: if simplify(f.subs(i, Dummy('i', integer=True, positive=True))) == 0: return S(0), True return _eval_sum_hyper(f.subs(i, i + 1), i, 0) hs = hypersimp(f, i) if hs is None: return None if isinstance(hs, Float): from sympy.simplify.simplify import nsimplify hs = nsimplify(hs) numer, denom = fraction(factor(hs)) top, topl = numer.as_coeff_mul(i) bot, botl = denom.as_coeff_mul(i) ab = [top, bot] factors = [topl, botl] params = [[], []] for k in range(2): for fac in factors[k]: mul = 1 if fac.is_Pow: mul = fac.exp fac = fac.base if not mul.is_Integer: return None p = Poly(fac, i) if p.degree() != 1: return None m, n = p.all_coeffs() ab[k] *= m**mul params[k] += [n/m]*mul # Add "1" to numerator parameters, to account for implicit n! in # hypergeometric series. ap = params[0] + [1] bq = params[1] x = ab[0]/ab[1] h = hyper(ap, bq, x) return f.subs(i, 0)*hyperexpand(h), h.convergence_statement def eval_sum_hyper(f, i_a_b): from sympy.logic.boolalg import And i, a, b = i_a_b if (b - a).is_Integer: # We are never going to do better than doing the sum in the obvious way return None old_sum = Sum(f, (i, a, b)) if b != S.Infinity: if a == S.NegativeInfinity: res = _eval_sum_hyper(f.subs(i, -i), i, -b) if res is not None: return Piecewise(res, (old_sum, True)) else: res1 = _eval_sum_hyper(f, i, a) res2 = _eval_sum_hyper(f, i, b + 1) if res1 is None or res2 is None: return None (res1, cond1), (res2, cond2) = res1, res2 cond = And(cond1, cond2) if cond == False: return None return Piecewise((res1 - res2, cond), (old_sum, True)) if a == S.NegativeInfinity: res1 = _eval_sum_hyper(f.subs(i, -i), i, 1) res2 = _eval_sum_hyper(f, i, 0) if res1 is None or res2 is None: return None res1, cond1 = res1 res2, cond2 = res2 cond = And(cond1, cond2) if cond == False: return None return Piecewise((res1 + res2, cond), (old_sum, True)) # Now b == oo, a != -oo res = _eval_sum_hyper(f, i, a) if res is not None: r, c = res if c == False: if r.is_number: f = f.subs(i, Dummy('i', integer=True, positive=True) + a) if f.is_positive or f.is_zero: return S.Infinity elif f.is_negative: return S.NegativeInfinity return None return Piecewise(res, (old_sum, True))

008a547620a0adc51a337d124bb92e8cd53c67e4ec331ee5bdf0a8786894ca54

""" Expand Hypergeometric (and Meijer G) functions into named special functions. The algorithm for doing this uses a collection of lookup tables of hypergeometric functions, and various of their properties, to expand many hypergeometric functions in terms of special functions. It is based on the following paper: Kelly B. Roach. Meijer G Function Representations. In: Proceedings of the 1997 International Symposium on Symbolic and Algebraic Computation, pages 205-211, New York, 1997. ACM. It is described in great(er) detail in the Sphinx documentation. """ # SUMMARY OF EXTENSIONS FOR MEIJER G FUNCTIONS # # o z**rho G(ap, bq; z) = G(ap + rho, bq + rho; z) # # o denote z*d/dz by D # # o It is helpful to keep in mind that ap and bq play essentially symmetric # roles: G(1/z) has slightly altered parameters, with ap and bq interchanged. # # o There are four shift operators: # A_J = b_J - D, J = 1, ..., n # B_J = 1 - a_j + D, J = 1, ..., m # C_J = -b_J + D, J = m+1, ..., q # D_J = a_J - 1 - D, J = n+1, ..., p # # A_J, C_J increment b_J # B_J, D_J decrement a_J # # o The corresponding four inverse-shift operators are defined if there # is no cancellation. Thus e.g. an index a_J (upper or lower) can be # incremented if a_J != b_i for i = 1, ..., q. # # o Order reduction: if b_j - a_i is a non-negative integer, where # j <= m and i > n, the corresponding quotient of gamma functions reduces # to a polynomial. Hence the G function can be expressed using a G-function # of lower order. # Similarly if j > m and i <= n. # # Secondly, there are paired index theorems [Adamchik, The evaluation of # integrals of Bessel functions via G-function identities]. Suppose there # are three parameters a, b, c, where a is an a_i, i <= n, b is a b_j, # j <= m and c is a denominator parameter (i.e. a_i, i > n or b_j, j > m). # Suppose further all three differ by integers. # Then the order can be reduced. # TODO work this out in detail. # # o An index quadruple is called suitable if its order cannot be reduced. # If there exists a sequence of shift operators transforming one index # quadruple into another, we say one is reachable from the other. # # o Deciding if one index quadruple is reachable from another is tricky. For # this reason, we use hand-built routines to match and instantiate formulas. # from __future__ import print_function, division from collections import defaultdict from itertools import product from sympy import SYMPY_DEBUG from sympy.core import (S, Dummy, symbols, sympify, Tuple, expand, I, pi, Mul, EulerGamma, oo, zoo, expand_func, Add, nan, Expr) from sympy.core.compatibility import default_sort_key, range from sympy.core.mod import Mod from sympy.functions import (exp, sqrt, root, log, lowergamma, cos, besseli, gamma, uppergamma, expint, erf, sin, besselj, Ei, Ci, Si, Shi, sinh, cosh, Chi, fresnels, fresnelc, polar_lift, exp_polar, floor, ceiling, rf, factorial, lerchphi, Piecewise, re, elliptic_k, elliptic_e) from sympy.functions.elementary.complexes import polarify, unpolarify from sympy.functions.special.hyper import (hyper, HyperRep_atanh, HyperRep_power1, HyperRep_power2, HyperRep_log1, HyperRep_asin1, HyperRep_asin2, HyperRep_sqrts1, HyperRep_sqrts2, HyperRep_log2, HyperRep_cosasin, HyperRep_sinasin, meijerg) from sympy.polys import poly, Poly from sympy.series import residue from sympy.simplify import simplify from sympy.simplify.powsimp import powdenest from sympy.utilities.iterables import sift # function to define "buckets" def _mod1(x): # TODO see if this can work as Mod(x, 1); this will require # different handling of the "buckets" since these need to # be sorted and that fails when there is a mixture of # integers and expressions with parameters. With the current # Mod behavior, Mod(k, 1) == Mod(1, 1) == 0 if k is an integer. # Although the sorting can be done with Basic.compare, this may # still require different handling of the sorted buckets. if x.is_Number: return Mod(x, 1) c, x = x.as_coeff_Add() return Mod(c, 1) + x # leave add formulae at the top for easy reference def add_formulae(formulae): """ Create our knowledge base. """ from sympy.matrices import Matrix a, b, c, z = symbols('a b c, z', cls=Dummy) def add(ap, bq, res): func = Hyper_Function(ap, bq) formulae.append(Formula(func, z, res, (a, b, c))) def addb(ap, bq, B, C, M): func = Hyper_Function(ap, bq) formulae.append(Formula(func, z, None, (a, b, c), B, C, M)) # Luke, Y. L. (1969), The Special Functions and Their Approximations, # Volume 1, section 6.2 # 0F0 add((), (), exp(z)) # 1F0 add((a, ), (), HyperRep_power1(-a, z)) # 2F1 addb((a, a - S.Half), (2*a, ), Matrix([HyperRep_power2(a, z), HyperRep_power2(a + S(1)/2, z)/2]), Matrix([[1, 0]]), Matrix([[(a - S.Half)*z/(1 - z), (S.Half - a)*z/(1 - z)], [a/(1 - z), a*(z - 2)/(1 - z)]])) addb((1, 1), (2, ), Matrix([HyperRep_log1(z), 1]), Matrix([[-1/z, 0]]), Matrix([[0, z/(z - 1)], [0, 0]])) addb((S.Half, 1), (S('3/2'), ), Matrix([HyperRep_atanh(z), 1]), Matrix([[1, 0]]), Matrix([[-S(1)/2, 1/(1 - z)/2], [0, 0]])) addb((S.Half, S.Half), (S('3/2'), ), Matrix([HyperRep_asin1(z), HyperRep_power1(-S(1)/2, z)]), Matrix([[1, 0]]), Matrix([[-S(1)/2, S(1)/2], [0, z/(1 - z)/2]])) addb((a, S.Half + a), (S.Half, ), Matrix([HyperRep_sqrts1(-a, z), -HyperRep_sqrts2(-a - S(1)/2, z)]), Matrix([[1, 0]]), Matrix([[0, -a], [z*(-2*a - 1)/2/(1 - z), S.Half - z*(-2*a - 1)/(1 - z)]])) # A. P. Prudnikov, Yu. A. Brychkov and O. I. Marichev (1990). # Integrals and Series: More Special Functions, Vol. 3,. # Gordon and Breach Science Publisher addb([a, -a], [S.Half], Matrix([HyperRep_cosasin(a, z), HyperRep_sinasin(a, z)]), Matrix([[1, 0]]), Matrix([[0, -a], [a*z/(1 - z), 1/(1 - z)/2]])) addb([1, 1], [3*S.Half], Matrix([HyperRep_asin2(z), 1]), Matrix([[1, 0]]), Matrix([[(z - S.Half)/(1 - z), 1/(1 - z)/2], [0, 0]])) # Complete elliptic integrals K(z) and E(z), both a 2F1 function addb([S.Half, S.Half], [S.One], Matrix([elliptic_k(z), elliptic_e(z)]), Matrix([[2/pi, 0]]), Matrix([[-S.Half, -1/(2*z-2)], [-S.Half, S.Half]])) addb([-S.Half, S.Half], [S.One], Matrix([elliptic_k(z), elliptic_e(z)]), Matrix([[0, 2/pi]]), Matrix([[-S.Half, -1/(2*z-2)], [-S.Half, S.Half]])) # 3F2 addb([-S.Half, 1, 1], [S.Half, 2], Matrix([z*HyperRep_atanh(z), HyperRep_log1(z), 1]), Matrix([[-S(2)/3, -S(1)/(3*z), S(2)/3]]), Matrix([[S(1)/2, 0, z/(1 - z)/2], [0, 0, z/(z - 1)], [0, 0, 0]])) # actually the formula for 3/2 is much nicer ... addb([-S.Half, 1, 1], [2, 2], Matrix([HyperRep_power1(S(1)/2, z), HyperRep_log2(z), 1]), Matrix([[S(4)/9 - 16/(9*z), 4/(3*z), 16/(9*z)]]), Matrix([[z/2/(z - 1), 0, 0], [1/(2*(z - 1)), 0, S.Half], [0, 0, 0]])) # 1F1 addb([1], [b], Matrix([z**(1 - b) * exp(z) * lowergamma(b - 1, z), 1]), Matrix([[b - 1, 0]]), Matrix([[1 - b + z, 1], [0, 0]])) addb([a], [2*a], Matrix([z**(S.Half - a)*exp(z/2)*besseli(a - S.Half, z/2) * gamma(a + S.Half)/4**(S.Half - a), z**(S.Half - a)*exp(z/2)*besseli(a + S.Half, z/2) * gamma(a + S.Half)/4**(S.Half - a)]), Matrix([[1, 0]]), Matrix([[z/2, z/2], [z/2, (z/2 - 2*a)]])) mz = polar_lift(-1)*z addb([a], [a + 1], Matrix([mz**(-a)*a*lowergamma(a, mz), a*exp(z)]), Matrix([[1, 0]]), Matrix([[-a, 1], [0, z]])) # This one is redundant. add([-S.Half], [S.Half], exp(z) - sqrt(pi*z)*(-I)*erf(I*sqrt(z))) # Added to get nice results for Laplace transform of Fresnel functions # http://functions.wolfram.com/07.22.03.6437.01 # Basic rule #add([1], [S(3)/4, S(5)/4], # sqrt(pi) * (cos(2*sqrt(polar_lift(-1)*z))*fresnelc(2*root(polar_lift(-1)*z,4)/sqrt(pi)) + # sin(2*sqrt(polar_lift(-1)*z))*fresnels(2*root(polar_lift(-1)*z,4)/sqrt(pi))) # / (2*root(polar_lift(-1)*z,4))) # Manually tuned rule addb([1], [S(3)/4, S(5)/4], Matrix([ sqrt(pi)*(I*sinh(2*sqrt(z))*fresnels(2*root(z, 4)*exp(I*pi/4)/sqrt(pi)) + cosh(2*sqrt(z))*fresnelc(2*root(z, 4)*exp(I*pi/4)/sqrt(pi))) * exp(-I*pi/4)/(2*root(z, 4)), sqrt(pi)*root(z, 4)*(sinh(2*sqrt(z))*fresnelc(2*root(z, 4)*exp(I*pi/4)/sqrt(pi)) + I*cosh(2*sqrt(z))*fresnels(2*root(z, 4)*exp(I*pi/4)/sqrt(pi))) *exp(-I*pi/4)/2, 1 ]), Matrix([[1, 0, 0]]), Matrix([[-S(1)/4, 1, S(1)/4], [ z, S(1)/4, 0 ], [ 0, 0, 0 ]])) # 2F2 addb([S.Half, a], [S(3)/2, a + 1], Matrix([a/(2*a - 1)*(-I)*sqrt(pi/z)*erf(I*sqrt(z)), a/(2*a - 1)*(polar_lift(-1)*z)**(-a)* lowergamma(a, polar_lift(-1)*z), a/(2*a - 1)*exp(z)]), Matrix([[1, -1, 0]]), Matrix([[-S.Half, 0, 1], [0, -a, 1], [0, 0, z]])) # We make a "basis" of four functions instead of three, and give EulerGamma # an extra slot (it could just be a coefficient to 1). The advantage is # that this way Polys will not see multivariate polynomials (it treats # EulerGamma as an indeterminate), which is *way* faster. addb([1, 1], [2, 2], Matrix([Ei(z) - log(z), exp(z), 1, EulerGamma]), Matrix([[1/z, 0, 0, -1/z]]), Matrix([[0, 1, -1, 0], [0, z, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0]])) # 0F1 add((), (S.Half, ), cosh(2*sqrt(z))) addb([], [b], Matrix([gamma(b)*z**((1 - b)/2)*besseli(b - 1, 2*sqrt(z)), gamma(b)*z**(1 - b/2)*besseli(b, 2*sqrt(z))]), Matrix([[1, 0]]), Matrix([[0, 1], [z, (1 - b)]])) # 0F3 x = 4*z**(S(1)/4) def fp(a, z): return besseli(a, x) + besselj(a, x) def fm(a, z): return besseli(a, x) - besselj(a, x) # TODO branching addb([], [S.Half, a, a + S.Half], Matrix([fp(2*a - 1, z), fm(2*a, z)*z**(S(1)/4), fm(2*a - 1, z)*sqrt(z), fp(2*a, z)*z**(S(3)/4)]) * 2**(-2*a)*gamma(2*a)*z**((1 - 2*a)/4), Matrix([[1, 0, 0, 0]]), Matrix([[0, 1, 0, 0], [0, S(1)/2 - a, 1, 0], [0, 0, S(1)/2, 1], [z, 0, 0, 1 - a]])) x = 2*(4*z)**(S(1)/4)*exp_polar(I*pi/4) addb([], [a, a + S.Half, 2*a], (2*sqrt(polar_lift(-1)*z))**(1 - 2*a)*gamma(2*a)**2 * Matrix([besselj(2*a - 1, x)*besseli(2*a - 1, x), x*(besseli(2*a, x)*besselj(2*a - 1, x) - besseli(2*a - 1, x)*besselj(2*a, x)), x**2*besseli(2*a, x)*besselj(2*a, x), x**3*(besseli(2*a, x)*besselj(2*a - 1, x) + besseli(2*a - 1, x)*besselj(2*a, x))]), Matrix([[1, 0, 0, 0]]), Matrix([[0, S(1)/4, 0, 0], [0, (1 - 2*a)/2, -S(1)/2, 0], [0, 0, 1 - 2*a, S(1)/4], [-32*z, 0, 0, 1 - a]])) # 1F2 addb([a], [a - S.Half, 2*a], Matrix([z**(S.Half - a)*besseli(a - S.Half, sqrt(z))**2, z**(1 - a)*besseli(a - S.Half, sqrt(z)) *besseli(a - S(3)/2, sqrt(z)), z**(S(3)/2 - a)*besseli(a - S(3)/2, sqrt(z))**2]), Matrix([[-gamma(a + S.Half)**2/4**(S.Half - a), 2*gamma(a - S.Half)*gamma(a + S.Half)/4**(1 - a), 0]]), Matrix([[1 - 2*a, 1, 0], [z/2, S.Half - a, S.Half], [0, z, 0]])) addb([S.Half], [b, 2 - b], pi*(1 - b)/sin(pi*b)* Matrix([besseli(1 - b, sqrt(z))*besseli(b - 1, sqrt(z)), sqrt(z)*(besseli(-b, sqrt(z))*besseli(b - 1, sqrt(z)) + besseli(1 - b, sqrt(z))*besseli(b, sqrt(z))), besseli(-b, sqrt(z))*besseli(b, sqrt(z))]), Matrix([[1, 0, 0]]), Matrix([[b - 1, S(1)/2, 0], [z, 0, z], [0, S(1)/2, -b]])) addb([S(1)/2], [S(3)/2, S(3)/2], Matrix([Shi(2*sqrt(z))/2/sqrt(z), sinh(2*sqrt(z))/2/sqrt(z), cosh(2*sqrt(z))]), Matrix([[1, 0, 0]]), Matrix([[-S.Half, S.Half, 0], [0, -S.Half, S.Half], [0, 2*z, 0]])) # FresnelS # Basic rule #add([S(3)/4], [S(3)/2,S(7)/4], 6*fresnels( exp(pi*I/4)*root(z,4)*2/sqrt(pi) ) / ( pi * (exp(pi*I/4)*root(z,4)*2/sqrt(pi))**3 ) ) # Manually tuned rule addb([S(3)/4], [S(3)/2, S(7)/4], Matrix( [ fresnels( exp( pi*I/4)*root( z, 4)*2/sqrt( pi) ) / ( pi * (exp(pi*I/4)*root(z, 4)*2/sqrt(pi))**3 ), sinh(2*sqrt(z))/sqrt(z), cosh(2*sqrt(z)) ]), Matrix([[6, 0, 0]]), Matrix([[-S(3)/4, S(1)/16, 0], [ 0, -S(1)/2, 1], [ 0, z, 0]])) # FresnelC # Basic rule #add([S(1)/4], [S(1)/2,S(5)/4], fresnelc( exp(pi*I/4)*root(z,4)*2/sqrt(pi) ) / ( exp(pi*I/4)*root(z,4)*2/sqrt(pi) ) ) # Manually tuned rule addb([S(1)/4], [S(1)/2, S(5)/4], Matrix( [ sqrt( pi)*exp( -I*pi/4)*fresnelc( 2*root(z, 4)*exp(I*pi/4)/sqrt(pi))/(2*root(z, 4)), cosh(2*sqrt(z)), sinh(2*sqrt(z))*sqrt(z) ]), Matrix([[1, 0, 0]]), Matrix([[-S(1)/4, S(1)/4, 0 ], [ 0, 0, 1 ], [ 0, z, S(1)/2]])) # 2F3 # XXX with this five-parameter formula is pretty slow with the current # Formula.find_instantiations (creates 2!*3!*3**(2+3) ~ 3000 # instantiations ... But it's not too bad. addb([a, a + S.Half], [2*a, b, 2*a - b + 1], gamma(b)*gamma(2*a - b + 1) * (sqrt(z)/2)**(1 - 2*a) * Matrix([besseli(b - 1, sqrt(z))*besseli(2*a - b, sqrt(z)), sqrt(z)*besseli(b, sqrt(z))*besseli(2*a - b, sqrt(z)), sqrt(z)*besseli(b - 1, sqrt(z))*besseli(2*a - b + 1, sqrt(z)), besseli(b, sqrt(z))*besseli(2*a - b + 1, sqrt(z))]), Matrix([[1, 0, 0, 0]]), Matrix([[0, S(1)/2, S(1)/2, 0], [z/2, 1 - b, 0, z/2], [z/2, 0, b - 2*a, z/2], [0, S(1)/2, S(1)/2, -2*a]])) # (C/f above comment about eulergamma in the basis). addb([1, 1], [2, 2, S(3)/2], Matrix([Chi(2*sqrt(z)) - log(2*sqrt(z)), cosh(2*sqrt(z)), sqrt(z)*sinh(2*sqrt(z)), 1, EulerGamma]), Matrix([[1/z, 0, 0, 0, -1/z]]), Matrix([[0, S(1)/2, 0, -S(1)/2, 0], [0, 0, 1, 0, 0], [0, z, S(1)/2, 0, 0], [0, 0, 0, 0, 0], [0, 0, 0, 0, 0]])) # 3F3 # This is rule: http://functions.wolfram.com/07.31.03.0134.01 # Initial reason to add it was a nice solution for # integrate(erf(a*z)/z**2, z) and same for erfc and erfi. # Basic rule # add([1, 1, a], [2, 2, a+1], (a/(z*(a-1)**2)) * # (1 - (-z)**(1-a) * (gamma(a) - uppergamma(a,-z)) # - (a-1) * (EulerGamma + uppergamma(0,-z) + log(-z)) # - exp(z))) # Manually tuned rule addb([1, 1, a], [2, 2, a+1], Matrix([a*(log(-z) + expint(1, -z) + EulerGamma)/(z*(a**2 - 2*a + 1)), a*(-z)**(-a)*(gamma(a) - uppergamma(a, -z))/(a - 1)**2, a*exp(z)/(a**2 - 2*a + 1), a/(z*(a**2 - 2*a + 1))]), Matrix([[1-a, 1, -1/z, 1]]), Matrix([[-1,0,-1/z,1], [0,-a,1,0], [0,0,z,0], [0,0,0,-1]])) def add_meijerg_formulae(formulae): from sympy.matrices import Matrix a, b, c, z = list(map(Dummy, 'abcz')) rho = Dummy('rho') def add(an, ap, bm, bq, B, C, M, matcher): formulae.append(MeijerFormula(an, ap, bm, bq, z, [a, b, c, rho], B, C, M, matcher)) def detect_uppergamma(func): x = func.an[0] y, z = func.bm swapped = False if not _mod1((x - y).simplify()): swapped = True (y, z) = (z, y) if _mod1((x - z).simplify()) or x - z > 0: return None l = [y, x] if swapped: l = [x, y] return {rho: y, a: x - y}, G_Function([x], [], l, []) add([a + rho], [], [rho, a + rho], [], Matrix([gamma(1 - a)*z**rho*exp(z)*uppergamma(a, z), gamma(1 - a)*z**(a + rho)]), Matrix([[1, 0]]), Matrix([[rho + z, -1], [0, a + rho]]), detect_uppergamma) def detect_3113(func): """http://functions.wolfram.com/07.34.03.0984.01""" x = func.an[0] u, v, w = func.bm if _mod1((u - v).simplify()) == 0: if _mod1((v - w).simplify()) == 0: return sig = (S(1)/2, S(1)/2, S(0)) x1, x2, y = u, v, w else: if _mod1((x - u).simplify()) == 0: sig = (S(1)/2, S(0), S(1)/2) x1, y, x2 = u, v, w else: sig = (S(0), S(1)/2, S(1)/2) y, x1, x2 = u, v, w if (_mod1((x - x1).simplify()) != 0 or _mod1((x - x2).simplify()) != 0 or _mod1((x - y).simplify()) != S(1)/2 or x - x1 > 0 or x - x2 > 0): return return {a: x}, G_Function([x], [], [x - S(1)/2 + t for t in sig], []) s = sin(2*sqrt(z)) c_ = cos(2*sqrt(z)) S_ = Si(2*sqrt(z)) - pi/2 C = Ci(2*sqrt(z)) add([a], [], [a, a, a - S(1)/2], [], Matrix([sqrt(pi)*z**(a - S(1)/2)*(c_*S_ - s*C), sqrt(pi)*z**a*(s*S_ + c_*C), sqrt(pi)*z**a]), Matrix([[-2, 0, 0]]), Matrix([[a - S(1)/2, -1, 0], [z, a, S(1)/2], [0, 0, a]]), detect_3113) def make_simp(z): """ Create a function that simplifies rational functions in ``z``. """ def simp(expr): """ Efficiently simplify the rational function ``expr``. """ numer, denom = expr.as_numer_denom() numer = numer.expand() # denom = denom.expand() # is this needed? c, numer, denom = poly(numer, z).cancel(poly(denom, z)) return c * numer.as_expr() / denom.as_expr() return simp def debug(*args): if SYMPY_DEBUG: for a in args: print(a, end="") print() class Hyper_Function(Expr): """ A generalized hypergeometric function. """ def __new__(cls, ap, bq): obj = super(Hyper_Function, cls).__new__(cls) obj.ap = Tuple(*list(map(expand, ap))) obj.bq = Tuple(*list(map(expand, bq))) return obj @property def args(self): return (self.ap, self.bq) @property def sizes(self): return (len(self.ap), len(self.bq)) @property def gamma(self): """ Number of upper parameters that are negative integers This is a transformation invariant. """ return sum(bool(x.is_integer and x.is_negative) for x in self.ap) def _hashable_content(self): return super(Hyper_Function, self)._hashable_content() + (self.ap, self.bq) def __call__(self, arg): return hyper(self.ap, self.bq, arg) def build_invariants(self): """ Compute the invariant vector. The invariant vector is: (gamma, ((s1, n1), ..., (sk, nk)), ((t1, m1), ..., (tr, mr))) where gamma is the number of integer a < 0, s1 < ... < sk nl is the number of parameters a_i congruent to sl mod 1 t1 < ... < tr ml is the number of parameters b_i congruent to tl mod 1 If the index pair contains parameters, then this is not truly an invariant, since the parameters cannot be sorted uniquely mod1. Examples ======== >>> from sympy.simplify.hyperexpand import Hyper_Function >>> from sympy import S >>> ap = (S(1)/2, S(1)/3, S(-1)/2, -2) >>> bq = (1, 2) Here gamma = 1, k = 3, s1 = 0, s2 = 1/3, s3 = 1/2 n1 = 1, n2 = 1, n2 = 2 r = 1, t1 = 0 m1 = 2: >>> Hyper_Function(ap, bq).build_invariants() (1, ((0, 1), (1/3, 1), (1/2, 2)), ((0, 2),)) """ abuckets, bbuckets = sift(self.ap, _mod1), sift(self.bq, _mod1) def tr(bucket): bucket = list(bucket.items()) if not any(isinstance(x[0], Mod) for x in bucket): bucket.sort(key=lambda x: default_sort_key(x[0])) bucket = tuple([(mod, len(values)) for mod, values in bucket if values]) return bucket return (self.gamma, tr(abuckets), tr(bbuckets)) def difficulty(self, func): """ Estimate how many steps it takes to reach ``func`` from self. Return -1 if impossible. """ if self.gamma != func.gamma: return -1 oabuckets, obbuckets, abuckets, bbuckets = [sift(params, _mod1) for params in (self.ap, self.bq, func.ap, func.bq)] diff = 0 for bucket, obucket in [(abuckets, oabuckets), (bbuckets, obbuckets)]: for mod in set(list(bucket.keys()) + list(obucket.keys())): if (not mod in bucket) or (not mod in obucket) \ or len(bucket[mod]) != len(obucket[mod]): return -1 l1 = list(bucket[mod]) l2 = list(obucket[mod]) l1.sort() l2.sort() for i, j in zip(l1, l2): diff += abs(i - j) return diff def _is_suitable_origin(self): """ Decide if ``self`` is a suitable origin. A function is a suitable origin iff: * none of the ai equals bj + n, with n a non-negative integer * none of the ai is zero * none of the bj is a non-positive integer Note that this gives meaningful results only when none of the indices are symbolic. """ for a in self.ap: for b in self.bq: if (a - b).is_integer and (a - b).is_negative is False: return False for a in self.ap: if a == 0: return False for b in self.bq: if b.is_integer and b.is_nonpositive: return False return True class G_Function(Expr): """ A Meijer G-function. """ def __new__(cls, an, ap, bm, bq): obj = super(G_Function, cls).__new__(cls) obj.an = Tuple(*list(map(expand, an))) obj.ap = Tuple(*list(map(expand, ap))) obj.bm = Tuple(*list(map(expand, bm))) obj.bq = Tuple(*list(map(expand, bq))) return obj @property def args(self): return (self.an, self.ap, self.bm, self.bq) def _hashable_content(self): return super(G_Function, self)._hashable_content() + self.args def __call__(self, z): return meijerg(self.an, self.ap, self.bm, self.bq, z) def compute_buckets(self): """ Compute buckets for the fours sets of parameters. We guarantee that any two equal Mod objects returned are actually the same, and that the buckets are sorted by real part (an and bq descendending, bm and ap ascending). Examples ======== >>> from sympy.simplify.hyperexpand import G_Function >>> from sympy.abc import y >>> from sympy import S, symbols >>> a, b = [1, 3, 2, S(3)/2], [1 + y, y, 2, y + 3] >>> G_Function(a, b, [2], [y]).compute_buckets() ({0: [3, 2, 1], 1/2: [3/2]}, {0: [2], y: [y, y + 1, y + 3]}, {0: [2]}, {y: [y]}) """ dicts = pan, pap, pbm, pbq = [defaultdict(list) for i in range(4)] for dic, lis in zip(dicts, (self.an, self.ap, self.bm, self.bq)): for x in lis: dic[_mod1(x)].append(x) for dic, flip in zip(dicts, (True, False, False, True)): for m, items in dic.items(): x0 = items[0] items.sort(key=lambda x: x - x0, reverse=flip) dic[m] = items return tuple([dict(w) for w in dicts]) @property def signature(self): return (len(self.an), len(self.ap), len(self.bm), len(self.bq)) # Dummy variable. _x = Dummy('x') class Formula(object): """ This class represents hypergeometric formulae. Its data members are: - z, the argument - closed_form, the closed form expression - symbols, the free symbols (parameters) in the formula - func, the function - B, C, M (see _compute_basis) Examples ======== >>> from sympy.abc import a, b, z >>> from sympy.simplify.hyperexpand import Formula, Hyper_Function >>> func = Hyper_Function((a/2, a/3 + b, (1+a)/2), (a, b, (a+b)/7)) >>> f = Formula(func, z, None, [a, b]) """ def _compute_basis(self, closed_form): """ Compute a set of functions B=(f1, ..., fn), a nxn matrix M and a 1xn matrix C such that: closed_form = C B z d/dz B = M B. """ from sympy.matrices import Matrix, eye, zeros afactors = [_x + a for a in self.func.ap] bfactors = [_x + b - 1 for b in self.func.bq] expr = _x*Mul(*bfactors) - self.z*Mul(*afactors) poly = Poly(expr, _x) n = poly.degree() - 1 b = [closed_form] for _ in range(n): b.append(self.z*b[-1].diff(self.z)) self.B = Matrix(b) self.C = Matrix([[1] + [0]*n]) m = eye(n) m = m.col_insert(0, zeros(n, 1)) l = poly.all_coeffs()[1:] l.reverse() self.M = m.row_insert(n, -Matrix([l])/poly.all_coeffs()[0]) def __init__(self, func, z, res, symbols, B=None, C=None, M=None): z = sympify(z) res = sympify(res) symbols = [x for x in sympify(symbols) if func.has(x)] self.z = z self.symbols = symbols self.B = B self.C = C self.M = M self.func = func # TODO with symbolic parameters, it could be advantageous # (for prettier answers) to compute a basis only *after* # instantiation if res is not None: self._compute_basis(res) @property def closed_form(self): return (self.C*self.B)[0] def find_instantiations(self, func): """ Find substitutions of the free symbols that match ``func``. Return the substitution dictionaries as a list. Note that the returned instantiations need not actually match, or be valid! """ from sympy.solvers import solve ap = func.ap bq = func.bq if len(ap) != len(self.func.ap) or len(bq) != len(self.func.bq): raise TypeError('Cannot instantiate other number of parameters') symbol_values = [] for a in self.symbols: if a in self.func.ap.args: symbol_values.append(ap) elif a in self.func.bq.args: symbol_values.append(bq) else: raise ValueError("At least one of the parameters of the " "formula must be equal to %s" % (a,)) base_repl = [dict(list(zip(self.symbols, values))) for values in product(*symbol_values)] abuckets, bbuckets = [sift(params, _mod1) for params in [ap, bq]] a_inv, b_inv = [dict((a, len(vals)) for a, vals in bucket.items()) for bucket in [abuckets, bbuckets]] critical_values = [[0] for _ in self.symbols] result = [] _n = Dummy() for repl in base_repl: symb_a, symb_b = [sift(params, lambda x: _mod1(x.xreplace(repl))) for params in [self.func.ap, self.func.bq]] for bucket, obucket in [(abuckets, symb_a), (bbuckets, symb_b)]: for mod in set(list(bucket.keys()) + list(obucket.keys())): if (not mod in bucket) or (not mod in obucket) \ or len(bucket[mod]) != len(obucket[mod]): break for a, vals in zip(self.symbols, critical_values): if repl[a].free_symbols: continue exprs = [expr for expr in obucket[mod] if expr.has(a)] repl0 = repl.copy() repl0[a] += _n for expr in exprs: for target in bucket[mod]: n0, = solve(expr.xreplace(repl0) - target, _n) if n0.free_symbols: raise ValueError("Value should not be true") vals.append(n0) else: values = [] for a, vals in zip(self.symbols, critical_values): a0 = repl[a] min_ = floor(min(vals)) max_ = ceiling(max(vals)) values.append([a0 + n for n in range(min_, max_ + 1)]) result.extend(dict(list(zip(self.symbols, l))) for l in product(*values)) return result class FormulaCollection(object): """ A collection of formulae to use as origins. """ def __init__(self): """ Doing this globally at module init time is a pain ... """ self.symbolic_formulae = {} self.concrete_formulae = {} self.formulae = [] add_formulae(self.formulae) # Now process the formulae into a helpful form. # These dicts are indexed by (p, q). for f in self.formulae: sizes = f.func.sizes if len(f.symbols) > 0: self.symbolic_formulae.setdefault(sizes, []).append(f) else: inv = f.func.build_invariants() self.concrete_formulae.setdefault(sizes, {})[inv] = f def lookup_origin(self, func): """ Given the suitable target ``func``, try to find an origin in our knowledge base. Examples ======== >>> from sympy.simplify.hyperexpand import (FormulaCollection, ... Hyper_Function) >>> f = FormulaCollection() >>> f.lookup_origin(Hyper_Function((), ())).closed_form exp(_z) >>> f.lookup_origin(Hyper_Function([1], ())).closed_form HyperRep_power1(-1, _z) >>> from sympy import S >>> i = Hyper_Function([S('1/4'), S('3/4 + 4')], [S.Half]) >>> f.lookup_origin(i).closed_form HyperRep_sqrts1(-1/4, _z) """ inv = func.build_invariants() sizes = func.sizes if sizes in self.concrete_formulae and \ inv in self.concrete_formulae[sizes]: return self.concrete_formulae[sizes][inv] # We don't have a concrete formula. Try to instantiate. if not sizes in self.symbolic_formulae: return None # Too bad... possible = [] for f in self.symbolic_formulae[sizes]: repls = f.find_instantiations(func) for repl in repls: func2 = f.func.xreplace(repl) if not func2._is_suitable_origin(): continue diff = func2.difficulty(func) if diff == -1: continue possible.append((diff, repl, f, func2)) # find the nearest origin possible.sort(key=lambda x: x[0]) for _, repl, f, func2 in possible: f2 = Formula(func2, f.z, None, [], f.B.subs(repl), f.C.subs(repl), f.M.subs(repl)) if not any(e.has(S.NaN, oo, -oo, zoo) for e in [f2.B, f2.M, f2.C]): return f2 else: return None class MeijerFormula(object): """ This class represents a Meijer G-function formula. Its data members are: - z, the argument - symbols, the free symbols (parameters) in the formula - func, the function - B, C, M (c/f ordinary Formula) """ def __init__(self, an, ap, bm, bq, z, symbols, B, C, M, matcher): an, ap, bm, bq = [Tuple(*list(map(expand, w))) for w in [an, ap, bm, bq]] self.func = G_Function(an, ap, bm, bq) self.z = z self.symbols = symbols self._matcher = matcher self.B = B self.C = C self.M = M @property def closed_form(self): return (self.C*self.B)[0] def try_instantiate(self, func): """ Try to instantiate the current formula to (almost) match func. This uses the _matcher passed on init. """ if func.signature != self.func.signature: return None res = self._matcher(func) if res is not None: subs, newfunc = res return MeijerFormula(newfunc.an, newfunc.ap, newfunc.bm, newfunc.bq, self.z, [], self.B.subs(subs), self.C.subs(subs), self.M.subs(subs), None) class MeijerFormulaCollection(object): """ This class holds a collection of meijer g formulae. """ def __init__(self): formulae = [] add_meijerg_formulae(formulae) self.formulae = defaultdict(list) for formula in formulae: self.formulae[formula.func.signature].append(formula) self.formulae = dict(self.formulae) def lookup_origin(self, func): """ Try to find a formula that matches func. """ if not func.signature in self.formulae: return None for formula in self.formulae[func.signature]: res = formula.try_instantiate(func) if res is not None: return res class Operator(object): """ Base class for operators to be applied to our functions. These operators are differential operators. They are by convention expressed in the variable D = z*d/dz (although this base class does not actually care). Note that when the operator is applied to an object, we typically do *not* blindly differentiate but instead use a different representation of the z*d/dz operator (see make_derivative_operator). To subclass from this, define a __init__ method that initializes a self._poly variable. This variable stores a polynomial. By convention the generator is z*d/dz, and acts to the right of all coefficients. Thus this poly x**2 + 2*z*x + 1 represents the differential operator (z*d/dz)**2 + 2*z**2*d/dz. This class is used only in the implementation of the hypergeometric function expansion algorithm. """ def apply(self, obj, op): """ Apply ``self`` to the object ``obj``, where the generator is ``op``. Examples ======== >>> from sympy.simplify.hyperexpand import Operator >>> from sympy.polys.polytools import Poly >>> from sympy.abc import x, y, z >>> op = Operator() >>> op._poly = Poly(x**2 + z*x + y, x) >>> op.apply(z**7, lambda f: f.diff(z)) y*z**7 + 7*z**7 + 42*z**5 """ coeffs = self._poly.all_coeffs() coeffs.reverse() diffs = [obj] for c in coeffs[1:]: diffs.append(op(diffs[-1])) r = coeffs[0]*diffs[0] for c, d in zip(coeffs[1:], diffs[1:]): r += c*d return r class MultOperator(Operator): """ Simply multiply by a "constant" """ def __init__(self, p): self._poly = Poly(p, _x) class ShiftA(Operator): """ Increment an upper index. """ def __init__(self, ai): ai = sympify(ai) if ai == 0: raise ValueError('Cannot increment zero upper index.') self._poly = Poly(_x/ai + 1, _x) def __str__(self): return '<Increment upper %s.>' % (1/self._poly.all_coeffs()[0]) class ShiftB(Operator): """ Decrement a lower index. """ def __init__(self, bi): bi = sympify(bi) if bi == 1: raise ValueError('Cannot decrement unit lower index.') self._poly = Poly(_x/(bi - 1) + 1, _x) def __str__(self): return '<Decrement lower %s.>' % (1/self._poly.all_coeffs()[0] + 1) class UnShiftA(Operator): """ Decrement an upper index. """ def __init__(self, ap, bq, i, z): """ Note: i counts from zero! """ ap, bq, i = list(map(sympify, [ap, bq, i])) self._ap = ap self._bq = bq self._i = i ap = list(ap) bq = list(bq) ai = ap.pop(i) - 1 if ai == 0: raise ValueError('Cannot decrement unit upper index.') m = Poly(z*ai, _x) for a in ap: m *= Poly(_x + a, _x) A = Dummy('A') n = D = Poly(ai*A - ai, A) for b in bq: n *= (D + b - 1) b0 = -n.nth(0) if b0 == 0: raise ValueError('Cannot decrement upper index: ' 'cancels with lower') n = Poly(Poly(n.all_coeffs()[:-1], A).as_expr().subs(A, _x/ai + 1), _x) self._poly = Poly((n - m)/b0, _x) def __str__(self): return '<Decrement upper index #%s of %s, %s.>' % (self._i, self._ap, self._bq) class UnShiftB(Operator): """ Increment a lower index. """ def __init__(self, ap, bq, i, z): """ Note: i counts from zero! """ ap, bq, i = list(map(sympify, [ap, bq, i])) self._ap = ap self._bq = bq self._i = i ap = list(ap) bq = list(bq) bi = bq.pop(i) + 1 if bi == 0: raise ValueError('Cannot increment -1 lower index.') m = Poly(_x*(bi - 1), _x) for b in bq: m *= Poly(_x + b - 1, _x) B = Dummy('B') D = Poly((bi - 1)*B - bi + 1, B) n = Poly(z, B) for a in ap: n *= (D + a) b0 = n.nth(0) if b0 == 0: raise ValueError('Cannot increment index: cancels with upper') n = Poly(Poly(n.all_coeffs()[:-1], B).as_expr().subs( B, _x/(bi - 1) + 1), _x) self._poly = Poly((m - n)/b0, _x) def __str__(self): return '<Increment lower index #%s of %s, %s.>' % (self._i, self._ap, self._bq) class MeijerShiftA(Operator): """ Increment an upper b index. """ def __init__(self, bi): bi = sympify(bi) self._poly = Poly(bi - _x, _x) def __str__(self): return '<Increment upper b=%s.>' % (self._poly.all_coeffs()[1]) class MeijerShiftB(Operator): """ Decrement an upper a index. """ def __init__(self, bi): bi = sympify(bi) self._poly = Poly(1 - bi + _x, _x) def __str__(self): return '<Decrement upper a=%s.>' % (1 - self._poly.all_coeffs()[1]) class MeijerShiftC(Operator): """ Increment a lower b index. """ def __init__(self, bi): bi = sympify(bi) self._poly = Poly(-bi + _x, _x) def __str__(self): return '<Increment lower b=%s.>' % (-self._poly.all_coeffs()[1]) class MeijerShiftD(Operator): """ Decrement a lower a index. """ def __init__(self, bi): bi = sympify(bi) self._poly = Poly(bi - 1 - _x, _x) def __str__(self): return '<Decrement lower a=%s.>' % (self._poly.all_coeffs()[1] + 1) class MeijerUnShiftA(Operator): """ Decrement an upper b index. """ def __init__(self, an, ap, bm, bq, i, z): """ Note: i counts from zero! """ an, ap, bm, bq, i = list(map(sympify, [an, ap, bm, bq, i])) self._an = an self._ap = ap self._bm = bm self._bq = bq self._i = i an = list(an) ap = list(ap) bm = list(bm) bq = list(bq) bi = bm.pop(i) - 1 m = Poly(1, _x) for b in bm: m *= Poly(b - _x, _x) for b in bq: m *= Poly(_x - b, _x) A = Dummy('A') D = Poly(bi - A, A) n = Poly(z, A) for a in an: n *= (D + 1 - a) for a in ap: n *= (-D + a - 1) b0 = n.nth(0) if b0 == 0: raise ValueError('Cannot decrement upper b index (cancels)') n = Poly(Poly(n.all_coeffs()[:-1], A).as_expr().subs(A, bi - _x), _x) self._poly = Poly((m - n)/b0, _x) def __str__(self): return '<Decrement upper b index #%s of %s, %s, %s, %s.>' % (self._i, self._an, self._ap, self._bm, self._bq) class MeijerUnShiftB(Operator): """ Increment an upper a index. """ def __init__(self, an, ap, bm, bq, i, z): """ Note: i counts from zero! """ an, ap, bm, bq, i = list(map(sympify, [an, ap, bm, bq, i])) self._an = an self._ap = ap self._bm = bm self._bq = bq self._i = i an = list(an) ap = list(ap) bm = list(bm) bq = list(bq) ai = an.pop(i) + 1 m = Poly(z, _x) for a in an: m *= Poly(1 - a + _x, _x) for a in ap: m *= Poly(a - 1 - _x, _x) B = Dummy('B') D = Poly(B + ai - 1, B) n = Poly(1, B) for b in bm: n *= (-D + b) for b in bq: n *= (D - b) b0 = n.nth(0) if b0 == 0: raise ValueError('Cannot increment upper a index (cancels)') n = Poly(Poly(n.all_coeffs()[:-1], B).as_expr().subs( B, 1 - ai + _x), _x) self._poly = Poly((m - n)/b0, _x) def __str__(self): return '<Increment upper a index #%s of %s, %s, %s, %s.>' % (self._i, self._an, self._ap, self._bm, self._bq) class MeijerUnShiftC(Operator): """ Decrement a lower b index. """ # XXX this is "essentially" the same as MeijerUnShiftA. This "essentially" # can be made rigorous using the functional equation G(1/z) = G'(z), # where G' denotes a G function of slightly altered parameters. # However, sorting out the details seems harder than just coding it # again. def __init__(self, an, ap, bm, bq, i, z): """ Note: i counts from zero! """ an, ap, bm, bq, i = list(map(sympify, [an, ap, bm, bq, i])) self._an = an self._ap = ap self._bm = bm self._bq = bq self._i = i an = list(an) ap = list(ap) bm = list(bm) bq = list(bq) bi = bq.pop(i) - 1 m = Poly(1, _x) for b in bm: m *= Poly(b - _x, _x) for b in bq: m *= Poly(_x - b, _x) C = Dummy('C') D = Poly(bi + C, C) n = Poly(z, C) for a in an: n *= (D + 1 - a) for a in ap: n *= (-D + a - 1) b0 = n.nth(0) if b0 == 0: raise ValueError('Cannot decrement lower b index (cancels)') n = Poly(Poly(n.all_coeffs()[:-1], C).as_expr().subs(C, _x - bi), _x) self._poly = Poly((m - n)/b0, _x) def __str__(self): return '<Decrement lower b index #%s of %s, %s, %s, %s.>' % (self._i, self._an, self._ap, self._bm, self._bq) class MeijerUnShiftD(Operator): """ Increment a lower a index. """ # XXX This is essentially the same as MeijerUnShiftA. # See comment at MeijerUnShiftC. def __init__(self, an, ap, bm, bq, i, z): """ Note: i counts from zero! """ an, ap, bm, bq, i = list(map(sympify, [an, ap, bm, bq, i])) self._an = an self._ap = ap self._bm = bm self._bq = bq self._i = i an = list(an) ap = list(ap) bm = list(bm) bq = list(bq) ai = ap.pop(i) + 1 m = Poly(z, _x) for a in an: m *= Poly(1 - a + _x, _x) for a in ap: m *= Poly(a - 1 - _x, _x) B = Dummy('B') # - this is the shift operator `D_I` D = Poly(ai - 1 - B, B) n = Poly(1, B) for b in bm: n *= (-D + b) for b in bq: n *= (D - b) b0 = n.nth(0) if b0 == 0: raise ValueError('Cannot increment lower a index (cancels)') n = Poly(Poly(n.all_coeffs()[:-1], B).as_expr().subs( B, ai - 1 - _x), _x) self._poly = Poly((m - n)/b0, _x) def __str__(self): return '<Increment lower a index #%s of %s, %s, %s, %s.>' % (self._i, self._an, self._ap, self._bm, self._bq) class ReduceOrder(Operator): """ Reduce Order by cancelling an upper and a lower index. """ def __new__(cls, ai, bj): """ For convenience if reduction is not possible, return None. """ ai = sympify(ai) bj = sympify(bj) n = ai - bj if not n.is_Integer or n < 0: return None if bj.is_integer and bj.is_nonpositive: return None expr = Operator.__new__(cls) p = S(1) for k in range(n): p *= (_x + bj + k)/(bj + k) expr._poly = Poly(p, _x) expr._a = ai expr._b = bj return expr @classmethod def _meijer(cls, b, a, sign): """ Cancel b + sign*s and a + sign*s This is for meijer G functions. """ b = sympify(b) a = sympify(a) n = b - a if n.is_negative or not n.is_Integer: return None expr = Operator.__new__(cls) p = S(1) for k in range(n): p *= (sign*_x + a + k) expr._poly = Poly(p, _x) if sign == -1: expr._a = b expr._b = a else: expr._b = Add(1, a - 1, evaluate=False) expr._a = Add(1, b - 1, evaluate=False) return expr @classmethod def meijer_minus(cls, b, a): return cls._meijer(b, a, -1) @classmethod def meijer_plus(cls, a, b): return cls._meijer(1 - a, 1 - b, 1) def __str__(self): return '<Reduce order by cancelling upper %s with lower %s.>' % \ (self._a, self._b) def _reduce_order(ap, bq, gen, key): """ Order reduction algorithm used in Hypergeometric and Meijer G """ ap = list(ap) bq = list(bq) ap.sort(key=key) bq.sort(key=key) nap = [] # we will edit bq in place operators = [] for a in ap: op = None for i in range(len(bq)): op = gen(a, bq[i]) if op is not None: bq.pop(i) break if op is None: nap.append(a) else: operators.append(op) return nap, bq, operators def reduce_order(func): """ Given the hypergeometric function ``func``, find a sequence of operators to reduces order as much as possible. Return (newfunc, [operators]), where applying the operators to the hypergeometric function newfunc yields func. Examples ======== >>> from sympy.simplify.hyperexpand import reduce_order, Hyper_Function >>> reduce_order(Hyper_Function((1, 2), (3, 4))) (Hyper_Function((1, 2), (3, 4)), []) >>> reduce_order(Hyper_Function((1,), (1,))) (Hyper_Function((), ()), [<Reduce order by cancelling upper 1 with lower 1.>]) >>> reduce_order(Hyper_Function((2, 4), (3, 3))) (Hyper_Function((2,), (3,)), [<Reduce order by cancelling upper 4 with lower 3.>]) """ nap, nbq, operators = _reduce_order(func.ap, func.bq, ReduceOrder, default_sort_key) return Hyper_Function(Tuple(*nap), Tuple(*nbq)), operators def reduce_order_meijer(func): """ Given the Meijer G function parameters, ``func``, find a sequence of operators that reduces order as much as possible. Return newfunc, [operators]. Examples ======== >>> from sympy.simplify.hyperexpand import (reduce_order_meijer, ... G_Function) >>> reduce_order_meijer(G_Function([3, 4], [5, 6], [3, 4], [1, 2]))[0] G_Function((4, 3), (5, 6), (3, 4), (2, 1)) >>> reduce_order_meijer(G_Function([3, 4], [5, 6], [3, 4], [1, 8]))[0] G_Function((3,), (5, 6), (3, 4), (1,)) >>> reduce_order_meijer(G_Function([3, 4], [5, 6], [7, 5], [1, 5]))[0] G_Function((3,), (), (), (1,)) >>> reduce_order_meijer(G_Function([3, 4], [5, 6], [7, 5], [5, 3]))[0] G_Function((), (), (), ()) """ nan, nbq, ops1 = _reduce_order(func.an, func.bq, ReduceOrder.meijer_plus, lambda x: default_sort_key(-x)) nbm, nap, ops2 = _reduce_order(func.bm, func.ap, ReduceOrder.meijer_minus, default_sort_key) return G_Function(nan, nap, nbm, nbq), ops1 + ops2 def make_derivative_operator(M, z): """ Create a derivative operator, to be passed to Operator.apply. """ def doit(C): r = z*C.diff(z) + C*M r = r.applyfunc(make_simp(z)) return r return doit def apply_operators(obj, ops, op): """ Apply the list of operators ``ops`` to object ``obj``, substituting ``op`` for the generator. """ res = obj for o in reversed(ops): res = o.apply(res, op) return res def devise_plan(target, origin, z): """ Devise a plan (consisting of shift and un-shift operators) to be applied to the hypergeometric function ``target`` to yield ``origin``. Returns a list of operators. Examples ======== >>> from sympy.simplify.hyperexpand import devise_plan, Hyper_Function >>> from sympy.abc import z Nothing to do: >>> devise_plan(Hyper_Function((1, 2), ()), Hyper_Function((1, 2), ()), z) [] >>> devise_plan(Hyper_Function((), (1, 2)), Hyper_Function((), (1, 2)), z) [] Very simple plans: >>> devise_plan(Hyper_Function((2,), ()), Hyper_Function((1,), ()), z) [<Increment upper 1.>] >>> devise_plan(Hyper_Function((), (2,)), Hyper_Function((), (1,)), z) [<Increment lower index #0 of [], [1].>] Several buckets: >>> from sympy import S >>> devise_plan(Hyper_Function((1, S.Half), ()), ... Hyper_Function((2, S('3/2')), ()), z) #doctest: +NORMALIZE_WHITESPACE [<Decrement upper index #0 of [3/2, 1], [].>, <Decrement upper index #0 of [2, 3/2], [].>] A slightly more complicated plan: >>> devise_plan(Hyper_Function((1, 3), ()), Hyper_Function((2, 2), ()), z) [<Increment upper 2.>, <Decrement upper index #0 of [2, 2], [].>] Another more complicated plan: (note that the ap have to be shifted first!) >>> devise_plan(Hyper_Function((1, -1), (2,)), Hyper_Function((3, -2), (4,)), z) [<Decrement lower 3.>, <Decrement lower 4.>, <Decrement upper index #1 of [-1, 2], [4].>, <Decrement upper index #1 of [-1, 3], [4].>, <Increment upper -2.>] """ abuckets, bbuckets, nabuckets, nbbuckets = [sift(params, _mod1) for params in (target.ap, target.bq, origin.ap, origin.bq)] if len(list(abuckets.keys())) != len(list(nabuckets.keys())) or \ len(list(bbuckets.keys())) != len(list(nbbuckets.keys())): raise ValueError('%s not reachable from %s' % (target, origin)) ops = [] def do_shifts(fro, to, inc, dec): ops = [] for i in range(len(fro)): if to[i] - fro[i] > 0: sh = inc ch = 1 else: sh = dec ch = -1 while to[i] != fro[i]: ops += [sh(fro, i)] fro[i] += ch return ops def do_shifts_a(nal, nbk, al, aother, bother): """ Shift us from (nal, nbk) to (al, nbk). """ return do_shifts(nal, al, lambda p, i: ShiftA(p[i]), lambda p, i: UnShiftA(p + aother, nbk + bother, i, z)) def do_shifts_b(nal, nbk, bk, aother, bother): """ Shift us from (nal, nbk) to (nal, bk). """ return do_shifts(nbk, bk, lambda p, i: UnShiftB(nal + aother, p + bother, i, z), lambda p, i: ShiftB(p[i])) for r in sorted(list(abuckets.keys()) + list(bbuckets.keys()), key=default_sort_key): al = () nal = () bk = () nbk = () if r in abuckets: al = abuckets[r] nal = nabuckets[r] if r in bbuckets: bk = bbuckets[r] nbk = nbbuckets[r] if len(al) != len(nal) or len(bk) != len(nbk): raise ValueError('%s not reachable from %s' % (target, origin)) al, nal, bk, nbk = [sorted(list(w), key=default_sort_key) for w in [al, nal, bk, nbk]] def others(dic, key): l = [] for k, value in dic.items(): if k != key: l += list(dic[k]) return l aother = others(nabuckets, r) bother = others(nbbuckets, r) if len(al) == 0: # there can be no complications, just shift the bs as we please ops += do_shifts_b([], nbk, bk, aother, bother) elif len(bk) == 0: # there can be no complications, just shift the as as we please ops += do_shifts_a(nal, [], al, aother, bother) else: namax = nal[-1] amax = al[-1] if nbk[0] - namax <= 0 or bk[0] - amax <= 0: raise ValueError('Non-suitable parameters.') if namax - amax > 0: # we are going to shift down - first do the as, then the bs ops += do_shifts_a(nal, nbk, al, aother, bother) ops += do_shifts_b(al, nbk, bk, aother, bother) else: # we are going to shift up - first do the bs, then the as ops += do_shifts_b(nal, nbk, bk, aother, bother) ops += do_shifts_a(nal, bk, al, aother, bother) nabuckets[r] = al nbbuckets[r] = bk ops.reverse() return ops def try_shifted_sum(func, z): """ Try to recognise a hypergeometric sum that starts from k > 0. """ abuckets, bbuckets = sift(func.ap, _mod1), sift(func.bq, _mod1) if len(abuckets[S(0)]) != 1: return None r = abuckets[S(0)][0] if r <= 0: return None if not S(0) in bbuckets: return None l = list(bbuckets[S(0)]) l.sort() k = l[0] if k <= 0: return None nap = list(func.ap) nap.remove(r) nbq = list(func.bq) nbq.remove(k) k -= 1 nap = [x - k for x in nap] nbq = [x - k for x in nbq] ops = [] for n in range(r - 1): ops.append(ShiftA(n + 1)) ops.reverse() fac = factorial(k)/z**k for a in nap: fac /= rf(a, k) for b in nbq: fac *= rf(b, k) ops += [MultOperator(fac)] p = 0 for n in range(k): m = z**n/factorial(n) for a in nap: m *= rf(a, n) for b in nbq: m /= rf(b, n) p += m return Hyper_Function(nap, nbq), ops, -p def try_polynomial(func, z): """ Recognise polynomial cases. Returns None if not such a case. Requires order to be fully reduced. """ abuckets, bbuckets = sift(func.ap, _mod1), sift(func.bq, _mod1) a0 = abuckets[S(0)] b0 = bbuckets[S(0)] a0.sort() b0.sort() al0 = [x for x in a0 if x <= 0] bl0 = [x for x in b0 if x <= 0] if bl0 and all(a < bl0[-1] for a in al0): return oo if not al0: return None a = al0[-1] fac = 1 res = S(1) for n in Tuple(*list(range(-a))): fac *= z fac /= n + 1 for a in func.ap: fac *= a + n for b in func.bq: fac /= b + n res += fac return res def try_lerchphi(func): """ Try to find an expression for Hyper_Function ``func`` in terms of Lerch Transcendents. Return None if no such expression can be found. """ # This is actually quite simple, and is described in Roach's paper, # section 18. # We don't need to implement the reduction to polylog here, this # is handled by expand_func. from sympy.matrices import Matrix, zeros from sympy.polys import apart # First we need to figure out if the summation coefficient is a rational # function of the summation index, and construct that rational function. abuckets, bbuckets = sift(func.ap, _mod1), sift(func.bq, _mod1) paired = {} for key, value in abuckets.items(): if key != 0 and not key in bbuckets: return None bvalue = bbuckets[key] paired[key] = (list(value), list(bvalue)) bbuckets.pop(key, None) if bbuckets != {}: return None if not S(0) in abuckets: return None aints, bints = paired[S(0)] # Account for the additional n! in denominator paired[S(0)] = (aints, bints + [1]) t = Dummy('t') numer = S(1) denom = S(1) for key, (avalue, bvalue) in paired.items(): if len(avalue) != len(bvalue): return None # Note that since order has been reduced fully, all the b are # bigger than all the a they differ from by an integer. In particular # if there are any negative b left, this function is not well-defined. for a, b in zip(avalue, bvalue): if (a - b).is_positive: k = a - b numer *= rf(b + t, k) denom *= rf(b, k) else: k = b - a numer *= rf(a, k) denom *= rf(a + t, k) # Now do a partial fraction decomposition. # We assemble two structures: a list monomials of pairs (a, b) representing # a*t**b (b a non-negative integer), and a dict terms, where # terms[a] = [(b, c)] means that there is a term b/(t-a)**c. part = apart(numer/denom, t) args = Add.make_args(part) monomials = [] terms = {} for arg in args: numer, denom = arg.as_numer_denom() if not denom.has(t): p = Poly(numer, t) if not p.is_monomial: raise TypeError("p should be monomial") ((b, ), a) = p.LT() monomials += [(a/denom, b)] continue if numer.has(t): raise NotImplementedError('Need partial fraction decomposition' ' with linear denominators') indep, [dep] = denom.as_coeff_mul(t) n = 1 if dep.is_Pow: n = dep.exp dep = dep.base if dep == t: a == 0 elif dep.is_Add: a, tmp = dep.as_independent(t) b = 1 if tmp != t: b, _ = tmp.as_independent(t) if dep != b*t + a: raise NotImplementedError('unrecognised form %s' % dep) a /= b indep *= b**n else: raise NotImplementedError('unrecognised form of partial fraction') terms.setdefault(a, []).append((numer/indep, n)) # Now that we have this information, assemble our formula. All the # monomials yield rational functions and go into one basis element. # The terms[a] are related by differentiation. If the largest exponent is # n, we need lerchphi(z, k, a) for k = 1, 2, ..., n. # deriv maps a basis to its derivative, expressed as a C(z)-linear # combination of other basis elements. deriv = {} coeffs = {} z = Dummy('z') monomials.sort(key=lambda x: x[1]) mon = {0: 1/(1 - z)} if monomials: for k in range(monomials[-1][1]): mon[k + 1] = z*mon[k].diff(z) for a, n in monomials: coeffs.setdefault(S(1), []).append(a*mon[n]) for a, l in terms.items(): for c, k in l: coeffs.setdefault(lerchphi(z, k, a), []).append(c) l.sort(key=lambda x: x[1]) for k in range(2, l[-1][1] + 1): deriv[lerchphi(z, k, a)] = [(-a, lerchphi(z, k, a)), (1, lerchphi(z, k - 1, a))] deriv[lerchphi(z, 1, a)] = [(-a, lerchphi(z, 1, a)), (1/(1 - z), S(1))] trans = {} for n, b in enumerate([S(1)] + list(deriv.keys())): trans[b] = n basis = [expand_func(b) for (b, _) in sorted(list(trans.items()), key=lambda x:x[1])] B = Matrix(basis) C = Matrix([[0]*len(B)]) for b, c in coeffs.items(): C[trans[b]] = Add(*c) M = zeros(len(B)) for b, l in deriv.items(): for c, b2 in l: M[trans[b], trans[b2]] = c return Formula(func, z, None, [], B, C, M) def build_hypergeometric_formula(func): """ Create a formula object representing the hypergeometric function ``func``. """ # We know that no `ap` are negative integers, otherwise "detect poly" # would have kicked in. However, `ap` could be empty. In this case we can # use a different basis. # I'm not aware of a basis that works in all cases. from sympy import zeros, Matrix, eye z = Dummy('z') if func.ap: afactors = [_x + a for a in func.ap] bfactors = [_x + b - 1 for b in func.bq] expr = _x*Mul(*bfactors) - z*Mul(*afactors) poly = Poly(expr, _x) n = poly.degree() basis = [] M = zeros(n) for k in range(n): a = func.ap[0] + k basis += [hyper([a] + list(func.ap[1:]), func.bq, z)] if k < n - 1: M[k, k] = -a M[k, k + 1] = a B = Matrix(basis) C = Matrix([[1] + [0]*(n - 1)]) derivs = [eye(n)] for k in range(n): derivs.append(M*derivs[k]) l = poly.all_coeffs() l.reverse() res = [0]*n for k, c in enumerate(l): for r, d in enumerate(C*derivs[k]): res[r] += c*d for k, c in enumerate(res): M[n - 1, k] = -c/derivs[n - 1][0, n - 1]/poly.all_coeffs()[0] return Formula(func, z, None, [], B, C, M) else: # Since there are no `ap`, none of the `bq` can be non-positive # integers. basis = [] bq = list(func.bq[:]) for i in range(len(bq)): basis += [hyper([], bq, z)] bq[i] += 1 basis += [hyper([], bq, z)] B = Matrix(basis) n = len(B) C = Matrix([[1] + [0]*(n - 1)]) M = zeros(n) M[0, n - 1] = z/Mul(*func.bq) for k in range(1, n): M[k, k - 1] = func.bq[k - 1] M[k, k] = -func.bq[k - 1] return Formula(func, z, None, [], B, C, M) def hyperexpand_special(ap, bq, z): """ Try to find a closed-form expression for hyper(ap, bq, z), where ``z`` is supposed to be a "special" value, e.g. 1. This function tries various of the classical summation formulae (Gauss, Saalschuetz, etc). """ # This code is very ad-hoc. There are many clever algorithms # (notably Zeilberger's) related to this problem. # For now we just want a few simple cases to work. p, q = len(ap), len(bq) z_ = z z = unpolarify(z) if z == 0: return S.One if p == 2 and q == 1: # 2F1 a, b, c = ap + bq if z == 1: # Gauss return gamma(c - a - b)*gamma(c)/gamma(c - a)/gamma(c - b) if z == -1 and simplify(b - a + c) == 1: b, a = a, b if z == -1 and simplify(a - b + c) == 1: # Kummer if b.is_integer and b.is_negative: return 2*cos(pi*b/2)*gamma(-b)*gamma(b - a + 1) \ /gamma(-b/2)/gamma(b/2 - a + 1) else: return gamma(b/2 + 1)*gamma(b - a + 1) \ /gamma(b + 1)/gamma(b/2 - a + 1) # TODO tons of more formulae # investigate what algorithms exist return hyper(ap, bq, z_) _collection = None def _hyperexpand(func, z, ops0=[], z0=Dummy('z0'), premult=1, prem=0, rewrite='default'): """ Try to find an expression for the hypergeometric function ``func``. The result is expressed in terms of a dummy variable z0. Then it is multiplied by premult. Then ops0 is applied. premult must be a*z**prem for some a independent of z. """ if z is S.Zero: return S.One z = polarify(z, subs=False) if rewrite == 'default': rewrite = 'nonrepsmall' def carryout_plan(f, ops): C = apply_operators(f.C.subs(f.z, z0), ops, make_derivative_operator(f.M.subs(f.z, z0), z0)) from sympy import eye C = apply_operators(C, ops0, make_derivative_operator(f.M.subs(f.z, z0) + prem*eye(f.M.shape[0]), z0)) if premult == 1: C = C.applyfunc(make_simp(z0)) r = C*f.B.subs(f.z, z0)*premult res = r[0].subs(z0, z) if rewrite: res = res.rewrite(rewrite) return res # TODO # The following would be possible: # *) PFD Duplication (see Kelly Roach's paper) # *) In a similar spirit, try_lerchphi() can be generalised considerably. global _collection if _collection is None: _collection = FormulaCollection() debug('Trying to expand hypergeometric function ', func) # First reduce order as much as possible. func, ops = reduce_order(func) if ops: debug(' Reduced order to ', func) else: debug(' Could not reduce order.') # Now try polynomial cases res = try_polynomial(func, z0) if res is not None: debug(' Recognised polynomial.') p = apply_operators(res, ops, lambda f: z0*f.diff(z0)) p = apply_operators(p*premult, ops0, lambda f: z0*f.diff(z0)) return unpolarify(simplify(p).subs(z0, z)) # Try to recognise a shifted sum. p = S(0) res = try_shifted_sum(func, z0) if res is not None: func, nops, p = res debug(' Recognised shifted sum, reduced order to ', func) ops += nops # apply the plan for poly p = apply_operators(p, ops, lambda f: z0*f.diff(z0)) p = apply_operators(p*premult, ops0, lambda f: z0*f.diff(z0)) p = simplify(p).subs(z0, z) # Try special expansions early. if unpolarify(z) in [1, -1] and (len(func.ap), len(func.bq)) == (2, 1): f = build_hypergeometric_formula(func) r = carryout_plan(f, ops).replace(hyper, hyperexpand_special) if not r.has(hyper): return r + p # Try to find a formula in our collection formula = _collection.lookup_origin(func) # Now try a lerch phi formula if formula is None: formula = try_lerchphi(func) if formula is None: debug(' Could not find an origin. ', 'Will return answer in terms of ' 'simpler hypergeometric functions.') formula = build_hypergeometric_formula(func) debug(' Found an origin: ', formula.closed_form, ' ', formula.func) # We need to find the operators that convert formula into func. ops += devise_plan(func, formula.func, z0) # Now carry out the plan. r = carryout_plan(formula, ops) + p return powdenest(r, polar=True).replace(hyper, hyperexpand_special) def devise_plan_meijer(fro, to, z): """ Find operators to convert G-function ``fro`` into G-function ``to``. It is assumed that fro and to have the same signatures, and that in fact any corresponding pair of parameters differs by integers, and a direct path is possible. I.e. if there are parameters a1 b1 c1 and a2 b2 c2 it is assumed that a1 can be shifted to a2, etc. The only thing this routine determines is the order of shifts to apply, nothing clever will be tried. It is also assumed that fro is suitable. Examples ======== >>> from sympy.simplify.hyperexpand import (devise_plan_meijer, ... G_Function) >>> from sympy.abc import z Empty plan: >>> devise_plan_meijer(G_Function([1], [2], [3], [4]), ... G_Function([1], [2], [3], [4]), z) [] Very simple plans: >>> devise_plan_meijer(G_Function([0], [], [], []), ... G_Function([1], [], [], []), z) [<Increment upper a index #0 of [0], [], [], [].>] >>> devise_plan_meijer(G_Function([0], [], [], []), ... G_Function([-1], [], [], []), z) [<Decrement upper a=0.>] >>> devise_plan_meijer(G_Function([], [1], [], []), ... G_Function([], [2], [], []), z) [<Increment lower a index #0 of [], [1], [], [].>] Slightly more complicated plans: >>> devise_plan_meijer(G_Function([0], [], [], []), ... G_Function([2], [], [], []), z) [<Increment upper a index #0 of [1], [], [], [].>, <Increment upper a index #0 of [0], [], [], [].>] >>> devise_plan_meijer(G_Function([0], [], [0], []), ... G_Function([-1], [], [1], []), z) [<Increment upper b=0.>, <Decrement upper a=0.>] Order matters: >>> devise_plan_meijer(G_Function([0], [], [0], []), ... G_Function([1], [], [1], []), z) [<Increment upper a index #0 of [0], [], [1], [].>, <Increment upper b=0.>] """ # TODO for now, we use the following simple heuristic: inverse-shift # when possible, shift otherwise. Give up if we cannot make progress. def try_shift(f, t, shifter, diff, counter): """ Try to apply ``shifter`` in order to bring some element in ``f`` nearer to its counterpart in ``to``. ``diff`` is +/- 1 and determines the effect of ``shifter``. Counter is a list of elements blocking the shift. Return an operator if change was possible, else None. """ for idx, (a, b) in enumerate(zip(f, t)): if ( (a - b).is_integer and (b - a)/diff > 0 and all(a != x for x in counter)): sh = shifter(idx) f[idx] += diff return sh fan = list(fro.an) fap = list(fro.ap) fbm = list(fro.bm) fbq = list(fro.bq) ops = [] change = True while change: change = False op = try_shift(fan, to.an, lambda i: MeijerUnShiftB(fan, fap, fbm, fbq, i, z), 1, fbm + fbq) if op is not None: ops += [op] change = True continue op = try_shift(fap, to.ap, lambda i: MeijerUnShiftD(fan, fap, fbm, fbq, i, z), 1, fbm + fbq) if op is not None: ops += [op] change = True continue op = try_shift(fbm, to.bm, lambda i: MeijerUnShiftA(fan, fap, fbm, fbq, i, z), -1, fan + fap) if op is not None: ops += [op] change = True continue op = try_shift(fbq, to.bq, lambda i: MeijerUnShiftC(fan, fap, fbm, fbq, i, z), -1, fan + fap) if op is not None: ops += [op] change = True continue op = try_shift(fan, to.an, lambda i: MeijerShiftB(fan[i]), -1, []) if op is not None: ops += [op] change = True continue op = try_shift(fap, to.ap, lambda i: MeijerShiftD(fap[i]), -1, []) if op is not None: ops += [op] change = True continue op = try_shift(fbm, to.bm, lambda i: MeijerShiftA(fbm[i]), 1, []) if op is not None: ops += [op] change = True continue op = try_shift(fbq, to.bq, lambda i: MeijerShiftC(fbq[i]), 1, []) if op is not None: ops += [op] change = True continue if fan != list(to.an) or fap != list(to.ap) or fbm != list(to.bm) or \ fbq != list(to.bq): raise NotImplementedError('Could not devise plan.') ops.reverse() return ops _meijercollection = None def _meijergexpand(func, z0, allow_hyper=False, rewrite='default', place=None): """ Try to find an expression for the Meijer G function specified by the G_Function ``func``. If ``allow_hyper`` is True, then returning an expression in terms of hypergeometric functions is allowed. Currently this just does Slater's theorem. If expansions exist both at zero and at infinity, ``place`` can be set to ``0`` or ``zoo`` for the preferred choice. """ global _meijercollection if _meijercollection is None: _meijercollection = MeijerFormulaCollection() if rewrite == 'default': rewrite = None func0 = func debug('Try to expand Meijer G function corresponding to ', func) # We will play games with analytic continuation - rather use a fresh symbol z = Dummy('z') func, ops = reduce_order_meijer(func) if ops: debug(' Reduced order to ', func) else: debug(' Could not reduce order.') # Try to find a direct formula f = _meijercollection.lookup_origin(func) if f is not None: debug(' Found a Meijer G formula: ', f.func) ops += devise_plan_meijer(f.func, func, z) # Now carry out the plan. C = apply_operators(f.C.subs(f.z, z), ops, make_derivative_operator(f.M.subs(f.z, z), z)) C = C.applyfunc(make_simp(z)) r = C*f.B.subs(f.z, z) r = r[0].subs(z, z0) return powdenest(r, polar=True) debug(" Could not find a direct formula. Trying Slater's theorem.") # TODO the following would be possible: # *) Paired Index Theorems # *) PFD Duplication # (See Kelly Roach's paper for details on either.) # # TODO Also, we tend to create combinations of gamma functions that can be # simplified. def can_do(pbm, pap): """ Test if slater applies. """ for i in pbm: if len(pbm[i]) > 1: l = 0 if i in pap: l = len(pap[i]) if l + 1 < len(pbm[i]): return False return True def do_slater(an, bm, ap, bq, z, zfinal): # zfinal is the value that will eventually be substituted for z. # We pass it to _hyperexpand to improve performance. func = G_Function(an, bm, ap, bq) _, pbm, pap, _ = func.compute_buckets() if not can_do(pbm, pap): return S(0), False cond = len(an) + len(ap) < len(bm) + len(bq) if len(an) + len(ap) == len(bm) + len(bq): cond = abs(z) < 1 if cond is False: return S(0), False res = S(0) for m in pbm: if len(pbm[m]) == 1: bh = pbm[m][0] fac = 1 bo = list(bm) bo.remove(bh) for bj in bo: fac *= gamma(bj - bh) for aj in an: fac *= gamma(1 + bh - aj) for bj in bq: fac /= gamma(1 + bh - bj) for aj in ap: fac /= gamma(aj - bh) nap = [1 + bh - a for a in list(an) + list(ap)] nbq = [1 + bh - b for b in list(bo) + list(bq)] k = polar_lift(S(-1)**(len(ap) - len(bm))) harg = k*zfinal # NOTE even though k "is" +-1, this has to be t/k instead of # t*k ... we are using polar numbers for consistency! premult = (t/k)**bh hyp = _hyperexpand(Hyper_Function(nap, nbq), harg, ops, t, premult, bh, rewrite=None) res += fac * hyp else: b_ = pbm[m][0] ki = [bi - b_ for bi in pbm[m][1:]] u = len(ki) li = [ai - b_ for ai in pap[m][:u + 1]] bo = list(bm) for b in pbm[m]: bo.remove(b) ao = list(ap) for a in pap[m][:u]: ao.remove(a) lu = li[-1] di = [l - k for (l, k) in zip(li, ki)] # We first work out the integrand: s = Dummy('s') integrand = z**s for b in bm: if not Mod(b, 1) and b.is_Number: b = int(round(b)) integrand *= gamma(b - s) for a in an: integrand *= gamma(1 - a + s) for b in bq: integrand /= gamma(1 - b + s) for a in ap: integrand /= gamma(a - s) # Now sum the finitely many residues: # XXX This speeds up some cases - is it a good idea? integrand = expand_func(integrand) for r in range(int(round(lu))): resid = residue(integrand, s, b_ + r) resid = apply_operators(resid, ops, lambda f: z*f.diff(z)) res -= resid # Now the hypergeometric term. au = b_ + lu k = polar_lift(S(-1)**(len(ao) + len(bo) + 1)) harg = k*zfinal premult = (t/k)**au nap = [1 + au - a for a in list(an) + list(ap)] + [1] nbq = [1 + au - b for b in list(bm) + list(bq)] hyp = _hyperexpand(Hyper_Function(nap, nbq), harg, ops, t, premult, au, rewrite=None) C = S(-1)**(lu)/factorial(lu) for i in range(u): C *= S(-1)**di[i]/rf(lu - li[i] + 1, di[i]) for a in an: C *= gamma(1 - a + au) for b in bo: C *= gamma(b - au) for a in ao: C /= gamma(a - au) for b in bq: C /= gamma(1 - b + au) res += C*hyp return res, cond t = Dummy('t') slater1, cond1 = do_slater(func.an, func.bm, func.ap, func.bq, z, z0) def tr(l): return [1 - x for x in l] for op in ops: op._poly = Poly(op._poly.subs({z: 1/t, _x: -_x}), _x) slater2, cond2 = do_slater(tr(func.bm), tr(func.an), tr(func.bq), tr(func.ap), t, 1/z0) slater1 = powdenest(slater1.subs(z, z0), polar=True) slater2 = powdenest(slater2.subs(t, 1/z0), polar=True) if not isinstance(cond2, bool): cond2 = cond2.subs(t, 1/z) m = func(z) if m.delta > 0 or \ (m.delta == 0 and len(m.ap) == len(m.bq) and (re(m.nu) < -1) is not False and polar_lift(z0) == polar_lift(1)): # The condition delta > 0 means that the convergence region is # connected. Any expression we find can be continued analytically # to the entire convergence region. # The conditions delta==0, p==q, re(nu) < -1 imply that G is continuous # on the positive reals, so the values at z=1 agree. if cond1 is not False: cond1 = True if cond2 is not False: cond2 = True if cond1 is True: slater1 = slater1.rewrite(rewrite or 'nonrep') else: slater1 = slater1.rewrite(rewrite or 'nonrepsmall') if cond2 is True: slater2 = slater2.rewrite(rewrite or 'nonrep') else: slater2 = slater2.rewrite(rewrite or 'nonrepsmall') if cond1 is not False and cond2 is not False: # If one condition is False, there is no choice. if place == 0: cond2 = False if place == zoo: cond1 = False if not isinstance(cond1, bool): cond1 = cond1.subs(z, z0) if not isinstance(cond2, bool): cond2 = cond2.subs(z, z0) def weight(expr, cond): if cond is True: c0 = 0 elif cond is False: c0 = 1 else: c0 = 2 if expr.has(oo, zoo, -oo, nan): # XXX this actually should not happen, but consider # S('meijerg(((0, -1/2, 0, -1/2, 1/2), ()), ((0,), # (-1/2, -1/2, -1/2, -1)), exp_polar(I*pi))/4') c0 = 3 return (c0, expr.count(hyper), expr.count_ops()) w1 = weight(slater1, cond1) w2 = weight(slater2, cond2) if min(w1, w2) <= (0, 1, oo): if w1 < w2: return slater1 else: return slater2 if max(w1[0], w2[0]) <= 1 and max(w1[1], w2[1]) <= 1: return Piecewise((slater1, cond1), (slater2, cond2), (func0(z0), True)) # We couldn't find an expression without hypergeometric functions. # TODO it would be helpful to give conditions under which the integral # is known to diverge. r = Piecewise((slater1, cond1), (slater2, cond2), (func0(z0), True)) if r.has(hyper) and not allow_hyper: debug(' Could express using hypergeometric functions, ' 'but not allowed.') if not r.has(hyper) or allow_hyper: return r return func0(z0) def hyperexpand(f, allow_hyper=False, rewrite='default', place=None): """ Expand hypergeometric functions. If allow_hyper is True, allow partial simplification (that is a result different from input, but still containing hypergeometric functions). If a G-function has expansions both at zero and at infinity, ``place`` can be set to ``0`` or ``zoo`` to indicate the preferred choice. Examples ======== >>> from sympy.simplify.hyperexpand import hyperexpand >>> from sympy.functions import hyper >>> from sympy.abc import z >>> hyperexpand(hyper([], [], z)) exp(z) Non-hyperegeometric parts of the expression and hypergeometric expressions that are not recognised are left unchanged: >>> hyperexpand(1 + hyper([1, 1, 1], [], z)) hyper((1, 1, 1), (), z) + 1 """ f = sympify(f) def do_replace(ap, bq, z): r = _hyperexpand(Hyper_Function(ap, bq), z, rewrite=rewrite) if r is None: return hyper(ap, bq, z) else: return r def do_meijer(ap, bq, z): r = _meijergexpand(G_Function(ap[0], ap[1], bq[0], bq[1]), z, allow_hyper, rewrite=rewrite, place=place) if not r.has(nan, zoo, oo, -oo): return r return f.replace(hyper, do_replace).replace(meijerg, do_meijer)

2c9caed05a79054370733a32acdcd80c3e22caf51eeb7c4fe64b19db94103f4f

from __future__ import print_function, division from collections import defaultdict from sympy.core import (Basic, S, Add, Mul, Pow, Symbol, sympify, expand_mul, expand_func, Function, Dummy, Expr, factor_terms, expand_power_exp) from sympy.core.compatibility import iterable, ordered, range, as_int from sympy.core.evaluate import global_evaluate from sympy.core.function import expand_log, count_ops, _mexpand, _coeff_isneg, nfloat from sympy.core.numbers import Float, I, pi, Rational, Integer from sympy.core.rules import Transform from sympy.core.sympify import _sympify from sympy.functions import gamma, exp, sqrt, log, exp_polar, piecewise_fold from sympy.functions.combinatorial.factorials import CombinatorialFunction from sympy.functions.elementary.complexes import unpolarify from sympy.functions.elementary.exponential import ExpBase from sympy.functions.elementary.hyperbolic import HyperbolicFunction from sympy.functions.elementary.integers import ceiling from sympy.functions.elementary.trigonometric import TrigonometricFunction from sympy.functions.special.bessel import besselj, besseli, besselk, jn, bessely from sympy.polys import together, cancel, factor from sympy.simplify.combsimp import combsimp from sympy.simplify.cse_opts import sub_pre, sub_post from sympy.simplify.powsimp import powsimp from sympy.simplify.radsimp import radsimp, fraction from sympy.simplify.sqrtdenest import sqrtdenest from sympy.simplify.trigsimp import trigsimp, exptrigsimp from sympy.utilities.iterables import has_variety import mpmath def separatevars(expr, symbols=[], dict=False, force=False): """ Separates variables in an expression, if possible. By default, it separates with respect to all symbols in an expression and collects constant coefficients that are independent of symbols. If dict=True then the separated terms will be returned in a dictionary keyed to their corresponding symbols. By default, all symbols in the expression will appear as keys; if symbols are provided, then all those symbols will be used as keys, and any terms in the expression containing other symbols or non-symbols will be returned keyed to the string 'coeff'. (Passing None for symbols will return the expression in a dictionary keyed to 'coeff'.) If force=True, then bases of powers will be separated regardless of assumptions on the symbols involved. Notes ===== The order of the factors is determined by Mul, so that the separated expressions may not necessarily be grouped together. Although factoring is necessary to separate variables in some expressions, it is not necessary in all cases, so one should not count on the returned factors being factored. Examples ======== >>> from sympy.abc import x, y, z, alpha >>> from sympy import separatevars, sin >>> separatevars((x*y)**y) (x*y)**y >>> separatevars((x*y)**y, force=True) x**y*y**y >>> e = 2*x**2*z*sin(y)+2*z*x**2 >>> separatevars(e) 2*x**2*z*(sin(y) + 1) >>> separatevars(e, symbols=(x, y), dict=True) {'coeff': 2*z, x: x**2, y: sin(y) + 1} >>> separatevars(e, [x, y, alpha], dict=True) {'coeff': 2*z, alpha: 1, x: x**2, y: sin(y) + 1} If the expression is not really separable, or is only partially separable, separatevars will do the best it can to separate it by using factoring. >>> separatevars(x + x*y - 3*x**2) -x*(3*x - y - 1) If the expression is not separable then expr is returned unchanged or (if dict=True) then None is returned. >>> eq = 2*x + y*sin(x) >>> separatevars(eq) == eq True >>> separatevars(2*x + y*sin(x), symbols=(x, y), dict=True) == None True """ expr = sympify(expr) if dict: return _separatevars_dict(_separatevars(expr, force), symbols) else: return _separatevars(expr, force) def _separatevars(expr, force): if len(expr.free_symbols) == 1: return expr # don't destroy a Mul since much of the work may already be done if expr.is_Mul: args = list(expr.args) changed = False for i, a in enumerate(args): args[i] = separatevars(a, force) changed = changed or args[i] != a if changed: expr = expr.func(*args) return expr # get a Pow ready for expansion if expr.is_Pow: expr = Pow(separatevars(expr.base, force=force), expr.exp) # First try other expansion methods expr = expr.expand(mul=False, multinomial=False, force=force) _expr, reps = posify(expr) if force else (expr, {}) expr = factor(_expr).subs(reps) if not expr.is_Add: return expr # Find any common coefficients to pull out args = list(expr.args) commonc = args[0].args_cnc(cset=True, warn=False)[0] for i in args[1:]: commonc &= i.args_cnc(cset=True, warn=False)[0] commonc = Mul(*commonc) commonc = commonc.as_coeff_Mul()[1] # ignore constants commonc_set = commonc.args_cnc(cset=True, warn=False)[0] # remove them for i, a in enumerate(args): c, nc = a.args_cnc(cset=True, warn=False) c = c - commonc_set args[i] = Mul(*c)*Mul(*nc) nonsepar = Add(*args) if len(nonsepar.free_symbols) > 1: _expr = nonsepar _expr, reps = posify(_expr) if force else (_expr, {}) _expr = (factor(_expr)).subs(reps) if not _expr.is_Add: nonsepar = _expr return commonc*nonsepar def _separatevars_dict(expr, symbols): if symbols: if not all((t.is_Atom for t in symbols)): raise ValueError("symbols must be Atoms.") symbols = list(symbols) elif symbols is None: return {'coeff': expr} else: symbols = list(expr.free_symbols) if not symbols: return None ret = dict(((i, []) for i in symbols + ['coeff'])) for i in Mul.make_args(expr): expsym = i.free_symbols intersection = set(symbols).intersection(expsym) if len(intersection) > 1: return None if len(intersection) == 0: # There are no symbols, so it is part of the coefficient ret['coeff'].append(i) else: ret[intersection.pop()].append(i) # rebuild for k, v in ret.items(): ret[k] = Mul(*v) return ret def _is_sum_surds(p): args = p.args if p.is_Add else [p] for y in args: if not ((y**2).is_Rational and y.is_real): return False return True def posify(eq): """Return eq (with generic symbols made positive) and a dictionary containing the mapping between the old and new symbols. Any symbol that has positive=None will be replaced with a positive dummy symbol having the same name. This replacement will allow more symbolic processing of expressions, especially those involving powers and logarithms. A dictionary that can be sent to subs to restore eq to its original symbols is also returned. >>> from sympy import posify, Symbol, log, solve >>> from sympy.abc import x >>> posify(x + Symbol('p', positive=True) + Symbol('n', negative=True)) (_x + n + p, {_x: x}) >>> eq = 1/x >>> log(eq).expand() log(1/x) >>> log(posify(eq)[0]).expand() -log(_x) >>> p, rep = posify(eq) >>> log(p).expand().subs(rep) -log(x) It is possible to apply the same transformations to an iterable of expressions: >>> eq = x**2 - 4 >>> solve(eq, x) [-2, 2] >>> eq_x, reps = posify([eq, x]); eq_x [_x**2 - 4, _x] >>> solve(*eq_x) [2] """ eq = sympify(eq) if iterable(eq): f = type(eq) eq = list(eq) syms = set() for e in eq: syms = syms.union(e.atoms(Symbol)) reps = {} for s in syms: reps.update(dict((v, k) for k, v in posify(s)[1].items())) for i, e in enumerate(eq): eq[i] = e.subs(reps) return f(eq), {r: s for s, r in reps.items()} reps = dict([(s, Dummy(s.name, positive=True)) for s in eq.free_symbols if s.is_positive is None]) eq = eq.subs(reps) return eq, {r: s for s, r in reps.items()} def hypersimp(f, k): """Given combinatorial term f(k) simplify its consecutive term ratio i.e. f(k+1)/f(k). The input term can be composed of functions and integer sequences which have equivalent representation in terms of gamma special function. The algorithm performs three basic steps: 1. Rewrite all functions in terms of gamma, if possible. 2. Rewrite all occurrences of gamma in terms of products of gamma and rising factorial with integer, absolute constant exponent. 3. Perform simplification of nested fractions, powers and if the resulting expression is a quotient of polynomials, reduce their total degree. If f(k) is hypergeometric then as result we arrive with a quotient of polynomials of minimal degree. Otherwise None is returned. For more information on the implemented algorithm refer to: 1. W. Koepf, Algorithms for m-fold Hypergeometric Summation, Journal of Symbolic Computation (1995) 20, 399-417 """ f = sympify(f) g = f.subs(k, k + 1) / f g = g.rewrite(gamma) g = expand_func(g) g = powsimp(g, deep=True, combine='exp') if g.is_rational_function(k): return simplify(g, ratio=S.Infinity) else: return None def hypersimilar(f, g, k): """Returns True if 'f' and 'g' are hyper-similar. Similarity in hypergeometric sense means that a quotient of f(k) and g(k) is a rational function in k. This procedure is useful in solving recurrence relations. For more information see hypersimp(). """ f, g = list(map(sympify, (f, g))) h = (f/g).rewrite(gamma) h = h.expand(func=True, basic=False) return h.is_rational_function(k) def signsimp(expr, evaluate=None): """Make all Add sub-expressions canonical wrt sign. If an Add subexpression, ``a``, can have a sign extracted, as determined by could_extract_minus_sign, it is replaced with Mul(-1, a, evaluate=False). This allows signs to be extracted from powers and products. Examples ======== >>> from sympy import signsimp, exp, symbols >>> from sympy.abc import x, y >>> i = symbols('i', odd=True) >>> n = -1 + 1/x >>> n/x/(-n)**2 - 1/n/x (-1 + 1/x)/(x*(1 - 1/x)**2) - 1/(x*(-1 + 1/x)) >>> signsimp(_) 0 >>> x*n + x*-n x*(-1 + 1/x) + x*(1 - 1/x) >>> signsimp(_) 0 Since powers automatically handle leading signs >>> (-2)**i -2**i signsimp can be used to put the base of a power with an integer exponent into canonical form: >>> n**i (-1 + 1/x)**i By default, signsimp doesn't leave behind any hollow simplification: if making an Add canonical wrt sign didn't change the expression, the original Add is restored. If this is not desired then the keyword ``evaluate`` can be set to False: >>> e = exp(y - x) >>> signsimp(e) == e True >>> signsimp(e, evaluate=False) exp(-(x - y)) """ if evaluate is None: evaluate = global_evaluate[0] expr = sympify(expr) if not isinstance(expr, Expr) or expr.is_Atom: return expr e = sub_post(sub_pre(expr)) if not isinstance(e, Expr) or e.is_Atom: return e if e.is_Add: return e.func(*[signsimp(a, evaluate) for a in e.args]) if evaluate: e = e.xreplace({m: -(-m) for m in e.atoms(Mul) if -(-m) != m}) return e def simplify(expr, ratio=1.7, measure=count_ops, rational=False, inverse=False): """Simplifies the given expression. Simplification is not a well defined term and the exact strategies this function tries can change in the future versions of SymPy. If your algorithm relies on "simplification" (whatever it is), try to determine what you need exactly - is it powsimp()?, radsimp()?, together()?, logcombine()?, or something else? And use this particular function directly, because those are well defined and thus your algorithm will be robust. Nonetheless, especially for interactive use, or when you don't know anything about the structure of the expression, simplify() tries to apply intelligent heuristics to make the input expression "simpler". For example: >>> from sympy import simplify, cos, sin >>> from sympy.abc import x, y >>> a = (x + x**2)/(x*sin(y)**2 + x*cos(y)**2) >>> a (x**2 + x)/(x*sin(y)**2 + x*cos(y)**2) >>> simplify(a) x + 1 Note that we could have obtained the same result by using specific simplification functions: >>> from sympy import trigsimp, cancel >>> trigsimp(a) (x**2 + x)/x >>> cancel(_) x + 1 In some cases, applying :func:`simplify` may actually result in some more complicated expression. The default ``ratio=1.7`` prevents more extreme cases: if (result length)/(input length) > ratio, then input is returned unmodified. The ``measure`` parameter lets you specify the function used to determine how complex an expression is. The function should take a single argument as an expression and return a number such that if expression ``a`` is more complex than expression ``b``, then ``measure(a) > measure(b)``. The default measure function is :func:`count_ops`, which returns the total number of operations in the expression. For example, if ``ratio=1``, ``simplify`` output can't be longer than input. :: >>> from sympy import sqrt, simplify, count_ops, oo >>> root = 1/(sqrt(2)+3) Since ``simplify(root)`` would result in a slightly longer expression, root is returned unchanged instead:: >>> simplify(root, ratio=1) == root True If ``ratio=oo``, simplify will be applied anyway:: >>> count_ops(simplify(root, ratio=oo)) > count_ops(root) True Note that the shortest expression is not necessary the simplest, so setting ``ratio`` to 1 may not be a good idea. Heuristically, the default value ``ratio=1.7`` seems like a reasonable choice. You can easily define your own measure function based on what you feel should represent the "size" or "complexity" of the input expression. Note that some choices, such as ``lambda expr: len(str(expr))`` may appear to be good metrics, but have other problems (in this case, the measure function may slow down simplify too much for very large expressions). If you don't know what a good metric would be, the default, ``count_ops``, is a good one. For example: >>> from sympy import symbols, log >>> a, b = symbols('a b', positive=True) >>> g = log(a) + log(b) + log(a)*log(1/b) >>> h = simplify(g) >>> h log(a*b**(-log(a) + 1)) >>> count_ops(g) 8 >>> count_ops(h) 5 So you can see that ``h`` is simpler than ``g`` using the count_ops metric. However, we may not like how ``simplify`` (in this case, using ``logcombine``) has created the ``b**(log(1/a) + 1)`` term. A simple way to reduce this would be to give more weight to powers as operations in ``count_ops``. We can do this by using the ``visual=True`` option: >>> print(count_ops(g, visual=True)) 2*ADD + DIV + 4*LOG + MUL >>> print(count_ops(h, visual=True)) 2*LOG + MUL + POW + SUB >>> from sympy import Symbol, S >>> def my_measure(expr): ... POW = Symbol('POW') ... # Discourage powers by giving POW a weight of 10 ... count = count_ops(expr, visual=True).subs(POW, 10) ... # Every other operation gets a weight of 1 (the default) ... count = count.replace(Symbol, type(S.One)) ... return count >>> my_measure(g) 8 >>> my_measure(h) 14 >>> 15./8 > 1.7 # 1.7 is the default ratio True >>> simplify(g, measure=my_measure) -log(a)*log(b) + log(a) + log(b) Note that because ``simplify()`` internally tries many different simplification strategies and then compares them using the measure function, we get a completely different result that is still different from the input expression by doing this. If rational=True, Floats will be recast as Rationals before simplification. If rational=None, Floats will be recast as Rationals but the result will be recast as Floats. If rational=False(default) then nothing will be done to the Floats. If inverse=True, it will be assumed that a composition of inverse functions, such as sin and asin, can be cancelled in any order. For example, ``asin(sin(x))`` will yield ``x`` without checking whether x belongs to the set where this relation is true. The default is False. """ expr = sympify(expr) try: return expr._eval_simplify(ratio=ratio, measure=measure, rational=rational, inverse=inverse) except AttributeError: pass original_expr = expr = signsimp(expr) from sympy.simplify.hyperexpand import hyperexpand from sympy.functions.special.bessel import BesselBase from sympy import Sum, Product if not isinstance(expr, Basic) or not expr.args: # XXX: temporary hack return expr if inverse and expr.has(Function): expr = inversecombine(expr) if not expr.args: # simplified to atomic return expr if not isinstance(expr, (Add, Mul, Pow, ExpBase)): return expr.func(*[simplify(x, ratio=ratio, measure=measure, rational=rational, inverse=inverse) for x in expr.args]) if not expr.is_commutative: expr = nc_simplify(expr) # TODO: Apply different strategies, considering expression pattern: # is it a purely rational function? Is there any trigonometric function?... # See also https://github.com/sympy/sympy/pull/185. def shorter(*choices): '''Return the choice that has the fewest ops. In case of a tie, the expression listed first is selected.''' if not has_variety(choices): return choices[0] return min(choices, key=measure) # rationalize Floats floats = False if rational is not False and expr.has(Float): floats = True expr = nsimplify(expr, rational=True) expr = bottom_up(expr, lambda w: w.normal()) expr = Mul(*powsimp(expr).as_content_primitive()) _e = cancel(expr) expr1 = shorter(_e, _mexpand(_e).cancel()) # issue 6829 expr2 = shorter(together(expr, deep=True), together(expr1, deep=True)) if ratio is S.Infinity: expr = expr2 else: expr = shorter(expr2, expr1, expr) if not isinstance(expr, Basic): # XXX: temporary hack return expr expr = factor_terms(expr, sign=False) # hyperexpand automatically only works on hypergeometric terms expr = hyperexpand(expr) expr = piecewise_fold(expr) if expr.has(BesselBase): expr = besselsimp(expr) if expr.has(TrigonometricFunction, HyperbolicFunction): expr = trigsimp(expr, deep=True) if expr.has(log): expr = shorter(expand_log(expr, deep=True), logcombine(expr)) if expr.has(CombinatorialFunction, gamma): # expression with gamma functions or non-integer arguments is # automatically passed to gammasimp expr = combsimp(expr) if expr.has(Sum): expr = sum_simplify(expr) if expr.has(Product): expr = product_simplify(expr) from sympy.physics.units import Quantity from sympy.physics.units.util import quantity_simplify if expr.has(Quantity): expr = quantity_simplify(expr) short = shorter(powsimp(expr, combine='exp', deep=True), powsimp(expr), expr) short = shorter(short, cancel(short)) short = shorter(short, factor_terms(short), expand_power_exp(expand_mul(short))) if short.has(TrigonometricFunction, HyperbolicFunction, ExpBase): short = exptrigsimp(short) # get rid of hollow 2-arg Mul factorization hollow_mul = Transform( lambda x: Mul(*x.args), lambda x: x.is_Mul and len(x.args) == 2 and x.args[0].is_Number and x.args[1].is_Add and x.is_commutative) expr = short.xreplace(hollow_mul) numer, denom = expr.as_numer_denom() if denom.is_Add: n, d = fraction(radsimp(1/denom, symbolic=False, max_terms=1)) if n is not S.One: expr = (numer*n).expand()/d if expr.could_extract_minus_sign(): n, d = fraction(expr) if d != 0: expr = signsimp(-n/(-d)) if measure(expr) > ratio*measure(original_expr): expr = original_expr # restore floats if floats and rational is None: expr = nfloat(expr, exponent=False) return expr def sum_simplify(s): """Main function for Sum simplification""" from sympy.concrete.summations import Sum from sympy.core.function import expand terms = Add.make_args(expand(s)) s_t = [] # Sum Terms o_t = [] # Other Terms for term in terms: if isinstance(term, Mul): other = 1 sum_terms = [] if not term.has(Sum): o_t.append(term) continue mul_terms = Mul.make_args(term) for mul_term in mul_terms: if isinstance(mul_term, Sum): r = mul_term._eval_simplify() sum_terms.extend(Add.make_args(r)) else: other = other * mul_term if len(sum_terms): #some simplification may have happened #use if so s_t.append(Mul(*sum_terms) * other) else: o_t.append(other) elif isinstance(term, Sum): #as above, we need to turn this into an add list r = term._eval_simplify() s_t.extend(Add.make_args(r)) else: o_t.append(term) result = Add(sum_combine(s_t), *o_t) return result def sum_combine(s_t): """Helper function for Sum simplification Attempts to simplify a list of sums, by combining limits / sum function's returns the simplified sum """ from sympy.concrete.summations import Sum used = [False] * len(s_t) for method in range(2): for i, s_term1 in enumerate(s_t): if not used[i]: for j, s_term2 in enumerate(s_t): if not used[j] and i != j: temp = sum_add(s_term1, s_term2, method) if isinstance(temp, Sum) or isinstance(temp, Mul): s_t[i] = temp s_term1 = s_t[i] used[j] = True result = S.Zero for i, s_term in enumerate(s_t): if not used[i]: result = Add(result, s_term) return result def factor_sum(self, limits=None, radical=False, clear=False, fraction=False, sign=True): """Helper function for Sum simplification if limits is specified, "self" is the inner part of a sum Returns the sum with constant factors brought outside """ from sympy.core.exprtools import factor_terms from sympy.concrete.summations import Sum result = self.function if limits is None else self limits = self.limits if limits is None else limits #avoid any confusion w/ as_independent if result == 0: return S.Zero #get the summation variables sum_vars = set([limit.args[0] for limit in limits]) #finally we try to factor out any common terms #and remove the from the sum if independent retv = factor_terms(result, radical=radical, clear=clear, fraction=fraction, sign=sign) #avoid doing anything bad if not result.is_commutative: return Sum(result, *limits) i, d = retv.as_independent(*sum_vars) if isinstance(retv, Add): return i * Sum(1, *limits) + Sum(d, *limits) else: return i * Sum(d, *limits) def sum_add(self, other, method=0): """Helper function for Sum simplification""" from sympy.concrete.summations import Sum from sympy import Mul #we know this is something in terms of a constant * a sum #so we temporarily put the constants inside for simplification #then simplify the result def __refactor(val): args = Mul.make_args(val) sumv = next(x for x in args if isinstance(x, Sum)) constant = Mul(*[x for x in args if x != sumv]) return Sum(constant * sumv.function, *sumv.limits) if isinstance(self, Mul): rself = __refactor(self) else: rself = self if isinstance(other, Mul): rother = __refactor(other) else: rother = other if type(rself) == type(rother): if method == 0: if rself.limits == rother.limits: return factor_sum(Sum(rself.function + rother.function, *rself.limits)) elif method == 1: if simplify(rself.function - rother.function) == 0: if len(rself.limits) == len(rother.limits) == 1: i = rself.limits[0][0] x1 = rself.limits[0][1] y1 = rself.limits[0][2] j = rother.limits[0][0] x2 = rother.limits[0][1] y2 = rother.limits[0][2] if i == j: if x2 == y1 + 1: return factor_sum(Sum(rself.function, (i, x1, y2))) elif x1 == y2 + 1: return factor_sum(Sum(rself.function, (i, x2, y1))) return Add(self, other) def product_simplify(s): """Main function for Product simplification""" from sympy.concrete.products import Product terms = Mul.make_args(s) p_t = [] # Product Terms o_t = [] # Other Terms for term in terms: if isinstance(term, Product): p_t.append(term) else: o_t.append(term) used = [False] * len(p_t) for method in range(2): for i, p_term1 in enumerate(p_t): if not used[i]: for j, p_term2 in enumerate(p_t): if not used[j] and i != j: if isinstance(product_mul(p_term1, p_term2, method), Product): p_t[i] = product_mul(p_term1, p_term2, method) used[j] = True result = Mul(*o_t) for i, p_term in enumerate(p_t): if not used[i]: result = Mul(result, p_term) return result def product_mul(self, other, method=0): """Helper function for Product simplification""" from sympy.concrete.products import Product if type(self) == type(other): if method == 0: if self.limits == other.limits: return Product(self.function * other.function, *self.limits) elif method == 1: if simplify(self.function - other.function) == 0: if len(self.limits) == len(other.limits) == 1: i = self.limits[0][0] x1 = self.limits[0][1] y1 = self.limits[0][2] j = other.limits[0][0] x2 = other.limits[0][1] y2 = other.limits[0][2] if i == j: if x2 == y1 + 1: return Product(self.function, (i, x1, y2)) elif x1 == y2 + 1: return Product(self.function, (i, x2, y1)) return Mul(self, other) def _nthroot_solve(p, n, prec): """ helper function for ``nthroot`` It denests ``p**Rational(1, n)`` using its minimal polynomial """ from sympy.polys.numberfields import _minimal_polynomial_sq from sympy.solvers import solve while n % 2 == 0: p = sqrtdenest(sqrt(p)) n = n // 2 if n == 1: return p pn = p**Rational(1, n) x = Symbol('x') f = _minimal_polynomial_sq(p, n, x) if f is None: return None sols = solve(f, x) for sol in sols: if abs(sol - pn).n() < 1./10**prec: sol = sqrtdenest(sol) if _mexpand(sol**n) == p: return sol def logcombine(expr, force=False): """ Takes logarithms and combines them using the following rules: - log(x) + log(y) == log(x*y) if both are not negative - a*log(x) == log(x**a) if x is positive and a is real If ``force`` is True then the assumptions above will be assumed to hold if there is no assumption already in place on a quantity. For example, if ``a`` is imaginary or the argument negative, force will not perform a combination but if ``a`` is a symbol with no assumptions the change will take place. Examples ======== >>> from sympy import Symbol, symbols, log, logcombine, I >>> from sympy.abc import a, x, y, z >>> logcombine(a*log(x) + log(y) - log(z)) a*log(x) + log(y) - log(z) >>> logcombine(a*log(x) + log(y) - log(z), force=True) log(x**a*y/z) >>> x,y,z = symbols('x,y,z', positive=True) >>> a = Symbol('a', real=True) >>> logcombine(a*log(x) + log(y) - log(z)) log(x**a*y/z) The transformation is limited to factors and/or terms that contain logs, so the result depends on the initial state of expansion: >>> eq = (2 + 3*I)*log(x) >>> logcombine(eq, force=True) == eq True >>> logcombine(eq.expand(), force=True) log(x**2) + I*log(x**3) See Also ======== posify: replace all symbols with symbols having positive assumptions sympy.core.function.expand_log: expand the logarithms of products and powers; the opposite of logcombine """ def f(rv): if not (rv.is_Add or rv.is_Mul): return rv def gooda(a): # bool to tell whether the leading ``a`` in ``a*log(x)`` # could appear as log(x**a) return (a is not S.NegativeOne and # -1 *could* go, but we disallow (a.is_real or force and a.is_real is not False)) def goodlog(l): # bool to tell whether log ``l``'s argument can combine with others a = l.args[0] return a.is_positive or force and a.is_nonpositive is not False other = [] logs = [] log1 = defaultdict(list) for a in Add.make_args(rv): if isinstance(a, log) and goodlog(a): log1[()].append(([], a)) elif not a.is_Mul: other.append(a) else: ot = [] co = [] lo = [] for ai in a.args: if ai.is_Rational and ai < 0: ot.append(S.NegativeOne) co.append(-ai) elif isinstance(ai, log) and goodlog(ai): lo.append(ai) elif gooda(ai): co.append(ai) else: ot.append(ai) if len(lo) > 1: logs.append((ot, co, lo)) elif lo: log1[tuple(ot)].append((co, lo[0])) else: other.append(a) # if there is only one log at each coefficient and none have # an exponent to place inside the log then there is nothing to do if not logs and all(len(log1[k]) == 1 and log1[k][0] == [] for k in log1): return rv # collapse multi-logs as far as possible in a canonical way # TODO: see if x*log(a)+x*log(a)*log(b) -> x*log(a)*(1+log(b))? # -- in this case, it's unambiguous, but if it were were a log(c) in # each term then it's arbitrary whether they are grouped by log(a) or # by log(c). So for now, just leave this alone; it's probably better to # let the user decide for o, e, l in logs: l = list(ordered(l)) e = log(l.pop(0).args[0]**Mul(*e)) while l: li = l.pop(0) e = log(li.args[0]**e) c, l = Mul(*o), e if isinstance(l, log): # it should be, but check to be sure log1[(c,)].append(([], l)) else: other.append(c*l) # logs that have the same coefficient can multiply for k in list(log1.keys()): log1[Mul(*k)] = log(logcombine(Mul(*[ l.args[0]**Mul(*c) for c, l in log1.pop(k)]), force=force), evaluate=False) # logs that have oppositely signed coefficients can divide for k in ordered(list(log1.keys())): if not k in log1: # already popped as -k continue if -k in log1: # figure out which has the minus sign; the one with # more op counts should be the one num, den = k, -k if num.count_ops() > den.count_ops(): num, den = den, num other.append( num*log(log1.pop(num).args[0]/log1.pop(den).args[0], evaluate=False)) else: other.append(k*log1.pop(k)) return Add(*other) return bottom_up(expr, f) def inversecombine(expr): """Simplify the composition of a function and its inverse. No attention is paid to whether the inverse is a left inverse or a right inverse; thus, the result will in general not be equivalent to the original expression. Examples ======== >>> from sympy.simplify.simplify import inversecombine >>> from sympy import asin, sin, log, exp >>> from sympy.abc import x >>> inversecombine(asin(sin(x))) x >>> inversecombine(2*log(exp(3*x))) 6*x """ def f(rv): if rv.is_Function and hasattr(rv, "inverse"): if (len(rv.args) == 1 and len(rv.args[0].args) == 1 and isinstance(rv.args[0], rv.inverse(argindex=1))): rv = rv.args[0].args[0] return rv return bottom_up(expr, f) def walk(e, *target): """iterate through the args that are the given types (target) and return a list of the args that were traversed; arguments that are not of the specified types are not traversed. Examples ======== >>> from sympy.simplify.simplify import walk >>> from sympy import Min, Max >>> from sympy.abc import x, y, z >>> list(walk(Min(x, Max(y, Min(1, z))), Min)) [Min(x, Max(y, Min(1, z)))] >>> list(walk(Min(x, Max(y, Min(1, z))), Min, Max)) [Min(x, Max(y, Min(1, z))), Max(y, Min(1, z)), Min(1, z)] See Also ======== bottom_up """ if isinstance(e, target): yield e for i in e.args: for w in walk(i, *target): yield w def bottom_up(rv, F, atoms=False, nonbasic=False): """Apply ``F`` to all expressions in an expression tree from the bottom up. If ``atoms`` is True, apply ``F`` even if there are no args; if ``nonbasic`` is True, try to apply ``F`` to non-Basic objects. """ try: if rv.args: args = tuple([bottom_up(a, F, atoms, nonbasic) for a in rv.args]) if args != rv.args: rv = rv.func(*args) rv = F(rv) elif atoms: rv = F(rv) except AttributeError: if nonbasic: try: rv = F(rv) except TypeError: pass return rv def besselsimp(expr): """ Simplify bessel-type functions. This routine tries to simplify bessel-type functions. Currently it only works on the Bessel J and I functions, however. It works by looking at all such functions in turn, and eliminating factors of "I" and "-1" (actually their polar equivalents) in front of the argument. Then, functions of half-integer order are rewritten using strigonometric functions and functions of integer order (> 1) are rewritten using functions of low order. Finally, if the expression was changed, compute factorization of the result with factor(). >>> from sympy import besselj, besseli, besselsimp, polar_lift, I, S >>> from sympy.abc import z, nu >>> besselsimp(besselj(nu, z*polar_lift(-1))) exp(I*pi*nu)*besselj(nu, z) >>> besselsimp(besseli(nu, z*polar_lift(-I))) exp(-I*pi*nu/2)*besselj(nu, z) >>> besselsimp(besseli(S(-1)/2, z)) sqrt(2)*cosh(z)/(sqrt(pi)*sqrt(z)) >>> besselsimp(z*besseli(0, z) + z*(besseli(2, z))/2 + besseli(1, z)) 3*z*besseli(0, z)/2 """ # TODO # - better algorithm? # - simplify (cos(pi*b)*besselj(b,z) - besselj(-b,z))/sin(pi*b) ... # - use contiguity relations? def replacer(fro, to, factors): factors = set(factors) def repl(nu, z): if factors.intersection(Mul.make_args(z)): return to(nu, z) return fro(nu, z) return repl def torewrite(fro, to): def tofunc(nu, z): return fro(nu, z).rewrite(to) return tofunc def tominus(fro): def tofunc(nu, z): return exp(I*pi*nu)*fro(nu, exp_polar(-I*pi)*z) return tofunc orig_expr = expr ifactors = [I, exp_polar(I*pi/2), exp_polar(-I*pi/2)] expr = expr.replace( besselj, replacer(besselj, torewrite(besselj, besseli), ifactors)) expr = expr.replace( besseli, replacer(besseli, torewrite(besseli, besselj), ifactors)) minusfactors = [-1, exp_polar(I*pi)] expr = expr.replace( besselj, replacer(besselj, tominus(besselj), minusfactors)) expr = expr.replace( besseli, replacer(besseli, tominus(besseli), minusfactors)) z0 = Dummy('z') def expander(fro): def repl(nu, z): if (nu % 1) == S(1)/2: return simplify(trigsimp(unpolarify( fro(nu, z0).rewrite(besselj).rewrite(jn).expand( func=True)).subs(z0, z))) elif nu.is_Integer and nu > 1: return fro(nu, z).expand(func=True) return fro(nu, z) return repl expr = expr.replace(besselj, expander(besselj)) expr = expr.replace(bessely, expander(bessely)) expr = expr.replace(besseli, expander(besseli)) expr = expr.replace(besselk, expander(besselk)) if expr != orig_expr: expr = expr.factor() return expr def nthroot(expr, n, max_len=4, prec=15): """ compute a real nth-root of a sum of surds Parameters ========== expr : sum of surds n : integer max_len : maximum number of surds passed as constants to ``nsimplify`` Algorithm ========= First ``nsimplify`` is used to get a candidate root; if it is not a root the minimal polynomial is computed; the answer is one of its roots. Examples ======== >>> from sympy.simplify.simplify import nthroot >>> from sympy import Rational, sqrt >>> nthroot(90 + 34*sqrt(7), 3) sqrt(7) + 3 """ expr = sympify(expr) n = sympify(n) p = expr**Rational(1, n) if not n.is_integer: return p if not _is_sum_surds(expr): return p surds = [] coeff_muls = [x.as_coeff_Mul() for x in expr.args] for x, y in coeff_muls: if not x.is_rational: return p if y is S.One: continue if not (y.is_Pow and y.exp == S.Half and y.base.is_integer): return p surds.append(y) surds.sort() surds = surds[:max_len] if expr < 0 and n % 2 == 1: p = (-expr)**Rational(1, n) a = nsimplify(p, constants=surds) res = a if _mexpand(a**n) == _mexpand(-expr) else p return -res a = nsimplify(p, constants=surds) if _mexpand(a) is not _mexpand(p) and _mexpand(a**n) == _mexpand(expr): return _mexpand(a) expr = _nthroot_solve(expr, n, prec) if expr is None: return p return expr def nsimplify(expr, constants=(), tolerance=None, full=False, rational=None, rational_conversion='base10'): """ Find a simple representation for a number or, if there are free symbols or if rational=True, then replace Floats with their Rational equivalents. If no change is made and rational is not False then Floats will at least be converted to Rationals. For numerical expressions, a simple formula that numerically matches the given numerical expression is sought (and the input should be possible to evalf to a precision of at least 30 digits). Optionally, a list of (rationally independent) constants to include in the formula may be given. A lower tolerance may be set to find less exact matches. If no tolerance is given then the least precise value will set the tolerance (e.g. Floats default to 15 digits of precision, so would be tolerance=10**-15). With full=True, a more extensive search is performed (this is useful to find simpler numbers when the tolerance is set low). When converting to rational, if rational_conversion='base10' (the default), then convert floats to rationals using their base-10 (string) representation. When rational_conversion='exact' it uses the exact, base-2 representation. Examples ======== >>> from sympy import nsimplify, sqrt, GoldenRatio, exp, I, exp, pi >>> nsimplify(4/(1+sqrt(5)), [GoldenRatio]) -2 + 2*GoldenRatio >>> nsimplify((1/(exp(3*pi*I/5)+1))) 1/2 - I*sqrt(sqrt(5)/10 + 1/4) >>> nsimplify(I**I, [pi]) exp(-pi/2) >>> nsimplify(pi, tolerance=0.01) 22/7 >>> nsimplify(0.333333333333333, rational=True, rational_conversion='exact') 6004799503160655/18014398509481984 >>> nsimplify(0.333333333333333, rational=True) 1/3 See Also ======== sympy.core.function.nfloat """ try: return sympify(as_int(expr)) except (TypeError, ValueError): pass expr = sympify(expr).xreplace({ Float('inf'): S.Infinity, Float('-inf'): S.NegativeInfinity, }) if expr is S.Infinity or expr is S.NegativeInfinity: return expr if rational or expr.free_symbols: return _real_to_rational(expr, tolerance, rational_conversion) # SymPy's default tolerance for Rationals is 15; other numbers may have # lower tolerances set, so use them to pick the largest tolerance if None # was given if tolerance is None: tolerance = 10**-min([15] + [mpmath.libmp.libmpf.prec_to_dps(n._prec) for n in expr.atoms(Float)]) # XXX should prec be set independent of tolerance or should it be computed # from tolerance? prec = 30 bprec = int(prec*3.33) constants_dict = {} for constant in constants: constant = sympify(constant) v = constant.evalf(prec) if not v.is_Float: raise ValueError("constants must be real-valued") constants_dict[str(constant)] = v._to_mpmath(bprec) exprval = expr.evalf(prec, chop=True) re, im = exprval.as_real_imag() # safety check to make sure that this evaluated to a number if not (re.is_Number and im.is_Number): return expr def nsimplify_real(x): orig = mpmath.mp.dps xv = x._to_mpmath(bprec) try: # We'll be happy with low precision if a simple fraction if not (tolerance or full): mpmath.mp.dps = 15 rat = mpmath.pslq([xv, 1]) if rat is not None: return Rational(-int(rat[1]), int(rat[0])) mpmath.mp.dps = prec newexpr = mpmath.identify(xv, constants=constants_dict, tol=tolerance, full=full) if not newexpr: raise ValueError if full: newexpr = newexpr[0] expr = sympify(newexpr) if x and not expr: # don't let x become 0 raise ValueError if expr.is_finite is False and not xv in [mpmath.inf, mpmath.ninf]: raise ValueError return expr finally: # even though there are returns above, this is executed # before leaving mpmath.mp.dps = orig try: if re: re = nsimplify_real(re) if im: im = nsimplify_real(im) except ValueError: if rational is None: return _real_to_rational(expr, rational_conversion=rational_conversion) return expr rv = re + im*S.ImaginaryUnit # if there was a change or rational is explicitly not wanted # return the value, else return the Rational representation if rv != expr or rational is False: return rv return _real_to_rational(expr, rational_conversion=rational_conversion) def _real_to_rational(expr, tolerance=None, rational_conversion='base10'): """ Replace all reals in expr with rationals. Examples ======== >>> from sympy import Rational >>> from sympy.simplify.simplify import _real_to_rational >>> from sympy.abc import x >>> _real_to_rational(.76 + .1*x**.5) sqrt(x)/10 + 19/25 If rational_conversion='base10', this uses the base-10 string. If rational_conversion='exact', the exact, base-2 representation is used. >>> _real_to_rational(0.333333333333333, rational_conversion='exact') 6004799503160655/18014398509481984 >>> _real_to_rational(0.333333333333333) 1/3 """ expr = _sympify(expr) inf = Float('inf') p = expr reps = {} reduce_num = None if tolerance is not None and tolerance < 1: reduce_num = ceiling(1/tolerance) for fl in p.atoms(Float): key = fl if reduce_num is not None: r = Rational(fl).limit_denominator(reduce_num) elif (tolerance is not None and tolerance >= 1 and fl.is_Integer is False): r = Rational(tolerance*round(fl/tolerance) ).limit_denominator(int(tolerance)) else: if rational_conversion == 'exact': r = Rational(fl) reps[key] = r continue elif rational_conversion != 'base10': raise ValueError("rational_conversion must be 'base10' or 'exact'") r = nsimplify(fl, rational=False) # e.g. log(3).n() -> log(3) instead of a Rational if fl and not r: r = Rational(fl) elif not r.is_Rational: if fl == inf or fl == -inf: r = S.ComplexInfinity elif fl < 0: fl = -fl d = Pow(10, int((mpmath.log(fl)/mpmath.log(10)))) r = -Rational(str(fl/d))*d elif fl > 0: d = Pow(10, int((mpmath.log(fl)/mpmath.log(10)))) r = Rational(str(fl/d))*d else: r = Integer(0) reps[key] = r return p.subs(reps, simultaneous=True) def clear_coefficients(expr, rhs=S.Zero): """Return `p, r` where `p` is the expression obtained when Rational additive and multiplicative coefficients of `expr` have been stripped away in a naive fashion (i.e. without simplification). The operations needed to remove the coefficients will be applied to `rhs` and returned as `r`. Examples ======== >>> from sympy.simplify.simplify import clear_coefficients >>> from sympy.abc import x, y >>> from sympy import Dummy >>> expr = 4*y*(6*x + 3) >>> clear_coefficients(expr - 2) (y*(2*x + 1), 1/6) When solving 2 or more expressions like `expr = a`, `expr = b`, etc..., it is advantageous to provide a Dummy symbol for `rhs` and simply replace it with `a`, `b`, etc... in `r`. >>> rhs = Dummy('rhs') >>> clear_coefficients(expr, rhs) (y*(2*x + 1), _rhs/12) >>> _[1].subs(rhs, 2) 1/6 """ was = None free = expr.free_symbols if expr.is_Rational: return (S.Zero, rhs - expr) while expr and was != expr: was = expr m, expr = ( expr.as_content_primitive() if free else factor_terms(expr).as_coeff_Mul(rational=True)) rhs /= m c, expr = expr.as_coeff_Add(rational=True) rhs -= c expr = signsimp(expr, evaluate = False) if _coeff_isneg(expr): expr = -expr rhs = -rhs return expr, rhs def nc_simplify(expr, deep=True): ''' Simplify a non-commutative expression composed of multiplication and raising to a power by grouping repeated subterms into one power. Priority is given to simplifications that give the fewest number of arguments in the end (for example, in a*b*a*b*c*a*b*c simplifying to (a*b)**2*c*a*b*c gives 5 arguments while a*b*(a*b*c)**2 has 3). If `expr` is a sum of such terms, the sum of the simplified terms is returned. Keyword argument `deep` controls whether or not subexpressions nested deeper inside the main expression are simplified. See examples below. Setting `deep` to `False` can save time on nested expressions that don't need simplifying on all levels. Examples ======== >>> from sympy import symbols >>> from sympy.simplify.simplify import nc_simplify >>> a, b, c = symbols("a b c", commutative=False) >>> nc_simplify(a*b*a*b*c*a*b*c) a*b*(a*b*c)**2 >>> expr = a**2*b*a**4*b*a**4 >>> nc_simplify(expr) a**2*(b*a**4)**2 >>> nc_simplify(a*b*a*b*c**2*(a*b)**2*c**2) ((a*b)**2*c**2)**2 >>> nc_simplify(a*b*a*b + 2*a*c*a**2*c*a**2*c*a) (a*b)**2 + 2*(a*c*a)**3 >>> nc_simplify(b**-1*a**-1*(a*b)**2) a*b >>> nc_simplify(a**-1*b**-1*c*a) (b*a)**(-1)*c*a >>> expr = (a*b*a*b)**2*a*c*a*c >>> nc_simplify(expr) (a*b)**4*(a*c)**2 >>> nc_simplify(expr, deep=False) (a*b*a*b)**2*(a*c)**2 ''' from sympy.matrices.expressions import (MatrixExpr, MatAdd, MatMul, MatPow, MatrixSymbol) from sympy.core.exprtools import factor_nc if isinstance(expr, MatrixExpr): expr = expr.doit(inv_expand=False) _Add, _Mul, _Pow, _Symbol = MatAdd, MatMul, MatPow, MatrixSymbol else: _Add, _Mul, _Pow, _Symbol = Add, Mul, Pow, Symbol # =========== Auxiliary functions ======================== def _overlaps(args): # Calculate a list of lists m such that m[i][j] contains the lengths # of all possible overlaps between args[:i+1] and args[i+1+j:]. # An overlap is a suffix of the prefix that matches a prefix # of the suffix. # For example, let expr=c*a*b*a*b*a*b*a*b. Then m[3][0] contains # the lengths of overlaps of c*a*b*a*b with a*b*a*b. The overlaps # are a*b*a*b, a*b and the empty word so that m[3][0]=[4,2,0]. # All overlaps rather than only the longest one are recorded # because this information helps calculate other overlap lengths. m = [[([1, 0] if a == args[0] else [0]) for a in args[1:]]] for i in range(1, len(args)): overlaps = [] j = 0 for j in range(len(args) - i - 1): overlap = [] for v in m[i-1][j+1]: if j + i + 1 + v < len(args) and args[i] == args[j+i+1+v]: overlap.append(v + 1) overlap += [0] overlaps.append(overlap) m.append(overlaps) return m def _reduce_inverses(_args): # replace consecutive negative powers by an inverse # of a product of positive powers, e.g. a**-1*b**-1*c # will simplify to (a*b)**-1*c; # return that new args list and the number of negative # powers in it (inv_tot) inv_tot = 0 # total number of inverses inverses = [] args = [] for arg in _args: if isinstance(arg, _Pow) and arg.args[1] < 0: inverses = [arg**-1] + inverses inv_tot += 1 else: if len(inverses) == 1: args.append(inverses[0]**-1) elif len(inverses) > 1: args.append(_Pow(_Mul(*inverses), -1)) inv_tot -= len(inverses) - 1 inverses = [] args.append(arg) if inverses: args.append(_Pow(_Mul(*inverses), -1)) inv_tot -= len(inverses) - 1 return inv_tot, tuple(args) def get_score(s): # compute the number of arguments of s # (including in nested expressions) overall # but ignore exponents if isinstance(s, _Pow): return get_score(s.args[0]) elif isinstance(s, (_Add, _Mul)): return sum([get_score(a) for a in s.args]) return 1 def compare(s, alt_s): # compare two possible simplifications and return a # "better" one if s != alt_s and get_score(alt_s) < get_score(s): return alt_s return s # ======================================================== if not isinstance(expr, (_Add, _Mul, _Pow)) or expr.is_commutative: return expr args = expr.args[:] if isinstance(expr, _Pow): if deep: return _Pow(nc_simplify(args[0]), args[1]).doit() else: return expr elif isinstance(expr, _Add): return _Add(*[nc_simplify(a, deep=deep) for a in args]).doit() else: # get the non-commutative part c_args, args = expr.args_cnc() com_coeff = Mul(*c_args) if com_coeff != 1: return com_coeff*nc_simplify(expr/com_coeff, deep=deep) inv_tot, args = _reduce_inverses(args) # if most arguments are negative, work with the inverse # of the expression, e.g. a**-1*b*a**-1*c**-1 will become # (c*a*b**-1*a)**-1 at the end so can work with c*a*b**-1*a invert = False if inv_tot > len(args)/2: invert = True args = [a**-1 for a in args[::-1]] if deep: args = tuple(nc_simplify(a) for a in args) m = _overlaps(args) # simps will be {subterm: end} where `end` is the ending # index of a sequence of repetitions of subterm; # this is for not wasting time with subterms that are part # of longer, already considered sequences simps = {} post = 1 pre = 1 # the simplification coefficient is the number of # arguments by which contracting a given sequence # would reduce the word; e.g. in a*b*a*b*c*a*b*c, # contracting a*b*a*b to (a*b)**2 removes 3 arguments # while a*b*c*a*b*c to (a*b*c)**2 removes 6. It's # better to contract the latter so simplification # with a maximum simplification coefficient will be chosen max_simp_coeff = 0 simp = None # information about future simplification for i in range(1, len(args)): simp_coeff = 0 l = 0 # length of a subterm p = 0 # the power of a subterm if i < len(args) - 1: rep = m[i][0] start = i # starting index of the repeated sequence end = i+1 # ending index of the repeated sequence if i == len(args)-1 or rep == [0]: # no subterm is repeated at this stage, at least as # far as the arguments are concerned - there may be # a repetition if powers are taken into account if (isinstance(args[i], _Pow) and not isinstance(args[i].args[0], _Symbol)): subterm = args[i].args[0].args l = len(subterm) if args[i-l:i] == subterm: # e.g. a*b in a*b*(a*b)**2 is not repeated # in args (= [a, b, (a*b)**2]) but it # can be matched here p += 1 start -= l if args[i+1:i+1+l] == subterm: # e.g. a*b in (a*b)**2*a*b p += 1 end += l if p: p += args[i].args[1] else: continue else: l = rep[0] # length of the longest repeated subterm at this point start -= l - 1 subterm = args[start:end] p = 2 end += l if subterm in simps and simps[subterm] >= start: # the subterm is part of a sequence that # has already been considered continue # count how many times it's repeated while end < len(args): if l in m[end-1][0]: p += 1 end += l elif isinstance(args[end], _Pow) and args[end].args[0].args == subterm: # for cases like a*b*a*b*(a*b)**2*a*b p += args[end].args[1] end += 1 else: break # see if another match can be made, e.g. # for b*a**2 in b*a**2*b*a**3 or a*b in # a**2*b*a*b pre_exp = 0 pre_arg = 1 if start - l >= 0 and args[start-l+1:start] == subterm[1:]: if isinstance(subterm[0], _Pow): pre_arg = subterm[0].args[0] exp = subterm[0].args[1] else: pre_arg = subterm[0] exp = 1 if isinstance(args[start-l], _Pow) and args[start-l].args[0] == pre_arg: pre_exp = args[start-l].args[1] - exp start -= l p += 1 elif args[start-l] == pre_arg: pre_exp = 1 - exp start -= l p += 1 post_exp = 0 post_arg = 1 if end + l - 1 < len(args) and args[end:end+l-1] == subterm[:-1]: if isinstance(subterm[-1], _Pow): post_arg = subterm[-1].args[0] exp = subterm[-1].args[1] else: post_arg = subterm[-1] exp = 1 if isinstance(args[end+l-1], _Pow) and args[end+l-1].args[0] == post_arg: post_exp = args[end+l-1].args[1] - exp end += l p += 1 elif args[end+l-1] == post_arg: post_exp = 1 - exp end += l p += 1 # Consider a*b*a**2*b*a**2*b*a: # b*a**2 is explicitly repeated, but note # that in this case a*b*a is also repeated # so there are two possible simplifications: # a*(b*a**2)**3*a**-1 or (a*b*a)**3 # The latter is obviously simpler. # But in a*b*a**2*b**2*a**2 the simplifications are # a*(b*a**2)**2 and (a*b*a)**3*a in which case # it's better to stick with the shorter subterm if post_exp and exp % 2 == 0 and start > 0: exp = exp/2 _pre_exp = 1 _post_exp = 1 if isinstance(args[start-1], _Pow) and args[start-1].args[0] == post_arg: _post_exp = post_exp + exp _pre_exp = args[start-1].args[1] - exp elif args[start-1] == post_arg: _post_exp = post_exp + exp _pre_exp = 1 - exp if _pre_exp == 0 or _post_exp == 0: if not pre_exp: start -= 1 post_exp = _post_exp pre_exp = _pre_exp pre_arg = post_arg subterm = (post_arg**exp,) + subterm[:-1] + (post_arg**exp,) simp_coeff += end-start if post_exp: simp_coeff -= 1 if pre_exp: simp_coeff -= 1 simps[subterm] = end if simp_coeff > max_simp_coeff: max_simp_coeff = simp_coeff simp = (start, _Mul(*subterm), p, end, l) pre = pre_arg**pre_exp post = post_arg**post_exp if simp: subterm = _Pow(nc_simplify(simp[1], deep=deep), simp[2]) pre = nc_simplify(_Mul(*args[:simp[0]])*pre, deep=deep) post = post*nc_simplify(_Mul(*args[simp[3]:]), deep=deep) simp = pre*subterm*post if pre != 1 or post != 1: # new simplifications may be possible but no need # to recurse over arguments simp = nc_simplify(simp, deep=False) else: simp = _Mul(*args) if invert: simp = _Pow(simp, -1) # see if factor_nc(expr) is simplified better if not isinstance(expr, MatrixExpr): f_expr = factor_nc(expr) if f_expr != expr: alt_simp = nc_simplify(f_expr, deep=deep) simp = compare(simp, alt_simp) else: simp = simp.doit(inv_expand=False) return simp

914aa2ad8da7ec17f8bc81adfac36ab59dd59ff027f746751179165a3a635f5e

from __future__ import print_function, division from collections import defaultdict from sympy import SYMPY_DEBUG from sympy.core import expand_power_base, sympify, Add, S, Mul, Derivative, Pow, symbols, expand_mul from sympy.core.add import _unevaluated_Add from sympy.core.compatibility import iterable, ordered, default_sort_key from sympy.core.evaluate import global_evaluate from sympy.core.exprtools import Factors, gcd_terms from sympy.core.function import _mexpand from sympy.core.mul import _keep_coeff, _unevaluated_Mul from sympy.core.numbers import Rational from sympy.functions import exp, sqrt, log from sympy.polys import gcd from sympy.simplify.sqrtdenest import sqrtdenest def collect(expr, syms, func=None, evaluate=None, exact=False, distribute_order_term=True): """ Collect additive terms of an expression. This function collects additive terms of an expression with respect to a list of expression up to powers with rational exponents. By the term symbol here are meant arbitrary expressions, which can contain powers, products, sums etc. In other words symbol is a pattern which will be searched for in the expression's terms. The input expression is not expanded by :func:`collect`, so user is expected to provide an expression is an appropriate form. This makes :func:`collect` more predictable as there is no magic happening behind the scenes. However, it is important to note, that powers of products are converted to products of powers using the :func:`expand_power_base` function. There are two possible types of output. First, if ``evaluate`` flag is set, this function will return an expression with collected terms or else it will return a dictionary with expressions up to rational powers as keys and collected coefficients as values. Examples ======== >>> from sympy import S, collect, expand, factor, Wild >>> from sympy.abc import a, b, c, x, y, z This function can collect symbolic coefficients in polynomials or rational expressions. It will manage to find all integer or rational powers of collection variable:: >>> collect(a*x**2 + b*x**2 + a*x - b*x + c, x) c + x**2*(a + b) + x*(a - b) The same result can be achieved in dictionary form:: >>> d = collect(a*x**2 + b*x**2 + a*x - b*x + c, x, evaluate=False) >>> d[x**2] a + b >>> d[x] a - b >>> d[S.One] c You can also work with multivariate polynomials. However, remember that this function is greedy so it will care only about a single symbol at time, in specification order:: >>> collect(x**2 + y*x**2 + x*y + y + a*y, [x, y]) x**2*(y + 1) + x*y + y*(a + 1) Also more complicated expressions can be used as patterns:: >>> from sympy import sin, log >>> collect(a*sin(2*x) + b*sin(2*x), sin(2*x)) (a + b)*sin(2*x) >>> collect(a*x*log(x) + b*(x*log(x)), x*log(x)) x*(a + b)*log(x) You can use wildcards in the pattern:: >>> w = Wild('w1') >>> collect(a*x**y - b*x**y, w**y) x**y*(a - b) It is also possible to work with symbolic powers, although it has more complicated behavior, because in this case power's base and symbolic part of the exponent are treated as a single symbol:: >>> collect(a*x**c + b*x**c, x) a*x**c + b*x**c >>> collect(a*x**c + b*x**c, x**c) x**c*(a + b) However if you incorporate rationals to the exponents, then you will get well known behavior:: >>> collect(a*x**(2*c) + b*x**(2*c), x**c) x**(2*c)*(a + b) Note also that all previously stated facts about :func:`collect` function apply to the exponential function, so you can get:: >>> from sympy import exp >>> collect(a*exp(2*x) + b*exp(2*x), exp(x)) (a + b)*exp(2*x) If you are interested only in collecting specific powers of some symbols then set ``exact`` flag in arguments:: >>> collect(a*x**7 + b*x**7, x, exact=True) a*x**7 + b*x**7 >>> collect(a*x**7 + b*x**7, x**7, exact=True) x**7*(a + b) You can also apply this function to differential equations, where derivatives of arbitrary order can be collected. Note that if you collect with respect to a function or a derivative of a function, all derivatives of that function will also be collected. Use ``exact=True`` to prevent this from happening:: >>> from sympy import Derivative as D, collect, Function >>> f = Function('f') (x) >>> collect(a*D(f,x) + b*D(f,x), D(f,x)) (a + b)*Derivative(f(x), x) >>> collect(a*D(D(f,x),x) + b*D(D(f,x),x), f) (a + b)*Derivative(f(x), (x, 2)) >>> collect(a*D(D(f,x),x) + b*D(D(f,x),x), D(f,x), exact=True) a*Derivative(f(x), (x, 2)) + b*Derivative(f(x), (x, 2)) >>> collect(a*D(f,x) + b*D(f,x) + a*f + b*f, f) (a + b)*f(x) + (a + b)*Derivative(f(x), x) Or you can even match both derivative order and exponent at the same time:: >>> collect(a*D(D(f,x),x)**2 + b*D(D(f,x),x)**2, D(f,x)) (a + b)*Derivative(f(x), (x, 2))**2 Finally, you can apply a function to each of the collected coefficients. For example you can factorize symbolic coefficients of polynomial:: >>> f = expand((x + a + 1)**3) >>> collect(f, x, factor) x**3 + 3*x**2*(a + 1) + 3*x*(a + 1)**2 + (a + 1)**3 .. note:: Arguments are expected to be in expanded form, so you might have to call :func:`expand` prior to calling this function. See Also ======== collect_const, collect_sqrt, rcollect """ expr = sympify(expr) syms = list(syms) if iterable(syms) else [syms] if evaluate is None: evaluate = global_evaluate[0] def make_expression(terms): product = [] for term, rat, sym, deriv in terms: if deriv is not None: var, order = deriv while order > 0: term, order = Derivative(term, var), order - 1 if sym is None: if rat is S.One: product.append(term) else: product.append(Pow(term, rat)) else: product.append(Pow(term, rat*sym)) return Mul(*product) def parse_derivative(deriv): # scan derivatives tower in the input expression and return # underlying function and maximal differentiation order expr, sym, order = deriv.expr, deriv.variables[0], 1 for s in deriv.variables[1:]: if s == sym: order += 1 else: raise NotImplementedError( 'Improve MV Derivative support in collect') while isinstance(expr, Derivative): s0 = expr.variables[0] for s in expr.variables: if s != s0: raise NotImplementedError( 'Improve MV Derivative support in collect') if s0 == sym: expr, order = expr.expr, order + len(expr.variables) else: break return expr, (sym, Rational(order)) def parse_term(expr): """Parses expression expr and outputs tuple (sexpr, rat_expo, sym_expo, deriv) where: - sexpr is the base expression - rat_expo is the rational exponent that sexpr is raised to - sym_expo is the symbolic exponent that sexpr is raised to - deriv contains the derivatives the the expression for example, the output of x would be (x, 1, None, None) the output of 2**x would be (2, 1, x, None) """ rat_expo, sym_expo = S.One, None sexpr, deriv = expr, None if expr.is_Pow: if isinstance(expr.base, Derivative): sexpr, deriv = parse_derivative(expr.base) else: sexpr = expr.base if expr.exp.is_Number: rat_expo = expr.exp else: coeff, tail = expr.exp.as_coeff_Mul() if coeff.is_Number: rat_expo, sym_expo = coeff, tail else: sym_expo = expr.exp elif isinstance(expr, exp): arg = expr.args[0] if arg.is_Rational: sexpr, rat_expo = S.Exp1, arg elif arg.is_Mul: coeff, tail = arg.as_coeff_Mul(rational=True) sexpr, rat_expo = exp(tail), coeff elif isinstance(expr, Derivative): sexpr, deriv = parse_derivative(expr) return sexpr, rat_expo, sym_expo, deriv def parse_expression(terms, pattern): """Parse terms searching for a pattern. terms is a list of tuples as returned by parse_terms; pattern is an expression treated as a product of factors """ pattern = Mul.make_args(pattern) if len(terms) < len(pattern): # pattern is longer than matched product # so no chance for positive parsing result return None else: pattern = [parse_term(elem) for elem in pattern] terms = terms[:] # need a copy elems, common_expo, has_deriv = [], None, False for elem, e_rat, e_sym, e_ord in pattern: if elem.is_Number and e_rat == 1 and e_sym is None: # a constant is a match for everything continue for j in range(len(terms)): if terms[j] is None: continue term, t_rat, t_sym, t_ord = terms[j] # keeping track of whether one of the terms had # a derivative or not as this will require rebuilding # the expression later if t_ord is not None: has_deriv = True if (term.match(elem) is not None and (t_sym == e_sym or t_sym is not None and e_sym is not None and t_sym.match(e_sym) is not None)): if exact is False: # we don't have to be exact so find common exponent # for both expression's term and pattern's element expo = t_rat / e_rat if common_expo is None: # first time common_expo = expo else: # common exponent was negotiated before so # there is no chance for a pattern match unless # common and current exponents are equal if common_expo != expo: common_expo = 1 else: # we ought to be exact so all fields of # interest must match in every details if e_rat != t_rat or e_ord != t_ord: continue # found common term so remove it from the expression # and try to match next element in the pattern elems.append(terms[j]) terms[j] = None break else: # pattern element not found return None return [_f for _f in terms if _f], elems, common_expo, has_deriv if evaluate: if expr.is_Add: o = expr.getO() or 0 expr = expr.func(*[ collect(a, syms, func, True, exact, distribute_order_term) for a in expr.args if a != o]) + o elif expr.is_Mul: return expr.func(*[ collect(term, syms, func, True, exact, distribute_order_term) for term in expr.args]) elif expr.is_Pow: b = collect( expr.base, syms, func, True, exact, distribute_order_term) return Pow(b, expr.exp) syms = [expand_power_base(i, deep=False) for i in syms] order_term = None if distribute_order_term: order_term = expr.getO() if order_term is not None: if order_term.has(*syms): order_term = None else: expr = expr.removeO() summa = [expand_power_base(i, deep=False) for i in Add.make_args(expr)] collected, disliked = defaultdict(list), S.Zero for product in summa: c, nc = product.args_cnc(split_1=False) args = list(ordered(c)) + nc terms = [parse_term(i) for i in args] small_first = True for symbol in syms: if SYMPY_DEBUG: print("DEBUG: parsing of expression %s with symbol %s " % ( str(terms), str(symbol)) ) if isinstance(symbol, Derivative) and small_first: terms = list(reversed(terms)) small_first = not small_first result = parse_expression(terms, symbol) if SYMPY_DEBUG: print("DEBUG: returned %s" % str(result)) if result is not None: if not symbol.is_commutative: raise AttributeError("Can not collect noncommutative symbol") terms, elems, common_expo, has_deriv = result # when there was derivative in current pattern we # will need to rebuild its expression from scratch if not has_deriv: margs = [] for elem in elems: if elem[2] is None: e = elem[1] else: e = elem[1]*elem[2] margs.append(Pow(elem[0], e)) index = Mul(*margs) else: index = make_expression(elems) terms = expand_power_base(make_expression(terms), deep=False) index = expand_power_base(index, deep=False) collected[index].append(terms) break else: # none of the patterns matched disliked += product # add terms now for each key collected = {k: Add(*v) for k, v in collected.items()} if disliked is not S.Zero: collected[S.One] = disliked if order_term is not None: for key, val in collected.items(): collected[key] = val + order_term if func is not None: collected = dict( [(key, func(val)) for key, val in collected.items()]) if evaluate: return Add(*[key*val for key, val in collected.items()]) else: return collected def rcollect(expr, *vars): """ Recursively collect sums in an expression. Examples ======== >>> from sympy.simplify import rcollect >>> from sympy.abc import x, y >>> expr = (x**2*y + x*y + x + y)/(x + y) >>> rcollect(expr, y) (x + y*(x**2 + x + 1))/(x + y) See Also ======== collect, collect_const, collect_sqrt """ if expr.is_Atom or not expr.has(*vars): return expr else: expr = expr.__class__(*[rcollect(arg, *vars) for arg in expr.args]) if expr.is_Add: return collect(expr, vars) else: return expr def collect_sqrt(expr, evaluate=None): """Return expr with terms having common square roots collected together. If ``evaluate`` is False a count indicating the number of sqrt-containing terms will be returned and, if non-zero, the terms of the Add will be returned, else the expression itself will be returned as a single term. If ``evaluate`` is True, the expression with any collected terms will be returned. Note: since I = sqrt(-1), it is collected, too. Examples ======== >>> from sympy import sqrt >>> from sympy.simplify.radsimp import collect_sqrt >>> from sympy.abc import a, b >>> r2, r3, r5 = [sqrt(i) for i in [2, 3, 5]] >>> collect_sqrt(a*r2 + b*r2) sqrt(2)*(a + b) >>> collect_sqrt(a*r2 + b*r2 + a*r3 + b*r3) sqrt(2)*(a + b) + sqrt(3)*(a + b) >>> collect_sqrt(a*r2 + b*r2 + a*r3 + b*r5) sqrt(3)*a + sqrt(5)*b + sqrt(2)*(a + b) If evaluate is False then the arguments will be sorted and returned as a list and a count of the number of sqrt-containing terms will be returned: >>> collect_sqrt(a*r2 + b*r2 + a*r3 + b*r5, evaluate=False) ((sqrt(3)*a, sqrt(5)*b, sqrt(2)*(a + b)), 3) >>> collect_sqrt(a*sqrt(2) + b, evaluate=False) ((b, sqrt(2)*a), 1) >>> collect_sqrt(a + b, evaluate=False) ((a + b,), 0) See Also ======== collect, collect_const, rcollect """ if evaluate is None: evaluate = global_evaluate[0] # this step will help to standardize any complex arguments # of sqrts coeff, expr = expr.as_content_primitive() vars = set() for a in Add.make_args(expr): for m in a.args_cnc()[0]: if m.is_number and ( m.is_Pow and m.exp.is_Rational and m.exp.q == 2 or m is S.ImaginaryUnit): vars.add(m) # we only want radicals, so exclude Number handling; in this case # d will be evaluated d = collect_const(expr, *vars, Numbers=False) hit = expr != d if not evaluate: nrad = 0 # make the evaluated args canonical args = list(ordered(Add.make_args(d))) for i, m in enumerate(args): c, nc = m.args_cnc() for ci in c: # XXX should this be restricted to ci.is_number as above? if ci.is_Pow and ci.exp.is_Rational and ci.exp.q == 2 or \ ci is S.ImaginaryUnit: nrad += 1 break args[i] *= coeff if not (hit or nrad): args = [Add(*args)] return tuple(args), nrad return coeff*d def collect_const(expr, *vars, **kwargs): """A non-greedy collection of terms with similar number coefficients in an Add expr. If ``vars`` is given then only those constants will be targeted. Although any Number can also be targeted, if this is not desired set ``Numbers=False`` and no Float or Rational will be collected. Parameters ========== expr : sympy expression This parameter defines the expression the expression from which terms with similar coefficients are to be collected. A non-Add expression is returned as it is. vars : variable length collection of Numbers, optional Specifies the constants to target for collection. Can be multiple in number. kwargs : ``Numbers`` is the only possible argument to pass. Numbers (default=True) specifies to target all instance of :class:`sympy.core.numbers.Number` class. If ``Numbers=False``, then no Float or Rational will be collected. Returns ======= expr : Expr Returns an expression with similar coefficient terms collected. Examples ======== >>> from sympy import sqrt >>> from sympy.abc import a, s, x, y, z >>> from sympy.simplify.radsimp import collect_const >>> collect_const(sqrt(3) + sqrt(3)*(1 + sqrt(2))) sqrt(3)*(sqrt(2) + 2) >>> collect_const(sqrt(3)*s + sqrt(7)*s + sqrt(3) + sqrt(7)) (sqrt(3) + sqrt(7))*(s + 1) >>> s = sqrt(2) + 2 >>> collect_const(sqrt(3)*s + sqrt(3) + sqrt(7)*s + sqrt(7)) (sqrt(2) + 3)*(sqrt(3) + sqrt(7)) >>> collect_const(sqrt(3)*s + sqrt(3) + sqrt(7)*s + sqrt(7), sqrt(3)) sqrt(7) + sqrt(3)*(sqrt(2) + 3) + sqrt(7)*(sqrt(2) + 2) The collection is sign-sensitive, giving higher precedence to the unsigned values: >>> collect_const(x - y - z) x - (y + z) >>> collect_const(-y - z) -(y + z) >>> collect_const(2*x - 2*y - 2*z, 2) 2*(x - y - z) >>> collect_const(2*x - 2*y - 2*z, -2) 2*x - 2*(y + z) See Also ======== collect, collect_sqrt, rcollect """ if not expr.is_Add: return expr recurse = False Numbers = kwargs.get('Numbers', True) if not vars: recurse = True vars = set() for a in expr.args: for m in Mul.make_args(a): if m.is_number: vars.add(m) else: vars = sympify(vars) if not Numbers: vars = [v for v in vars if not v.is_Number] vars = list(ordered(vars)) for v in vars: terms = defaultdict(list) Fv = Factors(v) for m in Add.make_args(expr): f = Factors(m) q, r = f.div(Fv) if r.is_one: # only accept this as a true factor if # it didn't change an exponent from an Integer # to a non-Integer, e.g. 2/sqrt(2) -> sqrt(2) # -- we aren't looking for this sort of change fwas = f.factors.copy() fnow = q.factors if not any(k in fwas and fwas[k].is_Integer and not fnow[k].is_Integer for k in fnow): terms[v].append(q.as_expr()) continue terms[S.One].append(m) args = [] hit = False uneval = False for k in ordered(terms): v = terms[k] if k is S.One: args.extend(v) continue if len(v) > 1: v = Add(*v) hit = True if recurse and v != expr: vars.append(v) else: v = v[0] # be careful not to let uneval become True unless # it must be because it's going to be more expensive # to rebuild the expression as an unevaluated one if Numbers and k.is_Number and v.is_Add: args.append(_keep_coeff(k, v, sign=True)) uneval = True else: args.append(k*v) if hit: if uneval: expr = _unevaluated_Add(*args) else: expr = Add(*args) if not expr.is_Add: break return expr def radsimp(expr, symbolic=True, max_terms=4): r""" Rationalize the denominator by removing square roots. Note: the expression returned from radsimp must be used with caution since if the denominator contains symbols, it will be possible to make substitutions that violate the assumptions of the simplification process: that for a denominator matching a + b*sqrt(c), a != +/-b*sqrt(c). (If there are no symbols, this assumptions is made valid by collecting terms of sqrt(c) so the match variable ``a`` does not contain ``sqrt(c)``.) If you do not want the simplification to occur for symbolic denominators, set ``symbolic`` to False. If there are more than ``max_terms`` radical terms then the expression is returned unchanged. Examples ======== >>> from sympy import radsimp, sqrt, Symbol, denom, pprint, I >>> from sympy import factor_terms, fraction, signsimp >>> from sympy.simplify.radsimp import collect_sqrt >>> from sympy.abc import a, b, c >>> radsimp(1/(2 + sqrt(2))) (-sqrt(2) + 2)/2 >>> x,y = map(Symbol, 'xy') >>> e = ((2 + 2*sqrt(2))*x + (2 + sqrt(8))*y)/(2 + sqrt(2)) >>> radsimp(e) sqrt(2)*(x + y) No simplification beyond removal of the gcd is done. One might want to polish the result a little, however, by collecting square root terms: >>> r2 = sqrt(2) >>> r5 = sqrt(5) >>> ans = radsimp(1/(y*r2 + x*r2 + a*r5 + b*r5)); pprint(ans) ___ ___ ___ ___ \/ 5 *a + \/ 5 *b - \/ 2 *x - \/ 2 *y ------------------------------------------ 2 2 2 2 5*a + 10*a*b + 5*b - 2*x - 4*x*y - 2*y >>> n, d = fraction(ans) >>> pprint(factor_terms(signsimp(collect_sqrt(n))/d, radical=True)) ___ ___ \/ 5 *(a + b) - \/ 2 *(x + y) ------------------------------------------ 2 2 2 2 5*a + 10*a*b + 5*b - 2*x - 4*x*y - 2*y If radicals in the denominator cannot be removed or there is no denominator, the original expression will be returned. >>> radsimp(sqrt(2)*x + sqrt(2)) sqrt(2)*x + sqrt(2) Results with symbols will not always be valid for all substitutions: >>> eq = 1/(a + b*sqrt(c)) >>> eq.subs(a, b*sqrt(c)) 1/(2*b*sqrt(c)) >>> radsimp(eq).subs(a, b*sqrt(c)) nan If symbolic=False, symbolic denominators will not be transformed (but numeric denominators will still be processed): >>> radsimp(eq, symbolic=False) 1/(a + b*sqrt(c)) """ from sympy.simplify.simplify import signsimp syms = symbols("a:d A:D") def _num(rterms): # return the multiplier that will simplify the expression described # by rterms [(sqrt arg, coeff), ... ] a, b, c, d, A, B, C, D = syms if len(rterms) == 2: reps = dict(list(zip([A, a, B, b], [j for i in rterms for j in i]))) return ( sqrt(A)*a - sqrt(B)*b).xreplace(reps) if len(rterms) == 3: reps = dict(list(zip([A, a, B, b, C, c], [j for i in rterms for j in i]))) return ( (sqrt(A)*a + sqrt(B)*b - sqrt(C)*c)*(2*sqrt(A)*sqrt(B)*a*b - A*a**2 - B*b**2 + C*c**2)).xreplace(reps) elif len(rterms) == 4: reps = dict(list(zip([A, a, B, b, C, c, D, d], [j for i in rterms for j in i]))) return ((sqrt(A)*a + sqrt(B)*b - sqrt(C)*c - sqrt(D)*d)*(2*sqrt(A)*sqrt(B)*a*b - A*a**2 - B*b**2 - 2*sqrt(C)*sqrt(D)*c*d + C*c**2 + D*d**2)*(-8*sqrt(A)*sqrt(B)*sqrt(C)*sqrt(D)*a*b*c*d + A**2*a**4 - 2*A*B*a**2*b**2 - 2*A*C*a**2*c**2 - 2*A*D*a**2*d**2 + B**2*b**4 - 2*B*C*b**2*c**2 - 2*B*D*b**2*d**2 + C**2*c**4 - 2*C*D*c**2*d**2 + D**2*d**4)).xreplace(reps) elif len(rterms) == 1: return sqrt(rterms[0][0]) else: raise NotImplementedError def ispow2(d, log2=False): if not d.is_Pow: return False e = d.exp if e.is_Rational and e.q == 2 or symbolic and denom(e) == 2: return True if log2: q = 1 if e.is_Rational: q = e.q elif symbolic: d = denom(e) if d.is_Integer: q = d if q != 1 and log(q, 2).is_Integer: return True return False def handle(expr): # Handle first reduces to the case # expr = 1/d, where d is an add, or d is base**p/2. # We do this by recursively calling handle on each piece. from sympy.simplify.simplify import nsimplify n, d = fraction(expr) if expr.is_Atom or (d.is_Atom and n.is_Atom): return expr elif not n.is_Atom: n = n.func(*[handle(a) for a in n.args]) return _unevaluated_Mul(n, handle(1/d)) elif n is not S.One: return _unevaluated_Mul(n, handle(1/d)) elif d.is_Mul: return _unevaluated_Mul(*[handle(1/d) for d in d.args]) # By this step, expr is 1/d, and d is not a mul. if not symbolic and d.free_symbols: return expr if ispow2(d): d2 = sqrtdenest(sqrt(d.base))**numer(d.exp) if d2 != d: return handle(1/d2) elif d.is_Pow and (d.exp.is_integer or d.base.is_positive): # (1/d**i) = (1/d)**i return handle(1/d.base)**d.exp if not (d.is_Add or ispow2(d)): return 1/d.func(*[handle(a) for a in d.args]) # handle 1/d treating d as an Add (though it may not be) keep = True # keep changes that are made # flatten it and collect radicals after checking for special # conditions d = _mexpand(d) # did it change? if d.is_Atom: return 1/d # is it a number that might be handled easily? if d.is_number: _d = nsimplify(d) if _d.is_Number and _d.equals(d): return 1/_d while True: # collect similar terms collected = defaultdict(list) for m in Add.make_args(d): # d might have become non-Add p2 = [] other = [] for i in Mul.make_args(m): if ispow2(i, log2=True): p2.append(i.base if i.exp is S.Half else i.base**(2*i.exp)) elif i is S.ImaginaryUnit: p2.append(S.NegativeOne) else: other.append(i) collected[tuple(ordered(p2))].append(Mul(*other)) rterms = list(ordered(list(collected.items()))) rterms = [(Mul(*i), Add(*j)) for i, j in rterms] nrad = len(rterms) - (1 if rterms[0][0] is S.One else 0) if nrad < 1: break elif nrad > max_terms: # there may have been invalid operations leading to this point # so don't keep changes, e.g. this expression is troublesome # in collecting terms so as not to raise the issue of 2834: # r = sqrt(sqrt(5) + 5) # eq = 1/(sqrt(5)*r + 2*sqrt(5)*sqrt(-sqrt(5) + 5) + 5*r) keep = False break if len(rterms) > 4: # in general, only 4 terms can be removed with repeated squaring # but other considerations can guide selection of radical terms # so that radicals are removed if all([x.is_Integer and (y**2).is_Rational for x, y in rterms]): nd, d = rad_rationalize(S.One, Add._from_args( [sqrt(x)*y for x, y in rterms])) n *= nd else: # is there anything else that might be attempted? keep = False break from sympy.simplify.powsimp import powsimp, powdenest num = powsimp(_num(rterms)) n *= num d *= num d = powdenest(_mexpand(d), force=symbolic) if d.is_Atom: break if not keep: return expr return _unevaluated_Mul(n, 1/d) coeff, expr = expr.as_coeff_Add() expr = expr.normal() old = fraction(expr) n, d = fraction(handle(expr)) if old != (n, d): if not d.is_Atom: was = (n, d) n = signsimp(n, evaluate=False) d = signsimp(d, evaluate=False) u = Factors(_unevaluated_Mul(n, 1/d)) u = _unevaluated_Mul(*[k**v for k, v in u.factors.items()]) n, d = fraction(u) if old == (n, d): n, d = was n = expand_mul(n) if d.is_Number or d.is_Add: n2, d2 = fraction(gcd_terms(_unevaluated_Mul(n, 1/d))) if d2.is_Number or (d2.count_ops() <= d.count_ops()): n, d = [signsimp(i) for i in (n2, d2)] if n.is_Mul and n.args[0].is_Number: n = n.func(*n.args) return coeff + _unevaluated_Mul(n, 1/d) def rad_rationalize(num, den): """ Rationalize num/den by removing square roots in the denominator; num and den are sum of terms whose squares are rationals Examples ======== >>> from sympy import sqrt >>> from sympy.simplify.radsimp import rad_rationalize >>> rad_rationalize(sqrt(3), 1 + sqrt(2)/3) (-sqrt(3) + sqrt(6)/3, -7/9) """ if not den.is_Add: return num, den g, a, b = split_surds(den) a = a*sqrt(g) num = _mexpand((a - b)*num) den = _mexpand(a**2 - b**2) return rad_rationalize(num, den) def fraction(expr, exact=False): """Returns a pair with expression's numerator and denominator. If the given expression is not a fraction then this function will return the tuple (expr, 1). This function will not make any attempt to simplify nested fractions or to do any term rewriting at all. If only one of the numerator/denominator pair is needed then use numer(expr) or denom(expr) functions respectively. >>> from sympy import fraction, Rational, Symbol >>> from sympy.abc import x, y >>> fraction(x/y) (x, y) >>> fraction(x) (x, 1) >>> fraction(1/y**2) (1, y**2) >>> fraction(x*y/2) (x*y, 2) >>> fraction(Rational(1, 2)) (1, 2) This function will also work fine with assumptions: >>> k = Symbol('k', negative=True) >>> fraction(x * y**k) (x, y**(-k)) If we know nothing about sign of some exponent and 'exact' flag is unset, then structure this exponent's structure will be analyzed and pretty fraction will be returned: >>> from sympy import exp, Mul >>> fraction(2*x**(-y)) (2, x**y) >>> fraction(exp(-x)) (1, exp(x)) >>> fraction(exp(-x), exact=True) (exp(-x), 1) The `exact` flag will also keep any unevaluated Muls from being evaluated: >>> u = Mul(2, x + 1, evaluate=False) >>> fraction(u) (2*x + 2, 1) >>> fraction(u, exact=True) (2*(x + 1), 1) """ expr = sympify(expr) numer, denom = [], [] for term in Mul.make_args(expr): if term.is_commutative and (term.is_Pow or isinstance(term, exp)): b, ex = term.as_base_exp() if ex.is_negative: if ex is S.NegativeOne: denom.append(b) elif exact: if ex.is_constant(): denom.append(Pow(b, -ex)) else: numer.append(term) else: denom.append(Pow(b, -ex)) elif ex.is_positive: numer.append(term) elif not exact and ex.is_Mul: n, d = term.as_numer_denom() numer.append(n) denom.append(d) else: numer.append(term) elif term.is_Rational: n, d = term.as_numer_denom() numer.append(n) denom.append(d) else: numer.append(term) if exact: return Mul(*numer, evaluate=False), Mul(*denom, evaluate=False) else: return Mul(*numer), Mul(*denom) def numer(expr): return fraction(expr)[0] def denom(expr): return fraction(expr)[1] def fraction_expand(expr, **hints): return expr.expand(frac=True, **hints) def numer_expand(expr, **hints): a, b = fraction(expr) return a.expand(numer=True, **hints) / b def denom_expand(expr, **hints): a, b = fraction(expr) return a / b.expand(denom=True, **hints) expand_numer = numer_expand expand_denom = denom_expand expand_fraction = fraction_expand def split_surds(expr): """ split an expression with terms whose squares are rationals into a sum of terms whose surds squared have gcd equal to g and a sum of terms with surds squared prime with g Examples ======== >>> from sympy import sqrt >>> from sympy.simplify.radsimp import split_surds >>> split_surds(3*sqrt(3) + sqrt(5)/7 + sqrt(6) + sqrt(10) + sqrt(15)) (3, sqrt(2) + sqrt(5) + 3, sqrt(5)/7 + sqrt(10)) """ args = sorted(expr.args, key=default_sort_key) coeff_muls = [x.as_coeff_Mul() for x in args] surds = [x[1]**2 for x in coeff_muls if x[1].is_Pow] surds.sort(key=default_sort_key) g, b1, b2 = _split_gcd(*surds) g2 = g if not b2 and len(b1) >= 2: b1n = [x/g for x in b1] b1n = [x for x in b1n if x != 1] # only a common factor has been factored; split again g1, b1n, b2 = _split_gcd(*b1n) g2 = g*g1 a1v, a2v = [], [] for c, s in coeff_muls: if s.is_Pow and s.exp == S.Half: s1 = s.base if s1 in b1: a1v.append(c*sqrt(s1/g2)) else: a2v.append(c*s) else: a2v.append(c*s) a = Add(*a1v) b = Add(*a2v) return g2, a, b def _split_gcd(*a): """ split the list of integers ``a`` into a list of integers, ``a1`` having ``g = gcd(a1)``, and a list ``a2`` whose elements are not divisible by ``g``. Returns ``g, a1, a2`` Examples ======== >>> from sympy.simplify.radsimp import _split_gcd >>> _split_gcd(55, 35, 22, 14, 77, 10) (5, [55, 35, 10], [22, 14, 77]) """ g = a[0] b1 = [g] b2 = [] for x in a[1:]: g1 = gcd(g, x) if g1 == 1: b2.append(x) else: g = g1 b1.append(x) return g, b1, b2

60e95b5f554a84846332938db6af9d10e202ce355b57242be417693634f0038b

from __future__ import print_function, division from sympy.core import Mul from sympy.core.basic import preorder_traversal from sympy.core.function import count_ops from sympy.functions.combinatorial.factorials import binomial, factorial from sympy.functions import gamma from sympy.simplify.gammasimp import gammasimp, _gammasimp from sympy.utilities.timeutils import timethis @timethis('combsimp') def combsimp(expr): r""" Simplify combinatorial expressions. This function takes as input an expression containing factorials, binomials, Pochhammer symbol and other "combinatorial" functions, and tries to minimize the number of those functions and reduce the size of their arguments. The algorithm works by rewriting all combinatorial functions as gamma functions and applying gammasimp() except simplification steps that may make an integer argument non-integer. See docstring of gammasimp for more information. Then it rewrites expression in terms of factorials and binomials by rewriting gammas as factorials and converting (a+b)!/a!b! into binomials. If expression has gamma functions or combinatorial functions with non-integer argument, it is automatically passed to gammasimp. Examples ======== >>> from sympy.simplify import combsimp >>> from sympy import factorial, binomial, symbols >>> n, k = symbols('n k', integer = True) >>> combsimp(factorial(n)/factorial(n - 3)) n*(n - 2)*(n - 1) >>> combsimp(binomial(n+1, k+1)/binomial(n, k)) (n + 1)/(k + 1) """ expr = expr.rewrite(gamma) if any(isinstance(node, gamma) and not node.args[0].is_integer for node in preorder_traversal(expr)): return gammasimp(expr); expr = _gammasimp(expr, as_comb = True) expr = _gamma_as_comb(expr) return expr def _gamma_as_comb(expr): """ Helper function for combsimp. Rewrites expression in terms of factorials and binomials """ expr = expr.rewrite(factorial) from .simplify import bottom_up def f(rv): if not rv.is_Mul: return rv rvd = rv.as_powers_dict() nd_fact_args = [[], []] # numerator, denominator for k in rvd: if isinstance(k, factorial) and rvd[k].is_Integer: if rvd[k].is_positive: nd_fact_args[0].extend([k.args[0]]*rvd[k]) else: nd_fact_args[1].extend([k.args[0]]*-rvd[k]) rvd[k] = 0 if not nd_fact_args[0] or not nd_fact_args[1]: return rv hit = False for m in range(2): i = 0 while i < len(nd_fact_args[m]): ai = nd_fact_args[m][i] for j in range(i + 1, len(nd_fact_args[m])): aj = nd_fact_args[m][j] sum = ai + aj if sum in nd_fact_args[1 - m]: hit = True nd_fact_args[1 - m].remove(sum) del nd_fact_args[m][j] del nd_fact_args[m][i] rvd[binomial(sum, ai if count_ops(ai) < count_ops(aj) else aj)] += ( -1 if m == 0 else 1) break else: i += 1 if hit: return Mul(*([k**rvd[k] for k in rvd] + [factorial(k) for k in nd_fact_args[0]]))/Mul(*[factorial(k) for k in nd_fact_args[1]]) return rv return bottom_up(expr, f)

1e295b989b10a9dd47b15e9a19723ef94edeb77209af1fb5857302392559260e

from __future__ import print_function, division from sympy.core import S, sympify, Mul, Add, Expr from sympy.core.compatibility import range from sympy.core.function import expand_mul, count_ops, _mexpand from sympy.core.symbol import Dummy from sympy.functions import sqrt, sign, root from sympy.polys import Poly, PolynomialError from sympy.utilities import default_sort_key def is_sqrt(expr): """Return True if expr is a sqrt, otherwise False.""" return expr.is_Pow and expr.exp.is_Rational and abs(expr.exp) is S.Half def sqrt_depth(p): """Return the maximum depth of any square root argument of p. >>> from sympy.functions.elementary.miscellaneous import sqrt >>> from sympy.simplify.sqrtdenest import sqrt_depth Neither of these square roots contains any other square roots so the depth is 1: >>> sqrt_depth(1 + sqrt(2)*(1 + sqrt(3))) 1 The sqrt(3) is contained within a square root so the depth is 2: >>> sqrt_depth(1 + sqrt(2)*sqrt(1 + sqrt(3))) 2 """ if p.is_Atom: return 0 elif p.is_Add or p.is_Mul: return max([sqrt_depth(x) for x in p.args], key=default_sort_key) elif is_sqrt(p): return sqrt_depth(p.base) + 1 else: return 0 def is_algebraic(p): """Return True if p is comprised of only Rationals or square roots of Rationals and algebraic operations. Examples ======== >>> from sympy.functions.elementary.miscellaneous import sqrt >>> from sympy.simplify.sqrtdenest import is_algebraic >>> from sympy import cos >>> is_algebraic(sqrt(2)*(3/(sqrt(7) + sqrt(5)*sqrt(2)))) True >>> is_algebraic(sqrt(2)*(3/(sqrt(7) + sqrt(5)*cos(2)))) False """ if p.is_Rational: return True elif p.is_Atom: return False elif is_sqrt(p) or p.is_Pow and p.exp.is_Integer: return is_algebraic(p.base) elif p.is_Add or p.is_Mul: return all(is_algebraic(x) for x in p.args) else: return False def _subsets(n): """ Returns all possible subsets of the set (0, 1, ..., n-1) except the empty set, listed in reversed lexicographical order according to binary representation, so that the case of the fourth root is treated last. Examples ======== >>> from sympy.simplify.sqrtdenest import _subsets >>> _subsets(2) [[1, 0], [0, 1], [1, 1]] """ if n == 1: a = [[1]] elif n == 2: a = [[1, 0], [0, 1], [1, 1]] elif n == 3: a = [[1, 0, 0], [0, 1, 0], [1, 1, 0], [0, 0, 1], [1, 0, 1], [0, 1, 1], [1, 1, 1]] else: b = _subsets(n - 1) a0 = [x + [0] for x in b] a1 = [x + [1] for x in b] a = a0 + [[0]*(n - 1) + [1]] + a1 return a def sqrtdenest(expr, max_iter=3): """Denests sqrts in an expression that contain other square roots if possible, otherwise returns the expr unchanged. This is based on the algorithms of [1]. Examples ======== >>> from sympy.simplify.sqrtdenest import sqrtdenest >>> from sympy import sqrt >>> sqrtdenest(sqrt(5 + 2 * sqrt(6))) sqrt(2) + sqrt(3) See Also ======== sympy.solvers.solvers.unrad References ========== .. [1] http://researcher.watson.ibm.com/researcher/files/us-fagin/symb85.pdf .. [2] D. J. Jeffrey and A. D. Rich, 'Symplifying Square Roots of Square Roots by Denesting' (available at http://www.cybertester.com/data/denest.pdf) """ expr = expand_mul(sympify(expr)) for i in range(max_iter): z = _sqrtdenest0(expr) if expr == z: return expr expr = z return expr def _sqrt_match(p): """Return [a, b, r] for p.match(a + b*sqrt(r)) where, in addition to matching, sqrt(r) also has then maximal sqrt_depth among addends of p. Examples ======== >>> from sympy.functions.elementary.miscellaneous import sqrt >>> from sympy.simplify.sqrtdenest import _sqrt_match >>> _sqrt_match(1 + sqrt(2) + sqrt(2)*sqrt(3) + 2*sqrt(1+sqrt(5))) [1 + sqrt(2) + sqrt(6), 2, 1 + sqrt(5)] """ from sympy.simplify.radsimp import split_surds p = _mexpand(p) if p.is_Number: res = (p, S.Zero, S.Zero) elif p.is_Add: pargs = sorted(p.args, key=default_sort_key) if all((x**2).is_Rational for x in pargs): r, b, a = split_surds(p) res = a, b, r return list(res) # to make the process canonical, the argument is included in the tuple # so when the max is selected, it will be the largest arg having a # given depth v = [(sqrt_depth(x), x, i) for i, x in enumerate(pargs)] nmax = max(v, key=default_sort_key) if nmax[0] == 0: res = [] else: # select r depth, _, i = nmax r = pargs.pop(i) v.pop(i) b = S.One if r.is_Mul: bv = [] rv = [] for x in r.args: if sqrt_depth(x) < depth: bv.append(x) else: rv.append(x) b = Mul._from_args(bv) r = Mul._from_args(rv) # collect terms comtaining r a1 = [] b1 = [b] for x in v: if x[0] < depth: a1.append(x[1]) else: x1 = x[1] if x1 == r: b1.append(1) else: if x1.is_Mul: x1args = list(x1.args) if r in x1args: x1args.remove(r) b1.append(Mul(*x1args)) else: a1.append(x[1]) else: a1.append(x[1]) a = Add(*a1) b = Add(*b1) res = (a, b, r**2) else: b, r = p.as_coeff_Mul() if is_sqrt(r): res = (S.Zero, b, r**2) else: res = [] return list(res) class SqrtdenestStopIteration(StopIteration): pass def _sqrtdenest0(expr): """Returns expr after denesting its arguments.""" if is_sqrt(expr): n, d = expr.as_numer_denom() if d is S.One: # n is a square root if n.base.is_Add: args = sorted(n.base.args, key=default_sort_key) if len(args) > 2 and all((x**2).is_Integer for x in args): try: return _sqrtdenest_rec(n) except SqrtdenestStopIteration: pass expr = sqrt(_mexpand(Add(*[_sqrtdenest0(x) for x in args]))) return _sqrtdenest1(expr) else: n, d = [_sqrtdenest0(i) for i in (n, d)] return n/d if isinstance(expr, Add): cs = [] args = [] for arg in expr.args: c, a = arg.as_coeff_Mul() cs.append(c) args.append(a) if all(c.is_Rational for c in cs) and all(is_sqrt(arg) for arg in args): return _sqrt_ratcomb(cs, args) if isinstance(expr, Expr): args = expr.args if args: return expr.func(*[_sqrtdenest0(a) for a in args]) return expr def _sqrtdenest_rec(expr): """Helper that denests the square root of three or more surds. It returns the denested expression; if it cannot be denested it throws SqrtdenestStopIteration Algorithm: expr.base is in the extension Q_m = Q(sqrt(r_1),..,sqrt(r_k)); split expr.base = a + b*sqrt(r_k), where `a` and `b` are on Q_(m-1) = Q(sqrt(r_1),..,sqrt(r_(k-1))); then a**2 - b**2*r_k is on Q_(m-1); denest sqrt(a**2 - b**2*r_k) and so on. See [1], section 6. Examples ======== >>> from sympy import sqrt >>> from sympy.simplify.sqrtdenest import _sqrtdenest_rec >>> _sqrtdenest_rec(sqrt(-72*sqrt(2) + 158*sqrt(5) + 498)) -sqrt(10) + sqrt(2) + 9 + 9*sqrt(5) >>> w=-6*sqrt(55)-6*sqrt(35)-2*sqrt(22)-2*sqrt(14)+2*sqrt(77)+6*sqrt(10)+65 >>> _sqrtdenest_rec(sqrt(w)) -sqrt(11) - sqrt(7) + sqrt(2) + 3*sqrt(5) """ from sympy.simplify.radsimp import radsimp, rad_rationalize, split_surds if not expr.is_Pow: return sqrtdenest(expr) if expr.base < 0: return sqrt(-1)*_sqrtdenest_rec(sqrt(-expr.base)) g, a, b = split_surds(expr.base) a = a*sqrt(g) if a < b: a, b = b, a c2 = _mexpand(a**2 - b**2) if len(c2.args) > 2: g, a1, b1 = split_surds(c2) a1 = a1*sqrt(g) if a1 < b1: a1, b1 = b1, a1 c2_1 = _mexpand(a1**2 - b1**2) c_1 = _sqrtdenest_rec(sqrt(c2_1)) d_1 = _sqrtdenest_rec(sqrt(a1 + c_1)) num, den = rad_rationalize(b1, d_1) c = _mexpand(d_1/sqrt(2) + num/(den*sqrt(2))) else: c = _sqrtdenest1(sqrt(c2)) if sqrt_depth(c) > 1: raise SqrtdenestStopIteration ac = a + c if len(ac.args) >= len(expr.args): if count_ops(ac) >= count_ops(expr.base): raise SqrtdenestStopIteration d = sqrtdenest(sqrt(ac)) if sqrt_depth(d) > 1: raise SqrtdenestStopIteration num, den = rad_rationalize(b, d) r = d/sqrt(2) + num/(den*sqrt(2)) r = radsimp(r) return _mexpand(r) def _sqrtdenest1(expr, denester=True): """Return denested expr after denesting with simpler methods or, that failing, using the denester.""" from sympy.simplify.simplify import radsimp if not is_sqrt(expr): return expr a = expr.base if a.is_Atom: return expr val = _sqrt_match(a) if not val: return expr a, b, r = val # try a quick numeric denesting d2 = _mexpand(a**2 - b**2*r) if d2.is_Rational: if d2.is_positive: z = _sqrt_numeric_denest(a, b, r, d2) if z is not None: return z else: # fourth root case # sqrtdenest(sqrt(3 + 2*sqrt(3))) = # sqrt(2)*3**(1/4)/2 + sqrt(2)*3**(3/4)/2 dr2 = _mexpand(-d2*r) dr = sqrt(dr2) if dr.is_Rational: z = _sqrt_numeric_denest(_mexpand(b*r), a, r, dr2) if z is not None: return z/root(r, 4) else: z = _sqrt_symbolic_denest(a, b, r) if z is not None: return z if not denester or not is_algebraic(expr): return expr res = sqrt_biquadratic_denest(expr, a, b, r, d2) if res: return res # now call to the denester av0 = [a, b, r, d2] z = _denester([radsimp(expr**2)], av0, 0, sqrt_depth(expr))[0] if av0[1] is None: return expr if z is not None: if sqrt_depth(z) == sqrt_depth(expr) and count_ops(z) > count_ops(expr): return expr return z return expr def _sqrt_symbolic_denest(a, b, r): """Given an expression, sqrt(a + b*sqrt(b)), return the denested expression or None. Algorithm: If r = ra + rb*sqrt(rr), try replacing sqrt(rr) in ``a`` with (y**2 - ra)/rb, and if the result is a quadratic, ca*y**2 + cb*y + cc, and (cb + b)**2 - 4*ca*cc is 0, then sqrt(a + b*sqrt(r)) can be rewritten as sqrt(ca*(sqrt(r) + (cb + b)/(2*ca))**2). Examples ======== >>> from sympy.simplify.sqrtdenest import _sqrt_symbolic_denest, sqrtdenest >>> from sympy import sqrt, Symbol >>> from sympy.abc import x >>> a, b, r = 16 - 2*sqrt(29), 2, -10*sqrt(29) + 55 >>> _sqrt_symbolic_denest(a, b, r) sqrt(-2*sqrt(29) + 11) + sqrt(5) If the expression is numeric, it will be simplified: >>> w = sqrt(sqrt(sqrt(3) + 1) + 1) + 1 + sqrt(2) >>> sqrtdenest(sqrt((w**2).expand())) 1 + sqrt(2) + sqrt(1 + sqrt(1 + sqrt(3))) Otherwise, it will only be simplified if assumptions allow: >>> w = w.subs(sqrt(3), sqrt(x + 3)) >>> sqrtdenest(sqrt((w**2).expand())) sqrt((sqrt(sqrt(sqrt(x + 3) + 1) + 1) + 1 + sqrt(2))**2) Notice that the argument of the sqrt is a square. If x is made positive then the sqrt of the square is resolved: >>> _.subs(x, Symbol('x', positive=True)) sqrt(sqrt(sqrt(x + 3) + 1) + 1) + 1 + sqrt(2) """ a, b, r = map(sympify, (a, b, r)) rval = _sqrt_match(r) if not rval: return None ra, rb, rr = rval if rb: y = Dummy('y', positive=True) try: newa = Poly(a.subs(sqrt(rr), (y**2 - ra)/rb), y) except PolynomialError: return None if newa.degree() == 2: ca, cb, cc = newa.all_coeffs() cb += b if _mexpand(cb**2 - 4*ca*cc).equals(0): z = sqrt(ca*(sqrt(r) + cb/(2*ca))**2) if z.is_number: z = _mexpand(Mul._from_args(z.as_content_primitive())) return z def _sqrt_numeric_denest(a, b, r, d2): """Helper that denest expr = a + b*sqrt(r), with d2 = a**2 - b**2*r > 0 or returns None if not denested. """ from sympy.simplify.simplify import radsimp depthr = sqrt_depth(r) d = sqrt(d2) vad = a + d # sqrt_depth(res) <= sqrt_depth(vad) + 1 # sqrt_depth(expr) = depthr + 2 # there is denesting if sqrt_depth(vad)+1 < depthr + 2 # if vad**2 is Number there is a fourth root if sqrt_depth(vad) < depthr + 1 or (vad**2).is_Rational: vad1 = radsimp(1/vad) return (sqrt(vad/2) + sign(b)*sqrt((b**2*r*vad1/2).expand())).expand() def sqrt_biquadratic_denest(expr, a, b, r, d2): """denest expr = sqrt(a + b*sqrt(r)) where a, b, r are linear combinations of square roots of positive rationals on the rationals (SQRR) and r > 0, b != 0, d2 = a**2 - b**2*r > 0 If it cannot denest it returns None. ALGORITHM Search for a solution A of type SQRR of the biquadratic equation 4*A**4 - 4*a*A**2 + b**2*r = 0 (1) sqd = sqrt(a**2 - b**2*r) Choosing the sqrt to be positive, the possible solutions are A = sqrt(a/2 +/- sqd/2) Since a, b, r are SQRR, then a**2 - b**2*r is a SQRR, so if sqd can be denested, it is done by _sqrtdenest_rec, and the result is a SQRR. Similarly for A. Examples of solutions (in both cases a and sqd are positive): Example of expr with solution sqrt(a/2 + sqd/2) but not solution sqrt(a/2 - sqd/2): expr = sqrt(-sqrt(15) - sqrt(2)*sqrt(-sqrt(5) + 5) - sqrt(3) + 8) a = -sqrt(15) - sqrt(3) + 8; sqd = -2*sqrt(5) - 2 + 4*sqrt(3) Example of expr with solution sqrt(a/2 - sqd/2) but not solution sqrt(a/2 + sqd/2): w = 2 + r2 + r3 + (1 + r3)*sqrt(2 + r2 + 5*r3) expr = sqrt((w**2).expand()) a = 4*sqrt(6) + 8*sqrt(2) + 47 + 28*sqrt(3) sqd = 29 + 20*sqrt(3) Define B = b/2*A; eq.(1) implies a = A**2 + B**2*r; then expr**2 = a + b*sqrt(r) = (A + B*sqrt(r))**2 Examples ======== >>> from sympy import sqrt >>> from sympy.simplify.sqrtdenest import _sqrt_match, sqrt_biquadratic_denest >>> z = sqrt((2*sqrt(2) + 4)*sqrt(2 + sqrt(2)) + 5*sqrt(2) + 8) >>> a, b, r = _sqrt_match(z**2) >>> d2 = a**2 - b**2*r >>> sqrt_biquadratic_denest(z, a, b, r, d2) sqrt(2) + sqrt(sqrt(2) + 2) + 2 """ from sympy.simplify.radsimp import radsimp, rad_rationalize if r <= 0 or d2 < 0 or not b or sqrt_depth(expr.base) < 2: return None for x in (a, b, r): for y in x.args: y2 = y**2 if not y2.is_Integer or not y2.is_positive: return None sqd = _mexpand(sqrtdenest(sqrt(radsimp(d2)))) if sqrt_depth(sqd) > 1: return None x1, x2 = [a/2 + sqd/2, a/2 - sqd/2] # look for a solution A with depth 1 for x in (x1, x2): A = sqrtdenest(sqrt(x)) if sqrt_depth(A) > 1: continue Bn, Bd = rad_rationalize(b, _mexpand(2*A)) B = Bn/Bd z = A + B*sqrt(r) if z < 0: z = -z return _mexpand(z) return None def _denester(nested, av0, h, max_depth_level): """Denests a list of expressions that contain nested square roots. Algorithm based on <http://www.almaden.ibm.com/cs/people/fagin/symb85.pdf>. It is assumed that all of the elements of 'nested' share the same bottom-level radicand. (This is stated in the paper, on page 177, in the paragraph immediately preceding the algorithm.) When evaluating all of the arguments in parallel, the bottom-level radicand only needs to be denested once. This means that calling _denester with x arguments results in a recursive invocation with x+1 arguments; hence _denester has polynomial complexity. However, if the arguments were evaluated separately, each call would result in two recursive invocations, and the algorithm would have exponential complexity. This is discussed in the paper in the middle paragraph of page 179. """ from sympy.simplify.simplify import radsimp if h > max_depth_level: return None, None if av0[1] is None: return None, None if (av0[0] is None and all(n.is_Number for n in nested)): # no arguments are nested for f in _subsets(len(nested)): # test subset 'f' of nested p = _mexpand(Mul(*[nested[i] for i in range(len(f)) if f[i]])) if f.count(1) > 1 and f[-1]: p = -p sqp = sqrt(p) if sqp.is_Rational: return sqp, f # got a perfect square so return its square root. # Otherwise, return the radicand from the previous invocation. return sqrt(nested[-1]), [0]*len(nested) else: R = None if av0[0] is not None: values = [av0[:2]] R = av0[2] nested2 = [av0[3], R] av0[0] = None else: values = list(filter(None, [_sqrt_match(expr) for expr in nested])) for v in values: if v[2]: # Since if b=0, r is not defined if R is not None: if R != v[2]: av0[1] = None return None, None else: R = v[2] if R is None: # return the radicand from the previous invocation return sqrt(nested[-1]), [0]*len(nested) nested2 = [_mexpand(v[0]**2) - _mexpand(R*v[1]**2) for v in values] + [R] d, f = _denester(nested2, av0, h + 1, max_depth_level) if not f: return None, None if not any(f[i] for i in range(len(nested))): v = values[-1] return sqrt(v[0] + _mexpand(v[1]*d)), f else: p = Mul(*[nested[i] for i in range(len(nested)) if f[i]]) v = _sqrt_match(p) if 1 in f and f.index(1) < len(nested) - 1 and f[len(nested) - 1]: v[0] = -v[0] v[1] = -v[1] if not f[len(nested)]: # Solution denests with square roots vad = _mexpand(v[0] + d) if vad <= 0: # return the radicand from the previous invocation. return sqrt(nested[-1]), [0]*len(nested) if not(sqrt_depth(vad) <= sqrt_depth(R) + 1 or (vad**2).is_Number): av0[1] = None return None, None sqvad = _sqrtdenest1(sqrt(vad), denester=False) if not (sqrt_depth(sqvad) <= sqrt_depth(R) + 1): av0[1] = None return None, None sqvad1 = radsimp(1/sqvad) res = _mexpand(sqvad/sqrt(2) + (v[1]*sqrt(R)*sqvad1/sqrt(2))) return res, f # sign(v[1])*sqrt(_mexpand(v[1]**2*R*vad1/2))), f else: # Solution requires a fourth root s2 = _mexpand(v[1]*R) + d if s2 <= 0: return sqrt(nested[-1]), [0]*len(nested) FR, s = root(_mexpand(R), 4), sqrt(s2) return _mexpand(s/(sqrt(2)*FR) + v[0]*FR/(sqrt(2)*s)), f def _sqrt_ratcomb(cs, args): """Denest rational combinations of radicals. Based on section 5 of [1]. Examples ======== >>> from sympy import sqrt >>> from sympy.simplify.sqrtdenest import sqrtdenest >>> z = sqrt(1+sqrt(3)) + sqrt(3+3*sqrt(3)) - sqrt(10+6*sqrt(3)) >>> sqrtdenest(z) 0 """ from sympy.simplify.radsimp import radsimp # check if there exists a pair of sqrt that can be denested def find(a): n = len(a) for i in range(n - 1): for j in range(i + 1, n): s1 = a[i].base s2 = a[j].base p = _mexpand(s1 * s2) s = sqrtdenest(sqrt(p)) if s != sqrt(p): return s, i, j indices = find(args) if indices is None: return Add(*[c * arg for c, arg in zip(cs, args)]) s, i1, i2 = indices c2 = cs.pop(i2) args.pop(i2) a1 = args[i1] # replace a2 by s/a1 cs[i1] += radsimp(c2 * s / a1.base) return _sqrt_ratcomb(cs, args)

56d18a397c43380f2c040fbd767e49a2b7f533fc690579c7cb1e34b225e64f8e

from __future__ import print_function, division from sympy.core import Function, S, Mul, Pow, Add from sympy.core.compatibility import ordered, default_sort_key from sympy.core.function import count_ops, expand_func from sympy.functions.combinatorial.factorials import binomial from sympy.functions import gamma, sqrt, sin from sympy.polys import factor, cancel from sympy.utilities.iterables import sift, uniq def gammasimp(expr): r""" Simplify expressions with gamma functions. This function takes as input an expression containing gamma functions or functions that can be rewritten in terms of gamma functions and tries to minimize the number of those functions and reduce the size of their arguments. The algorithm works by rewriting all gamma functions as expressions involving rising factorials (Pochhammer symbols) and applies recurrence relations and other transformations applicable to rising factorials, to reduce their arguments, possibly letting the resulting rising factorial to cancel. Rising factorials with the second argument being an integer are expanded into polynomial forms and finally all other rising factorial are rewritten in terms of gamma functions. Then the following two steps are performed. 1. Reduce the number of gammas by applying the reflection theorem gamma(x)*gamma(1-x) == pi/sin(pi*x). 2. Reduce the number of gammas by applying the multiplication theorem gamma(x)*gamma(x+1/n)*...*gamma(x+(n-1)/n) == C*gamma(n*x). It then reduces the number of prefactors by absorbing them into gammas where possible and expands gammas with rational argument. All transformation rules can be found (or was derived from) here: 1. http://functions.wolfram.com/GammaBetaErf/Pochhammer/17/01/02/ 2. http://functions.wolfram.com/GammaBetaErf/Pochhammer/27/01/0005/ Examples ======== >>> from sympy.simplify import gammasimp >>> from sympy import gamma, factorial, Symbol >>> from sympy.abc import x >>> n = Symbol('n', integer = True) >>> gammasimp(gamma(x)/gamma(x - 3)) (x - 3)*(x - 2)*(x - 1) >>> gammasimp(gamma(n + 3)) gamma(n + 3) """ expr = expr.rewrite(gamma) return _gammasimp(expr, as_comb = False) def _gammasimp(expr, as_comb): """ Helper function for gammasimp and combsimp. Simplifies expressions written in terms of gamma function. If as_comb is True, it tries to preserve integer arguments. See docstring of gammasimp for more information. This was part of combsimp() in combsimp.py. """ expr = expr.replace(gamma, lambda n: _rf(1, (n - 1).expand())) if as_comb: expr = expr.replace(_rf, lambda a, b: gamma(b + 1)) else: expr = expr.replace(_rf, lambda a, b: gamma(a + b)/gamma(a)) def rule(n, k): coeff, rewrite = S.One, False cn, _n = n.as_coeff_Add() if _n and cn.is_Integer and cn: coeff *= _rf(_n + 1, cn)/_rf(_n - k + 1, cn) rewrite = True n = _n # this sort of binomial has already been removed by # rising factorials but is left here in case the order # of rule application is changed if k.is_Add: ck, _k = k.as_coeff_Add() if _k and ck.is_Integer and ck: coeff *= _rf(n - ck - _k + 1, ck)/_rf(_k + 1, ck) rewrite = True k = _k if count_ops(k) > count_ops(n - k): rewrite = True k = n - k if rewrite: return coeff*binomial(n, k) expr = expr.replace(binomial, rule) def rule_gamma(expr, level=0): """ Simplify products of gamma functions further. """ if expr.is_Atom: return expr def gamma_rat(x): # helper to simplify ratios of gammas was = x.count(gamma) xx = x.replace(gamma, lambda n: _rf(1, (n - 1).expand() ).replace(_rf, lambda a, b: gamma(a + b)/gamma(a))) if xx.count(gamma) < was: x = xx return x def gamma_factor(x): # return True if there is a gamma factor in shallow args if isinstance(x, gamma): return True if x.is_Add or x.is_Mul: return any(gamma_factor(xi) for xi in x.args) if x.is_Pow and (x.exp.is_integer or x.base.is_positive): return gamma_factor(x.base) return False # recursion step if level == 0: expr = expr.func(*[rule_gamma(x, level + 1) for x in expr.args]) level += 1 if not expr.is_Mul: return expr # non-commutative step if level == 1: args, nc = expr.args_cnc() if not args: return expr if nc: return rule_gamma(Mul._from_args(args), level + 1)*Mul._from_args(nc) level += 1 # pure gamma handling, not factor absorption if level == 2: T, F = sift(expr.args, gamma_factor, binary=True) gamma_ind = Mul(*F) d = Mul(*T) nd, dd = d.as_numer_denom() for ipass in range(2): args = list(ordered(Mul.make_args(nd))) for i, ni in enumerate(args): if ni.is_Add: ni, dd = Add(*[ rule_gamma(gamma_rat(a/dd), level + 1) for a in ni.args] ).as_numer_denom() args[i] = ni if not dd.has(gamma): break nd = Mul(*args) if ipass == 0 and not gamma_factor(nd): break nd, dd = dd, nd # now process in reversed order expr = gamma_ind*nd/dd if not (expr.is_Mul and (gamma_factor(dd) or gamma_factor(nd))): return expr level += 1 # iteration until constant if level == 3: while True: was = expr expr = rule_gamma(expr, 4) if expr == was: return expr numer_gammas = [] denom_gammas = [] numer_others = [] denom_others = [] def explicate(p): if p is S.One: return None, [] b, e = p.as_base_exp() if e.is_Integer: if isinstance(b, gamma): return True, [b.args[0]]*e else: return False, [b]*e else: return False, [p] newargs = list(ordered(expr.args)) while newargs: n, d = newargs.pop().as_numer_denom() isg, l = explicate(n) if isg: numer_gammas.extend(l) elif isg is False: numer_others.extend(l) isg, l = explicate(d) if isg: denom_gammas.extend(l) elif isg is False: denom_others.extend(l) # =========== level 2 work: pure gamma manipulation ========= if not as_comb: # Try to reduce the number of gamma factors by applying the # reflection formula gamma(x)*gamma(1-x) = pi/sin(pi*x) for gammas, numer, denom in [( numer_gammas, numer_others, denom_others), (denom_gammas, denom_others, numer_others)]: new = [] while gammas: g1 = gammas.pop() if g1.is_integer: new.append(g1) continue for i, g2 in enumerate(gammas): n = g1 + g2 - 1 if not n.is_Integer: continue numer.append(S.Pi) denom.append(sin(S.Pi*g1)) gammas.pop(i) if n > 0: for k in range(n): numer.append(1 - g1 + k) elif n < 0: for k in range(-n): denom.append(-g1 - k) break else: new.append(g1) # /!\ updating IN PLACE gammas[:] = new # Try to reduce the number of gammas by using the duplication # theorem to cancel an upper and lower: gamma(2*s)/gamma(s) = # 2**(2*s + 1)/(4*sqrt(pi))*gamma(s + 1/2). Although this could # be done with higher argument ratios like gamma(3*x)/gamma(x), # this would not reduce the number of gammas as in this case. for ng, dg, no, do in [(numer_gammas, denom_gammas, numer_others, denom_others), (denom_gammas, numer_gammas, denom_others, numer_others)]: while True: for x in ng: for y in dg: n = x - 2*y if n.is_Integer: break else: continue break else: break ng.remove(x) dg.remove(y) if n > 0: for k in range(n): no.append(2*y + k) elif n < 0: for k in range(-n): do.append(2*y - 1 - k) ng.append(y + S(1)/2) no.append(2**(2*y - 1)) do.append(sqrt(S.Pi)) # Try to reduce the number of gamma factors by applying the # multiplication theorem (used when n gammas with args differing # by 1/n mod 1 are encountered). # # run of 2 with args differing by 1/2 # # >>> gammasimp(gamma(x)*gamma(x+S.Half)) # 2*sqrt(2)*2**(-2*x - 1/2)*sqrt(pi)*gamma(2*x) # # run of 3 args differing by 1/3 (mod 1) # # >>> gammasimp(gamma(x)*gamma(x+S(1)/3)*gamma(x+S(2)/3)) # 6*3**(-3*x - 1/2)*pi*gamma(3*x) # >>> gammasimp(gamma(x)*gamma(x+S(1)/3)*gamma(x+S(5)/3)) # 2*3**(-3*x - 1/2)*pi*(3*x + 2)*gamma(3*x) # def _run(coeffs): # find runs in coeffs such that the difference in terms (mod 1) # of t1, t2, ..., tn is 1/n u = list(uniq(coeffs)) for i in range(len(u)): dj = ([((u[j] - u[i]) % 1, j) for j in range(i + 1, len(u))]) for one, j in dj: if one.p == 1 and one.q != 1: n = one.q got = [i] get = list(range(1, n)) for d, j in dj: m = n*d if m.is_Integer and m in get: get.remove(m) got.append(j) if not get: break else: continue for i, j in enumerate(got): c = u[j] coeffs.remove(c) got[i] = c return one.q, got[0], got[1:] def _mult_thm(gammas, numer, denom): # pull off and analyze the leading coefficient from each gamma arg # looking for runs in those Rationals # expr -> coeff + resid -> rats[resid] = coeff rats = {} for g in gammas: c, resid = g.as_coeff_Add() rats.setdefault(resid, []).append(c) # look for runs in Rationals for each resid keys = sorted(rats, key=default_sort_key) for resid in keys: coeffs = list(sorted(rats[resid])) new = [] while True: run = _run(coeffs) if run is None: break # process the sequence that was found: # 1) convert all the gamma functions to have the right # argument (could be off by an integer) # 2) append the factors corresponding to the theorem # 3) append the new gamma function n, ui, other = run # (1) for u in other: con = resid + u - 1 for k in range(int(u - ui)): numer.append(con - k) con = n*(resid + ui) # for (2) and (3) # (2) numer.append((2*S.Pi)**(S(n - 1)/2)* n**(S(1)/2 - con)) # (3) new.append(con) # restore resid to coeffs rats[resid] = [resid + c for c in coeffs] + new # rebuild the gamma arguments g = [] for resid in keys: g += rats[resid] # /!\ updating IN PLACE gammas[:] = g for l, numer, denom in [(numer_gammas, numer_others, denom_others), (denom_gammas, denom_others, numer_others)]: _mult_thm(l, numer, denom) # =========== level >= 2 work: factor absorption ========= if level >= 2: # Try to absorb factors into the gammas: x*gamma(x) -> gamma(x + 1) # and gamma(x)/(x - 1) -> gamma(x - 1) # This code (in particular repeated calls to find_fuzzy) can be very # slow. def find_fuzzy(l, x): if not l: return S1, T1 = compute_ST(x) for y in l: S2, T2 = inv[y] if T1 != T2 or (not S1.intersection(S2) and (S1 != set() or S2 != set())): continue # XXX we want some simplification (e.g. cancel or # simplify) but no matter what it's slow. a = len(cancel(x/y).free_symbols) b = len(x.free_symbols) c = len(y.free_symbols) # TODO is there a better heuristic? if a == 0 and (b > 0 or c > 0): return y # We thus try to avoid expensive calls by building the following # "invariants": For every factor or gamma function argument # - the set of free symbols S # - the set of functional components T # We will only try to absorb if T1==T2 and (S1 intersect S2 != emptyset # or S1 == S2 == emptyset) inv = {} def compute_ST(expr): if expr in inv: return inv[expr] return (expr.free_symbols, expr.atoms(Function).union( set(e.exp for e in expr.atoms(Pow)))) def update_ST(expr): inv[expr] = compute_ST(expr) for expr in numer_gammas + denom_gammas + numer_others + denom_others: update_ST(expr) for gammas, numer, denom in [( numer_gammas, numer_others, denom_others), (denom_gammas, denom_others, numer_others)]: new = [] while gammas: g = gammas.pop() cont = True while cont: cont = False y = find_fuzzy(numer, g) if y is not None: numer.remove(y) if y != g: numer.append(y/g) update_ST(y/g) g += 1 cont = True y = find_fuzzy(denom, g - 1) if y is not None: denom.remove(y) if y != g - 1: numer.append((g - 1)/y) update_ST((g - 1)/y) g -= 1 cont = True new.append(g) # /!\ updating IN PLACE gammas[:] = new # =========== rebuild expr ================================== return Mul(*[gamma(g) for g in numer_gammas]) \ / Mul(*[gamma(g) for g in denom_gammas]) \ * Mul(*numer_others) / Mul(*denom_others) # (for some reason we cannot use Basic.replace in this case) was = factor(expr) expr = rule_gamma(was) if expr != was: expr = factor(expr) expr = expr.replace(gamma, lambda n: expand_func(gamma(n)) if n.is_Rational else gamma(n)) return expr class _rf(Function): @classmethod def eval(cls, a, b): if b.is_Integer: if not b: return S.One n, result = int(b), S.One if n > 0: for i in range(n): result *= a + i return result elif n < 0: for i in range(1, -n + 1): result *= a - i return 1/result else: if b.is_Add: c, _b = b.as_coeff_Add() if c.is_Integer: if c > 0: return _rf(a, _b)*_rf(a + _b, c) elif c < 0: return _rf(a, _b)/_rf(a + _b + c, -c) if a.is_Add: c, _a = a.as_coeff_Add() if c.is_Integer: if c > 0: return _rf(_a, b)*_rf(_a + b, c)/_rf(_a, c) elif c < 0: return _rf(_a, b)*_rf(_a + c, -c)/_rf(_a + b + c, -c)

915f0c36208115b19dd4e2d7f4ef7046fbb64ce4bf9588c6d6fa22ce838fa03f

from __future__ import print_function, division from collections import defaultdict from sympy.core import (sympify, Basic, S, Expr, expand_mul, factor_terms, Mul, Dummy, igcd, FunctionClass, Add, symbols, Wild, expand) from sympy.core.cache import cacheit from sympy.core.compatibility import reduce, iterable, SYMPY_INTS from sympy.core.function import count_ops, _mexpand from sympy.core.numbers import I, Integer from sympy.functions import sin, cos, exp, cosh, tanh, sinh, tan, cot, coth from sympy.functions.elementary.hyperbolic import HyperbolicFunction from sympy.functions.elementary.trigonometric import TrigonometricFunction from sympy.polys import Poly, factor, cancel, parallel_poly_from_expr from sympy.polys.domains import ZZ from sympy.polys.polyerrors import PolificationFailed from sympy.polys.polytools import groebner from sympy.simplify.cse_main import cse from sympy.strategies.core import identity from sympy.strategies.tree import greedy from sympy.utilities.misc import debug def trigsimp_groebner(expr, hints=[], quick=False, order="grlex", polynomial=False): """ Simplify trigonometric expressions using a groebner basis algorithm. This routine takes a fraction involving trigonometric or hyperbolic expressions, and tries to simplify it. The primary metric is the total degree. Some attempts are made to choose the simplest possible expression of the minimal degree, but this is non-rigorous, and also very slow (see the ``quick=True`` option). If ``polynomial`` is set to True, instead of simplifying numerator and denominator together, this function just brings numerator and denominator into a canonical form. This is much faster, but has potentially worse results. However, if the input is a polynomial, then the result is guaranteed to be an equivalent polynomial of minimal degree. The most important option is hints. Its entries can be any of the following: - a natural number - a function - an iterable of the form (func, var1, var2, ...) - anything else, interpreted as a generator A number is used to indicate that the search space should be increased. A function is used to indicate that said function is likely to occur in a simplified expression. An iterable is used indicate that func(var1 + var2 + ...) is likely to occur in a simplified . An additional generator also indicates that it is likely to occur. (See examples below). This routine carries out various computationally intensive algorithms. The option ``quick=True`` can be used to suppress one particularly slow step (at the expense of potentially more complicated results, but never at the expense of increased total degree). Examples ======== >>> from sympy.abc import x, y >>> from sympy import sin, tan, cos, sinh, cosh, tanh >>> from sympy.simplify.trigsimp import trigsimp_groebner Suppose you want to simplify ``sin(x)*cos(x)``. Naively, nothing happens: >>> ex = sin(x)*cos(x) >>> trigsimp_groebner(ex) sin(x)*cos(x) This is because ``trigsimp_groebner`` only looks for a simplification involving just ``sin(x)`` and ``cos(x)``. You can tell it to also try ``2*x`` by passing ``hints=[2]``: >>> trigsimp_groebner(ex, hints=[2]) sin(2*x)/2 >>> trigsimp_groebner(sin(x)**2 - cos(x)**2, hints=[2]) -cos(2*x) Increasing the search space this way can quickly become expensive. A much faster way is to give a specific expression that is likely to occur: >>> trigsimp_groebner(ex, hints=[sin(2*x)]) sin(2*x)/2 Hyperbolic expressions are similarly supported: >>> trigsimp_groebner(sinh(2*x)/sinh(x)) 2*cosh(x) Note how no hints had to be passed, since the expression already involved ``2*x``. The tangent function is also supported. You can either pass ``tan`` in the hints, to indicate that tan should be tried whenever cosine or sine are, or you can pass a specific generator: >>> trigsimp_groebner(sin(x)/cos(x), hints=[tan]) tan(x) >>> trigsimp_groebner(sinh(x)/cosh(x), hints=[tanh(x)]) tanh(x) Finally, you can use the iterable form to suggest that angle sum formulae should be tried: >>> ex = (tan(x) + tan(y))/(1 - tan(x)*tan(y)) >>> trigsimp_groebner(ex, hints=[(tan, x, y)]) tan(x + y) """ # TODO # - preprocess by replacing everything by funcs we can handle # - optionally use cot instead of tan # - more intelligent hinting. # For example, if the ideal is small, and we have sin(x), sin(y), # add sin(x + y) automatically... ? # - algebraic numbers ... # - expressions of lowest degree are not distinguished properly # e.g. 1 - sin(x)**2 # - we could try to order the generators intelligently, so as to influence # which monomials appear in the quotient basis # THEORY # ------ # Ratsimpmodprime above can be used to "simplify" a rational function # modulo a prime ideal. "Simplify" mainly means finding an equivalent # expression of lower total degree. # # We intend to use this to simplify trigonometric functions. To do that, # we need to decide (a) which ring to use, and (b) modulo which ideal to # simplify. In practice, (a) means settling on a list of "generators" # a, b, c, ..., such that the fraction we want to simplify is a rational # function in a, b, c, ..., with coefficients in ZZ (integers). # (2) means that we have to decide what relations to impose on the # generators. There are two practical problems: # (1) The ideal has to be *prime* (a technical term). # (2) The relations have to be polynomials in the generators. # # We typically have two kinds of generators: # - trigonometric expressions, like sin(x), cos(5*x), etc # - "everything else", like gamma(x), pi, etc. # # Since this function is trigsimp, we will concentrate on what to do with # trigonometric expressions. We can also simplify hyperbolic expressions, # but the extensions should be clear. # # One crucial point is that all *other* generators really should behave # like indeterminates. In particular if (say) "I" is one of them, then # in fact I**2 + 1 = 0 and we may and will compute non-sensical # expressions. However, we can work with a dummy and add the relation # I**2 + 1 = 0 to our ideal, then substitute back in the end. # # Now regarding trigonometric generators. We split them into groups, # according to the argument of the trigonometric functions. We want to # organise this in such a way that most trigonometric identities apply in # the same group. For example, given sin(x), cos(2*x) and cos(y), we would # group as [sin(x), cos(2*x)] and [cos(y)]. # # Our prime ideal will be built in three steps: # (1) For each group, compute a "geometrically prime" ideal of relations. # Geometrically prime means that it generates a prime ideal in # CC[gens], not just ZZ[gens]. # (2) Take the union of all the generators of the ideals for all groups. # By the geometric primality condition, this is still prime. # (3) Add further inter-group relations which preserve primality. # # Step (1) works as follows. We will isolate common factors in the # argument, so that all our generators are of the form sin(n*x), cos(n*x) # or tan(n*x), with n an integer. Suppose first there are no tan terms. # The ideal [sin(x)**2 + cos(x)**2 - 1] is geometrically prime, since # X**2 + Y**2 - 1 is irreducible over CC. # Now, if we have a generator sin(n*x), than we can, using trig identities, # express sin(n*x) as a polynomial in sin(x) and cos(x). We can add this # relation to the ideal, preserving geometric primality, since the quotient # ring is unchanged. # Thus we have treated all sin and cos terms. # For tan(n*x), we add a relation tan(n*x)*cos(n*x) - sin(n*x) = 0. # (This requires of course that we already have relations for cos(n*x) and # sin(n*x).) It is not obvious, but it seems that this preserves geometric # primality. # XXX A real proof would be nice. HELP! # Sketch that <S**2 + C**2 - 1, C*T - S> is a prime ideal of # CC[S, C, T]: # - it suffices to show that the projective closure in CP**3 is # irreducible # - using the half-angle substitutions, we can express sin(x), tan(x), # cos(x) as rational functions in tan(x/2) # - from this, we get a rational map from CP**1 to our curve # - this is a morphism, hence the curve is prime # # Step (2) is trivial. # # Step (3) works by adding selected relations of the form # sin(x + y) - sin(x)*cos(y) - sin(y)*cos(x), etc. Geometric primality is # preserved by the same argument as before. def parse_hints(hints): """Split hints into (n, funcs, iterables, gens).""" n = 1 funcs, iterables, gens = [], [], [] for e in hints: if isinstance(e, (SYMPY_INTS, Integer)): n = e elif isinstance(e, FunctionClass): funcs.append(e) elif iterable(e): iterables.append((e[0], e[1:])) # XXX sin(x+2y)? # Note: we go through polys so e.g. # sin(-x) -> -sin(x) -> sin(x) gens.extend(parallel_poly_from_expr( [e[0](x) for x in e[1:]] + [e[0](Add(*e[1:]))])[1].gens) else: gens.append(e) return n, funcs, iterables, gens def build_ideal(x, terms): """ Build generators for our ideal. Terms is an iterable with elements of the form (fn, coeff), indicating that we have a generator fn(coeff*x). If any of the terms is trigonometric, sin(x) and cos(x) are guaranteed to appear in terms. Similarly for hyperbolic functions. For tan(n*x), sin(n*x) and cos(n*x) are guaranteed. """ I = [] y = Dummy('y') for fn, coeff in terms: for c, s, t, rel in ( [cos, sin, tan, cos(x)**2 + sin(x)**2 - 1], [cosh, sinh, tanh, cosh(x)**2 - sinh(x)**2 - 1]): if coeff == 1 and fn in [c, s]: I.append(rel) elif fn == t: I.append(t(coeff*x)*c(coeff*x) - s(coeff*x)) elif fn in [c, s]: cn = fn(coeff*y).expand(trig=True).subs(y, x) I.append(fn(coeff*x) - cn) return list(set(I)) def analyse_gens(gens, hints): """ Analyse the generators ``gens``, using the hints ``hints``. The meaning of ``hints`` is described in the main docstring. Return a new list of generators, and also the ideal we should work with. """ # First parse the hints n, funcs, iterables, extragens = parse_hints(hints) debug('n=%s' % n, 'funcs:', funcs, 'iterables:', iterables, 'extragens:', extragens) # We just add the extragens to gens and analyse them as before gens = list(gens) gens.extend(extragens) # remove duplicates funcs = list(set(funcs)) iterables = list(set(iterables)) gens = list(set(gens)) # all the functions we can do anything with allfuncs = {sin, cos, tan, sinh, cosh, tanh} # sin(3*x) -> ((3, x), sin) trigterms = [(g.args[0].as_coeff_mul(), g.func) for g in gens if g.func in allfuncs] # Our list of new generators - start with anything that we cannot # work with (i.e. is not a trigonometric term) freegens = [g for g in gens if g.func not in allfuncs] newgens = [] trigdict = {} for (coeff, var), fn in trigterms: trigdict.setdefault(var, []).append((coeff, fn)) res = [] # the ideal for key, val in trigdict.items(): # We have now assembeled a dictionary. Its keys are common # arguments in trigonometric expressions, and values are lists of # pairs (fn, coeff). x0, (fn, coeff) in trigdict means that we # need to deal with fn(coeff*x0). We take the rational gcd of the # coeffs, call it ``gcd``. We then use x = x0/gcd as "base symbol", # all other arguments are integral multiples thereof. # We will build an ideal which works with sin(x), cos(x). # If hint tan is provided, also work with tan(x). Moreover, if # n > 1, also work with sin(k*x) for k <= n, and similarly for cos # (and tan if the hint is provided). Finally, any generators which # the ideal does not work with but we need to accommodate (either # because it was in expr or because it was provided as a hint) # we also build into the ideal. # This selection process is expressed in the list ``terms``. # build_ideal then generates the actual relations in our ideal, # from this list. fns = [x[1] for x in val] val = [x[0] for x in val] gcd = reduce(igcd, val) terms = [(fn, v/gcd) for (fn, v) in zip(fns, val)] fs = set(funcs + fns) for c, s, t in ([cos, sin, tan], [cosh, sinh, tanh]): if any(x in fs for x in (c, s, t)): fs.add(c) fs.add(s) for fn in fs: for k in range(1, n + 1): terms.append((fn, k)) extra = [] for fn, v in terms: if fn == tan: extra.append((sin, v)) extra.append((cos, v)) if fn in [sin, cos] and tan in fs: extra.append((tan, v)) if fn == tanh: extra.append((sinh, v)) extra.append((cosh, v)) if fn in [sinh, cosh] and tanh in fs: extra.append((tanh, v)) terms.extend(extra) x = gcd*Mul(*key) r = build_ideal(x, terms) res.extend(r) newgens.extend(set(fn(v*x) for fn, v in terms)) # Add generators for compound expressions from iterables for fn, args in iterables: if fn == tan: # Tan expressions are recovered from sin and cos. iterables.extend([(sin, args), (cos, args)]) elif fn == tanh: # Tanh expressions are recovered from sihn and cosh. iterables.extend([(sinh, args), (cosh, args)]) else: dummys = symbols('d:%i' % len(args), cls=Dummy) expr = fn( Add(*dummys)).expand(trig=True).subs(list(zip(dummys, args))) res.append(fn(Add(*args)) - expr) if myI in gens: res.append(myI**2 + 1) freegens.remove(myI) newgens.append(myI) return res, freegens, newgens myI = Dummy('I') expr = expr.subs(S.ImaginaryUnit, myI) subs = [(myI, S.ImaginaryUnit)] num, denom = cancel(expr).as_numer_denom() try: (pnum, pdenom), opt = parallel_poly_from_expr([num, denom]) except PolificationFailed: return expr debug('initial gens:', opt.gens) ideal, freegens, gens = analyse_gens(opt.gens, hints) debug('ideal:', ideal) debug('new gens:', gens, " -- len", len(gens)) debug('free gens:', freegens, " -- len", len(gens)) # NOTE we force the domain to be ZZ to stop polys from injecting generators # (which is usually a sign of a bug in the way we build the ideal) if not gens: return expr G = groebner(ideal, order=order, gens=gens, domain=ZZ) debug('groebner basis:', list(G), " -- len", len(G)) # If our fraction is a polynomial in the free generators, simplify all # coefficients separately: from sympy.simplify.ratsimp import ratsimpmodprime if freegens and pdenom.has_only_gens(*set(gens).intersection(pdenom.gens)): num = Poly(num, gens=gens+freegens).eject(*gens) res = [] for monom, coeff in num.terms(): ourgens = set(parallel_poly_from_expr([coeff, denom])[1].gens) # We compute the transitive closure of all generators that can # be reached from our generators through relations in the ideal. changed = True while changed: changed = False for p in ideal: p = Poly(p) if not ourgens.issuperset(p.gens) and \ not p.has_only_gens(*set(p.gens).difference(ourgens)): changed = True ourgens.update(p.exclude().gens) # NOTE preserve order! realgens = [x for x in gens if x in ourgens] # The generators of the ideal have now been (implicitly) split # into two groups: those involving ourgens and those that don't. # Since we took the transitive closure above, these two groups # live in subgrings generated by a *disjoint* set of variables. # Any sensible groebner basis algorithm will preserve this disjoint # structure (i.e. the elements of the groebner basis can be split # similarly), and and the two subsets of the groebner basis then # form groebner bases by themselves. (For the smaller generating # sets, of course.) ourG = [g.as_expr() for g in G.polys if g.has_only_gens(*ourgens.intersection(g.gens))] res.append(Mul(*[a**b for a, b in zip(freegens, monom)]) * \ ratsimpmodprime(coeff/denom, ourG, order=order, gens=realgens, quick=quick, domain=ZZ, polynomial=polynomial).subs(subs)) return Add(*res) # NOTE The following is simpler and has less assumptions on the # groebner basis algorithm. If the above turns out to be broken, # use this. return Add(*[Mul(*[a**b for a, b in zip(freegens, monom)]) * \ ratsimpmodprime(coeff/denom, list(G), order=order, gens=gens, quick=quick, domain=ZZ) for monom, coeff in num.terms()]) else: return ratsimpmodprime( expr, list(G), order=order, gens=freegens+gens, quick=quick, domain=ZZ, polynomial=polynomial).subs(subs) _trigs = (TrigonometricFunction, HyperbolicFunction) def trigsimp(expr, **opts): """ reduces expression by using known trig identities Notes ===== method: - Determine the method to use. Valid choices are 'matching' (default), 'groebner', 'combined', and 'fu'. If 'matching', simplify the expression recursively by targeting common patterns. If 'groebner', apply an experimental groebner basis algorithm. In this case further options are forwarded to ``trigsimp_groebner``, please refer to its docstring. If 'combined', first run the groebner basis algorithm with small default parameters, then run the 'matching' algorithm. 'fu' runs the collection of trigonometric transformations described by Fu, et al. (see the `fu` docstring). Examples ======== >>> from sympy import trigsimp, sin, cos, log >>> from sympy.abc import x, y >>> e = 2*sin(x)**2 + 2*cos(x)**2 >>> trigsimp(e) 2 Simplification occurs wherever trigonometric functions are located. >>> trigsimp(log(e)) log(2) Using `method="groebner"` (or `"combined"`) might lead to greater simplification. The old trigsimp routine can be accessed as with method 'old'. >>> from sympy import coth, tanh >>> t = 3*tanh(x)**7 - 2/coth(x)**7 >>> trigsimp(t, method='old') == t True >>> trigsimp(t) tanh(x)**7 """ from sympy.simplify.fu import fu expr = sympify(expr) try: return expr._eval_trigsimp(**opts) except AttributeError: pass old = opts.pop('old', False) if not old: opts.pop('deep', None) opts.pop('recursive', None) method = opts.pop('method', 'matching') else: method = 'old' def groebnersimp(ex, **opts): def traverse(e): if e.is_Atom: return e args = [traverse(x) for x in e.args] if e.is_Function or e.is_Pow: args = [trigsimp_groebner(x, **opts) for x in args] return e.func(*args) new = traverse(ex) if not isinstance(new, Expr): return new return trigsimp_groebner(new, **opts) trigsimpfunc = { 'fu': (lambda x: fu(x, **opts)), 'matching': (lambda x: futrig(x)), 'groebner': (lambda x: groebnersimp(x, **opts)), 'combined': (lambda x: futrig(groebnersimp(x, polynomial=True, hints=[2, tan]))), 'old': lambda x: trigsimp_old(x, **opts), }[method] return trigsimpfunc(expr) def exptrigsimp(expr): """ Simplifies exponential / trigonometric / hyperbolic functions. Examples ======== >>> from sympy import exptrigsimp, exp, cosh, sinh >>> from sympy.abc import z >>> exptrigsimp(exp(z) + exp(-z)) 2*cosh(z) >>> exptrigsimp(cosh(z) - sinh(z)) exp(-z) """ from sympy.simplify.fu import hyper_as_trig, TR2i from sympy.simplify.simplify import bottom_up def exp_trig(e): # select the better of e, and e rewritten in terms of exp or trig # functions choices = [e] if e.has(*_trigs): choices.append(e.rewrite(exp)) choices.append(e.rewrite(cos)) return min(*choices, key=count_ops) newexpr = bottom_up(expr, exp_trig) def f(rv): if not rv.is_Mul: return rv commutative_part, noncommutative_part = rv.args_cnc() # Since as_powers_dict loses order information, # if there is more than one noncommutative factor, # it should only be used to simplify the commutative part. if (len(noncommutative_part) > 1): return f(Mul(*commutative_part))*Mul(*noncommutative_part) rvd = rv.as_powers_dict() newd = rvd.copy() def signlog(expr, sign=1): if expr is S.Exp1: return sign, 1 elif isinstance(expr, exp): return sign, expr.args[0] elif sign == 1: return signlog(-expr, sign=-1) else: return None, None ee = rvd[S.Exp1] for k in rvd: if k.is_Add and len(k.args) == 2: # k == c*(1 + sign*E**x) c = k.args[0] sign, x = signlog(k.args[1]/c) if not x: continue m = rvd[k] newd[k] -= m if ee == -x*m/2: # sinh and cosh newd[S.Exp1] -= ee ee = 0 if sign == 1: newd[2*c*cosh(x/2)] += m else: newd[-2*c*sinh(x/2)] += m elif newd[1 - sign*S.Exp1**x] == -m: # tanh del newd[1 - sign*S.Exp1**x] if sign == 1: newd[-c/tanh(x/2)] += m else: newd[-c*tanh(x/2)] += m else: newd[1 + sign*S.Exp1**x] += m newd[c] += m return Mul(*[k**newd[k] for k in newd]) newexpr = bottom_up(newexpr, f) # sin/cos and sinh/cosh ratios to tan and tanh, respectively if newexpr.has(HyperbolicFunction): e, f = hyper_as_trig(newexpr) newexpr = f(TR2i(e)) if newexpr.has(TrigonometricFunction): newexpr = TR2i(newexpr) # can we ever generate an I where there was none previously? if not (newexpr.has(I) and not expr.has(I)): expr = newexpr return expr #-------------------- the old trigsimp routines --------------------- def trigsimp_old(expr, **opts): """ reduces expression by using known trig identities Notes ===== deep: - Apply trigsimp inside all objects with arguments recursive: - Use common subexpression elimination (cse()) and apply trigsimp recursively (this is quite expensive if the expression is large) method: - Determine the method to use. Valid choices are 'matching' (default), 'groebner', 'combined', 'fu' and 'futrig'. If 'matching', simplify the expression recursively by pattern matching. If 'groebner', apply an experimental groebner basis algorithm. In this case further options are forwarded to ``trigsimp_groebner``, please refer to its docstring. If 'combined', first run the groebner basis algorithm with small default parameters, then run the 'matching' algorithm. 'fu' runs the collection of trigonometric transformations described by Fu, et al. (see the `fu` docstring) while `futrig` runs a subset of Fu-transforms that mimic the behavior of `trigsimp`. compare: - show input and output from `trigsimp` and `futrig` when different, but returns the `trigsimp` value. Examples ======== >>> from sympy import trigsimp, sin, cos, log, cosh, sinh, tan, cot >>> from sympy.abc import x, y >>> e = 2*sin(x)**2 + 2*cos(x)**2 >>> trigsimp(e, old=True) 2 >>> trigsimp(log(e), old=True) log(2*sin(x)**2 + 2*cos(x)**2) >>> trigsimp(log(e), deep=True, old=True) log(2) Using `method="groebner"` (or `"combined"`) can sometimes lead to a lot more simplification: >>> e = (-sin(x) + 1)/cos(x) + cos(x)/(-sin(x) + 1) >>> trigsimp(e, old=True) (-sin(x) + 1)/cos(x) + cos(x)/(-sin(x) + 1) >>> trigsimp(e, method="groebner", old=True) 2/cos(x) >>> trigsimp(1/cot(x)**2, compare=True, old=True) futrig: tan(x)**2 cot(x)**(-2) """ old = expr first = opts.pop('first', True) if first: if not expr.has(*_trigs): return expr trigsyms = set().union(*[t.free_symbols for t in expr.atoms(*_trigs)]) if len(trigsyms) > 1: from sympy.simplify.simplify import separatevars d = separatevars(expr) if d.is_Mul: d = separatevars(d, dict=True) or d if isinstance(d, dict): expr = 1 for k, v in d.items(): # remove hollow factoring was = v v = expand_mul(v) opts['first'] = False vnew = trigsimp(v, **opts) if vnew == v: vnew = was expr *= vnew old = expr else: if d.is_Add: for s in trigsyms: r, e = expr.as_independent(s) if r: opts['first'] = False expr = r + trigsimp(e, **opts) if not expr.is_Add: break old = expr recursive = opts.pop('recursive', False) deep = opts.pop('deep', False) method = opts.pop('method', 'matching') def groebnersimp(ex, deep, **opts): def traverse(e): if e.is_Atom: return e args = [traverse(x) for x in e.args] if e.is_Function or e.is_Pow: args = [trigsimp_groebner(x, **opts) for x in args] return e.func(*args) if deep: ex = traverse(ex) return trigsimp_groebner(ex, **opts) trigsimpfunc = { 'matching': (lambda x, d: _trigsimp(x, d)), 'groebner': (lambda x, d: groebnersimp(x, d, **opts)), 'combined': (lambda x, d: _trigsimp(groebnersimp(x, d, polynomial=True, hints=[2, tan]), d)) }[method] if recursive: w, g = cse(expr) g = trigsimpfunc(g[0], deep) for sub in reversed(w): g = g.subs(sub[0], sub[1]) g = trigsimpfunc(g, deep) result = g else: result = trigsimpfunc(expr, deep) if opts.get('compare', False): f = futrig(old) if f != result: print('\tfutrig:', f) return result def _dotrig(a, b): """Helper to tell whether ``a`` and ``b`` have the same sorts of symbols in them -- no need to test hyperbolic patterns against expressions that have no hyperbolics in them.""" return a.func == b.func and ( a.has(TrigonometricFunction) and b.has(TrigonometricFunction) or a.has(HyperbolicFunction) and b.has(HyperbolicFunction)) _trigpat = None def _trigpats(): global _trigpat a, b, c = symbols('a b c', cls=Wild) d = Wild('d', commutative=False) # for the simplifications like sinh/cosh -> tanh: # DO NOT REORDER THE FIRST 14 since these are assumed to be in this # order in _match_div_rewrite. matchers_division = ( (a*sin(b)**c/cos(b)**c, a*tan(b)**c, sin(b), cos(b)), (a*tan(b)**c*cos(b)**c, a*sin(b)**c, sin(b), cos(b)), (a*cot(b)**c*sin(b)**c, a*cos(b)**c, sin(b), cos(b)), (a*tan(b)**c/sin(b)**c, a/cos(b)**c, sin(b), cos(b)), (a*cot(b)**c/cos(b)**c, a/sin(b)**c, sin(b), cos(b)), (a*cot(b)**c*tan(b)**c, a, sin(b), cos(b)), (a*(cos(b) + 1)**c*(cos(b) - 1)**c, a*(-sin(b)**2)**c, cos(b) + 1, cos(b) - 1), (a*(sin(b) + 1)**c*(sin(b) - 1)**c, a*(-cos(b)**2)**c, sin(b) + 1, sin(b) - 1), (a*sinh(b)**c/cosh(b)**c, a*tanh(b)**c, S.One, S.One), (a*tanh(b)**c*cosh(b)**c, a*sinh(b)**c, S.One, S.One), (a*coth(b)**c*sinh(b)**c, a*cosh(b)**c, S.One, S.One), (a*tanh(b)**c/sinh(b)**c, a/cosh(b)**c, S.One, S.One), (a*coth(b)**c/cosh(b)**c, a/sinh(b)**c, S.One, S.One), (a*coth(b)**c*tanh(b)**c, a, S.One, S.One), (c*(tanh(a) + tanh(b))/(1 + tanh(a)*tanh(b)), tanh(a + b)*c, S.One, S.One), ) matchers_add = ( (c*sin(a)*cos(b) + c*cos(a)*sin(b) + d, sin(a + b)*c + d), (c*cos(a)*cos(b) - c*sin(a)*sin(b) + d, cos(a + b)*c + d), (c*sin(a)*cos(b) - c*cos(a)*sin(b) + d, sin(a - b)*c + d), (c*cos(a)*cos(b) + c*sin(a)*sin(b) + d, cos(a - b)*c + d), (c*sinh(a)*cosh(b) + c*sinh(b)*cosh(a) + d, sinh(a + b)*c + d), (c*cosh(a)*cosh(b) + c*sinh(a)*sinh(b) + d, cosh(a + b)*c + d), ) # for cos(x)**2 + sin(x)**2 -> 1 matchers_identity = ( (a*sin(b)**2, a - a*cos(b)**2), (a*tan(b)**2, a*(1/cos(b))**2 - a), (a*cot(b)**2, a*(1/sin(b))**2 - a), (a*sin(b + c), a*(sin(b)*cos(c) + sin(c)*cos(b))), (a*cos(b + c), a*(cos(b)*cos(c) - sin(b)*sin(c))), (a*tan(b + c), a*((tan(b) + tan(c))/(1 - tan(b)*tan(c)))), (a*sinh(b)**2, a*cosh(b)**2 - a), (a*tanh(b)**2, a - a*(1/cosh(b))**2), (a*coth(b)**2, a + a*(1/sinh(b))**2), (a*sinh(b + c), a*(sinh(b)*cosh(c) + sinh(c)*cosh(b))), (a*cosh(b + c), a*(cosh(b)*cosh(c) + sinh(b)*sinh(c))), (a*tanh(b + c), a*((tanh(b) + tanh(c))/(1 + tanh(b)*tanh(c)))), ) # Reduce any lingering artifacts, such as sin(x)**2 changing # to 1-cos(x)**2 when sin(x)**2 was "simpler" artifacts = ( (a - a*cos(b)**2 + c, a*sin(b)**2 + c, cos), (a - a*(1/cos(b))**2 + c, -a*tan(b)**2 + c, cos), (a - a*(1/sin(b))**2 + c, -a*cot(b)**2 + c, sin), (a - a*cosh(b)**2 + c, -a*sinh(b)**2 + c, cosh), (a - a*(1/cosh(b))**2 + c, a*tanh(b)**2 + c, cosh), (a + a*(1/sinh(b))**2 + c, a*coth(b)**2 + c, sinh), # same as above but with noncommutative prefactor (a*d - a*d*cos(b)**2 + c, a*d*sin(b)**2 + c, cos), (a*d - a*d*(1/cos(b))**2 + c, -a*d*tan(b)**2 + c, cos), (a*d - a*d*(1/sin(b))**2 + c, -a*d*cot(b)**2 + c, sin), (a*d - a*d*cosh(b)**2 + c, -a*d*sinh(b)**2 + c, cosh), (a*d - a*d*(1/cosh(b))**2 + c, a*d*tanh(b)**2 + c, cosh), (a*d + a*d*(1/sinh(b))**2 + c, a*d*coth(b)**2 + c, sinh), ) _trigpat = (a, b, c, d, matchers_division, matchers_add, matchers_identity, artifacts) return _trigpat def _replace_mul_fpowxgpow(expr, f, g, rexp, h, rexph): """Helper for _match_div_rewrite. Replace f(b_)**c_*g(b_)**(rexp(c_)) with h(b)**rexph(c) if f(b_) and g(b_) are both positive or if c_ is an integer. """ # assert expr.is_Mul and expr.is_commutative and f != g fargs = defaultdict(int) gargs = defaultdict(int) args = [] for x in expr.args: if x.is_Pow or x.func in (f, g): b, e = x.as_base_exp() if b.is_positive or e.is_integer: if b.func == f: fargs[b.args[0]] += e continue elif b.func == g: gargs[b.args[0]] += e continue args.append(x) common = set(fargs) & set(gargs) hit = False while common: key = common.pop() fe = fargs.pop(key) ge = gargs.pop(key) if fe == rexp(ge): args.append(h(key)**rexph(fe)) hit = True else: fargs[key] = fe gargs[key] = ge if not hit: return expr while fargs: key, e = fargs.popitem() args.append(f(key)**e) while gargs: key, e = gargs.popitem() args.append(g(key)**e) return Mul(*args) _idn = lambda x: x _midn = lambda x: -x _one = lambda x: S.One def _match_div_rewrite(expr, i): """helper for __trigsimp""" if i == 0: expr = _replace_mul_fpowxgpow(expr, sin, cos, _midn, tan, _idn) elif i == 1: expr = _replace_mul_fpowxgpow(expr, tan, cos, _idn, sin, _idn) elif i == 2: expr = _replace_mul_fpowxgpow(expr, cot, sin, _idn, cos, _idn) elif i == 3: expr = _replace_mul_fpowxgpow(expr, tan, sin, _midn, cos, _midn) elif i == 4: expr = _replace_mul_fpowxgpow(expr, cot, cos, _midn, sin, _midn) elif i == 5: expr = _replace_mul_fpowxgpow(expr, cot, tan, _idn, _one, _idn) # i in (6, 7) is skipped elif i == 8: expr = _replace_mul_fpowxgpow(expr, sinh, cosh, _midn, tanh, _idn) elif i == 9: expr = _replace_mul_fpowxgpow(expr, tanh, cosh, _idn, sinh, _idn) elif i == 10: expr = _replace_mul_fpowxgpow(expr, coth, sinh, _idn, cosh, _idn) elif i == 11: expr = _replace_mul_fpowxgpow(expr, tanh, sinh, _midn, cosh, _midn) elif i == 12: expr = _replace_mul_fpowxgpow(expr, coth, cosh, _midn, sinh, _midn) elif i == 13: expr = _replace_mul_fpowxgpow(expr, coth, tanh, _idn, _one, _idn) else: return None return expr def _trigsimp(expr, deep=False): # protect the cache from non-trig patterns; we only allow # trig patterns to enter the cache if expr.has(*_trigs): return __trigsimp(expr, deep) return expr @cacheit def __trigsimp(expr, deep=False): """recursive helper for trigsimp""" from sympy.simplify.fu import TR10i if _trigpat is None: _trigpats() a, b, c, d, matchers_division, matchers_add, \ matchers_identity, artifacts = _trigpat if expr.is_Mul: # do some simplifications like sin/cos -> tan: if not expr.is_commutative: com, nc = expr.args_cnc() expr = _trigsimp(Mul._from_args(com), deep)*Mul._from_args(nc) else: for i, (pattern, simp, ok1, ok2) in enumerate(matchers_division): if not _dotrig(expr, pattern): continue newexpr = _match_div_rewrite(expr, i) if newexpr is not None: if newexpr != expr: expr = newexpr break else: continue # use SymPy matching instead res = expr.match(pattern) if res and res.get(c, 0): if not res[c].is_integer: ok = ok1.subs(res) if not ok.is_positive: continue ok = ok2.subs(res) if not ok.is_positive: continue # if "a" contains any of trig or hyperbolic funcs with # argument "b" then skip the simplification if any(w.args[0] == res[b] for w in res[a].atoms( TrigonometricFunction, HyperbolicFunction)): continue # simplify and finish: expr = simp.subs(res) break # process below if expr.is_Add: args = [] for term in expr.args: if not term.is_commutative: com, nc = term.args_cnc() nc = Mul._from_args(nc) term = Mul._from_args(com) else: nc = S.One term = _trigsimp(term, deep) for pattern, result in matchers_identity: res = term.match(pattern) if res is not None: term = result.subs(res) break args.append(term*nc) if args != expr.args: expr = Add(*args) expr = min(expr, expand(expr), key=count_ops) if expr.is_Add: for pattern, result in matchers_add: if not _dotrig(expr, pattern): continue expr = TR10i(expr) if expr.has(HyperbolicFunction): res = expr.match(pattern) # if "d" contains any trig or hyperbolic funcs with # argument "a" or "b" then skip the simplification; # this isn't perfect -- see tests if res is None or not (a in res and b in res) or any( w.args[0] in (res[a], res[b]) for w in res[d].atoms( TrigonometricFunction, HyperbolicFunction)): continue expr = result.subs(res) break # Reduce any lingering artifacts, such as sin(x)**2 changing # to 1 - cos(x)**2 when sin(x)**2 was "simpler" for pattern, result, ex in artifacts: if not _dotrig(expr, pattern): continue # Substitute a new wild that excludes some function(s) # to help influence a better match. This is because # sometimes, for example, 'a' would match sec(x)**2 a_t = Wild('a', exclude=[ex]) pattern = pattern.subs(a, a_t) result = result.subs(a, a_t) m = expr.match(pattern) was = None while m and was != expr: was = expr if m[a_t] == 0 or \ -m[a_t] in m[c].args or m[a_t] + m[c] == 0: break if d in m and m[a_t]*m[d] + m[c] == 0: break expr = result.subs(m) m = expr.match(pattern) m.setdefault(c, S.Zero) elif expr.is_Mul or expr.is_Pow or deep and expr.args: expr = expr.func(*[_trigsimp(a, deep) for a in expr.args]) try: if not expr.has(*_trigs): raise TypeError e = expr.atoms(exp) new = expr.rewrite(exp, deep=deep) if new == e: raise TypeError fnew = factor(new) if fnew != new: new = sorted([new, factor(new)], key=count_ops)[0] # if all exp that were introduced disappeared then accept it if not (new.atoms(exp) - e): expr = new except TypeError: pass return expr #------------------- end of old trigsimp routines -------------------- def futrig(e, **kwargs): """Return simplified ``e`` using Fu-like transformations. This is not the "Fu" algorithm. This is called by default from ``trigsimp``. By default, hyperbolics subexpressions will be simplified, but this can be disabled by setting ``hyper=False``. Examples ======== >>> from sympy import trigsimp, tan, sinh, tanh >>> from sympy.simplify.trigsimp import futrig >>> from sympy.abc import x >>> trigsimp(1/tan(x)**2) tan(x)**(-2) >>> futrig(sinh(x)/tanh(x)) cosh(x) """ from sympy.simplify.fu import hyper_as_trig from sympy.simplify.simplify import bottom_up e = sympify(e) if not isinstance(e, Basic): return e if not e.args: return e old = e e = bottom_up(e, lambda x: _futrig(x, **kwargs)) if kwargs.pop('hyper', True) and e.has(HyperbolicFunction): e, f = hyper_as_trig(e) e = f(_futrig(e)) if e != old and e.is_Mul and e.args[0].is_Rational: # redistribute leading coeff on 2-arg Add e = Mul(*e.as_coeff_Mul()) return e def _futrig(e, **kwargs): """Helper for futrig.""" from sympy.simplify.fu import ( TR1, TR2, TR3, TR2i, TR10, L, TR10i, TR8, TR6, TR15, TR16, TR111, TR5, TRmorrie, TR11, TR14, TR22, TR12) from sympy.core.compatibility import _nodes if not e.has(TrigonometricFunction): return e if e.is_Mul: coeff, e = e.as_independent(TrigonometricFunction) else: coeff = S.One Lops = lambda x: (L(x), x.count_ops(), _nodes(x), len(x.args), x.is_Add) trigs = lambda x: x.has(TrigonometricFunction) tree = [identity, ( TR3, # canonical angles TR1, # sec-csc -> cos-sin TR12, # expand tan of sum lambda x: _eapply(factor, x, trigs), TR2, # tan-cot -> sin-cos [identity, lambda x: _eapply(_mexpand, x, trigs)], TR2i, # sin-cos ratio -> tan lambda x: _eapply(lambda i: factor(i.normal()), x, trigs), TR14, # factored identities TR5, # sin-pow -> cos_pow TR10, # sin-cos of sums -> sin-cos prod TR11, TR6, # reduce double angles and rewrite cos pows lambda x: _eapply(factor, x, trigs), TR14, # factored powers of identities [identity, lambda x: _eapply(_mexpand, x, trigs)], TR10i, # sin-cos products > sin-cos of sums TRmorrie, [identity, TR8], # sin-cos products -> sin-cos of sums [identity, lambda x: TR2i(TR2(x))], # tan -> sin-cos -> tan [ lambda x: _eapply(expand_mul, TR5(x), trigs), lambda x: _eapply( expand_mul, TR15(x), trigs)], # pos/neg powers of sin [ lambda x: _eapply(expand_mul, TR6(x), trigs), lambda x: _eapply( expand_mul, TR16(x), trigs)], # pos/neg powers of cos TR111, # tan, sin, cos to neg power -> cot, csc, sec [identity, TR2i], # sin-cos ratio to tan [identity, lambda x: _eapply( expand_mul, TR22(x), trigs)], # tan-cot to sec-csc TR1, TR2, TR2i, [identity, lambda x: _eapply( factor_terms, TR12(x), trigs)], # expand tan of sum )] e = greedy(tree, objective=Lops)(e) return coeff*e def _is_Expr(e): """_eapply helper to tell whether ``e`` and all its args are Exprs.""" from sympy import Derivative if isinstance(e, Derivative): return _is_Expr(e.expr) if not isinstance(e, Expr): return False return all(_is_Expr(i) for i in e.args) def _eapply(func, e, cond=None): """Apply ``func`` to ``e`` if all args are Exprs else only apply it to those args that *are* Exprs.""" if not isinstance(e, Expr): return e if _is_Expr(e) or not e.args: return func(e) return e.func(*[ _eapply(func, ei) if (cond is None or cond(ei)) else ei for ei in e.args])

6d40b9971893432048058213f50e5f1d6e0d2b150ed7644d4a2b99338198d634

""" Tools for doing common subexpression elimination. """ from __future__ import print_function, division from sympy.core import Basic, Mul, Add, Pow, sympify, Symbol from sympy.core.compatibility import iterable, range from sympy.core.containers import Tuple, OrderedSet from sympy.core.exprtools import factor_terms from sympy.core.function import _coeff_isneg from sympy.core.singleton import S from sympy.utilities.iterables import numbered_symbols, sift, \ topological_sort, ordered from . import cse_opts # (preprocessor, postprocessor) pairs which are commonly useful. They should # each take a sympy expression and return a possibly transformed expression. # When used in the function ``cse()``, the target expressions will be transformed # by each of the preprocessor functions in order. After the common # subexpressions are eliminated, each resulting expression will have the # postprocessor functions transform them in *reverse* order in order to undo the # transformation if necessary. This allows the algorithm to operate on # a representation of the expressions that allows for more optimization # opportunities. # ``None`` can be used to specify no transformation for either the preprocessor or # postprocessor. basic_optimizations = [(cse_opts.sub_pre, cse_opts.sub_post), (factor_terms, None)] # sometimes we want the output in a different format; non-trivial # transformations can be put here for users # =============================================================== def reps_toposort(r): """Sort replacements `r` so (k1, v1) appears before (k2, v2) if k2 is in v1's free symbols. This orders items in the way that cse returns its results (hence, in order to use the replacements in a substitution option it would make sense to reverse the order). Examples ======== >>> from sympy.simplify.cse_main import reps_toposort >>> from sympy.abc import x, y >>> from sympy import Eq >>> for l, r in reps_toposort([(x, y + 1), (y, 2)]): ... print(Eq(l, r)) ... Eq(y, 2) Eq(x, y + 1) """ r = sympify(r) E = [] for c1, (k1, v1) in enumerate(r): for c2, (k2, v2) in enumerate(r): if k1 in v2.free_symbols: E.append((c1, c2)) return [r[i] for i in topological_sort((range(len(r)), E))] def cse_separate(r, e): """Move expressions that are in the form (symbol, expr) out of the expressions and sort them into the replacements using the reps_toposort. Examples ======== >>> from sympy.simplify.cse_main import cse_separate >>> from sympy.abc import x, y, z >>> from sympy import cos, exp, cse, Eq, symbols >>> x0, x1 = symbols('x:2') >>> eq = (x + 1 + exp((x + 1)/(y + 1)) + cos(y + 1)) >>> cse([eq, Eq(x, z + 1), z - 2], postprocess=cse_separate) in [ ... [[(x0, y + 1), (x, z + 1), (x1, x + 1)], ... [x1 + exp(x1/x0) + cos(x0), z - 2]], ... [[(x1, y + 1), (x, z + 1), (x0, x + 1)], ... [x0 + exp(x0/x1) + cos(x1), z - 2]]] ... True """ d = sift(e, lambda w: w.is_Equality and w.lhs.is_Symbol) r = r + [w.args for w in d[True]] e = d[False] return [reps_toposort(r), e] # ====end of cse postprocess idioms=========================== def preprocess_for_cse(expr, optimizations): """ Preprocess an expression to optimize for common subexpression elimination. Parameters ========== expr : sympy expression The target expression to optimize. optimizations : list of (callable, callable) pairs The (preprocessor, postprocessor) pairs. Returns ======= expr : sympy expression The transformed expression. """ for pre, post in optimizations: if pre is not None: expr = pre(expr) return expr def postprocess_for_cse(expr, optimizations): """ Postprocess an expression after common subexpression elimination to return the expression to canonical sympy form. Parameters ========== expr : sympy expression The target expression to transform. optimizations : list of (callable, callable) pairs, optional The (preprocessor, postprocessor) pairs. The postprocessors will be applied in reversed order to undo the effects of the preprocessors correctly. Returns ======= expr : sympy expression The transformed expression. """ for pre, post in reversed(optimizations): if post is not None: expr = post(expr) return expr class FuncArgTracker(object): """ A class which manages a mapping from functions to arguments and an inverse mapping from arguments to functions. """ def __init__(self, funcs): # To minimize the number of symbolic comparisons, all function arguments # get assigned a value number. self.value_numbers = {} self.value_number_to_value = [] # Both of these maps use integer indices for arguments / functions. self.arg_to_funcset = [] self.func_to_argset = [] for func_i, func in enumerate(funcs): func_argset = OrderedSet() for func_arg in func.args: arg_number = self.get_or_add_value_number(func_arg) func_argset.add(arg_number) self.arg_to_funcset[arg_number].add(func_i) self.func_to_argset.append(func_argset) def get_args_in_value_order(self, argset): """ Return the list of arguments in sorted order according to their value numbers. """ return [self.value_number_to_value[argn] for argn in sorted(argset)] def get_or_add_value_number(self, value): """ Return the value number for the given argument. """ nvalues = len(self.value_numbers) value_number = self.value_numbers.setdefault(value, nvalues) if value_number == nvalues: self.value_number_to_value.append(value) self.arg_to_funcset.append(OrderedSet()) return value_number def stop_arg_tracking(self, func_i): """ Remove the function func_i from the argument to function mapping. """ for arg in self.func_to_argset[func_i]: self.arg_to_funcset[arg].remove(func_i) def get_common_arg_candidates(self, argset, min_func_i=0): """Return a dict whose keys are function numbers. The entries of the dict are the number of arguments said function has in common with `argset`. Entries have at least 2 items in common. All keys have value at least `min_func_i`. """ from collections import defaultdict count_map = defaultdict(lambda: 0) funcsets = [self.arg_to_funcset[arg] for arg in argset] # As an optimization below, we handle the largest funcset separately from # the others. largest_funcset = max(funcsets, key=len) for funcset in funcsets: if largest_funcset is funcset: continue for func_i in funcset: if func_i >= min_func_i: count_map[func_i] += 1 # We pick the smaller of the two containers (count_map, largest_funcset) # to iterate over to reduce the number of iterations needed. (smaller_funcs_container, larger_funcs_container) = sorted( [largest_funcset, count_map], key=len) for func_i in smaller_funcs_container: # Not already in count_map? It can't possibly be in the output, so # skip it. if count_map[func_i] < 1: continue if func_i in larger_funcs_container: count_map[func_i] += 1 return dict((k, v) for k, v in count_map.items() if v >= 2) def get_subset_candidates(self, argset, restrict_to_funcset=None): """ Return a set of functions each of which whose argument list contains ``argset``, optionally filtered only to contain functions in ``restrict_to_funcset``. """ iarg = iter(argset) indices = OrderedSet( fi for fi in self.arg_to_funcset[next(iarg)]) if restrict_to_funcset is not None: indices &= restrict_to_funcset for arg in iarg: indices &= self.arg_to_funcset[arg] return indices def update_func_argset(self, func_i, new_argset): """ Update a function with a new set of arguments. """ new_args = OrderedSet(new_argset) old_args = self.func_to_argset[func_i] for deleted_arg in old_args - new_args: self.arg_to_funcset[deleted_arg].remove(func_i) for added_arg in new_args - old_args: self.arg_to_funcset[added_arg].add(func_i) self.func_to_argset[func_i].clear() self.func_to_argset[func_i].update(new_args) class Unevaluated(object): def __init__(self, func, args): self.func = func self.args = args def __str__(self): return "Uneval<{}>({})".format( self.func, ", ".join(str(a) for a in self.args)) def as_unevaluated_basic(self): return self.func(*self.args, evaluate=False) @property def free_symbols(self): return set().union(*[a.free_symbols for a in self.args]) __repr__ = __str__ def match_common_args(func_class, funcs, opt_subs): """ Recognize and extract common subexpressions of function arguments within a set of function calls. For instance, for the following function calls:: x + z + y sin(x + y) this will extract a common subexpression of `x + y`:: w = x + y w + z sin(w) The function we work with is assumed to be associative and commutative. Parameters ========== func_class: class The function class (e.g. Add, Mul) funcs: list of functions A list of function calls opt_subs: dict A dictionary of substitutions which this function may update """ # Sort to ensure that whole-function subexpressions come before the items # that use them. funcs = sorted(funcs, key=lambda f: len(f.args)) arg_tracker = FuncArgTracker(funcs) changed = OrderedSet() for i in range(len(funcs)): common_arg_candidates_counts = arg_tracker.get_common_arg_candidates( arg_tracker.func_to_argset[i], min_func_i=i + 1) # Sort the candidates in order of match size. # This makes us try combining smaller matches first. common_arg_candidates = OrderedSet(sorted( common_arg_candidates_counts.keys(), key=lambda k: (common_arg_candidates_counts[k], k))) while common_arg_candidates: j = common_arg_candidates.pop(last=False) com_args = arg_tracker.func_to_argset[i].intersection( arg_tracker.func_to_argset[j]) if len(com_args) <= 1: # This may happen if a set of common arguments was already # combined in a previous iteration. continue # For all sets, replace the common symbols by the function # over them, to allow recursive matches. diff_i = arg_tracker.func_to_argset[i].difference(com_args) if diff_i: # com_func needs to be unevaluated to allow for recursive matches. com_func = Unevaluated( func_class, arg_tracker.get_args_in_value_order(com_args)) com_func_number = arg_tracker.get_or_add_value_number(com_func) arg_tracker.update_func_argset(i, diff_i | OrderedSet([com_func_number])) changed.add(i) else: # Treat the whole expression as a CSE. # # The reason this needs to be done is somewhat subtle. Within # tree_cse(), to_eliminate only contains expressions that are # seen more than once. The problem is unevaluated expressions # do not compare equal to the evaluated equivalent. So # tree_cse() won't mark funcs[i] as a CSE if we use an # unevaluated version. com_func = funcs[i] com_func_number = arg_tracker.get_or_add_value_number(funcs[i]) diff_j = arg_tracker.func_to_argset[j].difference(com_args) arg_tracker.update_func_argset(j, diff_j | OrderedSet([com_func_number])) changed.add(j) for k in arg_tracker.get_subset_candidates( com_args, common_arg_candidates): diff_k = arg_tracker.func_to_argset[k].difference(com_args) arg_tracker.update_func_argset(k, diff_k | OrderedSet([com_func_number])) changed.add(k) if i in changed: opt_subs[funcs[i]] = Unevaluated(func_class, arg_tracker.get_args_in_value_order(arg_tracker.func_to_argset[i])) arg_tracker.stop_arg_tracking(i) def opt_cse(exprs, order='canonical'): """Find optimization opportunities in Adds, Muls, Pows and negative coefficient Muls Parameters ========== exprs : list of sympy expressions The expressions to optimize. order : string, 'none' or 'canonical' The order by which Mul and Add arguments are processed. For large expressions where speed is a concern, use the setting order='none'. Returns ======= opt_subs : dictionary of expression substitutions The expression substitutions which can be useful to optimize CSE. Examples ======== >>> from sympy.simplify.cse_main import opt_cse >>> from sympy.abc import x >>> opt_subs = opt_cse([x**-2]) >>> k, v = list(opt_subs.keys())[0], list(opt_subs.values())[0] >>> print((k, v.as_unevaluated_basic())) (x**(-2), 1/(x**2)) """ from sympy.matrices.expressions import MatAdd, MatMul, MatPow opt_subs = dict() adds = OrderedSet() muls = OrderedSet() seen_subexp = set() def _find_opts(expr): if not isinstance(expr, (Basic, Unevaluated)): return if expr.is_Atom or expr.is_Order: return if iterable(expr): list(map(_find_opts, expr)) return if expr in seen_subexp: return expr seen_subexp.add(expr) list(map(_find_opts, expr.args)) if _coeff_isneg(expr): neg_expr = -expr if not neg_expr.is_Atom: opt_subs[expr] = Unevaluated(Mul, (S.NegativeOne, neg_expr)) seen_subexp.add(neg_expr) expr = neg_expr if isinstance(expr, (Mul, MatMul)): muls.add(expr) elif isinstance(expr, (Add, MatAdd)): adds.add(expr) elif isinstance(expr, (Pow, MatPow)): base, exp = expr.base, expr.exp if _coeff_isneg(exp): opt_subs[expr] = Unevaluated(Pow, (Pow(base, -exp), -1)) for e in exprs: if isinstance(e, (Basic, Unevaluated)): _find_opts(e) # split muls into commutative commutative_muls = OrderedSet() for m in muls: c, nc = m.args_cnc(cset=False) if c: c_mul = m.func(*c) if nc: if c_mul == 1: new_obj = m.func(*nc) else: new_obj = m.func(c_mul, m.func(*nc), evaluate=False) opt_subs[m] = new_obj if len(c) > 1: commutative_muls.add(c_mul) match_common_args(Add, adds, opt_subs) match_common_args(Mul, commutative_muls, opt_subs) return opt_subs def tree_cse(exprs, symbols, opt_subs=None, order='canonical', ignore=()): """Perform raw CSE on expression tree, taking opt_subs into account. Parameters ========== exprs : list of sympy expressions The expressions to reduce. symbols : infinite iterator yielding unique Symbols The symbols used to label the common subexpressions which are pulled out. opt_subs : dictionary of expression substitutions The expressions to be substituted before any CSE action is performed. order : string, 'none' or 'canonical' The order by which Mul and Add arguments are processed. For large expressions where speed is a concern, use the setting order='none'. ignore : iterable of Symbols Substitutions containing any Symbol from ``ignore`` will be ignored. """ from sympy.matrices.expressions import MatrixExpr, MatrixSymbol, MatMul, MatAdd if opt_subs is None: opt_subs = dict() ## Find repeated sub-expressions to_eliminate = set() seen_subexp = set() excluded_symbols = set() def _find_repeated(expr): if not isinstance(expr, (Basic, Unevaluated)): return if isinstance(expr, Basic) and (expr.is_Atom or expr.is_Order): if expr.is_Symbol: excluded_symbols.add(expr) return if iterable(expr): args = expr else: if expr in seen_subexp: for ign in ignore: if ign in expr.free_symbols: break else: to_eliminate.add(expr) return seen_subexp.add(expr) if expr in opt_subs: expr = opt_subs[expr] args = expr.args list(map(_find_repeated, args)) for e in exprs: if isinstance(e, Basic): _find_repeated(e) ## Rebuild tree # Remove symbols from the generator that conflict with names in the expressions. symbols = (symbol for symbol in symbols if symbol not in excluded_symbols) replacements = [] subs = dict() def _rebuild(expr): if not isinstance(expr, (Basic, Unevaluated)): return expr if not expr.args: return expr if iterable(expr): new_args = [_rebuild(arg) for arg in expr] return expr.func(*new_args) if expr in subs: return subs[expr] orig_expr = expr if expr in opt_subs: expr = opt_subs[expr] # If enabled, parse Muls and Adds arguments by order to ensure # replacement order independent from hashes if order != 'none': if isinstance(expr, (Mul, MatMul)): c, nc = expr.args_cnc() if c == [1]: args = nc else: args = list(ordered(c)) + nc elif isinstance(expr, (Add, MatAdd)): args = list(ordered(expr.args)) else: args = expr.args else: args = expr.args new_args = list(map(_rebuild, args)) if isinstance(expr, Unevaluated) or new_args != args: new_expr = expr.func(*new_args) else: new_expr = expr if orig_expr in to_eliminate: try: sym = next(symbols) except StopIteration: raise ValueError("Symbols iterator ran out of symbols.") if isinstance(orig_expr, MatrixExpr): sym = MatrixSymbol(sym.name, orig_expr.rows, orig_expr.cols) subs[orig_expr] = sym replacements.append((sym, new_expr)) return sym else: return new_expr reduced_exprs = [] for e in exprs: if isinstance(e, Basic): reduced_e = _rebuild(e) else: reduced_e = e reduced_exprs.append(reduced_e) return replacements, reduced_exprs def cse(exprs, symbols=None, optimizations=None, postprocess=None, order='canonical', ignore=()): """ Perform common subexpression elimination on an expression. Parameters ========== exprs : list of sympy expressions, or a single sympy expression The expressions to reduce. symbols : infinite iterator yielding unique Symbols The symbols used to label the common subexpressions which are pulled out. The ``numbered_symbols`` generator is useful. The default is a stream of symbols of the form "x0", "x1", etc. This must be an infinite iterator. optimizations : list of (callable, callable) pairs The (preprocessor, postprocessor) pairs of external optimization functions. Optionally 'basic' can be passed for a set of predefined basic optimizations. Such 'basic' optimizations were used by default in old implementation, however they can be really slow on larger expressions. Now, no pre or post optimizations are made by default. postprocess : a function which accepts the two return values of cse and returns the desired form of output from cse, e.g. if you want the replacements reversed the function might be the following lambda: lambda r, e: return reversed(r), e order : string, 'none' or 'canonical' The order by which Mul and Add arguments are processed. If set to 'canonical', arguments will be canonically ordered. If set to 'none', ordering will be faster but dependent on expressions hashes, thus machine dependent and variable. For large expressions where speed is a concern, use the setting order='none'. ignore : iterable of Symbols Substitutions containing any Symbol from ``ignore`` will be ignored. Returns ======= replacements : list of (Symbol, expression) pairs All of the common subexpressions that were replaced. Subexpressions earlier in this list might show up in subexpressions later in this list. reduced_exprs : list of sympy expressions The reduced expressions with all of the replacements above. Examples ======== >>> from sympy import cse, SparseMatrix >>> from sympy.abc import x, y, z, w >>> cse(((w + x + y + z)*(w + y + z))/(w + x)**3) ([(x0, y + z), (x1, w + x)], [(w + x0)*(x0 + x1)/x1**3]) Note that currently, y + z will not get substituted if -y - z is used. >>> cse(((w + x + y + z)*(w - y - z))/(w + x)**3) ([(x0, w + x)], [(w - y - z)*(x0 + y + z)/x0**3]) List of expressions with recursive substitutions: >>> m = SparseMatrix([x + y, x + y + z]) >>> cse([(x+y)**2, x + y + z, y + z, x + z + y, m]) ([(x0, x + y), (x1, x0 + z)], [x0**2, x1, y + z, x1, Matrix([ [x0], [x1]])]) Note: the type and mutability of input matrices is retained. >>> isinstance(_[1][-1], SparseMatrix) True The user may disallow substitutions containing certain symbols: >>> cse([y**2*(x + 1), 3*y**2*(x + 1)], ignore=(y,)) ([(x0, x + 1)], [x0*y**2, 3*x0*y**2]) """ from sympy.matrices import (MatrixBase, Matrix, ImmutableMatrix, SparseMatrix, ImmutableSparseMatrix) if isinstance(exprs, (int, float)): exprs = sympify(exprs) # Handle the case if just one expression was passed. if isinstance(exprs, (Basic, MatrixBase)): exprs = [exprs] copy = exprs temp = [] for e in exprs: if isinstance(e, (Matrix, ImmutableMatrix)): temp.append(Tuple(*e._mat)) elif isinstance(e, (SparseMatrix, ImmutableSparseMatrix)): temp.append(Tuple(*e._smat.items())) else: temp.append(e) exprs = temp del temp if optimizations is None: optimizations = list() elif optimizations == 'basic': optimizations = basic_optimizations # Preprocess the expressions to give us better optimization opportunities. reduced_exprs = [preprocess_for_cse(e, optimizations) for e in exprs] if symbols is None: symbols = numbered_symbols(cls=Symbol) else: # In case we get passed an iterable with an __iter__ method instead of # an actual iterator. symbols = iter(symbols) # Find other optimization opportunities. opt_subs = opt_cse(reduced_exprs, order) # Main CSE algorithm. replacements, reduced_exprs = tree_cse(reduced_exprs, symbols, opt_subs, order, ignore) # Postprocess the expressions to return the expressions to canonical form. exprs = copy for i, (sym, subtree) in enumerate(replacements): subtree = postprocess_for_cse(subtree, optimizations) replacements[i] = (sym, subtree) reduced_exprs = [postprocess_for_cse(e, optimizations) for e in reduced_exprs] # Get the matrices back for i, e in enumerate(exprs): if isinstance(e, (Matrix, ImmutableMatrix)): reduced_exprs[i] = Matrix(e.rows, e.cols, reduced_exprs[i]) if isinstance(e, ImmutableMatrix): reduced_exprs[i] = reduced_exprs[i].as_immutable() elif isinstance(e, (SparseMatrix, ImmutableSparseMatrix)): m = SparseMatrix(e.rows, e.cols, {}) for k, v in reduced_exprs[i]: m[k] = v if isinstance(e, ImmutableSparseMatrix): m = m.as_immutable() reduced_exprs[i] = m if postprocess is None: return replacements, reduced_exprs return postprocess(replacements, reduced_exprs)

8d324c97d3ebc94a6b3d68e9297986e235cb789a1e6db3cca127eb285e44666c

""" Implementation of the trigsimp algorithm by Fu et al. The idea behind the ``fu`` algorithm is to use a sequence of rules, applied in what is heuristically known to be a smart order, to select a simpler expression that is equivalent to the input. There are transform rules in which a single rule is applied to the expression tree. The following are just mnemonic in nature; see the docstrings for examples. TR0 - simplify expression TR1 - sec-csc to cos-sin TR2 - tan-cot to sin-cos ratio TR2i - sin-cos ratio to tan TR3 - angle canonicalization TR4 - functions at special angles TR5 - powers of sin to powers of cos TR6 - powers of cos to powers of sin TR7 - reduce cos power (increase angle) TR8 - expand products of sin-cos to sums TR9 - contract sums of sin-cos to products TR10 - separate sin-cos arguments TR10i - collect sin-cos arguments TR11 - reduce double angles TR12 - separate tan arguments TR12i - collect tan arguments TR13 - expand product of tan-cot TRmorrie - prod(cos(x*2**i), (i, 0, k - 1)) -> sin(2**k*x)/(2**k*sin(x)) TR14 - factored powers of sin or cos to cos or sin power TR15 - negative powers of sin to cot power TR16 - negative powers of cos to tan power TR22 - tan-cot powers to negative powers of sec-csc functions TR111 - negative sin-cos-tan powers to csc-sec-cot There are 4 combination transforms (CTR1 - CTR4) in which a sequence of transformations are applied and the simplest expression is selected from a few options. Finally, there are the 2 rule lists (RL1 and RL2), which apply a sequence of transformations and combined transformations, and the ``fu`` algorithm itself, which applies rules and rule lists and selects the best expressions. There is also a function ``L`` which counts the number of trigonometric functions that appear in the expression. Other than TR0, re-writing of expressions is not done by the transformations. e.g. TR10i finds pairs of terms in a sum that are in the form like ``cos(x)*cos(y) + sin(x)*sin(y)``. Such expression are targeted in a bottom-up traversal of the expression, but no manipulation to make them appear is attempted. For example, Set-up for examples below: >>> from sympy.simplify.fu import fu, L, TR9, TR10i, TR11 >>> from sympy import factor, sin, cos, powsimp >>> from sympy.abc import x, y, z, a >>> from time import time >>> eq = cos(x + y)/cos(x) >>> TR10i(eq.expand(trig=True)) -sin(x)*sin(y)/cos(x) + cos(y) If the expression is put in "normal" form (with a common denominator) then the transformation is successful: >>> TR10i(_.normal()) cos(x + y)/cos(x) TR11's behavior is similar. It rewrites double angles as smaller angles but doesn't do any simplification of the result. >>> TR11(sin(2)**a*cos(1)**(-a), 1) (2*sin(1)*cos(1))**a*cos(1)**(-a) >>> powsimp(_) (2*sin(1))**a The temptation is to try make these TR rules "smarter" but that should really be done at a higher level; the TR rules should try maintain the "do one thing well" principle. There is one exception, however. In TR10i and TR9 terms are recognized even when they are each multiplied by a common factor: >>> fu(a*cos(x)*cos(y) + a*sin(x)*sin(y)) a*cos(x - y) Factoring with ``factor_terms`` is used but it it "JIT"-like, being delayed until it is deemed necessary. Furthermore, if the factoring does not help with the simplification, it is not retained, so ``a*cos(x)*cos(y) + a*sin(x)*sin(z)`` does not become the factored (but unsimplified in the trigonometric sense) expression: >>> fu(a*cos(x)*cos(y) + a*sin(x)*sin(z)) a*sin(x)*sin(z) + a*cos(x)*cos(y) In some cases factoring might be a good idea, but the user is left to make that decision. For example: >>> expr=((15*sin(2*x) + 19*sin(x + y) + 17*sin(x + z) + 19*cos(x - z) + ... 25)*(20*sin(2*x) + 15*sin(x + y) + sin(y + z) + 14*cos(x - z) + ... 14*cos(y - z))*(9*sin(2*y) + 12*sin(y + z) + 10*cos(x - y) + 2*cos(y - ... z) + 18)).expand(trig=True).expand() In the expanded state, there are nearly 1000 trig functions: >>> L(expr) 932 If the expression where factored first, this would take time but the resulting expression would be transformed very quickly: >>> def clock(f, n=2): ... t=time(); f(); return round(time()-t, n) ... >>> clock(lambda: factor(expr)) # doctest: +SKIP 0.86 >>> clock(lambda: TR10i(expr), 3) # doctest: +SKIP 0.016 If the unexpanded expression is used, the transformation takes longer but not as long as it took to factor it and then transform it: >>> clock(lambda: TR10i(expr), 2) # doctest: +SKIP 0.28 So neither expansion nor factoring is used in ``TR10i``: if the expression is already factored (or partially factored) then expansion with ``trig=True`` would destroy what is already known and take longer; if the expression is expanded, factoring may take longer than simply applying the transformation itself. Although the algorithms should be canonical, always giving the same result, they may not yield the best result. This, in general, is the nature of simplification where searching all possible transformation paths is very expensive. Here is a simple example. There are 6 terms in the following sum: >>> expr = (sin(x)**2*cos(y)*cos(z) + sin(x)*sin(y)*cos(x)*cos(z) + ... sin(x)*sin(z)*cos(x)*cos(y) + sin(y)*sin(z)*cos(x)**2 + sin(y)*sin(z) + ... cos(y)*cos(z)) >>> args = expr.args Serendipitously, fu gives the best result: >>> fu(expr) 3*cos(y - z)/2 - cos(2*x + y + z)/2 But if different terms were combined, a less-optimal result might be obtained, requiring some additional work to get better simplification, but still less than optimal. The following shows an alternative form of ``expr`` that resists optimal simplification once a given step is taken since it leads to a dead end: >>> TR9(-cos(x)**2*cos(y + z) + 3*cos(y - z)/2 + ... cos(y + z)/2 + cos(-2*x + y + z)/4 - cos(2*x + y + z)/4) sin(2*x)*sin(y + z)/2 - cos(x)**2*cos(y + z) + 3*cos(y - z)/2 + cos(y + z)/2 Here is a smaller expression that exhibits the same behavior: >>> a = sin(x)*sin(z)*cos(x)*cos(y) + sin(x)*sin(y)*cos(x)*cos(z) >>> TR10i(a) sin(x)*sin(y + z)*cos(x) >>> newa = _ >>> TR10i(expr - a) # this combines two more of the remaining terms sin(x)**2*cos(y)*cos(z) + sin(y)*sin(z)*cos(x)**2 + cos(y - z) >>> TR10i(_ + newa) == _ + newa # but now there is no more simplification True Without getting lucky or trying all possible pairings of arguments, the final result may be less than optimal and impossible to find without better heuristics or brute force trial of all possibilities. Notes ===== This work was started by Dimitar Vlahovski at the Technological School "Electronic systems" (30.11.2011). References ========== Fu, Hongguang, Xiuqin Zhong, and Zhenbing Zeng. "Automated and readable simplification of trigonometric expressions." Mathematical and computer modelling 44.11 (2006): 1169-1177. http://rfdz.ph-noe.ac.at/fileadmin/Mathematik_Uploads/ACDCA/DESTIME2006/DES_contribs/Fu/simplification.pdf http://www.sosmath.com/trig/Trig5/trig5/pdf/pdf.html gives a formula sheet. """ from __future__ import print_function, division from collections import defaultdict from sympy.core.add import Add from sympy.core.basic import S from sympy.core.compatibility import ordered, range from sympy.core.expr import Expr from sympy.core.exprtools import Factors, gcd_terms, factor_terms from sympy.core.function import expand_mul from sympy.core.mul import Mul from sympy.core.numbers import pi, I from sympy.core.power import Pow from sympy.core.symbol import Dummy from sympy.core.sympify import sympify from sympy.functions.combinatorial.factorials import binomial from sympy.functions.elementary.hyperbolic import ( cosh, sinh, tanh, coth, sech, csch, HyperbolicFunction) from sympy.functions.elementary.trigonometric import ( cos, sin, tan, cot, sec, csc, sqrt, TrigonometricFunction) from sympy.ntheory.factor_ import perfect_power from sympy.polys.polytools import factor from sympy.simplify.simplify import bottom_up from sympy.strategies.tree import greedy from sympy.strategies.core import identity, debug from sympy import SYMPY_DEBUG # ================== Fu-like tools =========================== def TR0(rv): """Simplification of rational polynomials, trying to simplify the expression, e.g. combine things like 3*x + 2*x, etc.... """ # although it would be nice to use cancel, it doesn't work # with noncommutatives return rv.normal().factor().expand() def TR1(rv): """Replace sec, csc with 1/cos, 1/sin Examples ======== >>> from sympy.simplify.fu import TR1, sec, csc >>> from sympy.abc import x >>> TR1(2*csc(x) + sec(x)) 1/cos(x) + 2/sin(x) """ def f(rv): if isinstance(rv, sec): a = rv.args[0] return S.One/cos(a) elif isinstance(rv, csc): a = rv.args[0] return S.One/sin(a) return rv return bottom_up(rv, f) def TR2(rv): """Replace tan and cot with sin/cos and cos/sin Examples ======== >>> from sympy.simplify.fu import TR2 >>> from sympy.abc import x >>> from sympy import tan, cot, sin, cos >>> TR2(tan(x)) sin(x)/cos(x) >>> TR2(cot(x)) cos(x)/sin(x) >>> TR2(tan(tan(x) - sin(x)/cos(x))) 0 """ def f(rv): if isinstance(rv, tan): a = rv.args[0] return sin(a)/cos(a) elif isinstance(rv, cot): a = rv.args[0] return cos(a)/sin(a) return rv return bottom_up(rv, f) def TR2i(rv, half=False): """Converts ratios involving sin and cos as follows:: sin(x)/cos(x) -> tan(x) sin(x)/(cos(x) + 1) -> tan(x/2) if half=True Examples ======== >>> from sympy.simplify.fu import TR2i >>> from sympy.abc import x, a >>> from sympy import sin, cos >>> TR2i(sin(x)/cos(x)) tan(x) Powers of the numerator and denominator are also recognized >>> TR2i(sin(x)**2/(cos(x) + 1)**2, half=True) tan(x/2)**2 The transformation does not take place unless assumptions allow (i.e. the base must be positive or the exponent must be an integer for both numerator and denominator) >>> TR2i(sin(x)**a/(cos(x) + 1)**a) (cos(x) + 1)**(-a)*sin(x)**a """ def f(rv): if not rv.is_Mul: return rv n, d = rv.as_numer_denom() if n.is_Atom or d.is_Atom: return rv def ok(k, e): # initial filtering of factors return ( (e.is_integer or k.is_positive) and ( k.func in (sin, cos) or (half and k.is_Add and len(k.args) >= 2 and any(any(isinstance(ai, cos) or ai.is_Pow and ai.base is cos for ai in Mul.make_args(a)) for a in k.args)))) n = n.as_powers_dict() ndone = [(k, n.pop(k)) for k in list(n.keys()) if not ok(k, n[k])] if not n: return rv d = d.as_powers_dict() ddone = [(k, d.pop(k)) for k in list(d.keys()) if not ok(k, d[k])] if not d: return rv # factoring if necessary def factorize(d, ddone): newk = [] for k in d: if k.is_Add and len(k.args) > 1: knew = factor(k) if half else factor_terms(k) if knew != k: newk.append((k, knew)) if newk: for i, (k, knew) in enumerate(newk): del d[k] newk[i] = knew newk = Mul(*newk).as_powers_dict() for k in newk: v = d[k] + newk[k] if ok(k, v): d[k] = v else: ddone.append((k, v)) del newk factorize(n, ndone) factorize(d, ddone) # joining t = [] for k in n: if isinstance(k, sin): a = cos(k.args[0], evaluate=False) if a in d and d[a] == n[k]: t.append(tan(k.args[0])**n[k]) n[k] = d[a] = None elif half: a1 = 1 + a if a1 in d and d[a1] == n[k]: t.append((tan(k.args[0]/2))**n[k]) n[k] = d[a1] = None elif isinstance(k, cos): a = sin(k.args[0], evaluate=False) if a in d and d[a] == n[k]: t.append(tan(k.args[0])**-n[k]) n[k] = d[a] = None elif half and k.is_Add and k.args[0] is S.One and \ isinstance(k.args[1], cos): a = sin(k.args[1].args[0], evaluate=False) if a in d and d[a] == n[k] and (d[a].is_integer or \ a.is_positive): t.append(tan(a.args[0]/2)**-n[k]) n[k] = d[a] = None if t: rv = Mul(*(t + [b**e for b, e in n.items() if e]))/\ Mul(*[b**e for b, e in d.items() if e]) rv *= Mul(*[b**e for b, e in ndone])/Mul(*[b**e for b, e in ddone]) return rv return bottom_up(rv, f) def TR3(rv): """Induced formula: example sin(-a) = -sin(a) Examples ======== >>> from sympy.simplify.fu import TR3 >>> from sympy.abc import x, y >>> from sympy import pi >>> from sympy import cos >>> TR3(cos(y - x*(y - x))) cos(x*(x - y) + y) >>> cos(pi/2 + x) -sin(x) >>> cos(30*pi/2 + x) -cos(x) """ from sympy.simplify.simplify import signsimp # Negative argument (already automatic for funcs like sin(-x) -> -sin(x) # but more complicated expressions can use it, too). Also, trig angles # between pi/4 and pi/2 are not reduced to an angle between 0 and pi/4. # The following are automatically handled: # Argument of type: pi/2 +/- angle # Argument of type: pi +/- angle # Argument of type : 2k*pi +/- angle def f(rv): if not isinstance(rv, TrigonometricFunction): return rv rv = rv.func(signsimp(rv.args[0])) if not isinstance(rv, TrigonometricFunction): return rv if (rv.args[0] - S.Pi/4).is_positive is (S.Pi/2 - rv.args[0]).is_positive is True: fmap = {cos: sin, sin: cos, tan: cot, cot: tan, sec: csc, csc: sec} rv = fmap[rv.func](S.Pi/2 - rv.args[0]) return rv return bottom_up(rv, f) def TR4(rv): """Identify values of special angles. a= 0 pi/6 pi/4 pi/3 pi/2 ---------------------------------------------------- cos(a) 0 1/2 sqrt(2)/2 sqrt(3)/2 1 sin(a) 1 sqrt(3)/2 sqrt(2)/2 1/2 0 tan(a) 0 sqt(3)/3 1 sqrt(3) -- Examples ======== >>> from sympy.simplify.fu import TR4 >>> from sympy import pi >>> from sympy import cos, sin, tan, cot >>> for s in (0, pi/6, pi/4, pi/3, pi/2): ... print('%s %s %s %s' % (cos(s), sin(s), tan(s), cot(s))) ... 1 0 0 zoo sqrt(3)/2 1/2 sqrt(3)/3 sqrt(3) sqrt(2)/2 sqrt(2)/2 1 1 1/2 sqrt(3)/2 sqrt(3) sqrt(3)/3 0 1 zoo 0 """ # special values at 0, pi/6, pi/4, pi/3, pi/2 already handled return rv def _TR56(rv, f, g, h, max, pow): """Helper for TR5 and TR6 to replace f**2 with h(g**2) Options ======= max : controls size of exponent that can appear on f e.g. if max=4 then f**4 will be changed to h(g**2)**2. pow : controls whether the exponent must be a perfect power of 2 e.g. if pow=True (and max >= 6) then f**6 will not be changed but f**8 will be changed to h(g**2)**4 >>> from sympy.simplify.fu import _TR56 as T >>> from sympy.abc import x >>> from sympy import sin, cos >>> h = lambda x: 1 - x >>> T(sin(x)**3, sin, cos, h, 4, False) sin(x)**3 >>> T(sin(x)**6, sin, cos, h, 6, False) (-cos(x)**2 + 1)**3 >>> T(sin(x)**6, sin, cos, h, 6, True) sin(x)**6 >>> T(sin(x)**8, sin, cos, h, 10, True) (-cos(x)**2 + 1)**4 """ def _f(rv): # I'm not sure if this transformation should target all even powers # or only those expressible as powers of 2. Also, should it only # make the changes in powers that appear in sums -- making an isolated # change is not going to allow a simplification as far as I can tell. if not (rv.is_Pow and rv.base.func == f): return rv if (rv.exp < 0) == True: return rv if (rv.exp > max) == True: return rv if rv.exp == 2: return h(g(rv.base.args[0])**2) else: if rv.exp == 4: e = 2 elif not pow: if rv.exp % 2: return rv e = rv.exp//2 else: p = perfect_power(rv.exp) if not p: return rv e = rv.exp//2 return h(g(rv.base.args[0])**2)**e return bottom_up(rv, _f) def TR5(rv, max=4, pow=False): """Replacement of sin**2 with 1 - cos(x)**2. See _TR56 docstring for advanced use of ``max`` and ``pow``. Examples ======== >>> from sympy.simplify.fu import TR5 >>> from sympy.abc import x >>> from sympy import sin >>> TR5(sin(x)**2) -cos(x)**2 + 1 >>> TR5(sin(x)**-2) # unchanged sin(x)**(-2) >>> TR5(sin(x)**4) (-cos(x)**2 + 1)**2 """ return _TR56(rv, sin, cos, lambda x: 1 - x, max=max, pow=pow) def TR6(rv, max=4, pow=False): """Replacement of cos**2 with 1 - sin(x)**2. See _TR56 docstring for advanced use of ``max`` and ``pow``. Examples ======== >>> from sympy.simplify.fu import TR6 >>> from sympy.abc import x >>> from sympy import cos >>> TR6(cos(x)**2) -sin(x)**2 + 1 >>> TR6(cos(x)**-2) #unchanged cos(x)**(-2) >>> TR6(cos(x)**4) (-sin(x)**2 + 1)**2 """ return _TR56(rv, cos, sin, lambda x: 1 - x, max=max, pow=pow) def TR7(rv): """Lowering the degree of cos(x)**2 Examples ======== >>> from sympy.simplify.fu import TR7 >>> from sympy.abc import x >>> from sympy import cos >>> TR7(cos(x)**2) cos(2*x)/2 + 1/2 >>> TR7(cos(x)**2 + 1) cos(2*x)/2 + 3/2 """ def f(rv): if not (rv.is_Pow and rv.base.func == cos and rv.exp == 2): return rv return (1 + cos(2*rv.base.args[0]))/2 return bottom_up(rv, f) def TR8(rv, first=True): """Converting products of ``cos`` and/or ``sin`` to a sum or difference of ``cos`` and or ``sin`` terms. Examples ======== >>> from sympy.simplify.fu import TR8, TR7 >>> from sympy import cos, sin >>> TR8(cos(2)*cos(3)) cos(5)/2 + cos(1)/2 >>> TR8(cos(2)*sin(3)) sin(5)/2 + sin(1)/2 >>> TR8(sin(2)*sin(3)) -cos(5)/2 + cos(1)/2 """ def f(rv): if not ( rv.is_Mul or rv.is_Pow and rv.base.func in (cos, sin) and (rv.exp.is_integer or rv.base.is_positive)): return rv if first: n, d = [expand_mul(i) for i in rv.as_numer_denom()] newn = TR8(n, first=False) newd = TR8(d, first=False) if newn != n or newd != d: rv = gcd_terms(newn/newd) if rv.is_Mul and rv.args[0].is_Rational and \ len(rv.args) == 2 and rv.args[1].is_Add: rv = Mul(*rv.as_coeff_Mul()) return rv args = {cos: [], sin: [], None: []} for a in ordered(Mul.make_args(rv)): if a.func in (cos, sin): args[a.func].append(a.args[0]) elif (a.is_Pow and a.exp.is_Integer and a.exp > 0 and \ a.base.func in (cos, sin)): # XXX this is ok but pathological expression could be handled # more efficiently as in TRmorrie args[a.base.func].extend([a.base.args[0]]*a.exp) else: args[None].append(a) c = args[cos] s = args[sin] if not (c and s or len(c) > 1 or len(s) > 1): return rv args = args[None] n = min(len(c), len(s)) for i in range(n): a1 = s.pop() a2 = c.pop() args.append((sin(a1 + a2) + sin(a1 - a2))/2) while len(c) > 1: a1 = c.pop() a2 = c.pop() args.append((cos(a1 + a2) + cos(a1 - a2))/2) if c: args.append(cos(c.pop())) while len(s) > 1: a1 = s.pop() a2 = s.pop() args.append((-cos(a1 + a2) + cos(a1 - a2))/2) if s: args.append(sin(s.pop())) return TR8(expand_mul(Mul(*args))) return bottom_up(rv, f) def TR9(rv): """Sum of ``cos`` or ``sin`` terms as a product of ``cos`` or ``sin``. Examples ======== >>> from sympy.simplify.fu import TR9 >>> from sympy import cos, sin >>> TR9(cos(1) + cos(2)) 2*cos(1/2)*cos(3/2) >>> TR9(cos(1) + 2*sin(1) + 2*sin(2)) cos(1) + 4*sin(3/2)*cos(1/2) If no change is made by TR9, no re-arrangement of the expression will be made. For example, though factoring of common term is attempted, if the factored expression wasn't changed, the original expression will be returned: >>> TR9(cos(3) + cos(3)*cos(2)) cos(3) + cos(2)*cos(3) """ def f(rv): if not rv.is_Add: return rv def do(rv, first=True): # cos(a)+/-cos(b) can be combined into a product of cosines and # sin(a)+/-sin(b) can be combined into a product of cosine and # sine. # # If there are more than two args, the pairs which "work" will # have a gcd extractable and the remaining two terms will have # the above structure -- all pairs must be checked to find the # ones that work. args that don't have a common set of symbols # are skipped since this doesn't lead to a simpler formula and # also has the arbitrariness of combining, for example, the x # and y term instead of the y and z term in something like # cos(x) + cos(y) + cos(z). if not rv.is_Add: return rv args = list(ordered(rv.args)) if len(args) != 2: hit = False for i in range(len(args)): ai = args[i] if ai is None: continue for j in range(i + 1, len(args)): aj = args[j] if aj is None: continue was = ai + aj new = do(was) if new != was: args[i] = new # update in place args[j] = None hit = True break # go to next i if hit: rv = Add(*[_f for _f in args if _f]) if rv.is_Add: rv = do(rv) return rv # two-arg Add split = trig_split(*args) if not split: return rv gcd, n1, n2, a, b, iscos = split # application of rule if possible if iscos: if n1 == n2: return gcd*n1*2*cos((a + b)/2)*cos((a - b)/2) if n1 < 0: a, b = b, a return -2*gcd*sin((a + b)/2)*sin((a - b)/2) else: if n1 == n2: return gcd*n1*2*sin((a + b)/2)*cos((a - b)/2) if n1 < 0: a, b = b, a return 2*gcd*cos((a + b)/2)*sin((a - b)/2) return process_common_addends(rv, do) # DON'T sift by free symbols return bottom_up(rv, f) def TR10(rv, first=True): """Separate sums in ``cos`` and ``sin``. Examples ======== >>> from sympy.simplify.fu import TR10 >>> from sympy.abc import a, b, c >>> from sympy import cos, sin >>> TR10(cos(a + b)) -sin(a)*sin(b) + cos(a)*cos(b) >>> TR10(sin(a + b)) sin(a)*cos(b) + sin(b)*cos(a) >>> TR10(sin(a + b + c)) (-sin(a)*sin(b) + cos(a)*cos(b))*sin(c) + \ (sin(a)*cos(b) + sin(b)*cos(a))*cos(c) """ def f(rv): if not rv.func in (cos, sin): return rv f = rv.func arg = rv.args[0] if arg.is_Add: if first: args = list(ordered(arg.args)) else: args = list(arg.args) a = args.pop() b = Add._from_args(args) if b.is_Add: if f == sin: return sin(a)*TR10(cos(b), first=False) + \ cos(a)*TR10(sin(b), first=False) else: return cos(a)*TR10(cos(b), first=False) - \ sin(a)*TR10(sin(b), first=False) else: if f == sin: return sin(a)*cos(b) + cos(a)*sin(b) else: return cos(a)*cos(b) - sin(a)*sin(b) return rv return bottom_up(rv, f) def TR10i(rv): """Sum of products to function of sum. Examples ======== >>> from sympy.simplify.fu import TR10i >>> from sympy import cos, sin, pi, Add, Mul, sqrt, Symbol >>> from sympy.abc import x, y >>> TR10i(cos(1)*cos(3) + sin(1)*sin(3)) cos(2) >>> TR10i(cos(1)*sin(3) + sin(1)*cos(3) + cos(3)) cos(3) + sin(4) >>> TR10i(sqrt(2)*cos(x)*x + sqrt(6)*sin(x)*x) 2*sqrt(2)*x*sin(x + pi/6) """ global _ROOT2, _ROOT3, _invROOT3 if _ROOT2 is None: _roots() def f(rv): if not rv.is_Add: return rv def do(rv, first=True): # args which can be expressed as A*(cos(a)*cos(b)+/-sin(a)*sin(b)) # or B*(cos(a)*sin(b)+/-cos(b)*sin(a)) can be combined into # A*f(a+/-b) where f is either sin or cos. # # If there are more than two args, the pairs which "work" will have # a gcd extractable and the remaining two terms will have the above # structure -- all pairs must be checked to find the ones that # work. if not rv.is_Add: return rv args = list(ordered(rv.args)) if len(args) != 2: hit = False for i in range(len(args)): ai = args[i] if ai is None: continue for j in range(i + 1, len(args)): aj = args[j] if aj is None: continue was = ai + aj new = do(was) if new != was: args[i] = new # update in place args[j] = None hit = True break # go to next i if hit: rv = Add(*[_f for _f in args if _f]) if rv.is_Add: rv = do(rv) return rv # two-arg Add split = trig_split(*args, two=True) if not split: return rv gcd, n1, n2, a, b, same = split # identify and get c1 to be cos then apply rule if possible if same: # coscos, sinsin gcd = n1*gcd if n1 == n2: return gcd*cos(a - b) return gcd*cos(a + b) else: #cossin, cossin gcd = n1*gcd if n1 == n2: return gcd*sin(a + b) return gcd*sin(b - a) rv = process_common_addends( rv, do, lambda x: tuple(ordered(x.free_symbols))) # need to check for inducible pairs in ratio of sqrt(3):1 that # appeared in different lists when sorting by coefficient while rv.is_Add: byrad = defaultdict(list) for a in rv.args: hit = 0 if a.is_Mul: for ai in a.args: if ai.is_Pow and ai.exp is S.Half and \ ai.base.is_Integer: byrad[ai].append(a) hit = 1 break if not hit: byrad[S.One].append(a) # no need to check all pairs -- just check for the onees # that have the right ratio args = [] for a in byrad: for b in [_ROOT3*a, _invROOT3]: if b in byrad: for i in range(len(byrad[a])): if byrad[a][i] is None: continue for j in range(len(byrad[b])): if byrad[b][j] is None: continue was = Add(byrad[a][i] + byrad[b][j]) new = do(was) if new != was: args.append(new) byrad[a][i] = None byrad[b][j] = None break if args: rv = Add(*(args + [Add(*[_f for _f in v if _f]) for v in byrad.values()])) else: rv = do(rv) # final pass to resolve any new inducible pairs break return rv return bottom_up(rv, f) def TR11(rv, base=None): """Function of double angle to product. The ``base`` argument can be used to indicate what is the un-doubled argument, e.g. if 3*pi/7 is the base then cosine and sine functions with argument 6*pi/7 will be replaced. Examples ======== >>> from sympy.simplify.fu import TR11 >>> from sympy import cos, sin, pi >>> from sympy.abc import x >>> TR11(sin(2*x)) 2*sin(x)*cos(x) >>> TR11(cos(2*x)) -sin(x)**2 + cos(x)**2 >>> TR11(sin(4*x)) 4*(-sin(x)**2 + cos(x)**2)*sin(x)*cos(x) >>> TR11(sin(4*x/3)) 4*(-sin(x/3)**2 + cos(x/3)**2)*sin(x/3)*cos(x/3) If the arguments are simply integers, no change is made unless a base is provided: >>> TR11(cos(2)) cos(2) >>> TR11(cos(4), 2) -sin(2)**2 + cos(2)**2 There is a subtle issue here in that autosimplification will convert some higher angles to lower angles >>> cos(6*pi/7) + cos(3*pi/7) -cos(pi/7) + cos(3*pi/7) The 6*pi/7 angle is now pi/7 but can be targeted with TR11 by supplying the 3*pi/7 base: >>> TR11(_, 3*pi/7) -sin(3*pi/7)**2 + cos(3*pi/7)**2 + cos(3*pi/7) """ def f(rv): if not rv.func in (cos, sin): return rv if base: f = rv.func t = f(base*2) co = S.One if t.is_Mul: co, t = t.as_coeff_Mul() if not t.func in (cos, sin): return rv if rv.args[0] == t.args[0]: c = cos(base) s = sin(base) if f is cos: return (c**2 - s**2)/co else: return 2*c*s/co return rv elif not rv.args[0].is_Number: # make a change if the leading coefficient's numerator is # divisible by 2 c, m = rv.args[0].as_coeff_Mul(rational=True) if c.p % 2 == 0: arg = c.p//2*m/c.q c = TR11(cos(arg)) s = TR11(sin(arg)) if rv.func == sin: rv = 2*s*c else: rv = c**2 - s**2 return rv return bottom_up(rv, f) def TR12(rv, first=True): """Separate sums in ``tan``. Examples ======== >>> from sympy.simplify.fu import TR12 >>> from sympy.abc import x, y >>> from sympy import tan >>> from sympy.simplify.fu import TR12 >>> TR12(tan(x + y)) (tan(x) + tan(y))/(-tan(x)*tan(y) + 1) """ def f(rv): if not rv.func == tan: return rv arg = rv.args[0] if arg.is_Add: if first: args = list(ordered(arg.args)) else: args = list(arg.args) a = args.pop() b = Add._from_args(args) if b.is_Add: tb = TR12(tan(b), first=False) else: tb = tan(b) return (tan(a) + tb)/(1 - tan(a)*tb) return rv return bottom_up(rv, f) def TR12i(rv): """Combine tan arguments as (tan(y) + tan(x))/(tan(x)*tan(y) - 1) -> -tan(x + y) Examples ======== >>> from sympy.simplify.fu import TR12i >>> from sympy import tan >>> from sympy.abc import a, b, c >>> ta, tb, tc = [tan(i) for i in (a, b, c)] >>> TR12i((ta + tb)/(-ta*tb + 1)) tan(a + b) >>> TR12i((ta + tb)/(ta*tb - 1)) -tan(a + b) >>> TR12i((-ta - tb)/(ta*tb - 1)) tan(a + b) >>> eq = (ta + tb)/(-ta*tb + 1)**2*(-3*ta - 3*tc)/(2*(ta*tc - 1)) >>> TR12i(eq.expand()) -3*tan(a + b)*tan(a + c)/(2*(tan(a) + tan(b) - 1)) """ from sympy import factor def f(rv): if not (rv.is_Add or rv.is_Mul or rv.is_Pow): return rv n, d = rv.as_numer_denom() if not d.args or not n.args: return rv dok = {} def ok(di): m = as_f_sign_1(di) if m: g, f, s = m if s is S.NegativeOne and f.is_Mul and len(f.args) == 2 and \ all(isinstance(fi, tan) for fi in f.args): return g, f d_args = list(Mul.make_args(d)) for i, di in enumerate(d_args): m = ok(di) if m: g, t = m s = Add(*[_.args[0] for _ in t.args]) dok[s] = S.One d_args[i] = g continue if di.is_Add: di = factor(di) if di.is_Mul: d_args.extend(di.args) d_args[i] = S.One elif di.is_Pow and (di.exp.is_integer or di.base.is_positive): m = ok(di.base) if m: g, t = m s = Add(*[_.args[0] for _ in t.args]) dok[s] = di.exp d_args[i] = g**di.exp else: di = factor(di) if di.is_Mul: d_args.extend(di.args) d_args[i] = S.One if not dok: return rv def ok(ni): if ni.is_Add and len(ni.args) == 2: a, b = ni.args if isinstance(a, tan) and isinstance(b, tan): return a, b n_args = list(Mul.make_args(factor_terms(n))) hit = False for i, ni in enumerate(n_args): m = ok(ni) if not m: m = ok(-ni) if m: n_args[i] = S.NegativeOne else: if ni.is_Add: ni = factor(ni) if ni.is_Mul: n_args.extend(ni.args) n_args[i] = S.One continue elif ni.is_Pow and ( ni.exp.is_integer or ni.base.is_positive): m = ok(ni.base) if m: n_args[i] = S.One else: ni = factor(ni) if ni.is_Mul: n_args.extend(ni.args) n_args[i] = S.One continue else: continue else: n_args[i] = S.One hit = True s = Add(*[_.args[0] for _ in m]) ed = dok[s] newed = ed.extract_additively(S.One) if newed is not None: if newed: dok[s] = newed else: dok.pop(s) n_args[i] *= -tan(s) if hit: rv = Mul(*n_args)/Mul(*d_args)/Mul(*[(Add(*[ tan(a) for a in i.args]) - 1)**e for i, e in dok.items()]) return rv return bottom_up(rv, f) def TR13(rv): """Change products of ``tan`` or ``cot``. Examples ======== >>> from sympy.simplify.fu import TR13 >>> from sympy import tan, cot, cos >>> TR13(tan(3)*tan(2)) -tan(2)/tan(5) - tan(3)/tan(5) + 1 >>> TR13(cot(3)*cot(2)) cot(2)*cot(5) + 1 + cot(3)*cot(5) """ def f(rv): if not rv.is_Mul: return rv # XXX handle products of powers? or let power-reducing handle it? args = {tan: [], cot: [], None: []} for a in ordered(Mul.make_args(rv)): if a.func in (tan, cot): args[a.func].append(a.args[0]) else: args[None].append(a) t = args[tan] c = args[cot] if len(t) < 2 and len(c) < 2: return rv args = args[None] while len(t) > 1: t1 = t.pop() t2 = t.pop() args.append(1 - (tan(t1)/tan(t1 + t2) + tan(t2)/tan(t1 + t2))) if t: args.append(tan(t.pop())) while len(c) > 1: t1 = c.pop() t2 = c.pop() args.append(1 + cot(t1)*cot(t1 + t2) + cot(t2)*cot(t1 + t2)) if c: args.append(cot(c.pop())) return Mul(*args) return bottom_up(rv, f) def TRmorrie(rv): """Returns cos(x)*cos(2*x)*...*cos(2**(k-1)*x) -> sin(2**k*x)/(2**k*sin(x)) Examples ======== >>> from sympy.simplify.fu import TRmorrie, TR8, TR3 >>> from sympy.abc import x >>> from sympy import Mul, cos, pi >>> TRmorrie(cos(x)*cos(2*x)) sin(4*x)/(4*sin(x)) >>> TRmorrie(7*Mul(*[cos(x) for x in range(10)])) 7*sin(12)*sin(16)*cos(5)*cos(7)*cos(9)/(64*sin(1)*sin(3)) Sometimes autosimplification will cause a power to be not recognized. e.g. in the following, cos(4*pi/7) automatically simplifies to -cos(3*pi/7) so only 2 of the 3 terms are recognized: >>> TRmorrie(cos(pi/7)*cos(2*pi/7)*cos(4*pi/7)) -sin(3*pi/7)*cos(3*pi/7)/(4*sin(pi/7)) A touch by TR8 resolves the expression to a Rational >>> TR8(_) -1/8 In this case, if eq is unsimplified, the answer is obtained directly: >>> eq = cos(pi/9)*cos(2*pi/9)*cos(3*pi/9)*cos(4*pi/9) >>> TRmorrie(eq) 1/16 But if angles are made canonical with TR3 then the answer is not simplified without further work: >>> TR3(eq) sin(pi/18)*cos(pi/9)*cos(2*pi/9)/2 >>> TRmorrie(_) sin(pi/18)*sin(4*pi/9)/(8*sin(pi/9)) >>> TR8(_) cos(7*pi/18)/(16*sin(pi/9)) >>> TR3(_) 1/16 The original expression would have resolve to 1/16 directly with TR8, however: >>> TR8(eq) 1/16 References ========== https://en.wikipedia.org/wiki/Morrie%27s_law """ def f(rv): if not rv.is_Mul: return rv args = defaultdict(list) coss = {} other = [] for c in rv.args: b, e = c.as_base_exp() if e.is_Integer and isinstance(b, cos): co, a = b.args[0].as_coeff_Mul() args[a].append(co) coss[b] = e else: other.append(c) new = [] for a in args: c = args[a] c.sort() no = [] while c: k = 0 cc = ci = c[0] while cc in c: k += 1 cc *= 2 if k > 1: newarg = sin(2**k*ci*a)/2**k/sin(ci*a) # see how many times this can be taken take = None ccs = [] for i in range(k): cc /= 2 key = cos(a*cc, evaluate=False) ccs.append(cc) take = min(coss[key], take or coss[key]) # update exponent counts for i in range(k): cc = ccs.pop() key = cos(a*cc, evaluate=False) coss[key] -= take if not coss[key]: c.remove(cc) new.append(newarg**take) else: no.append(c.pop(0)) c[:] = no if new: rv = Mul(*(new + other + [ cos(k*a, evaluate=False) for a in args for k in args[a]])) return rv return bottom_up(rv, f) def TR14(rv, first=True): """Convert factored powers of sin and cos identities into simpler expressions. Examples ======== >>> from sympy.simplify.fu import TR14 >>> from sympy.abc import x, y >>> from sympy import cos, sin >>> TR14((cos(x) - 1)*(cos(x) + 1)) -sin(x)**2 >>> TR14((sin(x) - 1)*(sin(x) + 1)) -cos(x)**2 >>> p1 = (cos(x) + 1)*(cos(x) - 1) >>> p2 = (cos(y) - 1)*2*(cos(y) + 1) >>> p3 = (3*(cos(y) - 1))*(3*(cos(y) + 1)) >>> TR14(p1*p2*p3*(x - 1)) -18*(x - 1)*sin(x)**2*sin(y)**4 """ def f(rv): if not rv.is_Mul: return rv if first: # sort them by location in numerator and denominator # so the code below can just deal with positive exponents n, d = rv.as_numer_denom() if d is not S.One: newn = TR14(n, first=False) newd = TR14(d, first=False) if newn != n or newd != d: rv = newn/newd return rv other = [] process = [] for a in rv.args: if a.is_Pow: b, e = a.as_base_exp() if not (e.is_integer or b.is_positive): other.append(a) continue a = b else: e = S.One m = as_f_sign_1(a) if not m or m[1].func not in (cos, sin): if e is S.One: other.append(a) else: other.append(a**e) continue g, f, si = m process.append((g, e.is_Number, e, f, si, a)) # sort them to get like terms next to each other process = list(ordered(process)) # keep track of whether there was any change nother = len(other) # access keys keys = (g, t, e, f, si, a) = list(range(6)) while process: A = process.pop(0) if process: B = process[0] if A[e].is_Number and B[e].is_Number: # both exponents are numbers if A[f] == B[f]: if A[si] != B[si]: B = process.pop(0) take = min(A[e], B[e]) # reinsert any remainder # the B will likely sort after A so check it first if B[e] != take: rem = [B[i] for i in keys] rem[e] -= take process.insert(0, rem) elif A[e] != take: rem = [A[i] for i in keys] rem[e] -= take process.insert(0, rem) if isinstance(A[f], cos): t = sin else: t = cos other.append((-A[g]*B[g]*t(A[f].args[0])**2)**take) continue elif A[e] == B[e]: # both exponents are equal symbols if A[f] == B[f]: if A[si] != B[si]: B = process.pop(0) take = A[e] if isinstance(A[f], cos): t = sin else: t = cos other.append((-A[g]*B[g]*t(A[f].args[0])**2)**take) continue # either we are done or neither condition above applied other.append(A[a]**A[e]) if len(other) != nother: rv = Mul(*other) return rv return bottom_up(rv, f) def TR15(rv, max=4, pow=False): """Convert sin(x)*-2 to 1 + cot(x)**2. See _TR56 docstring for advanced use of ``max`` and ``pow``. Examples ======== >>> from sympy.simplify.fu import TR15 >>> from sympy.abc import x >>> from sympy import cos, sin >>> TR15(1 - 1/sin(x)**2) -cot(x)**2 """ def f(rv): if not (isinstance(rv, Pow) and isinstance(rv.base, sin)): return rv ia = 1/rv a = _TR56(ia, sin, cot, lambda x: 1 + x, max=max, pow=pow) if a != ia: rv = a return rv return bottom_up(rv, f) def TR16(rv, max=4, pow=False): """Convert cos(x)*-2 to 1 + tan(x)**2. See _TR56 docstring for advanced use of ``max`` and ``pow``. Examples ======== >>> from sympy.simplify.fu import TR16 >>> from sympy.abc import x >>> from sympy import cos, sin >>> TR16(1 - 1/cos(x)**2) -tan(x)**2 """ def f(rv): if not (isinstance(rv, Pow) and isinstance(rv.base, cos)): return rv ia = 1/rv a = _TR56(ia, cos, tan, lambda x: 1 + x, max=max, pow=pow) if a != ia: rv = a return rv return bottom_up(rv, f) def TR111(rv): """Convert f(x)**-i to g(x)**i where either ``i`` is an integer or the base is positive and f, g are: tan, cot; sin, csc; or cos, sec. Examples ======== >>> from sympy.simplify.fu import TR111 >>> from sympy.abc import x >>> from sympy import tan >>> TR111(1 - 1/tan(x)**2) -cot(x)**2 + 1 """ def f(rv): if not ( isinstance(rv, Pow) and (rv.base.is_positive or rv.exp.is_integer and rv.exp.is_negative)): return rv if isinstance(rv.base, tan): return cot(rv.base.args[0])**-rv.exp elif isinstance(rv.base, sin): return csc(rv.base.args[0])**-rv.exp elif isinstance(rv.base, cos): return sec(rv.base.args[0])**-rv.exp return rv return bottom_up(rv, f) def TR22(rv, max=4, pow=False): """Convert tan(x)**2 to sec(x)**2 - 1 and cot(x)**2 to csc(x)**2 - 1. See _TR56 docstring for advanced use of ``max`` and ``pow``. Examples ======== >>> from sympy.simplify.fu import TR22 >>> from sympy.abc import x >>> from sympy import tan, cot >>> TR22(1 + tan(x)**2) sec(x)**2 >>> TR22(1 + cot(x)**2) csc(x)**2 """ def f(rv): if not (isinstance(rv, Pow) and rv.base.func in (cot, tan)): return rv rv = _TR56(rv, tan, sec, lambda x: x - 1, max=max, pow=pow) rv = _TR56(rv, cot, csc, lambda x: x - 1, max=max, pow=pow) return rv return bottom_up(rv, f) def TRpower(rv): """Convert sin(x)**n and cos(x)**n with positive n to sums. Examples ======== >>> from sympy.simplify.fu import TRpower >>> from sympy.abc import x >>> from sympy import cos, sin >>> TRpower(sin(x)**6) -15*cos(2*x)/32 + 3*cos(4*x)/16 - cos(6*x)/32 + 5/16 >>> TRpower(sin(x)**3*cos(2*x)**4) (3*sin(x)/4 - sin(3*x)/4)*(cos(4*x)/2 + cos(8*x)/8 + 3/8) References ========== https://en.wikipedia.org/wiki/List_of_trigonometric_identities#Power-reduction_formulae """ def f(rv): if not (isinstance(rv, Pow) and isinstance(rv.base, (sin, cos))): return rv b, n = rv.as_base_exp() x = b.args[0] if n.is_Integer and n.is_positive: if n.is_odd and isinstance(b, cos): rv = 2**(1-n)*Add(*[binomial(n, k)*cos((n - 2*k)*x) for k in range((n + 1)/2)]) elif n.is_odd and isinstance(b, sin): rv = 2**(1-n)*(-1)**((n-1)/2)*Add(*[binomial(n, k)* (-1)**k*sin((n - 2*k)*x) for k in range((n + 1)/2)]) elif n.is_even and isinstance(b, cos): rv = 2**(1-n)*Add(*[binomial(n, k)*cos((n - 2*k)*x) for k in range(n/2)]) elif n.is_even and isinstance(b, sin): rv = 2**(1-n)*(-1)**(n/2)*Add(*[binomial(n, k)* (-1)**k*cos((n - 2*k)*x) for k in range(n/2)]) if n.is_even: rv += 2**(-n)*binomial(n, n/2) return rv return bottom_up(rv, f) def L(rv): """Return count of trigonometric functions in expression. Examples ======== >>> from sympy.simplify.fu import L >>> from sympy.abc import x >>> from sympy import cos, sin >>> L(cos(x)+sin(x)) 2 """ return S(rv.count(TrigonometricFunction)) # ============== end of basic Fu-like tools ===================== if SYMPY_DEBUG: (TR0, TR1, TR2, TR3, TR4, TR5, TR6, TR7, TR8, TR9, TR10, TR11, TR12, TR13, TR2i, TRmorrie, TR14, TR15, TR16, TR12i, TR111, TR22 )= list(map(debug, (TR0, TR1, TR2, TR3, TR4, TR5, TR6, TR7, TR8, TR9, TR10, TR11, TR12, TR13, TR2i, TRmorrie, TR14, TR15, TR16, TR12i, TR111, TR22))) # tuples are chains -- (f, g) -> lambda x: g(f(x)) # lists are choices -- [f, g] -> lambda x: min(f(x), g(x), key=objective) CTR1 = [(TR5, TR0), (TR6, TR0), identity] CTR2 = (TR11, [(TR5, TR0), (TR6, TR0), TR0]) CTR3 = [(TRmorrie, TR8, TR0), (TRmorrie, TR8, TR10i, TR0), identity] CTR4 = [(TR4, TR10i), identity] RL1 = (TR4, TR3, TR4, TR12, TR4, TR13, TR4, TR0) # XXX it's a little unclear how this one is to be implemented # see Fu paper of reference, page 7. What is the Union symbol referring to? # The diagram shows all these as one chain of transformations, but the # text refers to them being applied independently. Also, a break # if L starts to increase has not been implemented. RL2 = [ (TR4, TR3, TR10, TR4, TR3, TR11), (TR5, TR7, TR11, TR4), (CTR3, CTR1, TR9, CTR2, TR4, TR9, TR9, CTR4), identity, ] def fu(rv, measure=lambda x: (L(x), x.count_ops())): """Attempt to simplify expression by using transformation rules given in the algorithm by Fu et al. :func:`fu` will try to minimize the objective function ``measure``. By default this first minimizes the number of trig terms and then minimizes the number of total operations. Examples ======== >>> from sympy.simplify.fu import fu >>> from sympy import cos, sin, tan, pi, S, sqrt >>> from sympy.abc import x, y, a, b >>> fu(sin(50)**2 + cos(50)**2 + sin(pi/6)) 3/2 >>> fu(sqrt(6)*cos(x) + sqrt(2)*sin(x)) 2*sqrt(2)*sin(x + pi/3) CTR1 example >>> eq = sin(x)**4 - cos(y)**2 + sin(y)**2 + 2*cos(x)**2 >>> fu(eq) cos(x)**4 - 2*cos(y)**2 + 2 CTR2 example >>> fu(S.Half - cos(2*x)/2) sin(x)**2 CTR3 example >>> fu(sin(a)*(cos(b) - sin(b)) + cos(a)*(sin(b) + cos(b))) sqrt(2)*sin(a + b + pi/4) CTR4 example >>> fu(sqrt(3)*cos(x)/2 + sin(x)/2) sin(x + pi/3) Example 1 >>> fu(1-sin(2*x)**2/4-sin(y)**2-cos(x)**4) -cos(x)**2 + cos(y)**2 Example 2 >>> fu(cos(4*pi/9)) sin(pi/18) >>> fu(cos(pi/9)*cos(2*pi/9)*cos(3*pi/9)*cos(4*pi/9)) 1/16 Example 3 >>> fu(tan(7*pi/18)+tan(5*pi/18)-sqrt(3)*tan(5*pi/18)*tan(7*pi/18)) -sqrt(3) Objective function example >>> fu(sin(x)/cos(x)) # default objective function tan(x) >>> fu(sin(x)/cos(x), measure=lambda x: -x.count_ops()) # maximize op count sin(x)/cos(x) References ========== http://rfdz.ph-noe.ac.at/fileadmin/Mathematik_Uploads/ACDCA/ DESTIME2006/DES_contribs/Fu/simplification.pdf """ fRL1 = greedy(RL1, measure) fRL2 = greedy(RL2, measure) was = rv rv = sympify(rv) if not isinstance(rv, Expr): return rv.func(*[fu(a, measure=measure) for a in rv.args]) rv = TR1(rv) if rv.has(tan, cot): rv1 = fRL1(rv) if (measure(rv1) < measure(rv)): rv = rv1 if rv.has(tan, cot): rv = TR2(rv) if rv.has(sin, cos): rv1 = fRL2(rv) rv2 = TR8(TRmorrie(rv1)) rv = min([was, rv, rv1, rv2], key=measure) return min(TR2i(rv), rv, key=measure) def process_common_addends(rv, do, key2=None, key1=True): """Apply ``do`` to addends of ``rv`` that (if key1=True) share at least a common absolute value of their coefficient and the value of ``key2`` when applied to the argument. If ``key1`` is False ``key2`` must be supplied and will be the only key applied. """ # collect by absolute value of coefficient and key2 absc = defaultdict(list) if key1: for a in rv.args: c, a = a.as_coeff_Mul() if c < 0: c = -c a = -a # put the sign on `a` absc[(c, key2(a) if key2 else 1)].append(a) elif key2: for a in rv.args: absc[(S.One, key2(a))].append(a) else: raise ValueError('must have at least one key') args = [] hit = False for k in absc: v = absc[k] c, _ = k if len(v) > 1: e = Add(*v, evaluate=False) new = do(e) if new != e: e = new hit = True args.append(c*e) else: args.append(c*v[0]) if hit: rv = Add(*args) return rv fufuncs = ''' TR0 TR1 TR2 TR3 TR4 TR5 TR6 TR7 TR8 TR9 TR10 TR10i TR11 TR12 TR13 L TR2i TRmorrie TR12i TR14 TR15 TR16 TR111 TR22'''.split() FU = dict(list(zip(fufuncs, list(map(locals().get, fufuncs))))) def _roots(): global _ROOT2, _ROOT3, _invROOT3 _ROOT2, _ROOT3 = sqrt(2), sqrt(3) _invROOT3 = 1/_ROOT3 _ROOT2 = None def trig_split(a, b, two=False): """Return the gcd, s1, s2, a1, a2, bool where If two is False (default) then:: a + b = gcd*(s1*f(a1) + s2*f(a2)) where f = cos if bool else sin else: if bool, a + b was +/- cos(a1)*cos(a2) +/- sin(a1)*sin(a2) and equals n1*gcd*cos(a - b) if n1 == n2 else n1*gcd*cos(a + b) else a + b was +/- cos(a1)*sin(a2) +/- sin(a1)*cos(a2) and equals n1*gcd*sin(a + b) if n1 = n2 else n1*gcd*sin(b - a) Examples ======== >>> from sympy.simplify.fu import trig_split >>> from sympy.abc import x, y, z >>> from sympy import cos, sin, sqrt >>> trig_split(cos(x), cos(y)) (1, 1, 1, x, y, True) >>> trig_split(2*cos(x), -2*cos(y)) (2, 1, -1, x, y, True) >>> trig_split(cos(x)*sin(y), cos(y)*sin(y)) (sin(y), 1, 1, x, y, True) >>> trig_split(cos(x), -sqrt(3)*sin(x), two=True) (2, 1, -1, x, pi/6, False) >>> trig_split(cos(x), sin(x), two=True) (sqrt(2), 1, 1, x, pi/4, False) >>> trig_split(cos(x), -sin(x), two=True) (sqrt(2), 1, -1, x, pi/4, False) >>> trig_split(sqrt(2)*cos(x), -sqrt(6)*sin(x), two=True) (2*sqrt(2), 1, -1, x, pi/6, False) >>> trig_split(-sqrt(6)*cos(x), -sqrt(2)*sin(x), two=True) (-2*sqrt(2), 1, 1, x, pi/3, False) >>> trig_split(cos(x)/sqrt(6), sin(x)/sqrt(2), two=True) (sqrt(6)/3, 1, 1, x, pi/6, False) >>> trig_split(-sqrt(6)*cos(x)*sin(y), -sqrt(2)*sin(x)*sin(y), two=True) (-2*sqrt(2)*sin(y), 1, 1, x, pi/3, False) >>> trig_split(cos(x), sin(x)) >>> trig_split(cos(x), sin(z)) >>> trig_split(2*cos(x), -sin(x)) >>> trig_split(cos(x), -sqrt(3)*sin(x)) >>> trig_split(cos(x)*cos(y), sin(x)*sin(z)) >>> trig_split(cos(x)*cos(y), sin(x)*sin(y)) >>> trig_split(-sqrt(6)*cos(x), sqrt(2)*sin(x)*sin(y), two=True) """ global _ROOT2, _ROOT3, _invROOT3 if _ROOT2 is None: _roots() a, b = [Factors(i) for i in (a, b)] ua, ub = a.normal(b) gcd = a.gcd(b).as_expr() n1 = n2 = 1 if S.NegativeOne in ua.factors: ua = ua.quo(S.NegativeOne) n1 = -n1 elif S.NegativeOne in ub.factors: ub = ub.quo(S.NegativeOne) n2 = -n2 a, b = [i.as_expr() for i in (ua, ub)] def pow_cos_sin(a, two): """Return ``a`` as a tuple (r, c, s) such that ``a = (r or 1)*(c or 1)*(s or 1)``. Three arguments are returned (radical, c-factor, s-factor) as long as the conditions set by ``two`` are met; otherwise None is returned. If ``two`` is True there will be one or two non-None values in the tuple: c and s or c and r or s and r or s or c with c being a cosine function (if possible) else a sine, and s being a sine function (if possible) else oosine. If ``two`` is False then there will only be a c or s term in the tuple. ``two`` also require that either two cos and/or sin be present (with the condition that if the functions are the same the arguments are different or vice versa) or that a single cosine or a single sine be present with an optional radical. If the above conditions dictated by ``two`` are not met then None is returned. """ c = s = None co = S.One if a.is_Mul: co, a = a.as_coeff_Mul() if len(a.args) > 2 or not two: return None if a.is_Mul: args = list(a.args) else: args = [a] a = args.pop(0) if isinstance(a, cos): c = a elif isinstance(a, sin): s = a elif a.is_Pow and a.exp is S.Half: # autoeval doesn't allow -1/2 co *= a else: return None if args: b = args[0] if isinstance(b, cos): if c: s = b else: c = b elif isinstance(b, sin): if s: c = b else: s = b elif b.is_Pow and b.exp is S.Half: co *= b else: return None return co if co is not S.One else None, c, s elif isinstance(a, cos): c = a elif isinstance(a, sin): s = a if c is None and s is None: return co = co if co is not S.One else None return co, c, s # get the parts m = pow_cos_sin(a, two) if m is None: return coa, ca, sa = m m = pow_cos_sin(b, two) if m is None: return cob, cb, sb = m # check them if (not ca) and cb or ca and isinstance(ca, sin): coa, ca, sa, cob, cb, sb = cob, cb, sb, coa, ca, sa n1, n2 = n2, n1 if not two: # need cos(x) and cos(y) or sin(x) and sin(y) c = ca or sa s = cb or sb if not isinstance(c, s.func): return None return gcd, n1, n2, c.args[0], s.args[0], isinstance(c, cos) else: if not coa and not cob: if (ca and cb and sa and sb): if isinstance(ca, sa.func) is not isinstance(cb, sb.func): return args = {j.args for j in (ca, sa)} if not all(i.args in args for i in (cb, sb)): return return gcd, n1, n2, ca.args[0], sa.args[0], isinstance(ca, sa.func) if ca and sa or cb and sb or \ two and (ca is None and sa is None or cb is None and sb is None): return c = ca or sa s = cb or sb if c.args != s.args: return if not coa: coa = S.One if not cob: cob = S.One if coa is cob: gcd *= _ROOT2 return gcd, n1, n2, c.args[0], pi/4, False elif coa/cob == _ROOT3: gcd *= 2*cob return gcd, n1, n2, c.args[0], pi/3, False elif coa/cob == _invROOT3: gcd *= 2*coa return gcd, n1, n2, c.args[0], pi/6, False def as_f_sign_1(e): """If ``e`` is a sum that can be written as ``g*(a + s)`` where ``s`` is ``+/-1``, return ``g``, ``a``, and ``s`` where ``a`` does not have a leading negative coefficient. Examples ======== >>> from sympy.simplify.fu import as_f_sign_1 >>> from sympy.abc import x >>> as_f_sign_1(x + 1) (1, x, 1) >>> as_f_sign_1(x - 1) (1, x, -1) >>> as_f_sign_1(-x + 1) (-1, x, -1) >>> as_f_sign_1(-x - 1) (-1, x, 1) >>> as_f_sign_1(2*x + 2) (2, x, 1) """ if not e.is_Add or len(e.args) != 2: return # exact match a, b = e.args if a in (S.NegativeOne, S.One): g = S.One if b.is_Mul and b.args[0].is_Number and b.args[0] < 0: a, b = -a, -b g = -g return g, b, a # gcd match a, b = [Factors(i) for i in e.args] ua, ub = a.normal(b) gcd = a.gcd(b).as_expr() if S.NegativeOne in ua.factors: ua = ua.quo(S.NegativeOne) n1 = -1 n2 = 1 elif S.NegativeOne in ub.factors: ub = ub.quo(S.NegativeOne) n1 = 1 n2 = -1 else: n1 = n2 = 1 a, b = [i.as_expr() for i in (ua, ub)] if a is S.One: a, b = b, a n1, n2 = n2, n1 if n1 == -1: gcd = -gcd n2 = -n2 if b is S.One: return gcd, a, n2 def _osborne(e, d): """Replace all hyperbolic functions with trig functions using the Osborne rule. Notes ===== ``d`` is a dummy variable to prevent automatic evaluation of trigonometric/hyperbolic functions. References ========== https://en.wikipedia.org/wiki/Hyperbolic_function """ def f(rv): if not isinstance(rv, HyperbolicFunction): return rv a = rv.args[0] a = a*d if not a.is_Add else Add._from_args([i*d for i in a.args]) if isinstance(rv, sinh): return I*sin(a) elif isinstance(rv, cosh): return cos(a) elif isinstance(rv, tanh): return I*tan(a) elif isinstance(rv, coth): return cot(a)/I elif isinstance(rv, sech): return sec(a) elif isinstance(rv, csch): return csc(a)/I else: raise NotImplementedError('unhandled %s' % rv.func) return bottom_up(e, f) def _osbornei(e, d): """Replace all trig functions with hyperbolic functions using the Osborne rule. Notes ===== ``d`` is a dummy variable to prevent automatic evaluation of trigonometric/hyperbolic functions. References ========== https://en.wikipedia.org/wiki/Hyperbolic_function """ def f(rv): if not isinstance(rv, TrigonometricFunction): return rv const, x = rv.args[0].as_independent(d, as_Add=True) a = x.xreplace({d: S.One}) + const*I if isinstance(rv, sin): return sinh(a)/I elif isinstance(rv, cos): return cosh(a) elif isinstance(rv, tan): return tanh(a)/I elif isinstance(rv, cot): return coth(a)*I elif isinstance(rv, sec): return sech(a) elif isinstance(rv, csc): return csch(a)*I else: raise NotImplementedError('unhandled %s' % rv.func) return bottom_up(e, f) def hyper_as_trig(rv): """Return an expression containing hyperbolic functions in terms of trigonometric functions. Any trigonometric functions initially present are replaced with Dummy symbols and the function to undo the masking and the conversion back to hyperbolics is also returned. It should always be true that:: t, f = hyper_as_trig(expr) expr == f(t) Examples ======== >>> from sympy.simplify.fu import hyper_as_trig, fu >>> from sympy.abc import x >>> from sympy import cosh, sinh >>> eq = sinh(x)**2 + cosh(x)**2 >>> t, f = hyper_as_trig(eq) >>> f(fu(t)) cosh(2*x) References ========== https://en.wikipedia.org/wiki/Hyperbolic_function """ from sympy.simplify.simplify import signsimp from sympy.simplify.radsimp import collect # mask off trig functions trigs = rv.atoms(TrigonometricFunction) reps = [(t, Dummy()) for t in trigs] masked = rv.xreplace(dict(reps)) # get inversion substitutions in place reps = [(v, k) for k, v in reps] d = Dummy() return _osborne(masked, d), lambda x: collect(signsimp( _osbornei(x, d).xreplace(dict(reps))), S.ImaginaryUnit) def sincos_to_sum(expr): """Convert products and powers of sin and cos to sums. Applied power reduction TRpower first, then expands products, and converts products to sums with TR8. Examples ======== >>> from sympy.simplify.fu import sincos_to_sum >>> from sympy.abc import x >>> from sympy import cos, sin >>> sincos_to_sum(16*sin(x)**3*cos(2*x)**2) 7*sin(x) - 5*sin(3*x) + 3*sin(5*x) - sin(7*x) """ if not expr.has(cos, sin): return expr else: return TR8(expand_mul(TRpower(expr)))

8cf9903b7dd9c2411d5ccdd227670828e59b51dca7f208383ba67e198ea32366

""" This module cooks up a docstring when imported. Its only purpose is to be displayed in the sphinx documentation. """ from __future__ import print_function, division from sympy import latex, Eq, hyper from sympy.simplify.hyperexpand import FormulaCollection c = FormulaCollection() doc = "" for f in c.formulae: obj = Eq(hyper(f.func.ap, f.func.bq, f.z), f.closed_form.rewrite('nonrepsmall')) doc += ".. math::\n %s\n" % latex(obj) __doc__ = doc

977e80bdd1b09ed4c19fa01479b35b83a73a6af335cf471fe559b59ad83270aa

from __future__ import print_function, division from itertools import combinations_with_replacement from sympy.core import symbols, Add, Dummy from sympy.core.numbers import Rational from sympy.polys import cancel, ComputationFailed, parallel_poly_from_expr, reduced, Poly from sympy.polys.monomials import Monomial, monomial_div from sympy.polys.polyerrors import DomainError, PolificationFailed from sympy.utilities.misc import debug def ratsimp(expr): """ Put an expression over a common denominator, cancel and reduce. Examples ======== >>> from sympy import ratsimp >>> from sympy.abc import x, y >>> ratsimp(1/x + 1/y) (x + y)/(x*y) """ f, g = cancel(expr).as_numer_denom() try: Q, r = reduced(f, [g], field=True, expand=False) except ComputationFailed: return f/g return Add(*Q) + cancel(r/g) def ratsimpmodprime(expr, G, *gens, **args): """ Simplifies a rational expression ``expr`` modulo the prime ideal generated by ``G``. ``G`` should be a Groebner basis of the ideal. >>> from sympy.simplify.ratsimp import ratsimpmodprime >>> from sympy.abc import x, y >>> eq = (x + y**5 + y)/(x - y) >>> ratsimpmodprime(eq, [x*y**5 - x - y], x, y, order='lex') (x**2 + x*y + x + y)/(x**2 - x*y) If ``polynomial`` is False, the algorithm computes a rational simplification which minimizes the sum of the total degrees of the numerator and the denominator. If ``polynomial`` is True, this function just brings numerator and denominator into a canonical form. This is much faster, but has potentially worse results. References ========== .. [1] M. Monagan, R. Pearce, Rational Simplification Modulo a Polynomial Ideal, http://citeseer.ist.psu.edu/viewdoc/summary?doi=10.1.1.163.6984 (specifically, the second algorithm) """ from sympy import solve quick = args.pop('quick', True) polynomial = args.pop('polynomial', False) debug('ratsimpmodprime', expr) # usual preparation of polynomials: num, denom = cancel(expr).as_numer_denom() try: polys, opt = parallel_poly_from_expr([num, denom] + G, *gens, **args) except PolificationFailed: return expr domain = opt.domain if domain.has_assoc_Field: opt.domain = domain.get_field() else: raise DomainError( "can't compute rational simplification over %s" % domain) # compute only once leading_monomials = [g.LM(opt.order) for g in polys[2:]] tested = set() def staircase(n): """ Compute all monomials with degree less than ``n`` that are not divisible by any element of ``leading_monomials``. """ if n == 0: return [1] S = [] for mi in combinations_with_replacement(range(len(opt.gens)), n): m = [0]*len(opt.gens) for i in mi: m[i] += 1 if all([monomial_div(m, lmg) is None for lmg in leading_monomials]): S.append(m) return [Monomial(s).as_expr(*opt.gens) for s in S] + staircase(n - 1) def _ratsimpmodprime(a, b, allsol, N=0, D=0): r""" Computes a rational simplification of ``a/b`` which minimizes the sum of the total degrees of the numerator and the denominator. The algorithm proceeds by looking at ``a * d - b * c`` modulo the ideal generated by ``G`` for some ``c`` and ``d`` with degree less than ``a`` and ``b`` respectively. The coefficients of ``c`` and ``d`` are indeterminates and thus the coefficients of the normalform of ``a * d - b * c`` are linear polynomials in these indeterminates. If these linear polynomials, considered as system of equations, have a nontrivial solution, then `\frac{a}{b} \equiv \frac{c}{d}` modulo the ideal generated by ``G``. So, by construction, the degree of ``c`` and ``d`` is less than the degree of ``a`` and ``b``, so a simpler representation has been found. After a simpler representation has been found, the algorithm tries to reduce the degree of the numerator and denominator and returns the result afterwards. As an extension, if quick=False, we look at all possible degrees such that the total degree is less than *or equal to* the best current solution. We retain a list of all solutions of minimal degree, and try to find the best one at the end. """ c, d = a, b steps = 0 maxdeg = a.total_degree() + b.total_degree() if quick: bound = maxdeg - 1 else: bound = maxdeg while N + D <= bound: if (N, D) in tested: break tested.add((N, D)) M1 = staircase(N) M2 = staircase(D) debug('%s / %s: %s, %s' % (N, D, M1, M2)) Cs = symbols("c:%d" % len(M1), cls=Dummy) Ds = symbols("d:%d" % len(M2), cls=Dummy) ng = Cs + Ds c_hat = Poly( sum([Cs[i] * M1[i] for i in range(len(M1))]), opt.gens + ng) d_hat = Poly( sum([Ds[i] * M2[i] for i in range(len(M2))]), opt.gens + ng) r = reduced(a * d_hat - b * c_hat, G, opt.gens + ng, order=opt.order, polys=True)[1] S = Poly(r, gens=opt.gens).coeffs() sol = solve(S, Cs + Ds, particular=True, quick=True) if sol and not all([s == 0 for s in sol.values()]): c = c_hat.subs(sol) d = d_hat.subs(sol) # The "free" variables occurring before as parameters # might still be in the substituted c, d, so set them # to the value chosen before: c = c.subs(dict(list(zip(Cs + Ds, [1] * (len(Cs) + len(Ds)))))) d = d.subs(dict(list(zip(Cs + Ds, [1] * (len(Cs) + len(Ds)))))) c = Poly(c, opt.gens) d = Poly(d, opt.gens) if d == 0: raise ValueError('Ideal not prime?') allsol.append((c_hat, d_hat, S, Cs + Ds)) if N + D != maxdeg: allsol = [allsol[-1]] break steps += 1 N += 1 D += 1 if steps > 0: c, d, allsol = _ratsimpmodprime(c, d, allsol, N, D - steps) c, d, allsol = _ratsimpmodprime(c, d, allsol, N - steps, D) return c, d, allsol # preprocessing. this improves performance a bit when deg(num) # and deg(denom) are large: num = reduced(num, G, opt.gens, order=opt.order)[1] denom = reduced(denom, G, opt.gens, order=opt.order)[1] if polynomial: return (num/denom).cancel() c, d, allsol = _ratsimpmodprime( Poly(num, opt.gens, domain=opt.domain), Poly(denom, opt.gens, domain=opt.domain), []) if not quick and allsol: debug('Looking for best minimal solution. Got: %s' % len(allsol)) newsol = [] for c_hat, d_hat, S, ng in allsol: sol = solve(S, ng, particular=True, quick=False) newsol.append((c_hat.subs(sol), d_hat.subs(sol))) c, d = min(newsol, key=lambda x: len(x[0].terms()) + len(x[1].terms())) if not domain.is_Field: cn, c = c.clear_denoms(convert=True) dn, d = d.clear_denoms(convert=True) r = Rational(cn, dn) else: r = Rational(1) return (c*r.q)/(d*r.p)

7a8345040ea0ebbeb24b551356d303757f684ba87cdfabc7ce64fc81ad571c74

r""" This module contains :py:meth:`~sympy.solvers.ode.dsolve` and different helper functions that it uses. :py:meth:`~sympy.solvers.ode.dsolve` solves ordinary differential equations. See the docstring on the various functions for their uses. Note that partial differential equations support is in ``pde.py``. Note that hint functions have docstrings describing their various methods, but they are intended for internal use. Use ``dsolve(ode, func, hint=hint)`` to solve an ODE using a specific hint. See also the docstring on :py:meth:`~sympy.solvers.ode.dsolve`. **Functions in this module** These are the user functions in this module: - :py:meth:`~sympy.solvers.ode.dsolve` - Solves ODEs. - :py:meth:`~sympy.solvers.ode.classify_ode` - Classifies ODEs into possible hints for :py:meth:`~sympy.solvers.ode.dsolve`. - :py:meth:`~sympy.solvers.ode.checkodesol` - Checks if an equation is the solution to an ODE. - :py:meth:`~sympy.solvers.ode.homogeneous_order` - Returns the homogeneous order of an expression. - :py:meth:`~sympy.solvers.ode.infinitesimals` - Returns the infinitesimals of the Lie group of point transformations of an ODE, such that it is invariant. - :py:meth:`~sympy.solvers.ode_checkinfsol` - Checks if the given infinitesimals are the actual infinitesimals of a first order ODE. These are the non-solver helper functions that are for internal use. The user should use the various options to :py:meth:`~sympy.solvers.ode.dsolve` to obtain the functionality provided by these functions: - :py:meth:`~sympy.solvers.ode.odesimp` - Does all forms of ODE simplification. - :py:meth:`~sympy.solvers.ode.ode_sol_simplicity` - A key function for comparing solutions by simplicity. - :py:meth:`~sympy.solvers.ode.constantsimp` - Simplifies arbitrary constants. - :py:meth:`~sympy.solvers.ode.constant_renumber` - Renumber arbitrary constants. - :py:meth:`~sympy.solvers.ode._handle_Integral` - Evaluate unevaluated Integrals. See also the docstrings of these functions. **Currently implemented solver methods** The following methods are implemented for solving ordinary differential equations. See the docstrings of the various hint functions for more information on each (run ``help(ode)``): - 1st order separable differential equations. - 1st order differential equations whose coefficients or `dx` and `dy` are functions homogeneous of the same order. - 1st order exact differential equations. - 1st order linear differential equations. - 1st order Bernoulli differential equations. - Power series solutions for first order differential equations. - Lie Group method of solving first order differential equations. - 2nd order Liouville differential equations. - Power series solutions for second order differential equations at ordinary and regular singular points. - `n`\th order differential equation that can be solved with algebraic rearrangement and integration. - `n`\th order linear homogeneous differential equation with constant coefficients. - `n`\th order linear inhomogeneous differential equation with constant coefficients using the method of undetermined coefficients. - `n`\th order linear inhomogeneous differential equation with constant coefficients using the method of variation of parameters. **Philosophy behind this module** This module is designed to make it easy to add new ODE solving methods without having to mess with the solving code for other methods. The idea is that there is a :py:meth:`~sympy.solvers.ode.classify_ode` function, which takes in an ODE and tells you what hints, if any, will solve the ODE. It does this without attempting to solve the ODE, so it is fast. Each solving method is a hint, and it has its own function, named ``ode_<hint>``. That function takes in the ODE and any match expression gathered by :py:meth:`~sympy.solvers.ode.classify_ode` and returns a solved result. If this result has any integrals in it, the hint function will return an unevaluated :py:class:`~sympy.integrals.Integral` class. :py:meth:`~sympy.solvers.ode.dsolve`, which is the user wrapper function around all of this, will then call :py:meth:`~sympy.solvers.ode.odesimp` on the result, which, among other things, will attempt to solve the equation for the dependent variable (the function we are solving for), simplify the arbitrary constants in the expression, and evaluate any integrals, if the hint allows it. **How to add new solution methods** If you have an ODE that you want :py:meth:`~sympy.solvers.ode.dsolve` to be able to solve, try to avoid adding special case code here. Instead, try finding a general method that will solve your ODE, as well as others. This way, the :py:mod:`~sympy.solvers.ode` module will become more robust, and unhindered by special case hacks. WolphramAlpha and Maple's DETools[odeadvisor] function are two resources you can use to classify a specific ODE. It is also better for a method to work with an `n`\th order ODE instead of only with specific orders, if possible. To add a new method, there are a few things that you need to do. First, you need a hint name for your method. Try to name your hint so that it is unambiguous with all other methods, including ones that may not be implemented yet. If your method uses integrals, also include a ``hint_Integral`` hint. If there is more than one way to solve ODEs with your method, include a hint for each one, as well as a ``<hint>_best`` hint. Your ``ode_<hint>_best()`` function should choose the best using min with ``ode_sol_simplicity`` as the key argument. See :py:meth:`~sympy.solvers.ode.ode_1st_homogeneous_coeff_best`, for example. The function that uses your method will be called ``ode_<hint>()``, so the hint must only use characters that are allowed in a Python function name (alphanumeric characters and the underscore '``_``' character). Include a function for every hint, except for ``_Integral`` hints (:py:meth:`~sympy.solvers.ode.dsolve` takes care of those automatically). Hint names should be all lowercase, unless a word is commonly capitalized (such as Integral or Bernoulli). If you have a hint that you do not want to run with ``all_Integral`` that doesn't have an ``_Integral`` counterpart (such as a best hint that would defeat the purpose of ``all_Integral``), you will need to remove it manually in the :py:meth:`~sympy.solvers.ode.dsolve` code. See also the :py:meth:`~sympy.solvers.ode.classify_ode` docstring for guidelines on writing a hint name. Determine *in general* how the solutions returned by your method compare with other methods that can potentially solve the same ODEs. Then, put your hints in the :py:data:`~sympy.solvers.ode.allhints` tuple in the order that they should be called. The ordering of this tuple determines which hints are default. Note that exceptions are ok, because it is easy for the user to choose individual hints with :py:meth:`~sympy.solvers.ode.dsolve`. In general, ``_Integral`` variants should go at the end of the list, and ``_best`` variants should go before the various hints they apply to. For example, the ``undetermined_coefficients`` hint comes before the ``variation_of_parameters`` hint because, even though variation of parameters is more general than undetermined coefficients, undetermined coefficients generally returns cleaner results for the ODEs that it can solve than variation of parameters does, and it does not require integration, so it is much faster. Next, you need to have a match expression or a function that matches the type of the ODE, which you should put in :py:meth:`~sympy.solvers.ode.classify_ode` (if the match function is more than just a few lines, like :py:meth:`~sympy.solvers.ode._undetermined_coefficients_match`, it should go outside of :py:meth:`~sympy.solvers.ode.classify_ode`). It should match the ODE without solving for it as much as possible, so that :py:meth:`~sympy.solvers.ode.classify_ode` remains fast and is not hindered by bugs in solving code. Be sure to consider corner cases. For example, if your solution method involves dividing by something, make sure you exclude the case where that division will be 0. In most cases, the matching of the ODE will also give you the various parts that you need to solve it. You should put that in a dictionary (``.match()`` will do this for you), and add that as ``matching_hints['hint'] = matchdict`` in the relevant part of :py:meth:`~sympy.solvers.ode.classify_ode`. :py:meth:`~sympy.solvers.ode.classify_ode` will then send this to :py:meth:`~sympy.solvers.ode.dsolve`, which will send it to your function as the ``match`` argument. Your function should be named ``ode_<hint>(eq, func, order, match)`. If you need to send more information, put it in the ``match`` dictionary. For example, if you had to substitute in a dummy variable in :py:meth:`~sympy.solvers.ode.classify_ode` to match the ODE, you will need to pass it to your function using the `match` dict to access it. You can access the independent variable using ``func.args[0]``, and the dependent variable (the function you are trying to solve for) as ``func.func``. If, while trying to solve the ODE, you find that you cannot, raise ``NotImplementedError``. :py:meth:`~sympy.solvers.ode.dsolve` will catch this error with the ``all`` meta-hint, rather than causing the whole routine to fail. Add a docstring to your function that describes the method employed. Like with anything else in SymPy, you will need to add a doctest to the docstring, in addition to real tests in ``test_ode.py``. Try to maintain consistency with the other hint functions' docstrings. Add your method to the list at the top of this docstring. Also, add your method to ``ode.rst`` in the ``docs/src`` directory, so that the Sphinx docs will pull its docstring into the main SymPy documentation. Be sure to make the Sphinx documentation by running ``make html`` from within the doc directory to verify that the docstring formats correctly. If your solution method involves integrating, use :py:meth:`Integral() <sympy.integrals.integrals.Integral>` instead of :py:meth:`~sympy.core.expr.Expr.integrate`. This allows the user to bypass hard/slow integration by using the ``_Integral`` variant of your hint. In most cases, calling :py:meth:`sympy.core.basic.Basic.doit` will integrate your solution. If this is not the case, you will need to write special code in :py:meth:`~sympy.solvers.ode._handle_Integral`. Arbitrary constants should be symbols named ``C1``, ``C2``, and so on. All solution methods should return an equality instance. If you need an arbitrary number of arbitrary constants, you can use ``constants = numbered_symbols(prefix='C', cls=Symbol, start=1)``. If it is possible to solve for the dependent function in a general way, do so. Otherwise, do as best as you can, but do not call solve in your ``ode_<hint>()`` function. :py:meth:`~sympy.solvers.ode.odesimp` will attempt to solve the solution for you, so you do not need to do that. Lastly, if your ODE has a common simplification that can be applied to your solutions, you can add a special case in :py:meth:`~sympy.solvers.ode.odesimp` for it. For example, solutions returned from the ``1st_homogeneous_coeff`` hints often have many :py:meth:`~sympy.functions.log` terms, so :py:meth:`~sympy.solvers.ode.odesimp` calls :py:meth:`~sympy.simplify.simplify.logcombine` on them (it also helps to write the arbitrary constant as ``log(C1)`` instead of ``C1`` in this case). Also consider common ways that you can rearrange your solution to have :py:meth:`~sympy.solvers.ode.constantsimp` take better advantage of it. It is better to put simplification in :py:meth:`~sympy.solvers.ode.odesimp` than in your method, because it can then be turned off with the simplify flag in :py:meth:`~sympy.solvers.ode.dsolve`. If you have any extraneous simplification in your function, be sure to only run it using ``if match.get('simplify', True):``, especially if it can be slow or if it can reduce the domain of the solution. Finally, as with every contribution to SymPy, your method will need to be tested. Add a test for each method in ``test_ode.py``. Follow the conventions there, i.e., test the solver using ``dsolve(eq, f(x), hint=your_hint)``, and also test the solution using :py:meth:`~sympy.solvers.ode.checkodesol` (you can put these in a separate tests and skip/XFAIL if it runs too slow/doesn't work). Be sure to call your hint specifically in :py:meth:`~sympy.solvers.ode.dsolve`, that way the test won't be broken simply by the introduction of another matching hint. If your method works for higher order (>1) ODEs, you will need to run ``sol = constant_renumber(sol, 'C', 1, order)`` for each solution, where ``order`` is the order of the ODE. This is because ``constant_renumber`` renumbers the arbitrary constants by printing order, which is platform dependent. Try to test every corner case of your solver, including a range of orders if it is a `n`\th order solver, but if your solver is slow, such as if it involves hard integration, try to keep the test run time down. Feel free to refactor existing hints to avoid duplicating code or creating inconsistencies. If you can show that your method exactly duplicates an existing method, including in the simplicity and speed of obtaining the solutions, then you can remove the old, less general method. The existing code is tested extensively in ``test_ode.py``, so if anything is broken, one of those tests will surely fail. """ from __future__ import print_function, division from collections import defaultdict from itertools import islice from functools import cmp_to_key from sympy.core import Add, S, Mul, Pow, oo from sympy.core.compatibility import ordered, iterable, is_sequence, range from sympy.core.containers import Tuple from sympy.core.exprtools import factor_terms from sympy.core.expr import AtomicExpr, Expr from sympy.core.function import (Function, Derivative, AppliedUndef, diff, expand, expand_mul, Subs, _mexpand) from sympy.core.multidimensional import vectorize from sympy.core.numbers import NaN, zoo, I, Number from sympy.core.relational import Equality, Eq from sympy.core.symbol import Symbol, Wild, Dummy, symbols from sympy.core.sympify import sympify from sympy.logic.boolalg import (BooleanAtom, And, Or, Not, BooleanTrue, BooleanFalse) from sympy.functions import cos, exp, im, log, re, sin, tan, sqrt, \ atan2, conjugate, Piecewise from sympy.functions.combinatorial.factorials import factorial from sympy.integrals.integrals import Integral, integrate from sympy.matrices import wronskian, Matrix, eye, zeros from sympy.polys import (Poly, RootOf, rootof, terms_gcd, PolynomialError, lcm, roots) from sympy.polys.polyroots import roots_quartic from sympy.polys.polytools import cancel, degree, div from sympy.series import Order from sympy.series.series import series from sympy.simplify import collect, logcombine, powsimp, separatevars, \ simplify, trigsimp, denom, posify, cse from sympy.simplify.powsimp import powdenest from sympy.simplify.radsimp import collect_const from sympy.solvers import solve from sympy.solvers.pde import pdsolve from sympy.utilities import numbered_symbols, default_sort_key, sift from sympy.solvers.deutils import _preprocess, ode_order, _desolve #: This is a list of hints in the order that they should be preferred by #: :py:meth:`~sympy.solvers.ode.classify_ode`. In general, hints earlier in the #: list should produce simpler solutions than those later in the list (for #: ODEs that fit both). For now, the order of this list is based on empirical #: observations by the developers of SymPy. #: #: The hint used by :py:meth:`~sympy.solvers.ode.dsolve` for a specific ODE #: can be overridden (see the docstring). #: #: In general, ``_Integral`` hints are grouped at the end of the list, unless #: there is a method that returns an unevaluable integral most of the time #: (which go near the end of the list anyway). ``default``, ``all``, #: ``best``, and ``all_Integral`` meta-hints should not be included in this #: list, but ``_best`` and ``_Integral`` hints should be included. allhints = ( "nth_algebraic", "separable", "1st_exact", "1st_linear", "Bernoulli", "Riccati_special_minus2", "1st_homogeneous_coeff_best", "1st_homogeneous_coeff_subs_indep_div_dep", "1st_homogeneous_coeff_subs_dep_div_indep", "almost_linear", "linear_coefficients", "separable_reduced", "1st_power_series", "lie_group", "nth_linear_constant_coeff_homogeneous", "nth_linear_euler_eq_homogeneous", "nth_linear_constant_coeff_undetermined_coefficients", "nth_linear_euler_eq_nonhomogeneous_undetermined_coefficients", "nth_linear_constant_coeff_variation_of_parameters", "nth_linear_euler_eq_nonhomogeneous_variation_of_parameters", "Liouville", "2nd_power_series_ordinary", "2nd_power_series_regular", "nth_algebraic_Integral", "separable_Integral", "1st_exact_Integral", "1st_linear_Integral", "Bernoulli_Integral", "1st_homogeneous_coeff_subs_indep_div_dep_Integral", "1st_homogeneous_coeff_subs_dep_div_indep_Integral", "almost_linear_Integral", "linear_coefficients_Integral", "separable_reduced_Integral", "nth_linear_constant_coeff_variation_of_parameters_Integral", "nth_linear_euler_eq_nonhomogeneous_variation_of_parameters_Integral", "Liouville_Integral", ) lie_heuristics = ( "abaco1_simple", "abaco1_product", "abaco2_similar", "abaco2_unique_unknown", "abaco2_unique_general", "linear", "function_sum", "bivariate", "chi" ) def sub_func_doit(eq, func, new): r""" When replacing the func with something else, we usually want the derivative evaluated, so this function helps in making that happen. To keep subs from having to look through all derivatives, we mask them off with dummy variables, do the func sub, and then replace masked-off derivatives with their doit values. Examples ======== >>> from sympy import Derivative, symbols, Function >>> from sympy.solvers.ode import sub_func_doit >>> x, z = symbols('x, z') >>> y = Function('y') >>> sub_func_doit(3*Derivative(y(x), x) - 1, y(x), x) 2 >>> sub_func_doit(x*Derivative(y(x), x) - y(x)**2 + y(x), y(x), ... 1/(x*(z + 1/x))) x*(-1/(x**2*(z + 1/x)) + 1/(x**3*(z + 1/x)**2)) + 1/(x*(z + 1/x)) ...- 1/(x**2*(z + 1/x)**2) """ reps = {} repu = {} for d in eq.atoms(Derivative): u = Dummy('u') repu[u] = d.subs(func, new).doit() reps[d] = u # Make sure that expressions such as ``Derivative(f(x), (x, 2))`` get # replaced before ``Derivative(f(x), x)``: # # Also replace e.g. Derivative(x*Derivative(f(x), x), x) before # Derivative(f(x), x) def cmp(subs1, subs2): return subs2[0].has(subs1[0]) - subs1[0].has(subs2[0]) key = lambda x: (-x[0].derivative_count, cmp_to_key(cmp)(x)) reps = sorted(reps.items(), key=key) return eq.subs(reps).subs(func, new).subs(repu) def get_numbered_constants(eq, num=1, start=1, prefix='C'): """ Returns a list of constants that do not occur in eq already. """ if isinstance(eq, Expr): eq = [eq] elif not iterable(eq): raise ValueError("Expected Expr or iterable but got %s" % eq) atom_set = set().union(*[i.free_symbols for i in eq]) func_set = set().union(*[i.atoms(Function) for i in eq]) if func_set: atom_set |= {Symbol(str(f.func)) for f in func_set} ncs = numbered_symbols(start=start, prefix=prefix, exclude=atom_set) Cs = [next(ncs) for i in range(num)] return (Cs[0] if num == 1 else tuple(Cs)) def dsolve(eq, func=None, hint="default", simplify=True, ics= None, xi=None, eta=None, x0=0, n=6, **kwargs): r""" Solves any (supported) kind of ordinary differential equation and system of ordinary differential equations. For single ordinary differential equation ========================================= It is classified under this when number of equation in ``eq`` is one. **Usage** ``dsolve(eq, f(x), hint)`` -> Solve ordinary differential equation ``eq`` for function ``f(x)``, using method ``hint``. **Details** ``eq`` can be any supported ordinary differential equation (see the :py:mod:`~sympy.solvers.ode` docstring for supported methods). This can either be an :py:class:`~sympy.core.relational.Equality`, or an expression, which is assumed to be equal to ``0``. ``f(x)`` is a function of one variable whose derivatives in that variable make up the ordinary differential equation ``eq``. In many cases it is not necessary to provide this; it will be autodetected (and an error raised if it couldn't be detected). ``hint`` is the solving method that you want dsolve to use. Use ``classify_ode(eq, f(x))`` to get all of the possible hints for an ODE. The default hint, ``default``, will use whatever hint is returned first by :py:meth:`~sympy.solvers.ode.classify_ode`. See Hints below for more options that you can use for hint. ``simplify`` enables simplification by :py:meth:`~sympy.solvers.ode.odesimp`. See its docstring for more information. Turn this off, for example, to disable solving of solutions for ``func`` or simplification of arbitrary constants. It will still integrate with this hint. Note that the solution may contain more arbitrary constants than the order of the ODE with this option enabled. ``xi`` and ``eta`` are the infinitesimal functions of an ordinary differential equation. They are the infinitesimals of the Lie group of point transformations for which the differential equation is invariant. The user can specify values for the infinitesimals. If nothing is specified, ``xi`` and ``eta`` are calculated using :py:meth:`~sympy.solvers.ode.infinitesimals` with the help of various heuristics. ``ics`` is the set of initial/boundary conditions for the differential equation. It should be given in the form of ``{f(x0): x1, f(x).diff(x).subs(x, x2): x3}`` and so on. For power series solutions, if no initial conditions are specified ``f(0)`` is assumed to be ``C0`` and the power series solution is calculated about 0. ``x0`` is the point about which the power series solution of a differential equation is to be evaluated. ``n`` gives the exponent of the dependent variable up to which the power series solution of a differential equation is to be evaluated. **Hints** Aside from the various solving methods, there are also some meta-hints that you can pass to :py:meth:`~sympy.solvers.ode.dsolve`: ``default``: This uses whatever hint is returned first by :py:meth:`~sympy.solvers.ode.classify_ode`. This is the default argument to :py:meth:`~sympy.solvers.ode.dsolve`. ``all``: To make :py:meth:`~sympy.solvers.ode.dsolve` apply all relevant classification hints, use ``dsolve(ODE, func, hint="all")``. This will return a dictionary of ``hint:solution`` terms. If a hint causes dsolve to raise the ``NotImplementedError``, value of that hint's key will be the exception object raised. The dictionary will also include some special keys: - ``order``: The order of the ODE. See also :py:meth:`~sympy.solvers.deutils.ode_order` in ``deutils.py``. - ``best``: The simplest hint; what would be returned by ``best`` below. - ``best_hint``: The hint that would produce the solution given by ``best``. If more than one hint produces the best solution, the first one in the tuple returned by :py:meth:`~sympy.solvers.ode.classify_ode` is chosen. - ``default``: The solution that would be returned by default. This is the one produced by the hint that appears first in the tuple returned by :py:meth:`~sympy.solvers.ode.classify_ode`. ``all_Integral``: This is the same as ``all``, except if a hint also has a corresponding ``_Integral`` hint, it only returns the ``_Integral`` hint. This is useful if ``all`` causes :py:meth:`~sympy.solvers.ode.dsolve` to hang because of a difficult or impossible integral. This meta-hint will also be much faster than ``all``, because :py:meth:`~sympy.core.expr.Expr.integrate` is an expensive routine. ``best``: To have :py:meth:`~sympy.solvers.ode.dsolve` try all methods and return the simplest one. This takes into account whether the solution is solvable in the function, whether it contains any Integral classes (i.e. unevaluatable integrals), and which one is the shortest in size. See also the :py:meth:`~sympy.solvers.ode.classify_ode` docstring for more info on hints, and the :py:mod:`~sympy.solvers.ode` docstring for a list of all supported hints. **Tips** - You can declare the derivative of an unknown function this way: >>> from sympy import Function, Derivative >>> from sympy.abc import x # x is the independent variable >>> f = Function("f")(x) # f is a function of x >>> # f_ will be the derivative of f with respect to x >>> f_ = Derivative(f, x) - See ``test_ode.py`` for many tests, which serves also as a set of examples for how to use :py:meth:`~sympy.solvers.ode.dsolve`. - :py:meth:`~sympy.solvers.ode.dsolve` always returns an :py:class:`~sympy.core.relational.Equality` class (except for the case when the hint is ``all`` or ``all_Integral``). If possible, it solves the solution explicitly for the function being solved for. Otherwise, it returns an implicit solution. - Arbitrary constants are symbols named ``C1``, ``C2``, and so on. - Because all solutions should be mathematically equivalent, some hints may return the exact same result for an ODE. Often, though, two different hints will return the same solution formatted differently. The two should be equivalent. Also note that sometimes the values of the arbitrary constants in two different solutions may not be the same, because one constant may have "absorbed" other constants into it. - Do ``help(ode.ode_<hintname>)`` to get help more information on a specific hint, where ``<hintname>`` is the name of a hint without ``_Integral``. For system of ordinary differential equations ============================================= **Usage** ``dsolve(eq, func)`` -> Solve a system of ordinary differential equations ``eq`` for ``func`` being list of functions including `x(t)`, `y(t)`, `z(t)` where number of functions in the list depends upon the number of equations provided in ``eq``. **Details** ``eq`` can be any supported system of ordinary differential equations This can either be an :py:class:`~sympy.core.relational.Equality`, or an expression, which is assumed to be equal to ``0``. ``func`` holds ``x(t)`` and ``y(t)`` being functions of one variable which together with some of their derivatives make up the system of ordinary differential equation ``eq``. It is not necessary to provide this; it will be autodetected (and an error raised if it couldn't be detected). **Hints** The hints are formed by parameters returned by classify_sysode, combining them give hints name used later for forming method name. Examples ======== >>> from sympy import Function, dsolve, Eq, Derivative, sin, cos, symbols >>> from sympy.abc import x >>> f = Function('f') >>> dsolve(Derivative(f(x), x, x) + 9*f(x), f(x)) Eq(f(x), C1*sin(3*x) + C2*cos(3*x)) >>> eq = sin(x)*cos(f(x)) + cos(x)*sin(f(x))*f(x).diff(x) >>> dsolve(eq, hint='1st_exact') [Eq(f(x), -acos(C1/cos(x)) + 2*pi), Eq(f(x), acos(C1/cos(x)))] >>> dsolve(eq, hint='almost_linear') [Eq(f(x), -acos(C1/cos(x)) + 2*pi), Eq(f(x), acos(C1/cos(x)))] >>> t = symbols('t') >>> x, y = symbols('x, y', cls=Function) >>> eq = (Eq(Derivative(x(t),t), 12*t*x(t) + 8*y(t)), Eq(Derivative(y(t),t), 21*x(t) + 7*t*y(t))) >>> dsolve(eq) [Eq(x(t), C1*x0(t) + C2*x0(t)*Integral(8*exp(Integral(7*t, t))*exp(Integral(12*t, t))/x0(t)**2, t)), Eq(y(t), C1*y0(t) + C2*(y0(t)*Integral(8*exp(Integral(7*t, t))*exp(Integral(12*t, t))/x0(t)**2, t) + exp(Integral(7*t, t))*exp(Integral(12*t, t))/x0(t)))] >>> eq = (Eq(Derivative(x(t),t),x(t)*y(t)*sin(t)), Eq(Derivative(y(t),t),y(t)**2*sin(t))) >>> dsolve(eq) {Eq(x(t), -exp(C1)/(C2*exp(C1) - cos(t))), Eq(y(t), -1/(C1 - cos(t)))} """ if iterable(eq): match = classify_sysode(eq, func) eq = match['eq'] order = match['order'] func = match['func'] t = list(list(eq[0].atoms(Derivative))[0].atoms(Symbol))[0] # keep highest order term coefficient positive for i in range(len(eq)): for func_ in func: if isinstance(func_, list): pass else: if eq[i].coeff(diff(func[i],t,ode_order(eq[i], func[i]))).is_negative: eq[i] = -eq[i] match['eq'] = eq if len(set(order.values()))!=1: raise ValueError("It solves only those systems of equations whose orders are equal") match['order'] = list(order.values())[0] def recur_len(l): return sum(recur_len(item) if isinstance(item,list) else 1 for item in l) if recur_len(func) != len(eq): raise ValueError("dsolve() and classify_sysode() work with " "number of functions being equal to number of equations") if match['type_of_equation'] is None: raise NotImplementedError else: if match['is_linear'] == True: if match['no_of_equation'] > 3: solvefunc = globals()['sysode_linear_neq_order%(order)s' % match] else: solvefunc = globals()['sysode_linear_%(no_of_equation)seq_order%(order)s' % match] else: solvefunc = globals()['sysode_nonlinear_%(no_of_equation)seq_order%(order)s' % match] sols = solvefunc(match) if ics: constants = Tuple(*sols).free_symbols - Tuple(*eq).free_symbols solved_constants = solve_ics(sols, func, constants, ics) return [sol.subs(solved_constants) for sol in sols] return sols else: given_hint = hint # hint given by the user # See the docstring of _desolve for more details. hints = _desolve(eq, func=func, hint=hint, simplify=True, xi=xi, eta=eta, type='ode', ics=ics, x0=x0, n=n, **kwargs) eq = hints.pop('eq', eq) all_ = hints.pop('all', False) if all_: retdict = {} failed_hints = {} gethints = classify_ode(eq, dict=True) orderedhints = gethints['ordered_hints'] for hint in hints: try: rv = _helper_simplify(eq, hint, hints[hint], simplify) except NotImplementedError as detail: failed_hints[hint] = detail else: retdict[hint] = rv func = hints[hint]['func'] retdict['best'] = min(list(retdict.values()), key=lambda x: ode_sol_simplicity(x, func, trysolving=not simplify)) if given_hint == 'best': return retdict['best'] for i in orderedhints: if retdict['best'] == retdict.get(i, None): retdict['best_hint'] = i break retdict['default'] = gethints['default'] retdict['order'] = gethints['order'] retdict.update(failed_hints) return retdict else: # The key 'hint' stores the hint needed to be solved for. hint = hints['hint'] return _helper_simplify(eq, hint, hints, simplify, ics=ics) def _helper_simplify(eq, hint, match, simplify=True, ics=None, **kwargs): r""" Helper function of dsolve that calls the respective :py:mod:`~sympy.solvers.ode` functions to solve for the ordinary differential equations. This minimizes the computation in calling :py:meth:`~sympy.solvers.deutils._desolve` multiple times. """ r = match if hint.endswith('_Integral'): solvefunc = globals()['ode_' + hint[:-len('_Integral')]] else: solvefunc = globals()['ode_' + hint] func = r['func'] order = r['order'] match = r[hint] free = eq.free_symbols cons = lambda s: s.free_symbols.difference(free) if simplify: # odesimp() will attempt to integrate, if necessary, apply constantsimp(), # attempt to solve for func, and apply any other hint specific # simplifications sols = solvefunc(eq, func, order, match) if isinstance(sols, Expr): rv = odesimp(sols, func, order, cons(sols), hint) else: rv = [odesimp(s, func, order, cons(s), hint) for s in sols] else: # We still want to integrate (you can disable it separately with the hint) match['simplify'] = False # Some hints can take advantage of this option rv = _handle_Integral(solvefunc(eq, func, order, match), func, order, hint) if ics and not 'power_series' in hint: if isinstance(rv, Expr): solved_constants = solve_ics([rv], [r['func']], cons(rv), ics) rv = rv.subs(solved_constants) else: rv1 = [] for s in rv: solved_constants = solve_ics([s], [r['func']], cons(s), ics) rv1.append(s.subs(solved_constants)) rv = rv1 return rv def solve_ics(sols, funcs, constants, ics): """ Solve for the constants given initial conditions ``sols`` is a list of solutions. ``funcs`` is a list of functions. ``constants`` is a list of constants. ``ics`` is the set of initial/boundary conditions for the differential equation. It should be given in the form of ``{f(x0): x1, f(x).diff(x).subs(x, x2): x3}`` and so on. Returns a dictionary mapping constants to values. ``solution.subs(constants)`` will replace the constants in ``solution``. Example ======= >>> # From dsolve(f(x).diff(x) - f(x), f(x)) >>> from sympy import symbols, Eq, exp, Function >>> from sympy.solvers.ode import solve_ics >>> f = Function('f') >>> x, C1 = symbols('x C1') >>> sols = [Eq(f(x), C1*exp(x))] >>> funcs = [f(x)] >>> constants = [C1] >>> ics = {f(0): 2} >>> solved_constants = solve_ics(sols, funcs, constants, ics) >>> solved_constants {C1: 2} >>> sols[0].subs(solved_constants) Eq(f(x), 2*exp(x)) """ # Assume ics are of the form f(x0): value or Subs(diff(f(x), x, n), (x, # x0)): value (currently checked by classify_ode). To solve, replace x # with x0, f(x0) with value, then solve for constants. For f^(n)(x0), # differentiate the solution n times, so that f^(n)(x) appears. x = funcs[0].args[0] diff_sols = [] subs_sols = [] diff_variables = set() for funcarg, value in ics.items(): if isinstance(funcarg, AppliedUndef): x0 = funcarg.args[0] matching_func = [f for f in funcs if f.func == funcarg.func][0] S = sols elif isinstance(funcarg, (Subs, Derivative)): if isinstance(funcarg, Subs): # Make sure it stays a subs. Otherwise subs below will produce # a different looking term. funcarg = funcarg.doit() if isinstance(funcarg, Subs): deriv = funcarg.expr x0 = funcarg.point[0] variables = funcarg.expr.variables matching_func = deriv elif isinstance(funcarg, Derivative): deriv = funcarg x0 = funcarg.variables[0] variables = (x,)*len(funcarg.variables) matching_func = deriv.subs(x0, x) if variables not in diff_variables: for sol in sols: if sol.has(deriv.expr.func): diff_sols.append(Eq(sol.lhs.diff(*variables), sol.rhs.diff(*variables))) diff_variables.add(variables) S = diff_sols else: raise NotImplementedError("Unrecognized initial condition") for sol in S: if sol.has(matching_func): sol2 = sol sol2 = sol2.subs(x, x0) sol2 = sol2.subs(funcarg, value) subs_sols.append(sol2) # TODO: Use solveset here try: solved_constants = solve(subs_sols, constants, dict=True) except NotImplementedError: solved_constants = [] # XXX: We can't differentiate between the solution not existing because of # invalid initial conditions, and not existing because solve is not smart # enough. If we could use solveset, this might be improvable, but for now, # we use NotImplementedError in this case. if not solved_constants: raise NotImplementedError("Couldn't solve for initial conditions") if solved_constants == True: raise ValueError("Initial conditions did not produce any solutions for constants. Perhaps they are degenerate.") if len(solved_constants) > 1: raise NotImplementedError("Initial conditions produced too many solutions for constants") if len(solved_constants[0]) != len(constants): raise ValueError("Initial conditions did not produce a solution for all constants. Perhaps they are under-specified.") return solved_constants[0] def classify_ode(eq, func=None, dict=False, ics=None, **kwargs): r""" Returns a tuple of possible :py:meth:`~sympy.solvers.ode.dsolve` classifications for an ODE. The tuple is ordered so that first item is the classification that :py:meth:`~sympy.solvers.ode.dsolve` uses to solve the ODE by default. In general, classifications at the near the beginning of the list will produce better solutions faster than those near the end, thought there are always exceptions. To make :py:meth:`~sympy.solvers.ode.dsolve` use a different classification, use ``dsolve(ODE, func, hint=<classification>)``. See also the :py:meth:`~sympy.solvers.ode.dsolve` docstring for different meta-hints you can use. If ``dict`` is true, :py:meth:`~sympy.solvers.ode.classify_ode` will return a dictionary of ``hint:match`` expression terms. This is intended for internal use by :py:meth:`~sympy.solvers.ode.dsolve`. Note that because dictionaries are ordered arbitrarily, this will most likely not be in the same order as the tuple. You can get help on different hints by executing ``help(ode.ode_hintname)``, where ``hintname`` is the name of the hint without ``_Integral``. See :py:data:`~sympy.solvers.ode.allhints` or the :py:mod:`~sympy.solvers.ode` docstring for a list of all supported hints that can be returned from :py:meth:`~sympy.solvers.ode.classify_ode`. Notes ===== These are remarks on hint names. ``_Integral`` If a classification has ``_Integral`` at the end, it will return the expression with an unevaluated :py:class:`~sympy.integrals.Integral` class in it. Note that a hint may do this anyway if :py:meth:`~sympy.core.expr.Expr.integrate` cannot do the integral, though just using an ``_Integral`` will do so much faster. Indeed, an ``_Integral`` hint will always be faster than its corresponding hint without ``_Integral`` because :py:meth:`~sympy.core.expr.Expr.integrate` is an expensive routine. If :py:meth:`~sympy.solvers.ode.dsolve` hangs, it is probably because :py:meth:`~sympy.core.expr.Expr.integrate` is hanging on a tough or impossible integral. Try using an ``_Integral`` hint or ``all_Integral`` to get it return something. Note that some hints do not have ``_Integral`` counterparts. This is because :py:meth:`~sympy.solvers.ode.integrate` is not used in solving the ODE for those method. For example, `n`\th order linear homogeneous ODEs with constant coefficients do not require integration to solve, so there is no ``nth_linear_homogeneous_constant_coeff_Integrate`` hint. You can easily evaluate any unevaluated :py:class:`~sympy.integrals.Integral`\s in an expression by doing ``expr.doit()``. Ordinals Some hints contain an ordinal such as ``1st_linear``. This is to help differentiate them from other hints, as well as from other methods that may not be implemented yet. If a hint has ``nth`` in it, such as the ``nth_linear`` hints, this means that the method used to applies to ODEs of any order. ``indep`` and ``dep`` Some hints contain the words ``indep`` or ``dep``. These reference the independent variable and the dependent function, respectively. For example, if an ODE is in terms of `f(x)`, then ``indep`` will refer to `x` and ``dep`` will refer to `f`. ``subs`` If a hints has the word ``subs`` in it, it means the the ODE is solved by substituting the expression given after the word ``subs`` for a single dummy variable. This is usually in terms of ``indep`` and ``dep`` as above. The substituted expression will be written only in characters allowed for names of Python objects, meaning operators will be spelled out. For example, ``indep``/``dep`` will be written as ``indep_div_dep``. ``coeff`` The word ``coeff`` in a hint refers to the coefficients of something in the ODE, usually of the derivative terms. See the docstring for the individual methods for more info (``help(ode)``). This is contrast to ``coefficients``, as in ``undetermined_coefficients``, which refers to the common name of a method. ``_best`` Methods that have more than one fundamental way to solve will have a hint for each sub-method and a ``_best`` meta-classification. This will evaluate all hints and return the best, using the same considerations as the normal ``best`` meta-hint. Examples ======== >>> from sympy import Function, classify_ode, Eq >>> from sympy.abc import x >>> f = Function('f') >>> classify_ode(Eq(f(x).diff(x), 0), f(x)) ('nth_algebraic', 'separable', '1st_linear', '1st_homogeneous_coeff_best', '1st_homogeneous_coeff_subs_indep_div_dep', '1st_homogeneous_coeff_subs_dep_div_indep', '1st_power_series', 'lie_group', 'nth_linear_constant_coeff_homogeneous', 'nth_linear_euler_eq_homogeneous', 'nth_algebraic_Integral', 'separable_Integral', '1st_linear_Integral', '1st_homogeneous_coeff_subs_indep_div_dep_Integral', '1st_homogeneous_coeff_subs_dep_div_indep_Integral') >>> classify_ode(f(x).diff(x, 2) + 3*f(x).diff(x) + 2*f(x) - 4) ('nth_linear_constant_coeff_undetermined_coefficients', 'nth_linear_constant_coeff_variation_of_parameters', 'nth_linear_constant_coeff_variation_of_parameters_Integral') """ ics = sympify(ics) prep = kwargs.pop('prep', True) if func and len(func.args) != 1: raise ValueError("dsolve() and classify_ode() only " "work with functions of one variable, not %s" % func) if prep or func is None: eq, func_ = _preprocess(eq, func) if func is None: func = func_ x = func.args[0] f = func.func y = Dummy('y') xi = kwargs.get('xi') eta = kwargs.get('eta') terms = kwargs.get('n') if isinstance(eq, Equality): if eq.rhs != 0: return classify_ode(eq.lhs - eq.rhs, func, dict=dict, ics=ics, xi=xi, n=terms, eta=eta, prep=False) eq = eq.lhs order = ode_order(eq, f(x)) # hint:matchdict or hint:(tuple of matchdicts) # Also will contain "default":<default hint> and "order":order items. matching_hints = {"order": order} if not order: if dict: matching_hints["default"] = None return matching_hints else: return () df = f(x).diff(x) a = Wild('a', exclude=[f(x)]) b = Wild('b', exclude=[f(x)]) c = Wild('c', exclude=[f(x)]) d = Wild('d', exclude=[df, f(x).diff(x, 2)]) e = Wild('e', exclude=[df]) k = Wild('k', exclude=[df]) n = Wild('n', exclude=[x, f(x), df]) c1 = Wild('c1', exclude=[x]) a2 = Wild('a2', exclude=[x, f(x), df]) b2 = Wild('b2', exclude=[x, f(x), df]) c2 = Wild('c2', exclude=[x, f(x), df]) d2 = Wild('d2', exclude=[x, f(x), df]) a3 = Wild('a3', exclude=[f(x), df, f(x).diff(x, 2)]) b3 = Wild('b3', exclude=[f(x), df, f(x).diff(x, 2)]) c3 = Wild('c3', exclude=[f(x), df, f(x).diff(x, 2)]) r3 = {'xi': xi, 'eta': eta} # Used for the lie_group hint boundary = {} # Used to extract initial conditions C1 = Symbol("C1") eq = expand(eq) # Preprocessing to get the initial conditions out if ics is not None: for funcarg in ics: # Separating derivatives if isinstance(funcarg, (Subs, Derivative)): # f(x).diff(x).subs(x, 0) is a Subs, but f(x).diff(x).subs(x, # y) is a Derivative if isinstance(funcarg, Subs): deriv = funcarg.expr old = funcarg.variables[0] new = funcarg.point[0] elif isinstance(funcarg, Derivative): deriv = funcarg # No information on this. Just assume it was x old = x new = funcarg.variables[0] if (isinstance(deriv, Derivative) and isinstance(deriv.args[0], AppliedUndef) and deriv.args[0].func == f and len(deriv.args[0].args) == 1 and old == x and not new.has(x) and all(i == deriv.variables[0] for i in deriv.variables) and not ics[funcarg].has(f)): dorder = ode_order(deriv, x) temp = 'f' + str(dorder) boundary.update({temp: new, temp + 'val': ics[funcarg]}) else: raise ValueError("Enter valid boundary conditions for Derivatives") # Separating functions elif isinstance(funcarg, AppliedUndef): if (funcarg.func == f and len(funcarg.args) == 1 and not funcarg.args[0].has(x) and not ics[funcarg].has(f)): boundary.update({'f0': funcarg.args[0], 'f0val': ics[funcarg]}) else: raise ValueError("Enter valid boundary conditions for Function") else: raise ValueError("Enter boundary conditions of the form ics={f(point}: value, f(x).diff(x, order).subs(x, point): value}") # Precondition to try remove f(x) from highest order derivative reduced_eq = None if eq.is_Add: deriv_coef = eq.coeff(f(x).diff(x, order)) if deriv_coef not in (1, 0): r = deriv_coef.match(a*f(x)**c1) if r and r[c1]: den = f(x)**r[c1] reduced_eq = Add(*[arg/den for arg in eq.args]) if not reduced_eq: reduced_eq = eq if order == 1: ## Linear case: a(x)*y'+b(x)*y+c(x) == 0 if eq.is_Add: ind, dep = reduced_eq.as_independent(f) else: u = Dummy('u') ind, dep = (reduced_eq + u).as_independent(f) ind, dep = [tmp.subs(u, 0) for tmp in [ind, dep]] r = {a: dep.coeff(df), b: dep.coeff(f(x)), c: ind} # double check f[a] since the preconditioning may have failed if not r[a].has(f) and not r[b].has(f) and ( r[a]*df + r[b]*f(x) + r[c]).expand() - reduced_eq == 0: r['a'] = a r['b'] = b r['c'] = c matching_hints["1st_linear"] = r matching_hints["1st_linear_Integral"] = r ## Bernoulli case: a(x)*y'+b(x)*y+c(x)*y**n == 0 r = collect( reduced_eq, f(x), exact=True).match(a*df + b*f(x) + c*f(x)**n) if r and r[c] != 0 and r[n] != 1: # See issue 4676 r['a'] = a r['b'] = b r['c'] = c r['n'] = n matching_hints["Bernoulli"] = r matching_hints["Bernoulli_Integral"] = r ## Riccati special n == -2 case: a2*y'+b2*y**2+c2*y/x+d2/x**2 == 0 r = collect(reduced_eq, f(x), exact=True).match(a2*df + b2*f(x)**2 + c2*f(x)/x + d2/x**2) if r and r[b2] != 0 and (r[c2] != 0 or r[d2] != 0): r['a2'] = a2 r['b2'] = b2 r['c2'] = c2 r['d2'] = d2 matching_hints["Riccati_special_minus2"] = r # NON-REDUCED FORM OF EQUATION matches r = collect(eq, df, exact=True).match(d + e * df) if r: r['d'] = d r['e'] = e r['y'] = y r[d] = r[d].subs(f(x), y) r[e] = r[e].subs(f(x), y) # FIRST ORDER POWER SERIES WHICH NEEDS INITIAL CONDITIONS # TODO: Hint first order series should match only if d/e is analytic. # For now, only d/e and (d/e).diff(arg) is checked for existence at # at a given point. # This is currently done internally in ode_1st_power_series. point = boundary.get('f0', 0) value = boundary.get('f0val', C1) check = cancel(r[d]/r[e]) check1 = check.subs({x: point, y: value}) if not check1.has(oo) and not check1.has(zoo) and \ not check1.has(NaN) and not check1.has(-oo): check2 = (check1.diff(x)).subs({x: point, y: value}) if not check2.has(oo) and not check2.has(zoo) and \ not check2.has(NaN) and not check2.has(-oo): rseries = r.copy() rseries.update({'terms': terms, 'f0': point, 'f0val': value}) matching_hints["1st_power_series"] = rseries r3.update(r) ## Exact Differential Equation: P(x, y) + Q(x, y)*y' = 0 where # dP/dy == dQ/dx try: if r[d] != 0: numerator = simplify(r[d].diff(y) - r[e].diff(x)) # The following few conditions try to convert a non-exact # differential equation into an exact one. # References : Differential equations with applications # and historical notes - George E. Simmons if numerator: # If (dP/dy - dQ/dx) / Q = f(x) # then exp(integral(f(x))*equation becomes exact factor = simplify(numerator/r[e]) variables = factor.free_symbols if len(variables) == 1 and x == variables.pop(): factor = exp(Integral(factor).doit()) r[d] *= factor r[e] *= factor matching_hints["1st_exact"] = r matching_hints["1st_exact_Integral"] = r else: # If (dP/dy - dQ/dx) / -P = f(y) # then exp(integral(f(y))*equation becomes exact factor = simplify(-numerator/r[d]) variables = factor.free_symbols if len(variables) == 1 and y == variables.pop(): factor = exp(Integral(factor).doit()) r[d] *= factor r[e] *= factor matching_hints["1st_exact"] = r matching_hints["1st_exact_Integral"] = r else: matching_hints["1st_exact"] = r matching_hints["1st_exact_Integral"] = r except NotImplementedError: # Differentiating the coefficients might fail because of things # like f(2*x).diff(x). See issue 4624 and issue 4719. pass # Any first order ODE can be ideally solved by the Lie Group # method matching_hints["lie_group"] = r3 # This match is used for several cases below; we now collect on # f(x) so the matching works. r = collect(reduced_eq, df, exact=True).match(d + e*df) if r: # Using r[d] and r[e] without any modification for hints # linear-coefficients and separable-reduced. num, den = r[d], r[e] # ODE = d/e + df r['d'] = d r['e'] = e r['y'] = y r[d] = num.subs(f(x), y) r[e] = den.subs(f(x), y) ## Separable Case: y' == P(y)*Q(x) r[d] = separatevars(r[d]) r[e] = separatevars(r[e]) # m1[coeff]*m1[x]*m1[y] + m2[coeff]*m2[x]*m2[y]*y' m1 = separatevars(r[d], dict=True, symbols=(x, y)) m2 = separatevars(r[e], dict=True, symbols=(x, y)) if m1 and m2: r1 = {'m1': m1, 'm2': m2, 'y': y} matching_hints["separable"] = r1 matching_hints["separable_Integral"] = r1 ## First order equation with homogeneous coefficients: # dy/dx == F(y/x) or dy/dx == F(x/y) ordera = homogeneous_order(r[d], x, y) if ordera is not None: orderb = homogeneous_order(r[e], x, y) if ordera == orderb: # u1=y/x and u2=x/y u1 = Dummy('u1') u2 = Dummy('u2') s = "1st_homogeneous_coeff_subs" s1 = s + "_dep_div_indep" s2 = s + "_indep_div_dep" if simplify((r[d] + u1*r[e]).subs({x: 1, y: u1})) != 0: matching_hints[s1] = r matching_hints[s1 + "_Integral"] = r if simplify((r[e] + u2*r[d]).subs({x: u2, y: 1})) != 0: matching_hints[s2] = r matching_hints[s2 + "_Integral"] = r if s1 in matching_hints and s2 in matching_hints: matching_hints["1st_homogeneous_coeff_best"] = r ## Linear coefficients of the form # y'+ F((a*x + b*y + c)/(a'*x + b'y + c')) = 0 # that can be reduced to homogeneous form. F = num/den params = _linear_coeff_match(F, func) if params: xarg, yarg = params u = Dummy('u') t = Dummy('t') # Dummy substitution for df and f(x). dummy_eq = reduced_eq.subs(((df, t), (f(x), u))) reps = ((x, x + xarg), (u, u + yarg), (t, df), (u, f(x))) dummy_eq = simplify(dummy_eq.subs(reps)) # get the re-cast values for e and d r2 = collect(expand(dummy_eq), [df, f(x)]).match(e*df + d) if r2: orderd = homogeneous_order(r2[d], x, f(x)) if orderd is not None: ordere = homogeneous_order(r2[e], x, f(x)) if orderd == ordere: # Match arguments are passed in such a way that it # is coherent with the already existing homogeneous # functions. r2[d] = r2[d].subs(f(x), y) r2[e] = r2[e].subs(f(x), y) r2.update({'xarg': xarg, 'yarg': yarg, 'd': d, 'e': e, 'y': y}) matching_hints["linear_coefficients"] = r2 matching_hints["linear_coefficients_Integral"] = r2 ## Equation of the form y' + (y/x)*H(x^n*y) = 0 # that can be reduced to separable form factor = simplify(x/f(x)*num/den) # Try representing factor in terms of x^n*y # where n is lowest power of x in factor; # first remove terms like sqrt(2)*3 from factor.atoms(Mul) u = None for mul in ordered(factor.atoms(Mul)): if mul.has(x): _, u = mul.as_independent(x, f(x)) break if u and u.has(f(x)): h = x**(degree(Poly(u.subs(f(x), y), gen=x)))*f(x) p = Wild('p') if (u/h == 1) or ((u/h).simplify().match(x**p)): t = Dummy('t') r2 = {'t': t} xpart, ypart = u.as_independent(f(x)) test = factor.subs(((u, t), (1/u, 1/t))) free = test.free_symbols if len(free) == 1 and free.pop() == t: r2.update({'power': xpart.as_base_exp()[1], 'u': test}) matching_hints["separable_reduced"] = r2 matching_hints["separable_reduced_Integral"] = r2 ## Almost-linear equation of the form f(x)*g(y)*y' + k(x)*l(y) + m(x) = 0 r = collect(eq, [df, f(x)]).match(e*df + d) if r: r2 = r.copy() r2[c] = S.Zero if r2[d].is_Add: # Separate the terms having f(x) to r[d] and # remaining to r[c] no_f, r2[d] = r2[d].as_independent(f(x)) r2[c] += no_f factor = simplify(r2[d].diff(f(x))/r[e]) if factor and not factor.has(f(x)): r2[d] = factor_terms(r2[d]) u = r2[d].as_independent(f(x), as_Add=False)[1] r2.update({'a': e, 'b': d, 'c': c, 'u': u}) r2[d] /= u r2[e] /= u.diff(f(x)) matching_hints["almost_linear"] = r2 matching_hints["almost_linear_Integral"] = r2 elif order == 2: # Liouville ODE in the form # f(x).diff(x, 2) + g(f(x))*(f(x).diff(x))**2 + h(x)*f(x).diff(x) # See Goldstein and Braun, "Advanced Methods for the Solution of # Differential Equations", pg. 98 s = d*f(x).diff(x, 2) + e*df**2 + k*df r = reduced_eq.match(s) if r and r[d] != 0: y = Dummy('y') g = simplify(r[e]/r[d]).subs(f(x), y) h = simplify(r[k]/r[d]).subs(f(x), y) if y in h.free_symbols or x in g.free_symbols: pass else: r = {'g': g, 'h': h, 'y': y} matching_hints["Liouville"] = r matching_hints["Liouville_Integral"] = r # Homogeneous second order differential equation of the form # a3*f(x).diff(x, 2) + b3*f(x).diff(x) + c3, where # for simplicity, a3, b3 and c3 are assumed to be polynomials. # It has a definite power series solution at point x0 if, b3/a3 and c3/a3 # are analytic at x0. deq = a3*(f(x).diff(x, 2)) + b3*df + c3*f(x) r = collect(reduced_eq, [f(x).diff(x, 2), f(x).diff(x), f(x)]).match(deq) ordinary = False if r and r[a3] != 0: if all([r[key].is_polynomial() for key in r]): p = cancel(r[b3]/r[a3]) # Used below q = cancel(r[c3]/r[a3]) # Used below point = kwargs.get('x0', 0) check = p.subs(x, point) if not check.has(oo) and not check.has(NaN) and \ not check.has(zoo) and not check.has(-oo): check = q.subs(x, point) if not check.has(oo) and not check.has(NaN) and \ not check.has(zoo) and not check.has(-oo): ordinary = True r.update({'a3': a3, 'b3': b3, 'c3': c3, 'x0': point, 'terms': terms}) matching_hints["2nd_power_series_ordinary"] = r # Checking if the differential equation has a regular singular point # at x0. It has a regular singular point at x0, if (b3/a3)*(x - x0) # and (c3/a3)*((x - x0)**2) are analytic at x0. if not ordinary: p = cancel((x - point)*p) check = p.subs(x, point) if not check.has(oo) and not check.has(NaN) and \ not check.has(zoo) and not check.has(-oo): q = cancel(((x - point)**2)*q) check = q.subs(x, point) if not check.has(oo) and not check.has(NaN) and \ not check.has(zoo) and not check.has(-oo): coeff_dict = {'p': p, 'q': q, 'x0': point, 'terms': terms} matching_hints["2nd_power_series_regular"] = coeff_dict if order > 0: # Any ODE that can be solved with a combination of algebra and # integrals e.g.: # d^3/dx^3(x y) = F(x) r = _nth_algebraic_match(reduced_eq, func) if r['solutions']: matching_hints['nth_algebraic'] = r matching_hints['nth_algebraic_Integral'] = r # nth order linear ODE # a_n(x)y^(n) + ... + a_1(x)y' + a_0(x)y = F(x) = b r = _nth_linear_match(reduced_eq, func, order) # Constant coefficient case (a_i is constant for all i) if r and not any(r[i].has(x) for i in r if i >= 0): # Inhomogeneous case: F(x) is not identically 0 if r[-1]: undetcoeff = _undetermined_coefficients_match(r[-1], x) s = "nth_linear_constant_coeff_variation_of_parameters" matching_hints[s] = r matching_hints[s + "_Integral"] = r if undetcoeff['test']: r['trialset'] = undetcoeff['trialset'] matching_hints[ "nth_linear_constant_coeff_undetermined_coefficients" ] = r # Homogeneous case: F(x) is identically 0 else: matching_hints["nth_linear_constant_coeff_homogeneous"] = r # nth order Euler equation a_n*x**n*y^(n) + ... + a_1*x*y' + a_0*y = F(x) #In case of Homogeneous euler equation F(x) = 0 def _test_term(coeff, order): r""" Linear Euler ODEs have the form K*x**order*diff(y(x),x,order) = F(x), where K is independent of x and y(x), order>= 0. So we need to check that for each term, coeff == K*x**order from some K. We have a few cases, since coeff may have several different types. """ if order < 0: raise ValueError("order should be greater than 0") if coeff == 0: return True if order == 0: if x in coeff.free_symbols: return False return True if coeff.is_Mul: if coeff.has(f(x)): return False return x**order in coeff.args elif coeff.is_Pow: return coeff.as_base_exp() == (x, order) elif order == 1: return x == coeff return False # Find coefficient for higest derivative, multiply coefficients to # bring the equation into Euler form if possible r_rescaled = None if r is not None: coeff = r[order] factor = x**order / coeff r_rescaled = {i: factor*r[i] for i in r} if r_rescaled and not any(not _test_term(r_rescaled[i], i) for i in r_rescaled if i != 'trialset' and i >= 0): if not r_rescaled[-1]: matching_hints["nth_linear_euler_eq_homogeneous"] = r_rescaled else: matching_hints["nth_linear_euler_eq_nonhomogeneous_variation_of_parameters"] = r_rescaled matching_hints["nth_linear_euler_eq_nonhomogeneous_variation_of_parameters_Integral"] = r_rescaled e, re = posify(r_rescaled[-1].subs(x, exp(x))) undetcoeff = _undetermined_coefficients_match(e.subs(re), x) if undetcoeff['test']: r_rescaled['trialset'] = undetcoeff['trialset'] matching_hints["nth_linear_euler_eq_nonhomogeneous_undetermined_coefficients"] = r_rescaled # Order keys based on allhints. retlist = [i for i in allhints if i in matching_hints] if dict: # Dictionaries are ordered arbitrarily, so make note of which # hint would come first for dsolve(). Use an ordered dict in Py 3. matching_hints["default"] = retlist[0] if retlist else None matching_hints["ordered_hints"] = tuple(retlist) return matching_hints else: return tuple(retlist) def classify_sysode(eq, funcs=None, **kwargs): r""" Returns a dictionary of parameter names and values that define the system of ordinary differential equations in ``eq``. The parameters are further used in :py:meth:`~sympy.solvers.ode.dsolve` for solving that system. The parameter names and values are: 'is_linear' (boolean), which tells whether the given system is linear. Note that "linear" here refers to the operator: terms such as ``x*diff(x,t)`` are nonlinear, whereas terms like ``sin(t)*diff(x,t)`` are still linear operators. 'func' (list) contains the :py:class:`~sympy.core.function.Function`s that appear with a derivative in the ODE, i.e. those that we are trying to solve the ODE for. 'order' (dict) with the maximum derivative for each element of the 'func' parameter. 'func_coeff' (dict) with the coefficient for each triple ``(equation number, function, order)```. The coefficients are those subexpressions that do not appear in 'func', and hence can be considered constant for purposes of ODE solving. 'eq' (list) with the equations from ``eq``, sympified and transformed into expressions (we are solving for these expressions to be zero). 'no_of_equations' (int) is the number of equations (same as ``len(eq)``). 'type_of_equation' (string) is an internal classification of the type of ODE. References ========== -http://eqworld.ipmnet.ru/en/solutions/sysode/sode-toc1.htm -A. D. Polyanin and A. V. Manzhirov, Handbook of Mathematics for Engineers and Scientists Examples ======== >>> from sympy import Function, Eq, symbols, diff >>> from sympy.solvers.ode import classify_sysode >>> from sympy.abc import t >>> f, x, y = symbols('f, x, y', cls=Function) >>> k, l, m, n = symbols('k, l, m, n', Integer=True) >>> x1 = diff(x(t), t) ; y1 = diff(y(t), t) >>> x2 = diff(x(t), t, t) ; y2 = diff(y(t), t, t) >>> eq = (Eq(5*x1, 12*x(t) - 6*y(t)), Eq(2*y1, 11*x(t) + 3*y(t))) >>> classify_sysode(eq) {'eq': [-12*x(t) + 6*y(t) + 5*Derivative(x(t), t), -11*x(t) - 3*y(t) + 2*Derivative(y(t), t)], 'func': [x(t), y(t)], 'func_coeff': {(0, x(t), 0): -12, (0, x(t), 1): 5, (0, y(t), 0): 6, (0, y(t), 1): 0, (1, x(t), 0): -11, (1, x(t), 1): 0, (1, y(t), 0): -3, (1, y(t), 1): 2}, 'is_linear': True, 'no_of_equation': 2, 'order': {x(t): 1, y(t): 1}, 'type_of_equation': 'type1'} >>> eq = (Eq(diff(x(t),t), 5*t*x(t) + t**2*y(t)), Eq(diff(y(t),t), -t**2*x(t) + 5*t*y(t))) >>> classify_sysode(eq) {'eq': [-t**2*y(t) - 5*t*x(t) + Derivative(x(t), t), t**2*x(t) - 5*t*y(t) + Derivative(y(t), t)], 'func': [x(t), y(t)], 'func_coeff': {(0, x(t), 0): -5*t, (0, x(t), 1): 1, (0, y(t), 0): -t**2, (0, y(t), 1): 0, (1, x(t), 0): t**2, (1, x(t), 1): 0, (1, y(t), 0): -5*t, (1, y(t), 1): 1}, 'is_linear': True, 'no_of_equation': 2, 'order': {x(t): 1, y(t): 1}, 'type_of_equation': 'type4'} """ # Sympify equations and convert iterables of equations into # a list of equations def _sympify(eq): return list(map(sympify, eq if iterable(eq) else [eq])) eq, funcs = (_sympify(w) for w in [eq, funcs]) for i, fi in enumerate(eq): if isinstance(fi, Equality): eq[i] = fi.lhs - fi.rhs matching_hints = {"no_of_equation":i+1} matching_hints['eq'] = eq if i==0: raise ValueError("classify_sysode() works for systems of ODEs. " "For scalar ODEs, classify_ode should be used") t = list(list(eq[0].atoms(Derivative))[0].atoms(Symbol))[0] # find all the functions if not given order = dict() if funcs==[None]: funcs = [] for eqs in eq: derivs = eqs.atoms(Derivative) func = set().union(*[d.atoms(AppliedUndef) for d in derivs]) for func_ in func: funcs.append(func_) funcs = list(set(funcs)) if len(funcs) < len(eq): raise ValueError("Number of functions given is less than number of equations %s" % funcs) func_dict = dict() for func in funcs: if not order.get(func, False): max_order = 0 for i, eqs_ in enumerate(eq): order_ = ode_order(eqs_,func) if max_order < order_: max_order = order_ eq_no = i if eq_no in func_dict: list_func = [] list_func.append(func_dict[eq_no]) list_func.append(func) func_dict[eq_no] = list_func else: func_dict[eq_no] = func order[func] = max_order funcs = [func_dict[i] for i in range(len(func_dict))] matching_hints['func'] = funcs for func in funcs: if isinstance(func, list): for func_elem in func: if len(func_elem.args) != 1: raise ValueError("dsolve() and classify_sysode() work with " "functions of one variable only, not %s" % func) else: if func and len(func.args) != 1: raise ValueError("dsolve() and classify_sysode() work with " "functions of one variable only, not %s" % func) # find the order of all equation in system of odes matching_hints["order"] = order # find coefficients of terms f(t), diff(f(t),t) and higher derivatives # and similarly for other functions g(t), diff(g(t),t) in all equations. # Here j denotes the equation number, funcs[l] denotes the function about # which we are talking about and k denotes the order of function funcs[l] # whose coefficient we are calculating. def linearity_check(eqs, j, func, is_linear_): for k in range(order[func] + 1): func_coef[j, func, k] = collect(eqs.expand(), [diff(func, t, k)]).coeff(diff(func, t, k)) if is_linear_ == True: if func_coef[j, func, k] == 0: if k == 0: coef = eqs.as_independent(func, as_Add=True)[1] for xr in range(1, ode_order(eqs,func) + 1): coef -= eqs.as_independent(diff(func, t, xr), as_Add=True)[1] if coef != 0: is_linear_ = False else: if eqs.as_independent(diff(func, t, k), as_Add=True)[1]: is_linear_ = False else: for func_ in funcs: if isinstance(func_, list): for elem_func_ in func_: dep = func_coef[j, func, k].as_independent(elem_func_, as_Add=True)[1] if dep != 0: is_linear_ = False else: dep = func_coef[j, func, k].as_independent(func_, as_Add=True)[1] if dep != 0: is_linear_ = False return is_linear_ func_coef = {} is_linear = True for j, eqs in enumerate(eq): for func in funcs: if isinstance(func, list): for func_elem in func: is_linear = linearity_check(eqs, j, func_elem, is_linear) else: is_linear = linearity_check(eqs, j, func, is_linear) matching_hints['func_coeff'] = func_coef matching_hints['is_linear'] = is_linear if len(set(order.values()))==1: order_eq = list(matching_hints['order'].values())[0] if matching_hints['is_linear'] == True: if matching_hints['no_of_equation'] == 2: if order_eq == 1: type_of_equation = check_linear_2eq_order1(eq, funcs, func_coef) elif order_eq == 2: type_of_equation = check_linear_2eq_order2(eq, funcs, func_coef) else: type_of_equation = None elif matching_hints['no_of_equation'] == 3: if order_eq == 1: type_of_equation = check_linear_3eq_order1(eq, funcs, func_coef) if type_of_equation==None: type_of_equation = check_linear_neq_order1(eq, funcs, func_coef) else: type_of_equation = None else: if order_eq == 1: type_of_equation = check_linear_neq_order1(eq, funcs, func_coef) else: type_of_equation = None else: if matching_hints['no_of_equation'] == 2: if order_eq == 1: type_of_equation = check_nonlinear_2eq_order1(eq, funcs, func_coef) else: type_of_equation = None elif matching_hints['no_of_equation'] == 3: if order_eq == 1: type_of_equation = check_nonlinear_3eq_order1(eq, funcs, func_coef) else: type_of_equation = None else: type_of_equation = None else: type_of_equation = None matching_hints['type_of_equation'] = type_of_equation return matching_hints def check_linear_2eq_order1(eq, func, func_coef): x = func[0].func y = func[1].func fc = func_coef t = list(list(eq[0].atoms(Derivative))[0].atoms(Symbol))[0] r = dict() # for equations Eq(a1*diff(x(t),t), b1*x(t) + c1*y(t) + d1) # and Eq(a2*diff(y(t),t), b2*x(t) + c2*y(t) + d2) r['a1'] = fc[0,x(t),1] ; r['a2'] = fc[1,y(t),1] r['b1'] = -fc[0,x(t),0]/fc[0,x(t),1] ; r['b2'] = -fc[1,x(t),0]/fc[1,y(t),1] r['c1'] = -fc[0,y(t),0]/fc[0,x(t),1] ; r['c2'] = -fc[1,y(t),0]/fc[1,y(t),1] forcing = [S(0),S(0)] for i in range(2): for j in Add.make_args(eq[i]): if not j.has(x(t), y(t)): forcing[i] += j if not (forcing[0].has(t) or forcing[1].has(t)): # We can handle homogeneous case and simple constant forcings r['d1'] = forcing[0] r['d2'] = forcing[1] else: # Issue #9244: nonhomogeneous linear systems are not supported return None # Conditions to check for type 6 whose equations are Eq(diff(x(t),t), f(t)*x(t) + g(t)*y(t)) and # Eq(diff(y(t),t), a*[f(t) + a*h(t)]x(t) + a*[g(t) - h(t)]*y(t)) p = 0 q = 0 p1 = cancel(r['b2']/(cancel(r['b2']/r['c2']).as_numer_denom()[0])) p2 = cancel(r['b1']/(cancel(r['b1']/r['c1']).as_numer_denom()[0])) for n, i in enumerate([p1, p2]): for j in Mul.make_args(collect_const(i)): if not j.has(t): q = j if q and n==0: if ((r['b2']/j - r['b1'])/(r['c1'] - r['c2']/j)) == j: p = 1 elif q and n==1: if ((r['b1']/j - r['b2'])/(r['c2'] - r['c1']/j)) == j: p = 2 # End of condition for type 6 if r['d1']!=0 or r['d2']!=0: if not r['d1'].has(t) and not r['d2'].has(t): if all(not r[k].has(t) for k in 'a1 a2 b1 b2 c1 c2'.split()): # Equations for type 2 are Eq(a1*diff(x(t),t),b1*x(t)+c1*y(t)+d1) and Eq(a2*diff(y(t),t),b2*x(t)+c2*y(t)+d2) return "type2" else: return None else: if all(not r[k].has(t) for k in 'a1 a2 b1 b2 c1 c2'.split()): # Equations for type 1 are Eq(a1*diff(x(t),t),b1*x(t)+c1*y(t)) and Eq(a2*diff(y(t),t),b2*x(t)+c2*y(t)) return "type1" else: r['b1'] = r['b1']/r['a1'] ; r['b2'] = r['b2']/r['a2'] r['c1'] = r['c1']/r['a1'] ; r['c2'] = r['c2']/r['a2'] if (r['b1'] == r['c2']) and (r['c1'] == r['b2']): # Equation for type 3 are Eq(diff(x(t),t), f(t)*x(t) + g(t)*y(t)) and Eq(diff(y(t),t), g(t)*x(t) + f(t)*y(t)) return "type3" elif (r['b1'] == r['c2']) and (r['c1'] == -r['b2']) or (r['b1'] == -r['c2']) and (r['c1'] == r['b2']): # Equation for type 4 are Eq(diff(x(t),t), f(t)*x(t) + g(t)*y(t)) and Eq(diff(y(t),t), -g(t)*x(t) + f(t)*y(t)) return "type4" elif (not cancel(r['b2']/r['c1']).has(t) and not cancel((r['c2']-r['b1'])/r['c1']).has(t)) \ or (not cancel(r['b1']/r['c2']).has(t) and not cancel((r['c1']-r['b2'])/r['c2']).has(t)): # Equations for type 5 are Eq(diff(x(t),t), f(t)*x(t) + g(t)*y(t)) and Eq(diff(y(t),t), a*g(t)*x(t) + [f(t) + b*g(t)]*y(t) return "type5" elif p: return "type6" else: # Equations for type 7 are Eq(diff(x(t),t), f(t)*x(t) + g(t)*y(t)) and Eq(diff(y(t),t), h(t)*x(t) + p(t)*y(t)) return "type7" def check_linear_2eq_order2(eq, func, func_coef): x = func[0].func y = func[1].func fc = func_coef t = list(list(eq[0].atoms(Derivative))[0].atoms(Symbol))[0] r = dict() a = Wild('a', exclude=[1/t]) b = Wild('b', exclude=[1/t**2]) u = Wild('u', exclude=[t, t**2]) v = Wild('v', exclude=[t, t**2]) w = Wild('w', exclude=[t, t**2]) p = Wild('p', exclude=[t, t**2]) r['a1'] = fc[0,x(t),2] ; r['a2'] = fc[1,y(t),2] r['b1'] = fc[0,x(t),1] ; r['b2'] = fc[1,x(t),1] r['c1'] = fc[0,y(t),1] ; r['c2'] = fc[1,y(t),1] r['d1'] = fc[0,x(t),0] ; r['d2'] = fc[1,x(t),0] r['e1'] = fc[0,y(t),0] ; r['e2'] = fc[1,y(t),0] const = [S(0), S(0)] for i in range(2): for j in Add.make_args(eq[i]): if not (j.has(x(t)) or j.has(y(t))): const[i] += j r['f1'] = const[0] r['f2'] = const[1] if r['f1']!=0 or r['f2']!=0: if all(not r[k].has(t) for k in 'a1 a2 d1 d2 e1 e2 f1 f2'.split()) \ and r['b1']==r['c1']==r['b2']==r['c2']==0: return "type2" elif all(not r[k].has(t) for k in 'a1 a2 b1 b2 c1 c2 d1 d2 e1 e1'.split()): p = [S(0), S(0)] ; q = [S(0), S(0)] for n, e in enumerate([r['f1'], r['f2']]): if e.has(t): tpart = e.as_independent(t, Mul)[1] for i in Mul.make_args(tpart): if i.has(exp): b, e = i.as_base_exp() co = e.coeff(t) if co and not co.has(t) and co.has(I): p[n] = 1 else: q[n] = 1 else: q[n] = 1 else: q[n] = 1 if p[0]==1 and p[1]==1 and q[0]==0 and q[1]==0: return "type4" else: return None else: return None else: if r['b1']==r['b2']==r['c1']==r['c2']==0 and all(not r[k].has(t) \ for k in 'a1 a2 d1 d2 e1 e2'.split()): return "type1" elif r['b1']==r['e1']==r['c2']==r['d2']==0 and all(not r[k].has(t) \ for k in 'a1 a2 b2 c1 d1 e2'.split()) and r['c1'] == -r['b2'] and \ r['d1'] == r['e2']: return "type3" elif cancel(-r['b2']/r['d2'])==t and cancel(-r['c1']/r['e1'])==t and not \ (r['d2']/r['a2']).has(t) and not (r['e1']/r['a1']).has(t) and \ r['b1']==r['d1']==r['c2']==r['e2']==0: return "type5" elif ((r['a1']/r['d1']).expand()).match((p*(u*t**2+v*t+w)**2).expand()) and not \ (cancel(r['a1']*r['d2']/(r['a2']*r['d1']))).has(t) and not (r['d1']/r['e1']).has(t) and not \ (r['d2']/r['e2']).has(t) and r['b1'] == r['b2'] == r['c1'] == r['c2'] == 0: return "type10" elif not cancel(r['d1']/r['e1']).has(t) and not cancel(r['d2']/r['e2']).has(t) and not \ cancel(r['d1']*r['a2']/(r['d2']*r['a1'])).has(t) and r['b1']==r['b2']==r['c1']==r['c2']==0: return "type6" elif not cancel(r['b1']/r['c1']).has(t) and not cancel(r['b2']/r['c2']).has(t) and not \ cancel(r['b1']*r['a2']/(r['b2']*r['a1'])).has(t) and r['d1']==r['d2']==r['e1']==r['e2']==0: return "type7" elif cancel(-r['b2']/r['d2'])==t and cancel(-r['c1']/r['e1'])==t and not \ cancel(r['e1']*r['a2']/(r['d2']*r['a1'])).has(t) and r['e1'].has(t) \ and r['b1']==r['d1']==r['c2']==r['e2']==0: return "type8" elif (r['b1']/r['a1']).match(a/t) and (r['b2']/r['a2']).match(a/t) and not \ (r['b1']/r['c1']).has(t) and not (r['b2']/r['c2']).has(t) and \ (r['d1']/r['a1']).match(b/t**2) and (r['d2']/r['a2']).match(b/t**2) \ and not (r['d1']/r['e1']).has(t) and not (r['d2']/r['e2']).has(t): return "type9" elif -r['b1']/r['d1']==-r['c1']/r['e1']==-r['b2']/r['d2']==-r['c2']/r['e2']==t: return "type11" else: return None def check_linear_3eq_order1(eq, func, func_coef): x = func[0].func y = func[1].func z = func[2].func fc = func_coef t = list(list(eq[0].atoms(Derivative))[0].atoms(Symbol))[0] r = dict() r['a1'] = fc[0,x(t),1]; r['a2'] = fc[1,y(t),1]; r['a3'] = fc[2,z(t),1] r['b1'] = fc[0,x(t),0]; r['b2'] = fc[1,x(t),0]; r['b3'] = fc[2,x(t),0] r['c1'] = fc[0,y(t),0]; r['c2'] = fc[1,y(t),0]; r['c3'] = fc[2,y(t),0] r['d1'] = fc[0,z(t),0]; r['d2'] = fc[1,z(t),0]; r['d3'] = fc[2,z(t),0] forcing = [S(0), S(0), S(0)] for i in range(3): for j in Add.make_args(eq[i]): if not j.has(x(t), y(t), z(t)): forcing[i] += j if forcing[0].has(t) or forcing[1].has(t) or forcing[2].has(t): # We can handle homogeneous case and simple constant forcings. # Issue #9244: nonhomogeneous linear systems are not supported return None if all(not r[k].has(t) for k in 'a1 a2 a3 b1 b2 b3 c1 c2 c3 d1 d2 d3'.split()): if r['c1']==r['d1']==r['d2']==0: return 'type1' elif r['c1'] == -r['b2'] and r['d1'] == -r['b3'] and r['d2'] == -r['c3'] \ and r['b1'] == r['c2'] == r['d3'] == 0: return 'type2' elif r['b1'] == r['c2'] == r['d3'] == 0 and r['c1']/r['a1'] == -r['d1']/r['a1'] \ and r['d2']/r['a2'] == -r['b2']/r['a2'] and r['b3']/r['a3'] == -r['c3']/r['a3']: return 'type3' else: return None else: for k1 in 'c1 d1 b2 d2 b3 c3'.split(): if r[k1] == 0: continue else: if all(not cancel(r[k1]/r[k]).has(t) for k in 'd1 b2 d2 b3 c3'.split() if r[k]!=0) \ and all(not cancel(r[k1]/(r['b1'] - r[k])).has(t) for k in 'b1 c2 d3'.split() if r['b1']!=r[k]): return 'type4' else: break return None def check_linear_neq_order1(eq, func, func_coef): x = func[0].func y = func[1].func z = func[2].func fc = func_coef t = list(list(eq[0].atoms(Derivative))[0].atoms(Symbol))[0] r = dict() n = len(eq) for i in range(n): for j in range(n): if (fc[i,func[j],0]/fc[i,func[i],1]).has(t): return None if len(eq)==3: return 'type6' return 'type1' def check_nonlinear_2eq_order1(eq, func, func_coef): t = list(list(eq[0].atoms(Derivative))[0].atoms(Symbol))[0] f = Wild('f') g = Wild('g') u, v = symbols('u, v', cls=Dummy) def check_type(x, y): r1 = eq[0].match(t*diff(x(t),t) - x(t) + f) r2 = eq[1].match(t*diff(y(t),t) - y(t) + g) if not (r1 and r2): r1 = eq[0].match(diff(x(t),t) - x(t)/t + f/t) r2 = eq[1].match(diff(y(t),t) - y(t)/t + g/t) if not (r1 and r2): r1 = (-eq[0]).match(t*diff(x(t),t) - x(t) + f) r2 = (-eq[1]).match(t*diff(y(t),t) - y(t) + g) if not (r1 and r2): r1 = (-eq[0]).match(diff(x(t),t) - x(t)/t + f/t) r2 = (-eq[1]).match(diff(y(t),t) - y(t)/t + g/t) if r1 and r2 and not (r1[f].subs(diff(x(t),t),u).subs(diff(y(t),t),v).has(t) \ or r2[g].subs(diff(x(t),t),u).subs(diff(y(t),t),v).has(t)): return 'type5' else: return None for func_ in func: if isinstance(func_, list): x = func[0][0].func y = func[0][1].func eq_type = check_type(x, y) if not eq_type: eq_type = check_type(y, x) return eq_type x = func[0].func y = func[1].func fc = func_coef n = Wild('n', exclude=[x(t),y(t)]) f1 = Wild('f1', exclude=[v,t]) f2 = Wild('f2', exclude=[v,t]) g1 = Wild('g1', exclude=[u,t]) g2 = Wild('g2', exclude=[u,t]) for i in range(2): eqs = 0 for terms in Add.make_args(eq[i]): eqs += terms/fc[i,func[i],1] eq[i] = eqs r = eq[0].match(diff(x(t),t) - x(t)**n*f) if r: g = (diff(y(t),t) - eq[1])/r[f] if r and not (g.has(x(t)) or g.subs(y(t),v).has(t) or r[f].subs(x(t),u).subs(y(t),v).has(t)): return 'type1' r = eq[0].match(diff(x(t),t) - exp(n*x(t))*f) if r: g = (diff(y(t),t) - eq[1])/r[f] if r and not (g.has(x(t)) or g.subs(y(t),v).has(t) or r[f].subs(x(t),u).subs(y(t),v).has(t)): return 'type2' g = Wild('g') r1 = eq[0].match(diff(x(t),t) - f) r2 = eq[1].match(diff(y(t),t) - g) if r1 and r2 and not (r1[f].subs(x(t),u).subs(y(t),v).has(t) or \ r2[g].subs(x(t),u).subs(y(t),v).has(t)): return 'type3' r1 = eq[0].match(diff(x(t),t) - f) r2 = eq[1].match(diff(y(t),t) - g) num, den = ( (r1[f].subs(x(t),u).subs(y(t),v))/ (r2[g].subs(x(t),u).subs(y(t),v))).as_numer_denom() R1 = num.match(f1*g1) R2 = den.match(f2*g2) phi = (r1[f].subs(x(t),u).subs(y(t),v))/num if R1 and R2: return 'type4' return None def check_nonlinear_2eq_order2(eq, func, func_coef): return None def check_nonlinear_3eq_order1(eq, func, func_coef): x = func[0].func y = func[1].func z = func[2].func fc = func_coef t = list(list(eq[0].atoms(Derivative))[0].atoms(Symbol))[0] u, v, w = symbols('u, v, w', cls=Dummy) a = Wild('a', exclude=[x(t), y(t), z(t), t]) b = Wild('b', exclude=[x(t), y(t), z(t), t]) c = Wild('c', exclude=[x(t), y(t), z(t), t]) f = Wild('f') F1 = Wild('F1') F2 = Wild('F2') F3 = Wild('F3') for i in range(3): eqs = 0 for terms in Add.make_args(eq[i]): eqs += terms/fc[i,func[i],1] eq[i] = eqs r1 = eq[0].match(diff(x(t),t) - a*y(t)*z(t)) r2 = eq[1].match(diff(y(t),t) - b*z(t)*x(t)) r3 = eq[2].match(diff(z(t),t) - c*x(t)*y(t)) if r1 and r2 and r3: num1, den1 = r1[a].as_numer_denom() num2, den2 = r2[b].as_numer_denom() num3, den3 = r3[c].as_numer_denom() if solve([num1*u-den1*(v-w), num2*v-den2*(w-u), num3*w-den3*(u-v)],[u, v]): return 'type1' r = eq[0].match(diff(x(t),t) - y(t)*z(t)*f) if r: r1 = collect_const(r[f]).match(a*f) r2 = ((diff(y(t),t) - eq[1])/r1[f]).match(b*z(t)*x(t)) r3 = ((diff(z(t),t) - eq[2])/r1[f]).match(c*x(t)*y(t)) if r1 and r2 and r3: num1, den1 = r1[a].as_numer_denom() num2, den2 = r2[b].as_numer_denom() num3, den3 = r3[c].as_numer_denom() if solve([num1*u-den1*(v-w), num2*v-den2*(w-u), num3*w-den3*(u-v)],[u, v]): return 'type2' r = eq[0].match(diff(x(t),t) - (F2-F3)) if r: r1 = collect_const(r[F2]).match(c*F2) r1.update(collect_const(r[F3]).match(b*F3)) if r1: if eq[1].has(r1[F2]) and not eq[1].has(r1[F3]): r1[F2], r1[F3] = r1[F3], r1[F2] r1[c], r1[b] = -r1[b], -r1[c] r2 = eq[1].match(diff(y(t),t) - a*r1[F3] + r1[c]*F1) if r2: r3 = (eq[2] == diff(z(t),t) - r1[b]*r2[F1] + r2[a]*r1[F2]) if r1 and r2 and r3: return 'type3' r = eq[0].match(diff(x(t),t) - z(t)*F2 + y(t)*F3) if r: r1 = collect_const(r[F2]).match(c*F2) r1.update(collect_const(r[F3]).match(b*F3)) if r1: if eq[1].has(r1[F2]) and not eq[1].has(r1[F3]): r1[F2], r1[F3] = r1[F3], r1[F2] r1[c], r1[b] = -r1[b], -r1[c] r2 = (diff(y(t),t) - eq[1]).match(a*x(t)*r1[F3] - r1[c]*z(t)*F1) if r2: r3 = (diff(z(t),t) - eq[2] == r1[b]*y(t)*r2[F1] - r2[a]*x(t)*r1[F2]) if r1 and r2 and r3: return 'type4' r = (diff(x(t),t) - eq[0]).match(x(t)*(F2 - F3)) if r: r1 = collect_const(r[F2]).match(c*F2) r1.update(collect_const(r[F3]).match(b*F3)) if r1: if eq[1].has(r1[F2]) and not eq[1].has(r1[F3]): r1[F2], r1[F3] = r1[F3], r1[F2] r1[c], r1[b] = -r1[b], -r1[c] r2 = (diff(y(t),t) - eq[1]).match(y(t)*(a*r1[F3] - r1[c]*F1)) if r2: r3 = (diff(z(t),t) - eq[2] == z(t)*(r1[b]*r2[F1] - r2[a]*r1[F2])) if r1 and r2 and r3: return 'type5' return None def check_nonlinear_3eq_order2(eq, func, func_coef): return None def checksysodesol(eqs, sols, func=None): r""" Substitutes corresponding ``sols`` for each functions into each ``eqs`` and checks that the result of substitutions for each equation is ``0``. The equations and solutions passed can be any iterable. This only works when each ``sols`` have one function only, like `x(t)` or `y(t)`. For each function, ``sols`` can have a single solution or a list of solutions. In most cases it will not be necessary to explicitly identify the function, but if the function cannot be inferred from the original equation it can be supplied through the ``func`` argument. When a sequence of equations is passed, the same sequence is used to return the result for each equation with each function substituted with corresponding solutions. It tries the following method to find zero equivalence for each equation: Substitute the solutions for functions, like `x(t)` and `y(t)` into the original equations containing those functions. This function returns a tuple. The first item in the tuple is ``True`` if the substitution results for each equation is ``0``, and ``False`` otherwise. The second item in the tuple is what the substitution results in. Each element of the ``list`` should always be ``0`` corresponding to each equation if the first item is ``True``. Note that sometimes this function may return ``False``, but with an expression that is identically equal to ``0``, instead of returning ``True``. This is because :py:meth:`~sympy.simplify.simplify.simplify` cannot reduce the expression to ``0``. If an expression returned by each function vanishes identically, then ``sols`` really is a solution to ``eqs``. If this function seems to hang, it is probably because of a difficult simplification. Examples ======== >>> from sympy import Eq, diff, symbols, sin, cos, exp, sqrt, S, Function >>> from sympy.solvers.ode import checksysodesol >>> C1, C2 = symbols('C1:3') >>> t = symbols('t') >>> x, y = symbols('x, y', cls=Function) >>> eq = (Eq(diff(x(t),t), x(t) + y(t) + 17), Eq(diff(y(t),t), -2*x(t) + y(t) + 12)) >>> sol = [Eq(x(t), (C1*sin(sqrt(2)*t) + C2*cos(sqrt(2)*t))*exp(t) - S(5)/3), ... Eq(y(t), (sqrt(2)*C1*cos(sqrt(2)*t) - sqrt(2)*C2*sin(sqrt(2)*t))*exp(t) - S(46)/3)] >>> checksysodesol(eq, sol) (True, [0, 0]) >>> eq = (Eq(diff(x(t),t),x(t)*y(t)**4), Eq(diff(y(t),t),y(t)**3)) >>> sol = [Eq(x(t), C1*exp(-1/(4*(C2 + t)))), Eq(y(t), -sqrt(2)*sqrt(-1/(C2 + t))/2), ... Eq(x(t), C1*exp(-1/(4*(C2 + t)))), Eq(y(t), sqrt(2)*sqrt(-1/(C2 + t))/2)] >>> checksysodesol(eq, sol) (True, [0, 0]) """ def _sympify(eq): return list(map(sympify, eq if iterable(eq) else [eq])) eqs = _sympify(eqs) for i in range(len(eqs)): if isinstance(eqs[i], Equality): eqs[i] = eqs[i].lhs - eqs[i].rhs if func is None: funcs = [] for eq in eqs: derivs = eq.atoms(Derivative) func = set().union(*[d.atoms(AppliedUndef) for d in derivs]) for func_ in func: funcs.append(func_) funcs = list(set(funcs)) if not all(isinstance(func, AppliedUndef) and len(func.args) == 1 for func in funcs)\ and len({func.args for func in funcs})!=1: raise ValueError("func must be a function of one variable, not %s" % func) for sol in sols: if len(sol.atoms(AppliedUndef)) != 1: raise ValueError("solutions should have one function only") if len(funcs) != len({sol.lhs for sol in sols}): raise ValueError("number of solutions provided does not match the number of equations") t = funcs[0].args[0] dictsol = dict() for sol in sols: func = list(sol.atoms(AppliedUndef))[0] if sol.rhs == func: sol = sol.reversed solved = sol.lhs == func and not sol.rhs.has(func) if not solved: rhs = solve(sol, func) if not rhs: raise NotImplementedError else: rhs = sol.rhs dictsol[func] = rhs checkeq = [] for eq in eqs: for func in funcs: eq = sub_func_doit(eq, func, dictsol[func]) ss = simplify(eq) if ss != 0: eq = ss.expand(force=True) else: eq = 0 checkeq.append(eq) if len(set(checkeq)) == 1 and list(set(checkeq))[0] == 0: return (True, checkeq) else: return (False, checkeq) @vectorize(0) def odesimp(eq, func, order, constants, hint): r""" Simplifies ODEs, including trying to solve for ``func`` and running :py:meth:`~sympy.solvers.ode.constantsimp`. It may use knowledge of the type of solution that the hint returns to apply additional simplifications. It also attempts to integrate any :py:class:`~sympy.integrals.Integral`\s in the expression, if the hint is not an ``_Integral`` hint. This function should have no effect on expressions returned by :py:meth:`~sympy.solvers.ode.dsolve`, as :py:meth:`~sympy.solvers.ode.dsolve` already calls :py:meth:`~sympy.solvers.ode.odesimp`, but the individual hint functions do not call :py:meth:`~sympy.solvers.ode.odesimp` (because the :py:meth:`~sympy.solvers.ode.dsolve` wrapper does). Therefore, this function is designed for mainly internal use. Examples ======== >>> from sympy import sin, symbols, dsolve, pprint, Function >>> from sympy.solvers.ode import odesimp >>> x , u2, C1= symbols('x,u2,C1') >>> f = Function('f') >>> eq = dsolve(x*f(x).diff(x) - f(x) - x*sin(f(x)/x), f(x), ... hint='1st_homogeneous_coeff_subs_indep_div_dep_Integral', ... simplify=False) >>> pprint(eq, wrap_line=False) x ---- f(x) / | | / 1 \ | -|u2 + -------| | | /1 \| | | sin|--|| | \ \u2// log(f(x)) = log(C1) + | ---------------- d(u2) | 2 | u2 | / >>> pprint(odesimp(eq, f(x), 1, {C1}, ... hint='1st_homogeneous_coeff_subs_indep_div_dep' ... )) #doctest: +SKIP x --------- = C1 /f(x)\ tan|----| \2*x / """ x = func.args[0] f = func.func C1 = get_numbered_constants(eq, num=1) # First, integrate if the hint allows it. eq = _handle_Integral(eq, func, order, hint) if hint.startswith("nth_linear_euler_eq_nonhomogeneous"): eq = simplify(eq) if not isinstance(eq, Equality): raise TypeError("eq should be an instance of Equality") # Second, clean up the arbitrary constants. # Right now, nth linear hints can put as many as 2*order constants in an # expression. If that number grows with another hint, the third argument # here should be raised accordingly, or constantsimp() rewritten to handle # an arbitrary number of constants. eq = constantsimp(eq, constants) # Lastly, now that we have cleaned up the expression, try solving for func. # When CRootOf is implemented in solve(), we will want to return a CRootOf # every time instead of an Equality. # Get the f(x) on the left if possible. if eq.rhs == func and not eq.lhs.has(func): eq = [Eq(eq.rhs, eq.lhs)] # make sure we are working with lists of solutions in simplified form. if eq.lhs == func and not eq.rhs.has(func): # The solution is already solved eq = [eq] # special simplification of the rhs if hint.startswith("nth_linear_constant_coeff"): # Collect terms to make the solution look nice. # This is also necessary for constantsimp to remove unnecessary # terms from the particular solution from variation of parameters # # Collect is not behaving reliably here. The results for # some linear constant-coefficient equations with repeated # roots do not properly simplify all constants sometimes. # 'collectterms' gives different orders sometimes, and results # differ in collect based on that order. The # sort-reverse trick fixes things, but may fail in the # future. In addition, collect is splitting exponentials with # rational powers for no reason. We have to do a match # to fix this using Wilds. global collectterms try: collectterms.sort(key=default_sort_key) collectterms.reverse() except Exception: pass assert len(eq) == 1 and eq[0].lhs == f(x) sol = eq[0].rhs sol = expand_mul(sol) for i, reroot, imroot in collectterms: sol = collect(sol, x**i*exp(reroot*x)*sin(abs(imroot)*x)) sol = collect(sol, x**i*exp(reroot*x)*cos(imroot*x)) for i, reroot, imroot in collectterms: sol = collect(sol, x**i*exp(reroot*x)) del collectterms # Collect is splitting exponentials with rational powers for # no reason. We call powsimp to fix. sol = powsimp(sol) eq[0] = Eq(f(x), sol) else: # The solution is not solved, so try to solve it try: floats = any(i.is_Float for i in eq.atoms(Number)) eqsol = solve(eq, func, force=True, rational=False if floats else None) if not eqsol: raise NotImplementedError except (NotImplementedError, PolynomialError): eq = [eq] else: def _expand(expr): numer, denom = expr.as_numer_denom() if denom.is_Add: return expr else: return powsimp(expr.expand(), combine='exp', deep=True) # XXX: the rest of odesimp() expects each ``t`` to be in a # specific normal form: rational expression with numerator # expanded, but with combined exponential functions (at # least in this setup all tests pass). eq = [Eq(f(x), _expand(t)) for t in eqsol] # special simplification of the lhs. if hint.startswith("1st_homogeneous_coeff"): for j, eqi in enumerate(eq): newi = logcombine(eqi, force=True) if isinstance(newi.lhs, log) and newi.rhs == 0: newi = Eq(newi.lhs.args[0]/C1, C1) eq[j] = newi # We cleaned up the constants before solving to help the solve engine with # a simpler expression, but the solved expression could have introduced # things like -C1, so rerun constantsimp() one last time before returning. for i, eqi in enumerate(eq): eq[i] = constantsimp(eqi, constants) eq[i] = constant_renumber(eq[i], 'C', 1, 2*order) # If there is only 1 solution, return it; # otherwise return the list of solutions. if len(eq) == 1: eq = eq[0] return eq def checkodesol(ode, sol, func=None, order='auto', solve_for_func=True): r""" Substitutes ``sol`` into ``ode`` and checks that the result is ``0``. This only works when ``func`` is one function, like `f(x)`. ``sol`` can be a single solution or a list of solutions. Each solution may be an :py:class:`~sympy.core.relational.Equality` that the solution satisfies, e.g. ``Eq(f(x), C1), Eq(f(x) + C1, 0)``; or simply an :py:class:`~sympy.core.expr.Expr`, e.g. ``f(x) - C1``. In most cases it will not be necessary to explicitly identify the function, but if the function cannot be inferred from the original equation it can be supplied through the ``func`` argument. If a sequence of solutions is passed, the same sort of container will be used to return the result for each solution. It tries the following methods, in order, until it finds zero equivalence: 1. Substitute the solution for `f` in the original equation. This only works if ``ode`` is solved for `f`. It will attempt to solve it first unless ``solve_for_func == False``. 2. Take `n` derivatives of the solution, where `n` is the order of ``ode``, and check to see if that is equal to the solution. This only works on exact ODEs. 3. Take the 1st, 2nd, ..., `n`\th derivatives of the solution, each time solving for the derivative of `f` of that order (this will always be possible because `f` is a linear operator). Then back substitute each derivative into ``ode`` in reverse order. This function returns a tuple. The first item in the tuple is ``True`` if the substitution results in ``0``, and ``False`` otherwise. The second item in the tuple is what the substitution results in. It should always be ``0`` if the first item is ``True``. Sometimes this function will return ``False`` even when an expression is identically equal to ``0``. This happens when :py:meth:`~sympy.simplify.simplify.simplify` does not reduce the expression to ``0``. If an expression returned by this function vanishes identically, then ``sol`` really is a solution to the ``ode``. If this function seems to hang, it is probably because of a hard simplification. To use this function to test, test the first item of the tuple. Examples ======== >>> from sympy import Eq, Function, checkodesol, symbols >>> x, C1 = symbols('x,C1') >>> f = Function('f') >>> checkodesol(f(x).diff(x), Eq(f(x), C1)) (True, 0) >>> assert checkodesol(f(x).diff(x), C1)[0] >>> assert not checkodesol(f(x).diff(x), x)[0] >>> checkodesol(f(x).diff(x, 2), x**2) (False, 2) """ if not isinstance(ode, Equality): ode = Eq(ode, 0) if func is None: try: _, func = _preprocess(ode.lhs) except ValueError: funcs = [s.atoms(AppliedUndef) for s in ( sol if is_sequence(sol, set) else [sol])] funcs = set().union(*funcs) if len(funcs) != 1: raise ValueError( 'must pass func arg to checkodesol for this case.') func = funcs.pop() if not isinstance(func, AppliedUndef) or len(func.args) != 1: raise ValueError( "func must be a function of one variable, not %s" % func) if is_sequence(sol, set): return type(sol)([checkodesol(ode, i, order=order, solve_for_func=solve_for_func) for i in sol]) if not isinstance(sol, Equality): sol = Eq(func, sol) elif sol.rhs == func: sol = sol.reversed if order == 'auto': order = ode_order(ode, func) solved = sol.lhs == func and not sol.rhs.has(func) if solve_for_func and not solved: rhs = solve(sol, func) if rhs: eqs = [Eq(func, t) for t in rhs] if len(rhs) == 1: eqs = eqs[0] return checkodesol(ode, eqs, order=order, solve_for_func=False) s = True testnum = 0 x = func.args[0] while s: if testnum == 0: # First pass, try substituting a solved solution directly into the # ODE. This has the highest chance of succeeding. ode_diff = ode.lhs - ode.rhs if sol.lhs == func: s = sub_func_doit(ode_diff, func, sol.rhs) else: testnum += 1 continue ss = simplify(s) if ss: # with the new numer_denom in power.py, if we do a simple # expansion then testnum == 0 verifies all solutions. s = ss.expand(force=True) else: s = 0 testnum += 1 elif testnum == 1: # Second pass. If we cannot substitute f, try seeing if the nth # derivative is equal, this will only work for odes that are exact, # by definition. s = simplify( trigsimp(diff(sol.lhs, x, order) - diff(sol.rhs, x, order)) - trigsimp(ode.lhs) + trigsimp(ode.rhs)) # s2 = simplify( # diff(sol.lhs, x, order) - diff(sol.rhs, x, order) - \ # ode.lhs + ode.rhs) testnum += 1 elif testnum == 2: # Third pass. Try solving for df/dx and substituting that into the # ODE. Thanks to Chris Smith for suggesting this method. Many of # the comments below are his, too. # The method: # - Take each of 1..n derivatives of the solution. # - Solve each nth derivative for d^(n)f/dx^(n) # (the differential of that order) # - Back substitute into the ODE in decreasing order # (i.e., n, n-1, ...) # - Check the result for zero equivalence if sol.lhs == func and not sol.rhs.has(func): diffsols = {0: sol.rhs} elif sol.rhs == func and not sol.lhs.has(func): diffsols = {0: sol.lhs} else: diffsols = {} sol = sol.lhs - sol.rhs for i in range(1, order + 1): # Differentiation is a linear operator, so there should always # be 1 solution. Nonetheless, we test just to make sure. # We only need to solve once. After that, we automatically # have the solution to the differential in the order we want. if i == 1: ds = sol.diff(x) try: sdf = solve(ds, func.diff(x, i)) if not sdf: raise NotImplementedError except NotImplementedError: testnum += 1 break else: diffsols[i] = sdf[0] else: # This is what the solution says df/dx should be. diffsols[i] = diffsols[i - 1].diff(x) # Make sure the above didn't fail. if testnum > 2: continue else: # Substitute it into ODE to check for self consistency. lhs, rhs = ode.lhs, ode.rhs for i in range(order, -1, -1): if i == 0 and 0 not in diffsols: # We can only substitute f(x) if the solution was # solved for f(x). break lhs = sub_func_doit(lhs, func.diff(x, i), diffsols[i]) rhs = sub_func_doit(rhs, func.diff(x, i), diffsols[i]) ode_or_bool = Eq(lhs, rhs) ode_or_bool = simplify(ode_or_bool) if isinstance(ode_or_bool, (bool, BooleanAtom)): if ode_or_bool: lhs = rhs = S.Zero else: lhs = ode_or_bool.lhs rhs = ode_or_bool.rhs # No sense in overworking simplify -- just prove that the # numerator goes to zero num = trigsimp((lhs - rhs).as_numer_denom()[0]) # since solutions are obtained using force=True we test # using the same level of assumptions ## replace function with dummy so assumptions will work _func = Dummy('func') num = num.subs(func, _func) ## posify the expression num, reps = posify(num) s = simplify(num).xreplace(reps).xreplace({_func: func}) testnum += 1 else: break if not s: return (True, s) elif s is True: # The code above never was able to change s raise NotImplementedError("Unable to test if " + str(sol) + " is a solution to " + str(ode) + ".") else: return (False, s) def ode_sol_simplicity(sol, func, trysolving=True): r""" Returns an extended integer representing how simple a solution to an ODE is. The following things are considered, in order from most simple to least: - ``sol`` is solved for ``func``. - ``sol`` is not solved for ``func``, but can be if passed to solve (e.g., a solution returned by ``dsolve(ode, func, simplify=False``). - If ``sol`` is not solved for ``func``, then base the result on the length of ``sol``, as computed by ``len(str(sol))``. - If ``sol`` has any unevaluated :py:class:`~sympy.integrals.Integral`\s, this will automatically be considered less simple than any of the above. This function returns an integer such that if solution A is simpler than solution B by above metric, then ``ode_sol_simplicity(sola, func) < ode_sol_simplicity(solb, func)``. Currently, the following are the numbers returned, but if the heuristic is ever improved, this may change. Only the ordering is guaranteed. +----------------------------------------------+-------------------+ | Simplicity | Return | +==============================================+===================+ | ``sol`` solved for ``func`` | ``-2`` | +----------------------------------------------+-------------------+ | ``sol`` not solved for ``func`` but can be | ``-1`` | +----------------------------------------------+-------------------+ | ``sol`` is not solved nor solvable for | ``len(str(sol))`` | | ``func`` | | +----------------------------------------------+-------------------+ | ``sol`` contains an | ``oo`` | | :py:class:`~sympy.integrals.Integral` | | +----------------------------------------------+-------------------+ ``oo`` here means the SymPy infinity, which should compare greater than any integer. If you already know :py:meth:`~sympy.solvers.solvers.solve` cannot solve ``sol``, you can use ``trysolving=False`` to skip that step, which is the only potentially slow step. For example, :py:meth:`~sympy.solvers.ode.dsolve` with the ``simplify=False`` flag should do this. If ``sol`` is a list of solutions, if the worst solution in the list returns ``oo`` it returns that, otherwise it returns ``len(str(sol))``, that is, the length of the string representation of the whole list. Examples ======== This function is designed to be passed to ``min`` as the key argument, such as ``min(listofsolutions, key=lambda i: ode_sol_simplicity(i, f(x)))``. >>> from sympy import symbols, Function, Eq, tan, cos, sqrt, Integral >>> from sympy.solvers.ode import ode_sol_simplicity >>> x, C1, C2 = symbols('x, C1, C2') >>> f = Function('f') >>> ode_sol_simplicity(Eq(f(x), C1*x**2), f(x)) -2 >>> ode_sol_simplicity(Eq(x**2 + f(x), C1), f(x)) -1 >>> ode_sol_simplicity(Eq(f(x), C1*Integral(2*x, x)), f(x)) oo >>> eq1 = Eq(f(x)/tan(f(x)/(2*x)), C1) >>> eq2 = Eq(f(x)/tan(f(x)/(2*x) + f(x)), C2) >>> [ode_sol_simplicity(eq, f(x)) for eq in [eq1, eq2]] [28, 35] >>> min([eq1, eq2], key=lambda i: ode_sol_simplicity(i, f(x))) Eq(f(x)/tan(f(x)/(2*x)), C1) """ # TODO: if two solutions are solved for f(x), we still want to be # able to get the simpler of the two # See the docstring for the coercion rules. We check easier (faster) # things here first, to save time. if iterable(sol): # See if there are Integrals for i in sol: if ode_sol_simplicity(i, func, trysolving=trysolving) == oo: return oo return len(str(sol)) if sol.has(Integral): return oo # Next, try to solve for func. This code will change slightly when CRootOf # is implemented in solve(). Probably a CRootOf solution should fall # somewhere between a normal solution and an unsolvable expression. # First, see if they are already solved if sol.lhs == func and not sol.rhs.has(func) or \ sol.rhs == func and not sol.lhs.has(func): return -2 # We are not so lucky, try solving manually if trysolving: try: sols = solve(sol, func) if not sols: raise NotImplementedError except NotImplementedError: pass else: return -1 # Finally, a naive computation based on the length of the string version # of the expression. This may favor combined fractions because they # will not have duplicate denominators, and may slightly favor expressions # with fewer additions and subtractions, as those are separated by spaces # by the printer. # Additional ideas for simplicity heuristics are welcome, like maybe # checking if a equation has a larger domain, or if constantsimp has # introduced arbitrary constants numbered higher than the order of a # given ODE that sol is a solution of. return len(str(sol)) def _get_constant_subexpressions(expr, Cs): Cs = set(Cs) Ces = [] def _recursive_walk(expr): expr_syms = expr.free_symbols if len(expr_syms) > 0 and expr_syms.issubset(Cs): Ces.append(expr) else: if expr.func == exp: expr = expr.expand(mul=True) if expr.func in (Add, Mul): d = sift(expr.args, lambda i : i.free_symbols.issubset(Cs)) if len(d[True]) > 1: x = expr.func(*d[True]) if not x.is_number: Ces.append(x) elif isinstance(expr, Integral): if expr.free_symbols.issubset(Cs) and \ all(len(x) == 3 for x in expr.limits): Ces.append(expr) for i in expr.args: _recursive_walk(i) return _recursive_walk(expr) return Ces def __remove_linear_redundancies(expr, Cs): cnts = {i: expr.count(i) for i in Cs} Cs = [i for i in Cs if cnts[i] > 0] def _linear(expr): if isinstance(expr, Add): xs = [i for i in Cs if expr.count(i)==cnts[i] \ and 0 == expr.diff(i, 2)] d = {} for x in xs: y = expr.diff(x) if y not in d: d[y]=[] d[y].append(x) for y in d: if len(d[y]) > 1: d[y].sort(key=str) for x in d[y][1:]: expr = expr.subs(x, 0) return expr def _recursive_walk(expr): if len(expr.args) != 0: expr = expr.func(*[_recursive_walk(i) for i in expr.args]) expr = _linear(expr) return expr if isinstance(expr, Equality): lhs, rhs = [_recursive_walk(i) for i in expr.args] f = lambda i: isinstance(i, Number) or i in Cs if isinstance(lhs, Symbol) and lhs in Cs: rhs, lhs = lhs, rhs if lhs.func in (Add, Symbol) and rhs.func in (Add, Symbol): dlhs = sift([lhs] if isinstance(lhs, AtomicExpr) else lhs.args, f) drhs = sift([rhs] if isinstance(rhs, AtomicExpr) else rhs.args, f) for i in [True, False]: for hs in [dlhs, drhs]: if i not in hs: hs[i] = [0] # this calculation can be simplified lhs = Add(*dlhs[False]) - Add(*drhs[False]) rhs = Add(*drhs[True]) - Add(*dlhs[True]) elif lhs.func in (Mul, Symbol) and rhs.func in (Mul, Symbol): dlhs = sift([lhs] if isinstance(lhs, AtomicExpr) else lhs.args, f) if True in dlhs: if False not in dlhs: dlhs[False] = [1] lhs = Mul(*dlhs[False]) rhs = rhs/Mul(*dlhs[True]) return Eq(lhs, rhs) else: return _recursive_walk(expr) @vectorize(0) def constantsimp(expr, constants): r""" Simplifies an expression with arbitrary constants in it. This function is written specifically to work with :py:meth:`~sympy.solvers.ode.dsolve`, and is not intended for general use. Simplification is done by "absorbing" the arbitrary constants into other arbitrary constants, numbers, and symbols that they are not independent of. The symbols must all have the same name with numbers after it, for example, ``C1``, ``C2``, ``C3``. The ``symbolname`` here would be '``C``', the ``startnumber`` would be 1, and the ``endnumber`` would be 3. If the arbitrary constants are independent of the variable ``x``, then the independent symbol would be ``x``. There is no need to specify the dependent function, such as ``f(x)``, because it already has the independent symbol, ``x``, in it. Because terms are "absorbed" into arbitrary constants and because constants are renumbered after simplifying, the arbitrary constants in expr are not necessarily equal to the ones of the same name in the returned result. If two or more arbitrary constants are added, multiplied, or raised to the power of each other, they are first absorbed together into a single arbitrary constant. Then the new constant is combined into other terms if necessary. Absorption of constants is done with limited assistance: 1. terms of :py:class:`~sympy.core.add.Add`\s are collected to try join constants so `e^x (C_1 \cos(x) + C_2 \cos(x))` will simplify to `e^x C_1 \cos(x)`; 2. powers with exponents that are :py:class:`~sympy.core.add.Add`\s are expanded so `e^{C_1 + x}` will be simplified to `C_1 e^x`. Use :py:meth:`~sympy.solvers.ode.constant_renumber` to renumber constants after simplification or else arbitrary numbers on constants may appear, e.g. `C_1 + C_3 x`. In rare cases, a single constant can be "simplified" into two constants. Every differential equation solution should have as many arbitrary constants as the order of the differential equation. The result here will be technically correct, but it may, for example, have `C_1` and `C_2` in an expression, when `C_1` is actually equal to `C_2`. Use your discretion in such situations, and also take advantage of the ability to use hints in :py:meth:`~sympy.solvers.ode.dsolve`. Examples ======== >>> from sympy import symbols >>> from sympy.solvers.ode import constantsimp >>> C1, C2, C3, x, y = symbols('C1, C2, C3, x, y') >>> constantsimp(2*C1*x, {C1, C2, C3}) C1*x >>> constantsimp(C1 + 2 + x, {C1, C2, C3}) C1 + x >>> constantsimp(C1*C2 + 2 + C2 + C3*x, {C1, C2, C3}) C1 + C3*x """ # This function works recursively. The idea is that, for Mul, # Add, Pow, and Function, if the class has a constant in it, then # we can simplify it, which we do by recursing down and # simplifying up. Otherwise, we can skip that part of the # expression. Cs = constants orig_expr = expr constant_subexprs = _get_constant_subexpressions(expr, Cs) for xe in constant_subexprs: xes = list(xe.free_symbols) if not xes: continue if all([expr.count(c) == xe.count(c) for c in xes]): xes.sort(key=str) expr = expr.subs(xe, xes[0]) # try to perform common sub-expression elimination of constant terms try: commons, rexpr = cse(expr) commons.reverse() rexpr = rexpr[0] for s in commons: cs = list(s[1].atoms(Symbol)) if len(cs) == 1 and cs[0] in Cs and \ cs[0] not in rexpr.atoms(Symbol) and \ not any(cs[0] in ex for ex in commons if ex != s): rexpr = rexpr.subs(s[0], cs[0]) else: rexpr = rexpr.subs(*s) expr = rexpr except Exception: pass expr = __remove_linear_redundancies(expr, Cs) def _conditional_term_factoring(expr): new_expr = terms_gcd(expr, clear=False, deep=True, expand=False) # we do not want to factor exponentials, so handle this separately if new_expr.is_Mul: infac = False asfac = False for m in new_expr.args: if isinstance(m, exp): asfac = True elif m.is_Add: infac = any(isinstance(fi, exp) for t in m.args for fi in Mul.make_args(t)) if asfac and infac: new_expr = expr break return new_expr expr = _conditional_term_factoring(expr) # call recursively if more simplification is possible if orig_expr != expr: return constantsimp(expr, Cs) return expr def constant_renumber(expr, symbolname, startnumber, endnumber): r""" Renumber arbitrary constants in ``expr`` to have numbers 1 through `N` where `N` is ``endnumber - startnumber + 1`` at most. In the process, this reorders expression terms in a standard way. This is a simple function that goes through and renumbers any :py:class:`~sympy.core.symbol.Symbol` with a name in the form ``symbolname + num`` where ``num`` is in the range from ``startnumber`` to ``endnumber``. Symbols are renumbered based on ``.sort_key()``, so they should be numbered roughly in the order that they appear in the final, printed expression. Note that this ordering is based in part on hashes, so it can produce different results on different machines. The structure of this function is very similar to that of :py:meth:`~sympy.solvers.ode.constantsimp`. Examples ======== >>> from sympy import symbols, Eq, pprint >>> from sympy.solvers.ode import constant_renumber >>> x, C0, C1, C2, C3, C4 = symbols('x,C:5') Only constants in the given range (inclusive) are renumbered; the renumbering always starts from 1: >>> constant_renumber(C1 + C3 + C4, 'C', 1, 3) C1 + C2 + C4 >>> constant_renumber(C0 + C1 + C3 + C4, 'C', 2, 4) C0 + 2*C1 + C2 >>> constant_renumber(C0 + 2*C1 + C2, 'C', 0, 1) C1 + 3*C2 >>> pprint(C2 + C1*x + C3*x**2) 2 C1*x + C2 + C3*x >>> pprint(constant_renumber(C2 + C1*x + C3*x**2, 'C', 1, 3)) 2 C1 + C2*x + C3*x """ if type(expr) in (set, list, tuple): return type(expr)( [constant_renumber(i, symbolname=symbolname, startnumber=startnumber, endnumber=endnumber) for i in expr] ) global newstartnumber newstartnumber = 1 constants_found = [None]*(endnumber + 2) constantsymbols = [Symbol( symbolname + "%d" % t) for t in range(startnumber, endnumber + 1)] # make a mapping to send all constantsymbols to S.One and use # that to make sure that term ordering is not dependent on # the indexed value of C C_1 = [(ci, S.One) for ci in constantsymbols] sort_key=lambda arg: default_sort_key(arg.subs(C_1)) def _constant_renumber(expr): r""" We need to have an internal recursive function so that newstartnumber maintains its values throughout recursive calls. """ global newstartnumber if isinstance(expr, Equality): return Eq( _constant_renumber(expr.lhs), _constant_renumber(expr.rhs)) if type(expr) not in (Mul, Add, Pow) and not expr.is_Function and \ not expr.has(*constantsymbols): # Base case, as above. Hope there aren't constants inside # of some other class, because they won't be renumbered. return expr elif expr.is_Piecewise: return expr elif expr in constantsymbols: if expr not in constants_found: constants_found[newstartnumber] = expr newstartnumber += 1 return expr elif expr.is_Function or expr.is_Pow or isinstance(expr, Tuple): return expr.func( *[_constant_renumber(x) for x in expr.args]) else: sortedargs = list(expr.args) sortedargs.sort(key=sort_key) return expr.func(*[_constant_renumber(x) for x in sortedargs]) expr = _constant_renumber(expr) # Renumbering happens here newconsts = symbols('C1:%d' % newstartnumber) expr = expr.subs(zip(constants_found[1:], newconsts), simultaneous=True) return expr def _handle_Integral(expr, func, order, hint): r""" Converts a solution with Integrals in it into an actual solution. For most hints, this simply runs ``expr.doit()``. """ global y x = func.args[0] f = func.func if hint == "1st_exact": sol = (expr.doit()).subs(y, f(x)) del y elif hint == "1st_exact_Integral": sol = Eq(Subs(expr.lhs, y, f(x)), expr.rhs) del y elif hint == "nth_linear_constant_coeff_homogeneous": sol = expr elif not hint.endswith("_Integral"): sol = expr.doit() else: sol = expr return sol # FIXME: replace the general solution in the docstring with # dsolve(equation, hint='1st_exact_Integral'). You will need to be able # to have assumptions on P and Q that dP/dy = dQ/dx. def ode_1st_exact(eq, func, order, match): r""" Solves 1st order exact ordinary differential equations. A 1st order differential equation is called exact if it is the total differential of a function. That is, the differential equation .. math:: P(x, y) \,\partial{}x + Q(x, y) \,\partial{}y = 0 is exact if there is some function `F(x, y)` such that `P(x, y) = \partial{}F/\partial{}x` and `Q(x, y) = \partial{}F/\partial{}y`. It can be shown that a necessary and sufficient condition for a first order ODE to be exact is that `\partial{}P/\partial{}y = \partial{}Q/\partial{}x`. Then, the solution will be as given below:: >>> from sympy import Function, Eq, Integral, symbols, pprint >>> x, y, t, x0, y0, C1= symbols('x,y,t,x0,y0,C1') >>> P, Q, F= map(Function, ['P', 'Q', 'F']) >>> pprint(Eq(Eq(F(x, y), Integral(P(t, y), (t, x0, x)) + ... Integral(Q(x0, t), (t, y0, y))), C1)) x y / / | | F(x, y) = | P(t, y) dt + | Q(x0, t) dt = C1 | | / / x0 y0 Where the first partials of `P` and `Q` exist and are continuous in a simply connected region. A note: SymPy currently has no way to represent inert substitution on an expression, so the hint ``1st_exact_Integral`` will return an integral with `dy`. This is supposed to represent the function that you are solving for. Examples ======== >>> from sympy import Function, dsolve, cos, sin >>> from sympy.abc import x >>> f = Function('f') >>> dsolve(cos(f(x)) - (x*sin(f(x)) - f(x)**2)*f(x).diff(x), ... f(x), hint='1st_exact') Eq(x*cos(f(x)) + f(x)**3/3, C1) References ========== - https://en.wikipedia.org/wiki/Exact_differential_equation - M. Tenenbaum & H. Pollard, "Ordinary Differential Equations", Dover 1963, pp. 73 # indirect doctest """ x = func.args[0] f = func.func r = match # d+e*diff(f(x),x) e = r[r['e']] d = r[r['d']] global y # This is the only way to pass dummy y to _handle_Integral y = r['y'] C1 = get_numbered_constants(eq, num=1) # Refer Joel Moses, "Symbolic Integration - The Stormy Decade", # Communications of the ACM, Volume 14, Number 8, August 1971, pp. 558 # which gives the method to solve an exact differential equation. sol = Integral(d, x) + Integral((e - (Integral(d, x).diff(y))), y) return Eq(sol, C1) def ode_1st_homogeneous_coeff_best(eq, func, order, match): r""" Returns the best solution to an ODE from the two hints ``1st_homogeneous_coeff_subs_dep_div_indep`` and ``1st_homogeneous_coeff_subs_indep_div_dep``. This is as determined by :py:meth:`~sympy.solvers.ode.ode_sol_simplicity`. See the :py:meth:`~sympy.solvers.ode.ode_1st_homogeneous_coeff_subs_indep_div_dep` and :py:meth:`~sympy.solvers.ode.ode_1st_homogeneous_coeff_subs_dep_div_indep` docstrings for more information on these hints. Note that there is no ``ode_1st_homogeneous_coeff_best_Integral`` hint. Examples ======== >>> from sympy import Function, dsolve, pprint >>> from sympy.abc import x >>> f = Function('f') >>> pprint(dsolve(2*x*f(x) + (x**2 + f(x)**2)*f(x).diff(x), f(x), ... hint='1st_homogeneous_coeff_best', simplify=False)) / 2 \ | 3*x | log|----- + 1| | 2 | \f (x) / log(f(x)) = log(C1) - -------------- 3 References ========== - https://en.wikipedia.org/wiki/Homogeneous_differential_equation - M. Tenenbaum & H. Pollard, "Ordinary Differential Equations", Dover 1963, pp. 59 # indirect doctest """ # There are two substitutions that solve the equation, u1=y/x and u2=x/y # They produce different integrals, so try them both and see which # one is easier. sol1 = ode_1st_homogeneous_coeff_subs_indep_div_dep(eq, func, order, match) sol2 = ode_1st_homogeneous_coeff_subs_dep_div_indep(eq, func, order, match) simplify = match.get('simplify', True) if simplify: # why is odesimp called here? Should it be at the usual spot? constants = sol1.free_symbols.difference(eq.free_symbols) sol1 = odesimp( sol1, func, order, constants, "1st_homogeneous_coeff_subs_indep_div_dep") constants = sol2.free_symbols.difference(eq.free_symbols) sol2 = odesimp( sol2, func, order, constants, "1st_homogeneous_coeff_subs_dep_div_indep") return min([sol1, sol2], key=lambda x: ode_sol_simplicity(x, func, trysolving=not simplify)) def ode_1st_homogeneous_coeff_subs_dep_div_indep(eq, func, order, match): r""" Solves a 1st order differential equation with homogeneous coefficients using the substitution `u_1 = \frac{\text{<dependent variable>}}{\text{<independent variable>}}`. This is a differential equation .. math:: P(x, y) + Q(x, y) dy/dx = 0 such that `P` and `Q` are homogeneous and of the same order. A function `F(x, y)` is homogeneous of order `n` if `F(x t, y t) = t^n F(x, y)`. Equivalently, `F(x, y)` can be rewritten as `G(y/x)` or `H(x/y)`. See also the docstring of :py:meth:`~sympy.solvers.ode.homogeneous_order`. If the coefficients `P` and `Q` in the differential equation above are homogeneous functions of the same order, then it can be shown that the substitution `y = u_1 x` (i.e. `u_1 = y/x`) will turn the differential equation into an equation separable in the variables `x` and `u`. If `h(u_1)` is the function that results from making the substitution `u_1 = f(x)/x` on `P(x, f(x))` and `g(u_2)` is the function that results from the substitution on `Q(x, f(x))` in the differential equation `P(x, f(x)) + Q(x, f(x)) f'(x) = 0`, then the general solution is:: >>> from sympy import Function, dsolve, pprint >>> from sympy.abc import x >>> f, g, h = map(Function, ['f', 'g', 'h']) >>> genform = g(f(x)/x) + h(f(x)/x)*f(x).diff(x) >>> pprint(genform) /f(x)\ /f(x)\ d g|----| + h|----|*--(f(x)) \ x / \ x / dx >>> pprint(dsolve(genform, f(x), ... hint='1st_homogeneous_coeff_subs_dep_div_indep_Integral')) f(x) ---- x / | | -h(u1) log(x) = C1 + | ---------------- d(u1) | u1*h(u1) + g(u1) | / Where `u_1 h(u_1) + g(u_1) \ne 0` and `x \ne 0`. See also the docstrings of :py:meth:`~sympy.solvers.ode.ode_1st_homogeneous_coeff_best` and :py:meth:`~sympy.solvers.ode.ode_1st_homogeneous_coeff_subs_indep_div_dep`. Examples ======== >>> from sympy import Function, dsolve >>> from sympy.abc import x >>> f = Function('f') >>> pprint(dsolve(2*x*f(x) + (x**2 + f(x)**2)*f(x).diff(x), f(x), ... hint='1st_homogeneous_coeff_subs_dep_div_indep', simplify=False)) / 3 \ |3*f(x) f (x)| log|------ + -----| | x 3 | \ x / log(x) = log(C1) - ------------------- 3 References ========== - https://en.wikipedia.org/wiki/Homogeneous_differential_equation - M. Tenenbaum & H. Pollard, "Ordinary Differential Equations", Dover 1963, pp. 59 # indirect doctest """ x = func.args[0] f = func.func u = Dummy('u') u1 = Dummy('u1') # u1 == f(x)/x r = match # d+e*diff(f(x),x) C1 = get_numbered_constants(eq, num=1) xarg = match.get('xarg', 0) yarg = match.get('yarg', 0) int = Integral( (-r[r['e']]/(r[r['d']] + u1*r[r['e']])).subs({x: 1, r['y']: u1}), (u1, None, f(x)/x)) sol = logcombine(Eq(log(x), int + log(C1)), force=True) sol = sol.subs(f(x), u).subs(((u, u - yarg), (x, x - xarg), (u, f(x)))) return sol def ode_1st_homogeneous_coeff_subs_indep_div_dep(eq, func, order, match): r""" Solves a 1st order differential equation with homogeneous coefficients using the substitution `u_2 = \frac{\text{<independent variable>}}{\text{<dependent variable>}}`. This is a differential equation .. math:: P(x, y) + Q(x, y) dy/dx = 0 such that `P` and `Q` are homogeneous and of the same order. A function `F(x, y)` is homogeneous of order `n` if `F(x t, y t) = t^n F(x, y)`. Equivalently, `F(x, y)` can be rewritten as `G(y/x)` or `H(x/y)`. See also the docstring of :py:meth:`~sympy.solvers.ode.homogeneous_order`. If the coefficients `P` and `Q` in the differential equation above are homogeneous functions of the same order, then it can be shown that the substitution `x = u_2 y` (i.e. `u_2 = x/y`) will turn the differential equation into an equation separable in the variables `y` and `u_2`. If `h(u_2)` is the function that results from making the substitution `u_2 = x/f(x)` on `P(x, f(x))` and `g(u_2)` is the function that results from the substitution on `Q(x, f(x))` in the differential equation `P(x, f(x)) + Q(x, f(x)) f'(x) = 0`, then the general solution is: >>> from sympy import Function, dsolve, pprint >>> from sympy.abc import x >>> f, g, h = map(Function, ['f', 'g', 'h']) >>> genform = g(x/f(x)) + h(x/f(x))*f(x).diff(x) >>> pprint(genform) / x \ / x \ d g|----| + h|----|*--(f(x)) \f(x)/ \f(x)/ dx >>> pprint(dsolve(genform, f(x), ... hint='1st_homogeneous_coeff_subs_indep_div_dep_Integral')) x ---- f(x) / | | -g(u2) | ---------------- d(u2) | u2*g(u2) + h(u2) | / <BLANKLINE> f(x) = C1*e Where `u_2 g(u_2) + h(u_2) \ne 0` and `f(x) \ne 0`. See also the docstrings of :py:meth:`~sympy.solvers.ode.ode_1st_homogeneous_coeff_best` and :py:meth:`~sympy.solvers.ode.ode_1st_homogeneous_coeff_subs_dep_div_indep`. Examples ======== >>> from sympy import Function, pprint, dsolve >>> from sympy.abc import x >>> f = Function('f') >>> pprint(dsolve(2*x*f(x) + (x**2 + f(x)**2)*f(x).diff(x), f(x), ... hint='1st_homogeneous_coeff_subs_indep_div_dep', ... simplify=False)) / 2 \ | 3*x | log|----- + 1| | 2 | \f (x) / log(f(x)) = log(C1) - -------------- 3 References ========== - https://en.wikipedia.org/wiki/Homogeneous_differential_equation - M. Tenenbaum & H. Pollard, "Ordinary Differential Equations", Dover 1963, pp. 59 # indirect doctest """ x = func.args[0] f = func.func u = Dummy('u') u2 = Dummy('u2') # u2 == x/f(x) r = match # d+e*diff(f(x),x) C1 = get_numbered_constants(eq, num=1) xarg = match.get('xarg', 0) # If xarg present take xarg, else zero yarg = match.get('yarg', 0) # If yarg present take yarg, else zero int = Integral( simplify( (-r[r['d']]/(r[r['e']] + u2*r[r['d']])).subs({x: u2, r['y']: 1})), (u2, None, x/f(x))) sol = logcombine(Eq(log(f(x)), int + log(C1)), force=True) sol = sol.subs(f(x), u).subs(((u, u - yarg), (x, x - xarg), (u, f(x)))) return sol # XXX: Should this function maybe go somewhere else? def homogeneous_order(eq, *symbols): r""" Returns the order `n` if `g` is homogeneous and ``None`` if it is not homogeneous. Determines if a function is homogeneous and if so of what order. A function `f(x, y, \cdots)` is homogeneous of order `n` if `f(t x, t y, \cdots) = t^n f(x, y, \cdots)`. If the function is of two variables, `F(x, y)`, then `f` being homogeneous of any order is equivalent to being able to rewrite `F(x, y)` as `G(x/y)` or `H(y/x)`. This fact is used to solve 1st order ordinary differential equations whose coefficients are homogeneous of the same order (see the docstrings of :py:meth:`~solvers.ode.ode_1st_homogeneous_coeff_subs_dep_div_indep` and :py:meth:`~solvers.ode.ode_1st_homogeneous_coeff_subs_indep_div_dep`). Symbols can be functions, but every argument of the function must be a symbol, and the arguments of the function that appear in the expression must match those given in the list of symbols. If a declared function appears with different arguments than given in the list of symbols, ``None`` is returned. Examples ======== >>> from sympy import Function, homogeneous_order, sqrt >>> from sympy.abc import x, y >>> f = Function('f') >>> homogeneous_order(f(x), f(x)) is None True >>> homogeneous_order(f(x,y), f(y, x), x, y) is None True >>> homogeneous_order(f(x), f(x), x) 1 >>> homogeneous_order(x**2*f(x)/sqrt(x**2+f(x)**2), x, f(x)) 2 >>> homogeneous_order(x**2+f(x), x, f(x)) is None True """ if not symbols: raise ValueError("homogeneous_order: no symbols were given.") symset = set(symbols) eq = sympify(eq) # The following are not supported if eq.has(Order, Derivative): return None # These are all constants if (eq.is_Number or eq.is_NumberSymbol or eq.is_number ): return S.Zero # Replace all functions with dummy variables dum = numbered_symbols(prefix='d', cls=Dummy) newsyms = set() for i in [j for j in symset if getattr(j, 'is_Function')]: iargs = set(i.args) if iargs.difference(symset): return None else: dummyvar = next(dum) eq = eq.subs(i, dummyvar) symset.remove(i) newsyms.add(dummyvar) symset.update(newsyms) if not eq.free_symbols & symset: return None # assuming order of a nested function can only be equal to zero if isinstance(eq, Function): return None if homogeneous_order( eq.args[0], *tuple(symset)) != 0 else S.Zero # make the replacement of x with x*t and see if t can be factored out t = Dummy('t', positive=True) # It is sufficient that t > 0 eqs = separatevars(eq.subs([(i, t*i) for i in symset]), [t], dict=True)[t] if eqs is S.One: return S.Zero # there was no term with only t i, d = eqs.as_independent(t, as_Add=False) b, e = d.as_base_exp() if b == t: return e def ode_1st_linear(eq, func, order, match): r""" Solves 1st order linear differential equations. These are differential equations of the form .. math:: dy/dx + P(x) y = Q(x)\text{.} These kinds of differential equations can be solved in a general way. The integrating factor `e^{\int P(x) \,dx}` will turn the equation into a separable equation. The general solution is:: >>> from sympy import Function, dsolve, Eq, pprint, diff, sin >>> from sympy.abc import x >>> f, P, Q = map(Function, ['f', 'P', 'Q']) >>> genform = Eq(f(x).diff(x) + P(x)*f(x), Q(x)) >>> pprint(genform) d P(x)*f(x) + --(f(x)) = Q(x) dx >>> pprint(dsolve(genform, f(x), hint='1st_linear_Integral')) / / \ | | | | | / | / | | | | | | | | P(x) dx | - | P(x) dx | | | | | | | / | / f(x) = |C1 + | Q(x)*e dx|*e | | | \ / / Examples ======== >>> f = Function('f') >>> pprint(dsolve(Eq(x*diff(f(x), x) - f(x), x**2*sin(x)), ... f(x), '1st_linear')) f(x) = x*(C1 - cos(x)) References ========== - https://en.wikipedia.org/wiki/Linear_differential_equation#First_order_equation - M. Tenenbaum & H. Pollard, "Ordinary Differential Equations", Dover 1963, pp. 92 # indirect doctest """ x = func.args[0] f = func.func r = match # a*diff(f(x),x) + b*f(x) + c C1 = get_numbered_constants(eq, num=1) t = exp(Integral(r[r['b']]/r[r['a']], x)) tt = Integral(t*(-r[r['c']]/r[r['a']]), x) f = match.get('u', f(x)) # take almost-linear u if present, else f(x) return Eq(f, (tt + C1)/t) def ode_Bernoulli(eq, func, order, match): r""" Solves Bernoulli differential equations. These are equations of the form .. math:: dy/dx + P(x) y = Q(x) y^n\text{, }n \ne 1`\text{.} The substitution `w = 1/y^{1-n}` will transform an equation of this form into one that is linear (see the docstring of :py:meth:`~sympy.solvers.ode.ode_1st_linear`). The general solution is:: >>> from sympy import Function, dsolve, Eq, pprint >>> from sympy.abc import x, n >>> f, P, Q = map(Function, ['f', 'P', 'Q']) >>> genform = Eq(f(x).diff(x) + P(x)*f(x), Q(x)*f(x)**n) >>> pprint(genform) d n P(x)*f(x) + --(f(x)) = Q(x)*f (x) dx >>> pprint(dsolve(genform, f(x), hint='Bernoulli_Integral')) #doctest: +SKIP 1 ---- 1 - n // / \ \ || | | | || | / | / | || | | | | | || | (1 - n)* | P(x) dx | (-1 + n)* | P(x) dx| || | | | | | || | / | / | f(x) = ||C1 + (-1 + n)* | -Q(x)*e dx|*e | || | | | \\ / / / Note that the equation is separable when `n = 1` (see the docstring of :py:meth:`~sympy.solvers.ode.ode_separable`). >>> pprint(dsolve(Eq(f(x).diff(x) + P(x)*f(x), Q(x)*f(x)), f(x), ... hint='separable_Integral')) f(x) / | / | 1 | | - dy = C1 + | (-P(x) + Q(x)) dx | y | | / / Examples ======== >>> from sympy import Function, dsolve, Eq, pprint, log >>> from sympy.abc import x >>> f = Function('f') >>> pprint(dsolve(Eq(x*f(x).diff(x) + f(x), log(x)*f(x)**2), ... f(x), hint='Bernoulli')) 1 f(x) = ------------------- / log(x) 1\ x*|C1 + ------ + -| \ x x/ References ========== - https://en.wikipedia.org/wiki/Bernoulli_differential_equation - M. Tenenbaum & H. Pollard, "Ordinary Differential Equations", Dover 1963, pp. 95 # indirect doctest """ x = func.args[0] f = func.func r = match # a*diff(f(x),x) + b*f(x) + c*f(x)**n, n != 1 C1 = get_numbered_constants(eq, num=1) t = exp((1 - r[r['n']])*Integral(r[r['b']]/r[r['a']], x)) tt = (r[r['n']] - 1)*Integral(t*r[r['c']]/r[r['a']], x) return Eq(f(x), ((tt + C1)/t)**(1/(1 - r[r['n']]))) def ode_Riccati_special_minus2(eq, func, order, match): r""" The general Riccati equation has the form .. math:: dy/dx = f(x) y^2 + g(x) y + h(x)\text{.} While it does not have a general solution [1], the "special" form, `dy/dx = a y^2 - b x^c`, does have solutions in many cases [2]. This routine returns a solution for `a(dy/dx) = b y^2 + c y/x + d/x^2` that is obtained by using a suitable change of variables to reduce it to the special form and is valid when neither `a` nor `b` are zero and either `c` or `d` is zero. >>> from sympy.abc import x, y, a, b, c, d >>> from sympy.solvers.ode import dsolve, checkodesol >>> from sympy import pprint, Function >>> f = Function('f') >>> y = f(x) >>> genform = a*y.diff(x) - (b*y**2 + c*y/x + d/x**2) >>> sol = dsolve(genform, y) >>> pprint(sol, wrap_line=False) / / __________________ \\ | __________________ | / 2 || | / 2 | \/ 4*b*d - (a + c) *log(x)|| -|a + c - \/ 4*b*d - (a + c) *tan|C1 + ----------------------------|| \ \ 2*a // f(x) = ------------------------------------------------------------------------ 2*b*x >>> checkodesol(genform, sol, order=1)[0] True References ========== 1. http://www.maplesoft.com/support/help/Maple/view.aspx?path=odeadvisor/Riccati 2. http://eqworld.ipmnet.ru/en/solutions/ode/ode0106.pdf - http://eqworld.ipmnet.ru/en/solutions/ode/ode0123.pdf """ x = func.args[0] f = func.func r = match # a2*diff(f(x),x) + b2*f(x) + c2*f(x)/x + d2/x**2 a2, b2, c2, d2 = [r[r[s]] for s in 'a2 b2 c2 d2'.split()] C1 = get_numbered_constants(eq, num=1) mu = sqrt(4*d2*b2 - (a2 - c2)**2) return Eq(f(x), (a2 - c2 - mu*tan(mu/(2*a2)*log(x) + C1))/(2*b2*x)) def ode_Liouville(eq, func, order, match): r""" Solves 2nd order Liouville differential equations. The general form of a Liouville ODE is .. math:: \frac{d^2 y}{dx^2} + g(y) \left(\! \frac{dy}{dx}\!\right)^2 + h(x) \frac{dy}{dx}\text{.} The general solution is: >>> from sympy import Function, dsolve, Eq, pprint, diff >>> from sympy.abc import x >>> f, g, h = map(Function, ['f', 'g', 'h']) >>> genform = Eq(diff(f(x),x,x) + g(f(x))*diff(f(x),x)**2 + ... h(x)*diff(f(x),x), 0) >>> pprint(genform) 2 2 /d \ d d g(f(x))*|--(f(x))| + h(x)*--(f(x)) + ---(f(x)) = 0 \dx / dx 2 dx >>> pprint(dsolve(genform, f(x), hint='Liouville_Integral')) f(x) / / | | | / | / | | | | | - | h(x) dx | | g(y) dy | | | | | / | / C1 + C2* | e dx + | e dy = 0 | | / / Examples ======== >>> from sympy import Function, dsolve, Eq, pprint >>> from sympy.abc import x >>> f = Function('f') >>> pprint(dsolve(diff(f(x), x, x) + diff(f(x), x)**2/f(x) + ... diff(f(x), x)/x, f(x), hint='Liouville')) ________________ ________________ [f(x) = -\/ C1 + C2*log(x) , f(x) = \/ C1 + C2*log(x) ] References ========== - Goldstein and Braun, "Advanced Methods for the Solution of Differential Equations", pp. 98 - http://www.maplesoft.com/support/help/Maple/view.aspx?path=odeadvisor/Liouville # indirect doctest """ # Liouville ODE: # f(x).diff(x, 2) + g(f(x))*(f(x).diff(x, 2))**2 + h(x)*f(x).diff(x) # See Goldstein and Braun, "Advanced Methods for the Solution of # Differential Equations", pg. 98, as well as # http://www.maplesoft.com/support/help/view.aspx?path=odeadvisor/Liouville x = func.args[0] f = func.func r = match # f(x).diff(x, 2) + g*f(x).diff(x)**2 + h*f(x).diff(x) y = r['y'] C1, C2 = get_numbered_constants(eq, num=2) int = Integral(exp(Integral(r['g'], y)), (y, None, f(x))) sol = Eq(int + C1*Integral(exp(-Integral(r['h'], x)), x) + C2, 0) return sol def ode_2nd_power_series_ordinary(eq, func, order, match): r""" Gives a power series solution to a second order homogeneous differential equation with polynomial coefficients at an ordinary point. A homogenous differential equation is of the form .. math :: P(x)\frac{d^2y}{dx^2} + Q(x)\frac{dy}{dx} + R(x) = 0 For simplicity it is assumed that `P(x)`, `Q(x)` and `R(x)` are polynomials, it is sufficient that `\frac{Q(x)}{P(x)}` and `\frac{R(x)}{P(x)}` exists at `x_{0}`. A recurrence relation is obtained by substituting `y` as `\sum_{n=0}^\infty a_{n}x^{n}`, in the differential equation, and equating the nth term. Using this relation various terms can be generated. Examples ======== >>> from sympy import dsolve, Function, pprint >>> from sympy.abc import x, y >>> f = Function("f") >>> eq = f(x).diff(x, 2) + f(x) >>> pprint(dsolve(eq, hint='2nd_power_series_ordinary')) / 4 2 \ / 2 \ |x x | | x | / 6\ f(x) = C2*|-- - -- + 1| + C1*x*|- -- + 1| + O\x / \24 2 / \ 6 / References ========== - http://tutorial.math.lamar.edu/Classes/DE/SeriesSolutions.aspx - George E. Simmons, "Differential Equations with Applications and Historical Notes", p.p 176 - 184 """ x = func.args[0] f = func.func C0, C1 = get_numbered_constants(eq, num=2) n = Dummy("n", integer=True) s = Wild("s") k = Wild("k", exclude=[x]) x0 = match.get('x0') terms = match.get('terms', 5) p = match[match['a3']] q = match[match['b3']] r = match[match['c3']] seriesdict = {} recurr = Function("r") # Generating the recurrence relation which works this way: # for the second order term the summation begins at n = 2. The coefficients # p is multiplied with an*(n - 1)*(n - 2)*x**n-2 and a substitution is made such that # the exponent of x becomes n. # For example, if p is x, then the second degree recurrence term is # an*(n - 1)*(n - 2)*x**n-1, substituting (n - 1) as n, it transforms to # an+1*n*(n - 1)*x**n. # A similar process is done with the first order and zeroth order term. coefflist = [(recurr(n), r), (n*recurr(n), q), (n*(n - 1)*recurr(n), p)] for index, coeff in enumerate(coefflist): if coeff[1]: f2 = powsimp(expand((coeff[1]*(x - x0)**(n - index)).subs(x, x + x0))) if f2.is_Add: addargs = f2.args else: addargs = [f2] for arg in addargs: powm = arg.match(s*x**k) term = coeff[0]*powm[s] if not powm[k].is_Symbol: term = term.subs(n, n - powm[k].as_independent(n)[0]) startind = powm[k].subs(n, index) # Seeing if the startterm can be reduced further. # If it vanishes for n lesser than startind, it is # equal to summation from n. if startind: for i in reversed(range(startind)): if not term.subs(n, i): seriesdict[term] = i else: seriesdict[term] = i + 1 break else: seriesdict[term] = S(0) # Stripping of terms so that the sum starts with the same number. teq = S(0) suminit = seriesdict.values() rkeys = seriesdict.keys() req = Add(*rkeys) if any(suminit): maxval = max(suminit) for term in seriesdict: val = seriesdict[term] if val != maxval: for i in range(val, maxval): teq += term.subs(n, val) finaldict = {} if teq: fargs = teq.atoms(AppliedUndef) if len(fargs) == 1: finaldict[fargs.pop()] = 0 else: maxf = max(fargs, key = lambda x: x.args[0]) sol = solve(teq, maxf) if isinstance(sol, list): sol = sol[0] finaldict[maxf] = sol # Finding the recurrence relation in terms of the largest term. fargs = req.atoms(AppliedUndef) maxf = max(fargs, key = lambda x: x.args[0]) minf = min(fargs, key = lambda x: x.args[0]) if minf.args[0].is_Symbol: startiter = 0 else: startiter = -minf.args[0].as_independent(n)[0] lhs = maxf rhs = solve(req, maxf) if isinstance(rhs, list): rhs = rhs[0] # Checking how many values are already present tcounter = len([t for t in finaldict.values() if t]) for _ in range(tcounter, terms - 3): # Assuming c0 and c1 to be arbitrary check = rhs.subs(n, startiter) nlhs = lhs.subs(n, startiter) nrhs = check.subs(finaldict) finaldict[nlhs] = nrhs startiter += 1 # Post processing series = C0 + C1*(x - x0) for term in finaldict: if finaldict[term]: fact = term.args[0] series += (finaldict[term].subs([(recurr(0), C0), (recurr(1), C1)])*( x - x0)**fact) series = collect(expand_mul(series), [C0, C1]) + Order(x**terms) return Eq(f(x), series) def ode_2nd_power_series_regular(eq, func, order, match): r""" Gives a power series solution to a second order homogeneous differential equation with polynomial coefficients at a regular point. A second order homogenous differential equation is of the form .. math :: P(x)\frac{d^2y}{dx^2} + Q(x)\frac{dy}{dx} + R(x) = 0 A point is said to regular singular at `x0` if `x - x0\frac{Q(x)}{P(x)}` and `(x - x0)^{2}\frac{R(x)}{P(x)}` are analytic at `x0`. For simplicity `P(x)`, `Q(x)` and `R(x)` are assumed to be polynomials. The algorithm for finding the power series solutions is: 1. Try expressing `(x - x0)P(x)` and `((x - x0)^{2})Q(x)` as power series solutions about x0. Find `p0` and `q0` which are the constants of the power series expansions. 2. Solve the indicial equation `f(m) = m(m - 1) + m*p0 + q0`, to obtain the roots `m1` and `m2` of the indicial equation. 3. If `m1 - m2` is a non integer there exists two series solutions. If `m1 = m2`, there exists only one solution. If `m1 - m2` is an integer, then the existence of one solution is confirmed. The other solution may or may not exist. The power series solution is of the form `x^{m}\sum_{n=0}^\infty a_{n}x^{n}`. The coefficients are determined by the following recurrence relation. `a_{n} = -\frac{\sum_{k=0}^{n-1} q_{n-k} + (m + k)p_{n-k}}{f(m + n)}`. For the case in which `m1 - m2` is an integer, it can be seen from the recurrence relation that for the lower root `m`, when `n` equals the difference of both the roots, the denominator becomes zero. So if the numerator is not equal to zero, a second series solution exists. Examples ======== >>> from sympy import dsolve, Function, pprint >>> from sympy.abc import x, y >>> f = Function("f") >>> eq = x*(f(x).diff(x, 2)) + 2*(f(x).diff(x)) + x*f(x) >>> pprint(dsolve(eq)) / 6 4 2 \ | x x x | / 4 2 \ C1*|- --- + -- - -- + 1| | x x | \ 720 24 2 / / 6\ f(x) = C2*|--- - -- + 1| + ------------------------ + O\x / \120 6 / x References ========== - George E. Simmons, "Differential Equations with Applications and Historical Notes", p.p 176 - 184 """ x = func.args[0] f = func.func C0, C1 = get_numbered_constants(eq, num=2) n = Dummy("n") m = Dummy("m") # for solving the indicial equation s = Wild("s") k = Wild("k", exclude=[x]) x0 = match.get('x0') terms = match.get('terms', 5) p = match['p'] q = match['q'] # Generating the indicial equation indicial = [] for term in [p, q]: if not term.has(x): indicial.append(term) else: term = series(term, n=1, x0=x0) if isinstance(term, Order): indicial.append(S(0)) else: for arg in term.args: if not arg.has(x): indicial.append(arg) break p0, q0 = indicial sollist = solve(m*(m - 1) + m*p0 + q0, m) if sollist and isinstance(sollist, list) and all( [sol.is_real for sol in sollist]): serdict1 = {} serdict2 = {} if len(sollist) == 1: # Only one series solution exists in this case. m1 = m2 = sollist.pop() if terms-m1-1 <= 0: return Eq(f(x), Order(terms)) serdict1 = _frobenius(terms-m1-1, m1, p0, q0, p, q, x0, x, C0) else: m1 = sollist[0] m2 = sollist[1] if m1 < m2: m1, m2 = m2, m1 # Irrespective of whether m1 - m2 is an integer or not, one # Frobenius series solution exists. serdict1 = _frobenius(terms-m1-1, m1, p0, q0, p, q, x0, x, C0) if not (m1 - m2).is_integer: # Second frobenius series solution exists. serdict2 = _frobenius(terms-m2-1, m2, p0, q0, p, q, x0, x, C1) else: # Check if second frobenius series solution exists. serdict2 = _frobenius(terms-m2-1, m2, p0, q0, p, q, x0, x, C1, check=m1) if serdict1: finalseries1 = C0 for key in serdict1: power = int(key.name[1:]) finalseries1 += serdict1[key]*(x - x0)**power finalseries1 = (x - x0)**m1*finalseries1 finalseries2 = S(0) if serdict2: for key in serdict2: power = int(key.name[1:]) finalseries2 += serdict2[key]*(x - x0)**power finalseries2 += C1 finalseries2 = (x - x0)**m2*finalseries2 return Eq(f(x), collect(finalseries1 + finalseries2, [C0, C1]) + Order(x**terms)) def _frobenius(n, m, p0, q0, p, q, x0, x, c, check=None): r""" Returns a dict with keys as coefficients and values as their values in terms of C0 """ n = int(n) # In cases where m1 - m2 is not an integer m2 = check d = Dummy("d") numsyms = numbered_symbols("C", start=0) numsyms = [next(numsyms) for i in range(n + 1)] C0 = Symbol("C0") serlist = [] for ser in [p, q]: # Order term not present if ser.is_polynomial(x) and Poly(ser, x).degree() <= n: if x0: ser = ser.subs(x, x + x0) dict_ = Poly(ser, x).as_dict() # Order term present else: tseries = series(ser, x=x0, n=n+1) # Removing order dict_ = Poly(list(ordered(tseries.args))[: -1], x).as_dict() # Fill in with zeros, if coefficients are zero. for i in range(n + 1): if (i,) not in dict_: dict_[(i,)] = S(0) serlist.append(dict_) pseries = serlist[0] qseries = serlist[1] indicial = d*(d - 1) + d*p0 + q0 frobdict = {} for i in range(1, n + 1): num = c*(m*pseries[(i,)] + qseries[(i,)]) for j in range(1, i): sym = Symbol("C" + str(j)) num += frobdict[sym]*((m + j)*pseries[(i - j,)] + qseries[(i - j,)]) # Checking for cases when m1 - m2 is an integer. If num equals zero # then a second Frobenius series solution cannot be found. If num is not zero # then set constant as zero and proceed. if m2 is not None and i == m2 - m: if num: return False else: frobdict[numsyms[i]] = S(0) else: frobdict[numsyms[i]] = -num/(indicial.subs(d, m+i)) return frobdict def _nth_algebraic_match(eq, func): r""" Matches any differential equation that nth_algebraic can solve. Uses `sympy.solve` but teaches it how to integrate derivatives. This involves calling `sympy.solve` and does most of the work of finding a solution (apart from evaluating the integrals). """ # Each integration should generate a different constant constants = iter(numbered_symbols(prefix='C', cls=Symbol, start=1)) constant = lambda: next(constants, None) # Like Derivative but "invertible" class diffx(Function): def inverse(self): # We mustn't use integrate here because fx has been replaced by _t # in the equation so integrals will not be correct while solve is # still working. return lambda expr: Integral(expr, var) + constant() # Replace derivatives wrt the independent variable with diffx def replace(eq, var): def expand_diffx(*args): differand, diffs = args[0], args[1:] toreplace = differand for v, n in diffs: for _ in range(n): if v == var: toreplace = diffx(toreplace) else: toreplace = Derivative(toreplace, v) return toreplace return eq.replace(Derivative, expand_diffx) # Restore derivatives in solution afterwards def unreplace(eq, var): return eq.replace(diffx, lambda e: Derivative(e, var)) # The independent variable var = func.args[0] subs_eqn = replace(eq, var) try: solns = solve(subs_eqn, func) except NotImplementedError: solns = [] solns = [unreplace(soln, var) for soln in solns] solns = [Equality(func, soln) for soln in solns] return {'var':var, 'solutions':solns} def ode_nth_algebraic(eq, func, order, match): r""" Solves an `n`\th order ordinary differential equation using algebra and integrals. There is no general form for the kind of equation that this can solve. The the equation is solved algebraically treating differentiation as an invertible algebraic function. Examples ======== >>> from sympy import Function, dsolve, Eq >>> from sympy.abc import x >>> f = Function('f') >>> eq = Eq(f(x) * (f(x).diff(x)**2 - 1), 0) >>> dsolve(eq, f(x), hint='nth_algebraic') ... # doctest: +NORMALIZE_WHITESPACE [Eq(f(x), 0), Eq(f(x), C1 - x), Eq(f(x), C1 + x)] Note that this solver can return algebraic solutions that do not have any integration constants (f(x) = 0 in the above example). # indirect doctest """ solns = match['solutions'] var = match['var'] solns = _nth_algebraic_remove_redundant_solutions(eq, solns, order, var) if len(solns) == 1: return solns[0] else: return solns # FIXME: Maybe something like this function should be applied to the solutions # returned by dsolve in general rather than just for nth_algebraic... def _nth_algebraic_remove_redundant_solutions(eq, solns, order, var): r""" Remove redundant solutions from the set of solutions returned by nth_algebraic. This function is needed because otherwise nth_algebraic can return redundant solutions where both algebraic solutions and integral solutions are found to the ODE. As an example consider: eq = Eq(f(x) * f(x).diff(x), 0) There are two ways to find solutions to eq. The first is the algebraic solution f(x)=0. The second is to solve the equation f(x).diff(x) = 0 leading to the solution f(x) = C1. In this particular case we then see that the first solution is a special case of the second and we don't want to return it. This does not always happen for algebraic solutions though since if we have eq = Eq(f(x)*(1 + f(x).diff(x)), 0) then we get the algebraic solution f(x) = 0 and the integral solution f(x) = -x + C1 and in this case the two solutions are not equivalent wrt initial conditions so both should be returned. """ def is_special_case_of(soln1, soln2): return _nth_algebraic_is_special_case_of(soln1, soln2, eq, order, var) unique_solns = [] for soln1 in solns: for soln2 in unique_solns[:]: if is_special_case_of(soln1, soln2): break elif is_special_case_of(soln2, soln1): unique_solns.remove(soln2) else: unique_solns.append(soln1) return unique_solns def _nth_algebraic_is_special_case_of(soln1, soln2, eq, order, var): r""" True if soln1 is found to be a special case of soln2 wrt some value of the constants that appear in soln2. False otherwise. """ # The solutions returned by nth_algebraic should be given explicitly as in # Eq(f(x), expr). We will equate the RHSs of the two solutions giving an # equation f1(x) = f2(x). # # Since this is supposed to hold for all x it also holds for derivatives # f1'(x) and f2'(x). For an order n ode we should be able to differentiate # each solution n times to get n+1 equations. # # We then try to solve those n+1 equations for the integrations constants # in f2(x). If we can find a solution that doesn't depend on x then it # means that some value of the constants in f1(x) is a special case of # f2(x) corresponding to a paritcular choice of the integration constants. constants1 = soln1.free_symbols.difference(eq.free_symbols) constants2 = soln2.free_symbols.difference(eq.free_symbols) constants1_new = get_numbered_constants(soln1.rhs - soln2.rhs, len(constants1)) if len(constants1) == 1: constants1_new = {constants1_new} for c_old, c_new in zip(constants1, constants1_new): soln1 = soln1.subs(c_old, c_new) # n equations for f1(x)=f2(x), f1'(x)=f2'(x), ... lhs = soln1.rhs.doit() rhs = soln2.rhs.doit() eqns = [Eq(lhs, rhs)] for n in range(1, order): lhs = lhs.diff(var) rhs = rhs.diff(var) eq = Eq(lhs, rhs) eqns.append(eq) # BooleanTrue/False awkwardly show up for trivial equations if any(isinstance(eq, BooleanFalse) for eq in eqns): return False eqns = [eq for eq in eqns if not isinstance(eq, BooleanTrue)] constant_solns = solve(eqns, constants2) # Sometimes returns a dict and sometimes a list of dicts if isinstance(constant_solns, dict): constant_solns = [constant_solns] # If any solution gives all constants as expressions that don't depend on # x then there exists constants for soln2 that give soln1 for constant_soln in constant_solns: if not any(c.has(var) for c in constant_soln.values()): return True else: return False def _nth_linear_match(eq, func, order): r""" Matches a differential equation to the linear form: .. math:: a_n(x) y^{(n)} + \cdots + a_1(x)y' + a_0(x) y + B(x) = 0 Returns a dict of order:coeff terms, where order is the order of the derivative on each term, and coeff is the coefficient of that derivative. The key ``-1`` holds the function `B(x)`. Returns ``None`` if the ODE is not linear. This function assumes that ``func`` has already been checked to be good. Examples ======== >>> from sympy import Function, cos, sin >>> from sympy.abc import x >>> from sympy.solvers.ode import _nth_linear_match >>> f = Function('f') >>> _nth_linear_match(f(x).diff(x, 3) + 2*f(x).diff(x) + ... x*f(x).diff(x, 2) + cos(x)*f(x).diff(x) + x - f(x) - ... sin(x), f(x), 3) {-1: x - sin(x), 0: -1, 1: cos(x) + 2, 2: x, 3: 1} >>> _nth_linear_match(f(x).diff(x, 3) + 2*f(x).diff(x) + ... x*f(x).diff(x, 2) + cos(x)*f(x).diff(x) + x - f(x) - ... sin(f(x)), f(x), 3) == None True """ x = func.args[0] one_x = {x} terms = {i: S.Zero for i in range(-1, order + 1)} for i in Add.make_args(eq): if not i.has(func): terms[-1] += i else: c, f = i.as_independent(func) if (isinstance(f, Derivative) and set(f.variables) == one_x and f.args[0] == func): terms[f.derivative_count] += c elif f == func: terms[len(f.args[1:])] += c else: return None return terms def ode_nth_linear_euler_eq_homogeneous(eq, func, order, match, returns='sol'): r""" Solves an `n`\th order linear homogeneous variable-coefficient Cauchy-Euler equidimensional ordinary differential equation. This is an equation with form `0 = a_0 f(x) + a_1 x f'(x) + a_2 x^2 f''(x) \cdots`. These equations can be solved in a general manner, by substituting solutions of the form `f(x) = x^r`, and deriving a characteristic equation for `r`. When there are repeated roots, we include extra terms of the form `C_{r k} \ln^k(x) x^r`, where `C_{r k}` is an arbitrary integration constant, `r` is a root of the characteristic equation, and `k` ranges over the multiplicity of `r`. In the cases where the roots are complex, solutions of the form `C_1 x^a \sin(b \log(x)) + C_2 x^a \cos(b \log(x))` are returned, based on expansions with Euler's formula. The general solution is the sum of the terms found. If SymPy cannot find exact roots to the characteristic equation, a :py:class:`~sympy.polys.rootoftools.CRootOf` instance will be returned instead. >>> from sympy import Function, dsolve, Eq >>> from sympy.abc import x >>> f = Function('f') >>> dsolve(4*x**2*f(x).diff(x, 2) + f(x), f(x), ... hint='nth_linear_euler_eq_homogeneous') ... # doctest: +NORMALIZE_WHITESPACE Eq(f(x), sqrt(x)*(C1 + C2*log(x))) Note that because this method does not involve integration, there is no ``nth_linear_euler_eq_homogeneous_Integral`` hint. The following is for internal use: - ``returns = 'sol'`` returns the solution to the ODE. - ``returns = 'list'`` returns a list of linearly independent solutions, corresponding to the fundamental solution set, for use with non homogeneous solution methods like variation of parameters and undetermined coefficients. Note that, though the solutions should be linearly independent, this function does not explicitly check that. You can do ``assert simplify(wronskian(sollist)) != 0`` to check for linear independence. Also, ``assert len(sollist) == order`` will need to pass. - ``returns = 'both'``, return a dictionary ``{'sol': <solution to ODE>, 'list': <list of linearly independent solutions>}``. Examples ======== >>> from sympy import Function, dsolve, pprint >>> from sympy.abc import x >>> f = Function('f') >>> eq = f(x).diff(x, 2)*x**2 - 4*f(x).diff(x)*x + 6*f(x) >>> pprint(dsolve(eq, f(x), ... hint='nth_linear_euler_eq_homogeneous')) 2 f(x) = x *(C1 + C2*x) References ========== - https://en.wikipedia.org/wiki/Cauchy%E2%80%93Euler_equation - C. Bender & S. Orszag, "Advanced Mathematical Methods for Scientists and Engineers", Springer 1999, pp. 12 # indirect doctest """ global collectterms collectterms = [] x = func.args[0] f = func.func r = match # First, set up characteristic equation. chareq, symbol = S.Zero, Dummy('x') for i in r.keys(): if not isinstance(i, str) and i >= 0: chareq += (r[i]*diff(x**symbol, x, i)*x**-symbol).expand() chareq = Poly(chareq, symbol) chareqroots = [rootof(chareq, k) for k in range(chareq.degree())] # A generator of constants constants = list(get_numbered_constants(eq, num=chareq.degree()*2)) constants.reverse() # Create a dict root: multiplicity or charroots charroots = defaultdict(int) for root in chareqroots: charroots[root] += 1 gsol = S(0) # We need keep track of terms so we can run collect() at the end. # This is necessary for constantsimp to work properly. ln = log for root, multiplicity in charroots.items(): for i in range(multiplicity): if isinstance(root, RootOf): gsol += (x**root) * constants.pop() if multiplicity != 1: raise ValueError("Value should be 1") collectterms = [(0, root, 0)] + collectterms elif root.is_real: gsol += ln(x)**i*(x**root) * constants.pop() collectterms = [(i, root, 0)] + collectterms else: reroot = re(root) imroot = im(root) gsol += ln(x)**i * (x**reroot) * ( constants.pop() * sin(abs(imroot)*ln(x)) + constants.pop() * cos(imroot*ln(x))) # Preserve ordering (multiplicity, real part, imaginary part) # It will be assumed implicitly when constructing # fundamental solution sets. collectterms = [(i, reroot, imroot)] + collectterms if returns == 'sol': return Eq(f(x), gsol) elif returns in ('list' 'both'): # HOW TO TEST THIS CODE? (dsolve does not pass 'returns' through) # Create a list of (hopefully) linearly independent solutions gensols = [] # Keep track of when to use sin or cos for nonzero imroot for i, reroot, imroot in collectterms: if imroot == 0: gensols.append(ln(x)**i*x**reroot) else: sin_form = ln(x)**i*x**reroot*sin(abs(imroot)*ln(x)) if sin_form in gensols: cos_form = ln(x)**i*x**reroot*cos(imroot*ln(x)) gensols.append(cos_form) else: gensols.append(sin_form) if returns == 'list': return gensols else: return {'sol': Eq(f(x), gsol), 'list': gensols} else: raise ValueError('Unknown value for key "returns".') def ode_nth_linear_euler_eq_nonhomogeneous_undetermined_coefficients(eq, func, order, match, returns='sol'): r""" Solves an `n`\th order linear non homogeneous Cauchy-Euler equidimensional ordinary differential equation using undetermined coefficients. This is an equation with form `g(x) = a_0 f(x) + a_1 x f'(x) + a_2 x^2 f''(x) \cdots`. These equations can be solved in a general manner, by substituting solutions of the form `x = exp(t)`, and deriving a characteristic equation of form `g(exp(t)) = b_0 f(t) + b_1 f'(t) + b_2 f''(t) \cdots` which can be then solved by nth_linear_constant_coeff_undetermined_coefficients if g(exp(t)) has finite number of linearly independent derivatives. Functions that fit this requirement are finite sums functions of the form `a x^i e^{b x} \sin(c x + d)` or `a x^i e^{b x} \cos(c x + d)`, where `i` is a non-negative integer and `a`, `b`, `c`, and `d` are constants. For example any polynomial in `x`, functions like `x^2 e^{2 x}`, `x \sin(x)`, and `e^x \cos(x)` can all be used. Products of `\sin`'s and `\cos`'s have a finite number of derivatives, because they can be expanded into `\sin(a x)` and `\cos(b x)` terms. However, SymPy currently cannot do that expansion, so you will need to manually rewrite the expression in terms of the above to use this method. So, for example, you will need to manually convert `\sin^2(x)` into `(1 + \cos(2 x))/2` to properly apply the method of undetermined coefficients on it. After replacement of x by exp(t), this method works by creating a trial function from the expression and all of its linear independent derivatives and substituting them into the original ODE. The coefficients for each term will be a system of linear equations, which are be solved for and substituted, giving the solution. If any of the trial functions are linearly dependent on the solution to the homogeneous equation, they are multiplied by sufficient `x` to make them linearly independent. Examples ======== >>> from sympy import dsolve, Function, Derivative, log >>> from sympy.abc import x >>> f = Function('f') >>> eq = x**2*Derivative(f(x), x, x) - 2*x*Derivative(f(x), x) + 2*f(x) - log(x) >>> dsolve(eq, f(x), ... hint='nth_linear_euler_eq_nonhomogeneous_undetermined_coefficients').expand() Eq(f(x), C1*x + C2*x**2 + log(x)/2 + 3/4) """ x = func.args[0] f = func.func r = match chareq, eq, symbol = S.Zero, S.Zero, Dummy('x') for i in r.keys(): if not isinstance(i, str) and i >= 0: chareq += (r[i]*diff(x**symbol, x, i)*x**-symbol).expand() for i in range(1,degree(Poly(chareq, symbol))+1): eq += chareq.coeff(symbol**i)*diff(f(x), x, i) if chareq.as_coeff_add(symbol)[0]: eq += chareq.as_coeff_add(symbol)[0]*f(x) e, re = posify(r[-1].subs(x, exp(x))) eq += e.subs(re) match = _nth_linear_match(eq, f(x), ode_order(eq, f(x))) match['trialset'] = r['trialset'] return ode_nth_linear_constant_coeff_undetermined_coefficients(eq, func, order, match).subs(x, log(x)).subs(f(log(x)), f(x)).expand() def ode_nth_linear_euler_eq_nonhomogeneous_variation_of_parameters(eq, func, order, match, returns='sol'): r""" Solves an `n`\th order linear non homogeneous Cauchy-Euler equidimensional ordinary differential equation using variation of parameters. This is an equation with form `g(x) = a_0 f(x) + a_1 x f'(x) + a_2 x^2 f''(x) \cdots`. This method works by assuming that the particular solution takes the form .. math:: \sum_{x=1}^{n} c_i(x) y_i(x) {a_n} {x^n} \text{,} where `y_i` is the `i`\th solution to the homogeneous equation. The solution is then solved using Wronskian's and Cramer's Rule. The particular solution is given by multiplying eq given below with `a_n x^{n}` .. math:: \sum_{x=1}^n \left( \int \frac{W_i(x)}{W(x)} \,dx \right) y_i(x) \text{,} where `W(x)` is the Wronskian of the fundamental system (the system of `n` linearly independent solutions to the homogeneous equation), and `W_i(x)` is the Wronskian of the fundamental system with the `i`\th column replaced with `[0, 0, \cdots, 0, \frac{x^{- n}}{a_n} g{\left(x \right)}]`. This method is general enough to solve any `n`\th order inhomogeneous linear differential equation, but sometimes SymPy cannot simplify the Wronskian well enough to integrate it. If this method hangs, try using the ``nth_linear_constant_coeff_variation_of_parameters_Integral`` hint and simplifying the integrals manually. Also, prefer using ``nth_linear_constant_coeff_undetermined_coefficients`` when it applies, because it doesn't use integration, making it faster and more reliable. Warning, using simplify=False with 'nth_linear_constant_coeff_variation_of_parameters' in :py:meth:`~sympy.solvers.ode.dsolve` may cause it to hang, because it will not attempt to simplify the Wronskian before integrating. It is recommended that you only use simplify=False with 'nth_linear_constant_coeff_variation_of_parameters_Integral' for this method, especially if the solution to the homogeneous equation has trigonometric functions in it. Examples ======== >>> from sympy import Function, dsolve, Derivative >>> from sympy.abc import x >>> f = Function('f') >>> eq = x**2*Derivative(f(x), x, x) - 2*x*Derivative(f(x), x) + 2*f(x) - x**4 >>> dsolve(eq, f(x), ... hint='nth_linear_euler_eq_nonhomogeneous_variation_of_parameters').expand() Eq(f(x), C1*x + C2*x**2 + x**4/6) """ x = func.args[0] f = func.func r = match gensol = ode_nth_linear_euler_eq_homogeneous(eq, func, order, match, returns='both') match.update(gensol) r[-1] = r[-1]/r[ode_order(eq, f(x))] sol = _solve_variation_of_parameters(eq, func, order, match) return Eq(f(x), r['sol'].rhs + (sol.rhs - r['sol'].rhs)*r[ode_order(eq, f(x))]) def ode_almost_linear(eq, func, order, match): r""" Solves an almost-linear differential equation. The general form of an almost linear differential equation is .. math:: f(x) g(y) y + k(x) l(y) + m(x) = 0 \text{where} l'(y) = g(y)\text{.} This can be solved by substituting `l(y) = u(y)`. Making the given substitution reduces it to a linear differential equation of the form `u' + P(x) u + Q(x) = 0`. The general solution is >>> from sympy import Function, dsolve, Eq, pprint >>> from sympy.abc import x, y, n >>> f, g, k, l = map(Function, ['f', 'g', 'k', 'l']) >>> genform = Eq(f(x)*(l(y).diff(y)) + k(x)*l(y) + g(x)) >>> pprint(genform) d f(x)*--(l(y)) + g(x) + k(x)*l(y) = 0 dy >>> pprint(dsolve(genform, hint = 'almost_linear')) / // y*k(x) \\ | || ------ || | || f(x) || -y*k(x) | ||-g(x)*e || -------- | ||-------------- for k(x) != 0|| f(x) l(y) = |C1 + |< k(x) ||*e | || || | || -y*g(x) || | || -------- otherwise || | || f(x) || \ \\ // See Also ======== :meth:`sympy.solvers.ode.ode_1st_linear` Examples ======== >>> from sympy import Function, Derivative, pprint >>> from sympy.solvers.ode import dsolve, classify_ode >>> from sympy.abc import x >>> f = Function('f') >>> d = f(x).diff(x) >>> eq = x*d + x*f(x) + 1 >>> dsolve(eq, f(x), hint='almost_linear') Eq(f(x), (C1 - Ei(x))*exp(-x)) >>> pprint(dsolve(eq, f(x), hint='almost_linear')) -x f(x) = (C1 - Ei(x))*e References ========== - Joel Moses, "Symbolic Integration - The Stormy Decade", Communications of the ACM, Volume 14, Number 8, August 1971, pp. 558 """ # Since ode_1st_linear has already been implemented, and the # coefficients have been modified to the required form in # classify_ode, just passing eq, func, order and match to # ode_1st_linear will give the required output. return ode_1st_linear(eq, func, order, match) def _linear_coeff_match(expr, func): r""" Helper function to match hint ``linear_coefficients``. Matches the expression to the form `(a_1 x + b_1 f(x) + c_1)/(a_2 x + b_2 f(x) + c_2)` where the following conditions hold: 1. `a_1`, `b_1`, `c_1`, `a_2`, `b_2`, `c_2` are Rationals; 2. `c_1` or `c_2` are not equal to zero; 3. `a_2 b_1 - a_1 b_2` is not equal to zero. Return ``xarg``, ``yarg`` where 1. ``xarg`` = `(b_2 c_1 - b_1 c_2)/(a_2 b_1 - a_1 b_2)` 2. ``yarg`` = `(a_1 c_2 - a_2 c_1)/(a_2 b_1 - a_1 b_2)` Examples ======== >>> from sympy import Function >>> from sympy.abc import x >>> from sympy.solvers.ode import _linear_coeff_match >>> from sympy.functions.elementary.trigonometric import sin >>> f = Function('f') >>> _linear_coeff_match(( ... (-25*f(x) - 8*x + 62)/(4*f(x) + 11*x - 11)), f(x)) (1/9, 22/9) >>> _linear_coeff_match( ... sin((-5*f(x) - 8*x + 6)/(4*f(x) + x - 1)), f(x)) (19/27, 2/27) >>> _linear_coeff_match(sin(f(x)/x), f(x)) """ f = func.func x = func.args[0] def abc(eq): r''' Internal function of _linear_coeff_match that returns Rationals a, b, c if eq is a*x + b*f(x) + c, else None. ''' eq = _mexpand(eq) c = eq.as_independent(x, f(x), as_Add=True)[0] if not c.is_Rational: return a = eq.coeff(x) if not a.is_Rational: return b = eq.coeff(f(x)) if not b.is_Rational: return if eq == a*x + b*f(x) + c: return a, b, c def match(arg): r''' Internal function of _linear_coeff_match that returns Rationals a1, b1, c1, a2, b2, c2 and a2*b1 - a1*b2 of the expression (a1*x + b1*f(x) + c1)/(a2*x + b2*f(x) + c2) if one of c1 or c2 and a2*b1 - a1*b2 is non-zero, else None. ''' n, d = arg.together().as_numer_denom() m = abc(n) if m is not None: a1, b1, c1 = m m = abc(d) if m is not None: a2, b2, c2 = m d = a2*b1 - a1*b2 if (c1 or c2) and d: return a1, b1, c1, a2, b2, c2, d m = [fi.args[0] for fi in expr.atoms(Function) if fi.func != f and len(fi.args) == 1 and not fi.args[0].is_Function] or {expr} m1 = match(m.pop()) if m1 and all(match(mi) == m1 for mi in m): a1, b1, c1, a2, b2, c2, denom = m1 return (b2*c1 - b1*c2)/denom, (a1*c2 - a2*c1)/denom def ode_linear_coefficients(eq, func, order, match): r""" Solves a differential equation with linear coefficients. The general form of a differential equation with linear coefficients is .. math:: y' + F\left(\!\frac{a_1 x + b_1 y + c_1}{a_2 x + b_2 y + c_2}\!\right) = 0\text{,} where `a_1`, `b_1`, `c_1`, `a_2`, `b_2`, `c_2` are constants and `a_1 b_2 - a_2 b_1 \ne 0`. This can be solved by substituting: .. math:: x = x' + \frac{b_2 c_1 - b_1 c_2}{a_2 b_1 - a_1 b_2} y = y' + \frac{a_1 c_2 - a_2 c_1}{a_2 b_1 - a_1 b_2}\text{.} This substitution reduces the equation to a homogeneous differential equation. See Also ======== :meth:`sympy.solvers.ode.ode_1st_homogeneous_coeff_best` :meth:`sympy.solvers.ode.ode_1st_homogeneous_coeff_subs_indep_div_dep` :meth:`sympy.solvers.ode.ode_1st_homogeneous_coeff_subs_dep_div_indep` Examples ======== >>> from sympy import Function, Derivative, pprint >>> from sympy.solvers.ode import dsolve, classify_ode >>> from sympy.abc import x >>> f = Function('f') >>> df = f(x).diff(x) >>> eq = (x + f(x) + 1)*df + (f(x) - 6*x + 1) >>> dsolve(eq, hint='linear_coefficients') [Eq(f(x), -x - sqrt(C1 + 7*x**2) - 1), Eq(f(x), -x + sqrt(C1 + 7*x**2) - 1)] >>> pprint(dsolve(eq, hint='linear_coefficients')) ___________ ___________ / 2 / 2 [f(x) = -x - \/ C1 + 7*x - 1, f(x) = -x + \/ C1 + 7*x - 1] References ========== - Joel Moses, "Symbolic Integration - The Stormy Decade", Communications of the ACM, Volume 14, Number 8, August 1971, pp. 558 """ return ode_1st_homogeneous_coeff_best(eq, func, order, match) def ode_separable_reduced(eq, func, order, match): r""" Solves a differential equation that can be reduced to the separable form. The general form of this equation is .. math:: y' + (y/x) H(x^n y) = 0\text{}. This can be solved by substituting `u(y) = x^n y`. The equation then reduces to the separable form `\frac{u'}{u (\mathrm{power} - H(u))} - \frac{1}{x} = 0`. The general solution is: >>> from sympy import Function, dsolve, Eq, pprint >>> from sympy.abc import x, n >>> f, g = map(Function, ['f', 'g']) >>> genform = f(x).diff(x) + (f(x)/x)*g(x**n*f(x)) >>> pprint(genform) / n \ d f(x)*g\x *f(x)/ --(f(x)) + --------------- dx x >>> pprint(dsolve(genform, hint='separable_reduced')) n x *f(x) / | | 1 | ------------ dy = C1 + log(x) | y*(n - g(y)) | / See Also ======== :meth:`sympy.solvers.ode.ode_separable` Examples ======== >>> from sympy import Function, Derivative, pprint >>> from sympy.solvers.ode import dsolve, classify_ode >>> from sympy.abc import x >>> f = Function('f') >>> d = f(x).diff(x) >>> eq = (x - x**2*f(x))*d - f(x) >>> dsolve(eq, hint='separable_reduced') [Eq(f(x), (-sqrt(C1*x**2 + 1) + 1)/x), Eq(f(x), (sqrt(C1*x**2 + 1) + 1)/x)] >>> pprint(dsolve(eq, hint='separable_reduced')) ___________ ___________ / 2 / 2 - \/ C1*x + 1 + 1 \/ C1*x + 1 + 1 [f(x) = --------------------, f(x) = ------------------] x x References ========== - Joel Moses, "Symbolic Integration - The Stormy Decade", Communications of the ACM, Volume 14, Number 8, August 1971, pp. 558 """ # Arguments are passed in a way so that they are coherent with the # ode_separable function x = func.args[0] f = func.func y = Dummy('y') u = match['u'].subs(match['t'], y) ycoeff = 1/(y*(match['power'] - u)) m1 = {y: 1, x: -1/x, 'coeff': 1} m2 = {y: ycoeff, x: 1, 'coeff': 1} r = {'m1': m1, 'm2': m2, 'y': y, 'hint': x**match['power']*f(x)} return ode_separable(eq, func, order, r) def ode_1st_power_series(eq, func, order, match): r""" The power series solution is a method which gives the Taylor series expansion to the solution of a differential equation. For a first order differential equation `\frac{dy}{dx} = h(x, y)`, a power series solution exists at a point `x = x_{0}` if `h(x, y)` is analytic at `x_{0}`. The solution is given by .. math:: y(x) = y(x_{0}) + \sum_{n = 1}^{\infty} \frac{F_{n}(x_{0},b)(x - x_{0})^n}{n!}, where `y(x_{0}) = b` is the value of y at the initial value of `x_{0}`. To compute the values of the `F_{n}(x_{0},b)` the following algorithm is followed, until the required number of terms are generated. 1. `F_1 = h(x_{0}, b)` 2. `F_{n+1} = \frac{\partial F_{n}}{\partial x} + \frac{\partial F_{n}}{\partial y}F_{1}` Examples ======== >>> from sympy import Function, Derivative, pprint, exp >>> from sympy.solvers.ode import dsolve >>> from sympy.abc import x >>> f = Function('f') >>> eq = exp(x)*(f(x).diff(x)) - f(x) >>> pprint(dsolve(eq, hint='1st_power_series')) 3 4 5 C1*x C1*x C1*x / 6\ f(x) = C1 + C1*x - ----- + ----- + ----- + O\x / 6 24 60 References ========== - Travis W. Walker, Analytic power series technique for solving first-order differential equations, p.p 17, 18 """ x = func.args[0] y = match['y'] f = func.func h = -match[match['d']]/match[match['e']] point = match.get('f0') value = match.get('f0val') terms = match.get('terms') # First term F = h if not h: return Eq(f(x), value) # Initialization series = value if terms > 1: hc = h.subs({x: point, y: value}) if hc.has(oo) or hc.has(NaN) or hc.has(zoo): # Derivative does not exist, not analytic return Eq(f(x), oo) elif hc: series += hc*(x - point) for factcount in range(2, terms): Fnew = F.diff(x) + F.diff(y)*h Fnewc = Fnew.subs({x: point, y: value}) # Same logic as above if Fnewc.has(oo) or Fnewc.has(NaN) or Fnewc.has(-oo) or Fnewc.has(zoo): return Eq(f(x), oo) series += Fnewc*((x - point)**factcount)/factorial(factcount) F = Fnew series += Order(x**terms) return Eq(f(x), series) def ode_nth_linear_constant_coeff_homogeneous(eq, func, order, match, returns='sol'): r""" Solves an `n`\th order linear homogeneous differential equation with constant coefficients. This is an equation of the form .. math:: a_n f^{(n)}(x) + a_{n-1} f^{(n-1)}(x) + \cdots + a_1 f'(x) + a_0 f(x) = 0\text{.} These equations can be solved in a general manner, by taking the roots of the characteristic equation `a_n m^n + a_{n-1} m^{n-1} + \cdots + a_1 m + a_0 = 0`. The solution will then be the sum of `C_n x^i e^{r x}` terms, for each where `C_n` is an arbitrary constant, `r` is a root of the characteristic equation and `i` is one of each from 0 to the multiplicity of the root - 1 (for example, a root 3 of multiplicity 2 would create the terms `C_1 e^{3 x} + C_2 x e^{3 x}`). The exponential is usually expanded for complex roots using Euler's equation `e^{I x} = \cos(x) + I \sin(x)`. Complex roots always come in conjugate pairs in polynomials with real coefficients, so the two roots will be represented (after simplifying the constants) as `e^{a x} \left(C_1 \cos(b x) + C_2 \sin(b x)\right)`. If SymPy cannot find exact roots to the characteristic equation, a :py:class:`~sympy.polys.rootoftools.CRootOf` instance will be return instead. >>> from sympy import Function, dsolve, Eq >>> from sympy.abc import x >>> f = Function('f') >>> dsolve(f(x).diff(x, 5) + 10*f(x).diff(x) - 2*f(x), f(x), ... hint='nth_linear_constant_coeff_homogeneous') ... # doctest: +NORMALIZE_WHITESPACE Eq(f(x), C5*exp(x*CRootOf(_x**5 + 10*_x - 2, 0)) + (C1*sin(x*im(CRootOf(_x**5 + 10*_x - 2, 1))) + C2*cos(x*im(CRootOf(_x**5 + 10*_x - 2, 1))))*exp(x*re(CRootOf(_x**5 + 10*_x - 2, 1))) + (C3*sin(x*im(CRootOf(_x**5 + 10*_x - 2, 3))) + C4*cos(x*im(CRootOf(_x**5 + 10*_x - 2, 3))))*exp(x*re(CRootOf(_x**5 + 10*_x - 2, 3)))) Note that because this method does not involve integration, there is no ``nth_linear_constant_coeff_homogeneous_Integral`` hint. The following is for internal use: - ``returns = 'sol'`` returns the solution to the ODE. - ``returns = 'list'`` returns a list of linearly independent solutions, for use with non homogeneous solution methods like variation of parameters and undetermined coefficients. Note that, though the solutions should be linearly independent, this function does not explicitly check that. You can do ``assert simplify(wronskian(sollist)) != 0`` to check for linear independence. Also, ``assert len(sollist) == order`` will need to pass. - ``returns = 'both'``, return a dictionary ``{'sol': <solution to ODE>, 'list': <list of linearly independent solutions>}``. Examples ======== >>> from sympy import Function, dsolve, pprint >>> from sympy.abc import x >>> f = Function('f') >>> pprint(dsolve(f(x).diff(x, 4) + 2*f(x).diff(x, 3) - ... 2*f(x).diff(x, 2) - 6*f(x).diff(x) + 5*f(x), f(x), ... hint='nth_linear_constant_coeff_homogeneous')) x -2*x f(x) = (C1 + C2*x)*e + (C3*sin(x) + C4*cos(x))*e References ========== - https://en.wikipedia.org/wiki/Linear_differential_equation section: Nonhomogeneous_equation_with_constant_coefficients - M. Tenenbaum & H. Pollard, "Ordinary Differential Equations", Dover 1963, pp. 211 # indirect doctest """ x = func.args[0] f = func.func r = match # First, set up characteristic equation. chareq, symbol = S.Zero, Dummy('x') for i in r.keys(): if type(i) == str or i < 0: pass else: chareq += r[i]*symbol**i chareq = Poly(chareq, symbol) # Can't just call roots because it doesn't return rootof for unsolveable # polynomials. chareqroots = roots(chareq, multiple=True) if len(chareqroots) != order: chareqroots = [rootof(chareq, k) for k in range(chareq.degree())] chareq_is_complex = not all([i.is_real for i in chareq.all_coeffs()]) # A generator of constants constants = list(get_numbered_constants(eq, num=chareq.degree()*2)) # Create a dict root: multiplicity or charroots charroots = defaultdict(int) for root in chareqroots: charroots[root] += 1 gsol = S(0) # We need to keep track of terms so we can run collect() at the end. # This is necessary for constantsimp to work properly. global collectterms collectterms = [] gensols = [] conjugate_roots = [] # used to prevent double-use of conjugate roots # Loop over roots in theorder provided by roots/rootof... for root in chareqroots: # but don't repoeat multiple roots. if root not in charroots: continue multiplicity = charroots.pop(root) for i in range(multiplicity): if chareq_is_complex: gensols.append(x**i*exp(root*x)) collectterms = [(i, root, 0)] + collectterms continue reroot = re(root) imroot = im(root) if imroot.has(atan2) and reroot.has(atan2): # Remove this condition when re and im stop returning # circular atan2 usages. gensols.append(x**i*exp(root*x)) collectterms = [(i, root, 0)] + collectterms else: if root in conjugate_roots: collectterms = [(i, reroot, imroot)] + collectterms continue if imroot == 0: gensols.append(x**i*exp(reroot*x)) collectterms = [(i, reroot, 0)] + collectterms continue conjugate_roots.append(conjugate(root)) gensols.append(x**i*exp(reroot*x) * sin(abs(imroot) * x)) gensols.append(x**i*exp(reroot*x) * cos( imroot * x)) # This ordering is important collectterms = [(i, reroot, imroot)] + collectterms if returns == 'list': return gensols elif returns in ('sol' 'both'): gsol = Add(*[i*j for (i,j) in zip(constants, gensols)]) if returns == 'sol': return Eq(f(x), gsol) else: return {'sol': Eq(f(x), gsol), 'list': gensols} else: raise ValueError('Unknown value for key "returns".') def ode_nth_linear_constant_coeff_undetermined_coefficients(eq, func, order, match): r""" Solves an `n`\th order linear differential equation with constant coefficients using the method of undetermined coefficients. This method works on differential equations of the form .. math:: a_n f^{(n)}(x) + a_{n-1} f^{(n-1)}(x) + \cdots + a_1 f'(x) + a_0 f(x) = P(x)\text{,} where `P(x)` is a function that has a finite number of linearly independent derivatives. Functions that fit this requirement are finite sums functions of the form `a x^i e^{b x} \sin(c x + d)` or `a x^i e^{b x} \cos(c x + d)`, where `i` is a non-negative integer and `a`, `b`, `c`, and `d` are constants. For example any polynomial in `x`, functions like `x^2 e^{2 x}`, `x \sin(x)`, and `e^x \cos(x)` can all be used. Products of `\sin`'s and `\cos`'s have a finite number of derivatives, because they can be expanded into `\sin(a x)` and `\cos(b x)` terms. However, SymPy currently cannot do that expansion, so you will need to manually rewrite the expression in terms of the above to use this method. So, for example, you will need to manually convert `\sin^2(x)` into `(1 + \cos(2 x))/2` to properly apply the method of undetermined coefficients on it. This method works by creating a trial function from the expression and all of its linear independent derivatives and substituting them into the original ODE. The coefficients for each term will be a system of linear equations, which are be solved for and substituted, giving the solution. If any of the trial functions are linearly dependent on the solution to the homogeneous equation, they are multiplied by sufficient `x` to make them linearly independent. Examples ======== >>> from sympy import Function, dsolve, pprint, exp, cos >>> from sympy.abc import x >>> f = Function('f') >>> pprint(dsolve(f(x).diff(x, 2) + 2*f(x).diff(x) + f(x) - ... 4*exp(-x)*x**2 + cos(2*x), f(x), ... hint='nth_linear_constant_coeff_undetermined_coefficients')) / 4\ | x | -x 4*sin(2*x) 3*cos(2*x) f(x) = |C1 + C2*x + --|*e - ---------- + ---------- \ 3 / 25 25 References ========== - https://en.wikipedia.org/wiki/Method_of_undetermined_coefficients - M. Tenenbaum & H. Pollard, "Ordinary Differential Equations", Dover 1963, pp. 221 # indirect doctest """ gensol = ode_nth_linear_constant_coeff_homogeneous(eq, func, order, match, returns='both') match.update(gensol) return _solve_undetermined_coefficients(eq, func, order, match) def _solve_undetermined_coefficients(eq, func, order, match): r""" Helper function for the method of undetermined coefficients. See the :py:meth:`~sympy.solvers.ode.ode_nth_linear_constant_coeff_undetermined_coefficients` docstring for more information on this method. The parameter ``match`` should be a dictionary that has the following keys: ``list`` A list of solutions to the homogeneous equation, such as the list returned by ``ode_nth_linear_constant_coeff_homogeneous(returns='list')``. ``sol`` The general solution, such as the solution returned by ``ode_nth_linear_constant_coeff_homogeneous(returns='sol')``. ``trialset`` The set of trial functions as returned by ``_undetermined_coefficients_match()['trialset']``. """ x = func.args[0] f = func.func r = match coeffs = numbered_symbols('a', cls=Dummy) coefflist = [] gensols = r['list'] gsol = r['sol'] trialset = r['trialset'] notneedset = set([]) newtrialset = set([]) global collectterms if len(gensols) != order: raise NotImplementedError("Cannot find " + str(order) + " solutions to the homogeneous equation necessary to apply" + " undetermined coefficients to " + str(eq) + " (number of terms != order)") usedsin = set([]) mult = 0 # The multiplicity of the root getmult = True for i, reroot, imroot in collectterms: if getmult: mult = i + 1 getmult = False if i == 0: getmult = True if imroot: # Alternate between sin and cos if (i, reroot) in usedsin: check = x**i*exp(reroot*x)*cos(imroot*x) else: check = x**i*exp(reroot*x)*sin(abs(imroot)*x) usedsin.add((i, reroot)) else: check = x**i*exp(reroot*x) if check in trialset: # If an element of the trial function is already part of the # homogeneous solution, we need to multiply by sufficient x to # make it linearly independent. We also don't need to bother # checking for the coefficients on those elements, since we # already know it will be 0. while True: if check*x**mult in trialset: mult += 1 else: break trialset.add(check*x**mult) notneedset.add(check) newtrialset = trialset - notneedset trialfunc = 0 for i in newtrialset: c = next(coeffs) coefflist.append(c) trialfunc += c*i eqs = sub_func_doit(eq, f(x), trialfunc) coeffsdict = dict(list(zip(trialset, [0]*(len(trialset) + 1)))) eqs = _mexpand(eqs) for i in Add.make_args(eqs): s = separatevars(i, dict=True, symbols=[x]) coeffsdict[s[x]] += s['coeff'] coeffvals = solve(list(coeffsdict.values()), coefflist) if not coeffvals: raise NotImplementedError( "Could not solve `%s` using the " "method of undetermined coefficients " "(unable to solve for coefficients)." % eq) psol = trialfunc.subs(coeffvals) return Eq(f(x), gsol.rhs + psol) def _undetermined_coefficients_match(expr, x): r""" Returns a trial function match if undetermined coefficients can be applied to ``expr``, and ``None`` otherwise. A trial expression can be found for an expression for use with the method of undetermined coefficients if the expression is an additive/multiplicative combination of constants, polynomials in `x` (the independent variable of expr), `\sin(a x + b)`, `\cos(a x + b)`, and `e^{a x}` terms (in other words, it has a finite number of linearly independent derivatives). Note that you may still need to multiply each term returned here by sufficient `x` to make it linearly independent with the solutions to the homogeneous equation. This is intended for internal use by ``undetermined_coefficients`` hints. SymPy currently has no way to convert `\sin^n(x) \cos^m(y)` into a sum of only `\sin(a x)` and `\cos(b x)` terms, so these are not implemented. So, for example, you will need to manually convert `\sin^2(x)` into `[1 + \cos(2 x)]/2` to properly apply the method of undetermined coefficients on it. Examples ======== >>> from sympy import log, exp >>> from sympy.solvers.ode import _undetermined_coefficients_match >>> from sympy.abc import x >>> _undetermined_coefficients_match(9*x*exp(x) + exp(-x), x) {'test': True, 'trialset': {x*exp(x), exp(-x), exp(x)}} >>> _undetermined_coefficients_match(log(x), x) {'test': False} """ a = Wild('a', exclude=[x]) b = Wild('b', exclude=[x]) expr = powsimp(expr, combine='exp') # exp(x)*exp(2*x + 1) => exp(3*x + 1) retdict = {} def _test_term(expr, x): r""" Test if ``expr`` fits the proper form for undetermined coefficients. """ if not expr.has(x): return True elif expr.is_Add: return all(_test_term(i, x) for i in expr.args) elif expr.is_Mul: if expr.has(sin, cos): foundtrig = False # Make sure that there is only one trig function in the args. # See the docstring. for i in expr.args: if i.has(sin, cos): if foundtrig: return False else: foundtrig = True return all(_test_term(i, x) for i in expr.args) elif expr.is_Function: if expr.func in (sin, cos, exp): if expr.args[0].match(a*x + b): return True else: return False else: return False elif expr.is_Pow and expr.base.is_Symbol and expr.exp.is_Integer and \ expr.exp >= 0: return True elif expr.is_Pow and expr.base.is_number: if expr.exp.match(a*x + b): return True else: return False elif expr.is_Symbol or expr.is_number: return True else: return False def _get_trial_set(expr, x, exprs=set([])): r""" Returns a set of trial terms for undetermined coefficients. The idea behind undetermined coefficients is that the terms expression repeat themselves after a finite number of derivatives, except for the coefficients (they are linearly dependent). So if we collect these, we should have the terms of our trial function. """ def _remove_coefficient(expr, x): r""" Returns the expression without a coefficient. Similar to expr.as_independent(x)[1], except it only works multiplicatively. """ term = S.One if expr.is_Mul: for i in expr.args: if i.has(x): term *= i elif expr.has(x): term = expr return term expr = expand_mul(expr) if expr.is_Add: for term in expr.args: if _remove_coefficient(term, x) in exprs: pass else: exprs.add(_remove_coefficient(term, x)) exprs = exprs.union(_get_trial_set(term, x, exprs)) else: term = _remove_coefficient(expr, x) tmpset = exprs.union({term}) oldset = set([]) while tmpset != oldset: # If you get stuck in this loop, then _test_term is probably # broken oldset = tmpset.copy() expr = expr.diff(x) term = _remove_coefficient(expr, x) if term.is_Add: tmpset = tmpset.union(_get_trial_set(term, x, tmpset)) else: tmpset.add(term) exprs = tmpset return exprs retdict['test'] = _test_term(expr, x) if retdict['test']: # Try to generate a list of trial solutions that will have the # undetermined coefficients. Note that if any of these are not linearly # independent with any of the solutions to the homogeneous equation, # then they will need to be multiplied by sufficient x to make them so. # This function DOES NOT do that (it doesn't even look at the # homogeneous equation). retdict['trialset'] = _get_trial_set(expr, x) return retdict def ode_nth_linear_constant_coeff_variation_of_parameters(eq, func, order, match): r""" Solves an `n`\th order linear differential equation with constant coefficients using the method of variation of parameters. This method works on any differential equations of the form .. math:: f^{(n)}(x) + a_{n-1} f^{(n-1)}(x) + \cdots + a_1 f'(x) + a_0 f(x) = P(x)\text{.} This method works by assuming that the particular solution takes the form .. math:: \sum_{x=1}^{n} c_i(x) y_i(x)\text{,} where `y_i` is the `i`\th solution to the homogeneous equation. The solution is then solved using Wronskian's and Cramer's Rule. The particular solution is given by .. math:: \sum_{x=1}^n \left( \int \frac{W_i(x)}{W(x)} \,dx \right) y_i(x) \text{,} where `W(x)` is the Wronskian of the fundamental system (the system of `n` linearly independent solutions to the homogeneous equation), and `W_i(x)` is the Wronskian of the fundamental system with the `i`\th column replaced with `[0, 0, \cdots, 0, P(x)]`. This method is general enough to solve any `n`\th order inhomogeneous linear differential equation with constant coefficients, but sometimes SymPy cannot simplify the Wronskian well enough to integrate it. If this method hangs, try using the ``nth_linear_constant_coeff_variation_of_parameters_Integral`` hint and simplifying the integrals manually. Also, prefer using ``nth_linear_constant_coeff_undetermined_coefficients`` when it applies, because it doesn't use integration, making it faster and more reliable. Warning, using simplify=False with 'nth_linear_constant_coeff_variation_of_parameters' in :py:meth:`~sympy.solvers.ode.dsolve` may cause it to hang, because it will not attempt to simplify the Wronskian before integrating. It is recommended that you only use simplify=False with 'nth_linear_constant_coeff_variation_of_parameters_Integral' for this method, especially if the solution to the homogeneous equation has trigonometric functions in it. Examples ======== >>> from sympy import Function, dsolve, pprint, exp, log >>> from sympy.abc import x >>> f = Function('f') >>> pprint(dsolve(f(x).diff(x, 3) - 3*f(x).diff(x, 2) + ... 3*f(x).diff(x) - f(x) - exp(x)*log(x), f(x), ... hint='nth_linear_constant_coeff_variation_of_parameters')) / 3 \ | 2 x *(6*log(x) - 11)| x f(x) = |C1 + C2*x + C3*x + ------------------|*e \ 36 / References ========== - https://en.wikipedia.org/wiki/Variation_of_parameters - http://planetmath.org/VariationOfParameters - M. Tenenbaum & H. Pollard, "Ordinary Differential Equations", Dover 1963, pp. 233 # indirect doctest """ gensol = ode_nth_linear_constant_coeff_homogeneous(eq, func, order, match, returns='both') match.update(gensol) return _solve_variation_of_parameters(eq, func, order, match) def _solve_variation_of_parameters(eq, func, order, match): r""" Helper function for the method of variation of parameters and nonhomogeneous euler eq. See the :py:meth:`~sympy.solvers.ode.ode_nth_linear_constant_coeff_variation_of_parameters` docstring for more information on this method. The parameter ``match`` should be a dictionary that has the following keys: ``list`` A list of solutions to the homogeneous equation, such as the list returned by ``ode_nth_linear_constant_coeff_homogeneous(returns='list')``. ``sol`` The general solution, such as the solution returned by ``ode_nth_linear_constant_coeff_homogeneous(returns='sol')``. """ x = func.args[0] f = func.func r = match psol = 0 gensols = r['list'] gsol = r['sol'] wr = wronskian(gensols, x) if r.get('simplify', True): wr = simplify(wr) # We need much better simplification for # some ODEs. See issue 4662, for example. # To reduce commonly occurring sin(x)**2 + cos(x)**2 to 1 wr = trigsimp(wr, deep=True, recursive=True) if not wr: # The wronskian will be 0 iff the solutions are not linearly # independent. raise NotImplementedError("Cannot find " + str(order) + " solutions to the homogeneous equation necessary to apply " + "variation of parameters to " + str(eq) + " (Wronskian == 0)") if len(gensols) != order: raise NotImplementedError("Cannot find " + str(order) + " solutions to the homogeneous equation necessary to apply " + "variation of parameters to " + str(eq) + " (number of terms != order)") negoneterm = (-1)**(order) for i in gensols: psol += negoneterm*Integral(wronskian([sol for sol in gensols if sol != i], x)*r[-1]/wr, x)*i/r[order] negoneterm *= -1 if r.get('simplify', True): psol = simplify(psol) psol = trigsimp(psol, deep=True) return Eq(f(x), gsol.rhs + psol) def ode_separable(eq, func, order, match): r""" Solves separable 1st order differential equations. This is any differential equation that can be written as `P(y) \tfrac{dy}{dx} = Q(x)`. The solution can then just be found by rearranging terms and integrating: `\int P(y) \,dy = \int Q(x) \,dx`. This hint uses :py:meth:`sympy.simplify.simplify.separatevars` as its back end, so if a separable equation is not caught by this solver, it is most likely the fault of that function. :py:meth:`~sympy.simplify.simplify.separatevars` is smart enough to do most expansion and factoring necessary to convert a separable equation `F(x, y)` into the proper form `P(x)\cdot{}Q(y)`. The general solution is:: >>> from sympy import Function, dsolve, Eq, pprint >>> from sympy.abc import x >>> a, b, c, d, f = map(Function, ['a', 'b', 'c', 'd', 'f']) >>> genform = Eq(a(x)*b(f(x))*f(x).diff(x), c(x)*d(f(x))) >>> pprint(genform) d a(x)*b(f(x))*--(f(x)) = c(x)*d(f(x)) dx >>> pprint(dsolve(genform, f(x), hint='separable_Integral')) f(x) / / | | | b(y) | c(x) | ---- dy = C1 + | ---- dx | d(y) | a(x) | | / / Examples ======== >>> from sympy import Function, dsolve, Eq >>> from sympy.abc import x >>> f = Function('f') >>> pprint(dsolve(Eq(f(x)*f(x).diff(x) + x, 3*x*f(x)**2), f(x), ... hint='separable', simplify=False)) / 2 \ 2 log\3*f (x) - 1/ x ---------------- = C1 + -- 6 2 References ========== - M. Tenenbaum & H. Pollard, "Ordinary Differential Equations", Dover 1963, pp. 52 # indirect doctest """ x = func.args[0] f = func.func C1 = get_numbered_constants(eq, num=1) r = match # {'m1':m1, 'm2':m2, 'y':y} u = r.get('hint', f(x)) # get u from separable_reduced else get f(x) return Eq(Integral(r['m2']['coeff']*r['m2'][r['y']]/r['m1'][r['y']], (r['y'], None, u)), Integral(-r['m1']['coeff']*r['m1'][x]/ r['m2'][x], x) + C1) def checkinfsol(eq, infinitesimals, func=None, order=None): r""" This function is used to check if the given infinitesimals are the actual infinitesimals of the given first order differential equation. This method is specific to the Lie Group Solver of ODEs. As of now, it simply checks, by substituting the infinitesimals in the partial differential equation. .. math:: \frac{\partial \eta}{\partial x} + \left(\frac{\partial \eta}{\partial y} - \frac{\partial \xi}{\partial x}\right)*h - \frac{\partial \xi}{\partial y}*h^{2} - \xi\frac{\partial h}{\partial x} - \eta\frac{\partial h}{\partial y} = 0 where `\eta`, and `\xi` are the infinitesimals and `h(x,y) = \frac{dy}{dx}` The infinitesimals should be given in the form of a list of dicts ``[{xi(x, y): inf, eta(x, y): inf}]``, corresponding to the output of the function infinitesimals. It returns a list of values of the form ``[(True/False, sol)]`` where ``sol`` is the value obtained after substituting the infinitesimals in the PDE. If it is ``True``, then ``sol`` would be 0. """ if isinstance(eq, Equality): eq = eq.lhs - eq.rhs if not func: eq, func = _preprocess(eq) variables = func.args if len(variables) != 1: raise ValueError("ODE's have only one independent variable") else: x = variables[0] if not order: order = ode_order(eq, func) if order != 1: raise NotImplementedError("Lie groups solver has been implemented " "only for first order differential equations") else: df = func.diff(x) a = Wild('a', exclude = [df]) b = Wild('b', exclude = [df]) match = collect(expand(eq), df).match(a*df + b) if match: h = -simplify(match[b]/match[a]) else: try: sol = solve(eq, df) except NotImplementedError: raise NotImplementedError("Infinitesimals for the " "first order ODE could not be found") else: h = sol[0] # Find infinitesimals for one solution y = Dummy('y') h = h.subs(func, y) xi = Function('xi')(x, y) eta = Function('eta')(x, y) dxi = Function('xi')(x, func) deta = Function('eta')(x, func) pde = (eta.diff(x) + (eta.diff(y) - xi.diff(x))*h - (xi.diff(y))*h**2 - xi*(h.diff(x)) - eta*(h.diff(y))) soltup = [] for sol in infinitesimals: tsol = {xi: S(sol[dxi]).subs(func, y), eta: S(sol[deta]).subs(func, y)} sol = simplify(pde.subs(tsol).doit()) if sol: soltup.append((False, sol.subs(y, func))) else: soltup.append((True, 0)) return soltup def ode_lie_group(eq, func, order, match): r""" This hint implements the Lie group method of solving first order differential equations. The aim is to convert the given differential equation from the given coordinate given system into another coordinate system where it becomes invariant under the one-parameter Lie group of translations. The converted ODE is quadrature and can be solved easily. It makes use of the :py:meth:`sympy.solvers.ode.infinitesimals` function which returns the infinitesimals of the transformation. The coordinates `r` and `s` can be found by solving the following Partial Differential Equations. .. math :: \xi\frac{\partial r}{\partial x} + \eta\frac{\partial r}{\partial y} = 0 .. math :: \xi\frac{\partial s}{\partial x} + \eta\frac{\partial s}{\partial y} = 1 The differential equation becomes separable in the new coordinate system .. math :: \frac{ds}{dr} = \frac{\frac{\partial s}{\partial x} + h(x, y)\frac{\partial s}{\partial y}}{ \frac{\partial r}{\partial x} + h(x, y)\frac{\partial r}{\partial y}} After finding the solution by integration, it is then converted back to the original coordinate system by substituting `r` and `s` in terms of `x` and `y` again. Examples ======== >>> from sympy import Function, dsolve, Eq, exp, pprint >>> from sympy.abc import x >>> f = Function('f') >>> pprint(dsolve(f(x).diff(x) + 2*x*f(x) - x*exp(-x**2), f(x), ... hint='lie_group')) / 2\ 2 | x | -x f(x) = |C1 + --|*e \ 2 / References ========== - Solving differential equations by Symmetry Groups, John Starrett, pp. 1 - pp. 14 """ heuristics = lie_heuristics inf = {} f = func.func x = func.args[0] df = func.diff(x) xi = Function("xi") eta = Function("eta") a = Wild('a', exclude = [df]) b = Wild('b', exclude = [df]) xis = match.pop('xi') etas = match.pop('eta') if match: h = -simplify(match[match['d']]/match[match['e']]) y = match['y'] else: try: sol = solve(eq, df) if sol == []: raise NotImplementedError except NotImplementedError: raise NotImplementedError("Unable to solve the differential equation " + str(eq) + " by the lie group method") else: y = Dummy("y") h = sol[0].subs(func, y) if xis is not None and etas is not None: inf = [{xi(x, f(x)): S(xis), eta(x, f(x)): S(etas)}] if not checkinfsol(eq, inf, func=f(x), order=1)[0][0]: raise ValueError("The given infinitesimals xi and eta" " are not the infinitesimals to the given equation") else: heuristics = ["user_defined"] match = {'h': h, 'y': y} # This is done so that if: # a] solve raises a NotImplementedError. # b] any heuristic raises a ValueError # another heuristic can be used. tempsol = [] # Used by solve below for heuristic in heuristics: try: if not inf: inf = infinitesimals(eq, hint=heuristic, func=func, order=1, match=match) except ValueError: continue else: for infsim in inf: xiinf = (infsim[xi(x, func)]).subs(func, y) etainf = (infsim[eta(x, func)]).subs(func, y) # This condition creates recursion while using pdsolve. # Since the first step while solving a PDE of form # a*(f(x, y).diff(x)) + b*(f(x, y).diff(y)) + c = 0 # is to solve the ODE dy/dx = b/a if simplify(etainf/xiinf) == h: continue rpde = f(x, y).diff(x)*xiinf + f(x, y).diff(y)*etainf r = pdsolve(rpde, func=f(x, y)).rhs s = pdsolve(rpde - 1, func=f(x, y)).rhs newcoord = [_lie_group_remove(coord) for coord in [r, s]] r = Dummy("r") s = Dummy("s") C1 = Symbol("C1") rcoord = newcoord[0] scoord = newcoord[-1] try: sol = solve([r - rcoord, s - scoord], x, y, dict=True) except NotImplementedError: continue else: sol = sol[0] xsub = sol[x] ysub = sol[y] num = simplify(scoord.diff(x) + scoord.diff(y)*h) denom = simplify(rcoord.diff(x) + rcoord.diff(y)*h) if num and denom: diffeq = simplify((num/denom).subs([(x, xsub), (y, ysub)])) sep = separatevars(diffeq, symbols=[r, s], dict=True) if sep: # Trying to separate, r and s coordinates deq = integrate((1/sep[s]), s) + C1 - integrate(sep['coeff']*sep[r], r) # Substituting and reverting back to original coordinates deq = deq.subs([(r, rcoord), (s, scoord)]) try: sdeq = solve(deq, y) except NotImplementedError: tempsol.append(deq) else: if len(sdeq) == 1: return Eq(f(x), sdeq.pop()) else: return [Eq(f(x), sol) for sol in sdeq] elif denom: # (ds/dr) is zero which means s is constant return Eq(f(x), solve(scoord - C1, y)[0]) elif num: # (dr/ds) is zero which means r is constant return Eq(f(x), solve(rcoord - C1, y)[0]) # If nothing works, return solution as it is, without solving for y if tempsol: if len(tempsol) == 1: return Eq(tempsol.pop().subs(y, f(x)), 0) else: return [Eq(sol.subs(y, f(x)), 0) for sol in tempsol] raise NotImplementedError("The given ODE " + str(eq) + " cannot be solved by" + " the lie group method") def _lie_group_remove(coords): r""" This function is strictly meant for internal use by the Lie group ODE solving method. It replaces arbitrary functions returned by pdsolve with either 0 or 1 or the args of the arbitrary function. The algorithm used is: 1] If coords is an instance of an Undefined Function, then the args are returned 2] If the arbitrary function is present in an Add object, it is replaced by zero. 3] If the arbitrary function is present in an Mul object, it is replaced by one. 4] If coords has no Undefined Function, it is returned as it is. Examples ======== >>> from sympy.solvers.ode import _lie_group_remove >>> from sympy import Function >>> from sympy.abc import x, y >>> F = Function("F") >>> eq = x**2*y >>> _lie_group_remove(eq) x**2*y >>> eq = F(x**2*y) >>> _lie_group_remove(eq) x**2*y >>> eq = y**2*x + F(x**3) >>> _lie_group_remove(eq) x*y**2 >>> eq = (F(x**3) + y)*x**4 >>> _lie_group_remove(eq) x**4*y """ if isinstance(coords, AppliedUndef): return coords.args[0] elif coords.is_Add: subfunc = coords.atoms(AppliedUndef) if subfunc: for func in subfunc: coords = coords.subs(func, 0) return coords elif coords.is_Pow: base, expr = coords.as_base_exp() base = _lie_group_remove(base) expr = _lie_group_remove(expr) return base**expr elif coords.is_Mul: mulargs = [] coordargs = coords.args for arg in coordargs: if not isinstance(coords, AppliedUndef): mulargs.append(_lie_group_remove(arg)) return Mul(*mulargs) return coords def infinitesimals(eq, func=None, order=None, hint='default', match=None): r""" The infinitesimal functions of an ordinary differential equation, `\xi(x,y)` and `\eta(x,y)`, are the infinitesimals of the Lie group of point transformations for which the differential equation is invariant. So, the ODE `y'=f(x,y)` would admit a Lie group `x^*=X(x,y;\varepsilon)=x+\varepsilon\xi(x,y)`, `y^*=Y(x,y;\varepsilon)=y+\varepsilon\eta(x,y)` such that `(y^*)'=f(x^*, y^*)`. A change of coordinates, to `r(x,y)` and `s(x,y)`, can be performed so this Lie group becomes the translation group, `r^*=r` and `s^*=s+\varepsilon`. They are tangents to the coordinate curves of the new system. Consider the transformation `(x, y) \to (X, Y)` such that the differential equation remains invariant. `\xi` and `\eta` are the tangents to the transformed coordinates `X` and `Y`, at `\varepsilon=0`. .. math:: \left(\frac{\partial X(x,y;\varepsilon)}{\partial\varepsilon }\right)|_{\varepsilon=0} = \xi, \left(\frac{\partial Y(x,y;\varepsilon)}{\partial\varepsilon }\right)|_{\varepsilon=0} = \eta, The infinitesimals can be found by solving the following PDE: >>> from sympy import Function, diff, Eq, pprint >>> from sympy.abc import x, y >>> xi, eta, h = map(Function, ['xi', 'eta', 'h']) >>> h = h(x, y) # dy/dx = h >>> eta = eta(x, y) >>> xi = xi(x, y) >>> genform = Eq(eta.diff(x) + (eta.diff(y) - xi.diff(x))*h ... - (xi.diff(y))*h**2 - xi*(h.diff(x)) - eta*(h.diff(y)), 0) >>> pprint(genform) /d d \ d 2 d |--(eta(x, y)) - --(xi(x, y))|*h(x, y) - eta(x, y)*--(h(x, y)) - h (x, y)*--(x \dy dx / dy dy <BLANKLINE> d d i(x, y)) - xi(x, y)*--(h(x, y)) + --(eta(x, y)) = 0 dx dx Solving the above mentioned PDE is not trivial, and can be solved only by making intelligent assumptions for `\xi` and `\eta` (heuristics). Once an infinitesimal is found, the attempt to find more heuristics stops. This is done to optimise the speed of solving the differential equation. If a list of all the infinitesimals is needed, ``hint`` should be flagged as ``all``, which gives the complete list of infinitesimals. If the infinitesimals for a particular heuristic needs to be found, it can be passed as a flag to ``hint``. Examples ======== >>> from sympy import Function, diff >>> from sympy.solvers.ode import infinitesimals >>> from sympy.abc import x >>> f = Function('f') >>> eq = f(x).diff(x) - x**2*f(x) >>> infinitesimals(eq) [{eta(x, f(x)): exp(x**3/3), xi(x, f(x)): 0}] References ========== - Solving differential equations by Symmetry Groups, John Starrett, pp. 1 - pp. 14 """ if isinstance(eq, Equality): eq = eq.lhs - eq.rhs if not func: eq, func = _preprocess(eq) variables = func.args if len(variables) != 1: raise ValueError("ODE's have only one independent variable") else: x = variables[0] if not order: order = ode_order(eq, func) if order != 1: raise NotImplementedError("Infinitesimals for only " "first order ODE's have been implemented") else: df = func.diff(x) # Matching differential equation of the form a*df + b a = Wild('a', exclude = [df]) b = Wild('b', exclude = [df]) if match: # Used by lie_group hint h = match['h'] y = match['y'] else: match = collect(expand(eq), df).match(a*df + b) if match: h = -simplify(match[b]/match[a]) else: try: sol = solve(eq, df) except NotImplementedError: raise NotImplementedError("Infinitesimals for the " "first order ODE could not be found") else: h = sol[0] # Find infinitesimals for one solution y = Dummy("y") h = h.subs(func, y) u = Dummy("u") hx = h.diff(x) hy = h.diff(y) hinv = ((1/h).subs([(x, u), (y, x)])).subs(u, y) # Inverse ODE match = {'h': h, 'func': func, 'hx': hx, 'hy': hy, 'y': y, 'hinv': hinv} if hint == 'all': xieta = [] for heuristic in lie_heuristics: function = globals()['lie_heuristic_' + heuristic] inflist = function(match, comp=True) if inflist: xieta.extend([inf for inf in inflist if inf not in xieta]) if xieta: return xieta else: raise NotImplementedError("Infinitesimals could not be found for " "the given ODE") elif hint == 'default': for heuristic in lie_heuristics: function = globals()['lie_heuristic_' + heuristic] xieta = function(match, comp=False) if xieta: return xieta raise NotImplementedError("Infinitesimals could not be found for" " the given ODE") elif hint not in lie_heuristics: raise ValueError("Heuristic not recognized: " + hint) else: function = globals()['lie_heuristic_' + hint] xieta = function(match, comp=True) if xieta: return xieta else: raise ValueError("Infinitesimals could not be found using the" " given heuristic") def lie_heuristic_abaco1_simple(match, comp=False): r""" The first heuristic uses the following four sets of assumptions on `\xi` and `\eta` .. math:: \xi = 0, \eta = f(x) .. math:: \xi = 0, \eta = f(y) .. math:: \xi = f(x), \eta = 0 .. math:: \xi = f(y), \eta = 0 The success of this heuristic is determined by algebraic factorisation. For the first assumption `\xi = 0` and `\eta` to be a function of `x`, the PDE .. math:: \frac{\partial \eta}{\partial x} + (\frac{\partial \eta}{\partial y} - \frac{\partial \xi}{\partial x})*h - \frac{\partial \xi}{\partial y}*h^{2} - \xi*\frac{\partial h}{\partial x} - \eta*\frac{\partial h}{\partial y} = 0 reduces to `f'(x) - f\frac{\partial h}{\partial y} = 0` If `\frac{\partial h}{\partial y}` is a function of `x`, then this can usually be integrated easily. A similar idea is applied to the other 3 assumptions as well. References ========== - E.S Cheb-Terrab, L.G.S Duarte and L.A,C.P da Mota, Computer Algebra Solving of First Order ODEs Using Symmetry Methods, pp. 8 """ xieta = [] y = match['y'] h = match['h'] func = match['func'] x = func.args[0] hx = match['hx'] hy = match['hy'] xi = Function('xi')(x, func) eta = Function('eta')(x, func) hysym = hy.free_symbols if y not in hysym: try: fx = exp(integrate(hy, x)) except NotImplementedError: pass else: inf = {xi: S(0), eta: fx} if not comp: return [inf] if comp and inf not in xieta: xieta.append(inf) factor = hy/h facsym = factor.free_symbols if x not in facsym: try: fy = exp(integrate(factor, y)) except NotImplementedError: pass else: inf = {xi: S(0), eta: fy.subs(y, func)} if not comp: return [inf] if comp and inf not in xieta: xieta.append(inf) factor = -hx/h facsym = factor.free_symbols if y not in facsym: try: fx = exp(integrate(factor, x)) except NotImplementedError: pass else: inf = {xi: fx, eta: S(0)} if not comp: return [inf] if comp and inf not in xieta: xieta.append(inf) factor = -hx/(h**2) facsym = factor.free_symbols if x not in facsym: try: fy = exp(integrate(factor, y)) except NotImplementedError: pass else: inf = {xi: fy.subs(y, func), eta: S(0)} if not comp: return [inf] if comp and inf not in xieta: xieta.append(inf) if xieta: return xieta def lie_heuristic_abaco1_product(match, comp=False): r""" The second heuristic uses the following two assumptions on `\xi` and `\eta` .. math:: \eta = 0, \xi = f(x)*g(y) .. math:: \eta = f(x)*g(y), \xi = 0 The first assumption of this heuristic holds good if `\frac{1}{h^{2}}\frac{\partial^2}{\partial x \partial y}\log(h)` is separable in `x` and `y`, then the separated factors containing `x` is `f(x)`, and `g(y)` is obtained by .. math:: e^{\int f\frac{\partial}{\partial x}\left(\frac{1}{f*h}\right)\,dy} provided `f\frac{\partial}{\partial x}\left(\frac{1}{f*h}\right)` is a function of `y` only. The second assumption holds good if `\frac{dy}{dx} = h(x, y)` is rewritten as `\frac{dy}{dx} = \frac{1}{h(y, x)}` and the same properties of the first assumption satisfies. After obtaining `f(x)` and `g(y)`, the coordinates are again interchanged, to get `\eta` as `f(x)*g(y)` References ========== - E.S. Cheb-Terrab, A.D. Roche, Symmetries and First Order ODE Patterns, pp. 7 - pp. 8 """ xieta = [] y = match['y'] h = match['h'] hinv = match['hinv'] func = match['func'] x = func.args[0] xi = Function('xi')(x, func) eta = Function('eta')(x, func) inf = separatevars(((log(h).diff(y)).diff(x))/h**2, dict=True, symbols=[x, y]) if inf and inf['coeff']: fx = inf[x] gy = simplify(fx*((1/(fx*h)).diff(x))) gysyms = gy.free_symbols if x not in gysyms: gy = exp(integrate(gy, y)) inf = {eta: S(0), xi: (fx*gy).subs(y, func)} if not comp: return [inf] if comp and inf not in xieta: xieta.append(inf) u1 = Dummy("u1") inf = separatevars(((log(hinv).diff(y)).diff(x))/hinv**2, dict=True, symbols=[x, y]) if inf and inf['coeff']: fx = inf[x] gy = simplify(fx*((1/(fx*hinv)).diff(x))) gysyms = gy.free_symbols if x not in gysyms: gy = exp(integrate(gy, y)) etaval = fx*gy etaval = (etaval.subs([(x, u1), (y, x)])).subs(u1, y) inf = {eta: etaval.subs(y, func), xi: S(0)} if not comp: return [inf] if comp and inf not in xieta: xieta.append(inf) if xieta: return xieta def lie_heuristic_bivariate(match, comp=False): r""" The third heuristic assumes the infinitesimals `\xi` and `\eta` to be bi-variate polynomials in `x` and `y`. The assumption made here for the logic below is that `h` is a rational function in `x` and `y` though that may not be necessary for the infinitesimals to be bivariate polynomials. The coefficients of the infinitesimals are found out by substituting them in the PDE and grouping similar terms that are polynomials and since they form a linear system, solve and check for non trivial solutions. The degree of the assumed bivariates are increased till a certain maximum value. References ========== - Lie Groups and Differential Equations pp. 327 - pp. 329 """ h = match['h'] hx = match['hx'] hy = match['hy'] func = match['func'] x = func.args[0] y = match['y'] xi = Function('xi')(x, func) eta = Function('eta')(x, func) if h.is_rational_function(): # The maximum degree that the infinitesimals can take is # calculated by this technique. etax, etay, etad, xix, xiy, xid = symbols("etax etay etad xix xiy xid") ipde = etax + (etay - xix)*h - xiy*h**2 - xid*hx - etad*hy num, denom = cancel(ipde).as_numer_denom() deg = Poly(num, x, y).total_degree() deta = Function('deta')(x, y) dxi = Function('dxi')(x, y) ipde = (deta.diff(x) + (deta.diff(y) - dxi.diff(x))*h - (dxi.diff(y))*h**2 - dxi*hx - deta*hy) xieq = Symbol("xi0") etaeq = Symbol("eta0") for i in range(deg + 1): if i: xieq += Add(*[ Symbol("xi_" + str(power) + "_" + str(i - power))*x**power*y**(i - power) for power in range(i + 1)]) etaeq += Add(*[ Symbol("eta_" + str(power) + "_" + str(i - power))*x**power*y**(i - power) for power in range(i + 1)]) pden, denom = (ipde.subs({dxi: xieq, deta: etaeq}).doit()).as_numer_denom() pden = expand(pden) # If the individual terms are monomials, the coefficients # are grouped if pden.is_polynomial(x, y) and pden.is_Add: polyy = Poly(pden, x, y).as_dict() if polyy: symset = xieq.free_symbols.union(etaeq.free_symbols) - {x, y} soldict = solve(polyy.values(), *symset) if isinstance(soldict, list): soldict = soldict[0] if any(x for x in soldict.values()): xired = xieq.subs(soldict) etared = etaeq.subs(soldict) # Scaling is done by substituting one for the parameters # This can be any number except zero. dict_ = dict((sym, 1) for sym in symset) inf = {eta: etared.subs(dict_).subs(y, func), xi: xired.subs(dict_).subs(y, func)} return [inf] def lie_heuristic_chi(match, comp=False): r""" The aim of the fourth heuristic is to find the function `\chi(x, y)` that satisfies the PDE `\frac{d\chi}{dx} + h\frac{d\chi}{dx} - \frac{\partial h}{\partial y}\chi = 0`. This assumes `\chi` to be a bivariate polynomial in `x` and `y`. By intuition, `h` should be a rational function in `x` and `y`. The method used here is to substitute a general binomial for `\chi` up to a certain maximum degree is reached. The coefficients of the polynomials, are calculated by by collecting terms of the same order in `x` and `y`. After finding `\chi`, the next step is to use `\eta = \xi*h + \chi`, to determine `\xi` and `\eta`. This can be done by dividing `\chi` by `h` which would give `-\xi` as the quotient and `\eta` as the remainder. References ========== - E.S Cheb-Terrab, L.G.S Duarte and L.A,C.P da Mota, Computer Algebra Solving of First Order ODEs Using Symmetry Methods, pp. 8 """ h = match['h'] hx = match['hx'] hy = match['hy'] func = match['func'] x = func.args[0] y = match['y'] xi = Function('xi')(x, func) eta = Function('eta')(x, func) if h.is_rational_function(): schi, schix, schiy = symbols("schi, schix, schiy") cpde = schix + h*schiy - hy*schi num, denom = cancel(cpde).as_numer_denom() deg = Poly(num, x, y).total_degree() chi = Function('chi')(x, y) chix = chi.diff(x) chiy = chi.diff(y) cpde = chix + h*chiy - hy*chi chieq = Symbol("chi") for i in range(1, deg + 1): chieq += Add(*[ Symbol("chi_" + str(power) + "_" + str(i - power))*x**power*y**(i - power) for power in range(i + 1)]) cnum, cden = cancel(cpde.subs({chi : chieq}).doit()).as_numer_denom() cnum = expand(cnum) if cnum.is_polynomial(x, y) and cnum.is_Add: cpoly = Poly(cnum, x, y).as_dict() if cpoly: solsyms = chieq.free_symbols - {x, y} soldict = solve(cpoly.values(), *solsyms) if isinstance(soldict, list): soldict = soldict[0] if any(x for x in soldict.values()): chieq = chieq.subs(soldict) dict_ = dict((sym, 1) for sym in solsyms) chieq = chieq.subs(dict_) # After finding chi, the main aim is to find out # eta, xi by the equation eta = xi*h + chi # One method to set xi, would be rearranging it to # (eta/h) - xi = (chi/h). This would mean dividing # chi by h would give -xi as the quotient and eta # as the remainder. Thanks to Sean Vig for suggesting # this method. xic, etac = div(chieq, h) inf = {eta: etac.subs(y, func), xi: -xic.subs(y, func)} return [inf] def lie_heuristic_function_sum(match, comp=False): r""" This heuristic uses the following two assumptions on `\xi` and `\eta` .. math:: \eta = 0, \xi = f(x) + g(y) .. math:: \eta = f(x) + g(y), \xi = 0 The first assumption of this heuristic holds good if .. math:: \frac{\partial}{\partial y}[(h\frac{\partial^{2}}{ \partial x^{2}}(h^{-1}))^{-1}] is separable in `x` and `y`, 1. The separated factors containing `y` is `\frac{\partial g}{\partial y}`. From this `g(y)` can be determined. 2. The separated factors containing `x` is `f''(x)`. 3. `h\frac{\partial^{2}}{\partial x^{2}}(h^{-1})` equals `\frac{f''(x)}{f(x) + g(y)}`. From this `f(x)` can be determined. The second assumption holds good if `\frac{dy}{dx} = h(x, y)` is rewritten as `\frac{dy}{dx} = \frac{1}{h(y, x)}` and the same properties of the first assumption satisfies. After obtaining `f(x)` and `g(y)`, the coordinates are again interchanged, to get `\eta` as `f(x) + g(y)`. For both assumptions, the constant factors are separated among `g(y)` and `f''(x)`, such that `f''(x)` obtained from 3] is the same as that obtained from 2]. If not possible, then this heuristic fails. References ========== - E.S. Cheb-Terrab, A.D. Roche, Symmetries and First Order ODE Patterns, pp. 7 - pp. 8 """ xieta = [] h = match['h'] hx = match['hx'] hy = match['hy'] func = match['func'] hinv = match['hinv'] x = func.args[0] y = match['y'] xi = Function('xi')(x, func) eta = Function('eta')(x, func) for odefac in [h, hinv]: factor = odefac*((1/odefac).diff(x, 2)) sep = separatevars((1/factor).diff(y), dict=True, symbols=[x, y]) if sep and sep['coeff'] and sep[x].has(x) and sep[y].has(y): k = Dummy("k") try: gy = k*integrate(sep[y], y) except NotImplementedError: pass else: fdd = 1/(k*sep[x]*sep['coeff']) fx = simplify(fdd/factor - gy) check = simplify(fx.diff(x, 2) - fdd) if fx: if not check: fx = fx.subs(k, 1) gy = (gy/k) else: sol = solve(check, k) if sol: sol = sol[0] fx = fx.subs(k, sol) gy = (gy/k)*sol else: continue if odefac == hinv: # Inverse ODE fx = fx.subs(x, y) gy = gy.subs(y, x) etaval = factor_terms(fx + gy) if etaval.is_Mul: etaval = Mul(*[arg for arg in etaval.args if arg.has(x, y)]) if odefac == hinv: # Inverse ODE inf = {eta: etaval.subs(y, func), xi : S(0)} else: inf = {xi: etaval.subs(y, func), eta : S(0)} if not comp: return [inf] else: xieta.append(inf) if xieta: return xieta def lie_heuristic_abaco2_similar(match, comp=False): r""" This heuristic uses the following two assumptions on `\xi` and `\eta` .. math:: \eta = g(x), \xi = f(x) .. math:: \eta = f(y), \xi = g(y) For the first assumption, 1. First `\frac{\frac{\partial h}{\partial y}}{\frac{\partial^{2} h}{ \partial yy}}` is calculated. Let us say this value is A 2. If this is constant, then `h` is matched to the form `A(x) + B(x)e^{ \frac{y}{C}}` then, `\frac{e^{\int \frac{A(x)}{C} \,dx}}{B(x)}` gives `f(x)` and `A(x)*f(x)` gives `g(x)` 3. Otherwise `\frac{\frac{\partial A}{\partial X}}{\frac{\partial A}{ \partial Y}} = \gamma` is calculated. If a] `\gamma` is a function of `x` alone b] `\frac{\gamma\frac{\partial h}{\partial y} - \gamma'(x) - \frac{ \partial h}{\partial x}}{h + \gamma} = G` is a function of `x` alone. then, `e^{\int G \,dx}` gives `f(x)` and `-\gamma*f(x)` gives `g(x)` The second assumption holds good if `\frac{dy}{dx} = h(x, y)` is rewritten as `\frac{dy}{dx} = \frac{1}{h(y, x)}` and the same properties of the first assumption satisfies. After obtaining `f(x)` and `g(x)`, the coordinates are again interchanged, to get `\xi` as `f(x^*)` and `\eta` as `g(y^*)` References ========== - E.S. Cheb-Terrab, A.D. Roche, Symmetries and First Order ODE Patterns, pp. 10 - pp. 12 """ xieta = [] h = match['h'] hx = match['hx'] hy = match['hy'] func = match['func'] hinv = match['hinv'] x = func.args[0] y = match['y'] xi = Function('xi')(x, func) eta = Function('eta')(x, func) factor = cancel(h.diff(y)/h.diff(y, 2)) factorx = factor.diff(x) factory = factor.diff(y) if not factor.has(x) and not factor.has(y): A = Wild('A', exclude=[y]) B = Wild('B', exclude=[y]) C = Wild('C', exclude=[x, y]) match = h.match(A + B*exp(y/C)) try: tau = exp(-integrate(match[A]/match[C]), x)/match[B] except NotImplementedError: pass else: gx = match[A]*tau return [{xi: tau, eta: gx}] else: gamma = cancel(factorx/factory) if not gamma.has(y): tauint = cancel((gamma*hy - gamma.diff(x) - hx)/(h + gamma)) if not tauint.has(y): try: tau = exp(integrate(tauint, x)) except NotImplementedError: pass else: gx = -tau*gamma return [{xi: tau, eta: gx}] factor = cancel(hinv.diff(y)/hinv.diff(y, 2)) factorx = factor.diff(x) factory = factor.diff(y) if not factor.has(x) and not factor.has(y): A = Wild('A', exclude=[y]) B = Wild('B', exclude=[y]) C = Wild('C', exclude=[x, y]) match = h.match(A + B*exp(y/C)) try: tau = exp(-integrate(match[A]/match[C]), x)/match[B] except NotImplementedError: pass else: gx = match[A]*tau return [{eta: tau.subs(x, func), xi: gx.subs(x, func)}] else: gamma = cancel(factorx/factory) if not gamma.has(y): tauint = cancel((gamma*hinv.diff(y) - gamma.diff(x) - hinv.diff(x))/( hinv + gamma)) if not tauint.has(y): try: tau = exp(integrate(tauint, x)) except NotImplementedError: pass else: gx = -tau*gamma return [{eta: tau.subs(x, func), xi: gx.subs(x, func)}] def lie_heuristic_abaco2_unique_unknown(match, comp=False): r""" This heuristic assumes the presence of unknown functions or known functions with non-integer powers. 1. A list of all functions and non-integer powers containing x and y 2. Loop over each element `f` in the list, find `\frac{\frac{\partial f}{\partial x}}{ \frac{\partial f}{\partial x}} = R` If it is separable in `x` and `y`, let `X` be the factors containing `x`. Then a] Check if `\xi = X` and `\eta = -\frac{X}{R}` satisfy the PDE. If yes, then return `\xi` and `\eta` b] Check if `\xi = \frac{-R}{X}` and `\eta = -\frac{1}{X}` satisfy the PDE. If yes, then return `\xi` and `\eta` If not, then check if a] :math:`\xi = -R,\eta = 1` b] :math:`\xi = 1, \eta = -\frac{1}{R}` are solutions. References ========== - E.S. Cheb-Terrab, A.D. Roche, Symmetries and First Order ODE Patterns, pp. 10 - pp. 12 """ xieta = [] h = match['h'] hx = match['hx'] hy = match['hy'] func = match['func'] hinv = match['hinv'] x = func.args[0] y = match['y'] xi = Function('xi')(x, func) eta = Function('eta')(x, func) funclist = [] for atom in h.atoms(Pow): base, exp = atom.as_base_exp() if base.has(x) and base.has(y): if not exp.is_Integer: funclist.append(atom) for function in h.atoms(AppliedUndef): syms = function.free_symbols if x in syms and y in syms: funclist.append(function) for f in funclist: frac = cancel(f.diff(y)/f.diff(x)) sep = separatevars(frac, dict=True, symbols=[x, y]) if sep and sep['coeff']: xitry1 = sep[x] etatry1 = -1/(sep[y]*sep['coeff']) pde1 = etatry1.diff(y)*h - xitry1.diff(x)*h - xitry1*hx - etatry1*hy if not simplify(pde1): return [{xi: xitry1, eta: etatry1.subs(y, func)}] xitry2 = 1/etatry1 etatry2 = 1/xitry1 pde2 = etatry2.diff(x) - (xitry2.diff(y))*h**2 - xitry2*hx - etatry2*hy if not simplify(expand(pde2)): return [{xi: xitry2.subs(y, func), eta: etatry2}] else: etatry = -1/frac pde = etatry.diff(x) + etatry.diff(y)*h - hx - etatry*hy if not simplify(pde): return [{xi: S(1), eta: etatry.subs(y, func)}] xitry = -frac pde = -xitry.diff(x)*h -xitry.diff(y)*h**2 - xitry*hx -hy if not simplify(expand(pde)): return [{xi: xitry.subs(y, func), eta: S(1)}] def lie_heuristic_abaco2_unique_general(match, comp=False): r""" This heuristic finds if infinitesimals of the form `\eta = f(x)`, `\xi = g(y)` without making any assumptions on `h`. The complete sequence of steps is given in the paper mentioned below. References ========== - E.S. Cheb-Terrab, A.D. Roche, Symmetries and First Order ODE Patterns, pp. 10 - pp. 12 """ xieta = [] h = match['h'] hx = match['hx'] hy = match['hy'] func = match['func'] hinv = match['hinv'] x = func.args[0] y = match['y'] xi = Function('xi')(x, func) eta = Function('eta')(x, func) C = S(0) A = hx.diff(y) B = hy.diff(y) + hy**2 C = hx.diff(x) - hx**2 if not (A and B and C): return Ax = A.diff(x) Ay = A.diff(y) Axy = Ax.diff(y) Axx = Ax.diff(x) Ayy = Ay.diff(y) D = simplify(2*Axy + hx*Ay - Ax*hy + (hx*hy + 2*A)*A)*A - 3*Ax*Ay if not D: E1 = simplify(3*Ax**2 + ((hx**2 + 2*C)*A - 2*Axx)*A) if E1: E2 = simplify((2*Ayy + (2*B - hy**2)*A)*A - 3*Ay**2) if not E2: E3 = simplify( E1*((28*Ax + 4*hx*A)*A**3 - E1*(hy*A + Ay)) - E1.diff(x)*8*A**4) if not E3: etaval = cancel((4*A**3*(Ax - hx*A) + E1*(hy*A - Ay))/(S(2)*A*E1)) if x not in etaval: try: etaval = exp(integrate(etaval, y)) except NotImplementedError: pass else: xival = -4*A**3*etaval/E1 if y not in xival: return [{xi: xival, eta: etaval.subs(y, func)}] else: E1 = simplify((2*Ayy + (2*B - hy**2)*A)*A - 3*Ay**2) if E1: E2 = simplify( 4*A**3*D - D**2 + E1*((2*Axx - (hx**2 + 2*C)*A)*A - 3*Ax**2)) if not E2: E3 = simplify( -(A*D)*E1.diff(y) + ((E1.diff(x) - hy*D)*A + 3*Ay*D + (A*hx - 3*Ax)*E1)*E1) if not E3: etaval = cancel(((A*hx - Ax)*E1 - (Ay + A*hy)*D)/(S(2)*A*D)) if x not in etaval: try: etaval = exp(integrate(etaval, y)) except NotImplementedError: pass else: xival = -E1*etaval/D if y not in xival: return [{xi: xival, eta: etaval.subs(y, func)}] def lie_heuristic_linear(match, comp=False): r""" This heuristic assumes 1. `\xi = ax + by + c` and 2. `\eta = fx + gy + h` After substituting the following assumptions in the determining PDE, it reduces to .. math:: f + (g - a)h - bh^{2} - (ax + by + c)\frac{\partial h}{\partial x} - (fx + gy + c)\frac{\partial h}{\partial y} Solving the reduced PDE obtained, using the method of characteristics, becomes impractical. The method followed is grouping similar terms and solving the system of linear equations obtained. The difference between the bivariate heuristic is that `h` need not be a rational function in this case. References ========== - E.S. Cheb-Terrab, A.D. Roche, Symmetries and First Order ODE Patterns, pp. 10 - pp. 12 """ xieta = [] h = match['h'] hx = match['hx'] hy = match['hy'] func = match['func'] hinv = match['hinv'] x = func.args[0] y = match['y'] xi = Function('xi')(x, func) eta = Function('eta')(x, func) coeffdict = {} symbols = numbered_symbols("c", cls=Dummy) symlist = [next(symbols) for i in islice(symbols, 6)] C0, C1, C2, C3, C4, C5 = symlist pde = C3 + (C4 - C0)*h -(C0*x + C1*y + C2)*hx - (C3*x + C4*y + C5)*hy - C1*h**2 pde, denom = pde.as_numer_denom() pde = powsimp(expand(pde)) if pde.is_Add: terms = pde.args for term in terms: if term.is_Mul: rem = Mul(*[m for m in term.args if not m.has(x, y)]) xypart = term/rem if xypart not in coeffdict: coeffdict[xypart] = rem else: coeffdict[xypart] += rem else: if term not in coeffdict: coeffdict[term] = S(1) else: coeffdict[term] += S(1) sollist = coeffdict.values() soldict = solve(sollist, symlist) if soldict: if isinstance(soldict, list): soldict = soldict[0] subval = soldict.values() if any(t for t in subval): onedict = dict(zip(symlist, [1]*6)) xival = C0*x + C1*func + C2 etaval = C3*x + C4*func + C5 xival = xival.subs(soldict) etaval = etaval.subs(soldict) xival = xival.subs(onedict) etaval = etaval.subs(onedict) return [{xi: xival, eta: etaval}] def sysode_linear_2eq_order1(match_): x = match_['func'][0].func y = match_['func'][1].func func = match_['func'] fc = match_['func_coeff'] eq = match_['eq'] C1, C2, C3, C4 = get_numbered_constants(eq, num=4) r = dict() t = list(list(eq[0].atoms(Derivative))[0].atoms(Symbol))[0] for i in range(2): eqs = 0 for terms in Add.make_args(eq[i]): eqs += terms/fc[i,func[i],1] eq[i] = eqs # for equations Eq(a1*diff(x(t),t), a*x(t) + b*y(t) + k1) # and Eq(a2*diff(x(t),t), c*x(t) + d*y(t) + k2) r['a'] = -fc[0,x(t),0]/fc[0,x(t),1] r['c'] = -fc[1,x(t),0]/fc[1,y(t),1] r['b'] = -fc[0,y(t),0]/fc[0,x(t),1] r['d'] = -fc[1,y(t),0]/fc[1,y(t),1] forcing = [S(0),S(0)] for i in range(2): for j in Add.make_args(eq[i]): if not j.has(x(t), y(t)): forcing[i] += j if not (forcing[0].has(t) or forcing[1].has(t)): r['k1'] = forcing[0] r['k2'] = forcing[1] else: raise NotImplementedError("Only homogeneous problems are supported" + " (and constant inhomogeneity)") if match_['type_of_equation'] == 'type1': sol = _linear_2eq_order1_type1(x, y, t, r, eq) if match_['type_of_equation'] == 'type2': gsol = _linear_2eq_order1_type1(x, y, t, r, eq) psol = _linear_2eq_order1_type2(x, y, t, r, eq) sol = [Eq(x(t), gsol[0].rhs+psol[0]), Eq(y(t), gsol[1].rhs+psol[1])] if match_['type_of_equation'] == 'type3': sol = _linear_2eq_order1_type3(x, y, t, r, eq) if match_['type_of_equation'] == 'type4': sol = _linear_2eq_order1_type4(x, y, t, r, eq) if match_['type_of_equation'] == 'type5': sol = _linear_2eq_order1_type5(x, y, t, r, eq) if match_['type_of_equation'] == 'type6': sol = _linear_2eq_order1_type6(x, y, t, r, eq) if match_['type_of_equation'] == 'type7': sol = _linear_2eq_order1_type7(x, y, t, r, eq) return sol def _linear_2eq_order1_type1(x, y, t, r, eq): r""" It is classified under system of two linear homogeneous first-order constant-coefficient ordinary differential equations. The equations which come under this type are .. math:: x' = ax + by, .. math:: y' = cx + dy The characteristics equation is written as .. math:: \lambda^{2} + (a+d) \lambda + ad - bc = 0 and its discriminant is `D = (a-d)^{2} + 4bc`. There are several cases 1. Case when `ad - bc \neq 0`. The origin of coordinates, `x = y = 0`, is the only stationary point; it is - a node if `D = 0` - a node if `D > 0` and `ad - bc > 0` - a saddle if `D > 0` and `ad - bc < 0` - a focus if `D < 0` and `a + d \neq 0` - a centre if `D < 0` and `a + d \neq 0`. 1.1. If `D > 0`. The characteristic equation has two distinct real roots `\lambda_1` and `\lambda_ 2` . The general solution of the system in question is expressed as .. math:: x = C_1 b e^{\lambda_1 t} + C_2 b e^{\lambda_2 t} .. math:: y = C_1 (\lambda_1 - a) e^{\lambda_1 t} + C_2 (\lambda_2 - a) e^{\lambda_2 t} where `C_1` and `C_2` being arbitrary constants 1.2. If `D < 0`. The characteristics equation has two conjugate roots, `\lambda_1 = \sigma + i \beta` and `\lambda_2 = \sigma - i \beta`. The general solution of the system is given by .. math:: x = b e^{\sigma t} (C_1 \sin(\beta t) + C_2 \cos(\beta t)) .. math:: y = e^{\sigma t} ([(\sigma - a) C_1 - \beta C_2] \sin(\beta t) + [\beta C_1 + (\sigma - a) C_2 \cos(\beta t)]) 1.3. If `D = 0` and `a \neq d`. The characteristic equation has two equal roots, `\lambda_1 = \lambda_2`. The general solution of the system is written as .. math:: x = 2b (C_1 + \frac{C_2}{a-d} + C_2 t) e^{\frac{a+d}{2} t} .. math:: y = [(d - a) C_1 + C_2 + (d - a) C_2 t] e^{\frac{a+d}{2} t} 1.4. If `D = 0` and `a = d \neq 0` and `b = 0` .. math:: x = C_1 e^{a t} , y = (c C_1 t + C_2) e^{a t} 1.5. If `D = 0` and `a = d \neq 0` and `c = 0` .. math:: x = (b C_1 t + C_2) e^{a t} , y = C_1 e^{a t} 2. Case when `ad - bc = 0` and `a^{2} + b^{2} > 0`. The whole straight line `ax + by = 0` consists of singular points. The original system of differential equations can be rewritten as .. math:: x' = ax + by , y' = k (ax + by) 2.1 If `a + bk \neq 0`, solution will be .. math:: x = b C_1 + C_2 e^{(a + bk) t} , y = -a C_1 + k C_2 e^{(a + bk) t} 2.2 If `a + bk = 0`, solution will be .. math:: x = C_1 (bk t - 1) + b C_2 t , y = k^{2} b C_1 t + (b k^{2} t + 1) C_2 """ l = Dummy('l') C1, C2 = get_numbered_constants(eq, num=2) a, b, c, d = r['a'], r['b'], r['c'], r['d'] real_coeff = all(v.is_real for v in (a, b, c, d)) D = (a - d)**2 + 4*b*c l1 = (a + d + sqrt(D))/2 l2 = (a + d - sqrt(D))/2 equal_roots = Eq(D, 0).expand() gsol1, gsol2 = [], [] # Solutions have exponential form if either D > 0 with real coefficients # or D != 0 with complex coefficients. Eigenvalues are distinct. # For each eigenvalue lam, pick an eigenvector, making sure we don't get (0, 0) # The candidates are (b, lam-a) and (lam-d, c). exponential_form = D > 0 if real_coeff else Not(equal_roots) bad_ab_vector1 = And(Eq(b, 0), Eq(l1, a)) bad_ab_vector2 = And(Eq(b, 0), Eq(l2, a)) vector1 = Matrix((Piecewise((l1 - d, bad_ab_vector1), (b, True)), Piecewise((c, bad_ab_vector1), (l1 - a, True)))) vector2 = Matrix((Piecewise((l2 - d, bad_ab_vector2), (b, True)), Piecewise((c, bad_ab_vector2), (l2 - a, True)))) sol_vector = C1*exp(l1*t)*vector1 + C2*exp(l2*t)*vector2 gsol1.append((sol_vector[0], exponential_form)) gsol2.append((sol_vector[1], exponential_form)) # Solutions have trigonometric form for real coefficients with D < 0 # Both b and c are nonzero in this case, so (b, lam-a) is an eigenvector # It splits into real/imag parts as (b, sigma-a) and (0, beta). Then # multiply it by C1(cos(beta*t) + I*C2*sin(beta*t)) and separate real/imag trigonometric_form = D < 0 if real_coeff else False sigma = re(l1) if im(l1).is_positive: beta = im(l1) else: beta = im(l2) vector1 = Matrix((b, sigma - a)) vector2 = Matrix((0, beta)) sol_vector = exp(sigma*t) * (C1*(cos(beta*t)*vector1 - sin(beta*t)*vector2) + \ C2*(sin(beta*t)*vector1 + cos(beta*t)*vector2)) gsol1.append((sol_vector[0], trigonometric_form)) gsol2.append((sol_vector[1], trigonometric_form)) # Final case is D == 0, a single eigenvalue. If the eigenspace is 2-dimensional # then we have a scalar matrix, deal with this case first. scalar_matrix = And(Eq(a, d), Eq(b, 0), Eq(c, 0)) vector1 = Matrix((S.One, S.Zero)) vector2 = Matrix((S.Zero, S.One)) sol_vector = exp(l1*t) * (C1*vector1 + C2*vector2) gsol1.append((sol_vector[0], scalar_matrix)) gsol2.append((sol_vector[1], scalar_matrix)) # Have one eigenvector. Get a generalized eigenvector from (A-lam)*vector2 = vector1 vector1 = Matrix((Piecewise((l1 - d, bad_ab_vector1), (b, True)), Piecewise((c, bad_ab_vector1), (l1 - a, True)))) vector2 = Matrix((Piecewise((S.One, bad_ab_vector1), (S.Zero, Eq(a, l1)), (b/(a - l1), True)), Piecewise((S.Zero, bad_ab_vector1), (S.One, Eq(a, l1)), (S.Zero, True)))) sol_vector = exp(l1*t) * (C1*vector1 + C2*(vector2 + t*vector1)) gsol1.append((sol_vector[0], equal_roots)) gsol2.append((sol_vector[1], equal_roots)) return [Eq(x(t), Piecewise(*gsol1)), Eq(y(t), Piecewise(*gsol2))] def _linear_2eq_order1_type2(x, y, t, r, eq): r""" The equations of this type are .. math:: x' = ax + by + k1 , y' = cx + dy + k2 The general solution of this system is given by sum of its particular solution and the general solution of the corresponding homogeneous system is obtained from type1. 1. When `ad - bc \neq 0`. The particular solution will be `x = x_0` and `y = y_0` where `x_0` and `y_0` are determined by solving linear system of equations .. math:: a x_0 + b y_0 + k1 = 0 , c x_0 + d y_0 + k2 = 0 2. When `ad - bc = 0` and `a^{2} + b^{2} > 0`. In this case, the system of equation becomes .. math:: x' = ax + by + k_1 , y' = k (ax + by) + k_2 2.1 If `\sigma = a + bk \neq 0`, particular solution is given by .. math:: x = b \sigma^{-1} (c_1 k - c_2) t - \sigma^{-2} (a c_1 + b c_2) .. math:: y = kx + (c_2 - c_1 k) t 2.2 If `\sigma = a + bk = 0`, particular solution is given by .. math:: x = \frac{1}{2} b (c_2 - c_1 k) t^{2} + c_1 t .. math:: y = kx + (c_2 - c_1 k) t """ r['k1'] = -r['k1']; r['k2'] = -r['k2'] if (r['a']*r['d'] - r['b']*r['c']) != 0: x0, y0 = symbols('x0, y0', cls=Dummy) sol = solve((r['a']*x0+r['b']*y0+r['k1'], r['c']*x0+r['d']*y0+r['k2']), x0, y0) psol = [sol[x0], sol[y0]] elif (r['a']*r['d'] - r['b']*r['c']) == 0 and (r['a']**2+r['b']**2) > 0: k = r['c']/r['a'] sigma = r['a'] + r['b']*k if sigma != 0: sol1 = r['b']*sigma**-1*(r['k1']*k-r['k2'])*t - sigma**-2*(r['a']*r['k1']+r['b']*r['k2']) sol2 = k*sol1 + (r['k2']-r['k1']*k)*t else: # FIXME: a previous typo fix shows this is not covered by tests sol1 = r['b']*(r['k2']-r['k1']*k)*t**2 + r['k1']*t sol2 = k*sol1 + (r['k2']-r['k1']*k)*t psol = [sol1, sol2] return psol def _linear_2eq_order1_type3(x, y, t, r, eq): r""" The equations of this type of ode are .. math:: x' = f(t) x + g(t) y .. math:: y' = g(t) x + f(t) y The solution of such equations is given by .. math:: x = e^{F} (C_1 e^{G} + C_2 e^{-G}) , y = e^{F} (C_1 e^{G} - C_2 e^{-G}) where `C_1` and `C_2` are arbitrary constants, and .. math:: F = \int f(t) \,dt , G = \int g(t) \,dt """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) F = Integral(r['a'], t) G = Integral(r['b'], t) sol1 = exp(F)*(C1*exp(G) + C2*exp(-G)) sol2 = exp(F)*(C1*exp(G) - C2*exp(-G)) return [Eq(x(t), sol1), Eq(y(t), sol2)] def _linear_2eq_order1_type4(x, y, t, r, eq): r""" The equations of this type of ode are . .. math:: x' = f(t) x + g(t) y .. math:: y' = -g(t) x + f(t) y The solution is given by .. math:: x = F (C_1 \cos(G) + C_2 \sin(G)), y = F (-C_1 \sin(G) + C_2 \cos(G)) where `C_1` and `C_2` are arbitrary constants, and .. math:: F = \int f(t) \,dt , G = \int g(t) \,dt """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) if r['b'] == -r['c']: F = exp(Integral(r['a'], t)) G = Integral(r['b'], t) sol1 = F*(C1*cos(G) + C2*sin(G)) sol2 = F*(-C1*sin(G) + C2*cos(G)) elif r['d'] == -r['a']: F = exp(Integral(r['c'], t)) G = Integral(r['d'], t) sol1 = F*(-C1*sin(G) + C2*cos(G)) sol2 = F*(C1*cos(G) + C2*sin(G)) return [Eq(x(t), sol1), Eq(y(t), sol2)] def _linear_2eq_order1_type5(x, y, t, r, eq): r""" The equations of this type of ode are . .. math:: x' = f(t) x + g(t) y .. math:: y' = a g(t) x + [f(t) + b g(t)] y The transformation of .. math:: x = e^{\int f(t) \,dt} u , y = e^{\int f(t) \,dt} v , T = \int g(t) \,dt leads to a system of constant coefficient linear differential equations .. math:: u'(T) = v , v'(T) = au + bv """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) u, v = symbols('u, v', cls=Function) T = Symbol('T') if not cancel(r['c']/r['b']).has(t): p = cancel(r['c']/r['b']) q = cancel((r['d']-r['a'])/r['b']) eq = (Eq(diff(u(T),T), v(T)), Eq(diff(v(T),T), p*u(T)+q*v(T))) sol = dsolve(eq) sol1 = exp(Integral(r['a'], t))*sol[0].rhs.subs(T, Integral(r['b'],t)) sol2 = exp(Integral(r['a'], t))*sol[1].rhs.subs(T, Integral(r['b'],t)) if not cancel(r['a']/r['d']).has(t): p = cancel(r['a']/r['d']) q = cancel((r['b']-r['c'])/r['d']) sol = dsolve(Eq(diff(u(T),T), v(T)), Eq(diff(v(T),T), p*u(T)+q*v(T))) sol1 = exp(Integral(r['c'], t))*sol[1].rhs.subs(T, Integral(r['d'],t)) sol2 = exp(Integral(r['c'], t))*sol[0].rhs.subs(T, Integral(r['d'],t)) return [Eq(x(t), sol1), Eq(y(t), sol2)] def _linear_2eq_order1_type6(x, y, t, r, eq): r""" The equations of this type of ode are . .. math:: x' = f(t) x + g(t) y .. math:: y' = a [f(t) + a h(t)] x + a [g(t) - h(t)] y This is solved by first multiplying the first equation by `-a` and adding it to the second equation to obtain .. math:: y' - a x' = -a h(t) (y - a x) Setting `U = y - ax` and integrating the equation we arrive at .. math:: y - ax = C_1 e^{-a \int h(t) \,dt} and on substituting the value of y in first equation give rise to first order ODEs. After solving for `x`, we can obtain `y` by substituting the value of `x` in second equation. """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) p = 0 q = 0 p1 = cancel(r['c']/cancel(r['c']/r['d']).as_numer_denom()[0]) p2 = cancel(r['a']/cancel(r['a']/r['b']).as_numer_denom()[0]) for n, i in enumerate([p1, p2]): for j in Mul.make_args(collect_const(i)): if not j.has(t): q = j if q!=0 and n==0: if ((r['c']/j - r['a'])/(r['b'] - r['d']/j)) == j: p = 1 s = j break if q!=0 and n==1: if ((r['a']/j - r['c'])/(r['d'] - r['b']/j)) == j: p = 2 s = j break if p == 1: equ = diff(x(t),t) - r['a']*x(t) - r['b']*(s*x(t) + C1*exp(-s*Integral(r['b'] - r['d']/s, t))) hint1 = classify_ode(equ)[1] sol1 = dsolve(equ, hint=hint1+'_Integral').rhs sol2 = s*sol1 + C1*exp(-s*Integral(r['b'] - r['d']/s, t)) elif p ==2: equ = diff(y(t),t) - r['c']*y(t) - r['d']*s*y(t) + C1*exp(-s*Integral(r['d'] - r['b']/s, t)) hint1 = classify_ode(equ)[1] sol2 = dsolve(equ, hint=hint1+'_Integral').rhs sol1 = s*sol2 + C1*exp(-s*Integral(r['d'] - r['b']/s, t)) return [Eq(x(t), sol1), Eq(y(t), sol2)] def _linear_2eq_order1_type7(x, y, t, r, eq): r""" The equations of this type of ode are . .. math:: x' = f(t) x + g(t) y .. math:: y' = h(t) x + p(t) y Differentiating the first equation and substituting the value of `y` from second equation will give a second-order linear equation .. math:: g x'' - (fg + gp + g') x' + (fgp - g^{2} h + f g' - f' g) x = 0 This above equation can be easily integrated if following conditions are satisfied. 1. `fgp - g^{2} h + f g' - f' g = 0` 2. `fgp - g^{2} h + f g' - f' g = ag, fg + gp + g' = bg` If first condition is satisfied then it is solved by current dsolve solver and in second case it becomes a constant coefficient differential equation which is also solved by current solver. Otherwise if the above condition fails then, a particular solution is assumed as `x = x_0(t)` and `y = y_0(t)` Then the general solution is expressed as .. math:: x = C_1 x_0(t) + C_2 x_0(t) \int \frac{g(t) F(t) P(t)}{x_0^{2}(t)} \,dt .. math:: y = C_1 y_0(t) + C_2 [\frac{F(t) P(t)}{x_0(t)} + y_0(t) \int \frac{g(t) F(t) P(t)}{x_0^{2}(t)} \,dt] where C1 and C2 are arbitrary constants and .. math:: F(t) = e^{\int f(t) \,dt} , P(t) = e^{\int p(t) \,dt} """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) e1 = r['a']*r['b']*r['c'] - r['b']**2*r['c'] + r['a']*diff(r['b'],t) - diff(r['a'],t)*r['b'] e2 = r['a']*r['c']*r['d'] - r['b']*r['c']**2 + diff(r['c'],t)*r['d'] - r['c']*diff(r['d'],t) m1 = r['a']*r['b'] + r['b']*r['d'] + diff(r['b'],t) m2 = r['a']*r['c'] + r['c']*r['d'] + diff(r['c'],t) if e1 == 0: sol1 = dsolve(r['b']*diff(x(t),t,t) - m1*diff(x(t),t)).rhs sol2 = dsolve(diff(y(t),t) - r['c']*sol1 - r['d']*y(t)).rhs elif e2 == 0: sol2 = dsolve(r['c']*diff(y(t),t,t) - m2*diff(y(t),t)).rhs sol1 = dsolve(diff(x(t),t) - r['a']*x(t) - r['b']*sol2).rhs elif not (e1/r['b']).has(t) and not (m1/r['b']).has(t): sol1 = dsolve(diff(x(t),t,t) - (m1/r['b'])*diff(x(t),t) - (e1/r['b'])*x(t)).rhs sol2 = dsolve(diff(y(t),t) - r['c']*sol1 - r['d']*y(t)).rhs elif not (e2/r['c']).has(t) and not (m2/r['c']).has(t): sol2 = dsolve(diff(y(t),t,t) - (m2/r['c'])*diff(y(t),t) - (e2/r['c'])*y(t)).rhs sol1 = dsolve(diff(x(t),t) - r['a']*x(t) - r['b']*sol2).rhs else: x0 = Function('x0')(t) # x0 and y0 being particular solutions y0 = Function('y0')(t) F = exp(Integral(r['a'],t)) P = exp(Integral(r['d'],t)) sol1 = C1*x0 + C2*x0*Integral(r['b']*F*P/x0**2, t) sol2 = C1*y0 + C2*(F*P/x0 + y0*Integral(r['b']*F*P/x0**2, t)) return [Eq(x(t), sol1), Eq(y(t), sol2)] def sysode_linear_2eq_order2(match_): x = match_['func'][0].func y = match_['func'][1].func func = match_['func'] fc = match_['func_coeff'] eq = match_['eq'] C1, C2, C3, C4 = get_numbered_constants(eq, num=4) r = dict() t = list(list(eq[0].atoms(Derivative))[0].atoms(Symbol))[0] for i in range(2): eqs = [] for terms in Add.make_args(eq[i]): eqs.append(terms/fc[i,func[i],2]) eq[i] = Add(*eqs) # for equations Eq(diff(x(t),t,t), a1*diff(x(t),t)+b1*diff(y(t),t)+c1*x(t)+d1*y(t)+e1) # and Eq(a2*diff(y(t),t,t), a2*diff(x(t),t)+b2*diff(y(t),t)+c2*x(t)+d2*y(t)+e2) r['a1'] = -fc[0,x(t),1]/fc[0,x(t),2] ; r['a2'] = -fc[1,x(t),1]/fc[1,y(t),2] r['b1'] = -fc[0,y(t),1]/fc[0,x(t),2] ; r['b2'] = -fc[1,y(t),1]/fc[1,y(t),2] r['c1'] = -fc[0,x(t),0]/fc[0,x(t),2] ; r['c2'] = -fc[1,x(t),0]/fc[1,y(t),2] r['d1'] = -fc[0,y(t),0]/fc[0,x(t),2] ; r['d2'] = -fc[1,y(t),0]/fc[1,y(t),2] const = [S(0), S(0)] for i in range(2): for j in Add.make_args(eq[i]): if not (j.has(x(t)) or j.has(y(t))): const[i] += j r['e1'] = -const[0] r['e2'] = -const[1] if match_['type_of_equation'] == 'type1': sol = _linear_2eq_order2_type1(x, y, t, r, eq) elif match_['type_of_equation'] == 'type2': gsol = _linear_2eq_order2_type1(x, y, t, r, eq) psol = _linear_2eq_order2_type2(x, y, t, r, eq) sol = [Eq(x(t), gsol[0].rhs+psol[0]), Eq(y(t), gsol[1].rhs+psol[1])] elif match_['type_of_equation'] == 'type3': sol = _linear_2eq_order2_type3(x, y, t, r, eq) elif match_['type_of_equation'] == 'type4': sol = _linear_2eq_order2_type4(x, y, t, r, eq) elif match_['type_of_equation'] == 'type5': sol = _linear_2eq_order2_type5(x, y, t, r, eq) elif match_['type_of_equation'] == 'type6': sol = _linear_2eq_order2_type6(x, y, t, r, eq) elif match_['type_of_equation'] == 'type7': sol = _linear_2eq_order2_type7(x, y, t, r, eq) elif match_['type_of_equation'] == 'type8': sol = _linear_2eq_order2_type8(x, y, t, r, eq) elif match_['type_of_equation'] == 'type9': sol = _linear_2eq_order2_type9(x, y, t, r, eq) elif match_['type_of_equation'] == 'type10': sol = _linear_2eq_order2_type10(x, y, t, r, eq) elif match_['type_of_equation'] == 'type11': sol = _linear_2eq_order2_type11(x, y, t, r, eq) return sol def _linear_2eq_order2_type1(x, y, t, r, eq): r""" System of two constant-coefficient second-order linear homogeneous differential equations .. math:: x'' = ax + by .. math:: y'' = cx + dy The characteristic equation for above equations .. math:: \lambda^4 - (a + d) \lambda^2 + ad - bc = 0 whose discriminant is `D = (a - d)^2 + 4bc \neq 0` 1. When `ad - bc \neq 0` 1.1. If `D \neq 0`. The characteristic equation has four distinct roots, `\lambda_1, \lambda_2, \lambda_3, \lambda_4`. The general solution of the system is .. math:: x = C_1 b e^{\lambda_1 t} + C_2 b e^{\lambda_2 t} + C_3 b e^{\lambda_3 t} + C_4 b e^{\lambda_4 t} .. math:: y = C_1 (\lambda_1^{2} - a) e^{\lambda_1 t} + C_2 (\lambda_2^{2} - a) e^{\lambda_2 t} + C_3 (\lambda_3^{2} - a) e^{\lambda_3 t} + C_4 (\lambda_4^{2} - a) e^{\lambda_4 t} where `C_1,..., C_4` are arbitrary constants. 1.2. If `D = 0` and `a \neq d`: .. math:: x = 2 C_1 (bt + \frac{2bk}{a - d}) e^{\frac{kt}{2}} + 2 C_2 (bt + \frac{2bk}{a - d}) e^{\frac{-kt}{2}} + 2b C_3 t e^{\frac{kt}{2}} + 2b C_4 t e^{\frac{-kt}{2}} .. math:: y = C_1 (d - a) t e^{\frac{kt}{2}} + C_2 (d - a) t e^{\frac{-kt}{2}} + C_3 [(d - a) t + 2k] e^{\frac{kt}{2}} + C_4 [(d - a) t - 2k] e^{\frac{-kt}{2}} where `C_1,..., C_4` are arbitrary constants and `k = \sqrt{2 (a + d)}` 1.3. If `D = 0` and `a = d \neq 0` and `b = 0`: .. math:: x = 2 \sqrt{a} C_1 e^{\sqrt{a} t} + 2 \sqrt{a} C_2 e^{-\sqrt{a} t} .. math:: y = c C_1 t e^{\sqrt{a} t} - c C_2 t e^{-\sqrt{a} t} + C_3 e^{\sqrt{a} t} + C_4 e^{-\sqrt{a} t} 1.4. If `D = 0` and `a = d \neq 0` and `c = 0`: .. math:: x = b C_1 t e^{\sqrt{a} t} - b C_2 t e^{-\sqrt{a} t} + C_3 e^{\sqrt{a} t} + C_4 e^{-\sqrt{a} t} .. math:: y = 2 \sqrt{a} C_1 e^{\sqrt{a} t} + 2 \sqrt{a} C_2 e^{-\sqrt{a} t} 2. When `ad - bc = 0` and `a^2 + b^2 > 0`. Then the original system becomes .. math:: x'' = ax + by .. math:: y'' = k (ax + by) 2.1. If `a + bk \neq 0`: .. math:: x = C_1 e^{t \sqrt{a + bk}} + C_2 e^{-t \sqrt{a + bk}} + C_3 bt + C_4 b .. math:: y = C_1 k e^{t \sqrt{a + bk}} + C_2 k e^{-t \sqrt{a + bk}} - C_3 at - C_4 a 2.2. If `a + bk = 0`: .. math:: x = C_1 b t^3 + C_2 b t^2 + C_3 t + C_4 .. math:: y = kx + 6 C_1 t + 2 C_2 """ r['a'] = r['c1'] r['b'] = r['d1'] r['c'] = r['c2'] r['d'] = r['d2'] l = Symbol('l') C1, C2, C3, C4 = get_numbered_constants(eq, num=4) chara_eq = l**4 - (r['a']+r['d'])*l**2 + r['a']*r['d'] - r['b']*r['c'] l1 = rootof(chara_eq, 0) l2 = rootof(chara_eq, 1) l3 = rootof(chara_eq, 2) l4 = rootof(chara_eq, 3) D = (r['a'] - r['d'])**2 + 4*r['b']*r['c'] if (r['a']*r['d'] - r['b']*r['c']) != 0: if D != 0: gsol1 = C1*r['b']*exp(l1*t) + C2*r['b']*exp(l2*t) + C3*r['b']*exp(l3*t) \ + C4*r['b']*exp(l4*t) gsol2 = C1*(l1**2-r['a'])*exp(l1*t) + C2*(l2**2-r['a'])*exp(l2*t) + \ C3*(l3**2-r['a'])*exp(l3*t) + C4*(l4**2-r['a'])*exp(l4*t) else: if r['a'] != r['d']: k = sqrt(2*(r['a']+r['d'])) mid = r['b']*t+2*r['b']*k/(r['a']-r['d']) gsol1 = 2*C1*mid*exp(k*t/2) + 2*C2*mid*exp(-k*t/2) + \ 2*r['b']*C3*t*exp(k*t/2) + 2*r['b']*C4*t*exp(-k*t/2) gsol2 = C1*(r['d']-r['a'])*t*exp(k*t/2) + C2*(r['d']-r['a'])*t*exp(-k*t/2) + \ C3*((r['d']-r['a'])*t+2*k)*exp(k*t/2) + C4*((r['d']-r['a'])*t-2*k)*exp(-k*t/2) elif r['a'] == r['d'] != 0 and r['b'] == 0: sa = sqrt(r['a']) gsol1 = 2*sa*C1*exp(sa*t) + 2*sa*C2*exp(-sa*t) gsol2 = r['c']*C1*t*exp(sa*t)-r['c']*C2*t*exp(-sa*t)+C3*exp(sa*t)+C4*exp(-sa*t) elif r['a'] == r['d'] != 0 and r['c'] == 0: sa = sqrt(r['a']) gsol1 = r['b']*C1*t*exp(sa*t)-r['b']*C2*t*exp(-sa*t)+C3*exp(sa*t)+C4*exp(-sa*t) gsol2 = 2*sa*C1*exp(sa*t) + 2*sa*C2*exp(-sa*t) elif (r['a']*r['d'] - r['b']*r['c']) == 0 and (r['a']**2 + r['b']**2) > 0: k = r['c']/r['a'] if r['a'] + r['b']*k != 0: mid = sqrt(r['a'] + r['b']*k) gsol1 = C1*exp(mid*t) + C2*exp(-mid*t) + C3*r['b']*t + C4*r['b'] gsol2 = C1*k*exp(mid*t) + C2*k*exp(-mid*t) - C3*r['a']*t - C4*r['a'] else: gsol1 = C1*r['b']*t**3 + C2*r['b']*t**2 + C3*t + C4 gsol2 = k*gsol1 + 6*C1*t + 2*C2 return [Eq(x(t), gsol1), Eq(y(t), gsol2)] def _linear_2eq_order2_type2(x, y, t, r, eq): r""" The equations in this type are .. math:: x'' = a_1 x + b_1 y + c_1 .. math:: y'' = a_2 x + b_2 y + c_2 The general solution of this system is given by the sum of its particular solution and the general solution of the homogeneous system. The general solution is given by the linear system of 2 equation of order 2 and type 1 1. If `a_1 b_2 - a_2 b_1 \neq 0`. A particular solution will be `x = x_0` and `y = y_0` where the constants `x_0` and `y_0` are determined by solving the linear algebraic system .. math:: a_1 x_0 + b_1 y_0 + c_1 = 0, a_2 x_0 + b_2 y_0 + c_2 = 0 2. If `a_1 b_2 - a_2 b_1 = 0` and `a_1^2 + b_1^2 > 0`. In this case, the system in question becomes .. math:: x'' = ax + by + c_1, y'' = k (ax + by) + c_2 2.1. If `\sigma = a + bk \neq 0`, the particular solution will be .. math:: x = \frac{1}{2} b \sigma^{-1} (c_1 k - c_2) t^2 - \sigma^{-2} (a c_1 + b c_2) .. math:: y = kx + \frac{1}{2} (c_2 - c_1 k) t^2 2.2. If `\sigma = a + bk = 0`, the particular solution will be .. math:: x = \frac{1}{24} b (c_2 - c_1 k) t^4 + \frac{1}{2} c_1 t^2 .. math:: y = kx + \frac{1}{2} (c_2 - c_1 k) t^2 """ x0, y0 = symbols('x0, y0') if r['c1']*r['d2'] - r['c2']*r['d1'] != 0: sol = solve((r['c1']*x0+r['d1']*y0+r['e1'], r['c2']*x0+r['d2']*y0+r['e2']), x0, y0) psol = [sol[x0], sol[y0]] elif r['c1']*r['d2'] - r['c2']*r['d1'] == 0 and (r['c1']**2 + r['d1']**2) > 0: k = r['c2']/r['c1'] sig = r['c1'] + r['d1']*k if sig != 0: psol1 = r['d1']*sig**-1*(r['e1']*k-r['e2'])*t**2/2 - \ sig**-2*(r['c1']*r['e1']+r['d1']*r['e2']) psol2 = k*psol1 + (r['e2'] - r['e1']*k)*t**2/2 psol = [psol1, psol2] else: psol1 = r['d1']*(r['e2']-r['e1']*k)*t**4/24 + r['e1']*t**2/2 psol2 = k*psol1 + (r['e2']-r['e1']*k)*t**2/2 psol = [psol1, psol2] return psol def _linear_2eq_order2_type3(x, y, t, r, eq): r""" These type of equation is used for describing the horizontal motion of a pendulum taking into account the Earth rotation. The solution is given with `a^2 + 4b > 0`: .. math:: x = C_1 \cos(\alpha t) + C_2 \sin(\alpha t) + C_3 \cos(\beta t) + C_4 \sin(\beta t) .. math:: y = -C_1 \sin(\alpha t) + C_2 \cos(\alpha t) - C_3 \sin(\beta t) + C_4 \cos(\beta t) where `C_1,...,C_4` and .. math:: \alpha = \frac{1}{2} a + \frac{1}{2} \sqrt{a^2 + 4b}, \beta = \frac{1}{2} a - \frac{1}{2} \sqrt{a^2 + 4b} """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) if r['b1']**2 - 4*r['c1'] > 0: r['a'] = r['b1'] ; r['b'] = -r['c1'] alpha = r['a']/2 + sqrt(r['a']**2 + 4*r['b'])/2 beta = r['a']/2 - sqrt(r['a']**2 + 4*r['b'])/2 sol1 = C1*cos(alpha*t) + C2*sin(alpha*t) + C3*cos(beta*t) + C4*sin(beta*t) sol2 = -C1*sin(alpha*t) + C2*cos(alpha*t) - C3*sin(beta*t) + C4*cos(beta*t) return [Eq(x(t), sol1), Eq(y(t), sol2)] def _linear_2eq_order2_type4(x, y, t, r, eq): r""" These equations are found in the theory of oscillations .. math:: x'' + a_1 x' + b_1 y' + c_1 x + d_1 y = k_1 e^{i \omega t} .. math:: y'' + a_2 x' + b_2 y' + c_2 x + d_2 y = k_2 e^{i \omega t} The general solution of this linear nonhomogeneous system of constant-coefficient differential equations is given by the sum of its particular solution and the general solution of the corresponding homogeneous system (with `k_1 = k_2 = 0`) 1. A particular solution is obtained by the method of undetermined coefficients: .. math:: x = A_* e^{i \omega t}, y = B_* e^{i \omega t} On substituting these expressions into the original system of differential equations, one arrive at a linear nonhomogeneous system of algebraic equations for the coefficients `A` and `B`. 2. The general solution of the homogeneous system of differential equations is determined by a linear combination of linearly independent particular solutions determined by the method of undetermined coefficients in the form of exponentials: .. math:: x = A e^{\lambda t}, y = B e^{\lambda t} On substituting these expressions into the original system and collecting the coefficients of the unknown `A` and `B`, one obtains .. math:: (\lambda^{2} + a_1 \lambda + c_1) A + (b_1 \lambda + d_1) B = 0 .. math:: (a_2 \lambda + c_2) A + (\lambda^{2} + b_2 \lambda + d_2) B = 0 The determinant of this system must vanish for nontrivial solutions A, B to exist. This requirement results in the following characteristic equation for `\lambda` .. math:: (\lambda^2 + a_1 \lambda + c_1) (\lambda^2 + b_2 \lambda + d_2) - (b_1 \lambda + d_1) (a_2 \lambda + c_2) = 0 If all roots `k_1,...,k_4` of this equation are distinct, the general solution of the original system of the differential equations has the form .. math:: x = C_1 (b_1 \lambda_1 + d_1) e^{\lambda_1 t} - C_2 (b_1 \lambda_2 + d_1) e^{\lambda_2 t} - C_3 (b_1 \lambda_3 + d_1) e^{\lambda_3 t} - C_4 (b_1 \lambda_4 + d_1) e^{\lambda_4 t} .. math:: y = C_1 (\lambda_1^{2} + a_1 \lambda_1 + c_1) e^{\lambda_1 t} + C_2 (\lambda_2^{2} + a_1 \lambda_2 + c_1) e^{\lambda_2 t} + C_3 (\lambda_3^{2} + a_1 \lambda_3 + c_1) e^{\lambda_3 t} + C_4 (\lambda_4^{2} + a_1 \lambda_4 + c_1) e^{\lambda_4 t} """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) k = Symbol('k') Ra, Ca, Rb, Cb = symbols('Ra, Ca, Rb, Cb') a1 = r['a1'] ; a2 = r['a2'] b1 = r['b1'] ; b2 = r['b2'] c1 = r['c1'] ; c2 = r['c2'] d1 = r['d1'] ; d2 = r['d2'] k1 = r['e1'].expand().as_independent(t)[0] k2 = r['e2'].expand().as_independent(t)[0] ew1 = r['e1'].expand().as_independent(t)[1] ew2 = powdenest(ew1).as_base_exp()[1] ew3 = collect(ew2, t).coeff(t) w = cancel(ew3/I) # The particular solution is assumed to be (Ra+I*Ca)*exp(I*w*t) and # (Rb+I*Cb)*exp(I*w*t) for x(t) and y(t) respectively peq1 = (-w**2+c1)*Ra - a1*w*Ca + d1*Rb - b1*w*Cb - k1 peq2 = a1*w*Ra + (-w**2+c1)*Ca + b1*w*Rb + d1*Cb peq3 = c2*Ra - a2*w*Ca + (-w**2+d2)*Rb - b2*w*Cb - k2 peq4 = a2*w*Ra + c2*Ca + b2*w*Rb + (-w**2+d2)*Cb # FIXME: solve for what in what? Ra, Rb, etc I guess # but then psol not used for anything? psol = solve([peq1, peq2, peq3, peq4]) chareq = (k**2+a1*k+c1)*(k**2+b2*k+d2) - (b1*k+d1)*(a2*k+c2) [k1, k2, k3, k4] = roots_quartic(Poly(chareq)) sol1 = -C1*(b1*k1+d1)*exp(k1*t) - C2*(b1*k2+d1)*exp(k2*t) - \ C3*(b1*k3+d1)*exp(k3*t) - C4*(b1*k4+d1)*exp(k4*t) + (Ra+I*Ca)*exp(I*w*t) a1_ = (a1-1) sol2 = C1*(k1**2+a1_*k1+c1)*exp(k1*t) + C2*(k2**2+a1_*k2+c1)*exp(k2*t) + \ C3*(k3**2+a1_*k3+c1)*exp(k3*t) + C4*(k4**2+a1_*k4+c1)*exp(k4*t) + (Rb+I*Cb)*exp(I*w*t) return [Eq(x(t), sol1), Eq(y(t), sol2)] def _linear_2eq_order2_type5(x, y, t, r, eq): r""" The equation which come under this category are .. math:: x'' = a (t y' - y) .. math:: y'' = b (t x' - x) The transformation .. math:: u = t x' - x, b = t y' - y leads to the first-order system .. math:: u' = atv, v' = btu The general solution of this system is given by If `ab > 0`: .. math:: u = C_1 a e^{\frac{1}{2} \sqrt{ab} t^2} + C_2 a e^{-\frac{1}{2} \sqrt{ab} t^2} .. math:: v = C_1 \sqrt{ab} e^{\frac{1}{2} \sqrt{ab} t^2} - C_2 \sqrt{ab} e^{-\frac{1}{2} \sqrt{ab} t^2} If `ab < 0`: .. math:: u = C_1 a \cos(\frac{1}{2} \sqrt{\left|ab\right|} t^2) + C_2 a \sin(-\frac{1}{2} \sqrt{\left|ab\right|} t^2) .. math:: v = C_1 \sqrt{\left|ab\right|} \sin(\frac{1}{2} \sqrt{\left|ab\right|} t^2) + C_2 \sqrt{\left|ab\right|} \cos(-\frac{1}{2} \sqrt{\left|ab\right|} t^2) where `C_1` and `C_2` are arbitrary constants. On substituting the value of `u` and `v` in above equations and integrating the resulting expressions, the general solution will become .. math:: x = C_3 t + t \int \frac{u}{t^2} \,dt, y = C_4 t + t \int \frac{u}{t^2} \,dt where `C_3` and `C_4` are arbitrary constants. """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) r['a'] = -r['d1'] ; r['b'] = -r['c2'] mul = sqrt(abs(r['a']*r['b'])) if r['a']*r['b'] > 0: u = C1*r['a']*exp(mul*t**2/2) + C2*r['a']*exp(-mul*t**2/2) v = C1*mul*exp(mul*t**2/2) - C2*mul*exp(-mul*t**2/2) else: u = C1*r['a']*cos(mul*t**2/2) + C2*r['a']*sin(mul*t**2/2) v = -C1*mul*sin(mul*t**2/2) + C2*mul*cos(mul*t**2/2) sol1 = C3*t + t*Integral(u/t**2, t) sol2 = C4*t + t*Integral(v/t**2, t) return [Eq(x(t), sol1), Eq(y(t), sol2)] def _linear_2eq_order2_type6(x, y, t, r, eq): r""" The equations are .. math:: x'' = f(t) (a_1 x + b_1 y) .. math:: y'' = f(t) (a_2 x + b_2 y) If `k_1` and `k_2` are roots of the quadratic equation .. math:: k^2 - (a_1 + b_2) k + a_1 b_2 - a_2 b_1 = 0 Then by multiplying appropriate constants and adding together original equations we obtain two independent equations: .. math:: z_1'' = k_1 f(t) z_1, z_1 = a_2 x + (k_1 - a_1) y .. math:: z_2'' = k_2 f(t) z_2, z_2 = a_2 x + (k_2 - a_1) y Solving the equations will give the values of `x` and `y` after obtaining the value of `z_1` and `z_2` by solving the differential equation and substituting the result. """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) k = Symbol('k') z = Function('z') num, den = cancel( (r['c1']*x(t) + r['d1']*y(t))/ (r['c2']*x(t) + r['d2']*y(t))).as_numer_denom() f = r['c1']/num.coeff(x(t)) a1 = num.coeff(x(t)) b1 = num.coeff(y(t)) a2 = den.coeff(x(t)) b2 = den.coeff(y(t)) chareq = k**2 - (a1 + b2)*k + a1*b2 - a2*b1 k1, k2 = [rootof(chareq, k) for k in range(Poly(chareq).degree())] z1 = dsolve(diff(z(t),t,t) - k1*f*z(t)).rhs z2 = dsolve(diff(z(t),t,t) - k2*f*z(t)).rhs sol1 = (k1*z2 - k2*z1 + a1*(z1 - z2))/(a2*(k1-k2)) sol2 = (z1 - z2)/(k1 - k2) return [Eq(x(t), sol1), Eq(y(t), sol2)] def _linear_2eq_order2_type7(x, y, t, r, eq): r""" The equations are given as .. math:: x'' = f(t) (a_1 x' + b_1 y') .. math:: y'' = f(t) (a_2 x' + b_2 y') If `k_1` and 'k_2` are roots of the quadratic equation .. math:: k^2 - (a_1 + b_2) k + a_1 b_2 - a_2 b_1 = 0 Then the system can be reduced by adding together the two equations multiplied by appropriate constants give following two independent equations: .. math:: z_1'' = k_1 f(t) z_1', z_1 = a_2 x + (k_1 - a_1) y .. math:: z_2'' = k_2 f(t) z_2', z_2 = a_2 x + (k_2 - a_1) y Integrating these and returning to the original variables, one arrives at a linear algebraic system for the unknowns `x` and `y`: .. math:: a_2 x + (k_1 - a_1) y = C_1 \int e^{k_1 F(t)} \,dt + C_2 .. math:: a_2 x + (k_2 - a_1) y = C_3 \int e^{k_2 F(t)} \,dt + C_4 where `C_1,...,C_4` are arbitrary constants and `F(t) = \int f(t) \,dt` """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) k = Symbol('k') num, den = cancel( (r['a1']*x(t) + r['b1']*y(t))/ (r['a2']*x(t) + r['b2']*y(t))).as_numer_denom() f = r['a1']/num.coeff(x(t)) a1 = num.coeff(x(t)) b1 = num.coeff(y(t)) a2 = den.coeff(x(t)) b2 = den.coeff(y(t)) chareq = k**2 - (a1 + b2)*k + a1*b2 - a2*b1 [k1, k2] = [rootof(chareq, k) for k in range(Poly(chareq).degree())] F = Integral(f, t) z1 = C1*Integral(exp(k1*F), t) + C2 z2 = C3*Integral(exp(k2*F), t) + C4 sol1 = (k1*z2 - k2*z1 + a1*(z1 - z2))/(a2*(k1-k2)) sol2 = (z1 - z2)/(k1 - k2) return [Eq(x(t), sol1), Eq(y(t), sol2)] def _linear_2eq_order2_type8(x, y, t, r, eq): r""" The equation of this category are .. math:: x'' = a f(t) (t y' - y) .. math:: y'' = b f(t) (t x' - x) The transformation .. math:: u = t x' - x, v = t y' - y leads to the system of first-order equations .. math:: u' = a t f(t) v, v' = b t f(t) u The general solution of this system has the form If `ab > 0`: .. math:: u = C_1 a e^{\sqrt{ab} \int t f(t) \,dt} + C_2 a e^{-\sqrt{ab} \int t f(t) \,dt} .. math:: v = C_1 \sqrt{ab} e^{\sqrt{ab} \int t f(t) \,dt} - C_2 \sqrt{ab} e^{-\sqrt{ab} \int t f(t) \,dt} If `ab < 0`: .. math:: u = C_1 a \cos(\sqrt{\left|ab\right|} \int t f(t) \,dt) + C_2 a \sin(-\sqrt{\left|ab\right|} \int t f(t) \,dt) .. math:: v = C_1 \sqrt{\left|ab\right|} \sin(\sqrt{\left|ab\right|} \int t f(t) \,dt) + C_2 \sqrt{\left|ab\right|} \cos(-\sqrt{\left|ab\right|} \int t f(t) \,dt) where `C_1` and `C_2` are arbitrary constants. On substituting the value of `u` and `v` in above equations and integrating the resulting expressions, the general solution will become .. math:: x = C_3 t + t \int \frac{u}{t^2} \,dt, y = C_4 t + t \int \frac{u}{t^2} \,dt where `C_3` and `C_4` are arbitrary constants. """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) num, den = cancel(r['d1']/r['c2']).as_numer_denom() f = -r['d1']/num a = num b = den mul = sqrt(abs(a*b)) Igral = Integral(t*f, t) if a*b > 0: u = C1*a*exp(mul*Igral) + C2*a*exp(-mul*Igral) v = C1*mul*exp(mul*Igral) - C2*mul*exp(-mul*Igral) else: u = C1*a*cos(mul*Igral) + C2*a*sin(mul*Igral) v = -C1*mul*sin(mul*Igral) + C2*mul*cos(mul*Igral) sol1 = C3*t + t*Integral(u/t**2, t) sol2 = C4*t + t*Integral(v/t**2, t) return [Eq(x(t), sol1), Eq(y(t), sol2)] def _linear_2eq_order2_type9(x, y, t, r, eq): r""" .. math:: t^2 x'' + a_1 t x' + b_1 t y' + c_1 x + d_1 y = 0 .. math:: t^2 y'' + a_2 t x' + b_2 t y' + c_2 x + d_2 y = 0 These system of equations are euler type. The substitution of `t = \sigma e^{\tau} (\sigma \neq 0)` leads to the system of constant coefficient linear differential equations .. math:: x'' + (a_1 - 1) x' + b_1 y' + c_1 x + d_1 y = 0 .. math:: y'' + a_2 x' + (b_2 - 1) y' + c_2 x + d_2 y = 0 The general solution of the homogeneous system of differential equations is determined by a linear combination of linearly independent particular solutions determined by the method of undetermined coefficients in the form of exponentials .. math:: x = A e^{\lambda t}, y = B e^{\lambda t} On substituting these expressions into the original system and collecting the coefficients of the unknown `A` and `B`, one obtains .. math:: (\lambda^{2} + (a_1 - 1) \lambda + c_1) A + (b_1 \lambda + d_1) B = 0 .. math:: (a_2 \lambda + c_2) A + (\lambda^{2} + (b_2 - 1) \lambda + d_2) B = 0 The determinant of this system must vanish for nontrivial solutions A, B to exist. This requirement results in the following characteristic equation for `\lambda` .. math:: (\lambda^2 + (a_1 - 1) \lambda + c_1) (\lambda^2 + (b_2 - 1) \lambda + d_2) - (b_1 \lambda + d_1) (a_2 \lambda + c_2) = 0 If all roots `k_1,...,k_4` of this equation are distinct, the general solution of the original system of the differential equations has the form .. math:: x = C_1 (b_1 \lambda_1 + d_1) e^{\lambda_1 t} - C_2 (b_1 \lambda_2 + d_1) e^{\lambda_2 t} - C_3 (b_1 \lambda_3 + d_1) e^{\lambda_3 t} - C_4 (b_1 \lambda_4 + d_1) e^{\lambda_4 t} .. math:: y = C_1 (\lambda_1^{2} + (a_1 - 1) \lambda_1 + c_1) e^{\lambda_1 t} + C_2 (\lambda_2^{2} + (a_1 - 1) \lambda_2 + c_1) e^{\lambda_2 t} + C_3 (\lambda_3^{2} + (a_1 - 1) \lambda_3 + c_1) e^{\lambda_3 t} + C_4 (\lambda_4^{2} + (a_1 - 1) \lambda_4 + c_1) e^{\lambda_4 t} """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) k = Symbol('k') a1 = -r['a1']*t; a2 = -r['a2']*t b1 = -r['b1']*t; b2 = -r['b2']*t c1 = -r['c1']*t**2; c2 = -r['c2']*t**2 d1 = -r['d1']*t**2; d2 = -r['d2']*t**2 eq = (k**2+(a1-1)*k+c1)*(k**2+(b2-1)*k+d2)-(b1*k+d1)*(a2*k+c2) [k1, k2, k3, k4] = roots_quartic(Poly(eq)) sol1 = -C1*(b1*k1+d1)*exp(k1*log(t)) - C2*(b1*k2+d1)*exp(k2*log(t)) - \ C3*(b1*k3+d1)*exp(k3*log(t)) - C4*(b1*k4+d1)*exp(k4*log(t)) a1_ = (a1-1) sol2 = C1*(k1**2+a1_*k1+c1)*exp(k1*log(t)) + C2*(k2**2+a1_*k2+c1)*exp(k2*log(t)) \ + C3*(k3**2+a1_*k3+c1)*exp(k3*log(t)) + C4*(k4**2+a1_*k4+c1)*exp(k4*log(t)) return [Eq(x(t), sol1), Eq(y(t), sol2)] def _linear_2eq_order2_type10(x, y, t, r, eq): r""" The equation of this category are .. math:: (\alpha t^2 + \beta t + \gamma)^{2} x'' = ax + by .. math:: (\alpha t^2 + \beta t + \gamma)^{2} y'' = cx + dy The transformation .. math:: \tau = \int \frac{1}{\alpha t^2 + \beta t + \gamma} \,dt , u = \frac{x}{\sqrt{\left|\alpha t^2 + \beta t + \gamma\right|}} , v = \frac{y}{\sqrt{\left|\alpha t^2 + \beta t + \gamma\right|}} leads to a constant coefficient linear system of equations .. math:: u'' = (a - \alpha \gamma + \frac{1}{4} \beta^{2}) u + b v .. math:: v'' = c u + (d - \alpha \gamma + \frac{1}{4} \beta^{2}) v These system of equations obtained can be solved by type1 of System of two constant-coefficient second-order linear homogeneous differential equations. """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) u, v = symbols('u, v', cls=Function) assert False T = Symbol('T') p = Wild('p', exclude=[t, t**2]) q = Wild('q', exclude=[t, t**2]) s = Wild('s', exclude=[t, t**2]) n = Wild('n', exclude=[t, t**2]) num, den = r['c1'].as_numer_denom() dic = den.match((n*(p*t**2+q*t+s)**2).expand()) eqz = dic[p]*t**2 + dic[q]*t + dic[s] a = num/dic[n] b = cancel(r['d1']*eqz**2) c = cancel(r['c2']*eqz**2) d = cancel(r['d2']*eqz**2) [msol1, msol2] = dsolve([Eq(diff(u(t), t, t), (a - dic[p]*dic[s] + dic[q]**2/4)*u(t) \ + b*v(t)), Eq(diff(v(t),t,t), c*u(t) + (d - dic[p]*dic[s] + dic[q]**2/4)*v(t))]) sol1 = (msol1.rhs*sqrt(abs(eqz))).subs(t, Integral(1/eqz, t)) sol2 = (msol2.rhs*sqrt(abs(eqz))).subs(t, Integral(1/eqz, t)) return [Eq(x(t), sol1), Eq(y(t), sol2)] def _linear_2eq_order2_type11(x, y, t, r, eq): r""" The equations which comes under this type are .. math:: x'' = f(t) (t x' - x) + g(t) (t y' - y) .. math:: y'' = h(t) (t x' - x) + p(t) (t y' - y) The transformation .. math:: u = t x' - x, v = t y' - y leads to the linear system of first-order equations .. math:: u' = t f(t) u + t g(t) v, v' = t h(t) u + t p(t) v On substituting the value of `u` and `v` in transformed equation gives value of `x` and `y` as .. math:: x = C_3 t + t \int \frac{u}{t^2} \,dt , y = C_4 t + t \int \frac{v}{t^2} \,dt. where `C_3` and `C_4` are arbitrary constants. """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) u, v = symbols('u, v', cls=Function) f = -r['c1'] ; g = -r['d1'] h = -r['c2'] ; p = -r['d2'] [msol1, msol2] = dsolve([Eq(diff(u(t),t), t*f*u(t) + t*g*v(t)), Eq(diff(v(t),t), t*h*u(t) + t*p*v(t))]) sol1 = C3*t + t*Integral(msol1.rhs/t**2, t) sol2 = C4*t + t*Integral(msol2.rhs/t**2, t) return [Eq(x(t), sol1), Eq(y(t), sol2)] def sysode_linear_3eq_order1(match_): x = match_['func'][0].func y = match_['func'][1].func z = match_['func'][2].func func = match_['func'] fc = match_['func_coeff'] eq = match_['eq'] C1, C2, C3, C4 = get_numbered_constants(eq, num=4) r = dict() t = list(list(eq[0].atoms(Derivative))[0].atoms(Symbol))[0] for i in range(3): eqs = 0 for terms in Add.make_args(eq[i]): eqs += terms/fc[i,func[i],1] eq[i] = eqs # for equations: # Eq(g1*diff(x(t),t), a1*x(t)+b1*y(t)+c1*z(t)+d1), # Eq(g2*diff(y(t),t), a2*x(t)+b2*y(t)+c2*z(t)+d2), and # Eq(g3*diff(z(t),t), a3*x(t)+b3*y(t)+c3*z(t)+d3) r['a1'] = fc[0,x(t),0]/fc[0,x(t),1]; r['a2'] = fc[1,x(t),0]/fc[1,y(t),1]; r['a3'] = fc[2,x(t),0]/fc[2,z(t),1] r['b1'] = fc[0,y(t),0]/fc[0,x(t),1]; r['b2'] = fc[1,y(t),0]/fc[1,y(t),1]; r['b3'] = fc[2,y(t),0]/fc[2,z(t),1] r['c1'] = fc[0,z(t),0]/fc[0,x(t),1]; r['c2'] = fc[1,z(t),0]/fc[1,y(t),1]; r['c3'] = fc[2,z(t),0]/fc[2,z(t),1] for i in range(3): for j in Add.make_args(eq[i]): if not j.has(x(t), y(t), z(t)): raise NotImplementedError("Only homogeneous problems are supported, non-homogenous are not supported currently.") if match_['type_of_equation'] == 'type1': sol = _linear_3eq_order1_type1(x, y, z, t, r, eq) if match_['type_of_equation'] == 'type2': sol = _linear_3eq_order1_type2(x, y, z, t, r, eq) if match_['type_of_equation'] == 'type3': sol = _linear_3eq_order1_type3(x, y, z, t, r, eq) if match_['type_of_equation'] == 'type4': sol = _linear_3eq_order1_type4(x, y, z, t, r, eq) if match_['type_of_equation'] == 'type6': sol = _linear_neq_order1_type1(match_) return sol def _linear_3eq_order1_type1(x, y, z, t, r, eq): r""" .. math:: x' = ax .. math:: y' = bx + cy .. math:: z' = dx + ky + pz Solution of such equations are forward substitution. Solving first equations gives the value of `x`, substituting it in second and third equation and solving second equation gives `y` and similarly substituting `y` in third equation give `z`. .. math:: x = C_1 e^{at} .. math:: y = \frac{b C_1}{a - c} e^{at} + C_2 e^{ct} .. math:: z = \frac{C_1}{a - p} (d + \frac{bk}{a - c}) e^{at} + \frac{k C_2}{c - p} e^{ct} + C_3 e^{pt} where `C_1, C_2` and `C_3` are arbitrary constants. """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) a = -r['a1']; b = -r['a2']; c = -r['b2'] d = -r['a3']; k = -r['b3']; p = -r['c3'] sol1 = C1*exp(a*t) sol2 = b*C1*exp(a*t)/(a-c) + C2*exp(c*t) sol3 = C1*(d+b*k/(a-c))*exp(a*t)/(a-p) + k*C2*exp(c*t)/(c-p) + C3*exp(p*t) return [Eq(x(t), sol1), Eq(y(t), sol2), Eq(z(t), sol3)] def _linear_3eq_order1_type2(x, y, z, t, r, eq): r""" The equations of this type are .. math:: x' = cy - bz .. math:: y' = az - cx .. math:: z' = bx - ay 1. First integral: .. math:: ax + by + cz = A \qquad - (1) .. math:: x^2 + y^2 + z^2 = B^2 \qquad - (2) where `A` and `B` are arbitrary constants. It follows from these integrals that the integral lines are circles formed by the intersection of the planes `(1)` and sphere `(2)` 2. Solution: .. math:: x = a C_0 + k C_1 \cos(kt) + (c C_2 - b C_3) \sin(kt) .. math:: y = b C_0 + k C_2 \cos(kt) + (a C_2 - c C_3) \sin(kt) .. math:: z = c C_0 + k C_3 \cos(kt) + (b C_2 - a C_3) \sin(kt) where `k = \sqrt{a^2 + b^2 + c^2}` and the four constants of integration, `C_1,...,C_4` are constrained by a single relation, .. math:: a C_1 + b C_2 + c C_3 = 0 """ C0, C1, C2, C3 = get_numbered_constants(eq, num=4, start=0) a = -r['c2']; b = -r['a3']; c = -r['b1'] k = sqrt(a**2 + b**2 + c**2) C3 = (-a*C1 - b*C2)/c sol1 = a*C0 + k*C1*cos(k*t) + (c*C2-b*C3)*sin(k*t) sol2 = b*C0 + k*C2*cos(k*t) + (a*C3-c*C1)*sin(k*t) sol3 = c*C0 + k*C3*cos(k*t) + (b*C1-a*C2)*sin(k*t) return [Eq(x(t), sol1), Eq(y(t), sol2), Eq(z(t), sol3)] def _linear_3eq_order1_type3(x, y, z, t, r, eq): r""" Equations of this system of ODEs .. math:: a x' = bc (y - z) .. math:: b y' = ac (z - x) .. math:: c z' = ab (x - y) 1. First integral: .. math:: a^2 x + b^2 y + c^2 z = A where A is an arbitrary constant. It follows that the integral lines are plane curves. 2. Solution: .. math:: x = C_0 + k C_1 \cos(kt) + a^{-1} bc (C_2 - C_3) \sin(kt) .. math:: y = C_0 + k C_2 \cos(kt) + a b^{-1} c (C_3 - C_1) \sin(kt) .. math:: z = C_0 + k C_3 \cos(kt) + ab c^{-1} (C_1 - C_2) \sin(kt) where `k = \sqrt{a^2 + b^2 + c^2}` and the four constants of integration, `C_1,...,C_4` are constrained by a single relation .. math:: a^2 C_1 + b^2 C_2 + c^2 C_3 = 0 """ C0, C1, C2, C3 = get_numbered_constants(eq, num=4, start=0) c = sqrt(r['b1']*r['c2']) b = sqrt(r['b1']*r['a3']) a = sqrt(r['c2']*r['a3']) C3 = (-a**2*C1-b**2*C2)/c**2 k = sqrt(a**2 + b**2 + c**2) sol1 = C0 + k*C1*cos(k*t) + a**-1*b*c*(C2-C3)*sin(k*t) sol2 = C0 + k*C2*cos(k*t) + a*b**-1*c*(C3-C1)*sin(k*t) sol3 = C0 + k*C3*cos(k*t) + a*b*c**-1*(C1-C2)*sin(k*t) return [Eq(x(t), sol1), Eq(y(t), sol2), Eq(z(t), sol3)] def _linear_3eq_order1_type4(x, y, z, t, r, eq): r""" Equations: .. math:: x' = (a_1 f(t) + g(t)) x + a_2 f(t) y + a_3 f(t) z .. math:: y' = b_1 f(t) x + (b_2 f(t) + g(t)) y + b_3 f(t) z .. math:: z' = c_1 f(t) x + c_2 f(t) y + (c_3 f(t) + g(t)) z The transformation .. math:: x = e^{\int g(t) \,dt} u, y = e^{\int g(t) \,dt} v, z = e^{\int g(t) \,dt} w, \tau = \int f(t) \,dt leads to the system of constant coefficient linear differential equations .. math:: u' = a_1 u + a_2 v + a_3 w .. math:: v' = b_1 u + b_2 v + b_3 w .. math:: w' = c_1 u + c_2 v + c_3 w These system of equations are solved by homogeneous linear system of constant coefficients of `n` equations of first order. Then substituting the value of `u, v` and `w` in transformed equation gives value of `x, y` and `z`. """ u, v, w = symbols('u, v, w', cls=Function) a2, a3 = cancel(r['b1']/r['c1']).as_numer_denom() f = cancel(r['b1']/a2) b1 = cancel(r['a2']/f); b3 = cancel(r['c2']/f) c1 = cancel(r['a3']/f); c2 = cancel(r['b3']/f) a1, g = div(r['a1'],f) b2 = div(r['b2'],f)[0] c3 = div(r['c3'],f)[0] trans_eq = (diff(u(t),t)-a1*u(t)-a2*v(t)-a3*w(t), diff(v(t),t)-b1*u(t)-\ b2*v(t)-b3*w(t), diff(w(t),t)-c1*u(t)-c2*v(t)-c3*w(t)) sol = dsolve(trans_eq) sol1 = exp(Integral(g,t))*((sol[0].rhs).subs(t, Integral(f,t))) sol2 = exp(Integral(g,t))*((sol[1].rhs).subs(t, Integral(f,t))) sol3 = exp(Integral(g,t))*((sol[2].rhs).subs(t, Integral(f,t))) return [Eq(x(t), sol1), Eq(y(t), sol2), Eq(z(t), sol3)] def sysode_linear_neq_order1(match_): sol = _linear_neq_order1_type1(match_) return sol def _linear_neq_order1_type1(match_): r""" System of n first-order constant-coefficient linear nonhomogeneous differential equation .. math:: y'_k = a_{k1} y_1 + a_{k2} y_2 +...+ a_{kn} y_n; k = 1,2,...,n or that can be written as `\vec{y'} = A . \vec{y}` where `\vec{y}` is matrix of `y_k` for `k = 1,2,...n` and `A` is a `n \times n` matrix. Since these equations are equivalent to a first order homogeneous linear differential equation. So the general solution will contain `n` linearly independent parts and solution will consist some type of exponential functions. Assuming `y = \vec{v} e^{rt}` is a solution of the system where `\vec{v}` is a vector of coefficients of `y_1,...,y_n`. Substituting `y` and `y' = r v e^{r t}` into the equation `\vec{y'} = A . \vec{y}`, we get .. math:: r \vec{v} e^{rt} = A \vec{v} e^{rt} .. math:: r \vec{v} = A \vec{v} where `r` comes out to be eigenvalue of `A` and vector `\vec{v}` is the eigenvector of `A` corresponding to `r`. There are three possibilities of eigenvalues of `A` - `n` distinct real eigenvalues - complex conjugate eigenvalues - eigenvalues with multiplicity `k` 1. When all eigenvalues `r_1,..,r_n` are distinct with `n` different eigenvectors `v_1,...v_n` then the solution is given by .. math:: \vec{y} = C_1 e^{r_1 t} \vec{v_1} + C_2 e^{r_2 t} \vec{v_2} +...+ C_n e^{r_n t} \vec{v_n} where `C_1,C_2,...,C_n` are arbitrary constants. 2. When some eigenvalues are complex then in order to make the solution real, we take a linear combination: if `r = a + bi` has an eigenvector `\vec{v} = \vec{w_1} + i \vec{w_2}` then to obtain real-valued solutions to the system, replace the complex-valued solutions `e^{rx} \vec{v}` with real-valued solution `e^{ax} (\vec{w_1} \cos(bx) - \vec{w_2} \sin(bx))` and for `r = a - bi` replace the solution `e^{-r x} \vec{v}` with `e^{ax} (\vec{w_1} \sin(bx) + \vec{w_2} \cos(bx))` 3. If some eigenvalues are repeated. Then we get fewer than `n` linearly independent eigenvectors, we miss some of the solutions and need to construct the missing ones. We do this via generalized eigenvectors, vectors which are not eigenvectors but are close enough that we can use to write down the remaining solutions. For a eigenvalue `r` with eigenvector `\vec{w}` we obtain `\vec{w_2},...,\vec{w_k}` using .. math:: (A - r I) . \vec{w_2} = \vec{w} .. math:: (A - r I) . \vec{w_3} = \vec{w_2} .. math:: \vdots .. math:: (A - r I) . \vec{w_k} = \vec{w_{k-1}} Then the solutions to the system for the eigenspace are `e^{rt} [\vec{w}], e^{rt} [t \vec{w} + \vec{w_2}], e^{rt} [\frac{t^2}{2} \vec{w} + t \vec{w_2} + \vec{w_3}], ...,e^{rt} [\frac{t^{k-1}}{(k-1)!} \vec{w} + \frac{t^{k-2}}{(k-2)!} \vec{w_2} +...+ t \vec{w_{k-1}} + \vec{w_k}]` So, If `\vec{y_1},...,\vec{y_n}` are `n` solution of obtained from three categories of `A`, then general solution to the system `\vec{y'} = A . \vec{y}` .. math:: \vec{y} = C_1 \vec{y_1} + C_2 \vec{y_2} + \cdots + C_n \vec{y_n} """ eq = match_['eq'] func = match_['func'] fc = match_['func_coeff'] n = len(eq) t = list(list(eq[0].atoms(Derivative))[0].atoms(Symbol))[0] constants = numbered_symbols(prefix='C', cls=Symbol, start=1) M = Matrix(n,n,lambda i,j:-fc[i,func[j],0]) evector = M.eigenvects(simplify=True) def is_complex(mat, root): return Matrix(n, 1, lambda i,j: re(mat[i])*cos(im(root)*t) - im(mat[i])*sin(im(root)*t)) def is_complex_conjugate(mat, root): return Matrix(n, 1, lambda i,j: re(mat[i])*sin(abs(im(root))*t) + im(mat[i])*cos(im(root)*t)*abs(im(root))/im(root)) conjugate_root = [] e_vector = zeros(n,1) for evects in evector: if evects[0] not in conjugate_root: # If number of column of an eigenvector is not equal to the multiplicity # of its eigenvalue then the legt eigenvectors are calculated if len(evects[2])!=evects[1]: var_mat = Matrix(n, 1, lambda i,j: Symbol('x'+str(i))) Mnew = (M - evects[0]*eye(evects[2][-1].rows))*var_mat w = [0 for i in range(evects[1])] w[0] = evects[2][-1] for r in range(1, evects[1]): w_ = Mnew - w[r-1] sol_dict = solve(list(w_), var_mat[1:]) sol_dict[var_mat[0]] = var_mat[0] for key, value in sol_dict.items(): sol_dict[key] = value.subs(var_mat[0],1) w[r] = Matrix(n, 1, lambda i,j: sol_dict[var_mat[i]]) evects[2].append(w[r]) for i in range(evects[1]): C = next(constants) for j in range(i+1): if evects[0].has(I): evects[2][j] = simplify(evects[2][j]) e_vector += C*is_complex(evects[2][j], evects[0])*t**(i-j)*exp(re(evects[0])*t)/factorial(i-j) C = next(constants) e_vector += C*is_complex_conjugate(evects[2][j], evects[0])*t**(i-j)*exp(re(evects[0])*t)/factorial(i-j) else: e_vector += C*evects[2][j]*t**(i-j)*exp(evects[0]*t)/factorial(i-j) if evects[0].has(I): conjugate_root.append(conjugate(evects[0])) sol = [] for i in range(len(eq)): sol.append(Eq(func[i],e_vector[i])) return sol def sysode_nonlinear_2eq_order1(match_): func = match_['func'] eq = match_['eq'] fc = match_['func_coeff'] t = list(list(eq[0].atoms(Derivative))[0].atoms(Symbol))[0] if match_['type_of_equation'] == 'type5': sol = _nonlinear_2eq_order1_type5(func, t, eq) return sol x = func[0].func y = func[1].func for i in range(2): eqs = 0 for terms in Add.make_args(eq[i]): eqs += terms/fc[i,func[i],1] eq[i] = eqs if match_['type_of_equation'] == 'type1': sol = _nonlinear_2eq_order1_type1(x, y, t, eq) elif match_['type_of_equation'] == 'type2': sol = _nonlinear_2eq_order1_type2(x, y, t, eq) elif match_['type_of_equation'] == 'type3': sol = _nonlinear_2eq_order1_type3(x, y, t, eq) elif match_['type_of_equation'] == 'type4': sol = _nonlinear_2eq_order1_type4(x, y, t, eq) return sol def _nonlinear_2eq_order1_type1(x, y, t, eq): r""" Equations: .. math:: x' = x^n F(x,y) .. math:: y' = g(y) F(x,y) Solution: .. math:: x = \varphi(y), \int \frac{1}{g(y) F(\varphi(y),y)} \,dy = t + C_2 where if `n \neq 1` .. math:: \varphi = [C_1 + (1-n) \int \frac{1}{g(y)} \,dy]^{\frac{1}{1-n}} if `n = 1` .. math:: \varphi = C_1 e^{\int \frac{1}{g(y)} \,dy} where `C_1` and `C_2` are arbitrary constants. """ C1, C2 = get_numbered_constants(eq, num=2) n = Wild('n', exclude=[x(t),y(t)]) f = Wild('f') u, v = symbols('u, v') r = eq[0].match(diff(x(t),t) - x(t)**n*f) g = ((diff(y(t),t) - eq[1])/r[f]).subs(y(t),v) F = r[f].subs(x(t),u).subs(y(t),v) n = r[n] if n!=1: phi = (C1 + (1-n)*Integral(1/g, v))**(1/(1-n)) else: phi = C1*exp(Integral(1/g, v)) phi = phi.doit() sol2 = solve(Integral(1/(g*F.subs(u,phi)), v).doit() - t - C2, v) sol = [] for sols in sol2: sol.append(Eq(x(t),phi.subs(v, sols))) sol.append(Eq(y(t), sols)) return sol def _nonlinear_2eq_order1_type2(x, y, t, eq): r""" Equations: .. math:: x' = e^{\lambda x} F(x,y) .. math:: y' = g(y) F(x,y) Solution: .. math:: x = \varphi(y), \int \frac{1}{g(y) F(\varphi(y),y)} \,dy = t + C_2 where if `\lambda \neq 0` .. math:: \varphi = -\frac{1}{\lambda} log(C_1 - \lambda \int \frac{1}{g(y)} \,dy) if `\lambda = 0` .. math:: \varphi = C_1 + \int \frac{1}{g(y)} \,dy where `C_1` and `C_2` are arbitrary constants. """ C1, C2 = get_numbered_constants(eq, num=2) n = Wild('n', exclude=[x(t),y(t)]) f = Wild('f') u, v = symbols('u, v') r = eq[0].match(diff(x(t),t) - exp(n*x(t))*f) g = ((diff(y(t),t) - eq[1])/r[f]).subs(y(t),v) F = r[f].subs(x(t),u).subs(y(t),v) n = r[n] if n: phi = -1/n*log(C1 - n*Integral(1/g, v)) else: phi = C1 + Integral(1/g, v) phi = phi.doit() sol2 = solve(Integral(1/(g*F.subs(u,phi)), v).doit() - t - C2, v) sol = [] for sols in sol2: sol.append(Eq(x(t),phi.subs(v, sols))) sol.append(Eq(y(t), sols)) return sol def _nonlinear_2eq_order1_type3(x, y, t, eq): r""" Autonomous system of general form .. math:: x' = F(x,y) .. math:: y' = G(x,y) Assuming `y = y(x, C_1)` where `C_1` is an arbitrary constant is the general solution of the first-order equation .. math:: F(x,y) y'_x = G(x,y) Then the general solution of the original system of equations has the form .. math:: \int \frac{1}{F(x,y(x,C_1))} \,dx = t + C_1 """ C1, C2, C3, C4 = get_numbered_constants(eq, num=4) v = Function('v') u = Symbol('u') f = Wild('f') g = Wild('g') r1 = eq[0].match(diff(x(t),t) - f) r2 = eq[1].match(diff(y(t),t) - g) F = r1[f].subs(x(t), u).subs(y(t), v(u)) G = r2[g].subs(x(t), u).subs(y(t), v(u)) sol2r = dsolve(Eq(diff(v(u), u), G/F)) for sol2s in sol2r: sol1 = solve(Integral(1/F.subs(v(u), sol2s.rhs), u).doit() - t - C2, u) sol = [] for sols in sol1: sol.append(Eq(x(t), sols)) sol.append(Eq(y(t), (sol2s.rhs).subs(u, sols))) return sol def _nonlinear_2eq_order1_type4(x, y, t, eq): r""" Equation: .. math:: x' = f_1(x) g_1(y) \phi(x,y,t) .. math:: y' = f_2(x) g_2(y) \phi(x,y,t) First integral: .. math:: \int \frac{f_2(x)}{f_1(x)} \,dx - \int \frac{g_1(y)}{g_2(y)} \,dy = C where `C` is an arbitrary constant. On solving the first integral for `x` (resp., `y` ) and on substituting the resulting expression into either equation of the original solution, one arrives at a first-order equation for determining `y` (resp., `x` ). """ C1, C2 = get_numbered_constants(eq, num=2) u, v = symbols('u, v') U, V = symbols('U, V', cls=Function) f = Wild('f') g = Wild('g') f1 = Wild('f1', exclude=[v,t]) f2 = Wild('f2', exclude=[v,t]) g1 = Wild('g1', exclude=[u,t]) g2 = Wild('g2', exclude=[u,t]) r1 = eq[0].match(diff(x(t),t) - f) r2 = eq[1].match(diff(y(t),t) - g) num, den = ( (r1[f].subs(x(t),u).subs(y(t),v))/ (r2[g].subs(x(t),u).subs(y(t),v))).as_numer_denom() R1 = num.match(f1*g1) R2 = den.match(f2*g2) phi = (r1[f].subs(x(t),u).subs(y(t),v))/num F1 = R1[f1]; F2 = R2[f2] G1 = R1[g1]; G2 = R2[g2] sol1r = solve(Integral(F2/F1, u).doit() - Integral(G1/G2,v).doit() - C1, u) sol2r = solve(Integral(F2/F1, u).doit() - Integral(G1/G2,v).doit() - C1, v) sol = [] for sols in sol1r: sol.append(Eq(y(t), dsolve(diff(V(t),t) - F2.subs(u,sols).subs(v,V(t))*G2.subs(v,V(t))*phi.subs(u,sols).subs(v,V(t))).rhs)) for sols in sol2r: sol.append(Eq(x(t), dsolve(diff(U(t),t) - F1.subs(u,U(t))*G1.subs(v,sols).subs(u,U(t))*phi.subs(v,sols).subs(u,U(t))).rhs)) return set(sol) def _nonlinear_2eq_order1_type5(func, t, eq): r""" Clairaut system of ODEs .. math:: x = t x' + F(x',y') .. math:: y = t y' + G(x',y') The following are solutions of the system `(i)` straight lines: .. math:: x = C_1 t + F(C_1, C_2), y = C_2 t + G(C_1, C_2) where `C_1` and `C_2` are arbitrary constants; `(ii)` envelopes of the above lines; `(iii)` continuously differentiable lines made up from segments of the lines `(i)` and `(ii)`. """ C1, C2 = get_numbered_constants(eq, num=2) f = Wild('f') g = Wild('g') def check_type(x, y): r1 = eq[0].match(t*diff(x(t),t) - x(t) + f) r2 = eq[1].match(t*diff(y(t),t) - y(t) + g) if not (r1 and r2): r1 = eq[0].match(diff(x(t),t) - x(t)/t + f/t) r2 = eq[1].match(diff(y(t),t) - y(t)/t + g/t) if not (r1 and r2): r1 = (-eq[0]).match(t*diff(x(t),t) - x(t) + f) r2 = (-eq[1]).match(t*diff(y(t),t) - y(t) + g) if not (r1 and r2): r1 = (-eq[0]).match(diff(x(t),t) - x(t)/t + f/t) r2 = (-eq[1]).match(diff(y(t),t) - y(t)/t + g/t) return [r1, r2] for func_ in func: if isinstance(func_, list): x = func[0][0].func y = func[0][1].func [r1, r2] = check_type(x, y) if not (r1 and r2): [r1, r2] = check_type(y, x) x, y = y, x x1 = diff(x(t),t); y1 = diff(y(t),t) return {Eq(x(t), C1*t + r1[f].subs(x1,C1).subs(y1,C2)), Eq(y(t), C2*t + r2[g].subs(x1,C1).subs(y1,C2))} def sysode_nonlinear_3eq_order1(match_): x = match_['func'][0].func y = match_['func'][1].func z = match_['func'][2].func eq = match_['eq'] fc = match_['func_coeff'] func = match_['func'] t = list(list(eq[0].atoms(Derivative))[0].atoms(Symbol))[0] if match_['type_of_equation'] == 'type1': sol = _nonlinear_3eq_order1_type1(x, y, z, t, eq) if match_['type_of_equation'] == 'type2': sol = _nonlinear_3eq_order1_type2(x, y, z, t, eq) if match_['type_of_equation'] == 'type3': sol = _nonlinear_3eq_order1_type3(x, y, z, t, eq) if match_['type_of_equation'] == 'type4': sol = _nonlinear_3eq_order1_type4(x, y, z, t, eq) if match_['type_of_equation'] == 'type5': sol = _nonlinear_3eq_order1_type5(x, y, z, t, eq) return sol def _nonlinear_3eq_order1_type1(x, y, z, t, eq): r""" Equations: .. math:: a x' = (b - c) y z, \enspace b y' = (c - a) z x, \enspace c z' = (a - b) x y First Integrals: .. math:: a x^{2} + b y^{2} + c z^{2} = C_1 .. math:: a^{2} x^{2} + b^{2} y^{2} + c^{2} z^{2} = C_2 where `C_1` and `C_2` are arbitrary constants. On solving the integrals for `y` and `z` and on substituting the resulting expressions into the first equation of the system, we arrives at a separable first-order equation on `x`. Similarly doing that for other two equations, we will arrive at first order equation on `y` and `z` too. References ========== -http://eqworld.ipmnet.ru/en/solutions/sysode/sode0401.pdf """ C1, C2 = get_numbered_constants(eq, num=2) u, v, w = symbols('u, v, w') p = Wild('p', exclude=[x(t), y(t), z(t), t]) q = Wild('q', exclude=[x(t), y(t), z(t), t]) s = Wild('s', exclude=[x(t), y(t), z(t), t]) r = (diff(x(t),t) - eq[0]).match(p*y(t)*z(t)) r.update((diff(y(t),t) - eq[1]).match(q*z(t)*x(t))) r.update((diff(z(t),t) - eq[2]).match(s*x(t)*y(t))) n1, d1 = r[p].as_numer_denom() n2, d2 = r[q].as_numer_denom() n3, d3 = r[s].as_numer_denom() val = solve([n1*u-d1*v+d1*w, d2*u+n2*v-d2*w, d3*u-d3*v-n3*w],[u,v]) vals = [val[v], val[u]] c = lcm(vals[0].as_numer_denom()[1], vals[1].as_numer_denom()[1]) b = vals[0].subs(w,c) a = vals[1].subs(w,c) y_x = sqrt(((c*C1-C2) - a*(c-a)*x(t)**2)/(b*(c-b))) z_x = sqrt(((b*C1-C2) - a*(b-a)*x(t)**2)/(c*(b-c))) z_y = sqrt(((a*C1-C2) - b*(a-b)*y(t)**2)/(c*(a-c))) x_y = sqrt(((c*C1-C2) - b*(c-b)*y(t)**2)/(a*(c-a))) x_z = sqrt(((b*C1-C2) - c*(b-c)*z(t)**2)/(a*(b-a))) y_z = sqrt(((a*C1-C2) - c*(a-c)*z(t)**2)/(b*(a-b))) sol1 = dsolve(a*diff(x(t),t) - (b-c)*y_x*z_x) sol2 = dsolve(b*diff(y(t),t) - (c-a)*z_y*x_y) sol3 = dsolve(c*diff(z(t),t) - (a-b)*x_z*y_z) return [sol1, sol2, sol3] def _nonlinear_3eq_order1_type2(x, y, z, t, eq): r""" Equations: .. math:: a x' = (b - c) y z f(x, y, z, t) .. math:: b y' = (c - a) z x f(x, y, z, t) .. math:: c z' = (a - b) x y f(x, y, z, t) First Integrals: .. math:: a x^{2} + b y^{2} + c z^{2} = C_1 .. math:: a^{2} x^{2} + b^{2} y^{2} + c^{2} z^{2} = C_2 where `C_1` and `C_2` are arbitrary constants. On solving the integrals for `y` and `z` and on substituting the resulting expressions into the first equation of the system, we arrives at a first-order differential equations on `x`. Similarly doing that for other two equations we will arrive at first order equation on `y` and `z`. References ========== -http://eqworld.ipmnet.ru/en/solutions/sysode/sode0402.pdf """ C1, C2 = get_numbered_constants(eq, num=2) u, v, w = symbols('u, v, w') p = Wild('p', exclude=[x(t), y(t), z(t), t]) q = Wild('q', exclude=[x(t), y(t), z(t), t]) s = Wild('s', exclude=[x(t), y(t), z(t), t]) f = Wild('f') r1 = (diff(x(t),t) - eq[0]).match(y(t)*z(t)*f) r = collect_const(r1[f]).match(p*f) r.update(((diff(y(t),t) - eq[1])/r[f]).match(q*z(t)*x(t))) r.update(((diff(z(t),t) - eq[2])/r[f]).match(s*x(t)*y(t))) n1, d1 = r[p].as_numer_denom() n2, d2 = r[q].as_numer_denom() n3, d3 = r[s].as_numer_denom() val = solve([n1*u-d1*v+d1*w, d2*u+n2*v-d2*w, -d3*u+d3*v+n3*w],[u,v]) vals = [val[v], val[u]] c = lcm(vals[0].as_numer_denom()[1], vals[1].as_numer_denom()[1]) a = vals[0].subs(w,c) b = vals[1].subs(w,c) y_x = sqrt(((c*C1-C2) - a*(c-a)*x(t)**2)/(b*(c-b))) z_x = sqrt(((b*C1-C2) - a*(b-a)*x(t)**2)/(c*(b-c))) z_y = sqrt(((a*C1-C2) - b*(a-b)*y(t)**2)/(c*(a-c))) x_y = sqrt(((c*C1-C2) - b*(c-b)*y(t)**2)/(a*(c-a))) x_z = sqrt(((b*C1-C2) - c*(b-c)*z(t)**2)/(a*(b-a))) y_z = sqrt(((a*C1-C2) - c*(a-c)*z(t)**2)/(b*(a-b))) sol1 = dsolve(a*diff(x(t),t) - (b-c)*y_x*z_x*r[f]) sol2 = dsolve(b*diff(y(t),t) - (c-a)*z_y*x_y*r[f]) sol3 = dsolve(c*diff(z(t),t) - (a-b)*x_z*y_z*r[f]) return [sol1, sol2, sol3] def _nonlinear_3eq_order1_type3(x, y, z, t, eq): r""" Equations: .. math:: x' = c F_2 - b F_3, \enspace y' = a F_3 - c F_1, \enspace z' = b F_1 - a F_2 where `F_n = F_n(x, y, z, t)`. 1. First Integral: .. math:: a x + b y + c z = C_1, where C is an arbitrary constant. 2. If we assume function `F_n` to be independent of `t`,i.e, `F_n` = `F_n (x, y, z)` Then, on eliminating `t` and `z` from the first two equation of the system, one arrives at the first-order equation .. math:: \frac{dy}{dx} = \frac{a F_3 (x, y, z) - c F_1 (x, y, z)}{c F_2 (x, y, z) - b F_3 (x, y, z)} where `z = \frac{1}{c} (C_1 - a x - b y)` References ========== -http://eqworld.ipmnet.ru/en/solutions/sysode/sode0404.pdf """ C1 = get_numbered_constants(eq, num=1) u, v, w = symbols('u, v, w') p = Wild('p', exclude=[x(t), y(t), z(t), t]) q = Wild('q', exclude=[x(t), y(t), z(t), t]) s = Wild('s', exclude=[x(t), y(t), z(t), t]) F1, F2, F3 = symbols('F1, F2, F3', cls=Wild) r1 = (diff(x(t),t) - eq[0]).match(F2-F3) r = collect_const(r1[F2]).match(s*F2) r.update(collect_const(r1[F3]).match(q*F3)) if eq[1].has(r[F2]) and not eq[1].has(r[F3]): r[F2], r[F3] = r[F3], r[F2] r[s], r[q] = -r[q], -r[s] r.update((diff(y(t),t) - eq[1]).match(p*r[F3] - r[s]*F1)) a = r[p]; b = r[q]; c = r[s] F1 = r[F1].subs(x(t),u).subs(y(t),v).subs(z(t),w) F2 = r[F2].subs(x(t),u).subs(y(t),v).subs(z(t),w) F3 = r[F3].subs(x(t),u).subs(y(t),v).subs(z(t),w) z_xy = (C1-a*u-b*v)/c y_zx = (C1-a*u-c*w)/b x_yz = (C1-b*v-c*w)/a y_x = dsolve(diff(v(u),u) - ((a*F3-c*F1)/(c*F2-b*F3)).subs(w,z_xy).subs(v,v(u))).rhs z_x = dsolve(diff(w(u),u) - ((b*F1-a*F2)/(c*F2-b*F3)).subs(v,y_zx).subs(w,w(u))).rhs z_y = dsolve(diff(w(v),v) - ((b*F1-a*F2)/(a*F3-c*F1)).subs(u,x_yz).subs(w,w(v))).rhs x_y = dsolve(diff(u(v),v) - ((c*F2-b*F3)/(a*F3-c*F1)).subs(w,z_xy).subs(u,u(v))).rhs y_z = dsolve(diff(v(w),w) - ((a*F3-c*F1)/(b*F1-a*F2)).subs(u,x_yz).subs(v,v(w))).rhs x_z = dsolve(diff(u(w),w) - ((c*F2-b*F3)/(b*F1-a*F2)).subs(v,y_zx).subs(u,u(w))).rhs sol1 = dsolve(diff(u(t),t) - (c*F2 - b*F3).subs(v,y_x).subs(w,z_x).subs(u,u(t))).rhs sol2 = dsolve(diff(v(t),t) - (a*F3 - c*F1).subs(u,x_y).subs(w,z_y).subs(v,v(t))).rhs sol3 = dsolve(diff(w(t),t) - (b*F1 - a*F2).subs(u,x_z).subs(v,y_z).subs(w,w(t))).rhs return [sol1, sol2, sol3] def _nonlinear_3eq_order1_type4(x, y, z, t, eq): r""" Equations: .. math:: x' = c z F_2 - b y F_3, \enspace y' = a x F_3 - c z F_1, \enspace z' = b y F_1 - a x F_2 where `F_n = F_n (x, y, z, t)` 1. First integral: .. math:: a x^{2} + b y^{2} + c z^{2} = C_1 where `C` is an arbitrary constant. 2. Assuming the function `F_n` is independent of `t`: `F_n = F_n (x, y, z)`. Then on eliminating `t` and `z` from the first two equations of the system, one arrives at the first-order equation .. math:: \frac{dy}{dx} = \frac{a x F_3 (x, y, z) - c z F_1 (x, y, z)} {c z F_2 (x, y, z) - b y F_3 (x, y, z)} where `z = \pm \sqrt{\frac{1}{c} (C_1 - a x^{2} - b y^{2})}` References ========== -http://eqworld.ipmnet.ru/en/solutions/sysode/sode0405.pdf """ C1 = get_numbered_constants(eq, num=1) u, v, w = symbols('u, v, w') p = Wild('p', exclude=[x(t), y(t), z(t), t]) q = Wild('q', exclude=[x(t), y(t), z(t), t]) s = Wild('s', exclude=[x(t), y(t), z(t), t]) F1, F2, F3 = symbols('F1, F2, F3', cls=Wild) r1 = eq[0].match(diff(x(t),t) - z(t)*F2 + y(t)*F3) r = collect_const(r1[F2]).match(s*F2) r.update(collect_const(r1[F3]).match(q*F3)) if eq[1].has(r[F2]) and not eq[1].has(r[F3]): r[F2], r[F3] = r[F3], r[F2] r[s], r[q] = -r[q], -r[s] r.update((diff(y(t),t) - eq[1]).match(p*x(t)*r[F3] - r[s]*z(t)*F1)) a = r[p]; b = r[q]; c = r[s] F1 = r[F1].subs(x(t),u).subs(y(t),v).subs(z(t),w) F2 = r[F2].subs(x(t),u).subs(y(t),v).subs(z(t),w) F3 = r[F3].subs(x(t),u).subs(y(t),v).subs(z(t),w) x_yz = sqrt((C1 - b*v**2 - c*w**2)/a) y_zx = sqrt((C1 - c*w**2 - a*u**2)/b) z_xy = sqrt((C1 - a*u**2 - b*v**2)/c) y_x = dsolve(diff(v(u),u) - ((a*u*F3-c*w*F1)/(c*w*F2-b*v*F3)).subs(w,z_xy).subs(v,v(u))).rhs z_x = dsolve(diff(w(u),u) - ((b*v*F1-a*u*F2)/(c*w*F2-b*v*F3)).subs(v,y_zx).subs(w,w(u))).rhs z_y = dsolve(diff(w(v),v) - ((b*v*F1-a*u*F2)/(a*u*F3-c*w*F1)).subs(u,x_yz).subs(w,w(v))).rhs x_y = dsolve(diff(u(v),v) - ((c*w*F2-b*v*F3)/(a*u*F3-c*w*F1)).subs(w,z_xy).subs(u,u(v))).rhs y_z = dsolve(diff(v(w),w) - ((a*u*F3-c*w*F1)/(b*v*F1-a*u*F2)).subs(u,x_yz).subs(v,v(w))).rhs x_z = dsolve(diff(u(w),w) - ((c*w*F2-b*v*F3)/(b*v*F1-a*u*F2)).subs(v,y_zx).subs(u,u(w))).rhs sol1 = dsolve(diff(u(t),t) - (c*w*F2 - b*v*F3).subs(v,y_x).subs(w,z_x).subs(u,u(t))).rhs sol2 = dsolve(diff(v(t),t) - (a*u*F3 - c*w*F1).subs(u,x_y).subs(w,z_y).subs(v,v(t))).rhs sol3 = dsolve(diff(w(t),t) - (b*v*F1 - a*u*F2).subs(u,x_z).subs(v,y_z).subs(w,w(t))).rhs return [sol1, sol2, sol3] def _nonlinear_3eq_order1_type5(x, y, t, eq): r""" .. math:: x' = x (c F_2 - b F_3), \enspace y' = y (a F_3 - c F_1), \enspace z' = z (b F_1 - a F_2) where `F_n = F_n (x, y, z, t)` and are arbitrary functions. First Integral: .. math:: \left|x\right|^{a} \left|y\right|^{b} \left|z\right|^{c} = C_1 where `C` is an arbitrary constant. If the function `F_n` is independent of `t`, then, by eliminating `t` and `z` from the first two equations of the system, one arrives at a first-order equation. References ========== -http://eqworld.ipmnet.ru/en/solutions/sysode/sode0406.pdf """ C1 = get_numbered_constants(eq, num=1) u, v, w = symbols('u, v, w') p = Wild('p', exclude=[x(t), y(t), z(t), t]) q = Wild('q', exclude=[x(t), y(t), z(t), t]) s = Wild('s', exclude=[x(t), y(t), z(t), t]) F1, F2, F3 = symbols('F1, F2, F3', cls=Wild) r1 = eq[0].match(diff(x(t),t) - x(t)*(F2 - F3)) r = collect_const(r1[F2]).match(s*F2) r.update(collect_const(r1[F3]).match(q*F3)) if eq[1].has(r[F2]) and not eq[1].has(r[F3]): r[F2], r[F3] = r[F3], r[F2] r[s], r[q] = -r[q], -r[s] r.update((diff(y(t),t) - eq[1]).match(y(t)*(a*r[F3] - r[c]*F1))) a = r[p]; b = r[q]; c = r[s] F1 = r[F1].subs(x(t),u).subs(y(t),v).subs(z(t),w) F2 = r[F2].subs(x(t),u).subs(y(t),v).subs(z(t),w) F3 = r[F3].subs(x(t),u).subs(y(t),v).subs(z(t),w) x_yz = (C1*v**-b*w**-c)**-a y_zx = (C1*w**-c*u**-a)**-b z_xy = (C1*u**-a*v**-b)**-c y_x = dsolve(diff(v(u),u) - ((v*(a*F3-c*F1))/(u*(c*F2-b*F3))).subs(w,z_xy).subs(v,v(u))).rhs z_x = dsolve(diff(w(u),u) - ((w*(b*F1-a*F2))/(u*(c*F2-b*F3))).subs(v,y_zx).subs(w,w(u))).rhs z_y = dsolve(diff(w(v),v) - ((w*(b*F1-a*F2))/(v*(a*F3-c*F1))).subs(u,x_yz).subs(w,w(v))).rhs x_y = dsolve(diff(u(v),v) - ((u*(c*F2-b*F3))/(v*(a*F3-c*F1))).subs(w,z_xy).subs(u,u(v))).rhs y_z = dsolve(diff(v(w),w) - ((v*(a*F3-c*F1))/(w*(b*F1-a*F2))).subs(u,x_yz).subs(v,v(w))).rhs x_z = dsolve(diff(u(w),w) - ((u*(c*F2-b*F3))/(w*(b*F1-a*F2))).subs(v,y_zx).subs(u,u(w))).rhs sol1 = dsolve(diff(u(t),t) - (u*(c*F2-b*F3)).subs(v,y_x).subs(w,z_x).subs(u,u(t))).rhs sol2 = dsolve(diff(v(t),t) - (v*(a*F3-c*F1)).subs(u,x_y).subs(w,z_y).subs(v,v(t))).rhs sol3 = dsolve(diff(w(t),t) - (w*(b*F1-a*F2)).subs(u,x_z).subs(v,y_z).subs(w,w(t))).rhs return [sol1, sol2, sol3]

8819bcbe4607ffb0a3a4249624f9bc218edabf7d94716c5c3280010e391374e4

from sympy import Order, S, log, limit, lcm_list, pi, Abs from sympy.core.basic import Basic from sympy.core import Add, Mul, Pow from sympy.logic.boolalg import And from sympy.core.expr import AtomicExpr, Expr from sympy.core.numbers import _sympifyit, oo from sympy.core.sympify import _sympify from sympy.sets.sets import (Interval, Intersection, FiniteSet, Union, Complement, EmptySet) from sympy.sets.conditionset import ConditionSet from sympy.functions.elementary.miscellaneous import Min, Max from sympy.utilities import filldedent from sympy.simplify.radsimp import denom from sympy.polys.rationaltools import together from sympy.core.compatibility import iterable def continuous_domain(f, symbol, domain): """ Returns the intervals in the given domain for which the function is continuous. This method is limited by the ability to determine the various singularities and discontinuities of the given function. Parameters ========== f : Expr The concerned function. symbol : Symbol The variable for which the intervals are to be determined. domain : Interval The domain over which the continuity of the symbol has to be checked. Examples ======== >>> from sympy import Symbol, S, tan, log, pi, sqrt >>> from sympy.sets import Interval >>> from sympy.calculus.util import continuous_domain >>> x = Symbol('x') >>> continuous_domain(1/x, x, S.Reals) Union(Interval.open(-oo, 0), Interval.open(0, oo)) >>> continuous_domain(tan(x), x, Interval(0, pi)) Union(Interval.Ropen(0, pi/2), Interval.Lopen(pi/2, pi)) >>> continuous_domain(sqrt(x - 2), x, Interval(-5, 5)) Interval(2, 5) >>> continuous_domain(log(2*x - 1), x, S.Reals) Interval.open(1/2, oo) Returns ======= Interval Union of all intervals where the function is continuous. Raises ====== NotImplementedError If the method to determine continuity of such a function has not yet been developed. """ from sympy.solvers.inequalities import solve_univariate_inequality from sympy.solvers.solveset import solveset, _has_rational_power if domain.is_subset(S.Reals): constrained_interval = domain for atom in f.atoms(Pow): predicate, denomin = _has_rational_power(atom, symbol) constraint = S.EmptySet if predicate and denomin == 2: constraint = solve_univariate_inequality(atom.base >= 0, symbol).as_set() constrained_interval = Intersection(constraint, constrained_interval) for atom in f.atoms(log): constraint = solve_univariate_inequality(atom.args[0] > 0, symbol).as_set() constrained_interval = Intersection(constraint, constrained_interval) domain = constrained_interval try: sings = S.EmptySet if f.has(Abs): sings = solveset(1/f, symbol, domain) + \ solveset(denom(together(f)), symbol, domain) else: for atom in f.atoms(Pow): predicate, denomin = _has_rational_power(atom, symbol) if predicate and denomin == 2: sings = solveset(1/f, symbol, domain) +\ solveset(denom(together(f)), symbol, domain) break else: sings = Intersection(solveset(1/f, symbol), domain) + \ solveset(denom(together(f)), symbol, domain) except NotImplementedError: import sys raise (NotImplementedError("Methods for determining the continuous domains" " of this function have not been developed."), None, sys.exc_info()[2]) return domain - sings def function_range(f, symbol, domain): """ Finds the range of a function in a given domain. This method is limited by the ability to determine the singularities and determine limits. Examples ======== >>> from sympy import Symbol, S, exp, log, pi, sqrt, sin, tan >>> from sympy.sets import Interval >>> from sympy.calculus.util import function_range >>> x = Symbol('x') >>> function_range(sin(x), x, Interval(0, 2*pi)) Interval(-1, 1) >>> function_range(tan(x), x, Interval(-pi/2, pi/2)) Interval(-oo, oo) >>> function_range(1/x, x, S.Reals) Union(Interval.open(-oo, 0), Interval.open(0, oo)) >>> function_range(exp(x), x, S.Reals) Interval.open(0, oo) >>> function_range(log(x), x, S.Reals) Interval(-oo, oo) >>> function_range(sqrt(x), x , Interval(-5, 9)) Interval(0, 3) """ from sympy.solvers.solveset import solveset if isinstance(domain, EmptySet): return S.EmptySet period = periodicity(f, symbol) if period is S.Zero: # the expression is constant wrt symbol return FiniteSet(f.expand()) if period is not None: if isinstance(domain, Interval): if (domain.inf - domain.sup).is_infinite: domain = Interval(0, period) elif isinstance(domain, Union): for sub_dom in domain.args: if isinstance(sub_dom, Interval) and \ ((sub_dom.inf - sub_dom.sup).is_infinite): domain = Interval(0, period) intervals = continuous_domain(f, symbol, domain) range_int = S.EmptySet if isinstance(intervals,(Interval, FiniteSet)): interval_iter = (intervals,) elif isinstance(intervals, Union): interval_iter = intervals.args else: raise NotImplementedError(filldedent(''' Unable to find range for the given domain. ''')) for interval in interval_iter: if isinstance(interval, FiniteSet): for singleton in interval: if singleton in domain: range_int += FiniteSet(f.subs(symbol, singleton)) elif isinstance(interval, Interval): vals = S.EmptySet critical_points = S.EmptySet critical_values = S.EmptySet bounds = ((interval.left_open, interval.inf, '+'), (interval.right_open, interval.sup, '-')) for is_open, limit_point, direction in bounds: if is_open: critical_values += FiniteSet(limit(f, symbol, limit_point, direction)) vals += critical_values else: vals += FiniteSet(f.subs(symbol, limit_point)) solution = solveset(f.diff(symbol), symbol, interval) if not iterable(solution): raise NotImplementedError('Unable to find critical points for {}'.format(f)) critical_points += solution for critical_point in critical_points: vals += FiniteSet(f.subs(symbol, critical_point)) left_open, right_open = False, False if critical_values is not S.EmptySet: if critical_values.inf == vals.inf: left_open = True if critical_values.sup == vals.sup: right_open = True range_int += Interval(vals.inf, vals.sup, left_open, right_open) else: raise NotImplementedError(filldedent(''' Unable to find range for the given domain. ''')) return range_int def not_empty_in(finset_intersection, *syms): """ Finds the domain of the functions in `finite_set` in which the `finite_set` is not-empty Parameters ========== finset_intersection: The unevaluated intersection of FiniteSet containing real-valued functions with Union of Sets syms: Tuple of symbols Symbol for which domain is to be found Raises ====== NotImplementedError The algorithms to find the non-emptiness of the given FiniteSet are not yet implemented. ValueError The input is not valid. RuntimeError It is a bug, please report it to the github issue tracker (https://github.com/sympy/sympy/issues). Examples ======== >>> from sympy import FiniteSet, Interval, not_empty_in, oo >>> from sympy.abc import x >>> not_empty_in(FiniteSet(x/2).intersect(Interval(0, 1)), x) Interval(0, 2) >>> not_empty_in(FiniteSet(x, x**2).intersect(Interval(1, 2)), x) Union(Interval(-sqrt(2), -1), Interval(1, 2)) >>> not_empty_in(FiniteSet(x**2/(x + 2)).intersect(Interval(1, oo)), x) Union(Interval.Lopen(-2, -1), Interval(2, oo)) """ # TODO: handle piecewise defined functions # TODO: handle transcendental functions # TODO: handle multivariate functions if len(syms) == 0: raise ValueError("One or more symbols must be given in syms.") if finset_intersection.is_EmptySet: return EmptySet() if isinstance(finset_intersection, Union): elm_in_sets = finset_intersection.args[0] return Union(not_empty_in(finset_intersection.args[1], *syms), elm_in_sets) if isinstance(finset_intersection, FiniteSet): finite_set = finset_intersection _sets = S.Reals else: finite_set = finset_intersection.args[1] _sets = finset_intersection.args[0] if not isinstance(finite_set, FiniteSet): raise ValueError('A FiniteSet must be given, not %s: %s' % (type(finite_set), finite_set)) if len(syms) == 1: symb = syms[0] else: raise NotImplementedError('more than one variables %s not handled' % (syms,)) def elm_domain(expr, intrvl): """ Finds the domain of an expression in any given interval """ from sympy.solvers.solveset import solveset _start = intrvl.start _end = intrvl.end _singularities = solveset(expr.as_numer_denom()[1], symb, domain=S.Reals) if intrvl.right_open: if _end is S.Infinity: _domain1 = S.Reals else: _domain1 = solveset(expr < _end, symb, domain=S.Reals) else: _domain1 = solveset(expr <= _end, symb, domain=S.Reals) if intrvl.left_open: if _start is S.NegativeInfinity: _domain2 = S.Reals else: _domain2 = solveset(expr > _start, symb, domain=S.Reals) else: _domain2 = solveset(expr >= _start, symb, domain=S.Reals) # domain in the interval expr_with_sing = Intersection(_domain1, _domain2) expr_domain = Complement(expr_with_sing, _singularities) return expr_domain if isinstance(_sets, Interval): return Union(*[elm_domain(element, _sets) for element in finite_set]) if isinstance(_sets, Union): _domain = S.EmptySet for intrvl in _sets.args: _domain_element = Union(*[elm_domain(element, intrvl) for element in finite_set]) _domain = Union(_domain, _domain_element) return _domain def periodicity(f, symbol, check=False): """ Tests the given function for periodicity in the given symbol. Parameters ========== f : Expr. The concerned function. symbol : Symbol The variable for which the period is to be determined. check : Boolean The flag to verify whether the value being returned is a period or not. Returns ======= period The period of the function is returned. `None` is returned when the function is aperiodic or has a complex period. The value of `0` is returned as the period of a constant function. Raises ====== NotImplementedError The value of the period computed cannot be verified. Notes ===== Currently, we do not support functions with a complex period. The period of functions having complex periodic values such as `exp`, `sinh` is evaluated to `None`. The value returned might not be the "fundamental" period of the given function i.e. it may not be the smallest periodic value of the function. The verification of the period through the `check` flag is not reliable due to internal simplification of the given expression. Hence, it is set to `False` by default. Examples ======== >>> from sympy import Symbol, sin, cos, tan, exp >>> from sympy.calculus.util import periodicity >>> x = Symbol('x') >>> f = sin(x) + sin(2*x) + sin(3*x) >>> periodicity(f, x) 2*pi >>> periodicity(sin(x)*cos(x), x) pi >>> periodicity(exp(tan(2*x) - 1), x) pi/2 >>> periodicity(sin(4*x)**cos(2*x), x) pi >>> periodicity(exp(x), x) """ from sympy.core.function import diff from sympy.core.mod import Mod from sympy.core.relational import Relational from sympy.functions.elementary.complexes import Abs from sympy.functions.elementary.trigonometric import ( TrigonometricFunction, sin, cos, csc, sec) from sympy.simplify.simplify import simplify from sympy.solvers.decompogen import decompogen from sympy.polys.polytools import degree, lcm_list def _check(orig_f, period): '''Return the checked period or raise an error.''' new_f = orig_f.subs(symbol, symbol + period) if new_f.equals(orig_f): return period else: raise NotImplementedError(filldedent(''' The period of the given function cannot be verified. When `%s` was replaced with `%s + %s` in `%s`, the result was `%s` which was not recognized as being the same as the original function. So either the period was wrong or the two forms were not recognized as being equal. Set check=False to obtain the value.''' % (symbol, symbol, period, orig_f, new_f))) orig_f = f period = None if isinstance(f, Relational): f = f.lhs - f.rhs f = simplify(f) if symbol not in f.free_symbols: return S.Zero if isinstance(f, TrigonometricFunction): try: period = f.period(symbol) except NotImplementedError: pass if isinstance(f, Abs): arg = f.args[0] if isinstance(arg, (sec, csc, cos)): # all but tan and cot might have a # a period that is half as large # so recast as sin arg = sin(arg.args[0]) period = periodicity(arg, symbol) if period is not None and isinstance(arg, sin): # the argument of Abs was a trigonometric other than # cot or tan; test to see if the half-period # is valid. Abs(arg) has behaviour equivalent to # orig_f, so use that for test: orig_f = Abs(arg) try: return _check(orig_f, period/2) except NotImplementedError as err: if check: raise NotImplementedError(err) # else let new orig_f and period be # checked below if f.is_Pow: base, expo = f.args base_has_sym = base.has(symbol) expo_has_sym = expo.has(symbol) if base_has_sym and not expo_has_sym: period = periodicity(base, symbol) elif expo_has_sym and not base_has_sym: period = periodicity(expo, symbol) else: period = _periodicity(f.args, symbol) elif f.is_Mul: coeff, g = f.as_independent(symbol, as_Add=False) if isinstance(g, TrigonometricFunction) or coeff is not S.One: period = periodicity(g, symbol) else: period = _periodicity(g.args, symbol) elif f.is_Add: k, g = f.as_independent(symbol) if k is not S.Zero: return periodicity(g, symbol) period = _periodicity(g.args, symbol) elif isinstance(f, Mod): a, n = f.args if a == symbol: period = n elif isinstance(a, TrigonometricFunction): period = periodicity(a, symbol) #check if 'f' is linear in 'symbol' elif (a.is_polynomial(symbol) and degree(a, symbol) == 1 and symbol not in n.free_symbols): period = Abs(n / a.diff(symbol)) elif period is None: from sympy.solvers.decompogen import compogen g_s = decompogen(f, symbol) num_of_gs = len(g_s) if num_of_gs > 1: for index, g in enumerate(reversed(g_s)): start_index = num_of_gs - 1 - index g = compogen(g_s[start_index:], symbol) if g != orig_f and g != f: # Fix for issue 12620 period = periodicity(g, symbol) if period is not None: break if period is not None: if check: return _check(orig_f, period) return period return None def _periodicity(args, symbol): """Helper for periodicity to find the period of a list of simpler functions. It uses the `lcim` method to find the least common period of all the functions. """ periods = [] for f in args: period = periodicity(f, symbol) if period is None: return None if period is not S.Zero: periods.append(period) if len(periods) > 1: return lcim(periods) return periods[0] def lcim(numbers): """Returns the least common integral multiple of a list of numbers. The numbers can be rational or irrational or a mixture of both. `None` is returned for incommensurable numbers. Examples ======== >>> from sympy import S, pi >>> from sympy.calculus.util import lcim >>> lcim([S(1)/2, S(3)/4, S(5)/6]) 15/2 >>> lcim([2*pi, 3*pi, pi, pi/2]) 6*pi >>> lcim([S(1), 2*pi]) """ result = None if all(num.is_irrational for num in numbers): factorized_nums = list(map(lambda num: num.factor(), numbers)) factors_num = list( map(lambda num: num.as_coeff_Mul(), factorized_nums)) term = factors_num[0][1] if all(factor == term for coeff, factor in factors_num): common_term = term coeffs = [coeff for coeff, factor in factors_num] result = lcm_list(coeffs) * common_term elif all(num.is_rational for num in numbers): result = lcm_list(numbers) else: pass return result class AccumulationBounds(AtomicExpr): r""" # Note AccumulationBounds has an alias: AccumBounds AccumulationBounds represent an interval `[a, b]`, which is always closed at the ends. Here `a` and `b` can be any value from extended real numbers. The intended meaning of AccummulationBounds is to give an approximate location of the accumulation points of a real function at a limit point. Let `a` and `b` be reals such that a <= b. `\left\langle a, b\right\rangle = \{x \in \mathbb{R} \mid a \le x \le b\}` `\left\langle -\infty, b\right\rangle = \{x \in \mathbb{R} \mid x \le b\} \cup \{-\infty, \infty\}` `\left\langle a, \infty \right\rangle = \{x \in \mathbb{R} \mid a \le x\} \cup \{-\infty, \infty\}` `\left\langle -\infty, \infty \right\rangle = \mathbb{R} \cup \{-\infty, \infty\}` `oo` and `-oo` are added to the second and third definition respectively, since if either `-oo` or `oo` is an argument, then the other one should be included (though not as an end point). This is forced, since we have, for example, `1/AccumBounds(0, 1) = AccumBounds(1, oo)`, and the limit at `0` is not one-sided. As x tends to `0-`, then `1/x -> -oo`, so `-oo` should be interpreted as belonging to `AccumBounds(1, oo)` though it need not appear explicitly. In many cases it suffices to know that the limit set is bounded. However, in some other cases more exact information could be useful. For example, all accumulation values of cos(x) + 1 are non-negative. (AccumBounds(-1, 1) + 1 = AccumBounds(0, 2)) A AccumulationBounds object is defined to be real AccumulationBounds, if its end points are finite reals. Let `X`, `Y` be real AccumulationBounds, then their sum, difference, product are defined to be the following sets: `X + Y = \{ x+y \mid x \in X \cap y \in Y\}` `X - Y = \{ x-y \mid x \in X \cap y \in Y\}` `X * Y = \{ x*y \mid x \in X \cap y \in Y\}` There is, however, no consensus on Interval division. `X / Y = \{ z \mid \exists x \in X, y \in Y \mid y \neq 0, z = x/y\}` Note: According to this definition the quotient of two AccumulationBounds may not be a AccumulationBounds object but rather a union of AccumulationBounds. Note ==== The main focus in the interval arithmetic is on the simplest way to calculate upper and lower endpoints for the range of values of a function in one or more variables. These barriers are not necessarily the supremum or infimum, since the precise calculation of those values can be difficult or impossible. Examples ======== >>> from sympy import AccumBounds, sin, exp, log, pi, E, S, oo >>> from sympy.abc import x >>> AccumBounds(0, 1) + AccumBounds(1, 2) AccumBounds(1, 3) >>> AccumBounds(0, 1) - AccumBounds(0, 2) AccumBounds(-2, 1) >>> AccumBounds(-2, 3)*AccumBounds(-1, 1) AccumBounds(-3, 3) >>> AccumBounds(1, 2)*AccumBounds(3, 5) AccumBounds(3, 10) The exponentiation of AccumulationBounds is defined as follows: If 0 does not belong to `X` or `n > 0` then `X^n = \{ x^n \mid x \in X\}` otherwise `X^n = \{ x^n \mid x \neq 0, x \in X\} \cup \{-\infty, \infty\}` Here for fractional `n`, the part of `X` resulting in a complex AccumulationBounds object is neglected. >>> AccumBounds(-1, 4)**(S(1)/2) AccumBounds(0, 2) >>> AccumBounds(1, 2)**2 AccumBounds(1, 4) >>> AccumBounds(-1, oo)**(-1) AccumBounds(-oo, oo) Note: `<a, b>^2` is not same as `<a, b>*<a, b>` >>> AccumBounds(-1, 1)**2 AccumBounds(0, 1) >>> AccumBounds(1, 3) < 4 True >>> AccumBounds(1, 3) < -1 False Some elementary functions can also take AccumulationBounds as input. A function `f` evaluated for some real AccumulationBounds `<a, b>` is defined as `f(\left\langle a, b\right\rangle) = \{ f(x) \mid a \le x \le b \}` >>> sin(AccumBounds(pi/6, pi/3)) AccumBounds(1/2, sqrt(3)/2) >>> exp(AccumBounds(0, 1)) AccumBounds(1, E) >>> log(AccumBounds(1, E)) AccumBounds(0, 1) Some symbol in an expression can be substituted for a AccumulationBounds object. But it doesn't necessarily evaluate the AccumulationBounds for that expression. Same expression can be evaluated to different values depending upon the form it is used for substitution. For example: >>> (x**2 + 2*x + 1).subs(x, AccumBounds(-1, 1)) AccumBounds(-1, 4) >>> ((x + 1)**2).subs(x, AccumBounds(-1, 1)) AccumBounds(0, 4) References ========== .. [1] https://en.wikipedia.org/wiki/Interval_arithmetic .. [2] http://fab.cba.mit.edu/classes/S62.12/docs/Hickey_interval.pdf Notes ===== Do not use ``AccumulationBounds`` for floating point interval arithmetic calculations, use ``mpmath.iv`` instead. """ is_real = True def __new__(cls, min, max): min = _sympify(min) max = _sympify(max) inftys = [S.Infinity, S.NegativeInfinity] # Only allow real intervals (use symbols with 'is_real=True'). if not (min.is_real or min in inftys) \ or not (max.is_real or max in inftys): raise ValueError("Only real AccumulationBounds are supported") # Make sure that the created AccumBounds object will be valid. if max.is_comparable and min.is_comparable: if max < min: raise ValueError( "Lower limit should be smaller than upper limit") if max == min: return max return Basic.__new__(cls, min, max) # setting the operation priority _op_priority = 11.0 @property def min(self): """ Returns the minimum possible value attained by AccumulationBounds object. Examples ======== >>> from sympy import AccumBounds >>> AccumBounds(1, 3).min 1 """ return self.args[0] @property def max(self): """ Returns the maximum possible value attained by AccumulationBounds object. Examples ======== >>> from sympy import AccumBounds >>> AccumBounds(1, 3).max 3 """ return self.args[1] @property def delta(self): """ Returns the difference of maximum possible value attained by AccumulationBounds object and minimum possible value attained by AccumulationBounds object. Examples ======== >>> from sympy import AccumBounds >>> AccumBounds(1, 3).delta 2 """ return self.max - self.min @property def mid(self): """ Returns the mean of maximum possible value attained by AccumulationBounds object and minimum possible value attained by AccumulationBounds object. Examples ======== >>> from sympy import AccumBounds >>> AccumBounds(1, 3).mid 2 """ return (self.min + self.max) / 2 @_sympifyit('other', NotImplemented) def _eval_power(self, other): return self.__pow__(other) @_sympifyit('other', NotImplemented) def __add__(self, other): if isinstance(other, Expr): if isinstance(other, AccumBounds): return AccumBounds( Add(self.min, other.min), Add(self.max, other.max)) if other is S.Infinity and self.min is S.NegativeInfinity or \ other is S.NegativeInfinity and self.max is S.Infinity: return AccumBounds(-oo, oo) elif other.is_real: return AccumBounds(Add(self.min, other), Add(self.max, other)) return Add(self, other, evaluate=False) return NotImplemented __radd__ = __add__ def __neg__(self): return AccumBounds(-self.max, -self.min) @_sympifyit('other', NotImplemented) def __sub__(self, other): if isinstance(other, Expr): if isinstance(other, AccumBounds): return AccumBounds( Add(self.min, -other.max), Add(self.max, -other.min)) if other is S.NegativeInfinity and self.min is S.NegativeInfinity or \ other is S.Infinity and self.max is S.Infinity: return AccumBounds(-oo, oo) elif other.is_real: return AccumBounds( Add(self.min, -other), Add(self.max, -other)) return Add(self, -other, evaluate=False) return NotImplemented @_sympifyit('other', NotImplemented) def __rsub__(self, other): return self.__neg__() + other @_sympifyit('other', NotImplemented) def __mul__(self, other): if isinstance(other, Expr): if isinstance(other, AccumBounds): return AccumBounds(Min(Mul(self.min, other.min), Mul(self.min, other.max), Mul(self.max, other.min), Mul(self.max, other.max)), Max(Mul(self.min, other.min), Mul(self.min, other.max), Mul(self.max, other.min), Mul(self.max, other.max))) if other is S.Infinity: if self.min.is_zero: return AccumBounds(0, oo) if self.max.is_zero: return AccumBounds(-oo, 0) if other is S.NegativeInfinity: if self.min.is_zero: return AccumBounds(-oo, 0) if self.max.is_zero: return AccumBounds(0, oo) if other.is_real: if other.is_zero: if self == AccumBounds(-oo, oo): return AccumBounds(-oo, oo) if self.max is S.Infinity: return AccumBounds(0, oo) if self.min is S.NegativeInfinity: return AccumBounds(-oo, 0) return S.Zero if other.is_positive: return AccumBounds( Mul(self.min, other), Mul(self.max, other)) elif other.is_negative: return AccumBounds( Mul(self.max, other), Mul(self.min, other)) if isinstance(other, Order): return other return Mul(self, other, evaluate=False) return NotImplemented __rmul__ = __mul__ @_sympifyit('other', NotImplemented) def __div__(self, other): if isinstance(other, Expr): if isinstance(other, AccumBounds): if S.Zero not in other: return self * AccumBounds(1/other.max, 1/other.min) if S.Zero in self and S.Zero in other: if self.min.is_zero and other.min.is_zero: return AccumBounds(0, oo) if self.max.is_zero and other.min.is_zero: return AccumBounds(-oo, 0) return AccumBounds(-oo, oo) if self.max.is_negative: if other.min.is_negative: if other.max.is_zero: return AccumBounds(self.max / other.min, oo) if other.max.is_positive: # the actual answer is a Union of AccumBounds, # Union(AccumBounds(-oo, self.max/other.max), # AccumBounds(self.max/other.min, oo)) return AccumBounds(-oo, oo) if other.min.is_zero and other.max.is_positive: return AccumBounds(-oo, self.max / other.max) if self.min.is_positive: if other.min.is_negative: if other.max.is_zero: return AccumBounds(-oo, self.min / other.min) if other.max.is_positive: # the actual answer is a Union of AccumBounds, # Union(AccumBounds(-oo, self.min/other.min), # AccumBounds(self.min/other.max, oo)) return AccumBounds(-oo, oo) if other.min.is_zero and other.max.is_positive: return AccumBounds(self.min / other.max, oo) elif other.is_real: if other is S.Infinity or other is S.NegativeInfinity: if self == AccumBounds(-oo, oo): return AccumBounds(-oo, oo) if self.max is S.Infinity: return AccumBounds(Min(0, other), Max(0, other)) if self.min is S.NegativeInfinity: return AccumBounds(Min(0, -other), Max(0, -other)) if other.is_positive: return AccumBounds(self.min / other, self.max / other) elif other.is_negative: return AccumBounds(self.max / other, self.min / other) return Mul(self, 1 / other, evaluate=False) return NotImplemented __truediv__ = __div__ @_sympifyit('other', NotImplemented) def __rdiv__(self, other): if isinstance(other, Expr): if other.is_real: if other.is_zero: return S.Zero if S.Zero in self: if self.min == S.Zero: if other.is_positive: return AccumBounds(Mul(other, 1 / self.max), oo) if other.is_negative: return AccumBounds(-oo, Mul(other, 1 / self.max)) if self.max == S.Zero: if other.is_positive: return AccumBounds(-oo, Mul(other, 1 / self.min)) if other.is_negative: return AccumBounds(Mul(other, 1 / self.min), oo) return AccumBounds(-oo, oo) else: return AccumBounds(Min(other / self.min, other / self.max), Max(other / self.min, other / self.max)) return Mul(other, 1 / self, evaluate=False) else: return NotImplemented __rtruediv__ = __rdiv__ @_sympifyit('other', NotImplemented) def __pow__(self, other): from sympy.functions.elementary.miscellaneous import real_root if isinstance(other, Expr): if other is S.Infinity: if self.min.is_nonnegative: if self.max < 1: return S.Zero if self.min > 1: return S.Infinity return AccumBounds(0, oo) elif self.max.is_negative: if self.min > -1: return S.Zero if self.max < -1: return FiniteSet(-oo, oo) return AccumBounds(-oo, oo) else: if self.min > -1: if self.max < 1: return S.Zero return AccumBounds(0, oo) return AccumBounds(-oo, oo) if other is S.NegativeInfinity: return (1 / self)**oo if other.is_real and other.is_number: if other.is_zero: return S.One if other.is_Integer: if self.min.is_positive: return AccumBounds( Min(self.min ** other, self.max ** other), Max(self.min ** other, self.max ** other)) elif self.max.is_negative: return AccumBounds( Min(self.max ** other, self.min ** other), Max(self.max ** other, self.min ** other)) if other % 2 == 0: if other.is_negative: if self.min.is_zero: return AccumBounds(self.max**other, oo) if self.max.is_zero: return AccumBounds(self.min**other, oo) return AccumBounds(0, oo) return AccumBounds( S.Zero, Max(self.min**other, self.max**other)) else: if other.is_negative: if self.min.is_zero: return AccumBounds(self.max**other, oo) if self.max.is_zero: return AccumBounds(-oo, self.min**other) return AccumBounds(-oo, oo) return AccumBounds(self.min**other, self.max**other) num, den = other.as_numer_denom() if num == S(1): if den % 2 == 0: if S.Zero in self: if self.min.is_negative: return AccumBounds(0, real_root(self.max, den)) return AccumBounds(real_root(self.min, den), real_root(self.max, den)) num_pow = self**num return num_pow**(1 / den) return Pow(self, other, evaluate=False) return NotImplemented def __abs__(self): if self.max.is_negative: return self.__neg__() elif self.min.is_negative: return AccumBounds(S.Zero, Max(abs(self.min), self.max)) else: return self def __lt__(self, other): """ Returns True if range of values attained by `self` AccumulationBounds object is less than the range of values attained by `other`, where other may be any value of type AccumulationBounds object or extended real number value, False if `other` satisfies the same property, else an unevaluated Relational Examples ======== >>> from sympy import AccumBounds, oo >>> AccumBounds(1, 3) < AccumBounds(4, oo) True >>> AccumBounds(1, 4) < AccumBounds(3, 4) AccumBounds(1, 4) < AccumBounds(3, 4) >>> AccumBounds(1, oo) < -1 False """ other = _sympify(other) if isinstance(other, AccumBounds): if self.max < other.min: return True if self.min >= other.max: return False elif not(other.is_real or other is S.Infinity or other is S.NegativeInfinity): raise TypeError( "Invalid comparison of %s %s" % (type(other), other)) elif other.is_comparable: if self.max < other: return True if self.min >= other: return False return super(AccumulationBounds, self).__lt__(other) def __le__(self, other): """ Returns True if range of values attained by `self` AccumulationBounds object is less than or equal to the range of values attained by `other`, where other may be any value of type AccumulationBounds object or extended real number value, False if `other` satisfies the same property, else an unevaluated Relational. Examples ======== >>> from sympy import AccumBounds, oo >>> AccumBounds(1, 3) <= AccumBounds(4, oo) True >>> AccumBounds(1, 4) <= AccumBounds(3, 4) AccumBounds(1, 4) <= AccumBounds(3, 4) >>> AccumBounds(1, 3) <= 0 False """ other = _sympify(other) if isinstance(other, AccumBounds): if self.max <= other.min: return True if self.min > other.max: return False elif not(other.is_real or other is S.Infinity or other is S.NegativeInfinity): raise TypeError( "Invalid comparison of %s %s" % (type(other), other)) elif other.is_comparable: if self.max <= other: return True if self.min > other: return False return super(AccumulationBounds, self).__le__(other) def __gt__(self, other): """ Returns True if range of values attained by `self` AccumulationBounds object is greater than the range of values attained by `other`, where other may be any value of type AccumulationBounds object or extended real number value, False if `other` satisfies the same property, else an unevaluated Relational. Examples ======== >>> from sympy import AccumBounds, oo >>> AccumBounds(1, 3) > AccumBounds(4, oo) False >>> AccumBounds(1, 4) > AccumBounds(3, 4) AccumBounds(1, 4) > AccumBounds(3, 4) >>> AccumBounds(1, oo) > -1 True """ other = _sympify(other) if isinstance(other, AccumBounds): if self.min > other.max: return True if self.max <= other.min: return False elif not(other.is_real or other is S.Infinity or other is S.NegativeInfinity): raise TypeError( "Invalid comparison of %s %s" % (type(other), other)) elif other.is_comparable: if self.min > other: return True if self.max <= other: return False return super(AccumulationBounds, self).__gt__(other) def __ge__(self, other): """ Returns True if range of values attained by `self` AccumulationBounds object is less that the range of values attained by `other`, where other may be any value of type AccumulationBounds object or extended real number value, False if `other` satisfies the same property, else an unevaluated Relational. Examples ======== >>> from sympy import AccumBounds, oo >>> AccumBounds(1, 3) >= AccumBounds(4, oo) False >>> AccumBounds(1, 4) >= AccumBounds(3, 4) AccumBounds(1, 4) >= AccumBounds(3, 4) >>> AccumBounds(1, oo) >= 1 True """ other = _sympify(other) if isinstance(other, AccumBounds): if self.min >= other.max: return True if self.max < other.min: return False elif not(other.is_real or other is S.Infinity or other is S.NegativeInfinity): raise TypeError( "Invalid comparison of %s %s" % (type(other), other)) elif other.is_comparable: if self.min >= other: return True if self.max < other: return False return super(AccumulationBounds, self).__ge__(other) def __contains__(self, other): """ Returns True if other is contained in self, where other belongs to extended real numbers, False if not contained, otherwise TypeError is raised. Examples ======== >>> from sympy import AccumBounds, oo >>> 1 in AccumBounds(-1, 3) True -oo and oo go together as limits (in AccumulationBounds). >>> -oo in AccumBounds(1, oo) True >>> oo in AccumBounds(-oo, 0) True """ other = _sympify(other) if other is S.Infinity or other is S.NegativeInfinity: if self.min is S.NegativeInfinity or self.max is S.Infinity: return True return False rv = And(self.min <= other, self.max >= other) if rv not in (True, False): raise TypeError("input failed to evaluate") return rv def intersection(self, other): """ Returns the intersection of 'self' and 'other'. Here other can be an instance of FiniteSet or AccumulationBounds. Examples ======== >>> from sympy import AccumBounds, FiniteSet >>> AccumBounds(1, 3).intersection(AccumBounds(2, 4)) AccumBounds(2, 3) >>> AccumBounds(1, 3).intersection(AccumBounds(4, 6)) EmptySet() >>> AccumBounds(1, 4).intersection(FiniteSet(1, 2, 5)) {1, 2} """ if not isinstance(other, (AccumBounds, FiniteSet)): raise TypeError( "Input must be AccumulationBounds or FiniteSet object") if isinstance(other, FiniteSet): fin_set = S.EmptySet for i in other: if i in self: fin_set = fin_set + FiniteSet(i) return fin_set if self.max < other.min or self.min > other.max: return S.EmptySet if self.min <= other.min: if self.max <= other.max: return AccumBounds(other.min, self.max) if self.max > other.max: return other if other.min <= self.min: if other.max < self.max: return AccumBounds(self.min, other.max) if other.max > self.max: return self def union(self, other): # TODO : Devise a better method for Union of AccumBounds # this method is not actually correct and # can be made better if not isinstance(other, AccumBounds): raise TypeError( "Input must be AccumulationBounds or FiniteSet object") if self.min <= other.min and self.max >= other.min: return AccumBounds(self.min, Max(self.max, other.max)) if other.min <= self.min and other.max >= self.min: return AccumBounds(other.min, Max(self.max, other.max)) # setting an alias for AccumulationBounds AccumBounds = AccumulationBounds

15d322f514f373221a11c72110ac941cc78b583198959644d8a6b96804813314

""" module for generating C, C++, Fortran77, Fortran90, Julia, Rust and Octave/Matlab routines that evaluate sympy expressions. This module is work in progress. Only the milestones with a '+' character in the list below have been completed. --- How is sympy.utilities.codegen different from sympy.printing.ccode? --- We considered the idea to extend the printing routines for sympy functions in such a way that it prints complete compilable code, but this leads to a few unsurmountable issues that can only be tackled with dedicated code generator: - For C, one needs both a code and a header file, while the printing routines generate just one string. This code generator can be extended to support .pyf files for f2py. - SymPy functions are not concerned with programming-technical issues, such as input, output and input-output arguments. Other examples are contiguous or non-contiguous arrays, including headers of other libraries such as gsl or others. - It is highly interesting to evaluate several sympy functions in one C routine, eventually sharing common intermediate results with the help of the cse routine. This is more than just printing. - From the programming perspective, expressions with constants should be evaluated in the code generator as much as possible. This is different for printing. --- Basic assumptions --- * A generic Routine data structure describes the routine that must be translated into C/Fortran/... code. This data structure covers all features present in one or more of the supported languages. * Descendants from the CodeGen class transform multiple Routine instances into compilable code. Each derived class translates into a specific language. * In many cases, one wants a simple workflow. The friendly functions in the last part are a simple api on top of the Routine/CodeGen stuff. They are easier to use, but are less powerful. --- Milestones --- + First working version with scalar input arguments, generating C code, tests + Friendly functions that are easier to use than the rigorous Routine/CodeGen workflow. + Integer and Real numbers as input and output + Output arguments + InputOutput arguments + Sort input/output arguments properly + Contiguous array arguments (numpy matrices) + Also generate .pyf code for f2py (in autowrap module) + Isolate constants and evaluate them beforehand in double precision + Fortran 90 + Octave/Matlab - Common Subexpression Elimination - User defined comments in the generated code - Optional extra include lines for libraries/objects that can eval special functions - Test other C compilers and libraries: gcc, tcc, libtcc, gcc+gsl, ... - Contiguous array arguments (sympy matrices) - Non-contiguous array arguments (sympy matrices) - ccode must raise an error when it encounters something that can not be translated into c. ccode(integrate(sin(x)/x, x)) does not make sense. - Complex numbers as input and output - A default complex datatype - Include extra information in the header: date, user, hostname, sha1 hash, ... - Fortran 77 - C++ - Python - Julia - Rust - ... """ from __future__ import print_function, division import os import textwrap from sympy import __version__ as sympy_version from sympy.core import Symbol, S, Tuple, Equality, Function, Basic from sympy.core.compatibility import is_sequence, StringIO, string_types from sympy.printing.ccode import c_code_printers from sympy.printing.codeprinter import AssignmentError from sympy.printing.fcode import FCodePrinter from sympy.printing.julia import JuliaCodePrinter from sympy.printing.octave import OctaveCodePrinter from sympy.printing.rust import RustCodePrinter from sympy.tensor import Idx, Indexed, IndexedBase from sympy.matrices import (MatrixSymbol, ImmutableMatrix, MatrixBase, MatrixExpr, MatrixSlice) __all__ = [ # description of routines "Routine", "DataType", "default_datatypes", "get_default_datatype", "Argument", "InputArgument", "OutputArgument", "Result", # routines -> code "CodeGen", "CCodeGen", "FCodeGen", "JuliaCodeGen", "OctaveCodeGen", "RustCodeGen", # friendly functions "codegen", "make_routine", ] # # Description of routines # class Routine(object): """Generic description of evaluation routine for set of expressions. A CodeGen class can translate instances of this class into code in a particular language. The routine specification covers all the features present in these languages. The CodeGen part must raise an exception when certain features are not present in the target language. For example, multiple return values are possible in Python, but not in C or Fortran. Another example: Fortran and Python support complex numbers, while C does not. """ def __init__(self, name, arguments, results, local_vars, global_vars): """Initialize a Routine instance. Parameters ========== name : string Name of the routine. arguments : list of Arguments These are things that appear in arguments of a routine, often appearing on the right-hand side of a function call. These are commonly InputArguments but in some languages, they can also be OutputArguments or InOutArguments (e.g., pass-by-reference in C code). results : list of Results These are the return values of the routine, often appearing on the left-hand side of a function call. The difference between Results and OutputArguments and when you should use each is language-specific. local_vars : list of Results These are variables that will be defined at the beginning of the function. global_vars : list of Symbols Variables which will not be passed into the function. """ # extract all input symbols and all symbols appearing in an expression input_symbols = set([]) symbols = set([]) for arg in arguments: if isinstance(arg, OutputArgument): symbols.update(arg.expr.free_symbols - arg.expr.atoms(Indexed)) elif isinstance(arg, InputArgument): input_symbols.add(arg.name) elif isinstance(arg, InOutArgument): input_symbols.add(arg.name) symbols.update(arg.expr.free_symbols - arg.expr.atoms(Indexed)) else: raise ValueError("Unknown Routine argument: %s" % arg) for r in results: if not isinstance(r, Result): raise ValueError("Unknown Routine result: %s" % r) symbols.update(r.expr.free_symbols - r.expr.atoms(Indexed)) local_symbols = set() for r in local_vars: if isinstance(r, Result): symbols.update(r.expr.free_symbols - r.expr.atoms(Indexed)) local_symbols.add(r.name) else: local_symbols.add(r) symbols = set([s.label if isinstance(s, Idx) else s for s in symbols]) # Check that all symbols in the expressions are covered by # InputArguments/InOutArguments---subset because user could # specify additional (unused) InputArguments or local_vars. notcovered = symbols.difference( input_symbols.union(local_symbols).union(global_vars)) if notcovered != set([]): raise ValueError("Symbols needed for output are not in input " + ", ".join([str(x) for x in notcovered])) self.name = name self.arguments = arguments self.results = results self.local_vars = local_vars self.global_vars = global_vars def __str__(self): return self.__class__.__name__ + "({name!r}, {arguments}, {results}, {local_vars}, {global_vars})".format(**self.__dict__) __repr__ = __str__ @property def variables(self): """Returns a set of all variables possibly used in the routine. For routines with unnamed return values, the dummies that may or may not be used will be included in the set. """ v = set(self.local_vars) for arg in self.arguments: v.add(arg.name) for res in self.results: v.add(res.result_var) return v @property def result_variables(self): """Returns a list of OutputArgument, InOutArgument and Result. If return values are present, they are at the end ot the list. """ args = [arg for arg in self.arguments if isinstance( arg, (OutputArgument, InOutArgument))] args.extend(self.results) return args class DataType(object): """Holds strings for a certain datatype in different languages.""" def __init__(self, cname, fname, pyname, jlname, octname, rsname): self.cname = cname self.fname = fname self.pyname = pyname self.jlname = jlname self.octname = octname self.rsname = rsname default_datatypes = { "int": DataType("int", "INTEGER*4", "int", "", "", "i32"), "float": DataType("double", "REAL*8", "float", "", "", "f64"), } def get_default_datatype(expr): """Derives an appropriate datatype based on the expression.""" if expr.is_integer: return default_datatypes["int"] elif isinstance(expr, MatrixBase): for element in expr: if not element.is_integer: return default_datatypes["float"] return default_datatypes["int"] else: return default_datatypes["float"] class Variable(object): """Represents a typed variable.""" def __init__(self, name, datatype=None, dimensions=None, precision=None): """Return a new variable. Parameters ========== name : Symbol or MatrixSymbol datatype : optional When not given, the data type will be guessed based on the assumptions on the symbol argument. dimension : sequence containing tupes, optional If present, the argument is interpreted as an array, where this sequence of tuples specifies (lower, upper) bounds for each index of the array. precision : int, optional Controls the precision of floating point constants. """ if not isinstance(name, (Symbol, MatrixSymbol)): raise TypeError("The first argument must be a sympy symbol.") if datatype is None: datatype = get_default_datatype(name) elif not isinstance(datatype, DataType): raise TypeError("The (optional) `datatype' argument must be an " "instance of the DataType class.") if dimensions and not isinstance(dimensions, (tuple, list)): raise TypeError( "The dimension argument must be a sequence of tuples") self._name = name self._datatype = { 'C': datatype.cname, 'FORTRAN': datatype.fname, 'JULIA': datatype.jlname, 'OCTAVE': datatype.octname, 'PYTHON': datatype.pyname, 'RUST': datatype.rsname, } self.dimensions = dimensions self.precision = precision def __str__(self): return "%s(%r)" % (self.__class__.__name__, self.name) __repr__ = __str__ @property def name(self): return self._name def get_datatype(self, language): """Returns the datatype string for the requested language. Examples ======== >>> from sympy import Symbol >>> from sympy.utilities.codegen import Variable >>> x = Variable(Symbol('x')) >>> x.get_datatype('c') 'double' >>> x.get_datatype('fortran') 'REAL*8' """ try: return self._datatype[language.upper()] except KeyError: raise CodeGenError("Has datatypes for languages: %s" % ", ".join(self._datatype)) class Argument(Variable): """An abstract Argument data structure: a name and a data type. This structure is refined in the descendants below. """ pass class InputArgument(Argument): pass class ResultBase(object): """Base class for all "outgoing" information from a routine. Objects of this class stores a sympy expression, and a sympy object representing a result variable that will be used in the generated code only if necessary. """ def __init__(self, expr, result_var): self.expr = expr self.result_var = result_var def __str__(self): return "%s(%r, %r)" % (self.__class__.__name__, self.expr, self.result_var) __repr__ = __str__ class OutputArgument(Argument, ResultBase): """OutputArgument are always initialized in the routine.""" def __init__(self, name, result_var, expr, datatype=None, dimensions=None, precision=None): """Return a new variable. Parameters ========== name : Symbol, MatrixSymbol The name of this variable. When used for code generation, this might appear, for example, in the prototype of function in the argument list. result_var : Symbol, Indexed Something that can be used to assign a value to this variable. Typically the same as `name` but for Indexed this should be e.g., "y[i]" whereas `name` should be the Symbol "y". expr : object The expression that should be output, typically a SymPy expression. datatype : optional When not given, the data type will be guessed based on the assumptions on the symbol argument. dimension : sequence containing tupes, optional If present, the argument is interpreted as an array, where this sequence of tuples specifies (lower, upper) bounds for each index of the array. precision : int, optional Controls the precision of floating point constants. """ Argument.__init__(self, name, datatype, dimensions, precision) ResultBase.__init__(self, expr, result_var) def __str__(self): return "%s(%r, %r, %r)" % (self.__class__.__name__, self.name, self.result_var, self.expr) __repr__ = __str__ class InOutArgument(Argument, ResultBase): """InOutArgument are never initialized in the routine.""" def __init__(self, name, result_var, expr, datatype=None, dimensions=None, precision=None): if not datatype: datatype = get_default_datatype(expr) Argument.__init__(self, name, datatype, dimensions, precision) ResultBase.__init__(self, expr, result_var) __init__.__doc__ = OutputArgument.__init__.__doc__ def __str__(self): return "%s(%r, %r, %r)" % (self.__class__.__name__, self.name, self.expr, self.result_var) __repr__ = __str__ class Result(Variable, ResultBase): """An expression for a return value. The name result is used to avoid conflicts with the reserved word "return" in the python language. It is also shorter than ReturnValue. These may or may not need a name in the destination (e.g., "return(x*y)" might return a value without ever naming it). """ def __init__(self, expr, name=None, result_var=None, datatype=None, dimensions=None, precision=None): """Initialize a return value. Parameters ========== expr : SymPy expression name : Symbol, MatrixSymbol, optional The name of this return variable. When used for code generation, this might appear, for example, in the prototype of function in a list of return values. A dummy name is generated if omitted. result_var : Symbol, Indexed, optional Something that can be used to assign a value to this variable. Typically the same as `name` but for Indexed this should be e.g., "y[i]" whereas `name` should be the Symbol "y". Defaults to `name` if omitted. datatype : optional When not given, the data type will be guessed based on the assumptions on the symbol argument. dimension : sequence containing tupes, optional If present, this variable is interpreted as an array, where this sequence of tuples specifies (lower, upper) bounds for each index of the array. precision : int, optional Controls the precision of floating point constants. """ # Basic because it is the base class for all types of expressions if not isinstance(expr, (Basic, MatrixBase)): raise TypeError("The first argument must be a sympy expression.") if name is None: name = 'result_%d' % abs(hash(expr)) if isinstance(name, string_types): if isinstance(expr, (MatrixBase, MatrixExpr)): name = MatrixSymbol(name, *expr.shape) else: name = Symbol(name) if result_var is None: result_var = name Variable.__init__(self, name, datatype=datatype, dimensions=dimensions, precision=precision) ResultBase.__init__(self, expr, result_var) def __str__(self): return "%s(%r, %r, %r)" % (self.__class__.__name__, self.expr, self.name, self.result_var) __repr__ = __str__ # # Transformation of routine objects into code # class CodeGen(object): """Abstract class for the code generators.""" printer = None # will be set to an instance of a CodePrinter subclass def _indent_code(self, codelines): return self.printer.indent_code(codelines) def _printer_method_with_settings(self, method, settings=None, *args, **kwargs): settings = settings or {} ori = {k: self.printer._settings[k] for k in settings} for k, v in settings.items(): self.printer._settings[k] = v result = getattr(self.printer, method)(*args, **kwargs) for k, v in ori.items(): self.printer._settings[k] = v return result def _get_symbol(self, s): """Returns the symbol as fcode prints it.""" if self.printer._settings['human']: expr_str = self.printer.doprint(s) else: constants, not_supported, expr_str = self.printer.doprint(s) if constants or not_supported: raise ValueError("Failed to print %s" % str(s)) return expr_str.strip() def __init__(self, project="project", cse=False): """Initialize a code generator. Derived classes will offer more options that affect the generated code. """ self.project = project self.cse = cse def routine(self, name, expr, argument_sequence=None, global_vars=None): """Creates an Routine object that is appropriate for this language. This implementation is appropriate for at least C/Fortran. Subclasses can override this if necessary. Here, we assume at most one return value (the l-value) which must be scalar. Additional outputs are OutputArguments (e.g., pointers on right-hand-side or pass-by-reference). Matrices are always returned via OutputArguments. If ``argument_sequence`` is None, arguments will be ordered alphabetically, but with all InputArguments first, and then OutputArgument and InOutArguments. """ if self.cse: from sympy.simplify.cse_main import cse if is_sequence(expr) and not isinstance(expr, (MatrixBase, MatrixExpr)): if not expr: raise ValueError("No expression given") for e in expr: if not e.is_Equality: raise CodeGenError("Lists of expressions must all be Equalities. {} is not.".format(e)) # create a list of right hand sides and simplify them rhs = [e.rhs for e in expr] common, simplified = cse(rhs) # pack the simplified expressions back up with their left hand sides expr = [Equality(e.lhs, rhs) for e, rhs in zip(expr, simplified)] else: rhs = [expr] if isinstance(expr, Equality): common, simplified = cse(expr.rhs) #, ignore=in_out_args) expr = Equality(expr.lhs, simplified[0]) else: common, simplified = cse(expr) expr = simplified local_vars = [Result(b,a) for a,b in common] local_symbols = set([a for a,_ in common]) local_expressions = Tuple(*[b for _,b in common]) else: local_expressions = Tuple() if is_sequence(expr) and not isinstance(expr, (MatrixBase, MatrixExpr)): if not expr: raise ValueError("No expression given") expressions = Tuple(*expr) else: expressions = Tuple(expr) if self.cse: if {i.label for i in expressions.atoms(Idx)} != set(): raise CodeGenError("CSE and Indexed expressions do not play well together yet") else: # local variables for indexed expressions local_vars = {i.label for i in expressions.atoms(Idx)} local_symbols = local_vars # global variables global_vars = set() if global_vars is None else set(global_vars) # symbols that should be arguments symbols = (expressions.free_symbols | local_expressions.free_symbols) - local_symbols - global_vars new_symbols = set([]) new_symbols.update(symbols) for symbol in symbols: if isinstance(symbol, Idx): new_symbols.remove(symbol) new_symbols.update(symbol.args[1].free_symbols) if isinstance(symbol, Indexed): new_symbols.remove(symbol) symbols = new_symbols # Decide whether to use output argument or return value return_val = [] output_args = [] for expr in expressions: if isinstance(expr, Equality): out_arg = expr.lhs expr = expr.rhs if isinstance(out_arg, Indexed): dims = tuple([ (S.Zero, dim - 1) for dim in out_arg.shape]) symbol = out_arg.base.label elif isinstance(out_arg, Symbol): dims = [] symbol = out_arg elif isinstance(out_arg, MatrixSymbol): dims = tuple([ (S.Zero, dim - 1) for dim in out_arg.shape]) symbol = out_arg else: raise CodeGenError("Only Indexed, Symbol, or MatrixSymbol " "can define output arguments.") if expr.has(symbol): output_args.append( InOutArgument(symbol, out_arg, expr, dimensions=dims)) else: output_args.append( OutputArgument(symbol, out_arg, expr, dimensions=dims)) # remove duplicate arguments when they are not local variables if symbol not in local_vars: # avoid duplicate arguments symbols.remove(symbol) elif isinstance(expr, (ImmutableMatrix, MatrixSlice)): # Create a "dummy" MatrixSymbol to use as the Output arg out_arg = MatrixSymbol('out_%s' % abs(hash(expr)), *expr.shape) dims = tuple([(S.Zero, dim - 1) for dim in out_arg.shape]) output_args.append( OutputArgument(out_arg, out_arg, expr, dimensions=dims)) else: return_val.append(Result(expr)) arg_list = [] # setup input argument list array_symbols = {} for array in expressions.atoms(Indexed) | local_expressions.atoms(Indexed): array_symbols[array.base.label] = array for array in expressions.atoms(MatrixSymbol) | local_expressions.atoms(MatrixSymbol): array_symbols[array] = array for symbol in sorted(symbols, key=str): if symbol in array_symbols: dims = [] array = array_symbols[symbol] for dim in array.shape: dims.append((S.Zero, dim - 1)) metadata = {'dimensions': dims} else: metadata = {} arg_list.append(InputArgument(symbol, **metadata)) output_args.sort(key=lambda x: str(x.name)) arg_list.extend(output_args) if argument_sequence is not None: # if the user has supplied IndexedBase instances, we'll accept that new_sequence = [] for arg in argument_sequence: if isinstance(arg, IndexedBase): new_sequence.append(arg.label) else: new_sequence.append(arg) argument_sequence = new_sequence missing = [x for x in arg_list if x.name not in argument_sequence] if missing: msg = "Argument list didn't specify: {0} " msg = msg.format(", ".join([str(m.name) for m in missing])) raise CodeGenArgumentListError(msg, missing) # create redundant arguments to produce the requested sequence name_arg_dict = {x.name: x for x in arg_list} new_args = [] for symbol in argument_sequence: try: new_args.append(name_arg_dict[symbol]) except KeyError: new_args.append(InputArgument(symbol)) arg_list = new_args return Routine(name, arg_list, return_val, local_vars, global_vars) def write(self, routines, prefix, to_files=False, header=True, empty=True): """Writes all the source code files for the given routines. The generated source is returned as a list of (filename, contents) tuples, or is written to files (see below). Each filename consists of the given prefix, appended with an appropriate extension. Parameters ========== routines : list A list of Routine instances to be written prefix : string The prefix for the output files to_files : bool, optional When True, the output is written to files. Otherwise, a list of (filename, contents) tuples is returned. [default: False] header : bool, optional When True, a header comment is included on top of each source file. [default: True] empty : bool, optional When True, empty lines are included to structure the source files. [default: True] """ if to_files: for dump_fn in self.dump_fns: filename = "%s.%s" % (prefix, dump_fn.extension) with open(filename, "w") as f: dump_fn(self, routines, f, prefix, header, empty) else: result = [] for dump_fn in self.dump_fns: filename = "%s.%s" % (prefix, dump_fn.extension) contents = StringIO() dump_fn(self, routines, contents, prefix, header, empty) result.append((filename, contents.getvalue())) return result def dump_code(self, routines, f, prefix, header=True, empty=True): """Write the code by calling language specific methods. The generated file contains all the definitions of the routines in low-level code and refers to the header file if appropriate. Parameters ========== routines : list A list of Routine instances. f : file-like Where to write the file. prefix : string The filename prefix, used to refer to the proper header file. Only the basename of the prefix is used. header : bool, optional When True, a header comment is included on top of each source file. [default : True] empty : bool, optional When True, empty lines are included to structure the source files. [default : True] """ code_lines = self._preprocessor_statements(prefix) for routine in routines: if empty: code_lines.append("\n") code_lines.extend(self._get_routine_opening(routine)) code_lines.extend(self._declare_arguments(routine)) code_lines.extend(self._declare_globals(routine)) code_lines.extend(self._declare_locals(routine)) if empty: code_lines.append("\n") code_lines.extend(self._call_printer(routine)) if empty: code_lines.append("\n") code_lines.extend(self._get_routine_ending(routine)) code_lines = self._indent_code(''.join(code_lines)) if header: code_lines = ''.join(self._get_header() + [code_lines]) if code_lines: f.write(code_lines) class CodeGenError(Exception): pass class CodeGenArgumentListError(Exception): @property def missing_args(self): return self.args[1] header_comment = """Code generated with sympy %(version)s See http://www.sympy.org/ for more information. This file is part of '%(project)s' """ class CCodeGen(CodeGen): """Generator for C code. The .write() method inherited from CodeGen will output a code file and an interface file, <prefix>.c and <prefix>.h respectively. """ code_extension = "c" interface_extension = "h" standard = 'c99' def __init__(self, project="project", printer=None, preprocessor_statements=None, cse=False): super(CCodeGen, self).__init__(project=project, cse=cse) self.printer = printer or c_code_printers[self.standard.lower()]() self.preprocessor_statements = preprocessor_statements if preprocessor_statements is None: self.preprocessor_statements = ['#include <math.h>'] def _get_header(self): """Writes a common header for the generated files.""" code_lines = [] code_lines.append("/" + "*"*78 + '\n') tmp = header_comment % {"version": sympy_version, "project": self.project} for line in tmp.splitlines(): code_lines.append(" *%s*\n" % line.center(76)) code_lines.append(" " + "*"*78 + "/\n") return code_lines def get_prototype(self, routine): """Returns a string for the function prototype of the routine. If the routine has multiple result objects, an CodeGenError is raised. See: https://en.wikipedia.org/wiki/Function_prototype """ if len(routine.results) > 1: raise CodeGenError("C only supports a single or no return value.") elif len(routine.results) == 1: ctype = routine.results[0].get_datatype('C') else: ctype = "void" type_args = [] for arg in routine.arguments: name = self.printer.doprint(arg.name) if arg.dimensions or isinstance(arg, ResultBase): type_args.append((arg.get_datatype('C'), "*%s" % name)) else: type_args.append((arg.get_datatype('C'), name)) arguments = ", ".join([ "%s %s" % t for t in type_args]) return "%s %s(%s)" % (ctype, routine.name, arguments) def _preprocessor_statements(self, prefix): code_lines = [] code_lines.append('#include "{}.h"'.format(os.path.basename(prefix))) code_lines.extend(self.preprocessor_statements) code_lines = ['{}\n'.format(l) for l in code_lines] return code_lines def _get_routine_opening(self, routine): prototype = self.get_prototype(routine) return ["%s {\n" % prototype] def _declare_arguments(self, routine): # arguments are declared in prototype return [] def _declare_globals(self, routine): # global variables are not explicitly declared within C functions return [] def _declare_locals(self, routine): # Compose a list of symbols to be dereferenced in the function # body. These are the arguments that were passed by a reference # pointer, excluding arrays. dereference = [] for arg in routine.arguments: if isinstance(arg, ResultBase) and not arg.dimensions: dereference.append(arg.name) code_lines = [] for result in routine.local_vars: # local variables that are simple symbols such as those used as indices into # for loops are defined declared elsewhere. if not isinstance(result, Result): continue if result.name != result.result_var: raise CodeGen("Result variable and name should match: {}".format(result)) assign_to = result.name t = result.get_datatype('c') if isinstance(result.expr, (MatrixBase, MatrixExpr)): dims = result.expr.shape if dims[1] != 1: raise CodeGenError("Only column vectors are supported in local variabels. Local result {} has dimensions {}".format(result, dims)) code_lines.append("{0} {1}[{2}];\n".format(t, str(assign_to), dims[0])) prefix = "" else: prefix = "const {0} ".format(t) constants, not_c, c_expr = self._printer_method_with_settings( 'doprint', dict(human=False, dereference=dereference), result.expr, assign_to=assign_to) for name, value in sorted(constants, key=str): code_lines.append("double const %s = %s;\n" % (name, value)) code_lines.append("{}{}\n".format(prefix, c_expr)) return code_lines def _call_printer(self, routine): code_lines = [] # Compose a list of symbols to be dereferenced in the function # body. These are the arguments that were passed by a reference # pointer, excluding arrays. dereference = [] for arg in routine.arguments: if isinstance(arg, ResultBase) and not arg.dimensions: dereference.append(arg.name) return_val = None for result in routine.result_variables: if isinstance(result, Result): assign_to = routine.name + "_result" t = result.get_datatype('c') code_lines.append("{0} {1};\n".format(t, str(assign_to))) return_val = assign_to else: assign_to = result.result_var try: constants, not_c, c_expr = self._printer_method_with_settings( 'doprint', dict(human=False, dereference=dereference), result.expr, assign_to=assign_to) except AssignmentError: assign_to = result.result_var code_lines.append( "%s %s;\n" % (result.get_datatype('c'), str(assign_to))) constants, not_c, c_expr = self._printer_method_with_settings( 'doprint', dict(human=False, dereference=dereference), result.expr, assign_to=assign_to) for name, value in sorted(constants, key=str): code_lines.append("double const %s = %s;\n" % (name, value)) code_lines.append("%s\n" % c_expr) if return_val: code_lines.append(" return %s;\n" % return_val) return code_lines def _get_routine_ending(self, routine): return ["}\n"] def dump_c(self, routines, f, prefix, header=True, empty=True): self.dump_code(routines, f, prefix, header, empty) dump_c.extension = code_extension dump_c.__doc__ = CodeGen.dump_code.__doc__ def dump_h(self, routines, f, prefix, header=True, empty=True): """Writes the C header file. This file contains all the function declarations. Parameters ========== routines : list A list of Routine instances. f : file-like Where to write the file. prefix : string The filename prefix, used to construct the include guards. Only the basename of the prefix is used. header : bool, optional When True, a header comment is included on top of each source file. [default : True] empty : bool, optional When True, empty lines are included to structure the source files. [default : True] """ if header: print(''.join(self._get_header()), file=f) guard_name = "%s__%s__H" % (self.project.replace( " ", "_").upper(), prefix.replace("/", "_").upper()) # include guards if empty: print(file=f) print("#ifndef %s" % guard_name, file=f) print("#define %s" % guard_name, file=f) if empty: print(file=f) # declaration of the function prototypes for routine in routines: prototype = self.get_prototype(routine) print("%s;" % prototype, file=f) # end if include guards if empty: print(file=f) print("#endif", file=f) if empty: print(file=f) dump_h.extension = interface_extension # This list of dump functions is used by CodeGen.write to know which dump # functions it has to call. dump_fns = [dump_c, dump_h] class C89CodeGen(CCodeGen): standard = 'C89' class C99CodeGen(CCodeGen): standard = 'C99' class FCodeGen(CodeGen): """Generator for Fortran 95 code The .write() method inherited from CodeGen will output a code file and an interface file, <prefix>.f90 and <prefix>.h respectively. """ code_extension = "f90" interface_extension = "h" def __init__(self, project='project', printer=None): super(FCodeGen, self).__init__(project) self.printer = printer or FCodePrinter() def _get_header(self): """Writes a common header for the generated files.""" code_lines = [] code_lines.append("!" + "*"*78 + '\n') tmp = header_comment % {"version": sympy_version, "project": self.project} for line in tmp.splitlines(): code_lines.append("!*%s*\n" % line.center(76)) code_lines.append("!" + "*"*78 + '\n') return code_lines def _preprocessor_statements(self, prefix): return [] def _get_routine_opening(self, routine): """Returns the opening statements of the fortran routine.""" code_list = [] if len(routine.results) > 1: raise CodeGenError( "Fortran only supports a single or no return value.") elif len(routine.results) == 1: result = routine.results[0] code_list.append(result.get_datatype('fortran')) code_list.append("function") else: code_list.append("subroutine") args = ", ".join("%s" % self._get_symbol(arg.name) for arg in routine.arguments) call_sig = "{0}({1})\n".format(routine.name, args) # Fortran 95 requires all lines be less than 132 characters, so wrap # this line before appending. call_sig = ' &\n'.join(textwrap.wrap(call_sig, width=60, break_long_words=False)) + '\n' code_list.append(call_sig) code_list = [' '.join(code_list)] code_list.append('implicit none\n') return code_list def _declare_arguments(self, routine): # argument type declarations code_list = [] array_list = [] scalar_list = [] for arg in routine.arguments: if isinstance(arg, InputArgument): typeinfo = "%s, intent(in)" % arg.get_datatype('fortran') elif isinstance(arg, InOutArgument): typeinfo = "%s, intent(inout)" % arg.get_datatype('fortran') elif isinstance(arg, OutputArgument): typeinfo = "%s, intent(out)" % arg.get_datatype('fortran') else: raise CodeGenError("Unknown Argument type: %s" % type(arg)) fprint = self._get_symbol if arg.dimensions: # fortran arrays start at 1 dimstr = ", ".join(["%s:%s" % ( fprint(dim[0] + 1), fprint(dim[1] + 1)) for dim in arg.dimensions]) typeinfo += ", dimension(%s)" % dimstr array_list.append("%s :: %s\n" % (typeinfo, fprint(arg.name))) else: scalar_list.append("%s :: %s\n" % (typeinfo, fprint(arg.name))) # scalars first, because they can be used in array declarations code_list.extend(scalar_list) code_list.extend(array_list) return code_list def _declare_globals(self, routine): # Global variables not explicitly declared within Fortran 90 functions. # Note: a future F77 mode may need to generate "common" blocks. return [] def _declare_locals(self, routine): code_list = [] for var in sorted(routine.local_vars, key=str): typeinfo = get_default_datatype(var) code_list.append("%s :: %s\n" % ( typeinfo.fname, self._get_symbol(var))) return code_list def _get_routine_ending(self, routine): """Returns the closing statements of the fortran routine.""" if len(routine.results) == 1: return ["end function\n"] else: return ["end subroutine\n"] def get_interface(self, routine): """Returns a string for the function interface. The routine should have a single result object, which can be None. If the routine has multiple result objects, a CodeGenError is raised. See: https://en.wikipedia.org/wiki/Function_prototype """ prototype = [ "interface\n" ] prototype.extend(self._get_routine_opening(routine)) prototype.extend(self._declare_arguments(routine)) prototype.extend(self._get_routine_ending(routine)) prototype.append("end interface\n") return "".join(prototype) def _call_printer(self, routine): declarations = [] code_lines = [] for result in routine.result_variables: if isinstance(result, Result): assign_to = routine.name elif isinstance(result, (OutputArgument, InOutArgument)): assign_to = result.result_var constants, not_fortran, f_expr = self._printer_method_with_settings( 'doprint', dict(human=False, source_format='free', standard=95), result.expr, assign_to=assign_to) for obj, v in sorted(constants, key=str): t = get_default_datatype(obj) declarations.append( "%s, parameter :: %s = %s\n" % (t.fname, obj, v)) for obj in sorted(not_fortran, key=str): t = get_default_datatype(obj) if isinstance(obj, Function): name = obj.func else: name = obj declarations.append("%s :: %s\n" % (t.fname, name)) code_lines.append("%s\n" % f_expr) return declarations + code_lines def _indent_code(self, codelines): return self._printer_method_with_settings( 'indent_code', dict(human=False, source_format='free'), codelines) def dump_f95(self, routines, f, prefix, header=True, empty=True): # check that symbols are unique with ignorecase for r in routines: lowercase = {str(x).lower() for x in r.variables} orig_case = {str(x) for x in r.variables} if len(lowercase) < len(orig_case): raise CodeGenError("Fortran ignores case. Got symbols: %s" % (", ".join([str(var) for var in r.variables]))) self.dump_code(routines, f, prefix, header, empty) dump_f95.extension = code_extension dump_f95.__doc__ = CodeGen.dump_code.__doc__ def dump_h(self, routines, f, prefix, header=True, empty=True): """Writes the interface to a header file. This file contains all the function declarations. Parameters ========== routines : list A list of Routine instances. f : file-like Where to write the file. prefix : string The filename prefix. header : bool, optional When True, a header comment is included on top of each source file. [default : True] empty : bool, optional When True, empty lines are included to structure the source files. [default : True] """ if header: print(''.join(self._get_header()), file=f) if empty: print(file=f) # declaration of the function prototypes for routine in routines: prototype = self.get_interface(routine) f.write(prototype) if empty: print(file=f) dump_h.extension = interface_extension # This list of dump functions is used by CodeGen.write to know which dump # functions it has to call. dump_fns = [dump_f95, dump_h] class JuliaCodeGen(CodeGen): """Generator for Julia code. The .write() method inherited from CodeGen will output a code file <prefix>.jl. """ code_extension = "jl" def __init__(self, project='project', printer=None): super(JuliaCodeGen, self).__init__(project) self.printer = printer or JuliaCodePrinter() def routine(self, name, expr, argument_sequence, global_vars): """Specialized Routine creation for Julia.""" if is_sequence(expr) and not isinstance(expr, (MatrixBase, MatrixExpr)): if not expr: raise ValueError("No expression given") expressions = Tuple(*expr) else: expressions = Tuple(expr) # local variables local_vars = {i.label for i in expressions.atoms(Idx)} # global variables global_vars = set() if global_vars is None else set(global_vars) # symbols that should be arguments old_symbols = expressions.free_symbols - local_vars - global_vars symbols = set([]) for s in old_symbols: if isinstance(s, Idx): symbols.update(s.args[1].free_symbols) elif not isinstance(s, Indexed): symbols.add(s) # Julia supports multiple return values return_vals = [] output_args = [] for (i, expr) in enumerate(expressions): if isinstance(expr, Equality): out_arg = expr.lhs expr = expr.rhs symbol = out_arg if isinstance(out_arg, Indexed): dims = tuple([ (S.One, dim) for dim in out_arg.shape]) symbol = out_arg.base.label output_args.append(InOutArgument(symbol, out_arg, expr, dimensions=dims)) if not isinstance(out_arg, (Indexed, Symbol, MatrixSymbol)): raise CodeGenError("Only Indexed, Symbol, or MatrixSymbol " "can define output arguments.") return_vals.append(Result(expr, name=symbol, result_var=out_arg)) if not expr.has(symbol): # this is a pure output: remove from the symbols list, so # it doesn't become an input. symbols.remove(symbol) else: # we have no name for this output return_vals.append(Result(expr, name='out%d' % (i+1))) # setup input argument list output_args.sort(key=lambda x: str(x.name)) arg_list = list(output_args) array_symbols = {} for array in expressions.atoms(Indexed): array_symbols[array.base.label] = array for array in expressions.atoms(MatrixSymbol): array_symbols[array] = array for symbol in sorted(symbols, key=str): arg_list.append(InputArgument(symbol)) if argument_sequence is not None: # if the user has supplied IndexedBase instances, we'll accept that new_sequence = [] for arg in argument_sequence: if isinstance(arg, IndexedBase): new_sequence.append(arg.label) else: new_sequence.append(arg) argument_sequence = new_sequence missing = [x for x in arg_list if x.name not in argument_sequence] if missing: msg = "Argument list didn't specify: {0} " msg = msg.format(", ".join([str(m.name) for m in missing])) raise CodeGenArgumentListError(msg, missing) # create redundant arguments to produce the requested sequence name_arg_dict = {x.name: x for x in arg_list} new_args = [] for symbol in argument_sequence: try: new_args.append(name_arg_dict[symbol]) except KeyError: new_args.append(InputArgument(symbol)) arg_list = new_args return Routine(name, arg_list, return_vals, local_vars, global_vars) def _get_header(self): """Writes a common header for the generated files.""" code_lines = [] tmp = header_comment % {"version": sympy_version, "project": self.project} for line in tmp.splitlines(): if line == '': code_lines.append("#\n") else: code_lines.append("# %s\n" % line) return code_lines def _preprocessor_statements(self, prefix): return [] def _get_routine_opening(self, routine): """Returns the opening statements of the routine.""" code_list = [] code_list.append("function ") # Inputs args = [] for i, arg in enumerate(routine.arguments): if isinstance(arg, OutputArgument): raise CodeGenError("Julia: invalid argument of type %s" % str(type(arg))) if isinstance(arg, (InputArgument, InOutArgument)): args.append("%s" % self._get_symbol(arg.name)) args = ", ".join(args) code_list.append("%s(%s)\n" % (routine.name, args)) code_list = [ "".join(code_list) ] return code_list def _declare_arguments(self, routine): return [] def _declare_globals(self, routine): return [] def _declare_locals(self, routine): return [] def _get_routine_ending(self, routine): outs = [] for result in routine.results: if isinstance(result, Result): # Note: name not result_var; want `y` not `y[i]` for Indexed s = self._get_symbol(result.name) else: raise CodeGenError("unexpected object in Routine results") outs.append(s) return ["return " + ", ".join(outs) + "\nend\n"] def _call_printer(self, routine): declarations = [] code_lines = [] for i, result in enumerate(routine.results): if isinstance(result, Result): assign_to = result.result_var else: raise CodeGenError("unexpected object in Routine results") constants, not_supported, jl_expr = self._printer_method_with_settings( 'doprint', dict(human=False), result.expr, assign_to=assign_to) for obj, v in sorted(constants, key=str): declarations.append( "%s = %s\n" % (obj, v)) for obj in sorted(not_supported, key=str): if isinstance(obj, Function): name = obj.func else: name = obj declarations.append( "# unsupported: %s\n" % (name)) code_lines.append("%s\n" % (jl_expr)) return declarations + code_lines def _indent_code(self, codelines): # Note that indenting seems to happen twice, first # statement-by-statement by JuliaPrinter then again here. p = JuliaCodePrinter({'human': False}) return p.indent_code(codelines) def dump_jl(self, routines, f, prefix, header=True, empty=True): self.dump_code(routines, f, prefix, header, empty) dump_jl.extension = code_extension dump_jl.__doc__ = CodeGen.dump_code.__doc__ # This list of dump functions is used by CodeGen.write to know which dump # functions it has to call. dump_fns = [dump_jl] class OctaveCodeGen(CodeGen): """Generator for Octave code. The .write() method inherited from CodeGen will output a code file <prefix>.m. Octave .m files usually contain one function. That function name should match the filename (``prefix``). If you pass multiple ``name_expr`` pairs, the latter ones are presumed to be private functions accessed by the primary function. You should only pass inputs to ``argument_sequence``: outputs are ordered according to their order in ``name_expr``. """ code_extension = "m" def __init__(self, project='project', printer=None): super(OctaveCodeGen, self).__init__(project) self.printer = printer or OctaveCodePrinter() def routine(self, name, expr, argument_sequence, global_vars): """Specialized Routine creation for Octave.""" # FIXME: this is probably general enough for other high-level # languages, perhaps its the C/Fortran one that is specialized! if is_sequence(expr) and not isinstance(expr, (MatrixBase, MatrixExpr)): if not expr: raise ValueError("No expression given") expressions = Tuple(*expr) else: expressions = Tuple(expr) # local variables local_vars = {i.label for i in expressions.atoms(Idx)} # global variables global_vars = set() if global_vars is None else set(global_vars) # symbols that should be arguments old_symbols = expressions.free_symbols - local_vars - global_vars symbols = set([]) for s in old_symbols: if isinstance(s, Idx): symbols.update(s.args[1].free_symbols) elif not isinstance(s, Indexed): symbols.add(s) # Octave supports multiple return values return_vals = [] for (i, expr) in enumerate(expressions): if isinstance(expr, Equality): out_arg = expr.lhs expr = expr.rhs symbol = out_arg if isinstance(out_arg, Indexed): symbol = out_arg.base.label if not isinstance(out_arg, (Indexed, Symbol, MatrixSymbol)): raise CodeGenError("Only Indexed, Symbol, or MatrixSymbol " "can define output arguments.") return_vals.append(Result(expr, name=symbol, result_var=out_arg)) if not expr.has(symbol): # this is a pure output: remove from the symbols list, so # it doesn't become an input. symbols.remove(symbol) else: # we have no name for this output return_vals.append(Result(expr, name='out%d' % (i+1))) # setup input argument list arg_list = [] array_symbols = {} for array in expressions.atoms(Indexed): array_symbols[array.base.label] = array for array in expressions.atoms(MatrixSymbol): array_symbols[array] = array for symbol in sorted(symbols, key=str): arg_list.append(InputArgument(symbol)) if argument_sequence is not None: # if the user has supplied IndexedBase instances, we'll accept that new_sequence = [] for arg in argument_sequence: if isinstance(arg, IndexedBase): new_sequence.append(arg.label) else: new_sequence.append(arg) argument_sequence = new_sequence missing = [x for x in arg_list if x.name not in argument_sequence] if missing: msg = "Argument list didn't specify: {0} " msg = msg.format(", ".join([str(m.name) for m in missing])) raise CodeGenArgumentListError(msg, missing) # create redundant arguments to produce the requested sequence name_arg_dict = {x.name: x for x in arg_list} new_args = [] for symbol in argument_sequence: try: new_args.append(name_arg_dict[symbol]) except KeyError: new_args.append(InputArgument(symbol)) arg_list = new_args return Routine(name, arg_list, return_vals, local_vars, global_vars) def _get_header(self): """Writes a common header for the generated files.""" code_lines = [] tmp = header_comment % {"version": sympy_version, "project": self.project} for line in tmp.splitlines(): if line == '': code_lines.append("%\n") else: code_lines.append("%% %s\n" % line) return code_lines def _preprocessor_statements(self, prefix): return [] def _get_routine_opening(self, routine): """Returns the opening statements of the routine.""" code_list = [] code_list.append("function ") # Outputs outs = [] for i, result in enumerate(routine.results): if isinstance(result, Result): # Note: name not result_var; want `y` not `y(i)` for Indexed s = self._get_symbol(result.name) else: raise CodeGenError("unexpected object in Routine results") outs.append(s) if len(outs) > 1: code_list.append("[" + (", ".join(outs)) + "]") else: code_list.append("".join(outs)) code_list.append(" = ") # Inputs args = [] for i, arg in enumerate(routine.arguments): if isinstance(arg, (OutputArgument, InOutArgument)): raise CodeGenError("Octave: invalid argument of type %s" % str(type(arg))) if isinstance(arg, InputArgument): args.append("%s" % self._get_symbol(arg.name)) args = ", ".join(args) code_list.append("%s(%s)\n" % (routine.name, args)) code_list = [ "".join(code_list) ] return code_list def _declare_arguments(self, routine): return [] def _declare_globals(self, routine): if not routine.global_vars: return [] s = " ".join(sorted([self._get_symbol(g) for g in routine.global_vars])) return ["global " + s + "\n"] def _declare_locals(self, routine): return [] def _get_routine_ending(self, routine): return ["end\n"] def _call_printer(self, routine): declarations = [] code_lines = [] for i, result in enumerate(routine.results): if isinstance(result, Result): assign_to = result.result_var else: raise CodeGenError("unexpected object in Routine results") constants, not_supported, oct_expr = self._printer_method_with_settings( 'doprint', dict(human=False), result.expr, assign_to=assign_to) for obj, v in sorted(constants, key=str): declarations.append( " %s = %s; %% constant\n" % (obj, v)) for obj in sorted(not_supported, key=str): if isinstance(obj, Function): name = obj.func else: name = obj declarations.append( " %% unsupported: %s\n" % (name)) code_lines.append("%s\n" % (oct_expr)) return declarations + code_lines def _indent_code(self, codelines): return self._printer_method_with_settings( 'indent_code', dict(human=False), codelines) def dump_m(self, routines, f, prefix, header=True, empty=True, inline=True): # Note used to call self.dump_code() but we need more control for header code_lines = self._preprocessor_statements(prefix) for i, routine in enumerate(routines): if i > 0: if empty: code_lines.append("\n") code_lines.extend(self._get_routine_opening(routine)) if i == 0: if routine.name != prefix: raise ValueError('Octave function name should match prefix') if header: code_lines.append("%" + prefix.upper() + " Autogenerated by sympy\n") code_lines.append(''.join(self._get_header())) code_lines.extend(self._declare_arguments(routine)) code_lines.extend(self._declare_globals(routine)) code_lines.extend(self._declare_locals(routine)) if empty: code_lines.append("\n") code_lines.extend(self._call_printer(routine)) if empty: code_lines.append("\n") code_lines.extend(self._get_routine_ending(routine)) code_lines = self._indent_code(''.join(code_lines)) if code_lines: f.write(code_lines) dump_m.extension = code_extension dump_m.__doc__ = CodeGen.dump_code.__doc__ # This list of dump functions is used by CodeGen.write to know which dump # functions it has to call. dump_fns = [dump_m] class RustCodeGen(CodeGen): """Generator for Rust code. The .write() method inherited from CodeGen will output a code file <prefix>.rs """ code_extension = "rs" def __init__(self, project="project", printer=None): super(RustCodeGen, self).__init__(project=project) self.printer = printer or RustCodePrinter() def routine(self, name, expr, argument_sequence, global_vars): """Specialized Routine creation for Rust.""" if is_sequence(expr) and not isinstance(expr, (MatrixBase, MatrixExpr)): if not expr: raise ValueError("No expression given") expressions = Tuple(*expr) else: expressions = Tuple(expr) # local variables local_vars = set([i.label for i in expressions.atoms(Idx)]) # global variables global_vars = set() if global_vars is None else set(global_vars) # symbols that should be arguments symbols = expressions.free_symbols - local_vars - global_vars - expressions.atoms(Indexed) # Rust supports multiple return values return_vals = [] output_args = [] for (i, expr) in enumerate(expressions): if isinstance(expr, Equality): out_arg = expr.lhs expr = expr.rhs symbol = out_arg if isinstance(out_arg, Indexed): dims = tuple([ (S.One, dim) for dim in out_arg.shape]) symbol = out_arg.base.label output_args.append(InOutArgument(symbol, out_arg, expr, dimensions=dims)) if not isinstance(out_arg, (Indexed, Symbol, MatrixSymbol)): raise CodeGenError("Only Indexed, Symbol, or MatrixSymbol " "can define output arguments.") return_vals.append(Result(expr, name=symbol, result_var=out_arg)) if not expr.has(symbol): # this is a pure output: remove from the symbols list, so # it doesn't become an input. symbols.remove(symbol) else: # we have no name for this output return_vals.append(Result(expr, name='out%d' % (i+1))) # setup input argument list output_args.sort(key=lambda x: str(x.name)) arg_list = list(output_args) array_symbols = {} for array in expressions.atoms(Indexed): array_symbols[array.base.label] = array for array in expressions.atoms(MatrixSymbol): array_symbols[array] = array for symbol in sorted(symbols, key=str): arg_list.append(InputArgument(symbol)) if argument_sequence is not None: # if the user has supplied IndexedBase instances, we'll accept that new_sequence = [] for arg in argument_sequence: if isinstance(arg, IndexedBase): new_sequence.append(arg.label) else: new_sequence.append(arg) argument_sequence = new_sequence missing = [x for x in arg_list if x.name not in argument_sequence] if missing: msg = "Argument list didn't specify: {0} " msg = msg.format(", ".join([str(m.name) for m in missing])) raise CodeGenArgumentListError(msg, missing) # create redundant arguments to produce the requested sequence name_arg_dict = dict([(x.name, x) for x in arg_list]) new_args = [] for symbol in argument_sequence: try: new_args.append(name_arg_dict[symbol]) except KeyError: new_args.append(InputArgument(symbol)) arg_list = new_args return Routine(name, arg_list, return_vals, local_vars, global_vars) def _get_header(self): """Writes a common header for the generated files.""" code_lines = [] code_lines.append("/*\n") tmp = header_comment % {"version": sympy_version, "project": self.project} for line in tmp.splitlines(): code_lines.append((" *%s" % line.center(76)).rstrip() + "\n") code_lines.append(" */\n") return code_lines def get_prototype(self, routine): """Returns a string for the function prototype of the routine. If the routine has multiple result objects, an CodeGenError is raised. See: https://en.wikipedia.org/wiki/Function_prototype """ results = [i.get_datatype('Rust') for i in routine.results] if len(results) == 1: rstype = " -> " + results[0] elif len(routine.results) > 1: rstype = " -> (" + ", ".join(results) + ")" else: rstype = "" type_args = [] for arg in routine.arguments: name = self.printer.doprint(arg.name) if arg.dimensions or isinstance(arg, ResultBase): type_args.append(("*%s" % name, arg.get_datatype('Rust'))) else: type_args.append((name, arg.get_datatype('Rust'))) arguments = ", ".join([ "%s: %s" % t for t in type_args]) return "fn %s(%s)%s" % (routine.name, arguments, rstype) def _preprocessor_statements(self, prefix): code_lines = [] # code_lines.append("use std::f64::consts::*;\n") return code_lines def _get_routine_opening(self, routine): prototype = self.get_prototype(routine) return ["%s {\n" % prototype] def _declare_arguments(self, routine): # arguments are declared in prototype return [] def _declare_globals(self, routine): # global variables are not explicitly declared within C functions return [] def _declare_locals(self, routine): # loop variables are declared in loop statement return [] def _call_printer(self, routine): code_lines = [] declarations = [] returns = [] # Compose a list of symbols to be dereferenced in the function # body. These are the arguments that were passed by a reference # pointer, excluding arrays. dereference = [] for arg in routine.arguments: if isinstance(arg, ResultBase) and not arg.dimensions: dereference.append(arg.name) for i, result in enumerate(routine.results): if isinstance(result, Result): assign_to = result.result_var returns.append(str(result.result_var)) else: raise CodeGenError("unexpected object in Routine results") constants, not_supported, rs_expr = self._printer_method_with_settings( 'doprint', dict(human=False), result.expr, assign_to=assign_to) for name, value in sorted(constants, key=str): declarations.append("const %s: f64 = %s;\n" % (name, value)) for obj in sorted(not_supported, key=str): if isinstance(obj, Function): name = obj.func else: name = obj declarations.append("// unsupported: %s\n" % (name)) code_lines.append("let %s\n" % rs_expr); if len(returns) > 1: returns = ['(' + ', '.join(returns) + ')'] returns.append('\n') return declarations + code_lines + returns def _get_routine_ending(self, routine): return ["}\n"] def dump_rs(self, routines, f, prefix, header=True, empty=True): self.dump_code(routines, f, prefix, header, empty) dump_rs.extension = code_extension dump_rs.__doc__ = CodeGen.dump_code.__doc__ # This list of dump functions is used by CodeGen.write to know which dump # functions it has to call. dump_fns = [dump_rs] def get_code_generator(language, project=None, standard=None, printer = None): if language == 'C': if standard is None: pass elif standard.lower() == 'c89': language = 'C89' elif standard.lower() == 'c99': language = 'C99' CodeGenClass = {"C": CCodeGen, "C89": C89CodeGen, "C99": C99CodeGen, "F95": FCodeGen, "JULIA": JuliaCodeGen, "OCTAVE": OctaveCodeGen, "RUST": RustCodeGen}.get(language.upper()) if CodeGenClass is None: raise ValueError("Language '%s' is not supported." % language) return CodeGenClass(project, printer) # # Friendly functions # def codegen(name_expr, language=None, prefix=None, project="project", to_files=False, header=True, empty=True, argument_sequence=None, global_vars=None, standard=None, code_gen=None, printer = None): """Generate source code for expressions in a given language. Parameters ========== name_expr : tuple, or list of tuples A single (name, expression) tuple or a list of (name, expression) tuples. Each tuple corresponds to a routine. If the expression is an equality (an instance of class Equality) the left hand side is considered an output argument. If expression is an iterable, then the routine will have multiple outputs. language : string, A string that indicates the source code language. This is case insensitive. Currently, 'C', 'F95' and 'Octave' are supported. 'Octave' generates code compatible with both Octave and Matlab. prefix : string, optional A prefix for the names of the files that contain the source code. Language-dependent suffixes will be appended. If omitted, the name of the first name_expr tuple is used. project : string, optional A project name, used for making unique preprocessor instructions. [default: "project"] to_files : bool, optional When True, the code will be written to one or more files with the given prefix, otherwise strings with the names and contents of these files are returned. [default: False] header : bool, optional When True, a header is written on top of each source file. [default: True] empty : bool, optional When True, empty lines are used to structure the code. [default: True] argument_sequence : iterable, optional Sequence of arguments for the routine in a preferred order. A CodeGenError is raised if required arguments are missing. Redundant arguments are used without warning. If omitted, arguments will be ordered alphabetically, but with all input arguments first, and then output or in-out arguments. global_vars : iterable, optional Sequence of global variables used by the routine. Variables listed here will not show up as function arguments. standard : string code_gen : CodeGen instance An instance of a CodeGen subclass. Overrides ``language``. Examples ======== >>> from sympy.utilities.codegen import codegen >>> from sympy.abc import x, y, z >>> [(c_name, c_code), (h_name, c_header)] = codegen( ... ("f", x+y*z), "C89", "test", header=False, empty=False) >>> print(c_name) test.c >>> print(c_code) #include "test.h" #include <math.h> double f(double x, double y, double z) { double f_result; f_result = x + y*z; return f_result; } <BLANKLINE> >>> print(h_name) test.h >>> print(c_header) #ifndef PROJECT__TEST__H #define PROJECT__TEST__H double f(double x, double y, double z); #endif <BLANKLINE> Another example using Equality objects to give named outputs. Here the filename (prefix) is taken from the first (name, expr) pair. >>> from sympy.abc import f, g >>> from sympy import Eq >>> [(c_name, c_code), (h_name, c_header)] = codegen( ... [("myfcn", x + y), ("fcn2", [Eq(f, 2*x), Eq(g, y)])], ... "C99", header=False, empty=False) >>> print(c_name) myfcn.c >>> print(c_code) #include "myfcn.h" #include <math.h> double myfcn(double x, double y) { double myfcn_result; myfcn_result = x + y; return myfcn_result; } void fcn2(double x, double y, double *f, double *g) { (*f) = 2*x; (*g) = y; } <BLANKLINE> If the generated function(s) will be part of a larger project where various global variables have been defined, the 'global_vars' option can be used to remove the specified variables from the function signature >>> from sympy.utilities.codegen import codegen >>> from sympy.abc import x, y, z >>> [(f_name, f_code), header] = codegen( ... ("f", x+y*z), "F95", header=False, empty=False, ... argument_sequence=(x, y), global_vars=(z,)) >>> print(f_code) REAL*8 function f(x, y) implicit none REAL*8, intent(in) :: x REAL*8, intent(in) :: y f = x + y*z end function <BLANKLINE> """ # Initialize the code generator. if language is None: if code_gen is None: raise ValueError("Need either language or code_gen") else: if code_gen is not None: raise ValueError("You cannot specify both language and code_gen.") code_gen = get_code_generator(language, project, standard, printer) if isinstance(name_expr[0], string_types): # single tuple is given, turn it into a singleton list with a tuple. name_expr = [name_expr] if prefix is None: prefix = name_expr[0][0] # Construct Routines appropriate for this code_gen from (name, expr) pairs. routines = [] for name, expr in name_expr: routines.append(code_gen.routine(name, expr, argument_sequence, global_vars)) # Write the code. return code_gen.write(routines, prefix, to_files, header, empty) def make_routine(name, expr, argument_sequence=None, global_vars=None, language="F95"): """A factory that makes an appropriate Routine from an expression. Parameters ========== name : string The name of this routine in the generated code. expr : expression or list/tuple of expressions A SymPy expression that the Routine instance will represent. If given a list or tuple of expressions, the routine will be considered to have multiple return values and/or output arguments. argument_sequence : list or tuple, optional List arguments for the routine in a preferred order. If omitted, the results are language dependent, for example, alphabetical order or in the same order as the given expressions. global_vars : iterable, optional Sequence of global variables used by the routine. Variables listed here will not show up as function arguments. language : string, optional Specify a target language. The Routine itself should be language-agnostic but the precise way one is created, error checking, etc depend on the language. [default: "F95"]. A decision about whether to use output arguments or return values is made depending on both the language and the particular mathematical expressions. For an expression of type Equality, the left hand side is typically made into an OutputArgument (or perhaps an InOutArgument if appropriate). Otherwise, typically, the calculated expression is made a return values of the routine. Examples ======== >>> from sympy.utilities.codegen import make_routine >>> from sympy.abc import x, y, f, g >>> from sympy import Eq >>> r = make_routine('test', [Eq(f, 2*x), Eq(g, x + y)]) >>> [arg.result_var for arg in r.results] [] >>> [arg.name for arg in r.arguments] [x, y, f, g] >>> [arg.name for arg in r.result_variables] [f, g] >>> r.local_vars set() Another more complicated example with a mixture of specified and automatically-assigned names. Also has Matrix output. >>> from sympy import Matrix >>> r = make_routine('fcn', [x*y, Eq(f, 1), Eq(g, x + g), Matrix([[x, 2]])]) >>> [arg.result_var for arg in r.results] # doctest: +SKIP [result_5397460570204848505] >>> [arg.expr for arg in r.results] [x*y] >>> [arg.name for arg in r.arguments] # doctest: +SKIP [x, y, f, g, out_8598435338387848786] We can examine the various arguments more closely: >>> from sympy.utilities.codegen import (InputArgument, OutputArgument, ... InOutArgument) >>> [a.name for a in r.arguments if isinstance(a, InputArgument)] [x, y] >>> [a.name for a in r.arguments if isinstance(a, OutputArgument)] # doctest: +SKIP [f, out_8598435338387848786] >>> [a.expr for a in r.arguments if isinstance(a, OutputArgument)] [1, Matrix([[x, 2]])] >>> [a.name for a in r.arguments if isinstance(a, InOutArgument)] [g] >>> [a.expr for a in r.arguments if isinstance(a, InOutArgument)] [g + x] """ # initialize a new code generator code_gen = get_code_generator(language) return code_gen.routine(name, expr, argument_sequence, global_vars)

ec0a315c77a569a13d0a7b0b877a989cc22eb594c8caf82173b78cc30cc23b20

"""Module for compiling codegen output, and wrap the binary for use in python. .. note:: To use the autowrap module it must first be imported >>> from sympy.utilities.autowrap import autowrap This module provides a common interface for different external backends, such as f2py, fwrap, Cython, SWIG(?) etc. (Currently only f2py and Cython are implemented) The goal is to provide access to compiled binaries of acceptable performance with a one-button user interface, i.e. >>> from sympy.abc import x,y >>> expr = ((x - y)**(25)).expand() >>> binary_callable = autowrap(expr) >>> binary_callable(1, 2) -1.0 The callable returned from autowrap() is a binary python function, not a SymPy object. If it is desired to use the compiled function in symbolic expressions, it is better to use binary_function() which returns a SymPy Function object. The binary callable is attached as the _imp_ attribute and invoked when a numerical evaluation is requested with evalf(), or with lambdify(). >>> from sympy.utilities.autowrap import binary_function >>> f = binary_function('f', expr) >>> 2*f(x, y) + y y + 2*f(x, y) >>> (2*f(x, y) + y).evalf(2, subs={x: 1, y:2}) 0.e-110 The idea is that a SymPy user will primarily be interested in working with mathematical expressions, and should not have to learn details about wrapping tools in order to evaluate expressions numerically, even if they are computationally expensive. When is this useful? 1) For computations on large arrays, Python iterations may be too slow, and depending on the mathematical expression, it may be difficult to exploit the advanced index operations provided by NumPy. 2) For *really* long expressions that will be called repeatedly, the compiled binary should be significantly faster than SymPy's .evalf() 3) If you are generating code with the codegen utility in order to use it in another project, the automatic python wrappers let you test the binaries immediately from within SymPy. 4) To create customized ufuncs for use with numpy arrays. See *ufuncify*. When is this module NOT the best approach? 1) If you are really concerned about speed or memory optimizations, you will probably get better results by working directly with the wrapper tools and the low level code. However, the files generated by this utility may provide a useful starting point and reference code. Temporary files will be left intact if you supply the keyword tempdir="path/to/files/". 2) If the array computation can be handled easily by numpy, and you don't need the binaries for another project. """ from __future__ import print_function, division import sys import os import shutil import tempfile from subprocess import STDOUT, CalledProcessError, check_output from string import Template from warnings import warn from sympy.core.cache import cacheit from sympy.core.compatibility import range, iterable from sympy.core.function import Lambda from sympy.core.relational import Eq from sympy.core.symbol import Dummy, Symbol from sympy.tensor.indexed import Idx, IndexedBase from sympy.utilities.codegen import (make_routine, get_code_generator, OutputArgument, InOutArgument, InputArgument, CodeGenArgumentListError, Result, ResultBase, C99CodeGen) from sympy.utilities.lambdify import implemented_function from sympy.utilities.decorator import doctest_depends_on _doctest_depends_on = {'exe': ('f2py', 'gfortran', 'gcc'), 'modules': ('numpy',)} class CodeWrapError(Exception): pass class CodeWrapper(object): """Base Class for code wrappers""" _filename = "wrapped_code" _module_basename = "wrapper_module" _module_counter = 0 @property def filename(self): return "%s_%s" % (self._filename, CodeWrapper._module_counter) @property def module_name(self): return "%s_%s" % (self._module_basename, CodeWrapper._module_counter) def __init__(self, generator, filepath=None, flags=[], verbose=False): """ generator -- the code generator to use """ self.generator = generator self.filepath = filepath self.flags = flags self.quiet = not verbose @property def include_header(self): return bool(self.filepath) @property def include_empty(self): return bool(self.filepath) def _generate_code(self, main_routine, routines): routines.append(main_routine) self.generator.write( routines, self.filename, True, self.include_header, self.include_empty) def wrap_code(self, routine, helpers=[]): if self.filepath: workdir = os.path.abspath(self.filepath) else: workdir = tempfile.mkdtemp("_sympy_compile") if not os.access(workdir, os.F_OK): os.mkdir(workdir) oldwork = os.getcwd() os.chdir(workdir) try: sys.path.append(workdir) self._generate_code(routine, helpers) self._prepare_files(routine) self._process_files(routine) mod = __import__(self.module_name) finally: sys.path.remove(workdir) CodeWrapper._module_counter += 1 os.chdir(oldwork) if not self.filepath: try: shutil.rmtree(workdir) except OSError: # Could be some issues on Windows pass return self._get_wrapped_function(mod, routine.name) def _process_files(self, routine): command = self.command command.extend(self.flags) try: retoutput = check_output(command, stderr=STDOUT) except CalledProcessError as e: raise CodeWrapError( "Error while executing command: %s. Command output is:\n%s" % ( " ".join(command), e.output.decode('utf-8'))) if not self.quiet: print(retoutput) class DummyWrapper(CodeWrapper): """Class used for testing independent of backends """ template = """# dummy module for testing of SymPy def %(name)s(): return "%(expr)s" %(name)s.args = "%(args)s" %(name)s.returns = "%(retvals)s" """ def _prepare_files(self, routine): return def _generate_code(self, routine, helpers): with open('%s.py' % self.module_name, 'w') as f: printed = ", ".join( [str(res.expr) for res in routine.result_variables]) # convert OutputArguments to return value like f2py args = filter(lambda x: not isinstance( x, OutputArgument), routine.arguments) retvals = [] for val in routine.result_variables: if isinstance(val, Result): retvals.append('nameless') else: retvals.append(val.result_var) print(DummyWrapper.template % { 'name': routine.name, 'expr': printed, 'args': ", ".join([str(a.name) for a in args]), 'retvals': ", ".join([str(val) for val in retvals]) }, end="", file=f) def _process_files(self, routine): return @classmethod def _get_wrapped_function(cls, mod, name): return getattr(mod, name) class CythonCodeWrapper(CodeWrapper): """Wrapper that uses Cython""" setup_template = """\ try: from setuptools import setup from setuptools import Extension except ImportError: from distutils.core import setup from distutils.extension import Extension from Cython.Build import cythonize cy_opts = {cythonize_options} {np_import} ext_mods = [Extension( {ext_args}, include_dirs={include_dirs}, library_dirs={library_dirs}, libraries={libraries}, extra_compile_args={extra_compile_args}, extra_link_args={extra_link_args} )] setup(ext_modules=cythonize(ext_mods, **cy_opts)) """ pyx_imports = ( "import numpy as np\n" "cimport numpy as np\n\n") pyx_header = ( "cdef extern from '{header_file}.h':\n" " {prototype}\n\n") pyx_func = ( "def {name}_c({arg_string}):\n" "\n" "{declarations}" "{body}") std_compile_flag = '-std=c99' def __init__(self, *args, **kwargs): """Instantiates a Cython code wrapper. The following optional parameters get passed to ``distutils.Extension`` for building the Python extension module. Read its documentation to learn more. Parameters ========== include_dirs : [list of strings] A list of directories to search for C/C++ header files (in Unix form for portability). library_dirs : [list of strings] A list of directories to search for C/C++ libraries at link time. libraries : [list of strings] A list of library names (not filenames or paths) to link against. extra_compile_args : [list of strings] Any extra platform- and compiler-specific information to use when compiling the source files in 'sources'. For platforms and compilers where "command line" makes sense, this is typically a list of command-line arguments, but for other platforms it could be anything. Note that the attribute ``std_compile_flag`` will be appended to this list. extra_link_args : [list of strings] Any extra platform- and compiler-specific information to use when linking object files together to create the extension (or to create a new static Python interpreter). Similar interpretation as for 'extra_compile_args'. cythonize_options : [dictionary] Keyword arguments passed on to cythonize. """ self._include_dirs = kwargs.pop('include_dirs', []) self._library_dirs = kwargs.pop('library_dirs', []) self._libraries = kwargs.pop('libraries', []) self._extra_compile_args = kwargs.pop('extra_compile_args', []) self._extra_compile_args.append(self.std_compile_flag) self._extra_link_args = kwargs.pop('extra_link_args', []) self._cythonize_options = kwargs.pop('cythonize_options', {}) self._need_numpy = False super(CythonCodeWrapper, self).__init__(*args, **kwargs) @property def command(self): command = [sys.executable, "setup.py", "build_ext", "--inplace"] return command def _prepare_files(self, routine, build_dir=os.curdir): # NOTE : build_dir is used for testing purposes. pyxfilename = self.module_name + '.pyx' codefilename = "%s.%s" % (self.filename, self.generator.code_extension) # pyx with open(os.path.join(build_dir, pyxfilename), 'w') as f: self.dump_pyx([routine], f, self.filename) # setup.py ext_args = [repr(self.module_name), repr([pyxfilename, codefilename])] if self._need_numpy: np_import = 'import numpy as np\n' self._include_dirs.append('np.get_include()') else: np_import = '' with open(os.path.join(build_dir, 'setup.py'), 'w') as f: includes = str(self._include_dirs).replace("'np.get_include()'", 'np.get_include()') f.write(self.setup_template.format( ext_args=", ".join(ext_args), np_import=np_import, include_dirs=includes, library_dirs=self._library_dirs, libraries=self._libraries, extra_compile_args=self._extra_compile_args, extra_link_args=self._extra_link_args, cythonize_options=self._cythonize_options )) @classmethod def _get_wrapped_function(cls, mod, name): return getattr(mod, name + '_c') def dump_pyx(self, routines, f, prefix): """Write a Cython file with python wrappers This file contains all the definitions of the routines in c code and refers to the header file. Arguments --------- routines List of Routine instances f File-like object to write the file to prefix The filename prefix, used to refer to the proper header file. Only the basename of the prefix is used. """ headers = [] functions = [] for routine in routines: prototype = self.generator.get_prototype(routine) # C Function Header Import headers.append(self.pyx_header.format(header_file=prefix, prototype=prototype)) # Partition the C function arguments into categories py_rets, py_args, py_loc, py_inf = self._partition_args(routine.arguments) # Function prototype name = routine.name arg_string = ", ".join(self._prototype_arg(arg) for arg in py_args) # Local Declarations local_decs = [] for arg, val in py_inf.items(): proto = self._prototype_arg(arg) mat, ind = val local_decs.append(" cdef {0} = {1}.shape[{2}]".format(proto, mat, ind)) local_decs.extend([" cdef {0}".format(self._declare_arg(a)) for a in py_loc]) declarations = "\n".join(local_decs) if declarations: declarations = declarations + "\n" # Function Body args_c = ", ".join([self._call_arg(a) for a in routine.arguments]) rets = ", ".join([str(r.name) for r in py_rets]) if routine.results: body = ' return %s(%s)' % (routine.name, args_c) if rets: body = body + ', ' + rets else: body = ' %s(%s)\n' % (routine.name, args_c) body = body + ' return ' + rets functions.append(self.pyx_func.format(name=name, arg_string=arg_string, declarations=declarations, body=body)) # Write text to file if self._need_numpy: # Only import numpy if required f.write(self.pyx_imports) f.write('\n'.join(headers)) f.write('\n'.join(functions)) def _partition_args(self, args): """Group function arguments into categories.""" py_args = [] py_returns = [] py_locals = [] py_inferred = {} for arg in args: if isinstance(arg, OutputArgument): py_returns.append(arg) py_locals.append(arg) elif isinstance(arg, InOutArgument): py_returns.append(arg) py_args.append(arg) else: py_args.append(arg) # Find arguments that are array dimensions. These can be inferred # locally in the Cython code. if isinstance(arg, (InputArgument, InOutArgument)) and arg.dimensions: dims = [d[1] + 1 for d in arg.dimensions] sym_dims = [(i, d) for (i, d) in enumerate(dims) if isinstance(d, Symbol)] for (i, d) in sym_dims: py_inferred[d] = (arg.name, i) for arg in args: if arg.name in py_inferred: py_inferred[arg] = py_inferred.pop(arg.name) # Filter inferred arguments from py_args py_args = [a for a in py_args if a not in py_inferred] return py_returns, py_args, py_locals, py_inferred def _prototype_arg(self, arg): mat_dec = "np.ndarray[{mtype}, ndim={ndim}] {name}" np_types = {'double': 'np.double_t', 'int': 'np.int_t'} t = arg.get_datatype('c') if arg.dimensions: self._need_numpy = True ndim = len(arg.dimensions) mtype = np_types[t] return mat_dec.format(mtype=mtype, ndim=ndim, name=arg.name) else: return "%s %s" % (t, str(arg.name)) def _declare_arg(self, arg): proto = self._prototype_arg(arg) if arg.dimensions: shape = '(' + ','.join(str(i[1] + 1) for i in arg.dimensions) + ')' return proto + " = np.empty({shape})".format(shape=shape) else: return proto + " = 0" def _call_arg(self, arg): if arg.dimensions: t = arg.get_datatype('c') return "<{0}*> {1}.data".format(t, arg.name) elif isinstance(arg, ResultBase): return "&{0}".format(arg.name) else: return str(arg.name) class F2PyCodeWrapper(CodeWrapper): """Wrapper that uses f2py""" def __init__(self, *args, **kwargs): ext_keys = ['include_dirs', 'library_dirs', 'libraries', 'extra_compile_args', 'extra_link_args'] msg = ('The compilation option kwarg {} is not supported with the f2py ' 'backend.') for k in ext_keys: if k in kwargs.keys(): warn(msg.format(k)) kwargs.pop(k, None) super(F2PyCodeWrapper, self).__init__(*args, **kwargs) @property def command(self): filename = self.filename + '.' + self.generator.code_extension args = ['-c', '-m', self.module_name, filename] command = [sys.executable, "-c", "import numpy.f2py as f2py2e;f2py2e.main()"]+args return command def _prepare_files(self, routine): pass @classmethod def _get_wrapped_function(cls, mod, name): return getattr(mod, name) # Here we define a lookup of backends -> tuples of languages. For now, each # tuple is of length 1, but if a backend supports more than one language, # the most preferable language is listed first. _lang_lookup = {'CYTHON': ('C99', 'C89', 'C'), 'F2PY': ('F95',), 'NUMPY': ('C99', 'C89', 'C'), 'DUMMY': ('F95',)} # Dummy here just for testing def _infer_language(backend): """For a given backend, return the top choice of language""" langs = _lang_lookup.get(backend.upper(), False) if not langs: raise ValueError("Unrecognized backend: " + backend) return langs[0] def _validate_backend_language(backend, language): """Throws error if backend and language are incompatible""" langs = _lang_lookup.get(backend.upper(), False) if not langs: raise ValueError("Unrecognized backend: " + backend) if language.upper() not in langs: raise ValueError(("Backend {0} and language {1} are " "incompatible").format(backend, language)) @cacheit @doctest_depends_on(exe=('f2py', 'gfortran'), modules=('numpy',)) def autowrap(expr, language=None, backend='f2py', tempdir=None, args=None, flags=None, verbose=False, helpers=None, code_gen=None, **kwargs): """Generates python callable binaries based on the math expression. Parameters ========== expr The SymPy expression that should be wrapped as a binary routine. language : string, optional If supplied, (options: 'C' or 'F95'), specifies the language of the generated code. If ``None`` [default], the language is inferred based upon the specified backend. backend : string, optional Backend used to wrap the generated code. Either 'f2py' [default], or 'cython'. tempdir : string, optional Path to directory for temporary files. If this argument is supplied, the generated code and the wrapper input files are left intact in the specified path. args : iterable, optional An ordered iterable of symbols. Specifies the argument sequence for the function. flags : iterable, optional Additional option flags that will be passed to the backend. verbose : bool, optional If True, autowrap will not mute the command line backends. This can be helpful for debugging. helpers : 3-tuple or iterable of 3-tuples, optional Used to define auxiliary expressions needed for the main expr. If the main expression needs to call a specialized function it should be passed in via ``helpers``. Autowrap will then make sure that the compiled main expression can link to the helper routine. Items should be 3-tuples with (<function_name>, <sympy_expression>, <argument_tuple>). It is mandatory to supply an argument sequence to helper routines. code_gen : CodeGen instance An instance of a CodeGen subclass. Overrides ``language``. include_dirs : [string] A list of directories to search for C/C++ header files (in Unix form for portability). library_dirs : [string] A list of directories to search for C/C++ libraries at link time. libraries : [string] A list of library names (not filenames or paths) to link against. extra_compile_args : [string] Any extra platform- and compiler-specific information to use when compiling the source files in 'sources'. For platforms and compilers where "command line" makes sense, this is typically a list of command-line arguments, but for other platforms it could be anything. extra_link_args : [string] Any extra platform- and compiler-specific information to use when linking object files together to create the extension (or to create a new static Python interpreter). Similar interpretation as for 'extra_compile_args'. Examples ======== >>> from sympy.abc import x, y, z >>> from sympy.utilities.autowrap import autowrap >>> expr = ((x - y + z)**(13)).expand() >>> binary_func = autowrap(expr) >>> binary_func(1, 4, 2) -1.0 """ if language: if not isinstance(language, type): _validate_backend_language(backend, language) else: language = _infer_language(backend) # two cases 1) helpers is an iterable of 3-tuples and 2) helpers is a # 3-tuple if iterable(helpers) and len(helpers) != 0 and iterable(helpers[0]): helpers = helpers if helpers else () else: helpers = [helpers] if helpers else () args = list(args) if iterable(args, exclude=set) else args if code_gen is None: code_gen = get_code_generator(language, "autowrap") CodeWrapperClass = { 'F2PY': F2PyCodeWrapper, 'CYTHON': CythonCodeWrapper, 'DUMMY': DummyWrapper }[backend.upper()] code_wrapper = CodeWrapperClass(code_gen, tempdir, flags if flags else (), verbose, **kwargs) helps = [] for name_h, expr_h, args_h in helpers: helps.append(code_gen.routine(name_h, expr_h, args_h)) for name_h, expr_h, args_h in helpers: if expr.has(expr_h): name_h = binary_function(name_h, expr_h, backend='dummy') expr = expr.subs(expr_h, name_h(*args_h)) try: routine = code_gen.routine('autofunc', expr, args) except CodeGenArgumentListError as e: # if all missing arguments are for pure output, we simply attach them # at the end and try again, because the wrappers will silently convert # them to return values anyway. new_args = [] for missing in e.missing_args: if not isinstance(missing, OutputArgument): raise new_args.append(missing.name) routine = code_gen.routine('autofunc', expr, args + new_args) return code_wrapper.wrap_code(routine, helpers=helps) @doctest_depends_on(exe=('f2py', 'gfortran'), modules=('numpy',)) def binary_function(symfunc, expr, **kwargs): """Returns a sympy function with expr as binary implementation This is a convenience function that automates the steps needed to autowrap the SymPy expression and attaching it to a Function object with implemented_function(). Parameters ========== symfunc : sympy Function The function to bind the callable to. expr : sympy Expression The expression used to generate the function. kwargs : dict Any kwargs accepted by autowrap. Examples ======== >>> from sympy.abc import x, y >>> from sympy.utilities.autowrap import binary_function >>> expr = ((x - y)**(25)).expand() >>> f = binary_function('f', expr) >>> type(f) <class 'sympy.core.function.UndefinedFunction'> >>> 2*f(x, y) 2*f(x, y) >>> f(x, y).evalf(2, subs={x: 1, y: 2}) -1.0 """ binary = autowrap(expr, **kwargs) return implemented_function(symfunc, binary) ################################################################# # UFUNCIFY # ################################################################# _ufunc_top = Template("""\ #include "Python.h" #include "math.h" #include "numpy/ndarraytypes.h" #include "numpy/ufuncobject.h" #include "numpy/halffloat.h" #include ${include_file} static PyMethodDef ${module}Methods[] = { {NULL, NULL, 0, NULL} };""") _ufunc_outcalls = Template("*((double *)out${outnum}) = ${funcname}(${call_args});") _ufunc_body = Template("""\ static void ${funcname}_ufunc(char **args, npy_intp *dimensions, npy_intp* steps, void* data) { npy_intp i; npy_intp n = dimensions[0]; ${declare_args} ${declare_steps} for (i = 0; i < n; i++) { ${outcalls} ${step_increments} } } PyUFuncGenericFunction ${funcname}_funcs[1] = {&${funcname}_ufunc}; static char ${funcname}_types[${n_types}] = ${types} static void *${funcname}_data[1] = {NULL};""") _ufunc_bottom = Template("""\ #if PY_VERSION_HEX >= 0x03000000 static struct PyModuleDef moduledef = { PyModuleDef_HEAD_INIT, "${module}", NULL, -1, ${module}Methods, NULL, NULL, NULL, NULL }; PyMODINIT_FUNC PyInit_${module}(void) { PyObject *m, *d; ${function_creation} m = PyModule_Create(&moduledef); if (!m) { return NULL; } import_array(); import_umath(); d = PyModule_GetDict(m); ${ufunc_init} return m; } #else PyMODINIT_FUNC init${module}(void) { PyObject *m, *d; ${function_creation} m = Py_InitModule("${module}", ${module}Methods); if (m == NULL) { return; } import_array(); import_umath(); d = PyModule_GetDict(m); ${ufunc_init} } #endif\ """) _ufunc_init_form = Template("""\ ufunc${ind} = PyUFunc_FromFuncAndData(${funcname}_funcs, ${funcname}_data, ${funcname}_types, 1, ${n_in}, ${n_out}, PyUFunc_None, "${module}", ${docstring}, 0); PyDict_SetItemString(d, "${funcname}", ufunc${ind}); Py_DECREF(ufunc${ind});""") _ufunc_setup = Template("""\ def configuration(parent_package='', top_path=None): import numpy from numpy.distutils.misc_util import Configuration config = Configuration('', parent_package, top_path) config.add_extension('${module}', sources=['${module}.c', '${filename}.c']) return config if __name__ == "__main__": from numpy.distutils.core import setup setup(configuration=configuration)""") class UfuncifyCodeWrapper(CodeWrapper): """Wrapper for Ufuncify""" def __init__(self, *args, **kwargs): ext_keys = ['include_dirs', 'library_dirs', 'libraries', 'extra_compile_args', 'extra_link_args'] msg = ('The compilation option kwarg {} is not supported with the numpy' ' backend.') for k in ext_keys: if k in kwargs.keys(): warn(msg.format(k)) kwargs.pop(k, None) super(UfuncifyCodeWrapper, self).__init__(*args, **kwargs) @property def command(self): command = [sys.executable, "setup.py", "build_ext", "--inplace"] return command def wrap_code(self, routines, helpers=None): # This routine overrides CodeWrapper because we can't assume funcname == routines[0].name # Therefore we have to break the CodeWrapper private API. # There isn't an obvious way to extend multi-expr support to # the other autowrap backends, so we limit this change to ufuncify. helpers = helpers if helpers is not None else [] # We just need a consistent name funcname = 'wrapped_' + str(id(routines) + id(helpers)) workdir = self.filepath or tempfile.mkdtemp("_sympy_compile") if not os.access(workdir, os.F_OK): os.mkdir(workdir) oldwork = os.getcwd() os.chdir(workdir) try: sys.path.append(workdir) self._generate_code(routines, helpers) self._prepare_files(routines, funcname) self._process_files(routines) mod = __import__(self.module_name) finally: sys.path.remove(workdir) CodeWrapper._module_counter += 1 os.chdir(oldwork) if not self.filepath: try: shutil.rmtree(workdir) except OSError: # Could be some issues on Windows pass return self._get_wrapped_function(mod, funcname) def _generate_code(self, main_routines, helper_routines): all_routines = main_routines + helper_routines self.generator.write( all_routines, self.filename, True, self.include_header, self.include_empty) def _prepare_files(self, routines, funcname): # C codefilename = self.module_name + '.c' with open(codefilename, 'w') as f: self.dump_c(routines, f, self.filename, funcname=funcname) # setup.py with open('setup.py', 'w') as f: self.dump_setup(f) @classmethod def _get_wrapped_function(cls, mod, name): return getattr(mod, name) def dump_setup(self, f): setup = _ufunc_setup.substitute(module=self.module_name, filename=self.filename) f.write(setup) def dump_c(self, routines, f, prefix, funcname=None): """Write a C file with python wrappers This file contains all the definitions of the routines in c code. Arguments --------- routines List of Routine instances f File-like object to write the file to prefix The filename prefix, used to name the imported module. funcname Name of the main function to be returned. """ if (funcname is None) and (len(routines) == 1): funcname = routines[0].name elif funcname is None: msg = 'funcname must be specified for multiple output routines' raise ValueError(msg) functions = [] function_creation = [] ufunc_init = [] module = self.module_name include_file = "\"{0}.h\"".format(prefix) top = _ufunc_top.substitute(include_file=include_file, module=module) name = funcname # Partition the C function arguments into categories # Here we assume all routines accept the same arguments r_index = 0 py_in, _ = self._partition_args(routines[0].arguments) n_in = len(py_in) n_out = len(routines) # Declare Args form = "char *{0}{1} = args[{2}];" arg_decs = [form.format('in', i, i) for i in range(n_in)] arg_decs.extend([form.format('out', i, i+n_in) for i in range(n_out)]) declare_args = '\n '.join(arg_decs) # Declare Steps form = "npy_intp {0}{1}_step = steps[{2}];" step_decs = [form.format('in', i, i) for i in range(n_in)] step_decs.extend([form.format('out', i, i+n_in) for i in range(n_out)]) declare_steps = '\n '.join(step_decs) # Call Args form = "*(double *)in{0}" call_args = ', '.join([form.format(a) for a in range(n_in)]) # Step Increments form = "{0}{1} += {0}{1}_step;" step_incs = [form.format('in', i) for i in range(n_in)] step_incs.extend([form.format('out', i, i) for i in range(n_out)]) step_increments = '\n '.join(step_incs) # Types n_types = n_in + n_out types = "{" + ', '.join(["NPY_DOUBLE"]*n_types) + "};" # Docstring docstring = '"Created in SymPy with Ufuncify"' # Function Creation function_creation.append("PyObject *ufunc{0};".format(r_index)) # Ufunc initialization init_form = _ufunc_init_form.substitute(module=module, funcname=name, docstring=docstring, n_in=n_in, n_out=n_out, ind=r_index) ufunc_init.append(init_form) outcalls = [_ufunc_outcalls.substitute( outnum=i, call_args=call_args, funcname=routines[i].name) for i in range(n_out)] body = _ufunc_body.substitute(module=module, funcname=name, declare_args=declare_args, declare_steps=declare_steps, call_args=call_args, step_increments=step_increments, n_types=n_types, types=types, outcalls='\n '.join(outcalls)) functions.append(body) body = '\n\n'.join(functions) ufunc_init = '\n '.join(ufunc_init) function_creation = '\n '.join(function_creation) bottom = _ufunc_bottom.substitute(module=module, ufunc_init=ufunc_init, function_creation=function_creation) text = [top, body, bottom] f.write('\n\n'.join(text)) def _partition_args(self, args): """Group function arguments into categories.""" py_in = [] py_out = [] for arg in args: if isinstance(arg, OutputArgument): py_out.append(arg) elif isinstance(arg, InOutArgument): raise ValueError("Ufuncify doesn't support InOutArguments") else: py_in.append(arg) return py_in, py_out @cacheit @doctest_depends_on(exe=('f2py', 'gfortran', 'gcc'), modules=('numpy',)) def ufuncify(args, expr, language=None, backend='numpy', tempdir=None, flags=None, verbose=False, helpers=None, **kwargs): """Generates a binary function that supports broadcasting on numpy arrays. Parameters ========== args : iterable Either a Symbol or an iterable of symbols. Specifies the argument sequence for the function. expr A SymPy expression that defines the element wise operation. language : string, optional If supplied, (options: 'C' or 'F95'), specifies the language of the generated code. If ``None`` [default], the language is inferred based upon the specified backend. backend : string, optional Backend used to wrap the generated code. Either 'numpy' [default], 'cython', or 'f2py'. tempdir : string, optional Path to directory for temporary files. If this argument is supplied, the generated code and the wrapper input files are left intact in the specified path. flags : iterable, optional Additional option flags that will be passed to the backend. verbose : bool, optional If True, autowrap will not mute the command line backends. This can be helpful for debugging. helpers : iterable, optional Used to define auxiliary expressions needed for the main expr. If the main expression needs to call a specialized function it should be put in the ``helpers`` iterable. Autowrap will then make sure that the compiled main expression can link to the helper routine. Items should be tuples with (<funtion_name>, <sympy_expression>, <arguments>). It is mandatory to supply an argument sequence to helper routines. kwargs : dict These kwargs will be passed to autowrap if the `f2py` or `cython` backend is used and ignored if the `numpy` backend is used. Notes ===== The default backend ('numpy') will create actual instances of ``numpy.ufunc``. These support ndimensional broadcasting, and implicit type conversion. Use of the other backends will result in a "ufunc-like" function, which requires equal length 1-dimensional arrays for all arguments, and will not perform any type conversions. References ========== .. [1] http://docs.scipy.org/doc/numpy/reference/ufuncs.html Examples ======== >>> from sympy.utilities.autowrap import ufuncify >>> from sympy.abc import x, y >>> import numpy as np >>> f = ufuncify((x, y), y + x**2) >>> type(f) <class 'numpy.ufunc'> >>> f([1, 2, 3], 2) array([ 3., 6., 11.]) >>> f(np.arange(5), 3) array([ 3., 4., 7., 12., 19.]) For the 'f2py' and 'cython' backends, inputs are required to be equal length 1-dimensional arrays. The 'f2py' backend will perform type conversion, but the Cython backend will error if the inputs are not of the expected type. >>> f_fortran = ufuncify((x, y), y + x**2, backend='f2py') >>> f_fortran(1, 2) array([ 3.]) >>> f_fortran(np.array([1, 2, 3]), np.array([1.0, 2.0, 3.0])) array([ 2., 6., 12.]) >>> f_cython = ufuncify((x, y), y + x**2, backend='Cython') >>> f_cython(1, 2) # doctest: +ELLIPSIS Traceback (most recent call last): ... TypeError: Argument '_x' has incorrect type (expected numpy.ndarray, got int) >>> f_cython(np.array([1.0]), np.array([2.0])) array([ 3.]) """ if isinstance(args, Symbol): args = (args,) else: args = tuple(args) if language: _validate_backend_language(backend, language) else: language = _infer_language(backend) helpers = helpers if helpers else () flags = flags if flags else () if backend.upper() == 'NUMPY': # maxargs is set by numpy compile-time constant NPY_MAXARGS # If a future version of numpy modifies or removes this restriction # this variable should be changed or removed maxargs = 32 helps = [] for name, expr, args in helpers: helps.append(make_routine(name, expr, args)) code_wrapper = UfuncifyCodeWrapper(C99CodeGen("ufuncify"), tempdir, flags, verbose) if not isinstance(expr, (list, tuple)): expr = [expr] if len(expr) == 0: raise ValueError('Expression iterable has zero length') if (len(expr) + len(args)) > maxargs: msg = ('Cannot create ufunc with more than {0} total arguments: ' 'got {1} in, {2} out') raise ValueError(msg.format(maxargs, len(args), len(expr))) routines = [make_routine('autofunc{}'.format(idx), exprx, args) for idx, exprx in enumerate(expr)] return code_wrapper.wrap_code(routines, helpers=helps) else: # Dummies are used for all added expressions to prevent name clashes # within the original expression. y = IndexedBase(Dummy('y')) m = Dummy('m', integer=True) i = Idx(Dummy('i', integer=True), m) f_dummy = Dummy('f') f = implemented_function('%s_%d' % (f_dummy.name, f_dummy.dummy_index), Lambda(args, expr)) # For each of the args create an indexed version. indexed_args = [IndexedBase(Dummy(str(a))) for a in args] # Order the arguments (out, args, dim) args = [y] + indexed_args + [m] args_with_indices = [a[i] for a in indexed_args] return autowrap(Eq(y[i], f(*args_with_indices)), language, backend, tempdir, args, flags, verbose, helpers, **kwargs)

42c1a320f4d2ffeaa8947177b760507f513fa84a723043ce82f55474c9d5095a

""" This module adds several functions for interactive source code inspection. """ from __future__ import print_function, division from sympy.core.decorators import deprecated import inspect @deprecated(useinstead="?? in IPython/Jupyter or inspect.getsource", issue=14905, deprecated_since_version="1.3") def source(object): """ Prints the source code of a given object. """ print('In file: %s' % inspect.getsourcefile(object)) print(inspect.getsource(object)) def get_class(lookup_view): """ Convert a string version of a class name to the object. For example, get_class('sympy.core.Basic') will return class Basic located in module sympy.core """ if isinstance(lookup_view, str): mod_name, func_name = get_mod_func(lookup_view) if func_name != '': lookup_view = getattr( __import__(mod_name, {}, {}, ['*']), func_name) if not callable(lookup_view): raise AttributeError( "'%s.%s' is not a callable." % (mod_name, func_name)) return lookup_view def get_mod_func(callback): """ splits the string path to a class into a string path to the module and the name of the class. Examples ======== >>> from sympy.utilities.source import get_mod_func >>> get_mod_func('sympy.core.basic.Basic') ('sympy.core.basic', 'Basic') """ dot = callback.rfind('.') if dot == -1: return callback, '' return callback[:dot], callback[dot + 1:]

55b765a419a55133582cbc376e8c79ab512cf9e475b6b99773ff763d02d94164

""" This module provides convenient functions to transform sympy expressions to lambda functions which can be used to calculate numerical values very fast. """ from __future__ import print_function, division import inspect import keyword import re import textwrap import linecache from sympy.core.compatibility import (exec_, is_sequence, iterable, NotIterable, string_types, range, builtins, PY3) from sympy.utilities.decorator import doctest_depends_on __doctest_requires__ = {('lambdify',): ['numpy', 'tensorflow']} # Default namespaces, letting us define translations that can't be defined # by simple variable maps, like I => 1j MATH_DEFAULT = {} MPMATH_DEFAULT = {} NUMPY_DEFAULT = {"I": 1j} SCIPY_DEFAULT = {"I": 1j} TENSORFLOW_DEFAULT = {} SYMPY_DEFAULT = {} NUMEXPR_DEFAULT = {} # These are the namespaces the lambda functions will use. # These are separate from the names above because they are modified # throughout this file, whereas the defaults should remain unmodified. MATH = MATH_DEFAULT.copy() MPMATH = MPMATH_DEFAULT.copy() NUMPY = NUMPY_DEFAULT.copy() SCIPY = SCIPY_DEFAULT.copy() TENSORFLOW = TENSORFLOW_DEFAULT.copy() SYMPY = SYMPY_DEFAULT.copy() NUMEXPR = NUMEXPR_DEFAULT.copy() # Mappings between sympy and other modules function names. MATH_TRANSLATIONS = { "ceiling": "ceil", "E": "e", "ln": "log", } MPMATH_TRANSLATIONS = { "Abs": "fabs", "elliptic_k": "ellipk", "elliptic_f": "ellipf", "elliptic_e": "ellipe", "elliptic_pi": "ellippi", "ceiling": "ceil", "chebyshevt": "chebyt", "chebyshevu": "chebyu", "E": "e", "I": "j", "ln": "log", #"lowergamma":"lower_gamma", "oo": "inf", #"uppergamma":"upper_gamma", "LambertW": "lambertw", "MutableDenseMatrix": "matrix", "ImmutableDenseMatrix": "matrix", "conjugate": "conj", "dirichlet_eta": "altzeta", "Ei": "ei", "Shi": "shi", "Chi": "chi", "Si": "si", "Ci": "ci", "RisingFactorial": "rf", "FallingFactorial": "ff", } NUMPY_TRANSLATIONS = {} SCIPY_TRANSLATIONS = {} TENSORFLOW_TRANSLATIONS = { "Abs": "abs", "ceiling": "ceil", "im": "imag", "ln": "log", "Mod": "mod", "conjugate": "conj", "re": "real", } NUMEXPR_TRANSLATIONS = {} # Available modules: MODULES = { "math": (MATH, MATH_DEFAULT, MATH_TRANSLATIONS, ("from math import *",)), "mpmath": (MPMATH, MPMATH_DEFAULT, MPMATH_TRANSLATIONS, ("from mpmath import *",)), "numpy": (NUMPY, NUMPY_DEFAULT, NUMPY_TRANSLATIONS, ("import numpy; from numpy import *; from numpy.linalg import *",)), "scipy": (SCIPY, SCIPY_DEFAULT, SCIPY_TRANSLATIONS, ("import numpy; import scipy; from scipy import *; from scipy.special import *",)), "tensorflow": (TENSORFLOW, TENSORFLOW_DEFAULT, TENSORFLOW_TRANSLATIONS, ("import_module('tensorflow')",)), "sympy": (SYMPY, SYMPY_DEFAULT, {}, ( "from sympy.functions import *", "from sympy.matrices import *", "from sympy import Integral, pi, oo, nan, zoo, E, I",)), "numexpr" : (NUMEXPR, NUMEXPR_DEFAULT, NUMEXPR_TRANSLATIONS, ("import_module('numexpr')", )), } def _import(module, reload=False): """ Creates a global translation dictionary for module. The argument module has to be one of the following strings: "math", "mpmath", "numpy", "sympy", "tensorflow". These dictionaries map names of python functions to their equivalent in other modules. """ # Required despite static analysis claiming it is not used from sympy.external import import_module try: namespace, namespace_default, translations, import_commands = MODULES[ module] except KeyError: raise NameError( "'%s' module can't be used for lambdification" % module) # Clear namespace or exit if namespace != namespace_default: # The namespace was already generated, don't do it again if not forced. if reload: namespace.clear() namespace.update(namespace_default) else: return for import_command in import_commands: if import_command.startswith('import_module'): module = eval(import_command) if module is not None: namespace.update(module.__dict__) continue else: try: exec_(import_command, {}, namespace) continue except ImportError: pass raise ImportError( "can't import '%s' with '%s' command" % (module, import_command)) # Add translated names to namespace for sympyname, translation in translations.items(): namespace[sympyname] = namespace[translation] # For computing the modulus of a sympy expression we use the builtin abs # function, instead of the previously used fabs function for all # translation modules. This is because the fabs function in the math # module does not accept complex valued arguments. (see issue 9474). The # only exception, where we don't use the builtin abs function is the # mpmath translation module, because mpmath.fabs returns mpf objects in # contrast to abs(). if 'Abs' not in namespace: namespace['Abs'] = abs # Used for dynamically generated filenames that are inserted into the # linecache. _lambdify_generated_counter = 1 @doctest_depends_on(modules=('numpy')) def lambdify(args, expr, modules=None, printer=None, use_imps=True, dummify=False): """ Returns an anonymous function for fast calculation of numerical values. If not specified differently by the user, ``modules`` defaults to ``["scipy", "numpy"]`` if SciPy is installed, ``["numpy"]`` if only NumPy is installed, and ``["math", "mpmath", "sympy"]`` if neither is installed. That is, SymPy functions are replaced as far as possible by either ``scipy`` or ``numpy`` functions if available, and Python's standard library ``math``, or ``mpmath`` functions otherwise. To change this behavior, the "modules" argument can be used. It accepts: - the strings "math", "mpmath", "numpy", "numexpr", "scipy", "sympy", "tensorflow" - any modules (e.g. math) - dictionaries that map names of sympy functions to arbitrary functions - lists that contain a mix of the arguments above, with higher priority given to entries appearing first. .. warning:: Note that this function uses ``eval``, and thus shouldn't be used on unsanitized input. Arguments in the provided expression that are not valid Python identifiers are substitued with dummy symbols. This allows for applied functions (e.g. f(t)) to be supplied as arguments. Call the function with dummify=True to replace all arguments with dummy symbols (if `args` is not a string) - for example, to ensure that the arguments do not redefine any built-in names. For functions involving large array calculations, numexpr can provide a significant speedup over numpy. Please note that the available functions for numexpr are more limited than numpy but can be expanded with implemented_function and user defined subclasses of Function. If specified, numexpr may be the only option in modules. The official list of numexpr functions can be found at: https://github.com/pydata/numexpr#supported-functions In previous releases ``lambdify`` replaced ``Matrix`` with ``numpy.matrix`` by default. As of release 1.0 ``numpy.array`` is the default. To get the old default behavior you must pass in ``[{'ImmutableDenseMatrix': numpy.matrix}, 'numpy']`` to the ``modules`` kwarg. >>> from sympy import lambdify, Matrix >>> from sympy.abc import x, y >>> import numpy >>> array2mat = [{'ImmutableDenseMatrix': numpy.matrix}, 'numpy'] >>> f = lambdify((x, y), Matrix([x, y]), modules=array2mat) >>> f(1, 2) [[1] [2]] Usage ===== (1) Use one of the provided modules: >>> from sympy import sin, tan, gamma >>> from sympy.abc import x, y >>> f = lambdify(x, sin(x), "math") Attention: Functions that are not in the math module will throw a name error when the function definition is evaluated! So this would be better: >>> f = lambdify(x, sin(x)*gamma(x), ("math", "mpmath", "sympy")) (2) Use some other module: >>> import numpy >>> f = lambdify((x,y), tan(x*y), numpy) Attention: There are naming differences between numpy and sympy. So if you simply take the numpy module, e.g. sympy.atan will not be translated to numpy.arctan. Use the modified module instead by passing the string "numpy": >>> f = lambdify((x,y), tan(x*y), "numpy") >>> f(1, 2) -2.18503986326 >>> from numpy import array >>> f(array([1, 2, 3]), array([2, 3, 5])) [-2.18503986 -0.29100619 -0.8559934 ] In the above examples, the generated functions can accept scalar values or numpy arrays as arguments. However, in some cases the generated function relies on the input being a numpy array: >>> from sympy import Piecewise >>> from sympy.utilities.pytest import ignore_warnings >>> f = lambdify(x, Piecewise((x, x <= 1), (1/x, x > 1)), "numpy") >>> with ignore_warnings(RuntimeWarning): ... f(array([-1, 0, 1, 2])) [-1. 0. 1. 0.5] >>> f(0) Traceback (most recent call last): ... ZeroDivisionError: division by zero In such cases, the input should be wrapped in a numpy array: >>> with ignore_warnings(RuntimeWarning): ... float(f(array([0]))) 0.0 Or if numpy functionality is not required another module can be used: >>> f = lambdify(x, Piecewise((x, x <= 1), (1/x, x > 1)), "math") >>> f(0) 0 (3) Use a dictionary defining custom functions: >>> def my_cool_function(x): return 'sin(%s) is cool' % x >>> myfuncs = {"sin" : my_cool_function} >>> f = lambdify(x, sin(x), myfuncs); f(1) 'sin(1) is cool' Examples ======== >>> from sympy.utilities.lambdify import implemented_function >>> from sympy import sqrt, sin, Matrix >>> from sympy import Function >>> from sympy.abc import w, x, y, z >>> f = lambdify(x, x**2) >>> f(2) 4 >>> f = lambdify((x, y, z), [z, y, x]) >>> f(1,2,3) [3, 2, 1] >>> f = lambdify(x, sqrt(x)) >>> f(4) 2.0 >>> f = lambdify((x, y), sin(x*y)**2) >>> f(0, 5) 0.0 >>> row = lambdify((x, y), Matrix((x, x + y)).T, modules='sympy') >>> row(1, 2) Matrix([[1, 3]]) Tuple arguments are handled and the lambdified function should be called with the same type of arguments as were used to create the function.: >>> f = lambdify((x, (y, z)), x + y) >>> f(1, (2, 4)) 3 A more robust way of handling this is to always work with flattened arguments: >>> from sympy.utilities.iterables import flatten >>> args = w, (x, (y, z)) >>> vals = 1, (2, (3, 4)) >>> f = lambdify(flatten(args), w + x + y + z) >>> f(*flatten(vals)) 10 Functions present in `expr` can also carry their own numerical implementations, in a callable attached to the ``_imp_`` attribute. Usually you attach this using the ``implemented_function`` factory: >>> f = implemented_function(Function('f'), lambda x: x+1) >>> func = lambdify(x, f(x)) >>> func(4) 5 ``lambdify`` always prefers ``_imp_`` implementations to implementations in other namespaces, unless the ``use_imps`` input parameter is False. Usage with Tensorflow module: >>> import tensorflow as tf >>> f = Max(x, sin(x)) >>> func = lambdify(x, f, 'tensorflow') >>> result = func(tf.constant(1.0)) >>> result # a tf.Tensor representing the result of the calculation <tf.Tensor 'Maximum:0' shape=() dtype=float32> >>> sess = tf.Session() >>> sess.run(result) # compute result 1.0 >>> var = tf.Variable(1.0) >>> sess.run(tf.global_variables_initializer()) >>> sess.run(func(var)) # also works for tf.Variable and tf.Placeholder 1.0 >>> tensor = tf.constant([[1.0, 2.0], [3.0, 4.0]]) # works with any shape tensor >>> sess.run(func(tensor)) array([[ 1., 2.], [ 3., 4.]], dtype=float32) """ from sympy.core.symbol import Symbol # If the user hasn't specified any modules, use what is available. if modules is None: try: _import("scipy") except ImportError: try: _import("numpy") except ImportError: # Use either numpy (if available) or python.math where possible. # XXX: This leads to different behaviour on different systems and # might be the reason for irreproducible errors. modules = ["math", "mpmath", "sympy"] else: modules = ["numpy"] else: modules = ["scipy", "numpy"] # Get the needed namespaces. namespaces = [] # First find any function implementations if use_imps: namespaces.append(_imp_namespace(expr)) # Check for dict before iterating if isinstance(modules, (dict, str)) or not hasattr(modules, '__iter__'): namespaces.append(modules) else: # consistency check if _module_present('numexpr', modules) and len(modules) > 1: raise TypeError("numexpr must be the only item in 'modules'") namespaces += list(modules) # fill namespace with first having highest priority namespace = {} for m in namespaces[::-1]: buf = _get_namespace(m) namespace.update(buf) if hasattr(expr, "atoms"): #Try if you can extract symbols from the expression. #Move on if expr.atoms in not implemented. syms = expr.atoms(Symbol) for term in syms: namespace.update({str(term): term}) if printer is None: if _module_present('mpmath', namespaces): from sympy.printing.pycode import MpmathPrinter as Printer elif _module_present('scipy', namespaces): from sympy.printing.pycode import SciPyPrinter as Printer elif _module_present('numpy', namespaces): from sympy.printing.pycode import NumPyPrinter as Printer elif _module_present('numexpr', namespaces): from sympy.printing.lambdarepr import NumExprPrinter as Printer elif _module_present('tensorflow', namespaces): from sympy.printing.tensorflow import TensorflowPrinter as Printer elif _module_present('sympy', namespaces): from sympy.printing.pycode import SymPyPrinter as Printer else: from sympy.printing.pycode import PythonCodePrinter as Printer user_functions = {} for m in namespaces[::-1]: if isinstance(m, dict): for k in m: user_functions[k] = k printer = Printer({'fully_qualified_modules': False, 'inline': True, 'allow_unknown_functions': True, 'user_functions': user_functions}) # Get the names of the args, for creating a docstring if not iterable(args): args = (args,) names = [] # Grab the callers frame, for getting the names by inspection (if needed) callers_local_vars = inspect.currentframe().f_back.f_locals.items() for n, var in enumerate(args): if hasattr(var, 'name'): names.append(var.name) else: # It's an iterable. Try to get name by inspection of calling frame. name_list = [var_name for var_name, var_val in callers_local_vars if var_val is var] if len(name_list) == 1: names.append(name_list[0]) else: # Cannot infer name with certainty. arg_# will have to do. names.append('arg_' + str(n)) imp_mod_lines = [] for mod, keys in (getattr(printer, 'module_imports', None) or {}).items(): for k in keys: if k not in namespace: imp_mod_lines.append("from %s import %s" % (mod, k)) for ln in imp_mod_lines: exec_(ln, {}, namespace) # Provide lambda expression with builtins, and compatible implementation of range namespace.update({'builtins':builtins, 'range':range}) # Create the function definition code and execute it funcname = '_lambdifygenerated' if _module_present('tensorflow', namespaces): funcprinter = _TensorflowEvaluatorPrinter(printer, dummify) else: funcprinter = _EvaluatorPrinter(printer, dummify) funcstr = funcprinter.doprint(funcname, args, expr) funclocals = {} global _lambdify_generated_counter filename = '<lambdifygenerated-%s>' % _lambdify_generated_counter _lambdify_generated_counter += 1 c = compile(funcstr, filename, 'exec') exec_(c, namespace, funclocals) # mtime has to be None or else linecache.checkcache will remove it linecache.cache[filename] = (len(funcstr), None, funcstr.splitlines(True), filename) func = funclocals[funcname] # Apply the docstring sig = "func({0})".format(", ".join(str(i) for i in names)) sig = textwrap.fill(sig, subsequent_indent=' '*8) expr_str = str(expr) if len(expr_str) > 78: expr_str = textwrap.wrap(expr_str, 75)[0] + '...' func.__doc__ = ( "Created with lambdify. Signature:\n\n" "{sig}\n\n" "Expression:\n\n" "{expr}\n\n" "Source code:\n\n" "{src}\n\n" "Imported modules:\n\n" "{imp_mods}" ).format(sig=sig, expr=expr_str, src=funcstr, imp_mods='\n'.join(imp_mod_lines)) return func def _module_present(modname, modlist): if modname in modlist: return True for m in modlist: if hasattr(m, '__name__') and m.__name__ == modname: return True return False def _get_namespace(m): """ This is used by _lambdify to parse its arguments. """ if isinstance(m, string_types): _import(m) return MODULES[m][0] elif isinstance(m, dict): return m elif hasattr(m, "__dict__"): return m.__dict__ else: raise TypeError("Argument must be either a string, dict or module but it is: %s" % m) def lambdastr(args, expr, printer=None, dummify=None): """ Returns a string that can be evaluated to a lambda function. Examples ======== >>> from sympy.abc import x, y, z >>> from sympy.utilities.lambdify import lambdastr >>> lambdastr(x, x**2) 'lambda x: (x**2)' >>> lambdastr((x,y,z), [z,y,x]) 'lambda x,y,z: ([z, y, x])' Although tuples may not appear as arguments to lambda in Python 3, lambdastr will create a lambda function that will unpack the original arguments so that nested arguments can be handled: >>> lambdastr((x, (y, z)), x + y) 'lambda _0,_1: (lambda x,y,z: (x + y))(_0,_1[0],_1[1])' """ # Transforming everything to strings. from sympy.matrices import DeferredVector from sympy import Dummy, sympify, Symbol, Function, flatten, Derivative, Basic if printer is not None: if inspect.isfunction(printer): lambdarepr = printer else: if inspect.isclass(printer): lambdarepr = lambda expr: printer().doprint(expr) else: lambdarepr = lambda expr: printer.doprint(expr) else: #XXX: This has to be done here because of circular imports from sympy.printing.lambdarepr import lambdarepr def sub_args(args, dummies_dict): if isinstance(args, str): return args elif isinstance(args, DeferredVector): return str(args) elif iterable(args): dummies = flatten([sub_args(a, dummies_dict) for a in args]) return ",".join(str(a) for a in dummies) else: # replace these with Dummy symbols if isinstance(args, (Function, Symbol, Derivative)): dummies = Dummy() dummies_dict.update({args : dummies}) return str(dummies) else: return str(args) def sub_expr(expr, dummies_dict): try: expr = sympify(expr).xreplace(dummies_dict) except Exception: if isinstance(expr, DeferredVector): pass elif isinstance(expr, dict): k = [sub_expr(sympify(a), dummies_dict) for a in expr.keys()] v = [sub_expr(sympify(a), dummies_dict) for a in expr.values()] expr = dict(zip(k, v)) elif isinstance(expr, tuple): expr = tuple(sub_expr(sympify(a), dummies_dict) for a in expr) elif isinstance(expr, list): expr = [sub_expr(sympify(a), dummies_dict) for a in expr] return expr # Transform args def isiter(l): return iterable(l, exclude=(str, DeferredVector, NotIterable)) def flat_indexes(iterable): n = 0 for el in iterable: if isiter(el): for ndeep in flat_indexes(el): yield (n,) + ndeep else: yield (n,) n += 1 if dummify is None: dummify = any(isinstance(a, Basic) and a.atoms(Function, Derivative) for a in ( args if isiter(args) else [args])) if isiter(args) and any(isiter(i) for i in args): dum_args = [str(Dummy(str(i))) for i in range(len(args))] indexed_args = ','.join([ dum_args[ind[0]] + ''.join(["[%s]" % k for k in ind[1:]]) for ind in flat_indexes(args)]) lstr = lambdastr(flatten(args), expr, printer=printer, dummify=dummify) return 'lambda %s: (%s)(%s)' % (','.join(dum_args), lstr, indexed_args) dummies_dict = {} if dummify: args = sub_args(args, dummies_dict) else: if isinstance(args, str): pass elif iterable(args, exclude=DeferredVector): args = ",".join(str(a) for a in args) # Transform expr if dummify: if isinstance(expr, str): pass else: expr = sub_expr(expr, dummies_dict) expr = lambdarepr(expr) return "lambda %s: (%s)" % (args, expr) class _EvaluatorPrinter(object): def __init__(self, printer=None, dummify=False): self._dummify = dummify #XXX: This has to be done here because of circular imports from sympy.printing.lambdarepr import LambdaPrinter if printer is None: printer = LambdaPrinter() if inspect.isfunction(printer): self._exprrepr = printer else: if inspect.isclass(printer): printer = printer() self._exprrepr = printer.doprint if hasattr(printer, '_print_Symbol'): symbolrepr = printer._print_Symbol if hasattr(printer, '_print_Dummy'): dummyrepr = printer._print_Dummy # Used to print the generated function arguments in a standard way self._argrepr = LambdaPrinter().doprint def doprint(self, funcname, args, expr): """Returns the function definition code as a string.""" from sympy import Dummy funcbody = [] if not iterable(args): args = [args] argstrs, expr = self._preprocess(args, expr) # Generate argument unpacking and final argument list funcargs = [] unpackings = [] for argstr in argstrs: if iterable(argstr): funcargs.append(self._argrepr(Dummy())) unpackings.extend(self._print_unpacking(argstr, funcargs[-1])) else: funcargs.append(argstr) funcsig = 'def {}({}):'.format(funcname, ', '.join(funcargs)) # Wrap input arguments before unpacking funcbody.extend(self._print_funcargwrapping(funcargs)) funcbody.extend(unpackings) funcbody.append('return ({})'.format(self._exprrepr(expr))) funclines = [funcsig] funclines.extend(' ' + line for line in funcbody) return '\n'.join(funclines) + '\n' if PY3: @classmethod def _is_safe_ident(cls, ident): return isinstance(ident, str) and ident.isidentifier() \ and not keyword.iskeyword(ident) else: _safe_ident_re = re.compile('^[a-zA-Z_][a-zA-Z0-9_]*$') @classmethod def _is_safe_ident(cls, ident): return isinstance(ident, str) and cls._safe_ident_re.match(ident) \ and not (keyword.iskeyword(ident) or ident == 'None') def _preprocess(self, args, expr): """Preprocess args, expr to replace arguments that do not map to valid Python identifiers. Returns string form of args, and updated expr. """ from sympy import Dummy, Function, flatten, Derivative, ordered, Basic from sympy.matrices import DeferredVector # Args of type Dummy can cause name collisions with args # of type Symbol. Force dummify of everything in this # situation. dummify = self._dummify or any( isinstance(arg, Dummy) for arg in flatten(args)) argstrs = [None]*len(args) for arg, i in reversed(list(ordered(zip(args, range(len(args)))))): if iterable(arg): s, expr = self._preprocess(arg, expr) elif isinstance(arg, DeferredVector): s = str(arg) elif isinstance(arg, Basic) and arg.is_symbol: s = self._argrepr(arg) if dummify or not self._is_safe_ident(s): dummy = Dummy() s = self._argrepr(dummy) expr = self._subexpr(expr, {arg: dummy}) elif dummify or isinstance(arg, (Function, Derivative)): dummy = Dummy() s = self._argrepr(dummy) expr = self._subexpr(expr, {arg: dummy}) else: s = str(arg) argstrs[i] = s return argstrs, expr def _subexpr(self, expr, dummies_dict): from sympy.matrices import DeferredVector from sympy import sympify try: expr = sympify(expr).xreplace(dummies_dict) except AttributeError: if isinstance(expr, DeferredVector): pass elif isinstance(expr, dict): k = [self._subexpr(sympify(a), dummies_dict) for a in expr.keys()] v = [self._subexpr(sympify(a), dummies_dict) for a in expr.values()] expr = dict(zip(k, v)) elif isinstance(expr, tuple): expr = tuple(self._subexpr(sympify(a), dummies_dict) for a in expr) elif isinstance(expr, list): expr = [self._subexpr(sympify(a), dummies_dict) for a in expr] return expr def _print_funcargwrapping(self, args): """Generate argument wrapping code. args is the argument list of the generated function (strings). Return value is a list of lines of code that will be inserted at the beginning of the function definition. """ return [] def _print_unpacking(self, unpackto, arg): """Generate argument unpacking code. arg is the function argument to be unpacked (a string), and unpackto is a list or nested lists of the variable names (strings) to unpack to. """ def unpack_lhs(lvalues): return '[{}]'.format(', '.join( unpack_lhs(val) if iterable(val) else val for val in lvalues)) return ['{} = {}'.format(unpack_lhs(unpackto), arg)] class _TensorflowEvaluatorPrinter(_EvaluatorPrinter): def _print_unpacking(self, lvalues, rvalue): """Generate argument unpacking code. This method is used when the input value is not interable, but can be indexed (see issue #14655). """ from sympy import flatten def flat_indexes(elems): n = 0 for el in elems: if iterable(el): for ndeep in flat_indexes(el): yield (n,) + ndeep else: yield (n,) n += 1 indexed = ', '.join('{}[{}]'.format(rvalue, ']['.join(map(str, ind))) for ind in flat_indexes(lvalues)) return ['[{}] = [{}]'.format(', '.join(flatten(lvalues)), indexed)] def _imp_namespace(expr, namespace=None): """ Return namespace dict with function implementations We need to search for functions in anything that can be thrown at us - that is - anything that could be passed as `expr`. Examples include sympy expressions, as well as tuples, lists and dicts that may contain sympy expressions. Parameters ---------- expr : object Something passed to lambdify, that will generate valid code from ``str(expr)``. namespace : None or mapping Namespace to fill. None results in new empty dict Returns ------- namespace : dict dict with keys of implemented function names within `expr` and corresponding values being the numerical implementation of function Examples ======== >>> from sympy.abc import x >>> from sympy.utilities.lambdify import implemented_function, _imp_namespace >>> from sympy import Function >>> f = implemented_function(Function('f'), lambda x: x+1) >>> g = implemented_function(Function('g'), lambda x: x*10) >>> namespace = _imp_namespace(f(g(x))) >>> sorted(namespace.keys()) ['f', 'g'] """ # Delayed import to avoid circular imports from sympy.core.function import FunctionClass if namespace is None: namespace = {} # tuples, lists, dicts are valid expressions if is_sequence(expr): for arg in expr: _imp_namespace(arg, namespace) return namespace elif isinstance(expr, dict): for key, val in expr.items(): # functions can be in dictionary keys _imp_namespace(key, namespace) _imp_namespace(val, namespace) return namespace # sympy expressions may be Functions themselves func = getattr(expr, 'func', None) if isinstance(func, FunctionClass): imp = getattr(func, '_imp_', None) if imp is not None: name = expr.func.__name__ if name in namespace and namespace[name] != imp: raise ValueError('We found more than one ' 'implementation with name ' '"%s"' % name) namespace[name] = imp # and / or they may take Functions as arguments if hasattr(expr, 'args'): for arg in expr.args: _imp_namespace(arg, namespace) return namespace def implemented_function(symfunc, implementation): """ Add numerical ``implementation`` to function ``symfunc``. ``symfunc`` can be an ``UndefinedFunction`` instance, or a name string. In the latter case we create an ``UndefinedFunction`` instance with that name. Be aware that this is a quick workaround, not a general method to create special symbolic functions. If you want to create a symbolic function to be used by all the machinery of SymPy you should subclass the ``Function`` class. Parameters ---------- symfunc : ``str`` or ``UndefinedFunction`` instance If ``str``, then create new ``UndefinedFunction`` with this as name. If `symfunc` is an Undefined function, create a new function with the same name and the implemented function attached. implementation : callable numerical implementation to be called by ``evalf()`` or ``lambdify`` Returns ------- afunc : sympy.FunctionClass instance function with attached implementation Examples ======== >>> from sympy.abc import x >>> from sympy.utilities.lambdify import lambdify, implemented_function >>> from sympy import Function >>> f = implemented_function('f', lambda x: x+1) >>> lam_f = lambdify(x, f(x)) >>> lam_f(4) 5 """ # Delayed import to avoid circular imports from sympy.core.function import UndefinedFunction # if name, create function to hold implementation _extra_kwargs = {} if isinstance(symfunc, UndefinedFunction): _extra_kwargs = symfunc._extra_kwargs symfunc = symfunc.__name__ if isinstance(symfunc, string_types): # Keyword arguments to UndefinedFunction are added as attributes to # the created class. symfunc = UndefinedFunction(symfunc, _imp_=staticmethod(implementation), **_extra_kwargs) elif not isinstance(symfunc, UndefinedFunction): raise ValueError('symfunc should be either a string or' ' an UndefinedFunction instance.') return symfunc

e45969b507ef1a426f934618eb62a0bbb0dd76cd7506d85d4c8485ba12c58659

from __future__ import print_function, division from sympy.core.compatibility import range """ Algorithms and classes to support enumerative combinatorics. Currently just multiset partitions, but more could be added. Terminology (following Knuth, algorithm 7.1.2.5M TAOCP) *multiset* aaabbcccc has a *partition* aaabc | bccc The submultisets, aaabc and bccc of the partition are called *parts*, or sometimes *vectors*. (Knuth notes that multiset partitions can be thought of as partitions of vectors of integers, where the ith element of the vector gives the multiplicity of element i.) The values a, b and c are *components* of the multiset. These correspond to elements of a set, but in a multiset can be present with a multiplicity greater than 1. The algorithm deserves some explanation. Think of the part aaabc from the multiset above. If we impose an ordering on the components of the multiset, we can represent a part with a vector, in which the value of the first element of the vector corresponds to the multiplicity of the first component in that part. Thus, aaabc can be represented by the vector [3, 1, 1]. We can also define an ordering on parts, based on the lexicographic ordering of the vector (leftmost vector element, i.e., the element with the smallest component number, is the most significant), so that [3, 1, 1] > [3, 1, 0] and [3, 1, 1] > [2, 1, 4]. The ordering on parts can be extended to an ordering on partitions: First, sort the parts in each partition, left-to-right in decreasing order. Then partition A is greater than partition B if A's leftmost/greatest part is greater than B's leftmost part. If the leftmost parts are equal, compare the second parts, and so on. In this ordering, the greatest partition of a given multiset has only one part. The least partition is the one in which the components are spread out, one per part. The enumeration algorithms in this file yield the partitions of the argument multiset in decreasing order. The main data structure is a stack of parts, corresponding to the current partition. An important invariant is that the parts on the stack are themselves in decreasing order. This data structure is decremented to find the next smaller partition. Most often, decrementing the partition will only involve adjustments to the smallest parts at the top of the stack, much as adjacent integers *usually* differ only in their last few digits. Knuth's algorithm uses two main operations on parts: Decrement - change the part so that it is smaller in the (vector) lexicographic order, but reduced by the smallest amount possible. For example, if the multiset has vector [5, 3, 1], and the bottom/greatest part is [4, 2, 1], this part would decrement to [4, 2, 0], while [4, 0, 0] would decrement to [3, 3, 1]. A singleton part is never decremented -- [1, 0, 0] is not decremented to [0, 3, 1]. Instead, the decrement operator needs to fail for this case. In Knuth's pseudocode, the decrement operator is step m5. Spread unallocated multiplicity - Once a part has been decremented, it cannot be the rightmost part in the partition. There is some multiplicity that has not been allocated, and new parts must be created above it in the stack to use up this multiplicity. To maintain the invariant that the parts on the stack are in decreasing order, these new parts must be less than or equal to the decremented part. For example, if the multiset is [5, 3, 1], and its most significant part has just been decremented to [5, 3, 0], the spread operation will add a new part so that the stack becomes [[5, 3, 0], [0, 0, 1]]. If the most significant part (for the same multiset) has been decremented to [2, 0, 0] the stack becomes [[2, 0, 0], [2, 0, 0], [1, 3, 1]]. In the pseudocode, the spread operation for one part is step m2. The complete spread operation is a loop of steps m2 and m3. In order to facilitate the spread operation, Knuth stores, for each component of each part, not just the multiplicity of that component in the part, but also the total multiplicity available for this component in this part or any lesser part above it on the stack. One added twist is that Knuth does not represent the part vectors as arrays. Instead, he uses a sparse representation, in which a component of a part is represented as a component number (c), plus the multiplicity of the component in that part (v) as well as the total multiplicity available for that component (u). This saves time that would be spent skipping over zeros. """ class PartComponent(object): """Internal class used in support of the multiset partitions enumerators and the associated visitor functions. Represents one component of one part of the current partition. A stack of these, plus an auxiliary frame array, f, represents a partition of the multiset. Knuth's pseudocode makes c, u, and v separate arrays. """ __slots__ = ('c', 'u', 'v') def __init__(self): self.c = 0 # Component number self.u = 0 # The as yet unpartitioned amount in component c # *before* it is allocated by this triple self.v = 0 # Amount of c component in the current part # (v<=u). An invariant of the representation is # that the next higher triple for this component # (if there is one) will have a value of u-v in # its u attribute. def __repr__(self): "for debug/algorithm animation purposes" return 'c:%d u:%d v:%d' % (self.c, self.u, self.v) def __eq__(self, other): """Define value oriented equality, which is useful for testers""" return (isinstance(other, self.__class__) and self.c == other.c and self.u == other.u and self.v == other.v) def __ne__(self, other): """Defined for consistency with __eq__""" return not self == other # This function tries to be a faithful implementation of algorithm # 7.1.2.5M in Volume 4A, Combinatoral Algorithms, Part 1, of The Art # of Computer Programming, by Donald Knuth. This includes using # (mostly) the same variable names, etc. This makes for rather # low-level Python. # Changes from Knuth's pseudocode include # - use PartComponent struct/object instead of 3 arrays # - make the function a generator # - map (with some difficulty) the GOTOs to Python control structures. # - Knuth uses 1-based numbering for components, this code is 0-based # - renamed variable l to lpart. # - flag variable x takes on values True/False instead of 1/0 # def multiset_partitions_taocp(multiplicities): """Enumerates partitions of a multiset. Parameters ========== multiplicities list of integer multiplicities of the components of the multiset. Yields ====== state Internal data structure which encodes a particular partition. This output is then usually processed by a vistor function which combines the information from this data structure with the components themselves to produce an actual partition. Unless they wish to create their own visitor function, users will have little need to look inside this data structure. But, for reference, it is a 3-element list with components: f is a frame array, which is used to divide pstack into parts. lpart points to the base of the topmost part. pstack is an array of PartComponent objects. The ``state`` output offers a peek into the internal data structures of the enumeration function. The client should treat this as read-only; any modification of the data structure will cause unpredictable (and almost certainly incorrect) results. Also, the components of ``state`` are modified in place at each iteration. Hence, the visitor must be called at each loop iteration. Accumulating the ``state`` instances and processing them later will not work. Examples ======== >>> from sympy.utilities.enumerative import list_visitor >>> from sympy.utilities.enumerative import multiset_partitions_taocp >>> # variables components and multiplicities represent the multiset 'abb' >>> components = 'ab' >>> multiplicities = [1, 2] >>> states = multiset_partitions_taocp(multiplicities) >>> list(list_visitor(state, components) for state in states) [[['a', 'b', 'b']], [['a', 'b'], ['b']], [['a'], ['b', 'b']], [['a'], ['b'], ['b']]] See Also ======== sympy.utilities.iterables.multiset_partitions: Takes a multiset as input and directly yields multiset partitions. It dispatches to a number of functions, including this one, for implementation. Most users will find it more convenient to use than multiset_partitions_taocp. """ # Important variables. # m is the number of components, i.e., number of distinct elements m = len(multiplicities) # n is the cardinality, total number of elements whether or not distinct n = sum(multiplicities) # The main data structure, f segments pstack into parts. See # list_visitor() for example code indicating how this internal # state corresponds to a partition. # Note: allocation of space for stack is conservative. Knuth's # exercise 7.2.1.5.68 gives some indication of how to tighten this # bound, but this is not implemented. pstack = [PartComponent() for i in range(n * m + 1)] f = [0] * (n + 1) # Step M1 in Knuth (Initialize) # Initial state - entire multiset in one part. for j in range(m): ps = pstack[j] ps.c = j ps.u = multiplicities[j] ps.v = multiplicities[j] # Other variables f[0] = 0 a = 0 lpart = 0 f[1] = m b = m # in general, current stack frame is from a to b - 1 while True: while True: # Step M2 (Subtract v from u) j = a k = b x = False while j < b: pstack[k].u = pstack[j].u - pstack[j].v if pstack[k].u == 0: x = True elif not x: pstack[k].c = pstack[j].c pstack[k].v = min(pstack[j].v, pstack[k].u) x = pstack[k].u < pstack[j].v k = k + 1 else: # x is True pstack[k].c = pstack[j].c pstack[k].v = pstack[k].u k = k + 1 j = j + 1 # Note: x is True iff v has changed # Step M3 (Push if nonzero.) if k > b: a = b b = k lpart = lpart + 1 f[lpart + 1] = b # Return to M2 else: break # Continue to M4 # M4 Visit a partition state = [f, lpart, pstack] yield state # M5 (Decrease v) while True: j = b-1 while (pstack[j].v == 0): j = j - 1 if j == a and pstack[j].v == 1: # M6 (Backtrack) if lpart == 0: return lpart = lpart - 1 b = a a = f[lpart] # Return to M5 else: pstack[j].v = pstack[j].v - 1 for k in range(j + 1, b): pstack[k].v = pstack[k].u break # GOTO M2 # --------------- Visitor functions for multiset partitions --------------- # A visitor takes the partition state generated by # multiset_partitions_taocp or other enumerator, and produces useful # output (such as the actual partition). def factoring_visitor(state, primes): """Use with multiset_partitions_taocp to enumerate the ways a number can be expressed as a product of factors. For this usage, the exponents of the prime factors of a number are arguments to the partition enumerator, while the corresponding prime factors are input here. Examples ======== To enumerate the factorings of a number we can think of the elements of the partition as being the prime factors and the multiplicities as being their exponents. >>> from sympy.utilities.enumerative import factoring_visitor >>> from sympy.utilities.enumerative import multiset_partitions_taocp >>> from sympy import factorint >>> primes, multiplicities = zip(*factorint(24).items()) >>> primes (2, 3) >>> multiplicities (3, 1) >>> states = multiset_partitions_taocp(multiplicities) >>> list(factoring_visitor(state, primes) for state in states) [[24], [8, 3], [12, 2], [4, 6], [4, 2, 3], [6, 2, 2], [2, 2, 2, 3]] """ f, lpart, pstack = state factoring = [] for i in range(lpart + 1): factor = 1 for ps in pstack[f[i]: f[i + 1]]: if ps.v > 0: factor *= primes[ps.c] ** ps.v factoring.append(factor) return factoring def list_visitor(state, components): """Return a list of lists to represent the partition. Examples ======== >>> from sympy.utilities.enumerative import list_visitor >>> from sympy.utilities.enumerative import multiset_partitions_taocp >>> states = multiset_partitions_taocp([1, 2, 1]) >>> s = next(states) >>> list_visitor(s, 'abc') # for multiset 'a b b c' [['a', 'b', 'b', 'c']] >>> s = next(states) >>> list_visitor(s, [1, 2, 3]) # for multiset '1 2 2 3 [[1, 2, 2], [3]] """ f, lpart, pstack = state partition = [] for i in range(lpart+1): part = [] for ps in pstack[f[i]:f[i+1]]: if ps.v > 0: part.extend([components[ps.c]] * ps.v) partition.append(part) return partition class MultisetPartitionTraverser(): """ Has methods to ``enumerate`` and ``count`` the partitions of a multiset. This implements a refactored and extended version of Knuth's algorithm 7.1.2.5M [AOCP]_." The enumeration methods of this class are generators and return data structures which can be interpreted by the same visitor functions used for the output of ``multiset_partitions_taocp``. Examples ======== >>> from sympy.utilities.enumerative import MultisetPartitionTraverser >>> m = MultisetPartitionTraverser() >>> m.count_partitions([4,4,4,2]) 127750 >>> m.count_partitions([3,3,3]) 686 See Also ======== multiset_partitions_taocp sympy.utilities.iterables.multiset_partititions References ========== .. [AOCP] Algorithm 7.1.2.5M in Volume 4A, Combinatoral Algorithms, Part 1, of The Art of Computer Programming, by Donald Knuth. .. [Factorisatio] On a Problem of Oppenheim concerning "Factorisatio Numerorum" E. R. Canfield, Paul Erdos, Carl Pomerance, JOURNAL OF NUMBER THEORY, Vol. 17, No. 1. August 1983. See section 7 for a description of an algorithm similar to Knuth's. .. [Yorgey] Generating Multiset Partitions, Brent Yorgey, The Monad.Reader, Issue 8, September 2007. """ def __init__(self): self.debug = False # TRACING variables. These are useful for gathering # statistics on the algorithm itself, but have no particular # benefit to a user of the code. self.k1 = 0 self.k2 = 0 self.p1 = 0 def db_trace(self, msg): """Useful for usderstanding/debugging the algorithms. Not generally activated in end-user code.""" if self.debug: letters = 'abcdefghijklmnopqrstuvwxyz' state = [self.f, self.lpart, self.pstack] print("DBG:", msg, ["".join(part) for part in list_visitor(state, letters)], animation_visitor(state)) # # Helper methods for enumeration # def _initialize_enumeration(self, multiplicities): """Allocates and initializes the partition stack. This is called from the enumeration/counting routines, so there is no need to call it separately.""" num_components = len(multiplicities) # cardinality is the total number of elements, whether or not distinct cardinality = sum(multiplicities) # pstack is the partition stack, which is segmented by # f into parts. self.pstack = [PartComponent() for i in range(num_components * cardinality + 1)] self.f = [0] * (cardinality + 1) # Initial state - entire multiset in one part. for j in range(num_components): ps = self.pstack[j] ps.c = j ps.u = multiplicities[j] ps.v = multiplicities[j] self.f[0] = 0 self.f[1] = num_components self.lpart = 0 # The decrement_part() method corresponds to step M5 in Knuth's # algorithm. This is the base version for enum_all(). Modified # versions of this method are needed if we want to restrict # sizes of the partitions produced. def decrement_part(self, part): """Decrements part (a subrange of pstack), if possible, returning True iff the part was successfully decremented. If you think of the v values in the part as a multi-digit integer (least significant digit on the right) this is basically decrementing that integer, but with the extra constraint that the leftmost digit cannot be decremented to 0. Parameters ========== part The part, represented as a list of PartComponent objects, which is to be decremented. """ plen = len(part) for j in range(plen - 1, -1, -1): if (j == 0 and part[j].v > 1) or (j > 0 and part[j].v > 0): # found val to decrement part[j].v -= 1 # Reset trailing parts back to maximum for k in range(j + 1, plen): part[k].v = part[k].u return True return False # Version to allow number of parts to be bounded from above. # Corresponds to (a modified) step M5. def decrement_part_small(self, part, ub): """Decrements part (a subrange of pstack), if possible, returning True iff the part was successfully decremented. Parameters ========== part part to be decremented (topmost part on the stack) ub the maximum number of parts allowed in a partition returned by the calling traversal. Notes ===== The goal of this modification of the ordinary decrement method is to fail (meaning that the subtree rooted at this part is to be skipped) when it can be proved that this part can only have child partitions which are larger than allowed by ``ub``. If a decision is made to fail, it must be accurate, otherwise the enumeration will miss some partitions. But, it is OK not to capture all the possible failures -- if a part is passed that shouldn't be, the resulting too-large partitions are filtered by the enumeration one level up. However, as is usual in constrained enumerations, failing early is advantageous. The tests used by this method catch the most common cases, although this implementation is by no means the last word on this problem. The tests include: 1) ``lpart`` must be less than ``ub`` by at least 2. This is because once a part has been decremented, the partition will gain at least one child in the spread step. 2) If the leading component of the part is about to be decremented, check for how many parts will be added in order to use up the unallocated multiplicity in that leading component, and fail if this number is greater than allowed by ``ub``. (See code for the exact expression.) This test is given in the answer to Knuth's problem 7.2.1.5.69. 3) If there is *exactly* enough room to expand the leading component by the above test, check the next component (if it exists) once decrementing has finished. If this has ``v == 0``, this next component will push the expansion over the limit by 1, so fail. """ if self.lpart >= ub - 1: self.p1 += 1 # increment to keep track of usefulness of tests return False plen = len(part) for j in range(plen - 1, -1, -1): # Knuth's mod, (answer to problem 7.2.1.5.69) if (j == 0) and (part[0].v - 1)*(ub - self.lpart) < part[0].u: self.k1 += 1 return False if (j == 0 and part[j].v > 1) or (j > 0 and part[j].v > 0): # found val to decrement part[j].v -= 1 # Reset trailing parts back to maximum for k in range(j + 1, plen): part[k].v = part[k].u # Have now decremented part, but are we doomed to # failure when it is expanded? Check one oddball case # that turns out to be surprisingly common - exactly # enough room to expand the leading component, but no # room for the second component, which has v=0. if (plen > 1 and (part[1].v == 0) and (part[0].u - part[0].v) == ((ub - self.lpart - 1) * part[0].v)): self.k2 += 1 self.db_trace("Decrement fails test 3") return False return True return False def decrement_part_large(self, part, amt, lb): """Decrements part, while respecting size constraint. A part can have no children which are of sufficient size (as indicated by ``lb``) unless that part has sufficient unallocated multiplicity. When enforcing the size constraint, this method will decrement the part (if necessary) by an amount needed to ensure sufficient unallocated multiplicity. Returns True iff the part was successfully decremented. Parameters ========== part part to be decremented (topmost part on the stack) amt Can only take values 0 or 1. A value of 1 means that the part must be decremented, and then the size constraint is enforced. A value of 0 means just to enforce the ``lb`` size constraint. lb The partitions produced by the calling enumeration must have more parts than this value. """ if amt == 1: # In this case we always need to increment, *before* # enforcing the "sufficient unallocated multiplicity" # constraint. Easiest for this is just to call the # regular decrement method. if not self.decrement_part(part): return False # Next, perform any needed additional decrementing to respect # "sufficient unallocated multiplicity" (or fail if this is # not possible). min_unalloc = lb - self.lpart if min_unalloc <= 0: return True total_mult = sum(pc.u for pc in part) total_alloc = sum(pc.v for pc in part) if total_mult <= min_unalloc: return False deficit = min_unalloc - (total_mult - total_alloc) if deficit <= 0: return True for i in range(len(part) - 1, -1, -1): if i == 0: if part[0].v > deficit: part[0].v -= deficit return True else: return False # This shouldn't happen, due to above check else: if part[i].v >= deficit: part[i].v -= deficit return True else: deficit -= part[i].v part[i].v = 0 def decrement_part_range(self, part, lb, ub): """Decrements part (a subrange of pstack), if possible, returning True iff the part was successfully decremented. Parameters ========== part part to be decremented (topmost part on the stack) ub the maximum number of parts allowed in a partition returned by the calling traversal. lb The partitions produced by the calling enumeration must have more parts than this value. Notes ===== Combines the constraints of _small and _large decrement methods. If returns success, part has been decremented at least once, but perhaps by quite a bit more if needed to meet the lb constraint. """ # Constraint in the range case is just enforcing both the # constraints from _small and _large cases. Note the 0 as the # second argument to the _large call -- this is the signal to # decrement only as needed to for constraint enforcement. The # short circuiting and left-to-right order of the 'and' # operator is important for this to work correctly. return self.decrement_part_small(part, ub) and \ self.decrement_part_large(part, 0, lb) def spread_part_multiplicity(self): """Returns True if a new part has been created, and adjusts pstack, f and lpart as needed. Notes ===== Spreads unallocated multiplicity from the current top part into a new part created above the current on the stack. This new part is constrained to be less than or equal to the old in terms of the part ordering. This call does nothing (and returns False) if the current top part has no unallocated multiplicity. """ j = self.f[self.lpart] # base of current top part k = self.f[self.lpart + 1] # ub of current; potential base of next base = k # save for later comparison changed = False # Set to true when the new part (so far) is # strictly less than (as opposed to less than # or equal) to the old. for j in range(self.f[self.lpart], self.f[self.lpart + 1]): self.pstack[k].u = self.pstack[j].u - self.pstack[j].v if self.pstack[k].u == 0: changed = True else: self.pstack[k].c = self.pstack[j].c if changed: # Put all available multiplicity in this part self.pstack[k].v = self.pstack[k].u else: # Still maintaining ordering constraint if self.pstack[k].u < self.pstack[j].v: self.pstack[k].v = self.pstack[k].u changed = True else: self.pstack[k].v = self.pstack[j].v k = k + 1 if k > base: # Adjust for the new part on stack self.lpart = self.lpart + 1 self.f[self.lpart + 1] = k return True return False def top_part(self): """Return current top part on the stack, as a slice of pstack. """ return self.pstack[self.f[self.lpart]:self.f[self.lpart + 1]] # Same interface and functionality as multiset_partitions_taocp(), # but some might find this refactored version easier to follow. def enum_all(self, multiplicities): """Enumerate the partitions of a multiset. Examples ======== >>> from sympy.utilities.enumerative import list_visitor >>> from sympy.utilities.enumerative import MultisetPartitionTraverser >>> m = MultisetPartitionTraverser() >>> states = m.enum_all([2,2]) >>> list(list_visitor(state, 'ab') for state in states) [[['a', 'a', 'b', 'b']], [['a', 'a', 'b'], ['b']], [['a', 'a'], ['b', 'b']], [['a', 'a'], ['b'], ['b']], [['a', 'b', 'b'], ['a']], [['a', 'b'], ['a', 'b']], [['a', 'b'], ['a'], ['b']], [['a'], ['a'], ['b', 'b']], [['a'], ['a'], ['b'], ['b']]] See Also ======== multiset_partitions_taocp(): which provides the same result as this method, but is about twice as fast. Hence, enum_all is primarily useful for testing. Also see the function for a discussion of states and visitors. """ self._initialize_enumeration(multiplicities) while True: while self.spread_part_multiplicity(): pass # M4 Visit a partition state = [self.f, self.lpart, self.pstack] yield state # M5 (Decrease v) while not self.decrement_part(self.top_part()): # M6 (Backtrack) if self.lpart == 0: return self.lpart -= 1 def enum_small(self, multiplicities, ub): """Enumerate multiset partitions with no more than ``ub`` parts. Equivalent to enum_range(multiplicities, 0, ub) Parameters ========== multiplicities list of multiplicities of the components of the multiset. ub Maximum number of parts Examples ======== >>> from sympy.utilities.enumerative import list_visitor >>> from sympy.utilities.enumerative import MultisetPartitionTraverser >>> m = MultisetPartitionTraverser() >>> states = m.enum_small([2,2], 2) >>> list(list_visitor(state, 'ab') for state in states) [[['a', 'a', 'b', 'b']], [['a', 'a', 'b'], ['b']], [['a', 'a'], ['b', 'b']], [['a', 'b', 'b'], ['a']], [['a', 'b'], ['a', 'b']]] The implementation is based, in part, on the answer given to exercise 69, in Knuth [AOCP]_. See Also ======== enum_all, enum_large, enum_range """ # Keep track of iterations which do not yield a partition. # Clearly, we would like to keep this number small. self.discarded = 0 if ub <= 0: return self._initialize_enumeration(multiplicities) while True: good_partition = True while self.spread_part_multiplicity(): self.db_trace("spread 1") if self.lpart >= ub: self.discarded += 1 good_partition = False self.db_trace(" Discarding") self.lpart = ub - 2 break # M4 Visit a partition if good_partition: state = [self.f, self.lpart, self.pstack] yield state # M5 (Decrease v) while not self.decrement_part_small(self.top_part(), ub): self.db_trace("Failed decrement, going to backtrack") # M6 (Backtrack) if self.lpart == 0: return self.lpart -= 1 self.db_trace("Backtracked to") self.db_trace("decrement ok, about to expand") def enum_large(self, multiplicities, lb): """Enumerate the partitions of a multiset with lb < num(parts) Equivalent to enum_range(multiplicities, lb, sum(multiplicities)) Parameters ========== multiplicities list of multiplicities of the components of the multiset. lb Number of parts in the partition must be greater than this lower bound. Examples ======== >>> from sympy.utilities.enumerative import list_visitor >>> from sympy.utilities.enumerative import MultisetPartitionTraverser >>> m = MultisetPartitionTraverser() >>> states = m.enum_large([2,2], 2) >>> list(list_visitor(state, 'ab') for state in states) [[['a', 'a'], ['b'], ['b']], [['a', 'b'], ['a'], ['b']], [['a'], ['a'], ['b', 'b']], [['a'], ['a'], ['b'], ['b']]] See Also ======== enum_all, enum_small, enum_range """ self.discarded = 0 if lb >= sum(multiplicities): return self._initialize_enumeration(multiplicities) self.decrement_part_large(self.top_part(), 0, lb) while True: good_partition = True while self.spread_part_multiplicity(): if not self.decrement_part_large(self.top_part(), 0, lb): # Failure here should be rare/impossible self.discarded += 1 good_partition = False break # M4 Visit a partition if good_partition: state = [self.f, self.lpart, self.pstack] yield state # M5 (Decrease v) while not self.decrement_part_large(self.top_part(), 1, lb): # M6 (Backtrack) if self.lpart == 0: return self.lpart -= 1 def enum_range(self, multiplicities, lb, ub): """Enumerate the partitions of a multiset with ``lb < num(parts) <= ub``. In particular, if partitions with exactly ``k`` parts are desired, call with ``(multiplicities, k - 1, k)``. This method generalizes enum_all, enum_small, and enum_large. Examples ======== >>> from sympy.utilities.enumerative import list_visitor >>> from sympy.utilities.enumerative import MultisetPartitionTraverser >>> m = MultisetPartitionTraverser() >>> states = m.enum_range([2,2], 1, 2) >>> list(list_visitor(state, 'ab') for state in states) [[['a', 'a', 'b'], ['b']], [['a', 'a'], ['b', 'b']], [['a', 'b', 'b'], ['a']], [['a', 'b'], ['a', 'b']]] """ # combine the constraints of the _large and _small # enumerations. self.discarded = 0 if ub <= 0 or lb >= sum(multiplicities): return self._initialize_enumeration(multiplicities) self.decrement_part_large(self.top_part(), 0, lb) while True: good_partition = True while self.spread_part_multiplicity(): self.db_trace("spread 1") if not self.decrement_part_large(self.top_part(), 0, lb): # Failure here - possible in range case? self.db_trace(" Discarding (large cons)") self.discarded += 1 good_partition = False break elif self.lpart >= ub: self.discarded += 1 good_partition = False self.db_trace(" Discarding small cons") self.lpart = ub - 2 break # M4 Visit a partition if good_partition: state = [self.f, self.lpart, self.pstack] yield state # M5 (Decrease v) while not self.decrement_part_range(self.top_part(), lb, ub): self.db_trace("Failed decrement, going to backtrack") # M6 (Backtrack) if self.lpart == 0: return self.lpart -= 1 self.db_trace("Backtracked to") self.db_trace("decrement ok, about to expand") def count_partitions_slow(self, multiplicities): """Returns the number of partitions of a multiset whose elements have the multiplicities given in ``multiplicities``. Primarily for comparison purposes. It follows the same path as enumerate, and counts, rather than generates, the partitions. See Also ======== count_partitions Has the same calling interface, but is much faster. """ # number of partitions so far in the enumeration self.pcount = 0 self._initialize_enumeration(multiplicities) while True: while self.spread_part_multiplicity(): pass # M4 Visit (count) a partition self.pcount += 1 # M5 (Decrease v) while not self.decrement_part(self.top_part()): # M6 (Backtrack) if self.lpart == 0: return self.pcount self.lpart -= 1 def count_partitions(self, multiplicities): """Returns the number of partitions of a multiset whose components have the multiplicities given in ``multiplicities``. For larger counts, this method is much faster than calling one of the enumerators and counting the result. Uses dynamic programming to cut down on the number of nodes actually explored. The dictionary used in order to accelerate the counting process is stored in the ``MultisetPartitionTraverser`` object and persists across calls. If the user does not expect to call ``count_partitions`` for any additional multisets, the object should be cleared to save memory. On the other hand, the cache built up from one count run can significantly speed up subsequent calls to ``count_partitions``, so it may be advantageous not to clear the object. Examples ======== >>> from sympy.utilities.enumerative import MultisetPartitionTraverser >>> m = MultisetPartitionTraverser() >>> m.count_partitions([9,8,2]) 288716 >>> m.count_partitions([2,2]) 9 >>> del m Notes ===== If one looks at the workings of Knuth's algorithm M [AOCP]_, it can be viewed as a traversal of a binary tree of parts. A part has (up to) two children, the left child resulting from the spread operation, and the right child from the decrement operation. The ordinary enumeration of multiset partitions is an in-order traversal of this tree, and with the partitions corresponding to paths from the root to the leaves. The mapping from paths to partitions is a little complicated, since the partition would contain only those parts which are leaves or the parents of a spread link, not those which are parents of a decrement link. For counting purposes, it is sufficient to count leaves, and this can be done with a recursive in-order traversal. The number of leaves of a subtree rooted at a particular part is a function only of that part itself, so memoizing has the potential to speed up the counting dramatically. This method follows a computational approach which is similar to the hypothetical memoized recursive function, but with two differences: 1) This method is iterative, borrowing its structure from the other enumerations and maintaining an explicit stack of parts which are in the process of being counted. (There may be multisets which can be counted reasonably quickly by this implementation, but which would overflow the default Python recursion limit with a recursive implementation.) 2) Instead of using the part data structure directly, a more compact key is constructed. This saves space, but more importantly coalesces some parts which would remain separate with physical keys. Unlike the enumeration functions, there is currently no _range version of count_partitions. If someone wants to stretch their brain, it should be possible to construct one by memoizing with a histogram of counts rather than a single count, and combining the histograms. """ # number of partitions so far in the enumeration self.pcount = 0 # dp_stack is list of lists of (part_key, start_count) pairs self.dp_stack = [] # dp_map is map part_key-> count, where count represents the # number of multiset which are descendants of a part with this # key, **or any of its decrements** # Thus, when we find a part in the map, we add its count # value to the running total, cut off the enumeration, and # backtrack if not hasattr(self, 'dp_map'): self.dp_map = {} self._initialize_enumeration(multiplicities) pkey = part_key(self.top_part()) self.dp_stack.append([(pkey, 0), ]) while True: while self.spread_part_multiplicity(): pkey = part_key(self.top_part()) if pkey in self.dp_map: # Already have a cached value for the count of the # subtree rooted at this part. Add it to the # running counter, and break out of the spread # loop. The -1 below is to compensate for the # leaf that this code path would otherwise find, # and which gets incremented for below. self.pcount += (self.dp_map[pkey] - 1) self.lpart -= 1 break else: self.dp_stack.append([(pkey, self.pcount), ]) # M4 count a leaf partition self.pcount += 1 # M5 (Decrease v) while not self.decrement_part(self.top_part()): # M6 (Backtrack) for key, oldcount in self.dp_stack.pop(): self.dp_map[key] = self.pcount - oldcount if self.lpart == 0: return self.pcount self.lpart -= 1 # At this point have successfully decremented the part on # the stack and it does not appear in the cache. It needs # to be added to the list at the top of dp_stack pkey = part_key(self.top_part()) self.dp_stack[-1].append((pkey, self.pcount),) def part_key(part): """Helper for MultisetPartitionTraverser.count_partitions that creates a key for ``part``, that only includes information which can affect the count for that part. (Any irrelevant information just reduces the effectiveness of dynamic programming.) Notes ===== This member function is a candidate for future exploration. There are likely symmetries that can be exploited to coalesce some ``part_key`` values, and thereby save space and improve performance. """ # The component number is irrelevant for counting partitions, so # leave it out of the memo key. rval = [] for ps in part: rval.append(ps.u) rval.append(ps.v) return tuple(rval)

d6256df7c8c3561d33e0f9b704ff0de425e94cb819cbc89f2e62b2449d731268

from __future__ import print_function, division from sympy.core.compatibility import range from sympy.core.decorators import wraps def recurrence_memo(initial): """ Memo decorator for sequences defined by recurrence See usage examples e.g. in the specfun/combinatorial module """ cache = initial def decorator(f): @wraps(f) def g(n): L = len(cache) if n <= L - 1: return cache[n] for i in range(L, n + 1): cache.append(f(i, cache)) return cache[-1] return g return decorator def assoc_recurrence_memo(base_seq): """ Memo decorator for associated sequences defined by recurrence starting from base base_seq(n) -- callable to get base sequence elements XXX works only for Pn0 = base_seq(0) cases XXX works only for m <= n cases """ cache = [] def decorator(f): @wraps(f) def g(n, m): L = len(cache) if n < L: return cache[n][m] for i in range(L, n + 1): # get base sequence F_i0 = base_seq(i) F_i_cache = [F_i0] cache.append(F_i_cache) # XXX only works for m <= n cases # generate assoc sequence for j in range(1, i + 1): F_ij = f(i, j, cache) F_i_cache.append(F_ij) return cache[n][m] return g return decorator

4d2c8ef4eeffe8ba73f02cf187894d38b0ed513d855efd4e05e6b00e40f583b7

""" Helpers for randomized testing """ from __future__ import print_function, division from random import uniform, Random, randrange, randint from sympy.core.compatibility import is_sequence, as_int from sympy.core.containers import Tuple from sympy.core.numbers import comp, I from sympy.core.symbol import Symbol from sympy.simplify.simplify import nsimplify def random_complex_number(a=2, b=-1, c=3, d=1, rational=False, tolerance=None): """ Return a random complex number. To reduce chance of hitting branch cuts or anything, we guarantee b <= Im z <= d, a <= Re z <= c When rational is True, a rational approximation to a random number is obtained within specified tolerance, if any. """ A, B = uniform(a, c), uniform(b, d) if not rational: return A + I*B return (nsimplify(A, rational=True, tolerance=tolerance) + I*nsimplify(B, rational=True, tolerance=tolerance)) def verify_numerically(f, g, z=None, tol=1.0e-6, a=2, b=-1, c=3, d=1): """ Test numerically that f and g agree when evaluated in the argument z. If z is None, all symbols will be tested. This routine does not test whether there are Floats present with precision higher than 15 digits so if there are, your results may not be what you expect due to round- off errors. Examples ======== >>> from sympy import sin, cos >>> from sympy.abc import x >>> from sympy.utilities.randtest import verify_numerically as tn >>> tn(sin(x)**2 + cos(x)**2, 1, x) True """ f, g, z = Tuple(f, g, z) z = [z] if isinstance(z, Symbol) else (f.free_symbols | g.free_symbols) reps = list(zip(z, [random_complex_number(a, b, c, d) for zi in z])) z1 = f.subs(reps).n() z2 = g.subs(reps).n() return comp(z1, z2, tol) def test_derivative_numerically(f, z, tol=1.0e-6, a=2, b=-1, c=3, d=1): """ Test numerically that the symbolically computed derivative of f with respect to z is correct. This routine does not test whether there are Floats present with precision higher than 15 digits so if there are, your results may not be what you expect due to round-off errors. Examples ======== >>> from sympy import sin >>> from sympy.abc import x >>> from sympy.utilities.randtest import test_derivative_numerically as td >>> td(sin(x), x) True """ from sympy.core.function import Derivative z0 = random_complex_number(a, b, c, d) f1 = f.diff(z).subs(z, z0) f2 = Derivative(f, z).doit_numerically(z0) return comp(f1.n(), f2.n(), tol) def _randrange(seed=None): """Return a randrange generator. ``seed`` can be o None - return randomly seeded generator o int - return a generator seeded with the int o list - the values to be returned will be taken from the list in the order given; the provided list is not modified. Examples ======== >>> from sympy.utilities.randtest import _randrange >>> rr = _randrange() >>> rr(1000) # doctest: +SKIP 999 >>> rr = _randrange(3) >>> rr(1000) # doctest: +SKIP 238 >>> rr = _randrange([0, 5, 1, 3, 4]) >>> rr(3), rr(3) (0, 1) """ if seed is None: return randrange elif isinstance(seed, int): return Random(seed).randrange elif is_sequence(seed): seed = list(seed) # make a copy seed.reverse() def give(a, b=None, seq=seed): if b is None: a, b = 0, a a, b = as_int(a), as_int(b) w = b - a if w < 1: raise ValueError('_randrange got empty range') try: x = seq.pop() except AttributeError: raise ValueError('_randrange expects a list-like sequence') except IndexError: raise ValueError('_randrange sequence was too short') if a <= x < b: return x else: return give(a, b, seq) return give else: raise ValueError('_randrange got an unexpected seed') def _randint(seed=None): """Return a randint generator. ``seed`` can be o None - return randomly seeded generator o int - return a generator seeded with the int o list - the values to be returned will be taken from the list in the order given; the provided list is not modified. Examples ======== >>> from sympy.utilities.randtest import _randint >>> ri = _randint() >>> ri(1, 1000) # doctest: +SKIP 999 >>> ri = _randint(3) >>> ri(1, 1000) # doctest: +SKIP 238 >>> ri = _randint([0, 5, 1, 2, 4]) >>> ri(1, 3), ri(1, 3) (1, 2) """ if seed is None: return randint elif isinstance(seed, int): return Random(seed).randint elif is_sequence(seed): seed = list(seed) # make a copy seed.reverse() def give(a, b, seq=seed): a, b = as_int(a), as_int(b) w = b - a if w < 0: raise ValueError('_randint got empty range') try: x = seq.pop() except AttributeError: raise ValueError('_randint expects a list-like sequence') except IndexError: raise ValueError('_randint sequence was too short') if a <= x <= b: return x else: return give(a, b, seq) return give else: raise ValueError('_randint got an unexpected seed')

50513085c4f7c3bf054a8a1d19a7bbf7e7241c230c1ca22a498612f6e85ab723

""" A Printer which converts an expression into its LaTeX equivalent. """ from __future__ import print_function, division import itertools from sympy.core import S, Add, Symbol, Mod from sympy.core.sympify import SympifyError from sympy.core.alphabets import greeks from sympy.core.operations import AssocOp from sympy.core.containers import Tuple from sympy.logic.boolalg import true from sympy.core.function import (_coeff_isneg, UndefinedFunction, AppliedUndef, Derivative) ## sympy.printing imports from sympy.printing.precedence import precedence_traditional from .printer import Printer from .conventions import split_super_sub, requires_partial from .precedence import precedence, PRECEDENCE import mpmath.libmp as mlib from mpmath.libmp import prec_to_dps from sympy.core.compatibility import default_sort_key, range from sympy.utilities.iterables import has_variety import re # Hand-picked functions which can be used directly in both LaTeX and MathJax # Complete list at https://docs.mathjax.org/en/latest/tex.html#supported-latex-commands # This variable only contains those functions which sympy uses. accepted_latex_functions = ['arcsin', 'arccos', 'arctan', 'sin', 'cos', 'tan', 'sinh', 'cosh', 'tanh', 'sqrt', 'ln', 'log', 'sec', 'csc', 'cot', 'coth', 're', 'im', 'frac', 'root', 'arg', ] tex_greek_dictionary = { 'Alpha': 'A', 'Beta': 'B', 'Gamma': r'\Gamma', 'Delta': r'\Delta', 'Epsilon': 'E', 'Zeta': 'Z', 'Eta': 'H', 'Theta': r'\Theta', 'Iota': 'I', 'Kappa': 'K', 'Lambda': r'\Lambda', 'Mu': 'M', 'Nu': 'N', 'Xi': r'\Xi', 'omicron': 'o', 'Omicron': 'O', 'Pi': r'\Pi', 'Rho': 'P', 'Sigma': r'\Sigma', 'Tau': 'T', 'Upsilon': r'\Upsilon', 'Phi': r'\Phi', 'Chi': 'X', 'Psi': r'\Psi', 'Omega': r'\Omega', 'lamda': r'\lambda', 'Lamda': r'\Lambda', 'khi': r'\chi', 'Khi': r'X', 'varepsilon': r'\varepsilon', 'varkappa': r'\varkappa', 'varphi': r'\varphi', 'varpi': r'\varpi', 'varrho': r'\varrho', 'varsigma': r'\varsigma', 'vartheta': r'\vartheta', } other_symbols = set(['aleph', 'beth', 'daleth', 'gimel', 'ell', 'eth', 'hbar', 'hslash', 'mho', 'wp', ]) # Variable name modifiers modifier_dict = { # Accents 'mathring': lambda s: r'\mathring{'+s+r'}', 'ddddot': lambda s: r'\ddddot{'+s+r'}', 'dddot': lambda s: r'\dddot{'+s+r'}', 'ddot': lambda s: r'\ddot{'+s+r'}', 'dot': lambda s: r'\dot{'+s+r'}', 'check': lambda s: r'\check{'+s+r'}', 'breve': lambda s: r'\breve{'+s+r'}', 'acute': lambda s: r'\acute{'+s+r'}', 'grave': lambda s: r'\grave{'+s+r'}', 'tilde': lambda s: r'\tilde{'+s+r'}', 'hat': lambda s: r'\hat{'+s+r'}', 'bar': lambda s: r'\bar{'+s+r'}', 'vec': lambda s: r'\vec{'+s+r'}', 'prime': lambda s: "{"+s+"}'", 'prm': lambda s: "{"+s+"}'", # Faces 'bold': lambda s: r'\boldsymbol{'+s+r'}', 'bm': lambda s: r'\boldsymbol{'+s+r'}', 'cal': lambda s: r'\mathcal{'+s+r'}', 'scr': lambda s: r'\mathscr{'+s+r'}', 'frak': lambda s: r'\mathfrak{'+s+r'}', # Brackets 'norm': lambda s: r'\left\|{'+s+r'}\right\|', 'avg': lambda s: r'\left\langle{'+s+r'}\right\rangle', 'abs': lambda s: r'\left|{'+s+r'}\right|', 'mag': lambda s: r'\left|{'+s+r'}\right|', } greek_letters_set = frozenset(greeks) _between_two_numbers_p = ( re.compile(r'[0-9][} ]*$'), # search re.compile(r'[{ ]*[-+0-9]'), # match ) class LatexPrinter(Printer): printmethod = "_latex" _default_settings = { "order": None, "mode": "plain", "itex": False, "fold_frac_powers": False, "fold_func_brackets": False, "fold_short_frac": None, "long_frac_ratio": None, "mul_symbol": None, "inv_trig_style": "abbreviated", "mat_str": None, "mat_delim": "[", "symbol_names": {}, "ln_notation": False, } def __init__(self, settings=None): Printer.__init__(self, settings) if 'mode' in self._settings: valid_modes = ['inline', 'plain', 'equation', 'equation*'] if self._settings['mode'] not in valid_modes: raise ValueError("'mode' must be one of 'inline', 'plain', " "'equation' or 'equation*'") if self._settings['fold_short_frac'] is None and \ self._settings['mode'] == 'inline': self._settings['fold_short_frac'] = True mul_symbol_table = { None: r" ", "ldot": r" \,.\, ", "dot": r" \cdot ", "times": r" \times " } try: self._settings['mul_symbol_latex'] = \ mul_symbol_table[self._settings['mul_symbol']] except KeyError: self._settings['mul_symbol_latex'] = \ self._settings['mul_symbol'] try: self._settings['mul_symbol_latex_numbers'] = \ mul_symbol_table[self._settings['mul_symbol'] or 'dot'] except KeyError: if (self._settings['mul_symbol'].strip() in ['', ' ', '\\', '\\,', '\\:', '\\;', '\\quad']): self._settings['mul_symbol_latex_numbers'] = \ mul_symbol_table['dot'] else: self._settings['mul_symbol_latex_numbers'] = \ self._settings['mul_symbol'] self._delim_dict = {'(': ')', '[': ']'} def parenthesize(self, item, level, strict=False): prec_val = precedence_traditional(item) if (prec_val < level) or ((not strict) and prec_val <= level): return r"\left(%s\right)" % self._print(item) else: return self._print(item) def doprint(self, expr): tex = Printer.doprint(self, expr) if self._settings['mode'] == 'plain': return tex elif self._settings['mode'] == 'inline': return r"$%s$" % tex elif self._settings['itex']: return r"$$%s$$" % tex else: env_str = self._settings['mode'] return r"\begin{%s}%s\end{%s}" % (env_str, tex, env_str) def _needs_brackets(self, expr): """ Returns True if the expression needs to be wrapped in brackets when printed, False otherwise. For example: a + b => True; a => False; 10 => False; -10 => True. """ return not ((expr.is_Integer and expr.is_nonnegative) or (expr.is_Atom and (expr is not S.NegativeOne and expr.is_Rational is False))) def _needs_function_brackets(self, expr): """ Returns True if the expression needs to be wrapped in brackets when passed as an argument to a function, False otherwise. This is a more liberal version of _needs_brackets, in that many expressions which need to be wrapped in brackets when added/subtracted/raised to a power do not need them when passed to a function. Such an example is a*b. """ if not self._needs_brackets(expr): return False else: # Muls of the form a*b*c... can be folded if expr.is_Mul and not self._mul_is_clean(expr): return True # Pows which don't need brackets can be folded elif expr.is_Pow and not self._pow_is_clean(expr): return True # Add and Function always need brackets elif expr.is_Add or expr.is_Function: return True else: return False def _needs_mul_brackets(self, expr, first=False, last=False): """ Returns True if the expression needs to be wrapped in brackets when printed as part of a Mul, False otherwise. This is True for Add, but also for some container objects that would not need brackets when appearing last in a Mul, e.g. an Integral. ``last=True`` specifies that this expr is the last to appear in a Mul. ``first=True`` specifies that this expr is the first to appear in a Mul. """ from sympy import Integral, Piecewise, Product, Sum if expr.is_Mul: if not first and _coeff_isneg(expr): return True elif precedence_traditional(expr) < PRECEDENCE["Mul"]: return True elif expr.is_Relational: return True if expr.is_Piecewise: return True if any([expr.has(x) for x in (Mod,)]): return True if (not last and any([expr.has(x) for x in (Integral, Product, Sum)])): return True return False def _needs_add_brackets(self, expr): """ Returns True if the expression needs to be wrapped in brackets when printed as part of an Add, False otherwise. This is False for most things. """ if expr.is_Relational: return True if any([expr.has(x) for x in (Mod,)]): return True if expr.is_Add: return True return False def _mul_is_clean(self, expr): for arg in expr.args: if arg.is_Function: return False return True def _pow_is_clean(self, expr): return not self._needs_brackets(expr.base) def _do_exponent(self, expr, exp): if exp is not None: return r"\left(%s\right)^{%s}" % (expr, exp) else: return expr def _print_Basic(self, expr): l = [self._print(o) for o in expr.args] return self._deal_with_super_sub(expr.__class__.__name__) + r"\left(%s\right)" % ", ".join(l) def _print_bool(self, e): return r"\mathrm{%s}" % e _print_BooleanTrue = _print_bool _print_BooleanFalse = _print_bool def _print_NoneType(self, e): return r"\mathrm{%s}" % e def _print_Add(self, expr, order=None): if self.order == 'none': terms = list(expr.args) else: terms = self._as_ordered_terms(expr, order=order) tex = "" for i, term in enumerate(terms): if i == 0: pass elif _coeff_isneg(term): tex += " - " term = -term else: tex += " + " term_tex = self._print(term) if self._needs_add_brackets(term): term_tex = r"\left(%s\right)" % term_tex tex += term_tex return tex def _print_Cycle(self, expr): from sympy.combinatorics.permutations import Permutation if expr.size == 0: return r"\left( \right)" expr = Permutation(expr) expr_perm = expr.cyclic_form siz = expr.size if expr.array_form[-1] == siz - 1: expr_perm = expr_perm + [[siz - 1]] term_tex = '' for i in expr_perm: term_tex += str(i).replace(',', r"\;") term_tex = term_tex.replace('[', r"\left( ") term_tex = term_tex.replace(']', r"\right)") return term_tex _print_Permutation = _print_Cycle def _print_Float(self, expr): # Based off of that in StrPrinter dps = prec_to_dps(expr._prec) str_real = mlib.to_str(expr._mpf_, dps, strip_zeros=True) # Must always have a mul symbol (as 2.5 10^{20} just looks odd) # thus we use the number separator separator = self._settings['mul_symbol_latex_numbers'] if 'e' in str_real: (mant, exp) = str_real.split('e') if exp[0] == '+': exp = exp[1:] return r"%s%s10^{%s}" % (mant, separator, exp) elif str_real == "+inf": return r"\infty" elif str_real == "-inf": return r"- \infty" else: return str_real def _print_Cross(self, expr): vec1 = expr._expr1 vec2 = expr._expr2 return r"%s \times %s" % (self.parenthesize(vec1, PRECEDENCE['Mul']), self.parenthesize(vec2, PRECEDENCE['Mul'])) def _print_Curl(self, expr): vec = expr._expr return r"\nabla\times %s" % self.parenthesize(vec, PRECEDENCE['Mul']) def _print_Divergence(self, expr): vec = expr._expr return r"\nabla\cdot %s" % self.parenthesize(vec, PRECEDENCE['Mul']) def _print_Dot(self, expr): vec1 = expr._expr1 vec2 = expr._expr2 return r"%s \cdot %s" % (self.parenthesize(vec1, PRECEDENCE['Mul']), self.parenthesize(vec2, PRECEDENCE['Mul'])) def _print_Gradient(self, expr): func = expr._expr return r"\nabla\cdot %s" % self.parenthesize(func, PRECEDENCE['Mul']) def _print_Mul(self, expr): from sympy.core.power import Pow from sympy.physics.units import Quantity include_parens = False if _coeff_isneg(expr): expr = -expr tex = "- " if expr.is_Add: tex += "(" include_parens = True else: tex = "" from sympy.simplify import fraction numer, denom = fraction(expr, exact=True) separator = self._settings['mul_symbol_latex'] numbersep = self._settings['mul_symbol_latex_numbers'] def convert(expr): if not expr.is_Mul: return str(self._print(expr)) else: _tex = last_term_tex = "" if self.order not in ('old', 'none'): args = expr.as_ordered_factors() else: args = list(expr.args) # If quantities are present append them at the back args = sorted(args, key=lambda x: isinstance(x, Quantity) or (isinstance(x, Pow) and isinstance(x.base, Quantity))) for i, term in enumerate(args): term_tex = self._print(term) if self._needs_mul_brackets(term, first=(i == 0), last=(i == len(args) - 1)): term_tex = r"\left(%s\right)" % term_tex if _between_two_numbers_p[0].search(last_term_tex) and \ _between_two_numbers_p[1].match(term_tex): # between two numbers _tex += numbersep elif _tex: _tex += separator _tex += term_tex last_term_tex = term_tex return _tex if denom is S.One and Pow(1, -1, evaluate=False) not in expr.args: # use the original expression here, since fraction() may have # altered it when producing numer and denom tex += convert(expr) else: snumer = convert(numer) sdenom = convert(denom) ldenom = len(sdenom.split()) ratio = self._settings['long_frac_ratio'] if self._settings['fold_short_frac'] \ and ldenom <= 2 and not "^" in sdenom: # handle short fractions if self._needs_mul_brackets(numer, last=False): tex += r"\left(%s\right) / %s" % (snumer, sdenom) else: tex += r"%s / %s" % (snumer, sdenom) elif ratio is not None and \ len(snumer.split()) > ratio*ldenom: # handle long fractions if self._needs_mul_brackets(numer, last=True): tex += r"\frac{1}{%s}%s\left(%s\right)" \ % (sdenom, separator, snumer) elif numer.is_Mul: # split a long numerator a = S.One b = S.One for x in numer.args: if self._needs_mul_brackets(x, last=False) or \ len(convert(a*x).split()) > ratio*ldenom or \ (b.is_commutative is x.is_commutative is False): b *= x else: a *= x if self._needs_mul_brackets(b, last=True): tex += r"\frac{%s}{%s}%s\left(%s\right)" \ % (convert(a), sdenom, separator, convert(b)) else: tex += r"\frac{%s}{%s}%s%s" \ % (convert(a), sdenom, separator, convert(b)) else: tex += r"\frac{1}{%s}%s%s" % (sdenom, separator, snumer) else: tex += r"\frac{%s}{%s}" % (snumer, sdenom) if include_parens: tex += ")" return tex def _print_Pow(self, expr): # Treat x**Rational(1,n) as special case if expr.exp.is_Rational and abs(expr.exp.p) == 1 and expr.exp.q != 1: base = self._print(expr.base) expq = expr.exp.q if expq == 2: tex = r"\sqrt{%s}" % base elif self._settings['itex']: tex = r"\root{%d}{%s}" % (expq, base) else: tex = r"\sqrt[%d]{%s}" % (expq, base) if expr.exp.is_negative: return r"\frac{1}{%s}" % tex else: return tex elif self._settings['fold_frac_powers'] \ and expr.exp.is_Rational \ and expr.exp.q != 1: base, p, q = self.parenthesize(expr.base, PRECEDENCE['Pow']), expr.exp.p, expr.exp.q # issue #12886: add parentheses for superscripts raised to powers if '^' in base and expr.base.is_Symbol: base = r"\left(%s\right)" % base if expr.base.is_Function: return self._print(expr.base, exp="%s/%s" % (p, q)) return r"%s^{%s/%s}" % (base, p, q) elif expr.exp.is_Rational and expr.exp.is_negative and expr.base.is_commutative: # special case for 1^(-x), issue 9216 if expr.base == 1: return r"%s^{%s}" % (expr.base, expr.exp) # things like 1/x return self._print_Mul(expr) else: if expr.base.is_Function: return self._print(expr.base, exp=self._print(expr.exp)) else: tex = r"%s^{%s}" exp = self._print(expr.exp) # issue #12886: add parentheses around superscripts raised to powers base = self.parenthesize(expr.base, PRECEDENCE['Pow']) if '^' in base and expr.base.is_Symbol: base = r"\left(%s\right)" % base elif isinstance(expr.base, Derivative ) and base.startswith(r'\left(' ) and re.match(r'\\left\(\\d?d?dot', base ) and base.endswith(r'\right)'): # don't use parentheses around dotted derivative base = base[6: -7] # remove outermost added parens return tex % (base, exp) def _print_UnevaluatedExpr(self, expr): return self._print(expr.args[0]) def _print_Sum(self, expr): if len(expr.limits) == 1: tex = r"\sum_{%s=%s}^{%s} " % \ tuple([ self._print(i) for i in expr.limits[0] ]) else: def _format_ineq(l): return r"%s \leq %s \leq %s" % \ tuple([self._print(s) for s in (l[1], l[0], l[2])]) tex = r"\sum_{\substack{%s}} " % \ str.join('\\\\', [ _format_ineq(l) for l in expr.limits ]) if isinstance(expr.function, Add): tex += r"\left(%s\right)" % self._print(expr.function) else: tex += self._print(expr.function) return tex def _print_Product(self, expr): if len(expr.limits) == 1: tex = r"\prod_{%s=%s}^{%s} " % \ tuple([ self._print(i) for i in expr.limits[0] ]) else: def _format_ineq(l): return r"%s \leq %s \leq %s" % \ tuple([self._print(s) for s in (l[1], l[0], l[2])]) tex = r"\prod_{\substack{%s}} " % \ str.join('\\\\', [ _format_ineq(l) for l in expr.limits ]) if isinstance(expr.function, Add): tex += r"\left(%s\right)" % self._print(expr.function) else: tex += self._print(expr.function) return tex def _print_BasisDependent(self, expr): from sympy.vector import Vector o1 = [] if expr == expr.zero: return expr.zero._latex_form if isinstance(expr, Vector): items = expr.separate().items() else: items = [(0, expr)] for system, vect in items: inneritems = list(vect.components.items()) inneritems.sort(key = lambda x:x[0].__str__()) for k, v in inneritems: if v == 1: o1.append(' + ' + k._latex_form) elif v == -1: o1.append(' - ' + k._latex_form) else: arg_str = '(' + LatexPrinter().doprint(v) + ')' o1.append(' + ' + arg_str + k._latex_form) outstr = (''.join(o1)) if outstr[1] != '-': outstr = outstr[3:] else: outstr = outstr[1:] return outstr def _print_Indexed(self, expr): tex_base = self._print(expr.base) tex = '{'+tex_base+'}'+'_{%s}' % ','.join( map(self._print, expr.indices)) return tex def _print_IndexedBase(self, expr): return self._print(expr.label) def _print_Derivative(self, expr): if requires_partial(expr): diff_symbol = r'\partial' else: diff_symbol = r'd' tex = "" dim = 0 for x, num in reversed(expr.variable_count): dim += num if num == 1: tex += r"%s %s" % (diff_symbol, self._print(x)) else: tex += r"%s %s^{%s}" % (diff_symbol, self._print(x), num) if dim == 1: tex = r"\frac{%s}{%s}" % (diff_symbol, tex) else: tex = r"\frac{%s^{%s}}{%s}" % (diff_symbol, dim, tex) return r"%s %s" % (tex, self.parenthesize(expr.expr, PRECEDENCE["Mul"], strict=True)) def _print_Subs(self, subs): expr, old, new = subs.args latex_expr = self._print(expr) latex_old = (self._print(e) for e in old) latex_new = (self._print(e) for e in new) latex_subs = r'\\ '.join( e[0] + '=' + e[1] for e in zip(latex_old, latex_new)) return r'\left. %s \right|_{\substack{ %s }}' % (latex_expr, latex_subs) def _print_Integral(self, expr): tex, symbols = "", [] # Only up to \iiiint exists if len(expr.limits) <= 4 and all(len(lim) == 1 for lim in expr.limits): # Use len(expr.limits)-1 so that syntax highlighters don't think # \" is an escaped quote tex = r"\i" + "i"*(len(expr.limits) - 1) + "nt" symbols = [r"\, d%s" % self._print(symbol[0]) for symbol in expr.limits] else: for lim in reversed(expr.limits): symbol = lim[0] tex += r"\int" if len(lim) > 1: if self._settings['mode'] != 'inline' \ and not self._settings['itex']: tex += r"\limits" if len(lim) == 3: tex += "_{%s}^{%s}" % (self._print(lim[1]), self._print(lim[2])) if len(lim) == 2: tex += "^{%s}" % (self._print(lim[1])) symbols.insert(0, r"\, d%s" % self._print(symbol)) return r"%s %s%s" % (tex, self.parenthesize(expr.function, PRECEDENCE["Mul"], strict=True), "".join(symbols)) def _print_Limit(self, expr): e, z, z0, dir = expr.args tex = r"\lim_{%s \to " % self._print(z) if str(dir) == '+-' or z0 in (S.Infinity, S.NegativeInfinity): tex += r"%s}" % self._print(z0) else: tex += r"%s^%s}" % (self._print(z0), self._print(dir)) if isinstance(e, AssocOp): return r"%s\left(%s\right)" % (tex, self._print(e)) else: return r"%s %s" % (tex, self._print(e)) def _hprint_Function(self, func): r''' Logic to decide how to render a function to latex - if it is a recognized latex name, use the appropriate latex command - if it is a single letter, just use that letter - if it is a longer name, then put \operatorname{} around it and be mindful of undercores in the name ''' func = self._deal_with_super_sub(func) if func in accepted_latex_functions: name = r"\%s" % func elif len(func) == 1 or func.startswith('\\'): name = func else: name = r"\operatorname{%s}" % func return name def _print_Function(self, expr, exp=None): r''' Render functions to LaTeX, handling functions that LaTeX knows about e.g., sin, cos, ... by using the proper LaTeX command (\sin, \cos, ...). For single-letter function names, render them as regular LaTeX math symbols. For multi-letter function names that LaTeX does not know about, (e.g., Li, sech) use \operatorname{} so that the function name is rendered in Roman font and LaTeX handles spacing properly. expr is the expression involving the function exp is an exponent ''' func = expr.func.__name__ if hasattr(self, '_print_' + func) and \ not isinstance(expr, AppliedUndef): return getattr(self, '_print_' + func)(expr, exp) else: args = [ str(self._print(arg)) for arg in expr.args ] # How inverse trig functions should be displayed, formats are: # abbreviated: asin, full: arcsin, power: sin^-1 inv_trig_style = self._settings['inv_trig_style'] # If we are dealing with a power-style inverse trig function inv_trig_power_case = False # If it is applicable to fold the argument brackets can_fold_brackets = self._settings['fold_func_brackets'] and \ len(args) == 1 and \ not self._needs_function_brackets(expr.args[0]) inv_trig_table = ["asin", "acos", "atan", "acsc", "asec", "acot"] # If the function is an inverse trig function, handle the style if func in inv_trig_table: if inv_trig_style == "abbreviated": func = func elif inv_trig_style == "full": func = "arc" + func[1:] elif inv_trig_style == "power": func = func[1:] inv_trig_power_case = True # Can never fold brackets if we're raised to a power if exp is not None: can_fold_brackets = False if inv_trig_power_case: if func in accepted_latex_functions: name = r"\%s^{-1}" % func else: name = r"\operatorname{%s}^{-1}" % func elif exp is not None: name = r'%s^{%s}' % (self._hprint_Function(func), exp) else: name = self._hprint_Function(func) if can_fold_brackets: if func in accepted_latex_functions: # Wrap argument safely to avoid parse-time conflicts # with the function name itself name += r" {%s}" else: name += r"%s" else: name += r"{\left(%s \right)}" if inv_trig_power_case and exp is not None: name += r"^{%s}" % exp return name % ",".join(args) def _print_UndefinedFunction(self, expr): return self._hprint_Function(str(expr)) @property def _special_function_classes(self): from sympy.functions.special.tensor_functions import KroneckerDelta from sympy.functions.special.gamma_functions import gamma, lowergamma from sympy.functions.special.beta_functions import beta from sympy.functions.special.delta_functions import DiracDelta from sympy.functions.special.error_functions import Chi return {KroneckerDelta: r'\delta', gamma: r'\Gamma', lowergamma: r'\gamma', beta: r'\operatorname{B}', DiracDelta: r'\delta', Chi: r'\operatorname{Chi}'} def _print_FunctionClass(self, expr): for cls in self._special_function_classes: if issubclass(expr, cls) and expr.__name__ == cls.__name__: return self._special_function_classes[cls] return self._hprint_Function(str(expr)) def _print_Lambda(self, expr): symbols, expr = expr.args if len(symbols) == 1: symbols = self._print(symbols[0]) else: symbols = self._print(tuple(symbols)) args = (symbols, self._print(expr)) tex = r"\left( %s \mapsto %s \right)" % (symbols, self._print(expr)) return tex def _hprint_variadic_function(self, expr, exp=None): args = sorted(expr.args, key=default_sort_key) texargs = [r"%s" % self._print(symbol) for symbol in args] tex = r"\%s\left(%s\right)" % (self._print((str(expr.func)).lower()), ", ".join(texargs)) if exp is not None: return r"%s^{%s}" % (tex, exp) else: return tex _print_Min = _print_Max = _hprint_variadic_function def _print_floor(self, expr, exp=None): tex = r"\left\lfloor{%s}\right\rfloor" % self._print(expr.args[0]) if exp is not None: return r"%s^{%s}" % (tex, exp) else: return tex def _print_ceiling(self, expr, exp=None): tex = r"\left\lceil{%s}\right\rceil" % self._print(expr.args[0]) if exp is not None: return r"%s^{%s}" % (tex, exp) else: return tex def _print_log(self, expr, exp=None): if not self._settings["ln_notation"]: tex = r"\log{\left(%s \right)}" % self._print(expr.args[0]) else: tex = r"\ln{\left(%s \right)}" % self._print(expr.args[0]) if exp is not None: return r"%s^{%s}" % (tex, exp) else: return tex def _print_Abs(self, expr, exp=None): tex = r"\left|{%s}\right|" % self._print(expr.args[0]) if exp is not None: return r"%s^{%s}" % (tex, exp) else: return tex _print_Determinant = _print_Abs def _print_re(self, expr, exp=None): tex = r"\Re{%s}" % self.parenthesize(expr.args[0], PRECEDENCE['Atom']) return self._do_exponent(tex, exp) def _print_im(self, expr, exp=None): tex = r"\Im{%s}" % self.parenthesize(expr.args[0], PRECEDENCE['Func']) return self._do_exponent(tex, exp) def _print_Not(self, e): from sympy import Equivalent, Implies if isinstance(e.args[0], Equivalent): return self._print_Equivalent(e.args[0], r"\not\Leftrightarrow") if isinstance(e.args[0], Implies): return self._print_Implies(e.args[0], r"\not\Rightarrow") if (e.args[0].is_Boolean): return r"\neg (%s)" % self._print(e.args[0]) else: return r"\neg %s" % self._print(e.args[0]) def _print_LogOp(self, args, char): arg = args[0] if arg.is_Boolean and not arg.is_Not: tex = r"\left(%s\right)" % self._print(arg) else: tex = r"%s" % self._print(arg) for arg in args[1:]: if arg.is_Boolean and not arg.is_Not: tex += r" %s \left(%s\right)" % (char, self._print(arg)) else: tex += r" %s %s" % (char, self._print(arg)) return tex def _print_And(self, e): args = sorted(e.args, key=default_sort_key) return self._print_LogOp(args, r"\wedge") def _print_Or(self, e): args = sorted(e.args, key=default_sort_key) return self._print_LogOp(args, r"\vee") def _print_Xor(self, e): args = sorted(e.args, key=default_sort_key) return self._print_LogOp(args, r"\veebar") def _print_Implies(self, e, altchar=None): return self._print_LogOp(e.args, altchar or r"\Rightarrow") def _print_Equivalent(self, e, altchar=None): args = sorted(e.args, key=default_sort_key) return self._print_LogOp(args, altchar or r"\Leftrightarrow") def _print_conjugate(self, expr, exp=None): tex = r"\overline{%s}" % self._print(expr.args[0]) if exp is not None: return r"%s^{%s}" % (tex, exp) else: return tex def _print_polar_lift(self, expr, exp=None): func = r"\operatorname{polar\_lift}" arg = r"{\left(%s \right)}" % self._print(expr.args[0]) if exp is not None: return r"%s^{%s}%s" % (func, exp, arg) else: return r"%s%s" % (func, arg) def _print_ExpBase(self, expr, exp=None): # TODO should exp_polar be printed differently? # what about exp_polar(0), exp_polar(1)? tex = r"e^{%s}" % self._print(expr.args[0]) return self._do_exponent(tex, exp) def _print_elliptic_k(self, expr, exp=None): tex = r"\left(%s\right)" % self._print(expr.args[0]) if exp is not None: return r"K^{%s}%s" % (exp, tex) else: return r"K%s" % tex def _print_elliptic_f(self, expr, exp=None): tex = r"\left(%s\middle| %s\right)" % \ (self._print(expr.args[0]), self._print(expr.args[1])) if exp is not None: return r"F^{%s}%s" % (exp, tex) else: return r"F%s" % tex def _print_elliptic_e(self, expr, exp=None): if len(expr.args) == 2: tex = r"\left(%s\middle| %s\right)" % \ (self._print(expr.args[0]), self._print(expr.args[1])) else: tex = r"\left(%s\right)" % self._print(expr.args[0]) if exp is not None: return r"E^{%s}%s" % (exp, tex) else: return r"E%s" % tex def _print_elliptic_pi(self, expr, exp=None): if len(expr.args) == 3: tex = r"\left(%s; %s\middle| %s\right)" % \ (self._print(expr.args[0]), self._print(expr.args[1]), \ self._print(expr.args[2])) else: tex = r"\left(%s\middle| %s\right)" % \ (self._print(expr.args[0]), self._print(expr.args[1])) if exp is not None: return r"\Pi^{%s}%s" % (exp, tex) else: return r"\Pi%s" % tex def _print_beta(self, expr, exp=None): tex = r"\left(%s, %s\right)" % (self._print(expr.args[0]), self._print(expr.args[1])) if exp is not None: return r"\operatorname{B}^{%s}%s" % (exp, tex) else: return r"\operatorname{B}%s" % tex def _print_uppergamma(self, expr, exp=None): tex = r"\left(%s, %s\right)" % (self._print(expr.args[0]), self._print(expr.args[1])) if exp is not None: return r"\Gamma^{%s}%s" % (exp, tex) else: return r"\Gamma%s" % tex def _print_lowergamma(self, expr, exp=None): tex = r"\left(%s, %s\right)" % (self._print(expr.args[0]), self._print(expr.args[1])) if exp is not None: return r"\gamma^{%s}%s" % (exp, tex) else: return r"\gamma%s" % tex def _hprint_one_arg_func(self, expr, exp=None): tex = r"\left(%s\right)" % self._print(expr.args[0]) if exp is not None: return r"%s^{%s}%s" % (self._print(expr.func), exp, tex) else: return r"%s%s" % (self._print(expr.func), tex) _print_gamma = _hprint_one_arg_func def _print_Chi(self, expr, exp=None): tex = r"\left(%s\right)" % self._print(expr.args[0]) if exp is not None: return r"\operatorname{Chi}^{%s}%s" % (exp, tex) else: return r"\operatorname{Chi}%s" % tex def _print_expint(self, expr, exp=None): tex = r"\left(%s\right)" % self._print(expr.args[1]) nu = self._print(expr.args[0]) if exp is not None: return r"\operatorname{E}_{%s}^{%s}%s" % (nu, exp, tex) else: return r"\operatorname{E}_{%s}%s" % (nu, tex) def _print_fresnels(self, expr, exp=None): tex = r"\left(%s\right)" % self._print(expr.args[0]) if exp is not None: return r"S^{%s}%s" % (exp, tex) else: return r"S%s" % tex def _print_fresnelc(self, expr, exp=None): tex = r"\left(%s\right)" % self._print(expr.args[0]) if exp is not None: return r"C^{%s}%s" % (exp, tex) else: return r"C%s" % tex def _print_subfactorial(self, expr, exp=None): tex = r"!%s" % self.parenthesize(expr.args[0], PRECEDENCE["Func"]) if exp is not None: return r"%s^{%s}" % (tex, exp) else: return tex def _print_factorial(self, expr, exp=None): tex = r"%s!" % self.parenthesize(expr.args[0], PRECEDENCE["Func"]) if exp is not None: return r"%s^{%s}" % (tex, exp) else: return tex def _print_factorial2(self, expr, exp=None): tex = r"%s!!" % self.parenthesize(expr.args[0], PRECEDENCE["Func"]) if exp is not None: return r"%s^{%s}" % (tex, exp) else: return tex def _print_binomial(self, expr, exp=None): tex = r"{\binom{%s}{%s}}" % (self._print(expr.args[0]), self._print(expr.args[1])) if exp is not None: return r"%s^{%s}" % (tex, exp) else: return tex def _print_RisingFactorial(self, expr, exp=None): n, k = expr.args base = r"%s" % self.parenthesize(n, PRECEDENCE['Func']) tex = r"{%s}^{\left(%s\right)}" % (base, self._print(k)) return self._do_exponent(tex, exp) def _print_FallingFactorial(self, expr, exp=None): n, k = expr.args sub = r"%s" % self.parenthesize(k, PRECEDENCE['Func']) tex = r"{\left(%s\right)}_{%s}" % (self._print(n), sub) return self._do_exponent(tex, exp) def _hprint_BesselBase(self, expr, exp, sym): tex = r"%s" % (sym) need_exp = False if exp is not None: if tex.find('^') == -1: tex = r"%s^{%s}" % (tex, self._print(exp)) else: need_exp = True tex = r"%s_{%s}\left(%s\right)" % (tex, self._print(expr.order), self._print(expr.argument)) if need_exp: tex = self._do_exponent(tex, exp) return tex def _hprint_vec(self, vec): if len(vec) == 0: return "" s = "" for i in vec[:-1]: s += "%s, " % self._print(i) s += self._print(vec[-1]) return s def _print_besselj(self, expr, exp=None): return self._hprint_BesselBase(expr, exp, 'J') def _print_besseli(self, expr, exp=None): return self._hprint_BesselBase(expr, exp, 'I') def _print_besselk(self, expr, exp=None): return self._hprint_BesselBase(expr, exp, 'K') def _print_bessely(self, expr, exp=None): return self._hprint_BesselBase(expr, exp, 'Y') def _print_yn(self, expr, exp=None): return self._hprint_BesselBase(expr, exp, 'y') def _print_jn(self, expr, exp=None): return self._hprint_BesselBase(expr, exp, 'j') def _print_hankel1(self, expr, exp=None): return self._hprint_BesselBase(expr, exp, 'H^{(1)}') def _print_hankel2(self, expr, exp=None): return self._hprint_BesselBase(expr, exp, 'H^{(2)}') def _print_hn1(self, expr, exp=None): return self._hprint_BesselBase(expr, exp, 'h^{(1)}') def _print_hn2(self, expr, exp=None): return self._hprint_BesselBase(expr, exp, 'h^{(2)}') def _hprint_airy(self, expr, exp=None, notation=""): tex = r"\left(%s\right)" % self._print(expr.args[0]) if exp is not None: return r"%s^{%s}%s" % (notation, exp, tex) else: return r"%s%s" % (notation, tex) def _hprint_airy_prime(self, expr, exp=None, notation=""): tex = r"\left(%s\right)" % self._print(expr.args[0]) if exp is not None: return r"{%s^\prime}^{%s}%s" % (notation, exp, tex) else: return r"%s^\prime%s" % (notation, tex) def _print_airyai(self, expr, exp=None): return self._hprint_airy(expr, exp, 'Ai') def _print_airybi(self, expr, exp=None): return self._hprint_airy(expr, exp, 'Bi') def _print_airyaiprime(self, expr, exp=None): return self._hprint_airy_prime(expr, exp, 'Ai') def _print_airybiprime(self, expr, exp=None): return self._hprint_airy_prime(expr, exp, 'Bi') def _print_hyper(self, expr, exp=None): tex = r"{{}_{%s}F_{%s}\left(\begin{matrix} %s \\ %s \end{matrix}" \ r"\middle| {%s} \right)}" % \ (self._print(len(expr.ap)), self._print(len(expr.bq)), self._hprint_vec(expr.ap), self._hprint_vec(expr.bq), self._print(expr.argument)) if exp is not None: tex = r"{%s}^{%s}" % (tex, self._print(exp)) return tex def _print_meijerg(self, expr, exp=None): tex = r"{G_{%s, %s}^{%s, %s}\left(\begin{matrix} %s & %s \\" \ r"%s & %s \end{matrix} \middle| {%s} \right)}" % \ (self._print(len(expr.ap)), self._print(len(expr.bq)), self._print(len(expr.bm)), self._print(len(expr.an)), self._hprint_vec(expr.an), self._hprint_vec(expr.aother), self._hprint_vec(expr.bm), self._hprint_vec(expr.bother), self._print(expr.argument)) if exp is not None: tex = r"{%s}^{%s}" % (tex, self._print(exp)) return tex def _print_dirichlet_eta(self, expr, exp=None): tex = r"\left(%s\right)" % self._print(expr.args[0]) if exp is not None: return r"\eta^{%s}%s" % (self._print(exp), tex) return r"\eta%s" % tex def _print_zeta(self, expr, exp=None): if len(expr.args) == 2: tex = r"\left(%s, %s\right)" % tuple(map(self._print, expr.args)) else: tex = r"\left(%s\right)" % self._print(expr.args[0]) if exp is not None: return r"\zeta^{%s}%s" % (self._print(exp), tex) return r"\zeta%s" % tex def _print_lerchphi(self, expr, exp=None): tex = r"\left(%s, %s, %s\right)" % tuple(map(self._print, expr.args)) if exp is None: return r"\Phi%s" % tex return r"\Phi^{%s}%s" % (self._print(exp), tex) def _print_polylog(self, expr, exp=None): s, z = map(self._print, expr.args) tex = r"\left(%s\right)" % z if exp is None: return r"\operatorname{Li}_{%s}%s" % (s, tex) return r"\operatorname{Li}_{%s}^{%s}%s" % (s, self._print(exp), tex) def _print_jacobi(self, expr, exp=None): n, a, b, x = map(self._print, expr.args) tex = r"P_{%s}^{\left(%s,%s\right)}\left(%s\right)" % (n, a, b, x) if exp is not None: tex = r"\left(" + tex + r"\right)^{%s}" % (self._print(exp)) return tex def _print_gegenbauer(self, expr, exp=None): n, a, x = map(self._print, expr.args) tex = r"C_{%s}^{\left(%s\right)}\left(%s\right)" % (n, a, x) if exp is not None: tex = r"\left(" + tex + r"\right)^{%s}" % (self._print(exp)) return tex def _print_chebyshevt(self, expr, exp=None): n, x = map(self._print, expr.args) tex = r"T_{%s}\left(%s\right)" % (n, x) if exp is not None: tex = r"\left(" + tex + r"\right)^{%s}" % (self._print(exp)) return tex def _print_chebyshevu(self, expr, exp=None): n, x = map(self._print, expr.args) tex = r"U_{%s}\left(%s\right)" % (n, x) if exp is not None: tex = r"\left(" + tex + r"\right)^{%s}" % (self._print(exp)) return tex def _print_legendre(self, expr, exp=None): n, x = map(self._print, expr.args) tex = r"P_{%s}\left(%s\right)" % (n, x) if exp is not None: tex = r"\left(" + tex + r"\right)^{%s}" % (self._print(exp)) return tex def _print_assoc_legendre(self, expr, exp=None): n, a, x = map(self._print, expr.args) tex = r"P_{%s}^{\left(%s\right)}\left(%s\right)" % (n, a, x) if exp is not None: tex = r"\left(" + tex + r"\right)^{%s}" % (self._print(exp)) return tex def _print_hermite(self, expr, exp=None): n, x = map(self._print, expr.args) tex = r"H_{%s}\left(%s\right)" % (n, x) if exp is not None: tex = r"\left(" + tex + r"\right)^{%s}" % (self._print(exp)) return tex def _print_laguerre(self, expr, exp=None): n, x = map(self._print, expr.args) tex = r"L_{%s}\left(%s\right)" % (n, x) if exp is not None: tex = r"\left(" + tex + r"\right)^{%s}" % (self._print(exp)) return tex def _print_assoc_laguerre(self, expr, exp=None): n, a, x = map(self._print, expr.args) tex = r"L_{%s}^{\left(%s\right)}\left(%s\right)" % (n, a, x) if exp is not None: tex = r"\left(" + tex + r"\right)^{%s}" % (self._print(exp)) return tex def _print_Ynm(self, expr, exp=None): n, m, theta, phi = map(self._print, expr.args) tex = r"Y_{%s}^{%s}\left(%s,%s\right)" % (n, m, theta, phi) if exp is not None: tex = r"\left(" + tex + r"\right)^{%s}" % (self._print(exp)) return tex def _print_Znm(self, expr, exp=None): n, m, theta, phi = map(self._print, expr.args) tex = r"Z_{%s}^{%s}\left(%s,%s\right)" % (n, m, theta, phi) if exp is not None: tex = r"\left(" + tex + r"\right)^{%s}" % (self._print(exp)) return tex def _print_Rational(self, expr): if expr.q != 1: sign = "" p = expr.p if expr.p < 0: sign = "- " p = -p if self._settings['fold_short_frac']: return r"%s%d / %d" % (sign, p, expr.q) return r"%s\frac{%d}{%d}" % (sign, p, expr.q) else: return self._print(expr.p) def _print_Order(self, expr): s = self._print(expr.expr) if expr.point and any(p != S.Zero for p in expr.point) or \ len(expr.variables) > 1: s += '; ' if len(expr.variables) > 1: s += self._print(expr.variables) elif len(expr.variables): s += self._print(expr.variables[0]) s += r'\rightarrow ' if len(expr.point) > 1: s += self._print(expr.point) else: s += self._print(expr.point[0]) return r"O\left(%s\right)" % s def _print_Symbol(self, expr): if expr in self._settings['symbol_names']: return self._settings['symbol_names'][expr] return self._deal_with_super_sub(expr.name) if \ '\\' not in expr.name else expr.name _print_RandomSymbol = _print_Symbol _print_MatrixSymbol = _print_Symbol def _deal_with_super_sub(self, string): if '{' in string: return string name, supers, subs = split_super_sub(string) name = translate(name) supers = [translate(sup) for sup in supers] subs = [translate(sub) for sub in subs] # glue all items together: if len(supers) > 0: name += "^{%s}" % " ".join(supers) if len(subs) > 0: name += "_{%s}" % " ".join(subs) return name def _print_Relational(self, expr): if self._settings['itex']: gt = r"\gt" lt = r"\lt" else: gt = ">" lt = "<" charmap = { "==": "=", ">": gt, "<": lt, ">=": r"\geq", "<=": r"\leq", "!=": r"\neq", } return "%s %s %s" % (self._print(expr.lhs), charmap[expr.rel_op], self._print(expr.rhs)) def _print_Piecewise(self, expr): ecpairs = [r"%s & \text{for}\: %s" % (self._print(e), self._print(c)) for e, c in expr.args[:-1]] if expr.args[-1].cond == true: ecpairs.append(r"%s & \text{otherwise}" % self._print(expr.args[-1].expr)) else: ecpairs.append(r"%s & \text{for}\: %s" % (self._print(expr.args[-1].expr), self._print(expr.args[-1].cond))) tex = r"\begin{cases} %s \end{cases}" return tex % r" \\".join(ecpairs) def _print_MatrixBase(self, expr): lines = [] for line in range(expr.rows): # horrible, should be 'rows' lines.append(" & ".join([ self._print(i) for i in expr[line, :] ])) mat_str = self._settings['mat_str'] if mat_str is None: if self._settings['mode'] == 'inline': mat_str = 'smallmatrix' else: if (expr.cols <= 10) is True: mat_str = 'matrix' else: mat_str = 'array' out_str = r'\begin{%MATSTR%}%s\end{%MATSTR%}' out_str = out_str.replace('%MATSTR%', mat_str) if mat_str == 'array': out_str = out_str.replace('%s', '{' + 'c'*expr.cols + '}%s') if self._settings['mat_delim']: left_delim = self._settings['mat_delim'] right_delim = self._delim_dict[left_delim] out_str = r'\left' + left_delim + out_str + \ r'\right' + right_delim return out_str % r"\\".join(lines) _print_ImmutableMatrix = _print_ImmutableDenseMatrix \ = _print_Matrix \ = _print_MatrixBase def _print_MatrixElement(self, expr): return self.parenthesize(expr.parent, PRECEDENCE["Atom"], strict=True) \ + '_{%s, %s}' % ( self._print(expr.i), self._print(expr.j) ) def _print_MatrixSlice(self, expr): def latexslice(x): x = list(x) if x[2] == 1: del x[2] if x[1] == x[0] + 1: del x[1] if x[0] == 0: x[0] = '' return ':'.join(map(self._print, x)) return (self._print(expr.parent) + r'\left[' + latexslice(expr.rowslice) + ', ' + latexslice(expr.colslice) + r'\right]') def _print_BlockMatrix(self, expr): return self._print(expr.blocks) def _print_Transpose(self, expr): mat = expr.arg from sympy.matrices import MatrixSymbol if not isinstance(mat, MatrixSymbol): return r"\left(%s\right)^T" % self._print(mat) else: return "%s^T" % self._print(mat) def _print_Trace(self, expr): mat = expr.arg return r"\mathrm{tr}\left(%s \right)" % self._print(mat) def _print_Adjoint(self, expr): mat = expr.arg from sympy.matrices import MatrixSymbol if not isinstance(mat, MatrixSymbol): return r"\left(%s\right)^\dagger" % self._print(mat) else: return r"%s^\dagger" % self._print(mat) def _print_MatMul(self, expr): from sympy import Add, MatAdd, HadamardProduct, MatMul, Mul parens = lambda x: self.parenthesize(x, precedence_traditional(expr), False) args = expr.args if isinstance(args[0], Mul): args = args[0].as_ordered_factors() + list(args[1:]) else: args = list(args) if isinstance(expr, MatMul) and _coeff_isneg(expr): if args[0] == -1: args = args[1:] else: args[0] = -args[0] return '- ' + ' '.join(map(parens, args)) else: return ' '.join(map(parens, args)) def _print_Mod(self, expr, exp=None): if exp is not None: return r'\left(%s\bmod{%s}\right)^{%s}' % (self.parenthesize(expr.args[0], PRECEDENCE['Mul'], strict=True), self._print(expr.args[1]), self._print(exp)) return r'%s\bmod{%s}' % (self.parenthesize(expr.args[0], PRECEDENCE['Mul'], strict=True), self._print(expr.args[1])) def _print_HadamardProduct(self, expr): from sympy import Add, MatAdd, MatMul def parens(x): if isinstance(x, (Add, MatAdd, MatMul)): return r"\left(%s\right)" % self._print(x) return self._print(x) return r' \circ '.join(map(parens, expr.args)) def _print_KroneckerProduct(self, expr): from sympy import Add, MatAdd, MatMul def parens(x): if isinstance(x, (Add, MatAdd, MatMul)): return r"\left(%s\right)" % self._print(x) return self._print(x) return r' \otimes '.join(map(parens, expr.args)) def _print_MatPow(self, expr): base, exp = expr.base, expr.exp from sympy.matrices import MatrixSymbol if not isinstance(base, MatrixSymbol): return r"\left(%s\right)^{%s}" % (self._print(base), self._print(exp)) else: return "%s^{%s}" % (self._print(base), self._print(exp)) def _print_ZeroMatrix(self, Z): return r"\mathbb{0}" def _print_Identity(self, I): return r"\mathbb{I}" def _print_NDimArray(self, expr): if expr.rank() == 0: return self._print(expr[()]) mat_str = self._settings['mat_str'] if mat_str is None: if self._settings['mode'] == 'inline': mat_str = 'smallmatrix' else: if (expr.rank() == 0) or (expr.shape[-1] <= 10): mat_str = 'matrix' else: mat_str = 'array' block_str = r'\begin{%MATSTR%}%s\end{%MATSTR%}' block_str = block_str.replace('%MATSTR%', mat_str) if self._settings['mat_delim']: left_delim = self._settings['mat_delim'] right_delim = self._delim_dict[left_delim] block_str = r'\left' + left_delim + block_str + \ r'\right' + right_delim if expr.rank() == 0: return block_str % "" level_str = [[]] + [[] for i in range(expr.rank())] shape_ranges = [list(range(i)) for i in expr.shape] for outer_i in itertools.product(*shape_ranges): level_str[-1].append(self._print(expr[outer_i])) even = True for back_outer_i in range(expr.rank()-1, -1, -1): if len(level_str[back_outer_i+1]) < expr.shape[back_outer_i]: break if even: level_str[back_outer_i].append(r" & ".join(level_str[back_outer_i+1])) else: level_str[back_outer_i].append(block_str % (r"\\".join(level_str[back_outer_i+1]))) if len(level_str[back_outer_i+1]) == 1: level_str[back_outer_i][-1] = r"\left[" + level_str[back_outer_i][-1] + r"\right]" even = not even level_str[back_outer_i+1] = [] out_str = level_str[0][0] if expr.rank() % 2 == 1: out_str = block_str % out_str return out_str _print_ImmutableDenseNDimArray = _print_NDimArray _print_ImmutableSparseNDimArray = _print_NDimArray _print_MutableDenseNDimArray = _print_NDimArray _print_MutableSparseNDimArray = _print_NDimArray def _printer_tensor_indices(self, name, indices, index_map={}): out_str = self._print(name) last_valence = None prev_map = None for index in indices: new_valence = index.is_up if ((index in index_map) or prev_map) and last_valence == new_valence: out_str += "," if last_valence != new_valence: if last_valence is not None: out_str += "}" if index.is_up: out_str += "{}^{" else: out_str += "{}_{" out_str += self._print(index.args[0]) if index in index_map: out_str += "=" out_str += self._print(index_map[index]) prev_map = True else: prev_map = False last_valence = new_valence if last_valence is not None: out_str += "}" return out_str def _print_Tensor(self, expr): name = expr.args[0].args[0] indices = expr.get_indices() return self._printer_tensor_indices(name, indices) def _print_TensorElement(self, expr): name = expr.expr.args[0].args[0] indices = expr.expr.get_indices() index_map = expr.index_map return self._printer_tensor_indices(name, indices, index_map) def _print_TensMul(self, expr): # prints expressions like "A(a)", "3*A(a)", "(1+x)*A(a)" sign, args = expr._get_args_for_traditional_printer() return sign + "".join( [self.parenthesize(arg, precedence(expr)) for arg in args] ) def _print_TensAdd(self, expr): a = [] args = expr.args for x in args: a.append(self.parenthesize(x, precedence(expr))) a.sort() s = ' + '.join(a) s = s.replace('+ -', '- ') return s def _print_TensorIndex(self, expr): return "{}%s{%s}" % ( "^" if expr.is_up else "_", self._print(expr.args[0]) ) return self._print(expr.args[0]) def _print_tuple(self, expr): return r"\left( %s\right)" % \ r", \quad ".join([ self._print(i) for i in expr ]) def _print_TensorProduct(self, expr): elements = [self._print(a) for a in expr.args] return r' \otimes '.join(elements) def _print_WedgeProduct(self, expr): elements = [self._print(a) for a in expr.args] return r' \wedge '.join(elements) def _print_Tuple(self, expr): return self._print_tuple(expr) def _print_list(self, expr): return r"\left[ %s\right]" % \ r", \quad ".join([ self._print(i) for i in expr ]) def _print_dict(self, d): keys = sorted(d.keys(), key=default_sort_key) items = [] for key in keys: val = d[key] items.append("%s : %s" % (self._print(key), self._print(val))) return r"\left\{ %s\right\}" % r", \quad ".join(items) def _print_Dict(self, expr): return self._print_dict(expr) def _print_DiracDelta(self, expr, exp=None): if len(expr.args) == 1 or expr.args[1] == 0: tex = r"\delta\left(%s\right)" % self._print(expr.args[0]) else: tex = r"\delta^{\left( %s \right)}\left( %s \right)" % ( self._print(expr.args[1]), self._print(expr.args[0])) if exp: tex = r"\left(%s\right)^{%s}" % (tex, exp) return tex def _print_SingularityFunction(self, expr): shift = self._print(expr.args[0] - expr.args[1]) power = self._print(expr.args[2]) tex = r"{\left\langle %s \right\rangle}^{%s}" % (shift, power) return tex def _print_Heaviside(self, expr, exp=None): tex = r"\theta\left(%s\right)" % self._print(expr.args[0]) if exp: tex = r"\left(%s\right)^{%s}" % (tex, exp) return tex def _print_KroneckerDelta(self, expr, exp=None): i = self._print(expr.args[0]) j = self._print(expr.args[1]) if expr.args[0].is_Atom and expr.args[1].is_Atom: tex = r'\delta_{%s %s}' % (i, j) else: tex = r'\delta_{%s, %s}' % (i, j) if exp: tex = r'\left(%s\right)^{%s}' % (tex, exp) return tex def _print_LeviCivita(self, expr, exp=None): indices = map(self._print, expr.args) if all(x.is_Atom for x in expr.args): tex = r'\varepsilon_{%s}' % " ".join(indices) else: tex = r'\varepsilon_{%s}' % ", ".join(indices) if exp: tex = r'\left(%s\right)^{%s}' % (tex, exp) return tex def _print_ProductSet(self, p): if len(p.sets) > 1 and not has_variety(p.sets): return self._print(p.sets[0]) + "^{%d}" % len(p.sets) else: return r" \times ".join(self._print(set) for set in p.sets) def _print_RandomDomain(self, d): if hasattr(d, 'as_boolean'): return 'Domain: ' + self._print(d.as_boolean()) elif hasattr(d, 'set'): return ('Domain: ' + self._print(d.symbols) + ' in ' + self._print(d.set)) elif hasattr(d, 'symbols'): return 'Domain on ' + self._print(d.symbols) else: return self._print(None) def _print_FiniteSet(self, s): items = sorted(s.args, key=default_sort_key) return self._print_set(items) def _print_set(self, s): items = sorted(s, key=default_sort_key) items = ", ".join(map(self._print, items)) return r"\left\{%s\right\}" % items _print_frozenset = _print_set def _print_Range(self, s): dots = r'\ldots' if s.start.is_infinite: printset = s.start, dots, s[-1] - s.step, s[-1] elif s.stop.is_infinite or len(s) > 4: it = iter(s) printset = next(it), next(it), dots, s[-1] else: printset = tuple(s) return (r"\left\{" + r", ".join(self._print(el) for el in printset) + r"\right\}") def _print_SeqFormula(self, s): if s.start is S.NegativeInfinity: stop = s.stop printset = (r'\ldots', s.coeff(stop - 3), s.coeff(stop - 2), s.coeff(stop - 1), s.coeff(stop)) elif s.stop is S.Infinity or s.length > 4: printset = s[:4] printset.append(r'\ldots') else: printset = tuple(s) return (r"\left[" + r", ".join(self._print(el) for el in printset) + r"\right]") _print_SeqPer = _print_SeqFormula _print_SeqAdd = _print_SeqFormula _print_SeqMul = _print_SeqFormula def _print_Interval(self, i): if i.start == i.end: return r"\left\{%s\right\}" % self._print(i.start) else: if i.left_open: left = '(' else: left = '[' if i.right_open: right = ')' else: right = ']' return r"\left%s%s, %s\right%s" % \ (left, self._print(i.start), self._print(i.end), right) def _print_AccumulationBounds(self, i): return r"\left\langle %s, %s\right\rangle" % \ (self._print(i.min), self._print(i.max)) def _print_Union(self, u): return r" \cup ".join([self._print(i) for i in u.args]) def _print_Complement(self, u): return r" \setminus ".join([self._print(i) for i in u.args]) def _print_Intersection(self, u): return r" \cap ".join([self._print(i) for i in u.args]) def _print_SymmetricDifference(self, u): return r" \triangle ".join([self._print(i) for i in u.args]) def _print_EmptySet(self, e): return r"\emptyset" def _print_Naturals(self, n): return r"\mathbb{N}" def _print_Naturals0(self, n): return r"\mathbb{N}_0" def _print_Integers(self, i): return r"\mathbb{Z}" def _print_Reals(self, i): return r"\mathbb{R}" def _print_Complexes(self, i): return r"\mathbb{C}" def _print_ImageSet(self, s): sets = s.args[1:] varsets = [r"%s \in %s" % (self._print(var), self._print(setv)) for var, setv in zip(s.lamda.variables, sets)] return r"\left\{%s\; |\; %s\right\}" % ( self._print(s.lamda.expr), ', '.join(varsets)) def _print_ConditionSet(self, s): vars_print = ', '.join([self._print(var) for var in Tuple(s.sym)]) if s.base_set is S.UniversalSet: return r"\left\{%s \mid %s \right\}" % ( vars_print, self._print(s.condition.as_expr())) return r"\left\{%s \mid %s \in %s \wedge %s \right\}" % ( vars_print, vars_print, self._print(s.base_set), self._print(s.condition.as_expr())) def _print_ComplexRegion(self, s): vars_print = ', '.join([self._print(var) for var in s.variables]) return r"\left\{%s\; |\; %s \in %s \right\}" % ( self._print(s.expr), vars_print, self._print(s.sets)) def _print_Contains(self, e): return r"%s \in %s" % tuple(self._print(a) for a in e.args) def _print_FourierSeries(self, s): return self._print_Add(s.truncate()) + self._print(r' + \ldots') def _print_FormalPowerSeries(self, s): return self._print_Add(s.infinite) def _print_FiniteField(self, expr): return r"\mathbb{F}_{%s}" % expr.mod def _print_IntegerRing(self, expr): return r"\mathbb{Z}" def _print_RationalField(self, expr): return r"\mathbb{Q}" def _print_RealField(self, expr): return r"\mathbb{R}" def _print_ComplexField(self, expr): return r"\mathbb{C}" def _print_PolynomialRing(self, expr): domain = self._print(expr.domain) symbols = ", ".join(map(self._print, expr.symbols)) return r"%s\left[%s\right]" % (domain, symbols) def _print_FractionField(self, expr): domain = self._print(expr.domain) symbols = ", ".join(map(self._print, expr.symbols)) return r"%s\left(%s\right)" % (domain, symbols) def _print_PolynomialRingBase(self, expr): domain = self._print(expr.domain) symbols = ", ".join(map(self._print, expr.symbols)) inv = "" if not expr.is_Poly: inv = r"S_<^{-1}" return r"%s%s\left[%s\right]" % (inv, domain, symbols) def _print_Poly(self, poly): cls = poly.__class__.__name__ terms = [] for monom, coeff in poly.terms(): s_monom = '' for i, exp in enumerate(monom): if exp > 0: if exp == 1: s_monom += self._print(poly.gens[i]) else: s_monom += self._print(pow(poly.gens[i], exp)) if coeff.is_Add: if s_monom: s_coeff = r"\left(%s\right)" % self._print(coeff) else: s_coeff = self._print(coeff) else: if s_monom: if coeff is S.One: terms.extend(['+', s_monom]) continue if coeff is S.NegativeOne: terms.extend(['-', s_monom]) continue s_coeff = self._print(coeff) if not s_monom: s_term = s_coeff else: s_term = s_coeff + " " + s_monom if s_term.startswith('-'): terms.extend(['-', s_term[1:]]) else: terms.extend(['+', s_term]) if terms[0] in ['-', '+']: modifier = terms.pop(0) if modifier == '-': terms[0] = '-' + terms[0] expr = ' '.join(terms) gens = list(map(self._print, poly.gens)) domain = "domain=%s" % self._print(poly.get_domain()) args = ", ".join([expr] + gens + [domain]) if cls in accepted_latex_functions: tex = r"\%s {\left(%s \right)}" % (cls, args) else: tex = r"\operatorname{%s}{\left( %s \right)}" % (cls, args) return tex def _print_ComplexRootOf(self, root): cls = root.__class__.__name__ if cls == "ComplexRootOf": cls = "CRootOf" expr = self._print(root.expr) index = root.index if cls in accepted_latex_functions: return r"\%s {\left(%s, %d\right)}" % (cls, expr, index) else: return r"\operatorname{%s} {\left(%s, %d\right)}" % (cls, expr, index) def _print_RootSum(self, expr): cls = expr.__class__.__name__ args = [self._print(expr.expr)] if expr.fun is not S.IdentityFunction: args.append(self._print(expr.fun)) if cls in accepted_latex_functions: return r"\%s {\left(%s\right)}" % (cls, ", ".join(args)) else: return r"\operatorname{%s} {\left(%s\right)}" % (cls, ", ".join(args)) def _print_PolyElement(self, poly): mul_symbol = self._settings['mul_symbol_latex'] return poly.str(self, PRECEDENCE, "{%s}^{%d}", mul_symbol) def _print_FracElement(self, frac): if frac.denom == 1: return self._print(frac.numer) else: numer = self._print(frac.numer) denom = self._print(frac.denom) return r"\frac{%s}{%s}" % (numer, denom) def _print_euler(self, expr, exp=None): m, x = (expr.args[0], None) if len(expr.args) == 1 else expr.args tex = r"E_{%s}" % self._print(m) if exp is not None: tex = r"%s^{%s}" % (tex, self._print(exp)) if x is not None: tex = r"%s\left(%s\right)" % (tex, self._print(x)) return tex def _print_catalan(self, expr, exp=None): tex = r"C_{%s}" % self._print(expr.args[0]) if exp is not None: tex = r"%s^{%s}" % (tex, self._print(exp)) return tex def _print_MellinTransform(self, expr): return r"\mathcal{M}_{%s}\left[%s\right]\left(%s\right)" % (self._print(expr.args[1]), self._print(expr.args[0]), self._print(expr.args[2])) def _print_InverseMellinTransform(self, expr): return r"\mathcal{M}^{-1}_{%s}\left[%s\right]\left(%s\right)" % (self._print(expr.args[1]), self._print(expr.args[0]), self._print(expr.args[2])) def _print_LaplaceTransform(self, expr): return r"\mathcal{L}_{%s}\left[%s\right]\left(%s\right)" % (self._print(expr.args[1]), self._print(expr.args[0]), self._print(expr.args[2])) def _print_InverseLaplaceTransform(self, expr): return r"\mathcal{L}^{-1}_{%s}\left[%s\right]\left(%s\right)" % (self._print(expr.args[1]), self._print(expr.args[0]), self._print(expr.args[2])) def _print_FourierTransform(self, expr): return r"\mathcal{F}_{%s}\left[%s\right]\left(%s\right)" % (self._print(expr.args[1]), self._print(expr.args[0]), self._print(expr.args[2])) def _print_InverseFourierTransform(self, expr): return r"\mathcal{F}^{-1}_{%s}\left[%s\right]\left(%s\right)" % (self._print(expr.args[1]), self._print(expr.args[0]), self._print(expr.args[2])) def _print_SineTransform(self, expr): return r"\mathcal{SIN}_{%s}\left[%s\right]\left(%s\right)" % (self._print(expr.args[1]), self._print(expr.args[0]), self._print(expr.args[2])) def _print_InverseSineTransform(self, expr): return r"\mathcal{SIN}^{-1}_{%s}\left[%s\right]\left(%s\right)" % (self._print(expr.args[1]), self._print(expr.args[0]), self._print(expr.args[2])) def _print_CosineTransform(self, expr): return r"\mathcal{COS}_{%s}\left[%s\right]\left(%s\right)" % (self._print(expr.args[1]), self._print(expr.args[0]), self._print(expr.args[2])) def _print_InverseCosineTransform(self, expr): return r"\mathcal{COS}^{-1}_{%s}\left[%s\right]\left(%s\right)" % (self._print(expr.args[1]), self._print(expr.args[0]), self._print(expr.args[2])) def _print_DMP(self, p): try: if p.ring is not None: # TODO incorporate order return self._print(p.ring.to_sympy(p)) except SympifyError: pass return self._print(repr(p)) def _print_DMF(self, p): return self._print_DMP(p) def _print_Object(self, object): return self._print(Symbol(object.name)) def _print_Morphism(self, morphism): domain = self._print(morphism.domain) codomain = self._print(morphism.codomain) return "%s\\rightarrow %s" % (domain, codomain) def _print_NamedMorphism(self, morphism): pretty_name = self._print(Symbol(morphism.name)) pretty_morphism = self._print_Morphism(morphism) return "%s:%s" % (pretty_name, pretty_morphism) def _print_IdentityMorphism(self, morphism): from sympy.categories import NamedMorphism return self._print_NamedMorphism(NamedMorphism( morphism.domain, morphism.codomain, "id")) def _print_CompositeMorphism(self, morphism): # All components of the morphism have names and it is thus # possible to build the name of the composite. component_names_list = [self._print(Symbol(component.name)) for component in morphism.components] component_names_list.reverse() component_names = "\\circ ".join(component_names_list) + ":" pretty_morphism = self._print_Morphism(morphism) return component_names + pretty_morphism def _print_Category(self, morphism): return "\\mathbf{%s}" % self._print(Symbol(morphism.name)) def _print_Diagram(self, diagram): if not diagram.premises: # This is an empty diagram. return self._print(S.EmptySet) latex_result = self._print(diagram.premises) if diagram.conclusions: latex_result += "\\Longrightarrow %s" % \ self._print(diagram.conclusions) return latex_result def _print_DiagramGrid(self, grid): latex_result = "\\begin{array}{%s}\n" % ("c" * grid.width) for i in range(grid.height): for j in range(grid.width): if grid[i, j]: latex_result += latex(grid[i, j]) latex_result += " " if j != grid.width - 1: latex_result += "& " if i != grid.height - 1: latex_result += "\\\\" latex_result += "\n" latex_result += "\\end{array}\n" return latex_result def _print_FreeModule(self, M): return '{%s}^{%s}' % (self._print(M.ring), self._print(M.rank)) def _print_FreeModuleElement(self, m): # Print as row vector for convenience, for now. return r"\left[ %s \right]" % ",".join( '{' + self._print(x) + '}' for x in m) def _print_SubModule(self, m): return r"\left\langle %s \right\rangle" % ",".join( '{' + self._print(x) + '}' for x in m.gens) def _print_ModuleImplementedIdeal(self, m): return r"\left\langle %s \right\rangle" % ",".join( '{' + self._print(x) + '}' for [x] in m._module.gens) def _print_Quaternion(self, expr): # TODO: This expression is potentially confusing, # shall we print it as `Quaternion( ... )`? s = [self.parenthesize(i, PRECEDENCE["Mul"], strict=True) for i in expr.args] a = [s[0]] + [i+" "+j for i, j in zip(s[1:], "ijk")] return " + ".join(a) def _print_QuotientRing(self, R): # TODO nicer fractions for few generators... return r"\frac{%s}{%s}" % (self._print(R.ring), self._print(R.base_ideal)) def _print_QuotientRingElement(self, x): return r"{%s} + {%s}" % (self._print(x.data), self._print(x.ring.base_ideal)) def _print_QuotientModuleElement(self, m): return r"{%s} + {%s}" % (self._print(m.data), self._print(m.module.killed_module)) def _print_QuotientModule(self, M): # TODO nicer fractions for few generators... return r"\frac{%s}{%s}" % (self._print(M.base), self._print(M.killed_module)) def _print_MatrixHomomorphism(self, h): return r"{%s} : {%s} \to {%s}" % (self._print(h._sympy_matrix()), self._print(h.domain), self._print(h.codomain)) def _print_BaseScalarField(self, field): string = field._coord_sys._names[field._index] return r'\boldsymbol{\mathrm{%s}}' % self._print(Symbol(string)) def _print_BaseVectorField(self, field): string = field._coord_sys._names[field._index] return r'\partial_{%s}' % self._print(Symbol(string)) def _print_Differential(self, diff): field = diff._form_field if hasattr(field, '_coord_sys'): string = field._coord_sys._names[field._index] return r'\mathrm{d}%s' % self._print(Symbol(string)) else: return 'd(%s)' % self._print(field) string = self._print(field) return r'\mathrm{d}\left(%s\right)' % string def _print_Tr(self, p): #Todo: Handle indices contents = self._print(p.args[0]) return r'\mbox{Tr}\left(%s\right)' % (contents) def _print_totient(self, expr, exp=None): if exp is not None: return r'\left(\phi\left(%s\right)\right)^{%s}' % (self._print(expr.args[0]), self._print(exp)) return r'\phi\left(%s\right)' % self._print(expr.args[0]) def _print_reduced_totient(self, expr, exp=None): if exp is not None: return r'\left(\lambda\left(%s\right)\right)^{%s}' % (self._print(expr.args[0]), self._print(exp)) return r'\lambda\left(%s\right)' % self._print(expr.args[0]) def _print_divisor_sigma(self, expr, exp=None): if len(expr.args) == 2: tex = r"_%s\left(%s\right)" % tuple(map(self._print, (expr.args[1], expr.args[0]))) else: tex = r"\left(%s\right)" % self._print(expr.args[0]) if exp is not None: return r"\sigma^{%s}%s" % (self._print(exp), tex) return r"\sigma%s" % tex def _print_udivisor_sigma(self, expr, exp=None): if len(expr.args) == 2: tex = r"_%s\left(%s\right)" % tuple(map(self._print, (expr.args[1], expr.args[0]))) else: tex = r"\left(%s\right)" % self._print(expr.args[0]) if exp is not None: return r"\sigma^*^{%s}%s" % (self._print(exp), tex) return r"\sigma^*%s" % tex def _print_primenu(self, expr, exp=None): if exp is not None: return r'\left(\nu\left(%s\right)\right)^{%s}' % (self._print(expr.args[0]), self._print(exp)) return r'\nu\left(%s\right)' % self._print(expr.args[0]) def _print_primeomega(self, expr, exp=None): if exp is not None: return r'\left(\Omega\left(%s\right)\right)^{%s}' % (self._print(expr.args[0]), self._print(exp)) return r'\Omega\left(%s\right)' % self._print(expr.args[0]) def translate(s): r''' Check for a modifier ending the string. If present, convert the modifier to latex and translate the rest recursively. Given a description of a Greek letter or other special character, return the appropriate latex. Let everything else pass as given. >>> from sympy.printing.latex import translate >>> translate('alphahatdotprime') "{\\dot{\\hat{\\alpha}}}'" ''' # Process the rest tex = tex_greek_dictionary.get(s) if tex: return tex elif s.lower() in greek_letters_set: return "\\" + s.lower() elif s in other_symbols: return "\\" + s else: # Process modifiers, if any, and recurse for key in sorted(modifier_dict.keys(), key=lambda k:len(k), reverse=True): if s.lower().endswith(key) and len(s)>len(key): return modifier_dict[key](translate(s[:-len(key)])) return s def latex(expr, fold_frac_powers=False, fold_func_brackets=False, fold_short_frac=None, inv_trig_style="abbreviated", itex=False, ln_notation=False, long_frac_ratio=None, mat_delim="[", mat_str=None, mode="plain", mul_symbol=None, order=None, symbol_names=None): r"""Convert the given expression to LaTeX string representation. Parameters ========== fold_frac_powers : boolean, optional Emit ``^{p/q}`` instead of ``^{\frac{p}{q}}`` for fractional powers. fold_func_brackets : boolean, optional Fold function brackets where applicable. fold_short_frac : boolean, optional Emit ``p / q`` instead of ``\frac{p}{q}`` when the denominator is simple enough (at most two terms and no powers). The default value is ``True`` for inline mode, ``False`` otherwise. inv_trig_style : string, optional How inverse trig functions should be displayed. Can be one of ``abbreviated``, ``full``, or ``power``. Defaults to ``abbreviated``. itex : boolean, optional Specifies if itex-specific syntax is used, including emitting ``$$...$$``. ln_notation : boolean, optional If set to ``True``, ``\ln`` is used instead of default ``\log``. long_frac_ratio : float or None, optional The allowed ratio of the width of the numerator to the width of the denominator before the printer breaks off long fractions. If ``None`` (the default value), long fractions are not broken up. mat_delim : string, optional The delimiter to wrap around matrices. Can be one of ``[``, ``(``, or the empty string. Defaults to ``[``. mat_str : string, optional Which matrix environment string to emit. ``smallmatrix``, ``matrix``, ``array``, etc. Defaults to ``smallmatrix`` for inline mode, ``matrix`` for matrices of no more than 10 columns, and ``array`` otherwise. mode: string, optional Specifies how the generated code will be delimited. ``mode`` can be one of ``plain``, ``inline``, ``equation`` or ``equation*``. If ``mode`` is set to ``plain``, then the resulting code will not be delimited at all (this is the default). If ``mode`` is set to ``inline`` then inline LaTeX ``$...$`` will be used. If ``mode`` is set to ``equation`` or ``equation*``, the resulting code will be enclosed in the ``equation`` or ``equation*`` environment (remember to import ``amsmath`` for ``equation*``), unless the ``itex`` option is set. In the latter case, the ``$$...$$`` syntax is used. mul_symbol : string or None, optional The symbol to use for multiplication. Can be one of ``None``, ``ldot``, ``dot``, or ``times``. order: string, optional Any of the supported monomial orderings (currently ``lex``, ``grlex``, or ``grevlex``), ``old``, and ``none``. This parameter does nothing for Mul objects. Setting order to ``old`` uses the compatibility ordering for Add defined in Printer. For very large expressions, set the ``order`` keyword to ``none`` if speed is a concern. symbol_names : dictionary of strings mapped to symbols, optional Dictionary of symbols and the custom strings they should be emitted as. Notes ===== Not using a print statement for printing, results in double backslashes for latex commands since that's the way Python escapes backslashes in strings. >>> from sympy import latex, Rational >>> from sympy.abc import tau >>> latex((2*tau)**Rational(7,2)) '8 \\sqrt{2} \\tau^{\\frac{7}{2}}' >>> print(latex((2*tau)**Rational(7,2))) 8 \sqrt{2} \tau^{\frac{7}{2}} Examples ======== >>> from sympy import latex, pi, sin, asin, Integral, Matrix, Rational, log >>> from sympy.abc import x, y, mu, r, tau Basic usage: >>> print(latex((2*tau)**Rational(7,2))) 8 \sqrt{2} \tau^{\frac{7}{2}} ``mode`` and ``itex`` options: >>> print(latex((2*mu)**Rational(7,2), mode='plain')) 8 \sqrt{2} \mu^{\frac{7}{2}} >>> print(latex((2*tau)**Rational(7,2), mode='inline')) $8 \sqrt{2} \tau^{7 / 2}$ >>> print(latex((2*mu)**Rational(7,2), mode='equation*')) \begin{equation*}8 \sqrt{2} \mu^{\frac{7}{2}}\end{equation*} >>> print(latex((2*mu)**Rational(7,2), mode='equation')) \begin{equation}8 \sqrt{2} \mu^{\frac{7}{2}}\end{equation} >>> print(latex((2*mu)**Rational(7,2), mode='equation', itex=True)) $$8 \sqrt{2} \mu^{\frac{7}{2}}$$ >>> print(latex((2*mu)**Rational(7,2), mode='plain')) 8 \sqrt{2} \mu^{\frac{7}{2}} >>> print(latex((2*tau)**Rational(7,2), mode='inline')) $8 \sqrt{2} \tau^{7 / 2}$ >>> print(latex((2*mu)**Rational(7,2), mode='equation*')) \begin{equation*}8 \sqrt{2} \mu^{\frac{7}{2}}\end{equation*} >>> print(latex((2*mu)**Rational(7,2), mode='equation')) \begin{equation}8 \sqrt{2} \mu^{\frac{7}{2}}\end{equation} >>> print(latex((2*mu)**Rational(7,2), mode='equation', itex=True)) $$8 \sqrt{2} \mu^{\frac{7}{2}}$$ Fraction options: >>> print(latex((2*tau)**Rational(7,2), fold_frac_powers=True)) 8 \sqrt{2} \tau^{7/2} >>> print(latex((2*tau)**sin(Rational(7,2)))) \left(2 \tau\right)^{\sin{\left(\frac{7}{2} \right)}} >>> print(latex((2*tau)**sin(Rational(7,2)), fold_func_brackets=True)) \left(2 \tau\right)^{\sin {\frac{7}{2}}} >>> print(latex(3*x**2/y)) \frac{3 x^{2}}{y} >>> print(latex(3*x**2/y, fold_short_frac=True)) 3 x^{2} / y >>> print(latex(Integral(r, r)/2/pi, long_frac_ratio=2)) \frac{\int r\, dr}{2 \pi} >>> print(latex(Integral(r, r)/2/pi, long_frac_ratio=0)) \frac{1}{2 \pi} \int r\, dr Multiplication options: >>> print(latex((2*tau)**sin(Rational(7,2)), mul_symbol="times")) \left(2 \times \tau\right)^{\sin{\left(\frac{7}{2} \right)}} Trig options: >>> print(latex(asin(Rational(7,2)))) \operatorname{asin}{\left(\frac{7}{2} \right)} >>> print(latex(asin(Rational(7,2)), inv_trig_style="full")) \arcsin{\left(\frac{7}{2} \right)} >>> print(latex(asin(Rational(7,2)), inv_trig_style="power")) \sin^{-1}{\left(\frac{7}{2} \right)} Matrix options: >>> print(latex(Matrix(2, 1, [x, y]))) \left[\begin{matrix}x\\y\end{matrix}\right] >>> print(latex(Matrix(2, 1, [x, y]), mat_str = "array")) \left[\begin{array}{c}x\\y\end{array}\right] >>> print(latex(Matrix(2, 1, [x, y]), mat_delim="(")) \left(\begin{matrix}x\\y\end{matrix}\right) Custom printing of symbols: >>> print(latex(x**2, symbol_names={x: 'x_i'})) x_i^{2} Logarithms: >>> print(latex(log(10))) \log{\left(10 \right)} >>> print(latex(log(10), ln_notation=True)) \ln{\left(10 \right)} ``latex()`` also supports the builtin container types list, tuple, and dictionary. >>> print(latex([2/x, y], mode='inline')) $\left[ 2 / x, \quad y\right]$ """ if symbol_names is None: symbol_names = {} settings = { 'fold_frac_powers' : fold_frac_powers, 'fold_func_brackets' : fold_func_brackets, 'fold_short_frac' : fold_short_frac, 'inv_trig_style' : inv_trig_style, 'itex' : itex, 'ln_notation' : ln_notation, 'long_frac_ratio' : long_frac_ratio, 'mat_delim' : mat_delim, 'mat_str' : mat_str, 'mode' : mode, 'mul_symbol' : mul_symbol, 'order' : order, 'symbol_names' : symbol_names, } return LatexPrinter(settings).doprint(expr) def print_latex(expr, **settings): """Prints LaTeX representation of the given expression. Takes the same settings as ``latex()``.""" print(latex(expr, **settings))

854361b66bcf591a98bb01b662400db6ddf75a2ea64fe32c564cfe06422c4079

"""Printing subsystem driver SymPy's printing system works the following way: Any expression can be passed to a designated Printer who then is responsible to return an adequate representation of that expression. **The basic concept is the following:** 1. Let the object print itself if it knows how. 2. Take the best fitting method defined in the printer. 3. As fall-back use the emptyPrinter method for the printer. Which Method is Responsible for Printing? ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ The whole printing process is started by calling ``.doprint(expr)`` on the printer which you want to use. This method looks for an appropriate method which can print the given expression in the given style that the printer defines. While looking for the method, it follows these steps: 1. **Let the object print itself if it knows how.** The printer looks for a specific method in every object. The name of that method depends on the specific printer and is defined under ``Printer.printmethod``. For example, StrPrinter calls ``_sympystr`` and LatexPrinter calls ``_latex``. Look at the documentation of the printer that you want to use. The name of the method is specified there. This was the original way of doing printing in sympy. Every class had its own latex, mathml, str and repr methods, but it turned out that it is hard to produce a high quality printer, if all the methods are spread out that far. Therefore all printing code was combined into the different printers, which works great for built-in sympy objects, but not that good for user defined classes where it is inconvenient to patch the printers. 2. **Take the best fitting method defined in the printer.** The printer loops through expr classes (class + its bases), and tries to dispatch the work to ``_print_<EXPR_CLASS>`` e.g., suppose we have the following class hierarchy:: Basic | Atom | Number | Rational then, for ``expr=Rational(...)``, the Printer will try to call printer methods in the order as shown in the figure below:: p._print(expr) | |-- p._print_Rational(expr) | |-- p._print_Number(expr) | |-- p._print_Atom(expr) | `-- p._print_Basic(expr) if ``._print_Rational`` method exists in the printer, then it is called, and the result is returned back. Otherwise, the printer tries to call ``._print_Number`` and so on. 3. **As a fall-back use the emptyPrinter method for the printer.** As fall-back ``self.emptyPrinter`` will be called with the expression. If not defined in the Printer subclass this will be the same as ``str(expr)``. Example of Custom Printer ^^^^^^^^^^^^^^^^^^^^^^^^^ .. _printer_example: In the example below, we have a printer which prints the derivative of a function in a shorter form. .. code-block:: python from sympy import Symbol from sympy.printing.latex import LatexPrinter, print_latex from sympy.core.function import UndefinedFunction, Function class MyLatexPrinter(LatexPrinter): \"\"\"Print derivative of a function of symbols in a shorter form. \"\"\" def _print_Derivative(self, expr): function, *vars = expr.args if not isinstance(type(function), UndefinedFunction) or \\ not all(isinstance(i, Symbol) for i in vars): return super()._print_Derivative(expr) # If you want the printer to work correctly for nested # expressions then use self._print() instead of str() or latex(). # See the example of nested modulo below in the custom printing # method section. return "{}_{{{}}}".format( self._print(Symbol(function.func.__name__)), ''.join(self._print(i) for i in vars)) def print_my_latex(expr): \"\"\" Most of the printers define their own wrappers for print(). These wrappers usually take printer settings. Our printer does not have any settings. \"\"\" print(MyLatexPrinter().doprint(expr)) y = Symbol("y") x = Symbol("x") f = Function("f") expr = f(x, y).diff(x, y) # Print the expression using the normal latex printer and our custom # printer. print_latex(expr) print_my_latex(expr) The output of the code above is:: \\frac{\\partial^{2}}{\\partial x\\partial y} f{\\left(x,y \\right)} f_{xy} Example of Custom Printing Method ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ In the example below, the latex printing of the modulo operator is modified. This is done by overriding the method ``_latex`` of ``Mod``. .. code-block:: python from sympy import Symbol, Mod, Integer from sympy.printing.latex import print_latex class ModOp(Mod): def _latex(self, printer=None): # Always use printer.doprint() otherwise nested expressions won't # work. See the example of ModOpWrong. a, b = [printer.doprint(i) for i in self.args] return r"\\operatorname{Mod}{\\left( %s,%s \\right)}" % (a,b) class ModOpWrong(Mod): def _latex(self, printer=None): a, b = [str(i) for i in self.args] return r"\\operatorname{Mod}{\\left( %s,%s \\right)}" % (a,b) x = Symbol('x') m = Symbol('m') print_latex(ModOp(x, m)) print_latex(Mod(x, m)) # Nested modulo. print_latex(ModOp(ModOp(x, m), Integer(7))) print_latex(ModOpWrong(ModOpWrong(x, m), Integer(7))) The output of the code above is:: \\operatorname{Mod}{\\left( x,m \\right)} x\\bmod{m} \\operatorname{Mod}{\\left( \\operatorname{Mod}{\\left( x,m \\right)},7 \\right)} \\operatorname{Mod}{\\left( ModOpWrong(x, m),7 \\right)} """ from __future__ import print_function, division from contextlib import contextmanager from sympy import Basic, Add from sympy.core.core import BasicMeta from sympy.core.function import AppliedUndef, UndefinedFunction, Function from functools import cmp_to_key @contextmanager def printer_context(printer, **kwargs): original = printer._context.copy() try: printer._context.update(kwargs) yield finally: printer._context = original class Printer(object): """ Generic printer Its job is to provide infrastructure for implementing new printers easily. If you want to define your custom Printer or your custom printing method for your custom class then see the example above: printer_example_ . """ _global_settings = {} _default_settings = {} emptyPrinter = str printmethod = None def __init__(self, settings=None): self._str = str self._settings = self._default_settings.copy() self._context = dict() # mutable during printing for key, val in self._global_settings.items(): if key in self._default_settings: self._settings[key] = val if settings is not None: self._settings.update(settings) if len(self._settings) > len(self._default_settings): for key in self._settings: if key not in self._default_settings: raise TypeError("Unknown setting '%s'." % key) # _print_level is the number of times self._print() was recursively # called. See StrPrinter._print_Float() for an example of usage self._print_level = 0 @classmethod def set_global_settings(cls, **settings): """Set system-wide printing settings. """ for key, val in settings.items(): if val is not None: cls._global_settings[key] = val @property def order(self): if 'order' in self._settings: return self._settings['order'] else: raise AttributeError("No order defined.") def doprint(self, expr): """Returns printer's representation for expr (as a string)""" return self._str(self._print(expr)) def _print(self, expr, **kwargs): """Internal dispatcher Tries the following concepts to print an expression: 1. Let the object print itself if it knows how. 2. Take the best fitting method defined in the printer. 3. As fall-back use the emptyPrinter method for the printer. """ self._print_level += 1 try: # If the printer defines a name for a printing method # (Printer.printmethod) and the object knows for itself how it # should be printed, use that method. if (self.printmethod and hasattr(expr, self.printmethod) and not isinstance(expr, BasicMeta)): return getattr(expr, self.printmethod)(self, **kwargs) # See if the class of expr is known, or if one of its super # classes is known, and use that print function # Exception: ignore the subclasses of Undefined, so that, e.g., # Function('gamma') does not get dispatched to _print_gamma classes = type(expr).__mro__ if AppliedUndef in classes: classes = classes[classes.index(AppliedUndef):] if UndefinedFunction in classes: classes = classes[classes.index(UndefinedFunction):] # Another exception: if someone subclasses a known function, e.g., # gamma, and changes the name, then ignore _print_gamma if Function in classes: i = classes.index(Function) classes = tuple(c for c in classes[:i] if \ c.__name__ == classes[0].__name__ or \ c.__name__.endswith("Base")) + classes[i:] for cls in classes: printmethod = '_print_' + cls.__name__ if hasattr(self, printmethod): return getattr(self, printmethod)(expr, **kwargs) # Unknown object, fall back to the emptyPrinter. return self.emptyPrinter(expr) finally: self._print_level -= 1 def _as_ordered_terms(self, expr, order=None): """A compatibility function for ordering terms in Add. """ order = order or self.order if order == 'old': return sorted(Add.make_args(expr), key=cmp_to_key(Basic._compare_pretty)) else: return expr.as_ordered_terms(order=order)

6b39546502b137419017de8d909a56a5ab00a980e7cd9f117ce8a62fb3735607

""" Mathematica code printer """ from __future__ import print_function, division from sympy.printing.codeprinter import CodePrinter from sympy.printing.str import StrPrinter from sympy.printing.precedence import precedence # Used in MCodePrinter._print_Function(self) known_functions = { "exp": [(lambda x: True, "Exp")], "log": [(lambda x: True, "Log")], "sin": [(lambda x: True, "Sin")], "cos": [(lambda x: True, "Cos")], "tan": [(lambda x: True, "Tan")], "cot": [(lambda x: True, "Cot")], "asin": [(lambda x: True, "ArcSin")], "acos": [(lambda x: True, "ArcCos")], "atan": [(lambda x: True, "ArcTan")], "sinh": [(lambda x: True, "Sinh")], "cosh": [(lambda x: True, "Cosh")], "tanh": [(lambda x: True, "Tanh")], "coth": [(lambda x: True, "Coth")], "sech": [(lambda x: True, "Sech")], "csch": [(lambda x: True, "Csch")], "asinh": [(lambda x: True, "ArcSinh")], "acosh": [(lambda x: True, "ArcCosh")], "atanh": [(lambda x: True, "ArcTanh")], "acoth": [(lambda x: True, "ArcCoth")], "asech": [(lambda x: True, "ArcSech")], "acsch": [(lambda x: True, "ArcCsch")], "conjugate": [(lambda x: True, "Conjugate")], "Max": [(lambda *x: True, "Max")], "Min": [(lambda *x: True, "Min")], } class MCodePrinter(CodePrinter): """A printer to convert python expressions to strings of the Wolfram's Mathematica code """ printmethod = "_mcode" _default_settings = { 'order': None, 'full_prec': 'auto', 'precision': 15, 'user_functions': {}, 'human': True, 'allow_unknown_functions': False, } _number_symbols = set() _not_supported = set() def __init__(self, settings={}): """Register function mappings supplied by user""" CodePrinter.__init__(self, settings) self.known_functions = dict(known_functions) userfuncs = settings.get('user_functions', {}) for k, v in userfuncs.items(): if not isinstance(v, list): userfuncs[k] = [(lambda *x: True, v)] self.known_functions.update(userfuncs) doprint = StrPrinter.doprint def _print_Pow(self, expr): PREC = precedence(expr) return '%s^%s' % (self.parenthesize(expr.base, PREC), self.parenthesize(expr.exp, PREC)) def _print_Mul(self, expr): PREC = precedence(expr) c, nc = expr.args_cnc() res = super(MCodePrinter, self)._print_Mul(expr.func(*c)) if nc: res += '*' res += '**'.join(self.parenthesize(a, PREC) for a in nc) return res def _print_Pi(self, expr): return 'Pi' def _print_Infinity(self, expr): return 'Infinity' def _print_NegativeInfinity(self, expr): return '-Infinity' def _print_list(self, expr): return '{' + ', '.join(self.doprint(a) for a in expr) + '}' _print_tuple = _print_list _print_Tuple = _print_list def _print_Matrix(self, expr): return self._print_list( [self._print_list(expr.row(i)) for i in range(expr.rows)] ) _print_ImmutableMatrix = _print_Matrix _print_ImmutableDenseMatrix = _print_Matrix _print_MutableDenseMatrix = _print_Matrix def _print_SparseMatrix(self, expr): from sympy.core.compatibility import default_sort_key def print_rule(pos, val): return '{} -> {}'.format( self.doprint((pos[0]+1, pos[1]+1)), self.doprint(val)) def print_data(): return self._print_list( [print_rule(key, value) for key, value in sorted(expr._smat.items(), key=default_sort_key)] ) def print_dims(): return self._print_list( [self.doprint(expr.rows), self.doprint(expr.cols)] ) return 'SparseArray[{}, {}]'.format(print_data(), print_dims()) _print_MutableSparseMatrix = _print_SparseMatrix _print_ImmutableSparseMatrix = _print_SparseMatrix def _print_Function(self, expr): if expr.func.__name__ in self.known_functions: cond_mfunc = self.known_functions[expr.func.__name__] for cond, mfunc in cond_mfunc: if cond(*expr.args): return "%s[%s]" % (mfunc, self.stringify(expr.args, ", ")) return expr.func.__name__ + "[%s]" % self.stringify(expr.args, ", ") _print_MinMaxBase = _print_Function def _print_Integral(self, expr): if len(expr.variables) == 1 and not expr.limits[0][1:]: args = [expr.args[0], expr.variables[0]] else: args = expr.args return "Hold[Integrate[" + ', '.join(self.doprint(a) for a in args) + "]]" def _print_Sum(self, expr): return "Hold[Sum[" + ', '.join(self.doprint(a) for a in expr.args) + "]]" def _print_Derivative(self, expr): dexpr = expr.expr dvars = [i[0] if i[1] == 1 else i for i in expr.variable_count] return "Hold[D[" + ', '.join(self.doprint(a) for a in [dexpr] + dvars) + "]]" def mathematica_code(expr, **settings): r"""Converts an expr to a string of the Wolfram Mathematica code Examples ======== >>> from sympy import mathematica_code as mcode, symbols, sin >>> x = symbols('x') >>> mcode(sin(x).series(x).removeO()) '(1/120)*x^5 - 1/6*x^3 + x' """ return MCodePrinter(settings).doprint(expr)

86574bafe10700eba05f08675f81fe77528e845b3a39151fcd512621d21c016a

from __future__ import print_function, division from functools import wraps from sympy.core import Add, Mul, Pow, S, sympify, Float from sympy.core.basic import Basic from sympy.core.containers import Tuple from sympy.core.compatibility import default_sort_key, string_types from sympy.core.function import Lambda from sympy.core.mul import _keep_coeff from sympy.core.symbol import Symbol from sympy.printing.str import StrPrinter from sympy.printing.precedence import precedence # Backwards compatibility from sympy.codegen.ast import Assignment class requires(object): """ Decorator for registering requirements on print methods. """ def __init__(self, **kwargs): self._req = kwargs def __call__(self, method): def _method_wrapper(self_, *args, **kwargs): for k, v in self._req.items(): getattr(self_, k).update(v) return method(self_, *args, **kwargs) return wraps(method)(_method_wrapper) class AssignmentError(Exception): """ Raised if an assignment variable for a loop is missing. """ pass class CodePrinter(StrPrinter): """ The base class for code-printing subclasses. """ _operators = { 'and': '&&', 'or': '||', 'not': '!', } _default_settings = { 'order': None, 'full_prec': 'auto', 'error_on_reserved': False, 'reserved_word_suffix': '_', 'human': True, 'inline': False, 'allow_unknown_functions': False, } def __init__(self, settings=None): super(CodePrinter, self).__init__(settings=settings) if not hasattr(self, 'reserved_words'): self.reserved_words = set() def doprint(self, expr, assign_to=None): """ Print the expression as code. Parameters ---------- expr : Expression The expression to be printed. assign_to : Symbol, MatrixSymbol, or string (optional) If provided, the printed code will set the expression to a variable with name ``assign_to``. """ from sympy.matrices.expressions.matexpr import MatrixSymbol if isinstance(assign_to, string_types): if expr.is_Matrix: assign_to = MatrixSymbol(assign_to, *expr.shape) else: assign_to = Symbol(assign_to) elif not isinstance(assign_to, (Basic, type(None))): raise TypeError("{0} cannot assign to object of type {1}".format( type(self).__name__, type(assign_to))) if assign_to: expr = Assignment(assign_to, expr) else: # _sympify is not enough b/c it errors on iterables expr = sympify(expr) # keep a set of expressions that are not strictly translatable to Code # and number constants that must be declared and initialized self._not_supported = set() self._number_symbols = set() lines = self._print(expr).splitlines() # format the output if self._settings["human"]: frontlines = [] if len(self._not_supported) > 0: frontlines.append(self._get_comment( "Not supported in {0}:".format(self.language))) for expr in sorted(self._not_supported, key=str): frontlines.append(self._get_comment(type(expr).__name__)) for name, value in sorted(self._number_symbols, key=str): frontlines.append(self._declare_number_const(name, value)) lines = frontlines + lines lines = self._format_code(lines) result = "\n".join(lines) else: lines = self._format_code(lines) num_syms = set([(k, self._print(v)) for k, v in self._number_symbols]) result = (num_syms, self._not_supported, "\n".join(lines)) self._not_supported = set() self._number_symbols = set() return result def _doprint_loops(self, expr, assign_to=None): # Here we print an expression that contains Indexed objects, they # correspond to arrays in the generated code. The low-level implementation # involves looping over array elements and possibly storing results in temporary # variables or accumulate it in the assign_to object. if self._settings.get('contract', True): from sympy.tensor import get_contraction_structure # Setup loops over non-dummy indices -- all terms need these indices = self._get_expression_indices(expr, assign_to) # Setup loops over dummy indices -- each term needs separate treatment dummies = get_contraction_structure(expr) else: indices = [] dummies = {None: (expr,)} openloop, closeloop = self._get_loop_opening_ending(indices) # terms with no summations first if None in dummies: text = StrPrinter.doprint(self, Add(*dummies[None])) else: # If all terms have summations we must initialize array to Zero text = StrPrinter.doprint(self, 0) # skip redundant assignments (where lhs == rhs) lhs_printed = self._print(assign_to) lines = [] if text != lhs_printed: lines.extend(openloop) if assign_to is not None: text = self._get_statement("%s = %s" % (lhs_printed, text)) lines.append(text) lines.extend(closeloop) # then terms with summations for d in dummies: if isinstance(d, tuple): indices = self._sort_optimized(d, expr) openloop_d, closeloop_d = self._get_loop_opening_ending( indices) for term in dummies[d]: if term in dummies and not ([list(f.keys()) for f in dummies[term]] == [[None] for f in dummies[term]]): # If one factor in the term has it's own internal # contractions, those must be computed first. # (temporary variables?) raise NotImplementedError( "FIXME: no support for contractions in factor yet") else: # We need the lhs expression as an accumulator for # the loops, i.e # # for (int d=0; d < dim; d++){ # lhs[] = lhs[] + term[][d] # } ^.................. the accumulator # # We check if the expression already contains the # lhs, and raise an exception if it does, as that # syntax is currently undefined. FIXME: What would be # a good interpretation? if assign_to is None: raise AssignmentError( "need assignment variable for loops") if term.has(assign_to): raise ValueError("FIXME: lhs present in rhs,\ this is undefined in CodePrinter") lines.extend(openloop) lines.extend(openloop_d) text = "%s = %s" % (lhs_printed, StrPrinter.doprint( self, assign_to + term)) lines.append(self._get_statement(text)) lines.extend(closeloop_d) lines.extend(closeloop) return "\n".join(lines) def _get_expression_indices(self, expr, assign_to): from sympy.tensor import get_indices rinds, junk = get_indices(expr) linds, junk = get_indices(assign_to) # support broadcast of scalar if linds and not rinds: rinds = linds if rinds != linds: raise ValueError("lhs indices must match non-dummy" " rhs indices in %s" % expr) return self._sort_optimized(rinds, assign_to) def _sort_optimized(self, indices, expr): from sympy.tensor.indexed import Indexed if not indices: return [] # determine optimized loop order by giving a score to each index # the index with the highest score are put in the innermost loop. score_table = {} for i in indices: score_table[i] = 0 arrays = expr.atoms(Indexed) for arr in arrays: for p, ind in enumerate(arr.indices): try: score_table[ind] += self._rate_index_position(p) except KeyError: pass return sorted(indices, key=lambda x: score_table[x]) def _rate_index_position(self, p): """function to calculate score based on position among indices This method is used to sort loops in an optimized order, see CodePrinter._sort_optimized() """ raise NotImplementedError("This function must be implemented by " "subclass of CodePrinter.") def _get_statement(self, codestring): """Formats a codestring with the proper line ending.""" raise NotImplementedError("This function must be implemented by " "subclass of CodePrinter.") def _get_comment(self, text): """Formats a text string as a comment.""" raise NotImplementedError("This function must be implemented by " "subclass of CodePrinter.") def _declare_number_const(self, name, value): """Declare a numeric constant at the top of a function""" raise NotImplementedError("This function must be implemented by " "subclass of CodePrinter.") def _format_code(self, lines): """Take in a list of lines of code, and format them accordingly. This may include indenting, wrapping long lines, etc...""" raise NotImplementedError("This function must be implemented by " "subclass of CodePrinter.") def _get_loop_opening_ending(self, indices): """Returns a tuple (open_lines, close_lines) containing lists of codelines""" raise NotImplementedError("This function must be implemented by " "subclass of CodePrinter.") def _print_Dummy(self, expr): if expr.name.startswith('Dummy_'): return '_' + expr.name else: return '%s_%d' % (expr.name, expr.dummy_index) def _print_CodeBlock(self, expr): return '\n'.join([self._print(i) for i in expr.args]) def _print_String(self, string): return str(string) def _print_QuotedString(self, arg): return '"%s"' % arg.text def _print_Comment(self, string): return self._get_comment(str(string)) def _print_Assignment(self, expr): from sympy.functions.elementary.piecewise import Piecewise from sympy.matrices.expressions.matexpr import MatrixSymbol from sympy.tensor.indexed import IndexedBase lhs = expr.lhs rhs = expr.rhs # We special case assignments that take multiple lines if isinstance(expr.rhs, Piecewise): # Here we modify Piecewise so each expression is now # an Assignment, and then continue on the print. expressions = [] conditions = [] for (e, c) in rhs.args: expressions.append(Assignment(lhs, e)) conditions.append(c) temp = Piecewise(*zip(expressions, conditions)) return self._print(temp) elif isinstance(lhs, MatrixSymbol): # Here we form an Assignment for each element in the array, # printing each one. lines = [] for (i, j) in self._traverse_matrix_indices(lhs): temp = Assignment(lhs[i, j], rhs[i, j]) code0 = self._print(temp) lines.append(code0) return "\n".join(lines) elif self._settings.get("contract", False) and (lhs.has(IndexedBase) or rhs.has(IndexedBase)): # Here we check if there is looping to be done, and if so # print the required loops. return self._doprint_loops(rhs, lhs) else: lhs_code = self._print(lhs) rhs_code = self._print(rhs) return self._get_statement("%s = %s" % (lhs_code, rhs_code)) def _print_AugmentedAssignment(self, expr): lhs_code = self._print(expr.lhs) rhs_code = self._print(expr.rhs) return self._get_statement("{0} {1} {2}".format( *map(lambda arg: self._print(arg), [lhs_code, expr.op, rhs_code]))) def _print_FunctionCall(self, expr): return '%s(%s)' % ( expr.name, ', '.join(map(lambda arg: self._print(arg), expr.function_args))) def _print_Variable(self, expr): return self._print(expr.symbol) def _print_Statement(self, expr): arg, = expr.args return self._get_statement(self._print(arg)) def _print_Symbol(self, expr): name = super(CodePrinter, self)._print_Symbol(expr) if name in self.reserved_words: if self._settings['error_on_reserved']: msg = ('This expression includes the symbol "{}" which is a ' 'reserved keyword in this language.') raise ValueError(msg.format(name)) return name + self._settings['reserved_word_suffix'] else: return name def _print_Function(self, expr): if expr.func.__name__ in self.known_functions: cond_func = self.known_functions[expr.func.__name__] func = None if isinstance(cond_func, str): func = cond_func else: for cond, func in cond_func: if cond(*expr.args): break if func is not None: try: return func(*[self.parenthesize(item, 0) for item in expr.args]) except TypeError: return "%s(%s)" % (func, self.stringify(expr.args, ", ")) elif hasattr(expr, '_imp_') and isinstance(expr._imp_, Lambda): # inlined function return self._print(expr._imp_(*expr.args)) elif expr.is_Function and self._settings.get('allow_unknown_functions', False): return '%s(%s)' % (self._print(expr.func), ', '.join(map(self._print, expr.args))) else: return self._print_not_supported(expr) _print_Expr = _print_Function def _print_NumberSymbol(self, expr): if self._settings.get("inline", False): return self._print(Float(expr.evalf(self._settings["precision"]))) else: # A Number symbol that is not implemented here or with _printmethod # is registered and evaluated self._number_symbols.add((expr, Float(expr.evalf(self._settings["precision"])))) return str(expr) def _print_Catalan(self, expr): return self._print_NumberSymbol(expr) def _print_EulerGamma(self, expr): return self._print_NumberSymbol(expr) def _print_GoldenRatio(self, expr): return self._print_NumberSymbol(expr) def _print_TribonacciConstant(self, expr): return self._print_NumberSymbol(expr) def _print_Exp1(self, expr): return self._print_NumberSymbol(expr) def _print_Pi(self, expr): return self._print_NumberSymbol(expr) def _print_And(self, expr): PREC = precedence(expr) return (" %s " % self._operators['and']).join(self.parenthesize(a, PREC) for a in sorted(expr.args, key=default_sort_key)) def _print_Or(self, expr): PREC = precedence(expr) return (" %s " % self._operators['or']).join(self.parenthesize(a, PREC) for a in sorted(expr.args, key=default_sort_key)) def _print_Xor(self, expr): if self._operators.get('xor') is None: return self._print_not_supported(expr) PREC = precedence(expr) return (" %s " % self._operators['xor']).join(self.parenthesize(a, PREC) for a in expr.args) def _print_Equivalent(self, expr): if self._operators.get('equivalent') is None: return self._print_not_supported(expr) PREC = precedence(expr) return (" %s " % self._operators['equivalent']).join(self.parenthesize(a, PREC) for a in expr.args) def _print_Not(self, expr): PREC = precedence(expr) return self._operators['not'] + self.parenthesize(expr.args[0], PREC) def _print_Mul(self, expr): prec = precedence(expr) c, e = expr.as_coeff_Mul() if c < 0: expr = _keep_coeff(-c, e) sign = "-" else: sign = "" a = [] # items in the numerator b = [] # items that are in the denominator (if any) pow_paren = [] # Will collect all pow with more than one base element and exp = -1 if self.order not in ('old', 'none'): args = expr.as_ordered_factors() else: # use make_args in case expr was something like -x -> x args = Mul.make_args(expr) # Gather args for numerator/denominator for item in args: if item.is_commutative and item.is_Pow and item.exp.is_Rational and item.exp.is_negative: if item.exp != -1: b.append(Pow(item.base, -item.exp, evaluate=False)) else: if len(item.args[0].args) != 1 and isinstance(item.base, Mul): # To avoid situations like #14160 pow_paren.append(item) b.append(Pow(item.base, -item.exp)) else: a.append(item) a = a or [S.One] a_str = [self.parenthesize(x, prec) for x in a] b_str = [self.parenthesize(x, prec) for x in b] # To parenthesize Pow with exp = -1 and having more than one Symbol for item in pow_paren: if item.base in b: b_str[b.index(item.base)] = "(%s)" % b_str[b.index(item.base)] if len(b) == 0: return sign + '*'.join(a_str) elif len(b) == 1: return sign + '*'.join(a_str) + "/" + b_str[0] else: return sign + '*'.join(a_str) + "/(%s)" % '*'.join(b_str) def _print_not_supported(self, expr): self._not_supported.add(expr) return self.emptyPrinter(expr) # The following can not be simply translated into C or Fortran _print_Basic = _print_not_supported _print_ComplexInfinity = _print_not_supported _print_Derivative = _print_not_supported _print_ExprCondPair = _print_not_supported _print_GeometryEntity = _print_not_supported _print_Infinity = _print_not_supported _print_Integral = _print_not_supported _print_Interval = _print_not_supported _print_AccumulationBounds = _print_not_supported _print_Limit = _print_not_supported _print_Matrix = _print_not_supported _print_ImmutableMatrix = _print_not_supported _print_ImmutableDenseMatrix = _print_not_supported _print_MutableDenseMatrix = _print_not_supported _print_MatrixBase = _print_not_supported _print_DeferredVector = _print_not_supported _print_NaN = _print_not_supported _print_NegativeInfinity = _print_not_supported _print_Normal = _print_not_supported _print_Order = _print_not_supported _print_PDF = _print_not_supported _print_RootOf = _print_not_supported _print_RootsOf = _print_not_supported _print_RootSum = _print_not_supported _print_Sample = _print_not_supported _print_SparseMatrix = _print_not_supported _print_MutableSparseMatrix = _print_not_supported _print_ImmutableSparseMatrix = _print_not_supported _print_Uniform = _print_not_supported _print_Unit = _print_not_supported _print_Wild = _print_not_supported _print_WildFunction = _print_not_supported

5608116685ab73d5e5ff5b2daf52dda3a88c0d16d875cbe7cf0bb56b23011979

"""Tools for manipulating of large commutative expressions. """ from __future__ import print_function, division from sympy.core.add import Add from sympy.core.compatibility import iterable, is_sequence, SYMPY_INTS, range from sympy.core.mul import Mul, _keep_coeff from sympy.core.power import Pow from sympy.core.basic import Basic, preorder_traversal from sympy.core.expr import Expr from sympy.core.sympify import sympify from sympy.core.numbers import Rational, Integer, Number, I from sympy.core.singleton import S from sympy.core.symbol import Dummy from sympy.core.coreerrors import NonCommutativeExpression from sympy.core.containers import Tuple, Dict from sympy.utilities import default_sort_key from sympy.utilities.iterables import (common_prefix, common_suffix, variations, ordered) from collections import defaultdict _eps = Dummy(positive=True) def _isnumber(i): return isinstance(i, (SYMPY_INTS, float)) or i.is_Number def _monotonic_sign(self): """Return the value closest to 0 that ``self`` may have if all symbols are signed and the result is uniformly the same sign for all values of symbols. If a symbol is only signed but not known to be an integer or the result is 0 then a symbol representative of the sign of self will be returned. Otherwise, None is returned if a) the sign could be positive or negative or b) self is not in one of the following forms: - L(x, y, ...) + A: a function linear in all symbols x, y, ... with an additive constant; if A is zero then the function can be a monomial whose sign is monotonic over the range of the variables, e.g. (x + 1)**3 if x is nonnegative. - A/L(x, y, ...) + B: the inverse of a function linear in all symbols x, y, ... that does not have a sign change from positive to negative for any set of values for the variables. - M(x, y, ...) + A: a monomial M whose factors are all signed and a constant, A. - A/M(x, y, ...) + B: the inverse of a monomial and constants A and B. - P(x): a univariate polynomial Examples ======== >>> from sympy.core.exprtools import _monotonic_sign as F >>> from sympy import Dummy, S >>> nn = Dummy(integer=True, nonnegative=True) >>> p = Dummy(integer=True, positive=True) >>> p2 = Dummy(integer=True, positive=True) >>> F(nn + 1) 1 >>> F(p - 1) _nneg >>> F(nn*p + 1) 1 >>> F(p2*p + 1) 2 >>> F(nn - 1) # could be negative, zero or positive """ if not self.is_real: return if (-self).is_Symbol: rv = _monotonic_sign(-self) return rv if rv is None else -rv if not self.is_Add and self.as_numer_denom()[1].is_number: s = self if s.is_prime: if s.is_odd: return S(3) else: return S(2) elif s.is_composite: if s.is_odd: return S(9) else: return S(4) elif s.is_positive: if s.is_even: if s.is_prime is False: return S(4) else: return S(2) elif s.is_integer: return S.One else: return _eps elif s.is_negative: if s.is_even: return S(-2) elif s.is_integer: return S.NegativeOne else: return -_eps if s.is_zero or s.is_nonpositive or s.is_nonnegative: return S.Zero return None # univariate polynomial free = self.free_symbols if len(free) == 1: if self.is_polynomial(): from sympy.polys.polytools import real_roots from sympy.polys.polyroots import roots from sympy.polys.polyerrors import PolynomialError x = free.pop() x0 = _monotonic_sign(x) if x0 == _eps or x0 == -_eps: x0 = S.Zero if x0 is not None: d = self.diff(x) if d.is_number: currentroots = [] else: try: currentroots = real_roots(d) except (PolynomialError, NotImplementedError): currentroots = [r for r in roots(d, x) if r.is_real] y = self.subs(x, x0) if x.is_nonnegative and all(r <= x0 for r in currentroots): if y.is_nonnegative and d.is_positive: if y: return y if y.is_positive else Dummy('pos', positive=True) else: return Dummy('nneg', nonnegative=True) if y.is_nonpositive and d.is_negative: if y: return y if y.is_negative else Dummy('neg', negative=True) else: return Dummy('npos', nonpositive=True) elif x.is_nonpositive and all(r >= x0 for r in currentroots): if y.is_nonnegative and d.is_negative: if y: return Dummy('pos', positive=True) else: return Dummy('nneg', nonnegative=True) if y.is_nonpositive and d.is_positive: if y: return Dummy('neg', negative=True) else: return Dummy('npos', nonpositive=True) else: n, d = self.as_numer_denom() den = None if n.is_number: den = _monotonic_sign(d) elif not d.is_number: if _monotonic_sign(n) is not None: den = _monotonic_sign(d) if den is not None and (den.is_positive or den.is_negative): v = n*den if v.is_positive: return Dummy('pos', positive=True) elif v.is_nonnegative: return Dummy('nneg', nonnegative=True) elif v.is_negative: return Dummy('neg', negative=True) elif v.is_nonpositive: return Dummy('npos', nonpositive=True) return None # multivariate c, a = self.as_coeff_Add() v = None if not a.is_polynomial(): # F/A or A/F where A is a number and F is a signed, rational monomial n, d = a.as_numer_denom() if not (n.is_number or d.is_number): return if ( a.is_Mul or a.is_Pow) and \ a.is_rational and \ all(p.exp.is_Integer for p in a.atoms(Pow) if p.is_Pow) and \ (a.is_positive or a.is_negative): v = S(1) for ai in Mul.make_args(a): if ai.is_number: v *= ai continue reps = {} for x in ai.free_symbols: reps[x] = _monotonic_sign(x) if reps[x] is None: return v *= ai.subs(reps) elif c: # signed linear expression if not any(p for p in a.atoms(Pow) if not p.is_number) and (a.is_nonpositive or a.is_nonnegative): free = list(a.free_symbols) p = {} for i in free: v = _monotonic_sign(i) if v is None: return p[i] = v or (_eps if i.is_nonnegative else -_eps) v = a.xreplace(p) if v is not None: rv = v + c if v.is_nonnegative and rv.is_positive: return rv.subs(_eps, 0) if v.is_nonpositive and rv.is_negative: return rv.subs(_eps, 0) def decompose_power(expr): """ Decompose power into symbolic base and integer exponent. This is strictly only valid if the exponent from which the integer is extracted is itself an integer or the base is positive. These conditions are assumed and not checked here. Examples ======== >>> from sympy.core.exprtools import decompose_power >>> from sympy.abc import x, y >>> decompose_power(x) (x, 1) >>> decompose_power(x**2) (x, 2) >>> decompose_power(x**(2*y)) (x**y, 2) >>> decompose_power(x**(2*y/3)) (x**(y/3), 2) """ base, exp = expr.as_base_exp() if exp.is_Number: if exp.is_Rational: if not exp.is_Integer: base = Pow(base, Rational(1, exp.q)) exp = exp.p else: base, exp = expr, 1 else: exp, tail = exp.as_coeff_Mul(rational=True) if exp is S.NegativeOne: base, exp = Pow(base, tail), -1 elif exp is not S.One: tail = _keep_coeff(Rational(1, exp.q), tail) base, exp = Pow(base, tail), exp.p else: base, exp = expr, 1 return base, exp def decompose_power_rat(expr): """ Decompose power into symbolic base and rational exponent. """ base, exp = expr.as_base_exp() if exp.is_Number: if not exp.is_Rational: base, exp = expr, 1 else: exp, tail = exp.as_coeff_Mul(rational=True) if exp is S.NegativeOne: base, exp = Pow(base, tail), -1 elif exp is not S.One: tail = _keep_coeff(Rational(1, exp.q), tail) base, exp = Pow(base, tail), exp.p else: base, exp = expr, 1 return base, exp class Factors(object): """Efficient representation of ``f_1*f_2*...*f_n``.""" __slots__ = ['factors', 'gens'] def __init__(self, factors=None): # Factors """Initialize Factors from dict or expr. Examples ======== >>> from sympy.core.exprtools import Factors >>> from sympy.abc import x >>> from sympy import I >>> e = 2*x**3 >>> Factors(e) Factors({2: 1, x: 3}) >>> Factors(e.as_powers_dict()) Factors({2: 1, x: 3}) >>> f = _ >>> f.factors # underlying dictionary {2: 1, x: 3} >>> f.gens # base of each factor frozenset({2, x}) >>> Factors(0) Factors({0: 1}) >>> Factors(I) Factors({I: 1}) Notes ===== Although a dictionary can be passed, only minimal checking is performed: powers of -1 and I are made canonical. """ if isinstance(factors, (SYMPY_INTS, float)): factors = S(factors) if isinstance(factors, Factors): factors = factors.factors.copy() elif factors is None or factors is S.One: factors = {} elif factors is S.Zero or factors == 0: factors = {S.Zero: S.One} elif isinstance(factors, Number): n = factors factors = {} if n < 0: factors[S.NegativeOne] = S.One n = -n if n is not S.One: if n.is_Float or n.is_Integer or n is S.Infinity: factors[n] = S.One elif n.is_Rational: # since we're processing Numbers, the denominator is # stored with a negative exponent; all other factors # are left . if n.p != 1: factors[Integer(n.p)] = S.One factors[Integer(n.q)] = S.NegativeOne else: raise ValueError('Expected Float|Rational|Integer, not %s' % n) elif isinstance(factors, Basic) and not factors.args: factors = {factors: S.One} elif isinstance(factors, Expr): c, nc = factors.args_cnc() i = c.count(I) for _ in range(i): c.remove(I) factors = dict(Mul._from_args(c).as_powers_dict()) if i: factors[I] = S.One*i if nc: factors[Mul(*nc, evaluate=False)] = S.One else: factors = factors.copy() # /!\ should be dict-like # tidy up -/+1 and I exponents if Rational handle = [] for k in factors: if k is I or k in (-1, 1): handle.append(k) if handle: i1 = S.One for k in handle: if not _isnumber(factors[k]): continue i1 *= k**factors.pop(k) if i1 is not S.One: for a in i1.args if i1.is_Mul else [i1]: # at worst, -1.0*I*(-1)**e if a is S.NegativeOne: factors[a] = S.One elif a is I: factors[I] = S.One elif a.is_Pow: if S.NegativeOne not in factors: factors[S.NegativeOne] = S.Zero factors[S.NegativeOne] += a.exp elif a == 1: factors[a] = S.One elif a == -1: factors[-a] = S.One factors[S.NegativeOne] = S.One else: raise ValueError('unexpected factor in i1: %s' % a) self.factors = factors try: self.gens = frozenset(factors.keys()) except AttributeError: raise TypeError('expecting Expr or dictionary') def __hash__(self): # Factors keys = tuple(ordered(self.factors.keys())) values = [self.factors[k] for k in keys] return hash((keys, values)) def __repr__(self): # Factors return "Factors({%s})" % ', '.join( ['%s: %s' % (k, v) for k, v in ordered(self.factors.items())]) @property def is_zero(self): # Factors """ >>> from sympy.core.exprtools import Factors >>> Factors(0).is_zero True """ f = self.factors return len(f) == 1 and S.Zero in f @property def is_one(self): # Factors """ >>> from sympy.core.exprtools import Factors >>> Factors(1).is_one True """ return not self.factors def as_expr(self): # Factors """Return the underlying expression. Examples ======== >>> from sympy.core.exprtools import Factors >>> from sympy.abc import x, y >>> Factors((x*y**2).as_powers_dict()).as_expr() x*y**2 """ args = [] for factor, exp in self.factors.items(): if exp != 1: b, e = factor.as_base_exp() if isinstance(exp, int): e = _keep_coeff(Integer(exp), e) elif isinstance(exp, Rational): e = _keep_coeff(exp, e) else: e *= exp args.append(b**e) else: args.append(factor) return Mul(*args) def mul(self, other): # Factors """Return Factors of ``self * other``. Examples ======== >>> from sympy.core.exprtools import Factors >>> from sympy.abc import x, y, z >>> a = Factors((x*y**2).as_powers_dict()) >>> b = Factors((x*y/z).as_powers_dict()) >>> a.mul(b) Factors({x: 2, y: 3, z: -1}) >>> a*b Factors({x: 2, y: 3, z: -1}) """ if not isinstance(other, Factors): other = Factors(other) if any(f.is_zero for f in (self, other)): return Factors(S.Zero) factors = dict(self.factors) for factor, exp in other.factors.items(): if factor in factors: exp = factors[factor] + exp if not exp: del factors[factor] continue factors[factor] = exp return Factors(factors) def normal(self, other): """Return ``self`` and ``other`` with ``gcd`` removed from each. The only differences between this and method ``div`` is that this is 1) optimized for the case when there are few factors in common and 2) this does not raise an error if ``other`` is zero. See Also ======== div """ if not isinstance(other, Factors): other = Factors(other) if other.is_zero: return (Factors(), Factors(S.Zero)) if self.is_zero: return (Factors(S.Zero), Factors()) self_factors = dict(self.factors) other_factors = dict(other.factors) for factor, self_exp in self.factors.items(): try: other_exp = other.factors[factor] except KeyError: continue exp = self_exp - other_exp if not exp: del self_factors[factor] del other_factors[factor] elif _isnumber(exp): if exp > 0: self_factors[factor] = exp del other_factors[factor] else: del self_factors[factor] other_factors[factor] = -exp else: r = self_exp.extract_additively(other_exp) if r is not None: if r: self_factors[factor] = r del other_factors[factor] else: # should be handled already del self_factors[factor] del other_factors[factor] else: sc, sa = self_exp.as_coeff_Add() if sc: oc, oa = other_exp.as_coeff_Add() diff = sc - oc if diff > 0: self_factors[factor] -= oc other_exp = oa elif diff < 0: self_factors[factor] -= sc other_factors[factor] -= sc other_exp = oa - diff else: self_factors[factor] = sa other_exp = oa if other_exp: other_factors[factor] = other_exp else: del other_factors[factor] return Factors(self_factors), Factors(other_factors) def div(self, other): # Factors """Return ``self`` and ``other`` with ``gcd`` removed from each. This is optimized for the case when there are many factors in common. Examples ======== >>> from sympy.core.exprtools import Factors >>> from sympy.abc import x, y, z >>> from sympy import S >>> a = Factors((x*y**2).as_powers_dict()) >>> a.div(a) (Factors({}), Factors({})) >>> a.div(x*z) (Factors({y: 2}), Factors({z: 1})) The ``/`` operator only gives ``quo``: >>> a/x Factors({y: 2}) Factors treats its factors as though they are all in the numerator, so if you violate this assumption the results will be correct but will not strictly correspond to the numerator and denominator of the ratio: >>> a.div(x/z) (Factors({y: 2}), Factors({z: -1})) Factors is also naive about bases: it does not attempt any denesting of Rational-base terms, for example the following does not become 2**(2*x)/2. >>> Factors(2**(2*x + 2)).div(S(8)) (Factors({2: 2*x + 2}), Factors({8: 1})) factor_terms can clean up such Rational-bases powers: >>> from sympy.core.exprtools import factor_terms >>> n, d = Factors(2**(2*x + 2)).div(S(8)) >>> n.as_expr()/d.as_expr() 2**(2*x + 2)/8 >>> factor_terms(_) 2**(2*x)/2 """ quo, rem = dict(self.factors), {} if not isinstance(other, Factors): other = Factors(other) if other.is_zero: raise ZeroDivisionError if self.is_zero: return (Factors(S.Zero), Factors()) for factor, exp in other.factors.items(): if factor in quo: d = quo[factor] - exp if _isnumber(d): if d <= 0: del quo[factor] if d >= 0: if d: quo[factor] = d continue exp = -d else: r = quo[factor].extract_additively(exp) if r is not None: if r: quo[factor] = r else: # should be handled already del quo[factor] else: other_exp = exp sc, sa = quo[factor].as_coeff_Add() if sc: oc, oa = other_exp.as_coeff_Add() diff = sc - oc if diff > 0: quo[factor] -= oc other_exp = oa elif diff < 0: quo[factor] -= sc other_exp = oa - diff else: quo[factor] = sa other_exp = oa if other_exp: rem[factor] = other_exp else: assert factor not in rem continue rem[factor] = exp return Factors(quo), Factors(rem) def quo(self, other): # Factors """Return numerator Factor of ``self / other``. Examples ======== >>> from sympy.core.exprtools import Factors >>> from sympy.abc import x, y, z >>> a = Factors((x*y**2).as_powers_dict()) >>> b = Factors((x*y/z).as_powers_dict()) >>> a.quo(b) # same as a/b Factors({y: 1}) """ return self.div(other)[0] def rem(self, other): # Factors """Return denominator Factors of ``self / other``. Examples ======== >>> from sympy.core.exprtools import Factors >>> from sympy.abc import x, y, z >>> a = Factors((x*y**2).as_powers_dict()) >>> b = Factors((x*y/z).as_powers_dict()) >>> a.rem(b) Factors({z: -1}) >>> a.rem(a) Factors({}) """ return self.div(other)[1] def pow(self, other): # Factors """Return self raised to a non-negative integer power. Examples ======== >>> from sympy.core.exprtools import Factors >>> from sympy.abc import x, y >>> a = Factors((x*y**2).as_powers_dict()) >>> a**2 Factors({x: 2, y: 4}) """ if isinstance(other, Factors): other = other.as_expr() if other.is_Integer: other = int(other) if isinstance(other, SYMPY_INTS) and other >= 0: factors = {} if other: for factor, exp in self.factors.items(): factors[factor] = exp*other return Factors(factors) else: raise ValueError("expected non-negative integer, got %s" % other) def gcd(self, other): # Factors """Return Factors of ``gcd(self, other)``. The keys are the intersection of factors with the minimum exponent for each factor. Examples ======== >>> from sympy.core.exprtools import Factors >>> from sympy.abc import x, y, z >>> a = Factors((x*y**2).as_powers_dict()) >>> b = Factors((x*y/z).as_powers_dict()) >>> a.gcd(b) Factors({x: 1, y: 1}) """ if not isinstance(other, Factors): other = Factors(other) if other.is_zero: return Factors(self.factors) factors = {} for factor, exp in self.factors.items(): factor, exp = sympify(factor), sympify(exp) if factor in other.factors: lt = (exp - other.factors[factor]).is_negative if lt == True: factors[factor] = exp elif lt == False: factors[factor] = other.factors[factor] return Factors(factors) def lcm(self, other): # Factors """Return Factors of ``lcm(self, other)`` which are the union of factors with the maximum exponent for each factor. Examples ======== >>> from sympy.core.exprtools import Factors >>> from sympy.abc import x, y, z >>> a = Factors((x*y**2).as_powers_dict()) >>> b = Factors((x*y/z).as_powers_dict()) >>> a.lcm(b) Factors({x: 1, y: 2, z: -1}) """ if not isinstance(other, Factors): other = Factors(other) if any(f.is_zero for f in (self, other)): return Factors(S.Zero) factors = dict(self.factors) for factor, exp in other.factors.items(): if factor in factors: exp = max(exp, factors[factor]) factors[factor] = exp return Factors(factors) def __mul__(self, other): # Factors return self.mul(other) def __divmod__(self, other): # Factors return self.div(other) def __div__(self, other): # Factors return self.quo(other) __truediv__ = __div__ def __mod__(self, other): # Factors return self.rem(other) def __pow__(self, other): # Factors return self.pow(other) def __eq__(self, other): # Factors if not isinstance(other, Factors): other = Factors(other) return self.factors == other.factors def __ne__(self, other): # Factors return not self == other class Term(object): """Efficient representation of ``coeff*(numer/denom)``. """ __slots__ = ['coeff', 'numer', 'denom'] def __init__(self, term, numer=None, denom=None): # Term if numer is None and denom is None: if not term.is_commutative: raise NonCommutativeExpression( 'commutative expression expected') coeff, factors = term.as_coeff_mul() numer, denom = defaultdict(int), defaultdict(int) for factor in factors: base, exp = decompose_power(factor) if base.is_Add: cont, base = base.primitive() coeff *= cont**exp if exp > 0: numer[base] += exp else: denom[base] += -exp numer = Factors(numer) denom = Factors(denom) else: coeff = term if numer is None: numer = Factors() if denom is None: denom = Factors() self.coeff = coeff self.numer = numer self.denom = denom def __hash__(self): # Term return hash((self.coeff, self.numer, self.denom)) def __repr__(self): # Term return "Term(%s, %s, %s)" % (self.coeff, self.numer, self.denom) def as_expr(self): # Term return self.coeff*(self.numer.as_expr()/self.denom.as_expr()) def mul(self, other): # Term coeff = self.coeff*other.coeff numer = self.numer.mul(other.numer) denom = self.denom.mul(other.denom) numer, denom = numer.normal(denom) return Term(coeff, numer, denom) def inv(self): # Term return Term(1/self.coeff, self.denom, self.numer) def quo(self, other): # Term return self.mul(other.inv()) def pow(self, other): # Term if other < 0: return self.inv().pow(-other) else: return Term(self.coeff ** other, self.numer.pow(other), self.denom.pow(other)) def gcd(self, other): # Term return Term(self.coeff.gcd(other.coeff), self.numer.gcd(other.numer), self.denom.gcd(other.denom)) def lcm(self, other): # Term return Term(self.coeff.lcm(other.coeff), self.numer.lcm(other.numer), self.denom.lcm(other.denom)) def __mul__(self, other): # Term if isinstance(other, Term): return self.mul(other) else: return NotImplemented def __div__(self, other): # Term if isinstance(other, Term): return self.quo(other) else: return NotImplemented __truediv__ = __div__ def __pow__(self, other): # Term if isinstance(other, SYMPY_INTS): return self.pow(other) else: return NotImplemented def __eq__(self, other): # Term return (self.coeff == other.coeff and self.numer == other.numer and self.denom == other.denom) def __ne__(self, other): # Term return not self == other def _gcd_terms(terms, isprimitive=False, fraction=True): """Helper function for :func:`gcd_terms`. If ``isprimitive`` is True then the call to primitive for an Add will be skipped. This is useful when the content has already been extrated. If ``fraction`` is True then the expression will appear over a common denominator, the lcm of all term denominators. """ if isinstance(terms, Basic) and not isinstance(terms, Tuple): terms = Add.make_args(terms) terms = list(map(Term, [t for t in terms if t])) # there is some simplification that may happen if we leave this # here rather than duplicate it before the mapping of Term onto # the terms if len(terms) == 0: return S.Zero, S.Zero, S.One if len(terms) == 1: cont = terms[0].coeff numer = terms[0].numer.as_expr() denom = terms[0].denom.as_expr() else: cont = terms[0] for term in terms[1:]: cont = cont.gcd(term) for i, term in enumerate(terms): terms[i] = term.quo(cont) if fraction: denom = terms[0].denom for term in terms[1:]: denom = denom.lcm(term.denom) numers = [] for term in terms: numer = term.numer.mul(denom.quo(term.denom)) numers.append(term.coeff*numer.as_expr()) else: numers = [t.as_expr() for t in terms] denom = Term(S(1)).numer cont = cont.as_expr() numer = Add(*numers) denom = denom.as_expr() if not isprimitive and numer.is_Add: _cont, numer = numer.primitive() cont *= _cont return cont, numer, denom def gcd_terms(terms, isprimitive=False, clear=True, fraction=True): """Compute the GCD of ``terms`` and put them together. ``terms`` can be an expression or a non-Basic sequence of expressions which will be handled as though they are terms from a sum. If ``isprimitive`` is True the _gcd_terms will not run the primitive method on the terms. ``clear`` controls the removal of integers from the denominator of an Add expression. When True (default), all numerical denominator will be cleared; when False the denominators will be cleared only if all terms had numerical denominators other than 1. ``fraction``, when True (default), will put the expression over a common denominator. Examples ======== >>> from sympy.core import gcd_terms >>> from sympy.abc import x, y >>> gcd_terms((x + 1)**2*y + (x + 1)*y**2) y*(x + 1)*(x + y + 1) >>> gcd_terms(x/2 + 1) (x + 2)/2 >>> gcd_terms(x/2 + 1, clear=False) x/2 + 1 >>> gcd_terms(x/2 + y/2, clear=False) (x + y)/2 >>> gcd_terms(x/2 + 1/x) (x**2 + 2)/(2*x) >>> gcd_terms(x/2 + 1/x, fraction=False) (x + 2/x)/2 >>> gcd_terms(x/2 + 1/x, fraction=False, clear=False) x/2 + 1/x >>> gcd_terms(x/2/y + 1/x/y) (x**2 + 2)/(2*x*y) >>> gcd_terms(x/2/y + 1/x/y, clear=False) (x**2/2 + 1)/(x*y) >>> gcd_terms(x/2/y + 1/x/y, clear=False, fraction=False) (x/2 + 1/x)/y The ``clear`` flag was ignored in this case because the returned expression was a rational expression, not a simple sum. See Also ======== factor_terms, sympy.polys.polytools.terms_gcd """ def mask(terms): """replace nc portions of each term with a unique Dummy symbols and return the replacements to restore them""" args = [(a, []) if a.is_commutative else a.args_cnc() for a in terms] reps = [] for i, (c, nc) in enumerate(args): if nc: nc = Mul._from_args(nc) d = Dummy() reps.append((d, nc)) c.append(d) args[i] = Mul._from_args(c) else: args[i] = c return args, dict(reps) isadd = isinstance(terms, Add) addlike = isadd or not isinstance(terms, Basic) and \ is_sequence(terms, include=set) and \ not isinstance(terms, Dict) if addlike: if isadd: # i.e. an Add terms = list(terms.args) else: terms = sympify(terms) terms, reps = mask(terms) cont, numer, denom = _gcd_terms(terms, isprimitive, fraction) numer = numer.xreplace(reps) coeff, factors = cont.as_coeff_Mul() if not clear: c, _coeff = coeff.as_coeff_Mul() if not c.is_Integer and not clear and numer.is_Add: n, d = c.as_numer_denom() _numer = numer/d if any(a.as_coeff_Mul()[0].is_Integer for a in _numer.args): numer = _numer coeff = n*_coeff return _keep_coeff(coeff, factors*numer/denom, clear=clear) if not isinstance(terms, Basic): return terms if terms.is_Atom: return terms if terms.is_Mul: c, args = terms.as_coeff_mul() return _keep_coeff(c, Mul(*[gcd_terms(i, isprimitive, clear, fraction) for i in args]), clear=clear) def handle(a): # don't treat internal args like terms of an Add if not isinstance(a, Expr): if isinstance(a, Basic): return a.func(*[handle(i) for i in a.args]) return type(a)([handle(i) for i in a]) return gcd_terms(a, isprimitive, clear, fraction) if isinstance(terms, Dict): return Dict(*[(k, handle(v)) for k, v in terms.args]) return terms.func(*[handle(i) for i in terms.args]) def factor_terms(expr, radical=False, clear=False, fraction=False, sign=True): """Remove common factors from terms in all arguments without changing the underlying structure of the expr. No expansion or simplification (and no processing of non-commutatives) is performed. If radical=True then a radical common to all terms will be factored out of any Add sub-expressions of the expr. If clear=False (default) then coefficients will not be separated from a single Add if they can be distributed to leave one or more terms with integer coefficients. If fraction=True (default is False) then a common denominator will be constructed for the expression. If sign=True (default) then even if the only factor in common is a -1, it will be factored out of the expression. Examples ======== >>> from sympy import factor_terms, Symbol >>> from sympy.abc import x, y >>> factor_terms(x + x*(2 + 4*y)**3) x*(8*(2*y + 1)**3 + 1) >>> A = Symbol('A', commutative=False) >>> factor_terms(x*A + x*A + x*y*A) x*(y*A + 2*A) When ``clear`` is False, a rational will only be factored out of an Add expression if all terms of the Add have coefficients that are fractions: >>> factor_terms(x/2 + 1, clear=False) x/2 + 1 >>> factor_terms(x/2 + 1, clear=True) (x + 2)/2 If a -1 is all that can be factored out, to *not* factor it out, the flag ``sign`` must be False: >>> factor_terms(-x - y) -(x + y) >>> factor_terms(-x - y, sign=False) -x - y >>> factor_terms(-2*x - 2*y, sign=False) -2*(x + y) See Also ======== gcd_terms, sympy.polys.polytools.terms_gcd """ def do(expr): from sympy.concrete.summations import Sum from sympy.simplify.simplify import factor_sum is_iterable = iterable(expr) if not isinstance(expr, Basic) or expr.is_Atom: if is_iterable: return type(expr)([do(i) for i in expr]) return expr if expr.is_Pow or expr.is_Function or \ is_iterable or not hasattr(expr, 'args_cnc'): args = expr.args newargs = tuple([do(i) for i in args]) if newargs == args: return expr return expr.func(*newargs) if isinstance(expr, Sum): return factor_sum(expr, radical=radical, clear=clear, fraction=fraction, sign=sign) cont, p = expr.as_content_primitive(radical=radical, clear=clear) if p.is_Add: list_args = [do(a) for a in Add.make_args(p)] # get a common negative (if there) which gcd_terms does not remove if all(a.as_coeff_Mul()[0].extract_multiplicatively(-1) is not None for a in list_args): cont = -cont list_args = [-a for a in list_args] # watch out for exp(-(x+2)) which gcd_terms will change to exp(-x-2) special = {} for i, a in enumerate(list_args): b, e = a.as_base_exp() if e.is_Mul and e != Mul(*e.args): list_args[i] = Dummy() special[list_args[i]] = a # rebuild p not worrying about the order which gcd_terms will fix p = Add._from_args(list_args) p = gcd_terms(p, isprimitive=True, clear=clear, fraction=fraction).xreplace(special) elif p.args: p = p.func( *[do(a) for a in p.args]) rv = _keep_coeff(cont, p, clear=clear, sign=sign) return rv expr = sympify(expr) return do(expr) def _mask_nc(eq, name=None): """ Return ``eq`` with non-commutative objects replaced with Dummy symbols. A dictionary that can be used to restore the original values is returned: if it is None, the expression is noncommutative and cannot be made commutative. The third value returned is a list of any non-commutative symbols that appear in the returned equation. ``name``, if given, is the name that will be used with numered Dummy variables that will replace the non-commutative objects and is mainly used for doctesting purposes. Notes ===== All non-commutative objects other than Symbols are replaced with a non-commutative Symbol. Identical objects will be identified by identical symbols. If there is only 1 non-commutative object in an expression it will be replaced with a commutative symbol. Otherwise, the non-commutative entities are retained and the calling routine should handle replacements in this case since some care must be taken to keep track of the ordering of symbols when they occur within Muls. Examples ======== >>> from sympy.physics.secondquant import Commutator, NO, F, Fd >>> from sympy import symbols, Mul >>> from sympy.core.exprtools import _mask_nc >>> from sympy.abc import x, y >>> A, B, C = symbols('A,B,C', commutative=False) One nc-symbol: >>> _mask_nc(A**2 - x**2, 'd') (_d0**2 - x**2, {_d0: A}, []) Multiple nc-symbols: >>> _mask_nc(A**2 - B**2, 'd') (A**2 - B**2, {}, [A, B]) An nc-object with nc-symbols but no others outside of it: >>> _mask_nc(1 + x*Commutator(A, B), 'd') (_d0*x + 1, {_d0: Commutator(A, B)}, []) >>> _mask_nc(NO(Fd(x)*F(y)), 'd') (_d0, {_d0: NO(CreateFermion(x)*AnnihilateFermion(y))}, []) Multiple nc-objects: >>> eq = x*Commutator(A, B) + x*Commutator(A, C)*Commutator(A, B) >>> _mask_nc(eq, 'd') (x*_d0 + x*_d1*_d0, {_d0: Commutator(A, B), _d1: Commutator(A, C)}, [_d0, _d1]) Multiple nc-objects and nc-symbols: >>> eq = A*Commutator(A, B) + B*Commutator(A, C) >>> _mask_nc(eq, 'd') (A*_d0 + B*_d1, {_d0: Commutator(A, B), _d1: Commutator(A, C)}, [_d0, _d1, A, B]) If there is an object that: - doesn't contain nc-symbols - but has arguments which derive from Basic, not Expr - and doesn't define an _eval_is_commutative routine then it will give False (or None?) for the is_commutative test. Such objects are also removed by this routine: >>> from sympy import Basic >>> eq = (1 + Mul(Basic(), Basic(), evaluate=False)) >>> eq.is_commutative False >>> _mask_nc(eq, 'd') (_d0**2 + 1, {_d0: Basic()}, []) """ name = name or 'mask' # Make Dummy() append sequential numbers to the name def numbered_names(): i = 0 while True: yield name + str(i) i += 1 names = numbered_names() def Dummy(*args, **kwargs): from sympy import Dummy return Dummy(next(names), *args, **kwargs) expr = eq if expr.is_commutative: return eq, {}, [] # identify nc-objects; symbols and other rep = [] nc_obj = set() nc_syms = set() pot = preorder_traversal(expr, keys=default_sort_key) for i, a in enumerate(pot): if any(a == r[0] for r in rep): pot.skip() elif not a.is_commutative: if a.is_symbol: nc_syms.add(a) pot.skip() elif not (a.is_Add or a.is_Mul or a.is_Pow): nc_obj.add(a) pot.skip() # If there is only one nc symbol or object, it can be factored regularly # but polys is going to complain, so replace it with a Dummy. if len(nc_obj) == 1 and not nc_syms: rep.append((nc_obj.pop(), Dummy())) elif len(nc_syms) == 1 and not nc_obj: rep.append((nc_syms.pop(), Dummy())) # Any remaining nc-objects will be replaced with an nc-Dummy and # identified as an nc-Symbol to watch out for nc_obj = sorted(nc_obj, key=default_sort_key) for n in nc_obj: nc = Dummy(commutative=False) rep.append((n, nc)) nc_syms.add(nc) expr = expr.subs(rep) nc_syms = list(nc_syms) nc_syms.sort(key=default_sort_key) return expr, {v: k for k, v in rep}, nc_syms def factor_nc(expr): """Return the factored form of ``expr`` while handling non-commutative expressions. Examples ======== >>> from sympy.core.exprtools import factor_nc >>> from sympy import Symbol >>> from sympy.abc import x >>> A = Symbol('A', commutative=False) >>> B = Symbol('B', commutative=False) >>> factor_nc((x**2 + 2*A*x + A**2).expand()) (x + A)**2 >>> factor_nc(((x + A)*(x + B)).expand()) (x + A)*(x + B) """ from sympy.simplify.simplify import powsimp from sympy.polys import gcd, factor def _pemexpand(expr): "Expand with the minimal set of hints necessary to check the result." return expr.expand(deep=True, mul=True, power_exp=True, power_base=False, basic=False, multinomial=True, log=False) expr = sympify(expr) if not isinstance(expr, Expr) or not expr.args: return expr if not expr.is_Add: return expr.func(*[factor_nc(a) for a in expr.args]) expr, rep, nc_symbols = _mask_nc(expr) if rep: return factor(expr).subs(rep) else: args = [a.args_cnc() for a in Add.make_args(expr)] c = g = l = r = S.One hit = False # find any commutative gcd term for i, a in enumerate(args): if i == 0: c = Mul._from_args(a[0]) elif a[0]: c = gcd(c, Mul._from_args(a[0])) else: c = S.One if c is not S.One: hit = True c, g = c.as_coeff_Mul() if g is not S.One: for i, (cc, _) in enumerate(args): cc = list(Mul.make_args(Mul._from_args(list(cc))/g)) args[i][0] = cc for i, (cc, _) in enumerate(args): cc[0] = cc[0]/c args[i][0] = cc # find any noncommutative common prefix for i, a in enumerate(args): if i == 0: n = a[1][:] else: n = common_prefix(n, a[1]) if not n: # is there a power that can be extracted? if not args[0][1]: break b, e = args[0][1][0].as_base_exp() ok = False if e.is_Integer: for t in args: if not t[1]: break bt, et = t[1][0].as_base_exp() if et.is_Integer and bt == b: e = min(e, et) else: break else: ok = hit = True l = b**e il = b**-e for i, a in enumerate(args): args[i][1][0] = il*args[i][1][0] break if not ok: break else: hit = True lenn = len(n) l = Mul(*n) for i, a in enumerate(args): args[i][1] = args[i][1][lenn:] # find any noncommutative common suffix for i, a in enumerate(args): if i == 0: n = a[1][:] else: n = common_suffix(n, a[1]) if not n: # is there a power that can be extracted? if not args[0][1]: break b, e = args[0][1][-1].as_base_exp() ok = False if e.is_Integer: for t in args: if not t[1]: break bt, et = t[1][-1].as_base_exp() if et.is_Integer and bt == b: e = min(e, et) else: break else: ok = hit = True r = b**e il = b**-e for i, a in enumerate(args): args[i][1][-1] = args[i][1][-1]*il break if not ok: break else: hit = True lenn = len(n) r = Mul(*n) for i, a in enumerate(args): args[i][1] = a[1][:len(a[1]) - lenn] if hit: mid = Add(*[Mul(*cc)*Mul(*nc) for cc, nc in args]) else: mid = expr # sort the symbols so the Dummys would appear in the same # order as the original symbols, otherwise you may introduce # a factor of -1, e.g. A**2 - B**2) -- {A:y, B:x} --> y**2 - x**2 # and the former factors into two terms, (A - B)*(A + B) while the # latter factors into 3 terms, (-1)*(x - y)*(x + y) rep1 = [(n, Dummy()) for n in sorted(nc_symbols, key=default_sort_key)] unrep1 = [(v, k) for k, v in rep1] unrep1.reverse() new_mid, r2, _ = _mask_nc(mid.subs(rep1)) new_mid = powsimp(factor(new_mid)) new_mid = new_mid.subs(r2).subs(unrep1) if new_mid.is_Pow: return _keep_coeff(c, g*l*new_mid*r) if new_mid.is_Mul: # XXX TODO there should be a way to inspect what order the terms # must be in and just select the plausible ordering without # checking permutations cfac = [] ncfac = [] for f in new_mid.args: if f.is_commutative: cfac.append(f) else: b, e = f.as_base_exp() if e.is_Integer: ncfac.extend([b]*e) else: ncfac.append(f) pre_mid = g*Mul(*cfac)*l target = _pemexpand(expr/c) for s in variations(ncfac, len(ncfac)): ok = pre_mid*Mul(*s)*r if _pemexpand(ok) == target: return _keep_coeff(c, ok) # mid was an Add that didn't factor successfully return _keep_coeff(c, g*l*mid*r)

9b13f65ecfbdb6b3d6100fcc4bb6342f096d63db8010222ada8bb4cbb14cfcd9

""" There are three types of functions implemented in SymPy: 1) defined functions (in the sense that they can be evaluated) like exp or sin; they have a name and a body: f = exp 2) undefined function which have a name but no body. Undefined functions can be defined using a Function class as follows: f = Function('f') (the result will be a Function instance) 3) anonymous function (or lambda function) which have a body (defined with dummy variables) but have no name: f = Lambda(x, exp(x)*x) f = Lambda((x, y), exp(x)*y) The fourth type of functions are composites, like (sin + cos)(x); these work in SymPy core, but are not yet part of SymPy. Examples ======== >>> import sympy >>> f = sympy.Function("f") >>> from sympy.abc import x >>> f(x) f(x) >>> print(sympy.srepr(f(x).func)) Function('f') >>> f(x).args (x,) """ from __future__ import print_function, division from .add import Add from .assumptions import ManagedProperties, _assume_defined from .basic import Basic, _atomic from .cache import cacheit from .compatibility import iterable, is_sequence, as_int, ordered, Iterable from .decorators import _sympifyit from .expr import Expr, AtomicExpr from .numbers import Rational, Float from .operations import LatticeOp from .rules import Transform from .singleton import S from .sympify import sympify from sympy.core.containers import Tuple, Dict from sympy.core.logic import fuzzy_and from sympy.core.compatibility import string_types, with_metaclass, range from sympy.utilities import default_sort_key from sympy.utilities.misc import filldedent from sympy.utilities.iterables import has_dups from sympy.core.evaluate import global_evaluate import sys import mpmath import mpmath.libmp as mlib import inspect from collections import Counter def _coeff_isneg(a): """Return True if the leading Number is negative. Examples ======== >>> from sympy.core.function import _coeff_isneg >>> from sympy import S, Symbol, oo, pi >>> _coeff_isneg(-3*pi) True >>> _coeff_isneg(S(3)) False >>> _coeff_isneg(-oo) True >>> _coeff_isneg(Symbol('n', negative=True)) # coeff is 1 False For matrix expressions: >>> from sympy import MatrixSymbol, sqrt >>> A = MatrixSymbol("A", 3, 3) >>> _coeff_isneg(-sqrt(2)*A) True >>> _coeff_isneg(sqrt(2)*A) False """ if a.is_MatMul: a = a.args[0] if a.is_Mul: a = a.args[0] return a.is_Number and a.is_negative class PoleError(Exception): pass class ArgumentIndexError(ValueError): def __str__(self): return ("Invalid operation with argument number %s for Function %s" % (self.args[1], self.args[0])) def _getnargs(cls): if hasattr(cls, 'eval'): if sys.version_info < (3, ): return _getnargs_old(cls.eval) else: return _getnargs_new(cls.eval) else: return None def _getnargs_old(eval_): evalargspec = inspect.getargspec(eval_) if evalargspec.varargs: return None else: evalargs = len(evalargspec.args) - 1 # subtract 1 for cls if evalargspec.defaults: # if there are default args then they are optional; the # fewest args will occur when all defaults are used and # the most when none are used (i.e. all args are given) return tuple(range( evalargs - len(evalargspec.defaults), evalargs + 1)) return evalargs def _getnargs_new(eval_): parameters = inspect.signature(eval_).parameters.items() if [p for n,p in parameters if p.kind == p.VAR_POSITIONAL]: return None else: p_or_k = [p for n,p in parameters if p.kind == p.POSITIONAL_OR_KEYWORD] num_no_default = len(list(filter(lambda p:p.default == p.empty, p_or_k))) num_with_default = len(list(filter(lambda p:p.default != p.empty, p_or_k))) if not num_with_default: return num_no_default return tuple(range(num_no_default, num_no_default+num_with_default+1)) class FunctionClass(ManagedProperties): """ Base class for function classes. FunctionClass is a subclass of type. Use Function('<function name>' [ , signature ]) to create undefined function classes. """ _new = type.__new__ def __init__(cls, *args, **kwargs): # honor kwarg value or class-defined value before using # the number of arguments in the eval function (if present) nargs = kwargs.pop('nargs', cls.__dict__.get('nargs', _getnargs(cls))) # Canonicalize nargs here; change to set in nargs. if is_sequence(nargs): if not nargs: raise ValueError(filldedent(''' Incorrectly specified nargs as %s: if there are no arguments, it should be `nargs = 0`; if there are any number of arguments, it should be `nargs = None`''' % str(nargs))) nargs = tuple(ordered(set(nargs))) elif nargs is not None: nargs = (as_int(nargs),) cls._nargs = nargs super(FunctionClass, cls).__init__(*args, **kwargs) @property def __signature__(self): """ Allow Python 3's inspect.signature to give a useful signature for Function subclasses. """ # Python 3 only, but backports (like the one in IPython) still might # call this. try: from inspect import signature except ImportError: return None # TODO: Look at nargs return signature(self.eval) @property def free_symbols(self): return set() @property def xreplace(self): # Function needs args so we define a property that returns # a function that takes args...and then use that function # to return the right value return lambda rule, **_: rule.get(self, self) @property def nargs(self): """Return a set of the allowed number of arguments for the function. Examples ======== >>> from sympy.core.function import Function >>> from sympy.abc import x, y >>> f = Function('f') If the function can take any number of arguments, the set of whole numbers is returned: >>> Function('f').nargs Naturals0 If the function was initialized to accept one or more arguments, a corresponding set will be returned: >>> Function('f', nargs=1).nargs {1} >>> Function('f', nargs=(2, 1)).nargs {1, 2} The undefined function, after application, also has the nargs attribute; the actual number of arguments is always available by checking the ``args`` attribute: >>> f = Function('f') >>> f(1).nargs Naturals0 >>> len(f(1).args) 1 """ from sympy.sets.sets import FiniteSet # XXX it would be nice to handle this in __init__ but there are import # problems with trying to import FiniteSet there return FiniteSet(*self._nargs) if self._nargs else S.Naturals0 def __repr__(cls): return cls.__name__ class Application(with_metaclass(FunctionClass, Basic)): """ Base class for applied functions. Instances of Application represent the result of applying an application of any type to any object. """ is_Function = True @cacheit def __new__(cls, *args, **options): from sympy.sets.fancysets import Naturals0 from sympy.sets.sets import FiniteSet args = list(map(sympify, args)) evaluate = options.pop('evaluate', global_evaluate[0]) # WildFunction (and anything else like it) may have nargs defined # and we throw that value away here options.pop('nargs', None) if options: raise ValueError("Unknown options: %s" % options) if evaluate: evaluated = cls.eval(*args) if evaluated is not None: return evaluated obj = super(Application, cls).__new__(cls, *args, **options) # make nargs uniform here try: # things passing through here: # - functions subclassed from Function (e.g. myfunc(1).nargs) # - functions like cos(1).nargs # - AppliedUndef with given nargs like Function('f', nargs=1)(1).nargs # Canonicalize nargs here if is_sequence(obj.nargs): nargs = tuple(ordered(set(obj.nargs))) elif obj.nargs is not None: nargs = (as_int(obj.nargs),) else: nargs = None except AttributeError: # things passing through here: # - WildFunction('f').nargs # - AppliedUndef with no nargs like Function('f')(1).nargs nargs = obj._nargs # note the underscore here # convert to FiniteSet obj.nargs = FiniteSet(*nargs) if nargs else Naturals0() return obj @classmethod def eval(cls, *args): """ Returns a canonical form of cls applied to arguments args. The eval() method is called when the class cls is about to be instantiated and it should return either some simplified instance (possible of some other class), or if the class cls should be unmodified, return None. Examples of eval() for the function "sign" --------------------------------------------- .. code-block:: python @classmethod def eval(cls, arg): if arg is S.NaN: return S.NaN if arg is S.Zero: return S.Zero if arg.is_positive: return S.One if arg.is_negative: return S.NegativeOne if isinstance(arg, Mul): coeff, terms = arg.as_coeff_Mul(rational=True) if coeff is not S.One: return cls(coeff) * cls(terms) """ return @property def func(self): return self.__class__ def _eval_subs(self, old, new): if (old.is_Function and new.is_Function and callable(old) and callable(new) and old == self.func and len(self.args) in new.nargs): return new(*[i._subs(old, new) for i in self.args]) class Function(Application, Expr): """ Base class for applied mathematical functions. It also serves as a constructor for undefined function classes. Examples ======== First example shows how to use Function as a constructor for undefined function classes: >>> from sympy import Function, Symbol >>> x = Symbol('x') >>> f = Function('f') >>> g = Function('g')(x) >>> f f >>> f(x) f(x) >>> g g(x) >>> f(x).diff(x) Derivative(f(x), x) >>> g.diff(x) Derivative(g(x), x) Assumptions can be passed to Function. >>> f_real = Function('f', real=True) >>> f_real(x).is_real True Note that assumptions on a function are unrelated to the assumptions on the variable it is called on. If you want to add a relationship, subclass Function and define the appropriate ``_eval_is_assumption`` methods. In the following example Function is used as a base class for ``my_func`` that represents a mathematical function *my_func*. Suppose that it is well known, that *my_func(0)* is *1* and *my_func* at infinity goes to *0*, so we want those two simplifications to occur automatically. Suppose also that *my_func(x)* is real exactly when *x* is real. Here is an implementation that honours those requirements: >>> from sympy import Function, S, oo, I, sin >>> class my_func(Function): ... ... @classmethod ... def eval(cls, x): ... if x.is_Number: ... if x is S.Zero: ... return S.One ... elif x is S.Infinity: ... return S.Zero ... ... def _eval_is_real(self): ... return self.args[0].is_real ... >>> x = S('x') >>> my_func(0) + sin(0) 1 >>> my_func(oo) 0 >>> my_func(3.54).n() # Not yet implemented for my_func. my_func(3.54) >>> my_func(I).is_real False In order for ``my_func`` to become useful, several other methods would need to be implemented. See source code of some of the already implemented functions for more complete examples. Also, if the function can take more than one argument, then ``nargs`` must be defined, e.g. if ``my_func`` can take one or two arguments then, >>> class my_func(Function): ... nargs = (1, 2) ... >>> """ @property def _diff_wrt(self): return False @cacheit def __new__(cls, *args, **options): # Handle calls like Function('f') if cls is Function: return UndefinedFunction(*args, **options) n = len(args) if n not in cls.nargs: # XXX: exception message must be in exactly this format to # make it work with NumPy's functions like vectorize(). See, # for example, https://github.com/numpy/numpy/issues/1697. # The ideal solution would be just to attach metadata to # the exception and change NumPy to take advantage of this. temp = ('%(name)s takes %(qual)s %(args)s ' 'argument%(plural)s (%(given)s given)') raise TypeError(temp % { 'name': cls, 'qual': 'exactly' if len(cls.nargs) == 1 else 'at least', 'args': min(cls.nargs), 'plural': 's'*(min(cls.nargs) != 1), 'given': n}) evaluate = options.get('evaluate', global_evaluate[0]) result = super(Function, cls).__new__(cls, *args, **options) if evaluate and isinstance(result, cls) and result.args: pr2 = min(cls._should_evalf(a) for a in result.args) if pr2 > 0: pr = max(cls._should_evalf(a) for a in result.args) result = result.evalf(mlib.libmpf.prec_to_dps(pr)) return result @classmethod def _should_evalf(cls, arg): """ Decide if the function should automatically evalf(). By default (in this implementation), this happens if (and only if) the ARG is a floating point number. This function is used by __new__. Returns the precision to evalf to, or -1 if it shouldn't evalf. """ from sympy.core.evalf import pure_complex if arg.is_Float: return arg._prec if not arg.is_Add: return -1 m = pure_complex(arg) if m is None or not (m[0].is_Float or m[1].is_Float): return -1 l = [i._prec for i in m if i.is_Float] l.append(-1) return max(l) @classmethod def class_key(cls): from sympy.sets.fancysets import Naturals0 funcs = { 'exp': 10, 'log': 11, 'sin': 20, 'cos': 21, 'tan': 22, 'cot': 23, 'sinh': 30, 'cosh': 31, 'tanh': 32, 'coth': 33, 'conjugate': 40, 're': 41, 'im': 42, 'arg': 43, } name = cls.__name__ try: i = funcs[name] except KeyError: i = 0 if isinstance(cls.nargs, Naturals0) else 10000 return 4, i, name @property def is_commutative(self): """ Returns whether the function is commutative. """ if all(getattr(t, 'is_commutative') for t in self.args): return True else: return False def _eval_evalf(self, prec): # Lookup mpmath function based on name try: if isinstance(self, AppliedUndef): # Shouldn't lookup in mpmath but might have ._imp_ raise AttributeError fname = self.func.__name__ if not hasattr(mpmath, fname): from sympy.utilities.lambdify import MPMATH_TRANSLATIONS fname = MPMATH_TRANSLATIONS[fname] func = getattr(mpmath, fname) except (AttributeError, KeyError): try: return Float(self._imp_(*[i.evalf(prec) for i in self.args]), prec) except (AttributeError, TypeError, ValueError): return # Convert all args to mpf or mpc # Convert the arguments to *higher* precision than requested for the # final result. # XXX + 5 is a guess, it is similar to what is used in evalf.py. Should # we be more intelligent about it? try: args = [arg._to_mpmath(prec + 5) for arg in self.args] def bad(m): from mpmath import mpf, mpc # the precision of an mpf value is the last element # if that is 1 (and m[1] is not 1 which would indicate a # power of 2), then the eval failed; so check that none of # the arguments failed to compute to a finite precision. # Note: An mpc value has two parts, the re and imag tuple; # check each of those parts, too. Anything else is allowed to # pass if isinstance(m, mpf): m = m._mpf_ return m[1] !=1 and m[-1] == 1 elif isinstance(m, mpc): m, n = m._mpc_ return m[1] !=1 and m[-1] == 1 and \ n[1] !=1 and n[-1] == 1 else: return False if any(bad(a) for a in args): raise ValueError # one or more args failed to compute with significance except ValueError: return with mpmath.workprec(prec): v = func(*args) return Expr._from_mpmath(v, prec) def _eval_derivative(self, s): # f(x).diff(s) -> x.diff(s) * f.fdiff(1)(s) i = 0 l = [] for a in self.args: i += 1 da = a.diff(s) if da is S.Zero: continue try: df = self.fdiff(i) except ArgumentIndexError: df = Function.fdiff(self, i) l.append(df * da) return Add(*l) def _eval_is_commutative(self): return fuzzy_and(a.is_commutative for a in self.args) def _eval_is_complex(self): return fuzzy_and(a.is_complex for a in self.args) def as_base_exp(self): """ Returns the method as the 2-tuple (base, exponent). """ return self, S.One def _eval_aseries(self, n, args0, x, logx): """ Compute an asymptotic expansion around args0, in terms of self.args. This function is only used internally by _eval_nseries and should not be called directly; derived classes can overwrite this to implement asymptotic expansions. """ from sympy.utilities.misc import filldedent raise PoleError(filldedent(''' Asymptotic expansion of %s around %s is not implemented.''' % (type(self), args0))) def _eval_nseries(self, x, n, logx): """ This function does compute series for multivariate functions, but the expansion is always in terms of *one* variable. Examples ======== >>> from sympy import atan2 >>> from sympy.abc import x, y >>> atan2(x, y).series(x, n=2) atan2(0, y) + x/y + O(x**2) >>> atan2(x, y).series(y, n=2) -y/x + atan2(x, 0) + O(y**2) This function also computes asymptotic expansions, if necessary and possible: >>> from sympy import loggamma >>> loggamma(1/x)._eval_nseries(x,0,None) -1/x - log(x)/x + log(x)/2 + O(1) """ from sympy import Order from sympy.sets.sets import FiniteSet args = self.args args0 = [t.limit(x, 0) for t in args] if any(t.is_finite is False for t in args0): from sympy import oo, zoo, nan # XXX could use t.as_leading_term(x) here but it's a little # slower a = [t.compute_leading_term(x, logx=logx) for t in args] a0 = [t.limit(x, 0) for t in a] if any([t.has(oo, -oo, zoo, nan) for t in a0]): return self._eval_aseries(n, args0, x, logx) # Careful: the argument goes to oo, but only logarithmically so. We # are supposed to do a power series expansion "around the # logarithmic term". e.g. # f(1+x+log(x)) # -> f(1+logx) + x*f'(1+logx) + O(x**2) # where 'logx' is given in the argument a = [t._eval_nseries(x, n, logx) for t in args] z = [r - r0 for (r, r0) in zip(a, a0)] p = [Dummy() for t in z] q = [] v = None for ai, zi, pi in zip(a0, z, p): if zi.has(x): if v is not None: raise NotImplementedError q.append(ai + pi) v = pi else: q.append(ai) e1 = self.func(*q) if v is None: return e1 s = e1._eval_nseries(v, n, logx) o = s.getO() s = s.removeO() s = s.subs(v, zi).expand() + Order(o.expr.subs(v, zi), x) return s if (self.func.nargs is S.Naturals0 or (self.func.nargs == FiniteSet(1) and args0[0]) or any(c > 1 for c in self.func.nargs)): e = self e1 = e.expand() if e == e1: #for example when e = sin(x+1) or e = sin(cos(x)) #let's try the general algorithm term = e.subs(x, S.Zero) if term.is_finite is False or term is S.NaN: raise PoleError("Cannot expand %s around 0" % (self)) series = term fact = S.One _x = Dummy('x') e = e.subs(x, _x) for i in range(n - 1): i += 1 fact *= Rational(i) e = e.diff(_x) subs = e.subs(_x, S.Zero) if subs is S.NaN: # try to evaluate a limit if we have to subs = e.limit(_x, S.Zero) if subs.is_finite is False: raise PoleError("Cannot expand %s around 0" % (self)) term = subs*(x**i)/fact term = term.expand() series += term return series + Order(x**n, x) return e1.nseries(x, n=n, logx=logx) arg = self.args[0] l = [] g = None # try to predict a number of terms needed nterms = n + 2 cf = Order(arg.as_leading_term(x), x).getn() if cf != 0: nterms = int(nterms / cf) for i in range(nterms): g = self.taylor_term(i, arg, g) g = g.nseries(x, n=n, logx=logx) l.append(g) return Add(*l) + Order(x**n, x) def fdiff(self, argindex=1): """ Returns the first derivative of the function. """ if not (1 <= argindex <= len(self.args)): raise ArgumentIndexError(self, argindex) ix = argindex - 1 A = self.args[ix] if A._diff_wrt: if len(self.args) == 1: return Derivative(self, A) if A.is_Symbol: for i, v in enumerate(self.args): if i != ix and A in v.free_symbols: # it can't be in any other argument's free symbols # issue 8510 break else: return Derivative(self, A) else: free = A.free_symbols for i, a in enumerate(self.args): if ix != i and a.free_symbols & free: break else: # there is no possible interaction bewtween args return Derivative(self, A) # See issue 4624 and issue 4719, 5600 and 8510 D = Dummy('xi_%i' % argindex, dummy_index=hash(A)) args = self.args[:ix] + (D,) + self.args[ix + 1:] return Subs(Derivative(self.func(*args), D), D, A) def _eval_as_leading_term(self, x): """Stub that should be overridden by new Functions to return the first non-zero term in a series if ever an x-dependent argument whose leading term vanishes as x -> 0 might be encountered. See, for example, cos._eval_as_leading_term. """ from sympy import Order args = [a.as_leading_term(x) for a in self.args] o = Order(1, x) if any(x in a.free_symbols and o.contains(a) for a in args): # Whereas x and any finite number are contained in O(1, x), # expressions like 1/x are not. If any arg simplified to a # vanishing expression as x -> 0 (like x or x**2, but not # 3, 1/x, etc...) then the _eval_as_leading_term is needed # to supply the first non-zero term of the series, # # e.g. expression leading term # ---------- ------------ # cos(1/x) cos(1/x) # cos(cos(x)) cos(1) # cos(x) 1 <- _eval_as_leading_term needed # sin(x) x <- _eval_as_leading_term needed # raise NotImplementedError( '%s has no _eval_as_leading_term routine' % self.func) else: return self.func(*args) def _sage_(self): import sage.all as sage fname = self.func.__name__ func = getattr(sage, fname,None) args = [arg._sage_() for arg in self.args] # In the case the function is not known in sage: if func is None: import sympy if getattr(sympy, fname,None) is None: # abstract function return sage.function(fname)(*args) else: # the function defined in sympy is not known in sage # this exception is caught in sage raise AttributeError return func(*args) class AppliedUndef(Function): """ Base class for expressions resulting from the application of an undefined function. """ is_number = False def __new__(cls, *args, **options): args = list(map(sympify, args)) obj = super(AppliedUndef, cls).__new__(cls, *args, **options) return obj def _eval_as_leading_term(self, x): return self def _sage_(self): import sage.all as sage fname = str(self.func) args = [arg._sage_() for arg in self.args] func = sage.function(fname)(*args) return func @property def _diff_wrt(self): """ Allow derivatives wrt to undefined functions. Examples ======== >>> from sympy import Function, Symbol >>> f = Function('f') >>> x = Symbol('x') >>> f(x)._diff_wrt True >>> f(x).diff(x) Derivative(f(x), x) """ return True class UndefinedFunction(FunctionClass): """ The (meta)class of undefined functions. """ def __new__(mcl, name, bases=(AppliedUndef,), __dict__=None, **kwargs): __dict__ = __dict__ or {} # Allow Function('f', real=True) __dict__.update({'is_' + arg: val for arg, val in kwargs.items() if arg in _assume_defined}) # You can add other attributes, although they do have to be hashable # (but seriously, if you want to add anything other than assumptions, # just subclass Function) __dict__.update(kwargs) # Save these for __eq__ __dict__.update({'_extra_kwargs': kwargs}) __dict__['__module__'] = None # For pickling ret = super(UndefinedFunction, mcl).__new__(mcl, name, bases, __dict__) ret.name = name return ret def __instancecheck__(cls, instance): return cls in type(instance).__mro__ _extra_kwargs = {} def __hash__(self): return hash((self.class_key(), frozenset(self._extra_kwargs.items()))) def __eq__(self, other): return (isinstance(other, self.__class__) and self.class_key() == other.class_key() and self._extra_kwargs == other._extra_kwargs) def __ne__(self, other): return not self == other class WildFunction(Function, AtomicExpr): """ A WildFunction function matches any function (with its arguments). Examples ======== >>> from sympy import WildFunction, Function, cos >>> from sympy.abc import x, y >>> F = WildFunction('F') >>> f = Function('f') >>> F.nargs Naturals0 >>> x.match(F) >>> F.match(F) {F_: F_} >>> f(x).match(F) {F_: f(x)} >>> cos(x).match(F) {F_: cos(x)} >>> f(x, y).match(F) {F_: f(x, y)} To match functions with a given number of arguments, set ``nargs`` to the desired value at instantiation: >>> F = WildFunction('F', nargs=2) >>> F.nargs {2} >>> f(x).match(F) >>> f(x, y).match(F) {F_: f(x, y)} To match functions with a range of arguments, set ``nargs`` to a tuple containing the desired number of arguments, e.g. if ``nargs = (1, 2)`` then functions with 1 or 2 arguments will be matched. >>> F = WildFunction('F', nargs=(1, 2)) >>> F.nargs {1, 2} >>> f(x).match(F) {F_: f(x)} >>> f(x, y).match(F) {F_: f(x, y)} >>> f(x, y, 1).match(F) """ include = set() def __init__(cls, name, **assumptions): from sympy.sets.sets import Set, FiniteSet cls.name = name nargs = assumptions.pop('nargs', S.Naturals0) if not isinstance(nargs, Set): # Canonicalize nargs here. See also FunctionClass. if is_sequence(nargs): nargs = tuple(ordered(set(nargs))) elif nargs is not None: nargs = (as_int(nargs),) nargs = FiniteSet(*nargs) cls.nargs = nargs def matches(self, expr, repl_dict={}, old=False): if not isinstance(expr, (AppliedUndef, Function)): return None if len(expr.args) not in self.nargs: return None repl_dict = repl_dict.copy() repl_dict[self] = expr return repl_dict class Derivative(Expr): """ Carries out differentiation of the given expression with respect to symbols. Examples ======== >>> from sympy import Derivative, Function, symbols, Subs >>> from sympy.abc import x, y >>> f, g = symbols('f g', cls=Function) >>> Derivative(x**2, x, evaluate=True) 2*x Denesting of derivatives retains the ordering of variables: >>> Derivative(Derivative(f(x, y), y), x) Derivative(f(x, y), y, x) Contiguously identical symbols are merged into a tuple giving the symbol and the count: >>> Derivative(f(x), x, x, y, x) Derivative(f(x), (x, 2), y, x) If the derivative cannot be performed, and evaluate is True, the order of the variables of differentiation will be made canonical: >>> Derivative(f(x, y), y, x, evaluate=True) Derivative(f(x, y), x, y) Derivatives with respect to undefined functions can be calculated: >>> Derivative(f(x)**2, f(x), evaluate=True) 2*f(x) Such derivatives will show up when the chain rule is used to evalulate a derivative: >>> f(g(x)).diff(x) Derivative(f(g(x)), g(x))*Derivative(g(x), x) Substitution is used to represent derivatives of functions with arguments that are not symbols or functions: >>> f(2*x + 3).diff(x) == 2*Subs(f(y).diff(y), y, 2*x + 3) True Notes ===== Simplification of high-order derivatives: Because there can be a significant amount of simplification that can be done when multiple differentiations are performed, results will be automatically simplified in a fairly conservative fashion unless the keyword ``simplify`` is set to False. >>> from sympy import cos, sin, sqrt, diff, Function, symbols >>> from sympy.abc import x, y, z >>> f, g = symbols('f,g', cls=Function) >>> e = sqrt((x + 1)**2 + x) >>> diff(e, (x, 5), simplify=False).count_ops() 136 >>> diff(e, (x, 5)).count_ops() 30 Ordering of variables: If evaluate is set to True and the expression cannot be evaluated, the list of differentiation symbols will be sorted, that is, the expression is assumed to have continuous derivatives up to the order asked. Derivative wrt non-Symbols: For the most part, one may not differentiate wrt non-symbols. For example, we do not allow differentiation wrt `x*y` because there are multiple ways of structurally defining where x*y appears in an expression: a very strict definition would make (x*y*z).diff(x*y) == 0. Derivatives wrt defined functions (like cos(x)) are not allowed, either: >>> (x*y*z).diff(x*y) Traceback (most recent call last): ... ValueError: Can't calculate derivative wrt x*y. To make it easier to work with variational calculus, however, derivatives wrt AppliedUndef and Derivatives are allowed. For example, in the Euler-Lagrange method one may write F(t, u, v) where u = f(t) and v = f'(t). These variables can be written explicity as functions of time:: >>> from sympy.abc import t >>> F = Function('F') >>> U = f(t) >>> V = U.diff(t) The derivative wrt f(t) can be obtained directly: >>> direct = F(t, U, V).diff(U) When differentiation wrt a non-Symbol is attempted, the non-Symbol is temporarily converted to a Symbol while the differentiation is performed and the same answer is obtained: >>> indirect = F(t, U, V).subs(U, x).diff(x).subs(x, U) >>> assert direct == indirect The implication of this non-symbol replacement is that all functions are treated as independent of other functions and the symbols are independent of the functions that contain them:: >>> x.diff(f(x)) 0 >>> g(x).diff(f(x)) 0 It also means that derivatives are assumed to depend only on the variables of differentiation, not on anything contained within the expression being differentiated:: >>> F = f(x) >>> Fx = F.diff(x) >>> Fx.diff(F) # derivative depends on x, not F 0 >>> Fxx = Fx.diff(x) >>> Fxx.diff(Fx) # derivative depends on x, not Fx 0 The last example can be made explicit by showing the replacement of Fx in Fxx with y: >>> Fxx.subs(Fx, y) Derivative(y, x) Since that in itself will evaluate to zero, differentiating wrt Fx will also be zero: >>> _.doit() 0 Replacing undefined functions with concrete expressions One must be careful to replace undefined functions with expressions that contain variables consistent with the function definition and the variables of differentiation or else insconsistent result will be obtained. Consider the following example: >>> eq = f(x)*g(y) >>> eq.subs(f(x), x*y).diff(x, y).doit() y*Derivative(g(y), y) + g(y) >>> eq.diff(x, y).subs(f(x), x*y).doit() y*Derivative(g(y), y) The results differ because `f(x)` was replaced with an expression that involved both variables of differentiation. In the abstract case, differentiation of `f(x)` by `y` is 0; in the concrete case, the presence of `y` made that derivative nonvanishing and produced the extra `g(y)` term. Defining differentiation for an object An object must define ._eval_derivative(symbol) method that returns the differentiation result. This function only needs to consider the non-trivial case where expr contains symbol and it should call the diff() method internally (not _eval_derivative); Derivative should be the only one to call _eval_derivative. Any class can allow derivatives to be taken with respect to itself (while indicating its scalar nature). See the docstring of Expr._diff_wrt. See Also ======== _sort_variable_count """ is_Derivative = True @property def _diff_wrt(self): """An expression may be differentiated wrt a Derivative if it is in elementary form. Examples ======== >>> from sympy import Function, Derivative, cos >>> from sympy.abc import x >>> f = Function('f') >>> Derivative(f(x), x)._diff_wrt True >>> Derivative(cos(x), x)._diff_wrt False >>> Derivative(x + 1, x)._diff_wrt False A Derivative might be an unevaluated form of what will not be a valid variable of differentiation if evaluated. For example, >>> Derivative(f(f(x)), x).doit() Derivative(f(x), x)*Derivative(f(f(x)), f(x)) Such an expression will present the same ambiguities as arise when dealing with any other product, like `2*x`, so `_diff_wrt` is False: >>> Derivative(f(f(x)), x)._diff_wrt False """ return self.expr._diff_wrt and isinstance(self.doit(), Derivative) def __new__(cls, expr, *variables, **kwargs): from sympy.matrices.common import MatrixCommon from sympy import Integer from sympy.tensor.array import Array, NDimArray from sympy.utilities.misc import filldedent expr = sympify(expr) try: has_symbol_set = isinstance(expr.free_symbols, set) except AttributeError: has_symbol_set = False if not has_symbol_set: raise ValueError(filldedent(''' Since there are no variables in the expression %s, it cannot be differentiated.''' % expr)) # determine value for variables if it wasn't given if not variables: variables = expr.free_symbols if len(variables) != 1: if expr.is_number: return S.Zero if len(variables) == 0: raise ValueError(filldedent(''' Since there are no variables in the expression, the variable(s) of differentiation must be supplied to differentiate %s''' % expr)) else: raise ValueError(filldedent(''' Since there is more than one variable in the expression, the variable(s) of differentiation must be supplied to differentiate %s''' % expr)) # Standardize the variables by sympifying them: variables = list(sympify(variables)) # Split the list of variables into a list of the variables we are diff # wrt, where each element of the list has the form (s, count) where # s is the entity to diff wrt and count is the order of the # derivative. variable_count = [] array_likes = (tuple, list, Tuple) for i, v in enumerate(variables): if isinstance(v, Integer): if i == 0: raise ValueError("First variable cannot be a number: %i" % v) count = v prev, prevcount = variable_count[-1] if prevcount != 1: raise TypeError("tuple {0} followed by number {1}".format((prev, prevcount), v)) if count == 0: variable_count.pop() else: variable_count[-1] = Tuple(prev, count) else: if isinstance(v, array_likes): if len(v) == 0: # Ignore empty tuples: Derivative(expr, ... , (), ... ) continue if isinstance(v[0], array_likes): # Derive by array: Derivative(expr, ... , [[x, y, z]], ... ) if len(v) == 1: v = Array(v[0]) count = 1 else: v, count = v v = Array(v) else: v, count = v if count == 0: continue else: count = 1 variable_count.append(Tuple(v, count)) # light evaluation of contiguous, identical # items: (x, 1), (x, 1) -> (x, 2) merged = [] for t in variable_count: v, c = t if c.is_negative: raise ValueError( 'order of differentiation must be nonnegative') if merged and merged[-1][0] == v: c += merged[-1][1] if not c: merged.pop() else: merged[-1] = Tuple(v, c) else: merged.append(t) variable_count = merged # sanity check of variables of differentation; we waited # until the counts were computed since some variables may # have been removed because the count was 0 for v, c in variable_count: # v must have _diff_wrt True if not v._diff_wrt: __ = '' # filler to make error message neater raise ValueError(filldedent(''' Can't calculate derivative wrt %s.%s''' % (v, __))) # We make a special case for 0th derivative, because there is no # good way to unambiguously print this. if len(variable_count) == 0: return expr evaluate = kwargs.get('evaluate', False) if evaluate: if isinstance(expr, Derivative): expr = expr.canonical variable_count = [ (v.canonical if isinstance(v, Derivative) else v, c) for v, c in variable_count] # Look for a quick exit if there are symbols that don't appear in # expression at all. Note, this cannot check non-symbols like # Derivatives as those can be created by intermediate # derivatives. zero = False free = expr.free_symbols for v, c in variable_count: vfree = v.free_symbols if c.is_positive and vfree: if isinstance(v, AppliedUndef): # these match exactly since # x.diff(f(x)) == g(x).diff(f(x)) == 0 # and are not created by differentiation D = Dummy() if not expr.xreplace({v: D}).has(D): zero = True break elif isinstance(v, Symbol) and v not in free: zero = True break else: if not free & vfree: # e.g. v is IndexedBase or Matrix zero = True break if zero: if isinstance(expr, (MatrixCommon, NDimArray)): return expr.zeros(*expr.shape) else: return S.Zero # make the order of symbols canonical #TODO: check if assumption of discontinuous derivatives exist variable_count = cls._sort_variable_count(variable_count) # denest if isinstance(expr, Derivative): variable_count = list(expr.variable_count) + variable_count expr = expr.expr return Derivative(expr, *variable_count, **kwargs) # we return here if evaluate is False or if there is no # _eval_derivative method if not evaluate or not hasattr(expr, '_eval_derivative'): # return an unevaluated Derivative if evaluate and variable_count == [(expr, 1)] and expr.is_scalar: # special hack providing evaluation for classes # that have defined is_scalar=True but have no # _eval_derivative defined return S.One return Expr.__new__(cls, expr, *variable_count) # evaluate the derivative by calling _eval_derivative method # of expr for each variable # ------------------------------------------------------------- nderivs = 0 # how many derivatives were performed unhandled = [] for i, (v, count) in enumerate(variable_count): old_expr = expr old_v = None is_symbol = v.is_symbol or isinstance(v, (Iterable, Tuple, MatrixCommon, NDimArray)) if not is_symbol: old_v = v v = Dummy('xi') expr = expr.xreplace({old_v: v}) # Derivatives and UndefinedFunctions are independent # of all others clashing = not (isinstance(old_v, Derivative) or \ isinstance(old_v, AppliedUndef)) if not v in expr.free_symbols and not clashing: return expr.diff(v) # expr's version of 0 if not old_v.is_scalar and not hasattr( old_v, '_eval_derivative'): # special hack providing evaluation for classes # that have defined is_scalar=True but have no # _eval_derivative defined expr *= old_v.diff(old_v) # Evaluate the derivative `n` times. If # `_eval_derivative_n_times` is not overridden by the current # object, the default in `Basic` will call a loop over # `_eval_derivative`: obj = expr._eval_derivative_n_times(v, count) if obj is not None and obj.is_zero: return obj nderivs += count if old_v is not None: if obj is not None: # remove the dummy that was used obj = obj.subs(v, old_v) # restore expr and v expr = old_expr v = old_v if obj is None: # we've already checked for quick-exit conditions # that give 0 so the remaining variables # are contained in the expression but the expression # did not compute a derivative so we stop taking # derivatives unhandled = variable_count[i:] break expr = obj # what we have so far can be made canonical expr = expr.replace( lambda x: isinstance(x, Derivative), lambda x: x.canonical) if unhandled: if isinstance(expr, Derivative): unhandled = list(expr.variable_count) + unhandled expr = expr.expr expr = Expr.__new__(cls, expr, *unhandled) if (nderivs > 1) == True and kwargs.get('simplify', True): from sympy.core.exprtools import factor_terms from sympy.simplify.simplify import signsimp expr = factor_terms(signsimp(expr)) return expr @property def canonical(cls): return cls.func(cls.expr, *Derivative._sort_variable_count(cls.variable_count)) @classmethod def _sort_variable_count(cls, vc): """ Sort (variable, count) pairs into canonical order while retaining order of variables that do not commute during differentiation: * symbols and functions commute with each other * derivatives commute with each other * a derivative doesn't commute with anything it contains * any other object is not allowed to commute if it has free symbols in common with another object Examples ======== >>> from sympy import Derivative, Function, symbols, cos >>> vsort = Derivative._sort_variable_count >>> x, y, z = symbols('x y z') >>> f, g, h = symbols('f g h', cls=Function) Contiguous items are collapsed into one pair: >>> vsort([(x, 1), (x, 1)]) [(x, 2)] >>> vsort([(y, 1), (f(x), 1), (y, 1), (f(x), 1)]) [(y, 2), (f(x), 2)] Ordering is canonical. >>> def vsort0(*v): ... # docstring helper to ... # change vi -> (vi, 0), sort, and return vi vals ... return [i[0] for i in vsort([(i, 0) for i in v])] >>> vsort0(y, x) [x, y] >>> vsort0(g(y), g(x), f(y)) [f(y), g(x), g(y)] Symbols are sorted as far to the left as possible but never move to the left of a derivative having the same symbol in its variables; the same applies to AppliedUndef which are always sorted after Symbols: >>> dfx = f(x).diff(x) >>> assert vsort0(dfx, y) == [y, dfx] >>> assert vsort0(dfx, x) == [dfx, x] """ from sympy.utilities.iterables import uniq, topological_sort if not vc: return [] vc = list(vc) if len(vc) == 1: return [Tuple(*vc[0])] V = list(range(len(vc))) E = [] v = lambda i: vc[i][0] D = Dummy() def _block(d, v, wrt=False): # return True if v should not come before d else False if d == v: return wrt if d.is_Symbol: return False if isinstance(d, Derivative): # a derivative blocks if any of it's variables contain # v; the wrt flag will return True for an exact match # and will cause an AppliedUndef to block if v is in # the arguments if any(_block(k, v, wrt=True) for k in d._wrt_variables): return True return False if not wrt and isinstance(d, AppliedUndef): return False if v.is_Symbol: return v in d.free_symbols if isinstance(v, AppliedUndef): return _block(d.xreplace({v: D}), D) return d.free_symbols & v.free_symbols for i in range(len(vc)): for j in range(i): if _block(v(j), v(i)): E.append((j,i)) # this is the default ordering to use in case of ties O = dict(zip(ordered(uniq([i for i, c in vc])), range(len(vc)))) ix = topological_sort((V, E), key=lambda i: O[v(i)]) # merge counts of contiguously identical items merged = [] for v, c in [vc[i] for i in ix]: if merged and merged[-1][0] == v: merged[-1][1] += c else: merged.append([v, c]) return [Tuple(*i) for i in merged] def _eval_is_commutative(self): return self.expr.is_commutative def _eval_derivative(self, v): # If v (the variable of differentiation) is not in # self.variables, we might be able to take the derivative. if v not in self._wrt_variables: dedv = self.expr.diff(v) if isinstance(dedv, Derivative): return dedv.func(dedv.expr, *(self.variable_count + dedv.variable_count)) # dedv (d(self.expr)/dv) could have simplified things such that the # derivative wrt things in self.variables can now be done. Thus, # we set evaluate=True to see if there are any other derivatives # that can be done. The most common case is when dedv is a simple # number so that the derivative wrt anything else will vanish. return self.func(dedv, *self.variables, evaluate=True) # In this case v was in self.variables so the derivative wrt v has # already been attempted and was not computed, either because it # couldn't be or evaluate=False originally. variable_count = list(self.variable_count) variable_count.append((v, 1)) return self.func(self.expr, *variable_count, evaluate=False) def doit(self, **hints): expr = self.expr if hints.get('deep', True): expr = expr.doit(**hints) hints['evaluate'] = True return self.func(expr, *self.variable_count, **hints) @_sympifyit('z0', NotImplementedError) def doit_numerically(self, z0): """ Evaluate the derivative at z numerically. When we can represent derivatives at a point, this should be folded into the normal evalf. For now, we need a special method. """ import mpmath from sympy.core.expr import Expr if len(self.free_symbols) != 1 or len(self.variables) != 1: raise NotImplementedError('partials and higher order derivatives') z = list(self.free_symbols)[0] def eval(x): f0 = self.expr.subs(z, Expr._from_mpmath(x, prec=mpmath.mp.prec)) f0 = f0.evalf(mlib.libmpf.prec_to_dps(mpmath.mp.prec)) return f0._to_mpmath(mpmath.mp.prec) return Expr._from_mpmath(mpmath.diff(eval, z0._to_mpmath(mpmath.mp.prec)), mpmath.mp.prec) @property def expr(self): return self._args[0] @property def _wrt_variables(self): # return the variables of differentiation without # respect to the type of count (int or symbolic) return [i[0] for i in self.variable_count] @property def variables(self): # TODO: deprecate? YES, make this 'enumerated_variables' and # name _wrt_variables as variables # TODO: support for `d^n`? rv = [] for v, count in self.variable_count: if not count.is_Integer: raise TypeError(filldedent(''' Cannot give expansion for symbolic count. If you just want a list of all variables of differentiation, use _wrt_variables.''')) rv.extend([v]*count) return tuple(rv) @property def variable_count(self): return self._args[1:] @property def derivative_count(self): return sum([count for var, count in self.variable_count], 0) @property def free_symbols(self): return self.expr.free_symbols def _eval_subs(self, old, new): # The substitution (old, new) cannot be done inside # Derivative(expr, vars) for a variety of reasons # as handled below. if old in self._wrt_variables: # quick exit case if not getattr(new, '_diff_wrt', False): # case (0): new is not a valid variable of # differentiation if isinstance(old, Symbol): # don't introduce a new symbol if the old will do return Subs(self, old, new) else: xi = Dummy('xi') return Subs(self.xreplace({old: xi}), xi, new) # If both are Derivatives with the same expr, check if old is # equivalent to self or if old is a subderivative of self. if old.is_Derivative and old.expr == self.expr: if self.canonical == old.canonical: return new # collections.Counter doesn't have __le__ def _subset(a, b): return all((a[i] <= b[i]) == True for i in a) old_vars = Counter(dict(reversed(old.variable_count))) self_vars = Counter(dict(reversed(self.variable_count))) if _subset(old_vars, self_vars): return Derivative(new, *(self_vars - old_vars).items()).canonical args = list(self.args) newargs = list(x._subs(old, new) for x in args) if args[0] == old: # complete replacement of self.expr # we already checked that the new is valid so we know # it won't be a problem should it appear in variables return Derivative(*newargs) if newargs[0] != args[0]: # case (1) can't change expr by introducing something that is in # the _wrt_variables if it was already in the expr # e.g. # for Derivative(f(x, g(y)), y), x cannot be replaced with # anything that has y in it; for f(g(x), g(y)).diff(g(y)) # g(x) cannot be replaced with anything that has g(y) syms = {vi: Dummy() for vi in self._wrt_variables if not vi.is_Symbol} wrt = set(syms.get(vi, vi) for vi in self._wrt_variables) forbidden = args[0].xreplace(syms).free_symbols & wrt nfree = new.xreplace(syms).free_symbols ofree = old.xreplace(syms).free_symbols if (nfree - ofree) & forbidden: return Subs(self, old, new) viter = ((i, j) for ((i,_), (j,_)) in zip(newargs[1:], args[1:])) if any(i != j for i, j in viter): # a wrt-variable change # case (2) can't change vars by introducing a variable # that is contained in expr, e.g. # for Derivative(f(z, g(h(x), y)), y), y cannot be changed to # x, h(x), or g(h(x), y) for a in _atomic(self.expr, recursive=True): for i in range(1, len(newargs)): vi, _ = newargs[i] if a == vi and vi != args[i][0]: return Subs(self, old, new) # more arg-wise checks vc = newargs[1:] oldv = self._wrt_variables newe = self.expr subs = [] for i, (vi, ci) in enumerate(vc): if not vi._diff_wrt: # case (3) invalid differentiation expression so # create a replacement dummy xi = Dummy('xi_%i' % i) # replace the old valid variable with the dummy # in the expression newe = newe.xreplace({oldv[i]: xi}) # and replace the bad variable with the dummy vc[i] = (xi, ci) # and record the dummy with the new (invalid) # differentiation expression subs.append((xi, vi)) if subs: # handle any residual substitution in the expression newe = newe._subs(old, new) # return the Subs-wrapped derivative return Subs(Derivative(newe, *vc), *zip(*subs)) # everything was ok return Derivative(*newargs) def _eval_lseries(self, x, logx): dx = self.variables for term in self.expr.lseries(x, logx=logx): yield self.func(term, *dx) def _eval_nseries(self, x, n, logx): arg = self.expr.nseries(x, n=n, logx=logx) o = arg.getO() dx = self.variables rv = [self.func(a, *dx) for a in Add.make_args(arg.removeO())] if o: rv.append(o/x) return Add(*rv) def _eval_as_leading_term(self, x): series_gen = self.expr.lseries(x) d = S.Zero for leading_term in series_gen: d = diff(leading_term, *self.variables) if d != 0: break return d def _sage_(self): import sage.all as sage args = [arg._sage_() for arg in self.args] return sage.derivative(*args) def as_finite_difference(self, points=1, x0=None, wrt=None): """ Expresses a Derivative instance as a finite difference. Parameters ========== points : sequence or coefficient, optional If sequence: discrete values (length >= order+1) of the independent variable used for generating the finite difference weights. If it is a coefficient, it will be used as the step-size for generating an equidistant sequence of length order+1 centered around ``x0``. Default: 1 (step-size 1) x0 : number or Symbol, optional the value of the independent variable (``wrt``) at which the derivative is to be approximated. Default: same as ``wrt``. wrt : Symbol, optional "with respect to" the variable for which the (partial) derivative is to be approximated for. If not provided it is required that the derivative is ordinary. Default: ``None``. Examples ======== >>> from sympy import symbols, Function, exp, sqrt, Symbol >>> x, h = symbols('x h') >>> f = Function('f') >>> f(x).diff(x).as_finite_difference() -f(x - 1/2) + f(x + 1/2) The default step size and number of points are 1 and ``order + 1`` respectively. We can change the step size by passing a symbol as a parameter: >>> f(x).diff(x).as_finite_difference(h) -f(-h/2 + x)/h + f(h/2 + x)/h We can also specify the discretized values to be used in a sequence: >>> f(x).diff(x).as_finite_difference([x, x+h, x+2*h]) -3*f(x)/(2*h) + 2*f(h + x)/h - f(2*h + x)/(2*h) The algorithm is not restricted to use equidistant spacing, nor do we need to make the approximation around ``x0``, but we can get an expression estimating the derivative at an offset: >>> e, sq2 = exp(1), sqrt(2) >>> xl = [x-h, x+h, x+e*h] >>> f(x).diff(x, 1).as_finite_difference(xl, x+h*sq2) # doctest: +ELLIPSIS 2*h*((h + sqrt(2)*h)/(2*h) - (-sqrt(2)*h + h)/(2*h))*f(E*h + x)/... Partial derivatives are also supported: >>> y = Symbol('y') >>> d2fdxdy=f(x,y).diff(x,y) >>> d2fdxdy.as_finite_difference(wrt=x) -Derivative(f(x - 1/2, y), y) + Derivative(f(x + 1/2, y), y) We can apply ``as_finite_difference`` to ``Derivative`` instances in compound expressions using ``replace``: >>> (1 + 42**f(x).diff(x)).replace(lambda arg: arg.is_Derivative, ... lambda arg: arg.as_finite_difference()) 42**(-f(x - 1/2) + f(x + 1/2)) + 1 See also ======== sympy.calculus.finite_diff.apply_finite_diff sympy.calculus.finite_diff.differentiate_finite sympy.calculus.finite_diff.finite_diff_weights """ from ..calculus.finite_diff import _as_finite_diff return _as_finite_diff(self, points, x0, wrt) class Lambda(Expr): """ Lambda(x, expr) represents a lambda function similar to Python's 'lambda x: expr'. A function of several variables is written as Lambda((x, y, ...), expr). A simple example: >>> from sympy import Lambda >>> from sympy.abc import x >>> f = Lambda(x, x**2) >>> f(4) 16 For multivariate functions, use: >>> from sympy.abc import y, z, t >>> f2 = Lambda((x, y, z, t), x + y**z + t**z) >>> f2(1, 2, 3, 4) 73 A handy shortcut for lots of arguments: >>> p = x, y, z >>> f = Lambda(p, x + y*z) >>> f(*p) x + y*z """ is_Function = True def __new__(cls, variables, expr): from sympy.sets.sets import FiniteSet v = list(variables) if iterable(variables) else [variables] for i in v: if not getattr(i, 'is_symbol', False): raise TypeError('variable is not a symbol: %s' % i) if len(v) == 1 and v[0] == expr: return S.IdentityFunction obj = Expr.__new__(cls, Tuple(*v), sympify(expr)) obj.nargs = FiniteSet(len(v)) return obj @property def variables(self): """The variables used in the internal representation of the function""" return self._args[0] bound_symbols = variables @property def expr(self): """The return value of the function""" return self._args[1] @property def free_symbols(self): return self.expr.free_symbols - set(self.variables) def __call__(self, *args): n = len(args) if n not in self.nargs: # Lambda only ever has 1 value in nargs # XXX: exception message must be in exactly this format to # make it work with NumPy's functions like vectorize(). See, # for example, https://github.com/numpy/numpy/issues/1697. # The ideal solution would be just to attach metadata to # the exception and change NumPy to take advantage of this. ## XXX does this apply to Lambda? If not, remove this comment. temp = ('%(name)s takes exactly %(args)s ' 'argument%(plural)s (%(given)s given)') raise TypeError(temp % { 'name': self, 'args': list(self.nargs)[0], 'plural': 's'*(list(self.nargs)[0] != 1), 'given': n}) return self.expr.xreplace(dict(list(zip(self.variables, args)))) def __eq__(self, other): if not isinstance(other, Lambda): return False if self.nargs != other.nargs: return False selfexpr = self.args[1] otherexpr = other.args[1] otherexpr = otherexpr.xreplace(dict(list(zip(other.args[0], self.args[0])))) return selfexpr == otherexpr def __ne__(self, other): return not(self == other) def __hash__(self): return super(Lambda, self).__hash__() def _hashable_content(self): return (self.expr.xreplace(self.canonical_variables),) @property def is_identity(self): """Return ``True`` if this ``Lambda`` is an identity function. """ if len(self.args) == 2: return self.args[0] == self.args[1] else: return None class Subs(Expr): """ Represents unevaluated substitutions of an expression. ``Subs(expr, x, x0)`` receives 3 arguments: an expression, a variable or list of distinct variables and a point or list of evaluation points corresponding to those variables. ``Subs`` objects are generally useful to represent unevaluated derivatives calculated at a point. The variables may be expressions, but they are subjected to the limitations of subs(), so it is usually a good practice to use only symbols for variables, since in that case there can be no ambiguity. There's no automatic expansion - use the method .doit() to effect all possible substitutions of the object and also of objects inside the expression. When evaluating derivatives at a point that is not a symbol, a Subs object is returned. One is also able to calculate derivatives of Subs objects - in this case the expression is always expanded (for the unevaluated form, use Derivative()). Examples ======== >>> from sympy import Subs, Function, sin, cos >>> from sympy.abc import x, y, z >>> f = Function('f') Subs are created when a particular substitution cannot be made. The x in the derivative cannot be replaced with 0 because 0 is not a valid variables of differentiation: >>> f(x).diff(x).subs(x, 0) Subs(Derivative(f(x), x), x, 0) Once f is known, the derivative and evaluation at 0 can be done: >>> _.subs(f, sin).doit() == sin(x).diff(x).subs(x, 0) == cos(0) True Subs can also be created directly with one or more variables: >>> Subs(f(x)*sin(y) + z, (x, y), (0, 1)) Subs(z + f(x)*sin(y), (x, y), (0, 1)) >>> _.doit() z + f(0)*sin(1) Notes ===== In order to allow expressions to combine before doit is done, a representation of the Subs expression is used internally to make expressions that are superficially different compare the same: >>> a, b = Subs(x, x, 0), Subs(y, y, 0) >>> a + b 2*Subs(x, x, 0) This can lead to unexpected consequences when using methods like `has` that are cached: >>> s = Subs(x, x, 0) >>> s.has(x), s.has(y) (True, False) >>> ss = s.subs(x, y) >>> ss.has(x), ss.has(y) (True, False) >>> s, ss (Subs(x, x, 0), Subs(y, y, 0)) """ def __new__(cls, expr, variables, point, **assumptions): from sympy import Symbol if not is_sequence(variables, Tuple): variables = [variables] variables = Tuple(*variables) if has_dups(variables): repeated = [str(v) for v, i in Counter(variables).items() if i > 1] __ = ', '.join(repeated) raise ValueError(filldedent(''' The following expressions appear more than once: %s ''' % __)) point = Tuple(*(point if is_sequence(point, Tuple) else [point])) if len(point) != len(variables): raise ValueError('Number of point values must be the same as ' 'the number of variables.') if not point: return sympify(expr) # denest if isinstance(expr, Subs): variables = expr.variables + variables point = expr.point + point expr = expr.expr else: expr = sympify(expr) # use symbols with names equal to the point value (with preppended _) # to give a variable-independent expression pre = "_" pts = sorted(set(point), key=default_sort_key) from sympy.printing import StrPrinter class CustomStrPrinter(StrPrinter): def _print_Dummy(self, expr): return str(expr) + str(expr.dummy_index) def mystr(expr, **settings): p = CustomStrPrinter(settings) return p.doprint(expr) while 1: s_pts = {p: Symbol(pre + mystr(p)) for p in pts} reps = [(v, s_pts[p]) for v, p in zip(variables, point)] # if any underscore-preppended symbol is already a free symbol # and is a variable with a different point value, then there # is a clash, e.g. _0 clashes in Subs(_0 + _1, (_0, _1), (1, 0)) # because the new symbol that would be created is _1 but _1 # is already mapped to 0 so __0 and __1 are used for the new # symbols if any(r in expr.free_symbols and r in variables and Symbol(pre + mystr(point[variables.index(r)])) != r for _, r in reps): pre += "_" continue break obj = Expr.__new__(cls, expr, Tuple(*variables), point) obj._expr = expr.xreplace(dict(reps)) return obj def _eval_is_commutative(self): return self.expr.is_commutative def doit(self, **hints): e, v, p = self.args # remove self mappings for i, (vi, pi) in enumerate(zip(v, p)): if vi == pi: v = v[:i] + v[i + 1:] p = p[:i] + p[i + 1:] if not v: return self.expr if isinstance(e, Derivative): # apply functions first, e.g. f -> cos undone = [] for i, vi in enumerate(v): if isinstance(vi, FunctionClass): e = e.subs(vi, p[i]) else: undone.append((vi, p[i])) if not isinstance(e, Derivative): e = e.doit() if isinstance(e, Derivative): # do Subs that aren't related to differentiation undone2 = [] D = Dummy() for vi, pi in undone: if D not in e.xreplace({vi: D}).free_symbols: e = e.subs(vi, pi) else: undone2.append((vi, pi)) undone = undone2 # differentiate wrt variables that are present wrt = [] D = Dummy() expr = e.expr free = expr.free_symbols for vi, ci in e.variable_count: if isinstance(vi, Symbol) and vi in free: expr = expr.diff((vi, ci)) elif D in expr.subs(vi, D).free_symbols: expr = expr.diff((vi, ci)) else: wrt.append((vi, ci)) # inject remaining subs rv = expr.subs(undone) # do remaining differentiation *in order given* for vc in wrt: rv = rv.diff(vc) else: # inject remaining subs rv = e.subs(undone) else: rv = e.doit(**hints).subs(list(zip(v, p))) if hints.get('deep', True) and rv != self: rv = rv.doit(**hints) return rv def evalf(self, prec=None, **options): return self.doit().evalf(prec, **options) n = evalf @property def variables(self): """The variables to be evaluated""" return self._args[1] bound_symbols = variables @property def expr(self): """The expression on which the substitution operates""" return self._args[0] @property def point(self): """The values for which the variables are to be substituted""" return self._args[2] @property def free_symbols(self): return (self.expr.free_symbols - set(self.variables) | set(self.point.free_symbols)) @property def expr_free_symbols(self): return (self.expr.expr_free_symbols - set(self.variables) | set(self.point.expr_free_symbols)) def __eq__(self, other): if not isinstance(other, Subs): return False return self._hashable_content() == other._hashable_content() def __ne__(self, other): return not(self == other) def __hash__(self): return super(Subs, self).__hash__() def _hashable_content(self): return (self._expr.xreplace(self.canonical_variables), ) + tuple(ordered([(v, p) for v, p in zip(self.variables, self.point) if not self.expr.has(v)])) def _eval_subs(self, old, new): # Subs doit will do the variables in order; the semantics # of subs for Subs is have the following invariant for # Subs object foo: # foo.doit().subs(reps) == foo.subs(reps).doit() pt = list(self.point) if old in self.variables: if _atomic(new) == set([new]) and not any( i.has(new) for i in self.args): # the substitution is neutral return self.xreplace({old: new}) # any occurance of old before this point will get # handled by replacements from here on i = self.variables.index(old) for j in range(i, len(self.variables)): pt[j] = pt[j]._subs(old, new) return self.func(self.expr, self.variables, pt) v = [i._subs(old, new) for i in self.variables] if v != list(self.variables): return self.func(self.expr, self.variables + (old,), pt + [new]) expr = self.expr._subs(old, new) pt = [i._subs(old, new) for i in self.point] return self.func(expr, v, pt) def _eval_derivative(self, s): # Apply the chain rule of the derivative on the substitution variables: val = Add.fromiter(p.diff(s) * Subs(self.expr.diff(v), self.variables, self.point).doit() for v, p in zip(self.variables, self.point)) # Check if there are free symbols in `self.expr`: # First get the `expr_free_symbols`, which returns the free symbols # that are directly contained in an expression node (i.e. stop # searching if the node isn't an expression). At this point turn the # expressions into `free_symbols` and check if there are common free # symbols in `self.expr` and the deriving factor. fs1 = {j for i in self.expr_free_symbols for j in i.free_symbols} if len(fs1 & s.free_symbols) > 0: val += Subs(self.expr.diff(s), self.variables, self.point).doit() return val def _eval_nseries(self, x, n, logx): if x in self.point: # x is the variable being substituted into apos = self.point.index(x) other = self.variables[apos] else: other = x arg = self.expr.nseries(other, n=n, logx=logx) o = arg.getO() terms = Add.make_args(arg.removeO()) rv = Add(*[self.func(a, *self.args[1:]) for a in terms]) if o: rv += o.subs(other, x) return rv def _eval_as_leading_term(self, x): if x in self.point: ipos = self.point.index(x) xvar = self.variables[ipos] return self.expr.as_leading_term(xvar) if x in self.variables: # if `x` is a dummy variable, it means it won't exist after the # substitution has been performed: return self # The variable is independent of the substitution: return self.expr.as_leading_term(x) def diff(f, *symbols, **kwargs): """ Differentiate f with respect to symbols. This is just a wrapper to unify .diff() and the Derivative class; its interface is similar to that of integrate(). You can use the same shortcuts for multiple variables as with Derivative. For example, diff(f(x), x, x, x) and diff(f(x), x, 3) both return the third derivative of f(x). You can pass evaluate=False to get an unevaluated Derivative class. Note that if there are 0 symbols (such as diff(f(x), x, 0), then the result will be the function (the zeroth derivative), even if evaluate=False. Examples ======== >>> from sympy import sin, cos, Function, diff >>> from sympy.abc import x, y >>> f = Function('f') >>> diff(sin(x), x) cos(x) >>> diff(f(x), x, x, x) Derivative(f(x), (x, 3)) >>> diff(f(x), x, 3) Derivative(f(x), (x, 3)) >>> diff(sin(x)*cos(y), x, 2, y, 2) sin(x)*cos(y) >>> type(diff(sin(x), x)) cos >>> type(diff(sin(x), x, evaluate=False)) <class 'sympy.core.function.Derivative'> >>> type(diff(sin(x), x, 0)) sin >>> type(diff(sin(x), x, 0, evaluate=False)) sin >>> diff(sin(x)) cos(x) >>> diff(sin(x*y)) Traceback (most recent call last): ... ValueError: specify differentiation variables to differentiate sin(x*y) Note that ``diff(sin(x))`` syntax is meant only for convenience in interactive sessions and should be avoided in library code. References ========== http://reference.wolfram.com/legacy/v5_2/Built-inFunctions/AlgebraicComputation/Calculus/D.html See Also ======== Derivative sympy.geometry.util.idiff: computes the derivative implicitly """ if hasattr(f, 'diff'): return f.diff(*symbols, **kwargs) kwargs.setdefault('evaluate', True) return Derivative(f, *symbols, **kwargs) def expand(e, deep=True, modulus=None, power_base=True, power_exp=True, mul=True, log=True, multinomial=True, basic=True, **hints): r""" Expand an expression using methods given as hints. Hints evaluated unless explicitly set to False are: ``basic``, ``log``, ``multinomial``, ``mul``, ``power_base``, and ``power_exp`` The following hints are supported but not applied unless set to True: ``complex``, ``func``, and ``trig``. In addition, the following meta-hints are supported by some or all of the other hints: ``frac``, ``numer``, ``denom``, ``modulus``, and ``force``. ``deep`` is supported by all hints. Additionally, subclasses of Expr may define their own hints or meta-hints. The ``basic`` hint is used for any special rewriting of an object that should be done automatically (along with the other hints like ``mul``) when expand is called. This is a catch-all hint to handle any sort of expansion that may not be described by the existing hint names. To use this hint an object should override the ``_eval_expand_basic`` method. Objects may also define their own expand methods, which are not run by default. See the API section below. If ``deep`` is set to ``True`` (the default), things like arguments of functions are recursively expanded. Use ``deep=False`` to only expand on the top level. If the ``force`` hint is used, assumptions about variables will be ignored in making the expansion. Hints ===== These hints are run by default mul --- Distributes multiplication over addition: >>> from sympy import cos, exp, sin >>> from sympy.abc import x, y, z >>> (y*(x + z)).expand(mul=True) x*y + y*z multinomial ----------- Expand (x + y + ...)**n where n is a positive integer. >>> ((x + y + z)**2).expand(multinomial=True) x**2 + 2*x*y + 2*x*z + y**2 + 2*y*z + z**2 power_exp --------- Expand addition in exponents into multiplied bases. >>> exp(x + y).expand(power_exp=True) exp(x)*exp(y) >>> (2**(x + y)).expand(power_exp=True) 2**x*2**y power_base ---------- Split powers of multiplied bases. This only happens by default if assumptions allow, or if the ``force`` meta-hint is used: >>> ((x*y)**z).expand(power_base=True) (x*y)**z >>> ((x*y)**z).expand(power_base=True, force=True) x**z*y**z >>> ((2*y)**z).expand(power_base=True) 2**z*y**z Note that in some cases where this expansion always holds, SymPy performs it automatically: >>> (x*y)**2 x**2*y**2 log --- Pull out power of an argument as a coefficient and split logs products into sums of logs. Note that these only work if the arguments of the log function have the proper assumptions--the arguments must be positive and the exponents must be real--or else the ``force`` hint must be True: >>> from sympy import log, symbols >>> log(x**2*y).expand(log=True) log(x**2*y) >>> log(x**2*y).expand(log=True, force=True) 2*log(x) + log(y) >>> x, y = symbols('x,y', positive=True) >>> log(x**2*y).expand(log=True) 2*log(x) + log(y) basic ----- This hint is intended primarily as a way for custom subclasses to enable expansion by default. These hints are not run by default: complex ------- Split an expression into real and imaginary parts. >>> x, y = symbols('x,y') >>> (x + y).expand(complex=True) re(x) + re(y) + I*im(x) + I*im(y) >>> cos(x).expand(complex=True) -I*sin(re(x))*sinh(im(x)) + cos(re(x))*cosh(im(x)) Note that this is just a wrapper around ``as_real_imag()``. Most objects that wish to redefine ``_eval_expand_complex()`` should consider redefining ``as_real_imag()`` instead. func ---- Expand other functions. >>> from sympy import gamma >>> gamma(x + 1).expand(func=True) x*gamma(x) trig ---- Do trigonometric expansions. >>> cos(x + y).expand(trig=True) -sin(x)*sin(y) + cos(x)*cos(y) >>> sin(2*x).expand(trig=True) 2*sin(x)*cos(x) Note that the forms of ``sin(n*x)`` and ``cos(n*x)`` in terms of ``sin(x)`` and ``cos(x)`` are not unique, due to the identity `\sin^2(x) + \cos^2(x) = 1`. The current implementation uses the form obtained from Chebyshev polynomials, but this may change. See `this MathWorld article <http://mathworld.wolfram.com/Multiple-AngleFormulas.html>`_ for more information. Notes ===== - You can shut off unwanted methods:: >>> (exp(x + y)*(x + y)).expand() x*exp(x)*exp(y) + y*exp(x)*exp(y) >>> (exp(x + y)*(x + y)).expand(power_exp=False) x*exp(x + y) + y*exp(x + y) >>> (exp(x + y)*(x + y)).expand(mul=False) (x + y)*exp(x)*exp(y) - Use deep=False to only expand on the top level:: >>> exp(x + exp(x + y)).expand() exp(x)*exp(exp(x)*exp(y)) >>> exp(x + exp(x + y)).expand(deep=False) exp(x)*exp(exp(x + y)) - Hints are applied in an arbitrary, but consistent order (in the current implementation, they are applied in alphabetical order, except multinomial comes before mul, but this may change). Because of this, some hints may prevent expansion by other hints if they are applied first. For example, ``mul`` may distribute multiplications and prevent ``log`` and ``power_base`` from expanding them. Also, if ``mul`` is applied before ``multinomial`, the expression might not be fully distributed. The solution is to use the various ``expand_hint`` helper functions or to use ``hint=False`` to this function to finely control which hints are applied. Here are some examples:: >>> from sympy import expand, expand_mul, expand_power_base >>> x, y, z = symbols('x,y,z', positive=True) >>> expand(log(x*(y + z))) log(x) + log(y + z) Here, we see that ``log`` was applied before ``mul``. To get the mul expanded form, either of the following will work:: >>> expand_mul(log(x*(y + z))) log(x*y + x*z) >>> expand(log(x*(y + z)), log=False) log(x*y + x*z) A similar thing can happen with the ``power_base`` hint:: >>> expand((x*(y + z))**x) (x*y + x*z)**x To get the ``power_base`` expanded form, either of the following will work:: >>> expand((x*(y + z))**x, mul=False) x**x*(y + z)**x >>> expand_power_base((x*(y + z))**x) x**x*(y + z)**x >>> expand((x + y)*y/x) y + y**2/x The parts of a rational expression can be targeted:: >>> expand((x + y)*y/x/(x + 1), frac=True) (x*y + y**2)/(x**2 + x) >>> expand((x + y)*y/x/(x + 1), numer=True) (x*y + y**2)/(x*(x + 1)) >>> expand((x + y)*y/x/(x + 1), denom=True) y*(x + y)/(x**2 + x) - The ``modulus`` meta-hint can be used to reduce the coefficients of an expression post-expansion:: >>> expand((3*x + 1)**2) 9*x**2 + 6*x + 1 >>> expand((3*x + 1)**2, modulus=5) 4*x**2 + x + 1 - Either ``expand()`` the function or ``.expand()`` the method can be used. Both are equivalent:: >>> expand((x + 1)**2) x**2 + 2*x + 1 >>> ((x + 1)**2).expand() x**2 + 2*x + 1 API === Objects can define their own expand hints by defining ``_eval_expand_hint()``. The function should take the form:: def _eval_expand_hint(self, **hints): # Only apply the method to the top-level expression ... See also the example below. Objects should define ``_eval_expand_hint()`` methods only if ``hint`` applies to that specific object. The generic ``_eval_expand_hint()`` method defined in Expr will handle the no-op case. Each hint should be responsible for expanding that hint only. Furthermore, the expansion should be applied to the top-level expression only. ``expand()`` takes care of the recursion that happens when ``deep=True``. You should only call ``_eval_expand_hint()`` methods directly if you are 100% sure that the object has the method, as otherwise you are liable to get unexpected ``AttributeError``s. Note, again, that you do not need to recursively apply the hint to args of your object: this is handled automatically by ``expand()``. ``_eval_expand_hint()`` should generally not be used at all outside of an ``_eval_expand_hint()`` method. If you want to apply a specific expansion from within another method, use the public ``expand()`` function, method, or ``expand_hint()`` functions. In order for expand to work, objects must be rebuildable by their args, i.e., ``obj.func(*obj.args) == obj`` must hold. Expand methods are passed ``**hints`` so that expand hints may use 'metahints'--hints that control how different expand methods are applied. For example, the ``force=True`` hint described above that causes ``expand(log=True)`` to ignore assumptions is such a metahint. The ``deep`` meta-hint is handled exclusively by ``expand()`` and is not passed to ``_eval_expand_hint()`` methods. Note that expansion hints should generally be methods that perform some kind of 'expansion'. For hints that simply rewrite an expression, use the .rewrite() API. Examples ======== >>> from sympy import Expr, sympify >>> class MyClass(Expr): ... def __new__(cls, *args): ... args = sympify(args) ... return Expr.__new__(cls, *args) ... ... def _eval_expand_double(self, **hints): ... ''' ... Doubles the args of MyClass. ... ... If there more than four args, doubling is not performed, ... unless force=True is also used (False by default). ... ''' ... force = hints.pop('force', False) ... if not force and len(self.args) > 4: ... return self ... return self.func(*(self.args + self.args)) ... >>> a = MyClass(1, 2, MyClass(3, 4)) >>> a MyClass(1, 2, MyClass(3, 4)) >>> a.expand(double=True) MyClass(1, 2, MyClass(3, 4, 3, 4), 1, 2, MyClass(3, 4, 3, 4)) >>> a.expand(double=True, deep=False) MyClass(1, 2, MyClass(3, 4), 1, 2, MyClass(3, 4)) >>> b = MyClass(1, 2, 3, 4, 5) >>> b.expand(double=True) MyClass(1, 2, 3, 4, 5) >>> b.expand(double=True, force=True) MyClass(1, 2, 3, 4, 5, 1, 2, 3, 4, 5) See Also ======== expand_log, expand_mul, expand_multinomial, expand_complex, expand_trig, expand_power_base, expand_power_exp, expand_func, hyperexpand """ # don't modify this; modify the Expr.expand method hints['power_base'] = power_base hints['power_exp'] = power_exp hints['mul'] = mul hints['log'] = log hints['multinomial'] = multinomial hints['basic'] = basic return sympify(e).expand(deep=deep, modulus=modulus, **hints) # This is a special application of two hints def _mexpand(expr, recursive=False): # expand multinomials and then expand products; this may not always # be sufficient to give a fully expanded expression (see # test_issue_8247_8354 in test_arit) if expr is None: return was = None while was != expr: was, expr = expr, expand_mul(expand_multinomial(expr)) if not recursive: break return expr # These are simple wrappers around single hints. def expand_mul(expr, deep=True): """ Wrapper around expand that only uses the mul hint. See the expand docstring for more information. Examples ======== >>> from sympy import symbols, expand_mul, exp, log >>> x, y = symbols('x,y', positive=True) >>> expand_mul(exp(x+y)*(x+y)*log(x*y**2)) x*exp(x + y)*log(x*y**2) + y*exp(x + y)*log(x*y**2) """ return sympify(expr).expand(deep=deep, mul=True, power_exp=False, power_base=False, basic=False, multinomial=False, log=False) def expand_multinomial(expr, deep=True): """ Wrapper around expand that only uses the multinomial hint. See the expand docstring for more information. Examples ======== >>> from sympy import symbols, expand_multinomial, exp >>> x, y = symbols('x y', positive=True) >>> expand_multinomial((x + exp(x + 1))**2) x**2 + 2*x*exp(x + 1) + exp(2*x + 2) """ return sympify(expr).expand(deep=deep, mul=False, power_exp=False, power_base=False, basic=False, multinomial=True, log=False) def expand_log(expr, deep=True, force=False): """ Wrapper around expand that only uses the log hint. See the expand docstring for more information. Examples ======== >>> from sympy import symbols, expand_log, exp, log >>> x, y = symbols('x,y', positive=True) >>> expand_log(exp(x+y)*(x+y)*log(x*y**2)) (x + y)*(log(x) + 2*log(y))*exp(x + y) """ return sympify(expr).expand(deep=deep, log=True, mul=False, power_exp=False, power_base=False, multinomial=False, basic=False, force=force) def expand_func(expr, deep=True): """ Wrapper around expand that only uses the func hint. See the expand docstring for more information. Examples ======== >>> from sympy import expand_func, gamma >>> from sympy.abc import x >>> expand_func(gamma(x + 2)) x*(x + 1)*gamma(x) """ return sympify(expr).expand(deep=deep, func=True, basic=False, log=False, mul=False, power_exp=False, power_base=False, multinomial=False) def expand_trig(expr, deep=True): """ Wrapper around expand that only uses the trig hint. See the expand docstring for more information. Examples ======== >>> from sympy import expand_trig, sin >>> from sympy.abc import x, y >>> expand_trig(sin(x+y)*(x+y)) (x + y)*(sin(x)*cos(y) + sin(y)*cos(x)) """ return sympify(expr).expand(deep=deep, trig=True, basic=False, log=False, mul=False, power_exp=False, power_base=False, multinomial=False) def expand_complex(expr, deep=True): """ Wrapper around expand that only uses the complex hint. See the expand docstring for more information. Examples ======== >>> from sympy import expand_complex, exp, sqrt, I >>> from sympy.abc import z >>> expand_complex(exp(z)) I*exp(re(z))*sin(im(z)) + exp(re(z))*cos(im(z)) >>> expand_complex(sqrt(I)) sqrt(2)/2 + sqrt(2)*I/2 See Also ======== Expr.as_real_imag """ return sympify(expr).expand(deep=deep, complex=True, basic=False, log=False, mul=False, power_exp=False, power_base=False, multinomial=False) def expand_power_base(expr, deep=True, force=False): """ Wrapper around expand that only uses the power_base hint. See the expand docstring for more information. A wrapper to expand(power_base=True) which separates a power with a base that is a Mul into a product of powers, without performing any other expansions, provided that assumptions about the power's base and exponent allow. deep=False (default is True) will only apply to the top-level expression. force=True (default is False) will cause the expansion to ignore assumptions about the base and exponent. When False, the expansion will only happen if the base is non-negative or the exponent is an integer. >>> from sympy.abc import x, y, z >>> from sympy import expand_power_base, sin, cos, exp >>> (x*y)**2 x**2*y**2 >>> (2*x)**y (2*x)**y >>> expand_power_base(_) 2**y*x**y >>> expand_power_base((x*y)**z) (x*y)**z >>> expand_power_base((x*y)**z, force=True) x**z*y**z >>> expand_power_base(sin((x*y)**z), deep=False) sin((x*y)**z) >>> expand_power_base(sin((x*y)**z), force=True) sin(x**z*y**z) >>> expand_power_base((2*sin(x))**y + (2*cos(x))**y) 2**y*sin(x)**y + 2**y*cos(x)**y >>> expand_power_base((2*exp(y))**x) 2**x*exp(y)**x >>> expand_power_base((2*cos(x))**y) 2**y*cos(x)**y Notice that sums are left untouched. If this is not the desired behavior, apply full ``expand()`` to the expression: >>> expand_power_base(((x+y)*z)**2) z**2*(x + y)**2 >>> (((x+y)*z)**2).expand() x**2*z**2 + 2*x*y*z**2 + y**2*z**2 >>> expand_power_base((2*y)**(1+z)) 2**(z + 1)*y**(z + 1) >>> ((2*y)**(1+z)).expand() 2*2**z*y*y**z """ return sympify(expr).expand(deep=deep, log=False, mul=False, power_exp=False, power_base=True, multinomial=False, basic=False, force=force) def expand_power_exp(expr, deep=True): """ Wrapper around expand that only uses the power_exp hint. See the expand docstring for more information. Examples ======== >>> from sympy import expand_power_exp >>> from sympy.abc import x, y >>> expand_power_exp(x**(y + 2)) x**2*x**y """ return sympify(expr).expand(deep=deep, complex=False, basic=False, log=False, mul=False, power_exp=True, power_base=False, multinomial=False) def count_ops(expr, visual=False): """ Return a representation (integer or expression) of the operations in expr. If ``visual`` is ``False`` (default) then the sum of the coefficients of the visual expression will be returned. If ``visual`` is ``True`` then the number of each type of operation is shown with the core class types (or their virtual equivalent) multiplied by the number of times they occur. If expr is an iterable, the sum of the op counts of the items will be returned. Examples ======== >>> from sympy.abc import a, b, x, y >>> from sympy import sin, count_ops Although there isn't a SUB object, minus signs are interpreted as either negations or subtractions: >>> (x - y).count_ops(visual=True) SUB >>> (-x).count_ops(visual=True) NEG Here, there are two Adds and a Pow: >>> (1 + a + b**2).count_ops(visual=True) 2*ADD + POW In the following, an Add, Mul, Pow and two functions: >>> (sin(x)*x + sin(x)**2).count_ops(visual=True) ADD + MUL + POW + 2*SIN for a total of 5: >>> (sin(x)*x + sin(x)**2).count_ops(visual=False) 5 Note that "what you type" is not always what you get. The expression 1/x/y is translated by sympy into 1/(x*y) so it gives a DIV and MUL rather than two DIVs: >>> (1/x/y).count_ops(visual=True) DIV + MUL The visual option can be used to demonstrate the difference in operations for expressions in different forms. Here, the Horner representation is compared with the expanded form of a polynomial: >>> eq=x*(1 + x*(2 + x*(3 + x))) >>> count_ops(eq.expand(), visual=True) - count_ops(eq, visual=True) -MUL + 3*POW The count_ops function also handles iterables: >>> count_ops([x, sin(x), None, True, x + 2], visual=False) 2 >>> count_ops([x, sin(x), None, True, x + 2], visual=True) ADD + SIN >>> count_ops({x: sin(x), x + 2: y + 1}, visual=True) 2*ADD + SIN """ from sympy import Integral, Symbol from sympy.core.relational import Relational from sympy.simplify.radsimp import fraction from sympy.logic.boolalg import BooleanFunction from sympy.utilities.misc import func_name expr = sympify(expr) if isinstance(expr, Expr) and not expr.is_Relational: ops = [] args = [expr] NEG = Symbol('NEG') DIV = Symbol('DIV') SUB = Symbol('SUB') ADD = Symbol('ADD') while args: a = args.pop() # XXX: This is a hack to support non-Basic args if isinstance(a, string_types): continue if a.is_Rational: #-1/3 = NEG + DIV if a is not S.One: if a.p < 0: ops.append(NEG) if a.q != 1: ops.append(DIV) continue elif a.is_Mul or a.is_MatMul: if _coeff_isneg(a): ops.append(NEG) if a.args[0] is S.NegativeOne: a = a.as_two_terms()[1] else: a = -a n, d = fraction(a) if n.is_Integer: ops.append(DIV) if n < 0: ops.append(NEG) args.append(d) continue # won't be -Mul but could be Add elif d is not S.One: if not d.is_Integer: args.append(d) ops.append(DIV) args.append(n) continue # could be -Mul elif a.is_Add or a.is_MatAdd: aargs = list(a.args) negs = 0 for i, ai in enumerate(aargs): if _coeff_isneg(ai): negs += 1 args.append(-ai) if i > 0: ops.append(SUB) else: args.append(ai) if i > 0: ops.append(ADD) if negs == len(aargs): # -x - y = NEG + SUB ops.append(NEG) elif _coeff_isneg(aargs[0]): # -x + y = SUB, but already recorded ADD ops.append(SUB - ADD) continue if a.is_Pow and a.exp is S.NegativeOne: ops.append(DIV) args.append(a.base) # won't be -Mul but could be Add continue if (a.is_Mul or a.is_Pow or a.is_Function or isinstance(a, Derivative) or isinstance(a, Integral)): o = Symbol(a.func.__name__.upper()) # count the args if (a.is_Mul or isinstance(a, LatticeOp)): ops.append(o*(len(a.args) - 1)) else: ops.append(o) if not a.is_Symbol: args.extend(a.args) elif type(expr) is dict: ops = [count_ops(k, visual=visual) + count_ops(v, visual=visual) for k, v in expr.items()] elif iterable(expr): ops = [count_ops(i, visual=visual) for i in expr] elif isinstance(expr, (Relational, BooleanFunction)): ops = [] for arg in expr.args: ops.append(count_ops(arg, visual=True)) o = Symbol(func_name(expr, short=True).upper()) ops.append(o) elif not isinstance(expr, Basic): ops = [] else: # it's Basic not isinstance(expr, Expr): if not isinstance(expr, Basic): raise TypeError("Invalid type of expr") else: ops = [] args = [expr] while args: a = args.pop() # XXX: This is a hack to support non-Basic args if isinstance(a, string_types): continue if a.args: o = Symbol(a.func.__name__.upper()) if a.is_Boolean: ops.append(o*(len(a.args)-1)) else: ops.append(o) args.extend(a.args) if not ops: if visual: return S.Zero return 0 ops = Add(*ops) if visual: return ops if ops.is_Number: return int(ops) return sum(int((a.args or [1])[0]) for a in Add.make_args(ops)) def nfloat(expr, n=15, exponent=False): """Make all Rationals in expr Floats except those in exponents (unless the exponents flag is set to True). Examples ======== >>> from sympy.core.function import nfloat >>> from sympy.abc import x, y >>> from sympy import cos, pi, sqrt >>> nfloat(x**4 + x/2 + cos(pi/3) + 1 + sqrt(y)) x**4 + 0.5*x + sqrt(y) + 1.5 >>> nfloat(x**4 + sqrt(y), exponent=True) x**4.0 + y**0.5 """ from sympy.core.power import Pow from sympy.polys.rootoftools import RootOf if iterable(expr, exclude=string_types): if isinstance(expr, (dict, Dict)): return type(expr)([(k, nfloat(v, n, exponent)) for k, v in list(expr.items())]) return type(expr)([nfloat(a, n, exponent) for a in expr]) rv = sympify(expr) if rv.is_Number: return Float(rv, n) elif rv.is_number: # evalf doesn't always set the precision rv = rv.n(n) if rv.is_Number: rv = Float(rv.n(n), n) else: pass # pure_complex(rv) is likely True return rv # watch out for RootOf instances that don't like to have # their exponents replaced with Dummies and also sometimes have # problems with evaluating at low precision (issue 6393) rv = rv.xreplace({ro: ro.n(n) for ro in rv.atoms(RootOf)}) if not exponent: reps = [(p, Pow(p.base, Dummy())) for p in rv.atoms(Pow)] rv = rv.xreplace(dict(reps)) rv = rv.n(n) if not exponent: rv = rv.xreplace({d.exp: p.exp for p, d in reps}) else: # Pow._eval_evalf special cases Integer exponents so if # exponent is suppose to be handled we have to do so here rv = rv.xreplace(Transform( lambda x: Pow(x.base, Float(x.exp, n)), lambda x: x.is_Pow and x.exp.is_Integer)) return rv.xreplace(Transform( lambda x: x.func(*nfloat(x.args, n, exponent)), lambda x: isinstance(x, Function))) from sympy.core.symbol import Dummy, Symbol

ddd2493ea1aae6cc2fb7fe0ab47b0ef3e9a18b9eb7a766bb8b45e24981937b48

from __future__ import print_function, division from collections import defaultdict from functools import cmp_to_key from .basic import Basic from .compatibility import reduce, is_sequence, range from .logic import _fuzzy_group, fuzzy_or, fuzzy_not from .singleton import S from .operations import AssocOp from .cache import cacheit from .numbers import ilcm, igcd from .expr import Expr # Key for sorting commutative args in canonical order _args_sortkey = cmp_to_key(Basic.compare) def _addsort(args): # in-place sorting of args args.sort(key=_args_sortkey) def _unevaluated_Add(*args): """Return a well-formed unevaluated Add: Numbers are collected and put in slot 0 and args are sorted. Use this when args have changed but you still want to return an unevaluated Add. Examples ======== >>> from sympy.core.add import _unevaluated_Add as uAdd >>> from sympy import S, Add >>> from sympy.abc import x, y >>> a = uAdd(*[S(1.0), x, S(2)]) >>> a.args[0] 3.00000000000000 >>> a.args[1] x Beyond the Number being in slot 0, there is no other assurance of order for the arguments since they are hash sorted. So, for testing purposes, output produced by this in some other function can only be tested against the output of this function or as one of several options: >>> opts = (Add(x, y, evaluated=False), Add(y, x, evaluated=False)) >>> a = uAdd(x, y) >>> assert a in opts and a == uAdd(x, y) >>> uAdd(x + 1, x + 2) x + x + 3 """ args = list(args) newargs = [] co = S.Zero while args: a = args.pop() if a.is_Add: # this will keep nesting from building up # so that x + (x + 1) -> x + x + 1 (3 args) args.extend(a.args) elif a.is_Number: co += a else: newargs.append(a) _addsort(newargs) if co: newargs.insert(0, co) return Add._from_args(newargs) class Add(Expr, AssocOp): __slots__ = [] is_Add = True @classmethod def flatten(cls, seq): """ Takes the sequence "seq" of nested Adds and returns a flatten list. Returns: (commutative_part, noncommutative_part, order_symbols) Applies associativity, all terms are commutable with respect to addition. NB: the removal of 0 is already handled by AssocOp.__new__ See also ======== sympy.core.mul.Mul.flatten """ from sympy.calculus.util import AccumBounds from sympy.matrices.expressions import MatrixExpr from sympy.tensor.tensor import TensExpr rv = None if len(seq) == 2: a, b = seq if b.is_Rational: a, b = b, a if a.is_Rational: if b.is_Mul: rv = [a, b], [], None if rv: if all(s.is_commutative for s in rv[0]): return rv return [], rv[0], None terms = {} # term -> coeff # e.g. x**2 -> 5 for ... + 5*x**2 + ... coeff = S.Zero # coefficient (Number or zoo) to always be in slot 0 # e.g. 3 + ... order_factors = [] for o in seq: # O(x) if o.is_Order: for o1 in order_factors: if o1.contains(o): o = None break if o is None: continue order_factors = [o] + [ o1 for o1 in order_factors if not o.contains(o1)] continue # 3 or NaN elif o.is_Number: if (o is S.NaN or coeff is S.ComplexInfinity and o.is_finite is False): # we know for sure the result will be nan return [S.NaN], [], None if coeff.is_Number: coeff += o if coeff is S.NaN: # we know for sure the result will be nan return [S.NaN], [], None continue elif isinstance(o, AccumBounds): coeff = o.__add__(coeff) continue elif isinstance(o, MatrixExpr): # can't add 0 to Matrix so make sure coeff is not 0 coeff = o.__add__(coeff) if coeff else o continue elif isinstance(o, TensExpr): coeff = o.__add__(coeff) if coeff else o continue elif o is S.ComplexInfinity: if coeff.is_finite is False: # we know for sure the result will be nan return [S.NaN], [], None coeff = S.ComplexInfinity continue # Add([...]) elif o.is_Add: # NB: here we assume Add is always commutative seq.extend(o.args) # TODO zerocopy? continue # Mul([...]) elif o.is_Mul: c, s = o.as_coeff_Mul() # check for unevaluated Pow, e.g. 2**3 or 2**(-1/2) elif o.is_Pow: b, e = o.as_base_exp() if b.is_Number and (e.is_Integer or (e.is_Rational and e.is_negative)): seq.append(b**e) continue c, s = S.One, o else: # everything else c = S.One s = o # now we have: # o = c*s, where # # c is a Number # s is an expression with number factor extracted # let's collect terms with the same s, so e.g. # 2*x**2 + 3*x**2 -> 5*x**2 if s in terms: terms[s] += c if terms[s] is S.NaN: # we know for sure the result will be nan return [S.NaN], [], None else: terms[s] = c # now let's construct new args: # [2*x**2, x**3, 7*x**4, pi, ...] newseq = [] noncommutative = False for s, c in terms.items(): # 0*s if c is S.Zero: continue # 1*s elif c is S.One: newseq.append(s) # c*s else: if s.is_Mul: # Mul, already keeps its arguments in perfect order. # so we can simply put c in slot0 and go the fast way. cs = s._new_rawargs(*((c,) + s.args)) newseq.append(cs) elif s.is_Add: # we just re-create the unevaluated Mul newseq.append(Mul(c, s, evaluate=False)) else: # alternatively we have to call all Mul's machinery (slow) newseq.append(Mul(c, s)) noncommutative = noncommutative or not s.is_commutative # oo, -oo if coeff is S.Infinity: newseq = [f for f in newseq if not (f.is_nonnegative or f.is_real and f.is_finite)] elif coeff is S.NegativeInfinity: newseq = [f for f in newseq if not (f.is_nonpositive or f.is_real and f.is_finite)] if coeff is S.ComplexInfinity: # zoo might be # infinite_real + finite_im # finite_real + infinite_im # infinite_real + infinite_im # addition of a finite real or imaginary number won't be able to # change the zoo nature; adding an infinite qualtity would result # in a NaN condition if it had sign opposite of the infinite # portion of zoo, e.g., infinite_real - infinite_real. newseq = [c for c in newseq if not (c.is_finite and c.is_real is not None)] # process O(x) if order_factors: newseq2 = [] for t in newseq: for o in order_factors: # x + O(x) -> O(x) if o.contains(t): t = None break # x + O(x**2) -> x + O(x**2) if t is not None: newseq2.append(t) newseq = newseq2 + order_factors # 1 + O(1) -> O(1) for o in order_factors: if o.contains(coeff): coeff = S.Zero break # order args canonically _addsort(newseq) # current code expects coeff to be first if coeff is not S.Zero: newseq.insert(0, coeff) # we are done if noncommutative: return [], newseq, None else: return newseq, [], None @classmethod def class_key(cls): """Nice order of classes""" return 3, 1, cls.__name__ def as_coefficients_dict(a): """Return a dictionary mapping terms to their Rational coefficient. Since the dictionary is a defaultdict, inquiries about terms which were not present will return a coefficient of 0. If an expression is not an Add it is considered to have a single term. Examples ======== >>> from sympy.abc import a, x >>> (3*x + a*x + 4).as_coefficients_dict() {1: 4, x: 3, a*x: 1} >>> _[a] 0 >>> (3*a*x).as_coefficients_dict() {a*x: 3} """ d = defaultdict(list) for ai in a.args: c, m = ai.as_coeff_Mul() d[m].append(c) for k, v in d.items(): if len(v) == 1: d[k] = v[0] else: d[k] = Add(*v) di = defaultdict(int) di.update(d) return di @cacheit def as_coeff_add(self, *deps): """ Returns a tuple (coeff, args) where self is treated as an Add and coeff is the Number term and args is a tuple of all other terms. Examples ======== >>> from sympy.abc import x >>> (7 + 3*x).as_coeff_add() (7, (3*x,)) >>> (7*x).as_coeff_add() (0, (7*x,)) """ if deps: l1 = [] l2 = [] for f in self.args: if f.has(*deps): l2.append(f) else: l1.append(f) return self._new_rawargs(*l1), tuple(l2) coeff, notrat = self.args[0].as_coeff_add() if coeff is not S.Zero: return coeff, notrat + self.args[1:] return S.Zero, self.args def as_coeff_Add(self, rational=False): """Efficiently extract the coefficient of a summation. """ coeff, args = self.args[0], self.args[1:] if coeff.is_Number and not rational or coeff.is_Rational: return coeff, self._new_rawargs(*args) return S.Zero, self # Note, we intentionally do not implement Add.as_coeff_mul(). Rather, we # let Expr.as_coeff_mul() just always return (S.One, self) for an Add. See # issue 5524. def _eval_power(self, e): if e.is_Rational and self.is_number: from sympy.core.evalf import pure_complex from sympy.core.mul import _unevaluated_Mul from sympy.core.exprtools import factor_terms from sympy.core.function import expand_multinomial from sympy.functions.elementary.complexes import sign from sympy.functions.elementary.miscellaneous import sqrt ri = pure_complex(self) if ri: r, i = ri if e.q == 2: D = sqrt(r**2 + i**2) if D.is_Rational: # (r, i, D) is a Pythagorean triple root = sqrt(factor_terms((D - r)/2))**e.p return root*expand_multinomial(( # principle value (D + r)/abs(i) + sign(i)*S.ImaginaryUnit)**e.p) elif e == -1: return _unevaluated_Mul( r - i*S.ImaginaryUnit, 1/(r**2 + i**2)) @cacheit def _eval_derivative(self, s): return self.func(*[a.diff(s) for a in self.args]) def _eval_nseries(self, x, n, logx): terms = [t.nseries(x, n=n, logx=logx) for t in self.args] return self.func(*terms) def _matches_simple(self, expr, repl_dict): # handle (w+3).matches('x+5') -> {w: x+2} coeff, terms = self.as_coeff_add() if len(terms) == 1: return terms[0].matches(expr - coeff, repl_dict) return def matches(self, expr, repl_dict={}, old=False): return AssocOp._matches_commutative(self, expr, repl_dict, old) @staticmethod def _combine_inverse(lhs, rhs): """ Returns lhs - rhs, but treats oo like a symbol so oo - oo returns 0, instead of a nan. """ from sympy.core.function import expand_mul from sympy.core.symbol import Dummy inf = (S.Infinity, S.NegativeInfinity) if lhs.has(*inf) or rhs.has(*inf): oo = Dummy('oo') reps = { S.Infinity: oo, S.NegativeInfinity: -oo} ireps = dict([(v, k) for k, v in reps.items()]) eq = expand_mul(lhs.xreplace(reps) - rhs.xreplace(reps)) if eq.has(oo): eq = eq.replace( lambda x: x.is_Pow and x.base == oo, lambda x: x.base) return eq.xreplace(ireps) else: return expand_mul(lhs - rhs) @cacheit def as_two_terms(self): """Return head and tail of self. This is the most efficient way to get the head and tail of an expression. - if you want only the head, use self.args[0]; - if you want to process the arguments of the tail then use self.as_coef_add() which gives the head and a tuple containing the arguments of the tail when treated as an Add. - if you want the coefficient when self is treated as a Mul then use self.as_coeff_mul()[0] >>> from sympy.abc import x, y >>> (3*x - 2*y + 5).as_two_terms() (5, 3*x - 2*y) """ return self.args[0], self._new_rawargs(*self.args[1:]) def as_numer_denom(self): # clear rational denominator content, expr = self.primitive() ncon, dcon = content.as_numer_denom() # collect numerators and denominators of the terms nd = defaultdict(list) for f in expr.args: ni, di = f.as_numer_denom() nd[di].append(ni) # check for quick exit if len(nd) == 1: d, n = nd.popitem() return self.func( *[_keep_coeff(ncon, ni) for ni in n]), _keep_coeff(dcon, d) # sum up the terms having a common denominator for d, n in nd.items(): if len(n) == 1: nd[d] = n[0] else: nd[d] = self.func(*n) # assemble single numerator and denominator denoms, numers = [list(i) for i in zip(*iter(nd.items()))] n, d = self.func(*[Mul(*(denoms[:i] + [numers[i]] + denoms[i + 1:])) for i in range(len(numers))]), Mul(*denoms) return _keep_coeff(ncon, n), _keep_coeff(dcon, d) def _eval_is_polynomial(self, syms): return all(term._eval_is_polynomial(syms) for term in self.args) def _eval_is_rational_function(self, syms): return all(term._eval_is_rational_function(syms) for term in self.args) def _eval_is_algebraic_expr(self, syms): return all(term._eval_is_algebraic_expr(syms) for term in self.args) # assumption methods _eval_is_real = lambda self: _fuzzy_group( (a.is_real for a in self.args), quick_exit=True) _eval_is_complex = lambda self: _fuzzy_group( (a.is_complex for a in self.args), quick_exit=True) _eval_is_antihermitian = lambda self: _fuzzy_group( (a.is_antihermitian for a in self.args), quick_exit=True) _eval_is_finite = lambda self: _fuzzy_group( (a.is_finite for a in self.args), quick_exit=True) _eval_is_hermitian = lambda self: _fuzzy_group( (a.is_hermitian for a in self.args), quick_exit=True) _eval_is_integer = lambda self: _fuzzy_group( (a.is_integer for a in self.args), quick_exit=True) _eval_is_rational = lambda self: _fuzzy_group( (a.is_rational for a in self.args), quick_exit=True) _eval_is_algebraic = lambda self: _fuzzy_group( (a.is_algebraic for a in self.args), quick_exit=True) _eval_is_commutative = lambda self: _fuzzy_group( a.is_commutative for a in self.args) def _eval_is_imaginary(self): nz = [] im_I = [] for a in self.args: if a.is_real: if a.is_zero: pass elif a.is_zero is False: nz.append(a) else: return elif a.is_imaginary: im_I.append(a*S.ImaginaryUnit) elif (S.ImaginaryUnit*a).is_real: im_I.append(a*S.ImaginaryUnit) else: return b = self.func(*nz) if b.is_zero: return fuzzy_not(self.func(*im_I).is_zero) elif b.is_zero is False: return False def _eval_is_zero(self): if self.is_commutative is False: # issue 10528: there is no way to know if a nc symbol # is zero or not return nz = [] z = 0 im_or_z = False im = False for a in self.args: if a.is_real: if a.is_zero: z += 1 elif a.is_zero is False: nz.append(a) else: return elif a.is_imaginary: im = True elif (S.ImaginaryUnit*a).is_real: im_or_z = True else: return if z == len(self.args): return True if len(nz) == len(self.args): return None b = self.func(*nz) if b.is_zero: if not im_or_z and not im: return True if im and not im_or_z: return False if b.is_zero is False: return False def _eval_is_odd(self): l = [f for f in self.args if not (f.is_even is True)] if not l: return False if l[0].is_odd: return self._new_rawargs(*l[1:]).is_even def _eval_is_irrational(self): for t in self.args: a = t.is_irrational if a: others = list(self.args) others.remove(t) if all(x.is_rational is True for x in others): return True return None if a is None: return return False def _eval_is_positive(self): from sympy.core.exprtools import _monotonic_sign if self.is_number: return super(Add, self)._eval_is_positive() c, a = self.as_coeff_Add() if not c.is_zero: v = _monotonic_sign(a) if v is not None: s = v + c if s != self and s.is_positive and a.is_nonnegative: return True if len(self.free_symbols) == 1: v = _monotonic_sign(self) if v is not None and v != self and v.is_positive: return True pos = nonneg = nonpos = unknown_sign = False saw_INF = set() args = [a for a in self.args if not a.is_zero] if not args: return False for a in args: ispos = a.is_positive infinite = a.is_infinite if infinite: saw_INF.add(fuzzy_or((ispos, a.is_nonnegative))) if True in saw_INF and False in saw_INF: return if ispos: pos = True continue elif a.is_nonnegative: nonneg = True continue elif a.is_nonpositive: nonpos = True continue if infinite is None: return unknown_sign = True if saw_INF: if len(saw_INF) > 1: return return saw_INF.pop() elif unknown_sign: return elif not nonpos and not nonneg and pos: return True elif not nonpos and pos: return True elif not pos and not nonneg: return False def _eval_is_nonnegative(self): from sympy.core.exprtools import _monotonic_sign if not self.is_number: c, a = self.as_coeff_Add() if not c.is_zero and a.is_nonnegative: v = _monotonic_sign(a) if v is not None: s = v + c if s != self and s.is_nonnegative: return True if len(self.free_symbols) == 1: v = _monotonic_sign(self) if v is not None and v != self and v.is_nonnegative: return True def _eval_is_nonpositive(self): from sympy.core.exprtools import _monotonic_sign if not self.is_number: c, a = self.as_coeff_Add() if not c.is_zero and a.is_nonpositive: v = _monotonic_sign(a) if v is not None: s = v + c if s != self and s.is_nonpositive: return True if len(self.free_symbols) == 1: v = _monotonic_sign(self) if v is not None and v != self and v.is_nonpositive: return True def _eval_is_negative(self): from sympy.core.exprtools import _monotonic_sign if self.is_number: return super(Add, self)._eval_is_negative() c, a = self.as_coeff_Add() if not c.is_zero: v = _monotonic_sign(a) if v is not None: s = v + c if s != self and s.is_negative and a.is_nonpositive: return True if len(self.free_symbols) == 1: v = _monotonic_sign(self) if v is not None and v != self and v.is_negative: return True neg = nonpos = nonneg = unknown_sign = False saw_INF = set() args = [a for a in self.args if not a.is_zero] if not args: return False for a in args: isneg = a.is_negative infinite = a.is_infinite if infinite: saw_INF.add(fuzzy_or((isneg, a.is_nonpositive))) if True in saw_INF and False in saw_INF: return if isneg: neg = True continue elif a.is_nonpositive: nonpos = True continue elif a.is_nonnegative: nonneg = True continue if infinite is None: return unknown_sign = True if saw_INF: if len(saw_INF) > 1: return return saw_INF.pop() elif unknown_sign: return elif not nonneg and not nonpos and neg: return True elif not nonneg and neg: return True elif not neg and not nonpos: return False def _eval_subs(self, old, new): if not old.is_Add: if old is S.Infinity and -old in self.args: # foo - oo is foo + (-oo) internally return self.xreplace({-old: -new}) return None coeff_self, terms_self = self.as_coeff_Add() coeff_old, terms_old = old.as_coeff_Add() if coeff_self.is_Rational and coeff_old.is_Rational: if terms_self == terms_old: # (2 + a).subs( 3 + a, y) -> -1 + y return self.func(new, coeff_self, -coeff_old) if terms_self == -terms_old: # (2 + a).subs(-3 - a, y) -> -1 - y return self.func(-new, coeff_self, coeff_old) if coeff_self.is_Rational and coeff_old.is_Rational \ or coeff_self == coeff_old: args_old, args_self = self.func.make_args( terms_old), self.func.make_args(terms_self) if len(args_old) < len(args_self): # (a+b+c).subs(b+c,x) -> a+x self_set = set(args_self) old_set = set(args_old) if old_set < self_set: ret_set = self_set - old_set return self.func(new, coeff_self, -coeff_old, *[s._subs(old, new) for s in ret_set]) args_old = self.func.make_args( -terms_old) # (a+b+c+d).subs(-b-c,x) -> a-x+d old_set = set(args_old) if old_set < self_set: ret_set = self_set - old_set return self.func(-new, coeff_self, coeff_old, *[s._subs(old, new) for s in ret_set]) def removeO(self): args = [a for a in self.args if not a.is_Order] return self._new_rawargs(*args) def getO(self): args = [a for a in self.args if a.is_Order] if args: return self._new_rawargs(*args) @cacheit def extract_leading_order(self, symbols, point=None): """ Returns the leading term and its order. Examples ======== >>> from sympy.abc import x >>> (x + 1 + 1/x**5).extract_leading_order(x) ((x**(-5), O(x**(-5))),) >>> (1 + x).extract_leading_order(x) ((1, O(1)),) >>> (x + x**2).extract_leading_order(x) ((x, O(x)),) """ from sympy import Order lst = [] symbols = list(symbols if is_sequence(symbols) else [symbols]) if not point: point = [0]*len(symbols) seq = [(f, Order(f, *zip(symbols, point))) for f in self.args] for ef, of in seq: for e, o in lst: if o.contains(of) and o != of: of = None break if of is None: continue new_lst = [(ef, of)] for e, o in lst: if of.contains(o) and o != of: continue new_lst.append((e, o)) lst = new_lst return tuple(lst) def as_real_imag(self, deep=True, **hints): """ returns a tuple representing a complex number Examples ======== >>> from sympy import I >>> (7 + 9*I).as_real_imag() (7, 9) >>> ((1 + I)/(1 - I)).as_real_imag() (0, 1) >>> ((1 + 2*I)*(1 + 3*I)).as_real_imag() (-5, 5) """ sargs = self.args re_part, im_part = [], [] for term in sargs: re, im = term.as_real_imag(deep=deep) re_part.append(re) im_part.append(im) return (self.func(*re_part), self.func(*im_part)) def _eval_as_leading_term(self, x): from sympy import expand_mul, factor_terms old = self expr = expand_mul(self) if not expr.is_Add: return expr.as_leading_term(x) infinite = [t for t in expr.args if t.is_infinite] expr = expr.func(*[t.as_leading_term(x) for t in expr.args]).removeO() if not expr: # simple leading term analysis gave us 0 but we have to send # back a term, so compute the leading term (via series) return old.compute_leading_term(x) elif expr is S.NaN: return old.func._from_args(infinite) elif not expr.is_Add: return expr else: plain = expr.func(*[s for s, _ in expr.extract_leading_order(x)]) rv = factor_terms(plain, fraction=False) rv_simplify = rv.simplify() # if it simplifies to an x-free expression, return that; # tests don't fail if we don't but it seems nicer to do this if x not in rv_simplify.free_symbols: if rv_simplify.is_zero and plain.is_zero is not True: return (expr - plain)._eval_as_leading_term(x) return rv_simplify return rv def _eval_adjoint(self): return self.func(*[t.adjoint() for t in self.args]) def _eval_conjugate(self): return self.func(*[t.conjugate() for t in self.args]) def _eval_transpose(self): return self.func(*[t.transpose() for t in self.args]) def __neg__(self): return self*(-1) def _sage_(self): s = 0 for x in self.args: s += x._sage_() return s def primitive(self): """ Return ``(R, self/R)`` where ``R``` is the Rational GCD of ``self```. ``R`` is collected only from the leading coefficient of each term. Examples ======== >>> from sympy.abc import x, y >>> (2*x + 4*y).primitive() (2, x + 2*y) >>> (2*x/3 + 4*y/9).primitive() (2/9, 3*x + 2*y) >>> (2*x/3 + 4.2*y).primitive() (1/3, 2*x + 12.6*y) No subprocessing of term factors is performed: >>> ((2 + 2*x)*x + 2).primitive() (1, x*(2*x + 2) + 2) Recursive processing can be done with the ``as_content_primitive()`` method: >>> ((2 + 2*x)*x + 2).as_content_primitive() (2, x*(x + 1) + 1) See also: primitive() function in polytools.py """ terms = [] inf = False for a in self.args: c, m = a.as_coeff_Mul() if not c.is_Rational: c = S.One m = a inf = inf or m is S.ComplexInfinity terms.append((c.p, c.q, m)) if not inf: ngcd = reduce(igcd, [t[0] for t in terms], 0) dlcm = reduce(ilcm, [t[1] for t in terms], 1) else: ngcd = reduce(igcd, [t[0] for t in terms if t[1]], 0) dlcm = reduce(ilcm, [t[1] for t in terms if t[1]], 1) if ngcd == dlcm == 1: return S.One, self if not inf: for i, (p, q, term) in enumerate(terms): terms[i] = _keep_coeff(Rational((p//ngcd)*(dlcm//q)), term) else: for i, (p, q, term) in enumerate(terms): if q: terms[i] = _keep_coeff(Rational((p//ngcd)*(dlcm//q)), term) else: terms[i] = _keep_coeff(Rational(p, q), term) # we don't need a complete re-flattening since no new terms will join # so we just use the same sort as is used in Add.flatten. When the # coefficient changes, the ordering of terms may change, e.g. # (3*x, 6*y) -> (2*y, x) # # We do need to make sure that term[0] stays in position 0, however. # if terms[0].is_Number or terms[0] is S.ComplexInfinity: c = terms.pop(0) else: c = None _addsort(terms) if c: terms.insert(0, c) return Rational(ngcd, dlcm), self._new_rawargs(*terms) def as_content_primitive(self, radical=False, clear=True): """Return the tuple (R, self/R) where R is the positive Rational extracted from self. If radical is True (default is False) then common radicals will be removed and included as a factor of the primitive expression. Examples ======== >>> from sympy import sqrt >>> (3 + 3*sqrt(2)).as_content_primitive() (3, 1 + sqrt(2)) Radical content can also be factored out of the primitive: >>> (2*sqrt(2) + 4*sqrt(10)).as_content_primitive(radical=True) (2, sqrt(2)*(1 + 2*sqrt(5))) See docstring of Expr.as_content_primitive for more examples. """ con, prim = self.func(*[_keep_coeff(*a.as_content_primitive( radical=radical, clear=clear)) for a in self.args]).primitive() if not clear and not con.is_Integer and prim.is_Add: con, d = con.as_numer_denom() _p = prim/d if any(a.as_coeff_Mul()[0].is_Integer for a in _p.args): prim = _p else: con /= d if radical and prim.is_Add: # look for common radicals that can be removed args = prim.args rads = [] common_q = None for m in args: term_rads = defaultdict(list) for ai in Mul.make_args(m): if ai.is_Pow: b, e = ai.as_base_exp() if e.is_Rational and b.is_Integer: term_rads[e.q].append(abs(int(b))**e.p) if not term_rads: break if common_q is None: common_q = set(term_rads.keys()) else: common_q = common_q & set(term_rads.keys()) if not common_q: break rads.append(term_rads) else: # process rads # keep only those in common_q for r in rads: for q in list(r.keys()): if q not in common_q: r.pop(q) for q in r: r[q] = prod(r[q]) # find the gcd of bases for each q G = [] for q in common_q: g = reduce(igcd, [r[q] for r in rads], 0) if g != 1: G.append(g**Rational(1, q)) if G: G = Mul(*G) args = [ai/G for ai in args] prim = G*prim.func(*args) return con, prim @property def _sorted_args(self): from sympy.core.compatibility import default_sort_key return tuple(sorted(self.args, key=default_sort_key)) def _eval_difference_delta(self, n, step): from sympy.series.limitseq import difference_delta as dd return self.func(*[dd(a, n, step) for a in self.args]) @property def _mpc_(self): """ Convert self to an mpmath mpc if possible """ from sympy.core.numbers import I, Float re_part, rest = self.as_coeff_Add() im_part, imag_unit = rest.as_coeff_Mul() if not imag_unit == I: # ValueError may seem more reasonable but since it's a @property, # we need to use AttributeError to keep from confusing things like # hasattr. raise AttributeError("Cannot convert Add to mpc. Must be of the form Number + Number*I") return (Float(re_part)._mpf_, Float(im_part)._mpf_) from .mul import Mul, _keep_coeff, prod from sympy.core.numbers import Rational

349d0dedff271cc6c7a1c2bffc2fe715eec4f766ac5481eeaaad290b8c275cdd

from __future__ import print_function, division from .sympify import sympify, _sympify, SympifyError from .basic import Basic, Atom from .singleton import S from .evalf import EvalfMixin, pure_complex from .decorators import _sympifyit, call_highest_priority from .cache import cacheit from .compatibility import reduce, as_int, default_sort_key, range, Iterable from mpmath.libmp import mpf_log, prec_to_dps from collections import defaultdict class Expr(Basic, EvalfMixin): """ Base class for algebraic expressions. Everything that requires arithmetic operations to be defined should subclass this class, instead of Basic (which should be used only for argument storage and expression manipulation, i.e. pattern matching, substitutions, etc). See Also ======== sympy.core.basic.Basic """ __slots__ = [] is_scalar = True # self derivative is 1 @property def _diff_wrt(self): """Return True if one can differentiate with respect to this object, else False. Subclasses such as Symbol, Function and Derivative return True to enable derivatives wrt them. The implementation in Derivative separates the Symbol and non-Symbol (_diff_wrt=True) variables and temporarily converts the non-Symbols into Symbols when performing the differentiation. By default, any object deriving from Expr will behave like a scalar with self.diff(self) == 1. If this is not desired then the object must also set `is_scalar = False` or else define an _eval_derivative routine. Note, see the docstring of Derivative for how this should work mathematically. In particular, note that expr.subs(yourclass, Symbol) should be well-defined on a structural level, or this will lead to inconsistent results. Examples ======== >>> from sympy import Expr >>> e = Expr() >>> e._diff_wrt False >>> class MyScalar(Expr): ... _diff_wrt = True ... >>> MyScalar().diff(MyScalar()) 1 >>> class MySymbol(Expr): ... _diff_wrt = True ... is_scalar = False ... >>> MySymbol().diff(MySymbol()) Derivative(MySymbol(), MySymbol()) """ return False @cacheit def sort_key(self, order=None): coeff, expr = self.as_coeff_Mul() if expr.is_Pow: expr, exp = expr.args else: expr, exp = expr, S.One if expr.is_Dummy: args = (expr.sort_key(),) elif expr.is_Atom: args = (str(expr),) else: if expr.is_Add: args = expr.as_ordered_terms(order=order) elif expr.is_Mul: args = expr.as_ordered_factors(order=order) else: args = expr.args args = tuple( [ default_sort_key(arg, order=order) for arg in args ]) args = (len(args), tuple(args)) exp = exp.sort_key(order=order) return expr.class_key(), args, exp, coeff # *************** # * Arithmetics * # *************** # Expr and its sublcasses use _op_priority to determine which object # passed to a binary special method (__mul__, etc.) will handle the # operation. In general, the 'call_highest_priority' decorator will choose # the object with the highest _op_priority to handle the call. # Custom subclasses that want to define their own binary special methods # should set an _op_priority value that is higher than the default. # # **NOTE**: # This is a temporary fix, and will eventually be replaced with # something better and more powerful. See issue 5510. _op_priority = 10.0 def __pos__(self): return self def __neg__(self): return Mul(S.NegativeOne, self) def __abs__(self): from sympy import Abs return Abs(self) @_sympifyit('other', NotImplemented) @call_highest_priority('__radd__') def __add__(self, other): return Add(self, other) @_sympifyit('other', NotImplemented) @call_highest_priority('__add__') def __radd__(self, other): return Add(other, self) @_sympifyit('other', NotImplemented) @call_highest_priority('__rsub__') def __sub__(self, other): return Add(self, -other) @_sympifyit('other', NotImplemented) @call_highest_priority('__sub__') def __rsub__(self, other): return Add(other, -self) @_sympifyit('other', NotImplemented) @call_highest_priority('__rmul__') def __mul__(self, other): return Mul(self, other) @_sympifyit('other', NotImplemented) @call_highest_priority('__mul__') def __rmul__(self, other): return Mul(other, self) @_sympifyit('other', NotImplemented) @call_highest_priority('__rpow__') def _pow(self, other): return Pow(self, other) def __pow__(self, other, mod=None): if mod is None: return self._pow(other) try: _self, other, mod = as_int(self), as_int(other), as_int(mod) if other >= 0: return pow(_self, other, mod) else: from sympy.core.numbers import mod_inverse return mod_inverse(pow(_self, -other, mod), mod) except ValueError: power = self._pow(other) try: return power%mod except TypeError: return NotImplemented @_sympifyit('other', NotImplemented) @call_highest_priority('__pow__') def __rpow__(self, other): return Pow(other, self) @_sympifyit('other', NotImplemented) @call_highest_priority('__rdiv__') def __div__(self, other): return Mul(self, Pow(other, S.NegativeOne)) @_sympifyit('other', NotImplemented) @call_highest_priority('__div__') def __rdiv__(self, other): return Mul(other, Pow(self, S.NegativeOne)) __truediv__ = __div__ __rtruediv__ = __rdiv__ @_sympifyit('other', NotImplemented) @call_highest_priority('__rmod__') def __mod__(self, other): return Mod(self, other) @_sympifyit('other', NotImplemented) @call_highest_priority('__mod__') def __rmod__(self, other): return Mod(other, self) @_sympifyit('other', NotImplemented) @call_highest_priority('__rfloordiv__') def __floordiv__(self, other): from sympy.functions.elementary.integers import floor return floor(self / other) @_sympifyit('other', NotImplemented) @call_highest_priority('__floordiv__') def __rfloordiv__(self, other): from sympy.functions.elementary.integers import floor return floor(other / self) @_sympifyit('other', NotImplemented) @call_highest_priority('__rdivmod__') def __divmod__(self, other): from sympy.functions.elementary.integers import floor return floor(self / other), Mod(self, other) @_sympifyit('other', NotImplemented) @call_highest_priority('__divmod__') def __rdivmod__(self, other): from sympy.functions.elementary.integers import floor return floor(other / self), Mod(other, self) def __int__(self): # Although we only need to round to the units position, we'll # get one more digit so the extra testing below can be avoided # unless the rounded value rounded to an integer, e.g. if an # expression were equal to 1.9 and we rounded to the unit position # we would get a 2 and would not know if this rounded up or not # without doing a test (as done below). But if we keep an extra # digit we know that 1.9 is not the same as 1 and there is no # need for further testing: our int value is correct. If the value # were 1.99, however, this would round to 2.0 and our int value is # off by one. So...if our round value is the same as the int value # (regardless of how much extra work we do to calculate extra decimal # places) we need to test whether we are off by one. from sympy import Dummy if not self.is_number: raise TypeError("can't convert symbols to int") r = self.round(2) if not r.is_Number: raise TypeError("can't convert complex to int") if r in (S.NaN, S.Infinity, S.NegativeInfinity): raise TypeError("can't convert %s to int" % r) i = int(r) if not i: return 0 # off-by-one check if i == r and not (self - i).equals(0): isign = 1 if i > 0 else -1 x = Dummy() # in the following (self - i).evalf(2) will not always work while # (self - r).evalf(2) and the use of subs does; if the test that # was added when this comment was added passes, it might be safe # to simply use sign to compute this rather than doing this by hand: diff_sign = 1 if (self - x).evalf(2, subs={x: i}) > 0 else -1 if diff_sign != isign: i -= isign return i __long__ = __int__ def __float__(self): # Don't bother testing if it's a number; if it's not this is going # to fail, and if it is we still need to check that it evalf'ed to # a number. result = self.evalf() if result.is_Number: return float(result) if result.is_number and result.as_real_imag()[1]: raise TypeError("can't convert complex to float") raise TypeError("can't convert expression to float") def __complex__(self): result = self.evalf() re, im = result.as_real_imag() return complex(float(re), float(im)) def __ge__(self, other): from sympy import GreaterThan try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s >= %s" % (self, other)) for me in (self, other): if me.is_complex and me.is_real is False: raise TypeError("Invalid comparison of complex %s" % me) if me is S.NaN: raise TypeError("Invalid NaN comparison") n2 = _n2(self, other) if n2 is not None: return _sympify(n2 >= 0) if self.is_real or other.is_real: dif = self - other if dif.is_nonnegative is not None and \ dif.is_nonnegative is not dif.is_negative: return sympify(dif.is_nonnegative) return GreaterThan(self, other, evaluate=False) def __le__(self, other): from sympy import LessThan try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s <= %s" % (self, other)) for me in (self, other): if me.is_complex and me.is_real is False: raise TypeError("Invalid comparison of complex %s" % me) if me is S.NaN: raise TypeError("Invalid NaN comparison") n2 = _n2(self, other) if n2 is not None: return _sympify(n2 <= 0) if self.is_real or other.is_real: dif = self - other if dif.is_nonpositive is not None and \ dif.is_nonpositive is not dif.is_positive: return sympify(dif.is_nonpositive) return LessThan(self, other, evaluate=False) def __gt__(self, other): from sympy import StrictGreaterThan try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s > %s" % (self, other)) for me in (self, other): if me.is_complex and me.is_real is False: raise TypeError("Invalid comparison of complex %s" % me) if me is S.NaN: raise TypeError("Invalid NaN comparison") n2 = _n2(self, other) if n2 is not None: return _sympify(n2 > 0) if self.is_real or other.is_real: dif = self - other if dif.is_positive is not None and \ dif.is_positive is not dif.is_nonpositive: return sympify(dif.is_positive) return StrictGreaterThan(self, other, evaluate=False) def __lt__(self, other): from sympy import StrictLessThan try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s < %s" % (self, other)) for me in (self, other): if me.is_complex and me.is_real is False: raise TypeError("Invalid comparison of complex %s" % me) if me is S.NaN: raise TypeError("Invalid NaN comparison") n2 = _n2(self, other) if n2 is not None: return _sympify(n2 < 0) if self.is_real or other.is_real: dif = self - other if dif.is_negative is not None and \ dif.is_negative is not dif.is_nonnegative: return sympify(dif.is_negative) return StrictLessThan(self, other, evaluate=False) def __trunc__(self): if not self.is_number: raise TypeError("can't truncate symbols and expressions") else: return Integer(self) @staticmethod def _from_mpmath(x, prec): from sympy import Float if hasattr(x, "_mpf_"): return Float._new(x._mpf_, prec) elif hasattr(x, "_mpc_"): re, im = x._mpc_ re = Float._new(re, prec) im = Float._new(im, prec)*S.ImaginaryUnit return re + im else: raise TypeError("expected mpmath number (mpf or mpc)") @property def is_number(self): """Returns True if ``self`` has no free symbols and no undefined functions (AppliedUndef, to be precise). It will be faster than ``if not self.free_symbols``, however, since ``is_number`` will fail as soon as it hits a free symbol or undefined function. Examples ======== >>> from sympy import log, Integral, cos, sin, pi >>> from sympy.core.function import Function >>> from sympy.abc import x >>> f = Function('f') >>> x.is_number False >>> f(1).is_number False >>> (2*x).is_number False >>> (2 + Integral(2, x)).is_number False >>> (2 + Integral(2, (x, 1, 2))).is_number True Not all numbers are Numbers in the SymPy sense: >>> pi.is_number, pi.is_Number (True, False) If something is a number it should evaluate to a number with real and imaginary parts that are Numbers; the result may not be comparable, however, since the real and/or imaginary part of the result may not have precision. >>> cos(1).is_number and cos(1).is_comparable True >>> z = cos(1)**2 + sin(1)**2 - 1 >>> z.is_number True >>> z.is_comparable False See Also ======== sympy.core.basic.is_comparable """ return all(obj.is_number for obj in self.args) def _random(self, n=None, re_min=-1, im_min=-1, re_max=1, im_max=1): """Return self evaluated, if possible, replacing free symbols with random complex values, if necessary. The random complex value for each free symbol is generated by the random_complex_number routine giving real and imaginary parts in the range given by the re_min, re_max, im_min, and im_max values. The returned value is evaluated to a precision of n (if given) else the maximum of 15 and the precision needed to get more than 1 digit of precision. If the expression could not be evaluated to a number, or could not be evaluated to more than 1 digit of precision, then None is returned. Examples ======== >>> from sympy import sqrt >>> from sympy.abc import x, y >>> x._random() # doctest: +SKIP 0.0392918155679172 + 0.916050214307199*I >>> x._random(2) # doctest: +SKIP -0.77 - 0.87*I >>> (x + y/2)._random(2) # doctest: +SKIP -0.57 + 0.16*I >>> sqrt(2)._random(2) 1.4 See Also ======== sympy.utilities.randtest.random_complex_number """ free = self.free_symbols prec = 1 if free: from sympy.utilities.randtest import random_complex_number a, c, b, d = re_min, re_max, im_min, im_max reps = dict(list(zip(free, [random_complex_number(a, b, c, d, rational=True) for zi in free]))) try: nmag = abs(self.evalf(2, subs=reps)) except (ValueError, TypeError): # if an out of range value resulted in evalf problems # then return None -- XXX is there a way to know how to # select a good random number for a given expression? # e.g. when calculating n! negative values for n should not # be used return None else: reps = {} nmag = abs(self.evalf(2)) if not hasattr(nmag, '_prec'): # e.g. exp_polar(2*I*pi) doesn't evaluate but is_number is True return None if nmag._prec == 1: # increase the precision up to the default maximum # precision to see if we can get any significance from mpmath.libmp.libintmath import giant_steps from sympy.core.evalf import DEFAULT_MAXPREC as target # evaluate for prec in giant_steps(2, target): nmag = abs(self.evalf(prec, subs=reps)) if nmag._prec != 1: break if nmag._prec != 1: if n is None: n = max(prec, 15) return self.evalf(n, subs=reps) # never got any significance return None def is_constant(self, *wrt, **flags): """Return True if self is constant, False if not, or None if the constancy could not be determined conclusively. If an expression has no free symbols then it is a constant. If there are free symbols it is possible that the expression is a constant, perhaps (but not necessarily) zero. To test such expressions, two strategies are tried: 1) numerical evaluation at two random points. If two such evaluations give two different values and the values have a precision greater than 1 then self is not constant. If the evaluations agree or could not be obtained with any precision, no decision is made. The numerical testing is done only if ``wrt`` is different than the free symbols. 2) differentiation with respect to variables in 'wrt' (or all free symbols if omitted) to see if the expression is constant or not. This will not always lead to an expression that is zero even though an expression is constant (see added test in test_expr.py). If all derivatives are zero then self is constant with respect to the given symbols. If neither evaluation nor differentiation can prove the expression is constant, None is returned unless two numerical values happened to be the same and the flag ``failing_number`` is True -- in that case the numerical value will be returned. If flag simplify=False is passed, self will not be simplified; the default is True since self should be simplified before testing. Examples ======== >>> from sympy import cos, sin, Sum, S, pi >>> from sympy.abc import a, n, x, y >>> x.is_constant() False >>> S(2).is_constant() True >>> Sum(x, (x, 1, 10)).is_constant() True >>> Sum(x, (x, 1, n)).is_constant() False >>> Sum(x, (x, 1, n)).is_constant(y) True >>> Sum(x, (x, 1, n)).is_constant(n) False >>> Sum(x, (x, 1, n)).is_constant(x) True >>> eq = a*cos(x)**2 + a*sin(x)**2 - a >>> eq.is_constant() True >>> eq.subs({x: pi, a: 2}) == eq.subs({x: pi, a: 3}) == 0 True >>> (0**x).is_constant() False >>> x.is_constant() False >>> (x**x).is_constant() False >>> one = cos(x)**2 + sin(x)**2 >>> one.is_constant() True >>> ((one - 1)**(x + 1)).is_constant() in (True, False) # could be 0 or 1 True """ simplify = flags.get('simplify', True) if self.is_number: return True free = self.free_symbols if not free: return True # assume f(1) is some constant # if we are only interested in some symbols and they are not in the # free symbols then this expression is constant wrt those symbols wrt = set(wrt) if wrt and not wrt & free: return True wrt = wrt or free # simplify unless this has already been done expr = self if simplify: expr = expr.simplify() # is_zero should be a quick assumptions check; it can be wrong for # numbers (see test_is_not_constant test), giving False when it # shouldn't, but hopefully it will never give True unless it is sure. if expr.is_zero: return True # try numerical evaluation to see if we get two different values failing_number = None if wrt == free: # try 0 (for a) and 1 (for b) try: a = expr.subs(list(zip(free, [0]*len(free))), simultaneous=True) if a is S.NaN: # evaluation may succeed when substitution fails a = expr._random(None, 0, 0, 0, 0) except ZeroDivisionError: a = None if a is not None and a is not S.NaN: try: b = expr.subs(list(zip(free, [1]*len(free))), simultaneous=True) if b is S.NaN: # evaluation may succeed when substitution fails b = expr._random(None, 1, 0, 1, 0) except ZeroDivisionError: b = None if b is not None and b is not S.NaN and b.equals(a) is False: return False # try random real b = expr._random(None, -1, 0, 1, 0) if b is not None and b is not S.NaN and b.equals(a) is False: return False # try random complex b = expr._random() if b is not None and b is not S.NaN: if b.equals(a) is False: return False failing_number = a if a.is_number else b # now we will test each wrt symbol (or all free symbols) to see if the # expression depends on them or not using differentiation. This is # not sufficient for all expressions, however, so we don't return # False if we get a derivative other than 0 with free symbols. for w in wrt: deriv = expr.diff(w) if simplify: deriv = deriv.simplify() if deriv != 0: if not (pure_complex(deriv, or_real=True)): if flags.get('failing_number', False): return failing_number elif deriv.free_symbols: # dead line provided _random returns None in such cases return None return False return True def equals(self, other, failing_expression=False): """Return True if self == other, False if it doesn't, or None. If failing_expression is True then the expression which did not simplify to a 0 will be returned instead of None. If ``self`` is a Number (or complex number) that is not zero, then the result is False. If ``self`` is a number and has not evaluated to zero, evalf will be used to test whether the expression evaluates to zero. If it does so and the result has significance (i.e. the precision is either -1, for a Rational result, or is greater than 1) then the evalf value will be used to return True or False. """ from sympy.simplify.simplify import nsimplify, simplify from sympy.solvers.solveset import solveset from sympy.polys.polyerrors import NotAlgebraic from sympy.polys.numberfields import minimal_polynomial other = sympify(other) if self == other: return True # they aren't the same so see if we can make the difference 0; # don't worry about doing simplification steps one at a time # because if the expression ever goes to 0 then the subsequent # simplification steps that are done will be very fast. diff = factor_terms(simplify(self - other), radical=True) if not diff: return True if not diff.has(Add, Mod): # if there is no expanding to be done after simplifying # then this can't be a zero return False constant = diff.is_constant(simplify=False, failing_number=True) if constant is False: return False if constant is None and (diff.free_symbols or not diff.is_number): # e.g. unless the right simplification is done, a symbolic # zero is possible (see expression of issue 6829: without # simplification constant will be None). return if constant is True: ndiff = diff._random() if ndiff: return False # sometimes we can use a simplified result to give a clue as to # what the expression should be; if the expression is *not* zero # then we should have been able to compute that and so now # we can just consider the cases where the approximation appears # to be zero -- we try to prove it via minimal_polynomial. if diff.is_number: approx = diff.nsimplify() if not approx: # try to prove via self-consistency surds = [s for s in diff.atoms(Pow) if s.args[0].is_Integer] # it seems to work better to try big ones first surds.sort(key=lambda x: -x.args[0]) for s in surds: try: # simplify is False here -- this expression has already # been identified as being hard to identify as zero; # we will handle the checking ourselves using nsimplify # to see if we are in the right ballpark or not and if so # *then* the simplification will be attempted. if s.is_Symbol: sol = list(solveset(diff, s)) else: sol = [s] if sol: if s in sol: return True if s.is_real: if any(nsimplify(si, [s]) == s and simplify(si) == s for si in sol): return True except NotImplementedError: pass # try to prove with minimal_polynomial but know when # *not* to use this or else it can take a long time. e.g. issue 8354 if True: # change True to condition that assures non-hang try: mp = minimal_polynomial(diff) if mp.is_Symbol: return True return False except (NotAlgebraic, NotImplementedError): pass # diff has not simplified to zero; constant is either None, True # or the number with significance (prec != 1) that was randomly # calculated twice as the same value. if constant not in (True, None) and constant != 0: return False if failing_expression: return diff return None def _eval_is_positive(self): from sympy.polys.numberfields import minimal_polynomial from sympy.polys.polyerrors import NotAlgebraic if self.is_number: if self.is_real is False: return False try: # check to see that we can get a value n2 = self._eval_evalf(2) if n2 is None: raise AttributeError if n2._prec == 1: # no significance raise AttributeError if n2 == S.NaN: raise AttributeError except (AttributeError, ValueError): return None n, i = self.evalf(2).as_real_imag() if not i.is_Number or not n.is_Number: return False if n._prec != 1 and i._prec != 1: return bool(not i and n > 0) elif n._prec == 1 and (not i or i._prec == 1) and \ self.is_algebraic and not self.has(Function): try: if minimal_polynomial(self).is_Symbol: return False except (NotAlgebraic, NotImplementedError): pass def _eval_is_negative(self): from sympy.polys.numberfields import minimal_polynomial from sympy.polys.polyerrors import NotAlgebraic if self.is_number: if self.is_real is False: return False try: # check to see that we can get a value n2 = self._eval_evalf(2) if n2 is None: raise AttributeError if n2._prec == 1: # no significance raise AttributeError if n2 == S.NaN: raise AttributeError except (AttributeError, ValueError): return None n, i = self.evalf(2).as_real_imag() if not i.is_Number or not n.is_Number: return False if n._prec != 1 and i._prec != 1: return bool(not i and n < 0) elif n._prec == 1 and (not i or i._prec == 1) and \ self.is_algebraic and not self.has(Function): try: if minimal_polynomial(self).is_Symbol: return False except (NotAlgebraic, NotImplementedError): pass def _eval_interval(self, x, a, b): """ Returns evaluation over an interval. For most functions this is: self.subs(x, b) - self.subs(x, a), possibly using limit() if NaN is returned from subs, or if singularities are found between a and b. If b or a is None, it only evaluates -self.subs(x, a) or self.subs(b, x), respectively. """ from sympy.series import limit, Limit from sympy.solvers.solveset import solveset from sympy.sets.sets import Interval from sympy.functions.elementary.exponential import log from sympy.calculus.util import AccumBounds if (a is None and b is None): raise ValueError('Both interval ends cannot be None.') if a == b: return 0 if a is None: A = 0 else: A = self.subs(x, a) if A.has(S.NaN, S.Infinity, S.NegativeInfinity, S.ComplexInfinity, AccumBounds): if (a < b) != False: A = limit(self, x, a,"+") else: A = limit(self, x, a,"-") if A is S.NaN: return A if isinstance(A, Limit): raise NotImplementedError("Could not compute limit") if b is None: B = 0 else: B = self.subs(x, b) if B.has(S.NaN, S.Infinity, S.NegativeInfinity, S.ComplexInfinity, AccumBounds): if (a < b) != False: B = limit(self, x, b,"-") else: B = limit(self, x, b,"+") if isinstance(B, Limit): raise NotImplementedError("Could not compute limit") if (a and b) is None: return B - A value = B - A if a.is_comparable and b.is_comparable: if a < b: domain = Interval(a, b) else: domain = Interval(b, a) # check the singularities of self within the interval # if singularities is a ConditionSet (not iterable), catch the exception and pass singularities = solveset(self.cancel().as_numer_denom()[1], x, domain=domain) for logterm in self.atoms(log): singularities = singularities | solveset(logterm.args[0], x, domain=domain) try: for s in singularities: if value is S.NaN: # no need to keep adding, it will stay NaN break if not s.is_comparable: continue if (a < s) == (s < b) == True: value += -limit(self, x, s, "+") + limit(self, x, s, "-") elif (b < s) == (s < a) == True: value += limit(self, x, s, "+") - limit(self, x, s, "-") except TypeError: pass return value def _eval_power(self, other): # subclass to compute self**other for cases when # other is not NaN, 0, or 1 return None def _eval_conjugate(self): if self.is_real: return self elif self.is_imaginary: return -self def conjugate(self): from sympy.functions.elementary.complexes import conjugate as c return c(self) def _eval_transpose(self): from sympy.functions.elementary.complexes import conjugate if self.is_complex: return self elif self.is_hermitian: return conjugate(self) elif self.is_antihermitian: return -conjugate(self) def transpose(self): from sympy.functions.elementary.complexes import transpose return transpose(self) def _eval_adjoint(self): from sympy.functions.elementary.complexes import conjugate, transpose if self.is_hermitian: return self elif self.is_antihermitian: return -self obj = self._eval_conjugate() if obj is not None: return transpose(obj) obj = self._eval_transpose() if obj is not None: return conjugate(obj) def adjoint(self): from sympy.functions.elementary.complexes import adjoint return adjoint(self) @classmethod def _parse_order(cls, order): """Parse and configure the ordering of terms. """ from sympy.polys.orderings import monomial_key try: reverse = order.startswith('rev-') except AttributeError: reverse = False else: if reverse: order = order[4:] monom_key = monomial_key(order) def neg(monom): result = [] for m in monom: if isinstance(m, tuple): result.append(neg(m)) else: result.append(-m) return tuple(result) def key(term): _, ((re, im), monom, ncpart) = term monom = neg(monom_key(monom)) ncpart = tuple([e.sort_key(order=order) for e in ncpart]) coeff = ((bool(im), im), (re, im)) return monom, ncpart, coeff return key, reverse def as_ordered_factors(self, order=None): """Return list of ordered factors (if Mul) else [self].""" return [self] def as_ordered_terms(self, order=None, data=False): """ Transform an expression to an ordered list of terms. Examples ======== >>> from sympy import sin, cos >>> from sympy.abc import x >>> (sin(x)**2*cos(x) + sin(x)**2 + 1).as_ordered_terms() [sin(x)**2*cos(x), sin(x)**2, 1] """ key, reverse = self._parse_order(order) terms, gens = self.as_terms() if not any(term.is_Order for term, _ in terms): ordered = sorted(terms, key=key, reverse=reverse) else: _terms, _order = [], [] for term, repr in terms: if not term.is_Order: _terms.append((term, repr)) else: _order.append((term, repr)) ordered = sorted(_terms, key=key, reverse=True) \ + sorted(_order, key=key, reverse=True) if data: return ordered, gens else: return [term for term, _ in ordered] def as_terms(self): """Transform an expression to a list of terms. """ from .add import Add from .mul import Mul from .exprtools import decompose_power gens, terms = set([]), [] for term in Add.make_args(self): coeff, _term = term.as_coeff_Mul() coeff = complex(coeff) cpart, ncpart = {}, [] if _term is not S.One: for factor in Mul.make_args(_term): if factor.is_number: try: coeff *= complex(factor) except (TypeError, ValueError): pass else: continue if factor.is_commutative: base, exp = decompose_power(factor) cpart[base] = exp gens.add(base) else: ncpart.append(factor) coeff = coeff.real, coeff.imag ncpart = tuple(ncpart) terms.append((term, (coeff, cpart, ncpart))) gens = sorted(gens, key=default_sort_key) k, indices = len(gens), {} for i, g in enumerate(gens): indices[g] = i result = [] for term, (coeff, cpart, ncpart) in terms: monom = [0]*k for base, exp in cpart.items(): monom[indices[base]] = exp result.append((term, (coeff, tuple(monom), ncpart))) return result, gens def removeO(self): """Removes the additive O(..) symbol if there is one""" return self def getO(self): """Returns the additive O(..) symbol if there is one, else None.""" return None def getn(self): """ Returns the order of the expression. The order is determined either from the O(...) term. If there is no O(...) term, it returns None. Examples ======== >>> from sympy import O >>> from sympy.abc import x >>> (1 + x + O(x**2)).getn() 2 >>> (1 + x).getn() """ from sympy import Dummy, Symbol o = self.getO() if o is None: return None elif o.is_Order: o = o.expr if o is S.One: return S.Zero if o.is_Symbol: return S.One if o.is_Pow: return o.args[1] if o.is_Mul: # x**n*log(x)**n or x**n/log(x)**n for oi in o.args: if oi.is_Symbol: return S.One if oi.is_Pow: syms = oi.atoms(Symbol) if len(syms) == 1: x = syms.pop() oi = oi.subs(x, Dummy('x', positive=True)) if oi.base.is_Symbol and oi.exp.is_Rational: return abs(oi.exp) raise NotImplementedError('not sure of order of %s' % o) def count_ops(self, visual=None): """wrapper for count_ops that returns the operation count.""" from .function import count_ops return count_ops(self, visual) def args_cnc(self, cset=False, warn=True, split_1=True): """Return [commutative factors, non-commutative factors] of self. self is treated as a Mul and the ordering of the factors is maintained. If ``cset`` is True the commutative factors will be returned in a set. If there were repeated factors (as may happen with an unevaluated Mul) then an error will be raised unless it is explicitly suppressed by setting ``warn`` to False. Note: -1 is always separated from a Number unless split_1 is False. >>> from sympy import symbols, oo >>> A, B = symbols('A B', commutative=0) >>> x, y = symbols('x y') >>> (-2*x*y).args_cnc() [[-1, 2, x, y], []] >>> (-2.5*x).args_cnc() [[-1, 2.5, x], []] >>> (-2*x*A*B*y).args_cnc() [[-1, 2, x, y], [A, B]] >>> (-2*x*A*B*y).args_cnc(split_1=False) [[-2, x, y], [A, B]] >>> (-2*x*y).args_cnc(cset=True) [{-1, 2, x, y}, []] The arg is always treated as a Mul: >>> (-2 + x + A).args_cnc() [[], [x - 2 + A]] >>> (-oo).args_cnc() # -oo is a singleton [[-1, oo], []] """ if self.is_Mul: args = list(self.args) else: args = [self] for i, mi in enumerate(args): if not mi.is_commutative: c = args[:i] nc = args[i:] break else: c = args nc = [] if c and split_1 and ( c[0].is_Number and c[0].is_negative and c[0] is not S.NegativeOne): c[:1] = [S.NegativeOne, -c[0]] if cset: clen = len(c) c = set(c) if clen and warn and len(c) != clen: raise ValueError('repeated commutative arguments: %s' % [ci for ci in c if list(self.args).count(ci) > 1]) return [c, nc] def coeff(self, x, n=1, right=False): """ Returns the coefficient from the term(s) containing ``x**n``. If ``n`` is zero then all terms independent of ``x`` will be returned. When ``x`` is noncommutative, the coefficient to the left (default) or right of ``x`` can be returned. The keyword 'right' is ignored when ``x`` is commutative. See Also ======== as_coefficient: separate the expression into a coefficient and factor as_coeff_Add: separate the additive constant from an expression as_coeff_Mul: separate the multiplicative constant from an expression as_independent: separate x-dependent terms/factors from others sympy.polys.polytools.coeff_monomial: efficiently find the single coefficient of a monomial in Poly sympy.polys.polytools.nth: like coeff_monomial but powers of monomial terms are used Examples ======== >>> from sympy import symbols >>> from sympy.abc import x, y, z You can select terms that have an explicit negative in front of them: >>> (-x + 2*y).coeff(-1) x >>> (x - 2*y).coeff(-1) 2*y You can select terms with no Rational coefficient: >>> (x + 2*y).coeff(1) x >>> (3 + 2*x + 4*x**2).coeff(1) 0 You can select terms independent of x by making n=0; in this case expr.as_independent(x)[0] is returned (and 0 will be returned instead of None): >>> (3 + 2*x + 4*x**2).coeff(x, 0) 3 >>> eq = ((x + 1)**3).expand() + 1 >>> eq x**3 + 3*x**2 + 3*x + 2 >>> [eq.coeff(x, i) for i in reversed(range(4))] [1, 3, 3, 2] >>> eq -= 2 >>> [eq.coeff(x, i) for i in reversed(range(4))] [1, 3, 3, 0] You can select terms that have a numerical term in front of them: >>> (-x - 2*y).coeff(2) -y >>> from sympy import sqrt >>> (x + sqrt(2)*x).coeff(sqrt(2)) x The matching is exact: >>> (3 + 2*x + 4*x**2).coeff(x) 2 >>> (3 + 2*x + 4*x**2).coeff(x**2) 4 >>> (3 + 2*x + 4*x**2).coeff(x**3) 0 >>> (z*(x + y)**2).coeff((x + y)**2) z >>> (z*(x + y)**2).coeff(x + y) 0 In addition, no factoring is done, so 1 + z*(1 + y) is not obtained from the following: >>> (x + z*(x + x*y)).coeff(x) 1 If such factoring is desired, factor_terms can be used first: >>> from sympy import factor_terms >>> factor_terms(x + z*(x + x*y)).coeff(x) z*(y + 1) + 1 >>> n, m, o = symbols('n m o', commutative=False) >>> n.coeff(n) 1 >>> (3*n).coeff(n) 3 >>> (n*m + m*n*m).coeff(n) # = (1 + m)*n*m 1 + m >>> (n*m + m*n*m).coeff(n, right=True) # = (1 + m)*n*m m If there is more than one possible coefficient 0 is returned: >>> (n*m + m*n).coeff(n) 0 If there is only one possible coefficient, it is returned: >>> (n*m + x*m*n).coeff(m*n) x >>> (n*m + x*m*n).coeff(m*n, right=1) 1 """ x = sympify(x) if not isinstance(x, Basic): return S.Zero n = as_int(n) if not x: return S.Zero if x == self: if n == 1: return S.One return S.Zero if x is S.One: co = [a for a in Add.make_args(self) if a.as_coeff_Mul()[0] is S.One] if not co: return S.Zero return Add(*co) if n == 0: if x.is_Add and self.is_Add: c = self.coeff(x, right=right) if not c: return S.Zero if not right: return self - Add(*[a*x for a in Add.make_args(c)]) return self - Add(*[x*a for a in Add.make_args(c)]) return self.as_independent(x, as_Add=True)[0] # continue with the full method, looking for this power of x: x = x**n def incommon(l1, l2): if not l1 or not l2: return [] n = min(len(l1), len(l2)) for i in range(n): if l1[i] != l2[i]: return l1[:i] return l1[:] def find(l, sub, first=True): """ Find where list sub appears in list l. When ``first`` is True the first occurrence from the left is returned, else the last occurrence is returned. Return None if sub is not in l. >> l = range(5)*2 >> find(l, [2, 3]) 2 >> find(l, [2, 3], first=0) 7 >> find(l, [2, 4]) None """ if not sub or not l or len(sub) > len(l): return None n = len(sub) if not first: l.reverse() sub.reverse() for i in range(0, len(l) - n + 1): if all(l[i + j] == sub[j] for j in range(n)): break else: i = None if not first: l.reverse() sub.reverse() if i is not None and not first: i = len(l) - (i + n) return i co = [] args = Add.make_args(self) self_c = self.is_commutative x_c = x.is_commutative if self_c and not x_c: return S.Zero if self_c: xargs = x.args_cnc(cset=True, warn=False)[0] for a in args: margs = a.args_cnc(cset=True, warn=False)[0] if len(xargs) > len(margs): continue resid = margs.difference(xargs) if len(resid) + len(xargs) == len(margs): co.append(Mul(*resid)) if co == []: return S.Zero elif co: return Add(*co) elif x_c: xargs = x.args_cnc(cset=True, warn=False)[0] for a in args: margs, nc = a.args_cnc(cset=True) if len(xargs) > len(margs): continue resid = margs.difference(xargs) if len(resid) + len(xargs) == len(margs): co.append(Mul(*(list(resid) + nc))) if co == []: return S.Zero elif co: return Add(*co) else: # both nc xargs, nx = x.args_cnc(cset=True) # find the parts that pass the commutative terms for a in args: margs, nc = a.args_cnc(cset=True) if len(xargs) > len(margs): continue resid = margs.difference(xargs) if len(resid) + len(xargs) == len(margs): co.append((resid, nc)) # now check the non-comm parts if not co: return S.Zero if all(n == co[0][1] for r, n in co): ii = find(co[0][1], nx, right) if ii is not None: if not right: return Mul(Add(*[Mul(*r) for r, c in co]), Mul(*co[0][1][:ii])) else: return Mul(*co[0][1][ii + len(nx):]) beg = reduce(incommon, (n[1] for n in co)) if beg: ii = find(beg, nx, right) if ii is not None: if not right: gcdc = co[0][0] for i in range(1, len(co)): gcdc = gcdc.intersection(co[i][0]) if not gcdc: break return Mul(*(list(gcdc) + beg[:ii])) else: m = ii + len(nx) return Add(*[Mul(*(list(r) + n[m:])) for r, n in co]) end = list(reversed( reduce(incommon, (list(reversed(n[1])) for n in co)))) if end: ii = find(end, nx, right) if ii is not None: if not right: return Add(*[Mul(*(list(r) + n[:-len(end) + ii])) for r, n in co]) else: return Mul(*end[ii + len(nx):]) # look for single match hit = None for i, (r, n) in enumerate(co): ii = find(n, nx, right) if ii is not None: if not hit: hit = ii, r, n else: break else: if hit: ii, r, n = hit if not right: return Mul(*(list(r) + n[:ii])) else: return Mul(*n[ii + len(nx):]) return S.Zero def as_expr(self, *gens): """ Convert a polynomial to a SymPy expression. Examples ======== >>> from sympy import sin >>> from sympy.abc import x, y >>> f = (x**2 + x*y).as_poly(x, y) >>> f.as_expr() x**2 + x*y >>> sin(x).as_expr() sin(x) """ return self def as_coefficient(self, expr): """ Extracts symbolic coefficient at the given expression. In other words, this functions separates 'self' into the product of 'expr' and 'expr'-free coefficient. If such separation is not possible it will return None. Examples ======== >>> from sympy import E, pi, sin, I, Poly >>> from sympy.abc import x >>> E.as_coefficient(E) 1 >>> (2*E).as_coefficient(E) 2 >>> (2*sin(E)*E).as_coefficient(E) Two terms have E in them so a sum is returned. (If one were desiring the coefficient of the term exactly matching E then the constant from the returned expression could be selected. Or, for greater precision, a method of Poly can be used to indicate the desired term from which the coefficient is desired.) >>> (2*E + x*E).as_coefficient(E) x + 2 >>> _.args[0] # just want the exact match 2 >>> p = Poly(2*E + x*E); p Poly(x*E + 2*E, x, E, domain='ZZ') >>> p.coeff_monomial(E) 2 >>> p.nth(0, 1) 2 Since the following cannot be written as a product containing E as a factor, None is returned. (If the coefficient ``2*x`` is desired then the ``coeff`` method should be used.) >>> (2*E*x + x).as_coefficient(E) >>> (2*E*x + x).coeff(E) 2*x >>> (E*(x + 1) + x).as_coefficient(E) >>> (2*pi*I).as_coefficient(pi*I) 2 >>> (2*I).as_coefficient(pi*I) See Also ======== coeff: return sum of terms have a given factor as_coeff_Add: separate the additive constant from an expression as_coeff_Mul: separate the multiplicative constant from an expression as_independent: separate x-dependent terms/factors from others sympy.polys.polytools.coeff_monomial: efficiently find the single coefficient of a monomial in Poly sympy.polys.polytools.nth: like coeff_monomial but powers of monomial terms are used """ r = self.extract_multiplicatively(expr) if r and not r.has(expr): return r def as_independent(self, *deps, **hint): """ A mostly naive separation of a Mul or Add into arguments that are not are dependent on deps. To obtain as complete a separation of variables as possible, use a separation method first, e.g.: * separatevars() to change Mul, Add and Pow (including exp) into Mul * .expand(mul=True) to change Add or Mul into Add * .expand(log=True) to change log expr into an Add The only non-naive thing that is done here is to respect noncommutative ordering of variables and to always return (0, 0) for `self` of zero regardless of hints. For nonzero `self`, the returned tuple (i, d) has the following interpretation: * i will has no variable that appears in deps * d will either have terms that contain variables that are in deps, or be equal to 0 (when self is an Add) or 1 (when self is a Mul) * if self is an Add then self = i + d * if self is a Mul then self = i*d * otherwise (self, S.One) or (S.One, self) is returned. To force the expression to be treated as an Add, use the hint as_Add=True Examples ======== -- self is an Add >>> from sympy import sin, cos, exp >>> from sympy.abc import x, y, z >>> (x + x*y).as_independent(x) (0, x*y + x) >>> (x + x*y).as_independent(y) (x, x*y) >>> (2*x*sin(x) + y + x + z).as_independent(x) (y + z, 2*x*sin(x) + x) >>> (2*x*sin(x) + y + x + z).as_independent(x, y) (z, 2*x*sin(x) + x + y) -- self is a Mul >>> (x*sin(x)*cos(y)).as_independent(x) (cos(y), x*sin(x)) non-commutative terms cannot always be separated out when self is a Mul >>> from sympy import symbols >>> n1, n2, n3 = symbols('n1 n2 n3', commutative=False) >>> (n1 + n1*n2).as_independent(n2) (n1, n1*n2) >>> (n2*n1 + n1*n2).as_independent(n2) (0, n1*n2 + n2*n1) >>> (n1*n2*n3).as_independent(n1) (1, n1*n2*n3) >>> (n1*n2*n3).as_independent(n2) (n1, n2*n3) >>> ((x-n1)*(x-y)).as_independent(x) (1, (x - y)*(x - n1)) -- self is anything else: >>> (sin(x)).as_independent(x) (1, sin(x)) >>> (sin(x)).as_independent(y) (sin(x), 1) >>> exp(x+y).as_independent(x) (1, exp(x + y)) -- force self to be treated as an Add: >>> (3*x).as_independent(x, as_Add=True) (0, 3*x) -- force self to be treated as a Mul: >>> (3+x).as_independent(x, as_Add=False) (1, x + 3) >>> (-3+x).as_independent(x, as_Add=False) (1, x - 3) Note how the below differs from the above in making the constant on the dep term positive. >>> (y*(-3+x)).as_independent(x) (y, x - 3) -- use .as_independent() for true independence testing instead of .has(). The former considers only symbols in the free symbols while the latter considers all symbols >>> from sympy import Integral >>> I = Integral(x, (x, 1, 2)) >>> I.has(x) True >>> x in I.free_symbols False >>> I.as_independent(x) == (I, 1) True >>> (I + x).as_independent(x) == (I, x) True Note: when trying to get independent terms, a separation method might need to be used first. In this case, it is important to keep track of what you send to this routine so you know how to interpret the returned values >>> from sympy import separatevars, log >>> separatevars(exp(x+y)).as_independent(x) (exp(y), exp(x)) >>> (x + x*y).as_independent(y) (x, x*y) >>> separatevars(x + x*y).as_independent(y) (x, y + 1) >>> (x*(1 + y)).as_independent(y) (x, y + 1) >>> (x*(1 + y)).expand(mul=True).as_independent(y) (x, x*y) >>> a, b=symbols('a b', positive=True) >>> (log(a*b).expand(log=True)).as_independent(b) (log(a), log(b)) See Also ======== .separatevars(), .expand(log=True), Add.as_two_terms(), Mul.as_two_terms(), .as_coeff_add(), .as_coeff_mul() """ from .symbol import Symbol from .add import _unevaluated_Add from .mul import _unevaluated_Mul from sympy.utilities.iterables import sift if self.is_zero: return S.Zero, S.Zero func = self.func if hint.get('as_Add', isinstance(self, Add) ): want = Add else: want = Mul # sift out deps into symbolic and other and ignore # all symbols but those that are in the free symbols sym = set() other = [] for d in deps: if isinstance(d, Symbol): # Symbol.is_Symbol is True sym.add(d) else: other.append(d) def has(e): """return the standard has() if there are no literal symbols, else check to see that symbol-deps are in the free symbols.""" has_other = e.has(*other) if not sym: return has_other return has_other or e.has(*(e.free_symbols & sym)) if (want is not func or func is not Add and func is not Mul): if has(self): return (want.identity, self) else: return (self, want.identity) else: if func is Add: args = list(self.args) else: args, nc = self.args_cnc() d = sift(args, lambda x: has(x)) depend = d[True] indep = d[False] if func is Add: # all terms were treated as commutative return (Add(*indep), _unevaluated_Add(*depend)) else: # handle noncommutative by stopping at first dependent term for i, n in enumerate(nc): if has(n): depend.extend(nc[i:]) break indep.append(n) return Mul(*indep), ( Mul(*depend, evaluate=False) if nc else _unevaluated_Mul(*depend)) def as_real_imag(self, deep=True, **hints): """Performs complex expansion on 'self' and returns a tuple containing collected both real and imaginary parts. This method can't be confused with re() and im() functions, which does not perform complex expansion at evaluation. However it is possible to expand both re() and im() functions and get exactly the same results as with a single call to this function. >>> from sympy import symbols, I >>> x, y = symbols('x,y', real=True) >>> (x + y*I).as_real_imag() (x, y) >>> from sympy.abc import z, w >>> (z + w*I).as_real_imag() (re(z) - im(w), re(w) + im(z)) """ from sympy import im, re if hints.get('ignore') == self: return None else: return (re(self), im(self)) def as_powers_dict(self): """Return self as a dictionary of factors with each factor being treated as a power. The keys are the bases of the factors and the values, the corresponding exponents. The resulting dictionary should be used with caution if the expression is a Mul and contains non- commutative factors since the order that they appeared will be lost in the dictionary. See Also ======== as_ordered_factors: An alternative for noncommutative applications, returning an ordered list of factors. args_cnc: Similar to as_ordered_factors, but guarantees separation of commutative and noncommutative factors. """ d = defaultdict(int) d.update(dict([self.as_base_exp()])) return d def as_coefficients_dict(self): """Return a dictionary mapping terms to their Rational coefficient. Since the dictionary is a defaultdict, inquiries about terms which were not present will return a coefficient of 0. If an expression is not an Add it is considered to have a single term. Examples ======== >>> from sympy.abc import a, x >>> (3*x + a*x + 4).as_coefficients_dict() {1: 4, x: 3, a*x: 1} >>> _[a] 0 >>> (3*a*x).as_coefficients_dict() {a*x: 3} """ c, m = self.as_coeff_Mul() if not c.is_Rational: c = S.One m = self d = defaultdict(int) d.update({m: c}) return d def as_base_exp(self): # a -> b ** e return self, S.One def as_coeff_mul(self, *deps, **kwargs): """Return the tuple (c, args) where self is written as a Mul, ``m``. c should be a Rational multiplied by any factors of the Mul that are independent of deps. args should be a tuple of all other factors of m; args is empty if self is a Number or if self is independent of deps (when given). This should be used when you don't know if self is a Mul or not but you want to treat self as a Mul or if you want to process the individual arguments of the tail of self as a Mul. - if you know self is a Mul and want only the head, use self.args[0]; - if you don't want to process the arguments of the tail but need the tail then use self.as_two_terms() which gives the head and tail; - if you want to split self into an independent and dependent parts use ``self.as_independent(*deps)`` >>> from sympy import S >>> from sympy.abc import x, y >>> (S(3)).as_coeff_mul() (3, ()) >>> (3*x*y).as_coeff_mul() (3, (x, y)) >>> (3*x*y).as_coeff_mul(x) (3*y, (x,)) >>> (3*y).as_coeff_mul(x) (3*y, ()) """ if deps: if not self.has(*deps): return self, tuple() return S.One, (self,) def as_coeff_add(self, *deps): """Return the tuple (c, args) where self is written as an Add, ``a``. c should be a Rational added to any terms of the Add that are independent of deps. args should be a tuple of all other terms of ``a``; args is empty if self is a Number or if self is independent of deps (when given). This should be used when you don't know if self is an Add or not but you want to treat self as an Add or if you want to process the individual arguments of the tail of self as an Add. - if you know self is an Add and want only the head, use self.args[0]; - if you don't want to process the arguments of the tail but need the tail then use self.as_two_terms() which gives the head and tail. - if you want to split self into an independent and dependent parts use ``self.as_independent(*deps)`` >>> from sympy import S >>> from sympy.abc import x, y >>> (S(3)).as_coeff_add() (3, ()) >>> (3 + x).as_coeff_add() (3, (x,)) >>> (3 + x + y).as_coeff_add(x) (y + 3, (x,)) >>> (3 + y).as_coeff_add(x) (y + 3, ()) """ if deps: if not self.has(*deps): return self, tuple() return S.Zero, (self,) def primitive(self): """Return the positive Rational that can be extracted non-recursively from every term of self (i.e., self is treated like an Add). This is like the as_coeff_Mul() method but primitive always extracts a positive Rational (never a negative or a Float). Examples ======== >>> from sympy.abc import x >>> (3*(x + 1)**2).primitive() (3, (x + 1)**2) >>> a = (6*x + 2); a.primitive() (2, 3*x + 1) >>> b = (x/2 + 3); b.primitive() (1/2, x + 6) >>> (a*b).primitive() == (1, a*b) True """ if not self: return S.One, S.Zero c, r = self.as_coeff_Mul(rational=True) if c.is_negative: c, r = -c, -r return c, r def as_content_primitive(self, radical=False, clear=True): """This method should recursively remove a Rational from all arguments and return that (content) and the new self (primitive). The content should always be positive and ``Mul(*foo.as_content_primitive()) == foo``. The primitive need not be in canonical form and should try to preserve the underlying structure if possible (i.e. expand_mul should not be applied to self). Examples ======== >>> from sympy import sqrt >>> from sympy.abc import x, y, z >>> eq = 2 + 2*x + 2*y*(3 + 3*y) The as_content_primitive function is recursive and retains structure: >>> eq.as_content_primitive() (2, x + 3*y*(y + 1) + 1) Integer powers will have Rationals extracted from the base: >>> ((2 + 6*x)**2).as_content_primitive() (4, (3*x + 1)**2) >>> ((2 + 6*x)**(2*y)).as_content_primitive() (1, (2*(3*x + 1))**(2*y)) Terms may end up joining once their as_content_primitives are added: >>> ((5*(x*(1 + y)) + 2*x*(3 + 3*y))).as_content_primitive() (11, x*(y + 1)) >>> ((3*(x*(1 + y)) + 2*x*(3 + 3*y))).as_content_primitive() (9, x*(y + 1)) >>> ((3*(z*(1 + y)) + 2.0*x*(3 + 3*y))).as_content_primitive() (1, 6.0*x*(y + 1) + 3*z*(y + 1)) >>> ((5*(x*(1 + y)) + 2*x*(3 + 3*y))**2).as_content_primitive() (121, x**2*(y + 1)**2) >>> ((5*(x*(1 + y)) + 2.0*x*(3 + 3*y))**2).as_content_primitive() (1, 121.0*x**2*(y + 1)**2) Radical content can also be factored out of the primitive: >>> (2*sqrt(2) + 4*sqrt(10)).as_content_primitive(radical=True) (2, sqrt(2)*(1 + 2*sqrt(5))) If clear=False (default is True) then content will not be removed from an Add if it can be distributed to leave one or more terms with integer coefficients. >>> (x/2 + y).as_content_primitive() (1/2, x + 2*y) >>> (x/2 + y).as_content_primitive(clear=False) (1, x/2 + y) """ return S.One, self def as_numer_denom(self): """ expression -> a/b -> a, b This is just a stub that should be defined by an object's class methods to get anything else. See Also ======== normal: return a/b instead of a, b """ return self, S.One def normal(self): from .mul import _unevaluated_Mul n, d = self.as_numer_denom() if d is S.One: return n if d.is_Number: return _unevaluated_Mul(n, 1/d) else: return n/d def extract_multiplicatively(self, c): """Return None if it's not possible to make self in the form c * something in a nice way, i.e. preserving the properties of arguments of self. Examples ======== >>> from sympy import symbols, Rational >>> x, y = symbols('x,y', real=True) >>> ((x*y)**3).extract_multiplicatively(x**2 * y) x*y**2 >>> ((x*y)**3).extract_multiplicatively(x**4 * y) >>> (2*x).extract_multiplicatively(2) x >>> (2*x).extract_multiplicatively(3) >>> (Rational(1, 2)*x).extract_multiplicatively(3) x/6 """ c = sympify(c) if self is S.NaN: return None if c is S.One: return self elif c == self: return S.One if c.is_Add: cc, pc = c.primitive() if cc is not S.One: c = Mul(cc, pc, evaluate=False) if c.is_Mul: a, b = c.as_two_terms() x = self.extract_multiplicatively(a) if x is not None: return x.extract_multiplicatively(b) quotient = self / c if self.is_Number: if self is S.Infinity: if c.is_positive: return S.Infinity elif self is S.NegativeInfinity: if c.is_negative: return S.Infinity elif c.is_positive: return S.NegativeInfinity elif self is S.ComplexInfinity: if not c.is_zero: return S.ComplexInfinity elif self.is_Integer: if not quotient.is_Integer: return None elif self.is_positive and quotient.is_negative: return None else: return quotient elif self.is_Rational: if not quotient.is_Rational: return None elif self.is_positive and quotient.is_negative: return None else: return quotient elif self.is_Float: if not quotient.is_Float: return None elif self.is_positive and quotient.is_negative: return None else: return quotient elif self.is_NumberSymbol or self.is_Symbol or self is S.ImaginaryUnit: if quotient.is_Mul and len(quotient.args) == 2: if quotient.args[0].is_Integer and quotient.args[0].is_positive and quotient.args[1] == self: return quotient elif quotient.is_Integer and c.is_Number: return quotient elif self.is_Add: cs, ps = self.primitive() # assert cs >= 1 if c.is_Number and c is not S.NegativeOne: # assert c != 1 (handled at top) if cs is not S.One: if c.is_negative: xc = -(cs.extract_multiplicatively(-c)) else: xc = cs.extract_multiplicatively(c) if xc is not None: return xc*ps # rely on 2-arg Mul to restore Add return # |c| != 1 can only be extracted from cs if c == ps: return cs # check args of ps newargs = [] for arg in ps.args: newarg = arg.extract_multiplicatively(c) if newarg is None: return # all or nothing newargs.append(newarg) # args should be in same order so use unevaluated return if cs is not S.One: return Add._from_args([cs*t for t in newargs]) else: return Add._from_args(newargs) elif self.is_Mul: args = list(self.args) for i, arg in enumerate(args): newarg = arg.extract_multiplicatively(c) if newarg is not None: args[i] = newarg return Mul(*args) elif self.is_Pow: if c.is_Pow and c.base == self.base: new_exp = self.exp.extract_additively(c.exp) if new_exp is not None: return self.base ** (new_exp) elif c == self.base: new_exp = self.exp.extract_additively(1) if new_exp is not None: return self.base ** (new_exp) def extract_additively(self, c): """Return self - c if it's possible to subtract c from self and make all matching coefficients move towards zero, else return None. Examples ======== >>> from sympy.abc import x, y >>> e = 2*x + 3 >>> e.extract_additively(x + 1) x + 2 >>> e.extract_additively(3*x) >>> e.extract_additively(4) >>> (y*(x + 1)).extract_additively(x + 1) >>> ((x + 1)*(x + 2*y + 1) + 3).extract_additively(x + 1) (x + 1)*(x + 2*y) + 3 Sometimes auto-expansion will return a less simplified result than desired; gcd_terms might be used in such cases: >>> from sympy import gcd_terms >>> (4*x*(y + 1) + y).extract_additively(x) 4*x*(y + 1) + x*(4*y + 3) - x*(4*y + 4) + y >>> gcd_terms(_) x*(4*y + 3) + y See Also ======== extract_multiplicatively coeff as_coefficient """ c = sympify(c) if self is S.NaN: return None if c is S.Zero: return self elif c == self: return S.Zero elif self is S.Zero: return None if self.is_Number: if not c.is_Number: return None co = self diff = co - c # XXX should we match types? i.e should 3 - .1 succeed? if (co > 0 and diff > 0 and diff < co or co < 0 and diff < 0 and diff > co): return diff return None if c.is_Number: co, t = self.as_coeff_Add() xa = co.extract_additively(c) if xa is None: return None return xa + t # handle the args[0].is_Number case separately # since we will have trouble looking for the coeff of # a number. if c.is_Add and c.args[0].is_Number: # whole term as a term factor co = self.coeff(c) xa0 = (co.extract_additively(1) or 0)*c if xa0: diff = self - co*c return (xa0 + (diff.extract_additively(c) or diff)) or None # term-wise h, t = c.as_coeff_Add() sh, st = self.as_coeff_Add() xa = sh.extract_additively(h) if xa is None: return None xa2 = st.extract_additively(t) if xa2 is None: return None return xa + xa2 # whole term as a term factor co = self.coeff(c) xa0 = (co.extract_additively(1) or 0)*c if xa0: diff = self - co*c return (xa0 + (diff.extract_additively(c) or diff)) or None # term-wise coeffs = [] for a in Add.make_args(c): ac, at = a.as_coeff_Mul() co = self.coeff(at) if not co: return None coc, cot = co.as_coeff_Add() xa = coc.extract_additively(ac) if xa is None: return None self -= co*at coeffs.append((cot + xa)*at) coeffs.append(self) return Add(*coeffs) @property def expr_free_symbols(self): """ Like ``free_symbols``, but returns the free symbols only if they are contained in an expression node. Examples ======== >>> from sympy.abc import x, y >>> (x + y).expr_free_symbols {x, y} If the expression is contained in a non-expression object, don't return the free symbols. Compare: >>> from sympy import Tuple >>> t = Tuple(x + y) >>> t.expr_free_symbols set() >>> t.free_symbols {x, y} """ return {j for i in self.args for j in i.expr_free_symbols} def could_extract_minus_sign(self): """Return True if self is not in a canonical form with respect to its sign. For most expressions, e, there will be a difference in e and -e. When there is, True will be returned for one and False for the other; False will be returned if there is no difference. Examples ======== >>> from sympy.abc import x, y >>> e = x - y >>> {i.could_extract_minus_sign() for i in (e, -e)} {False, True} """ negative_self = -self if self == negative_self: return False # e.g. zoo*x == -zoo*x self_has_minus = (self.extract_multiplicatively(-1) is not None) negative_self_has_minus = ( (negative_self).extract_multiplicatively(-1) is not None) if self_has_minus != negative_self_has_minus: return self_has_minus else: if self.is_Add: # We choose the one with less arguments with minus signs all_args = len(self.args) negative_args = len([False for arg in self.args if arg.could_extract_minus_sign()]) positive_args = all_args - negative_args if positive_args > negative_args: return False elif positive_args < negative_args: return True elif self.is_Mul: # We choose the one with an odd number of minus signs num, den = self.as_numer_denom() args = Mul.make_args(num) + Mul.make_args(den) arg_signs = [arg.could_extract_minus_sign() for arg in args] negative_args = list(filter(None, arg_signs)) return len(negative_args) % 2 == 1 # As a last resort, we choose the one with greater value of .sort_key() return bool(self.sort_key() < negative_self.sort_key()) def extract_branch_factor(self, allow_half=False): """ Try to write self as ``exp_polar(2*pi*I*n)*z`` in a nice way. Return (z, n). >>> from sympy import exp_polar, I, pi >>> from sympy.abc import x, y >>> exp_polar(I*pi).extract_branch_factor() (exp_polar(I*pi), 0) >>> exp_polar(2*I*pi).extract_branch_factor() (1, 1) >>> exp_polar(-pi*I).extract_branch_factor() (exp_polar(I*pi), -1) >>> exp_polar(3*pi*I + x).extract_branch_factor() (exp_polar(x + I*pi), 1) >>> (y*exp_polar(-5*pi*I)*exp_polar(3*pi*I + 2*pi*x)).extract_branch_factor() (y*exp_polar(2*pi*x), -1) >>> exp_polar(-I*pi/2).extract_branch_factor() (exp_polar(-I*pi/2), 0) If allow_half is True, also extract exp_polar(I*pi): >>> exp_polar(I*pi).extract_branch_factor(allow_half=True) (1, 1/2) >>> exp_polar(2*I*pi).extract_branch_factor(allow_half=True) (1, 1) >>> exp_polar(3*I*pi).extract_branch_factor(allow_half=True) (1, 3/2) >>> exp_polar(-I*pi).extract_branch_factor(allow_half=True) (1, -1/2) """ from sympy import exp_polar, pi, I, ceiling, Add n = S(0) res = S(1) args = Mul.make_args(self) exps = [] for arg in args: if isinstance(arg, exp_polar): exps += [arg.exp] else: res *= arg piimult = S(0) extras = [] while exps: exp = exps.pop() if exp.is_Add: exps += exp.args continue if exp.is_Mul: coeff = exp.as_coefficient(pi*I) if coeff is not None: piimult += coeff continue extras += [exp] if not piimult.free_symbols: coeff = piimult tail = () else: coeff, tail = piimult.as_coeff_add(*piimult.free_symbols) # round down to nearest multiple of 2 branchfact = ceiling(coeff/2 - S(1)/2)*2 n += branchfact/2 c = coeff - branchfact if allow_half: nc = c.extract_additively(1) if nc is not None: n += S(1)/2 c = nc newexp = pi*I*Add(*((c, ) + tail)) + Add(*extras) if newexp != 0: res *= exp_polar(newexp) return res, n def _eval_is_polynomial(self, syms): if self.free_symbols.intersection(syms) == set([]): return True return False def is_polynomial(self, *syms): r""" Return True if self is a polynomial in syms and False otherwise. This checks if self is an exact polynomial in syms. This function returns False for expressions that are "polynomials" with symbolic exponents. Thus, you should be able to apply polynomial algorithms to expressions for which this returns True, and Poly(expr, \*syms) should work if and only if expr.is_polynomial(\*syms) returns True. The polynomial does not have to be in expanded form. If no symbols are given, all free symbols in the expression will be used. This is not part of the assumptions system. You cannot do Symbol('z', polynomial=True). Examples ======== >>> from sympy import Symbol >>> x = Symbol('x') >>> ((x**2 + 1)**4).is_polynomial(x) True >>> ((x**2 + 1)**4).is_polynomial() True >>> (2**x + 1).is_polynomial(x) False >>> n = Symbol('n', nonnegative=True, integer=True) >>> (x**n + 1).is_polynomial(x) False This function does not attempt any nontrivial simplifications that may result in an expression that does not appear to be a polynomial to become one. >>> from sympy import sqrt, factor, cancel >>> y = Symbol('y', positive=True) >>> a = sqrt(y**2 + 2*y + 1) >>> a.is_polynomial(y) False >>> factor(a) y + 1 >>> factor(a).is_polynomial(y) True >>> b = (y**2 + 2*y + 1)/(y + 1) >>> b.is_polynomial(y) False >>> cancel(b) y + 1 >>> cancel(b).is_polynomial(y) True See also .is_rational_function() """ if syms: syms = set(map(sympify, syms)) else: syms = self.free_symbols if syms.intersection(self.free_symbols) == set([]): # constant polynomial return True else: return self._eval_is_polynomial(syms) def _eval_is_rational_function(self, syms): if self.free_symbols.intersection(syms) == set([]): return True return False def is_rational_function(self, *syms): """ Test whether function is a ratio of two polynomials in the given symbols, syms. When syms is not given, all free symbols will be used. The rational function does not have to be in expanded or in any kind of canonical form. This function returns False for expressions that are "rational functions" with symbolic exponents. Thus, you should be able to call .as_numer_denom() and apply polynomial algorithms to the result for expressions for which this returns True. This is not part of the assumptions system. You cannot do Symbol('z', rational_function=True). Examples ======== >>> from sympy import Symbol, sin >>> from sympy.abc import x, y >>> (x/y).is_rational_function() True >>> (x**2).is_rational_function() True >>> (x/sin(y)).is_rational_function(y) False >>> n = Symbol('n', integer=True) >>> (x**n + 1).is_rational_function(x) False This function does not attempt any nontrivial simplifications that may result in an expression that does not appear to be a rational function to become one. >>> from sympy import sqrt, factor >>> y = Symbol('y', positive=True) >>> a = sqrt(y**2 + 2*y + 1)/y >>> a.is_rational_function(y) False >>> factor(a) (y + 1)/y >>> factor(a).is_rational_function(y) True See also is_algebraic_expr(). """ if self in [S.NaN, S.Infinity, -S.Infinity, S.ComplexInfinity]: return False if syms: syms = set(map(sympify, syms)) else: syms = self.free_symbols if syms.intersection(self.free_symbols) == set([]): # constant rational function return True else: return self._eval_is_rational_function(syms) def _eval_is_algebraic_expr(self, syms): if self.free_symbols.intersection(syms) == set([]): return True return False def is_algebraic_expr(self, *syms): """ This tests whether a given expression is algebraic or not, in the given symbols, syms. When syms is not given, all free symbols will be used. The rational function does not have to be in expanded or in any kind of canonical form. This function returns False for expressions that are "algebraic expressions" with symbolic exponents. This is a simple extension to the is_rational_function, including rational exponentiation. Examples ======== >>> from sympy import Symbol, sqrt >>> x = Symbol('x', real=True) >>> sqrt(1 + x).is_rational_function() False >>> sqrt(1 + x).is_algebraic_expr() True This function does not attempt any nontrivial simplifications that may result in an expression that does not appear to be an algebraic expression to become one. >>> from sympy import exp, factor >>> a = sqrt(exp(x)**2 + 2*exp(x) + 1)/(exp(x) + 1) >>> a.is_algebraic_expr(x) False >>> factor(a).is_algebraic_expr() True See Also ======== is_rational_function() References ========== - https://en.wikipedia.org/wiki/Algebraic_expression """ if syms: syms = set(map(sympify, syms)) else: syms = self.free_symbols if syms.intersection(self.free_symbols) == set([]): # constant algebraic expression return True else: return self._eval_is_algebraic_expr(syms) ################################################################################### ##################### SERIES, LEADING TERM, LIMIT, ORDER METHODS ################## ################################################################################### def series(self, x=None, x0=0, n=6, dir="+", logx=None): """ Series expansion of "self" around ``x = x0`` yielding either terms of the series one by one (the lazy series given when n=None), else all the terms at once when n != None. Returns the series expansion of "self" around the point ``x = x0`` with respect to ``x`` up to ``O((x - x0)**n, x, x0)`` (default n is 6). If ``x=None`` and ``self`` is univariate, the univariate symbol will be supplied, otherwise an error will be raised. >>> from sympy import cos, exp >>> from sympy.abc import x, y >>> cos(x).series() 1 - x**2/2 + x**4/24 + O(x**6) >>> cos(x).series(n=4) 1 - x**2/2 + O(x**4) >>> cos(x).series(x, x0=1, n=2) cos(1) - (x - 1)*sin(1) + O((x - 1)**2, (x, 1)) >>> e = cos(x + exp(y)) >>> e.series(y, n=2) cos(x + 1) - y*sin(x + 1) + O(y**2) >>> e.series(x, n=2) cos(exp(y)) - x*sin(exp(y)) + O(x**2) If ``n=None`` then a generator of the series terms will be returned. >>> term=cos(x).series(n=None) >>> [next(term) for i in range(2)] [1, -x**2/2] For ``dir=+`` (default) the series is calculated from the right and for ``dir=-`` the series from the left. For smooth functions this flag will not alter the results. >>> abs(x).series(dir="+") x >>> abs(x).series(dir="-") -x """ from sympy import collect, Dummy, Order, Rational, Symbol, ceiling if x is None: syms = self.free_symbols if not syms: return self elif len(syms) > 1: raise ValueError('x must be given for multivariate functions.') x = syms.pop() if isinstance(x, Symbol): dep = x in self.free_symbols else: d = Dummy() dep = d in self.xreplace({x: d}).free_symbols if not dep: if n is None: return (s for s in [self]) else: return self if len(dir) != 1 or dir not in '+-': raise ValueError("Dir must be '+' or '-'") if x0 in [S.Infinity, S.NegativeInfinity]: sgn = 1 if x0 is S.Infinity else -1 s = self.subs(x, sgn/x).series(x, n=n, dir='+') if n is None: return (si.subs(x, sgn/x) for si in s) return s.subs(x, sgn/x) # use rep to shift origin to x0 and change sign (if dir is negative) # and undo the process with rep2 if x0 or dir == '-': if dir == '-': rep = -x + x0 rep2 = -x rep2b = x0 else: rep = x + x0 rep2 = x rep2b = -x0 s = self.subs(x, rep).series(x, x0=0, n=n, dir='+', logx=logx) if n is None: # lseries... return (si.subs(x, rep2 + rep2b) for si in s) return s.subs(x, rep2 + rep2b) # from here on it's x0=0 and dir='+' handling if x.is_positive is x.is_negative is None or x.is_Symbol is not True: # replace x with an x that has a positive assumption xpos = Dummy('x', positive=True, finite=True) rv = self.subs(x, xpos).series(xpos, x0, n, dir, logx=logx) if n is None: return (s.subs(xpos, x) for s in rv) else: return rv.subs(xpos, x) if n is not None: # nseries handling s1 = self._eval_nseries(x, n=n, logx=logx) o = s1.getO() or S.Zero if o: # make sure the requested order is returned ngot = o.getn() if ngot > n: # leave o in its current form (e.g. with x*log(x)) so # it eats terms properly, then replace it below if n != 0: s1 += o.subs(x, x**Rational(n, ngot)) else: s1 += Order(1, x) elif ngot < n: # increase the requested number of terms to get the desired # number keep increasing (up to 9) until the received order # is different than the original order and then predict how # many additional terms are needed for more in range(1, 9): s1 = self._eval_nseries(x, n=n + more, logx=logx) newn = s1.getn() if newn != ngot: ndo = n + ceiling((n - ngot)*more/(newn - ngot)) s1 = self._eval_nseries(x, n=ndo, logx=logx) while s1.getn() < n: s1 = self._eval_nseries(x, n=ndo, logx=logx) ndo += 1 break else: raise ValueError('Could not calculate %s terms for %s' % (str(n), self)) s1 += Order(x**n, x) o = s1.getO() s1 = s1.removeO() else: o = Order(x**n, x) s1done = s1.doit() if (s1done + o).removeO() == s1done: o = S.Zero try: return collect(s1, x) + o except NotImplementedError: return s1 + o else: # lseries handling def yield_lseries(s): """Return terms of lseries one at a time.""" for si in s: if not si.is_Add: yield si continue # yield terms 1 at a time if possible # by increasing order until all the # terms have been returned yielded = 0 o = Order(si, x)*x ndid = 0 ndo = len(si.args) while 1: do = (si - yielded + o).removeO() o *= x if not do or do.is_Order: continue if do.is_Add: ndid += len(do.args) else: ndid += 1 yield do if ndid == ndo: break yielded += do return yield_lseries(self.removeO()._eval_lseries(x, logx=logx)) def taylor_term(self, n, x, *previous_terms): """General method for the taylor term. This method is slow, because it differentiates n-times. Subclasses can redefine it to make it faster by using the "previous_terms". """ from sympy import Dummy, factorial x = sympify(x) _x = Dummy('x') return self.subs(x, _x).diff(_x, n).subs(_x, x).subs(x, 0) * x**n / factorial(n) def lseries(self, x=None, x0=0, dir='+', logx=None): """ Wrapper for series yielding an iterator of the terms of the series. Note: an infinite series will yield an infinite iterator. The following, for exaxmple, will never terminate. It will just keep printing terms of the sin(x) series:: for term in sin(x).lseries(x): print term The advantage of lseries() over nseries() is that many times you are just interested in the next term in the series (i.e. the first term for example), but you don't know how many you should ask for in nseries() using the "n" parameter. See also nseries(). """ return self.series(x, x0, n=None, dir=dir, logx=logx) def _eval_lseries(self, x, logx=None): # default implementation of lseries is using nseries(), and adaptively # increasing the "n". As you can see, it is not very efficient, because # we are calculating the series over and over again. Subclasses should # override this method and implement much more efficient yielding of # terms. n = 0 series = self._eval_nseries(x, n=n, logx=logx) if not series.is_Order: if series.is_Add: yield series.removeO() else: yield series return while series.is_Order: n += 1 series = self._eval_nseries(x, n=n, logx=logx) e = series.removeO() yield e while 1: while 1: n += 1 series = self._eval_nseries(x, n=n, logx=logx).removeO() if e != series: break yield series - e e = series def nseries(self, x=None, x0=0, n=6, dir='+', logx=None): """ Wrapper to _eval_nseries if assumptions allow, else to series. If x is given, x0 is 0, dir='+', and self has x, then _eval_nseries is called. This calculates "n" terms in the innermost expressions and then builds up the final series just by "cross-multiplying" everything out. The optional ``logx`` parameter can be used to replace any log(x) in the returned series with a symbolic value to avoid evaluating log(x) at 0. A symbol to use in place of log(x) should be provided. Advantage -- it's fast, because we don't have to determine how many terms we need to calculate in advance. Disadvantage -- you may end up with less terms than you may have expected, but the O(x**n) term appended will always be correct and so the result, though perhaps shorter, will also be correct. If any of those assumptions is not met, this is treated like a wrapper to series which will try harder to return the correct number of terms. See also lseries(). Examples ======== >>> from sympy import sin, log, Symbol >>> from sympy.abc import x, y >>> sin(x).nseries(x, 0, 6) x - x**3/6 + x**5/120 + O(x**6) >>> log(x+1).nseries(x, 0, 5) x - x**2/2 + x**3/3 - x**4/4 + O(x**5) Handling of the ``logx`` parameter --- in the following example the expansion fails since ``sin`` does not have an asymptotic expansion at -oo (the limit of log(x) as x approaches 0): >>> e = sin(log(x)) >>> e.nseries(x, 0, 6) Traceback (most recent call last): ... PoleError: ... ... >>> logx = Symbol('logx') >>> e.nseries(x, 0, 6, logx=logx) sin(logx) In the following example, the expansion works but gives only an Order term unless the ``logx`` parameter is used: >>> e = x**y >>> e.nseries(x, 0, 2) O(log(x)**2) >>> e.nseries(x, 0, 2, logx=logx) exp(logx*y) """ if x and not x in self.free_symbols: return self if x is None or x0 or dir != '+': # {see XPOS above} or (x.is_positive == x.is_negative == None): return self.series(x, x0, n, dir) else: return self._eval_nseries(x, n=n, logx=logx) def _eval_nseries(self, x, n, logx): """ Return terms of series for self up to O(x**n) at x=0 from the positive direction. This is a method that should be overridden in subclasses. Users should never call this method directly (use .nseries() instead), so you don't have to write docstrings for _eval_nseries(). """ from sympy.utilities.misc import filldedent raise NotImplementedError(filldedent(""" The _eval_nseries method should be added to %s to give terms up to O(x**n) at x=0 from the positive direction so it is available when nseries calls it.""" % self.func) ) def limit(self, x, xlim, dir='+'): """ Compute limit x->xlim. """ from sympy.series.limits import limit return limit(self, x, xlim, dir) def compute_leading_term(self, x, logx=None): """ as_leading_term is only allowed for results of .series() This is a wrapper to compute a series first. """ from sympy import Dummy, log from sympy.series.gruntz import calculate_series if self.removeO() == 0: return self if logx is None: d = Dummy('logx') s = calculate_series(self, x, d).subs(d, log(x)) else: s = calculate_series(self, x, logx) return s.as_leading_term(x) @cacheit def as_leading_term(self, *symbols): """ Returns the leading (nonzero) term of the series expansion of self. The _eval_as_leading_term routines are used to do this, and they must always return a non-zero value. Examples ======== >>> from sympy.abc import x >>> (1 + x + x**2).as_leading_term(x) 1 >>> (1/x**2 + x + x**2).as_leading_term(x) x**(-2) """ from sympy import powsimp if len(symbols) > 1: c = self for x in symbols: c = c.as_leading_term(x) return c elif not symbols: return self x = sympify(symbols[0]) if not x.is_symbol: raise ValueError('expecting a Symbol but got %s' % x) if x not in self.free_symbols: return self obj = self._eval_as_leading_term(x) if obj is not None: return powsimp(obj, deep=True, combine='exp') raise NotImplementedError('as_leading_term(%s, %s)' % (self, x)) def _eval_as_leading_term(self, x): return self def as_coeff_exponent(self, x): """ ``c*x**e -> c,e`` where x can be any symbolic expression. """ from sympy import collect s = collect(self, x) c, p = s.as_coeff_mul(x) if len(p) == 1: b, e = p[0].as_base_exp() if b == x: return c, e return s, S.Zero def leadterm(self, x): """ Returns the leading term a*x**b as a tuple (a, b). Examples ======== >>> from sympy.abc import x >>> (1+x+x**2).leadterm(x) (1, 0) >>> (1/x**2+x+x**2).leadterm(x) (1, -2) """ from sympy import Dummy, log l = self.as_leading_term(x) d = Dummy('logx') if l.has(log(x)): l = l.subs(log(x), d) c, e = l.as_coeff_exponent(x) if x in c.free_symbols: from sympy.utilities.misc import filldedent raise ValueError(filldedent(""" cannot compute leadterm(%s, %s). The coefficient should have been free of x but got %s""" % (self, x, c))) c = c.subs(d, log(x)) return c, e def as_coeff_Mul(self, rational=False): """Efficiently extract the coefficient of a product. """ return S.One, self def as_coeff_Add(self, rational=False): """Efficiently extract the coefficient of a summation. """ return S.Zero, self def fps(self, x=None, x0=0, dir=1, hyper=True, order=4, rational=True, full=False): """ Compute formal power power series of self. See the docstring of the :func:`fps` function in sympy.series.formal for more information. """ from sympy.series.formal import fps return fps(self, x, x0, dir, hyper, order, rational, full) def fourier_series(self, limits=None): """Compute fourier sine/cosine series of self. See the docstring of the :func:`fourier_series` in sympy.series.fourier for more information. """ from sympy.series.fourier import fourier_series return fourier_series(self, limits) ################################################################################### ##################### DERIVATIVE, INTEGRAL, FUNCTIONAL METHODS #################### ################################################################################### def diff(self, *symbols, **assumptions): assumptions.setdefault("evaluate", True) return Derivative(self, *symbols, **assumptions) ########################################################################### ###################### EXPRESSION EXPANSION METHODS ####################### ########################################################################### # Relevant subclasses should override _eval_expand_hint() methods. See # the docstring of expand() for more info. def _eval_expand_complex(self, **hints): real, imag = self.as_real_imag(**hints) return real + S.ImaginaryUnit*imag @staticmethod def _expand_hint(expr, hint, deep=True, **hints): """ Helper for ``expand()``. Recursively calls ``expr._eval_expand_hint()``. Returns ``(expr, hit)``, where expr is the (possibly) expanded ``expr`` and ``hit`` is ``True`` if ``expr`` was truly expanded and ``False`` otherwise. """ hit = False # XXX: Hack to support non-Basic args # | # V if deep and getattr(expr, 'args', ()) and not expr.is_Atom: sargs = [] for arg in expr.args: arg, arghit = Expr._expand_hint(arg, hint, **hints) hit |= arghit sargs.append(arg) if hit: expr = expr.func(*sargs) if hasattr(expr, hint): newexpr = getattr(expr, hint)(**hints) if newexpr != expr: return (newexpr, True) return (expr, hit) @cacheit def expand(self, deep=True, modulus=None, power_base=True, power_exp=True, mul=True, log=True, multinomial=True, basic=True, **hints): """ Expand an expression using hints. See the docstring of the expand() function in sympy.core.function for more information. """ from sympy.simplify.radsimp import fraction hints.update(power_base=power_base, power_exp=power_exp, mul=mul, log=log, multinomial=multinomial, basic=basic) expr = self if hints.pop('frac', False): n, d = [a.expand(deep=deep, modulus=modulus, **hints) for a in fraction(self)] return n/d elif hints.pop('denom', False): n, d = fraction(self) return n/d.expand(deep=deep, modulus=modulus, **hints) elif hints.pop('numer', False): n, d = fraction(self) return n.expand(deep=deep, modulus=modulus, **hints)/d # Although the hints are sorted here, an earlier hint may get applied # at a given node in the expression tree before another because of how # the hints are applied. e.g. expand(log(x*(y + z))) -> log(x*y + # x*z) because while applying log at the top level, log and mul are # applied at the deeper level in the tree so that when the log at the # upper level gets applied, the mul has already been applied at the # lower level. # Additionally, because hints are only applied once, the expression # may not be expanded all the way. For example, if mul is applied # before multinomial, x*(x + 1)**2 won't be expanded all the way. For # now, we just use a special case to make multinomial run before mul, # so that at least polynomials will be expanded all the way. In the # future, smarter heuristics should be applied. # TODO: Smarter heuristics def _expand_hint_key(hint): """Make multinomial come before mul""" if hint == 'mul': return 'mulz' return hint for hint in sorted(hints.keys(), key=_expand_hint_key): use_hint = hints[hint] if use_hint: hint = '_eval_expand_' + hint expr, hit = Expr._expand_hint(expr, hint, deep=deep, **hints) while True: was = expr if hints.get('multinomial', False): expr, _ = Expr._expand_hint( expr, '_eval_expand_multinomial', deep=deep, **hints) if hints.get('mul', False): expr, _ = Expr._expand_hint( expr, '_eval_expand_mul', deep=deep, **hints) if hints.get('log', False): expr, _ = Expr._expand_hint( expr, '_eval_expand_log', deep=deep, **hints) if expr == was: break if modulus is not None: modulus = sympify(modulus) if not modulus.is_Integer or modulus <= 0: raise ValueError( "modulus must be a positive integer, got %s" % modulus) terms = [] for term in Add.make_args(expr): coeff, tail = term.as_coeff_Mul(rational=True) coeff %= modulus if coeff: terms.append(coeff*tail) expr = Add(*terms) return expr ########################################################################### ################### GLOBAL ACTION VERB WRAPPER METHODS #################### ########################################################################### def integrate(self, *args, **kwargs): """See the integrate function in sympy.integrals""" from sympy.integrals import integrate return integrate(self, *args, **kwargs) def simplify(self, ratio=1.7, measure=None, rational=False, inverse=False): """See the simplify function in sympy.simplify""" from sympy.simplify import simplify from sympy.core.function import count_ops measure = measure or count_ops return simplify(self, ratio, measure) def nsimplify(self, constants=[], tolerance=None, full=False): """See the nsimplify function in sympy.simplify""" from sympy.simplify import nsimplify return nsimplify(self, constants, tolerance, full) def separate(self, deep=False, force=False): """See the separate function in sympy.simplify""" from sympy.core.function import expand_power_base return expand_power_base(self, deep=deep, force=force) def collect(self, syms, func=None, evaluate=True, exact=False, distribute_order_term=True): """See the collect function in sympy.simplify""" from sympy.simplify import collect return collect(self, syms, func, evaluate, exact, distribute_order_term) def together(self, *args, **kwargs): """See the together function in sympy.polys""" from sympy.polys import together return together(self, *args, **kwargs) def apart(self, x=None, **args): """See the apart function in sympy.polys""" from sympy.polys import apart return apart(self, x, **args) def ratsimp(self): """See the ratsimp function in sympy.simplify""" from sympy.simplify import ratsimp return ratsimp(self) def trigsimp(self, **args): """See the trigsimp function in sympy.simplify""" from sympy.simplify import trigsimp return trigsimp(self, **args) def radsimp(self, **kwargs): """See the radsimp function in sympy.simplify""" from sympy.simplify import radsimp return radsimp(self, **kwargs) def powsimp(self, *args, **kwargs): """See the powsimp function in sympy.simplify""" from sympy.simplify import powsimp return powsimp(self, *args, **kwargs) def combsimp(self): """See the combsimp function in sympy.simplify""" from sympy.simplify import combsimp return combsimp(self) def gammasimp(self): """See the gammasimp function in sympy.simplify""" from sympy.simplify import gammasimp return gammasimp(self) def factor(self, *gens, **args): """See the factor() function in sympy.polys.polytools""" from sympy.polys import factor return factor(self, *gens, **args) def refine(self, assumption=True): """See the refine function in sympy.assumptions""" from sympy.assumptions import refine return refine(self, assumption) def cancel(self, *gens, **args): """See the cancel function in sympy.polys""" from sympy.polys import cancel return cancel(self, *gens, **args) def invert(self, g, *gens, **args): """Return the multiplicative inverse of ``self`` mod ``g`` where ``self`` (and ``g``) may be symbolic expressions). See Also ======== sympy.core.numbers.mod_inverse, sympy.polys.polytools.invert """ from sympy.polys.polytools import invert from sympy.core.numbers import mod_inverse if self.is_number and getattr(g, 'is_number', True): return mod_inverse(self, g) return invert(self, g, *gens, **args) def round(self, p=0): """Return x rounded to the given decimal place. If a complex number would results, apply round to the real and imaginary components of the number. Examples ======== >>> from sympy import pi, E, I, S, Add, Mul, Number >>> S(10.5).round() 11. >>> pi.round() 3. >>> pi.round(2) 3.14 >>> (2*pi + E*I).round() 6. + 3.*I The round method has a chopping effect: >>> (2*pi + I/10).round() 6. >>> (pi/10 + 2*I).round() 2.*I >>> (pi/10 + E*I).round(2) 0.31 + 2.72*I Notes ===== Do not confuse the Python builtin function, round, with the SymPy method of the same name. The former always returns a float (or raises an error if applied to a complex value) while the latter returns either a Number or a complex number: >>> isinstance(round(S(123), -2), Number) False >>> isinstance(S(123).round(-2), Number) True >>> isinstance((3*I).round(), Mul) True >>> isinstance((1 + 3*I).round(), Add) True """ from sympy import Float x = self if not x.is_number: raise TypeError("can't round symbolic expression") if not x.is_Atom: xn = x.n(2) if not pure_complex(xn, or_real=True): raise TypeError('Expected a number but got %s:' % getattr(getattr(x,'func', x), '__name__', type(x))) elif x in (S.NaN, S.Infinity, S.NegativeInfinity, S.ComplexInfinity): return x if not x.is_real: i, r = x.as_real_imag() return i.round(p) + S.ImaginaryUnit*r.round(p) if not x: return x p = int(p) precs = [f._prec for f in x.atoms(Float)] dps = prec_to_dps(max(precs)) if precs else None mag_first_dig = _mag(x) allow = digits_needed = mag_first_dig + p if dps is not None and allow > dps: allow = dps mag = Pow(10, p) # magnitude needed to bring digit p to units place xwas = x x += 1/(2*mag) # add the half for rounding i10 = 10*mag*x.n((dps if dps is not None else digits_needed) + 1) if i10.is_negative: x = xwas - 1/(2*mag) # should have gone the other way i10 = 10*mag*x.n((dps if dps is not None else digits_needed) + 1) rv = -(Integer(-i10)//10) else: rv = Integer(i10)//10 q = 1 if p > 0: q = mag elif p < 0: rv /= mag rv = Rational(rv, q) if rv.is_Integer: # use str or else it won't be a float return Float(str(rv), digits_needed) else: if not allow and rv > self: allow += 1 return Float(rv, allow) class AtomicExpr(Atom, Expr): """ A parent class for object which are both atoms and Exprs. For example: Symbol, Number, Rational, Integer, ... But not: Add, Mul, Pow, ... """ is_number = False is_Atom = True __slots__ = [] def _eval_derivative(self, s): if self == s: return S.One return S.Zero def _eval_derivative_n_times(self, s, n): from sympy import Piecewise, Eq from sympy import Tuple from sympy.matrices.common import MatrixCommon if isinstance(s, (MatrixCommon, Tuple, Iterable)): return super(AtomicExpr, self)._eval_derivative_n_times(s, n) if self == s: return Piecewise((self, Eq(n, 0)), (1, Eq(n, 1)), (0, True)) else: return Piecewise((self, Eq(n, 0)), (0, True)) def _eval_is_polynomial(self, syms): return True def _eval_is_rational_function(self, syms): return True def _eval_is_algebraic_expr(self, syms): return True def _eval_nseries(self, x, n, logx): return self @property def expr_free_symbols(self): return {self} def _mag(x): """Return integer ``i`` such that .1 <= x/10**i < 1 Examples ======== >>> from sympy.core.expr import _mag >>> from sympy import Float >>> _mag(Float(.1)) 0 >>> _mag(Float(.01)) -1 >>> _mag(Float(1234)) 4 """ from math import log10, ceil, log from sympy import Float xpos = abs(x.n()) if not xpos: return S.Zero try: mag_first_dig = int(ceil(log10(xpos))) except (ValueError, OverflowError): mag_first_dig = int(ceil(Float(mpf_log(xpos._mpf_, 53))/log(10))) # check that we aren't off by 1 if (xpos/10**mag_first_dig) >= 1: assert 1 <= (xpos/10**mag_first_dig) < 10 mag_first_dig += 1 return mag_first_dig class UnevaluatedExpr(Expr): """ Expression that is not evaluated unless released. Examples ======== >>> from sympy import UnevaluatedExpr >>> from sympy.abc import a, b, x, y >>> x*(1/x) 1 >>> x*UnevaluatedExpr(1/x) x*1/x """ def __new__(cls, arg, **kwargs): arg = _sympify(arg) obj = Expr.__new__(cls, arg, **kwargs) return obj def doit(self, **kwargs): if kwargs.get("deep", True): return self.args[0].doit(**kwargs) else: return self.args[0] def _n2(a, b): """Return (a - b).evalf(2) if a and b are comparable, else None. This should only be used when a and b are already sympified. """ # /!\ it is very important (see issue 8245) not to # use a re-evaluated number in the calculation of dif if a.is_comparable and b.is_comparable: dif = (a - b).evalf(2) if dif.is_comparable: return dif from .mul import Mul from .add import Add from .power import Pow from .function import Derivative, Function from .mod import Mod from .exprtools import factor_terms from .numbers import Integer, Rational

d13b5542ccd15a92a662caf6f235d4f7228d6fb116b4eec5a0e9a27d513abe5d

from __future__ import print_function, division from .add import _unevaluated_Add, Add from .basic import S from .compatibility import ordered from .expr import Expr from .evalf import EvalfMixin from .sympify import _sympify from .evaluate import global_evaluate from sympy.logic.boolalg import Boolean, BooleanAtom __all__ = ( 'Rel', 'Eq', 'Ne', 'Lt', 'Le', 'Gt', 'Ge', 'Relational', 'Equality', 'Unequality', 'StrictLessThan', 'LessThan', 'StrictGreaterThan', 'GreaterThan', ) # Note, see issue 4986. Ideally, we wouldn't want to subclass both Boolean # and Expr. def _canonical(cond): # return a condition in which all relationals are canonical try: reps = dict([(r, r.canonical) for r in cond.atoms(Relational)]) return cond.xreplace(reps) except AttributeError: return cond class Relational(Boolean, Expr, EvalfMixin): """Base class for all relation types. Subclasses of Relational should generally be instantiated directly, but Relational can be instantiated with a valid `rop` value to dispatch to the appropriate subclass. Parameters ========== rop : str or None Indicates what subclass to instantiate. Valid values can be found in the keys of Relational.ValidRelationalOperator. Examples ======== >>> from sympy import Rel >>> from sympy.abc import x, y >>> Rel(y, x + x**2, '==') Eq(y, x**2 + x) """ __slots__ = [] is_Relational = True # ValidRelationOperator - Defined below, because the necessary classes # have not yet been defined def __new__(cls, lhs, rhs, rop=None, **assumptions): # If called by a subclass, do nothing special and pass on to Expr. if cls is not Relational: return Expr.__new__(cls, lhs, rhs, **assumptions) # If called directly with an operator, look up the subclass # corresponding to that operator and delegate to it try: cls = cls.ValidRelationOperator[rop] rv = cls(lhs, rhs, **assumptions) # /// drop when Py2 is no longer supported # validate that Booleans are not being used in a relational # other than Eq/Ne; if isinstance(rv, (Eq, Ne)): pass elif isinstance(rv, Relational): # could it be otherwise? from sympy.core.symbol import Symbol from sympy.logic.boolalg import Boolean for a in rv.args: if isinstance(a, Symbol): continue if isinstance(a, Boolean): from sympy.utilities.misc import filldedent raise TypeError(filldedent(''' A Boolean argument can only be used in Eq and Ne; all other relationals expect real expressions. ''')) # \\\ return rv except KeyError: raise ValueError( "Invalid relational operator symbol: %r" % rop) @property def lhs(self): """The left-hand side of the relation.""" return self._args[0] @property def rhs(self): """The right-hand side of the relation.""" return self._args[1] @property def reversed(self): """Return the relationship with sides (and sign) reversed. Examples ======== >>> from sympy import Eq >>> from sympy.abc import x >>> Eq(x, 1) Eq(x, 1) >>> _.reversed Eq(1, x) >>> x < 1 x < 1 >>> _.reversed 1 > x """ ops = {Gt: Lt, Ge: Le, Lt: Gt, Le: Ge} a, b = self.args return ops.get(self.func, self.func)(b, a, evaluate=False) def _eval_evalf(self, prec): return self.func(*[s._evalf(prec) for s in self.args]) @property def canonical(self): """Return a canonical form of the relational by putting a Number on the rhs else ordering the args. No other simplification is attempted. Examples ======== >>> from sympy.abc import x, y >>> x < 2 x < 2 >>> _.reversed.canonical x < 2 >>> (-y < x).canonical x > -y >>> (-y > x).canonical x < -y """ args = self.args r = self if r.rhs.is_Number: if r.lhs.is_Number and r.lhs > r.rhs: r = r.reversed elif r.lhs.is_Number: r = r.reversed elif tuple(ordered(args)) != args: r = r.reversed return r def equals(self, other, failing_expression=False): """Return True if the sides of the relationship are mathematically identical and the type of relationship is the same. If failing_expression is True, return the expression whose truth value was unknown.""" if isinstance(other, Relational): if self == other or self.reversed == other: return True a, b = self, other if a.func in (Eq, Ne) or b.func in (Eq, Ne): if a.func != b.func: return False l, r = [i.equals(j, failing_expression=failing_expression) for i, j in zip(a.args, b.args)] if l is True: return r if r is True: return l lr, rl = [i.equals(j, failing_expression=failing_expression) for i, j in zip(a.args, b.reversed.args)] if lr is True: return rl if rl is True: return lr e = (l, r, lr, rl) if all(i is False for i in e): return False for i in e: if i not in (True, False): return i else: if b.func != a.func: b = b.reversed if a.func != b.func: return False l = a.lhs.equals(b.lhs, failing_expression=failing_expression) if l is False: return False r = a.rhs.equals(b.rhs, failing_expression=failing_expression) if r is False: return False if l is True: return r return l def _eval_simplify(self, ratio, measure, rational, inverse): r = self r = r.func(*[i.simplify(ratio=ratio, measure=measure, rational=rational, inverse=inverse) for i in r.args]) if r.is_Relational: dif = r.lhs - r.rhs # replace dif with a valid Number that will # allow a definitive comparison with 0 v = None if dif.is_comparable: v = dif.n(2) elif dif.equals(0): # XXX this is expensive v = S.Zero if v is not None: r = r.func._eval_relation(v, S.Zero) r = r.canonical if measure(r) < ratio*measure(self): return r else: return self def __nonzero__(self): raise TypeError("cannot determine truth value of Relational") __bool__ = __nonzero__ def _eval_as_set(self): # self is univariate and periodicity(self, x) in (0, None) from sympy.solvers.inequalities import solve_univariate_inequality syms = self.free_symbols assert len(syms) == 1 x = syms.pop() return solve_univariate_inequality(self, x, relational=False) @property def binary_symbols(self): # override where necessary return set() Rel = Relational class Equality(Relational): """An equal relation between two objects. Represents that two objects are equal. If they can be easily shown to be definitively equal (or unequal), this will reduce to True (or False). Otherwise, the relation is maintained as an unevaluated Equality object. Use the ``simplify`` function on this object for more nontrivial evaluation of the equality relation. As usual, the keyword argument ``evaluate=False`` can be used to prevent any evaluation. Examples ======== >>> from sympy import Eq, simplify, exp, cos >>> from sympy.abc import x, y >>> Eq(y, x + x**2) Eq(y, x**2 + x) >>> Eq(2, 5) False >>> Eq(2, 5, evaluate=False) Eq(2, 5) >>> _.doit() False >>> Eq(exp(x), exp(x).rewrite(cos)) Eq(exp(x), sinh(x) + cosh(x)) >>> simplify(_) True See Also ======== sympy.logic.boolalg.Equivalent : for representing equality between two boolean expressions Notes ===== This class is not the same as the == operator. The == operator tests for exact structural equality between two expressions; this class compares expressions mathematically. If either object defines an `_eval_Eq` method, it can be used in place of the default algorithm. If `lhs._eval_Eq(rhs)` or `rhs._eval_Eq(lhs)` returns anything other than None, that return value will be substituted for the Equality. If None is returned by `_eval_Eq`, an Equality object will be created as usual. Since this object is already an expression, it does not respond to the method `as_expr` if one tries to create `x - y` from Eq(x, y). This can be done with the `rewrite(Add)` method. """ rel_op = '==' __slots__ = [] is_Equality = True def __new__(cls, lhs, rhs=0, **options): from sympy.core.add import Add from sympy.core.logic import fuzzy_bool from sympy.core.expr import _n2 from sympy.simplify.simplify import clear_coefficients lhs = _sympify(lhs) rhs = _sympify(rhs) evaluate = options.pop('evaluate', global_evaluate[0]) if evaluate: # If one expression has an _eval_Eq, return its results. if hasattr(lhs, '_eval_Eq'): r = lhs._eval_Eq(rhs) if r is not None: return r if hasattr(rhs, '_eval_Eq'): r = rhs._eval_Eq(lhs) if r is not None: return r # If expressions have the same structure, they must be equal. if lhs == rhs: return S.true # e.g. True == True elif all(isinstance(i, BooleanAtom) for i in (rhs, lhs)): return S.false # True != False elif not (lhs.is_Symbol or rhs.is_Symbol) and ( isinstance(lhs, Boolean) != isinstance(rhs, Boolean)): return S.false # only Booleans can equal Booleans # check finiteness fin = L, R = [i.is_finite for i in (lhs, rhs)] if None not in fin: if L != R: return S.false if L is False: if lhs == -rhs: # Eq(oo, -oo) return S.false return S.true elif None in fin and False in fin: return Relational.__new__(cls, lhs, rhs, **options) if all(isinstance(i, Expr) for i in (lhs, rhs)): # see if the difference evaluates dif = lhs - rhs z = dif.is_zero if z is not None: if z is False and dif.is_commutative: # issue 10728 return S.false if z: return S.true # evaluate numerically if possible n2 = _n2(lhs, rhs) if n2 is not None: return _sympify(n2 == 0) # see if the ratio evaluates n, d = dif.as_numer_denom() rv = None if n.is_zero: rv = d.is_nonzero elif n.is_finite: if d.is_infinite: rv = S.true elif n.is_zero is False: rv = d.is_infinite if rv is None: # if the condition that makes the denominator infinite does not # make the original expression True then False can be returned l, r = clear_coefficients(d, S.Infinity) args = [_.subs(l, r) for _ in (lhs, rhs)] if args != [lhs, rhs]: rv = fuzzy_bool(Eq(*args)) if rv is True: rv = None elif any(a.is_infinite for a in Add.make_args(n)): # (inf or nan)/x != 0 rv = S.false if rv is not None: return _sympify(rv) return Relational.__new__(cls, lhs, rhs, **options) @classmethod def _eval_relation(cls, lhs, rhs): return _sympify(lhs == rhs) def _eval_rewrite_as_Add(self, *args, **kwargs): """return Eq(L, R) as L - R. To control the evaluation of the result set pass `evaluate=True` to give L - R; if `evaluate=None` then terms in L and R will not cancel but they will be listed in canonical order; otherwise non-canonical args will be returned. Examples ======== >>> from sympy import Eq, Add >>> from sympy.abc import b, x >>> eq = Eq(x + b, x - b) >>> eq.rewrite(Add) 2*b >>> eq.rewrite(Add, evaluate=None).args (b, b, x, -x) >>> eq.rewrite(Add, evaluate=False).args (b, x, b, -x) """ L, R = args evaluate = kwargs.get('evaluate', True) if evaluate: # allow cancellation of args return L - R args = Add.make_args(L) + Add.make_args(-R) if evaluate is None: # no cancellation, but canonical return _unevaluated_Add(*args) # no cancellation, not canonical return Add._from_args(args) @property def binary_symbols(self): if S.true in self.args or S.false in self.args: if self.lhs.is_Symbol: return set([self.lhs]) elif self.rhs.is_Symbol: return set([self.rhs]) return set() def _eval_simplify(self, ratio, measure, rational, inverse): from sympy.solvers.solveset import linear_coeffs # standard simplify e = super(Equality, self)._eval_simplify( ratio, measure, rational, inverse) if not isinstance(e, Equality): return e free = self.free_symbols if len(free) == 1: try: x = free.pop() m, b = linear_coeffs( e.rewrite(Add, evaluate=False), x) if m.is_zero is False: enew = e.func(x, -b/m) else: enew = e.func(m*x, -b) if measure(enew) <= ratio*measure(e): e = enew except ValueError: pass return e.canonical Eq = Equality class Unequality(Relational): """An unequal relation between two objects. Represents that two objects are not equal. If they can be shown to be definitively equal, this will reduce to False; if definitively unequal, this will reduce to True. Otherwise, the relation is maintained as an Unequality object. Examples ======== >>> from sympy import Ne >>> from sympy.abc import x, y >>> Ne(y, x+x**2) Ne(y, x**2 + x) See Also ======== Equality Notes ===== This class is not the same as the != operator. The != operator tests for exact structural equality between two expressions; this class compares expressions mathematically. This class is effectively the inverse of Equality. As such, it uses the same algorithms, including any available `_eval_Eq` methods. """ rel_op = '!=' __slots__ = [] def __new__(cls, lhs, rhs, **options): lhs = _sympify(lhs) rhs = _sympify(rhs) evaluate = options.pop('evaluate', global_evaluate[0]) if evaluate: is_equal = Equality(lhs, rhs) if isinstance(is_equal, BooleanAtom): return ~is_equal return Relational.__new__(cls, lhs, rhs, **options) @classmethod def _eval_relation(cls, lhs, rhs): return _sympify(lhs != rhs) @property def binary_symbols(self): if S.true in self.args or S.false in self.args: if self.lhs.is_Symbol: return set([self.lhs]) elif self.rhs.is_Symbol: return set([self.rhs]) return set() def _eval_simplify(self, ratio, measure, rational, inverse): # simplify as an equality eq = Equality(*self.args)._eval_simplify( ratio, measure, rational, inverse) if isinstance(eq, Equality): # send back Ne with the new args return self.func(*eq.args) return ~eq # result of Ne is ~Eq Ne = Unequality class _Inequality(Relational): """Internal base class for all *Than types. Each subclass must implement _eval_relation to provide the method for comparing two real numbers. """ __slots__ = [] def __new__(cls, lhs, rhs, **options): lhs = _sympify(lhs) rhs = _sympify(rhs) evaluate = options.pop('evaluate', global_evaluate[0]) if evaluate: # First we invoke the appropriate inequality method of `lhs` # (e.g., `lhs.__lt__`). That method will try to reduce to # boolean or raise an exception. It may keep calling # superclasses until it reaches `Expr` (e.g., `Expr.__lt__`). # In some cases, `Expr` will just invoke us again (if neither it # nor a subclass was able to reduce to boolean or raise an # exception). In that case, it must call us with # `evaluate=False` to prevent infinite recursion. r = cls._eval_relation(lhs, rhs) if r is not None: return r # Note: not sure r could be None, perhaps we never take this # path? In principle, could use this to shortcut out if a # class realizes the inequality cannot be evaluated further. # make a "non-evaluated" Expr for the inequality return Relational.__new__(cls, lhs, rhs, **options) class _Greater(_Inequality): """Not intended for general use _Greater is only used so that GreaterThan and StrictGreaterThan may subclass it for the .gts and .lts properties. """ __slots__ = () @property def gts(self): return self._args[0] @property def lts(self): return self._args[1] class _Less(_Inequality): """Not intended for general use. _Less is only used so that LessThan and StrictLessThan may subclass it for the .gts and .lts properties. """ __slots__ = () @property def gts(self): return self._args[1] @property def lts(self): return self._args[0] class GreaterThan(_Greater): """Class representations of inequalities. Extended Summary ================ The ``*Than`` classes represent inequal relationships, where the left-hand side is generally bigger or smaller than the right-hand side. For example, the GreaterThan class represents an inequal relationship where the left-hand side is at least as big as the right side, if not bigger. In mathematical notation: lhs >= rhs In total, there are four ``*Than`` classes, to represent the four inequalities: +-----------------+--------+ |Class Name | Symbol | +=================+========+ |GreaterThan | (>=) | +-----------------+--------+ |LessThan | (<=) | +-----------------+--------+ |StrictGreaterThan| (>) | +-----------------+--------+ |StrictLessThan | (<) | +-----------------+--------+ All classes take two arguments, lhs and rhs. +----------------------------+-----------------+ |Signature Example | Math equivalent | +============================+=================+ |GreaterThan(lhs, rhs) | lhs >= rhs | +----------------------------+-----------------+ |LessThan(lhs, rhs) | lhs <= rhs | +----------------------------+-----------------+ |StrictGreaterThan(lhs, rhs) | lhs > rhs | +----------------------------+-----------------+ |StrictLessThan(lhs, rhs) | lhs < rhs | +----------------------------+-----------------+ In addition to the normal .lhs and .rhs of Relations, ``*Than`` inequality objects also have the .lts and .gts properties, which represent the "less than side" and "greater than side" of the operator. Use of .lts and .gts in an algorithm rather than .lhs and .rhs as an assumption of inequality direction will make more explicit the intent of a certain section of code, and will make it similarly more robust to client code changes: >>> from sympy import GreaterThan, StrictGreaterThan >>> from sympy import LessThan, StrictLessThan >>> from sympy import And, Ge, Gt, Le, Lt, Rel, S >>> from sympy.abc import x, y, z >>> from sympy.core.relational import Relational >>> e = GreaterThan(x, 1) >>> e x >= 1 >>> '%s >= %s is the same as %s <= %s' % (e.gts, e.lts, e.lts, e.gts) 'x >= 1 is the same as 1 <= x' Examples ======== One generally does not instantiate these classes directly, but uses various convenience methods: >>> for f in [Ge, Gt, Le, Lt]: # convenience wrappers ... print(f(x, 2)) x >= 2 x > 2 x <= 2 x < 2 Another option is to use the Python inequality operators (>=, >, <=, <) directly. Their main advantage over the Ge, Gt, Le, and Lt counterparts, is that one can write a more "mathematical looking" statement rather than littering the math with oddball function calls. However there are certain (minor) caveats of which to be aware (search for 'gotcha', below). >>> x >= 2 x >= 2 >>> _ == Ge(x, 2) True However, it is also perfectly valid to instantiate a ``*Than`` class less succinctly and less conveniently: >>> Rel(x, 1, ">") x > 1 >>> Relational(x, 1, ">") x > 1 >>> StrictGreaterThan(x, 1) x > 1 >>> GreaterThan(x, 1) x >= 1 >>> LessThan(x, 1) x <= 1 >>> StrictLessThan(x, 1) x < 1 Notes ===== There are a couple of "gotchas" to be aware of when using Python's operators. The first is that what your write is not always what you get: >>> 1 < x x > 1 Due to the order that Python parses a statement, it may not immediately find two objects comparable. When "1 < x" is evaluated, Python recognizes that the number 1 is a native number and that x is *not*. Because a native Python number does not know how to compare itself with a SymPy object Python will try the reflective operation, "x > 1" and that is the form that gets evaluated, hence returned. If the order of the statement is important (for visual output to the console, perhaps), one can work around this annoyance in a couple ways: (1) "sympify" the literal before comparison >>> S(1) < x 1 < x (2) use one of the wrappers or less succinct methods described above >>> Lt(1, x) 1 < x >>> Relational(1, x, "<") 1 < x The second gotcha involves writing equality tests between relationals when one or both sides of the test involve a literal relational: >>> e = x < 1; e x < 1 >>> e == e # neither side is a literal True >>> e == x < 1 # expecting True, too False >>> e != x < 1 # expecting False x < 1 >>> x < 1 != x < 1 # expecting False or the same thing as before Traceback (most recent call last): ... TypeError: cannot determine truth value of Relational The solution for this case is to wrap literal relationals in parentheses: >>> e == (x < 1) True >>> e != (x < 1) False >>> (x < 1) != (x < 1) False The third gotcha involves chained inequalities not involving '==' or '!='. Occasionally, one may be tempted to write: >>> e = x < y < z Traceback (most recent call last): ... TypeError: symbolic boolean expression has no truth value. Due to an implementation detail or decision of Python [1]_, there is no way for SymPy to create a chained inequality with that syntax so one must use And: >>> e = And(x < y, y < z) >>> type( e ) And >>> e (x < y) & (y < z) Although this can also be done with the '&' operator, it cannot be done with the 'and' operarator: >>> (x < y) & (y < z) (x < y) & (y < z) >>> (x < y) and (y < z) Traceback (most recent call last): ... TypeError: cannot determine truth value of Relational .. [1] This implementation detail is that Python provides no reliable method to determine that a chained inequality is being built. Chained comparison operators are evaluated pairwise, using "and" logic (see http://docs.python.org/2/reference/expressions.html#notin). This is done in an efficient way, so that each object being compared is only evaluated once and the comparison can short-circuit. For example, ``1 > 2 > 3`` is evaluated by Python as ``(1 > 2) and (2 > 3)``. The ``and`` operator coerces each side into a bool, returning the object itself when it short-circuits. The bool of the --Than operators will raise TypeError on purpose, because SymPy cannot determine the mathematical ordering of symbolic expressions. Thus, if we were to compute ``x > y > z``, with ``x``, ``y``, and ``z`` being Symbols, Python converts the statement (roughly) into these steps: (1) x > y > z (2) (x > y) and (y > z) (3) (GreaterThanObject) and (y > z) (4) (GreaterThanObject.__nonzero__()) and (y > z) (5) TypeError Because of the "and" added at step 2, the statement gets turned into a weak ternary statement, and the first object's __nonzero__ method will raise TypeError. Thus, creating a chained inequality is not possible. In Python, there is no way to override the ``and`` operator, or to control how it short circuits, so it is impossible to make something like ``x > y > z`` work. There was a PEP to change this, :pep:`335`, but it was officially closed in March, 2012. """ __slots__ = () rel_op = '>=' @classmethod def _eval_relation(cls, lhs, rhs): # We don't use the op symbol here: workaround issue #7951 return _sympify(lhs.__ge__(rhs)) Ge = GreaterThan class LessThan(_Less): __doc__ = GreaterThan.__doc__ __slots__ = () rel_op = '<=' @classmethod def _eval_relation(cls, lhs, rhs): # We don't use the op symbol here: workaround issue #7951 return _sympify(lhs.__le__(rhs)) Le = LessThan class StrictGreaterThan(_Greater): __doc__ = GreaterThan.__doc__ __slots__ = () rel_op = '>' @classmethod def _eval_relation(cls, lhs, rhs): # We don't use the op symbol here: workaround issue #7951 return _sympify(lhs.__gt__(rhs)) Gt = StrictGreaterThan class StrictLessThan(_Less): __doc__ = GreaterThan.__doc__ __slots__ = () rel_op = '<' @classmethod def _eval_relation(cls, lhs, rhs): # We don't use the op symbol here: workaround issue #7951 return _sympify(lhs.__lt__(rhs)) Lt = StrictLessThan # A class-specific (not object-specific) data item used for a minor speedup. It # is defined here, rather than directly in the class, because the classes that # it references have not been defined until now (e.g. StrictLessThan). Relational.ValidRelationOperator = { None: Equality, '==': Equality, 'eq': Equality, '!=': Unequality, '<>': Unequality, 'ne': Unequality, '>=': GreaterThan, 'ge': GreaterThan, '<=': LessThan, 'le': LessThan, '>': StrictGreaterThan, 'gt': StrictGreaterThan, '<': StrictLessThan, 'lt': StrictLessThan, }

3dc576bece2df886560b06ad40e8d6e815c1d3d541c6a49e3307b9b481025ee3

from __future__ import print_function, division import decimal import fractions import math import re as regex from .containers import Tuple from .sympify import converter, sympify, _sympify, SympifyError, _convert_numpy_types from .singleton import S, Singleton from .expr import Expr, AtomicExpr from .decorators import _sympifyit from .cache import cacheit, clear_cache from .logic import fuzzy_not from sympy.core.compatibility import ( as_int, integer_types, long, string_types, with_metaclass, HAS_GMPY, SYMPY_INTS, int_info) from sympy.core.cache import lru_cache import mpmath import mpmath.libmp as mlib from mpmath.libmp.backend import MPZ from mpmath.libmp import mpf_pow, mpf_pi, mpf_e, phi_fixed from mpmath.ctx_mp import mpnumeric from mpmath.libmp.libmpf import ( finf as _mpf_inf, fninf as _mpf_ninf, fnan as _mpf_nan, fzero as _mpf_zero, _normalize as mpf_normalize, prec_to_dps) from sympy.utilities.misc import debug, filldedent from .evaluate import global_evaluate from sympy.utilities.exceptions import SymPyDeprecationWarning rnd = mlib.round_nearest _LOG2 = math.log(2) def comp(z1, z2, tol=None): """Return a bool indicating whether the error between z1 and z2 is <= tol. If ``tol`` is None then True will be returned if there is a significant difference between the numbers: ``abs(z1 - z2)*10**p <= 1/2`` where ``p`` is the lower of the precisions of the values. A comparison of strings will be made if ``z1`` is a Number and a) ``z2`` is a string or b) ``tol`` is '' and ``z2`` is a Number. When ``tol`` is a nonzero value, if z2 is non-zero and ``|z1| > 1`` the error is normalized by ``|z1|``, so if you want to see if the absolute error between ``z1`` and ``z2`` is <= ``tol`` then call this as ``comp(z1 - z2, 0, tol)``. """ if type(z2) is str: if not isinstance(z1, Number): raise ValueError('when z2 is a str z1 must be a Number') return str(z1) == z2 if not z1: z1, z2 = z2, z1 if not z1: return True if not tol: if tol is None: if type(z2) is str and getattr(z1, 'is_Number', False): return str(z1) == z2 a, b = Float(z1), Float(z2) return int(abs(a - b)*10**prec_to_dps( min(a._prec, b._prec)))*2 <= 1 elif all(getattr(i, 'is_Number', False) for i in (z1, z2)): return z1._prec == z2._prec and str(z1) == str(z2) raise ValueError('exact comparison requires two Numbers') diff = abs(z1 - z2) az1 = abs(z1) if z2 and az1 > 1: return diff/az1 <= tol else: return diff <= tol def mpf_norm(mpf, prec): """Return the mpf tuple normalized appropriately for the indicated precision after doing a check to see if zero should be returned or not when the mantissa is 0. ``mpf_normlize`` always assumes that this is zero, but it may not be since the mantissa for mpf's values "+inf", "-inf" and "nan" have a mantissa of zero, too. Note: this is not intended to validate a given mpf tuple, so sending mpf tuples that were not created by mpmath may produce bad results. This is only a wrapper to ``mpf_normalize`` which provides the check for non- zero mpfs that have a 0 for the mantissa. """ sign, man, expt, bc = mpf if not man: # hack for mpf_normalize which does not do this; # it assumes that if man is zero the result is 0 # (see issue 6639) if not bc: return _mpf_zero else: # don't change anything; this should already # be a well formed mpf tuple return mpf # Necessary if mpmath is using the gmpy backend from mpmath.libmp.backend import MPZ rv = mpf_normalize(sign, MPZ(man), expt, bc, prec, rnd) return rv # TODO: we should use the warnings module _errdict = {"divide": False} def seterr(divide=False): """ Should sympy raise an exception on 0/0 or return a nan? divide == True .... raise an exception divide == False ... return nan """ if _errdict["divide"] != divide: clear_cache() _errdict["divide"] = divide def _as_integer_ratio(p): neg_pow, man, expt, bc = getattr(p, '_mpf_', mpmath.mpf(p)._mpf_) p = [1, -1][neg_pow % 2]*man if expt < 0: q = 2**-expt else: q = 1 p *= 2**expt return int(p), int(q) def _decimal_to_Rational_prec(dec): """Convert an ordinary decimal instance to a Rational.""" if not dec.is_finite(): raise TypeError("dec must be finite, got %s." % dec) s, d, e = dec.as_tuple() prec = len(d) if e >= 0: # it's an integer rv = Integer(int(dec)) else: s = (-1)**s d = sum([di*10**i for i, di in enumerate(reversed(d))]) rv = Rational(s*d, 10**-e) return rv, prec def _literal_float(f): """Return True if n can be interpreted as a floating point number.""" pat = r"[-+]?((\d*\.\d+)|(\d+\.?))(eE[-+]?\d+)?" return bool(regex.match(pat, f)) # (a,b) -> gcd(a,b) # TODO caching with decorator, but not to degrade performance @lru_cache(1024) def igcd(*args): """Computes nonnegative integer greatest common divisor. The algorithm is based on the well known Euclid's algorithm. To improve speed, igcd() has its own caching mechanism implemented. Examples ======== >>> from sympy.core.numbers import igcd >>> igcd(2, 4) 2 >>> igcd(5, 10, 15) 5 """ if len(args) < 2: raise TypeError( 'igcd() takes at least 2 arguments (%s given)' % len(args)) args_temp = [abs(as_int(i)) for i in args] if 1 in args_temp: return 1 a = args_temp.pop() for b in args_temp: a = igcd2(a, b) if b else a return a try: from math import gcd as igcd2 except ImportError: def igcd2(a, b): """Compute gcd of two Python integers a and b.""" if (a.bit_length() > BIGBITS and b.bit_length() > BIGBITS): return igcd_lehmer(a, b) a, b = abs(a), abs(b) while b: a, b = b, a % b return a # Use Lehmer's algorithm only for very large numbers. # The limit could be different on Python 2.7 and 3.x. # If so, then this could be defined in compatibility.py. BIGBITS = 5000 def igcd_lehmer(a, b): """Computes greatest common divisor of two integers. Euclid's algorithm for the computation of the greatest common divisor gcd(a, b) of two (positive) integers a and b is based on the division identity a = q*b + r, where the quotient q and the remainder r are integers and 0 <= r < b. Then each common divisor of a and b divides r, and it follows that gcd(a, b) == gcd(b, r). The algorithm works by constructing the sequence r0, r1, r2, ..., where r0 = a, r1 = b, and each rn is the remainder from the division of the two preceding elements. In Python, q = a // b and r = a % b are obtained by the floor division and the remainder operations, respectively. These are the most expensive arithmetic operations, especially for large a and b. Lehmer's algorithm is based on the observation that the quotients qn = r(n-1) // rn are in general small integers even when a and b are very large. Hence the quotients can be usually determined from a relatively small number of most significant bits. The efficiency of the algorithm is further enhanced by not computing each long remainder in Euclid's sequence. The remainders are linear combinations of a and b with integer coefficients derived from the quotients. The coefficients can be computed as far as the quotients can be determined from the chosen most significant parts of a and b. Only then a new pair of consecutive remainders is computed and the algorithm starts anew with this pair. References ========== .. [1] https://en.wikipedia.org/wiki/Lehmer%27s_GCD_algorithm """ a, b = abs(as_int(a)), abs(as_int(b)) if a < b: a, b = b, a # The algorithm works by using one or two digit division # whenever possible. The outer loop will replace the # pair (a, b) with a pair of shorter consecutive elements # of the Euclidean gcd sequence until a and b # fit into two Python (long) int digits. nbits = 2*int_info.bits_per_digit while a.bit_length() > nbits and b != 0: # Quotients are mostly small integers that can # be determined from most significant bits. n = a.bit_length() - nbits x, y = int(a >> n), int(b >> n) # most significant bits # Elements of the Euclidean gcd sequence are linear # combinations of a and b with integer coefficients. # Compute the coefficients of consecutive pairs # a' = A*a + B*b, b' = C*a + D*b # using small integer arithmetic as far as possible. A, B, C, D = 1, 0, 0, 1 # initial values while True: # The coefficients alternate in sign while looping. # The inner loop combines two steps to keep track # of the signs. # At this point we have # A > 0, B <= 0, C <= 0, D > 0, # x' = x + B <= x < x" = x + A, # y' = y + C <= y < y" = y + D, # and # x'*N <= a' < x"*N, y'*N <= b' < y"*N, # where N = 2**n. # Now, if y' > 0, and x"//y' and x'//y" agree, # then their common value is equal to q = a'//b'. # In addition, # x'%y" = x' - q*y" < x" - q*y' = x"%y', # and # (x'%y")*N < a'%b' < (x"%y')*N. # On the other hand, we also have x//y == q, # and therefore # x'%y" = x + B - q*(y + D) = x%y + B', # x"%y' = x + A - q*(y + C) = x%y + A', # where # B' = B - q*D < 0, A' = A - q*C > 0. if y + C <= 0: break q = (x + A) // (y + C) # Now x'//y" <= q, and equality holds if # x' - q*y" = (x - q*y) + (B - q*D) >= 0. # This is a minor optimization to avoid division. x_qy, B_qD = x - q*y, B - q*D if x_qy + B_qD < 0: break # Next step in the Euclidean sequence. x, y = y, x_qy A, B, C, D = C, D, A - q*C, B_qD # At this point the signs of the coefficients # change and their roles are interchanged. # A <= 0, B > 0, C > 0, D < 0, # x' = x + A <= x < x" = x + B, # y' = y + D < y < y" = y + C. if y + D <= 0: break q = (x + B) // (y + D) x_qy, A_qC = x - q*y, A - q*C if x_qy + A_qC < 0: break x, y = y, x_qy A, B, C, D = C, D, A_qC, B - q*D # Now the conditions on top of the loop # are again satisfied. # A > 0, B < 0, C < 0, D > 0. if B == 0: # This can only happen when y == 0 in the beginning # and the inner loop does nothing. # Long division is forced. a, b = b, a % b continue # Compute new long arguments using the coefficients. a, b = A*a + B*b, C*a + D*b # Small divisors. Finish with the standard algorithm. while b: a, b = b, a % b return a def ilcm(*args): """Computes integer least common multiple. Examples ======== >>> from sympy.core.numbers import ilcm >>> ilcm(5, 10) 10 >>> ilcm(7, 3) 21 >>> ilcm(5, 10, 15) 30 """ if len(args) < 2: raise TypeError( 'ilcm() takes at least 2 arguments (%s given)' % len(args)) if 0 in args: return 0 a = args[0] for b in args[1:]: a = a // igcd(a, b) * b # since gcd(a,b) | a return a def igcdex(a, b): """Returns x, y, g such that g = x*a + y*b = gcd(a, b). >>> from sympy.core.numbers import igcdex >>> igcdex(2, 3) (-1, 1, 1) >>> igcdex(10, 12) (-1, 1, 2) >>> x, y, g = igcdex(100, 2004) >>> x, y, g (-20, 1, 4) >>> x*100 + y*2004 4 """ if (not a) and (not b): return (0, 1, 0) if not a: return (0, b//abs(b), abs(b)) if not b: return (a//abs(a), 0, abs(a)) if a < 0: a, x_sign = -a, -1 else: x_sign = 1 if b < 0: b, y_sign = -b, -1 else: y_sign = 1 x, y, r, s = 1, 0, 0, 1 while b: (c, q) = (a % b, a // b) (a, b, r, s, x, y) = (b, c, x - q*r, y - q*s, r, s) return (x*x_sign, y*y_sign, a) def mod_inverse(a, m): """ Return the number c such that, (a * c) = 1 (mod m) where c has the same sign as m. If no such value exists, a ValueError is raised. Examples ======== >>> from sympy import S >>> from sympy.core.numbers import mod_inverse Suppose we wish to find multiplicative inverse x of 3 modulo 11. This is the same as finding x such that 3 * x = 1 (mod 11). One value of x that satisfies this congruence is 4. Because 3 * 4 = 12 and 12 = 1 (mod 11). This is the value return by mod_inverse: >>> mod_inverse(3, 11) 4 >>> mod_inverse(-3, 11) 7 When there is a common factor between the numerators of ``a`` and ``m`` the inverse does not exist: >>> mod_inverse(2, 4) Traceback (most recent call last): ... ValueError: inverse of 2 mod 4 does not exist >>> mod_inverse(S(2)/7, S(5)/2) 7/2 References ========== - https://en.wikipedia.org/wiki/Modular_multiplicative_inverse - https://en.wikipedia.org/wiki/Extended_Euclidean_algorithm """ c = None try: a, m = as_int(a), as_int(m) if m != 1 and m != -1: x, y, g = igcdex(a, m) if g == 1: c = x % m except ValueError: a, m = sympify(a), sympify(m) if not (a.is_number and m.is_number): raise TypeError(filldedent(''' Expected numbers for arguments; symbolic `mod_inverse` is not implemented but symbolic expressions can be handled with the similar function, sympy.polys.polytools.invert''')) big = (m > 1) if not (big is S.true or big is S.false): raise ValueError('m > 1 did not evaluate; try to simplify %s' % m) elif big: c = 1/a if c is None: raise ValueError('inverse of %s (mod %s) does not exist' % (a, m)) return c class Number(AtomicExpr): """Represents atomic numbers in SymPy. Floating point numbers are represented by the Float class. Rational numbers (of any size) are represented by the Rational class. Integer numbers (of any size) are represented by the Integer class. Float and Rational are subclasses of Number; Integer is a subclass of Rational. For example, ``2/3`` is represented as ``Rational(2, 3)`` which is a different object from the floating point number obtained with Python division ``2/3``. Even for numbers that are exactly represented in binary, there is a difference between how two forms, such as ``Rational(1, 2)`` and ``Float(0.5)``, are used in SymPy. The rational form is to be preferred in symbolic computations. Other kinds of numbers, such as algebraic numbers ``sqrt(2)`` or complex numbers ``3 + 4*I``, are not instances of Number class as they are not atomic. See Also ======== Float, Integer, Rational """ is_commutative = True is_number = True is_Number = True __slots__ = [] # Used to make max(x._prec, y._prec) return x._prec when only x is a float _prec = -1 def __new__(cls, *obj): if len(obj) == 1: obj = obj[0] if isinstance(obj, Number): return obj if isinstance(obj, SYMPY_INTS): return Integer(obj) if isinstance(obj, tuple) and len(obj) == 2: return Rational(*obj) if isinstance(obj, (float, mpmath.mpf, decimal.Decimal)): return Float(obj) if isinstance(obj, string_types): val = sympify(obj) if isinstance(val, Number): return val else: raise ValueError('String "%s" does not denote a Number' % obj) msg = "expected str|int|long|float|Decimal|Number object but got %r" raise TypeError(msg % type(obj).__name__) def invert(self, other, *gens, **args): from sympy.polys.polytools import invert if getattr(other, 'is_number', True): return mod_inverse(self, other) return invert(self, other, *gens, **args) def __divmod__(self, other): from .containers import Tuple try: other = Number(other) except TypeError: msg = "unsupported operand type(s) for divmod(): '%s' and '%s'" raise TypeError(msg % (type(self).__name__, type(other).__name__)) if not other: raise ZeroDivisionError('modulo by zero') if self.is_Integer and other.is_Integer: return Tuple(*divmod(self.p, other.p)) else: rat = self/other w = int(rat) if rat > 0 else int(rat) - 1 r = self - other*w return Tuple(w, r) def __rdivmod__(self, other): try: other = Number(other) except TypeError: msg = "unsupported operand type(s) for divmod(): '%s' and '%s'" raise TypeError(msg % (type(other).__name__, type(self).__name__)) return divmod(other, self) def __round__(self, *args): return round(float(self), *args) def _as_mpf_val(self, prec): """Evaluation of mpf tuple accurate to at least prec bits.""" raise NotImplementedError('%s needs ._as_mpf_val() method' % (self.__class__.__name__)) def _eval_evalf(self, prec): return Float._new(self._as_mpf_val(prec), prec) def _as_mpf_op(self, prec): prec = max(prec, self._prec) return self._as_mpf_val(prec), prec def __float__(self): return mlib.to_float(self._as_mpf_val(53)) def floor(self): raise NotImplementedError('%s needs .floor() method' % (self.__class__.__name__)) def ceiling(self): raise NotImplementedError('%s needs .ceiling() method' % (self.__class__.__name__)) def _eval_conjugate(self): return self def _eval_order(self, *symbols): from sympy import Order # Order(5, x, y) -> Order(1,x,y) return Order(S.One, *symbols) def _eval_subs(self, old, new): if old == -self: return -new return self # there is no other possibility def _eval_is_finite(self): return True @classmethod def class_key(cls): return 1, 0, 'Number' @cacheit def sort_key(self, order=None): return self.class_key(), (0, ()), (), self @_sympifyit('other', NotImplemented) def __add__(self, other): if isinstance(other, Number) and global_evaluate[0]: if other is S.NaN: return S.NaN elif other is S.Infinity: return S.Infinity elif other is S.NegativeInfinity: return S.NegativeInfinity return AtomicExpr.__add__(self, other) @_sympifyit('other', NotImplemented) def __sub__(self, other): if isinstance(other, Number) and global_evaluate[0]: if other is S.NaN: return S.NaN elif other is S.Infinity: return S.NegativeInfinity elif other is S.NegativeInfinity: return S.Infinity return AtomicExpr.__sub__(self, other) @_sympifyit('other', NotImplemented) def __mul__(self, other): if isinstance(other, Number) and global_evaluate[0]: if other is S.NaN: return S.NaN elif other is S.Infinity: if self.is_zero: return S.NaN elif self.is_positive: return S.Infinity else: return S.NegativeInfinity elif other is S.NegativeInfinity: if self.is_zero: return S.NaN elif self.is_positive: return S.NegativeInfinity else: return S.Infinity elif isinstance(other, Tuple): return NotImplemented return AtomicExpr.__mul__(self, other) @_sympifyit('other', NotImplemented) def __div__(self, other): if isinstance(other, Number) and global_evaluate[0]: if other is S.NaN: return S.NaN elif other is S.Infinity or other is S.NegativeInfinity: return S.Zero return AtomicExpr.__div__(self, other) __truediv__ = __div__ def __eq__(self, other): raise NotImplementedError('%s needs .__eq__() method' % (self.__class__.__name__)) def __ne__(self, other): raise NotImplementedError('%s needs .__ne__() method' % (self.__class__.__name__)) def __lt__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s < %s" % (self, other)) raise NotImplementedError('%s needs .__lt__() method' % (self.__class__.__name__)) def __le__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s <= %s" % (self, other)) raise NotImplementedError('%s needs .__le__() method' % (self.__class__.__name__)) def __gt__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s > %s" % (self, other)) return _sympify(other).__lt__(self) def __ge__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s >= %s" % (self, other)) return _sympify(other).__le__(self) def __hash__(self): return super(Number, self).__hash__() def is_constant(self, *wrt, **flags): return True def as_coeff_mul(self, *deps, **kwargs): # a -> c*t if self.is_Rational or not kwargs.pop('rational', True): return self, tuple() elif self.is_negative: return S.NegativeOne, (-self,) return S.One, (self,) def as_coeff_add(self, *deps): # a -> c + t if self.is_Rational: return self, tuple() return S.Zero, (self,) def as_coeff_Mul(self, rational=False): """Efficiently extract the coefficient of a product. """ if rational and not self.is_Rational: return S.One, self return (self, S.One) if self else (S.One, self) def as_coeff_Add(self, rational=False): """Efficiently extract the coefficient of a summation. """ if not rational: return self, S.Zero return S.Zero, self def gcd(self, other): """Compute GCD of `self` and `other`. """ from sympy.polys import gcd return gcd(self, other) def lcm(self, other): """Compute LCM of `self` and `other`. """ from sympy.polys import lcm return lcm(self, other) def cofactors(self, other): """Compute GCD and cofactors of `self` and `other`. """ from sympy.polys import cofactors return cofactors(self, other) class Float(Number): """Represent a floating-point number of arbitrary precision. Examples ======== >>> from sympy import Float >>> Float(3.5) 3.50000000000000 >>> Float(3) 3.00000000000000 Creating Floats from strings (and Python ``int`` and ``long`` types) will give a minimum precision of 15 digits, but the precision will automatically increase to capture all digits entered. >>> Float(1) 1.00000000000000 >>> Float(10**20) 100000000000000000000. >>> Float('1e20') 100000000000000000000. However, *floating-point* numbers (Python ``float`` types) retain only 15 digits of precision: >>> Float(1e20) 1.00000000000000e+20 >>> Float(1.23456789123456789) 1.23456789123457 It may be preferable to enter high-precision decimal numbers as strings: Float('1.23456789123456789') 1.23456789123456789 The desired number of digits can also be specified: >>> Float('1e-3', 3) 0.00100 >>> Float(100, 4) 100.0 Float can automatically count significant figures if a null string is sent for the precision; space are also allowed in the string. (Auto- counting is only allowed for strings, ints and longs). >>> Float('123 456 789 . 123 456', '') 123456789.123456 >>> Float('12e-3', '') 0.012 >>> Float(3, '') 3. If a number is written in scientific notation, only the digits before the exponent are considered significant if a decimal appears, otherwise the "e" signifies only how to move the decimal: >>> Float('60.e2', '') # 2 digits significant 6.0e+3 >>> Float('60e2', '') # 4 digits significant 6000. >>> Float('600e-2', '') # 3 digits significant 6.00 Notes ===== Floats are inexact by their nature unless their value is a binary-exact value. >>> approx, exact = Float(.1, 1), Float(.125, 1) For calculation purposes, evalf needs to be able to change the precision but this will not increase the accuracy of the inexact value. The following is the most accurate 5-digit approximation of a value of 0.1 that had only 1 digit of precision: >>> approx.evalf(5) 0.099609 By contrast, 0.125 is exact in binary (as it is in base 10) and so it can be passed to Float or evalf to obtain an arbitrary precision with matching accuracy: >>> Float(exact, 5) 0.12500 >>> exact.evalf(20) 0.12500000000000000000 Trying to make a high-precision Float from a float is not disallowed, but one must keep in mind that the *underlying float* (not the apparent decimal value) is being obtained with high precision. For example, 0.3 does not have a finite binary representation. The closest rational is the fraction 5404319552844595/2**54. So if you try to obtain a Float of 0.3 to 20 digits of precision you will not see the same thing as 0.3 followed by 19 zeros: >>> Float(0.3, 20) 0.29999999999999998890 If you want a 20-digit value of the decimal 0.3 (not the floating point approximation of 0.3) you should send the 0.3 as a string. The underlying representation is still binary but a higher precision than Python's float is used: >>> Float('0.3', 20) 0.30000000000000000000 Although you can increase the precision of an existing Float using Float it will not increase the accuracy -- the underlying value is not changed: >>> def show(f): # binary rep of Float ... from sympy import Mul, Pow ... s, m, e, b = f._mpf_ ... v = Mul(int(m), Pow(2, int(e), evaluate=False), evaluate=False) ... print('%s at prec=%s' % (v, f._prec)) ... >>> t = Float('0.3', 3) >>> show(t) 4915/2**14 at prec=13 >>> show(Float(t, 20)) # higher prec, not higher accuracy 4915/2**14 at prec=70 >>> show(Float(t, 2)) # lower prec 307/2**10 at prec=10 The same thing happens when evalf is used on a Float: >>> show(t.evalf(20)) 4915/2**14 at prec=70 >>> show(t.evalf(2)) 307/2**10 at prec=10 Finally, Floats can be instantiated with an mpf tuple (n, c, p) to produce the number (-1)**n*c*2**p: >>> n, c, p = 1, 5, 0 >>> (-1)**n*c*2**p -5 >>> Float((1, 5, 0)) -5.00000000000000 An actual mpf tuple also contains the number of bits in c as the last element of the tuple: >>> _._mpf_ (1, 5, 0, 3) This is not needed for instantiation and is not the same thing as the precision. The mpf tuple and the precision are two separate quantities that Float tracks. """ __slots__ = ['_mpf_', '_prec'] # A Float represents many real numbers, # both rational and irrational. is_rational = None is_irrational = None is_number = True is_real = True is_Float = True def __new__(cls, num, dps=None, prec=None, precision=None): if prec is not None: SymPyDeprecationWarning( feature="Using 'prec=XX' to denote decimal precision", useinstead="'dps=XX' for decimal precision and 'precision=XX' "\ "for binary precision", issue=12820, deprecated_since_version="1.1").warn() dps = prec del prec # avoid using this deprecated kwarg if dps is not None and precision is not None: raise ValueError('Both decimal and binary precision supplied. ' 'Supply only one. ') if isinstance(num, string_types): num = num.replace(' ', '') if num.startswith('.') and len(num) > 1: num = '0' + num elif num.startswith('-.') and len(num) > 2: num = '-0.' + num[2:] elif isinstance(num, float) and num == 0: num = '0' elif isinstance(num, (SYMPY_INTS, Integer)): num = str(num) # faster than mlib.from_int elif num is S.Infinity: num = '+inf' elif num is S.NegativeInfinity: num = '-inf' elif type(num).__module__ == 'numpy': # support for numpy datatypes num = _convert_numpy_types(num) elif isinstance(num, mpmath.mpf): if precision is None: if dps is None: precision = num.context.prec num = num._mpf_ if dps is None and precision is None: dps = 15 if isinstance(num, Float): return num if isinstance(num, string_types) and _literal_float(num): try: Num = decimal.Decimal(num) except decimal.InvalidOperation: pass else: isint = '.' not in num num, dps = _decimal_to_Rational_prec(Num) if num.is_Integer and isint: dps = max(dps, len(str(num).lstrip('-'))) dps = max(15, dps) precision = mlib.libmpf.dps_to_prec(dps) elif precision == '' and dps is None or precision is None and dps == '': if not isinstance(num, string_types): raise ValueError('The null string can only be used when ' 'the number to Float is passed as a string or an integer.') ok = None if _literal_float(num): try: Num = decimal.Decimal(num) except decimal.InvalidOperation: pass else: isint = '.' not in num num, dps = _decimal_to_Rational_prec(Num) if num.is_Integer and isint: dps = max(dps, len(str(num).lstrip('-'))) precision = mlib.libmpf.dps_to_prec(dps) ok = True if ok is None: raise ValueError('string-float not recognized: %s' % num) # decimal precision(dps) is set and maybe binary precision(precision) # as well.From here on binary precision is used to compute the Float. # Hence, if supplied use binary precision else translate from decimal # precision. if precision is None or precision == '': precision = mlib.libmpf.dps_to_prec(dps) precision = int(precision) if isinstance(num, float): _mpf_ = mlib.from_float(num, precision, rnd) elif isinstance(num, string_types): _mpf_ = mlib.from_str(num, precision, rnd) elif isinstance(num, decimal.Decimal): if num.is_finite(): _mpf_ = mlib.from_str(str(num), precision, rnd) elif num.is_nan(): _mpf_ = _mpf_nan elif num.is_infinite(): if num > 0: _mpf_ = _mpf_inf else: _mpf_ = _mpf_ninf else: raise ValueError("unexpected decimal value %s" % str(num)) elif isinstance(num, tuple) and len(num) in (3, 4): if type(num[1]) is str: # it's a hexadecimal (coming from a pickled object) # assume that it is in standard form num = list(num) # If we're loading an object pickled in Python 2 into # Python 3, we may need to strip a tailing 'L' because # of a shim for int on Python 3, see issue #13470. if num[1].endswith('L'): num[1] = num[1][:-1] num[1] = MPZ(num[1], 16) _mpf_ = tuple(num) else: if len(num) == 4: # handle normalization hack return Float._new(num, precision) else: return (S.NegativeOne**num[0]*num[1]*S(2)**num[2]).evalf(precision) else: try: _mpf_ = num._as_mpf_val(precision) except (NotImplementedError, AttributeError): _mpf_ = mpmath.mpf(num, prec=precision)._mpf_ # special cases if _mpf_ == _mpf_zero: pass # we want a Float elif _mpf_ == _mpf_nan: return S.NaN obj = Expr.__new__(cls) obj._mpf_ = _mpf_ obj._prec = precision return obj @classmethod def _new(cls, _mpf_, _prec): # special cases if _mpf_ == _mpf_zero: return S.Zero # XXX this is different from Float which gives 0.0 elif _mpf_ == _mpf_nan: return S.NaN obj = Expr.__new__(cls) obj._mpf_ = mpf_norm(_mpf_, _prec) # XXX: Should this be obj._prec = obj._mpf_[3]? obj._prec = _prec return obj # mpz can't be pickled def __getnewargs__(self): return (mlib.to_pickable(self._mpf_),) def __getstate__(self): return {'_prec': self._prec} def _hashable_content(self): return (self._mpf_, self._prec) def floor(self): return Integer(int(mlib.to_int( mlib.mpf_floor(self._mpf_, self._prec)))) def ceiling(self): return Integer(int(mlib.to_int( mlib.mpf_ceil(self._mpf_, self._prec)))) @property def num(self): return mpmath.mpf(self._mpf_) def _as_mpf_val(self, prec): rv = mpf_norm(self._mpf_, prec) if rv != self._mpf_ and self._prec == prec: debug(self._mpf_, rv) return rv def _as_mpf_op(self, prec): return self._mpf_, max(prec, self._prec) def _eval_is_finite(self): if self._mpf_ in (_mpf_inf, _mpf_ninf): return False return True def _eval_is_infinite(self): if self._mpf_ in (_mpf_inf, _mpf_ninf): return True return False def _eval_is_integer(self): return self._mpf_ == _mpf_zero def _eval_is_negative(self): if self._mpf_ == _mpf_ninf: return True if self._mpf_ == _mpf_inf: return False return self.num < 0 def _eval_is_positive(self): if self._mpf_ == _mpf_inf: return True if self._mpf_ == _mpf_ninf: return False return self.num > 0 def _eval_is_zero(self): return self._mpf_ == _mpf_zero def __nonzero__(self): return self._mpf_ != _mpf_zero __bool__ = __nonzero__ def __neg__(self): return Float._new(mlib.mpf_neg(self._mpf_), self._prec) @_sympifyit('other', NotImplemented) def __add__(self, other): if isinstance(other, Number) and global_evaluate[0]: rhs, prec = other._as_mpf_op(self._prec) return Float._new(mlib.mpf_add(self._mpf_, rhs, prec, rnd), prec) return Number.__add__(self, other) @_sympifyit('other', NotImplemented) def __sub__(self, other): if isinstance(other, Number) and global_evaluate[0]: rhs, prec = other._as_mpf_op(self._prec) return Float._new(mlib.mpf_sub(self._mpf_, rhs, prec, rnd), prec) return Number.__sub__(self, other) @_sympifyit('other', NotImplemented) def __mul__(self, other): if isinstance(other, Number) and global_evaluate[0]: rhs, prec = other._as_mpf_op(self._prec) return Float._new(mlib.mpf_mul(self._mpf_, rhs, prec, rnd), prec) return Number.__mul__(self, other) @_sympifyit('other', NotImplemented) def __div__(self, other): if isinstance(other, Number) and other != 0 and global_evaluate[0]: rhs, prec = other._as_mpf_op(self._prec) return Float._new(mlib.mpf_div(self._mpf_, rhs, prec, rnd), prec) return Number.__div__(self, other) __truediv__ = __div__ @_sympifyit('other', NotImplemented) def __mod__(self, other): if isinstance(other, Rational) and other.q != 1 and global_evaluate[0]: # calculate mod with Rationals, *then* round the result return Float(Rational.__mod__(Rational(self), other), precision=self._prec) if isinstance(other, Float) and global_evaluate[0]: r = self/other if r == int(r): return Float(0, precision=max(self._prec, other._prec)) if isinstance(other, Number) and global_evaluate[0]: rhs, prec = other._as_mpf_op(self._prec) return Float._new(mlib.mpf_mod(self._mpf_, rhs, prec, rnd), prec) return Number.__mod__(self, other) @_sympifyit('other', NotImplemented) def __rmod__(self, other): if isinstance(other, Float) and global_evaluate[0]: return other.__mod__(self) if isinstance(other, Number) and global_evaluate[0]: rhs, prec = other._as_mpf_op(self._prec) return Float._new(mlib.mpf_mod(rhs, self._mpf_, prec, rnd), prec) return Number.__rmod__(self, other) def _eval_power(self, expt): """ expt is symbolic object but not equal to 0, 1 (-p)**r -> exp(r*log(-p)) -> exp(r*(log(p) + I*Pi)) -> -> p**r*(sin(Pi*r) + cos(Pi*r)*I) """ if self == 0: if expt.is_positive: return S.Zero if expt.is_negative: return Float('inf') if isinstance(expt, Number): if isinstance(expt, Integer): prec = self._prec return Float._new( mlib.mpf_pow_int(self._mpf_, expt.p, prec, rnd), prec) elif isinstance(expt, Rational) and \ expt.p == 1 and expt.q % 2 and self.is_negative: return Pow(S.NegativeOne, expt, evaluate=False)*( -self)._eval_power(expt) expt, prec = expt._as_mpf_op(self._prec) mpfself = self._mpf_ try: y = mpf_pow(mpfself, expt, prec, rnd) return Float._new(y, prec) except mlib.ComplexResult: re, im = mlib.mpc_pow( (mpfself, _mpf_zero), (expt, _mpf_zero), prec, rnd) return Float._new(re, prec) + \ Float._new(im, prec)*S.ImaginaryUnit def __abs__(self): return Float._new(mlib.mpf_abs(self._mpf_), self._prec) def __int__(self): if self._mpf_ == _mpf_zero: return 0 return int(mlib.to_int(self._mpf_)) # uses round_fast = round_down __long__ = __int__ def __eq__(self, other): if isinstance(other, float): # coerce to Float at same precision o = Float(other) try: ompf = o._as_mpf_val(self._prec) except ValueError: return False return bool(mlib.mpf_eq(self._mpf_, ompf)) try: other = _sympify(other) except SympifyError: return NotImplemented if other.is_NumberSymbol: if other.is_irrational: return False return other.__eq__(self) if other.is_Float: return bool(mlib.mpf_eq(self._mpf_, other._mpf_)) if other.is_Number: # numbers should compare at the same precision; # all _as_mpf_val routines should be sure to abide # by the request to change the prec if necessary; if # they don't, the equality test will fail since it compares # the mpf tuples ompf = other._as_mpf_val(self._prec) return bool(mlib.mpf_eq(self._mpf_, ompf)) return False # Float != non-Number def __ne__(self, other): return not self == other def __gt__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s > %s" % (self, other)) if other.is_NumberSymbol: return other.__lt__(self) if other.is_Rational and not other.is_Integer: self *= other.q other = _sympify(other.p) elif other.is_comparable: other = other.evalf() if other.is_Number and other is not S.NaN: return _sympify(bool( mlib.mpf_gt(self._mpf_, other._as_mpf_val(self._prec)))) return Expr.__gt__(self, other) def __ge__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s >= %s" % (self, other)) if other.is_NumberSymbol: return other.__le__(self) if other.is_Rational and not other.is_Integer: self *= other.q other = _sympify(other.p) elif other.is_comparable: other = other.evalf() if other.is_Number and other is not S.NaN: return _sympify(bool( mlib.mpf_ge(self._mpf_, other._as_mpf_val(self._prec)))) return Expr.__ge__(self, other) def __lt__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s < %s" % (self, other)) if other.is_NumberSymbol: return other.__gt__(self) if other.is_Rational and not other.is_Integer: self *= other.q other = _sympify(other.p) elif other.is_comparable: other = other.evalf() if other.is_Number and other is not S.NaN: return _sympify(bool( mlib.mpf_lt(self._mpf_, other._as_mpf_val(self._prec)))) return Expr.__lt__(self, other) def __le__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s <= %s" % (self, other)) if other.is_NumberSymbol: return other.__ge__(self) if other.is_Rational and not other.is_Integer: self *= other.q other = _sympify(other.p) elif other.is_comparable: other = other.evalf() if other.is_Number and other is not S.NaN: return _sympify(bool( mlib.mpf_le(self._mpf_, other._as_mpf_val(self._prec)))) return Expr.__le__(self, other) def __hash__(self): return super(Float, self).__hash__() def epsilon_eq(self, other, epsilon="1e-15"): return abs(self - other) < Float(epsilon) def _sage_(self): import sage.all as sage return sage.RealNumber(str(self)) def __format__(self, format_spec): return format(decimal.Decimal(str(self)), format_spec) # Add sympify converters converter[float] = converter[decimal.Decimal] = Float # this is here to work nicely in Sage RealNumber = Float class Rational(Number): """Represents rational numbers (p/q) of any size. Examples ======== >>> from sympy import Rational, nsimplify, S, pi >>> Rational(1, 2) 1/2 Rational is unprejudiced in accepting input. If a float is passed, the underlying value of the binary representation will be returned: >>> Rational(.5) 1/2 >>> Rational(.2) 3602879701896397/18014398509481984 If the simpler representation of the float is desired then consider limiting the denominator to the desired value or convert the float to a string (which is roughly equivalent to limiting the denominator to 10**12): >>> Rational(str(.2)) 1/5 >>> Rational(.2).limit_denominator(10**12) 1/5 An arbitrarily precise Rational is obtained when a string literal is passed: >>> Rational("1.23") 123/100 >>> Rational('1e-2') 1/100 >>> Rational(".1") 1/10 >>> Rational('1e-2/3.2') 1/320 The conversion of other types of strings can be handled by the sympify() function, and conversion of floats to expressions or simple fractions can be handled with nsimplify: >>> S('.[3]') # repeating digits in brackets 1/3 >>> S('3**2/10') # general expressions 9/10 >>> nsimplify(.3) # numbers that have a simple form 3/10 But if the input does not reduce to a literal Rational, an error will be raised: >>> Rational(pi) Traceback (most recent call last): ... TypeError: invalid input: pi Low-level --------- Access numerator and denominator as .p and .q: >>> r = Rational(3, 4) >>> r 3/4 >>> r.p 3 >>> r.q 4 Note that p and q return integers (not SymPy Integers) so some care is needed when using them in expressions: >>> r.p/r.q 0.75 See Also ======== sympify, sympy.simplify.simplify.nsimplify """ is_real = True is_integer = False is_rational = True is_number = True __slots__ = ['p', 'q'] is_Rational = True @cacheit def __new__(cls, p, q=None, gcd=None): if q is None: if isinstance(p, Rational): return p if isinstance(p, SYMPY_INTS): pass else: if isinstance(p, (float, Float)): return Rational(*_as_integer_ratio(p)) if not isinstance(p, string_types): try: p = sympify(p) except (SympifyError, SyntaxError): pass # error will raise below else: if p.count('/') > 1: raise TypeError('invalid input: %s' % p) p = p.replace(' ', '') pq = p.rsplit('/', 1) if len(pq) == 2: p, q = pq fp = fractions.Fraction(p) fq = fractions.Fraction(q) p = fp/fq try: p = fractions.Fraction(p) except ValueError: pass # error will raise below else: return Rational(p.numerator, p.denominator, 1) if not isinstance(p, Rational): raise TypeError('invalid input: %s' % p) q = 1 gcd = 1 else: p = Rational(p) q = Rational(q) if isinstance(q, Rational): p *= q.q q = q.p if isinstance(p, Rational): q *= p.q p = p.p # p and q are now integers if q == 0: if p == 0: if _errdict["divide"]: raise ValueError("Indeterminate 0/0") else: return S.NaN return S.ComplexInfinity if q < 0: q = -q p = -p if not gcd: gcd = igcd(abs(p), q) if gcd > 1: p //= gcd q //= gcd if q == 1: return Integer(p) if p == 1 and q == 2: return S.Half obj = Expr.__new__(cls) obj.p = p obj.q = q return obj def limit_denominator(self, max_denominator=1000000): """Closest Rational to self with denominator at most max_denominator. >>> from sympy import Rational >>> Rational('3.141592653589793').limit_denominator(10) 22/7 >>> Rational('3.141592653589793').limit_denominator(100) 311/99 """ f = fractions.Fraction(self.p, self.q) return Rational(f.limit_denominator(fractions.Fraction(int(max_denominator)))) def __getnewargs__(self): return (self.p, self.q) def _hashable_content(self): return (self.p, self.q) def _eval_is_positive(self): return self.p > 0 def _eval_is_zero(self): return self.p == 0 def __neg__(self): return Rational(-self.p, self.q) @_sympifyit('other', NotImplemented) def __add__(self, other): if global_evaluate[0]: if isinstance(other, Integer): return Rational(self.p + self.q*other.p, self.q, 1) elif isinstance(other, Rational): #TODO: this can probably be optimized more return Rational(self.p*other.q + self.q*other.p, self.q*other.q) elif isinstance(other, Float): return other + self else: return Number.__add__(self, other) return Number.__add__(self, other) __radd__ = __add__ @_sympifyit('other', NotImplemented) def __sub__(self, other): if global_evaluate[0]: if isinstance(other, Integer): return Rational(self.p - self.q*other.p, self.q, 1) elif isinstance(other, Rational): return Rational(self.p*other.q - self.q*other.p, self.q*other.q) elif isinstance(other, Float): return -other + self else: return Number.__sub__(self, other) return Number.__sub__(self, other) @_sympifyit('other', NotImplemented) def __rsub__(self, other): if global_evaluate[0]: if isinstance(other, Integer): return Rational(self.q*other.p - self.p, self.q, 1) elif isinstance(other, Rational): return Rational(self.q*other.p - self.p*other.q, self.q*other.q) elif isinstance(other, Float): return -self + other else: return Number.__rsub__(self, other) return Number.__rsub__(self, other) @_sympifyit('other', NotImplemented) def __mul__(self, other): if global_evaluate[0]: if isinstance(other, Integer): return Rational(self.p*other.p, self.q, igcd(other.p, self.q)) elif isinstance(other, Rational): return Rational(self.p*other.p, self.q*other.q, igcd(self.p, other.q)*igcd(self.q, other.p)) elif isinstance(other, Float): return other*self else: return Number.__mul__(self, other) return Number.__mul__(self, other) __rmul__ = __mul__ @_sympifyit('other', NotImplemented) def __div__(self, other): if global_evaluate[0]: if isinstance(other, Integer): if self.p and other.p == S.Zero: return S.ComplexInfinity else: return Rational(self.p, self.q*other.p, igcd(self.p, other.p)) elif isinstance(other, Rational): return Rational(self.p*other.q, self.q*other.p, igcd(self.p, other.p)*igcd(self.q, other.q)) elif isinstance(other, Float): return self*(1/other) else: return Number.__div__(self, other) return Number.__div__(self, other) @_sympifyit('other', NotImplemented) def __rdiv__(self, other): if global_evaluate[0]: if isinstance(other, Integer): return Rational(other.p*self.q, self.p, igcd(self.p, other.p)) elif isinstance(other, Rational): return Rational(other.p*self.q, other.q*self.p, igcd(self.p, other.p)*igcd(self.q, other.q)) elif isinstance(other, Float): return other*(1/self) else: return Number.__rdiv__(self, other) return Number.__rdiv__(self, other) __truediv__ = __div__ @_sympifyit('other', NotImplemented) def __mod__(self, other): if global_evaluate[0]: if isinstance(other, Rational): n = (self.p*other.q) // (other.p*self.q) return Rational(self.p*other.q - n*other.p*self.q, self.q*other.q) if isinstance(other, Float): # calculate mod with Rationals, *then* round the answer return Float(self.__mod__(Rational(other)), precision=other._prec) return Number.__mod__(self, other) return Number.__mod__(self, other) @_sympifyit('other', NotImplemented) def __rmod__(self, other): if isinstance(other, Rational): return Rational.__mod__(other, self) return Number.__rmod__(self, other) def _eval_power(self, expt): if isinstance(expt, Number): if isinstance(expt, Float): return self._eval_evalf(expt._prec)**expt if expt.is_negative: # (3/4)**-2 -> (4/3)**2 ne = -expt if (ne is S.One): return Rational(self.q, self.p) if self.is_negative: return S.NegativeOne**expt*Rational(self.q, -self.p)**ne else: return Rational(self.q, self.p)**ne if expt is S.Infinity: # -oo already caught by test for negative if self.p > self.q: # (3/2)**oo -> oo return S.Infinity if self.p < -self.q: # (-3/2)**oo -> oo + I*oo return S.Infinity + S.Infinity*S.ImaginaryUnit return S.Zero if isinstance(expt, Integer): # (4/3)**2 -> 4**2 / 3**2 return Rational(self.p**expt.p, self.q**expt.p, 1) if isinstance(expt, Rational): if self.p != 1: # (4/3)**(5/6) -> 4**(5/6)*3**(-5/6) return Integer(self.p)**expt*Integer(self.q)**(-expt) # as the above caught negative self.p, now self is positive return Integer(self.q)**Rational( expt.p*(expt.q - 1), expt.q) / \ Integer(self.q)**Integer(expt.p) if self.is_negative and expt.is_even: return (-self)**expt return def _as_mpf_val(self, prec): return mlib.from_rational(self.p, self.q, prec, rnd) def _mpmath_(self, prec, rnd): return mpmath.make_mpf(mlib.from_rational(self.p, self.q, prec, rnd)) def __abs__(self): return Rational(abs(self.p), self.q) def __int__(self): p, q = self.p, self.q if p < 0: return -int(-p//q) return int(p//q) __long__ = __int__ def floor(self): return Integer(self.p // self.q) def ceiling(self): return -Integer(-self.p // self.q) def __eq__(self, other): try: other = _sympify(other) except SympifyError: return NotImplemented if other.is_NumberSymbol: if other.is_irrational: return False return other.__eq__(self) if other.is_Number: if other.is_Rational: # a Rational is always in reduced form so will never be 2/4 # so we can just check equivalence of args return self.p == other.p and self.q == other.q if other.is_Float: return mlib.mpf_eq(self._as_mpf_val(other._prec), other._mpf_) return False def __ne__(self, other): return not self == other def __gt__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s > %s" % (self, other)) if other.is_NumberSymbol: return other.__lt__(self) expr = self if other.is_Number: if other.is_Rational: return _sympify(bool(self.p*other.q > self.q*other.p)) if other.is_Float: return _sympify(bool(mlib.mpf_gt( self._as_mpf_val(other._prec), other._mpf_))) elif other.is_number and other.is_real: expr, other = Integer(self.p), self.q*other return Expr.__gt__(expr, other) def __ge__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s >= %s" % (self, other)) if other.is_NumberSymbol: return other.__le__(self) expr = self if other.is_Number: if other.is_Rational: return _sympify(bool(self.p*other.q >= self.q*other.p)) if other.is_Float: return _sympify(bool(mlib.mpf_ge( self._as_mpf_val(other._prec), other._mpf_))) elif other.is_number and other.is_real: expr, other = Integer(self.p), self.q*other return Expr.__ge__(expr, other) def __lt__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s < %s" % (self, other)) if other.is_NumberSymbol: return other.__gt__(self) expr = self if other.is_Number: if other.is_Rational: return _sympify(bool(self.p*other.q < self.q*other.p)) if other.is_Float: return _sympify(bool(mlib.mpf_lt( self._as_mpf_val(other._prec), other._mpf_))) elif other.is_number and other.is_real: expr, other = Integer(self.p), self.q*other return Expr.__lt__(expr, other) def __le__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s <= %s" % (self, other)) expr = self if other.is_NumberSymbol: return other.__ge__(self) elif other.is_Number: if other.is_Rational: return _sympify(bool(self.p*other.q <= self.q*other.p)) if other.is_Float: return _sympify(bool(mlib.mpf_le( self._as_mpf_val(other._prec), other._mpf_))) elif other.is_number and other.is_real: expr, other = Integer(self.p), self.q*other return Expr.__le__(expr, other) def __hash__(self): return super(Rational, self).__hash__() def factors(self, limit=None, use_trial=True, use_rho=False, use_pm1=False, verbose=False, visual=False): """A wrapper to factorint which return factors of self that are smaller than limit (or cheap to compute). Special methods of factoring are disabled by default so that only trial division is used. """ from sympy.ntheory import factorrat return factorrat(self, limit=limit, use_trial=use_trial, use_rho=use_rho, use_pm1=use_pm1, verbose=verbose).copy() @_sympifyit('other', NotImplemented) def gcd(self, other): if isinstance(other, Rational): if other is S.Zero: return other return Rational( Integer(igcd(self.p, other.p)), Integer(ilcm(self.q, other.q))) return Number.gcd(self, other) @_sympifyit('other', NotImplemented) def lcm(self, other): if isinstance(other, Rational): return Rational( self.p // igcd(self.p, other.p) * other.p, igcd(self.q, other.q)) return Number.lcm(self, other) def as_numer_denom(self): return Integer(self.p), Integer(self.q) def _sage_(self): import sage.all as sage return sage.Integer(self.p)/sage.Integer(self.q) def as_content_primitive(self, radical=False, clear=True): """Return the tuple (R, self/R) where R is the positive Rational extracted from self. Examples ======== >>> from sympy import S >>> (S(-3)/2).as_content_primitive() (3/2, -1) See docstring of Expr.as_content_primitive for more examples. """ if self: if self.is_positive: return self, S.One return -self, S.NegativeOne return S.One, self def as_coeff_Mul(self, rational=False): """Efficiently extract the coefficient of a product. """ return self, S.One def as_coeff_Add(self, rational=False): """Efficiently extract the coefficient of a summation. """ return self, S.Zero # int -> Integer _intcache = {} # TODO move this tracing facility to sympy/core/trace.py ? def _intcache_printinfo(): ints = sorted(_intcache.keys()) nhit = _intcache_hits nmiss = _intcache_misses if nhit == 0 and nmiss == 0: print() print('Integer cache statistic was not collected') return miss_ratio = float(nmiss) / (nhit + nmiss) print() print('Integer cache statistic') print('-----------------------') print() print('#items: %i' % len(ints)) print() print(' #hit #miss #total') print() print('%5i %5i (%7.5f %%) %5i' % ( nhit, nmiss, miss_ratio*100, nhit + nmiss) ) print() print(ints) _intcache_hits = 0 _intcache_misses = 0 def int_trace(f): import os if os.getenv('SYMPY_TRACE_INT', 'no').lower() != 'yes': return f def Integer_tracer(cls, i): global _intcache_hits, _intcache_misses try: _intcache_hits += 1 return _intcache[i] except KeyError: _intcache_hits -= 1 _intcache_misses += 1 return f(cls, i) # also we want to hook our _intcache_printinfo into sys.atexit import atexit atexit.register(_intcache_printinfo) return Integer_tracer class Integer(Rational): """Represents integer numbers of any size. Examples ======== >>> from sympy import Integer >>> Integer(3) 3 If a float or a rational is passed to Integer, the fractional part will be discarded; the effect is of rounding toward zero. >>> Integer(3.8) 3 >>> Integer(-3.8) -3 A string is acceptable input if it can be parsed as an integer: >>> Integer("9" * 20) 99999999999999999999 It is rarely needed to explicitly instantiate an Integer, because Python integers are automatically converted to Integer when they are used in SymPy expressions. """ q = 1 is_integer = True is_number = True is_Integer = True __slots__ = ['p'] def _as_mpf_val(self, prec): return mlib.from_int(self.p, prec, rnd) def _mpmath_(self, prec, rnd): return mpmath.make_mpf(self._as_mpf_val(prec)) # TODO caching with decorator, but not to degrade performance @int_trace def __new__(cls, i): if isinstance(i, string_types): i = i.replace(' ', '') # whereas we cannot, in general, make a Rational from an # arbitrary expression, we can make an Integer unambiguously # (except when a non-integer expression happens to round to # an integer). So we proceed by taking int() of the input and # let the int routines determine whether the expression can # be made into an int or whether an error should be raised. try: ival = int(i) except TypeError: raise TypeError( "Argument of Integer should be of numeric type, got %s." % i) try: return _intcache[ival] except KeyError: # We only work with well-behaved integer types. This converts, for # example, numpy.int32 instances. obj = Expr.__new__(cls) obj.p = ival _intcache[ival] = obj return obj def __getnewargs__(self): return (self.p,) # Arithmetic operations are here for efficiency def __int__(self): return self.p __long__ = __int__ def floor(self): return Integer(self.p) def ceiling(self): return Integer(self.p) def __neg__(self): return Integer(-self.p) def __abs__(self): if self.p >= 0: return self else: return Integer(-self.p) def __divmod__(self, other): from .containers import Tuple if isinstance(other, Integer) and global_evaluate[0]: return Tuple(*(divmod(self.p, other.p))) else: return Number.__divmod__(self, other) def __rdivmod__(self, other): from .containers import Tuple if isinstance(other, integer_types) and global_evaluate[0]: return Tuple(*(divmod(other, self.p))) else: try: other = Number(other) except TypeError: msg = "unsupported operand type(s) for divmod(): '%s' and '%s'" oname = type(other).__name__ sname = type(self).__name__ raise TypeError(msg % (oname, sname)) return Number.__divmod__(other, self) # TODO make it decorator + bytecodehacks? def __add__(self, other): if global_evaluate[0]: if isinstance(other, integer_types): return Integer(self.p + other) elif isinstance(other, Integer): return Integer(self.p + other.p) elif isinstance(other, Rational): return Rational(self.p*other.q + other.p, other.q, 1) return Rational.__add__(self, other) else: return Add(self, other) def __radd__(self, other): if global_evaluate[0]: if isinstance(other, integer_types): return Integer(other + self.p) elif isinstance(other, Rational): return Rational(other.p + self.p*other.q, other.q, 1) return Rational.__radd__(self, other) return Rational.__radd__(self, other) def __sub__(self, other): if global_evaluate[0]: if isinstance(other, integer_types): return Integer(self.p - other) elif isinstance(other, Integer): return Integer(self.p - other.p) elif isinstance(other, Rational): return Rational(self.p*other.q - other.p, other.q, 1) return Rational.__sub__(self, other) return Rational.__sub__(self, other) def __rsub__(self, other): if global_evaluate[0]: if isinstance(other, integer_types): return Integer(other - self.p) elif isinstance(other, Rational): return Rational(other.p - self.p*other.q, other.q, 1) return Rational.__rsub__(self, other) return Rational.__rsub__(self, other) def __mul__(self, other): if global_evaluate[0]: if isinstance(other, integer_types): return Integer(self.p*other) elif isinstance(other, Integer): return Integer(self.p*other.p) elif isinstance(other, Rational): return Rational(self.p*other.p, other.q, igcd(self.p, other.q)) return Rational.__mul__(self, other) return Rational.__mul__(self, other) def __rmul__(self, other): if global_evaluate[0]: if isinstance(other, integer_types): return Integer(other*self.p) elif isinstance(other, Rational): return Rational(other.p*self.p, other.q, igcd(self.p, other.q)) return Rational.__rmul__(self, other) return Rational.__rmul__(self, other) def __mod__(self, other): if global_evaluate[0]: if isinstance(other, integer_types): return Integer(self.p % other) elif isinstance(other, Integer): return Integer(self.p % other.p) return Rational.__mod__(self, other) return Rational.__mod__(self, other) def __rmod__(self, other): if global_evaluate[0]: if isinstance(other, integer_types): return Integer(other % self.p) elif isinstance(other, Integer): return Integer(other.p % self.p) return Rational.__rmod__(self, other) return Rational.__rmod__(self, other) def __eq__(self, other): if isinstance(other, integer_types): return (self.p == other) elif isinstance(other, Integer): return (self.p == other.p) return Rational.__eq__(self, other) def __ne__(self, other): return not self == other def __gt__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s > %s" % (self, other)) if other.is_Integer: return _sympify(self.p > other.p) return Rational.__gt__(self, other) def __lt__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s < %s" % (self, other)) if other.is_Integer: return _sympify(self.p < other.p) return Rational.__lt__(self, other) def __ge__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s >= %s" % (self, other)) if other.is_Integer: return _sympify(self.p >= other.p) return Rational.__ge__(self, other) def __le__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s <= %s" % (self, other)) if other.is_Integer: return _sympify(self.p <= other.p) return Rational.__le__(self, other) def __hash__(self): return hash(self.p) def __index__(self): return self.p ######################################## def _eval_is_odd(self): return bool(self.p % 2) def _eval_power(self, expt): """ Tries to do some simplifications on self**expt Returns None if no further simplifications can be done When exponent is a fraction (so we have for example a square root), we try to find a simpler representation by factoring the argument up to factors of 2**15, e.g. - sqrt(4) becomes 2 - sqrt(-4) becomes 2*I - (2**(3+7)*3**(6+7))**Rational(1,7) becomes 6*18**(3/7) Further simplification would require a special call to factorint on the argument which is not done here for sake of speed. """ from sympy import perfect_power if expt is S.Infinity: if self.p > S.One: return S.Infinity # cases -1, 0, 1 are done in their respective classes return S.Infinity + S.ImaginaryUnit*S.Infinity if expt is S.NegativeInfinity: return Rational(1, self)**S.Infinity if not isinstance(expt, Number): # simplify when expt is even # (-2)**k --> 2**k if self.is_negative and expt.is_even: return (-self)**expt if isinstance(expt, Float): # Rational knows how to exponentiate by a Float return super(Integer, self)._eval_power(expt) if not isinstance(expt, Rational): return if expt is S.Half and self.is_negative: # we extract I for this special case since everyone is doing so return S.ImaginaryUnit*Pow(-self, expt) if expt.is_negative: # invert base and change sign on exponent ne = -expt if self.is_negative: return S.NegativeOne**expt*Rational(1, -self)**ne else: return Rational(1, self.p)**ne # see if base is a perfect root, sqrt(4) --> 2 x, xexact = integer_nthroot(abs(self.p), expt.q) if xexact: # if it's a perfect root we've finished result = Integer(x**abs(expt.p)) if self.is_negative: result *= S.NegativeOne**expt return result # The following is an algorithm where we collect perfect roots # from the factors of base. # if it's not an nth root, it still might be a perfect power b_pos = int(abs(self.p)) p = perfect_power(b_pos) if p is not False: dict = {p[0]: p[1]} else: dict = Integer(b_pos).factors(limit=2**15) # now process the dict of factors out_int = 1 # integer part out_rad = 1 # extracted radicals sqr_int = 1 sqr_gcd = 0 sqr_dict = {} for prime, exponent in dict.items(): exponent *= expt.p # remove multiples of expt.q: (2**12)**(1/10) -> 2*(2**2)**(1/10) div_e, div_m = divmod(exponent, expt.q) if div_e > 0: out_int *= prime**div_e if div_m > 0: # see if the reduced exponent shares a gcd with e.q # (2**2)**(1/10) -> 2**(1/5) g = igcd(div_m, expt.q) if g != 1: out_rad *= Pow(prime, Rational(div_m//g, expt.q//g)) else: sqr_dict[prime] = div_m # identify gcd of remaining powers for p, ex in sqr_dict.items(): if sqr_gcd == 0: sqr_gcd = ex else: sqr_gcd = igcd(sqr_gcd, ex) if sqr_gcd == 1: break for k, v in sqr_dict.items(): sqr_int *= k**(v//sqr_gcd) if sqr_int == b_pos and out_int == 1 and out_rad == 1: result = None else: result = out_int*out_rad*Pow(sqr_int, Rational(sqr_gcd, expt.q)) if self.is_negative: result *= Pow(S.NegativeOne, expt) return result def _eval_is_prime(self): from sympy.ntheory import isprime return isprime(self) def _eval_is_composite(self): if self > 1: return fuzzy_not(self.is_prime) else: return False def as_numer_denom(self): return self, S.One def __floordiv__(self, other): return Integer(self.p // Integer(other).p) def __rfloordiv__(self, other): return Integer(Integer(other).p // self.p) # Add sympify converters for i_type in integer_types: converter[i_type] = Integer class AlgebraicNumber(Expr): """Class for representing algebraic numbers in SymPy. """ __slots__ = ['rep', 'root', 'alias', 'minpoly'] is_AlgebraicNumber = True is_algebraic = True is_number = True def __new__(cls, expr, coeffs=None, alias=None, **args): """Construct a new algebraic number. """ from sympy import Poly from sympy.polys.polyclasses import ANP, DMP from sympy.polys.numberfields import minimal_polynomial from sympy.core.symbol import Symbol expr = sympify(expr) if isinstance(expr, (tuple, Tuple)): minpoly, root = expr if not minpoly.is_Poly: minpoly = Poly(minpoly) elif expr.is_AlgebraicNumber: minpoly, root = expr.minpoly, expr.root else: minpoly, root = minimal_polynomial( expr, args.get('gen'), polys=True), expr dom = minpoly.get_domain() if coeffs is not None: if not isinstance(coeffs, ANP): rep = DMP.from_sympy_list(sympify(coeffs), 0, dom) scoeffs = Tuple(*coeffs) else: rep = DMP.from_list(coeffs.to_list(), 0, dom) scoeffs = Tuple(*coeffs.to_list()) if rep.degree() >= minpoly.degree(): rep = rep.rem(minpoly.rep) else: rep = DMP.from_list([1, 0], 0, dom) scoeffs = Tuple(1, 0) sargs = (root, scoeffs) if alias is not None: if not isinstance(alias, Symbol): alias = Symbol(alias) sargs = sargs + (alias,) obj = Expr.__new__(cls, *sargs) obj.rep = rep obj.root = root obj.alias = alias obj.minpoly = minpoly return obj def __hash__(self): return super(AlgebraicNumber, self).__hash__() def _eval_evalf(self, prec): return self.as_expr()._evalf(prec) @property def is_aliased(self): """Returns ``True`` if ``alias`` was set. """ return self.alias is not None def as_poly(self, x=None): """Create a Poly instance from ``self``. """ from sympy import Dummy, Poly, PurePoly if x is not None: return Poly.new(self.rep, x) else: if self.alias is not None: return Poly.new(self.rep, self.alias) else: return PurePoly.new(self.rep, Dummy('x')) def as_expr(self, x=None): """Create a Basic expression from ``self``. """ return self.as_poly(x or self.root).as_expr().expand() def coeffs(self): """Returns all SymPy coefficients of an algebraic number. """ return [ self.rep.dom.to_sympy(c) for c in self.rep.all_coeffs() ] def native_coeffs(self): """Returns all native coefficients of an algebraic number. """ return self.rep.all_coeffs() def to_algebraic_integer(self): """Convert ``self`` to an algebraic integer. """ from sympy import Poly f = self.minpoly if f.LC() == 1: return self coeff = f.LC()**(f.degree() - 1) poly = f.compose(Poly(f.gen/f.LC())) minpoly = poly*coeff root = f.LC()*self.root return AlgebraicNumber((minpoly, root), self.coeffs()) def _eval_simplify(self, ratio, measure, rational, inverse): from sympy.polys import CRootOf, minpoly for r in [r for r in self.minpoly.all_roots() if r.func != CRootOf]: if minpoly(self.root - r).is_Symbol: # use the matching root if it's simpler if measure(r) < ratio*measure(self.root): return AlgebraicNumber(r) return self class RationalConstant(Rational): """ Abstract base class for rationals with specific behaviors Derived classes must define class attributes p and q and should probably all be singletons. """ __slots__ = [] def __new__(cls): return AtomicExpr.__new__(cls) class IntegerConstant(Integer): __slots__ = [] def __new__(cls): return AtomicExpr.__new__(cls) class Zero(with_metaclass(Singleton, IntegerConstant)): """The number zero. Zero is a singleton, and can be accessed by ``S.Zero`` Examples ======== >>> from sympy import S, Integer, zoo >>> Integer(0) is S.Zero True >>> 1/S.Zero zoo References ========== .. [1] https://en.wikipedia.org/wiki/Zero """ p = 0 q = 1 is_positive = False is_negative = False is_zero = True is_number = True __slots__ = [] @staticmethod def __abs__(): return S.Zero @staticmethod def __neg__(): return S.Zero def _eval_power(self, expt): if expt.is_positive: return self if expt.is_negative: return S.ComplexInfinity if expt.is_real is False: return S.NaN # infinities are already handled with pos and neg # tests above; now throw away leading numbers on Mul # exponent coeff, terms = expt.as_coeff_Mul() if coeff.is_negative: return S.ComplexInfinity**terms if coeff is not S.One: # there is a Number to discard return self**terms def _eval_order(self, *symbols): # Order(0,x) -> 0 return self def __nonzero__(self): return False __bool__ = __nonzero__ def as_coeff_Mul(self, rational=False): # XXX this routine should be deleted """Efficiently extract the coefficient of a summation. """ return S.One, self class One(with_metaclass(Singleton, IntegerConstant)): """The number one. One is a singleton, and can be accessed by ``S.One``. Examples ======== >>> from sympy import S, Integer >>> Integer(1) is S.One True References ========== .. [1] https://en.wikipedia.org/wiki/1_%28number%29 """ is_number = True p = 1 q = 1 __slots__ = [] @staticmethod def __abs__(): return S.One @staticmethod def __neg__(): return S.NegativeOne def _eval_power(self, expt): return self def _eval_order(self, *symbols): return @staticmethod def factors(limit=None, use_trial=True, use_rho=False, use_pm1=False, verbose=False, visual=False): if visual: return S.One else: return {} class NegativeOne(with_metaclass(Singleton, IntegerConstant)): """The number negative one. NegativeOne is a singleton, and can be accessed by ``S.NegativeOne``. Examples ======== >>> from sympy import S, Integer >>> Integer(-1) is S.NegativeOne True See Also ======== One References ========== .. [1] https://en.wikipedia.org/wiki/%E2%88%921_%28number%29 """ is_number = True p = -1 q = 1 __slots__ = [] @staticmethod def __abs__(): return S.One @staticmethod def __neg__(): return S.One def _eval_power(self, expt): if expt.is_odd: return S.NegativeOne if expt.is_even: return S.One if isinstance(expt, Number): if isinstance(expt, Float): return Float(-1.0)**expt if expt is S.NaN: return S.NaN if expt is S.Infinity or expt is S.NegativeInfinity: return S.NaN if expt is S.Half: return S.ImaginaryUnit if isinstance(expt, Rational): if expt.q == 2: return S.ImaginaryUnit**Integer(expt.p) i, r = divmod(expt.p, expt.q) if i: return self**i*self**Rational(r, expt.q) return class Half(with_metaclass(Singleton, RationalConstant)): """The rational number 1/2. Half is a singleton, and can be accessed by ``S.Half``. Examples ======== >>> from sympy import S, Rational >>> Rational(1, 2) is S.Half True References ========== .. [1] https://en.wikipedia.org/wiki/One_half """ is_number = True p = 1 q = 2 __slots__ = [] @staticmethod def __abs__(): return S.Half class Infinity(with_metaclass(Singleton, Number)): r"""Positive infinite quantity. In real analysis the symbol `\infty` denotes an unbounded limit: `x\to\infty` means that `x` grows without bound. Infinity is often used not only to define a limit but as a value in the affinely extended real number system. Points labeled `+\infty` and `-\infty` can be added to the topological space of the real numbers, producing the two-point compactification of the real numbers. Adding algebraic properties to this gives us the extended real numbers. Infinity is a singleton, and can be accessed by ``S.Infinity``, or can be imported as ``oo``. Examples ======== >>> from sympy import oo, exp, limit, Symbol >>> 1 + oo oo >>> 42/oo 0 >>> x = Symbol('x') >>> limit(exp(x), x, oo) oo See Also ======== NegativeInfinity, NaN References ========== .. [1] https://en.wikipedia.org/wiki/Infinity """ is_commutative = True is_positive = True is_infinite = True is_number = True is_prime = False __slots__ = [] def __new__(cls): return AtomicExpr.__new__(cls) def _latex(self, printer): return r"\infty" def _eval_subs(self, old, new): if self == old: return new @_sympifyit('other', NotImplemented) def __add__(self, other): if isinstance(other, Number): if other is S.NegativeInfinity or other is S.NaN: return S.NaN elif other.is_Float: if other == Float('-inf'): return S.NaN else: return Float('inf') else: return S.Infinity return NotImplemented __radd__ = __add__ @_sympifyit('other', NotImplemented) def __sub__(self, other): if isinstance(other, Number): if other is S.Infinity or other is S.NaN: return S.NaN elif other.is_Float: if other == Float('inf'): return S.NaN else: return Float('inf') else: return S.Infinity return NotImplemented @_sympifyit('other', NotImplemented) def __mul__(self, other): if isinstance(other, Number): if other is S.Zero or other is S.NaN: return S.NaN elif other.is_Float: if other == 0: return S.NaN if other > 0: return Float('inf') else: return Float('-inf') else: if other > 0: return S.Infinity else: return S.NegativeInfinity return NotImplemented __rmul__ = __mul__ @_sympifyit('other', NotImplemented) def __div__(self, other): if isinstance(other, Number): if other is S.Infinity or \ other is S.NegativeInfinity or \ other is S.NaN: return S.NaN elif other.is_Float: if other == Float('-inf') or \ other == Float('inf'): return S.NaN elif other.is_nonnegative: return Float('inf') else: return Float('-inf') else: if other >= 0: return S.Infinity else: return S.NegativeInfinity return NotImplemented __truediv__ = __div__ def __abs__(self): return S.Infinity def __neg__(self): return S.NegativeInfinity def _eval_power(self, expt): """ ``expt`` is symbolic object but not equal to 0 or 1. ================ ======= ============================== Expression Result Notes ================ ======= ============================== ``oo ** nan`` ``nan`` ``oo ** -p`` ``0`` ``p`` is number, ``oo`` ================ ======= ============================== See Also ======== Pow NaN NegativeInfinity """ from sympy.functions import re if expt.is_positive: return S.Infinity if expt.is_negative: return S.Zero if expt is S.NaN: return S.NaN if expt is S.ComplexInfinity: return S.NaN if expt.is_real is False and expt.is_number: expt_real = re(expt) if expt_real.is_positive: return S.ComplexInfinity if expt_real.is_negative: return S.Zero if expt_real.is_zero: return S.NaN return self**expt.evalf() def _as_mpf_val(self, prec): return mlib.finf def _sage_(self): import sage.all as sage return sage.oo def __hash__(self): return super(Infinity, self).__hash__() def __eq__(self, other): return other is S.Infinity def __ne__(self, other): return other is not S.Infinity def __lt__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s < %s" % (self, other)) if other.is_real: return S.false return Expr.__lt__(self, other) def __le__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s <= %s" % (self, other)) if other.is_real: if other.is_finite or other is S.NegativeInfinity: return S.false elif other.is_nonpositive: return S.false elif other.is_infinite and other.is_positive: return S.true return Expr.__le__(self, other) def __gt__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s > %s" % (self, other)) if other.is_real: if other.is_finite or other is S.NegativeInfinity: return S.true elif other.is_nonpositive: return S.true elif other.is_infinite and other.is_positive: return S.false return Expr.__gt__(self, other) def __ge__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s >= %s" % (self, other)) if other.is_real: return S.true return Expr.__ge__(self, other) def __mod__(self, other): return S.NaN __rmod__ = __mod__ def floor(self): return self def ceiling(self): return self oo = S.Infinity class NegativeInfinity(with_metaclass(Singleton, Number)): """Negative infinite quantity. NegativeInfinity is a singleton, and can be accessed by ``S.NegativeInfinity``. See Also ======== Infinity """ is_commutative = True is_negative = True is_infinite = True is_number = True __slots__ = [] def __new__(cls): return AtomicExpr.__new__(cls) def _latex(self, printer): return r"-\infty" def _eval_subs(self, old, new): if self == old: return new @_sympifyit('other', NotImplemented) def __add__(self, other): if isinstance(other, Number): if other is S.Infinity or other is S.NaN: return S.NaN elif other.is_Float: if other == Float('inf'): return Float('nan') else: return Float('-inf') else: return S.NegativeInfinity return NotImplemented __radd__ = __add__ @_sympifyit('other', NotImplemented) def __sub__(self, other): if isinstance(other, Number): if other is S.NegativeInfinity or other is S.NaN: return S.NaN elif other.is_Float: if other == Float('-inf'): return Float('nan') else: return Float('-inf') else: return S.NegativeInfinity return NotImplemented @_sympifyit('other', NotImplemented) def __mul__(self, other): if isinstance(other, Number): if other is S.Zero or other is S.NaN: return S.NaN elif other.is_Float: if other is S.NaN or other.is_zero: return S.NaN elif other.is_positive: return Float('-inf') else: return Float('inf') else: if other.is_positive: return S.NegativeInfinity else: return S.Infinity return NotImplemented __rmul__ = __mul__ @_sympifyit('other', NotImplemented) def __div__(self, other): if isinstance(other, Number): if other is S.Infinity or \ other is S.NegativeInfinity or \ other is S.NaN: return S.NaN elif other.is_Float: if other == Float('-inf') or \ other == Float('inf') or \ other is S.NaN: return S.NaN elif other.is_nonnegative: return Float('-inf') else: return Float('inf') else: if other >= 0: return S.NegativeInfinity else: return S.Infinity return NotImplemented __truediv__ = __div__ def __abs__(self): return S.Infinity def __neg__(self): return S.Infinity def _eval_power(self, expt): """ ``expt`` is symbolic object but not equal to 0 or 1. ================ ======= ============================== Expression Result Notes ================ ======= ============================== ``(-oo) ** nan`` ``nan`` ``(-oo) ** oo`` ``nan`` ``(-oo) ** -oo`` ``nan`` ``(-oo) ** e`` ``oo`` ``e`` is positive even integer ``(-oo) ** o`` ``-oo`` ``o`` is positive odd integer ================ ======= ============================== See Also ======== Infinity Pow NaN """ if expt.is_number: if expt is S.NaN or \ expt is S.Infinity or \ expt is S.NegativeInfinity: return S.NaN if isinstance(expt, Integer) and expt.is_positive: if expt.is_odd: return S.NegativeInfinity else: return S.Infinity return S.NegativeOne**expt*S.Infinity**expt def _as_mpf_val(self, prec): return mlib.fninf def _sage_(self): import sage.all as sage return -(sage.oo) def __hash__(self): return super(NegativeInfinity, self).__hash__() def __eq__(self, other): return other is S.NegativeInfinity def __ne__(self, other): return other is not S.NegativeInfinity def __lt__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s < %s" % (self, other)) if other.is_real: if other.is_finite or other is S.Infinity: return S.true elif other.is_nonnegative: return S.true elif other.is_infinite and other.is_negative: return S.false return Expr.__lt__(self, other) def __le__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s <= %s" % (self, other)) if other.is_real: return S.true return Expr.__le__(self, other) def __gt__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s > %s" % (self, other)) if other.is_real: return S.false return Expr.__gt__(self, other) def __ge__(self, other): try: other = _sympify(other) except SympifyError: raise TypeError("Invalid comparison %s >= %s" % (self, other)) if other.is_real: if other.is_finite or other is S.Infinity: return S.false elif other.is_nonnegative: return S.false elif other.is_infinite and other.is_negative: return S.true return Expr.__ge__(self, other) def __mod__(self, other): return S.NaN __rmod__ = __mod__ def floor(self): return self def ceiling(self): return self class NaN(with_metaclass(Singleton, Number)): """ Not a Number. This serves as a place holder for numeric values that are indeterminate. Most operations on NaN, produce another NaN. Most indeterminate forms, such as ``0/0`` or ``oo - oo` produce NaN. Two exceptions are ``0**0`` and ``oo**0``, which all produce ``1`` (this is consistent with Python's float). NaN is loosely related to floating point nan, which is defined in the IEEE 754 floating point standard, and corresponds to the Python ``float('nan')``. Differences are noted below. NaN is mathematically not equal to anything else, even NaN itself. This explains the initially counter-intuitive results with ``Eq`` and ``==`` in the examples below. NaN is not comparable so inequalities raise a TypeError. This is in constrast with floating point nan where all inequalities are false. NaN is a singleton, and can be accessed by ``S.NaN``, or can be imported as ``nan``. Examples ======== >>> from sympy import nan, S, oo, Eq >>> nan is S.NaN True >>> oo - oo nan >>> nan + 1 nan >>> Eq(nan, nan) # mathematical equality False >>> nan == nan # structural equality True References ========== .. [1] https://en.wikipedia.org/wiki/NaN """ is_commutative = True is_real = None is_rational = None is_algebraic = None is_transcendental = None is_integer = None is_comparable = False is_finite = None is_zero = None is_prime = None is_positive = None is_negative = None is_number = True __slots__ = [] def __new__(cls): return AtomicExpr.__new__(cls) def _latex(self, printer): return r"\mathrm{NaN}" @_sympifyit('other', NotImplemented) def __add__(self, other): return self @_sympifyit('other', NotImplemented) def __sub__(self, other): return self @_sympifyit('other', NotImplemented) def __mul__(self, other): return self @_sympifyit('other', NotImplemented) def __div__(self, other): return self __truediv__ = __div__ def floor(self): return self def ceiling(self): return self def _as_mpf_val(self, prec): return _mpf_nan def _sage_(self): import sage.all as sage return sage.NaN def __hash__(self): return super(NaN, self).__hash__() def __eq__(self, other): # NaN is structurally equal to another NaN return other is S.NaN def __ne__(self, other): return other is not S.NaN def _eval_Eq(self, other): # NaN is not mathematically equal to anything, even NaN return S.false # Expr will _sympify and raise TypeError __gt__ = Expr.__gt__ __ge__ = Expr.__ge__ __lt__ = Expr.__lt__ __le__ = Expr.__le__ nan = S.NaN class ComplexInfinity(with_metaclass(Singleton, AtomicExpr)): r"""Complex infinity. In complex analysis the symbol `\tilde\infty`, called "complex infinity", represents a quantity with infinite magnitude, but undetermined complex phase. ComplexInfinity is a singleton, and can be accessed by ``S.ComplexInfinity``, or can be imported as ``zoo``. Examples ======== >>> from sympy import zoo, oo >>> zoo + 42 zoo >>> 42/zoo 0 >>> zoo + zoo nan >>> zoo*zoo zoo See Also ======== Infinity """ is_commutative = True is_infinite = True is_number = True is_prime = False is_complex = True is_real = False __slots__ = [] def __new__(cls): return AtomicExpr.__new__(cls) def _latex(self, printer): return r"\tilde{\infty}" @staticmethod def __abs__(): return S.Infinity def floor(self): return self def ceiling(self): return self @staticmethod def __neg__(): return S.ComplexInfinity def _eval_power(self, expt): if expt is S.ComplexInfinity: return S.NaN if isinstance(expt, Number): if expt is S.Zero: return S.NaN else: if expt.is_positive: return S.ComplexInfinity else: return S.Zero def _sage_(self): import sage.all as sage return sage.UnsignedInfinityRing.gen() zoo = S.ComplexInfinity class NumberSymbol(AtomicExpr): is_commutative = True is_finite = True is_number = True __slots__ = [] is_NumberSymbol = True def __new__(cls): return AtomicExpr.__new__(cls) def approximation(self, number_cls): """ Return an interval with number_cls endpoints that contains the value of NumberSymbol. If not implemented, then return None. """ def _eval_evalf(self, prec): return Float._new(self._as_mpf_val(prec), prec) def __eq__(self, other): try: other = _sympify(other) except SympifyError: return NotImplemented if self is other: return True if other.is_Number and self.is_irrational: return False return False # NumberSymbol != non-(Number|self) def __ne__(self, other): return not self == other def __le__(self, other): if self is other: return S.true return Expr.__le__(self, other) def __ge__(self, other): if self is other: return S.true return Expr.__ge__(self, other) def __int__(self): # subclass with appropriate return value raise NotImplementedError def __long__(self): return self.__int__() def __hash__(self): return super(NumberSymbol, self).__hash__() class Exp1(with_metaclass(Singleton, NumberSymbol)): r"""The `e` constant. The transcendental number `e = 2.718281828\ldots` is the base of the natural logarithm and of the exponential function, `e = \exp(1)`. Sometimes called Euler's number or Napier's constant. Exp1 is a singleton, and can be accessed by ``S.Exp1``, or can be imported as ``E``. Examples ======== >>> from sympy import exp, log, E >>> E is exp(1) True >>> log(E) 1 References ========== .. [1] https://en.wikipedia.org/wiki/E_%28mathematical_constant%29 """ is_real = True is_positive = True is_negative = False # XXX Forces is_negative/is_nonnegative is_irrational = True is_number = True is_algebraic = False is_transcendental = True __slots__ = [] def _latex(self, printer): return r"e" @staticmethod def __abs__(): return S.Exp1 def __int__(self): return 2 def _as_mpf_val(self, prec): return mpf_e(prec) def approximation_interval(self, number_cls): if issubclass(number_cls, Integer): return (Integer(2), Integer(3)) elif issubclass(number_cls, Rational): pass def _eval_power(self, expt): from sympy import exp return exp(expt) def _eval_rewrite_as_sin(self, **kwargs): from sympy import sin I = S.ImaginaryUnit return sin(I + S.Pi/2) - I*sin(I) def _eval_rewrite_as_cos(self, **kwargs): from sympy import cos I = S.ImaginaryUnit return cos(I) + I*cos(I + S.Pi/2) def _sage_(self): import sage.all as sage return sage.e E = S.Exp1 class Pi(with_metaclass(Singleton, NumberSymbol)): r"""The `\pi` constant. The transcendental number `\pi = 3.141592654\ldots` represents the ratio of a circle's circumference to its diameter, the area of the unit circle, the half-period of trigonometric functions, and many other things in mathematics. Pi is a singleton, and can be accessed by ``S.Pi``, or can be imported as ``pi``. Examples ======== >>> from sympy import S, pi, oo, sin, exp, integrate, Symbol >>> S.Pi pi >>> pi > 3 True >>> pi.is_irrational True >>> x = Symbol('x') >>> sin(x + 2*pi) sin(x) >>> integrate(exp(-x**2), (x, -oo, oo)) sqrt(pi) References ========== .. [1] https://en.wikipedia.org/wiki/Pi """ is_real = True is_positive = True is_negative = False is_irrational = True is_number = True is_algebraic = False is_transcendental = True __slots__ = [] def _latex(self, printer): return r"\pi" @staticmethod def __abs__(): return S.Pi def __int__(self): return 3 def _as_mpf_val(self, prec): return mpf_pi(prec) def approximation_interval(self, number_cls): if issubclass(number_cls, Integer): return (Integer(3), Integer(4)) elif issubclass(number_cls, Rational): return (Rational(223, 71), Rational(22, 7)) def _sage_(self): import sage.all as sage return sage.pi pi = S.Pi class GoldenRatio(with_metaclass(Singleton, NumberSymbol)): r"""The golden ratio, `\phi`. `\phi = \frac{1 + \sqrt{5}}{2}` is algebraic number. Two quantities are in the golden ratio if their ratio is the same as the ratio of their sum to the larger of the two quantities, i.e. their maximum. GoldenRatio is a singleton, and can be accessed by ``S.GoldenRatio``. Examples ======== >>> from sympy import S >>> S.GoldenRatio > 1 True >>> S.GoldenRatio.expand(func=True) 1/2 + sqrt(5)/2 >>> S.GoldenRatio.is_irrational True References ========== .. [1] https://en.wikipedia.org/wiki/Golden_ratio """ is_real = True is_positive = True is_negative = False is_irrational = True is_number = True is_algebraic = True is_transcendental = False __slots__ = [] def _latex(self, printer): return r"\phi" def __int__(self): return 1 def _as_mpf_val(self, prec): # XXX track down why this has to be increased rv = mlib.from_man_exp(phi_fixed(prec + 10), -prec - 10) return mpf_norm(rv, prec) def _eval_expand_func(self, **hints): from sympy import sqrt return S.Half + S.Half*sqrt(5) def approximation_interval(self, number_cls): if issubclass(number_cls, Integer): return (S.One, Rational(2)) elif issubclass(number_cls, Rational): pass def _sage_(self): import sage.all as sage return sage.golden_ratio _eval_rewrite_as_sqrt = _eval_expand_func class TribonacciConstant(with_metaclass(Singleton, NumberSymbol)): r"""The tribonacci constant. The tribonacci numbers are like the Fibonacci numbers, but instead of starting with two predetermined terms, the sequence starts with three predetermined terms and each term afterwards is the sum of the preceding three terms. The tribonacci constant is the ratio toward which adjacent tribonacci numbers tend. It is a root of the polynomial `x^3 - x^2 - x - 1 = 0`, and also satisfies the equation `x + x^{-3} = 2`. TribonacciConstant is a singleton, and can be accessed by ``S.TribonacciConstant``. Examples ======== >>> from sympy import S >>> S.TribonacciConstant > 1 True >>> S.TribonacciConstant.expand(func=True) 1/3 + (-3*sqrt(33) + 19)**(1/3)/3 + (3*sqrt(33) + 19)**(1/3)/3 >>> S.TribonacciConstant.is_irrational True >>> S.TribonacciConstant.n(20) 1.8392867552141611326 References ========== .. [1] https://en.wikipedia.org/wiki/Generalizations_of_Fibonacci_numbers#Tribonacci_numbers """ is_real = True is_positive = True is_negative = False is_irrational = True is_number = True is_algebraic = True is_transcendental = False __slots__ = [] def _latex(self, printer): return r"\mathrm{TribonacciConstant}" def __int__(self): return 2 def _eval_evalf(self, prec): rv = self._eval_expand_func(function=True)._eval_evalf(prec + 4) return Float(rv, precision=prec) def _eval_expand_func(self, **hints): from sympy import sqrt, cbrt return (1 + cbrt(19 - 3*sqrt(33)) + cbrt(19 + 3*sqrt(33))) / 3 def approximation_interval(self, number_cls): if issubclass(number_cls, Integer): return (S.One, Rational(2)) elif issubclass(number_cls, Rational): pass _eval_rewrite_as_sqrt = _eval_expand_func class EulerGamma(with_metaclass(Singleton, NumberSymbol)): r"""The Euler-Mascheroni constant. `\gamma = 0.5772157\ldots` (also called Euler's constant) is a mathematical constant recurring in analysis and number theory. It is defined as the limiting difference between the harmonic series and the natural logarithm: .. math:: \gamma = \lim\limits_{n\to\infty} \left(\sum\limits_{k=1}^n\frac{1}{k} - \ln n\right) EulerGamma is a singleton, and can be accessed by ``S.EulerGamma``. Examples ======== >>> from sympy import S >>> S.EulerGamma.is_irrational >>> S.EulerGamma > 0 True >>> S.EulerGamma > 1 False References ========== .. [1] https://en.wikipedia.org/wiki/Euler%E2%80%93Mascheroni_constant """ is_real = True is_positive = True is_negative = False is_irrational = None is_number = True __slots__ = [] def _latex(self, printer): return r"\gamma" def __int__(self): return 0 def _as_mpf_val(self, prec): # XXX track down why this has to be increased v = mlib.libhyper.euler_fixed(prec + 10) rv = mlib.from_man_exp(v, -prec - 10) return mpf_norm(rv, prec) def approximation_interval(self, number_cls): if issubclass(number_cls, Integer): return (S.Zero, S.One) elif issubclass(number_cls, Rational): return (S.Half, Rational(3, 5)) def _sage_(self): import sage.all as sage return sage.euler_gamma class Catalan(with_metaclass(Singleton, NumberSymbol)): r"""Catalan's constant. `K = 0.91596559\ldots` is given by the infinite series .. math:: K = \sum_{k=0}^{\infty} \frac{(-1)^k}{(2k+1)^2} Catalan is a singleton, and can be accessed by ``S.Catalan``. Examples ======== >>> from sympy import S >>> S.Catalan.is_irrational >>> S.Catalan > 0 True >>> S.Catalan > 1 False References ========== .. [1] https://en.wikipedia.org/wiki/Catalan%27s_constant """ is_real = True is_positive = True is_negative = False is_irrational = None is_number = True __slots__ = [] def __int__(self): return 0 def _as_mpf_val(self, prec): # XXX track down why this has to be increased v = mlib.catalan_fixed(prec + 10) rv = mlib.from_man_exp(v, -prec - 10) return mpf_norm(rv, prec) def approximation_interval(self, number_cls): if issubclass(number_cls, Integer): return (S.Zero, S.One) elif issubclass(number_cls, Rational): return (Rational(9, 10), S.One) def _sage_(self): import sage.all as sage return sage.catalan class ImaginaryUnit(with_metaclass(Singleton, AtomicExpr)): r"""The imaginary unit, `i = \sqrt{-1}`. I is a singleton, and can be accessed by ``S.I``, or can be imported as ``I``. Examples ======== >>> from sympy import I, sqrt >>> sqrt(-1) I >>> I*I -1 >>> 1/I -I References ========== .. [1] https://en.wikipedia.org/wiki/Imaginary_unit """ is_commutative = True is_imaginary = True is_finite = True is_number = True is_algebraic = True is_transcendental = False __slots__ = [] def _latex(self, printer): return r"i" @staticmethod def __abs__(): return S.One def _eval_evalf(self, prec): return self def _eval_conjugate(self): return -S.ImaginaryUnit def _eval_power(self, expt): """ b is I = sqrt(-1) e is symbolic object but not equal to 0, 1 I**r -> (-1)**(r/2) -> exp(r/2*Pi*I) -> sin(Pi*r/2) + cos(Pi*r/2)*I, r is decimal I**0 mod 4 -> 1 I**1 mod 4 -> I I**2 mod 4 -> -1 I**3 mod 4 -> -I """ if isinstance(expt, Number): if isinstance(expt, Integer): expt = expt.p % 4 if expt == 0: return S.One if expt == 1: return S.ImaginaryUnit if expt == 2: return -S.One return -S.ImaginaryUnit return def as_base_exp(self): return S.NegativeOne, S.Half def _sage_(self): import sage.all as sage return sage.I @property def _mpc_(self): return (Float(0)._mpf_, Float(1)._mpf_) I = S.ImaginaryUnit def sympify_fractions(f): return Rational(f.numerator, f.denominator, 1) converter[fractions.Fraction] = sympify_fractions try: if HAS_GMPY == 2: import gmpy2 as gmpy elif HAS_GMPY == 1: import gmpy else: raise ImportError def sympify_mpz(x): return Integer(long(x)) def sympify_mpq(x): return Rational(long(x.numerator), long(x.denominator)) converter[type(gmpy.mpz(1))] = sympify_mpz converter[type(gmpy.mpq(1, 2))] = sympify_mpq except ImportError: pass def sympify_mpmath(x): return Expr._from_mpmath(x, x.context.prec) converter[mpnumeric] = sympify_mpmath def sympify_mpq(x): p, q = x._mpq_ return Rational(p, q, 1) converter[type(mpmath.rational.mpq(1, 2))] = sympify_mpq def sympify_complex(a): real, imag = list(map(sympify, (a.real, a.imag))) return real + S.ImaginaryUnit*imag converter[complex] = sympify_complex _intcache[0] = S.Zero _intcache[1] = S.One _intcache[-1] = S.NegativeOne from .power import Pow, integer_nthroot from .mul import Mul Mul.identity = One() from .add import Add Add.identity = Zero()

894eb3f15c93b0778af6259ba6b3a825257c6f502bf6483939e5cfb99f7e6342

from __future__ import print_function, division from sympy.core.sympify import _sympify, sympify from sympy.core.basic import Basic from sympy.core.cache import cacheit from sympy.core.compatibility import ordered, range from sympy.core.logic import fuzzy_and from sympy.core.evaluate import global_evaluate from sympy.utilities.iterables import sift class AssocOp(Basic): """ Associative operations, can separate noncommutative and commutative parts. (a op b) op c == a op (b op c) == a op b op c. Base class for Add and Mul. This is an abstract base class, concrete derived classes must define the attribute `identity`. """ # for performance reason, we don't let is_commutative go to assumptions, # and keep it right here __slots__ = ['is_commutative'] @cacheit def __new__(cls, *args, **options): from sympy import Order args = list(map(_sympify, args)) args = [a for a in args if a is not cls.identity] evaluate = options.get('evaluate') if evaluate is None: evaluate = global_evaluate[0] if not evaluate: return cls._from_args(args) if len(args) == 0: return cls.identity if len(args) == 1: return args[0] c_part, nc_part, order_symbols = cls.flatten(args) is_commutative = not nc_part obj = cls._from_args(c_part + nc_part, is_commutative) obj = cls._exec_constructor_postprocessors(obj) if order_symbols is not None: return Order(obj, *order_symbols) return obj @classmethod def _from_args(cls, args, is_commutative=None): """Create new instance with already-processed args""" if len(args) == 0: return cls.identity elif len(args) == 1: return args[0] obj = super(AssocOp, cls).__new__(cls, *args) if is_commutative is None: is_commutative = fuzzy_and(a.is_commutative for a in args) obj.is_commutative = is_commutative return obj def _new_rawargs(self, *args, **kwargs): """Create new instance of own class with args exactly as provided by caller but returning the self class identity if args is empty. This is handy when we want to optimize things, e.g. >>> from sympy import Mul, S >>> from sympy.abc import x, y >>> e = Mul(3, x, y) >>> e.args (3, x, y) >>> Mul(*e.args[1:]) x*y >>> e._new_rawargs(*e.args[1:]) # the same as above, but faster x*y Note: use this with caution. There is no checking of arguments at all. This is best used when you are rebuilding an Add or Mul after simply removing one or more args. If, for example, modifications, result in extra 1s being inserted (as when collecting an expression's numerators and denominators) they will not show up in the result but a Mul will be returned nonetheless: >>> m = (x*y)._new_rawargs(S.One, x); m x >>> m == x False >>> m.is_Mul True Another issue to be aware of is that the commutativity of the result is based on the commutativity of self. If you are rebuilding the terms that came from a commutative object then there will be no problem, but if self was non-commutative then what you are rebuilding may now be commutative. Although this routine tries to do as little as possible with the input, getting the commutativity right is important, so this level of safety is enforced: commutativity will always be recomputed if self is non-commutative and kwarg `reeval=False` has not been passed. """ if kwargs.pop('reeval', True) and self.is_commutative is False: is_commutative = None else: is_commutative = self.is_commutative return self._from_args(args, is_commutative) @classmethod def flatten(cls, seq): """Return seq so that none of the elements are of type `cls`. This is the vanilla routine that will be used if a class derived from AssocOp does not define its own flatten routine.""" # apply associativity, no commutativity property is used new_seq = [] while seq: o = seq.pop() if o.__class__ is cls: # classes must match exactly seq.extend(o.args) else: new_seq.append(o) # c_part, nc_part, order_symbols return [], new_seq, None def _matches_commutative(self, expr, repl_dict={}, old=False): """ Matches Add/Mul "pattern" to an expression "expr". repl_dict ... a dictionary of (wild: expression) pairs, that get returned with the results This function is the main workhorse for Add/Mul. For instance: >>> from sympy import symbols, Wild, sin >>> a = Wild("a") >>> b = Wild("b") >>> c = Wild("c") >>> x, y, z = symbols("x y z") >>> (a+sin(b)*c)._matches_commutative(x+sin(y)*z) {a_: x, b_: y, c_: z} In the example above, "a+sin(b)*c" is the pattern, and "x+sin(y)*z" is the expression. The repl_dict contains parts that were already matched. For example here: >>> (x+sin(b)*c)._matches_commutative(x+sin(y)*z, repl_dict={a: x}) {a_: x, b_: y, c_: z} the only function of the repl_dict is to return it in the result, e.g. if you omit it: >>> (x+sin(b)*c)._matches_commutative(x+sin(y)*z) {b_: y, c_: z} the "a: x" is not returned in the result, but otherwise it is equivalent. """ # make sure expr is Expr if pattern is Expr from .expr import Add, Expr from sympy import Mul if isinstance(self, Expr) and not isinstance(expr, Expr): return None # handle simple patterns if self == expr: return repl_dict d = self._matches_simple(expr, repl_dict) if d is not None: return d # eliminate exact part from pattern: (2+a+w1+w2).matches(expr) -> (w1+w2).matches(expr-a-2) from .function import WildFunction from .symbol import Wild wild_part, exact_part = sift(self.args, lambda p: p.has(Wild, WildFunction) and not expr.has(p), binary=True) if not exact_part: wild_part = list(ordered(wild_part)) else: exact = self._new_rawargs(*exact_part) free = expr.free_symbols if free and (exact.free_symbols - free): # there are symbols in the exact part that are not # in the expr; but if there are no free symbols, let # the matching continue return None newexpr = self._combine_inverse(expr, exact) if not old and (expr.is_Add or expr.is_Mul): if newexpr.count_ops() > expr.count_ops(): return None newpattern = self._new_rawargs(*wild_part) return newpattern.matches(newexpr, repl_dict) # now to real work ;) i = 0 saw = set() while expr not in saw: saw.add(expr) expr_list = (self.identity,) + tuple(ordered(self.make_args(expr))) for last_op in reversed(expr_list): for w in reversed(wild_part): d1 = w.matches(last_op, repl_dict) if d1 is not None: d2 = self.xreplace(d1).matches(expr, d1) if d2 is not None: return d2 if i == 0: if self.is_Mul: # make e**i look like Mul if expr.is_Pow and expr.exp.is_Integer: if expr.exp > 0: expr = Mul(*[expr.base, expr.base**(expr.exp - 1)], evaluate=False) else: expr = Mul(*[1/expr.base, expr.base**(expr.exp + 1)], evaluate=False) i += 1 continue elif self.is_Add: # make i*e look like Add c, e = expr.as_coeff_Mul() if abs(c) > 1: if c > 0: expr = Add(*[e, (c - 1)*e], evaluate=False) else: expr = Add(*[-e, (c + 1)*e], evaluate=False) i += 1 continue # try collection on non-Wild symbols from sympy.simplify.radsimp import collect was = expr did = set() for w in reversed(wild_part): c, w = w.as_coeff_mul(Wild) free = c.free_symbols - did if free: did.update(free) expr = collect(expr, free) if expr != was: i += 0 continue break # if we didn't continue, there is nothing more to do return def _has_matcher(self): """Helper for .has()""" def _ncsplit(expr): # this is not the same as args_cnc because here # we don't assume expr is a Mul -- hence deal with args -- # and always return a set. cpart, ncpart = sift(expr.args, lambda arg: arg.is_commutative is True, binary=True) return set(cpart), ncpart c, nc = _ncsplit(self) cls = self.__class__ def is_in(expr): if expr == self: return True elif not isinstance(expr, Basic): return False elif isinstance(expr, cls): _c, _nc = _ncsplit(expr) if (c & _c) == c: if not nc: return True elif len(nc) <= len(_nc): for i in range(len(_nc) - len(nc) + 1): if _nc[i:i + len(nc)] == nc: return True return False return is_in def _eval_evalf(self, prec): """ Evaluate the parts of self that are numbers; if the whole thing was a number with no functions it would have been evaluated, but it wasn't so we must judiciously extract the numbers and reconstruct the object. This is *not* simply replacing numbers with evaluated numbers. Nunmbers should be handled in the largest pure-number expression as possible. So the code below separates ``self`` into number and non-number parts and evaluates the number parts and walks the args of the non-number part recursively (doing the same thing). """ from .add import Add from .mul import Mul from .symbol import Symbol from .function import AppliedUndef if isinstance(self, (Mul, Add)): x, tail = self.as_independent(Symbol, AppliedUndef) # if x is an AssocOp Function then the _evalf below will # call _eval_evalf (here) so we must break the recursion if not (tail is self.identity or isinstance(x, AssocOp) and x.is_Function or x is self.identity and isinstance(tail, AssocOp)): # here, we have a number so we just call to _evalf with prec; # prec is not the same as n, it is the binary precision so # that's why we don't call to evalf. x = x._evalf(prec) if x is not self.identity else self.identity args = [] tail_args = tuple(self.func.make_args(tail)) for a in tail_args: # here we call to _eval_evalf since we don't know what we # are dealing with and all other _eval_evalf routines should # be doing the same thing (i.e. taking binary prec and # finding the evalf-able args) newa = a._eval_evalf(prec) if newa is None: args.append(a) else: args.append(newa) return self.func(x, *args) # this is the same as above, but there were no pure-number args to # deal with args = [] for a in self.args: newa = a._eval_evalf(prec) if newa is None: args.append(a) else: args.append(newa) return self.func(*args) @classmethod def make_args(cls, expr): """ Return a sequence of elements `args` such that cls(*args) == expr >>> from sympy import Symbol, Mul, Add >>> x, y = map(Symbol, 'xy') >>> Mul.make_args(x*y) (x, y) >>> Add.make_args(x*y) (x*y,) >>> set(Add.make_args(x*y + y)) == set([y, x*y]) True """ if isinstance(expr, cls): return expr.args else: return (sympify(expr),) class ShortCircuit(Exception): pass class LatticeOp(AssocOp): """ Join/meet operations of an algebraic lattice[1]. These binary operations are associative (op(op(a, b), c) = op(a, op(b, c))), commutative (op(a, b) = op(b, a)) and idempotent (op(a, a) = op(a) = a). Common examples are AND, OR, Union, Intersection, max or min. They have an identity element (op(identity, a) = a) and an absorbing element conventionally called zero (op(zero, a) = zero). This is an abstract base class, concrete derived classes must declare attributes zero and identity. All defining properties are then respected. >>> from sympy import Integer >>> from sympy.core.operations import LatticeOp >>> class my_join(LatticeOp): ... zero = Integer(0) ... identity = Integer(1) >>> my_join(2, 3) == my_join(3, 2) True >>> my_join(2, my_join(3, 4)) == my_join(2, 3, 4) True >>> my_join(0, 1, 4, 2, 3, 4) 0 >>> my_join(1, 2) 2 References: [1] - https://en.wikipedia.org/wiki/Lattice_%28order%29 """ is_commutative = True def __new__(cls, *args, **options): args = (_sympify(arg) for arg in args) try: # /!\ args is a generator and _new_args_filter # must be careful to handle as such; this # is done so short-circuiting can be done # without having to sympify all values _args = frozenset(cls._new_args_filter(args)) except ShortCircuit: return sympify(cls.zero) if not _args: return sympify(cls.identity) elif len(_args) == 1: return set(_args).pop() else: # XXX in almost every other case for __new__, *_args is # passed along, but the expectation here is for _args obj = super(AssocOp, cls).__new__(cls, _args) obj._argset = _args return obj @classmethod def _new_args_filter(cls, arg_sequence, call_cls=None): """Generator filtering args""" ncls = call_cls or cls for arg in arg_sequence: if arg == ncls.zero: raise ShortCircuit(arg) elif arg == ncls.identity: continue elif arg.func == ncls: for x in arg.args: yield x else: yield arg @classmethod def make_args(cls, expr): """ Return a set of args such that cls(*arg_set) == expr. """ if isinstance(expr, cls): return expr._argset else: return frozenset([sympify(expr)]) @property @cacheit def args(self): return tuple(ordered(self._argset)) @staticmethod def _compare_pretty(a, b): return (str(a) > str(b)) - (str(a) < str(b))

9506768d5435866ed41339a1c9fa63d259b6d06fb59b64b269678da529df165d

from __future__ import print_function from sympy.matrices.dense import MutableDenseMatrix from sympy.polys.polytools import Poly from sympy.polys.domains import EX class MutablePolyDenseMatrix(MutableDenseMatrix): """ A mutable matrix of objects from poly module or to operate with them. Examples ======== >>> from sympy.polys.polymatrix import PolyMatrix >>> from sympy import Symbol, Poly, ZZ >>> x = Symbol('x') >>> pm1 = PolyMatrix([[Poly(x**2, x), Poly(-x, x)], [Poly(x**3, x), Poly(-1 + x, x)]]) >>> v1 = PolyMatrix([[1, 0], [-1, 0]]) >>> pm1*v1 Matrix([ [ Poly(x**2 + x, x, domain='ZZ'), Poly(0, x, domain='ZZ')], [Poly(x**3 - x + 1, x, domain='ZZ'), Poly(0, x, domain='ZZ')]]) >>> pm1.ring ZZ[x] >>> v1*pm1 Matrix([ [ Poly(x**2, x, domain='ZZ'), Poly(-x, x, domain='ZZ')], [Poly(-x**2, x, domain='ZZ'), Poly(x, x, domain='ZZ')]]) >>> pm2 = PolyMatrix([[Poly(x**2, x, domain='QQ'), Poly(0, x, domain='QQ'), Poly(1, x, domain='QQ'), \ Poly(x**3, x, domain='QQ'), Poly(0, x, domain='QQ'), Poly(-x**3, x, domain='QQ')]]) >>> v2 = PolyMatrix([1, 0, 0, 0, 0, 0], ring=ZZ) >>> v2.ring ZZ >>> pm2*v2 Matrix([[Poly(x**2, x, domain='QQ')]]) """ _class_priority = 10 # we don't want to sympify the elements of PolyMatrix _sympify = staticmethod(lambda x: x) def __init__(self, *args, **kwargs): # if any non-Poly element is given as input then # 'ring' defaults 'EX' ring = kwargs.get('ring', EX) if all(isinstance(p, Poly) for p in self._mat) and self._mat: domain = tuple([p.domain[p.gens] for p in self._mat]) ring = domain[0] for i in range(1, len(domain)): ring = ring.unify(domain[i]) self.ring = ring def _eval_matrix_mul(self, other): self_rows, self_cols = self.rows, self.cols other_rows, other_cols = other.rows, other.cols other_len = other_rows * other_cols new_mat_rows = self.rows new_mat_cols = other.cols new_mat = [0]*new_mat_rows*new_mat_cols if self.cols != 0 and other.rows != 0: mat = self._mat other_mat = other._mat for i in range(len(new_mat)): row, col = i // new_mat_cols, i % new_mat_cols row_indices = range(self_cols*row, self_cols*(row+1)) col_indices = range(col, other_len, other_cols) vec = (mat[a]*other_mat[b] for a,b in zip(row_indices, col_indices)) # 'Add' shouldn't be used here new_mat[i] = sum(vec) return self.__class__(new_mat_rows, new_mat_cols, new_mat, copy=False) def _eval_scalar_mul(self, other): mat = [Poly(a.as_expr()*other, *a.gens) if isinstance(a, Poly) else a*other for a in self._mat] return self.__class__(self.rows, self.cols, mat, copy=False) def _eval_scalar_rmul(self, other): mat = [Poly(other*a.as_expr(), *a.gens) if isinstance(a, Poly) else other*a for a in self._mat] return self.__class__(self.rows, self.cols, mat, copy=False) MutablePolyMatrix = PolyMatrix = MutablePolyDenseMatrix

284208f19a492e41025933e38a7026df9291efc6edca22ac0659892b5f4ab8b2

"""Power series evaluation and manipulation using sparse Polynomials Implementing a new function --------------------------- There are a few things to be kept in mind when adding a new function here:: - The implementation should work on all possible input domains/rings. Special cases include the ``EX`` ring and a constant term in the series to be expanded. There can be two types of constant terms in the series: + A constant value or symbol. + A term of a multivariate series not involving the generator, with respect to which the series is to expanded. Strictly speaking, a generator of a ring should not be considered a constant. However, for series expansion both the cases need similar treatment (as the user doesn't care about inner details), i.e, use an addition formula to separate the constant part and the variable part (see rs_sin for reference). - All the algorithms used here are primarily designed to work for Taylor series (number of iterations in the algo equals the required order). Hence, it becomes tricky to get the series of the right order if a Puiseux series is input. Use rs_puiseux? in your function if your algorithm is not designed to handle fractional powers. Extending rs_series ------------------- To make a function work with rs_series you need to do two things:: - Many sure it works with a constant term (as explained above). - If the series contains constant terms, you might need to extend its ring. You do so by adding the new terms to the rings as generators. ``PolyRing.compose`` and ``PolyRing.add_gens`` are two functions that do so and need to be called every time you expand a series containing a constant term. Look at rs_sin and rs_series for further reference. """ from sympy.polys.domains import QQ, EX from sympy.polys.rings import PolyElement, ring, sring from sympy.polys.polyerrors import DomainError from sympy.polys.monomials import (monomial_min, monomial_mul, monomial_div, monomial_ldiv) from mpmath.libmp.libintmath import ifac from sympy.core import PoleError, Function, Expr from sympy.core.numbers import Rational, igcd from sympy.core.compatibility import as_int, range from sympy.functions import sin, cos, tan, atan, exp, atanh, tanh, log, ceiling from mpmath.libmp.libintmath import giant_steps import math def _invert_monoms(p1): """ Compute ``x**n * p1(1/x)`` for a univariate polynomial ``p1`` in ``x``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import _invert_monoms >>> R, x = ring('x', ZZ) >>> p = x**2 + 2*x + 3 >>> _invert_monoms(p) 3*x**2 + 2*x + 1 See Also ======== sympy.polys.densebasic.dup_reverse """ terms = list(p1.items()) terms.sort() deg = p1.degree() R = p1.ring p = R.zero cv = p1.listcoeffs() mv = p1.listmonoms() for i in range(len(mv)): p[(deg - mv[i][0],)] = cv[i] return p def _giant_steps(target): """Return a list of precision steps for the Newton's method""" res = giant_steps(2, target) if res[0] != 2: res = [2] + res return res def rs_trunc(p1, x, prec): """ Truncate the series in the ``x`` variable with precision ``prec``, that is, modulo ``O(x**prec)`` Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_trunc >>> R, x = ring('x', QQ) >>> p = x**10 + x**5 + x + 1 >>> rs_trunc(p, x, 12) x**10 + x**5 + x + 1 >>> rs_trunc(p, x, 10) x**5 + x + 1 """ R = p1.ring p = R.zero i = R.gens.index(x) for exp1 in p1: if exp1[i] >= prec: continue p[exp1] = p1[exp1] return p def rs_is_puiseux(p, x): """ Test if ``p`` is Puiseux series in ``x``. Raise an exception if it has a negative power in ``x``. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_is_puiseux >>> R, x = ring('x', QQ) >>> p = x**QQ(2,5) + x**QQ(2,3) + x >>> rs_is_puiseux(p, x) True """ index = p.ring.gens.index(x) for k in p: if k[index] != int(k[index]): return True if k[index] < 0: raise ValueError('The series is not regular in %s' % x) return False def rs_puiseux(f, p, x, prec): """ Return the puiseux series for `f(p, x, prec)`. To be used when function ``f`` is implemented only for regular series. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_puiseux, rs_exp >>> R, x = ring('x', QQ) >>> p = x**QQ(2,5) + x**QQ(2,3) + x >>> rs_puiseux(rs_exp,p, x, 1) 1/2*x**(4/5) + x**(2/3) + x**(2/5) + 1 """ index = p.ring.gens.index(x) n = 1 for k in p: power = k[index] if isinstance(power, Rational): num, den = power.as_numer_denom() n = int(n*den // igcd(n, den)) elif power != int(power): den = power.denominator n = int(n*den // igcd(n, den)) if n != 1: p1 = pow_xin(p, index, n) r = f(p1, x, prec*n) n1 = QQ(1, n) if isinstance(r, tuple): r = tuple([pow_xin(rx, index, n1) for rx in r]) else: r = pow_xin(r, index, n1) else: r = f(p, x, prec) return r def rs_puiseux2(f, p, q, x, prec): """ Return the puiseux series for `f(p, q, x, prec)`. To be used when function ``f`` is implemented only for regular series. """ index = p.ring.gens.index(x) n = 1 for k in p: power = k[index] if isinstance(power, Rational): num, den = power.as_numer_denom() n = n*den // igcd(n, den) elif power != int(power): den = power.denominator n = n*den // igcd(n, den) if n != 1: p1 = pow_xin(p, index, n) r = f(p1, q, x, prec*n) n1 = QQ(1, n) r = pow_xin(r, index, n1) else: r = f(p, q, x, prec) return r def rs_mul(p1, p2, x, prec): """ Return the product of the given two series, modulo ``O(x**prec)``. ``x`` is the series variable or its position in the generators. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_mul >>> R, x = ring('x', QQ) >>> p1 = x**2 + 2*x + 1 >>> p2 = x + 1 >>> rs_mul(p1, p2, x, 3) 3*x**2 + 3*x + 1 """ R = p1.ring p = R.zero if R.__class__ != p2.ring.__class__ or R != p2.ring: raise ValueError('p1 and p2 must have the same ring') iv = R.gens.index(x) if not isinstance(p2, PolyElement): raise ValueError('p1 and p2 must have the same ring') if R == p2.ring: get = p.get items2 = list(p2.items()) items2.sort(key=lambda e: e[0][iv]) if R.ngens == 1: for exp1, v1 in p1.items(): for exp2, v2 in items2: exp = exp1[0] + exp2[0] if exp < prec: exp = (exp, ) p[exp] = get(exp, 0) + v1*v2 else: break else: monomial_mul = R.monomial_mul for exp1, v1 in p1.items(): for exp2, v2 in items2: if exp1[iv] + exp2[iv] < prec: exp = monomial_mul(exp1, exp2) p[exp] = get(exp, 0) + v1*v2 else: break p.strip_zero() return p def rs_square(p1, x, prec): """ Square the series modulo ``O(x**prec)`` Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_square >>> R, x = ring('x', QQ) >>> p = x**2 + 2*x + 1 >>> rs_square(p, x, 3) 6*x**2 + 4*x + 1 """ R = p1.ring p = R.zero iv = R.gens.index(x) get = p.get items = list(p1.items()) items.sort(key=lambda e: e[0][iv]) monomial_mul = R.monomial_mul for i in range(len(items)): exp1, v1 = items[i] for j in range(i): exp2, v2 = items[j] if exp1[iv] + exp2[iv] < prec: exp = monomial_mul(exp1, exp2) p[exp] = get(exp, 0) + v1*v2 else: break p = p.imul_num(2) get = p.get for expv, v in p1.items(): if 2*expv[iv] < prec: e2 = monomial_mul(expv, expv) p[e2] = get(e2, 0) + v**2 p.strip_zero() return p def rs_pow(p1, n, x, prec): """ Return ``p1**n`` modulo ``O(x**prec)`` Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_pow >>> R, x = ring('x', QQ) >>> p = x + 1 >>> rs_pow(p, 4, x, 3) 6*x**2 + 4*x + 1 """ R = p1.ring p = R.zero if isinstance(n, Rational): np = int(n.p) nq = int(n.q) if nq != 1: res = rs_nth_root(p1, nq, x, prec) if np != 1: res = rs_pow(res, np, x, prec) else: res = rs_pow(p1, np, x, prec) return res n = as_int(n) if n == 0: if p1: return R(1) else: raise ValueError('0**0 is undefined') if n < 0: p1 = rs_pow(p1, -n, x, prec) return rs_series_inversion(p1, x, prec) if n == 1: return rs_trunc(p1, x, prec) if n == 2: return rs_square(p1, x, prec) if n == 3: p2 = rs_square(p1, x, prec) return rs_mul(p1, p2, x, prec) p = R(1) while 1: if n & 1: p = rs_mul(p1, p, x, prec) n -= 1 if not n: break p1 = rs_square(p1, x, prec) n = n // 2 return p def rs_subs(p, rules, x, prec): """ Substitution with truncation according to the mapping in ``rules``. Return a series with precision ``prec`` in the generator ``x`` Note that substitutions are not done one after the other >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_subs >>> R, x, y = ring('x, y', QQ) >>> p = x**2 + y**2 >>> rs_subs(p, {x: x+ y, y: x+ 2*y}, x, 3) 2*x**2 + 6*x*y + 5*y**2 >>> (x + y)**2 + (x + 2*y)**2 2*x**2 + 6*x*y + 5*y**2 which differs from >>> rs_subs(rs_subs(p, {x: x+ y}, x, 3), {y: x+ 2*y}, x, 3) 5*x**2 + 12*x*y + 8*y**2 Parameters ---------- p : :class:`PolyElement` Input series. rules : :class:`dict` with substitution mappings. x : :class:`PolyElement` in which the series truncation is to be done. prec : :class:`Integer` order of the series after truncation. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_subs >>> R, x, y = ring('x, y', QQ) >>> rs_subs(x**2+y**2, {y: (x+y)**2}, x, 3) 6*x**2*y**2 + x**2 + 4*x*y**3 + y**4 """ R = p.ring ngens = R.ngens d = R(0) for i in range(ngens): d[(i, 1)] = R.gens[i] for var in rules: d[(R.index(var), 1)] = rules[var] p1 = R(0) p_keys = sorted(p.keys()) for expv in p_keys: p2 = R(1) for i in range(ngens): power = expv[i] if power == 0: continue if (i, power) not in d: q, r = divmod(power, 2) if r == 0 and (i, q) in d: d[(i, power)] = rs_square(d[(i, q)], x, prec) elif (i, power - 1) in d: d[(i, power)] = rs_mul(d[(i, power - 1)], d[(i, 1)], x, prec) else: d[(i, power)] = rs_pow(d[(i, 1)], power, x, prec) p2 = rs_mul(p2, d[(i, power)], x, prec) p1 += p2*p[expv] return p1 def _has_constant_term(p, x): """ Check if ``p`` has a constant term in ``x`` Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import _has_constant_term >>> R, x = ring('x', QQ) >>> p = x**2 + x + 1 >>> _has_constant_term(p, x) True """ R = p.ring iv = R.gens.index(x) zm = R.zero_monom a = [0]*R.ngens a[iv] = 1 miv = tuple(a) for expv in p: if monomial_min(expv, miv) == zm: return True return False def _get_constant_term(p, x): """Return constant term in p with respect to x Note that it is not simply `p[R.zero_monom]` as there might be multiple generators in the ring R. We want the `x`-free term which can contain other generators. """ R = p.ring zm = R.zero_monom i = R.gens.index(x) zm = R.zero_monom a = [0]*R.ngens a[i] = 1 miv = tuple(a) c = 0 for expv in p: if monomial_min(expv, miv) == zm: c += R({expv: p[expv]}) return c def _check_series_var(p, x, name): index = p.ring.gens.index(x) m = min(p, key=lambda k: k[index])[index] if m < 0: raise PoleError("Asymptotic expansion of %s around [oo] not " "implemented." % name) return index, m def _series_inversion1(p, x, prec): """ Univariate series inversion ``1/p`` modulo ``O(x**prec)``. The Newton method is used. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import _series_inversion1 >>> R, x = ring('x', QQ) >>> p = x + 1 >>> _series_inversion1(p, x, 4) -x**3 + x**2 - x + 1 """ if rs_is_puiseux(p, x): return rs_puiseux(_series_inversion1, p, x, prec) R = p.ring zm = R.zero_monom c = p[zm] # giant_steps does not seem to work with PythonRational numbers with 1 as # denominator. This makes sure such a number is converted to integer. if prec == int(prec): prec = int(prec) if zm not in p: raise ValueError("No constant term in series") if _has_constant_term(p - c, x): raise ValueError("p cannot contain a constant term depending on " "parameters") one = R(1) if R.domain is EX: one = 1 if c != one: # TODO add check that it is a unit p1 = R(1)/c else: p1 = R(1) for precx in _giant_steps(prec): t = 1 - rs_mul(p1, p, x, precx) p1 = p1 + rs_mul(p1, t, x, precx) return p1 def rs_series_inversion(p, x, prec): """ Multivariate series inversion ``1/p`` modulo ``O(x**prec)``. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_series_inversion >>> R, x, y = ring('x, y', QQ) >>> rs_series_inversion(1 + x*y**2, x, 4) -x**3*y**6 + x**2*y**4 - x*y**2 + 1 >>> rs_series_inversion(1 + x*y**2, y, 4) -x*y**2 + 1 >>> rs_series_inversion(x + x**2, x, 4) x**3 - x**2 + x - 1 + x**(-1) """ R = p.ring if p == R.zero: raise ZeroDivisionError zm = R.zero_monom index = R.gens.index(x) m = min(p, key=lambda k: k[index])[index] if m: p = mul_xin(p, index, -m) prec = prec + m if zm not in p: raise NotImplementedError("No constant term in series") if _has_constant_term(p - p[zm], x): raise NotImplementedError("p - p[0] must not have a constant term in " "the series variables") r = _series_inversion1(p, x, prec) if m != 0: r = mul_xin(r, index, -m) return r def _coefficient_t(p, t): r"""Coefficient of `x\_i**j` in p, where ``t`` = (i, j)""" i, j = t R = p.ring expv1 = [0]*R.ngens expv1[i] = j expv1 = tuple(expv1) p1 = R(0) for expv in p: if expv[i] == j: p1[monomial_div(expv, expv1)] = p[expv] return p1 def rs_series_reversion(p, x, n, y): r""" Reversion of a series. ``p`` is a series with ``O(x**n)`` of the form `p = a*x + f(x)` where `a` is a number different from 0. `f(x) = sum( a\_k*x\_k, k in range(2, n))` a_k : Can depend polynomially on other variables, not indicated. x : Variable with name x. y : Variable with name y. Solve `p = y`, that is, given `a*x + f(x) - y = 0`, find the solution x = r(y) up to O(y**n) Algorithm: If `r\_i` is the solution at order i, then: `a*r\_i + f(r\_i) - y = O(y**(i + 1))` and if r_(i + 1) is the solution at order i + 1, then: `a*r\_(i + 1) + f(r\_(i + 1)) - y = O(y**(i + 2))` We have, r_(i + 1) = r_i + e, such that, `a*e + f(r\_i) = O(y**(i + 2))` or `e = -f(r\_i)/a` So we use the recursion relation: `r\_(i + 1) = r\_i - f(r\_i)/a` with the boundary condition: `r\_1 = y` Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_series_reversion, rs_trunc >>> R, x, y, a, b = ring('x, y, a, b', QQ) >>> p = x - x**2 - 2*b*x**2 + 2*a*b*x**2 >>> p1 = rs_series_reversion(p, x, 3, y); p1 -2*y**2*a*b + 2*y**2*b + y**2 + y >>> rs_trunc(p.compose(x, p1), y, 3) y """ if rs_is_puiseux(p, x): raise NotImplementedError R = p.ring nx = R.gens.index(x) y = R(y) ny = R.gens.index(y) if _has_constant_term(p, x): raise ValueError("p must not contain a constant term in the series " "variable") a = _coefficient_t(p, (nx, 1)) zm = R.zero_monom assert zm in a and len(a) == 1 a = a[zm] r = y/a for i in range(2, n): sp = rs_subs(p, {x: r}, y, i + 1) sp = _coefficient_t(sp, (ny, i))*y**i r -= sp/a return r def rs_series_from_list(p, c, x, prec, concur=1): """ Return a series `sum c[n]*p**n` modulo `O(x**prec)`. It reduces the number of multiplications by summing concurrently. `ax = [1, p, p**2, .., p**(J - 1)]` `s = sum(c[i]*ax[i]` for i in `range(r, (r + 1)*J))*p**((K - 1)*J)` with `K >= (n + 1)/J` Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_series_from_list, rs_trunc >>> R, x = ring('x', QQ) >>> p = x**2 + x + 1 >>> c = [1, 2, 3] >>> rs_series_from_list(p, c, x, 4) 6*x**3 + 11*x**2 + 8*x + 6 >>> rs_trunc(1 + 2*p + 3*p**2, x, 4) 6*x**3 + 11*x**2 + 8*x + 6 >>> pc = R.from_list(list(reversed(c))) >>> rs_trunc(pc.compose(x, p), x, 4) 6*x**3 + 11*x**2 + 8*x + 6 See Also ======== sympy.polys.ring.compose """ R = p.ring n = len(c) if not concur: q = R(1) s = c[0]*q for i in range(1, n): q = rs_mul(q, p, x, prec) s += c[i]*q return s J = int(math.sqrt(n) + 1) K, r = divmod(n, J) if r: K += 1 ax = [R(1)] b = 1 q = R(1) if len(p) < 20: for i in range(1, J): q = rs_mul(q, p, x, prec) ax.append(q) else: for i in range(1, J): if i % 2 == 0: q = rs_square(ax[i//2], x, prec) else: q = rs_mul(q, p, x, prec) ax.append(q) # optimize using rs_square pj = rs_mul(ax[-1], p, x, prec) b = R(1) s = R(0) for k in range(K - 1): r = J*k s1 = c[r] for j in range(1, J): s1 += c[r + j]*ax[j] s1 = rs_mul(s1, b, x, prec) s += s1 b = rs_mul(b, pj, x, prec) if not b: break k = K - 1 r = J*k if r < n: s1 = c[r]*R(1) for j in range(1, J): if r + j >= n: break s1 += c[r + j]*ax[j] s1 = rs_mul(s1, b, x, prec) s += s1 return s def rs_diff(p, x): """ Return partial derivative of ``p`` with respect to ``x``. Parameters ========== x : :class:`PolyElement` with respect to which ``p`` is differentiated. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_diff >>> R, x, y = ring('x, y', QQ) >>> p = x + x**2*y**3 >>> rs_diff(p, x) 2*x*y**3 + 1 """ R = p.ring n = R.gens.index(x) p1 = R.zero mn = [0]*R.ngens mn[n] = 1 mn = tuple(mn) for expv in p: if expv[n]: e = monomial_ldiv(expv, mn) p1[e] = R.domain_new(p[expv]*expv[n]) return p1 def rs_integrate(p, x): """ Integrate ``p`` with respect to ``x``. Parameters ========== x : :class:`PolyElement` with respect to which ``p`` is integrated. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_integrate >>> R, x, y = ring('x, y', QQ) >>> p = x + x**2*y**3 >>> rs_integrate(p, x) 1/3*x**3*y**3 + 1/2*x**2 """ R = p.ring p1 = R.zero n = R.gens.index(x) mn = [0]*R.ngens mn[n] = 1 mn = tuple(mn) for expv in p: e = monomial_mul(expv, mn) p1[e] = R.domain_new(p[expv]/(expv[n] + 1)) return p1 def rs_fun(p, f, *args): r""" Function of a multivariate series computed by substitution. The case with f method name is used to compute `rs\_tan` and `rs\_nth\_root` of a multivariate series: `rs\_fun(p, tan, iv, prec)` tan series is first computed for a dummy variable _x, i.e, `rs\_tan(\_x, iv, prec)`. Then we substitute _x with p to get the desired series Parameters ========== p : :class:`PolyElement` The multivariate series to be expanded. f : `ring\_series` function to be applied on `p`. args[-2] : :class:`PolyElement` with respect to which, the series is to be expanded. args[-1] : Required order of the expanded series. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_fun, _tan1 >>> R, x, y = ring('x, y', QQ) >>> p = x + x*y + x**2*y + x**3*y**2 >>> rs_fun(p, _tan1, x, 4) 1/3*x**3*y**3 + 2*x**3*y**2 + x**3*y + 1/3*x**3 + x**2*y + x*y + x """ _R = p.ring R1, _x = ring('_x', _R.domain) h = int(args[-1]) args1 = args[:-2] + (_x, h) zm = _R.zero_monom # separate the constant term of the series # compute the univariate series f(_x, .., 'x', sum(nv)) if zm in p: x1 = _x + p[zm] p1 = p - p[zm] else: x1 = _x p1 = p if isinstance(f, str): q = getattr(x1, f)(*args1) else: q = f(x1, *args1) a = sorted(q.items()) c = [0]*h for x in a: c[x[0][0]] = x[1] p1 = rs_series_from_list(p1, c, args[-2], args[-1]) return p1 def mul_xin(p, i, n): r""" Return `p*x_i**n`. `x\_i` is the ith variable in ``p``. """ R = p.ring q = R(0) for k, v in p.items(): k1 = list(k) k1[i] += n q[tuple(k1)] = v return q def pow_xin(p, i, n): """ >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import pow_xin >>> R, x, y = ring('x, y', QQ) >>> p = x**QQ(2,5) + x + x**QQ(2,3) >>> index = p.ring.gens.index(x) >>> pow_xin(p, index, 15) x**15 + x**10 + x**6 """ R = p.ring q = R(0) for k, v in p.items(): k1 = list(k) k1[i] *= n q[tuple(k1)] = v return q def _nth_root1(p, n, x, prec): """ Univariate series expansion of the nth root of ``p``. The Newton method is used. """ if rs_is_puiseux(p, x): return rs_puiseux2(_nth_root1, p, n, x, prec) R = p.ring zm = R.zero_monom if zm not in p: raise NotImplementedError('No constant term in series') n = as_int(n) assert p[zm] == 1 p1 = R(1) if p == 1: return p if n == 0: return R(1) if n == 1: return p if n < 0: n = -n sign = 1 else: sign = 0 for precx in _giant_steps(prec): tmp = rs_pow(p1, n + 1, x, precx) tmp = rs_mul(tmp, p, x, precx) p1 += p1/n - tmp/n if sign: return p1 else: return _series_inversion1(p1, x, prec) def rs_nth_root(p, n, x, prec): """ Multivariate series expansion of the nth root of ``p``. Parameters ========== p : Expr The polynomial to computer the root of. n : integer The order of the root to be computed. x : :class:`PolyElement` prec : integer Order of the expanded series. Notes ===== The result of this function is dependent on the ring over which the polynomial has been defined. If the answer involves a root of a constant, make sure that the polynomial is over a real field. It can not yet handle roots of symbols. Examples ======== >>> from sympy.polys.domains import QQ, RR >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_nth_root >>> R, x, y = ring('x, y', QQ) >>> rs_nth_root(1 + x + x*y, -3, x, 3) 2/9*x**2*y**2 + 4/9*x**2*y + 2/9*x**2 - 1/3*x*y - 1/3*x + 1 >>> R, x, y = ring('x, y', RR) >>> rs_nth_root(3 + x + x*y, 3, x, 2) 0.160249952256379*x*y + 0.160249952256379*x + 1.44224957030741 """ p0 = p n0 = n if n == 0: if p == 0: raise ValueError('0**0 expression') else: return p.ring(1) if n == 1: return rs_trunc(p, x, prec) R = p.ring zm = R.zero_monom index = R.gens.index(x) m = min(p, key=lambda k: k[index])[index] p = mul_xin(p, index, -m) prec -= m if _has_constant_term(p - 1, x): zm = R.zero_monom c = p[zm] if R.domain is EX: c_expr = c.as_expr() const = c_expr**QQ(1, n) elif isinstance(c, PolyElement): try: c_expr = c.as_expr() const = R(c_expr**(QQ(1, n))) except ValueError: raise DomainError("The given series can't be expanded in " "this domain.") else: try: # RealElement doesn't support const = R(c**Rational(1, n)) # exponentiation with mpq object except ValueError: # as exponent raise DomainError("The given series can't be expanded in " "this domain.") res = rs_nth_root(p/c, n, x, prec)*const else: res = _nth_root1(p, n, x, prec) if m: m = QQ(m, n) res = mul_xin(res, index, m) return res def rs_log(p, x, prec): """ The Logarithm of ``p`` modulo ``O(x**prec)``. Notes ===== Truncation of ``integral dx p**-1*d p/dx`` is used. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_log >>> R, x = ring('x', QQ) >>> rs_log(1 + x, x, 8) 1/7*x**7 - 1/6*x**6 + 1/5*x**5 - 1/4*x**4 + 1/3*x**3 - 1/2*x**2 + x >>> rs_log(x**QQ(3, 2) + 1, x, 5) 1/3*x**(9/2) - 1/2*x**3 + x**(3/2) """ if rs_is_puiseux(p, x): return rs_puiseux(rs_log, p, x, prec) R = p.ring if p == 1: return R.zero c = _get_constant_term(p, x) if c: const = 0 if c == 1: pass else: c_expr = c.as_expr() if R.domain is EX: const = log(c_expr) elif isinstance(c, PolyElement): try: const = R(log(c_expr)) except ValueError: R = R.add_gens([log(c_expr)]) p = p.set_ring(R) x = x.set_ring(R) c = c.set_ring(R) const = R(log(c_expr)) else: try: const = R(log(c)) except ValueError: raise DomainError("The given series can't be expanded in " "this domain.") dlog = p.diff(x) dlog = rs_mul(dlog, _series_inversion1(p, x, prec), x, prec - 1) return rs_integrate(dlog, x) + const else: raise NotImplementedError def rs_LambertW(p, x, prec): """ Calculate the series expansion of the principal branch of the Lambert W function. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_LambertW >>> R, x, y = ring('x, y', QQ) >>> rs_LambertW(x + x*y, x, 3) -x**2*y**2 - 2*x**2*y - x**2 + x*y + x See Also ======== LambertW """ if rs_is_puiseux(p, x): return rs_puiseux(rs_LambertW, p, x, prec) R = p.ring p1 = R(0) if _has_constant_term(p, x): raise NotImplementedError("Polynomial must not have constant term in " "the series variables") if x in R.gens: for precx in _giant_steps(prec): e = rs_exp(p1, x, precx) p2 = rs_mul(e, p1, x, precx) - p p3 = rs_mul(e, p1 + 1, x, precx) p3 = rs_series_inversion(p3, x, precx) tmp = rs_mul(p2, p3, x, precx) p1 -= tmp return p1 else: raise NotImplementedError def _exp1(p, x, prec): r"""Helper function for `rs\_exp`. """ R = p.ring p1 = R(1) for precx in _giant_steps(prec): pt = p - rs_log(p1, x, precx) tmp = rs_mul(pt, p1, x, precx) p1 += tmp return p1 def rs_exp(p, x, prec): """ Exponentiation of a series modulo ``O(x**prec)`` Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_exp >>> R, x = ring('x', QQ) >>> rs_exp(x**2, x, 7) 1/6*x**6 + 1/2*x**4 + x**2 + 1 """ if rs_is_puiseux(p, x): return rs_puiseux(rs_exp, p, x, prec) R = p.ring c = _get_constant_term(p, x) if c: if R.domain is EX: c_expr = c.as_expr() const = exp(c_expr) elif isinstance(c, PolyElement): try: c_expr = c.as_expr() const = R(exp(c_expr)) except ValueError: R = R.add_gens([exp(c_expr)]) p = p.set_ring(R) x = x.set_ring(R) c = c.set_ring(R) const = R(exp(c_expr)) else: try: const = R(exp(c)) except ValueError: raise DomainError("The given series can't be expanded in " "this domain.") p1 = p - c # Makes use of sympy functions to evaluate the values of the cos/sin # of the constant term. return const*rs_exp(p1, x, prec) if len(p) > 20: return _exp1(p, x, prec) one = R(1) n = 1 k = 1 c = [] for k in range(prec): c.append(one/n) k += 1 n *= k r = rs_series_from_list(p, c, x, prec) return r def _atan(p, iv, prec): """ Expansion using formula. Faster on very small and univariate series. """ R = p.ring mo = R(-1) c = [-mo] p2 = rs_square(p, iv, prec) for k in range(1, prec): c.append(mo**k/(2*k + 1)) s = rs_series_from_list(p2, c, iv, prec) s = rs_mul(s, p, iv, prec) return s def rs_atan(p, x, prec): """ The arctangent of a series Return the series expansion of the atan of ``p``, about 0. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_atan >>> R, x, y = ring('x, y', QQ) >>> rs_atan(x + x*y, x, 4) -1/3*x**3*y**3 - x**3*y**2 - x**3*y - 1/3*x**3 + x*y + x See Also ======== atan """ if rs_is_puiseux(p, x): return rs_puiseux(rs_atan, p, x, prec) R = p.ring const = 0 if _has_constant_term(p, x): zm = R.zero_monom c = p[zm] if R.domain is EX: c_expr = c.as_expr() const = atan(c_expr) elif isinstance(c, PolyElement): try: c_expr = c.as_expr() const = R(atan(c_expr)) except ValueError: raise DomainError("The given series can't be expanded in " "this domain.") else: try: const = R(atan(c)) except ValueError: raise DomainError("The given series can't be expanded in " "this domain.") # Instead of using a closed form formula, we differentiate atan(p) to get # `1/(1+p**2) * dp`, whose series expansion is much easier to calculate. # Finally we integrate to get back atan dp = p.diff(x) p1 = rs_square(p, x, prec) + R(1) p1 = rs_series_inversion(p1, x, prec - 1) p1 = rs_mul(dp, p1, x, prec - 1) return rs_integrate(p1, x) + const def rs_asin(p, x, prec): """ Arcsine of a series Return the series expansion of the asin of ``p``, about 0. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_asin >>> R, x, y = ring('x, y', QQ) >>> rs_asin(x, x, 8) 5/112*x**7 + 3/40*x**5 + 1/6*x**3 + x See Also ======== asin """ if rs_is_puiseux(p, x): return rs_puiseux(rs_asin, p, x, prec) if _has_constant_term(p, x): raise NotImplementedError("Polynomial must not have constant term in " "series variables") R = p.ring if x in R.gens: # get a good value if len(p) > 20: dp = rs_diff(p, x) p1 = 1 - rs_square(p, x, prec - 1) p1 = rs_nth_root(p1, -2, x, prec - 1) p1 = rs_mul(dp, p1, x, prec - 1) return rs_integrate(p1, x) one = R(1) c = [0, one, 0] for k in range(3, prec, 2): c.append((k - 2)**2*c[-2]/(k*(k - 1))) c.append(0) return rs_series_from_list(p, c, x, prec) else: raise NotImplementedError def _tan1(p, x, prec): r""" Helper function of `rs\_tan`. Return the series expansion of tan of a univariate series using Newton's method. It takes advantage of the fact that series expansion of atan is easier than that of tan. Consider `f(x) = y - atan(x)` Let r be a root of f(x) found using Newton's method. Then `f(r) = 0` Or `y = atan(x)` where `x = tan(y)` as required. """ R = p.ring p1 = R(0) for precx in _giant_steps(prec): tmp = p - rs_atan(p1, x, precx) tmp = rs_mul(tmp, 1 + rs_square(p1, x, precx), x, precx) p1 += tmp return p1 def rs_tan(p, x, prec): """ Tangent of a series. Return the series expansion of the tan of ``p``, about 0. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_tan >>> R, x, y = ring('x, y', QQ) >>> rs_tan(x + x*y, x, 4) 1/3*x**3*y**3 + x**3*y**2 + x**3*y + 1/3*x**3 + x*y + x See Also ======== _tan1, tan """ if rs_is_puiseux(p, x): r = rs_puiseux(rs_tan, p, x, prec) return r R = p.ring const = 0 c = _get_constant_term(p, x) if c: if R.domain is EX: c_expr = c.as_expr() const = tan(c_expr) elif isinstance(c, PolyElement): try: c_expr = c.as_expr() const = R(tan(c_expr)) except ValueError: R = R.add_gens([tan(c_expr, )]) p = p.set_ring(R) x = x.set_ring(R) c = c.set_ring(R) const = R(tan(c_expr)) else: try: const = R(tan(c)) except ValueError: raise DomainError("The given series can't be expanded in " "this domain.") p1 = p - c # Makes use of sympy functions to evaluate the values of the cos/sin # of the constant term. t2 = rs_tan(p1, x, prec) t = rs_series_inversion(1 - const*t2, x, prec) return rs_mul(const + t2, t, x, prec) if R.ngens == 1: return _tan1(p, x, prec) else: return rs_fun(p, rs_tan, x, prec) def rs_cot(p, x, prec): """ Cotangent of a series Return the series expansion of the cot of ``p``, about 0. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_cot >>> R, x, y = ring('x, y', QQ) >>> rs_cot(x, x, 6) -2/945*x**5 - 1/45*x**3 - 1/3*x + x**(-1) See Also ======== cot """ # It can not handle series like `p = x + x*y` where the coefficient of the # linear term in the series variable is symbolic. if rs_is_puiseux(p, x): r = rs_puiseux(rs_cot, p, x, prec) return r i, m = _check_series_var(p, x, 'cot') prec1 = prec + 2*m c, s = rs_cos_sin(p, x, prec1) s = mul_xin(s, i, -m) s = rs_series_inversion(s, x, prec1) res = rs_mul(c, s, x, prec1) res = mul_xin(res, i, -m) res = rs_trunc(res, x, prec) return res def rs_sin(p, x, prec): """ Sine of a series Return the series expansion of the sin of ``p``, about 0. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_sin >>> R, x, y = ring('x, y', QQ) >>> rs_sin(x + x*y, x, 4) -1/6*x**3*y**3 - 1/2*x**3*y**2 - 1/2*x**3*y - 1/6*x**3 + x*y + x >>> rs_sin(x**QQ(3, 2) + x*y**QQ(7, 5), x, 4) -1/2*x**(7/2)*y**(14/5) - 1/6*x**3*y**(21/5) + x**(3/2) + x*y**(7/5) See Also ======== sin """ if rs_is_puiseux(p, x): return rs_puiseux(rs_sin, p, x, prec) R = x.ring if not p: return R(0) c = _get_constant_term(p, x) if c: if R.domain is EX: c_expr = c.as_expr() t1, t2 = sin(c_expr), cos(c_expr) elif isinstance(c, PolyElement): try: c_expr = c.as_expr() t1, t2 = R(sin(c_expr)), R(cos(c_expr)) except ValueError: R = R.add_gens([sin(c_expr), cos(c_expr)]) p = p.set_ring(R) x = x.set_ring(R) c = c.set_ring(R) t1, t2 = R(sin(c_expr)), R(cos(c_expr)) else: try: t1, t2 = R(sin(c)), R(cos(c)) except ValueError: raise DomainError("The given series can't be expanded in " "this domain.") p1 = p - c # Makes use of sympy cos, sin functions to evaluate the values of the # cos/sin of the constant term. return rs_sin(p1, x, prec)*t2 + rs_cos(p1, x, prec)*t1 # Series is calculated in terms of tan as its evaluation is fast. if len(p) > 20 and R.ngens == 1: t = rs_tan(p/2, x, prec) t2 = rs_square(t, x, prec) p1 = rs_series_inversion(1 + t2, x, prec) return rs_mul(p1, 2*t, x, prec) one = R(1) n = 1 c = [0] for k in range(2, prec + 2, 2): c.append(one/n) c.append(0) n *= -k*(k + 1) return rs_series_from_list(p, c, x, prec) def rs_cos(p, x, prec): """ Cosine of a series Return the series expansion of the cos of ``p``, about 0. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_cos >>> R, x, y = ring('x, y', QQ) >>> rs_cos(x + x*y, x, 4) -1/2*x**2*y**2 - x**2*y - 1/2*x**2 + 1 >>> rs_cos(x + x*y, x, 4)/x**QQ(7, 5) -1/2*x**(3/5)*y**2 - x**(3/5)*y - 1/2*x**(3/5) + x**(-7/5) See Also ======== cos """ if rs_is_puiseux(p, x): return rs_puiseux(rs_cos, p, x, prec) R = p.ring c = _get_constant_term(p, x) if c: if R.domain is EX: c_expr = c.as_expr() t1, t2 = sin(c_expr), cos(c_expr) elif isinstance(c, PolyElement): try: c_expr = c.as_expr() t1, t2 = R(sin(c_expr)), R(cos(c_expr)) except ValueError: R = R.add_gens([sin(c_expr), cos(c_expr)]) p = p.set_ring(R) x = x.set_ring(R) c = c.set_ring(R) else: try: t1, t2 = R(sin(c)), R(cos(c)) except ValueError: raise DomainError("The given series can't be expanded in " "this domain.") p1 = p - c # Makes use of sympy cos, sin functions to evaluate the values of the # cos/sin of the constant term. p_cos = rs_cos(p1, x, prec) p_sin = rs_sin(p1, x, prec) R = R.compose(p_cos.ring).compose(p_sin.ring) p_cos.set_ring(R) p_sin.set_ring(R) t1, t2 = R(sin(c_expr)), R(cos(c_expr)) return p_cos*t2 - p_sin*t1 # Series is calculated in terms of tan as its evaluation is fast. if len(p) > 20 and R.ngens == 1: t = rs_tan(p/2, x, prec) t2 = rs_square(t, x, prec) p1 = rs_series_inversion(1+t2, x, prec) return rs_mul(p1, 1 - t2, x, prec) one = R(1) n = 1 c = [] for k in range(2, prec + 2, 2): c.append(one/n) c.append(0) n *= -k*(k - 1) return rs_series_from_list(p, c, x, prec) def rs_cos_sin(p, x, prec): r""" Return the tuple `(rs\_cos(p, x, prec)`, `rs\_sin(p, x, prec))`. Is faster than calling rs_cos and rs_sin separately """ if rs_is_puiseux(p, x): return rs_puiseux(rs_cos_sin, p, x, prec) t = rs_tan(p/2, x, prec) t2 = rs_square(t, x, prec) p1 = rs_series_inversion(1 + t2, x, prec) return (rs_mul(p1, 1 - t2, x, prec), rs_mul(p1, 2*t, x, prec)) def _atanh(p, x, prec): """ Expansion using formula Faster for very small and univariate series """ R = p.ring one = R(1) c = [one] p2 = rs_square(p, x, prec) for k in range(1, prec): c.append(one/(2*k + 1)) s = rs_series_from_list(p2, c, x, prec) s = rs_mul(s, p, x, prec) return s def rs_atanh(p, x, prec): """ Hyperbolic arctangent of a series Return the series expansion of the atanh of ``p``, about 0. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_atanh >>> R, x, y = ring('x, y', QQ) >>> rs_atanh(x + x*y, x, 4) 1/3*x**3*y**3 + x**3*y**2 + x**3*y + 1/3*x**3 + x*y + x See Also ======== atanh """ if rs_is_puiseux(p, x): return rs_puiseux(rs_atanh, p, x, prec) R = p.ring const = 0 if _has_constant_term(p, x): zm = R.zero_monom c = p[zm] if R.domain is EX: c_expr = c.as_expr() const = atanh(c_expr) elif isinstance(c, PolyElement): try: c_expr = c.as_expr() const = R(atanh(c_expr)) except ValueError: raise DomainError("The given series can't be expanded in " "this domain.") else: try: const = R(atanh(c)) except ValueError: raise DomainError("The given series can't be expanded in " "this domain.") # Instead of using a closed form formula, we differentiate atanh(p) to get # `1/(1-p**2) * dp`, whose series expansion is much easier to calculate. # Finally we integrate to get back atanh dp = rs_diff(p, x) p1 = - rs_square(p, x, prec) + 1 p1 = rs_series_inversion(p1, x, prec - 1) p1 = rs_mul(dp, p1, x, prec - 1) return rs_integrate(p1, x) + const def rs_sinh(p, x, prec): """ Hyperbolic sine of a series Return the series expansion of the sinh of ``p``, about 0. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_sinh >>> R, x, y = ring('x, y', QQ) >>> rs_sinh(x + x*y, x, 4) 1/6*x**3*y**3 + 1/2*x**3*y**2 + 1/2*x**3*y + 1/6*x**3 + x*y + x See Also ======== sinh """ if rs_is_puiseux(p, x): return rs_puiseux(rs_sinh, p, x, prec) t = rs_exp(p, x, prec) t1 = rs_series_inversion(t, x, prec) return (t - t1)/2 def rs_cosh(p, x, prec): """ Hyperbolic cosine of a series Return the series expansion of the cosh of ``p``, about 0. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_cosh >>> R, x, y = ring('x, y', QQ) >>> rs_cosh(x + x*y, x, 4) 1/2*x**2*y**2 + x**2*y + 1/2*x**2 + 1 See Also ======== cosh """ if rs_is_puiseux(p, x): return rs_puiseux(rs_cosh, p, x, prec) t = rs_exp(p, x, prec) t1 = rs_series_inversion(t, x, prec) return (t + t1)/2 def _tanh(p, x, prec): r""" Helper function of `rs\_tanh` Return the series expansion of tanh of a univariate series using Newton's method. It takes advantage of the fact that series expansion of atanh is easier than that of tanh. See Also ======== _tanh """ R = p.ring p1 = R(0) for precx in _giant_steps(prec): tmp = p - rs_atanh(p1, x, precx) tmp = rs_mul(tmp, 1 - rs_square(p1, x, prec), x, precx) p1 += tmp return p1 def rs_tanh(p, x, prec): """ Hyperbolic tangent of a series Return the series expansion of the tanh of ``p``, about 0. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_tanh >>> R, x, y = ring('x, y', QQ) >>> rs_tanh(x + x*y, x, 4) -1/3*x**3*y**3 - x**3*y**2 - x**3*y - 1/3*x**3 + x*y + x See Also ======== tanh """ if rs_is_puiseux(p, x): return rs_puiseux(rs_tanh, p, x, prec) R = p.ring const = 0 if _has_constant_term(p, x): zm = R.zero_monom c = p[zm] if R.domain is EX: c_expr = c.as_expr() const = tanh(c_expr) elif isinstance(c, PolyElement): try: c_expr = c.as_expr() const = R(tanh(c_expr)) except ValueError: raise DomainError("The given series can't be expanded in " "this domain.") else: try: const = R(tanh(c)) except ValueError: raise DomainError("The given series can't be expanded in " "this domain.") p1 = p - c t1 = rs_tanh(p1, x, prec) t = rs_series_inversion(1 + const*t1, x, prec) return rs_mul(const + t1, t, x, prec) if R.ngens == 1: return _tanh(p, x, prec) else: return rs_fun(p, _tanh, x, prec) def rs_newton(p, x, prec): """ Compute the truncated Newton sum of the polynomial ``p`` Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_newton >>> R, x = ring('x', QQ) >>> p = x**2 - 2 >>> rs_newton(p, x, 5) 8*x**4 + 4*x**2 + 2 """ deg = p.degree() p1 = _invert_monoms(p) p2 = rs_series_inversion(p1, x, prec) p3 = rs_mul(p1.diff(x), p2, x, prec) res = deg - p3*x return res def rs_hadamard_exp(p1, inverse=False): """ Return ``sum f_i/i!*x**i`` from ``sum f_i*x**i``, where ``x`` is the first variable. If ``invers=True`` return ``sum f_i*i!*x**i`` Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_hadamard_exp >>> R, x = ring('x', QQ) >>> p = 1 + x + x**2 + x**3 >>> rs_hadamard_exp(p) 1/6*x**3 + 1/2*x**2 + x + 1 """ R = p1.ring if R.domain != QQ: raise NotImplementedError p = R.zero if not inverse: for exp1, v1 in p1.items(): p[exp1] = v1/int(ifac(exp1[0])) else: for exp1, v1 in p1.items(): p[exp1] = v1*int(ifac(exp1[0])) return p def rs_compose_add(p1, p2): """ compute the composed sum ``prod(p2(x - beta) for beta root of p1)`` Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> from sympy.polys.ring_series import rs_compose_add >>> R, x = ring('x', QQ) >>> f = x**2 - 2 >>> g = x**2 - 3 >>> rs_compose_add(f, g) x**4 - 10*x**2 + 1 References ========== .. [1] A. Bostan, P. Flajolet, B. Salvy and E. Schost "Fast Computation with Two Algebraic Numbers", (2002) Research Report 4579, Institut National de Recherche en Informatique et en Automatique """ R = p1.ring x = R.gens[0] prec = p1.degree() * p2.degree() + 1 np1 = rs_newton(p1, x, prec) np1e = rs_hadamard_exp(np1) np2 = rs_newton(p2, x, prec) np2e = rs_hadamard_exp(np2) np3e = rs_mul(np1e, np2e, x, prec) np3 = rs_hadamard_exp(np3e, True) np3a = (np3[(0,)] - np3)/x q = rs_integrate(np3a, x) q = rs_exp(q, x, prec) q = _invert_monoms(q) q = q.primitive()[1] dp = p1.degree() * p2.degree() - q.degree() # `dp` is the multiplicity of the zeroes of the resultant; # these zeroes are missed in this computation so they are put here. # if p1 and p2 are monic irreducible polynomials, # there are zeroes in the resultant # if and only if p1 = p2 ; in fact in that case p1 and p2 have a # root in common, so gcd(p1, p2) != 1; being p1 and p2 irreducible # this means p1 = p2 if dp: q = q*x**dp return q _convert_func = { 'sin': 'rs_sin', 'cos': 'rs_cos', 'exp': 'rs_exp', 'tan': 'rs_tan', 'log': 'rs_log' } def rs_min_pow(expr, series_rs, a): """Find the minimum power of `a` in the series expansion of expr""" series = 0 n = 2 while series == 0: series = _rs_series(expr, series_rs, a, n) n *= 2 R = series.ring a = R(a) i = R.gens.index(a) return min(series, key=lambda t: t[i])[i] def _rs_series(expr, series_rs, a, prec): # TODO Use _parallel_dict_from_expr instead of sring as sring is # inefficient. For details, read the todo in sring. args = expr.args R = series_rs.ring # expr does not contain any function to be expanded if not any(arg.has(Function) for arg in args) and not expr.is_Function: return series_rs if not expr.has(a): return series_rs elif expr.is_Function: arg = args[0] if len(args) > 1: raise NotImplementedError R1, series = sring(arg, domain=QQ, expand=False, series=True) series_inner = _rs_series(arg, series, a, prec) # Why do we need to compose these three rings? # # We want to use a simple domain (like ``QQ`` or ``RR``) but they don't # support symbolic coefficients. We need a ring that for example lets # us have `sin(1)` and `cos(1)` as coefficients if we are expanding # `sin(x + 1)`. The ``EX`` domain allows all symbolic coefficients, but # that makes it very complex and hence slow. # # To solve this problem, we add only those symbolic elements as # generators to our ring, that we need. Here, series_inner might # involve terms like `sin(4)`, `exp(a)`, etc, which are not there in # R1 or R. Hence, we compose these three rings to create one that has # the generators of all three. R = R.compose(R1).compose(series_inner.ring) series_inner = series_inner.set_ring(R) series = eval(_convert_func[str(expr.func)])(series_inner, R(a), prec) return series elif expr.is_Mul: n = len(args) for arg in args: # XXX Looks redundant if not arg.is_Number: R1, _ = sring(arg, expand=False, series=True) R = R.compose(R1) min_pows = list(map(rs_min_pow, args, [R(arg) for arg in args], [a]*len(args))) sum_pows = sum(min_pows) series = R(1) for i in range(n): _series = _rs_series(args[i], R(args[i]), a, prec - sum_pows + min_pows[i]) R = R.compose(_series.ring) _series = _series.set_ring(R) series = series.set_ring(R) series *= _series series = rs_trunc(series, R(a), prec) return series elif expr.is_Add: n = len(args) series = R(0) for i in range(n): _series = _rs_series(args[i], R(args[i]), a, prec) R = R.compose(_series.ring) _series = _series.set_ring(R) series = series.set_ring(R) series += _series return series elif expr.is_Pow: R1, _ = sring(expr.base, domain=QQ, expand=False, series=True) R = R.compose(R1) series_inner = _rs_series(expr.base, R(expr.base), a, prec) return rs_pow(series_inner, expr.exp, series_inner.ring(a), prec) # The `is_constant` method is buggy hence we check it at the end. # See issue #9786 for details. elif isinstance(expr, Expr) and expr.is_constant(): return sring(expr, domain=QQ, expand=False, series=True)[1] else: raise NotImplementedError def rs_series(expr, a, prec): """Return the series expansion of an expression about 0. Parameters ========== expr : :class:`Expr` a : :class:`Symbol` with respect to which expr is to be expanded prec : order of the series expansion Currently supports multivariate Taylor series expansion. This is much faster that Sympy's series method as it uses sparse polynomial operations. It automatically creates the simplest ring required to represent the series expansion through repeated calls to sring. Examples ======== >>> from sympy.polys.ring_series import rs_series >>> from sympy.functions import sin, cos, exp, tan >>> from sympy.core import symbols >>> from sympy.polys.domains import QQ >>> a, b, c = symbols('a, b, c') >>> rs_series(sin(a) + exp(a), a, 5) 1/24*a**4 + 1/2*a**2 + 2*a + 1 >>> series = rs_series(tan(a + b)*cos(a + c), a, 2) >>> series.as_expr() -a*sin(c)*tan(b) + a*cos(c)*tan(b)**2 + a*cos(c) + cos(c)*tan(b) >>> series = rs_series(exp(a**QQ(1,3) + a**QQ(2, 5)), a, 1) >>> series.as_expr() a**(11/15) + a**(4/5)/2 + a**(2/5) + a**(2/3)/2 + a**(1/3) + 1 """ R, series = sring(expr, domain=QQ, expand=False, series=True) if a not in R.symbols: R = R.add_gens([a, ]) series = series.set_ring(R) series = _rs_series(expr, series, a, prec) R = series.ring gen = R(a) prec_got = series.degree(gen) + 1 if prec_got >= prec: return rs_trunc(series, gen, prec) else: # increase the requested number of terms to get the desired # number keep increasing (up to 9) until the received order # is different than the original order and then predict how # many additional terms are needed for more in range(1, 9): p1 = _rs_series(expr, series, a, prec=prec + more) gen = gen.set_ring(p1.ring) new_prec = p1.degree(gen) + 1 if new_prec != prec_got: prec_do = ceiling(prec + (prec - prec_got)*more/(new_prec - prec_got)) p1 = _rs_series(expr, series, a, prec=prec_do) while p1.degree(gen) + 1 < prec: p1 = _rs_series(expr, series, a, prec=prec_do) gen = gen.set_ring(p1.ring) prec_do *= 2 break else: break else: raise ValueError('Could not calculate %s terms for %s' % (str(prec), expr)) return rs_trunc(p1, gen, prec)

25e18d77ab511aafe67c1c345be29b44d680a7321461afdc68626bbeda3283ea

"""OO layer for several polynomial representations. """ from __future__ import print_function, division from sympy import oo from sympy.core.sympify import CantSympify from sympy.polys.polyerrors import CoercionFailed, NotReversible, NotInvertible from sympy.polys.polyutils import PicklableWithSlots class GenericPoly(PicklableWithSlots): """Base class for low-level polynomial representations. """ def ground_to_ring(f): """Make the ground domain a ring. """ return f.set_domain(f.dom.get_ring()) def ground_to_field(f): """Make the ground domain a field. """ return f.set_domain(f.dom.get_field()) def ground_to_exact(f): """Make the ground domain exact. """ return f.set_domain(f.dom.get_exact()) @classmethod def _perify_factors(per, result, include): if include: coeff, factors = result else: coeff = result factors = [ (per(g), k) for g, k in factors ] if include: return coeff, factors else: return factors from sympy.polys.densebasic import ( dmp_validate, dup_normal, dmp_normal, dup_convert, dmp_convert, dmp_from_sympy, dup_strip, dup_degree, dmp_degree_in, dmp_degree_list, dmp_negative_p, dup_LC, dmp_ground_LC, dup_TC, dmp_ground_TC, dmp_ground_nth, dmp_one, dmp_ground, dmp_zero_p, dmp_one_p, dmp_ground_p, dup_from_dict, dmp_from_dict, dmp_to_dict, dmp_deflate, dmp_inject, dmp_eject, dmp_terms_gcd, dmp_list_terms, dmp_exclude, dmp_slice_in, dmp_permute, dmp_to_tuple,) from sympy.polys.densearith import ( dmp_add_ground, dmp_sub_ground, dmp_mul_ground, dmp_quo_ground, dmp_exquo_ground, dmp_abs, dup_neg, dmp_neg, dup_add, dmp_add, dup_sub, dmp_sub, dup_mul, dmp_mul, dmp_sqr, dup_pow, dmp_pow, dmp_pdiv, dmp_prem, dmp_pquo, dmp_pexquo, dmp_div, dup_rem, dmp_rem, dmp_quo, dmp_exquo, dmp_add_mul, dmp_sub_mul, dmp_max_norm, dmp_l1_norm) from sympy.polys.densetools import ( dmp_clear_denoms, dmp_integrate_in, dmp_diff_in, dmp_eval_in, dup_revert, dmp_ground_trunc, dmp_ground_content, dmp_ground_primitive, dmp_ground_monic, dmp_compose, dup_decompose, dup_shift, dup_transform, dmp_lift) from sympy.polys.euclidtools import ( dup_half_gcdex, dup_gcdex, dup_invert, dmp_subresultants, dmp_resultant, dmp_discriminant, dmp_inner_gcd, dmp_gcd, dmp_lcm, dmp_cancel) from sympy.polys.sqfreetools import ( dup_gff_list, dmp_norm, dmp_sqf_p, dmp_sqf_norm, dmp_sqf_part, dmp_sqf_list, dmp_sqf_list_include) from sympy.polys.factortools import ( dup_cyclotomic_p, dmp_irreducible_p, dmp_factor_list, dmp_factor_list_include) from sympy.polys.rootisolation import ( dup_isolate_real_roots_sqf, dup_isolate_real_roots, dup_isolate_all_roots_sqf, dup_isolate_all_roots, dup_refine_real_root, dup_count_real_roots, dup_count_complex_roots, dup_sturm) from sympy.polys.polyerrors import ( UnificationFailed, PolynomialError) def init_normal_DMP(rep, lev, dom): return DMP(dmp_normal(rep, lev, dom), dom, lev) class DMP(PicklableWithSlots, CantSympify): """Dense Multivariate Polynomials over `K`. """ __slots__ = ['rep', 'lev', 'dom', 'ring'] def __init__(self, rep, dom, lev=None, ring=None): if lev is not None: if type(rep) is dict: rep = dmp_from_dict(rep, lev, dom) elif type(rep) is not list: rep = dmp_ground(dom.convert(rep), lev) else: rep, lev = dmp_validate(rep) self.rep = rep self.lev = lev self.dom = dom self.ring = ring def __repr__(f): return "%s(%s, %s, %s)" % (f.__class__.__name__, f.rep, f.dom, f.ring) def __hash__(f): return hash((f.__class__.__name__, f.to_tuple(), f.lev, f.dom, f.ring)) def unify(f, g): """Unify representations of two multivariate polynomials. """ if not isinstance(g, DMP) or f.lev != g.lev: raise UnificationFailed("can't unify %s with %s" % (f, g)) if f.dom == g.dom and f.ring == g.ring: return f.lev, f.dom, f.per, f.rep, g.rep else: lev, dom = f.lev, f.dom.unify(g.dom) ring = f.ring if g.ring is not None: if ring is not None: ring = ring.unify(g.ring) else: ring = g.ring F = dmp_convert(f.rep, lev, f.dom, dom) G = dmp_convert(g.rep, lev, g.dom, dom) def per(rep, dom=dom, lev=lev, kill=False): if kill: if not lev: return rep else: lev -= 1 return DMP(rep, dom, lev, ring) return lev, dom, per, F, G def per(f, rep, dom=None, kill=False, ring=None): """Create a DMP out of the given representation. """ lev = f.lev if kill: if not lev: return rep else: lev -= 1 if dom is None: dom = f.dom if ring is None: ring = f.ring return DMP(rep, dom, lev, ring) @classmethod def zero(cls, lev, dom, ring=None): return DMP(0, dom, lev, ring) @classmethod def one(cls, lev, dom, ring=None): return DMP(1, dom, lev, ring) @classmethod def from_list(cls, rep, lev, dom): """Create an instance of ``cls`` given a list of native coefficients. """ return cls(dmp_convert(rep, lev, None, dom), dom, lev) @classmethod def from_sympy_list(cls, rep, lev, dom): """Create an instance of ``cls`` given a list of SymPy coefficients. """ return cls(dmp_from_sympy(rep, lev, dom), dom, lev) def to_dict(f, zero=False): """Convert ``f`` to a dict representation with native coefficients. """ return dmp_to_dict(f.rep, f.lev, f.dom, zero=zero) def to_sympy_dict(f, zero=False): """Convert ``f`` to a dict representation with SymPy coefficients. """ rep = dmp_to_dict(f.rep, f.lev, f.dom, zero=zero) for k, v in rep.items(): rep[k] = f.dom.to_sympy(v) return rep def to_list(f): """Convert ``f`` to a list representation with native coefficients. """ return f.rep def to_sympy_list(f): """Convert ``f`` to a list representation with SymPy coefficients. """ def sympify_nested_list(rep): out = [] for val in rep: if isinstance(val, list): out.append(sympify_nested_list(val)) else: out.append(f.dom.to_sympy(val)) return out return sympify_nested_list(f.rep) def to_tuple(f): """ Convert ``f`` to a tuple representation with native coefficients. This is needed for hashing. """ return dmp_to_tuple(f.rep, f.lev) @classmethod def from_dict(cls, rep, lev, dom): """Construct and instance of ``cls`` from a ``dict`` representation. """ return cls(dmp_from_dict(rep, lev, dom), dom, lev) @classmethod def from_monoms_coeffs(cls, monoms, coeffs, lev, dom, ring=None): return DMP(dict(list(zip(monoms, coeffs))), dom, lev, ring) def to_ring(f): """Make the ground domain a ring. """ return f.convert(f.dom.get_ring()) def to_field(f): """Make the ground domain a field. """ return f.convert(f.dom.get_field()) def to_exact(f): """Make the ground domain exact. """ return f.convert(f.dom.get_exact()) def convert(f, dom): """Convert the ground domain of ``f``. """ if f.dom == dom: return f else: return DMP(dmp_convert(f.rep, f.lev, f.dom, dom), dom, f.lev) def slice(f, m, n, j=0): """Take a continuous subsequence of terms of ``f``. """ return f.per(dmp_slice_in(f.rep, m, n, j, f.lev, f.dom)) def coeffs(f, order=None): """Returns all non-zero coefficients from ``f`` in lex order. """ return [ c for _, c in dmp_list_terms(f.rep, f.lev, f.dom, order=order) ] def monoms(f, order=None): """Returns all non-zero monomials from ``f`` in lex order. """ return [ m for m, _ in dmp_list_terms(f.rep, f.lev, f.dom, order=order) ] def terms(f, order=None): """Returns all non-zero terms from ``f`` in lex order. """ return dmp_list_terms(f.rep, f.lev, f.dom, order=order) def all_coeffs(f): """Returns all coefficients from ``f``. """ if not f.lev: if not f: return [f.dom.zero] else: return [ c for c in f.rep ] else: raise PolynomialError('multivariate polynomials not supported') def all_monoms(f): """Returns all monomials from ``f``. """ if not f.lev: n = dup_degree(f.rep) if n < 0: return [(0,)] else: return [ (n - i,) for i, c in enumerate(f.rep) ] else: raise PolynomialError('multivariate polynomials not supported') def all_terms(f): """Returns all terms from a ``f``. """ if not f.lev: n = dup_degree(f.rep) if n < 0: return [((0,), f.dom.zero)] else: return [ ((n - i,), c) for i, c in enumerate(f.rep) ] else: raise PolynomialError('multivariate polynomials not supported') def lift(f): """Convert algebraic coefficients to rationals. """ return f.per(dmp_lift(f.rep, f.lev, f.dom), dom=f.dom.dom) def deflate(f): """Reduce degree of `f` by mapping `x_i^m` to `y_i`. """ J, F = dmp_deflate(f.rep, f.lev, f.dom) return J, f.per(F) def inject(f, front=False): """Inject ground domain generators into ``f``. """ F, lev = dmp_inject(f.rep, f.lev, f.dom, front=front) return f.__class__(F, f.dom.dom, lev) def eject(f, dom, front=False): """Eject selected generators into the ground domain. """ F = dmp_eject(f.rep, f.lev, dom, front=front) return f.__class__(F, dom, f.lev - len(dom.symbols)) def exclude(f): r""" Remove useless generators from ``f``. Returns the removed generators and the new excluded ``f``. Examples ======== >>> from sympy.polys.polyclasses import DMP >>> from sympy.polys.domains import ZZ >>> DMP([[[ZZ(1)]], [[ZZ(1)], [ZZ(2)]]], ZZ).exclude() ([2], DMP([[1], [1, 2]], ZZ, None)) """ J, F, u = dmp_exclude(f.rep, f.lev, f.dom) return J, f.__class__(F, f.dom, u) def permute(f, P): r""" Returns a polynomial in `K[x_{P(1)}, ..., x_{P(n)}]`. Examples ======== >>> from sympy.polys.polyclasses import DMP >>> from sympy.polys.domains import ZZ >>> DMP([[[ZZ(2)], [ZZ(1), ZZ(0)]], [[]]], ZZ).permute([1, 0, 2]) DMP([[[2], []], [[1, 0], []]], ZZ, None) >>> DMP([[[ZZ(2)], [ZZ(1), ZZ(0)]], [[]]], ZZ).permute([1, 2, 0]) DMP([[[1], []], [[2, 0], []]], ZZ, None) """ return f.per(dmp_permute(f.rep, P, f.lev, f.dom)) def terms_gcd(f): """Remove GCD of terms from the polynomial ``f``. """ J, F = dmp_terms_gcd(f.rep, f.lev, f.dom) return J, f.per(F) def add_ground(f, c): """Add an element of the ground domain to ``f``. """ return f.per(dmp_add_ground(f.rep, f.dom.convert(c), f.lev, f.dom)) def sub_ground(f, c): """Subtract an element of the ground domain from ``f``. """ return f.per(dmp_sub_ground(f.rep, f.dom.convert(c), f.lev, f.dom)) def mul_ground(f, c): """Multiply ``f`` by a an element of the ground domain. """ return f.per(dmp_mul_ground(f.rep, f.dom.convert(c), f.lev, f.dom)) def quo_ground(f, c): """Quotient of ``f`` by a an element of the ground domain. """ return f.per(dmp_quo_ground(f.rep, f.dom.convert(c), f.lev, f.dom)) def exquo_ground(f, c): """Exact quotient of ``f`` by a an element of the ground domain. """ return f.per(dmp_exquo_ground(f.rep, f.dom.convert(c), f.lev, f.dom)) def abs(f): """Make all coefficients in ``f`` positive. """ return f.per(dmp_abs(f.rep, f.lev, f.dom)) def neg(f): """Negate all coefficients in ``f``. """ return f.per(dmp_neg(f.rep, f.lev, f.dom)) def add(f, g): """Add two multivariate polynomials ``f`` and ``g``. """ lev, dom, per, F, G = f.unify(g) return per(dmp_add(F, G, lev, dom)) def sub(f, g): """Subtract two multivariate polynomials ``f`` and ``g``. """ lev, dom, per, F, G = f.unify(g) return per(dmp_sub(F, G, lev, dom)) def mul(f, g): """Multiply two multivariate polynomials ``f`` and ``g``. """ lev, dom, per, F, G = f.unify(g) return per(dmp_mul(F, G, lev, dom)) def sqr(f): """Square a multivariate polynomial ``f``. """ return f.per(dmp_sqr(f.rep, f.lev, f.dom)) def pow(f, n): """Raise ``f`` to a non-negative power ``n``. """ if isinstance(n, int): return f.per(dmp_pow(f.rep, n, f.lev, f.dom)) else: raise TypeError("``int`` expected, got %s" % type(n)) def pdiv(f, g): """Polynomial pseudo-division of ``f`` and ``g``. """ lev, dom, per, F, G = f.unify(g) q, r = dmp_pdiv(F, G, lev, dom) return per(q), per(r) def prem(f, g): """Polynomial pseudo-remainder of ``f`` and ``g``. """ lev, dom, per, F, G = f.unify(g) return per(dmp_prem(F, G, lev, dom)) def pquo(f, g): """Polynomial pseudo-quotient of ``f`` and ``g``. """ lev, dom, per, F, G = f.unify(g) return per(dmp_pquo(F, G, lev, dom)) def pexquo(f, g): """Polynomial exact pseudo-quotient of ``f`` and ``g``. """ lev, dom, per, F, G = f.unify(g) return per(dmp_pexquo(F, G, lev, dom)) def div(f, g): """Polynomial division with remainder of ``f`` and ``g``. """ lev, dom, per, F, G = f.unify(g) q, r = dmp_div(F, G, lev, dom) return per(q), per(r) def rem(f, g): """Computes polynomial remainder of ``f`` and ``g``. """ lev, dom, per, F, G = f.unify(g) return per(dmp_rem(F, G, lev, dom)) def quo(f, g): """Computes polynomial quotient of ``f`` and ``g``. """ lev, dom, per, F, G = f.unify(g) return per(dmp_quo(F, G, lev, dom)) def exquo(f, g): """Computes polynomial exact quotient of ``f`` and ``g``. """ lev, dom, per, F, G = f.unify(g) res = per(dmp_exquo(F, G, lev, dom)) if f.ring and res not in f.ring: from sympy.polys.polyerrors import ExactQuotientFailed raise ExactQuotientFailed(f, g, f.ring) return res def degree(f, j=0): """Returns the leading degree of ``f`` in ``x_j``. """ if isinstance(j, int): return dmp_degree_in(f.rep, j, f.lev) else: raise TypeError("``int`` expected, got %s" % type(j)) def degree_list(f): """Returns a list of degrees of ``f``. """ return dmp_degree_list(f.rep, f.lev) def total_degree(f): """Returns the total degree of ``f``. """ return max(sum(m) for m in f.monoms()) def homogenize(f, s): """Return homogeneous polynomial of ``f``""" td = f.total_degree() result = {} new_symbol = (s == len(f.terms()[0][0])) for term in f.terms(): d = sum(term[0]) if d < td: i = td - d else: i = 0 if new_symbol: result[term[0] + (i,)] = term[1] else: l = list(term[0]) l[s] += i result[tuple(l)] = term[1] return DMP(result, f.dom, f.lev + int(new_symbol), f.ring) def homogeneous_order(f): """Returns the homogeneous order of ``f``. """ if f.is_zero: return -oo monoms = f.monoms() tdeg = sum(monoms[0]) for monom in monoms: _tdeg = sum(monom) if _tdeg != tdeg: return None return tdeg def LC(f): """Returns the leading coefficient of ``f``. """ return dmp_ground_LC(f.rep, f.lev, f.dom) def TC(f): """Returns the trailing coefficient of ``f``. """ return dmp_ground_TC(f.rep, f.lev, f.dom) def nth(f, *N): """Returns the ``n``-th coefficient of ``f``. """ if all(isinstance(n, int) for n in N): return dmp_ground_nth(f.rep, N, f.lev, f.dom) else: raise TypeError("a sequence of integers expected") def max_norm(f): """Returns maximum norm of ``f``. """ return dmp_max_norm(f.rep, f.lev, f.dom) def l1_norm(f): """Returns l1 norm of ``f``. """ return dmp_l1_norm(f.rep, f.lev, f.dom) def clear_denoms(f): """Clear denominators, but keep the ground domain. """ coeff, F = dmp_clear_denoms(f.rep, f.lev, f.dom) return coeff, f.per(F) def integrate(f, m=1, j=0): """Computes the ``m``-th order indefinite integral of ``f`` in ``x_j``. """ if not isinstance(m, int): raise TypeError("``int`` expected, got %s" % type(m)) if not isinstance(j, int): raise TypeError("``int`` expected, got %s" % type(j)) return f.per(dmp_integrate_in(f.rep, m, j, f.lev, f.dom)) def diff(f, m=1, j=0): """Computes the ``m``-th order derivative of ``f`` in ``x_j``. """ if not isinstance(m, int): raise TypeError("``int`` expected, got %s" % type(m)) if not isinstance(j, int): raise TypeError("``int`` expected, got %s" % type(j)) return f.per(dmp_diff_in(f.rep, m, j, f.lev, f.dom)) def eval(f, a, j=0): """Evaluates ``f`` at the given point ``a`` in ``x_j``. """ if not isinstance(j, int): raise TypeError("``int`` expected, got %s" % type(j)) return f.per(dmp_eval_in(f.rep, f.dom.convert(a), j, f.lev, f.dom), kill=True) def half_gcdex(f, g): """Half extended Euclidean algorithm, if univariate. """ lev, dom, per, F, G = f.unify(g) if not lev: s, h = dup_half_gcdex(F, G, dom) return per(s), per(h) else: raise ValueError('univariate polynomial expected') def gcdex(f, g): """Extended Euclidean algorithm, if univariate. """ lev, dom, per, F, G = f.unify(g) if not lev: s, t, h = dup_gcdex(F, G, dom) return per(s), per(t), per(h) else: raise ValueError('univariate polynomial expected') def invert(f, g): """Invert ``f`` modulo ``g``, if possible. """ lev, dom, per, F, G = f.unify(g) if not lev: return per(dup_invert(F, G, dom)) else: raise ValueError('univariate polynomial expected') def revert(f, n): """Compute ``f**(-1)`` mod ``x**n``. """ if not f.lev: return f.per(dup_revert(f.rep, n, f.dom)) else: raise ValueError('univariate polynomial expected') def subresultants(f, g): """Computes subresultant PRS sequence of ``f`` and ``g``. """ lev, dom, per, F, G = f.unify(g) R = dmp_subresultants(F, G, lev, dom) return list(map(per, R)) def resultant(f, g, includePRS=False): """Computes resultant of ``f`` and ``g`` via PRS. """ lev, dom, per, F, G = f.unify(g) if includePRS: res, R = dmp_resultant(F, G, lev, dom, includePRS=includePRS) return per(res, kill=True), list(map(per, R)) return per(dmp_resultant(F, G, lev, dom), kill=True) def discriminant(f): """Computes discriminant of ``f``. """ return f.per(dmp_discriminant(f.rep, f.lev, f.dom), kill=True) def cofactors(f, g): """Returns GCD of ``f`` and ``g`` and their cofactors. """ lev, dom, per, F, G = f.unify(g) h, cff, cfg = dmp_inner_gcd(F, G, lev, dom) return per(h), per(cff), per(cfg) def gcd(f, g): """Returns polynomial GCD of ``f`` and ``g``. """ lev, dom, per, F, G = f.unify(g) return per(dmp_gcd(F, G, lev, dom)) def lcm(f, g): """Returns polynomial LCM of ``f`` and ``g``. """ lev, dom, per, F, G = f.unify(g) return per(dmp_lcm(F, G, lev, dom)) def cancel(f, g, include=True): """Cancel common factors in a rational function ``f/g``. """ lev, dom, per, F, G = f.unify(g) if include: F, G = dmp_cancel(F, G, lev, dom, include=True) else: cF, cG, F, G = dmp_cancel(F, G, lev, dom, include=False) F, G = per(F), per(G) if include: return F, G else: return cF, cG, F, G def trunc(f, p): """Reduce ``f`` modulo a constant ``p``. """ return f.per(dmp_ground_trunc(f.rep, f.dom.convert(p), f.lev, f.dom)) def monic(f): """Divides all coefficients by ``LC(f)``. """ return f.per(dmp_ground_monic(f.rep, f.lev, f.dom)) def content(f): """Returns GCD of polynomial coefficients. """ return dmp_ground_content(f.rep, f.lev, f.dom) def primitive(f): """Returns content and a primitive form of ``f``. """ cont, F = dmp_ground_primitive(f.rep, f.lev, f.dom) return cont, f.per(F) def compose(f, g): """Computes functional composition of ``f`` and ``g``. """ lev, dom, per, F, G = f.unify(g) return per(dmp_compose(F, G, lev, dom)) def decompose(f): """Computes functional decomposition of ``f``. """ if not f.lev: return list(map(f.per, dup_decompose(f.rep, f.dom))) else: raise ValueError('univariate polynomial expected') def shift(f, a): """Efficiently compute Taylor shift ``f(x + a)``. """ if not f.lev: return f.per(dup_shift(f.rep, f.dom.convert(a), f.dom)) else: raise ValueError('univariate polynomial expected') def transform(f, p, q): """Evaluate functional transformation ``q**n * f(p/q)``.""" if f.lev: raise ValueError('univariate polynomial expected') lev, dom, per, P, Q = p.unify(q) lev, dom, per, F, P = f.unify(per(P, dom, lev)) lev, dom, per, F, Q = per(F, dom, lev).unify(per(Q, dom, lev)) if not lev: return per(dup_transform(F, P, Q, dom)) else: raise ValueError('univariate polynomial expected') def sturm(f): """Computes the Sturm sequence of ``f``. """ if not f.lev: return list(map(f.per, dup_sturm(f.rep, f.dom))) else: raise ValueError('univariate polynomial expected') def gff_list(f): """Computes greatest factorial factorization of ``f``. """ if not f.lev: return [ (f.per(g), k) for g, k in dup_gff_list(f.rep, f.dom) ] else: raise ValueError('univariate polynomial expected') def norm(f): """Computes ``Norm(f)``.""" r = dmp_norm(f.rep, f.lev, f.dom) return f.per(r, dom=f.dom.dom) def sqf_norm(f): """Computes square-free norm of ``f``. """ s, g, r = dmp_sqf_norm(f.rep, f.lev, f.dom) return s, f.per(g), f.per(r, dom=f.dom.dom) def sqf_part(f): """Computes square-free part of ``f``. """ return f.per(dmp_sqf_part(f.rep, f.lev, f.dom)) def sqf_list(f, all=False): """Returns a list of square-free factors of ``f``. """ coeff, factors = dmp_sqf_list(f.rep, f.lev, f.dom, all) return coeff, [ (f.per(g), k) for g, k in factors ] def sqf_list_include(f, all=False): """Returns a list of square-free factors of ``f``. """ factors = dmp_sqf_list_include(f.rep, f.lev, f.dom, all) return [ (f.per(g), k) for g, k in factors ] def factor_list(f): """Returns a list of irreducible factors of ``f``. """ coeff, factors = dmp_factor_list(f.rep, f.lev, f.dom) return coeff, [ (f.per(g), k) for g, k in factors ] def factor_list_include(f): """Returns a list of irreducible factors of ``f``. """ factors = dmp_factor_list_include(f.rep, f.lev, f.dom) return [ (f.per(g), k) for g, k in factors ] def intervals(f, all=False, eps=None, inf=None, sup=None, fast=False, sqf=False): """Compute isolating intervals for roots of ``f``. """ if not f.lev: if not all: if not sqf: return dup_isolate_real_roots(f.rep, f.dom, eps=eps, inf=inf, sup=sup, fast=fast) else: return dup_isolate_real_roots_sqf(f.rep, f.dom, eps=eps, inf=inf, sup=sup, fast=fast) else: if not sqf: return dup_isolate_all_roots(f.rep, f.dom, eps=eps, inf=inf, sup=sup, fast=fast) else: return dup_isolate_all_roots_sqf(f.rep, f.dom, eps=eps, inf=inf, sup=sup, fast=fast) else: raise PolynomialError( "can't isolate roots of a multivariate polynomial") def refine_root(f, s, t, eps=None, steps=None, fast=False): """ Refine an isolating interval to the given precision. ``eps`` should be a rational number. """ if not f.lev: return dup_refine_real_root(f.rep, s, t, f.dom, eps=eps, steps=steps, fast=fast) else: raise PolynomialError( "can't refine a root of a multivariate polynomial") def count_real_roots(f, inf=None, sup=None): """Return the number of real roots of ``f`` in ``[inf, sup]``. """ return dup_count_real_roots(f.rep, f.dom, inf=inf, sup=sup) def count_complex_roots(f, inf=None, sup=None): """Return the number of complex roots of ``f`` in ``[inf, sup]``. """ return dup_count_complex_roots(f.rep, f.dom, inf=inf, sup=sup) @property def is_zero(f): """Returns ``True`` if ``f`` is a zero polynomial. """ return dmp_zero_p(f.rep, f.lev) @property def is_one(f): """Returns ``True`` if ``f`` is a unit polynomial. """ return dmp_one_p(f.rep, f.lev, f.dom) @property def is_ground(f): """Returns ``True`` if ``f`` is an element of the ground domain. """ return dmp_ground_p(f.rep, None, f.lev) @property def is_sqf(f): """Returns ``True`` if ``f`` is a square-free polynomial. """ return dmp_sqf_p(f.rep, f.lev, f.dom) @property def is_monic(f): """Returns ``True`` if the leading coefficient of ``f`` is one. """ return f.dom.is_one(dmp_ground_LC(f.rep, f.lev, f.dom)) @property def is_primitive(f): """Returns ``True`` if the GCD of the coefficients of ``f`` is one. """ return f.dom.is_one(dmp_ground_content(f.rep, f.lev, f.dom)) @property def is_linear(f): """Returns ``True`` if ``f`` is linear in all its variables. """ return all(sum(monom) <= 1 for monom in dmp_to_dict(f.rep, f.lev, f.dom).keys()) @property def is_quadratic(f): """Returns ``True`` if ``f`` is quadratic in all its variables. """ return all(sum(monom) <= 2 for monom in dmp_to_dict(f.rep, f.lev, f.dom).keys()) @property def is_monomial(f): """Returns ``True`` if ``f`` is zero or has only one term. """ return len(f.to_dict()) <= 1 @property def is_homogeneous(f): """Returns ``True`` if ``f`` is a homogeneous polynomial. """ return f.homogeneous_order() is not None @property def is_irreducible(f): """Returns ``True`` if ``f`` has no factors over its domain. """ return dmp_irreducible_p(f.rep, f.lev, f.dom) @property def is_cyclotomic(f): """Returns ``True`` if ``f`` is a cyclotomic polynomial. """ if not f.lev: return dup_cyclotomic_p(f.rep, f.dom) else: return False def __abs__(f): return f.abs() def __neg__(f): return f.neg() def __add__(f, g): if not isinstance(g, DMP): try: g = f.per(dmp_ground(f.dom.convert(g), f.lev)) except TypeError: return NotImplemented except (CoercionFailed, NotImplementedError): if f.ring is not None: try: g = f.ring.convert(g) except (CoercionFailed, NotImplementedError): return NotImplemented return f.add(g) def __radd__(f, g): return f.__add__(g) def __sub__(f, g): if not isinstance(g, DMP): try: g = f.per(dmp_ground(f.dom.convert(g), f.lev)) except TypeError: return NotImplemented except (CoercionFailed, NotImplementedError): if f.ring is not None: try: g = f.ring.convert(g) except (CoercionFailed, NotImplementedError): return NotImplemented return f.sub(g) def __rsub__(f, g): return (-f).__add__(g) def __mul__(f, g): if isinstance(g, DMP): return f.mul(g) else: try: return f.mul_ground(g) except TypeError: return NotImplemented except (CoercionFailed, NotImplementedError): if f.ring is not None: try: return f.mul(f.ring.convert(g)) except (CoercionFailed, NotImplementedError): pass return NotImplemented def __div__(f, g): if isinstance(g, DMP): return f.exquo(g) else: try: return f.mul_ground(g) except TypeError: return NotImplemented except (CoercionFailed, NotImplementedError): if f.ring is not None: try: return f.exquo(f.ring.convert(g)) except (CoercionFailed, NotImplementedError): pass return NotImplemented def __rdiv__(f, g): if isinstance(g, DMP): return g.exquo(f) elif f.ring is not None: try: return f.ring.convert(g).exquo(f) except (CoercionFailed, NotImplementedError): pass return NotImplemented __truediv__ = __div__ __rtruediv__ = __rdiv__ def __rmul__(f, g): return f.__mul__(g) def __pow__(f, n): return f.pow(n) def __divmod__(f, g): return f.div(g) def __mod__(f, g): return f.rem(g) def __floordiv__(f, g): if isinstance(g, DMP): return f.quo(g) else: try: return f.quo_ground(g) except TypeError: return NotImplemented def __eq__(f, g): try: _, _, _, F, G = f.unify(g) if f.lev == g.lev: return F == G except UnificationFailed: pass return False def __ne__(f, g): return not f == g def eq(f, g, strict=False): if not strict: return f == g else: return f._strict_eq(g) def ne(f, g, strict=False): return not f.eq(g, strict=strict) def _strict_eq(f, g): return isinstance(g, f.__class__) and f.lev == g.lev \ and f.dom == g.dom \ and f.rep == g.rep def __lt__(f, g): _, _, _, F, G = f.unify(g) return F < G def __le__(f, g): _, _, _, F, G = f.unify(g) return F <= G def __gt__(f, g): _, _, _, F, G = f.unify(g) return F > G def __ge__(f, g): _, _, _, F, G = f.unify(g) return F >= G def __nonzero__(f): return not dmp_zero_p(f.rep, f.lev) __bool__ = __nonzero__ def init_normal_DMF(num, den, lev, dom): return DMF(dmp_normal(num, lev, dom), dmp_normal(den, lev, dom), dom, lev) class DMF(PicklableWithSlots, CantSympify): """Dense Multivariate Fractions over `K`. """ __slots__ = ['num', 'den', 'lev', 'dom', 'ring'] def __init__(self, rep, dom, lev=None, ring=None): num, den, lev = self._parse(rep, dom, lev) num, den = dmp_cancel(num, den, lev, dom) self.num = num self.den = den self.lev = lev self.dom = dom self.ring = ring @classmethod def new(cls, rep, dom, lev=None, ring=None): num, den, lev = cls._parse(rep, dom, lev) obj = object.__new__(cls) obj.num = num obj.den = den obj.lev = lev obj.dom = dom obj.ring = ring return obj @classmethod def _parse(cls, rep, dom, lev=None): if type(rep) is tuple: num, den = rep if lev is not None: if type(num) is dict: num = dmp_from_dict(num, lev, dom) if type(den) is dict: den = dmp_from_dict(den, lev, dom) else: num, num_lev = dmp_validate(num) den, den_lev = dmp_validate(den) if num_lev == den_lev: lev = num_lev else: raise ValueError('inconsistent number of levels') if dmp_zero_p(den, lev): raise ZeroDivisionError('fraction denominator') if dmp_zero_p(num, lev): den = dmp_one(lev, dom) else: if dmp_negative_p(den, lev, dom): num = dmp_neg(num, lev, dom) den = dmp_neg(den, lev, dom) else: num = rep if lev is not None: if type(num) is dict: num = dmp_from_dict(num, lev, dom) elif type(num) is not list: num = dmp_ground(dom.convert(num), lev) else: num, lev = dmp_validate(num) den = dmp_one(lev, dom) return num, den, lev def __repr__(f): return "%s((%s, %s), %s, %s)" % (f.__class__.__name__, f.num, f.den, f.dom, f.ring) def __hash__(f): return hash((f.__class__.__name__, dmp_to_tuple(f.num, f.lev), dmp_to_tuple(f.den, f.lev), f.lev, f.dom, f.ring)) def poly_unify(f, g): """Unify a multivariate fraction and a polynomial. """ if not isinstance(g, DMP) or f.lev != g.lev: raise UnificationFailed("can't unify %s with %s" % (f, g)) if f.dom == g.dom and f.ring == g.ring: return (f.lev, f.dom, f.per, (f.num, f.den), g.rep) else: lev, dom = f.lev, f.dom.unify(g.dom) ring = f.ring if g.ring is not None: if ring is not None: ring = ring.unify(g.ring) else: ring = g.ring F = (dmp_convert(f.num, lev, f.dom, dom), dmp_convert(f.den, lev, f.dom, dom)) G = dmp_convert(g.rep, lev, g.dom, dom) def per(num, den, cancel=True, kill=False, lev=lev): if kill: if not lev: return num/den else: lev = lev - 1 if cancel: num, den = dmp_cancel(num, den, lev, dom) return f.__class__.new((num, den), dom, lev, ring=ring) return lev, dom, per, F, G def frac_unify(f, g): """Unify representations of two multivariate fractions. """ if not isinstance(g, DMF) or f.lev != g.lev: raise UnificationFailed("can't unify %s with %s" % (f, g)) if f.dom == g.dom and f.ring == g.ring: return (f.lev, f.dom, f.per, (f.num, f.den), (g.num, g.den)) else: lev, dom = f.lev, f.dom.unify(g.dom) ring = f.ring if g.ring is not None: if ring is not None: ring = ring.unify(g.ring) else: ring = g.ring F = (dmp_convert(f.num, lev, f.dom, dom), dmp_convert(f.den, lev, f.dom, dom)) G = (dmp_convert(g.num, lev, g.dom, dom), dmp_convert(g.den, lev, g.dom, dom)) def per(num, den, cancel=True, kill=False, lev=lev): if kill: if not lev: return num/den else: lev = lev - 1 if cancel: num, den = dmp_cancel(num, den, lev, dom) return f.__class__.new((num, den), dom, lev, ring=ring) return lev, dom, per, F, G def per(f, num, den, cancel=True, kill=False, ring=None): """Create a DMF out of the given representation. """ lev, dom = f.lev, f.dom if kill: if not lev: return num/den else: lev -= 1 if cancel: num, den = dmp_cancel(num, den, lev, dom) if ring is None: ring = f.ring return f.__class__.new((num, den), dom, lev, ring=ring) def half_per(f, rep, kill=False): """Create a DMP out of the given representation. """ lev = f.lev if kill: if not lev: return rep else: lev -= 1 return DMP(rep, f.dom, lev) @classmethod def zero(cls, lev, dom, ring=None): return cls.new(0, dom, lev, ring=ring) @classmethod def one(cls, lev, dom, ring=None): return cls.new(1, dom, lev, ring=ring) def numer(f): """Returns the numerator of ``f``. """ return f.half_per(f.num) def denom(f): """Returns the denominator of ``f``. """ return f.half_per(f.den) def cancel(f): """Remove common factors from ``f.num`` and ``f.den``. """ return f.per(f.num, f.den) def neg(f): """Negate all coefficients in ``f``. """ return f.per(dmp_neg(f.num, f.lev, f.dom), f.den, cancel=False) def add(f, g): """Add two multivariate fractions ``f`` and ``g``. """ if isinstance(g, DMP): lev, dom, per, (F_num, F_den), G = f.poly_unify(g) num, den = dmp_add_mul(F_num, F_den, G, lev, dom), F_den else: lev, dom, per, F, G = f.frac_unify(g) (F_num, F_den), (G_num, G_den) = F, G num = dmp_add(dmp_mul(F_num, G_den, lev, dom), dmp_mul(F_den, G_num, lev, dom), lev, dom) den = dmp_mul(F_den, G_den, lev, dom) return per(num, den) def sub(f, g): """Subtract two multivariate fractions ``f`` and ``g``. """ if isinstance(g, DMP): lev, dom, per, (F_num, F_den), G = f.poly_unify(g) num, den = dmp_sub_mul(F_num, F_den, G, lev, dom), F_den else: lev, dom, per, F, G = f.frac_unify(g) (F_num, F_den), (G_num, G_den) = F, G num = dmp_sub(dmp_mul(F_num, G_den, lev, dom), dmp_mul(F_den, G_num, lev, dom), lev, dom) den = dmp_mul(F_den, G_den, lev, dom) return per(num, den) def mul(f, g): """Multiply two multivariate fractions ``f`` and ``g``. """ if isinstance(g, DMP): lev, dom, per, (F_num, F_den), G = f.poly_unify(g) num, den = dmp_mul(F_num, G, lev, dom), F_den else: lev, dom, per, F, G = f.frac_unify(g) (F_num, F_den), (G_num, G_den) = F, G num = dmp_mul(F_num, G_num, lev, dom) den = dmp_mul(F_den, G_den, lev, dom) return per(num, den) def pow(f, n): """Raise ``f`` to a non-negative power ``n``. """ if isinstance(n, int): return f.per(dmp_pow(f.num, n, f.lev, f.dom), dmp_pow(f.den, n, f.lev, f.dom), cancel=False) else: raise TypeError("``int`` expected, got %s" % type(n)) def quo(f, g): """Computes quotient of fractions ``f`` and ``g``. """ if isinstance(g, DMP): lev, dom, per, (F_num, F_den), G = f.poly_unify(g) num, den = F_num, dmp_mul(F_den, G, lev, dom) else: lev, dom, per, F, G = f.frac_unify(g) (F_num, F_den), (G_num, G_den) = F, G num = dmp_mul(F_num, G_den, lev, dom) den = dmp_mul(F_den, G_num, lev, dom) res = per(num, den) if f.ring is not None and res not in f.ring: from sympy.polys.polyerrors import ExactQuotientFailed raise ExactQuotientFailed(f, g, f.ring) return res exquo = quo def invert(f, check=True): """Computes inverse of a fraction ``f``. """ if check and f.ring is not None and not f.ring.is_unit(f): raise NotReversible(f, f.ring) res = f.per(f.den, f.num, cancel=False) return res @property def is_zero(f): """Returns ``True`` if ``f`` is a zero fraction. """ return dmp_zero_p(f.num, f.lev) @property def is_one(f): """Returns ``True`` if ``f`` is a unit fraction. """ return dmp_one_p(f.num, f.lev, f.dom) and \ dmp_one_p(f.den, f.lev, f.dom) def __neg__(f): return f.neg() def __add__(f, g): if isinstance(g, (DMP, DMF)): return f.add(g) try: return f.add(f.half_per(g)) except TypeError: return NotImplemented except (CoercionFailed, NotImplementedError): if f.ring is not None: try: return f.add(f.ring.convert(g)) except (CoercionFailed, NotImplementedError): pass return NotImplemented def __radd__(f, g): return f.__add__(g) def __sub__(f, g): if isinstance(g, (DMP, DMF)): return f.sub(g) try: return f.sub(f.half_per(g)) except TypeError: return NotImplemented except (CoercionFailed, NotImplementedError): if f.ring is not None: try: return f.sub(f.ring.convert(g)) except (CoercionFailed, NotImplementedError): pass return NotImplemented def __rsub__(f, g): return (-f).__add__(g) def __mul__(f, g): if isinstance(g, (DMP, DMF)): return f.mul(g) try: return f.mul(f.half_per(g)) except TypeError: return NotImplemented except (CoercionFailed, NotImplementedError): if f.ring is not None: try: return f.mul(f.ring.convert(g)) except (CoercionFailed, NotImplementedError): pass return NotImplemented def __rmul__(f, g): return f.__mul__(g) def __pow__(f, n): return f.pow(n) def __div__(f, g): if isinstance(g, (DMP, DMF)): return f.quo(g) try: return f.quo(f.half_per(g)) except TypeError: return NotImplemented except (CoercionFailed, NotImplementedError): if f.ring is not None: try: return f.quo(f.ring.convert(g)) except (CoercionFailed, NotImplementedError): pass return NotImplemented def __rdiv__(self, g): r = self.invert(check=False)*g if self.ring and r not in self.ring: from sympy.polys.polyerrors import ExactQuotientFailed raise ExactQuotientFailed(g, self, self.ring) return r __truediv__ = __div__ __rtruediv__ = __rdiv__ def __eq__(f, g): try: if isinstance(g, DMP): _, _, _, (F_num, F_den), G = f.poly_unify(g) if f.lev == g.lev: return dmp_one_p(F_den, f.lev, f.dom) and F_num == G else: _, _, _, F, G = f.frac_unify(g) if f.lev == g.lev: return F == G except UnificationFailed: pass return False def __ne__(f, g): try: if isinstance(g, DMP): _, _, _, (F_num, F_den), G = f.poly_unify(g) if f.lev == g.lev: return not (dmp_one_p(F_den, f.lev, f.dom) and F_num == G) else: _, _, _, F, G = f.frac_unify(g) if f.lev == g.lev: return F != G except UnificationFailed: pass return True def __lt__(f, g): _, _, _, F, G = f.frac_unify(g) return F < G def __le__(f, g): _, _, _, F, G = f.frac_unify(g) return F <= G def __gt__(f, g): _, _, _, F, G = f.frac_unify(g) return F > G def __ge__(f, g): _, _, _, F, G = f.frac_unify(g) return F >= G def __nonzero__(f): return not dmp_zero_p(f.num, f.lev) __bool__ = __nonzero__ def init_normal_ANP(rep, mod, dom): return ANP(dup_normal(rep, dom), dup_normal(mod, dom), dom) class ANP(PicklableWithSlots, CantSympify): """Dense Algebraic Number Polynomials over a field. """ __slots__ = ['rep', 'mod', 'dom'] def __init__(self, rep, mod, dom): if type(rep) is dict: self.rep = dup_from_dict(rep, dom) else: if type(rep) is not list: rep = [dom.convert(rep)] self.rep = dup_strip(rep) if isinstance(mod, DMP): self.mod = mod.rep else: if type(mod) is dict: self.mod = dup_from_dict(mod, dom) else: self.mod = dup_strip(mod) self.dom = dom def __repr__(f): return "%s(%s, %s, %s)" % (f.__class__.__name__, f.rep, f.mod, f.dom) def __hash__(f): return hash((f.__class__.__name__, f.to_tuple(), dmp_to_tuple(f.mod, 0), f.dom)) def unify(f, g): """Unify representations of two algebraic numbers. """ if not isinstance(g, ANP) or f.mod != g.mod: raise UnificationFailed("can't unify %s with %s" % (f, g)) if f.dom == g.dom: return f.dom, f.per, f.rep, g.rep, f.mod else: dom = f.dom.unify(g.dom) F = dup_convert(f.rep, f.dom, dom) G = dup_convert(g.rep, g.dom, dom) if dom != f.dom and dom != g.dom: mod = dup_convert(f.mod, f.dom, dom) else: if dom == f.dom: mod = f.mod else: mod = g.mod per = lambda rep: ANP(rep, mod, dom) return dom, per, F, G, mod def per(f, rep, mod=None, dom=None): return ANP(rep, mod or f.mod, dom or f.dom) @classmethod def zero(cls, mod, dom): return ANP(0, mod, dom) @classmethod def one(cls, mod, dom): return ANP(1, mod, dom) def to_dict(f): """Convert ``f`` to a dict representation with native coefficients. """ return dmp_to_dict(f.rep, 0, f.dom) def to_sympy_dict(f): """Convert ``f`` to a dict representation with SymPy coefficients. """ rep = dmp_to_dict(f.rep, 0, f.dom) for k, v in rep.items(): rep[k] = f.dom.to_sympy(v) return rep def to_list(f): """Convert ``f`` to a list representation with native coefficients. """ return f.rep def to_sympy_list(f): """Convert ``f`` to a list representation with SymPy coefficients. """ return [ f.dom.to_sympy(c) for c in f.rep ] def to_tuple(f): """ Convert ``f`` to a tuple representation with native coefficients. This is needed for hashing. """ return dmp_to_tuple(f.rep, 0) @classmethod def from_list(cls, rep, mod, dom): return ANP(dup_strip(list(map(dom.convert, rep))), mod, dom) def neg(f): return f.per(dup_neg(f.rep, f.dom)) def add(f, g): dom, per, F, G, mod = f.unify(g) return per(dup_add(F, G, dom)) def sub(f, g): dom, per, F, G, mod = f.unify(g) return per(dup_sub(F, G, dom)) def mul(f, g): dom, per, F, G, mod = f.unify(g) return per(dup_rem(dup_mul(F, G, dom), mod, dom)) def pow(f, n): """Raise ``f`` to a non-negative power ``n``. """ if isinstance(n, int): if n < 0: F, n = dup_invert(f.rep, f.mod, f.dom), -n else: F = f.rep return f.per(dup_rem(dup_pow(F, n, f.dom), f.mod, f.dom)) else: raise TypeError("``int`` expected, got %s" % type(n)) def div(f, g): dom, per, F, G, mod = f.unify(g) return (per(dup_rem(dup_mul(F, dup_invert(G, mod, dom), dom), mod, dom)), f.zero(mod, dom)) def rem(f, g): dom, _, _, G, mod = f.unify(g) s, h = dup_half_gcdex(G, mod, dom) if h == [dom.one]: return f.zero(mod, dom) else: raise NotInvertible("zero divisor") def quo(f, g): dom, per, F, G, mod = f.unify(g) return per(dup_rem(dup_mul(F, dup_invert(G, mod, dom), dom), mod, dom)) exquo = quo def LC(f): """Returns the leading coefficient of ``f``. """ return dup_LC(f.rep, f.dom) def TC(f): """Returns the trailing coefficient of ``f``. """ return dup_TC(f.rep, f.dom) @property def is_zero(f): """Returns ``True`` if ``f`` is a zero algebraic number. """ return not f @property def is_one(f): """Returns ``True`` if ``f`` is a unit algebraic number. """ return f.rep == [f.dom.one] @property def is_ground(f): """Returns ``True`` if ``f`` is an element of the ground domain. """ return not f.rep or len(f.rep) == 1 def __neg__(f): return f.neg() def __add__(f, g): if isinstance(g, ANP): return f.add(g) else: try: return f.add(f.per(g)) except (CoercionFailed, TypeError): return NotImplemented def __radd__(f, g): return f.__add__(g) def __sub__(f, g): if isinstance(g, ANP): return f.sub(g) else: try: return f.sub(f.per(g)) except (CoercionFailed, TypeError): return NotImplemented def __rsub__(f, g): return (-f).__add__(g) def __mul__(f, g): if isinstance(g, ANP): return f.mul(g) else: try: return f.mul(f.per(g)) except (CoercionFailed, TypeError): return NotImplemented def __rmul__(f, g): return f.__mul__(g) def __pow__(f, n): return f.pow(n) def __divmod__(f, g): return f.div(g) def __mod__(f, g): return f.rem(g) def __div__(f, g): if isinstance(g, ANP): return f.quo(g) else: try: return f.quo(f.per(g)) except (CoercionFailed, TypeError): return NotImplemented __truediv__ = __div__ def __eq__(f, g): try: _, _, F, G, _ = f.unify(g) return F == G except UnificationFailed: return False def __ne__(f, g): try: _, _, F, G, _ = f.unify(g) return F != G except UnificationFailed: return True def __lt__(f, g): _, _, F, G, _ = f.unify(g) return F < G def __le__(f, g): _, _, F, G, _ = f.unify(g) return F <= G def __gt__(f, g): _, _, F, G, _ = f.unify(g) return F > G def __ge__(f, g): _, _, F, G, _ = f.unify(g) return F >= G def __nonzero__(f): return bool(f.rep) __bool__ = __nonzero__

6669c5fe53c8bf26f61a102b93dc8a0c96033933c5bdd53b4d46196fe0a2e28a

""" Solving solvable quintics - An implementation of DS Dummit's paper Paper : http://www.ams.org/journals/mcom/1991-57-195/S0025-5718-1991-1079014-X/S0025-5718-1991-1079014-X.pdf Mathematica notebook: http://www.emba.uvm.edu/~ddummit/quintics/quintics.nb """ from __future__ import print_function, division from sympy.core import S, Symbol from sympy.core.evalf import N from sympy.core.numbers import I from sympy.functions import sqrt from sympy.polys.polytools import Poly from sympy.utilities import public x = Symbol('x') @public class PolyQuintic(object): """Special functions for solvable quintics""" def __init__(self, poly): _, _, self.p, self.q, self.r, self.s = poly.all_coeffs() self.zeta1 = S(-1)/4 + (sqrt(5)/4) + I*sqrt((sqrt(5)/8) + S(5)/8) self.zeta2 = (-sqrt(5)/4) - S(1)/4 + I*sqrt((-sqrt(5)/8) + S(5)/8) self.zeta3 = (-sqrt(5)/4) - S(1)/4 - I*sqrt((-sqrt(5)/8) + S(5)/8) self.zeta4 = S(-1)/4 + (sqrt(5)/4) - I*sqrt((sqrt(5)/8) + S(5)/8) @property def f20(self): p, q, r, s = self.p, self.q, self.r, self.s f20 = q**8 - 13*p*q**6*r + p**5*q**2*r**2 + 65*p**2*q**4*r**2 - 4*p**6*r**3 - 128*p**3*q**2*r**3 + 17*q**4*r**3 + 48*p**4*r**4 - 16*p*q**2*r**4 - 192*p**2*r**5 + 256*r**6 - 4*p**5*q**3*s - 12*p**2*q**5*s + 18*p**6*q*r*s + 12*p**3*q**3*r*s - 124*q**5*r*s + 196*p**4*q*r**2*s + 590*p*q**3*r**2*s - 160*p**2*q*r**3*s - 1600*q*r**4*s - 27*p**7*s**2 - 150*p**4*q**2*s**2 - 125*p*q**4*s**2 - 99*p**5*r*s**2 - 725*p**2*q**2*r*s**2 + 1200*p**3*r**2*s**2 + 3250*q**2*r**2*s**2 - 2000*p*r**3*s**2 - 1250*p*q*r*s**3 + 3125*p**2*s**4 - 9375*r*s**4-(2*p*q**6 - 19*p**2*q**4*r + 51*p**3*q**2*r**2 - 3*q**4*r**2 - 32*p**4*r**3 - 76*p*q**2*r**3 + 256*p**2*r**4 - 512*r**5 + 31*p**3*q**3*s + 58*q**5*s - 117*p**4*q*r*s - 105*p*q**3*r*s - 260*p**2*q*r**2*s + 2400*q*r**3*s + 108*p**5*s**2 + 325*p**2*q**2*s**2 - 525*p**3*r*s**2 - 2750*q**2*r*s**2 + 500*p*r**2*s**2 - 625*p*q*s**3 + 3125*s**4)*x+(p**2*q**4 - 6*p**3*q**2*r - 8*q**4*r + 9*p**4*r**2 + 76*p*q**2*r**2 - 136*p**2*r**3 + 400*r**4 - 50*p*q**3*s + 90*p**2*q*r*s - 1400*q*r**2*s + 625*q**2*s**2 + 500*p*r*s**2)*x**2-(2*q**4 - 21*p*q**2*r + 40*p**2*r**2 - 160*r**3 + 15*p**2*q*s + 400*q*r*s - 125*p*s**2)*x**3+(2*p*q**2 - 6*p**2*r + 40*r**2 - 50*q*s)*x**4 + 8*r*x**5 + x**6 return Poly(f20, x) @property def b(self): p, q, r, s = self.p, self.q, self.r, self.s b = ( [], [0,0,0,0,0,0], [0,0,0,0,0,0], [0,0,0,0,0,0], [0,0,0,0,0,0],) b[1][5] = 100*p**7*q**7 + 2175*p**4*q**9 + 10500*p*q**11 - 1100*p**8*q**5*r - 27975*p**5*q**7*r - 152950*p**2*q**9*r + 4125*p**9*q**3*r**2 + 128875*p**6*q**5*r**2 + 830525*p**3*q**7*r**2 - 59450*q**9*r**2 - 5400*p**10*q*r**3 - 243800*p**7*q**3*r**3 - 2082650*p**4*q**5*r**3 + 333925*p*q**7*r**3 + 139200*p**8*q*r**4 + 2406000*p**5*q**3*r**4 + 122600*p**2*q**5*r**4 - 1254400*p**6*q*r**5 - 3776000*p**3*q**3*r**5 - 1832000*q**5*r**5 + 4736000*p**4*q*r**6 + 6720000*p*q**3*r**6 - 6400000*p**2*q*r**7 + 900*p**9*q**4*s + 37400*p**6*q**6*s + 281625*p**3*q**8*s + 435000*q**10*s - 6750*p**10*q**2*r*s - 322300*p**7*q**4*r*s - 2718575*p**4*q**6*r*s - 4214250*p*q**8*r*s + 16200*p**11*r**2*s + 859275*p**8*q**2*r**2*s + 8925475*p**5*q**4*r**2*s + 14427875*p**2*q**6*r**2*s - 453600*p**9*r**3*s - 10038400*p**6*q**2*r**3*s - 17397500*p**3*q**4*r**3*s + 11333125*q**6*r**3*s + 4451200*p**7*r**4*s + 15850000*p**4*q**2*r**4*s - 34000000*p*q**4*r**4*s - 17984000*p**5*r**5*s + 10000000*p**2*q**2*r**5*s + 25600000*p**3*r**6*s + 8000000*q**2*r**6*s - 6075*p**11*q*s**2 + 83250*p**8*q**3*s**2 + 1282500*p**5*q**5*s**2 + 2862500*p**2*q**7*s**2 - 724275*p**9*q*r*s**2 - 9807250*p**6*q**3*r*s**2 - 28374375*p**3*q**5*r*s**2 - 22212500*q**7*r*s**2 + 8982000*p**7*q*r**2*s**2 + 39600000*p**4*q**3*r**2*s**2 + 61746875*p*q**5*r**2*s**2 + 1010000*p**5*q*r**3*s**2 + 1000000*p**2*q**3*r**3*s**2 - 78000000*p**3*q*r**4*s**2 - 30000000*q**3*r**4*s**2 - 80000000*p*q*r**5*s**2 + 759375*p**10*s**3 + 9787500*p**7*q**2*s**3 + 39062500*p**4*q**4*s**3 + 52343750*p*q**6*s**3 - 12301875*p**8*r*s**3 - 98175000*p**5*q**2*r*s**3 - 225078125*p**2*q**4*r*s**3 + 54900000*p**6*r**2*s**3 + 310000000*p**3*q**2*r**2*s**3 + 7890625*q**4*r**2*s**3 - 51250000*p**4*r**3*s**3 + 420000000*p*q**2*r**3*s**3 - 110000000*p**2*r**4*s**3 + 200000000*r**5*s**3 - 2109375*p**6*q*s**4 + 21093750*p**3*q**3*s**4 + 89843750*q**5*s**4 - 182343750*p**4*q*r*s**4 - 733203125*p*q**3*r*s**4 + 196875000*p**2*q*r**2*s**4 - 1125000000*q*r**3*s**4 + 158203125*p**5*s**5 + 566406250*p**2*q**2*s**5 - 101562500*p**3*r*s**5 + 1669921875*q**2*r*s**5 - 1250000000*p*r**2*s**5 + 1220703125*p*q*s**6 - 6103515625*s**7 b[1][4] = -1000*p**5*q**7 - 7250*p**2*q**9 + 10800*p**6*q**5*r + 96900*p**3*q**7*r + 52500*q**9*r - 37400*p**7*q**3*r**2 - 470850*p**4*q**5*r**2 - 640600*p*q**7*r**2 + 39600*p**8*q*r**3 + 983600*p**5*q**3*r**3 + 2848100*p**2*q**5*r**3 - 814400*p**6*q*r**4 - 6076000*p**3*q**3*r**4 - 2308000*q**5*r**4 + 5024000*p**4*q*r**5 + 9680000*p*q**3*r**5 - 9600000*p**2*q*r**6 - 13800*p**7*q**4*s - 94650*p**4*q**6*s + 26500*p*q**8*s + 86400*p**8*q**2*r*s + 816500*p**5*q**4*r*s + 257500*p**2*q**6*r*s - 91800*p**9*r**2*s - 1853700*p**6*q**2*r**2*s - 630000*p**3*q**4*r**2*s + 8971250*q**6*r**2*s + 2071200*p**7*r**3*s + 7240000*p**4*q**2*r**3*s - 29375000*p*q**4*r**3*s - 14416000*p**5*r**4*s + 5200000*p**2*q**2*r**4*s + 30400000*p**3*r**5*s + 12000000*q**2*r**5*s - 64800*p**9*q*s**2 - 567000*p**6*q**3*s**2 - 1655000*p**3*q**5*s**2 - 6987500*q**7*s**2 - 337500*p**7*q*r*s**2 - 8462500*p**4*q**3*r*s**2 + 5812500*p*q**5*r*s**2 + 24930000*p**5*q*r**2*s**2 + 69125000*p**2*q**3*r**2*s**2 - 103500000*p**3*q*r**3*s**2 - 30000000*q**3*r**3*s**2 - 90000000*p*q*r**4*s**2 + 708750*p**8*s**3 + 5400000*p**5*q**2*s**3 - 8906250*p**2*q**4*s**3 - 18562500*p**6*r*s**3 + 625000*p**3*q**2*r*s**3 - 29687500*q**4*r*s**3 + 75000000*p**4*r**2*s**3 + 416250000*p*q**2*r**2*s**3 - 60000000*p**2*r**3*s**3 + 300000000*r**4*s**3 - 71718750*p**4*q*s**4 - 189062500*p*q**3*s**4 - 210937500*p**2*q*r*s**4 - 1187500000*q*r**2*s**4 + 187500000*p**3*s**5 + 800781250*q**2*s**5 + 390625000*p*r*s**5 b[1][3] = 500*p**6*q**5 + 6350*p**3*q**7 + 19800*q**9 - 3750*p**7*q**3*r - 65100*p**4*q**5*r - 264950*p*q**7*r + 6750*p**8*q*r**2 + 209050*p**5*q**3*r**2 + 1217250*p**2*q**5*r**2 - 219000*p**6*q*r**3 - 2510000*p**3*q**3*r**3 - 1098500*q**5*r**3 + 2068000*p**4*q*r**4 + 5060000*p*q**3*r**4 - 5200000*p**2*q*r**5 + 6750*p**8*q**2*s + 96350*p**5*q**4*s + 346000*p**2*q**6*s - 20250*p**9*r*s - 459900*p**6*q**2*r*s - 1828750*p**3*q**4*r*s + 2930000*q**6*r*s + 594000*p**7*r**2*s + 4301250*p**4*q**2*r**2*s - 10906250*p*q**4*r**2*s - 5252000*p**5*r**3*s + 1450000*p**2*q**2*r**3*s + 12800000*p**3*r**4*s + 6500000*q**2*r**4*s - 74250*p**7*q*s**2 - 1418750*p**4*q**3*s**2 - 5956250*p*q**5*s**2 + 4297500*p**5*q*r*s**2 + 29906250*p**2*q**3*r*s**2 - 31500000*p**3*q*r**2*s**2 - 12500000*q**3*r**2*s**2 - 35000000*p*q*r**3*s**2 - 1350000*p**6*s**3 - 6093750*p**3*q**2*s**3 - 17500000*q**4*s**3 + 7031250*p**4*r*s**3 + 127812500*p*q**2*r*s**3 - 18750000*p**2*r**2*s**3 + 162500000*r**3*s**3 - 107812500*p**2*q*s**4 - 460937500*q*r*s**4 + 214843750*p*s**5 b[1][2] = -1950*p**4*q**5 - 14100*p*q**7 + 14350*p**5*q**3*r + 125600*p**2*q**5*r - 27900*p**6*q*r**2 - 402250*p**3*q**3*r**2 - 288250*q**5*r**2 + 436000*p**4*q*r**3 + 1345000*p*q**3*r**3 - 1400000*p**2*q*r**4 - 9450*p**6*q**2*s + 1250*p**3*q**4*s + 465000*q**6*s + 49950*p**7*r*s + 302500*p**4*q**2*r*s - 1718750*p*q**4*r*s - 834000*p**5*r**2*s - 437500*p**2*q**2*r**2*s + 3100000*p**3*r**3*s + 1750000*q**2*r**3*s + 292500*p**5*q*s**2 + 1937500*p**2*q**3*s**2 - 3343750*p**3*q*r*s**2 - 1875000*q**3*r*s**2 - 8125000*p*q*r**2*s**2 + 1406250*p**4*s**3 + 12343750*p*q**2*s**3 - 5312500*p**2*r*s**3 + 43750000*r**2*s**3 - 74218750*q*s**4 b[1][1] = 300*p**5*q**3 + 2150*p**2*q**5 - 1350*p**6*q*r - 21500*p**3*q**3*r - 61500*q**5*r + 42000*p**4*q*r**2 + 290000*p*q**3*r**2 - 300000*p**2*q*r**3 + 4050*p**7*s + 45000*p**4*q**2*s + 125000*p*q**4*s - 108000*p**5*r*s - 643750*p**2*q**2*r*s + 700000*p**3*r**2*s + 375000*q**2*r**2*s + 93750*p**3*q*s**2 + 312500*q**3*s**2 - 1875000*p*q*r*s**2 + 1406250*p**2*s**3 + 9375000*r*s**3 b[1][0] = -1250*p**3*q**3 - 9000*q**5 + 4500*p**4*q*r + 46250*p*q**3*r - 50000*p**2*q*r**2 - 6750*p**5*s - 43750*p**2*q**2*s + 75000*p**3*r*s + 62500*q**2*r*s - 156250*p*q*s**2 + 1562500*s**3 b[2][5] = 200*p**6*q**11 - 250*p**3*q**13 - 10800*q**15 - 3900*p**7*q**9*r - 3325*p**4*q**11*r + 181800*p*q**13*r + 26950*p**8*q**7*r**2 + 69625*p**5*q**9*r**2 - 1214450*p**2*q**11*r**2 - 78725*p**9*q**5*r**3 - 368675*p**6*q**7*r**3 + 4166325*p**3*q**9*r**3 + 1131100*q**11*r**3 + 73400*p**10*q**3*r**4 + 661950*p**7*q**5*r**4 - 9151950*p**4*q**7*r**4 - 16633075*p*q**9*r**4 + 36000*p**11*q*r**5 + 135600*p**8*q**3*r**5 + 17321400*p**5*q**5*r**5 + 85338300*p**2*q**7*r**5 - 832000*p**9*q*r**6 - 21379200*p**6*q**3*r**6 - 176044000*p**3*q**5*r**6 - 1410000*q**7*r**6 + 6528000*p**7*q*r**7 + 129664000*p**4*q**3*r**7 + 47344000*p*q**5*r**7 - 21504000*p**5*q*r**8 - 115200000*p**2*q**3*r**8 + 25600000*p**3*q*r**9 + 64000000*q**3*r**9 + 15700*p**8*q**8*s + 120525*p**5*q**10*s + 113250*p**2*q**12*s - 196900*p**9*q**6*r*s - 1776925*p**6*q**8*r*s - 3062475*p**3*q**10*r*s - 4153500*q**12*r*s + 857925*p**10*q**4*r**2*s + 10562775*p**7*q**6*r**2*s + 34866250*p**4*q**8*r**2*s + 73486750*p*q**10*r**2*s - 1333800*p**11*q**2*r**3*s - 29212625*p**8*q**4*r**3*s - 168729675*p**5*q**6*r**3*s - 427230750*p**2*q**8*r**3*s + 108000*p**12*r**4*s + 30384200*p**9*q**2*r**4*s + 324535100*p**6*q**4*r**4*s + 952666750*p**3*q**6*r**4*s - 38076875*q**8*r**4*s - 4296000*p**10*r**5*s - 213606400*p**7*q**2*r**5*s - 842060000*p**4*q**4*r**5*s - 95285000*p*q**6*r**5*s + 61184000*p**8*r**6*s + 567520000*p**5*q**2*r**6*s + 547000000*p**2*q**4*r**6*s - 390912000*p**6*r**7*s - 812800000*p**3*q**2*r**7*s - 924000000*q**4*r**7*s + 1152000000*p**4*r**8*s + 800000000*p*q**2*r**8*s - 1280000000*p**2*r**9*s + 141750*p**10*q**5*s**2 - 31500*p**7*q**7*s**2 - 11325000*p**4*q**9*s**2 - 31687500*p*q**11*s**2 - 1293975*p**11*q**3*r*s**2 - 4803800*p**8*q**5*r*s**2 + 71398250*p**5*q**7*r*s**2 + 227625000*p**2*q**9*r*s**2 + 3256200*p**12*q*r**2*s**2 + 43870125*p**9*q**3*r**2*s**2 + 64581500*p**6*q**5*r**2*s**2 + 56090625*p**3*q**7*r**2*s**2 + 260218750*q**9*r**2*s**2 - 74610000*p**10*q*r**3*s**2 - 662186500*p**7*q**3*r**3*s**2 - 1987747500*p**4*q**5*r**3*s**2 - 811928125*p*q**7*r**3*s**2 + 471286000*p**8*q*r**4*s**2 + 2106040000*p**5*q**3*r**4*s**2 + 792687500*p**2*q**5*r**4*s**2 - 135120000*p**6*q*r**5*s**2 + 2479000000*p**3*q**3*r**5*s**2 + 5242250000*q**5*r**5*s**2 - 6400000000*p**4*q*r**6*s**2 - 8620000000*p*q**3*r**6*s**2 + 13280000000*p**2*q*r**7*s**2 + 1600000000*q*r**8*s**2 + 273375*p**12*q**2*s**3 - 13612500*p**9*q**4*s**3 - 177250000*p**6*q**6*s**3 - 511015625*p**3*q**8*s**3 - 320937500*q**10*s**3 - 2770200*p**13*r*s**3 + 12595500*p**10*q**2*r*s**3 + 543950000*p**7*q**4*r*s**3 + 1612281250*p**4*q**6*r*s**3 + 968125000*p*q**8*r*s**3 + 77031000*p**11*r**2*s**3 + 373218750*p**8*q**2*r**2*s**3 + 1839765625*p**5*q**4*r**2*s**3 + 1818515625*p**2*q**6*r**2*s**3 - 776745000*p**9*r**3*s**3 - 6861075000*p**6*q**2*r**3*s**3 - 20014531250*p**3*q**4*r**3*s**3 - 13747812500*q**6*r**3*s**3 + 3768000000*p**7*r**4*s**3 + 35365000000*p**4*q**2*r**4*s**3 + 34441875000*p*q**4*r**4*s**3 - 9628000000*p**5*r**5*s**3 - 63230000000*p**2*q**2*r**5*s**3 + 13600000000*p**3*r**6*s**3 - 15000000000*q**2*r**6*s**3 - 10400000000*p*r**7*s**3 - 45562500*p**11*q*s**4 - 525937500*p**8*q**3*s**4 - 1364218750*p**5*q**5*s**4 - 1382812500*p**2*q**7*s**4 + 572062500*p**9*q*r*s**4 + 2473515625*p**6*q**3*r*s**4 + 13192187500*p**3*q**5*r*s**4 + 12703125000*q**7*r*s**4 - 451406250*p**7*q*r**2*s**4 - 18153906250*p**4*q**3*r**2*s**4 - 36908203125*p*q**5*r**2*s**4 - 9069375000*p**5*q*r**3*s**4 + 79957812500*p**2*q**3*r**3*s**4 + 5512500000*p**3*q*r**4*s**4 + 50656250000*q**3*r**4*s**4 + 74750000000*p*q*r**5*s**4 + 56953125*p**10*s**5 + 1381640625*p**7*q**2*s**5 - 781250000*p**4*q**4*s**5 + 878906250*p*q**6*s**5 - 2655703125*p**8*r*s**5 - 3223046875*p**5*q**2*r*s**5 - 35117187500*p**2*q**4*r*s**5 + 26573437500*p**6*r**2*s**5 + 14785156250*p**3*q**2*r**2*s**5 - 52050781250*q**4*r**2*s**5 - 103062500000*p**4*r**3*s**5 - 281796875000*p*q**2*r**3*s**5 + 146875000000*p**2*r**4*s**5 - 37500000000*r**5*s**5 - 8789062500*p**6*q*s**6 - 3906250000*p**3*q**3*s**6 + 1464843750*q**5*s**6 + 102929687500*p**4*q*r*s**6 + 297119140625*p*q**3*r*s**6 - 217773437500*p**2*q*r**2*s**6 + 167968750000*q*r**3*s**6 + 10986328125*p**5*s**7 + 98876953125*p**2*q**2*s**7 - 188964843750*p**3*r*s**7 - 278320312500*q**2*r*s**7 + 517578125000*p*r**2*s**7 - 610351562500*p*q*s**8 + 762939453125*s**9 b[2][4] = -200*p**7*q**9 + 1850*p**4*q**11 + 21600*p*q**13 + 3200*p**8*q**7*r - 19200*p**5*q**9*r - 316350*p**2*q**11*r - 19050*p**9*q**5*r**2 + 37400*p**6*q**7*r**2 + 1759250*p**3*q**9*r**2 + 440100*q**11*r**2 + 48750*p**10*q**3*r**3 + 190200*p**7*q**5*r**3 - 4604200*p**4*q**7*r**3 - 6072800*p*q**9*r**3 - 43200*p**11*q*r**4 - 834500*p**8*q**3*r**4 + 4916000*p**5*q**5*r**4 + 27926850*p**2*q**7*r**4 + 969600*p**9*q*r**5 + 2467200*p**6*q**3*r**5 - 45393200*p**3*q**5*r**5 - 5399500*q**7*r**5 - 7283200*p**7*q*r**6 + 10536000*p**4*q**3*r**6 + 41656000*p*q**5*r**6 + 22784000*p**5*q*r**7 - 35200000*p**2*q**3*r**7 - 25600000*p**3*q*r**8 + 96000000*q**3*r**8 - 3000*p**9*q**6*s + 40400*p**6*q**8*s + 136550*p**3*q**10*s - 1647000*q**12*s + 40500*p**10*q**4*r*s - 173600*p**7*q**6*r*s - 126500*p**4*q**8*r*s + 23969250*p*q**10*r*s - 153900*p**11*q**2*r**2*s - 486150*p**8*q**4*r**2*s - 4115800*p**5*q**6*r**2*s - 112653250*p**2*q**8*r**2*s + 129600*p**12*r**3*s + 2683350*p**9*q**2*r**3*s + 10906650*p**6*q**4*r**3*s + 187289500*p**3*q**6*r**3*s + 44098750*q**8*r**3*s - 4384800*p**10*r**4*s - 35660800*p**7*q**2*r**4*s - 175420000*p**4*q**4*r**4*s - 426538750*p*q**6*r**4*s + 60857600*p**8*r**5*s + 349436000*p**5*q**2*r**5*s + 900600000*p**2*q**4*r**5*s - 429568000*p**6*r**6*s - 1511200000*p**3*q**2*r**6*s - 1286000000*q**4*r**6*s + 1472000000*p**4*r**7*s + 1440000000*p*q**2*r**7*s - 1920000000*p**2*r**8*s - 36450*p**11*q**3*s**2 - 188100*p**8*q**5*s**2 - 5504750*p**5*q**7*s**2 - 37968750*p**2*q**9*s**2 + 255150*p**12*q*r*s**2 + 2754000*p**9*q**3*r*s**2 + 49196500*p**6*q**5*r*s**2 + 323587500*p**3*q**7*r*s**2 - 83250000*q**9*r*s**2 - 465750*p**10*q*r**2*s**2 - 31881500*p**7*q**3*r**2*s**2 - 415585000*p**4*q**5*r**2*s**2 + 1054775000*p*q**7*r**2*s**2 - 96823500*p**8*q*r**3*s**2 - 701490000*p**5*q**3*r**3*s**2 - 2953531250*p**2*q**5*r**3*s**2 + 1454560000*p**6*q*r**4*s**2 + 7670500000*p**3*q**3*r**4*s**2 + 5661062500*q**5*r**4*s**2 - 7785000000*p**4*q*r**5*s**2 - 9450000000*p*q**3*r**5*s**2 + 14000000000*p**2*q*r**6*s**2 + 2400000000*q*r**7*s**2 - 437400*p**13*s**3 - 10145250*p**10*q**2*s**3 - 121912500*p**7*q**4*s**3 - 576531250*p**4*q**6*s**3 - 528593750*p*q**8*s**3 + 12939750*p**11*r*s**3 + 313368750*p**8*q**2*r*s**3 + 2171812500*p**5*q**4*r*s**3 + 2381718750*p**2*q**6*r*s**3 - 124638750*p**9*r**2*s**3 - 3001575000*p**6*q**2*r**2*s**3 - 12259375000*p**3*q**4*r**2*s**3 - 9985312500*q**6*r**2*s**3 + 384000000*p**7*r**3*s**3 + 13997500000*p**4*q**2*r**3*s**3 + 20749531250*p*q**4*r**3*s**3 - 553500000*p**5*r**4*s**3 - 41835000000*p**2*q**2*r**4*s**3 + 5420000000*p**3*r**5*s**3 - 16300000000*q**2*r**5*s**3 - 17600000000*p*r**6*s**3 - 7593750*p**9*q*s**4 + 289218750*p**6*q**3*s**4 + 3591406250*p**3*q**5*s**4 + 5992187500*q**7*s**4 + 658125000*p**7*q*r*s**4 - 269531250*p**4*q**3*r*s**4 - 15882812500*p*q**5*r*s**4 - 4785000000*p**5*q*r**2*s**4 + 54375781250*p**2*q**3*r**2*s**4 - 5668750000*p**3*q*r**3*s**4 + 35867187500*q**3*r**3*s**4 + 113875000000*p*q*r**4*s**4 - 544218750*p**8*s**5 - 5407031250*p**5*q**2*s**5 - 14277343750*p**2*q**4*s**5 + 5421093750*p**6*r*s**5 - 24941406250*p**3*q**2*r*s**5 - 25488281250*q**4*r*s**5 - 11500000000*p**4*r**2*s**5 - 231894531250*p*q**2*r**2*s**5 - 6250000000*p**2*r**3*s**5 - 43750000000*r**4*s**5 + 35449218750*p**4*q*s**6 + 137695312500*p*q**3*s**6 + 34667968750*p**2*q*r*s**6 + 202148437500*q*r**2*s**6 - 33691406250*p**3*s**7 - 214843750000*q**2*s**7 - 31738281250*p*r*s**7 b[2][3] = -800*p**5*q**9 - 5400*p**2*q**11 + 5800*p**6*q**7*r + 48750*p**3*q**9*r + 16200*q**11*r - 3000*p**7*q**5*r**2 - 108350*p**4*q**7*r**2 - 263250*p*q**9*r**2 - 60700*p**8*q**3*r**3 - 386250*p**5*q**5*r**3 + 253100*p**2*q**7*r**3 + 127800*p**9*q*r**4 + 2326700*p**6*q**3*r**4 + 6565550*p**3*q**5*r**4 - 705750*q**7*r**4 - 2903200*p**7*q*r**5 - 21218000*p**4*q**3*r**5 + 1057000*p*q**5*r**5 + 20368000*p**5*q*r**6 + 33000000*p**2*q**3*r**6 - 43200000*p**3*q*r**7 + 52000000*q**3*r**7 + 6200*p**7*q**6*s + 188250*p**4*q**8*s + 931500*p*q**10*s - 73800*p**8*q**4*r*s - 1466850*p**5*q**6*r*s - 6894000*p**2*q**8*r*s + 315900*p**9*q**2*r**2*s + 4547000*p**6*q**4*r**2*s + 20362500*p**3*q**6*r**2*s + 15018750*q**8*r**2*s - 653400*p**10*r**3*s - 13897550*p**7*q**2*r**3*s - 76757500*p**4*q**4*r**3*s - 124207500*p*q**6*r**3*s + 18567600*p**8*r**4*s + 175911000*p**5*q**2*r**4*s + 253787500*p**2*q**4*r**4*s - 183816000*p**6*r**5*s - 706900000*p**3*q**2*r**5*s - 665750000*q**4*r**5*s + 740000000*p**4*r**6*s + 890000000*p*q**2*r**6*s - 1040000000*p**2*r**7*s - 763000*p**6*q**5*s**2 - 12375000*p**3*q**7*s**2 - 40500000*q**9*s**2 + 364500*p**10*q*r*s**2 + 15537000*p**7*q**3*r*s**2 + 154392500*p**4*q**5*r*s**2 + 372206250*p*q**7*r*s**2 - 25481250*p**8*q*r**2*s**2 - 386300000*p**5*q**3*r**2*s**2 - 996343750*p**2*q**5*r**2*s**2 + 459872500*p**6*q*r**3*s**2 + 2943937500*p**3*q**3*r**3*s**2 + 2437781250*q**5*r**3*s**2 - 2883750000*p**4*q*r**4*s**2 - 4343750000*p*q**3*r**4*s**2 + 5495000000*p**2*q*r**5*s**2 + 1300000000*q*r**6*s**2 - 364500*p**11*s**3 - 13668750*p**8*q**2*s**3 - 113406250*p**5*q**4*s**3 - 159062500*p**2*q**6*s**3 + 13972500*p**9*r*s**3 + 61537500*p**6*q**2*r*s**3 - 1622656250*p**3*q**4*r*s**3 - 2720625000*q**6*r*s**3 - 201656250*p**7*r**2*s**3 + 1949687500*p**4*q**2*r**2*s**3 + 4979687500*p*q**4*r**2*s**3 + 497125000*p**5*r**3*s**3 - 11150625000*p**2*q**2*r**3*s**3 + 2982500000*p**3*r**4*s**3 - 6612500000*q**2*r**4*s**3 - 10450000000*p*r**5*s**3 + 126562500*p**7*q*s**4 + 1443750000*p**4*q**3*s**4 + 281250000*p*q**5*s**4 - 1648125000*p**5*q*r*s**4 + 11271093750*p**2*q**3*r*s**4 - 4785156250*p**3*q*r**2*s**4 + 8808593750*q**3*r**2*s**4 + 52390625000*p*q*r**3*s**4 - 611718750*p**6*s**5 - 13027343750*p**3*q**2*s**5 - 1464843750*q**4*s**5 + 6492187500*p**4*r*s**5 - 65351562500*p*q**2*r*s**5 - 13476562500*p**2*r**2*s**5 - 24218750000*r**3*s**5 + 41992187500*p**2*q*s**6 + 69824218750*q*r*s**6 - 34179687500*p*s**7 b[2][2] = -1000*p**6*q**7 - 5150*p**3*q**9 + 10800*q**11 + 11000*p**7*q**5*r + 66450*p**4*q**7*r - 127800*p*q**9*r - 41250*p**8*q**3*r**2 - 368400*p**5*q**5*r**2 + 204200*p**2*q**7*r**2 + 54000*p**9*q*r**3 + 1040950*p**6*q**3*r**3 + 2096500*p**3*q**5*r**3 + 200000*q**7*r**3 - 1140000*p**7*q*r**4 - 7691000*p**4*q**3*r**4 - 2281000*p*q**5*r**4 + 7296000*p**5*q*r**5 + 13300000*p**2*q**3*r**5 - 14400000*p**3*q*r**6 + 14000000*q**3*r**6 - 9000*p**8*q**4*s + 52100*p**5*q**6*s + 710250*p**2*q**8*s + 67500*p**9*q**2*r*s - 256100*p**6*q**4*r*s - 5753000*p**3*q**6*r*s + 292500*q**8*r*s - 162000*p**10*r**2*s - 1432350*p**7*q**2*r**2*s + 5410000*p**4*q**4*r**2*s - 7408750*p*q**6*r**2*s + 4401000*p**8*r**3*s + 24185000*p**5*q**2*r**3*s + 20781250*p**2*q**4*r**3*s - 43012000*p**6*r**4*s - 146300000*p**3*q**2*r**4*s - 165875000*q**4*r**4*s + 182000000*p**4*r**5*s + 250000000*p*q**2*r**5*s - 280000000*p**2*r**6*s + 60750*p**10*q*s**2 + 2414250*p**7*q**3*s**2 + 15770000*p**4*q**5*s**2 + 15825000*p*q**7*s**2 - 6021000*p**8*q*r*s**2 - 62252500*p**5*q**3*r*s**2 - 74718750*p**2*q**5*r*s**2 + 90888750*p**6*q*r**2*s**2 + 471312500*p**3*q**3*r**2*s**2 + 525875000*q**5*r**2*s**2 - 539375000*p**4*q*r**3*s**2 - 1030000000*p*q**3*r**3*s**2 + 1142500000*p**2*q*r**4*s**2 + 350000000*q*r**5*s**2 - 303750*p**9*s**3 - 35943750*p**6*q**2*s**3 - 331875000*p**3*q**4*s**3 - 505937500*q**6*s**3 + 8437500*p**7*r*s**3 + 530781250*p**4*q**2*r*s**3 + 1150312500*p*q**4*r*s**3 - 154500000*p**5*r**2*s**3 - 2059062500*p**2*q**2*r**2*s**3 + 1150000000*p**3*r**3*s**3 - 1343750000*q**2*r**3*s**3 - 2900000000*p*r**4*s**3 + 30937500*p**5*q*s**4 + 1166406250*p**2*q**3*s**4 - 1496875000*p**3*q*r*s**4 + 1296875000*q**3*r*s**4 + 10640625000*p*q*r**2*s**4 - 281250000*p**4*s**5 - 9746093750*p*q**2*s**5 + 1269531250*p**2*r*s**5 - 7421875000*r**2*s**5 + 15625000000*q*s**6 b[2][1] = -1600*p**4*q**7 - 10800*p*q**9 + 9800*p**5*q**5*r + 80550*p**2*q**7*r - 4600*p**6*q**3*r**2 - 112700*p**3*q**5*r**2 + 40500*q**7*r**2 - 34200*p**7*q*r**3 - 279500*p**4*q**3*r**3 - 665750*p*q**5*r**3 + 632000*p**5*q*r**4 + 3200000*p**2*q**3*r**4 - 2800000*p**3*q*r**5 + 3000000*q**3*r**5 - 18600*p**6*q**4*s - 51750*p**3*q**6*s + 405000*q**8*s + 21600*p**7*q**2*r*s - 122500*p**4*q**4*r*s - 2891250*p*q**6*r*s + 156600*p**8*r**2*s + 1569750*p**5*q**2*r**2*s + 6943750*p**2*q**4*r**2*s - 3774000*p**6*r**3*s - 27100000*p**3*q**2*r**3*s - 30187500*q**4*r**3*s + 28000000*p**4*r**4*s + 52500000*p*q**2*r**4*s - 60000000*p**2*r**5*s - 81000*p**8*q*s**2 - 240000*p**5*q**3*s**2 + 937500*p**2*q**5*s**2 + 3273750*p**6*q*r*s**2 + 30406250*p**3*q**3*r*s**2 + 55687500*q**5*r*s**2 - 42187500*p**4*q*r**2*s**2 - 112812500*p*q**3*r**2*s**2 + 152500000*p**2*q*r**3*s**2 + 75000000*q*r**4*s**2 - 4218750*p**4*q**2*s**3 + 15156250*p*q**4*s**3 + 5906250*p**5*r*s**3 - 206562500*p**2*q**2*r*s**3 + 107500000*p**3*r**2*s**3 - 159375000*q**2*r**2*s**3 - 612500000*p*r**3*s**3 + 135937500*p**3*q*s**4 + 46875000*q**3*s**4 + 1175781250*p*q*r*s**4 - 292968750*p**2*s**5 - 1367187500*r*s**5 b[2][0] = -800*p**5*q**5 - 5400*p**2*q**7 + 6000*p**6*q**3*r + 51700*p**3*q**5*r + 27000*q**7*r - 10800*p**7*q*r**2 - 163250*p**4*q**3*r**2 - 285750*p*q**5*r**2 + 192000*p**5*q*r**3 + 1000000*p**2*q**3*r**3 - 800000*p**3*q*r**4 + 500000*q**3*r**4 - 10800*p**7*q**2*s - 57500*p**4*q**4*s + 67500*p*q**6*s + 32400*p**8*r*s + 279000*p**5*q**2*r*s - 131250*p**2*q**4*r*s - 729000*p**6*r**2*s - 4100000*p**3*q**2*r**2*s - 5343750*q**4*r**2*s + 5000000*p**4*r**3*s + 10000000*p*q**2*r**3*s - 10000000*p**2*r**4*s + 641250*p**6*q*s**2 + 5812500*p**3*q**3*s**2 + 10125000*q**5*s**2 - 7031250*p**4*q*r*s**2 - 20625000*p*q**3*r*s**2 + 17500000*p**2*q*r**2*s**2 + 12500000*q*r**3*s**2 - 843750*p**5*s**3 - 19375000*p**2*q**2*s**3 + 30000000*p**3*r*s**3 - 20312500*q**2*r*s**3 - 112500000*p*r**2*s**3 + 183593750*p*q*s**4 - 292968750*s**5 b[3][5] = 500*p**11*q**6 + 9875*p**8*q**8 + 42625*p**5*q**10 - 35000*p**2*q**12 - 4500*p**12*q**4*r - 108375*p**9*q**6*r - 516750*p**6*q**8*r + 1110500*p**3*q**10*r + 2730000*q**12*r + 10125*p**13*q**2*r**2 + 358250*p**10*q**4*r**2 + 1908625*p**7*q**6*r**2 - 11744250*p**4*q**8*r**2 - 43383250*p*q**10*r**2 - 313875*p**11*q**2*r**3 - 2074875*p**8*q**4*r**3 + 52094750*p**5*q**6*r**3 + 264567500*p**2*q**8*r**3 + 796125*p**9*q**2*r**4 - 92486250*p**6*q**4*r**4 - 757957500*p**3*q**6*r**4 - 29354375*q**8*r**4 + 60970000*p**7*q**2*r**5 + 1112462500*p**4*q**4*r**5 + 571094375*p*q**6*r**5 - 685290000*p**5*q**2*r**6 - 2037800000*p**2*q**4*r**6 + 2279600000*p**3*q**2*r**7 + 849000000*q**4*r**7 - 1480000000*p*q**2*r**8 + 13500*p**13*q**3*s + 363000*p**10*q**5*s + 2861250*p**7*q**7*s + 8493750*p**4*q**9*s + 17031250*p*q**11*s - 60750*p**14*q*r*s - 2319750*p**11*q**3*r*s - 22674250*p**8*q**5*r*s - 74368750*p**5*q**7*r*s - 170578125*p**2*q**9*r*s + 2760750*p**12*q*r**2*s + 46719000*p**9*q**3*r**2*s + 163356375*p**6*q**5*r**2*s + 360295625*p**3*q**7*r**2*s - 195990625*q**9*r**2*s - 37341750*p**10*q*r**3*s - 194739375*p**7*q**3*r**3*s - 105463125*p**4*q**5*r**3*s - 415825000*p*q**7*r**3*s + 90180000*p**8*q*r**4*s - 990552500*p**5*q**3*r**4*s + 3519212500*p**2*q**5*r**4*s + 1112220000*p**6*q*r**5*s - 4508750000*p**3*q**3*r**5*s - 8159500000*q**5*r**5*s - 4356000000*p**4*q*r**6*s + 14615000000*p*q**3*r**6*s - 2160000000*p**2*q*r**7*s + 91125*p**15*s**2 + 3290625*p**12*q**2*s**2 + 35100000*p**9*q**4*s**2 + 175406250*p**6*q**6*s**2 + 629062500*p**3*q**8*s**2 + 910937500*q**10*s**2 - 5710500*p**13*r*s**2 - 100423125*p**10*q**2*r*s**2 - 604743750*p**7*q**4*r*s**2 - 2954843750*p**4*q**6*r*s**2 - 4587578125*p*q**8*r*s**2 + 116194500*p**11*r**2*s**2 + 1280716250*p**8*q**2*r**2*s**2 + 7401190625*p**5*q**4*r**2*s**2 + 11619937500*p**2*q**6*r**2*s**2 - 952173125*p**9*r**3*s**2 - 6519712500*p**6*q**2*r**3*s**2 - 10238593750*p**3*q**4*r**3*s**2 + 29984609375*q**6*r**3*s**2 + 2558300000*p**7*r**4*s**2 + 16225000000*p**4*q**2*r**4*s**2 - 64994140625*p*q**4*r**4*s**2 + 4202250000*p**5*r**5*s**2 + 46925000000*p**2*q**2*r**5*s**2 - 28950000000*p**3*r**6*s**2 - 1000000000*q**2*r**6*s**2 + 37000000000*p*r**7*s**2 - 48093750*p**11*q*s**3 - 673359375*p**8*q**3*s**3 - 2170312500*p**5*q**5*s**3 - 2466796875*p**2*q**7*s**3 + 647578125*p**9*q*r*s**3 + 597031250*p**6*q**3*r*s**3 - 7542578125*p**3*q**5*r*s**3 - 41125000000*q**7*r*s**3 - 2175828125*p**7*q*r**2*s**3 - 7101562500*p**4*q**3*r**2*s**3 + 100596875000*p*q**5*r**2*s**3 - 8984687500*p**5*q*r**3*s**3 - 120070312500*p**2*q**3*r**3*s**3 + 57343750000*p**3*q*r**4*s**3 + 9500000000*q**3*r**4*s**3 - 342875000000*p*q*r**5*s**3 + 400781250*p**10*s**4 + 8531250000*p**7*q**2*s**4 + 34033203125*p**4*q**4*s**4 + 42724609375*p*q**6*s**4 - 6289453125*p**8*r*s**4 - 24037109375*p**5*q**2*r*s**4 - 62626953125*p**2*q**4*r*s**4 + 17299218750*p**6*r**2*s**4 + 108357421875*p**3*q**2*r**2*s**4 - 55380859375*q**4*r**2*s**4 + 105648437500*p**4*r**3*s**4 + 1204228515625*p*q**2*r**3*s**4 - 365000000000*p**2*r**4*s**4 + 184375000000*r**5*s**4 - 32080078125*p**6*q*s**5 - 98144531250*p**3*q**3*s**5 + 93994140625*q**5*s**5 - 178955078125*p**4*q*r*s**5 - 1299804687500*p*q**3*r*s**5 + 332421875000*p**2*q*r**2*s**5 - 1195312500000*q*r**3*s**5 + 72021484375*p**5*s**6 + 323486328125*p**2*q**2*s**6 + 682373046875*p**3*r*s**6 + 2447509765625*q**2*r*s**6 - 3011474609375*p*r**2*s**6 + 3051757812500*p*q*s**7 - 7629394531250*s**8 b[3][4] = 1500*p**9*q**6 + 69625*p**6*q**8 + 590375*p**3*q**10 + 1035000*q**12 - 13500*p**10*q**4*r - 760625*p**7*q**6*r - 7904500*p**4*q**8*r - 18169250*p*q**10*r + 30375*p**11*q**2*r**2 + 2628625*p**8*q**4*r**2 + 37879000*p**5*q**6*r**2 + 121367500*p**2*q**8*r**2 - 2699250*p**9*q**2*r**3 - 76776875*p**6*q**4*r**3 - 403583125*p**3*q**6*r**3 - 78865625*q**8*r**3 + 60907500*p**7*q**2*r**4 + 735291250*p**4*q**4*r**4 + 781142500*p*q**6*r**4 - 558270000*p**5*q**2*r**5 - 2150725000*p**2*q**4*r**5 + 2015400000*p**3*q**2*r**6 + 1181000000*q**4*r**6 - 2220000000*p*q**2*r**7 + 40500*p**11*q**3*s + 1376500*p**8*q**5*s + 9953125*p**5*q**7*s + 9765625*p**2*q**9*s - 182250*p**12*q*r*s - 8859000*p**9*q**3*r*s - 82854500*p**6*q**5*r*s - 71511250*p**3*q**7*r*s + 273631250*q**9*r*s + 10233000*p**10*q*r**2*s + 179627500*p**7*q**3*r**2*s + 25164375*p**4*q**5*r**2*s - 2927290625*p*q**7*r**2*s - 171305000*p**8*q*r**3*s - 544768750*p**5*q**3*r**3*s + 7583437500*p**2*q**5*r**3*s + 1139860000*p**6*q*r**4*s - 6489375000*p**3*q**3*r**4*s - 9625375000*q**5*r**4*s - 1838000000*p**4*q*r**5*s + 19835000000*p*q**3*r**5*s - 3240000000*p**2*q*r**6*s + 273375*p**13*s**2 + 9753750*p**10*q**2*s**2 + 82575000*p**7*q**4*s**2 + 202265625*p**4*q**6*s**2 + 556093750*p*q**8*s**2 - 11552625*p**11*r*s**2 - 115813125*p**8*q**2*r*s**2 + 630590625*p**5*q**4*r*s**2 + 1347015625*p**2*q**6*r*s**2 + 157578750*p**9*r**2*s**2 - 689206250*p**6*q**2*r**2*s**2 - 4299609375*p**3*q**4*r**2*s**2 + 23896171875*q**6*r**2*s**2 - 1022437500*p**7*r**3*s**2 + 6648125000*p**4*q**2*r**3*s**2 - 52895312500*p*q**4*r**3*s**2 + 4401750000*p**5*r**4*s**2 + 26500000000*p**2*q**2*r**4*s**2 - 22125000000*p**3*r**5*s**2 - 1500000000*q**2*r**5*s**2 + 55500000000*p*r**6*s**2 - 137109375*p**9*q*s**3 - 1955937500*p**6*q**3*s**3 - 6790234375*p**3*q**5*s**3 - 16996093750*q**7*s**3 + 2146218750*p**7*q*r*s**3 + 6570312500*p**4*q**3*r*s**3 + 39918750000*p*q**5*r*s**3 - 7673281250*p**5*q*r**2*s**3 - 52000000000*p**2*q**3*r**2*s**3 + 50796875000*p**3*q*r**3*s**3 + 18750000000*q**3*r**3*s**3 - 399875000000*p*q*r**4*s**3 + 780468750*p**8*s**4 + 14455078125*p**5*q**2*s**4 + 10048828125*p**2*q**4*s**4 - 15113671875*p**6*r*s**4 + 39298828125*p**3*q**2*r*s**4 - 52138671875*q**4*r*s**4 + 45964843750*p**4*r**2*s**4 + 914414062500*p*q**2*r**2*s**4 + 1953125000*p**2*r**3*s**4 + 334375000000*r**4*s**4 - 149169921875*p**4*q*s**5 - 459716796875*p*q**3*s**5 - 325585937500*p**2*q*r*s**5 - 1462890625000*q*r**2*s**5 + 296630859375*p**3*s**6 + 1324462890625*q**2*s**6 + 307617187500*p*r*s**6 b[3][3] = -20750*p**7*q**6 - 290125*p**4*q**8 - 993000*p*q**10 + 146125*p**8*q**4*r + 2721500*p**5*q**6*r + 11833750*p**2*q**8*r - 237375*p**9*q**2*r**2 - 8167500*p**6*q**4*r**2 - 54605625*p**3*q**6*r**2 - 23802500*q**8*r**2 + 8927500*p**7*q**2*r**3 + 131184375*p**4*q**4*r**3 + 254695000*p*q**6*r**3 - 121561250*p**5*q**2*r**4 - 728003125*p**2*q**4*r**4 + 702550000*p**3*q**2*r**5 + 597312500*q**4*r**5 - 1202500000*p*q**2*r**6 - 194625*p**9*q**3*s - 1568875*p**6*q**5*s + 9685625*p**3*q**7*s + 74662500*q**9*s + 327375*p**10*q*r*s + 1280000*p**7*q**3*r*s - 123703750*p**4*q**5*r*s - 850121875*p*q**7*r*s - 7436250*p**8*q*r**2*s + 164820000*p**5*q**3*r**2*s + 2336659375*p**2*q**5*r**2*s + 32202500*p**6*q*r**3*s - 2429765625*p**3*q**3*r**3*s - 4318609375*q**5*r**3*s + 148000000*p**4*q*r**4*s + 9902812500*p*q**3*r**4*s - 1755000000*p**2*q*r**5*s + 1154250*p**11*s**2 + 36821250*p**8*q**2*s**2 + 372825000*p**5*q**4*s**2 + 1170921875*p**2*q**6*s**2 - 38913750*p**9*r*s**2 - 797071875*p**6*q**2*r*s**2 - 2848984375*p**3*q**4*r*s**2 + 7651406250*q**6*r*s**2 + 415068750*p**7*r**2*s**2 + 3151328125*p**4*q**2*r**2*s**2 - 17696875000*p*q**4*r**2*s**2 - 725968750*p**5*r**3*s**2 + 5295312500*p**2*q**2*r**3*s**2 - 8581250000*p**3*r**4*s**2 - 812500000*q**2*r**4*s**2 + 30062500000*p*r**5*s**2 - 110109375*p**7*q*s**3 - 1976562500*p**4*q**3*s**3 - 6329296875*p*q**5*s**3 + 2256328125*p**5*q*r*s**3 + 8554687500*p**2*q**3*r*s**3 + 12947265625*p**3*q*r**2*s**3 + 7984375000*q**3*r**2*s**3 - 167039062500*p*q*r**3*s**3 + 1181250000*p**6*s**4 + 17873046875*p**3*q**2*s**4 - 20449218750*q**4*s**4 - 16265625000*p**4*r*s**4 + 260869140625*p*q**2*r*s**4 + 21025390625*p**2*r**2*s**4 + 207617187500*r**3*s**4 - 207177734375*p**2*q*s**5 - 615478515625*q*r*s**5 + 301513671875*p*s**6 b[3][2] = 53125*p**5*q**6 + 425000*p**2*q**8 - 394375*p**6*q**4*r - 4301875*p**3*q**6*r - 3225000*q**8*r + 851250*p**7*q**2*r**2 + 16910625*p**4*q**4*r**2 + 44210000*p*q**6*r**2 - 20474375*p**5*q**2*r**3 - 147190625*p**2*q**4*r**3 + 163975000*p**3*q**2*r**4 + 156812500*q**4*r**4 - 323750000*p*q**2*r**5 - 99375*p**7*q**3*s - 6395000*p**4*q**5*s - 49243750*p*q**7*s - 1164375*p**8*q*r*s + 4465625*p**5*q**3*r*s + 205546875*p**2*q**5*r*s + 12163750*p**6*q*r**2*s - 315546875*p**3*q**3*r**2*s - 946453125*q**5*r**2*s - 23500000*p**4*q*r**3*s + 2313437500*p*q**3*r**3*s - 472500000*p**2*q*r**4*s + 1316250*p**9*s**2 + 22715625*p**6*q**2*s**2 + 206953125*p**3*q**4*s**2 + 1220000000*q**6*s**2 - 20953125*p**7*r*s**2 - 277656250*p**4*q**2*r*s**2 - 3317187500*p*q**4*r*s**2 + 293734375*p**5*r**2*s**2 + 1351562500*p**2*q**2*r**2*s**2 - 2278125000*p**3*r**3*s**2 - 218750000*q**2*r**3*s**2 + 8093750000*p*r**4*s**2 - 9609375*p**5*q*s**3 + 240234375*p**2*q**3*s**3 + 2310546875*p**3*q*r*s**3 + 1171875000*q**3*r*s**3 - 33460937500*p*q*r**2*s**3 + 2185546875*p**4*s**4 + 32578125000*p*q**2*s**4 - 8544921875*p**2*r*s**4 + 58398437500*r**2*s**4 - 114013671875*q*s**5 b[3][1] = -16250*p**6*q**4 - 191875*p**3*q**6 - 495000*q**8 + 73125*p**7*q**2*r + 1437500*p**4*q**4*r + 5866250*p*q**6*r - 2043125*p**5*q**2*r**2 - 17218750*p**2*q**4*r**2 + 19106250*p**3*q**2*r**3 + 34015625*q**4*r**3 - 69375000*p*q**2*r**4 - 219375*p**8*q*s - 2846250*p**5*q**3*s - 8021875*p**2*q**5*s + 3420000*p**6*q*r*s - 1640625*p**3*q**3*r*s - 152468750*q**5*r*s + 3062500*p**4*q*r**2*s + 381171875*p*q**3*r**2*s - 101250000*p**2*q*r**3*s + 2784375*p**7*s**2 + 43515625*p**4*q**2*s**2 + 115625000*p*q**4*s**2 - 48140625*p**5*r*s**2 - 307421875*p**2*q**2*r*s**2 - 25781250*p**3*r**2*s**2 - 46875000*q**2*r**2*s**2 + 1734375000*p*r**3*s**2 - 128906250*p**3*q*s**3 + 339843750*q**3*s**3 - 4583984375*p*q*r*s**3 + 2236328125*p**2*s**4 + 12255859375*r*s**4 b[3][0] = 31875*p**4*q**4 + 255000*p*q**6 - 82500*p**5*q**2*r - 1106250*p**2*q**4*r + 1653125*p**3*q**2*r**2 + 5187500*q**4*r**2 - 11562500*p*q**2*r**3 - 118125*p**6*q*s - 3593750*p**3*q**3*s - 23812500*q**5*s + 4656250*p**4*q*r*s + 67109375*p*q**3*r*s - 16875000*p**2*q*r**2*s - 984375*p**5*s**2 - 19531250*p**2*q**2*s**2 - 37890625*p**3*r*s**2 - 7812500*q**2*r*s**2 + 289062500*p*r**2*s**2 - 529296875*p*q*s**3 + 2343750000*s**4 b[4][5] = 600*p**10*q**10 + 13850*p**7*q**12 + 106150*p**4*q**14 + 270000*p*q**16 - 9300*p**11*q**8*r - 234075*p**8*q**10*r - 1942825*p**5*q**12*r - 5319900*p**2*q**14*r + 52050*p**12*q**6*r**2 + 1481025*p**9*q**8*r**2 + 13594450*p**6*q**10*r**2 + 40062750*p**3*q**12*r**2 - 3569400*q**14*r**2 - 122175*p**13*q**4*r**3 - 4260350*p**10*q**6*r**3 - 45052375*p**7*q**8*r**3 - 142634900*p**4*q**10*r**3 + 54186350*p*q**12*r**3 + 97200*p**14*q**2*r**4 + 5284225*p**11*q**4*r**4 + 70389525*p**8*q**6*r**4 + 232732850*p**5*q**8*r**4 - 318849400*p**2*q**10*r**4 - 2046000*p**12*q**2*r**5 - 43874125*p**9*q**4*r**5 - 107411850*p**6*q**6*r**5 + 948310700*p**3*q**8*r**5 - 34763575*q**10*r**5 + 5915600*p**10*q**2*r**6 - 115887800*p**7*q**4*r**6 - 1649542400*p**4*q**6*r**6 + 224468875*p*q**8*r**6 + 120252800*p**8*q**2*r**7 + 1779902000*p**5*q**4*r**7 - 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3906250000*p**3*q**2*r*s**6 - 1275878906250*q**4*r*s**6 - 121093750000*p**4*r**2*s**6 - 3308593750000*p*q**2*r**2*s**6 + 18066406250*p**2*r**3*s**6 - 244140625000*r**4*s**6 + 327148437500*p**4*q*s**7 + 1672363281250*p*q**3*s**7 + 446777343750*p**2*q*r*s**7 + 1232910156250*q*r**2*s**7 - 274658203125*p**3*s**8 - 1068115234375*q**2*s**8 - 61035156250*p*r*s**8 b[4][3] = 200*p**9*q**8 + 7550*p**6*q**10 + 78650*p**3*q**12 + 248400*q**14 - 4800*p**10*q**6*r - 164300*p**7*q**8*r - 1709575*p**4*q**10*r - 5566500*p*q**12*r + 31050*p**11*q**4*r**2 + 1116175*p**8*q**6*r**2 + 12674650*p**5*q**8*r**2 + 45333850*p**2*q**10*r**2 - 60750*p**12*q**2*r**3 - 2872725*p**9*q**4*r**3 - 40403050*p**6*q**6*r**3 - 173564375*p**3*q**8*r**3 - 11242250*q**10*r**3 + 2174100*p**10*q**2*r**4 + 54010000*p**7*q**4*r**4 + 331074875*p**4*q**6*r**4 + 114173750*p*q**8*r**4 - 24858500*p**8*q**2*r**5 - 300875000*p**5*q**4*r**5 - 319430625*p**2*q**6*r**5 + 69810000*p**6*q**2*r**6 - 23900000*p**3*q**4*r**6 - 294662500*q**6*r**6 + 524200000*p**4*q**2*r**7 + 1432000000*p*q**4*r**7 - 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8743359375*p**3*q**6*r**2*s**2 - 4154375000*q**8*r**2*s**2 - 296559000*p**10*r**3*s**2 - 4065056250*p**7*q**2*r**3*s**2 - 186328125*p**4*q**4*r**3*s**2 + 19419453125*p*q**6*r**3*s**2 + 2326262500*p**8*r**4*s**2 + 21189375000*p**5*q**2*r**4*s**2 - 26301953125*p**2*q**4*r**4*s**2 - 10513250000*p**6*r**5*s**2 - 69937500000*p**3*q**2*r**5*s**2 - 42257812500*q**4*r**5*s**2 + 23375000000*p**4*r**6*s**2 + 40750000000*p*q**2*r**6*s**2 - 19500000000*p**2*r**7*s**2 + 4009500*p**12*q*s**3 + 36140625*p**9*q**3*s**3 - 335459375*p**6*q**5*s**3 - 2695312500*p**3*q**7*s**3 - 1486250000*q**9*s**3 + 102515625*p**10*q*r*s**3 + 4006812500*p**7*q**3*r*s**3 + 27589609375*p**4*q**5*r*s**3 + 20195312500*p*q**7*r*s**3 - 2792812500*p**8*q*r**2*s**3 - 44115156250*p**5*q**3*r**2*s**3 - 72609453125*p**2*q**5*r**2*s**3 + 18752500000*p**6*q*r**3*s**3 + 218140625000*p**3*q**3*r**3*s**3 + 109940234375*q**5*r**3*s**3 - 21893750000*p**4*q*r**4*s**3 - 65187500000*p*q**3*r**4*s**3 - 31000000000*p**2*q*r**5*s**3 + 97500000000*q*r**6*s**3 - 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174000*p**4*q**10 - 518400*p*q**12 + 5400*p**11*q**4*r + 197550*p**8*q**6*r + 2147775*p**5*q**8*r + 7219800*p**2*q**10*r - 12150*p**12*q**2*r**2 - 662200*p**9*q**4*r**2 - 9274775*p**6*q**6*r**2 - 38330625*p**3*q**8*r**2 - 5508000*q**10*r**2 + 656550*p**10*q**2*r**3 + 16233750*p**7*q**4*r**3 + 97335875*p**4*q**6*r**3 + 58271250*p*q**8*r**3 - 9845500*p**8*q**2*r**4 - 119464375*p**5*q**4*r**4 - 194431875*p**2*q**6*r**4 + 49465000*p**6*q**2*r**5 + 166000000*p**3*q**4*r**5 - 80793750*q**6*r**5 + 54400000*p**4*q**2*r**6 + 377750000*p*q**4*r**6 - 630000000*p**2*q**2*r**7 - 16200*p**12*q**3*s - 459300*p**9*q**5*s - 4207225*p**6*q**7*s - 10827500*p**3*q**9*s + 13635000*q**11*s + 72900*p**13*q*r*s + 2877300*p**10*q**3*r*s + 33239700*p**7*q**5*r*s + 107080625*p**4*q**7*r*s - 114975000*p*q**9*r*s - 3601800*p**11*q*r**2*s - 75214375*p**8*q**3*r**2*s - 387073250*p**5*q**5*r**2*s + 55540625*p**2*q**7*r**2*s + 53793000*p**9*q*r**3*s + 687176875*p**6*q**3*r**3*s + 1670018750*p**3*q**5*r**3*s + 665234375*q**7*r**3*s - 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11642812500*p**2*q**5*r*s**3 + 2553203125*p**6*q*r**2*s**3 + 37234375000*p**3*q**3*r**2*s**3 + 21871484375*q**5*r**2*s**3 + 2803125000*p**4*q*r**3*s**3 - 10796875000*p*q**3*r**3*s**3 - 16656250000*p**2*q*r**4*s**3 + 26250000000*q*r**5*s**3 - 75937500*p**9*s**4 - 704062500*p**6*q**2*s**4 - 8363281250*p**3*q**4*s**4 - 10398437500*q**6*s**4 + 197578125*p**7*r*s**4 - 16441406250*p**4*q**2*r*s**4 - 24277343750*p*q**4*r*s**4 - 5716015625*p**5*r**2*s**4 + 31728515625*p**2*q**2*r**2*s**4 + 27031250000*p**3*r**3*s**4 - 92285156250*q**2*r**3*s**4 - 33593750000*p*r**4*s**4 + 10394531250*p**5*q*s**5 + 38037109375*p**2*q**3*s**5 - 48144531250*p**3*q*r*s**5 + 74462890625*q**3*r*s**5 + 121093750000*p*q*r**2*s**5 - 2197265625*p**4*s**6 - 92529296875*p*q**2*s**6 + 15380859375*p**2*r*s**6 - 31738281250*r**2*s**6 + 54931640625*q*s**7 b[4][1] = 200*p**8*q**6 + 2950*p**5*q**8 + 10800*p**2*q**10 - 1800*p**9*q**4*r - 49650*p**6*q**6*r - 403375*p**3*q**8*r - 999000*q**10*r + 4050*p**10*q**2*r**2 + 236625*p**7*q**4*r**2 + 3109500*p**4*q**6*r**2 + 11463750*p*q**8*r**2 - 331500*p**8*q**2*r**3 - 7818125*p**5*q**4*r**3 - 41411250*p**2*q**6*r**3 + 4782500*p**6*q**2*r**4 + 47475000*p**3*q**4*r**4 - 16728125*q**6*r**4 - 8700000*p**4*q**2*r**5 + 81750000*p*q**4*r**5 - 135000000*p**2*q**2*r**6 + 5400*p**10*q**3*s + 144200*p**7*q**5*s + 939375*p**4*q**7*s + 1012500*p*q**9*s - 24300*p**11*q*r*s - 1169250*p**8*q**3*r*s - 14027250*p**5*q**5*r*s - 44446875*p**2*q**7*r*s + 2011500*p**9*q*r**2*s + 49330625*p**6*q**3*r**2*s + 272009375*p**3*q**5*r**2*s + 104062500*q**7*r**2*s - 34660000*p**7*q*r**3*s - 455062500*p**4*q**3*r**3*s - 625906250*p*q**5*r**3*s + 210200000*p**5*q*r**4*s + 1298750000*p**2*q**3*r**4*s - 240000000*p**3*q*r**5*s + 225000000*q**3*r**5*s + 36450*p**12*s**2 + 1231875*p**9*q**2*s**2 + 10712500*p**6*q**4*s**2 + 21718750*p**3*q**6*s**2 + 16875000*q**8*s**2 - 2814750*p**10*r*s**2 - 67612500*p**7*q**2*r*s**2 - 345156250*p**4*q**4*r*s**2 - 283125000*p*q**6*r*s**2 + 51300000*p**8*r**2*s**2 + 734531250*p**5*q**2*r**2*s**2 + 1267187500*p**2*q**4*r**2*s**2 - 384312500*p**6*r**3*s**2 - 3912500000*p**3*q**2*r**3*s**2 - 1822265625*q**4*r**3*s**2 + 1112500000*p**4*r**4*s**2 + 2437500000*p*q**2*r**4*s**2 - 1125000000*p**2*r**5*s**2 - 72578125*p**5*q**3*s**3 - 189296875*p**2*q**5*s**3 + 127265625*p**6*q*r*s**3 + 1415625000*p**3*q**3*r*s**3 + 1229687500*q**5*r*s**3 + 1448437500*p**4*q*r**2*s**3 + 2218750000*p*q**3*r**2*s**3 - 4031250000*p**2*q*r**3*s**3 + 5625000000*q*r**4*s**3 - 132890625*p**7*s**4 - 529296875*p**4*q**2*s**4 - 175781250*p*q**4*s**4 - 401953125*p**5*r*s**4 - 4482421875*p**2*q**2*r*s**4 + 4140625000*p**3*r**2*s**4 - 10498046875*q**2*r**2*s**4 - 7031250000*p*r**3*s**4 + 1220703125*p**3*q*s**5 + 1953125000*q**3*s**5 + 14160156250*p*q*r*s**5 - 1708984375*p**2*s**6 - 3662109375*r*s**6 b[4][0] = -4600*p**6*q**6 - 67850*p**3*q**8 - 248400*q**10 + 38900*p**7*q**4*r + 679575*p**4*q**6*r + 2866500*p*q**8*r - 81900*p**8*q**2*r**2 - 2009750*p**5*q**4*r**2 - 10783750*p**2*q**6*r**2 + 1478750*p**6*q**2*r**3 + 14165625*p**3*q**4*r**3 - 2743750*q**6*r**3 - 5450000*p**4*q**2*r**4 + 12687500*p*q**4*r**4 - 22500000*p**2*q**2*r**5 - 101700*p**8*q**3*s - 1700975*p**5*q**5*s - 7061250*p**2*q**7*s + 423900*p**9*q*r*s + 9292375*p**6*q**3*r*s + 50438750*p**3*q**5*r*s + 20475000*q**7*r*s - 7852500*p**7*q*r**2*s - 87765625*p**4*q**3*r**2*s - 121609375*p*q**5*r**2*s + 47700000*p**5*q*r**3*s + 264687500*p**2*q**3*r**3*s - 65000000*p**3*q*r**4*s + 37500000*q**3*r**4*s - 534600*p**10*s**2 - 10344375*p**7*q**2*s**2 - 54859375*p**4*q**4*s**2 - 40312500*p*q**6*s**2 + 10158750*p**8*r*s**2 + 117778125*p**5*q**2*r*s**2 + 192421875*p**2*q**4*r*s**2 - 70593750*p**6*r**2*s**2 - 685312500*p**3*q**2*r**2*s**2 - 334375000*q**4*r**2*s**2 + 193750000*p**4*r**3*s**2 + 500000000*p*q**2*r**3*s**2 - 187500000*p**2*r**4*s**2 + 8437500*p**6*q*s**3 + 159218750*p**3*q**3*s**3 + 220625000*q**5*s**3 + 353828125*p**4*q*r*s**3 + 412500000*p*q**3*r*s**3 - 1023437500*p**2*q*r**2*s**3 + 937500000*q*r**3*s**3 - 206015625*p**5*s**4 - 701171875*p**2*q**2*s**4 + 998046875*p**3*r*s**4 - 1308593750*q**2*r*s**4 - 1367187500*p*r**2*s**4 + 1708984375*p*q*s**5 - 976562500*s**6 return b @property def o(self): p, q, r, s = self.p, self.q, self.r, self.s o = [0]*6 o[5] = -1600*p**10*q**10 - 23600*p**7*q**12 - 86400*p**4*q**14 + 24800*p**11*q**8*r + 419200*p**8*q**10*r + 1850450*p**5*q**12*r + 896400*p**2*q**14*r - 138800*p**12*q**6*r**2 - 2921900*p**9*q**8*r**2 - 17295200*p**6*q**10*r**2 - 27127750*p**3*q**12*r**2 - 26076600*q**14*r**2 + 325800*p**13*q**4*r**3 + 9993850*p**10*q**6*r**3 + 88010500*p**7*q**8*r**3 + 274047650*p**4*q**10*r**3 + 410171400*p*q**12*r**3 - 259200*p**14*q**2*r**4 - 17147100*p**11*q**4*r**4 - 254289150*p**8*q**6*r**4 - 1318548225*p**5*q**8*r**4 - 2633598475*p**2*q**10*r**4 + 12636000*p**12*q**2*r**5 + 388911000*p**9*q**4*r**5 + 3269704725*p**6*q**6*r**5 + 8791192300*p**3*q**8*r**5 + 93560575*q**10*r**5 - 228361600*p**10*q**2*r**6 - 3951199200*p**7*q**4*r**6 - 16276981100*p**4*q**6*r**6 - 1597227000*p*q**8*r**6 + 1947899200*p**8*q**2*r**7 + 17037648000*p**5*q**4*r**7 + 8919740000*p**2*q**6*r**7 - 7672160000*p**6*q**2*r**8 - 15496000000*p**3*q**4*r**8 + 4224000000*q**6*r**8 + 9968000000*p**4*q**2*r**9 - 8640000000*p*q**4*r**9 + 4800000000*p**2*q**2*r**10 - 55200*p**12*q**7*s - 685600*p**9*q**9*s + 1028250*p**6*q**11*s + 37650000*p**3*q**13*s + 111375000*q**15*s + 583200*p**13*q**5*r*s + 9075600*p**10*q**7*r*s - 883150*p**7*q**9*r*s - 506830750*p**4*q**11*r*s - 1793137500*p*q**13*r*s - 1852200*p**14*q**3*r**2*s - 41435250*p**11*q**5*r**2*s - 80566700*p**8*q**7*r**2*s + 2485673600*p**5*q**9*r**2*s + 11442286125*p**2*q**11*r**2*s + 1555200*p**15*q*r**3*s + 80846100*p**12*q**3*r**3*s + 564906800*p**9*q**5*r**3*s - 4493012400*p**6*q**7*r**3*s - 35492391250*p**3*q**9*r**3*s - 789931875*q**11*r**3*s - 71766000*p**13*q*r**4*s - 1551149200*p**10*q**3*r**4*s - 1773437900*p**7*q**5*r**4*s + 51957593125*p**4*q**7*r**4*s + 14964765625*p*q**9*r**4*s + 1231569600*p**11*q*r**5*s + 12042977600*p**8*q**3*r**5*s - 27151011200*p**5*q**5*r**5*s - 88080610000*p**2*q**7*r**5*s - 9912995200*p**9*q*r**6*s - 29448104000*p**6*q**3*r**6*s + 144954840000*p**3*q**5*r**6*s - 44601300000*q**7*r**6*s + 35453760000*p**7*q*r**7*s - 63264000000*p**4*q**3*r**7*s + 60544000000*p*q**5*r**7*s - 30048000000*p**5*q*r**8*s + 37040000000*p**2*q**3*r**8*s - 60800000000*p**3*q*r**9*s - 48000000000*q**3*r**9*s - 615600*p**14*q**4*s**2 - 10524500*p**11*q**6*s**2 - 33831250*p**8*q**8*s**2 + 222806250*p**5*q**10*s**2 + 1099687500*p**2*q**12*s**2 + 3353400*p**15*q**2*r*s**2 + 74269350*p**12*q**4*r*s**2 + 276445750*p**9*q**6*r*s**2 - 2618600000*p**6*q**8*r*s**2 - 14473243750*p**3*q**10*r*s**2 + 1383750000*q**12*r*s**2 - 2332800*p**16*r**2*s**2 - 132750900*p**13*q**2*r**2*s**2 - 900775150*p**10*q**4*r**2*s**2 + 8249244500*p**7*q**6*r**2*s**2 + 59525796875*p**4*q**8*r**2*s**2 - 40292868750*p*q**10*r**2*s**2 + 128304000*p**14*r**3*s**2 + 3160232100*p**11*q**2*r**3*s**2 + 8329580000*p**8*q**4*r**3*s**2 - 45558458750*p**5*q**6*r**3*s**2 + 297252890625*p**2*q**8*r**3*s**2 - 2769854400*p**12*r**4*s**2 - 37065970000*p**9*q**2*r**4*s**2 - 90812546875*p**6*q**4*r**4*s**2 - 627902000000*p**3*q**6*r**4*s**2 + 181347421875*q**8*r**4*s**2 + 30946932800*p**10*r**5*s**2 + 249954680000*p**7*q**2*r**5*s**2 + 802954812500*p**4*q**4*r**5*s**2 - 80900000000*p*q**6*r**5*s**2 - 192137320000*p**8*r**6*s**2 - 932641600000*p**5*q**2*r**6*s**2 - 943242500000*p**2*q**4*r**6*s**2 + 658412000000*p**6*r**7*s**2 + 1930720000000*p**3*q**2*r**7*s**2 + 593800000000*q**4*r**7*s**2 - 1162800000000*p**4*r**8*s**2 - 280000000000*p*q**2*r**8*s**2 + 840000000000*p**2*r**9*s**2 - 2187000*p**16*q*s**3 - 47418750*p**13*q**3*s**3 - 180618750*p**10*q**5*s**3 + 2231250000*p**7*q**7*s**3 + 17857734375*p**4*q**9*s**3 + 29882812500*p*q**11*s**3 + 24664500*p**14*q*r*s**3 - 853368750*p**11*q**3*r*s**3 - 25939693750*p**8*q**5*r*s**3 - 177541562500*p**5*q**7*r*s**3 - 297978828125*p**2*q**9*r*s**3 - 153468000*p**12*q*r**2*s**3 + 30188125000*p**9*q**3*r**2*s**3 + 344049821875*p**6*q**5*r**2*s**3 + 534026875000*p**3*q**7*r**2*s**3 - 340726484375*q**9*r**2*s**3 - 9056190000*p**10*q*r**3*s**3 - 322314687500*p**7*q**3*r**3*s**3 - 769632109375*p**4*q**5*r**3*s**3 - 83276875000*p*q**7*r**3*s**3 + 164061000000*p**8*q*r**4*s**3 + 1381358750000*p**5*q**3*r**4*s**3 + 3088020000000*p**2*q**5*r**4*s**3 - 1267655000000*p**6*q*r**5*s**3 - 7642630000000*p**3*q**3*r**5*s**3 - 2759877500000*q**5*r**5*s**3 + 4597760000000*p**4*q*r**6*s**3 + 1846200000000*p*q**3*r**6*s**3 - 7006000000000*p**2*q*r**7*s**3 - 1200000000000*q*r**8*s**3 + 18225000*p**15*s**4 + 1328906250*p**12*q**2*s**4 + 24729140625*p**9*q**4*s**4 + 169467187500*p**6*q**6*s**4 + 413281250000*p**3*q**8*s**4 + 223828125000*q**10*s**4 + 710775000*p**13*r*s**4 - 18611015625*p**10*q**2*r*s**4 - 314344375000*p**7*q**4*r*s**4 - 828439843750*p**4*q**6*r*s**4 + 460937500000*p*q**8*r*s**4 - 25674975000*p**11*r**2*s**4 - 52223515625*p**8*q**2*r**2*s**4 - 387160000000*p**5*q**4*r**2*s**4 - 4733680078125*p**2*q**6*r**2*s**4 + 343911875000*p**9*r**3*s**4 + 3328658359375*p**6*q**2*r**3*s**4 + 16532406250000*p**3*q**4*r**3*s**4 + 5980613281250*q**6*r**3*s**4 - 2295497500000*p**7*r**4*s**4 - 14809820312500*p**4*q**2*r**4*s**4 - 6491406250000*p*q**4*r**4*s**4 + 7768470000000*p**5*r**5*s**4 + 34192562500000*p**2*q**2*r**5*s**4 - 11859000000000*p**3*r**6*s**4 + 10530000000000*q**2*r**6*s**4 + 6000000000000*p*r**7*s**4 + 11453906250*p**11*q*s**5 + 149765625000*p**8*q**3*s**5 + 545537109375*p**5*q**5*s**5 + 527343750000*p**2*q**7*s**5 - 371313281250*p**9*q*r*s**5 - 3461455078125*p**6*q**3*r*s**5 - 7920878906250*p**3*q**5*r*s**5 - 4747314453125*q**7*r*s**5 + 2417815625000*p**7*q*r**2*s**5 + 5465576171875*p**4*q**3*r**2*s**5 + 5937128906250*p*q**5*r**2*s**5 - 10661156250000*p**5*q*r**3*s**5 - 63574218750000*p**2*q**3*r**3*s**5 + 24059375000000*p**3*q*r**4*s**5 - 33023437500000*q**3*r**4*s**5 - 43125000000000*p*q*r**5*s**5 + 94394531250*p**10*s**6 + 1097167968750*p**7*q**2*s**6 + 2829833984375*p**4*q**4*s**6 - 1525878906250*p*q**6*s**6 + 2724609375*p**8*r*s**6 + 13998535156250*p**5*q**2*r*s**6 + 57094482421875*p**2*q**4*r*s**6 - 8512509765625*p**6*r**2*s**6 - 37941406250000*p**3*q**2*r**2*s**6 + 33191894531250*q**4*r**2*s**6 + 50534179687500*p**4*r**3*s**6 + 156656250000000*p*q**2*r**3*s**6 - 85023437500000*p**2*r**4*s**6 + 10125000000000*r**5*s**6 - 2717285156250*p**6*q*s**7 - 11352539062500*p**3*q**3*s**7 - 2593994140625*q**5*s**7 - 47154541015625*p**4*q*r*s**7 - 160644531250000*p*q**3*r*s**7 + 142500000000000*p**2*q*r**2*s**7 - 26757812500000*q*r**3*s**7 - 4364013671875*p**5*s**8 - 94604492187500*p**2*q**2*s**8 + 114379882812500*p**3*r*s**8 + 51116943359375*q**2*r*s**8 - 346435546875000*p*r**2*s**8 + 476837158203125*p*q*s**9 - 476837158203125*s**10 o[4] = 1600*p**11*q**8 + 20800*p**8*q**10 + 45100*p**5*q**12 - 151200*p**2*q**14 - 19200*p**12*q**6*r - 293200*p**9*q**8*r - 794600*p**6*q**10*r + 2634675*p**3*q**12*r + 2640600*q**14*r + 75600*p**13*q**4*r**2 + 1529100*p**10*q**6*r**2 + 6233350*p**7*q**8*r**2 - 12013350*p**4*q**10*r**2 - 29069550*p*q**12*r**2 - 97200*p**14*q**2*r**3 - 3562500*p**11*q**4*r**3 - 26984900*p**8*q**6*r**3 - 15900325*p**5*q**8*r**3 + 76267100*p**2*q**10*r**3 + 3272400*p**12*q**2*r**4 + 59486850*p**9*q**4*r**4 + 221270075*p**6*q**6*r**4 + 74065250*p**3*q**8*r**4 - 300564375*q**10*r**4 - 45569400*p**10*q**2*r**5 - 438666000*p**7*q**4*r**5 - 444821250*p**4*q**6*r**5 + 2448256250*p*q**8*r**5 + 290640000*p**8*q**2*r**6 + 855850000*p**5*q**4*r**6 - 5741875000*p**2*q**6*r**6 - 644000000*p**6*q**2*r**7 + 5574000000*p**3*q**4*r**7 + 4643000000*q**6*r**7 - 1696000000*p**4*q**2*r**8 - 12660000000*p*q**4*r**8 + 7200000000*p**2*q**2*r**9 + 43200*p**13*q**5*s + 572000*p**10*q**7*s - 59800*p**7*q**9*s - 24174625*p**4*q**11*s - 74587500*p*q**13*s - 324000*p**14*q**3*r*s - 5531400*p**11*q**5*r*s - 3712100*p**8*q**7*r*s + 293009275*p**5*q**9*r*s + 1115548875*p**2*q**11*r*s + 583200*p**15*q*r**2*s + 18343800*p**12*q**3*r**2*s + 77911100*p**9*q**5*r**2*s - 957488825*p**6*q**7*r**2*s - 5449661250*p**3*q**9*r**2*s + 960120000*q**11*r**2*s - 23684400*p**13*q*r**3*s - 373761900*p**10*q**3*r**3*s - 27944975*p**7*q**5*r**3*s + 10375740625*p**4*q**7*r**3*s - 4649093750*p*q**9*r**3*s + 395816400*p**11*q*r**4*s + 2910968000*p**8*q**3*r**4*s - 9126162500*p**5*q**5*r**4*s - 11696118750*p**2*q**7*r**4*s - 3028640000*p**9*q*r**5*s - 3251550000*p**6*q**3*r**5*s + 47914250000*p**3*q**5*r**5*s - 30255625000*q**7*r**5*s + 9304000000*p**7*q*r**6*s - 42970000000*p**4*q**3*r**6*s + 31475000000*p*q**5*r**6*s + 2176000000*p**5*q*r**7*s + 62100000000*p**2*q**3*r**7*s - 43200000000*p**3*q*r**8*s - 72000000000*q**3*r**8*s + 291600*p**15*q**2*s**2 + 2702700*p**12*q**4*s**2 - 38692250*p**9*q**6*s**2 - 538903125*p**6*q**8*s**2 - 1613112500*p**3*q**10*s**2 + 320625000*q**12*s**2 - 874800*p**16*r*s**2 - 14166900*p**13*q**2*r*s**2 + 193284900*p**10*q**4*r*s**2 + 3688520500*p**7*q**6*r*s**2 + 11613390625*p**4*q**8*r*s**2 - 15609881250*p*q**10*r*s**2 + 44031600*p**14*r**2*s**2 + 482345550*p**11*q**2*r**2*s**2 - 2020881875*p**8*q**4*r**2*s**2 - 7407026250*p**5*q**6*r**2*s**2 + 136175750000*p**2*q**8*r**2*s**2 - 1000884600*p**12*r**3*s**2 - 8888950000*p**9*q**2*r**3*s**2 - 30101703125*p**6*q**4*r**3*s**2 - 319761000000*p**3*q**6*r**3*s**2 + 51519218750*q**8*r**3*s**2 + 12622395000*p**10*r**4*s**2 + 97032450000*p**7*q**2*r**4*s**2 + 469929218750*p**4*q**4*r**4*s**2 + 291342187500*p*q**6*r**4*s**2 - 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168750000*q**8*s**2 - 2551500*p**10*r*s**2 - 5062500*p**7*q**2*r*s**2 + 712343750*p**4*q**4*r*s**2 + 4788281250*p*q**6*r*s**2 - 256837500*p**8*r**2*s**2 - 3574812500*p**5*q**2*r**2*s**2 - 14967968750*p**2*q**4*r**2*s**2 + 4040937500*p**6*r**3*s**2 + 26400000000*p**3*q**2*r**3*s**2 + 17083984375*q**4*r**3*s**2 - 21812500000*p**4*r**4*s**2 - 24375000000*p*q**2*r**4*s**2 + 39375000000*p**2*r**5*s**2 - 127265625*p**5*q**3*s**3 - 680234375*p**2*q**5*s**3 - 2048203125*p**6*q*r*s**3 - 18794531250*p**3*q**3*r*s**3 - 25050000000*q**5*r*s**3 + 26621875000*p**4*q*r**2*s**3 + 37007812500*p*q**3*r**2*s**3 - 105468750000*p**2*q*r**3*s**3 - 56250000000*q*r**4*s**3 + 1124296875*p**7*s**4 + 9251953125*p**4*q**2*s**4 - 8007812500*p*q**4*s**4 - 4004296875*p**5*r*s**4 + 179931640625*p**2*q**2*r*s**4 - 75703125000*p**3*r**2*s**4 + 133447265625*q**2*r**2*s**4 + 363281250000*p*r**3*s**4 - 91552734375*p**3*q*s**5 - 19531250000*q**3*s**5 - 751953125000*p*q*r*s**5 + 157958984375*p**2*s**6 + 748291015625*r*s**6 o[0] = -14400*p**6*q**6 - 212400*p**3*q**8 - 777600*q**10 + 92100*p**7*q**4*r + 1689675*p**4*q**6*r + 7371000*p*q**8*r - 122850*p**8*q**2*r**2 - 3735250*p**5*q**4*r**2 - 22432500*p**2*q**6*r**2 + 2298750*p**6*q**2*r**3 + 29390625*p**3*q**4*r**3 + 18000000*q**6*r**3 - 17750000*p**4*q**2*r**4 - 62812500*p*q**4*r**4 + 37500000*p**2*q**2*r**5 - 51300*p**8*q**3*s - 768025*p**5*q**5*s - 2801250*p**2*q**7*s - 275400*p**9*q*r*s - 5479875*p**6*q**3*r*s - 35538750*p**3*q**5*r*s - 68850000*q**7*r*s + 12757500*p**7*q*r**2*s + 133640625*p**4*q**3*r**2*s + 222609375*p*q**5*r**2*s - 108500000*p**5*q*r**3*s - 290312500*p**2*q**3*r**3*s + 275000000*p**3*q*r**4*s - 375000000*q**3*r**4*s + 1931850*p**10*s**2 + 40213125*p**7*q**2*s**2 + 253921875*p**4*q**4*s**2 + 464062500*p*q**6*s**2 - 71077500*p**8*r*s**2 - 818746875*p**5*q**2*r*s**2 - 1882265625*p**2*q**4*r*s**2 + 826031250*p**6*r**2*s**2 + 4369687500*p**3*q**2*r**2*s**2 + 3107812500*q**4*r**2*s**2 - 3943750000*p**4*r**3*s**2 - 5000000000*p*q**2*r**3*s**2 + 6562500000*p**2*r**4*s**2 - 295312500*p**6*q*s**3 - 2938906250*p**3*q**3*s**3 - 4848750000*q**5*s**3 + 3791484375*p**4*q*r*s**3 + 7556250000*p*q**3*r*s**3 - 11960937500*p**2*q*r**2*s**3 - 9375000000*q*r**3*s**3 + 1668515625*p**5*s**4 + 20447265625*p**2*q**2*s**4 - 21955078125*p**3*r*s**4 + 18984375000*q**2*r*s**4 + 67382812500*p*r**2*s**4 - 120849609375*p*q*s**5 + 157226562500*s**6 return o @property def a(self): p, q, r, s = self.p, self.q, self.r, self.s a = [0]*6 a[5] = -100*p**7*q**7 - 2175*p**4*q**9 - 10500*p*q**11 + 1100*p**8*q**5*r + 27975*p**5*q**7*r + 152950*p**2*q**9*r - 4125*p**9*q**3*r**2 - 128875*p**6*q**5*r**2 - 830525*p**3*q**7*r**2 + 59450*q**9*r**2 + 5400*p**10*q*r**3 + 243800*p**7*q**3*r**3 + 2082650*p**4*q**5*r**3 - 333925*p*q**7*r**3 - 139200*p**8*q*r**4 - 2406000*p**5*q**3*r**4 - 122600*p**2*q**5*r**4 + 1254400*p**6*q*r**5 + 3776000*p**3*q**3*r**5 + 1832000*q**5*r**5 - 4736000*p**4*q*r**6 - 6720000*p*q**3*r**6 + 6400000*p**2*q*r**7 - 900*p**9*q**4*s - 37400*p**6*q**6*s - 281625*p**3*q**8*s - 435000*q**10*s + 6750*p**10*q**2*r*s + 322300*p**7*q**4*r*s + 2718575*p**4*q**6*r*s + 4214250*p*q**8*r*s - 16200*p**11*r**2*s - 859275*p**8*q**2*r**2*s - 8925475*p**5*q**4*r**2*s - 14427875*p**2*q**6*r**2*s + 453600*p**9*r**3*s + 10038400*p**6*q**2*r**3*s + 17397500*p**3*q**4*r**3*s - 11333125*q**6*r**3*s - 4451200*p**7*r**4*s - 15850000*p**4*q**2*r**4*s + 34000000*p*q**4*r**4*s + 17984000*p**5*r**5*s - 10000000*p**2*q**2*r**5*s - 25600000*p**3*r**6*s - 8000000*q**2*r**6*s + 6075*p**11*q*s**2 - 83250*p**8*q**3*s**2 - 1282500*p**5*q**5*s**2 - 2862500*p**2*q**7*s**2 + 724275*p**9*q*r*s**2 + 9807250*p**6*q**3*r*s**2 + 28374375*p**3*q**5*r*s**2 + 22212500*q**7*r*s**2 - 8982000*p**7*q*r**2*s**2 - 39600000*p**4*q**3*r**2*s**2 - 61746875*p*q**5*r**2*s**2 - 1010000*p**5*q*r**3*s**2 - 1000000*p**2*q**3*r**3*s**2 + 78000000*p**3*q*r**4*s**2 + 30000000*q**3*r**4*s**2 + 80000000*p*q*r**5*s**2 - 759375*p**10*s**3 - 9787500*p**7*q**2*s**3 - 39062500*p**4*q**4*s**3 - 52343750*p*q**6*s**3 + 12301875*p**8*r*s**3 + 98175000*p**5*q**2*r*s**3 + 225078125*p**2*q**4*r*s**3 - 54900000*p**6*r**2*s**3 - 310000000*p**3*q**2*r**2*s**3 - 7890625*q**4*r**2*s**3 + 51250000*p**4*r**3*s**3 - 420000000*p*q**2*r**3*s**3 + 110000000*p**2*r**4*s**3 - 200000000*r**5*s**3 + 2109375*p**6*q*s**4 - 21093750*p**3*q**3*s**4 - 89843750*q**5*s**4 + 182343750*p**4*q*r*s**4 + 733203125*p*q**3*r*s**4 - 196875000*p**2*q*r**2*s**4 + 1125000000*q*r**3*s**4 - 158203125*p**5*s**5 - 566406250*p**2*q**2*s**5 + 101562500*p**3*r*s**5 - 1669921875*q**2*r*s**5 + 1250000000*p*r**2*s**5 - 1220703125*p*q*s**6 + 6103515625*s**7 a[4] = 1000*p**5*q**7 + 7250*p**2*q**9 - 10800*p**6*q**5*r - 96900*p**3*q**7*r - 52500*q**9*r + 37400*p**7*q**3*r**2 + 470850*p**4*q**5*r**2 + 640600*p*q**7*r**2 - 39600*p**8*q*r**3 - 983600*p**5*q**3*r**3 - 2848100*p**2*q**5*r**3 + 814400*p**6*q*r**4 + 6076000*p**3*q**3*r**4 + 2308000*q**5*r**4 - 5024000*p**4*q*r**5 - 9680000*p*q**3*r**5 + 9600000*p**2*q*r**6 + 13800*p**7*q**4*s + 94650*p**4*q**6*s - 26500*p*q**8*s - 86400*p**8*q**2*r*s - 816500*p**5*q**4*r*s - 257500*p**2*q**6*r*s + 91800*p**9*r**2*s + 1853700*p**6*q**2*r**2*s + 630000*p**3*q**4*r**2*s - 8971250*q**6*r**2*s - 2071200*p**7*r**3*s - 7240000*p**4*q**2*r**3*s + 29375000*p*q**4*r**3*s + 14416000*p**5*r**4*s - 5200000*p**2*q**2*r**4*s - 30400000*p**3*r**5*s - 12000000*q**2*r**5*s + 64800*p**9*q*s**2 + 567000*p**6*q**3*s**2 + 1655000*p**3*q**5*s**2 + 6987500*q**7*s**2 + 337500*p**7*q*r*s**2 + 8462500*p**4*q**3*r*s**2 - 5812500*p*q**5*r*s**2 - 24930000*p**5*q*r**2*s**2 - 69125000*p**2*q**3*r**2*s**2 + 103500000*p**3*q*r**3*s**2 + 30000000*q**3*r**3*s**2 + 90000000*p*q*r**4*s**2 - 708750*p**8*s**3 - 5400000*p**5*q**2*s**3 + 8906250*p**2*q**4*s**3 + 18562500*p**6*r*s**3 - 625000*p**3*q**2*r*s**3 + 29687500*q**4*r*s**3 - 75000000*p**4*r**2*s**3 - 416250000*p*q**2*r**2*s**3 + 60000000*p**2*r**3*s**3 - 300000000*r**4*s**3 + 71718750*p**4*q*s**4 + 189062500*p*q**3*s**4 + 210937500*p**2*q*r*s**4 + 1187500000*q*r**2*s**4 - 187500000*p**3*s**5 - 800781250*q**2*s**5 - 390625000*p*r*s**5 a[3] = -500*p**6*q**5 - 6350*p**3*q**7 - 19800*q**9 + 3750*p**7*q**3*r + 65100*p**4*q**5*r + 264950*p*q**7*r - 6750*p**8*q*r**2 - 209050*p**5*q**3*r**2 - 1217250*p**2*q**5*r**2 + 219000*p**6*q*r**3 + 2510000*p**3*q**3*r**3 + 1098500*q**5*r**3 - 2068000*p**4*q*r**4 - 5060000*p*q**3*r**4 + 5200000*p**2*q*r**5 - 6750*p**8*q**2*s - 96350*p**5*q**4*s - 346000*p**2*q**6*s + 20250*p**9*r*s + 459900*p**6*q**2*r*s + 1828750*p**3*q**4*r*s - 2930000*q**6*r*s - 594000*p**7*r**2*s - 4301250*p**4*q**2*r**2*s + 10906250*p*q**4*r**2*s + 5252000*p**5*r**3*s - 1450000*p**2*q**2*r**3*s - 12800000*p**3*r**4*s - 6500000*q**2*r**4*s + 74250*p**7*q*s**2 + 1418750*p**4*q**3*s**2 + 5956250*p*q**5*s**2 - 4297500*p**5*q*r*s**2 - 29906250*p**2*q**3*r*s**2 + 31500000*p**3*q*r**2*s**2 + 12500000*q**3*r**2*s**2 + 35000000*p*q*r**3*s**2 + 1350000*p**6*s**3 + 6093750*p**3*q**2*s**3 + 17500000*q**4*s**3 - 7031250*p**4*r*s**3 - 127812500*p*q**2*r*s**3 + 18750000*p**2*r**2*s**3 - 162500000*r**3*s**3 + 107812500*p**2*q*s**4 + 460937500*q*r*s**4 - 214843750*p*s**5 a[2] = 1950*p**4*q**5 + 14100*p*q**7 - 14350*p**5*q**3*r - 125600*p**2*q**5*r + 27900*p**6*q*r**2 + 402250*p**3*q**3*r**2 + 288250*q**5*r**2 - 436000*p**4*q*r**3 - 1345000*p*q**3*r**3 + 1400000*p**2*q*r**4 + 9450*p**6*q**2*s - 1250*p**3*q**4*s - 465000*q**6*s - 49950*p**7*r*s - 302500*p**4*q**2*r*s + 1718750*p*q**4*r*s + 834000*p**5*r**2*s + 437500*p**2*q**2*r**2*s - 3100000*p**3*r**3*s - 1750000*q**2*r**3*s - 292500*p**5*q*s**2 - 1937500*p**2*q**3*s**2 + 3343750*p**3*q*r*s**2 + 1875000*q**3*r*s**2 + 8125000*p*q*r**2*s**2 - 1406250*p**4*s**3 - 12343750*p*q**2*s**3 + 5312500*p**2*r*s**3 - 43750000*r**2*s**3 + 74218750*q*s**4 a[1] = -300*p**5*q**3 - 2150*p**2*q**5 + 1350*p**6*q*r + 21500*p**3*q**3*r + 61500*q**5*r - 42000*p**4*q*r**2 - 290000*p*q**3*r**2 + 300000*p**2*q*r**3 - 4050*p**7*s - 45000*p**4*q**2*s - 125000*p*q**4*s + 108000*p**5*r*s + 643750*p**2*q**2*r*s - 700000*p**3*r**2*s - 375000*q**2*r**2*s - 93750*p**3*q*s**2 - 312500*q**3*s**2 + 1875000*p*q*r*s**2 - 1406250*p**2*s**3 - 9375000*r*s**3 a[0] = 1250*p**3*q**3 + 9000*q**5 - 4500*p**4*q*r - 46250*p*q**3*r + 50000*p**2*q*r**2 + 6750*p**5*s + 43750*p**2*q**2*s - 75000*p**3*r*s - 62500*q**2*r*s + 156250*p*q*s**2 - 1562500*s**3 return a @property def c(self): p, q, r, s = self.p, self.q, self.r, self.s c = [0]*6 c[5] = -40*p**5*q**11 - 270*p**2*q**13 + 700*p**6*q**9*r + 5165*p**3*q**11*r + 540*q**13*r - 4230*p**7*q**7*r**2 - 31845*p**4*q**9*r**2 + 20880*p*q**11*r**2 + 9645*p**8*q**5*r**3 + 57615*p**5*q**7*r**3 - 358255*p**2*q**9*r**3 - 1880*p**9*q**3*r**4 + 114020*p**6*q**5*r**4 + 2012190*p**3*q**7*r**4 - 26855*q**9*r**4 - 14400*p**10*q*r**5 - 470400*p**7*q**3*r**5 - 5088640*p**4*q**5*r**5 + 920*p*q**7*r**5 + 332800*p**8*q*r**6 + 5797120*p**5*q**3*r**6 + 1608000*p**2*q**5*r**6 - 2611200*p**6*q*r**7 - 7424000*p**3*q**3*r**7 - 2323200*q**5*r**7 + 8601600*p**4*q*r**8 + 9472000*p*q**3*r**8 - 10240000*p**2*q*r**9 - 3060*p**7*q**8*s - 39085*p**4*q**10*s - 132300*p*q**12*s + 36580*p**8*q**6*r*s + 520185*p**5*q**8*r*s + 1969860*p**2*q**10*r*s - 144045*p**9*q**4*r**2*s - 2438425*p**6*q**6*r**2*s - 10809475*p**3*q**8*r**2*s + 518850*q**10*r**2*s + 182520*p**10*q**2*r**3*s + 4533930*p**7*q**4*r**3*s + 26196770*p**4*q**6*r**3*s - 4542325*p*q**8*r**3*s + 21600*p**11*r**4*s - 2208080*p**8*q**2*r**4*s - 24787960*p**5*q**4*r**4*s + 10813900*p**2*q**6*r**4*s - 499200*p**9*r**5*s + 3827840*p**6*q**2*r**5*s + 9596000*p**3*q**4*r**5*s + 22662000*q**6*r**5*s + 3916800*p**7*r**6*s - 29952000*p**4*q**2*r**6*s - 90800000*p*q**4*r**6*s - 12902400*p**5*r**7*s + 87040000*p**2*q**2*r**7*s + 15360000*p**3*r**8*s + 12800000*q**2*r**8*s - 38070*p**9*q**5*s**2 - 566700*p**6*q**7*s**2 - 2574375*p**3*q**9*s**2 - 1822500*q**11*s**2 + 292815*p**10*q**3*r*s**2 + 5170280*p**7*q**5*r*s**2 + 27918125*p**4*q**7*r*s**2 + 21997500*p*q**9*r*s**2 - 573480*p**11*q*r**2*s**2 - 14566350*p**8*q**3*r**2*s**2 - 104851575*p**5*q**5*r**2*s**2 - 96448750*p**2*q**7*r**2*s**2 + 11001240*p**9*q*r**3*s**2 + 147798600*p**6*q**3*r**3*s**2 + 158632750*p**3*q**5*r**3*s**2 - 78222500*q**7*r**3*s**2 - 62819200*p**7*q*r**4*s**2 - 136160000*p**4*q**3*r**4*s**2 + 317555000*p*q**5*r**4*s**2 + 160224000*p**5*q*r**5*s**2 - 267600000*p**2*q**3*r**5*s**2 - 153600000*p**3*q*r**6*s**2 - 120000000*q**3*r**6*s**2 - 32000000*p*q*r**7*s**2 - 127575*p**11*q**2*s**3 - 2148750*p**8*q**4*s**3 - 13652500*p**5*q**6*s**3 - 19531250*p**2*q**8*s**3 + 495720*p**12*r*s**3 + 11856375*p**9*q**2*r*s**3 + 107807500*p**6*q**4*r*s**3 + 222334375*p**3*q**6*r*s**3 + 105062500*q**8*r*s**3 - 11566800*p**10*r**2*s**3 - 216787500*p**7*q**2*r**2*s**3 - 633437500*p**4*q**4*r**2*s**3 - 504484375*p*q**6*r**2*s**3 + 90918000*p**8*r**3*s**3 + 567080000*p**5*q**2*r**3*s**3 + 692937500*p**2*q**4*r**3*s**3 - 326640000*p**6*r**4*s**3 - 339000000*p**3*q**2*r**4*s**3 + 369250000*q**4*r**4*s**3 + 560000000*p**4*r**5*s**3 + 508000000*p*q**2*r**5*s**3 - 480000000*p**2*r**6*s**3 + 320000000*r**7*s**3 - 455625*p**10*q*s**4 - 27562500*p**7*q**3*s**4 - 120593750*p**4*q**5*s**4 - 60312500*p*q**7*s**4 + 110615625*p**8*q*r*s**4 + 662984375*p**5*q**3*r*s**4 + 528515625*p**2*q**5*r*s**4 - 541687500*p**6*q*r**2*s**4 - 1262343750*p**3*q**3*r**2*s**4 - 466406250*q**5*r**2*s**4 + 633000000*p**4*q*r**3*s**4 - 1264375000*p*q**3*r**3*s**4 + 1085000000*p**2*q*r**4*s**4 - 2700000000*q*r**5*s**4 - 68343750*p**9*s**5 - 478828125*p**6*q**2*s**5 - 355468750*p**3*q**4*s**5 - 11718750*q**6*s**5 + 718031250*p**7*r*s**5 + 1658593750*p**4*q**2*r*s**5 + 2212890625*p*q**4*r*s**5 - 2855625000*p**5*r**2*s**5 - 4273437500*p**2*q**2*r**2*s**5 + 4537500000*p**3*r**3*s**5 + 8031250000*q**2*r**3*s**5 - 1750000000*p*r**4*s**5 + 1353515625*p**5*q*s**6 + 1562500000*p**2*q**3*s**6 - 3964843750*p**3*q*r*s**6 - 7226562500*q**3*r*s**6 + 1953125000*p*q*r**2*s**6 - 1757812500*p**4*s**7 - 3173828125*p*q**2*s**7 + 6445312500*p**2*r*s**7 - 3906250000*r**2*s**7 + 6103515625*q*s**8 c[4] = 40*p**6*q**9 + 110*p**3*q**11 - 1080*q**13 - 560*p**7*q**7*r - 1780*p**4*q**9*r + 17370*p*q**11*r + 2850*p**8*q**5*r**2 + 10520*p**5*q**7*r**2 - 115910*p**2*q**9*r**2 - 6090*p**9*q**3*r**3 - 25330*p**6*q**5*r**3 + 448740*p**3*q**7*r**3 + 128230*q**9*r**3 + 4320*p**10*q*r**4 + 16960*p**7*q**3*r**4 - 1143600*p**4*q**5*r**4 - 1410310*p*q**7*r**4 + 3840*p**8*q*r**5 + 1744480*p**5*q**3*r**5 + 5619520*p**2*q**5*r**5 - 1198080*p**6*q*r**6 - 10579200*p**3*q**3*r**6 - 2940800*q**5*r**6 + 8294400*p**4*q*r**7 + 13568000*p*q**3*r**7 - 15360000*p**2*q*r**8 + 840*p**8*q**6*s + 7580*p**5*q**8*s + 24420*p**2*q**10*s - 8100*p**9*q**4*r*s - 94100*p**6*q**6*r*s - 473000*p**3*q**8*r*s - 473400*q**10*r*s + 22680*p**10*q**2*r**2*s + 374370*p**7*q**4*r**2*s + 2888020*p**4*q**6*r**2*s + 5561050*p*q**8*r**2*s - 12960*p**11*r**3*s - 485820*p**8*q**2*r**3*s - 6723440*p**5*q**4*r**3*s - 23561400*p**2*q**6*r**3*s + 190080*p**9*r**4*s + 5894880*p**6*q**2*r**4*s + 50882000*p**3*q**4*r**4*s + 22411500*q**6*r**4*s - 258560*p**7*r**5*s - 46248000*p**4*q**2*r**5*s - 103800000*p*q**4*r**5*s - 3737600*p**5*r**6*s + 119680000*p**2*q**2*r**6*s + 10240000*p**3*r**7*s + 19200000*q**2*r**7*s + 7290*p**10*q**3*s**2 + 117360*p**7*q**5*s**2 + 691250*p**4*q**7*s**2 - 198750*p*q**9*s**2 - 36450*p**11*q*r*s**2 - 854550*p**8*q**3*r*s**2 - 7340700*p**5*q**5*r*s**2 - 2028750*p**2*q**7*r*s**2 + 995490*p**9*q*r**2*s**2 + 18896600*p**6*q**3*r**2*s**2 + 5026500*p**3*q**5*r**2*s**2 - 52272500*q**7*r**2*s**2 - 16636800*p**7*q*r**3*s**2 - 43200000*p**4*q**3*r**3*s**2 + 223426250*p*q**5*r**3*s**2 + 112068000*p**5*q*r**4*s**2 - 177000000*p**2*q**3*r**4*s**2 - 244000000*p**3*q*r**5*s**2 - 156000000*q**3*r**5*s**2 + 43740*p**12*s**3 + 1032750*p**9*q**2*s**3 + 8602500*p**6*q**4*s**3 + 15606250*p**3*q**6*s**3 + 39625000*q**8*s**3 - 1603800*p**10*r*s**3 - 26932500*p**7*q**2*r*s**3 - 19562500*p**4*q**4*r*s**3 - 152000000*p*q**6*r*s**3 + 25555500*p**8*r**2*s**3 + 16230000*p**5*q**2*r**2*s**3 + 42187500*p**2*q**4*r**2*s**3 - 165660000*p**6*r**3*s**3 + 373500000*p**3*q**2*r**3*s**3 + 332937500*q**4*r**3*s**3 + 465000000*p**4*r**4*s**3 + 586000000*p*q**2*r**4*s**3 - 592000000*p**2*r**5*s**3 + 480000000*r**6*s**3 - 1518750*p**8*q*s**4 - 62531250*p**5*q**3*s**4 + 7656250*p**2*q**5*s**4 + 184781250*p**6*q*r*s**4 - 15781250*p**3*q**3*r*s**4 - 135156250*q**5*r*s**4 - 1148250000*p**4*q*r**2*s**4 - 2121406250*p*q**3*r**2*s**4 + 1990000000*p**2*q*r**3*s**4 - 3150000000*q*r**4*s**4 - 2531250*p**7*s**5 + 660937500*p**4*q**2*s**5 + 1339843750*p*q**4*s**5 - 33750000*p**5*r*s**5 - 679687500*p**2*q**2*r*s**5 + 6250000*p**3*r**2*s**5 + 6195312500*q**2*r**2*s**5 + 1125000000*p*r**3*s**5 - 996093750*p**3*q*s**6 - 3125000000*q**3*s**6 - 3222656250*p*q*r*s**6 + 1171875000*p**2*s**7 + 976562500*r*s**7 c[3] = 80*p**4*q**9 + 540*p*q**11 - 600*p**5*q**7*r - 4770*p**2*q**9*r + 1230*p**6*q**5*r**2 + 20900*p**3*q**7*r**2 + 47250*q**9*r**2 - 710*p**7*q**3*r**3 - 84950*p**4*q**5*r**3 - 526310*p*q**7*r**3 + 720*p**8*q*r**4 + 216280*p**5*q**3*r**4 + 2068020*p**2*q**5*r**4 - 198080*p**6*q*r**5 - 3703200*p**3*q**3*r**5 - 1423600*q**5*r**5 + 2860800*p**4*q*r**6 + 7056000*p*q**3*r**6 - 8320000*p**2*q*r**7 - 2720*p**6*q**6*s - 46350*p**3*q**8*s - 178200*q**10*s + 25740*p**7*q**4*r*s + 489490*p**4*q**6*r*s + 2152350*p*q**8*r*s - 61560*p**8*q**2*r**2*s - 1568150*p**5*q**4*r**2*s - 9060500*p**2*q**6*r**2*s + 24840*p**9*r**3*s + 1692380*p**6*q**2*r**3*s + 18098250*p**3*q**4*r**3*s + 9387750*q**6*r**3*s - 382560*p**7*r**4*s - 16818000*p**4*q**2*r**4*s - 49325000*p*q**4*r**4*s + 1212800*p**5*r**5*s + 64840000*p**2*q**2*r**5*s - 320000*p**3*r**6*s + 10400000*q**2*r**6*s - 36450*p**8*q**3*s**2 - 588350*p**5*q**5*s**2 - 2156250*p**2*q**7*s**2 + 123930*p**9*q*r*s**2 + 2879700*p**6*q**3*r*s**2 + 12548000*p**3*q**5*r*s**2 - 14445000*q**7*r*s**2 - 3233250*p**7*q*r**2*s**2 - 28485000*p**4*q**3*r**2*s**2 + 72231250*p*q**5*r**2*s**2 + 32093000*p**5*q*r**3*s**2 - 61275000*p**2*q**3*r**3*s**2 - 107500000*p**3*q*r**4*s**2 - 78500000*q**3*r**4*s**2 + 22000000*p*q*r**5*s**2 - 72900*p**10*s**3 - 1215000*p**7*q**2*s**3 - 2937500*p**4*q**4*s**3 + 9156250*p*q**6*s**3 + 2612250*p**8*r*s**3 + 16560000*p**5*q**2*r*s**3 - 75468750*p**2*q**4*r*s**3 - 32737500*p**6*r**2*s**3 + 169062500*p**3*q**2*r**2*s**3 + 121718750*q**4*r**2*s**3 + 160250000*p**4*r**3*s**3 + 219750000*p*q**2*r**3*s**3 - 317000000*p**2*r**4*s**3 + 260000000*r**5*s**3 + 2531250*p**6*q*s**4 + 22500000*p**3*q**3*s**4 + 39843750*q**5*s**4 - 266343750*p**4*q*r*s**4 - 776406250*p*q**3*r*s**4 + 789062500*p**2*q*r**2*s**4 - 1368750000*q*r**3*s**4 + 67500000*p**5*s**5 + 441406250*p**2*q**2*s**5 - 311718750*p**3*r*s**5 + 1785156250*q**2*r*s**5 + 546875000*p*r**2*s**5 - 1269531250*p*q*s**6 + 488281250*s**7 c[2] = 120*p**5*q**7 + 810*p**2*q**9 - 1280*p**6*q**5*r - 9160*p**3*q**7*r + 3780*q**9*r + 4530*p**7*q**3*r**2 + 36640*p**4*q**5*r**2 - 45270*p*q**7*r**2 - 5400*p**8*q*r**3 - 60920*p**5*q**3*r**3 + 200050*p**2*q**5*r**3 + 31200*p**6*q*r**4 - 476000*p**3*q**3*r**4 - 378200*q**5*r**4 + 521600*p**4*q*r**5 + 1872000*p*q**3*r**5 - 2240000*p**2*q*r**6 + 1440*p**7*q**4*s + 15310*p**4*q**6*s + 59400*p*q**8*s - 9180*p**8*q**2*r*s - 115240*p**5*q**4*r*s - 589650*p**2*q**6*r*s + 16200*p**9*r**2*s + 316710*p**6*q**2*r**2*s + 2547750*p**3*q**4*r**2*s + 2178000*q**6*r**2*s - 259200*p**7*r**3*s - 4123000*p**4*q**2*r**3*s - 11700000*p*q**4*r**3*s + 937600*p**5*r**4*s + 16340000*p**2*q**2*r**4*s - 640000*p**3*r**5*s + 2800000*q**2*r**5*s - 2430*p**9*q*s**2 - 54450*p**6*q**3*s**2 - 285500*p**3*q**5*s**2 - 2767500*q**7*s**2 + 43200*p**7*q*r*s**2 - 916250*p**4*q**3*r*s**2 + 14482500*p*q**5*r*s**2 + 4806000*p**5*q*r**2*s**2 - 13212500*p**2*q**3*r**2*s**2 - 25400000*p**3*q*r**3*s**2 - 18750000*q**3*r**3*s**2 + 8000000*p*q*r**4*s**2 + 121500*p**8*s**3 + 2058750*p**5*q**2*s**3 - 6656250*p**2*q**4*s**3 - 6716250*p**6*r*s**3 + 24125000*p**3*q**2*r*s**3 + 23875000*q**4*r*s**3 + 43125000*p**4*r**2*s**3 + 45750000*p*q**2*r**2*s**3 - 87500000*p**2*r**3*s**3 + 70000000*r**4*s**3 - 44437500*p**4*q*s**4 - 107968750*p*q**3*s**4 + 159531250*p**2*q*r*s**4 - 284375000*q*r**2*s**4 + 7031250*p**3*s**5 + 265625000*q**2*s**5 + 31250000*p*r*s**5 c[1] = 160*p**3*q**7 + 1080*q**9 - 1080*p**4*q**5*r - 8730*p*q**7*r + 1510*p**5*q**3*r**2 + 20420*p**2*q**5*r**2 + 720*p**6*q*r**3 - 23200*p**3*q**3*r**3 - 79900*q**5*r**3 + 35200*p**4*q*r**4 + 404000*p*q**3*r**4 - 480000*p**2*q*r**5 + 960*p**5*q**4*s + 2850*p**2*q**6*s + 540*p**6*q**2*r*s + 63500*p**3*q**4*r*s + 319500*q**6*r*s - 7560*p**7*r**2*s - 253500*p**4*q**2*r**2*s - 1806250*p*q**4*r**2*s + 91200*p**5*r**3*s + 2600000*p**2*q**2*r**3*s - 80000*p**3*r**4*s + 600000*q**2*r**4*s - 4050*p**7*q*s**2 - 120000*p**4*q**3*s**2 - 273750*p*q**5*s**2 + 425250*p**5*q*r*s**2 + 2325000*p**2*q**3*r*s**2 - 5400000*p**3*q*r**2*s**2 - 2875000*q**3*r**2*s**2 + 1500000*p*q*r**3*s**2 - 303750*p**6*s**3 - 843750*p**3*q**2*s**3 - 812500*q**4*s**3 + 5062500*p**4*r*s**3 + 13312500*p*q**2*r*s**3 - 14500000*p**2*r**2*s**3 + 15000000*r**3*s**3 - 3750000*p**2*q*s**4 - 35937500*q*r*s**4 + 11718750*p*s**5 c[0] = 80*p**4*q**5 + 540*p*q**7 - 600*p**5*q**3*r - 4770*p**2*q**5*r + 1080*p**6*q*r**2 + 11200*p**3*q**3*r**2 - 12150*q**5*r**2 - 4800*p**4*q*r**3 + 64000*p*q**3*r**3 - 80000*p**2*q*r**4 + 1080*p**6*q**2*s + 13250*p**3*q**4*s + 54000*q**6*s - 3240*p**7*r*s - 56250*p**4*q**2*r*s - 337500*p*q**4*r*s + 43200*p**5*r**2*s + 560000*p**2*q**2*r**2*s - 80000*p**3*r**3*s + 100000*q**2*r**3*s + 6750*p**5*q*s**2 + 225000*p**2*q**3*s**2 - 900000*p**3*q*r*s**2 - 562500*q**3*r*s**2 + 500000*p*q*r**2*s**2 + 843750*p**4*s**3 + 1937500*p*q**2*s**3 - 3000000*p**2*r*s**3 + 2500000*r**2*s**3 - 5468750*q*s**4 return c @property def F(self): p, q, r, s = self.p, self.q, self.r, self.s F = 4*p**6*q**6 + 59*p**3*q**8 + 216*q**10 - 36*p**7*q**4*r - 623*p**4*q**6*r - 2610*p*q**8*r + 81*p**8*q**2*r**2 + 2015*p**5*q**4*r**2 + 10825*p**2*q**6*r**2 - 1800*p**6*q**2*r**3 - 17500*p**3*q**4*r**3 + 625*q**6*r**3 + 10000*p**4*q**2*r**4 + 108*p**8*q**3*s + 1584*p**5*q**5*s + 5700*p**2*q**7*s - 486*p**9*q*r*s - 9720*p**6*q**3*r*s - 45050*p**3*q**5*r*s - 9000*q**7*r*s + 10800*p**7*q*r**2*s + 92500*p**4*q**3*r**2*s + 32500*p*q**5*r**2*s - 60000*p**5*q*r**3*s - 50000*p**2*q**3*r**3*s + 729*p**10*s**2 + 12150*p**7*q**2*s**2 + 60000*p**4*q**4*s**2 + 93750*p*q**6*s**2 - 18225*p**8*r*s**2 - 175500*p**5*q**2*r*s**2 - 478125*p**2*q**4*r*s**2 + 135000*p**6*r**2*s**2 + 850000*p**3*q**2*r**2*s**2 + 15625*q**4*r**2*s**2 - 250000*p**4*r**3*s**2 + 225000*p**3*q**3*s**3 + 175000*q**5*s**3 - 1012500*p**4*q*r*s**3 - 1187500*p*q**3*r*s**3 + 1250000*p**2*q*r**2*s**3 + 928125*p**5*s**4 + 1875000*p**2*q**2*s**4 - 2812500*p**3*r*s**4 - 390625*q**2*r*s**4 - 9765625*s**6 return F def l0(self, theta): F = self.F a = self.a l0 = Poly(a, x).eval(theta)/F return l0 def T(self, theta, d): F = self.F T = [0]*5 b = self.b # Note that the order of sublists of the b's has been reversed compared to the paper T[1] = -Poly(b[1], x).eval(theta)/(2*F) T[2] = Poly(b[2], x).eval(theta)/(2*d*F) T[3] = Poly(b[3], x).eval(theta)/(2*F) T[4] = Poly(b[4], x).eval(theta)/(2*d*F) return T def order(self, theta, d): F = self.F o = self.o order = Poly(o, x).eval(theta)/(d*F) return N(order) def uv(self, theta, d): c = self.c u = S(-25*self.q/2) v = Poly(c, x).eval(theta)/(2*d*self.F) return N(u), N(v) @property def zeta(self): return [self.zeta1, self.zeta2, self.zeta3, self.zeta4]

760bf2545b5f156792d1b10aef5b5a85cc07e8157ec7ee212c09df493302cd15

"""Implementation of RootOf class and related tools. """ from __future__ import print_function, division from sympy.core import (S, Expr, Integer, Float, I, oo, Add, Lambda, symbols, sympify, Rational, Dummy) from sympy.core.cache import cacheit from sympy.core.compatibility import range, ordered from sympy.core.function import AppliedUndef from sympy.polys.domains import QQ from sympy.polys.polyerrors import ( MultivariatePolynomialError, GeneratorsNeeded, PolynomialError, DomainError) from sympy.polys.polyfuncs import symmetrize, viete from sympy.polys.polyroots import ( roots_linear, roots_quadratic, roots_binomial, preprocess_roots, roots) from sympy.polys.polytools import Poly, PurePoly, factor from sympy.polys.rationaltools import together from sympy.polys.rootisolation import ( dup_isolate_complex_roots_sqf, dup_isolate_real_roots_sqf) from sympy.utilities import lambdify, public, sift from mpmath import mpf, mpc, findroot, workprec from mpmath.libmp.libmpf import dps_to_prec, prec_to_dps __all__ = ['CRootOf'] class _pure_key_dict(object): """A minimal dictionary that makes sure that the key is a univariate PurePoly instance. Examples ======== Only the following actions are guaranteed: >>> from sympy.polys.rootoftools import _pure_key_dict >>> from sympy import S, PurePoly >>> from sympy.abc import x, y 1) creation >>> P = _pure_key_dict() 2) assignment for a PurePoly or univariate polynomial >>> P[x] = 1 >>> P[PurePoly(x - y, x)] = 2 3) retrieval based on PurePoly key comparison (use this instead of the get method) >>> P[y] 1 4) KeyError when trying to retrieve a nonexisting key >>> P[y + 1] Traceback (most recent call last): ... KeyError: PurePoly(y + 1, y, domain='ZZ') 5) ability to query with ``in`` >>> x + 1 in P False NOTE: this is a *not* a dictionary. It is a very basic object for internal use that makes sure to always address its cache via PurePoly instances. It does not, for example, implement ``get`` or ``setdefault``. """ def __init__(self): self._dict = {} def __getitem__(self, k): if not isinstance(k, PurePoly): if not (isinstance(k, Expr) and len(k.free_symbols) == 1): raise KeyError k = PurePoly(k, expand=False) return self._dict[k] def __setitem__(self, k, v): if not isinstance(k, PurePoly): if not (isinstance(k, Expr) and len(k.free_symbols) == 1): raise ValueError('expecting univariate expression') k = PurePoly(k, expand=False) self._dict[k] = v def __contains__(self, k): try: self[k] return True except KeyError: return False _reals_cache = _pure_key_dict() _complexes_cache = _pure_key_dict() def _pure_factors(poly): _, factors = poly.factor_list() return [(PurePoly(f, expand=False), m) for f, m in factors] def _imag_count_of_factor(f): """Return the number of imaginary roots for irreducible univariate polynomial ``f``. """ terms = [(i, j) for (i,), j in f.terms()] if any(i % 2 for i, j in terms): return 0 # update signs even = [(i, I**i*j) for i, j in terms] even = Poly.from_dict(dict(even), Dummy('x')) return int(even.count_roots(-oo, oo)) @public def rootof(f, x, index=None, radicals=True, expand=True): """An indexed root of a univariate polynomial. Returns either a ``ComplexRootOf`` object or an explicit expression involving radicals. Parameters ========== f : Expr Univariate polynomial. x : Symbol, optional Generator for ``f``. index : int or Integer radicals : bool Return a radical expression if possible. expand : bool Expand ``f``. """ return CRootOf(f, x, index=index, radicals=radicals, expand=expand) @public class RootOf(Expr): """Represents a root of a univariate polynomial. Base class for roots of different kinds of polynomials. Only complex roots are currently supported. """ __slots__ = ['poly'] def __new__(cls, f, x, index=None, radicals=True, expand=True): """Construct a new ``CRootOf`` object for ``k``-th root of ``f``.""" return rootof(f, x, index=index, radicals=radicals, expand=expand) @public class ComplexRootOf(RootOf): """Represents an indexed complex root of a polynomial. Roots of a univariate polynomial separated into disjoint real or complex intervals and indexed in a fixed order. Currently only rational coefficients are allowed. Can be imported as ``CRootOf``. To avoid confusion, the generator must be a Symbol. Examples ======== >>> from sympy import CRootOf, rootof >>> from sympy.abc import x CRootOf is a way to reference a particular root of a polynomial. If there is a rational root, it will be returned: >>> CRootOf.clear_cache() # for doctest reproducibility >>> CRootOf(x**2 - 4, 0) -2 Whether roots involving radicals are returned or not depends on whether the ``radicals`` flag is true (which is set to True with rootof): >>> CRootOf(x**2 - 3, 0) CRootOf(x**2 - 3, 0) >>> CRootOf(x**2 - 3, 0, radicals=True) -sqrt(3) >>> rootof(x**2 - 3, 0) -sqrt(3) The following cannot be expressed in terms of radicals: >>> r = rootof(4*x**5 + 16*x**3 + 12*x**2 + 7, 0); r CRootOf(4*x**5 + 16*x**3 + 12*x**2 + 7, 0) The root bounds can be seen, however, and they are used by the evaluation methods to get numerical approximations for the root. >>> interval = r._get_interval(); interval (-1, 0) >>> r.evalf(2) -0.98 The evalf method refines the width of the root bounds until it guarantees that any decimal approximation within those bounds will satisfy the desired precision. It then stores the refined interval so subsequent requests at or below the requested precision will not have to recompute the root bounds and will return very quickly. Before evaluation above, the interval was >>> interval (-1, 0) After evaluation it is now >>. r._get_interval() (-165/169, -206/211) To reset all intervals for a given polynomial, the `_reset` method can be called from any CRootOf instance of the polynomial: >>> r._reset() >>> r._get_interval() (-1, 0) The `eval_approx` method will also find the root to a given precision but the interval is not modified unless the search for the root fails to converge within the root bounds. And the secant method is used to find the root. (The ``evalf`` method uses bisection and will always update the interval.) >>> r.eval_approx(2) -0.98 The interval needed to be slightly updated to find that root: >>> r._get_interval() (-1, -1/2) The ``evalf_rational`` will compute a rational approximation of the root to the desired accuracy or precision. >>> r.eval_rational(n=2) -69629/71318 >>> t = CRootOf(x**3 + 10*x + 1, 1) >>> t.eval_rational(1e-1) 15/256 - 805*I/256 >>> t.eval_rational(1e-1, 1e-4) 3275/65536 - 414645*I/131072 >>> t.eval_rational(1e-4, 1e-4) 6545/131072 - 414645*I/131072 >>> t.eval_rational(n=2) 104755/2097152 - 6634255*I/2097152 Notes ===== Although a PurePoly can be constructed from a non-symbol generator RootOf instances of non-symbols are disallowed to avoid confusion over what root is being represented. >>> from sympy import exp, PurePoly >>> PurePoly(x) == PurePoly(exp(x)) True >>> CRootOf(x - 1, 0) 1 >>> CRootOf(exp(x) - 1, 0) # would correspond to x == 0 Traceback (most recent call last): ... sympy.polys.polyerrors.PolynomialError: generator must be a Symbol See Also ======== eval_approx eval_rational _eval_evalf """ __slots__ = ['index'] is_complex = True is_number = True def __new__(cls, f, x, index=None, radicals=False, expand=True): """ Construct an indexed complex root of a polynomial. See ``rootof`` for the parameters. The default value of ``radicals`` is ``False`` to satisfy ``eval(srepr(expr) == expr``. """ x = sympify(x) if index is None and x.is_Integer: x, index = None, x else: index = sympify(index) if index is not None and index.is_Integer: index = int(index) else: raise ValueError("expected an integer root index, got %s" % index) poly = PurePoly(f, x, greedy=False, expand=expand) if not poly.is_univariate: raise PolynomialError("only univariate polynomials are allowed") if not poly.gen.is_Symbol: # PurePoly(sin(x) + 1) == PurePoly(x + 1) but the roots of # x for each are not the same: issue 8617 raise PolynomialError("generator must be a Symbol") degree = poly.degree() if degree <= 0: raise PolynomialError("can't construct CRootOf object for %s" % f) if index < -degree or index >= degree: raise IndexError("root index out of [%d, %d] range, got %d" % (-degree, degree - 1, index)) elif index < 0: index += degree dom = poly.get_domain() if not dom.is_Exact: poly = poly.to_exact() roots = cls._roots_trivial(poly, radicals) if roots is not None: return roots[index] coeff, poly = preprocess_roots(poly) dom = poly.get_domain() if not dom.is_ZZ: raise NotImplementedError("CRootOf is not supported over %s" % dom) root = cls._indexed_root(poly, index) return coeff * cls._postprocess_root(root, radicals) @classmethod def _new(cls, poly, index): """Construct new ``CRootOf`` object from raw data. """ obj = Expr.__new__(cls) obj.poly = PurePoly(poly) obj.index = index try: _reals_cache[obj.poly] = _reals_cache[poly] _complexes_cache[obj.poly] = _complexes_cache[poly] except KeyError: pass return obj def _hashable_content(self): return (self.poly, self.index) @property def expr(self): return self.poly.as_expr() @property def args(self): return (self.expr, Integer(self.index)) @property def free_symbols(self): # CRootOf currently only works with univariate expressions # whose poly attribute should be a PurePoly with no free # symbols return set() def _eval_is_real(self): """Return ``True`` if the root is real. """ return self.index < len(_reals_cache[self.poly]) def _eval_is_imaginary(self): """Return ``True`` if the root is imaginary. """ if self.index >= len(_reals_cache[self.poly]): ivl = self._get_interval() return ivl.ax*ivl.bx <= 0 # all others are on one side or the other return False # XXX is this necessary? @classmethod def real_roots(cls, poly, radicals=True): """Get real roots of a polynomial. """ return cls._get_roots("_real_roots", poly, radicals) @classmethod def all_roots(cls, poly, radicals=True): """Get real and complex roots of a polynomial. """ return cls._get_roots("_all_roots", poly, radicals) @classmethod def _get_reals_sqf(cls, currentfactor, use_cache=True): """Get real root isolating intervals for a square-free factor.""" if use_cache and currentfactor in _reals_cache: real_part = _reals_cache[currentfactor] else: _reals_cache[currentfactor] = real_part = \ dup_isolate_real_roots_sqf( currentfactor.rep.rep, currentfactor.rep.dom, blackbox=True) return real_part @classmethod def _get_complexes_sqf(cls, currentfactor, use_cache=True): """Get complex root isolating intervals for a square-free factor.""" if use_cache and currentfactor in _complexes_cache: complex_part = _complexes_cache[currentfactor] else: _complexes_cache[currentfactor] = complex_part = \ dup_isolate_complex_roots_sqf( currentfactor.rep.rep, currentfactor.rep.dom, blackbox=True) return complex_part @classmethod def _get_reals(cls, factors, use_cache=True): """Compute real root isolating intervals for a list of factors. """ reals = [] for currentfactor, k in factors: try: if not use_cache: raise KeyError r = _reals_cache[currentfactor] reals.extend([(i, currentfactor, k) for i in r]) except KeyError: real_part = cls._get_reals_sqf(currentfactor, use_cache) new = [(root, currentfactor, k) for root in real_part] reals.extend(new) reals = cls._reals_sorted(reals) return reals @classmethod def _get_complexes(cls, factors, use_cache=True): """Compute complex root isolating intervals for a list of factors. """ complexes = [] for currentfactor, k in ordered(factors): try: if not use_cache: raise KeyError c = _complexes_cache[currentfactor] complexes.extend([(i, currentfactor, k) for i in c]) except KeyError: complex_part = cls._get_complexes_sqf(currentfactor, use_cache) new = [(root, currentfactor, k) for root in complex_part] complexes.extend(new) complexes = cls._complexes_sorted(complexes) return complexes @classmethod def _reals_sorted(cls, reals): """Make real isolating intervals disjoint and sort roots. """ cache = {} for i, (u, f, k) in enumerate(reals): for j, (v, g, m) in enumerate(reals[i + 1:]): u, v = u.refine_disjoint(v) reals[i + j + 1] = (v, g, m) reals[i] = (u, f, k) reals = sorted(reals, key=lambda r: r[0].a) for root, currentfactor, _ in reals: if currentfactor in cache: cache[currentfactor].append(root) else: cache[currentfactor] = [root] for currentfactor, root in cache.items(): _reals_cache[currentfactor] = root return reals @classmethod def _refine_imaginary(cls, complexes): sifted = sift(complexes, lambda c: c[1]) complexes = [] for f in ordered(sifted): nimag = _imag_count_of_factor(f) if nimag == 0: # refine until xbounds are neg or pos for u, f, k in sifted[f]: while u.ax*u.bx <= 0: u = u._inner_refine() complexes.append((u, f, k)) else: # refine until all but nimag xbounds are neg or pos potential_imag = list(range(len(sifted[f]))) while True: assert len(potential_imag) > 1 for i in list(potential_imag): u, f, k = sifted[f][i] if u.ax*u.bx > 0: potential_imag.remove(i) elif u.ax != u.bx: u = u._inner_refine() sifted[f][i] = u, f, k if len(potential_imag) == nimag: break complexes.extend(sifted[f]) return complexes @classmethod def _refine_complexes(cls, complexes): """return complexes such that no bounding rectangles of non-conjugate roots would intersect. In addition, assure that neither ay nor by is 0 to guarantee that non-real roots are distinct from real roots in terms of the y-bounds. """ # get the intervals pairwise-disjoint. # If rectangles were drawn around the coordinates of the bounding # rectangles, no rectangles would intersect after this procedure. for i, (u, f, k) in enumerate(complexes): for j, (v, g, m) in enumerate(complexes[i + 1:]): u, v = u.refine_disjoint(v) complexes[i + j + 1] = (v, g, m) complexes[i] = (u, f, k) # refine until the x-bounds are unambiguously positive or negative # for non-imaginary roots complexes = cls._refine_imaginary(complexes) # make sure that all y bounds are off the real axis # and on the same side of the axis for i, (u, f, k) in enumerate(complexes): while u.ay*u.by <= 0: u = u.refine() complexes[i] = u, f, k return complexes @classmethod def _complexes_sorted(cls, complexes): """Make complex isolating intervals disjoint and sort roots. """ complexes = cls._refine_complexes(complexes) # XXX don't sort until you are sure that it is compatible # with the indexing method but assert that the desired state # is not broken C, F = 0, 1 # location of ComplexInterval and factor fs = set([i[F] for i in complexes]) for i in range(1, len(complexes)): if complexes[i][F] != complexes[i - 1][F]: # if this fails the factors of a root were not # contiguous because a discontinuity should only # happen once fs.remove(complexes[i - 1][F]) for i in range(len(complexes)): # negative im part (conj=True) comes before # positive im part (conj=False) assert complexes[i][C].conj is (i % 2 == 0) # update cache cache = {} # -- collate for root, currentfactor, _ in complexes: cache.setdefault(currentfactor, []).append(root) # -- store for currentfactor, root in cache.items(): _complexes_cache[currentfactor] = root return complexes @classmethod def _reals_index(cls, reals, index): """ Map initial real root index to an index in a factor where the root belongs. """ i = 0 for j, (_, currentfactor, k) in enumerate(reals): if index < i + k: poly, index = currentfactor, 0 for _, currentfactor, _ in reals[:j]: if currentfactor == poly: index += 1 return poly, index else: i += k @classmethod def _complexes_index(cls, complexes, index): """ Map initial complex root index to an index in a factor where the root belongs. """ i = 0 for j, (_, currentfactor, k) in enumerate(complexes): if index < i + k: poly, index = currentfactor, 0 for _, currentfactor, _ in complexes[:j]: if currentfactor == poly: index += 1 index += len(_reals_cache[poly]) return poly, index else: i += k @classmethod def _count_roots(cls, roots): """Count the number of real or complex roots with multiplicities.""" return sum([k for _, _, k in roots]) @classmethod def _indexed_root(cls, poly, index): """Get a root of a composite polynomial by index. """ factors = _pure_factors(poly) reals = cls._get_reals(factors) reals_count = cls._count_roots(reals) if index < reals_count: return cls._reals_index(reals, index) else: complexes = cls._get_complexes(factors) return cls._complexes_index(complexes, index - reals_count) @classmethod def _real_roots(cls, poly): """Get real roots of a composite polynomial. """ factors = _pure_factors(poly) reals = cls._get_reals(factors) reals_count = cls._count_roots(reals) roots = [] for index in range(0, reals_count): roots.append(cls._reals_index(reals, index)) return roots def _reset(self): self._all_roots(self.poly, use_cache=False) @classmethod def _all_roots(cls, poly, use_cache=True): """Get real and complex roots of a composite polynomial. """ factors = _pure_factors(poly) reals = cls._get_reals(factors, use_cache=use_cache) reals_count = cls._count_roots(reals) roots = [] for index in range(0, reals_count): roots.append(cls._reals_index(reals, index)) complexes = cls._get_complexes(factors, use_cache=use_cache) complexes_count = cls._count_roots(complexes) for index in range(0, complexes_count): roots.append(cls._complexes_index(complexes, index)) return roots @classmethod @cacheit def _roots_trivial(cls, poly, radicals): """Compute roots in linear, quadratic and binomial cases. """ if poly.degree() == 1: return roots_linear(poly) if not radicals: return None if poly.degree() == 2: return roots_quadratic(poly) elif poly.length() == 2 and poly.TC(): return roots_binomial(poly) else: return None @classmethod def _preprocess_roots(cls, poly): """Take heroic measures to make ``poly`` compatible with ``CRootOf``.""" dom = poly.get_domain() if not dom.is_Exact: poly = poly.to_exact() coeff, poly = preprocess_roots(poly) dom = poly.get_domain() if not dom.is_ZZ: raise NotImplementedError( "sorted roots not supported over %s" % dom) return coeff, poly @classmethod def _postprocess_root(cls, root, radicals): """Return the root if it is trivial or a ``CRootOf`` object. """ poly, index = root roots = cls._roots_trivial(poly, radicals) if roots is not None: return roots[index] else: return cls._new(poly, index) @classmethod def _get_roots(cls, method, poly, radicals): """Return postprocessed roots of specified kind. """ if not poly.is_univariate: raise PolynomialError("only univariate polynomials are allowed") coeff, poly = cls._preprocess_roots(poly) roots = [] for root in getattr(cls, method)(poly): roots.append(coeff*cls._postprocess_root(root, radicals)) return roots @classmethod def clear_cache(cls): """Reset cache for reals and complexes. The intervals used to approximate a root instance are updated as needed. When a request is made to see the intervals, the most current values are shown. `clear_cache` will reset all CRootOf instances back to their original state. See Also ======== _reset """ global _reals_cache, _complexes_cache _reals_cache = _pure_key_dict() _complexes_cache = _pure_key_dict() def _get_interval(self): """Internal function for retrieving isolation interval from cache. """ if self.is_real: return _reals_cache[self.poly][self.index] else: reals_count = len(_reals_cache[self.poly]) return _complexes_cache[self.poly][self.index - reals_count] def _set_interval(self, interval): """Internal function for updating isolation interval in cache. """ if self.is_real: _reals_cache[self.poly][self.index] = interval else: reals_count = len(_reals_cache[self.poly]) _complexes_cache[self.poly][self.index - reals_count] = interval def _eval_subs(self, old, new): # don't allow subs to change anything return self def _eval_conjugate(self): if self.is_real: return self expr, i = self.args return self.func(expr, i + (1 if self._get_interval().conj else -1)) def eval_approx(self, n): """Evaluate this complex root to the given precision. This uses secant method and root bounds are used to both generate an initial guess and to check that the root returned is valid. If ever the method converges outside the root bounds, the bounds will be made smaller and updated. """ prec = dps_to_prec(n) with workprec(prec): g = self.poly.gen if not g.is_Symbol: d = Dummy('x') if self.is_imaginary: d *= I func = lambdify(d, self.expr.subs(g, d)) else: expr = self.expr if self.is_imaginary: expr = self.expr.subs(g, I*g) func = lambdify(g, expr) interval = self._get_interval() while True: if self.is_real: a = mpf(str(interval.a)) b = mpf(str(interval.b)) if a == b: root = a break x0 = mpf(str(interval.center)) x1 = x0 + mpf(str(interval.dx))/4 elif self.is_imaginary: a = mpf(str(interval.ay)) b = mpf(str(interval.by)) if a == b: root = mpc(mpf('0'), a) break x0 = mpf(str(interval.center[1])) x1 = x0 + mpf(str(interval.dy))/4 else: ax = mpf(str(interval.ax)) bx = mpf(str(interval.bx)) ay = mpf(str(interval.ay)) by = mpf(str(interval.by)) if ax == bx and ay == by: root = mpc(ax, ay) break x0 = mpc(*map(str, interval.center)) x1 = x0 + mpc(*map(str, (interval.dx, interval.dy)))/4 try: # without a tolerance, this will return when (to within # the given precision) x_i == x_{i-1} root = findroot(func, (x0, x1)) # If the (real or complex) root is not in the 'interval', # then keep refining the interval. This happens if findroot # accidentally finds a different root outside of this # interval because our initial estimate 'x0' was not close # enough. It is also possible that the secant method will # get trapped by a max/min in the interval; the root # verification by findroot will raise a ValueError in this # case and the interval will then be tightened -- and # eventually the root will be found. # # It is also possible that findroot will not have any # successful iterations to process (in which case it # will fail to initialize a variable that is tested # after the iterations and raise an UnboundLocalError). if self.is_real or self.is_imaginary: if not bool(root.imag) == self.is_real and ( a <= root <= b): if self.is_imaginary: root = mpc(mpf('0'), root.real) break elif (ax <= root.real <= bx and ay <= root.imag <= by): break except (UnboundLocalError, ValueError): pass interval = interval.refine() # update the interval so we at least (for this precision or # less) don't have much work to do to recompute the root self._set_interval(interval) return (Float._new(root.real._mpf_, prec) + I*Float._new(root.imag._mpf_, prec)) def _eval_evalf(self, prec, **kwargs): """Evaluate this complex root to the given precision.""" # all kwargs are ignored return self.eval_rational(n=prec_to_dps(prec))._evalf(prec) def eval_rational(self, dx=None, dy=None, n=15): """ Return a Rational approximation of ``self`` that has real and imaginary component approximations that are within ``dx`` and ``dy`` of the true values, respectively. Alternatively, ``n`` digits of precision can be specified. The interval is refined with bisection and is sure to converge. The root bounds are updated when the refinement is complete so recalculation at the same or lesser precision will not have to repeat the refinement and should be much faster. The following example first obtains Rational approximation to 1e-8 accuracy for all roots of the 4-th order Legendre polynomial. Since the roots are all less than 1, this will ensure the decimal representation of the approximation will be correct (including rounding) to 6 digits: >>> from sympy import S, legendre_poly, Symbol >>> x = Symbol("x") >>> p = legendre_poly(4, x, polys=True) >>> r = p.real_roots()[-1] >>> r.eval_rational(10**-8).n(6) 0.861136 It is not necessary to a two-step calculation, however: the decimal representation can be computed directly: >>> r.evalf(17) 0.86113631159405258 """ dy = dy or dx if dx: rtol = None dx = dx if isinstance(dx, Rational) else Rational(str(dx)) dy = dy if isinstance(dy, Rational) else Rational(str(dy)) else: # 5 binary (or 2 decimal) digits are needed to ensure that # a given digit is correctly rounded # prec_to_dps(dps_to_prec(n) + 5) - n <= 2 (tested for # n in range(1000000) rtol = S(10)**-(n + 2) # +2 for guard digits interval = self._get_interval() while True: if self.is_real: if rtol: dx = abs(interval.center*rtol) interval = interval.refine_size(dx=dx) c = interval.center real = Rational(c) imag = S.Zero if not rtol or interval.dx < abs(c*rtol): break elif self.is_imaginary: if rtol: dy = abs(interval.center[1]*rtol) dx = 1 interval = interval.refine_size(dx=dx, dy=dy) c = interval.center[1] imag = Rational(c) real = S.Zero if not rtol or interval.dy < abs(c*rtol): break else: if rtol: dx = abs(interval.center[0]*rtol) dy = abs(interval.center[1]*rtol) interval = interval.refine_size(dx, dy) c = interval.center real, imag = map(Rational, c) if not rtol or ( interval.dx < abs(c[0]*rtol) and interval.dy < abs(c[1]*rtol)): break # update the interval so we at least (for this precision or # less) don't have much work to do to recompute the root self._set_interval(interval) return real + I*imag def _eval_Eq(self, other): # CRootOf represents a Root, so if other is that root, it should set # the expression to zero *and* it should be in the interval of the # CRootOf instance. It must also be a number that agrees with the # is_real value of the CRootOf instance. if type(self) == type(other): return sympify(self == other) if not (other.is_number and not other.has(AppliedUndef)): return S.false if not other.is_finite: return S.false z = self.expr.subs(self.expr.free_symbols.pop(), other).is_zero if z is False: # all roots will make z True but we don't know # whether this is the right root if z is True return S.false o = other.is_real, other.is_imaginary s = self.is_real, self.is_imaginary assert None not in s # this is part of initial refinement if o != s and None not in o: return S.false re, im = other.as_real_imag() if self.is_real: if im: return S.false i = self._get_interval() a, b = [Rational(str(_)) for _ in (i.a, i.b)] return sympify(a <= other and other <= b) i = self._get_interval() r1, r2, i1, i2 = [Rational(str(j)) for j in ( i.ax, i.bx, i.ay, i.by)] return sympify(( r1 <= re and re <= r2) and ( i1 <= im and im <= i2)) CRootOf = ComplexRootOf @public class RootSum(Expr): """Represents a sum of all roots of a univariate polynomial. """ __slots__ = ['poly', 'fun', 'auto'] def __new__(cls, expr, func=None, x=None, auto=True, quadratic=False): """Construct a new ``RootSum`` instance of roots of a polynomial.""" coeff, poly = cls._transform(expr, x) if not poly.is_univariate: raise MultivariatePolynomialError( "only univariate polynomials are allowed") if func is None: func = Lambda(poly.gen, poly.gen) else: try: is_func = func.is_Function except AttributeError: is_func = False if is_func and 1 in func.nargs: if not isinstance(func, Lambda): func = Lambda(poly.gen, func(poly.gen)) else: raise ValueError( "expected a univariate function, got %s" % func) var, expr = func.variables[0], func.expr if coeff is not S.One: expr = expr.subs(var, coeff*var) deg = poly.degree() if not expr.has(var): return deg*expr if expr.is_Add: add_const, expr = expr.as_independent(var) else: add_const = S.Zero if expr.is_Mul: mul_const, expr = expr.as_independent(var) else: mul_const = S.One func = Lambda(var, expr) rational = cls._is_func_rational(poly, func) factors, terms = _pure_factors(poly), [] for poly, k in factors: if poly.is_linear: term = func(roots_linear(poly)[0]) elif quadratic and poly.is_quadratic: term = sum(map(func, roots_quadratic(poly))) else: if not rational or not auto: term = cls._new(poly, func, auto) else: term = cls._rational_case(poly, func) terms.append(k*term) return mul_const*Add(*terms) + deg*add_const @classmethod def _new(cls, poly, func, auto=True): """Construct new raw ``RootSum`` instance. """ obj = Expr.__new__(cls) obj.poly = poly obj.fun = func obj.auto = auto return obj @classmethod def new(cls, poly, func, auto=True): """Construct new ``RootSum`` instance. """ if not func.expr.has(*func.variables): return func.expr rational = cls._is_func_rational(poly, func) if not rational or not auto: return cls._new(poly, func, auto) else: return cls._rational_case(poly, func) @classmethod def _transform(cls, expr, x): """Transform an expression to a polynomial. """ poly = PurePoly(expr, x, greedy=False) return preprocess_roots(poly) @classmethod def _is_func_rational(cls, poly, func): """Check if a lambda is a rational function. """ var, expr = func.variables[0], func.expr return expr.is_rational_function(var) @classmethod def _rational_case(cls, poly, func): """Handle the rational function case. """ roots = symbols('r:%d' % poly.degree()) var, expr = func.variables[0], func.expr f = sum(expr.subs(var, r) for r in roots) p, q = together(f).as_numer_denom() domain = QQ[roots] p = p.expand() q = q.expand() try: p = Poly(p, domain=domain, expand=False) except GeneratorsNeeded: p, p_coeff = None, (p,) else: p_monom, p_coeff = zip(*p.terms()) try: q = Poly(q, domain=domain, expand=False) except GeneratorsNeeded: q, q_coeff = None, (q,) else: q_monom, q_coeff = zip(*q.terms()) coeffs, mapping = symmetrize(p_coeff + q_coeff, formal=True) formulas, values = viete(poly, roots), [] for (sym, _), (_, val) in zip(mapping, formulas): values.append((sym, val)) for i, (coeff, _) in enumerate(coeffs): coeffs[i] = coeff.subs(values) n = len(p_coeff) p_coeff = coeffs[:n] q_coeff = coeffs[n:] if p is not None: p = Poly(dict(zip(p_monom, p_coeff)), *p.gens).as_expr() else: (p,) = p_coeff if q is not None: q = Poly(dict(zip(q_monom, q_coeff)), *q.gens).as_expr() else: (q,) = q_coeff return factor(p/q) def _hashable_content(self): return (self.poly, self.fun) @property def expr(self): return self.poly.as_expr() @property def args(self): return (self.expr, self.fun, self.poly.gen) @property def free_symbols(self): return self.poly.free_symbols | self.fun.free_symbols @property def is_commutative(self): return True def doit(self, **hints): if not hints.get('roots', True): return self _roots = roots(self.poly, multiple=True) if len(_roots) < self.poly.degree(): return self else: return Add(*[self.fun(r) for r in _roots]) def _eval_evalf(self, prec): try: _roots = self.poly.nroots(n=prec_to_dps(prec)) except (DomainError, PolynomialError): return self else: return Add(*[self.fun(r) for r in _roots]) def _eval_derivative(self, x): var, expr = self.fun.args func = Lambda(var, expr.diff(x)) return self.new(self.poly, func, self.auto)

a4d17263800c1ea9f1d31a74cf7cfc8dd86fca967cefbd1505fb2cfee5242308

"""Square-free decomposition algorithms and related tools. """ from __future__ import print_function, division from sympy.polys.densearith import ( dup_neg, dmp_neg, dup_sub, dmp_sub, dup_mul, dup_quo, dmp_quo, dup_mul_ground, dmp_mul_ground) from sympy.polys.densebasic import ( dup_strip, dup_LC, dmp_ground_LC, dmp_zero_p, dmp_ground, dup_degree, dmp_degree, dmp_raise, dmp_inject, dup_convert) from sympy.polys.densetools import ( dup_diff, dmp_diff, dup_shift, dmp_compose, dup_monic, dmp_ground_monic, dup_primitive, dmp_ground_primitive) from sympy.polys.euclidtools import ( dup_inner_gcd, dmp_inner_gcd, dup_gcd, dmp_gcd, dmp_resultant) from sympy.polys.galoistools import ( gf_sqf_list, gf_sqf_part) from sympy.polys.polyerrors import ( MultivariatePolynomialError, DomainError) def dup_sqf_p(f, K): """ Return ``True`` if ``f`` is a square-free polynomial in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_sqf_p(x**2 - 2*x + 1) False >>> R.dup_sqf_p(x**2 - 1) True """ if not f: return True else: return not dup_degree(dup_gcd(f, dup_diff(f, 1, K), K)) def dmp_sqf_p(f, u, K): """ Return ``True`` if ``f`` is a square-free polynomial in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_sqf_p(x**2 + 2*x*y + y**2) False >>> R.dmp_sqf_p(x**2 + y**2) True """ if dmp_zero_p(f, u): return True else: return not dmp_degree(dmp_gcd(f, dmp_diff(f, 1, u, K), u, K), u) def dup_sqf_norm(f, K): """ Square-free norm of ``f`` in ``K[x]``, useful over algebraic domains. Returns ``s``, ``f``, ``r``, such that ``g(x) = f(x-sa)`` and ``r(x) = Norm(g(x))`` is a square-free polynomial over K, where ``a`` is the algebraic extension of ``K``. Examples ======== >>> from sympy.polys import ring, QQ >>> from sympy import sqrt >>> K = QQ.algebraic_field(sqrt(3)) >>> R, x = ring("x", K) >>> _, X = ring("x", QQ) >>> s, f, r = R.dup_sqf_norm(x**2 - 2) >>> s == 1 True >>> f == x**2 + K([QQ(-2), QQ(0)])*x + 1 True >>> r == X**4 - 10*X**2 + 1 True """ if not K.is_Algebraic: raise DomainError("ground domain must be algebraic") s, g = 0, dmp_raise(K.mod.rep, 1, 0, K.dom) while True: h, _ = dmp_inject(f, 0, K, front=True) r = dmp_resultant(g, h, 1, K.dom) if dup_sqf_p(r, K.dom): break else: f, s = dup_shift(f, -K.unit, K), s + 1 return s, f, r def dmp_sqf_norm(f, u, K): """ Square-free norm of ``f`` in ``K[X]``, useful over algebraic domains. Returns ``s``, ``f``, ``r``, such that ``g(x) = f(x-sa)`` and ``r(x) = Norm(g(x))`` is a square-free polynomial over K, where ``a`` is the algebraic extension of ``K``. Examples ======== >>> from sympy.polys import ring, QQ >>> from sympy import I >>> K = QQ.algebraic_field(I) >>> R, x, y = ring("x,y", K) >>> _, X, Y = ring("x,y", QQ) >>> s, f, r = R.dmp_sqf_norm(x*y + y**2) >>> s == 1 True >>> f == x*y + y**2 + K([QQ(-1), QQ(0)])*y True >>> r == X**2*Y**2 + 2*X*Y**3 + Y**4 + Y**2 True """ if not u: return dup_sqf_norm(f, K) if not K.is_Algebraic: raise DomainError("ground domain must be algebraic") g = dmp_raise(K.mod.rep, u + 1, 0, K.dom) F = dmp_raise([K.one, -K.unit], u, 0, K) s = 0 while True: h, _ = dmp_inject(f, u, K, front=True) r = dmp_resultant(g, h, u + 1, K.dom) if dmp_sqf_p(r, u, K.dom): break else: f, s = dmp_compose(f, F, u, K), s + 1 return s, f, r def dmp_norm(f, u, K): """ Norm of ``f`` in ``K[X1, ..., Xn]``, often not square-free. """ if not K.is_Algebraic: raise DomainError("ground domain must be algebraic") g = dmp_raise(K.mod.rep, u + 1, 0, K.dom) h, _ = dmp_inject(f, u, K, front=True) return dmp_resultant(g, h, u + 1, K.dom) def dup_gf_sqf_part(f, K): """Compute square-free part of ``f`` in ``GF(p)[x]``. """ f = dup_convert(f, K, K.dom) g = gf_sqf_part(f, K.mod, K.dom) return dup_convert(g, K.dom, K) def dmp_gf_sqf_part(f, K): """Compute square-free part of ``f`` in ``GF(p)[X]``. """ raise NotImplementedError('multivariate polynomials over finite fields') def dup_sqf_part(f, K): """ Returns square-free part of a polynomial in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_sqf_part(x**3 - 3*x - 2) x**2 - x - 2 """ if K.is_FiniteField: return dup_gf_sqf_part(f, K) if not f: return f if K.is_negative(dup_LC(f, K)): f = dup_neg(f, K) gcd = dup_gcd(f, dup_diff(f, 1, K), K) sqf = dup_quo(f, gcd, K) if K.is_Field: return dup_monic(sqf, K) else: return dup_primitive(sqf, K)[1] def dmp_sqf_part(f, u, K): """ Returns square-free part of a polynomial in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_sqf_part(x**3 + 2*x**2*y + x*y**2) x**2 + x*y """ if not u: return dup_sqf_part(f, K) if K.is_FiniteField: return dmp_gf_sqf_part(f, u, K) if dmp_zero_p(f, u): return f if K.is_negative(dmp_ground_LC(f, u, K)): f = dmp_neg(f, u, K) gcd = dmp_gcd(f, dmp_diff(f, 1, u, K), u, K) sqf = dmp_quo(f, gcd, u, K) if K.is_Field: return dmp_ground_monic(sqf, u, K) else: return dmp_ground_primitive(sqf, u, K)[1] def dup_gf_sqf_list(f, K, all=False): """Compute square-free decomposition of ``f`` in ``GF(p)[x]``. """ f = dup_convert(f, K, K.dom) coeff, factors = gf_sqf_list(f, K.mod, K.dom, all=all) for i, (f, k) in enumerate(factors): factors[i] = (dup_convert(f, K.dom, K), k) return K.convert(coeff, K.dom), factors def dmp_gf_sqf_list(f, u, K, all=False): """Compute square-free decomposition of ``f`` in ``GF(p)[X]``. """ raise NotImplementedError('multivariate polynomials over finite fields') def dup_sqf_list(f, K, all=False): """ Return square-free decomposition of a polynomial in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> f = 2*x**5 + 16*x**4 + 50*x**3 + 76*x**2 + 56*x + 16 >>> R.dup_sqf_list(f) (2, [(x + 1, 2), (x + 2, 3)]) >>> R.dup_sqf_list(f, all=True) (2, [(1, 1), (x + 1, 2), (x + 2, 3)]) """ if K.is_FiniteField: return dup_gf_sqf_list(f, K, all=all) if K.is_Field: coeff = dup_LC(f, K) f = dup_monic(f, K) else: coeff, f = dup_primitive(f, K) if K.is_negative(dup_LC(f, K)): f = dup_neg(f, K) coeff = -coeff if dup_degree(f) <= 0: return coeff, [] result, i = [], 1 h = dup_diff(f, 1, K) g, p, q = dup_inner_gcd(f, h, K) while True: d = dup_diff(p, 1, K) h = dup_sub(q, d, K) if not h: result.append((p, i)) break g, p, q = dup_inner_gcd(p, h, K) if all or dup_degree(g) > 0: result.append((g, i)) i += 1 return coeff, result def dup_sqf_list_include(f, K, all=False): """ Return square-free decomposition of a polynomial in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> f = 2*x**5 + 16*x**4 + 50*x**3 + 76*x**2 + 56*x + 16 >>> R.dup_sqf_list_include(f) [(2, 1), (x + 1, 2), (x + 2, 3)] >>> R.dup_sqf_list_include(f, all=True) [(2, 1), (x + 1, 2), (x + 2, 3)] """ coeff, factors = dup_sqf_list(f, K, all=all) if factors and factors[0][1] == 1: g = dup_mul_ground(factors[0][0], coeff, K) return [(g, 1)] + factors[1:] else: g = dup_strip([coeff]) return [(g, 1)] + factors def dmp_sqf_list(f, u, K, all=False): """ Return square-free decomposition of a polynomial in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = x**5 + 2*x**4*y + x**3*y**2 >>> R.dmp_sqf_list(f) (1, [(x + y, 2), (x, 3)]) >>> R.dmp_sqf_list(f, all=True) (1, [(1, 1), (x + y, 2), (x, 3)]) """ if not u: return dup_sqf_list(f, K, all=all) if K.is_FiniteField: return dmp_gf_sqf_list(f, u, K, all=all) if K.is_Field: coeff = dmp_ground_LC(f, u, K) f = dmp_ground_monic(f, u, K) else: coeff, f = dmp_ground_primitive(f, u, K) if K.is_negative(dmp_ground_LC(f, u, K)): f = dmp_neg(f, u, K) coeff = -coeff if dmp_degree(f, u) <= 0: return coeff, [] result, i = [], 1 h = dmp_diff(f, 1, u, K) g, p, q = dmp_inner_gcd(f, h, u, K) while True: d = dmp_diff(p, 1, u, K) h = dmp_sub(q, d, u, K) if dmp_zero_p(h, u): result.append((p, i)) break g, p, q = dmp_inner_gcd(p, h, u, K) if all or dmp_degree(g, u) > 0: result.append((g, i)) i += 1 return coeff, result def dmp_sqf_list_include(f, u, K, all=False): """ Return square-free decomposition of a polynomial in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = x**5 + 2*x**4*y + x**3*y**2 >>> R.dmp_sqf_list_include(f) [(1, 1), (x + y, 2), (x, 3)] >>> R.dmp_sqf_list_include(f, all=True) [(1, 1), (x + y, 2), (x, 3)] """ if not u: return dup_sqf_list_include(f, K, all=all) coeff, factors = dmp_sqf_list(f, u, K, all=all) if factors and factors[0][1] == 1: g = dmp_mul_ground(factors[0][0], coeff, u, K) return [(g, 1)] + factors[1:] else: g = dmp_ground(coeff, u) return [(g, 1)] + factors def dup_gff_list(f, K): """ Compute greatest factorial factorization of ``f`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_gff_list(x**5 + 2*x**4 - x**3 - 2*x**2) [(x, 1), (x + 2, 4)] """ if not f: raise ValueError("greatest factorial factorization doesn't exist for a zero polynomial") f = dup_monic(f, K) if not dup_degree(f): return [] else: g = dup_gcd(f, dup_shift(f, K.one, K), K) H = dup_gff_list(g, K) for i, (h, k) in enumerate(H): g = dup_mul(g, dup_shift(h, -K(k), K), K) H[i] = (h, k + 1) f = dup_quo(f, g, K) if not dup_degree(f): return H else: return [(f, 1)] + H def dmp_gff_list(f, u, K): """ Compute greatest factorial factorization of ``f`` in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) """ if not u: return dup_gff_list(f, K) else: raise MultivariatePolynomialError(f)

fc6c2ad1f01568a3a0ed6d376dffc083aae0f537b20a92c70fabc6e50dc4edd3

"""Advanced tools for dense recursive polynomials in ``K[x]`` or ``K[X]``. """ from __future__ import print_function, division from sympy.core.compatibility import range from sympy.polys.densearith import ( dup_add_term, dmp_add_term, dup_lshift, dup_add, dmp_add, dup_sub, dmp_sub, dup_mul, dmp_mul, dup_sqr, dup_div, dup_rem, dmp_rem, dmp_expand, dup_mul_ground, dmp_mul_ground, dup_quo_ground, dmp_quo_ground, dup_exquo_ground, dmp_exquo_ground, ) from sympy.polys.densebasic import ( dup_strip, dmp_strip, dup_convert, dmp_convert, dup_degree, dmp_degree, dmp_to_dict, dmp_from_dict, dup_LC, dmp_LC, dmp_ground_LC, dup_TC, dmp_TC, dmp_zero, dmp_ground, dmp_zero_p, dup_to_raw_dict, dup_from_raw_dict, dmp_zeros ) from sympy.polys.polyerrors import ( MultivariatePolynomialError, DomainError ) from sympy.utilities import variations from math import ceil as _ceil, log as _log def dup_integrate(f, m, K): """ Computes the indefinite integral of ``f`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x = ring("x", QQ) >>> R.dup_integrate(x**2 + 2*x, 1) 1/3*x**3 + x**2 >>> R.dup_integrate(x**2 + 2*x, 2) 1/12*x**4 + 1/3*x**3 """ if m <= 0 or not f: return f g = [K.zero]*m for i, c in enumerate(reversed(f)): n = i + 1 for j in range(1, m): n *= i + j + 1 g.insert(0, K.exquo(c, K(n))) return g def dmp_integrate(f, m, u, K): """ Computes the indefinite integral of ``f`` in ``x_0`` in ``K[X]``. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x,y = ring("x,y", QQ) >>> R.dmp_integrate(x + 2*y, 1) 1/2*x**2 + 2*x*y >>> R.dmp_integrate(x + 2*y, 2) 1/6*x**3 + x**2*y """ if not u: return dup_integrate(f, m, K) if m <= 0 or dmp_zero_p(f, u): return f g, v = dmp_zeros(m, u - 1, K), u - 1 for i, c in enumerate(reversed(f)): n = i + 1 for j in range(1, m): n *= i + j + 1 g.insert(0, dmp_quo_ground(c, K(n), v, K)) return g def _rec_integrate_in(g, m, v, i, j, K): """Recursive helper for :func:`dmp_integrate_in`.""" if i == j: return dmp_integrate(g, m, v, K) w, i = v - 1, i + 1 return dmp_strip([ _rec_integrate_in(c, m, w, i, j, K) for c in g ], v) def dmp_integrate_in(f, m, j, u, K): """ Computes the indefinite integral of ``f`` in ``x_j`` in ``K[X]``. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x,y = ring("x,y", QQ) >>> R.dmp_integrate_in(x + 2*y, 1, 0) 1/2*x**2 + 2*x*y >>> R.dmp_integrate_in(x + 2*y, 1, 1) x*y + y**2 """ if j < 0 or j > u: raise IndexError("0 <= j <= u expected, got u = %d, j = %d" % (u, j)) return _rec_integrate_in(f, m, u, 0, j, K) def dup_diff(f, m, K): """ ``m``-th order derivative of a polynomial in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_diff(x**3 + 2*x**2 + 3*x + 4, 1) 3*x**2 + 4*x + 3 >>> R.dup_diff(x**3 + 2*x**2 + 3*x + 4, 2) 6*x + 4 """ if m <= 0: return f n = dup_degree(f) if n < m: return [] deriv = [] if m == 1: for coeff in f[:-m]: deriv.append(K(n)*coeff) n -= 1 else: for coeff in f[:-m]: k = n for i in range(n - 1, n - m, -1): k *= i deriv.append(K(k)*coeff) n -= 1 return dup_strip(deriv) def dmp_diff(f, m, u, K): """ ``m``-th order derivative in ``x_0`` of a polynomial in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = x*y**2 + 2*x*y + 3*x + 2*y**2 + 3*y + 1 >>> R.dmp_diff(f, 1) y**2 + 2*y + 3 >>> R.dmp_diff(f, 2) 0 """ if not u: return dup_diff(f, m, K) if m <= 0: return f n = dmp_degree(f, u) if n < m: return dmp_zero(u) deriv, v = [], u - 1 if m == 1: for coeff in f[:-m]: deriv.append(dmp_mul_ground(coeff, K(n), v, K)) n -= 1 else: for coeff in f[:-m]: k = n for i in range(n - 1, n - m, -1): k *= i deriv.append(dmp_mul_ground(coeff, K(k), v, K)) n -= 1 return dmp_strip(deriv, u) def _rec_diff_in(g, m, v, i, j, K): """Recursive helper for :func:`dmp_diff_in`.""" if i == j: return dmp_diff(g, m, v, K) w, i = v - 1, i + 1 return dmp_strip([ _rec_diff_in(c, m, w, i, j, K) for c in g ], v) def dmp_diff_in(f, m, j, u, K): """ ``m``-th order derivative in ``x_j`` of a polynomial in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = x*y**2 + 2*x*y + 3*x + 2*y**2 + 3*y + 1 >>> R.dmp_diff_in(f, 1, 0) y**2 + 2*y + 3 >>> R.dmp_diff_in(f, 1, 1) 2*x*y + 2*x + 4*y + 3 """ if j < 0 or j > u: raise IndexError("0 <= j <= %s expected, got %s" % (u, j)) return _rec_diff_in(f, m, u, 0, j, K) def dup_eval(f, a, K): """ Evaluate a polynomial at ``x = a`` in ``K[x]`` using Horner scheme. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_eval(x**2 + 2*x + 3, 2) 11 """ if not a: return dup_TC(f, K) result = K.zero for c in f: result *= a result += c return result def dmp_eval(f, a, u, K): """ Evaluate a polynomial at ``x_0 = a`` in ``K[X]`` using the Horner scheme. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_eval(2*x*y + 3*x + y + 2, 2) 5*y + 8 """ if not u: return dup_eval(f, a, K) if not a: return dmp_TC(f, K) result, v = dmp_LC(f, K), u - 1 for coeff in f[1:]: result = dmp_mul_ground(result, a, v, K) result = dmp_add(result, coeff, v, K) return result def _rec_eval_in(g, a, v, i, j, K): """Recursive helper for :func:`dmp_eval_in`.""" if i == j: return dmp_eval(g, a, v, K) v, i = v - 1, i + 1 return dmp_strip([ _rec_eval_in(c, a, v, i, j, K) for c in g ], v) def dmp_eval_in(f, a, j, u, K): """ Evaluate a polynomial at ``x_j = a`` in ``K[X]`` using the Horner scheme. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = 2*x*y + 3*x + y + 2 >>> R.dmp_eval_in(f, 2, 0) 5*y + 8 >>> R.dmp_eval_in(f, 2, 1) 7*x + 4 """ if j < 0 or j > u: raise IndexError("0 <= j <= %s expected, got %s" % (u, j)) return _rec_eval_in(f, a, u, 0, j, K) def _rec_eval_tail(g, i, A, u, K): """Recursive helper for :func:`dmp_eval_tail`.""" if i == u: return dup_eval(g, A[-1], K) else: h = [ _rec_eval_tail(c, i + 1, A, u, K) for c in g ] if i < u - len(A) + 1: return h else: return dup_eval(h, A[-u + i - 1], K) def dmp_eval_tail(f, A, u, K): """ Evaluate a polynomial at ``x_j = a_j, ...`` in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = 2*x*y + 3*x + y + 2 >>> R.dmp_eval_tail(f, [2]) 7*x + 4 >>> R.dmp_eval_tail(f, [2, 2]) 18 """ if not A: return f if dmp_zero_p(f, u): return dmp_zero(u - len(A)) e = _rec_eval_tail(f, 0, A, u, K) if u == len(A) - 1: return e else: return dmp_strip(e, u - len(A)) def _rec_diff_eval(g, m, a, v, i, j, K): """Recursive helper for :func:`dmp_diff_eval`.""" if i == j: return dmp_eval(dmp_diff(g, m, v, K), a, v, K) v, i = v - 1, i + 1 return dmp_strip([ _rec_diff_eval(c, m, a, v, i, j, K) for c in g ], v) def dmp_diff_eval_in(f, m, a, j, u, K): """ Differentiate and evaluate a polynomial in ``x_j`` at ``a`` in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = x*y**2 + 2*x*y + 3*x + 2*y**2 + 3*y + 1 >>> R.dmp_diff_eval_in(f, 1, 2, 0) y**2 + 2*y + 3 >>> R.dmp_diff_eval_in(f, 1, 2, 1) 6*x + 11 """ if j > u: raise IndexError("-%s <= j < %s expected, got %s" % (u, u, j)) if not j: return dmp_eval(dmp_diff(f, m, u, K), a, u, K) return _rec_diff_eval(f, m, a, u, 0, j, K) def dup_trunc(f, p, K): """ Reduce a ``K[x]`` polynomial modulo a constant ``p`` in ``K``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_trunc(2*x**3 + 3*x**2 + 5*x + 7, ZZ(3)) -x**3 - x + 1 """ if K.is_ZZ: g = [] for c in f: c = c % p if c > p // 2: g.append(c - p) else: g.append(c) else: g = [ c % p for c in f ] return dup_strip(g) def dmp_trunc(f, p, u, K): """ Reduce a ``K[X]`` polynomial modulo a polynomial ``p`` in ``K[Y]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = 3*x**2*y + 8*x**2 + 5*x*y + 6*x + 2*y + 3 >>> g = (y - 1).drop(x) >>> R.dmp_trunc(f, g) 11*x**2 + 11*x + 5 """ return dmp_strip([ dmp_rem(c, p, u - 1, K) for c in f ], u) def dmp_ground_trunc(f, p, u, K): """ Reduce a ``K[X]`` polynomial modulo a constant ``p`` in ``K``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = 3*x**2*y + 8*x**2 + 5*x*y + 6*x + 2*y + 3 >>> R.dmp_ground_trunc(f, ZZ(3)) -x**2 - x*y - y """ if not u: return dup_trunc(f, p, K) v = u - 1 return dmp_strip([ dmp_ground_trunc(c, p, v, K) for c in f ], u) def dup_monic(f, K): """ Divide all coefficients by ``LC(f)`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ, QQ >>> R, x = ring("x", ZZ) >>> R.dup_monic(3*x**2 + 6*x + 9) x**2 + 2*x + 3 >>> R, x = ring("x", QQ) >>> R.dup_monic(3*x**2 + 4*x + 2) x**2 + 4/3*x + 2/3 """ if not f: return f lc = dup_LC(f, K) if K.is_one(lc): return f else: return dup_exquo_ground(f, lc, K) def dmp_ground_monic(f, u, K): """ Divide all coefficients by ``LC(f)`` in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ, QQ >>> R, x,y = ring("x,y", ZZ) >>> f = 3*x**2*y + 6*x**2 + 3*x*y + 9*y + 3 >>> R.dmp_ground_monic(f) x**2*y + 2*x**2 + x*y + 3*y + 1 >>> R, x,y = ring("x,y", QQ) >>> f = 3*x**2*y + 8*x**2 + 5*x*y + 6*x + 2*y + 3 >>> R.dmp_ground_monic(f) x**2*y + 8/3*x**2 + 5/3*x*y + 2*x + 2/3*y + 1 """ if not u: return dup_monic(f, K) if dmp_zero_p(f, u): return f lc = dmp_ground_LC(f, u, K) if K.is_one(lc): return f else: return dmp_exquo_ground(f, lc, u, K) def dup_content(f, K): """ Compute the GCD of coefficients of ``f`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ, QQ >>> R, x = ring("x", ZZ) >>> f = 6*x**2 + 8*x + 12 >>> R.dup_content(f) 2 >>> R, x = ring("x", QQ) >>> f = 6*x**2 + 8*x + 12 >>> R.dup_content(f) 2 """ from sympy.polys.domains import QQ if not f: return K.zero cont = K.zero if K == QQ: for c in f: cont = K.gcd(cont, c) else: for c in f: cont = K.gcd(cont, c) if K.is_one(cont): break return cont def dmp_ground_content(f, u, K): """ Compute the GCD of coefficients of ``f`` in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ, QQ >>> R, x,y = ring("x,y", ZZ) >>> f = 2*x*y + 6*x + 4*y + 12 >>> R.dmp_ground_content(f) 2 >>> R, x,y = ring("x,y", QQ) >>> f = 2*x*y + 6*x + 4*y + 12 >>> R.dmp_ground_content(f) 2 """ from sympy.polys.domains import QQ if not u: return dup_content(f, K) if dmp_zero_p(f, u): return K.zero cont, v = K.zero, u - 1 if K == QQ: for c in f: cont = K.gcd(cont, dmp_ground_content(c, v, K)) else: for c in f: cont = K.gcd(cont, dmp_ground_content(c, v, K)) if K.is_one(cont): break return cont def dup_primitive(f, K): """ Compute content and the primitive form of ``f`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ, QQ >>> R, x = ring("x", ZZ) >>> f = 6*x**2 + 8*x + 12 >>> R.dup_primitive(f) (2, 3*x**2 + 4*x + 6) >>> R, x = ring("x", QQ) >>> f = 6*x**2 + 8*x + 12 >>> R.dup_primitive(f) (2, 3*x**2 + 4*x + 6) """ if not f: return K.zero, f cont = dup_content(f, K) if K.is_one(cont): return cont, f else: return cont, dup_quo_ground(f, cont, K) def dmp_ground_primitive(f, u, K): """ Compute content and the primitive form of ``f`` in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ, QQ >>> R, x,y = ring("x,y", ZZ) >>> f = 2*x*y + 6*x + 4*y + 12 >>> R.dmp_ground_primitive(f) (2, x*y + 3*x + 2*y + 6) >>> R, x,y = ring("x,y", QQ) >>> f = 2*x*y + 6*x + 4*y + 12 >>> R.dmp_ground_primitive(f) (2, x*y + 3*x + 2*y + 6) """ if not u: return dup_primitive(f, K) if dmp_zero_p(f, u): return K.zero, f cont = dmp_ground_content(f, u, K) if K.is_one(cont): return cont, f else: return cont, dmp_quo_ground(f, cont, u, K) def dup_extract(f, g, K): """ Extract common content from a pair of polynomials in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_extract(6*x**2 + 12*x + 18, 4*x**2 + 8*x + 12) (2, 3*x**2 + 6*x + 9, 2*x**2 + 4*x + 6) """ fc = dup_content(f, K) gc = dup_content(g, K) gcd = K.gcd(fc, gc) if not K.is_one(gcd): f = dup_quo_ground(f, gcd, K) g = dup_quo_ground(g, gcd, K) return gcd, f, g def dmp_ground_extract(f, g, u, K): """ Extract common content from a pair of polynomials in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_ground_extract(6*x*y + 12*x + 18, 4*x*y + 8*x + 12) (2, 3*x*y + 6*x + 9, 2*x*y + 4*x + 6) """ fc = dmp_ground_content(f, u, K) gc = dmp_ground_content(g, u, K) gcd = K.gcd(fc, gc) if not K.is_one(gcd): f = dmp_quo_ground(f, gcd, u, K) g = dmp_quo_ground(g, gcd, u, K) return gcd, f, g def dup_real_imag(f, K): """ Return bivariate polynomials ``f1`` and ``f2``, such that ``f = f1 + f2*I``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dup_real_imag(x**3 + x**2 + x + 1) (x**3 + x**2 - 3*x*y**2 + x - y**2 + 1, 3*x**2*y + 2*x*y - y**3 + y) """ if not K.is_ZZ and not K.is_QQ: raise DomainError("computing real and imaginary parts is not supported over %s" % K) f1 = dmp_zero(1) f2 = dmp_zero(1) if not f: return f1, f2 g = [[[K.one, K.zero]], [[K.one], []]] h = dmp_ground(f[0], 2) for c in f[1:]: h = dmp_mul(h, g, 2, K) h = dmp_add_term(h, dmp_ground(c, 1), 0, 2, K) H = dup_to_raw_dict(h) for k, h in H.items(): m = k % 4 if not m: f1 = dmp_add(f1, h, 1, K) elif m == 1: f2 = dmp_add(f2, h, 1, K) elif m == 2: f1 = dmp_sub(f1, h, 1, K) else: f2 = dmp_sub(f2, h, 1, K) return f1, f2 def dup_mirror(f, K): """ Evaluate efficiently the composition ``f(-x)`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_mirror(x**3 + 2*x**2 - 4*x + 2) -x**3 + 2*x**2 + 4*x + 2 """ f = list(f) for i in range(len(f) - 2, -1, -2): f[i] = -f[i] return f def dup_scale(f, a, K): """ Evaluate efficiently composition ``f(a*x)`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_scale(x**2 - 2*x + 1, ZZ(2)) 4*x**2 - 4*x + 1 """ f, n, b = list(f), len(f) - 1, a for i in range(n - 1, -1, -1): f[i], b = b*f[i], b*a return f def dup_shift(f, a, K): """ Evaluate efficiently Taylor shift ``f(x + a)`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_shift(x**2 - 2*x + 1, ZZ(2)) x**2 + 2*x + 1 """ f, n = list(f), len(f) - 1 for i in range(n, 0, -1): for j in range(0, i): f[j + 1] += a*f[j] return f def dup_transform(f, p, q, K): """ Evaluate functional transformation ``q**n * f(p/q)`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_transform(x**2 - 2*x + 1, x**2 + 1, x - 1) x**4 - 2*x**3 + 5*x**2 - 4*x + 4 """ if not f: return [] n = len(f) - 1 h, Q = [f[0]], [[K.one]] for i in range(0, n): Q.append(dup_mul(Q[-1], q, K)) for c, q in zip(f[1:], Q[1:]): h = dup_mul(h, p, K) q = dup_mul_ground(q, c, K) h = dup_add(h, q, K) return h def dup_compose(f, g, K): """ Evaluate functional composition ``f(g)`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_compose(x**2 + x, x - 1) x**2 - x """ if len(g) <= 1: return dup_strip([dup_eval(f, dup_LC(g, K), K)]) if not f: return [] h = [f[0]] for c in f[1:]: h = dup_mul(h, g, K) h = dup_add_term(h, c, 0, K) return h def dmp_compose(f, g, u, K): """ Evaluate functional composition ``f(g)`` in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_compose(x*y + 2*x + y, y) y**2 + 3*y """ if not u: return dup_compose(f, g, K) if dmp_zero_p(f, u): return f h = [f[0]] for c in f[1:]: h = dmp_mul(h, g, u, K) h = dmp_add_term(h, c, 0, u, K) return h def _dup_right_decompose(f, s, K): """Helper function for :func:`_dup_decompose`.""" n = len(f) - 1 lc = dup_LC(f, K) f = dup_to_raw_dict(f) g = { s: K.one } r = n // s for i in range(1, s): coeff = K.zero for j in range(0, i): if not n + j - i in f: continue if not s - j in g: continue fc, gc = f[n + j - i], g[s - j] coeff += (i - r*j)*fc*gc g[s - i] = K.quo(coeff, i*r*lc) return dup_from_raw_dict(g, K) def _dup_left_decompose(f, h, K): """Helper function for :func:`_dup_decompose`.""" g, i = {}, 0 while f: q, r = dup_div(f, h, K) if dup_degree(r) > 0: return None else: g[i] = dup_LC(r, K) f, i = q, i + 1 return dup_from_raw_dict(g, K) def _dup_decompose(f, K): """Helper function for :func:`dup_decompose`.""" df = len(f) - 1 for s in range(2, df): if df % s != 0: continue h = _dup_right_decompose(f, s, K) if h is not None: g = _dup_left_decompose(f, h, K) if g is not None: return g, h return None def dup_decompose(f, K): """ Computes functional decomposition of ``f`` in ``K[x]``. Given a univariate polynomial ``f`` with coefficients in a field of characteristic zero, returns list ``[f_1, f_2, ..., f_n]``, where:: f = f_1 o f_2 o ... f_n = f_1(f_2(... f_n)) and ``f_2, ..., f_n`` are monic and homogeneous polynomials of at least second degree. Unlike factorization, complete functional decompositions of polynomials are not unique, consider examples: 1. ``f o g = f(x + b) o (g - b)`` 2. ``x**n o x**m = x**m o x**n`` 3. ``T_n o T_m = T_m o T_n`` where ``T_n`` and ``T_m`` are Chebyshev polynomials. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_decompose(x**4 - 2*x**3 + x**2) [x**2, x**2 - x] References ========== .. [1] [Kozen89]_ """ F = [] while True: result = _dup_decompose(f, K) if result is not None: f, h = result F = [h] + F else: break return [f] + F def dmp_lift(f, u, K): """ Convert algebraic coefficients to integers in ``K[X]``. Examples ======== >>> from sympy.polys import ring, QQ >>> from sympy import I >>> K = QQ.algebraic_field(I) >>> R, x = ring("x", K) >>> f = x**2 + K([QQ(1), QQ(0)])*x + K([QQ(2), QQ(0)]) >>> R.dmp_lift(f) x**8 + 2*x**6 + 9*x**4 - 8*x**2 + 16 """ if not K.is_Algebraic: raise DomainError( 'computation can be done only in an algebraic domain') F, monoms, polys = dmp_to_dict(f, u), [], [] for monom, coeff in F.items(): if not coeff.is_ground: monoms.append(monom) perms = variations([-1, 1], len(monoms), repetition=True) for perm in perms: G = dict(F) for sign, monom in zip(perm, monoms): if sign == -1: G[monom] = -G[monom] polys.append(dmp_from_dict(G, u, K)) return dmp_convert(dmp_expand(polys, u, K), u, K, K.dom) def dup_sign_variations(f, K): """ Compute the number of sign variations of ``f`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_sign_variations(x**4 - x**2 - x + 1) 2 """ prev, k = K.zero, 0 for coeff in f: if K.is_negative(coeff*prev): k += 1 if coeff: prev = coeff return k def dup_clear_denoms(f, K0, K1=None, convert=False): """ Clear denominators, i.e. transform ``K_0`` to ``K_1``. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x = ring("x", QQ) >>> f = QQ(1,2)*x + QQ(1,3) >>> R.dup_clear_denoms(f, convert=False) (6, 3*x + 2) >>> R.dup_clear_denoms(f, convert=True) (6, 3*x + 2) """ if K1 is None: if K0.has_assoc_Ring: K1 = K0.get_ring() else: K1 = K0 common = K1.one for c in f: common = K1.lcm(common, K0.denom(c)) if not K1.is_one(common): f = dup_mul_ground(f, common, K0) if not convert: return common, f else: return common, dup_convert(f, K0, K1) def _rec_clear_denoms(g, v, K0, K1): """Recursive helper for :func:`dmp_clear_denoms`.""" common = K1.one if not v: for c in g: common = K1.lcm(common, K0.denom(c)) else: w = v - 1 for c in g: common = K1.lcm(common, _rec_clear_denoms(c, w, K0, K1)) return common def dmp_clear_denoms(f, u, K0, K1=None, convert=False): """ Clear denominators, i.e. transform ``K_0`` to ``K_1``. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x,y = ring("x,y", QQ) >>> f = QQ(1,2)*x + QQ(1,3)*y + 1 >>> R.dmp_clear_denoms(f, convert=False) (6, 3*x + 2*y + 6) >>> R.dmp_clear_denoms(f, convert=True) (6, 3*x + 2*y + 6) """ if not u: return dup_clear_denoms(f, K0, K1, convert=convert) if K1 is None: if K0.has_assoc_Ring: K1 = K0.get_ring() else: K1 = K0 common = _rec_clear_denoms(f, u, K0, K1) if not K1.is_one(common): f = dmp_mul_ground(f, common, u, K0) if not convert: return common, f else: return common, dmp_convert(f, u, K0, K1) def dup_revert(f, n, K): """ Compute ``f**(-1)`` mod ``x**n`` using Newton iteration. This function computes first ``2**n`` terms of a polynomial that is a result of inversion of a polynomial modulo ``x**n``. This is useful to efficiently compute series expansion of ``1/f``. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x = ring("x", QQ) >>> f = -QQ(1,720)*x**6 + QQ(1,24)*x**4 - QQ(1,2)*x**2 + 1 >>> R.dup_revert(f, 8) 61/720*x**6 + 5/24*x**4 + 1/2*x**2 + 1 """ g = [K.revert(dup_TC(f, K))] h = [K.one, K.zero, K.zero] N = int(_ceil(_log(n, 2))) for i in range(1, N + 1): a = dup_mul_ground(g, K(2), K) b = dup_mul(f, dup_sqr(g, K), K) g = dup_rem(dup_sub(a, b, K), h, K) h = dup_lshift(h, dup_degree(h), K) return g def dmp_revert(f, g, u, K): """ Compute ``f**(-1)`` mod ``x**n`` using Newton iteration. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x,y = ring("x,y", QQ) """ if not u: return dup_revert(f, g, K) else: raise MultivariatePolynomialError(f, g)

7a07862a4d60b2a1f661e10149139338289777fd5b1ad6fdd11b9caea786c9c6

"""User-friendly public interface to polynomial functions. """ from __future__ import print_function, division from sympy.core import ( S, Basic, Expr, I, Integer, Add, Mul, Dummy, Tuple ) from sympy.core.basic import preorder_traversal from sympy.core.compatibility import iterable, range, ordered from sympy.core.decorators import _sympifyit from sympy.core.function import Derivative from sympy.core.mul import _keep_coeff from sympy.core.relational import Relational from sympy.core.symbol import Symbol from sympy.core.sympify import sympify from sympy.logic.boolalg import BooleanAtom from sympy.polys import polyoptions as options from sympy.polys.constructor import construct_domain from sympy.polys.domains import FF, QQ, ZZ from sympy.polys.fglmtools import matrix_fglm from sympy.polys.groebnertools import groebner as _groebner from sympy.polys.monomials import Monomial from sympy.polys.orderings import monomial_key from sympy.polys.polyclasses import DMP from sympy.polys.polyerrors import ( OperationNotSupported, DomainError, CoercionFailed, UnificationFailed, GeneratorsNeeded, PolynomialError, MultivariatePolynomialError, ExactQuotientFailed, PolificationFailed, ComputationFailed, GeneratorsError, ) from sympy.polys.polyutils import ( basic_from_dict, _sort_gens, _unify_gens, _dict_reorder, _dict_from_expr, _parallel_dict_from_expr, ) from sympy.polys.rationaltools import together from sympy.polys.rootisolation import dup_isolate_real_roots_list from sympy.utilities import group, sift, public, filldedent # Required to avoid errors import sympy.polys import mpmath from mpmath.libmp.libhyper import NoConvergence @public class Poly(Expr): """ Generic class for representing and operating on polynomial expressions. Subclasses Expr class. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y Create a univariate polynomial: >>> Poly(x*(x**2 + x - 1)**2) Poly(x**5 + 2*x**4 - x**3 - 2*x**2 + x, x, domain='ZZ') Create a univariate polynomial with specific domain: >>> from sympy import sqrt >>> Poly(x**2 + 2*x + sqrt(3), domain='R') Poly(1.0*x**2 + 2.0*x + 1.73205080756888, x, domain='RR') Create a multivariate polynomial: >>> Poly(y*x**2 + x*y + 1) Poly(x**2*y + x*y + 1, x, y, domain='ZZ') Create a univariate polynomial, where y is a constant: >>> Poly(y*x**2 + x*y + 1,x) Poly(y*x**2 + y*x + 1, x, domain='ZZ[y]') You can evaluate the above polynomial as a function of y: >>> Poly(y*x**2 + x*y + 1,x).eval(2) 6*y + 1 See Also ======== sympy.core.expr.Expr """ __slots__ = ['rep', 'gens'] is_commutative = True is_Poly = True _op_priority = 10.001 def __new__(cls, rep, *gens, **args): """Create a new polynomial instance out of something useful. """ opt = options.build_options(gens, args) if 'order' in opt: raise NotImplementedError("'order' keyword is not implemented yet") if iterable(rep, exclude=str): if isinstance(rep, dict): return cls._from_dict(rep, opt) else: return cls._from_list(list(rep), opt) else: rep = sympify(rep) if rep.is_Poly: return cls._from_poly(rep, opt) else: return cls._from_expr(rep, opt) @classmethod def new(cls, rep, *gens): """Construct :class:`Poly` instance from raw representation. """ if not isinstance(rep, DMP): raise PolynomialError( "invalid polynomial representation: %s" % rep) elif rep.lev != len(gens) - 1: raise PolynomialError("invalid arguments: %s, %s" % (rep, gens)) obj = Basic.__new__(cls) obj.rep = rep obj.gens = gens return obj @classmethod def from_dict(cls, rep, *gens, **args): """Construct a polynomial from a ``dict``. """ opt = options.build_options(gens, args) return cls._from_dict(rep, opt) @classmethod def from_list(cls, rep, *gens, **args): """Construct a polynomial from a ``list``. """ opt = options.build_options(gens, args) return cls._from_list(rep, opt) @classmethod def from_poly(cls, rep, *gens, **args): """Construct a polynomial from a polynomial. """ opt = options.build_options(gens, args) return cls._from_poly(rep, opt) @classmethod def from_expr(cls, rep, *gens, **args): """Construct a polynomial from an expression. """ opt = options.build_options(gens, args) return cls._from_expr(rep, opt) @classmethod def _from_dict(cls, rep, opt): """Construct a polynomial from a ``dict``. """ gens = opt.gens if not gens: raise GeneratorsNeeded( "can't initialize from 'dict' without generators") level = len(gens) - 1 domain = opt.domain if domain is None: domain, rep = construct_domain(rep, opt=opt) else: for monom, coeff in rep.items(): rep[monom] = domain.convert(coeff) return cls.new(DMP.from_dict(rep, level, domain), *gens) @classmethod def _from_list(cls, rep, opt): """Construct a polynomial from a ``list``. """ gens = opt.gens if not gens: raise GeneratorsNeeded( "can't initialize from 'list' without generators") elif len(gens) != 1: raise MultivariatePolynomialError( "'list' representation not supported") level = len(gens) - 1 domain = opt.domain if domain is None: domain, rep = construct_domain(rep, opt=opt) else: rep = list(map(domain.convert, rep)) return cls.new(DMP.from_list(rep, level, domain), *gens) @classmethod def _from_poly(cls, rep, opt): """Construct a polynomial from a polynomial. """ if cls != rep.__class__: rep = cls.new(rep.rep, *rep.gens) gens = opt.gens field = opt.field domain = opt.domain if gens and rep.gens != gens: if set(rep.gens) != set(gens): return cls._from_expr(rep.as_expr(), opt) else: rep = rep.reorder(*gens) if 'domain' in opt and domain: rep = rep.set_domain(domain) elif field is True: rep = rep.to_field() return rep @classmethod def _from_expr(cls, rep, opt): """Construct a polynomial from an expression. """ rep, opt = _dict_from_expr(rep, opt) return cls._from_dict(rep, opt) def _hashable_content(self): """Allow SymPy to hash Poly instances. """ return (self.rep, self.gens) def __hash__(self): return super(Poly, self).__hash__() @property def free_symbols(self): """ Free symbols of a polynomial expression. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y, z >>> Poly(x**2 + 1).free_symbols {x} >>> Poly(x**2 + y).free_symbols {x, y} >>> Poly(x**2 + y, x).free_symbols {x, y} >>> Poly(x**2 + y, x, z).free_symbols {x, y} """ symbols = set() gens = self.gens for i in range(len(gens)): for monom in self.monoms(): if monom[i]: symbols |= gens[i].free_symbols break return symbols | self.free_symbols_in_domain @property def free_symbols_in_domain(self): """ Free symbols of the domain of ``self``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**2 + 1).free_symbols_in_domain set() >>> Poly(x**2 + y).free_symbols_in_domain set() >>> Poly(x**2 + y, x).free_symbols_in_domain {y} """ domain, symbols = self.rep.dom, set() if domain.is_Composite: for gen in domain.symbols: symbols |= gen.free_symbols elif domain.is_EX: for coeff in self.coeffs(): symbols |= coeff.free_symbols return symbols @property def args(self): """ Don't mess up with the core. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + 1, x).args (x**2 + 1,) """ return (self.as_expr(),) @property def gen(self): """ Return the principal generator. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + 1, x).gen x """ return self.gens[0] @property def domain(self): """Get the ground domain of ``self``. """ return self.get_domain() @property def zero(self): """Return zero polynomial with ``self``'s properties. """ return self.new(self.rep.zero(self.rep.lev, self.rep.dom), *self.gens) @property def one(self): """Return one polynomial with ``self``'s properties. """ return self.new(self.rep.one(self.rep.lev, self.rep.dom), *self.gens) @property def unit(self): """Return unit polynomial with ``self``'s properties. """ return self.new(self.rep.unit(self.rep.lev, self.rep.dom), *self.gens) def unify(f, g): """ Make ``f`` and ``g`` belong to the same domain. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> f, g = Poly(x/2 + 1), Poly(2*x + 1) >>> f Poly(1/2*x + 1, x, domain='QQ') >>> g Poly(2*x + 1, x, domain='ZZ') >>> F, G = f.unify(g) >>> F Poly(1/2*x + 1, x, domain='QQ') >>> G Poly(2*x + 1, x, domain='QQ') """ _, per, F, G = f._unify(g) return per(F), per(G) def _unify(f, g): g = sympify(g) if not g.is_Poly: try: return f.rep.dom, f.per, f.rep, f.rep.per(f.rep.dom.from_sympy(g)) except CoercionFailed: raise UnificationFailed("can't unify %s with %s" % (f, g)) if isinstance(f.rep, DMP) and isinstance(g.rep, DMP): gens = _unify_gens(f.gens, g.gens) dom, lev = f.rep.dom.unify(g.rep.dom, gens), len(gens) - 1 if f.gens != gens: f_monoms, f_coeffs = _dict_reorder( f.rep.to_dict(), f.gens, gens) if f.rep.dom != dom: f_coeffs = [dom.convert(c, f.rep.dom) for c in f_coeffs] F = DMP(dict(list(zip(f_monoms, f_coeffs))), dom, lev) else: F = f.rep.convert(dom) if g.gens != gens: g_monoms, g_coeffs = _dict_reorder( g.rep.to_dict(), g.gens, gens) if g.rep.dom != dom: g_coeffs = [dom.convert(c, g.rep.dom) for c in g_coeffs] G = DMP(dict(list(zip(g_monoms, g_coeffs))), dom, lev) else: G = g.rep.convert(dom) else: raise UnificationFailed("can't unify %s with %s" % (f, g)) cls = f.__class__ def per(rep, dom=dom, gens=gens, remove=None): if remove is not None: gens = gens[:remove] + gens[remove + 1:] if not gens: return dom.to_sympy(rep) return cls.new(rep, *gens) return dom, per, F, G def per(f, rep, gens=None, remove=None): """ Create a Poly out of the given representation. Examples ======== >>> from sympy import Poly, ZZ >>> from sympy.abc import x, y >>> from sympy.polys.polyclasses import DMP >>> a = Poly(x**2 + 1) >>> a.per(DMP([ZZ(1), ZZ(1)], ZZ), gens=[y]) Poly(y + 1, y, domain='ZZ') """ if gens is None: gens = f.gens if remove is not None: gens = gens[:remove] + gens[remove + 1:] if not gens: return f.rep.dom.to_sympy(rep) return f.__class__.new(rep, *gens) def set_domain(f, domain): """Set the ground domain of ``f``. """ opt = options.build_options(f.gens, {'domain': domain}) return f.per(f.rep.convert(opt.domain)) def get_domain(f): """Get the ground domain of ``f``. """ return f.rep.dom def set_modulus(f, modulus): """ Set the modulus of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(5*x**2 + 2*x - 1, x).set_modulus(2) Poly(x**2 + 1, x, modulus=2) """ modulus = options.Modulus.preprocess(modulus) return f.set_domain(FF(modulus)) def get_modulus(f): """ Get the modulus of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + 1, modulus=2).get_modulus() 2 """ domain = f.get_domain() if domain.is_FiniteField: return Integer(domain.characteristic()) else: raise PolynomialError("not a polynomial over a Galois field") def _eval_subs(f, old, new): """Internal implementation of :func:`subs`. """ if old in f.gens: if new.is_number: return f.eval(old, new) else: try: return f.replace(old, new) except PolynomialError: pass return f.as_expr().subs(old, new) def exclude(f): """ Remove unnecessary generators from ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import a, b, c, d, x >>> Poly(a + x, a, b, c, d, x).exclude() Poly(a + x, a, x, domain='ZZ') """ J, new = f.rep.exclude() gens = [] for j in range(len(f.gens)): if j not in J: gens.append(f.gens[j]) return f.per(new, gens=gens) def replace(f, x, y=None, *_ignore): # XXX this does not match Basic's signature """ Replace ``x`` with ``y`` in generators list. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**2 + 1, x).replace(x, y) Poly(y**2 + 1, y, domain='ZZ') """ if y is None: if f.is_univariate: x, y = f.gen, x else: raise PolynomialError( "syntax supported only in univariate case") if x == y or x not in f.gens: return f if x in f.gens and y not in f.gens: dom = f.get_domain() if not dom.is_Composite or y not in dom.symbols: gens = list(f.gens) gens[gens.index(x)] = y return f.per(f.rep, gens=gens) raise PolynomialError("can't replace %s with %s in %s" % (x, y, f)) def reorder(f, *gens, **args): """ Efficiently apply new order of generators. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**2 + x*y**2, x, y).reorder(y, x) Poly(y**2*x + x**2, y, x, domain='ZZ') """ opt = options.Options((), args) if not gens: gens = _sort_gens(f.gens, opt=opt) elif set(f.gens) != set(gens): raise PolynomialError( "generators list can differ only up to order of elements") rep = dict(list(zip(*_dict_reorder(f.rep.to_dict(), f.gens, gens)))) return f.per(DMP(rep, f.rep.dom, len(gens) - 1), gens=gens) def ltrim(f, gen): """ Remove dummy generators from ``f`` that are to the left of specified ``gen`` in the generators as ordered. When ``gen`` is an integer, it refers to the generator located at that position within the tuple of generators of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y, z >>> Poly(y**2 + y*z**2, x, y, z).ltrim(y) Poly(y**2 + y*z**2, y, z, domain='ZZ') >>> Poly(z, x, y, z).ltrim(-1) Poly(z, z, domain='ZZ') """ rep = f.as_dict(native=True) j = f._gen_to_level(gen) terms = {} for monom, coeff in rep.items(): if any(i for i in monom[:j]): # some generator is used in the portion to be trimmed raise PolynomialError("can't left trim %s" % f) terms[monom[j:]] = coeff gens = f.gens[j:] return f.new(DMP.from_dict(terms, len(gens) - 1, f.rep.dom), *gens) def has_only_gens(f, *gens): """ Return ``True`` if ``Poly(f, *gens)`` retains ground domain. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y, z >>> Poly(x*y + 1, x, y, z).has_only_gens(x, y) True >>> Poly(x*y + z, x, y, z).has_only_gens(x, y) False """ indices = set() for gen in gens: try: index = f.gens.index(gen) except ValueError: raise GeneratorsError( "%s doesn't have %s as generator" % (f, gen)) else: indices.add(index) for monom in f.monoms(): for i, elt in enumerate(monom): if i not in indices and elt: return False return True def to_ring(f): """ Make the ground domain a ring. Examples ======== >>> from sympy import Poly, QQ >>> from sympy.abc import x >>> Poly(x**2 + 1, domain=QQ).to_ring() Poly(x**2 + 1, x, domain='ZZ') """ if hasattr(f.rep, 'to_ring'): result = f.rep.to_ring() else: # pragma: no cover raise OperationNotSupported(f, 'to_ring') return f.per(result) def to_field(f): """ Make the ground domain a field. Examples ======== >>> from sympy import Poly, ZZ >>> from sympy.abc import x >>> Poly(x**2 + 1, x, domain=ZZ).to_field() Poly(x**2 + 1, x, domain='QQ') """ if hasattr(f.rep, 'to_field'): result = f.rep.to_field() else: # pragma: no cover raise OperationNotSupported(f, 'to_field') return f.per(result) def to_exact(f): """ Make the ground domain exact. Examples ======== >>> from sympy import Poly, RR >>> from sympy.abc import x >>> Poly(x**2 + 1.0, x, domain=RR).to_exact() Poly(x**2 + 1, x, domain='QQ') """ if hasattr(f.rep, 'to_exact'): result = f.rep.to_exact() else: # pragma: no cover raise OperationNotSupported(f, 'to_exact') return f.per(result) def retract(f, field=None): """ Recalculate the ground domain of a polynomial. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> f = Poly(x**2 + 1, x, domain='QQ[y]') >>> f Poly(x**2 + 1, x, domain='QQ[y]') >>> f.retract() Poly(x**2 + 1, x, domain='ZZ') >>> f.retract(field=True) Poly(x**2 + 1, x, domain='QQ') """ dom, rep = construct_domain(f.as_dict(zero=True), field=field, composite=f.domain.is_Composite or None) return f.from_dict(rep, f.gens, domain=dom) def slice(f, x, m, n=None): """Take a continuous subsequence of terms of ``f``. """ if n is None: j, m, n = 0, x, m else: j = f._gen_to_level(x) m, n = int(m), int(n) if hasattr(f.rep, 'slice'): result = f.rep.slice(m, n, j) else: # pragma: no cover raise OperationNotSupported(f, 'slice') return f.per(result) def coeffs(f, order=None): """ Returns all non-zero coefficients from ``f`` in lex order. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**3 + 2*x + 3, x).coeffs() [1, 2, 3] See Also ======== all_coeffs coeff_monomial nth """ return [f.rep.dom.to_sympy(c) for c in f.rep.coeffs(order=order)] def monoms(f, order=None): """ Returns all non-zero monomials from ``f`` in lex order. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**2 + 2*x*y**2 + x*y + 3*y, x, y).monoms() [(2, 0), (1, 2), (1, 1), (0, 1)] See Also ======== all_monoms """ return f.rep.monoms(order=order) def terms(f, order=None): """ Returns all non-zero terms from ``f`` in lex order. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**2 + 2*x*y**2 + x*y + 3*y, x, y).terms() [((2, 0), 1), ((1, 2), 2), ((1, 1), 1), ((0, 1), 3)] See Also ======== all_terms """ return [(m, f.rep.dom.to_sympy(c)) for m, c in f.rep.terms(order=order)] def all_coeffs(f): """ Returns all coefficients from a univariate polynomial ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**3 + 2*x - 1, x).all_coeffs() [1, 0, 2, -1] """ return [f.rep.dom.to_sympy(c) for c in f.rep.all_coeffs()] def all_monoms(f): """ Returns all monomials from a univariate polynomial ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**3 + 2*x - 1, x).all_monoms() [(3,), (2,), (1,), (0,)] See Also ======== all_terms """ return f.rep.all_monoms() def all_terms(f): """ Returns all terms from a univariate polynomial ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**3 + 2*x - 1, x).all_terms() [((3,), 1), ((2,), 0), ((1,), 2), ((0,), -1)] """ return [(m, f.rep.dom.to_sympy(c)) for m, c in f.rep.all_terms()] def termwise(f, func, *gens, **args): """ Apply a function to all terms of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> def func(k, coeff): ... k = k[0] ... return coeff//10**(2-k) >>> Poly(x**2 + 20*x + 400).termwise(func) Poly(x**2 + 2*x + 4, x, domain='ZZ') """ terms = {} for monom, coeff in f.terms(): result = func(monom, coeff) if isinstance(result, tuple): monom, coeff = result else: coeff = result if coeff: if monom not in terms: terms[monom] = coeff else: raise PolynomialError( "%s monomial was generated twice" % monom) return f.from_dict(terms, *(gens or f.gens), **args) def length(f): """ Returns the number of non-zero terms in ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + 2*x - 1).length() 3 """ return len(f.as_dict()) def as_dict(f, native=False, zero=False): """ Switch to a ``dict`` representation. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**2 + 2*x*y**2 - y, x, y).as_dict() {(0, 1): -1, (1, 2): 2, (2, 0): 1} """ if native: return f.rep.to_dict(zero=zero) else: return f.rep.to_sympy_dict(zero=zero) def as_list(f, native=False): """Switch to a ``list`` representation. """ if native: return f.rep.to_list() else: return f.rep.to_sympy_list() def as_expr(f, *gens): """ Convert a Poly instance to an Expr instance. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> f = Poly(x**2 + 2*x*y**2 - y, x, y) >>> f.as_expr() x**2 + 2*x*y**2 - y >>> f.as_expr({x: 5}) 10*y**2 - y + 25 >>> f.as_expr(5, 6) 379 """ if not gens: gens = f.gens elif len(gens) == 1 and isinstance(gens[0], dict): mapping = gens[0] gens = list(f.gens) for gen, value in mapping.items(): try: index = gens.index(gen) except ValueError: raise GeneratorsError( "%s doesn't have %s as generator" % (f, gen)) else: gens[index] = value return basic_from_dict(f.rep.to_sympy_dict(), *gens) def lift(f): """ Convert algebraic coefficients to rationals. Examples ======== >>> from sympy import Poly, I >>> from sympy.abc import x >>> Poly(x**2 + I*x + 1, x, extension=I).lift() Poly(x**4 + 3*x**2 + 1, x, domain='QQ') """ if hasattr(f.rep, 'lift'): result = f.rep.lift() else: # pragma: no cover raise OperationNotSupported(f, 'lift') return f.per(result) def deflate(f): """ Reduce degree of ``f`` by mapping ``x_i**m`` to ``y_i``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**6*y**2 + x**3 + 1, x, y).deflate() ((3, 2), Poly(x**2*y + x + 1, x, y, domain='ZZ')) """ if hasattr(f.rep, 'deflate'): J, result = f.rep.deflate() else: # pragma: no cover raise OperationNotSupported(f, 'deflate') return J, f.per(result) def inject(f, front=False): """ Inject ground domain generators into ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> f = Poly(x**2*y + x*y**3 + x*y + 1, x) >>> f.inject() Poly(x**2*y + x*y**3 + x*y + 1, x, y, domain='ZZ') >>> f.inject(front=True) Poly(y**3*x + y*x**2 + y*x + 1, y, x, domain='ZZ') """ dom = f.rep.dom if dom.is_Numerical: return f elif not dom.is_Poly: raise DomainError("can't inject generators over %s" % dom) if hasattr(f.rep, 'inject'): result = f.rep.inject(front=front) else: # pragma: no cover raise OperationNotSupported(f, 'inject') if front: gens = dom.symbols + f.gens else: gens = f.gens + dom.symbols return f.new(result, *gens) def eject(f, *gens): """ Eject selected generators into the ground domain. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> f = Poly(x**2*y + x*y**3 + x*y + 1, x, y) >>> f.eject(x) Poly(x*y**3 + (x**2 + x)*y + 1, y, domain='ZZ[x]') >>> f.eject(y) Poly(y*x**2 + (y**3 + y)*x + 1, x, domain='ZZ[y]') """ dom = f.rep.dom if not dom.is_Numerical: raise DomainError("can't eject generators over %s" % dom) k = len(gens) if f.gens[:k] == gens: _gens, front = f.gens[k:], True elif f.gens[-k:] == gens: _gens, front = f.gens[:-k], False else: raise NotImplementedError( "can only eject front or back generators") dom = dom.inject(*gens) if hasattr(f.rep, 'eject'): result = f.rep.eject(dom, front=front) else: # pragma: no cover raise OperationNotSupported(f, 'eject') return f.new(result, *_gens) def terms_gcd(f): """ Remove GCD of terms from the polynomial ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**6*y**2 + x**3*y, x, y).terms_gcd() ((3, 1), Poly(x**3*y + 1, x, y, domain='ZZ')) """ if hasattr(f.rep, 'terms_gcd'): J, result = f.rep.terms_gcd() else: # pragma: no cover raise OperationNotSupported(f, 'terms_gcd') return J, f.per(result) def add_ground(f, coeff): """ Add an element of the ground domain to ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x + 1).add_ground(2) Poly(x + 3, x, domain='ZZ') """ if hasattr(f.rep, 'add_ground'): result = f.rep.add_ground(coeff) else: # pragma: no cover raise OperationNotSupported(f, 'add_ground') return f.per(result) def sub_ground(f, coeff): """ Subtract an element of the ground domain from ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x + 1).sub_ground(2) Poly(x - 1, x, domain='ZZ') """ if hasattr(f.rep, 'sub_ground'): result = f.rep.sub_ground(coeff) else: # pragma: no cover raise OperationNotSupported(f, 'sub_ground') return f.per(result) def mul_ground(f, coeff): """ Multiply ``f`` by a an element of the ground domain. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x + 1).mul_ground(2) Poly(2*x + 2, x, domain='ZZ') """ if hasattr(f.rep, 'mul_ground'): result = f.rep.mul_ground(coeff) else: # pragma: no cover raise OperationNotSupported(f, 'mul_ground') return f.per(result) def quo_ground(f, coeff): """ Quotient of ``f`` by a an element of the ground domain. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(2*x + 4).quo_ground(2) Poly(x + 2, x, domain='ZZ') >>> Poly(2*x + 3).quo_ground(2) Poly(x + 1, x, domain='ZZ') """ if hasattr(f.rep, 'quo_ground'): result = f.rep.quo_ground(coeff) else: # pragma: no cover raise OperationNotSupported(f, 'quo_ground') return f.per(result) def exquo_ground(f, coeff): """ Exact quotient of ``f`` by a an element of the ground domain. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(2*x + 4).exquo_ground(2) Poly(x + 2, x, domain='ZZ') >>> Poly(2*x + 3).exquo_ground(2) Traceback (most recent call last): ... ExactQuotientFailed: 2 does not divide 3 in ZZ """ if hasattr(f.rep, 'exquo_ground'): result = f.rep.exquo_ground(coeff) else: # pragma: no cover raise OperationNotSupported(f, 'exquo_ground') return f.per(result) def abs(f): """ Make all coefficients in ``f`` positive. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 - 1, x).abs() Poly(x**2 + 1, x, domain='ZZ') """ if hasattr(f.rep, 'abs'): result = f.rep.abs() else: # pragma: no cover raise OperationNotSupported(f, 'abs') return f.per(result) def neg(f): """ Negate all coefficients in ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 - 1, x).neg() Poly(-x**2 + 1, x, domain='ZZ') >>> -Poly(x**2 - 1, x) Poly(-x**2 + 1, x, domain='ZZ') """ if hasattr(f.rep, 'neg'): result = f.rep.neg() else: # pragma: no cover raise OperationNotSupported(f, 'neg') return f.per(result) def add(f, g): """ Add two polynomials ``f`` and ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + 1, x).add(Poly(x - 2, x)) Poly(x**2 + x - 1, x, domain='ZZ') >>> Poly(x**2 + 1, x) + Poly(x - 2, x) Poly(x**2 + x - 1, x, domain='ZZ') """ g = sympify(g) if not g.is_Poly: return f.add_ground(g) _, per, F, G = f._unify(g) if hasattr(f.rep, 'add'): result = F.add(G) else: # pragma: no cover raise OperationNotSupported(f, 'add') return per(result) def sub(f, g): """ Subtract two polynomials ``f`` and ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + 1, x).sub(Poly(x - 2, x)) Poly(x**2 - x + 3, x, domain='ZZ') >>> Poly(x**2 + 1, x) - Poly(x - 2, x) Poly(x**2 - x + 3, x, domain='ZZ') """ g = sympify(g) if not g.is_Poly: return f.sub_ground(g) _, per, F, G = f._unify(g) if hasattr(f.rep, 'sub'): result = F.sub(G) else: # pragma: no cover raise OperationNotSupported(f, 'sub') return per(result) def mul(f, g): """ Multiply two polynomials ``f`` and ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + 1, x).mul(Poly(x - 2, x)) Poly(x**3 - 2*x**2 + x - 2, x, domain='ZZ') >>> Poly(x**2 + 1, x)*Poly(x - 2, x) Poly(x**3 - 2*x**2 + x - 2, x, domain='ZZ') """ g = sympify(g) if not g.is_Poly: return f.mul_ground(g) _, per, F, G = f._unify(g) if hasattr(f.rep, 'mul'): result = F.mul(G) else: # pragma: no cover raise OperationNotSupported(f, 'mul') return per(result) def sqr(f): """ Square a polynomial ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x - 2, x).sqr() Poly(x**2 - 4*x + 4, x, domain='ZZ') >>> Poly(x - 2, x)**2 Poly(x**2 - 4*x + 4, x, domain='ZZ') """ if hasattr(f.rep, 'sqr'): result = f.rep.sqr() else: # pragma: no cover raise OperationNotSupported(f, 'sqr') return f.per(result) def pow(f, n): """ Raise ``f`` to a non-negative power ``n``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x - 2, x).pow(3) Poly(x**3 - 6*x**2 + 12*x - 8, x, domain='ZZ') >>> Poly(x - 2, x)**3 Poly(x**3 - 6*x**2 + 12*x - 8, x, domain='ZZ') """ n = int(n) if hasattr(f.rep, 'pow'): result = f.rep.pow(n) else: # pragma: no cover raise OperationNotSupported(f, 'pow') return f.per(result) def pdiv(f, g): """ Polynomial pseudo-division of ``f`` by ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + 1, x).pdiv(Poly(2*x - 4, x)) (Poly(2*x + 4, x, domain='ZZ'), Poly(20, x, domain='ZZ')) """ _, per, F, G = f._unify(g) if hasattr(f.rep, 'pdiv'): q, r = F.pdiv(G) else: # pragma: no cover raise OperationNotSupported(f, 'pdiv') return per(q), per(r) def prem(f, g): """ Polynomial pseudo-remainder of ``f`` by ``g``. Caveat: The function prem(f, g, x) can be safely used to compute in Z[x] _only_ subresultant polynomial remainder sequences (prs's). To safely compute Euclidean and Sturmian prs's in Z[x] employ anyone of the corresponding functions found in the module sympy.polys.subresultants_qq_zz. The functions in the module with suffix _pg compute prs's in Z[x] employing rem(f, g, x), whereas the functions with suffix _amv compute prs's in Z[x] employing rem_z(f, g, x). The function rem_z(f, g, x) differs from prem(f, g, x) in that to compute the remainder polynomials in Z[x] it premultiplies the divident times the absolute value of the leading coefficient of the divisor raised to the power degree(f, x) - degree(g, x) + 1. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + 1, x).prem(Poly(2*x - 4, x)) Poly(20, x, domain='ZZ') """ _, per, F, G = f._unify(g) if hasattr(f.rep, 'prem'): result = F.prem(G) else: # pragma: no cover raise OperationNotSupported(f, 'prem') return per(result) def pquo(f, g): """ Polynomial pseudo-quotient of ``f`` by ``g``. See the Caveat note in the function prem(f, g). Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + 1, x).pquo(Poly(2*x - 4, x)) Poly(2*x + 4, x, domain='ZZ') >>> Poly(x**2 - 1, x).pquo(Poly(2*x - 2, x)) Poly(2*x + 2, x, domain='ZZ') """ _, per, F, G = f._unify(g) if hasattr(f.rep, 'pquo'): result = F.pquo(G) else: # pragma: no cover raise OperationNotSupported(f, 'pquo') return per(result) def pexquo(f, g): """ Polynomial exact pseudo-quotient of ``f`` by ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 - 1, x).pexquo(Poly(2*x - 2, x)) Poly(2*x + 2, x, domain='ZZ') >>> Poly(x**2 + 1, x).pexquo(Poly(2*x - 4, x)) Traceback (most recent call last): ... ExactQuotientFailed: 2*x - 4 does not divide x**2 + 1 """ _, per, F, G = f._unify(g) if hasattr(f.rep, 'pexquo'): try: result = F.pexquo(G) except ExactQuotientFailed as exc: raise exc.new(f.as_expr(), g.as_expr()) else: # pragma: no cover raise OperationNotSupported(f, 'pexquo') return per(result) def div(f, g, auto=True): """ Polynomial division with remainder of ``f`` by ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + 1, x).div(Poly(2*x - 4, x)) (Poly(1/2*x + 1, x, domain='QQ'), Poly(5, x, domain='QQ')) >>> Poly(x**2 + 1, x).div(Poly(2*x - 4, x), auto=False) (Poly(0, x, domain='ZZ'), Poly(x**2 + 1, x, domain='ZZ')) """ dom, per, F, G = f._unify(g) retract = False if auto and dom.is_Ring and not dom.is_Field: F, G = F.to_field(), G.to_field() retract = True if hasattr(f.rep, 'div'): q, r = F.div(G) else: # pragma: no cover raise OperationNotSupported(f, 'div') if retract: try: Q, R = q.to_ring(), r.to_ring() except CoercionFailed: pass else: q, r = Q, R return per(q), per(r) def rem(f, g, auto=True): """ Computes the polynomial remainder of ``f`` by ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + 1, x).rem(Poly(2*x - 4, x)) Poly(5, x, domain='ZZ') >>> Poly(x**2 + 1, x).rem(Poly(2*x - 4, x), auto=False) Poly(x**2 + 1, x, domain='ZZ') """ dom, per, F, G = f._unify(g) retract = False if auto and dom.is_Ring and not dom.is_Field: F, G = F.to_field(), G.to_field() retract = True if hasattr(f.rep, 'rem'): r = F.rem(G) else: # pragma: no cover raise OperationNotSupported(f, 'rem') if retract: try: r = r.to_ring() except CoercionFailed: pass return per(r) def quo(f, g, auto=True): """ Computes polynomial quotient of ``f`` by ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + 1, x).quo(Poly(2*x - 4, x)) Poly(1/2*x + 1, x, domain='QQ') >>> Poly(x**2 - 1, x).quo(Poly(x - 1, x)) Poly(x + 1, x, domain='ZZ') """ dom, per, F, G = f._unify(g) retract = False if auto and dom.is_Ring and not dom.is_Field: F, G = F.to_field(), G.to_field() retract = True if hasattr(f.rep, 'quo'): q = F.quo(G) else: # pragma: no cover raise OperationNotSupported(f, 'quo') if retract: try: q = q.to_ring() except CoercionFailed: pass return per(q) def exquo(f, g, auto=True): """ Computes polynomial exact quotient of ``f`` by ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 - 1, x).exquo(Poly(x - 1, x)) Poly(x + 1, x, domain='ZZ') >>> Poly(x**2 + 1, x).exquo(Poly(2*x - 4, x)) Traceback (most recent call last): ... ExactQuotientFailed: 2*x - 4 does not divide x**2 + 1 """ dom, per, F, G = f._unify(g) retract = False if auto and dom.is_Ring and not dom.is_Field: F, G = F.to_field(), G.to_field() retract = True if hasattr(f.rep, 'exquo'): try: q = F.exquo(G) except ExactQuotientFailed as exc: raise exc.new(f.as_expr(), g.as_expr()) else: # pragma: no cover raise OperationNotSupported(f, 'exquo') if retract: try: q = q.to_ring() except CoercionFailed: pass return per(q) def _gen_to_level(f, gen): """Returns level associated with the given generator. """ if isinstance(gen, int): length = len(f.gens) if -length <= gen < length: if gen < 0: return length + gen else: return gen else: raise PolynomialError("-%s <= gen < %s expected, got %s" % (length, length, gen)) else: try: return f.gens.index(sympify(gen)) except ValueError: raise PolynomialError( "a valid generator expected, got %s" % gen) def degree(f, gen=0): """ Returns degree of ``f`` in ``x_j``. The degree of 0 is negative infinity. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**2 + y*x + 1, x, y).degree() 2 >>> Poly(x**2 + y*x + y, x, y).degree(y) 1 >>> Poly(0, x).degree() -oo """ j = f._gen_to_level(gen) if hasattr(f.rep, 'degree'): return f.rep.degree(j) else: # pragma: no cover raise OperationNotSupported(f, 'degree') def degree_list(f): """ Returns a list of degrees of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**2 + y*x + 1, x, y).degree_list() (2, 1) """ if hasattr(f.rep, 'degree_list'): return f.rep.degree_list() else: # pragma: no cover raise OperationNotSupported(f, 'degree_list') def total_degree(f): """ Returns the total degree of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**2 + y*x + 1, x, y).total_degree() 2 >>> Poly(x + y**5, x, y).total_degree() 5 """ if hasattr(f.rep, 'total_degree'): return f.rep.total_degree() else: # pragma: no cover raise OperationNotSupported(f, 'total_degree') def homogenize(f, s): """ Returns the homogeneous polynomial of ``f``. A homogeneous polynomial is a polynomial whose all monomials with non-zero coefficients have the same total degree. If you only want to check if a polynomial is homogeneous, then use :func:`Poly.is_homogeneous`. If you want not only to check if a polynomial is homogeneous but also compute its homogeneous order, then use :func:`Poly.homogeneous_order`. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y, z >>> f = Poly(x**5 + 2*x**2*y**2 + 9*x*y**3) >>> f.homogenize(z) Poly(x**5 + 2*x**2*y**2*z + 9*x*y**3*z, x, y, z, domain='ZZ') """ if not isinstance(s, Symbol): raise TypeError("``Symbol`` expected, got %s" % type(s)) if s in f.gens: i = f.gens.index(s) gens = f.gens else: i = len(f.gens) gens = f.gens + (s,) if hasattr(f.rep, 'homogenize'): return f.per(f.rep.homogenize(i), gens=gens) raise OperationNotSupported(f, 'homogeneous_order') def homogeneous_order(f): """ Returns the homogeneous order of ``f``. A homogeneous polynomial is a polynomial whose all monomials with non-zero coefficients have the same total degree. This degree is the homogeneous order of ``f``. If you only want to check if a polynomial is homogeneous, then use :func:`Poly.is_homogeneous`. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> f = Poly(x**5 + 2*x**3*y**2 + 9*x*y**4) >>> f.homogeneous_order() 5 """ if hasattr(f.rep, 'homogeneous_order'): return f.rep.homogeneous_order() else: # pragma: no cover raise OperationNotSupported(f, 'homogeneous_order') def LC(f, order=None): """ Returns the leading coefficient of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(4*x**3 + 2*x**2 + 3*x, x).LC() 4 """ if order is not None: return f.coeffs(order)[0] if hasattr(f.rep, 'LC'): result = f.rep.LC() else: # pragma: no cover raise OperationNotSupported(f, 'LC') return f.rep.dom.to_sympy(result) def TC(f): """ Returns the trailing coefficient of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**3 + 2*x**2 + 3*x, x).TC() 0 """ if hasattr(f.rep, 'TC'): result = f.rep.TC() else: # pragma: no cover raise OperationNotSupported(f, 'TC') return f.rep.dom.to_sympy(result) def EC(f, order=None): """ Returns the last non-zero coefficient of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**3 + 2*x**2 + 3*x, x).EC() 3 """ if hasattr(f.rep, 'coeffs'): return f.coeffs(order)[-1] else: # pragma: no cover raise OperationNotSupported(f, 'EC') def coeff_monomial(f, monom): """ Returns the coefficient of ``monom`` in ``f`` if there, else None. Examples ======== >>> from sympy import Poly, exp >>> from sympy.abc import x, y >>> p = Poly(24*x*y*exp(8) + 23*x, x, y) >>> p.coeff_monomial(x) 23 >>> p.coeff_monomial(y) 0 >>> p.coeff_monomial(x*y) 24*exp(8) Note that ``Expr.coeff()`` behaves differently, collecting terms if possible; the Poly must be converted to an Expr to use that method, however: >>> p.as_expr().coeff(x) 24*y*exp(8) + 23 >>> p.as_expr().coeff(y) 24*x*exp(8) >>> p.as_expr().coeff(x*y) 24*exp(8) See Also ======== nth: more efficient query using exponents of the monomial's generators """ return f.nth(*Monomial(monom, f.gens).exponents) def nth(f, *N): """ Returns the ``n``-th coefficient of ``f`` where ``N`` are the exponents of the generators in the term of interest. Examples ======== >>> from sympy import Poly, sqrt >>> from sympy.abc import x, y >>> Poly(x**3 + 2*x**2 + 3*x, x).nth(2) 2 >>> Poly(x**3 + 2*x*y**2 + y**2, x, y).nth(1, 2) 2 >>> Poly(4*sqrt(x)*y) Poly(4*y*(sqrt(x)), y, sqrt(x), domain='ZZ') >>> _.nth(1, 1) 4 See Also ======== coeff_monomial """ if hasattr(f.rep, 'nth'): if len(N) != len(f.gens): raise ValueError('exponent of each generator must be specified') result = f.rep.nth(*list(map(int, N))) else: # pragma: no cover raise OperationNotSupported(f, 'nth') return f.rep.dom.to_sympy(result) def coeff(f, x, n=1, right=False): # the semantics of coeff_monomial and Expr.coeff are different; # if someone is working with a Poly, they should be aware of the # differences and chose the method best suited for the query. # Alternatively, a pure-polys method could be written here but # at this time the ``right`` keyword would be ignored because Poly # doesn't work with non-commutatives. raise NotImplementedError( 'Either convert to Expr with `as_expr` method ' 'to use Expr\'s coeff method or else use the ' '`coeff_monomial` method of Polys.') def LM(f, order=None): """ Returns the leading monomial of ``f``. The Leading monomial signifies the monomial having the highest power of the principal generator in the expression f. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(4*x**2 + 2*x*y**2 + x*y + 3*y, x, y).LM() x**2*y**0 """ return Monomial(f.monoms(order)[0], f.gens) def EM(f, order=None): """ Returns the last non-zero monomial of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(4*x**2 + 2*x*y**2 + x*y + 3*y, x, y).EM() x**0*y**1 """ return Monomial(f.monoms(order)[-1], f.gens) def LT(f, order=None): """ Returns the leading term of ``f``. The Leading term signifies the term having the highest power of the principal generator in the expression f along with its coefficient. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(4*x**2 + 2*x*y**2 + x*y + 3*y, x, y).LT() (x**2*y**0, 4) """ monom, coeff = f.terms(order)[0] return Monomial(monom, f.gens), coeff def ET(f, order=None): """ Returns the last non-zero term of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(4*x**2 + 2*x*y**2 + x*y + 3*y, x, y).ET() (x**0*y**1, 3) """ monom, coeff = f.terms(order)[-1] return Monomial(monom, f.gens), coeff def max_norm(f): """ Returns maximum norm of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(-x**2 + 2*x - 3, x).max_norm() 3 """ if hasattr(f.rep, 'max_norm'): result = f.rep.max_norm() else: # pragma: no cover raise OperationNotSupported(f, 'max_norm') return f.rep.dom.to_sympy(result) def l1_norm(f): """ Returns l1 norm of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(-x**2 + 2*x - 3, x).l1_norm() 6 """ if hasattr(f.rep, 'l1_norm'): result = f.rep.l1_norm() else: # pragma: no cover raise OperationNotSupported(f, 'l1_norm') return f.rep.dom.to_sympy(result) def clear_denoms(self, convert=False): """ Clear denominators, but keep the ground domain. Examples ======== >>> from sympy import Poly, S, QQ >>> from sympy.abc import x >>> f = Poly(x/2 + S(1)/3, x, domain=QQ) >>> f.clear_denoms() (6, Poly(3*x + 2, x, domain='QQ')) >>> f.clear_denoms(convert=True) (6, Poly(3*x + 2, x, domain='ZZ')) """ f = self if not f.rep.dom.is_Field: return S.One, f dom = f.get_domain() if dom.has_assoc_Ring: dom = f.rep.dom.get_ring() if hasattr(f.rep, 'clear_denoms'): coeff, result = f.rep.clear_denoms() else: # pragma: no cover raise OperationNotSupported(f, 'clear_denoms') coeff, f = dom.to_sympy(coeff), f.per(result) if not convert or not dom.has_assoc_Ring: return coeff, f else: return coeff, f.to_ring() def rat_clear_denoms(self, g): """ Clear denominators in a rational function ``f/g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> f = Poly(x**2/y + 1, x) >>> g = Poly(x**3 + y, x) >>> p, q = f.rat_clear_denoms(g) >>> p Poly(x**2 + y, x, domain='ZZ[y]') >>> q Poly(y*x**3 + y**2, x, domain='ZZ[y]') """ f = self dom, per, f, g = f._unify(g) f = per(f) g = per(g) if not (dom.is_Field and dom.has_assoc_Ring): return f, g a, f = f.clear_denoms(convert=True) b, g = g.clear_denoms(convert=True) f = f.mul_ground(b) g = g.mul_ground(a) return f, g def integrate(self, *specs, **args): """ Computes indefinite integral of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**2 + 2*x + 1, x).integrate() Poly(1/3*x**3 + x**2 + x, x, domain='QQ') >>> Poly(x*y**2 + x, x, y).integrate((0, 1), (1, 0)) Poly(1/2*x**2*y**2 + 1/2*x**2, x, y, domain='QQ') """ f = self if args.get('auto', True) and f.rep.dom.is_Ring: f = f.to_field() if hasattr(f.rep, 'integrate'): if not specs: return f.per(f.rep.integrate(m=1)) rep = f.rep for spec in specs: if type(spec) is tuple: gen, m = spec else: gen, m = spec, 1 rep = rep.integrate(int(m), f._gen_to_level(gen)) return f.per(rep) else: # pragma: no cover raise OperationNotSupported(f, 'integrate') def diff(f, *specs, **kwargs): """ Computes partial derivative of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**2 + 2*x + 1, x).diff() Poly(2*x + 2, x, domain='ZZ') >>> Poly(x*y**2 + x, x, y).diff((0, 0), (1, 1)) Poly(2*x*y, x, y, domain='ZZ') """ if not kwargs.get('evaluate', True): return Derivative(f, *specs, **kwargs) if hasattr(f.rep, 'diff'): if not specs: return f.per(f.rep.diff(m=1)) rep = f.rep for spec in specs: if type(spec) is tuple: gen, m = spec else: gen, m = spec, 1 rep = rep.diff(int(m), f._gen_to_level(gen)) return f.per(rep) else: # pragma: no cover raise OperationNotSupported(f, 'diff') _eval_derivative = diff def eval(self, x, a=None, auto=True): """ Evaluate ``f`` at ``a`` in the given variable. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y, z >>> Poly(x**2 + 2*x + 3, x).eval(2) 11 >>> Poly(2*x*y + 3*x + y + 2, x, y).eval(x, 2) Poly(5*y + 8, y, domain='ZZ') >>> f = Poly(2*x*y + 3*x + y + 2*z, x, y, z) >>> f.eval({x: 2}) Poly(5*y + 2*z + 6, y, z, domain='ZZ') >>> f.eval({x: 2, y: 5}) Poly(2*z + 31, z, domain='ZZ') >>> f.eval({x: 2, y: 5, z: 7}) 45 >>> f.eval((2, 5)) Poly(2*z + 31, z, domain='ZZ') >>> f(2, 5) Poly(2*z + 31, z, domain='ZZ') """ f = self if a is None: if isinstance(x, dict): mapping = x for gen, value in mapping.items(): f = f.eval(gen, value) return f elif isinstance(x, (tuple, list)): values = x if len(values) > len(f.gens): raise ValueError("too many values provided") for gen, value in zip(f.gens, values): f = f.eval(gen, value) return f else: j, a = 0, x else: j = f._gen_to_level(x) if not hasattr(f.rep, 'eval'): # pragma: no cover raise OperationNotSupported(f, 'eval') try: result = f.rep.eval(a, j) except CoercionFailed: if not auto: raise DomainError("can't evaluate at %s in %s" % (a, f.rep.dom)) else: a_domain, [a] = construct_domain([a]) new_domain = f.get_domain().unify_with_symbols(a_domain, f.gens) f = f.set_domain(new_domain) a = new_domain.convert(a, a_domain) result = f.rep.eval(a, j) return f.per(result, remove=j) def __call__(f, *values): """ Evaluate ``f`` at the give values. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y, z >>> f = Poly(2*x*y + 3*x + y + 2*z, x, y, z) >>> f(2) Poly(5*y + 2*z + 6, y, z, domain='ZZ') >>> f(2, 5) Poly(2*z + 31, z, domain='ZZ') >>> f(2, 5, 7) 45 """ return f.eval(values) def half_gcdex(f, g, auto=True): """ Half extended Euclidean algorithm of ``f`` and ``g``. Returns ``(s, h)`` such that ``h = gcd(f, g)`` and ``s*f = h (mod g)``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> f = x**4 - 2*x**3 - 6*x**2 + 12*x + 15 >>> g = x**3 + x**2 - 4*x - 4 >>> Poly(f).half_gcdex(Poly(g)) (Poly(-1/5*x + 3/5, x, domain='QQ'), Poly(x + 1, x, domain='QQ')) """ dom, per, F, G = f._unify(g) if auto and dom.is_Ring: F, G = F.to_field(), G.to_field() if hasattr(f.rep, 'half_gcdex'): s, h = F.half_gcdex(G) else: # pragma: no cover raise OperationNotSupported(f, 'half_gcdex') return per(s), per(h) def gcdex(f, g, auto=True): """ Extended Euclidean algorithm of ``f`` and ``g``. Returns ``(s, t, h)`` such that ``h = gcd(f, g)`` and ``s*f + t*g = h``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> f = x**4 - 2*x**3 - 6*x**2 + 12*x + 15 >>> g = x**3 + x**2 - 4*x - 4 >>> Poly(f).gcdex(Poly(g)) (Poly(-1/5*x + 3/5, x, domain='QQ'), Poly(1/5*x**2 - 6/5*x + 2, x, domain='QQ'), Poly(x + 1, x, domain='QQ')) """ dom, per, F, G = f._unify(g) if auto and dom.is_Ring: F, G = F.to_field(), G.to_field() if hasattr(f.rep, 'gcdex'): s, t, h = F.gcdex(G) else: # pragma: no cover raise OperationNotSupported(f, 'gcdex') return per(s), per(t), per(h) def invert(f, g, auto=True): """ Invert ``f`` modulo ``g`` when possible. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 - 1, x).invert(Poly(2*x - 1, x)) Poly(-4/3, x, domain='QQ') >>> Poly(x**2 - 1, x).invert(Poly(x - 1, x)) Traceback (most recent call last): ... NotInvertible: zero divisor """ dom, per, F, G = f._unify(g) if auto and dom.is_Ring: F, G = F.to_field(), G.to_field() if hasattr(f.rep, 'invert'): result = F.invert(G) else: # pragma: no cover raise OperationNotSupported(f, 'invert') return per(result) def revert(f, n): """ Compute ``f**(-1)`` mod ``x**n``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(1, x).revert(2) Poly(1, x, domain='ZZ') >>> Poly(1 + x, x).revert(1) Poly(1, x, domain='ZZ') >>> Poly(x**2 - 1, x).revert(1) Traceback (most recent call last): ... NotReversible: only unity is reversible in a ring >>> Poly(1/x, x).revert(1) Traceback (most recent call last): ... PolynomialError: 1/x contains an element of the generators set """ if hasattr(f.rep, 'revert'): result = f.rep.revert(int(n)) else: # pragma: no cover raise OperationNotSupported(f, 'revert') return f.per(result) def subresultants(f, g): """ Computes the subresultant PRS of ``f`` and ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + 1, x).subresultants(Poly(x**2 - 1, x)) [Poly(x**2 + 1, x, domain='ZZ'), Poly(x**2 - 1, x, domain='ZZ'), Poly(-2, x, domain='ZZ')] """ _, per, F, G = f._unify(g) if hasattr(f.rep, 'subresultants'): result = F.subresultants(G) else: # pragma: no cover raise OperationNotSupported(f, 'subresultants') return list(map(per, result)) def resultant(f, g, includePRS=False): """ Computes the resultant of ``f`` and ``g`` via PRS. If includePRS=True, it includes the subresultant PRS in the result. Because the PRS is used to calculate the resultant, this is more efficient than calling :func:`subresultants` separately. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> f = Poly(x**2 + 1, x) >>> f.resultant(Poly(x**2 - 1, x)) 4 >>> f.resultant(Poly(x**2 - 1, x), includePRS=True) (4, [Poly(x**2 + 1, x, domain='ZZ'), Poly(x**2 - 1, x, domain='ZZ'), Poly(-2, x, domain='ZZ')]) """ _, per, F, G = f._unify(g) if hasattr(f.rep, 'resultant'): if includePRS: result, R = F.resultant(G, includePRS=includePRS) else: result = F.resultant(G) else: # pragma: no cover raise OperationNotSupported(f, 'resultant') if includePRS: return (per(result, remove=0), list(map(per, R))) return per(result, remove=0) def discriminant(f): """ Computes the discriminant of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + 2*x + 3, x).discriminant() -8 """ if hasattr(f.rep, 'discriminant'): result = f.rep.discriminant() else: # pragma: no cover raise OperationNotSupported(f, 'discriminant') return f.per(result, remove=0) def dispersionset(f, g=None): r"""Compute the *dispersion set* of two polynomials. For two polynomials `f(x)` and `g(x)` with `\deg f > 0` and `\deg g > 0` the dispersion set `\operatorname{J}(f, g)` is defined as: .. math:: \operatorname{J}(f, g) & := \{a \in \mathbb{N}_0 | \gcd(f(x), g(x+a)) \neq 1\} \\ & = \{a \in \mathbb{N}_0 | \deg \gcd(f(x), g(x+a)) \geq 1\} For a single polynomial one defines `\operatorname{J}(f) := \operatorname{J}(f, f)`. Examples ======== >>> from sympy import poly >>> from sympy.polys.dispersion import dispersion, dispersionset >>> from sympy.abc import x Dispersion set and dispersion of a simple polynomial: >>> fp = poly((x - 3)*(x + 3), x) >>> sorted(dispersionset(fp)) [0, 6] >>> dispersion(fp) 6 Note that the definition of the dispersion is not symmetric: >>> fp = poly(x**4 - 3*x**2 + 1, x) >>> gp = fp.shift(-3) >>> sorted(dispersionset(fp, gp)) [2, 3, 4] >>> dispersion(fp, gp) 4 >>> sorted(dispersionset(gp, fp)) [] >>> dispersion(gp, fp) -oo Computing the dispersion also works over field extensions: >>> from sympy import sqrt >>> fp = poly(x**2 + sqrt(5)*x - 1, x, domain='QQ<sqrt(5)>') >>> gp = poly(x**2 + (2 + sqrt(5))*x + sqrt(5), x, domain='QQ<sqrt(5)>') >>> sorted(dispersionset(fp, gp)) [2] >>> sorted(dispersionset(gp, fp)) [1, 4] We can even perform the computations for polynomials having symbolic coefficients: >>> from sympy.abc import a >>> fp = poly(4*x**4 + (4*a + 8)*x**3 + (a**2 + 6*a + 4)*x**2 + (a**2 + 2*a)*x, x) >>> sorted(dispersionset(fp)) [0, 1] See Also ======== dispersion References ========== 1. [ManWright94]_ 2. [Koepf98]_ 3. [Abramov71]_ 4. [Man93]_ """ from sympy.polys.dispersion import dispersionset return dispersionset(f, g) def dispersion(f, g=None): r"""Compute the *dispersion* of polynomials. For two polynomials `f(x)` and `g(x)` with `\deg f > 0` and `\deg g > 0` the dispersion `\operatorname{dis}(f, g)` is defined as: .. math:: \operatorname{dis}(f, g) & := \max\{ J(f,g) \cup \{0\} \} \\ & = \max\{ \{a \in \mathbb{N} | \gcd(f(x), g(x+a)) \neq 1\} \cup \{0\} \} and for a single polynomial `\operatorname{dis}(f) := \operatorname{dis}(f, f)`. Examples ======== >>> from sympy import poly >>> from sympy.polys.dispersion import dispersion, dispersionset >>> from sympy.abc import x Dispersion set and dispersion of a simple polynomial: >>> fp = poly((x - 3)*(x + 3), x) >>> sorted(dispersionset(fp)) [0, 6] >>> dispersion(fp) 6 Note that the definition of the dispersion is not symmetric: >>> fp = poly(x**4 - 3*x**2 + 1, x) >>> gp = fp.shift(-3) >>> sorted(dispersionset(fp, gp)) [2, 3, 4] >>> dispersion(fp, gp) 4 >>> sorted(dispersionset(gp, fp)) [] >>> dispersion(gp, fp) -oo Computing the dispersion also works over field extensions: >>> from sympy import sqrt >>> fp = poly(x**2 + sqrt(5)*x - 1, x, domain='QQ<sqrt(5)>') >>> gp = poly(x**2 + (2 + sqrt(5))*x + sqrt(5), x, domain='QQ<sqrt(5)>') >>> sorted(dispersionset(fp, gp)) [2] >>> sorted(dispersionset(gp, fp)) [1, 4] We can even perform the computations for polynomials having symbolic coefficients: >>> from sympy.abc import a >>> fp = poly(4*x**4 + (4*a + 8)*x**3 + (a**2 + 6*a + 4)*x**2 + (a**2 + 2*a)*x, x) >>> sorted(dispersionset(fp)) [0, 1] See Also ======== dispersionset References ========== 1. [ManWright94]_ 2. [Koepf98]_ 3. [Abramov71]_ 4. [Man93]_ """ from sympy.polys.dispersion import dispersion return dispersion(f, g) def cofactors(f, g): """ Returns the GCD of ``f`` and ``g`` and their cofactors. Returns polynomials ``(h, cff, cfg)`` such that ``h = gcd(f, g)``, and ``cff = quo(f, h)`` and ``cfg = quo(g, h)`` are, so called, cofactors of ``f`` and ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 - 1, x).cofactors(Poly(x**2 - 3*x + 2, x)) (Poly(x - 1, x, domain='ZZ'), Poly(x + 1, x, domain='ZZ'), Poly(x - 2, x, domain='ZZ')) """ _, per, F, G = f._unify(g) if hasattr(f.rep, 'cofactors'): h, cff, cfg = F.cofactors(G) else: # pragma: no cover raise OperationNotSupported(f, 'cofactors') return per(h), per(cff), per(cfg) def gcd(f, g): """ Returns the polynomial GCD of ``f`` and ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 - 1, x).gcd(Poly(x**2 - 3*x + 2, x)) Poly(x - 1, x, domain='ZZ') """ _, per, F, G = f._unify(g) if hasattr(f.rep, 'gcd'): result = F.gcd(G) else: # pragma: no cover raise OperationNotSupported(f, 'gcd') return per(result) def lcm(f, g): """ Returns polynomial LCM of ``f`` and ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 - 1, x).lcm(Poly(x**2 - 3*x + 2, x)) Poly(x**3 - 2*x**2 - x + 2, x, domain='ZZ') """ _, per, F, G = f._unify(g) if hasattr(f.rep, 'lcm'): result = F.lcm(G) else: # pragma: no cover raise OperationNotSupported(f, 'lcm') return per(result) def trunc(f, p): """ Reduce ``f`` modulo a constant ``p``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(2*x**3 + 3*x**2 + 5*x + 7, x).trunc(3) Poly(-x**3 - x + 1, x, domain='ZZ') """ p = f.rep.dom.convert(p) if hasattr(f.rep, 'trunc'): result = f.rep.trunc(p) else: # pragma: no cover raise OperationNotSupported(f, 'trunc') return f.per(result) def monic(self, auto=True): """ Divides all coefficients by ``LC(f)``. Examples ======== >>> from sympy import Poly, ZZ >>> from sympy.abc import x >>> Poly(3*x**2 + 6*x + 9, x, domain=ZZ).monic() Poly(x**2 + 2*x + 3, x, domain='QQ') >>> Poly(3*x**2 + 4*x + 2, x, domain=ZZ).monic() Poly(x**2 + 4/3*x + 2/3, x, domain='QQ') """ f = self if auto and f.rep.dom.is_Ring: f = f.to_field() if hasattr(f.rep, 'monic'): result = f.rep.monic() else: # pragma: no cover raise OperationNotSupported(f, 'monic') return f.per(result) def content(f): """ Returns the GCD of polynomial coefficients. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(6*x**2 + 8*x + 12, x).content() 2 """ if hasattr(f.rep, 'content'): result = f.rep.content() else: # pragma: no cover raise OperationNotSupported(f, 'content') return f.rep.dom.to_sympy(result) def primitive(f): """ Returns the content and a primitive form of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(2*x**2 + 8*x + 12, x).primitive() (2, Poly(x**2 + 4*x + 6, x, domain='ZZ')) """ if hasattr(f.rep, 'primitive'): cont, result = f.rep.primitive() else: # pragma: no cover raise OperationNotSupported(f, 'primitive') return f.rep.dom.to_sympy(cont), f.per(result) def compose(f, g): """ Computes the functional composition of ``f`` and ``g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + x, x).compose(Poly(x - 1, x)) Poly(x**2 - x, x, domain='ZZ') """ _, per, F, G = f._unify(g) if hasattr(f.rep, 'compose'): result = F.compose(G) else: # pragma: no cover raise OperationNotSupported(f, 'compose') return per(result) def decompose(f): """ Computes a functional decomposition of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**4 + 2*x**3 - x - 1, x, domain='ZZ').decompose() [Poly(x**2 - x - 1, x, domain='ZZ'), Poly(x**2 + x, x, domain='ZZ')] """ if hasattr(f.rep, 'decompose'): result = f.rep.decompose() else: # pragma: no cover raise OperationNotSupported(f, 'decompose') return list(map(f.per, result)) def shift(f, a): """ Efficiently compute Taylor shift ``f(x + a)``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 - 2*x + 1, x).shift(2) Poly(x**2 + 2*x + 1, x, domain='ZZ') """ if hasattr(f.rep, 'shift'): result = f.rep.shift(a) else: # pragma: no cover raise OperationNotSupported(f, 'shift') return f.per(result) def transform(f, p, q): """ Efficiently evaluate the functional transformation ``q**n * f(p/q)``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 - 2*x + 1, x).transform(Poly(x + 1, x), Poly(x - 1, x)) Poly(4, x, domain='ZZ') """ P, Q = p.unify(q) F, P = f.unify(P) F, Q = F.unify(Q) if hasattr(F.rep, 'transform'): result = F.rep.transform(P.rep, Q.rep) else: # pragma: no cover raise OperationNotSupported(F, 'transform') return F.per(result) def sturm(self, auto=True): """ Computes the Sturm sequence of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**3 - 2*x**2 + x - 3, x).sturm() [Poly(x**3 - 2*x**2 + x - 3, x, domain='QQ'), Poly(3*x**2 - 4*x + 1, x, domain='QQ'), Poly(2/9*x + 25/9, x, domain='QQ'), Poly(-2079/4, x, domain='QQ')] """ f = self if auto and f.rep.dom.is_Ring: f = f.to_field() if hasattr(f.rep, 'sturm'): result = f.rep.sturm() else: # pragma: no cover raise OperationNotSupported(f, 'sturm') return list(map(f.per, result)) def gff_list(f): """ Computes greatest factorial factorization of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> f = x**5 + 2*x**4 - x**3 - 2*x**2 >>> Poly(f).gff_list() [(Poly(x, x, domain='ZZ'), 1), (Poly(x + 2, x, domain='ZZ'), 4)] """ if hasattr(f.rep, 'gff_list'): result = f.rep.gff_list() else: # pragma: no cover raise OperationNotSupported(f, 'gff_list') return [(f.per(g), k) for g, k in result] def norm(f): """ Computes the product, ``Norm(f)``, of the conjugates of a polynomial ``f`` defined over a number field ``K``. Examples ======== >>> from sympy import Poly, sqrt >>> from sympy.abc import x >>> a, b = sqrt(2), sqrt(3) A polynomial over a quadratic extension. Two conjugates x - a and x + a. >>> f = Poly(x - a, x, extension=a) >>> f.norm() Poly(x**2 - 2, x, domain='QQ') A polynomial over a quartic extension. Four conjugates x - a, x - a, x + a and x + a. >>> f = Poly(x - a, x, extension=(a, b)) >>> f.norm() Poly(x**4 - 4*x**2 + 4, x, domain='QQ') """ if hasattr(f.rep, 'norm'): r = f.rep.norm() else: # pragma: no cover raise OperationNotSupported(f, 'norm') return f.per(r) def sqf_norm(f): """ Computes square-free norm of ``f``. Returns ``s``, ``f``, ``r``, such that ``g(x) = f(x-sa)`` and ``r(x) = Norm(g(x))`` is a square-free polynomial over ``K``, where ``a`` is the algebraic extension of the ground domain. Examples ======== >>> from sympy import Poly, sqrt >>> from sympy.abc import x >>> s, f, r = Poly(x**2 + 1, x, extension=[sqrt(3)]).sqf_norm() >>> s 1 >>> f Poly(x**2 - 2*sqrt(3)*x + 4, x, domain='QQ<sqrt(3)>') >>> r Poly(x**4 - 4*x**2 + 16, x, domain='QQ') """ if hasattr(f.rep, 'sqf_norm'): s, g, r = f.rep.sqf_norm() else: # pragma: no cover raise OperationNotSupported(f, 'sqf_norm') return s, f.per(g), f.per(r) def sqf_part(f): """ Computes square-free part of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**3 - 3*x - 2, x).sqf_part() Poly(x**2 - x - 2, x, domain='ZZ') """ if hasattr(f.rep, 'sqf_part'): result = f.rep.sqf_part() else: # pragma: no cover raise OperationNotSupported(f, 'sqf_part') return f.per(result) def sqf_list(f, all=False): """ Returns a list of square-free factors of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> f = 2*x**5 + 16*x**4 + 50*x**3 + 76*x**2 + 56*x + 16 >>> Poly(f).sqf_list() (2, [(Poly(x + 1, x, domain='ZZ'), 2), (Poly(x + 2, x, domain='ZZ'), 3)]) >>> Poly(f).sqf_list(all=True) (2, [(Poly(1, x, domain='ZZ'), 1), (Poly(x + 1, x, domain='ZZ'), 2), (Poly(x + 2, x, domain='ZZ'), 3)]) """ if hasattr(f.rep, 'sqf_list'): coeff, factors = f.rep.sqf_list(all) else: # pragma: no cover raise OperationNotSupported(f, 'sqf_list') return f.rep.dom.to_sympy(coeff), [(f.per(g), k) for g, k in factors] def sqf_list_include(f, all=False): """ Returns a list of square-free factors of ``f``. Examples ======== >>> from sympy import Poly, expand >>> from sympy.abc import x >>> f = expand(2*(x + 1)**3*x**4) >>> f 2*x**7 + 6*x**6 + 6*x**5 + 2*x**4 >>> Poly(f).sqf_list_include() [(Poly(2, x, domain='ZZ'), 1), (Poly(x + 1, x, domain='ZZ'), 3), (Poly(x, x, domain='ZZ'), 4)] >>> Poly(f).sqf_list_include(all=True) [(Poly(2, x, domain='ZZ'), 1), (Poly(1, x, domain='ZZ'), 2), (Poly(x + 1, x, domain='ZZ'), 3), (Poly(x, x, domain='ZZ'), 4)] """ if hasattr(f.rep, 'sqf_list_include'): factors = f.rep.sqf_list_include(all) else: # pragma: no cover raise OperationNotSupported(f, 'sqf_list_include') return [(f.per(g), k) for g, k in factors] def factor_list(f): """ Returns a list of irreducible factors of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> f = 2*x**5 + 2*x**4*y + 4*x**3 + 4*x**2*y + 2*x + 2*y >>> Poly(f).factor_list() (2, [(Poly(x + y, x, y, domain='ZZ'), 1), (Poly(x**2 + 1, x, y, domain='ZZ'), 2)]) """ if hasattr(f.rep, 'factor_list'): try: coeff, factors = f.rep.factor_list() except DomainError: return S.One, [(f, 1)] else: # pragma: no cover raise OperationNotSupported(f, 'factor_list') return f.rep.dom.to_sympy(coeff), [(f.per(g), k) for g, k in factors] def factor_list_include(f): """ Returns a list of irreducible factors of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> f = 2*x**5 + 2*x**4*y + 4*x**3 + 4*x**2*y + 2*x + 2*y >>> Poly(f).factor_list_include() [(Poly(2*x + 2*y, x, y, domain='ZZ'), 1), (Poly(x**2 + 1, x, y, domain='ZZ'), 2)] """ if hasattr(f.rep, 'factor_list_include'): try: factors = f.rep.factor_list_include() except DomainError: return [(f, 1)] else: # pragma: no cover raise OperationNotSupported(f, 'factor_list_include') return [(f.per(g), k) for g, k in factors] def intervals(f, all=False, eps=None, inf=None, sup=None, fast=False, sqf=False): """ Compute isolating intervals for roots of ``f``. For real roots the Vincent-Akritas-Strzebonski (VAS) continued fractions method is used. References ========== .. [#] Alkiviadis G. Akritas and Adam W. Strzebonski: A Comparative Study of Two Real Root Isolation Methods . Nonlinear Analysis: Modelling and Control, Vol. 10, No. 4, 297-304, 2005. .. [#] Alkiviadis G. Akritas, Adam W. Strzebonski and Panagiotis S. Vigklas: Improving the Performance of the Continued Fractions Method Using new Bounds of Positive Roots. Nonlinear Analysis: Modelling and Control, Vol. 13, No. 3, 265-279, 2008. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 - 3, x).intervals() [((-2, -1), 1), ((1, 2), 1)] >>> Poly(x**2 - 3, x).intervals(eps=1e-2) [((-26/15, -19/11), 1), ((19/11, 26/15), 1)] """ if eps is not None: eps = QQ.convert(eps) if eps <= 0: raise ValueError("'eps' must be a positive rational") if inf is not None: inf = QQ.convert(inf) if sup is not None: sup = QQ.convert(sup) if hasattr(f.rep, 'intervals'): result = f.rep.intervals( all=all, eps=eps, inf=inf, sup=sup, fast=fast, sqf=sqf) else: # pragma: no cover raise OperationNotSupported(f, 'intervals') if sqf: def _real(interval): s, t = interval return (QQ.to_sympy(s), QQ.to_sympy(t)) if not all: return list(map(_real, result)) def _complex(rectangle): (u, v), (s, t) = rectangle return (QQ.to_sympy(u) + I*QQ.to_sympy(v), QQ.to_sympy(s) + I*QQ.to_sympy(t)) real_part, complex_part = result return list(map(_real, real_part)), list(map(_complex, complex_part)) else: def _real(interval): (s, t), k = interval return ((QQ.to_sympy(s), QQ.to_sympy(t)), k) if not all: return list(map(_real, result)) def _complex(rectangle): ((u, v), (s, t)), k = rectangle return ((QQ.to_sympy(u) + I*QQ.to_sympy(v), QQ.to_sympy(s) + I*QQ.to_sympy(t)), k) real_part, complex_part = result return list(map(_real, real_part)), list(map(_complex, complex_part)) def refine_root(f, s, t, eps=None, steps=None, fast=False, check_sqf=False): """ Refine an isolating interval of a root to the given precision. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 - 3, x).refine_root(1, 2, eps=1e-2) (19/11, 26/15) """ if check_sqf and not f.is_sqf: raise PolynomialError("only square-free polynomials supported") s, t = QQ.convert(s), QQ.convert(t) if eps is not None: eps = QQ.convert(eps) if eps <= 0: raise ValueError("'eps' must be a positive rational") if steps is not None: steps = int(steps) elif eps is None: steps = 1 if hasattr(f.rep, 'refine_root'): S, T = f.rep.refine_root(s, t, eps=eps, steps=steps, fast=fast) else: # pragma: no cover raise OperationNotSupported(f, 'refine_root') return QQ.to_sympy(S), QQ.to_sympy(T) def count_roots(f, inf=None, sup=None): """ Return the number of roots of ``f`` in ``[inf, sup]`` interval. Examples ======== >>> from sympy import Poly, I >>> from sympy.abc import x >>> Poly(x**4 - 4, x).count_roots(-3, 3) 2 >>> Poly(x**4 - 4, x).count_roots(0, 1 + 3*I) 1 """ inf_real, sup_real = True, True if inf is not None: inf = sympify(inf) if inf is S.NegativeInfinity: inf = None else: re, im = inf.as_real_imag() if not im: inf = QQ.convert(inf) else: inf, inf_real = list(map(QQ.convert, (re, im))), False if sup is not None: sup = sympify(sup) if sup is S.Infinity: sup = None else: re, im = sup.as_real_imag() if not im: sup = QQ.convert(sup) else: sup, sup_real = list(map(QQ.convert, (re, im))), False if inf_real and sup_real: if hasattr(f.rep, 'count_real_roots'): count = f.rep.count_real_roots(inf=inf, sup=sup) else: # pragma: no cover raise OperationNotSupported(f, 'count_real_roots') else: if inf_real and inf is not None: inf = (inf, QQ.zero) if sup_real and sup is not None: sup = (sup, QQ.zero) if hasattr(f.rep, 'count_complex_roots'): count = f.rep.count_complex_roots(inf=inf, sup=sup) else: # pragma: no cover raise OperationNotSupported(f, 'count_complex_roots') return Integer(count) def root(f, index, radicals=True): """ Get an indexed root of a polynomial. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> f = Poly(2*x**3 - 7*x**2 + 4*x + 4) >>> f.root(0) -1/2 >>> f.root(1) 2 >>> f.root(2) 2 >>> f.root(3) Traceback (most recent call last): ... IndexError: root index out of [-3, 2] range, got 3 >>> Poly(x**5 + x + 1).root(0) CRootOf(x**3 - x**2 + 1, 0) """ return sympy.polys.rootoftools.rootof(f, index, radicals=radicals) def real_roots(f, multiple=True, radicals=True): """ Return a list of real roots with multiplicities. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(2*x**3 - 7*x**2 + 4*x + 4).real_roots() [-1/2, 2, 2] >>> Poly(x**3 + x + 1).real_roots() [CRootOf(x**3 + x + 1, 0)] """ reals = sympy.polys.rootoftools.CRootOf.real_roots(f, radicals=radicals) if multiple: return reals else: return group(reals, multiple=False) def all_roots(f, multiple=True, radicals=True): """ Return a list of real and complex roots with multiplicities. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(2*x**3 - 7*x**2 + 4*x + 4).all_roots() [-1/2, 2, 2] >>> Poly(x**3 + x + 1).all_roots() [CRootOf(x**3 + x + 1, 0), CRootOf(x**3 + x + 1, 1), CRootOf(x**3 + x + 1, 2)] """ roots = sympy.polys.rootoftools.CRootOf.all_roots(f, radicals=radicals) if multiple: return roots else: return group(roots, multiple=False) def nroots(f, n=15, maxsteps=50, cleanup=True): """ Compute numerical approximations of roots of ``f``. Parameters ========== n ... the number of digits to calculate maxsteps ... the maximum number of iterations to do If the accuracy `n` cannot be reached in `maxsteps`, it will raise an exception. You need to rerun with higher maxsteps. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 - 3).nroots(n=15) [-1.73205080756888, 1.73205080756888] >>> Poly(x**2 - 3).nroots(n=30) [-1.73205080756887729352744634151, 1.73205080756887729352744634151] """ from sympy.functions.elementary.complexes import sign if f.is_multivariate: raise MultivariatePolynomialError( "can't compute numerical roots of %s" % f) if f.degree() <= 0: return [] # For integer and rational coefficients, convert them to integers only # (for accuracy). Otherwise just try to convert the coefficients to # mpmath.mpc and raise an exception if the conversion fails. if f.rep.dom is ZZ: coeffs = [int(coeff) for coeff in f.all_coeffs()] elif f.rep.dom is QQ: denoms = [coeff.q for coeff in f.all_coeffs()] from sympy.core.numbers import ilcm fac = ilcm(*denoms) coeffs = [int(coeff*fac) for coeff in f.all_coeffs()] else: coeffs = [coeff.evalf(n=n).as_real_imag() for coeff in f.all_coeffs()] try: coeffs = [mpmath.mpc(*coeff) for coeff in coeffs] except TypeError: raise DomainError("Numerical domain expected, got %s" % \ f.rep.dom) dps = mpmath.mp.dps mpmath.mp.dps = n try: # We need to add extra precision to guard against losing accuracy. # 10 times the degree of the polynomial seems to work well. roots = mpmath.polyroots(coeffs, maxsteps=maxsteps, cleanup=cleanup, error=False, extraprec=f.degree()*10) # Mpmath puts real roots first, then complex ones (as does all_roots) # so we make sure this convention holds here, too. roots = list(map(sympify, sorted(roots, key=lambda r: (1 if r.imag else 0, r.real, abs(r.imag), sign(r.imag))))) except NoConvergence: raise NoConvergence( 'convergence to root failed; try n < %s or maxsteps > %s' % ( n, maxsteps)) finally: mpmath.mp.dps = dps return roots def ground_roots(f): """ Compute roots of ``f`` by factorization in the ground domain. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**6 - 4*x**4 + 4*x**3 - x**2).ground_roots() {0: 2, 1: 2} """ if f.is_multivariate: raise MultivariatePolynomialError( "can't compute ground roots of %s" % f) roots = {} for factor, k in f.factor_list()[1]: if factor.is_linear: a, b = factor.all_coeffs() roots[-b/a] = k return roots def nth_power_roots_poly(f, n): """ Construct a polynomial with n-th powers of roots of ``f``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> f = Poly(x**4 - x**2 + 1) >>> f.nth_power_roots_poly(2) Poly(x**4 - 2*x**3 + 3*x**2 - 2*x + 1, x, domain='ZZ') >>> f.nth_power_roots_poly(3) Poly(x**4 + 2*x**2 + 1, x, domain='ZZ') >>> f.nth_power_roots_poly(4) Poly(x**4 + 2*x**3 + 3*x**2 + 2*x + 1, x, domain='ZZ') >>> f.nth_power_roots_poly(12) Poly(x**4 - 4*x**3 + 6*x**2 - 4*x + 1, x, domain='ZZ') """ if f.is_multivariate: raise MultivariatePolynomialError( "must be a univariate polynomial") N = sympify(n) if N.is_Integer and N >= 1: n = int(N) else: raise ValueError("'n' must an integer and n >= 1, got %s" % n) x = f.gen t = Dummy('t') r = f.resultant(f.__class__.from_expr(x**n - t, x, t)) return r.replace(t, x) def cancel(f, g, include=False): """ Cancel common factors in a rational function ``f/g``. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(2*x**2 - 2, x).cancel(Poly(x**2 - 2*x + 1, x)) (1, Poly(2*x + 2, x, domain='ZZ'), Poly(x - 1, x, domain='ZZ')) >>> Poly(2*x**2 - 2, x).cancel(Poly(x**2 - 2*x + 1, x), include=True) (Poly(2*x + 2, x, domain='ZZ'), Poly(x - 1, x, domain='ZZ')) """ dom, per, F, G = f._unify(g) if hasattr(F, 'cancel'): result = F.cancel(G, include=include) else: # pragma: no cover raise OperationNotSupported(f, 'cancel') if not include: if dom.has_assoc_Ring: dom = dom.get_ring() cp, cq, p, q = result cp = dom.to_sympy(cp) cq = dom.to_sympy(cq) return cp/cq, per(p), per(q) else: return tuple(map(per, result)) @property def is_zero(f): """ Returns ``True`` if ``f`` is a zero polynomial. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(0, x).is_zero True >>> Poly(1, x).is_zero False """ return f.rep.is_zero @property def is_one(f): """ Returns ``True`` if ``f`` is a unit polynomial. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(0, x).is_one False >>> Poly(1, x).is_one True """ return f.rep.is_one @property def is_sqf(f): """ Returns ``True`` if ``f`` is a square-free polynomial. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 - 2*x + 1, x).is_sqf False >>> Poly(x**2 - 1, x).is_sqf True """ return f.rep.is_sqf @property def is_monic(f): """ Returns ``True`` if the leading coefficient of ``f`` is one. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x + 2, x).is_monic True >>> Poly(2*x + 2, x).is_monic False """ return f.rep.is_monic @property def is_primitive(f): """ Returns ``True`` if GCD of the coefficients of ``f`` is one. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(2*x**2 + 6*x + 12, x).is_primitive False >>> Poly(x**2 + 3*x + 6, x).is_primitive True """ return f.rep.is_primitive @property def is_ground(f): """ Returns ``True`` if ``f`` is an element of the ground domain. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x, x).is_ground False >>> Poly(2, x).is_ground True >>> Poly(y, x).is_ground True """ return f.rep.is_ground @property def is_linear(f): """ Returns ``True`` if ``f`` is linear in all its variables. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x + y + 2, x, y).is_linear True >>> Poly(x*y + 2, x, y).is_linear False """ return f.rep.is_linear @property def is_quadratic(f): """ Returns ``True`` if ``f`` is quadratic in all its variables. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x*y + 2, x, y).is_quadratic True >>> Poly(x*y**2 + 2, x, y).is_quadratic False """ return f.rep.is_quadratic @property def is_monomial(f): """ Returns ``True`` if ``f`` is zero or has only one term. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(3*x**2, x).is_monomial True >>> Poly(3*x**2 + 1, x).is_monomial False """ return f.rep.is_monomial @property def is_homogeneous(f): """ Returns ``True`` if ``f`` is a homogeneous polynomial. A homogeneous polynomial is a polynomial whose all monomials with non-zero coefficients have the same total degree. If you want not only to check if a polynomial is homogeneous but also compute its homogeneous order, then use :func:`Poly.homogeneous_order`. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**2 + x*y, x, y).is_homogeneous True >>> Poly(x**3 + x*y, x, y).is_homogeneous False """ return f.rep.is_homogeneous @property def is_irreducible(f): """ Returns ``True`` if ``f`` has no factors over its domain. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> Poly(x**2 + x + 1, x, modulus=2).is_irreducible True >>> Poly(x**2 + 1, x, modulus=2).is_irreducible False """ return f.rep.is_irreducible @property def is_univariate(f): """ Returns ``True`` if ``f`` is a univariate polynomial. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**2 + x + 1, x).is_univariate True >>> Poly(x*y**2 + x*y + 1, x, y).is_univariate False >>> Poly(x*y**2 + x*y + 1, x).is_univariate True >>> Poly(x**2 + x + 1, x, y).is_univariate False """ return len(f.gens) == 1 @property def is_multivariate(f): """ Returns ``True`` if ``f`` is a multivariate polynomial. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x, y >>> Poly(x**2 + x + 1, x).is_multivariate False >>> Poly(x*y**2 + x*y + 1, x, y).is_multivariate True >>> Poly(x*y**2 + x*y + 1, x).is_multivariate False >>> Poly(x**2 + x + 1, x, y).is_multivariate True """ return len(f.gens) != 1 @property def is_cyclotomic(f): """ Returns ``True`` if ``f`` is a cyclotomic polnomial. Examples ======== >>> from sympy import Poly >>> from sympy.abc import x >>> f = x**16 + x**14 - x**10 + x**8 - x**6 + x**2 + 1 >>> Poly(f).is_cyclotomic False >>> g = x**16 + x**14 - x**10 - x**8 - x**6 + x**2 + 1 >>> Poly(g).is_cyclotomic True """ return f.rep.is_cyclotomic def __abs__(f): return f.abs() def __neg__(f): return f.neg() @_sympifyit('g', NotImplemented) def __add__(f, g): if not g.is_Poly: try: g = f.__class__(g, *f.gens) except PolynomialError: return f.as_expr() + g return f.add(g) @_sympifyit('g', NotImplemented) def __radd__(f, g): if not g.is_Poly: try: g = f.__class__(g, *f.gens) except PolynomialError: return g + f.as_expr() return g.add(f) @_sympifyit('g', NotImplemented) def __sub__(f, g): if not g.is_Poly: try: g = f.__class__(g, *f.gens) except PolynomialError: return f.as_expr() - g return f.sub(g) @_sympifyit('g', NotImplemented) def __rsub__(f, g): if not g.is_Poly: try: g = f.__class__(g, *f.gens) except PolynomialError: return g - f.as_expr() return g.sub(f) @_sympifyit('g', NotImplemented) def __mul__(f, g): if not g.is_Poly: try: g = f.__class__(g, *f.gens) except PolynomialError: return f.as_expr()*g return f.mul(g) @_sympifyit('g', NotImplemented) def __rmul__(f, g): if not g.is_Poly: try: g = f.__class__(g, *f.gens) except PolynomialError: return g*f.as_expr() return g.mul(f) @_sympifyit('n', NotImplemented) def __pow__(f, n): if n.is_Integer and n >= 0: return f.pow(n) else: return f.as_expr()**n @_sympifyit('g', NotImplemented) def __divmod__(f, g): if not g.is_Poly: g = f.__class__(g, *f.gens) return f.div(g) @_sympifyit('g', NotImplemented) def __rdivmod__(f, g): if not g.is_Poly: g = f.__class__(g, *f.gens) return g.div(f) @_sympifyit('g', NotImplemented) def __mod__(f, g): if not g.is_Poly: g = f.__class__(g, *f.gens) return f.rem(g) @_sympifyit('g', NotImplemented) def __rmod__(f, g): if not g.is_Poly: g = f.__class__(g, *f.gens) return g.rem(f) @_sympifyit('g', NotImplemented) def __floordiv__(f, g): if not g.is_Poly: g = f.__class__(g, *f.gens) return f.quo(g) @_sympifyit('g', NotImplemented) def __rfloordiv__(f, g): if not g.is_Poly: g = f.__class__(g, *f.gens) return g.quo(f) @_sympifyit('g', NotImplemented) def __div__(f, g): return f.as_expr()/g.as_expr() @_sympifyit('g', NotImplemented) def __rdiv__(f, g): return g.as_expr()/f.as_expr() __truediv__ = __div__ __rtruediv__ = __rdiv__ @_sympifyit('other', NotImplemented) def __eq__(self, other): f, g = self, other if not g.is_Poly: try: g = f.__class__(g, f.gens, domain=f.get_domain()) except (PolynomialError, DomainError, CoercionFailed): return False if f.gens != g.gens: return False if f.rep.dom != g.rep.dom: try: dom = f.rep.dom.unify(g.rep.dom, f.gens) except UnificationFailed: return False f = f.set_domain(dom) g = g.set_domain(dom) return f.rep == g.rep @_sympifyit('g', NotImplemented) def __ne__(f, g): return not f == g def __nonzero__(f): return not f.is_zero __bool__ = __nonzero__ def eq(f, g, strict=False): if not strict: return f == g else: return f._strict_eq(sympify(g)) def ne(f, g, strict=False): return not f.eq(g, strict=strict) def _strict_eq(f, g): return isinstance(g, f.__class__) and f.gens == g.gens and f.rep.eq(g.rep, strict=True) @public class PurePoly(Poly): """Class for representing pure polynomials. """ def _hashable_content(self): """Allow SymPy to hash Poly instances. """ return (self.rep,) def __hash__(self): return super(PurePoly, self).__hash__() @property def free_symbols(self): """ Free symbols of a polynomial. Examples ======== >>> from sympy import PurePoly >>> from sympy.abc import x, y >>> PurePoly(x**2 + 1).free_symbols set() >>> PurePoly(x**2 + y).free_symbols set() >>> PurePoly(x**2 + y, x).free_symbols {y} """ return self.free_symbols_in_domain @_sympifyit('other', NotImplemented) def __eq__(self, other): f, g = self, other if not g.is_Poly: try: g = f.__class__(g, f.gens, domain=f.get_domain()) except (PolynomialError, DomainError, CoercionFailed): return False if len(f.gens) != len(g.gens): return False if f.rep.dom != g.rep.dom: try: dom = f.rep.dom.unify(g.rep.dom, f.gens) except UnificationFailed: return False f = f.set_domain(dom) g = g.set_domain(dom) return f.rep == g.rep def _strict_eq(f, g): return isinstance(g, f.__class__) and f.rep.eq(g.rep, strict=True) def _unify(f, g): g = sympify(g) if not g.is_Poly: try: return f.rep.dom, f.per, f.rep, f.rep.per(f.rep.dom.from_sympy(g)) except CoercionFailed: raise UnificationFailed("can't unify %s with %s" % (f, g)) if len(f.gens) != len(g.gens): raise UnificationFailed("can't unify %s with %s" % (f, g)) if not (isinstance(f.rep, DMP) and isinstance(g.rep, DMP)): raise UnificationFailed("can't unify %s with %s" % (f, g)) cls = f.__class__ gens = f.gens dom = f.rep.dom.unify(g.rep.dom, gens) F = f.rep.convert(dom) G = g.rep.convert(dom) def per(rep, dom=dom, gens=gens, remove=None): if remove is not None: gens = gens[:remove] + gens[remove + 1:] if not gens: return dom.to_sympy(rep) return cls.new(rep, *gens) return dom, per, F, G @public def poly_from_expr(expr, *gens, **args): """Construct a polynomial from an expression. """ opt = options.build_options(gens, args) return _poly_from_expr(expr, opt) def _poly_from_expr(expr, opt): """Construct a polynomial from an expression. """ orig, expr = expr, sympify(expr) if not isinstance(expr, Basic): raise PolificationFailed(opt, orig, expr) elif expr.is_Poly: poly = expr.__class__._from_poly(expr, opt) opt.gens = poly.gens opt.domain = poly.domain if opt.polys is None: opt.polys = True return poly, opt elif opt.expand: expr = expr.expand() rep, opt = _dict_from_expr(expr, opt) if not opt.gens: raise PolificationFailed(opt, orig, expr) monoms, coeffs = list(zip(*list(rep.items()))) domain = opt.domain if domain is None: opt.domain, coeffs = construct_domain(coeffs, opt=opt) else: coeffs = list(map(domain.from_sympy, coeffs)) rep = dict(list(zip(monoms, coeffs))) poly = Poly._from_dict(rep, opt) if opt.polys is None: opt.polys = False return poly, opt @public def parallel_poly_from_expr(exprs, *gens, **args): """Construct polynomials from expressions. """ opt = options.build_options(gens, args) return _parallel_poly_from_expr(exprs, opt) def _parallel_poly_from_expr(exprs, opt): """Construct polynomials from expressions. """ from sympy.functions.elementary.piecewise import Piecewise if len(exprs) == 2: f, g = exprs if isinstance(f, Poly) and isinstance(g, Poly): f = f.__class__._from_poly(f, opt) g = g.__class__._from_poly(g, opt) f, g = f.unify(g) opt.gens = f.gens opt.domain = f.domain if opt.polys is None: opt.polys = True return [f, g], opt origs, exprs = list(exprs), [] _exprs, _polys = [], [] failed = False for i, expr in enumerate(origs): expr = sympify(expr) if isinstance(expr, Basic): if expr.is_Poly: _polys.append(i) else: _exprs.append(i) if opt.expand: expr = expr.expand() else: failed = True exprs.append(expr) if failed: raise PolificationFailed(opt, origs, exprs, True) if _polys: # XXX: this is a temporary solution for i in _polys: exprs[i] = exprs[i].as_expr() reps, opt = _parallel_dict_from_expr(exprs, opt) if not opt.gens: raise PolificationFailed(opt, origs, exprs, True) for k in opt.gens: if isinstance(k, Piecewise): raise PolynomialError("Piecewise generators do not make sense") coeffs_list, lengths = [], [] all_monoms = [] all_coeffs = [] for rep in reps: monoms, coeffs = list(zip(*list(rep.items()))) coeffs_list.extend(coeffs) all_monoms.append(monoms) lengths.append(len(coeffs)) domain = opt.domain if domain is None: opt.domain, coeffs_list = construct_domain(coeffs_list, opt=opt) else: coeffs_list = list(map(domain.from_sympy, coeffs_list)) for k in lengths: all_coeffs.append(coeffs_list[:k]) coeffs_list = coeffs_list[k:] polys = [] for monoms, coeffs in zip(all_monoms, all_coeffs): rep = dict(list(zip(monoms, coeffs))) poly = Poly._from_dict(rep, opt) polys.append(poly) if opt.polys is None: opt.polys = bool(_polys) return polys, opt def _update_args(args, key, value): """Add a new ``(key, value)`` pair to arguments ``dict``. """ args = dict(args) if key not in args: args[key] = value return args @public def degree(f, gen=0): """ Return the degree of ``f`` in the given variable. The degree of 0 is negative infinity. Examples ======== >>> from sympy import degree >>> from sympy.abc import x, y >>> degree(x**2 + y*x + 1, gen=x) 2 >>> degree(x**2 + y*x + 1, gen=y) 1 >>> degree(0, x) -oo See also ======== total_degree degree_list """ f = sympify(f, strict=True) gen_is_Num = sympify(gen, strict=True).is_Number if f.is_Poly: p = f isNum = p.as_expr().is_Number else: isNum = f.is_Number if not isNum: if gen_is_Num: p, _ = poly_from_expr(f) else: p, _ = poly_from_expr(f, gen) if isNum: return S.Zero if f else S.NegativeInfinity if not gen_is_Num: if f.is_Poly and gen not in p.gens: # try recast without explicit gens p, _ = poly_from_expr(f.as_expr()) if gen not in p.gens: return S.Zero elif not f.is_Poly and len(f.free_symbols) > 1: raise TypeError(filldedent(''' A symbolic generator of interest is required for a multivariate expression like func = %s, e.g. degree(func, gen = %s) instead of degree(func, gen = %s). ''' % (f, next(ordered(f.free_symbols)), gen))) return Integer(p.degree(gen)) @public def total_degree(f, *gens): """ Return the total_degree of ``f`` in the given variables. Examples ======== >>> from sympy import total_degree, Poly >>> from sympy.abc import x, y, z >>> total_degree(1) 0 >>> total_degree(x + x*y) 2 >>> total_degree(x + x*y, x) 1 If the expression is a Poly and no variables are given then the generators of the Poly will be used: >>> p = Poly(x + x*y, y) >>> total_degree(p) 1 To deal with the underlying expression of the Poly, convert it to an Expr: >>> total_degree(p.as_expr()) 2 This is done automatically if any variables are given: >>> total_degree(p, x) 1 See also ======== degree """ p = sympify(f) if p.is_Poly: p = p.as_expr() if p.is_Number: rv = 0 else: if f.is_Poly: gens = gens or f.gens rv = Poly(p, gens).total_degree() return Integer(rv) @public def degree_list(f, *gens, **args): """ Return a list of degrees of ``f`` in all variables. Examples ======== >>> from sympy import degree_list >>> from sympy.abc import x, y >>> degree_list(x**2 + y*x + 1) (2, 1) """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('degree_list', 1, exc) degrees = F.degree_list() return tuple(map(Integer, degrees)) @public def LC(f, *gens, **args): """ Return the leading coefficient of ``f``. Examples ======== >>> from sympy import LC >>> from sympy.abc import x, y >>> LC(4*x**2 + 2*x*y**2 + x*y + 3*y) 4 """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('LC', 1, exc) return F.LC(order=opt.order) @public def LM(f, *gens, **args): """ Return the leading monomial of ``f``. Examples ======== >>> from sympy import LM >>> from sympy.abc import x, y >>> LM(4*x**2 + 2*x*y**2 + x*y + 3*y) x**2 """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('LM', 1, exc) monom = F.LM(order=opt.order) return monom.as_expr() @public def LT(f, *gens, **args): """ Return the leading term of ``f``. Examples ======== >>> from sympy import LT >>> from sympy.abc import x, y >>> LT(4*x**2 + 2*x*y**2 + x*y + 3*y) 4*x**2 """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('LT', 1, exc) monom, coeff = F.LT(order=opt.order) return coeff*monom.as_expr() @public def pdiv(f, g, *gens, **args): """ Compute polynomial pseudo-division of ``f`` and ``g``. Examples ======== >>> from sympy import pdiv >>> from sympy.abc import x >>> pdiv(x**2 + 1, 2*x - 4) (2*x + 4, 20) """ options.allowed_flags(args, ['polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: raise ComputationFailed('pdiv', 2, exc) q, r = F.pdiv(G) if not opt.polys: return q.as_expr(), r.as_expr() else: return q, r @public def prem(f, g, *gens, **args): """ Compute polynomial pseudo-remainder of ``f`` and ``g``. Examples ======== >>> from sympy import prem >>> from sympy.abc import x >>> prem(x**2 + 1, 2*x - 4) 20 """ options.allowed_flags(args, ['polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: raise ComputationFailed('prem', 2, exc) r = F.prem(G) if not opt.polys: return r.as_expr() else: return r @public def pquo(f, g, *gens, **args): """ Compute polynomial pseudo-quotient of ``f`` and ``g``. Examples ======== >>> from sympy import pquo >>> from sympy.abc import x >>> pquo(x**2 + 1, 2*x - 4) 2*x + 4 >>> pquo(x**2 - 1, 2*x - 1) 2*x + 1 """ options.allowed_flags(args, ['polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: raise ComputationFailed('pquo', 2, exc) try: q = F.pquo(G) except ExactQuotientFailed: raise ExactQuotientFailed(f, g) if not opt.polys: return q.as_expr() else: return q @public def pexquo(f, g, *gens, **args): """ Compute polynomial exact pseudo-quotient of ``f`` and ``g``. Examples ======== >>> from sympy import pexquo >>> from sympy.abc import x >>> pexquo(x**2 - 1, 2*x - 2) 2*x + 2 >>> pexquo(x**2 + 1, 2*x - 4) Traceback (most recent call last): ... ExactQuotientFailed: 2*x - 4 does not divide x**2 + 1 """ options.allowed_flags(args, ['polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: raise ComputationFailed('pexquo', 2, exc) q = F.pexquo(G) if not opt.polys: return q.as_expr() else: return q @public def div(f, g, *gens, **args): """ Compute polynomial division of ``f`` and ``g``. Examples ======== >>> from sympy import div, ZZ, QQ >>> from sympy.abc import x >>> div(x**2 + 1, 2*x - 4, domain=ZZ) (0, x**2 + 1) >>> div(x**2 + 1, 2*x - 4, domain=QQ) (x/2 + 1, 5) """ options.allowed_flags(args, ['auto', 'polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: raise ComputationFailed('div', 2, exc) q, r = F.div(G, auto=opt.auto) if not opt.polys: return q.as_expr(), r.as_expr() else: return q, r @public def rem(f, g, *gens, **args): """ Compute polynomial remainder of ``f`` and ``g``. Examples ======== >>> from sympy import rem, ZZ, QQ >>> from sympy.abc import x >>> rem(x**2 + 1, 2*x - 4, domain=ZZ) x**2 + 1 >>> rem(x**2 + 1, 2*x - 4, domain=QQ) 5 """ options.allowed_flags(args, ['auto', 'polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: raise ComputationFailed('rem', 2, exc) r = F.rem(G, auto=opt.auto) if not opt.polys: return r.as_expr() else: return r @public def quo(f, g, *gens, **args): """ Compute polynomial quotient of ``f`` and ``g``. Examples ======== >>> from sympy import quo >>> from sympy.abc import x >>> quo(x**2 + 1, 2*x - 4) x/2 + 1 >>> quo(x**2 - 1, x - 1) x + 1 """ options.allowed_flags(args, ['auto', 'polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: raise ComputationFailed('quo', 2, exc) q = F.quo(G, auto=opt.auto) if not opt.polys: return q.as_expr() else: return q @public def exquo(f, g, *gens, **args): """ Compute polynomial exact quotient of ``f`` and ``g``. Examples ======== >>> from sympy import exquo >>> from sympy.abc import x >>> exquo(x**2 - 1, x - 1) x + 1 >>> exquo(x**2 + 1, 2*x - 4) Traceback (most recent call last): ... ExactQuotientFailed: 2*x - 4 does not divide x**2 + 1 """ options.allowed_flags(args, ['auto', 'polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: raise ComputationFailed('exquo', 2, exc) q = F.exquo(G, auto=opt.auto) if not opt.polys: return q.as_expr() else: return q @public def half_gcdex(f, g, *gens, **args): """ Half extended Euclidean algorithm of ``f`` and ``g``. Returns ``(s, h)`` such that ``h = gcd(f, g)`` and ``s*f = h (mod g)``. Examples ======== >>> from sympy import half_gcdex >>> from sympy.abc import x >>> half_gcdex(x**4 - 2*x**3 - 6*x**2 + 12*x + 15, x**3 + x**2 - 4*x - 4) (-x/5 + 3/5, x + 1) """ options.allowed_flags(args, ['auto', 'polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: domain, (a, b) = construct_domain(exc.exprs) try: s, h = domain.half_gcdex(a, b) except NotImplementedError: raise ComputationFailed('half_gcdex', 2, exc) else: return domain.to_sympy(s), domain.to_sympy(h) s, h = F.half_gcdex(G, auto=opt.auto) if not opt.polys: return s.as_expr(), h.as_expr() else: return s, h @public def gcdex(f, g, *gens, **args): """ Extended Euclidean algorithm of ``f`` and ``g``. Returns ``(s, t, h)`` such that ``h = gcd(f, g)`` and ``s*f + t*g = h``. Examples ======== >>> from sympy import gcdex >>> from sympy.abc import x >>> gcdex(x**4 - 2*x**3 - 6*x**2 + 12*x + 15, x**3 + x**2 - 4*x - 4) (-x/5 + 3/5, x**2/5 - 6*x/5 + 2, x + 1) """ options.allowed_flags(args, ['auto', 'polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: domain, (a, b) = construct_domain(exc.exprs) try: s, t, h = domain.gcdex(a, b) except NotImplementedError: raise ComputationFailed('gcdex', 2, exc) else: return domain.to_sympy(s), domain.to_sympy(t), domain.to_sympy(h) s, t, h = F.gcdex(G, auto=opt.auto) if not opt.polys: return s.as_expr(), t.as_expr(), h.as_expr() else: return s, t, h @public def invert(f, g, *gens, **args): """ Invert ``f`` modulo ``g`` when possible. Examples ======== >>> from sympy import invert, S >>> from sympy.core.numbers import mod_inverse >>> from sympy.abc import x >>> invert(x**2 - 1, 2*x - 1) -4/3 >>> invert(x**2 - 1, x - 1) Traceback (most recent call last): ... NotInvertible: zero divisor For more efficient inversion of Rationals, use the ``mod_inverse`` function: >>> mod_inverse(3, 5) 2 >>> (S(2)/5).invert(S(7)/3) 5/2 See Also ======== sympy.core.numbers.mod_inverse """ options.allowed_flags(args, ['auto', 'polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: domain, (a, b) = construct_domain(exc.exprs) try: return domain.to_sympy(domain.invert(a, b)) except NotImplementedError: raise ComputationFailed('invert', 2, exc) h = F.invert(G, auto=opt.auto) if not opt.polys: return h.as_expr() else: return h @public def subresultants(f, g, *gens, **args): """ Compute subresultant PRS of ``f`` and ``g``. Examples ======== >>> from sympy import subresultants >>> from sympy.abc import x >>> subresultants(x**2 + 1, x**2 - 1) [x**2 + 1, x**2 - 1, -2] """ options.allowed_flags(args, ['polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: raise ComputationFailed('subresultants', 2, exc) result = F.subresultants(G) if not opt.polys: return [r.as_expr() for r in result] else: return result @public def resultant(f, g, *gens, **args): """ Compute resultant of ``f`` and ``g``. Examples ======== >>> from sympy import resultant >>> from sympy.abc import x >>> resultant(x**2 + 1, x**2 - 1) 4 """ includePRS = args.pop('includePRS', False) options.allowed_flags(args, ['polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: raise ComputationFailed('resultant', 2, exc) if includePRS: result, R = F.resultant(G, includePRS=includePRS) else: result = F.resultant(G) if not opt.polys: if includePRS: return result.as_expr(), [r.as_expr() for r in R] return result.as_expr() else: if includePRS: return result, R return result @public def discriminant(f, *gens, **args): """ Compute discriminant of ``f``. Examples ======== >>> from sympy import discriminant >>> from sympy.abc import x >>> discriminant(x**2 + 2*x + 3) -8 """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('discriminant', 1, exc) result = F.discriminant() if not opt.polys: return result.as_expr() else: return result @public def cofactors(f, g, *gens, **args): """ Compute GCD and cofactors of ``f`` and ``g``. Returns polynomials ``(h, cff, cfg)`` such that ``h = gcd(f, g)``, and ``cff = quo(f, h)`` and ``cfg = quo(g, h)`` are, so called, cofactors of ``f`` and ``g``. Examples ======== >>> from sympy import cofactors >>> from sympy.abc import x >>> cofactors(x**2 - 1, x**2 - 3*x + 2) (x - 1, x + 1, x - 2) """ options.allowed_flags(args, ['polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: domain, (a, b) = construct_domain(exc.exprs) try: h, cff, cfg = domain.cofactors(a, b) except NotImplementedError: raise ComputationFailed('cofactors', 2, exc) else: return domain.to_sympy(h), domain.to_sympy(cff), domain.to_sympy(cfg) h, cff, cfg = F.cofactors(G) if not opt.polys: return h.as_expr(), cff.as_expr(), cfg.as_expr() else: return h, cff, cfg @public def gcd_list(seq, *gens, **args): """ Compute GCD of a list of polynomials. Examples ======== >>> from sympy import gcd_list >>> from sympy.abc import x >>> gcd_list([x**3 - 1, x**2 - 1, x**2 - 3*x + 2]) x - 1 """ seq = sympify(seq) def try_non_polynomial_gcd(seq): if not gens and not args: domain, numbers = construct_domain(seq) if not numbers: return domain.zero elif domain.is_Numerical: result, numbers = numbers[0], numbers[1:] for number in numbers: result = domain.gcd(result, number) if domain.is_one(result): break return domain.to_sympy(result) return None result = try_non_polynomial_gcd(seq) if result is not None: return result options.allowed_flags(args, ['polys']) try: polys, opt = parallel_poly_from_expr(seq, *gens, **args) # gcd for domain Q[irrational] (purely algebraic irrational) if len(seq) > 1 and all(elt.is_algebraic and elt.is_irrational for elt in seq): a = seq[-1] lst = [ (a/elt).ratsimp() for elt in seq[:-1] ] if all(frc.is_rational for frc in lst): lc = 1 for frc in lst: lc = lcm(lc, frc.as_numer_denom()[0]) return a/lc except PolificationFailed as exc: result = try_non_polynomial_gcd(exc.exprs) if result is not None: return result else: raise ComputationFailed('gcd_list', len(seq), exc) if not polys: if not opt.polys: return S.Zero else: return Poly(0, opt=opt) result, polys = polys[0], polys[1:] for poly in polys: result = result.gcd(poly) if result.is_one: break if not opt.polys: return result.as_expr() else: return result @public def gcd(f, g=None, *gens, **args): """ Compute GCD of ``f`` and ``g``. Examples ======== >>> from sympy import gcd >>> from sympy.abc import x >>> gcd(x**2 - 1, x**2 - 3*x + 2) x - 1 """ if hasattr(f, '__iter__'): if g is not None: gens = (g,) + gens return gcd_list(f, *gens, **args) elif g is None: raise TypeError("gcd() takes 2 arguments or a sequence of arguments") options.allowed_flags(args, ['polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) # gcd for domain Q[irrational] (purely algebraic irrational) a, b = map(sympify, (f, g)) if a.is_algebraic and a.is_irrational and b.is_algebraic and b.is_irrational: frc = (a/b).ratsimp() if frc.is_rational: return a/frc.as_numer_denom()[0] except PolificationFailed as exc: domain, (a, b) = construct_domain(exc.exprs) try: return domain.to_sympy(domain.gcd(a, b)) except NotImplementedError: raise ComputationFailed('gcd', 2, exc) result = F.gcd(G) if not opt.polys: return result.as_expr() else: return result @public def lcm_list(seq, *gens, **args): """ Compute LCM of a list of polynomials. Examples ======== >>> from sympy import lcm_list >>> from sympy.abc import x >>> lcm_list([x**3 - 1, x**2 - 1, x**2 - 3*x + 2]) x**5 - x**4 - 2*x**3 - x**2 + x + 2 """ seq = sympify(seq) def try_non_polynomial_lcm(seq): if not gens and not args: domain, numbers = construct_domain(seq) if not numbers: return domain.one elif domain.is_Numerical: result, numbers = numbers[0], numbers[1:] for number in numbers: result = domain.lcm(result, number) return domain.to_sympy(result) return None result = try_non_polynomial_lcm(seq) if result is not None: return result options.allowed_flags(args, ['polys']) try: polys, opt = parallel_poly_from_expr(seq, *gens, **args) # lcm for domain Q[irrational] (purely algebraic irrational) if len(seq) > 1 and all(elt.is_algebraic and elt.is_irrational for elt in seq): a = seq[-1] lst = [ (a/elt).ratsimp() for elt in seq[:-1] ] if all(frc.is_rational for frc in lst): lc = 1 for frc in lst: lc = lcm(lc, frc.as_numer_denom()[1]) return a*lc except PolificationFailed as exc: result = try_non_polynomial_lcm(exc.exprs) if result is not None: return result else: raise ComputationFailed('lcm_list', len(seq), exc) if not polys: if not opt.polys: return S.One else: return Poly(1, opt=opt) result, polys = polys[0], polys[1:] for poly in polys: result = result.lcm(poly) if not opt.polys: return result.as_expr() else: return result @public def lcm(f, g=None, *gens, **args): """ Compute LCM of ``f`` and ``g``. Examples ======== >>> from sympy import lcm >>> from sympy.abc import x >>> lcm(x**2 - 1, x**2 - 3*x + 2) x**3 - 2*x**2 - x + 2 """ if hasattr(f, '__iter__'): if g is not None: gens = (g,) + gens return lcm_list(f, *gens, **args) elif g is None: raise TypeError("lcm() takes 2 arguments or a sequence of arguments") options.allowed_flags(args, ['polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) # lcm for domain Q[irrational] (purely algebraic irrational) a, b = map(sympify, (f, g)) if a.is_algebraic and a.is_irrational and b.is_algebraic and b.is_irrational: frc = (a/b).ratsimp() if frc.is_rational: return a*frc.as_numer_denom()[1] except PolificationFailed as exc: domain, (a, b) = construct_domain(exc.exprs) try: return domain.to_sympy(domain.lcm(a, b)) except NotImplementedError: raise ComputationFailed('lcm', 2, exc) result = F.lcm(G) if not opt.polys: return result.as_expr() else: return result @public def terms_gcd(f, *gens, **args): """ Remove GCD of terms from ``f``. If the ``deep`` flag is True, then the arguments of ``f`` will have terms_gcd applied to them. If a fraction is factored out of ``f`` and ``f`` is an Add, then an unevaluated Mul will be returned so that automatic simplification does not redistribute it. The hint ``clear``, when set to False, can be used to prevent such factoring when all coefficients are not fractions. Examples ======== >>> from sympy import terms_gcd, cos >>> from sympy.abc import x, y >>> terms_gcd(x**6*y**2 + x**3*y, x, y) x**3*y*(x**3*y + 1) The default action of polys routines is to expand the expression given to them. terms_gcd follows this behavior: >>> terms_gcd((3+3*x)*(x+x*y)) 3*x*(x*y + x + y + 1) If this is not desired then the hint ``expand`` can be set to False. In this case the expression will be treated as though it were comprised of one or more terms: >>> terms_gcd((3+3*x)*(x+x*y), expand=False) (3*x + 3)*(x*y + x) In order to traverse factors of a Mul or the arguments of other functions, the ``deep`` hint can be used: >>> terms_gcd((3 + 3*x)*(x + x*y), expand=False, deep=True) 3*x*(x + 1)*(y + 1) >>> terms_gcd(cos(x + x*y), deep=True) cos(x*(y + 1)) Rationals are factored out by default: >>> terms_gcd(x + y/2) (2*x + y)/2 Only the y-term had a coefficient that was a fraction; if one does not want to factor out the 1/2 in cases like this, the flag ``clear`` can be set to False: >>> terms_gcd(x + y/2, clear=False) x + y/2 >>> terms_gcd(x*y/2 + y**2, clear=False) y*(x/2 + y) The ``clear`` flag is ignored if all coefficients are fractions: >>> terms_gcd(x/3 + y/2, clear=False) (2*x + 3*y)/6 See Also ======== sympy.core.exprtools.gcd_terms, sympy.core.exprtools.factor_terms """ from sympy.core.relational import Equality orig = sympify(f) if not isinstance(f, Expr) or f.is_Atom: return orig if args.get('deep', False): new = f.func(*[terms_gcd(a, *gens, **args) for a in f.args]) args.pop('deep') args['expand'] = False return terms_gcd(new, *gens, **args) if isinstance(f, Equality): return f clear = args.pop('clear', True) options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: return exc.expr J, f = F.terms_gcd() if opt.domain.is_Ring: if opt.domain.is_Field: denom, f = f.clear_denoms(convert=True) coeff, f = f.primitive() if opt.domain.is_Field: coeff /= denom else: coeff = S.One term = Mul(*[x**j for x, j in zip(f.gens, J)]) if coeff == 1: coeff = S.One if term == 1: return orig if clear: return _keep_coeff(coeff, term*f.as_expr()) # base the clearing on the form of the original expression, not # the (perhaps) Mul that we have now coeff, f = _keep_coeff(coeff, f.as_expr(), clear=False).as_coeff_Mul() return _keep_coeff(coeff, term*f, clear=False) @public def trunc(f, p, *gens, **args): """ Reduce ``f`` modulo a constant ``p``. Examples ======== >>> from sympy import trunc >>> from sympy.abc import x >>> trunc(2*x**3 + 3*x**2 + 5*x + 7, 3) -x**3 - x + 1 """ options.allowed_flags(args, ['auto', 'polys']) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('trunc', 1, exc) result = F.trunc(sympify(p)) if not opt.polys: return result.as_expr() else: return result @public def monic(f, *gens, **args): """ Divide all coefficients of ``f`` by ``LC(f)``. Examples ======== >>> from sympy import monic >>> from sympy.abc import x >>> monic(3*x**2 + 4*x + 2) x**2 + 4*x/3 + 2/3 """ options.allowed_flags(args, ['auto', 'polys']) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('monic', 1, exc) result = F.monic(auto=opt.auto) if not opt.polys: return result.as_expr() else: return result @public def content(f, *gens, **args): """ Compute GCD of coefficients of ``f``. Examples ======== >>> from sympy import content >>> from sympy.abc import x >>> content(6*x**2 + 8*x + 12) 2 """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('content', 1, exc) return F.content() @public def primitive(f, *gens, **args): """ Compute content and the primitive form of ``f``. Examples ======== >>> from sympy.polys.polytools import primitive >>> from sympy.abc import x >>> primitive(6*x**2 + 8*x + 12) (2, 3*x**2 + 4*x + 6) >>> eq = (2 + 2*x)*x + 2 Expansion is performed by default: >>> primitive(eq) (2, x**2 + x + 1) Set ``expand`` to False to shut this off. Note that the extraction will not be recursive; use the as_content_primitive method for recursive, non-destructive Rational extraction. >>> primitive(eq, expand=False) (1, x*(2*x + 2) + 2) >>> eq.as_content_primitive() (2, x*(x + 1) + 1) """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('primitive', 1, exc) cont, result = F.primitive() if not opt.polys: return cont, result.as_expr() else: return cont, result @public def compose(f, g, *gens, **args): """ Compute functional composition ``f(g)``. Examples ======== >>> from sympy import compose >>> from sympy.abc import x >>> compose(x**2 + x, x - 1) x**2 - x """ options.allowed_flags(args, ['polys']) try: (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args) except PolificationFailed as exc: raise ComputationFailed('compose', 2, exc) result = F.compose(G) if not opt.polys: return result.as_expr() else: return result @public def decompose(f, *gens, **args): """ Compute functional decomposition of ``f``. Examples ======== >>> from sympy import decompose >>> from sympy.abc import x >>> decompose(x**4 + 2*x**3 - x - 1) [x**2 - x - 1, x**2 + x] """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('decompose', 1, exc) result = F.decompose() if not opt.polys: return [r.as_expr() for r in result] else: return result @public def sturm(f, *gens, **args): """ Compute Sturm sequence of ``f``. Examples ======== >>> from sympy import sturm >>> from sympy.abc import x >>> sturm(x**3 - 2*x**2 + x - 3) [x**3 - 2*x**2 + x - 3, 3*x**2 - 4*x + 1, 2*x/9 + 25/9, -2079/4] """ options.allowed_flags(args, ['auto', 'polys']) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('sturm', 1, exc) result = F.sturm(auto=opt.auto) if not opt.polys: return [r.as_expr() for r in result] else: return result @public def gff_list(f, *gens, **args): """ Compute a list of greatest factorial factors of ``f``. Note that the input to ff() and rf() should be Poly instances to use the definitions here. Examples ======== >>> from sympy import gff_list, ff, Poly >>> from sympy.abc import x >>> f = Poly(x**5 + 2*x**4 - x**3 - 2*x**2, x) >>> gff_list(f) [(Poly(x, x, domain='ZZ'), 1), (Poly(x + 2, x, domain='ZZ'), 4)] >>> (ff(Poly(x), 1)*ff(Poly(x + 2), 4)).expand() == f True >>> f = Poly(x**12 + 6*x**11 - 11*x**10 - 56*x**9 + 220*x**8 + 208*x**7 - \ 1401*x**6 + 1090*x**5 + 2715*x**4 - 6720*x**3 - 1092*x**2 + 5040*x, x) >>> gff_list(f) [(Poly(x**3 + 7, x, domain='ZZ'), 2), (Poly(x**2 + 5*x, x, domain='ZZ'), 3)] >>> ff(Poly(x**3 + 7, x), 2)*ff(Poly(x**2 + 5*x, x), 3) == f True """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('gff_list', 1, exc) factors = F.gff_list() if not opt.polys: return [(g.as_expr(), k) for g, k in factors] else: return factors @public def gff(f, *gens, **args): """Compute greatest factorial factorization of ``f``. """ raise NotImplementedError('symbolic falling factorial') @public def sqf_norm(f, *gens, **args): """ Compute square-free norm of ``f``. Returns ``s``, ``f``, ``r``, such that ``g(x) = f(x-sa)`` and ``r(x) = Norm(g(x))`` is a square-free polynomial over ``K``, where ``a`` is the algebraic extension of the ground domain. Examples ======== >>> from sympy import sqf_norm, sqrt >>> from sympy.abc import x >>> sqf_norm(x**2 + 1, extension=[sqrt(3)]) (1, x**2 - 2*sqrt(3)*x + 4, x**4 - 4*x**2 + 16) """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('sqf_norm', 1, exc) s, g, r = F.sqf_norm() if not opt.polys: return Integer(s), g.as_expr(), r.as_expr() else: return Integer(s), g, r @public def sqf_part(f, *gens, **args): """ Compute square-free part of ``f``. Examples ======== >>> from sympy import sqf_part >>> from sympy.abc import x >>> sqf_part(x**3 - 3*x - 2) x**2 - x - 2 """ options.allowed_flags(args, ['polys']) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('sqf_part', 1, exc) result = F.sqf_part() if not opt.polys: return result.as_expr() else: return result def _sorted_factors(factors, method): """Sort a list of ``(expr, exp)`` pairs. """ if method == 'sqf': def key(obj): poly, exp = obj rep = poly.rep.rep return (exp, len(rep), len(poly.gens), rep) else: def key(obj): poly, exp = obj rep = poly.rep.rep return (len(rep), len(poly.gens), exp, rep) return sorted(factors, key=key) def _factors_product(factors): """Multiply a list of ``(expr, exp)`` pairs. """ return Mul(*[f.as_expr()**k for f, k in factors]) def _symbolic_factor_list(expr, opt, method): """Helper function for :func:`_symbolic_factor`. """ coeff, factors = S.One, [] args = [i._eval_factor() if hasattr(i, '_eval_factor') else i for i in Mul.make_args(expr)] for arg in args: if arg.is_Number: coeff *= arg continue if arg.is_Mul: args.extend(arg.args) continue if arg.is_Pow: base, exp = arg.args if base.is_Number and exp.is_Number: coeff *= arg continue if base.is_Number: factors.append((base, exp)) continue else: base, exp = arg, S.One try: poly, _ = _poly_from_expr(base, opt) except PolificationFailed as exc: factors.append((exc.expr, exp)) else: func = getattr(poly, method + '_list') _coeff, _factors = func() if _coeff is not S.One: if exp.is_Integer: coeff *= _coeff**exp elif _coeff.is_positive: factors.append((_coeff, exp)) else: _factors.append((_coeff, S.One)) if exp is S.One: factors.extend(_factors) elif exp.is_integer: factors.extend([(f, k*exp) for f, k in _factors]) else: other = [] for f, k in _factors: if f.as_expr().is_positive: factors.append((f, k*exp)) else: other.append((f, k)) factors.append((_factors_product(other), exp)) return coeff, factors def _symbolic_factor(expr, opt, method): """Helper function for :func:`_factor`. """ if isinstance(expr, Expr) and not expr.is_Relational: if hasattr(expr,'_eval_factor'): return expr._eval_factor() coeff, factors = _symbolic_factor_list(together(expr), opt, method) return _keep_coeff(coeff, _factors_product(factors)) elif hasattr(expr, 'args'): return expr.func(*[_symbolic_factor(arg, opt, method) for arg in expr.args]) elif hasattr(expr, '__iter__'): return expr.__class__([_symbolic_factor(arg, opt, method) for arg in expr]) else: return expr def _generic_factor_list(expr, gens, args, method): """Helper function for :func:`sqf_list` and :func:`factor_list`. """ options.allowed_flags(args, ['frac', 'polys']) opt = options.build_options(gens, args) expr = sympify(expr) if isinstance(expr, Expr) and not expr.is_Relational: numer, denom = together(expr).as_numer_denom() cp, fp = _symbolic_factor_list(numer, opt, method) cq, fq = _symbolic_factor_list(denom, opt, method) if fq and not opt.frac: raise PolynomialError("a polynomial expected, got %s" % expr) _opt = opt.clone(dict(expand=True)) for factors in (fp, fq): for i, (f, k) in enumerate(factors): if not f.is_Poly: f, _ = _poly_from_expr(f, _opt) factors[i] = (f, k) fp = _sorted_factors(fp, method) fq = _sorted_factors(fq, method) if not opt.polys: fp = [(f.as_expr(), k) for f, k in fp] fq = [(f.as_expr(), k) for f, k in fq] coeff = cp/cq if not opt.frac: return coeff, fp else: return coeff, fp, fq else: raise PolynomialError("a polynomial expected, got %s" % expr) def _generic_factor(expr, gens, args, method): """Helper function for :func:`sqf` and :func:`factor`. """ options.allowed_flags(args, []) opt = options.build_options(gens, args) return _symbolic_factor(sympify(expr), opt, method) def to_rational_coeffs(f): """ try to transform a polynomial to have rational coefficients try to find a transformation ``x = alpha*y`` ``f(x) = lc*alpha**n * g(y)`` where ``g`` is a polynomial with rational coefficients, ``lc`` the leading coefficient. If this fails, try ``x = y + beta`` ``f(x) = g(y)`` Returns ``None`` if ``g`` not found; ``(lc, alpha, None, g)`` in case of rescaling ``(None, None, beta, g)`` in case of translation Notes ===== Currently it transforms only polynomials without roots larger than 2. Examples ======== >>> from sympy import sqrt, Poly, simplify >>> from sympy.polys.polytools import to_rational_coeffs >>> from sympy.abc import x >>> p = Poly(((x**2-1)*(x-2)).subs({x:x*(1 + sqrt(2))}), x, domain='EX') >>> lc, r, _, g = to_rational_coeffs(p) >>> lc, r (7 + 5*sqrt(2), -2*sqrt(2) + 2) >>> g Poly(x**3 + x**2 - 1/4*x - 1/4, x, domain='QQ') >>> r1 = simplify(1/r) >>> Poly(lc*r**3*(g.as_expr()).subs({x:x*r1}), x, domain='EX') == p True """ from sympy.simplify.simplify import simplify def _try_rescale(f, f1=None): """ try rescaling ``x -> alpha*x`` to convert f to a polynomial with rational coefficients. Returns ``alpha, f``; if the rescaling is successful, ``alpha`` is the rescaling factor, and ``f`` is the rescaled polynomial; else ``alpha`` is ``None``. """ from sympy.core.add import Add if not len(f.gens) == 1 or not (f.gens[0]).is_Atom: return None, f n = f.degree() lc = f.LC() f1 = f1 or f1.monic() coeffs = f1.all_coeffs()[1:] coeffs = [simplify(coeffx) for coeffx in coeffs] if coeffs[-2]: rescale1_x = simplify(coeffs[-2]/coeffs[-1]) coeffs1 = [] for i in range(len(coeffs)): coeffx = simplify(coeffs[i]*rescale1_x**(i + 1)) if not coeffx.is_rational: break coeffs1.append(coeffx) else: rescale_x = simplify(1/rescale1_x) x = f.gens[0] v = [x**n] for i in range(1, n + 1): v.append(coeffs1[i - 1]*x**(n - i)) f = Add(*v) f = Poly(f) return lc, rescale_x, f return None def _try_translate(f, f1=None): """ try translating ``x -> x + alpha`` to convert f to a polynomial with rational coefficients. Returns ``alpha, f``; if the translating is successful, ``alpha`` is the translating factor, and ``f`` is the shifted polynomial; else ``alpha`` is ``None``. """ from sympy.core.add import Add if not len(f.gens) == 1 or not (f.gens[0]).is_Atom: return None, f n = f.degree() f1 = f1 or f1.monic() coeffs = f1.all_coeffs()[1:] c = simplify(coeffs[0]) if c and not c.is_rational: func = Add if c.is_Add: args = c.args func = c.func else: args = [c] c1, c2 = sift(args, lambda z: z.is_rational, binary=True) alpha = -func(*c2)/n f2 = f1.shift(alpha) return alpha, f2 return None def _has_square_roots(p): """ Return True if ``f`` is a sum with square roots but no other root """ from sympy.core.exprtools import Factors coeffs = p.coeffs() has_sq = False for y in coeffs: for x in Add.make_args(y): f = Factors(x).factors r = [wx.q for b, wx in f.items() if b.is_number and wx.is_Rational and wx.q >= 2] if not r: continue if min(r) == 2: has_sq = True if max(r) > 2: return False return has_sq if f.get_domain().is_EX and _has_square_roots(f): f1 = f.monic() r = _try_rescale(f, f1) if r: return r[0], r[1], None, r[2] else: r = _try_translate(f, f1) if r: return None, None, r[0], r[1] return None def _torational_factor_list(p, x): """ helper function to factor polynomial using to_rational_coeffs Examples ======== >>> from sympy.polys.polytools import _torational_factor_list >>> from sympy.abc import x >>> from sympy import sqrt, expand, Mul >>> p = expand(((x**2-1)*(x-2)).subs({x:x*(1 + sqrt(2))})) >>> factors = _torational_factor_list(p, x); factors (-2, [(-x*(1 + sqrt(2))/2 + 1, 1), (-x*(1 + sqrt(2)) - 1, 1), (-x*(1 + sqrt(2)) + 1, 1)]) >>> expand(factors[0]*Mul(*[z[0] for z in factors[1]])) == p True >>> p = expand(((x**2-1)*(x-2)).subs({x:x + sqrt(2)})) >>> factors = _torational_factor_list(p, x); factors (1, [(x - 2 + sqrt(2), 1), (x - 1 + sqrt(2), 1), (x + 1 + sqrt(2), 1)]) >>> expand(factors[0]*Mul(*[z[0] for z in factors[1]])) == p True """ from sympy.simplify.simplify import simplify p1 = Poly(p, x, domain='EX') n = p1.degree() res = to_rational_coeffs(p1) if not res: return None lc, r, t, g = res factors = factor_list(g.as_expr()) if lc: c = simplify(factors[0]*lc*r**n) r1 = simplify(1/r) a = [] for z in factors[1:][0]: a.append((simplify(z[0].subs({x: x*r1})), z[1])) else: c = factors[0] a = [] for z in factors[1:][0]: a.append((z[0].subs({x: x - t}), z[1])) return (c, a) @public def sqf_list(f, *gens, **args): """ Compute a list of square-free factors of ``f``. Examples ======== >>> from sympy import sqf_list >>> from sympy.abc import x >>> sqf_list(2*x**5 + 16*x**4 + 50*x**3 + 76*x**2 + 56*x + 16) (2, [(x + 1, 2), (x + 2, 3)]) """ return _generic_factor_list(f, gens, args, method='sqf') @public def sqf(f, *gens, **args): """ Compute square-free factorization of ``f``. Examples ======== >>> from sympy import sqf >>> from sympy.abc import x >>> sqf(2*x**5 + 16*x**4 + 50*x**3 + 76*x**2 + 56*x + 16) 2*(x + 1)**2*(x + 2)**3 """ return _generic_factor(f, gens, args, method='sqf') @public def factor_list(f, *gens, **args): """ Compute a list of irreducible factors of ``f``. Examples ======== >>> from sympy import factor_list >>> from sympy.abc import x, y >>> factor_list(2*x**5 + 2*x**4*y + 4*x**3 + 4*x**2*y + 2*x + 2*y) (2, [(x + y, 1), (x**2 + 1, 2)]) """ return _generic_factor_list(f, gens, args, method='factor') @public def factor(f, *gens, **args): """ Compute the factorization of expression, ``f``, into irreducibles. (To factor an integer into primes, use ``factorint``.) There two modes implemented: symbolic and formal. If ``f`` is not an instance of :class:`Poly` and generators are not specified, then the former mode is used. Otherwise, the formal mode is used. In symbolic mode, :func:`factor` will traverse the expression tree and factor its components without any prior expansion, unless an instance of :class:`Add` is encountered (in this case formal factorization is used). This way :func:`factor` can handle large or symbolic exponents. By default, the factorization is computed over the rationals. To factor over other domain, e.g. an algebraic or finite field, use appropriate options: ``extension``, ``modulus`` or ``domain``. Examples ======== >>> from sympy import factor, sqrt >>> from sympy.abc import x, y >>> factor(2*x**5 + 2*x**4*y + 4*x**3 + 4*x**2*y + 2*x + 2*y) 2*(x + y)*(x**2 + 1)**2 >>> factor(x**2 + 1) x**2 + 1 >>> factor(x**2 + 1, modulus=2) (x + 1)**2 >>> factor(x**2 + 1, gaussian=True) (x - I)*(x + I) >>> factor(x**2 - 2, extension=sqrt(2)) (x - sqrt(2))*(x + sqrt(2)) >>> factor((x**2 - 1)/(x**2 + 4*x + 4)) (x - 1)*(x + 1)/(x + 2)**2 >>> factor((x**2 + 4*x + 4)**10000000*(x**2 + 1)) (x + 2)**20000000*(x**2 + 1) By default, factor deals with an expression as a whole: >>> eq = 2**(x**2 + 2*x + 1) >>> factor(eq) 2**(x**2 + 2*x + 1) If the ``deep`` flag is True then subexpressions will be factored: >>> factor(eq, deep=True) 2**((x + 1)**2) See Also ======== sympy.ntheory.factor_.factorint """ f = sympify(f) if args.pop('deep', False): from sympy.simplify.simplify import bottom_up def _try_factor(expr): """ Factor, but avoid changing the expression when unable to. """ fac = factor(expr) if fac.is_Mul or fac.is_Pow: return fac return expr f = bottom_up(f, _try_factor) # clean up any subexpressions that may have been expanded # while factoring out a larger expression partials = {} muladd = f.atoms(Mul, Add) for p in muladd: fac = factor(p, *gens, **args) if (fac.is_Mul or fac.is_Pow) and fac != p: partials[p] = fac return f.xreplace(partials) try: return _generic_factor(f, gens, args, method='factor') except PolynomialError as msg: if not f.is_commutative: from sympy.core.exprtools import factor_nc return factor_nc(f) else: raise PolynomialError(msg) @public def intervals(F, all=False, eps=None, inf=None, sup=None, strict=False, fast=False, sqf=False): """ Compute isolating intervals for roots of ``f``. Examples ======== >>> from sympy import intervals >>> from sympy.abc import x >>> intervals(x**2 - 3) [((-2, -1), 1), ((1, 2), 1)] >>> intervals(x**2 - 3, eps=1e-2) [((-26/15, -19/11), 1), ((19/11, 26/15), 1)] """ if not hasattr(F, '__iter__'): try: F = Poly(F) except GeneratorsNeeded: return [] return F.intervals(all=all, eps=eps, inf=inf, sup=sup, fast=fast, sqf=sqf) else: polys, opt = parallel_poly_from_expr(F, domain='QQ') if len(opt.gens) > 1: raise MultivariatePolynomialError for i, poly in enumerate(polys): polys[i] = poly.rep.rep if eps is not None: eps = opt.domain.convert(eps) if eps <= 0: raise ValueError("'eps' must be a positive rational") if inf is not None: inf = opt.domain.convert(inf) if sup is not None: sup = opt.domain.convert(sup) intervals = dup_isolate_real_roots_list(polys, opt.domain, eps=eps, inf=inf, sup=sup, strict=strict, fast=fast) result = [] for (s, t), indices in intervals: s, t = opt.domain.to_sympy(s), opt.domain.to_sympy(t) result.append(((s, t), indices)) return result @public def refine_root(f, s, t, eps=None, steps=None, fast=False, check_sqf=False): """ Refine an isolating interval of a root to the given precision. Examples ======== >>> from sympy import refine_root >>> from sympy.abc import x >>> refine_root(x**2 - 3, 1, 2, eps=1e-2) (19/11, 26/15) """ try: F = Poly(f) except GeneratorsNeeded: raise PolynomialError( "can't refine a root of %s, not a polynomial" % f) return F.refine_root(s, t, eps=eps, steps=steps, fast=fast, check_sqf=check_sqf) @public def count_roots(f, inf=None, sup=None): """ Return the number of roots of ``f`` in ``[inf, sup]`` interval. If one of ``inf`` or ``sup`` is complex, it will return the number of roots in the complex rectangle with corners at ``inf`` and ``sup``. Examples ======== >>> from sympy import count_roots, I >>> from sympy.abc import x >>> count_roots(x**4 - 4, -3, 3) 2 >>> count_roots(x**4 - 4, 0, 1 + 3*I) 1 """ try: F = Poly(f, greedy=False) except GeneratorsNeeded: raise PolynomialError("can't count roots of %s, not a polynomial" % f) return F.count_roots(inf=inf, sup=sup) @public def real_roots(f, multiple=True): """ Return a list of real roots with multiplicities of ``f``. Examples ======== >>> from sympy import real_roots >>> from sympy.abc import x >>> real_roots(2*x**3 - 7*x**2 + 4*x + 4) [-1/2, 2, 2] """ try: F = Poly(f, greedy=False) except GeneratorsNeeded: raise PolynomialError( "can't compute real roots of %s, not a polynomial" % f) return F.real_roots(multiple=multiple) @public def nroots(f, n=15, maxsteps=50, cleanup=True): """ Compute numerical approximations of roots of ``f``. Examples ======== >>> from sympy import nroots >>> from sympy.abc import x >>> nroots(x**2 - 3, n=15) [-1.73205080756888, 1.73205080756888] >>> nroots(x**2 - 3, n=30) [-1.73205080756887729352744634151, 1.73205080756887729352744634151] """ try: F = Poly(f, greedy=False) except GeneratorsNeeded: raise PolynomialError( "can't compute numerical roots of %s, not a polynomial" % f) return F.nroots(n=n, maxsteps=maxsteps, cleanup=cleanup) @public def ground_roots(f, *gens, **args): """ Compute roots of ``f`` by factorization in the ground domain. Examples ======== >>> from sympy import ground_roots >>> from sympy.abc import x >>> ground_roots(x**6 - 4*x**4 + 4*x**3 - x**2) {0: 2, 1: 2} """ options.allowed_flags(args, []) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('ground_roots', 1, exc) return F.ground_roots() @public def nth_power_roots_poly(f, n, *gens, **args): """ Construct a polynomial with n-th powers of roots of ``f``. Examples ======== >>> from sympy import nth_power_roots_poly, factor, roots >>> from sympy.abc import x >>> f = x**4 - x**2 + 1 >>> g = factor(nth_power_roots_poly(f, 2)) >>> g (x**2 - x + 1)**2 >>> R_f = [ (r**2).expand() for r in roots(f) ] >>> R_g = roots(g).keys() >>> set(R_f) == set(R_g) True """ options.allowed_flags(args, []) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('nth_power_roots_poly', 1, exc) result = F.nth_power_roots_poly(n) if not opt.polys: return result.as_expr() else: return result @public def cancel(f, *gens, **args): """ Cancel common factors in a rational function ``f``. Examples ======== >>> from sympy import cancel, sqrt, Symbol >>> from sympy.abc import x >>> A = Symbol('A', commutative=False) >>> cancel((2*x**2 - 2)/(x**2 - 2*x + 1)) (2*x + 2)/(x - 1) >>> cancel((sqrt(3) + sqrt(15)*A)/(sqrt(2) + sqrt(10)*A)) sqrt(6)/2 """ from sympy.core.exprtools import factor_terms from sympy.functions.elementary.piecewise import Piecewise options.allowed_flags(args, ['polys']) f = sympify(f) if not isinstance(f, (tuple, Tuple)): if f.is_Number or isinstance(f, Relational) or not isinstance(f, Expr): return f f = factor_terms(f, radical=True) p, q = f.as_numer_denom() elif len(f) == 2: p, q = f elif isinstance(f, Tuple): return factor_terms(f) else: raise ValueError('unexpected argument: %s' % f) try: (F, G), opt = parallel_poly_from_expr((p, q), *gens, **args) except PolificationFailed: if not isinstance(f, (tuple, Tuple)): return f else: return S.One, p, q except PolynomialError as msg: if f.is_commutative and not f.has(Piecewise): raise PolynomialError(msg) # Handling of noncommutative and/or piecewise expressions if f.is_Add or f.is_Mul: c, nc = sift(f.args, lambda x: x.is_commutative is True and not x.has(Piecewise), binary=True) nc = [cancel(i) for i in nc] return f.func(cancel(f.func._from_args(c)), *nc) else: reps = [] pot = preorder_traversal(f) next(pot) for e in pot: # XXX: This should really skip anything that's not Expr. if isinstance(e, (tuple, Tuple, BooleanAtom)): continue try: reps.append((e, cancel(e))) pot.skip() # this was handled successfully except NotImplementedError: pass return f.xreplace(dict(reps)) c, P, Q = F.cancel(G) if not isinstance(f, (tuple, Tuple)): return c*(P.as_expr()/Q.as_expr()) else: if not opt.polys: return c, P.as_expr(), Q.as_expr() else: return c, P, Q @public def reduced(f, G, *gens, **args): """ Reduces a polynomial ``f`` modulo a set of polynomials ``G``. Given a polynomial ``f`` and a set of polynomials ``G = (g_1, ..., g_n)``, computes a set of quotients ``q = (q_1, ..., q_n)`` and the remainder ``r`` such that ``f = q_1*g_1 + ... + q_n*g_n + r``, where ``r`` vanishes or ``r`` is a completely reduced polynomial with respect to ``G``. Examples ======== >>> from sympy import reduced >>> from sympy.abc import x, y >>> reduced(2*x**4 + y**2 - x**2 + y**3, [x**3 - x, y**3 - y]) ([2*x, 1], x**2 + y**2 + y) """ options.allowed_flags(args, ['polys', 'auto']) try: polys, opt = parallel_poly_from_expr([f] + list(G), *gens, **args) except PolificationFailed as exc: raise ComputationFailed('reduced', 0, exc) domain = opt.domain retract = False if opt.auto and domain.is_Ring and not domain.is_Field: opt = opt.clone(dict(domain=domain.get_field())) retract = True from sympy.polys.rings import xring _ring, _ = xring(opt.gens, opt.domain, opt.order) for i, poly in enumerate(polys): poly = poly.set_domain(opt.domain).rep.to_dict() polys[i] = _ring.from_dict(poly) Q, r = polys[0].div(polys[1:]) Q = [Poly._from_dict(dict(q), opt) for q in Q] r = Poly._from_dict(dict(r), opt) if retract: try: _Q, _r = [q.to_ring() for q in Q], r.to_ring() except CoercionFailed: pass else: Q, r = _Q, _r if not opt.polys: return [q.as_expr() for q in Q], r.as_expr() else: return Q, r @public def groebner(F, *gens, **args): """ Computes the reduced Groebner basis for a set of polynomials. Use the ``order`` argument to set the monomial ordering that will be used to compute the basis. Allowed orders are ``lex``, ``grlex`` and ``grevlex``. If no order is specified, it defaults to ``lex``. For more information on Groebner bases, see the references and the docstring of `solve_poly_system()`. Examples ======== Example taken from [1]. >>> from sympy import groebner >>> from sympy.abc import x, y >>> F = [x*y - 2*y, 2*y**2 - x**2] >>> groebner(F, x, y, order='lex') GroebnerBasis([x**2 - 2*y**2, x*y - 2*y, y**3 - 2*y], x, y, domain='ZZ', order='lex') >>> groebner(F, x, y, order='grlex') GroebnerBasis([y**3 - 2*y, x**2 - 2*y**2, x*y - 2*y], x, y, domain='ZZ', order='grlex') >>> groebner(F, x, y, order='grevlex') GroebnerBasis([y**3 - 2*y, x**2 - 2*y**2, x*y - 2*y], x, y, domain='ZZ', order='grevlex') By default, an improved implementation of the Buchberger algorithm is used. Optionally, an implementation of the F5B algorithm can be used. The algorithm can be set using ``method`` flag or with the :func:`setup` function from :mod:`sympy.polys.polyconfig`: >>> F = [x**2 - x - 1, (2*x - 1) * y - (x**10 - (1 - x)**10)] >>> groebner(F, x, y, method='buchberger') GroebnerBasis([x**2 - x - 1, y - 55], x, y, domain='ZZ', order='lex') >>> groebner(F, x, y, method='f5b') GroebnerBasis([x**2 - x - 1, y - 55], x, y, domain='ZZ', order='lex') References ========== 1. [Buchberger01]_ 2. [Cox97]_ """ return GroebnerBasis(F, *gens, **args) @public def is_zero_dimensional(F, *gens, **args): """ Checks if the ideal generated by a Groebner basis is zero-dimensional. The algorithm checks if the set of monomials not divisible by the leading monomial of any element of ``F`` is bounded. References ========== David A. Cox, John B. Little, Donal O'Shea. Ideals, Varieties and Algorithms, 3rd edition, p. 230 """ return GroebnerBasis(F, *gens, **args).is_zero_dimensional @public class GroebnerBasis(Basic): """Represents a reduced Groebner basis. """ def __new__(cls, F, *gens, **args): """Compute a reduced Groebner basis for a system of polynomials. """ options.allowed_flags(args, ['polys', 'method']) try: polys, opt = parallel_poly_from_expr(F, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('groebner', len(F), exc) from sympy.polys.rings import PolyRing ring = PolyRing(opt.gens, opt.domain, opt.order) polys = [ring.from_dict(poly.rep.to_dict()) for poly in polys if poly] G = _groebner(polys, ring, method=opt.method) G = [Poly._from_dict(g, opt) for g in G] return cls._new(G, opt) @classmethod def _new(cls, basis, options): obj = Basic.__new__(cls) obj._basis = tuple(basis) obj._options = options return obj @property def args(self): return (Tuple(*self._basis), Tuple(*self._options.gens)) @property def exprs(self): return [poly.as_expr() for poly in self._basis] @property def polys(self): return list(self._basis) @property def gens(self): return self._options.gens @property def domain(self): return self._options.domain @property def order(self): return self._options.order def __len__(self): return len(self._basis) def __iter__(self): if self._options.polys: return iter(self.polys) else: return iter(self.exprs) def __getitem__(self, item): if self._options.polys: basis = self.polys else: basis = self.exprs return basis[item] def __hash__(self): return hash((self._basis, tuple(self._options.items()))) def __eq__(self, other): if isinstance(other, self.__class__): return self._basis == other._basis and self._options == other._options elif iterable(other): return self.polys == list(other) or self.exprs == list(other) else: return False def __ne__(self, other): return not self == other @property def is_zero_dimensional(self): """ Checks if the ideal generated by a Groebner basis is zero-dimensional. The algorithm checks if the set of monomials not divisible by the leading monomial of any element of ``F`` is bounded. References ========== David A. Cox, John B. Little, Donal O'Shea. Ideals, Varieties and Algorithms, 3rd edition, p. 230 """ def single_var(monomial): return sum(map(bool, monomial)) == 1 exponents = Monomial([0]*len(self.gens)) order = self._options.order for poly in self.polys: monomial = poly.LM(order=order) if single_var(monomial): exponents *= monomial # If any element of the exponents vector is zero, then there's # a variable for which there's no degree bound and the ideal # generated by this Groebner basis isn't zero-dimensional. return all(exponents) def fglm(self, order): """ Convert a Groebner basis from one ordering to another. The FGLM algorithm converts reduced Groebner bases of zero-dimensional ideals from one ordering to another. This method is often used when it is infeasible to compute a Groebner basis with respect to a particular ordering directly. Examples ======== >>> from sympy.abc import x, y >>> from sympy import groebner >>> F = [x**2 - 3*y - x + 1, y**2 - 2*x + y - 1] >>> G = groebner(F, x, y, order='grlex') >>> list(G.fglm('lex')) [2*x - y**2 - y + 1, y**4 + 2*y**3 - 3*y**2 - 16*y + 7] >>> list(groebner(F, x, y, order='lex')) [2*x - y**2 - y + 1, y**4 + 2*y**3 - 3*y**2 - 16*y + 7] References ========== .. [1] J.C. Faugere, P. Gianni, D. Lazard, T. Mora (1994). Efficient Computation of Zero-dimensional Groebner Bases by Change of Ordering """ opt = self._options src_order = opt.order dst_order = monomial_key(order) if src_order == dst_order: return self if not self.is_zero_dimensional: raise NotImplementedError("can't convert Groebner bases of ideals with positive dimension") polys = list(self._basis) domain = opt.domain opt = opt.clone(dict( domain=domain.get_field(), order=dst_order, )) from sympy.polys.rings import xring _ring, _ = xring(opt.gens, opt.domain, src_order) for i, poly in enumerate(polys): poly = poly.set_domain(opt.domain).rep.to_dict() polys[i] = _ring.from_dict(poly) G = matrix_fglm(polys, _ring, dst_order) G = [Poly._from_dict(dict(g), opt) for g in G] if not domain.is_Field: G = [g.clear_denoms(convert=True)[1] for g in G] opt.domain = domain return self._new(G, opt) def reduce(self, expr, auto=True): """ Reduces a polynomial modulo a Groebner basis. Given a polynomial ``f`` and a set of polynomials ``G = (g_1, ..., g_n)``, computes a set of quotients ``q = (q_1, ..., q_n)`` and the remainder ``r`` such that ``f = q_1*f_1 + ... + q_n*f_n + r``, where ``r`` vanishes or ``r`` is a completely reduced polynomial with respect to ``G``. Examples ======== >>> from sympy import groebner, expand >>> from sympy.abc import x, y >>> f = 2*x**4 - x**2 + y**3 + y**2 >>> G = groebner([x**3 - x, y**3 - y]) >>> G.reduce(f) ([2*x, 1], x**2 + y**2 + y) >>> Q, r = _ >>> expand(sum(q*g for q, g in zip(Q, G)) + r) 2*x**4 - x**2 + y**3 + y**2 >>> _ == f True """ poly = Poly._from_expr(expr, self._options) polys = [poly] + list(self._basis) opt = self._options domain = opt.domain retract = False if auto and domain.is_Ring and not domain.is_Field: opt = opt.clone(dict(domain=domain.get_field())) retract = True from sympy.polys.rings import xring _ring, _ = xring(opt.gens, opt.domain, opt.order) for i, poly in enumerate(polys): poly = poly.set_domain(opt.domain).rep.to_dict() polys[i] = _ring.from_dict(poly) Q, r = polys[0].div(polys[1:]) Q = [Poly._from_dict(dict(q), opt) for q in Q] r = Poly._from_dict(dict(r), opt) if retract: try: _Q, _r = [q.to_ring() for q in Q], r.to_ring() except CoercionFailed: pass else: Q, r = _Q, _r if not opt.polys: return [q.as_expr() for q in Q], r.as_expr() else: return Q, r def contains(self, poly): """ Check if ``poly`` belongs the ideal generated by ``self``. Examples ======== >>> from sympy import groebner >>> from sympy.abc import x, y >>> f = 2*x**3 + y**3 + 3*y >>> G = groebner([x**2 + y**2 - 1, x*y - 2]) >>> G.contains(f) True >>> G.contains(f + 1) False """ return self.reduce(poly)[1] == 0 @public def poly(expr, *gens, **args): """ Efficiently transform an expression into a polynomial. Examples ======== >>> from sympy import poly >>> from sympy.abc import x >>> poly(x*(x**2 + x - 1)**2) Poly(x**5 + 2*x**4 - x**3 - 2*x**2 + x, x, domain='ZZ') """ options.allowed_flags(args, []) def _poly(expr, opt): terms, poly_terms = [], [] for term in Add.make_args(expr): factors, poly_factors = [], [] for factor in Mul.make_args(term): if factor.is_Add: poly_factors.append(_poly(factor, opt)) elif factor.is_Pow and factor.base.is_Add and \ factor.exp.is_Integer and factor.exp >= 0: poly_factors.append( _poly(factor.base, opt).pow(factor.exp)) else: factors.append(factor) if not poly_factors: terms.append(term) else: product = poly_factors[0] for factor in poly_factors[1:]: product = product.mul(factor) if factors: factor = Mul(*factors) if factor.is_Number: product = product.mul(factor) else: product = product.mul(Poly._from_expr(factor, opt)) poly_terms.append(product) if not poly_terms: result = Poly._from_expr(expr, opt) else: result = poly_terms[0] for term in poly_terms[1:]: result = result.add(term) if terms: term = Add(*terms) if term.is_Number: result = result.add(term) else: result = result.add(Poly._from_expr(term, opt)) return result.reorder(*opt.get('gens', ()), **args) expr = sympify(expr) if expr.is_Poly: return Poly(expr, *gens, **args) if 'expand' not in args: args['expand'] = False opt = options.build_options(gens, args) return _poly(expr, opt)

1aebd2f54f4bf615d68f0a352f0644f7ff57531c27895085a463b16ed1e3fc9f

"""Functions for generating interesting polynomials, e.g. for benchmarking. """ from __future__ import print_function, division from sympy.core import Add, Mul, Symbol, sympify, Dummy, symbols from sympy.core.compatibility import range from sympy.core.singleton import S from sympy.functions.elementary.miscellaneous import sqrt from sympy.ntheory import nextprime from sympy.polys.densearith import ( dmp_add_term, dmp_neg, dmp_mul, dmp_sqr ) from sympy.polys.densebasic import ( dmp_zero, dmp_one, dmp_ground, dup_from_raw_dict, dmp_raise, dup_random ) from sympy.polys.domains import ZZ from sympy.polys.factortools import dup_zz_cyclotomic_poly from sympy.polys.polyclasses import DMP from sympy.polys.polytools import Poly, PurePoly from sympy.polys.polyutils import _analyze_gens from sympy.utilities import subsets, public @public def swinnerton_dyer_poly(n, x=None, polys=False): """Generates n-th Swinnerton-Dyer polynomial in `x`. Parameters ---------- n : int `n` decides the order of polynomial x : optional polys : bool, optional ``polys=True`` returns an expression, otherwise (default) returns an expression. """ from .numberfields import minimal_polynomial if n <= 0: raise ValueError( "can't generate Swinnerton-Dyer polynomial of order %s" % n) if x is not None: sympify(x) else: x = Dummy('x') if n > 3: p = 2 a = [sqrt(2)] for i in range(2, n + 1): p = nextprime(p) a.append(sqrt(p)) return minimal_polynomial(Add(*a), x, polys=polys) if n == 1: ex = x**2 - 2 elif n == 2: ex = x**4 - 10*x**2 + 1 elif n == 3: ex = x**8 - 40*x**6 + 352*x**4 - 960*x**2 + 576 return PurePoly(ex, x) if polys else ex @public def cyclotomic_poly(n, x=None, polys=False): """Generates cyclotomic polynomial of order `n` in `x`. Parameters ---------- n : int `n` decides the order of polynomial x : optional polys : bool, optional ``polys=True`` returns an expression, otherwise (default) returns an expression. """ if n <= 0: raise ValueError( "can't generate cyclotomic polynomial of order %s" % n) poly = DMP(dup_zz_cyclotomic_poly(int(n), ZZ), ZZ) if x is not None: poly = Poly.new(poly, x) else: poly = PurePoly.new(poly, Dummy('x')) return poly if polys else poly.as_expr() @public def symmetric_poly(n, *gens, **args): """Generates symmetric polynomial of order `n`. Returns a Poly object when ``polys=True``, otherwise (default) returns an expression. """ # TODO: use an explicit keyword argument when Python 2 support is dropped gens = _analyze_gens(gens) if n < 0 or n > len(gens) or not gens: raise ValueError("can't generate symmetric polynomial of order %s for %s" % (n, gens)) elif not n: poly = S.One else: poly = Add(*[Mul(*s) for s in subsets(gens, int(n))]) if not args.get('polys', False): return poly else: return Poly(poly, *gens) @public def random_poly(x, n, inf, sup, domain=ZZ, polys=False): """Generates a polynomial of degree ``n`` with coefficients in ``[inf, sup]``. Parameters ---------- x `x` is the independent term of polynomial n : int `n` decides the order of polynomial inf Lower limit of range in which coefficients lie sup Upper limit of range in which coefficients lie domain : optional Decides what ring the coefficients are supposed to belong. Default is set to Integers. polys : bool, optional ``polys=True`` returns an expression, otherwise (default) returns an expression. """ poly = Poly(dup_random(n, inf, sup, domain), x, domain=domain) return poly if polys else poly.as_expr() @public def interpolating_poly(n, x, X='x', Y='y'): """Construct Lagrange interpolating polynomial for ``n`` data points. """ if isinstance(X, str): X = symbols("%s:%s" % (X, n)) if isinstance(Y, str): Y = symbols("%s:%s" % (Y, n)) coeffs = [] numert = Mul(*[(x - u) for u in X]) for i in range(n): numer = numert/(x - X[i]) denom = Mul(*[(X[i] - X[j]) for j in range(n) if i != j]) coeffs.append(numer/denom) return Add(*[coeff*y for coeff, y in zip(coeffs, Y)]) def fateman_poly_F_1(n): """Fateman's GCD benchmark: trivial GCD """ Y = [Symbol('y_' + str(i)) for i in range(n + 1)] y_0, y_1 = Y[0], Y[1] u = y_0 + Add(*[y for y in Y[1:]]) v = y_0**2 + Add(*[y**2 for y in Y[1:]]) F = ((u + 1)*(u + 2)).as_poly(*Y) G = ((v + 1)*(-3*y_1*y_0**2 + y_1**2 - 1)).as_poly(*Y) H = Poly(1, *Y) return F, G, H def dmp_fateman_poly_F_1(n, K): """Fateman's GCD benchmark: trivial GCD """ u = [K(1), K(0)] for i in range(n): u = [dmp_one(i, K), u] v = [K(1), K(0), K(0)] for i in range(0, n): v = [dmp_one(i, K), dmp_zero(i), v] m = n - 1 U = dmp_add_term(u, dmp_ground(K(1), m), 0, n, K) V = dmp_add_term(u, dmp_ground(K(2), m), 0, n, K) f = [[-K(3), K(0)], [], [K(1), K(0), -K(1)]] W = dmp_add_term(v, dmp_ground(K(1), m), 0, n, K) Y = dmp_raise(f, m, 1, K) F = dmp_mul(U, V, n, K) G = dmp_mul(W, Y, n, K) H = dmp_one(n, K) return F, G, H def fateman_poly_F_2(n): """Fateman's GCD benchmark: linearly dense quartic inputs """ Y = [Symbol('y_' + str(i)) for i in range(n + 1)] y_0 = Y[0] u = Add(*[y for y in Y[1:]]) H = Poly((y_0 + u + 1)**2, *Y) F = Poly((y_0 - u - 2)**2, *Y) G = Poly((y_0 + u + 2)**2, *Y) return H*F, H*G, H def dmp_fateman_poly_F_2(n, K): """Fateman's GCD benchmark: linearly dense quartic inputs """ u = [K(1), K(0)] for i in range(n - 1): u = [dmp_one(i, K), u] m = n - 1 v = dmp_add_term(u, dmp_ground(K(2), m - 1), 0, n, K) f = dmp_sqr([dmp_one(m, K), dmp_neg(v, m, K)], n, K) g = dmp_sqr([dmp_one(m, K), v], n, K) v = dmp_add_term(u, dmp_one(m - 1, K), 0, n, K) h = dmp_sqr([dmp_one(m, K), v], n, K) return dmp_mul(f, h, n, K), dmp_mul(g, h, n, K), h def fateman_poly_F_3(n): """Fateman's GCD benchmark: sparse inputs (deg f ~ vars f) """ Y = [Symbol('y_' + str(i)) for i in range(n + 1)] y_0 = Y[0] u = Add(*[y**(n + 1) for y in Y[1:]]) H = Poly((y_0**(n + 1) + u + 1)**2, *Y) F = Poly((y_0**(n + 1) - u - 2)**2, *Y) G = Poly((y_0**(n + 1) + u + 2)**2, *Y) return H*F, H*G, H def dmp_fateman_poly_F_3(n, K): """Fateman's GCD benchmark: sparse inputs (deg f ~ vars f) """ u = dup_from_raw_dict({n + 1: K.one}, K) for i in range(0, n - 1): u = dmp_add_term([u], dmp_one(i, K), n + 1, i + 1, K) v = dmp_add_term(u, dmp_ground(K(2), n - 2), 0, n, K) f = dmp_sqr( dmp_add_term([dmp_neg(v, n - 1, K)], dmp_one(n - 1, K), n + 1, n, K), n, K) g = dmp_sqr(dmp_add_term([v], dmp_one(n - 1, K), n + 1, n, K), n, K) v = dmp_add_term(u, dmp_one(n - 2, K), 0, n - 1, K) h = dmp_sqr(dmp_add_term([v], dmp_one(n - 1, K), n + 1, n, K), n, K) return dmp_mul(f, h, n, K), dmp_mul(g, h, n, K), h # A few useful polynomials from Wang's paper ('78). from sympy.polys.rings import ring def _f_0(): R, x, y, z = ring("x,y,z", ZZ) return x**2*y*z**2 + 2*x**2*y*z + 3*x**2*y + 2*x**2 + 3*x + 4*y**2*z**2 + 5*y**2*z + 6*y**2 + y*z**2 + 2*y*z + y + 1 def _f_1(): R, x, y, z = ring("x,y,z", ZZ) return x**3*y*z + x**2*y**2*z**2 + x**2*y**2 + 20*x**2*y*z + 30*x**2*y + x**2*z**2 + 10*x**2*z + x*y**3*z + 30*x*y**2*z + 20*x*y**2 + x*y*z**3 + 10*x*y*z**2 + x*y*z + 610*x*y + 20*x*z**2 + 230*x*z + 300*x + y**2*z**2 + 10*y**2*z + 30*y*z**2 + 320*y*z + 200*y + 600*z + 6000 def _f_2(): R, x, y, z = ring("x,y,z", ZZ) return x**5*y**3 + x**5*y**2*z + x**5*y*z**2 + x**5*z**3 + x**3*y**2 + x**3*y*z + 90*x**3*y + 90*x**3*z + x**2*y**2*z - 11*x**2*y**2 + x**2*z**3 - 11*x**2*z**2 + y*z - 11*y + 90*z - 990 def _f_3(): R, x, y, z = ring("x,y,z", ZZ) return x**5*y**2 + x**4*z**4 + x**4 + x**3*y**3*z + x**3*z + x**2*y**4 + x**2*y**3*z**3 + x**2*y*z**5 + x**2*y*z + x*y**2*z**4 + x*y**2 + x*y*z**7 + x*y*z**3 + x*y*z**2 + y**2*z + y*z**4 def _f_4(): R, x, y, z = ring("x,y,z", ZZ) return -x**9*y**8*z - x**8*y**5*z**3 - x**7*y**12*z**2 - 5*x**7*y**8 - x**6*y**9*z**4 + x**6*y**7*z**3 + 3*x**6*y**7*z - 5*x**6*y**5*z**2 - x**6*y**4*z**3 + x**5*y**4*z**5 + 3*x**5*y**4*z**3 - x**5*y*z**5 + x**4*y**11*z**4 + 3*x**4*y**11*z**2 - x**4*y**8*z**4 + 5*x**4*y**7*z**2 + 15*x**4*y**7 - 5*x**4*y**4*z**2 + x**3*y**8*z**6 + 3*x**3*y**8*z**4 - x**3*y**5*z**6 + 5*x**3*y**4*z**4 + 15*x**3*y**4*z**2 + x**3*y**3*z**5 + 3*x**3*y**3*z**3 - 5*x**3*y*z**4 + x**2*z**7 + 3*x**2*z**5 + x*y**7*z**6 + 3*x*y**7*z**4 + 5*x*y**3*z**4 + 15*x*y**3*z**2 + y**4*z**8 + 3*y**4*z**6 + 5*z**6 + 15*z**4 def _f_5(): R, x, y, z = ring("x,y,z", ZZ) return -x**3 - 3*x**2*y + 3*x**2*z - 3*x*y**2 + 6*x*y*z - 3*x*z**2 - y**3 + 3*y**2*z - 3*y*z**2 + z**3 def _f_6(): R, x, y, z, t = ring("x,y,z,t", ZZ) return 2115*x**4*y + 45*x**3*z**3*t**2 - 45*x**3*t**2 - 423*x*y**4 - 47*x*y**3 + 141*x*y*z**3 + 94*x*y*z*t - 9*y**3*z**3*t**2 + 9*y**3*t**2 - y**2*z**3*t**2 + y**2*t**2 + 3*z**6*t**2 + 2*z**4*t**3 - 3*z**3*t**2 - 2*z*t**3 def _w_1(): R, x, y, z = ring("x,y,z", ZZ) return 4*x**6*y**4*z**2 + 4*x**6*y**3*z**3 - 4*x**6*y**2*z**4 - 4*x**6*y*z**5 + x**5*y**4*z**3 + 12*x**5*y**3*z - x**5*y**2*z**5 + 12*x**5*y**2*z**2 - 12*x**5*y*z**3 - 12*x**5*z**4 + 8*x**4*y**4 + 6*x**4*y**3*z**2 + 8*x**4*y**3*z - 4*x**4*y**2*z**4 + 4*x**4*y**2*z**3 - 8*x**4*y**2*z**2 - 4*x**4*y*z**5 - 2*x**4*y*z**4 - 8*x**4*y*z**3 + 2*x**3*y**4*z + x**3*y**3*z**3 - x**3*y**2*z**5 - 2*x**3*y**2*z**3 + 9*x**3*y**2*z - 12*x**3*y*z**3 + 12*x**3*y*z**2 - 12*x**3*z**4 + 3*x**3*z**3 + 6*x**2*y**3 - 6*x**2*y**2*z**2 + 8*x**2*y**2*z - 2*x**2*y*z**4 - 8*x**2*y*z**3 + 2*x**2*y*z**2 + 2*x*y**3*z - 2*x*y**2*z**3 - 3*x*y*z + 3*x*z**3 - 2*y**2 + 2*y*z**2 def _w_2(): R, x, y = ring("x,y", ZZ) return 24*x**8*y**3 + 48*x**8*y**2 + 24*x**7*y**5 - 72*x**7*y**2 + 25*x**6*y**4 + 2*x**6*y**3 + 4*x**6*y + 8*x**6 + x**5*y**6 + x**5*y**3 - 12*x**5 + x**4*y**5 - x**4*y**4 - 2*x**4*y**3 + 292*x**4*y**2 - x**3*y**6 + 3*x**3*y**3 - x**2*y**5 + 12*x**2*y**3 + 48*x**2 - 12*y**3 def f_polys(): return _f_0(), _f_1(), _f_2(), _f_3(), _f_4(), _f_5(), _f_6() def w_polys(): return _w_1(), _w_2()

f4d35385830506fbb072ace1902af34dd8b08b838cd43751a56c204e0f1f9e11

"""Implementation of matrix FGLM Groebner basis conversion algorithm. """ from __future__ import print_function, division from sympy.polys.monomials import monomial_mul, monomial_div from sympy.core.compatibility import range def matrix_fglm(F, ring, O_to): """ Converts the reduced Groebner basis ``F`` of a zero-dimensional ideal w.r.t. ``O_from`` to a reduced Groebner basis w.r.t. ``O_to``. References ========== .. [1] J.C. Faugere, P. Gianni, D. Lazard, T. Mora (1994). Efficient Computation of Zero-dimensional Groebner Bases by Change of Ordering """ domain = ring.domain ngens = ring.ngens ring_to = ring.clone(order=O_to) old_basis = _basis(F, ring) M = _representing_matrices(old_basis, F, ring) # V contains the normalforms (wrt O_from) of S S = [ring.zero_monom] V = [[domain.one] + [domain.zero] * (len(old_basis) - 1)] G = [] L = [(i, 0) for i in range(ngens)] # (i, j) corresponds to x_i * S[j] L.sort(key=lambda k_l: O_to(_incr_k(S[k_l[1]], k_l[0])), reverse=True) t = L.pop() P = _identity_matrix(len(old_basis), domain) while True: s = len(S) v = _matrix_mul(M[t[0]], V[t[1]]) _lambda = _matrix_mul(P, v) if all(_lambda[i] == domain.zero for i in range(s, len(old_basis))): # there is a linear combination of v by V lt = ring.term_new(_incr_k(S[t[1]], t[0]), domain.one) rest = ring.from_dict({S[i]: _lambda[i] for i in range(s)}) g = (lt - rest).set_ring(ring_to) if g: G.append(g) else: # v is linearly independent from V P = _update(s, _lambda, P) S.append(_incr_k(S[t[1]], t[0])) V.append(v) L.extend([(i, s) for i in range(ngens)]) L = list(set(L)) L.sort(key=lambda k_l: O_to(_incr_k(S[k_l[1]], k_l[0])), reverse=True) L = [(k, l) for (k, l) in L if all(monomial_div(_incr_k(S[l], k), g.LM) is None for g in G)] if not L: G = [ g.monic() for g in G ] return sorted(G, key=lambda g: O_to(g.LM), reverse=True) t = L.pop() def _incr_k(m, k): return tuple(list(m[:k]) + [m[k] + 1] + list(m[k + 1:])) def _identity_matrix(n, domain): M = [[domain.zero]*n for _ in range(n)] for i in range(n): M[i][i] = domain.one return M def _matrix_mul(M, v): return [sum([row[i] * v[i] for i in range(len(v))]) for row in M] def _update(s, _lambda, P): """ Update ``P`` such that for the updated `P'` `P' v = e_{s}`. """ k = min([j for j in range(s, len(_lambda)) if _lambda[j] != 0]) for r in range(len(_lambda)): if r != k: P[r] = [P[r][j] - (P[k][j] * _lambda[r]) / _lambda[k] for j in range(len(P[r]))] P[k] = [P[k][j] / _lambda[k] for j in range(len(P[k]))] P[k], P[s] = P[s], P[k] return P def _representing_matrices(basis, G, ring): r""" Compute the matrices corresponding to the linear maps `m \mapsto x_i m` for all variables `x_i`. """ domain = ring.domain u = ring.ngens-1 def var(i): return tuple([0] * i + [1] + [0] * (u - i)) def representing_matrix(m): M = [[domain.zero] * len(basis) for _ in range(len(basis))] for i, v in enumerate(basis): r = ring.term_new(monomial_mul(m, v), domain.one).rem(G) for monom, coeff in r.terms(): j = basis.index(monom) M[j][i] = coeff return M return [representing_matrix(var(i)) for i in range(u + 1)] def _basis(G, ring): r""" Computes a list of monomials which are not divisible by the leading monomials wrt to ``O`` of ``G``. These monomials are a basis of `K[X_1, \ldots, X_n]/(G)`. """ order = ring.order leading_monomials = [g.LM for g in G] candidates = [ring.zero_monom] basis = [] while candidates: t = candidates.pop() basis.append(t) new_candidates = [_incr_k(t, k) for k in range(ring.ngens) if all(monomial_div(_incr_k(t, k), lmg) is None for lmg in leading_monomials)] candidates.extend(new_candidates) candidates.sort(key=lambda m: order(m), reverse=True) basis = list(set(basis)) return sorted(basis, key=lambda m: order(m))

28334eb2fe01946114eda1ade6a4ada8c1c3e6ce79337e347cc01d202c0a682f

"""Basic tools for dense recursive polynomials in ``K[x]`` or ``K[X]``. """ from __future__ import print_function, division from sympy import oo from sympy.core import igcd from sympy.core.compatibility import range from sympy.polys.monomials import monomial_min, monomial_div from sympy.polys.orderings import monomial_key import random def poly_LC(f, K): """ Return leading coefficient of ``f``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import poly_LC >>> poly_LC([], ZZ) 0 >>> poly_LC([ZZ(1), ZZ(2), ZZ(3)], ZZ) 1 """ if not f: return K.zero else: return f[0] def poly_TC(f, K): """ Return trailing coefficient of ``f``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import poly_TC >>> poly_TC([], ZZ) 0 >>> poly_TC([ZZ(1), ZZ(2), ZZ(3)], ZZ) 3 """ if not f: return K.zero else: return f[-1] dup_LC = dmp_LC = poly_LC dup_TC = dmp_TC = poly_TC def dmp_ground_LC(f, u, K): """ Return the ground leading coefficient. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_ground_LC >>> f = ZZ.map([[[1], [2, 3]]]) >>> dmp_ground_LC(f, 2, ZZ) 1 """ while u: f = dmp_LC(f, K) u -= 1 return dup_LC(f, K) def dmp_ground_TC(f, u, K): """ Return the ground trailing coefficient. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_ground_TC >>> f = ZZ.map([[[1], [2, 3]]]) >>> dmp_ground_TC(f, 2, ZZ) 3 """ while u: f = dmp_TC(f, K) u -= 1 return dup_TC(f, K) def dmp_true_LT(f, u, K): """ Return the leading term ``c * x_1**n_1 ... x_k**n_k``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_true_LT >>> f = ZZ.map([[4], [2, 0], [3, 0, 0]]) >>> dmp_true_LT(f, 1, ZZ) ((2, 0), 4) """ monom = [] while u: monom.append(len(f) - 1) f, u = f[0], u - 1 if not f: monom.append(0) else: monom.append(len(f) - 1) return tuple(monom), dup_LC(f, K) def dup_degree(f): """ Return the leading degree of ``f`` in ``K[x]``. Note that the degree of 0 is negative infinity (the SymPy object -oo). Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_degree >>> f = ZZ.map([1, 2, 0, 3]) >>> dup_degree(f) 3 """ if not f: return -oo return len(f) - 1 def dmp_degree(f, u): """ Return the leading degree of ``f`` in ``x_0`` in ``K[X]``. Note that the degree of 0 is negative infinity (the SymPy object -oo). Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_degree >>> dmp_degree([[[]]], 2) -oo >>> f = ZZ.map([[2], [1, 2, 3]]) >>> dmp_degree(f, 1) 1 """ if dmp_zero_p(f, u): return -oo else: return len(f) - 1 def _rec_degree_in(g, v, i, j): """Recursive helper function for :func:`dmp_degree_in`.""" if i == j: return dmp_degree(g, v) v, i = v - 1, i + 1 return max([ _rec_degree_in(c, v, i, j) for c in g ]) def dmp_degree_in(f, j, u): """ Return the leading degree of ``f`` in ``x_j`` in ``K[X]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_degree_in >>> f = ZZ.map([[2], [1, 2, 3]]) >>> dmp_degree_in(f, 0, 1) 1 >>> dmp_degree_in(f, 1, 1) 2 """ if not j: return dmp_degree(f, u) if j < 0 or j > u: raise IndexError("0 <= j <= %s expected, got %s" % (u, j)) return _rec_degree_in(f, u, 0, j) def _rec_degree_list(g, v, i, degs): """Recursive helper for :func:`dmp_degree_list`.""" degs[i] = max(degs[i], dmp_degree(g, v)) if v > 0: v, i = v - 1, i + 1 for c in g: _rec_degree_list(c, v, i, degs) def dmp_degree_list(f, u): """ Return a list of degrees of ``f`` in ``K[X]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_degree_list >>> f = ZZ.map([[1], [1, 2, 3]]) >>> dmp_degree_list(f, 1) (1, 2) """ degs = [-oo]*(u + 1) _rec_degree_list(f, u, 0, degs) return tuple(degs) def dup_strip(f): """ Remove leading zeros from ``f`` in ``K[x]``. Examples ======== >>> from sympy.polys.densebasic import dup_strip >>> dup_strip([0, 0, 1, 2, 3, 0]) [1, 2, 3, 0] """ if not f or f[0]: return f i = 0 for cf in f: if cf: break else: i += 1 return f[i:] def dmp_strip(f, u): """ Remove leading zeros from ``f`` in ``K[X]``. Examples ======== >>> from sympy.polys.densebasic import dmp_strip >>> dmp_strip([[], [0, 1, 2], [1]], 1) [[0, 1, 2], [1]] """ if not u: return dup_strip(f) if dmp_zero_p(f, u): return f i, v = 0, u - 1 for c in f: if not dmp_zero_p(c, v): break else: i += 1 if i == len(f): return dmp_zero(u) else: return f[i:] def _rec_validate(f, g, i, K): """Recursive helper for :func:`dmp_validate`.""" if type(g) is not list: if K is not None and not K.of_type(g): raise TypeError("%s in %s in not of type %s" % (g, f, K.dtype)) return set([i - 1]) elif not g: return set([i]) else: levels = set([]) for c in g: levels |= _rec_validate(f, c, i + 1, K) return levels def _rec_strip(g, v): """Recursive helper for :func:`_rec_strip`.""" if not v: return dup_strip(g) w = v - 1 return dmp_strip([ _rec_strip(c, w) for c in g ], v) def dmp_validate(f, K=None): """ Return the number of levels in ``f`` and recursively strip it. Examples ======== >>> from sympy.polys.densebasic import dmp_validate >>> dmp_validate([[], [0, 1, 2], [1]]) ([[1, 2], [1]], 1) >>> dmp_validate([[1], 1]) Traceback (most recent call last): ... ValueError: invalid data structure for a multivariate polynomial """ levels = _rec_validate(f, f, 0, K) u = levels.pop() if not levels: return _rec_strip(f, u), u else: raise ValueError( "invalid data structure for a multivariate polynomial") def dup_reverse(f): """ Compute ``x**n * f(1/x)``, i.e.: reverse ``f`` in ``K[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_reverse >>> f = ZZ.map([1, 2, 3, 0]) >>> dup_reverse(f) [3, 2, 1] """ return dup_strip(list(reversed(f))) def dup_copy(f): """ Create a new copy of a polynomial ``f`` in ``K[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_copy >>> f = ZZ.map([1, 2, 3, 0]) >>> dup_copy([1, 2, 3, 0]) [1, 2, 3, 0] """ return list(f) def dmp_copy(f, u): """ Create a new copy of a polynomial ``f`` in ``K[X]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_copy >>> f = ZZ.map([[1], [1, 2]]) >>> dmp_copy(f, 1) [[1], [1, 2]] """ if not u: return list(f) v = u - 1 return [ dmp_copy(c, v) for c in f ] def dup_to_tuple(f): """ Convert `f` into a tuple. This is needed for hashing. This is similar to dup_copy(). Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_copy >>> f = ZZ.map([1, 2, 3, 0]) >>> dup_copy([1, 2, 3, 0]) [1, 2, 3, 0] """ return tuple(f) def dmp_to_tuple(f, u): """ Convert `f` into a nested tuple of tuples. This is needed for hashing. This is similar to dmp_copy(). Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_to_tuple >>> f = ZZ.map([[1], [1, 2]]) >>> dmp_to_tuple(f, 1) ((1,), (1, 2)) """ if not u: return tuple(f) v = u - 1 return tuple(dmp_to_tuple(c, v) for c in f) def dup_normal(f, K): """ Normalize univariate polynomial in the given domain. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_normal >>> dup_normal([0, 1.5, 2, 3], ZZ) [1, 2, 3] """ return dup_strip([ K.normal(c) for c in f ]) def dmp_normal(f, u, K): """ Normalize a multivariate polynomial in the given domain. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_normal >>> dmp_normal([[], [0, 1.5, 2]], 1, ZZ) [[1, 2]] """ if not u: return dup_normal(f, K) v = u - 1 return dmp_strip([ dmp_normal(c, v, K) for c in f ], u) def dup_convert(f, K0, K1): """ Convert the ground domain of ``f`` from ``K0`` to ``K1``. Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_convert >>> R, x = ring("x", ZZ) >>> dup_convert([R(1), R(2)], R.to_domain(), ZZ) [1, 2] >>> dup_convert([ZZ(1), ZZ(2)], ZZ, R.to_domain()) [1, 2] """ if K0 is not None and K0 == K1: return f else: return dup_strip([ K1.convert(c, K0) for c in f ]) def dmp_convert(f, u, K0, K1): """ Convert the ground domain of ``f`` from ``K0`` to ``K1``. Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_convert >>> R, x = ring("x", ZZ) >>> dmp_convert([[R(1)], [R(2)]], 1, R.to_domain(), ZZ) [[1], [2]] >>> dmp_convert([[ZZ(1)], [ZZ(2)]], 1, ZZ, R.to_domain()) [[1], [2]] """ if not u: return dup_convert(f, K0, K1) if K0 is not None and K0 == K1: return f v = u - 1 return dmp_strip([ dmp_convert(c, v, K0, K1) for c in f ], u) def dup_from_sympy(f, K): """ Convert the ground domain of ``f`` from SymPy to ``K``. Examples ======== >>> from sympy import S >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_from_sympy >>> dup_from_sympy([S(1), S(2)], ZZ) == [ZZ(1), ZZ(2)] True """ return dup_strip([ K.from_sympy(c) for c in f ]) def dmp_from_sympy(f, u, K): """ Convert the ground domain of ``f`` from SymPy to ``K``. Examples ======== >>> from sympy import S >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_from_sympy >>> dmp_from_sympy([[S(1)], [S(2)]], 1, ZZ) == [[ZZ(1)], [ZZ(2)]] True """ if not u: return dup_from_sympy(f, K) v = u - 1 return dmp_strip([ dmp_from_sympy(c, v, K) for c in f ], u) def dup_nth(f, n, K): """ Return the ``n``-th coefficient of ``f`` in ``K[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_nth >>> f = ZZ.map([1, 2, 3]) >>> dup_nth(f, 0, ZZ) 3 >>> dup_nth(f, 4, ZZ) 0 """ if n < 0: raise IndexError("'n' must be non-negative, got %i" % n) elif n >= len(f): return K.zero else: return f[dup_degree(f) - n] def dmp_nth(f, n, u, K): """ Return the ``n``-th coefficient of ``f`` in ``K[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_nth >>> f = ZZ.map([[1], [2], [3]]) >>> dmp_nth(f, 0, 1, ZZ) [3] >>> dmp_nth(f, 4, 1, ZZ) [] """ if n < 0: raise IndexError("'n' must be non-negative, got %i" % n) elif n >= len(f): return dmp_zero(u - 1) else: return f[dmp_degree(f, u) - n] def dmp_ground_nth(f, N, u, K): """ Return the ground ``n``-th coefficient of ``f`` in ``K[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_ground_nth >>> f = ZZ.map([[1], [2, 3]]) >>> dmp_ground_nth(f, (0, 1), 1, ZZ) 2 """ v = u for n in N: if n < 0: raise IndexError("`n` must be non-negative, got %i" % n) elif n >= len(f): return K.zero else: d = dmp_degree(f, v) if d == -oo: d = -1 f, v = f[d - n], v - 1 return f def dmp_zero_p(f, u): """ Return ``True`` if ``f`` is zero in ``K[X]``. Examples ======== >>> from sympy.polys.densebasic import dmp_zero_p >>> dmp_zero_p([[[[[]]]]], 4) True >>> dmp_zero_p([[[[[1]]]]], 4) False """ while u: if len(f) != 1: return False f = f[0] u -= 1 return not f def dmp_zero(u): """ Return a multivariate zero. Examples ======== >>> from sympy.polys.densebasic import dmp_zero >>> dmp_zero(4) [[[[[]]]]] """ r = [] for i in range(u): r = [r] return r def dmp_one_p(f, u, K): """ Return ``True`` if ``f`` is one in ``K[X]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_one_p >>> dmp_one_p([[[ZZ(1)]]], 2, ZZ) True """ return dmp_ground_p(f, K.one, u) def dmp_one(u, K): """ Return a multivariate one over ``K``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_one >>> dmp_one(2, ZZ) [[[1]]] """ return dmp_ground(K.one, u) def dmp_ground_p(f, c, u): """ Return True if ``f`` is constant in ``K[X]``. Examples ======== >>> from sympy.polys.densebasic import dmp_ground_p >>> dmp_ground_p([[[3]]], 3, 2) True >>> dmp_ground_p([[[4]]], None, 2) True """ if c is not None and not c: return dmp_zero_p(f, u) while u: if len(f) != 1: return False f = f[0] u -= 1 if c is None: return len(f) <= 1 else: return f == [c] def dmp_ground(c, u): """ Return a multivariate constant. Examples ======== >>> from sympy.polys.densebasic import dmp_ground >>> dmp_ground(3, 5) [[[[[[3]]]]]] >>> dmp_ground(1, -1) 1 """ if not c: return dmp_zero(u) for i in range(u + 1): c = [c] return c def dmp_zeros(n, u, K): """ Return a list of multivariate zeros. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_zeros >>> dmp_zeros(3, 2, ZZ) [[[[]]], [[[]]], [[[]]]] >>> dmp_zeros(3, -1, ZZ) [0, 0, 0] """ if not n: return [] if u < 0: return [K.zero]*n else: return [ dmp_zero(u) for i in range(n) ] def dmp_grounds(c, n, u): """ Return a list of multivariate constants. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_grounds >>> dmp_grounds(ZZ(4), 3, 2) [[[[4]]], [[[4]]], [[[4]]]] >>> dmp_grounds(ZZ(4), 3, -1) [4, 4, 4] """ if not n: return [] if u < 0: return [c]*n else: return [ dmp_ground(c, u) for i in range(n) ] def dmp_negative_p(f, u, K): """ Return ``True`` if ``LC(f)`` is negative. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_negative_p >>> dmp_negative_p([[ZZ(1)], [-ZZ(1)]], 1, ZZ) False >>> dmp_negative_p([[-ZZ(1)], [ZZ(1)]], 1, ZZ) True """ return K.is_negative(dmp_ground_LC(f, u, K)) def dmp_positive_p(f, u, K): """ Return ``True`` if ``LC(f)`` is positive. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_positive_p >>> dmp_positive_p([[ZZ(1)], [-ZZ(1)]], 1, ZZ) True >>> dmp_positive_p([[-ZZ(1)], [ZZ(1)]], 1, ZZ) False """ return K.is_positive(dmp_ground_LC(f, u, K)) def dup_from_dict(f, K): """ Create a ``K[x]`` polynomial from a ``dict``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_from_dict >>> dup_from_dict({(0,): ZZ(7), (2,): ZZ(5), (4,): ZZ(1)}, ZZ) [1, 0, 5, 0, 7] >>> dup_from_dict({}, ZZ) [] """ if not f: return [] n, h = max(f.keys()), [] if type(n) is int: for k in range(n, -1, -1): h.append(f.get(k, K.zero)) else: (n,) = n for k in range(n, -1, -1): h.append(f.get((k,), K.zero)) return dup_strip(h) def dup_from_raw_dict(f, K): """ Create a ``K[x]`` polynomial from a raw ``dict``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_from_raw_dict >>> dup_from_raw_dict({0: ZZ(7), 2: ZZ(5), 4: ZZ(1)}, ZZ) [1, 0, 5, 0, 7] """ if not f: return [] n, h = max(f.keys()), [] for k in range(n, -1, -1): h.append(f.get(k, K.zero)) return dup_strip(h) def dmp_from_dict(f, u, K): """ Create a ``K[X]`` polynomial from a ``dict``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_from_dict >>> dmp_from_dict({(0, 0): ZZ(3), (0, 1): ZZ(2), (2, 1): ZZ(1)}, 1, ZZ) [[1, 0], [], [2, 3]] >>> dmp_from_dict({}, 0, ZZ) [] """ if not u: return dup_from_dict(f, K) if not f: return dmp_zero(u) coeffs = {} for monom, coeff in f.items(): head, tail = monom[0], monom[1:] if head in coeffs: coeffs[head][tail] = coeff else: coeffs[head] = { tail: coeff } n, v, h = max(coeffs.keys()), u - 1, [] for k in range(n, -1, -1): coeff = coeffs.get(k) if coeff is not None: h.append(dmp_from_dict(coeff, v, K)) else: h.append(dmp_zero(v)) return dmp_strip(h, u) def dup_to_dict(f, K=None, zero=False): """ Convert ``K[x]`` polynomial to a ``dict``. Examples ======== >>> from sympy.polys.densebasic import dup_to_dict >>> dup_to_dict([1, 0, 5, 0, 7]) {(0,): 7, (2,): 5, (4,): 1} >>> dup_to_dict([]) {} """ if not f and zero: return {(0,): K.zero} n, result = len(f) - 1, {} for k in range(0, n + 1): if f[n - k]: result[(k,)] = f[n - k] return result def dup_to_raw_dict(f, K=None, zero=False): """ Convert a ``K[x]`` polynomial to a raw ``dict``. Examples ======== >>> from sympy.polys.densebasic import dup_to_raw_dict >>> dup_to_raw_dict([1, 0, 5, 0, 7]) {0: 7, 2: 5, 4: 1} """ if not f and zero: return {0: K.zero} n, result = len(f) - 1, {} for k in range(0, n + 1): if f[n - k]: result[k] = f[n - k] return result def dmp_to_dict(f, u, K=None, zero=False): """ Convert a ``K[X]`` polynomial to a ``dict````. Examples ======== >>> from sympy.polys.densebasic import dmp_to_dict >>> dmp_to_dict([[1, 0], [], [2, 3]], 1) {(0, 0): 3, (0, 1): 2, (2, 1): 1} >>> dmp_to_dict([], 0) {} """ if not u: return dup_to_dict(f, K, zero=zero) if dmp_zero_p(f, u) and zero: return {(0,)*(u + 1): K.zero} n, v, result = dmp_degree(f, u), u - 1, {} if n == -oo: n = -1 for k in range(0, n + 1): h = dmp_to_dict(f[n - k], v) for exp, coeff in h.items(): result[(k,) + exp] = coeff return result def dmp_swap(f, i, j, u, K): """ Transform ``K[..x_i..x_j..]`` to ``K[..x_j..x_i..]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_swap >>> f = ZZ.map([[[2], [1, 0]], []]) >>> dmp_swap(f, 0, 1, 2, ZZ) [[[2], []], [[1, 0], []]] >>> dmp_swap(f, 1, 2, 2, ZZ) [[[1], [2, 0]], [[]]] >>> dmp_swap(f, 0, 2, 2, ZZ) [[[1, 0]], [[2, 0], []]] """ if i < 0 or j < 0 or i > u or j > u: raise IndexError("0 <= i < j <= %s expected" % u) elif i == j: return f F, H = dmp_to_dict(f, u), {} for exp, coeff in F.items(): H[exp[:i] + (exp[j],) + exp[i + 1:j] + (exp[i],) + exp[j + 1:]] = coeff return dmp_from_dict(H, u, K) def dmp_permute(f, P, u, K): """ Return a polynomial in ``K[x_{P(1)},..,x_{P(n)}]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_permute >>> f = ZZ.map([[[2], [1, 0]], []]) >>> dmp_permute(f, [1, 0, 2], 2, ZZ) [[[2], []], [[1, 0], []]] >>> dmp_permute(f, [1, 2, 0], 2, ZZ) [[[1], []], [[2, 0], []]] """ F, H = dmp_to_dict(f, u), {} for exp, coeff in F.items(): new_exp = [0]*len(exp) for e, p in zip(exp, P): new_exp[p] = e H[tuple(new_exp)] = coeff return dmp_from_dict(H, u, K) def dmp_nest(f, l, K): """ Return a multivariate value nested ``l``-levels. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_nest >>> dmp_nest([[ZZ(1)]], 2, ZZ) [[[[1]]]] """ if not isinstance(f, list): return dmp_ground(f, l) for i in range(l): f = [f] return f def dmp_raise(f, l, u, K): """ Return a multivariate polynomial raised ``l``-levels. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_raise >>> f = ZZ.map([[], [1, 2]]) >>> dmp_raise(f, 2, 1, ZZ) [[[[]]], [[[1]], [[2]]]] """ if not l: return f if not u: if not f: return dmp_zero(l) k = l - 1 return [ dmp_ground(c, k) for c in f ] v = u - 1 return [ dmp_raise(c, l, v, K) for c in f ] def dup_deflate(f, K): """ Map ``x**m`` to ``y`` in a polynomial in ``K[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_deflate >>> f = ZZ.map([1, 0, 0, 1, 0, 0, 1]) >>> dup_deflate(f, ZZ) (3, [1, 1, 1]) """ if dup_degree(f) <= 0: return 1, f g = 0 for i in range(len(f)): if not f[-i - 1]: continue g = igcd(g, i) if g == 1: return 1, f return g, f[::g] def dmp_deflate(f, u, K): """ Map ``x_i**m_i`` to ``y_i`` in a polynomial in ``K[X]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_deflate >>> f = ZZ.map([[1, 0, 0, 2], [], [3, 0, 0, 4]]) >>> dmp_deflate(f, 1, ZZ) ((2, 3), [[1, 2], [3, 4]]) """ if dmp_zero_p(f, u): return (1,)*(u + 1), f F = dmp_to_dict(f, u) B = [0]*(u + 1) for M in F.keys(): for i, m in enumerate(M): B[i] = igcd(B[i], m) for i, b in enumerate(B): if not b: B[i] = 1 B = tuple(B) if all(b == 1 for b in B): return B, f H = {} for A, coeff in F.items(): N = [ a // b for a, b in zip(A, B) ] H[tuple(N)] = coeff return B, dmp_from_dict(H, u, K) def dup_multi_deflate(polys, K): """ Map ``x**m`` to ``y`` in a set of polynomials in ``K[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_multi_deflate >>> f = ZZ.map([1, 0, 2, 0, 3]) >>> g = ZZ.map([4, 0, 0]) >>> dup_multi_deflate((f, g), ZZ) (2, ([1, 2, 3], [4, 0])) """ G = 0 for p in polys: if dup_degree(p) <= 0: return 1, polys g = 0 for i in range(len(p)): if not p[-i - 1]: continue g = igcd(g, i) if g == 1: return 1, polys G = igcd(G, g) return G, tuple([ p[::G] for p in polys ]) def dmp_multi_deflate(polys, u, K): """ Map ``x_i**m_i`` to ``y_i`` in a set of polynomials in ``K[X]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_multi_deflate >>> f = ZZ.map([[1, 0, 0, 2], [], [3, 0, 0, 4]]) >>> g = ZZ.map([[1, 0, 2], [], [3, 0, 4]]) >>> dmp_multi_deflate((f, g), 1, ZZ) ((2, 1), ([[1, 0, 0, 2], [3, 0, 0, 4]], [[1, 0, 2], [3, 0, 4]])) """ if not u: M, H = dup_multi_deflate(polys, K) return (M,), H F, B = [], [0]*(u + 1) for p in polys: f = dmp_to_dict(p, u) if not dmp_zero_p(p, u): for M in f.keys(): for i, m in enumerate(M): B[i] = igcd(B[i], m) F.append(f) for i, b in enumerate(B): if not b: B[i] = 1 B = tuple(B) if all(b == 1 for b in B): return B, polys H = [] for f in F: h = {} for A, coeff in f.items(): N = [ a // b for a, b in zip(A, B) ] h[tuple(N)] = coeff H.append(dmp_from_dict(h, u, K)) return B, tuple(H) def dup_inflate(f, m, K): """ Map ``y`` to ``x**m`` in a polynomial in ``K[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_inflate >>> f = ZZ.map([1, 1, 1]) >>> dup_inflate(f, 3, ZZ) [1, 0, 0, 1, 0, 0, 1] """ if m <= 0: raise IndexError("'m' must be positive, got %s" % m) if m == 1 or not f: return f result = [f[0]] for coeff in f[1:]: result.extend([K.zero]*(m - 1)) result.append(coeff) return result def _rec_inflate(g, M, v, i, K): """Recursive helper for :func:`dmp_inflate`.""" if not v: return dup_inflate(g, M[i], K) if M[i] <= 0: raise IndexError("all M[i] must be positive, got %s" % M[i]) w, j = v - 1, i + 1 g = [ _rec_inflate(c, M, w, j, K) for c in g ] result = [g[0]] for coeff in g[1:]: for _ in range(1, M[i]): result.append(dmp_zero(w)) result.append(coeff) return result def dmp_inflate(f, M, u, K): """ Map ``y_i`` to ``x_i**k_i`` in a polynomial in ``K[X]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_inflate >>> f = ZZ.map([[1, 2], [3, 4]]) >>> dmp_inflate(f, (2, 3), 1, ZZ) [[1, 0, 0, 2], [], [3, 0, 0, 4]] """ if not u: return dup_inflate(f, M[0], K) if all(m == 1 for m in M): return f else: return _rec_inflate(f, M, u, 0, K) def dmp_exclude(f, u, K): """ Exclude useless levels from ``f``. Return the levels excluded, the new excluded ``f``, and the new ``u``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_exclude >>> f = ZZ.map([[[1]], [[1], [2]]]) >>> dmp_exclude(f, 2, ZZ) ([2], [[1], [1, 2]], 1) """ if not u or dmp_ground_p(f, None, u): return [], f, u J, F = [], dmp_to_dict(f, u) for j in range(0, u + 1): for monom in F.keys(): if monom[j]: break else: J.append(j) if not J: return [], f, u f = {} for monom, coeff in F.items(): monom = list(monom) for j in reversed(J): del monom[j] f[tuple(monom)] = coeff u -= len(J) return J, dmp_from_dict(f, u, K), u def dmp_include(f, J, u, K): """ Include useless levels in ``f``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_include >>> f = ZZ.map([[1], [1, 2]]) >>> dmp_include(f, [2], 1, ZZ) [[[1]], [[1], [2]]] """ if not J: return f F, f = dmp_to_dict(f, u), {} for monom, coeff in F.items(): monom = list(monom) for j in J: monom.insert(j, 0) f[tuple(monom)] = coeff u += len(J) return dmp_from_dict(f, u, K) def dmp_inject(f, u, K, front=False): """ Convert ``f`` from ``K[X][Y]`` to ``K[X,Y]``. Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_inject >>> R, x,y = ring("x,y", ZZ) >>> dmp_inject([R(1), x + 2], 0, R.to_domain()) ([[[1]], [[1], [2]]], 2) >>> dmp_inject([R(1), x + 2], 0, R.to_domain(), front=True) ([[[1]], [[1, 2]]], 2) """ f, h = dmp_to_dict(f, u), {} v = K.ngens - 1 for f_monom, g in f.items(): g = g.to_dict() for g_monom, c in g.items(): if front: h[g_monom + f_monom] = c else: h[f_monom + g_monom] = c w = u + v + 1 return dmp_from_dict(h, w, K.dom), w def dmp_eject(f, u, K, front=False): """ Convert ``f`` from ``K[X,Y]`` to ``K[X][Y]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_eject >>> dmp_eject([[[1]], [[1], [2]]], 2, ZZ['x', 'y']) [1, x + 2] """ f, h = dmp_to_dict(f, u), {} n = K.ngens v = u - K.ngens + 1 for monom, c in f.items(): if front: g_monom, f_monom = monom[:n], monom[n:] else: g_monom, f_monom = monom[-n:], monom[:-n] if f_monom in h: h[f_monom][g_monom] = c else: h[f_monom] = {g_monom: c} for monom, c in h.items(): h[monom] = K(c) return dmp_from_dict(h, v - 1, K) def dup_terms_gcd(f, K): """ Remove GCD of terms from ``f`` in ``K[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_terms_gcd >>> f = ZZ.map([1, 0, 1, 0, 0]) >>> dup_terms_gcd(f, ZZ) (2, [1, 0, 1]) """ if dup_TC(f, K) or not f: return 0, f i = 0 for c in reversed(f): if not c: i += 1 else: break return i, f[:-i] def dmp_terms_gcd(f, u, K): """ Remove GCD of terms from ``f`` in ``K[X]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_terms_gcd >>> f = ZZ.map([[1, 0], [1, 0, 0], [], []]) >>> dmp_terms_gcd(f, 1, ZZ) ((2, 1), [[1], [1, 0]]) """ if dmp_ground_TC(f, u, K) or dmp_zero_p(f, u): return (0,)*(u + 1), f F = dmp_to_dict(f, u) G = monomial_min(*list(F.keys())) if all(g == 0 for g in G): return G, f f = {} for monom, coeff in F.items(): f[monomial_div(monom, G)] = coeff return G, dmp_from_dict(f, u, K) def _rec_list_terms(g, v, monom): """Recursive helper for :func:`dmp_list_terms`.""" d, terms = dmp_degree(g, v), [] if not v: for i, c in enumerate(g): if not c: continue terms.append((monom + (d - i,), c)) else: w = v - 1 for i, c in enumerate(g): terms.extend(_rec_list_terms(c, w, monom + (d - i,))) return terms def dmp_list_terms(f, u, K, order=None): """ List all non-zero terms from ``f`` in the given order ``order``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_list_terms >>> f = ZZ.map([[1, 1], [2, 3]]) >>> dmp_list_terms(f, 1, ZZ) [((1, 1), 1), ((1, 0), 1), ((0, 1), 2), ((0, 0), 3)] >>> dmp_list_terms(f, 1, ZZ, order='grevlex') [((1, 1), 1), ((1, 0), 1), ((0, 1), 2), ((0, 0), 3)] """ def sort(terms, O): return sorted(terms, key=lambda term: O(term[0]), reverse=True) terms = _rec_list_terms(f, u, ()) if not terms: return [((0,)*(u + 1), K.zero)] if order is None: return terms else: return sort(terms, monomial_key(order)) def dup_apply_pairs(f, g, h, args, K): """ Apply ``h`` to pairs of coefficients of ``f`` and ``g``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_apply_pairs >>> h = lambda x, y, z: 2*x + y - z >>> dup_apply_pairs([1, 2, 3], [3, 2, 1], h, (1,), ZZ) [4, 5, 6] """ n, m = len(f), len(g) if n != m: if n > m: g = [K.zero]*(n - m) + g else: f = [K.zero]*(m - n) + f result = [] for a, b in zip(f, g): result.append(h(a, b, *args)) return dup_strip(result) def dmp_apply_pairs(f, g, h, args, u, K): """ Apply ``h`` to pairs of coefficients of ``f`` and ``g``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dmp_apply_pairs >>> h = lambda x, y, z: 2*x + y - z >>> dmp_apply_pairs([[1], [2, 3]], [[3], [2, 1]], h, (1,), 1, ZZ) [[4], [5, 6]] """ if not u: return dup_apply_pairs(f, g, h, args, K) n, m, v = len(f), len(g), u - 1 if n != m: if n > m: g = dmp_zeros(n - m, v, K) + g else: f = dmp_zeros(m - n, v, K) + f result = [] for a, b in zip(f, g): result.append(dmp_apply_pairs(a, b, h, args, v, K)) return dmp_strip(result, u) def dup_slice(f, m, n, K): """Take a continuous subsequence of terms of ``f`` in ``K[x]``. """ k = len(f) if k >= m: M = k - m else: M = 0 if k >= n: N = k - n else: N = 0 f = f[N:M] if not f: return [] else: return f + [K.zero]*m def dmp_slice(f, m, n, u, K): """Take a continuous subsequence of terms of ``f`` in ``K[X]``. """ return dmp_slice_in(f, m, n, 0, u, K) def dmp_slice_in(f, m, n, j, u, K): """Take a continuous subsequence of terms of ``f`` in ``x_j`` in ``K[X]``. """ if j < 0 or j > u: raise IndexError("-%s <= j < %s expected, got %s" % (u, u, j)) if not u: return dup_slice(f, m, n, K) f, g = dmp_to_dict(f, u), {} for monom, coeff in f.items(): k = monom[j] if k < m or k >= n: monom = monom[:j] + (0,) + monom[j + 1:] if monom in g: g[monom] += coeff else: g[monom] = coeff return dmp_from_dict(g, u, K) def dup_random(n, a, b, K): """ Return a polynomial of degree ``n`` with coefficients in ``[a, b]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.densebasic import dup_random >>> dup_random(3, -10, 10, ZZ) #doctest: +SKIP [-2, -8, 9, -4] """ f = [ K.convert(random.randint(a, b)) for _ in range(0, n + 1) ] while not f[0]: f[0] = K.convert(random.randint(a, b)) return f

478cb99e950a6031218bafb4855728ca3d184a4853128921f27de3640dc2ab85

"""Algorithms for computing symbolic roots of polynomials. """ from __future__ import print_function, division import math from sympy.core import S, I, pi from sympy.core.compatibility import ordered, range, reduce from sympy.core.exprtools import factor_terms from sympy.core.function import _mexpand from sympy.core.logic import fuzzy_not from sympy.core.mul import expand_2arg, Mul from sympy.core.numbers import Rational, igcd, comp from sympy.core.power import Pow from sympy.core.relational import Eq from sympy.core.symbol import Dummy, Symbol, symbols from sympy.core.sympify import sympify from sympy.functions import exp, sqrt, im, cos, acos, Piecewise from sympy.functions.elementary.miscellaneous import root from sympy.ntheory import divisors, isprime, nextprime from sympy.polys.polyerrors import (PolynomialError, GeneratorsNeeded, DomainError) from sympy.polys.polyquinticconst import PolyQuintic from sympy.polys.polytools import Poly, cancel, factor, gcd_list, discriminant from sympy.polys.rationaltools import together from sympy.polys.specialpolys import cyclotomic_poly from sympy.simplify import simplify, powsimp from sympy.utilities import public def roots_linear(f): """Returns a list of roots of a linear polynomial.""" r = -f.nth(0)/f.nth(1) dom = f.get_domain() if not dom.is_Numerical: if dom.is_Composite: r = factor(r) else: r = simplify(r) return [r] def roots_quadratic(f): """Returns a list of roots of a quadratic polynomial. If the domain is ZZ then the roots will be sorted with negatives coming before positives. The ordering will be the same for any numerical coefficients as long as the assumptions tested are correct, otherwise the ordering will not be sorted (but will be canonical). """ a, b, c = f.all_coeffs() dom = f.get_domain() def _sqrt(d): # remove squares from square root since both will be represented # in the results; a similar thing is happening in roots() but # must be duplicated here because not all quadratics are binomials co = [] other = [] for di in Mul.make_args(d): if di.is_Pow and di.exp.is_Integer and di.exp % 2 == 0: co.append(Pow(di.base, di.exp//2)) else: other.append(di) if co: d = Mul(*other) co = Mul(*co) return co*sqrt(d) return sqrt(d) def _simplify(expr): if dom.is_Composite: return factor(expr) else: return simplify(expr) if c is S.Zero: r0, r1 = S.Zero, -b/a if not dom.is_Numerical: r1 = _simplify(r1) elif r1.is_negative: r0, r1 = r1, r0 elif b is S.Zero: r = -c/a if not dom.is_Numerical: r = _simplify(r) R = _sqrt(r) r0 = -R r1 = R else: d = b**2 - 4*a*c A = 2*a B = -b/A if not dom.is_Numerical: d = _simplify(d) B = _simplify(B) D = factor_terms(_sqrt(d)/A) r0 = B - D r1 = B + D if a.is_negative: r0, r1 = r1, r0 elif not dom.is_Numerical: r0, r1 = [expand_2arg(i) for i in (r0, r1)] return [r0, r1] def roots_cubic(f, trig=False): """Returns a list of roots of a cubic polynomial. References ========== [1] https://en.wikipedia.org/wiki/Cubic_function, General formula for roots, (accessed November 17, 2014). """ if trig: a, b, c, d = f.all_coeffs() p = (3*a*c - b**2)/3/a**2 q = (2*b**3 - 9*a*b*c + 27*a**2*d)/(27*a**3) D = 18*a*b*c*d - 4*b**3*d + b**2*c**2 - 4*a*c**3 - 27*a**2*d**2 if (D > 0) == True: rv = [] for k in range(3): rv.append(2*sqrt(-p/3)*cos(acos(3*q/2/p*sqrt(-3/p))/3 - k*2*pi/3)) return [i - b/3/a for i in rv] _, a, b, c = f.monic().all_coeffs() if c is S.Zero: x1, x2 = roots([1, a, b], multiple=True) return [x1, S.Zero, x2] p = b - a**2/3 q = c - a*b/3 + 2*a**3/27 pon3 = p/3 aon3 = a/3 u1 = None if p is S.Zero: if q is S.Zero: return [-aon3]*3 if q.is_real: if q.is_positive: u1 = -root(q, 3) elif q.is_negative: u1 = root(-q, 3) elif q is S.Zero: y1, y2 = roots([1, 0, p], multiple=True) return [tmp - aon3 for tmp in [y1, S.Zero, y2]] elif q.is_real and q.is_negative: u1 = -root(-q/2 + sqrt(q**2/4 + pon3**3), 3) coeff = I*sqrt(3)/2 if u1 is None: u1 = S(1) u2 = -S.Half + coeff u3 = -S.Half - coeff a, b, c, d = S(1), a, b, c D0 = b**2 - 3*a*c D1 = 2*b**3 - 9*a*b*c + 27*a**2*d C = root((D1 + sqrt(D1**2 - 4*D0**3))/2, 3) return [-(b + uk*C + D0/C/uk)/3/a for uk in [u1, u2, u3]] u2 = u1*(-S.Half + coeff) u3 = u1*(-S.Half - coeff) if p is S.Zero: return [u1 - aon3, u2 - aon3, u3 - aon3] soln = [ -u1 + pon3/u1 - aon3, -u2 + pon3/u2 - aon3, -u3 + pon3/u3 - aon3 ] return soln def _roots_quartic_euler(p, q, r, a): """ Descartes-Euler solution of the quartic equation Parameters ========== p, q, r: coefficients of ``x**4 + p*x**2 + q*x + r`` a: shift of the roots Notes ===== This is a helper function for ``roots_quartic``. Look for solutions of the form :: ``x1 = sqrt(R) - sqrt(A + B*sqrt(R))`` ``x2 = -sqrt(R) - sqrt(A - B*sqrt(R))`` ``x3 = -sqrt(R) + sqrt(A - B*sqrt(R))`` ``x4 = sqrt(R) + sqrt(A + B*sqrt(R))`` To satisfy the quartic equation one must have ``p = -2*(R + A); q = -4*B*R; r = (R - A)**2 - B**2*R`` so that ``R`` must satisfy the Descartes-Euler resolvent equation ``64*R**3 + 32*p*R**2 + (4*p**2 - 16*r)*R - q**2 = 0`` If the resolvent does not have a rational solution, return None; in that case it is likely that the Ferrari method gives a simpler solution. Examples ======== >>> from sympy import S >>> from sympy.polys.polyroots import _roots_quartic_euler >>> p, q, r = -S(64)/5, -S(512)/125, -S(1024)/3125 >>> _roots_quartic_euler(p, q, r, S(0))[0] -sqrt(32*sqrt(5)/125 + 16/5) + 4*sqrt(5)/5 """ # solve the resolvent equation x = Dummy('x') eq = 64*x**3 + 32*p*x**2 + (4*p**2 - 16*r)*x - q**2 xsols = list(roots(Poly(eq, x), cubics=False).keys()) xsols = [sol for sol in xsols if sol.is_rational and sol.is_nonzero] if not xsols: return None R = max(xsols) c1 = sqrt(R) B = -q*c1/(4*R) A = -R - p/2 c2 = sqrt(A + B) c3 = sqrt(A - B) return [c1 - c2 - a, -c1 - c3 - a, -c1 + c3 - a, c1 + c2 - a] def roots_quartic(f): r""" Returns a list of roots of a quartic polynomial. There are many references for solving quartic expressions available [1-5]. This reviewer has found that many of them require one to select from among 2 or more possible sets of solutions and that some solutions work when one is searching for real roots but don't work when searching for complex roots (though this is not always stated clearly). The following routine has been tested and found to be correct for 0, 2 or 4 complex roots. The quasisymmetric case solution [6] looks for quartics that have the form `x**4 + A*x**3 + B*x**2 + C*x + D = 0` where `(C/A)**2 = D`. Although no general solution that is always applicable for all coefficients is known to this reviewer, certain conditions are tested to determine the simplest 4 expressions that can be returned: 1) `f = c + a*(a**2/8 - b/2) == 0` 2) `g = d - a*(a*(3*a**2/256 - b/16) + c/4) = 0` 3) if `f != 0` and `g != 0` and `p = -d + a*c/4 - b**2/12` then a) `p == 0` b) `p != 0` Examples ======== >>> from sympy import Poly, symbols, I >>> from sympy.polys.polyroots import roots_quartic >>> r = roots_quartic(Poly('x**4-6*x**3+17*x**2-26*x+20')) >>> # 4 complex roots: 1+-I*sqrt(3), 2+-I >>> sorted(str(tmp.evalf(n=2)) for tmp in r) ['1.0 + 1.7*I', '1.0 - 1.7*I', '2.0 + 1.0*I', '2.0 - 1.0*I'] References ========== 1. http://mathforum.org/dr.math/faq/faq.cubic.equations.html 2. https://en.wikipedia.org/wiki/Quartic_function#Summary_of_Ferrari.27s_method 3. http://planetmath.org/encyclopedia/GaloisTheoreticDerivationOfTheQuarticFormula.html 4. http://staff.bath.ac.uk/masjhd/JHD-CA.pdf 5. http://www.albmath.org/files/Math_5713.pdf 6. http://www.statemaster.com/encyclopedia/Quartic-equation 7. eqworld.ipmnet.ru/en/solutions/ae/ae0108.pdf """ _, a, b, c, d = f.monic().all_coeffs() if not d: return [S.Zero] + roots([1, a, b, c], multiple=True) elif (c/a)**2 == d: x, m = f.gen, c/a g = Poly(x**2 + a*x + b - 2*m, x) z1, z2 = roots_quadratic(g) h1 = Poly(x**2 - z1*x + m, x) h2 = Poly(x**2 - z2*x + m, x) r1 = roots_quadratic(h1) r2 = roots_quadratic(h2) return r1 + r2 else: a2 = a**2 e = b - 3*a2/8 f = _mexpand(c + a*(a2/8 - b/2)) g = _mexpand(d - a*(a*(3*a2/256 - b/16) + c/4)) aon4 = a/4 if f is S.Zero: y1, y2 = [sqrt(tmp) for tmp in roots([1, e, g], multiple=True)] return [tmp - aon4 for tmp in [-y1, -y2, y1, y2]] if g is S.Zero: y = [S.Zero] + roots([1, 0, e, f], multiple=True) return [tmp - aon4 for tmp in y] else: # Descartes-Euler method, see [7] sols = _roots_quartic_euler(e, f, g, aon4) if sols: return sols # Ferrari method, see [1, 2] a2 = a**2 e = b - 3*a2/8 f = c + a*(a2/8 - b/2) g = d - a*(a*(3*a2/256 - b/16) + c/4) p = -e**2/12 - g q = -e**3/108 + e*g/3 - f**2/8 TH = Rational(1, 3) def _ans(y): w = sqrt(e + 2*y) arg1 = 3*e + 2*y arg2 = 2*f/w ans = [] for s in [-1, 1]: root = sqrt(-(arg1 + s*arg2)) for t in [-1, 1]: ans.append((s*w - t*root)/2 - aon4) return ans # p == 0 case y1 = -5*e/6 - q**TH if p.is_zero: return _ans(y1) # if p != 0 then u below is not 0 root = sqrt(q**2/4 + p**3/27) r = -q/2 + root # or -q/2 - root u = r**TH # primary root of solve(x**3 - r, x) y2 = -5*e/6 + u - p/u/3 if fuzzy_not(p.is_zero): return _ans(y2) # sort it out once they know the values of the coefficients return [Piecewise((a1, Eq(p, 0)), (a2, True)) for a1, a2 in zip(_ans(y1), _ans(y2))] def roots_binomial(f): """Returns a list of roots of a binomial polynomial. If the domain is ZZ then the roots will be sorted with negatives coming before positives. The ordering will be the same for any numerical coefficients as long as the assumptions tested are correct, otherwise the ordering will not be sorted (but will be canonical). """ n = f.degree() a, b = f.nth(n), f.nth(0) base = -cancel(b/a) alpha = root(base, n) if alpha.is_number: alpha = alpha.expand(complex=True) # define some parameters that will allow us to order the roots. # If the domain is ZZ this is guaranteed to return roots sorted # with reals before non-real roots and non-real sorted according # to real part and imaginary part, e.g. -1, 1, -1 + I, 2 - I neg = base.is_negative even = n % 2 == 0 if neg: if even == True and (base + 1).is_positive: big = True else: big = False # get the indices in the right order so the computed # roots will be sorted when the domain is ZZ ks = [] imax = n//2 if even: ks.append(imax) imax -= 1 if not neg: ks.append(0) for i in range(imax, 0, -1): if neg: ks.extend([i, -i]) else: ks.extend([-i, i]) if neg: ks.append(0) if big: for i in range(0, len(ks), 2): pair = ks[i: i + 2] pair = list(reversed(pair)) # compute the roots roots, d = [], 2*I*pi/n for k in ks: zeta = exp(k*d).expand(complex=True) roots.append((alpha*zeta).expand(power_base=False)) return roots def _inv_totient_estimate(m): """ Find ``(L, U)`` such that ``L <= phi^-1(m) <= U``. Examples ======== >>> from sympy.polys.polyroots import _inv_totient_estimate >>> _inv_totient_estimate(192) (192, 840) >>> _inv_totient_estimate(400) (400, 1750) """ primes = [ d + 1 for d in divisors(m) if isprime(d + 1) ] a, b = 1, 1 for p in primes: a *= p b *= p - 1 L = m U = int(math.ceil(m*(float(a)/b))) P = p = 2 primes = [] while P <= U: p = nextprime(p) primes.append(p) P *= p P //= p b = 1 for p in primes[:-1]: b *= p - 1 U = int(math.ceil(m*(float(P)/b))) return L, U def roots_cyclotomic(f, factor=False): """Compute roots of cyclotomic polynomials. """ L, U = _inv_totient_estimate(f.degree()) for n in range(L, U + 1): g = cyclotomic_poly(n, f.gen, polys=True) if f == g: break else: # pragma: no cover raise RuntimeError("failed to find index of a cyclotomic polynomial") roots = [] if not factor: # get the indices in the right order so the computed # roots will be sorted h = n//2 ks = [i for i in range(1, n + 1) if igcd(i, n) == 1] ks.sort(key=lambda x: (x, -1) if x <= h else (abs(x - n), 1)) d = 2*I*pi/n for k in reversed(ks): roots.append(exp(k*d).expand(complex=True)) else: g = Poly(f, extension=root(-1, n)) for h, _ in ordered(g.factor_list()[1]): roots.append(-h.TC()) return roots def roots_quintic(f): """ Calculate exact roots of a solvable quintic """ result = [] coeff_5, coeff_4, p, q, r, s = f.all_coeffs() # Eqn must be of the form x^5 + px^3 + qx^2 + rx + s if coeff_4: return result if coeff_5 != 1: l = [p/coeff_5, q/coeff_5, r/coeff_5, s/coeff_5] if not all(coeff.is_Rational for coeff in l): return result f = Poly(f/coeff_5) quintic = PolyQuintic(f) # Eqn standardized. Algo for solving starts here if not f.is_irreducible: return result f20 = quintic.f20 # Check if f20 has linear factors over domain Z if f20.is_irreducible: return result # Now, we know that f is solvable for _factor in f20.factor_list()[1]: if _factor[0].is_linear: theta = _factor[0].root(0) break d = discriminant(f) delta = sqrt(d) # zeta = a fifth root of unity zeta1, zeta2, zeta3, zeta4 = quintic.zeta T = quintic.T(theta, d) tol = S(1e-10) alpha = T[1] + T[2]*delta alpha_bar = T[1] - T[2]*delta beta = T[3] + T[4]*delta beta_bar = T[3] - T[4]*delta disc = alpha**2 - 4*beta disc_bar = alpha_bar**2 - 4*beta_bar l0 = quintic.l0(theta) l1 = _quintic_simplify((-alpha + sqrt(disc)) / S(2)) l4 = _quintic_simplify((-alpha - sqrt(disc)) / S(2)) l2 = _quintic_simplify((-alpha_bar + sqrt(disc_bar)) / S(2)) l3 = _quintic_simplify((-alpha_bar - sqrt(disc_bar)) / S(2)) order = quintic.order(theta, d) test = (order*delta.n()) - ( (l1.n() - l4.n())*(l2.n() - l3.n()) ) # Comparing floats if not comp(test, 0, tol): l2, l3 = l3, l2 # Now we have correct order of l's R1 = l0 + l1*zeta1 + l2*zeta2 + l3*zeta3 + l4*zeta4 R2 = l0 + l3*zeta1 + l1*zeta2 + l4*zeta3 + l2*zeta4 R3 = l0 + l2*zeta1 + l4*zeta2 + l1*zeta3 + l3*zeta4 R4 = l0 + l4*zeta1 + l3*zeta2 + l2*zeta3 + l1*zeta4 Res = [None, [None]*5, [None]*5, [None]*5, [None]*5] Res_n = [None, [None]*5, [None]*5, [None]*5, [None]*5] sol = Symbol('sol') # Simplifying improves performance a lot for exact expressions R1 = _quintic_simplify(R1) R2 = _quintic_simplify(R2) R3 = _quintic_simplify(R3) R4 = _quintic_simplify(R4) # Solve imported here. Causing problems if imported as 'solve' # and hence the changed name from sympy.solvers.solvers import solve as _solve a, b = symbols('a b', cls=Dummy) _sol = _solve( sol**5 - a - I*b, sol) for i in range(5): _sol[i] = factor(_sol[i]) R1 = R1.as_real_imag() R2 = R2.as_real_imag() R3 = R3.as_real_imag() R4 = R4.as_real_imag() for i, currentroot in enumerate(_sol): Res[1][i] = _quintic_simplify(currentroot.subs({ a: R1[0], b: R1[1] })) Res[2][i] = _quintic_simplify(currentroot.subs({ a: R2[0], b: R2[1] })) Res[3][i] = _quintic_simplify(currentroot.subs({ a: R3[0], b: R3[1] })) Res[4][i] = _quintic_simplify(currentroot.subs({ a: R4[0], b: R4[1] })) for i in range(1, 5): for j in range(5): Res_n[i][j] = Res[i][j].n() Res[i][j] = _quintic_simplify(Res[i][j]) r1 = Res[1][0] r1_n = Res_n[1][0] for i in range(5): if comp(im(r1_n*Res_n[4][i]), 0, tol): r4 = Res[4][i] break u, v = quintic.uv(theta, d) # Now we have various Res values. Each will be a list of five # values. We have to pick one r value from those five for each Res u, v = quintic.uv(theta, d) testplus = (u + v*delta*sqrt(5)).n() testminus = (u - v*delta*sqrt(5)).n() # Evaluated numbers suffixed with _n # We will use evaluated numbers for calculation. Much faster. r4_n = r4.n() r2 = r3 = None for i in range(5): r2temp_n = Res_n[2][i] for j in range(5): # Again storing away the exact number and using # evaluated numbers in computations r3temp_n = Res_n[3][j] if (comp((r1_n*r2temp_n**2 + r4_n*r3temp_n**2 - testplus).n(), 0, tol) and comp((r3temp_n*r1_n**2 + r2temp_n*r4_n**2 - testminus).n(), 0, tol)): r2 = Res[2][i] r3 = Res[3][j] break if r2: break # Now, we have r's so we can get roots x1 = (r1 + r2 + r3 + r4)/5 x2 = (r1*zeta4 + r2*zeta3 + r3*zeta2 + r4*zeta1)/5 x3 = (r1*zeta3 + r2*zeta1 + r3*zeta4 + r4*zeta2)/5 x4 = (r1*zeta2 + r2*zeta4 + r3*zeta1 + r4*zeta3)/5 x5 = (r1*zeta1 + r2*zeta2 + r3*zeta3 + r4*zeta4)/5 result = [x1, x2, x3, x4, x5] # Now check if solutions are distinct saw = set() for r in result: r = r.n(2) if r in saw: # Roots were identical. Abort, return [] # and fall back to usual solve return [] saw.add(r) return result def _quintic_simplify(expr): expr = powsimp(expr) expr = cancel(expr) return together(expr) def _integer_basis(poly): """Compute coefficient basis for a polynomial over integers. Returns the integer ``div`` such that substituting ``x = div*y`` ``p(x) = m*q(y)`` where the coefficients of ``q`` are smaller than those of ``p``. For example ``x**5 + 512*x + 1024 = 0`` with ``div = 4`` becomes ``y**5 + 2*y + 1 = 0`` Returns the integer ``div`` or ``None`` if there is no possible scaling. Examples ======== >>> from sympy.polys import Poly >>> from sympy.abc import x >>> from sympy.polys.polyroots import _integer_basis >>> p = Poly(x**5 + 512*x + 1024, x, domain='ZZ') >>> _integer_basis(p) 4 """ monoms, coeffs = list(zip(*poly.terms())) monoms, = list(zip(*monoms)) coeffs = list(map(abs, coeffs)) if coeffs[0] < coeffs[-1]: coeffs = list(reversed(coeffs)) n = monoms[0] monoms = [n - i for i in reversed(monoms)] else: return None monoms = monoms[:-1] coeffs = coeffs[:-1] divs = reversed(divisors(gcd_list(coeffs))[1:]) try: div = next(divs) except StopIteration: return None while True: for monom, coeff in zip(monoms, coeffs): if coeff % div**monom != 0: try: div = next(divs) except StopIteration: return None else: break else: return div def preprocess_roots(poly): """Try to get rid of symbolic coefficients from ``poly``. """ coeff = S.One poly_func = poly.func try: _, poly = poly.clear_denoms(convert=True) except DomainError: return coeff, poly poly = poly.primitive()[1] poly = poly.retract() # TODO: This is fragile. Figure out how to make this independent of construct_domain(). if poly.get_domain().is_Poly and all(c.is_term for c in poly.rep.coeffs()): poly = poly.inject() strips = list(zip(*poly.monoms())) gens = list(poly.gens[1:]) base, strips = strips[0], strips[1:] for gen, strip in zip(list(gens), strips): reverse = False if strip[0] < strip[-1]: strip = reversed(strip) reverse = True ratio = None for a, b in zip(base, strip): if not a and not b: continue elif not a or not b: break elif b % a != 0: break else: _ratio = b // a if ratio is None: ratio = _ratio elif ratio != _ratio: break else: if reverse: ratio = -ratio poly = poly.eval(gen, 1) coeff *= gen**(-ratio) gens.remove(gen) if gens: poly = poly.eject(*gens) if poly.is_univariate and poly.get_domain().is_ZZ: basis = _integer_basis(poly) if basis is not None: n = poly.degree() def func(k, coeff): return coeff//basis**(n - k[0]) poly = poly.termwise(func) coeff *= basis if not isinstance(poly, poly_func): poly = poly_func(poly) return coeff, poly @public def roots(f, *gens, **flags): """ Computes symbolic roots of a univariate polynomial. Given a univariate polynomial f with symbolic coefficients (or a list of the polynomial's coefficients), returns a dictionary with its roots and their multiplicities. Only roots expressible via radicals will be returned. To get a complete set of roots use RootOf class or numerical methods instead. By default cubic and quartic formulas are used in the algorithm. To disable them because of unreadable output set ``cubics=False`` or ``quartics=False`` respectively. If cubic roots are real but are expressed in terms of complex numbers (casus irreducibilis [1]) the ``trig`` flag can be set to True to have the solutions returned in terms of cosine and inverse cosine functions. To get roots from a specific domain set the ``filter`` flag with one of the following specifiers: Z, Q, R, I, C. By default all roots are returned (this is equivalent to setting ``filter='C'``). By default a dictionary is returned giving a compact result in case of multiple roots. However to get a list containing all those roots set the ``multiple`` flag to True; the list will have identical roots appearing next to each other in the result. (For a given Poly, the all_roots method will give the roots in sorted numerical order.) Examples ======== >>> from sympy import Poly, roots >>> from sympy.abc import x, y >>> roots(x**2 - 1, x) {-1: 1, 1: 1} >>> p = Poly(x**2-1, x) >>> roots(p) {-1: 1, 1: 1} >>> p = Poly(x**2-y, x, y) >>> roots(Poly(p, x)) {-sqrt(y): 1, sqrt(y): 1} >>> roots(x**2 - y, x) {-sqrt(y): 1, sqrt(y): 1} >>> roots([1, 0, -1]) {-1: 1, 1: 1} References ========== .. [1] https://en.wikipedia.org/wiki/Cubic_function#Trigonometric_.28and_hyperbolic.29_method """ from sympy.polys.polytools import to_rational_coeffs flags = dict(flags) auto = flags.pop('auto', True) cubics = flags.pop('cubics', True) trig = flags.pop('trig', False) quartics = flags.pop('quartics', True) quintics = flags.pop('quintics', False) multiple = flags.pop('multiple', False) filter = flags.pop('filter', None) predicate = flags.pop('predicate', None) if isinstance(f, list): if gens: raise ValueError('redundant generators given') x = Dummy('x') poly, i = {}, len(f) - 1 for coeff in f: poly[i], i = sympify(coeff), i - 1 f = Poly(poly, x, field=True) else: try: f = Poly(f, *gens, **flags) if f.length == 2 and f.degree() != 1: # check for foo**n factors in the constant n = f.degree() npow_bases = [] others = [] expr = f.as_expr() con = expr.as_independent(*gens)[0] for p in Mul.make_args(con): if p.is_Pow and not p.exp % n: npow_bases.append(p.base**(p.exp/n)) else: others.append(p) if npow_bases: b = Mul(*npow_bases) B = Dummy() d = roots(Poly(expr - con + B**n*Mul(*others), *gens, **flags), *gens, **flags) rv = {} for k, v in d.items(): rv[k.subs(B, b)] = v return rv except GeneratorsNeeded: if multiple: return [] else: return {} if f.is_multivariate: raise PolynomialError('multivariate polynomials are not supported') def _update_dict(result, currentroot, k): if currentroot in result: result[currentroot] += k else: result[currentroot] = k def _try_decompose(f): """Find roots using functional decomposition. """ factors, roots = f.decompose(), [] for currentroot in _try_heuristics(factors[0]): roots.append(currentroot) for currentfactor in factors[1:]: previous, roots = list(roots), [] for currentroot in previous: g = currentfactor - Poly(currentroot, f.gen) for currentroot in _try_heuristics(g): roots.append(currentroot) return roots def _try_heuristics(f): """Find roots using formulas and some tricks. """ if f.is_ground: return [] if f.is_monomial: return [S(0)]*f.degree() if f.length() == 2: if f.degree() == 1: return list(map(cancel, roots_linear(f))) else: return roots_binomial(f) result = [] for i in [-1, 1]: if not f.eval(i): f = f.quo(Poly(f.gen - i, f.gen)) result.append(i) break n = f.degree() if n == 1: result += list(map(cancel, roots_linear(f))) elif n == 2: result += list(map(cancel, roots_quadratic(f))) elif f.is_cyclotomic: result += roots_cyclotomic(f) elif n == 3 and cubics: result += roots_cubic(f, trig=trig) elif n == 4 and quartics: result += roots_quartic(f) elif n == 5 and quintics: result += roots_quintic(f) return result (k,), f = f.terms_gcd() if not k: zeros = {} else: zeros = {S(0): k} coeff, f = preprocess_roots(f) if auto and f.get_domain().is_Ring: f = f.to_field() rescale_x = None translate_x = None result = {} if not f.is_ground: if not f.get_domain().is_Exact: for r in f.nroots(): _update_dict(result, r, 1) elif f.degree() == 1: result[roots_linear(f)[0]] = 1 elif f.length() == 2: roots_fun = roots_quadratic if f.degree() == 2 else roots_binomial for r in roots_fun(f): _update_dict(result, r, 1) else: _, factors = Poly(f.as_expr()).factor_list() if len(factors) == 1 and f.degree() == 2: for r in roots_quadratic(f): _update_dict(result, r, 1) else: if len(factors) == 1 and factors[0][1] == 1: if f.get_domain().is_EX: res = to_rational_coeffs(f) if res: if res[0] is None: translate_x, f = res[2:] else: rescale_x, f = res[1], res[-1] result = roots(f) if not result: for currentroot in _try_decompose(f): _update_dict(result, currentroot, 1) else: for r in _try_heuristics(f): _update_dict(result, r, 1) else: for currentroot in _try_decompose(f): _update_dict(result, currentroot, 1) else: for currentfactor, k in factors: for r in _try_heuristics(Poly(currentfactor, f.gen, field=True)): _update_dict(result, r, k) if coeff is not S.One: _result, result, = result, {} for currentroot, k in _result.items(): result[coeff*currentroot] = k result.update(zeros) if filter not in [None, 'C']: handlers = { 'Z': lambda r: r.is_Integer, 'Q': lambda r: r.is_Rational, 'R': lambda r: r.is_real, 'I': lambda r: r.is_imaginary, } try: query = handlers[filter] except KeyError: raise ValueError("Invalid filter: %s" % filter) for zero in dict(result).keys(): if not query(zero): del result[zero] if predicate is not None: for zero in dict(result).keys(): if not predicate(zero): del result[zero] if rescale_x: result1 = {} for k, v in result.items(): result1[k*rescale_x] = v result = result1 if translate_x: result1 = {} for k, v in result.items(): result1[k + translate_x] = v result = result1 if not multiple: return result else: zeros = [] for zero in ordered(result): zeros.extend([zero]*result[zero]) return zeros def root_factors(f, *gens, **args): """ Returns all factors of a univariate polynomial. Examples ======== >>> from sympy.abc import x, y >>> from sympy.polys.polyroots import root_factors >>> root_factors(x**2 - y, x) [x - sqrt(y), x + sqrt(y)] """ args = dict(args) filter = args.pop('filter', None) F = Poly(f, *gens, **args) if not F.is_Poly: return [f] if F.is_multivariate: raise ValueError('multivariate polynomials are not supported') x = F.gens[0] zeros = roots(F, filter=filter) if not zeros: factors = [F] else: factors, N = [], 0 for r, n in ordered(zeros.items()): factors, N = factors + [Poly(x - r, x)]*n, N + n if N < F.degree(): G = reduce(lambda p, q: p*q, factors) factors.append(F.quo(G)) if not isinstance(f, Poly): factors = [ f.as_expr() for f in factors ] return factors

1f9af2ea3c618f461ab67594a80a1f3b1304b2782f62e73d9b8de2486b31227b

"""Arithmetics for dense recursive polynomials in ``K[x]`` or ``K[X]``. """ from __future__ import print_function, division from sympy.core.compatibility import range from sympy.polys.densebasic import ( dup_slice, dup_LC, dmp_LC, dup_degree, dmp_degree, dup_strip, dmp_strip, dmp_zero_p, dmp_zero, dmp_one_p, dmp_one, dmp_ground, dmp_zeros) from sympy.polys.polyerrors import (ExactQuotientFailed, PolynomialDivisionFailed) def dup_add_term(f, c, i, K): """ Add ``c*x**i`` to ``f`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_add_term(x**2 - 1, ZZ(2), 4) 2*x**4 + x**2 - 1 """ if not c: return f n = len(f) m = n - i - 1 if i == n - 1: return dup_strip([f[0] + c] + f[1:]) else: if i >= n: return [c] + [K.zero]*(i - n) + f else: return f[:m] + [f[m] + c] + f[m + 1:] def dmp_add_term(f, c, i, u, K): """ Add ``c(x_2..x_u)*x_0**i`` to ``f`` in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_add_term(x*y + 1, 2, 2) 2*x**2 + x*y + 1 """ if not u: return dup_add_term(f, c, i, K) v = u - 1 if dmp_zero_p(c, v): return f n = len(f) m = n - i - 1 if i == n - 1: return dmp_strip([dmp_add(f[0], c, v, K)] + f[1:], u) else: if i >= n: return [c] + dmp_zeros(i - n, v, K) + f else: return f[:m] + [dmp_add(f[m], c, v, K)] + f[m + 1:] def dup_sub_term(f, c, i, K): """ Subtract ``c*x**i`` from ``f`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_sub_term(2*x**4 + x**2 - 1, ZZ(2), 4) x**2 - 1 """ if not c: return f n = len(f) m = n - i - 1 if i == n - 1: return dup_strip([f[0] - c] + f[1:]) else: if i >= n: return [-c] + [K.zero]*(i - n) + f else: return f[:m] + [f[m] - c] + f[m + 1:] def dmp_sub_term(f, c, i, u, K): """ Subtract ``c(x_2..x_u)*x_0**i`` from ``f`` in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_sub_term(2*x**2 + x*y + 1, 2, 2) x*y + 1 """ if not u: return dup_add_term(f, -c, i, K) v = u - 1 if dmp_zero_p(c, v): return f n = len(f) m = n - i - 1 if i == n - 1: return dmp_strip([dmp_sub(f[0], c, v, K)] + f[1:], u) else: if i >= n: return [dmp_neg(c, v, K)] + dmp_zeros(i - n, v, K) + f else: return f[:m] + [dmp_sub(f[m], c, v, K)] + f[m + 1:] def dup_mul_term(f, c, i, K): """ Multiply ``f`` by ``c*x**i`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_mul_term(x**2 - 1, ZZ(3), 2) 3*x**4 - 3*x**2 """ if not c or not f: return [] else: return [ cf * c for cf in f ] + [K.zero]*i def dmp_mul_term(f, c, i, u, K): """ Multiply ``f`` by ``c(x_2..x_u)*x_0**i`` in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_mul_term(x**2*y + x, 3*y, 2) 3*x**4*y**2 + 3*x**3*y """ if not u: return dup_mul_term(f, c, i, K) v = u - 1 if dmp_zero_p(f, u): return f if dmp_zero_p(c, v): return dmp_zero(u) else: return [ dmp_mul(cf, c, v, K) for cf in f ] + dmp_zeros(i, v, K) def dup_add_ground(f, c, K): """ Add an element of the ground domain to ``f``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_add_ground(x**3 + 2*x**2 + 3*x + 4, ZZ(4)) x**3 + 2*x**2 + 3*x + 8 """ return dup_add_term(f, c, 0, K) def dmp_add_ground(f, c, u, K): """ Add an element of the ground domain to ``f``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_add_ground(x**3 + 2*x**2 + 3*x + 4, ZZ(4)) x**3 + 2*x**2 + 3*x + 8 """ return dmp_add_term(f, dmp_ground(c, u - 1), 0, u, K) def dup_sub_ground(f, c, K): """ Subtract an element of the ground domain from ``f``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_sub_ground(x**3 + 2*x**2 + 3*x + 4, ZZ(4)) x**3 + 2*x**2 + 3*x """ return dup_sub_term(f, c, 0, K) def dmp_sub_ground(f, c, u, K): """ Subtract an element of the ground domain from ``f``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_sub_ground(x**3 + 2*x**2 + 3*x + 4, ZZ(4)) x**3 + 2*x**2 + 3*x """ return dmp_sub_term(f, dmp_ground(c, u - 1), 0, u, K) def dup_mul_ground(f, c, K): """ Multiply ``f`` by a constant value in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_mul_ground(x**2 + 2*x - 1, ZZ(3)) 3*x**2 + 6*x - 3 """ if not c or not f: return [] else: return [ cf * c for cf in f ] def dmp_mul_ground(f, c, u, K): """ Multiply ``f`` by a constant value in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_mul_ground(2*x + 2*y, ZZ(3)) 6*x + 6*y """ if not u: return dup_mul_ground(f, c, K) v = u - 1 return [ dmp_mul_ground(cf, c, v, K) for cf in f ] def dup_quo_ground(f, c, K): """ Quotient by a constant in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ, QQ >>> R, x = ring("x", ZZ) >>> R.dup_quo_ground(3*x**2 + 2, ZZ(2)) x**2 + 1 >>> R, x = ring("x", QQ) >>> R.dup_quo_ground(3*x**2 + 2, QQ(2)) 3/2*x**2 + 1 """ if not c: raise ZeroDivisionError('polynomial division') if not f: return f if K.is_Field: return [ K.quo(cf, c) for cf in f ] else: return [ cf // c for cf in f ] def dmp_quo_ground(f, c, u, K): """ Quotient by a constant in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ, QQ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_quo_ground(2*x**2*y + 3*x, ZZ(2)) x**2*y + x >>> R, x,y = ring("x,y", QQ) >>> R.dmp_quo_ground(2*x**2*y + 3*x, QQ(2)) x**2*y + 3/2*x """ if not u: return dup_quo_ground(f, c, K) v = u - 1 return [ dmp_quo_ground(cf, c, v, K) for cf in f ] def dup_exquo_ground(f, c, K): """ Exact quotient by a constant in ``K[x]``. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x = ring("x", QQ) >>> R.dup_exquo_ground(x**2 + 2, QQ(2)) 1/2*x**2 + 1 """ if not c: raise ZeroDivisionError('polynomial division') if not f: return f return [ K.exquo(cf, c) for cf in f ] def dmp_exquo_ground(f, c, u, K): """ Exact quotient by a constant in ``K[X]``. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x,y = ring("x,y", QQ) >>> R.dmp_exquo_ground(x**2*y + 2*x, QQ(2)) 1/2*x**2*y + x """ if not u: return dup_exquo_ground(f, c, K) v = u - 1 return [ dmp_exquo_ground(cf, c, v, K) for cf in f ] def dup_lshift(f, n, K): """ Efficiently multiply ``f`` by ``x**n`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_lshift(x**2 + 1, 2) x**4 + x**2 """ if not f: return f else: return f + [K.zero]*n def dup_rshift(f, n, K): """ Efficiently divide ``f`` by ``x**n`` in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_rshift(x**4 + x**2, 2) x**2 + 1 >>> R.dup_rshift(x**4 + x**2 + 2, 2) x**2 + 1 """ return f[:-n] def dup_abs(f, K): """ Make all coefficients positive in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_abs(x**2 - 1) x**2 + 1 """ return [ K.abs(coeff) for coeff in f ] def dmp_abs(f, u, K): """ Make all coefficients positive in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_abs(x**2*y - x) x**2*y + x """ if not u: return dup_abs(f, K) v = u - 1 return [ dmp_abs(cf, v, K) for cf in f ] def dup_neg(f, K): """ Negate a polynomial in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_neg(x**2 - 1) -x**2 + 1 """ return [ -coeff for coeff in f ] def dmp_neg(f, u, K): """ Negate a polynomial in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_neg(x**2*y - x) -x**2*y + x """ if not u: return dup_neg(f, K) v = u - 1 return [ dmp_neg(cf, v, K) for cf in f ] def dup_add(f, g, K): """ Add dense polynomials in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_add(x**2 - 1, x - 2) x**2 + x - 3 """ if not f: return g if not g: return f df = dup_degree(f) dg = dup_degree(g) if df == dg: return dup_strip([ a + b for a, b in zip(f, g) ]) else: k = abs(df - dg) if df > dg: h, f = f[:k], f[k:] else: h, g = g[:k], g[k:] return h + [ a + b for a, b in zip(f, g) ] def dmp_add(f, g, u, K): """ Add dense polynomials in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_add(x**2 + y, x**2*y + x) x**2*y + x**2 + x + y """ if not u: return dup_add(f, g, K) df = dmp_degree(f, u) if df < 0: return g dg = dmp_degree(g, u) if dg < 0: return f v = u - 1 if df == dg: return dmp_strip([ dmp_add(a, b, v, K) for a, b in zip(f, g) ], u) else: k = abs(df - dg) if df > dg: h, f = f[:k], f[k:] else: h, g = g[:k], g[k:] return h + [ dmp_add(a, b, v, K) for a, b in zip(f, g) ] def dup_sub(f, g, K): """ Subtract dense polynomials in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_sub(x**2 - 1, x - 2) x**2 - x + 1 """ if not f: return dup_neg(g, K) if not g: return f df = dup_degree(f) dg = dup_degree(g) if df == dg: return dup_strip([ a - b for a, b in zip(f, g) ]) else: k = abs(df - dg) if df > dg: h, f = f[:k], f[k:] else: h, g = dup_neg(g[:k], K), g[k:] return h + [ a - b for a, b in zip(f, g) ] def dmp_sub(f, g, u, K): """ Subtract dense polynomials in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_sub(x**2 + y, x**2*y + x) -x**2*y + x**2 - x + y """ if not u: return dup_sub(f, g, K) df = dmp_degree(f, u) if df < 0: return dmp_neg(g, u, K) dg = dmp_degree(g, u) if dg < 0: return f v = u - 1 if df == dg: return dmp_strip([ dmp_sub(a, b, v, K) for a, b in zip(f, g) ], u) else: k = abs(df - dg) if df > dg: h, f = f[:k], f[k:] else: h, g = dmp_neg(g[:k], u, K), g[k:] return h + [ dmp_sub(a, b, v, K) for a, b in zip(f, g) ] def dup_add_mul(f, g, h, K): """ Returns ``f + g*h`` where ``f, g, h`` are in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_add_mul(x**2 - 1, x - 2, x + 2) 2*x**2 - 5 """ return dup_add(f, dup_mul(g, h, K), K) def dmp_add_mul(f, g, h, u, K): """ Returns ``f + g*h`` where ``f, g, h`` are in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_add_mul(x**2 + y, x, x + 2) 2*x**2 + 2*x + y """ return dmp_add(f, dmp_mul(g, h, u, K), u, K) def dup_sub_mul(f, g, h, K): """ Returns ``f - g*h`` where ``f, g, h`` are in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_sub_mul(x**2 - 1, x - 2, x + 2) 3 """ return dup_sub(f, dup_mul(g, h, K), K) def dmp_sub_mul(f, g, h, u, K): """ Returns ``f - g*h`` where ``f, g, h`` are in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_sub_mul(x**2 + y, x, x + 2) -2*x + y """ return dmp_sub(f, dmp_mul(g, h, u, K), u, K) def dup_mul(f, g, K): """ Multiply dense polynomials in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_mul(x - 2, x + 2) x**2 - 4 """ if f == g: return dup_sqr(f, K) if not (f and g): return [] df = dup_degree(f) dg = dup_degree(g) n = max(df, dg) + 1 if n < 100: h = [] for i in range(0, df + dg + 1): coeff = K.zero for j in range(max(0, i - dg), min(df, i) + 1): coeff += f[j]*g[i - j] h.append(coeff) return dup_strip(h) else: # Use Karatsuba's algorithm (divide and conquer), see e.g.: # Joris van der Hoeven, Relax But Don't Be Too Lazy, # J. Symbolic Computation, 11 (2002), section 3.1.1. n2 = n//2 fl, gl = dup_slice(f, 0, n2, K), dup_slice(g, 0, n2, K) fh = dup_rshift(dup_slice(f, n2, n, K), n2, K) gh = dup_rshift(dup_slice(g, n2, n, K), n2, K) lo, hi = dup_mul(fl, gl, K), dup_mul(fh, gh, K) mid = dup_mul(dup_add(fl, fh, K), dup_add(gl, gh, K), K) mid = dup_sub(mid, dup_add(lo, hi, K), K) return dup_add(dup_add(lo, dup_lshift(mid, n2, K), K), dup_lshift(hi, 2*n2, K), K) def dmp_mul(f, g, u, K): """ Multiply dense polynomials in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_mul(x*y + 1, x) x**2*y + x """ if not u: return dup_mul(f, g, K) if f == g: return dmp_sqr(f, u, K) df = dmp_degree(f, u) if df < 0: return f dg = dmp_degree(g, u) if dg < 0: return g h, v = [], u - 1 for i in range(0, df + dg + 1): coeff = dmp_zero(v) for j in range(max(0, i - dg), min(df, i) + 1): coeff = dmp_add(coeff, dmp_mul(f[j], g[i - j], v, K), v, K) h.append(coeff) return dmp_strip(h, u) def dup_sqr(f, K): """ Square dense polynomials in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_sqr(x**2 + 1) x**4 + 2*x**2 + 1 """ df, h = len(f) - 1, [] for i in range(0, 2*df + 1): c = K.zero jmin = max(0, i - df) jmax = min(i, df) n = jmax - jmin + 1 jmax = jmin + n // 2 - 1 for j in range(jmin, jmax + 1): c += f[j]*f[i - j] c += c if n & 1: elem = f[jmax + 1] c += elem**2 h.append(c) return dup_strip(h) def dmp_sqr(f, u, K): """ Square dense polynomials in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_sqr(x**2 + x*y + y**2) x**4 + 2*x**3*y + 3*x**2*y**2 + 2*x*y**3 + y**4 """ if not u: return dup_sqr(f, K) df = dmp_degree(f, u) if df < 0: return f h, v = [], u - 1 for i in range(0, 2*df + 1): c = dmp_zero(v) jmin = max(0, i - df) jmax = min(i, df) n = jmax - jmin + 1 jmax = jmin + n // 2 - 1 for j in range(jmin, jmax + 1): c = dmp_add(c, dmp_mul(f[j], f[i - j], v, K), v, K) c = dmp_mul_ground(c, K(2), v, K) if n & 1: elem = dmp_sqr(f[jmax + 1], v, K) c = dmp_add(c, elem, v, K) h.append(c) return dmp_strip(h, u) def dup_pow(f, n, K): """ Raise ``f`` to the ``n``-th power in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_pow(x - 2, 3) x**3 - 6*x**2 + 12*x - 8 """ if not n: return [K.one] if n < 0: raise ValueError("can't raise polynomial to a negative power") if n == 1 or not f or f == [K.one]: return f g = [K.one] while True: n, m = n//2, n if m % 2: g = dup_mul(g, f, K) if not n: break f = dup_sqr(f, K) return g def dmp_pow(f, n, u, K): """ Raise ``f`` to the ``n``-th power in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_pow(x*y + 1, 3) x**3*y**3 + 3*x**2*y**2 + 3*x*y + 1 """ if not u: return dup_pow(f, n, K) if not n: return dmp_one(u, K) if n < 0: raise ValueError("can't raise polynomial to a negative power") if n == 1 or dmp_zero_p(f, u) or dmp_one_p(f, u, K): return f g = dmp_one(u, K) while True: n, m = n//2, n if m & 1: g = dmp_mul(g, f, u, K) if not n: break f = dmp_sqr(f, u, K) return g def dup_pdiv(f, g, K): """ Polynomial pseudo-division in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_pdiv(x**2 + 1, 2*x - 4) (2*x + 4, 20) """ df = dup_degree(f) dg = dup_degree(g) q, r, dr = [], f, df if not g: raise ZeroDivisionError("polynomial division") elif df < dg: return q, r N = df - dg + 1 lc_g = dup_LC(g, K) while True: lc_r = dup_LC(r, K) j, N = dr - dg, N - 1 Q = dup_mul_ground(q, lc_g, K) q = dup_add_term(Q, lc_r, j, K) R = dup_mul_ground(r, lc_g, K) G = dup_mul_term(g, lc_r, j, K) r = dup_sub(R, G, K) _dr, dr = dr, dup_degree(r) if dr < dg: break elif not (dr < _dr): raise PolynomialDivisionFailed(f, g, K) c = lc_g**N q = dup_mul_ground(q, c, K) r = dup_mul_ground(r, c, K) return q, r def dup_prem(f, g, K): """ Polynomial pseudo-remainder in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_prem(x**2 + 1, 2*x - 4) 20 """ df = dup_degree(f) dg = dup_degree(g) r, dr = f, df if not g: raise ZeroDivisionError("polynomial division") elif df < dg: return r N = df - dg + 1 lc_g = dup_LC(g, K) while True: lc_r = dup_LC(r, K) j, N = dr - dg, N - 1 R = dup_mul_ground(r, lc_g, K) G = dup_mul_term(g, lc_r, j, K) r = dup_sub(R, G, K) _dr, dr = dr, dup_degree(r) if dr < dg: break elif not (dr < _dr): raise PolynomialDivisionFailed(f, g, K) return dup_mul_ground(r, lc_g**N, K) def dup_pquo(f, g, K): """ Polynomial exact pseudo-quotient in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_pquo(x**2 - 1, 2*x - 2) 2*x + 2 >>> R.dup_pquo(x**2 + 1, 2*x - 4) 2*x + 4 """ return dup_pdiv(f, g, K)[0] def dup_pexquo(f, g, K): """ Polynomial pseudo-quotient in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_pexquo(x**2 - 1, 2*x - 2) 2*x + 2 >>> R.dup_pexquo(x**2 + 1, 2*x - 4) Traceback (most recent call last): ... ExactQuotientFailed: [2, -4] does not divide [1, 0, 1] """ q, r = dup_pdiv(f, g, K) if not r: return q else: raise ExactQuotientFailed(f, g) def dmp_pdiv(f, g, u, K): """ Polynomial pseudo-division in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_pdiv(x**2 + x*y, 2*x + 2) (2*x + 2*y - 2, -4*y + 4) """ if not u: return dup_pdiv(f, g, K) df = dmp_degree(f, u) dg = dmp_degree(g, u) if dg < 0: raise ZeroDivisionError("polynomial division") q, r, dr = dmp_zero(u), f, df if df < dg: return q, r N = df - dg + 1 lc_g = dmp_LC(g, K) while True: lc_r = dmp_LC(r, K) j, N = dr - dg, N - 1 Q = dmp_mul_term(q, lc_g, 0, u, K) q = dmp_add_term(Q, lc_r, j, u, K) R = dmp_mul_term(r, lc_g, 0, u, K) G = dmp_mul_term(g, lc_r, j, u, K) r = dmp_sub(R, G, u, K) _dr, dr = dr, dmp_degree(r, u) if dr < dg: break elif not (dr < _dr): raise PolynomialDivisionFailed(f, g, K) c = dmp_pow(lc_g, N, u - 1, K) q = dmp_mul_term(q, c, 0, u, K) r = dmp_mul_term(r, c, 0, u, K) return q, r def dmp_prem(f, g, u, K): """ Polynomial pseudo-remainder in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_prem(x**2 + x*y, 2*x + 2) -4*y + 4 """ if not u: return dup_prem(f, g, K) df = dmp_degree(f, u) dg = dmp_degree(g, u) if dg < 0: raise ZeroDivisionError("polynomial division") r, dr = f, df if df < dg: return r N = df - dg + 1 lc_g = dmp_LC(g, K) while True: lc_r = dmp_LC(r, K) j, N = dr - dg, N - 1 R = dmp_mul_term(r, lc_g, 0, u, K) G = dmp_mul_term(g, lc_r, j, u, K) r = dmp_sub(R, G, u, K) _dr, dr = dr, dmp_degree(r, u) if dr < dg: break elif not (dr < _dr): raise PolynomialDivisionFailed(f, g, K) c = dmp_pow(lc_g, N, u - 1, K) return dmp_mul_term(r, c, 0, u, K) def dmp_pquo(f, g, u, K): """ Polynomial exact pseudo-quotient in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = x**2 + x*y >>> g = 2*x + 2*y >>> h = 2*x + 2 >>> R.dmp_pquo(f, g) 2*x >>> R.dmp_pquo(f, h) 2*x + 2*y - 2 """ return dmp_pdiv(f, g, u, K)[0] def dmp_pexquo(f, g, u, K): """ Polynomial pseudo-quotient in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = x**2 + x*y >>> g = 2*x + 2*y >>> h = 2*x + 2 >>> R.dmp_pexquo(f, g) 2*x >>> R.dmp_pexquo(f, h) Traceback (most recent call last): ... ExactQuotientFailed: [[2], [2]] does not divide [[1], [1, 0], []] """ q, r = dmp_pdiv(f, g, u, K) if dmp_zero_p(r, u): return q else: raise ExactQuotientFailed(f, g) def dup_rr_div(f, g, K): """ Univariate division with remainder over a ring. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_rr_div(x**2 + 1, 2*x - 4) (0, x**2 + 1) """ df = dup_degree(f) dg = dup_degree(g) q, r, dr = [], f, df if not g: raise ZeroDivisionError("polynomial division") elif df < dg: return q, r lc_g = dup_LC(g, K) while True: lc_r = dup_LC(r, K) if lc_r % lc_g: break c = K.exquo(lc_r, lc_g) j = dr - dg q = dup_add_term(q, c, j, K) h = dup_mul_term(g, c, j, K) r = dup_sub(r, h, K) _dr, dr = dr, dup_degree(r) if dr < dg: break elif not (dr < _dr): raise PolynomialDivisionFailed(f, g, K) return q, r def dmp_rr_div(f, g, u, K): """ Multivariate division with remainder over a ring. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_rr_div(x**2 + x*y, 2*x + 2) (0, x**2 + x*y) """ if not u: return dup_rr_div(f, g, K) df = dmp_degree(f, u) dg = dmp_degree(g, u) if dg < 0: raise ZeroDivisionError("polynomial division") q, r, dr = dmp_zero(u), f, df if df < dg: return q, r lc_g, v = dmp_LC(g, K), u - 1 while True: lc_r = dmp_LC(r, K) c, R = dmp_rr_div(lc_r, lc_g, v, K) if not dmp_zero_p(R, v): break j = dr - dg q = dmp_add_term(q, c, j, u, K) h = dmp_mul_term(g, c, j, u, K) r = dmp_sub(r, h, u, K) _dr, dr = dr, dmp_degree(r, u) if dr < dg: break elif not (dr < _dr): raise PolynomialDivisionFailed(f, g, K) return q, r def dup_ff_div(f, g, K): """ Polynomial division with remainder over a field. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x = ring("x", QQ) >>> R.dup_ff_div(x**2 + 1, 2*x - 4) (1/2*x + 1, 5) """ df = dup_degree(f) dg = dup_degree(g) q, r, dr = [], f, df if not g: raise ZeroDivisionError("polynomial division") elif df < dg: return q, r lc_g = dup_LC(g, K) while True: lc_r = dup_LC(r, K) c = K.exquo(lc_r, lc_g) j = dr - dg q = dup_add_term(q, c, j, K) h = dup_mul_term(g, c, j, K) r = dup_sub(r, h, K) _dr, dr = dr, dup_degree(r) if dr < dg: break elif not (dr < _dr): raise PolynomialDivisionFailed(f, g, K) return q, r def dmp_ff_div(f, g, u, K): """ Polynomial division with remainder over a field. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x,y = ring("x,y", QQ) >>> R.dmp_ff_div(x**2 + x*y, 2*x + 2) (1/2*x + 1/2*y - 1/2, -y + 1) """ if not u: return dup_ff_div(f, g, K) df = dmp_degree(f, u) dg = dmp_degree(g, u) if dg < 0: raise ZeroDivisionError("polynomial division") q, r, dr = dmp_zero(u), f, df if df < dg: return q, r lc_g, v = dmp_LC(g, K), u - 1 while True: lc_r = dmp_LC(r, K) c, R = dmp_ff_div(lc_r, lc_g, v, K) if not dmp_zero_p(R, v): break j = dr - dg q = dmp_add_term(q, c, j, u, K) h = dmp_mul_term(g, c, j, u, K) r = dmp_sub(r, h, u, K) _dr, dr = dr, dmp_degree(r, u) if dr < dg: break elif not (dr < _dr): raise PolynomialDivisionFailed(f, g, K) return q, r def dup_div(f, g, K): """ Polynomial division with remainder in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ, QQ >>> R, x = ring("x", ZZ) >>> R.dup_div(x**2 + 1, 2*x - 4) (0, x**2 + 1) >>> R, x = ring("x", QQ) >>> R.dup_div(x**2 + 1, 2*x - 4) (1/2*x + 1, 5) """ if K.is_Field: return dup_ff_div(f, g, K) else: return dup_rr_div(f, g, K) def dup_rem(f, g, K): """ Returns polynomial remainder in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ, QQ >>> R, x = ring("x", ZZ) >>> R.dup_rem(x**2 + 1, 2*x - 4) x**2 + 1 >>> R, x = ring("x", QQ) >>> R.dup_rem(x**2 + 1, 2*x - 4) 5 """ return dup_div(f, g, K)[1] def dup_quo(f, g, K): """ Returns exact polynomial quotient in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ, QQ >>> R, x = ring("x", ZZ) >>> R.dup_quo(x**2 + 1, 2*x - 4) 0 >>> R, x = ring("x", QQ) >>> R.dup_quo(x**2 + 1, 2*x - 4) 1/2*x + 1 """ return dup_div(f, g, K)[0] def dup_exquo(f, g, K): """ Returns polynomial quotient in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_exquo(x**2 - 1, x - 1) x + 1 >>> R.dup_exquo(x**2 + 1, 2*x - 4) Traceback (most recent call last): ... ExactQuotientFailed: [2, -4] does not divide [1, 0, 1] """ q, r = dup_div(f, g, K) if not r: return q else: raise ExactQuotientFailed(f, g) def dmp_div(f, g, u, K): """ Polynomial division with remainder in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ, QQ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_div(x**2 + x*y, 2*x + 2) (0, x**2 + x*y) >>> R, x,y = ring("x,y", QQ) >>> R.dmp_div(x**2 + x*y, 2*x + 2) (1/2*x + 1/2*y - 1/2, -y + 1) """ if K.is_Field: return dmp_ff_div(f, g, u, K) else: return dmp_rr_div(f, g, u, K) def dmp_rem(f, g, u, K): """ Returns polynomial remainder in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ, QQ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_rem(x**2 + x*y, 2*x + 2) x**2 + x*y >>> R, x,y = ring("x,y", QQ) >>> R.dmp_rem(x**2 + x*y, 2*x + 2) -y + 1 """ return dmp_div(f, g, u, K)[1] def dmp_quo(f, g, u, K): """ Returns exact polynomial quotient in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ, QQ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_quo(x**2 + x*y, 2*x + 2) 0 >>> R, x,y = ring("x,y", QQ) >>> R.dmp_quo(x**2 + x*y, 2*x + 2) 1/2*x + 1/2*y - 1/2 """ return dmp_div(f, g, u, K)[0] def dmp_exquo(f, g, u, K): """ Returns polynomial quotient in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = x**2 + x*y >>> g = x + y >>> h = 2*x + 2 >>> R.dmp_exquo(f, g) x >>> R.dmp_exquo(f, h) Traceback (most recent call last): ... ExactQuotientFailed: [[2], [2]] does not divide [[1], [1, 0], []] """ q, r = dmp_div(f, g, u, K) if dmp_zero_p(r, u): return q else: raise ExactQuotientFailed(f, g) def dup_max_norm(f, K): """ Returns maximum norm of a polynomial in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_max_norm(-x**2 + 2*x - 3) 3 """ if not f: return K.zero else: return max(dup_abs(f, K)) def dmp_max_norm(f, u, K): """ Returns maximum norm of a polynomial in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_max_norm(2*x*y - x - 3) 3 """ if not u: return dup_max_norm(f, K) v = u - 1 return max([ dmp_max_norm(c, v, K) for c in f ]) def dup_l1_norm(f, K): """ Returns l1 norm of a polynomial in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_l1_norm(2*x**3 - 3*x**2 + 1) 6 """ if not f: return K.zero else: return sum(dup_abs(f, K)) def dmp_l1_norm(f, u, K): """ Returns l1 norm of a polynomial in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_l1_norm(2*x*y - x - 3) 6 """ if not u: return dup_l1_norm(f, K) v = u - 1 return sum([ dmp_l1_norm(c, v, K) for c in f ]) def dup_expand(polys, K): """ Multiply together several polynomials in ``K[x]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_expand([x**2 - 1, x, 2]) 2*x**3 - 2*x """ if not polys: return [K.one] f = polys[0] for g in polys[1:]: f = dup_mul(f, g, K) return f def dmp_expand(polys, u, K): """ Multiply together several polynomials in ``K[X]``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_expand([x**2 + y**2, x + 1]) x**3 + x**2 + x*y**2 + y**2 """ if not polys: return dmp_one(u, K) f = polys[0] for g in polys[1:]: f = dmp_mul(f, g, u, K) return f

c4653040a7f00b9c950c28f59732e579f7c83b5f57a969324dc9cf7b25fb3205

"""Dense univariate polynomials with coefficients in Galois fields. """ from __future__ import print_function, division from random import uniform from math import ceil as _ceil, sqrt as _sqrt from sympy.core.compatibility import SYMPY_INTS, range from sympy.core.mul import prod from sympy.ntheory import factorint from sympy.polys.polyconfig import query from sympy.polys.polyerrors import ExactQuotientFailed from sympy.polys.polyutils import _sort_factors def gf_crt(U, M, K=None): """ Chinese Remainder Theorem. Given a set of integer residues ``u_0,...,u_n`` and a set of co-prime integer moduli ``m_0,...,m_n``, returns an integer ``u``, such that ``u = u_i mod m_i`` for ``i = ``0,...,n``. Examples ======== Consider a set of residues ``U = [49, 76, 65]`` and a set of moduli ``M = [99, 97, 95]``. Then we have:: >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_crt >>> from sympy.ntheory.modular import solve_congruence >>> gf_crt([49, 76, 65], [99, 97, 95], ZZ) 639985 This is the correct result because:: >>> [639985 % m for m in [99, 97, 95]] [49, 76, 65] Note: this is a low-level routine with no error checking. See Also ======== sympy.ntheory.modular.crt : a higher level crt routine sympy.ntheory.modular.solve_congruence """ p = prod(M, start=K.one) v = K.zero for u, m in zip(U, M): e = p // m s, _, _ = K.gcdex(e, m) v += e*(u*s % m) return v % p def gf_crt1(M, K): """ First part of the Chinese Remainder Theorem. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_crt1 >>> gf_crt1([99, 97, 95], ZZ) (912285, [9215, 9405, 9603], [62, 24, 12]) """ E, S = [], [] p = prod(M, start=K.one) for m in M: E.append(p // m) S.append(K.gcdex(E[-1], m)[0] % m) return p, E, S def gf_crt2(U, M, p, E, S, K): """ Second part of the Chinese Remainder Theorem. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_crt2 >>> U = [49, 76, 65] >>> M = [99, 97, 95] >>> p = 912285 >>> E = [9215, 9405, 9603] >>> S = [62, 24, 12] >>> gf_crt2(U, M, p, E, S, ZZ) 639985 """ v = K.zero for u, m, e, s in zip(U, M, E, S): v += e*(u*s % m) return v % p def gf_int(a, p): """ Coerce ``a mod p`` to an integer in the range ``[-p/2, p/2]``. Examples ======== >>> from sympy.polys.galoistools import gf_int >>> gf_int(2, 7) 2 >>> gf_int(5, 7) -2 """ if a <= p // 2: return a else: return a - p def gf_degree(f): """ Return the leading degree of ``f``. Examples ======== >>> from sympy.polys.galoistools import gf_degree >>> gf_degree([1, 1, 2, 0]) 3 >>> gf_degree([]) -1 """ return len(f) - 1 def gf_LC(f, K): """ Return the leading coefficient of ``f``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_LC >>> gf_LC([3, 0, 1], ZZ) 3 """ if not f: return K.zero else: return f[0] def gf_TC(f, K): """ Return the trailing coefficient of ``f``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_TC >>> gf_TC([3, 0, 1], ZZ) 1 """ if not f: return K.zero else: return f[-1] def gf_strip(f): """ Remove leading zeros from ``f``. Examples ======== >>> from sympy.polys.galoistools import gf_strip >>> gf_strip([0, 0, 0, 3, 0, 1]) [3, 0, 1] """ if not f or f[0]: return f k = 0 for coeff in f: if coeff: break else: k += 1 return f[k:] def gf_trunc(f, p): """ Reduce all coefficients modulo ``p``. Examples ======== >>> from sympy.polys.galoistools import gf_trunc >>> gf_trunc([7, -2, 3], 5) [2, 3, 3] """ return gf_strip([ a % p for a in f ]) def gf_normal(f, p, K): """ Normalize all coefficients in ``K``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_normal >>> gf_normal([5, 10, 21, -3], 5, ZZ) [1, 2] """ return gf_trunc(list(map(K, f)), p) def gf_from_dict(f, p, K): """ Create a ``GF(p)[x]`` polynomial from a dict. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_from_dict >>> gf_from_dict({10: ZZ(4), 4: ZZ(33), 0: ZZ(-1)}, 5, ZZ) [4, 0, 0, 0, 0, 0, 3, 0, 0, 0, 4] """ n, h = max(f.keys()), [] if isinstance(n, SYMPY_INTS): for k in range(n, -1, -1): h.append(f.get(k, K.zero) % p) else: (n,) = n for k in range(n, -1, -1): h.append(f.get((k,), K.zero) % p) return gf_trunc(h, p) def gf_to_dict(f, p, symmetric=True): """ Convert a ``GF(p)[x]`` polynomial to a dict. Examples ======== >>> from sympy.polys.galoistools import gf_to_dict >>> gf_to_dict([4, 0, 0, 0, 0, 0, 3, 0, 0, 0, 4], 5) {0: -1, 4: -2, 10: -1} >>> gf_to_dict([4, 0, 0, 0, 0, 0, 3, 0, 0, 0, 4], 5, symmetric=False) {0: 4, 4: 3, 10: 4} """ n, result = gf_degree(f), {} for k in range(0, n + 1): if symmetric: a = gf_int(f[n - k], p) else: a = f[n - k] if a: result[k] = a return result def gf_from_int_poly(f, p): """ Create a ``GF(p)[x]`` polynomial from ``Z[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_from_int_poly >>> gf_from_int_poly([7, -2, 3], 5) [2, 3, 3] """ return gf_trunc(f, p) def gf_to_int_poly(f, p, symmetric=True): """ Convert a ``GF(p)[x]`` polynomial to ``Z[x]``. Examples ======== >>> from sympy.polys.galoistools import gf_to_int_poly >>> gf_to_int_poly([2, 3, 3], 5) [2, -2, -2] >>> gf_to_int_poly([2, 3, 3], 5, symmetric=False) [2, 3, 3] """ if symmetric: return [ gf_int(c, p) for c in f ] else: return f def gf_neg(f, p, K): """ Negate a polynomial in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_neg >>> gf_neg([3, 2, 1, 0], 5, ZZ) [2, 3, 4, 0] """ return [ -coeff % p for coeff in f ] def gf_add_ground(f, a, p, K): """ Compute ``f + a`` where ``f`` in ``GF(p)[x]`` and ``a`` in ``GF(p)``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_add_ground >>> gf_add_ground([3, 2, 4], 2, 5, ZZ) [3, 2, 1] """ if not f: a = a % p else: a = (f[-1] + a) % p if len(f) > 1: return f[:-1] + [a] if not a: return [] else: return [a] def gf_sub_ground(f, a, p, K): """ Compute ``f - a`` where ``f`` in ``GF(p)[x]`` and ``a`` in ``GF(p)``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_sub_ground >>> gf_sub_ground([3, 2, 4], 2, 5, ZZ) [3, 2, 2] """ if not f: a = -a % p else: a = (f[-1] - a) % p if len(f) > 1: return f[:-1] + [a] if not a: return [] else: return [a] def gf_mul_ground(f, a, p, K): """ Compute ``f * a`` where ``f`` in ``GF(p)[x]`` and ``a`` in ``GF(p)``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_mul_ground >>> gf_mul_ground([3, 2, 4], 2, 5, ZZ) [1, 4, 3] """ if not a: return [] else: return [ (a*b) % p for b in f ] def gf_quo_ground(f, a, p, K): """ Compute ``f/a`` where ``f`` in ``GF(p)[x]`` and ``a`` in ``GF(p)``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_quo_ground >>> gf_quo_ground(ZZ.map([3, 2, 4]), ZZ(2), 5, ZZ) [4, 1, 2] """ return gf_mul_ground(f, K.invert(a, p), p, K) def gf_add(f, g, p, K): """ Add polynomials in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_add >>> gf_add([3, 2, 4], [2, 2, 2], 5, ZZ) [4, 1] """ if not f: return g if not g: return f df = gf_degree(f) dg = gf_degree(g) if df == dg: return gf_strip([ (a + b) % p for a, b in zip(f, g) ]) else: k = abs(df - dg) if df > dg: h, f = f[:k], f[k:] else: h, g = g[:k], g[k:] return h + [ (a + b) % p for a, b in zip(f, g) ] def gf_sub(f, g, p, K): """ Subtract polynomials in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_sub >>> gf_sub([3, 2, 4], [2, 2, 2], 5, ZZ) [1, 0, 2] """ if not g: return f if not f: return gf_neg(g, p, K) df = gf_degree(f) dg = gf_degree(g) if df == dg: return gf_strip([ (a - b) % p for a, b in zip(f, g) ]) else: k = abs(df - dg) if df > dg: h, f = f[:k], f[k:] else: h, g = gf_neg(g[:k], p, K), g[k:] return h + [ (a - b) % p for a, b in zip(f, g) ] def gf_mul(f, g, p, K): """ Multiply polynomials in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_mul >>> gf_mul([3, 2, 4], [2, 2, 2], 5, ZZ) [1, 0, 3, 2, 3] """ df = gf_degree(f) dg = gf_degree(g) dh = df + dg h = [0]*(dh + 1) for i in range(0, dh + 1): coeff = K.zero for j in range(max(0, i - dg), min(i, df) + 1): coeff += f[j]*g[i - j] h[i] = coeff % p return gf_strip(h) def gf_sqr(f, p, K): """ Square polynomials in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_sqr >>> gf_sqr([3, 2, 4], 5, ZZ) [4, 2, 3, 1, 1] """ df = gf_degree(f) dh = 2*df h = [0]*(dh + 1) for i in range(0, dh + 1): coeff = K.zero jmin = max(0, i - df) jmax = min(i, df) n = jmax - jmin + 1 jmax = jmin + n // 2 - 1 for j in range(jmin, jmax + 1): coeff += f[j]*f[i - j] coeff += coeff if n & 1: elem = f[jmax + 1] coeff += elem**2 h[i] = coeff % p return gf_strip(h) def gf_add_mul(f, g, h, p, K): """ Returns ``f + g*h`` where ``f``, ``g``, ``h`` in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_add_mul >>> gf_add_mul([3, 2, 4], [2, 2, 2], [1, 4], 5, ZZ) [2, 3, 2, 2] """ return gf_add(f, gf_mul(g, h, p, K), p, K) def gf_sub_mul(f, g, h, p, K): """ Compute ``f - g*h`` where ``f``, ``g``, ``h`` in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_sub_mul >>> gf_sub_mul([3, 2, 4], [2, 2, 2], [1, 4], 5, ZZ) [3, 3, 2, 1] """ return gf_sub(f, gf_mul(g, h, p, K), p, K) def gf_expand(F, p, K): """ Expand results of :func:`factor` in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_expand >>> gf_expand([([3, 2, 4], 1), ([2, 2], 2), ([3, 1], 3)], 5, ZZ) [4, 3, 0, 3, 0, 1, 4, 1] """ if type(F) is tuple: lc, F = F else: lc = K.one g = [lc] for f, k in F: f = gf_pow(f, k, p, K) g = gf_mul(g, f, p, K) return g def gf_div(f, g, p, K): """ Division with remainder in ``GF(p)[x]``. Given univariate polynomials ``f`` and ``g`` with coefficients in a finite field with ``p`` elements, returns polynomials ``q`` and ``r`` (quotient and remainder) such that ``f = q*g + r``. Consider polynomials ``x**3 + x + 1`` and ``x**2 + x`` in GF(2):: >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_div, gf_add_mul >>> gf_div(ZZ.map([1, 0, 1, 1]), ZZ.map([1, 1, 0]), 2, ZZ) ([1, 1], [1]) As result we obtained quotient ``x + 1`` and remainder ``1``, thus:: >>> gf_add_mul(ZZ.map([1]), ZZ.map([1, 1]), ZZ.map([1, 1, 0]), 2, ZZ) [1, 0, 1, 1] References ========== .. [1] [Monagan93]_ .. [2] [Gathen99]_ """ df = gf_degree(f) dg = gf_degree(g) if not g: raise ZeroDivisionError("polynomial division") elif df < dg: return [], f inv = K.invert(g[0], p) h, dq, dr = list(f), df - dg, dg - 1 for i in range(0, df + 1): coeff = h[i] for j in range(max(0, dg - i), min(df - i, dr) + 1): coeff -= h[i + j - dg] * g[dg - j] if i <= dq: coeff *= inv h[i] = coeff % p return h[:dq + 1], gf_strip(h[dq + 1:]) def gf_rem(f, g, p, K): """ Compute polynomial remainder in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_rem >>> gf_rem(ZZ.map([1, 0, 1, 1]), ZZ.map([1, 1, 0]), 2, ZZ) [1] """ return gf_div(f, g, p, K)[1] def gf_quo(f, g, p, K): """ Compute exact quotient in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_quo >>> gf_quo(ZZ.map([1, 0, 1, 1]), ZZ.map([1, 1, 0]), 2, ZZ) [1, 1] >>> gf_quo(ZZ.map([1, 0, 3, 2, 3]), ZZ.map([2, 2, 2]), 5, ZZ) [3, 2, 4] """ df = gf_degree(f) dg = gf_degree(g) if not g: raise ZeroDivisionError("polynomial division") elif df < dg: return [] inv = K.invert(g[0], p) h, dq, dr = f[:], df - dg, dg - 1 for i in range(0, dq + 1): coeff = h[i] for j in range(max(0, dg - i), min(df - i, dr) + 1): coeff -= h[i + j - dg] * g[dg - j] h[i] = (coeff * inv) % p return h[:dq + 1] def gf_exquo(f, g, p, K): """ Compute polynomial quotient in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_exquo >>> gf_exquo(ZZ.map([1, 0, 3, 2, 3]), ZZ.map([2, 2, 2]), 5, ZZ) [3, 2, 4] >>> gf_exquo(ZZ.map([1, 0, 1, 1]), ZZ.map([1, 1, 0]), 2, ZZ) Traceback (most recent call last): ... ExactQuotientFailed: [1, 1, 0] does not divide [1, 0, 1, 1] """ q, r = gf_div(f, g, p, K) if not r: return q else: raise ExactQuotientFailed(f, g) def gf_lshift(f, n, K): """ Efficiently multiply ``f`` by ``x**n``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_lshift >>> gf_lshift([3, 2, 4], 4, ZZ) [3, 2, 4, 0, 0, 0, 0] """ if not f: return f else: return f + [K.zero]*n def gf_rshift(f, n, K): """ Efficiently divide ``f`` by ``x**n``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_rshift >>> gf_rshift([1, 2, 3, 4, 0], 3, ZZ) ([1, 2], [3, 4, 0]) """ if not n: return f, [] else: return f[:-n], f[-n:] def gf_pow(f, n, p, K): """ Compute ``f**n`` in ``GF(p)[x]`` using repeated squaring. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_pow >>> gf_pow([3, 2, 4], 3, 5, ZZ) [2, 4, 4, 2, 2, 1, 4] """ if not n: return [K.one] elif n == 1: return f elif n == 2: return gf_sqr(f, p, K) h = [K.one] while True: if n & 1: h = gf_mul(h, f, p, K) n -= 1 n >>= 1 if not n: break f = gf_sqr(f, p, K) return h def gf_frobenius_monomial_base(g, p, K): """ return the list of ``x**(i*p) mod g in Z_p`` for ``i = 0, .., n - 1`` where ``n = gf_degree(g)`` Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_frobenius_monomial_base >>> g = ZZ.map([1, 0, 2, 1]) >>> gf_frobenius_monomial_base(g, 5, ZZ) [[1], [4, 4, 2], [1, 2]] """ n = gf_degree(g) if n == 0: return [] b = [0]*n b[0] = [1] if p < n: for i in range(1, n): mon = gf_lshift(b[i - 1], p, K) b[i] = gf_rem(mon, g, p, K) elif n > 1: b[1] = gf_pow_mod([K.one, K.zero], p, g, p, K) for i in range(2, n): b[i] = gf_mul(b[i - 1], b[1], p, K) b[i] = gf_rem(b[i], g, p, K) return b def gf_frobenius_map(f, g, b, p, K): """ compute gf_pow_mod(f, p, g, p, K) using the Frobenius map Parameters ========== f, g : polynomials in ``GF(p)[x]`` b : frobenius monomial base p : prime number K : domain Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_frobenius_monomial_base, gf_frobenius_map >>> f = ZZ.map([2, 1 , 0, 1]) >>> g = ZZ.map([1, 0, 2, 1]) >>> p = 5 >>> b = gf_frobenius_monomial_base(g, p, ZZ) >>> r = gf_frobenius_map(f, g, b, p, ZZ) >>> gf_frobenius_map(f, g, b, p, ZZ) [4, 0, 3] """ m = gf_degree(g) if gf_degree(f) >= m: f = gf_rem(f, g, p, K) if not f: return [] n = gf_degree(f) sf = [f[-1]] for i in range(1, n + 1): v = gf_mul_ground(b[i], f[n - i], p, K) sf = gf_add(sf, v, p, K) return sf def _gf_pow_pnm1d2(f, n, g, b, p, K): """ utility function for ``gf_edf_zassenhaus`` Compute ``f**((p**n - 1) // 2)`` in ``GF(p)[x]/(g)`` ``f**((p**n - 1) // 2) = (f*f**p*...*f**(p**n - 1))**((p - 1) // 2)`` """ f = gf_rem(f, g, p, K) h = f r = f for i in range(1, n): h = gf_frobenius_map(h, g, b, p, K) r = gf_mul(r, h, p, K) r = gf_rem(r, g, p, K) res = gf_pow_mod(r, (p - 1)//2, g, p, K) return res def gf_pow_mod(f, n, g, p, K): """ Compute ``f**n`` in ``GF(p)[x]/(g)`` using repeated squaring. Given polynomials ``f`` and ``g`` in ``GF(p)[x]`` and a non-negative integer ``n``, efficiently computes ``f**n (mod g)`` i.e. the remainder of ``f**n`` from division by ``g``, using the repeated squaring algorithm. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_pow_mod >>> gf_pow_mod(ZZ.map([3, 2, 4]), 3, ZZ.map([1, 1]), 5, ZZ) [] References ========== .. [1] [Gathen99]_ """ if not n: return [K.one] elif n == 1: return gf_rem(f, g, p, K) elif n == 2: return gf_rem(gf_sqr(f, p, K), g, p, K) h = [K.one] while True: if n & 1: h = gf_mul(h, f, p, K) h = gf_rem(h, g, p, K) n -= 1 n >>= 1 if not n: break f = gf_sqr(f, p, K) f = gf_rem(f, g, p, K) return h def gf_gcd(f, g, p, K): """ Euclidean Algorithm in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_gcd >>> gf_gcd(ZZ.map([3, 2, 4]), ZZ.map([2, 2, 3]), 5, ZZ) [1, 3] """ while g: f, g = g, gf_rem(f, g, p, K) return gf_monic(f, p, K)[1] def gf_lcm(f, g, p, K): """ Compute polynomial LCM in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_lcm >>> gf_lcm(ZZ.map([3, 2, 4]), ZZ.map([2, 2, 3]), 5, ZZ) [1, 2, 0, 4] """ if not f or not g: return [] h = gf_quo(gf_mul(f, g, p, K), gf_gcd(f, g, p, K), p, K) return gf_monic(h, p, K)[1] def gf_cofactors(f, g, p, K): """ Compute polynomial GCD and cofactors in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_cofactors >>> gf_cofactors(ZZ.map([3, 2, 4]), ZZ.map([2, 2, 3]), 5, ZZ) ([1, 3], [3, 3], [2, 1]) """ if not f and not g: return ([], [], []) h = gf_gcd(f, g, p, K) return (h, gf_quo(f, h, p, K), gf_quo(g, h, p, K)) def gf_gcdex(f, g, p, K): """ Extended Euclidean Algorithm in ``GF(p)[x]``. Given polynomials ``f`` and ``g`` in ``GF(p)[x]``, computes polynomials ``s``, ``t`` and ``h``, such that ``h = gcd(f, g)`` and ``s*f + t*g = h``. The typical application of EEA is solving polynomial diophantine equations. Consider polynomials ``f = (x + 7) (x + 1)``, ``g = (x + 7) (x**2 + 1)`` in ``GF(11)[x]``. Application of Extended Euclidean Algorithm gives:: >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_gcdex, gf_mul, gf_add >>> s, t, g = gf_gcdex(ZZ.map([1, 8, 7]), ZZ.map([1, 7, 1, 7]), 11, ZZ) >>> s, t, g ([5, 6], [6], [1, 7]) As result we obtained polynomials ``s = 5*x + 6`` and ``t = 6``, and additionally ``gcd(f, g) = x + 7``. This is correct because:: >>> S = gf_mul(s, ZZ.map([1, 8, 7]), 11, ZZ) >>> T = gf_mul(t, ZZ.map([1, 7, 1, 7]), 11, ZZ) >>> gf_add(S, T, 11, ZZ) == [1, 7] True References ========== .. [1] [Gathen99]_ """ if not (f or g): return [K.one], [], [] p0, r0 = gf_monic(f, p, K) p1, r1 = gf_monic(g, p, K) if not f: return [], [K.invert(p1, p)], r1 if not g: return [K.invert(p0, p)], [], r0 s0, s1 = [K.invert(p0, p)], [] t0, t1 = [], [K.invert(p1, p)] while True: Q, R = gf_div(r0, r1, p, K) if not R: break (lc, r1), r0 = gf_monic(R, p, K), r1 inv = K.invert(lc, p) s = gf_sub_mul(s0, s1, Q, p, K) t = gf_sub_mul(t0, t1, Q, p, K) s1, s0 = gf_mul_ground(s, inv, p, K), s1 t1, t0 = gf_mul_ground(t, inv, p, K), t1 return s1, t1, r1 def gf_monic(f, p, K): """ Compute LC and a monic polynomial in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_monic >>> gf_monic(ZZ.map([3, 2, 4]), 5, ZZ) (3, [1, 4, 3]) """ if not f: return K.zero, [] else: lc = f[0] if K.is_one(lc): return lc, list(f) else: return lc, gf_quo_ground(f, lc, p, K) def gf_diff(f, p, K): """ Differentiate polynomial in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_diff >>> gf_diff([3, 2, 4], 5, ZZ) [1, 2] """ df = gf_degree(f) h, n = [K.zero]*df, df for coeff in f[:-1]: coeff *= K(n) coeff %= p if coeff: h[df - n] = coeff n -= 1 return gf_strip(h) def gf_eval(f, a, p, K): """ Evaluate ``f(a)`` in ``GF(p)`` using Horner scheme. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_eval >>> gf_eval([3, 2, 4], 2, 5, ZZ) 0 """ result = K.zero for c in f: result *= a result += c result %= p return result def gf_multi_eval(f, A, p, K): """ Evaluate ``f(a)`` for ``a`` in ``[a_1, ..., a_n]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_multi_eval >>> gf_multi_eval([3, 2, 4], [0, 1, 2, 3, 4], 5, ZZ) [4, 4, 0, 2, 0] """ return [ gf_eval(f, a, p, K) for a in A ] def gf_compose(f, g, p, K): """ Compute polynomial composition ``f(g)`` in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_compose >>> gf_compose([3, 2, 4], [2, 2, 2], 5, ZZ) [2, 4, 0, 3, 0] """ if len(g) <= 1: return gf_strip([gf_eval(f, gf_LC(g, K), p, K)]) if not f: return [] h = [f[0]] for c in f[1:]: h = gf_mul(h, g, p, K) h = gf_add_ground(h, c, p, K) return h def gf_compose_mod(g, h, f, p, K): """ Compute polynomial composition ``g(h)`` in ``GF(p)[x]/(f)``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_compose_mod >>> gf_compose_mod(ZZ.map([3, 2, 4]), ZZ.map([2, 2, 2]), ZZ.map([4, 3]), 5, ZZ) [4] """ if not g: return [] comp = [g[0]] for a in g[1:]: comp = gf_mul(comp, h, p, K) comp = gf_add_ground(comp, a, p, K) comp = gf_rem(comp, f, p, K) return comp def gf_trace_map(a, b, c, n, f, p, K): """ Compute polynomial trace map in ``GF(p)[x]/(f)``. Given a polynomial ``f`` in ``GF(p)[x]``, polynomials ``a``, ``b``, ``c`` in the quotient ring ``GF(p)[x]/(f)`` such that ``b = c**t (mod f)`` for some positive power ``t`` of ``p``, and a positive integer ``n``, returns a mapping:: a -> a**t**n, a + a**t + a**t**2 + ... + a**t**n (mod f) In factorization context, ``b = x**p mod f`` and ``c = x mod f``. This way we can efficiently compute trace polynomials in equal degree factorization routine, much faster than with other methods, like iterated Frobenius algorithm, for large degrees. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_trace_map >>> gf_trace_map([1, 2], [4, 4], [1, 1], 4, [3, 2, 4], 5, ZZ) ([1, 3], [1, 3]) References ========== .. [1] [Gathen92]_ """ u = gf_compose_mod(a, b, f, p, K) v = b if n & 1: U = gf_add(a, u, p, K) V = b else: U = a V = c n >>= 1 while n: u = gf_add(u, gf_compose_mod(u, v, f, p, K), p, K) v = gf_compose_mod(v, v, f, p, K) if n & 1: U = gf_add(U, gf_compose_mod(u, V, f, p, K), p, K) V = gf_compose_mod(v, V, f, p, K) n >>= 1 return gf_compose_mod(a, V, f, p, K), U def _gf_trace_map(f, n, g, b, p, K): """ utility for ``gf_edf_shoup`` """ f = gf_rem(f, g, p, K) h = f r = f for i in range(1, n): h = gf_frobenius_map(h, g, b, p, K) r = gf_add(r, h, p, K) r = gf_rem(r, g, p, K) return r def gf_random(n, p, K): """ Generate a random polynomial in ``GF(p)[x]`` of degree ``n``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_random >>> gf_random(10, 5, ZZ) #doctest: +SKIP [1, 2, 3, 2, 1, 1, 1, 2, 0, 4, 2] """ return [K.one] + [ K(int(uniform(0, p))) for i in range(0, n) ] def gf_irreducible(n, p, K): """ Generate random irreducible polynomial of degree ``n`` in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_irreducible >>> gf_irreducible(10, 5, ZZ) #doctest: +SKIP [1, 4, 2, 2, 3, 2, 4, 1, 4, 0, 4] """ while True: f = gf_random(n, p, K) if gf_irreducible_p(f, p, K): return f def gf_irred_p_ben_or(f, p, K): """ Ben-Or's polynomial irreducibility test over finite fields. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_irred_p_ben_or >>> gf_irred_p_ben_or(ZZ.map([1, 4, 2, 2, 3, 2, 4, 1, 4, 0, 4]), 5, ZZ) True >>> gf_irred_p_ben_or(ZZ.map([3, 2, 4]), 5, ZZ) False """ n = gf_degree(f) if n <= 1: return True _, f = gf_monic(f, p, K) if n < 5: H = h = gf_pow_mod([K.one, K.zero], p, f, p, K) for i in range(0, n//2): g = gf_sub(h, [K.one, K.zero], p, K) if gf_gcd(f, g, p, K) == [K.one]: h = gf_compose_mod(h, H, f, p, K) else: return False else: b = gf_frobenius_monomial_base(f, p, K) H = h = gf_frobenius_map([K.one, K.zero], f, b, p, K) for i in range(0, n//2): g = gf_sub(h, [K.one, K.zero], p, K) if gf_gcd(f, g, p, K) == [K.one]: h = gf_frobenius_map(h, f, b, p, K) else: return False return True def gf_irred_p_rabin(f, p, K): """ Rabin's polynomial irreducibility test over finite fields. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_irred_p_rabin >>> gf_irred_p_rabin(ZZ.map([1, 4, 2, 2, 3, 2, 4, 1, 4, 0, 4]), 5, ZZ) True >>> gf_irred_p_rabin(ZZ.map([3, 2, 4]), 5, ZZ) False """ n = gf_degree(f) if n <= 1: return True _, f = gf_monic(f, p, K) x = [K.one, K.zero] indices = { n//d for d in factorint(n) } b = gf_frobenius_monomial_base(f, p, K) h = b[1] for i in range(1, n): if i in indices: g = gf_sub(h, x, p, K) if gf_gcd(f, g, p, K) != [K.one]: return False h = gf_frobenius_map(h, f, b, p, K) return h == x _irred_methods = { 'ben-or': gf_irred_p_ben_or, 'rabin': gf_irred_p_rabin, } def gf_irreducible_p(f, p, K): """ Test irreducibility of a polynomial ``f`` in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_irreducible_p >>> gf_irreducible_p(ZZ.map([1, 4, 2, 2, 3, 2, 4, 1, 4, 0, 4]), 5, ZZ) True >>> gf_irreducible_p(ZZ.map([3, 2, 4]), 5, ZZ) False """ method = query('GF_IRRED_METHOD') if method is not None: irred = _irred_methods[method](f, p, K) else: irred = gf_irred_p_rabin(f, p, K) return irred def gf_sqf_p(f, p, K): """ Return ``True`` if ``f`` is square-free in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_sqf_p >>> gf_sqf_p(ZZ.map([3, 2, 4]), 5, ZZ) True >>> gf_sqf_p(ZZ.map([2, 4, 4, 2, 2, 1, 4]), 5, ZZ) False """ _, f = gf_monic(f, p, K) if not f: return True else: return gf_gcd(f, gf_diff(f, p, K), p, K) == [K.one] def gf_sqf_part(f, p, K): """ Return square-free part of a ``GF(p)[x]`` polynomial. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_sqf_part >>> gf_sqf_part(ZZ.map([1, 1, 3, 0, 1, 0, 2, 2, 1]), 5, ZZ) [1, 4, 3] """ _, sqf = gf_sqf_list(f, p, K) g = [K.one] for f, _ in sqf: g = gf_mul(g, f, p, K) return g def gf_sqf_list(f, p, K, all=False): """ Return the square-free decomposition of a ``GF(p)[x]`` polynomial. Given a polynomial ``f`` in ``GF(p)[x]``, returns the leading coefficient of ``f`` and a square-free decomposition ``f_1**e_1 f_2**e_2 ... f_k**e_k`` such that all ``f_i`` are monic polynomials and ``(f_i, f_j)`` for ``i != j`` are co-prime and ``e_1 ... e_k`` are given in increasing order. All trivial terms (i.e. ``f_i = 1``) aren't included in the output. Consider polynomial ``f = x**11 + 1`` over ``GF(11)[x]``:: >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import ( ... gf_from_dict, gf_diff, gf_sqf_list, gf_pow, ... ) ... # doctest: +NORMALIZE_WHITESPACE >>> f = gf_from_dict({11: ZZ(1), 0: ZZ(1)}, 11, ZZ) Note that ``f'(x) = 0``:: >>> gf_diff(f, 11, ZZ) [] This phenomenon doesn't happen in characteristic zero. However we can still compute square-free decomposition of ``f`` using ``gf_sqf()``:: >>> gf_sqf_list(f, 11, ZZ) (1, [([1, 1], 11)]) We obtained factorization ``f = (x + 1)**11``. This is correct because:: >>> gf_pow([1, 1], 11, 11, ZZ) == f True References ========== .. [1] [Geddes92]_ """ n, sqf, factors, r = 1, False, [], int(p) lc, f = gf_monic(f, p, K) if gf_degree(f) < 1: return lc, [] while True: F = gf_diff(f, p, K) if F != []: g = gf_gcd(f, F, p, K) h = gf_quo(f, g, p, K) i = 1 while h != [K.one]: G = gf_gcd(g, h, p, K) H = gf_quo(h, G, p, K) if gf_degree(H) > 0: factors.append((H, i*n)) g, h, i = gf_quo(g, G, p, K), G, i + 1 if g == [K.one]: sqf = True else: f = g if not sqf: d = gf_degree(f) // r for i in range(0, d + 1): f[i] = f[i*r] f, n = f[:d + 1], n*r else: break if all: raise ValueError("'all=True' is not supported yet") return lc, factors def gf_Qmatrix(f, p, K): """ Calculate Berlekamp's ``Q`` matrix. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_Qmatrix >>> gf_Qmatrix([3, 2, 4], 5, ZZ) [[1, 0], [3, 4]] >>> gf_Qmatrix([1, 0, 0, 0, 1], 5, ZZ) [[1, 0, 0, 0], [0, 4, 0, 0], [0, 0, 1, 0], [0, 0, 0, 4]] """ n, r = gf_degree(f), int(p) q = [K.one] + [K.zero]*(n - 1) Q = [list(q)] + [[]]*(n - 1) for i in range(1, (n - 1)*r + 1): qq, c = [(-q[-1]*f[-1]) % p], q[-1] for j in range(1, n): qq.append((q[j - 1] - c*f[-j - 1]) % p) if not (i % r): Q[i//r] = list(qq) q = qq return Q def gf_Qbasis(Q, p, K): """ Compute a basis of the kernel of ``Q``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_Qmatrix, gf_Qbasis >>> gf_Qbasis(gf_Qmatrix([1, 0, 0, 0, 1], 5, ZZ), 5, ZZ) [[1, 0, 0, 0], [0, 0, 1, 0]] >>> gf_Qbasis(gf_Qmatrix([3, 2, 4], 5, ZZ), 5, ZZ) [[1, 0]] """ Q, n = [ list(q) for q in Q ], len(Q) for k in range(0, n): Q[k][k] = (Q[k][k] - K.one) % p for k in range(0, n): for i in range(k, n): if Q[k][i]: break else: continue inv = K.invert(Q[k][i], p) for j in range(0, n): Q[j][i] = (Q[j][i]*inv) % p for j in range(0, n): t = Q[j][k] Q[j][k] = Q[j][i] Q[j][i] = t for i in range(0, n): if i != k: q = Q[k][i] for j in range(0, n): Q[j][i] = (Q[j][i] - Q[j][k]*q) % p for i in range(0, n): for j in range(0, n): if i == j: Q[i][j] = (K.one - Q[i][j]) % p else: Q[i][j] = (-Q[i][j]) % p basis = [] for q in Q: if any(q): basis.append(q) return basis def gf_berlekamp(f, p, K): """ Factor a square-free ``f`` in ``GF(p)[x]`` for small ``p``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_berlekamp >>> gf_berlekamp([1, 0, 0, 0, 1], 5, ZZ) [[1, 0, 2], [1, 0, 3]] """ Q = gf_Qmatrix(f, p, K) V = gf_Qbasis(Q, p, K) for i, v in enumerate(V): V[i] = gf_strip(list(reversed(v))) factors = [f] for k in range(1, len(V)): for f in list(factors): s = K.zero while s < p: g = gf_sub_ground(V[k], s, p, K) h = gf_gcd(f, g, p, K) if h != [K.one] and h != f: factors.remove(f) f = gf_quo(f, h, p, K) factors.extend([f, h]) if len(factors) == len(V): return _sort_factors(factors, multiple=False) s += K.one return _sort_factors(factors, multiple=False) def gf_ddf_zassenhaus(f, p, K): """ Cantor-Zassenhaus: Deterministic Distinct Degree Factorization Given a monic square-free polynomial ``f`` in ``GF(p)[x]``, computes partial distinct degree factorization ``f_1 ... f_d`` of ``f`` where ``deg(f_i) != deg(f_j)`` for ``i != j``. The result is returned as a list of pairs ``(f_i, e_i)`` where ``deg(f_i) > 0`` and ``e_i > 0`` is an argument to the equal degree factorization routine. Consider the polynomial ``x**15 - 1`` in ``GF(11)[x]``:: >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_from_dict >>> f = gf_from_dict({15: ZZ(1), 0: ZZ(-1)}, 11, ZZ) Distinct degree factorization gives:: >>> from sympy.polys.galoistools import gf_ddf_zassenhaus >>> gf_ddf_zassenhaus(f, 11, ZZ) [([1, 0, 0, 0, 0, 10], 1), ([1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1], 2)] which means ``x**15 - 1 = (x**5 - 1) (x**10 + x**5 + 1)``. To obtain factorization into irreducibles, use equal degree factorization procedure (EDF) with each of the factors. References ========== .. [1] [Gathen99]_ .. [2] [Geddes92]_ """ i, g, factors = 1, [K.one, K.zero], [] b = gf_frobenius_monomial_base(f, p, K) while 2*i <= gf_degree(f): g = gf_frobenius_map(g, f, b, p, K) h = gf_gcd(f, gf_sub(g, [K.one, K.zero], p, K), p, K) if h != [K.one]: factors.append((h, i)) f = gf_quo(f, h, p, K) g = gf_rem(g, f, p, K) b = gf_frobenius_monomial_base(f, p, K) i += 1 if f != [K.one]: return factors + [(f, gf_degree(f))] else: return factors def gf_edf_zassenhaus(f, n, p, K): """ Cantor-Zassenhaus: Probabilistic Equal Degree Factorization Given a monic square-free polynomial ``f`` in ``GF(p)[x]`` and an integer ``n``, such that ``n`` divides ``deg(f)``, returns all irreducible factors ``f_1,...,f_d`` of ``f``, each of degree ``n``. EDF procedure gives complete factorization over Galois fields. Consider the square-free polynomial ``f = x**3 + x**2 + x + 1`` in ``GF(5)[x]``. Let's compute its irreducible factors of degree one:: >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_edf_zassenhaus >>> gf_edf_zassenhaus([1,1,1,1], 1, 5, ZZ) [[1, 1], [1, 2], [1, 3]] References ========== .. [1] [Gathen99]_ .. [2] [Geddes92]_ """ factors = [f] if gf_degree(f) <= n: return factors N = gf_degree(f) // n if p != 2: b = gf_frobenius_monomial_base(f, p, K) while len(factors) < N: r = gf_random(2*n - 1, p, K) if p == 2: h = r for i in range(0, 2**(n*N - 1)): r = gf_pow_mod(r, 2, f, p, K) h = gf_add(h, r, p, K) g = gf_gcd(f, h, p, K) else: h = _gf_pow_pnm1d2(r, n, f, b, p, K) g = gf_gcd(f, gf_sub_ground(h, K.one, p, K), p, K) if g != [K.one] and g != f: factors = gf_edf_zassenhaus(g, n, p, K) \ + gf_edf_zassenhaus(gf_quo(f, g, p, K), n, p, K) return _sort_factors(factors, multiple=False) def gf_ddf_shoup(f, p, K): """ Kaltofen-Shoup: Deterministic Distinct Degree Factorization Given a monic square-free polynomial ``f`` in ``GF(p)[x]``, computes partial distinct degree factorization ``f_1,...,f_d`` of ``f`` where ``deg(f_i) != deg(f_j)`` for ``i != j``. The result is returned as a list of pairs ``(f_i, e_i)`` where ``deg(f_i) > 0`` and ``e_i > 0`` is an argument to the equal degree factorization routine. This algorithm is an improved version of Zassenhaus algorithm for large ``deg(f)`` and modulus ``p`` (especially for ``deg(f) ~ lg(p)``). Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_ddf_shoup, gf_from_dict >>> f = gf_from_dict({6: ZZ(1), 5: ZZ(-1), 4: ZZ(1), 3: ZZ(1), 1: ZZ(-1)}, 3, ZZ) >>> gf_ddf_shoup(f, 3, ZZ) [([1, 1, 0], 1), ([1, 1, 0, 1, 2], 2)] References ========== .. [1] [Kaltofen98]_ .. [2] [Shoup95]_ .. [3] [Gathen92]_ """ n = gf_degree(f) k = int(_ceil(_sqrt(n//2))) b = gf_frobenius_monomial_base(f, p, K) h = gf_frobenius_map([K.one, K.zero], f, b, p, K) # U[i] = x**(p**i) U = [[K.one, K.zero], h] + [K.zero]*(k - 1) for i in range(2, k + 1): U[i] = gf_frobenius_map(U[i-1], f, b, p, K) h, U = U[k], U[:k] # V[i] = x**(p**(k*(i+1))) V = [h] + [K.zero]*(k - 1) for i in range(1, k): V[i] = gf_compose_mod(V[i - 1], h, f, p, K) factors = [] for i, v in enumerate(V): h, j = [K.one], k - 1 for u in U: g = gf_sub(v, u, p, K) h = gf_mul(h, g, p, K) h = gf_rem(h, f, p, K) g = gf_gcd(f, h, p, K) f = gf_quo(f, g, p, K) for u in reversed(U): h = gf_sub(v, u, p, K) F = gf_gcd(g, h, p, K) if F != [K.one]: factors.append((F, k*(i + 1) - j)) g, j = gf_quo(g, F, p, K), j - 1 if f != [K.one]: factors.append((f, gf_degree(f))) return factors def gf_edf_shoup(f, n, p, K): """ Gathen-Shoup: Probabilistic Equal Degree Factorization Given a monic square-free polynomial ``f`` in ``GF(p)[x]`` and integer ``n`` such that ``n`` divides ``deg(f)``, returns all irreducible factors ``f_1,...,f_d`` of ``f``, each of degree ``n``. This is a complete factorization over Galois fields. This algorithm is an improved version of Zassenhaus algorithm for large ``deg(f)`` and modulus ``p`` (especially for ``deg(f) ~ lg(p)``). Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_edf_shoup >>> gf_edf_shoup(ZZ.map([1, 2837, 2277]), 1, 2917, ZZ) [[1, 852], [1, 1985]] References ========== .. [1] [Shoup91]_ .. [2] [Gathen92]_ """ N, q = gf_degree(f), int(p) if not N: return [] if N <= n: return [f] factors, x = [f], [K.one, K.zero] r = gf_random(N - 1, p, K) if p == 2: h = gf_pow_mod(x, q, f, p, K) H = gf_trace_map(r, h, x, n - 1, f, p, K)[1] h1 = gf_gcd(f, H, p, K) h2 = gf_quo(f, h1, p, K) factors = gf_edf_shoup(h1, n, p, K) \ + gf_edf_shoup(h2, n, p, K) else: b = gf_frobenius_monomial_base(f, p, K) H = _gf_trace_map(r, n, f, b, p, K) h = gf_pow_mod(H, (q - 1)//2, f, p, K) h1 = gf_gcd(f, h, p, K) h2 = gf_gcd(f, gf_sub_ground(h, K.one, p, K), p, K) h3 = gf_quo(f, gf_mul(h1, h2, p, K), p, K) factors = gf_edf_shoup(h1, n, p, K) \ + gf_edf_shoup(h2, n, p, K) \ + gf_edf_shoup(h3, n, p, K) return _sort_factors(factors, multiple=False) def gf_zassenhaus(f, p, K): """ Factor a square-free ``f`` in ``GF(p)[x]`` for medium ``p``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_zassenhaus >>> gf_zassenhaus(ZZ.map([1, 4, 3]), 5, ZZ) [[1, 1], [1, 3]] """ factors = [] for factor, n in gf_ddf_zassenhaus(f, p, K): factors += gf_edf_zassenhaus(factor, n, p, K) return _sort_factors(factors, multiple=False) def gf_shoup(f, p, K): """ Factor a square-free ``f`` in ``GF(p)[x]`` for large ``p``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_shoup >>> gf_shoup(ZZ.map([1, 4, 3]), 5, ZZ) [[1, 1], [1, 3]] """ factors = [] for factor, n in gf_ddf_shoup(f, p, K): factors += gf_edf_shoup(factor, n, p, K) return _sort_factors(factors, multiple=False) _factor_methods = { 'berlekamp': gf_berlekamp, # ``p`` : small 'zassenhaus': gf_zassenhaus, # ``p`` : medium 'shoup': gf_shoup, # ``p`` : large } def gf_factor_sqf(f, p, K, method=None): """ Factor a square-free polynomial ``f`` in ``GF(p)[x]``. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_factor_sqf >>> gf_factor_sqf(ZZ.map([3, 2, 4]), 5, ZZ) (3, [[1, 1], [1, 3]]) """ lc, f = gf_monic(f, p, K) if gf_degree(f) < 1: return lc, [] method = method or query('GF_FACTOR_METHOD') if method is not None: factors = _factor_methods[method](f, p, K) else: factors = gf_zassenhaus(f, p, K) return lc, factors def gf_factor(f, p, K): """ Factor (non square-free) polynomials in ``GF(p)[x]``. Given a possibly non square-free polynomial ``f`` in ``GF(p)[x]``, returns its complete factorization into irreducibles:: f_1(x)**e_1 f_2(x)**e_2 ... f_d(x)**e_d where each ``f_i`` is a monic polynomial and ``gcd(f_i, f_j) == 1``, for ``i != j``. The result is given as a tuple consisting of the leading coefficient of ``f`` and a list of factors of ``f`` with their multiplicities. The algorithm proceeds by first computing square-free decomposition of ``f`` and then iteratively factoring each of square-free factors. Consider a non square-free polynomial ``f = (7*x + 1) (x + 2)**2`` in ``GF(11)[x]``. We obtain its factorization into irreducibles as follows:: >>> from sympy.polys.domains import ZZ >>> from sympy.polys.galoistools import gf_factor >>> gf_factor(ZZ.map([5, 2, 7, 2]), 11, ZZ) (5, [([1, 2], 1), ([1, 8], 2)]) We arrived with factorization ``f = 5 (x + 2) (x + 8)**2``. We didn't recover the exact form of the input polynomial because we requested to get monic factors of ``f`` and its leading coefficient separately. Square-free factors of ``f`` can be factored into irreducibles over ``GF(p)`` using three very different methods: Berlekamp efficient for very small values of ``p`` (usually ``p < 25``) Cantor-Zassenhaus efficient on average input and with "typical" ``p`` Shoup-Kaltofen-Gathen efficient with very large inputs and modulus If you want to use a specific factorization method, instead of the default one, set ``GF_FACTOR_METHOD`` with one of ``berlekamp``, ``zassenhaus`` or ``shoup`` values. References ========== .. [1] [Gathen99]_ """ lc, f = gf_monic(f, p, K) if gf_degree(f) < 1: return lc, [] factors = [] for g, n in gf_sqf_list(f, p, K)[1]: for h in gf_factor_sqf(g, p, K)[1]: factors.append((h, n)) return lc, _sort_factors(factors) def gf_value(f, a): """ Value of polynomial 'f' at 'a' in field R. Examples ======== >>> from sympy.polys.galoistools import gf_value >>> gf_value([1, 7, 2, 4], 11) 2204 """ result = 0 for c in f: result *= a result += c return result def linear_congruence(a, b, m): """ Returns the values of x satisfying a*x congruent b mod(m) Here m is positive integer and a, b are natural numbers. This function returns only those values of x which are distinct mod(m). Examples ======== >>> from sympy.polys.galoistools import linear_congruence >>> linear_congruence(3, 12, 15) [4, 9, 14] There are 3 solutions distinct mod(15) since gcd(a, m) = gcd(3, 15) = 3. References ========== .. [1] https://en.wikipedia.org/wiki/Linear_congruence_theorem """ from sympy.polys.polytools import gcdex if a % m == 0: if b % m == 0: return list(range(m)) else: return [] r, _, g = gcdex(a, m) if b % g != 0: return [] return [(r * b // g + t * m // g) % m for t in range(g)] def _raise_mod_power(x, s, p, f): """ Used in gf_csolve to generate solutions of f(x) cong 0 mod(p**(s + 1)) from the solutions of f(x) cong 0 mod(p**s). Examples ======== >>> from sympy.polys.galoistools import _raise_mod_power >>> from sympy.polys.galoistools import csolve_prime These is the solutions of f(x) = x**2 + x + 7 cong 0 mod(3) >>> f = [1, 1, 7] >>> csolve_prime(f, 3) [1] >>> [ i for i in range(3) if not (i**2 + i + 7) % 3] [1] The solutions of f(x) cong 0 mod(9) are constructed from the values returned from _raise_mod_power: >>> x, s, p = 1, 1, 3 >>> V = _raise_mod_power(x, s, p, f) >>> [x + v * p**s for v in V] [1, 4, 7] And these are confirmed with the following: >>> [ i for i in range(3**2) if not (i**2 + i + 7) % 3**2] [1, 4, 7] """ from sympy.polys.domains import ZZ f_f = gf_diff(f, p, ZZ) alpha = gf_value(f_f, x) beta = - gf_value(f, x) // p**s return linear_congruence(alpha, beta, p) def csolve_prime(f, p, e=1): """ Solutions of f(x) congruent 0 mod(p**e). Examples ======== >>> from sympy.polys.galoistools import csolve_prime >>> csolve_prime([1, 1, 7], 3, 1) [1] >>> csolve_prime([1, 1, 7], 3, 2) [1, 4, 7] Solutions [7, 4, 1] (mod 3**2) are generated by ``_raise_mod_power()`` from solution [1] (mod 3). """ from sympy.polys.domains import ZZ X1 = [i for i in range(p) if gf_eval(f, i, p, ZZ) == 0] if e == 1: return X1 X = [] S = list(zip(X1, [1]*len(X1))) while S: x, s = S.pop() if s == e: X.append(x) else: s1 = s + 1 ps = p**s S.extend([(x + v*ps, s1) for v in _raise_mod_power(x, s, p, f)]) return sorted(X) def gf_csolve(f, n): """ To solve f(x) congruent 0 mod(n). n is divided into canonical factors and f(x) cong 0 mod(p**e) will be solved for each factor. Applying the Chinese Remainder Theorem to the results returns the final answers. Examples ======== Solve [1, 1, 7] congruent 0 mod(189): >>> from sympy.polys.galoistools import gf_csolve >>> gf_csolve([1, 1, 7], 189) [13, 49, 76, 112, 139, 175] References ========== .. [1] 'An introduction to the Theory of Numbers' 5th Edition by Ivan Niven, Zuckerman and Montgomery. """ from sympy.polys.domains import ZZ P = factorint(n) X = [csolve_prime(f, p, e) for p, e in P.items()] pools = list(map(tuple, X)) perms = [[]] for pool in pools: perms = [x + [y] for x in perms for y in pool] dist_factors = [pow(p, e) for p, e in P.items()] return sorted([gf_crt(per, dist_factors, ZZ) for per in perms])

8f2f64c1f1820f06619c366df5c55d93e54c8ec94587d20f521c7c217f85871a

# -*- coding: utf-8 -*- """ This module contains functions for the computation of Euclidean, (generalized) Sturmian, (modified) subresultant polynomial remainder sequences (prs's) of two polynomials; included are also three functions for the computation of the resultant of two polynomials. Except for the function res_z(), which computes the resultant of two polynomials, the pseudo-remainder function prem() of sympy is _not_ used by any of the functions in the module. Instead of prem() we use the function rem_z(). Included is also the function quo_z(). An explanation of why we avoid prem() can be found in the references stated in the docstring of rem_z(). 1. Theoretical background: ========================== Consider the polynomials f, g ∈ Z[x] of degrees deg(f) = n and deg(g) = m with n ≥ m. Definition 1: ============= The sign sequence of a polynomial remainder sequence (prs) is the sequence of signs of the leading coefficients of its polynomials. Sign sequences can be computed with the function: sign_seq(poly_seq, x) Definition 2: ============= A polynomial remainder sequence (prs) is called complete if the degree difference between any two consecutive polynomials is 1; otherwise, it called incomplete. It is understood that f, g belong to the sequences mentioned in the two definitions above. 1A. Euclidean and subresultant prs's: ===================================== The subresultant prs of f, g is a sequence of polynomials in Z[x] analogous to the Euclidean prs, the sequence obtained by applying on f, g Euclid’s algorithm for polynomial greatest common divisors (gcd) in Q[x]. The subresultant prs differs from the Euclidean prs in that the coefficients of each polynomial in the former sequence are determinants --- also referred to as subresultants --- of appropriately selected sub-matrices of sylvester1(f, g, x), Sylvester’s matrix of 1840 of dimensions (n + m) × (n + m). Recall that the determinant of sylvester1(f, g, x) itself is called the resultant of f, g and serves as a criterion of whether the two polynomials have common roots or not. In sympy the resultant is computed with the function resultant(f, g, x). This function does _not_ evaluate the determinant of sylvester(f, g, x, 1); instead, it returns the last member of the subresultant prs of f, g, multiplied (if needed) by an appropriate power of -1; see the caveat below. In this module we use three functions to compute the resultant of f, g: a) res(f, g, x) computes the resultant by evaluating the determinant of sylvester(f, g, x, 1); b) res_q(f, g, x) computes the resultant recursively, by performing polynomial divisions in Q[x] with the function rem(); c) res_z(f, g, x) computes the resultant recursively, by performing polynomial divisions in Z[x] with the function prem(). Caveat: If Df = degree(f, x) and Dg = degree(g, x), then: resultant(f, g, x) = (-1)**(Df*Dg) * resultant(g, f, x). For complete prs’s the sign sequence of the Euclidean prs of f, g is identical to the sign sequence of the subresultant prs of f, g and the coefficients of one sequence are easily computed from the coefficients of the other. For incomplete prs’s the polynomials in the subresultant prs, generally differ in sign from those of the Euclidean prs, and --- unlike the case of complete prs’s --- it is not at all obvious how to compute the coefficients of one sequence from the coefficients of the other. 1B. Sturmian and modified subresultant prs's: ============================================= For the same polynomials f, g ∈ Z[x] mentioned above, their ``modified'' subresultant prs is a sequence of polynomials similar to the Sturmian prs, the sequence obtained by applying in Q[x] Sturm’s algorithm on f, g. The two sequences differ in that the coefficients of each polynomial in the modified subresultant prs are the determinants --- also referred to as modified subresultants --- of appropriately selected sub-matrices of sylvester2(f, g, x), Sylvester’s matrix of 1853 of dimensions 2n × 2n. The determinant of sylvester2 itself is called the modified resultant of f, g and it also can serve as a criterion of whether the two polynomials have common roots or not. For complete prs’s the sign sequence of the Sturmian prs of f, g is identical to the sign sequence of the modified subresultant prs of f, g and the coefficients of one sequence are easily computed from the coefficients of the other. For incomplete prs’s the polynomials in the modified subresultant prs, generally differ in sign from those of the Sturmian prs, and --- unlike the case of complete prs’s --- it is not at all obvious how to compute the coefficients of one sequence from the coefficients of the other. As Sylvester pointed out, the coefficients of the polynomial remainders obtained as (modified) subresultants are the smallest possible without introducing rationals and without computing (integer) greatest common divisors. 1C. On terminology: =================== Whence the terminology? Well generalized Sturmian prs's are ``modifications'' of Euclidean prs's; the hint came from the title of the Pell-Gordon paper of 1917. In the literature one also encounters the name ``non signed'' and ``signed'' prs for Euclidean and Sturmian prs respectively. Likewise ``non signed'' and ``signed'' subresultant prs for subresultant and modified subresultant prs respectively. 2. Functions in the module: =========================== No function utilizes sympy's function prem(). 2A. Matrices: ============= The functions sylvester(f, g, x, method=1) and sylvester(f, g, x, method=2) compute either Sylvester matrix. They can be used to compute (modified) subresultant prs's by direct determinant evaluation. The function bezout(f, g, x, method='prs') provides a matrix of smaller dimensions than either Sylvester matrix. It is the function of choice for computing (modified) subresultant prs's by direct determinant evaluation. sylvester(f, g, x, method=1) sylvester(f, g, x, method=2) bezout(f, g, x, method='prs') The following identity holds: bezout(f, g, x, method='prs') = backward_eye(deg(f))*bezout(f, g, x, method='bz')*backward_eye(deg(f)) 2B. Subresultant and modified subresultant prs's by =================================================== determinant evaluations: ======================= We use the Sylvester matrices of 1840 and 1853 to compute, respectively, subresultant and modified subresultant polynomial remainder sequences. However, for large matrices this approach takes a lot of time. Instead of utilizing the Sylvester matrices, we can employ the Bezout matrix which is of smaller dimensions. subresultants_sylv(f, g, x) modified_subresultants_sylv(f, g, x) subresultants_bezout(f, g, x) modified_subresultants_bezout(f, g, x) 2C. Subresultant prs's by ONE determinant evaluation: ===================================================== All three functions in this section evaluate one determinant per remainder polynomial; this is the determinant of an appropriately selected sub-matrix of sylvester1(f, g, x), Sylvester’s matrix of 1840. To compute the remainder polynomials the function subresultants_rem(f, g, x) employs rem(f, g, x). By contrast, the other two functions implement Van Vleck’s ideas of 1900 and compute the remainder polynomials by trinagularizing sylvester2(f, g, x), Sylvester’s matrix of 1853. subresultants_rem(f, g, x) subresultants_vv(f, g, x) subresultants_vv_2(f, g, x). 2E. Euclidean, Sturmian prs's in Q[x]: ====================================== euclid_q(f, g, x) sturm_q(f, g, x) 2F. Euclidean, Sturmian and (modified) subresultant prs's P-G: ============================================================== All functions in this section are based on the Pell-Gordon (P-G) theorem of 1917. Computations are done in Q[x], employing the function rem(f, g, x) for the computation of the remainder polynomials. euclid_pg(f, g, x) sturm pg(f, g, x) subresultants_pg(f, g, x) modified_subresultants_pg(f, g, x) 2G. Euclidean, Sturmian and (modified) subresultant prs's A-M-V: ================================================================ All functions in this section are based on the Akritas-Malaschonok- Vigklas (A-M-V) theorem of 2015. Computations are done in Z[x], employing the function rem_z(f, g, x) for the computation of the remainder polynomials. euclid_amv(f, g, x) sturm_amv(f, g, x) subresultants_amv(f, g, x) modified_subresultants_amv(f, g, x) 2Ga. Exception: =============== subresultants_amv_q(f, g, x) This function employs rem(f, g, x) for the computation of the remainder polynomials, despite the fact that it implements the A-M-V Theorem. It is included in our module in order to show that theorems P-G and A-M-V can be implemented utilizing either the function rem(f, g, x) or the function rem_z(f, g, x). For clearly historical reasons --- since the Collins-Brown-Traub coefficients-reduction factor β_i was not available in 1917 --- we have implemented the Pell-Gordon theorem with the function rem(f, g, x) and the A-M-V Theorem with the function rem_z(f, g, x). 2H. Resultants: =============== res(f, g, x) res_q(f, g, x) res_z(f, g, x) """ from __future__ import print_function, division from sympy import (Abs, degree, expand, eye, floor, LC, Matrix, nan, Poly, pprint) from sympy import (QQ, pquo, quo, prem, rem, S, sign, simplify, summation, var, zeros) from sympy.polys.polyerrors import PolynomialError def sylvester(f, g, x, method = 1): ''' The input polynomials f, g are in Z[x] or in Q[x]. Let m = degree(f, x), n = degree(g, x) and mx = max( m , n ). a. If method = 1 (default), computes sylvester1, Sylvester's matrix of 1840 of dimension (m + n) x (m + n). The determinants of properly chosen submatrices of this matrix (a.k.a. subresultants) can be used to compute the coefficients of the Euclidean PRS of f, g. b. If method = 2, computes sylvester2, Sylvester's matrix of 1853 of dimension (2*mx) x (2*mx). The determinants of properly chosen submatrices of this matrix (a.k.a. ``modified'' subresultants) can be used to compute the coefficients of the Sturmian PRS of f, g. Applications of these Matrices can be found in the references below. Especially, for applications of sylvester2, see the first reference!! References ========== 1. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``On a Theorem by Van Vleck Regarding Sturm Sequences. Serdica Journal of Computing, Vol. 7, No 4, 101–134, 2013. 2. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``Sturm Sequences and Modified Subresultant Polynomial Remainder Sequences.'' Serdica Journal of Computing, Vol. 8, No 1, 29–46, 2014. ''' # obtain degrees of polys m, n = degree( Poly(f, x), x), degree( Poly(g, x), x) # Special cases: # A:: case m = n < 0 (i.e. both polys are 0) if m == n and n < 0: return Matrix([]) # B:: case m = n = 0 (i.e. both polys are constants) if m == n and n == 0: return Matrix([]) # C:: m == 0 and n < 0 or m < 0 and n == 0 # (i.e. one poly is constant and the other is 0) if m == 0 and n < 0: return Matrix([]) elif m < 0 and n == 0: return Matrix([]) # D:: m >= 1 and n < 0 or m < 0 and n >=1 # (i.e. one poly is of degree >=1 and the other is 0) if m >= 1 and n < 0: return Matrix([0]) elif m < 0 and n >= 1: return Matrix([0]) fp = Poly(f, x).all_coeffs() gp = Poly(g, x).all_coeffs() # Sylvester's matrix of 1840 (default; a.k.a. sylvester1) if method <= 1: M = zeros(m + n) k = 0 for i in range(n): j = k for coeff in fp: M[i, j] = coeff j = j + 1 k = k + 1 k = 0 for i in range(n, m + n): j = k for coeff in gp: M[i, j] = coeff j = j + 1 k = k + 1 return M # Sylvester's matrix of 1853 (a.k.a sylvester2) if method >= 2: if len(fp) < len(gp): h = [] for i in range(len(gp) - len(fp)): h.append(0) fp[ : 0] = h else: h = [] for i in range(len(fp) - len(gp)): h.append(0) gp[ : 0] = h mx = max(m, n) dim = 2*mx M = zeros( dim ) k = 0 for i in range( mx ): j = k for coeff in fp: M[2*i, j] = coeff j = j + 1 j = k for coeff in gp: M[2*i + 1, j] = coeff j = j + 1 k = k + 1 return M def process_matrix_output(poly_seq, x): """ poly_seq is a polynomial remainder sequence computed either by (modified_)subresultants_bezout or by (modified_)subresultants_sylv. This function removes from poly_seq all zero polynomials as well as all those whose degree is equal to the degree of a preceding polynomial in poly_seq, as we scan it from left to right. """ L = poly_seq[:] # get a copy of the input sequence d = degree(L[1], x) i = 2 while i < len(L): d_i = degree(L[i], x) if d_i < 0: # zero poly L.remove(L[i]) i = i - 1 if d == d_i: # poly degree equals degree of previous poly L.remove(L[i]) i = i - 1 if d_i >= 0: d = d_i i = i + 1 return L def subresultants_sylv(f, g, x): """ The input polynomials f, g are in Z[x] or in Q[x]. It is assumed that deg(f) >= deg(g). Computes the subresultant polynomial remainder sequence (prs) of f, g by evaluating determinants of appropriately selected submatrices of sylvester(f, g, x, 1). The dimensions of the latter are (deg(f) + deg(g)) x (deg(f) + deg(g)). Each coefficient is computed by evaluating the determinant of the corresponding submatrix of sylvester(f, g, x, 1). If the subresultant prs is complete, then the output coincides with the Euclidean sequence of the polynomials f, g. References: =========== 1. G.M.Diaz-Toca,L.Gonzalez-Vega: Various New Expressions for Subresultants and Their Applications. Appl. Algebra in Engin., Communic. and Comp., Vol. 15, 233–266, 2004. """ # make sure neither f nor g is 0 if f == 0 or g == 0: return [f, g] n = degF = degree(f, x) m = degG = degree(g, x) # make sure proper degrees if n == 0 and m == 0: return [f, g] if n < m: n, m, degF, degG, f, g = m, n, degG, degF, g, f if n > 0 and m == 0: return [f, g] SR_L = [f, g] # subresultant list # form matrix sylvester(f, g, x, 1) S = sylvester(f, g, x, 1) # pick appropriate submatrices of S # and form subresultant polys j = m - 1 while j > 0: Sp = S[:, :] # copy of S # delete last j rows of coeffs of g for ind in range(m + n - j, m + n): Sp.row_del(m + n - j) # delete last j rows of coeffs of f for ind in range(m - j, m): Sp.row_del(m - j) # evaluate determinants and form coefficients list coeff_L, k, l = [], Sp.rows, 0 while l <= j: coeff_L.append(Sp[ : , 0 : k].det()) Sp.col_swap(k - 1, k + l) l += 1 # form poly and append to SP_L SR_L.append(Poly(coeff_L, x).as_expr()) j -= 1 # j = 0 SR_L.append(S.det()) return process_matrix_output(SR_L, x) def modified_subresultants_sylv(f, g, x): """ The input polynomials f, g are in Z[x] or in Q[x]. It is assumed that deg(f) >= deg(g). Computes the modified subresultant polynomial remainder sequence (prs) of f, g by evaluating determinants of appropriately selected submatrices of sylvester(f, g, x, 2). The dimensions of the latter are (2*deg(f)) x (2*deg(f)). Each coefficient is computed by evaluating the determinant of the corresponding submatrix of sylvester(f, g, x, 2). If the modified subresultant prs is complete, then the output coincides with the Sturmian sequence of the polynomials f, g. References: =========== 1. A. G. Akritas,G.I. Malaschonok and P.S. Vigklas: Sturm Sequences and Modified Subresultant Polynomial Remainder Sequences. Serdica Journal of Computing, Vol. 8, No 1, 29--46, 2014. """ # make sure neither f nor g is 0 if f == 0 or g == 0: return [f, g] n = degF = degree(f, x) m = degG = degree(g, x) # make sure proper degrees if n == 0 and m == 0: return [f, g] if n < m: n, m, degF, degG, f, g = m, n, degG, degF, g, f if n > 0 and m == 0: return [f, g] SR_L = [f, g] # modified subresultant list # form matrix sylvester(f, g, x, 2) S = sylvester(f, g, x, 2) # pick appropriate submatrices of S # and form modified subresultant polys j = m - 1 while j > 0: # delete last 2*j rows of pairs of coeffs of f, g Sp = S[0:2*n - 2*j, :] # copy of first 2*n - 2*j rows of S # evaluate determinants and form coefficients list coeff_L, k, l = [], Sp.rows, 0 while l <= j: coeff_L.append(Sp[ : , 0 : k].det()) Sp.col_swap(k - 1, k + l) l += 1 # form poly and append to SP_L SR_L.append(Poly(coeff_L, x).as_expr()) j -= 1 # j = 0 SR_L.append(S.det()) return process_matrix_output(SR_L, x) def res(f, g, x): """ The input polynomials f, g are in Z[x] or in Q[x]. The output is the resultant of f, g computed by evaluating the determinant of the matrix sylvester(f, g, x, 1). References: =========== 1. J. S. Cohen: Computer Algebra and Symbolic Computation - Mathematical Methods. A. K. Peters, 2003. """ if f == 0 or g == 0: raise PolynomialError("The resultant of %s and %s is not defined" % (f, g)) else: return sylvester(f, g, x, 1).det() def res_q(f, g, x): """ The input polynomials f, g are in Z[x] or in Q[x]. The output is the resultant of f, g computed recursively by polynomial divisions in Q[x], using the function rem. See Cohen's book p. 281. References: =========== 1. J. S. Cohen: Computer Algebra and Symbolic Computation - Mathematical Methods. A. K. Peters, 2003. """ m = degree(f, x) n = degree(g, x) if m < n: return (-1)**(m*n) * res_q(g, f, x) elif n == 0: # g is a constant return g**m else: r = rem(f, g, x) if r == 0: return 0 else: s = degree(r, x) l = LC(g, x) return (-1)**(m*n) * l**(m-s)*res_q(g, r, x) def res_z(f, g, x): """ The input polynomials f, g are in Z[x] or in Q[x]. The output is the resultant of f, g computed recursively by polynomial divisions in Z[x], using the function prem(). See Cohen's book p. 283. References: =========== 1. J. S. Cohen: Computer Algebra and Symbolic Computation - Mathematical Methods. A. K. Peters, 2003. """ m = degree(f, x) n = degree(g, x) if m < n: return (-1)**(m*n) * res_z(g, f, x) elif n == 0: # g is a constant return g**m else: r = prem(f, g, x) if r == 0: return 0 else: delta = m - n + 1 w = (-1)**(m*n) * res_z(g, r, x) s = degree(r, x) l = LC(g, x) k = delta * n - m + s return quo(w, l**k, x) def sign_seq(poly_seq, x): """ Given a sequence of polynomials poly_seq, it returns the sequence of signs of the leading coefficients of the polynomials in poly_seq. """ return [sign(LC(poly_seq[i], x)) for i in range(len(poly_seq))] def bezout(p, q, x, method='bz'): """ The input polynomials p, q are in Z[x] or in Q[x]. Let mx = max( degree(p, x) , degree(q, x) ). The default option bezout(p, q, x, method='bz') returns Bezout's symmetric matrix of p and q, of dimensions (mx) x (mx). The determinant of this matrix is equal to the determinant of sylvester2, Sylvester's matrix of 1853, whose dimensions are (2*mx) x (2*mx); however the subresultants of these two matrices may differ. The other option, bezout(p, q, x, 'prs'), is of interest to us in this module because it returns a matrix equivalent to sylvester2. In this case all subresultants of the two matrices are identical. Both the subresultant polynomial remainder sequence (prs) and the modified subresultant prs of p and q can be computed by evaluating determinants of appropriately selected submatrices of bezout(p, q, x, 'prs') --- one determinant per coefficient of the remainder polynomials. The matrices bezout(p, q, x, 'bz') and bezout(p, q, x, 'prs') are related by the formula bezout(p, q, x, 'prs') = backward_eye(deg(p)) * bezout(p, q, x, 'bz') * backward_eye(deg(p)), where backward_eye() is the backward identity function. References ========== 1. G.M.Diaz-Toca,L.Gonzalez-Vega: Various New Expressions for Subresultants and Their Applications. Appl. Algebra in Engin., Communic. and Comp., Vol. 15, 233–266, 2004. """ # obtain degrees of polys m, n = degree( Poly(p, x), x), degree( Poly(q, x), x) # Special cases: # A:: case m = n < 0 (i.e. both polys are 0) if m == n and n < 0: return Matrix([]) # B:: case m = n = 0 (i.e. both polys are constants) if m == n and n == 0: return Matrix([]) # C:: m == 0 and n < 0 or m < 0 and n == 0 # (i.e. one poly is constant and the other is 0) if m == 0 and n < 0: return Matrix([]) elif m < 0 and n == 0: return Matrix([]) # D:: m >= 1 and n < 0 or m < 0 and n >=1 # (i.e. one poly is of degree >=1 and the other is 0) if m >= 1 and n < 0: return Matrix([0]) elif m < 0 and n >= 1: return Matrix([0]) y = var('y') # expr is 0 when x = y expr = p * q.subs({x:y}) - p.subs({x:y}) * q # hence expr is exactly divisible by x - y poly = Poly( quo(expr, x-y), x, y) # form Bezout matrix and store them in B as indicated to get # the LC coefficient of each poly either in the first position # of each row (method='prs') or in the last (method='bz'). mx = max(m, n) B = zeros(mx) for i in range(mx): for j in range(mx): if method == 'prs': B[mx - 1 - i, mx - 1 - j] = poly.nth(i, j) else: B[i, j] = poly.nth(i, j) return B def backward_eye(n): ''' Returns the backward identity matrix of dimensions n x n. Needed to "turn" the Bezout matrices so that the leading coefficients are first. See docstring of the function bezout(p, q, x, method='bz'). ''' M = eye(n) # identity matrix of order n for i in range(int(M.rows / 2)): M.row_swap(0 + i, M.rows - 1 - i) return M def subresultants_bezout(p, q, x): """ The input polynomials p, q are in Z[x] or in Q[x]. It is assumed that degree(p, x) >= degree(q, x). Computes the subresultant polynomial remainder sequence of p, q by evaluating determinants of appropriately selected submatrices of bezout(p, q, x, 'prs'). The dimensions of the latter are deg(p) x deg(p). Each coefficient is computed by evaluating the determinant of the corresponding submatrix of bezout(p, q, x, 'prs'). bezout(p, q, x, 'prs) is used instead of sylvester(p, q, x, 1), Sylvester's matrix of 1840, because the dimensions of the latter are (deg(p) + deg(q)) x (deg(p) + deg(q)). If the subresultant prs is complete, then the output coincides with the Euclidean sequence of the polynomials p, q. References ========== 1. G.M.Diaz-Toca,L.Gonzalez-Vega: Various New Expressions for Subresultants and Their Applications. Appl. Algebra in Engin., Communic. and Comp., Vol. 15, 233–266, 2004. """ # make sure neither p nor q is 0 if p == 0 or q == 0: return [p, q] f, g = p, q n = degF = degree(f, x) m = degG = degree(g, x) # make sure proper degrees if n == 0 and m == 0: return [f, g] if n < m: n, m, degF, degG, f, g = m, n, degG, degF, g, f if n > 0 and m == 0: return [f, g] SR_L = [f, g] # subresultant list F = LC(f, x)**(degF - degG) # form the bezout matrix B = bezout(f, g, x, 'prs') # pick appropriate submatrices of B # and form subresultant polys if degF > degG: j = 2 if degF == degG: j = 1 while j <= degF: M = B[0:j, :] k, coeff_L = j - 1, [] while k <= degF - 1: coeff_L.append(M[: ,0 : j].det()) if k < degF - 1: M.col_swap(j - 1, k + 1) k = k + 1 # apply Theorem 2.1 in the paper by Toca & Vega 2004 # to get correct signs SR_L.append((int((-1)**(j*(j-1)/2)) * Poly(coeff_L, x) / F).as_expr()) j = j + 1 return process_matrix_output(SR_L, x) def modified_subresultants_bezout(p, q, x): """ The input polynomials p, q are in Z[x] or in Q[x]. It is assumed that degree(p, x) >= degree(q, x). Computes the modified subresultant polynomial remainder sequence of p, q by evaluating determinants of appropriately selected submatrices of bezout(p, q, x, 'prs'). The dimensions of the latter are deg(p) x deg(p). Each coefficient is computed by evaluating the determinant of the corresponding submatrix of bezout(p, q, x, 'prs'). bezout(p, q, x, 'prs') is used instead of sylvester(p, q, x, 2), Sylvester's matrix of 1853, because the dimensions of the latter are 2*deg(p) x 2*deg(p). If the modified subresultant prs is complete, and LC( p ) > 0, the output coincides with the (generalized) Sturm's sequence of the polynomials p, q. References ========== 1. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``Sturm Sequences and Modified Subresultant Polynomial Remainder Sequences.'' Serdica Journal of Computing, Vol. 8, No 1, 29–46, 2014. 2. G.M.Diaz-Toca,L.Gonzalez-Vega: Various New Expressions for Subresultants and Their Applications. Appl. Algebra in Engin., Communic. and Comp., Vol. 15, 233–266, 2004. """ # make sure neither p nor q is 0 if p == 0 or q == 0: return [p, q] f, g = p, q n = degF = degree(f, x) m = degG = degree(g, x) # make sure proper degrees if n == 0 and m == 0: return [f, g] if n < m: n, m, degF, degG, f, g = m, n, degG, degF, g, f if n > 0 and m == 0: return [f, g] SR_L = [f, g] # subresultant list # form the bezout matrix B = bezout(f, g, x, 'prs') # pick appropriate submatrices of B # and form subresultant polys if degF > degG: j = 2 if degF == degG: j = 1 while j <= degF: M = B[0:j, :] k, coeff_L = j - 1, [] while k <= degF - 1: coeff_L.append(M[: ,0 : j].det()) if k < degF - 1: M.col_swap(j - 1, k + 1) k = k + 1 ## Theorem 2.1 in the paper by Toca & Vega 2004 is _not needed_ ## in this case since ## the bezout matrix is equivalent to sylvester2 SR_L.append(( Poly(coeff_L, x)).as_expr()) j = j + 1 return process_matrix_output(SR_L, x) def sturm_pg(p, q, x, method=0): """ p, q are polynomials in Z[x] or Q[x]. It is assumed that degree(p, x) >= degree(q, x). Computes the (generalized) Sturm sequence of p and q in Z[x] or Q[x]. If q = diff(p, x, 1) it is the usual Sturm sequence. A. If method == 0, default, the remainder coefficients of the sequence are (in absolute value) ``modified'' subresultants, which for non-monic polynomials are greater than the coefficients of the corresponding subresultants by the factor Abs(LC(p)**( deg(p)- deg(q))). B. If method == 1, the remainder coefficients of the sequence are (in absolute value) subresultants, which for non-monic polynomials are smaller than the coefficients of the corresponding ``modified'' subresultants by the factor Abs(LC(p)**( deg(p)- deg(q))). If the Sturm sequence is complete, method=0 and LC( p ) > 0, the coefficients of the polynomials in the sequence are ``modified'' subresultants. That is, they are determinants of appropriately selected submatrices of sylvester2, Sylvester's matrix of 1853. In this case the Sturm sequence coincides with the ``modified'' subresultant prs, of the polynomials p, q. If the Sturm sequence is incomplete and method=0 then the signs of the coefficients of the polynomials in the sequence may differ from the signs of the coefficients of the corresponding polynomials in the ``modified'' subresultant prs; however, the absolute values are the same. To compute the coefficients, no determinant evaluation takes place. Instead, polynomial divisions in Q[x] are performed, using the function rem(p, q, x); the coefficients of the remainders computed this way become (``modified'') subresultants with the help of the Pell-Gordon Theorem of 1917. See also the function euclid_pg(p, q, x). References ========== 1. Pell A. J., R. L. Gordon. The Modified Remainders Obtained in Finding the Highest Common Factor of Two Polynomials. Annals of MatheMatics, Second Series, 18 (1917), No. 4, 188–193. 2. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``Sturm Sequences and Modified Subresultant Polynomial Remainder Sequences.'' Serdica Journal of Computing, Vol. 8, No 1, 29–46, 2014. """ # make sure neither p nor q is 0 if p == 0 or q == 0: return [p, q] # make sure proper degrees d0 = degree(p, x) d1 = degree(q, x) if d0 == 0 and d1 == 0: return [p, q] if d1 > d0: d0, d1 = d1, d0 p, q = q, p if d0 > 0 and d1 == 0: return [p,q] # make sure LC(p) > 0 flag = 0 if LC(p,x) < 0: flag = 1 p = -p q = -q # initialize lcf = LC(p, x)**(d0 - d1) # lcf * subr = modified subr a0, a1 = p, q # the input polys sturm_seq = [a0, a1] # the output list del0 = d0 - d1 # degree difference rho1 = LC(a1, x) # leading coeff of a1 exp_deg = d1 - 1 # expected degree of a2 a2 = - rem(a0, a1, domain=QQ) # first remainder rho2 = LC(a2,x) # leading coeff of a2 d2 = degree(a2, x) # actual degree of a2 deg_diff_new = exp_deg - d2 # expected - actual degree del1 = d1 - d2 # degree difference # mul_fac is the factor by which a2 is multiplied to # get integer coefficients mul_fac_old = rho1**(del0 + del1 - deg_diff_new) # append accordingly if method == 0: sturm_seq.append( simplify(lcf * a2 * Abs(mul_fac_old))) else: sturm_seq.append( simplify( a2 * Abs(mul_fac_old))) # main loop deg_diff_old = deg_diff_new while d2 > 0: a0, a1, d0, d1 = a1, a2, d1, d2 # update polys and degrees del0 = del1 # update degree difference exp_deg = d1 - 1 # new expected degree a2 = - rem(a0, a1, domain=QQ) # new remainder rho3 = LC(a2, x) # leading coeff of a2 d2 = degree(a2, x) # actual degree of a2 deg_diff_new = exp_deg - d2 # expected - actual degree del1 = d1 - d2 # degree difference # take into consideration the power # rho1**deg_diff_old that was "left out" expo_old = deg_diff_old # rho1 raised to this power expo_new = del0 + del1 - deg_diff_new # rho2 raised to this power # update variables and append mul_fac_new = rho2**(expo_new) * rho1**(expo_old) * mul_fac_old deg_diff_old, mul_fac_old = deg_diff_new, mul_fac_new rho1, rho2 = rho2, rho3 if method == 0: sturm_seq.append( simplify(lcf * a2 * Abs(mul_fac_old))) else: sturm_seq.append( simplify( a2 * Abs(mul_fac_old))) if flag: # change the sign of the sequence sturm_seq = [-i for i in sturm_seq] # gcd is of degree > 0 ? m = len(sturm_seq) if sturm_seq[m - 1] == nan or sturm_seq[m - 1] == 0: sturm_seq.pop(m - 1) return sturm_seq def sturm_q(p, q, x): """ p, q are polynomials in Z[x] or Q[x]. It is assumed that degree(p, x) >= degree(q, x). Computes the (generalized) Sturm sequence of p and q in Q[x]. Polynomial divisions in Q[x] are performed, using the function rem(p, q, x). The coefficients of the polynomials in the Sturm sequence can be uniquely determined from the corresponding coefficients of the polynomials found either in: (a) the ``modified'' subresultant prs, (references 1, 2) or in (b) the subresultant prs (reference 3). References ========== 1. Pell A. J., R. L. Gordon. The Modified Remainders Obtained in Finding the Highest Common Factor of Two Polynomials. Annals of MatheMatics, Second Series, 18 (1917), No. 4, 188–193. 2 Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``Sturm Sequences and Modified Subresultant Polynomial Remainder Sequences.'' Serdica Journal of Computing, Vol. 8, No 1, 29–46, 2014. 3. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``A Basic Result on the Theory of Subresultants.'' Serdica Journal of Computing 10 (2016), Νο.1, 31-48. """ # make sure neither p nor q is 0 if p == 0 or q == 0: return [p, q] # make sure proper degrees d0 = degree(p, x) d1 = degree(q, x) if d0 == 0 and d1 == 0: return [p, q] if d1 > d0: d0, d1 = d1, d0 p, q = q, p if d0 > 0 and d1 == 0: return [p,q] # make sure LC(p) > 0 flag = 0 if LC(p,x) < 0: flag = 1 p = -p q = -q # initialize a0, a1 = p, q # the input polys sturm_seq = [a0, a1] # the output list a2 = -rem(a0, a1, domain=QQ) # first remainder d2 = degree(a2, x) # degree of a2 sturm_seq.append( a2 ) # main loop while d2 > 0: a0, a1, d0, d1 = a1, a2, d1, d2 # update polys and degrees a2 = -rem(a0, a1, domain=QQ) # new remainder d2 = degree(a2, x) # actual degree of a2 sturm_seq.append( a2 ) if flag: # change the sign of the sequence sturm_seq = [-i for i in sturm_seq] # gcd is of degree > 0 ? m = len(sturm_seq) if sturm_seq[m - 1] == nan or sturm_seq[m - 1] == 0: sturm_seq.pop(m - 1) return sturm_seq def sturm_amv(p, q, x, method=0): """ p, q are polynomials in Z[x] or Q[x]. It is assumed that degree(p, x) >= degree(q, x). Computes the (generalized) Sturm sequence of p and q in Z[x] or Q[x]. If q = diff(p, x, 1) it is the usual Sturm sequence. A. If method == 0, default, the remainder coefficients of the sequence are (in absolute value) ``modified'' subresultants, which for non-monic polynomials are greater than the coefficients of the corresponding subresultants by the factor Abs(LC(p)**( deg(p)- deg(q))). B. If method == 1, the remainder coefficients of the sequence are (in absolute value) subresultants, which for non-monic polynomials are smaller than the coefficients of the corresponding ``modified'' subresultants by the factor Abs( LC(p)**( deg(p)- deg(q)) ). If the Sturm sequence is complete, method=0 and LC( p ) > 0, then the coefficients of the polynomials in the sequence are ``modified'' subresultants. That is, they are determinants of appropriately selected submatrices of sylvester2, Sylvester's matrix of 1853. In this case the Sturm sequence coincides with the ``modified'' subresultant prs, of the polynomials p, q. If the Sturm sequence is incomplete and method=0 then the signs of the coefficients of the polynomials in the sequence may differ from the signs of the coefficients of the corresponding polynomials in the ``modified'' subresultant prs; however, the absolute values are the same. To compute the coefficients, no determinant evaluation takes place. Instead, we first compute the euclidean sequence of p and q using euclid_amv(p, q, x) and then: (a) change the signs of the remainders in the Euclidean sequence according to the pattern "-, -, +, +, -, -, +, +,..." (see Lemma 1 in the 1st reference or Theorem 3 in the 2nd reference) and (b) if method=0, assuming deg(p) > deg(q), we multiply the remainder coefficients of the Euclidean sequence times the factor Abs( LC(p)**( deg(p)- deg(q)) ) to make them modified subresultants. See also the function sturm_pg(p, q, x). References ========== 1. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``A Basic Result on the Theory of Subresultants.'' Serdica Journal of Computing 10 (2016), Νο.1, 31-48. 2. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``On the Remainders Obtained in Finding the Greatest Common Divisor of Two Polynomials.'' Serdica Journal of Computing 9(2) (2015), 123-138. 3. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``Subresultant Polynomial Remainder Sequences Obtained by Polynomial Divisions in Q[x] or in Z[x].'' Serdica Journal of Computing 10 (2016), Νο.3-4, 197-217. """ # compute the euclidean sequence prs = euclid_amv(p, q, x) # defensive if prs == [] or len(prs) == 2: return prs # the coefficients in prs are subresultants and hence are smaller # than the corresponding subresultants by the factor # Abs( LC(prs[0])**( deg(prs[0]) - deg(prs[1])) ); Theorem 2, 2nd reference. lcf = Abs( LC(prs[0])**( degree(prs[0], x) - degree(prs[1], x) ) ) # the signs of the first two polys in the sequence stay the same sturm_seq = [prs[0], prs[1]] # change the signs according to "-, -, +, +, -, -, +, +,..." # and multiply times lcf if needed flag = 0 m = len(prs) i = 2 while i <= m-1: if flag == 0: sturm_seq.append( - prs[i] ) i = i + 1 if i == m: break sturm_seq.append( - prs[i] ) i = i + 1 flag = 1 elif flag == 1: sturm_seq.append( prs[i] ) i = i + 1 if i == m: break sturm_seq.append( prs[i] ) i = i + 1 flag = 0 # subresultants or modified subresultants? if method == 0 and lcf > 1: aux_seq = [sturm_seq[0], sturm_seq[1]] for i in range(2, m): aux_seq.append(simplify(sturm_seq[i] * lcf )) sturm_seq = aux_seq return sturm_seq def euclid_pg(p, q, x): """ p, q are polynomials in Z[x] or Q[x]. It is assumed that degree(p, x) >= degree(q, x). Computes the Euclidean sequence of p and q in Z[x] or Q[x]. If the Euclidean sequence is complete the coefficients of the polynomials in the sequence are subresultants. That is, they are determinants of appropriately selected submatrices of sylvester1, Sylvester's matrix of 1840. In this case the Euclidean sequence coincides with the subresultant prs of the polynomials p, q. If the Euclidean sequence is incomplete the signs of the coefficients of the polynomials in the sequence may differ from the signs of the coefficients of the corresponding polynomials in the subresultant prs; however, the absolute values are the same. To compute the Euclidean sequence, no determinant evaluation takes place. We first compute the (generalized) Sturm sequence of p and q using sturm_pg(p, q, x, 1), in which case the coefficients are (in absolute value) equal to subresultants. Then we change the signs of the remainders in the Sturm sequence according to the pattern "-, -, +, +, -, -, +, +,..." ; see Lemma 1 in the 1st reference or Theorem 3 in the 2nd reference as well as the function sturm_pg(p, q, x). References ========== 1. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``A Basic Result on the Theory of Subresultants.'' Serdica Journal of Computing 10 (2016), Νο.1, 31-48. 2. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``On the Remainders Obtained in Finding the Greatest Common Divisor of Two Polynomials.'' Serdica Journal of Computing 9(2) (2015), 123-138. 3. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``Subresultant Polynomial Remainder Sequences Obtained by Polynomial Divisions in Q[x] or in Z[x].'' Serdica Journal of Computing 10 (2016), Νο.3-4, 197-217. """ # compute the sturmian sequence using the Pell-Gordon (or AMV) theorem # with the coefficients in the prs being (in absolute value) subresultants prs = sturm_pg(p, q, x, 1) ## any other method would do # defensive if prs == [] or len(prs) == 2: return prs # the signs of the first two polys in the sequence stay the same euclid_seq = [prs[0], prs[1]] # change the signs according to "-, -, +, +, -, -, +, +,..." flag = 0 m = len(prs) i = 2 while i <= m-1: if flag == 0: euclid_seq.append(- prs[i] ) i = i + 1 if i == m: break euclid_seq.append(- prs[i] ) i = i + 1 flag = 1 elif flag == 1: euclid_seq.append(prs[i] ) i = i + 1 if i == m: break euclid_seq.append(prs[i] ) i = i + 1 flag = 0 return euclid_seq def euclid_q(p, q, x): """ p, q are polynomials in Z[x] or Q[x]. It is assumed that degree(p, x) >= degree(q, x). Computes the Euclidean sequence of p and q in Q[x]. Polynomial divisions in Q[x] are performed, using the function rem(p, q, x). The coefficients of the polynomials in the Euclidean sequence can be uniquely determined from the corresponding coefficients of the polynomials found either in: (a) the ``modified'' subresultant polynomial remainder sequence, (references 1, 2) or in (b) the subresultant polynomial remainder sequence (references 3). References ========== 1. Pell A. J., R. L. Gordon. The Modified Remainders Obtained in Finding the Highest Common Factor of Two Polynomials. Annals of MatheMatics, Second Series, 18 (1917), No. 4, 188–193. 2. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``Sturm Sequences and Modified Subresultant Polynomial Remainder Sequences.'' Serdica Journal of Computing, Vol. 8, No 1, 29–46, 2014. 3. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``A Basic Result on the Theory of Subresultants.'' Serdica Journal of Computing 10 (2016), Νο.1, 31-48. """ # make sure neither p nor q is 0 if p == 0 or q == 0: return [p, q] # make sure proper degrees d0 = degree(p, x) d1 = degree(q, x) if d0 == 0 and d1 == 0: return [p, q] if d1 > d0: d0, d1 = d1, d0 p, q = q, p if d0 > 0 and d1 == 0: return [p,q] # make sure LC(p) > 0 flag = 0 if LC(p,x) < 0: flag = 1 p = -p q = -q # initialize a0, a1 = p, q # the input polys euclid_seq = [a0, a1] # the output list a2 = rem(a0, a1, domain=QQ) # first remainder d2 = degree(a2, x) # degree of a2 euclid_seq.append( a2 ) # main loop while d2 > 0: a0, a1, d0, d1 = a1, a2, d1, d2 # update polys and degrees a2 = rem(a0, a1, domain=QQ) # new remainder d2 = degree(a2, x) # actual degree of a2 euclid_seq.append( a2 ) if flag: # change the sign of the sequence euclid_seq = [-i for i in euclid_seq] # gcd is of degree > 0 ? m = len(euclid_seq) if euclid_seq[m - 1] == nan or euclid_seq[m - 1] == 0: euclid_seq.pop(m - 1) return euclid_seq def euclid_amv(f, g, x): """ f, g are polynomials in Z[x] or Q[x]. It is assumed that degree(f, x) >= degree(g, x). Computes the Euclidean sequence of p and q in Z[x] or Q[x]. If the Euclidean sequence is complete the coefficients of the polynomials in the sequence are subresultants. That is, they are determinants of appropriately selected submatrices of sylvester1, Sylvester's matrix of 1840. In this case the Euclidean sequence coincides with the subresultant prs, of the polynomials p, q. If the Euclidean sequence is incomplete the signs of the coefficients of the polynomials in the sequence may differ from the signs of the coefficients of the corresponding polynomials in the subresultant prs; however, the absolute values are the same. To compute the coefficients, no determinant evaluation takes place. Instead, polynomial divisions in Z[x] or Q[x] are performed, using the function rem_z(f, g, x); the coefficients of the remainders computed this way become subresultants with the help of the Collins-Brown-Traub formula for coefficient reduction. References ========== 1. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``A Basic Result on the Theory of Subresultants.'' Serdica Journal of Computing 10 (2016), Νο.1, 31-48. 2. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``Subresultant Polynomial remainder Sequences Obtained by Polynomial Divisions in Q[x] or in Z[x].'' Serdica Journal of Computing 10 (2016), Νο.3-4, 197-217. """ # make sure neither f nor g is 0 if f == 0 or g == 0: return [f, g] # make sure proper degrees d0 = degree(f, x) d1 = degree(g, x) if d0 == 0 and d1 == 0: return [f, g] if d1 > d0: d0, d1 = d1, d0 f, g = g, f if d0 > 0 and d1 == 0: return [f, g] # initialize a0 = f a1 = g euclid_seq = [a0, a1] deg_dif_p1, c = degree(a0, x) - degree(a1, x) + 1, -1 # compute the first polynomial of the prs i = 1 a2 = rem_z(a0, a1, x) / Abs( (-1)**deg_dif_p1 ) # first remainder euclid_seq.append( a2 ) d2 = degree(a2, x) # actual degree of a2 # main loop while d2 >= 1: a0, a1, d0, d1 = a1, a2, d1, d2 # update polys and degrees i += 1 sigma0 = -LC(a0) c = (sigma0**(deg_dif_p1 - 1)) / (c**(deg_dif_p1 - 2)) deg_dif_p1 = degree(a0, x) - d2 + 1 a2 = rem_z(a0, a1, x) / Abs( ((c**(deg_dif_p1 - 1)) * sigma0) ) euclid_seq.append( a2 ) d2 = degree(a2, x) # actual degree of a2 # gcd is of degree > 0 ? m = len(euclid_seq) if euclid_seq[m - 1] == nan or euclid_seq[m - 1] == 0: euclid_seq.pop(m - 1) return euclid_seq def modified_subresultants_pg(p, q, x): """ p, q are polynomials in Z[x] or Q[x]. It is assumed that degree(p, x) >= degree(q, x). Computes the ``modified'' subresultant prs of p and q in Z[x] or Q[x]; the coefficients of the polynomials in the sequence are ``modified'' subresultants. That is, they are determinants of appropriately selected submatrices of sylvester2, Sylvester's matrix of 1853. To compute the coefficients, no determinant evaluation takes place. Instead, polynomial divisions in Q[x] are performed, using the function rem(p, q, x); the coefficients of the remainders computed this way become ``modified'' subresultants with the help of the Pell-Gordon Theorem of 1917. If the ``modified'' subresultant prs is complete, and LC( p ) > 0, it coincides with the (generalized) Sturm sequence of the polynomials p, q. References ========== 1. Pell A. J., R. L. Gordon. The Modified Remainders Obtained in Finding the Highest Common Factor of Two Polynomials. Annals of MatheMatics, Second Series, 18 (1917), No. 4, 188–193. 2. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``Sturm Sequences and Modified Subresultant Polynomial Remainder Sequences.'' Serdica Journal of Computing, Vol. 8, No 1, 29–46, 2014. """ # make sure neither p nor q is 0 if p == 0 or q == 0: return [p, q] # make sure proper degrees d0 = degree(p,x) d1 = degree(q,x) if d0 == 0 and d1 == 0: return [p, q] if d1 > d0: d0, d1 = d1, d0 p, q = q, p if d0 > 0 and d1 == 0: return [p,q] # initialize k = var('k') # index in summation formula u_list = [] # of elements (-1)**u_i subres_l = [p, q] # mod. subr. prs output list a0, a1 = p, q # the input polys del0 = d0 - d1 # degree difference degdif = del0 # save it rho_1 = LC(a0) # lead. coeff (a0) # Initialize Pell-Gordon variables rho_list_minus_1 = sign( LC(a0, x)) # sign of LC(a0) rho1 = LC(a1, x) # leading coeff of a1 rho_list = [ sign(rho1)] # of signs p_list = [del0] # of degree differences u = summation(k, (k, 1, p_list[0])) # value of u u_list.append(u) # of u values v = sum(p_list) # v value # first remainder exp_deg = d1 - 1 # expected degree of a2 a2 = - rem(a0, a1, domain=QQ) # first remainder rho2 = LC(a2, x) # leading coeff of a2 d2 = degree(a2, x) # actual degree of a2 deg_diff_new = exp_deg - d2 # expected - actual degree del1 = d1 - d2 # degree difference # mul_fac is the factor by which a2 is multiplied to # get integer coefficients mul_fac_old = rho1**(del0 + del1 - deg_diff_new) # update Pell-Gordon variables p_list.append(1 + deg_diff_new) # deg_diff_new is 0 for complete seq # apply Pell-Gordon formula (7) in second reference num = 1 # numerator of fraction for k in range(len(u_list)): num *= (-1)**u_list[k] num = num * (-1)**v # denominator depends on complete / incomplete seq if deg_diff_new == 0: # complete seq den = 1 for k in range(len(rho_list)): den *= rho_list[k]**(p_list[k] + p_list[k + 1]) den = den * rho_list_minus_1 else: # incomplete seq den = 1 for k in range(len(rho_list)-1): den *= rho_list[k]**(p_list[k] + p_list[k + 1]) den = den * rho_list_minus_1 expo = (p_list[len(rho_list) - 1] + p_list[len(rho_list)] - deg_diff_new) den = den * rho_list[len(rho_list) - 1]**expo # the sign of the determinant depends on sg(num / den) if sign(num / den) > 0: subres_l.append( simplify(rho_1**degdif*a2* Abs(mul_fac_old) ) ) else: subres_l.append(- simplify(rho_1**degdif*a2* Abs(mul_fac_old) ) ) # update Pell-Gordon variables k = var('k') rho_list.append( sign(rho2)) u = summation(k, (k, 1, p_list[len(p_list) - 1])) u_list.append(u) v = sum(p_list) deg_diff_old=deg_diff_new # main loop while d2 > 0: a0, a1, d0, d1 = a1, a2, d1, d2 # update polys and degrees del0 = del1 # update degree difference exp_deg = d1 - 1 # new expected degree a2 = - rem(a0, a1, domain=QQ) # new remainder rho3 = LC(a2, x) # leading coeff of a2 d2 = degree(a2, x) # actual degree of a2 deg_diff_new = exp_deg - d2 # expected - actual degree del1 = d1 - d2 # degree difference # take into consideration the power # rho1**deg_diff_old that was "left out" expo_old = deg_diff_old # rho1 raised to this power expo_new = del0 + del1 - deg_diff_new # rho2 raised to this power mul_fac_new = rho2**(expo_new) * rho1**(expo_old) * mul_fac_old # update variables deg_diff_old, mul_fac_old = deg_diff_new, mul_fac_new rho1, rho2 = rho2, rho3 # update Pell-Gordon variables p_list.append(1 + deg_diff_new) # deg_diff_new is 0 for complete seq # apply Pell-Gordon formula (7) in second reference num = 1 # numerator for k in range(len(u_list)): num *= (-1)**u_list[k] num = num * (-1)**v # denominator depends on complete / incomplete seq if deg_diff_new == 0: # complete seq den = 1 for k in range(len(rho_list)): den *= rho_list[k]**(p_list[k] + p_list[k + 1]) den = den * rho_list_minus_1 else: # incomplete seq den = 1 for k in range(len(rho_list)-1): den *= rho_list[k]**(p_list[k] + p_list[k + 1]) den = den * rho_list_minus_1 expo = (p_list[len(rho_list) - 1] + p_list[len(rho_list)] - deg_diff_new) den = den * rho_list[len(rho_list) - 1]**expo # the sign of the determinant depends on sg(num / den) if sign(num / den) > 0: subres_l.append( simplify(rho_1**degdif*a2* Abs(mul_fac_old) ) ) else: subres_l.append(- simplify(rho_1**degdif*a2* Abs(mul_fac_old) ) ) # update Pell-Gordon variables k = var('k') rho_list.append( sign(rho2)) u = summation(k, (k, 1, p_list[len(p_list) - 1])) u_list.append(u) v = sum(p_list) # gcd is of degree > 0 ? m = len(subres_l) if subres_l[m - 1] == nan or subres_l[m - 1] == 0: subres_l.pop(m - 1) # LC( p ) < 0 m = len(subres_l) # list may be shorter now due to deg(gcd ) > 0 if LC( p ) < 0: aux_seq = [subres_l[0], subres_l[1]] for i in range(2, m): aux_seq.append(simplify(subres_l[i] * (-1) )) subres_l = aux_seq return subres_l def subresultants_pg(p, q, x): """ p, q are polynomials in Z[x] or Q[x]. It is assumed that degree(p, x) >= degree(q, x). Computes the subresultant prs of p and q in Z[x] or Q[x], from the modified subresultant prs of p and q. The coefficients of the polynomials in these two sequences differ only in sign and the factor LC(p)**( deg(p)- deg(q)) as stated in Theorem 2 of the reference. The coefficients of the polynomials in the output sequence are subresultants. That is, they are determinants of appropriately selected submatrices of sylvester1, Sylvester's matrix of 1840. If the subresultant prs is complete, then it coincides with the Euclidean sequence of the polynomials p, q. References ========== 1. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ‘‘On the Remainders Obtained in Finding the Greatest Common Divisor of Two Polynomials.'' Serdica Journal of Computing 9(2) (2015), 123-138. """ # compute the modified subresultant prs lst = modified_subresultants_pg(p,q,x) ## any other method would do # defensive if lst == [] or len(lst) == 2: return lst # the coefficients in lst are modified subresultants and, hence, are # greater than those of the corresponding subresultants by the factor # LC(lst[0])**( deg(lst[0]) - deg(lst[1])); see Theorem 2 in reference. lcf = LC(lst[0])**( degree(lst[0], x) - degree(lst[1], x) ) # Initialize the subresultant prs list subr_seq = [lst[0], lst[1]] # compute the degree sequences m_i and j_i of Theorem 2 in reference. deg_seq = [degree(Poly(poly, x), x) for poly in lst] deg = deg_seq[0] deg_seq_s = deg_seq[1:-1] m_seq = [m-1 for m in deg_seq_s] j_seq = [deg - m for m in m_seq] # compute the AMV factors of Theorem 2 in reference. fact = [(-1)**( j*(j-1)/S(2) ) for j in j_seq] # shortened list without the first two polys lst_s = lst[2:] # poly lst_s[k] is multiplied times fact[k], divided by lcf # and appended to the subresultant prs list m = len(fact) for k in range(m): if sign(fact[k]) == -1: subr_seq.append(-lst_s[k] / lcf) else: subr_seq.append(lst_s[k] / lcf) return subr_seq def subresultants_amv_q(p, q, x): """ p, q are polynomials in Z[x] or Q[x]. It is assumed that degree(p, x) >= degree(q, x). Computes the subresultant prs of p and q in Q[x]; the coefficients of the polynomials in the sequence are subresultants. That is, they are determinants of appropriately selected submatrices of sylvester1, Sylvester's matrix of 1840. To compute the coefficients, no determinant evaluation takes place. Instead, polynomial divisions in Q[x] are performed, using the function rem(p, q, x); the coefficients of the remainders computed this way become subresultants with the help of the Akritas-Malaschonok-Vigklas Theorem of 2015. If the subresultant prs is complete, then it coincides with the Euclidean sequence of the polynomials p, q. References ========== 1. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``A Basic Result on the Theory of Subresultants.'' Serdica Journal of Computing 10 (2016), Νο.1, 31-48. 2. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``Subresultant Polynomial remainder Sequences Obtained by Polynomial Divisions in Q[x] or in Z[x].'' Serdica Journal of Computing 10 (2016), Νο.3-4, 197-217. """ # make sure neither p nor q is 0 if p == 0 or q == 0: return [p, q] # make sure proper degrees d0 = degree(p, x) d1 = degree(q, x) if d0 == 0 and d1 == 0: return [p, q] if d1 > d0: d0, d1 = d1, d0 p, q = q, p if d0 > 0 and d1 == 0: return [p, q] # initialize i, s = 0, 0 # counters for remainders & odd elements p_odd_index_sum = 0 # contains the sum of p_1, p_3, etc subres_l = [p, q] # subresultant prs output list a0, a1 = p, q # the input polys sigma1 = LC(a1, x) # leading coeff of a1 p0 = d0 - d1 # degree difference if p0 % 2 == 1: s += 1 phi = floor( (s + 1) / 2 ) mul_fac = 1 d2 = d1 # main loop while d2 > 0: i += 1 a2 = rem(a0, a1, domain= QQ) # new remainder if i == 1: sigma2 = LC(a2, x) else: sigma3 = LC(a2, x) sigma1, sigma2 = sigma2, sigma3 d2 = degree(a2, x) p1 = d1 - d2 psi = i + phi + p_odd_index_sum # new mul_fac mul_fac = sigma1**(p0 + 1) * mul_fac ## compute the sign of the first fraction in formula (9) of the paper # numerator num = (-1)**psi # denominator den = sign(mul_fac) # the sign of the determinant depends on sign( num / den ) != 0 if sign(num / den) > 0: subres_l.append( simplify(expand(a2* Abs(mul_fac)))) else: subres_l.append(- simplify(expand(a2* Abs(mul_fac)))) ## bring into mul_fac the missing power of sigma if there was a degree gap if p1 - 1 > 0: mul_fac = mul_fac * sigma1**(p1 - 1) # update AMV variables a0, a1, d0, d1 = a1, a2, d1, d2 p0 = p1 if p0 % 2 ==1: s += 1 phi = floor( (s + 1) / 2 ) if i%2 == 1: p_odd_index_sum += p0 # p_i has odd index # gcd is of degree > 0 ? m = len(subres_l) if subres_l[m - 1] == nan or subres_l[m - 1] == 0: subres_l.pop(m - 1) return subres_l def compute_sign(base, expo): ''' base != 0 and expo >= 0 are integers; returns the sign of base**expo without evaluating the power itself! ''' sb = sign(base) if sb == 1: return 1 pe = expo % 2 if pe == 0: return -sb else: return sb def rem_z(p, q, x): ''' Intended mainly for p, q polynomials in Z[x] so that, on dividing p by q, the remainder will also be in Z[x]. (However, it also works fine for polynomials in Q[x].) It is assumed that degree(p, x) >= degree(q, x). It premultiplies p by the _absolute_ value of the leading coefficient of q, raised to the power deg(p) - deg(q) + 1 and then performs polynomial division in Q[x], using the function rem(p, q, x). By contrast the function prem(p, q, x) does _not_ use the absolute value of the leading coefficient of q. This results not only in ``messing up the signs'' of the Euclidean and Sturmian prs's as mentioned in the second reference, but also in violation of the main results of the first and third references --- Theorem 4 and Theorem 1 respectively. Theorems 4 and 1 establish a one-to-one correspondence between the Euclidean and the Sturmian prs of p, q, on one hand, and the subresultant prs of p, q, on the other. References ========== 1. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``On the Remainders Obtained in Finding the Greatest Common Divisor of Two Polynomials.'' Serdica Journal of Computing, 9(2) (2015), 123-138. 2. http://planetMath.org/sturmstheorem 3. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``A Basic Result on the Theory of Subresultants.'' Serdica Journal of Computing 10 (2016), Νο.1, 31-48. ''' if (p.as_poly().is_univariate and q.as_poly().is_univariate and p.as_poly().gens == q.as_poly().gens): delta = (degree(p, x) - degree(q, x) + 1) return rem(Abs(LC(q, x))**delta * p, q, x) else: return prem(p, q, x) def quo_z(p, q, x): """ Intended mainly for p, q polynomials in Z[x] so that, on dividing p by q, the quotient will also be in Z[x]. (However, it also works fine for polynomials in Q[x].) It is assumed that degree(p, x) >= degree(q, x). It premultiplies p by the _absolute_ value of the leading coefficient of q, raised to the power deg(p) - deg(q) + 1 and then performs polynomial division in Q[x], using the function quo(p, q, x). By contrast the function pquo(p, q, x) does _not_ use the absolute value of the leading coefficient of q. See also function rem_z(p, q, x) for additional comments and references. """ if (p.as_poly().is_univariate and q.as_poly().is_univariate and p.as_poly().gens == q.as_poly().gens): delta = (degree(p, x) - degree(q, x) + 1) return quo(Abs(LC(q, x))**delta * p, q, x) else: return pquo(p, q, x) def subresultants_amv(f, g, x): """ p, q are polynomials in Z[x] or Q[x]. It is assumed that degree(f, x) >= degree(g, x). Computes the subresultant prs of p and q in Z[x] or Q[x]; the coefficients of the polynomials in the sequence are subresultants. That is, they are determinants of appropriately selected submatrices of sylvester1, Sylvester's matrix of 1840. To compute the coefficients, no determinant evaluation takes place. Instead, polynomial divisions in Z[x] or Q[x] are performed, using the function rem_z(p, q, x); the coefficients of the remainders computed this way become subresultants with the help of the Akritas-Malaschonok-Vigklas Theorem of 2015 and the Collins-Brown- Traub formula for coefficient reduction. If the subresultant prs is complete, then it coincides with the Euclidean sequence of the polynomials p, q. References ========== 1. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``A Basic Result on the Theory of Subresultants.'' Serdica Journal of Computing 10 (2016), Νο.1, 31-48. 2. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``Subresultant Polynomial remainder Sequences Obtained by Polynomial Divisions in Q[x] or in Z[x].'' Serdica Journal of Computing 10 (2016), Νο.3-4, 197-217. """ # make sure neither f nor g is 0 if f == 0 or g == 0: return [f, g] # make sure proper degrees d0 = degree(f, x) d1 = degree(g, x) if d0 == 0 and d1 == 0: return [f, g] if d1 > d0: d0, d1 = d1, d0 f, g = g, f if d0 > 0 and d1 == 0: return [f, g] # initialize a0 = f a1 = g subres_l = [a0, a1] deg_dif_p1, c = degree(a0, x) - degree(a1, x) + 1, -1 # initialize AMV variables sigma1 = LC(a1, x) # leading coeff of a1 i, s = 0, 0 # counters for remainders & odd elements p_odd_index_sum = 0 # contains the sum of p_1, p_3, etc p0 = deg_dif_p1 - 1 if p0 % 2 == 1: s += 1 phi = floor( (s + 1) / 2 ) # compute the first polynomial of the prs i += 1 a2 = rem_z(a0, a1, x) / Abs( (-1)**deg_dif_p1 ) # first remainder sigma2 = LC(a2, x) # leading coeff of a2 d2 = degree(a2, x) # actual degree of a2 p1 = d1 - d2 # degree difference # sgn_den is the factor, the denominator 1st fraction of (9), # by which a2 is multiplied to get integer coefficients sgn_den = compute_sign( sigma1, p0 + 1 ) ## compute sign of the 1st fraction in formula (9) of the paper # numerator psi = i + phi + p_odd_index_sum num = (-1)**psi # denominator den = sgn_den # the sign of the determinant depends on sign(num / den) != 0 if sign(num / den) > 0: subres_l.append( a2 ) else: subres_l.append( -a2 ) # update AMV variable if p1 % 2 == 1: s += 1 # bring in the missing power of sigma if there was gap if p1 - 1 > 0: sgn_den = sgn_den * compute_sign( sigma1, p1 - 1 ) # main loop while d2 >= 1: phi = floor( (s + 1) / 2 ) if i%2 == 1: p_odd_index_sum += p1 # p_i has odd index a0, a1, d0, d1 = a1, a2, d1, d2 # update polys and degrees p0 = p1 # update degree difference i += 1 sigma0 = -LC(a0) c = (sigma0**(deg_dif_p1 - 1)) / (c**(deg_dif_p1 - 2)) deg_dif_p1 = degree(a0, x) - d2 + 1 a2 = rem_z(a0, a1, x) / Abs( ((c**(deg_dif_p1 - 1)) * sigma0) ) sigma3 = LC(a2, x) # leading coeff of a2 d2 = degree(a2, x) # actual degree of a2 p1 = d1 - d2 # degree difference psi = i + phi + p_odd_index_sum # update variables sigma1, sigma2 = sigma2, sigma3 # new sgn_den sgn_den = compute_sign( sigma1, p0 + 1 ) * sgn_den # compute the sign of the first fraction in formula (9) of the paper # numerator num = (-1)**psi # denominator den = sgn_den # the sign of the determinant depends on sign( num / den ) != 0 if sign(num / den) > 0: subres_l.append( a2 ) else: subres_l.append( -a2 ) # update AMV variable if p1 % 2 ==1: s += 1 # bring in the missing power of sigma if there was gap if p1 - 1 > 0: sgn_den = sgn_den * compute_sign( sigma1, p1 - 1 ) # gcd is of degree > 0 ? m = len(subres_l) if subres_l[m - 1] == nan or subres_l[m - 1] == 0: subres_l.pop(m - 1) return subres_l def modified_subresultants_amv(p, q, x): """ p, q are polynomials in Z[x] or Q[x]. It is assumed that degree(p, x) >= degree(q, x). Computes the modified subresultant prs of p and q in Z[x] or Q[x], from the subresultant prs of p and q. The coefficients of the polynomials in the two sequences differ only in sign and the factor LC(p)**( deg(p)- deg(q)) as stated in Theorem 2 of the reference. The coefficients of the polynomials in the output sequence are modified subresultants. That is, they are determinants of appropriately selected submatrices of sylvester2, Sylvester's matrix of 1853. If the modified subresultant prs is complete, and LC( p ) > 0, it coincides with the (generalized) Sturm's sequence of the polynomials p, q. References ========== 1. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ‘‘On the Remainders Obtained in Finding the Greatest Common Divisor of Two Polynomials.'' Serdica Journal of Computing, Serdica Journal of Computing, 9(2) (2015), 123-138. """ # compute the subresultant prs lst = subresultants_amv(p,q,x) ## any other method would do # defensive if lst == [] or len(lst) == 2: return lst # the coefficients in lst are subresultants and, hence, smaller than those # of the corresponding modified subresultants by the factor # LC(lst[0])**( deg(lst[0]) - deg(lst[1])); see Theorem 2. lcf = LC(lst[0])**( degree(lst[0], x) - degree(lst[1], x) ) # Initialize the modified subresultant prs list subr_seq = [lst[0], lst[1]] # compute the degree sequences m_i and j_i of Theorem 2 deg_seq = [degree(Poly(poly, x), x) for poly in lst] deg = deg_seq[0] deg_seq_s = deg_seq[1:-1] m_seq = [m-1 for m in deg_seq_s] j_seq = [deg - m for m in m_seq] # compute the AMV factors of Theorem 2 fact = [(-1)**( j*(j-1)/S(2) ) for j in j_seq] # shortened list without the first two polys lst_s = lst[2:] # poly lst_s[k] is multiplied times fact[k] and times lcf # and appended to the subresultant prs list m = len(fact) for k in range(m): if sign(fact[k]) == -1: subr_seq.append( simplify(-lst_s[k] * lcf) ) else: subr_seq.append( simplify(lst_s[k] * lcf) ) return subr_seq def correct_sign(deg_f, deg_g, s1, rdel, cdel): """ Used in various subresultant prs algorithms. Evaluates the determinant, (a.k.a. subresultant) of a properly selected submatrix of s1, Sylvester's matrix of 1840, to get the correct sign and value of the leading coefficient of a given polynomial remainder. deg_f, deg_g are the degrees of the original polynomials p, q for which the matrix s1 = sylvester(p, q, x, 1) was constructed. rdel denotes the expected degree of the remainder; it is the number of rows to be deleted from each group of rows in s1 as described in the reference below. cdel denotes the expected degree minus the actual degree of the remainder; it is the number of columns to be deleted --- starting with the last column forming the square matrix --- from the matrix resulting after the row deletions. References ========== Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``Sturm Sequences and Modified Subresultant Polynomial Remainder Sequences.'' Serdica Journal of Computing, Vol. 8, No 1, 29–46, 2014. """ M = s1[:, :] # copy of matrix s1 # eliminate rdel rows from the first deg_g rows for i in range(M.rows - deg_f - 1, M.rows - deg_f - rdel - 1, -1): M.row_del(i) # eliminate rdel rows from the last deg_f rows for i in range(M.rows - 1, M.rows - rdel - 1, -1): M.row_del(i) # eliminate cdel columns for i in range(cdel): M.col_del(M.rows - 1) # define submatrix Md = M[:, 0: M.rows] return Md.det() def subresultants_rem(p, q, x): """ p, q are polynomials in Z[x] or Q[x]. It is assumed that degree(p, x) >= degree(q, x). Computes the subresultant prs of p and q in Z[x] or Q[x]; the coefficients of the polynomials in the sequence are subresultants. That is, they are determinants of appropriately selected submatrices of sylvester1, Sylvester's matrix of 1840. To compute the coefficients polynomial divisions in Q[x] are performed, using the function rem(p, q, x). The coefficients of the remainders computed this way become subresultants by evaluating one subresultant per remainder --- that of the leading coefficient. This way we obtain the correct sign and value of the leading coefficient of the remainder and we easily ``force'' the rest of the coefficients to become subresultants. If the subresultant prs is complete, then it coincides with the Euclidean sequence of the polynomials p, q. References ========== 1. Akritas, A. G.:``Three New Methods for Computing Subresultant Polynomial Remainder Sequences (PRS’s).'' Serdica Journal of Computing 9(1) (2015), 1-26. """ # make sure neither p nor q is 0 if p == 0 or q == 0: return [p, q] # make sure proper degrees f, g = p, q n = deg_f = degree(f, x) m = deg_g = degree(g, x) if n == 0 and m == 0: return [f, g] if n < m: n, m, deg_f, deg_g, f, g = m, n, deg_g, deg_f, g, f if n > 0 and m == 0: return [f, g] # initialize s1 = sylvester(f, g, x, 1) sr_list = [f, g] # subresultant list # main loop while deg_g > 0: r = rem(p, q, x) d = degree(r, x) if d < 0: return sr_list # make coefficients subresultants evaluating ONE determinant exp_deg = deg_g - 1 # expected degree sign_value = correct_sign(n, m, s1, exp_deg, exp_deg - d) r = simplify((r / LC(r, x)) * sign_value) # append poly with subresultant coeffs sr_list.append(r) # update degrees and polys deg_f, deg_g = deg_g, d p, q = q, r # gcd is of degree > 0 ? m = len(sr_list) if sr_list[m - 1] == nan or sr_list[m - 1] == 0: sr_list.pop(m - 1) return sr_list def pivot(M, i, j): ''' M is a matrix, and M[i, j] specifies the pivot element. All elements below M[i, j], in the j-th column, will be zeroed, if they are not already 0, according to Dodgson-Bareiss' integer preserving transformations. References ========== 1. Akritas, A. G.: ``A new method for computing polynomial greatest common divisors and polynomial remainder sequences.'' Numerische MatheMatik 52, 119-127, 1988. 2. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``On a Theorem by Van Vleck Regarding Sturm Sequences.'' Serdica Journal of Computing, 7, No 4, 101–134, 2013. ''' ma = M[:, :] # copy of matrix M rs = ma.rows # No. of rows cs = ma.cols # No. of cols for r in range(i+1, rs): if ma[r, j] != 0: for c in range(j + 1, cs): ma[r, c] = ma[i, j] * ma[r, c] - ma[i, c] * ma[r, j] ma[r, j] = 0 return ma def rotate_r(L, k): ''' Rotates right by k. L is a row of a matrix or a list. ''' ll = list(L) if ll == []: return [] for i in range(k): el = ll.pop(len(ll) - 1) ll.insert(0, el) return ll if type(L) is list else Matrix([ll]) def rotate_l(L, k): ''' Rotates left by k. L is a row of a matrix or a list. ''' ll = list(L) if ll == []: return [] for i in range(k): el = ll.pop(0) ll.insert(len(ll) - 1, el) return ll if type(L) is list else Matrix([ll]) def row2poly(row, deg, x): ''' Converts the row of a matrix to a poly of degree deg and variable x. Some entries at the beginning and/or at the end of the row may be zero. ''' k = 0 poly = [] leng = len(row) # find the beginning of the poly ; i.e. the first # non-zero element of the row while row[k] == 0: k = k + 1 # append the next deg + 1 elements to poly for j in range( deg + 1): if k + j <= leng: poly.append(row[k + j]) return Poly(poly, x) def create_ma(deg_f, deg_g, row1, row2, col_num): ''' Creates a ``small'' matrix M to be triangularized. deg_f, deg_g are the degrees of the divident and of the divisor polynomials respectively, deg_g > deg_f. The coefficients of the divident poly are the elements in row2 and those of the divisor poly are the elements in row1. col_num defines the number of columns of the matrix M. ''' if deg_g - deg_f >= 1: print('Reverse degrees') return m = zeros(deg_f - deg_g + 2, col_num) for i in range(deg_f - deg_g + 1): m[i, :] = rotate_r(row1, i) m[deg_f - deg_g + 1, :] = row2 return m def find_degree(M, deg_f): ''' Finds the degree of the poly corresponding (after triangularization) to the _last_ row of the ``small'' matrix M, created by create_ma(). deg_f is the degree of the divident poly. If _last_ row is all 0's returns None. ''' j = deg_f for i in range(0, M.cols): if M[M.rows - 1, i] == 0: j = j - 1 else: return j if j >= 0 else 0 def final_touches(s2, r, deg_g): """ s2 is sylvester2, r is the row pointer in s2, deg_g is the degree of the poly last inserted in s2. After a gcd of degree > 0 has been found with Van Vleck's method, and was inserted into s2, if its last term is not in the last column of s2, then it is inserted as many times as needed, rotated right by one each time, until the condition is met. """ R = s2.row(r-1) # find the first non zero term for i in range(s2.cols): if R[0,i] == 0: continue else: break # missing rows until last term is in last column mr = s2.cols - (i + deg_g + 1) # insert them by replacing the existing entries in the row i = 0 while mr != 0 and r + i < s2.rows : s2[r + i, : ] = rotate_r(R, i + 1) i += 1 mr -= 1 return s2 def subresultants_vv(p, q, x, method = 0): """ p, q are polynomials in Z[x] (intended) or Q[x]. It is assumed that degree(p, x) >= degree(q, x). Computes the subresultant prs of p, q by triangularizing, in Z[x] or in Q[x], all the smaller matrices encountered in the process of triangularizing sylvester2, Sylvester's matrix of 1853; see references 1 and 2 for Van Vleck's method. With each remainder, sylvester2 gets updated and is prepared to be printed if requested. If sylvester2 has small dimensions and you want to see the final, triangularized matrix use this version with method=1; otherwise, use either this version with method=0 (default) or the faster version, subresultants_vv_2(p, q, x), where sylvester2 is used implicitly. Sylvester's matrix sylvester1 is also used to compute one subresultant per remainder; namely, that of the leading coefficient, in order to obtain the correct sign and to force the remainder coefficients to become subresultants. If the subresultant prs is complete, then it coincides with the Euclidean sequence of the polynomials p, q. If the final, triangularized matrix s2 is printed, then: (a) if deg(p) - deg(q) > 1 or deg( gcd(p, q) ) > 0, several of the last rows in s2 will remain unprocessed; (b) if deg(p) - deg(q) == 0, p will not appear in the final matrix. References ========== 1. Akritas, A. G.: ``A new method for computing polynomial greatest common divisors and polynomial remainder sequences.'' Numerische MatheMatik 52, 119-127, 1988. 2. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``On a Theorem by Van Vleck Regarding Sturm Sequences.'' Serdica Journal of Computing, 7, No 4, 101–134, 2013. 3. Akritas, A. G.:``Three New Methods for Computing Subresultant Polynomial Remainder Sequences (PRS’s).'' Serdica Journal of Computing 9(1) (2015), 1-26. """ # make sure neither p nor q is 0 if p == 0 or q == 0: return [p, q] # make sure proper degrees f, g = p, q n = deg_f = degree(f, x) m = deg_g = degree(g, x) if n == 0 and m == 0: return [f, g] if n < m: n, m, deg_f, deg_g, f, g = m, n, deg_g, deg_f, g, f if n > 0 and m == 0: return [f, g] # initialize s1 = sylvester(f, g, x, 1) s2 = sylvester(f, g, x, 2) sr_list = [f, g] col_num = 2 * n # columns in s2 # make two rows (row0, row1) of poly coefficients row0 = Poly(f, x, domain = QQ).all_coeffs() leng0 = len(row0) for i in range(col_num - leng0): row0.append(0) row0 = Matrix([row0]) row1 = Poly(g,x, domain = QQ).all_coeffs() leng1 = len(row1) for i in range(col_num - leng1): row1.append(0) row1 = Matrix([row1]) # row pointer for deg_f - deg_g == 1; may be reset below r = 2 # modify first rows of s2 matrix depending on poly degrees if deg_f - deg_g > 1: r = 1 # replacing the existing entries in the rows of s2, # insert row0 (deg_f - deg_g - 1) times, rotated each time for i in range(deg_f - deg_g - 1): s2[r + i, : ] = rotate_r(row0, i + 1) r = r + deg_f - deg_g - 1 # insert row1 (deg_f - deg_g) times, rotated each time for i in range(deg_f - deg_g): s2[r + i, : ] = rotate_r(row1, r + i) r = r + deg_f - deg_g if deg_f - deg_g == 0: r = 0 # main loop while deg_g > 0: # create a small matrix M, and triangularize it; M = create_ma(deg_f, deg_g, row1, row0, col_num) # will need only the first and last rows of M for i in range(deg_f - deg_g + 1): M1 = pivot(M, i, i) M = M1[:, :] # treat last row of M as poly; find its degree d = find_degree(M, deg_f) if d == None: break exp_deg = deg_g - 1 # evaluate one determinant & make coefficients subresultants sign_value = correct_sign(n, m, s1, exp_deg, exp_deg - d) poly = row2poly(M[M.rows - 1, :], d, x) temp2 = LC(poly, x) poly = simplify((poly / temp2) * sign_value) # update s2 by inserting first row of M as needed row0 = M[0, :] for i in range(deg_g - d): s2[r + i, :] = rotate_r(row0, r + i) r = r + deg_g - d # update s2 by inserting last row of M as needed row1 = rotate_l(M[M.rows - 1, :], deg_f - d) row1 = (row1 / temp2) * sign_value for i in range(deg_g - d): s2[r + i, :] = rotate_r(row1, r + i) r = r + deg_g - d # update degrees deg_f, deg_g = deg_g, d # append poly with subresultant coeffs sr_list.append(poly) # final touches to print the s2 matrix if method != 0 and s2.rows > 2: s2 = final_touches(s2, r, deg_g) pprint(s2) elif method != 0 and s2.rows == 2: s2[1, :] = rotate_r(s2.row(1), 1) pprint(s2) return sr_list def subresultants_vv_2(p, q, x): """ p, q are polynomials in Z[x] (intended) or Q[x]. It is assumed that degree(p, x) >= degree(q, x). Computes the subresultant prs of p, q by triangularizing, in Z[x] or in Q[x], all the smaller matrices encountered in the process of triangularizing sylvester2, Sylvester's matrix of 1853; see references 1 and 2 for Van Vleck's method. If the sylvester2 matrix has big dimensions use this version, where sylvester2 is used implicitly. If you want to see the final, triangularized matrix sylvester2, then use the first version, subresultants_vv(p, q, x, 1). sylvester1, Sylvester's matrix of 1840, is also used to compute one subresultant per remainder; namely, that of the leading coefficient, in order to obtain the correct sign and to ``force'' the remainder coefficients to become subresultants. If the subresultant prs is complete, then it coincides with the Euclidean sequence of the polynomials p, q. References ========== 1. Akritas, A. G.: ``A new method for computing polynomial greatest common divisors and polynomial remainder sequences.'' Numerische MatheMatik 52, 119-127, 1988. 2. Akritas, A. G., G.I. Malaschonok and P.S. Vigklas: ``On a Theorem by Van Vleck Regarding Sturm Sequences.'' Serdica Journal of Computing, 7, No 4, 101–134, 2013. 3. Akritas, A. G.:``Three New Methods for Computing Subresultant Polynomial Remainder Sequences (PRS’s).'' Serdica Journal of Computing 9(1) (2015), 1-26. """ # make sure neither p nor q is 0 if p == 0 or q == 0: return [p, q] # make sure proper degrees f, g = p, q n = deg_f = degree(f, x) m = deg_g = degree(g, x) if n == 0 and m == 0: return [f, g] if n < m: n, m, deg_f, deg_g, f, g = m, n, deg_g, deg_f, g, f if n > 0 and m == 0: return [f, g] # initialize s1 = sylvester(f, g, x, 1) sr_list = [f, g] # subresultant list col_num = 2 * n # columns in sylvester2 # make two rows (row0, row1) of poly coefficients row0 = Poly(f, x, domain = QQ).all_coeffs() leng0 = len(row0) for i in range(col_num - leng0): row0.append(0) row0 = Matrix([row0]) row1 = Poly(g,x, domain = QQ).all_coeffs() leng1 = len(row1) for i in range(col_num - leng1): row1.append(0) row1 = Matrix([row1]) # main loop while deg_g > 0: # create a small matrix M, and triangularize it M = create_ma(deg_f, deg_g, row1, row0, col_num) for i in range(deg_f - deg_g + 1): M1 = pivot(M, i, i) M = M1[:, :] # treat last row of M as poly; find its degree d = find_degree(M, deg_f) if d == None: return sr_list exp_deg = deg_g - 1 # evaluate one determinant & make coefficients subresultants sign_value = correct_sign(n, m, s1, exp_deg, exp_deg - d) poly = row2poly(M[M.rows - 1, :], d, x) poly = simplify((poly / LC(poly, x)) * sign_value) # append poly with subresultant coeffs sr_list.append(poly) # update degrees and rows deg_f, deg_g = deg_g, d row0 = row1 row1 = Poly(poly, x, domain = QQ).all_coeffs() leng1 = len(row1) for i in range(col_num - leng1): row1.append(0) row1 = Matrix([row1]) return sr_list

2ea0842d270282ea85c2f02054176591e4b368df1488aca09cd606d72ce015aa

"""Sparse polynomial rings. """ from __future__ import print_function, division from operator import add, mul, lt, le, gt, ge from types import GeneratorType from sympy.core.compatibility import is_sequence, reduce, string_types, range from sympy.core.expr import Expr from sympy.core.numbers import igcd, oo from sympy.core.symbol import Symbol, symbols as _symbols from sympy.core.sympify import CantSympify, sympify from sympy.ntheory.multinomial import multinomial_coefficients from sympy.polys.compatibility import IPolys from sympy.polys.constructor import construct_domain from sympy.polys.densebasic import dmp_to_dict, dmp_from_dict from sympy.polys.domains.domainelement import DomainElement from sympy.polys.domains.polynomialring import PolynomialRing from sympy.polys.heuristicgcd import heugcd from sympy.polys.monomials import MonomialOps from sympy.polys.orderings import lex from sympy.polys.polyerrors import ( CoercionFailed, GeneratorsError, ExactQuotientFailed, MultivariatePolynomialError) from sympy.polys.polyoptions import (Domain as DomainOpt, Order as OrderOpt, build_options) from sympy.polys.polyutils import (expr_from_dict, _dict_reorder, _parallel_dict_from_expr) from sympy.printing.defaults import DefaultPrinting from sympy.utilities import public from sympy.utilities.magic import pollute @public def ring(symbols, domain, order=lex): """Construct a polynomial ring returning ``(ring, x_1, ..., x_n)``. Parameters ========== symbols : str Symbol/Expr or sequence of str, Symbol/Expr (non-empty) domain : :class: `Domain` or coercible order : :class:, optional `Order` or coercible, optional, defaults to ``lex`` Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> from sympy.polys.orderings import lex >>> R, x, y, z = ring("x,y,z", ZZ, lex) >>> R Polynomial ring in x, y, z over ZZ with lex order >>> x + y + z x + y + z >>> type(_) <class 'sympy.polys.rings.PolyElement'> """ _ring = PolyRing(symbols, domain, order) return (_ring,) + _ring.gens @public def xring(symbols, domain, order=lex): """Construct a polynomial ring returning ``(ring, (x_1, ..., x_n))``. Parameters ========== symbols : str Symbol/Expr or sequence of str, Symbol/Expr (non-empty) domain : :class: `Domain` or coercible order : :class:, optional `Order` or coercible, optional, defaults to ``lex`` Examples ======== >>> from sympy.polys.rings import xring >>> from sympy.polys.domains import ZZ >>> from sympy.polys.orderings import lex >>> R, (x, y, z) = xring("x,y,z", ZZ, lex) >>> R Polynomial ring in x, y, z over ZZ with lex order >>> x + y + z x + y + z >>> type(_) <class 'sympy.polys.rings.PolyElement'> """ _ring = PolyRing(symbols, domain, order) return (_ring, _ring.gens) @public def vring(symbols, domain, order=lex): """Construct a polynomial ring and inject ``x_1, ..., x_n`` into the global namespace. Parameters ========== symbols : str Symbol/Expr or sequence of str, Symbol/Expr (non-empty) domain : :class: `Domain` or coercible order : :class:, optional `Order` or coercible, optional, defaults to ``lex`` Examples ======== >>> from sympy.polys.rings import vring >>> from sympy.polys.domains import ZZ >>> from sympy.polys.orderings import lex >>> vring("x,y,z", ZZ, lex) Polynomial ring in x, y, z over ZZ with lex order >>> x + y + z x + y + z >>> type(_) <class 'sympy.polys.rings.PolyElement'> """ _ring = PolyRing(symbols, domain, order) pollute([ sym.name for sym in _ring.symbols ], _ring.gens) return _ring @public def sring(exprs, *symbols, **options): """Construct a ring deriving generators and domain from options and input expressions. Parameters ========== exprs : :class: `Expr` or sequence of :class:`Expr` (sympifiable) symbols : sequence of :class:`Symbol`/:class:`Expr` options : keyword arguments understood by :class:`Options` Examples ======== >>> from sympy.core import symbols >>> from sympy.polys.rings import sring >>> from sympy.polys.domains import ZZ >>> from sympy.polys.orderings import lex >>> x, y, z = symbols("x,y,z") >>> R, f = sring(x + 2*y + 3*z) >>> R Polynomial ring in x, y, z over ZZ with lex order >>> f x + 2*y + 3*z >>> type(_) <class 'sympy.polys.rings.PolyElement'> """ single = False if not is_sequence(exprs): exprs, single = [exprs], True exprs = list(map(sympify, exprs)) opt = build_options(symbols, options) # TODO: rewrite this so that it doesn't use expand() (see poly()). reps, opt = _parallel_dict_from_expr(exprs, opt) if opt.domain is None: # NOTE: this is inefficient because construct_domain() automatically # performs conversion to the target domain. It shouldn't do this. coeffs = sum([ list(rep.values()) for rep in reps ], []) opt.domain, _ = construct_domain(coeffs, opt=opt) _ring = PolyRing(opt.gens, opt.domain, opt.order) polys = list(map(_ring.from_dict, reps)) if single: return (_ring, polys[0]) else: return (_ring, polys) def _parse_symbols(symbols): if isinstance(symbols, string_types): return _symbols(symbols, seq=True) if symbols else () elif isinstance(symbols, Expr): return (symbols,) elif is_sequence(symbols): if all(isinstance(s, string_types) for s in symbols): return _symbols(symbols) elif all(isinstance(s, Expr) for s in symbols): return symbols raise GeneratorsError("expected a string, Symbol or expression or a non-empty sequence of strings, Symbols or expressions") _ring_cache = {} class PolyRing(DefaultPrinting, IPolys): """Multivariate distributed polynomial ring. """ def __new__(cls, symbols, domain, order=lex): symbols = tuple(_parse_symbols(symbols)) ngens = len(symbols) domain = DomainOpt.preprocess(domain) order = OrderOpt.preprocess(order) _hash_tuple = (cls.__name__, symbols, ngens, domain, order) obj = _ring_cache.get(_hash_tuple) if obj is None: if domain.is_Composite and set(symbols) & set(domain.symbols): raise GeneratorsError("polynomial ring and it's ground domain share generators") obj = object.__new__(cls) obj._hash_tuple = _hash_tuple obj._hash = hash(_hash_tuple) obj.dtype = type("PolyElement", (PolyElement,), {"ring": obj}) obj.symbols = symbols obj.ngens = ngens obj.domain = domain obj.order = order obj.zero_monom = (0,)*ngens obj.gens = obj._gens() obj._gens_set = set(obj.gens) obj._one = [(obj.zero_monom, domain.one)] if ngens: # These expect monomials in at least one variable codegen = MonomialOps(ngens) obj.monomial_mul = codegen.mul() obj.monomial_pow = codegen.pow() obj.monomial_mulpow = codegen.mulpow() obj.monomial_ldiv = codegen.ldiv() obj.monomial_div = codegen.div() obj.monomial_lcm = codegen.lcm() obj.monomial_gcd = codegen.gcd() else: monunit = lambda a, b: () obj.monomial_mul = monunit obj.monomial_pow = monunit obj.monomial_mulpow = lambda a, b, c: () obj.monomial_ldiv = monunit obj.monomial_div = monunit obj.monomial_lcm = monunit obj.monomial_gcd = monunit if order is lex: obj.leading_expv = lambda f: max(f) else: obj.leading_expv = lambda f: max(f, key=order) for symbol, generator in zip(obj.symbols, obj.gens): if isinstance(symbol, Symbol): name = symbol.name if not hasattr(obj, name): setattr(obj, name, generator) _ring_cache[_hash_tuple] = obj return obj def _gens(self): """Return a list of polynomial generators. """ one = self.domain.one _gens = [] for i in range(self.ngens): expv = self.monomial_basis(i) poly = self.zero poly[expv] = one _gens.append(poly) return tuple(_gens) def __getnewargs__(self): return (self.symbols, self.domain, self.order) def __getstate__(self): state = self.__dict__.copy() del state["leading_expv"] for key, value in state.items(): if key.startswith("monomial_"): del state[key] return state def __hash__(self): return self._hash def __eq__(self, other): return isinstance(other, PolyRing) and \ (self.symbols, self.domain, self.ngens, self.order) == \ (other.symbols, other.domain, other.ngens, other.order) def __ne__(self, other): return not self == other def clone(self, symbols=None, domain=None, order=None): return self.__class__(symbols or self.symbols, domain or self.domain, order or self.order) def monomial_basis(self, i): """Return the ith-basis element. """ basis = [0]*self.ngens basis[i] = 1 return tuple(basis) @property def zero(self): return self.dtype() @property def one(self): return self.dtype(self._one) def domain_new(self, element, orig_domain=None): return self.domain.convert(element, orig_domain) def ground_new(self, coeff): return self.term_new(self.zero_monom, coeff) def term_new(self, monom, coeff): coeff = self.domain_new(coeff) poly = self.zero if coeff: poly[monom] = coeff return poly def ring_new(self, element): if isinstance(element, PolyElement): if self == element.ring: return element elif isinstance(self.domain, PolynomialRing) and self.domain.ring == element.ring: return self.ground_new(element) else: raise NotImplementedError("conversion") elif isinstance(element, string_types): raise NotImplementedError("parsing") elif isinstance(element, dict): return self.from_dict(element) elif isinstance(element, list): try: return self.from_terms(element) except ValueError: return self.from_list(element) elif isinstance(element, Expr): return self.from_expr(element) else: return self.ground_new(element) __call__ = ring_new def from_dict(self, element): domain_new = self.domain_new poly = self.zero for monom, coeff in element.items(): coeff = domain_new(coeff) if coeff: poly[monom] = coeff return poly def from_terms(self, element): return self.from_dict(dict(element)) def from_list(self, element): return self.from_dict(dmp_to_dict(element, self.ngens-1, self.domain)) def _rebuild_expr(self, expr, mapping): domain = self.domain def _rebuild(expr): generator = mapping.get(expr) if generator is not None: return generator elif expr.is_Add: return reduce(add, list(map(_rebuild, expr.args))) elif expr.is_Mul: return reduce(mul, list(map(_rebuild, expr.args))) elif expr.is_Pow and expr.exp.is_Integer and expr.exp >= 0: return _rebuild(expr.base)**int(expr.exp) else: return domain.convert(expr) return _rebuild(sympify(expr)) def from_expr(self, expr): mapping = dict(list(zip(self.symbols, self.gens))) try: poly = self._rebuild_expr(expr, mapping) except CoercionFailed: raise ValueError("expected an expression convertible to a polynomial in %s, got %s" % (self, expr)) else: return self.ring_new(poly) def index(self, gen): """Compute index of ``gen`` in ``self.gens``. """ if gen is None: if self.ngens: i = 0 else: i = -1 # indicate impossible choice elif isinstance(gen, int): i = gen if 0 <= i and i < self.ngens: pass elif -self.ngens <= i and i <= -1: i = -i - 1 else: raise ValueError("invalid generator index: %s" % gen) elif isinstance(gen, self.dtype): try: i = self.gens.index(gen) except ValueError: raise ValueError("invalid generator: %s" % gen) elif isinstance(gen, string_types): try: i = self.symbols.index(gen) except ValueError: raise ValueError("invalid generator: %s" % gen) else: raise ValueError("expected a polynomial generator, an integer, a string or None, got %s" % gen) return i def drop(self, *gens): """Remove specified generators from this ring. """ indices = set(map(self.index, gens)) symbols = [ s for i, s in enumerate(self.symbols) if i not in indices ] if not symbols: return self.domain else: return self.clone(symbols=symbols) def __getitem__(self, key): symbols = self.symbols[key] if not symbols: return self.domain else: return self.clone(symbols=symbols) def to_ground(self): # TODO: should AlgebraicField be a Composite domain? if self.domain.is_Composite or hasattr(self.domain, 'domain'): return self.clone(domain=self.domain.domain) else: raise ValueError("%s is not a composite domain" % self.domain) def to_domain(self): return PolynomialRing(self) def to_field(self): from sympy.polys.fields import FracField return FracField(self.symbols, self.domain, self.order) @property def is_univariate(self): return len(self.gens) == 1 @property def is_multivariate(self): return len(self.gens) > 1 def add(self, *objs): """ Add a sequence of polynomials or containers of polynomials. Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> R, x = ring("x", ZZ) >>> R.add([ x**2 + 2*i + 3 for i in range(4) ]) 4*x**2 + 24 >>> _.factor_list() (4, [(x**2 + 6, 1)]) """ p = self.zero for obj in objs: if is_sequence(obj, include=GeneratorType): p += self.add(*obj) else: p += obj return p def mul(self, *objs): """ Multiply a sequence of polynomials or containers of polynomials. Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> R, x = ring("x", ZZ) >>> R.mul([ x**2 + 2*i + 3 for i in range(4) ]) x**8 + 24*x**6 + 206*x**4 + 744*x**2 + 945 >>> _.factor_list() (1, [(x**2 + 3, 1), (x**2 + 5, 1), (x**2 + 7, 1), (x**2 + 9, 1)]) """ p = self.one for obj in objs: if is_sequence(obj, include=GeneratorType): p *= self.mul(*obj) else: p *= obj return p def drop_to_ground(self, *gens): r""" Remove specified generators from the ring and inject them into its domain. """ indices = set(map(self.index, gens)) symbols = [s for i, s in enumerate(self.symbols) if i not in indices] gens = [gen for i, gen in enumerate(self.gens) if i not in indices] if not symbols: return self else: return self.clone(symbols=symbols, domain=self.drop(*gens)) def compose(self, other): """Add the generators of ``other`` to ``self``""" if self != other: syms = set(self.symbols).union(set(other.symbols)) return self.clone(symbols=list(syms)) else: return self def add_gens(self, symbols): """Add the elements of ``symbols`` as generators to ``self``""" syms = set(self.symbols).union(set(symbols)) return self.clone(symbols=list(syms)) class PolyElement(DomainElement, DefaultPrinting, CantSympify, dict): """Element of multivariate distributed polynomial ring. """ def new(self, init): return self.__class__(init) def parent(self): return self.ring.to_domain() def __getnewargs__(self): return (self.ring, list(self.iterterms())) _hash = None def __hash__(self): # XXX: This computes a hash of a dictionary, but currently we don't # protect dictionary from being changed so any use site modifications # will make hashing go wrong. Use this feature with caution until we # figure out how to make a safe API without compromising speed of this # low-level class. _hash = self._hash if _hash is None: self._hash = _hash = hash((self.ring, frozenset(self.items()))) return _hash def copy(self): """Return a copy of polynomial self. Polynomials are mutable; if one is interested in preserving a polynomial, and one plans to use inplace operations, one can copy the polynomial. This method makes a shallow copy. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.rings import ring >>> R, x, y = ring('x, y', ZZ) >>> p = (x + y)**2 >>> p1 = p.copy() >>> p2 = p >>> p[R.zero_monom] = 3 >>> p x**2 + 2*x*y + y**2 + 3 >>> p1 x**2 + 2*x*y + y**2 >>> p2 x**2 + 2*x*y + y**2 + 3 """ return self.new(self) def set_ring(self, new_ring): if self.ring == new_ring: return self elif self.ring.symbols != new_ring.symbols: terms = list(zip(*_dict_reorder(self, self.ring.symbols, new_ring.symbols))) return new_ring.from_terms(terms) else: return new_ring.from_dict(self) def as_expr(self, *symbols): if symbols and len(symbols) != self.ring.ngens: raise ValueError("not enough symbols, expected %s got %s" % (self.ring.ngens, len(symbols))) else: symbols = self.ring.symbols return expr_from_dict(self.as_expr_dict(), *symbols) def as_expr_dict(self): to_sympy = self.ring.domain.to_sympy return {monom: to_sympy(coeff) for monom, coeff in self.iterterms()} def clear_denoms(self): domain = self.ring.domain if not domain.is_Field or not domain.has_assoc_Ring: return domain.one, self ground_ring = domain.get_ring() common = ground_ring.one lcm = ground_ring.lcm denom = domain.denom for coeff in self.values(): common = lcm(common, denom(coeff)) poly = self.new([ (k, v*common) for k, v in self.items() ]) return common, poly def strip_zero(self): """Eliminate monomials with zero coefficient. """ for k, v in list(self.items()): if not v: del self[k] def __eq__(p1, p2): """Equality test for polynomials. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.rings import ring >>> _, x, y = ring('x, y', ZZ) >>> p1 = (x + y)**2 + (x - y)**2 >>> p1 == 4*x*y False >>> p1 == 2*(x**2 + y**2) True """ if not p2: return not p1 elif isinstance(p2, PolyElement) and p2.ring == p1.ring: return dict.__eq__(p1, p2) elif len(p1) > 1: return False else: return p1.get(p1.ring.zero_monom) == p2 def __ne__(p1, p2): return not p1 == p2 def almosteq(p1, p2, tolerance=None): """Approximate equality test for polynomials. """ ring = p1.ring if isinstance(p2, ring.dtype): if set(p1.keys()) != set(p2.keys()): return False almosteq = ring.domain.almosteq for k in p1.keys(): if not almosteq(p1[k], p2[k], tolerance): return False else: return True elif len(p1) > 1: return False else: try: p2 = ring.domain.convert(p2) except CoercionFailed: return False else: return ring.domain.almosteq(p1.const(), p2, tolerance) def sort_key(self): return (len(self), self.terms()) def _cmp(p1, p2, op): if isinstance(p2, p1.ring.dtype): return op(p1.sort_key(), p2.sort_key()) else: return NotImplemented def __lt__(p1, p2): return p1._cmp(p2, lt) def __le__(p1, p2): return p1._cmp(p2, le) def __gt__(p1, p2): return p1._cmp(p2, gt) def __ge__(p1, p2): return p1._cmp(p2, ge) def _drop(self, gen): ring = self.ring i = ring.index(gen) if ring.ngens == 1: return i, ring.domain else: symbols = list(ring.symbols) del symbols[i] return i, ring.clone(symbols=symbols) def drop(self, gen): i, ring = self._drop(gen) if self.ring.ngens == 1: if self.is_ground: return self.coeff(1) else: raise ValueError("can't drop %s" % gen) else: poly = ring.zero for k, v in self.items(): if k[i] == 0: K = list(k) del K[i] poly[tuple(K)] = v else: raise ValueError("can't drop %s" % gen) return poly def _drop_to_ground(self, gen): ring = self.ring i = ring.index(gen) symbols = list(ring.symbols) del symbols[i] return i, ring.clone(symbols=symbols, domain=ring[i]) def drop_to_ground(self, gen): if self.ring.ngens == 1: raise ValueError("can't drop only generator to ground") i, ring = self._drop_to_ground(gen) poly = ring.zero gen = ring.domain.gens[0] for monom, coeff in self.iterterms(): mon = monom[:i] + monom[i+1:] if not mon in poly: poly[mon] = (gen**monom[i]).mul_ground(coeff) else: poly[mon] += (gen**monom[i]).mul_ground(coeff) return poly def to_dense(self): return dmp_from_dict(self, self.ring.ngens-1, self.ring.domain) def to_dict(self): return dict(self) def str(self, printer, precedence, exp_pattern, mul_symbol): if not self: return printer._print(self.ring.domain.zero) prec_mul = precedence["Mul"] prec_atom = precedence["Atom"] ring = self.ring symbols = ring.symbols ngens = ring.ngens zm = ring.zero_monom sexpvs = [] for expv, coeff in self.terms(): positive = ring.domain.is_positive(coeff) sign = " + " if positive else " - " sexpvs.append(sign) if expv == zm: scoeff = printer._print(coeff) if scoeff.startswith("-"): scoeff = scoeff[1:] else: if not positive: coeff = -coeff if coeff != 1: scoeff = printer.parenthesize(coeff, prec_mul, strict=True) else: scoeff = '' sexpv = [] for i in range(ngens): exp = expv[i] if not exp: continue symbol = printer.parenthesize(symbols[i], prec_atom, strict=True) if exp != 1: if exp != int(exp) or exp < 0: sexp = printer.parenthesize(exp, prec_atom, strict=False) else: sexp = exp sexpv.append(exp_pattern % (symbol, sexp)) else: sexpv.append('%s' % symbol) if scoeff: sexpv = [scoeff] + sexpv sexpvs.append(mul_symbol.join(sexpv)) if sexpvs[0] in [" + ", " - "]: head = sexpvs.pop(0) if head == " - ": sexpvs.insert(0, "-") return "".join(sexpvs) @property def is_generator(self): return self in self.ring._gens_set @property def is_ground(self): return not self or (len(self) == 1 and self.ring.zero_monom in self) @property def is_monomial(self): return not self or (len(self) == 1 and self.LC == 1) @property def is_term(self): return len(self) <= 1 @property def is_negative(self): return self.ring.domain.is_negative(self.LC) @property def is_positive(self): return self.ring.domain.is_positive(self.LC) @property def is_nonnegative(self): return self.ring.domain.is_nonnegative(self.LC) @property def is_nonpositive(self): return self.ring.domain.is_nonpositive(self.LC) @property def is_zero(f): return not f @property def is_one(f): return f == f.ring.one @property def is_monic(f): return f.ring.domain.is_one(f.LC) @property def is_primitive(f): return f.ring.domain.is_one(f.content()) @property def is_linear(f): return all(sum(monom) <= 1 for monom in f.itermonoms()) @property def is_quadratic(f): return all(sum(monom) <= 2 for monom in f.itermonoms()) @property def is_squarefree(f): if not f.ring.ngens: return True return f.ring.dmp_sqf_p(f) @property def is_irreducible(f): if not f.ring.ngens: return True return f.ring.dmp_irreducible_p(f) @property def is_cyclotomic(f): if f.ring.is_univariate: return f.ring.dup_cyclotomic_p(f) else: raise MultivariatePolynomialError("cyclotomic polynomial") def __neg__(self): return self.new([ (monom, -coeff) for monom, coeff in self.iterterms() ]) def __pos__(self): return self def __add__(p1, p2): """Add two polynomials. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.rings import ring >>> _, x, y = ring('x, y', ZZ) >>> (x + y)**2 + (x - y)**2 2*x**2 + 2*y**2 """ if not p2: return p1.copy() ring = p1.ring if isinstance(p2, ring.dtype): p = p1.copy() get = p.get zero = ring.domain.zero for k, v in p2.items(): v = get(k, zero) + v if v: p[k] = v else: del p[k] return p elif isinstance(p2, PolyElement): if isinstance(ring.domain, PolynomialRing) and ring.domain.ring == p2.ring: pass elif isinstance(p2.ring.domain, PolynomialRing) and p2.ring.domain.ring == ring: return p2.__radd__(p1) else: return NotImplemented try: cp2 = ring.domain_new(p2) except CoercionFailed: return NotImplemented else: p = p1.copy() if not cp2: return p zm = ring.zero_monom if zm not in p1.keys(): p[zm] = cp2 else: if p2 == -p[zm]: del p[zm] else: p[zm] += cp2 return p def __radd__(p1, n): p = p1.copy() if not n: return p ring = p1.ring try: n = ring.domain_new(n) except CoercionFailed: return NotImplemented else: zm = ring.zero_monom if zm not in p1.keys(): p[zm] = n else: if n == -p[zm]: del p[zm] else: p[zm] += n return p def __sub__(p1, p2): """Subtract polynomial p2 from p1. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.rings import ring >>> _, x, y = ring('x, y', ZZ) >>> p1 = x + y**2 >>> p2 = x*y + y**2 >>> p1 - p2 -x*y + x """ if not p2: return p1.copy() ring = p1.ring if isinstance(p2, ring.dtype): p = p1.copy() get = p.get zero = ring.domain.zero for k, v in p2.items(): v = get(k, zero) - v if v: p[k] = v else: del p[k] return p elif isinstance(p2, PolyElement): if isinstance(ring.domain, PolynomialRing) and ring.domain.ring == p2.ring: pass elif isinstance(p2.ring.domain, PolynomialRing) and p2.ring.domain.ring == ring: return p2.__rsub__(p1) else: return NotImplemented try: p2 = ring.domain_new(p2) except CoercionFailed: return NotImplemented else: p = p1.copy() zm = ring.zero_monom if zm not in p1.keys(): p[zm] = -p2 else: if p2 == p[zm]: del p[zm] else: p[zm] -= p2 return p def __rsub__(p1, n): """n - p1 with n convertible to the coefficient domain. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.rings import ring >>> _, x, y = ring('x, y', ZZ) >>> p = x + y >>> 4 - p -x - y + 4 """ ring = p1.ring try: n = ring.domain_new(n) except CoercionFailed: return NotImplemented else: p = ring.zero for expv in p1: p[expv] = -p1[expv] p += n return p def __mul__(p1, p2): """Multiply two polynomials. Examples ======== >>> from sympy.polys.domains import QQ >>> from sympy.polys.rings import ring >>> _, x, y = ring('x, y', QQ) >>> p1 = x + y >>> p2 = x - y >>> p1*p2 x**2 - y**2 """ ring = p1.ring p = ring.zero if not p1 or not p2: return p elif isinstance(p2, ring.dtype): get = p.get zero = ring.domain.zero monomial_mul = ring.monomial_mul p2it = list(p2.items()) for exp1, v1 in p1.items(): for exp2, v2 in p2it: exp = monomial_mul(exp1, exp2) p[exp] = get(exp, zero) + v1*v2 p.strip_zero() return p elif isinstance(p2, PolyElement): if isinstance(ring.domain, PolynomialRing) and ring.domain.ring == p2.ring: pass elif isinstance(p2.ring.domain, PolynomialRing) and p2.ring.domain.ring == ring: return p2.__rmul__(p1) else: return NotImplemented try: p2 = ring.domain_new(p2) except CoercionFailed: return NotImplemented else: for exp1, v1 in p1.items(): v = v1*p2 if v: p[exp1] = v return p def __rmul__(p1, p2): """p2 * p1 with p2 in the coefficient domain of p1. Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.rings import ring >>> _, x, y = ring('x, y', ZZ) >>> p = x + y >>> 4 * p 4*x + 4*y """ p = p1.ring.zero if not p2: return p try: p2 = p.ring.domain_new(p2) except CoercionFailed: return NotImplemented else: for exp1, v1 in p1.items(): v = p2*v1 if v: p[exp1] = v return p def __pow__(self, n): """raise polynomial to power `n` Examples ======== >>> from sympy.polys.domains import ZZ >>> from sympy.polys.rings import ring >>> _, x, y = ring('x, y', ZZ) >>> p = x + y**2 >>> p**3 x**3 + 3*x**2*y**2 + 3*x*y**4 + y**6 """ ring = self.ring if not n: if self: return ring.one else: raise ValueError("0**0") elif len(self) == 1: monom, coeff = list(self.items())[0] p = ring.zero if coeff == 1: p[ring.monomial_pow(monom, n)] = coeff else: p[ring.monomial_pow(monom, n)] = coeff**n return p # For ring series, we need negative and rational exponent support only # with monomials. n = int(n) if n < 0: raise ValueError("Negative exponent") elif n == 1: return self.copy() elif n == 2: return self.square() elif n == 3: return self*self.square() elif len(self) <= 5: # TODO: use an actuall density measure return self._pow_multinomial(n) else: return self._pow_generic(n) def _pow_generic(self, n): p = self.ring.one c = self while True: if n & 1: p = p*c n -= 1 if not n: break c = c.square() n = n // 2 return p def _pow_multinomial(self, n): multinomials = list(multinomial_coefficients(len(self), n).items()) monomial_mulpow = self.ring.monomial_mulpow zero_monom = self.ring.zero_monom terms = list(self.iterterms()) zero = self.ring.domain.zero poly = self.ring.zero for multinomial, multinomial_coeff in multinomials: product_monom = zero_monom product_coeff = multinomial_coeff for exp, (monom, coeff) in zip(multinomial, terms): if exp: product_monom = monomial_mulpow(product_monom, monom, exp) product_coeff *= coeff**exp monom = tuple(product_monom) coeff = product_coeff coeff = poly.get(monom, zero) + coeff if coeff: poly[monom] = coeff else: del poly[monom] return poly def square(self): """square of a polynomial Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> _, x, y = ring('x, y', ZZ) >>> p = x + y**2 >>> p.square() x**2 + 2*x*y**2 + y**4 """ ring = self.ring p = ring.zero get = p.get keys = list(self.keys()) zero = ring.domain.zero monomial_mul = ring.monomial_mul for i in range(len(keys)): k1 = keys[i] pk = self[k1] for j in range(i): k2 = keys[j] exp = monomial_mul(k1, k2) p[exp] = get(exp, zero) + pk*self[k2] p = p.imul_num(2) get = p.get for k, v in self.items(): k2 = monomial_mul(k, k) p[k2] = get(k2, zero) + v**2 p.strip_zero() return p def __divmod__(p1, p2): ring = p1.ring if not p2: raise ZeroDivisionError("polynomial division") elif isinstance(p2, ring.dtype): return p1.div(p2) elif isinstance(p2, PolyElement): if isinstance(ring.domain, PolynomialRing) and ring.domain.ring == p2.ring: pass elif isinstance(p2.ring.domain, PolynomialRing) and p2.ring.domain.ring == ring: return p2.__rdivmod__(p1) else: return NotImplemented try: p2 = ring.domain_new(p2) except CoercionFailed: return NotImplemented else: return (p1.quo_ground(p2), p1.rem_ground(p2)) def __rdivmod__(p1, p2): return NotImplemented def __mod__(p1, p2): ring = p1.ring if not p2: raise ZeroDivisionError("polynomial division") elif isinstance(p2, ring.dtype): return p1.rem(p2) elif isinstance(p2, PolyElement): if isinstance(ring.domain, PolynomialRing) and ring.domain.ring == p2.ring: pass elif isinstance(p2.ring.domain, PolynomialRing) and p2.ring.domain.ring == ring: return p2.__rmod__(p1) else: return NotImplemented try: p2 = ring.domain_new(p2) except CoercionFailed: return NotImplemented else: return p1.rem_ground(p2) def __rmod__(p1, p2): return NotImplemented def __truediv__(p1, p2): ring = p1.ring if not p2: raise ZeroDivisionError("polynomial division") elif isinstance(p2, ring.dtype): if p2.is_monomial: return p1*(p2**(-1)) else: return p1.quo(p2) elif isinstance(p2, PolyElement): if isinstance(ring.domain, PolynomialRing) and ring.domain.ring == p2.ring: pass elif isinstance(p2.ring.domain, PolynomialRing) and p2.ring.domain.ring == ring: return p2.__rtruediv__(p1) else: return NotImplemented try: p2 = ring.domain_new(p2) except CoercionFailed: return NotImplemented else: return p1.quo_ground(p2) def __rtruediv__(p1, p2): return NotImplemented __floordiv__ = __div__ = __truediv__ __rfloordiv__ = __rdiv__ = __rtruediv__ # TODO: use // (__floordiv__) for exquo()? def _term_div(self): zm = self.ring.zero_monom domain = self.ring.domain domain_quo = domain.quo monomial_div = self.ring.monomial_div if domain.is_Field: def term_div(a_lm_a_lc, b_lm_b_lc): a_lm, a_lc = a_lm_a_lc b_lm, b_lc = b_lm_b_lc if b_lm == zm: # apparently this is a very common case monom = a_lm else: monom = monomial_div(a_lm, b_lm) if monom is not None: return monom, domain_quo(a_lc, b_lc) else: return None else: def term_div(a_lm_a_lc, b_lm_b_lc): a_lm, a_lc = a_lm_a_lc b_lm, b_lc = b_lm_b_lc if b_lm == zm: # apparently this is a very common case monom = a_lm else: monom = monomial_div(a_lm, b_lm) if not (monom is None or a_lc % b_lc): return monom, domain_quo(a_lc, b_lc) else: return None return term_div def div(self, fv): """Division algorithm, see [CLO] p64. fv array of polynomials return qv, r such that self = sum(fv[i]*qv[i]) + r All polynomials are required not to be Laurent polynomials. Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> _, x, y = ring('x, y', ZZ) >>> f = x**3 >>> f0 = x - y**2 >>> f1 = x - y >>> qv, r = f.div((f0, f1)) >>> qv[0] x**2 + x*y**2 + y**4 >>> qv[1] 0 >>> r y**6 """ ring = self.ring ret_single = False if isinstance(fv, PolyElement): ret_single = True fv = [fv] if any(not f for f in fv): raise ZeroDivisionError("polynomial division") if not self: if ret_single: return ring.zero, ring.zero else: return [], ring.zero for f in fv: if f.ring != ring: raise ValueError('self and f must have the same ring') s = len(fv) qv = [ring.zero for i in range(s)] p = self.copy() r = ring.zero term_div = self._term_div() expvs = [fx.leading_expv() for fx in fv] while p: i = 0 divoccurred = 0 while i < s and divoccurred == 0: expv = p.leading_expv() term = term_div((expv, p[expv]), (expvs[i], fv[i][expvs[i]])) if term is not None: expv1, c = term qv[i] = qv[i]._iadd_monom((expv1, c)) p = p._iadd_poly_monom(fv[i], (expv1, -c)) divoccurred = 1 else: i += 1 if not divoccurred: expv = p.leading_expv() r = r._iadd_monom((expv, p[expv])) del p[expv] if expv == ring.zero_monom: r += p if ret_single: if not qv: return ring.zero, r else: return qv[0], r else: return qv, r def rem(self, G): f = self if isinstance(G, PolyElement): G = [G] if any(not g for g in G): raise ZeroDivisionError("polynomial division") ring = f.ring domain = ring.domain zero = domain.zero monomial_mul = ring.monomial_mul r = ring.zero term_div = f._term_div() ltf = f.LT f = f.copy() get = f.get while f: for g in G: tq = term_div(ltf, g.LT) if tq is not None: m, c = tq for mg, cg in g.iterterms(): m1 = monomial_mul(mg, m) c1 = get(m1, zero) - c*cg if not c1: del f[m1] else: f[m1] = c1 ltm = f.leading_expv() if ltm is not None: ltf = ltm, f[ltm] break else: ltm, ltc = ltf if ltm in r: r[ltm] += ltc else: r[ltm] = ltc del f[ltm] ltm = f.leading_expv() if ltm is not None: ltf = ltm, f[ltm] return r def quo(f, G): return f.div(G)[0] def exquo(f, G): q, r = f.div(G) if not r: return q else: raise ExactQuotientFailed(f, G) def _iadd_monom(self, mc): """add to self the monomial coeff*x0**i0*x1**i1*... unless self is a generator -- then just return the sum of the two. mc is a tuple, (monom, coeff), where monomial is (i0, i1, ...) Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> _, x, y = ring('x, y', ZZ) >>> p = x**4 + 2*y >>> m = (1, 2) >>> p1 = p._iadd_monom((m, 5)) >>> p1 x**4 + 5*x*y**2 + 2*y >>> p1 is p True >>> p = x >>> p1 = p._iadd_monom((m, 5)) >>> p1 5*x*y**2 + x >>> p1 is p False """ if self in self.ring._gens_set: cpself = self.copy() else: cpself = self expv, coeff = mc c = cpself.get(expv) if c is None: cpself[expv] = coeff else: c += coeff if c: cpself[expv] = c else: del cpself[expv] return cpself def _iadd_poly_monom(self, p2, mc): """add to self the product of (p)*(coeff*x0**i0*x1**i1*...) unless self is a generator -- then just return the sum of the two. mc is a tuple, (monom, coeff), where monomial is (i0, i1, ...) Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> _, x, y, z = ring('x, y, z', ZZ) >>> p1 = x**4 + 2*y >>> p2 = y + z >>> m = (1, 2, 3) >>> p1 = p1._iadd_poly_monom(p2, (m, 3)) >>> p1 x**4 + 3*x*y**3*z**3 + 3*x*y**2*z**4 + 2*y """ p1 = self if p1 in p1.ring._gens_set: p1 = p1.copy() (m, c) = mc get = p1.get zero = p1.ring.domain.zero monomial_mul = p1.ring.monomial_mul for k, v in p2.items(): ka = monomial_mul(k, m) coeff = get(ka, zero) + v*c if coeff: p1[ka] = coeff else: del p1[ka] return p1 def degree(f, x=None): """ The leading degree in ``x`` or the main variable. Note that the degree of 0 is negative infinity (the SymPy object -oo). """ i = f.ring.index(x) if not f: return -oo elif i < 0: return 0 else: return max([ monom[i] for monom in f.itermonoms() ]) def degrees(f): """ A tuple containing leading degrees in all variables. Note that the degree of 0 is negative infinity (the SymPy object -oo) """ if not f: return (-oo,)*f.ring.ngens else: return tuple(map(max, list(zip(*f.itermonoms())))) def tail_degree(f, x=None): """ The tail degree in ``x`` or the main variable. Note that the degree of 0 is negative infinity (the SymPy object -oo) """ i = f.ring.index(x) if not f: return -oo elif i < 0: return 0 else: return min([ monom[i] for monom in f.itermonoms() ]) def tail_degrees(f): """ A tuple containing tail degrees in all variables. Note that the degree of 0 is negative infinity (the SymPy object -oo) """ if not f: return (-oo,)*f.ring.ngens else: return tuple(map(min, list(zip(*f.itermonoms())))) def leading_expv(self): """Leading monomial tuple according to the monomial ordering. Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> _, x, y, z = ring('x, y, z', ZZ) >>> p = x**4 + x**3*y + x**2*z**2 + z**7 >>> p.leading_expv() (4, 0, 0) """ if self: return self.ring.leading_expv(self) else: return None def _get_coeff(self, expv): return self.get(expv, self.ring.domain.zero) def coeff(self, element): """ Returns the coefficient that stands next to the given monomial. Parameters ========== element : PolyElement (with ``is_monomial = True``) or 1 Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> _, x, y, z = ring("x,y,z", ZZ) >>> f = 3*x**2*y - x*y*z + 7*z**3 + 23 >>> f.coeff(x**2*y) 3 >>> f.coeff(x*y) 0 >>> f.coeff(1) 23 """ if element == 1: return self._get_coeff(self.ring.zero_monom) elif isinstance(element, self.ring.dtype): terms = list(element.iterterms()) if len(terms) == 1: monom, coeff = terms[0] if coeff == self.ring.domain.one: return self._get_coeff(monom) raise ValueError("expected a monomial, got %s" % element) def const(self): """Returns the constant coeffcient. """ return self._get_coeff(self.ring.zero_monom) @property def LC(self): return self._get_coeff(self.leading_expv()) @property def LM(self): expv = self.leading_expv() if expv is None: return self.ring.zero_monom else: return expv def leading_monom(self): """ Leading monomial as a polynomial element. Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> _, x, y = ring('x, y', ZZ) >>> (3*x*y + y**2).leading_monom() x*y """ p = self.ring.zero expv = self.leading_expv() if expv: p[expv] = self.ring.domain.one return p @property def LT(self): expv = self.leading_expv() if expv is None: return (self.ring.zero_monom, self.ring.domain.zero) else: return (expv, self._get_coeff(expv)) def leading_term(self): """Leading term as a polynomial element. Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> _, x, y = ring('x, y', ZZ) >>> (3*x*y + y**2).leading_term() 3*x*y """ p = self.ring.zero expv = self.leading_expv() if expv is not None: p[expv] = self[expv] return p def _sorted(self, seq, order): if order is None: order = self.ring.order else: order = OrderOpt.preprocess(order) if order is lex: return sorted(seq, key=lambda monom: monom[0], reverse=True) else: return sorted(seq, key=lambda monom: order(monom[0]), reverse=True) def coeffs(self, order=None): """Ordered list of polynomial coefficients. Parameters ========== order : :class:`Order` or coercible, optional Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> from sympy.polys.orderings import lex, grlex >>> _, x, y = ring("x, y", ZZ, lex) >>> f = x*y**7 + 2*x**2*y**3 >>> f.coeffs() [2, 1] >>> f.coeffs(grlex) [1, 2] """ return [ coeff for _, coeff in self.terms(order) ] def monoms(self, order=None): """Ordered list of polynomial monomials. Parameters ========== order : :class:`Order` or coercible, optional Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> from sympy.polys.orderings import lex, grlex >>> _, x, y = ring("x, y", ZZ, lex) >>> f = x*y**7 + 2*x**2*y**3 >>> f.monoms() [(2, 3), (1, 7)] >>> f.monoms(grlex) [(1, 7), (2, 3)] """ return [ monom for monom, _ in self.terms(order) ] def terms(self, order=None): """Ordered list of polynomial terms. Parameters ========== order : :class:`Order` or coercible, optional Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> from sympy.polys.orderings import lex, grlex >>> _, x, y = ring("x, y", ZZ, lex) >>> f = x*y**7 + 2*x**2*y**3 >>> f.terms() [((2, 3), 2), ((1, 7), 1)] >>> f.terms(grlex) [((1, 7), 1), ((2, 3), 2)] """ return self._sorted(list(self.items()), order) def itercoeffs(self): """Iterator over coefficients of a polynomial. """ return iter(self.values()) def itermonoms(self): """Iterator over monomials of a polynomial. """ return iter(self.keys()) def iterterms(self): """Iterator over terms of a polynomial. """ return iter(self.items()) def listcoeffs(self): """Unordered list of polynomial coefficients. """ return list(self.values()) def listmonoms(self): """Unordered list of polynomial monomials. """ return list(self.keys()) def listterms(self): """Unordered list of polynomial terms. """ return list(self.items()) def imul_num(p, c): """multiply inplace the polynomial p by an element in the coefficient ring, provided p is not one of the generators; else multiply not inplace Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> _, x, y = ring('x, y', ZZ) >>> p = x + y**2 >>> p1 = p.imul_num(3) >>> p1 3*x + 3*y**2 >>> p1 is p True >>> p = x >>> p1 = p.imul_num(3) >>> p1 3*x >>> p1 is p False """ if p in p.ring._gens_set: return p*c if not c: p.clear() return for exp in p: p[exp] *= c return p def content(f): """Returns GCD of polynomial's coefficients. """ domain = f.ring.domain cont = domain.zero gcd = domain.gcd for coeff in f.itercoeffs(): cont = gcd(cont, coeff) return cont def primitive(f): """Returns content and a primitive polynomial. """ cont = f.content() return cont, f.quo_ground(cont) def monic(f): """Divides all coefficients by the leading coefficient. """ if not f: return f else: return f.quo_ground(f.LC) def mul_ground(f, x): if not x: return f.ring.zero terms = [ (monom, coeff*x) for monom, coeff in f.iterterms() ] return f.new(terms) def mul_monom(f, monom): monomial_mul = f.ring.monomial_mul terms = [ (monomial_mul(f_monom, monom), f_coeff) for f_monom, f_coeff in f.items() ] return f.new(terms) def mul_term(f, term): monom, coeff = term if not f or not coeff: return f.ring.zero elif monom == f.ring.zero_monom: return f.mul_ground(coeff) monomial_mul = f.ring.monomial_mul terms = [ (monomial_mul(f_monom, monom), f_coeff*coeff) for f_monom, f_coeff in f.items() ] return f.new(terms) def quo_ground(f, x): domain = f.ring.domain if not x: raise ZeroDivisionError('polynomial division') if not f or x == domain.one: return f if domain.is_Field: quo = domain.quo terms = [ (monom, quo(coeff, x)) for monom, coeff in f.iterterms() ] else: terms = [ (monom, coeff // x) for monom, coeff in f.iterterms() if not (coeff % x) ] return f.new(terms) def quo_term(f, term): monom, coeff = term if not coeff: raise ZeroDivisionError("polynomial division") elif not f: return f.ring.zero elif monom == f.ring.zero_monom: return f.quo_ground(coeff) term_div = f._term_div() terms = [ term_div(t, term) for t in f.iterterms() ] return f.new([ t for t in terms if t is not None ]) def trunc_ground(f, p): if f.ring.domain.is_ZZ: terms = [] for monom, coeff in f.iterterms(): coeff = coeff % p if coeff > p // 2: coeff = coeff - p terms.append((monom, coeff)) else: terms = [ (monom, coeff % p) for monom, coeff in f.iterterms() ] poly = f.new(terms) poly.strip_zero() return poly rem_ground = trunc_ground def extract_ground(self, g): f = self fc = f.content() gc = g.content() gcd = f.ring.domain.gcd(fc, gc) f = f.quo_ground(gcd) g = g.quo_ground(gcd) return gcd, f, g def _norm(f, norm_func): if not f: return f.ring.domain.zero else: ground_abs = f.ring.domain.abs return norm_func([ ground_abs(coeff) for coeff in f.itercoeffs() ]) def max_norm(f): return f._norm(max) def l1_norm(f): return f._norm(sum) def deflate(f, *G): ring = f.ring polys = [f] + list(G) J = [0]*ring.ngens for p in polys: for monom in p.itermonoms(): for i, m in enumerate(monom): J[i] = igcd(J[i], m) for i, b in enumerate(J): if not b: J[i] = 1 J = tuple(J) if all(b == 1 for b in J): return J, polys H = [] for p in polys: h = ring.zero for I, coeff in p.iterterms(): N = [ i // j for i, j in zip(I, J) ] h[tuple(N)] = coeff H.append(h) return J, H def inflate(f, J): poly = f.ring.zero for I, coeff in f.iterterms(): N = [ i*j for i, j in zip(I, J) ] poly[tuple(N)] = coeff return poly def lcm(self, g): f = self domain = f.ring.domain if not domain.is_Field: fc, f = f.primitive() gc, g = g.primitive() c = domain.lcm(fc, gc) h = (f*g).quo(f.gcd(g)) if not domain.is_Field: return h.mul_ground(c) else: return h.monic() def gcd(f, g): return f.cofactors(g)[0] def cofactors(f, g): if not f and not g: zero = f.ring.zero return zero, zero, zero elif not f: h, cff, cfg = f._gcd_zero(g) return h, cff, cfg elif not g: h, cfg, cff = g._gcd_zero(f) return h, cff, cfg elif len(f) == 1: h, cff, cfg = f._gcd_monom(g) return h, cff, cfg elif len(g) == 1: h, cfg, cff = g._gcd_monom(f) return h, cff, cfg J, (f, g) = f.deflate(g) h, cff, cfg = f._gcd(g) return (h.inflate(J), cff.inflate(J), cfg.inflate(J)) def _gcd_zero(f, g): one, zero = f.ring.one, f.ring.zero if g.is_nonnegative: return g, zero, one else: return -g, zero, -one def _gcd_monom(f, g): ring = f.ring ground_gcd = ring.domain.gcd ground_quo = ring.domain.quo monomial_gcd = ring.monomial_gcd monomial_ldiv = ring.monomial_ldiv mf, cf = list(f.iterterms())[0] _mgcd, _cgcd = mf, cf for mg, cg in g.iterterms(): _mgcd = monomial_gcd(_mgcd, mg) _cgcd = ground_gcd(_cgcd, cg) h = f.new([(_mgcd, _cgcd)]) cff = f.new([(monomial_ldiv(mf, _mgcd), ground_quo(cf, _cgcd))]) cfg = f.new([(monomial_ldiv(mg, _mgcd), ground_quo(cg, _cgcd)) for mg, cg in g.iterterms()]) return h, cff, cfg def _gcd(f, g): ring = f.ring if ring.domain.is_QQ: return f._gcd_QQ(g) elif ring.domain.is_ZZ: return f._gcd_ZZ(g) else: # TODO: don't use dense representation (port PRS algorithms) return ring.dmp_inner_gcd(f, g) def _gcd_ZZ(f, g): return heugcd(f, g) def _gcd_QQ(self, g): f = self ring = f.ring new_ring = ring.clone(domain=ring.domain.get_ring()) cf, f = f.clear_denoms() cg, g = g.clear_denoms() f = f.set_ring(new_ring) g = g.set_ring(new_ring) h, cff, cfg = f._gcd_ZZ(g) h = h.set_ring(ring) c, h = h.LC, h.monic() cff = cff.set_ring(ring).mul_ground(ring.domain.quo(c, cf)) cfg = cfg.set_ring(ring).mul_ground(ring.domain.quo(c, cg)) return h, cff, cfg def cancel(self, g): """ Cancel common factors in a rational function ``f/g``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> (2*x**2 - 2).cancel(x**2 - 2*x + 1) (2*x + 2, x - 1) """ f = self ring = f.ring if not f: return f, ring.one domain = ring.domain if not (domain.is_Field and domain.has_assoc_Ring): _, p, q = f.cofactors(g) if q.is_negative: p, q = -p, -q else: new_ring = ring.clone(domain=domain.get_ring()) cq, f = f.clear_denoms() cp, g = g.clear_denoms() f = f.set_ring(new_ring) g = g.set_ring(new_ring) _, p, q = f.cofactors(g) _, cp, cq = new_ring.domain.cofactors(cp, cq) p = p.set_ring(ring) q = q.set_ring(ring) p_neg = p.is_negative q_neg = q.is_negative if p_neg and q_neg: p, q = -p, -q elif p_neg: cp, p = -cp, -p elif q_neg: cp, q = -cp, -q p = p.mul_ground(cp) q = q.mul_ground(cq) return p, q def diff(f, x): """Computes partial derivative in ``x``. Examples ======== >>> from sympy.polys.rings import ring >>> from sympy.polys.domains import ZZ >>> _, x, y = ring("x,y", ZZ) >>> p = x + x**2*y**3 >>> p.diff(x) 2*x*y**3 + 1 """ ring = f.ring i = ring.index(x) m = ring.monomial_basis(i) g = ring.zero for expv, coeff in f.iterterms(): if expv[i]: e = ring.monomial_ldiv(expv, m) g[e] = ring.domain_new(coeff*expv[i]) return g def __call__(f, *values): if 0 < len(values) <= f.ring.ngens: return f.evaluate(list(zip(f.ring.gens, values))) else: raise ValueError("expected at least 1 and at most %s values, got %s" % (f.ring.ngens, len(values))) def evaluate(self, x, a=None): f = self if isinstance(x, list) and a is None: (X, a), x = x[0], x[1:] f = f.evaluate(X, a) if not x: return f else: x = [ (Y.drop(X), a) for (Y, a) in x ] return f.evaluate(x) ring = f.ring i = ring.index(x) a = ring.domain.convert(a) if ring.ngens == 1: result = ring.domain.zero for (n,), coeff in f.iterterms(): result += coeff*a**n return result else: poly = ring.drop(x).zero for monom, coeff in f.iterterms(): n, monom = monom[i], monom[:i] + monom[i+1:] coeff = coeff*a**n if monom in poly: coeff = coeff + poly[monom] if coeff: poly[monom] = coeff else: del poly[monom] else: if coeff: poly[monom] = coeff return poly def subs(self, x, a=None): f = self if isinstance(x, list) and a is None: for X, a in x: f = f.subs(X, a) return f ring = f.ring i = ring.index(x) a = ring.domain.convert(a) if ring.ngens == 1: result = ring.domain.zero for (n,), coeff in f.iterterms(): result += coeff*a**n return ring.ground_new(result) else: poly = ring.zero for monom, coeff in f.iterterms(): n, monom = monom[i], monom[:i] + (0,) + monom[i+1:] coeff = coeff*a**n if monom in poly: coeff = coeff + poly[monom] if coeff: poly[monom] = coeff else: del poly[monom] else: if coeff: poly[monom] = coeff return poly def compose(f, x, a=None): ring = f.ring poly = ring.zero gens_map = dict(list(zip(ring.gens, list(range(ring.ngens))))) if a is not None: replacements = [(x, a)] else: if isinstance(x, list): replacements = list(x) elif isinstance(x, dict): replacements = sorted(list(x.items()), key=lambda k: gens_map[k[0]]) else: raise ValueError("expected a generator, value pair a sequence of such pairs") for k, (x, g) in enumerate(replacements): replacements[k] = (gens_map[x], ring.ring_new(g)) for monom, coeff in f.iterterms(): monom = list(monom) subpoly = ring.one for i, g in replacements: n, monom[i] = monom[i], 0 if n: subpoly *= g**n subpoly = subpoly.mul_term((tuple(monom), coeff)) poly += subpoly return poly # TODO: following methods should point to polynomial # representation independent algorithm implementations. def pdiv(f, g): return f.ring.dmp_pdiv(f, g) def prem(f, g): return f.ring.dmp_prem(f, g) def pquo(f, g): return f.ring.dmp_quo(f, g) def pexquo(f, g): return f.ring.dmp_exquo(f, g) def half_gcdex(f, g): return f.ring.dmp_half_gcdex(f, g) def gcdex(f, g): return f.ring.dmp_gcdex(f, g) def subresultants(f, g): return f.ring.dmp_subresultants(f, g) def resultant(f, g): return f.ring.dmp_resultant(f, g) def discriminant(f): return f.ring.dmp_discriminant(f) def decompose(f): if f.ring.is_univariate: return f.ring.dup_decompose(f) else: raise MultivariatePolynomialError("polynomial decomposition") def shift(f, a): if f.ring.is_univariate: return f.ring.dup_shift(f, a) else: raise MultivariatePolynomialError("polynomial shift") def sturm(f): if f.ring.is_univariate: return f.ring.dup_sturm(f) else: raise MultivariatePolynomialError("sturm sequence") def gff_list(f): return f.ring.dmp_gff_list(f) def sqf_norm(f): return f.ring.dmp_sqf_norm(f) def sqf_part(f): return f.ring.dmp_sqf_part(f) def sqf_list(f, all=False): return f.ring.dmp_sqf_list(f, all=all) def factor_list(f): return f.ring.dmp_factor_list(f)

befa609b3b9e212879e14202cdcba1299674312e31f63263d318e1eaf399663b

"""Options manager for :class:`Poly` and public API functions. """ from __future__ import print_function, division __all__ = ["Options"] from sympy.core import S, Basic, sympify from sympy.core.compatibility import string_types, with_metaclass from sympy.polys.polyerrors import GeneratorsError, OptionError, FlagError from sympy.utilities import numbered_symbols, topological_sort, public from sympy.utilities.iterables import has_dups import sympy.polys import re class Option(object): """Base class for all kinds of options. """ option = None is_Flag = False requires = [] excludes = [] after = [] before = [] @classmethod def default(cls): return None @classmethod def preprocess(cls, option): return None @classmethod def postprocess(cls, options): pass class Flag(Option): """Base class for all kinds of flags. """ is_Flag = True class BooleanOption(Option): """An option that must have a boolean value or equivalent assigned. """ @classmethod def preprocess(cls, value): if value in [True, False]: return bool(value) else: raise OptionError("'%s' must have a boolean value assigned, got %s" % (cls.option, value)) class OptionType(type): """Base type for all options that does registers options. """ def __init__(cls, *args, **kwargs): @property def getter(self): try: return self[cls.option] except KeyError: return cls.default() setattr(Options, cls.option, getter) Options.__options__[cls.option] = cls @public class Options(dict): """ Options manager for polynomial manipulation module. Examples ======== >>> from sympy.polys.polyoptions import Options >>> from sympy.polys.polyoptions import build_options >>> from sympy.abc import x, y, z >>> Options((x, y, z), {'domain': 'ZZ'}) {'auto': False, 'domain': ZZ, 'gens': (x, y, z)} >>> build_options((x, y, z), {'domain': 'ZZ'}) {'auto': False, 'domain': ZZ, 'gens': (x, y, z)} **Options** * Expand --- boolean option * Gens --- option * Wrt --- option * Sort --- option * Order --- option * Field --- boolean option * Greedy --- boolean option * Domain --- option * Split --- boolean option * Gaussian --- boolean option * Extension --- option * Modulus --- option * Symmetric --- boolean option * Strict --- boolean option **Flags** * Auto --- boolean flag * Frac --- boolean flag * Formal --- boolean flag * Polys --- boolean flag * Include --- boolean flag * All --- boolean flag * Gen --- flag * Series --- boolean flag """ __order__ = None __options__ = {} def __init__(self, gens, args, flags=None, strict=False): dict.__init__(self) if gens and args.get('gens', ()): raise OptionError( "both '*gens' and keyword argument 'gens' supplied") elif gens: args = dict(args) args['gens'] = gens defaults = args.pop('defaults', {}) def preprocess_options(args): for option, value in args.items(): try: cls = self.__options__[option] except KeyError: raise OptionError("'%s' is not a valid option" % option) if issubclass(cls, Flag): if flags is None or option not in flags: if strict: raise OptionError("'%s' flag is not allowed in this context" % option) if value is not None: self[option] = cls.preprocess(value) preprocess_options(args) for key, value in dict(defaults).items(): if key in self: del defaults[key] else: for option in self.keys(): cls = self.__options__[option] if key in cls.excludes: del defaults[key] break preprocess_options(defaults) for option in self.keys(): cls = self.__options__[option] for require_option in cls.requires: if self.get(require_option) is None: raise OptionError("'%s' option is only allowed together with '%s'" % (option, require_option)) for exclude_option in cls.excludes: if self.get(exclude_option) is not None: raise OptionError("'%s' option is not allowed together with '%s'" % (option, exclude_option)) for option in self.__order__: self.__options__[option].postprocess(self) @classmethod def _init_dependencies_order(cls): """Resolve the order of options' processing. """ if cls.__order__ is None: vertices, edges = [], set([]) for name, option in cls.__options__.items(): vertices.append(name) for _name in option.after: edges.add((_name, name)) for _name in option.before: edges.add((name, _name)) try: cls.__order__ = topological_sort((vertices, list(edges))) except ValueError: raise RuntimeError( "cycle detected in sympy.polys options framework") def clone(self, updates={}): """Clone ``self`` and update specified options. """ obj = dict.__new__(self.__class__) for option, value in self.items(): obj[option] = value for option, value in updates.items(): obj[option] = value return obj def __setattr__(self, attr, value): if attr in self.__options__: self[attr] = value else: super(Options, self).__setattr__(attr, value) @property def args(self): args = {} for option, value in self.items(): if value is not None and option != 'gens': cls = self.__options__[option] if not issubclass(cls, Flag): args[option] = value return args @property def options(self): options = {} for option, cls in self.__options__.items(): if not issubclass(cls, Flag): options[option] = getattr(self, option) return options @property def flags(self): flags = {} for option, cls in self.__options__.items(): if issubclass(cls, Flag): flags[option] = getattr(self, option) return flags class Expand(with_metaclass(OptionType, BooleanOption)): """``expand`` option to polynomial manipulation functions. """ option = 'expand' requires = [] excludes = [] @classmethod def default(cls): return True class Gens(with_metaclass(OptionType, Option)): """``gens`` option to polynomial manipulation functions. """ option = 'gens' requires = [] excludes = [] @classmethod def default(cls): return () @classmethod def preprocess(cls, gens): if isinstance(gens, Basic): gens = (gens,) elif len(gens) == 1 and hasattr(gens[0], '__iter__'): gens = gens[0] if gens == (None,): gens = () elif has_dups(gens): raise GeneratorsError("duplicated generators: %s" % str(gens)) elif any(gen.is_commutative is False for gen in gens): raise GeneratorsError("non-commutative generators: %s" % str(gens)) return tuple(gens) class Wrt(with_metaclass(OptionType, Option)): """``wrt`` option to polynomial manipulation functions. """ option = 'wrt' requires = [] excludes = [] _re_split = re.compile(r"\s*,\s*|\s+") @classmethod def preprocess(cls, wrt): if isinstance(wrt, Basic): return [str(wrt)] elif isinstance(wrt, str): wrt = wrt.strip() if wrt.endswith(','): raise OptionError('Bad input: missing parameter.') if not wrt: return [] return [ gen for gen in cls._re_split.split(wrt) ] elif hasattr(wrt, '__getitem__'): return list(map(str, wrt)) else: raise OptionError("invalid argument for 'wrt' option") class Sort(with_metaclass(OptionType, Option)): """``sort`` option to polynomial manipulation functions. """ option = 'sort' requires = [] excludes = [] @classmethod def default(cls): return [] @classmethod def preprocess(cls, sort): if isinstance(sort, str): return [ gen.strip() for gen in sort.split('>') ] elif hasattr(sort, '__getitem__'): return list(map(str, sort)) else: raise OptionError("invalid argument for 'sort' option") class Order(with_metaclass(OptionType, Option)): """``order`` option to polynomial manipulation functions. """ option = 'order' requires = [] excludes = [] @classmethod def default(cls): return sympy.polys.orderings.lex @classmethod def preprocess(cls, order): return sympy.polys.orderings.monomial_key(order) class Field(with_metaclass(OptionType, BooleanOption)): """``field`` option to polynomial manipulation functions. """ option = 'field' requires = [] excludes = ['domain', 'split', 'gaussian'] class Greedy(with_metaclass(OptionType, BooleanOption)): """``greedy`` option to polynomial manipulation functions. """ option = 'greedy' requires = [] excludes = ['domain', 'split', 'gaussian', 'extension', 'modulus', 'symmetric'] class Composite(with_metaclass(OptionType, BooleanOption)): """``composite`` option to polynomial manipulation functions. """ option = 'composite' @classmethod def default(cls): return None requires = [] excludes = ['domain', 'split', 'gaussian', 'extension', 'modulus', 'symmetric'] class Domain(with_metaclass(OptionType, Option)): """``domain`` option to polynomial manipulation functions. """ option = 'domain' requires = [] excludes = ['field', 'greedy', 'split', 'gaussian', 'extension'] after = ['gens'] _re_realfield = re.compile(r"^(R|RR)(_(\d+))?$") _re_complexfield = re.compile(r"^(C|CC)(_(\d+))?$") _re_finitefield = re.compile(r"^(FF|GF)$(\d+)$$") _re_polynomial = re.compile(r"^(Z|ZZ|Q|QQ)\[(.+)\]$") _re_fraction = re.compile(r"^(Z|ZZ|Q|QQ)$(.+)$$") _re_algebraic = re.compile(r"^(Q|QQ)\<(.+)\>$") @classmethod def preprocess(cls, domain): if isinstance(domain, sympy.polys.domains.Domain): return domain elif hasattr(domain, 'to_domain'): return domain.to_domain() elif isinstance(domain, string_types): if domain in ['Z', 'ZZ']: return sympy.polys.domains.ZZ if domain in ['Q', 'QQ']: return sympy.polys.domains.QQ if domain == 'EX': return sympy.polys.domains.EX r = cls._re_realfield.match(domain) if r is not None: _, _, prec = r.groups() if prec is None: return sympy.polys.domains.RR else: return sympy.polys.domains.RealField(int(prec)) r = cls._re_complexfield.match(domain) if r is not None: _, _, prec = r.groups() if prec is None: return sympy.polys.domains.CC else: return sympy.polys.domains.ComplexField(int(prec)) r = cls._re_finitefield.match(domain) if r is not None: return sympy.polys.domains.FF(int(r.groups()[1])) r = cls._re_polynomial.match(domain) if r is not None: ground, gens = r.groups() gens = list(map(sympify, gens.split(','))) if ground in ['Z', 'ZZ']: return sympy.polys.domains.ZZ.poly_ring(*gens) else: return sympy.polys.domains.QQ.poly_ring(*gens) r = cls._re_fraction.match(domain) if r is not None: ground, gens = r.groups() gens = list(map(sympify, gens.split(','))) if ground in ['Z', 'ZZ']: return sympy.polys.domains.ZZ.frac_field(*gens) else: return sympy.polys.domains.QQ.frac_field(*gens) r = cls._re_algebraic.match(domain) if r is not None: gens = list(map(sympify, r.groups()[1].split(','))) return sympy.polys.domains.QQ.algebraic_field(*gens) raise OptionError('expected a valid domain specification, got %s' % domain) @classmethod def postprocess(cls, options): if 'gens' in options and 'domain' in options and options['domain'].is_Composite and \ (set(options['domain'].symbols) & set(options['gens'])): raise GeneratorsError( "ground domain and generators interfere together") elif ('gens' not in options or not options['gens']) and \ 'domain' in options and options['domain'] == sympy.polys.domains.EX: raise GeneratorsError("you have to provide generators because EX domain was requested") class Split(with_metaclass(OptionType, BooleanOption)): """``split`` option to polynomial manipulation functions. """ option = 'split' requires = [] excludes = ['field', 'greedy', 'domain', 'gaussian', 'extension', 'modulus', 'symmetric'] @classmethod def postprocess(cls, options): if 'split' in options: raise NotImplementedError("'split' option is not implemented yet") class Gaussian(with_metaclass(OptionType, BooleanOption)): """``gaussian`` option to polynomial manipulation functions. """ option = 'gaussian' requires = [] excludes = ['field', 'greedy', 'domain', 'split', 'extension', 'modulus', 'symmetric'] @classmethod def postprocess(cls, options): if 'gaussian' in options and options['gaussian'] is True: options['extension'] = set([S.ImaginaryUnit]) Extension.postprocess(options) class Extension(with_metaclass(OptionType, Option)): """``extension`` option to polynomial manipulation functions. """ option = 'extension' requires = [] excludes = ['greedy', 'domain', 'split', 'gaussian', 'modulus', 'symmetric'] @classmethod def preprocess(cls, extension): if extension == 1: return bool(extension) elif extension == 0: raise OptionError("'False' is an invalid argument for 'extension'") else: if not hasattr(extension, '__iter__'): extension = set([extension]) else: if not extension: extension = None else: extension = set(extension) return extension @classmethod def postprocess(cls, options): if 'extension' in options and options['extension'] is not True: options['domain'] = sympy.polys.domains.QQ.algebraic_field( *options['extension']) class Modulus(with_metaclass(OptionType, Option)): """``modulus`` option to polynomial manipulation functions. """ option = 'modulus' requires = [] excludes = ['greedy', 'split', 'domain', 'gaussian', 'extension'] @classmethod def preprocess(cls, modulus): modulus = sympify(modulus) if modulus.is_Integer and modulus > 0: return int(modulus) else: raise OptionError( "'modulus' must a positive integer, got %s" % modulus) @classmethod def postprocess(cls, options): if 'modulus' in options: modulus = options['modulus'] symmetric = options.get('symmetric', True) options['domain'] = sympy.polys.domains.FF(modulus, symmetric) class Symmetric(with_metaclass(OptionType, BooleanOption)): """``symmetric`` option to polynomial manipulation functions. """ option = 'symmetric' requires = ['modulus'] excludes = ['greedy', 'domain', 'split', 'gaussian', 'extension'] class Strict(with_metaclass(OptionType, BooleanOption)): """``strict`` option to polynomial manipulation functions. """ option = 'strict' @classmethod def default(cls): return True class Auto(with_metaclass(OptionType, BooleanOption, Flag)): """``auto`` flag to polynomial manipulation functions. """ option = 'auto' after = ['field', 'domain', 'extension', 'gaussian'] @classmethod def default(cls): return True @classmethod def postprocess(cls, options): if ('domain' in options or 'field' in options) and 'auto' not in options: options['auto'] = False class Frac(with_metaclass(OptionType, BooleanOption, Flag)): """``auto`` option to polynomial manipulation functions. """ option = 'frac' @classmethod def default(cls): return False class Formal(with_metaclass(OptionType, BooleanOption, Flag)): """``formal`` flag to polynomial manipulation functions. """ option = 'formal' @classmethod def default(cls): return False class Polys(with_metaclass(OptionType, BooleanOption, Flag)): """``polys`` flag to polynomial manipulation functions. """ option = 'polys' class Include(with_metaclass(OptionType, BooleanOption, Flag)): """``include`` flag to polynomial manipulation functions. """ option = 'include' @classmethod def default(cls): return False class All(with_metaclass(OptionType, BooleanOption, Flag)): """``all`` flag to polynomial manipulation functions. """ option = 'all' @classmethod def default(cls): return False class Gen(with_metaclass(OptionType, Flag)): """``gen`` flag to polynomial manipulation functions. """ option = 'gen' @classmethod def default(cls): return 0 @classmethod def preprocess(cls, gen): if isinstance(gen, (Basic, int)): return gen else: raise OptionError("invalid argument for 'gen' option") class Series(with_metaclass(OptionType, BooleanOption, Flag)): """``series`` flag to polynomial manipulation functions. """ option = 'series' @classmethod def default(cls): return False class Symbols(with_metaclass(OptionType, Flag)): """``symbols`` flag to polynomial manipulation functions. """ option = 'symbols' @classmethod def default(cls): return numbered_symbols('s', start=1) @classmethod def preprocess(cls, symbols): if hasattr(symbols, '__iter__'): return iter(symbols) else: raise OptionError("expected an iterator or iterable container, got %s" % symbols) class Method(with_metaclass(OptionType, Flag)): """``method`` flag to polynomial manipulation functions. """ option = 'method' @classmethod def preprocess(cls, method): if isinstance(method, str): return method.lower() else: raise OptionError("expected a string, got %s" % method) def build_options(gens, args=None): """Construct options from keyword arguments or ... options. """ if args is None: gens, args = (), gens if len(args) != 1 or 'opt' not in args or gens: return Options(gens, args) else: return args['opt'] def allowed_flags(args, flags): """ Allow specified flags to be used in the given context. Examples ======== >>> from sympy.polys.polyoptions import allowed_flags >>> from sympy.polys.domains import ZZ >>> allowed_flags({'domain': ZZ}, []) >>> allowed_flags({'domain': ZZ, 'frac': True}, []) Traceback (most recent call last): ... FlagError: 'frac' flag is not allowed in this context >>> allowed_flags({'domain': ZZ, 'frac': True}, ['frac']) """ flags = set(flags) for arg in args.keys(): try: if Options.__options__[arg].is_Flag and not arg in flags: raise FlagError( "'%s' flag is not allowed in this context" % arg) except KeyError: raise OptionError("'%s' is not a valid option" % arg) def set_defaults(options, **defaults): """Update options with default values. """ if 'defaults' not in options: options = dict(options) options['defaults'] = defaults return options Options._init_dependencies_order()

688445860665561413932e4b203a6bd9a27d4df06d8c7cfcb31205656a0427f1

"""Groebner bases algorithms. """ from __future__ import print_function, division from sympy.core.compatibility import range from sympy.core.symbol import Dummy from sympy.polys.monomials import monomial_mul, monomial_lcm, monomial_divides, term_div from sympy.polys.orderings import lex from sympy.polys.polyerrors import DomainError from sympy.polys.polyconfig import query def groebner(seq, ring, method=None): """ Computes Groebner basis for a set of polynomials in `K[X]`. Wrapper around the (default) improved Buchberger and the other algorithms for computing Groebner bases. The choice of algorithm can be changed via ``method`` argument or :func:`setup` from :mod:`sympy.polys.polyconfig`, where ``method`` can be either ``buchberger`` or ``f5b``. """ if method is None: method = query('groebner') _groebner_methods = { 'buchberger': _buchberger, 'f5b': _f5b, } try: _groebner = _groebner_methods[method] except KeyError: raise ValueError("'%s' is not a valid Groebner bases algorithm (valid are 'buchberger' and 'f5b')" % method) domain, orig = ring.domain, None if not domain.is_Field or not domain.has_assoc_Field: try: orig, ring = ring, ring.clone(domain=domain.get_field()) except DomainError: raise DomainError("can't compute a Groebner basis over %s" % domain) else: seq = [ s.set_ring(ring) for s in seq ] G = _groebner(seq, ring) if orig is not None: G = [ g.clear_denoms()[1].set_ring(orig) for g in G ] return G def _buchberger(f, ring): """ Computes Groebner basis for a set of polynomials in `K[X]`. Given a set of multivariate polynomials `F`, finds another set `G`, such that Ideal `F = Ideal G` and `G` is a reduced Groebner basis. The resulting basis is unique and has monic generators if the ground domains is a field. Otherwise the result is non-unique but Groebner bases over e.g. integers can be computed (if the input polynomials are monic). Groebner bases can be used to choose specific generators for a polynomial ideal. Because these bases are unique you can check for ideal equality by comparing the Groebner bases. To see if one polynomial lies in an ideal, divide by the elements in the base and see if the remainder vanishes. They can also be used to solve systems of polynomial equations as, by choosing lexicographic ordering, you can eliminate one variable at a time, provided that the ideal is zero-dimensional (finite number of solutions). Notes ===== Algorithm used: an improved version of Buchberger's algorithm as presented in T. Becker, V. Weispfenning, Groebner Bases: A Computational Approach to Commutative Algebra, Springer, 1993, page 232. References ========== .. [1] [Bose03]_ .. [2] [Giovini91]_ .. [3] [Ajwa95]_ .. [4] [Cox97]_ """ order = ring.order monomial_mul = ring.monomial_mul monomial_div = ring.monomial_div monomial_lcm = ring.monomial_lcm def select(P): # normal selection strategy # select the pair with minimum LCM(LM(f), LM(g)) pr = min(P, key=lambda pair: order(monomial_lcm(f[pair[0]].LM, f[pair[1]].LM))) return pr def normal(g, J): h = g.rem([ f[j] for j in J ]) if not h: return None else: h = h.monic() if not h in I: I[h] = len(f) f.append(h) return h.LM, I[h] def update(G, B, ih): # update G using the set of critical pairs B and h # [BW] page 230 h = f[ih] mh = h.LM # filter new pairs (h, g), g in G C = G.copy() D = set() while C: # select a pair (h, g) by popping an element from C ig = C.pop() g = f[ig] mg = g.LM LCMhg = monomial_lcm(mh, mg) def lcm_divides(ip): # LCM(LM(h), LM(p)) divides LCM(LM(h), LM(g)) m = monomial_lcm(mh, f[ip].LM) return monomial_div(LCMhg, m) # HT(h) and HT(g) disjoint: mh*mg == LCMhg if monomial_mul(mh, mg) == LCMhg or ( not any(lcm_divides(ipx) for ipx in C) and not any(lcm_divides(pr[1]) for pr in D)): D.add((ih, ig)) E = set() while D: # select h, g from D (h the same as above) ih, ig = D.pop() mg = f[ig].LM LCMhg = monomial_lcm(mh, mg) if not monomial_mul(mh, mg) == LCMhg: E.add((ih, ig)) # filter old pairs B_new = set() while B: # select g1, g2 from B (-> CP) ig1, ig2 = B.pop() mg1 = f[ig1].LM mg2 = f[ig2].LM LCM12 = monomial_lcm(mg1, mg2) # if HT(h) does not divide lcm(HT(g1), HT(g2)) if not monomial_div(LCM12, mh) or \ monomial_lcm(mg1, mh) == LCM12 or \ monomial_lcm(mg2, mh) == LCM12: B_new.add((ig1, ig2)) B_new |= E # filter polynomials G_new = set() while G: ig = G.pop() mg = f[ig].LM if not monomial_div(mg, mh): G_new.add(ig) G_new.add(ih) return G_new, B_new # end of update ################################ if not f: return [] # replace f with a reduced list of initial polynomials; see [BW] page 203 f1 = f[:] while True: f = f1[:] f1 = [] for i in range(len(f)): p = f[i] r = p.rem(f[:i]) if r: f1.append(r.monic()) if f == f1: break I = {} # ip = I[p]; p = f[ip] F = set() # set of indices of polynomials G = set() # set of indices of intermediate would-be Groebner basis CP = set() # set of pairs of indices of critical pairs for i, h in enumerate(f): I[h] = i F.add(i) ##################################### # algorithm GROEBNERNEWS2 in [BW] page 232 while F: # select p with minimum monomial according to the monomial ordering h = min([f[x] for x in F], key=lambda f: order(f.LM)) ih = I[h] F.remove(ih) G, CP = update(G, CP, ih) # count the number of critical pairs which reduce to zero reductions_to_zero = 0 while CP: ig1, ig2 = select(CP) CP.remove((ig1, ig2)) h = spoly(f[ig1], f[ig2], ring) # ordering divisors is on average more efficient [Cox] page 111 G1 = sorted(G, key=lambda g: order(f[g].LM)) ht = normal(h, G1) if ht: G, CP = update(G, CP, ht[1]) else: reductions_to_zero += 1 ###################################### # now G is a Groebner basis; reduce it Gr = set() for ig in G: ht = normal(f[ig], G - set([ig])) if ht: Gr.add(ht[1]) Gr = [f[ig] for ig in Gr] # order according to the monomial ordering Gr = sorted(Gr, key=lambda f: order(f.LM), reverse=True) return Gr def spoly(p1, p2, ring): """ Compute LCM(LM(p1), LM(p2))/LM(p1)*p1 - LCM(LM(p1), LM(p2))/LM(p2)*p2 This is the S-poly provided p1 and p2 are monic """ LM1 = p1.LM LM2 = p2.LM LCM12 = ring.monomial_lcm(LM1, LM2) m1 = ring.monomial_div(LCM12, LM1) m2 = ring.monomial_div(LCM12, LM2) s1 = p1.mul_monom(m1) s2 = p2.mul_monom(m2) s = s1 - s2 return s # F5B # convenience functions def Sign(f): return f[0] def Polyn(f): return f[1] def Num(f): return f[2] def sig(monomial, index): return (monomial, index) def lbp(signature, polynomial, number): return (signature, polynomial, number) # signature functions def sig_cmp(u, v, order): """ Compare two signatures by extending the term order to K[X]^n. u < v iff - the index of v is greater than the index of u or - the index of v is equal to the index of u and u[0] < v[0] w.r.t. order u > v otherwise """ if u[1] > v[1]: return -1 if u[1] == v[1]: #if u[0] == v[0]: # return 0 if order(u[0]) < order(v[0]): return -1 return 1 def sig_key(s, order): """ Key for comparing two signatures. s = (m, k), t = (n, l) s < t iff [k > l] or [k == l and m < n] s > t otherwise """ return (-s[1], order(s[0])) def sig_mult(s, m): """ Multiply a signature by a monomial. The product of a signature (m, i) and a monomial n is defined as (m * t, i). """ return sig(monomial_mul(s[0], m), s[1]) # labeled polynomial functions def lbp_sub(f, g): """ Subtract labeled polynomial g from f. The signature and number of the difference of f and g are signature and number of the maximum of f and g, w.r.t. lbp_cmp. """ if sig_cmp(Sign(f), Sign(g), Polyn(f).ring.order) < 0: max_poly = g else: max_poly = f ret = Polyn(f) - Polyn(g) return lbp(Sign(max_poly), ret, Num(max_poly)) def lbp_mul_term(f, cx): """ Multiply a labeled polynomial with a term. The product of a labeled polynomial (s, p, k) by a monomial is defined as (m * s, m * p, k). """ return lbp(sig_mult(Sign(f), cx[0]), Polyn(f).mul_term(cx), Num(f)) def lbp_cmp(f, g): """ Compare two labeled polynomials. f < g iff - Sign(f) < Sign(g) or - Sign(f) == Sign(g) and Num(f) > Num(g) f > g otherwise """ if sig_cmp(Sign(f), Sign(g), Polyn(f).ring.order) == -1: return -1 if Sign(f) == Sign(g): if Num(f) > Num(g): return -1 #if Num(f) == Num(g): # return 0 return 1 def lbp_key(f): """ Key for comparing two labeled polynomials. """ return (sig_key(Sign(f), Polyn(f).ring.order), -Num(f)) # algorithm and helper functions def critical_pair(f, g, ring): """ Compute the critical pair corresponding to two labeled polynomials. A critical pair is a tuple (um, f, vm, g), where um and vm are terms such that um * f - vm * g is the S-polynomial of f and g (so, wlog assume um * f > vm * g). For performance sake, a critical pair is represented as a tuple (Sign(um * f), um, f, Sign(vm * g), vm, g), since um * f creates a new, relatively expensive object in memory, whereas Sign(um * f) and um are lightweight and f (in the tuple) is a reference to an already existing object in memory. """ domain = ring.domain ltf = Polyn(f).LT ltg = Polyn(g).LT lt = (monomial_lcm(ltf[0], ltg[0]), domain.one) um = term_div(lt, ltf, domain) vm = term_div(lt, ltg, domain) # The full information is not needed (now), so only the product # with the leading term is considered: fr = lbp_mul_term(lbp(Sign(f), Polyn(f).leading_term(), Num(f)), um) gr = lbp_mul_term(lbp(Sign(g), Polyn(g).leading_term(), Num(g)), vm) # return in proper order, such that the S-polynomial is just # u_first * f_first - u_second * f_second: if lbp_cmp(fr, gr) == -1: return (Sign(gr), vm, g, Sign(fr), um, f) else: return (Sign(fr), um, f, Sign(gr), vm, g) def cp_cmp(c, d): """ Compare two critical pairs c and d. c < d iff - lbp(c[0], _, Num(c[2]) < lbp(d[0], _, Num(d[2])) (this corresponds to um_c * f_c and um_d * f_d) or - lbp(c[0], _, Num(c[2]) >< lbp(d[0], _, Num(d[2])) and lbp(c[3], _, Num(c[5])) < lbp(d[3], _, Num(d[5])) (this corresponds to vm_c * g_c and vm_d * g_d) c > d otherwise """ zero = Polyn(c[2]).ring.zero c0 = lbp(c[0], zero, Num(c[2])) d0 = lbp(d[0], zero, Num(d[2])) r = lbp_cmp(c0, d0) if r == -1: return -1 if r == 0: c1 = lbp(c[3], zero, Num(c[5])) d1 = lbp(d[3], zero, Num(d[5])) r = lbp_cmp(c1, d1) if r == -1: return -1 #if r == 0: # return 0 return 1 def cp_key(c, ring): """ Key for comparing critical pairs. """ return (lbp_key(lbp(c[0], ring.zero, Num(c[2]))), lbp_key(lbp(c[3], ring.zero, Num(c[5])))) def s_poly(cp): """ Compute the S-polynomial of a critical pair. The S-polynomial of a critical pair cp is cp[1] * cp[2] - cp[4] * cp[5]. """ return lbp_sub(lbp_mul_term(cp[2], cp[1]), lbp_mul_term(cp[5], cp[4])) def is_rewritable_or_comparable(sign, num, B): """ Check if a labeled polynomial is redundant by checking if its signature and number imply rewritability or comparability. (sign, num) is comparable if there exists a labeled polynomial h in B, such that sign[1] (the index) is less than Sign(h)[1] and sign[0] is divisible by the leading monomial of h. (sign, num) is rewritable if there exists a labeled polynomial h in B, such thatsign[1] is equal to Sign(h)[1], num < Num(h) and sign[0] is divisible by Sign(h)[0]. """ for h in B: # comparable if sign[1] < Sign(h)[1]: if monomial_divides(Polyn(h).LM, sign[0]): return True # rewritable if sign[1] == Sign(h)[1]: if num < Num(h): if monomial_divides(Sign(h)[0], sign[0]): return True return False def f5_reduce(f, B): """ F5-reduce a labeled polynomial f by B. Continuously searches for non-zero labeled polynomial h in B, such that the leading term lt_h of h divides the leading term lt_f of f and Sign(lt_h * h) < Sign(f). If such a labeled polynomial h is found, f gets replaced by f - lt_f / lt_h * h. If no such h can be found or f is 0, f is no further F5-reducible and f gets returned. A polynomial that is reducible in the usual sense need not be F5-reducible, e.g.: >>> from sympy.polys.groebnertools import lbp, sig, f5_reduce, Polyn >>> from sympy.polys import ring, QQ, lex >>> R, x,y,z = ring("x,y,z", QQ, lex) >>> f = lbp(sig((1, 1, 1), 4), x, 3) >>> g = lbp(sig((0, 0, 0), 2), x, 2) >>> Polyn(f).rem([Polyn(g)]) 0 >>> f5_reduce(f, [g]) (((1, 1, 1), 4), x, 3) """ order = Polyn(f).ring.order domain = Polyn(f).ring.domain if not Polyn(f): return f while True: g = f for h in B: if Polyn(h): if monomial_divides(Polyn(h).LM, Polyn(f).LM): t = term_div(Polyn(f).LT, Polyn(h).LT, domain) if sig_cmp(sig_mult(Sign(h), t[0]), Sign(f), order) < 0: # The following check need not be done and is in general slower than without. #if not is_rewritable_or_comparable(Sign(gp), Num(gp), B): hp = lbp_mul_term(h, t) f = lbp_sub(f, hp) break if g == f or not Polyn(f): return f def _f5b(F, ring): """ Computes a reduced Groebner basis for the ideal generated by F. f5b is an implementation of the F5B algorithm by Yao Sun and Dingkang Wang. Similarly to Buchberger's algorithm, the algorithm proceeds by computing critical pairs, computing the S-polynomial, reducing it and adjoining the reduced S-polynomial if it is not 0. Unlike Buchberger's algorithm, each polynomial contains additional information, namely a signature and a number. The signature specifies the path of computation (i.e. from which polynomial in the original basis was it derived and how), the number says when the polynomial was added to the basis. With this information it is (often) possible to decide if an S-polynomial will reduce to 0 and can be discarded. Optimizations include: Reducing the generators before computing a Groebner basis, removing redundant critical pairs when a new polynomial enters the basis and sorting the critical pairs and the current basis. Once a Groebner basis has been found, it gets reduced. References ========== .. [1] Yao Sun, Dingkang Wang: "A New Proof for the Correctness of F5 (F5-Like) Algorithm", http://arxiv.org/abs/1004.0084 (specifically v4) .. [2] Thomas Becker, Volker Weispfenning, Groebner bases: A computational approach to commutative algebra, 1993, p. 203, 216 """ order = ring.order # reduce polynomials (like in Mario Pernici's implementation) (Becker, Weispfenning, p. 203) B = F while True: F = B B = [] for i in range(len(F)): p = F[i] r = p.rem(F[:i]) if r: B.append(r) if F == B: break # basis B = [lbp(sig(ring.zero_monom, i + 1), F[i], i + 1) for i in range(len(F))] B.sort(key=lambda f: order(Polyn(f).LM), reverse=True) # critical pairs CP = [critical_pair(B[i], B[j], ring) for i in range(len(B)) for j in range(i + 1, len(B))] CP.sort(key=lambda cp: cp_key(cp, ring), reverse=True) k = len(B) reductions_to_zero = 0 while len(CP): cp = CP.pop() # discard redundant critical pairs: if is_rewritable_or_comparable(cp[0], Num(cp[2]), B): continue if is_rewritable_or_comparable(cp[3], Num(cp[5]), B): continue s = s_poly(cp) p = f5_reduce(s, B) p = lbp(Sign(p), Polyn(p).monic(), k + 1) if Polyn(p): # remove old critical pairs, that become redundant when adding p: indices = [] for i, cp in enumerate(CP): if is_rewritable_or_comparable(cp[0], Num(cp[2]), [p]): indices.append(i) elif is_rewritable_or_comparable(cp[3], Num(cp[5]), [p]): indices.append(i) for i in reversed(indices): del CP[i] # only add new critical pairs that are not made redundant by p: for g in B: if Polyn(g): cp = critical_pair(p, g, ring) if is_rewritable_or_comparable(cp[0], Num(cp[2]), [p]): continue elif is_rewritable_or_comparable(cp[3], Num(cp[5]), [p]): continue CP.append(cp) # sort (other sorting methods/selection strategies were not as successful) CP.sort(key=lambda cp: cp_key(cp, ring), reverse=True) # insert p into B: m = Polyn(p).LM if order(m) <= order(Polyn(B[-1]).LM): B.append(p) else: for i, q in enumerate(B): if order(m) > order(Polyn(q).LM): B.insert(i, p) break k += 1 #print(len(B), len(CP), "%d critical pairs removed" % len(indices)) else: reductions_to_zero += 1 # reduce Groebner basis: H = [Polyn(g).monic() for g in B] H = red_groebner(H, ring) return sorted(H, key=lambda f: order(f.LM), reverse=True) def red_groebner(G, ring): """ Compute reduced Groebner basis, from BeckerWeispfenning93, p. 216 Selects a subset of generators, that already generate the ideal and computes a reduced Groebner basis for them. """ def reduction(P): """ The actual reduction algorithm. """ Q = [] for i, p in enumerate(P): h = p.rem(P[:i] + P[i + 1:]) if h: Q.append(h) return [p.monic() for p in Q] F = G H = [] while F: f0 = F.pop() if not any(monomial_divides(f.LM, f0.LM) for f in F + H): H.append(f0) # Becker, Weispfenning, p. 217: H is Groebner basis of the ideal generated by G. return reduction(H) def is_groebner(G, ring): """ Check if G is a Groebner basis. """ for i in range(len(G)): for j in range(i + 1, len(G)): s = spoly(G[i], G[j], ring) s = s.rem(G) if s: return False return True def is_minimal(G, ring): """ Checks if G is a minimal Groebner basis. """ order = ring.order domain = ring.domain G.sort(key=lambda g: order(g.LM)) for i, g in enumerate(G): if g.LC != domain.one: return False for h in G[:i] + G[i + 1:]: if monomial_divides(h.LM, g.LM): return False return True def is_reduced(G, ring): """ Checks if G is a reduced Groebner basis. """ order = ring.order domain = ring.domain G.sort(key=lambda g: order(g.LM)) for i, g in enumerate(G): if g.LC != domain.one: return False for term in g: for h in G[:i] + G[i + 1:]: if monomial_divides(h.LM, term[0]): return False return True def groebner_lcm(f, g): """ Computes LCM of two polynomials using Groebner bases. The LCM is computed as the unique generator of the intersection of the two ideals generated by `f` and `g`. The approach is to compute a Groebner basis with respect to lexicographic ordering of `t*f` and `(1 - t)*g`, where `t` is an unrelated variable and then filtering out the solution that doesn't contain `t`. References ========== .. [1] [Cox97]_ """ if f.ring != g.ring: raise ValueError("Values should be equal") ring = f.ring domain = ring.domain if not f or not g: return ring.zero if len(f) <= 1 and len(g) <= 1: monom = monomial_lcm(f.LM, g.LM) coeff = domain.lcm(f.LC, g.LC) return ring.term_new(monom, coeff) fc, f = f.primitive() gc, g = g.primitive() lcm = domain.lcm(fc, gc) f_terms = [ ((1,) + monom, coeff) for monom, coeff in f.terms() ] g_terms = [ ((0,) + monom, coeff) for monom, coeff in g.terms() ] \ + [ ((1,) + monom,-coeff) for monom, coeff in g.terms() ] t = Dummy("t") t_ring = ring.clone(symbols=(t,) + ring.symbols, order=lex) F = t_ring.from_terms(f_terms) G = t_ring.from_terms(g_terms) basis = groebner([F, G], t_ring) def is_independent(h, j): return all(not monom[j] for monom in h.monoms()) H = [ h for h in basis if is_independent(h, 0) ] h_terms = [ (monom[1:], coeff*lcm) for monom, coeff in H[0].terms() ] h = ring.from_terms(h_terms) return h def groebner_gcd(f, g): """Computes GCD of two polynomials using Groebner bases. """ if f.ring != g.ring: raise ValueError("Values should be equal") domain = f.ring.domain if not domain.is_Field: fc, f = f.primitive() gc, g = g.primitive() gcd = domain.gcd(fc, gc) H = (f*g).quo([groebner_lcm(f, g)]) if len(H) != 1: raise ValueError("Length should be 1") h = H[0] if not domain.is_Field: return gcd*h else: return h.monic()

624776ff4341eff352b24bc0ebf8ddaf2e9ff0170adfe4e3b05fc4d77ad52c67

from sympy import Dummy from sympy.core.compatibility import range from sympy.ntheory import nextprime from sympy.ntheory.modular import crt from sympy.polys.domains import PolynomialRing from sympy.polys.galoistools import ( gf_gcd, gf_from_dict, gf_gcdex, gf_div, gf_lcm) from sympy.polys.polyerrors import ModularGCDFailed from mpmath import sqrt import random def _trivial_gcd(f, g): """ Compute the GCD of two polynomials in trivial cases, i.e. when one or both polynomials are zero. """ ring = f.ring if not (f or g): return ring.zero, ring.zero, ring.zero elif not f: if g.LC < ring.domain.zero: return -g, ring.zero, -ring.one else: return g, ring.zero, ring.one elif not g: if f.LC < ring.domain.zero: return -f, -ring.one, ring.zero else: return f, ring.one, ring.zero return None def _gf_gcd(fp, gp, p): r""" Compute the GCD of two univariate polynomials in `\mathbb{Z}_p[x]`. """ dom = fp.ring.domain while gp: rem = fp deg = gp.degree() lcinv = dom.invert(gp.LC, p) while True: degrem = rem.degree() if degrem < deg: break rem = (rem - gp.mul_monom((degrem - deg,)).mul_ground(lcinv * rem.LC)).trunc_ground(p) fp = gp gp = rem return fp.mul_ground(dom.invert(fp.LC, p)).trunc_ground(p) def _degree_bound_univariate(f, g): r""" Compute an upper bound for the degree of the GCD of two univariate integer polynomials `f` and `g`. The function chooses a suitable prime `p` and computes the GCD of `f` and `g` in `\mathbb{Z}_p[x]`. The choice of `p` guarantees that the degree in `\mathbb{Z}_p[x]` is greater than or equal to the degree in `\mathbb{Z}[x]`. Parameters ========== f : PolyElement univariate integer polynomial g : PolyElement univariate integer polynomial """ gamma = f.ring.domain.gcd(f.LC, g.LC) p = 1 p = nextprime(p) while gamma % p == 0: p = nextprime(p) fp = f.trunc_ground(p) gp = g.trunc_ground(p) hp = _gf_gcd(fp, gp, p) deghp = hp.degree() return deghp def _chinese_remainder_reconstruction_univariate(hp, hq, p, q): r""" Construct a polynomial `h_{pq}` in `\mathbb{Z}_{p q}[x]` such that .. math :: h_{pq} = h_p \; \mathrm{mod} \, p h_{pq} = h_q \; \mathrm{mod} \, q for relatively prime integers `p` and `q` and polynomials `h_p` and `h_q` in `\mathbb{Z}_p[x]` and `\mathbb{Z}_q[x]` respectively. The coefficients of the polynomial `h_{pq}` are computed with the Chinese Remainder Theorem. The symmetric representation in `\mathbb{Z}_p[x]`, `\mathbb{Z}_q[x]` and `\mathbb{Z}_{p q}[x]` is used. It is assumed that `h_p` and `h_q` have the same degree. Parameters ========== hp : PolyElement univariate integer polynomial with coefficients in `\mathbb{Z}_p` hq : PolyElement univariate integer polynomial with coefficients in `\mathbb{Z}_q` p : Integer modulus of `h_p`, relatively prime to `q` q : Integer modulus of `h_q`, relatively prime to `p` Examples ======== >>> from sympy.polys.modulargcd import _chinese_remainder_reconstruction_univariate >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> p = 3 >>> q = 5 >>> hp = -x**3 - 1 >>> hq = 2*x**3 - 2*x**2 + x >>> hpq = _chinese_remainder_reconstruction_univariate(hp, hq, p, q) >>> hpq 2*x**3 + 3*x**2 + 6*x + 5 >>> hpq.trunc_ground(p) == hp True >>> hpq.trunc_ground(q) == hq True """ n = hp.degree() x = hp.ring.gens[0] hpq = hp.ring.zero for i in range(n+1): hpq[(i,)] = crt([p, q], [hp.coeff(x**i), hq.coeff(x**i)], symmetric=True)[0] hpq.strip_zero() return hpq def modgcd_univariate(f, g): r""" Computes the GCD of two polynomials in `\mathbb{Z}[x]` using a modular algorithm. The algorithm computes the GCD of two univariate integer polynomials `f` and `g` by computing the GCD in `\mathbb{Z}_p[x]` for suitable primes `p` and then reconstructing the coefficients with the Chinese Remainder Theorem. Trial division is only made for candidates which are very likely the desired GCD. Parameters ========== f : PolyElement univariate integer polynomial g : PolyElement univariate integer polynomial Returns ======= h : PolyElement GCD of the polynomials `f` and `g` cff : PolyElement cofactor of `f`, i.e. `\frac{f}{h}` cfg : PolyElement cofactor of `g`, i.e. `\frac{g}{h}` Examples ======== >>> from sympy.polys.modulargcd import modgcd_univariate >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> f = x**5 - 1 >>> g = x - 1 >>> h, cff, cfg = modgcd_univariate(f, g) >>> h, cff, cfg (x - 1, x**4 + x**3 + x**2 + x + 1, 1) >>> cff * h == f True >>> cfg * h == g True >>> f = 6*x**2 - 6 >>> g = 2*x**2 + 4*x + 2 >>> h, cff, cfg = modgcd_univariate(f, g) >>> h, cff, cfg (2*x + 2, 3*x - 3, x + 1) >>> cff * h == f True >>> cfg * h == g True References ========== 1. [Monagan00]_ """ assert f.ring == g.ring and f.ring.domain.is_ZZ result = _trivial_gcd(f, g) if result is not None: return result ring = f.ring cf, f = f.primitive() cg, g = g.primitive() ch = ring.domain.gcd(cf, cg) bound = _degree_bound_univariate(f, g) if bound == 0: return ring(ch), f.mul_ground(cf // ch), g.mul_ground(cg // ch) gamma = ring.domain.gcd(f.LC, g.LC) m = 1 p = 1 while True: p = nextprime(p) while gamma % p == 0: p = nextprime(p) fp = f.trunc_ground(p) gp = g.trunc_ground(p) hp = _gf_gcd(fp, gp, p) deghp = hp.degree() if deghp > bound: continue elif deghp < bound: m = 1 bound = deghp continue hp = hp.mul_ground(gamma).trunc_ground(p) if m == 1: m = p hlastm = hp continue hm = _chinese_remainder_reconstruction_univariate(hp, hlastm, p, m) m *= p if not hm == hlastm: hlastm = hm continue h = hm.quo_ground(hm.content()) fquo, frem = f.div(h) gquo, grem = g.div(h) if not frem and not grem: if h.LC < 0: ch = -ch h = h.mul_ground(ch) cff = fquo.mul_ground(cf // ch) cfg = gquo.mul_ground(cg // ch) return h, cff, cfg def _primitive(f, p): r""" Compute the content and the primitive part of a polynomial in `\mathbb{Z}_p[x_0, \ldots, x_{k-2}, y] \cong \mathbb{Z}_p[y][x_0, \ldots, x_{k-2}]`. Parameters ========== f : PolyElement integer polynomial in `\mathbb{Z}_p[x0, \ldots, x{k-2}, y]` p : Integer modulus of `f` Returns ======= contf : PolyElement integer polynomial in `\mathbb{Z}_p[y]`, content of `f` ppf : PolyElement primitive part of `f`, i.e. `\frac{f}{contf}` Examples ======== >>> from sympy.polys.modulargcd import _primitive >>> from sympy.polys import ring, ZZ >>> R, x, y = ring("x, y", ZZ) >>> p = 3 >>> f = x**2*y**2 + x**2*y - y**2 - y >>> _primitive(f, p) (y**2 + y, x**2 - 1) >>> R, x, y, z = ring("x, y, z", ZZ) >>> f = x*y*z - y**2*z**2 >>> _primitive(f, p) (z, x*y - y**2*z) """ ring = f.ring dom = ring.domain k = ring.ngens coeffs = {} for monom, coeff in f.iterterms(): if monom[:-1] not in coeffs: coeffs[monom[:-1]] = {} coeffs[monom[:-1]][monom[-1]] = coeff cont = [] for coeff in iter(coeffs.values()): cont = gf_gcd(cont, gf_from_dict(coeff, p, dom), p, dom) yring = ring.clone(symbols=ring.symbols[k-1]) contf = yring.from_dense(cont).trunc_ground(p) return contf, f.quo(contf.set_ring(ring)) def _deg(f): r""" Compute the degree of a multivariate polynomial `f \in K[x_0, \ldots, x_{k-2}, y] \cong K[y][x_0, \ldots, x_{k-2}]`. Parameters ========== f : PolyElement polynomial in `K[x_0, \ldots, x_{k-2}, y]` Returns ======= degf : Integer tuple degree of `f` in `x_0, \ldots, x_{k-2}` Examples ======== >>> from sympy.polys.modulargcd import _deg >>> from sympy.polys import ring, ZZ >>> R, x, y = ring("x, y", ZZ) >>> f = x**2*y**2 + x**2*y - 1 >>> _deg(f) (2,) >>> R, x, y, z = ring("x, y, z", ZZ) >>> f = x**2*y**2 + x**2*y - 1 >>> _deg(f) (2, 2) >>> f = x*y*z - y**2*z**2 >>> _deg(f) (1, 1) """ k = f.ring.ngens degf = (0,) * (k-1) for monom in f.itermonoms(): if monom[:-1] > degf: degf = monom[:-1] return degf def _LC(f): r""" Compute the leading coefficient of a multivariate polynomial `f \in K[x_0, \ldots, x_{k-2}, y] \cong K[y][x_0, \ldots, x_{k-2}]`. Parameters ========== f : PolyElement polynomial in `K[x_0, \ldots, x_{k-2}, y]` Returns ======= lcf : PolyElement polynomial in `K[y]`, leading coefficient of `f` Examples ======== >>> from sympy.polys.modulargcd import _LC >>> from sympy.polys import ring, ZZ >>> R, x, y = ring("x, y", ZZ) >>> f = x**2*y**2 + x**2*y - 1 >>> _LC(f) y**2 + y >>> R, x, y, z = ring("x, y, z", ZZ) >>> f = x**2*y**2 + x**2*y - 1 >>> _LC(f) 1 >>> f = x*y*z - y**2*z**2 >>> _LC(f) z """ ring = f.ring k = ring.ngens yring = ring.clone(symbols=ring.symbols[k-1]) y = yring.gens[0] degf = _deg(f) lcf = yring.zero for monom, coeff in f.iterterms(): if monom[:-1] == degf: lcf += coeff*y**monom[-1] return lcf def _swap(f, i): """ Make the variable `x_i` the leading one in a multivariate polynomial `f`. """ ring = f.ring fswap = ring.zero for monom, coeff in f.iterterms(): monomswap = (monom[i],) + monom[:i] + monom[i+1:] fswap[monomswap] = coeff return fswap def _degree_bound_bivariate(f, g): r""" Compute upper degree bounds for the GCD of two bivariate integer polynomials `f` and `g`. The GCD is viewed as a polynomial in `\mathbb{Z}[y][x]` and the function returns an upper bound for its degree and one for the degree of its content. This is done by choosing a suitable prime `p` and computing the GCD of the contents of `f \; \mathrm{mod} \, p` and `g \; \mathrm{mod} \, p`. The choice of `p` guarantees that the degree of the content in `\mathbb{Z}_p[y]` is greater than or equal to the degree in `\mathbb{Z}[y]`. To obtain the degree bound in the variable `x`, the polynomials are evaluated at `y = a` for a suitable `a \in \mathbb{Z}_p` and then their GCD in `\mathbb{Z}_p[x]` is computed. If no such `a` exists, i.e. the degree in `\mathbb{Z}_p[x]` is always smaller than the one in `\mathbb{Z}[y][x]`, then the bound is set to the minimum of the degrees of `f` and `g` in `x`. Parameters ========== f : PolyElement bivariate integer polynomial g : PolyElement bivariate integer polynomial Returns ======= xbound : Integer upper bound for the degree of the GCD of the polynomials `f` and `g` in the variable `x` ycontbound : Integer upper bound for the degree of the content of the GCD of the polynomials `f` and `g` in the variable `y` References ========== 1. [Monagan00]_ """ ring = f.ring gamma1 = ring.domain.gcd(f.LC, g.LC) gamma2 = ring.domain.gcd(_swap(f, 1).LC, _swap(g, 1).LC) badprimes = gamma1 * gamma2 p = 1 p = nextprime(p) while badprimes % p == 0: p = nextprime(p) fp = f.trunc_ground(p) gp = g.trunc_ground(p) contfp, fp = _primitive(fp, p) contgp, gp = _primitive(gp, p) conthp = _gf_gcd(contfp, contgp, p) # polynomial in Z_p[y] ycontbound = conthp.degree() # polynomial in Z_p[y] delta = _gf_gcd(_LC(fp), _LC(gp), p) for a in range(p): if not delta.evaluate(0, a) % p: continue fpa = fp.evaluate(1, a).trunc_ground(p) gpa = gp.evaluate(1, a).trunc_ground(p) hpa = _gf_gcd(fpa, gpa, p) xbound = hpa.degree() return xbound, ycontbound return min(fp.degree(), gp.degree()), ycontbound def _chinese_remainder_reconstruction_multivariate(hp, hq, p, q): r""" Construct a polynomial `h_{pq}` in `\mathbb{Z}_{p q}[x_0, \ldots, x_{k-1}]` such that .. math :: h_{pq} = h_p \; \mathrm{mod} \, p h_{pq} = h_q \; \mathrm{mod} \, q for relatively prime integers `p` and `q` and polynomials `h_p` and `h_q` in `\mathbb{Z}_p[x_0, \ldots, x_{k-1}]` and `\mathbb{Z}_q[x_0, \ldots, x_{k-1}]` respectively. The coefficients of the polynomial `h_{pq}` are computed with the Chinese Remainder Theorem. The symmetric representation in `\mathbb{Z}_p[x_0, \ldots, x_{k-1}]`, `\mathbb{Z}_q[x_0, \ldots, x_{k-1}]` and `\mathbb{Z}_{p q}[x_0, \ldots, x_{k-1}]` is used. Parameters ========== hp : PolyElement multivariate integer polynomial with coefficients in `\mathbb{Z}_p` hq : PolyElement multivariate integer polynomial with coefficients in `\mathbb{Z}_q` p : Integer modulus of `h_p`, relatively prime to `q` q : Integer modulus of `h_q`, relatively prime to `p` Examples ======== >>> from sympy.polys.modulargcd import _chinese_remainder_reconstruction_multivariate >>> from sympy.polys import ring, ZZ >>> R, x, y = ring("x, y", ZZ) >>> p = 3 >>> q = 5 >>> hp = x**3*y - x**2 - 1 >>> hq = -x**3*y - 2*x*y**2 + 2 >>> hpq = _chinese_remainder_reconstruction_multivariate(hp, hq, p, q) >>> hpq 4*x**3*y + 5*x**2 + 3*x*y**2 + 2 >>> hpq.trunc_ground(p) == hp True >>> hpq.trunc_ground(q) == hq True >>> R, x, y, z = ring("x, y, z", ZZ) >>> p = 6 >>> q = 5 >>> hp = 3*x**4 - y**3*z + z >>> hq = -2*x**4 + z >>> hpq = _chinese_remainder_reconstruction_multivariate(hp, hq, p, q) >>> hpq 3*x**4 + 5*y**3*z + z >>> hpq.trunc_ground(p) == hp True >>> hpq.trunc_ground(q) == hq True """ hpmonoms = set(hp.monoms()) hqmonoms = set(hq.monoms()) monoms = hpmonoms.intersection(hqmonoms) hpmonoms.difference_update(monoms) hqmonoms.difference_update(monoms) zero = hp.ring.domain.zero hpq = hp.ring.zero if isinstance(hp.ring.domain, PolynomialRing): crt_ = _chinese_remainder_reconstruction_multivariate else: def crt_(cp, cq, p, q): return crt([p, q], [cp, cq], symmetric=True)[0] for monom in monoms: hpq[monom] = crt_(hp[monom], hq[monom], p, q) for monom in hpmonoms: hpq[monom] = crt_(hp[monom], zero, p, q) for monom in hqmonoms: hpq[monom] = crt_(zero, hq[monom], p, q) return hpq def _interpolate_multivariate(evalpoints, hpeval, ring, i, p, ground=False): r""" Reconstruct a polynomial `h_p` in `\mathbb{Z}_p[x_0, \ldots, x_{k-1}]` from a list of evaluation points in `\mathbb{Z}_p` and a list of polynomials in `\mathbb{Z}_p[x_0, \ldots, x_{i-1}, x_{i+1}, \ldots, x_{k-1}]`, which are the images of `h_p` evaluated in the variable `x_i`. It is also possible to reconstruct a parameter of the ground domain, i.e. if `h_p` is a polynomial over `\mathbb{Z}_p[x_0, \ldots, x_{k-1}]`. In this case, one has to set ``ground=True``. Parameters ========== evalpoints : list of Integer objects list of evaluation points in `\mathbb{Z}_p` hpeval : list of PolyElement objects list of polynomials in (resp. over) `\mathbb{Z}_p[x_0, \ldots, x_{i-1}, x_{i+1}, \ldots, x_{k-1}]`, images of `h_p` evaluated in the variable `x_i` ring : PolyRing `h_p` will be an element of this ring i : Integer index of the variable which has to be reconstructed p : Integer prime number, modulus of `h_p` ground : Boolean indicates whether `x_i` is in the ground domain, default is ``False`` Returns ======= hp : PolyElement interpolated polynomial in (resp. over) `\mathbb{Z}_p[x_0, \ldots, x_{k-1}]` """ hp = ring.zero if ground: domain = ring.domain.domain y = ring.domain.gens[i] else: domain = ring.domain y = ring.gens[i] for a, hpa in zip(evalpoints, hpeval): numer = ring.one denom = domain.one for b in evalpoints: if b == a: continue numer *= y - b denom *= a - b denom = domain.invert(denom, p) coeff = numer.mul_ground(denom) hp += hpa.set_ring(ring) * coeff return hp.trunc_ground(p) def modgcd_bivariate(f, g): r""" Computes the GCD of two polynomials in `\mathbb{Z}[x, y]` using a modular algorithm. The algorithm computes the GCD of two bivariate integer polynomials `f` and `g` by calculating the GCD in `\mathbb{Z}_p[x, y]` for suitable primes `p` and then reconstructing the coefficients with the Chinese Remainder Theorem. To compute the bivariate GCD over `\mathbb{Z}_p`, the polynomials `f \; \mathrm{mod} \, p` and `g \; \mathrm{mod} \, p` are evaluated at `y = a` for certain `a \in \mathbb{Z}_p` and then their univariate GCD in `\mathbb{Z}_p[x]` is computed. Interpolating those yields the bivariate GCD in `\mathbb{Z}_p[x, y]`. To verify the result in `\mathbb{Z}[x, y]`, trial division is done, but only for candidates which are very likely the desired GCD. Parameters ========== f : PolyElement bivariate integer polynomial g : PolyElement bivariate integer polynomial Returns ======= h : PolyElement GCD of the polynomials `f` and `g` cff : PolyElement cofactor of `f`, i.e. `\frac{f}{h}` cfg : PolyElement cofactor of `g`, i.e. `\frac{g}{h}` Examples ======== >>> from sympy.polys.modulargcd import modgcd_bivariate >>> from sympy.polys import ring, ZZ >>> R, x, y = ring("x, y", ZZ) >>> f = x**2 - y**2 >>> g = x**2 + 2*x*y + y**2 >>> h, cff, cfg = modgcd_bivariate(f, g) >>> h, cff, cfg (x + y, x - y, x + y) >>> cff * h == f True >>> cfg * h == g True >>> f = x**2*y - x**2 - 4*y + 4 >>> g = x + 2 >>> h, cff, cfg = modgcd_bivariate(f, g) >>> h, cff, cfg (x + 2, x*y - x - 2*y + 2, 1) >>> cff * h == f True >>> cfg * h == g True References ========== 1. [Monagan00]_ """ assert f.ring == g.ring and f.ring.domain.is_ZZ result = _trivial_gcd(f, g) if result is not None: return result ring = f.ring cf, f = f.primitive() cg, g = g.primitive() ch = ring.domain.gcd(cf, cg) xbound, ycontbound = _degree_bound_bivariate(f, g) if xbound == ycontbound == 0: return ring(ch), f.mul_ground(cf // ch), g.mul_ground(cg // ch) fswap = _swap(f, 1) gswap = _swap(g, 1) degyf = fswap.degree() degyg = gswap.degree() ybound, xcontbound = _degree_bound_bivariate(fswap, gswap) if ybound == xcontbound == 0: return ring(ch), f.mul_ground(cf // ch), g.mul_ground(cg // ch) # TODO: to improve performance, choose the main variable here gamma1 = ring.domain.gcd(f.LC, g.LC) gamma2 = ring.domain.gcd(fswap.LC, gswap.LC) badprimes = gamma1 * gamma2 m = 1 p = 1 while True: p = nextprime(p) while badprimes % p == 0: p = nextprime(p) fp = f.trunc_ground(p) gp = g.trunc_ground(p) contfp, fp = _primitive(fp, p) contgp, gp = _primitive(gp, p) conthp = _gf_gcd(contfp, contgp, p) # monic polynomial in Z_p[y] degconthp = conthp.degree() if degconthp > ycontbound: continue elif degconthp < ycontbound: m = 1 ycontbound = degconthp continue # polynomial in Z_p[y] delta = _gf_gcd(_LC(fp), _LC(gp), p) degcontfp = contfp.degree() degcontgp = contgp.degree() degdelta = delta.degree() N = min(degyf - degcontfp, degyg - degcontgp, ybound - ycontbound + degdelta) + 1 if p < N: continue n = 0 evalpoints = [] hpeval = [] unlucky = False for a in range(p): deltaa = delta.evaluate(0, a) if not deltaa % p: continue fpa = fp.evaluate(1, a).trunc_ground(p) gpa = gp.evaluate(1, a).trunc_ground(p) hpa = _gf_gcd(fpa, gpa, p) # monic polynomial in Z_p[x] deghpa = hpa.degree() if deghpa > xbound: continue elif deghpa < xbound: m = 1 xbound = deghpa unlucky = True break hpa = hpa.mul_ground(deltaa).trunc_ground(p) evalpoints.append(a) hpeval.append(hpa) n += 1 if n == N: break if unlucky: continue if n < N: continue hp = _interpolate_multivariate(evalpoints, hpeval, ring, 1, p) hp = _primitive(hp, p)[1] hp = hp * conthp.set_ring(ring) degyhp = hp.degree(1) if degyhp > ybound: continue if degyhp < ybound: m = 1 ybound = degyhp continue hp = hp.mul_ground(gamma1).trunc_ground(p) if m == 1: m = p hlastm = hp continue hm = _chinese_remainder_reconstruction_multivariate(hp, hlastm, p, m) m *= p if not hm == hlastm: hlastm = hm continue h = hm.quo_ground(hm.content()) fquo, frem = f.div(h) gquo, grem = g.div(h) if not frem and not grem: if h.LC < 0: ch = -ch h = h.mul_ground(ch) cff = fquo.mul_ground(cf // ch) cfg = gquo.mul_ground(cg // ch) return h, cff, cfg def _modgcd_multivariate_p(f, g, p, degbound, contbound): r""" Compute the GCD of two polynomials in `\mathbb{Z}_p[x0, \ldots, x{k-1}]`. The algorithm reduces the problem step by step by evaluating the polynomials `f` and `g` at `x_{k-1} = a` for suitable `a \in \mathbb{Z}_p` and then calls itself recursively to compute the GCD in `\mathbb{Z}_p[x_0, \ldots, x_{k-2}]`. If these recursive calls are succsessful for enough evaluation points, the GCD in `k` variables is interpolated, otherwise the algorithm returns ``None``. Every time a GCD or a content is computed, their degrees are compared with the bounds. If a degree greater then the bound is encountered, then the current call returns ``None`` and a new evaluation point has to be chosen. If at some point the degree is smaller, the correspondent bound is updated and the algorithm fails. Parameters ========== f : PolyElement multivariate integer polynomial with coefficients in `\mathbb{Z}_p` g : PolyElement multivariate integer polynomial with coefficients in `\mathbb{Z}_p` p : Integer prime number, modulus of `f` and `g` degbound : list of Integer objects ``degbound[i]`` is an upper bound for the degree of the GCD of `f` and `g` in the variable `x_i` contbound : list of Integer objects ``contbound[i]`` is an upper bound for the degree of the content of the GCD in `\mathbb{Z}_p[x_i][x_0, \ldots, x_{i-1}]`, ``contbound[0]`` is not used can therefore be chosen arbitrarily. Returns ======= h : PolyElement GCD of the polynomials `f` and `g` or ``None`` References ========== 1. [Monagan00]_ 2. [Brown71]_ """ ring = f.ring k = ring.ngens if k == 1: h = _gf_gcd(f, g, p).trunc_ground(p) degh = h.degree() if degh > degbound[0]: return None if degh < degbound[0]: degbound[0] = degh raise ModularGCDFailed return h degyf = f.degree(k-1) degyg = g.degree(k-1) contf, f = _primitive(f, p) contg, g = _primitive(g, p) conth = _gf_gcd(contf, contg, p) # polynomial in Z_p[y] degcontf = contf.degree() degcontg = contg.degree() degconth = conth.degree() if degconth > contbound[k-1]: return None if degconth < contbound[k-1]: contbound[k-1] = degconth raise ModularGCDFailed lcf = _LC(f) lcg = _LC(g) delta = _gf_gcd(lcf, lcg, p) # polynomial in Z_p[y] evaltest = delta for i in range(k-1): evaltest *= _gf_gcd(_LC(_swap(f, i)), _LC(_swap(g, i)), p) degdelta = delta.degree() N = min(degyf - degcontf, degyg - degcontg, degbound[k-1] - contbound[k-1] + degdelta) + 1 if p < N: return None n = 0 d = 0 evalpoints = [] heval = [] points = set(range(p)) while points: a = random.sample(points, 1)[0] points.remove(a) if not evaltest.evaluate(0, a) % p: continue deltaa = delta.evaluate(0, a) % p fa = f.evaluate(k-1, a).trunc_ground(p) ga = g.evaluate(k-1, a).trunc_ground(p) # polynomials in Z_p[x_0, ..., x_{k-2}] ha = _modgcd_multivariate_p(fa, ga, p, degbound, contbound) if ha is None: d += 1 if d > n: return None continue if ha.is_ground: h = conth.set_ring(ring).trunc_ground(p) return h ha = ha.mul_ground(deltaa).trunc_ground(p) evalpoints.append(a) heval.append(ha) n += 1 if n == N: h = _interpolate_multivariate(evalpoints, heval, ring, k-1, p) h = _primitive(h, p)[1] * conth.set_ring(ring) degyh = h.degree(k-1) if degyh > degbound[k-1]: return None if degyh < degbound[k-1]: degbound[k-1] = degyh raise ModularGCDFailed return h return None def modgcd_multivariate(f, g): r""" Compute the GCD of two polynomials in `\mathbb{Z}[x_0, \ldots, x_{k-1}]` using a modular algorithm. The algorithm computes the GCD of two multivariate integer polynomials `f` and `g` by calculating the GCD in `\mathbb{Z}_p[x_0, \ldots, x_{k-1}]` for suitable primes `p` and then reconstructing the coefficients with the Chinese Remainder Theorem. To compute the multivariate GCD over `\mathbb{Z}_p` the recursive subroutine ``_modgcd_multivariate_p`` is used. To verify the result in `\mathbb{Z}[x_0, \ldots, x_{k-1}]`, trial division is done, but only for candidates which are very likely the desired GCD. Parameters ========== f : PolyElement multivariate integer polynomial g : PolyElement multivariate integer polynomial Returns ======= h : PolyElement GCD of the polynomials `f` and `g` cff : PolyElement cofactor of `f`, i.e. `\frac{f}{h}` cfg : PolyElement cofactor of `g`, i.e. `\frac{g}{h}` Examples ======== >>> from sympy.polys.modulargcd import modgcd_multivariate >>> from sympy.polys import ring, ZZ >>> R, x, y = ring("x, y", ZZ) >>> f = x**2 - y**2 >>> g = x**2 + 2*x*y + y**2 >>> h, cff, cfg = modgcd_multivariate(f, g) >>> h, cff, cfg (x + y, x - y, x + y) >>> cff * h == f True >>> cfg * h == g True >>> R, x, y, z = ring("x, y, z", ZZ) >>> f = x*z**2 - y*z**2 >>> g = x**2*z + z >>> h, cff, cfg = modgcd_multivariate(f, g) >>> h, cff, cfg (z, x*z - y*z, x**2 + 1) >>> cff * h == f True >>> cfg * h == g True References ========== 1. [Monagan00]_ 2. [Brown71]_ See also ======== _modgcd_multivariate_p """ assert f.ring == g.ring and f.ring.domain.is_ZZ result = _trivial_gcd(f, g) if result is not None: return result ring = f.ring k = ring.ngens # divide out integer content cf, f = f.primitive() cg, g = g.primitive() ch = ring.domain.gcd(cf, cg) gamma = ring.domain.gcd(f.LC, g.LC) badprimes = ring.domain.one for i in range(k): badprimes *= ring.domain.gcd(_swap(f, i).LC, _swap(g, i).LC) degbound = [min(fdeg, gdeg) for fdeg, gdeg in zip(f.degrees(), g.degrees())] contbound = list(degbound) m = 1 p = 1 while True: p = nextprime(p) while badprimes % p == 0: p = nextprime(p) fp = f.trunc_ground(p) gp = g.trunc_ground(p) try: # monic GCD of fp, gp in Z_p[x_0, ..., x_{k-2}, y] hp = _modgcd_multivariate_p(fp, gp, p, degbound, contbound) except ModularGCDFailed: m = 1 continue if hp is None: continue hp = hp.mul_ground(gamma).trunc_ground(p) if m == 1: m = p hlastm = hp continue hm = _chinese_remainder_reconstruction_multivariate(hp, hlastm, p, m) m *= p if not hm == hlastm: hlastm = hm continue h = hm.primitive()[1] fquo, frem = f.div(h) gquo, grem = g.div(h) if not frem and not grem: if h.LC < 0: ch = -ch h = h.mul_ground(ch) cff = fquo.mul_ground(cf // ch) cfg = gquo.mul_ground(cg // ch) return h, cff, cfg def _gf_div(f, g, p): r""" Compute `\frac f g` modulo `p` for two univariate polynomials over `\mathbb Z_p`. """ ring = f.ring densequo, denserem = gf_div(f.to_dense(), g.to_dense(), p, ring.domain) return ring.from_dense(densequo), ring.from_dense(denserem) def _rational_function_reconstruction(c, p, m): r""" Reconstruct a rational function `\frac a b` in `\mathbb Z_p(t)` from .. math:: c = \frac a b \; \mathrm{mod} \, m, where `c` and `m` are polynomials in `\mathbb Z_p[t]` and `m` has positive degree. The algorithm is based on the Euclidean Algorithm. In general, `m` is not irreducible, so it is possible that `b` is not invertible modulo `m`. In that case ``None`` is returned. Parameters ========== c : PolyElement univariate polynomial in `\mathbb Z[t]` p : Integer prime number m : PolyElement modulus, not necessarily irreducible Returns ======= frac : FracElement either `\frac a b` in `\mathbb Z(t)` or ``None`` References ========== 1. [Hoeij04]_ """ ring = c.ring domain = ring.domain M = m.degree() N = M // 2 D = M - N - 1 r0, s0 = m, ring.zero r1, s1 = c, ring.one while r1.degree() > N: quo = _gf_div(r0, r1, p)[0] r0, r1 = r1, (r0 - quo*r1).trunc_ground(p) s0, s1 = s1, (s0 - quo*s1).trunc_ground(p) a, b = r1, s1 if b.degree() > D or _gf_gcd(b, m, p) != 1: return None lc = b.LC if lc != 1: lcinv = domain.invert(lc, p) a = a.mul_ground(lcinv).trunc_ground(p) b = b.mul_ground(lcinv).trunc_ground(p) field = ring.to_field() return field(a) / field(b) def _rational_reconstruction_func_coeffs(hm, p, m, ring, k): r""" Reconstruct every coefficient `c_h` of a polynomial `h` in `\mathbb Z_p(t_k)[t_1, \ldots, t_{k-1}][x, z]` from the corresponding coefficient `c_{h_m}` of a polynomial `h_m` in `\mathbb Z_p[t_1, \ldots, t_k][x, z] \cong \mathbb Z_p[t_k][t_1, \ldots, t_{k-1}][x, z]` such that .. math:: c_{h_m} = c_h \; \mathrm{mod} \, m, where `m \in \mathbb Z_p[t]`. The reconstruction is based on the Euclidean Algorithm. In general, `m` is not irreducible, so it is possible that this fails for some coefficient. In that case ``None`` is returned. Parameters ========== hm : PolyElement polynomial in `\mathbb Z[t_1, \ldots, t_k][x, z]` p : Integer prime number, modulus of `\mathbb Z_p` m : PolyElement modulus, polynomial in `\mathbb Z[t]`, not necessarily irreducible ring : PolyRing `\mathbb Z(t_k)[t_1, \ldots, t_{k-1}][x, z]`, `h` will be an element of this ring k : Integer index of the parameter `t_k` which will be reconstructed Returns ======= h : PolyElement reconstructed polynomial in `\mathbb Z(t_k)[t_1, \ldots, t_{k-1}][x, z]` or ``None`` See also ======== _rational_function_reconstruction """ h = ring.zero for monom, coeff in hm.iterterms(): if k == 0: coeffh = _rational_function_reconstruction(coeff, p, m) if not coeffh: return None else: coeffh = ring.domain.zero for mon, c in coeff.drop_to_ground(k).iterterms(): ch = _rational_function_reconstruction(c, p, m) if not ch: return None coeffh[mon] = ch h[monom] = coeffh return h def _gf_gcdex(f, g, p): r""" Extended Euclidean Algorithm for two univariate polynomials over `\mathbb Z_p`. Returns polynomials `s, t` and `h`, such that `h` is the GCD of `f` and `g` and `sf + tg = h \; \mathrm{mod} \, p`. """ ring = f.ring s, t, h = gf_gcdex(f.to_dense(), g.to_dense(), p, ring.domain) return ring.from_dense(s), ring.from_dense(t), ring.from_dense(h) def _trunc(f, minpoly, p): r""" Compute the reduced representation of a polynomial `f` in `\mathbb Z_p[z] / (\check m_{\alpha}(z))[x]` Parameters ========== f : PolyElement polynomial in `\mathbb Z[x, z]` minpoly : PolyElement polynomial `\check m_{\alpha} \in \mathbb Z[z]`, not necessarily irreducible p : Integer prime number, modulus of `\mathbb Z_p` Returns ======= ftrunc : PolyElement polynomial in `\mathbb Z[x, z]`, reduced modulo `\check m_{\alpha}(z)` and `p` """ ring = f.ring minpoly = minpoly.set_ring(ring) p_ = ring.ground_new(p) return f.trunc_ground(p).rem([minpoly, p_]).trunc_ground(p) def _euclidean_algorithm(f, g, minpoly, p): r""" Compute the monic GCD of two univariate polynomials in `\mathbb{Z}_p[z]/(\check m_{\alpha}(z))[x]` with the Euclidean Algorithm. In general, `\check m_{\alpha}(z)` is not irreducible, so it is possible that some leading coefficient is not invertible modulo `\check m_{\alpha}(z)`. In that case ``None`` is returned. Parameters ========== f, g : PolyElement polynomials in `\mathbb Z[x, z]` minpoly : PolyElement polynomial in `\mathbb Z[z]`, not necessarily irreducible p : Integer prime number, modulus of `\mathbb Z_p` Returns ======= h : PolyElement GCD of `f` and `g` in `\mathbb Z[z, x]` or ``None``, coefficients are in `\left[ -\frac{p-1} 2, \frac{p-1} 2 \right]` """ ring = f.ring f = _trunc(f, minpoly, p) g = _trunc(g, minpoly, p) while g: rem = f deg = g.degree(0) # degree in x lcinv, _, gcd = _gf_gcdex(ring.dmp_LC(g), minpoly, p) if not gcd == 1: return None while True: degrem = rem.degree(0) # degree in x if degrem < deg: break quo = (lcinv * ring.dmp_LC(rem)).set_ring(ring) rem = _trunc(rem - g.mul_monom((degrem - deg, 0))*quo, minpoly, p) f = g g = rem lcfinv = _gf_gcdex(ring.dmp_LC(f), minpoly, p)[0].set_ring(ring) return _trunc(f * lcfinv, minpoly, p) def _trial_division(f, h, minpoly, p=None): r""" Check if `h` divides `f` in `\mathbb K[t_1, \ldots, t_k][z]/(m_{\alpha}(z))`, where `\mathbb K` is either `\mathbb Q` or `\mathbb Z_p`. This algorithm is based on pseudo division and does not use any fractions. By default `\mathbb K` is `\mathbb Q`, if a prime number `p` is given, `\mathbb Z_p` is chosen instead. Parameters ========== f, h : PolyElement polynomials in `\mathbb Z[t_1, \ldots, t_k][x, z]` minpoly : PolyElement polynomial `m_{\alpha}(z)` in `\mathbb Z[t_1, \ldots, t_k][z]` p : Integer or None if `p` is given, `\mathbb K` is set to `\mathbb Z_p` instead of `\mathbb Q`, default is ``None`` Returns ======= rem : PolyElement remainder of `\frac f h` References ========== .. [1] [Hoeij02]_ """ ring = f.ring zxring = ring.clone(symbols=(ring.symbols[1], ring.symbols[0])) minpoly = minpoly.set_ring(ring) rem = f degrem = rem.degree() degh = h.degree() degm = minpoly.degree(1) lch = _LC(h).set_ring(ring) lcm = minpoly.LC while rem and degrem >= degh: # polynomial in Z[t_1, ..., t_k][z] lcrem = _LC(rem).set_ring(ring) rem = rem*lch - h.mul_monom((degrem - degh, 0))*lcrem if p: rem = rem.trunc_ground(p) degrem = rem.degree(1) while rem and degrem >= degm: # polynomial in Z[t_1, ..., t_k][x] lcrem = _LC(rem.set_ring(zxring)).set_ring(ring) rem = rem.mul_ground(lcm) - minpoly.mul_monom((0, degrem - degm))*lcrem if p: rem = rem.trunc_ground(p) degrem = rem.degree(1) degrem = rem.degree() return rem def _evaluate_ground(f, i, a): r""" Evaluate a polynomial `f` at `a` in the `i`-th variable of the ground domain. """ ring = f.ring.clone(domain=f.ring.domain.ring.drop(i)) fa = ring.zero for monom, coeff in f.iterterms(): fa[monom] = coeff.evaluate(i, a) return fa def _func_field_modgcd_p(f, g, minpoly, p): r""" Compute the GCD of two polynomials `f` and `g` in `\mathbb Z_p(t_1, \ldots, t_k)[z]/(\check m_\alpha(z))[x]`. The algorithm reduces the problem step by step by evaluating the polynomials `f` and `g` at `t_k = a` for suitable `a \in \mathbb Z_p` and then calls itself recursively to compute the GCD in `\mathbb Z_p(t_1, \ldots, t_{k-1})[z]/(\check m_\alpha(z))[x]`. If these recursive calls are successful, the GCD over `k` variables is interpolated, otherwise the algorithm returns ``None``. After interpolation, Rational Function Reconstruction is used to obtain the correct coefficients. If this fails, a new evaluation point has to be chosen, otherwise the desired polynomial is obtained by clearing denominators. The result is verified with a fraction free trial division. Parameters ========== f, g : PolyElement polynomials in `\mathbb Z[t_1, \ldots, t_k][x, z]` minpoly : PolyElement polynomial in `\mathbb Z[t_1, \ldots, t_k][z]`, not necessarily irreducible p : Integer prime number, modulus of `\mathbb Z_p` Returns ======= h : PolyElement primitive associate in `\mathbb Z[t_1, \ldots, t_k][x, z]` of the GCD of the polynomials `f` and `g` or ``None``, coefficients are in `\left[ -\frac{p-1} 2, \frac{p-1} 2 \right]` References ========== 1. [Hoeij04]_ """ ring = f.ring domain = ring.domain # Z[t_1, ..., t_k] if isinstance(domain, PolynomialRing): k = domain.ngens else: return _euclidean_algorithm(f, g, minpoly, p) if k == 1: qdomain = domain.ring.to_field() else: qdomain = domain.ring.drop_to_ground(k - 1) qdomain = qdomain.clone(domain=qdomain.domain.ring.to_field()) qring = ring.clone(domain=qdomain) # = Z(t_k)[t_1, ..., t_{k-1}][x, z] n = 1 d = 1 # polynomial in Z_p[t_1, ..., t_k][z] gamma = ring.dmp_LC(f) * ring.dmp_LC(g) # polynomial in Z_p[t_1, ..., t_k] delta = minpoly.LC evalpoints = [] heval = [] LMlist = [] points = set(range(p)) while points: a = random.sample(points, 1)[0] points.remove(a) if k == 1: test = delta.evaluate(k-1, a) % p == 0 else: test = delta.evaluate(k-1, a).trunc_ground(p) == 0 if test: continue gammaa = _evaluate_ground(gamma, k-1, a) minpolya = _evaluate_ground(minpoly, k-1, a) if gammaa.rem([minpolya, gammaa.ring(p)]) == 0: continue fa = _evaluate_ground(f, k-1, a) ga = _evaluate_ground(g, k-1, a) # polynomial in Z_p[x, t_1, ..., t_{k-1}, z]/(minpoly) ha = _func_field_modgcd_p(fa, ga, minpolya, p) if ha is None: d += 1 if d > n: return None continue if ha == 1: return ha LM = [ha.degree()] + [0]*(k-1) if k > 1: for monom, coeff in ha.iterterms(): if monom[0] == LM[0] and coeff.LM > tuple(LM[1:]): LM[1:] = coeff.LM evalpoints_a = [a] heval_a = [ha] if k == 1: m = qring.domain.get_ring().one else: m = qring.domain.domain.get_ring().one t = m.ring.gens[0] for b, hb, LMhb in zip(evalpoints, heval, LMlist): if LMhb == LM: evalpoints_a.append(b) heval_a.append(hb) m *= (t - b) m = m.trunc_ground(p) evalpoints.append(a) heval.append(ha) LMlist.append(LM) n += 1 # polynomial in Z_p[t_1, ..., t_k][x, z] h = _interpolate_multivariate(evalpoints_a, heval_a, ring, k-1, p, ground=True) # polynomial in Z_p(t_k)[t_1, ..., t_{k-1}][x, z] h = _rational_reconstruction_func_coeffs(h, p, m, qring, k-1) if h is None: continue if k == 1: dom = qring.domain.field den = dom.ring.one for coeff in h.itercoeffs(): den = dom.ring.from_dense(gf_lcm(den.to_dense(), coeff.denom.to_dense(), p, dom.domain)) else: dom = qring.domain.domain.field den = dom.ring.one for coeff in h.itercoeffs(): for c in coeff.itercoeffs(): den = dom.ring.from_dense(gf_lcm(den.to_dense(), c.denom.to_dense(), p, dom.domain)) den = qring.domain_new(den.trunc_ground(p)) h = ring(h.mul_ground(den).as_expr()).trunc_ground(p) if not _trial_division(f, h, minpoly, p) and not _trial_division(g, h, minpoly, p): return h return None def _integer_rational_reconstruction(c, m, domain): r""" Reconstruct a rational number `\frac a b` from .. math:: c = \frac a b \; \mathrm{mod} \, m, where `c` and `m` are integers. The algorithm is based on the Euclidean Algorithm. In general, `m` is not a prime number, so it is possible that `b` is not invertible modulo `m`. In that case ``None`` is returned. Parameters ========== c : Integer `c = \frac a b \; \mathrm{mod} \, m` m : Integer modulus, not necessarily prime domain : IntegerRing `a, b, c` are elements of ``domain`` Returns ======= frac : Rational either `\frac a b` in `\mathbb Q` or ``None`` References ========== 1. [Wang81]_ """ if c < 0: c += m r0, s0 = m, domain.zero r1, s1 = c, domain.one bound = sqrt(m / 2) # still correct if replaced by ZZ.sqrt(m // 2) ? while r1 >= bound: quo = r0 // r1 r0, r1 = r1, r0 - quo*r1 s0, s1 = s1, s0 - quo*s1 if abs(s1) >= bound: return None if s1 < 0: a, b = -r1, -s1 elif s1 > 0: a, b = r1, s1 else: return None field = domain.get_field() return field(a) / field(b) def _rational_reconstruction_int_coeffs(hm, m, ring): r""" Reconstruct every rational coefficient `c_h` of a polynomial `h` in `\mathbb Q[t_1, \ldots, t_k][x, z]` from the corresponding integer coefficient `c_{h_m}` of a polynomial `h_m` in `\mathbb Z[t_1, \ldots, t_k][x, z]` such that .. math:: c_{h_m} = c_h \; \mathrm{mod} \, m, where `m \in \mathbb Z`. The reconstruction is based on the Euclidean Algorithm. In general, `m` is not a prime number, so it is possible that this fails for some coefficient. In that case ``None`` is returned. Parameters ========== hm : PolyElement polynomial in `\mathbb Z[t_1, \ldots, t_k][x, z]` m : Integer modulus, not necessarily prime ring : PolyRing `\mathbb Q[t_1, \ldots, t_k][x, z]`, `h` will be an element of this ring Returns ======= h : PolyElement reconstructed polynomial in `\mathbb Q[t_1, \ldots, t_k][x, z]` or ``None`` See also ======== _integer_rational_reconstruction """ h = ring.zero if isinstance(ring.domain, PolynomialRing): reconstruction = _rational_reconstruction_int_coeffs domain = ring.domain.ring else: reconstruction = _integer_rational_reconstruction domain = hm.ring.domain for monom, coeff in hm.iterterms(): coeffh = reconstruction(coeff, m, domain) if not coeffh: return None h[monom] = coeffh return h def _func_field_modgcd_m(f, g, minpoly): r""" Compute the GCD of two polynomials in `\mathbb Q(t_1, \ldots, t_k)[z]/(m_{\alpha}(z))[x]` using a modular algorithm. The algorithm computes the GCD of two polynomials `f` and `g` by calculating the GCD in `\mathbb Z_p(t_1, \ldots, t_k)[z] / (\check m_{\alpha}(z))[x]` for suitable primes `p` and the primitive associate `\check m_{\alpha}(z)` of `m_{\alpha}(z)`. Then the coefficients are reconstructed with the Chinese Remainder Theorem and Rational Reconstruction. To compute the GCD over `\mathbb Z_p(t_1, \ldots, t_k)[z] / (\check m_{\alpha})[x]`, the recursive subroutine ``_func_field_modgcd_p`` is used. To verify the result in `\mathbb Q(t_1, \ldots, t_k)[z] / (m_{\alpha}(z))[x]`, a fraction free trial division is used. Parameters ========== f, g : PolyElement polynomials in `\mathbb Z[t_1, \ldots, t_k][x, z]` minpoly : PolyElement irreducible polynomial in `\mathbb Z[t_1, \ldots, t_k][z]` Returns ======= h : PolyElement the primitive associate in `\mathbb Z[t_1, \ldots, t_k][x, z]` of the GCD of `f` and `g` Examples ======== >>> from sympy.polys.modulargcd import _func_field_modgcd_m >>> from sympy.polys import ring, ZZ >>> R, x, z = ring('x, z', ZZ) >>> minpoly = (z**2 - 2).drop(0) >>> f = x**2 + 2*x*z + 2 >>> g = x + z >>> _func_field_modgcd_m(f, g, minpoly) x + z >>> D, t = ring('t', ZZ) >>> R, x, z = ring('x, z', D) >>> minpoly = (z**2-3).drop(0) >>> f = x**2 + (t + 1)*x*z + 3*t >>> g = x*z + 3*t >>> _func_field_modgcd_m(f, g, minpoly) x + t*z References ========== 1. [Hoeij04]_ See also ======== _func_field_modgcd_p """ ring = f.ring domain = ring.domain if isinstance(domain, PolynomialRing): k = domain.ngens QQdomain = domain.ring.clone(domain=domain.domain.get_field()) QQring = ring.clone(domain=QQdomain) else: k = 0 QQring = ring.clone(domain=ring.domain.get_field()) cf, f = f.primitive() cg, g = g.primitive() # polynomial in Z[t_1, ..., t_k][z] gamma = ring.dmp_LC(f) * ring.dmp_LC(g) # polynomial in Z[t_1, ..., t_k] delta = minpoly.LC p = 1 primes = [] hplist = [] LMlist = [] while True: p = nextprime(p) if gamma.trunc_ground(p) == 0: continue if k == 0: test = (delta % p == 0) else: test = (delta.trunc_ground(p) == 0) if test: continue fp = f.trunc_ground(p) gp = g.trunc_ground(p) minpolyp = minpoly.trunc_ground(p) hp = _func_field_modgcd_p(fp, gp, minpolyp, p) if hp is None: continue if hp == 1: return ring.one LM = [hp.degree()] + [0]*k if k > 0: for monom, coeff in hp.iterterms(): if monom[0] == LM[0] and coeff.LM > tuple(LM[1:]): LM[1:] = coeff.LM hm = hp m = p for q, hq, LMhq in zip(primes, hplist, LMlist): if LMhq == LM: hm = _chinese_remainder_reconstruction_multivariate(hq, hm, q, m) m *= q primes.append(p) hplist.append(hp) LMlist.append(LM) hm = _rational_reconstruction_int_coeffs(hm, m, QQring) if hm is None: continue if k == 0: h = hm.clear_denoms()[1] else: den = domain.domain.one for coeff in hm.itercoeffs(): den = domain.domain.lcm(den, coeff.clear_denoms()[0]) h = hm.mul_ground(den) # convert back to Z[t_1, ..., t_k][x, z] from Q[t_1, ..., t_k][x, z] h = h.set_ring(ring) h = h.primitive()[1] if not (_trial_division(f.mul_ground(cf), h, minpoly) or _trial_division(g.mul_ground(cg), h, minpoly)): return h def _to_ZZ_poly(f, ring): r""" Compute an associate of a polynomial `f \in \mathbb Q(\alpha)[x_0, \ldots, x_{n-1}]` in `\mathbb Z[x_1, \ldots, x_{n-1}][z] / (\check m_{\alpha}(z))[x_0]`, where `\check m_{\alpha}(z) \in \mathbb Z[z]` is the primitive associate of the minimal polynomial `m_{\alpha}(z)` of `\alpha` over `\mathbb Q`. Parameters ========== f : PolyElement polynomial in `\mathbb Q(\alpha)[x_0, \ldots, x_{n-1}]` ring : PolyRing `\mathbb Z[x_1, \ldots, x_{n-1}][x_0, z]` Returns ======= f_ : PolyElement associate of `f` in `\mathbb Z[x_1, \ldots, x_{n-1}][x_0, z]` """ f_ = ring.zero if isinstance(ring.domain, PolynomialRing): domain = ring.domain.domain else: domain = ring.domain den = domain.one for coeff in f.itercoeffs(): for c in coeff.rep: if c: den = domain.lcm(den, c.denominator) for monom, coeff in f.iterterms(): coeff = coeff.rep m = ring.domain.one if isinstance(ring.domain, PolynomialRing): m = m.mul_monom(monom[1:]) n = len(coeff) for i in range(n): if coeff[i]: c = domain(coeff[i] * den) * m if (monom[0], n-i-1) not in f_: f_[(monom[0], n-i-1)] = c else: f_[(monom[0], n-i-1)] += c return f_ def _to_ANP_poly(f, ring): r""" Convert a polynomial `f \in \mathbb Z[x_1, \ldots, x_{n-1}][z]/(\check m_{\alpha}(z))[x_0]` to a polynomial in `\mathbb Q(\alpha)[x_0, \ldots, x_{n-1}]`, where `\check m_{\alpha}(z) \in \mathbb Z[z]` is the primitive associate of the minimal polynomial `m_{\alpha}(z)` of `\alpha` over `\mathbb Q`. Parameters ========== f : PolyElement polynomial in `\mathbb Z[x_1, \ldots, x_{n-1}][x_0, z]` ring : PolyRing `\mathbb Q(\alpha)[x_0, \ldots, x_{n-1}]` Returns ======= f_ : PolyElement polynomial in `\mathbb Q(\alpha)[x_0, \ldots, x_{n-1}]` """ domain = ring.domain f_ = ring.zero if isinstance(f.ring.domain, PolynomialRing): for monom, coeff in f.iterterms(): for mon, coef in coeff.iterterms(): m = (monom[0],) + mon c = domain([domain.domain(coef)] + [0]*monom[1]) if m not in f_: f_[m] = c else: f_[m] += c else: for monom, coeff in f.iterterms(): m = (monom[0],) c = domain([domain.domain(coeff)] + [0]*monom[1]) if m not in f_: f_[m] = c else: f_[m] += c return f_ def _minpoly_from_dense(minpoly, ring): r""" Change representation of the minimal polynomial from ``DMP`` to ``PolyElement`` for a given ring. """ minpoly_ = ring.zero for monom, coeff in minpoly.terms(): minpoly_[monom] = ring.domain(coeff) return minpoly_ def _primitive_in_x0(f): r""" Compute the content in `x_0` and the primitive part of a polynomial `f` in `\mathbb Q(\alpha)[x_0, x_1, \ldots, x_{n-1}] \cong \mathbb Q(\alpha)[x_1, \ldots, x_{n-1}][x_0]`. """ fring = f.ring ring = fring.drop_to_ground(*range(1, fring.ngens)) dom = ring.domain.ring f_ = ring(f.as_expr()) cont = dom.zero for coeff in f_.itercoeffs(): cont = func_field_modgcd(cont, coeff)[0] if cont == dom.one: return cont, f return cont, f.quo(cont.set_ring(fring)) # TODO: add support for algebraic function fields def func_field_modgcd(f, g): r""" Compute the GCD of two polynomials `f` and `g` in `\mathbb Q(\alpha)[x_0, \ldots, x_{n-1}]` using a modular algorithm. The algorithm first computes the primitive associate `\check m_{\alpha}(z)` of the minimal polynomial `m_{\alpha}` in `\mathbb{Z}[z]` and the primitive associates of `f` and `g` in `\mathbb{Z}[x_1, \ldots, x_{n-1}][z]/(\check m_{\alpha})[x_0]`. Then it computes the GCD in `\mathbb Q(x_1, \ldots, x_{n-1})[z]/(m_{\alpha}(z))[x_0]`. This is done by calculating the GCD in `\mathbb{Z}_p(x_1, \ldots, x_{n-1})[z]/(\check m_{\alpha}(z))[x_0]` for suitable primes `p` and then reconstructing the coefficients with the Chinese Remainder Theorem and Rational Reconstuction. The GCD over `\mathbb{Z}_p(x_1, \ldots, x_{n-1})[z]/(\check m_{\alpha}(z))[x_0]` is computed with a recursive subroutine, which evaluates the polynomials at `x_{n-1} = a` for suitable evaluation points `a \in \mathbb Z_p` and then calls itself recursively until the ground domain does no longer contain any parameters. For `\mathbb{Z}_p[z]/(\check m_{\alpha}(z))[x_0]` the Euclidean Algorithm is used. The results of those recursive calls are then interpolated and Rational Function Reconstruction is used to obtain the correct coefficients. The results, both in `\mathbb Q(x_1, \ldots, x_{n-1})[z]/(m_{\alpha}(z))[x_0]` and `\mathbb{Z}_p(x_1, \ldots, x_{n-1})[z]/(\check m_{\alpha}(z))[x_0]`, are verified by a fraction free trial division. Apart from the above GCD computation some GCDs in `\mathbb Q(\alpha)[x_1, \ldots, x_{n-1}]` have to be calculated, because treating the polynomials as univariate ones can result in a spurious content of the GCD. For this ``func_field_modgcd`` is called recursively. Parameters ========== f, g : PolyElement polynomials in `\mathbb Q(\alpha)[x_0, \ldots, x_{n-1}]` Returns ======= h : PolyElement monic GCD of the polynomials `f` and `g` cff : PolyElement cofactor of `f`, i.e. `\frac f h` cfg : PolyElement cofactor of `g`, i.e. `\frac g h` Examples ======== >>> from sympy.polys.modulargcd import func_field_modgcd >>> from sympy.polys import AlgebraicField, QQ, ring >>> from sympy import sqrt >>> A = AlgebraicField(QQ, sqrt(2)) >>> R, x = ring('x', A) >>> f = x**2 - 2 >>> g = x + sqrt(2) >>> h, cff, cfg = func_field_modgcd(f, g) >>> h == x + sqrt(2) True >>> cff * h == f True >>> cfg * h == g True >>> R, x, y = ring('x, y', A) >>> f = x**2 + 2*sqrt(2)*x*y + 2*y**2 >>> g = x + sqrt(2)*y >>> h, cff, cfg = func_field_modgcd(f, g) >>> h == x + sqrt(2)*y True >>> cff * h == f True >>> cfg * h == g True >>> f = x + sqrt(2)*y >>> g = x + y >>> h, cff, cfg = func_field_modgcd(f, g) >>> h == R.one True >>> cff * h == f True >>> cfg * h == g True References ========== 1. [Hoeij04]_ """ ring = f.ring domain = ring.domain n = ring.ngens assert ring == g.ring and domain.is_Algebraic result = _trivial_gcd(f, g) if result is not None: return result z = Dummy('z') ZZring = ring.clone(symbols=ring.symbols + (z,), domain=domain.domain.get_ring()) if n == 1: f_ = _to_ZZ_poly(f, ZZring) g_ = _to_ZZ_poly(g, ZZring) minpoly = ZZring.drop(0).from_dense(domain.mod.rep) h = _func_field_modgcd_m(f_, g_, minpoly) h = _to_ANP_poly(h, ring) else: # contx0f in Q(a)[x_1, ..., x_{n-1}], f in Q(a)[x_0, ..., x_{n-1}] contx0f, f = _primitive_in_x0(f) contx0g, g = _primitive_in_x0(g) contx0h = func_field_modgcd(contx0f, contx0g)[0] ZZring_ = ZZring.drop_to_ground(*range(1, n)) f_ = _to_ZZ_poly(f, ZZring_) g_ = _to_ZZ_poly(g, ZZring_) minpoly = _minpoly_from_dense(domain.mod, ZZring_.drop(0)) h = _func_field_modgcd_m(f_, g_, minpoly) h = _to_ANP_poly(h, ring) contx0h_, h = _primitive_in_x0(h) h *= contx0h.set_ring(ring) f *= contx0f.set_ring(ring) g *= contx0g.set_ring(ring) h = h.quo_ground(h.LC) return h, f.quo(h), g.quo(h)

a55287f0cc9a3ebaab4b45b18e365118ce55519294ee6268f5ce2e14faec229b

"""High-level polynomials manipulation functions. """ from __future__ import print_function, division from sympy.core import S, Basic, Add, Mul, symbols from sympy.core.compatibility import range from sympy.functions.combinatorial.factorials import factorial from sympy.polys.polyerrors import ( PolificationFailed, ComputationFailed, MultivariatePolynomialError, OptionError) from sympy.polys.polyoptions import allowed_flags from sympy.polys.polytools import ( poly_from_expr, parallel_poly_from_expr, Poly) from sympy.polys.specialpolys import ( symmetric_poly, interpolating_poly) from sympy.utilities import numbered_symbols, take, public @public def symmetrize(F, *gens, **args): """ Rewrite a polynomial in terms of elementary symmetric polynomials. A symmetric polynomial is a multivariate polynomial that remains invariant under any variable permutation, i.e., if ``f = f(x_1, x_2, ..., x_n)``, then ``f = f(x_{i_1}, x_{i_2}, ..., x_{i_n})``, where ``(i_1, i_2, ..., i_n)`` is a permutation of ``(1, 2, ..., n)`` (an element of the group ``S_n``). Returns a tuple of symmetric polynomials ``(f1, f2, ..., fn)`` such that ``f = f1 + f2 + ... + fn``. Examples ======== >>> from sympy.polys.polyfuncs import symmetrize >>> from sympy.abc import x, y >>> symmetrize(x**2 + y**2) (-2*x*y + (x + y)**2, 0) >>> symmetrize(x**2 + y**2, formal=True) (s1**2 - 2*s2, 0, [(s1, x + y), (s2, x*y)]) >>> symmetrize(x**2 - y**2) (-2*x*y + (x + y)**2, -2*y**2) >>> symmetrize(x**2 - y**2, formal=True) (s1**2 - 2*s2, -2*y**2, [(s1, x + y), (s2, x*y)]) """ allowed_flags(args, ['formal', 'symbols']) iterable = True if not hasattr(F, '__iter__'): iterable = False F = [F] try: F, opt = parallel_poly_from_expr(F, *gens, **args) except PolificationFailed as exc: result = [] for expr in exc.exprs: if expr.is_Number: result.append((expr, S.Zero)) else: raise ComputationFailed('symmetrize', len(F), exc) else: if not iterable: result, = result if not exc.opt.formal: return result else: if iterable: return result, [] else: return result + ([],) polys, symbols = [], opt.symbols gens, dom = opt.gens, opt.domain for i in range(len(gens)): poly = symmetric_poly(i + 1, gens, polys=True) polys.append((next(symbols), poly.set_domain(dom))) indices = list(range(len(gens) - 1)) weights = list(range(len(gens), 0, -1)) result = [] for f in F: symmetric = [] if not f.is_homogeneous: symmetric.append(f.TC()) f -= f.TC() while f: _height, _monom, _coeff = -1, None, None for i, (monom, coeff) in enumerate(f.terms()): if all(monom[i] >= monom[i + 1] for i in indices): height = max([n*m for n, m in zip(weights, monom)]) if height > _height: _height, _monom, _coeff = height, monom, coeff if _height != -1: monom, coeff = _monom, _coeff else: break exponents = [] for m1, m2 in zip(monom, monom[1:] + (0,)): exponents.append(m1 - m2) term = [s**n for (s, _), n in zip(polys, exponents)] poly = [p**n for (_, p), n in zip(polys, exponents)] symmetric.append(Mul(coeff, *term)) product = poly[0].mul(coeff) for p in poly[1:]: product = product.mul(p) f -= product result.append((Add(*symmetric), f.as_expr())) polys = [(s, p.as_expr()) for s, p in polys] if not opt.formal: for i, (sym, non_sym) in enumerate(result): result[i] = (sym.subs(polys), non_sym) if not iterable: result, = result if not opt.formal: return result else: if iterable: return result, polys else: return result + (polys,) @public def horner(f, *gens, **args): """ Rewrite a polynomial in Horner form. Among other applications, evaluation of a polynomial at a point is optimal when it is applied using the Horner scheme ([1]). Examples ======== >>> from sympy.polys.polyfuncs import horner >>> from sympy.abc import x, y, a, b, c, d, e >>> horner(9*x**4 + 8*x**3 + 7*x**2 + 6*x + 5) x*(x*(x*(9*x + 8) + 7) + 6) + 5 >>> horner(a*x**4 + b*x**3 + c*x**2 + d*x + e) e + x*(d + x*(c + x*(a*x + b))) >>> f = 4*x**2*y**2 + 2*x**2*y + 2*x*y**2 + x*y >>> horner(f, wrt=x) x*(x*y*(4*y + 2) + y*(2*y + 1)) >>> horner(f, wrt=y) y*(x*y*(4*x + 2) + x*(2*x + 1)) References ========== [1] - https://en.wikipedia.org/wiki/Horner_scheme """ allowed_flags(args, []) try: F, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: return exc.expr form, gen = S.Zero, F.gen if F.is_univariate: for coeff in F.all_coeffs(): form = form*gen + coeff else: F, gens = Poly(F, gen), gens[1:] for coeff in F.all_coeffs(): form = form*gen + horner(coeff, *gens, **args) return form @public def interpolate(data, x): """ Construct an interpolating polynomial for the data points. Examples ======== >>> from sympy.polys.polyfuncs import interpolate >>> from sympy.abc import x A list is interpreted as though it were paired with a range starting from 1: >>> interpolate([1, 4, 9, 16], x) x**2 This can be made explicit by giving a list of coordinates: >>> interpolate([(1, 1), (2, 4), (3, 9)], x) x**2 The (x, y) coordinates can also be given as keys and values of a dictionary (and the points need not be equispaced): >>> interpolate([(-1, 2), (1, 2), (2, 5)], x) x**2 + 1 >>> interpolate({-1: 2, 1: 2, 2: 5}, x) x**2 + 1 """ n = len(data) poly = None if isinstance(data, dict): X, Y = list(zip(*data.items())) poly = interpolating_poly(n, x, X, Y) else: if isinstance(data[0], tuple): X, Y = list(zip(*data)) poly = interpolating_poly(n, x, X, Y) else: Y = list(data) numert = Mul(*[(x - i) for i in range(1, n + 1)]) denom = -factorial(n - 1) if n%2 == 0 else factorial(n - 1) coeffs = [] for i in range(1, n + 1): coeffs.append(numert/(x - i)/denom) denom = denom/(i - n)*i poly = Add(*[coeff*y for coeff, y in zip(coeffs, Y)]) return poly.expand() @public def rational_interpolate(data, degnum, X=symbols('x')): """ Returns a rational interpolation, where the data points are element of any integral domain. The first argument contains the data (as a list of coordinates). The ``degnum`` argument is the degree in the numerator of the rational function. Setting it too high will decrease the maximal degree in the denominator for the same amount of data. Examples ======== >>> from sympy.polys.polyfuncs import rational_interpolate >>> data = [(1, -210), (2, -35), (3, 105), (4, 231), (5, 350), (6, 465)] >>> rational_interpolate(data, 2) (105*x**2 - 525)/(x + 1) Values do not need to be integers: >>> from sympy import sympify >>> x = [1, 2, 3, 4, 5, 6] >>> y = sympify("[-1, 0, 2, 22/5, 7, 68/7]") >>> rational_interpolate(zip(x, y), 2) (3*x**2 - 7*x + 2)/(x + 1) The symbol for the variable can be changed if needed: >>> from sympy import symbols >>> z = symbols('z') >>> rational_interpolate(data, 2, X=z) (105*z**2 - 525)/(z + 1) References ========== .. [1] Algorithm is adapted from: http://axiom-wiki.newsynthesis.org/RationalInterpolation """ from sympy.matrices.dense import ones xdata, ydata = list(zip(*data)) k = len(xdata) - degnum - 1 if k < 0: raise OptionError("Too few values for the required degree.") c = ones(degnum + k + 1, degnum + k + 2) for j in range(max(degnum, k)): for i in range(degnum + k + 1): c[i, j + 1] = c[i, j]*xdata[i] for j in range(k + 1): for i in range(degnum + k + 1): c[i, degnum + k + 1 - j] = -c[i, k - j]*ydata[i] r = c.nullspace()[0] return (sum(r[i] * X**i for i in range(degnum + 1)) / sum(r[i + degnum + 1] * X**i for i in range(k + 1))) @public def viete(f, roots=None, *gens, **args): """ Generate Viete's formulas for ``f``. Examples ======== >>> from sympy.polys.polyfuncs import viete >>> from sympy import symbols >>> x, a, b, c, r1, r2 = symbols('x,a:c,r1:3') >>> viete(a*x**2 + b*x + c, [r1, r2], x) [(r1 + r2, -b/a), (r1*r2, c/a)] """ allowed_flags(args, []) if isinstance(roots, Basic): gens, roots = (roots,) + gens, None try: f, opt = poly_from_expr(f, *gens, **args) except PolificationFailed as exc: raise ComputationFailed('viete', 1, exc) if f.is_multivariate: raise MultivariatePolynomialError( "multivariate polynomials are not allowed") n = f.degree() if n < 1: raise ValueError( "can't derive Viete's formulas for a constant polynomial") if roots is None: roots = numbered_symbols('r', start=1) roots = take(roots, n) if n != len(roots): raise ValueError("required %s roots, got %s" % (n, len(roots))) lc, coeffs = f.LC(), f.all_coeffs() result, sign = [], -1 for i, coeff in enumerate(coeffs[1:]): poly = symmetric_poly(i + 1, roots) coeff = sign*(coeff/lc) result.append((poly, coeff)) sign = -sign return result

425e7dedeab507eb79b243037069615d94c3bd3d00c86ea6b767a0696cfeaaff

"""Heuristic polynomial GCD algorithm (HEUGCD). """ from __future__ import print_function, division from sympy.core.compatibility import range from .polyerrors import HeuristicGCDFailed HEU_GCD_MAX = 6 def heugcd(f, g): """ Heuristic polynomial GCD in ``Z[X]``. Given univariate polynomials ``f`` and ``g`` in ``Z[X]``, returns their GCD and cofactors, i.e. polynomials ``h``, ``cff`` and ``cfg`` such that:: h = gcd(f, g), cff = quo(f, h) and cfg = quo(g, h) The algorithm is purely heuristic which means it may fail to compute the GCD. This will be signaled by raising an exception. In this case you will need to switch to another GCD method. The algorithm computes the polynomial GCD by evaluating polynomials ``f`` and ``g`` at certain points and computing (fast) integer GCD of those evaluations. The polynomial GCD is recovered from the integer image by interpolation. The evaluation process reduces f and g variable by variable into a large integer. The final step is to verify if the interpolated polynomial is the correct GCD. This gives cofactors of the input polynomials as a side effect. Examples ======== >>> from sympy.polys.heuristicgcd import heugcd >>> from sympy.polys import ring, ZZ >>> R, x,y, = ring("x,y", ZZ) >>> f = x**2 + 2*x*y + y**2 >>> g = x**2 + x*y >>> h, cff, cfg = heugcd(f, g) >>> h, cff, cfg (x + y, x + y, x) >>> cff*h == f True >>> cfg*h == g True References ========== .. [1] [Liao95]_ """ assert f.ring == g.ring and f.ring.domain.is_ZZ ring = f.ring x0 = ring.gens[0] domain = ring.domain gcd, f, g = f.extract_ground(g) f_norm = f.max_norm() g_norm = g.max_norm() B = domain(2*min(f_norm, g_norm) + 29) x = max(min(B, 99*domain.sqrt(B)), 2*min(f_norm // abs(f.LC), g_norm // abs(g.LC)) + 2) for i in range(0, HEU_GCD_MAX): ff = f.evaluate(x0, x) gg = g.evaluate(x0, x) if ff and gg: if ring.ngens == 1: h, cff, cfg = domain.cofactors(ff, gg) else: h, cff, cfg = heugcd(ff, gg) h = _gcd_interpolate(h, x, ring) h = h.primitive()[1] cff_, r = f.div(h) if not r: cfg_, r = g.div(h) if not r: h = h.mul_ground(gcd) return h, cff_, cfg_ cff = _gcd_interpolate(cff, x, ring) h, r = f.div(cff) if not r: cfg_, r = g.div(h) if not r: h = h.mul_ground(gcd) return h, cff, cfg_ cfg = _gcd_interpolate(cfg, x, ring) h, r = g.div(cfg) if not r: cff_, r = f.div(h) if not r: h = h.mul_ground(gcd) return h, cff_, cfg x = 73794*x * domain.sqrt(domain.sqrt(x)) // 27011 raise HeuristicGCDFailed('no luck') def _gcd_interpolate(h, x, ring): """Interpolate polynomial GCD from integer GCD. """ f, i = ring.zero, 0 # TODO: don't expose poly repr implementation details if ring.ngens == 1: while h: g = h % x if g > x // 2: g -= x h = (h - g) // x # f += X**i*g if g: f[(i,)] = g i += 1 else: while h: g = h.trunc_ground(x) h = (h - g).quo_ground(x) # f += X**i*g if g: for monom, coeff in g.iterterms(): f[(i,) + monom] = coeff i += 1 if f.LC < 0: return -f else: return f

b7598c0a743c419febb9a1e855976746833134875f6ad86c9445248454135ecd

"""Tools and arithmetics for monomials of distributed polynomials. """ from __future__ import print_function, division from itertools import combinations_with_replacement, product from textwrap import dedent from sympy.core import Mul, S, Tuple, sympify from sympy.core.compatibility import exec_, iterable, range from sympy.polys.polyerrors import ExactQuotientFailed from sympy.polys.polyutils import PicklableWithSlots, dict_from_expr from sympy.utilities import public @public def itermonomials(variables, max_degree, min_degree = 0): r""" Generate a set of monomials of the degree greater than or equal to `min_degree` and less than or equal to `max_degree`. Given a set of variables `V` and a min_degree `N` and a max_degree `M` generate a set of monomials of degree less than or equal to `N` and greater than or equal to `M`. The total number of monomials in commutative variables is huge and is given by the following formula if `M = 0`: .. math:: \frac{(\#V + N)!}{\#V! N!} For example if we would like to generate a dense polynomial of a total degree `N = 50` and `M = 0`, which is the worst case, in 5 variables, assuming that exponents and all of coefficients are 32-bit long and stored in an array we would need almost 80 GiB of memory! Fortunately most polynomials, that we will encounter, are sparse. Examples ======== Consider monomials in commutative variables `x` and `y` and non-commutative variables `a` and `b`:: >>> from sympy import symbols >>> from sympy.polys.monomials import itermonomials >>> from sympy.polys.orderings import monomial_key >>> from sympy.abc import x, y >>> sorted(itermonomials([x, y], 2), key=monomial_key('grlex', [y, x])) [1, x, y, x**2, x*y, y**2] >>> sorted(itermonomials([x, y], 3), key=monomial_key('grlex', [y, x])) [1, x, y, x**2, x*y, y**2, x**3, x**2*y, x*y**2, y**3] >>> a, b = symbols('a, b', commutative=False) >>> itermonomials([a, b, x], 2) {1, a, a**2, b, b**2, x, x**2, a*b, b*a, x*a, x*b} >>> sorted(itermonomials([x, y], 2, 1), key=monomial_key('grlex', [y, x])) [x, y, x**2, x*y, y**2] """ if max_degree < 0 or min_degree > max_degree: return set() if not variables or max_degree == 0: return {S(1)} # Force to list in case of passed tuple or other incompatible collection variables = list(variables) + [S(1)] if all(variable.is_commutative for variable in variables): monomials_list_comm = [] for item in combinations_with_replacement(variables, max_degree): powers = dict() for variable in variables: powers[variable] = 0 for variable in item: if variable != 1: powers[variable] += 1 if max(powers.values()) >= min_degree: monomials_list_comm.append(Mul(*item)) return set(monomials_list_comm) else: monomials_list_non_comm = [] for item in product(variables, repeat=max_degree): powers = dict() for variable in variables: powers[variable] = 0 for variable in item: if variable != 1: powers[variable] += 1 if max(powers.values()) >= min_degree: monomials_list_non_comm.append(Mul(*item)) return set(monomials_list_non_comm) def monomial_count(V, N): r""" Computes the number of monomials. The number of monomials is given by the following formula: .. math:: \frac{(\#V + N)!}{\#V! N!} where `N` is a total degree and `V` is a set of variables. Examples ======== >>> from sympy.polys.monomials import itermonomials, monomial_count >>> from sympy.polys.orderings import monomial_key >>> from sympy.abc import x, y >>> monomial_count(2, 2) 6 >>> M = itermonomials([x, y], 2) >>> sorted(M, key=monomial_key('grlex', [y, x])) [1, x, y, x**2, x*y, y**2] >>> len(M) 6 """ from sympy import factorial return factorial(V + N) / factorial(V) / factorial(N) def monomial_mul(A, B): """ Multiplication of tuples representing monomials. Examples ======== Lets multiply `x**3*y**4*z` with `x*y**2`:: >>> from sympy.polys.monomials import monomial_mul >>> monomial_mul((3, 4, 1), (1, 2, 0)) (4, 6, 1) which gives `x**4*y**5*z`. """ return tuple([ a + b for a, b in zip(A, B) ]) def monomial_div(A, B): """ Division of tuples representing monomials. Examples ======== Lets divide `x**3*y**4*z` by `x*y**2`:: >>> from sympy.polys.monomials import monomial_div >>> monomial_div((3, 4, 1), (1, 2, 0)) (2, 2, 1) which gives `x**2*y**2*z`. However:: >>> monomial_div((3, 4, 1), (1, 2, 2)) is None True `x*y**2*z**2` does not divide `x**3*y**4*z`. """ C = monomial_ldiv(A, B) if all(c >= 0 for c in C): return tuple(C) else: return None def monomial_ldiv(A, B): """ Division of tuples representing monomials. Examples ======== Lets divide `x**3*y**4*z` by `x*y**2`:: >>> from sympy.polys.monomials import monomial_ldiv >>> monomial_ldiv((3, 4, 1), (1, 2, 0)) (2, 2, 1) which gives `x**2*y**2*z`. >>> monomial_ldiv((3, 4, 1), (1, 2, 2)) (2, 2, -1) which gives `x**2*y**2*z**-1`. """ return tuple([ a - b for a, b in zip(A, B) ]) def monomial_pow(A, n): """Return the n-th pow of the monomial. """ return tuple([ a*n for a in A ]) def monomial_gcd(A, B): """ Greatest common divisor of tuples representing monomials. Examples ======== Lets compute GCD of `x*y**4*z` and `x**3*y**2`:: >>> from sympy.polys.monomials import monomial_gcd >>> monomial_gcd((1, 4, 1), (3, 2, 0)) (1, 2, 0) which gives `x*y**2`. """ return tuple([ min(a, b) for a, b in zip(A, B) ]) def monomial_lcm(A, B): """ Least common multiple of tuples representing monomials. Examples ======== Lets compute LCM of `x*y**4*z` and `x**3*y**2`:: >>> from sympy.polys.monomials import monomial_lcm >>> monomial_lcm((1, 4, 1), (3, 2, 0)) (3, 4, 1) which gives `x**3*y**4*z`. """ return tuple([ max(a, b) for a, b in zip(A, B) ]) def monomial_divides(A, B): """ Does there exist a monomial X such that XA == B? Examples ======== >>> from sympy.polys.monomials import monomial_divides >>> monomial_divides((1, 2), (3, 4)) True >>> monomial_divides((1, 2), (0, 2)) False """ return all(a <= b for a, b in zip(A, B)) def monomial_max(*monoms): """ Returns maximal degree for each variable in a set of monomials. Examples ======== Consider monomials `x**3*y**4*z**5`, `y**5*z` and `x**6*y**3*z**9`. We wish to find out what is the maximal degree for each of `x`, `y` and `z` variables:: >>> from sympy.polys.monomials import monomial_max >>> monomial_max((3,4,5), (0,5,1), (6,3,9)) (6, 5, 9) """ M = list(monoms[0]) for N in monoms[1:]: for i, n in enumerate(N): M[i] = max(M[i], n) return tuple(M) def monomial_min(*monoms): """ Returns minimal degree for each variable in a set of monomials. Examples ======== Consider monomials `x**3*y**4*z**5`, `y**5*z` and `x**6*y**3*z**9`. We wish to find out what is the minimal degree for each of `x`, `y` and `z` variables:: >>> from sympy.polys.monomials import monomial_min >>> monomial_min((3,4,5), (0,5,1), (6,3,9)) (0, 3, 1) """ M = list(monoms[0]) for N in monoms[1:]: for i, n in enumerate(N): M[i] = min(M[i], n) return tuple(M) def monomial_deg(M): """ Returns the total degree of a monomial. Examples ======== The total degree of `xy^2` is 3: >>> from sympy.polys.monomials import monomial_deg >>> monomial_deg((1, 2)) 3 """ return sum(M) def term_div(a, b, domain): """Division of two terms in over a ring/field. """ a_lm, a_lc = a b_lm, b_lc = b monom = monomial_div(a_lm, b_lm) if domain.is_Field: if monom is not None: return monom, domain.quo(a_lc, b_lc) else: return None else: if not (monom is None or a_lc % b_lc): return monom, domain.quo(a_lc, b_lc) else: return None class MonomialOps(object): """Code generator of fast monomial arithmetic functions. """ def __init__(self, ngens): self.ngens = ngens def _build(self, code, name): ns = {} exec_(code, ns) return ns[name] def _vars(self, name): return [ "%s%s" % (name, i) for i in range(self.ngens) ] def mul(self): name = "monomial_mul" template = dedent("""\ def %(name)s(A, B): (%(A)s,) = A (%(B)s,) = B return (%(AB)s,) """) A = self._vars("a") B = self._vars("b") AB = [ "%s + %s" % (a, b) for a, b in zip(A, B) ] code = template % dict(name=name, A=", ".join(A), B=", ".join(B), AB=", ".join(AB)) return self._build(code, name) def pow(self): name = "monomial_pow" template = dedent("""\ def %(name)s(A, k): (%(A)s,) = A return (%(Ak)s,) """) A = self._vars("a") Ak = [ "%s*k" % a for a in A ] code = template % dict(name=name, A=", ".join(A), Ak=", ".join(Ak)) return self._build(code, name) def mulpow(self): name = "monomial_mulpow" template = dedent("""\ def %(name)s(A, B, k): (%(A)s,) = A (%(B)s,) = B return (%(ABk)s,) """) A = self._vars("a") B = self._vars("b") ABk = [ "%s + %s*k" % (a, b) for a, b in zip(A, B) ] code = template % dict(name=name, A=", ".join(A), B=", ".join(B), ABk=", ".join(ABk)) return self._build(code, name) def ldiv(self): name = "monomial_ldiv" template = dedent("""\ def %(name)s(A, B): (%(A)s,) = A (%(B)s,) = B return (%(AB)s,) """) A = self._vars("a") B = self._vars("b") AB = [ "%s - %s" % (a, b) for a, b in zip(A, B) ] code = template % dict(name=name, A=", ".join(A), B=", ".join(B), AB=", ".join(AB)) return self._build(code, name) def div(self): name = "monomial_div" template = dedent("""\ def %(name)s(A, B): (%(A)s,) = A (%(B)s,) = B %(RAB)s return (%(R)s,) """) A = self._vars("a") B = self._vars("b") RAB = [ "r%(i)s = a%(i)s - b%(i)s\n if r%(i)s < 0: return None" % dict(i=i) for i in range(self.ngens) ] R = self._vars("r") code = template % dict(name=name, A=", ".join(A), B=", ".join(B), RAB="\n ".join(RAB), R=", ".join(R)) return self._build(code, name) def lcm(self): name = "monomial_lcm" template = dedent("""\ def %(name)s(A, B): (%(A)s,) = A (%(B)s,) = B return (%(AB)s,) """) A = self._vars("a") B = self._vars("b") AB = [ "%s if %s >= %s else %s" % (a, a, b, b) for a, b in zip(A, B) ] code = template % dict(name=name, A=", ".join(A), B=", ".join(B), AB=", ".join(AB)) return self._build(code, name) def gcd(self): name = "monomial_gcd" template = dedent("""\ def %(name)s(A, B): (%(A)s,) = A (%(B)s,) = B return (%(AB)s,) """) A = self._vars("a") B = self._vars("b") AB = [ "%s if %s <= %s else %s" % (a, a, b, b) for a, b in zip(A, B) ] code = template % dict(name=name, A=", ".join(A), B=", ".join(B), AB=", ".join(AB)) return self._build(code, name) @public class Monomial(PicklableWithSlots): """Class representing a monomial, i.e. a product of powers. """ __slots__ = ['exponents', 'gens'] def __init__(self, monom, gens=None): if not iterable(monom): rep, gens = dict_from_expr(sympify(monom), gens=gens) if len(rep) == 1 and list(rep.values())[0] == 1: monom = list(rep.keys())[0] else: raise ValueError("Expected a monomial got %s" % monom) self.exponents = tuple(map(int, monom)) self.gens = gens def rebuild(self, exponents, gens=None): return self.__class__(exponents, gens or self.gens) def __len__(self): return len(self.exponents) def __iter__(self): return iter(self.exponents) def __getitem__(self, item): return self.exponents[item] def __hash__(self): return hash((self.__class__.__name__, self.exponents, self.gens)) def __str__(self): if self.gens: return "*".join([ "%s**%s" % (gen, exp) for gen, exp in zip(self.gens, self.exponents) ]) else: return "%s(%s)" % (self.__class__.__name__, self.exponents) def as_expr(self, *gens): """Convert a monomial instance to a SymPy expression. """ gens = gens or self.gens if not gens: raise ValueError( "can't convert %s to an expression without generators" % self) return Mul(*[ gen**exp for gen, exp in zip(gens, self.exponents) ]) def __eq__(self, other): if isinstance(other, Monomial): exponents = other.exponents elif isinstance(other, (tuple, Tuple)): exponents = other else: return False return self.exponents == exponents def __ne__(self, other): return not self == other def __mul__(self, other): if isinstance(other, Monomial): exponents = other.exponents elif isinstance(other, (tuple, Tuple)): exponents = other else: return NotImplementedError return self.rebuild(monomial_mul(self.exponents, exponents)) def __div__(self, other): if isinstance(other, Monomial): exponents = other.exponents elif isinstance(other, (tuple, Tuple)): exponents = other else: return NotImplementedError result = monomial_div(self.exponents, exponents) if result is not None: return self.rebuild(result) else: raise ExactQuotientFailed(self, Monomial(other)) __floordiv__ = __truediv__ = __div__ def __pow__(self, other): n = int(other) if not n: return self.rebuild([0]*len(self)) elif n > 0: exponents = self.exponents for i in range(1, n): exponents = monomial_mul(exponents, self.exponents) return self.rebuild(exponents) else: raise ValueError("a non-negative integer expected, got %s" % other) def gcd(self, other): """Greatest common divisor of monomials. """ if isinstance(other, Monomial): exponents = other.exponents elif isinstance(other, (tuple, Tuple)): exponents = other else: raise TypeError( "an instance of Monomial class expected, got %s" % other) return self.rebuild(monomial_gcd(self.exponents, exponents)) def lcm(self, other): """Least common multiple of monomials. """ if isinstance(other, Monomial): exponents = other.exponents elif isinstance(other, (tuple, Tuple)): exponents = other else: raise TypeError( "an instance of Monomial class expected, got %s" % other) return self.rebuild(monomial_lcm(self.exponents, exponents))

1fb3a7215db8af6b10d61c255ad1888c60e3c28abb7e1ac505cb43a27514acda

"""Sparse rational function fields. """ from __future__ import print_function, division from operator import add, mul, lt, le, gt, ge from sympy.core.compatibility import is_sequence, reduce, string_types from sympy.core.expr import Expr from sympy.core.mod import Mod from sympy.core.numbers import Exp1 from sympy.core.singleton import S from sympy.core.symbol import Symbol from sympy.core.sympify import CantSympify, sympify from sympy.functions.elementary.exponential import ExpBase from sympy.polys.domains.domainelement import DomainElement from sympy.polys.domains.fractionfield import FractionField from sympy.polys.domains.polynomialring import PolynomialRing from sympy.polys.constructor import construct_domain from sympy.polys.orderings import lex from sympy.polys.polyerrors import CoercionFailed from sympy.polys.polyoptions import build_options from sympy.polys.polyutils import _parallel_dict_from_expr from sympy.polys.rings import PolyElement from sympy.printing.defaults import DefaultPrinting from sympy.utilities import public from sympy.utilities.magic import pollute @public def field(symbols, domain, order=lex): """Construct new rational function field returning (field, x1, ..., xn). """ _field = FracField(symbols, domain, order) return (_field,) + _field.gens @public def xfield(symbols, domain, order=lex): """Construct new rational function field returning (field, (x1, ..., xn)). """ _field = FracField(symbols, domain, order) return (_field, _field.gens) @public def vfield(symbols, domain, order=lex): """Construct new rational function field and inject generators into global namespace. """ _field = FracField(symbols, domain, order) pollute([ sym.name for sym in _field.symbols ], _field.gens) return _field @public def sfield(exprs, *symbols, **options): """Construct a field deriving generators and domain from options and input expressions. Parameters ========== exprs : :class:`Expr` or sequence of :class:`Expr` (sympifiable) symbols : sequence of :class:`Symbol`/:class:`Expr` options : keyword arguments understood by :class:`Options` Examples ======== >>> from sympy.core import symbols >>> from sympy.functions import exp, log >>> from sympy.polys.fields import sfield >>> x = symbols("x") >>> K, f = sfield((x*log(x) + 4*x**2)*exp(1/x + log(x)/3)/x**2) >>> K Rational function field in x, exp(1/x), log(x), x**(1/3) over ZZ with lex order >>> f (4*x**2*(exp(1/x)) + x*(exp(1/x))*(log(x)))/((x**(1/3))**5) """ single = False if not is_sequence(exprs): exprs, single = [exprs], True exprs = list(map(sympify, exprs)) opt = build_options(symbols, options) numdens = [] for expr in exprs: numdens.extend(expr.as_numer_denom()) reps, opt = _parallel_dict_from_expr(numdens, opt) if opt.domain is None: # NOTE: this is inefficient because construct_domain() automatically # performs conversion to the target domain. It shouldn't do this. coeffs = sum([list(rep.values()) for rep in reps], []) opt.domain, _ = construct_domain(coeffs, opt=opt) _field = FracField(opt.gens, opt.domain, opt.order) fracs = [] for i in range(0, len(reps), 2): fracs.append(_field(tuple(reps[i:i+2]))) if single: return (_field, fracs[0]) else: return (_field, fracs) _field_cache = {} class FracField(DefaultPrinting): """Multivariate distributed rational function field. """ def __new__(cls, symbols, domain, order=lex): from sympy.polys.rings import PolyRing ring = PolyRing(symbols, domain, order) symbols = ring.symbols ngens = ring.ngens domain = ring.domain order = ring.order _hash_tuple = (cls.__name__, symbols, ngens, domain, order) obj = _field_cache.get(_hash_tuple) if obj is None: obj = object.__new__(cls) obj._hash_tuple = _hash_tuple obj._hash = hash(_hash_tuple) obj.ring = ring obj.dtype = type("FracElement", (FracElement,), {"field": obj}) obj.symbols = symbols obj.ngens = ngens obj.domain = domain obj.order = order obj.zero = obj.dtype(ring.zero) obj.one = obj.dtype(ring.one) obj.gens = obj._gens() for symbol, generator in zip(obj.symbols, obj.gens): if isinstance(symbol, Symbol): name = symbol.name if not hasattr(obj, name): setattr(obj, name, generator) _field_cache[_hash_tuple] = obj return obj def _gens(self): """Return a list of polynomial generators. """ return tuple([ self.dtype(gen) for gen in self.ring.gens ]) def __getnewargs__(self): return (self.symbols, self.domain, self.order) def __hash__(self): return self._hash def __eq__(self, other): return isinstance(other, FracField) and \ (self.symbols, self.ngens, self.domain, self.order) == \ (other.symbols, other.ngens, other.domain, other.order) def __ne__(self, other): return not self == other def raw_new(self, numer, denom=None): return self.dtype(numer, denom) def new(self, numer, denom=None): if denom is None: denom = self.ring.one numer, denom = numer.cancel(denom) return self.raw_new(numer, denom) def domain_new(self, element): return self.domain.convert(element) def ground_new(self, element): try: return self.new(self.ring.ground_new(element)) except CoercionFailed: domain = self.domain if not domain.is_Field and domain.has_assoc_Field: ring = self.ring ground_field = domain.get_field() element = ground_field.convert(element) numer = ring.ground_new(ground_field.numer(element)) denom = ring.ground_new(ground_field.denom(element)) return self.raw_new(numer, denom) else: raise def field_new(self, element): if isinstance(element, FracElement): if self == element.field: return element else: raise NotImplementedError("conversion") elif isinstance(element, PolyElement): denom, numer = element.clear_denoms() numer = numer.set_ring(self.ring) denom = self.ring.ground_new(denom) return self.raw_new(numer, denom) elif isinstance(element, tuple) and len(element) == 2: numer, denom = list(map(self.ring.ring_new, element)) return self.new(numer, denom) elif isinstance(element, string_types): raise NotImplementedError("parsing") elif isinstance(element, Expr): return self.from_expr(element) else: return self.ground_new(element) __call__ = field_new def _rebuild_expr(self, expr, mapping): domain = self.domain powers = tuple((gen, gen.as_base_exp()) for gen in mapping.keys() if gen.is_Pow or isinstance(gen, ExpBase)) def _rebuild(expr): generator = mapping.get(expr) if generator is not None: return generator elif expr.is_Add: return reduce(add, list(map(_rebuild, expr.args))) elif expr.is_Mul: return reduce(mul, list(map(_rebuild, expr.args))) elif expr.is_Pow or isinstance(expr, (ExpBase, Exp1)): b, e = expr.as_base_exp() # look for bg**eg whose integer power may be b**e for gen, (bg, eg) in powers: if bg == b and Mod(e, eg) == 0: return mapping.get(gen)**int(e/eg) if e.is_Integer and e is not S.One: return _rebuild(b)**int(e) try: return domain.convert(expr) except CoercionFailed: if not domain.is_Field and domain.has_assoc_Field: return domain.get_field().convert(expr) else: raise return _rebuild(sympify(expr)) def from_expr(self, expr): mapping = dict(list(zip(self.symbols, self.gens))) try: frac = self._rebuild_expr(expr, mapping) except CoercionFailed: raise ValueError("expected an expression convertible to a rational function in %s, got %s" % (self, expr)) else: return self.field_new(frac) def to_domain(self): return FractionField(self) def to_ring(self): from sympy.polys.rings import PolyRing return PolyRing(self.symbols, self.domain, self.order) class FracElement(DomainElement, DefaultPrinting, CantSympify): """Element of multivariate distributed rational function field. """ def __init__(self, numer, denom=None): if denom is None: denom = self.field.ring.one elif not denom: raise ZeroDivisionError("zero denominator") self.numer = numer self.denom = denom def raw_new(f, numer, denom): return f.__class__(numer, denom) def new(f, numer, denom): return f.raw_new(*numer.cancel(denom)) def to_poly(f): if f.denom != 1: raise ValueError("f.denom should be 1") return f.numer def parent(self): return self.field.to_domain() def __getnewargs__(self): return (self.field, self.numer, self.denom) _hash = None def __hash__(self): _hash = self._hash if _hash is None: self._hash = _hash = hash((self.field, self.numer, self.denom)) return _hash def copy(self): return self.raw_new(self.numer.copy(), self.denom.copy()) def set_field(self, new_field): if self.field == new_field: return self else: new_ring = new_field.ring numer = self.numer.set_ring(new_ring) denom = self.denom.set_ring(new_ring) return new_field.new(numer, denom) def as_expr(self, *symbols): return self.numer.as_expr(*symbols)/self.denom.as_expr(*symbols) def __eq__(f, g): if isinstance(g, FracElement) and f.field == g.field: return f.numer == g.numer and f.denom == g.denom else: return f.numer == g and f.denom == f.field.ring.one def __ne__(f, g): return not f == g def __nonzero__(f): return bool(f.numer) __bool__ = __nonzero__ def sort_key(self): return (self.denom.sort_key(), self.numer.sort_key()) def _cmp(f1, f2, op): if isinstance(f2, f1.field.dtype): return op(f1.sort_key(), f2.sort_key()) else: return NotImplemented def __lt__(f1, f2): return f1._cmp(f2, lt) def __le__(f1, f2): return f1._cmp(f2, le) def __gt__(f1, f2): return f1._cmp(f2, gt) def __ge__(f1, f2): return f1._cmp(f2, ge) def __pos__(f): """Negate all coefficients in ``f``. """ return f.raw_new(f.numer, f.denom) def __neg__(f): """Negate all coefficients in ``f``. """ return f.raw_new(-f.numer, f.denom) def _extract_ground(self, element): domain = self.field.domain try: element = domain.convert(element) except CoercionFailed: if not domain.is_Field and domain.has_assoc_Field: ground_field = domain.get_field() try: element = ground_field.convert(element) except CoercionFailed: pass else: return -1, ground_field.numer(element), ground_field.denom(element) return 0, None, None else: return 1, element, None def __add__(f, g): """Add rational functions ``f`` and ``g``. """ field = f.field if not g: return f elif not f: return g elif isinstance(g, field.dtype): if f.denom == g.denom: return f.new(f.numer + g.numer, f.denom) else: return f.new(f.numer*g.denom + f.denom*g.numer, f.denom*g.denom) elif isinstance(g, field.ring.dtype): return f.new(f.numer + f.denom*g, f.denom) else: if isinstance(g, FracElement): if isinstance(field.domain, FractionField) and field.domain.field == g.field: pass elif isinstance(g.field.domain, FractionField) and g.field.domain.field == field: return g.__radd__(f) else: return NotImplemented elif isinstance(g, PolyElement): if isinstance(field.domain, PolynomialRing) and field.domain.ring == g.ring: pass else: return g.__radd__(f) return f.__radd__(g) def __radd__(f, c): if isinstance(c, f.field.ring.dtype): return f.new(f.numer + f.denom*c, f.denom) op, g_numer, g_denom = f._extract_ground(c) if op == 1: return f.new(f.numer + f.denom*g_numer, f.denom) elif not op: return NotImplemented else: return f.new(f.numer*g_denom + f.denom*g_numer, f.denom*g_denom) def __sub__(f, g): """Subtract rational functions ``f`` and ``g``. """ field = f.field if not g: return f elif not f: return -g elif isinstance(g, field.dtype): if f.denom == g.denom: return f.new(f.numer - g.numer, f.denom) else: return f.new(f.numer*g.denom - f.denom*g.numer, f.denom*g.denom) elif isinstance(g, field.ring.dtype): return f.new(f.numer - f.denom*g, f.denom) else: if isinstance(g, FracElement): if isinstance(field.domain, FractionField) and field.domain.field == g.field: pass elif isinstance(g.field.domain, FractionField) and g.field.domain.field == field: return g.__rsub__(f) else: return NotImplemented elif isinstance(g, PolyElement): if isinstance(field.domain, PolynomialRing) and field.domain.ring == g.ring: pass else: return g.__rsub__(f) op, g_numer, g_denom = f._extract_ground(g) if op == 1: return f.new(f.numer - f.denom*g_numer, f.denom) elif not op: return NotImplemented else: return f.new(f.numer*g_denom - f.denom*g_numer, f.denom*g_denom) def __rsub__(f, c): if isinstance(c, f.field.ring.dtype): return f.new(-f.numer + f.denom*c, f.denom) op, g_numer, g_denom = f._extract_ground(c) if op == 1: return f.new(-f.numer + f.denom*g_numer, f.denom) elif not op: return NotImplemented else: return f.new(-f.numer*g_denom + f.denom*g_numer, f.denom*g_denom) def __mul__(f, g): """Multiply rational functions ``f`` and ``g``. """ field = f.field if not f or not g: return field.zero elif isinstance(g, field.dtype): return f.new(f.numer*g.numer, f.denom*g.denom) elif isinstance(g, field.ring.dtype): return f.new(f.numer*g, f.denom) else: if isinstance(g, FracElement): if isinstance(field.domain, FractionField) and field.domain.field == g.field: pass elif isinstance(g.field.domain, FractionField) and g.field.domain.field == field: return g.__rmul__(f) else: return NotImplemented elif isinstance(g, PolyElement): if isinstance(field.domain, PolynomialRing) and field.domain.ring == g.ring: pass else: return g.__rmul__(f) return f.__rmul__(g) def __rmul__(f, c): if isinstance(c, f.field.ring.dtype): return f.new(f.numer*c, f.denom) op, g_numer, g_denom = f._extract_ground(c) if op == 1: return f.new(f.numer*g_numer, f.denom) elif not op: return NotImplemented else: return f.new(f.numer*g_numer, f.denom*g_denom) def __truediv__(f, g): """Computes quotient of fractions ``f`` and ``g``. """ field = f.field if not g: raise ZeroDivisionError elif isinstance(g, field.dtype): return f.new(f.numer*g.denom, f.denom*g.numer) elif isinstance(g, field.ring.dtype): return f.new(f.numer, f.denom*g) else: if isinstance(g, FracElement): if isinstance(field.domain, FractionField) and field.domain.field == g.field: pass elif isinstance(g.field.domain, FractionField) and g.field.domain.field == field: return g.__rtruediv__(f) else: return NotImplemented elif isinstance(g, PolyElement): if isinstance(field.domain, PolynomialRing) and field.domain.ring == g.ring: pass else: return g.__rtruediv__(f) op, g_numer, g_denom = f._extract_ground(g) if op == 1: return f.new(f.numer, f.denom*g_numer) elif not op: return NotImplemented else: return f.new(f.numer*g_denom, f.denom*g_numer) __div__ = __truediv__ def __rtruediv__(f, c): if not f: raise ZeroDivisionError elif isinstance(c, f.field.ring.dtype): return f.new(f.denom*c, f.numer) op, g_numer, g_denom = f._extract_ground(c) if op == 1: return f.new(f.denom*g_numer, f.numer) elif not op: return NotImplemented else: return f.new(f.denom*g_numer, f.numer*g_denom) __rdiv__ = __rtruediv__ def __pow__(f, n): """Raise ``f`` to a non-negative power ``n``. """ if n >= 0: return f.raw_new(f.numer**n, f.denom**n) elif not f: raise ZeroDivisionError else: return f.raw_new(f.denom**-n, f.numer**-n) def diff(f, x): """Computes partial derivative in ``x``. Examples ======== >>> from sympy.polys.fields import field >>> from sympy.polys.domains import ZZ >>> _, x, y, z = field("x,y,z", ZZ) >>> ((x**2 + y)/(z + 1)).diff(x) 2*x/(z + 1) """ x = x.to_poly() return f.new(f.numer.diff(x)*f.denom - f.numer*f.denom.diff(x), f.denom**2) def __call__(f, *values): if 0 < len(values) <= f.field.ngens: return f.evaluate(list(zip(f.field.gens, values))) else: raise ValueError("expected at least 1 and at most %s values, got %s" % (f.field.ngens, len(values))) def evaluate(f, x, a=None): if isinstance(x, list) and a is None: x = [ (X.to_poly(), a) for X, a in x ] numer, denom = f.numer.evaluate(x), f.denom.evaluate(x) else: x = x.to_poly() numer, denom = f.numer.evaluate(x, a), f.denom.evaluate(x, a) field = numer.ring.to_field() return field.new(numer, denom) def subs(f, x, a=None): if isinstance(x, list) and a is None: x = [ (X.to_poly(), a) for X, a in x ] numer, denom = f.numer.subs(x), f.denom.subs(x) else: x = x.to_poly() numer, denom = f.numer.subs(x, a), f.denom.subs(x, a) return f.new(numer, denom) def compose(f, x, a=None): raise NotImplementedError

502ccb5cc4cb867dbf1a38d071db11137fd91d98e5ee35bdd50e33faeae0222e

"""Low-level linear systems solver. """ from __future__ import print_function, division from sympy.matrices import Matrix, zeros class RawMatrix(Matrix): _sympify = staticmethod(lambda x: x) def eqs_to_matrix(eqs, ring): """Transform from equations to matrix form. """ xs = ring.gens M = zeros(len(eqs), len(xs)+1, cls=RawMatrix) for j, e_j in enumerate(eqs): for i, x_i in enumerate(xs): M[j, i] = e_j.coeff(x_i) M[j, -1] = -e_j.coeff(1) return M def solve_lin_sys(eqs, ring, _raw=True): """Solve a system of linear equations. If ``_raw`` is False, the keys and values in the returned dictionary will be of type Expr (and the unit of the field will be removed from the keys) otherwise the low-level polys types will be returned, e.g. PolyElement: PythonRational. """ as_expr = not _raw assert ring.domain.is_Field # transform from equations to matrix form matrix = eqs_to_matrix(eqs, ring) # solve by row-reduction echelon, pivots = matrix.rref(iszerofunc=lambda x: not x, simplify=lambda x: x) # construct the returnable form of the solutions keys = ring.symbols if as_expr else ring.gens if pivots[-1] == len(keys): return None if len(pivots) == len(keys): sol = [] for s in echelon[:, -1]: a = ring.ground_new(s) if as_expr: a = a.as_expr() sol.append(a) sols = dict(zip(keys, sol)) else: sols = {} g = ring.gens _g = [[-i] for i in g] for i, p in enumerate(pivots): vect = RawMatrix(_g[p + 1:] + [[ring.one]]) v = (echelon[i, p + 1:]*vect)[0] if as_expr: v = v.as_expr() sols[keys[p]] = v return sols

01db79de387f18bda5af7c7c4e809b2d5e90573c6dfc629a8510af60530a65a7

"""Algorithms for partial fraction decomposition of rational functions. """ from __future__ import print_function, division from sympy.core import S, Add, sympify, Function, Lambda, Dummy from sympy.core.basic import preorder_traversal from sympy.core.compatibility import range from sympy.polys import Poly, RootSum, cancel, factor from sympy.polys.polyerrors import PolynomialError from sympy.polys.polyoptions import allowed_flags, set_defaults from sympy.polys.polytools import parallel_poly_from_expr from sympy.utilities import numbered_symbols, take, xthreaded, public @xthreaded @public def apart(f, x=None, full=False, **options): """ Compute partial fraction decomposition of a rational function. Given a rational function ``f``, computes the partial fraction decomposition of ``f``. Two algorithms are available: One is based on the undertermined coefficients method, the other is Bronstein's full partial fraction decomposition algorithm. The undetermined coefficients method (selected by ``full=False``) uses polynomial factorization (and therefore accepts the same options as factor) for the denominator. Per default it works over the rational numbers, therefore decomposition of denominators with non-rational roots (e.g. irrational, complex roots) is not supported by default (see options of factor). Bronstein's algorithm can be selected by using ``full=True`` and allows a decomposition of denominators with non-rational roots. A human-readable result can be obtained via ``doit()`` (see examples below). Examples ======== >>> from sympy.polys.partfrac import apart >>> from sympy.abc import x, y By default, using the undetermined coefficients method: >>> apart(y/(x + 2)/(x + 1), x) -y/(x + 2) + y/(x + 1) The undetermined coefficients method does not provide a result when the denominators roots are not rational: >>> apart(y/(x**2 + x + 1), x) y/(x**2 + x + 1) You can choose Bronstein's algorithm by setting ``full=True``: >>> apart(y/(x**2 + x + 1), x, full=True) RootSum(_w**2 + _w + 1, Lambda(_a, (-2*_a*y/3 - y/3)/(-_a + x))) Calling ``doit()`` yields a human-readable result: >>> apart(y/(x**2 + x + 1), x, full=True).doit() (-y/3 - 2*y*(-1/2 - sqrt(3)*I/2)/3)/(x + 1/2 + sqrt(3)*I/2) + (-y/3 - 2*y*(-1/2 + sqrt(3)*I/2)/3)/(x + 1/2 - sqrt(3)*I/2) See Also ======== apart_list, assemble_partfrac_list """ allowed_flags(options, []) f = sympify(f) if f.is_Atom: return f else: P, Q = f.as_numer_denom() _options = options.copy() options = set_defaults(options, extension=True) try: (P, Q), opt = parallel_poly_from_expr((P, Q), x, **options) except PolynomialError as msg: if f.is_commutative: raise PolynomialError(msg) # non-commutative if f.is_Mul: c, nc = f.args_cnc(split_1=False) nc = f.func(*nc) if c: c = apart(f.func._from_args(c), x=x, full=full, **_options) return c*nc else: return nc elif f.is_Add: c = [] nc = [] for i in f.args: if i.is_commutative: c.append(i) else: try: nc.append(apart(i, x=x, full=full, **_options)) except NotImplementedError: nc.append(i) return apart(f.func(*c), x=x, full=full, **_options) + f.func(*nc) else: reps = [] pot = preorder_traversal(f) next(pot) for e in pot: try: reps.append((e, apart(e, x=x, full=full, **_options))) pot.skip() # this was handled successfully except NotImplementedError: pass return f.xreplace(dict(reps)) if P.is_multivariate: fc = f.cancel() if fc != f: return apart(fc, x=x, full=full, **_options) raise NotImplementedError( "multivariate partial fraction decomposition") common, P, Q = P.cancel(Q) poly, P = P.div(Q, auto=True) P, Q = P.rat_clear_denoms(Q) if Q.degree() <= 1: partial = P/Q else: if not full: partial = apart_undetermined_coeffs(P, Q) else: partial = apart_full_decomposition(P, Q) terms = S.Zero for term in Add.make_args(partial): if term.has(RootSum): terms += term else: terms += factor(term) return common*(poly.as_expr() + terms) def apart_undetermined_coeffs(P, Q): """Partial fractions via method of undetermined coefficients. """ X = numbered_symbols(cls=Dummy) partial, symbols = [], [] _, factors = Q.factor_list() for f, k in factors: n, q = f.degree(), Q for i in range(1, k + 1): coeffs, q = take(X, n), q.quo(f) partial.append((coeffs, q, f, i)) symbols.extend(coeffs) dom = Q.get_domain().inject(*symbols) F = Poly(0, Q.gen, domain=dom) for i, (coeffs, q, f, k) in enumerate(partial): h = Poly(coeffs, Q.gen, domain=dom) partial[i] = (h, f, k) q = q.set_domain(dom) F += h*q system, result = [], S(0) for (k,), coeff in F.terms(): system.append(coeff - P.nth(k)) from sympy.solvers import solve solution = solve(system, symbols) for h, f, k in partial: h = h.as_expr().subs(solution) result += h/f.as_expr()**k return result def apart_full_decomposition(P, Q): """ Bronstein's full partial fraction decomposition algorithm. Given a univariate rational function ``f``, performing only GCD operations over the algebraic closure of the initial ground domain of definition, compute full partial fraction decomposition with fractions having linear denominators. Note that no factorization of the initial denominator of ``f`` is performed. The final decomposition is formed in terms of a sum of :class:`RootSum` instances. References ========== .. [1] [Bronstein93]_ """ return assemble_partfrac_list(apart_list(P/Q, P.gens[0])) @public def apart_list(f, x=None, dummies=None, **options): """ Compute partial fraction decomposition of a rational function and return the result in structured form. Given a rational function ``f`` compute the partial fraction decomposition of ``f``. Only Bronstein's full partial fraction decomposition algorithm is supported by this method. The return value is highly structured and perfectly suited for further algorithmic treatment rather than being human-readable. The function returns a tuple holding three elements: * The first item is the common coefficient, free of the variable `x` used for decomposition. (It is an element of the base field `K`.) * The second item is the polynomial part of the decomposition. This can be the zero polynomial. (It is an element of `K[x]`.) * The third part itself is a list of quadruples. Each quadruple has the following elements in this order: - The (not necessarily irreducible) polynomial `D` whose roots `w_i` appear in the linear denominator of a bunch of related fraction terms. (This item can also be a list of explicit roots. However, at the moment ``apart_list`` never returns a result this way, but the related ``assemble_partfrac_list`` function accepts this format as input.) - The numerator of the fraction, written as a function of the root `w` - The linear denominator of the fraction *excluding its power exponent*, written as a function of the root `w`. - The power to which the denominator has to be raised. On can always rebuild a plain expression by using the function ``assemble_partfrac_list``. Examples ======== A first example: >>> from sympy.polys.partfrac import apart_list, assemble_partfrac_list >>> from sympy.abc import x, t >>> f = (2*x**3 - 2*x) / (x**2 - 2*x + 1) >>> pfd = apart_list(f) >>> pfd (1, Poly(2*x + 4, x, domain='ZZ'), [(Poly(_w - 1, _w, domain='ZZ'), Lambda(_a, 4), Lambda(_a, -_a + x), 1)]) >>> assemble_partfrac_list(pfd) 2*x + 4 + 4/(x - 1) Second example: >>> f = (-2*x - 2*x**2) / (3*x**2 - 6*x) >>> pfd = apart_list(f) >>> pfd (-1, Poly(2/3, x, domain='QQ'), [(Poly(_w - 2, _w, domain='ZZ'), Lambda(_a, 2), Lambda(_a, -_a + x), 1)]) >>> assemble_partfrac_list(pfd) -2/3 - 2/(x - 2) Another example, showing symbolic parameters: >>> pfd = apart_list(t/(x**2 + x + t), x) >>> pfd (1, Poly(0, x, domain='ZZ[t]'), [(Poly(_w**2 + _w + t, _w, domain='ZZ[t]'), Lambda(_a, -2*_a*t/(4*t - 1) - t/(4*t - 1)), Lambda(_a, -_a + x), 1)]) >>> assemble_partfrac_list(pfd) RootSum(_w**2 + _w + t, Lambda(_a, (-2*_a*t/(4*t - 1) - t/(4*t - 1))/(-_a + x))) This example is taken from Bronstein's original paper: >>> f = 36 / (x**5 - 2*x**4 - 2*x**3 + 4*x**2 + x - 2) >>> pfd = apart_list(f) >>> pfd (1, Poly(0, x, domain='ZZ'), [(Poly(_w - 2, _w, domain='ZZ'), Lambda(_a, 4), Lambda(_a, -_a + x), 1), (Poly(_w**2 - 1, _w, domain='ZZ'), Lambda(_a, -3*_a - 6), Lambda(_a, -_a + x), 2), (Poly(_w + 1, _w, domain='ZZ'), Lambda(_a, -4), Lambda(_a, -_a + x), 1)]) >>> assemble_partfrac_list(pfd) -4/(x + 1) - 3/(x + 1)**2 - 9/(x - 1)**2 + 4/(x - 2) See also ======== apart, assemble_partfrac_list References ========== .. [1] [Bronstein93]_ """ allowed_flags(options, []) f = sympify(f) if f.is_Atom: return f else: P, Q = f.as_numer_denom() options = set_defaults(options, extension=True) (P, Q), opt = parallel_poly_from_expr((P, Q), x, **options) if P.is_multivariate: raise NotImplementedError( "multivariate partial fraction decomposition") common, P, Q = P.cancel(Q) poly, P = P.div(Q, auto=True) P, Q = P.rat_clear_denoms(Q) polypart = poly if dummies is None: def dummies(name): d = Dummy(name) while True: yield d dummies = dummies("w") rationalpart = apart_list_full_decomposition(P, Q, dummies) return (common, polypart, rationalpart) def apart_list_full_decomposition(P, Q, dummygen): """ Bronstein's full partial fraction decomposition algorithm. Given a univariate rational function ``f``, performing only GCD operations over the algebraic closure of the initial ground domain of definition, compute full partial fraction decomposition with fractions having linear denominators. Note that no factorization of the initial denominator of ``f`` is performed. The final decomposition is formed in terms of a sum of :class:`RootSum` instances. References ========== .. [1] [Bronstein93]_ """ f, x, U = P/Q, P.gen, [] u = Function('u')(x) a = Dummy('a') partial = [] for d, n in Q.sqf_list_include(all=True): b = d.as_expr() U += [ u.diff(x, n - 1) ] h = cancel(f*b**n) / u**n H, subs = [h], [] for j in range(1, n): H += [ H[-1].diff(x) / j ] for j in range(1, n + 1): subs += [ (U[j - 1], b.diff(x, j) / j) ] for j in range(0, n): P, Q = cancel(H[j]).as_numer_denom() for i in range(0, j + 1): P = P.subs(*subs[j - i]) Q = Q.subs(*subs[0]) P = Poly(P, x) Q = Poly(Q, x) G = P.gcd(d) D = d.quo(G) B, g = Q.half_gcdex(D) b = (P * B.quo(g)).rem(D) Dw = D.subs(x, next(dummygen)) numer = Lambda(a, b.as_expr().subs(x, a)) denom = Lambda(a, (x - a)) exponent = n-j partial.append((Dw, numer, denom, exponent)) return partial @public def assemble_partfrac_list(partial_list): r"""Reassemble a full partial fraction decomposition from a structured result obtained by the function ``apart_list``. Examples ======== This example is taken from Bronstein's original paper: >>> from sympy.polys.partfrac import apart_list, assemble_partfrac_list >>> from sympy.abc import x, y >>> f = 36 / (x**5 - 2*x**4 - 2*x**3 + 4*x**2 + x - 2) >>> pfd = apart_list(f) >>> pfd (1, Poly(0, x, domain='ZZ'), [(Poly(_w - 2, _w, domain='ZZ'), Lambda(_a, 4), Lambda(_a, -_a + x), 1), (Poly(_w**2 - 1, _w, domain='ZZ'), Lambda(_a, -3*_a - 6), Lambda(_a, -_a + x), 2), (Poly(_w + 1, _w, domain='ZZ'), Lambda(_a, -4), Lambda(_a, -_a + x), 1)]) >>> assemble_partfrac_list(pfd) -4/(x + 1) - 3/(x + 1)**2 - 9/(x - 1)**2 + 4/(x - 2) If we happen to know some roots we can provide them easily inside the structure: >>> pfd = apart_list(2/(x**2-2)) >>> pfd (1, Poly(0, x, domain='ZZ'), [(Poly(_w**2 - 2, _w, domain='ZZ'), Lambda(_a, _a/2), Lambda(_a, -_a + x), 1)]) >>> pfda = assemble_partfrac_list(pfd) >>> pfda RootSum(_w**2 - 2, Lambda(_a, _a/(-_a + x)))/2 >>> pfda.doit() -sqrt(2)/(2*(x + sqrt(2))) + sqrt(2)/(2*(x - sqrt(2))) >>> from sympy import Dummy, Poly, Lambda, sqrt >>> a = Dummy("a") >>> pfd = (1, Poly(0, x, domain='ZZ'), [([sqrt(2),-sqrt(2)], Lambda(a, a/2), Lambda(a, -a + x), 1)]) >>> assemble_partfrac_list(pfd) -sqrt(2)/(2*(x + sqrt(2))) + sqrt(2)/(2*(x - sqrt(2))) See Also ======== apart, apart_list """ # Common factor common = partial_list[0] # Polynomial part polypart = partial_list[1] pfd = polypart.as_expr() # Rational parts for r, nf, df, ex in partial_list[2]: if isinstance(r, Poly): # Assemble in case the roots are given implicitly by a polynomials an, nu = nf.variables, nf.expr ad, de = df.variables, df.expr # Hack to make dummies equal because Lambda created new Dummies de = de.subs(ad[0], an[0]) func = Lambda(an, nu/de**ex) pfd += RootSum(r, func, auto=False, quadratic=False) else: # Assemble in case the roots are given explicitly by a list of algebraic numbers for root in r: pfd += nf(root)/df(root)**ex return common*pfd

a017f8df533bd2a0c2fd84521f42b5c3bc5e69ba5e33a9a5dedac39e0a940350

"""Real and complex root isolation and refinement algorithms. """ from __future__ import print_function, division from sympy.core.compatibility import range from sympy.polys.densearith import ( dup_neg, dup_rshift, dup_rem) from sympy.polys.densebasic import ( dup_LC, dup_TC, dup_degree, dup_strip, dup_reverse, dup_convert, dup_terms_gcd) from sympy.polys.densetools import ( dup_clear_denoms, dup_mirror, dup_scale, dup_shift, dup_transform, dup_diff, dup_eval, dmp_eval_in, dup_sign_variations, dup_real_imag) from sympy.polys.factortools import ( dup_factor_list) from sympy.polys.polyerrors import ( RefinementFailed, DomainError) from sympy.polys.sqfreetools import ( dup_sqf_part, dup_sqf_list) def dup_sturm(f, K): """ Computes the Sturm sequence of ``f`` in ``F[x]``. Given a univariate, square-free polynomial ``f(x)`` returns the associated Sturm sequence ``f_0(x), ..., f_n(x)`` defined by:: f_0(x), f_1(x) = f(x), f'(x) f_n = -rem(f_{n-2}(x), f_{n-1}(x)) Examples ======== >>> from sympy.polys import ring, QQ >>> R, x = ring("x", QQ) >>> R.dup_sturm(x**3 - 2*x**2 + x - 3) [x**3 - 2*x**2 + x - 3, 3*x**2 - 4*x + 1, 2/9*x + 25/9, -2079/4] References ========== .. [1] [Davenport88]_ """ if not K.is_Field: raise DomainError("can't compute Sturm sequence over %s" % K) f = dup_sqf_part(f, K) sturm = [f, dup_diff(f, 1, K)] while sturm[-1]: s = dup_rem(sturm[-2], sturm[-1], K) sturm.append(dup_neg(s, K)) return sturm[:-1] def dup_root_upper_bound(f, K): """Compute the LMQ upper bound for the positive roots of `f`; LMQ (Local Max Quadratic) was developed by Akritas-Strzebonski-Vigklas. References ========== .. [1] Alkiviadis G. Akritas: "Linear and Quadratic Complexity Bounds on the Values of the Positive Roots of Polynomials" Journal of Universal Computer Science, Vol. 15, No. 3, 523-537, 2009. """ n, P = len(f), [] t = n * [K.one] if dup_LC(f, K) < 0: f = dup_neg(f, K) f = list(reversed(f)) for i in range(0, n): if f[i] >= 0: continue a, QL = K.log(-f[i], 2), [] for j in range(i + 1, n): if f[j] <= 0: continue q = t[j] + a - K.log(f[j], 2) QL.append([q // (j - i) , j]) if not QL: continue q = min(QL) t[q[1]] = t[q[1]] + 1 P.append(q[0]) if not P: return None else: return K.get_field()(2)**(max(P) + 1) def dup_root_lower_bound(f, K): """Compute the LMQ lower bound for the positive roots of `f`; LMQ (Local Max Quadratic) was developed by Akritas-Strzebonski-Vigklas. References ========== .. [1] Alkiviadis G. Akritas: "Linear and Quadratic Complexity Bounds on the Values of the Positive Roots of Polynomials" Journal of Universal Computer Science, Vol. 15, No. 3, 523-537, 2009. """ bound = dup_root_upper_bound(dup_reverse(f), K) if bound is not None: return 1/bound else: return None def _mobius_from_interval(I, field): """Convert an open interval to a Mobius transform. """ s, t = I a, c = field.numer(s), field.denom(s) b, d = field.numer(t), field.denom(t) return a, b, c, d def _mobius_to_interval(M, field): """Convert a Mobius transform to an open interval. """ a, b, c, d = M s, t = field(a, c), field(b, d) if s <= t: return (s, t) else: return (t, s) def dup_step_refine_real_root(f, M, K, fast=False): """One step of positive real root refinement algorithm. """ a, b, c, d = M if a == b and c == d: return f, (a, b, c, d) A = dup_root_lower_bound(f, K) if A is not None: A = K(int(A)) else: A = K.zero if fast and A > 16: f = dup_scale(f, A, K) a, c, A = A*a, A*c, K.one if A >= K.one: f = dup_shift(f, A, K) b, d = A*a + b, A*c + d if not dup_eval(f, K.zero, K): return f, (b, b, d, d) f, g = dup_shift(f, K.one, K), f a1, b1, c1, d1 = a, a + b, c, c + d if not dup_eval(f, K.zero, K): return f, (b1, b1, d1, d1) k = dup_sign_variations(f, K) if k == 1: a, b, c, d = a1, b1, c1, d1 else: f = dup_shift(dup_reverse(g), K.one, K) if not dup_eval(f, K.zero, K): f = dup_rshift(f, 1, K) a, b, c, d = b, a + b, d, c + d return f, (a, b, c, d) def dup_inner_refine_real_root(f, M, K, eps=None, steps=None, disjoint=None, fast=False, mobius=False): """Refine a positive root of `f` given a Mobius transform or an interval. """ F = K.get_field() if len(M) == 2: a, b, c, d = _mobius_from_interval(M, F) else: a, b, c, d = M while not c: f, (a, b, c, d) = dup_step_refine_real_root(f, (a, b, c, d), K, fast=fast) if eps is not None and steps is not None: for i in range(0, steps): if abs(F(a, c) - F(b, d)) >= eps: f, (a, b, c, d) = dup_step_refine_real_root(f, (a, b, c, d), K, fast=fast) else: break else: if eps is not None: while abs(F(a, c) - F(b, d)) >= eps: f, (a, b, c, d) = dup_step_refine_real_root(f, (a, b, c, d), K, fast=fast) if steps is not None: for i in range(0, steps): f, (a, b, c, d) = dup_step_refine_real_root(f, (a, b, c, d), K, fast=fast) if disjoint is not None: while True: u, v = _mobius_to_interval((a, b, c, d), F) if v <= disjoint or disjoint <= u: break else: f, (a, b, c, d) = dup_step_refine_real_root(f, (a, b, c, d), K, fast=fast) if not mobius: return _mobius_to_interval((a, b, c, d), F) else: return f, (a, b, c, d) def dup_outer_refine_real_root(f, s, t, K, eps=None, steps=None, disjoint=None, fast=False): """Refine a positive root of `f` given an interval `(s, t)`. """ a, b, c, d = _mobius_from_interval((s, t), K.get_field()) f = dup_transform(f, dup_strip([a, b]), dup_strip([c, d]), K) if dup_sign_variations(f, K) != 1: raise RefinementFailed("there should be exactly one root in (%s, %s) interval" % (s, t)) return dup_inner_refine_real_root(f, (a, b, c, d), K, eps=eps, steps=steps, disjoint=disjoint, fast=fast) def dup_refine_real_root(f, s, t, K, eps=None, steps=None, disjoint=None, fast=False): """Refine real root's approximating interval to the given precision. """ if K.is_QQ: (_, f), K = dup_clear_denoms(f, K, convert=True), K.get_ring() elif not K.is_ZZ: raise DomainError("real root refinement not supported over %s" % K) if s == t: return (s, t) if s > t: s, t = t, s negative = False if s < 0: if t <= 0: f, s, t, negative = dup_mirror(f, K), -t, -s, True else: raise ValueError("can't refine a real root in (%s, %s)" % (s, t)) if negative and disjoint is not None: if disjoint < 0: disjoint = -disjoint else: disjoint = None s, t = dup_outer_refine_real_root( f, s, t, K, eps=eps, steps=steps, disjoint=disjoint, fast=fast) if negative: return (-t, -s) else: return ( s, t) def dup_inner_isolate_real_roots(f, K, eps=None, fast=False): """Internal function for isolation positive roots up to given precision. References ========== 1. Alkiviadis G. Akritas and Adam W. Strzebonski: A Comparative Study of Two Real Root Isolation Methods . Nonlinear Analysis: Modelling and Control, Vol. 10, No. 4, 297-304, 2005. 2. Alkiviadis G. Akritas, Adam W. Strzebonski and Panagiotis S. Vigklas: Improving the Performance of the Continued Fractions Method Using new Bounds of Positive Roots. Nonlinear Analysis: Modelling and Control, Vol. 13, No. 3, 265-279, 2008. """ a, b, c, d = K.one, K.zero, K.zero, K.one k = dup_sign_variations(f, K) if k == 0: return [] if k == 1: roots = [dup_inner_refine_real_root( f, (a, b, c, d), K, eps=eps, fast=fast, mobius=True)] else: roots, stack = [], [(a, b, c, d, f, k)] while stack: a, b, c, d, f, k = stack.pop() A = dup_root_lower_bound(f, K) if A is not None: A = K(int(A)) else: A = K.zero if fast and A > 16: f = dup_scale(f, A, K) a, c, A = A*a, A*c, K.one if A >= K.one: f = dup_shift(f, A, K) b, d = A*a + b, A*c + d if not dup_TC(f, K): roots.append((f, (b, b, d, d))) f = dup_rshift(f, 1, K) k = dup_sign_variations(f, K) if k == 0: continue if k == 1: roots.append(dup_inner_refine_real_root( f, (a, b, c, d), K, eps=eps, fast=fast, mobius=True)) continue f1 = dup_shift(f, K.one, K) a1, b1, c1, d1, r = a, a + b, c, c + d, 0 if not dup_TC(f1, K): roots.append((f1, (b1, b1, d1, d1))) f1, r = dup_rshift(f1, 1, K), 1 k1 = dup_sign_variations(f1, K) k2 = k - k1 - r a2, b2, c2, d2 = b, a + b, d, c + d if k2 > 1: f2 = dup_shift(dup_reverse(f), K.one, K) if not dup_TC(f2, K): f2 = dup_rshift(f2, 1, K) k2 = dup_sign_variations(f2, K) else: f2 = None if k1 < k2: a1, a2, b1, b2 = a2, a1, b2, b1 c1, c2, d1, d2 = c2, c1, d2, d1 f1, f2, k1, k2 = f2, f1, k2, k1 if not k1: continue if f1 is None: f1 = dup_shift(dup_reverse(f), K.one, K) if not dup_TC(f1, K): f1 = dup_rshift(f1, 1, K) if k1 == 1: roots.append(dup_inner_refine_real_root( f1, (a1, b1, c1, d1), K, eps=eps, fast=fast, mobius=True)) else: stack.append((a1, b1, c1, d1, f1, k1)) if not k2: continue if f2 is None: f2 = dup_shift(dup_reverse(f), K.one, K) if not dup_TC(f2, K): f2 = dup_rshift(f2, 1, K) if k2 == 1: roots.append(dup_inner_refine_real_root( f2, (a2, b2, c2, d2), K, eps=eps, fast=fast, mobius=True)) else: stack.append((a2, b2, c2, d2, f2, k2)) return roots def _discard_if_outside_interval(f, M, inf, sup, K, negative, fast, mobius): """Discard an isolating interval if outside ``(inf, sup)``. """ F = K.get_field() while True: u, v = _mobius_to_interval(M, F) if negative: u, v = -v, -u if (inf is None or u >= inf) and (sup is None or v <= sup): if not mobius: return u, v else: return f, M elif (sup is not None and u > sup) or (inf is not None and v < inf): return None else: f, M = dup_step_refine_real_root(f, M, K, fast=fast) def dup_inner_isolate_positive_roots(f, K, eps=None, inf=None, sup=None, fast=False, mobius=False): """Iteratively compute disjoint positive root isolation intervals. """ if sup is not None and sup < 0: return [] roots = dup_inner_isolate_real_roots(f, K, eps=eps, fast=fast) F, results = K.get_field(), [] if inf is not None or sup is not None: for f, M in roots: result = _discard_if_outside_interval(f, M, inf, sup, K, False, fast, mobius) if result is not None: results.append(result) elif not mobius: for f, M in roots: u, v = _mobius_to_interval(M, F) results.append((u, v)) else: results = roots return results def dup_inner_isolate_negative_roots(f, K, inf=None, sup=None, eps=None, fast=False, mobius=False): """Iteratively compute disjoint negative root isolation intervals. """ if inf is not None and inf >= 0: return [] roots = dup_inner_isolate_real_roots(dup_mirror(f, K), K, eps=eps, fast=fast) F, results = K.get_field(), [] if inf is not None or sup is not None: for f, M in roots: result = _discard_if_outside_interval(f, M, inf, sup, K, True, fast, mobius) if result is not None: results.append(result) elif not mobius: for f, M in roots: u, v = _mobius_to_interval(M, F) results.append((-v, -u)) else: results = roots return results def _isolate_zero(f, K, inf, sup, basis=False, sqf=False): """Handle special case of CF algorithm when ``f`` is homogeneous. """ j, f = dup_terms_gcd(f, K) if j > 0: F = K.get_field() if (inf is None or inf <= 0) and (sup is None or 0 <= sup): if not sqf: if not basis: return [((F.zero, F.zero), j)], f else: return [((F.zero, F.zero), j, [K.one, K.zero])], f else: return [(F.zero, F.zero)], f return [], f def dup_isolate_real_roots_sqf(f, K, eps=None, inf=None, sup=None, fast=False, blackbox=False): """Isolate real roots of a square-free polynomial using the Vincent-Akritas-Strzebonski (VAS) CF approach. References ========== .. [1] Alkiviadis G. Akritas and Adam W. Strzebonski: A Comparative Study of Two Real Root Isolation Methods. Nonlinear Analysis: Modelling and Control, Vol. 10, No. 4, 297-304, 2005. .. [2] Alkiviadis G. Akritas, Adam W. Strzebonski and Panagiotis S. Vigklas: Improving the Performance of the Continued Fractions Method Using New Bounds of Positive Roots. Nonlinear Analysis: Modelling and Control, Vol. 13, No. 3, 265-279, 2008. """ if K.is_QQ: (_, f), K = dup_clear_denoms(f, K, convert=True), K.get_ring() elif not K.is_ZZ: raise DomainError("isolation of real roots not supported over %s" % K) if dup_degree(f) <= 0: return [] I_zero, f = _isolate_zero(f, K, inf, sup, basis=False, sqf=True) I_neg = dup_inner_isolate_negative_roots(f, K, eps=eps, inf=inf, sup=sup, fast=fast) I_pos = dup_inner_isolate_positive_roots(f, K, eps=eps, inf=inf, sup=sup, fast=fast) roots = sorted(I_neg + I_zero + I_pos) if not blackbox: return roots else: return [ RealInterval((a, b), f, K) for (a, b) in roots ] def dup_isolate_real_roots(f, K, eps=None, inf=None, sup=None, basis=False, fast=False): """Isolate real roots using Vincent-Akritas-Strzebonski (VAS) continued fractions approach. References ========== .. [1] Alkiviadis G. Akritas and Adam W. Strzebonski: A Comparative Study of Two Real Root Isolation Methods. Nonlinear Analysis: Modelling and Control, Vol. 10, No. 4, 297-304, 2005. .. [2] Alkiviadis G. Akritas, Adam W. Strzebonski and Panagiotis S. Vigklas: Improving the Performance of the Continued Fractions Method Using New Bounds of Positive Roots. Nonlinear Analysis: Modelling and Control, Vol. 13, No. 3, 265-279, 2008. """ if K.is_QQ: (_, f), K = dup_clear_denoms(f, K, convert=True), K.get_ring() elif not K.is_ZZ: raise DomainError("isolation of real roots not supported over %s" % K) if dup_degree(f) <= 0: return [] I_zero, f = _isolate_zero(f, K, inf, sup, basis=basis, sqf=False) _, factors = dup_sqf_list(f, K) if len(factors) == 1: ((f, k),) = factors I_neg = dup_inner_isolate_negative_roots(f, K, eps=eps, inf=inf, sup=sup, fast=fast) I_pos = dup_inner_isolate_positive_roots(f, K, eps=eps, inf=inf, sup=sup, fast=fast) I_neg = [ ((u, v), k) for u, v in I_neg ] I_pos = [ ((u, v), k) for u, v in I_pos ] else: I_neg, I_pos = _real_isolate_and_disjoin(factors, K, eps=eps, inf=inf, sup=sup, basis=basis, fast=fast) return sorted(I_neg + I_zero + I_pos) def dup_isolate_real_roots_list(polys, K, eps=None, inf=None, sup=None, strict=False, basis=False, fast=False): """Isolate real roots of a list of square-free polynomial using Vincent-Akritas-Strzebonski (VAS) CF approach. References ========== .. [1] Alkiviadis G. Akritas and Adam W. Strzebonski: A Comparative Study of Two Real Root Isolation Methods. Nonlinear Analysis: Modelling and Control, Vol. 10, No. 4, 297-304, 2005. .. [2] Alkiviadis G. Akritas, Adam W. Strzebonski and Panagiotis S. Vigklas: Improving the Performance of the Continued Fractions Method Using New Bounds of Positive Roots. Nonlinear Analysis: Modelling and Control, Vol. 13, No. 3, 265-279, 2008. """ if K.is_QQ: K, F, polys = K.get_ring(), K, polys[:] for i, p in enumerate(polys): polys[i] = dup_clear_denoms(p, F, K, convert=True)[1] elif not K.is_ZZ: raise DomainError("isolation of real roots not supported over %s" % K) zeros, factors_dict = False, {} if (inf is None or inf <= 0) and (sup is None or 0 <= sup): zeros, zero_indices = True, {} for i, p in enumerate(polys): j, p = dup_terms_gcd(p, K) if zeros and j > 0: zero_indices[i] = j for f, k in dup_factor_list(p, K)[1]: f = tuple(f) if f not in factors_dict: factors_dict[f] = {i: k} else: factors_dict[f][i] = k factors_list = [] for f, indices in factors_dict.items(): factors_list.append((list(f), indices)) I_neg, I_pos = _real_isolate_and_disjoin(factors_list, K, eps=eps, inf=inf, sup=sup, strict=strict, basis=basis, fast=fast) F = K.get_field() if not zeros or not zero_indices: I_zero = [] else: if not basis: I_zero = [((F.zero, F.zero), zero_indices)] else: I_zero = [((F.zero, F.zero), zero_indices, [K.one, K.zero])] return sorted(I_neg + I_zero + I_pos) def _disjoint_p(M, N, strict=False): """Check if Mobius transforms define disjoint intervals. """ a1, b1, c1, d1 = M a2, b2, c2, d2 = N a1d1, b1c1 = a1*d1, b1*c1 a2d2, b2c2 = a2*d2, b2*c2 if a1d1 == b1c1 and a2d2 == b2c2: return True if a1d1 > b1c1: a1, c1, b1, d1 = b1, d1, a1, c1 if a2d2 > b2c2: a2, c2, b2, d2 = b2, d2, a2, c2 if not strict: return a2*d1 >= c2*b1 or b2*c1 <= d2*a1 else: return a2*d1 > c2*b1 or b2*c1 < d2*a1 def _real_isolate_and_disjoin(factors, K, eps=None, inf=None, sup=None, strict=False, basis=False, fast=False): """Isolate real roots of a list of polynomials and disjoin intervals. """ I_pos, I_neg = [], [] for i, (f, k) in enumerate(factors): for F, M in dup_inner_isolate_positive_roots(f, K, eps=eps, inf=inf, sup=sup, fast=fast, mobius=True): I_pos.append((F, M, k, f)) for G, N in dup_inner_isolate_negative_roots(f, K, eps=eps, inf=inf, sup=sup, fast=fast, mobius=True): I_neg.append((G, N, k, f)) for i, (f, M, k, F) in enumerate(I_pos): for j, (g, N, m, G) in enumerate(I_pos[i + 1:]): while not _disjoint_p(M, N, strict=strict): f, M = dup_inner_refine_real_root(f, M, K, steps=1, fast=fast, mobius=True) g, N = dup_inner_refine_real_root(g, N, K, steps=1, fast=fast, mobius=True) I_pos[i + j + 1] = (g, N, m, G) I_pos[i] = (f, M, k, F) for i, (f, M, k, F) in enumerate(I_neg): for j, (g, N, m, G) in enumerate(I_neg[i + 1:]): while not _disjoint_p(M, N, strict=strict): f, M = dup_inner_refine_real_root(f, M, K, steps=1, fast=fast, mobius=True) g, N = dup_inner_refine_real_root(g, N, K, steps=1, fast=fast, mobius=True) I_neg[i + j + 1] = (g, N, m, G) I_neg[i] = (f, M, k, F) if strict: for i, (f, M, k, F) in enumerate(I_neg): if not M[0]: while not M[0]: f, M = dup_inner_refine_real_root(f, M, K, steps=1, fast=fast, mobius=True) I_neg[i] = (f, M, k, F) break for j, (g, N, m, G) in enumerate(I_pos): if not N[0]: while not N[0]: g, N = dup_inner_refine_real_root(g, N, K, steps=1, fast=fast, mobius=True) I_pos[j] = (g, N, m, G) break field = K.get_field() I_neg = [ (_mobius_to_interval(M, field), k, f) for (_, M, k, f) in I_neg ] I_pos = [ (_mobius_to_interval(M, field), k, f) for (_, M, k, f) in I_pos ] if not basis: I_neg = [ ((-v, -u), k) for ((u, v), k, _) in I_neg ] I_pos = [ (( u, v), k) for ((u, v), k, _) in I_pos ] else: I_neg = [ ((-v, -u), k, f) for ((u, v), k, f) in I_neg ] I_pos = [ (( u, v), k, f) for ((u, v), k, f) in I_pos ] return I_neg, I_pos def dup_count_real_roots(f, K, inf=None, sup=None): """Returns the number of distinct real roots of ``f`` in ``[inf, sup]``. """ if dup_degree(f) <= 0: return 0 if not K.is_Field: R, K = K, K.get_field() f = dup_convert(f, R, K) sturm = dup_sturm(f, K) if inf is None: signs_inf = dup_sign_variations([ dup_LC(s, K)*(-1)**dup_degree(s) for s in sturm ], K) else: signs_inf = dup_sign_variations([ dup_eval(s, inf, K) for s in sturm ], K) if sup is None: signs_sup = dup_sign_variations([ dup_LC(s, K) for s in sturm ], K) else: signs_sup = dup_sign_variations([ dup_eval(s, sup, K) for s in sturm ], K) count = abs(signs_inf - signs_sup) if inf is not None and not dup_eval(f, inf, K): count += 1 return count OO = 'OO' # Origin of (re, im) coordinate system Q1 = 'Q1' # Quadrant #1 (++): re > 0 and im > 0 Q2 = 'Q2' # Quadrant #2 (-+): re < 0 and im > 0 Q3 = 'Q3' # Quadrant #3 (--): re < 0 and im < 0 Q4 = 'Q4' # Quadrant #4 (+-): re > 0 and im < 0 A1 = 'A1' # Axis #1 (+0): re > 0 and im = 0 A2 = 'A2' # Axis #2 (0+): re = 0 and im > 0 A3 = 'A3' # Axis #3 (-0): re < 0 and im = 0 A4 = 'A4' # Axis #4 (0-): re = 0 and im < 0 _rules_simple = { # Q --> Q (same) => no change (Q1, Q1): 0, (Q2, Q2): 0, (Q3, Q3): 0, (Q4, Q4): 0, # A -- CCW --> Q => +1/4 (CCW) (A1, Q1): 1, (A2, Q2): 1, (A3, Q3): 1, (A4, Q4): 1, # A -- CW --> Q => -1/4 (CCW) (A1, Q4): 2, (A2, Q1): 2, (A3, Q2): 2, (A4, Q3): 2, # Q -- CCW --> A => +1/4 (CCW) (Q1, A2): 3, (Q2, A3): 3, (Q3, A4): 3, (Q4, A1): 3, # Q -- CW --> A => -1/4 (CCW) (Q1, A1): 4, (Q2, A2): 4, (Q3, A3): 4, (Q4, A4): 4, # Q -- CCW --> Q => +1/2 (CCW) (Q1, Q2): +5, (Q2, Q3): +5, (Q3, Q4): +5, (Q4, Q1): +5, # Q -- CW --> Q => -1/2 (CW) (Q1, Q4): -5, (Q2, Q1): -5, (Q3, Q2): -5, (Q4, Q3): -5, } _rules_ambiguous = { # A -- CCW --> Q => { +1/4 (CCW), -9/4 (CW) } (A1, OO, Q1): -1, (A2, OO, Q2): -1, (A3, OO, Q3): -1, (A4, OO, Q4): -1, # A -- CW --> Q => { -1/4 (CCW), +7/4 (CW) } (A1, OO, Q4): -2, (A2, OO, Q1): -2, (A3, OO, Q2): -2, (A4, OO, Q3): -2, # Q -- CCW --> A => { +1/4 (CCW), -9/4 (CW) } (Q1, OO, A2): -3, (Q2, OO, A3): -3, (Q3, OO, A4): -3, (Q4, OO, A1): -3, # Q -- CW --> A => { -1/4 (CCW), +7/4 (CW) } (Q1, OO, A1): -4, (Q2, OO, A2): -4, (Q3, OO, A3): -4, (Q4, OO, A4): -4, # A -- OO --> A => { +1 (CCW), -1 (CW) } (A1, A3): 7, (A2, A4): 7, (A3, A1): 7, (A4, A2): 7, (A1, OO, A3): 7, (A2, OO, A4): 7, (A3, OO, A1): 7, (A4, OO, A2): 7, # Q -- DIA --> Q => { +1 (CCW), -1 (CW) } (Q1, Q3): 8, (Q2, Q4): 8, (Q3, Q1): 8, (Q4, Q2): 8, (Q1, OO, Q3): 8, (Q2, OO, Q4): 8, (Q3, OO, Q1): 8, (Q4, OO, Q2): 8, # A --- R ---> A => { +1/2 (CCW), -3/2 (CW) } (A1, A2): 9, (A2, A3): 9, (A3, A4): 9, (A4, A1): 9, (A1, OO, A2): 9, (A2, OO, A3): 9, (A3, OO, A4): 9, (A4, OO, A1): 9, # A --- L ---> A => { +3/2 (CCW), -1/2 (CW) } (A1, A4): 10, (A2, A1): 10, (A3, A2): 10, (A4, A3): 10, (A1, OO, A4): 10, (A2, OO, A1): 10, (A3, OO, A2): 10, (A4, OO, A3): 10, # Q --- 1 ---> A => { +3/4 (CCW), -5/4 (CW) } (Q1, A3): 11, (Q2, A4): 11, (Q3, A1): 11, (Q4, A2): 11, (Q1, OO, A3): 11, (Q2, OO, A4): 11, (Q3, OO, A1): 11, (Q4, OO, A2): 11, # Q --- 2 ---> A => { +5/4 (CCW), -3/4 (CW) } (Q1, A4): 12, (Q2, A1): 12, (Q3, A2): 12, (Q4, A3): 12, (Q1, OO, A4): 12, (Q2, OO, A1): 12, (Q3, OO, A2): 12, (Q4, OO, A3): 12, # A --- 1 ---> Q => { +5/4 (CCW), -3/4 (CW) } (A1, Q3): 13, (A2, Q4): 13, (A3, Q1): 13, (A4, Q2): 13, (A1, OO, Q3): 13, (A2, OO, Q4): 13, (A3, OO, Q1): 13, (A4, OO, Q2): 13, # A --- 2 ---> Q => { +3/4 (CCW), -5/4 (CW) } (A1, Q2): 14, (A2, Q3): 14, (A3, Q4): 14, (A4, Q1): 14, (A1, OO, Q2): 14, (A2, OO, Q3): 14, (A3, OO, Q4): 14, (A4, OO, Q1): 14, # Q --> OO --> Q => { +1/2 (CCW), -3/2 (CW) } (Q1, OO, Q2): 15, (Q2, OO, Q3): 15, (Q3, OO, Q4): 15, (Q4, OO, Q1): 15, # Q --> OO --> Q => { +3/2 (CCW), -1/2 (CW) } (Q1, OO, Q4): 16, (Q2, OO, Q1): 16, (Q3, OO, Q2): 16, (Q4, OO, Q3): 16, # A --> OO --> A => { +2 (CCW), 0 (CW) } (A1, OO, A1): 17, (A2, OO, A2): 17, (A3, OO, A3): 17, (A4, OO, A4): 17, # Q --> OO --> Q => { +2 (CCW), 0 (CW) } (Q1, OO, Q1): 18, (Q2, OO, Q2): 18, (Q3, OO, Q3): 18, (Q4, OO, Q4): 18, } _values = { 0: [( 0, 1)], 1: [(+1, 4)], 2: [(-1, 4)], 3: [(+1, 4)], 4: [(-1, 4)], -1: [(+9, 4), (+1, 4)], -2: [(+7, 4), (-1, 4)], -3: [(+9, 4), (+1, 4)], -4: [(+7, 4), (-1, 4)], +5: [(+1, 2)], -5: [(-1, 2)], 7: [(+1, 1), (-1, 1)], 8: [(+1, 1), (-1, 1)], 9: [(+1, 2), (-3, 2)], 10: [(+3, 2), (-1, 2)], 11: [(+3, 4), (-5, 4)], 12: [(+5, 4), (-3, 4)], 13: [(+5, 4), (-3, 4)], 14: [(+3, 4), (-5, 4)], 15: [(+1, 2), (-3, 2)], 16: [(+3, 2), (-1, 2)], 17: [(+2, 1), ( 0, 1)], 18: [(+2, 1), ( 0, 1)], } def _classify_point(re, im): """Return the half-axis (or origin) on which (re, im) point is located. """ if not re and not im: return OO if not re: if im > 0: return A2 else: return A4 elif not im: if re > 0: return A1 else: return A3 def _intervals_to_quadrants(intervals, f1, f2, s, t, F): """Generate a sequence of extended quadrants from a list of critical points. """ if not intervals: return [] Q = [] if not f1: (a, b), _, _ = intervals[0] if a == b == s: if len(intervals) == 1: if dup_eval(f2, t, F) > 0: return [OO, A2] else: return [OO, A4] else: (a, _), _, _ = intervals[1] if dup_eval(f2, (s + a)/2, F) > 0: Q.extend([OO, A2]) f2_sgn = +1 else: Q.extend([OO, A4]) f2_sgn = -1 intervals = intervals[1:] else: if dup_eval(f2, s, F) > 0: Q.append(A2) f2_sgn = +1 else: Q.append(A4) f2_sgn = -1 for (a, _), indices, _ in intervals: Q.append(OO) if indices[1] % 2 == 1: f2_sgn = -f2_sgn if a != t: if f2_sgn > 0: Q.append(A2) else: Q.append(A4) return Q if not f2: (a, b), _, _ = intervals[0] if a == b == s: if len(intervals) == 1: if dup_eval(f1, t, F) > 0: return [OO, A1] else: return [OO, A3] else: (a, _), _, _ = intervals[1] if dup_eval(f1, (s + a)/2, F) > 0: Q.extend([OO, A1]) f1_sgn = +1 else: Q.extend([OO, A3]) f1_sgn = -1 intervals = intervals[1:] else: if dup_eval(f1, s, F) > 0: Q.append(A1) f1_sgn = +1 else: Q.append(A3) f1_sgn = -1 for (a, _), indices, _ in intervals: Q.append(OO) if indices[0] % 2 == 1: f1_sgn = -f1_sgn if a != t: if f1_sgn > 0: Q.append(A1) else: Q.append(A3) return Q re = dup_eval(f1, s, F) im = dup_eval(f2, s, F) if not re or not im: Q.append(_classify_point(re, im)) if len(intervals) == 1: re = dup_eval(f1, t, F) im = dup_eval(f2, t, F) else: (a, _), _, _ = intervals[1] re = dup_eval(f1, (s + a)/2, F) im = dup_eval(f2, (s + a)/2, F) intervals = intervals[1:] if re > 0: f1_sgn = +1 else: f1_sgn = -1 if im > 0: f2_sgn = +1 else: f2_sgn = -1 sgn = { (+1, +1): Q1, (-1, +1): Q2, (-1, -1): Q3, (+1, -1): Q4, } Q.append(sgn[(f1_sgn, f2_sgn)]) for (a, b), indices, _ in intervals: if a == b: re = dup_eval(f1, a, F) im = dup_eval(f2, a, F) cls = _classify_point(re, im) if cls is not None: Q.append(cls) if 0 in indices: if indices[0] % 2 == 1: f1_sgn = -f1_sgn if 1 in indices: if indices[1] % 2 == 1: f2_sgn = -f2_sgn if not (a == b and b == t): Q.append(sgn[(f1_sgn, f2_sgn)]) return Q def _traverse_quadrants(Q_L1, Q_L2, Q_L3, Q_L4, exclude=None): """Transform sequences of quadrants to a sequence of rules. """ if exclude is True: edges = [1, 1, 0, 0] corners = { (0, 1): 1, (1, 2): 1, (2, 3): 0, (3, 0): 1, } else: edges = [0, 0, 0, 0] corners = { (0, 1): 0, (1, 2): 0, (2, 3): 0, (3, 0): 0, } if exclude is not None and exclude is not True: exclude = set(exclude) for i, edge in enumerate(['S', 'E', 'N', 'W']): if edge in exclude: edges[i] = 1 for i, corner in enumerate(['SW', 'SE', 'NE', 'NW']): if corner in exclude: corners[((i - 1) % 4, i)] = 1 QQ, rules = [Q_L1, Q_L2, Q_L3, Q_L4], [] for i, Q in enumerate(QQ): if not Q: continue if Q[-1] == OO: Q = Q[:-1] if Q[0] == OO: j, Q = (i - 1) % 4, Q[1:] qq = (QQ[j][-2], OO, Q[0]) if qq in _rules_ambiguous: rules.append((_rules_ambiguous[qq], corners[(j, i)])) else: raise NotImplementedError("3 element rule (corner): " + str(qq)) q1, k = Q[0], 1 while k < len(Q): q2, k = Q[k], k + 1 if q2 != OO: qq = (q1, q2) if qq in _rules_simple: rules.append((_rules_simple[qq], 0)) elif qq in _rules_ambiguous: rules.append((_rules_ambiguous[qq], edges[i])) else: raise NotImplementedError("2 element rule (inside): " + str(qq)) else: qq, k = (q1, q2, Q[k]), k + 1 if qq in _rules_ambiguous: rules.append((_rules_ambiguous[qq], edges[i])) else: raise NotImplementedError("3 element rule (edge): " + str(qq)) q1 = qq[-1] return rules def _reverse_intervals(intervals): """Reverse intervals for traversal from right to left and from top to bottom. """ return [ ((b, a), indices, f) for (a, b), indices, f in reversed(intervals) ] def _winding_number(T, field): """Compute the winding number of the input polynomial, i.e. the number of roots. """ return int(sum([ field(*_values[t][i]) for t, i in T ]) / field(2)) def dup_count_complex_roots(f, K, inf=None, sup=None, exclude=None): """Count all roots in [u + v*I, s + t*I] rectangle using Collins-Krandick algorithm. """ if not K.is_ZZ and not K.is_QQ: raise DomainError("complex root counting is not supported over %s" % K) if K.is_ZZ: R, F = K, K.get_field() else: R, F = K.get_ring(), K f = dup_convert(f, K, F) if inf is None or sup is None: _, lc = dup_degree(f), abs(dup_LC(f, F)) B = 2*max([ F.quo(abs(c), lc) for c in f ]) if inf is None: (u, v) = (-B, -B) else: (u, v) = inf if sup is None: (s, t) = (+B, +B) else: (s, t) = sup f1, f2 = dup_real_imag(f, F) f1L1F = dmp_eval_in(f1, v, 1, 1, F) f2L1F = dmp_eval_in(f2, v, 1, 1, F) _, f1L1R = dup_clear_denoms(f1L1F, F, R, convert=True) _, f2L1R = dup_clear_denoms(f2L1F, F, R, convert=True) f1L2F = dmp_eval_in(f1, s, 0, 1, F) f2L2F = dmp_eval_in(f2, s, 0, 1, F) _, f1L2R = dup_clear_denoms(f1L2F, F, R, convert=True) _, f2L2R = dup_clear_denoms(f2L2F, F, R, convert=True) f1L3F = dmp_eval_in(f1, t, 1, 1, F) f2L3F = dmp_eval_in(f2, t, 1, 1, F) _, f1L3R = dup_clear_denoms(f1L3F, F, R, convert=True) _, f2L3R = dup_clear_denoms(f2L3F, F, R, convert=True) f1L4F = dmp_eval_in(f1, u, 0, 1, F) f2L4F = dmp_eval_in(f2, u, 0, 1, F) _, f1L4R = dup_clear_denoms(f1L4F, F, R, convert=True) _, f2L4R = dup_clear_denoms(f2L4F, F, R, convert=True) S_L1 = [f1L1R, f2L1R] S_L2 = [f1L2R, f2L2R] S_L3 = [f1L3R, f2L3R] S_L4 = [f1L4R, f2L4R] I_L1 = dup_isolate_real_roots_list(S_L1, R, inf=u, sup=s, fast=True, basis=True, strict=True) I_L2 = dup_isolate_real_roots_list(S_L2, R, inf=v, sup=t, fast=True, basis=True, strict=True) I_L3 = dup_isolate_real_roots_list(S_L3, R, inf=u, sup=s, fast=True, basis=True, strict=True) I_L4 = dup_isolate_real_roots_list(S_L4, R, inf=v, sup=t, fast=True, basis=True, strict=True) I_L3 = _reverse_intervals(I_L3) I_L4 = _reverse_intervals(I_L4) Q_L1 = _intervals_to_quadrants(I_L1, f1L1F, f2L1F, u, s, F) Q_L2 = _intervals_to_quadrants(I_L2, f1L2F, f2L2F, v, t, F) Q_L3 = _intervals_to_quadrants(I_L3, f1L3F, f2L3F, s, u, F) Q_L4 = _intervals_to_quadrants(I_L4, f1L4F, f2L4F, t, v, F) T = _traverse_quadrants(Q_L1, Q_L2, Q_L3, Q_L4, exclude=exclude) return _winding_number(T, F) def _vertical_bisection(N, a, b, I, Q, F1, F2, f1, f2, F): """Vertical bisection step in Collins-Krandick root isolation algorithm. """ (u, v), (s, t) = a, b I_L1, I_L2, I_L3, I_L4 = I Q_L1, Q_L2, Q_L3, Q_L4 = Q f1L1F, f1L2F, f1L3F, f1L4F = F1 f2L1F, f2L2F, f2L3F, f2L4F = F2 x = (u + s) / 2 f1V = dmp_eval_in(f1, x, 0, 1, F) f2V = dmp_eval_in(f2, x, 0, 1, F) I_V = dup_isolate_real_roots_list([f1V, f2V], F, inf=v, sup=t, fast=True, strict=True, basis=True) I_L1_L, I_L1_R = [], [] I_L2_L, I_L2_R = I_V, I_L2 I_L3_L, I_L3_R = [], [] I_L4_L, I_L4_R = I_L4, _reverse_intervals(I_V) for I in I_L1: (a, b), indices, h = I if a == b: if a == x: I_L1_L.append(I) I_L1_R.append(I) elif a < x: I_L1_L.append(I) else: I_L1_R.append(I) else: if b <= x: I_L1_L.append(I) elif a >= x: I_L1_R.append(I) else: a, b = dup_refine_real_root(h, a, b, F.get_ring(), disjoint=x, fast=True) if b <= x: I_L1_L.append(((a, b), indices, h)) if a >= x: I_L1_R.append(((a, b), indices, h)) for I in I_L3: (b, a), indices, h = I if a == b: if a == x: I_L3_L.append(I) I_L3_R.append(I) elif a < x: I_L3_L.append(I) else: I_L3_R.append(I) else: if b <= x: I_L3_L.append(I) elif a >= x: I_L3_R.append(I) else: a, b = dup_refine_real_root(h, a, b, F.get_ring(), disjoint=x, fast=True) if b <= x: I_L3_L.append(((b, a), indices, h)) if a >= x: I_L3_R.append(((b, a), indices, h)) Q_L1_L = _intervals_to_quadrants(I_L1_L, f1L1F, f2L1F, u, x, F) Q_L2_L = _intervals_to_quadrants(I_L2_L, f1V, f2V, v, t, F) Q_L3_L = _intervals_to_quadrants(I_L3_L, f1L3F, f2L3F, x, u, F) Q_L4_L = Q_L4 Q_L1_R = _intervals_to_quadrants(I_L1_R, f1L1F, f2L1F, x, s, F) Q_L2_R = Q_L2 Q_L3_R = _intervals_to_quadrants(I_L3_R, f1L3F, f2L3F, s, x, F) Q_L4_R = _intervals_to_quadrants(I_L4_R, f1V, f2V, t, v, F) T_L = _traverse_quadrants(Q_L1_L, Q_L2_L, Q_L3_L, Q_L4_L, exclude=True) T_R = _traverse_quadrants(Q_L1_R, Q_L2_R, Q_L3_R, Q_L4_R, exclude=True) N_L = _winding_number(T_L, F) N_R = _winding_number(T_R, F) I_L = (I_L1_L, I_L2_L, I_L3_L, I_L4_L) Q_L = (Q_L1_L, Q_L2_L, Q_L3_L, Q_L4_L) I_R = (I_L1_R, I_L2_R, I_L3_R, I_L4_R) Q_R = (Q_L1_R, Q_L2_R, Q_L3_R, Q_L4_R) F1_L = (f1L1F, f1V, f1L3F, f1L4F) F2_L = (f2L1F, f2V, f2L3F, f2L4F) F1_R = (f1L1F, f1L2F, f1L3F, f1V) F2_R = (f2L1F, f2L2F, f2L3F, f2V) a, b = (u, v), (x, t) c, d = (x, v), (s, t) D_L = (N_L, a, b, I_L, Q_L, F1_L, F2_L) D_R = (N_R, c, d, I_R, Q_R, F1_R, F2_R) return D_L, D_R def _horizontal_bisection(N, a, b, I, Q, F1, F2, f1, f2, F): """Horizontal bisection step in Collins-Krandick root isolation algorithm. """ (u, v), (s, t) = a, b I_L1, I_L2, I_L3, I_L4 = I Q_L1, Q_L2, Q_L3, Q_L4 = Q f1L1F, f1L2F, f1L3F, f1L4F = F1 f2L1F, f2L2F, f2L3F, f2L4F = F2 y = (v + t) / 2 f1H = dmp_eval_in(f1, y, 1, 1, F) f2H = dmp_eval_in(f2, y, 1, 1, F) I_H = dup_isolate_real_roots_list([f1H, f2H], F, inf=u, sup=s, fast=True, strict=True, basis=True) I_L1_B, I_L1_U = I_L1, I_H I_L2_B, I_L2_U = [], [] I_L3_B, I_L3_U = _reverse_intervals(I_H), I_L3 I_L4_B, I_L4_U = [], [] for I in I_L2: (a, b), indices, h = I if a == b: if a == y: I_L2_B.append(I) I_L2_U.append(I) elif a < y: I_L2_B.append(I) else: I_L2_U.append(I) else: if b <= y: I_L2_B.append(I) elif a >= y: I_L2_U.append(I) else: a, b = dup_refine_real_root(h, a, b, F.get_ring(), disjoint=y, fast=True) if b <= y: I_L2_B.append(((a, b), indices, h)) if a >= y: I_L2_U.append(((a, b), indices, h)) for I in I_L4: (b, a), indices, h = I if a == b: if a == y: I_L4_B.append(I) I_L4_U.append(I) elif a < y: I_L4_B.append(I) else: I_L4_U.append(I) else: if b <= y: I_L4_B.append(I) elif a >= y: I_L4_U.append(I) else: a, b = dup_refine_real_root(h, a, b, F.get_ring(), disjoint=y, fast=True) if b <= y: I_L4_B.append(((b, a), indices, h)) if a >= y: I_L4_U.append(((b, a), indices, h)) Q_L1_B = Q_L1 Q_L2_B = _intervals_to_quadrants(I_L2_B, f1L2F, f2L2F, v, y, F) Q_L3_B = _intervals_to_quadrants(I_L3_B, f1H, f2H, s, u, F) Q_L4_B = _intervals_to_quadrants(I_L4_B, f1L4F, f2L4F, y, v, F) Q_L1_U = _intervals_to_quadrants(I_L1_U, f1H, f2H, u, s, F) Q_L2_U = _intervals_to_quadrants(I_L2_U, f1L2F, f2L2F, y, t, F) Q_L3_U = Q_L3 Q_L4_U = _intervals_to_quadrants(I_L4_U, f1L4F, f2L4F, t, y, F) T_B = _traverse_quadrants(Q_L1_B, Q_L2_B, Q_L3_B, Q_L4_B, exclude=True) T_U = _traverse_quadrants(Q_L1_U, Q_L2_U, Q_L3_U, Q_L4_U, exclude=True) N_B = _winding_number(T_B, F) N_U = _winding_number(T_U, F) I_B = (I_L1_B, I_L2_B, I_L3_B, I_L4_B) Q_B = (Q_L1_B, Q_L2_B, Q_L3_B, Q_L4_B) I_U = (I_L1_U, I_L2_U, I_L3_U, I_L4_U) Q_U = (Q_L1_U, Q_L2_U, Q_L3_U, Q_L4_U) F1_B = (f1L1F, f1L2F, f1H, f1L4F) F2_B = (f2L1F, f2L2F, f2H, f2L4F) F1_U = (f1H, f1L2F, f1L3F, f1L4F) F2_U = (f2H, f2L2F, f2L3F, f2L4F) a, b = (u, v), (s, y) c, d = (u, y), (s, t) D_B = (N_B, a, b, I_B, Q_B, F1_B, F2_B) D_U = (N_U, c, d, I_U, Q_U, F1_U, F2_U) return D_B, D_U def _depth_first_select(rectangles): """Find a rectangle of minimum area for bisection. """ min_area, j = None, None for i, (_, (u, v), (s, t), _, _, _, _) in enumerate(rectangles): area = (s - u)*(t - v) if min_area is None or area < min_area: min_area, j = area, i return rectangles.pop(j) def _rectangle_small_p(a, b, eps): """Return ``True`` if the given rectangle is small enough. """ (u, v), (s, t) = a, b if eps is not None: return s - u < eps and t - v < eps else: return True def dup_isolate_complex_roots_sqf(f, K, eps=None, inf=None, sup=None, blackbox=False): """Isolate complex roots of a square-free polynomial using Collins-Krandick algorithm. """ if not K.is_ZZ and not K.is_QQ: raise DomainError("isolation of complex roots is not supported over %s" % K) if dup_degree(f) <= 0: return [] if K.is_ZZ: F = K.get_field() else: F = K f = dup_convert(f, K, F) lc = abs(dup_LC(f, F)) B = 2*max([ F.quo(abs(c), lc) for c in f ]) (u, v), (s, t) = (-B, F.zero), (B, B) if inf is not None: u = inf if sup is not None: s = sup if v < 0 or t <= v or s <= u: raise ValueError("not a valid complex isolation rectangle") f1, f2 = dup_real_imag(f, F) f1L1 = dmp_eval_in(f1, v, 1, 1, F) f2L1 = dmp_eval_in(f2, v, 1, 1, F) f1L2 = dmp_eval_in(f1, s, 0, 1, F) f2L2 = dmp_eval_in(f2, s, 0, 1, F) f1L3 = dmp_eval_in(f1, t, 1, 1, F) f2L3 = dmp_eval_in(f2, t, 1, 1, F) f1L4 = dmp_eval_in(f1, u, 0, 1, F) f2L4 = dmp_eval_in(f2, u, 0, 1, F) S_L1 = [f1L1, f2L1] S_L2 = [f1L2, f2L2] S_L3 = [f1L3, f2L3] S_L4 = [f1L4, f2L4] I_L1 = dup_isolate_real_roots_list(S_L1, F, inf=u, sup=s, fast=True, strict=True, basis=True) I_L2 = dup_isolate_real_roots_list(S_L2, F, inf=v, sup=t, fast=True, strict=True, basis=True) I_L3 = dup_isolate_real_roots_list(S_L3, F, inf=u, sup=s, fast=True, strict=True, basis=True) I_L4 = dup_isolate_real_roots_list(S_L4, F, inf=v, sup=t, fast=True, strict=True, basis=True) I_L3 = _reverse_intervals(I_L3) I_L4 = _reverse_intervals(I_L4) Q_L1 = _intervals_to_quadrants(I_L1, f1L1, f2L1, u, s, F) Q_L2 = _intervals_to_quadrants(I_L2, f1L2, f2L2, v, t, F) Q_L3 = _intervals_to_quadrants(I_L3, f1L3, f2L3, s, u, F) Q_L4 = _intervals_to_quadrants(I_L4, f1L4, f2L4, t, v, F) T = _traverse_quadrants(Q_L1, Q_L2, Q_L3, Q_L4) N = _winding_number(T, F) if not N: return [] I = (I_L1, I_L2, I_L3, I_L4) Q = (Q_L1, Q_L2, Q_L3, Q_L4) F1 = (f1L1, f1L2, f1L3, f1L4) F2 = (f2L1, f2L2, f2L3, f2L4) rectangles, roots = [(N, (u, v), (s, t), I, Q, F1, F2)], [] while rectangles: N, (u, v), (s, t), I, Q, F1, F2 = _depth_first_select(rectangles) if s - u > t - v: D_L, D_R = _vertical_bisection(N, (u, v), (s, t), I, Q, F1, F2, f1, f2, F) N_L, a, b, I_L, Q_L, F1_L, F2_L = D_L N_R, c, d, I_R, Q_R, F1_R, F2_R = D_R if N_L >= 1: if N_L == 1 and _rectangle_small_p(a, b, eps): roots.append(ComplexInterval(a, b, I_L, Q_L, F1_L, F2_L, f1, f2, F)) else: rectangles.append(D_L) if N_R >= 1: if N_R == 1 and _rectangle_small_p(c, d, eps): roots.append(ComplexInterval(c, d, I_R, Q_R, F1_R, F2_R, f1, f2, F)) else: rectangles.append(D_R) else: D_B, D_U = _horizontal_bisection(N, (u, v), (s, t), I, Q, F1, F2, f1, f2, F) N_B, a, b, I_B, Q_B, F1_B, F2_B = D_B N_U, c, d, I_U, Q_U, F1_U, F2_U = D_U if N_B >= 1: if N_B == 1 and _rectangle_small_p(a, b, eps): roots.append(ComplexInterval( a, b, I_B, Q_B, F1_B, F2_B, f1, f2, F)) else: rectangles.append(D_B) if N_U >= 1: if N_U == 1 and _rectangle_small_p(c, d, eps): roots.append(ComplexInterval( c, d, I_U, Q_U, F1_U, F2_U, f1, f2, F)) else: rectangles.append(D_U) _roots, roots = sorted(roots, key=lambda r: (r.ax, r.ay)), [] for root in _roots: roots.extend([root.conjugate(), root]) if blackbox: return roots else: return [ r.as_tuple() for r in roots ] def dup_isolate_all_roots_sqf(f, K, eps=None, inf=None, sup=None, fast=False, blackbox=False): """Isolate real and complex roots of a square-free polynomial ``f``. """ return ( dup_isolate_real_roots_sqf( f, K, eps=eps, inf=inf, sup=sup, fast=fast, blackbox=blackbox), dup_isolate_complex_roots_sqf(f, K, eps=eps, inf=inf, sup=sup, blackbox=blackbox)) def dup_isolate_all_roots(f, K, eps=None, inf=None, sup=None, fast=False): """Isolate real and complex roots of a non-square-free polynomial ``f``. """ if not K.is_ZZ and not K.is_QQ: raise DomainError("isolation of real and complex roots is not supported over %s" % K) _, factors = dup_sqf_list(f, K) if len(factors) == 1: ((f, k),) = factors real_part, complex_part = dup_isolate_all_roots_sqf( f, K, eps=eps, inf=inf, sup=sup, fast=fast) real_part = [ ((a, b), k) for (a, b) in real_part ] complex_part = [ ((a, b), k) for (a, b) in complex_part ] return real_part, complex_part else: raise NotImplementedError( "only trivial square-free polynomials are supported") class RealInterval(object): """A fully qualified representation of a real isolation interval. """ def __init__(self, data, f, dom): """Initialize new real interval with complete information. """ if len(data) == 2: s, t = data self.neg = False if s < 0: if t <= 0: f, s, t, self.neg = dup_mirror(f, dom), -t, -s, True else: raise ValueError("can't refine a real root in (%s, %s)" % (s, t)) a, b, c, d = _mobius_from_interval((s, t), dom.get_field()) f = dup_transform(f, dup_strip([a, b]), dup_strip([c, d]), dom) self.mobius = a, b, c, d else: self.mobius = data[:-1] self.neg = data[-1] self.f, self.dom = f, dom @property def func(self): return RealInterval @property def args(self): i = self return (i.mobius + (i.neg,), i.f, i.dom) def __eq__(self, other): if type(other) != type(self): return False return self.args == other.args @property def a(self): """Return the position of the left end. """ field = self.dom.get_field() a, b, c, d = self.mobius if not self.neg: if a*d < b*c: return field(a, c) return field(b, d) else: if a*d > b*c: return -field(a, c) return -field(b, d) @property def b(self): """Return the position of the right end. """ was = self.neg self.neg = not was rv = -self.a self.neg = was return rv @property def dx(self): """Return width of the real isolating interval. """ return self.b - self.a @property def center(self): """Return the center of the real isolating interval. """ return (self.a + self.b)/2 def as_tuple(self): """Return tuple representation of real isolating interval. """ return (self.a, self.b) def __repr__(self): return "(%s, %s)" % (self.a, self.b) def is_disjoint(self, other): """Return ``True`` if two isolation intervals are disjoint. """ if isinstance(other, RealInterval): return (self.b <= other.a or other.b <= self.a) assert isinstance(other, ComplexInterval) return (self.b <= other.ax or other.bx <= self.a or other.ay*other.by > 0) def _inner_refine(self): """Internal one step real root refinement procedure. """ if self.mobius is None: return self f, mobius = dup_inner_refine_real_root( self.f, self.mobius, self.dom, steps=1, mobius=True) return RealInterval(mobius + (self.neg,), f, self.dom) def refine_disjoint(self, other): """Refine an isolating interval until it is disjoint with another one. """ expr = self while not expr.is_disjoint(other): expr, other = expr._inner_refine(), other._inner_refine() return expr, other def refine_size(self, dx): """Refine an isolating interval until it is of sufficiently small size. """ expr = self while not (expr.dx < dx): expr = expr._inner_refine() return expr def refine_step(self, steps=1): """Perform several steps of real root refinement algorithm. """ expr = self for _ in range(steps): expr = expr._inner_refine() return expr def refine(self): """Perform one step of real root refinement algorithm. """ return self._inner_refine() class ComplexInterval(object): """A fully qualified representation of a complex isolation interval. The printed form is shown as (ax, bx) x (ay, by) where (ax, ay) and (bx, by) are the coordinates of the southwest and northeast corners of the interval's rectangle, respectively. Examples ======== >>> from sympy import CRootOf, Rational, S >>> from sympy.abc import x >>> CRootOf.clear_cache() # for doctest reproducibility >>> root = CRootOf(x**10 - 2*x + 3, 9) >>> i = root._get_interval(); i (3/64, 3/32) x (9/8, 75/64) The real part of the root lies within the range [0, 3/4] while the imaginary part lies within the range [9/8, 3/2]: >>> root.n(3) 0.0766 + 1.14*I The width of the ranges in the x and y directions on the complex plane are: >>> i.dx, i.dy (3/64, 3/64) The center of the range is >>> i.center (9/128, 147/128) The northeast coordinate of the rectangle bounding the root in the complex plane is given by attribute b and the x and y components are accessed by bx and by: >>> i.b, i.bx, i.by ((3/32, 75/64), 3/32, 75/64) The southwest coordinate is similarly given by i.a >>> i.a, i.ax, i.ay ((3/64, 9/8), 3/64, 9/8) Although the interval prints to show only the real and imaginary range of the root, all the information of the underlying root is contained as properties of the interval. For example, an interval with a nonpositive imaginary range is considered to be the conjugate. Since the y values of y are in the range [0, 1/4] it is not the conjugate: >>> i.conj False The conjugate's interval is >>> ic = i.conjugate(); ic (3/64, 3/32) x (-75/64, -9/8) NOTE: the values printed still represent the x and y range in which the root -- conjugate, in this case -- is located, but the underlying a and b values of a root and its conjugate are the same: >>> assert i.a == ic.a and i.b == ic.b What changes are the reported coordinates of the bounding rectangle: >>> (i.ax, i.ay), (i.bx, i.by) ((3/64, 9/8), (3/32, 75/64)) >>> (ic.ax, ic.ay), (ic.bx, ic.by) ((3/64, -75/64), (3/32, -9/8)) The interval can be refined once: >>> i # for reference, this is the current interval (3/64, 3/32) x (9/8, 75/64) >>> i.refine() (3/64, 3/32) x (9/8, 147/128) Several refinement steps can be taken: >>> i.refine_step(2) # 2 steps (9/128, 3/32) x (9/8, 147/128) It is also possible to refine to a given tolerance: >>> tol = min(i.dx, i.dy)/2 >>> i.refine_size(tol) (9/128, 21/256) x (9/8, 291/256) A disjoint interval is one whose bounding rectangle does not overlap with another. An interval, necessarily, is not disjoint with itself, but any interval is disjoint with a conjugate since the conjugate rectangle will always be in the lower half of the complex plane and the non-conjugate in the upper half: >>> i.is_disjoint(i), i.is_disjoint(i.conjugate()) (False, True) The following interval j is not disjoint from i: >>> close = CRootOf(x**10 - 2*x + 300/S(101), 9) >>> j = close._get_interval(); j (75/1616, 75/808) x (225/202, 1875/1616) >>> i.is_disjoint(j) False The two can be made disjoint, however: >>> newi, newj = i.refine_disjoint(j) >>> newi (39/512, 159/2048) x (2325/2048, 4653/4096) >>> newj (3975/51712, 2025/25856) x (29325/25856, 117375/103424) Even though the real ranges overlap, the imaginary do not, so the roots have been resolved as distinct. Intervals are disjoint when either the real or imaginary component of the intervals is distinct. In the case above, the real components have not been resolved (so we don't know, yet, which root has the smaller real part) but the imaginary part of ``close`` is larger than ``root``: >>> close.n(3) 0.0771 + 1.13*I >>> root.n(3) 0.0766 + 1.14*I """ def __init__(self, a, b, I, Q, F1, F2, f1, f2, dom, conj=False): """Initialize new complex interval with complete information. """ # a and b are the SW and NE corner of the bounding interval, # (ax, ay) and (bx, by), respectively, for the NON-CONJUGATE # root (the one with the positive imaginary part); when working # with the conjugate, the a and b value are still non-negative # but the ay, by are reversed and have oppositite sign self.a, self.b = a, b self.I, self.Q = I, Q self.f1, self.F1 = f1, F1 self.f2, self.F2 = f2, F2 self.dom = dom self.conj = conj @property def func(self): return ComplexInterval @property def args(self): i = self return (i.a, i.b, i.I, i.Q, i.F1, i.F2, i.f1, i.f2, i.dom, i.conj) def __eq__(self, other): if type(other) != type(self): return False return self.args == other.args @property def ax(self): """Return ``x`` coordinate of south-western corner. """ return self.a[0] @property def ay(self): """Return ``y`` coordinate of south-western corner. """ if not self.conj: return self.a[1] else: return -self.b[1] @property def bx(self): """Return ``x`` coordinate of north-eastern corner. """ return self.b[0] @property def by(self): """Return ``y`` coordinate of north-eastern corner. """ if not self.conj: return self.b[1] else: return -self.a[1] @property def dx(self): """Return width of the complex isolating interval. """ return self.b[0] - self.a[0] @property def dy(self): """Return height of the complex isolating interval. """ return self.b[1] - self.a[1] @property def center(self): """Return the center of the complex isolating interval. """ return ((self.ax + self.bx)/2, (self.ay + self.by)/2) def as_tuple(self): """Return tuple representation of the complex isolating interval's SW and NE corners, respectively. """ return ((self.ax, self.ay), (self.bx, self.by)) def __repr__(self): return "(%s, %s) x (%s, %s)" % (self.ax, self.bx, self.ay, self.by) def conjugate(self): """This complex interval really is located in lower half-plane. """ return ComplexInterval(self.a, self.b, self.I, self.Q, self.F1, self.F2, self.f1, self.f2, self.dom, conj=True) def is_disjoint(self, other): """Return ``True`` if two isolation intervals are disjoint. """ if isinstance(other, RealInterval): return other.is_disjoint(self) if self.conj != other.conj: # above and below real axis return True re_distinct = (self.bx <= other.ax or other.bx <= self.ax) if re_distinct: return True im_distinct = (self.by <= other.ay or other.by <= self.ay) return im_distinct def _inner_refine(self): """Internal one step complex root refinement procedure. """ (u, v), (s, t) = self.a, self.b I, Q = self.I, self.Q f1, F1 = self.f1, self.F1 f2, F2 = self.f2, self.F2 dom = self.dom if s - u > t - v: D_L, D_R = _vertical_bisection(1, (u, v), (s, t), I, Q, F1, F2, f1, f2, dom) if D_L[0] == 1: _, a, b, I, Q, F1, F2 = D_L else: _, a, b, I, Q, F1, F2 = D_R else: D_B, D_U = _horizontal_bisection(1, (u, v), (s, t), I, Q, F1, F2, f1, f2, dom) if D_B[0] == 1: _, a, b, I, Q, F1, F2 = D_B else: _, a, b, I, Q, F1, F2 = D_U return ComplexInterval(a, b, I, Q, F1, F2, f1, f2, dom, self.conj) def refine_disjoint(self, other): """Refine an isolating interval until it is disjoint with another one. """ expr = self while not expr.is_disjoint(other): expr, other = expr._inner_refine(), other._inner_refine() return expr, other def refine_size(self, dx, dy=None): """Refine an isolating interval until it is of sufficiently small size. """ if dy is None: dy = dx expr = self while not (expr.dx < dx and expr.dy < dy): expr = expr._inner_refine() return expr def refine_step(self, steps=1): """Perform several steps of complex root refinement algorithm. """ expr = self for _ in range(steps): expr = expr._inner_refine() return expr def refine(self): """Perform one step of complex root refinement algorithm. """ return self._inner_refine()

4f19bf1c3bf7ff4cccbe41f25c35c811e8eaf4931a09f588d648bf65abf428df

"""Efficient functions for generating orthogonal polynomials. """ from __future__ import print_function, division from sympy import Dummy from sympy.core.compatibility import range from sympy.polys.constructor import construct_domain from sympy.polys.densearith import ( dup_mul, dup_mul_ground, dup_lshift, dup_sub, dup_add ) from sympy.polys.domains import ZZ, QQ from sympy.polys.polyclasses import DMP from sympy.polys.polytools import Poly, PurePoly from sympy.utilities import public def dup_jacobi(n, a, b, K): """Low-level implementation of Jacobi polynomials. """ seq = [[K.one], [(a + b + K(2))/K(2), (a - b)/K(2)]] for i in range(2, n + 1): den = K(i)*(a + b + i)*(a + b + K(2)*i - K(2)) f0 = (a + b + K(2)*i - K.one) * (a*a - b*b) / (K(2)*den) f1 = (a + b + K(2)*i - K.one) * (a + b + K(2)*i - K(2)) * (a + b + K(2)*i) / (K(2)*den) f2 = (a + i - K.one)*(b + i - K.one)*(a + b + K(2)*i) / den p0 = dup_mul_ground(seq[-1], f0, K) p1 = dup_mul_ground(dup_lshift(seq[-1], 1, K), f1, K) p2 = dup_mul_ground(seq[-2], f2, K) seq.append(dup_sub(dup_add(p0, p1, K), p2, K)) return seq[n] @public def jacobi_poly(n, a, b, x=None, polys=False): """Generates Jacobi polynomial of degree `n` in `x`. Parameters ========== n : int `n` decides the degree of polynomial a Lower limit of minimal domain for the list of coefficients. b Upper limit of minimal domain for the list of coefficients. x : optional polys : bool, optional ``polys=True`` returns an expression, otherwise (default) returns an expression. """ if n < 0: raise ValueError("can't generate Jacobi polynomial of degree %s" % n) K, v = construct_domain([a, b], field=True) poly = DMP(dup_jacobi(int(n), v[0], v[1], K), K) if x is not None: poly = Poly.new(poly, x) else: poly = PurePoly.new(poly, Dummy('x')) return poly if polys else poly.as_expr() def dup_gegenbauer(n, a, K): """Low-level implementation of Gegenbauer polynomials. """ seq = [[K.one], [K(2)*a, K.zero]] for i in range(2, n + 1): f1 = K(2) * (i + a - K.one) / i f2 = (i + K(2)*a - K(2)) / i p1 = dup_mul_ground(dup_lshift(seq[-1], 1, K), f1, K) p2 = dup_mul_ground(seq[-2], f2, K) seq.append(dup_sub(p1, p2, K)) return seq[n] def gegenbauer_poly(n, a, x=None, polys=False): """Generates Gegenbauer polynomial of degree `n` in `x`. Parameters ========== n : int `n` decides the degree of polynomial x : optional a Decides minimal domain for the list of coefficients. polys : bool, optional ``polys=True`` returns an expression, otherwise (default) returns an expression. """ if n < 0: raise ValueError( "can't generate Gegenbauer polynomial of degree %s" % n) K, a = construct_domain(a, field=True) poly = DMP(dup_gegenbauer(int(n), a, K), K) if x is not None: poly = Poly.new(poly, x) else: poly = PurePoly.new(poly, Dummy('x')) return poly if polys else poly.as_expr() def dup_chebyshevt(n, K): """Low-level implementation of Chebyshev polynomials of the 1st kind. """ seq = [[K.one], [K.one, K.zero]] for i in range(2, n + 1): a = dup_mul_ground(dup_lshift(seq[-1], 1, K), K(2), K) seq.append(dup_sub(a, seq[-2], K)) return seq[n] @public def chebyshevt_poly(n, x=None, polys=False): """Generates Chebyshev polynomial of the first kind of degree `n` in `x`. Parameters ========== n : int `n` decides the degree of polynomial x : optional polys : bool, optional ``polys=True`` returns an expression, otherwise (default) returns an expression. """ if n < 0: raise ValueError( "can't generate 1st kind Chebyshev polynomial of degree %s" % n) poly = DMP(dup_chebyshevt(int(n), ZZ), ZZ) if x is not None: poly = Poly.new(poly, x) else: poly = PurePoly.new(poly, Dummy('x')) return poly if polys else poly.as_expr() def dup_chebyshevu(n, K): """Low-level implementation of Chebyshev polynomials of the 2nd kind. """ seq = [[K.one], [K(2), K.zero]] for i in range(2, n + 1): a = dup_mul_ground(dup_lshift(seq[-1], 1, K), K(2), K) seq.append(dup_sub(a, seq[-2], K)) return seq[n] @public def chebyshevu_poly(n, x=None, polys=False): """Generates Chebyshev polynomial of the second kind of degree `n` in `x`. Parameters ========== n : int `n` decides the degree of polynomial x : optional polys : bool, optional ``polys=True`` returns an expression, otherwise (default) returns an expression. """ if n < 0: raise ValueError( "can't generate 2nd kind Chebyshev polynomial of degree %s" % n) poly = DMP(dup_chebyshevu(int(n), ZZ), ZZ) if x is not None: poly = Poly.new(poly, x) else: poly = PurePoly.new(poly, Dummy('x')) return poly if polys else poly.as_expr() def dup_hermite(n, K): """Low-level implementation of Hermite polynomials. """ seq = [[K.one], [K(2), K.zero]] for i in range(2, n + 1): a = dup_lshift(seq[-1], 1, K) b = dup_mul_ground(seq[-2], K(i - 1), K) c = dup_mul_ground(dup_sub(a, b, K), K(2), K) seq.append(c) return seq[n] @public def hermite_poly(n, x=None, polys=False): """Generates Hermite polynomial of degree `n` in `x`. Parameters ========== n : int `n` decides the degree of polynomial x : optional polys : bool, optional ``polys=True`` returns an expression, otherwise (default) returns an expression. """ if n < 0: raise ValueError("can't generate Hermite polynomial of degree %s" % n) poly = DMP(dup_hermite(int(n), ZZ), ZZ) if x is not None: poly = Poly.new(poly, x) else: poly = PurePoly.new(poly, Dummy('x')) return poly if polys else poly.as_expr() def dup_legendre(n, K): """Low-level implementation of Legendre polynomials. """ seq = [[K.one], [K.one, K.zero]] for i in range(2, n + 1): a = dup_mul_ground(dup_lshift(seq[-1], 1, K), K(2*i - 1, i), K) b = dup_mul_ground(seq[-2], K(i - 1, i), K) seq.append(dup_sub(a, b, K)) return seq[n] @public def legendre_poly(n, x=None, polys=False): """Generates Legendre polynomial of degree `n` in `x`. Parameters ========== n : int `n` decides the degree of polynomial x : optional polys : bool, optional ``polys=True`` returns an expression, otherwise (default) returns an expression. """ if n < 0: raise ValueError("can't generate Legendre polynomial of degree %s" % n) poly = DMP(dup_legendre(int(n), QQ), QQ) if x is not None: poly = Poly.new(poly, x) else: poly = PurePoly.new(poly, Dummy('x')) return poly if polys else poly.as_expr() def dup_laguerre(n, alpha, K): """Low-level implementation of Laguerre polynomials. """ seq = [[K.zero], [K.one]] for i in range(1, n + 1): a = dup_mul(seq[-1], [-K.one/i, alpha/i + K(2*i - 1)/i], K) b = dup_mul_ground(seq[-2], alpha/i + K(i - 1)/i, K) seq.append(dup_sub(a, b, K)) return seq[-1] @public def laguerre_poly(n, x=None, alpha=None, polys=False): """Generates Laguerre polynomial of degree `n` in `x`. Parameters ========== n : int `n` decides the degree of polynomial x : optional alpha Decides minimal domain for the list of coefficients. polys : bool, optional ``polys=True`` returns an expression, otherwise (default) returns an expression. """ if n < 0: raise ValueError("can't generate Laguerre polynomial of degree %s" % n) if alpha is not None: K, alpha = construct_domain( alpha, field=True) # XXX: ground_field=True else: K, alpha = QQ, QQ(0) poly = DMP(dup_laguerre(int(n), alpha, K), K) if x is not None: poly = Poly.new(poly, x) else: poly = PurePoly.new(poly, Dummy('x')) return poly if polys else poly.as_expr() def dup_spherical_bessel_fn(n, K): """ Low-level implementation of fn(n, x) """ seq = [[K.one], [K.one, K.zero]] for i in range(2, n + 1): a = dup_mul_ground(dup_lshift(seq[-1], 1, K), K(2*i - 1), K) seq.append(dup_sub(a, seq[-2], K)) return dup_lshift(seq[n], 1, K) def dup_spherical_bessel_fn_minus(n, K): """ Low-level implementation of fn(-n, x) """ seq = [[K.one, K.zero], [K.zero]] for i in range(2, n + 1): a = dup_mul_ground(dup_lshift(seq[-1], 1, K), K(3 - 2*i), K) seq.append(dup_sub(a, seq[-2], K)) return seq[n] def spherical_bessel_fn(n, x=None, polys=False): """ Coefficients for the spherical Bessel functions. Those are only needed in the jn() function. The coefficients are calculated from: fn(0, z) = 1/z fn(1, z) = 1/z**2 fn(n-1, z) + fn(n+1, z) == (2*n+1)/z * fn(n, z) Parameters ========== n : int `n` decides the degree of polynomial x : optional polys : bool, optional ``polys=True`` returns an expression, otherwise (default) returns an expression. Examples ======== >>> from sympy.polys.orthopolys import spherical_bessel_fn as fn >>> from sympy import Symbol >>> z = Symbol("z") >>> fn(1, z) z**(-2) >>> fn(2, z) -1/z + 3/z**3 >>> fn(3, z) -6/z**2 + 15/z**4 >>> fn(4, z) 1/z - 45/z**3 + 105/z**5 """ if n < 0: dup = dup_spherical_bessel_fn_minus(-int(n), ZZ) else: dup = dup_spherical_bessel_fn(int(n), ZZ) poly = DMP(dup, ZZ) if x is not None: poly = Poly.new(poly, 1/x) else: poly = PurePoly.new(poly, 1/Dummy('x')) return poly if polys else poly.as_expr()

21c45aeb6339a7e50862531c8ec3a51c306cd66f441f224ceaf7f664f763b731

""" This module contains functions for two multivariate resultants. These are: - Dixon's resultant. - Macaulay's resultant. Multivariate resultants are used to identify whether a multivariate system has common roots. That is when the resultant is equal to zero. """ from sympy import IndexedBase, Matrix, Mul, Poly from sympy import rem, prod, total_degree from sympy.core.compatibility import range from sympy.polys.monomials import monomial_deg, itermonomials from sympy.polys.orderings import monomial_key from sympy.polys.polytools import poly_from_expr from sympy.functions.combinatorial.factorials import binomial from itertools import combinations_with_replacement class DixonResultant(): """ A class for retrieving the Dixon's resultant of a multivariate system. Examples ======== >>> from sympy.core import symbols >>> from sympy.polys.multivariate_resultants import DixonResultant >>> x, y = symbols('x, y') >>> p = x + y >>> q = x ** 2 + y ** 3 >>> h = x ** 2 + y >>> dixon = DixonResultant(variables=[x, y], polynomials=[p, q, h]) >>> poly = dixon.get_dixon_polynomial() >>> matrix = dixon.get_dixon_matrix(polynomial=poly) >>> matrix Matrix([ [ 0, 0, -1, 0, -1], [ 0, -1, 0, -1, 0], [-1, 0, 1, 0, 0], [ 0, -1, 0, 0, 1], [-1, 0, 0, 1, 0]]) >>> matrix.det() 0 See Also ======== Notebook in examples: sympy/example/notebooks. References ========== .. [1] [Kapur1994]_ .. [2] [Palancz08]_ """ def __init__(self, polynomials, variables): """ A class that takes two lists, a list of polynomials and list of variables. Returns the Dixon matrix of the multivariate system. Parameters ---------- polynomials : list of polynomials A list of m n-degree polynomials variables: list A list of all n variables """ self.polynomials = polynomials self.variables = variables self.n = len(self.variables) self.m = len(self.polynomials) a = IndexedBase("alpha") # A list of n alpha variables (the replacing variables) self.dummy_variables = [a[i] for i in range(self.n)] # A list of the d_max of each variable. self.max_degrees = [total_degree(poly, *self.variables) for poly in self.polynomials] def get_dixon_polynomial(self): r""" Returns ======= dixon_polynomial: polynomial Dixon's polynomial is calculated as: delta = Delta(A) / ((x_1 - a_1) ... (x_n - a_n)) where, A = |p_1(x_1,... x_n), ..., p_n(x_1,... x_n)| |p_1(a_1,... x_n), ..., p_n(a_1,... x_n)| |... , ..., ...| |p_1(a_1,... a_n), ..., p_n(a_1,... a_n)| """ if self.m != (self.n + 1): raise ValueError('Method invalid for given combination.') # First row rows = [self.polynomials] temp = list(self.variables) for idx in range(self.n): temp[idx] = self.dummy_variables[idx] substitution = {var: t for var, t in zip(self.variables, temp)} rows.append([f.subs(substitution) for f in self.polynomials]) A = Matrix(rows) terms = zip(self.variables, self.dummy_variables) product_of_differences = Mul(*[a - b for a, b in terms]) dixon_polynomial = (A.det() / product_of_differences).factor() return poly_from_expr(dixon_polynomial, self.dummy_variables)[0] def get_upper_degree(self): list_of_products = [self.variables[i] ** ((i + 1) * self.max_degrees[i] - 1) for i in range(self.n)] product = prod(list_of_products) product = Poly(product).monoms() return monomial_deg(*product) def get_dixon_matrix(self, polynomial): r""" Construct the Dixon matrix from the coefficients of polynomial \alpha. Each coefficient is viewed as a polynomial of x_1, ..., x_n. """ # A list of coefficients (in x_i, ..., x_n terms) of the power # products a_1, ..., a_n in Dixon's polynomial. coefficients = polynomial.coeffs() monomials = list(itermonomials(self.variables, self.get_upper_degree())) monomials = sorted(monomials, reverse=True, key=monomial_key('lex', self.variables)) dixon_matrix = Matrix([[Poly(c, *self.variables).coeff_monomial(m) for m in monomials] for c in coefficients]) keep = [column for column in range(dixon_matrix.shape[-1]) if any([element != 0 for element in dixon_matrix[:, column]])] return dixon_matrix[:, keep] class MacaulayResultant(): """ A class for calculating the Macaulay resultant. Note that the coefficients of the polynomials must be given as symbols. Examples ======== >>> from sympy.core import symbols >>> from sympy.polys.multivariate_resultants import MacaulayResultant >>> x, y, z = symbols('x, y, z') >>> a_0, a_1, a_2 = symbols('a_0, a_1, a_2') >>> b_0, b_1, b_2 = symbols('b_0, b_1, b_2') >>> c_0, c_1, c_2,c_3, c_4 = symbols('c_0, c_1, c_2, c_3, c_4') >>> f = a_0 * y - a_1 * x + a_2 * z >>> g = b_1 * x ** 2 + b_0 * y ** 2 - b_2 * z ** 2 >>> h = c_0 * y - c_1 * x ** 3 + c_2 * x ** 2 * z - c_3 * x * z ** 2 + c_4 * z ** 3 >>> mac = MacaulayResultant(polynomials=[f, g, h], variables=[x, y, z]) >>> mac.get_monomials_set() >>> matrix = mac.get_matrix() >>> submatrix = mac.get_submatrix(matrix) >>> submatrix Matrix([ [-a_1, a_0, a_2, 0], [ 0, -a_1, 0, 0], [ 0, 0, -a_1, 0], [ 0, 0, 0, -a_1]]) See Also ======== Notebook in examples: sympy/example/notebooks. References ========== .. [1] [Bruce97]_ .. [2] [Stiller96]_ """ def __init__(self, polynomials, variables): """ Parameters ========== variables: list A list of all n variables polynomials : list of sympy polynomials A list of m n-degree polynomials """ self.polynomials = polynomials self.variables = variables self.n = len(variables) # A list of the d_max of each variable. self.degrees = [total_degree(poly, *self.variables) for poly in self.polynomials] self.degree_m = self._get_degree_m() self.monomials_size = self.get_size() def _get_degree_m(self): r""" Returns ======= degree_m: int The degree_m is calculated as 1 + \sum_1 ^ n (d_i - 1), where d_i is the degree of the i polynomial """ return 1 + sum(d - 1 for d in self.degrees) def get_size(self): r""" Returns ======= size: int The size of set T. Set T is the set of all possible monomials of the n variables for degree equal to the degree_m """ return binomial(self.degree_m + self.n - 1, self.n - 1) def get_monomials_of_certain_degree(self, degree): """ Returns ======= monomials: list A list of monomials of a certain degree. """ monomials = [Mul(*monomial) for monomial in combinations_with_replacement(self.variables, degree)] return sorted(monomials, reverse=True, key=monomial_key('lex', self.variables)) def get_monomials_set(self): r""" Returns ======= self.monomial_set: set The set T. Set of all possible monomials of degree degree_m """ monomial_set = self.get_monomials_of_certain_degree(self.degree_m) self.monomial_set = monomial_set def get_row_coefficients(self): """ Returns ======= row_coefficients: list The row coefficients of Macaulay's matrix """ row_coefficients = [] divisible = [] for i in range(self.n): if i == 0: degree = self.degree_m - self.degrees[i] monomial = self.get_monomials_of_certain_degree(degree) row_coefficients.append(monomial) else: divisible.append(self.variables[i - 1] ** self.degrees[i - 1]) degree = self.degree_m - self.degrees[i] poss_rows = self.get_monomials_of_certain_degree(degree) for div in divisible: for p in poss_rows: if rem(p, div) == 0: poss_rows = [item for item in poss_rows if item != p] row_coefficients.append(poss_rows) return row_coefficients def get_matrix(self): """ Returns ======= macaulay_matrix: Matrix The Macaulay's matrix """ rows = [] row_coefficients = self.get_row_coefficients() for i in range(self.n): for multiplier in row_coefficients[i]: coefficients = [] poly = Poly(self.polynomials[i] * multiplier, *self.variables) for mono in self.monomial_set: coefficients.append(poly.coeff_monomial(mono)) rows.append(coefficients) macaulay_matrix = Matrix(rows) return macaulay_matrix def get_reduced_nonreduced(self): r""" Returns ======= reduced: list A list of the reduced monomials non_reduced: list A list of the monomials that are not reduced Definition ========== A polynomial is said to be reduced in x_i, if its degree (the maximum degree of its monomials) in x_i is less than d_i. A polynomial that is reduced in all variables but one is said simply to be reduced. """ divisible = [] for m in self.monomial_set: temp = [] for i, v in enumerate(self.variables): temp.append(bool(total_degree(m, v) >= self.degrees[i])) divisible.append(temp) reduced = [i for i, r in enumerate(divisible) if sum(r) < self.n - 1] non_reduced = [i for i, r in enumerate(divisible) if sum(r) >= self.n -1] return reduced, non_reduced def get_submatrix(self, matrix): r""" Returns ======= macaulay_submatrix: Matrix The Macaulay's matrix. Columns that are non reduced are kept. The row which contain one if the a_{i}s is dropped. a_{i}s are the coefficients of x_i ^ {d_i}. """ reduced, non_reduced = self.get_reduced_nonreduced() reduction_set = [v ** self.degrees[i] for i, v in enumerate(self.variables)] ais = list([self.polynomials[i].coeff(reduction_set[i]) for i in range(self.n)]) reduced_matrix = matrix[:, reduced] keep = [] for row in range(reduced_matrix.rows): check = [ai in reduced_matrix[row, :] for ai in ais] if True not in check: keep.append(row) return matrix[keep, non_reduced]

5f2679b7bcb3e68a6b5866ae0b64d7d1e9dfef5b39c556cca9dd7fcaeddeea5a

"""Useful utilities for higher level polynomial classes. """ from __future__ import print_function, division from sympy.core import (S, Add, Mul, Pow, Expr, expand_mul, expand_multinomial) from sympy.core.compatibility import range from sympy.core.exprtools import decompose_power, decompose_power_rat from sympy.polys.polyerrors import PolynomialError, GeneratorsError from sympy.polys.polyoptions import build_options import re _gens_order = { 'a': 301, 'b': 302, 'c': 303, 'd': 304, 'e': 305, 'f': 306, 'g': 307, 'h': 308, 'i': 309, 'j': 310, 'k': 311, 'l': 312, 'm': 313, 'n': 314, 'o': 315, 'p': 216, 'q': 217, 'r': 218, 's': 219, 't': 220, 'u': 221, 'v': 222, 'w': 223, 'x': 124, 'y': 125, 'z': 126, } _max_order = 1000 _re_gen = re.compile(r"^(.+?)(\d*)$") def _nsort(roots, separated=False): """Sort the numerical roots putting the real roots first, then sorting according to real and imaginary parts. If ``separated`` is True, then the real and imaginary roots will be returned in two lists, respectively. This routine tries to avoid issue 6137 by separating the roots into real and imaginary parts before evaluation. In addition, the sorting will raise an error if any computation cannot be done with precision. """ if not all(r.is_number for r in roots): raise NotImplementedError # see issue 6137: # get the real part of the evaluated real and imaginary parts of each root key = [[i.n(2).as_real_imag()[0] for i in r.as_real_imag()] for r in roots] # make sure the parts were computed with precision if any(i._prec == 1 for k in key for i in k): raise NotImplementedError("could not compute root with precision") # insert a key to indicate if the root has an imaginary part key = [(1 if i else 0, r, i) for r, i in key] key = sorted(zip(key, roots)) # return the real and imaginary roots separately if desired if separated: r = [] i = [] for (im, _, _), v in key: if im: i.append(v) else: r.append(v) return r, i _, roots = zip(*key) return list(roots) def _sort_gens(gens, **args): """Sort generators in a reasonably intelligent way. """ opt = build_options(args) gens_order, wrt = {}, None if opt is not None: gens_order, wrt = {}, opt.wrt for i, gen in enumerate(opt.sort): gens_order[gen] = i + 1 def order_key(gen): gen = str(gen) if wrt is not None: try: return (-len(wrt) + wrt.index(gen), gen, 0) except ValueError: pass name, index = _re_gen.match(gen).groups() if index: index = int(index) else: index = 0 try: return ( gens_order[name], name, index) except KeyError: pass try: return (_gens_order[name], name, index) except KeyError: pass return (_max_order, name, index) try: gens = sorted(gens, key=order_key) except TypeError: # pragma: no cover pass return tuple(gens) def _unify_gens(f_gens, g_gens): """Unify generators in a reasonably intelligent way. """ f_gens = list(f_gens) g_gens = list(g_gens) if f_gens == g_gens: return tuple(f_gens) gens, common, k = [], [], 0 for gen in f_gens: if gen in g_gens: common.append(gen) for i, gen in enumerate(g_gens): if gen in common: g_gens[i], k = common[k], k + 1 for gen in common: i = f_gens.index(gen) gens.extend(f_gens[:i]) f_gens = f_gens[i + 1:] i = g_gens.index(gen) gens.extend(g_gens[:i]) g_gens = g_gens[i + 1:] gens.append(gen) gens.extend(f_gens) gens.extend(g_gens) return tuple(gens) def _analyze_gens(gens): """Support for passing generators as `*gens` and `[gens]`. """ if len(gens) == 1 and hasattr(gens[0], '__iter__'): return tuple(gens[0]) else: return tuple(gens) def _sort_factors(factors, **args): """Sort low-level factors in increasing 'complexity' order. """ def order_if_multiple_key(factor): (f, n) = factor return (len(f), n, f) def order_no_multiple_key(f): return (len(f), f) if args.get('multiple', True): return sorted(factors, key=order_if_multiple_key) else: return sorted(factors, key=order_no_multiple_key) def _not_a_coeff(expr): """Do not treat NaN and infinities as valid polynomial coefficients. """ return expr in [S.NaN, S.Infinity, S.NegativeInfinity, S.ComplexInfinity] def _parallel_dict_from_expr_if_gens(exprs, opt): """Transform expressions into a multinomial form given generators. """ k, indices = len(opt.gens), {} for i, g in enumerate(opt.gens): indices[g] = i polys = [] for expr in exprs: poly = {} if expr.is_Equality: expr = expr.lhs - expr.rhs for term in Add.make_args(expr): coeff, monom = [], [0]*k for factor in Mul.make_args(term): if not _not_a_coeff(factor) and factor.is_Number: coeff.append(factor) else: try: if opt.series is False: base, exp = decompose_power(factor) if exp < 0: exp, base = -exp, Pow(base, -S.One) else: base, exp = decompose_power_rat(factor) monom[indices[base]] = exp except KeyError: if not factor.free_symbols.intersection(opt.gens): coeff.append(factor) else: raise PolynomialError("%s contains an element of " "the set of generators." % factor) monom = tuple(monom) if monom in poly: poly[monom] += Mul(*coeff) else: poly[monom] = Mul(*coeff) polys.append(poly) return polys, opt.gens def _parallel_dict_from_expr_no_gens(exprs, opt): """Transform expressions into a multinomial form and figure out generators. """ if opt.domain is not None: def _is_coeff(factor): return factor in opt.domain elif opt.extension is True: def _is_coeff(factor): return factor.is_algebraic elif opt.greedy is not False: def _is_coeff(factor): return False else: def _is_coeff(factor): return factor.is_number gens, reprs = set([]), [] for expr in exprs: terms = [] if expr.is_Equality: expr = expr.lhs - expr.rhs for term in Add.make_args(expr): coeff, elements = [], {} for factor in Mul.make_args(term): if not _not_a_coeff(factor) and (factor.is_Number or _is_coeff(factor)): coeff.append(factor) else: if opt.series is False: base, exp = decompose_power(factor) if exp < 0: exp, base = -exp, Pow(base, -S.One) else: base, exp = decompose_power_rat(factor) elements[base] = elements.setdefault(base, 0) + exp gens.add(base) terms.append((coeff, elements)) reprs.append(terms) gens = _sort_gens(gens, opt=opt) k, indices = len(gens), {} for i, g in enumerate(gens): indices[g] = i polys = [] for terms in reprs: poly = {} for coeff, term in terms: monom = [0]*k for base, exp in term.items(): monom[indices[base]] = exp monom = tuple(monom) if monom in poly: poly[monom] += Mul(*coeff) else: poly[monom] = Mul(*coeff) polys.append(poly) return polys, tuple(gens) def _dict_from_expr_if_gens(expr, opt): """Transform an expression into a multinomial form given generators. """ (poly,), gens = _parallel_dict_from_expr_if_gens((expr,), opt) return poly, gens def _dict_from_expr_no_gens(expr, opt): """Transform an expression into a multinomial form and figure out generators. """ (poly,), gens = _parallel_dict_from_expr_no_gens((expr,), opt) return poly, gens def parallel_dict_from_expr(exprs, **args): """Transform expressions into a multinomial form. """ reps, opt = _parallel_dict_from_expr(exprs, build_options(args)) return reps, opt.gens def _parallel_dict_from_expr(exprs, opt): """Transform expressions into a multinomial form. """ if opt.expand is not False: exprs = [ expr.expand() for expr in exprs ] if any(expr.is_commutative is False for expr in exprs): raise PolynomialError('non-commutative expressions are not supported') if opt.gens: reps, gens = _parallel_dict_from_expr_if_gens(exprs, opt) else: reps, gens = _parallel_dict_from_expr_no_gens(exprs, opt) return reps, opt.clone({'gens': gens}) def dict_from_expr(expr, **args): """Transform an expression into a multinomial form. """ rep, opt = _dict_from_expr(expr, build_options(args)) return rep, opt.gens def _dict_from_expr(expr, opt): """Transform an expression into a multinomial form. """ if expr.is_commutative is False: raise PolynomialError('non-commutative expressions are not supported') def _is_expandable_pow(expr): return (expr.is_Pow and expr.exp.is_positive and expr.exp.is_Integer and expr.base.is_Add) if opt.expand is not False: if not isinstance(expr, Expr): raise PolynomialError('expression must be of type Expr') expr = expr.expand() # TODO: Integrate this into expand() itself while any(_is_expandable_pow(i) or i.is_Mul and any(_is_expandable_pow(j) for j in i.args) for i in Add.make_args(expr)): expr = expand_multinomial(expr) while any(i.is_Mul and any(j.is_Add for j in i.args) for i in Add.make_args(expr)): expr = expand_mul(expr) if opt.gens: rep, gens = _dict_from_expr_if_gens(expr, opt) else: rep, gens = _dict_from_expr_no_gens(expr, opt) return rep, opt.clone({'gens': gens}) def expr_from_dict(rep, *gens): """Convert a multinomial form into an expression. """ result = [] for monom, coeff in rep.items(): term = [coeff] for g, m in zip(gens, monom): if m: term.append(Pow(g, m)) result.append(Mul(*term)) return Add(*result) parallel_dict_from_basic = parallel_dict_from_expr dict_from_basic = dict_from_expr basic_from_dict = expr_from_dict def _dict_reorder(rep, gens, new_gens): """Reorder levels using dict representation. """ gens = list(gens) monoms = rep.keys() coeffs = rep.values() new_monoms = [ [] for _ in range(len(rep)) ] used_indices = set() for gen in new_gens: try: j = gens.index(gen) used_indices.add(j) for M, new_M in zip(monoms, new_monoms): new_M.append(M[j]) except ValueError: for new_M in new_monoms: new_M.append(0) for i, _ in enumerate(gens): if i not in used_indices: for monom in monoms: if monom[i]: raise GeneratorsError("unable to drop generators") return map(tuple, new_monoms), coeffs class PicklableWithSlots(object): """ Mixin class that allows to pickle objects with ``__slots__``. Examples ======== First define a class that mixes :class:`PicklableWithSlots` in:: >>> from sympy.polys.polyutils import PicklableWithSlots >>> class Some(PicklableWithSlots): ... __slots__ = ['foo', 'bar'] ... ... def __init__(self, foo, bar): ... self.foo = foo ... self.bar = bar To make :mod:`pickle` happy in doctest we have to use these hacks:: >>> from sympy.core.compatibility import builtins >>> builtins.Some = Some >>> from sympy.polys import polyutils >>> polyutils.Some = Some Next lets see if we can create an instance, pickle it and unpickle:: >>> some = Some('abc', 10) >>> some.foo, some.bar ('abc', 10) >>> from pickle import dumps, loads >>> some2 = loads(dumps(some)) >>> some2.foo, some2.bar ('abc', 10) """ __slots__ = [] def __getstate__(self, cls=None): if cls is None: # This is the case for the instance that gets pickled cls = self.__class__ d = {} # Get all data that should be stored from super classes for c in cls.__bases__: if hasattr(c, "__getstate__"): d.update(c.__getstate__(self, c)) # Get all information that should be stored from cls and return the dict for name in cls.__slots__: if hasattr(self, name): d[name] = getattr(self, name) return d def __setstate__(self, d): # All values that were pickled are now assigned to a fresh instance for name, value in d.items(): try: setattr(self, name, value) except AttributeError: # This is needed in cases like Rational :> Half pass

104c89f3399e9289a4c10d28b80c9e9674938cd18663b027f1bf93110aa9b7dd

"""Computational algebraic field theory. """ from __future__ import print_function, division from sympy import ( S, Rational, AlgebraicNumber, Add, Mul, sympify, Dummy, expand_mul, I, pi ) from sympy.core.compatibility import reduce, range from sympy.core.exprtools import Factors from sympy.core.function import _mexpand from sympy.functions.elementary.exponential import exp from sympy.functions.elementary.trigonometric import cos, sin from sympy.ntheory import sieve from sympy.ntheory.factor_ import divisors from sympy.polys.domains import ZZ, QQ from sympy.polys.orthopolys import dup_chebyshevt from sympy.polys.polyerrors import ( IsomorphismFailed, CoercionFailed, NotAlgebraic, GeneratorsError, ) from sympy.polys.polytools import ( Poly, PurePoly, invert, factor_list, groebner, resultant, degree, poly_from_expr, parallel_poly_from_expr, lcm ) from sympy.polys.polyutils import dict_from_expr, expr_from_dict from sympy.polys.ring_series import rs_compose_add from sympy.polys.rings import ring from sympy.polys.rootoftools import CRootOf from sympy.polys.specialpolys import cyclotomic_poly from sympy.printing.lambdarepr import LambdaPrinter from sympy.simplify.radsimp import _split_gcd from sympy.simplify.simplify import _is_sum_surds from sympy.utilities import ( numbered_symbols, variations, lambdify, public, sift ) from mpmath import pslq, mp def _choose_factor(factors, x, v, dom=QQ, prec=200, bound=5): """ Return a factor having root ``v`` It is assumed that one of the factors has root ``v``. """ if isinstance(factors[0], tuple): factors = [f[0] for f in factors] if len(factors) == 1: return factors[0] points = {x:v} symbols = dom.symbols if hasattr(dom, 'symbols') else [] t = QQ(1, 10) for n in range(bound**len(symbols)): prec1 = 10 n_temp = n for s in symbols: points[s] = n_temp % bound n_temp = n_temp // bound while True: candidates = [] eps = t**(prec1 // 2) for f in factors: if abs(f.as_expr().evalf(prec1, points)) < eps: candidates.append(f) if candidates: factors = candidates if len(factors) == 1: return factors[0] if prec1 > prec: break prec1 *= 2 raise NotImplementedError("multiple candidates for the minimal polynomial of %s" % v) def _separate_sq(p): """ helper function for ``_minimal_polynomial_sq`` It selects a rational ``g`` such that the polynomial ``p`` consists of a sum of terms whose surds squared have gcd equal to ``g`` and a sum of terms with surds squared prime with ``g``; then it takes the field norm to eliminate ``sqrt(g)`` See simplify.simplify.split_surds and polytools.sqf_norm. Examples ======== >>> from sympy import sqrt >>> from sympy.abc import x >>> from sympy.polys.numberfields import _separate_sq >>> p= -x + sqrt(2) + sqrt(3) + sqrt(7) >>> p = _separate_sq(p); p -x**2 + 2*sqrt(3)*x + 2*sqrt(7)*x - 2*sqrt(21) - 8 >>> p = _separate_sq(p); p -x**4 + 4*sqrt(7)*x**3 - 32*x**2 + 8*sqrt(7)*x + 20 >>> p = _separate_sq(p); p -x**8 + 48*x**6 - 536*x**4 + 1728*x**2 - 400 """ from sympy.utilities.iterables import sift def is_sqrt(expr): return expr.is_Pow and expr.exp is S.Half # p = c1*sqrt(q1) + ... + cn*sqrt(qn) -> a = [(c1, q1), .., (cn, qn)] a = [] for y in p.args: if not y.is_Mul: if is_sqrt(y): a.append((S.One, y**2)) elif y.is_Atom: a.append((y, S.One)) elif y.is_Pow and y.exp.is_integer: a.append((y, S.One)) else: raise NotImplementedError continue T, F = sift(y.args, is_sqrt, binary=True) a.append((Mul(*F), Mul(*T)**2)) a.sort(key=lambda z: z[1]) if a[-1][1] is S.One: # there are no surds return p surds = [z for y, z in a] for i in range(len(surds)): if surds[i] != 1: break g, b1, b2 = _split_gcd(*surds[i:]) a1 = [] a2 = [] for y, z in a: if z in b1: a1.append(y*z**S.Half) else: a2.append(y*z**S.Half) p1 = Add(*a1) p2 = Add(*a2) p = _mexpand(p1**2) - _mexpand(p2**2) return p def _minimal_polynomial_sq(p, n, x): """ Returns the minimal polynomial for the ``nth-root`` of a sum of surds or ``None`` if it fails. Parameters ========== p : sum of surds n : positive integer x : variable of the returned polynomial Examples ======== >>> from sympy.polys.numberfields import _minimal_polynomial_sq >>> from sympy import sqrt >>> from sympy.abc import x >>> q = 1 + sqrt(2) + sqrt(3) >>> _minimal_polynomial_sq(q, 3, x) x**12 - 4*x**9 - 4*x**6 + 16*x**3 - 8 """ from sympy.simplify.simplify import _is_sum_surds p = sympify(p) n = sympify(n) if not n.is_Integer or not n > 0 or not _is_sum_surds(p): return None pn = p**Rational(1, n) # eliminate the square roots p -= x while 1: p1 = _separate_sq(p) if p1 is p: p = p1.subs({x:x**n}) break else: p = p1 # _separate_sq eliminates field extensions in a minimal way, so that # if n = 1 then `p = constant*(minimal_polynomial(p))` # if n > 1 it contains the minimal polynomial as a factor. if n == 1: p1 = Poly(p) if p.coeff(x**p1.degree(x)) < 0: p = -p p = p.primitive()[1] return p # by construction `p` has root `pn` # the minimal polynomial is the factor vanishing in x = pn factors = factor_list(p)[1] result = _choose_factor(factors, x, pn) return result def _minpoly_op_algebraic_element(op, ex1, ex2, x, dom, mp1=None, mp2=None): """ return the minimal polynomial for ``op(ex1, ex2)`` Parameters ========== op : operation ``Add`` or ``Mul`` ex1, ex2 : expressions for the algebraic elements x : indeterminate of the polynomials dom: ground domain mp1, mp2 : minimal polynomials for ``ex1`` and ``ex2`` or None Examples ======== >>> from sympy import sqrt, Add, Mul, QQ >>> from sympy.polys.numberfields import _minpoly_op_algebraic_element >>> from sympy.abc import x, y >>> p1 = sqrt(sqrt(2) + 1) >>> p2 = sqrt(sqrt(2) - 1) >>> _minpoly_op_algebraic_element(Mul, p1, p2, x, QQ) x - 1 >>> q1 = sqrt(y) >>> q2 = 1 / y >>> _minpoly_op_algebraic_element(Add, q1, q2, x, QQ.frac_field(y)) x**2*y**2 - 2*x*y - y**3 + 1 References ========== .. [1] https://en.wikipedia.org/wiki/Resultant .. [2] I.M. Isaacs, Proc. Amer. Math. Soc. 25 (1970), 638 "Degrees of sums in a separable field extension". """ y = Dummy(str(x)) if mp1 is None: mp1 = _minpoly_compose(ex1, x, dom) if mp2 is None: mp2 = _minpoly_compose(ex2, y, dom) else: mp2 = mp2.subs({x: y}) if op is Add: # mp1a = mp1.subs({x: x - y}) if dom == QQ: R, X = ring('X', QQ) p1 = R(dict_from_expr(mp1)[0]) p2 = R(dict_from_expr(mp2)[0]) else: (p1, p2), _ = parallel_poly_from_expr((mp1, x - y), x, y) r = p1.compose(p2) mp1a = r.as_expr() elif op is Mul: mp1a = _muly(mp1, x, y) else: raise NotImplementedError('option not available') if op is Mul or dom != QQ: r = resultant(mp1a, mp2, gens=[y, x]) else: r = rs_compose_add(p1, p2) r = expr_from_dict(r.as_expr_dict(), x) deg1 = degree(mp1, x) deg2 = degree(mp2, y) if op is Mul and deg1 == 1 or deg2 == 1: # if deg1 = 1, then mp1 = x - a; mp1a = x - y - a; # r = mp2(x - a), so that `r` is irreducible return r r = Poly(r, x, domain=dom) _, factors = r.factor_list() res = _choose_factor(factors, x, op(ex1, ex2), dom) return res.as_expr() def _invertx(p, x): """ Returns ``expand_mul(x**degree(p, x)*p.subs(x, 1/x))`` """ p1 = poly_from_expr(p, x)[0] n = degree(p1) a = [c * x**(n - i) for (i,), c in p1.terms()] return Add(*a) def _muly(p, x, y): """ Returns ``_mexpand(y**deg*p.subs({x:x / y}))`` """ p1 = poly_from_expr(p, x)[0] n = degree(p1) a = [c * x**i * y**(n - i) for (i,), c in p1.terms()] return Add(*a) def _minpoly_pow(ex, pw, x, dom, mp=None): """ Returns ``minpoly(ex**pw, x)`` Parameters ========== ex : algebraic element pw : rational number x : indeterminate of the polynomial dom: ground domain mp : minimal polynomial of ``p`` Examples ======== >>> from sympy import sqrt, QQ, Rational >>> from sympy.polys.numberfields import _minpoly_pow, minpoly >>> from sympy.abc import x, y >>> p = sqrt(1 + sqrt(2)) >>> _minpoly_pow(p, 2, x, QQ) x**2 - 2*x - 1 >>> minpoly(p**2, x) x**2 - 2*x - 1 >>> _minpoly_pow(y, Rational(1, 3), x, QQ.frac_field(y)) x**3 - y >>> minpoly(y**Rational(1, 3), x) x**3 - y """ pw = sympify(pw) if not mp: mp = _minpoly_compose(ex, x, dom) if not pw.is_rational: raise NotAlgebraic("%s doesn't seem to be an algebraic element" % ex) if pw < 0: if mp == x: raise ZeroDivisionError('%s is zero' % ex) mp = _invertx(mp, x) if pw == -1: return mp pw = -pw ex = 1/ex y = Dummy(str(x)) mp = mp.subs({x: y}) n, d = pw.as_numer_denom() res = Poly(resultant(mp, x**d - y**n, gens=[y]), x, domain=dom) _, factors = res.factor_list() res = _choose_factor(factors, x, ex**pw, dom) return res.as_expr() def _minpoly_add(x, dom, *a): """ returns ``minpoly(Add(*a), dom, x)`` """ mp = _minpoly_op_algebraic_element(Add, a[0], a[1], x, dom) p = a[0] + a[1] for px in a[2:]: mp = _minpoly_op_algebraic_element(Add, p, px, x, dom, mp1=mp) p = p + px return mp def _minpoly_mul(x, dom, *a): """ returns ``minpoly(Mul(*a), dom, x)`` """ mp = _minpoly_op_algebraic_element(Mul, a[0], a[1], x, dom) p = a[0] * a[1] for px in a[2:]: mp = _minpoly_op_algebraic_element(Mul, p, px, x, dom, mp1=mp) p = p * px return mp def _minpoly_sin(ex, x): """ Returns the minimal polynomial of ``sin(ex)`` see http://mathworld.wolfram.com/TrigonometryAngles.html """ c, a = ex.args[0].as_coeff_Mul() if a is pi: if c.is_rational: n = c.q q = sympify(n) if q.is_prime: # for a = pi*p/q with q odd prime, using chebyshevt # write sin(q*a) = mp(sin(a))*sin(a); # the roots of mp(x) are sin(pi*p/q) for p = 1,..., q - 1 a = dup_chebyshevt(n, ZZ) return Add(*[x**(n - i - 1)*a[i] for i in range(n)]) if c.p == 1: if q == 9: return 64*x**6 - 96*x**4 + 36*x**2 - 3 if n % 2 == 1: # for a = pi*p/q with q odd, use # sin(q*a) = 0 to see that the minimal polynomial must be # a factor of dup_chebyshevt(n, ZZ) a = dup_chebyshevt(n, ZZ) a = [x**(n - i)*a[i] for i in range(n + 1)] r = Add(*a) _, factors = factor_list(r) res = _choose_factor(factors, x, ex) return res expr = ((1 - cos(2*c*pi))/2)**S.Half res = _minpoly_compose(expr, x, QQ) return res raise NotAlgebraic("%s doesn't seem to be an algebraic element" % ex) def _minpoly_cos(ex, x): """ Returns the minimal polynomial of ``cos(ex)`` see http://mathworld.wolfram.com/TrigonometryAngles.html """ from sympy import sqrt c, a = ex.args[0].as_coeff_Mul() if a is pi: if c.is_rational: if c.p == 1: if c.q == 7: return 8*x**3 - 4*x**2 - 4*x + 1 if c.q == 9: return 8*x**3 - 6*x + 1 elif c.p == 2: q = sympify(c.q) if q.is_prime: s = _minpoly_sin(ex, x) return _mexpand(s.subs({x:sqrt((1 - x)/2)})) # for a = pi*p/q, cos(q*a) =T_q(cos(a)) = (-1)**p n = int(c.q) a = dup_chebyshevt(n, ZZ) a = [x**(n - i)*a[i] for i in range(n + 1)] r = Add(*a) - (-1)**c.p _, factors = factor_list(r) res = _choose_factor(factors, x, ex) return res raise NotAlgebraic("%s doesn't seem to be an algebraic element" % ex) def _minpoly_exp(ex, x): """ Returns the minimal polynomial of ``exp(ex)`` """ c, a = ex.args[0].as_coeff_Mul() q = sympify(c.q) if a == I*pi: if c.is_rational: if c.p == 1 or c.p == -1: if q == 3: return x**2 - x + 1 if q == 4: return x**4 + 1 if q == 6: return x**4 - x**2 + 1 if q == 8: return x**8 + 1 if q == 9: return x**6 - x**3 + 1 if q == 10: return x**8 - x**6 + x**4 - x**2 + 1 if q.is_prime: s = 0 for i in range(q): s += (-x)**i return s # x**(2*q) = product(factors) factors = [cyclotomic_poly(i, x) for i in divisors(2*q)] mp = _choose_factor(factors, x, ex) return mp else: raise NotAlgebraic("%s doesn't seem to be an algebraic element" % ex) raise NotAlgebraic("%s doesn't seem to be an algebraic element" % ex) def _minpoly_rootof(ex, x): """ Returns the minimal polynomial of a ``CRootOf`` object. """ p = ex.expr p = p.subs({ex.poly.gens[0]:x}) _, factors = factor_list(p, x) result = _choose_factor(factors, x, ex) return result def _minpoly_compose(ex, x, dom): """ Computes the minimal polynomial of an algebraic element using operations on minimal polynomials Examples ======== >>> from sympy import minimal_polynomial, sqrt, Rational >>> from sympy.abc import x, y >>> minimal_polynomial(sqrt(2) + 3*Rational(1, 3), x, compose=True) x**2 - 2*x - 1 >>> minimal_polynomial(sqrt(y) + 1/y, x, compose=True) x**2*y**2 - 2*x*y - y**3 + 1 """ if ex.is_Rational: return ex.q*x - ex.p if ex is I: _, factors = factor_list(x**2 + 1, x, domain=dom) return x**2 + 1 if len(factors) == 1 else x - I if hasattr(dom, 'symbols') and ex in dom.symbols: return x - ex if dom.is_QQ and _is_sum_surds(ex): # eliminate the square roots ex -= x while 1: ex1 = _separate_sq(ex) if ex1 is ex: return ex else: ex = ex1 if ex.is_Add: res = _minpoly_add(x, dom, *ex.args) elif ex.is_Mul: f = Factors(ex).factors r = sift(f.items(), lambda itx: itx[0].is_Rational and itx[1].is_Rational) if r[True] and dom == QQ: ex1 = Mul(*[bx**ex for bx, ex in r[False] + r[None]]) r1 = dict(r[True]) dens = [y.q for y in r1.values()] lcmdens = reduce(lcm, dens, 1) neg1 = S.NegativeOne expn1 = r1.pop(neg1, S.Zero) nums = [base**(y.p*lcmdens // y.q) for base, y in r1.items()] ex2 = Mul(*nums) mp1 = minimal_polynomial(ex1, x) # use the fact that in SymPy canonicalization products of integers # raised to rational powers are organized in relatively prime # bases, and that in ``base**(n/d)`` a perfect power is # simplified with the root # Powers of -1 have to be treated separately to preserve sign. mp2 = ex2.q*x**lcmdens - ex2.p*neg1**(expn1*lcmdens) ex2 = neg1**expn1 * ex2**Rational(1, lcmdens) res = _minpoly_op_algebraic_element(Mul, ex1, ex2, x, dom, mp1=mp1, mp2=mp2) else: res = _minpoly_mul(x, dom, *ex.args) elif ex.is_Pow: res = _minpoly_pow(ex.base, ex.exp, x, dom) elif ex.__class__ is sin: res = _minpoly_sin(ex, x) elif ex.__class__ is cos: res = _minpoly_cos(ex, x) elif ex.__class__ is exp: res = _minpoly_exp(ex, x) elif ex.__class__ is CRootOf: res = _minpoly_rootof(ex, x) else: raise NotAlgebraic("%s doesn't seem to be an algebraic element" % ex) return res @public def minimal_polynomial(ex, x=None, compose=True, polys=False, domain=None): """ Computes the minimal polynomial of an algebraic element. Parameters ========== ex : Expr Element or expression whose minimal polynomial is to be calculated. x : Symbol, optional Independent variable of the minimal polynomial compose : boolean, optional (default=True) Method to use for computing minimal polynomial. If ``compose=True`` (default) then ``_minpoly_compose`` is used, if ``compose=False`` then groebner bases are used. polys : boolean, optional (default=False) If ``True`` returns a ``Poly`` object else an ``Expr`` object. domain : Domain, optional Ground domain Notes ===== By default ``compose=True``, the minimal polynomial of the subexpressions of ``ex`` are computed, then the arithmetic operations on them are performed using the resultant and factorization. If ``compose=False``, a bottom-up algorithm is used with ``groebner``. The default algorithm stalls less frequently. If no ground domain is given, it will be generated automatically from the expression. Examples ======== >>> from sympy import minimal_polynomial, sqrt, solve, QQ >>> from sympy.abc import x, y >>> minimal_polynomial(sqrt(2), x) x**2 - 2 >>> minimal_polynomial(sqrt(2), x, domain=QQ.algebraic_field(sqrt(2))) x - sqrt(2) >>> minimal_polynomial(sqrt(2) + sqrt(3), x) x**4 - 10*x**2 + 1 >>> minimal_polynomial(solve(x**3 + x + 3)[0], x) x**3 + x + 3 >>> minimal_polynomial(sqrt(y), x) x**2 - y """ from sympy.polys.polytools import degree from sympy.polys.domains import FractionField from sympy.core.basic import preorder_traversal ex = sympify(ex) if ex.is_number: # not sure if it's always needed but try it for numbers (issue 8354) ex = _mexpand(ex, recursive=True) for expr in preorder_traversal(ex): if expr.is_AlgebraicNumber: compose = False break if x is not None: x, cls = sympify(x), Poly else: x, cls = Dummy('x'), PurePoly if not domain: if ex.free_symbols: domain = FractionField(QQ, list(ex.free_symbols)) else: domain = QQ if hasattr(domain, 'symbols') and x in domain.symbols: raise GeneratorsError("the variable %s is an element of the ground " "domain %s" % (x, domain)) if compose: result = _minpoly_compose(ex, x, domain) result = result.primitive()[1] c = result.coeff(x**degree(result, x)) if c.is_negative: result = expand_mul(-result) return cls(result, x, field=True) if polys else result.collect(x) if not domain.is_QQ: raise NotImplementedError("groebner method only works for QQ") result = _minpoly_groebner(ex, x, cls) return cls(result, x, field=True) if polys else result.collect(x) def _minpoly_groebner(ex, x, cls): """ Computes the minimal polynomial of an algebraic number using Groebner bases Examples ======== >>> from sympy import minimal_polynomial, sqrt, Rational >>> from sympy.abc import x >>> minimal_polynomial(sqrt(2) + 3*Rational(1, 3), x, compose=False) x**2 - 2*x - 1 """ from sympy.polys.polytools import degree from sympy.core.function import expand_multinomial generator = numbered_symbols('a', cls=Dummy) mapping, symbols = {}, {} def update_mapping(ex, exp, base=None): a = next(generator) symbols[ex] = a if base is not None: mapping[ex] = a**exp + base else: mapping[ex] = exp.as_expr(a) return a def bottom_up_scan(ex): if ex.is_Atom: if ex is S.ImaginaryUnit: if ex not in mapping: return update_mapping(ex, 2, 1) else: return symbols[ex] elif ex.is_Rational: return ex elif ex.is_Add: return Add(*[ bottom_up_scan(g) for g in ex.args ]) elif ex.is_Mul: return Mul(*[ bottom_up_scan(g) for g in ex.args ]) elif ex.is_Pow: if ex.exp.is_Rational: if ex.exp < 0 and ex.base.is_Add: coeff, terms = ex.base.as_coeff_add() elt, _ = primitive_element(terms, polys=True) alg = ex.base - coeff # XXX: turn this into eval() inverse = invert(elt.gen + coeff, elt).as_expr() base = inverse.subs(elt.gen, alg).expand() if ex.exp == -1: return bottom_up_scan(base) else: ex = base**(-ex.exp) if not ex.exp.is_Integer: base, exp = ( ex.base**ex.exp.p).expand(), Rational(1, ex.exp.q) else: base, exp = ex.base, ex.exp base = bottom_up_scan(base) expr = base**exp if expr not in mapping: return update_mapping(expr, 1/exp, -base) else: return symbols[expr] elif ex.is_AlgebraicNumber: if ex.root not in mapping: return update_mapping(ex.root, ex.minpoly) else: return symbols[ex.root] raise NotAlgebraic("%s doesn't seem to be an algebraic number" % ex) def simpler_inverse(ex): """ Returns True if it is more likely that the minimal polynomial algorithm works better with the inverse """ if ex.is_Pow: if (1/ex.exp).is_integer and ex.exp < 0: if ex.base.is_Add: return True if ex.is_Mul: hit = True for p in ex.args: if p.is_Add: return False if p.is_Pow: if p.base.is_Add and p.exp > 0: return False if hit: return True return False inverted = False ex = expand_multinomial(ex) if ex.is_AlgebraicNumber: return ex.minpoly.as_expr(x) elif ex.is_Rational: result = ex.q*x - ex.p else: inverted = simpler_inverse(ex) if inverted: ex = ex**-1 res = None if ex.is_Pow and (1/ex.exp).is_Integer: n = 1/ex.exp res = _minimal_polynomial_sq(ex.base, n, x) elif _is_sum_surds(ex): res = _minimal_polynomial_sq(ex, S.One, x) if res is not None: result = res if res is None: bus = bottom_up_scan(ex) F = [x - bus] + list(mapping.values()) G = groebner(F, list(symbols.values()) + [x], order='lex') _, factors = factor_list(G[-1]) # by construction G[-1] has root `ex` result = _choose_factor(factors, x, ex) if inverted: result = _invertx(result, x) if result.coeff(x**degree(result, x)) < 0: result = expand_mul(-result) return result minpoly = minimal_polynomial __all__.append('minpoly') def _coeffs_generator(n): """Generate coefficients for `primitive_element()`. """ for coeffs in variations([1, -1, 2, -2, 3, -3], n, repetition=True): # Two linear combinations with coeffs of opposite signs are # opposites of each other. Hence it suffices to test only one. if coeffs[0] > 0: yield list(coeffs) @public def primitive_element(extension, x=None, **args): """Construct a common number field for all extensions. """ if not extension: raise ValueError("can't compute primitive element for empty extension") if x is not None: x, cls = sympify(x), Poly else: x, cls = Dummy('x'), PurePoly if not args.get('ex', False): gen, coeffs = extension[0], [1] # XXX when minimal_polynomial is extended to work # with AlgebraicNumbers this test can be removed if isinstance(gen, AlgebraicNumber): g = gen.minpoly.replace(x) else: g = minimal_polynomial(gen, x, polys=True) for ext in extension[1:]: _, factors = factor_list(g, extension=ext) g = _choose_factor(factors, x, gen) s, _, g = g.sqf_norm() gen += s*ext coeffs.append(s) if not args.get('polys', False): return g.as_expr(), coeffs else: return cls(g), coeffs generator = numbered_symbols('y', cls=Dummy) F, Y = [], [] for ext in extension: y = next(generator) if ext.is_Poly: if ext.is_univariate: f = ext.as_expr(y) else: raise ValueError("expected minimal polynomial, got %s" % ext) else: f = minpoly(ext, y) F.append(f) Y.append(y) coeffs_generator = args.get('coeffs', _coeffs_generator) for coeffs in coeffs_generator(len(Y)): f = x - sum([ c*y for c, y in zip(coeffs, Y)]) G = groebner(F + [f], Y + [x], order='lex', field=True) H, g = G[:-1], cls(G[-1], x, domain='QQ') for i, (h, y) in enumerate(zip(H, Y)): try: H[i] = Poly(y - h, x, domain='QQ').all_coeffs() # XXX: composite=False except CoercionFailed: # pragma: no cover break # G is not a triangular set else: break else: # pragma: no cover raise RuntimeError("run out of coefficient configurations") _, g = g.clear_denoms() if not args.get('polys', False): return g.as_expr(), coeffs, H else: return g, coeffs, H def is_isomorphism_possible(a, b): """Returns `True` if there is a chance for isomorphism. """ n = a.minpoly.degree() m = b.minpoly.degree() if m % n != 0: return False if n == m: return True da = a.minpoly.discriminant() db = b.minpoly.discriminant() i, k, half = 1, m//n, db//2 while True: p = sieve[i] P = p**k if P > half: break if ((da % p) % 2) and not (db % P): return False i += 1 return True def field_isomorphism_pslq(a, b): """Construct field isomorphism using PSLQ algorithm. """ if not a.root.is_real or not b.root.is_real: raise NotImplementedError("PSLQ doesn't support complex coefficients") f = a.minpoly g = b.minpoly.replace(f.gen) n, m, prev = 100, b.minpoly.degree(), None for i in range(1, 5): A = a.root.evalf(n) B = b.root.evalf(n) basis = [1, B] + [ B**i for i in range(2, m) ] + [A] dps, mp.dps = mp.dps, n coeffs = pslq(basis, maxcoeff=int(1e10), maxsteps=1000) mp.dps = dps if coeffs is None: break if coeffs != prev: prev = coeffs else: break coeffs = [S(c)/coeffs[-1] for c in coeffs[:-1]] while not coeffs[-1]: coeffs.pop() coeffs = list(reversed(coeffs)) h = Poly(coeffs, f.gen, domain='QQ') if f.compose(h).rem(g).is_zero: d, approx = len(coeffs) - 1, 0 for i, coeff in enumerate(coeffs): approx += coeff*B**(d - i) if A*approx < 0: return [ -c for c in coeffs ] else: return coeffs elif f.compose(-h).rem(g).is_zero: return [ -c for c in coeffs ] else: n *= 2 return None def field_isomorphism_factor(a, b): """Construct field isomorphism via factorization. """ _, factors = factor_list(a.minpoly, extension=b) for f, _ in factors: if f.degree() == 1: coeffs = f.rep.TC().to_sympy_list() d, terms = len(coeffs) - 1, [] for i, coeff in enumerate(coeffs): terms.append(coeff*b.root**(d - i)) root = Add(*terms) if (a.root - root).evalf(chop=True) == 0: return coeffs if (a.root + root).evalf(chop=True) == 0: return [ -c for c in coeffs ] else: return None @public def field_isomorphism(a, b, **args): """Construct an isomorphism between two number fields. """ a, b = sympify(a), sympify(b) if not a.is_AlgebraicNumber: a = AlgebraicNumber(a) if not b.is_AlgebraicNumber: b = AlgebraicNumber(b) if a == b: return a.coeffs() n = a.minpoly.degree() m = b.minpoly.degree() if n == 1: return [a.root] if m % n != 0: return None if args.get('fast', True): try: result = field_isomorphism_pslq(a, b) if result is not None: return result except NotImplementedError: pass return field_isomorphism_factor(a, b) @public def to_number_field(extension, theta=None, **args): """Express `extension` in the field generated by `theta`. """ gen = args.get('gen') if hasattr(extension, '__iter__'): extension = list(extension) else: extension = [extension] if len(extension) == 1 and type(extension[0]) is tuple: return AlgebraicNumber(extension[0]) minpoly, coeffs = primitive_element(extension, gen, polys=True) root = sum([ coeff*ext for coeff, ext in zip(coeffs, extension) ]) if theta is None: return AlgebraicNumber((minpoly, root)) else: theta = sympify(theta) if not theta.is_AlgebraicNumber: theta = AlgebraicNumber(theta, gen=gen) coeffs = field_isomorphism(root, theta) if coeffs is not None: return AlgebraicNumber(theta, coeffs) else: raise IsomorphismFailed( "%s is not in a subfield of %s" % (root, theta.root)) class IntervalPrinter(LambdaPrinter): """Use ``lambda`` printer but print numbers as ``mpi`` intervals. """ def _print_Integer(self, expr): return "mpi('%s')" % super(IntervalPrinter, self)._print_Integer(expr) def _print_Rational(self, expr): return "mpi('%s')" % super(IntervalPrinter, self)._print_Rational(expr) def _print_Pow(self, expr): return super(IntervalPrinter, self)._print_Pow(expr, rational=True) @public def isolate(alg, eps=None, fast=False): """Give a rational isolating interval for an algebraic number. """ alg = sympify(alg) if alg.is_Rational: return (alg, alg) elif not alg.is_real: raise NotImplementedError( "complex algebraic numbers are not supported") func = lambdify((), alg, modules="mpmath", printer=IntervalPrinter()) poly = minpoly(alg, polys=True) intervals = poly.intervals(sqf=True) dps, done = mp.dps, False try: while not done: alg = func() for a, b in intervals: if a <= alg.a and alg.b <= b: done = True break else: mp.dps *= 2 finally: mp.dps = dps if eps is not None: a, b = poly.refine_root(a, b, eps=eps, fast=fast) return (a, b)

5dfb18a1f688f3f7bf417a175597e1c2a8c4d90a138e38e1ab80ee38c84a7019

from __future__ import print_function, division from sympy.core import S from sympy.polys import Poly def dispersionset(p, q=None, *gens, **args): r"""Compute the *dispersion set* of two polynomials. For two polynomials `f(x)` and `g(x)` with `\deg f > 0` and `\deg g > 0` the dispersion set `\operatorname{J}(f, g)` is defined as: .. math:: \operatorname{J}(f, g) & := \{a \in \mathbb{N}_0 | \gcd(f(x), g(x+a)) \neq 1\} \\ & = \{a \in \mathbb{N}_0 | \deg \gcd(f(x), g(x+a)) \geq 1\} For a single polynomial one defines `\operatorname{J}(f) := \operatorname{J}(f, f)`. Examples ======== >>> from sympy import poly >>> from sympy.polys.dispersion import dispersion, dispersionset >>> from sympy.abc import x Dispersion set and dispersion of a simple polynomial: >>> fp = poly((x - 3)*(x + 3), x) >>> sorted(dispersionset(fp)) [0, 6] >>> dispersion(fp) 6 Note that the definition of the dispersion is not symmetric: >>> fp = poly(x**4 - 3*x**2 + 1, x) >>> gp = fp.shift(-3) >>> sorted(dispersionset(fp, gp)) [2, 3, 4] >>> dispersion(fp, gp) 4 >>> sorted(dispersionset(gp, fp)) [] >>> dispersion(gp, fp) -oo Computing the dispersion also works over field extensions: >>> from sympy import sqrt >>> fp = poly(x**2 + sqrt(5)*x - 1, x, domain='QQ<sqrt(5)>') >>> gp = poly(x**2 + (2 + sqrt(5))*x + sqrt(5), x, domain='QQ<sqrt(5)>') >>> sorted(dispersionset(fp, gp)) [2] >>> sorted(dispersionset(gp, fp)) [1, 4] We can even perform the computations for polynomials having symbolic coefficients: >>> from sympy.abc import a >>> fp = poly(4*x**4 + (4*a + 8)*x**3 + (a**2 + 6*a + 4)*x**2 + (a**2 + 2*a)*x, x) >>> sorted(dispersionset(fp)) [0, 1] See Also ======== dispersion References ========== .. [1] [ManWright94]_ .. [2] [Koepf98]_ .. [3] [Abramov71]_ .. [4] [Man93]_ """ # Check for valid input same = False if q is not None else True if same: q = p p = Poly(p, *gens, **args) q = Poly(q, *gens, **args) if not p.is_univariate or not q.is_univariate: raise ValueError("Polynomials need to be univariate") # The generator if not p.gen == q.gen: raise ValueError("Polynomials must have the same generator") gen = p.gen # We define the dispersion of constant polynomials to be zero if p.degree() < 1 or q.degree() < 1: return set([0]) # Factor p and q over the rationals fp = p.factor_list() fq = q.factor_list() if not same else fp # Iterate over all pairs of factors J = set([]) for s, unused in fp[1]: for t, unused in fq[1]: m = s.degree() n = t.degree() if n != m: continue an = s.LC() bn = t.LC() if not (an - bn).is_zero: continue # Note that the roles of `s` and `t` below are switched # w.r.t. the original paper. This is for consistency # with the description in the book of W. Koepf. anm1 = s.coeff_monomial(gen**(m-1)) bnm1 = t.coeff_monomial(gen**(n-1)) alpha = (anm1 - bnm1) / S(n*bn) if not alpha.is_integer: continue if alpha < 0 or alpha in J: continue if n > 1 and not (s - t.shift(alpha)).is_zero: continue J.add(alpha) return J def dispersion(p, q=None, *gens, **args): r"""Compute the *dispersion* of polynomials. For two polynomials `f(x)` and `g(x)` with `\deg f > 0` and `\deg g > 0` the dispersion `\operatorname{dis}(f, g)` is defined as: .. math:: \operatorname{dis}(f, g) & := \max\{ J(f,g) \cup \{0\} \} \\ & = \max\{ \{a \in \mathbb{N} | \gcd(f(x), g(x+a)) \neq 1\} \cup \{0\} \} and for a single polynomial `\operatorname{dis}(f) := \operatorname{dis}(f, f)`. Note that we make the definition `\max\{\} := -\infty`. Examples ======== >>> from sympy import poly >>> from sympy.polys.dispersion import dispersion, dispersionset >>> from sympy.abc import x Dispersion set and dispersion of a simple polynomial: >>> fp = poly((x - 3)*(x + 3), x) >>> sorted(dispersionset(fp)) [0, 6] >>> dispersion(fp) 6 Note that the definition of the dispersion is not symmetric: >>> fp = poly(x**4 - 3*x**2 + 1, x) >>> gp = fp.shift(-3) >>> sorted(dispersionset(fp, gp)) [2, 3, 4] >>> dispersion(fp, gp) 4 >>> sorted(dispersionset(gp, fp)) [] >>> dispersion(gp, fp) -oo The maximum of an empty set is defined to be `-\infty` as seen in this example. Computing the dispersion also works over field extensions: >>> from sympy import sqrt >>> fp = poly(x**2 + sqrt(5)*x - 1, x, domain='QQ<sqrt(5)>') >>> gp = poly(x**2 + (2 + sqrt(5))*x + sqrt(5), x, domain='QQ<sqrt(5)>') >>> sorted(dispersionset(fp, gp)) [2] >>> sorted(dispersionset(gp, fp)) [1, 4] We can even perform the computations for polynomials having symbolic coefficients: >>> from sympy.abc import a >>> fp = poly(4*x**4 + (4*a + 8)*x**3 + (a**2 + 6*a + 4)*x**2 + (a**2 + 2*a)*x, x) >>> sorted(dispersionset(fp)) [0, 1] See Also ======== dispersionset References ========== .. [1] [ManWright94]_ .. [2] [Koepf98]_ .. [3] [Abramov71]_ .. [4] [Man93]_ """ J = dispersionset(p, q, *gens, **args) if not J: # Definition for maximum of empty set j = S.NegativeInfinity else: j = max(J) return j

8942501bff4bbf9fd07f7b2b3a43162be0c114262438228c91b1a920983987a0

"""Euclidean algorithms, GCDs, LCMs and polynomial remainder sequences. """ from __future__ import print_function, division from sympy.core.compatibility import range from sympy.ntheory import nextprime from sympy.polys.densearith import ( dup_sub_mul, dup_neg, dmp_neg, dmp_add, dmp_sub, dup_mul, dmp_mul, dmp_pow, dup_div, dmp_div, dup_rem, dup_quo, dmp_quo, dup_prem, dmp_prem, dup_mul_ground, dmp_mul_ground, dmp_mul_term, dup_quo_ground, dmp_quo_ground, dup_max_norm, dmp_max_norm) from sympy.polys.densebasic import ( dup_strip, dmp_raise, dmp_zero, dmp_one, dmp_ground, dmp_one_p, dmp_zero_p, dmp_zeros, dup_degree, dmp_degree, dmp_degree_in, dup_LC, dmp_LC, dmp_ground_LC, dmp_multi_deflate, dmp_inflate, dup_convert, dmp_convert, dmp_apply_pairs) from sympy.polys.densetools import ( dup_clear_denoms, dmp_clear_denoms, dup_diff, dmp_diff, dup_eval, dmp_eval, dmp_eval_in, dup_trunc, dmp_ground_trunc, dup_monic, dmp_ground_monic, dup_primitive, dmp_ground_primitive, dup_extract, dmp_ground_extract) from sympy.polys.galoistools import ( gf_int, gf_crt) from sympy.polys.polyconfig import query from sympy.polys.polyerrors import ( MultivariatePolynomialError, HeuristicGCDFailed, HomomorphismFailed, NotInvertible, DomainError) def dup_half_gcdex(f, g, K): """ Half extended Euclidean algorithm in `F[x]`. Returns ``(s, h)`` such that ``h = gcd(f, g)`` and ``s*f = h (mod g)``. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x = ring("x", QQ) >>> f = x**4 - 2*x**3 - 6*x**2 + 12*x + 15 >>> g = x**3 + x**2 - 4*x - 4 >>> R.dup_half_gcdex(f, g) (-1/5*x + 3/5, x + 1) """ if not K.is_Field: raise DomainError("can't compute half extended GCD over %s" % K) a, b = [K.one], [] while g: q, r = dup_div(f, g, K) f, g = g, r a, b = b, dup_sub_mul(a, q, b, K) a = dup_quo_ground(a, dup_LC(f, K), K) f = dup_monic(f, K) return a, f def dmp_half_gcdex(f, g, u, K): """ Half extended Euclidean algorithm in `F[X]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) """ if not u: return dup_half_gcdex(f, g, K) else: raise MultivariatePolynomialError(f, g) def dup_gcdex(f, g, K): """ Extended Euclidean algorithm in `F[x]`. Returns ``(s, t, h)`` such that ``h = gcd(f, g)`` and ``s*f + t*g = h``. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x = ring("x", QQ) >>> f = x**4 - 2*x**3 - 6*x**2 + 12*x + 15 >>> g = x**3 + x**2 - 4*x - 4 >>> R.dup_gcdex(f, g) (-1/5*x + 3/5, 1/5*x**2 - 6/5*x + 2, x + 1) """ s, h = dup_half_gcdex(f, g, K) F = dup_sub_mul(h, s, f, K) t = dup_quo(F, g, K) return s, t, h def dmp_gcdex(f, g, u, K): """ Extended Euclidean algorithm in `F[X]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) """ if not u: return dup_gcdex(f, g, K) else: raise MultivariatePolynomialError(f, g) def dup_invert(f, g, K): """ Compute multiplicative inverse of `f` modulo `g` in `F[x]`. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x = ring("x", QQ) >>> f = x**2 - 1 >>> g = 2*x - 1 >>> h = x - 1 >>> R.dup_invert(f, g) -4/3 >>> R.dup_invert(f, h) Traceback (most recent call last): ... NotInvertible: zero divisor """ s, h = dup_half_gcdex(f, g, K) if h == [K.one]: return dup_rem(s, g, K) else: raise NotInvertible("zero divisor") def dmp_invert(f, g, u, K): """ Compute multiplicative inverse of `f` modulo `g` in `F[X]`. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x = ring("x", QQ) """ if not u: return dup_invert(f, g, K) else: raise MultivariatePolynomialError(f, g) def dup_euclidean_prs(f, g, K): """ Euclidean polynomial remainder sequence (PRS) in `K[x]`. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x = ring("x", QQ) >>> f = x**8 + x**6 - 3*x**4 - 3*x**3 + 8*x**2 + 2*x - 5 >>> g = 3*x**6 + 5*x**4 - 4*x**2 - 9*x + 21 >>> prs = R.dup_euclidean_prs(f, g) >>> prs[0] x**8 + x**6 - 3*x**4 - 3*x**3 + 8*x**2 + 2*x - 5 >>> prs[1] 3*x**6 + 5*x**4 - 4*x**2 - 9*x + 21 >>> prs[2] -5/9*x**4 + 1/9*x**2 - 1/3 >>> prs[3] -117/25*x**2 - 9*x + 441/25 >>> prs[4] 233150/19773*x - 102500/6591 >>> prs[5] -1288744821/543589225 """ prs = [f, g] h = dup_rem(f, g, K) while h: prs.append(h) f, g = g, h h = dup_rem(f, g, K) return prs def dmp_euclidean_prs(f, g, u, K): """ Euclidean polynomial remainder sequence (PRS) in `K[X]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) """ if not u: return dup_euclidean_prs(f, g, K) else: raise MultivariatePolynomialError(f, g) def dup_primitive_prs(f, g, K): """ Primitive polynomial remainder sequence (PRS) in `K[x]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> f = x**8 + x**6 - 3*x**4 - 3*x**3 + 8*x**2 + 2*x - 5 >>> g = 3*x**6 + 5*x**4 - 4*x**2 - 9*x + 21 >>> prs = R.dup_primitive_prs(f, g) >>> prs[0] x**8 + x**6 - 3*x**4 - 3*x**3 + 8*x**2 + 2*x - 5 >>> prs[1] 3*x**6 + 5*x**4 - 4*x**2 - 9*x + 21 >>> prs[2] -5*x**4 + x**2 - 3 >>> prs[3] 13*x**2 + 25*x - 49 >>> prs[4] 4663*x - 6150 >>> prs[5] 1 """ prs = [f, g] _, h = dup_primitive(dup_prem(f, g, K), K) while h: prs.append(h) f, g = g, h _, h = dup_primitive(dup_prem(f, g, K), K) return prs def dmp_primitive_prs(f, g, u, K): """ Primitive polynomial remainder sequence (PRS) in `K[X]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) """ if not u: return dup_primitive_prs(f, g, K) else: raise MultivariatePolynomialError(f, g) def dup_inner_subresultants(f, g, K): """ Subresultant PRS algorithm in `K[x]`. Computes the subresultant polynomial remainder sequence (PRS) and the non-zero scalar subresultants of `f` and `g`. By [1] Thm. 3, these are the constants '-c' (- to optimize computation of sign). The first subdeterminant is set to 1 by convention to match the polynomial and the scalar subdeterminants. If 'deg(f) < deg(g)', the subresultants of '(g,f)' are computed. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_inner_subresultants(x**2 + 1, x**2 - 1) ([x**2 + 1, x**2 - 1, -2], [1, 1, 4]) References ========== .. [1] W.S. Brown, The Subresultant PRS Algorithm. ACM Transaction of Mathematical Software 4 (1978) 237-249 """ n = dup_degree(f) m = dup_degree(g) if n < m: f, g = g, f n, m = m, n if not f: return [], [] if not g: return [f], [K.one] R = [f, g] d = n - m b = (-K.one)**(d + 1) h = dup_prem(f, g, K) h = dup_mul_ground(h, b, K) lc = dup_LC(g, K) c = lc**d # Conventional first scalar subdeterminant is 1 S = [K.one, c] c = -c while h: k = dup_degree(h) R.append(h) f, g, m, d = g, h, k, m - k b = -lc * c**d h = dup_prem(f, g, K) h = dup_quo_ground(h, b, K) lc = dup_LC(g, K) if d > 1: # abnormal case q = c**(d - 1) c = K.quo((-lc)**d, q) else: c = -lc S.append(-c) return R, S def dup_subresultants(f, g, K): """ Computes subresultant PRS of two polynomials in `K[x]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_subresultants(x**2 + 1, x**2 - 1) [x**2 + 1, x**2 - 1, -2] """ return dup_inner_subresultants(f, g, K)[0] def dup_prs_resultant(f, g, K): """ Resultant algorithm in `K[x]` using subresultant PRS. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_prs_resultant(x**2 + 1, x**2 - 1) (4, [x**2 + 1, x**2 - 1, -2]) """ if not f or not g: return (K.zero, []) R, S = dup_inner_subresultants(f, g, K) if dup_degree(R[-1]) > 0: return (K.zero, R) return S[-1], R def dup_resultant(f, g, K, includePRS=False): """ Computes resultant of two polynomials in `K[x]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_resultant(x**2 + 1, x**2 - 1) 4 """ if includePRS: return dup_prs_resultant(f, g, K) return dup_prs_resultant(f, g, K)[0] def dmp_inner_subresultants(f, g, u, K): """ Subresultant PRS algorithm in `K[X]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = 3*x**2*y - y**3 - 4 >>> g = x**2 + x*y**3 - 9 >>> a = 3*x*y**4 + y**3 - 27*y + 4 >>> b = -3*y**10 - 12*y**7 + y**6 - 54*y**4 + 8*y**3 + 729*y**2 - 216*y + 16 >>> prs = [f, g, a, b] >>> sres = [[1], [1], [3, 0, 0, 0, 0], [-3, 0, 0, -12, 1, 0, -54, 8, 729, -216, 16]] >>> R.dmp_inner_subresultants(f, g) == (prs, sres) True """ if not u: return dup_inner_subresultants(f, g, K) n = dmp_degree(f, u) m = dmp_degree(g, u) if n < m: f, g = g, f n, m = m, n if dmp_zero_p(f, u): return [], [] v = u - 1 if dmp_zero_p(g, u): return [f], [dmp_ground(K.one, v)] R = [f, g] d = n - m b = dmp_pow(dmp_ground(-K.one, v), d + 1, v, K) h = dmp_prem(f, g, u, K) h = dmp_mul_term(h, b, 0, u, K) lc = dmp_LC(g, K) c = dmp_pow(lc, d, v, K) S = [dmp_ground(K.one, v), c] c = dmp_neg(c, v, K) while not dmp_zero_p(h, u): k = dmp_degree(h, u) R.append(h) f, g, m, d = g, h, k, m - k b = dmp_mul(dmp_neg(lc, v, K), dmp_pow(c, d, v, K), v, K) h = dmp_prem(f, g, u, K) h = [ dmp_quo(ch, b, v, K) for ch in h ] lc = dmp_LC(g, K) if d > 1: p = dmp_pow(dmp_neg(lc, v, K), d, v, K) q = dmp_pow(c, d - 1, v, K) c = dmp_quo(p, q, v, K) else: c = dmp_neg(lc, v, K) S.append(dmp_neg(c, v, K)) return R, S def dmp_subresultants(f, g, u, K): """ Computes subresultant PRS of two polynomials in `K[X]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = 3*x**2*y - y**3 - 4 >>> g = x**2 + x*y**3 - 9 >>> a = 3*x*y**4 + y**3 - 27*y + 4 >>> b = -3*y**10 - 12*y**7 + y**6 - 54*y**4 + 8*y**3 + 729*y**2 - 216*y + 16 >>> R.dmp_subresultants(f, g) == [f, g, a, b] True """ return dmp_inner_subresultants(f, g, u, K)[0] def dmp_prs_resultant(f, g, u, K): """ Resultant algorithm in `K[X]` using subresultant PRS. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = 3*x**2*y - y**3 - 4 >>> g = x**2 + x*y**3 - 9 >>> a = 3*x*y**4 + y**3 - 27*y + 4 >>> b = -3*y**10 - 12*y**7 + y**6 - 54*y**4 + 8*y**3 + 729*y**2 - 216*y + 16 >>> res, prs = R.dmp_prs_resultant(f, g) >>> res == b # resultant has n-1 variables False >>> res == b.drop(x) True >>> prs == [f, g, a, b] True """ if not u: return dup_prs_resultant(f, g, K) if dmp_zero_p(f, u) or dmp_zero_p(g, u): return (dmp_zero(u - 1), []) R, S = dmp_inner_subresultants(f, g, u, K) if dmp_degree(R[-1], u) > 0: return (dmp_zero(u - 1), R) return S[-1], R def dmp_zz_modular_resultant(f, g, p, u, K): """ Compute resultant of `f` and `g` modulo a prime `p`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = x + y + 2 >>> g = 2*x*y + x + 3 >>> R.dmp_zz_modular_resultant(f, g, 5) -2*y**2 + 1 """ if not u: return gf_int(dup_prs_resultant(f, g, K)[0] % p, p) v = u - 1 n = dmp_degree(f, u) m = dmp_degree(g, u) N = dmp_degree_in(f, 1, u) M = dmp_degree_in(g, 1, u) B = n*M + m*N D, a = [K.one], -K.one r = dmp_zero(v) while dup_degree(D) <= B: while True: a += K.one if a == p: raise HomomorphismFailed('no luck') F = dmp_eval_in(f, gf_int(a, p), 1, u, K) if dmp_degree(F, v) == n: G = dmp_eval_in(g, gf_int(a, p), 1, u, K) if dmp_degree(G, v) == m: break R = dmp_zz_modular_resultant(F, G, p, v, K) e = dmp_eval(r, a, v, K) if not v: R = dup_strip([R]) e = dup_strip([e]) else: R = [R] e = [e] d = K.invert(dup_eval(D, a, K), p) d = dup_mul_ground(D, d, K) d = dmp_raise(d, v, 0, K) c = dmp_mul(d, dmp_sub(R, e, v, K), v, K) r = dmp_add(r, c, v, K) r = dmp_ground_trunc(r, p, v, K) D = dup_mul(D, [K.one, -a], K) D = dup_trunc(D, p, K) return r def _collins_crt(r, R, P, p, K): """Wrapper of CRT for Collins's resultant algorithm. """ return gf_int(gf_crt([r, R], [P, p], K), P*p) def dmp_zz_collins_resultant(f, g, u, K): """ Collins's modular resultant algorithm in `Z[X]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = x + y + 2 >>> g = 2*x*y + x + 3 >>> R.dmp_zz_collins_resultant(f, g) -2*y**2 - 5*y + 1 """ n = dmp_degree(f, u) m = dmp_degree(g, u) if n < 0 or m < 0: return dmp_zero(u - 1) A = dmp_max_norm(f, u, K) B = dmp_max_norm(g, u, K) a = dmp_ground_LC(f, u, K) b = dmp_ground_LC(g, u, K) v = u - 1 B = K(2)*K.factorial(K(n + m))*A**m*B**n r, p, P = dmp_zero(v), K.one, K.one while P <= B: p = K(nextprime(p)) while not (a % p) or not (b % p): p = K(nextprime(p)) F = dmp_ground_trunc(f, p, u, K) G = dmp_ground_trunc(g, p, u, K) try: R = dmp_zz_modular_resultant(F, G, p, u, K) except HomomorphismFailed: continue if K.is_one(P): r = R else: r = dmp_apply_pairs(r, R, _collins_crt, (P, p, K), v, K) P *= p return r def dmp_qq_collins_resultant(f, g, u, K0): """ Collins's modular resultant algorithm in `Q[X]`. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x,y = ring("x,y", QQ) >>> f = QQ(1,2)*x + y + QQ(2,3) >>> g = 2*x*y + x + 3 >>> R.dmp_qq_collins_resultant(f, g) -2*y**2 - 7/3*y + 5/6 """ n = dmp_degree(f, u) m = dmp_degree(g, u) if n < 0 or m < 0: return dmp_zero(u - 1) K1 = K0.get_ring() cf, f = dmp_clear_denoms(f, u, K0, K1) cg, g = dmp_clear_denoms(g, u, K0, K1) f = dmp_convert(f, u, K0, K1) g = dmp_convert(g, u, K0, K1) r = dmp_zz_collins_resultant(f, g, u, K1) r = dmp_convert(r, u - 1, K1, K0) c = K0.convert(cf**m * cg**n, K1) return dmp_quo_ground(r, c, u - 1, K0) def dmp_resultant(f, g, u, K, includePRS=False): """ Computes resultant of two polynomials in `K[X]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> f = 3*x**2*y - y**3 - 4 >>> g = x**2 + x*y**3 - 9 >>> R.dmp_resultant(f, g) -3*y**10 - 12*y**7 + y**6 - 54*y**4 + 8*y**3 + 729*y**2 - 216*y + 16 """ if not u: return dup_resultant(f, g, K, includePRS=includePRS) if includePRS: return dmp_prs_resultant(f, g, u, K) if K.is_Field: if K.is_QQ and query('USE_COLLINS_RESULTANT'): return dmp_qq_collins_resultant(f, g, u, K) else: if K.is_ZZ and query('USE_COLLINS_RESULTANT'): return dmp_zz_collins_resultant(f, g, u, K) return dmp_prs_resultant(f, g, u, K)[0] def dup_discriminant(f, K): """ Computes discriminant of a polynomial in `K[x]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_discriminant(x**2 + 2*x + 3) -8 """ d = dup_degree(f) if d <= 0: return K.zero else: s = (-1)**((d*(d - 1)) // 2) c = dup_LC(f, K) r = dup_resultant(f, dup_diff(f, 1, K), K) return K.quo(r, c*K(s)) def dmp_discriminant(f, u, K): """ Computes discriminant of a polynomial in `K[X]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y,z,t = ring("x,y,z,t", ZZ) >>> R.dmp_discriminant(x**2*y + x*z + t) -4*y*t + z**2 """ if not u: return dup_discriminant(f, K) d, v = dmp_degree(f, u), u - 1 if d <= 0: return dmp_zero(v) else: s = (-1)**((d*(d - 1)) // 2) c = dmp_LC(f, K) r = dmp_resultant(f, dmp_diff(f, 1, u, K), u, K) c = dmp_mul_ground(c, K(s), v, K) return dmp_quo(r, c, v, K) def _dup_rr_trivial_gcd(f, g, K): """Handle trivial cases in GCD algorithm over a ring. """ if not (f or g): return [], [], [] elif not f: if K.is_nonnegative(dup_LC(g, K)): return g, [], [K.one] else: return dup_neg(g, K), [], [-K.one] elif not g: if K.is_nonnegative(dup_LC(f, K)): return f, [K.one], [] else: return dup_neg(f, K), [-K.one], [] return None def _dup_ff_trivial_gcd(f, g, K): """Handle trivial cases in GCD algorithm over a field. """ if not (f or g): return [], [], [] elif not f: return dup_monic(g, K), [], [dup_LC(g, K)] elif not g: return dup_monic(f, K), [dup_LC(f, K)], [] else: return None def _dmp_rr_trivial_gcd(f, g, u, K): """Handle trivial cases in GCD algorithm over a ring. """ zero_f = dmp_zero_p(f, u) zero_g = dmp_zero_p(g, u) if_contain_one = dmp_one_p(f, u, K) or dmp_one_p(g, u, K) if zero_f and zero_g: return tuple(dmp_zeros(3, u, K)) elif zero_f: if K.is_nonnegative(dmp_ground_LC(g, u, K)): return g, dmp_zero(u), dmp_one(u, K) else: return dmp_neg(g, u, K), dmp_zero(u), dmp_ground(-K.one, u) elif zero_g: if K.is_nonnegative(dmp_ground_LC(f, u, K)): return f, dmp_one(u, K), dmp_zero(u) else: return dmp_neg(f, u, K), dmp_ground(-K.one, u), dmp_zero(u) elif if_contain_one: return dmp_one(u, K), f, g elif query('USE_SIMPLIFY_GCD'): return _dmp_simplify_gcd(f, g, u, K) else: return None def _dmp_ff_trivial_gcd(f, g, u, K): """Handle trivial cases in GCD algorithm over a field. """ zero_f = dmp_zero_p(f, u) zero_g = dmp_zero_p(g, u) if zero_f and zero_g: return tuple(dmp_zeros(3, u, K)) elif zero_f: return (dmp_ground_monic(g, u, K), dmp_zero(u), dmp_ground(dmp_ground_LC(g, u, K), u)) elif zero_g: return (dmp_ground_monic(f, u, K), dmp_ground(dmp_ground_LC(f, u, K), u), dmp_zero(u)) elif query('USE_SIMPLIFY_GCD'): return _dmp_simplify_gcd(f, g, u, K) else: return None def _dmp_simplify_gcd(f, g, u, K): """Try to eliminate `x_0` from GCD computation in `K[X]`. """ df = dmp_degree(f, u) dg = dmp_degree(g, u) if df > 0 and dg > 0: return None if not (df or dg): F = dmp_LC(f, K) G = dmp_LC(g, K) else: if not df: F = dmp_LC(f, K) G = dmp_content(g, u, K) else: F = dmp_content(f, u, K) G = dmp_LC(g, K) v = u - 1 h = dmp_gcd(F, G, v, K) cff = [ dmp_quo(cf, h, v, K) for cf in f ] cfg = [ dmp_quo(cg, h, v, K) for cg in g ] return [h], cff, cfg def dup_rr_prs_gcd(f, g, K): """ Computes polynomial GCD using subresultants over a ring. Returns ``(h, cff, cfg)`` such that ``a = gcd(f, g)``, ``cff = quo(f, h)``, and ``cfg = quo(g, h)``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_rr_prs_gcd(x**2 - 1, x**2 - 3*x + 2) (x - 1, x + 1, x - 2) """ result = _dup_rr_trivial_gcd(f, g, K) if result is not None: return result fc, F = dup_primitive(f, K) gc, G = dup_primitive(g, K) c = K.gcd(fc, gc) h = dup_subresultants(F, G, K)[-1] _, h = dup_primitive(h, K) if K.is_negative(dup_LC(h, K)): c = -c h = dup_mul_ground(h, c, K) cff = dup_quo(f, h, K) cfg = dup_quo(g, h, K) return h, cff, cfg def dup_ff_prs_gcd(f, g, K): """ Computes polynomial GCD using subresultants over a field. Returns ``(h, cff, cfg)`` such that ``a = gcd(f, g)``, ``cff = quo(f, h)``, and ``cfg = quo(g, h)``. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x = ring("x", QQ) >>> R.dup_ff_prs_gcd(x**2 - 1, x**2 - 3*x + 2) (x - 1, x + 1, x - 2) """ result = _dup_ff_trivial_gcd(f, g, K) if result is not None: return result h = dup_subresultants(f, g, K)[-1] h = dup_monic(h, K) cff = dup_quo(f, h, K) cfg = dup_quo(g, h, K) return h, cff, cfg def dmp_rr_prs_gcd(f, g, u, K): """ Computes polynomial GCD using subresultants over a ring. Returns ``(h, cff, cfg)`` such that ``a = gcd(f, g)``, ``cff = quo(f, h)``, and ``cfg = quo(g, h)``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y, = ring("x,y", ZZ) >>> f = x**2 + 2*x*y + y**2 >>> g = x**2 + x*y >>> R.dmp_rr_prs_gcd(f, g) (x + y, x + y, x) """ if not u: return dup_rr_prs_gcd(f, g, K) result = _dmp_rr_trivial_gcd(f, g, u, K) if result is not None: return result fc, F = dmp_primitive(f, u, K) gc, G = dmp_primitive(g, u, K) h = dmp_subresultants(F, G, u, K)[-1] c, _, _ = dmp_rr_prs_gcd(fc, gc, u - 1, K) if K.is_negative(dmp_ground_LC(h, u, K)): h = dmp_neg(h, u, K) _, h = dmp_primitive(h, u, K) h = dmp_mul_term(h, c, 0, u, K) cff = dmp_quo(f, h, u, K) cfg = dmp_quo(g, h, u, K) return h, cff, cfg def dmp_ff_prs_gcd(f, g, u, K): """ Computes polynomial GCD using subresultants over a field. Returns ``(h, cff, cfg)`` such that ``a = gcd(f, g)``, ``cff = quo(f, h)``, and ``cfg = quo(g, h)``. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x,y, = ring("x,y", QQ) >>> f = QQ(1,2)*x**2 + x*y + QQ(1,2)*y**2 >>> g = x**2 + x*y >>> R.dmp_ff_prs_gcd(f, g) (x + y, 1/2*x + 1/2*y, x) """ if not u: return dup_ff_prs_gcd(f, g, K) result = _dmp_ff_trivial_gcd(f, g, u, K) if result is not None: return result fc, F = dmp_primitive(f, u, K) gc, G = dmp_primitive(g, u, K) h = dmp_subresultants(F, G, u, K)[-1] c, _, _ = dmp_ff_prs_gcd(fc, gc, u - 1, K) _, h = dmp_primitive(h, u, K) h = dmp_mul_term(h, c, 0, u, K) h = dmp_ground_monic(h, u, K) cff = dmp_quo(f, h, u, K) cfg = dmp_quo(g, h, u, K) return h, cff, cfg HEU_GCD_MAX = 6 def _dup_zz_gcd_interpolate(h, x, K): """Interpolate polynomial GCD from integer GCD. """ f = [] while h: g = h % x if g > x // 2: g -= x f.insert(0, g) h = (h - g) // x return f def dup_zz_heu_gcd(f, g, K): """ Heuristic polynomial GCD in `Z[x]`. Given univariate polynomials `f` and `g` in `Z[x]`, returns their GCD and cofactors, i.e. polynomials ``h``, ``cff`` and ``cfg`` such that:: h = gcd(f, g), cff = quo(f, h) and cfg = quo(g, h) The algorithm is purely heuristic which means it may fail to compute the GCD. This will be signaled by raising an exception. In this case you will need to switch to another GCD method. The algorithm computes the polynomial GCD by evaluating polynomials f and g at certain points and computing (fast) integer GCD of those evaluations. The polynomial GCD is recovered from the integer image by interpolation. The final step is to verify if the result is the correct GCD. This gives cofactors as a side effect. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_zz_heu_gcd(x**2 - 1, x**2 - 3*x + 2) (x - 1, x + 1, x - 2) References ========== .. [1] [Liao95]_ """ result = _dup_rr_trivial_gcd(f, g, K) if result is not None: return result df = dup_degree(f) dg = dup_degree(g) gcd, f, g = dup_extract(f, g, K) if df == 0 or dg == 0: return [gcd], f, g f_norm = dup_max_norm(f, K) g_norm = dup_max_norm(g, K) B = K(2*min(f_norm, g_norm) + 29) x = max(min(B, 99*K.sqrt(B)), 2*min(f_norm // abs(dup_LC(f, K)), g_norm // abs(dup_LC(g, K))) + 2) for i in range(0, HEU_GCD_MAX): ff = dup_eval(f, x, K) gg = dup_eval(g, x, K) if ff and gg: h = K.gcd(ff, gg) cff = ff // h cfg = gg // h h = _dup_zz_gcd_interpolate(h, x, K) h = dup_primitive(h, K)[1] cff_, r = dup_div(f, h, K) if not r: cfg_, r = dup_div(g, h, K) if not r: h = dup_mul_ground(h, gcd, K) return h, cff_, cfg_ cff = _dup_zz_gcd_interpolate(cff, x, K) h, r = dup_div(f, cff, K) if not r: cfg_, r = dup_div(g, h, K) if not r: h = dup_mul_ground(h, gcd, K) return h, cff, cfg_ cfg = _dup_zz_gcd_interpolate(cfg, x, K) h, r = dup_div(g, cfg, K) if not r: cff_, r = dup_div(f, h, K) if not r: h = dup_mul_ground(h, gcd, K) return h, cff_, cfg x = 73794*x * K.sqrt(K.sqrt(x)) // 27011 raise HeuristicGCDFailed('no luck') def _dmp_zz_gcd_interpolate(h, x, v, K): """Interpolate polynomial GCD from integer GCD. """ f = [] while not dmp_zero_p(h, v): g = dmp_ground_trunc(h, x, v, K) f.insert(0, g) h = dmp_sub(h, g, v, K) h = dmp_quo_ground(h, x, v, K) if K.is_negative(dmp_ground_LC(f, v + 1, K)): return dmp_neg(f, v + 1, K) else: return f def dmp_zz_heu_gcd(f, g, u, K): """ Heuristic polynomial GCD in `Z[X]`. Given univariate polynomials `f` and `g` in `Z[X]`, returns their GCD and cofactors, i.e. polynomials ``h``, ``cff`` and ``cfg`` such that:: h = gcd(f, g), cff = quo(f, h) and cfg = quo(g, h) The algorithm is purely heuristic which means it may fail to compute the GCD. This will be signaled by raising an exception. In this case you will need to switch to another GCD method. The algorithm computes the polynomial GCD by evaluating polynomials f and g at certain points and computing (fast) integer GCD of those evaluations. The polynomial GCD is recovered from the integer image by interpolation. The evaluation process reduces f and g variable by variable into a large integer. The final step is to verify if the interpolated polynomial is the correct GCD. This gives cofactors of the input polynomials as a side effect. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y, = ring("x,y", ZZ) >>> f = x**2 + 2*x*y + y**2 >>> g = x**2 + x*y >>> R.dmp_zz_heu_gcd(f, g) (x + y, x + y, x) References ========== .. [1] [Liao95]_ """ if not u: return dup_zz_heu_gcd(f, g, K) result = _dmp_rr_trivial_gcd(f, g, u, K) if result is not None: return result gcd, f, g = dmp_ground_extract(f, g, u, K) f_norm = dmp_max_norm(f, u, K) g_norm = dmp_max_norm(g, u, K) B = K(2*min(f_norm, g_norm) + 29) x = max(min(B, 99*K.sqrt(B)), 2*min(f_norm // abs(dmp_ground_LC(f, u, K)), g_norm // abs(dmp_ground_LC(g, u, K))) + 2) for i in range(0, HEU_GCD_MAX): ff = dmp_eval(f, x, u, K) gg = dmp_eval(g, x, u, K) v = u - 1 if not (dmp_zero_p(ff, v) or dmp_zero_p(gg, v)): h, cff, cfg = dmp_zz_heu_gcd(ff, gg, v, K) h = _dmp_zz_gcd_interpolate(h, x, v, K) h = dmp_ground_primitive(h, u, K)[1] cff_, r = dmp_div(f, h, u, K) if dmp_zero_p(r, u): cfg_, r = dmp_div(g, h, u, K) if dmp_zero_p(r, u): h = dmp_mul_ground(h, gcd, u, K) return h, cff_, cfg_ cff = _dmp_zz_gcd_interpolate(cff, x, v, K) h, r = dmp_div(f, cff, u, K) if dmp_zero_p(r, u): cfg_, r = dmp_div(g, h, u, K) if dmp_zero_p(r, u): h = dmp_mul_ground(h, gcd, u, K) return h, cff, cfg_ cfg = _dmp_zz_gcd_interpolate(cfg, x, v, K) h, r = dmp_div(g, cfg, u, K) if dmp_zero_p(r, u): cff_, r = dmp_div(f, h, u, K) if dmp_zero_p(r, u): h = dmp_mul_ground(h, gcd, u, K) return h, cff_, cfg x = 73794*x * K.sqrt(K.sqrt(x)) // 27011 raise HeuristicGCDFailed('no luck') def dup_qq_heu_gcd(f, g, K0): """ Heuristic polynomial GCD in `Q[x]`. Returns ``(h, cff, cfg)`` such that ``a = gcd(f, g)``, ``cff = quo(f, h)``, and ``cfg = quo(g, h)``. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x = ring("x", QQ) >>> f = QQ(1,2)*x**2 + QQ(7,4)*x + QQ(3,2) >>> g = QQ(1,2)*x**2 + x >>> R.dup_qq_heu_gcd(f, g) (x + 2, 1/2*x + 3/4, 1/2*x) """ result = _dup_ff_trivial_gcd(f, g, K0) if result is not None: return result K1 = K0.get_ring() cf, f = dup_clear_denoms(f, K0, K1) cg, g = dup_clear_denoms(g, K0, K1) f = dup_convert(f, K0, K1) g = dup_convert(g, K0, K1) h, cff, cfg = dup_zz_heu_gcd(f, g, K1) h = dup_convert(h, K1, K0) c = dup_LC(h, K0) h = dup_monic(h, K0) cff = dup_convert(cff, K1, K0) cfg = dup_convert(cfg, K1, K0) cff = dup_mul_ground(cff, K0.quo(c, cf), K0) cfg = dup_mul_ground(cfg, K0.quo(c, cg), K0) return h, cff, cfg def dmp_qq_heu_gcd(f, g, u, K0): """ Heuristic polynomial GCD in `Q[X]`. Returns ``(h, cff, cfg)`` such that ``a = gcd(f, g)``, ``cff = quo(f, h)``, and ``cfg = quo(g, h)``. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x,y, = ring("x,y", QQ) >>> f = QQ(1,4)*x**2 + x*y + y**2 >>> g = QQ(1,2)*x**2 + x*y >>> R.dmp_qq_heu_gcd(f, g) (x + 2*y, 1/4*x + 1/2*y, 1/2*x) """ result = _dmp_ff_trivial_gcd(f, g, u, K0) if result is not None: return result K1 = K0.get_ring() cf, f = dmp_clear_denoms(f, u, K0, K1) cg, g = dmp_clear_denoms(g, u, K0, K1) f = dmp_convert(f, u, K0, K1) g = dmp_convert(g, u, K0, K1) h, cff, cfg = dmp_zz_heu_gcd(f, g, u, K1) h = dmp_convert(h, u, K1, K0) c = dmp_ground_LC(h, u, K0) h = dmp_ground_monic(h, u, K0) cff = dmp_convert(cff, u, K1, K0) cfg = dmp_convert(cfg, u, K1, K0) cff = dmp_mul_ground(cff, K0.quo(c, cf), u, K0) cfg = dmp_mul_ground(cfg, K0.quo(c, cg), u, K0) return h, cff, cfg def dup_inner_gcd(f, g, K): """ Computes polynomial GCD and cofactors of `f` and `g` in `K[x]`. Returns ``(h, cff, cfg)`` such that ``a = gcd(f, g)``, ``cff = quo(f, h)``, and ``cfg = quo(g, h)``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_inner_gcd(x**2 - 1, x**2 - 3*x + 2) (x - 1, x + 1, x - 2) """ if not K.is_Exact: try: exact = K.get_exact() except DomainError: return [K.one], f, g f = dup_convert(f, K, exact) g = dup_convert(g, K, exact) h, cff, cfg = dup_inner_gcd(f, g, exact) h = dup_convert(h, exact, K) cff = dup_convert(cff, exact, K) cfg = dup_convert(cfg, exact, K) return h, cff, cfg elif K.is_Field: if K.is_QQ and query('USE_HEU_GCD'): try: return dup_qq_heu_gcd(f, g, K) except HeuristicGCDFailed: pass return dup_ff_prs_gcd(f, g, K) else: if K.is_ZZ and query('USE_HEU_GCD'): try: return dup_zz_heu_gcd(f, g, K) except HeuristicGCDFailed: pass return dup_rr_prs_gcd(f, g, K) def _dmp_inner_gcd(f, g, u, K): """Helper function for `dmp_inner_gcd()`. """ if not K.is_Exact: try: exact = K.get_exact() except DomainError: return dmp_one(u, K), f, g f = dmp_convert(f, u, K, exact) g = dmp_convert(g, u, K, exact) h, cff, cfg = _dmp_inner_gcd(f, g, u, exact) h = dmp_convert(h, u, exact, K) cff = dmp_convert(cff, u, exact, K) cfg = dmp_convert(cfg, u, exact, K) return h, cff, cfg elif K.is_Field: if K.is_QQ and query('USE_HEU_GCD'): try: return dmp_qq_heu_gcd(f, g, u, K) except HeuristicGCDFailed: pass return dmp_ff_prs_gcd(f, g, u, K) else: if K.is_ZZ and query('USE_HEU_GCD'): try: return dmp_zz_heu_gcd(f, g, u, K) except HeuristicGCDFailed: pass return dmp_rr_prs_gcd(f, g, u, K) def dmp_inner_gcd(f, g, u, K): """ Computes polynomial GCD and cofactors of `f` and `g` in `K[X]`. Returns ``(h, cff, cfg)`` such that ``a = gcd(f, g)``, ``cff = quo(f, h)``, and ``cfg = quo(g, h)``. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y, = ring("x,y", ZZ) >>> f = x**2 + 2*x*y + y**2 >>> g = x**2 + x*y >>> R.dmp_inner_gcd(f, g) (x + y, x + y, x) """ if not u: return dup_inner_gcd(f, g, K) J, (f, g) = dmp_multi_deflate((f, g), u, K) h, cff, cfg = _dmp_inner_gcd(f, g, u, K) return (dmp_inflate(h, J, u, K), dmp_inflate(cff, J, u, K), dmp_inflate(cfg, J, u, K)) def dup_gcd(f, g, K): """ Computes polynomial GCD of `f` and `g` in `K[x]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_gcd(x**2 - 1, x**2 - 3*x + 2) x - 1 """ return dup_inner_gcd(f, g, K)[0] def dmp_gcd(f, g, u, K): """ Computes polynomial GCD of `f` and `g` in `K[X]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y, = ring("x,y", ZZ) >>> f = x**2 + 2*x*y + y**2 >>> g = x**2 + x*y >>> R.dmp_gcd(f, g) x + y """ return dmp_inner_gcd(f, g, u, K)[0] def dup_rr_lcm(f, g, K): """ Computes polynomial LCM over a ring in `K[x]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_rr_lcm(x**2 - 1, x**2 - 3*x + 2) x**3 - 2*x**2 - x + 2 """ fc, f = dup_primitive(f, K) gc, g = dup_primitive(g, K) c = K.lcm(fc, gc) h = dup_quo(dup_mul(f, g, K), dup_gcd(f, g, K), K) return dup_mul_ground(h, c, K) def dup_ff_lcm(f, g, K): """ Computes polynomial LCM over a field in `K[x]`. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x = ring("x", QQ) >>> f = QQ(1,2)*x**2 + QQ(7,4)*x + QQ(3,2) >>> g = QQ(1,2)*x**2 + x >>> R.dup_ff_lcm(f, g) x**3 + 7/2*x**2 + 3*x """ h = dup_quo(dup_mul(f, g, K), dup_gcd(f, g, K), K) return dup_monic(h, K) def dup_lcm(f, g, K): """ Computes polynomial LCM of `f` and `g` in `K[x]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_lcm(x**2 - 1, x**2 - 3*x + 2) x**3 - 2*x**2 - x + 2 """ if K.is_Field: return dup_ff_lcm(f, g, K) else: return dup_rr_lcm(f, g, K) def dmp_rr_lcm(f, g, u, K): """ Computes polynomial LCM over a ring in `K[X]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y, = ring("x,y", ZZ) >>> f = x**2 + 2*x*y + y**2 >>> g = x**2 + x*y >>> R.dmp_rr_lcm(f, g) x**3 + 2*x**2*y + x*y**2 """ fc, f = dmp_ground_primitive(f, u, K) gc, g = dmp_ground_primitive(g, u, K) c = K.lcm(fc, gc) h = dmp_quo(dmp_mul(f, g, u, K), dmp_gcd(f, g, u, K), u, K) return dmp_mul_ground(h, c, u, K) def dmp_ff_lcm(f, g, u, K): """ Computes polynomial LCM over a field in `K[X]`. Examples ======== >>> from sympy.polys import ring, QQ >>> R, x,y, = ring("x,y", QQ) >>> f = QQ(1,4)*x**2 + x*y + y**2 >>> g = QQ(1,2)*x**2 + x*y >>> R.dmp_ff_lcm(f, g) x**3 + 4*x**2*y + 4*x*y**2 """ h = dmp_quo(dmp_mul(f, g, u, K), dmp_gcd(f, g, u, K), u, K) return dmp_ground_monic(h, u, K) def dmp_lcm(f, g, u, K): """ Computes polynomial LCM of `f` and `g` in `K[X]`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y, = ring("x,y", ZZ) >>> f = x**2 + 2*x*y + y**2 >>> g = x**2 + x*y >>> R.dmp_lcm(f, g) x**3 + 2*x**2*y + x*y**2 """ if not u: return dup_lcm(f, g, K) if K.is_Field: return dmp_ff_lcm(f, g, u, K) else: return dmp_rr_lcm(f, g, u, K) def dmp_content(f, u, K): """ Returns GCD of multivariate coefficients. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y, = ring("x,y", ZZ) >>> R.dmp_content(2*x*y + 6*x + 4*y + 12) 2*y + 6 """ cont, v = dmp_LC(f, K), u - 1 if dmp_zero_p(f, u): return cont for c in f[1:]: cont = dmp_gcd(cont, c, v, K) if dmp_one_p(cont, v, K): break if K.is_negative(dmp_ground_LC(cont, v, K)): return dmp_neg(cont, v, K) else: return cont def dmp_primitive(f, u, K): """ Returns multivariate content and a primitive polynomial. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y, = ring("x,y", ZZ) >>> R.dmp_primitive(2*x*y + 6*x + 4*y + 12) (2*y + 6, x + 2) """ cont, v = dmp_content(f, u, K), u - 1 if dmp_zero_p(f, u) or dmp_one_p(cont, v, K): return cont, f else: return cont, [ dmp_quo(c, cont, v, K) for c in f ] def dup_cancel(f, g, K, include=True): """ Cancel common factors in a rational function `f/g`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_cancel(2*x**2 - 2, x**2 - 2*x + 1) (2*x + 2, x - 1) """ return dmp_cancel(f, g, 0, K, include=include) def dmp_cancel(f, g, u, K, include=True): """ Cancel common factors in a rational function `f/g`. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_cancel(2*x**2 - 2, x**2 - 2*x + 1) (2*x + 2, x - 1) """ K0 = None if K.is_Field and K.has_assoc_Ring: K0, K = K, K.get_ring() cq, f = dmp_clear_denoms(f, u, K0, K, convert=True) cp, g = dmp_clear_denoms(g, u, K0, K, convert=True) else: cp, cq = K.one, K.one _, p, q = dmp_inner_gcd(f, g, u, K) if K0 is not None: _, cp, cq = K.cofactors(cp, cq) p = dmp_convert(p, u, K, K0) q = dmp_convert(q, u, K, K0) K = K0 p_neg = K.is_negative(dmp_ground_LC(p, u, K)) q_neg = K.is_negative(dmp_ground_LC(q, u, K)) if p_neg and q_neg: p, q = dmp_neg(p, u, K), dmp_neg(q, u, K) elif p_neg: cp, p = -cp, dmp_neg(p, u, K) elif q_neg: cp, q = -cp, dmp_neg(q, u, K) if not include: return cp, cq, p, q p = dmp_mul_ground(p, cp, u, K) q = dmp_mul_ground(q, cq, u, K) return p, q

b858624d0c0075f11c4b91f0fc82ac946cb8773cf3553b007dcdd698ea1317cb

"""Tools for constructing domains for expressions. """ from __future__ import print_function, division from sympy.core import sympify from sympy.polys.domains import ZZ, QQ, EX from sympy.polys.domains.realfield import RealField from sympy.polys.polyoptions import build_options from sympy.polys.polyutils import parallel_dict_from_basic from sympy.utilities import public def _construct_simple(coeffs, opt): """Handle simple domains, e.g.: ZZ, QQ, RR and algebraic domains. """ result, rationals, reals, algebraics = {}, False, False, False if opt.extension is True: is_algebraic = lambda coeff: coeff.is_number and coeff.is_algebraic else: is_algebraic = lambda coeff: False # XXX: add support for a + b*I coefficients for coeff in coeffs: if coeff.is_Rational: if not coeff.is_Integer: rationals = True elif coeff.is_Float: if not algebraics: reals = True else: # there are both reals and algebraics -> EX return False elif is_algebraic(coeff): if not reals: algebraics = True else: # there are both algebraics and reals -> EX return False else: # this is a composite domain, e.g. ZZ[X], EX return None if algebraics: domain, result = _construct_algebraic(coeffs, opt) else: if reals: # Use the maximum precision of all coefficients for the RR's # precision max_prec = max([c._prec for c in coeffs]) domain = RealField(prec=max_prec) else: if opt.field or rationals: domain = QQ else: domain = ZZ result = [] for coeff in coeffs: result.append(domain.from_sympy(coeff)) return domain, result def _construct_algebraic(coeffs, opt): """We know that coefficients are algebraic so construct the extension. """ from sympy.polys.numberfields import primitive_element result, exts = [], set([]) for coeff in coeffs: if coeff.is_Rational: coeff = (None, 0, QQ.from_sympy(coeff)) else: a = coeff.as_coeff_add()[0] coeff -= a b = coeff.as_coeff_mul()[0] coeff /= b exts.add(coeff) a = QQ.from_sympy(a) b = QQ.from_sympy(b) coeff = (coeff, b, a) result.append(coeff) exts = list(exts) g, span, H = primitive_element(exts, ex=True, polys=True) root = sum([ s*ext for s, ext in zip(span, exts) ]) domain, g = QQ.algebraic_field((g, root)), g.rep.rep for i, (coeff, a, b) in enumerate(result): if coeff is not None: coeff = a*domain.dtype.from_list(H[exts.index(coeff)], g, QQ) + b else: coeff = domain.dtype.from_list([b], g, QQ) result[i] = coeff return domain, result def _construct_composite(coeffs, opt): """Handle composite domains, e.g.: ZZ[X], QQ[X], ZZ(X), QQ(X). """ numers, denoms = [], [] for coeff in coeffs: numer, denom = coeff.as_numer_denom() numers.append(numer) denoms.append(denom) polys, gens = parallel_dict_from_basic(numers + denoms) # XXX: sorting if not gens: return None if opt.composite is None: if any(gen.is_number and gen.is_algebraic for gen in gens): return None # generators are number-like so lets better use EX all_symbols = set([]) for gen in gens: symbols = gen.free_symbols if all_symbols & symbols: return None # there could be algebraic relations between generators else: all_symbols |= symbols n = len(gens) k = len(polys)//2 numers = polys[:k] denoms = polys[k:] if opt.field: fractions = True else: fractions, zeros = False, (0,)*n for denom in denoms: if len(denom) > 1 or zeros not in denom: fractions = True break coeffs = set([]) if not fractions: for numer, denom in zip(numers, denoms): denom = denom[zeros] for monom, coeff in numer.items(): coeff /= denom coeffs.add(coeff) numer[monom] = coeff else: for numer, denom in zip(numers, denoms): coeffs.update(list(numer.values())) coeffs.update(list(denom.values())) rationals, reals = False, False for coeff in coeffs: if coeff.is_Rational: if not coeff.is_Integer: rationals = True elif coeff.is_Float: reals = True break if reals: max_prec = max([c._prec for c in coeffs]) ground = RealField(prec=max_prec) elif rationals: ground = QQ else: ground = ZZ result = [] if not fractions: domain = ground.poly_ring(*gens) for numer in numers: for monom, coeff in numer.items(): numer[monom] = ground.from_sympy(coeff) result.append(domain(numer)) else: domain = ground.frac_field(*gens) for numer, denom in zip(numers, denoms): for monom, coeff in numer.items(): numer[monom] = ground.from_sympy(coeff) for monom, coeff in denom.items(): denom[monom] = ground.from_sympy(coeff) result.append(domain((numer, denom))) return domain, result def _construct_expression(coeffs, opt): """The last resort case, i.e. use the expression domain. """ domain, result = EX, [] for coeff in coeffs: result.append(domain.from_sympy(coeff)) return domain, result @public def construct_domain(obj, **args): """Construct a minimal domain for the list of coefficients. """ opt = build_options(args) if hasattr(obj, '__iter__'): if isinstance(obj, dict): if not obj: monoms, coeffs = [], [] else: monoms, coeffs = list(zip(*list(obj.items()))) else: coeffs = obj else: coeffs = [obj] coeffs = list(map(sympify, coeffs)) result = _construct_simple(coeffs, opt) if result is not None: if result is not False: domain, coeffs = result else: domain, coeffs = _construct_expression(coeffs, opt) else: if opt.composite is False: result = None else: result = _construct_composite(coeffs, opt) if result is not None: domain, coeffs = result else: domain, coeffs = _construct_expression(coeffs, opt) if hasattr(obj, '__iter__'): if isinstance(obj, dict): return domain, dict(list(zip(monoms, coeffs))) else: return domain, coeffs else: return domain, coeffs[0]

0cf6e79c153059c91ad77dff8e2fc98ee8b01cb8594d0e9efe20326092fa6793

"""Polynomial factorization routines in characteristic zero. """ from __future__ import print_function, division from sympy.polys.galoistools import ( gf_from_int_poly, gf_to_int_poly, gf_lshift, gf_add_mul, gf_mul, gf_div, gf_rem, gf_gcdex, gf_sqf_p, gf_factor_sqf, gf_factor) from sympy.polys.densebasic import ( dup_LC, dmp_LC, dmp_ground_LC, dup_TC, dup_convert, dmp_convert, dup_degree, dmp_degree, dmp_degree_in, dmp_degree_list, dmp_from_dict, dmp_zero_p, dmp_one, dmp_nest, dmp_raise, dup_strip, dmp_ground, dup_inflate, dmp_exclude, dmp_include, dmp_inject, dmp_eject, dup_terms_gcd, dmp_terms_gcd) from sympy.polys.densearith import ( dup_neg, dmp_neg, dup_add, dmp_add, dup_sub, dmp_sub, dup_mul, dmp_mul, dup_sqr, dmp_pow, dup_div, dmp_div, dup_quo, dmp_quo, dmp_expand, dmp_add_mul, dup_sub_mul, dmp_sub_mul, dup_lshift, dup_max_norm, dmp_max_norm, dup_l1_norm, dup_mul_ground, dmp_mul_ground, dup_quo_ground, dmp_quo_ground) from sympy.polys.densetools import ( dup_clear_denoms, dmp_clear_denoms, dup_trunc, dmp_ground_trunc, dup_content, dup_monic, dmp_ground_monic, dup_primitive, dmp_ground_primitive, dmp_eval_tail, dmp_eval_in, dmp_diff_eval_in, dmp_compose, dup_shift, dup_mirror) from sympy.polys.euclidtools import ( dmp_primitive, dup_inner_gcd, dmp_inner_gcd) from sympy.polys.sqfreetools import ( dup_sqf_p, dup_sqf_norm, dmp_sqf_norm, dup_sqf_part, dmp_sqf_part) from sympy.polys.polyutils import _sort_factors from sympy.polys.polyconfig import query from sympy.polys.polyerrors import ( ExtraneousFactors, DomainError, CoercionFailed, EvaluationFailed) from sympy.ntheory import nextprime, isprime, factorint from sympy.utilities import subsets from math import ceil as _ceil, log as _log from sympy.core.compatibility import range def dup_trial_division(f, factors, K): """Determine multiplicities of factors using trial division. """ result = [] for factor in factors: k = 0 while True: q, r = dup_div(f, factor, K) if not r: f, k = q, k + 1 else: break result.append((factor, k)) return _sort_factors(result) def dmp_trial_division(f, factors, u, K): """Determine multiplicities of factors using trial division. """ result = [] for factor in factors: k = 0 while True: q, r = dmp_div(f, factor, u, K) if dmp_zero_p(r, u): f, k = q, k + 1 else: break result.append((factor, k)) return _sort_factors(result) def dup_zz_mignotte_bound(f, K): """Mignotte bound for univariate polynomials in `K[x]`. """ a = dup_max_norm(f, K) b = abs(dup_LC(f, K)) n = dup_degree(f) return K.sqrt(K(n + 1))*2**n*a*b def dmp_zz_mignotte_bound(f, u, K): """Mignotte bound for multivariate polynomials in `K[X]`. """ a = dmp_max_norm(f, u, K) b = abs(dmp_ground_LC(f, u, K)) n = sum(dmp_degree_list(f, u)) return K.sqrt(K(n + 1))*2**n*a*b def dup_zz_hensel_step(m, f, g, h, s, t, K): """ One step in Hensel lifting in `Z[x]`. Given positive integer `m` and `Z[x]` polynomials `f`, `g`, `h`, `s` and `t` such that:: f == g*h (mod m) s*g + t*h == 1 (mod m) lc(f) is not a zero divisor (mod m) lc(h) == 1 deg(f) == deg(g) + deg(h) deg(s) < deg(h) deg(t) < deg(g) returns polynomials `G`, `H`, `S` and `T`, such that:: f == G*H (mod m**2) S*G + T**H == 1 (mod m**2) References ========== .. [1] [Gathen99]_ """ M = m**2 e = dup_sub_mul(f, g, h, K) e = dup_trunc(e, M, K) q, r = dup_div(dup_mul(s, e, K), h, K) q = dup_trunc(q, M, K) r = dup_trunc(r, M, K) u = dup_add(dup_mul(t, e, K), dup_mul(q, g, K), K) G = dup_trunc(dup_add(g, u, K), M, K) H = dup_trunc(dup_add(h, r, K), M, K) u = dup_add(dup_mul(s, G, K), dup_mul(t, H, K), K) b = dup_trunc(dup_sub(u, [K.one], K), M, K) c, d = dup_div(dup_mul(s, b, K), H, K) c = dup_trunc(c, M, K) d = dup_trunc(d, M, K) u = dup_add(dup_mul(t, b, K), dup_mul(c, G, K), K) S = dup_trunc(dup_sub(s, d, K), M, K) T = dup_trunc(dup_sub(t, u, K), M, K) return G, H, S, T def dup_zz_hensel_lift(p, f, f_list, l, K): """ Multifactor Hensel lifting in `Z[x]`. Given a prime `p`, polynomial `f` over `Z[x]` such that `lc(f)` is a unit modulo `p`, monic pair-wise coprime polynomials `f_i` over `Z[x]` satisfying:: f = lc(f) f_1 ... f_r (mod p) and a positive integer `l`, returns a list of monic polynomials `F_1`, `F_2`, ..., `F_r` satisfying:: f = lc(f) F_1 ... F_r (mod p**l) F_i = f_i (mod p), i = 1..r References ========== .. [1] [Gathen99]_ """ r = len(f_list) lc = dup_LC(f, K) if r == 1: F = dup_mul_ground(f, K.gcdex(lc, p**l)[0], K) return [ dup_trunc(F, p**l, K) ] m = p k = r // 2 d = int(_ceil(_log(l, 2))) g = gf_from_int_poly([lc], p) for f_i in f_list[:k]: g = gf_mul(g, gf_from_int_poly(f_i, p), p, K) h = gf_from_int_poly(f_list[k], p) for f_i in f_list[k + 1:]: h = gf_mul(h, gf_from_int_poly(f_i, p), p, K) s, t, _ = gf_gcdex(g, h, p, K) g = gf_to_int_poly(g, p) h = gf_to_int_poly(h, p) s = gf_to_int_poly(s, p) t = gf_to_int_poly(t, p) for _ in range(1, d + 1): (g, h, s, t), m = dup_zz_hensel_step(m, f, g, h, s, t, K), m**2 return dup_zz_hensel_lift(p, g, f_list[:k], l, K) \ + dup_zz_hensel_lift(p, h, f_list[k:], l, K) def _test_pl(fc, q, pl): if q > pl // 2: q = q - pl if not q: return True return fc % q == 0 def dup_zz_zassenhaus(f, K): """Factor primitive square-free polynomials in `Z[x]`. """ n = dup_degree(f) if n == 1: return [f] fc = f[-1] A = dup_max_norm(f, K) b = dup_LC(f, K) B = int(abs(K.sqrt(K(n + 1))*2**n*A*b)) C = int((n + 1)**(2*n)*A**(2*n - 1)) gamma = int(_ceil(2*_log(C, 2))) bound = int(2*gamma*_log(gamma)) a = [] # choose a prime number `p` such that `f` be square free in Z_p # if there are many factors in Z_p, choose among a few different `p` # the one with fewer factors for px in range(3, bound + 1): if not isprime(px) or b % px == 0: continue px = K.convert(px) F = gf_from_int_poly(f, px) if not gf_sqf_p(F, px, K): continue fsqfx = gf_factor_sqf(F, px, K)[1] a.append((px, fsqfx)) if len(fsqfx) < 15 or len(a) > 4: break p, fsqf = min(a, key=lambda x: len(x[1])) l = int(_ceil(_log(2*B + 1, p))) modular = [gf_to_int_poly(ff, p) for ff in fsqf] g = dup_zz_hensel_lift(p, f, modular, l, K) sorted_T = range(len(g)) T = set(sorted_T) factors, s = [], 1 pl = p**l while 2*s <= len(T): for S in subsets(sorted_T, s): # lift the constant coefficient of the product `G` of the factors # in the subset `S`; if it is does not divide `fc`, `G` does # not divide the input polynomial if b == 1: q = 1 for i in S: q = q*g[i][-1] q = q % pl if not _test_pl(fc, q, pl): continue else: G = [b] for i in S: G = dup_mul(G, g[i], K) G = dup_trunc(G, pl, K) G = dup_primitive(G, K)[1] q = G[-1] if q and fc % q != 0: continue H = [b] S = set(S) T_S = T - S if b == 1: G = [b] for i in S: G = dup_mul(G, g[i], K) G = dup_trunc(G, pl, K) for i in T_S: H = dup_mul(H, g[i], K) H = dup_trunc(H, pl, K) G_norm = dup_l1_norm(G, K) H_norm = dup_l1_norm(H, K) if G_norm*H_norm <= B: T = T_S sorted_T = [i for i in sorted_T if i not in S] G = dup_primitive(G, K)[1] f = dup_primitive(H, K)[1] factors.append(G) b = dup_LC(f, K) break else: s += 1 return factors + [f] def dup_zz_irreducible_p(f, K): """Test irreducibility using Eisenstein's criterion. """ lc = dup_LC(f, K) tc = dup_TC(f, K) e_fc = dup_content(f[1:], K) if e_fc: e_ff = factorint(int(e_fc)) for p in e_ff.keys(): if (lc % p) and (tc % p**2): return True def dup_cyclotomic_p(f, K, irreducible=False): """ Efficiently test if ``f`` is a cyclotomic polnomial. Examples ======== >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> f = x**16 + x**14 - x**10 + x**8 - x**6 + x**2 + 1 >>> R.dup_cyclotomic_p(f) False >>> g = x**16 + x**14 - x**10 - x**8 - x**6 + x**2 + 1 >>> R.dup_cyclotomic_p(g) True """ if K.is_QQ: try: K0, K = K, K.get_ring() f = dup_convert(f, K0, K) except CoercionFailed: return False elif not K.is_ZZ: return False lc = dup_LC(f, K) tc = dup_TC(f, K) if lc != 1 or (tc != -1 and tc != 1): return False if not irreducible: coeff, factors = dup_factor_list(f, K) if coeff != K.one or factors != [(f, 1)]: return False n = dup_degree(f) g, h = [], [] for i in range(n, -1, -2): g.insert(0, f[i]) for i in range(n - 1, -1, -2): h.insert(0, f[i]) g = dup_sqr(dup_strip(g), K) h = dup_sqr(dup_strip(h), K) F = dup_sub(g, dup_lshift(h, 1, K), K) if K.is_negative(dup_LC(F, K)): F = dup_neg(F, K) if F == f: return True g = dup_mirror(f, K) if K.is_negative(dup_LC(g, K)): g = dup_neg(g, K) if F == g and dup_cyclotomic_p(g, K): return True G = dup_sqf_part(F, K) if dup_sqr(G, K) == F and dup_cyclotomic_p(G, K): return True return False def dup_zz_cyclotomic_poly(n, K): """Efficiently generate n-th cyclotomic polnomial. """ h = [K.one, -K.one] for p, k in factorint(n).items(): h = dup_quo(dup_inflate(h, p, K), h, K) h = dup_inflate(h, p**(k - 1), K) return h def _dup_cyclotomic_decompose(n, K): H = [[K.one, -K.one]] for p, k in factorint(n).items(): Q = [ dup_quo(dup_inflate(h, p, K), h, K) for h in H ] H.extend(Q) for i in range(1, k): Q = [ dup_inflate(q, p, K) for q in Q ] H.extend(Q) return H def dup_zz_cyclotomic_factor(f, K): """ Efficiently factor polynomials `x**n - 1` and `x**n + 1` in `Z[x]`. Given a univariate polynomial `f` in `Z[x]` returns a list of factors of `f`, provided that `f` is in the form `x**n - 1` or `x**n + 1` for `n >= 1`. Otherwise returns None. Factorization is performed using using cyclotomic decomposition of `f`, which makes this method much faster that any other direct factorization approach (e.g. Zassenhaus's). References ========== .. [1] [Weisstein09]_ """ lc_f, tc_f = dup_LC(f, K), dup_TC(f, K) if dup_degree(f) <= 0: return None if lc_f != 1 or tc_f not in [-1, 1]: return None if any(bool(cf) for cf in f[1:-1]): return None n = dup_degree(f) F = _dup_cyclotomic_decompose(n, K) if not K.is_one(tc_f): return F else: H = [] for h in _dup_cyclotomic_decompose(2*n, K): if h not in F: H.append(h) return H def dup_zz_factor_sqf(f, K): """Factor square-free (non-primitive) polyomials in `Z[x]`. """ cont, g = dup_primitive(f, K) n = dup_degree(g) if dup_LC(g, K) < 0: cont, g = -cont, dup_neg(g, K) if n <= 0: return cont, [] elif n == 1: return cont, [g] if query('USE_IRREDUCIBLE_IN_FACTOR'): if dup_zz_irreducible_p(g, K): return cont, [g] factors = None if query('USE_CYCLOTOMIC_FACTOR'): factors = dup_zz_cyclotomic_factor(g, K) if factors is None: factors = dup_zz_zassenhaus(g, K) return cont, _sort_factors(factors, multiple=False) def dup_zz_factor(f, K): """ Factor (non square-free) polynomials in `Z[x]`. Given a univariate polynomial `f` in `Z[x]` computes its complete factorization `f_1, ..., f_n` into irreducibles over integers:: f = content(f) f_1**k_1 ... f_n**k_n The factorization is computed by reducing the input polynomial into a primitive square-free polynomial and factoring it using Zassenhaus algorithm. Trial division is used to recover the multiplicities of factors. The result is returned as a tuple consisting of:: (content(f), [(f_1, k_1), ..., (f_n, k_n)) Examples ======== Consider the polynomial `f = 2*x**4 - 2`:: >>> from sympy.polys import ring, ZZ >>> R, x = ring("x", ZZ) >>> R.dup_zz_factor(2*x**4 - 2) (2, [(x - 1, 1), (x + 1, 1), (x**2 + 1, 1)]) In result we got the following factorization:: f = 2 (x - 1) (x + 1) (x**2 + 1) Note that this is a complete factorization over integers, however over Gaussian integers we can factor the last term. By default, polynomials `x**n - 1` and `x**n + 1` are factored using cyclotomic decomposition to speedup computations. To disable this behaviour set cyclotomic=False. References ========== .. [1] [Gathen99]_ """ cont, g = dup_primitive(f, K) n = dup_degree(g) if dup_LC(g, K) < 0: cont, g = -cont, dup_neg(g, K) if n <= 0: return cont, [] elif n == 1: return cont, [(g, 1)] if query('USE_IRREDUCIBLE_IN_FACTOR'): if dup_zz_irreducible_p(g, K): return cont, [(g, 1)] g = dup_sqf_part(g, K) H = None if query('USE_CYCLOTOMIC_FACTOR'): H = dup_zz_cyclotomic_factor(g, K) if H is None: H = dup_zz_zassenhaus(g, K) factors = dup_trial_division(f, H, K) return cont, factors def dmp_zz_wang_non_divisors(E, cs, ct, K): """Wang/EEZ: Compute a set of valid divisors. """ result = [ cs*ct ] for q in E: q = abs(q) for r in reversed(result): while r != 1: r = K.gcd(r, q) q = q // r if K.is_one(q): return None result.append(q) return result[1:] def dmp_zz_wang_test_points(f, T, ct, A, u, K): """Wang/EEZ: Test evaluation points for suitability. """ if not dmp_eval_tail(dmp_LC(f, K), A, u - 1, K): raise EvaluationFailed('no luck') g = dmp_eval_tail(f, A, u, K) if not dup_sqf_p(g, K): raise EvaluationFailed('no luck') c, h = dup_primitive(g, K) if K.is_negative(dup_LC(h, K)): c, h = -c, dup_neg(h, K) v = u - 1 E = [ dmp_eval_tail(t, A, v, K) for t, _ in T ] D = dmp_zz_wang_non_divisors(E, c, ct, K) if D is not None: return c, h, E else: raise EvaluationFailed('no luck') def dmp_zz_wang_lead_coeffs(f, T, cs, E, H, A, u, K): """Wang/EEZ: Compute correct leading coefficients. """ C, J, v = [], [0]*len(E), u - 1 for h in H: c = dmp_one(v, K) d = dup_LC(h, K)*cs for i in reversed(range(len(E))): k, e, (t, _) = 0, E[i], T[i] while not (d % e): d, k = d//e, k + 1 if k != 0: c, J[i] = dmp_mul(c, dmp_pow(t, k, v, K), v, K), 1 C.append(c) if any(not j for j in J): raise ExtraneousFactors # pragma: no cover CC, HH = [], [] for c, h in zip(C, H): d = dmp_eval_tail(c, A, v, K) lc = dup_LC(h, K) if K.is_one(cs): cc = lc//d else: g = K.gcd(lc, d) d, cc = d//g, lc//g h, cs = dup_mul_ground(h, d, K), cs//d c = dmp_mul_ground(c, cc, v, K) CC.append(c) HH.append(h) if K.is_one(cs): return f, HH, CC CCC, HHH = [], [] for c, h in zip(CC, HH): CCC.append(dmp_mul_ground(c, cs, v, K)) HHH.append(dmp_mul_ground(h, cs, 0, K)) f = dmp_mul_ground(f, cs**(len(H) - 1), u, K) return f, HHH, CCC def dup_zz_diophantine(F, m, p, K): """Wang/EEZ: Solve univariate Diophantine equations. """ if len(F) == 2: a, b = F f = gf_from_int_poly(a, p) g = gf_from_int_poly(b, p) s, t, G = gf_gcdex(g, f, p, K) s = gf_lshift(s, m, K) t = gf_lshift(t, m, K) q, s = gf_div(s, f, p, K) t = gf_add_mul(t, q, g, p, K) s = gf_to_int_poly(s, p) t = gf_to_int_poly(t, p) result = [s, t] else: G = [F[-1]] for f in reversed(F[1:-1]): G.insert(0, dup_mul(f, G[0], K)) S, T = [], [[1]] for f, g in zip(F, G): t, s = dmp_zz_diophantine([g, f], T[-1], [], 0, p, 1, K) T.append(t) S.append(s) result, S = [], S + [T[-1]] for s, f in zip(S, F): s = gf_from_int_poly(s, p) f = gf_from_int_poly(f, p) r = gf_rem(gf_lshift(s, m, K), f, p, K) s = gf_to_int_poly(r, p) result.append(s) return result def dmp_zz_diophantine(F, c, A, d, p, u, K): """Wang/EEZ: Solve multivariate Diophantine equations. """ if not A: S = [ [] for _ in F ] n = dup_degree(c) for i, coeff in enumerate(c): if not coeff: continue T = dup_zz_diophantine(F, n - i, p, K) for j, (s, t) in enumerate(zip(S, T)): t = dup_mul_ground(t, coeff, K) S[j] = dup_trunc(dup_add(s, t, K), p, K) else: n = len(A) e = dmp_expand(F, u, K) a, A = A[-1], A[:-1] B, G = [], [] for f in F: B.append(dmp_quo(e, f, u, K)) G.append(dmp_eval_in(f, a, n, u, K)) C = dmp_eval_in(c, a, n, u, K) v = u - 1 S = dmp_zz_diophantine(G, C, A, d, p, v, K) S = [ dmp_raise(s, 1, v, K) for s in S ] for s, b in zip(S, B): c = dmp_sub_mul(c, s, b, u, K) c = dmp_ground_trunc(c, p, u, K) m = dmp_nest([K.one, -a], n, K) M = dmp_one(n, K) for k in K.map(range(0, d)): if dmp_zero_p(c, u): break M = dmp_mul(M, m, u, K) C = dmp_diff_eval_in(c, k + 1, a, n, u, K) if not dmp_zero_p(C, v): C = dmp_quo_ground(C, K.factorial(k + 1), v, K) T = dmp_zz_diophantine(G, C, A, d, p, v, K) for i, t in enumerate(T): T[i] = dmp_mul(dmp_raise(t, 1, v, K), M, u, K) for i, (s, t) in enumerate(zip(S, T)): S[i] = dmp_add(s, t, u, K) for t, b in zip(T, B): c = dmp_sub_mul(c, t, b, u, K) c = dmp_ground_trunc(c, p, u, K) S = [ dmp_ground_trunc(s, p, u, K) for s in S ] return S def dmp_zz_wang_hensel_lifting(f, H, LC, A, p, u, K): """Wang/EEZ: Parallel Hensel lifting algorithm. """ S, n, v = [f], len(A), u - 1 H = list(H) for i, a in enumerate(reversed(A[1:])): s = dmp_eval_in(S[0], a, n - i, u - i, K) S.insert(0, dmp_ground_trunc(s, p, v - i, K)) d = max(dmp_degree_list(f, u)[1:]) for j, s, a in zip(range(2, n + 2), S, A): G, w = list(H), j - 1 I, J = A[:j - 2], A[j - 1:] for i, (h, lc) in enumerate(zip(H, LC)): lc = dmp_ground_trunc(dmp_eval_tail(lc, J, v, K), p, w - 1, K) H[i] = [lc] + dmp_raise(h[1:], 1, w - 1, K) m = dmp_nest([K.one, -a], w, K) M = dmp_one(w, K) c = dmp_sub(s, dmp_expand(H, w, K), w, K) dj = dmp_degree_in(s, w, w) for k in K.map(range(0, dj)): if dmp_zero_p(c, w): break M = dmp_mul(M, m, w, K) C = dmp_diff_eval_in(c, k + 1, a, w, w, K) if not dmp_zero_p(C, w - 1): C = dmp_quo_ground(C, K.factorial(k + 1), w - 1, K) T = dmp_zz_diophantine(G, C, I, d, p, w - 1, K) for i, (h, t) in enumerate(zip(H, T)): h = dmp_add_mul(h, dmp_raise(t, 1, w - 1, K), M, w, K) H[i] = dmp_ground_trunc(h, p, w, K) h = dmp_sub(s, dmp_expand(H, w, K), w, K) c = dmp_ground_trunc(h, p, w, K) if dmp_expand(H, u, K) != f: raise ExtraneousFactors # pragma: no cover else: return H def dmp_zz_wang(f, u, K, mod=None, seed=None): """ Factor primitive square-free polynomials in `Z[X]`. Given a multivariate polynomial `f` in `Z[x_1,...,x_n]`, which is primitive and square-free in `x_1`, computes factorization of `f` into irreducibles over integers. The procedure is based on Wang's Enhanced Extended Zassenhaus algorithm. The algorithm works by viewing `f` as a univariate polynomial in `Z[x_2,...,x_n][x_1]`, for which an evaluation mapping is computed:: x_2 -> a_2, ..., x_n -> a_n where `a_i`, for `i = 2, ..., n`, are carefully chosen integers. The mapping is used to transform `f` into a univariate polynomial in `Z[x_1]`, which can be factored efficiently using Zassenhaus algorithm. The last step is to lift univariate factors to obtain true multivariate factors. For this purpose a parallel Hensel lifting procedure is used. The parameter ``seed`` is passed to _randint and can be used to seed randint (when an integer) or (for testing purposes) can be a sequence of numbers. References ========== .. [1] [Wang78]_ .. [2] [Geddes92]_ """ from sympy.utilities.randtest import _randint randint = _randint(seed) ct, T = dmp_zz_factor(dmp_LC(f, K), u - 1, K) b = dmp_zz_mignotte_bound(f, u, K) p = K(nextprime(b)) if mod is None: if u == 1: mod = 2 else: mod = 1 history, configs, A, r = set([]), [], [K.zero]*u, None try: cs, s, E = dmp_zz_wang_test_points(f, T, ct, A, u, K) _, H = dup_zz_factor_sqf(s, K) r = len(H) if r == 1: return [f] configs = [(s, cs, E, H, A)] except EvaluationFailed: pass eez_num_configs = query('EEZ_NUMBER_OF_CONFIGS') eez_num_tries = query('EEZ_NUMBER_OF_TRIES') eez_mod_step = query('EEZ_MODULUS_STEP') while len(configs) < eez_num_configs: for _ in range(eez_num_tries): A = [ K(randint(-mod, mod)) for _ in range(u) ] if tuple(A) not in history: history.add(tuple(A)) else: continue try: cs, s, E = dmp_zz_wang_test_points(f, T, ct, A, u, K) except EvaluationFailed: continue _, H = dup_zz_factor_sqf(s, K) rr = len(H) if r is not None: if rr != r: # pragma: no cover if rr < r: configs, r = [], rr else: continue else: r = rr if r == 1: return [f] configs.append((s, cs, E, H, A)) if len(configs) == eez_num_configs: break else: mod += eez_mod_step s_norm, s_arg, i = None, 0, 0 for s, _, _, _, _ in configs: _s_norm = dup_max_norm(s, K) if s_norm is not None: if _s_norm < s_norm: s_norm = _s_norm s_arg = i else: s_norm = _s_norm i += 1 _, cs, E, H, A = configs[s_arg] orig_f = f try: f, H, LC = dmp_zz_wang_lead_coeffs(f, T, cs, E, H, A, u, K) factors = dmp_zz_wang_hensel_lifting(f, H, LC, A, p, u, K) except ExtraneousFactors: # pragma: no cover if query('EEZ_RESTART_IF_NEEDED'): return dmp_zz_wang(orig_f, u, K, mod + 1) else: raise ExtraneousFactors( "we need to restart algorithm with better parameters") result = [] for f in factors: _, f = dmp_ground_primitive(f, u, K) if K.is_negative(dmp_ground_LC(f, u, K)): f = dmp_neg(f, u, K) result.append(f) return result def dmp_zz_factor(f, u, K): """ Factor (non square-free) polynomials in `Z[X]`. Given a multivariate polynomial `f` in `Z[x]` computes its complete factorization `f_1, ..., f_n` into irreducibles over integers:: f = content(f) f_1**k_1 ... f_n**k_n The factorization is computed by reducing the input polynomial into a primitive square-free polynomial and factoring it using Enhanced Extended Zassenhaus (EEZ) algorithm. Trial division is used to recover the multiplicities of factors. The result is returned as a tuple consisting of:: (content(f), [(f_1, k_1), ..., (f_n, k_n)) Consider polynomial `f = 2*(x**2 - y**2)`:: >>> from sympy.polys import ring, ZZ >>> R, x,y = ring("x,y", ZZ) >>> R.dmp_zz_factor(2*x**2 - 2*y**2) (2, [(x - y, 1), (x + y, 1)]) In result we got the following factorization:: f = 2 (x - y) (x + y) References ========== .. [1] [Gathen99]_ """ if not u: return dup_zz_factor(f, K) if dmp_zero_p(f, u): return K.zero, [] cont, g = dmp_ground_primitive(f, u, K) if dmp_ground_LC(g, u, K) < 0: cont, g = -cont, dmp_neg(g, u, K) if all(d <= 0 for d in dmp_degree_list(g, u)): return cont, [] G, g = dmp_primitive(g, u, K) factors = [] if dmp_degree(g, u) > 0: g = dmp_sqf_part(g, u, K) H = dmp_zz_wang(g, u, K) factors = dmp_trial_division(f, H, u, K) for g, k in dmp_zz_factor(G, u - 1, K)[1]: factors.insert(0, ([g], k)) return cont, _sort_factors(factors) def dup_ext_factor(f, K): """Factor univariate polynomials over algebraic number fields. """ n, lc = dup_degree(f), dup_LC(f, K) f = dup_monic(f, K) if n <= 0: return lc, [] if n == 1: return lc, [(f, 1)] f, F = dup_sqf_part(f, K), f s, g, r = dup_sqf_norm(f, K) factors = dup_factor_list_include(r, K.dom) if len(factors) == 1: return lc, [(f, n//dup_degree(f))] H = s*K.unit for i, (factor, _) in enumerate(factors): h = dup_convert(factor, K.dom, K) h, _, g = dup_inner_gcd(h, g, K) h = dup_shift(h, H, K) factors[i] = h factors = dup_trial_division(F, factors, K) return lc, factors def dmp_ext_factor(f, u, K): """Factor multivariate polynomials over algebraic number fields. """ if not u: return dup_ext_factor(f, K) lc = dmp_ground_LC(f, u, K) f = dmp_ground_monic(f, u, K) if all(d <= 0 for d in dmp_degree_list(f, u)): return lc, [] f, F = dmp_sqf_part(f, u, K), f s, g, r = dmp_sqf_norm(f, u, K) factors = dmp_factor_list_include(r, u, K.dom) if len(factors) == 1: factors = [f] else: H = dmp_raise([K.one, s*K.unit], u, 0, K) for i, (factor, _) in enumerate(factors): h = dmp_convert(factor, u, K.dom, K) h, _, g = dmp_inner_gcd(h, g, u, K) h = dmp_compose(h, H, u, K) factors[i] = h return lc, dmp_trial_division(F, factors, u, K) def dup_gf_factor(f, K): """Factor univariate polynomials over finite fields. """ f = dup_convert(f, K, K.dom) coeff, factors = gf_factor(f, K.mod, K.dom) for i, (f, k) in enumerate(factors): factors[i] = (dup_convert(f, K.dom, K), k) return K.convert(coeff, K.dom), factors def dmp_gf_factor(f, u, K): """Factor multivariate polynomials over finite fields. """ raise NotImplementedError('multivariate polynomials over finite fields') def dup_factor_list(f, K0): """Factor polynomials into irreducibles in `K[x]`. """ j, f = dup_terms_gcd(f, K0) cont, f = dup_primitive(f, K0) if K0.is_FiniteField: coeff, factors = dup_gf_factor(f, K0) elif K0.is_Algebraic: coeff, factors = dup_ext_factor(f, K0) else: if not K0.is_Exact: K0_inexact, K0 = K0, K0.get_exact() f = dup_convert(f, K0_inexact, K0) else: K0_inexact = None if K0.is_Field: K = K0.get_ring() denom, f = dup_clear_denoms(f, K0, K) f = dup_convert(f, K0, K) else: K = K0 if K.is_ZZ: coeff, factors = dup_zz_factor(f, K) elif K.is_Poly: f, u = dmp_inject(f, 0, K) coeff, factors = dmp_factor_list(f, u, K.dom) for i, (f, k) in enumerate(factors): factors[i] = (dmp_eject(f, u, K), k) coeff = K.convert(coeff, K.dom) else: # pragma: no cover raise DomainError('factorization not supported over %s' % K0) if K0.is_Field: for i, (f, k) in enumerate(factors): factors[i] = (dup_convert(f, K, K0), k) coeff = K0.convert(coeff, K) coeff = K0.quo(coeff, denom) if K0_inexact: for i, (f, k) in enumerate(factors): max_norm = dup_max_norm(f, K0) f = dup_quo_ground(f, max_norm, K0) f = dup_convert(f, K0, K0_inexact) factors[i] = (f, k) coeff = K0.mul(coeff, K0.pow(max_norm, k)) coeff = K0_inexact.convert(coeff, K0) K0 = K0_inexact if j: factors.insert(0, ([K0.one, K0.zero], j)) return coeff*cont, _sort_factors(factors) def dup_factor_list_include(f, K): """Factor polynomials into irreducibles in `K[x]`. """ coeff, factors = dup_factor_list(f, K) if not factors: return [(dup_strip([coeff]), 1)] else: g = dup_mul_ground(factors[0][0], coeff, K) return [(g, factors[0][1])] + factors[1:] def dmp_factor_list(f, u, K0): """Factor polynomials into irreducibles in `K[X]`. """ if not u: return dup_factor_list(f, K0) J, f = dmp_terms_gcd(f, u, K0) cont, f = dmp_ground_primitive(f, u, K0) if K0.is_FiniteField: # pragma: no cover coeff, factors = dmp_gf_factor(f, u, K0) elif K0.is_Algebraic: coeff, factors = dmp_ext_factor(f, u, K0) else: if not K0.is_Exact: K0_inexact, K0 = K0, K0.get_exact() f = dmp_convert(f, u, K0_inexact, K0) else: K0_inexact = None if K0.is_Field: K = K0.get_ring() denom, f = dmp_clear_denoms(f, u, K0, K) f = dmp_convert(f, u, K0, K) else: K = K0 if K.is_ZZ: levels, f, v = dmp_exclude(f, u, K) coeff, factors = dmp_zz_factor(f, v, K) for i, (f, k) in enumerate(factors): factors[i] = (dmp_include(f, levels, v, K), k) elif K.is_Poly: f, v = dmp_inject(f, u, K) coeff, factors = dmp_factor_list(f, v, K.dom) for i, (f, k) in enumerate(factors): factors[i] = (dmp_eject(f, v, K), k) coeff = K.convert(coeff, K.dom) else: # pragma: no cover raise DomainError('factorization not supported over %s' % K0) if K0.is_Field: for i, (f, k) in enumerate(factors): factors[i] = (dmp_convert(f, u, K, K0), k) coeff = K0.convert(coeff, K) coeff = K0.quo(coeff, denom) if K0_inexact: for i, (f, k) in enumerate(factors): max_norm = dmp_max_norm(f, u, K0) f = dmp_quo_ground(f, max_norm, u, K0) f = dmp_convert(f, u, K0, K0_inexact) factors[i] = (f, k) coeff = K0.mul(coeff, K0.pow(max_norm, k)) coeff = K0_inexact.convert(coeff, K0) K0 = K0_inexact for i, j in enumerate(reversed(J)): if not j: continue term = {(0,)*(u - i) + (1,) + (0,)*i: K0.one} factors.insert(0, (dmp_from_dict(term, u, K0), j)) return coeff*cont, _sort_factors(factors) def dmp_factor_list_include(f, u, K): """Factor polynomials into irreducibles in `K[X]`. """ if not u: return dup_factor_list_include(f, K) coeff, factors = dmp_factor_list(f, u, K) if not factors: return [(dmp_ground(coeff, u), 1)] else: g = dmp_mul_ground(factors[0][0], coeff, u, K) return [(g, factors[0][1])] + factors[1:] def dup_irreducible_p(f, K): """Returns ``True`` if ``f`` has no factors over its domain. """ return dmp_irreducible_p(f, 0, K) def dmp_irreducible_p(f, u, K): """Returns ``True`` if ``f`` has no factors over its domain. """ _, factors = dmp_factor_list(f, u, K) if not factors: return True elif len(factors) > 1: return False else: _, k = factors[0] return k == 1

07b9c5abd589ce4c417f557a7308bf2c0bdbd7dda692f609fac5743f3aca3be7

r""" Sparse distributed elements of free modules over multivariate (generalized) polynomial rings. This code and its data structures are very much like the distributed polynomials, except that the first "exponent" of the monomial is a module generator index. That is, the multi-exponent ``(i, e_1, ..., e_n)`` represents the "monomial" `x_1^{e_1} \cdots x_n^{e_n} f_i` of the free module `F` generated by `f_1, \ldots, f_r` over (a localization of) the ring `K[x_1, \ldots, x_n]`. A module element is simply stored as a list of terms ordered by the monomial order. Here a term is a pair of a multi-exponent and a coefficient. In general, this coefficient should never be zero (since it can then be omitted). The zero module element is stored as an empty list. The main routines are ``sdm_nf_mora`` and ``sdm_groebner`` which can be used to compute, respectively, weak normal forms and standard bases. They work with arbitrary (not necessarily global) monomial orders. In general, product orders have to be used to construct valid monomial orders for modules. However, ``lex`` can be used as-is. Note that the "level" (number of variables, i.e. parameter u+1 in distributedpolys.py) is never needed in this code. The main reference for this file is [SCA], "A Singular Introduction to Commutative Algebra". """ from __future__ import print_function, division from itertools import permutations from sympy.polys.monomials import ( monomial_mul, monomial_lcm, monomial_div, monomial_deg ) from sympy.polys.polytools import Poly from sympy.polys.polyutils import parallel_dict_from_expr from sympy import S, sympify from sympy.core.compatibility import range # Additional monomial tools. def sdm_monomial_mul(M, X): """ Multiply tuple ``X`` representing a monomial of `K[X]` into the tuple ``M`` representing a monomial of `F`. Examples ======== Multiplying `xy^3` into `x f_1` yields `x^2 y^3 f_1`: >>> from sympy.polys.distributedmodules import sdm_monomial_mul >>> sdm_monomial_mul((1, 1, 0), (1, 3)) (1, 2, 3) """ return (M[0],) + monomial_mul(X, M[1:]) def sdm_monomial_deg(M): """ Return the total degree of ``M``. Examples ======== For example, the total degree of `x^2 y f_5` is 3: >>> from sympy.polys.distributedmodules import sdm_monomial_deg >>> sdm_monomial_deg((5, 2, 1)) 3 """ return monomial_deg(M[1:]) def sdm_monomial_lcm(A, B): r""" Return the "least common multiple" of ``A`` and ``B``. IF `A = M e_j` and `B = N e_j`, where `M` and `N` are polynomial monomials, this returns `\lcm(M, N) e_j`. Note that ``A`` and ``B`` involve distinct monomials. Otherwise the result is undefined. Examples ======== >>> from sympy.polys.distributedmodules import sdm_monomial_lcm >>> sdm_monomial_lcm((1, 2, 3), (1, 0, 5)) (1, 2, 5) """ return (A[0],) + monomial_lcm(A[1:], B[1:]) def sdm_monomial_divides(A, B): """ Does there exist a (polynomial) monomial X such that XA = B? Examples ======== Positive examples: In the following examples, the monomial is given in terms of x, y and the generator(s), f_1, f_2 etc. The tuple form of that monomial is used in the call to sdm_monomial_divides. Note: the generator appears last in the expression but first in the tuple and other factors appear in the same order that they appear in the monomial expression. `A = f_1` divides `B = f_1` >>> from sympy.polys.distributedmodules import sdm_monomial_divides >>> sdm_monomial_divides((1, 0, 0), (1, 0, 0)) True `A = f_1` divides `B = x^2 y f_1` >>> sdm_monomial_divides((1, 0, 0), (1, 2, 1)) True `A = xy f_5` divides `B = x^2 y f_5` >>> sdm_monomial_divides((5, 1, 1), (5, 2, 1)) True Negative examples: `A = f_1` does not divide `B = f_2` >>> sdm_monomial_divides((1, 0, 0), (2, 0, 0)) False `A = x f_1` does not divide `B = f_1` >>> sdm_monomial_divides((1, 1, 0), (1, 0, 0)) False `A = xy^2 f_5` does not divide `B = y f_5` >>> sdm_monomial_divides((5, 1, 2), (5, 0, 1)) False """ return A[0] == B[0] and all(a <= b for a, b in zip(A[1:], B[1:])) # The actual distributed modules code. def sdm_LC(f, K): """Returns the leading coeffcient of ``f``. """ if not f: return K.zero else: return f[0][1] def sdm_to_dict(f): """Make a dictionary from a distributed polynomial. """ return dict(f) def sdm_from_dict(d, O): """ Create an sdm from a dictionary. Here ``O`` is the monomial order to use. Examples ======== >>> from sympy.polys.distributedmodules import sdm_from_dict >>> from sympy.polys import QQ, lex >>> dic = {(1, 1, 0): QQ(1), (1, 0, 0): QQ(2), (0, 1, 0): QQ(0)} >>> sdm_from_dict(dic, lex) [((1, 1, 0), 1), ((1, 0, 0), 2)] """ return sdm_strip(sdm_sort(list(d.items()), O)) def sdm_sort(f, O): """Sort terms in ``f`` using the given monomial order ``O``. """ return sorted(f, key=lambda term: O(term[0]), reverse=True) def sdm_strip(f): """Remove terms with zero coefficients from ``f`` in ``K[X]``. """ return [ (monom, coeff) for monom, coeff in f if coeff ] def sdm_add(f, g, O, K): """ Add two module elements ``f``, ``g``. Addition is done over the ground field ``K``, monomials are ordered according to ``O``. Examples ======== All examples use lexicographic order. `(xy f_1) + (f_2) = f_2 + xy f_1` >>> from sympy.polys.distributedmodules import sdm_add >>> from sympy.polys import lex, QQ >>> sdm_add([((1, 1, 1), QQ(1))], [((2, 0, 0), QQ(1))], lex, QQ) [((2, 0, 0), 1), ((1, 1, 1), 1)] `(xy f_1) + (-xy f_1)` = 0` >>> sdm_add([((1, 1, 1), QQ(1))], [((1, 1, 1), QQ(-1))], lex, QQ) [] `(f_1) + (2f_1) = 3f_1` >>> sdm_add([((1, 0, 0), QQ(1))], [((1, 0, 0), QQ(2))], lex, QQ) [((1, 0, 0), 3)] `(yf_1) + (xf_1) = xf_1 + yf_1` >>> sdm_add([((1, 0, 1), QQ(1))], [((1, 1, 0), QQ(1))], lex, QQ) [((1, 1, 0), 1), ((1, 0, 1), 1)] """ h = dict(f) for monom, c in g: if monom in h: coeff = h[monom] + c if not coeff: del h[monom] else: h[monom] = coeff else: h[monom] = c return sdm_from_dict(h, O) def sdm_LM(f): r""" Returns the leading monomial of ``f``. Only valid if `f \ne 0`. Examples ======== >>> from sympy.polys.distributedmodules import sdm_LM, sdm_from_dict >>> from sympy.polys import QQ, lex >>> dic = {(1, 2, 3): QQ(1), (4, 0, 0): QQ(1), (4, 0, 1): QQ(1)} >>> sdm_LM(sdm_from_dict(dic, lex)) (4, 0, 1) """ return f[0][0] def sdm_LT(f): r""" Returns the leading term of ``f``. Only valid if `f \ne 0`. Examples ======== >>> from sympy.polys.distributedmodules import sdm_LT, sdm_from_dict >>> from sympy.polys import QQ, lex >>> dic = {(1, 2, 3): QQ(1), (4, 0, 0): QQ(2), (4, 0, 1): QQ(3)} >>> sdm_LT(sdm_from_dict(dic, lex)) ((4, 0, 1), 3) """ return f[0] def sdm_mul_term(f, term, O, K): """ Multiply a distributed module element ``f`` by a (polynomial) term ``term``. Multiplication of coefficients is done over the ground field ``K``, and monomials are ordered according to ``O``. Examples ======== `0 f_1 = 0` >>> from sympy.polys.distributedmodules import sdm_mul_term >>> from sympy.polys import lex, QQ >>> sdm_mul_term([((1, 0, 0), QQ(1))], ((0, 0), QQ(0)), lex, QQ) [] `x 0 = 0` >>> sdm_mul_term([], ((1, 0), QQ(1)), lex, QQ) [] `(x) (f_1) = xf_1` >>> sdm_mul_term([((1, 0, 0), QQ(1))], ((1, 0), QQ(1)), lex, QQ) [((1, 1, 0), 1)] `(2xy) (3x f_1 + 4y f_2) = 8xy^2 f_2 + 6x^2y f_1` >>> f = [((2, 0, 1), QQ(4)), ((1, 1, 0), QQ(3))] >>> sdm_mul_term(f, ((1, 1), QQ(2)), lex, QQ) [((2, 1, 2), 8), ((1, 2, 1), 6)] """ X, c = term if not f or not c: return [] else: if K.is_one(c): return [ (sdm_monomial_mul(f_M, X), f_c) for f_M, f_c in f ] else: return [ (sdm_monomial_mul(f_M, X), f_c * c) for f_M, f_c in f ] def sdm_zero(): """Return the zero module element.""" return [] def sdm_deg(f): """ Degree of ``f``. This is the maximum of the degrees of all its monomials. Invalid if ``f`` is zero. Examples ======== >>> from sympy.polys.distributedmodules import sdm_deg >>> sdm_deg([((1, 2, 3), 1), ((10, 0, 1), 1), ((2, 3, 4), 4)]) 7 """ return max(sdm_monomial_deg(M[0]) for M in f) # Conversion def sdm_from_vector(vec, O, K, **opts): """ Create an sdm from an iterable of expressions. Coefficients are created in the ground field ``K``, and terms are ordered according to monomial order ``O``. Named arguments are passed on to the polys conversion code and can be used to specify for example generators. Examples ======== >>> from sympy.polys.distributedmodules import sdm_from_vector >>> from sympy.abc import x, y, z >>> from sympy.polys import QQ, lex >>> sdm_from_vector([x**2+y**2, 2*z], lex, QQ) [((1, 0, 0, 1), 2), ((0, 2, 0, 0), 1), ((0, 0, 2, 0), 1)] """ dics, gens = parallel_dict_from_expr(sympify(vec), **opts) dic = {} for i, d in enumerate(dics): for k, v in d.items(): dic[(i,) + k] = K.convert(v) return sdm_from_dict(dic, O) def sdm_to_vector(f, gens, K, n=None): """ Convert sdm ``f`` into a list of polynomial expressions. The generators for the polynomial ring are specified via ``gens``. The rank of the module is guessed, or passed via ``n``. The ground field is assumed to be ``K``. Examples ======== >>> from sympy.polys.distributedmodules import sdm_to_vector >>> from sympy.abc import x, y, z >>> from sympy.polys import QQ, lex >>> f = [((1, 0, 0, 1), QQ(2)), ((0, 2, 0, 0), QQ(1)), ((0, 0, 2, 0), QQ(1))] >>> sdm_to_vector(f, [x, y, z], QQ) [x**2 + y**2, 2*z] """ dic = sdm_to_dict(f) dics = {} for k, v in dic.items(): dics.setdefault(k[0], []).append((k[1:], v)) n = n or len(dics) res = [] for k in range(n): if k in dics: res.append(Poly(dict(dics[k]), gens=gens, domain=K).as_expr()) else: res.append(S.Zero) return res # Algorithms. def sdm_spoly(f, g, O, K, phantom=None): """ Compute the generalized s-polynomial of ``f`` and ``g``. The ground field is assumed to be ``K``, and monomials ordered according to ``O``. This is invalid if either of ``f`` or ``g`` is zero. If the leading terms of `f` and `g` involve different basis elements of `F`, their s-poly is defined to be zero. Otherwise it is a certain linear combination of `f` and `g` in which the leading terms cancel. See [SCA, defn 2.3.6] for details. If ``phantom`` is not ``None``, it should be a pair of module elements on which to perform the same operation(s) as on ``f`` and ``g``. The in this case both results are returned. Examples ======== >>> from sympy.polys.distributedmodules import sdm_spoly >>> from sympy.polys import QQ, lex >>> f = [((2, 1, 1), QQ(1)), ((1, 0, 1), QQ(1))] >>> g = [((2, 3, 0), QQ(1))] >>> h = [((1, 2, 3), QQ(1))] >>> sdm_spoly(f, h, lex, QQ) [] >>> sdm_spoly(f, g, lex, QQ) [((1, 2, 1), 1)] """ if not f or not g: return sdm_zero() LM1 = sdm_LM(f) LM2 = sdm_LM(g) if LM1[0] != LM2[0]: return sdm_zero() LM1 = LM1[1:] LM2 = LM2[1:] lcm = monomial_lcm(LM1, LM2) m1 = monomial_div(lcm, LM1) m2 = monomial_div(lcm, LM2) c = K.quo(-sdm_LC(f, K), sdm_LC(g, K)) r1 = sdm_add(sdm_mul_term(f, (m1, K.one), O, K), sdm_mul_term(g, (m2, c), O, K), O, K) if phantom is None: return r1 r2 = sdm_add(sdm_mul_term(phantom[0], (m1, K.one), O, K), sdm_mul_term(phantom[1], (m2, c), O, K), O, K) return r1, r2 def sdm_ecart(f): """ Compute the ecart of ``f``. This is defined to be the difference of the total degree of `f` and the total degree of the leading monomial of `f` [SCA, defn 2.3.7]. Invalid if f is zero. Examples ======== >>> from sympy.polys.distributedmodules import sdm_ecart >>> sdm_ecart([((1, 2, 3), 1), ((1, 0, 1), 1)]) 0 >>> sdm_ecart([((2, 2, 1), 1), ((1, 5, 1), 1)]) 3 """ return sdm_deg(f) - sdm_monomial_deg(sdm_LM(f)) def sdm_nf_mora(f, G, O, K, phantom=None): r""" Compute a weak normal form of ``f`` with respect to ``G`` and order ``O``. The ground field is assumed to be ``K``, and monomials ordered according to ``O``. Weak normal forms are defined in [SCA, defn 2.3.3]. They are not unique. This function deterministically computes a weak normal form, depending on the order of `G`. The most important property of a weak normal form is the following: if `R` is the ring associated with the monomial ordering (if the ordering is global, we just have `R = K[x_1, \ldots, x_n]`, otherwise it is a certain localization thereof), `I` any ideal of `R` and `G` a standard basis for `I`, then for any `f \in R`, we have `f \in I` if and only if `NF(f | G) = 0`. This is the generalized Mora algorithm for computing weak normal forms with respect to arbitrary monomial orders [SCA, algorithm 2.3.9]. If ``phantom`` is not ``None``, it should be a pair of "phantom" arguments on which to perform the same computations as on ``f``, ``G``, both results are then returned. """ from itertools import repeat h = f T = list(G) if phantom is not None: # "phantom" variables with suffix p hp = phantom[0] Tp = list(phantom[1]) phantom = True else: Tp = repeat([]) phantom = False while h: # TODO better data structure!!! Th = [(g, sdm_ecart(g), gp) for g, gp in zip(T, Tp) if sdm_monomial_divides(sdm_LM(g), sdm_LM(h))] if not Th: break g, _, gp = min(Th, key=lambda x: x[1]) if sdm_ecart(g) > sdm_ecart(h): T.append(h) if phantom: Tp.append(hp) if phantom: h, hp = sdm_spoly(h, g, O, K, phantom=(hp, gp)) else: h = sdm_spoly(h, g, O, K) if phantom: return h, hp return h def sdm_nf_buchberger(f, G, O, K, phantom=None): r""" Compute a weak normal form of ``f`` with respect to ``G`` and order ``O``. The ground field is assumed to be ``K``, and monomials ordered according to ``O``. This is the standard Buchberger algorithm for computing weak normal forms with respect to *global* monomial orders [SCA, algorithm 1.6.10]. If ``phantom`` is not ``None``, it should be a pair of "phantom" arguments on which to perform the same computations as on ``f``, ``G``, both results are then returned. """ from itertools import repeat h = f T = list(G) if phantom is not None: # "phantom" variables with suffix p hp = phantom[0] Tp = list(phantom[1]) phantom = True else: Tp = repeat([]) phantom = False while h: try: g, gp = next((g, gp) for g, gp in zip(T, Tp) if sdm_monomial_divides(sdm_LM(g), sdm_LM(h))) except StopIteration: break if phantom: h, hp = sdm_spoly(h, g, O, K, phantom=(hp, gp)) else: h = sdm_spoly(h, g, O, K) if phantom: return h, hp return h def sdm_nf_buchberger_reduced(f, G, O, K): r""" Compute a reduced normal form of ``f`` with respect to ``G`` and order ``O``. The ground field is assumed to be ``K``, and monomials ordered according to ``O``. In contrast to weak normal forms, reduced normal forms *are* unique, but their computation is more expensive. This is the standard Buchberger algorithm for computing reduced normal forms with respect to *global* monomial orders [SCA, algorithm 1.6.11]. The ``pantom`` option is not supported, so this normal form cannot be used as a normal form for the "extended" groebner algorithm. """ h = sdm_zero() g = f while g: g = sdm_nf_buchberger(g, G, O, K) if g: h = sdm_add(h, [sdm_LT(g)], O, K) g = g[1:] return h def sdm_groebner(G, NF, O, K, extended=False): """ Compute a minimal standard basis of ``G`` with respect to order ``O``. The algorithm uses a normal form ``NF``, for example ``sdm_nf_mora``. The ground field is assumed to be ``K``, and monomials ordered according to ``O``. Let `N` denote the submodule generated by elements of `G`. A standard basis for `N` is a subset `S` of `N`, such that `in(S) = in(N)`, where for any subset `X` of `F`, `in(X)` denotes the submodule generated by the initial forms of elements of `X`. [SCA, defn 2.3.2] A standard basis is called minimal if no subset of it is a standard basis. One may show that standard bases are always generating sets. Minimal standard bases are not unique. This algorithm computes a deterministic result, depending on the particular order of `G`. If ``extended=True``, also compute the transition matrix from the initial generators to the groebner basis. That is, return a list of coefficient vectors, expressing the elements of the groebner basis in terms of the elements of ``G``. This functions implements the "sugar" strategy, see Giovini et al: "One sugar cube, please" OR Selection strategies in Buchberger algorithm. """ # The critical pair set. # A critical pair is stored as (i, j, s, t) where (i, j) defines the pair # (by indexing S), s is the sugar of the pair, and t is the lcm of their # leading monomials. P = [] # The eventual standard basis. S = [] Sugars = [] def Ssugar(i, j): """Compute the sugar of the S-poly corresponding to (i, j).""" LMi = sdm_LM(S[i]) LMj = sdm_LM(S[j]) return max(Sugars[i] - sdm_monomial_deg(LMi), Sugars[j] - sdm_monomial_deg(LMj)) \ + sdm_monomial_deg(sdm_monomial_lcm(LMi, LMj)) ourkey = lambda p: (p[2], O(p[3]), p[1]) def update(f, sugar, P): """Add f with sugar ``sugar`` to S, update P.""" if not f: return P k = len(S) S.append(f) Sugars.append(sugar) LMf = sdm_LM(f) def removethis(pair): i, j, s, t = pair if LMf[0] != t[0]: return False tik = sdm_monomial_lcm(LMf, sdm_LM(S[i])) tjk = sdm_monomial_lcm(LMf, sdm_LM(S[j])) return tik != t and tjk != t and sdm_monomial_divides(tik, t) and \ sdm_monomial_divides(tjk, t) # apply the chain criterion P = [p for p in P if not removethis(p)] # new-pair set N = [(i, k, Ssugar(i, k), sdm_monomial_lcm(LMf, sdm_LM(S[i]))) for i in range(k) if LMf[0] == sdm_LM(S[i])[0]] # TODO apply the product criterion? N.sort(key=ourkey) remove = set() for i, p in enumerate(N): for j in range(i + 1, len(N)): if sdm_monomial_divides(p[3], N[j][3]): remove.add(j) # TODO mergesort? P.extend(reversed([p for i, p in enumerate(N) if not i in remove])) P.sort(key=ourkey, reverse=True) # NOTE reverse-sort, because we want to pop from the end return P # Figure out the number of generators in the ground ring. try: # NOTE: we look for the first non-zero vector, take its first monomial # the number of generators in the ring is one less than the length # (since the zeroth entry is for the module generators) numgens = len(next(x[0] for x in G if x)[0]) - 1 except StopIteration: # No non-zero elements in G ... if extended: return [], [] return [] # This list will store expressions of the elements of S in terms of the # initial generators coefficients = [] # First add all the elements of G to S for i, f in enumerate(G): P = update(f, sdm_deg(f), P) if extended and f: coefficients.append(sdm_from_dict({(i,) + (0,)*numgens: K(1)}, O)) # Now carry out the buchberger algorithm. while P: i, j, s, t = P.pop() f, g = S[i], S[j] if extended: sp, coeff = sdm_spoly(f, g, O, K, phantom=(coefficients[i], coefficients[j])) h, hcoeff = NF(sp, S, O, K, phantom=(coeff, coefficients)) if h: coefficients.append(hcoeff) else: h = NF(sdm_spoly(f, g, O, K), S, O, K) P = update(h, Ssugar(i, j), P) # Finally interreduce the standard basis. # (TODO again, better data structures) S = set((tuple(f), i) for i, f in enumerate(S)) for (a, ai), (b, bi) in permutations(S, 2): A = sdm_LM(a) B = sdm_LM(b) if sdm_monomial_divides(A, B) and (b, bi) in S and (a, ai) in S: S.remove((b, bi)) L = sorted(((list(f), i) for f, i in S), key=lambda p: O(sdm_LM(p[0])), reverse=True) res = [x[0] for x in L] if extended: return res, [coefficients[i] for _, i in L] return res

35054c0c09a2c51bcdd2b876f3ced05687ffeee97ec92c063482ce9e391b74f1

""" Generic Unification algorithm for expression trees with lists of children This implementation is a direct translation of Artificial Intelligence: A Modern Approach by Stuart Russel and Peter Norvig Second edition, section 9.2, page 276 It is modified in the following ways: 1. We allow associative and commutative Compound expressions. This results in combinatorial blowup. 2. We explore the tree lazily. 3. We provide generic interfaces to symbolic algebra libraries in Python. A more traditional version can be found here http://aima.cs.berkeley.edu/python/logic.html """ from __future__ import print_function, division from sympy.core.compatibility import range from sympy.utilities.iterables import kbins class Compound(object): """ A little class to represent an interior node in the tree This is analogous to SymPy.Basic for non-Atoms """ def __init__(self, op, args): self.op = op self.args = args def __eq__(self, other): return (type(self) == type(other) and self.op == other.op and self.args == other.args) def __hash__(self): return hash((type(self), self.op, self.args)) def __str__(self): return "%s[%s]" % (str(self.op), ', '.join(map(str, self.args))) class Variable(object): """ A Wild token """ def __init__(self, arg): self.arg = arg def __eq__(self, other): return type(self) == type(other) and self.arg == other.arg def __hash__(self): return hash((type(self), self.arg)) def __str__(self): return "Variable(%s)" % str(self.arg) class CondVariable(object): """ A wild token that matches conditionally arg - a wild token valid - an additional constraining function on a match """ def __init__(self, arg, valid): self.arg = arg self.valid = valid def __eq__(self, other): return (type(self) == type(other) and self.arg == other.arg and self.valid == other.valid) def __hash__(self): return hash((type(self), self.arg, self.valid)) def __str__(self): return "CondVariable(%s)" % str(self.arg) def unify(x, y, s=None, **fns): """ Unify two expressions Parameters ========== x, y - expression trees containing leaves, Compounds and Variables s - a mapping of variables to subtrees Returns ======= lazy sequence of mappings {Variable: subtree} Examples ======== >>> from sympy.unify.core import unify, Compound, Variable >>> expr = Compound("Add", ("x", "y")) >>> pattern = Compound("Add", ("x", Variable("a"))) >>> next(unify(expr, pattern, {})) {Variable(a): 'y'} """ s = s or {} if x == y: yield s elif isinstance(x, (Variable, CondVariable)): for match in unify_var(x, y, s, **fns): yield match elif isinstance(y, (Variable, CondVariable)): for match in unify_var(y, x, s, **fns): yield match elif isinstance(x, Compound) and isinstance(y, Compound): is_commutative = fns.get('is_commutative', lambda x: False) is_associative = fns.get('is_associative', lambda x: False) for sop in unify(x.op, y.op, s, **fns): if is_associative(x) and is_associative(y): a, b = (x, y) if len(x.args) < len(y.args) else (y, x) if is_commutative(x) and is_commutative(y): combs = allcombinations(a.args, b.args, 'commutative') else: combs = allcombinations(a.args, b.args, 'associative') for aaargs, bbargs in combs: aa = [unpack(Compound(a.op, arg)) for arg in aaargs] bb = [unpack(Compound(b.op, arg)) for arg in bbargs] for match in unify(aa, bb, sop, **fns): yield match elif len(x.args) == len(y.args): for match in unify(x.args, y.args, sop, **fns): yield match elif is_args(x) and is_args(y) and len(x) == len(y): if len(x) == 0: yield s else: for shead in unify(x[0], y[0], s, **fns): for match in unify(x[1:], y[1:], shead, **fns): yield match def unify_var(var, x, s, **fns): if var in s: for match in unify(s[var], x, s, **fns): yield match elif occur_check(var, x): pass elif isinstance(var, CondVariable) and var.valid(x): yield assoc(s, var, x) elif isinstance(var, Variable): yield assoc(s, var, x) def occur_check(var, x): """ var occurs in subtree owned by x? """ if var == x: return True elif isinstance(x, Compound): return occur_check(var, x.args) elif is_args(x): if any(occur_check(var, xi) for xi in x): return True return False def assoc(d, key, val): """ Return copy of d with key associated to val """ d = d.copy() d[key] = val return d def is_args(x): """ Is x a traditional iterable? """ return type(x) in (tuple, list, set) def unpack(x): if isinstance(x, Compound) and len(x.args) == 1: return x.args[0] else: return x def allcombinations(A, B, ordered): """ Restructure A and B to have the same number of elements ordered must be either 'commutative' or 'associative' A and B can be rearranged so that the larger of the two lists is reorganized into smaller sublists. Examples ======== >>> from sympy.unify.core import allcombinations >>> for x in allcombinations((1, 2, 3), (5, 6), 'associative'): print(x) (((1,), (2, 3)), ((5,), (6,))) (((1, 2), (3,)), ((5,), (6,))) >>> for x in allcombinations((1, 2, 3), (5, 6), 'commutative'): print(x) (((1,), (2, 3)), ((5,), (6,))) (((1, 2), (3,)), ((5,), (6,))) (((1,), (3, 2)), ((5,), (6,))) (((1, 3), (2,)), ((5,), (6,))) (((2,), (1, 3)), ((5,), (6,))) (((2, 1), (3,)), ((5,), (6,))) (((2,), (3, 1)), ((5,), (6,))) (((2, 3), (1,)), ((5,), (6,))) (((3,), (1, 2)), ((5,), (6,))) (((3, 1), (2,)), ((5,), (6,))) (((3,), (2, 1)), ((5,), (6,))) (((3, 2), (1,)), ((5,), (6,))) """ if ordered == "commutative": ordered = 11 if ordered == "associative": ordered = None sm, bg = (A, B) if len(A) < len(B) else (B, A) for part in kbins(list(range(len(bg))), len(sm), ordered=ordered): if bg == B: yield tuple((a,) for a in A), partition(B, part) else: yield partition(A, part), tuple((b,) for b in B) def partition(it, part): """ Partition a tuple/list into pieces defined by indices Examples ======== >>> from sympy.unify.core import partition >>> partition((10, 20, 30, 40), [[0, 1, 2], [3]]) ((10, 20, 30), (40,)) """ return type(it)([index(it, ind) for ind in part]) def index(it, ind): """ Fancy indexing into an indexable iterable (tuple, list) Examples ======== >>> from sympy.unify.core import index >>> index([10, 20, 30], (1, 2, 0)) [20, 30, 10] """ return type(it)([it[i] for i in ind])

7630370764b0a391a02f5671f13c00f053246117dcddc0402df3c8c420adf511

""" SymPy interface to Unification engine See sympy.unify for module level docstring See sympy.unify.core for algorithmic docstring """ from __future__ import print_function, division from sympy.core import Basic, Add, Mul, Pow from sympy.core.operations import AssocOp, LatticeOp from sympy.matrices import MatAdd, MatMul, MatrixExpr from sympy.sets.sets import Union, Intersection, FiniteSet from sympy.unify.core import Compound, Variable, CondVariable from sympy.unify import core basic_new_legal = [MatrixExpr] eval_false_legal = [AssocOp, Pow, FiniteSet] illegal = [LatticeOp] def sympy_associative(op): assoc_ops = (AssocOp, MatAdd, MatMul, Union, Intersection, FiniteSet) return any(issubclass(op, aop) for aop in assoc_ops) def sympy_commutative(op): comm_ops = (Add, MatAdd, Union, Intersection, FiniteSet) return any(issubclass(op, cop) for cop in comm_ops) def is_associative(x): return isinstance(x, Compound) and sympy_associative(x.op) def is_commutative(x): if not isinstance(x, Compound): return False if sympy_commutative(x.op): return True if issubclass(x.op, Mul): return all(construct(arg).is_commutative for arg in x.args) def mk_matchtype(typ): def matchtype(x): return (isinstance(x, typ) or isinstance(x, Compound) and issubclass(x.op, typ)) return matchtype def deconstruct(s, variables=()): """ Turn a SymPy object into a Compound """ if s in variables: return Variable(s) if isinstance(s, (Variable, CondVariable)): return s if not isinstance(s, Basic) or s.is_Atom: return s return Compound(s.__class__, tuple(deconstruct(arg, variables) for arg in s.args)) def construct(t): """ Turn a Compound into a SymPy object """ if isinstance(t, (Variable, CondVariable)): return t.arg if not isinstance(t, Compound): return t if any(issubclass(t.op, cls) for cls in eval_false_legal): return t.op(*map(construct, t.args), evaluate=False) elif any(issubclass(t.op, cls) for cls in basic_new_legal): return Basic.__new__(t.op, *map(construct, t.args)) else: return t.op(*map(construct, t.args)) def rebuild(s): """ Rebuild a SymPy expression This removes harm caused by Expr-Rules interactions """ return construct(deconstruct(s)) def unify(x, y, s=None, variables=(), **kwargs): """ Structural unification of two expressions/patterns Examples ======== >>> from sympy.unify.usympy import unify >>> from sympy import Basic, cos >>> from sympy.abc import x, y, z, p, q >>> next(unify(Basic(1, 2), Basic(1, x), variables=[x])) {x: 2} >>> expr = 2*x + y + z >>> pattern = 2*p + q >>> next(unify(expr, pattern, {}, variables=(p, q))) {p: x, q: y + z} Unification supports commutative and associative matching >>> expr = x + y + z >>> pattern = p + q >>> len(list(unify(expr, pattern, {}, variables=(p, q)))) 12 Symbols not indicated to be variables are treated as literal, else they are wild-like and match anything in a sub-expression. >>> expr = x*y*z + 3 >>> pattern = x*y + 3 >>> next(unify(expr, pattern, {}, variables=[x, y])) {x: y, y: x*z} The x and y of the pattern above were in a Mul and matched factors in the Mul of expr. Here, a single symbol matches an entire term: >>> expr = x*y + 3 >>> pattern = p + 3 >>> next(unify(expr, pattern, {}, variables=[p])) {p: x*y} """ decons = lambda x: deconstruct(x, variables) s = s or {} s = dict((decons(k), decons(v)) for k, v in s.items()) ds = core.unify(decons(x), decons(y), s, is_associative=is_associative, is_commutative=is_commutative, **kwargs) for d in ds: yield dict((construct(k), construct(v)) for k, v in d.items())